| File: | lib/Analysis/ScalarEvolution.cpp |
| Location: | line 7062, column 15 |
| Description: | Value stored to 'MaxBECount' during its initialization is never read |
| 1 | //===- ScalarEvolution.cpp - Scalar Evolution Analysis --------------------===// |
| 2 | // |
| 3 | // The LLVM Compiler Infrastructure |
| 4 | // |
| 5 | // This file is distributed under the University of Illinois Open Source |
| 6 | // License. See LICENSE.TXT for details. |
| 7 | // |
| 8 | //===----------------------------------------------------------------------===// |
| 9 | // |
| 10 | // This file contains the implementation of the scalar evolution analysis |
| 11 | // engine, which is used primarily to analyze expressions involving induction |
| 12 | // variables in loops. |
| 13 | // |
| 14 | // There are several aspects to this library. First is the representation of |
| 15 | // scalar expressions, which are represented as subclasses of the SCEV class. |
| 16 | // These classes are used to represent certain types of subexpressions that we |
| 17 | // can handle. We only create one SCEV of a particular shape, so |
| 18 | // pointer-comparisons for equality are legal. |
| 19 | // |
| 20 | // One important aspect of the SCEV objects is that they are never cyclic, even |
| 21 | // if there is a cycle in the dataflow for an expression (ie, a PHI node). If |
| 22 | // the PHI node is one of the idioms that we can represent (e.g., a polynomial |
| 23 | // recurrence) then we represent it directly as a recurrence node, otherwise we |
| 24 | // represent it as a SCEVUnknown node. |
| 25 | // |
| 26 | // In addition to being able to represent expressions of various types, we also |
| 27 | // have folders that are used to build the *canonical* representation for a |
| 28 | // particular expression. These folders are capable of using a variety of |
| 29 | // rewrite rules to simplify the expressions. |
| 30 | // |
| 31 | // Once the folders are defined, we can implement the more interesting |
| 32 | // higher-level code, such as the code that recognizes PHI nodes of various |
| 33 | // types, computes the execution count of a loop, etc. |
| 34 | // |
| 35 | // TODO: We should use these routines and value representations to implement |
| 36 | // dependence analysis! |
| 37 | // |
| 38 | //===----------------------------------------------------------------------===// |
| 39 | // |
| 40 | // There are several good references for the techniques used in this analysis. |
| 41 | // |
| 42 | // Chains of recurrences -- a method to expedite the evaluation |
| 43 | // of closed-form functions |
| 44 | // Olaf Bachmann, Paul S. Wang, Eugene V. Zima |
| 45 | // |
| 46 | // On computational properties of chains of recurrences |
| 47 | // Eugene V. Zima |
| 48 | // |
| 49 | // Symbolic Evaluation of Chains of Recurrences for Loop Optimization |
| 50 | // Robert A. van Engelen |
| 51 | // |
| 52 | // Efficient Symbolic Analysis for Optimizing Compilers |
| 53 | // Robert A. van Engelen |
| 54 | // |
| 55 | // Using the chains of recurrences algebra for data dependence testing and |
| 56 | // induction variable substitution |
| 57 | // MS Thesis, Johnie Birch |
| 58 | // |
| 59 | //===----------------------------------------------------------------------===// |
| 60 | |
| 61 | #include "llvm/Analysis/ScalarEvolution.h" |
| 62 | #include "llvm/ADT/Optional.h" |
| 63 | #include "llvm/ADT/STLExtras.h" |
| 64 | #include "llvm/ADT/SmallPtrSet.h" |
| 65 | #include "llvm/ADT/Statistic.h" |
| 66 | #include "llvm/Analysis/AssumptionTracker.h" |
| 67 | #include "llvm/Analysis/ConstantFolding.h" |
| 68 | #include "llvm/Analysis/InstructionSimplify.h" |
| 69 | #include "llvm/Analysis/LoopInfo.h" |
| 70 | #include "llvm/Analysis/ScalarEvolutionExpressions.h" |
| 71 | #include "llvm/Analysis/ValueTracking.h" |
| 72 | #include "llvm/IR/ConstantRange.h" |
| 73 | #include "llvm/IR/Constants.h" |
| 74 | #include "llvm/IR/DataLayout.h" |
| 75 | #include "llvm/IR/DerivedTypes.h" |
| 76 | #include "llvm/IR/Dominators.h" |
| 77 | #include "llvm/IR/GetElementPtrTypeIterator.h" |
| 78 | #include "llvm/IR/GlobalAlias.h" |
| 79 | #include "llvm/IR/GlobalVariable.h" |
| 80 | #include "llvm/IR/InstIterator.h" |
| 81 | #include "llvm/IR/Instructions.h" |
| 82 | #include "llvm/IR/LLVMContext.h" |
| 83 | #include "llvm/IR/Metadata.h" |
| 84 | #include "llvm/IR/Operator.h" |
| 85 | #include "llvm/Support/CommandLine.h" |
| 86 | #include "llvm/Support/Debug.h" |
| 87 | #include "llvm/Support/ErrorHandling.h" |
| 88 | #include "llvm/Support/MathExtras.h" |
| 89 | #include "llvm/Support/raw_ostream.h" |
| 90 | #include "llvm/Target/TargetLibraryInfo.h" |
| 91 | #include <algorithm> |
| 92 | using namespace llvm; |
| 93 | |
| 94 | #define DEBUG_TYPE"scalar-evolution" "scalar-evolution" |
| 95 | |
| 96 | STATISTIC(NumArrayLenItCounts,static llvm::Statistic NumArrayLenItCounts = { "scalar-evolution" , "Number of trip counts computed with array length", 0, 0 } |
| 97 | "Number of trip counts computed with array length")static llvm::Statistic NumArrayLenItCounts = { "scalar-evolution" , "Number of trip counts computed with array length", 0, 0 }; |
| 98 | STATISTIC(NumTripCountsComputed,static llvm::Statistic NumTripCountsComputed = { "scalar-evolution" , "Number of loops with predictable loop counts", 0, 0 } |
| 99 | "Number of loops with predictable loop counts")static llvm::Statistic NumTripCountsComputed = { "scalar-evolution" , "Number of loops with predictable loop counts", 0, 0 }; |
| 100 | STATISTIC(NumTripCountsNotComputed,static llvm::Statistic NumTripCountsNotComputed = { "scalar-evolution" , "Number of loops without predictable loop counts", 0, 0 } |
| 101 | "Number of loops without predictable loop counts")static llvm::Statistic NumTripCountsNotComputed = { "scalar-evolution" , "Number of loops without predictable loop counts", 0, 0 }; |
| 102 | STATISTIC(NumBruteForceTripCountsComputed,static llvm::Statistic NumBruteForceTripCountsComputed = { "scalar-evolution" , "Number of loops with trip counts computed by force", 0, 0 } |
| 103 | "Number of loops with trip counts computed by force")static llvm::Statistic NumBruteForceTripCountsComputed = { "scalar-evolution" , "Number of loops with trip counts computed by force", 0, 0 }; |
| 104 | |
| 105 | static cl::opt<unsigned> |
| 106 | MaxBruteForceIterations("scalar-evolution-max-iterations", cl::ReallyHidden, |
| 107 | cl::desc("Maximum number of iterations SCEV will " |
| 108 | "symbolically execute a constant " |
| 109 | "derived loop"), |
| 110 | cl::init(100)); |
| 111 | |
| 112 | // FIXME: Enable this with XDEBUG when the test suite is clean. |
| 113 | static cl::opt<bool> |
| 114 | VerifySCEV("verify-scev", |
| 115 | cl::desc("Verify ScalarEvolution's backedge taken counts (slow)")); |
| 116 | |
| 117 | INITIALIZE_PASS_BEGIN(ScalarEvolution, "scalar-evolution",static void* initializeScalarEvolutionPassOnce(PassRegistry & Registry) { |
| 118 | "Scalar Evolution Analysis", false, true)static void* initializeScalarEvolutionPassOnce(PassRegistry & Registry) { |
| 119 | INITIALIZE_PASS_DEPENDENCY(AssumptionTracker)initializeAssumptionTrackerPass(Registry); |
| 120 | INITIALIZE_PASS_DEPENDENCY(LoopInfo)initializeLoopInfoPass(Registry); |
| 121 | INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)initializeDominatorTreeWrapperPassPass(Registry); |
| 122 | INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfo)initializeTargetLibraryInfoPass(Registry); |
| 123 | INITIALIZE_PASS_END(ScalarEvolution, "scalar-evolution",PassInfo *PI = new PassInfo("Scalar Evolution Analysis", "scalar-evolution" , & ScalarEvolution ::ID, PassInfo::NormalCtor_t(callDefaultCtor < ScalarEvolution >), false, true); Registry.registerPass (*PI, true); return PI; } void llvm::initializeScalarEvolutionPass (PassRegistry &Registry) { static volatile sys::cas_flag initialized = 0; sys::cas_flag old_val = sys::CompareAndSwap(&initialized , 1, 0); if (old_val == 0) { initializeScalarEvolutionPassOnce (Registry); sys::MemoryFence(); AnnotateIgnoreWritesBegin("/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 124); AnnotateHappensBefore("/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 124, &initialized); initialized = 2; AnnotateIgnoreWritesEnd ("/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 124); } else { sys::cas_flag tmp = initialized; sys::MemoryFence (); while (tmp != 2) { tmp = initialized; sys::MemoryFence(); } } AnnotateHappensAfter("/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 124, &initialized); } |
| 124 | "Scalar Evolution Analysis", false, true)PassInfo *PI = new PassInfo("Scalar Evolution Analysis", "scalar-evolution" , & ScalarEvolution ::ID, PassInfo::NormalCtor_t(callDefaultCtor < ScalarEvolution >), false, true); Registry.registerPass (*PI, true); return PI; } void llvm::initializeScalarEvolutionPass (PassRegistry &Registry) { static volatile sys::cas_flag initialized = 0; sys::cas_flag old_val = sys::CompareAndSwap(&initialized , 1, 0); if (old_val == 0) { initializeScalarEvolutionPassOnce (Registry); sys::MemoryFence(); AnnotateIgnoreWritesBegin("/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 124); AnnotateHappensBefore("/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 124, &initialized); initialized = 2; AnnotateIgnoreWritesEnd ("/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 124); } else { sys::cas_flag tmp = initialized; sys::MemoryFence (); while (tmp != 2) { tmp = initialized; sys::MemoryFence(); } } AnnotateHappensAfter("/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 124, &initialized); } |
| 125 | char ScalarEvolution::ID = 0; |
| 126 | |
| 127 | //===----------------------------------------------------------------------===// |
| 128 | // SCEV class definitions |
| 129 | //===----------------------------------------------------------------------===// |
| 130 | |
| 131 | //===----------------------------------------------------------------------===// |
| 132 | // Implementation of the SCEV class. |
| 133 | // |
| 134 | |
| 135 | #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) |
| 136 | void SCEV::dump() const { |
| 137 | print(dbgs()); |
| 138 | dbgs() << '\n'; |
| 139 | } |
| 140 | #endif |
| 141 | |
| 142 | void SCEV::print(raw_ostream &OS) const { |
| 143 | switch (static_cast<SCEVTypes>(getSCEVType())) { |
| 144 | case scConstant: |
| 145 | cast<SCEVConstant>(this)->getValue()->printAsOperand(OS, false); |
| 146 | return; |
| 147 | case scTruncate: { |
| 148 | const SCEVTruncateExpr *Trunc = cast<SCEVTruncateExpr>(this); |
| 149 | const SCEV *Op = Trunc->getOperand(); |
| 150 | OS << "(trunc " << *Op->getType() << " " << *Op << " to " |
| 151 | << *Trunc->getType() << ")"; |
| 152 | return; |
| 153 | } |
| 154 | case scZeroExtend: { |
| 155 | const SCEVZeroExtendExpr *ZExt = cast<SCEVZeroExtendExpr>(this); |
| 156 | const SCEV *Op = ZExt->getOperand(); |
| 157 | OS << "(zext " << *Op->getType() << " " << *Op << " to " |
| 158 | << *ZExt->getType() << ")"; |
| 159 | return; |
| 160 | } |
| 161 | case scSignExtend: { |
| 162 | const SCEVSignExtendExpr *SExt = cast<SCEVSignExtendExpr>(this); |
| 163 | const SCEV *Op = SExt->getOperand(); |
| 164 | OS << "(sext " << *Op->getType() << " " << *Op << " to " |
| 165 | << *SExt->getType() << ")"; |
| 166 | return; |
| 167 | } |
| 168 | case scAddRecExpr: { |
| 169 | const SCEVAddRecExpr *AR = cast<SCEVAddRecExpr>(this); |
| 170 | OS << "{" << *AR->getOperand(0); |
| 171 | for (unsigned i = 1, e = AR->getNumOperands(); i != e; ++i) |
| 172 | OS << ",+," << *AR->getOperand(i); |
| 173 | OS << "}<"; |
| 174 | if (AR->getNoWrapFlags(FlagNUW)) |
| 175 | OS << "nuw><"; |
| 176 | if (AR->getNoWrapFlags(FlagNSW)) |
| 177 | OS << "nsw><"; |
| 178 | if (AR->getNoWrapFlags(FlagNW) && |
| 179 | !AR->getNoWrapFlags((NoWrapFlags)(FlagNUW | FlagNSW))) |
| 180 | OS << "nw><"; |
| 181 | AR->getLoop()->getHeader()->printAsOperand(OS, /*PrintType=*/false); |
| 182 | OS << ">"; |
| 183 | return; |
| 184 | } |
| 185 | case scAddExpr: |
| 186 | case scMulExpr: |
| 187 | case scUMaxExpr: |
| 188 | case scSMaxExpr: { |
| 189 | const SCEVNAryExpr *NAry = cast<SCEVNAryExpr>(this); |
| 190 | const char *OpStr = nullptr; |
| 191 | switch (NAry->getSCEVType()) { |
| 192 | case scAddExpr: OpStr = " + "; break; |
| 193 | case scMulExpr: OpStr = " * "; break; |
| 194 | case scUMaxExpr: OpStr = " umax "; break; |
| 195 | case scSMaxExpr: OpStr = " smax "; break; |
| 196 | } |
| 197 | OS << "("; |
| 198 | for (SCEVNAryExpr::op_iterator I = NAry->op_begin(), E = NAry->op_end(); |
| 199 | I != E; ++I) { |
| 200 | OS << **I; |
| 201 | if (std::next(I) != E) |
| 202 | OS << OpStr; |
| 203 | } |
| 204 | OS << ")"; |
| 205 | switch (NAry->getSCEVType()) { |
| 206 | case scAddExpr: |
| 207 | case scMulExpr: |
| 208 | if (NAry->getNoWrapFlags(FlagNUW)) |
| 209 | OS << "<nuw>"; |
| 210 | if (NAry->getNoWrapFlags(FlagNSW)) |
| 211 | OS << "<nsw>"; |
| 212 | } |
| 213 | return; |
| 214 | } |
| 215 | case scUDivExpr: { |
| 216 | const SCEVUDivExpr *UDiv = cast<SCEVUDivExpr>(this); |
| 217 | OS << "(" << *UDiv->getLHS() << " /u " << *UDiv->getRHS() << ")"; |
| 218 | return; |
| 219 | } |
| 220 | case scUnknown: { |
| 221 | const SCEVUnknown *U = cast<SCEVUnknown>(this); |
| 222 | Type *AllocTy; |
| 223 | if (U->isSizeOf(AllocTy)) { |
| 224 | OS << "sizeof(" << *AllocTy << ")"; |
| 225 | return; |
| 226 | } |
| 227 | if (U->isAlignOf(AllocTy)) { |
| 228 | OS << "alignof(" << *AllocTy << ")"; |
| 229 | return; |
| 230 | } |
| 231 | |
| 232 | Type *CTy; |
| 233 | Constant *FieldNo; |
| 234 | if (U->isOffsetOf(CTy, FieldNo)) { |
| 235 | OS << "offsetof(" << *CTy << ", "; |
| 236 | FieldNo->printAsOperand(OS, false); |
| 237 | OS << ")"; |
| 238 | return; |
| 239 | } |
| 240 | |
| 241 | // Otherwise just print it normally. |
| 242 | U->getValue()->printAsOperand(OS, false); |
| 243 | return; |
| 244 | } |
| 245 | case scCouldNotCompute: |
| 246 | OS << "***COULDNOTCOMPUTE***"; |
| 247 | return; |
| 248 | } |
| 249 | llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 249); |
| 250 | } |
| 251 | |
| 252 | Type *SCEV::getType() const { |
| 253 | switch (static_cast<SCEVTypes>(getSCEVType())) { |
| 254 | case scConstant: |
| 255 | return cast<SCEVConstant>(this)->getType(); |
| 256 | case scTruncate: |
| 257 | case scZeroExtend: |
| 258 | case scSignExtend: |
| 259 | return cast<SCEVCastExpr>(this)->getType(); |
| 260 | case scAddRecExpr: |
| 261 | case scMulExpr: |
| 262 | case scUMaxExpr: |
| 263 | case scSMaxExpr: |
| 264 | return cast<SCEVNAryExpr>(this)->getType(); |
| 265 | case scAddExpr: |
| 266 | return cast<SCEVAddExpr>(this)->getType(); |
| 267 | case scUDivExpr: |
| 268 | return cast<SCEVUDivExpr>(this)->getType(); |
| 269 | case scUnknown: |
| 270 | return cast<SCEVUnknown>(this)->getType(); |
| 271 | case scCouldNotCompute: |
| 272 | llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!")::llvm::llvm_unreachable_internal("Attempt to use a SCEVCouldNotCompute object!" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 272); |
| 273 | } |
| 274 | llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 274); |
| 275 | } |
| 276 | |
| 277 | bool SCEV::isZero() const { |
| 278 | if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this)) |
| 279 | return SC->getValue()->isZero(); |
| 280 | return false; |
| 281 | } |
| 282 | |
| 283 | bool SCEV::isOne() const { |
| 284 | if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this)) |
| 285 | return SC->getValue()->isOne(); |
| 286 | return false; |
| 287 | } |
| 288 | |
| 289 | bool SCEV::isAllOnesValue() const { |
| 290 | if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this)) |
| 291 | return SC->getValue()->isAllOnesValue(); |
| 292 | return false; |
| 293 | } |
| 294 | |
| 295 | /// isNonConstantNegative - Return true if the specified scev is negated, but |
| 296 | /// not a constant. |
| 297 | bool SCEV::isNonConstantNegative() const { |
| 298 | const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(this); |
| 299 | if (!Mul) return false; |
| 300 | |
| 301 | // If there is a constant factor, it will be first. |
| 302 | const SCEVConstant *SC = dyn_cast<SCEVConstant>(Mul->getOperand(0)); |
| 303 | if (!SC) return false; |
| 304 | |
| 305 | // Return true if the value is negative, this matches things like (-42 * V). |
| 306 | return SC->getValue()->getValue().isNegative(); |
| 307 | } |
| 308 | |
| 309 | SCEVCouldNotCompute::SCEVCouldNotCompute() : |
| 310 | SCEV(FoldingSetNodeIDRef(), scCouldNotCompute) {} |
| 311 | |
| 312 | bool SCEVCouldNotCompute::classof(const SCEV *S) { |
| 313 | return S->getSCEVType() == scCouldNotCompute; |
| 314 | } |
| 315 | |
| 316 | const SCEV *ScalarEvolution::getConstant(ConstantInt *V) { |
| 317 | FoldingSetNodeID ID; |
| 318 | ID.AddInteger(scConstant); |
| 319 | ID.AddPointer(V); |
| 320 | void *IP = nullptr; |
| 321 | if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S; |
| 322 | SCEV *S = new (SCEVAllocator) SCEVConstant(ID.Intern(SCEVAllocator), V); |
| 323 | UniqueSCEVs.InsertNode(S, IP); |
| 324 | return S; |
| 325 | } |
| 326 | |
| 327 | const SCEV *ScalarEvolution::getConstant(const APInt &Val) { |
| 328 | return getConstant(ConstantInt::get(getContext(), Val)); |
| 329 | } |
| 330 | |
| 331 | const SCEV * |
| 332 | ScalarEvolution::getConstant(Type *Ty, uint64_t V, bool isSigned) { |
| 333 | IntegerType *ITy = cast<IntegerType>(getEffectiveSCEVType(Ty)); |
| 334 | return getConstant(ConstantInt::get(ITy, V, isSigned)); |
| 335 | } |
| 336 | |
| 337 | SCEVCastExpr::SCEVCastExpr(const FoldingSetNodeIDRef ID, |
| 338 | unsigned SCEVTy, const SCEV *op, Type *ty) |
| 339 | : SCEV(ID, SCEVTy), Op(op), Ty(ty) {} |
| 340 | |
| 341 | SCEVTruncateExpr::SCEVTruncateExpr(const FoldingSetNodeIDRef ID, |
| 342 | const SCEV *op, Type *ty) |
| 343 | : SCEVCastExpr(ID, scTruncate, op, ty) { |
| 344 | assert((Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) &&(((Op->getType()->isIntegerTy() || Op->getType()-> isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy ()) && "Cannot truncate non-integer value!") ? static_cast <void> (0) : __assert_fail ("(Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot truncate non-integer value!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 346, __PRETTY_FUNCTION__)) |
| 345 | (Ty->isIntegerTy() || Ty->isPointerTy()) &&(((Op->getType()->isIntegerTy() || Op->getType()-> isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy ()) && "Cannot truncate non-integer value!") ? static_cast <void> (0) : __assert_fail ("(Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot truncate non-integer value!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 346, __PRETTY_FUNCTION__)) |
| 346 | "Cannot truncate non-integer value!")(((Op->getType()->isIntegerTy() || Op->getType()-> isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy ()) && "Cannot truncate non-integer value!") ? static_cast <void> (0) : __assert_fail ("(Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot truncate non-integer value!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 346, __PRETTY_FUNCTION__)); |
| 347 | } |
| 348 | |
| 349 | SCEVZeroExtendExpr::SCEVZeroExtendExpr(const FoldingSetNodeIDRef ID, |
| 350 | const SCEV *op, Type *ty) |
| 351 | : SCEVCastExpr(ID, scZeroExtend, op, ty) { |
| 352 | assert((Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) &&(((Op->getType()->isIntegerTy() || Op->getType()-> isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy ()) && "Cannot zero extend non-integer value!") ? static_cast <void> (0) : __assert_fail ("(Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot zero extend non-integer value!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 354, __PRETTY_FUNCTION__)) |
| 353 | (Ty->isIntegerTy() || Ty->isPointerTy()) &&(((Op->getType()->isIntegerTy() || Op->getType()-> isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy ()) && "Cannot zero extend non-integer value!") ? static_cast <void> (0) : __assert_fail ("(Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot zero extend non-integer value!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 354, __PRETTY_FUNCTION__)) |
| 354 | "Cannot zero extend non-integer value!")(((Op->getType()->isIntegerTy() || Op->getType()-> isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy ()) && "Cannot zero extend non-integer value!") ? static_cast <void> (0) : __assert_fail ("(Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot zero extend non-integer value!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 354, __PRETTY_FUNCTION__)); |
| 355 | } |
| 356 | |
| 357 | SCEVSignExtendExpr::SCEVSignExtendExpr(const FoldingSetNodeIDRef ID, |
| 358 | const SCEV *op, Type *ty) |
| 359 | : SCEVCastExpr(ID, scSignExtend, op, ty) { |
| 360 | assert((Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) &&(((Op->getType()->isIntegerTy() || Op->getType()-> isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy ()) && "Cannot sign extend non-integer value!") ? static_cast <void> (0) : __assert_fail ("(Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot sign extend non-integer value!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 362, __PRETTY_FUNCTION__)) |
| 361 | (Ty->isIntegerTy() || Ty->isPointerTy()) &&(((Op->getType()->isIntegerTy() || Op->getType()-> isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy ()) && "Cannot sign extend non-integer value!") ? static_cast <void> (0) : __assert_fail ("(Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot sign extend non-integer value!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 362, __PRETTY_FUNCTION__)) |
| 362 | "Cannot sign extend non-integer value!")(((Op->getType()->isIntegerTy() || Op->getType()-> isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy ()) && "Cannot sign extend non-integer value!") ? static_cast <void> (0) : __assert_fail ("(Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot sign extend non-integer value!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 362, __PRETTY_FUNCTION__)); |
| 363 | } |
| 364 | |
| 365 | void SCEVUnknown::deleted() { |
| 366 | // Clear this SCEVUnknown from various maps. |
| 367 | SE->forgetMemoizedResults(this); |
| 368 | |
| 369 | // Remove this SCEVUnknown from the uniquing map. |
| 370 | SE->UniqueSCEVs.RemoveNode(this); |
| 371 | |
| 372 | // Release the value. |
| 373 | setValPtr(nullptr); |
| 374 | } |
| 375 | |
| 376 | void SCEVUnknown::allUsesReplacedWith(Value *New) { |
| 377 | // Clear this SCEVUnknown from various maps. |
| 378 | SE->forgetMemoizedResults(this); |
| 379 | |
| 380 | // Remove this SCEVUnknown from the uniquing map. |
| 381 | SE->UniqueSCEVs.RemoveNode(this); |
| 382 | |
| 383 | // Update this SCEVUnknown to point to the new value. This is needed |
| 384 | // because there may still be outstanding SCEVs which still point to |
| 385 | // this SCEVUnknown. |
| 386 | setValPtr(New); |
| 387 | } |
| 388 | |
| 389 | bool SCEVUnknown::isSizeOf(Type *&AllocTy) const { |
| 390 | if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(getValue())) |
| 391 | if (VCE->getOpcode() == Instruction::PtrToInt) |
| 392 | if (ConstantExpr *CE = dyn_cast<ConstantExpr>(VCE->getOperand(0))) |
| 393 | if (CE->getOpcode() == Instruction::GetElementPtr && |
| 394 | CE->getOperand(0)->isNullValue() && |
| 395 | CE->getNumOperands() == 2) |
| 396 | if (ConstantInt *CI = dyn_cast<ConstantInt>(CE->getOperand(1))) |
| 397 | if (CI->isOne()) { |
| 398 | AllocTy = cast<PointerType>(CE->getOperand(0)->getType()) |
| 399 | ->getElementType(); |
| 400 | return true; |
| 401 | } |
| 402 | |
| 403 | return false; |
| 404 | } |
| 405 | |
| 406 | bool SCEVUnknown::isAlignOf(Type *&AllocTy) const { |
| 407 | if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(getValue())) |
| 408 | if (VCE->getOpcode() == Instruction::PtrToInt) |
| 409 | if (ConstantExpr *CE = dyn_cast<ConstantExpr>(VCE->getOperand(0))) |
| 410 | if (CE->getOpcode() == Instruction::GetElementPtr && |
| 411 | CE->getOperand(0)->isNullValue()) { |
| 412 | Type *Ty = |
| 413 | cast<PointerType>(CE->getOperand(0)->getType())->getElementType(); |
| 414 | if (StructType *STy = dyn_cast<StructType>(Ty)) |
| 415 | if (!STy->isPacked() && |
| 416 | CE->getNumOperands() == 3 && |
| 417 | CE->getOperand(1)->isNullValue()) { |
| 418 | if (ConstantInt *CI = dyn_cast<ConstantInt>(CE->getOperand(2))) |
| 419 | if (CI->isOne() && |
| 420 | STy->getNumElements() == 2 && |
| 421 | STy->getElementType(0)->isIntegerTy(1)) { |
| 422 | AllocTy = STy->getElementType(1); |
| 423 | return true; |
| 424 | } |
| 425 | } |
| 426 | } |
| 427 | |
| 428 | return false; |
| 429 | } |
| 430 | |
| 431 | bool SCEVUnknown::isOffsetOf(Type *&CTy, Constant *&FieldNo) const { |
| 432 | if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(getValue())) |
| 433 | if (VCE->getOpcode() == Instruction::PtrToInt) |
| 434 | if (ConstantExpr *CE = dyn_cast<ConstantExpr>(VCE->getOperand(0))) |
| 435 | if (CE->getOpcode() == Instruction::GetElementPtr && |
| 436 | CE->getNumOperands() == 3 && |
| 437 | CE->getOperand(0)->isNullValue() && |
| 438 | CE->getOperand(1)->isNullValue()) { |
| 439 | Type *Ty = |
| 440 | cast<PointerType>(CE->getOperand(0)->getType())->getElementType(); |
| 441 | // Ignore vector types here so that ScalarEvolutionExpander doesn't |
| 442 | // emit getelementptrs that index into vectors. |
| 443 | if (Ty->isStructTy() || Ty->isArrayTy()) { |
| 444 | CTy = Ty; |
| 445 | FieldNo = CE->getOperand(2); |
| 446 | return true; |
| 447 | } |
| 448 | } |
| 449 | |
| 450 | return false; |
| 451 | } |
| 452 | |
| 453 | //===----------------------------------------------------------------------===// |
| 454 | // SCEV Utilities |
| 455 | //===----------------------------------------------------------------------===// |
| 456 | |
| 457 | namespace { |
| 458 | /// SCEVComplexityCompare - Return true if the complexity of the LHS is less |
| 459 | /// than the complexity of the RHS. This comparator is used to canonicalize |
| 460 | /// expressions. |
| 461 | class SCEVComplexityCompare { |
| 462 | const LoopInfo *const LI; |
| 463 | public: |
| 464 | explicit SCEVComplexityCompare(const LoopInfo *li) : LI(li) {} |
| 465 | |
| 466 | // Return true or false if LHS is less than, or at least RHS, respectively. |
| 467 | bool operator()(const SCEV *LHS, const SCEV *RHS) const { |
| 468 | return compare(LHS, RHS) < 0; |
| 469 | } |
| 470 | |
| 471 | // Return negative, zero, or positive, if LHS is less than, equal to, or |
| 472 | // greater than RHS, respectively. A three-way result allows recursive |
| 473 | // comparisons to be more efficient. |
| 474 | int compare(const SCEV *LHS, const SCEV *RHS) const { |
| 475 | // Fast-path: SCEVs are uniqued so we can do a quick equality check. |
| 476 | if (LHS == RHS) |
| 477 | return 0; |
| 478 | |
| 479 | // Primarily, sort the SCEVs by their getSCEVType(). |
| 480 | unsigned LType = LHS->getSCEVType(), RType = RHS->getSCEVType(); |
| 481 | if (LType != RType) |
| 482 | return (int)LType - (int)RType; |
| 483 | |
| 484 | // Aside from the getSCEVType() ordering, the particular ordering |
| 485 | // isn't very important except that it's beneficial to be consistent, |
| 486 | // so that (a + b) and (b + a) don't end up as different expressions. |
| 487 | switch (static_cast<SCEVTypes>(LType)) { |
| 488 | case scUnknown: { |
| 489 | const SCEVUnknown *LU = cast<SCEVUnknown>(LHS); |
| 490 | const SCEVUnknown *RU = cast<SCEVUnknown>(RHS); |
| 491 | |
| 492 | // Sort SCEVUnknown values with some loose heuristics. TODO: This is |
| 493 | // not as complete as it could be. |
| 494 | const Value *LV = LU->getValue(), *RV = RU->getValue(); |
| 495 | |
| 496 | // Order pointer values after integer values. This helps SCEVExpander |
| 497 | // form GEPs. |
| 498 | bool LIsPointer = LV->getType()->isPointerTy(), |
| 499 | RIsPointer = RV->getType()->isPointerTy(); |
| 500 | if (LIsPointer != RIsPointer) |
| 501 | return (int)LIsPointer - (int)RIsPointer; |
| 502 | |
| 503 | // Compare getValueID values. |
| 504 | unsigned LID = LV->getValueID(), |
| 505 | RID = RV->getValueID(); |
| 506 | if (LID != RID) |
| 507 | return (int)LID - (int)RID; |
| 508 | |
| 509 | // Sort arguments by their position. |
| 510 | if (const Argument *LA = dyn_cast<Argument>(LV)) { |
| 511 | const Argument *RA = cast<Argument>(RV); |
| 512 | unsigned LArgNo = LA->getArgNo(), RArgNo = RA->getArgNo(); |
| 513 | return (int)LArgNo - (int)RArgNo; |
| 514 | } |
| 515 | |
| 516 | // For instructions, compare their loop depth, and their operand |
| 517 | // count. This is pretty loose. |
| 518 | if (const Instruction *LInst = dyn_cast<Instruction>(LV)) { |
| 519 | const Instruction *RInst = cast<Instruction>(RV); |
| 520 | |
| 521 | // Compare loop depths. |
| 522 | const BasicBlock *LParent = LInst->getParent(), |
| 523 | *RParent = RInst->getParent(); |
| 524 | if (LParent != RParent) { |
| 525 | unsigned LDepth = LI->getLoopDepth(LParent), |
| 526 | RDepth = LI->getLoopDepth(RParent); |
| 527 | if (LDepth != RDepth) |
| 528 | return (int)LDepth - (int)RDepth; |
| 529 | } |
| 530 | |
| 531 | // Compare the number of operands. |
| 532 | unsigned LNumOps = LInst->getNumOperands(), |
| 533 | RNumOps = RInst->getNumOperands(); |
| 534 | return (int)LNumOps - (int)RNumOps; |
| 535 | } |
| 536 | |
| 537 | return 0; |
| 538 | } |
| 539 | |
| 540 | case scConstant: { |
| 541 | const SCEVConstant *LC = cast<SCEVConstant>(LHS); |
| 542 | const SCEVConstant *RC = cast<SCEVConstant>(RHS); |
| 543 | |
| 544 | // Compare constant values. |
| 545 | const APInt &LA = LC->getValue()->getValue(); |
| 546 | const APInt &RA = RC->getValue()->getValue(); |
| 547 | unsigned LBitWidth = LA.getBitWidth(), RBitWidth = RA.getBitWidth(); |
| 548 | if (LBitWidth != RBitWidth) |
| 549 | return (int)LBitWidth - (int)RBitWidth; |
| 550 | return LA.ult(RA) ? -1 : 1; |
| 551 | } |
| 552 | |
| 553 | case scAddRecExpr: { |
| 554 | const SCEVAddRecExpr *LA = cast<SCEVAddRecExpr>(LHS); |
| 555 | const SCEVAddRecExpr *RA = cast<SCEVAddRecExpr>(RHS); |
| 556 | |
| 557 | // Compare addrec loop depths. |
| 558 | const Loop *LLoop = LA->getLoop(), *RLoop = RA->getLoop(); |
| 559 | if (LLoop != RLoop) { |
| 560 | unsigned LDepth = LLoop->getLoopDepth(), |
| 561 | RDepth = RLoop->getLoopDepth(); |
| 562 | if (LDepth != RDepth) |
| 563 | return (int)LDepth - (int)RDepth; |
| 564 | } |
| 565 | |
| 566 | // Addrec complexity grows with operand count. |
| 567 | unsigned LNumOps = LA->getNumOperands(), RNumOps = RA->getNumOperands(); |
| 568 | if (LNumOps != RNumOps) |
| 569 | return (int)LNumOps - (int)RNumOps; |
| 570 | |
| 571 | // Lexicographically compare. |
| 572 | for (unsigned i = 0; i != LNumOps; ++i) { |
| 573 | long X = compare(LA->getOperand(i), RA->getOperand(i)); |
| 574 | if (X != 0) |
| 575 | return X; |
| 576 | } |
| 577 | |
| 578 | return 0; |
| 579 | } |
| 580 | |
| 581 | case scAddExpr: |
| 582 | case scMulExpr: |
| 583 | case scSMaxExpr: |
| 584 | case scUMaxExpr: { |
| 585 | const SCEVNAryExpr *LC = cast<SCEVNAryExpr>(LHS); |
| 586 | const SCEVNAryExpr *RC = cast<SCEVNAryExpr>(RHS); |
| 587 | |
| 588 | // Lexicographically compare n-ary expressions. |
| 589 | unsigned LNumOps = LC->getNumOperands(), RNumOps = RC->getNumOperands(); |
| 590 | if (LNumOps != RNumOps) |
| 591 | return (int)LNumOps - (int)RNumOps; |
| 592 | |
| 593 | for (unsigned i = 0; i != LNumOps; ++i) { |
| 594 | if (i >= RNumOps) |
| 595 | return 1; |
| 596 | long X = compare(LC->getOperand(i), RC->getOperand(i)); |
| 597 | if (X != 0) |
| 598 | return X; |
| 599 | } |
| 600 | return (int)LNumOps - (int)RNumOps; |
| 601 | } |
| 602 | |
| 603 | case scUDivExpr: { |
| 604 | const SCEVUDivExpr *LC = cast<SCEVUDivExpr>(LHS); |
| 605 | const SCEVUDivExpr *RC = cast<SCEVUDivExpr>(RHS); |
| 606 | |
| 607 | // Lexicographically compare udiv expressions. |
| 608 | long X = compare(LC->getLHS(), RC->getLHS()); |
| 609 | if (X != 0) |
| 610 | return X; |
| 611 | return compare(LC->getRHS(), RC->getRHS()); |
| 612 | } |
| 613 | |
| 614 | case scTruncate: |
| 615 | case scZeroExtend: |
| 616 | case scSignExtend: { |
| 617 | const SCEVCastExpr *LC = cast<SCEVCastExpr>(LHS); |
| 618 | const SCEVCastExpr *RC = cast<SCEVCastExpr>(RHS); |
| 619 | |
| 620 | // Compare cast expressions by operand. |
| 621 | return compare(LC->getOperand(), RC->getOperand()); |
| 622 | } |
| 623 | |
| 624 | case scCouldNotCompute: |
| 625 | llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!")::llvm::llvm_unreachable_internal("Attempt to use a SCEVCouldNotCompute object!" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 625); |
| 626 | } |
| 627 | llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 627); |
| 628 | } |
| 629 | }; |
| 630 | } |
| 631 | |
| 632 | /// GroupByComplexity - Given a list of SCEV objects, order them by their |
| 633 | /// complexity, and group objects of the same complexity together by value. |
| 634 | /// When this routine is finished, we know that any duplicates in the vector are |
| 635 | /// consecutive and that complexity is monotonically increasing. |
| 636 | /// |
| 637 | /// Note that we go take special precautions to ensure that we get deterministic |
| 638 | /// results from this routine. In other words, we don't want the results of |
| 639 | /// this to depend on where the addresses of various SCEV objects happened to |
| 640 | /// land in memory. |
| 641 | /// |
| 642 | static void GroupByComplexity(SmallVectorImpl<const SCEV *> &Ops, |
| 643 | LoopInfo *LI) { |
| 644 | if (Ops.size() < 2) return; // Noop |
| 645 | if (Ops.size() == 2) { |
| 646 | // This is the common case, which also happens to be trivially simple. |
| 647 | // Special case it. |
| 648 | const SCEV *&LHS = Ops[0], *&RHS = Ops[1]; |
| 649 | if (SCEVComplexityCompare(LI)(RHS, LHS)) |
| 650 | std::swap(LHS, RHS); |
| 651 | return; |
| 652 | } |
| 653 | |
| 654 | // Do the rough sort by complexity. |
| 655 | std::stable_sort(Ops.begin(), Ops.end(), SCEVComplexityCompare(LI)); |
| 656 | |
| 657 | // Now that we are sorted by complexity, group elements of the same |
| 658 | // complexity. Note that this is, at worst, N^2, but the vector is likely to |
| 659 | // be extremely short in practice. Note that we take this approach because we |
| 660 | // do not want to depend on the addresses of the objects we are grouping. |
| 661 | for (unsigned i = 0, e = Ops.size(); i != e-2; ++i) { |
| 662 | const SCEV *S = Ops[i]; |
| 663 | unsigned Complexity = S->getSCEVType(); |
| 664 | |
| 665 | // If there are any objects of the same complexity and same value as this |
| 666 | // one, group them. |
| 667 | for (unsigned j = i+1; j != e && Ops[j]->getSCEVType() == Complexity; ++j) { |
| 668 | if (Ops[j] == S) { // Found a duplicate. |
| 669 | // Move it to immediately after i'th element. |
| 670 | std::swap(Ops[i+1], Ops[j]); |
| 671 | ++i; // no need to rescan it. |
| 672 | if (i == e-2) return; // Done! |
| 673 | } |
| 674 | } |
| 675 | } |
| 676 | } |
| 677 | |
| 678 | static const APInt srem(const SCEVConstant *C1, const SCEVConstant *C2) { |
| 679 | APInt A = C1->getValue()->getValue(); |
| 680 | APInt B = C2->getValue()->getValue(); |
| 681 | uint32_t ABW = A.getBitWidth(); |
| 682 | uint32_t BBW = B.getBitWidth(); |
| 683 | |
| 684 | if (ABW > BBW) |
| 685 | B = B.sext(ABW); |
| 686 | else if (ABW < BBW) |
| 687 | A = A.sext(BBW); |
| 688 | |
| 689 | return APIntOps::srem(A, B); |
| 690 | } |
| 691 | |
| 692 | static const APInt sdiv(const SCEVConstant *C1, const SCEVConstant *C2) { |
| 693 | APInt A = C1->getValue()->getValue(); |
| 694 | APInt B = C2->getValue()->getValue(); |
| 695 | uint32_t ABW = A.getBitWidth(); |
| 696 | uint32_t BBW = B.getBitWidth(); |
| 697 | |
| 698 | if (ABW > BBW) |
| 699 | B = B.sext(ABW); |
| 700 | else if (ABW < BBW) |
| 701 | A = A.sext(BBW); |
| 702 | |
| 703 | return APIntOps::sdiv(A, B); |
| 704 | } |
| 705 | |
| 706 | namespace { |
| 707 | struct FindSCEVSize { |
| 708 | int Size; |
| 709 | FindSCEVSize() : Size(0) {} |
| 710 | |
| 711 | bool follow(const SCEV *S) { |
| 712 | ++Size; |
| 713 | // Keep looking at all operands of S. |
| 714 | return true; |
| 715 | } |
| 716 | bool isDone() const { |
| 717 | return false; |
| 718 | } |
| 719 | }; |
| 720 | } |
| 721 | |
| 722 | // Returns the size of the SCEV S. |
| 723 | static inline int sizeOfSCEV(const SCEV *S) { |
| 724 | FindSCEVSize F; |
| 725 | SCEVTraversal<FindSCEVSize> ST(F); |
| 726 | ST.visitAll(S); |
| 727 | return F.Size; |
| 728 | } |
| 729 | |
| 730 | namespace { |
| 731 | |
| 732 | struct SCEVDivision : public SCEVVisitor<SCEVDivision, void> { |
| 733 | public: |
| 734 | // Computes the Quotient and Remainder of the division of Numerator by |
| 735 | // Denominator. |
| 736 | static void divide(ScalarEvolution &SE, const SCEV *Numerator, |
| 737 | const SCEV *Denominator, const SCEV **Quotient, |
| 738 | const SCEV **Remainder) { |
| 739 | assert(Numerator && Denominator && "Uninitialized SCEV")((Numerator && Denominator && "Uninitialized SCEV" ) ? static_cast<void> (0) : __assert_fail ("Numerator && Denominator && \"Uninitialized SCEV\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 739, __PRETTY_FUNCTION__)); |
| 740 | |
| 741 | SCEVDivision D(SE, Numerator, Denominator); |
| 742 | |
| 743 | // Check for the trivial case here to avoid having to check for it in the |
| 744 | // rest of the code. |
| 745 | if (Numerator == Denominator) { |
| 746 | *Quotient = D.One; |
| 747 | *Remainder = D.Zero; |
| 748 | return; |
| 749 | } |
| 750 | |
| 751 | if (Numerator->isZero()) { |
| 752 | *Quotient = D.Zero; |
| 753 | *Remainder = D.Zero; |
| 754 | return; |
| 755 | } |
| 756 | |
| 757 | // Split the Denominator when it is a product. |
| 758 | if (const SCEVMulExpr *T = dyn_cast<const SCEVMulExpr>(Denominator)) { |
| 759 | const SCEV *Q, *R; |
| 760 | *Quotient = Numerator; |
| 761 | for (const SCEV *Op : T->operands()) { |
| 762 | divide(SE, *Quotient, Op, &Q, &R); |
| 763 | *Quotient = Q; |
| 764 | |
| 765 | // Bail out when the Numerator is not divisible by one of the terms of |
| 766 | // the Denominator. |
| 767 | if (!R->isZero()) { |
| 768 | *Quotient = D.Zero; |
| 769 | *Remainder = Numerator; |
| 770 | return; |
| 771 | } |
| 772 | } |
| 773 | *Remainder = D.Zero; |
| 774 | return; |
| 775 | } |
| 776 | |
| 777 | D.visit(Numerator); |
| 778 | *Quotient = D.Quotient; |
| 779 | *Remainder = D.Remainder; |
| 780 | } |
| 781 | |
| 782 | SCEVDivision(ScalarEvolution &S, const SCEV *Numerator, const SCEV *Denominator) |
| 783 | : SE(S), Denominator(Denominator) { |
| 784 | Zero = SE.getConstant(Denominator->getType(), 0); |
| 785 | One = SE.getConstant(Denominator->getType(), 1); |
| 786 | |
| 787 | // By default, we don't know how to divide Expr by Denominator. |
| 788 | // Providing the default here simplifies the rest of the code. |
| 789 | Quotient = Zero; |
| 790 | Remainder = Numerator; |
| 791 | } |
| 792 | |
| 793 | // Except in the trivial case described above, we do not know how to divide |
| 794 | // Expr by Denominator for the following functions with empty implementation. |
| 795 | void visitTruncateExpr(const SCEVTruncateExpr *Numerator) {} |
| 796 | void visitZeroExtendExpr(const SCEVZeroExtendExpr *Numerator) {} |
| 797 | void visitSignExtendExpr(const SCEVSignExtendExpr *Numerator) {} |
| 798 | void visitUDivExpr(const SCEVUDivExpr *Numerator) {} |
| 799 | void visitSMaxExpr(const SCEVSMaxExpr *Numerator) {} |
| 800 | void visitUMaxExpr(const SCEVUMaxExpr *Numerator) {} |
| 801 | void visitUnknown(const SCEVUnknown *Numerator) {} |
| 802 | void visitCouldNotCompute(const SCEVCouldNotCompute *Numerator) {} |
| 803 | |
| 804 | void visitConstant(const SCEVConstant *Numerator) { |
| 805 | if (const SCEVConstant *D = dyn_cast<SCEVConstant>(Denominator)) { |
| 806 | Quotient = SE.getConstant(sdiv(Numerator, D)); |
| 807 | Remainder = SE.getConstant(srem(Numerator, D)); |
| 808 | return; |
| 809 | } |
| 810 | } |
| 811 | |
| 812 | void visitAddRecExpr(const SCEVAddRecExpr *Numerator) { |
| 813 | const SCEV *StartQ, *StartR, *StepQ, *StepR; |
| 814 | assert(Numerator->isAffine() && "Numerator should be affine")((Numerator->isAffine() && "Numerator should be affine" ) ? static_cast<void> (0) : __assert_fail ("Numerator->isAffine() && \"Numerator should be affine\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 814, __PRETTY_FUNCTION__)); |
| 815 | divide(SE, Numerator->getStart(), Denominator, &StartQ, &StartR); |
| 816 | divide(SE, Numerator->getStepRecurrence(SE), Denominator, &StepQ, &StepR); |
| 817 | Quotient = SE.getAddRecExpr(StartQ, StepQ, Numerator->getLoop(), |
| 818 | Numerator->getNoWrapFlags()); |
| 819 | Remainder = SE.getAddRecExpr(StartR, StepR, Numerator->getLoop(), |
| 820 | Numerator->getNoWrapFlags()); |
| 821 | } |
| 822 | |
| 823 | void visitAddExpr(const SCEVAddExpr *Numerator) { |
| 824 | SmallVector<const SCEV *, 2> Qs, Rs; |
| 825 | Type *Ty = Denominator->getType(); |
| 826 | |
| 827 | for (const SCEV *Op : Numerator->operands()) { |
| 828 | const SCEV *Q, *R; |
| 829 | divide(SE, Op, Denominator, &Q, &R); |
| 830 | |
| 831 | // Bail out if types do not match. |
| 832 | if (Ty != Q->getType() || Ty != R->getType()) { |
| 833 | Quotient = Zero; |
| 834 | Remainder = Numerator; |
| 835 | return; |
| 836 | } |
| 837 | |
| 838 | Qs.push_back(Q); |
| 839 | Rs.push_back(R); |
| 840 | } |
| 841 | |
| 842 | if (Qs.size() == 1) { |
| 843 | Quotient = Qs[0]; |
| 844 | Remainder = Rs[0]; |
| 845 | return; |
| 846 | } |
| 847 | |
| 848 | Quotient = SE.getAddExpr(Qs); |
| 849 | Remainder = SE.getAddExpr(Rs); |
| 850 | } |
| 851 | |
| 852 | void visitMulExpr(const SCEVMulExpr *Numerator) { |
| 853 | SmallVector<const SCEV *, 2> Qs; |
| 854 | Type *Ty = Denominator->getType(); |
| 855 | |
| 856 | bool FoundDenominatorTerm = false; |
| 857 | for (const SCEV *Op : Numerator->operands()) { |
| 858 | // Bail out if types do not match. |
| 859 | if (Ty != Op->getType()) { |
| 860 | Quotient = Zero; |
| 861 | Remainder = Numerator; |
| 862 | return; |
| 863 | } |
| 864 | |
| 865 | if (FoundDenominatorTerm) { |
| 866 | Qs.push_back(Op); |
| 867 | continue; |
| 868 | } |
| 869 | |
| 870 | // Check whether Denominator divides one of the product operands. |
| 871 | const SCEV *Q, *R; |
| 872 | divide(SE, Op, Denominator, &Q, &R); |
| 873 | if (!R->isZero()) { |
| 874 | Qs.push_back(Op); |
| 875 | continue; |
| 876 | } |
| 877 | |
| 878 | // Bail out if types do not match. |
| 879 | if (Ty != Q->getType()) { |
| 880 | Quotient = Zero; |
| 881 | Remainder = Numerator; |
| 882 | return; |
| 883 | } |
| 884 | |
| 885 | FoundDenominatorTerm = true; |
| 886 | Qs.push_back(Q); |
| 887 | } |
| 888 | |
| 889 | if (FoundDenominatorTerm) { |
| 890 | Remainder = Zero; |
| 891 | if (Qs.size() == 1) |
| 892 | Quotient = Qs[0]; |
| 893 | else |
| 894 | Quotient = SE.getMulExpr(Qs); |
| 895 | return; |
| 896 | } |
| 897 | |
| 898 | if (!isa<SCEVUnknown>(Denominator)) { |
| 899 | Quotient = Zero; |
| 900 | Remainder = Numerator; |
| 901 | return; |
| 902 | } |
| 903 | |
| 904 | // The Remainder is obtained by replacing Denominator by 0 in Numerator. |
| 905 | ValueToValueMap RewriteMap; |
| 906 | RewriteMap[cast<SCEVUnknown>(Denominator)->getValue()] = |
| 907 | cast<SCEVConstant>(Zero)->getValue(); |
| 908 | Remainder = SCEVParameterRewriter::rewrite(Numerator, SE, RewriteMap, true); |
| 909 | |
| 910 | if (Remainder->isZero()) { |
| 911 | // The Quotient is obtained by replacing Denominator by 1 in Numerator. |
| 912 | RewriteMap[cast<SCEVUnknown>(Denominator)->getValue()] = |
| 913 | cast<SCEVConstant>(One)->getValue(); |
| 914 | Quotient = |
| 915 | SCEVParameterRewriter::rewrite(Numerator, SE, RewriteMap, true); |
| 916 | return; |
| 917 | } |
| 918 | |
| 919 | // Quotient is (Numerator - Remainder) divided by Denominator. |
| 920 | const SCEV *Q, *R; |
| 921 | const SCEV *Diff = SE.getMinusSCEV(Numerator, Remainder); |
| 922 | if (sizeOfSCEV(Diff) > sizeOfSCEV(Numerator)) { |
| 923 | // This SCEV does not seem to simplify: fail the division here. |
| 924 | Quotient = Zero; |
| 925 | Remainder = Numerator; |
| 926 | return; |
| 927 | } |
| 928 | divide(SE, Diff, Denominator, &Q, &R); |
| 929 | assert(R == Zero &&((R == Zero && "(Numerator - Remainder) should evenly divide Denominator" ) ? static_cast<void> (0) : __assert_fail ("R == Zero && \"(Numerator - Remainder) should evenly divide Denominator\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 930, __PRETTY_FUNCTION__)) |
| 930 | "(Numerator - Remainder) should evenly divide Denominator")((R == Zero && "(Numerator - Remainder) should evenly divide Denominator" ) ? static_cast<void> (0) : __assert_fail ("R == Zero && \"(Numerator - Remainder) should evenly divide Denominator\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 930, __PRETTY_FUNCTION__)); |
| 931 | Quotient = Q; |
| 932 | } |
| 933 | |
| 934 | private: |
| 935 | ScalarEvolution &SE; |
| 936 | const SCEV *Denominator, *Quotient, *Remainder, *Zero, *One; |
| 937 | }; |
| 938 | } |
| 939 | |
| 940 | |
| 941 | |
| 942 | //===----------------------------------------------------------------------===// |
| 943 | // Simple SCEV method implementations |
| 944 | //===----------------------------------------------------------------------===// |
| 945 | |
| 946 | /// BinomialCoefficient - Compute BC(It, K). The result has width W. |
| 947 | /// Assume, K > 0. |
| 948 | static const SCEV *BinomialCoefficient(const SCEV *It, unsigned K, |
| 949 | ScalarEvolution &SE, |
| 950 | Type *ResultTy) { |
| 951 | // Handle the simplest case efficiently. |
| 952 | if (K == 1) |
| 953 | return SE.getTruncateOrZeroExtend(It, ResultTy); |
| 954 | |
| 955 | // We are using the following formula for BC(It, K): |
| 956 | // |
| 957 | // BC(It, K) = (It * (It - 1) * ... * (It - K + 1)) / K! |
| 958 | // |
| 959 | // Suppose, W is the bitwidth of the return value. We must be prepared for |
| 960 | // overflow. Hence, we must assure that the result of our computation is |
| 961 | // equal to the accurate one modulo 2^W. Unfortunately, division isn't |
| 962 | // safe in modular arithmetic. |
| 963 | // |
| 964 | // However, this code doesn't use exactly that formula; the formula it uses |
| 965 | // is something like the following, where T is the number of factors of 2 in |
| 966 | // K! (i.e. trailing zeros in the binary representation of K!), and ^ is |
| 967 | // exponentiation: |
| 968 | // |
| 969 | // BC(It, K) = (It * (It - 1) * ... * (It - K + 1)) / 2^T / (K! / 2^T) |
| 970 | // |
| 971 | // This formula is trivially equivalent to the previous formula. However, |
| 972 | // this formula can be implemented much more efficiently. The trick is that |
| 973 | // K! / 2^T is odd, and exact division by an odd number *is* safe in modular |
| 974 | // arithmetic. To do exact division in modular arithmetic, all we have |
| 975 | // to do is multiply by the inverse. Therefore, this step can be done at |
| 976 | // width W. |
| 977 | // |
| 978 | // The next issue is how to safely do the division by 2^T. The way this |
| 979 | // is done is by doing the multiplication step at a width of at least W + T |
| 980 | // bits. This way, the bottom W+T bits of the product are accurate. Then, |
| 981 | // when we perform the division by 2^T (which is equivalent to a right shift |
| 982 | // by T), the bottom W bits are accurate. Extra bits are okay; they'll get |
| 983 | // truncated out after the division by 2^T. |
| 984 | // |
| 985 | // In comparison to just directly using the first formula, this technique |
| 986 | // is much more efficient; using the first formula requires W * K bits, |
| 987 | // but this formula less than W + K bits. Also, the first formula requires |
| 988 | // a division step, whereas this formula only requires multiplies and shifts. |
| 989 | // |
| 990 | // It doesn't matter whether the subtraction step is done in the calculation |
| 991 | // width or the input iteration count's width; if the subtraction overflows, |
| 992 | // the result must be zero anyway. We prefer here to do it in the width of |
| 993 | // the induction variable because it helps a lot for certain cases; CodeGen |
| 994 | // isn't smart enough to ignore the overflow, which leads to much less |
| 995 | // efficient code if the width of the subtraction is wider than the native |
| 996 | // register width. |
| 997 | // |
| 998 | // (It's possible to not widen at all by pulling out factors of 2 before |
| 999 | // the multiplication; for example, K=2 can be calculated as |
| 1000 | // It/2*(It+(It*INT_MIN/INT_MIN)+-1). However, it requires |
| 1001 | // extra arithmetic, so it's not an obvious win, and it gets |
| 1002 | // much more complicated for K > 3.) |
| 1003 | |
| 1004 | // Protection from insane SCEVs; this bound is conservative, |
| 1005 | // but it probably doesn't matter. |
| 1006 | if (K > 1000) |
| 1007 | return SE.getCouldNotCompute(); |
| 1008 | |
| 1009 | unsigned W = SE.getTypeSizeInBits(ResultTy); |
| 1010 | |
| 1011 | // Calculate K! / 2^T and T; we divide out the factors of two before |
| 1012 | // multiplying for calculating K! / 2^T to avoid overflow. |
| 1013 | // Other overflow doesn't matter because we only care about the bottom |
| 1014 | // W bits of the result. |
| 1015 | APInt OddFactorial(W, 1); |
| 1016 | unsigned T = 1; |
| 1017 | for (unsigned i = 3; i <= K; ++i) { |
| 1018 | APInt Mult(W, i); |
| 1019 | unsigned TwoFactors = Mult.countTrailingZeros(); |
| 1020 | T += TwoFactors; |
| 1021 | Mult = Mult.lshr(TwoFactors); |
| 1022 | OddFactorial *= Mult; |
| 1023 | } |
| 1024 | |
| 1025 | // We need at least W + T bits for the multiplication step |
| 1026 | unsigned CalculationBits = W + T; |
| 1027 | |
| 1028 | // Calculate 2^T, at width T+W. |
| 1029 | APInt DivFactor = APInt::getOneBitSet(CalculationBits, T); |
| 1030 | |
| 1031 | // Calculate the multiplicative inverse of K! / 2^T; |
| 1032 | // this multiplication factor will perform the exact division by |
| 1033 | // K! / 2^T. |
| 1034 | APInt Mod = APInt::getSignedMinValue(W+1); |
| 1035 | APInt MultiplyFactor = OddFactorial.zext(W+1); |
| 1036 | MultiplyFactor = MultiplyFactor.multiplicativeInverse(Mod); |
| 1037 | MultiplyFactor = MultiplyFactor.trunc(W); |
| 1038 | |
| 1039 | // Calculate the product, at width T+W |
| 1040 | IntegerType *CalculationTy = IntegerType::get(SE.getContext(), |
| 1041 | CalculationBits); |
| 1042 | const SCEV *Dividend = SE.getTruncateOrZeroExtend(It, CalculationTy); |
| 1043 | for (unsigned i = 1; i != K; ++i) { |
| 1044 | const SCEV *S = SE.getMinusSCEV(It, SE.getConstant(It->getType(), i)); |
| 1045 | Dividend = SE.getMulExpr(Dividend, |
| 1046 | SE.getTruncateOrZeroExtend(S, CalculationTy)); |
| 1047 | } |
| 1048 | |
| 1049 | // Divide by 2^T |
| 1050 | const SCEV *DivResult = SE.getUDivExpr(Dividend, SE.getConstant(DivFactor)); |
| 1051 | |
| 1052 | // Truncate the result, and divide by K! / 2^T. |
| 1053 | |
| 1054 | return SE.getMulExpr(SE.getConstant(MultiplyFactor), |
| 1055 | SE.getTruncateOrZeroExtend(DivResult, ResultTy)); |
| 1056 | } |
| 1057 | |
| 1058 | /// evaluateAtIteration - Return the value of this chain of recurrences at |
| 1059 | /// the specified iteration number. We can evaluate this recurrence by |
| 1060 | /// multiplying each element in the chain by the binomial coefficient |
| 1061 | /// corresponding to it. In other words, we can evaluate {A,+,B,+,C,+,D} as: |
| 1062 | /// |
| 1063 | /// A*BC(It, 0) + B*BC(It, 1) + C*BC(It, 2) + D*BC(It, 3) |
| 1064 | /// |
| 1065 | /// where BC(It, k) stands for binomial coefficient. |
| 1066 | /// |
| 1067 | const SCEV *SCEVAddRecExpr::evaluateAtIteration(const SCEV *It, |
| 1068 | ScalarEvolution &SE) const { |
| 1069 | const SCEV *Result = getStart(); |
| 1070 | for (unsigned i = 1, e = getNumOperands(); i != e; ++i) { |
| 1071 | // The computation is correct in the face of overflow provided that the |
| 1072 | // multiplication is performed _after_ the evaluation of the binomial |
| 1073 | // coefficient. |
| 1074 | const SCEV *Coeff = BinomialCoefficient(It, i, SE, getType()); |
| 1075 | if (isa<SCEVCouldNotCompute>(Coeff)) |
| 1076 | return Coeff; |
| 1077 | |
| 1078 | Result = SE.getAddExpr(Result, SE.getMulExpr(getOperand(i), Coeff)); |
| 1079 | } |
| 1080 | return Result; |
| 1081 | } |
| 1082 | |
| 1083 | //===----------------------------------------------------------------------===// |
| 1084 | // SCEV Expression folder implementations |
| 1085 | //===----------------------------------------------------------------------===// |
| 1086 | |
| 1087 | const SCEV *ScalarEvolution::getTruncateExpr(const SCEV *Op, |
| 1088 | Type *Ty) { |
| 1089 | assert(getTypeSizeInBits(Op->getType()) > getTypeSizeInBits(Ty) &&((getTypeSizeInBits(Op->getType()) > getTypeSizeInBits( Ty) && "This is not a truncating conversion!") ? static_cast <void> (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) > getTypeSizeInBits(Ty) && \"This is not a truncating conversion!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 1090, __PRETTY_FUNCTION__)) |
| 1090 | "This is not a truncating conversion!")((getTypeSizeInBits(Op->getType()) > getTypeSizeInBits( Ty) && "This is not a truncating conversion!") ? static_cast <void> (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) > getTypeSizeInBits(Ty) && \"This is not a truncating conversion!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 1090, __PRETTY_FUNCTION__)); |
| 1091 | assert(isSCEVable(Ty) &&((isSCEVable(Ty) && "This is not a conversion to a SCEVable type!" ) ? static_cast<void> (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 1092, __PRETTY_FUNCTION__)) |
| 1092 | "This is not a conversion to a SCEVable type!")((isSCEVable(Ty) && "This is not a conversion to a SCEVable type!" ) ? static_cast<void> (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 1092, __PRETTY_FUNCTION__)); |
| 1093 | Ty = getEffectiveSCEVType(Ty); |
| 1094 | |
| 1095 | FoldingSetNodeID ID; |
| 1096 | ID.AddInteger(scTruncate); |
| 1097 | ID.AddPointer(Op); |
| 1098 | ID.AddPointer(Ty); |
| 1099 | void *IP = nullptr; |
| 1100 | if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S; |
| 1101 | |
| 1102 | // Fold if the operand is constant. |
| 1103 | if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op)) |
| 1104 | return getConstant( |
| 1105 | cast<ConstantInt>(ConstantExpr::getTrunc(SC->getValue(), Ty))); |
| 1106 | |
| 1107 | // trunc(trunc(x)) --> trunc(x) |
| 1108 | if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op)) |
| 1109 | return getTruncateExpr(ST->getOperand(), Ty); |
| 1110 | |
| 1111 | // trunc(sext(x)) --> sext(x) if widening or trunc(x) if narrowing |
| 1112 | if (const SCEVSignExtendExpr *SS = dyn_cast<SCEVSignExtendExpr>(Op)) |
| 1113 | return getTruncateOrSignExtend(SS->getOperand(), Ty); |
| 1114 | |
| 1115 | // trunc(zext(x)) --> zext(x) if widening or trunc(x) if narrowing |
| 1116 | if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op)) |
| 1117 | return getTruncateOrZeroExtend(SZ->getOperand(), Ty); |
| 1118 | |
| 1119 | // trunc(x1+x2+...+xN) --> trunc(x1)+trunc(x2)+...+trunc(xN) if we can |
| 1120 | // eliminate all the truncates. |
| 1121 | if (const SCEVAddExpr *SA = dyn_cast<SCEVAddExpr>(Op)) { |
| 1122 | SmallVector<const SCEV *, 4> Operands; |
| 1123 | bool hasTrunc = false; |
| 1124 | for (unsigned i = 0, e = SA->getNumOperands(); i != e && !hasTrunc; ++i) { |
| 1125 | const SCEV *S = getTruncateExpr(SA->getOperand(i), Ty); |
| 1126 | hasTrunc = isa<SCEVTruncateExpr>(S); |
| 1127 | Operands.push_back(S); |
| 1128 | } |
| 1129 | if (!hasTrunc) |
| 1130 | return getAddExpr(Operands); |
| 1131 | UniqueSCEVs.FindNodeOrInsertPos(ID, IP); // Mutates IP, returns NULL. |
| 1132 | } |
| 1133 | |
| 1134 | // trunc(x1*x2*...*xN) --> trunc(x1)*trunc(x2)*...*trunc(xN) if we can |
| 1135 | // eliminate all the truncates. |
| 1136 | if (const SCEVMulExpr *SM = dyn_cast<SCEVMulExpr>(Op)) { |
| 1137 | SmallVector<const SCEV *, 4> Operands; |
| 1138 | bool hasTrunc = false; |
| 1139 | for (unsigned i = 0, e = SM->getNumOperands(); i != e && !hasTrunc; ++i) { |
| 1140 | const SCEV *S = getTruncateExpr(SM->getOperand(i), Ty); |
| 1141 | hasTrunc = isa<SCEVTruncateExpr>(S); |
| 1142 | Operands.push_back(S); |
| 1143 | } |
| 1144 | if (!hasTrunc) |
| 1145 | return getMulExpr(Operands); |
| 1146 | UniqueSCEVs.FindNodeOrInsertPos(ID, IP); // Mutates IP, returns NULL. |
| 1147 | } |
| 1148 | |
| 1149 | // If the input value is a chrec scev, truncate the chrec's operands. |
| 1150 | if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(Op)) { |
| 1151 | SmallVector<const SCEV *, 4> Operands; |
| 1152 | for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i) |
| 1153 | Operands.push_back(getTruncateExpr(AddRec->getOperand(i), Ty)); |
| 1154 | return getAddRecExpr(Operands, AddRec->getLoop(), SCEV::FlagAnyWrap); |
| 1155 | } |
| 1156 | |
| 1157 | // The cast wasn't folded; create an explicit cast node. We can reuse |
| 1158 | // the existing insert position since if we get here, we won't have |
| 1159 | // made any changes which would invalidate it. |
| 1160 | SCEV *S = new (SCEVAllocator) SCEVTruncateExpr(ID.Intern(SCEVAllocator), |
| 1161 | Op, Ty); |
| 1162 | UniqueSCEVs.InsertNode(S, IP); |
| 1163 | return S; |
| 1164 | } |
| 1165 | |
| 1166 | const SCEV *ScalarEvolution::getZeroExtendExpr(const SCEV *Op, |
| 1167 | Type *Ty) { |
| 1168 | assert(getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) &&((getTypeSizeInBits(Op->getType()) < getTypeSizeInBits( Ty) && "This is not an extending conversion!") ? static_cast <void> (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 1169, __PRETTY_FUNCTION__)) |
| 1169 | "This is not an extending conversion!")((getTypeSizeInBits(Op->getType()) < getTypeSizeInBits( Ty) && "This is not an extending conversion!") ? static_cast <void> (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 1169, __PRETTY_FUNCTION__)); |
| 1170 | assert(isSCEVable(Ty) &&((isSCEVable(Ty) && "This is not a conversion to a SCEVable type!" ) ? static_cast<void> (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 1171, __PRETTY_FUNCTION__)) |
| 1171 | "This is not a conversion to a SCEVable type!")((isSCEVable(Ty) && "This is not a conversion to a SCEVable type!" ) ? static_cast<void> (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 1171, __PRETTY_FUNCTION__)); |
| 1172 | Ty = getEffectiveSCEVType(Ty); |
| 1173 | |
| 1174 | // Fold if the operand is constant. |
| 1175 | if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op)) |
| 1176 | return getConstant( |
| 1177 | cast<ConstantInt>(ConstantExpr::getZExt(SC->getValue(), Ty))); |
| 1178 | |
| 1179 | // zext(zext(x)) --> zext(x) |
| 1180 | if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op)) |
| 1181 | return getZeroExtendExpr(SZ->getOperand(), Ty); |
| 1182 | |
| 1183 | // Before doing any expensive analysis, check to see if we've already |
| 1184 | // computed a SCEV for this Op and Ty. |
| 1185 | FoldingSetNodeID ID; |
| 1186 | ID.AddInteger(scZeroExtend); |
| 1187 | ID.AddPointer(Op); |
| 1188 | ID.AddPointer(Ty); |
| 1189 | void *IP = nullptr; |
| 1190 | if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S; |
| 1191 | |
| 1192 | // zext(trunc(x)) --> zext(x) or x or trunc(x) |
| 1193 | if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op)) { |
| 1194 | // It's possible the bits taken off by the truncate were all zero bits. If |
| 1195 | // so, we should be able to simplify this further. |
| 1196 | const SCEV *X = ST->getOperand(); |
| 1197 | ConstantRange CR = getUnsignedRange(X); |
| 1198 | unsigned TruncBits = getTypeSizeInBits(ST->getType()); |
| 1199 | unsigned NewBits = getTypeSizeInBits(Ty); |
| 1200 | if (CR.truncate(TruncBits).zeroExtend(NewBits).contains( |
| 1201 | CR.zextOrTrunc(NewBits))) |
| 1202 | return getTruncateOrZeroExtend(X, Ty); |
| 1203 | } |
| 1204 | |
| 1205 | // If the input value is a chrec scev, and we can prove that the value |
| 1206 | // did not overflow the old, smaller, value, we can zero extend all of the |
| 1207 | // operands (often constants). This allows analysis of something like |
| 1208 | // this: for (unsigned char X = 0; X < 100; ++X) { int Y = X; } |
| 1209 | if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op)) |
| 1210 | if (AR->isAffine()) { |
| 1211 | const SCEV *Start = AR->getStart(); |
| 1212 | const SCEV *Step = AR->getStepRecurrence(*this); |
| 1213 | unsigned BitWidth = getTypeSizeInBits(AR->getType()); |
| 1214 | const Loop *L = AR->getLoop(); |
| 1215 | |
| 1216 | // If we have special knowledge that this addrec won't overflow, |
| 1217 | // we don't need to do any further analysis. |
| 1218 | if (AR->getNoWrapFlags(SCEV::FlagNUW)) |
| 1219 | return getAddRecExpr(getZeroExtendExpr(Start, Ty), |
| 1220 | getZeroExtendExpr(Step, Ty), |
| 1221 | L, AR->getNoWrapFlags()); |
| 1222 | |
| 1223 | // Check whether the backedge-taken count is SCEVCouldNotCompute. |
| 1224 | // Note that this serves two purposes: It filters out loops that are |
| 1225 | // simply not analyzable, and it covers the case where this code is |
| 1226 | // being called from within backedge-taken count analysis, such that |
| 1227 | // attempting to ask for the backedge-taken count would likely result |
| 1228 | // in infinite recursion. In the later case, the analysis code will |
| 1229 | // cope with a conservative value, and it will take care to purge |
| 1230 | // that value once it has finished. |
| 1231 | const SCEV *MaxBECount = getMaxBackedgeTakenCount(L); |
| 1232 | if (!isa<SCEVCouldNotCompute>(MaxBECount)) { |
| 1233 | // Manually compute the final value for AR, checking for |
| 1234 | // overflow. |
| 1235 | |
| 1236 | // Check whether the backedge-taken count can be losslessly casted to |
| 1237 | // the addrec's type. The count is always unsigned. |
| 1238 | const SCEV *CastedMaxBECount = |
| 1239 | getTruncateOrZeroExtend(MaxBECount, Start->getType()); |
| 1240 | const SCEV *RecastedMaxBECount = |
| 1241 | getTruncateOrZeroExtend(CastedMaxBECount, MaxBECount->getType()); |
| 1242 | if (MaxBECount == RecastedMaxBECount) { |
| 1243 | Type *WideTy = IntegerType::get(getContext(), BitWidth * 2); |
| 1244 | // Check whether Start+Step*MaxBECount has no unsigned overflow. |
| 1245 | const SCEV *ZMul = getMulExpr(CastedMaxBECount, Step); |
| 1246 | const SCEV *ZAdd = getZeroExtendExpr(getAddExpr(Start, ZMul), WideTy); |
| 1247 | const SCEV *WideStart = getZeroExtendExpr(Start, WideTy); |
| 1248 | const SCEV *WideMaxBECount = |
| 1249 | getZeroExtendExpr(CastedMaxBECount, WideTy); |
| 1250 | const SCEV *OperandExtendedAdd = |
| 1251 | getAddExpr(WideStart, |
| 1252 | getMulExpr(WideMaxBECount, |
| 1253 | getZeroExtendExpr(Step, WideTy))); |
| 1254 | if (ZAdd == OperandExtendedAdd) { |
| 1255 | // Cache knowledge of AR NUW, which is propagated to this AddRec. |
| 1256 | const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNUW); |
| 1257 | // Return the expression with the addrec on the outside. |
| 1258 | return getAddRecExpr(getZeroExtendExpr(Start, Ty), |
| 1259 | getZeroExtendExpr(Step, Ty), |
| 1260 | L, AR->getNoWrapFlags()); |
| 1261 | } |
| 1262 | // Similar to above, only this time treat the step value as signed. |
| 1263 | // This covers loops that count down. |
| 1264 | OperandExtendedAdd = |
| 1265 | getAddExpr(WideStart, |
| 1266 | getMulExpr(WideMaxBECount, |
| 1267 | getSignExtendExpr(Step, WideTy))); |
| 1268 | if (ZAdd == OperandExtendedAdd) { |
| 1269 | // Cache knowledge of AR NW, which is propagated to this AddRec. |
| 1270 | // Negative step causes unsigned wrap, but it still can't self-wrap. |
| 1271 | const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNW); |
| 1272 | // Return the expression with the addrec on the outside. |
| 1273 | return getAddRecExpr(getZeroExtendExpr(Start, Ty), |
| 1274 | getSignExtendExpr(Step, Ty), |
| 1275 | L, AR->getNoWrapFlags()); |
| 1276 | } |
| 1277 | } |
| 1278 | |
| 1279 | // If the backedge is guarded by a comparison with the pre-inc value |
| 1280 | // the addrec is safe. Also, if the entry is guarded by a comparison |
| 1281 | // with the start value and the backedge is guarded by a comparison |
| 1282 | // with the post-inc value, the addrec is safe. |
| 1283 | if (isKnownPositive(Step)) { |
| 1284 | const SCEV *N = getConstant(APInt::getMinValue(BitWidth) - |
| 1285 | getUnsignedRange(Step).getUnsignedMax()); |
| 1286 | if (isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_ULT, AR, N) || |
| 1287 | (isLoopEntryGuardedByCond(L, ICmpInst::ICMP_ULT, Start, N) && |
| 1288 | isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_ULT, |
| 1289 | AR->getPostIncExpr(*this), N))) { |
| 1290 | // Cache knowledge of AR NUW, which is propagated to this AddRec. |
| 1291 | const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNUW); |
| 1292 | // Return the expression with the addrec on the outside. |
| 1293 | return getAddRecExpr(getZeroExtendExpr(Start, Ty), |
| 1294 | getZeroExtendExpr(Step, Ty), |
| 1295 | L, AR->getNoWrapFlags()); |
| 1296 | } |
| 1297 | } else if (isKnownNegative(Step)) { |
| 1298 | const SCEV *N = getConstant(APInt::getMaxValue(BitWidth) - |
| 1299 | getSignedRange(Step).getSignedMin()); |
| 1300 | if (isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_UGT, AR, N) || |
| 1301 | (isLoopEntryGuardedByCond(L, ICmpInst::ICMP_UGT, Start, N) && |
| 1302 | isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_UGT, |
| 1303 | AR->getPostIncExpr(*this), N))) { |
| 1304 | // Cache knowledge of AR NW, which is propagated to this AddRec. |
| 1305 | // Negative step causes unsigned wrap, but it still can't self-wrap. |
| 1306 | const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNW); |
| 1307 | // Return the expression with the addrec on the outside. |
| 1308 | return getAddRecExpr(getZeroExtendExpr(Start, Ty), |
| 1309 | getSignExtendExpr(Step, Ty), |
| 1310 | L, AR->getNoWrapFlags()); |
| 1311 | } |
| 1312 | } |
| 1313 | } |
| 1314 | } |
| 1315 | |
| 1316 | // The cast wasn't folded; create an explicit cast node. |
| 1317 | // Recompute the insert position, as it may have been invalidated. |
| 1318 | if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S; |
| 1319 | SCEV *S = new (SCEVAllocator) SCEVZeroExtendExpr(ID.Intern(SCEVAllocator), |
| 1320 | Op, Ty); |
| 1321 | UniqueSCEVs.InsertNode(S, IP); |
| 1322 | return S; |
| 1323 | } |
| 1324 | |
| 1325 | // Get the limit of a recurrence such that incrementing by Step cannot cause |
| 1326 | // signed overflow as long as the value of the recurrence within the loop does |
| 1327 | // not exceed this limit before incrementing. |
| 1328 | static const SCEV *getOverflowLimitForStep(const SCEV *Step, |
| 1329 | ICmpInst::Predicate *Pred, |
| 1330 | ScalarEvolution *SE) { |
| 1331 | unsigned BitWidth = SE->getTypeSizeInBits(Step->getType()); |
| 1332 | if (SE->isKnownPositive(Step)) { |
| 1333 | *Pred = ICmpInst::ICMP_SLT; |
| 1334 | return SE->getConstant(APInt::getSignedMinValue(BitWidth) - |
| 1335 | SE->getSignedRange(Step).getSignedMax()); |
| 1336 | } |
| 1337 | if (SE->isKnownNegative(Step)) { |
| 1338 | *Pred = ICmpInst::ICMP_SGT; |
| 1339 | return SE->getConstant(APInt::getSignedMaxValue(BitWidth) - |
| 1340 | SE->getSignedRange(Step).getSignedMin()); |
| 1341 | } |
| 1342 | return nullptr; |
| 1343 | } |
| 1344 | |
| 1345 | // The recurrence AR has been shown to have no signed wrap. Typically, if we can |
| 1346 | // prove NSW for AR, then we can just as easily prove NSW for its preincrement |
| 1347 | // or postincrement sibling. This allows normalizing a sign extended AddRec as |
| 1348 | // such: {sext(Step + Start),+,Step} => {(Step + sext(Start),+,Step} As a |
| 1349 | // result, the expression "Step + sext(PreIncAR)" is congruent with |
| 1350 | // "sext(PostIncAR)" |
| 1351 | static const SCEV *getPreStartForSignExtend(const SCEVAddRecExpr *AR, |
| 1352 | Type *Ty, |
| 1353 | ScalarEvolution *SE) { |
| 1354 | const Loop *L = AR->getLoop(); |
| 1355 | const SCEV *Start = AR->getStart(); |
| 1356 | const SCEV *Step = AR->getStepRecurrence(*SE); |
| 1357 | |
| 1358 | // Check for a simple looking step prior to loop entry. |
| 1359 | const SCEVAddExpr *SA = dyn_cast<SCEVAddExpr>(Start); |
| 1360 | if (!SA) |
| 1361 | return nullptr; |
| 1362 | |
| 1363 | // Create an AddExpr for "PreStart" after subtracting Step. Full SCEV |
| 1364 | // subtraction is expensive. For this purpose, perform a quick and dirty |
| 1365 | // difference, by checking for Step in the operand list. |
| 1366 | SmallVector<const SCEV *, 4> DiffOps; |
| 1367 | for (const SCEV *Op : SA->operands()) |
| 1368 | if (Op != Step) |
| 1369 | DiffOps.push_back(Op); |
| 1370 | |
| 1371 | if (DiffOps.size() == SA->getNumOperands()) |
| 1372 | return nullptr; |
| 1373 | |
| 1374 | // This is a postinc AR. Check for overflow on the preinc recurrence using the |
| 1375 | // same three conditions that getSignExtendedExpr checks. |
| 1376 | |
| 1377 | // 1. NSW flags on the step increment. |
| 1378 | const SCEV *PreStart = SE->getAddExpr(DiffOps, SA->getNoWrapFlags()); |
| 1379 | const SCEVAddRecExpr *PreAR = dyn_cast<SCEVAddRecExpr>( |
| 1380 | SE->getAddRecExpr(PreStart, Step, L, SCEV::FlagAnyWrap)); |
| 1381 | |
| 1382 | if (PreAR && PreAR->getNoWrapFlags(SCEV::FlagNSW)) |
| 1383 | return PreStart; |
| 1384 | |
| 1385 | // 2. Direct overflow check on the step operation's expression. |
| 1386 | unsigned BitWidth = SE->getTypeSizeInBits(AR->getType()); |
| 1387 | Type *WideTy = IntegerType::get(SE->getContext(), BitWidth * 2); |
| 1388 | const SCEV *OperandExtendedStart = |
| 1389 | SE->getAddExpr(SE->getSignExtendExpr(PreStart, WideTy), |
| 1390 | SE->getSignExtendExpr(Step, WideTy)); |
| 1391 | if (SE->getSignExtendExpr(Start, WideTy) == OperandExtendedStart) { |
| 1392 | // Cache knowledge of PreAR NSW. |
| 1393 | if (PreAR) |
| 1394 | const_cast<SCEVAddRecExpr *>(PreAR)->setNoWrapFlags(SCEV::FlagNSW); |
| 1395 | // FIXME: this optimization needs a unit test |
| 1396 | DEBUG(dbgs() << "SCEV: untested prestart overflow check\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { dbgs() << "SCEV: untested prestart overflow check\n" ; } } while (0); |
| 1397 | return PreStart; |
| 1398 | } |
| 1399 | |
| 1400 | // 3. Loop precondition. |
| 1401 | ICmpInst::Predicate Pred; |
| 1402 | const SCEV *OverflowLimit = getOverflowLimitForStep(Step, &Pred, SE); |
| 1403 | |
| 1404 | if (OverflowLimit && |
| 1405 | SE->isLoopEntryGuardedByCond(L, Pred, PreStart, OverflowLimit)) { |
| 1406 | return PreStart; |
| 1407 | } |
| 1408 | return nullptr; |
| 1409 | } |
| 1410 | |
| 1411 | // Get the normalized sign-extended expression for this AddRec's Start. |
| 1412 | static const SCEV *getSignExtendAddRecStart(const SCEVAddRecExpr *AR, |
| 1413 | Type *Ty, |
| 1414 | ScalarEvolution *SE) { |
| 1415 | const SCEV *PreStart = getPreStartForSignExtend(AR, Ty, SE); |
| 1416 | if (!PreStart) |
| 1417 | return SE->getSignExtendExpr(AR->getStart(), Ty); |
| 1418 | |
| 1419 | return SE->getAddExpr(SE->getSignExtendExpr(AR->getStepRecurrence(*SE), Ty), |
| 1420 | SE->getSignExtendExpr(PreStart, Ty)); |
| 1421 | } |
| 1422 | |
| 1423 | const SCEV *ScalarEvolution::getSignExtendExpr(const SCEV *Op, |
| 1424 | Type *Ty) { |
| 1425 | assert(getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) &&((getTypeSizeInBits(Op->getType()) < getTypeSizeInBits( Ty) && "This is not an extending conversion!") ? static_cast <void> (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 1426, __PRETTY_FUNCTION__)) |
| 1426 | "This is not an extending conversion!")((getTypeSizeInBits(Op->getType()) < getTypeSizeInBits( Ty) && "This is not an extending conversion!") ? static_cast <void> (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 1426, __PRETTY_FUNCTION__)); |
| 1427 | assert(isSCEVable(Ty) &&((isSCEVable(Ty) && "This is not a conversion to a SCEVable type!" ) ? static_cast<void> (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 1428, __PRETTY_FUNCTION__)) |
| 1428 | "This is not a conversion to a SCEVable type!")((isSCEVable(Ty) && "This is not a conversion to a SCEVable type!" ) ? static_cast<void> (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 1428, __PRETTY_FUNCTION__)); |
| 1429 | Ty = getEffectiveSCEVType(Ty); |
| 1430 | |
| 1431 | // Fold if the operand is constant. |
| 1432 | if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op)) |
| 1433 | return getConstant( |
| 1434 | cast<ConstantInt>(ConstantExpr::getSExt(SC->getValue(), Ty))); |
| 1435 | |
| 1436 | // sext(sext(x)) --> sext(x) |
| 1437 | if (const SCEVSignExtendExpr *SS = dyn_cast<SCEVSignExtendExpr>(Op)) |
| 1438 | return getSignExtendExpr(SS->getOperand(), Ty); |
| 1439 | |
| 1440 | // sext(zext(x)) --> zext(x) |
| 1441 | if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op)) |
| 1442 | return getZeroExtendExpr(SZ->getOperand(), Ty); |
| 1443 | |
| 1444 | // Before doing any expensive analysis, check to see if we've already |
| 1445 | // computed a SCEV for this Op and Ty. |
| 1446 | FoldingSetNodeID ID; |
| 1447 | ID.AddInteger(scSignExtend); |
| 1448 | ID.AddPointer(Op); |
| 1449 | ID.AddPointer(Ty); |
| 1450 | void *IP = nullptr; |
| 1451 | if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S; |
| 1452 | |
| 1453 | // If the input value is provably positive, build a zext instead. |
| 1454 | if (isKnownNonNegative(Op)) |
| 1455 | return getZeroExtendExpr(Op, Ty); |
| 1456 | |
| 1457 | // sext(trunc(x)) --> sext(x) or x or trunc(x) |
| 1458 | if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op)) { |
| 1459 | // It's possible the bits taken off by the truncate were all sign bits. If |
| 1460 | // so, we should be able to simplify this further. |
| 1461 | const SCEV *X = ST->getOperand(); |
| 1462 | ConstantRange CR = getSignedRange(X); |
| 1463 | unsigned TruncBits = getTypeSizeInBits(ST->getType()); |
| 1464 | unsigned NewBits = getTypeSizeInBits(Ty); |
| 1465 | if (CR.truncate(TruncBits).signExtend(NewBits).contains( |
| 1466 | CR.sextOrTrunc(NewBits))) |
| 1467 | return getTruncateOrSignExtend(X, Ty); |
| 1468 | } |
| 1469 | |
| 1470 | // sext(C1 + (C2 * x)) --> C1 + sext(C2 * x) if C1 < C2 |
| 1471 | if (auto SA = dyn_cast<SCEVAddExpr>(Op)) { |
| 1472 | if (SA->getNumOperands() == 2) { |
| 1473 | auto SC1 = dyn_cast<SCEVConstant>(SA->getOperand(0)); |
| 1474 | auto SMul = dyn_cast<SCEVMulExpr>(SA->getOperand(1)); |
| 1475 | if (SMul && SC1) { |
| 1476 | if (auto SC2 = dyn_cast<SCEVConstant>(SMul->getOperand(0))) { |
| 1477 | const APInt &C1 = SC1->getValue()->getValue(); |
| 1478 | const APInt &C2 = SC2->getValue()->getValue(); |
| 1479 | if (C1.isStrictlyPositive() && C2.isStrictlyPositive() && |
| 1480 | C2.ugt(C1) && C2.isPowerOf2()) |
| 1481 | return getAddExpr(getSignExtendExpr(SC1, Ty), |
| 1482 | getSignExtendExpr(SMul, Ty)); |
| 1483 | } |
| 1484 | } |
| 1485 | } |
| 1486 | } |
| 1487 | // If the input value is a chrec scev, and we can prove that the value |
| 1488 | // did not overflow the old, smaller, value, we can sign extend all of the |
| 1489 | // operands (often constants). This allows analysis of something like |
| 1490 | // this: for (signed char X = 0; X < 100; ++X) { int Y = X; } |
| 1491 | if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op)) |
| 1492 | if (AR->isAffine()) { |
| 1493 | const SCEV *Start = AR->getStart(); |
| 1494 | const SCEV *Step = AR->getStepRecurrence(*this); |
| 1495 | unsigned BitWidth = getTypeSizeInBits(AR->getType()); |
| 1496 | const Loop *L = AR->getLoop(); |
| 1497 | |
| 1498 | // If we have special knowledge that this addrec won't overflow, |
| 1499 | // we don't need to do any further analysis. |
| 1500 | if (AR->getNoWrapFlags(SCEV::FlagNSW)) |
| 1501 | return getAddRecExpr(getSignExtendAddRecStart(AR, Ty, this), |
| 1502 | getSignExtendExpr(Step, Ty), |
| 1503 | L, SCEV::FlagNSW); |
| 1504 | |
| 1505 | // Check whether the backedge-taken count is SCEVCouldNotCompute. |
| 1506 | // Note that this serves two purposes: It filters out loops that are |
| 1507 | // simply not analyzable, and it covers the case where this code is |
| 1508 | // being called from within backedge-taken count analysis, such that |
| 1509 | // attempting to ask for the backedge-taken count would likely result |
| 1510 | // in infinite recursion. In the later case, the analysis code will |
| 1511 | // cope with a conservative value, and it will take care to purge |
| 1512 | // that value once it has finished. |
| 1513 | const SCEV *MaxBECount = getMaxBackedgeTakenCount(L); |
| 1514 | if (!isa<SCEVCouldNotCompute>(MaxBECount)) { |
| 1515 | // Manually compute the final value for AR, checking for |
| 1516 | // overflow. |
| 1517 | |
| 1518 | // Check whether the backedge-taken count can be losslessly casted to |
| 1519 | // the addrec's type. The count is always unsigned. |
| 1520 | const SCEV *CastedMaxBECount = |
| 1521 | getTruncateOrZeroExtend(MaxBECount, Start->getType()); |
| 1522 | const SCEV *RecastedMaxBECount = |
| 1523 | getTruncateOrZeroExtend(CastedMaxBECount, MaxBECount->getType()); |
| 1524 | if (MaxBECount == RecastedMaxBECount) { |
| 1525 | Type *WideTy = IntegerType::get(getContext(), BitWidth * 2); |
| 1526 | // Check whether Start+Step*MaxBECount has no signed overflow. |
| 1527 | const SCEV *SMul = getMulExpr(CastedMaxBECount, Step); |
| 1528 | const SCEV *SAdd = getSignExtendExpr(getAddExpr(Start, SMul), WideTy); |
| 1529 | const SCEV *WideStart = getSignExtendExpr(Start, WideTy); |
| 1530 | const SCEV *WideMaxBECount = |
| 1531 | getZeroExtendExpr(CastedMaxBECount, WideTy); |
| 1532 | const SCEV *OperandExtendedAdd = |
| 1533 | getAddExpr(WideStart, |
| 1534 | getMulExpr(WideMaxBECount, |
| 1535 | getSignExtendExpr(Step, WideTy))); |
| 1536 | if (SAdd == OperandExtendedAdd) { |
| 1537 | // Cache knowledge of AR NSW, which is propagated to this AddRec. |
| 1538 | const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNSW); |
| 1539 | // Return the expression with the addrec on the outside. |
| 1540 | return getAddRecExpr(getSignExtendAddRecStart(AR, Ty, this), |
| 1541 | getSignExtendExpr(Step, Ty), |
| 1542 | L, AR->getNoWrapFlags()); |
| 1543 | } |
| 1544 | // Similar to above, only this time treat the step value as unsigned. |
| 1545 | // This covers loops that count up with an unsigned step. |
| 1546 | OperandExtendedAdd = |
| 1547 | getAddExpr(WideStart, |
| 1548 | getMulExpr(WideMaxBECount, |
| 1549 | getZeroExtendExpr(Step, WideTy))); |
| 1550 | if (SAdd == OperandExtendedAdd) { |
| 1551 | // Cache knowledge of AR NSW, which is propagated to this AddRec. |
| 1552 | const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNSW); |
| 1553 | // Return the expression with the addrec on the outside. |
| 1554 | return getAddRecExpr(getSignExtendAddRecStart(AR, Ty, this), |
| 1555 | getZeroExtendExpr(Step, Ty), |
| 1556 | L, AR->getNoWrapFlags()); |
| 1557 | } |
| 1558 | } |
| 1559 | |
| 1560 | // If the backedge is guarded by a comparison with the pre-inc value |
| 1561 | // the addrec is safe. Also, if the entry is guarded by a comparison |
| 1562 | // with the start value and the backedge is guarded by a comparison |
| 1563 | // with the post-inc value, the addrec is safe. |
| 1564 | ICmpInst::Predicate Pred; |
| 1565 | const SCEV *OverflowLimit = getOverflowLimitForStep(Step, &Pred, this); |
| 1566 | if (OverflowLimit && |
| 1567 | (isLoopBackedgeGuardedByCond(L, Pred, AR, OverflowLimit) || |
| 1568 | (isLoopEntryGuardedByCond(L, Pred, Start, OverflowLimit) && |
| 1569 | isLoopBackedgeGuardedByCond(L, Pred, AR->getPostIncExpr(*this), |
| 1570 | OverflowLimit)))) { |
| 1571 | // Cache knowledge of AR NSW, then propagate NSW to the wide AddRec. |
| 1572 | const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNSW); |
| 1573 | return getAddRecExpr(getSignExtendAddRecStart(AR, Ty, this), |
| 1574 | getSignExtendExpr(Step, Ty), |
| 1575 | L, AR->getNoWrapFlags()); |
| 1576 | } |
| 1577 | } |
| 1578 | // If Start and Step are constants, check if we can apply this |
| 1579 | // transformation: |
| 1580 | // sext{C1,+,C2} --> C1 + sext{0,+,C2} if C1 < C2 |
| 1581 | auto SC1 = dyn_cast<SCEVConstant>(Start); |
| 1582 | auto SC2 = dyn_cast<SCEVConstant>(Step); |
| 1583 | if (SC1 && SC2) { |
| 1584 | const APInt &C1 = SC1->getValue()->getValue(); |
| 1585 | const APInt &C2 = SC2->getValue()->getValue(); |
| 1586 | if (C1.isStrictlyPositive() && C2.isStrictlyPositive() && C2.ugt(C1) && |
| 1587 | C2.isPowerOf2()) { |
| 1588 | Start = getSignExtendExpr(Start, Ty); |
| 1589 | const SCEV *NewAR = getAddRecExpr(getConstant(AR->getType(), 0), Step, |
| 1590 | L, AR->getNoWrapFlags()); |
| 1591 | return getAddExpr(Start, getSignExtendExpr(NewAR, Ty)); |
| 1592 | } |
| 1593 | } |
| 1594 | } |
| 1595 | |
| 1596 | // The cast wasn't folded; create an explicit cast node. |
| 1597 | // Recompute the insert position, as it may have been invalidated. |
| 1598 | if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S; |
| 1599 | SCEV *S = new (SCEVAllocator) SCEVSignExtendExpr(ID.Intern(SCEVAllocator), |
| 1600 | Op, Ty); |
| 1601 | UniqueSCEVs.InsertNode(S, IP); |
| 1602 | return S; |
| 1603 | } |
| 1604 | |
| 1605 | /// getAnyExtendExpr - Return a SCEV for the given operand extended with |
| 1606 | /// unspecified bits out to the given type. |
| 1607 | /// |
| 1608 | const SCEV *ScalarEvolution::getAnyExtendExpr(const SCEV *Op, |
| 1609 | Type *Ty) { |
| 1610 | assert(getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) &&((getTypeSizeInBits(Op->getType()) < getTypeSizeInBits( Ty) && "This is not an extending conversion!") ? static_cast <void> (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 1611, __PRETTY_FUNCTION__)) |
| 1611 | "This is not an extending conversion!")((getTypeSizeInBits(Op->getType()) < getTypeSizeInBits( Ty) && "This is not an extending conversion!") ? static_cast <void> (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 1611, __PRETTY_FUNCTION__)); |
| 1612 | assert(isSCEVable(Ty) &&((isSCEVable(Ty) && "This is not a conversion to a SCEVable type!" ) ? static_cast<void> (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 1613, __PRETTY_FUNCTION__)) |
| 1613 | "This is not a conversion to a SCEVable type!")((isSCEVable(Ty) && "This is not a conversion to a SCEVable type!" ) ? static_cast<void> (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 1613, __PRETTY_FUNCTION__)); |
| 1614 | Ty = getEffectiveSCEVType(Ty); |
| 1615 | |
| 1616 | // Sign-extend negative constants. |
| 1617 | if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op)) |
| 1618 | if (SC->getValue()->getValue().isNegative()) |
| 1619 | return getSignExtendExpr(Op, Ty); |
| 1620 | |
| 1621 | // Peel off a truncate cast. |
| 1622 | if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(Op)) { |
| 1623 | const SCEV *NewOp = T->getOperand(); |
| 1624 | if (getTypeSizeInBits(NewOp->getType()) < getTypeSizeInBits(Ty)) |
| 1625 | return getAnyExtendExpr(NewOp, Ty); |
| 1626 | return getTruncateOrNoop(NewOp, Ty); |
| 1627 | } |
| 1628 | |
| 1629 | // Next try a zext cast. If the cast is folded, use it. |
| 1630 | const SCEV *ZExt = getZeroExtendExpr(Op, Ty); |
| 1631 | if (!isa<SCEVZeroExtendExpr>(ZExt)) |
| 1632 | return ZExt; |
| 1633 | |
| 1634 | // Next try a sext cast. If the cast is folded, use it. |
| 1635 | const SCEV *SExt = getSignExtendExpr(Op, Ty); |
| 1636 | if (!isa<SCEVSignExtendExpr>(SExt)) |
| 1637 | return SExt; |
| 1638 | |
| 1639 | // Force the cast to be folded into the operands of an addrec. |
| 1640 | if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op)) { |
| 1641 | SmallVector<const SCEV *, 4> Ops; |
| 1642 | for (const SCEV *Op : AR->operands()) |
| 1643 | Ops.push_back(getAnyExtendExpr(Op, Ty)); |
| 1644 | return getAddRecExpr(Ops, AR->getLoop(), SCEV::FlagNW); |
| 1645 | } |
| 1646 | |
| 1647 | // If the expression is obviously signed, use the sext cast value. |
| 1648 | if (isa<SCEVSMaxExpr>(Op)) |
| 1649 | return SExt; |
| 1650 | |
| 1651 | // Absent any other information, use the zext cast value. |
| 1652 | return ZExt; |
| 1653 | } |
| 1654 | |
| 1655 | /// CollectAddOperandsWithScales - Process the given Ops list, which is |
| 1656 | /// a list of operands to be added under the given scale, update the given |
| 1657 | /// map. This is a helper function for getAddRecExpr. As an example of |
| 1658 | /// what it does, given a sequence of operands that would form an add |
| 1659 | /// expression like this: |
| 1660 | /// |
| 1661 | /// m + n + 13 + (A * (o + p + (B * (q + m + 29)))) + r + (-1 * r) |
| 1662 | /// |
| 1663 | /// where A and B are constants, update the map with these values: |
| 1664 | /// |
| 1665 | /// (m, 1+A*B), (n, 1), (o, A), (p, A), (q, A*B), (r, 0) |
| 1666 | /// |
| 1667 | /// and add 13 + A*B*29 to AccumulatedConstant. |
| 1668 | /// This will allow getAddRecExpr to produce this: |
| 1669 | /// |
| 1670 | /// 13+A*B*29 + n + (m * (1+A*B)) + ((o + p) * A) + (q * A*B) |
| 1671 | /// |
| 1672 | /// This form often exposes folding opportunities that are hidden in |
| 1673 | /// the original operand list. |
| 1674 | /// |
| 1675 | /// Return true iff it appears that any interesting folding opportunities |
| 1676 | /// may be exposed. This helps getAddRecExpr short-circuit extra work in |
| 1677 | /// the common case where no interesting opportunities are present, and |
| 1678 | /// is also used as a check to avoid infinite recursion. |
| 1679 | /// |
| 1680 | static bool |
| 1681 | CollectAddOperandsWithScales(DenseMap<const SCEV *, APInt> &M, |
| 1682 | SmallVectorImpl<const SCEV *> &NewOps, |
| 1683 | APInt &AccumulatedConstant, |
| 1684 | const SCEV *const *Ops, size_t NumOperands, |
| 1685 | const APInt &Scale, |
| 1686 | ScalarEvolution &SE) { |
| 1687 | bool Interesting = false; |
| 1688 | |
| 1689 | // Iterate over the add operands. They are sorted, with constants first. |
| 1690 | unsigned i = 0; |
| 1691 | while (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[i])) { |
| 1692 | ++i; |
| 1693 | // Pull a buried constant out to the outside. |
| 1694 | if (Scale != 1 || AccumulatedConstant != 0 || C->getValue()->isZero()) |
| 1695 | Interesting = true; |
| 1696 | AccumulatedConstant += Scale * C->getValue()->getValue(); |
| 1697 | } |
| 1698 | |
| 1699 | // Next comes everything else. We're especially interested in multiplies |
| 1700 | // here, but they're in the middle, so just visit the rest with one loop. |
| 1701 | for (; i != NumOperands; ++i) { |
| 1702 | const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(Ops[i]); |
| 1703 | if (Mul && isa<SCEVConstant>(Mul->getOperand(0))) { |
| 1704 | APInt NewScale = |
| 1705 | Scale * cast<SCEVConstant>(Mul->getOperand(0))->getValue()->getValue(); |
| 1706 | if (Mul->getNumOperands() == 2 && isa<SCEVAddExpr>(Mul->getOperand(1))) { |
| 1707 | // A multiplication of a constant with another add; recurse. |
| 1708 | const SCEVAddExpr *Add = cast<SCEVAddExpr>(Mul->getOperand(1)); |
| 1709 | Interesting |= |
| 1710 | CollectAddOperandsWithScales(M, NewOps, AccumulatedConstant, |
| 1711 | Add->op_begin(), Add->getNumOperands(), |
| 1712 | NewScale, SE); |
| 1713 | } else { |
| 1714 | // A multiplication of a constant with some other value. Update |
| 1715 | // the map. |
| 1716 | SmallVector<const SCEV *, 4> MulOps(Mul->op_begin()+1, Mul->op_end()); |
| 1717 | const SCEV *Key = SE.getMulExpr(MulOps); |
| 1718 | std::pair<DenseMap<const SCEV *, APInt>::iterator, bool> Pair = |
| 1719 | M.insert(std::make_pair(Key, NewScale)); |
| 1720 | if (Pair.second) { |
| 1721 | NewOps.push_back(Pair.first->first); |
| 1722 | } else { |
| 1723 | Pair.first->second += NewScale; |
| 1724 | // The map already had an entry for this value, which may indicate |
| 1725 | // a folding opportunity. |
| 1726 | Interesting = true; |
| 1727 | } |
| 1728 | } |
| 1729 | } else { |
| 1730 | // An ordinary operand. Update the map. |
| 1731 | std::pair<DenseMap<const SCEV *, APInt>::iterator, bool> Pair = |
| 1732 | M.insert(std::make_pair(Ops[i], Scale)); |
| 1733 | if (Pair.second) { |
| 1734 | NewOps.push_back(Pair.first->first); |
| 1735 | } else { |
| 1736 | Pair.first->second += Scale; |
| 1737 | // The map already had an entry for this value, which may indicate |
| 1738 | // a folding opportunity. |
| 1739 | Interesting = true; |
| 1740 | } |
| 1741 | } |
| 1742 | } |
| 1743 | |
| 1744 | return Interesting; |
| 1745 | } |
| 1746 | |
| 1747 | namespace { |
| 1748 | struct APIntCompare { |
| 1749 | bool operator()(const APInt &LHS, const APInt &RHS) const { |
| 1750 | return LHS.ult(RHS); |
| 1751 | } |
| 1752 | }; |
| 1753 | } |
| 1754 | |
| 1755 | /// getAddExpr - Get a canonical add expression, or something simpler if |
| 1756 | /// possible. |
| 1757 | const SCEV *ScalarEvolution::getAddExpr(SmallVectorImpl<const SCEV *> &Ops, |
| 1758 | SCEV::NoWrapFlags Flags) { |
| 1759 | assert(!(Flags & ~(SCEV::FlagNUW | SCEV::FlagNSW)) &&((!(Flags & ~(SCEV::FlagNUW | SCEV::FlagNSW)) && "only nuw or nsw allowed" ) ? static_cast<void> (0) : __assert_fail ("!(Flags & ~(SCEV::FlagNUW | SCEV::FlagNSW)) && \"only nuw or nsw allowed\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 1760, __PRETTY_FUNCTION__)) |
| 1760 | "only nuw or nsw allowed")((!(Flags & ~(SCEV::FlagNUW | SCEV::FlagNSW)) && "only nuw or nsw allowed" ) ? static_cast<void> (0) : __assert_fail ("!(Flags & ~(SCEV::FlagNUW | SCEV::FlagNSW)) && \"only nuw or nsw allowed\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 1760, __PRETTY_FUNCTION__)); |
| 1761 | assert(!Ops.empty() && "Cannot get empty add!")((!Ops.empty() && "Cannot get empty add!") ? static_cast <void> (0) : __assert_fail ("!Ops.empty() && \"Cannot get empty add!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 1761, __PRETTY_FUNCTION__)); |
| 1762 | if (Ops.size() == 1) return Ops[0]; |
| 1763 | #ifndef NDEBUG |
| 1764 | Type *ETy = getEffectiveSCEVType(Ops[0]->getType()); |
| 1765 | for (unsigned i = 1, e = Ops.size(); i != e; ++i) |
| 1766 | assert(getEffectiveSCEVType(Ops[i]->getType()) == ETy &&((getEffectiveSCEVType(Ops[i]->getType()) == ETy && "SCEVAddExpr operand types don't match!") ? static_cast<void > (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVAddExpr operand types don't match!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 1767, __PRETTY_FUNCTION__)) |
| 1767 | "SCEVAddExpr operand types don't match!")((getEffectiveSCEVType(Ops[i]->getType()) == ETy && "SCEVAddExpr operand types don't match!") ? static_cast<void > (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVAddExpr operand types don't match!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 1767, __PRETTY_FUNCTION__)); |
| 1768 | #endif |
| 1769 | |
| 1770 | // If FlagNSW is true and all the operands are non-negative, infer FlagNUW. |
| 1771 | // And vice-versa. |
| 1772 | int SignOrUnsignMask = SCEV::FlagNUW | SCEV::FlagNSW; |
| 1773 | SCEV::NoWrapFlags SignOrUnsignWrap = maskFlags(Flags, SignOrUnsignMask); |
| 1774 | if (SignOrUnsignWrap && (SignOrUnsignWrap != SignOrUnsignMask)) { |
| 1775 | bool All = true; |
| 1776 | for (SmallVectorImpl<const SCEV *>::const_iterator I = Ops.begin(), |
| 1777 | E = Ops.end(); I != E; ++I) |
| 1778 | if (!isKnownNonNegative(*I)) { |
| 1779 | All = false; |
| 1780 | break; |
| 1781 | } |
| 1782 | if (All) Flags = setFlags(Flags, (SCEV::NoWrapFlags)SignOrUnsignMask); |
| 1783 | } |
| 1784 | |
| 1785 | // Sort by complexity, this groups all similar expression types together. |
| 1786 | GroupByComplexity(Ops, LI); |
| 1787 | |
| 1788 | // If there are any constants, fold them together. |
| 1789 | unsigned Idx = 0; |
| 1790 | if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) { |
| 1791 | ++Idx; |
| 1792 | assert(Idx < Ops.size())((Idx < Ops.size()) ? static_cast<void> (0) : __assert_fail ("Idx < Ops.size()", "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 1792, __PRETTY_FUNCTION__)); |
| 1793 | while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) { |
| 1794 | // We found two constants, fold them together! |
| 1795 | Ops[0] = getConstant(LHSC->getValue()->getValue() + |
| 1796 | RHSC->getValue()->getValue()); |
| 1797 | if (Ops.size() == 2) return Ops[0]; |
| 1798 | Ops.erase(Ops.begin()+1); // Erase the folded element |
| 1799 | LHSC = cast<SCEVConstant>(Ops[0]); |
| 1800 | } |
| 1801 | |
| 1802 | // If we are left with a constant zero being added, strip it off. |
| 1803 | if (LHSC->getValue()->isZero()) { |
| 1804 | Ops.erase(Ops.begin()); |
| 1805 | --Idx; |
| 1806 | } |
| 1807 | |
| 1808 | if (Ops.size() == 1) return Ops[0]; |
| 1809 | } |
| 1810 | |
| 1811 | // Okay, check to see if the same value occurs in the operand list more than |
| 1812 | // once. If so, merge them together into an multiply expression. Since we |
| 1813 | // sorted the list, these values are required to be adjacent. |
| 1814 | Type *Ty = Ops[0]->getType(); |
| 1815 | bool FoundMatch = false; |
| 1816 | for (unsigned i = 0, e = Ops.size(); i != e-1; ++i) |
| 1817 | if (Ops[i] == Ops[i+1]) { // X + Y + Y --> X + Y*2 |
| 1818 | // Scan ahead to count how many equal operands there are. |
| 1819 | unsigned Count = 2; |
| 1820 | while (i+Count != e && Ops[i+Count] == Ops[i]) |
| 1821 | ++Count; |
| 1822 | // Merge the values into a multiply. |
| 1823 | const SCEV *Scale = getConstant(Ty, Count); |
| 1824 | const SCEV *Mul = getMulExpr(Scale, Ops[i]); |
| 1825 | if (Ops.size() == Count) |
| 1826 | return Mul; |
| 1827 | Ops[i] = Mul; |
| 1828 | Ops.erase(Ops.begin()+i+1, Ops.begin()+i+Count); |
| 1829 | --i; e -= Count - 1; |
| 1830 | FoundMatch = true; |
| 1831 | } |
| 1832 | if (FoundMatch) |
| 1833 | return getAddExpr(Ops, Flags); |
| 1834 | |
| 1835 | // Check for truncates. If all the operands are truncated from the same |
| 1836 | // type, see if factoring out the truncate would permit the result to be |
| 1837 | // folded. eg., trunc(x) + m*trunc(n) --> trunc(x + trunc(m)*n) |
| 1838 | // if the contents of the resulting outer trunc fold to something simple. |
| 1839 | for (; Idx < Ops.size() && isa<SCEVTruncateExpr>(Ops[Idx]); ++Idx) { |
| 1840 | const SCEVTruncateExpr *Trunc = cast<SCEVTruncateExpr>(Ops[Idx]); |
| 1841 | Type *DstType = Trunc->getType(); |
| 1842 | Type *SrcType = Trunc->getOperand()->getType(); |
| 1843 | SmallVector<const SCEV *, 8> LargeOps; |
| 1844 | bool Ok = true; |
| 1845 | // Check all the operands to see if they can be represented in the |
| 1846 | // source type of the truncate. |
| 1847 | for (unsigned i = 0, e = Ops.size(); i != e; ++i) { |
| 1848 | if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(Ops[i])) { |
| 1849 | if (T->getOperand()->getType() != SrcType) { |
| 1850 | Ok = false; |
| 1851 | break; |
| 1852 | } |
| 1853 | LargeOps.push_back(T->getOperand()); |
| 1854 | } else if (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[i])) { |
| 1855 | LargeOps.push_back(getAnyExtendExpr(C, SrcType)); |
| 1856 | } else if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(Ops[i])) { |
| 1857 | SmallVector<const SCEV *, 8> LargeMulOps; |
| 1858 | for (unsigned j = 0, f = M->getNumOperands(); j != f && Ok; ++j) { |
| 1859 | if (const SCEVTruncateExpr *T = |
| 1860 | dyn_cast<SCEVTruncateExpr>(M->getOperand(j))) { |
| 1861 | if (T->getOperand()->getType() != SrcType) { |
| 1862 | Ok = false; |
| 1863 | break; |
| 1864 | } |
| 1865 | LargeMulOps.push_back(T->getOperand()); |
| 1866 | } else if (const SCEVConstant *C = |
| 1867 | dyn_cast<SCEVConstant>(M->getOperand(j))) { |
| 1868 | LargeMulOps.push_back(getAnyExtendExpr(C, SrcType)); |
| 1869 | } else { |
| 1870 | Ok = false; |
| 1871 | break; |
| 1872 | } |
| 1873 | } |
| 1874 | if (Ok) |
| 1875 | LargeOps.push_back(getMulExpr(LargeMulOps)); |
| 1876 | } else { |
| 1877 | Ok = false; |
| 1878 | break; |
| 1879 | } |
| 1880 | } |
| 1881 | if (Ok) { |
| 1882 | // Evaluate the expression in the larger type. |
| 1883 | const SCEV *Fold = getAddExpr(LargeOps, Flags); |
| 1884 | // If it folds to something simple, use it. Otherwise, don't. |
| 1885 | if (isa<SCEVConstant>(Fold) || isa<SCEVUnknown>(Fold)) |
| 1886 | return getTruncateExpr(Fold, DstType); |
| 1887 | } |
| 1888 | } |
| 1889 | |
| 1890 | // Skip past any other cast SCEVs. |
| 1891 | while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddExpr) |
| 1892 | ++Idx; |
| 1893 | |
| 1894 | // If there are add operands they would be next. |
| 1895 | if (Idx < Ops.size()) { |
| 1896 | bool DeletedAdd = false; |
| 1897 | while (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[Idx])) { |
| 1898 | // If we have an add, expand the add operands onto the end of the operands |
| 1899 | // list. |
| 1900 | Ops.erase(Ops.begin()+Idx); |
| 1901 | Ops.append(Add->op_begin(), Add->op_end()); |
| 1902 | DeletedAdd = true; |
| 1903 | } |
| 1904 | |
| 1905 | // If we deleted at least one add, we added operands to the end of the list, |
| 1906 | // and they are not necessarily sorted. Recurse to resort and resimplify |
| 1907 | // any operands we just acquired. |
| 1908 | if (DeletedAdd) |
| 1909 | return getAddExpr(Ops); |
| 1910 | } |
| 1911 | |
| 1912 | // Skip over the add expression until we get to a multiply. |
| 1913 | while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scMulExpr) |
| 1914 | ++Idx; |
| 1915 | |
| 1916 | // Check to see if there are any folding opportunities present with |
| 1917 | // operands multiplied by constant values. |
| 1918 | if (Idx < Ops.size() && isa<SCEVMulExpr>(Ops[Idx])) { |
| 1919 | uint64_t BitWidth = getTypeSizeInBits(Ty); |
| 1920 | DenseMap<const SCEV *, APInt> M; |
| 1921 | SmallVector<const SCEV *, 8> NewOps; |
| 1922 | APInt AccumulatedConstant(BitWidth, 0); |
| 1923 | if (CollectAddOperandsWithScales(M, NewOps, AccumulatedConstant, |
| 1924 | Ops.data(), Ops.size(), |
| 1925 | APInt(BitWidth, 1), *this)) { |
| 1926 | // Some interesting folding opportunity is present, so its worthwhile to |
| 1927 | // re-generate the operands list. Group the operands by constant scale, |
| 1928 | // to avoid multiplying by the same constant scale multiple times. |
| 1929 | std::map<APInt, SmallVector<const SCEV *, 4>, APIntCompare> MulOpLists; |
| 1930 | for (SmallVectorImpl<const SCEV *>::const_iterator I = NewOps.begin(), |
| 1931 | E = NewOps.end(); I != E; ++I) |
| 1932 | MulOpLists[M.find(*I)->second].push_back(*I); |
| 1933 | // Re-generate the operands list. |
| 1934 | Ops.clear(); |
| 1935 | if (AccumulatedConstant != 0) |
| 1936 | Ops.push_back(getConstant(AccumulatedConstant)); |
| 1937 | for (std::map<APInt, SmallVector<const SCEV *, 4>, APIntCompare>::iterator |
| 1938 | I = MulOpLists.begin(), E = MulOpLists.end(); I != E; ++I) |
| 1939 | if (I->first != 0) |
| 1940 | Ops.push_back(getMulExpr(getConstant(I->first), |
| 1941 | getAddExpr(I->second))); |
| 1942 | if (Ops.empty()) |
| 1943 | return getConstant(Ty, 0); |
| 1944 | if (Ops.size() == 1) |
| 1945 | return Ops[0]; |
| 1946 | return getAddExpr(Ops); |
| 1947 | } |
| 1948 | } |
| 1949 | |
| 1950 | // If we are adding something to a multiply expression, make sure the |
| 1951 | // something is not already an operand of the multiply. If so, merge it into |
| 1952 | // the multiply. |
| 1953 | for (; Idx < Ops.size() && isa<SCEVMulExpr>(Ops[Idx]); ++Idx) { |
| 1954 | const SCEVMulExpr *Mul = cast<SCEVMulExpr>(Ops[Idx]); |
| 1955 | for (unsigned MulOp = 0, e = Mul->getNumOperands(); MulOp != e; ++MulOp) { |
| 1956 | const SCEV *MulOpSCEV = Mul->getOperand(MulOp); |
| 1957 | if (isa<SCEVConstant>(MulOpSCEV)) |
| 1958 | continue; |
| 1959 | for (unsigned AddOp = 0, e = Ops.size(); AddOp != e; ++AddOp) |
| 1960 | if (MulOpSCEV == Ops[AddOp]) { |
| 1961 | // Fold W + X + (X * Y * Z) --> W + (X * ((Y*Z)+1)) |
| 1962 | const SCEV *InnerMul = Mul->getOperand(MulOp == 0); |
| 1963 | if (Mul->getNumOperands() != 2) { |
| 1964 | // If the multiply has more than two operands, we must get the |
| 1965 | // Y*Z term. |
| 1966 | SmallVector<const SCEV *, 4> MulOps(Mul->op_begin(), |
| 1967 | Mul->op_begin()+MulOp); |
| 1968 | MulOps.append(Mul->op_begin()+MulOp+1, Mul->op_end()); |
| 1969 | InnerMul = getMulExpr(MulOps); |
| 1970 | } |
| 1971 | const SCEV *One = getConstant(Ty, 1); |
| 1972 | const SCEV *AddOne = getAddExpr(One, InnerMul); |
| 1973 | const SCEV *OuterMul = getMulExpr(AddOne, MulOpSCEV); |
| 1974 | if (Ops.size() == 2) return OuterMul; |
| 1975 | if (AddOp < Idx) { |
| 1976 | Ops.erase(Ops.begin()+AddOp); |
| 1977 | Ops.erase(Ops.begin()+Idx-1); |
| 1978 | } else { |
| 1979 | Ops.erase(Ops.begin()+Idx); |
| 1980 | Ops.erase(Ops.begin()+AddOp-1); |
| 1981 | } |
| 1982 | Ops.push_back(OuterMul); |
| 1983 | return getAddExpr(Ops); |
| 1984 | } |
| 1985 | |
| 1986 | // Check this multiply against other multiplies being added together. |
| 1987 | for (unsigned OtherMulIdx = Idx+1; |
| 1988 | OtherMulIdx < Ops.size() && isa<SCEVMulExpr>(Ops[OtherMulIdx]); |
| 1989 | ++OtherMulIdx) { |
| 1990 | const SCEVMulExpr *OtherMul = cast<SCEVMulExpr>(Ops[OtherMulIdx]); |
| 1991 | // If MulOp occurs in OtherMul, we can fold the two multiplies |
| 1992 | // together. |
| 1993 | for (unsigned OMulOp = 0, e = OtherMul->getNumOperands(); |
| 1994 | OMulOp != e; ++OMulOp) |
| 1995 | if (OtherMul->getOperand(OMulOp) == MulOpSCEV) { |
| 1996 | // Fold X + (A*B*C) + (A*D*E) --> X + (A*(B*C+D*E)) |
| 1997 | const SCEV *InnerMul1 = Mul->getOperand(MulOp == 0); |
| 1998 | if (Mul->getNumOperands() != 2) { |
| 1999 | SmallVector<const SCEV *, 4> MulOps(Mul->op_begin(), |
| 2000 | Mul->op_begin()+MulOp); |
| 2001 | MulOps.append(Mul->op_begin()+MulOp+1, Mul->op_end()); |
| 2002 | InnerMul1 = getMulExpr(MulOps); |
| 2003 | } |
| 2004 | const SCEV *InnerMul2 = OtherMul->getOperand(OMulOp == 0); |
| 2005 | if (OtherMul->getNumOperands() != 2) { |
| 2006 | SmallVector<const SCEV *, 4> MulOps(OtherMul->op_begin(), |
| 2007 | OtherMul->op_begin()+OMulOp); |
| 2008 | MulOps.append(OtherMul->op_begin()+OMulOp+1, OtherMul->op_end()); |
| 2009 | InnerMul2 = getMulExpr(MulOps); |
| 2010 | } |
| 2011 | const SCEV *InnerMulSum = getAddExpr(InnerMul1,InnerMul2); |
| 2012 | const SCEV *OuterMul = getMulExpr(MulOpSCEV, InnerMulSum); |
| 2013 | if (Ops.size() == 2) return OuterMul; |
| 2014 | Ops.erase(Ops.begin()+Idx); |
| 2015 | Ops.erase(Ops.begin()+OtherMulIdx-1); |
| 2016 | Ops.push_back(OuterMul); |
| 2017 | return getAddExpr(Ops); |
| 2018 | } |
| 2019 | } |
| 2020 | } |
| 2021 | } |
| 2022 | |
| 2023 | // If there are any add recurrences in the operands list, see if any other |
| 2024 | // added values are loop invariant. If so, we can fold them into the |
| 2025 | // recurrence. |
| 2026 | while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddRecExpr) |
| 2027 | ++Idx; |
| 2028 | |
| 2029 | // Scan over all recurrences, trying to fold loop invariants into them. |
| 2030 | for (; Idx < Ops.size() && isa<SCEVAddRecExpr>(Ops[Idx]); ++Idx) { |
| 2031 | // Scan all of the other operands to this add and add them to the vector if |
| 2032 | // they are loop invariant w.r.t. the recurrence. |
| 2033 | SmallVector<const SCEV *, 8> LIOps; |
| 2034 | const SCEVAddRecExpr *AddRec = cast<SCEVAddRecExpr>(Ops[Idx]); |
| 2035 | const Loop *AddRecLoop = AddRec->getLoop(); |
| 2036 | for (unsigned i = 0, e = Ops.size(); i != e; ++i) |
| 2037 | if (isLoopInvariant(Ops[i], AddRecLoop)) { |
| 2038 | LIOps.push_back(Ops[i]); |
| 2039 | Ops.erase(Ops.begin()+i); |
| 2040 | --i; --e; |
| 2041 | } |
| 2042 | |
| 2043 | // If we found some loop invariants, fold them into the recurrence. |
| 2044 | if (!LIOps.empty()) { |
| 2045 | // NLI + LI + {Start,+,Step} --> NLI + {LI+Start,+,Step} |
| 2046 | LIOps.push_back(AddRec->getStart()); |
| 2047 | |
| 2048 | SmallVector<const SCEV *, 4> AddRecOps(AddRec->op_begin(), |
| 2049 | AddRec->op_end()); |
| 2050 | AddRecOps[0] = getAddExpr(LIOps); |
| 2051 | |
| 2052 | // Build the new addrec. Propagate the NUW and NSW flags if both the |
| 2053 | // outer add and the inner addrec are guaranteed to have no overflow. |
| 2054 | // Always propagate NW. |
| 2055 | Flags = AddRec->getNoWrapFlags(setFlags(Flags, SCEV::FlagNW)); |
| 2056 | const SCEV *NewRec = getAddRecExpr(AddRecOps, AddRecLoop, Flags); |
| 2057 | |
| 2058 | // If all of the other operands were loop invariant, we are done. |
| 2059 | if (Ops.size() == 1) return NewRec; |
| 2060 | |
| 2061 | // Otherwise, add the folded AddRec by the non-invariant parts. |
| 2062 | for (unsigned i = 0;; ++i) |
| 2063 | if (Ops[i] == AddRec) { |
| 2064 | Ops[i] = NewRec; |
| 2065 | break; |
| 2066 | } |
| 2067 | return getAddExpr(Ops); |
| 2068 | } |
| 2069 | |
| 2070 | // Okay, if there weren't any loop invariants to be folded, check to see if |
| 2071 | // there are multiple AddRec's with the same loop induction variable being |
| 2072 | // added together. If so, we can fold them. |
| 2073 | for (unsigned OtherIdx = Idx+1; |
| 2074 | OtherIdx < Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]); |
| 2075 | ++OtherIdx) |
| 2076 | if (AddRecLoop == cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()) { |
| 2077 | // Other + {A,+,B}<L> + {C,+,D}<L> --> Other + {A+C,+,B+D}<L> |
| 2078 | SmallVector<const SCEV *, 4> AddRecOps(AddRec->op_begin(), |
| 2079 | AddRec->op_end()); |
| 2080 | for (; OtherIdx != Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]); |
| 2081 | ++OtherIdx) |
| 2082 | if (const SCEVAddRecExpr *OtherAddRec = |
| 2083 | dyn_cast<SCEVAddRecExpr>(Ops[OtherIdx])) |
| 2084 | if (OtherAddRec->getLoop() == AddRecLoop) { |
| 2085 | for (unsigned i = 0, e = OtherAddRec->getNumOperands(); |
| 2086 | i != e; ++i) { |
| 2087 | if (i >= AddRecOps.size()) { |
| 2088 | AddRecOps.append(OtherAddRec->op_begin()+i, |
| 2089 | OtherAddRec->op_end()); |
| 2090 | break; |
| 2091 | } |
| 2092 | AddRecOps[i] = getAddExpr(AddRecOps[i], |
| 2093 | OtherAddRec->getOperand(i)); |
| 2094 | } |
| 2095 | Ops.erase(Ops.begin() + OtherIdx); --OtherIdx; |
| 2096 | } |
| 2097 | // Step size has changed, so we cannot guarantee no self-wraparound. |
| 2098 | Ops[Idx] = getAddRecExpr(AddRecOps, AddRecLoop, SCEV::FlagAnyWrap); |
| 2099 | return getAddExpr(Ops); |
| 2100 | } |
| 2101 | |
| 2102 | // Otherwise couldn't fold anything into this recurrence. Move onto the |
| 2103 | // next one. |
| 2104 | } |
| 2105 | |
| 2106 | // Okay, it looks like we really DO need an add expr. Check to see if we |
| 2107 | // already have one, otherwise create a new one. |
| 2108 | FoldingSetNodeID ID; |
| 2109 | ID.AddInteger(scAddExpr); |
| 2110 | for (unsigned i = 0, e = Ops.size(); i != e; ++i) |
| 2111 | ID.AddPointer(Ops[i]); |
| 2112 | void *IP = nullptr; |
| 2113 | SCEVAddExpr *S = |
| 2114 | static_cast<SCEVAddExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP)); |
| 2115 | if (!S) { |
| 2116 | const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size()); |
| 2117 | std::uninitialized_copy(Ops.begin(), Ops.end(), O); |
| 2118 | S = new (SCEVAllocator) SCEVAddExpr(ID.Intern(SCEVAllocator), |
| 2119 | O, Ops.size()); |
| 2120 | UniqueSCEVs.InsertNode(S, IP); |
| 2121 | } |
| 2122 | S->setNoWrapFlags(Flags); |
| 2123 | return S; |
| 2124 | } |
| 2125 | |
| 2126 | static uint64_t umul_ov(uint64_t i, uint64_t j, bool &Overflow) { |
| 2127 | uint64_t k = i*j; |
| 2128 | if (j > 1 && k / j != i) Overflow = true; |
| 2129 | return k; |
| 2130 | } |
| 2131 | |
| 2132 | /// Compute the result of "n choose k", the binomial coefficient. If an |
| 2133 | /// intermediate computation overflows, Overflow will be set and the return will |
| 2134 | /// be garbage. Overflow is not cleared on absence of overflow. |
| 2135 | static uint64_t Choose(uint64_t n, uint64_t k, bool &Overflow) { |
| 2136 | // We use the multiplicative formula: |
| 2137 | // n(n-1)(n-2)...(n-(k-1)) / k(k-1)(k-2)...1 . |
| 2138 | // At each iteration, we take the n-th term of the numeral and divide by the |
| 2139 | // (k-n)th term of the denominator. This division will always produce an |
| 2140 | // integral result, and helps reduce the chance of overflow in the |
| 2141 | // intermediate computations. However, we can still overflow even when the |
| 2142 | // final result would fit. |
| 2143 | |
| 2144 | if (n == 0 || n == k) return 1; |
| 2145 | if (k > n) return 0; |
| 2146 | |
| 2147 | if (k > n/2) |
| 2148 | k = n-k; |
| 2149 | |
| 2150 | uint64_t r = 1; |
| 2151 | for (uint64_t i = 1; i <= k; ++i) { |
| 2152 | r = umul_ov(r, n-(i-1), Overflow); |
| 2153 | r /= i; |
| 2154 | } |
| 2155 | return r; |
| 2156 | } |
| 2157 | |
| 2158 | /// getMulExpr - Get a canonical multiply expression, or something simpler if |
| 2159 | /// possible. |
| 2160 | const SCEV *ScalarEvolution::getMulExpr(SmallVectorImpl<const SCEV *> &Ops, |
| 2161 | SCEV::NoWrapFlags Flags) { |
| 2162 | assert(Flags == maskFlags(Flags, SCEV::FlagNUW | SCEV::FlagNSW) &&((Flags == maskFlags(Flags, SCEV::FlagNUW | SCEV::FlagNSW) && "only nuw or nsw allowed") ? static_cast<void> (0) : __assert_fail ("Flags == maskFlags(Flags, SCEV::FlagNUW | SCEV::FlagNSW) && \"only nuw or nsw allowed\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 2163, __PRETTY_FUNCTION__)) |
| 2163 | "only nuw or nsw allowed")((Flags == maskFlags(Flags, SCEV::FlagNUW | SCEV::FlagNSW) && "only nuw or nsw allowed") ? static_cast<void> (0) : __assert_fail ("Flags == maskFlags(Flags, SCEV::FlagNUW | SCEV::FlagNSW) && \"only nuw or nsw allowed\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 2163, __PRETTY_FUNCTION__)); |
| 2164 | assert(!Ops.empty() && "Cannot get empty mul!")((!Ops.empty() && "Cannot get empty mul!") ? static_cast <void> (0) : __assert_fail ("!Ops.empty() && \"Cannot get empty mul!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 2164, __PRETTY_FUNCTION__)); |
| 2165 | if (Ops.size() == 1) return Ops[0]; |
| 2166 | #ifndef NDEBUG |
| 2167 | Type *ETy = getEffectiveSCEVType(Ops[0]->getType()); |
| 2168 | for (unsigned i = 1, e = Ops.size(); i != e; ++i) |
| 2169 | assert(getEffectiveSCEVType(Ops[i]->getType()) == ETy &&((getEffectiveSCEVType(Ops[i]->getType()) == ETy && "SCEVMulExpr operand types don't match!") ? static_cast<void > (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVMulExpr operand types don't match!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 2170, __PRETTY_FUNCTION__)) |
| 2170 | "SCEVMulExpr operand types don't match!")((getEffectiveSCEVType(Ops[i]->getType()) == ETy && "SCEVMulExpr operand types don't match!") ? static_cast<void > (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVMulExpr operand types don't match!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 2170, __PRETTY_FUNCTION__)); |
| 2171 | #endif |
| 2172 | |
| 2173 | // If FlagNSW is true and all the operands are non-negative, infer FlagNUW. |
| 2174 | // And vice-versa. |
| 2175 | int SignOrUnsignMask = SCEV::FlagNUW | SCEV::FlagNSW; |
| 2176 | SCEV::NoWrapFlags SignOrUnsignWrap = maskFlags(Flags, SignOrUnsignMask); |
| 2177 | if (SignOrUnsignWrap && (SignOrUnsignWrap != SignOrUnsignMask)) { |
| 2178 | bool All = true; |
| 2179 | for (SmallVectorImpl<const SCEV *>::const_iterator I = Ops.begin(), |
| 2180 | E = Ops.end(); I != E; ++I) |
| 2181 | if (!isKnownNonNegative(*I)) { |
| 2182 | All = false; |
| 2183 | break; |
| 2184 | } |
| 2185 | if (All) Flags = setFlags(Flags, (SCEV::NoWrapFlags)SignOrUnsignMask); |
| 2186 | } |
| 2187 | |
| 2188 | // Sort by complexity, this groups all similar expression types together. |
| 2189 | GroupByComplexity(Ops, LI); |
| 2190 | |
| 2191 | // If there are any constants, fold them together. |
| 2192 | unsigned Idx = 0; |
| 2193 | if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) { |
| 2194 | |
| 2195 | // C1*(C2+V) -> C1*C2 + C1*V |
| 2196 | if (Ops.size() == 2) |
| 2197 | if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[1])) |
| 2198 | if (Add->getNumOperands() == 2 && |
| 2199 | isa<SCEVConstant>(Add->getOperand(0))) |
| 2200 | return getAddExpr(getMulExpr(LHSC, Add->getOperand(0)), |
| 2201 | getMulExpr(LHSC, Add->getOperand(1))); |
| 2202 | |
| 2203 | ++Idx; |
| 2204 | while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) { |
| 2205 | // We found two constants, fold them together! |
| 2206 | ConstantInt *Fold = ConstantInt::get(getContext(), |
| 2207 | LHSC->getValue()->getValue() * |
| 2208 | RHSC->getValue()->getValue()); |
| 2209 | Ops[0] = getConstant(Fold); |
| 2210 | Ops.erase(Ops.begin()+1); // Erase the folded element |
| 2211 | if (Ops.size() == 1) return Ops[0]; |
| 2212 | LHSC = cast<SCEVConstant>(Ops[0]); |
| 2213 | } |
| 2214 | |
| 2215 | // If we are left with a constant one being multiplied, strip it off. |
| 2216 | if (cast<SCEVConstant>(Ops[0])->getValue()->equalsInt(1)) { |
| 2217 | Ops.erase(Ops.begin()); |
| 2218 | --Idx; |
| 2219 | } else if (cast<SCEVConstant>(Ops[0])->getValue()->isZero()) { |
| 2220 | // If we have a multiply of zero, it will always be zero. |
| 2221 | return Ops[0]; |
| 2222 | } else if (Ops[0]->isAllOnesValue()) { |
| 2223 | // If we have a mul by -1 of an add, try distributing the -1 among the |
| 2224 | // add operands. |
| 2225 | if (Ops.size() == 2) { |
| 2226 | if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[1])) { |
| 2227 | SmallVector<const SCEV *, 4> NewOps; |
| 2228 | bool AnyFolded = false; |
| 2229 | for (SCEVAddRecExpr::op_iterator I = Add->op_begin(), |
| 2230 | E = Add->op_end(); I != E; ++I) { |
| 2231 | const SCEV *Mul = getMulExpr(Ops[0], *I); |
| 2232 | if (!isa<SCEVMulExpr>(Mul)) AnyFolded = true; |
| 2233 | NewOps.push_back(Mul); |
| 2234 | } |
| 2235 | if (AnyFolded) |
| 2236 | return getAddExpr(NewOps); |
| 2237 | } |
| 2238 | else if (const SCEVAddRecExpr * |
| 2239 | AddRec = dyn_cast<SCEVAddRecExpr>(Ops[1])) { |
| 2240 | // Negation preserves a recurrence's no self-wrap property. |
| 2241 | SmallVector<const SCEV *, 4> Operands; |
| 2242 | for (SCEVAddRecExpr::op_iterator I = AddRec->op_begin(), |
| 2243 | E = AddRec->op_end(); I != E; ++I) { |
| 2244 | Operands.push_back(getMulExpr(Ops[0], *I)); |
| 2245 | } |
| 2246 | return getAddRecExpr(Operands, AddRec->getLoop(), |
| 2247 | AddRec->getNoWrapFlags(SCEV::FlagNW)); |
| 2248 | } |
| 2249 | } |
| 2250 | } |
| 2251 | |
| 2252 | if (Ops.size() == 1) |
| 2253 | return Ops[0]; |
| 2254 | } |
| 2255 | |
| 2256 | // Skip over the add expression until we get to a multiply. |
| 2257 | while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scMulExpr) |
| 2258 | ++Idx; |
| 2259 | |
| 2260 | // If there are mul operands inline them all into this expression. |
| 2261 | if (Idx < Ops.size()) { |
| 2262 | bool DeletedMul = false; |
| 2263 | while (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(Ops[Idx])) { |
| 2264 | // If we have an mul, expand the mul operands onto the end of the operands |
| 2265 | // list. |
| 2266 | Ops.erase(Ops.begin()+Idx); |
| 2267 | Ops.append(Mul->op_begin(), Mul->op_end()); |
| 2268 | DeletedMul = true; |
| 2269 | } |
| 2270 | |
| 2271 | // If we deleted at least one mul, we added operands to the end of the list, |
| 2272 | // and they are not necessarily sorted. Recurse to resort and resimplify |
| 2273 | // any operands we just acquired. |
| 2274 | if (DeletedMul) |
| 2275 | return getMulExpr(Ops); |
| 2276 | } |
| 2277 | |
| 2278 | // If there are any add recurrences in the operands list, see if any other |
| 2279 | // added values are loop invariant. If so, we can fold them into the |
| 2280 | // recurrence. |
| 2281 | while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddRecExpr) |
| 2282 | ++Idx; |
| 2283 | |
| 2284 | // Scan over all recurrences, trying to fold loop invariants into them. |
| 2285 | for (; Idx < Ops.size() && isa<SCEVAddRecExpr>(Ops[Idx]); ++Idx) { |
| 2286 | // Scan all of the other operands to this mul and add them to the vector if |
| 2287 | // they are loop invariant w.r.t. the recurrence. |
| 2288 | SmallVector<const SCEV *, 8> LIOps; |
| 2289 | const SCEVAddRecExpr *AddRec = cast<SCEVAddRecExpr>(Ops[Idx]); |
| 2290 | const Loop *AddRecLoop = AddRec->getLoop(); |
| 2291 | for (unsigned i = 0, e = Ops.size(); i != e; ++i) |
| 2292 | if (isLoopInvariant(Ops[i], AddRecLoop)) { |
| 2293 | LIOps.push_back(Ops[i]); |
| 2294 | Ops.erase(Ops.begin()+i); |
| 2295 | --i; --e; |
| 2296 | } |
| 2297 | |
| 2298 | // If we found some loop invariants, fold them into the recurrence. |
| 2299 | if (!LIOps.empty()) { |
| 2300 | // NLI * LI * {Start,+,Step} --> NLI * {LI*Start,+,LI*Step} |
| 2301 | SmallVector<const SCEV *, 4> NewOps; |
| 2302 | NewOps.reserve(AddRec->getNumOperands()); |
| 2303 | const SCEV *Scale = getMulExpr(LIOps); |
| 2304 | for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i) |
| 2305 | NewOps.push_back(getMulExpr(Scale, AddRec->getOperand(i))); |
| 2306 | |
| 2307 | // Build the new addrec. Propagate the NUW and NSW flags if both the |
| 2308 | // outer mul and the inner addrec are guaranteed to have no overflow. |
| 2309 | // |
| 2310 | // No self-wrap cannot be guaranteed after changing the step size, but |
| 2311 | // will be inferred if either NUW or NSW is true. |
| 2312 | Flags = AddRec->getNoWrapFlags(clearFlags(Flags, SCEV::FlagNW)); |
| 2313 | const SCEV *NewRec = getAddRecExpr(NewOps, AddRecLoop, Flags); |
| 2314 | |
| 2315 | // If all of the other operands were loop invariant, we are done. |
| 2316 | if (Ops.size() == 1) return NewRec; |
| 2317 | |
| 2318 | // Otherwise, multiply the folded AddRec by the non-invariant parts. |
| 2319 | for (unsigned i = 0;; ++i) |
| 2320 | if (Ops[i] == AddRec) { |
| 2321 | Ops[i] = NewRec; |
| 2322 | break; |
| 2323 | } |
| 2324 | return getMulExpr(Ops); |
| 2325 | } |
| 2326 | |
| 2327 | // Okay, if there weren't any loop invariants to be folded, check to see if |
| 2328 | // there are multiple AddRec's with the same loop induction variable being |
| 2329 | // multiplied together. If so, we can fold them. |
| 2330 | |
| 2331 | // {A1,+,A2,+,...,+,An}<L> * {B1,+,B2,+,...,+,Bn}<L> |
| 2332 | // = {x=1 in [ sum y=x..2x [ sum z=max(y-x, y-n)..min(x,n) [ |
| 2333 | // choose(x, 2x)*choose(2x-y, x-z)*A_{y-z}*B_z |
| 2334 | // ]]],+,...up to x=2n}. |
| 2335 | // Note that the arguments to choose() are always integers with values |
| 2336 | // known at compile time, never SCEV objects. |
| 2337 | // |
| 2338 | // The implementation avoids pointless extra computations when the two |
| 2339 | // addrec's are of different length (mathematically, it's equivalent to |
| 2340 | // an infinite stream of zeros on the right). |
| 2341 | bool OpsModified = false; |
| 2342 | for (unsigned OtherIdx = Idx+1; |
| 2343 | OtherIdx != Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]); |
| 2344 | ++OtherIdx) { |
| 2345 | const SCEVAddRecExpr *OtherAddRec = |
| 2346 | dyn_cast<SCEVAddRecExpr>(Ops[OtherIdx]); |
| 2347 | if (!OtherAddRec || OtherAddRec->getLoop() != AddRecLoop) |
| 2348 | continue; |
| 2349 | |
| 2350 | bool Overflow = false; |
| 2351 | Type *Ty = AddRec->getType(); |
| 2352 | bool LargerThan64Bits = getTypeSizeInBits(Ty) > 64; |
| 2353 | SmallVector<const SCEV*, 7> AddRecOps; |
| 2354 | for (int x = 0, xe = AddRec->getNumOperands() + |
| 2355 | OtherAddRec->getNumOperands() - 1; x != xe && !Overflow; ++x) { |
| 2356 | const SCEV *Term = getConstant(Ty, 0); |
| 2357 | for (int y = x, ye = 2*x+1; y != ye && !Overflow; ++y) { |
| 2358 | uint64_t Coeff1 = Choose(x, 2*x - y, Overflow); |
| 2359 | for (int z = std::max(y-x, y-(int)AddRec->getNumOperands()+1), |
| 2360 | ze = std::min(x+1, (int)OtherAddRec->getNumOperands()); |
| 2361 | z < ze && !Overflow; ++z) { |
| 2362 | uint64_t Coeff2 = Choose(2*x - y, x-z, Overflow); |
| 2363 | uint64_t Coeff; |
| 2364 | if (LargerThan64Bits) |
| 2365 | Coeff = umul_ov(Coeff1, Coeff2, Overflow); |
| 2366 | else |
| 2367 | Coeff = Coeff1*Coeff2; |
| 2368 | const SCEV *CoeffTerm = getConstant(Ty, Coeff); |
| 2369 | const SCEV *Term1 = AddRec->getOperand(y-z); |
| 2370 | const SCEV *Term2 = OtherAddRec->getOperand(z); |
| 2371 | Term = getAddExpr(Term, getMulExpr(CoeffTerm, Term1,Term2)); |
| 2372 | } |
| 2373 | } |
| 2374 | AddRecOps.push_back(Term); |
| 2375 | } |
| 2376 | if (!Overflow) { |
| 2377 | const SCEV *NewAddRec = getAddRecExpr(AddRecOps, AddRec->getLoop(), |
| 2378 | SCEV::FlagAnyWrap); |
| 2379 | if (Ops.size() == 2) return NewAddRec; |
| 2380 | Ops[Idx] = NewAddRec; |
| 2381 | Ops.erase(Ops.begin() + OtherIdx); --OtherIdx; |
| 2382 | OpsModified = true; |
| 2383 | AddRec = dyn_cast<SCEVAddRecExpr>(NewAddRec); |
| 2384 | if (!AddRec) |
| 2385 | break; |
| 2386 | } |
| 2387 | } |
| 2388 | if (OpsModified) |
| 2389 | return getMulExpr(Ops); |
| 2390 | |
| 2391 | // Otherwise couldn't fold anything into this recurrence. Move onto the |
| 2392 | // next one. |
| 2393 | } |
| 2394 | |
| 2395 | // Okay, it looks like we really DO need an mul expr. Check to see if we |
| 2396 | // already have one, otherwise create a new one. |
| 2397 | FoldingSetNodeID ID; |
| 2398 | ID.AddInteger(scMulExpr); |
| 2399 | for (unsigned i = 0, e = Ops.size(); i != e; ++i) |
| 2400 | ID.AddPointer(Ops[i]); |
| 2401 | void *IP = nullptr; |
| 2402 | SCEVMulExpr *S = |
| 2403 | static_cast<SCEVMulExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP)); |
| 2404 | if (!S) { |
| 2405 | const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size()); |
| 2406 | std::uninitialized_copy(Ops.begin(), Ops.end(), O); |
| 2407 | S = new (SCEVAllocator) SCEVMulExpr(ID.Intern(SCEVAllocator), |
| 2408 | O, Ops.size()); |
| 2409 | UniqueSCEVs.InsertNode(S, IP); |
| 2410 | } |
| 2411 | S->setNoWrapFlags(Flags); |
| 2412 | return S; |
| 2413 | } |
| 2414 | |
| 2415 | /// getUDivExpr - Get a canonical unsigned division expression, or something |
| 2416 | /// simpler if possible. |
| 2417 | const SCEV *ScalarEvolution::getUDivExpr(const SCEV *LHS, |
| 2418 | const SCEV *RHS) { |
| 2419 | assert(getEffectiveSCEVType(LHS->getType()) ==((getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType (RHS->getType()) && "SCEVUDivExpr operand types don't match!" ) ? static_cast<void> (0) : __assert_fail ("getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType(RHS->getType()) && \"SCEVUDivExpr operand types don't match!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 2421, __PRETTY_FUNCTION__)) |
| 2420 | getEffectiveSCEVType(RHS->getType()) &&((getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType (RHS->getType()) && "SCEVUDivExpr operand types don't match!" ) ? static_cast<void> (0) : __assert_fail ("getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType(RHS->getType()) && \"SCEVUDivExpr operand types don't match!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 2421, __PRETTY_FUNCTION__)) |
| 2421 | "SCEVUDivExpr operand types don't match!")((getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType (RHS->getType()) && "SCEVUDivExpr operand types don't match!" ) ? static_cast<void> (0) : __assert_fail ("getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType(RHS->getType()) && \"SCEVUDivExpr operand types don't match!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 2421, __PRETTY_FUNCTION__)); |
| 2422 | |
| 2423 | if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS)) { |
| 2424 | if (RHSC->getValue()->equalsInt(1)) |
| 2425 | return LHS; // X udiv 1 --> x |
| 2426 | // If the denominator is zero, the result of the udiv is undefined. Don't |
| 2427 | // try to analyze it, because the resolution chosen here may differ from |
| 2428 | // the resolution chosen in other parts of the compiler. |
| 2429 | if (!RHSC->getValue()->isZero()) { |
| 2430 | // Determine if the division can be folded into the operands of |
| 2431 | // its operands. |
| 2432 | // TODO: Generalize this to non-constants by using known-bits information. |
| 2433 | Type *Ty = LHS->getType(); |
| 2434 | unsigned LZ = RHSC->getValue()->getValue().countLeadingZeros(); |
| 2435 | unsigned MaxShiftAmt = getTypeSizeInBits(Ty) - LZ - 1; |
| 2436 | // For non-power-of-two values, effectively round the value up to the |
| 2437 | // nearest power of two. |
| 2438 | if (!RHSC->getValue()->getValue().isPowerOf2()) |
| 2439 | ++MaxShiftAmt; |
| 2440 | IntegerType *ExtTy = |
| 2441 | IntegerType::get(getContext(), getTypeSizeInBits(Ty) + MaxShiftAmt); |
| 2442 | if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(LHS)) |
| 2443 | if (const SCEVConstant *Step = |
| 2444 | dyn_cast<SCEVConstant>(AR->getStepRecurrence(*this))) { |
| 2445 | // {X,+,N}/C --> {X/C,+,N/C} if safe and N/C can be folded. |
| 2446 | const APInt &StepInt = Step->getValue()->getValue(); |
| 2447 | const APInt &DivInt = RHSC->getValue()->getValue(); |
| 2448 | if (!StepInt.urem(DivInt) && |
| 2449 | getZeroExtendExpr(AR, ExtTy) == |
| 2450 | getAddRecExpr(getZeroExtendExpr(AR->getStart(), ExtTy), |
| 2451 | getZeroExtendExpr(Step, ExtTy), |
| 2452 | AR->getLoop(), SCEV::FlagAnyWrap)) { |
| 2453 | SmallVector<const SCEV *, 4> Operands; |
| 2454 | for (unsigned i = 0, e = AR->getNumOperands(); i != e; ++i) |
| 2455 | Operands.push_back(getUDivExpr(AR->getOperand(i), RHS)); |
| 2456 | return getAddRecExpr(Operands, AR->getLoop(), |
| 2457 | SCEV::FlagNW); |
| 2458 | } |
| 2459 | /// Get a canonical UDivExpr for a recurrence. |
| 2460 | /// {X,+,N}/C => {Y,+,N}/C where Y=X-(X%N). Safe when C%N=0. |
| 2461 | // We can currently only fold X%N if X is constant. |
| 2462 | const SCEVConstant *StartC = dyn_cast<SCEVConstant>(AR->getStart()); |
| 2463 | if (StartC && !DivInt.urem(StepInt) && |
| 2464 | getZeroExtendExpr(AR, ExtTy) == |
| 2465 | getAddRecExpr(getZeroExtendExpr(AR->getStart(), ExtTy), |
| 2466 | getZeroExtendExpr(Step, ExtTy), |
| 2467 | AR->getLoop(), SCEV::FlagAnyWrap)) { |
| 2468 | const APInt &StartInt = StartC->getValue()->getValue(); |
| 2469 | const APInt &StartRem = StartInt.urem(StepInt); |
| 2470 | if (StartRem != 0) |
| 2471 | LHS = getAddRecExpr(getConstant(StartInt - StartRem), Step, |
| 2472 | AR->getLoop(), SCEV::FlagNW); |
| 2473 | } |
| 2474 | } |
| 2475 | // (A*B)/C --> A*(B/C) if safe and B/C can be folded. |
| 2476 | if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(LHS)) { |
| 2477 | SmallVector<const SCEV *, 4> Operands; |
| 2478 | for (unsigned i = 0, e = M->getNumOperands(); i != e; ++i) |
| 2479 | Operands.push_back(getZeroExtendExpr(M->getOperand(i), ExtTy)); |
| 2480 | if (getZeroExtendExpr(M, ExtTy) == getMulExpr(Operands)) |
| 2481 | // Find an operand that's safely divisible. |
| 2482 | for (unsigned i = 0, e = M->getNumOperands(); i != e; ++i) { |
| 2483 | const SCEV *Op = M->getOperand(i); |
| 2484 | const SCEV *Div = getUDivExpr(Op, RHSC); |
| 2485 | if (!isa<SCEVUDivExpr>(Div) && getMulExpr(Div, RHSC) == Op) { |
| 2486 | Operands = SmallVector<const SCEV *, 4>(M->op_begin(), |
| 2487 | M->op_end()); |
| 2488 | Operands[i] = Div; |
| 2489 | return getMulExpr(Operands); |
| 2490 | } |
| 2491 | } |
| 2492 | } |
| 2493 | // (A+B)/C --> (A/C + B/C) if safe and A/C and B/C can be folded. |
| 2494 | if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(LHS)) { |
| 2495 | SmallVector<const SCEV *, 4> Operands; |
| 2496 | for (unsigned i = 0, e = A->getNumOperands(); i != e; ++i) |
| 2497 | Operands.push_back(getZeroExtendExpr(A->getOperand(i), ExtTy)); |
| 2498 | if (getZeroExtendExpr(A, ExtTy) == getAddExpr(Operands)) { |
| 2499 | Operands.clear(); |
| 2500 | for (unsigned i = 0, e = A->getNumOperands(); i != e; ++i) { |
| 2501 | const SCEV *Op = getUDivExpr(A->getOperand(i), RHS); |
| 2502 | if (isa<SCEVUDivExpr>(Op) || |
| 2503 | getMulExpr(Op, RHS) != A->getOperand(i)) |
| 2504 | break; |
| 2505 | Operands.push_back(Op); |
| 2506 | } |
| 2507 | if (Operands.size() == A->getNumOperands()) |
| 2508 | return getAddExpr(Operands); |
| 2509 | } |
| 2510 | } |
| 2511 | |
| 2512 | // Fold if both operands are constant. |
| 2513 | if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(LHS)) { |
| 2514 | Constant *LHSCV = LHSC->getValue(); |
| 2515 | Constant *RHSCV = RHSC->getValue(); |
| 2516 | return getConstant(cast<ConstantInt>(ConstantExpr::getUDiv(LHSCV, |
| 2517 | RHSCV))); |
| 2518 | } |
| 2519 | } |
| 2520 | } |
| 2521 | |
| 2522 | FoldingSetNodeID ID; |
| 2523 | ID.AddInteger(scUDivExpr); |
| 2524 | ID.AddPointer(LHS); |
| 2525 | ID.AddPointer(RHS); |
| 2526 | void *IP = nullptr; |
| 2527 | if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S; |
| 2528 | SCEV *S = new (SCEVAllocator) SCEVUDivExpr(ID.Intern(SCEVAllocator), |
| 2529 | LHS, RHS); |
| 2530 | UniqueSCEVs.InsertNode(S, IP); |
| 2531 | return S; |
| 2532 | } |
| 2533 | |
| 2534 | static const APInt gcd(const SCEVConstant *C1, const SCEVConstant *C2) { |
| 2535 | APInt A = C1->getValue()->getValue().abs(); |
| 2536 | APInt B = C2->getValue()->getValue().abs(); |
| 2537 | uint32_t ABW = A.getBitWidth(); |
| 2538 | uint32_t BBW = B.getBitWidth(); |
| 2539 | |
| 2540 | if (ABW > BBW) |
| 2541 | B = B.zext(ABW); |
| 2542 | else if (ABW < BBW) |
| 2543 | A = A.zext(BBW); |
| 2544 | |
| 2545 | return APIntOps::GreatestCommonDivisor(A, B); |
| 2546 | } |
| 2547 | |
| 2548 | /// getUDivExactExpr - Get a canonical unsigned division expression, or |
| 2549 | /// something simpler if possible. There is no representation for an exact udiv |
| 2550 | /// in SCEV IR, but we can attempt to remove factors from the LHS and RHS. |
| 2551 | /// We can't do this when it's not exact because the udiv may be clearing bits. |
| 2552 | const SCEV *ScalarEvolution::getUDivExactExpr(const SCEV *LHS, |
| 2553 | const SCEV *RHS) { |
| 2554 | // TODO: we could try to find factors in all sorts of things, but for now we |
| 2555 | // just deal with u/exact (multiply, constant). See SCEVDivision towards the |
| 2556 | // end of this file for inspiration. |
| 2557 | |
| 2558 | const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(LHS); |
| 2559 | if (!Mul) |
| 2560 | return getUDivExpr(LHS, RHS); |
| 2561 | |
| 2562 | if (const SCEVConstant *RHSCst = dyn_cast<SCEVConstant>(RHS)) { |
| 2563 | // If the mulexpr multiplies by a constant, then that constant must be the |
| 2564 | // first element of the mulexpr. |
| 2565 | if (const SCEVConstant *LHSCst = |
| 2566 | dyn_cast<SCEVConstant>(Mul->getOperand(0))) { |
| 2567 | if (LHSCst == RHSCst) { |
| 2568 | SmallVector<const SCEV *, 2> Operands; |
| 2569 | Operands.append(Mul->op_begin() + 1, Mul->op_end()); |
| 2570 | return getMulExpr(Operands); |
| 2571 | } |
| 2572 | |
| 2573 | // We can't just assume that LHSCst divides RHSCst cleanly, it could be |
| 2574 | // that there's a factor provided by one of the other terms. We need to |
| 2575 | // check. |
| 2576 | APInt Factor = gcd(LHSCst, RHSCst); |
| 2577 | if (!Factor.isIntN(1)) { |
| 2578 | LHSCst = cast<SCEVConstant>( |
| 2579 | getConstant(LHSCst->getValue()->getValue().udiv(Factor))); |
| 2580 | RHSCst = cast<SCEVConstant>( |
| 2581 | getConstant(RHSCst->getValue()->getValue().udiv(Factor))); |
| 2582 | SmallVector<const SCEV *, 2> Operands; |
| 2583 | Operands.push_back(LHSCst); |
| 2584 | Operands.append(Mul->op_begin() + 1, Mul->op_end()); |
| 2585 | LHS = getMulExpr(Operands); |
| 2586 | RHS = RHSCst; |
| 2587 | Mul = dyn_cast<SCEVMulExpr>(LHS); |
| 2588 | if (!Mul) |
| 2589 | return getUDivExactExpr(LHS, RHS); |
| 2590 | } |
| 2591 | } |
| 2592 | } |
| 2593 | |
| 2594 | for (int i = 0, e = Mul->getNumOperands(); i != e; ++i) { |
| 2595 | if (Mul->getOperand(i) == RHS) { |
| 2596 | SmallVector<const SCEV *, 2> Operands; |
| 2597 | Operands.append(Mul->op_begin(), Mul->op_begin() + i); |
| 2598 | Operands.append(Mul->op_begin() + i + 1, Mul->op_end()); |
| 2599 | return getMulExpr(Operands); |
| 2600 | } |
| 2601 | } |
| 2602 | |
| 2603 | return getUDivExpr(LHS, RHS); |
| 2604 | } |
| 2605 | |
| 2606 | /// getAddRecExpr - Get an add recurrence expression for the specified loop. |
| 2607 | /// Simplify the expression as much as possible. |
| 2608 | const SCEV *ScalarEvolution::getAddRecExpr(const SCEV *Start, const SCEV *Step, |
| 2609 | const Loop *L, |
| 2610 | SCEV::NoWrapFlags Flags) { |
| 2611 | SmallVector<const SCEV *, 4> Operands; |
| 2612 | Operands.push_back(Start); |
| 2613 | if (const SCEVAddRecExpr *StepChrec = dyn_cast<SCEVAddRecExpr>(Step)) |
| 2614 | if (StepChrec->getLoop() == L) { |
| 2615 | Operands.append(StepChrec->op_begin(), StepChrec->op_end()); |
| 2616 | return getAddRecExpr(Operands, L, maskFlags(Flags, SCEV::FlagNW)); |
| 2617 | } |
| 2618 | |
| 2619 | Operands.push_back(Step); |
| 2620 | return getAddRecExpr(Operands, L, Flags); |
| 2621 | } |
| 2622 | |
| 2623 | /// getAddRecExpr - Get an add recurrence expression for the specified loop. |
| 2624 | /// Simplify the expression as much as possible. |
| 2625 | const SCEV * |
| 2626 | ScalarEvolution::getAddRecExpr(SmallVectorImpl<const SCEV *> &Operands, |
| 2627 | const Loop *L, SCEV::NoWrapFlags Flags) { |
| 2628 | if (Operands.size() == 1) return Operands[0]; |
| 2629 | #ifndef NDEBUG |
| 2630 | Type *ETy = getEffectiveSCEVType(Operands[0]->getType()); |
| 2631 | for (unsigned i = 1, e = Operands.size(); i != e; ++i) |
| 2632 | assert(getEffectiveSCEVType(Operands[i]->getType()) == ETy &&((getEffectiveSCEVType(Operands[i]->getType()) == ETy && "SCEVAddRecExpr operand types don't match!") ? static_cast< void> (0) : __assert_fail ("getEffectiveSCEVType(Operands[i]->getType()) == ETy && \"SCEVAddRecExpr operand types don't match!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 2633, __PRETTY_FUNCTION__)) |
| 2633 | "SCEVAddRecExpr operand types don't match!")((getEffectiveSCEVType(Operands[i]->getType()) == ETy && "SCEVAddRecExpr operand types don't match!") ? static_cast< void> (0) : __assert_fail ("getEffectiveSCEVType(Operands[i]->getType()) == ETy && \"SCEVAddRecExpr operand types don't match!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 2633, __PRETTY_FUNCTION__)); |
| 2634 | for (unsigned i = 0, e = Operands.size(); i != e; ++i) |
| 2635 | assert(isLoopInvariant(Operands[i], L) &&((isLoopInvariant(Operands[i], L) && "SCEVAddRecExpr operand is not loop-invariant!" ) ? static_cast<void> (0) : __assert_fail ("isLoopInvariant(Operands[i], L) && \"SCEVAddRecExpr operand is not loop-invariant!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 2636, __PRETTY_FUNCTION__)) |
| 2636 | "SCEVAddRecExpr operand is not loop-invariant!")((isLoopInvariant(Operands[i], L) && "SCEVAddRecExpr operand is not loop-invariant!" ) ? static_cast<void> (0) : __assert_fail ("isLoopInvariant(Operands[i], L) && \"SCEVAddRecExpr operand is not loop-invariant!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 2636, __PRETTY_FUNCTION__)); |
| 2637 | #endif |
| 2638 | |
| 2639 | if (Operands.back()->isZero()) { |
| 2640 | Operands.pop_back(); |
| 2641 | return getAddRecExpr(Operands, L, SCEV::FlagAnyWrap); // {X,+,0} --> X |
| 2642 | } |
| 2643 | |
| 2644 | // It's tempting to want to call getMaxBackedgeTakenCount count here and |
| 2645 | // use that information to infer NUW and NSW flags. However, computing a |
| 2646 | // BE count requires calling getAddRecExpr, so we may not yet have a |
| 2647 | // meaningful BE count at this point (and if we don't, we'd be stuck |
| 2648 | // with a SCEVCouldNotCompute as the cached BE count). |
| 2649 | |
| 2650 | // If FlagNSW is true and all the operands are non-negative, infer FlagNUW. |
| 2651 | // And vice-versa. |
| 2652 | int SignOrUnsignMask = SCEV::FlagNUW | SCEV::FlagNSW; |
| 2653 | SCEV::NoWrapFlags SignOrUnsignWrap = maskFlags(Flags, SignOrUnsignMask); |
| 2654 | if (SignOrUnsignWrap && (SignOrUnsignWrap != SignOrUnsignMask)) { |
| 2655 | bool All = true; |
| 2656 | for (SmallVectorImpl<const SCEV *>::const_iterator I = Operands.begin(), |
| 2657 | E = Operands.end(); I != E; ++I) |
| 2658 | if (!isKnownNonNegative(*I)) { |
| 2659 | All = false; |
| 2660 | break; |
| 2661 | } |
| 2662 | if (All) Flags = setFlags(Flags, (SCEV::NoWrapFlags)SignOrUnsignMask); |
| 2663 | } |
| 2664 | |
| 2665 | // Canonicalize nested AddRecs in by nesting them in order of loop depth. |
| 2666 | if (const SCEVAddRecExpr *NestedAR = dyn_cast<SCEVAddRecExpr>(Operands[0])) { |
| 2667 | const Loop *NestedLoop = NestedAR->getLoop(); |
| 2668 | if (L->contains(NestedLoop) ? |
| 2669 | (L->getLoopDepth() < NestedLoop->getLoopDepth()) : |
| 2670 | (!NestedLoop->contains(L) && |
| 2671 | DT->dominates(L->getHeader(), NestedLoop->getHeader()))) { |
| 2672 | SmallVector<const SCEV *, 4> NestedOperands(NestedAR->op_begin(), |
| 2673 | NestedAR->op_end()); |
| 2674 | Operands[0] = NestedAR->getStart(); |
| 2675 | // AddRecs require their operands be loop-invariant with respect to their |
| 2676 | // loops. Don't perform this transformation if it would break this |
| 2677 | // requirement. |
| 2678 | bool AllInvariant = true; |
| 2679 | for (unsigned i = 0, e = Operands.size(); i != e; ++i) |
| 2680 | if (!isLoopInvariant(Operands[i], L)) { |
| 2681 | AllInvariant = false; |
| 2682 | break; |
| 2683 | } |
| 2684 | if (AllInvariant) { |
| 2685 | // Create a recurrence for the outer loop with the same step size. |
| 2686 | // |
| 2687 | // The outer recurrence keeps its NW flag but only keeps NUW/NSW if the |
| 2688 | // inner recurrence has the same property. |
| 2689 | SCEV::NoWrapFlags OuterFlags = |
| 2690 | maskFlags(Flags, SCEV::FlagNW | NestedAR->getNoWrapFlags()); |
| 2691 | |
| 2692 | NestedOperands[0] = getAddRecExpr(Operands, L, OuterFlags); |
| 2693 | AllInvariant = true; |
| 2694 | for (unsigned i = 0, e = NestedOperands.size(); i != e; ++i) |
| 2695 | if (!isLoopInvariant(NestedOperands[i], NestedLoop)) { |
| 2696 | AllInvariant = false; |
| 2697 | break; |
| 2698 | } |
| 2699 | if (AllInvariant) { |
| 2700 | // Ok, both add recurrences are valid after the transformation. |
| 2701 | // |
| 2702 | // The inner recurrence keeps its NW flag but only keeps NUW/NSW if |
| 2703 | // the outer recurrence has the same property. |
| 2704 | SCEV::NoWrapFlags InnerFlags = |
| 2705 | maskFlags(NestedAR->getNoWrapFlags(), SCEV::FlagNW | Flags); |
| 2706 | return getAddRecExpr(NestedOperands, NestedLoop, InnerFlags); |
| 2707 | } |
| 2708 | } |
| 2709 | // Reset Operands to its original state. |
| 2710 | Operands[0] = NestedAR; |
| 2711 | } |
| 2712 | } |
| 2713 | |
| 2714 | // Okay, it looks like we really DO need an addrec expr. Check to see if we |
| 2715 | // already have one, otherwise create a new one. |
| 2716 | FoldingSetNodeID ID; |
| 2717 | ID.AddInteger(scAddRecExpr); |
| 2718 | for (unsigned i = 0, e = Operands.size(); i != e; ++i) |
| 2719 | ID.AddPointer(Operands[i]); |
| 2720 | ID.AddPointer(L); |
| 2721 | void *IP = nullptr; |
| 2722 | SCEVAddRecExpr *S = |
| 2723 | static_cast<SCEVAddRecExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP)); |
| 2724 | if (!S) { |
| 2725 | const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Operands.size()); |
| 2726 | std::uninitialized_copy(Operands.begin(), Operands.end(), O); |
| 2727 | S = new (SCEVAllocator) SCEVAddRecExpr(ID.Intern(SCEVAllocator), |
| 2728 | O, Operands.size(), L); |
| 2729 | UniqueSCEVs.InsertNode(S, IP); |
| 2730 | } |
| 2731 | S->setNoWrapFlags(Flags); |
| 2732 | return S; |
| 2733 | } |
| 2734 | |
| 2735 | const SCEV *ScalarEvolution::getSMaxExpr(const SCEV *LHS, |
| 2736 | const SCEV *RHS) { |
| 2737 | SmallVector<const SCEV *, 2> Ops; |
| 2738 | Ops.push_back(LHS); |
| 2739 | Ops.push_back(RHS); |
| 2740 | return getSMaxExpr(Ops); |
| 2741 | } |
| 2742 | |
| 2743 | const SCEV * |
| 2744 | ScalarEvolution::getSMaxExpr(SmallVectorImpl<const SCEV *> &Ops) { |
| 2745 | assert(!Ops.empty() && "Cannot get empty smax!")((!Ops.empty() && "Cannot get empty smax!") ? static_cast <void> (0) : __assert_fail ("!Ops.empty() && \"Cannot get empty smax!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 2745, __PRETTY_FUNCTION__)); |
| 2746 | if (Ops.size() == 1) return Ops[0]; |
| 2747 | #ifndef NDEBUG |
| 2748 | Type *ETy = getEffectiveSCEVType(Ops[0]->getType()); |
| 2749 | for (unsigned i = 1, e = Ops.size(); i != e; ++i) |
| 2750 | assert(getEffectiveSCEVType(Ops[i]->getType()) == ETy &&((getEffectiveSCEVType(Ops[i]->getType()) == ETy && "SCEVSMaxExpr operand types don't match!") ? static_cast< void> (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVSMaxExpr operand types don't match!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 2751, __PRETTY_FUNCTION__)) |
| 2751 | "SCEVSMaxExpr operand types don't match!")((getEffectiveSCEVType(Ops[i]->getType()) == ETy && "SCEVSMaxExpr operand types don't match!") ? static_cast< void> (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVSMaxExpr operand types don't match!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 2751, __PRETTY_FUNCTION__)); |
| 2752 | #endif |
| 2753 | |
| 2754 | // Sort by complexity, this groups all similar expression types together. |
| 2755 | GroupByComplexity(Ops, LI); |
| 2756 | |
| 2757 | // If there are any constants, fold them together. |
| 2758 | unsigned Idx = 0; |
| 2759 | if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) { |
| 2760 | ++Idx; |
| 2761 | assert(Idx < Ops.size())((Idx < Ops.size()) ? static_cast<void> (0) : __assert_fail ("Idx < Ops.size()", "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 2761, __PRETTY_FUNCTION__)); |
| 2762 | while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) { |
| 2763 | // We found two constants, fold them together! |
| 2764 | ConstantInt *Fold = ConstantInt::get(getContext(), |
| 2765 | APIntOps::smax(LHSC->getValue()->getValue(), |
| 2766 | RHSC->getValue()->getValue())); |
| 2767 | Ops[0] = getConstant(Fold); |
| 2768 | Ops.erase(Ops.begin()+1); // Erase the folded element |
| 2769 | if (Ops.size() == 1) return Ops[0]; |
| 2770 | LHSC = cast<SCEVConstant>(Ops[0]); |
| 2771 | } |
| 2772 | |
| 2773 | // If we are left with a constant minimum-int, strip it off. |
| 2774 | if (cast<SCEVConstant>(Ops[0])->getValue()->isMinValue(true)) { |
| 2775 | Ops.erase(Ops.begin()); |
| 2776 | --Idx; |
| 2777 | } else if (cast<SCEVConstant>(Ops[0])->getValue()->isMaxValue(true)) { |
| 2778 | // If we have an smax with a constant maximum-int, it will always be |
| 2779 | // maximum-int. |
| 2780 | return Ops[0]; |
| 2781 | } |
| 2782 | |
| 2783 | if (Ops.size() == 1) return Ops[0]; |
| 2784 | } |
| 2785 | |
| 2786 | // Find the first SMax |
| 2787 | while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scSMaxExpr) |
| 2788 | ++Idx; |
| 2789 | |
| 2790 | // Check to see if one of the operands is an SMax. If so, expand its operands |
| 2791 | // onto our operand list, and recurse to simplify. |
| 2792 | if (Idx < Ops.size()) { |
| 2793 | bool DeletedSMax = false; |
| 2794 | while (const SCEVSMaxExpr *SMax = dyn_cast<SCEVSMaxExpr>(Ops[Idx])) { |
| 2795 | Ops.erase(Ops.begin()+Idx); |
| 2796 | Ops.append(SMax->op_begin(), SMax->op_end()); |
| 2797 | DeletedSMax = true; |
| 2798 | } |
| 2799 | |
| 2800 | if (DeletedSMax) |
| 2801 | return getSMaxExpr(Ops); |
| 2802 | } |
| 2803 | |
| 2804 | // Okay, check to see if the same value occurs in the operand list twice. If |
| 2805 | // so, delete one. Since we sorted the list, these values are required to |
| 2806 | // be adjacent. |
| 2807 | for (unsigned i = 0, e = Ops.size()-1; i != e; ++i) |
| 2808 | // X smax Y smax Y --> X smax Y |
| 2809 | // X smax Y --> X, if X is always greater than Y |
| 2810 | if (Ops[i] == Ops[i+1] || |
| 2811 | isKnownPredicate(ICmpInst::ICMP_SGE, Ops[i], Ops[i+1])) { |
| 2812 | Ops.erase(Ops.begin()+i+1, Ops.begin()+i+2); |
| 2813 | --i; --e; |
| 2814 | } else if (isKnownPredicate(ICmpInst::ICMP_SLE, Ops[i], Ops[i+1])) { |
| 2815 | Ops.erase(Ops.begin()+i, Ops.begin()+i+1); |
| 2816 | --i; --e; |
| 2817 | } |
| 2818 | |
| 2819 | if (Ops.size() == 1) return Ops[0]; |
| 2820 | |
| 2821 | assert(!Ops.empty() && "Reduced smax down to nothing!")((!Ops.empty() && "Reduced smax down to nothing!") ? static_cast <void> (0) : __assert_fail ("!Ops.empty() && \"Reduced smax down to nothing!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 2821, __PRETTY_FUNCTION__)); |
| 2822 | |
| 2823 | // Okay, it looks like we really DO need an smax expr. Check to see if we |
| 2824 | // already have one, otherwise create a new one. |
| 2825 | FoldingSetNodeID ID; |
| 2826 | ID.AddInteger(scSMaxExpr); |
| 2827 | for (unsigned i = 0, e = Ops.size(); i != e; ++i) |
| 2828 | ID.AddPointer(Ops[i]); |
| 2829 | void *IP = nullptr; |
| 2830 | if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S; |
| 2831 | const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size()); |
| 2832 | std::uninitialized_copy(Ops.begin(), Ops.end(), O); |
| 2833 | SCEV *S = new (SCEVAllocator) SCEVSMaxExpr(ID.Intern(SCEVAllocator), |
| 2834 | O, Ops.size()); |
| 2835 | UniqueSCEVs.InsertNode(S, IP); |
| 2836 | return S; |
| 2837 | } |
| 2838 | |
| 2839 | const SCEV *ScalarEvolution::getUMaxExpr(const SCEV *LHS, |
| 2840 | const SCEV *RHS) { |
| 2841 | SmallVector<const SCEV *, 2> Ops; |
| 2842 | Ops.push_back(LHS); |
| 2843 | Ops.push_back(RHS); |
| 2844 | return getUMaxExpr(Ops); |
| 2845 | } |
| 2846 | |
| 2847 | const SCEV * |
| 2848 | ScalarEvolution::getUMaxExpr(SmallVectorImpl<const SCEV *> &Ops) { |
| 2849 | assert(!Ops.empty() && "Cannot get empty umax!")((!Ops.empty() && "Cannot get empty umax!") ? static_cast <void> (0) : __assert_fail ("!Ops.empty() && \"Cannot get empty umax!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 2849, __PRETTY_FUNCTION__)); |
| 2850 | if (Ops.size() == 1) return Ops[0]; |
| 2851 | #ifndef NDEBUG |
| 2852 | Type *ETy = getEffectiveSCEVType(Ops[0]->getType()); |
| 2853 | for (unsigned i = 1, e = Ops.size(); i != e; ++i) |
| 2854 | assert(getEffectiveSCEVType(Ops[i]->getType()) == ETy &&((getEffectiveSCEVType(Ops[i]->getType()) == ETy && "SCEVUMaxExpr operand types don't match!") ? static_cast< void> (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVUMaxExpr operand types don't match!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 2855, __PRETTY_FUNCTION__)) |
| 2855 | "SCEVUMaxExpr operand types don't match!")((getEffectiveSCEVType(Ops[i]->getType()) == ETy && "SCEVUMaxExpr operand types don't match!") ? static_cast< void> (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVUMaxExpr operand types don't match!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 2855, __PRETTY_FUNCTION__)); |
| 2856 | #endif |
| 2857 | |
| 2858 | // Sort by complexity, this groups all similar expression types together. |
| 2859 | GroupByComplexity(Ops, LI); |
| 2860 | |
| 2861 | // If there are any constants, fold them together. |
| 2862 | unsigned Idx = 0; |
| 2863 | if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) { |
| 2864 | ++Idx; |
| 2865 | assert(Idx < Ops.size())((Idx < Ops.size()) ? static_cast<void> (0) : __assert_fail ("Idx < Ops.size()", "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 2865, __PRETTY_FUNCTION__)); |
| 2866 | while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) { |
| 2867 | // We found two constants, fold them together! |
| 2868 | ConstantInt *Fold = ConstantInt::get(getContext(), |
| 2869 | APIntOps::umax(LHSC->getValue()->getValue(), |
| 2870 | RHSC->getValue()->getValue())); |
| 2871 | Ops[0] = getConstant(Fold); |
| 2872 | Ops.erase(Ops.begin()+1); // Erase the folded element |
| 2873 | if (Ops.size() == 1) return Ops[0]; |
| 2874 | LHSC = cast<SCEVConstant>(Ops[0]); |
| 2875 | } |
| 2876 | |
| 2877 | // If we are left with a constant minimum-int, strip it off. |
| 2878 | if (cast<SCEVConstant>(Ops[0])->getValue()->isMinValue(false)) { |
| 2879 | Ops.erase(Ops.begin()); |
| 2880 | --Idx; |
| 2881 | } else if (cast<SCEVConstant>(Ops[0])->getValue()->isMaxValue(false)) { |
| 2882 | // If we have an umax with a constant maximum-int, it will always be |
| 2883 | // maximum-int. |
| 2884 | return Ops[0]; |
| 2885 | } |
| 2886 | |
| 2887 | if (Ops.size() == 1) return Ops[0]; |
| 2888 | } |
| 2889 | |
| 2890 | // Find the first UMax |
| 2891 | while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scUMaxExpr) |
| 2892 | ++Idx; |
| 2893 | |
| 2894 | // Check to see if one of the operands is a UMax. If so, expand its operands |
| 2895 | // onto our operand list, and recurse to simplify. |
| 2896 | if (Idx < Ops.size()) { |
| 2897 | bool DeletedUMax = false; |
| 2898 | while (const SCEVUMaxExpr *UMax = dyn_cast<SCEVUMaxExpr>(Ops[Idx])) { |
| 2899 | Ops.erase(Ops.begin()+Idx); |
| 2900 | Ops.append(UMax->op_begin(), UMax->op_end()); |
| 2901 | DeletedUMax = true; |
| 2902 | } |
| 2903 | |
| 2904 | if (DeletedUMax) |
| 2905 | return getUMaxExpr(Ops); |
| 2906 | } |
| 2907 | |
| 2908 | // Okay, check to see if the same value occurs in the operand list twice. If |
| 2909 | // so, delete one. Since we sorted the list, these values are required to |
| 2910 | // be adjacent. |
| 2911 | for (unsigned i = 0, e = Ops.size()-1; i != e; ++i) |
| 2912 | // X umax Y umax Y --> X umax Y |
| 2913 | // X umax Y --> X, if X is always greater than Y |
| 2914 | if (Ops[i] == Ops[i+1] || |
| 2915 | isKnownPredicate(ICmpInst::ICMP_UGE, Ops[i], Ops[i+1])) { |
| 2916 | Ops.erase(Ops.begin()+i+1, Ops.begin()+i+2); |
| 2917 | --i; --e; |
| 2918 | } else if (isKnownPredicate(ICmpInst::ICMP_ULE, Ops[i], Ops[i+1])) { |
| 2919 | Ops.erase(Ops.begin()+i, Ops.begin()+i+1); |
| 2920 | --i; --e; |
| 2921 | } |
| 2922 | |
| 2923 | if (Ops.size() == 1) return Ops[0]; |
| 2924 | |
| 2925 | assert(!Ops.empty() && "Reduced umax down to nothing!")((!Ops.empty() && "Reduced umax down to nothing!") ? static_cast <void> (0) : __assert_fail ("!Ops.empty() && \"Reduced umax down to nothing!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 2925, __PRETTY_FUNCTION__)); |
| 2926 | |
| 2927 | // Okay, it looks like we really DO need a umax expr. Check to see if we |
| 2928 | // already have one, otherwise create a new one. |
| 2929 | FoldingSetNodeID ID; |
| 2930 | ID.AddInteger(scUMaxExpr); |
| 2931 | for (unsigned i = 0, e = Ops.size(); i != e; ++i) |
| 2932 | ID.AddPointer(Ops[i]); |
| 2933 | void *IP = nullptr; |
| 2934 | if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S; |
| 2935 | const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size()); |
| 2936 | std::uninitialized_copy(Ops.begin(), Ops.end(), O); |
| 2937 | SCEV *S = new (SCEVAllocator) SCEVUMaxExpr(ID.Intern(SCEVAllocator), |
| 2938 | O, Ops.size()); |
| 2939 | UniqueSCEVs.InsertNode(S, IP); |
| 2940 | return S; |
| 2941 | } |
| 2942 | |
| 2943 | const SCEV *ScalarEvolution::getSMinExpr(const SCEV *LHS, |
| 2944 | const SCEV *RHS) { |
| 2945 | // ~smax(~x, ~y) == smin(x, y). |
| 2946 | return getNotSCEV(getSMaxExpr(getNotSCEV(LHS), getNotSCEV(RHS))); |
| 2947 | } |
| 2948 | |
| 2949 | const SCEV *ScalarEvolution::getUMinExpr(const SCEV *LHS, |
| 2950 | const SCEV *RHS) { |
| 2951 | // ~umax(~x, ~y) == umin(x, y) |
| 2952 | return getNotSCEV(getUMaxExpr(getNotSCEV(LHS), getNotSCEV(RHS))); |
| 2953 | } |
| 2954 | |
| 2955 | const SCEV *ScalarEvolution::getSizeOfExpr(Type *IntTy, Type *AllocTy) { |
| 2956 | // If we have DataLayout, we can bypass creating a target-independent |
| 2957 | // constant expression and then folding it back into a ConstantInt. |
| 2958 | // This is just a compile-time optimization. |
| 2959 | if (DL) |
| 2960 | return getConstant(IntTy, DL->getTypeAllocSize(AllocTy)); |
| 2961 | |
| 2962 | Constant *C = ConstantExpr::getSizeOf(AllocTy); |
| 2963 | if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) |
| 2964 | if (Constant *Folded = ConstantFoldConstantExpression(CE, DL, TLI)) |
| 2965 | C = Folded; |
| 2966 | Type *Ty = getEffectiveSCEVType(PointerType::getUnqual(AllocTy)); |
| 2967 | assert(Ty == IntTy && "Effective SCEV type doesn't match")((Ty == IntTy && "Effective SCEV type doesn't match") ? static_cast<void> (0) : __assert_fail ("Ty == IntTy && \"Effective SCEV type doesn't match\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 2967, __PRETTY_FUNCTION__)); |
| 2968 | return getTruncateOrZeroExtend(getSCEV(C), Ty); |
| 2969 | } |
| 2970 | |
| 2971 | const SCEV *ScalarEvolution::getOffsetOfExpr(Type *IntTy, |
| 2972 | StructType *STy, |
| 2973 | unsigned FieldNo) { |
| 2974 | // If we have DataLayout, we can bypass creating a target-independent |
| 2975 | // constant expression and then folding it back into a ConstantInt. |
| 2976 | // This is just a compile-time optimization. |
| 2977 | if (DL) { |
| 2978 | return getConstant(IntTy, |
| 2979 | DL->getStructLayout(STy)->getElementOffset(FieldNo)); |
| 2980 | } |
| 2981 | |
| 2982 | Constant *C = ConstantExpr::getOffsetOf(STy, FieldNo); |
| 2983 | if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) |
| 2984 | if (Constant *Folded = ConstantFoldConstantExpression(CE, DL, TLI)) |
| 2985 | C = Folded; |
| 2986 | |
| 2987 | Type *Ty = getEffectiveSCEVType(PointerType::getUnqual(STy)); |
| 2988 | return getTruncateOrZeroExtend(getSCEV(C), Ty); |
| 2989 | } |
| 2990 | |
| 2991 | const SCEV *ScalarEvolution::getUnknown(Value *V) { |
| 2992 | // Don't attempt to do anything other than create a SCEVUnknown object |
| 2993 | // here. createSCEV only calls getUnknown after checking for all other |
| 2994 | // interesting possibilities, and any other code that calls getUnknown |
| 2995 | // is doing so in order to hide a value from SCEV canonicalization. |
| 2996 | |
| 2997 | FoldingSetNodeID ID; |
| 2998 | ID.AddInteger(scUnknown); |
| 2999 | ID.AddPointer(V); |
| 3000 | void *IP = nullptr; |
| 3001 | if (SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) { |
| 3002 | assert(cast<SCEVUnknown>(S)->getValue() == V &&((cast<SCEVUnknown>(S)->getValue() == V && "Stale SCEVUnknown in uniquing map!" ) ? static_cast<void> (0) : __assert_fail ("cast<SCEVUnknown>(S)->getValue() == V && \"Stale SCEVUnknown in uniquing map!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 3003, __PRETTY_FUNCTION__)) |
| 3003 | "Stale SCEVUnknown in uniquing map!")((cast<SCEVUnknown>(S)->getValue() == V && "Stale SCEVUnknown in uniquing map!" ) ? static_cast<void> (0) : __assert_fail ("cast<SCEVUnknown>(S)->getValue() == V && \"Stale SCEVUnknown in uniquing map!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 3003, __PRETTY_FUNCTION__)); |
| 3004 | return S; |
| 3005 | } |
| 3006 | SCEV *S = new (SCEVAllocator) SCEVUnknown(ID.Intern(SCEVAllocator), V, this, |
| 3007 | FirstUnknown); |
| 3008 | FirstUnknown = cast<SCEVUnknown>(S); |
| 3009 | UniqueSCEVs.InsertNode(S, IP); |
| 3010 | return S; |
| 3011 | } |
| 3012 | |
| 3013 | //===----------------------------------------------------------------------===// |
| 3014 | // Basic SCEV Analysis and PHI Idiom Recognition Code |
| 3015 | // |
| 3016 | |
| 3017 | /// isSCEVable - Test if values of the given type are analyzable within |
| 3018 | /// the SCEV framework. This primarily includes integer types, and it |
| 3019 | /// can optionally include pointer types if the ScalarEvolution class |
| 3020 | /// has access to target-specific information. |
| 3021 | bool ScalarEvolution::isSCEVable(Type *Ty) const { |
| 3022 | // Integers and pointers are always SCEVable. |
| 3023 | return Ty->isIntegerTy() || Ty->isPointerTy(); |
| 3024 | } |
| 3025 | |
| 3026 | /// getTypeSizeInBits - Return the size in bits of the specified type, |
| 3027 | /// for which isSCEVable must return true. |
| 3028 | uint64_t ScalarEvolution::getTypeSizeInBits(Type *Ty) const { |
| 3029 | assert(isSCEVable(Ty) && "Type is not SCEVable!")((isSCEVable(Ty) && "Type is not SCEVable!") ? static_cast <void> (0) : __assert_fail ("isSCEVable(Ty) && \"Type is not SCEVable!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 3029, __PRETTY_FUNCTION__)); |
| 3030 | |
| 3031 | // If we have a DataLayout, use it! |
| 3032 | if (DL) |
| 3033 | return DL->getTypeSizeInBits(Ty); |
| 3034 | |
| 3035 | // Integer types have fixed sizes. |
| 3036 | if (Ty->isIntegerTy()) |
| 3037 | return Ty->getPrimitiveSizeInBits(); |
| 3038 | |
| 3039 | // The only other support type is pointer. Without DataLayout, conservatively |
| 3040 | // assume pointers are 64-bit. |
| 3041 | assert(Ty->isPointerTy() && "isSCEVable permitted a non-SCEVable type!")((Ty->isPointerTy() && "isSCEVable permitted a non-SCEVable type!" ) ? static_cast<void> (0) : __assert_fail ("Ty->isPointerTy() && \"isSCEVable permitted a non-SCEVable type!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 3041, __PRETTY_FUNCTION__)); |
| 3042 | return 64; |
| 3043 | } |
| 3044 | |
| 3045 | /// getEffectiveSCEVType - Return a type with the same bitwidth as |
| 3046 | /// the given type and which represents how SCEV will treat the given |
| 3047 | /// type, for which isSCEVable must return true. For pointer types, |
| 3048 | /// this is the pointer-sized integer type. |
| 3049 | Type *ScalarEvolution::getEffectiveSCEVType(Type *Ty) const { |
| 3050 | assert(isSCEVable(Ty) && "Type is not SCEVable!")((isSCEVable(Ty) && "Type is not SCEVable!") ? static_cast <void> (0) : __assert_fail ("isSCEVable(Ty) && \"Type is not SCEVable!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 3050, __PRETTY_FUNCTION__)); |
| 3051 | |
| 3052 | if (Ty->isIntegerTy()) { |
| 3053 | return Ty; |
| 3054 | } |
| 3055 | |
| 3056 | // The only other support type is pointer. |
| 3057 | assert(Ty->isPointerTy() && "Unexpected non-pointer non-integer type!")((Ty->isPointerTy() && "Unexpected non-pointer non-integer type!" ) ? static_cast<void> (0) : __assert_fail ("Ty->isPointerTy() && \"Unexpected non-pointer non-integer type!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 3057, __PRETTY_FUNCTION__)); |
| 3058 | |
| 3059 | if (DL) |
| 3060 | return DL->getIntPtrType(Ty); |
| 3061 | |
| 3062 | // Without DataLayout, conservatively assume pointers are 64-bit. |
| 3063 | return Type::getInt64Ty(getContext()); |
| 3064 | } |
| 3065 | |
| 3066 | const SCEV *ScalarEvolution::getCouldNotCompute() { |
| 3067 | return &CouldNotCompute; |
| 3068 | } |
| 3069 | |
| 3070 | namespace { |
| 3071 | // Helper class working with SCEVTraversal to figure out if a SCEV contains |
| 3072 | // a SCEVUnknown with null value-pointer. FindInvalidSCEVUnknown::FindOne |
| 3073 | // is set iff if find such SCEVUnknown. |
| 3074 | // |
| 3075 | struct FindInvalidSCEVUnknown { |
| 3076 | bool FindOne; |
| 3077 | FindInvalidSCEVUnknown() { FindOne = false; } |
| 3078 | bool follow(const SCEV *S) { |
| 3079 | switch (static_cast<SCEVTypes>(S->getSCEVType())) { |
| 3080 | case scConstant: |
| 3081 | return false; |
| 3082 | case scUnknown: |
| 3083 | if (!cast<SCEVUnknown>(S)->getValue()) |
| 3084 | FindOne = true; |
| 3085 | return false; |
| 3086 | default: |
| 3087 | return true; |
| 3088 | } |
| 3089 | } |
| 3090 | bool isDone() const { return FindOne; } |
| 3091 | }; |
| 3092 | } |
| 3093 | |
| 3094 | bool ScalarEvolution::checkValidity(const SCEV *S) const { |
| 3095 | FindInvalidSCEVUnknown F; |
| 3096 | SCEVTraversal<FindInvalidSCEVUnknown> ST(F); |
| 3097 | ST.visitAll(S); |
| 3098 | |
| 3099 | return !F.FindOne; |
| 3100 | } |
| 3101 | |
| 3102 | /// getSCEV - Return an existing SCEV if it exists, otherwise analyze the |
| 3103 | /// expression and create a new one. |
| 3104 | const SCEV *ScalarEvolution::getSCEV(Value *V) { |
| 3105 | assert(isSCEVable(V->getType()) && "Value is not SCEVable!")((isSCEVable(V->getType()) && "Value is not SCEVable!" ) ? static_cast<void> (0) : __assert_fail ("isSCEVable(V->getType()) && \"Value is not SCEVable!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 3105, __PRETTY_FUNCTION__)); |
| 3106 | |
| 3107 | ValueExprMapType::iterator I = ValueExprMap.find_as(V); |
| 3108 | if (I != ValueExprMap.end()) { |
| 3109 | const SCEV *S = I->second; |
| 3110 | if (checkValidity(S)) |
| 3111 | return S; |
| 3112 | else |
| 3113 | ValueExprMap.erase(I); |
| 3114 | } |
| 3115 | const SCEV *S = createSCEV(V); |
| 3116 | |
| 3117 | // The process of creating a SCEV for V may have caused other SCEVs |
| 3118 | // to have been created, so it's necessary to insert the new entry |
| 3119 | // from scratch, rather than trying to remember the insert position |
| 3120 | // above. |
| 3121 | ValueExprMap.insert(std::make_pair(SCEVCallbackVH(V, this), S)); |
| 3122 | return S; |
| 3123 | } |
| 3124 | |
| 3125 | /// getNegativeSCEV - Return a SCEV corresponding to -V = -1*V |
| 3126 | /// |
| 3127 | const SCEV *ScalarEvolution::getNegativeSCEV(const SCEV *V) { |
| 3128 | if (const SCEVConstant *VC = dyn_cast<SCEVConstant>(V)) |
| 3129 | return getConstant( |
| 3130 | cast<ConstantInt>(ConstantExpr::getNeg(VC->getValue()))); |
| 3131 | |
| 3132 | Type *Ty = V->getType(); |
| 3133 | Ty = getEffectiveSCEVType(Ty); |
| 3134 | return getMulExpr(V, |
| 3135 | getConstant(cast<ConstantInt>(Constant::getAllOnesValue(Ty)))); |
| 3136 | } |
| 3137 | |
| 3138 | /// getNotSCEV - Return a SCEV corresponding to ~V = -1-V |
| 3139 | const SCEV *ScalarEvolution::getNotSCEV(const SCEV *V) { |
| 3140 | if (const SCEVConstant *VC = dyn_cast<SCEVConstant>(V)) |
| 3141 | return getConstant( |
| 3142 | cast<ConstantInt>(ConstantExpr::getNot(VC->getValue()))); |
| 3143 | |
| 3144 | Type *Ty = V->getType(); |
| 3145 | Ty = getEffectiveSCEVType(Ty); |
| 3146 | const SCEV *AllOnes = |
| 3147 | getConstant(cast<ConstantInt>(Constant::getAllOnesValue(Ty))); |
| 3148 | return getMinusSCEV(AllOnes, V); |
| 3149 | } |
| 3150 | |
| 3151 | /// getMinusSCEV - Return LHS-RHS. Minus is represented in SCEV as A+B*-1. |
| 3152 | const SCEV *ScalarEvolution::getMinusSCEV(const SCEV *LHS, const SCEV *RHS, |
| 3153 | SCEV::NoWrapFlags Flags) { |
| 3154 | assert(!maskFlags(Flags, SCEV::FlagNUW) && "subtraction does not have NUW")((!maskFlags(Flags, SCEV::FlagNUW) && "subtraction does not have NUW" ) ? static_cast<void> (0) : __assert_fail ("!maskFlags(Flags, SCEV::FlagNUW) && \"subtraction does not have NUW\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 3154, __PRETTY_FUNCTION__)); |
| 3155 | |
| 3156 | // Fast path: X - X --> 0. |
| 3157 | if (LHS == RHS) |
| 3158 | return getConstant(LHS->getType(), 0); |
| 3159 | |
| 3160 | // X - Y --> X + -Y |
| 3161 | return getAddExpr(LHS, getNegativeSCEV(RHS), Flags); |
| 3162 | } |
| 3163 | |
| 3164 | /// getTruncateOrZeroExtend - Return a SCEV corresponding to a conversion of the |
| 3165 | /// input value to the specified type. If the type must be extended, it is zero |
| 3166 | /// extended. |
| 3167 | const SCEV * |
| 3168 | ScalarEvolution::getTruncateOrZeroExtend(const SCEV *V, Type *Ty) { |
| 3169 | Type *SrcTy = V->getType(); |
| 3170 | assert((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot truncate or zero extend with non-integer arguments!" ) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot truncate or zero extend with non-integer arguments!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 3172, __PRETTY_FUNCTION__)) |
| 3171 | (Ty->isIntegerTy() || Ty->isPointerTy()) &&(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot truncate or zero extend with non-integer arguments!" ) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot truncate or zero extend with non-integer arguments!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 3172, __PRETTY_FUNCTION__)) |
| 3172 | "Cannot truncate or zero extend with non-integer arguments!")(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot truncate or zero extend with non-integer arguments!" ) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot truncate or zero extend with non-integer arguments!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 3172, __PRETTY_FUNCTION__)); |
| 3173 | if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty)) |
| 3174 | return V; // No conversion |
| 3175 | if (getTypeSizeInBits(SrcTy) > getTypeSizeInBits(Ty)) |
| 3176 | return getTruncateExpr(V, Ty); |
| 3177 | return getZeroExtendExpr(V, Ty); |
| 3178 | } |
| 3179 | |
| 3180 | /// getTruncateOrSignExtend - Return a SCEV corresponding to a conversion of the |
| 3181 | /// input value to the specified type. If the type must be extended, it is sign |
| 3182 | /// extended. |
| 3183 | const SCEV * |
| 3184 | ScalarEvolution::getTruncateOrSignExtend(const SCEV *V, |
| 3185 | Type *Ty) { |
| 3186 | Type *SrcTy = V->getType(); |
| 3187 | assert((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot truncate or zero extend with non-integer arguments!" ) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot truncate or zero extend with non-integer arguments!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 3189, __PRETTY_FUNCTION__)) |
| 3188 | (Ty->isIntegerTy() || Ty->isPointerTy()) &&(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot truncate or zero extend with non-integer arguments!" ) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot truncate or zero extend with non-integer arguments!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 3189, __PRETTY_FUNCTION__)) |
| 3189 | "Cannot truncate or zero extend with non-integer arguments!")(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot truncate or zero extend with non-integer arguments!" ) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot truncate or zero extend with non-integer arguments!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 3189, __PRETTY_FUNCTION__)); |
| 3190 | if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty)) |
| 3191 | return V; // No conversion |
| 3192 | if (getTypeSizeInBits(SrcTy) > getTypeSizeInBits(Ty)) |
| 3193 | return getTruncateExpr(V, Ty); |
| 3194 | return getSignExtendExpr(V, Ty); |
| 3195 | } |
| 3196 | |
| 3197 | /// getNoopOrZeroExtend - Return a SCEV corresponding to a conversion of the |
| 3198 | /// input value to the specified type. If the type must be extended, it is zero |
| 3199 | /// extended. The conversion must not be narrowing. |
| 3200 | const SCEV * |
| 3201 | ScalarEvolution::getNoopOrZeroExtend(const SCEV *V, Type *Ty) { |
| 3202 | Type *SrcTy = V->getType(); |
| 3203 | assert((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot noop or zero extend with non-integer arguments!" ) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot noop or zero extend with non-integer arguments!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 3205, __PRETTY_FUNCTION__)) |
| 3204 | (Ty->isIntegerTy() || Ty->isPointerTy()) &&(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot noop or zero extend with non-integer arguments!" ) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot noop or zero extend with non-integer arguments!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 3205, __PRETTY_FUNCTION__)) |
| 3205 | "Cannot noop or zero extend with non-integer arguments!")(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot noop or zero extend with non-integer arguments!" ) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot noop or zero extend with non-integer arguments!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 3205, __PRETTY_FUNCTION__)); |
| 3206 | assert(getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) &&((getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && "getNoopOrZeroExtend cannot truncate!") ? static_cast<void > (0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrZeroExtend cannot truncate!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 3207, __PRETTY_FUNCTION__)) |
| 3207 | "getNoopOrZeroExtend cannot truncate!")((getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && "getNoopOrZeroExtend cannot truncate!") ? static_cast<void > (0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrZeroExtend cannot truncate!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 3207, __PRETTY_FUNCTION__)); |
| 3208 | if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty)) |
| 3209 | return V; // No conversion |
| 3210 | return getZeroExtendExpr(V, Ty); |
| 3211 | } |
| 3212 | |
| 3213 | /// getNoopOrSignExtend - Return a SCEV corresponding to a conversion of the |
| 3214 | /// input value to the specified type. If the type must be extended, it is sign |
| 3215 | /// extended. The conversion must not be narrowing. |
| 3216 | const SCEV * |
| 3217 | ScalarEvolution::getNoopOrSignExtend(const SCEV *V, Type *Ty) { |
| 3218 | Type *SrcTy = V->getType(); |
| 3219 | assert((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot noop or sign extend with non-integer arguments!" ) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot noop or sign extend with non-integer arguments!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 3221, __PRETTY_FUNCTION__)) |
| 3220 | (Ty->isIntegerTy() || Ty->isPointerTy()) &&(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot noop or sign extend with non-integer arguments!" ) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot noop or sign extend with non-integer arguments!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 3221, __PRETTY_FUNCTION__)) |
| 3221 | "Cannot noop or sign extend with non-integer arguments!")(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot noop or sign extend with non-integer arguments!" ) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot noop or sign extend with non-integer arguments!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 3221, __PRETTY_FUNCTION__)); |
| 3222 | assert(getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) &&((getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && "getNoopOrSignExtend cannot truncate!") ? static_cast<void > (0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrSignExtend cannot truncate!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 3223, __PRETTY_FUNCTION__)) |
| 3223 | "getNoopOrSignExtend cannot truncate!")((getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && "getNoopOrSignExtend cannot truncate!") ? static_cast<void > (0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrSignExtend cannot truncate!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 3223, __PRETTY_FUNCTION__)); |
| 3224 | if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty)) |
| 3225 | return V; // No conversion |
| 3226 | return getSignExtendExpr(V, Ty); |
| 3227 | } |
| 3228 | |
| 3229 | /// getNoopOrAnyExtend - Return a SCEV corresponding to a conversion of |
| 3230 | /// the input value to the specified type. If the type must be extended, |
| 3231 | /// it is extended with unspecified bits. The conversion must not be |
| 3232 | /// narrowing. |
| 3233 | const SCEV * |
| 3234 | ScalarEvolution::getNoopOrAnyExtend(const SCEV *V, Type *Ty) { |
| 3235 | Type *SrcTy = V->getType(); |
| 3236 | assert((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot noop or any extend with non-integer arguments!" ) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot noop or any extend with non-integer arguments!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 3238, __PRETTY_FUNCTION__)) |
| 3237 | (Ty->isIntegerTy() || Ty->isPointerTy()) &&(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot noop or any extend with non-integer arguments!" ) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot noop or any extend with non-integer arguments!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 3238, __PRETTY_FUNCTION__)) |
| 3238 | "Cannot noop or any extend with non-integer arguments!")(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot noop or any extend with non-integer arguments!" ) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot noop or any extend with non-integer arguments!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 3238, __PRETTY_FUNCTION__)); |
| 3239 | assert(getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) &&((getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && "getNoopOrAnyExtend cannot truncate!") ? static_cast<void > (0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrAnyExtend cannot truncate!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 3240, __PRETTY_FUNCTION__)) |
| 3240 | "getNoopOrAnyExtend cannot truncate!")((getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && "getNoopOrAnyExtend cannot truncate!") ? static_cast<void > (0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrAnyExtend cannot truncate!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 3240, __PRETTY_FUNCTION__)); |
| 3241 | if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty)) |
| 3242 | return V; // No conversion |
| 3243 | return getAnyExtendExpr(V, Ty); |
| 3244 | } |
| 3245 | |
| 3246 | /// getTruncateOrNoop - Return a SCEV corresponding to a conversion of the |
| 3247 | /// input value to the specified type. The conversion must not be widening. |
| 3248 | const SCEV * |
| 3249 | ScalarEvolution::getTruncateOrNoop(const SCEV *V, Type *Ty) { |
| 3250 | Type *SrcTy = V->getType(); |
| 3251 | assert((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot truncate or noop with non-integer arguments!" ) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot truncate or noop with non-integer arguments!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 3253, __PRETTY_FUNCTION__)) |
| 3252 | (Ty->isIntegerTy() || Ty->isPointerTy()) &&(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot truncate or noop with non-integer arguments!" ) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot truncate or noop with non-integer arguments!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 3253, __PRETTY_FUNCTION__)) |
| 3253 | "Cannot truncate or noop with non-integer arguments!")(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot truncate or noop with non-integer arguments!" ) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot truncate or noop with non-integer arguments!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 3253, __PRETTY_FUNCTION__)); |
| 3254 | assert(getTypeSizeInBits(SrcTy) >= getTypeSizeInBits(Ty) &&((getTypeSizeInBits(SrcTy) >= getTypeSizeInBits(Ty) && "getTruncateOrNoop cannot extend!") ? static_cast<void> (0) : __assert_fail ("getTypeSizeInBits(SrcTy) >= getTypeSizeInBits(Ty) && \"getTruncateOrNoop cannot extend!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 3255, __PRETTY_FUNCTION__)) |
| 3255 | "getTruncateOrNoop cannot extend!")((getTypeSizeInBits(SrcTy) >= getTypeSizeInBits(Ty) && "getTruncateOrNoop cannot extend!") ? static_cast<void> (0) : __assert_fail ("getTypeSizeInBits(SrcTy) >= getTypeSizeInBits(Ty) && \"getTruncateOrNoop cannot extend!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 3255, __PRETTY_FUNCTION__)); |
| 3256 | if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty)) |
| 3257 | return V; // No conversion |
| 3258 | return getTruncateExpr(V, Ty); |
| 3259 | } |
| 3260 | |
| 3261 | /// getUMaxFromMismatchedTypes - Promote the operands to the wider of |
| 3262 | /// the types using zero-extension, and then perform a umax operation |
| 3263 | /// with them. |
| 3264 | const SCEV *ScalarEvolution::getUMaxFromMismatchedTypes(const SCEV *LHS, |
| 3265 | const SCEV *RHS) { |
| 3266 | const SCEV *PromotedLHS = LHS; |
| 3267 | const SCEV *PromotedRHS = RHS; |
| 3268 | |
| 3269 | if (getTypeSizeInBits(LHS->getType()) > getTypeSizeInBits(RHS->getType())) |
| 3270 | PromotedRHS = getZeroExtendExpr(RHS, LHS->getType()); |
| 3271 | else |
| 3272 | PromotedLHS = getNoopOrZeroExtend(LHS, RHS->getType()); |
| 3273 | |
| 3274 | return getUMaxExpr(PromotedLHS, PromotedRHS); |
| 3275 | } |
| 3276 | |
| 3277 | /// getUMinFromMismatchedTypes - Promote the operands to the wider of |
| 3278 | /// the types using zero-extension, and then perform a umin operation |
| 3279 | /// with them. |
| 3280 | const SCEV *ScalarEvolution::getUMinFromMismatchedTypes(const SCEV *LHS, |
| 3281 | const SCEV *RHS) { |
| 3282 | const SCEV *PromotedLHS = LHS; |
| 3283 | const SCEV *PromotedRHS = RHS; |
| 3284 | |
| 3285 | if (getTypeSizeInBits(LHS->getType()) > getTypeSizeInBits(RHS->getType())) |
| 3286 | PromotedRHS = getZeroExtendExpr(RHS, LHS->getType()); |
| 3287 | else |
| 3288 | PromotedLHS = getNoopOrZeroExtend(LHS, RHS->getType()); |
| 3289 | |
| 3290 | return getUMinExpr(PromotedLHS, PromotedRHS); |
| 3291 | } |
| 3292 | |
| 3293 | /// getPointerBase - Transitively follow the chain of pointer-type operands |
| 3294 | /// until reaching a SCEV that does not have a single pointer operand. This |
| 3295 | /// returns a SCEVUnknown pointer for well-formed pointer-type expressions, |
| 3296 | /// but corner cases do exist. |
| 3297 | const SCEV *ScalarEvolution::getPointerBase(const SCEV *V) { |
| 3298 | // A pointer operand may evaluate to a nonpointer expression, such as null. |
| 3299 | if (!V->getType()->isPointerTy()) |
| 3300 | return V; |
| 3301 | |
| 3302 | if (const SCEVCastExpr *Cast = dyn_cast<SCEVCastExpr>(V)) { |
| 3303 | return getPointerBase(Cast->getOperand()); |
| 3304 | } |
| 3305 | else if (const SCEVNAryExpr *NAry = dyn_cast<SCEVNAryExpr>(V)) { |
| 3306 | const SCEV *PtrOp = nullptr; |
| 3307 | for (SCEVNAryExpr::op_iterator I = NAry->op_begin(), E = NAry->op_end(); |
| 3308 | I != E; ++I) { |
| 3309 | if ((*I)->getType()->isPointerTy()) { |
| 3310 | // Cannot find the base of an expression with multiple pointer operands. |
| 3311 | if (PtrOp) |
| 3312 | return V; |
| 3313 | PtrOp = *I; |
| 3314 | } |
| 3315 | } |
| 3316 | if (!PtrOp) |
| 3317 | return V; |
| 3318 | return getPointerBase(PtrOp); |
| 3319 | } |
| 3320 | return V; |
| 3321 | } |
| 3322 | |
| 3323 | /// PushDefUseChildren - Push users of the given Instruction |
| 3324 | /// onto the given Worklist. |
| 3325 | static void |
| 3326 | PushDefUseChildren(Instruction *I, |
| 3327 | SmallVectorImpl<Instruction *> &Worklist) { |
| 3328 | // Push the def-use children onto the Worklist stack. |
| 3329 | for (User *U : I->users()) |
| 3330 | Worklist.push_back(cast<Instruction>(U)); |
| 3331 | } |
| 3332 | |
| 3333 | /// ForgetSymbolicValue - This looks up computed SCEV values for all |
| 3334 | /// instructions that depend on the given instruction and removes them from |
| 3335 | /// the ValueExprMapType map if they reference SymName. This is used during PHI |
| 3336 | /// resolution. |
| 3337 | void |
| 3338 | ScalarEvolution::ForgetSymbolicName(Instruction *PN, const SCEV *SymName) { |
| 3339 | SmallVector<Instruction *, 16> Worklist; |
| 3340 | PushDefUseChildren(PN, Worklist); |
| 3341 | |
| 3342 | SmallPtrSet<Instruction *, 8> Visited; |
| 3343 | Visited.insert(PN); |
| 3344 | while (!Worklist.empty()) { |
| 3345 | Instruction *I = Worklist.pop_back_val(); |
| 3346 | if (!Visited.insert(I)) continue; |
| 3347 | |
| 3348 | ValueExprMapType::iterator It = |
| 3349 | ValueExprMap.find_as(static_cast<Value *>(I)); |
| 3350 | if (It != ValueExprMap.end()) { |
| 3351 | const SCEV *Old = It->second; |
| 3352 | |
| 3353 | // Short-circuit the def-use traversal if the symbolic name |
| 3354 | // ceases to appear in expressions. |
| 3355 | if (Old != SymName && !hasOperand(Old, SymName)) |
| 3356 | continue; |
| 3357 | |
| 3358 | // SCEVUnknown for a PHI either means that it has an unrecognized |
| 3359 | // structure, it's a PHI that's in the progress of being computed |
| 3360 | // by createNodeForPHI, or it's a single-value PHI. In the first case, |
| 3361 | // additional loop trip count information isn't going to change anything. |
| 3362 | // In the second case, createNodeForPHI will perform the necessary |
| 3363 | // updates on its own when it gets to that point. In the third, we do |
| 3364 | // want to forget the SCEVUnknown. |
| 3365 | if (!isa<PHINode>(I) || |
| 3366 | !isa<SCEVUnknown>(Old) || |
| 3367 | (I != PN && Old == SymName)) { |
| 3368 | forgetMemoizedResults(Old); |
| 3369 | ValueExprMap.erase(It); |
| 3370 | } |
| 3371 | } |
| 3372 | |
| 3373 | PushDefUseChildren(I, Worklist); |
| 3374 | } |
| 3375 | } |
| 3376 | |
| 3377 | /// createNodeForPHI - PHI nodes have two cases. Either the PHI node exists in |
| 3378 | /// a loop header, making it a potential recurrence, or it doesn't. |
| 3379 | /// |
| 3380 | const SCEV *ScalarEvolution::createNodeForPHI(PHINode *PN) { |
| 3381 | if (const Loop *L = LI->getLoopFor(PN->getParent())) |
| 3382 | if (L->getHeader() == PN->getParent()) { |
| 3383 | // The loop may have multiple entrances or multiple exits; we can analyze |
| 3384 | // this phi as an addrec if it has a unique entry value and a unique |
| 3385 | // backedge value. |
| 3386 | Value *BEValueV = nullptr, *StartValueV = nullptr; |
| 3387 | for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) { |
| 3388 | Value *V = PN->getIncomingValue(i); |
| 3389 | if (L->contains(PN->getIncomingBlock(i))) { |
| 3390 | if (!BEValueV) { |
| 3391 | BEValueV = V; |
| 3392 | } else if (BEValueV != V) { |
| 3393 | BEValueV = nullptr; |
| 3394 | break; |
| 3395 | } |
| 3396 | } else if (!StartValueV) { |
| 3397 | StartValueV = V; |
| 3398 | } else if (StartValueV != V) { |
| 3399 | StartValueV = nullptr; |
| 3400 | break; |
| 3401 | } |
| 3402 | } |
| 3403 | if (BEValueV && StartValueV) { |
| 3404 | // While we are analyzing this PHI node, handle its value symbolically. |
| 3405 | const SCEV *SymbolicName = getUnknown(PN); |
| 3406 | assert(ValueExprMap.find_as(PN) == ValueExprMap.end() &&((ValueExprMap.find_as(PN) == ValueExprMap.end() && "PHI node already processed?" ) ? static_cast<void> (0) : __assert_fail ("ValueExprMap.find_as(PN) == ValueExprMap.end() && \"PHI node already processed?\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 3407, __PRETTY_FUNCTION__)) |
| 3407 | "PHI node already processed?")((ValueExprMap.find_as(PN) == ValueExprMap.end() && "PHI node already processed?" ) ? static_cast<void> (0) : __assert_fail ("ValueExprMap.find_as(PN) == ValueExprMap.end() && \"PHI node already processed?\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 3407, __PRETTY_FUNCTION__)); |
| 3408 | ValueExprMap.insert(std::make_pair(SCEVCallbackVH(PN, this), SymbolicName)); |
| 3409 | |
| 3410 | // Using this symbolic name for the PHI, analyze the value coming around |
| 3411 | // the back-edge. |
| 3412 | const SCEV *BEValue = getSCEV(BEValueV); |
| 3413 | |
| 3414 | // NOTE: If BEValue is loop invariant, we know that the PHI node just |
| 3415 | // has a special value for the first iteration of the loop. |
| 3416 | |
| 3417 | // If the value coming around the backedge is an add with the symbolic |
| 3418 | // value we just inserted, then we found a simple induction variable! |
| 3419 | if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(BEValue)) { |
| 3420 | // If there is a single occurrence of the symbolic value, replace it |
| 3421 | // with a recurrence. |
| 3422 | unsigned FoundIndex = Add->getNumOperands(); |
| 3423 | for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i) |
| 3424 | if (Add->getOperand(i) == SymbolicName) |
| 3425 | if (FoundIndex == e) { |
| 3426 | FoundIndex = i; |
| 3427 | break; |
| 3428 | } |
| 3429 | |
| 3430 | if (FoundIndex != Add->getNumOperands()) { |
| 3431 | // Create an add with everything but the specified operand. |
| 3432 | SmallVector<const SCEV *, 8> Ops; |
| 3433 | for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i) |
| 3434 | if (i != FoundIndex) |
| 3435 | Ops.push_back(Add->getOperand(i)); |
| 3436 | const SCEV *Accum = getAddExpr(Ops); |
| 3437 | |
| 3438 | // This is not a valid addrec if the step amount is varying each |
| 3439 | // loop iteration, but is not itself an addrec in this loop. |
| 3440 | if (isLoopInvariant(Accum, L) || |
| 3441 | (isa<SCEVAddRecExpr>(Accum) && |
| 3442 | cast<SCEVAddRecExpr>(Accum)->getLoop() == L)) { |
| 3443 | SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap; |
| 3444 | |
| 3445 | // If the increment doesn't overflow, then neither the addrec nor |
| 3446 | // the post-increment will overflow. |
| 3447 | if (const AddOperator *OBO = dyn_cast<AddOperator>(BEValueV)) { |
| 3448 | if (OBO->hasNoUnsignedWrap()) |
| 3449 | Flags = setFlags(Flags, SCEV::FlagNUW); |
| 3450 | if (OBO->hasNoSignedWrap()) |
| 3451 | Flags = setFlags(Flags, SCEV::FlagNSW); |
| 3452 | } else if (GEPOperator *GEP = dyn_cast<GEPOperator>(BEValueV)) { |
| 3453 | // If the increment is an inbounds GEP, then we know the address |
| 3454 | // space cannot be wrapped around. We cannot make any guarantee |
| 3455 | // about signed or unsigned overflow because pointers are |
| 3456 | // unsigned but we may have a negative index from the base |
| 3457 | // pointer. We can guarantee that no unsigned wrap occurs if the |
| 3458 | // indices form a positive value. |
| 3459 | if (GEP->isInBounds()) { |
| 3460 | Flags = setFlags(Flags, SCEV::FlagNW); |
| 3461 | |
| 3462 | const SCEV *Ptr = getSCEV(GEP->getPointerOperand()); |
| 3463 | if (isKnownPositive(getMinusSCEV(getSCEV(GEP), Ptr))) |
| 3464 | Flags = setFlags(Flags, SCEV::FlagNUW); |
| 3465 | } |
| 3466 | } else if (const SubOperator *OBO = |
| 3467 | dyn_cast<SubOperator>(BEValueV)) { |
| 3468 | if (OBO->hasNoUnsignedWrap()) |
| 3469 | Flags = setFlags(Flags, SCEV::FlagNUW); |
| 3470 | if (OBO->hasNoSignedWrap()) |
| 3471 | Flags = setFlags(Flags, SCEV::FlagNSW); |
| 3472 | } |
| 3473 | |
| 3474 | const SCEV *StartVal = getSCEV(StartValueV); |
| 3475 | const SCEV *PHISCEV = getAddRecExpr(StartVal, Accum, L, Flags); |
| 3476 | |
| 3477 | // Since the no-wrap flags are on the increment, they apply to the |
| 3478 | // post-incremented value as well. |
| 3479 | if (isLoopInvariant(Accum, L)) |
| 3480 | (void)getAddRecExpr(getAddExpr(StartVal, Accum), |
| 3481 | Accum, L, Flags); |
| 3482 | |
| 3483 | // Okay, for the entire analysis of this edge we assumed the PHI |
| 3484 | // to be symbolic. We now need to go back and purge all of the |
| 3485 | // entries for the scalars that use the symbolic expression. |
| 3486 | ForgetSymbolicName(PN, SymbolicName); |
| 3487 | ValueExprMap[SCEVCallbackVH(PN, this)] = PHISCEV; |
| 3488 | return PHISCEV; |
| 3489 | } |
| 3490 | } |
| 3491 | } else if (const SCEVAddRecExpr *AddRec = |
| 3492 | dyn_cast<SCEVAddRecExpr>(BEValue)) { |
| 3493 | // Otherwise, this could be a loop like this: |
| 3494 | // i = 0; for (j = 1; ..; ++j) { .... i = j; } |
| 3495 | // In this case, j = {1,+,1} and BEValue is j. |
| 3496 | // Because the other in-value of i (0) fits the evolution of BEValue |
| 3497 | // i really is an addrec evolution. |
| 3498 | if (AddRec->getLoop() == L && AddRec->isAffine()) { |
| 3499 | const SCEV *StartVal = getSCEV(StartValueV); |
| 3500 | |
| 3501 | // If StartVal = j.start - j.stride, we can use StartVal as the |
| 3502 | // initial step of the addrec evolution. |
| 3503 | if (StartVal == getMinusSCEV(AddRec->getOperand(0), |
| 3504 | AddRec->getOperand(1))) { |
| 3505 | // FIXME: For constant StartVal, we should be able to infer |
| 3506 | // no-wrap flags. |
| 3507 | const SCEV *PHISCEV = |
| 3508 | getAddRecExpr(StartVal, AddRec->getOperand(1), L, |
| 3509 | SCEV::FlagAnyWrap); |
| 3510 | |
| 3511 | // Okay, for the entire analysis of this edge we assumed the PHI |
| 3512 | // to be symbolic. We now need to go back and purge all of the |
| 3513 | // entries for the scalars that use the symbolic expression. |
| 3514 | ForgetSymbolicName(PN, SymbolicName); |
| 3515 | ValueExprMap[SCEVCallbackVH(PN, this)] = PHISCEV; |
| 3516 | return PHISCEV; |
| 3517 | } |
| 3518 | } |
| 3519 | } |
| 3520 | } |
| 3521 | } |
| 3522 | |
| 3523 | // If the PHI has a single incoming value, follow that value, unless the |
| 3524 | // PHI's incoming blocks are in a different loop, in which case doing so |
| 3525 | // risks breaking LCSSA form. Instcombine would normally zap these, but |
| 3526 | // it doesn't have DominatorTree information, so it may miss cases. |
| 3527 | if (Value *V = SimplifyInstruction(PN, DL, TLI, DT, AT)) |
| 3528 | if (LI->replacementPreservesLCSSAForm(PN, V)) |
| 3529 | return getSCEV(V); |
| 3530 | |
| 3531 | // If it's not a loop phi, we can't handle it yet. |
| 3532 | return getUnknown(PN); |
| 3533 | } |
| 3534 | |
| 3535 | /// createNodeForGEP - Expand GEP instructions into add and multiply |
| 3536 | /// operations. This allows them to be analyzed by regular SCEV code. |
| 3537 | /// |
| 3538 | const SCEV *ScalarEvolution::createNodeForGEP(GEPOperator *GEP) { |
| 3539 | Type *IntPtrTy = getEffectiveSCEVType(GEP->getType()); |
| 3540 | Value *Base = GEP->getOperand(0); |
| 3541 | // Don't attempt to analyze GEPs over unsized objects. |
| 3542 | if (!Base->getType()->getPointerElementType()->isSized()) |
| 3543 | return getUnknown(GEP); |
| 3544 | |
| 3545 | // Don't blindly transfer the inbounds flag from the GEP instruction to the |
| 3546 | // Add expression, because the Instruction may be guarded by control flow |
| 3547 | // and the no-overflow bits may not be valid for the expression in any |
| 3548 | // context. |
| 3549 | SCEV::NoWrapFlags Wrap = GEP->isInBounds() ? SCEV::FlagNSW : SCEV::FlagAnyWrap; |
| 3550 | |
| 3551 | const SCEV *TotalOffset = getConstant(IntPtrTy, 0); |
| 3552 | gep_type_iterator GTI = gep_type_begin(GEP); |
| 3553 | for (GetElementPtrInst::op_iterator I = std::next(GEP->op_begin()), |
| 3554 | E = GEP->op_end(); |
| 3555 | I != E; ++I) { |
| 3556 | Value *Index = *I; |
| 3557 | // Compute the (potentially symbolic) offset in bytes for this index. |
| 3558 | if (StructType *STy = dyn_cast<StructType>(*GTI++)) { |
| 3559 | // For a struct, add the member offset. |
| 3560 | unsigned FieldNo = cast<ConstantInt>(Index)->getZExtValue(); |
| 3561 | const SCEV *FieldOffset = getOffsetOfExpr(IntPtrTy, STy, FieldNo); |
| 3562 | |
| 3563 | // Add the field offset to the running total offset. |
| 3564 | TotalOffset = getAddExpr(TotalOffset, FieldOffset); |
| 3565 | } else { |
| 3566 | // For an array, add the element offset, explicitly scaled. |
| 3567 | const SCEV *ElementSize = getSizeOfExpr(IntPtrTy, *GTI); |
| 3568 | const SCEV *IndexS = getSCEV(Index); |
| 3569 | // Getelementptr indices are signed. |
| 3570 | IndexS = getTruncateOrSignExtend(IndexS, IntPtrTy); |
| 3571 | |
| 3572 | // Multiply the index by the element size to compute the element offset. |
| 3573 | const SCEV *LocalOffset = getMulExpr(IndexS, ElementSize, Wrap); |
| 3574 | |
| 3575 | // Add the element offset to the running total offset. |
| 3576 | TotalOffset = getAddExpr(TotalOffset, LocalOffset); |
| 3577 | } |
| 3578 | } |
| 3579 | |
| 3580 | // Get the SCEV for the GEP base. |
| 3581 | const SCEV *BaseS = getSCEV(Base); |
| 3582 | |
| 3583 | // Add the total offset from all the GEP indices to the base. |
| 3584 | return getAddExpr(BaseS, TotalOffset, Wrap); |
| 3585 | } |
| 3586 | |
| 3587 | /// GetMinTrailingZeros - Determine the minimum number of zero bits that S is |
| 3588 | /// guaranteed to end in (at every loop iteration). It is, at the same time, |
| 3589 | /// the minimum number of times S is divisible by 2. For example, given {4,+,8} |
| 3590 | /// it returns 2. If S is guaranteed to be 0, it returns the bitwidth of S. |
| 3591 | uint32_t |
| 3592 | ScalarEvolution::GetMinTrailingZeros(const SCEV *S) { |
| 3593 | if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S)) |
| 3594 | return C->getValue()->getValue().countTrailingZeros(); |
| 3595 | |
| 3596 | if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(S)) |
| 3597 | return std::min(GetMinTrailingZeros(T->getOperand()), |
| 3598 | (uint32_t)getTypeSizeInBits(T->getType())); |
| 3599 | |
| 3600 | if (const SCEVZeroExtendExpr *E = dyn_cast<SCEVZeroExtendExpr>(S)) { |
| 3601 | uint32_t OpRes = GetMinTrailingZeros(E->getOperand()); |
| 3602 | return OpRes == getTypeSizeInBits(E->getOperand()->getType()) ? |
| 3603 | getTypeSizeInBits(E->getType()) : OpRes; |
| 3604 | } |
| 3605 | |
| 3606 | if (const SCEVSignExtendExpr *E = dyn_cast<SCEVSignExtendExpr>(S)) { |
| 3607 | uint32_t OpRes = GetMinTrailingZeros(E->getOperand()); |
| 3608 | return OpRes == getTypeSizeInBits(E->getOperand()->getType()) ? |
| 3609 | getTypeSizeInBits(E->getType()) : OpRes; |
| 3610 | } |
| 3611 | |
| 3612 | if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(S)) { |
| 3613 | // The result is the min of all operands results. |
| 3614 | uint32_t MinOpRes = GetMinTrailingZeros(A->getOperand(0)); |
| 3615 | for (unsigned i = 1, e = A->getNumOperands(); MinOpRes && i != e; ++i) |
| 3616 | MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(A->getOperand(i))); |
| 3617 | return MinOpRes; |
| 3618 | } |
| 3619 | |
| 3620 | if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(S)) { |
| 3621 | // The result is the sum of all operands results. |
| 3622 | uint32_t SumOpRes = GetMinTrailingZeros(M->getOperand(0)); |
| 3623 | uint32_t BitWidth = getTypeSizeInBits(M->getType()); |
| 3624 | for (unsigned i = 1, e = M->getNumOperands(); |
| 3625 | SumOpRes != BitWidth && i != e; ++i) |
| 3626 | SumOpRes = std::min(SumOpRes + GetMinTrailingZeros(M->getOperand(i)), |
| 3627 | BitWidth); |
| 3628 | return SumOpRes; |
| 3629 | } |
| 3630 | |
| 3631 | if (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(S)) { |
| 3632 | // The result is the min of all operands results. |
| 3633 | uint32_t MinOpRes = GetMinTrailingZeros(A->getOperand(0)); |
| 3634 | for (unsigned i = 1, e = A->getNumOperands(); MinOpRes && i != e; ++i) |
| 3635 | MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(A->getOperand(i))); |
| 3636 | return MinOpRes; |
| 3637 | } |
| 3638 | |
| 3639 | if (const SCEVSMaxExpr *M = dyn_cast<SCEVSMaxExpr>(S)) { |
| 3640 | // The result is the min of all operands results. |
| 3641 | uint32_t MinOpRes = GetMinTrailingZeros(M->getOperand(0)); |
| 3642 | for (unsigned i = 1, e = M->getNumOperands(); MinOpRes && i != e; ++i) |
| 3643 | MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(M->getOperand(i))); |
| 3644 | return MinOpRes; |
| 3645 | } |
| 3646 | |
| 3647 | if (const SCEVUMaxExpr *M = dyn_cast<SCEVUMaxExpr>(S)) { |
| 3648 | // The result is the min of all operands results. |
| 3649 | uint32_t MinOpRes = GetMinTrailingZeros(M->getOperand(0)); |
| 3650 | for (unsigned i = 1, e = M->getNumOperands(); MinOpRes && i != e; ++i) |
| 3651 | MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(M->getOperand(i))); |
| 3652 | return MinOpRes; |
| 3653 | } |
| 3654 | |
| 3655 | if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) { |
| 3656 | // For a SCEVUnknown, ask ValueTracking. |
| 3657 | unsigned BitWidth = getTypeSizeInBits(U->getType()); |
| 3658 | APInt Zeros(BitWidth, 0), Ones(BitWidth, 0); |
| 3659 | computeKnownBits(U->getValue(), Zeros, Ones, DL, 0, AT, nullptr, DT); |
| 3660 | return Zeros.countTrailingOnes(); |
| 3661 | } |
| 3662 | |
| 3663 | // SCEVUDivExpr |
| 3664 | return 0; |
| 3665 | } |
| 3666 | |
| 3667 | /// GetRangeFromMetadata - Helper method to assign a range to V from |
| 3668 | /// metadata present in the IR. |
| 3669 | static Optional<ConstantRange> GetRangeFromMetadata(Value *V) { |
| 3670 | if (Instruction *I = dyn_cast<Instruction>(V)) { |
| 3671 | if (MDNode *MD = I->getMetadata(LLVMContext::MD_range)) { |
| 3672 | ConstantRange TotalRange( |
| 3673 | cast<IntegerType>(I->getType())->getBitWidth(), false); |
| 3674 | |
| 3675 | unsigned NumRanges = MD->getNumOperands() / 2; |
| 3676 | assert(NumRanges >= 1)((NumRanges >= 1) ? static_cast<void> (0) : __assert_fail ("NumRanges >= 1", "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 3676, __PRETTY_FUNCTION__)); |
| 3677 | |
| 3678 | for (unsigned i = 0; i < NumRanges; ++i) { |
| 3679 | ConstantInt *Lower = cast<ConstantInt>(MD->getOperand(2*i + 0)); |
| 3680 | ConstantInt *Upper = cast<ConstantInt>(MD->getOperand(2*i + 1)); |
| 3681 | ConstantRange Range(Lower->getValue(), Upper->getValue()); |
| 3682 | TotalRange = TotalRange.unionWith(Range); |
| 3683 | } |
| 3684 | |
| 3685 | return TotalRange; |
| 3686 | } |
| 3687 | } |
| 3688 | |
| 3689 | return None; |
| 3690 | } |
| 3691 | |
| 3692 | /// getUnsignedRange - Determine the unsigned range for a particular SCEV. |
| 3693 | /// |
| 3694 | ConstantRange |
| 3695 | ScalarEvolution::getUnsignedRange(const SCEV *S) { |
| 3696 | // See if we've computed this range already. |
| 3697 | DenseMap<const SCEV *, ConstantRange>::iterator I = UnsignedRanges.find(S); |
| 3698 | if (I != UnsignedRanges.end()) |
| 3699 | return I->second; |
| 3700 | |
| 3701 | if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S)) |
| 3702 | return setUnsignedRange(C, ConstantRange(C->getValue()->getValue())); |
| 3703 | |
| 3704 | unsigned BitWidth = getTypeSizeInBits(S->getType()); |
| 3705 | ConstantRange ConservativeResult(BitWidth, /*isFullSet=*/true); |
| 3706 | |
| 3707 | // If the value has known zeros, the maximum unsigned value will have those |
| 3708 | // known zeros as well. |
| 3709 | uint32_t TZ = GetMinTrailingZeros(S); |
| 3710 | if (TZ != 0) |
| 3711 | ConservativeResult = |
| 3712 | ConstantRange(APInt::getMinValue(BitWidth), |
| 3713 | APInt::getMaxValue(BitWidth).lshr(TZ).shl(TZ) + 1); |
| 3714 | |
| 3715 | if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) { |
| 3716 | ConstantRange X = getUnsignedRange(Add->getOperand(0)); |
| 3717 | for (unsigned i = 1, e = Add->getNumOperands(); i != e; ++i) |
| 3718 | X = X.add(getUnsignedRange(Add->getOperand(i))); |
| 3719 | return setUnsignedRange(Add, ConservativeResult.intersectWith(X)); |
| 3720 | } |
| 3721 | |
| 3722 | if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(S)) { |
| 3723 | ConstantRange X = getUnsignedRange(Mul->getOperand(0)); |
| 3724 | for (unsigned i = 1, e = Mul->getNumOperands(); i != e; ++i) |
| 3725 | X = X.multiply(getUnsignedRange(Mul->getOperand(i))); |
| 3726 | return setUnsignedRange(Mul, ConservativeResult.intersectWith(X)); |
| 3727 | } |
| 3728 | |
| 3729 | if (const SCEVSMaxExpr *SMax = dyn_cast<SCEVSMaxExpr>(S)) { |
| 3730 | ConstantRange X = getUnsignedRange(SMax->getOperand(0)); |
| 3731 | for (unsigned i = 1, e = SMax->getNumOperands(); i != e; ++i) |
| 3732 | X = X.smax(getUnsignedRange(SMax->getOperand(i))); |
| 3733 | return setUnsignedRange(SMax, ConservativeResult.intersectWith(X)); |
| 3734 | } |
| 3735 | |
| 3736 | if (const SCEVUMaxExpr *UMax = dyn_cast<SCEVUMaxExpr>(S)) { |
| 3737 | ConstantRange X = getUnsignedRange(UMax->getOperand(0)); |
| 3738 | for (unsigned i = 1, e = UMax->getNumOperands(); i != e; ++i) |
| 3739 | X = X.umax(getUnsignedRange(UMax->getOperand(i))); |
| 3740 | return setUnsignedRange(UMax, ConservativeResult.intersectWith(X)); |
| 3741 | } |
| 3742 | |
| 3743 | if (const SCEVUDivExpr *UDiv = dyn_cast<SCEVUDivExpr>(S)) { |
| 3744 | ConstantRange X = getUnsignedRange(UDiv->getLHS()); |
| 3745 | ConstantRange Y = getUnsignedRange(UDiv->getRHS()); |
| 3746 | return setUnsignedRange(UDiv, ConservativeResult.intersectWith(X.udiv(Y))); |
| 3747 | } |
| 3748 | |
| 3749 | if (const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(S)) { |
| 3750 | ConstantRange X = getUnsignedRange(ZExt->getOperand()); |
| 3751 | return setUnsignedRange(ZExt, |
| 3752 | ConservativeResult.intersectWith(X.zeroExtend(BitWidth))); |
| 3753 | } |
| 3754 | |
| 3755 | if (const SCEVSignExtendExpr *SExt = dyn_cast<SCEVSignExtendExpr>(S)) { |
| 3756 | ConstantRange X = getUnsignedRange(SExt->getOperand()); |
| 3757 | return setUnsignedRange(SExt, |
| 3758 | ConservativeResult.intersectWith(X.signExtend(BitWidth))); |
| 3759 | } |
| 3760 | |
| 3761 | if (const SCEVTruncateExpr *Trunc = dyn_cast<SCEVTruncateExpr>(S)) { |
| 3762 | ConstantRange X = getUnsignedRange(Trunc->getOperand()); |
| 3763 | return setUnsignedRange(Trunc, |
| 3764 | ConservativeResult.intersectWith(X.truncate(BitWidth))); |
| 3765 | } |
| 3766 | |
| 3767 | if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(S)) { |
| 3768 | // If there's no unsigned wrap, the value will never be less than its |
| 3769 | // initial value. |
| 3770 | if (AddRec->getNoWrapFlags(SCEV::FlagNUW)) |
| 3771 | if (const SCEVConstant *C = dyn_cast<SCEVConstant>(AddRec->getStart())) |
| 3772 | if (!C->getValue()->isZero()) |
| 3773 | ConservativeResult = |
| 3774 | ConservativeResult.intersectWith( |
| 3775 | ConstantRange(C->getValue()->getValue(), APInt(BitWidth, 0))); |
| 3776 | |
| 3777 | // TODO: non-affine addrec |
| 3778 | if (AddRec->isAffine()) { |
| 3779 | Type *Ty = AddRec->getType(); |
| 3780 | const SCEV *MaxBECount = getMaxBackedgeTakenCount(AddRec->getLoop()); |
| 3781 | if (!isa<SCEVCouldNotCompute>(MaxBECount) && |
| 3782 | getTypeSizeInBits(MaxBECount->getType()) <= BitWidth) { |
| 3783 | MaxBECount = getNoopOrZeroExtend(MaxBECount, Ty); |
| 3784 | |
| 3785 | const SCEV *Start = AddRec->getStart(); |
| 3786 | const SCEV *Step = AddRec->getStepRecurrence(*this); |
| 3787 | |
| 3788 | ConstantRange StartRange = getUnsignedRange(Start); |
| 3789 | ConstantRange StepRange = getSignedRange(Step); |
| 3790 | ConstantRange MaxBECountRange = getUnsignedRange(MaxBECount); |
| 3791 | ConstantRange EndRange = |
| 3792 | StartRange.add(MaxBECountRange.multiply(StepRange)); |
| 3793 | |
| 3794 | // Check for overflow. This must be done with ConstantRange arithmetic |
| 3795 | // because we could be called from within the ScalarEvolution overflow |
| 3796 | // checking code. |
| 3797 | ConstantRange ExtStartRange = StartRange.zextOrTrunc(BitWidth*2+1); |
| 3798 | ConstantRange ExtStepRange = StepRange.sextOrTrunc(BitWidth*2+1); |
| 3799 | ConstantRange ExtMaxBECountRange = |
| 3800 | MaxBECountRange.zextOrTrunc(BitWidth*2+1); |
| 3801 | ConstantRange ExtEndRange = EndRange.zextOrTrunc(BitWidth*2+1); |
| 3802 | if (ExtStartRange.add(ExtMaxBECountRange.multiply(ExtStepRange)) != |
| 3803 | ExtEndRange) |
| 3804 | return setUnsignedRange(AddRec, ConservativeResult); |
| 3805 | |
| 3806 | APInt Min = APIntOps::umin(StartRange.getUnsignedMin(), |
| 3807 | EndRange.getUnsignedMin()); |
| 3808 | APInt Max = APIntOps::umax(StartRange.getUnsignedMax(), |
| 3809 | EndRange.getUnsignedMax()); |
| 3810 | if (Min.isMinValue() && Max.isMaxValue()) |
| 3811 | return setUnsignedRange(AddRec, ConservativeResult); |
| 3812 | return setUnsignedRange(AddRec, |
| 3813 | ConservativeResult.intersectWith(ConstantRange(Min, Max+1))); |
| 3814 | } |
| 3815 | } |
| 3816 | |
| 3817 | return setUnsignedRange(AddRec, ConservativeResult); |
| 3818 | } |
| 3819 | |
| 3820 | if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) { |
| 3821 | // Check if the IR explicitly contains !range metadata. |
| 3822 | Optional<ConstantRange> MDRange = GetRangeFromMetadata(U->getValue()); |
| 3823 | if (MDRange.hasValue()) |
| 3824 | ConservativeResult = ConservativeResult.intersectWith(MDRange.getValue()); |
| 3825 | |
| 3826 | // For a SCEVUnknown, ask ValueTracking. |
| 3827 | APInt Zeros(BitWidth, 0), Ones(BitWidth, 0); |
| 3828 | computeKnownBits(U->getValue(), Zeros, Ones, DL, 0, AT, nullptr, DT); |
| 3829 | if (Ones == ~Zeros + 1) |
| 3830 | return setUnsignedRange(U, ConservativeResult); |
| 3831 | return setUnsignedRange(U, |
| 3832 | ConservativeResult.intersectWith(ConstantRange(Ones, ~Zeros + 1))); |
| 3833 | } |
| 3834 | |
| 3835 | return setUnsignedRange(S, ConservativeResult); |
| 3836 | } |
| 3837 | |
| 3838 | /// getSignedRange - Determine the signed range for a particular SCEV. |
| 3839 | /// |
| 3840 | ConstantRange |
| 3841 | ScalarEvolution::getSignedRange(const SCEV *S) { |
| 3842 | // See if we've computed this range already. |
| 3843 | DenseMap<const SCEV *, ConstantRange>::iterator I = SignedRanges.find(S); |
| 3844 | if (I != SignedRanges.end()) |
| 3845 | return I->second; |
| 3846 | |
| 3847 | if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S)) |
| 3848 | return setSignedRange(C, ConstantRange(C->getValue()->getValue())); |
| 3849 | |
| 3850 | unsigned BitWidth = getTypeSizeInBits(S->getType()); |
| 3851 | ConstantRange ConservativeResult(BitWidth, /*isFullSet=*/true); |
| 3852 | |
| 3853 | // If the value has known zeros, the maximum signed value will have those |
| 3854 | // known zeros as well. |
| 3855 | uint32_t TZ = GetMinTrailingZeros(S); |
| 3856 | if (TZ != 0) |
| 3857 | ConservativeResult = |
| 3858 | ConstantRange(APInt::getSignedMinValue(BitWidth), |
| 3859 | APInt::getSignedMaxValue(BitWidth).ashr(TZ).shl(TZ) + 1); |
| 3860 | |
| 3861 | if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) { |
| 3862 | ConstantRange X = getSignedRange(Add->getOperand(0)); |
| 3863 | for (unsigned i = 1, e = Add->getNumOperands(); i != e; ++i) |
| 3864 | X = X.add(getSignedRange(Add->getOperand(i))); |
| 3865 | return setSignedRange(Add, ConservativeResult.intersectWith(X)); |
| 3866 | } |
| 3867 | |
| 3868 | if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(S)) { |
| 3869 | ConstantRange X = getSignedRange(Mul->getOperand(0)); |
| 3870 | for (unsigned i = 1, e = Mul->getNumOperands(); i != e; ++i) |
| 3871 | X = X.multiply(getSignedRange(Mul->getOperand(i))); |
| 3872 | return setSignedRange(Mul, ConservativeResult.intersectWith(X)); |
| 3873 | } |
| 3874 | |
| 3875 | if (const SCEVSMaxExpr *SMax = dyn_cast<SCEVSMaxExpr>(S)) { |
| 3876 | ConstantRange X = getSignedRange(SMax->getOperand(0)); |
| 3877 | for (unsigned i = 1, e = SMax->getNumOperands(); i != e; ++i) |
| 3878 | X = X.smax(getSignedRange(SMax->getOperand(i))); |
| 3879 | return setSignedRange(SMax, ConservativeResult.intersectWith(X)); |
| 3880 | } |
| 3881 | |
| 3882 | if (const SCEVUMaxExpr *UMax = dyn_cast<SCEVUMaxExpr>(S)) { |
| 3883 | ConstantRange X = getSignedRange(UMax->getOperand(0)); |
| 3884 | for (unsigned i = 1, e = UMax->getNumOperands(); i != e; ++i) |
| 3885 | X = X.umax(getSignedRange(UMax->getOperand(i))); |
| 3886 | return setSignedRange(UMax, ConservativeResult.intersectWith(X)); |
| 3887 | } |
| 3888 | |
| 3889 | if (const SCEVUDivExpr *UDiv = dyn_cast<SCEVUDivExpr>(S)) { |
| 3890 | ConstantRange X = getSignedRange(UDiv->getLHS()); |
| 3891 | ConstantRange Y = getSignedRange(UDiv->getRHS()); |
| 3892 | return setSignedRange(UDiv, ConservativeResult.intersectWith(X.udiv(Y))); |
| 3893 | } |
| 3894 | |
| 3895 | if (const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(S)) { |
| 3896 | ConstantRange X = getSignedRange(ZExt->getOperand()); |
| 3897 | return setSignedRange(ZExt, |
| 3898 | ConservativeResult.intersectWith(X.zeroExtend(BitWidth))); |
| 3899 | } |
| 3900 | |
| 3901 | if (const SCEVSignExtendExpr *SExt = dyn_cast<SCEVSignExtendExpr>(S)) { |
| 3902 | ConstantRange X = getSignedRange(SExt->getOperand()); |
| 3903 | return setSignedRange(SExt, |
| 3904 | ConservativeResult.intersectWith(X.signExtend(BitWidth))); |
| 3905 | } |
| 3906 | |
| 3907 | if (const SCEVTruncateExpr *Trunc = dyn_cast<SCEVTruncateExpr>(S)) { |
| 3908 | ConstantRange X = getSignedRange(Trunc->getOperand()); |
| 3909 | return setSignedRange(Trunc, |
| 3910 | ConservativeResult.intersectWith(X.truncate(BitWidth))); |
| 3911 | } |
| 3912 | |
| 3913 | if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(S)) { |
| 3914 | // If there's no signed wrap, and all the operands have the same sign or |
| 3915 | // zero, the value won't ever change sign. |
| 3916 | if (AddRec->getNoWrapFlags(SCEV::FlagNSW)) { |
| 3917 | bool AllNonNeg = true; |
| 3918 | bool AllNonPos = true; |
| 3919 | for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i) { |
| 3920 | if (!isKnownNonNegative(AddRec->getOperand(i))) AllNonNeg = false; |
| 3921 | if (!isKnownNonPositive(AddRec->getOperand(i))) AllNonPos = false; |
| 3922 | } |
| 3923 | if (AllNonNeg) |
| 3924 | ConservativeResult = ConservativeResult.intersectWith( |
| 3925 | ConstantRange(APInt(BitWidth, 0), |
| 3926 | APInt::getSignedMinValue(BitWidth))); |
| 3927 | else if (AllNonPos) |
| 3928 | ConservativeResult = ConservativeResult.intersectWith( |
| 3929 | ConstantRange(APInt::getSignedMinValue(BitWidth), |
| 3930 | APInt(BitWidth, 1))); |
| 3931 | } |
| 3932 | |
| 3933 | // TODO: non-affine addrec |
| 3934 | if (AddRec->isAffine()) { |
| 3935 | Type *Ty = AddRec->getType(); |
| 3936 | const SCEV *MaxBECount = getMaxBackedgeTakenCount(AddRec->getLoop()); |
| 3937 | if (!isa<SCEVCouldNotCompute>(MaxBECount) && |
| 3938 | getTypeSizeInBits(MaxBECount->getType()) <= BitWidth) { |
| 3939 | MaxBECount = getNoopOrZeroExtend(MaxBECount, Ty); |
| 3940 | |
| 3941 | const SCEV *Start = AddRec->getStart(); |
| 3942 | const SCEV *Step = AddRec->getStepRecurrence(*this); |
| 3943 | |
| 3944 | ConstantRange StartRange = getSignedRange(Start); |
| 3945 | ConstantRange StepRange = getSignedRange(Step); |
| 3946 | ConstantRange MaxBECountRange = getUnsignedRange(MaxBECount); |
| 3947 | ConstantRange EndRange = |
| 3948 | StartRange.add(MaxBECountRange.multiply(StepRange)); |
| 3949 | |
| 3950 | // Check for overflow. This must be done with ConstantRange arithmetic |
| 3951 | // because we could be called from within the ScalarEvolution overflow |
| 3952 | // checking code. |
| 3953 | ConstantRange ExtStartRange = StartRange.sextOrTrunc(BitWidth*2+1); |
| 3954 | ConstantRange ExtStepRange = StepRange.sextOrTrunc(BitWidth*2+1); |
| 3955 | ConstantRange ExtMaxBECountRange = |
| 3956 | MaxBECountRange.zextOrTrunc(BitWidth*2+1); |
| 3957 | ConstantRange ExtEndRange = EndRange.sextOrTrunc(BitWidth*2+1); |
| 3958 | if (ExtStartRange.add(ExtMaxBECountRange.multiply(ExtStepRange)) != |
| 3959 | ExtEndRange) |
| 3960 | return setSignedRange(AddRec, ConservativeResult); |
| 3961 | |
| 3962 | APInt Min = APIntOps::smin(StartRange.getSignedMin(), |
| 3963 | EndRange.getSignedMin()); |
| 3964 | APInt Max = APIntOps::smax(StartRange.getSignedMax(), |
| 3965 | EndRange.getSignedMax()); |
| 3966 | if (Min.isMinSignedValue() && Max.isMaxSignedValue()) |
| 3967 | return setSignedRange(AddRec, ConservativeResult); |
| 3968 | return setSignedRange(AddRec, |
| 3969 | ConservativeResult.intersectWith(ConstantRange(Min, Max+1))); |
| 3970 | } |
| 3971 | } |
| 3972 | |
| 3973 | return setSignedRange(AddRec, ConservativeResult); |
| 3974 | } |
| 3975 | |
| 3976 | if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) { |
| 3977 | // Check if the IR explicitly contains !range metadata. |
| 3978 | Optional<ConstantRange> MDRange = GetRangeFromMetadata(U->getValue()); |
| 3979 | if (MDRange.hasValue()) |
| 3980 | ConservativeResult = ConservativeResult.intersectWith(MDRange.getValue()); |
| 3981 | |
| 3982 | // For a SCEVUnknown, ask ValueTracking. |
| 3983 | if (!U->getValue()->getType()->isIntegerTy() && !DL) |
| 3984 | return setSignedRange(U, ConservativeResult); |
| 3985 | unsigned NS = ComputeNumSignBits(U->getValue(), DL, 0, AT, nullptr, DT); |
| 3986 | if (NS <= 1) |
| 3987 | return setSignedRange(U, ConservativeResult); |
| 3988 | return setSignedRange(U, ConservativeResult.intersectWith( |
| 3989 | ConstantRange(APInt::getSignedMinValue(BitWidth).ashr(NS - 1), |
| 3990 | APInt::getSignedMaxValue(BitWidth).ashr(NS - 1)+1))); |
| 3991 | } |
| 3992 | |
| 3993 | return setSignedRange(S, ConservativeResult); |
| 3994 | } |
| 3995 | |
| 3996 | /// createSCEV - We know that there is no SCEV for the specified value. |
| 3997 | /// Analyze the expression. |
| 3998 | /// |
| 3999 | const SCEV *ScalarEvolution::createSCEV(Value *V) { |
| 4000 | if (!isSCEVable(V->getType())) |
| 4001 | return getUnknown(V); |
| 4002 | |
| 4003 | unsigned Opcode = Instruction::UserOp1; |
| 4004 | if (Instruction *I = dyn_cast<Instruction>(V)) { |
| 4005 | Opcode = I->getOpcode(); |
| 4006 | |
| 4007 | // Don't attempt to analyze instructions in blocks that aren't |
| 4008 | // reachable. Such instructions don't matter, and they aren't required |
| 4009 | // to obey basic rules for definitions dominating uses which this |
| 4010 | // analysis depends on. |
| 4011 | if (!DT->isReachableFromEntry(I->getParent())) |
| 4012 | return getUnknown(V); |
| 4013 | } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) |
| 4014 | Opcode = CE->getOpcode(); |
| 4015 | else if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) |
| 4016 | return getConstant(CI); |
| 4017 | else if (isa<ConstantPointerNull>(V)) |
| 4018 | return getConstant(V->getType(), 0); |
| 4019 | else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) |
| 4020 | return GA->mayBeOverridden() ? getUnknown(V) : getSCEV(GA->getAliasee()); |
| 4021 | else |
| 4022 | return getUnknown(V); |
| 4023 | |
| 4024 | Operator *U = cast<Operator>(V); |
| 4025 | switch (Opcode) { |
| 4026 | case Instruction::Add: { |
| 4027 | // The simple thing to do would be to just call getSCEV on both operands |
| 4028 | // and call getAddExpr with the result. However if we're looking at a |
| 4029 | // bunch of things all added together, this can be quite inefficient, |
| 4030 | // because it leads to N-1 getAddExpr calls for N ultimate operands. |
| 4031 | // Instead, gather up all the operands and make a single getAddExpr call. |
| 4032 | // LLVM IR canonical form means we need only traverse the left operands. |
| 4033 | // |
| 4034 | // Don't apply this instruction's NSW or NUW flags to the new |
| 4035 | // expression. The instruction may be guarded by control flow that the |
| 4036 | // no-wrap behavior depends on. Non-control-equivalent instructions can be |
| 4037 | // mapped to the same SCEV expression, and it would be incorrect to transfer |
| 4038 | // NSW/NUW semantics to those operations. |
| 4039 | SmallVector<const SCEV *, 4> AddOps; |
| 4040 | AddOps.push_back(getSCEV(U->getOperand(1))); |
| 4041 | for (Value *Op = U->getOperand(0); ; Op = U->getOperand(0)) { |
| 4042 | unsigned Opcode = Op->getValueID() - Value::InstructionVal; |
| 4043 | if (Opcode != Instruction::Add && Opcode != Instruction::Sub) |
| 4044 | break; |
| 4045 | U = cast<Operator>(Op); |
| 4046 | const SCEV *Op1 = getSCEV(U->getOperand(1)); |
| 4047 | if (Opcode == Instruction::Sub) |
| 4048 | AddOps.push_back(getNegativeSCEV(Op1)); |
| 4049 | else |
| 4050 | AddOps.push_back(Op1); |
| 4051 | } |
| 4052 | AddOps.push_back(getSCEV(U->getOperand(0))); |
| 4053 | return getAddExpr(AddOps); |
| 4054 | } |
| 4055 | case Instruction::Mul: { |
| 4056 | // Don't transfer NSW/NUW for the same reason as AddExpr. |
| 4057 | SmallVector<const SCEV *, 4> MulOps; |
| 4058 | MulOps.push_back(getSCEV(U->getOperand(1))); |
| 4059 | for (Value *Op = U->getOperand(0); |
| 4060 | Op->getValueID() == Instruction::Mul + Value::InstructionVal; |
| 4061 | Op = U->getOperand(0)) { |
| 4062 | U = cast<Operator>(Op); |
| 4063 | MulOps.push_back(getSCEV(U->getOperand(1))); |
| 4064 | } |
| 4065 | MulOps.push_back(getSCEV(U->getOperand(0))); |
| 4066 | return getMulExpr(MulOps); |
| 4067 | } |
| 4068 | case Instruction::UDiv: |
| 4069 | return getUDivExpr(getSCEV(U->getOperand(0)), |
| 4070 | getSCEV(U->getOperand(1))); |
| 4071 | case Instruction::Sub: |
| 4072 | return getMinusSCEV(getSCEV(U->getOperand(0)), |
| 4073 | getSCEV(U->getOperand(1))); |
| 4074 | case Instruction::And: |
| 4075 | // For an expression like x&255 that merely masks off the high bits, |
| 4076 | // use zext(trunc(x)) as the SCEV expression. |
| 4077 | if (ConstantInt *CI = dyn_cast<ConstantInt>(U->getOperand(1))) { |
| 4078 | if (CI->isNullValue()) |
| 4079 | return getSCEV(U->getOperand(1)); |
| 4080 | if (CI->isAllOnesValue()) |
| 4081 | return getSCEV(U->getOperand(0)); |
| 4082 | const APInt &A = CI->getValue(); |
| 4083 | |
| 4084 | // Instcombine's ShrinkDemandedConstant may strip bits out of |
| 4085 | // constants, obscuring what would otherwise be a low-bits mask. |
| 4086 | // Use computeKnownBits to compute what ShrinkDemandedConstant |
| 4087 | // knew about to reconstruct a low-bits mask value. |
| 4088 | unsigned LZ = A.countLeadingZeros(); |
| 4089 | unsigned TZ = A.countTrailingZeros(); |
| 4090 | unsigned BitWidth = A.getBitWidth(); |
| 4091 | APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0); |
| 4092 | computeKnownBits(U->getOperand(0), KnownZero, KnownOne, DL, |
| 4093 | 0, AT, nullptr, DT); |
| 4094 | |
| 4095 | APInt EffectiveMask = |
| 4096 | APInt::getLowBitsSet(BitWidth, BitWidth - LZ - TZ).shl(TZ); |
| 4097 | if ((LZ != 0 || TZ != 0) && !((~A & ~KnownZero) & EffectiveMask)) { |
| 4098 | const SCEV *MulCount = getConstant( |
| 4099 | ConstantInt::get(getContext(), APInt::getOneBitSet(BitWidth, TZ))); |
| 4100 | return getMulExpr( |
| 4101 | getZeroExtendExpr( |
| 4102 | getTruncateExpr( |
| 4103 | getUDivExactExpr(getSCEV(U->getOperand(0)), MulCount), |
| 4104 | IntegerType::get(getContext(), BitWidth - LZ - TZ)), |
| 4105 | U->getType()), |
| 4106 | MulCount); |
| 4107 | } |
| 4108 | } |
| 4109 | break; |
| 4110 | |
| 4111 | case Instruction::Or: |
| 4112 | // If the RHS of the Or is a constant, we may have something like: |
| 4113 | // X*4+1 which got turned into X*4|1. Handle this as an Add so loop |
| 4114 | // optimizations will transparently handle this case. |
| 4115 | // |
| 4116 | // In order for this transformation to be safe, the LHS must be of the |
| 4117 | // form X*(2^n) and the Or constant must be less than 2^n. |
| 4118 | if (ConstantInt *CI = dyn_cast<ConstantInt>(U->getOperand(1))) { |
| 4119 | const SCEV *LHS = getSCEV(U->getOperand(0)); |
| 4120 | const APInt &CIVal = CI->getValue(); |
| 4121 | if (GetMinTrailingZeros(LHS) >= |
| 4122 | (CIVal.getBitWidth() - CIVal.countLeadingZeros())) { |
| 4123 | // Build a plain add SCEV. |
| 4124 | const SCEV *S = getAddExpr(LHS, getSCEV(CI)); |
| 4125 | // If the LHS of the add was an addrec and it has no-wrap flags, |
| 4126 | // transfer the no-wrap flags, since an or won't introduce a wrap. |
| 4127 | if (const SCEVAddRecExpr *NewAR = dyn_cast<SCEVAddRecExpr>(S)) { |
| 4128 | const SCEVAddRecExpr *OldAR = cast<SCEVAddRecExpr>(LHS); |
| 4129 | const_cast<SCEVAddRecExpr *>(NewAR)->setNoWrapFlags( |
| 4130 | OldAR->getNoWrapFlags()); |
| 4131 | } |
| 4132 | return S; |
| 4133 | } |
| 4134 | } |
| 4135 | break; |
| 4136 | case Instruction::Xor: |
| 4137 | if (ConstantInt *CI = dyn_cast<ConstantInt>(U->getOperand(1))) { |
| 4138 | // If the RHS of the xor is a signbit, then this is just an add. |
| 4139 | // Instcombine turns add of signbit into xor as a strength reduction step. |
| 4140 | if (CI->getValue().isSignBit()) |
| 4141 | return getAddExpr(getSCEV(U->getOperand(0)), |
| 4142 | getSCEV(U->getOperand(1))); |
| 4143 | |
| 4144 | // If the RHS of xor is -1, then this is a not operation. |
| 4145 | if (CI->isAllOnesValue()) |
| 4146 | return getNotSCEV(getSCEV(U->getOperand(0))); |
| 4147 | |
| 4148 | // Model xor(and(x, C), C) as and(~x, C), if C is a low-bits mask. |
| 4149 | // This is a variant of the check for xor with -1, and it handles |
| 4150 | // the case where instcombine has trimmed non-demanded bits out |
| 4151 | // of an xor with -1. |
| 4152 | if (BinaryOperator *BO = dyn_cast<BinaryOperator>(U->getOperand(0))) |
| 4153 | if (ConstantInt *LCI = dyn_cast<ConstantInt>(BO->getOperand(1))) |
| 4154 | if (BO->getOpcode() == Instruction::And && |
| 4155 | LCI->getValue() == CI->getValue()) |
| 4156 | if (const SCEVZeroExtendExpr *Z = |
| 4157 | dyn_cast<SCEVZeroExtendExpr>(getSCEV(U->getOperand(0)))) { |
| 4158 | Type *UTy = U->getType(); |
| 4159 | const SCEV *Z0 = Z->getOperand(); |
| 4160 | Type *Z0Ty = Z0->getType(); |
| 4161 | unsigned Z0TySize = getTypeSizeInBits(Z0Ty); |
| 4162 | |
| 4163 | // If C is a low-bits mask, the zero extend is serving to |
| 4164 | // mask off the high bits. Complement the operand and |
| 4165 | // re-apply the zext. |
| 4166 | if (APIntOps::isMask(Z0TySize, CI->getValue())) |
| 4167 | return getZeroExtendExpr(getNotSCEV(Z0), UTy); |
| 4168 | |
| 4169 | // If C is a single bit, it may be in the sign-bit position |
| 4170 | // before the zero-extend. In this case, represent the xor |
| 4171 | // using an add, which is equivalent, and re-apply the zext. |
| 4172 | APInt Trunc = CI->getValue().trunc(Z0TySize); |
| 4173 | if (Trunc.zext(getTypeSizeInBits(UTy)) == CI->getValue() && |
| 4174 | Trunc.isSignBit()) |
| 4175 | return getZeroExtendExpr(getAddExpr(Z0, getConstant(Trunc)), |
| 4176 | UTy); |
| 4177 | } |
| 4178 | } |
| 4179 | break; |
| 4180 | |
| 4181 | case Instruction::Shl: |
| 4182 | // Turn shift left of a constant amount into a multiply. |
| 4183 | if (ConstantInt *SA = dyn_cast<ConstantInt>(U->getOperand(1))) { |
| 4184 | uint32_t BitWidth = cast<IntegerType>(U->getType())->getBitWidth(); |
| 4185 | |
| 4186 | // If the shift count is not less than the bitwidth, the result of |
| 4187 | // the shift is undefined. Don't try to analyze it, because the |
| 4188 | // resolution chosen here may differ from the resolution chosen in |
| 4189 | // other parts of the compiler. |
| 4190 | if (SA->getValue().uge(BitWidth)) |
| 4191 | break; |
| 4192 | |
| 4193 | Constant *X = ConstantInt::get(getContext(), |
| 4194 | APInt::getOneBitSet(BitWidth, SA->getZExtValue())); |
| 4195 | return getMulExpr(getSCEV(U->getOperand(0)), getSCEV(X)); |
| 4196 | } |
| 4197 | break; |
| 4198 | |
| 4199 | case Instruction::LShr: |
| 4200 | // Turn logical shift right of a constant into a unsigned divide. |
| 4201 | if (ConstantInt *SA = dyn_cast<ConstantInt>(U->getOperand(1))) { |
| 4202 | uint32_t BitWidth = cast<IntegerType>(U->getType())->getBitWidth(); |
| 4203 | |
| 4204 | // If the shift count is not less than the bitwidth, the result of |
| 4205 | // the shift is undefined. Don't try to analyze it, because the |
| 4206 | // resolution chosen here may differ from the resolution chosen in |
| 4207 | // other parts of the compiler. |
| 4208 | if (SA->getValue().uge(BitWidth)) |
| 4209 | break; |
| 4210 | |
| 4211 | Constant *X = ConstantInt::get(getContext(), |
| 4212 | APInt::getOneBitSet(BitWidth, SA->getZExtValue())); |
| 4213 | return getUDivExpr(getSCEV(U->getOperand(0)), getSCEV(X)); |
| 4214 | } |
| 4215 | break; |
| 4216 | |
| 4217 | case Instruction::AShr: |
| 4218 | // For a two-shift sext-inreg, use sext(trunc(x)) as the SCEV expression. |
| 4219 | if (ConstantInt *CI = dyn_cast<ConstantInt>(U->getOperand(1))) |
| 4220 | if (Operator *L = dyn_cast<Operator>(U->getOperand(0))) |
| 4221 | if (L->getOpcode() == Instruction::Shl && |
| 4222 | L->getOperand(1) == U->getOperand(1)) { |
| 4223 | uint64_t BitWidth = getTypeSizeInBits(U->getType()); |
| 4224 | |
| 4225 | // If the shift count is not less than the bitwidth, the result of |
| 4226 | // the shift is undefined. Don't try to analyze it, because the |
| 4227 | // resolution chosen here may differ from the resolution chosen in |
| 4228 | // other parts of the compiler. |
| 4229 | if (CI->getValue().uge(BitWidth)) |
| 4230 | break; |
| 4231 | |
| 4232 | uint64_t Amt = BitWidth - CI->getZExtValue(); |
| 4233 | if (Amt == BitWidth) |
| 4234 | return getSCEV(L->getOperand(0)); // shift by zero --> noop |
| 4235 | return |
| 4236 | getSignExtendExpr(getTruncateExpr(getSCEV(L->getOperand(0)), |
| 4237 | IntegerType::get(getContext(), |
| 4238 | Amt)), |
| 4239 | U->getType()); |
| 4240 | } |
| 4241 | break; |
| 4242 | |
| 4243 | case Instruction::Trunc: |
| 4244 | return getTruncateExpr(getSCEV(U->getOperand(0)), U->getType()); |
| 4245 | |
| 4246 | case Instruction::ZExt: |
| 4247 | return getZeroExtendExpr(getSCEV(U->getOperand(0)), U->getType()); |
| 4248 | |
| 4249 | case Instruction::SExt: |
| 4250 | return getSignExtendExpr(getSCEV(U->getOperand(0)), U->getType()); |
| 4251 | |
| 4252 | case Instruction::BitCast: |
| 4253 | // BitCasts are no-op casts so we just eliminate the cast. |
| 4254 | if (isSCEVable(U->getType()) && isSCEVable(U->getOperand(0)->getType())) |
| 4255 | return getSCEV(U->getOperand(0)); |
| 4256 | break; |
| 4257 | |
| 4258 | // It's tempting to handle inttoptr and ptrtoint as no-ops, however this can |
| 4259 | // lead to pointer expressions which cannot safely be expanded to GEPs, |
| 4260 | // because ScalarEvolution doesn't respect the GEP aliasing rules when |
| 4261 | // simplifying integer expressions. |
| 4262 | |
| 4263 | case Instruction::GetElementPtr: |
| 4264 | return createNodeForGEP(cast<GEPOperator>(U)); |
| 4265 | |
| 4266 | case Instruction::PHI: |
| 4267 | return createNodeForPHI(cast<PHINode>(U)); |
| 4268 | |
| 4269 | case Instruction::Select: |
| 4270 | // This could be a smax or umax that was lowered earlier. |
| 4271 | // Try to recover it. |
| 4272 | if (ICmpInst *ICI = dyn_cast<ICmpInst>(U->getOperand(0))) { |
| 4273 | Value *LHS = ICI->getOperand(0); |
| 4274 | Value *RHS = ICI->getOperand(1); |
| 4275 | switch (ICI->getPredicate()) { |
| 4276 | case ICmpInst::ICMP_SLT: |
| 4277 | case ICmpInst::ICMP_SLE: |
| 4278 | std::swap(LHS, RHS); |
| 4279 | // fall through |
| 4280 | case ICmpInst::ICMP_SGT: |
| 4281 | case ICmpInst::ICMP_SGE: |
| 4282 | // a >s b ? a+x : b+x -> smax(a, b)+x |
| 4283 | // a >s b ? b+x : a+x -> smin(a, b)+x |
| 4284 | if (LHS->getType() == U->getType()) { |
| 4285 | const SCEV *LS = getSCEV(LHS); |
| 4286 | const SCEV *RS = getSCEV(RHS); |
| 4287 | const SCEV *LA = getSCEV(U->getOperand(1)); |
| 4288 | const SCEV *RA = getSCEV(U->getOperand(2)); |
| 4289 | const SCEV *LDiff = getMinusSCEV(LA, LS); |
| 4290 | const SCEV *RDiff = getMinusSCEV(RA, RS); |
| 4291 | if (LDiff == RDiff) |
| 4292 | return getAddExpr(getSMaxExpr(LS, RS), LDiff); |
| 4293 | LDiff = getMinusSCEV(LA, RS); |
| 4294 | RDiff = getMinusSCEV(RA, LS); |
| 4295 | if (LDiff == RDiff) |
| 4296 | return getAddExpr(getSMinExpr(LS, RS), LDiff); |
| 4297 | } |
| 4298 | break; |
| 4299 | case ICmpInst::ICMP_ULT: |
| 4300 | case ICmpInst::ICMP_ULE: |
| 4301 | std::swap(LHS, RHS); |
| 4302 | // fall through |
| 4303 | case ICmpInst::ICMP_UGT: |
| 4304 | case ICmpInst::ICMP_UGE: |
| 4305 | // a >u b ? a+x : b+x -> umax(a, b)+x |
| 4306 | // a >u b ? b+x : a+x -> umin(a, b)+x |
| 4307 | if (LHS->getType() == U->getType()) { |
| 4308 | const SCEV *LS = getSCEV(LHS); |
| 4309 | const SCEV *RS = getSCEV(RHS); |
| 4310 | const SCEV *LA = getSCEV(U->getOperand(1)); |
| 4311 | const SCEV *RA = getSCEV(U->getOperand(2)); |
| 4312 | const SCEV *LDiff = getMinusSCEV(LA, LS); |
| 4313 | const SCEV *RDiff = getMinusSCEV(RA, RS); |
| 4314 | if (LDiff == RDiff) |
| 4315 | return getAddExpr(getUMaxExpr(LS, RS), LDiff); |
| 4316 | LDiff = getMinusSCEV(LA, RS); |
| 4317 | RDiff = getMinusSCEV(RA, LS); |
| 4318 | if (LDiff == RDiff) |
| 4319 | return getAddExpr(getUMinExpr(LS, RS), LDiff); |
| 4320 | } |
| 4321 | break; |
| 4322 | case ICmpInst::ICMP_NE: |
| 4323 | // n != 0 ? n+x : 1+x -> umax(n, 1)+x |
| 4324 | if (LHS->getType() == U->getType() && |
| 4325 | isa<ConstantInt>(RHS) && |
| 4326 | cast<ConstantInt>(RHS)->isZero()) { |
| 4327 | const SCEV *One = getConstant(LHS->getType(), 1); |
| 4328 | const SCEV *LS = getSCEV(LHS); |
| 4329 | const SCEV *LA = getSCEV(U->getOperand(1)); |
| 4330 | const SCEV *RA = getSCEV(U->getOperand(2)); |
| 4331 | const SCEV *LDiff = getMinusSCEV(LA, LS); |
| 4332 | const SCEV *RDiff = getMinusSCEV(RA, One); |
| 4333 | if (LDiff == RDiff) |
| 4334 | return getAddExpr(getUMaxExpr(One, LS), LDiff); |
| 4335 | } |
| 4336 | break; |
| 4337 | case ICmpInst::ICMP_EQ: |
| 4338 | // n == 0 ? 1+x : n+x -> umax(n, 1)+x |
| 4339 | if (LHS->getType() == U->getType() && |
| 4340 | isa<ConstantInt>(RHS) && |
| 4341 | cast<ConstantInt>(RHS)->isZero()) { |
| 4342 | const SCEV *One = getConstant(LHS->getType(), 1); |
| 4343 | const SCEV *LS = getSCEV(LHS); |
| 4344 | const SCEV *LA = getSCEV(U->getOperand(1)); |
| 4345 | const SCEV *RA = getSCEV(U->getOperand(2)); |
| 4346 | const SCEV *LDiff = getMinusSCEV(LA, One); |
| 4347 | const SCEV *RDiff = getMinusSCEV(RA, LS); |
| 4348 | if (LDiff == RDiff) |
| 4349 | return getAddExpr(getUMaxExpr(One, LS), LDiff); |
| 4350 | } |
| 4351 | break; |
| 4352 | default: |
| 4353 | break; |
| 4354 | } |
| 4355 | } |
| 4356 | |
| 4357 | default: // We cannot analyze this expression. |
| 4358 | break; |
| 4359 | } |
| 4360 | |
| 4361 | return getUnknown(V); |
| 4362 | } |
| 4363 | |
| 4364 | |
| 4365 | |
| 4366 | //===----------------------------------------------------------------------===// |
| 4367 | // Iteration Count Computation Code |
| 4368 | // |
| 4369 | |
| 4370 | unsigned ScalarEvolution::getSmallConstantTripCount(Loop *L) { |
| 4371 | if (BasicBlock *ExitingBB = L->getExitingBlock()) |
| 4372 | return getSmallConstantTripCount(L, ExitingBB); |
| 4373 | |
| 4374 | // No trip count information for multiple exits. |
| 4375 | return 0; |
| 4376 | } |
| 4377 | |
| 4378 | /// getSmallConstantTripCount - Returns the maximum trip count of this loop as a |
| 4379 | /// normal unsigned value. Returns 0 if the trip count is unknown or not |
| 4380 | /// constant. Will also return 0 if the maximum trip count is very large (>= |
| 4381 | /// 2^32). |
| 4382 | /// |
| 4383 | /// This "trip count" assumes that control exits via ExitingBlock. More |
| 4384 | /// precisely, it is the number of times that control may reach ExitingBlock |
| 4385 | /// before taking the branch. For loops with multiple exits, it may not be the |
| 4386 | /// number times that the loop header executes because the loop may exit |
| 4387 | /// prematurely via another branch. |
| 4388 | unsigned ScalarEvolution::getSmallConstantTripCount(Loop *L, |
| 4389 | BasicBlock *ExitingBlock) { |
| 4390 | assert(ExitingBlock && "Must pass a non-null exiting block!")((ExitingBlock && "Must pass a non-null exiting block!" ) ? static_cast<void> (0) : __assert_fail ("ExitingBlock && \"Must pass a non-null exiting block!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 4390, __PRETTY_FUNCTION__)); |
| 4391 | assert(L->isLoopExiting(ExitingBlock) &&((L->isLoopExiting(ExitingBlock) && "Exiting block must actually branch out of the loop!" ) ? static_cast<void> (0) : __assert_fail ("L->isLoopExiting(ExitingBlock) && \"Exiting block must actually branch out of the loop!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 4392, __PRETTY_FUNCTION__)) |
| 4392 | "Exiting block must actually branch out of the loop!")((L->isLoopExiting(ExitingBlock) && "Exiting block must actually branch out of the loop!" ) ? static_cast<void> (0) : __assert_fail ("L->isLoopExiting(ExitingBlock) && \"Exiting block must actually branch out of the loop!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 4392, __PRETTY_FUNCTION__)); |
| 4393 | const SCEVConstant *ExitCount = |
| 4394 | dyn_cast<SCEVConstant>(getExitCount(L, ExitingBlock)); |
| 4395 | if (!ExitCount) |
| 4396 | return 0; |
| 4397 | |
| 4398 | ConstantInt *ExitConst = ExitCount->getValue(); |
| 4399 | |
| 4400 | // Guard against huge trip counts. |
| 4401 | if (ExitConst->getValue().getActiveBits() > 32) |
| 4402 | return 0; |
| 4403 | |
| 4404 | // In case of integer overflow, this returns 0, which is correct. |
| 4405 | return ((unsigned)ExitConst->getZExtValue()) + 1; |
| 4406 | } |
| 4407 | |
| 4408 | unsigned ScalarEvolution::getSmallConstantTripMultiple(Loop *L) { |
| 4409 | if (BasicBlock *ExitingBB = L->getExitingBlock()) |
| 4410 | return getSmallConstantTripMultiple(L, ExitingBB); |
| 4411 | |
| 4412 | // No trip multiple information for multiple exits. |
| 4413 | return 0; |
| 4414 | } |
| 4415 | |
| 4416 | /// getSmallConstantTripMultiple - Returns the largest constant divisor of the |
| 4417 | /// trip count of this loop as a normal unsigned value, if possible. This |
| 4418 | /// means that the actual trip count is always a multiple of the returned |
| 4419 | /// value (don't forget the trip count could very well be zero as well!). |
| 4420 | /// |
| 4421 | /// Returns 1 if the trip count is unknown or not guaranteed to be the |
| 4422 | /// multiple of a constant (which is also the case if the trip count is simply |
| 4423 | /// constant, use getSmallConstantTripCount for that case), Will also return 1 |
| 4424 | /// if the trip count is very large (>= 2^32). |
| 4425 | /// |
| 4426 | /// As explained in the comments for getSmallConstantTripCount, this assumes |
| 4427 | /// that control exits the loop via ExitingBlock. |
| 4428 | unsigned |
| 4429 | ScalarEvolution::getSmallConstantTripMultiple(Loop *L, |
| 4430 | BasicBlock *ExitingBlock) { |
| 4431 | assert(ExitingBlock && "Must pass a non-null exiting block!")((ExitingBlock && "Must pass a non-null exiting block!" ) ? static_cast<void> (0) : __assert_fail ("ExitingBlock && \"Must pass a non-null exiting block!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 4431, __PRETTY_FUNCTION__)); |
| 4432 | assert(L->isLoopExiting(ExitingBlock) &&((L->isLoopExiting(ExitingBlock) && "Exiting block must actually branch out of the loop!" ) ? static_cast<void> (0) : __assert_fail ("L->isLoopExiting(ExitingBlock) && \"Exiting block must actually branch out of the loop!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 4433, __PRETTY_FUNCTION__)) |
| 4433 | "Exiting block must actually branch out of the loop!")((L->isLoopExiting(ExitingBlock) && "Exiting block must actually branch out of the loop!" ) ? static_cast<void> (0) : __assert_fail ("L->isLoopExiting(ExitingBlock) && \"Exiting block must actually branch out of the loop!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 4433, __PRETTY_FUNCTION__)); |
| 4434 | const SCEV *ExitCount = getExitCount(L, ExitingBlock); |
| 4435 | if (ExitCount == getCouldNotCompute()) |
| 4436 | return 1; |
| 4437 | |
| 4438 | // Get the trip count from the BE count by adding 1. |
| 4439 | const SCEV *TCMul = getAddExpr(ExitCount, |
| 4440 | getConstant(ExitCount->getType(), 1)); |
| 4441 | // FIXME: SCEV distributes multiplication as V1*C1 + V2*C1. We could attempt |
| 4442 | // to factor simple cases. |
| 4443 | if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(TCMul)) |
| 4444 | TCMul = Mul->getOperand(0); |
| 4445 | |
| 4446 | const SCEVConstant *MulC = dyn_cast<SCEVConstant>(TCMul); |
| 4447 | if (!MulC) |
| 4448 | return 1; |
| 4449 | |
| 4450 | ConstantInt *Result = MulC->getValue(); |
| 4451 | |
| 4452 | // Guard against huge trip counts (this requires checking |
| 4453 | // for zero to handle the case where the trip count == -1 and the |
| 4454 | // addition wraps). |
| 4455 | if (!Result || Result->getValue().getActiveBits() > 32 || |
| 4456 | Result->getValue().getActiveBits() == 0) |
| 4457 | return 1; |
| 4458 | |
| 4459 | return (unsigned)Result->getZExtValue(); |
| 4460 | } |
| 4461 | |
| 4462 | // getExitCount - Get the expression for the number of loop iterations for which |
| 4463 | // this loop is guaranteed not to exit via ExitingBlock. Otherwise return |
| 4464 | // SCEVCouldNotCompute. |
| 4465 | const SCEV *ScalarEvolution::getExitCount(Loop *L, BasicBlock *ExitingBlock) { |
| 4466 | return getBackedgeTakenInfo(L).getExact(ExitingBlock, this); |
| 4467 | } |
| 4468 | |
| 4469 | /// getBackedgeTakenCount - If the specified loop has a predictable |
| 4470 | /// backedge-taken count, return it, otherwise return a SCEVCouldNotCompute |
| 4471 | /// object. The backedge-taken count is the number of times the loop header |
| 4472 | /// will be branched to from within the loop. This is one less than the |
| 4473 | /// trip count of the loop, since it doesn't count the first iteration, |
| 4474 | /// when the header is branched to from outside the loop. |
| 4475 | /// |
| 4476 | /// Note that it is not valid to call this method on a loop without a |
| 4477 | /// loop-invariant backedge-taken count (see |
| 4478 | /// hasLoopInvariantBackedgeTakenCount). |
| 4479 | /// |
| 4480 | const SCEV *ScalarEvolution::getBackedgeTakenCount(const Loop *L) { |
| 4481 | return getBackedgeTakenInfo(L).getExact(this); |
| 4482 | } |
| 4483 | |
| 4484 | /// getMaxBackedgeTakenCount - Similar to getBackedgeTakenCount, except |
| 4485 | /// return the least SCEV value that is known never to be less than the |
| 4486 | /// actual backedge taken count. |
| 4487 | const SCEV *ScalarEvolution::getMaxBackedgeTakenCount(const Loop *L) { |
| 4488 | return getBackedgeTakenInfo(L).getMax(this); |
| 4489 | } |
| 4490 | |
| 4491 | /// PushLoopPHIs - Push PHI nodes in the header of the given loop |
| 4492 | /// onto the given Worklist. |
| 4493 | static void |
| 4494 | PushLoopPHIs(const Loop *L, SmallVectorImpl<Instruction *> &Worklist) { |
| 4495 | BasicBlock *Header = L->getHeader(); |
| 4496 | |
| 4497 | // Push all Loop-header PHIs onto the Worklist stack. |
| 4498 | for (BasicBlock::iterator I = Header->begin(); |
| 4499 | PHINode *PN = dyn_cast<PHINode>(I); ++I) |
| 4500 | Worklist.push_back(PN); |
| 4501 | } |
| 4502 | |
| 4503 | const ScalarEvolution::BackedgeTakenInfo & |
| 4504 | ScalarEvolution::getBackedgeTakenInfo(const Loop *L) { |
| 4505 | // Initially insert an invalid entry for this loop. If the insertion |
| 4506 | // succeeds, proceed to actually compute a backedge-taken count and |
| 4507 | // update the value. The temporary CouldNotCompute value tells SCEV |
| 4508 | // code elsewhere that it shouldn't attempt to request a new |
| 4509 | // backedge-taken count, which could result in infinite recursion. |
| 4510 | std::pair<DenseMap<const Loop *, BackedgeTakenInfo>::iterator, bool> Pair = |
| 4511 | BackedgeTakenCounts.insert(std::make_pair(L, BackedgeTakenInfo())); |
| 4512 | if (!Pair.second) |
| 4513 | return Pair.first->second; |
| 4514 | |
| 4515 | // ComputeBackedgeTakenCount may allocate memory for its result. Inserting it |
| 4516 | // into the BackedgeTakenCounts map transfers ownership. Otherwise, the result |
| 4517 | // must be cleared in this scope. |
| 4518 | BackedgeTakenInfo Result = ComputeBackedgeTakenCount(L); |
| 4519 | |
| 4520 | if (Result.getExact(this) != getCouldNotCompute()) { |
| 4521 | assert(isLoopInvariant(Result.getExact(this), L) &&((isLoopInvariant(Result.getExact(this), L) && isLoopInvariant (Result.getMax(this), L) && "Computed backedge-taken count isn't loop invariant for loop!" ) ? static_cast<void> (0) : __assert_fail ("isLoopInvariant(Result.getExact(this), L) && isLoopInvariant(Result.getMax(this), L) && \"Computed backedge-taken count isn't loop invariant for loop!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 4523, __PRETTY_FUNCTION__)) |
| 4522 | isLoopInvariant(Result.getMax(this), L) &&((isLoopInvariant(Result.getExact(this), L) && isLoopInvariant (Result.getMax(this), L) && "Computed backedge-taken count isn't loop invariant for loop!" ) ? static_cast<void> (0) : __assert_fail ("isLoopInvariant(Result.getExact(this), L) && isLoopInvariant(Result.getMax(this), L) && \"Computed backedge-taken count isn't loop invariant for loop!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 4523, __PRETTY_FUNCTION__)) |
| 4523 | "Computed backedge-taken count isn't loop invariant for loop!")((isLoopInvariant(Result.getExact(this), L) && isLoopInvariant (Result.getMax(this), L) && "Computed backedge-taken count isn't loop invariant for loop!" ) ? static_cast<void> (0) : __assert_fail ("isLoopInvariant(Result.getExact(this), L) && isLoopInvariant(Result.getMax(this), L) && \"Computed backedge-taken count isn't loop invariant for loop!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 4523, __PRETTY_FUNCTION__)); |
| 4524 | ++NumTripCountsComputed; |
| 4525 | } |
| 4526 | else if (Result.getMax(this) == getCouldNotCompute() && |
| 4527 | isa<PHINode>(L->getHeader()->begin())) { |
| 4528 | // Only count loops that have phi nodes as not being computable. |
| 4529 | ++NumTripCountsNotComputed; |
| 4530 | } |
| 4531 | |
| 4532 | // Now that we know more about the trip count for this loop, forget any |
| 4533 | // existing SCEV values for PHI nodes in this loop since they are only |
| 4534 | // conservative estimates made without the benefit of trip count |
| 4535 | // information. This is similar to the code in forgetLoop, except that |
| 4536 | // it handles SCEVUnknown PHI nodes specially. |
| 4537 | if (Result.hasAnyInfo()) { |
| 4538 | SmallVector<Instruction *, 16> Worklist; |
| 4539 | PushLoopPHIs(L, Worklist); |
| 4540 | |
| 4541 | SmallPtrSet<Instruction *, 8> Visited; |
| 4542 | while (!Worklist.empty()) { |
| 4543 | Instruction *I = Worklist.pop_back_val(); |
| 4544 | if (!Visited.insert(I)) continue; |
| 4545 | |
| 4546 | ValueExprMapType::iterator It = |
| 4547 | ValueExprMap.find_as(static_cast<Value *>(I)); |
| 4548 | if (It != ValueExprMap.end()) { |
| 4549 | const SCEV *Old = It->second; |
| 4550 | |
| 4551 | // SCEVUnknown for a PHI either means that it has an unrecognized |
| 4552 | // structure, or it's a PHI that's in the progress of being computed |
| 4553 | // by createNodeForPHI. In the former case, additional loop trip |
| 4554 | // count information isn't going to change anything. In the later |
| 4555 | // case, createNodeForPHI will perform the necessary updates on its |
| 4556 | // own when it gets to that point. |
| 4557 | if (!isa<PHINode>(I) || !isa<SCEVUnknown>(Old)) { |
| 4558 | forgetMemoizedResults(Old); |
| 4559 | ValueExprMap.erase(It); |
| 4560 | } |
| 4561 | if (PHINode *PN = dyn_cast<PHINode>(I)) |
| 4562 | ConstantEvolutionLoopExitValue.erase(PN); |
| 4563 | } |
| 4564 | |
| 4565 | PushDefUseChildren(I, Worklist); |
| 4566 | } |
| 4567 | } |
| 4568 | |
| 4569 | // Re-lookup the insert position, since the call to |
| 4570 | // ComputeBackedgeTakenCount above could result in a |
| 4571 | // recusive call to getBackedgeTakenInfo (on a different |
| 4572 | // loop), which would invalidate the iterator computed |
| 4573 | // earlier. |
| 4574 | return BackedgeTakenCounts.find(L)->second = Result; |
| 4575 | } |
| 4576 | |
| 4577 | /// forgetLoop - This method should be called by the client when it has |
| 4578 | /// changed a loop in a way that may effect ScalarEvolution's ability to |
| 4579 | /// compute a trip count, or if the loop is deleted. |
| 4580 | void ScalarEvolution::forgetLoop(const Loop *L) { |
| 4581 | // Drop any stored trip count value. |
| 4582 | DenseMap<const Loop*, BackedgeTakenInfo>::iterator BTCPos = |
| 4583 | BackedgeTakenCounts.find(L); |
| 4584 | if (BTCPos != BackedgeTakenCounts.end()) { |
| 4585 | BTCPos->second.clear(); |
| 4586 | BackedgeTakenCounts.erase(BTCPos); |
| 4587 | } |
| 4588 | |
| 4589 | // Drop information about expressions based on loop-header PHIs. |
| 4590 | SmallVector<Instruction *, 16> Worklist; |
| 4591 | PushLoopPHIs(L, Worklist); |
| 4592 | |
| 4593 | SmallPtrSet<Instruction *, 8> Visited; |
| 4594 | while (!Worklist.empty()) { |
| 4595 | Instruction *I = Worklist.pop_back_val(); |
| 4596 | if (!Visited.insert(I)) continue; |
| 4597 | |
| 4598 | ValueExprMapType::iterator It = |
| 4599 | ValueExprMap.find_as(static_cast<Value *>(I)); |
| 4600 | if (It != ValueExprMap.end()) { |
| 4601 | forgetMemoizedResults(It->second); |
| 4602 | ValueExprMap.erase(It); |
| 4603 | if (PHINode *PN = dyn_cast<PHINode>(I)) |
| 4604 | ConstantEvolutionLoopExitValue.erase(PN); |
| 4605 | } |
| 4606 | |
| 4607 | PushDefUseChildren(I, Worklist); |
| 4608 | } |
| 4609 | |
| 4610 | // Forget all contained loops too, to avoid dangling entries in the |
| 4611 | // ValuesAtScopes map. |
| 4612 | for (Loop::iterator I = L->begin(), E = L->end(); I != E; ++I) |
| 4613 | forgetLoop(*I); |
| 4614 | } |
| 4615 | |
| 4616 | /// forgetValue - This method should be called by the client when it has |
| 4617 | /// changed a value in a way that may effect its value, or which may |
| 4618 | /// disconnect it from a def-use chain linking it to a loop. |
| 4619 | void ScalarEvolution::forgetValue(Value *V) { |
| 4620 | Instruction *I = dyn_cast<Instruction>(V); |
| 4621 | if (!I) return; |
| 4622 | |
| 4623 | // Drop information about expressions based on loop-header PHIs. |
| 4624 | SmallVector<Instruction *, 16> Worklist; |
| 4625 | Worklist.push_back(I); |
| 4626 | |
| 4627 | SmallPtrSet<Instruction *, 8> Visited; |
| 4628 | while (!Worklist.empty()) { |
| 4629 | I = Worklist.pop_back_val(); |
| 4630 | if (!Visited.insert(I)) continue; |
| 4631 | |
| 4632 | ValueExprMapType::iterator It = |
| 4633 | ValueExprMap.find_as(static_cast<Value *>(I)); |
| 4634 | if (It != ValueExprMap.end()) { |
| 4635 | forgetMemoizedResults(It->second); |
| 4636 | ValueExprMap.erase(It); |
| 4637 | if (PHINode *PN = dyn_cast<PHINode>(I)) |
| 4638 | ConstantEvolutionLoopExitValue.erase(PN); |
| 4639 | } |
| 4640 | |
| 4641 | PushDefUseChildren(I, Worklist); |
| 4642 | } |
| 4643 | } |
| 4644 | |
| 4645 | /// getExact - Get the exact loop backedge taken count considering all loop |
| 4646 | /// exits. A computable result can only be return for loops with a single exit. |
| 4647 | /// Returning the minimum taken count among all exits is incorrect because one |
| 4648 | /// of the loop's exit limit's may have been skipped. HowFarToZero assumes that |
| 4649 | /// the limit of each loop test is never skipped. This is a valid assumption as |
| 4650 | /// long as the loop exits via that test. For precise results, it is the |
| 4651 | /// caller's responsibility to specify the relevant loop exit using |
| 4652 | /// getExact(ExitingBlock, SE). |
| 4653 | const SCEV * |
| 4654 | ScalarEvolution::BackedgeTakenInfo::getExact(ScalarEvolution *SE) const { |
| 4655 | // If any exits were not computable, the loop is not computable. |
| 4656 | if (!ExitNotTaken.isCompleteList()) return SE->getCouldNotCompute(); |
| 4657 | |
| 4658 | // We need exactly one computable exit. |
| 4659 | if (!ExitNotTaken.ExitingBlock) return SE->getCouldNotCompute(); |
| 4660 | assert(ExitNotTaken.ExactNotTaken && "uninitialized not-taken info")((ExitNotTaken.ExactNotTaken && "uninitialized not-taken info" ) ? static_cast<void> (0) : __assert_fail ("ExitNotTaken.ExactNotTaken && \"uninitialized not-taken info\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 4660, __PRETTY_FUNCTION__)); |
| 4661 | |
| 4662 | const SCEV *BECount = nullptr; |
| 4663 | for (const ExitNotTakenInfo *ENT = &ExitNotTaken; |
| 4664 | ENT != nullptr; ENT = ENT->getNextExit()) { |
| 4665 | |
| 4666 | assert(ENT->ExactNotTaken != SE->getCouldNotCompute() && "bad exit SCEV")((ENT->ExactNotTaken != SE->getCouldNotCompute() && "bad exit SCEV") ? static_cast<void> (0) : __assert_fail ("ENT->ExactNotTaken != SE->getCouldNotCompute() && \"bad exit SCEV\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 4666, __PRETTY_FUNCTION__)); |
| 4667 | |
| 4668 | if (!BECount) |
| 4669 | BECount = ENT->ExactNotTaken; |
| 4670 | else if (BECount != ENT->ExactNotTaken) |
| 4671 | return SE->getCouldNotCompute(); |
| 4672 | } |
| 4673 | assert(BECount && "Invalid not taken count for loop exit")((BECount && "Invalid not taken count for loop exit") ? static_cast<void> (0) : __assert_fail ("BECount && \"Invalid not taken count for loop exit\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 4673, __PRETTY_FUNCTION__)); |
| 4674 | return BECount; |
| 4675 | } |
| 4676 | |
| 4677 | /// getExact - Get the exact not taken count for this loop exit. |
| 4678 | const SCEV * |
| 4679 | ScalarEvolution::BackedgeTakenInfo::getExact(BasicBlock *ExitingBlock, |
| 4680 | ScalarEvolution *SE) const { |
| 4681 | for (const ExitNotTakenInfo *ENT = &ExitNotTaken; |
| 4682 | ENT != nullptr; ENT = ENT->getNextExit()) { |
| 4683 | |
| 4684 | if (ENT->ExitingBlock == ExitingBlock) |
| 4685 | return ENT->ExactNotTaken; |
| 4686 | } |
| 4687 | return SE->getCouldNotCompute(); |
| 4688 | } |
| 4689 | |
| 4690 | /// getMax - Get the max backedge taken count for the loop. |
| 4691 | const SCEV * |
| 4692 | ScalarEvolution::BackedgeTakenInfo::getMax(ScalarEvolution *SE) const { |
| 4693 | return Max ? Max : SE->getCouldNotCompute(); |
| 4694 | } |
| 4695 | |
| 4696 | bool ScalarEvolution::BackedgeTakenInfo::hasOperand(const SCEV *S, |
| 4697 | ScalarEvolution *SE) const { |
| 4698 | if (Max && Max != SE->getCouldNotCompute() && SE->hasOperand(Max, S)) |
| 4699 | return true; |
| 4700 | |
| 4701 | if (!ExitNotTaken.ExitingBlock) |
| 4702 | return false; |
| 4703 | |
| 4704 | for (const ExitNotTakenInfo *ENT = &ExitNotTaken; |
| 4705 | ENT != nullptr; ENT = ENT->getNextExit()) { |
| 4706 | |
| 4707 | if (ENT->ExactNotTaken != SE->getCouldNotCompute() |
| 4708 | && SE->hasOperand(ENT->ExactNotTaken, S)) { |
| 4709 | return true; |
| 4710 | } |
| 4711 | } |
| 4712 | return false; |
| 4713 | } |
| 4714 | |
| 4715 | /// Allocate memory for BackedgeTakenInfo and copy the not-taken count of each |
| 4716 | /// computable exit into a persistent ExitNotTakenInfo array. |
| 4717 | ScalarEvolution::BackedgeTakenInfo::BackedgeTakenInfo( |
| 4718 | SmallVectorImpl< std::pair<BasicBlock *, const SCEV *> > &ExitCounts, |
| 4719 | bool Complete, const SCEV *MaxCount) : Max(MaxCount) { |
| 4720 | |
| 4721 | if (!Complete) |
| 4722 | ExitNotTaken.setIncomplete(); |
| 4723 | |
| 4724 | unsigned NumExits = ExitCounts.size(); |
| 4725 | if (NumExits == 0) return; |
| 4726 | |
| 4727 | ExitNotTaken.ExitingBlock = ExitCounts[0].first; |
| 4728 | ExitNotTaken.ExactNotTaken = ExitCounts[0].second; |
| 4729 | if (NumExits == 1) return; |
| 4730 | |
| 4731 | // Handle the rare case of multiple computable exits. |
| 4732 | ExitNotTakenInfo *ENT = new ExitNotTakenInfo[NumExits-1]; |
| 4733 | |
| 4734 | ExitNotTakenInfo *PrevENT = &ExitNotTaken; |
| 4735 | for (unsigned i = 1; i < NumExits; ++i, PrevENT = ENT, ++ENT) { |
| 4736 | PrevENT->setNextExit(ENT); |
| 4737 | ENT->ExitingBlock = ExitCounts[i].first; |
| 4738 | ENT->ExactNotTaken = ExitCounts[i].second; |
| 4739 | } |
| 4740 | } |
| 4741 | |
| 4742 | /// clear - Invalidate this result and free the ExitNotTakenInfo array. |
| 4743 | void ScalarEvolution::BackedgeTakenInfo::clear() { |
| 4744 | ExitNotTaken.ExitingBlock = nullptr; |
| 4745 | ExitNotTaken.ExactNotTaken = nullptr; |
| 4746 | delete[] ExitNotTaken.getNextExit(); |
| 4747 | } |
| 4748 | |
| 4749 | /// ComputeBackedgeTakenCount - Compute the number of times the backedge |
| 4750 | /// of the specified loop will execute. |
| 4751 | ScalarEvolution::BackedgeTakenInfo |
| 4752 | ScalarEvolution::ComputeBackedgeTakenCount(const Loop *L) { |
| 4753 | SmallVector<BasicBlock *, 8> ExitingBlocks; |
| 4754 | L->getExitingBlocks(ExitingBlocks); |
| 4755 | |
| 4756 | SmallVector<std::pair<BasicBlock *, const SCEV *>, 4> ExitCounts; |
| 4757 | bool CouldComputeBECount = true; |
| 4758 | BasicBlock *Latch = L->getLoopLatch(); // may be NULL. |
| 4759 | const SCEV *MustExitMaxBECount = nullptr; |
| 4760 | const SCEV *MayExitMaxBECount = nullptr; |
| 4761 | |
| 4762 | // Compute the ExitLimit for each loop exit. Use this to populate ExitCounts |
| 4763 | // and compute maxBECount. |
| 4764 | for (unsigned i = 0, e = ExitingBlocks.size(); i != e; ++i) { |
| 4765 | BasicBlock *ExitBB = ExitingBlocks[i]; |
| 4766 | ExitLimit EL = ComputeExitLimit(L, ExitBB); |
| 4767 | |
| 4768 | // 1. For each exit that can be computed, add an entry to ExitCounts. |
| 4769 | // CouldComputeBECount is true only if all exits can be computed. |
| 4770 | if (EL.Exact == getCouldNotCompute()) |
| 4771 | // We couldn't compute an exact value for this exit, so |
| 4772 | // we won't be able to compute an exact value for the loop. |
| 4773 | CouldComputeBECount = false; |
| 4774 | else |
| 4775 | ExitCounts.push_back(std::make_pair(ExitBB, EL.Exact)); |
| 4776 | |
| 4777 | // 2. Derive the loop's MaxBECount from each exit's max number of |
| 4778 | // non-exiting iterations. Partition the loop exits into two kinds: |
| 4779 | // LoopMustExits and LoopMayExits. |
| 4780 | // |
| 4781 | // If the exit dominates the loop latch, it is a LoopMustExit otherwise it |
| 4782 | // is a LoopMayExit. If any computable LoopMustExit is found, then |
| 4783 | // MaxBECount is the minimum EL.Max of computable LoopMustExits. Otherwise, |
| 4784 | // MaxBECount is conservatively the maximum EL.Max, where CouldNotCompute is |
| 4785 | // considered greater than any computable EL.Max. |
| 4786 | if (EL.Max != getCouldNotCompute() && Latch && |
| 4787 | DT->dominates(ExitBB, Latch)) { |
| 4788 | if (!MustExitMaxBECount) |
| 4789 | MustExitMaxBECount = EL.Max; |
| 4790 | else { |
| 4791 | MustExitMaxBECount = |
| 4792 | getUMinFromMismatchedTypes(MustExitMaxBECount, EL.Max); |
| 4793 | } |
| 4794 | } else if (MayExitMaxBECount != getCouldNotCompute()) { |
| 4795 | if (!MayExitMaxBECount || EL.Max == getCouldNotCompute()) |
| 4796 | MayExitMaxBECount = EL.Max; |
| 4797 | else { |
| 4798 | MayExitMaxBECount = |
| 4799 | getUMaxFromMismatchedTypes(MayExitMaxBECount, EL.Max); |
| 4800 | } |
| 4801 | } |
| 4802 | } |
| 4803 | const SCEV *MaxBECount = MustExitMaxBECount ? MustExitMaxBECount : |
| 4804 | (MayExitMaxBECount ? MayExitMaxBECount : getCouldNotCompute()); |
| 4805 | return BackedgeTakenInfo(ExitCounts, CouldComputeBECount, MaxBECount); |
| 4806 | } |
| 4807 | |
| 4808 | /// ComputeExitLimit - Compute the number of times the backedge of the specified |
| 4809 | /// loop will execute if it exits via the specified block. |
| 4810 | ScalarEvolution::ExitLimit |
| 4811 | ScalarEvolution::ComputeExitLimit(const Loop *L, BasicBlock *ExitingBlock) { |
| 4812 | |
| 4813 | // Okay, we've chosen an exiting block. See what condition causes us to |
| 4814 | // exit at this block and remember the exit block and whether all other targets |
| 4815 | // lead to the loop header. |
| 4816 | bool MustExecuteLoopHeader = true; |
| 4817 | BasicBlock *Exit = nullptr; |
| 4818 | for (succ_iterator SI = succ_begin(ExitingBlock), SE = succ_end(ExitingBlock); |
| 4819 | SI != SE; ++SI) |
| 4820 | if (!L->contains(*SI)) { |
| 4821 | if (Exit) // Multiple exit successors. |
| 4822 | return getCouldNotCompute(); |
| 4823 | Exit = *SI; |
| 4824 | } else if (*SI != L->getHeader()) { |
| 4825 | MustExecuteLoopHeader = false; |
| 4826 | } |
| 4827 | |
| 4828 | // At this point, we know we have a conditional branch that determines whether |
| 4829 | // the loop is exited. However, we don't know if the branch is executed each |
| 4830 | // time through the loop. If not, then the execution count of the branch will |
| 4831 | // not be equal to the trip count of the loop. |
| 4832 | // |
| 4833 | // Currently we check for this by checking to see if the Exit branch goes to |
| 4834 | // the loop header. If so, we know it will always execute the same number of |
| 4835 | // times as the loop. We also handle the case where the exit block *is* the |
| 4836 | // loop header. This is common for un-rotated loops. |
| 4837 | // |
| 4838 | // If both of those tests fail, walk up the unique predecessor chain to the |
| 4839 | // header, stopping if there is an edge that doesn't exit the loop. If the |
| 4840 | // header is reached, the execution count of the branch will be equal to the |
| 4841 | // trip count of the loop. |
| 4842 | // |
| 4843 | // More extensive analysis could be done to handle more cases here. |
| 4844 | // |
| 4845 | if (!MustExecuteLoopHeader && ExitingBlock != L->getHeader()) { |
| 4846 | // The simple checks failed, try climbing the unique predecessor chain |
| 4847 | // up to the header. |
| 4848 | bool Ok = false; |
| 4849 | for (BasicBlock *BB = ExitingBlock; BB; ) { |
| 4850 | BasicBlock *Pred = BB->getUniquePredecessor(); |
| 4851 | if (!Pred) |
| 4852 | return getCouldNotCompute(); |
| 4853 | TerminatorInst *PredTerm = Pred->getTerminator(); |
| 4854 | for (unsigned i = 0, e = PredTerm->getNumSuccessors(); i != e; ++i) { |
| 4855 | BasicBlock *PredSucc = PredTerm->getSuccessor(i); |
| 4856 | if (PredSucc == BB) |
| 4857 | continue; |
| 4858 | // If the predecessor has a successor that isn't BB and isn't |
| 4859 | // outside the loop, assume the worst. |
| 4860 | if (L->contains(PredSucc)) |
| 4861 | return getCouldNotCompute(); |
| 4862 | } |
| 4863 | if (Pred == L->getHeader()) { |
| 4864 | Ok = true; |
| 4865 | break; |
| 4866 | } |
| 4867 | BB = Pred; |
| 4868 | } |
| 4869 | if (!Ok) |
| 4870 | return getCouldNotCompute(); |
| 4871 | } |
| 4872 | |
| 4873 | bool IsOnlyExit = (L->getExitingBlock() != nullptr); |
| 4874 | TerminatorInst *Term = ExitingBlock->getTerminator(); |
| 4875 | if (BranchInst *BI = dyn_cast<BranchInst>(Term)) { |
| 4876 | assert(BI->isConditional() && "If unconditional, it can't be in loop!")((BI->isConditional() && "If unconditional, it can't be in loop!" ) ? static_cast<void> (0) : __assert_fail ("BI->isConditional() && \"If unconditional, it can't be in loop!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 4876, __PRETTY_FUNCTION__)); |
| 4877 | // Proceed to the next level to examine the exit condition expression. |
| 4878 | return ComputeExitLimitFromCond(L, BI->getCondition(), BI->getSuccessor(0), |
| 4879 | BI->getSuccessor(1), |
| 4880 | /*ControlsExit=*/IsOnlyExit); |
| 4881 | } |
| 4882 | |
| 4883 | if (SwitchInst *SI = dyn_cast<SwitchInst>(Term)) |
| 4884 | return ComputeExitLimitFromSingleExitSwitch(L, SI, Exit, |
| 4885 | /*ControlsExit=*/IsOnlyExit); |
| 4886 | |
| 4887 | return getCouldNotCompute(); |
| 4888 | } |
| 4889 | |
| 4890 | /// ComputeExitLimitFromCond - Compute the number of times the |
| 4891 | /// backedge of the specified loop will execute if its exit condition |
| 4892 | /// were a conditional branch of ExitCond, TBB, and FBB. |
| 4893 | /// |
| 4894 | /// @param ControlsExit is true if ExitCond directly controls the exit |
| 4895 | /// branch. In this case, we can assume that the loop exits only if the |
| 4896 | /// condition is true and can infer that failing to meet the condition prior to |
| 4897 | /// integer wraparound results in undefined behavior. |
| 4898 | ScalarEvolution::ExitLimit |
| 4899 | ScalarEvolution::ComputeExitLimitFromCond(const Loop *L, |
| 4900 | Value *ExitCond, |
| 4901 | BasicBlock *TBB, |
| 4902 | BasicBlock *FBB, |
| 4903 | bool ControlsExit) { |
| 4904 | // Check if the controlling expression for this loop is an And or Or. |
| 4905 | if (BinaryOperator *BO = dyn_cast<BinaryOperator>(ExitCond)) { |
| 4906 | if (BO->getOpcode() == Instruction::And) { |
| 4907 | // Recurse on the operands of the and. |
| 4908 | bool EitherMayExit = L->contains(TBB); |
| 4909 | ExitLimit EL0 = ComputeExitLimitFromCond(L, BO->getOperand(0), TBB, FBB, |
| 4910 | ControlsExit && !EitherMayExit); |
| 4911 | ExitLimit EL1 = ComputeExitLimitFromCond(L, BO->getOperand(1), TBB, FBB, |
| 4912 | ControlsExit && !EitherMayExit); |
| 4913 | const SCEV *BECount = getCouldNotCompute(); |
| 4914 | const SCEV *MaxBECount = getCouldNotCompute(); |
| 4915 | if (EitherMayExit) { |
| 4916 | // Both conditions must be true for the loop to continue executing. |
| 4917 | // Choose the less conservative count. |
| 4918 | if (EL0.Exact == getCouldNotCompute() || |
| 4919 | EL1.Exact == getCouldNotCompute()) |
| 4920 | BECount = getCouldNotCompute(); |
| 4921 | else |
| 4922 | BECount = getUMinFromMismatchedTypes(EL0.Exact, EL1.Exact); |
| 4923 | if (EL0.Max == getCouldNotCompute()) |
| 4924 | MaxBECount = EL1.Max; |
| 4925 | else if (EL1.Max == getCouldNotCompute()) |
| 4926 | MaxBECount = EL0.Max; |
| 4927 | else |
| 4928 | MaxBECount = getUMinFromMismatchedTypes(EL0.Max, EL1.Max); |
| 4929 | } else { |
| 4930 | // Both conditions must be true at the same time for the loop to exit. |
| 4931 | // For now, be conservative. |
| 4932 | assert(L->contains(FBB) && "Loop block has no successor in loop!")((L->contains(FBB) && "Loop block has no successor in loop!" ) ? static_cast<void> (0) : __assert_fail ("L->contains(FBB) && \"Loop block has no successor in loop!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 4932, __PRETTY_FUNCTION__)); |
| 4933 | if (EL0.Max == EL1.Max) |
| 4934 | MaxBECount = EL0.Max; |
| 4935 | if (EL0.Exact == EL1.Exact) |
| 4936 | BECount = EL0.Exact; |
| 4937 | } |
| 4938 | |
| 4939 | return ExitLimit(BECount, MaxBECount); |
| 4940 | } |
| 4941 | if (BO->getOpcode() == Instruction::Or) { |
| 4942 | // Recurse on the operands of the or. |
| 4943 | bool EitherMayExit = L->contains(FBB); |
| 4944 | ExitLimit EL0 = ComputeExitLimitFromCond(L, BO->getOperand(0), TBB, FBB, |
| 4945 | ControlsExit && !EitherMayExit); |
| 4946 | ExitLimit EL1 = ComputeExitLimitFromCond(L, BO->getOperand(1), TBB, FBB, |
| 4947 | ControlsExit && !EitherMayExit); |
| 4948 | const SCEV *BECount = getCouldNotCompute(); |
| 4949 | const SCEV *MaxBECount = getCouldNotCompute(); |
| 4950 | if (EitherMayExit) { |
| 4951 | // Both conditions must be false for the loop to continue executing. |
| 4952 | // Choose the less conservative count. |
| 4953 | if (EL0.Exact == getCouldNotCompute() || |
| 4954 | EL1.Exact == getCouldNotCompute()) |
| 4955 | BECount = getCouldNotCompute(); |
| 4956 | else |
| 4957 | BECount = getUMinFromMismatchedTypes(EL0.Exact, EL1.Exact); |
| 4958 | if (EL0.Max == getCouldNotCompute()) |
| 4959 | MaxBECount = EL1.Max; |
| 4960 | else if (EL1.Max == getCouldNotCompute()) |
| 4961 | MaxBECount = EL0.Max; |
| 4962 | else |
| 4963 | MaxBECount = getUMinFromMismatchedTypes(EL0.Max, EL1.Max); |
| 4964 | } else { |
| 4965 | // Both conditions must be false at the same time for the loop to exit. |
| 4966 | // For now, be conservative. |
| 4967 | assert(L->contains(TBB) && "Loop block has no successor in loop!")((L->contains(TBB) && "Loop block has no successor in loop!" ) ? static_cast<void> (0) : __assert_fail ("L->contains(TBB) && \"Loop block has no successor in loop!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 4967, __PRETTY_FUNCTION__)); |
| 4968 | if (EL0.Max == EL1.Max) |
| 4969 | MaxBECount = EL0.Max; |
| 4970 | if (EL0.Exact == EL1.Exact) |
| 4971 | BECount = EL0.Exact; |
| 4972 | } |
| 4973 | |
| 4974 | return ExitLimit(BECount, MaxBECount); |
| 4975 | } |
| 4976 | } |
| 4977 | |
| 4978 | // With an icmp, it may be feasible to compute an exact backedge-taken count. |
| 4979 | // Proceed to the next level to examine the icmp. |
| 4980 | if (ICmpInst *ExitCondICmp = dyn_cast<ICmpInst>(ExitCond)) |
| 4981 | return ComputeExitLimitFromICmp(L, ExitCondICmp, TBB, FBB, ControlsExit); |
| 4982 | |
| 4983 | // Check for a constant condition. These are normally stripped out by |
| 4984 | // SimplifyCFG, but ScalarEvolution may be used by a pass which wishes to |
| 4985 | // preserve the CFG and is temporarily leaving constant conditions |
| 4986 | // in place. |
| 4987 | if (ConstantInt *CI = dyn_cast<ConstantInt>(ExitCond)) { |
| 4988 | if (L->contains(FBB) == !CI->getZExtValue()) |
| 4989 | // The backedge is always taken. |
| 4990 | return getCouldNotCompute(); |
| 4991 | else |
| 4992 | // The backedge is never taken. |
| 4993 | return getConstant(CI->getType(), 0); |
| 4994 | } |
| 4995 | |
| 4996 | // If it's not an integer or pointer comparison then compute it the hard way. |
| 4997 | return ComputeExitCountExhaustively(L, ExitCond, !L->contains(TBB)); |
| 4998 | } |
| 4999 | |
| 5000 | /// ComputeExitLimitFromICmp - Compute the number of times the |
| 5001 | /// backedge of the specified loop will execute if its exit condition |
| 5002 | /// were a conditional branch of the ICmpInst ExitCond, TBB, and FBB. |
| 5003 | ScalarEvolution::ExitLimit |
| 5004 | ScalarEvolution::ComputeExitLimitFromICmp(const Loop *L, |
| 5005 | ICmpInst *ExitCond, |
| 5006 | BasicBlock *TBB, |
| 5007 | BasicBlock *FBB, |
| 5008 | bool ControlsExit) { |
| 5009 | |
| 5010 | // If the condition was exit on true, convert the condition to exit on false |
| 5011 | ICmpInst::Predicate Cond; |
| 5012 | if (!L->contains(FBB)) |
| 5013 | Cond = ExitCond->getPredicate(); |
| 5014 | else |
| 5015 | Cond = ExitCond->getInversePredicate(); |
| 5016 | |
| 5017 | // Handle common loops like: for (X = "string"; *X; ++X) |
| 5018 | if (LoadInst *LI = dyn_cast<LoadInst>(ExitCond->getOperand(0))) |
| 5019 | if (Constant *RHS = dyn_cast<Constant>(ExitCond->getOperand(1))) { |
| 5020 | ExitLimit ItCnt = |
| 5021 | ComputeLoadConstantCompareExitLimit(LI, RHS, L, Cond); |
| 5022 | if (ItCnt.hasAnyInfo()) |
| 5023 | return ItCnt; |
| 5024 | } |
| 5025 | |
| 5026 | const SCEV *LHS = getSCEV(ExitCond->getOperand(0)); |
| 5027 | const SCEV *RHS = getSCEV(ExitCond->getOperand(1)); |
| 5028 | |
| 5029 | // Try to evaluate any dependencies out of the loop. |
| 5030 | LHS = getSCEVAtScope(LHS, L); |
| 5031 | RHS = getSCEVAtScope(RHS, L); |
| 5032 | |
| 5033 | // At this point, we would like to compute how many iterations of the |
| 5034 | // loop the predicate will return true for these inputs. |
| 5035 | if (isLoopInvariant(LHS, L) && !isLoopInvariant(RHS, L)) { |
| 5036 | // If there is a loop-invariant, force it into the RHS. |
| 5037 | std::swap(LHS, RHS); |
| 5038 | Cond = ICmpInst::getSwappedPredicate(Cond); |
| 5039 | } |
| 5040 | |
| 5041 | // Simplify the operands before analyzing them. |
| 5042 | (void)SimplifyICmpOperands(Cond, LHS, RHS); |
| 5043 | |
| 5044 | // If we have a comparison of a chrec against a constant, try to use value |
| 5045 | // ranges to answer this query. |
| 5046 | if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS)) |
| 5047 | if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(LHS)) |
| 5048 | if (AddRec->getLoop() == L) { |
| 5049 | // Form the constant range. |
| 5050 | ConstantRange CompRange( |
| 5051 | ICmpInst::makeConstantRange(Cond, RHSC->getValue()->getValue())); |
| 5052 | |
| 5053 | const SCEV *Ret = AddRec->getNumIterationsInRange(CompRange, *this); |
| 5054 | if (!isa<SCEVCouldNotCompute>(Ret)) return Ret; |
| 5055 | } |
| 5056 | |
| 5057 | switch (Cond) { |
| 5058 | case ICmpInst::ICMP_NE: { // while (X != Y) |
| 5059 | // Convert to: while (X-Y != 0) |
| 5060 | ExitLimit EL = HowFarToZero(getMinusSCEV(LHS, RHS), L, ControlsExit); |
| 5061 | if (EL.hasAnyInfo()) return EL; |
| 5062 | break; |
| 5063 | } |
| 5064 | case ICmpInst::ICMP_EQ: { // while (X == Y) |
| 5065 | // Convert to: while (X-Y == 0) |
| 5066 | ExitLimit EL = HowFarToNonZero(getMinusSCEV(LHS, RHS), L); |
| 5067 | if (EL.hasAnyInfo()) return EL; |
| 5068 | break; |
| 5069 | } |
| 5070 | case ICmpInst::ICMP_SLT: |
| 5071 | case ICmpInst::ICMP_ULT: { // while (X < Y) |
| 5072 | bool IsSigned = Cond == ICmpInst::ICMP_SLT; |
| 5073 | ExitLimit EL = HowManyLessThans(LHS, RHS, L, IsSigned, ControlsExit); |
| 5074 | if (EL.hasAnyInfo()) return EL; |
| 5075 | break; |
| 5076 | } |
| 5077 | case ICmpInst::ICMP_SGT: |
| 5078 | case ICmpInst::ICMP_UGT: { // while (X > Y) |
| 5079 | bool IsSigned = Cond == ICmpInst::ICMP_SGT; |
| 5080 | ExitLimit EL = HowManyGreaterThans(LHS, RHS, L, IsSigned, ControlsExit); |
| 5081 | if (EL.hasAnyInfo()) return EL; |
| 5082 | break; |
| 5083 | } |
| 5084 | default: |
| 5085 | #if 0 |
| 5086 | dbgs() << "ComputeBackedgeTakenCount "; |
| 5087 | if (ExitCond->getOperand(0)->getType()->isUnsigned()) |
| 5088 | dbgs() << "[unsigned] "; |
| 5089 | dbgs() << *LHS << " " |
| 5090 | << Instruction::getOpcodeName(Instruction::ICmp) |
| 5091 | << " " << *RHS << "\n"; |
| 5092 | #endif |
| 5093 | break; |
| 5094 | } |
| 5095 | return ComputeExitCountExhaustively(L, ExitCond, !L->contains(TBB)); |
| 5096 | } |
| 5097 | |
| 5098 | ScalarEvolution::ExitLimit |
| 5099 | ScalarEvolution::ComputeExitLimitFromSingleExitSwitch(const Loop *L, |
| 5100 | SwitchInst *Switch, |
| 5101 | BasicBlock *ExitingBlock, |
| 5102 | bool ControlsExit) { |
| 5103 | assert(!L->contains(ExitingBlock) && "Not an exiting block!")((!L->contains(ExitingBlock) && "Not an exiting block!" ) ? static_cast<void> (0) : __assert_fail ("!L->contains(ExitingBlock) && \"Not an exiting block!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 5103, __PRETTY_FUNCTION__)); |
| 5104 | |
| 5105 | // Give up if the exit is the default dest of a switch. |
| 5106 | if (Switch->getDefaultDest() == ExitingBlock) |
| 5107 | return getCouldNotCompute(); |
| 5108 | |
| 5109 | assert(L->contains(Switch->getDefaultDest()) &&((L->contains(Switch->getDefaultDest()) && "Default case must not exit the loop!" ) ? static_cast<void> (0) : __assert_fail ("L->contains(Switch->getDefaultDest()) && \"Default case must not exit the loop!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 5110, __PRETTY_FUNCTION__)) |
| 5110 | "Default case must not exit the loop!")((L->contains(Switch->getDefaultDest()) && "Default case must not exit the loop!" ) ? static_cast<void> (0) : __assert_fail ("L->contains(Switch->getDefaultDest()) && \"Default case must not exit the loop!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 5110, __PRETTY_FUNCTION__)); |
| 5111 | const SCEV *LHS = getSCEVAtScope(Switch->getCondition(), L); |
| 5112 | const SCEV *RHS = getConstant(Switch->findCaseDest(ExitingBlock)); |
| 5113 | |
| 5114 | // while (X != Y) --> while (X-Y != 0) |
| 5115 | ExitLimit EL = HowFarToZero(getMinusSCEV(LHS, RHS), L, ControlsExit); |
| 5116 | if (EL.hasAnyInfo()) |
| 5117 | return EL; |
| 5118 | |
| 5119 | return getCouldNotCompute(); |
| 5120 | } |
| 5121 | |
| 5122 | static ConstantInt * |
| 5123 | EvaluateConstantChrecAtConstant(const SCEVAddRecExpr *AddRec, ConstantInt *C, |
| 5124 | ScalarEvolution &SE) { |
| 5125 | const SCEV *InVal = SE.getConstant(C); |
| 5126 | const SCEV *Val = AddRec->evaluateAtIteration(InVal, SE); |
| 5127 | assert(isa<SCEVConstant>(Val) &&((isa<SCEVConstant>(Val) && "Evaluation of SCEV at constant didn't fold correctly?" ) ? static_cast<void> (0) : __assert_fail ("isa<SCEVConstant>(Val) && \"Evaluation of SCEV at constant didn't fold correctly?\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 5128, __PRETTY_FUNCTION__)) |
| 5128 | "Evaluation of SCEV at constant didn't fold correctly?")((isa<SCEVConstant>(Val) && "Evaluation of SCEV at constant didn't fold correctly?" ) ? static_cast<void> (0) : __assert_fail ("isa<SCEVConstant>(Val) && \"Evaluation of SCEV at constant didn't fold correctly?\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 5128, __PRETTY_FUNCTION__)); |
| 5129 | return cast<SCEVConstant>(Val)->getValue(); |
| 5130 | } |
| 5131 | |
| 5132 | /// ComputeLoadConstantCompareExitLimit - Given an exit condition of |
| 5133 | /// 'icmp op load X, cst', try to see if we can compute the backedge |
| 5134 | /// execution count. |
| 5135 | ScalarEvolution::ExitLimit |
| 5136 | ScalarEvolution::ComputeLoadConstantCompareExitLimit( |
| 5137 | LoadInst *LI, |
| 5138 | Constant *RHS, |
| 5139 | const Loop *L, |
| 5140 | ICmpInst::Predicate predicate) { |
| 5141 | |
| 5142 | if (LI->isVolatile()) return getCouldNotCompute(); |
| 5143 | |
| 5144 | // Check to see if the loaded pointer is a getelementptr of a global. |
| 5145 | // TODO: Use SCEV instead of manually grubbing with GEPs. |
| 5146 | GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(LI->getOperand(0)); |
| 5147 | if (!GEP) return getCouldNotCompute(); |
| 5148 | |
| 5149 | // Make sure that it is really a constant global we are gepping, with an |
| 5150 | // initializer, and make sure the first IDX is really 0. |
| 5151 | GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0)); |
| 5152 | if (!GV || !GV->isConstant() || !GV->hasDefinitiveInitializer() || |
| 5153 | GEP->getNumOperands() < 3 || !isa<Constant>(GEP->getOperand(1)) || |
| 5154 | !cast<Constant>(GEP->getOperand(1))->isNullValue()) |
| 5155 | return getCouldNotCompute(); |
| 5156 | |
| 5157 | // Okay, we allow one non-constant index into the GEP instruction. |
| 5158 | Value *VarIdx = nullptr; |
| 5159 | std::vector<Constant*> Indexes; |
| 5160 | unsigned VarIdxNum = 0; |
| 5161 | for (unsigned i = 2, e = GEP->getNumOperands(); i != e; ++i) |
| 5162 | if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i))) { |
| 5163 | Indexes.push_back(CI); |
| 5164 | } else if (!isa<ConstantInt>(GEP->getOperand(i))) { |
| 5165 | if (VarIdx) return getCouldNotCompute(); // Multiple non-constant idx's. |
| 5166 | VarIdx = GEP->getOperand(i); |
| 5167 | VarIdxNum = i-2; |
| 5168 | Indexes.push_back(nullptr); |
| 5169 | } |
| 5170 | |
| 5171 | // Loop-invariant loads may be a byproduct of loop optimization. Skip them. |
| 5172 | if (!VarIdx) |
| 5173 | return getCouldNotCompute(); |
| 5174 | |
| 5175 | // Okay, we know we have a (load (gep GV, 0, X)) comparison with a constant. |
| 5176 | // Check to see if X is a loop variant variable value now. |
| 5177 | const SCEV *Idx = getSCEV(VarIdx); |
| 5178 | Idx = getSCEVAtScope(Idx, L); |
| 5179 | |
| 5180 | // We can only recognize very limited forms of loop index expressions, in |
| 5181 | // particular, only affine AddRec's like {C1,+,C2}. |
| 5182 | const SCEVAddRecExpr *IdxExpr = dyn_cast<SCEVAddRecExpr>(Idx); |
| 5183 | if (!IdxExpr || !IdxExpr->isAffine() || isLoopInvariant(IdxExpr, L) || |
| 5184 | !isa<SCEVConstant>(IdxExpr->getOperand(0)) || |
| 5185 | !isa<SCEVConstant>(IdxExpr->getOperand(1))) |
| 5186 | return getCouldNotCompute(); |
| 5187 | |
| 5188 | unsigned MaxSteps = MaxBruteForceIterations; |
| 5189 | for (unsigned IterationNum = 0; IterationNum != MaxSteps; ++IterationNum) { |
| 5190 | ConstantInt *ItCst = ConstantInt::get( |
| 5191 | cast<IntegerType>(IdxExpr->getType()), IterationNum); |
| 5192 | ConstantInt *Val = EvaluateConstantChrecAtConstant(IdxExpr, ItCst, *this); |
| 5193 | |
| 5194 | // Form the GEP offset. |
| 5195 | Indexes[VarIdxNum] = Val; |
| 5196 | |
| 5197 | Constant *Result = ConstantFoldLoadThroughGEPIndices(GV->getInitializer(), |
| 5198 | Indexes); |
| 5199 | if (!Result) break; // Cannot compute! |
| 5200 | |
| 5201 | // Evaluate the condition for this iteration. |
| 5202 | Result = ConstantExpr::getICmp(predicate, Result, RHS); |
| 5203 | if (!isa<ConstantInt>(Result)) break; // Couldn't decide for sure |
| 5204 | if (cast<ConstantInt>(Result)->getValue().isMinValue()) { |
| 5205 | #if 0 |
| 5206 | dbgs() << "\n***\n*** Computed loop count " << *ItCst |
| 5207 | << "\n*** From global " << *GV << "*** BB: " << *L->getHeader() |
| 5208 | << "***\n"; |
| 5209 | #endif |
| 5210 | ++NumArrayLenItCounts; |
| 5211 | return getConstant(ItCst); // Found terminating iteration! |
| 5212 | } |
| 5213 | } |
| 5214 | return getCouldNotCompute(); |
| 5215 | } |
| 5216 | |
| 5217 | |
| 5218 | /// CanConstantFold - Return true if we can constant fold an instruction of the |
| 5219 | /// specified type, assuming that all operands were constants. |
| 5220 | static bool CanConstantFold(const Instruction *I) { |
| 5221 | if (isa<BinaryOperator>(I) || isa<CmpInst>(I) || |
| 5222 | isa<SelectInst>(I) || isa<CastInst>(I) || isa<GetElementPtrInst>(I) || |
| 5223 | isa<LoadInst>(I)) |
| 5224 | return true; |
| 5225 | |
| 5226 | if (const CallInst *CI = dyn_cast<CallInst>(I)) |
| 5227 | if (const Function *F = CI->getCalledFunction()) |
| 5228 | return canConstantFoldCallTo(F); |
| 5229 | return false; |
| 5230 | } |
| 5231 | |
| 5232 | /// Determine whether this instruction can constant evolve within this loop |
| 5233 | /// assuming its operands can all constant evolve. |
| 5234 | static bool canConstantEvolve(Instruction *I, const Loop *L) { |
| 5235 | // An instruction outside of the loop can't be derived from a loop PHI. |
| 5236 | if (!L->contains(I)) return false; |
| 5237 | |
| 5238 | if (isa<PHINode>(I)) { |
| 5239 | if (L->getHeader() == I->getParent()) |
| 5240 | return true; |
| 5241 | else |
| 5242 | // We don't currently keep track of the control flow needed to evaluate |
| 5243 | // PHIs, so we cannot handle PHIs inside of loops. |
| 5244 | return false; |
| 5245 | } |
| 5246 | |
| 5247 | // If we won't be able to constant fold this expression even if the operands |
| 5248 | // are constants, bail early. |
| 5249 | return CanConstantFold(I); |
| 5250 | } |
| 5251 | |
| 5252 | /// getConstantEvolvingPHIOperands - Implement getConstantEvolvingPHI by |
| 5253 | /// recursing through each instruction operand until reaching a loop header phi. |
| 5254 | static PHINode * |
| 5255 | getConstantEvolvingPHIOperands(Instruction *UseInst, const Loop *L, |
| 5256 | DenseMap<Instruction *, PHINode *> &PHIMap) { |
| 5257 | |
| 5258 | // Otherwise, we can evaluate this instruction if all of its operands are |
| 5259 | // constant or derived from a PHI node themselves. |
| 5260 | PHINode *PHI = nullptr; |
| 5261 | for (Instruction::op_iterator OpI = UseInst->op_begin(), |
| 5262 | OpE = UseInst->op_end(); OpI != OpE; ++OpI) { |
| 5263 | |
| 5264 | if (isa<Constant>(*OpI)) continue; |
| 5265 | |
| 5266 | Instruction *OpInst = dyn_cast<Instruction>(*OpI); |
| 5267 | if (!OpInst || !canConstantEvolve(OpInst, L)) return nullptr; |
| 5268 | |
| 5269 | PHINode *P = dyn_cast<PHINode>(OpInst); |
| 5270 | if (!P) |
| 5271 | // If this operand is already visited, reuse the prior result. |
| 5272 | // We may have P != PHI if this is the deepest point at which the |
| 5273 | // inconsistent paths meet. |
| 5274 | P = PHIMap.lookup(OpInst); |
| 5275 | if (!P) { |
| 5276 | // Recurse and memoize the results, whether a phi is found or not. |
| 5277 | // This recursive call invalidates pointers into PHIMap. |
| 5278 | P = getConstantEvolvingPHIOperands(OpInst, L, PHIMap); |
| 5279 | PHIMap[OpInst] = P; |
| 5280 | } |
| 5281 | if (!P) |
| 5282 | return nullptr; // Not evolving from PHI |
| 5283 | if (PHI && PHI != P) |
| 5284 | return nullptr; // Evolving from multiple different PHIs. |
| 5285 | PHI = P; |
| 5286 | } |
| 5287 | // This is a expression evolving from a constant PHI! |
| 5288 | return PHI; |
| 5289 | } |
| 5290 | |
| 5291 | /// getConstantEvolvingPHI - Given an LLVM value and a loop, return a PHI node |
| 5292 | /// in the loop that V is derived from. We allow arbitrary operations along the |
| 5293 | /// way, but the operands of an operation must either be constants or a value |
| 5294 | /// derived from a constant PHI. If this expression does not fit with these |
| 5295 | /// constraints, return null. |
| 5296 | static PHINode *getConstantEvolvingPHI(Value *V, const Loop *L) { |
| 5297 | Instruction *I = dyn_cast<Instruction>(V); |
| 5298 | if (!I || !canConstantEvolve(I, L)) return nullptr; |
| 5299 | |
| 5300 | if (PHINode *PN = dyn_cast<PHINode>(I)) { |
| 5301 | return PN; |
| 5302 | } |
| 5303 | |
| 5304 | // Record non-constant instructions contained by the loop. |
| 5305 | DenseMap<Instruction *, PHINode *> PHIMap; |
| 5306 | return getConstantEvolvingPHIOperands(I, L, PHIMap); |
| 5307 | } |
| 5308 | |
| 5309 | /// EvaluateExpression - Given an expression that passes the |
| 5310 | /// getConstantEvolvingPHI predicate, evaluate its value assuming the PHI node |
| 5311 | /// in the loop has the value PHIVal. If we can't fold this expression for some |
| 5312 | /// reason, return null. |
| 5313 | static Constant *EvaluateExpression(Value *V, const Loop *L, |
| 5314 | DenseMap<Instruction *, Constant *> &Vals, |
| 5315 | const DataLayout *DL, |
| 5316 | const TargetLibraryInfo *TLI) { |
| 5317 | // Convenient constant check, but redundant for recursive calls. |
| 5318 | if (Constant *C = dyn_cast<Constant>(V)) return C; |
| 5319 | Instruction *I = dyn_cast<Instruction>(V); |
| 5320 | if (!I) return nullptr; |
| 5321 | |
| 5322 | if (Constant *C = Vals.lookup(I)) return C; |
| 5323 | |
| 5324 | // An instruction inside the loop depends on a value outside the loop that we |
| 5325 | // weren't given a mapping for, or a value such as a call inside the loop. |
| 5326 | if (!canConstantEvolve(I, L)) return nullptr; |
| 5327 | |
| 5328 | // An unmapped PHI can be due to a branch or another loop inside this loop, |
| 5329 | // or due to this not being the initial iteration through a loop where we |
| 5330 | // couldn't compute the evolution of this particular PHI last time. |
| 5331 | if (isa<PHINode>(I)) return nullptr; |
| 5332 | |
| 5333 | std::vector<Constant*> Operands(I->getNumOperands()); |
| 5334 | |
| 5335 | for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) { |
| 5336 | Instruction *Operand = dyn_cast<Instruction>(I->getOperand(i)); |
| 5337 | if (!Operand) { |
| 5338 | Operands[i] = dyn_cast<Constant>(I->getOperand(i)); |
| 5339 | if (!Operands[i]) return nullptr; |
| 5340 | continue; |
| 5341 | } |
| 5342 | Constant *C = EvaluateExpression(Operand, L, Vals, DL, TLI); |
| 5343 | Vals[Operand] = C; |
| 5344 | if (!C) return nullptr; |
| 5345 | Operands[i] = C; |
| 5346 | } |
| 5347 | |
| 5348 | if (CmpInst *CI = dyn_cast<CmpInst>(I)) |
| 5349 | return ConstantFoldCompareInstOperands(CI->getPredicate(), Operands[0], |
| 5350 | Operands[1], DL, TLI); |
| 5351 | if (LoadInst *LI = dyn_cast<LoadInst>(I)) { |
| 5352 | if (!LI->isVolatile()) |
| 5353 | return ConstantFoldLoadFromConstPtr(Operands[0], DL); |
| 5354 | } |
| 5355 | return ConstantFoldInstOperands(I->getOpcode(), I->getType(), Operands, DL, |
| 5356 | TLI); |
| 5357 | } |
| 5358 | |
| 5359 | /// getConstantEvolutionLoopExitValue - If we know that the specified Phi is |
| 5360 | /// in the header of its containing loop, we know the loop executes a |
| 5361 | /// constant number of times, and the PHI node is just a recurrence |
| 5362 | /// involving constants, fold it. |
| 5363 | Constant * |
| 5364 | ScalarEvolution::getConstantEvolutionLoopExitValue(PHINode *PN, |
| 5365 | const APInt &BEs, |
| 5366 | const Loop *L) { |
| 5367 | DenseMap<PHINode*, Constant*>::const_iterator I = |
| 5368 | ConstantEvolutionLoopExitValue.find(PN); |
| 5369 | if (I != ConstantEvolutionLoopExitValue.end()) |
| 5370 | return I->second; |
| 5371 | |
| 5372 | if (BEs.ugt(MaxBruteForceIterations)) |
| 5373 | return ConstantEvolutionLoopExitValue[PN] = nullptr; // Not going to evaluate it. |
| 5374 | |
| 5375 | Constant *&RetVal = ConstantEvolutionLoopExitValue[PN]; |
| 5376 | |
| 5377 | DenseMap<Instruction *, Constant *> CurrentIterVals; |
| 5378 | BasicBlock *Header = L->getHeader(); |
| 5379 | assert(PN->getParent() == Header && "Can't evaluate PHI not in loop header!")((PN->getParent() == Header && "Can't evaluate PHI not in loop header!" ) ? static_cast<void> (0) : __assert_fail ("PN->getParent() == Header && \"Can't evaluate PHI not in loop header!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 5379, __PRETTY_FUNCTION__)); |
| 5380 | |
| 5381 | // Since the loop is canonicalized, the PHI node must have two entries. One |
| 5382 | // entry must be a constant (coming in from outside of the loop), and the |
| 5383 | // second must be derived from the same PHI. |
| 5384 | bool SecondIsBackedge = L->contains(PN->getIncomingBlock(1)); |
| 5385 | PHINode *PHI = nullptr; |
| 5386 | for (BasicBlock::iterator I = Header->begin(); |
| 5387 | (PHI = dyn_cast<PHINode>(I)); ++I) { |
| 5388 | Constant *StartCST = |
| 5389 | dyn_cast<Constant>(PHI->getIncomingValue(!SecondIsBackedge)); |
| 5390 | if (!StartCST) continue; |
| 5391 | CurrentIterVals[PHI] = StartCST; |
| 5392 | } |
| 5393 | if (!CurrentIterVals.count(PN)) |
| 5394 | return RetVal = nullptr; |
| 5395 | |
| 5396 | Value *BEValue = PN->getIncomingValue(SecondIsBackedge); |
| 5397 | |
| 5398 | // Execute the loop symbolically to determine the exit value. |
| 5399 | if (BEs.getActiveBits() >= 32) |
| 5400 | return RetVal = nullptr; // More than 2^32-1 iterations?? Not doing it! |
| 5401 | |
| 5402 | unsigned NumIterations = BEs.getZExtValue(); // must be in range |
| 5403 | unsigned IterationNum = 0; |
| 5404 | for (; ; ++IterationNum) { |
| 5405 | if (IterationNum == NumIterations) |
| 5406 | return RetVal = CurrentIterVals[PN]; // Got exit value! |
| 5407 | |
| 5408 | // Compute the value of the PHIs for the next iteration. |
| 5409 | // EvaluateExpression adds non-phi values to the CurrentIterVals map. |
| 5410 | DenseMap<Instruction *, Constant *> NextIterVals; |
| 5411 | Constant *NextPHI = EvaluateExpression(BEValue, L, CurrentIterVals, DL, |
| 5412 | TLI); |
| 5413 | if (!NextPHI) |
| 5414 | return nullptr; // Couldn't evaluate! |
| 5415 | NextIterVals[PN] = NextPHI; |
| 5416 | |
| 5417 | bool StoppedEvolving = NextPHI == CurrentIterVals[PN]; |
| 5418 | |
| 5419 | // Also evaluate the other PHI nodes. However, we don't get to stop if we |
| 5420 | // cease to be able to evaluate one of them or if they stop evolving, |
| 5421 | // because that doesn't necessarily prevent us from computing PN. |
| 5422 | SmallVector<std::pair<PHINode *, Constant *>, 8> PHIsToCompute; |
| 5423 | for (DenseMap<Instruction *, Constant *>::const_iterator |
| 5424 | I = CurrentIterVals.begin(), E = CurrentIterVals.end(); I != E; ++I){ |
| 5425 | PHINode *PHI = dyn_cast<PHINode>(I->first); |
| 5426 | if (!PHI || PHI == PN || PHI->getParent() != Header) continue; |
| 5427 | PHIsToCompute.push_back(std::make_pair(PHI, I->second)); |
| 5428 | } |
| 5429 | // We use two distinct loops because EvaluateExpression may invalidate any |
| 5430 | // iterators into CurrentIterVals. |
| 5431 | for (SmallVectorImpl<std::pair<PHINode *, Constant*> >::const_iterator |
| 5432 | I = PHIsToCompute.begin(), E = PHIsToCompute.end(); I != E; ++I) { |
| 5433 | PHINode *PHI = I->first; |
| 5434 | Constant *&NextPHI = NextIterVals[PHI]; |
| 5435 | if (!NextPHI) { // Not already computed. |
| 5436 | Value *BEValue = PHI->getIncomingValue(SecondIsBackedge); |
| 5437 | NextPHI = EvaluateExpression(BEValue, L, CurrentIterVals, DL, TLI); |
| 5438 | } |
| 5439 | if (NextPHI != I->second) |
| 5440 | StoppedEvolving = false; |
| 5441 | } |
| 5442 | |
| 5443 | // If all entries in CurrentIterVals == NextIterVals then we can stop |
| 5444 | // iterating, the loop can't continue to change. |
| 5445 | if (StoppedEvolving) |
| 5446 | return RetVal = CurrentIterVals[PN]; |
| 5447 | |
| 5448 | CurrentIterVals.swap(NextIterVals); |
| 5449 | } |
| 5450 | } |
| 5451 | |
| 5452 | /// ComputeExitCountExhaustively - If the loop is known to execute a |
| 5453 | /// constant number of times (the condition evolves only from constants), |
| 5454 | /// try to evaluate a few iterations of the loop until we get the exit |
| 5455 | /// condition gets a value of ExitWhen (true or false). If we cannot |
| 5456 | /// evaluate the trip count of the loop, return getCouldNotCompute(). |
| 5457 | const SCEV *ScalarEvolution::ComputeExitCountExhaustively(const Loop *L, |
| 5458 | Value *Cond, |
| 5459 | bool ExitWhen) { |
| 5460 | PHINode *PN = getConstantEvolvingPHI(Cond, L); |
| 5461 | if (!PN) return getCouldNotCompute(); |
| 5462 | |
| 5463 | // If the loop is canonicalized, the PHI will have exactly two entries. |
| 5464 | // That's the only form we support here. |
| 5465 | if (PN->getNumIncomingValues() != 2) return getCouldNotCompute(); |
| 5466 | |
| 5467 | DenseMap<Instruction *, Constant *> CurrentIterVals; |
| 5468 | BasicBlock *Header = L->getHeader(); |
| 5469 | assert(PN->getParent() == Header && "Can't evaluate PHI not in loop header!")((PN->getParent() == Header && "Can't evaluate PHI not in loop header!" ) ? static_cast<void> (0) : __assert_fail ("PN->getParent() == Header && \"Can't evaluate PHI not in loop header!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 5469, __PRETTY_FUNCTION__)); |
| 5470 | |
| 5471 | // One entry must be a constant (coming in from outside of the loop), and the |
| 5472 | // second must be derived from the same PHI. |
| 5473 | bool SecondIsBackedge = L->contains(PN->getIncomingBlock(1)); |
| 5474 | PHINode *PHI = nullptr; |
| 5475 | for (BasicBlock::iterator I = Header->begin(); |
| 5476 | (PHI = dyn_cast<PHINode>(I)); ++I) { |
| 5477 | Constant *StartCST = |
| 5478 | dyn_cast<Constant>(PHI->getIncomingValue(!SecondIsBackedge)); |
| 5479 | if (!StartCST) continue; |
| 5480 | CurrentIterVals[PHI] = StartCST; |
| 5481 | } |
| 5482 | if (!CurrentIterVals.count(PN)) |
| 5483 | return getCouldNotCompute(); |
| 5484 | |
| 5485 | // Okay, we find a PHI node that defines the trip count of this loop. Execute |
| 5486 | // the loop symbolically to determine when the condition gets a value of |
| 5487 | // "ExitWhen". |
| 5488 | |
| 5489 | unsigned MaxIterations = MaxBruteForceIterations; // Limit analysis. |
| 5490 | for (unsigned IterationNum = 0; IterationNum != MaxIterations;++IterationNum){ |
| 5491 | ConstantInt *CondVal = |
| 5492 | dyn_cast_or_null<ConstantInt>(EvaluateExpression(Cond, L, CurrentIterVals, |
| 5493 | DL, TLI)); |
| 5494 | |
| 5495 | // Couldn't symbolically evaluate. |
| 5496 | if (!CondVal) return getCouldNotCompute(); |
| 5497 | |
| 5498 | if (CondVal->getValue() == uint64_t(ExitWhen)) { |
| 5499 | ++NumBruteForceTripCountsComputed; |
| 5500 | return getConstant(Type::getInt32Ty(getContext()), IterationNum); |
| 5501 | } |
| 5502 | |
| 5503 | // Update all the PHI nodes for the next iteration. |
| 5504 | DenseMap<Instruction *, Constant *> NextIterVals; |
| 5505 | |
| 5506 | // Create a list of which PHIs we need to compute. We want to do this before |
| 5507 | // calling EvaluateExpression on them because that may invalidate iterators |
| 5508 | // into CurrentIterVals. |
| 5509 | SmallVector<PHINode *, 8> PHIsToCompute; |
| 5510 | for (DenseMap<Instruction *, Constant *>::const_iterator |
| 5511 | I = CurrentIterVals.begin(), E = CurrentIterVals.end(); I != E; ++I){ |
| 5512 | PHINode *PHI = dyn_cast<PHINode>(I->first); |
| 5513 | if (!PHI || PHI->getParent() != Header) continue; |
| 5514 | PHIsToCompute.push_back(PHI); |
| 5515 | } |
| 5516 | for (SmallVectorImpl<PHINode *>::const_iterator I = PHIsToCompute.begin(), |
| 5517 | E = PHIsToCompute.end(); I != E; ++I) { |
| 5518 | PHINode *PHI = *I; |
| 5519 | Constant *&NextPHI = NextIterVals[PHI]; |
| 5520 | if (NextPHI) continue; // Already computed! |
| 5521 | |
| 5522 | Value *BEValue = PHI->getIncomingValue(SecondIsBackedge); |
| 5523 | NextPHI = EvaluateExpression(BEValue, L, CurrentIterVals, DL, TLI); |
| 5524 | } |
| 5525 | CurrentIterVals.swap(NextIterVals); |
| 5526 | } |
| 5527 | |
| 5528 | // Too many iterations were needed to evaluate. |
| 5529 | return getCouldNotCompute(); |
| 5530 | } |
| 5531 | |
| 5532 | /// getSCEVAtScope - Return a SCEV expression for the specified value |
| 5533 | /// at the specified scope in the program. The L value specifies a loop |
| 5534 | /// nest to evaluate the expression at, where null is the top-level or a |
| 5535 | /// specified loop is immediately inside of the loop. |
| 5536 | /// |
| 5537 | /// This method can be used to compute the exit value for a variable defined |
| 5538 | /// in a loop by querying what the value will hold in the parent loop. |
| 5539 | /// |
| 5540 | /// In the case that a relevant loop exit value cannot be computed, the |
| 5541 | /// original value V is returned. |
| 5542 | const SCEV *ScalarEvolution::getSCEVAtScope(const SCEV *V, const Loop *L) { |
| 5543 | // Check to see if we've folded this expression at this loop before. |
| 5544 | SmallVector<std::pair<const Loop *, const SCEV *>, 2> &Values = ValuesAtScopes[V]; |
| 5545 | for (unsigned u = 0; u < Values.size(); u++) { |
| 5546 | if (Values[u].first == L) |
| 5547 | return Values[u].second ? Values[u].second : V; |
| 5548 | } |
| 5549 | Values.push_back(std::make_pair(L, static_cast<const SCEV *>(nullptr))); |
| 5550 | // Otherwise compute it. |
| 5551 | const SCEV *C = computeSCEVAtScope(V, L); |
| 5552 | SmallVector<std::pair<const Loop *, const SCEV *>, 2> &Values2 = ValuesAtScopes[V]; |
| 5553 | for (unsigned u = Values2.size(); u > 0; u--) { |
| 5554 | if (Values2[u - 1].first == L) { |
| 5555 | Values2[u - 1].second = C; |
| 5556 | break; |
| 5557 | } |
| 5558 | } |
| 5559 | return C; |
| 5560 | } |
| 5561 | |
| 5562 | /// This builds up a Constant using the ConstantExpr interface. That way, we |
| 5563 | /// will return Constants for objects which aren't represented by a |
| 5564 | /// SCEVConstant, because SCEVConstant is restricted to ConstantInt. |
| 5565 | /// Returns NULL if the SCEV isn't representable as a Constant. |
| 5566 | static Constant *BuildConstantFromSCEV(const SCEV *V) { |
| 5567 | switch (static_cast<SCEVTypes>(V->getSCEVType())) { |
| 5568 | case scCouldNotCompute: |
| 5569 | case scAddRecExpr: |
| 5570 | break; |
| 5571 | case scConstant: |
| 5572 | return cast<SCEVConstant>(V)->getValue(); |
| 5573 | case scUnknown: |
| 5574 | return dyn_cast<Constant>(cast<SCEVUnknown>(V)->getValue()); |
| 5575 | case scSignExtend: { |
| 5576 | const SCEVSignExtendExpr *SS = cast<SCEVSignExtendExpr>(V); |
| 5577 | if (Constant *CastOp = BuildConstantFromSCEV(SS->getOperand())) |
| 5578 | return ConstantExpr::getSExt(CastOp, SS->getType()); |
| 5579 | break; |
| 5580 | } |
| 5581 | case scZeroExtend: { |
| 5582 | const SCEVZeroExtendExpr *SZ = cast<SCEVZeroExtendExpr>(V); |
| 5583 | if (Constant *CastOp = BuildConstantFromSCEV(SZ->getOperand())) |
| 5584 | return ConstantExpr::getZExt(CastOp, SZ->getType()); |
| 5585 | break; |
| 5586 | } |
| 5587 | case scTruncate: { |
| 5588 | const SCEVTruncateExpr *ST = cast<SCEVTruncateExpr>(V); |
| 5589 | if (Constant *CastOp = BuildConstantFromSCEV(ST->getOperand())) |
| 5590 | return ConstantExpr::getTrunc(CastOp, ST->getType()); |
| 5591 | break; |
| 5592 | } |
| 5593 | case scAddExpr: { |
| 5594 | const SCEVAddExpr *SA = cast<SCEVAddExpr>(V); |
| 5595 | if (Constant *C = BuildConstantFromSCEV(SA->getOperand(0))) { |
| 5596 | if (PointerType *PTy = dyn_cast<PointerType>(C->getType())) { |
| 5597 | unsigned AS = PTy->getAddressSpace(); |
| 5598 | Type *DestPtrTy = Type::getInt8PtrTy(C->getContext(), AS); |
| 5599 | C = ConstantExpr::getBitCast(C, DestPtrTy); |
| 5600 | } |
| 5601 | for (unsigned i = 1, e = SA->getNumOperands(); i != e; ++i) { |
| 5602 | Constant *C2 = BuildConstantFromSCEV(SA->getOperand(i)); |
| 5603 | if (!C2) return nullptr; |
| 5604 | |
| 5605 | // First pointer! |
| 5606 | if (!C->getType()->isPointerTy() && C2->getType()->isPointerTy()) { |
| 5607 | unsigned AS = C2->getType()->getPointerAddressSpace(); |
| 5608 | std::swap(C, C2); |
| 5609 | Type *DestPtrTy = Type::getInt8PtrTy(C->getContext(), AS); |
| 5610 | // The offsets have been converted to bytes. We can add bytes to an |
| 5611 | // i8* by GEP with the byte count in the first index. |
| 5612 | C = ConstantExpr::getBitCast(C, DestPtrTy); |
| 5613 | } |
| 5614 | |
| 5615 | // Don't bother trying to sum two pointers. We probably can't |
| 5616 | // statically compute a load that results from it anyway. |
| 5617 | if (C2->getType()->isPointerTy()) |
| 5618 | return nullptr; |
| 5619 | |
| 5620 | if (PointerType *PTy = dyn_cast<PointerType>(C->getType())) { |
| 5621 | if (PTy->getElementType()->isStructTy()) |
| 5622 | C2 = ConstantExpr::getIntegerCast( |
| 5623 | C2, Type::getInt32Ty(C->getContext()), true); |
| 5624 | C = ConstantExpr::getGetElementPtr(C, C2); |
| 5625 | } else |
| 5626 | C = ConstantExpr::getAdd(C, C2); |
| 5627 | } |
| 5628 | return C; |
| 5629 | } |
| 5630 | break; |
| 5631 | } |
| 5632 | case scMulExpr: { |
| 5633 | const SCEVMulExpr *SM = cast<SCEVMulExpr>(V); |
| 5634 | if (Constant *C = BuildConstantFromSCEV(SM->getOperand(0))) { |
| 5635 | // Don't bother with pointers at all. |
| 5636 | if (C->getType()->isPointerTy()) return nullptr; |
| 5637 | for (unsigned i = 1, e = SM->getNumOperands(); i != e; ++i) { |
| 5638 | Constant *C2 = BuildConstantFromSCEV(SM->getOperand(i)); |
| 5639 | if (!C2 || C2->getType()->isPointerTy()) return nullptr; |
| 5640 | C = ConstantExpr::getMul(C, C2); |
| 5641 | } |
| 5642 | return C; |
| 5643 | } |
| 5644 | break; |
| 5645 | } |
| 5646 | case scUDivExpr: { |
| 5647 | const SCEVUDivExpr *SU = cast<SCEVUDivExpr>(V); |
| 5648 | if (Constant *LHS = BuildConstantFromSCEV(SU->getLHS())) |
| 5649 | if (Constant *RHS = BuildConstantFromSCEV(SU->getRHS())) |
| 5650 | if (LHS->getType() == RHS->getType()) |
| 5651 | return ConstantExpr::getUDiv(LHS, RHS); |
| 5652 | break; |
| 5653 | } |
| 5654 | case scSMaxExpr: |
| 5655 | case scUMaxExpr: |
| 5656 | break; // TODO: smax, umax. |
| 5657 | } |
| 5658 | return nullptr; |
| 5659 | } |
| 5660 | |
| 5661 | const SCEV *ScalarEvolution::computeSCEVAtScope(const SCEV *V, const Loop *L) { |
| 5662 | if (isa<SCEVConstant>(V)) return V; |
| 5663 | |
| 5664 | // If this instruction is evolved from a constant-evolving PHI, compute the |
| 5665 | // exit value from the loop without using SCEVs. |
| 5666 | if (const SCEVUnknown *SU = dyn_cast<SCEVUnknown>(V)) { |
| 5667 | if (Instruction *I = dyn_cast<Instruction>(SU->getValue())) { |
| 5668 | const Loop *LI = (*this->LI)[I->getParent()]; |
| 5669 | if (LI && LI->getParentLoop() == L) // Looking for loop exit value. |
| 5670 | if (PHINode *PN = dyn_cast<PHINode>(I)) |
| 5671 | if (PN->getParent() == LI->getHeader()) { |
| 5672 | // Okay, there is no closed form solution for the PHI node. Check |
| 5673 | // to see if the loop that contains it has a known backedge-taken |
| 5674 | // count. If so, we may be able to force computation of the exit |
| 5675 | // value. |
| 5676 | const SCEV *BackedgeTakenCount = getBackedgeTakenCount(LI); |
| 5677 | if (const SCEVConstant *BTCC = |
| 5678 | dyn_cast<SCEVConstant>(BackedgeTakenCount)) { |
| 5679 | // Okay, we know how many times the containing loop executes. If |
| 5680 | // this is a constant evolving PHI node, get the final value at |
| 5681 | // the specified iteration number. |
| 5682 | Constant *RV = getConstantEvolutionLoopExitValue(PN, |
| 5683 | BTCC->getValue()->getValue(), |
| 5684 | LI); |
| 5685 | if (RV) return getSCEV(RV); |
| 5686 | } |
| 5687 | } |
| 5688 | |
| 5689 | // Okay, this is an expression that we cannot symbolically evaluate |
| 5690 | // into a SCEV. Check to see if it's possible to symbolically evaluate |
| 5691 | // the arguments into constants, and if so, try to constant propagate the |
| 5692 | // result. This is particularly useful for computing loop exit values. |
| 5693 | if (CanConstantFold(I)) { |
| 5694 | SmallVector<Constant *, 4> Operands; |
| 5695 | bool MadeImprovement = false; |
| 5696 | for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) { |
| 5697 | Value *Op = I->getOperand(i); |
| 5698 | if (Constant *C = dyn_cast<Constant>(Op)) { |
| 5699 | Operands.push_back(C); |
| 5700 | continue; |
| 5701 | } |
| 5702 | |
| 5703 | // If any of the operands is non-constant and if they are |
| 5704 | // non-integer and non-pointer, don't even try to analyze them |
| 5705 | // with scev techniques. |
| 5706 | if (!isSCEVable(Op->getType())) |
| 5707 | return V; |
| 5708 | |
| 5709 | const SCEV *OrigV = getSCEV(Op); |
| 5710 | const SCEV *OpV = getSCEVAtScope(OrigV, L); |
| 5711 | MadeImprovement |= OrigV != OpV; |
| 5712 | |
| 5713 | Constant *C = BuildConstantFromSCEV(OpV); |
| 5714 | if (!C) return V; |
| 5715 | if (C->getType() != Op->getType()) |
| 5716 | C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false, |
| 5717 | Op->getType(), |
| 5718 | false), |
| 5719 | C, Op->getType()); |
| 5720 | Operands.push_back(C); |
| 5721 | } |
| 5722 | |
| 5723 | // Check to see if getSCEVAtScope actually made an improvement. |
| 5724 | if (MadeImprovement) { |
| 5725 | Constant *C = nullptr; |
| 5726 | if (const CmpInst *CI = dyn_cast<CmpInst>(I)) |
| 5727 | C = ConstantFoldCompareInstOperands(CI->getPredicate(), |
| 5728 | Operands[0], Operands[1], DL, |
| 5729 | TLI); |
| 5730 | else if (const LoadInst *LI = dyn_cast<LoadInst>(I)) { |
| 5731 | if (!LI->isVolatile()) |
| 5732 | C = ConstantFoldLoadFromConstPtr(Operands[0], DL); |
| 5733 | } else |
| 5734 | C = ConstantFoldInstOperands(I->getOpcode(), I->getType(), |
| 5735 | Operands, DL, TLI); |
| 5736 | if (!C) return V; |
| 5737 | return getSCEV(C); |
| 5738 | } |
| 5739 | } |
| 5740 | } |
| 5741 | |
| 5742 | // This is some other type of SCEVUnknown, just return it. |
| 5743 | return V; |
| 5744 | } |
| 5745 | |
| 5746 | if (const SCEVCommutativeExpr *Comm = dyn_cast<SCEVCommutativeExpr>(V)) { |
| 5747 | // Avoid performing the look-up in the common case where the specified |
| 5748 | // expression has no loop-variant portions. |
| 5749 | for (unsigned i = 0, e = Comm->getNumOperands(); i != e; ++i) { |
| 5750 | const SCEV *OpAtScope = getSCEVAtScope(Comm->getOperand(i), L); |
| 5751 | if (OpAtScope != Comm->getOperand(i)) { |
| 5752 | // Okay, at least one of these operands is loop variant but might be |
| 5753 | // foldable. Build a new instance of the folded commutative expression. |
| 5754 | SmallVector<const SCEV *, 8> NewOps(Comm->op_begin(), |
| 5755 | Comm->op_begin()+i); |
| 5756 | NewOps.push_back(OpAtScope); |
| 5757 | |
| 5758 | for (++i; i != e; ++i) { |
| 5759 | OpAtScope = getSCEVAtScope(Comm->getOperand(i), L); |
| 5760 | NewOps.push_back(OpAtScope); |
| 5761 | } |
| 5762 | if (isa<SCEVAddExpr>(Comm)) |
| 5763 | return getAddExpr(NewOps); |
| 5764 | if (isa<SCEVMulExpr>(Comm)) |
| 5765 | return getMulExpr(NewOps); |
| 5766 | if (isa<SCEVSMaxExpr>(Comm)) |
| 5767 | return getSMaxExpr(NewOps); |
| 5768 | if (isa<SCEVUMaxExpr>(Comm)) |
| 5769 | return getUMaxExpr(NewOps); |
| 5770 | llvm_unreachable("Unknown commutative SCEV type!")::llvm::llvm_unreachable_internal("Unknown commutative SCEV type!" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 5770); |
| 5771 | } |
| 5772 | } |
| 5773 | // If we got here, all operands are loop invariant. |
| 5774 | return Comm; |
| 5775 | } |
| 5776 | |
| 5777 | if (const SCEVUDivExpr *Div = dyn_cast<SCEVUDivExpr>(V)) { |
| 5778 | const SCEV *LHS = getSCEVAtScope(Div->getLHS(), L); |
| 5779 | const SCEV *RHS = getSCEVAtScope(Div->getRHS(), L); |
| 5780 | if (LHS == Div->getLHS() && RHS == Div->getRHS()) |
| 5781 | return Div; // must be loop invariant |
| 5782 | return getUDivExpr(LHS, RHS); |
| 5783 | } |
| 5784 | |
| 5785 | // If this is a loop recurrence for a loop that does not contain L, then we |
| 5786 | // are dealing with the final value computed by the loop. |
| 5787 | if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(V)) { |
| 5788 | // First, attempt to evaluate each operand. |
| 5789 | // Avoid performing the look-up in the common case where the specified |
| 5790 | // expression has no loop-variant portions. |
| 5791 | for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i) { |
| 5792 | const SCEV *OpAtScope = getSCEVAtScope(AddRec->getOperand(i), L); |
| 5793 | if (OpAtScope == AddRec->getOperand(i)) |
| 5794 | continue; |
| 5795 | |
| 5796 | // Okay, at least one of these operands is loop variant but might be |
| 5797 | // foldable. Build a new instance of the folded commutative expression. |
| 5798 | SmallVector<const SCEV *, 8> NewOps(AddRec->op_begin(), |
| 5799 | AddRec->op_begin()+i); |
| 5800 | NewOps.push_back(OpAtScope); |
| 5801 | for (++i; i != e; ++i) |
| 5802 | NewOps.push_back(getSCEVAtScope(AddRec->getOperand(i), L)); |
| 5803 | |
| 5804 | const SCEV *FoldedRec = |
| 5805 | getAddRecExpr(NewOps, AddRec->getLoop(), |
| 5806 | AddRec->getNoWrapFlags(SCEV::FlagNW)); |
| 5807 | AddRec = dyn_cast<SCEVAddRecExpr>(FoldedRec); |
| 5808 | // The addrec may be folded to a nonrecurrence, for example, if the |
| 5809 | // induction variable is multiplied by zero after constant folding. Go |
| 5810 | // ahead and return the folded value. |
| 5811 | if (!AddRec) |
| 5812 | return FoldedRec; |
| 5813 | break; |
| 5814 | } |
| 5815 | |
| 5816 | // If the scope is outside the addrec's loop, evaluate it by using the |
| 5817 | // loop exit value of the addrec. |
| 5818 | if (!AddRec->getLoop()->contains(L)) { |
| 5819 | // To evaluate this recurrence, we need to know how many times the AddRec |
| 5820 | // loop iterates. Compute this now. |
| 5821 | const SCEV *BackedgeTakenCount = getBackedgeTakenCount(AddRec->getLoop()); |
| 5822 | if (BackedgeTakenCount == getCouldNotCompute()) return AddRec; |
| 5823 | |
| 5824 | // Then, evaluate the AddRec. |
| 5825 | return AddRec->evaluateAtIteration(BackedgeTakenCount, *this); |
| 5826 | } |
| 5827 | |
| 5828 | return AddRec; |
| 5829 | } |
| 5830 | |
| 5831 | if (const SCEVZeroExtendExpr *Cast = dyn_cast<SCEVZeroExtendExpr>(V)) { |
| 5832 | const SCEV *Op = getSCEVAtScope(Cast->getOperand(), L); |
| 5833 | if (Op == Cast->getOperand()) |
| 5834 | return Cast; // must be loop invariant |
| 5835 | return getZeroExtendExpr(Op, Cast->getType()); |
| 5836 | } |
| 5837 | |
| 5838 | if (const SCEVSignExtendExpr *Cast = dyn_cast<SCEVSignExtendExpr>(V)) { |
| 5839 | const SCEV *Op = getSCEVAtScope(Cast->getOperand(), L); |
| 5840 | if (Op == Cast->getOperand()) |
| 5841 | return Cast; // must be loop invariant |
| 5842 | return getSignExtendExpr(Op, Cast->getType()); |
| 5843 | } |
| 5844 | |
| 5845 | if (const SCEVTruncateExpr *Cast = dyn_cast<SCEVTruncateExpr>(V)) { |
| 5846 | const SCEV *Op = getSCEVAtScope(Cast->getOperand(), L); |
| 5847 | if (Op == Cast->getOperand()) |
| 5848 | return Cast; // must be loop invariant |
| 5849 | return getTruncateExpr(Op, Cast->getType()); |
| 5850 | } |
| 5851 | |
| 5852 | llvm_unreachable("Unknown SCEV type!")::llvm::llvm_unreachable_internal("Unknown SCEV type!", "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 5852); |
| 5853 | } |
| 5854 | |
| 5855 | /// getSCEVAtScope - This is a convenience function which does |
| 5856 | /// getSCEVAtScope(getSCEV(V), L). |
| 5857 | const SCEV *ScalarEvolution::getSCEVAtScope(Value *V, const Loop *L) { |
| 5858 | return getSCEVAtScope(getSCEV(V), L); |
| 5859 | } |
| 5860 | |
| 5861 | /// SolveLinEquationWithOverflow - Finds the minimum unsigned root of the |
| 5862 | /// following equation: |
| 5863 | /// |
| 5864 | /// A * X = B (mod N) |
| 5865 | /// |
| 5866 | /// where N = 2^BW and BW is the common bit width of A and B. The signedness of |
| 5867 | /// A and B isn't important. |
| 5868 | /// |
| 5869 | /// If the equation does not have a solution, SCEVCouldNotCompute is returned. |
| 5870 | static const SCEV *SolveLinEquationWithOverflow(const APInt &A, const APInt &B, |
| 5871 | ScalarEvolution &SE) { |
| 5872 | uint32_t BW = A.getBitWidth(); |
| 5873 | assert(BW == B.getBitWidth() && "Bit widths must be the same.")((BW == B.getBitWidth() && "Bit widths must be the same." ) ? static_cast<void> (0) : __assert_fail ("BW == B.getBitWidth() && \"Bit widths must be the same.\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 5873, __PRETTY_FUNCTION__)); |
| 5874 | assert(A != 0 && "A must be non-zero.")((A != 0 && "A must be non-zero.") ? static_cast<void > (0) : __assert_fail ("A != 0 && \"A must be non-zero.\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 5874, __PRETTY_FUNCTION__)); |
| 5875 | |
| 5876 | // 1. D = gcd(A, N) |
| 5877 | // |
| 5878 | // The gcd of A and N may have only one prime factor: 2. The number of |
| 5879 | // trailing zeros in A is its multiplicity |
| 5880 | uint32_t Mult2 = A.countTrailingZeros(); |
| 5881 | // D = 2^Mult2 |
| 5882 | |
| 5883 | // 2. Check if B is divisible by D. |
| 5884 | // |
| 5885 | // B is divisible by D if and only if the multiplicity of prime factor 2 for B |
| 5886 | // is not less than multiplicity of this prime factor for D. |
| 5887 | if (B.countTrailingZeros() < Mult2) |
| 5888 | return SE.getCouldNotCompute(); |
| 5889 | |
| 5890 | // 3. Compute I: the multiplicative inverse of (A / D) in arithmetic |
| 5891 | // modulo (N / D). |
| 5892 | // |
| 5893 | // (N / D) may need BW+1 bits in its representation. Hence, we'll use this |
| 5894 | // bit width during computations. |
| 5895 | APInt AD = A.lshr(Mult2).zext(BW + 1); // AD = A / D |
| 5896 | APInt Mod(BW + 1, 0); |
| 5897 | Mod.setBit(BW - Mult2); // Mod = N / D |
| 5898 | APInt I = AD.multiplicativeInverse(Mod); |
| 5899 | |
| 5900 | // 4. Compute the minimum unsigned root of the equation: |
| 5901 | // I * (B / D) mod (N / D) |
| 5902 | APInt Result = (I * B.lshr(Mult2).zext(BW + 1)).urem(Mod); |
| 5903 | |
| 5904 | // The result is guaranteed to be less than 2^BW so we may truncate it to BW |
| 5905 | // bits. |
| 5906 | return SE.getConstant(Result.trunc(BW)); |
| 5907 | } |
| 5908 | |
| 5909 | /// SolveQuadraticEquation - Find the roots of the quadratic equation for the |
| 5910 | /// given quadratic chrec {L,+,M,+,N}. This returns either the two roots (which |
| 5911 | /// might be the same) or two SCEVCouldNotCompute objects. |
| 5912 | /// |
| 5913 | static std::pair<const SCEV *,const SCEV *> |
| 5914 | SolveQuadraticEquation(const SCEVAddRecExpr *AddRec, ScalarEvolution &SE) { |
| 5915 | assert(AddRec->getNumOperands() == 3 && "This is not a quadratic chrec!")((AddRec->getNumOperands() == 3 && "This is not a quadratic chrec!" ) ? static_cast<void> (0) : __assert_fail ("AddRec->getNumOperands() == 3 && \"This is not a quadratic chrec!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 5915, __PRETTY_FUNCTION__)); |
| 5916 | const SCEVConstant *LC = dyn_cast<SCEVConstant>(AddRec->getOperand(0)); |
| 5917 | const SCEVConstant *MC = dyn_cast<SCEVConstant>(AddRec->getOperand(1)); |
| 5918 | const SCEVConstant *NC = dyn_cast<SCEVConstant>(AddRec->getOperand(2)); |
| 5919 | |
| 5920 | // We currently can only solve this if the coefficients are constants. |
| 5921 | if (!LC || !MC || !NC) { |
| 5922 | const SCEV *CNC = SE.getCouldNotCompute(); |
| 5923 | return std::make_pair(CNC, CNC); |
| 5924 | } |
| 5925 | |
| 5926 | uint32_t BitWidth = LC->getValue()->getValue().getBitWidth(); |
| 5927 | const APInt &L = LC->getValue()->getValue(); |
| 5928 | const APInt &M = MC->getValue()->getValue(); |
| 5929 | const APInt &N = NC->getValue()->getValue(); |
| 5930 | APInt Two(BitWidth, 2); |
| 5931 | APInt Four(BitWidth, 4); |
| 5932 | |
| 5933 | { |
| 5934 | using namespace APIntOps; |
| 5935 | const APInt& C = L; |
| 5936 | // Convert from chrec coefficients to polynomial coefficients AX^2+BX+C |
| 5937 | // The B coefficient is M-N/2 |
| 5938 | APInt B(M); |
| 5939 | B -= sdiv(N,Two); |
| 5940 | |
| 5941 | // The A coefficient is N/2 |
| 5942 | APInt A(N.sdiv(Two)); |
| 5943 | |
| 5944 | // Compute the B^2-4ac term. |
| 5945 | APInt SqrtTerm(B); |
| 5946 | SqrtTerm *= B; |
| 5947 | SqrtTerm -= Four * (A * C); |
| 5948 | |
| 5949 | if (SqrtTerm.isNegative()) { |
| 5950 | // The loop is provably infinite. |
| 5951 | const SCEV *CNC = SE.getCouldNotCompute(); |
| 5952 | return std::make_pair(CNC, CNC); |
| 5953 | } |
| 5954 | |
| 5955 | // Compute sqrt(B^2-4ac). This is guaranteed to be the nearest |
| 5956 | // integer value or else APInt::sqrt() will assert. |
| 5957 | APInt SqrtVal(SqrtTerm.sqrt()); |
| 5958 | |
| 5959 | // Compute the two solutions for the quadratic formula. |
| 5960 | // The divisions must be performed as signed divisions. |
| 5961 | APInt NegB(-B); |
| 5962 | APInt TwoA(A << 1); |
| 5963 | if (TwoA.isMinValue()) { |
| 5964 | const SCEV *CNC = SE.getCouldNotCompute(); |
| 5965 | return std::make_pair(CNC, CNC); |
| 5966 | } |
| 5967 | |
| 5968 | LLVMContext &Context = SE.getContext(); |
| 5969 | |
| 5970 | ConstantInt *Solution1 = |
| 5971 | ConstantInt::get(Context, (NegB + SqrtVal).sdiv(TwoA)); |
| 5972 | ConstantInt *Solution2 = |
| 5973 | ConstantInt::get(Context, (NegB - SqrtVal).sdiv(TwoA)); |
| 5974 | |
| 5975 | return std::make_pair(SE.getConstant(Solution1), |
| 5976 | SE.getConstant(Solution2)); |
| 5977 | } // end APIntOps namespace |
| 5978 | } |
| 5979 | |
| 5980 | /// HowFarToZero - Return the number of times a backedge comparing the specified |
| 5981 | /// value to zero will execute. If not computable, return CouldNotCompute. |
| 5982 | /// |
| 5983 | /// This is only used for loops with a "x != y" exit test. The exit condition is |
| 5984 | /// now expressed as a single expression, V = x-y. So the exit test is |
| 5985 | /// effectively V != 0. We know and take advantage of the fact that this |
| 5986 | /// expression only being used in a comparison by zero context. |
| 5987 | ScalarEvolution::ExitLimit |
| 5988 | ScalarEvolution::HowFarToZero(const SCEV *V, const Loop *L, bool ControlsExit) { |
| 5989 | // If the value is a constant |
| 5990 | if (const SCEVConstant *C = dyn_cast<SCEVConstant>(V)) { |
| 5991 | // If the value is already zero, the branch will execute zero times. |
| 5992 | if (C->getValue()->isZero()) return C; |
| 5993 | return getCouldNotCompute(); // Otherwise it will loop infinitely. |
| 5994 | } |
| 5995 | |
| 5996 | const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(V); |
| 5997 | if (!AddRec || AddRec->getLoop() != L) |
| 5998 | return getCouldNotCompute(); |
| 5999 | |
| 6000 | // If this is a quadratic (3-term) AddRec {L,+,M,+,N}, find the roots of |
| 6001 | // the quadratic equation to solve it. |
| 6002 | if (AddRec->isQuadratic() && AddRec->getType()->isIntegerTy()) { |
| 6003 | std::pair<const SCEV *,const SCEV *> Roots = |
| 6004 | SolveQuadraticEquation(AddRec, *this); |
| 6005 | const SCEVConstant *R1 = dyn_cast<SCEVConstant>(Roots.first); |
| 6006 | const SCEVConstant *R2 = dyn_cast<SCEVConstant>(Roots.second); |
| 6007 | if (R1 && R2) { |
| 6008 | #if 0 |
| 6009 | dbgs() << "HFTZ: " << *V << " - sol#1: " << *R1 |
| 6010 | << " sol#2: " << *R2 << "\n"; |
| 6011 | #endif |
| 6012 | // Pick the smallest positive root value. |
| 6013 | if (ConstantInt *CB = |
| 6014 | dyn_cast<ConstantInt>(ConstantExpr::getICmp(CmpInst::ICMP_ULT, |
| 6015 | R1->getValue(), |
| 6016 | R2->getValue()))) { |
| 6017 | if (CB->getZExtValue() == false) |
| 6018 | std::swap(R1, R2); // R1 is the minimum root now. |
| 6019 | |
| 6020 | // We can only use this value if the chrec ends up with an exact zero |
| 6021 | // value at this index. When solving for "X*X != 5", for example, we |
| 6022 | // should not accept a root of 2. |
| 6023 | const SCEV *Val = AddRec->evaluateAtIteration(R1, *this); |
| 6024 | if (Val->isZero()) |
| 6025 | return R1; // We found a quadratic root! |
| 6026 | } |
| 6027 | } |
| 6028 | return getCouldNotCompute(); |
| 6029 | } |
| 6030 | |
| 6031 | // Otherwise we can only handle this if it is affine. |
| 6032 | if (!AddRec->isAffine()) |
| 6033 | return getCouldNotCompute(); |
| 6034 | |
| 6035 | // If this is an affine expression, the execution count of this branch is |
| 6036 | // the minimum unsigned root of the following equation: |
| 6037 | // |
| 6038 | // Start + Step*N = 0 (mod 2^BW) |
| 6039 | // |
| 6040 | // equivalent to: |
| 6041 | // |
| 6042 | // Step*N = -Start (mod 2^BW) |
| 6043 | // |
| 6044 | // where BW is the common bit width of Start and Step. |
| 6045 | |
| 6046 | // Get the initial value for the loop. |
| 6047 | const SCEV *Start = getSCEVAtScope(AddRec->getStart(), L->getParentLoop()); |
| 6048 | const SCEV *Step = getSCEVAtScope(AddRec->getOperand(1), L->getParentLoop()); |
| 6049 | |
| 6050 | // For now we handle only constant steps. |
| 6051 | // |
| 6052 | // TODO: Handle a nonconstant Step given AddRec<NUW>. If the |
| 6053 | // AddRec is NUW, then (in an unsigned sense) it cannot be counting up to wrap |
| 6054 | // to 0, it must be counting down to equal 0. Consequently, N = Start / -Step. |
| 6055 | // We have not yet seen any such cases. |
| 6056 | const SCEVConstant *StepC = dyn_cast<SCEVConstant>(Step); |
| 6057 | if (!StepC || StepC->getValue()->equalsInt(0)) |
| 6058 | return getCouldNotCompute(); |
| 6059 | |
| 6060 | // For positive steps (counting up until unsigned overflow): |
| 6061 | // N = -Start/Step (as unsigned) |
| 6062 | // For negative steps (counting down to zero): |
| 6063 | // N = Start/-Step |
| 6064 | // First compute the unsigned distance from zero in the direction of Step. |
| 6065 | bool CountDown = StepC->getValue()->getValue().isNegative(); |
| 6066 | const SCEV *Distance = CountDown ? Start : getNegativeSCEV(Start); |
| 6067 | |
| 6068 | // Handle unitary steps, which cannot wraparound. |
| 6069 | // 1*N = -Start; -1*N = Start (mod 2^BW), so: |
| 6070 | // N = Distance (as unsigned) |
| 6071 | if (StepC->getValue()->equalsInt(1) || StepC->getValue()->isAllOnesValue()) { |
| 6072 | ConstantRange CR = getUnsignedRange(Start); |
| 6073 | const SCEV *MaxBECount; |
| 6074 | if (!CountDown && CR.getUnsignedMin().isMinValue()) |
| 6075 | // When counting up, the worst starting value is 1, not 0. |
| 6076 | MaxBECount = CR.getUnsignedMax().isMinValue() |
| 6077 | ? getConstant(APInt::getMinValue(CR.getBitWidth())) |
| 6078 | : getConstant(APInt::getMaxValue(CR.getBitWidth())); |
| 6079 | else |
| 6080 | MaxBECount = getConstant(CountDown ? CR.getUnsignedMax() |
| 6081 | : -CR.getUnsignedMin()); |
| 6082 | return ExitLimit(Distance, MaxBECount); |
| 6083 | } |
| 6084 | |
| 6085 | // If the step exactly divides the distance then unsigned divide computes the |
| 6086 | // backedge count. |
| 6087 | const SCEV *Q, *R; |
| 6088 | ScalarEvolution &SE = *const_cast<ScalarEvolution *>(this); |
| 6089 | SCEVDivision::divide(SE, Distance, Step, &Q, &R); |
| 6090 | if (R->isZero()) { |
| 6091 | const SCEV *Exact = |
| 6092 | getUDivExactExpr(Distance, CountDown ? getNegativeSCEV(Step) : Step); |
| 6093 | return ExitLimit(Exact, Exact); |
| 6094 | } |
| 6095 | |
| 6096 | // If the condition controls loop exit (the loop exits only if the expression |
| 6097 | // is true) and the addition is no-wrap we can use unsigned divide to |
| 6098 | // compute the backedge count. In this case, the step may not divide the |
| 6099 | // distance, but we don't care because if the condition is "missed" the loop |
| 6100 | // will have undefined behavior due to wrapping. |
| 6101 | if (ControlsExit && AddRec->getNoWrapFlags(SCEV::FlagNW)) { |
| 6102 | const SCEV *Exact = |
| 6103 | getUDivExpr(Distance, CountDown ? getNegativeSCEV(Step) : Step); |
| 6104 | return ExitLimit(Exact, Exact); |
| 6105 | } |
| 6106 | |
| 6107 | // Then, try to solve the above equation provided that Start is constant. |
| 6108 | if (const SCEVConstant *StartC = dyn_cast<SCEVConstant>(Start)) |
| 6109 | return SolveLinEquationWithOverflow(StepC->getValue()->getValue(), |
| 6110 | -StartC->getValue()->getValue(), |
| 6111 | *this); |
| 6112 | return getCouldNotCompute(); |
| 6113 | } |
| 6114 | |
| 6115 | /// HowFarToNonZero - Return the number of times a backedge checking the |
| 6116 | /// specified value for nonzero will execute. If not computable, return |
| 6117 | /// CouldNotCompute |
| 6118 | ScalarEvolution::ExitLimit |
| 6119 | ScalarEvolution::HowFarToNonZero(const SCEV *V, const Loop *L) { |
| 6120 | // Loops that look like: while (X == 0) are very strange indeed. We don't |
| 6121 | // handle them yet except for the trivial case. This could be expanded in the |
| 6122 | // future as needed. |
| 6123 | |
| 6124 | // If the value is a constant, check to see if it is known to be non-zero |
| 6125 | // already. If so, the backedge will execute zero times. |
| 6126 | if (const SCEVConstant *C = dyn_cast<SCEVConstant>(V)) { |
| 6127 | if (!C->getValue()->isNullValue()) |
| 6128 | return getConstant(C->getType(), 0); |
| 6129 | return getCouldNotCompute(); // Otherwise it will loop infinitely. |
| 6130 | } |
| 6131 | |
| 6132 | // We could implement others, but I really doubt anyone writes loops like |
| 6133 | // this, and if they did, they would already be constant folded. |
| 6134 | return getCouldNotCompute(); |
| 6135 | } |
| 6136 | |
| 6137 | /// getPredecessorWithUniqueSuccessorForBB - Return a predecessor of BB |
| 6138 | /// (which may not be an immediate predecessor) which has exactly one |
| 6139 | /// successor from which BB is reachable, or null if no such block is |
| 6140 | /// found. |
| 6141 | /// |
| 6142 | std::pair<BasicBlock *, BasicBlock *> |
| 6143 | ScalarEvolution::getPredecessorWithUniqueSuccessorForBB(BasicBlock *BB) { |
| 6144 | // If the block has a unique predecessor, then there is no path from the |
| 6145 | // predecessor to the block that does not go through the direct edge |
| 6146 | // from the predecessor to the block. |
| 6147 | if (BasicBlock *Pred = BB->getSinglePredecessor()) |
| 6148 | return std::make_pair(Pred, BB); |
| 6149 | |
| 6150 | // A loop's header is defined to be a block that dominates the loop. |
| 6151 | // If the header has a unique predecessor outside the loop, it must be |
| 6152 | // a block that has exactly one successor that can reach the loop. |
| 6153 | if (Loop *L = LI->getLoopFor(BB)) |
| 6154 | return std::make_pair(L->getLoopPredecessor(), L->getHeader()); |
| 6155 | |
| 6156 | return std::pair<BasicBlock *, BasicBlock *>(); |
| 6157 | } |
| 6158 | |
| 6159 | /// HasSameValue - SCEV structural equivalence is usually sufficient for |
| 6160 | /// testing whether two expressions are equal, however for the purposes of |
| 6161 | /// looking for a condition guarding a loop, it can be useful to be a little |
| 6162 | /// more general, since a front-end may have replicated the controlling |
| 6163 | /// expression. |
| 6164 | /// |
| 6165 | static bool HasSameValue(const SCEV *A, const SCEV *B) { |
| 6166 | // Quick check to see if they are the same SCEV. |
| 6167 | if (A == B) return true; |
| 6168 | |
| 6169 | // Otherwise, if they're both SCEVUnknown, it's possible that they hold |
| 6170 | // two different instructions with the same value. Check for this case. |
| 6171 | if (const SCEVUnknown *AU = dyn_cast<SCEVUnknown>(A)) |
| 6172 | if (const SCEVUnknown *BU = dyn_cast<SCEVUnknown>(B)) |
| 6173 | if (const Instruction *AI = dyn_cast<Instruction>(AU->getValue())) |
| 6174 | if (const Instruction *BI = dyn_cast<Instruction>(BU->getValue())) |
| 6175 | if (AI->isIdenticalTo(BI) && !AI->mayReadFromMemory()) |
| 6176 | return true; |
| 6177 | |
| 6178 | // Otherwise assume they may have a different value. |
| 6179 | return false; |
| 6180 | } |
| 6181 | |
| 6182 | /// SimplifyICmpOperands - Simplify LHS and RHS in a comparison with |
| 6183 | /// predicate Pred. Return true iff any changes were made. |
| 6184 | /// |
| 6185 | bool ScalarEvolution::SimplifyICmpOperands(ICmpInst::Predicate &Pred, |
| 6186 | const SCEV *&LHS, const SCEV *&RHS, |
| 6187 | unsigned Depth) { |
| 6188 | bool Changed = false; |
| 6189 | |
| 6190 | // If we hit the max recursion limit bail out. |
| 6191 | if (Depth >= 3) |
| 6192 | return false; |
| 6193 | |
| 6194 | // Canonicalize a constant to the right side. |
| 6195 | if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(LHS)) { |
| 6196 | // Check for both operands constant. |
| 6197 | if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS)) { |
| 6198 | if (ConstantExpr::getICmp(Pred, |
| 6199 | LHSC->getValue(), |
| 6200 | RHSC->getValue())->isNullValue()) |
| 6201 | goto trivially_false; |
| 6202 | else |
| 6203 | goto trivially_true; |
| 6204 | } |
| 6205 | // Otherwise swap the operands to put the constant on the right. |
| 6206 | std::swap(LHS, RHS); |
| 6207 | Pred = ICmpInst::getSwappedPredicate(Pred); |
| 6208 | Changed = true; |
| 6209 | } |
| 6210 | |
| 6211 | // If we're comparing an addrec with a value which is loop-invariant in the |
| 6212 | // addrec's loop, put the addrec on the left. Also make a dominance check, |
| 6213 | // as both operands could be addrecs loop-invariant in each other's loop. |
| 6214 | if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(RHS)) { |
| 6215 | const Loop *L = AR->getLoop(); |
| 6216 | if (isLoopInvariant(LHS, L) && properlyDominates(LHS, L->getHeader())) { |
| 6217 | std::swap(LHS, RHS); |
| 6218 | Pred = ICmpInst::getSwappedPredicate(Pred); |
| 6219 | Changed = true; |
| 6220 | } |
| 6221 | } |
| 6222 | |
| 6223 | // If there's a constant operand, canonicalize comparisons with boundary |
| 6224 | // cases, and canonicalize *-or-equal comparisons to regular comparisons. |
| 6225 | if (const SCEVConstant *RC = dyn_cast<SCEVConstant>(RHS)) { |
| 6226 | const APInt &RA = RC->getValue()->getValue(); |
| 6227 | switch (Pred) { |
| 6228 | default: llvm_unreachable("Unexpected ICmpInst::Predicate value!")::llvm::llvm_unreachable_internal("Unexpected ICmpInst::Predicate value!" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 6228); |
| 6229 | case ICmpInst::ICMP_EQ: |
| 6230 | case ICmpInst::ICMP_NE: |
| 6231 | // Fold ((-1) * %a) + %b == 0 (equivalent to %b-%a == 0) into %a == %b. |
| 6232 | if (!RA) |
| 6233 | if (const SCEVAddExpr *AE = dyn_cast<SCEVAddExpr>(LHS)) |
| 6234 | if (const SCEVMulExpr *ME = dyn_cast<SCEVMulExpr>(AE->getOperand(0))) |
| 6235 | if (AE->getNumOperands() == 2 && ME->getNumOperands() == 2 && |
| 6236 | ME->getOperand(0)->isAllOnesValue()) { |
| 6237 | RHS = AE->getOperand(1); |
| 6238 | LHS = ME->getOperand(1); |
| 6239 | Changed = true; |
| 6240 | } |
| 6241 | break; |
| 6242 | case ICmpInst::ICMP_UGE: |
| 6243 | if ((RA - 1).isMinValue()) { |
| 6244 | Pred = ICmpInst::ICMP_NE; |
| 6245 | RHS = getConstant(RA - 1); |
| 6246 | Changed = true; |
| 6247 | break; |
| 6248 | } |
| 6249 | if (RA.isMaxValue()) { |
| 6250 | Pred = ICmpInst::ICMP_EQ; |
| 6251 | Changed = true; |
| 6252 | break; |
| 6253 | } |
| 6254 | if (RA.isMinValue()) goto trivially_true; |
| 6255 | |
| 6256 | Pred = ICmpInst::ICMP_UGT; |
| 6257 | RHS = getConstant(RA - 1); |
| 6258 | Changed = true; |
| 6259 | break; |
| 6260 | case ICmpInst::ICMP_ULE: |
| 6261 | if ((RA + 1).isMaxValue()) { |
| 6262 | Pred = ICmpInst::ICMP_NE; |
| 6263 | RHS = getConstant(RA + 1); |
| 6264 | Changed = true; |
| 6265 | break; |
| 6266 | } |
| 6267 | if (RA.isMinValue()) { |
| 6268 | Pred = ICmpInst::ICMP_EQ; |
| 6269 | Changed = true; |
| 6270 | break; |
| 6271 | } |
| 6272 | if (RA.isMaxValue()) goto trivially_true; |
| 6273 | |
| 6274 | Pred = ICmpInst::ICMP_ULT; |
| 6275 | RHS = getConstant(RA + 1); |
| 6276 | Changed = true; |
| 6277 | break; |
| 6278 | case ICmpInst::ICMP_SGE: |
| 6279 | if ((RA - 1).isMinSignedValue()) { |
| 6280 | Pred = ICmpInst::ICMP_NE; |
| 6281 | RHS = getConstant(RA - 1); |
| 6282 | Changed = true; |
| 6283 | break; |
| 6284 | } |
| 6285 | if (RA.isMaxSignedValue()) { |
| 6286 | Pred = ICmpInst::ICMP_EQ; |
| 6287 | Changed = true; |
| 6288 | break; |
| 6289 | } |
| 6290 | if (RA.isMinSignedValue()) goto trivially_true; |
| 6291 | |
| 6292 | Pred = ICmpInst::ICMP_SGT; |
| 6293 | RHS = getConstant(RA - 1); |
| 6294 | Changed = true; |
| 6295 | break; |
| 6296 | case ICmpInst::ICMP_SLE: |
| 6297 | if ((RA + 1).isMaxSignedValue()) { |
| 6298 | Pred = ICmpInst::ICMP_NE; |
| 6299 | RHS = getConstant(RA + 1); |
| 6300 | Changed = true; |
| 6301 | break; |
| 6302 | } |
| 6303 | if (RA.isMinSignedValue()) { |
| 6304 | Pred = ICmpInst::ICMP_EQ; |
| 6305 | Changed = true; |
| 6306 | break; |
| 6307 | } |
| 6308 | if (RA.isMaxSignedValue()) goto trivially_true; |
| 6309 | |
| 6310 | Pred = ICmpInst::ICMP_SLT; |
| 6311 | RHS = getConstant(RA + 1); |
| 6312 | Changed = true; |
| 6313 | break; |
| 6314 | case ICmpInst::ICMP_UGT: |
| 6315 | if (RA.isMinValue()) { |
| 6316 | Pred = ICmpInst::ICMP_NE; |
| 6317 | Changed = true; |
| 6318 | break; |
| 6319 | } |
| 6320 | if ((RA + 1).isMaxValue()) { |
| 6321 | Pred = ICmpInst::ICMP_EQ; |
| 6322 | RHS = getConstant(RA + 1); |
| 6323 | Changed = true; |
| 6324 | break; |
| 6325 | } |
| 6326 | if (RA.isMaxValue()) goto trivially_false; |
| 6327 | break; |
| 6328 | case ICmpInst::ICMP_ULT: |
| 6329 | if (RA.isMaxValue()) { |
| 6330 | Pred = ICmpInst::ICMP_NE; |
| 6331 | Changed = true; |
| 6332 | break; |
| 6333 | } |
| 6334 | if ((RA - 1).isMinValue()) { |
| 6335 | Pred = ICmpInst::ICMP_EQ; |
| 6336 | RHS = getConstant(RA - 1); |
| 6337 | Changed = true; |
| 6338 | break; |
| 6339 | } |
| 6340 | if (RA.isMinValue()) goto trivially_false; |
| 6341 | break; |
| 6342 | case ICmpInst::ICMP_SGT: |
| 6343 | if (RA.isMinSignedValue()) { |
| 6344 | Pred = ICmpInst::ICMP_NE; |
| 6345 | Changed = true; |
| 6346 | break; |
| 6347 | } |
| 6348 | if ((RA + 1).isMaxSignedValue()) { |
| 6349 | Pred = ICmpInst::ICMP_EQ; |
| 6350 | RHS = getConstant(RA + 1); |
| 6351 | Changed = true; |
| 6352 | break; |
| 6353 | } |
| 6354 | if (RA.isMaxSignedValue()) goto trivially_false; |
| 6355 | break; |
| 6356 | case ICmpInst::ICMP_SLT: |
| 6357 | if (RA.isMaxSignedValue()) { |
| 6358 | Pred = ICmpInst::ICMP_NE; |
| 6359 | Changed = true; |
| 6360 | break; |
| 6361 | } |
| 6362 | if ((RA - 1).isMinSignedValue()) { |
| 6363 | Pred = ICmpInst::ICMP_EQ; |
| 6364 | RHS = getConstant(RA - 1); |
| 6365 | Changed = true; |
| 6366 | break; |
| 6367 | } |
| 6368 | if (RA.isMinSignedValue()) goto trivially_false; |
| 6369 | break; |
| 6370 | } |
| 6371 | } |
| 6372 | |
| 6373 | // Check for obvious equality. |
| 6374 | if (HasSameValue(LHS, RHS)) { |
| 6375 | if (ICmpInst::isTrueWhenEqual(Pred)) |
| 6376 | goto trivially_true; |
| 6377 | if (ICmpInst::isFalseWhenEqual(Pred)) |
| 6378 | goto trivially_false; |
| 6379 | } |
| 6380 | |
| 6381 | // If possible, canonicalize GE/LE comparisons to GT/LT comparisons, by |
| 6382 | // adding or subtracting 1 from one of the operands. |
| 6383 | switch (Pred) { |
| 6384 | case ICmpInst::ICMP_SLE: |
| 6385 | if (!getSignedRange(RHS).getSignedMax().isMaxSignedValue()) { |
| 6386 | RHS = getAddExpr(getConstant(RHS->getType(), 1, true), RHS, |
| 6387 | SCEV::FlagNSW); |
| 6388 | Pred = ICmpInst::ICMP_SLT; |
| 6389 | Changed = true; |
| 6390 | } else if (!getSignedRange(LHS).getSignedMin().isMinSignedValue()) { |
| 6391 | LHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), LHS, |
| 6392 | SCEV::FlagNSW); |
| 6393 | Pred = ICmpInst::ICMP_SLT; |
| 6394 | Changed = true; |
| 6395 | } |
| 6396 | break; |
| 6397 | case ICmpInst::ICMP_SGE: |
| 6398 | if (!getSignedRange(RHS).getSignedMin().isMinSignedValue()) { |
| 6399 | RHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), RHS, |
| 6400 | SCEV::FlagNSW); |
| 6401 | Pred = ICmpInst::ICMP_SGT; |
| 6402 | Changed = true; |
| 6403 | } else if (!getSignedRange(LHS).getSignedMax().isMaxSignedValue()) { |
| 6404 | LHS = getAddExpr(getConstant(RHS->getType(), 1, true), LHS, |
| 6405 | SCEV::FlagNSW); |
| 6406 | Pred = ICmpInst::ICMP_SGT; |
| 6407 | Changed = true; |
| 6408 | } |
| 6409 | break; |
| 6410 | case ICmpInst::ICMP_ULE: |
| 6411 | if (!getUnsignedRange(RHS).getUnsignedMax().isMaxValue()) { |
| 6412 | RHS = getAddExpr(getConstant(RHS->getType(), 1, true), RHS, |
| 6413 | SCEV::FlagNUW); |
| 6414 | Pred = ICmpInst::ICMP_ULT; |
| 6415 | Changed = true; |
| 6416 | } else if (!getUnsignedRange(LHS).getUnsignedMin().isMinValue()) { |
| 6417 | LHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), LHS, |
| 6418 | SCEV::FlagNUW); |
| 6419 | Pred = ICmpInst::ICMP_ULT; |
| 6420 | Changed = true; |
| 6421 | } |
| 6422 | break; |
| 6423 | case ICmpInst::ICMP_UGE: |
| 6424 | if (!getUnsignedRange(RHS).getUnsignedMin().isMinValue()) { |
| 6425 | RHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), RHS, |
| 6426 | SCEV::FlagNUW); |
| 6427 | Pred = ICmpInst::ICMP_UGT; |
| 6428 | Changed = true; |
| 6429 | } else if (!getUnsignedRange(LHS).getUnsignedMax().isMaxValue()) { |
| 6430 | LHS = getAddExpr(getConstant(RHS->getType(), 1, true), LHS, |
| 6431 | SCEV::FlagNUW); |
| 6432 | Pred = ICmpInst::ICMP_UGT; |
| 6433 | Changed = true; |
| 6434 | } |
| 6435 | break; |
| 6436 | default: |
| 6437 | break; |
| 6438 | } |
| 6439 | |
| 6440 | // TODO: More simplifications are possible here. |
| 6441 | |
| 6442 | // Recursively simplify until we either hit a recursion limit or nothing |
| 6443 | // changes. |
| 6444 | if (Changed) |
| 6445 | return SimplifyICmpOperands(Pred, LHS, RHS, Depth+1); |
| 6446 | |
| 6447 | return Changed; |
| 6448 | |
| 6449 | trivially_true: |
| 6450 | // Return 0 == 0. |
| 6451 | LHS = RHS = getConstant(ConstantInt::getFalse(getContext())); |
| 6452 | Pred = ICmpInst::ICMP_EQ; |
| 6453 | return true; |
| 6454 | |
| 6455 | trivially_false: |
| 6456 | // Return 0 != 0. |
| 6457 | LHS = RHS = getConstant(ConstantInt::getFalse(getContext())); |
| 6458 | Pred = ICmpInst::ICMP_NE; |
| 6459 | return true; |
| 6460 | } |
| 6461 | |
| 6462 | bool ScalarEvolution::isKnownNegative(const SCEV *S) { |
| 6463 | return getSignedRange(S).getSignedMax().isNegative(); |
| 6464 | } |
| 6465 | |
| 6466 | bool ScalarEvolution::isKnownPositive(const SCEV *S) { |
| 6467 | return getSignedRange(S).getSignedMin().isStrictlyPositive(); |
| 6468 | } |
| 6469 | |
| 6470 | bool ScalarEvolution::isKnownNonNegative(const SCEV *S) { |
| 6471 | return !getSignedRange(S).getSignedMin().isNegative(); |
| 6472 | } |
| 6473 | |
| 6474 | bool ScalarEvolution::isKnownNonPositive(const SCEV *S) { |
| 6475 | return !getSignedRange(S).getSignedMax().isStrictlyPositive(); |
| 6476 | } |
| 6477 | |
| 6478 | bool ScalarEvolution::isKnownNonZero(const SCEV *S) { |
| 6479 | return isKnownNegative(S) || isKnownPositive(S); |
| 6480 | } |
| 6481 | |
| 6482 | bool ScalarEvolution::isKnownPredicate(ICmpInst::Predicate Pred, |
| 6483 | const SCEV *LHS, const SCEV *RHS) { |
| 6484 | // Canonicalize the inputs first. |
| 6485 | (void)SimplifyICmpOperands(Pred, LHS, RHS); |
| 6486 | |
| 6487 | // If LHS or RHS is an addrec, check to see if the condition is true in |
| 6488 | // every iteration of the loop. |
| 6489 | // If LHS and RHS are both addrec, both conditions must be true in |
| 6490 | // every iteration of the loop. |
| 6491 | const SCEVAddRecExpr *LAR = dyn_cast<SCEVAddRecExpr>(LHS); |
| 6492 | const SCEVAddRecExpr *RAR = dyn_cast<SCEVAddRecExpr>(RHS); |
| 6493 | bool LeftGuarded = false; |
| 6494 | bool RightGuarded = false; |
| 6495 | if (LAR) { |
| 6496 | const Loop *L = LAR->getLoop(); |
| 6497 | if (isLoopEntryGuardedByCond(L, Pred, LAR->getStart(), RHS) && |
| 6498 | isLoopBackedgeGuardedByCond(L, Pred, LAR->getPostIncExpr(*this), RHS)) { |
| 6499 | if (!RAR) return true; |
| 6500 | LeftGuarded = true; |
| 6501 | } |
| 6502 | } |
| 6503 | if (RAR) { |
| 6504 | const Loop *L = RAR->getLoop(); |
| 6505 | if (isLoopEntryGuardedByCond(L, Pred, LHS, RAR->getStart()) && |
| 6506 | isLoopBackedgeGuardedByCond(L, Pred, LHS, RAR->getPostIncExpr(*this))) { |
| 6507 | if (!LAR) return true; |
| 6508 | RightGuarded = true; |
| 6509 | } |
| 6510 | } |
| 6511 | if (LeftGuarded && RightGuarded) |
| 6512 | return true; |
| 6513 | |
| 6514 | // Otherwise see what can be done with known constant ranges. |
| 6515 | return isKnownPredicateWithRanges(Pred, LHS, RHS); |
| 6516 | } |
| 6517 | |
| 6518 | bool |
| 6519 | ScalarEvolution::isKnownPredicateWithRanges(ICmpInst::Predicate Pred, |
| 6520 | const SCEV *LHS, const SCEV *RHS) { |
| 6521 | if (HasSameValue(LHS, RHS)) |
| 6522 | return ICmpInst::isTrueWhenEqual(Pred); |
| 6523 | |
| 6524 | // This code is split out from isKnownPredicate because it is called from |
| 6525 | // within isLoopEntryGuardedByCond. |
| 6526 | switch (Pred) { |
| 6527 | default: |
| 6528 | llvm_unreachable("Unexpected ICmpInst::Predicate value!")::llvm::llvm_unreachable_internal("Unexpected ICmpInst::Predicate value!" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 6528); |
| 6529 | case ICmpInst::ICMP_SGT: |
| 6530 | std::swap(LHS, RHS); |
| 6531 | case ICmpInst::ICMP_SLT: { |
| 6532 | ConstantRange LHSRange = getSignedRange(LHS); |
| 6533 | ConstantRange RHSRange = getSignedRange(RHS); |
| 6534 | if (LHSRange.getSignedMax().slt(RHSRange.getSignedMin())) |
| 6535 | return true; |
| 6536 | if (LHSRange.getSignedMin().sge(RHSRange.getSignedMax())) |
| 6537 | return false; |
| 6538 | break; |
| 6539 | } |
| 6540 | case ICmpInst::ICMP_SGE: |
| 6541 | std::swap(LHS, RHS); |
| 6542 | case ICmpInst::ICMP_SLE: { |
| 6543 | ConstantRange LHSRange = getSignedRange(LHS); |
| 6544 | ConstantRange RHSRange = getSignedRange(RHS); |
| 6545 | if (LHSRange.getSignedMax().sle(RHSRange.getSignedMin())) |
| 6546 | return true; |
| 6547 | if (LHSRange.getSignedMin().sgt(RHSRange.getSignedMax())) |
| 6548 | return false; |
| 6549 | break; |
| 6550 | } |
| 6551 | case ICmpInst::ICMP_UGT: |
| 6552 | std::swap(LHS, RHS); |
| 6553 | case ICmpInst::ICMP_ULT: { |
| 6554 | ConstantRange LHSRange = getUnsignedRange(LHS); |
| 6555 | ConstantRange RHSRange = getUnsignedRange(RHS); |
| 6556 | if (LHSRange.getUnsignedMax().ult(RHSRange.getUnsignedMin())) |
| 6557 | return true; |
| 6558 | if (LHSRange.getUnsignedMin().uge(RHSRange.getUnsignedMax())) |
| 6559 | return false; |
| 6560 | break; |
| 6561 | } |
| 6562 | case ICmpInst::ICMP_UGE: |
| 6563 | std::swap(LHS, RHS); |
| 6564 | case ICmpInst::ICMP_ULE: { |
| 6565 | ConstantRange LHSRange = getUnsignedRange(LHS); |
| 6566 | ConstantRange RHSRange = getUnsignedRange(RHS); |
| 6567 | if (LHSRange.getUnsignedMax().ule(RHSRange.getUnsignedMin())) |
| 6568 | return true; |
| 6569 | if (LHSRange.getUnsignedMin().ugt(RHSRange.getUnsignedMax())) |
| 6570 | return false; |
| 6571 | break; |
| 6572 | } |
| 6573 | case ICmpInst::ICMP_NE: { |
| 6574 | if (getUnsignedRange(LHS).intersectWith(getUnsignedRange(RHS)).isEmptySet()) |
| 6575 | return true; |
| 6576 | if (getSignedRange(LHS).intersectWith(getSignedRange(RHS)).isEmptySet()) |
| 6577 | return true; |
| 6578 | |
| 6579 | const SCEV *Diff = getMinusSCEV(LHS, RHS); |
| 6580 | if (isKnownNonZero(Diff)) |
| 6581 | return true; |
| 6582 | break; |
| 6583 | } |
| 6584 | case ICmpInst::ICMP_EQ: |
| 6585 | // The check at the top of the function catches the case where |
| 6586 | // the values are known to be equal. |
| 6587 | break; |
| 6588 | } |
| 6589 | return false; |
| 6590 | } |
| 6591 | |
| 6592 | /// isLoopBackedgeGuardedByCond - Test whether the backedge of the loop is |
| 6593 | /// protected by a conditional between LHS and RHS. This is used to |
| 6594 | /// to eliminate casts. |
| 6595 | bool |
| 6596 | ScalarEvolution::isLoopBackedgeGuardedByCond(const Loop *L, |
| 6597 | ICmpInst::Predicate Pred, |
| 6598 | const SCEV *LHS, const SCEV *RHS) { |
| 6599 | // Interpret a null as meaning no loop, where there is obviously no guard |
| 6600 | // (interprocedural conditions notwithstanding). |
| 6601 | if (!L) return true; |
| 6602 | |
| 6603 | if (isKnownPredicateWithRanges(Pred, LHS, RHS)) return true; |
| 6604 | |
| 6605 | BasicBlock *Latch = L->getLoopLatch(); |
| 6606 | if (!Latch) |
| 6607 | return false; |
| 6608 | |
| 6609 | BranchInst *LoopContinuePredicate = |
| 6610 | dyn_cast<BranchInst>(Latch->getTerminator()); |
| 6611 | if (LoopContinuePredicate && LoopContinuePredicate->isConditional() && |
| 6612 | isImpliedCond(Pred, LHS, RHS, |
| 6613 | LoopContinuePredicate->getCondition(), |
| 6614 | LoopContinuePredicate->getSuccessor(0) != L->getHeader())) |
| 6615 | return true; |
| 6616 | |
| 6617 | // Check conditions due to any @llvm.assume intrinsics. |
| 6618 | for (auto &CI : AT->assumptions(F)) { |
| 6619 | if (!DT->dominates(CI, Latch->getTerminator())) |
| 6620 | continue; |
| 6621 | |
| 6622 | if (isImpliedCond(Pred, LHS, RHS, CI->getArgOperand(0), false)) |
| 6623 | return true; |
| 6624 | } |
| 6625 | |
| 6626 | return false; |
| 6627 | } |
| 6628 | |
| 6629 | /// isLoopEntryGuardedByCond - Test whether entry to the loop is protected |
| 6630 | /// by a conditional between LHS and RHS. This is used to help avoid max |
| 6631 | /// expressions in loop trip counts, and to eliminate casts. |
| 6632 | bool |
| 6633 | ScalarEvolution::isLoopEntryGuardedByCond(const Loop *L, |
| 6634 | ICmpInst::Predicate Pred, |
| 6635 | const SCEV *LHS, const SCEV *RHS) { |
| 6636 | // Interpret a null as meaning no loop, where there is obviously no guard |
| 6637 | // (interprocedural conditions notwithstanding). |
| 6638 | if (!L) return false; |
| 6639 | |
| 6640 | if (isKnownPredicateWithRanges(Pred, LHS, RHS)) return true; |
| 6641 | |
| 6642 | // Starting at the loop predecessor, climb up the predecessor chain, as long |
| 6643 | // as there are predecessors that can be found that have unique successors |
| 6644 | // leading to the original header. |
| 6645 | for (std::pair<BasicBlock *, BasicBlock *> |
| 6646 | Pair(L->getLoopPredecessor(), L->getHeader()); |
| 6647 | Pair.first; |
| 6648 | Pair = getPredecessorWithUniqueSuccessorForBB(Pair.first)) { |
| 6649 | |
| 6650 | BranchInst *LoopEntryPredicate = |
| 6651 | dyn_cast<BranchInst>(Pair.first->getTerminator()); |
| 6652 | if (!LoopEntryPredicate || |
| 6653 | LoopEntryPredicate->isUnconditional()) |
| 6654 | continue; |
| 6655 | |
| 6656 | if (isImpliedCond(Pred, LHS, RHS, |
| 6657 | LoopEntryPredicate->getCondition(), |
| 6658 | LoopEntryPredicate->getSuccessor(0) != Pair.second)) |
| 6659 | return true; |
| 6660 | } |
| 6661 | |
| 6662 | // Check conditions due to any @llvm.assume intrinsics. |
| 6663 | for (auto &CI : AT->assumptions(F)) { |
| 6664 | if (!DT->dominates(CI, L->getHeader())) |
| 6665 | continue; |
| 6666 | |
| 6667 | if (isImpliedCond(Pred, LHS, RHS, CI->getArgOperand(0), false)) |
| 6668 | return true; |
| 6669 | } |
| 6670 | |
| 6671 | return false; |
| 6672 | } |
| 6673 | |
| 6674 | /// RAII wrapper to prevent recursive application of isImpliedCond. |
| 6675 | /// ScalarEvolution's PendingLoopPredicates set must be empty unless we are |
| 6676 | /// currently evaluating isImpliedCond. |
| 6677 | struct MarkPendingLoopPredicate { |
| 6678 | Value *Cond; |
| 6679 | DenseSet<Value*> &LoopPreds; |
| 6680 | bool Pending; |
| 6681 | |
| 6682 | MarkPendingLoopPredicate(Value *C, DenseSet<Value*> &LP) |
| 6683 | : Cond(C), LoopPreds(LP) { |
| 6684 | Pending = !LoopPreds.insert(Cond).second; |
| 6685 | } |
| 6686 | ~MarkPendingLoopPredicate() { |
| 6687 | if (!Pending) |
| 6688 | LoopPreds.erase(Cond); |
| 6689 | } |
| 6690 | }; |
| 6691 | |
| 6692 | /// isImpliedCond - Test whether the condition described by Pred, LHS, |
| 6693 | /// and RHS is true whenever the given Cond value evaluates to true. |
| 6694 | bool ScalarEvolution::isImpliedCond(ICmpInst::Predicate Pred, |
| 6695 | const SCEV *LHS, const SCEV *RHS, |
| 6696 | Value *FoundCondValue, |
| 6697 | bool Inverse) { |
| 6698 | MarkPendingLoopPredicate Mark(FoundCondValue, PendingLoopPredicates); |
| 6699 | if (Mark.Pending) |
| 6700 | return false; |
| 6701 | |
| 6702 | // Recursively handle And and Or conditions. |
| 6703 | if (BinaryOperator *BO = dyn_cast<BinaryOperator>(FoundCondValue)) { |
| 6704 | if (BO->getOpcode() == Instruction::And) { |
| 6705 | if (!Inverse) |
| 6706 | return isImpliedCond(Pred, LHS, RHS, BO->getOperand(0), Inverse) || |
| 6707 | isImpliedCond(Pred, LHS, RHS, BO->getOperand(1), Inverse); |
| 6708 | } else if (BO->getOpcode() == Instruction::Or) { |
| 6709 | if (Inverse) |
| 6710 | return isImpliedCond(Pred, LHS, RHS, BO->getOperand(0), Inverse) || |
| 6711 | isImpliedCond(Pred, LHS, RHS, BO->getOperand(1), Inverse); |
| 6712 | } |
| 6713 | } |
| 6714 | |
| 6715 | ICmpInst *ICI = dyn_cast<ICmpInst>(FoundCondValue); |
| 6716 | if (!ICI) return false; |
| 6717 | |
| 6718 | // Bail if the ICmp's operands' types are wider than the needed type |
| 6719 | // before attempting to call getSCEV on them. This avoids infinite |
| 6720 | // recursion, since the analysis of widening casts can require loop |
| 6721 | // exit condition information for overflow checking, which would |
| 6722 | // lead back here. |
| 6723 | if (getTypeSizeInBits(LHS->getType()) < |
| 6724 | getTypeSizeInBits(ICI->getOperand(0)->getType())) |
| 6725 | return false; |
| 6726 | |
| 6727 | // Now that we found a conditional branch that dominates the loop or controls |
| 6728 | // the loop latch. Check to see if it is the comparison we are looking for. |
| 6729 | ICmpInst::Predicate FoundPred; |
| 6730 | if (Inverse) |
| 6731 | FoundPred = ICI->getInversePredicate(); |
| 6732 | else |
| 6733 | FoundPred = ICI->getPredicate(); |
| 6734 | |
| 6735 | const SCEV *FoundLHS = getSCEV(ICI->getOperand(0)); |
| 6736 | const SCEV *FoundRHS = getSCEV(ICI->getOperand(1)); |
| 6737 | |
| 6738 | // Balance the types. The case where FoundLHS' type is wider than |
| 6739 | // LHS' type is checked for above. |
| 6740 | if (getTypeSizeInBits(LHS->getType()) > |
| 6741 | getTypeSizeInBits(FoundLHS->getType())) { |
| 6742 | if (CmpInst::isSigned(FoundPred)) { |
| 6743 | FoundLHS = getSignExtendExpr(FoundLHS, LHS->getType()); |
| 6744 | FoundRHS = getSignExtendExpr(FoundRHS, LHS->getType()); |
| 6745 | } else { |
| 6746 | FoundLHS = getZeroExtendExpr(FoundLHS, LHS->getType()); |
| 6747 | FoundRHS = getZeroExtendExpr(FoundRHS, LHS->getType()); |
| 6748 | } |
| 6749 | } |
| 6750 | |
| 6751 | // Canonicalize the query to match the way instcombine will have |
| 6752 | // canonicalized the comparison. |
| 6753 | if (SimplifyICmpOperands(Pred, LHS, RHS)) |
| 6754 | if (LHS == RHS) |
| 6755 | return CmpInst::isTrueWhenEqual(Pred); |
| 6756 | if (SimplifyICmpOperands(FoundPred, FoundLHS, FoundRHS)) |
| 6757 | if (FoundLHS == FoundRHS) |
| 6758 | return CmpInst::isFalseWhenEqual(FoundPred); |
| 6759 | |
| 6760 | // Check to see if we can make the LHS or RHS match. |
| 6761 | if (LHS == FoundRHS || RHS == FoundLHS) { |
| 6762 | if (isa<SCEVConstant>(RHS)) { |
| 6763 | std::swap(FoundLHS, FoundRHS); |
| 6764 | FoundPred = ICmpInst::getSwappedPredicate(FoundPred); |
| 6765 | } else { |
| 6766 | std::swap(LHS, RHS); |
| 6767 | Pred = ICmpInst::getSwappedPredicate(Pred); |
| 6768 | } |
| 6769 | } |
| 6770 | |
| 6771 | // Check whether the found predicate is the same as the desired predicate. |
| 6772 | if (FoundPred == Pred) |
| 6773 | return isImpliedCondOperands(Pred, LHS, RHS, FoundLHS, FoundRHS); |
| 6774 | |
| 6775 | // Check whether swapping the found predicate makes it the same as the |
| 6776 | // desired predicate. |
| 6777 | if (ICmpInst::getSwappedPredicate(FoundPred) == Pred) { |
| 6778 | if (isa<SCEVConstant>(RHS)) |
| 6779 | return isImpliedCondOperands(Pred, LHS, RHS, FoundRHS, FoundLHS); |
| 6780 | else |
| 6781 | return isImpliedCondOperands(ICmpInst::getSwappedPredicate(Pred), |
| 6782 | RHS, LHS, FoundLHS, FoundRHS); |
| 6783 | } |
| 6784 | |
| 6785 | // Check whether the actual condition is beyond sufficient. |
| 6786 | if (FoundPred == ICmpInst::ICMP_EQ) |
| 6787 | if (ICmpInst::isTrueWhenEqual(Pred)) |
| 6788 | if (isImpliedCondOperands(Pred, LHS, RHS, FoundLHS, FoundRHS)) |
| 6789 | return true; |
| 6790 | if (Pred == ICmpInst::ICMP_NE) |
| 6791 | if (!ICmpInst::isTrueWhenEqual(FoundPred)) |
| 6792 | if (isImpliedCondOperands(FoundPred, LHS, RHS, FoundLHS, FoundRHS)) |
| 6793 | return true; |
| 6794 | |
| 6795 | // Otherwise assume the worst. |
| 6796 | return false; |
| 6797 | } |
| 6798 | |
| 6799 | /// isImpliedCondOperands - Test whether the condition described by Pred, |
| 6800 | /// LHS, and RHS is true whenever the condition described by Pred, FoundLHS, |
| 6801 | /// and FoundRHS is true. |
| 6802 | bool ScalarEvolution::isImpliedCondOperands(ICmpInst::Predicate Pred, |
| 6803 | const SCEV *LHS, const SCEV *RHS, |
| 6804 | const SCEV *FoundLHS, |
| 6805 | const SCEV *FoundRHS) { |
| 6806 | return isImpliedCondOperandsHelper(Pred, LHS, RHS, |
| 6807 | FoundLHS, FoundRHS) || |
| 6808 | // ~x < ~y --> x > y |
| 6809 | isImpliedCondOperandsHelper(Pred, LHS, RHS, |
| 6810 | getNotSCEV(FoundRHS), |
| 6811 | getNotSCEV(FoundLHS)); |
| 6812 | } |
| 6813 | |
| 6814 | /// isImpliedCondOperandsHelper - Test whether the condition described by |
| 6815 | /// Pred, LHS, and RHS is true whenever the condition described by Pred, |
| 6816 | /// FoundLHS, and FoundRHS is true. |
| 6817 | bool |
| 6818 | ScalarEvolution::isImpliedCondOperandsHelper(ICmpInst::Predicate Pred, |
| 6819 | const SCEV *LHS, const SCEV *RHS, |
| 6820 | const SCEV *FoundLHS, |
| 6821 | const SCEV *FoundRHS) { |
| 6822 | switch (Pred) { |
| 6823 | default: llvm_unreachable("Unexpected ICmpInst::Predicate value!")::llvm::llvm_unreachable_internal("Unexpected ICmpInst::Predicate value!" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 6823); |
| 6824 | case ICmpInst::ICMP_EQ: |
| 6825 | case ICmpInst::ICMP_NE: |
| 6826 | if (HasSameValue(LHS, FoundLHS) && HasSameValue(RHS, FoundRHS)) |
| 6827 | return true; |
| 6828 | break; |
| 6829 | case ICmpInst::ICMP_SLT: |
| 6830 | case ICmpInst::ICMP_SLE: |
| 6831 | if (isKnownPredicateWithRanges(ICmpInst::ICMP_SLE, LHS, FoundLHS) && |
| 6832 | isKnownPredicateWithRanges(ICmpInst::ICMP_SGE, RHS, FoundRHS)) |
| 6833 | return true; |
| 6834 | break; |
| 6835 | case ICmpInst::ICMP_SGT: |
| 6836 | case ICmpInst::ICMP_SGE: |
| 6837 | if (isKnownPredicateWithRanges(ICmpInst::ICMP_SGE, LHS, FoundLHS) && |
| 6838 | isKnownPredicateWithRanges(ICmpInst::ICMP_SLE, RHS, FoundRHS)) |
| 6839 | return true; |
| 6840 | break; |
| 6841 | case ICmpInst::ICMP_ULT: |
| 6842 | case ICmpInst::ICMP_ULE: |
| 6843 | if (isKnownPredicateWithRanges(ICmpInst::ICMP_ULE, LHS, FoundLHS) && |
| 6844 | isKnownPredicateWithRanges(ICmpInst::ICMP_UGE, RHS, FoundRHS)) |
| 6845 | return true; |
| 6846 | break; |
| 6847 | case ICmpInst::ICMP_UGT: |
| 6848 | case ICmpInst::ICMP_UGE: |
| 6849 | if (isKnownPredicateWithRanges(ICmpInst::ICMP_UGE, LHS, FoundLHS) && |
| 6850 | isKnownPredicateWithRanges(ICmpInst::ICMP_ULE, RHS, FoundRHS)) |
| 6851 | return true; |
| 6852 | break; |
| 6853 | } |
| 6854 | |
| 6855 | return false; |
| 6856 | } |
| 6857 | |
| 6858 | // Verify if an linear IV with positive stride can overflow when in a |
| 6859 | // less-than comparison, knowing the invariant term of the comparison, the |
| 6860 | // stride and the knowledge of NSW/NUW flags on the recurrence. |
| 6861 | bool ScalarEvolution::doesIVOverflowOnLT(const SCEV *RHS, const SCEV *Stride, |
| 6862 | bool IsSigned, bool NoWrap) { |
| 6863 | if (NoWrap) return false; |
| 6864 | |
| 6865 | unsigned BitWidth = getTypeSizeInBits(RHS->getType()); |
| 6866 | const SCEV *One = getConstant(Stride->getType(), 1); |
| 6867 | |
| 6868 | if (IsSigned) { |
| 6869 | APInt MaxRHS = getSignedRange(RHS).getSignedMax(); |
| 6870 | APInt MaxValue = APInt::getSignedMaxValue(BitWidth); |
| 6871 | APInt MaxStrideMinusOne = getSignedRange(getMinusSCEV(Stride, One)) |
| 6872 | .getSignedMax(); |
| 6873 | |
| 6874 | // SMaxRHS + SMaxStrideMinusOne > SMaxValue => overflow! |
| 6875 | return (MaxValue - MaxStrideMinusOne).slt(MaxRHS); |
| 6876 | } |
| 6877 | |
| 6878 | APInt MaxRHS = getUnsignedRange(RHS).getUnsignedMax(); |
| 6879 | APInt MaxValue = APInt::getMaxValue(BitWidth); |
| 6880 | APInt MaxStrideMinusOne = getUnsignedRange(getMinusSCEV(Stride, One)) |
| 6881 | .getUnsignedMax(); |
| 6882 | |
| 6883 | // UMaxRHS + UMaxStrideMinusOne > UMaxValue => overflow! |
| 6884 | return (MaxValue - MaxStrideMinusOne).ult(MaxRHS); |
| 6885 | } |
| 6886 | |
| 6887 | // Verify if an linear IV with negative stride can overflow when in a |
| 6888 | // greater-than comparison, knowing the invariant term of the comparison, |
| 6889 | // the stride and the knowledge of NSW/NUW flags on the recurrence. |
| 6890 | bool ScalarEvolution::doesIVOverflowOnGT(const SCEV *RHS, const SCEV *Stride, |
| 6891 | bool IsSigned, bool NoWrap) { |
| 6892 | if (NoWrap) return false; |
| 6893 | |
| 6894 | unsigned BitWidth = getTypeSizeInBits(RHS->getType()); |
| 6895 | const SCEV *One = getConstant(Stride->getType(), 1); |
| 6896 | |
| 6897 | if (IsSigned) { |
| 6898 | APInt MinRHS = getSignedRange(RHS).getSignedMin(); |
| 6899 | APInt MinValue = APInt::getSignedMinValue(BitWidth); |
| 6900 | APInt MaxStrideMinusOne = getSignedRange(getMinusSCEV(Stride, One)) |
| 6901 | .getSignedMax(); |
| 6902 | |
| 6903 | // SMinRHS - SMaxStrideMinusOne < SMinValue => overflow! |
| 6904 | return (MinValue + MaxStrideMinusOne).sgt(MinRHS); |
| 6905 | } |
| 6906 | |
| 6907 | APInt MinRHS = getUnsignedRange(RHS).getUnsignedMin(); |
| 6908 | APInt MinValue = APInt::getMinValue(BitWidth); |
| 6909 | APInt MaxStrideMinusOne = getUnsignedRange(getMinusSCEV(Stride, One)) |
| 6910 | .getUnsignedMax(); |
| 6911 | |
| 6912 | // UMinRHS - UMaxStrideMinusOne < UMinValue => overflow! |
| 6913 | return (MinValue + MaxStrideMinusOne).ugt(MinRHS); |
| 6914 | } |
| 6915 | |
| 6916 | // Compute the backedge taken count knowing the interval difference, the |
| 6917 | // stride and presence of the equality in the comparison. |
| 6918 | const SCEV *ScalarEvolution::computeBECount(const SCEV *Delta, const SCEV *Step, |
| 6919 | bool Equality) { |
| 6920 | const SCEV *One = getConstant(Step->getType(), 1); |
| 6921 | Delta = Equality ? getAddExpr(Delta, Step) |
| 6922 | : getAddExpr(Delta, getMinusSCEV(Step, One)); |
| 6923 | return getUDivExpr(Delta, Step); |
| 6924 | } |
| 6925 | |
| 6926 | /// HowManyLessThans - Return the number of times a backedge containing the |
| 6927 | /// specified less-than comparison will execute. If not computable, return |
| 6928 | /// CouldNotCompute. |
| 6929 | /// |
| 6930 | /// @param ControlsExit is true when the LHS < RHS condition directly controls |
| 6931 | /// the branch (loops exits only if condition is true). In this case, we can use |
| 6932 | /// NoWrapFlags to skip overflow checks. |
| 6933 | ScalarEvolution::ExitLimit |
| 6934 | ScalarEvolution::HowManyLessThans(const SCEV *LHS, const SCEV *RHS, |
| 6935 | const Loop *L, bool IsSigned, |
| 6936 | bool ControlsExit) { |
| 6937 | // We handle only IV < Invariant |
| 6938 | if (!isLoopInvariant(RHS, L)) |
| 6939 | return getCouldNotCompute(); |
| 6940 | |
| 6941 | const SCEVAddRecExpr *IV = dyn_cast<SCEVAddRecExpr>(LHS); |
| 6942 | |
| 6943 | // Avoid weird loops |
| 6944 | if (!IV || IV->getLoop() != L || !IV->isAffine()) |
| 6945 | return getCouldNotCompute(); |
| 6946 | |
| 6947 | bool NoWrap = ControlsExit && |
| 6948 | IV->getNoWrapFlags(IsSigned ? SCEV::FlagNSW : SCEV::FlagNUW); |
| 6949 | |
| 6950 | const SCEV *Stride = IV->getStepRecurrence(*this); |
| 6951 | |
| 6952 | // Avoid negative or zero stride values |
| 6953 | if (!isKnownPositive(Stride)) |
| 6954 | return getCouldNotCompute(); |
| 6955 | |
| 6956 | // Avoid proven overflow cases: this will ensure that the backedge taken count |
| 6957 | // will not generate any unsigned overflow. Relaxed no-overflow conditions |
| 6958 | // exploit NoWrapFlags, allowing to optimize in presence of undefined |
| 6959 | // behaviors like the case of C language. |
| 6960 | if (!Stride->isOne() && doesIVOverflowOnLT(RHS, Stride, IsSigned, NoWrap)) |
| 6961 | return getCouldNotCompute(); |
| 6962 | |
| 6963 | ICmpInst::Predicate Cond = IsSigned ? ICmpInst::ICMP_SLT |
| 6964 | : ICmpInst::ICMP_ULT; |
| 6965 | const SCEV *Start = IV->getStart(); |
| 6966 | const SCEV *End = RHS; |
| 6967 | if (!isLoopEntryGuardedByCond(L, Cond, getMinusSCEV(Start, Stride), RHS)) |
| 6968 | End = IsSigned ? getSMaxExpr(RHS, Start) |
| 6969 | : getUMaxExpr(RHS, Start); |
| 6970 | |
| 6971 | const SCEV *BECount = computeBECount(getMinusSCEV(End, Start), Stride, false); |
| 6972 | |
| 6973 | APInt MinStart = IsSigned ? getSignedRange(Start).getSignedMin() |
| 6974 | : getUnsignedRange(Start).getUnsignedMin(); |
| 6975 | |
| 6976 | APInt MinStride = IsSigned ? getSignedRange(Stride).getSignedMin() |
| 6977 | : getUnsignedRange(Stride).getUnsignedMin(); |
| 6978 | |
| 6979 | unsigned BitWidth = getTypeSizeInBits(LHS->getType()); |
| 6980 | APInt Limit = IsSigned ? APInt::getSignedMaxValue(BitWidth) - (MinStride - 1) |
| 6981 | : APInt::getMaxValue(BitWidth) - (MinStride - 1); |
| 6982 | |
| 6983 | // Although End can be a MAX expression we estimate MaxEnd considering only |
| 6984 | // the case End = RHS. This is safe because in the other case (End - Start) |
| 6985 | // is zero, leading to a zero maximum backedge taken count. |
| 6986 | APInt MaxEnd = |
| 6987 | IsSigned ? APIntOps::smin(getSignedRange(RHS).getSignedMax(), Limit) |
| 6988 | : APIntOps::umin(getUnsignedRange(RHS).getUnsignedMax(), Limit); |
| 6989 | |
| 6990 | const SCEV *MaxBECount; |
| 6991 | if (isa<SCEVConstant>(BECount)) |
| 6992 | MaxBECount = BECount; |
| 6993 | else |
| 6994 | MaxBECount = computeBECount(getConstant(MaxEnd - MinStart), |
| 6995 | getConstant(MinStride), false); |
| 6996 | |
| 6997 | if (isa<SCEVCouldNotCompute>(MaxBECount)) |
| 6998 | MaxBECount = BECount; |
| 6999 | |
| 7000 | return ExitLimit(BECount, MaxBECount); |
| 7001 | } |
| 7002 | |
| 7003 | ScalarEvolution::ExitLimit |
| 7004 | ScalarEvolution::HowManyGreaterThans(const SCEV *LHS, const SCEV *RHS, |
| 7005 | const Loop *L, bool IsSigned, |
| 7006 | bool ControlsExit) { |
| 7007 | // We handle only IV > Invariant |
| 7008 | if (!isLoopInvariant(RHS, L)) |
| 7009 | return getCouldNotCompute(); |
| 7010 | |
| 7011 | const SCEVAddRecExpr *IV = dyn_cast<SCEVAddRecExpr>(LHS); |
| 7012 | |
| 7013 | // Avoid weird loops |
| 7014 | if (!IV || IV->getLoop() != L || !IV->isAffine()) |
| 7015 | return getCouldNotCompute(); |
| 7016 | |
| 7017 | bool NoWrap = ControlsExit && |
| 7018 | IV->getNoWrapFlags(IsSigned ? SCEV::FlagNSW : SCEV::FlagNUW); |
| 7019 | |
| 7020 | const SCEV *Stride = getNegativeSCEV(IV->getStepRecurrence(*this)); |
| 7021 | |
| 7022 | // Avoid negative or zero stride values |
| 7023 | if (!isKnownPositive(Stride)) |
| 7024 | return getCouldNotCompute(); |
| 7025 | |
| 7026 | // Avoid proven overflow cases: this will ensure that the backedge taken count |
| 7027 | // will not generate any unsigned overflow. Relaxed no-overflow conditions |
| 7028 | // exploit NoWrapFlags, allowing to optimize in presence of undefined |
| 7029 | // behaviors like the case of C language. |
| 7030 | if (!Stride->isOne() && doesIVOverflowOnGT(RHS, Stride, IsSigned, NoWrap)) |
| 7031 | return getCouldNotCompute(); |
| 7032 | |
| 7033 | ICmpInst::Predicate Cond = IsSigned ? ICmpInst::ICMP_SGT |
| 7034 | : ICmpInst::ICMP_UGT; |
| 7035 | |
| 7036 | const SCEV *Start = IV->getStart(); |
| 7037 | const SCEV *End = RHS; |
| 7038 | if (!isLoopEntryGuardedByCond(L, Cond, getAddExpr(Start, Stride), RHS)) |
| 7039 | End = IsSigned ? getSMinExpr(RHS, Start) |
| 7040 | : getUMinExpr(RHS, Start); |
| 7041 | |
| 7042 | const SCEV *BECount = computeBECount(getMinusSCEV(Start, End), Stride, false); |
| 7043 | |
| 7044 | APInt MaxStart = IsSigned ? getSignedRange(Start).getSignedMax() |
| 7045 | : getUnsignedRange(Start).getUnsignedMax(); |
| 7046 | |
| 7047 | APInt MinStride = IsSigned ? getSignedRange(Stride).getSignedMin() |
| 7048 | : getUnsignedRange(Stride).getUnsignedMin(); |
| 7049 | |
| 7050 | unsigned BitWidth = getTypeSizeInBits(LHS->getType()); |
| 7051 | APInt Limit = IsSigned ? APInt::getSignedMinValue(BitWidth) + (MinStride - 1) |
| 7052 | : APInt::getMinValue(BitWidth) + (MinStride - 1); |
| 7053 | |
| 7054 | // Although End can be a MIN expression we estimate MinEnd considering only |
| 7055 | // the case End = RHS. This is safe because in the other case (Start - End) |
| 7056 | // is zero, leading to a zero maximum backedge taken count. |
| 7057 | APInt MinEnd = |
| 7058 | IsSigned ? APIntOps::smax(getSignedRange(RHS).getSignedMin(), Limit) |
| 7059 | : APIntOps::umax(getUnsignedRange(RHS).getUnsignedMin(), Limit); |
| 7060 | |
| 7061 | |
| 7062 | const SCEV *MaxBECount = getCouldNotCompute(); |
Value stored to 'MaxBECount' during its initialization is never read | |
| 7063 | if (isa<SCEVConstant>(BECount)) |
| 7064 | MaxBECount = BECount; |
| 7065 | else |
| 7066 | MaxBECount = computeBECount(getConstant(MaxStart - MinEnd), |
| 7067 | getConstant(MinStride), false); |
| 7068 | |
| 7069 | if (isa<SCEVCouldNotCompute>(MaxBECount)) |
| 7070 | MaxBECount = BECount; |
| 7071 | |
| 7072 | return ExitLimit(BECount, MaxBECount); |
| 7073 | } |
| 7074 | |
| 7075 | /// getNumIterationsInRange - Return the number of iterations of this loop that |
| 7076 | /// produce values in the specified constant range. Another way of looking at |
| 7077 | /// this is that it returns the first iteration number where the value is not in |
| 7078 | /// the condition, thus computing the exit count. If the iteration count can't |
| 7079 | /// be computed, an instance of SCEVCouldNotCompute is returned. |
| 7080 | const SCEV *SCEVAddRecExpr::getNumIterationsInRange(ConstantRange Range, |
| 7081 | ScalarEvolution &SE) const { |
| 7082 | if (Range.isFullSet()) // Infinite loop. |
| 7083 | return SE.getCouldNotCompute(); |
| 7084 | |
| 7085 | // If the start is a non-zero constant, shift the range to simplify things. |
| 7086 | if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(getStart())) |
| 7087 | if (!SC->getValue()->isZero()) { |
| 7088 | SmallVector<const SCEV *, 4> Operands(op_begin(), op_end()); |
| 7089 | Operands[0] = SE.getConstant(SC->getType(), 0); |
| 7090 | const SCEV *Shifted = SE.getAddRecExpr(Operands, getLoop(), |
| 7091 | getNoWrapFlags(FlagNW)); |
| 7092 | if (const SCEVAddRecExpr *ShiftedAddRec = |
| 7093 | dyn_cast<SCEVAddRecExpr>(Shifted)) |
| 7094 | return ShiftedAddRec->getNumIterationsInRange( |
| 7095 | Range.subtract(SC->getValue()->getValue()), SE); |
| 7096 | // This is strange and shouldn't happen. |
| 7097 | return SE.getCouldNotCompute(); |
| 7098 | } |
| 7099 | |
| 7100 | // The only time we can solve this is when we have all constant indices. |
| 7101 | // Otherwise, we cannot determine the overflow conditions. |
| 7102 | for (unsigned i = 0, e = getNumOperands(); i != e; ++i) |
| 7103 | if (!isa<SCEVConstant>(getOperand(i))) |
| 7104 | return SE.getCouldNotCompute(); |
| 7105 | |
| 7106 | |
| 7107 | // Okay at this point we know that all elements of the chrec are constants and |
| 7108 | // that the start element is zero. |
| 7109 | |
| 7110 | // First check to see if the range contains zero. If not, the first |
| 7111 | // iteration exits. |
| 7112 | unsigned BitWidth = SE.getTypeSizeInBits(getType()); |
| 7113 | if (!Range.contains(APInt(BitWidth, 0))) |
| 7114 | return SE.getConstant(getType(), 0); |
| 7115 | |
| 7116 | if (isAffine()) { |
| 7117 | // If this is an affine expression then we have this situation: |
| 7118 | // Solve {0,+,A} in Range === Ax in Range |
| 7119 | |
| 7120 | // We know that zero is in the range. If A is positive then we know that |
| 7121 | // the upper value of the range must be the first possible exit value. |
| 7122 | // If A is negative then the lower of the range is the last possible loop |
| 7123 | // value. Also note that we already checked for a full range. |
| 7124 | APInt One(BitWidth,1); |
| 7125 | APInt A = cast<SCEVConstant>(getOperand(1))->getValue()->getValue(); |
| 7126 | APInt End = A.sge(One) ? (Range.getUpper() - One) : Range.getLower(); |
| 7127 | |
| 7128 | // The exit value should be (End+A)/A. |
| 7129 | APInt ExitVal = (End + A).udiv(A); |
| 7130 | ConstantInt *ExitValue = ConstantInt::get(SE.getContext(), ExitVal); |
| 7131 | |
| 7132 | // Evaluate at the exit value. If we really did fall out of the valid |
| 7133 | // range, then we computed our trip count, otherwise wrap around or other |
| 7134 | // things must have happened. |
| 7135 | ConstantInt *Val = EvaluateConstantChrecAtConstant(this, ExitValue, SE); |
| 7136 | if (Range.contains(Val->getValue())) |
| 7137 | return SE.getCouldNotCompute(); // Something strange happened |
| 7138 | |
| 7139 | // Ensure that the previous value is in the range. This is a sanity check. |
| 7140 | assert(Range.contains(((Range.contains( EvaluateConstantChrecAtConstant(this, ConstantInt ::get(SE.getContext(), ExitVal - One), SE)->getValue()) && "Linear scev computation is off in a bad way!") ? static_cast <void> (0) : __assert_fail ("Range.contains( EvaluateConstantChrecAtConstant(this, ConstantInt::get(SE.getContext(), ExitVal - One), SE)->getValue()) && \"Linear scev computation is off in a bad way!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 7143, __PRETTY_FUNCTION__)) |
| 7141 | EvaluateConstantChrecAtConstant(this,((Range.contains( EvaluateConstantChrecAtConstant(this, ConstantInt ::get(SE.getContext(), ExitVal - One), SE)->getValue()) && "Linear scev computation is off in a bad way!") ? static_cast <void> (0) : __assert_fail ("Range.contains( EvaluateConstantChrecAtConstant(this, ConstantInt::get(SE.getContext(), ExitVal - One), SE)->getValue()) && \"Linear scev computation is off in a bad way!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 7143, __PRETTY_FUNCTION__)) |
| 7142 | ConstantInt::get(SE.getContext(), ExitVal - One), SE)->getValue()) &&((Range.contains( EvaluateConstantChrecAtConstant(this, ConstantInt ::get(SE.getContext(), ExitVal - One), SE)->getValue()) && "Linear scev computation is off in a bad way!") ? static_cast <void> (0) : __assert_fail ("Range.contains( EvaluateConstantChrecAtConstant(this, ConstantInt::get(SE.getContext(), ExitVal - One), SE)->getValue()) && \"Linear scev computation is off in a bad way!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 7143, __PRETTY_FUNCTION__)) |
| 7143 | "Linear scev computation is off in a bad way!")((Range.contains( EvaluateConstantChrecAtConstant(this, ConstantInt ::get(SE.getContext(), ExitVal - One), SE)->getValue()) && "Linear scev computation is off in a bad way!") ? static_cast <void> (0) : __assert_fail ("Range.contains( EvaluateConstantChrecAtConstant(this, ConstantInt::get(SE.getContext(), ExitVal - One), SE)->getValue()) && \"Linear scev computation is off in a bad way!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 7143, __PRETTY_FUNCTION__)); |
| 7144 | return SE.getConstant(ExitValue); |
| 7145 | } else if (isQuadratic()) { |
| 7146 | // If this is a quadratic (3-term) AddRec {L,+,M,+,N}, find the roots of the |
| 7147 | // quadratic equation to solve it. To do this, we must frame our problem in |
| 7148 | // terms of figuring out when zero is crossed, instead of when |
| 7149 | // Range.getUpper() is crossed. |
| 7150 | SmallVector<const SCEV *, 4> NewOps(op_begin(), op_end()); |
| 7151 | NewOps[0] = SE.getNegativeSCEV(SE.getConstant(Range.getUpper())); |
| 7152 | const SCEV *NewAddRec = SE.getAddRecExpr(NewOps, getLoop(), |
| 7153 | // getNoWrapFlags(FlagNW) |
| 7154 | FlagAnyWrap); |
| 7155 | |
| 7156 | // Next, solve the constructed addrec |
| 7157 | std::pair<const SCEV *,const SCEV *> Roots = |
| 7158 | SolveQuadraticEquation(cast<SCEVAddRecExpr>(NewAddRec), SE); |
| 7159 | const SCEVConstant *R1 = dyn_cast<SCEVConstant>(Roots.first); |
| 7160 | const SCEVConstant *R2 = dyn_cast<SCEVConstant>(Roots.second); |
| 7161 | if (R1) { |
| 7162 | // Pick the smallest positive root value. |
| 7163 | if (ConstantInt *CB = |
| 7164 | dyn_cast<ConstantInt>(ConstantExpr::getICmp(ICmpInst::ICMP_ULT, |
| 7165 | R1->getValue(), R2->getValue()))) { |
| 7166 | if (CB->getZExtValue() == false) |
| 7167 | std::swap(R1, R2); // R1 is the minimum root now. |
| 7168 | |
| 7169 | // Make sure the root is not off by one. The returned iteration should |
| 7170 | // not be in the range, but the previous one should be. When solving |
| 7171 | // for "X*X < 5", for example, we should not return a root of 2. |
| 7172 | ConstantInt *R1Val = EvaluateConstantChrecAtConstant(this, |
| 7173 | R1->getValue(), |
| 7174 | SE); |
| 7175 | if (Range.contains(R1Val->getValue())) { |
| 7176 | // The next iteration must be out of the range... |
| 7177 | ConstantInt *NextVal = |
| 7178 | ConstantInt::get(SE.getContext(), R1->getValue()->getValue()+1); |
| 7179 | |
| 7180 | R1Val = EvaluateConstantChrecAtConstant(this, NextVal, SE); |
| 7181 | if (!Range.contains(R1Val->getValue())) |
| 7182 | return SE.getConstant(NextVal); |
| 7183 | return SE.getCouldNotCompute(); // Something strange happened |
| 7184 | } |
| 7185 | |
| 7186 | // If R1 was not in the range, then it is a good return value. Make |
| 7187 | // sure that R1-1 WAS in the range though, just in case. |
| 7188 | ConstantInt *NextVal = |
| 7189 | ConstantInt::get(SE.getContext(), R1->getValue()->getValue()-1); |
| 7190 | R1Val = EvaluateConstantChrecAtConstant(this, NextVal, SE); |
| 7191 | if (Range.contains(R1Val->getValue())) |
| 7192 | return R1; |
| 7193 | return SE.getCouldNotCompute(); // Something strange happened |
| 7194 | } |
| 7195 | } |
| 7196 | } |
| 7197 | |
| 7198 | return SE.getCouldNotCompute(); |
| 7199 | } |
| 7200 | |
| 7201 | namespace { |
| 7202 | struct FindUndefs { |
| 7203 | bool Found; |
| 7204 | FindUndefs() : Found(false) {} |
| 7205 | |
| 7206 | bool follow(const SCEV *S) { |
| 7207 | if (const SCEVUnknown *C = dyn_cast<SCEVUnknown>(S)) { |
| 7208 | if (isa<UndefValue>(C->getValue())) |
| 7209 | Found = true; |
| 7210 | } else if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S)) { |
| 7211 | if (isa<UndefValue>(C->getValue())) |
| 7212 | Found = true; |
| 7213 | } |
| 7214 | |
| 7215 | // Keep looking if we haven't found it yet. |
| 7216 | return !Found; |
| 7217 | } |
| 7218 | bool isDone() const { |
| 7219 | // Stop recursion if we have found an undef. |
| 7220 | return Found; |
| 7221 | } |
| 7222 | }; |
| 7223 | } |
| 7224 | |
| 7225 | // Return true when S contains at least an undef value. |
| 7226 | static inline bool |
| 7227 | containsUndefs(const SCEV *S) { |
| 7228 | FindUndefs F; |
| 7229 | SCEVTraversal<FindUndefs> ST(F); |
| 7230 | ST.visitAll(S); |
| 7231 | |
| 7232 | return F.Found; |
| 7233 | } |
| 7234 | |
| 7235 | namespace { |
| 7236 | // Collect all steps of SCEV expressions. |
| 7237 | struct SCEVCollectStrides { |
| 7238 | ScalarEvolution &SE; |
| 7239 | SmallVectorImpl<const SCEV *> &Strides; |
| 7240 | |
| 7241 | SCEVCollectStrides(ScalarEvolution &SE, SmallVectorImpl<const SCEV *> &S) |
| 7242 | : SE(SE), Strides(S) {} |
| 7243 | |
| 7244 | bool follow(const SCEV *S) { |
| 7245 | if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) |
| 7246 | Strides.push_back(AR->getStepRecurrence(SE)); |
| 7247 | return true; |
| 7248 | } |
| 7249 | bool isDone() const { return false; } |
| 7250 | }; |
| 7251 | |
| 7252 | // Collect all SCEVUnknown and SCEVMulExpr expressions. |
| 7253 | struct SCEVCollectTerms { |
| 7254 | SmallVectorImpl<const SCEV *> &Terms; |
| 7255 | |
| 7256 | SCEVCollectTerms(SmallVectorImpl<const SCEV *> &T) |
| 7257 | : Terms(T) {} |
| 7258 | |
| 7259 | bool follow(const SCEV *S) { |
| 7260 | if (isa<SCEVUnknown>(S) || isa<SCEVMulExpr>(S)) { |
| 7261 | if (!containsUndefs(S)) |
| 7262 | Terms.push_back(S); |
| 7263 | |
| 7264 | // Stop recursion: once we collected a term, do not walk its operands. |
| 7265 | return false; |
| 7266 | } |
| 7267 | |
| 7268 | // Keep looking. |
| 7269 | return true; |
| 7270 | } |
| 7271 | bool isDone() const { return false; } |
| 7272 | }; |
| 7273 | } |
| 7274 | |
| 7275 | /// Find parametric terms in this SCEVAddRecExpr. |
| 7276 | void SCEVAddRecExpr::collectParametricTerms( |
| 7277 | ScalarEvolution &SE, SmallVectorImpl<const SCEV *> &Terms) const { |
| 7278 | SmallVector<const SCEV *, 4> Strides; |
| 7279 | SCEVCollectStrides StrideCollector(SE, Strides); |
| 7280 | visitAll(this, StrideCollector); |
| 7281 | |
| 7282 | DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Strides:\n"; for ( const SCEV *S : Strides) dbgs() << *S << "\n"; }; } } while (0) |
| 7283 | dbgs() << "Strides:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Strides:\n"; for ( const SCEV *S : Strides) dbgs() << *S << "\n"; }; } } while (0) |
| 7284 | for (const SCEV *S : Strides)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Strides:\n"; for ( const SCEV *S : Strides) dbgs() << *S << "\n"; }; } } while (0) |
| 7285 | dbgs() << *S << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Strides:\n"; for ( const SCEV *S : Strides) dbgs() << *S << "\n"; }; } } while (0) |
| 7286 | })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Strides:\n"; for ( const SCEV *S : Strides) dbgs() << *S << "\n"; }; } } while (0); |
| 7287 | |
| 7288 | for (const SCEV *S : Strides) { |
| 7289 | SCEVCollectTerms TermCollector(Terms); |
| 7290 | visitAll(S, TermCollector); |
| 7291 | } |
| 7292 | |
| 7293 | DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while (0) |
| 7294 | dbgs() << "Terms:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while (0) |
| 7295 | for (const SCEV *T : Terms)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while (0) |
| 7296 | dbgs() << *T << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while (0) |
| 7297 | })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while (0); |
| 7298 | } |
| 7299 | |
| 7300 | static bool findArrayDimensionsRec(ScalarEvolution &SE, |
| 7301 | SmallVectorImpl<const SCEV *> &Terms, |
| 7302 | SmallVectorImpl<const SCEV *> &Sizes) { |
| 7303 | int Last = Terms.size() - 1; |
| 7304 | const SCEV *Step = Terms[Last]; |
| 7305 | |
| 7306 | // End of recursion. |
| 7307 | if (Last == 0) { |
| 7308 | if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(Step)) { |
| 7309 | SmallVector<const SCEV *, 2> Qs; |
| 7310 | for (const SCEV *Op : M->operands()) |
| 7311 | if (!isa<SCEVConstant>(Op)) |
| 7312 | Qs.push_back(Op); |
| 7313 | |
| 7314 | Step = SE.getMulExpr(Qs); |
| 7315 | } |
| 7316 | |
| 7317 | Sizes.push_back(Step); |
| 7318 | return true; |
| 7319 | } |
| 7320 | |
| 7321 | for (const SCEV *&Term : Terms) { |
| 7322 | // Normalize the terms before the next call to findArrayDimensionsRec. |
| 7323 | const SCEV *Q, *R; |
| 7324 | SCEVDivision::divide(SE, Term, Step, &Q, &R); |
| 7325 | |
| 7326 | // Bail out when GCD does not evenly divide one of the terms. |
| 7327 | if (!R->isZero()) |
| 7328 | return false; |
| 7329 | |
| 7330 | Term = Q; |
| 7331 | } |
| 7332 | |
| 7333 | // Remove all SCEVConstants. |
| 7334 | Terms.erase(std::remove_if(Terms.begin(), Terms.end(), [](const SCEV *E) { |
| 7335 | return isa<SCEVConstant>(E); |
| 7336 | }), |
| 7337 | Terms.end()); |
| 7338 | |
| 7339 | if (Terms.size() > 0) |
| 7340 | if (!findArrayDimensionsRec(SE, Terms, Sizes)) |
| 7341 | return false; |
| 7342 | |
| 7343 | Sizes.push_back(Step); |
| 7344 | return true; |
| 7345 | } |
| 7346 | |
| 7347 | namespace { |
| 7348 | struct FindParameter { |
| 7349 | bool FoundParameter; |
| 7350 | FindParameter() : FoundParameter(false) {} |
| 7351 | |
| 7352 | bool follow(const SCEV *S) { |
| 7353 | if (isa<SCEVUnknown>(S)) { |
| 7354 | FoundParameter = true; |
| 7355 | // Stop recursion: we found a parameter. |
| 7356 | return false; |
| 7357 | } |
| 7358 | // Keep looking. |
| 7359 | return true; |
| 7360 | } |
| 7361 | bool isDone() const { |
| 7362 | // Stop recursion if we have found a parameter. |
| 7363 | return FoundParameter; |
| 7364 | } |
| 7365 | }; |
| 7366 | } |
| 7367 | |
| 7368 | // Returns true when S contains at least a SCEVUnknown parameter. |
| 7369 | static inline bool |
| 7370 | containsParameters(const SCEV *S) { |
| 7371 | FindParameter F; |
| 7372 | SCEVTraversal<FindParameter> ST(F); |
| 7373 | ST.visitAll(S); |
| 7374 | |
| 7375 | return F.FoundParameter; |
| 7376 | } |
| 7377 | |
| 7378 | // Returns true when one of the SCEVs of Terms contains a SCEVUnknown parameter. |
| 7379 | static inline bool |
| 7380 | containsParameters(SmallVectorImpl<const SCEV *> &Terms) { |
| 7381 | for (const SCEV *T : Terms) |
| 7382 | if (containsParameters(T)) |
| 7383 | return true; |
| 7384 | return false; |
| 7385 | } |
| 7386 | |
| 7387 | // Return the number of product terms in S. |
| 7388 | static inline int numberOfTerms(const SCEV *S) { |
| 7389 | if (const SCEVMulExpr *Expr = dyn_cast<SCEVMulExpr>(S)) |
| 7390 | return Expr->getNumOperands(); |
| 7391 | return 1; |
| 7392 | } |
| 7393 | |
| 7394 | static const SCEV *removeConstantFactors(ScalarEvolution &SE, const SCEV *T) { |
| 7395 | if (isa<SCEVConstant>(T)) |
| 7396 | return nullptr; |
| 7397 | |
| 7398 | if (isa<SCEVUnknown>(T)) |
| 7399 | return T; |
| 7400 | |
| 7401 | if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(T)) { |
| 7402 | SmallVector<const SCEV *, 2> Factors; |
| 7403 | for (const SCEV *Op : M->operands()) |
| 7404 | if (!isa<SCEVConstant>(Op)) |
| 7405 | Factors.push_back(Op); |
| 7406 | |
| 7407 | return SE.getMulExpr(Factors); |
| 7408 | } |
| 7409 | |
| 7410 | return T; |
| 7411 | } |
| 7412 | |
| 7413 | /// Return the size of an element read or written by Inst. |
| 7414 | const SCEV *ScalarEvolution::getElementSize(Instruction *Inst) { |
| 7415 | Type *Ty; |
| 7416 | if (StoreInst *Store = dyn_cast<StoreInst>(Inst)) |
| 7417 | Ty = Store->getValueOperand()->getType(); |
| 7418 | else if (LoadInst *Load = dyn_cast<LoadInst>(Inst)) |
| 7419 | Ty = Load->getType(); |
| 7420 | else |
| 7421 | return nullptr; |
| 7422 | |
| 7423 | Type *ETy = getEffectiveSCEVType(PointerType::getUnqual(Ty)); |
| 7424 | return getSizeOfExpr(ETy, Ty); |
| 7425 | } |
| 7426 | |
| 7427 | /// Second step of delinearization: compute the array dimensions Sizes from the |
| 7428 | /// set of Terms extracted from the memory access function of this SCEVAddRec. |
| 7429 | void ScalarEvolution::findArrayDimensions(SmallVectorImpl<const SCEV *> &Terms, |
| 7430 | SmallVectorImpl<const SCEV *> &Sizes, |
| 7431 | const SCEV *ElementSize) const { |
| 7432 | |
| 7433 | if (Terms.size() < 1 || !ElementSize) |
| 7434 | return; |
| 7435 | |
| 7436 | // Early return when Terms do not contain parameters: we do not delinearize |
| 7437 | // non parametric SCEVs. |
| 7438 | if (!containsParameters(Terms)) |
| 7439 | return; |
| 7440 | |
| 7441 | DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while (0) |
| 7442 | dbgs() << "Terms:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while (0) |
| 7443 | for (const SCEV *T : Terms)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while (0) |
| 7444 | dbgs() << *T << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while (0) |
| 7445 | })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while (0); |
| 7446 | |
| 7447 | // Remove duplicates. |
| 7448 | std::sort(Terms.begin(), Terms.end()); |
| 7449 | Terms.erase(std::unique(Terms.begin(), Terms.end()), Terms.end()); |
| 7450 | |
| 7451 | // Put larger terms first. |
| 7452 | std::sort(Terms.begin(), Terms.end(), [](const SCEV *LHS, const SCEV *RHS) { |
| 7453 | return numberOfTerms(LHS) > numberOfTerms(RHS); |
| 7454 | }); |
| 7455 | |
| 7456 | ScalarEvolution &SE = *const_cast<ScalarEvolution *>(this); |
| 7457 | |
| 7458 | // Divide all terms by the element size. |
| 7459 | for (const SCEV *&Term : Terms) { |
| 7460 | const SCEV *Q, *R; |
| 7461 | SCEVDivision::divide(SE, Term, ElementSize, &Q, &R); |
| 7462 | Term = Q; |
| 7463 | } |
| 7464 | |
| 7465 | SmallVector<const SCEV *, 4> NewTerms; |
| 7466 | |
| 7467 | // Remove constant factors. |
| 7468 | for (const SCEV *T : Terms) |
| 7469 | if (const SCEV *NewT = removeConstantFactors(SE, T)) |
| 7470 | NewTerms.push_back(NewT); |
| 7471 | |
| 7472 | DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Terms after sorting:\n" ; for (const SCEV *T : NewTerms) dbgs() << *T << "\n" ; }; } } while (0) |
| 7473 | dbgs() << "Terms after sorting:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Terms after sorting:\n" ; for (const SCEV *T : NewTerms) dbgs() << *T << "\n" ; }; } } while (0) |
| 7474 | for (const SCEV *T : NewTerms)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Terms after sorting:\n" ; for (const SCEV *T : NewTerms) dbgs() << *T << "\n" ; }; } } while (0) |
| 7475 | dbgs() << *T << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Terms after sorting:\n" ; for (const SCEV *T : NewTerms) dbgs() << *T << "\n" ; }; } } while (0) |
| 7476 | })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Terms after sorting:\n" ; for (const SCEV *T : NewTerms) dbgs() << *T << "\n" ; }; } } while (0); |
| 7477 | |
| 7478 | if (NewTerms.empty() || |
| 7479 | !findArrayDimensionsRec(SE, NewTerms, Sizes)) { |
| 7480 | Sizes.clear(); |
| 7481 | return; |
| 7482 | } |
| 7483 | |
| 7484 | // The last element to be pushed into Sizes is the size of an element. |
| 7485 | Sizes.push_back(ElementSize); |
| 7486 | |
| 7487 | DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Sizes:\n"; for (const SCEV *S : Sizes) dbgs() << *S << "\n"; }; } } while (0) |
| 7488 | dbgs() << "Sizes:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Sizes:\n"; for (const SCEV *S : Sizes) dbgs() << *S << "\n"; }; } } while (0) |
| 7489 | for (const SCEV *S : Sizes)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Sizes:\n"; for (const SCEV *S : Sizes) dbgs() << *S << "\n"; }; } } while (0) |
| 7490 | dbgs() << *S << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Sizes:\n"; for (const SCEV *S : Sizes) dbgs() << *S << "\n"; }; } } while (0) |
| 7491 | })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Sizes:\n"; for (const SCEV *S : Sizes) dbgs() << *S << "\n"; }; } } while (0); |
| 7492 | } |
| 7493 | |
| 7494 | /// Third step of delinearization: compute the access functions for the |
| 7495 | /// Subscripts based on the dimensions in Sizes. |
| 7496 | void SCEVAddRecExpr::computeAccessFunctions( |
| 7497 | ScalarEvolution &SE, SmallVectorImpl<const SCEV *> &Subscripts, |
| 7498 | SmallVectorImpl<const SCEV *> &Sizes) const { |
| 7499 | |
| 7500 | // Early exit in case this SCEV is not an affine multivariate function. |
| 7501 | if (Sizes.empty() || !this->isAffine()) |
| 7502 | return; |
| 7503 | |
| 7504 | const SCEV *Res = this; |
| 7505 | int Last = Sizes.size() - 1; |
| 7506 | for (int i = Last; i >= 0; i--) { |
| 7507 | const SCEV *Q, *R; |
| 7508 | SCEVDivision::divide(SE, Res, Sizes[i], &Q, &R); |
| 7509 | |
| 7510 | DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Res: " << *Res << "\n"; dbgs() << "Sizes[i]: " << *Sizes[ i] << "\n"; dbgs() << "Res divided by Sizes[i]:\n" ; dbgs() << "Quotient: " << *Q << "\n"; dbgs () << "Remainder: " << *R << "\n"; }; } } while (0) |
| 7511 | dbgs() << "Res: " << *Res << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Res: " << *Res << "\n"; dbgs() << "Sizes[i]: " << *Sizes[ i] << "\n"; dbgs() << "Res divided by Sizes[i]:\n" ; dbgs() << "Quotient: " << *Q << "\n"; dbgs () << "Remainder: " << *R << "\n"; }; } } while (0) |
| 7512 | dbgs() << "Sizes[i]: " << *Sizes[i] << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Res: " << *Res << "\n"; dbgs() << "Sizes[i]: " << *Sizes[ i] << "\n"; dbgs() << "Res divided by Sizes[i]:\n" ; dbgs() << "Quotient: " << *Q << "\n"; dbgs () << "Remainder: " << *R << "\n"; }; } } while (0) |
| 7513 | dbgs() << "Res divided by Sizes[i]:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Res: " << *Res << "\n"; dbgs() << "Sizes[i]: " << *Sizes[ i] << "\n"; dbgs() << "Res divided by Sizes[i]:\n" ; dbgs() << "Quotient: " << *Q << "\n"; dbgs () << "Remainder: " << *R << "\n"; }; } } while (0) |
| 7514 | dbgs() << "Quotient: " << *Q << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Res: " << *Res << "\n"; dbgs() << "Sizes[i]: " << *Sizes[ i] << "\n"; dbgs() << "Res divided by Sizes[i]:\n" ; dbgs() << "Quotient: " << *Q << "\n"; dbgs () << "Remainder: " << *R << "\n"; }; } } while (0) |
| 7515 | dbgs() << "Remainder: " << *R << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Res: " << *Res << "\n"; dbgs() << "Sizes[i]: " << *Sizes[ i] << "\n"; dbgs() << "Res divided by Sizes[i]:\n" ; dbgs() << "Quotient: " << *Q << "\n"; dbgs () << "Remainder: " << *R << "\n"; }; } } while (0) |
| 7516 | })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Res: " << *Res << "\n"; dbgs() << "Sizes[i]: " << *Sizes[ i] << "\n"; dbgs() << "Res divided by Sizes[i]:\n" ; dbgs() << "Quotient: " << *Q << "\n"; dbgs () << "Remainder: " << *R << "\n"; }; } } while (0); |
| 7517 | |
| 7518 | Res = Q; |
| 7519 | |
| 7520 | // Do not record the last subscript corresponding to the size of elements in |
| 7521 | // the array. |
| 7522 | if (i == Last) { |
| 7523 | |
| 7524 | // Bail out if the remainder is too complex. |
| 7525 | if (isa<SCEVAddRecExpr>(R)) { |
| 7526 | Subscripts.clear(); |
| 7527 | Sizes.clear(); |
| 7528 | return; |
| 7529 | } |
| 7530 | |
| 7531 | continue; |
| 7532 | } |
| 7533 | |
| 7534 | // Record the access function for the current subscript. |
| 7535 | Subscripts.push_back(R); |
| 7536 | } |
| 7537 | |
| 7538 | // Also push in last position the remainder of the last division: it will be |
| 7539 | // the access function of the innermost dimension. |
| 7540 | Subscripts.push_back(Res); |
| 7541 | |
| 7542 | std::reverse(Subscripts.begin(), Subscripts.end()); |
| 7543 | |
| 7544 | DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Subscripts:\n"; for (const SCEV *S : Subscripts) dbgs() << *S << "\n" ; }; } } while (0) |
| 7545 | dbgs() << "Subscripts:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Subscripts:\n"; for (const SCEV *S : Subscripts) dbgs() << *S << "\n" ; }; } } while (0) |
| 7546 | for (const SCEV *S : Subscripts)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Subscripts:\n"; for (const SCEV *S : Subscripts) dbgs() << *S << "\n" ; }; } } while (0) |
| 7547 | dbgs() << *S << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Subscripts:\n"; for (const SCEV *S : Subscripts) dbgs() << *S << "\n" ; }; } } while (0) |
| 7548 | })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Subscripts:\n"; for (const SCEV *S : Subscripts) dbgs() << *S << "\n" ; }; } } while (0); |
| 7549 | } |
| 7550 | |
| 7551 | /// Splits the SCEV into two vectors of SCEVs representing the subscripts and |
| 7552 | /// sizes of an array access. Returns the remainder of the delinearization that |
| 7553 | /// is the offset start of the array. The SCEV->delinearize algorithm computes |
| 7554 | /// the multiples of SCEV coefficients: that is a pattern matching of sub |
| 7555 | /// expressions in the stride and base of a SCEV corresponding to the |
| 7556 | /// computation of a GCD (greatest common divisor) of base and stride. When |
| 7557 | /// SCEV->delinearize fails, it returns the SCEV unchanged. |
| 7558 | /// |
| 7559 | /// For example: when analyzing the memory access A[i][j][k] in this loop nest |
| 7560 | /// |
| 7561 | /// void foo(long n, long m, long o, double A[n][m][o]) { |
| 7562 | /// |
| 7563 | /// for (long i = 0; i < n; i++) |
| 7564 | /// for (long j = 0; j < m; j++) |
| 7565 | /// for (long k = 0; k < o; k++) |
| 7566 | /// A[i][j][k] = 1.0; |
| 7567 | /// } |
| 7568 | /// |
| 7569 | /// the delinearization input is the following AddRec SCEV: |
| 7570 | /// |
| 7571 | /// AddRec: {{{%A,+,(8 * %m * %o)}<%for.i>,+,(8 * %o)}<%for.j>,+,8}<%for.k> |
| 7572 | /// |
| 7573 | /// From this SCEV, we are able to say that the base offset of the access is %A |
| 7574 | /// because it appears as an offset that does not divide any of the strides in |
| 7575 | /// the loops: |
| 7576 | /// |
| 7577 | /// CHECK: Base offset: %A |
| 7578 | /// |
| 7579 | /// and then SCEV->delinearize determines the size of some of the dimensions of |
| 7580 | /// the array as these are the multiples by which the strides are happening: |
| 7581 | /// |
| 7582 | /// CHECK: ArrayDecl[UnknownSize][%m][%o] with elements of sizeof(double) bytes. |
| 7583 | /// |
| 7584 | /// Note that the outermost dimension remains of UnknownSize because there are |
| 7585 | /// no strides that would help identifying the size of the last dimension: when |
| 7586 | /// the array has been statically allocated, one could compute the size of that |
| 7587 | /// dimension by dividing the overall size of the array by the size of the known |
| 7588 | /// dimensions: %m * %o * 8. |
| 7589 | /// |
| 7590 | /// Finally delinearize provides the access functions for the array reference |
| 7591 | /// that does correspond to A[i][j][k] of the above C testcase: |
| 7592 | /// |
| 7593 | /// CHECK: ArrayRef[{0,+,1}<%for.i>][{0,+,1}<%for.j>][{0,+,1}<%for.k>] |
| 7594 | /// |
| 7595 | /// The testcases are checking the output of a function pass: |
| 7596 | /// DelinearizationPass that walks through all loads and stores of a function |
| 7597 | /// asking for the SCEV of the memory access with respect to all enclosing |
| 7598 | /// loops, calling SCEV->delinearize on that and printing the results. |
| 7599 | |
| 7600 | void SCEVAddRecExpr::delinearize(ScalarEvolution &SE, |
| 7601 | SmallVectorImpl<const SCEV *> &Subscripts, |
| 7602 | SmallVectorImpl<const SCEV *> &Sizes, |
| 7603 | const SCEV *ElementSize) const { |
| 7604 | // First step: collect parametric terms. |
| 7605 | SmallVector<const SCEV *, 4> Terms; |
| 7606 | collectParametricTerms(SE, Terms); |
| 7607 | |
| 7608 | if (Terms.empty()) |
| 7609 | return; |
| 7610 | |
| 7611 | // Second step: find subscript sizes. |
| 7612 | SE.findArrayDimensions(Terms, Sizes, ElementSize); |
| 7613 | |
| 7614 | if (Sizes.empty()) |
| 7615 | return; |
| 7616 | |
| 7617 | // Third step: compute the access functions for each subscript. |
| 7618 | computeAccessFunctions(SE, Subscripts, Sizes); |
| 7619 | |
| 7620 | if (Subscripts.empty()) |
| 7621 | return; |
| 7622 | |
| 7623 | DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "succeeded to delinearize " << *this << "\n"; dbgs() << "ArrayDecl[UnknownSize]" ; for (const SCEV *S : Sizes) dbgs() << "[" << *S << "]"; dbgs() << "\nArrayRef"; for (const SCEV * S : Subscripts) dbgs() << "[" << *S << "]"; dbgs() << "\n"; }; } } while (0) |
| 7624 | dbgs() << "succeeded to delinearize " << *this << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "succeeded to delinearize " << *this << "\n"; dbgs() << "ArrayDecl[UnknownSize]" ; for (const SCEV *S : Sizes) dbgs() << "[" << *S << "]"; dbgs() << "\nArrayRef"; for (const SCEV * S : Subscripts) dbgs() << "[" << *S << "]"; dbgs() << "\n"; }; } } while (0) |
| 7625 | dbgs() << "ArrayDecl[UnknownSize]";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "succeeded to delinearize " << *this << "\n"; dbgs() << "ArrayDecl[UnknownSize]" ; for (const SCEV *S : Sizes) dbgs() << "[" << *S << "]"; dbgs() << "\nArrayRef"; for (const SCEV * S : Subscripts) dbgs() << "[" << *S << "]"; dbgs() << "\n"; }; } } while (0) |
| 7626 | for (const SCEV *S : Sizes)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "succeeded to delinearize " << *this << "\n"; dbgs() << "ArrayDecl[UnknownSize]" ; for (const SCEV *S : Sizes) dbgs() << "[" << *S << "]"; dbgs() << "\nArrayRef"; for (const SCEV * S : Subscripts) dbgs() << "[" << *S << "]"; dbgs() << "\n"; }; } } while (0) |
| 7627 | dbgs() << "[" << *S << "]";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "succeeded to delinearize " << *this << "\n"; dbgs() << "ArrayDecl[UnknownSize]" ; for (const SCEV *S : Sizes) dbgs() << "[" << *S << "]"; dbgs() << "\nArrayRef"; for (const SCEV * S : Subscripts) dbgs() << "[" << *S << "]"; dbgs() << "\n"; }; } } while (0) |
| 7628 | |
| 7629 | dbgs() << "\nArrayRef";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "succeeded to delinearize " << *this << "\n"; dbgs() << "ArrayDecl[UnknownSize]" ; for (const SCEV *S : Sizes) dbgs() << "[" << *S << "]"; dbgs() << "\nArrayRef"; for (const SCEV * S : Subscripts) dbgs() << "[" << *S << "]"; dbgs() << "\n"; }; } } while (0) |
| 7630 | for (const SCEV *S : Subscripts)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "succeeded to delinearize " << *this << "\n"; dbgs() << "ArrayDecl[UnknownSize]" ; for (const SCEV *S : Sizes) dbgs() << "[" << *S << "]"; dbgs() << "\nArrayRef"; for (const SCEV * S : Subscripts) dbgs() << "[" << *S << "]"; dbgs() << "\n"; }; } } while (0) |
| 7631 | dbgs() << "[" << *S << "]";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "succeeded to delinearize " << *this << "\n"; dbgs() << "ArrayDecl[UnknownSize]" ; for (const SCEV *S : Sizes) dbgs() << "[" << *S << "]"; dbgs() << "\nArrayRef"; for (const SCEV * S : Subscripts) dbgs() << "[" << *S << "]"; dbgs() << "\n"; }; } } while (0) |
| 7632 | dbgs() << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "succeeded to delinearize " << *this << "\n"; dbgs() << "ArrayDecl[UnknownSize]" ; for (const SCEV *S : Sizes) dbgs() << "[" << *S << "]"; dbgs() << "\nArrayRef"; for (const SCEV * S : Subscripts) dbgs() << "[" << *S << "]"; dbgs() << "\n"; }; } } while (0) |
| 7633 | })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "succeeded to delinearize " << *this << "\n"; dbgs() << "ArrayDecl[UnknownSize]" ; for (const SCEV *S : Sizes) dbgs() << "[" << *S << "]"; dbgs() << "\nArrayRef"; for (const SCEV * S : Subscripts) dbgs() << "[" << *S << "]"; dbgs() << "\n"; }; } } while (0); |
| 7634 | } |
| 7635 | |
| 7636 | //===----------------------------------------------------------------------===// |
| 7637 | // SCEVCallbackVH Class Implementation |
| 7638 | //===----------------------------------------------------------------------===// |
| 7639 | |
| 7640 | void ScalarEvolution::SCEVCallbackVH::deleted() { |
| 7641 | assert(SE && "SCEVCallbackVH called with a null ScalarEvolution!")((SE && "SCEVCallbackVH called with a null ScalarEvolution!" ) ? static_cast<void> (0) : __assert_fail ("SE && \"SCEVCallbackVH called with a null ScalarEvolution!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 7641, __PRETTY_FUNCTION__)); |
| 7642 | if (PHINode *PN = dyn_cast<PHINode>(getValPtr())) |
| 7643 | SE->ConstantEvolutionLoopExitValue.erase(PN); |
| 7644 | SE->ValueExprMap.erase(getValPtr()); |
| 7645 | // this now dangles! |
| 7646 | } |
| 7647 | |
| 7648 | void ScalarEvolution::SCEVCallbackVH::allUsesReplacedWith(Value *V) { |
| 7649 | assert(SE && "SCEVCallbackVH called with a null ScalarEvolution!")((SE && "SCEVCallbackVH called with a null ScalarEvolution!" ) ? static_cast<void> (0) : __assert_fail ("SE && \"SCEVCallbackVH called with a null ScalarEvolution!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 7649, __PRETTY_FUNCTION__)); |
| 7650 | |
| 7651 | // Forget all the expressions associated with users of the old value, |
| 7652 | // so that future queries will recompute the expressions using the new |
| 7653 | // value. |
| 7654 | Value *Old = getValPtr(); |
| 7655 | SmallVector<User *, 16> Worklist(Old->user_begin(), Old->user_end()); |
| 7656 | SmallPtrSet<User *, 8> Visited; |
| 7657 | while (!Worklist.empty()) { |
| 7658 | User *U = Worklist.pop_back_val(); |
| 7659 | // Deleting the Old value will cause this to dangle. Postpone |
| 7660 | // that until everything else is done. |
| 7661 | if (U == Old) |
| 7662 | continue; |
| 7663 | if (!Visited.insert(U)) |
| 7664 | continue; |
| 7665 | if (PHINode *PN = dyn_cast<PHINode>(U)) |
| 7666 | SE->ConstantEvolutionLoopExitValue.erase(PN); |
| 7667 | SE->ValueExprMap.erase(U); |
| 7668 | Worklist.insert(Worklist.end(), U->user_begin(), U->user_end()); |
| 7669 | } |
| 7670 | // Delete the Old value. |
| 7671 | if (PHINode *PN = dyn_cast<PHINode>(Old)) |
| 7672 | SE->ConstantEvolutionLoopExitValue.erase(PN); |
| 7673 | SE->ValueExprMap.erase(Old); |
| 7674 | // this now dangles! |
| 7675 | } |
| 7676 | |
| 7677 | ScalarEvolution::SCEVCallbackVH::SCEVCallbackVH(Value *V, ScalarEvolution *se) |
| 7678 | : CallbackVH(V), SE(se) {} |
| 7679 | |
| 7680 | //===----------------------------------------------------------------------===// |
| 7681 | // ScalarEvolution Class Implementation |
| 7682 | //===----------------------------------------------------------------------===// |
| 7683 | |
| 7684 | ScalarEvolution::ScalarEvolution() |
| 7685 | : FunctionPass(ID), ValuesAtScopes(64), LoopDispositions(64), |
| 7686 | BlockDispositions(64), FirstUnknown(nullptr) { |
| 7687 | initializeScalarEvolutionPass(*PassRegistry::getPassRegistry()); |
| 7688 | } |
| 7689 | |
| 7690 | bool ScalarEvolution::runOnFunction(Function &F) { |
| 7691 | this->F = &F; |
| 7692 | AT = &getAnalysis<AssumptionTracker>(); |
| 7693 | LI = &getAnalysis<LoopInfo>(); |
| 7694 | DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>(); |
| 7695 | DL = DLP ? &DLP->getDataLayout() : nullptr; |
| 7696 | TLI = &getAnalysis<TargetLibraryInfo>(); |
| 7697 | DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree(); |
| 7698 | return false; |
| 7699 | } |
| 7700 | |
| 7701 | void ScalarEvolution::releaseMemory() { |
| 7702 | // Iterate through all the SCEVUnknown instances and call their |
| 7703 | // destructors, so that they release their references to their values. |
| 7704 | for (SCEVUnknown *U = FirstUnknown; U; U = U->Next) |
| 7705 | U->~SCEVUnknown(); |
| 7706 | FirstUnknown = nullptr; |
| 7707 | |
| 7708 | ValueExprMap.clear(); |
| 7709 | |
| 7710 | // Free any extra memory created for ExitNotTakenInfo in the unlikely event |
| 7711 | // that a loop had multiple computable exits. |
| 7712 | for (DenseMap<const Loop*, BackedgeTakenInfo>::iterator I = |
| 7713 | BackedgeTakenCounts.begin(), E = BackedgeTakenCounts.end(); |
| 7714 | I != E; ++I) { |
| 7715 | I->second.clear(); |
| 7716 | } |
| 7717 | |
| 7718 | assert(PendingLoopPredicates.empty() && "isImpliedCond garbage")((PendingLoopPredicates.empty() && "isImpliedCond garbage" ) ? static_cast<void> (0) : __assert_fail ("PendingLoopPredicates.empty() && \"isImpliedCond garbage\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 7718, __PRETTY_FUNCTION__)); |
| 7719 | |
| 7720 | BackedgeTakenCounts.clear(); |
| 7721 | ConstantEvolutionLoopExitValue.clear(); |
| 7722 | ValuesAtScopes.clear(); |
| 7723 | LoopDispositions.clear(); |
| 7724 | BlockDispositions.clear(); |
| 7725 | UnsignedRanges.clear(); |
| 7726 | SignedRanges.clear(); |
| 7727 | UniqueSCEVs.clear(); |
| 7728 | SCEVAllocator.Reset(); |
| 7729 | } |
| 7730 | |
| 7731 | void ScalarEvolution::getAnalysisUsage(AnalysisUsage &AU) const { |
| 7732 | AU.setPreservesAll(); |
| 7733 | AU.addRequired<AssumptionTracker>(); |
| 7734 | AU.addRequiredTransitive<LoopInfo>(); |
| 7735 | AU.addRequiredTransitive<DominatorTreeWrapperPass>(); |
| 7736 | AU.addRequired<TargetLibraryInfo>(); |
| 7737 | } |
| 7738 | |
| 7739 | bool ScalarEvolution::hasLoopInvariantBackedgeTakenCount(const Loop *L) { |
| 7740 | return !isa<SCEVCouldNotCompute>(getBackedgeTakenCount(L)); |
| 7741 | } |
| 7742 | |
| 7743 | static void PrintLoopInfo(raw_ostream &OS, ScalarEvolution *SE, |
| 7744 | const Loop *L) { |
| 7745 | // Print all inner loops first |
| 7746 | for (Loop::iterator I = L->begin(), E = L->end(); I != E; ++I) |
| 7747 | PrintLoopInfo(OS, SE, *I); |
| 7748 | |
| 7749 | OS << "Loop "; |
| 7750 | L->getHeader()->printAsOperand(OS, /*PrintType=*/false); |
| 7751 | OS << ": "; |
| 7752 | |
| 7753 | SmallVector<BasicBlock *, 8> ExitBlocks; |
| 7754 | L->getExitBlocks(ExitBlocks); |
| 7755 | if (ExitBlocks.size() != 1) |
| 7756 | OS << "<multiple exits> "; |
| 7757 | |
| 7758 | if (SE->hasLoopInvariantBackedgeTakenCount(L)) { |
| 7759 | OS << "backedge-taken count is " << *SE->getBackedgeTakenCount(L); |
| 7760 | } else { |
| 7761 | OS << "Unpredictable backedge-taken count. "; |
| 7762 | } |
| 7763 | |
| 7764 | OS << "\n" |
| 7765 | "Loop "; |
| 7766 | L->getHeader()->printAsOperand(OS, /*PrintType=*/false); |
| 7767 | OS << ": "; |
| 7768 | |
| 7769 | if (!isa<SCEVCouldNotCompute>(SE->getMaxBackedgeTakenCount(L))) { |
| 7770 | OS << "max backedge-taken count is " << *SE->getMaxBackedgeTakenCount(L); |
| 7771 | } else { |
| 7772 | OS << "Unpredictable max backedge-taken count. "; |
| 7773 | } |
| 7774 | |
| 7775 | OS << "\n"; |
| 7776 | } |
| 7777 | |
| 7778 | void ScalarEvolution::print(raw_ostream &OS, const Module *) const { |
| 7779 | // ScalarEvolution's implementation of the print method is to print |
| 7780 | // out SCEV values of all instructions that are interesting. Doing |
| 7781 | // this potentially causes it to create new SCEV objects though, |
| 7782 | // which technically conflicts with the const qualifier. This isn't |
| 7783 | // observable from outside the class though, so casting away the |
| 7784 | // const isn't dangerous. |
| 7785 | ScalarEvolution &SE = *const_cast<ScalarEvolution *>(this); |
| 7786 | |
| 7787 | OS << "Classifying expressions for: "; |
| 7788 | F->printAsOperand(OS, /*PrintType=*/false); |
| 7789 | OS << "\n"; |
| 7790 | for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I) |
| 7791 | if (isSCEVable(I->getType()) && !isa<CmpInst>(*I)) { |
| 7792 | OS << *I << '\n'; |
| 7793 | OS << " --> "; |
| 7794 | const SCEV *SV = SE.getSCEV(&*I); |
| 7795 | SV->print(OS); |
| 7796 | |
| 7797 | const Loop *L = LI->getLoopFor((*I).getParent()); |
| 7798 | |
| 7799 | const SCEV *AtUse = SE.getSCEVAtScope(SV, L); |
| 7800 | if (AtUse != SV) { |
| 7801 | OS << " --> "; |
| 7802 | AtUse->print(OS); |
| 7803 | } |
| 7804 | |
| 7805 | if (L) { |
| 7806 | OS << "\t\t" "Exits: "; |
| 7807 | const SCEV *ExitValue = SE.getSCEVAtScope(SV, L->getParentLoop()); |
| 7808 | if (!SE.isLoopInvariant(ExitValue, L)) { |
| 7809 | OS << "<<Unknown>>"; |
| 7810 | } else { |
| 7811 | OS << *ExitValue; |
| 7812 | } |
| 7813 | } |
| 7814 | |
| 7815 | OS << "\n"; |
| 7816 | } |
| 7817 | |
| 7818 | OS << "Determining loop execution counts for: "; |
| 7819 | F->printAsOperand(OS, /*PrintType=*/false); |
| 7820 | OS << "\n"; |
| 7821 | for (LoopInfo::iterator I = LI->begin(), E = LI->end(); I != E; ++I) |
| 7822 | PrintLoopInfo(OS, &SE, *I); |
| 7823 | } |
| 7824 | |
| 7825 | ScalarEvolution::LoopDisposition |
| 7826 | ScalarEvolution::getLoopDisposition(const SCEV *S, const Loop *L) { |
| 7827 | SmallVector<std::pair<const Loop *, LoopDisposition>, 2> &Values = LoopDispositions[S]; |
| 7828 | for (unsigned u = 0; u < Values.size(); u++) { |
| 7829 | if (Values[u].first == L) |
| 7830 | return Values[u].second; |
| 7831 | } |
| 7832 | Values.push_back(std::make_pair(L, LoopVariant)); |
| 7833 | LoopDisposition D = computeLoopDisposition(S, L); |
| 7834 | SmallVector<std::pair<const Loop *, LoopDisposition>, 2> &Values2 = LoopDispositions[S]; |
| 7835 | for (unsigned u = Values2.size(); u > 0; u--) { |
| 7836 | if (Values2[u - 1].first == L) { |
| 7837 | Values2[u - 1].second = D; |
| 7838 | break; |
| 7839 | } |
| 7840 | } |
| 7841 | return D; |
| 7842 | } |
| 7843 | |
| 7844 | ScalarEvolution::LoopDisposition |
| 7845 | ScalarEvolution::computeLoopDisposition(const SCEV *S, const Loop *L) { |
| 7846 | switch (static_cast<SCEVTypes>(S->getSCEVType())) { |
| 7847 | case scConstant: |
| 7848 | return LoopInvariant; |
| 7849 | case scTruncate: |
| 7850 | case scZeroExtend: |
| 7851 | case scSignExtend: |
| 7852 | return getLoopDisposition(cast<SCEVCastExpr>(S)->getOperand(), L); |
| 7853 | case scAddRecExpr: { |
| 7854 | const SCEVAddRecExpr *AR = cast<SCEVAddRecExpr>(S); |
| 7855 | |
| 7856 | // If L is the addrec's loop, it's computable. |
| 7857 | if (AR->getLoop() == L) |
| 7858 | return LoopComputable; |
| 7859 | |
| 7860 | // Add recurrences are never invariant in the function-body (null loop). |
| 7861 | if (!L) |
| 7862 | return LoopVariant; |
| 7863 | |
| 7864 | // This recurrence is variant w.r.t. L if L contains AR's loop. |
| 7865 | if (L->contains(AR->getLoop())) |
| 7866 | return LoopVariant; |
| 7867 | |
| 7868 | // This recurrence is invariant w.r.t. L if AR's loop contains L. |
| 7869 | if (AR->getLoop()->contains(L)) |
| 7870 | return LoopInvariant; |
| 7871 | |
| 7872 | // This recurrence is variant w.r.t. L if any of its operands |
| 7873 | // are variant. |
| 7874 | for (SCEVAddRecExpr::op_iterator I = AR->op_begin(), E = AR->op_end(); |
| 7875 | I != E; ++I) |
| 7876 | if (!isLoopInvariant(*I, L)) |
| 7877 | return LoopVariant; |
| 7878 | |
| 7879 | // Otherwise it's loop-invariant. |
| 7880 | return LoopInvariant; |
| 7881 | } |
| 7882 | case scAddExpr: |
| 7883 | case scMulExpr: |
| 7884 | case scUMaxExpr: |
| 7885 | case scSMaxExpr: { |
| 7886 | const SCEVNAryExpr *NAry = cast<SCEVNAryExpr>(S); |
| 7887 | bool HasVarying = false; |
| 7888 | for (SCEVNAryExpr::op_iterator I = NAry->op_begin(), E = NAry->op_end(); |
| 7889 | I != E; ++I) { |
| 7890 | LoopDisposition D = getLoopDisposition(*I, L); |
| 7891 | if (D == LoopVariant) |
| 7892 | return LoopVariant; |
| 7893 | if (D == LoopComputable) |
| 7894 | HasVarying = true; |
| 7895 | } |
| 7896 | return HasVarying ? LoopComputable : LoopInvariant; |
| 7897 | } |
| 7898 | case scUDivExpr: { |
| 7899 | const SCEVUDivExpr *UDiv = cast<SCEVUDivExpr>(S); |
| 7900 | LoopDisposition LD = getLoopDisposition(UDiv->getLHS(), L); |
| 7901 | if (LD == LoopVariant) |
| 7902 | return LoopVariant; |
| 7903 | LoopDisposition RD = getLoopDisposition(UDiv->getRHS(), L); |
| 7904 | if (RD == LoopVariant) |
| 7905 | return LoopVariant; |
| 7906 | return (LD == LoopInvariant && RD == LoopInvariant) ? |
| 7907 | LoopInvariant : LoopComputable; |
| 7908 | } |
| 7909 | case scUnknown: |
| 7910 | // All non-instruction values are loop invariant. All instructions are loop |
| 7911 | // invariant if they are not contained in the specified loop. |
| 7912 | // Instructions are never considered invariant in the function body |
| 7913 | // (null loop) because they are defined within the "loop". |
| 7914 | if (Instruction *I = dyn_cast<Instruction>(cast<SCEVUnknown>(S)->getValue())) |
| 7915 | return (L && !L->contains(I)) ? LoopInvariant : LoopVariant; |
| 7916 | return LoopInvariant; |
| 7917 | case scCouldNotCompute: |
| 7918 | llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!")::llvm::llvm_unreachable_internal("Attempt to use a SCEVCouldNotCompute object!" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 7918); |
| 7919 | } |
| 7920 | llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 7920); |
| 7921 | } |
| 7922 | |
| 7923 | bool ScalarEvolution::isLoopInvariant(const SCEV *S, const Loop *L) { |
| 7924 | return getLoopDisposition(S, L) == LoopInvariant; |
| 7925 | } |
| 7926 | |
| 7927 | bool ScalarEvolution::hasComputableLoopEvolution(const SCEV *S, const Loop *L) { |
| 7928 | return getLoopDisposition(S, L) == LoopComputable; |
| 7929 | } |
| 7930 | |
| 7931 | ScalarEvolution::BlockDisposition |
| 7932 | ScalarEvolution::getBlockDisposition(const SCEV *S, const BasicBlock *BB) { |
| 7933 | SmallVector<std::pair<const BasicBlock *, BlockDisposition>, 2> &Values = BlockDispositions[S]; |
| 7934 | for (unsigned u = 0; u < Values.size(); u++) { |
| 7935 | if (Values[u].first == BB) |
| 7936 | return Values[u].second; |
| 7937 | } |
| 7938 | Values.push_back(std::make_pair(BB, DoesNotDominateBlock)); |
| 7939 | BlockDisposition D = computeBlockDisposition(S, BB); |
| 7940 | SmallVector<std::pair<const BasicBlock *, BlockDisposition>, 2> &Values2 = BlockDispositions[S]; |
| 7941 | for (unsigned u = Values2.size(); u > 0; u--) { |
| 7942 | if (Values2[u - 1].first == BB) { |
| 7943 | Values2[u - 1].second = D; |
| 7944 | break; |
| 7945 | } |
| 7946 | } |
| 7947 | return D; |
| 7948 | } |
| 7949 | |
| 7950 | ScalarEvolution::BlockDisposition |
| 7951 | ScalarEvolution::computeBlockDisposition(const SCEV *S, const BasicBlock *BB) { |
| 7952 | switch (static_cast<SCEVTypes>(S->getSCEVType())) { |
| 7953 | case scConstant: |
| 7954 | return ProperlyDominatesBlock; |
| 7955 | case scTruncate: |
| 7956 | case scZeroExtend: |
| 7957 | case scSignExtend: |
| 7958 | return getBlockDisposition(cast<SCEVCastExpr>(S)->getOperand(), BB); |
| 7959 | case scAddRecExpr: { |
| 7960 | // This uses a "dominates" query instead of "properly dominates" query |
| 7961 | // to test for proper dominance too, because the instruction which |
| 7962 | // produces the addrec's value is a PHI, and a PHI effectively properly |
| 7963 | // dominates its entire containing block. |
| 7964 | const SCEVAddRecExpr *AR = cast<SCEVAddRecExpr>(S); |
| 7965 | if (!DT->dominates(AR->getLoop()->getHeader(), BB)) |
| 7966 | return DoesNotDominateBlock; |
| 7967 | } |
| 7968 | // FALL THROUGH into SCEVNAryExpr handling. |
| 7969 | case scAddExpr: |
| 7970 | case scMulExpr: |
| 7971 | case scUMaxExpr: |
| 7972 | case scSMaxExpr: { |
| 7973 | const SCEVNAryExpr *NAry = cast<SCEVNAryExpr>(S); |
| 7974 | bool Proper = true; |
| 7975 | for (SCEVNAryExpr::op_iterator I = NAry->op_begin(), E = NAry->op_end(); |
| 7976 | I != E; ++I) { |
| 7977 | BlockDisposition D = getBlockDisposition(*I, BB); |
| 7978 | if (D == DoesNotDominateBlock) |
| 7979 | return DoesNotDominateBlock; |
| 7980 | if (D == DominatesBlock) |
| 7981 | Proper = false; |
| 7982 | } |
| 7983 | return Proper ? ProperlyDominatesBlock : DominatesBlock; |
| 7984 | } |
| 7985 | case scUDivExpr: { |
| 7986 | const SCEVUDivExpr *UDiv = cast<SCEVUDivExpr>(S); |
| 7987 | const SCEV *LHS = UDiv->getLHS(), *RHS = UDiv->getRHS(); |
| 7988 | BlockDisposition LD = getBlockDisposition(LHS, BB); |
| 7989 | if (LD == DoesNotDominateBlock) |
| 7990 | return DoesNotDominateBlock; |
| 7991 | BlockDisposition RD = getBlockDisposition(RHS, BB); |
| 7992 | if (RD == DoesNotDominateBlock) |
| 7993 | return DoesNotDominateBlock; |
| 7994 | return (LD == ProperlyDominatesBlock && RD == ProperlyDominatesBlock) ? |
| 7995 | ProperlyDominatesBlock : DominatesBlock; |
| 7996 | } |
| 7997 | case scUnknown: |
| 7998 | if (Instruction *I = |
| 7999 | dyn_cast<Instruction>(cast<SCEVUnknown>(S)->getValue())) { |
| 8000 | if (I->getParent() == BB) |
| 8001 | return DominatesBlock; |
| 8002 | if (DT->properlyDominates(I->getParent(), BB)) |
| 8003 | return ProperlyDominatesBlock; |
| 8004 | return DoesNotDominateBlock; |
| 8005 | } |
| 8006 | return ProperlyDominatesBlock; |
| 8007 | case scCouldNotCompute: |
| 8008 | llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!")::llvm::llvm_unreachable_internal("Attempt to use a SCEVCouldNotCompute object!" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 8008); |
| 8009 | } |
| 8010 | llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 8010); |
| 8011 | } |
| 8012 | |
| 8013 | bool ScalarEvolution::dominates(const SCEV *S, const BasicBlock *BB) { |
| 8014 | return getBlockDisposition(S, BB) >= DominatesBlock; |
| 8015 | } |
| 8016 | |
| 8017 | bool ScalarEvolution::properlyDominates(const SCEV *S, const BasicBlock *BB) { |
| 8018 | return getBlockDisposition(S, BB) == ProperlyDominatesBlock; |
| 8019 | } |
| 8020 | |
| 8021 | namespace { |
| 8022 | // Search for a SCEV expression node within an expression tree. |
| 8023 | // Implements SCEVTraversal::Visitor. |
| 8024 | struct SCEVSearch { |
| 8025 | const SCEV *Node; |
| 8026 | bool IsFound; |
| 8027 | |
| 8028 | SCEVSearch(const SCEV *N): Node(N), IsFound(false) {} |
| 8029 | |
| 8030 | bool follow(const SCEV *S) { |
| 8031 | IsFound |= (S == Node); |
| 8032 | return !IsFound; |
| 8033 | } |
| 8034 | bool isDone() const { return IsFound; } |
| 8035 | }; |
| 8036 | } |
| 8037 | |
| 8038 | bool ScalarEvolution::hasOperand(const SCEV *S, const SCEV *Op) const { |
| 8039 | SCEVSearch Search(Op); |
| 8040 | visitAll(S, Search); |
| 8041 | return Search.IsFound; |
| 8042 | } |
| 8043 | |
| 8044 | void ScalarEvolution::forgetMemoizedResults(const SCEV *S) { |
| 8045 | ValuesAtScopes.erase(S); |
| 8046 | LoopDispositions.erase(S); |
| 8047 | BlockDispositions.erase(S); |
| 8048 | UnsignedRanges.erase(S); |
| 8049 | SignedRanges.erase(S); |
| 8050 | |
| 8051 | for (DenseMap<const Loop*, BackedgeTakenInfo>::iterator I = |
| 8052 | BackedgeTakenCounts.begin(), E = BackedgeTakenCounts.end(); I != E; ) { |
| 8053 | BackedgeTakenInfo &BEInfo = I->second; |
| 8054 | if (BEInfo.hasOperand(S, this)) { |
| 8055 | BEInfo.clear(); |
| 8056 | BackedgeTakenCounts.erase(I++); |
| 8057 | } |
| 8058 | else |
| 8059 | ++I; |
| 8060 | } |
| 8061 | } |
| 8062 | |
| 8063 | typedef DenseMap<const Loop *, std::string> VerifyMap; |
| 8064 | |
| 8065 | /// replaceSubString - Replaces all occurrences of From in Str with To. |
| 8066 | static void replaceSubString(std::string &Str, StringRef From, StringRef To) { |
| 8067 | size_t Pos = 0; |
| 8068 | while ((Pos = Str.find(From, Pos)) != std::string::npos) { |
| 8069 | Str.replace(Pos, From.size(), To.data(), To.size()); |
| 8070 | Pos += To.size(); |
| 8071 | } |
| 8072 | } |
| 8073 | |
| 8074 | /// getLoopBackedgeTakenCounts - Helper method for verifyAnalysis. |
| 8075 | static void |
| 8076 | getLoopBackedgeTakenCounts(Loop *L, VerifyMap &Map, ScalarEvolution &SE) { |
| 8077 | for (Loop::reverse_iterator I = L->rbegin(), E = L->rend(); I != E; ++I) { |
| 8078 | getLoopBackedgeTakenCounts(*I, Map, SE); // recurse. |
| 8079 | |
| 8080 | std::string &S = Map[L]; |
| 8081 | if (S.empty()) { |
| 8082 | raw_string_ostream OS(S); |
| 8083 | SE.getBackedgeTakenCount(L)->print(OS); |
| 8084 | |
| 8085 | // false and 0 are semantically equivalent. This can happen in dead loops. |
| 8086 | replaceSubString(OS.str(), "false", "0"); |
| 8087 | // Remove wrap flags, their use in SCEV is highly fragile. |
| 8088 | // FIXME: Remove this when SCEV gets smarter about them. |
| 8089 | replaceSubString(OS.str(), "<nw>", ""); |
| 8090 | replaceSubString(OS.str(), "<nsw>", ""); |
| 8091 | replaceSubString(OS.str(), "<nuw>", ""); |
| 8092 | } |
| 8093 | } |
| 8094 | } |
| 8095 | |
| 8096 | void ScalarEvolution::verifyAnalysis() const { |
| 8097 | if (!VerifySCEV) |
| 8098 | return; |
| 8099 | |
| 8100 | ScalarEvolution &SE = *const_cast<ScalarEvolution *>(this); |
| 8101 | |
| 8102 | // Gather stringified backedge taken counts for all loops using SCEV's caches. |
| 8103 | // FIXME: It would be much better to store actual values instead of strings, |
| 8104 | // but SCEV pointers will change if we drop the caches. |
| 8105 | VerifyMap BackedgeDumpsOld, BackedgeDumpsNew; |
| 8106 | for (LoopInfo::reverse_iterator I = LI->rbegin(), E = LI->rend(); I != E; ++I) |
| 8107 | getLoopBackedgeTakenCounts(*I, BackedgeDumpsOld, SE); |
| 8108 | |
| 8109 | // Gather stringified backedge taken counts for all loops without using |
| 8110 | // SCEV's caches. |
| 8111 | SE.releaseMemory(); |
| 8112 | for (LoopInfo::reverse_iterator I = LI->rbegin(), E = LI->rend(); I != E; ++I) |
| 8113 | getLoopBackedgeTakenCounts(*I, BackedgeDumpsNew, SE); |
| 8114 | |
| 8115 | // Now compare whether they're the same with and without caches. This allows |
| 8116 | // verifying that no pass changed the cache. |
| 8117 | assert(BackedgeDumpsOld.size() == BackedgeDumpsNew.size() &&((BackedgeDumpsOld.size() == BackedgeDumpsNew.size() && "New loops suddenly appeared!") ? static_cast<void> (0 ) : __assert_fail ("BackedgeDumpsOld.size() == BackedgeDumpsNew.size() && \"New loops suddenly appeared!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 8118, __PRETTY_FUNCTION__)) |
| 8118 | "New loops suddenly appeared!")((BackedgeDumpsOld.size() == BackedgeDumpsNew.size() && "New loops suddenly appeared!") ? static_cast<void> (0 ) : __assert_fail ("BackedgeDumpsOld.size() == BackedgeDumpsNew.size() && \"New loops suddenly appeared!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 8118, __PRETTY_FUNCTION__)); |
| 8119 | |
| 8120 | for (VerifyMap::iterator OldI = BackedgeDumpsOld.begin(), |
| 8121 | OldE = BackedgeDumpsOld.end(), |
| 8122 | NewI = BackedgeDumpsNew.begin(); |
| 8123 | OldI != OldE; ++OldI, ++NewI) { |
| 8124 | assert(OldI->first == NewI->first && "Loop order changed!")((OldI->first == NewI->first && "Loop order changed!" ) ? static_cast<void> (0) : __assert_fail ("OldI->first == NewI->first && \"Loop order changed!\"" , "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn220848/lib/Analysis/ScalarEvolution.cpp" , 8124, __PRETTY_FUNCTION__)); |
| 8125 | |
| 8126 | // Compare the stringified SCEVs. We don't care if undef backedgetaken count |
| 8127 | // changes. |
| 8128 | // FIXME: We currently ignore SCEV changes from/to CouldNotCompute. This |
| 8129 | // means that a pass is buggy or SCEV has to learn a new pattern but is |
| 8130 | // usually not harmful. |
| 8131 | if (OldI->second != NewI->second && |
| 8132 | OldI->second.find("undef") == std::string::npos && |
| 8133 | NewI->second.find("undef") == std::string::npos && |
| 8134 | OldI->second != "***COULDNOTCOMPUTE***" && |
| 8135 | NewI->second != "***COULDNOTCOMPUTE***") { |
| 8136 | dbgs() << "SCEVValidator: SCEV for loop '" |
| 8137 | << OldI->first->getHeader()->getName() |
| 8138 | << "' changed from '" << OldI->second |
| 8139 | << "' to '" << NewI->second << "'!\n"; |
| 8140 | std::abort(); |
| 8141 | } |
| 8142 | } |
| 8143 | |
| 8144 | // TODO: Verify more things. |
| 8145 | } |