| File: | llvm/lib/Analysis/ScalarEvolution.cpp |
| Warning: | line 10169, column 35 Called C++ object pointer is null |
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| 1 | //===- ScalarEvolution.cpp - Scalar Evolution Analysis --------------------===// |
| 2 | // |
| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| 4 | // See https://llvm.org/LICENSE.txt for license information. |
| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| 6 | // |
| 7 | //===----------------------------------------------------------------------===// |
| 8 | // |
| 9 | // This file contains the implementation of the scalar evolution analysis |
| 10 | // engine, which is used primarily to analyze expressions involving induction |
| 11 | // variables in loops. |
| 12 | // |
| 13 | // There are several aspects to this library. First is the representation of |
| 14 | // scalar expressions, which are represented as subclasses of the SCEV class. |
| 15 | // These classes are used to represent certain types of subexpressions that we |
| 16 | // can handle. We only create one SCEV of a particular shape, so |
| 17 | // pointer-comparisons for equality are legal. |
| 18 | // |
| 19 | // One important aspect of the SCEV objects is that they are never cyclic, even |
| 20 | // if there is a cycle in the dataflow for an expression (ie, a PHI node). If |
| 21 | // the PHI node is one of the idioms that we can represent (e.g., a polynomial |
| 22 | // recurrence) then we represent it directly as a recurrence node, otherwise we |
| 23 | // represent it as a SCEVUnknown node. |
| 24 | // |
| 25 | // In addition to being able to represent expressions of various types, we also |
| 26 | // have folders that are used to build the *canonical* representation for a |
| 27 | // particular expression. These folders are capable of using a variety of |
| 28 | // rewrite rules to simplify the expressions. |
| 29 | // |
| 30 | // Once the folders are defined, we can implement the more interesting |
| 31 | // higher-level code, such as the code that recognizes PHI nodes of various |
| 32 | // types, computes the execution count of a loop, etc. |
| 33 | // |
| 34 | // TODO: We should use these routines and value representations to implement |
| 35 | // dependence analysis! |
| 36 | // |
| 37 | //===----------------------------------------------------------------------===// |
| 38 | // |
| 39 | // There are several good references for the techniques used in this analysis. |
| 40 | // |
| 41 | // Chains of recurrences -- a method to expedite the evaluation |
| 42 | // of closed-form functions |
| 43 | // Olaf Bachmann, Paul S. Wang, Eugene V. Zima |
| 44 | // |
| 45 | // On computational properties of chains of recurrences |
| 46 | // Eugene V. Zima |
| 47 | // |
| 48 | // Symbolic Evaluation of Chains of Recurrences for Loop Optimization |
| 49 | // Robert A. van Engelen |
| 50 | // |
| 51 | // Efficient Symbolic Analysis for Optimizing Compilers |
| 52 | // Robert A. van Engelen |
| 53 | // |
| 54 | // Using the chains of recurrences algebra for data dependence testing and |
| 55 | // induction variable substitution |
| 56 | // MS Thesis, Johnie Birch |
| 57 | // |
| 58 | //===----------------------------------------------------------------------===// |
| 59 | |
| 60 | #include "llvm/Analysis/ScalarEvolution.h" |
| 61 | #include "llvm/ADT/APInt.h" |
| 62 | #include "llvm/ADT/ArrayRef.h" |
| 63 | #include "llvm/ADT/DenseMap.h" |
| 64 | #include "llvm/ADT/DepthFirstIterator.h" |
| 65 | #include "llvm/ADT/EquivalenceClasses.h" |
| 66 | #include "llvm/ADT/FoldingSet.h" |
| 67 | #include "llvm/ADT/None.h" |
| 68 | #include "llvm/ADT/Optional.h" |
| 69 | #include "llvm/ADT/STLExtras.h" |
| 70 | #include "llvm/ADT/ScopeExit.h" |
| 71 | #include "llvm/ADT/Sequence.h" |
| 72 | #include "llvm/ADT/SetVector.h" |
| 73 | #include "llvm/ADT/SmallPtrSet.h" |
| 74 | #include "llvm/ADT/SmallSet.h" |
| 75 | #include "llvm/ADT/SmallVector.h" |
| 76 | #include "llvm/ADT/Statistic.h" |
| 77 | #include "llvm/ADT/StringRef.h" |
| 78 | #include "llvm/Analysis/AssumptionCache.h" |
| 79 | #include "llvm/Analysis/ConstantFolding.h" |
| 80 | #include "llvm/Analysis/InstructionSimplify.h" |
| 81 | #include "llvm/Analysis/LoopInfo.h" |
| 82 | #include "llvm/Analysis/ScalarEvolutionDivision.h" |
| 83 | #include "llvm/Analysis/ScalarEvolutionExpressions.h" |
| 84 | #include "llvm/Analysis/TargetLibraryInfo.h" |
| 85 | #include "llvm/Analysis/ValueTracking.h" |
| 86 | #include "llvm/Config/llvm-config.h" |
| 87 | #include "llvm/IR/Argument.h" |
| 88 | #include "llvm/IR/BasicBlock.h" |
| 89 | #include "llvm/IR/CFG.h" |
| 90 | #include "llvm/IR/Constant.h" |
| 91 | #include "llvm/IR/ConstantRange.h" |
| 92 | #include "llvm/IR/Constants.h" |
| 93 | #include "llvm/IR/DataLayout.h" |
| 94 | #include "llvm/IR/DerivedTypes.h" |
| 95 | #include "llvm/IR/Dominators.h" |
| 96 | #include "llvm/IR/Function.h" |
| 97 | #include "llvm/IR/GlobalAlias.h" |
| 98 | #include "llvm/IR/GlobalValue.h" |
| 99 | #include "llvm/IR/GlobalVariable.h" |
| 100 | #include "llvm/IR/InstIterator.h" |
| 101 | #include "llvm/IR/InstrTypes.h" |
| 102 | #include "llvm/IR/Instruction.h" |
| 103 | #include "llvm/IR/Instructions.h" |
| 104 | #include "llvm/IR/IntrinsicInst.h" |
| 105 | #include "llvm/IR/Intrinsics.h" |
| 106 | #include "llvm/IR/LLVMContext.h" |
| 107 | #include "llvm/IR/Metadata.h" |
| 108 | #include "llvm/IR/Operator.h" |
| 109 | #include "llvm/IR/PatternMatch.h" |
| 110 | #include "llvm/IR/Type.h" |
| 111 | #include "llvm/IR/Use.h" |
| 112 | #include "llvm/IR/User.h" |
| 113 | #include "llvm/IR/Value.h" |
| 114 | #include "llvm/IR/Verifier.h" |
| 115 | #include "llvm/InitializePasses.h" |
| 116 | #include "llvm/Pass.h" |
| 117 | #include "llvm/Support/Casting.h" |
| 118 | #include "llvm/Support/CommandLine.h" |
| 119 | #include "llvm/Support/Compiler.h" |
| 120 | #include "llvm/Support/Debug.h" |
| 121 | #include "llvm/Support/ErrorHandling.h" |
| 122 | #include "llvm/Support/KnownBits.h" |
| 123 | #include "llvm/Support/SaveAndRestore.h" |
| 124 | #include "llvm/Support/raw_ostream.h" |
| 125 | #include <algorithm> |
| 126 | #include <cassert> |
| 127 | #include <climits> |
| 128 | #include <cstddef> |
| 129 | #include <cstdint> |
| 130 | #include <cstdlib> |
| 131 | #include <map> |
| 132 | #include <memory> |
| 133 | #include <tuple> |
| 134 | #include <utility> |
| 135 | #include <vector> |
| 136 | |
| 137 | using namespace llvm; |
| 138 | using namespace PatternMatch; |
| 139 | |
| 140 | #define DEBUG_TYPE"scalar-evolution" "scalar-evolution" |
| 141 | |
| 142 | STATISTIC(NumArrayLenItCounts,static llvm::Statistic NumArrayLenItCounts = {"scalar-evolution" , "NumArrayLenItCounts", "Number of trip counts computed with array length" } |
| 143 | "Number of trip counts computed with array length")static llvm::Statistic NumArrayLenItCounts = {"scalar-evolution" , "NumArrayLenItCounts", "Number of trip counts computed with array length" }; |
| 144 | STATISTIC(NumTripCountsComputed,static llvm::Statistic NumTripCountsComputed = {"scalar-evolution" , "NumTripCountsComputed", "Number of loops with predictable loop counts" } |
| 145 | "Number of loops with predictable loop counts")static llvm::Statistic NumTripCountsComputed = {"scalar-evolution" , "NumTripCountsComputed", "Number of loops with predictable loop counts" }; |
| 146 | STATISTIC(NumTripCountsNotComputed,static llvm::Statistic NumTripCountsNotComputed = {"scalar-evolution" , "NumTripCountsNotComputed", "Number of loops without predictable loop counts" } |
| 147 | "Number of loops without predictable loop counts")static llvm::Statistic NumTripCountsNotComputed = {"scalar-evolution" , "NumTripCountsNotComputed", "Number of loops without predictable loop counts" }; |
| 148 | STATISTIC(NumBruteForceTripCountsComputed,static llvm::Statistic NumBruteForceTripCountsComputed = {"scalar-evolution" , "NumBruteForceTripCountsComputed", "Number of loops with trip counts computed by force" } |
| 149 | "Number of loops with trip counts computed by force")static llvm::Statistic NumBruteForceTripCountsComputed = {"scalar-evolution" , "NumBruteForceTripCountsComputed", "Number of loops with trip counts computed by force" }; |
| 150 | |
| 151 | static cl::opt<unsigned> |
| 152 | MaxBruteForceIterations("scalar-evolution-max-iterations", cl::ReallyHidden, |
| 153 | cl::ZeroOrMore, |
| 154 | cl::desc("Maximum number of iterations SCEV will " |
| 155 | "symbolically execute a constant " |
| 156 | "derived loop"), |
| 157 | cl::init(100)); |
| 158 | |
| 159 | // FIXME: Enable this with EXPENSIVE_CHECKS when the test suite is clean. |
| 160 | static cl::opt<bool> VerifySCEV( |
| 161 | "verify-scev", cl::Hidden, |
| 162 | cl::desc("Verify ScalarEvolution's backedge taken counts (slow)")); |
| 163 | static cl::opt<bool> VerifySCEVStrict( |
| 164 | "verify-scev-strict", cl::Hidden, |
| 165 | cl::desc("Enable stricter verification with -verify-scev is passed")); |
| 166 | static cl::opt<bool> |
| 167 | VerifySCEVMap("verify-scev-maps", cl::Hidden, |
| 168 | cl::desc("Verify no dangling value in ScalarEvolution's " |
| 169 | "ExprValueMap (slow)")); |
| 170 | |
| 171 | static cl::opt<bool> VerifyIR( |
| 172 | "scev-verify-ir", cl::Hidden, |
| 173 | cl::desc("Verify IR correctness when making sensitive SCEV queries (slow)"), |
| 174 | cl::init(false)); |
| 175 | |
| 176 | static cl::opt<unsigned> MulOpsInlineThreshold( |
| 177 | "scev-mulops-inline-threshold", cl::Hidden, |
| 178 | cl::desc("Threshold for inlining multiplication operands into a SCEV"), |
| 179 | cl::init(32)); |
| 180 | |
| 181 | static cl::opt<unsigned> AddOpsInlineThreshold( |
| 182 | "scev-addops-inline-threshold", cl::Hidden, |
| 183 | cl::desc("Threshold for inlining addition operands into a SCEV"), |
| 184 | cl::init(500)); |
| 185 | |
| 186 | static cl::opt<unsigned> MaxSCEVCompareDepth( |
| 187 | "scalar-evolution-max-scev-compare-depth", cl::Hidden, |
| 188 | cl::desc("Maximum depth of recursive SCEV complexity comparisons"), |
| 189 | cl::init(32)); |
| 190 | |
| 191 | static cl::opt<unsigned> MaxSCEVOperationsImplicationDepth( |
| 192 | "scalar-evolution-max-scev-operations-implication-depth", cl::Hidden, |
| 193 | cl::desc("Maximum depth of recursive SCEV operations implication analysis"), |
| 194 | cl::init(2)); |
| 195 | |
| 196 | static cl::opt<unsigned> MaxValueCompareDepth( |
| 197 | "scalar-evolution-max-value-compare-depth", cl::Hidden, |
| 198 | cl::desc("Maximum depth of recursive value complexity comparisons"), |
| 199 | cl::init(2)); |
| 200 | |
| 201 | static cl::opt<unsigned> |
| 202 | MaxArithDepth("scalar-evolution-max-arith-depth", cl::Hidden, |
| 203 | cl::desc("Maximum depth of recursive arithmetics"), |
| 204 | cl::init(32)); |
| 205 | |
| 206 | static cl::opt<unsigned> MaxConstantEvolvingDepth( |
| 207 | "scalar-evolution-max-constant-evolving-depth", cl::Hidden, |
| 208 | cl::desc("Maximum depth of recursive constant evolving"), cl::init(32)); |
| 209 | |
| 210 | static cl::opt<unsigned> |
| 211 | MaxCastDepth("scalar-evolution-max-cast-depth", cl::Hidden, |
| 212 | cl::desc("Maximum depth of recursive SExt/ZExt/Trunc"), |
| 213 | cl::init(8)); |
| 214 | |
| 215 | static cl::opt<unsigned> |
| 216 | MaxAddRecSize("scalar-evolution-max-add-rec-size", cl::Hidden, |
| 217 | cl::desc("Max coefficients in AddRec during evolving"), |
| 218 | cl::init(8)); |
| 219 | |
| 220 | static cl::opt<unsigned> |
| 221 | HugeExprThreshold("scalar-evolution-huge-expr-threshold", cl::Hidden, |
| 222 | cl::desc("Size of the expression which is considered huge"), |
| 223 | cl::init(4096)); |
| 224 | |
| 225 | static cl::opt<bool> |
| 226 | ClassifyExpressions("scalar-evolution-classify-expressions", |
| 227 | cl::Hidden, cl::init(true), |
| 228 | cl::desc("When printing analysis, include information on every instruction")); |
| 229 | |
| 230 | static cl::opt<bool> UseExpensiveRangeSharpening( |
| 231 | "scalar-evolution-use-expensive-range-sharpening", cl::Hidden, |
| 232 | cl::init(false), |
| 233 | cl::desc("Use more powerful methods of sharpening expression ranges. May " |
| 234 | "be costly in terms of compile time")); |
| 235 | |
| 236 | //===----------------------------------------------------------------------===// |
| 237 | // SCEV class definitions |
| 238 | //===----------------------------------------------------------------------===// |
| 239 | |
| 240 | //===----------------------------------------------------------------------===// |
| 241 | // Implementation of the SCEV class. |
| 242 | // |
| 243 | |
| 244 | #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) |
| 245 | LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void SCEV::dump() const { |
| 246 | print(dbgs()); |
| 247 | dbgs() << '\n'; |
| 248 | } |
| 249 | #endif |
| 250 | |
| 251 | void SCEV::print(raw_ostream &OS) const { |
| 252 | switch (getSCEVType()) { |
| 253 | case scConstant: |
| 254 | cast<SCEVConstant>(this)->getValue()->printAsOperand(OS, false); |
| 255 | return; |
| 256 | case scPtrToInt: { |
| 257 | const SCEVPtrToIntExpr *PtrToInt = cast<SCEVPtrToIntExpr>(this); |
| 258 | const SCEV *Op = PtrToInt->getOperand(); |
| 259 | OS << "(ptrtoint " << *Op->getType() << " " << *Op << " to " |
| 260 | << *PtrToInt->getType() << ")"; |
| 261 | return; |
| 262 | } |
| 263 | case scTruncate: { |
| 264 | const SCEVTruncateExpr *Trunc = cast<SCEVTruncateExpr>(this); |
| 265 | const SCEV *Op = Trunc->getOperand(); |
| 266 | OS << "(trunc " << *Op->getType() << " " << *Op << " to " |
| 267 | << *Trunc->getType() << ")"; |
| 268 | return; |
| 269 | } |
| 270 | case scZeroExtend: { |
| 271 | const SCEVZeroExtendExpr *ZExt = cast<SCEVZeroExtendExpr>(this); |
| 272 | const SCEV *Op = ZExt->getOperand(); |
| 273 | OS << "(zext " << *Op->getType() << " " << *Op << " to " |
| 274 | << *ZExt->getType() << ")"; |
| 275 | return; |
| 276 | } |
| 277 | case scSignExtend: { |
| 278 | const SCEVSignExtendExpr *SExt = cast<SCEVSignExtendExpr>(this); |
| 279 | const SCEV *Op = SExt->getOperand(); |
| 280 | OS << "(sext " << *Op->getType() << " " << *Op << " to " |
| 281 | << *SExt->getType() << ")"; |
| 282 | return; |
| 283 | } |
| 284 | case scAddRecExpr: { |
| 285 | const SCEVAddRecExpr *AR = cast<SCEVAddRecExpr>(this); |
| 286 | OS << "{" << *AR->getOperand(0); |
| 287 | for (unsigned i = 1, e = AR->getNumOperands(); i != e; ++i) |
| 288 | OS << ",+," << *AR->getOperand(i); |
| 289 | OS << "}<"; |
| 290 | if (AR->hasNoUnsignedWrap()) |
| 291 | OS << "nuw><"; |
| 292 | if (AR->hasNoSignedWrap()) |
| 293 | OS << "nsw><"; |
| 294 | if (AR->hasNoSelfWrap() && |
| 295 | !AR->getNoWrapFlags((NoWrapFlags)(FlagNUW | FlagNSW))) |
| 296 | OS << "nw><"; |
| 297 | AR->getLoop()->getHeader()->printAsOperand(OS, /*PrintType=*/false); |
| 298 | OS << ">"; |
| 299 | return; |
| 300 | } |
| 301 | case scAddExpr: |
| 302 | case scMulExpr: |
| 303 | case scUMaxExpr: |
| 304 | case scSMaxExpr: |
| 305 | case scUMinExpr: |
| 306 | case scSMinExpr: { |
| 307 | const SCEVNAryExpr *NAry = cast<SCEVNAryExpr>(this); |
| 308 | const char *OpStr = nullptr; |
| 309 | switch (NAry->getSCEVType()) { |
| 310 | case scAddExpr: OpStr = " + "; break; |
| 311 | case scMulExpr: OpStr = " * "; break; |
| 312 | case scUMaxExpr: OpStr = " umax "; break; |
| 313 | case scSMaxExpr: OpStr = " smax "; break; |
| 314 | case scUMinExpr: |
| 315 | OpStr = " umin "; |
| 316 | break; |
| 317 | case scSMinExpr: |
| 318 | OpStr = " smin "; |
| 319 | break; |
| 320 | default: |
| 321 | llvm_unreachable("There are no other nary expression types.")::llvm::llvm_unreachable_internal("There are no other nary expression types." , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 321); |
| 322 | } |
| 323 | OS << "("; |
| 324 | ListSeparator LS(OpStr); |
| 325 | for (const SCEV *Op : NAry->operands()) |
| 326 | OS << LS << *Op; |
| 327 | OS << ")"; |
| 328 | switch (NAry->getSCEVType()) { |
| 329 | case scAddExpr: |
| 330 | case scMulExpr: |
| 331 | if (NAry->hasNoUnsignedWrap()) |
| 332 | OS << "<nuw>"; |
| 333 | if (NAry->hasNoSignedWrap()) |
| 334 | OS << "<nsw>"; |
| 335 | break; |
| 336 | default: |
| 337 | // Nothing to print for other nary expressions. |
| 338 | break; |
| 339 | } |
| 340 | return; |
| 341 | } |
| 342 | case scUDivExpr: { |
| 343 | const SCEVUDivExpr *UDiv = cast<SCEVUDivExpr>(this); |
| 344 | OS << "(" << *UDiv->getLHS() << " /u " << *UDiv->getRHS() << ")"; |
| 345 | return; |
| 346 | } |
| 347 | case scUnknown: { |
| 348 | const SCEVUnknown *U = cast<SCEVUnknown>(this); |
| 349 | Type *AllocTy; |
| 350 | if (U->isSizeOf(AllocTy)) { |
| 351 | OS << "sizeof(" << *AllocTy << ")"; |
| 352 | return; |
| 353 | } |
| 354 | if (U->isAlignOf(AllocTy)) { |
| 355 | OS << "alignof(" << *AllocTy << ")"; |
| 356 | return; |
| 357 | } |
| 358 | |
| 359 | Type *CTy; |
| 360 | Constant *FieldNo; |
| 361 | if (U->isOffsetOf(CTy, FieldNo)) { |
| 362 | OS << "offsetof(" << *CTy << ", "; |
| 363 | FieldNo->printAsOperand(OS, false); |
| 364 | OS << ")"; |
| 365 | return; |
| 366 | } |
| 367 | |
| 368 | // Otherwise just print it normally. |
| 369 | U->getValue()->printAsOperand(OS, false); |
| 370 | return; |
| 371 | } |
| 372 | case scCouldNotCompute: |
| 373 | OS << "***COULDNOTCOMPUTE***"; |
| 374 | return; |
| 375 | } |
| 376 | llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 376); |
| 377 | } |
| 378 | |
| 379 | Type *SCEV::getType() const { |
| 380 | switch (getSCEVType()) { |
| 381 | case scConstant: |
| 382 | return cast<SCEVConstant>(this)->getType(); |
| 383 | case scPtrToInt: |
| 384 | case scTruncate: |
| 385 | case scZeroExtend: |
| 386 | case scSignExtend: |
| 387 | return cast<SCEVCastExpr>(this)->getType(); |
| 388 | case scAddRecExpr: |
| 389 | case scMulExpr: |
| 390 | case scUMaxExpr: |
| 391 | case scSMaxExpr: |
| 392 | case scUMinExpr: |
| 393 | case scSMinExpr: |
| 394 | return cast<SCEVNAryExpr>(this)->getType(); |
| 395 | case scAddExpr: |
| 396 | return cast<SCEVAddExpr>(this)->getType(); |
| 397 | case scUDivExpr: |
| 398 | return cast<SCEVUDivExpr>(this)->getType(); |
| 399 | case scUnknown: |
| 400 | return cast<SCEVUnknown>(this)->getType(); |
| 401 | case scCouldNotCompute: |
| 402 | llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!")::llvm::llvm_unreachable_internal("Attempt to use a SCEVCouldNotCompute object!" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 402); |
| 403 | } |
| 404 | llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 404); |
| 405 | } |
| 406 | |
| 407 | bool SCEV::isZero() const { |
| 408 | if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this)) |
| 409 | return SC->getValue()->isZero(); |
| 410 | return false; |
| 411 | } |
| 412 | |
| 413 | bool SCEV::isOne() const { |
| 414 | if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this)) |
| 415 | return SC->getValue()->isOne(); |
| 416 | return false; |
| 417 | } |
| 418 | |
| 419 | bool SCEV::isAllOnesValue() const { |
| 420 | if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this)) |
| 421 | return SC->getValue()->isMinusOne(); |
| 422 | return false; |
| 423 | } |
| 424 | |
| 425 | bool SCEV::isNonConstantNegative() const { |
| 426 | const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(this); |
| 427 | if (!Mul) return false; |
| 428 | |
| 429 | // If there is a constant factor, it will be first. |
| 430 | const SCEVConstant *SC = dyn_cast<SCEVConstant>(Mul->getOperand(0)); |
| 431 | if (!SC) return false; |
| 432 | |
| 433 | // Return true if the value is negative, this matches things like (-42 * V). |
| 434 | return SC->getAPInt().isNegative(); |
| 435 | } |
| 436 | |
| 437 | SCEVCouldNotCompute::SCEVCouldNotCompute() : |
| 438 | SCEV(FoldingSetNodeIDRef(), scCouldNotCompute, 0) {} |
| 439 | |
| 440 | bool SCEVCouldNotCompute::classof(const SCEV *S) { |
| 441 | return S->getSCEVType() == scCouldNotCompute; |
| 442 | } |
| 443 | |
| 444 | const SCEV *ScalarEvolution::getConstant(ConstantInt *V) { |
| 445 | FoldingSetNodeID ID; |
| 446 | ID.AddInteger(scConstant); |
| 447 | ID.AddPointer(V); |
| 448 | void *IP = nullptr; |
| 449 | if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S; |
| 450 | SCEV *S = new (SCEVAllocator) SCEVConstant(ID.Intern(SCEVAllocator), V); |
| 451 | UniqueSCEVs.InsertNode(S, IP); |
| 452 | return S; |
| 453 | } |
| 454 | |
| 455 | const SCEV *ScalarEvolution::getConstant(const APInt &Val) { |
| 456 | return getConstant(ConstantInt::get(getContext(), Val)); |
| 457 | } |
| 458 | |
| 459 | const SCEV * |
| 460 | ScalarEvolution::getConstant(Type *Ty, uint64_t V, bool isSigned) { |
| 461 | IntegerType *ITy = cast<IntegerType>(getEffectiveSCEVType(Ty)); |
| 462 | return getConstant(ConstantInt::get(ITy, V, isSigned)); |
| 463 | } |
| 464 | |
| 465 | SCEVCastExpr::SCEVCastExpr(const FoldingSetNodeIDRef ID, SCEVTypes SCEVTy, |
| 466 | const SCEV *op, Type *ty) |
| 467 | : SCEV(ID, SCEVTy, computeExpressionSize(op)), Ty(ty) { |
| 468 | Operands[0] = op; |
| 469 | } |
| 470 | |
| 471 | SCEVPtrToIntExpr::SCEVPtrToIntExpr(const FoldingSetNodeIDRef ID, const SCEV *Op, |
| 472 | Type *ITy) |
| 473 | : SCEVCastExpr(ID, scPtrToInt, Op, ITy) { |
| 474 | assert(getOperand()->getType()->isPointerTy() && Ty->isIntegerTy() &&(static_cast <bool> (getOperand()->getType()->isPointerTy () && Ty->isIntegerTy() && "Must be a non-bit-width-changing pointer-to-integer cast!" ) ? void (0) : __assert_fail ("getOperand()->getType()->isPointerTy() && Ty->isIntegerTy() && \"Must be a non-bit-width-changing pointer-to-integer cast!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 475, __extension__ __PRETTY_FUNCTION__)) |
| 475 | "Must be a non-bit-width-changing pointer-to-integer cast!")(static_cast <bool> (getOperand()->getType()->isPointerTy () && Ty->isIntegerTy() && "Must be a non-bit-width-changing pointer-to-integer cast!" ) ? void (0) : __assert_fail ("getOperand()->getType()->isPointerTy() && Ty->isIntegerTy() && \"Must be a non-bit-width-changing pointer-to-integer cast!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 475, __extension__ __PRETTY_FUNCTION__)); |
| 476 | } |
| 477 | |
| 478 | SCEVIntegralCastExpr::SCEVIntegralCastExpr(const FoldingSetNodeIDRef ID, |
| 479 | SCEVTypes SCEVTy, const SCEV *op, |
| 480 | Type *ty) |
| 481 | : SCEVCastExpr(ID, SCEVTy, op, ty) {} |
| 482 | |
| 483 | SCEVTruncateExpr::SCEVTruncateExpr(const FoldingSetNodeIDRef ID, const SCEV *op, |
| 484 | Type *ty) |
| 485 | : SCEVIntegralCastExpr(ID, scTruncate, op, ty) { |
| 486 | assert(getOperand()->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&(static_cast <bool> (getOperand()->getType()->isIntOrPtrTy () && Ty->isIntOrPtrTy() && "Cannot truncate non-integer value!" ) ? void (0) : __assert_fail ("getOperand()->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot truncate non-integer value!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 487, __extension__ __PRETTY_FUNCTION__)) |
| 487 | "Cannot truncate non-integer value!")(static_cast <bool> (getOperand()->getType()->isIntOrPtrTy () && Ty->isIntOrPtrTy() && "Cannot truncate non-integer value!" ) ? void (0) : __assert_fail ("getOperand()->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot truncate non-integer value!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 487, __extension__ __PRETTY_FUNCTION__)); |
| 488 | } |
| 489 | |
| 490 | SCEVZeroExtendExpr::SCEVZeroExtendExpr(const FoldingSetNodeIDRef ID, |
| 491 | const SCEV *op, Type *ty) |
| 492 | : SCEVIntegralCastExpr(ID, scZeroExtend, op, ty) { |
| 493 | assert(getOperand()->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&(static_cast <bool> (getOperand()->getType()->isIntOrPtrTy () && Ty->isIntOrPtrTy() && "Cannot zero extend non-integer value!" ) ? void (0) : __assert_fail ("getOperand()->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot zero extend non-integer value!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 494, __extension__ __PRETTY_FUNCTION__)) |
| 494 | "Cannot zero extend non-integer value!")(static_cast <bool> (getOperand()->getType()->isIntOrPtrTy () && Ty->isIntOrPtrTy() && "Cannot zero extend non-integer value!" ) ? void (0) : __assert_fail ("getOperand()->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot zero extend non-integer value!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 494, __extension__ __PRETTY_FUNCTION__)); |
| 495 | } |
| 496 | |
| 497 | SCEVSignExtendExpr::SCEVSignExtendExpr(const FoldingSetNodeIDRef ID, |
| 498 | const SCEV *op, Type *ty) |
| 499 | : SCEVIntegralCastExpr(ID, scSignExtend, op, ty) { |
| 500 | assert(getOperand()->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&(static_cast <bool> (getOperand()->getType()->isIntOrPtrTy () && Ty->isIntOrPtrTy() && "Cannot sign extend non-integer value!" ) ? void (0) : __assert_fail ("getOperand()->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot sign extend non-integer value!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 501, __extension__ __PRETTY_FUNCTION__)) |
| 501 | "Cannot sign extend non-integer value!")(static_cast <bool> (getOperand()->getType()->isIntOrPtrTy () && Ty->isIntOrPtrTy() && "Cannot sign extend non-integer value!" ) ? void (0) : __assert_fail ("getOperand()->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot sign extend non-integer value!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 501, __extension__ __PRETTY_FUNCTION__)); |
| 502 | } |
| 503 | |
| 504 | void SCEVUnknown::deleted() { |
| 505 | // Clear this SCEVUnknown from various maps. |
| 506 | SE->forgetMemoizedResults(this); |
| 507 | |
| 508 | // Remove this SCEVUnknown from the uniquing map. |
| 509 | SE->UniqueSCEVs.RemoveNode(this); |
| 510 | |
| 511 | // Release the value. |
| 512 | setValPtr(nullptr); |
| 513 | } |
| 514 | |
| 515 | void SCEVUnknown::allUsesReplacedWith(Value *New) { |
| 516 | // Remove this SCEVUnknown from the uniquing map. |
| 517 | SE->UniqueSCEVs.RemoveNode(this); |
| 518 | |
| 519 | // Update this SCEVUnknown to point to the new value. This is needed |
| 520 | // because there may still be outstanding SCEVs which still point to |
| 521 | // this SCEVUnknown. |
| 522 | setValPtr(New); |
| 523 | } |
| 524 | |
| 525 | bool SCEVUnknown::isSizeOf(Type *&AllocTy) const { |
| 526 | if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(getValue())) |
| 527 | if (VCE->getOpcode() == Instruction::PtrToInt) |
| 528 | if (ConstantExpr *CE = dyn_cast<ConstantExpr>(VCE->getOperand(0))) |
| 529 | if (CE->getOpcode() == Instruction::GetElementPtr && |
| 530 | CE->getOperand(0)->isNullValue() && |
| 531 | CE->getNumOperands() == 2) |
| 532 | if (ConstantInt *CI = dyn_cast<ConstantInt>(CE->getOperand(1))) |
| 533 | if (CI->isOne()) { |
| 534 | AllocTy = cast<PointerType>(CE->getOperand(0)->getType()) |
| 535 | ->getElementType(); |
| 536 | return true; |
| 537 | } |
| 538 | |
| 539 | return false; |
| 540 | } |
| 541 | |
| 542 | bool SCEVUnknown::isAlignOf(Type *&AllocTy) const { |
| 543 | if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(getValue())) |
| 544 | if (VCE->getOpcode() == Instruction::PtrToInt) |
| 545 | if (ConstantExpr *CE = dyn_cast<ConstantExpr>(VCE->getOperand(0))) |
| 546 | if (CE->getOpcode() == Instruction::GetElementPtr && |
| 547 | CE->getOperand(0)->isNullValue()) { |
| 548 | Type *Ty = |
| 549 | cast<PointerType>(CE->getOperand(0)->getType())->getElementType(); |
| 550 | if (StructType *STy = dyn_cast<StructType>(Ty)) |
| 551 | if (!STy->isPacked() && |
| 552 | CE->getNumOperands() == 3 && |
| 553 | CE->getOperand(1)->isNullValue()) { |
| 554 | if (ConstantInt *CI = dyn_cast<ConstantInt>(CE->getOperand(2))) |
| 555 | if (CI->isOne() && |
| 556 | STy->getNumElements() == 2 && |
| 557 | STy->getElementType(0)->isIntegerTy(1)) { |
| 558 | AllocTy = STy->getElementType(1); |
| 559 | return true; |
| 560 | } |
| 561 | } |
| 562 | } |
| 563 | |
| 564 | return false; |
| 565 | } |
| 566 | |
| 567 | bool SCEVUnknown::isOffsetOf(Type *&CTy, Constant *&FieldNo) const { |
| 568 | if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(getValue())) |
| 569 | if (VCE->getOpcode() == Instruction::PtrToInt) |
| 570 | if (ConstantExpr *CE = dyn_cast<ConstantExpr>(VCE->getOperand(0))) |
| 571 | if (CE->getOpcode() == Instruction::GetElementPtr && |
| 572 | CE->getNumOperands() == 3 && |
| 573 | CE->getOperand(0)->isNullValue() && |
| 574 | CE->getOperand(1)->isNullValue()) { |
| 575 | Type *Ty = |
| 576 | cast<PointerType>(CE->getOperand(0)->getType())->getElementType(); |
| 577 | // Ignore vector types here so that ScalarEvolutionExpander doesn't |
| 578 | // emit getelementptrs that index into vectors. |
| 579 | if (Ty->isStructTy() || Ty->isArrayTy()) { |
| 580 | CTy = Ty; |
| 581 | FieldNo = CE->getOperand(2); |
| 582 | return true; |
| 583 | } |
| 584 | } |
| 585 | |
| 586 | return false; |
| 587 | } |
| 588 | |
| 589 | //===----------------------------------------------------------------------===// |
| 590 | // SCEV Utilities |
| 591 | //===----------------------------------------------------------------------===// |
| 592 | |
| 593 | /// Compare the two values \p LV and \p RV in terms of their "complexity" where |
| 594 | /// "complexity" is a partial (and somewhat ad-hoc) relation used to order |
| 595 | /// operands in SCEV expressions. \p EqCache is a set of pairs of values that |
| 596 | /// have been previously deemed to be "equally complex" by this routine. It is |
| 597 | /// intended to avoid exponential time complexity in cases like: |
| 598 | /// |
| 599 | /// %a = f(%x, %y) |
| 600 | /// %b = f(%a, %a) |
| 601 | /// %c = f(%b, %b) |
| 602 | /// |
| 603 | /// %d = f(%x, %y) |
| 604 | /// %e = f(%d, %d) |
| 605 | /// %f = f(%e, %e) |
| 606 | /// |
| 607 | /// CompareValueComplexity(%f, %c) |
| 608 | /// |
| 609 | /// Since we do not continue running this routine on expression trees once we |
| 610 | /// have seen unequal values, there is no need to track them in the cache. |
| 611 | static int |
| 612 | CompareValueComplexity(EquivalenceClasses<const Value *> &EqCacheValue, |
| 613 | const LoopInfo *const LI, Value *LV, Value *RV, |
| 614 | unsigned Depth) { |
| 615 | if (Depth > MaxValueCompareDepth || EqCacheValue.isEquivalent(LV, RV)) |
| 616 | return 0; |
| 617 | |
| 618 | // Order pointer values after integer values. This helps SCEVExpander form |
| 619 | // GEPs. |
| 620 | bool LIsPointer = LV->getType()->isPointerTy(), |
| 621 | RIsPointer = RV->getType()->isPointerTy(); |
| 622 | if (LIsPointer != RIsPointer) |
| 623 | return (int)LIsPointer - (int)RIsPointer; |
| 624 | |
| 625 | // Compare getValueID values. |
| 626 | unsigned LID = LV->getValueID(), RID = RV->getValueID(); |
| 627 | if (LID != RID) |
| 628 | return (int)LID - (int)RID; |
| 629 | |
| 630 | // Sort arguments by their position. |
| 631 | if (const auto *LA = dyn_cast<Argument>(LV)) { |
| 632 | const auto *RA = cast<Argument>(RV); |
| 633 | unsigned LArgNo = LA->getArgNo(), RArgNo = RA->getArgNo(); |
| 634 | return (int)LArgNo - (int)RArgNo; |
| 635 | } |
| 636 | |
| 637 | if (const auto *LGV = dyn_cast<GlobalValue>(LV)) { |
| 638 | const auto *RGV = cast<GlobalValue>(RV); |
| 639 | |
| 640 | const auto IsGVNameSemantic = [&](const GlobalValue *GV) { |
| 641 | auto LT = GV->getLinkage(); |
| 642 | return !(GlobalValue::isPrivateLinkage(LT) || |
| 643 | GlobalValue::isInternalLinkage(LT)); |
| 644 | }; |
| 645 | |
| 646 | // Use the names to distinguish the two values, but only if the |
| 647 | // names are semantically important. |
| 648 | if (IsGVNameSemantic(LGV) && IsGVNameSemantic(RGV)) |
| 649 | return LGV->getName().compare(RGV->getName()); |
| 650 | } |
| 651 | |
| 652 | // For instructions, compare their loop depth, and their operand count. This |
| 653 | // is pretty loose. |
| 654 | if (const auto *LInst = dyn_cast<Instruction>(LV)) { |
| 655 | const auto *RInst = cast<Instruction>(RV); |
| 656 | |
| 657 | // Compare loop depths. |
| 658 | const BasicBlock *LParent = LInst->getParent(), |
| 659 | *RParent = RInst->getParent(); |
| 660 | if (LParent != RParent) { |
| 661 | unsigned LDepth = LI->getLoopDepth(LParent), |
| 662 | RDepth = LI->getLoopDepth(RParent); |
| 663 | if (LDepth != RDepth) |
| 664 | return (int)LDepth - (int)RDepth; |
| 665 | } |
| 666 | |
| 667 | // Compare the number of operands. |
| 668 | unsigned LNumOps = LInst->getNumOperands(), |
| 669 | RNumOps = RInst->getNumOperands(); |
| 670 | if (LNumOps != RNumOps) |
| 671 | return (int)LNumOps - (int)RNumOps; |
| 672 | |
| 673 | for (unsigned Idx : seq(0u, LNumOps)) { |
| 674 | int Result = |
| 675 | CompareValueComplexity(EqCacheValue, LI, LInst->getOperand(Idx), |
| 676 | RInst->getOperand(Idx), Depth + 1); |
| 677 | if (Result != 0) |
| 678 | return Result; |
| 679 | } |
| 680 | } |
| 681 | |
| 682 | EqCacheValue.unionSets(LV, RV); |
| 683 | return 0; |
| 684 | } |
| 685 | |
| 686 | // Return negative, zero, or positive, if LHS is less than, equal to, or greater |
| 687 | // than RHS, respectively. A three-way result allows recursive comparisons to be |
| 688 | // more efficient. |
| 689 | // If the max analysis depth was reached, return None, assuming we do not know |
| 690 | // if they are equivalent for sure. |
| 691 | static Optional<int> |
| 692 | CompareSCEVComplexity(EquivalenceClasses<const SCEV *> &EqCacheSCEV, |
| 693 | EquivalenceClasses<const Value *> &EqCacheValue, |
| 694 | const LoopInfo *const LI, const SCEV *LHS, |
| 695 | const SCEV *RHS, DominatorTree &DT, unsigned Depth = 0) { |
| 696 | // Fast-path: SCEVs are uniqued so we can do a quick equality check. |
| 697 | if (LHS == RHS) |
| 698 | return 0; |
| 699 | |
| 700 | // Primarily, sort the SCEVs by their getSCEVType(). |
| 701 | SCEVTypes LType = LHS->getSCEVType(), RType = RHS->getSCEVType(); |
| 702 | if (LType != RType) |
| 703 | return (int)LType - (int)RType; |
| 704 | |
| 705 | if (EqCacheSCEV.isEquivalent(LHS, RHS)) |
| 706 | return 0; |
| 707 | |
| 708 | if (Depth > MaxSCEVCompareDepth) |
| 709 | return None; |
| 710 | |
| 711 | // Aside from the getSCEVType() ordering, the particular ordering |
| 712 | // isn't very important except that it's beneficial to be consistent, |
| 713 | // so that (a + b) and (b + a) don't end up as different expressions. |
| 714 | switch (LType) { |
| 715 | case scUnknown: { |
| 716 | const SCEVUnknown *LU = cast<SCEVUnknown>(LHS); |
| 717 | const SCEVUnknown *RU = cast<SCEVUnknown>(RHS); |
| 718 | |
| 719 | int X = CompareValueComplexity(EqCacheValue, LI, LU->getValue(), |
| 720 | RU->getValue(), Depth + 1); |
| 721 | if (X == 0) |
| 722 | EqCacheSCEV.unionSets(LHS, RHS); |
| 723 | return X; |
| 724 | } |
| 725 | |
| 726 | case scConstant: { |
| 727 | const SCEVConstant *LC = cast<SCEVConstant>(LHS); |
| 728 | const SCEVConstant *RC = cast<SCEVConstant>(RHS); |
| 729 | |
| 730 | // Compare constant values. |
| 731 | const APInt &LA = LC->getAPInt(); |
| 732 | const APInt &RA = RC->getAPInt(); |
| 733 | unsigned LBitWidth = LA.getBitWidth(), RBitWidth = RA.getBitWidth(); |
| 734 | if (LBitWidth != RBitWidth) |
| 735 | return (int)LBitWidth - (int)RBitWidth; |
| 736 | return LA.ult(RA) ? -1 : 1; |
| 737 | } |
| 738 | |
| 739 | case scAddRecExpr: { |
| 740 | const SCEVAddRecExpr *LA = cast<SCEVAddRecExpr>(LHS); |
| 741 | const SCEVAddRecExpr *RA = cast<SCEVAddRecExpr>(RHS); |
| 742 | |
| 743 | // There is always a dominance between two recs that are used by one SCEV, |
| 744 | // so we can safely sort recs by loop header dominance. We require such |
| 745 | // order in getAddExpr. |
| 746 | const Loop *LLoop = LA->getLoop(), *RLoop = RA->getLoop(); |
| 747 | if (LLoop != RLoop) { |
| 748 | const BasicBlock *LHead = LLoop->getHeader(), *RHead = RLoop->getHeader(); |
| 749 | assert(LHead != RHead && "Two loops share the same header?")(static_cast <bool> (LHead != RHead && "Two loops share the same header?" ) ? void (0) : __assert_fail ("LHead != RHead && \"Two loops share the same header?\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 749, __extension__ __PRETTY_FUNCTION__)); |
| 750 | if (DT.dominates(LHead, RHead)) |
| 751 | return 1; |
| 752 | else |
| 753 | assert(DT.dominates(RHead, LHead) &&(static_cast <bool> (DT.dominates(RHead, LHead) && "No dominance between recurrences used by one SCEV?") ? void (0) : __assert_fail ("DT.dominates(RHead, LHead) && \"No dominance between recurrences used by one SCEV?\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 754, __extension__ __PRETTY_FUNCTION__)) |
| 754 | "No dominance between recurrences used by one SCEV?")(static_cast <bool> (DT.dominates(RHead, LHead) && "No dominance between recurrences used by one SCEV?") ? void (0) : __assert_fail ("DT.dominates(RHead, LHead) && \"No dominance between recurrences used by one SCEV?\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 754, __extension__ __PRETTY_FUNCTION__)); |
| 755 | return -1; |
| 756 | } |
| 757 | |
| 758 | // Addrec complexity grows with operand count. |
| 759 | unsigned LNumOps = LA->getNumOperands(), RNumOps = RA->getNumOperands(); |
| 760 | if (LNumOps != RNumOps) |
| 761 | return (int)LNumOps - (int)RNumOps; |
| 762 | |
| 763 | // Lexicographically compare. |
| 764 | for (unsigned i = 0; i != LNumOps; ++i) { |
| 765 | auto X = CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI, |
| 766 | LA->getOperand(i), RA->getOperand(i), DT, |
| 767 | Depth + 1); |
| 768 | if (X != 0) |
| 769 | return X; |
| 770 | } |
| 771 | EqCacheSCEV.unionSets(LHS, RHS); |
| 772 | return 0; |
| 773 | } |
| 774 | |
| 775 | case scAddExpr: |
| 776 | case scMulExpr: |
| 777 | case scSMaxExpr: |
| 778 | case scUMaxExpr: |
| 779 | case scSMinExpr: |
| 780 | case scUMinExpr: { |
| 781 | const SCEVNAryExpr *LC = cast<SCEVNAryExpr>(LHS); |
| 782 | const SCEVNAryExpr *RC = cast<SCEVNAryExpr>(RHS); |
| 783 | |
| 784 | // Lexicographically compare n-ary expressions. |
| 785 | unsigned LNumOps = LC->getNumOperands(), RNumOps = RC->getNumOperands(); |
| 786 | if (LNumOps != RNumOps) |
| 787 | return (int)LNumOps - (int)RNumOps; |
| 788 | |
| 789 | for (unsigned i = 0; i != LNumOps; ++i) { |
| 790 | auto X = CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI, |
| 791 | LC->getOperand(i), RC->getOperand(i), DT, |
| 792 | Depth + 1); |
| 793 | if (X != 0) |
| 794 | return X; |
| 795 | } |
| 796 | EqCacheSCEV.unionSets(LHS, RHS); |
| 797 | return 0; |
| 798 | } |
| 799 | |
| 800 | case scUDivExpr: { |
| 801 | const SCEVUDivExpr *LC = cast<SCEVUDivExpr>(LHS); |
| 802 | const SCEVUDivExpr *RC = cast<SCEVUDivExpr>(RHS); |
| 803 | |
| 804 | // Lexicographically compare udiv expressions. |
| 805 | auto X = CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI, LC->getLHS(), |
| 806 | RC->getLHS(), DT, Depth + 1); |
| 807 | if (X != 0) |
| 808 | return X; |
| 809 | X = CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI, LC->getRHS(), |
| 810 | RC->getRHS(), DT, Depth + 1); |
| 811 | if (X == 0) |
| 812 | EqCacheSCEV.unionSets(LHS, RHS); |
| 813 | return X; |
| 814 | } |
| 815 | |
| 816 | case scPtrToInt: |
| 817 | case scTruncate: |
| 818 | case scZeroExtend: |
| 819 | case scSignExtend: { |
| 820 | const SCEVCastExpr *LC = cast<SCEVCastExpr>(LHS); |
| 821 | const SCEVCastExpr *RC = cast<SCEVCastExpr>(RHS); |
| 822 | |
| 823 | // Compare cast expressions by operand. |
| 824 | auto X = |
| 825 | CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI, LC->getOperand(), |
| 826 | RC->getOperand(), DT, Depth + 1); |
| 827 | if (X == 0) |
| 828 | EqCacheSCEV.unionSets(LHS, RHS); |
| 829 | return X; |
| 830 | } |
| 831 | |
| 832 | case scCouldNotCompute: |
| 833 | llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!")::llvm::llvm_unreachable_internal("Attempt to use a SCEVCouldNotCompute object!" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 833); |
| 834 | } |
| 835 | llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 835); |
| 836 | } |
| 837 | |
| 838 | /// Given a list of SCEV objects, order them by their complexity, and group |
| 839 | /// objects of the same complexity together by value. When this routine is |
| 840 | /// finished, we know that any duplicates in the vector are consecutive and that |
| 841 | /// complexity is monotonically increasing. |
| 842 | /// |
| 843 | /// Note that we go take special precautions to ensure that we get deterministic |
| 844 | /// results from this routine. In other words, we don't want the results of |
| 845 | /// this to depend on where the addresses of various SCEV objects happened to |
| 846 | /// land in memory. |
| 847 | static void GroupByComplexity(SmallVectorImpl<const SCEV *> &Ops, |
| 848 | LoopInfo *LI, DominatorTree &DT) { |
| 849 | if (Ops.size() < 2) return; // Noop |
| 850 | |
| 851 | EquivalenceClasses<const SCEV *> EqCacheSCEV; |
| 852 | EquivalenceClasses<const Value *> EqCacheValue; |
| 853 | |
| 854 | // Whether LHS has provably less complexity than RHS. |
| 855 | auto IsLessComplex = [&](const SCEV *LHS, const SCEV *RHS) { |
| 856 | auto Complexity = |
| 857 | CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI, LHS, RHS, DT); |
| 858 | return Complexity && *Complexity < 0; |
| 859 | }; |
| 860 | if (Ops.size() == 2) { |
| 861 | // This is the common case, which also happens to be trivially simple. |
| 862 | // Special case it. |
| 863 | const SCEV *&LHS = Ops[0], *&RHS = Ops[1]; |
| 864 | if (IsLessComplex(RHS, LHS)) |
| 865 | std::swap(LHS, RHS); |
| 866 | return; |
| 867 | } |
| 868 | |
| 869 | // Do the rough sort by complexity. |
| 870 | llvm::stable_sort(Ops, [&](const SCEV *LHS, const SCEV *RHS) { |
| 871 | return IsLessComplex(LHS, RHS); |
| 872 | }); |
| 873 | |
| 874 | // Now that we are sorted by complexity, group elements of the same |
| 875 | // complexity. Note that this is, at worst, N^2, but the vector is likely to |
| 876 | // be extremely short in practice. Note that we take this approach because we |
| 877 | // do not want to depend on the addresses of the objects we are grouping. |
| 878 | for (unsigned i = 0, e = Ops.size(); i != e-2; ++i) { |
| 879 | const SCEV *S = Ops[i]; |
| 880 | unsigned Complexity = S->getSCEVType(); |
| 881 | |
| 882 | // If there are any objects of the same complexity and same value as this |
| 883 | // one, group them. |
| 884 | for (unsigned j = i+1; j != e && Ops[j]->getSCEVType() == Complexity; ++j) { |
| 885 | if (Ops[j] == S) { // Found a duplicate. |
| 886 | // Move it to immediately after i'th element. |
| 887 | std::swap(Ops[i+1], Ops[j]); |
| 888 | ++i; // no need to rescan it. |
| 889 | if (i == e-2) return; // Done! |
| 890 | } |
| 891 | } |
| 892 | } |
| 893 | } |
| 894 | |
| 895 | /// Returns true if \p Ops contains a huge SCEV (the subtree of S contains at |
| 896 | /// least HugeExprThreshold nodes). |
| 897 | static bool hasHugeExpression(ArrayRef<const SCEV *> Ops) { |
| 898 | return any_of(Ops, [](const SCEV *S) { |
| 899 | return S->getExpressionSize() >= HugeExprThreshold; |
| 900 | }); |
| 901 | } |
| 902 | |
| 903 | //===----------------------------------------------------------------------===// |
| 904 | // Simple SCEV method implementations |
| 905 | //===----------------------------------------------------------------------===// |
| 906 | |
| 907 | /// Compute BC(It, K). The result has width W. Assume, K > 0. |
| 908 | static const SCEV *BinomialCoefficient(const SCEV *It, unsigned K, |
| 909 | ScalarEvolution &SE, |
| 910 | Type *ResultTy) { |
| 911 | // Handle the simplest case efficiently. |
| 912 | if (K == 1) |
| 913 | return SE.getTruncateOrZeroExtend(It, ResultTy); |
| 914 | |
| 915 | // We are using the following formula for BC(It, K): |
| 916 | // |
| 917 | // BC(It, K) = (It * (It - 1) * ... * (It - K + 1)) / K! |
| 918 | // |
| 919 | // Suppose, W is the bitwidth of the return value. We must be prepared for |
| 920 | // overflow. Hence, we must assure that the result of our computation is |
| 921 | // equal to the accurate one modulo 2^W. Unfortunately, division isn't |
| 922 | // safe in modular arithmetic. |
| 923 | // |
| 924 | // However, this code doesn't use exactly that formula; the formula it uses |
| 925 | // is something like the following, where T is the number of factors of 2 in |
| 926 | // K! (i.e. trailing zeros in the binary representation of K!), and ^ is |
| 927 | // exponentiation: |
| 928 | // |
| 929 | // BC(It, K) = (It * (It - 1) * ... * (It - K + 1)) / 2^T / (K! / 2^T) |
| 930 | // |
| 931 | // This formula is trivially equivalent to the previous formula. However, |
| 932 | // this formula can be implemented much more efficiently. The trick is that |
| 933 | // K! / 2^T is odd, and exact division by an odd number *is* safe in modular |
| 934 | // arithmetic. To do exact division in modular arithmetic, all we have |
| 935 | // to do is multiply by the inverse. Therefore, this step can be done at |
| 936 | // width W. |
| 937 | // |
| 938 | // The next issue is how to safely do the division by 2^T. The way this |
| 939 | // is done is by doing the multiplication step at a width of at least W + T |
| 940 | // bits. This way, the bottom W+T bits of the product are accurate. Then, |
| 941 | // when we perform the division by 2^T (which is equivalent to a right shift |
| 942 | // by T), the bottom W bits are accurate. Extra bits are okay; they'll get |
| 943 | // truncated out after the division by 2^T. |
| 944 | // |
| 945 | // In comparison to just directly using the first formula, this technique |
| 946 | // is much more efficient; using the first formula requires W * K bits, |
| 947 | // but this formula less than W + K bits. Also, the first formula requires |
| 948 | // a division step, whereas this formula only requires multiplies and shifts. |
| 949 | // |
| 950 | // It doesn't matter whether the subtraction step is done in the calculation |
| 951 | // width or the input iteration count's width; if the subtraction overflows, |
| 952 | // the result must be zero anyway. We prefer here to do it in the width of |
| 953 | // the induction variable because it helps a lot for certain cases; CodeGen |
| 954 | // isn't smart enough to ignore the overflow, which leads to much less |
| 955 | // efficient code if the width of the subtraction is wider than the native |
| 956 | // register width. |
| 957 | // |
| 958 | // (It's possible to not widen at all by pulling out factors of 2 before |
| 959 | // the multiplication; for example, K=2 can be calculated as |
| 960 | // It/2*(It+(It*INT_MIN/INT_MIN)+-1). However, it requires |
| 961 | // extra arithmetic, so it's not an obvious win, and it gets |
| 962 | // much more complicated for K > 3.) |
| 963 | |
| 964 | // Protection from insane SCEVs; this bound is conservative, |
| 965 | // but it probably doesn't matter. |
| 966 | if (K > 1000) |
| 967 | return SE.getCouldNotCompute(); |
| 968 | |
| 969 | unsigned W = SE.getTypeSizeInBits(ResultTy); |
| 970 | |
| 971 | // Calculate K! / 2^T and T; we divide out the factors of two before |
| 972 | // multiplying for calculating K! / 2^T to avoid overflow. |
| 973 | // Other overflow doesn't matter because we only care about the bottom |
| 974 | // W bits of the result. |
| 975 | APInt OddFactorial(W, 1); |
| 976 | unsigned T = 1; |
| 977 | for (unsigned i = 3; i <= K; ++i) { |
| 978 | APInt Mult(W, i); |
| 979 | unsigned TwoFactors = Mult.countTrailingZeros(); |
| 980 | T += TwoFactors; |
| 981 | Mult.lshrInPlace(TwoFactors); |
| 982 | OddFactorial *= Mult; |
| 983 | } |
| 984 | |
| 985 | // We need at least W + T bits for the multiplication step |
| 986 | unsigned CalculationBits = W + T; |
| 987 | |
| 988 | // Calculate 2^T, at width T+W. |
| 989 | APInt DivFactor = APInt::getOneBitSet(CalculationBits, T); |
| 990 | |
| 991 | // Calculate the multiplicative inverse of K! / 2^T; |
| 992 | // this multiplication factor will perform the exact division by |
| 993 | // K! / 2^T. |
| 994 | APInt Mod = APInt::getSignedMinValue(W+1); |
| 995 | APInt MultiplyFactor = OddFactorial.zext(W+1); |
| 996 | MultiplyFactor = MultiplyFactor.multiplicativeInverse(Mod); |
| 997 | MultiplyFactor = MultiplyFactor.trunc(W); |
| 998 | |
| 999 | // Calculate the product, at width T+W |
| 1000 | IntegerType *CalculationTy = IntegerType::get(SE.getContext(), |
| 1001 | CalculationBits); |
| 1002 | const SCEV *Dividend = SE.getTruncateOrZeroExtend(It, CalculationTy); |
| 1003 | for (unsigned i = 1; i != K; ++i) { |
| 1004 | const SCEV *S = SE.getMinusSCEV(It, SE.getConstant(It->getType(), i)); |
| 1005 | Dividend = SE.getMulExpr(Dividend, |
| 1006 | SE.getTruncateOrZeroExtend(S, CalculationTy)); |
| 1007 | } |
| 1008 | |
| 1009 | // Divide by 2^T |
| 1010 | const SCEV *DivResult = SE.getUDivExpr(Dividend, SE.getConstant(DivFactor)); |
| 1011 | |
| 1012 | // Truncate the result, and divide by K! / 2^T. |
| 1013 | |
| 1014 | return SE.getMulExpr(SE.getConstant(MultiplyFactor), |
| 1015 | SE.getTruncateOrZeroExtend(DivResult, ResultTy)); |
| 1016 | } |
| 1017 | |
| 1018 | /// Return the value of this chain of recurrences at the specified iteration |
| 1019 | /// number. We can evaluate this recurrence by multiplying each element in the |
| 1020 | /// chain by the binomial coefficient corresponding to it. In other words, we |
| 1021 | /// can evaluate {A,+,B,+,C,+,D} as: |
| 1022 | /// |
| 1023 | /// A*BC(It, 0) + B*BC(It, 1) + C*BC(It, 2) + D*BC(It, 3) |
| 1024 | /// |
| 1025 | /// where BC(It, k) stands for binomial coefficient. |
| 1026 | const SCEV *SCEVAddRecExpr::evaluateAtIteration(const SCEV *It, |
| 1027 | ScalarEvolution &SE) const { |
| 1028 | const SCEV *Result = getStart(); |
| 1029 | for (unsigned i = 1, e = getNumOperands(); i != e; ++i) { |
| 1030 | // The computation is correct in the face of overflow provided that the |
| 1031 | // multiplication is performed _after_ the evaluation of the binomial |
| 1032 | // coefficient. |
| 1033 | const SCEV *Coeff = BinomialCoefficient(It, i, SE, getType()); |
| 1034 | if (isa<SCEVCouldNotCompute>(Coeff)) |
| 1035 | return Coeff; |
| 1036 | |
| 1037 | Result = SE.getAddExpr(Result, SE.getMulExpr(getOperand(i), Coeff)); |
| 1038 | } |
| 1039 | return Result; |
| 1040 | } |
| 1041 | |
| 1042 | //===----------------------------------------------------------------------===// |
| 1043 | // SCEV Expression folder implementations |
| 1044 | //===----------------------------------------------------------------------===// |
| 1045 | |
| 1046 | const SCEV *ScalarEvolution::getLosslessPtrToIntExpr(const SCEV *Op, |
| 1047 | unsigned Depth) { |
| 1048 | assert(Depth <= 1 &&(static_cast <bool> (Depth <= 1 && "getLosslessPtrToIntExpr() should self-recurse at most once." ) ? void (0) : __assert_fail ("Depth <= 1 && \"getLosslessPtrToIntExpr() should self-recurse at most once.\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 1049, __extension__ __PRETTY_FUNCTION__)) |
| 1049 | "getLosslessPtrToIntExpr() should self-recurse at most once.")(static_cast <bool> (Depth <= 1 && "getLosslessPtrToIntExpr() should self-recurse at most once." ) ? void (0) : __assert_fail ("Depth <= 1 && \"getLosslessPtrToIntExpr() should self-recurse at most once.\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 1049, __extension__ __PRETTY_FUNCTION__)); |
| 1050 | |
| 1051 | // We could be called with an integer-typed operands during SCEV rewrites. |
| 1052 | // Since the operand is an integer already, just perform zext/trunc/self cast. |
| 1053 | if (!Op->getType()->isPointerTy()) |
| 1054 | return Op; |
| 1055 | |
| 1056 | assert(!getDataLayout().isNonIntegralPointerType(Op->getType()) &&(static_cast <bool> (!getDataLayout().isNonIntegralPointerType (Op->getType()) && "Source pointer type must be integral for ptrtoint!" ) ? void (0) : __assert_fail ("!getDataLayout().isNonIntegralPointerType(Op->getType()) && \"Source pointer type must be integral for ptrtoint!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 1057, __extension__ __PRETTY_FUNCTION__)) |
| 1057 | "Source pointer type must be integral for ptrtoint!")(static_cast <bool> (!getDataLayout().isNonIntegralPointerType (Op->getType()) && "Source pointer type must be integral for ptrtoint!" ) ? void (0) : __assert_fail ("!getDataLayout().isNonIntegralPointerType(Op->getType()) && \"Source pointer type must be integral for ptrtoint!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 1057, __extension__ __PRETTY_FUNCTION__)); |
| 1058 | |
| 1059 | // What would be an ID for such a SCEV cast expression? |
| 1060 | FoldingSetNodeID ID; |
| 1061 | ID.AddInteger(scPtrToInt); |
| 1062 | ID.AddPointer(Op); |
| 1063 | |
| 1064 | void *IP = nullptr; |
| 1065 | |
| 1066 | // Is there already an expression for such a cast? |
| 1067 | if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) |
| 1068 | return S; |
| 1069 | |
| 1070 | Type *IntPtrTy = getDataLayout().getIntPtrType(Op->getType()); |
| 1071 | |
| 1072 | // We can only model ptrtoint if SCEV's effective (integer) type |
| 1073 | // is sufficiently wide to represent all possible pointer values. |
| 1074 | if (getDataLayout().getTypeSizeInBits(getEffectiveSCEVType(Op->getType())) != |
| 1075 | getDataLayout().getTypeSizeInBits(IntPtrTy)) |
| 1076 | return getCouldNotCompute(); |
| 1077 | |
| 1078 | // If not, is this expression something we can't reduce any further? |
| 1079 | if (auto *U = dyn_cast<SCEVUnknown>(Op)) { |
| 1080 | // Perform some basic constant folding. If the operand of the ptr2int cast |
| 1081 | // is a null pointer, don't create a ptr2int SCEV expression (that will be |
| 1082 | // left as-is), but produce a zero constant. |
| 1083 | // NOTE: We could handle a more general case, but lack motivational cases. |
| 1084 | if (isa<ConstantPointerNull>(U->getValue())) |
| 1085 | return getZero(IntPtrTy); |
| 1086 | |
| 1087 | // Create an explicit cast node. |
| 1088 | // We can reuse the existing insert position since if we get here, |
| 1089 | // we won't have made any changes which would invalidate it. |
| 1090 | SCEV *S = new (SCEVAllocator) |
| 1091 | SCEVPtrToIntExpr(ID.Intern(SCEVAllocator), Op, IntPtrTy); |
| 1092 | UniqueSCEVs.InsertNode(S, IP); |
| 1093 | addToLoopUseLists(S); |
| 1094 | return S; |
| 1095 | } |
| 1096 | |
| 1097 | assert(Depth == 0 && "getLosslessPtrToIntExpr() should not self-recurse for "(static_cast <bool> (Depth == 0 && "getLosslessPtrToIntExpr() should not self-recurse for " "non-SCEVUnknown's.") ? void (0) : __assert_fail ("Depth == 0 && \"getLosslessPtrToIntExpr() should not self-recurse for \" \"non-SCEVUnknown's.\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 1098, __extension__ __PRETTY_FUNCTION__)) |
| 1098 | "non-SCEVUnknown's.")(static_cast <bool> (Depth == 0 && "getLosslessPtrToIntExpr() should not self-recurse for " "non-SCEVUnknown's.") ? void (0) : __assert_fail ("Depth == 0 && \"getLosslessPtrToIntExpr() should not self-recurse for \" \"non-SCEVUnknown's.\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 1098, __extension__ __PRETTY_FUNCTION__)); |
| 1099 | |
| 1100 | // Otherwise, we've got some expression that is more complex than just a |
| 1101 | // single SCEVUnknown. But we don't want to have a SCEVPtrToIntExpr of an |
| 1102 | // arbitrary expression, we want to have SCEVPtrToIntExpr of an SCEVUnknown |
| 1103 | // only, and the expressions must otherwise be integer-typed. |
| 1104 | // So sink the cast down to the SCEVUnknown's. |
| 1105 | |
| 1106 | /// The SCEVPtrToIntSinkingRewriter takes a scalar evolution expression, |
| 1107 | /// which computes a pointer-typed value, and rewrites the whole expression |
| 1108 | /// tree so that *all* the computations are done on integers, and the only |
| 1109 | /// pointer-typed operands in the expression are SCEVUnknown. |
| 1110 | class SCEVPtrToIntSinkingRewriter |
| 1111 | : public SCEVRewriteVisitor<SCEVPtrToIntSinkingRewriter> { |
| 1112 | using Base = SCEVRewriteVisitor<SCEVPtrToIntSinkingRewriter>; |
| 1113 | |
| 1114 | public: |
| 1115 | SCEVPtrToIntSinkingRewriter(ScalarEvolution &SE) : SCEVRewriteVisitor(SE) {} |
| 1116 | |
| 1117 | static const SCEV *rewrite(const SCEV *Scev, ScalarEvolution &SE) { |
| 1118 | SCEVPtrToIntSinkingRewriter Rewriter(SE); |
| 1119 | return Rewriter.visit(Scev); |
| 1120 | } |
| 1121 | |
| 1122 | const SCEV *visit(const SCEV *S) { |
| 1123 | Type *STy = S->getType(); |
| 1124 | // If the expression is not pointer-typed, just keep it as-is. |
| 1125 | if (!STy->isPointerTy()) |
| 1126 | return S; |
| 1127 | // Else, recursively sink the cast down into it. |
| 1128 | return Base::visit(S); |
| 1129 | } |
| 1130 | |
| 1131 | const SCEV *visitAddExpr(const SCEVAddExpr *Expr) { |
| 1132 | SmallVector<const SCEV *, 2> Operands; |
| 1133 | bool Changed = false; |
| 1134 | for (auto *Op : Expr->operands()) { |
| 1135 | Operands.push_back(visit(Op)); |
| 1136 | Changed |= Op != Operands.back(); |
| 1137 | } |
| 1138 | return !Changed ? Expr : SE.getAddExpr(Operands, Expr->getNoWrapFlags()); |
| 1139 | } |
| 1140 | |
| 1141 | const SCEV *visitMulExpr(const SCEVMulExpr *Expr) { |
| 1142 | SmallVector<const SCEV *, 2> Operands; |
| 1143 | bool Changed = false; |
| 1144 | for (auto *Op : Expr->operands()) { |
| 1145 | Operands.push_back(visit(Op)); |
| 1146 | Changed |= Op != Operands.back(); |
| 1147 | } |
| 1148 | return !Changed ? Expr : SE.getMulExpr(Operands, Expr->getNoWrapFlags()); |
| 1149 | } |
| 1150 | |
| 1151 | const SCEV *visitUnknown(const SCEVUnknown *Expr) { |
| 1152 | assert(Expr->getType()->isPointerTy() &&(static_cast <bool> (Expr->getType()->isPointerTy () && "Should only reach pointer-typed SCEVUnknown's." ) ? void (0) : __assert_fail ("Expr->getType()->isPointerTy() && \"Should only reach pointer-typed SCEVUnknown's.\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 1153, __extension__ __PRETTY_FUNCTION__)) |
| 1153 | "Should only reach pointer-typed SCEVUnknown's.")(static_cast <bool> (Expr->getType()->isPointerTy () && "Should only reach pointer-typed SCEVUnknown's." ) ? void (0) : __assert_fail ("Expr->getType()->isPointerTy() && \"Should only reach pointer-typed SCEVUnknown's.\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 1153, __extension__ __PRETTY_FUNCTION__)); |
| 1154 | return SE.getLosslessPtrToIntExpr(Expr, /*Depth=*/1); |
| 1155 | } |
| 1156 | }; |
| 1157 | |
| 1158 | // And actually perform the cast sinking. |
| 1159 | const SCEV *IntOp = SCEVPtrToIntSinkingRewriter::rewrite(Op, *this); |
| 1160 | assert(IntOp->getType()->isIntegerTy() &&(static_cast <bool> (IntOp->getType()->isIntegerTy () && "We must have succeeded in sinking the cast, " "and ending up with an integer-typed expression!" ) ? void (0) : __assert_fail ("IntOp->getType()->isIntegerTy() && \"We must have succeeded in sinking the cast, \" \"and ending up with an integer-typed expression!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 1162, __extension__ __PRETTY_FUNCTION__)) |
| 1161 | "We must have succeeded in sinking the cast, "(static_cast <bool> (IntOp->getType()->isIntegerTy () && "We must have succeeded in sinking the cast, " "and ending up with an integer-typed expression!" ) ? void (0) : __assert_fail ("IntOp->getType()->isIntegerTy() && \"We must have succeeded in sinking the cast, \" \"and ending up with an integer-typed expression!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 1162, __extension__ __PRETTY_FUNCTION__)) |
| 1162 | "and ending up with an integer-typed expression!")(static_cast <bool> (IntOp->getType()->isIntegerTy () && "We must have succeeded in sinking the cast, " "and ending up with an integer-typed expression!" ) ? void (0) : __assert_fail ("IntOp->getType()->isIntegerTy() && \"We must have succeeded in sinking the cast, \" \"and ending up with an integer-typed expression!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 1162, __extension__ __PRETTY_FUNCTION__)); |
| 1163 | return IntOp; |
| 1164 | } |
| 1165 | |
| 1166 | const SCEV *ScalarEvolution::getPtrToIntExpr(const SCEV *Op, Type *Ty) { |
| 1167 | assert(Ty->isIntegerTy() && "Target type must be an integer type!")(static_cast <bool> (Ty->isIntegerTy() && "Target type must be an integer type!" ) ? void (0) : __assert_fail ("Ty->isIntegerTy() && \"Target type must be an integer type!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 1167, __extension__ __PRETTY_FUNCTION__)); |
| 1168 | |
| 1169 | const SCEV *IntOp = getLosslessPtrToIntExpr(Op); |
| 1170 | if (isa<SCEVCouldNotCompute>(IntOp)) |
| 1171 | return IntOp; |
| 1172 | |
| 1173 | return getTruncateOrZeroExtend(IntOp, Ty); |
| 1174 | } |
| 1175 | |
| 1176 | const SCEV *ScalarEvolution::getTruncateExpr(const SCEV *Op, Type *Ty, |
| 1177 | unsigned Depth) { |
| 1178 | assert(getTypeSizeInBits(Op->getType()) > getTypeSizeInBits(Ty) &&(static_cast <bool> (getTypeSizeInBits(Op->getType() ) > getTypeSizeInBits(Ty) && "This is not a truncating conversion!" ) ? void (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) > getTypeSizeInBits(Ty) && \"This is not a truncating conversion!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 1179, __extension__ __PRETTY_FUNCTION__)) |
| 1179 | "This is not a truncating conversion!")(static_cast <bool> (getTypeSizeInBits(Op->getType() ) > getTypeSizeInBits(Ty) && "This is not a truncating conversion!" ) ? void (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) > getTypeSizeInBits(Ty) && \"This is not a truncating conversion!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 1179, __extension__ __PRETTY_FUNCTION__)); |
| 1180 | assert(isSCEVable(Ty) &&(static_cast <bool> (isSCEVable(Ty) && "This is not a conversion to a SCEVable type!" ) ? void (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 1181, __extension__ __PRETTY_FUNCTION__)) |
| 1181 | "This is not a conversion to a SCEVable type!")(static_cast <bool> (isSCEVable(Ty) && "This is not a conversion to a SCEVable type!" ) ? void (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 1181, __extension__ __PRETTY_FUNCTION__)); |
| 1182 | Ty = getEffectiveSCEVType(Ty); |
| 1183 | |
| 1184 | FoldingSetNodeID ID; |
| 1185 | ID.AddInteger(scTruncate); |
| 1186 | ID.AddPointer(Op); |
| 1187 | ID.AddPointer(Ty); |
| 1188 | void *IP = nullptr; |
| 1189 | if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S; |
| 1190 | |
| 1191 | // Fold if the operand is constant. |
| 1192 | if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op)) |
| 1193 | return getConstant( |
| 1194 | cast<ConstantInt>(ConstantExpr::getTrunc(SC->getValue(), Ty))); |
| 1195 | |
| 1196 | // trunc(trunc(x)) --> trunc(x) |
| 1197 | if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op)) |
| 1198 | return getTruncateExpr(ST->getOperand(), Ty, Depth + 1); |
| 1199 | |
| 1200 | // trunc(sext(x)) --> sext(x) if widening or trunc(x) if narrowing |
| 1201 | if (const SCEVSignExtendExpr *SS = dyn_cast<SCEVSignExtendExpr>(Op)) |
| 1202 | return getTruncateOrSignExtend(SS->getOperand(), Ty, Depth + 1); |
| 1203 | |
| 1204 | // trunc(zext(x)) --> zext(x) if widening or trunc(x) if narrowing |
| 1205 | if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op)) |
| 1206 | return getTruncateOrZeroExtend(SZ->getOperand(), Ty, Depth + 1); |
| 1207 | |
| 1208 | if (Depth > MaxCastDepth) { |
| 1209 | SCEV *S = |
| 1210 | new (SCEVAllocator) SCEVTruncateExpr(ID.Intern(SCEVAllocator), Op, Ty); |
| 1211 | UniqueSCEVs.InsertNode(S, IP); |
| 1212 | addToLoopUseLists(S); |
| 1213 | return S; |
| 1214 | } |
| 1215 | |
| 1216 | // trunc(x1 + ... + xN) --> trunc(x1) + ... + trunc(xN) and |
| 1217 | // trunc(x1 * ... * xN) --> trunc(x1) * ... * trunc(xN), |
| 1218 | // if after transforming we have at most one truncate, not counting truncates |
| 1219 | // that replace other casts. |
| 1220 | if (isa<SCEVAddExpr>(Op) || isa<SCEVMulExpr>(Op)) { |
| 1221 | auto *CommOp = cast<SCEVCommutativeExpr>(Op); |
| 1222 | SmallVector<const SCEV *, 4> Operands; |
| 1223 | unsigned numTruncs = 0; |
| 1224 | for (unsigned i = 0, e = CommOp->getNumOperands(); i != e && numTruncs < 2; |
| 1225 | ++i) { |
| 1226 | const SCEV *S = getTruncateExpr(CommOp->getOperand(i), Ty, Depth + 1); |
| 1227 | if (!isa<SCEVIntegralCastExpr>(CommOp->getOperand(i)) && |
| 1228 | isa<SCEVTruncateExpr>(S)) |
| 1229 | numTruncs++; |
| 1230 | Operands.push_back(S); |
| 1231 | } |
| 1232 | if (numTruncs < 2) { |
| 1233 | if (isa<SCEVAddExpr>(Op)) |
| 1234 | return getAddExpr(Operands); |
| 1235 | else if (isa<SCEVMulExpr>(Op)) |
| 1236 | return getMulExpr(Operands); |
| 1237 | else |
| 1238 | llvm_unreachable("Unexpected SCEV type for Op.")::llvm::llvm_unreachable_internal("Unexpected SCEV type for Op." , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 1238); |
| 1239 | } |
| 1240 | // Although we checked in the beginning that ID is not in the cache, it is |
| 1241 | // possible that during recursion and different modification ID was inserted |
| 1242 | // into the cache. So if we find it, just return it. |
| 1243 | if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) |
| 1244 | return S; |
| 1245 | } |
| 1246 | |
| 1247 | // If the input value is a chrec scev, truncate the chrec's operands. |
| 1248 | if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(Op)) { |
| 1249 | SmallVector<const SCEV *, 4> Operands; |
| 1250 | for (const SCEV *Op : AddRec->operands()) |
| 1251 | Operands.push_back(getTruncateExpr(Op, Ty, Depth + 1)); |
| 1252 | return getAddRecExpr(Operands, AddRec->getLoop(), SCEV::FlagAnyWrap); |
| 1253 | } |
| 1254 | |
| 1255 | // Return zero if truncating to known zeros. |
| 1256 | uint32_t MinTrailingZeros = GetMinTrailingZeros(Op); |
| 1257 | if (MinTrailingZeros >= getTypeSizeInBits(Ty)) |
| 1258 | return getZero(Ty); |
| 1259 | |
| 1260 | // The cast wasn't folded; create an explicit cast node. We can reuse |
| 1261 | // the existing insert position since if we get here, we won't have |
| 1262 | // made any changes which would invalidate it. |
| 1263 | SCEV *S = new (SCEVAllocator) SCEVTruncateExpr(ID.Intern(SCEVAllocator), |
| 1264 | Op, Ty); |
| 1265 | UniqueSCEVs.InsertNode(S, IP); |
| 1266 | addToLoopUseLists(S); |
| 1267 | return S; |
| 1268 | } |
| 1269 | |
| 1270 | // Get the limit of a recurrence such that incrementing by Step cannot cause |
| 1271 | // signed overflow as long as the value of the recurrence within the |
| 1272 | // loop does not exceed this limit before incrementing. |
| 1273 | static const SCEV *getSignedOverflowLimitForStep(const SCEV *Step, |
| 1274 | ICmpInst::Predicate *Pred, |
| 1275 | ScalarEvolution *SE) { |
| 1276 | unsigned BitWidth = SE->getTypeSizeInBits(Step->getType()); |
| 1277 | if (SE->isKnownPositive(Step)) { |
| 1278 | *Pred = ICmpInst::ICMP_SLT; |
| 1279 | return SE->getConstant(APInt::getSignedMinValue(BitWidth) - |
| 1280 | SE->getSignedRangeMax(Step)); |
| 1281 | } |
| 1282 | if (SE->isKnownNegative(Step)) { |
| 1283 | *Pred = ICmpInst::ICMP_SGT; |
| 1284 | return SE->getConstant(APInt::getSignedMaxValue(BitWidth) - |
| 1285 | SE->getSignedRangeMin(Step)); |
| 1286 | } |
| 1287 | return nullptr; |
| 1288 | } |
| 1289 | |
| 1290 | // Get the limit of a recurrence such that incrementing by Step cannot cause |
| 1291 | // unsigned overflow as long as the value of the recurrence within the loop does |
| 1292 | // not exceed this limit before incrementing. |
| 1293 | static const SCEV *getUnsignedOverflowLimitForStep(const SCEV *Step, |
| 1294 | ICmpInst::Predicate *Pred, |
| 1295 | ScalarEvolution *SE) { |
| 1296 | unsigned BitWidth = SE->getTypeSizeInBits(Step->getType()); |
| 1297 | *Pred = ICmpInst::ICMP_ULT; |
| 1298 | |
| 1299 | return SE->getConstant(APInt::getMinValue(BitWidth) - |
| 1300 | SE->getUnsignedRangeMax(Step)); |
| 1301 | } |
| 1302 | |
| 1303 | namespace { |
| 1304 | |
| 1305 | struct ExtendOpTraitsBase { |
| 1306 | typedef const SCEV *(ScalarEvolution::*GetExtendExprTy)(const SCEV *, Type *, |
| 1307 | unsigned); |
| 1308 | }; |
| 1309 | |
| 1310 | // Used to make code generic over signed and unsigned overflow. |
| 1311 | template <typename ExtendOp> struct ExtendOpTraits { |
| 1312 | // Members present: |
| 1313 | // |
| 1314 | // static const SCEV::NoWrapFlags WrapType; |
| 1315 | // |
| 1316 | // static const ExtendOpTraitsBase::GetExtendExprTy GetExtendExpr; |
| 1317 | // |
| 1318 | // static const SCEV *getOverflowLimitForStep(const SCEV *Step, |
| 1319 | // ICmpInst::Predicate *Pred, |
| 1320 | // ScalarEvolution *SE); |
| 1321 | }; |
| 1322 | |
| 1323 | template <> |
| 1324 | struct ExtendOpTraits<SCEVSignExtendExpr> : public ExtendOpTraitsBase { |
| 1325 | static const SCEV::NoWrapFlags WrapType = SCEV::FlagNSW; |
| 1326 | |
| 1327 | static const GetExtendExprTy GetExtendExpr; |
| 1328 | |
| 1329 | static const SCEV *getOverflowLimitForStep(const SCEV *Step, |
| 1330 | ICmpInst::Predicate *Pred, |
| 1331 | ScalarEvolution *SE) { |
| 1332 | return getSignedOverflowLimitForStep(Step, Pred, SE); |
| 1333 | } |
| 1334 | }; |
| 1335 | |
| 1336 | const ExtendOpTraitsBase::GetExtendExprTy ExtendOpTraits< |
| 1337 | SCEVSignExtendExpr>::GetExtendExpr = &ScalarEvolution::getSignExtendExpr; |
| 1338 | |
| 1339 | template <> |
| 1340 | struct ExtendOpTraits<SCEVZeroExtendExpr> : public ExtendOpTraitsBase { |
| 1341 | static const SCEV::NoWrapFlags WrapType = SCEV::FlagNUW; |
| 1342 | |
| 1343 | static const GetExtendExprTy GetExtendExpr; |
| 1344 | |
| 1345 | static const SCEV *getOverflowLimitForStep(const SCEV *Step, |
| 1346 | ICmpInst::Predicate *Pred, |
| 1347 | ScalarEvolution *SE) { |
| 1348 | return getUnsignedOverflowLimitForStep(Step, Pred, SE); |
| 1349 | } |
| 1350 | }; |
| 1351 | |
| 1352 | const ExtendOpTraitsBase::GetExtendExprTy ExtendOpTraits< |
| 1353 | SCEVZeroExtendExpr>::GetExtendExpr = &ScalarEvolution::getZeroExtendExpr; |
| 1354 | |
| 1355 | } // end anonymous namespace |
| 1356 | |
| 1357 | // The recurrence AR has been shown to have no signed/unsigned wrap or something |
| 1358 | // close to it. Typically, if we can prove NSW/NUW for AR, then we can just as |
| 1359 | // easily prove NSW/NUW for its preincrement or postincrement sibling. This |
| 1360 | // allows normalizing a sign/zero extended AddRec as such: {sext/zext(Step + |
| 1361 | // Start),+,Step} => {(Step + sext/zext(Start),+,Step} As a result, the |
| 1362 | // expression "Step + sext/zext(PreIncAR)" is congruent with |
| 1363 | // "sext/zext(PostIncAR)" |
| 1364 | template <typename ExtendOpTy> |
| 1365 | static const SCEV *getPreStartForExtend(const SCEVAddRecExpr *AR, Type *Ty, |
| 1366 | ScalarEvolution *SE, unsigned Depth) { |
| 1367 | auto WrapType = ExtendOpTraits<ExtendOpTy>::WrapType; |
| 1368 | auto GetExtendExpr = ExtendOpTraits<ExtendOpTy>::GetExtendExpr; |
| 1369 | |
| 1370 | const Loop *L = AR->getLoop(); |
| 1371 | const SCEV *Start = AR->getStart(); |
| 1372 | const SCEV *Step = AR->getStepRecurrence(*SE); |
| 1373 | |
| 1374 | // Check for a simple looking step prior to loop entry. |
| 1375 | const SCEVAddExpr *SA = dyn_cast<SCEVAddExpr>(Start); |
| 1376 | if (!SA) |
| 1377 | return nullptr; |
| 1378 | |
| 1379 | // Create an AddExpr for "PreStart" after subtracting Step. Full SCEV |
| 1380 | // subtraction is expensive. For this purpose, perform a quick and dirty |
| 1381 | // difference, by checking for Step in the operand list. |
| 1382 | SmallVector<const SCEV *, 4> DiffOps; |
| 1383 | for (const SCEV *Op : SA->operands()) |
| 1384 | if (Op != Step) |
| 1385 | DiffOps.push_back(Op); |
| 1386 | |
| 1387 | if (DiffOps.size() == SA->getNumOperands()) |
| 1388 | return nullptr; |
| 1389 | |
| 1390 | // Try to prove `WrapType` (SCEV::FlagNSW or SCEV::FlagNUW) on `PreStart` + |
| 1391 | // `Step`: |
| 1392 | |
| 1393 | // 1. NSW/NUW flags on the step increment. |
| 1394 | auto PreStartFlags = |
| 1395 | ScalarEvolution::maskFlags(SA->getNoWrapFlags(), SCEV::FlagNUW); |
| 1396 | const SCEV *PreStart = SE->getAddExpr(DiffOps, PreStartFlags); |
| 1397 | const SCEVAddRecExpr *PreAR = dyn_cast<SCEVAddRecExpr>( |
| 1398 | SE->getAddRecExpr(PreStart, Step, L, SCEV::FlagAnyWrap)); |
| 1399 | |
| 1400 | // "{S,+,X} is <nsw>/<nuw>" and "the backedge is taken at least once" implies |
| 1401 | // "S+X does not sign/unsign-overflow". |
| 1402 | // |
| 1403 | |
| 1404 | const SCEV *BECount = SE->getBackedgeTakenCount(L); |
| 1405 | if (PreAR && PreAR->getNoWrapFlags(WrapType) && |
| 1406 | !isa<SCEVCouldNotCompute>(BECount) && SE->isKnownPositive(BECount)) |
| 1407 | return PreStart; |
| 1408 | |
| 1409 | // 2. Direct overflow check on the step operation's expression. |
| 1410 | unsigned BitWidth = SE->getTypeSizeInBits(AR->getType()); |
| 1411 | Type *WideTy = IntegerType::get(SE->getContext(), BitWidth * 2); |
| 1412 | const SCEV *OperandExtendedStart = |
| 1413 | SE->getAddExpr((SE->*GetExtendExpr)(PreStart, WideTy, Depth), |
| 1414 | (SE->*GetExtendExpr)(Step, WideTy, Depth)); |
| 1415 | if ((SE->*GetExtendExpr)(Start, WideTy, Depth) == OperandExtendedStart) { |
| 1416 | if (PreAR && AR->getNoWrapFlags(WrapType)) { |
| 1417 | // If we know `AR` == {`PreStart`+`Step`,+,`Step`} is `WrapType` (FlagNSW |
| 1418 | // or FlagNUW) and that `PreStart` + `Step` is `WrapType` too, then |
| 1419 | // `PreAR` == {`PreStart`,+,`Step`} is also `WrapType`. Cache this fact. |
| 1420 | SE->setNoWrapFlags(const_cast<SCEVAddRecExpr *>(PreAR), WrapType); |
| 1421 | } |
| 1422 | return PreStart; |
| 1423 | } |
| 1424 | |
| 1425 | // 3. Loop precondition. |
| 1426 | ICmpInst::Predicate Pred; |
| 1427 | const SCEV *OverflowLimit = |
| 1428 | ExtendOpTraits<ExtendOpTy>::getOverflowLimitForStep(Step, &Pred, SE); |
| 1429 | |
| 1430 | if (OverflowLimit && |
| 1431 | SE->isLoopEntryGuardedByCond(L, Pred, PreStart, OverflowLimit)) |
| 1432 | return PreStart; |
| 1433 | |
| 1434 | return nullptr; |
| 1435 | } |
| 1436 | |
| 1437 | // Get the normalized zero or sign extended expression for this AddRec's Start. |
| 1438 | template <typename ExtendOpTy> |
| 1439 | static const SCEV *getExtendAddRecStart(const SCEVAddRecExpr *AR, Type *Ty, |
| 1440 | ScalarEvolution *SE, |
| 1441 | unsigned Depth) { |
| 1442 | auto GetExtendExpr = ExtendOpTraits<ExtendOpTy>::GetExtendExpr; |
| 1443 | |
| 1444 | const SCEV *PreStart = getPreStartForExtend<ExtendOpTy>(AR, Ty, SE, Depth); |
| 1445 | if (!PreStart) |
| 1446 | return (SE->*GetExtendExpr)(AR->getStart(), Ty, Depth); |
| 1447 | |
| 1448 | return SE->getAddExpr((SE->*GetExtendExpr)(AR->getStepRecurrence(*SE), Ty, |
| 1449 | Depth), |
| 1450 | (SE->*GetExtendExpr)(PreStart, Ty, Depth)); |
| 1451 | } |
| 1452 | |
| 1453 | // Try to prove away overflow by looking at "nearby" add recurrences. A |
| 1454 | // motivating example for this rule: if we know `{0,+,4}` is `ult` `-1` and it |
| 1455 | // does not itself wrap then we can conclude that `{1,+,4}` is `nuw`. |
| 1456 | // |
| 1457 | // Formally: |
| 1458 | // |
| 1459 | // {S,+,X} == {S-T,+,X} + T |
| 1460 | // => Ext({S,+,X}) == Ext({S-T,+,X} + T) |
| 1461 | // |
| 1462 | // If ({S-T,+,X} + T) does not overflow ... (1) |
| 1463 | // |
| 1464 | // RHS == Ext({S-T,+,X} + T) == Ext({S-T,+,X}) + Ext(T) |
| 1465 | // |
| 1466 | // If {S-T,+,X} does not overflow ... (2) |
| 1467 | // |
| 1468 | // RHS == Ext({S-T,+,X}) + Ext(T) == {Ext(S-T),+,Ext(X)} + Ext(T) |
| 1469 | // == {Ext(S-T)+Ext(T),+,Ext(X)} |
| 1470 | // |
| 1471 | // If (S-T)+T does not overflow ... (3) |
| 1472 | // |
| 1473 | // RHS == {Ext(S-T)+Ext(T),+,Ext(X)} == {Ext(S-T+T),+,Ext(X)} |
| 1474 | // == {Ext(S),+,Ext(X)} == LHS |
| 1475 | // |
| 1476 | // Thus, if (1), (2) and (3) are true for some T, then |
| 1477 | // Ext({S,+,X}) == {Ext(S),+,Ext(X)} |
| 1478 | // |
| 1479 | // (3) is implied by (1) -- "(S-T)+T does not overflow" is simply "({S-T,+,X}+T) |
| 1480 | // does not overflow" restricted to the 0th iteration. Therefore we only need |
| 1481 | // to check for (1) and (2). |
| 1482 | // |
| 1483 | // In the current context, S is `Start`, X is `Step`, Ext is `ExtendOpTy` and T |
| 1484 | // is `Delta` (defined below). |
| 1485 | template <typename ExtendOpTy> |
| 1486 | bool ScalarEvolution::proveNoWrapByVaryingStart(const SCEV *Start, |
| 1487 | const SCEV *Step, |
| 1488 | const Loop *L) { |
| 1489 | auto WrapType = ExtendOpTraits<ExtendOpTy>::WrapType; |
| 1490 | |
| 1491 | // We restrict `Start` to a constant to prevent SCEV from spending too much |
| 1492 | // time here. It is correct (but more expensive) to continue with a |
| 1493 | // non-constant `Start` and do a general SCEV subtraction to compute |
| 1494 | // `PreStart` below. |
| 1495 | const SCEVConstant *StartC = dyn_cast<SCEVConstant>(Start); |
| 1496 | if (!StartC) |
| 1497 | return false; |
| 1498 | |
| 1499 | APInt StartAI = StartC->getAPInt(); |
| 1500 | |
| 1501 | for (unsigned Delta : {-2, -1, 1, 2}) { |
| 1502 | const SCEV *PreStart = getConstant(StartAI - Delta); |
| 1503 | |
| 1504 | FoldingSetNodeID ID; |
| 1505 | ID.AddInteger(scAddRecExpr); |
| 1506 | ID.AddPointer(PreStart); |
| 1507 | ID.AddPointer(Step); |
| 1508 | ID.AddPointer(L); |
| 1509 | void *IP = nullptr; |
| 1510 | const auto *PreAR = |
| 1511 | static_cast<SCEVAddRecExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP)); |
| 1512 | |
| 1513 | // Give up if we don't already have the add recurrence we need because |
| 1514 | // actually constructing an add recurrence is relatively expensive. |
| 1515 | if (PreAR && PreAR->getNoWrapFlags(WrapType)) { // proves (2) |
| 1516 | const SCEV *DeltaS = getConstant(StartC->getType(), Delta); |
| 1517 | ICmpInst::Predicate Pred = ICmpInst::BAD_ICMP_PREDICATE; |
| 1518 | const SCEV *Limit = ExtendOpTraits<ExtendOpTy>::getOverflowLimitForStep( |
| 1519 | DeltaS, &Pred, this); |
| 1520 | if (Limit && isKnownPredicate(Pred, PreAR, Limit)) // proves (1) |
| 1521 | return true; |
| 1522 | } |
| 1523 | } |
| 1524 | |
| 1525 | return false; |
| 1526 | } |
| 1527 | |
| 1528 | // Finds an integer D for an expression (C + x + y + ...) such that the top |
| 1529 | // level addition in (D + (C - D + x + y + ...)) would not wrap (signed or |
| 1530 | // unsigned) and the number of trailing zeros of (C - D + x + y + ...) is |
| 1531 | // maximized, where C is the \p ConstantTerm, x, y, ... are arbitrary SCEVs, and |
| 1532 | // the (C + x + y + ...) expression is \p WholeAddExpr. |
| 1533 | static APInt extractConstantWithoutWrapping(ScalarEvolution &SE, |
| 1534 | const SCEVConstant *ConstantTerm, |
| 1535 | const SCEVAddExpr *WholeAddExpr) { |
| 1536 | const APInt &C = ConstantTerm->getAPInt(); |
| 1537 | const unsigned BitWidth = C.getBitWidth(); |
| 1538 | // Find number of trailing zeros of (x + y + ...) w/o the C first: |
| 1539 | uint32_t TZ = BitWidth; |
| 1540 | for (unsigned I = 1, E = WholeAddExpr->getNumOperands(); I < E && TZ; ++I) |
| 1541 | TZ = std::min(TZ, SE.GetMinTrailingZeros(WholeAddExpr->getOperand(I))); |
| 1542 | if (TZ) { |
| 1543 | // Set D to be as many least significant bits of C as possible while still |
| 1544 | // guaranteeing that adding D to (C - D + x + y + ...) won't cause a wrap: |
| 1545 | return TZ < BitWidth ? C.trunc(TZ).zext(BitWidth) : C; |
| 1546 | } |
| 1547 | return APInt(BitWidth, 0); |
| 1548 | } |
| 1549 | |
| 1550 | // Finds an integer D for an affine AddRec expression {C,+,x} such that the top |
| 1551 | // level addition in (D + {C-D,+,x}) would not wrap (signed or unsigned) and the |
| 1552 | // number of trailing zeros of (C - D + x * n) is maximized, where C is the \p |
| 1553 | // ConstantStart, x is an arbitrary \p Step, and n is the loop trip count. |
| 1554 | static APInt extractConstantWithoutWrapping(ScalarEvolution &SE, |
| 1555 | const APInt &ConstantStart, |
| 1556 | const SCEV *Step) { |
| 1557 | const unsigned BitWidth = ConstantStart.getBitWidth(); |
| 1558 | const uint32_t TZ = SE.GetMinTrailingZeros(Step); |
| 1559 | if (TZ) |
| 1560 | return TZ < BitWidth ? ConstantStart.trunc(TZ).zext(BitWidth) |
| 1561 | : ConstantStart; |
| 1562 | return APInt(BitWidth, 0); |
| 1563 | } |
| 1564 | |
| 1565 | const SCEV * |
| 1566 | ScalarEvolution::getZeroExtendExpr(const SCEV *Op, Type *Ty, unsigned Depth) { |
| 1567 | assert(getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) &&(static_cast <bool> (getTypeSizeInBits(Op->getType() ) < getTypeSizeInBits(Ty) && "This is not an extending conversion!" ) ? void (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 1568, __extension__ __PRETTY_FUNCTION__)) |
| 1568 | "This is not an extending conversion!")(static_cast <bool> (getTypeSizeInBits(Op->getType() ) < getTypeSizeInBits(Ty) && "This is not an extending conversion!" ) ? void (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 1568, __extension__ __PRETTY_FUNCTION__)); |
| 1569 | assert(isSCEVable(Ty) &&(static_cast <bool> (isSCEVable(Ty) && "This is not a conversion to a SCEVable type!" ) ? void (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 1570, __extension__ __PRETTY_FUNCTION__)) |
| 1570 | "This is not a conversion to a SCEVable type!")(static_cast <bool> (isSCEVable(Ty) && "This is not a conversion to a SCEVable type!" ) ? void (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 1570, __extension__ __PRETTY_FUNCTION__)); |
| 1571 | Ty = getEffectiveSCEVType(Ty); |
| 1572 | |
| 1573 | // Fold if the operand is constant. |
| 1574 | if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op)) |
| 1575 | return getConstant( |
| 1576 | cast<ConstantInt>(ConstantExpr::getZExt(SC->getValue(), Ty))); |
| 1577 | |
| 1578 | // zext(zext(x)) --> zext(x) |
| 1579 | if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op)) |
| 1580 | return getZeroExtendExpr(SZ->getOperand(), Ty, Depth + 1); |
| 1581 | |
| 1582 | // Before doing any expensive analysis, check to see if we've already |
| 1583 | // computed a SCEV for this Op and Ty. |
| 1584 | FoldingSetNodeID ID; |
| 1585 | ID.AddInteger(scZeroExtend); |
| 1586 | ID.AddPointer(Op); |
| 1587 | ID.AddPointer(Ty); |
| 1588 | void *IP = nullptr; |
| 1589 | if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S; |
| 1590 | if (Depth > MaxCastDepth) { |
| 1591 | SCEV *S = new (SCEVAllocator) SCEVZeroExtendExpr(ID.Intern(SCEVAllocator), |
| 1592 | Op, Ty); |
| 1593 | UniqueSCEVs.InsertNode(S, IP); |
| 1594 | addToLoopUseLists(S); |
| 1595 | return S; |
| 1596 | } |
| 1597 | |
| 1598 | // zext(trunc(x)) --> zext(x) or x or trunc(x) |
| 1599 | if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op)) { |
| 1600 | // It's possible the bits taken off by the truncate were all zero bits. If |
| 1601 | // so, we should be able to simplify this further. |
| 1602 | const SCEV *X = ST->getOperand(); |
| 1603 | ConstantRange CR = getUnsignedRange(X); |
| 1604 | unsigned TruncBits = getTypeSizeInBits(ST->getType()); |
| 1605 | unsigned NewBits = getTypeSizeInBits(Ty); |
| 1606 | if (CR.truncate(TruncBits).zeroExtend(NewBits).contains( |
| 1607 | CR.zextOrTrunc(NewBits))) |
| 1608 | return getTruncateOrZeroExtend(X, Ty, Depth); |
| 1609 | } |
| 1610 | |
| 1611 | // If the input value is a chrec scev, and we can prove that the value |
| 1612 | // did not overflow the old, smaller, value, we can zero extend all of the |
| 1613 | // operands (often constants). This allows analysis of something like |
| 1614 | // this: for (unsigned char X = 0; X < 100; ++X) { int Y = X; } |
| 1615 | if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op)) |
| 1616 | if (AR->isAffine()) { |
| 1617 | const SCEV *Start = AR->getStart(); |
| 1618 | const SCEV *Step = AR->getStepRecurrence(*this); |
| 1619 | unsigned BitWidth = getTypeSizeInBits(AR->getType()); |
| 1620 | const Loop *L = AR->getLoop(); |
| 1621 | |
| 1622 | if (!AR->hasNoUnsignedWrap()) { |
| 1623 | auto NewFlags = proveNoWrapViaConstantRanges(AR); |
| 1624 | setNoWrapFlags(const_cast<SCEVAddRecExpr *>(AR), NewFlags); |
| 1625 | } |
| 1626 | |
| 1627 | // If we have special knowledge that this addrec won't overflow, |
| 1628 | // we don't need to do any further analysis. |
| 1629 | if (AR->hasNoUnsignedWrap()) |
| 1630 | return getAddRecExpr( |
| 1631 | getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, Depth + 1), |
| 1632 | getZeroExtendExpr(Step, Ty, Depth + 1), L, AR->getNoWrapFlags()); |
| 1633 | |
| 1634 | // Check whether the backedge-taken count is SCEVCouldNotCompute. |
| 1635 | // Note that this serves two purposes: It filters out loops that are |
| 1636 | // simply not analyzable, and it covers the case where this code is |
| 1637 | // being called from within backedge-taken count analysis, such that |
| 1638 | // attempting to ask for the backedge-taken count would likely result |
| 1639 | // in infinite recursion. In the later case, the analysis code will |
| 1640 | // cope with a conservative value, and it will take care to purge |
| 1641 | // that value once it has finished. |
| 1642 | const SCEV *MaxBECount = getConstantMaxBackedgeTakenCount(L); |
| 1643 | if (!isa<SCEVCouldNotCompute>(MaxBECount)) { |
| 1644 | // Manually compute the final value for AR, checking for overflow. |
| 1645 | |
| 1646 | // Check whether the backedge-taken count can be losslessly casted to |
| 1647 | // the addrec's type. The count is always unsigned. |
| 1648 | const SCEV *CastedMaxBECount = |
| 1649 | getTruncateOrZeroExtend(MaxBECount, Start->getType(), Depth); |
| 1650 | const SCEV *RecastedMaxBECount = getTruncateOrZeroExtend( |
| 1651 | CastedMaxBECount, MaxBECount->getType(), Depth); |
| 1652 | if (MaxBECount == RecastedMaxBECount) { |
| 1653 | Type *WideTy = IntegerType::get(getContext(), BitWidth * 2); |
| 1654 | // Check whether Start+Step*MaxBECount has no unsigned overflow. |
| 1655 | const SCEV *ZMul = getMulExpr(CastedMaxBECount, Step, |
| 1656 | SCEV::FlagAnyWrap, Depth + 1); |
| 1657 | const SCEV *ZAdd = getZeroExtendExpr(getAddExpr(Start, ZMul, |
| 1658 | SCEV::FlagAnyWrap, |
| 1659 | Depth + 1), |
| 1660 | WideTy, Depth + 1); |
| 1661 | const SCEV *WideStart = getZeroExtendExpr(Start, WideTy, Depth + 1); |
| 1662 | const SCEV *WideMaxBECount = |
| 1663 | getZeroExtendExpr(CastedMaxBECount, WideTy, Depth + 1); |
| 1664 | const SCEV *OperandExtendedAdd = |
| 1665 | getAddExpr(WideStart, |
| 1666 | getMulExpr(WideMaxBECount, |
| 1667 | getZeroExtendExpr(Step, WideTy, Depth + 1), |
| 1668 | SCEV::FlagAnyWrap, Depth + 1), |
| 1669 | SCEV::FlagAnyWrap, Depth + 1); |
| 1670 | if (ZAdd == OperandExtendedAdd) { |
| 1671 | // Cache knowledge of AR NUW, which is propagated to this AddRec. |
| 1672 | setNoWrapFlags(const_cast<SCEVAddRecExpr *>(AR), SCEV::FlagNUW); |
| 1673 | // Return the expression with the addrec on the outside. |
| 1674 | return getAddRecExpr( |
| 1675 | getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, |
| 1676 | Depth + 1), |
| 1677 | getZeroExtendExpr(Step, Ty, Depth + 1), L, |
| 1678 | AR->getNoWrapFlags()); |
| 1679 | } |
| 1680 | // Similar to above, only this time treat the step value as signed. |
| 1681 | // This covers loops that count down. |
| 1682 | OperandExtendedAdd = |
| 1683 | getAddExpr(WideStart, |
| 1684 | getMulExpr(WideMaxBECount, |
| 1685 | getSignExtendExpr(Step, WideTy, Depth + 1), |
| 1686 | SCEV::FlagAnyWrap, Depth + 1), |
| 1687 | SCEV::FlagAnyWrap, Depth + 1); |
| 1688 | if (ZAdd == OperandExtendedAdd) { |
| 1689 | // Cache knowledge of AR NW, which is propagated to this AddRec. |
| 1690 | // Negative step causes unsigned wrap, but it still can't self-wrap. |
| 1691 | setNoWrapFlags(const_cast<SCEVAddRecExpr *>(AR), SCEV::FlagNW); |
| 1692 | // Return the expression with the addrec on the outside. |
| 1693 | return getAddRecExpr( |
| 1694 | getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, |
| 1695 | Depth + 1), |
| 1696 | getSignExtendExpr(Step, Ty, Depth + 1), L, |
| 1697 | AR->getNoWrapFlags()); |
| 1698 | } |
| 1699 | } |
| 1700 | } |
| 1701 | |
| 1702 | // Normally, in the cases we can prove no-overflow via a |
| 1703 | // backedge guarding condition, we can also compute a backedge |
| 1704 | // taken count for the loop. The exceptions are assumptions and |
| 1705 | // guards present in the loop -- SCEV is not great at exploiting |
| 1706 | // these to compute max backedge taken counts, but can still use |
| 1707 | // these to prove lack of overflow. Use this fact to avoid |
| 1708 | // doing extra work that may not pay off. |
| 1709 | if (!isa<SCEVCouldNotCompute>(MaxBECount) || HasGuards || |
| 1710 | !AC.assumptions().empty()) { |
| 1711 | |
| 1712 | auto NewFlags = proveNoUnsignedWrapViaInduction(AR); |
| 1713 | setNoWrapFlags(const_cast<SCEVAddRecExpr *>(AR), NewFlags); |
| 1714 | if (AR->hasNoUnsignedWrap()) { |
| 1715 | // Same as nuw case above - duplicated here to avoid a compile time |
| 1716 | // issue. It's not clear that the order of checks does matter, but |
| 1717 | // it's one of two issue possible causes for a change which was |
| 1718 | // reverted. Be conservative for the moment. |
| 1719 | return getAddRecExpr( |
| 1720 | getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, |
| 1721 | Depth + 1), |
| 1722 | getZeroExtendExpr(Step, Ty, Depth + 1), L, |
| 1723 | AR->getNoWrapFlags()); |
| 1724 | } |
| 1725 | |
| 1726 | // For a negative step, we can extend the operands iff doing so only |
| 1727 | // traverses values in the range zext([0,UINT_MAX]). |
| 1728 | if (isKnownNegative(Step)) { |
| 1729 | const SCEV *N = getConstant(APInt::getMaxValue(BitWidth) - |
| 1730 | getSignedRangeMin(Step)); |
| 1731 | if (isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_UGT, AR, N) || |
| 1732 | isKnownOnEveryIteration(ICmpInst::ICMP_UGT, AR, N)) { |
| 1733 | // Cache knowledge of AR NW, which is propagated to this |
| 1734 | // AddRec. Negative step causes unsigned wrap, but it |
| 1735 | // still can't self-wrap. |
| 1736 | setNoWrapFlags(const_cast<SCEVAddRecExpr *>(AR), SCEV::FlagNW); |
| 1737 | // Return the expression with the addrec on the outside. |
| 1738 | return getAddRecExpr( |
| 1739 | getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, |
| 1740 | Depth + 1), |
| 1741 | getSignExtendExpr(Step, Ty, Depth + 1), L, |
| 1742 | AR->getNoWrapFlags()); |
| 1743 | } |
| 1744 | } |
| 1745 | } |
| 1746 | |
| 1747 | // zext({C,+,Step}) --> (zext(D) + zext({C-D,+,Step}))<nuw><nsw> |
| 1748 | // if D + (C - D + Step * n) could be proven to not unsigned wrap |
| 1749 | // where D maximizes the number of trailing zeros of (C - D + Step * n) |
| 1750 | if (const auto *SC = dyn_cast<SCEVConstant>(Start)) { |
| 1751 | const APInt &C = SC->getAPInt(); |
| 1752 | const APInt &D = extractConstantWithoutWrapping(*this, C, Step); |
| 1753 | if (D != 0) { |
| 1754 | const SCEV *SZExtD = getZeroExtendExpr(getConstant(D), Ty, Depth); |
| 1755 | const SCEV *SResidual = |
| 1756 | getAddRecExpr(getConstant(C - D), Step, L, AR->getNoWrapFlags()); |
| 1757 | const SCEV *SZExtR = getZeroExtendExpr(SResidual, Ty, Depth + 1); |
| 1758 | return getAddExpr(SZExtD, SZExtR, |
| 1759 | (SCEV::NoWrapFlags)(SCEV::FlagNSW | SCEV::FlagNUW), |
| 1760 | Depth + 1); |
| 1761 | } |
| 1762 | } |
| 1763 | |
| 1764 | if (proveNoWrapByVaryingStart<SCEVZeroExtendExpr>(Start, Step, L)) { |
| 1765 | setNoWrapFlags(const_cast<SCEVAddRecExpr *>(AR), SCEV::FlagNUW); |
| 1766 | return getAddRecExpr( |
| 1767 | getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, Depth + 1), |
| 1768 | getZeroExtendExpr(Step, Ty, Depth + 1), L, AR->getNoWrapFlags()); |
| 1769 | } |
| 1770 | } |
| 1771 | |
| 1772 | // zext(A % B) --> zext(A) % zext(B) |
| 1773 | { |
| 1774 | const SCEV *LHS; |
| 1775 | const SCEV *RHS; |
| 1776 | if (matchURem(Op, LHS, RHS)) |
| 1777 | return getURemExpr(getZeroExtendExpr(LHS, Ty, Depth + 1), |
| 1778 | getZeroExtendExpr(RHS, Ty, Depth + 1)); |
| 1779 | } |
| 1780 | |
| 1781 | // zext(A / B) --> zext(A) / zext(B). |
| 1782 | if (auto *Div = dyn_cast<SCEVUDivExpr>(Op)) |
| 1783 | return getUDivExpr(getZeroExtendExpr(Div->getLHS(), Ty, Depth + 1), |
| 1784 | getZeroExtendExpr(Div->getRHS(), Ty, Depth + 1)); |
| 1785 | |
| 1786 | if (auto *SA = dyn_cast<SCEVAddExpr>(Op)) { |
| 1787 | // zext((A + B + ...)<nuw>) --> (zext(A) + zext(B) + ...)<nuw> |
| 1788 | if (SA->hasNoUnsignedWrap()) { |
| 1789 | // If the addition does not unsign overflow then we can, by definition, |
| 1790 | // commute the zero extension with the addition operation. |
| 1791 | SmallVector<const SCEV *, 4> Ops; |
| 1792 | for (const auto *Op : SA->operands()) |
| 1793 | Ops.push_back(getZeroExtendExpr(Op, Ty, Depth + 1)); |
| 1794 | return getAddExpr(Ops, SCEV::FlagNUW, Depth + 1); |
| 1795 | } |
| 1796 | |
| 1797 | // zext(C + x + y + ...) --> (zext(D) + zext((C - D) + x + y + ...)) |
| 1798 | // if D + (C - D + x + y + ...) could be proven to not unsigned wrap |
| 1799 | // where D maximizes the number of trailing zeros of (C - D + x + y + ...) |
| 1800 | // |
| 1801 | // Often address arithmetics contain expressions like |
| 1802 | // (zext (add (shl X, C1), C2)), for instance, (zext (5 + (4 * X))). |
| 1803 | // This transformation is useful while proving that such expressions are |
| 1804 | // equal or differ by a small constant amount, see LoadStoreVectorizer pass. |
| 1805 | if (const auto *SC = dyn_cast<SCEVConstant>(SA->getOperand(0))) { |
| 1806 | const APInt &D = extractConstantWithoutWrapping(*this, SC, SA); |
| 1807 | if (D != 0) { |
| 1808 | const SCEV *SZExtD = getZeroExtendExpr(getConstant(D), Ty, Depth); |
| 1809 | const SCEV *SResidual = |
| 1810 | getAddExpr(getConstant(-D), SA, SCEV::FlagAnyWrap, Depth); |
| 1811 | const SCEV *SZExtR = getZeroExtendExpr(SResidual, Ty, Depth + 1); |
| 1812 | return getAddExpr(SZExtD, SZExtR, |
| 1813 | (SCEV::NoWrapFlags)(SCEV::FlagNSW | SCEV::FlagNUW), |
| 1814 | Depth + 1); |
| 1815 | } |
| 1816 | } |
| 1817 | } |
| 1818 | |
| 1819 | if (auto *SM = dyn_cast<SCEVMulExpr>(Op)) { |
| 1820 | // zext((A * B * ...)<nuw>) --> (zext(A) * zext(B) * ...)<nuw> |
| 1821 | if (SM->hasNoUnsignedWrap()) { |
| 1822 | // If the multiply does not unsign overflow then we can, by definition, |
| 1823 | // commute the zero extension with the multiply operation. |
| 1824 | SmallVector<const SCEV *, 4> Ops; |
| 1825 | for (const auto *Op : SM->operands()) |
| 1826 | Ops.push_back(getZeroExtendExpr(Op, Ty, Depth + 1)); |
| 1827 | return getMulExpr(Ops, SCEV::FlagNUW, Depth + 1); |
| 1828 | } |
| 1829 | |
| 1830 | // zext(2^K * (trunc X to iN)) to iM -> |
| 1831 | // 2^K * (zext(trunc X to i{N-K}) to iM)<nuw> |
| 1832 | // |
| 1833 | // Proof: |
| 1834 | // |
| 1835 | // zext(2^K * (trunc X to iN)) to iM |
| 1836 | // = zext((trunc X to iN) << K) to iM |
| 1837 | // = zext((trunc X to i{N-K}) << K)<nuw> to iM |
| 1838 | // (because shl removes the top K bits) |
| 1839 | // = zext((2^K * (trunc X to i{N-K}))<nuw>) to iM |
| 1840 | // = (2^K * (zext(trunc X to i{N-K}) to iM))<nuw>. |
| 1841 | // |
| 1842 | if (SM->getNumOperands() == 2) |
| 1843 | if (auto *MulLHS = dyn_cast<SCEVConstant>(SM->getOperand(0))) |
| 1844 | if (MulLHS->getAPInt().isPowerOf2()) |
| 1845 | if (auto *TruncRHS = dyn_cast<SCEVTruncateExpr>(SM->getOperand(1))) { |
| 1846 | int NewTruncBits = getTypeSizeInBits(TruncRHS->getType()) - |
| 1847 | MulLHS->getAPInt().logBase2(); |
| 1848 | Type *NewTruncTy = IntegerType::get(getContext(), NewTruncBits); |
| 1849 | return getMulExpr( |
| 1850 | getZeroExtendExpr(MulLHS, Ty), |
| 1851 | getZeroExtendExpr( |
| 1852 | getTruncateExpr(TruncRHS->getOperand(), NewTruncTy), Ty), |
| 1853 | SCEV::FlagNUW, Depth + 1); |
| 1854 | } |
| 1855 | } |
| 1856 | |
| 1857 | // The cast wasn't folded; create an explicit cast node. |
| 1858 | // Recompute the insert position, as it may have been invalidated. |
| 1859 | if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S; |
| 1860 | SCEV *S = new (SCEVAllocator) SCEVZeroExtendExpr(ID.Intern(SCEVAllocator), |
| 1861 | Op, Ty); |
| 1862 | UniqueSCEVs.InsertNode(S, IP); |
| 1863 | addToLoopUseLists(S); |
| 1864 | return S; |
| 1865 | } |
| 1866 | |
| 1867 | const SCEV * |
| 1868 | ScalarEvolution::getSignExtendExpr(const SCEV *Op, Type *Ty, unsigned Depth) { |
| 1869 | assert(getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) &&(static_cast <bool> (getTypeSizeInBits(Op->getType() ) < getTypeSizeInBits(Ty) && "This is not an extending conversion!" ) ? void (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 1870, __extension__ __PRETTY_FUNCTION__)) |
| 1870 | "This is not an extending conversion!")(static_cast <bool> (getTypeSizeInBits(Op->getType() ) < getTypeSizeInBits(Ty) && "This is not an extending conversion!" ) ? void (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 1870, __extension__ __PRETTY_FUNCTION__)); |
| 1871 | assert(isSCEVable(Ty) &&(static_cast <bool> (isSCEVable(Ty) && "This is not a conversion to a SCEVable type!" ) ? void (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 1872, __extension__ __PRETTY_FUNCTION__)) |
| 1872 | "This is not a conversion to a SCEVable type!")(static_cast <bool> (isSCEVable(Ty) && "This is not a conversion to a SCEVable type!" ) ? void (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 1872, __extension__ __PRETTY_FUNCTION__)); |
| 1873 | Ty = getEffectiveSCEVType(Ty); |
| 1874 | |
| 1875 | // Fold if the operand is constant. |
| 1876 | if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op)) |
| 1877 | return getConstant( |
| 1878 | cast<ConstantInt>(ConstantExpr::getSExt(SC->getValue(), Ty))); |
| 1879 | |
| 1880 | // sext(sext(x)) --> sext(x) |
| 1881 | if (const SCEVSignExtendExpr *SS = dyn_cast<SCEVSignExtendExpr>(Op)) |
| 1882 | return getSignExtendExpr(SS->getOperand(), Ty, Depth + 1); |
| 1883 | |
| 1884 | // sext(zext(x)) --> zext(x) |
| 1885 | if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op)) |
| 1886 | return getZeroExtendExpr(SZ->getOperand(), Ty, Depth + 1); |
| 1887 | |
| 1888 | // Before doing any expensive analysis, check to see if we've already |
| 1889 | // computed a SCEV for this Op and Ty. |
| 1890 | FoldingSetNodeID ID; |
| 1891 | ID.AddInteger(scSignExtend); |
| 1892 | ID.AddPointer(Op); |
| 1893 | ID.AddPointer(Ty); |
| 1894 | void *IP = nullptr; |
| 1895 | if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S; |
| 1896 | // Limit recursion depth. |
| 1897 | if (Depth > MaxCastDepth) { |
| 1898 | SCEV *S = new (SCEVAllocator) SCEVSignExtendExpr(ID.Intern(SCEVAllocator), |
| 1899 | Op, Ty); |
| 1900 | UniqueSCEVs.InsertNode(S, IP); |
| 1901 | addToLoopUseLists(S); |
| 1902 | return S; |
| 1903 | } |
| 1904 | |
| 1905 | // sext(trunc(x)) --> sext(x) or x or trunc(x) |
| 1906 | if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op)) { |
| 1907 | // It's possible the bits taken off by the truncate were all sign bits. If |
| 1908 | // so, we should be able to simplify this further. |
| 1909 | const SCEV *X = ST->getOperand(); |
| 1910 | ConstantRange CR = getSignedRange(X); |
| 1911 | unsigned TruncBits = getTypeSizeInBits(ST->getType()); |
| 1912 | unsigned NewBits = getTypeSizeInBits(Ty); |
| 1913 | if (CR.truncate(TruncBits).signExtend(NewBits).contains( |
| 1914 | CR.sextOrTrunc(NewBits))) |
| 1915 | return getTruncateOrSignExtend(X, Ty, Depth); |
| 1916 | } |
| 1917 | |
| 1918 | if (auto *SA = dyn_cast<SCEVAddExpr>(Op)) { |
| 1919 | // sext((A + B + ...)<nsw>) --> (sext(A) + sext(B) + ...)<nsw> |
| 1920 | if (SA->hasNoSignedWrap()) { |
| 1921 | // If the addition does not sign overflow then we can, by definition, |
| 1922 | // commute the sign extension with the addition operation. |
| 1923 | SmallVector<const SCEV *, 4> Ops; |
| 1924 | for (const auto *Op : SA->operands()) |
| 1925 | Ops.push_back(getSignExtendExpr(Op, Ty, Depth + 1)); |
| 1926 | return getAddExpr(Ops, SCEV::FlagNSW, Depth + 1); |
| 1927 | } |
| 1928 | |
| 1929 | // sext(C + x + y + ...) --> (sext(D) + sext((C - D) + x + y + ...)) |
| 1930 | // if D + (C - D + x + y + ...) could be proven to not signed wrap |
| 1931 | // where D maximizes the number of trailing zeros of (C - D + x + y + ...) |
| 1932 | // |
| 1933 | // For instance, this will bring two seemingly different expressions: |
| 1934 | // 1 + sext(5 + 20 * %x + 24 * %y) and |
| 1935 | // sext(6 + 20 * %x + 24 * %y) |
| 1936 | // to the same form: |
| 1937 | // 2 + sext(4 + 20 * %x + 24 * %y) |
| 1938 | if (const auto *SC = dyn_cast<SCEVConstant>(SA->getOperand(0))) { |
| 1939 | const APInt &D = extractConstantWithoutWrapping(*this, SC, SA); |
| 1940 | if (D != 0) { |
| 1941 | const SCEV *SSExtD = getSignExtendExpr(getConstant(D), Ty, Depth); |
| 1942 | const SCEV *SResidual = |
| 1943 | getAddExpr(getConstant(-D), SA, SCEV::FlagAnyWrap, Depth); |
| 1944 | const SCEV *SSExtR = getSignExtendExpr(SResidual, Ty, Depth + 1); |
| 1945 | return getAddExpr(SSExtD, SSExtR, |
| 1946 | (SCEV::NoWrapFlags)(SCEV::FlagNSW | SCEV::FlagNUW), |
| 1947 | Depth + 1); |
| 1948 | } |
| 1949 | } |
| 1950 | } |
| 1951 | // If the input value is a chrec scev, and we can prove that the value |
| 1952 | // did not overflow the old, smaller, value, we can sign extend all of the |
| 1953 | // operands (often constants). This allows analysis of something like |
| 1954 | // this: for (signed char X = 0; X < 100; ++X) { int Y = X; } |
| 1955 | if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op)) |
| 1956 | if (AR->isAffine()) { |
| 1957 | const SCEV *Start = AR->getStart(); |
| 1958 | const SCEV *Step = AR->getStepRecurrence(*this); |
| 1959 | unsigned BitWidth = getTypeSizeInBits(AR->getType()); |
| 1960 | const Loop *L = AR->getLoop(); |
| 1961 | |
| 1962 | if (!AR->hasNoSignedWrap()) { |
| 1963 | auto NewFlags = proveNoWrapViaConstantRanges(AR); |
| 1964 | setNoWrapFlags(const_cast<SCEVAddRecExpr *>(AR), NewFlags); |
| 1965 | } |
| 1966 | |
| 1967 | // If we have special knowledge that this addrec won't overflow, |
| 1968 | // we don't need to do any further analysis. |
| 1969 | if (AR->hasNoSignedWrap()) |
| 1970 | return getAddRecExpr( |
| 1971 | getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, Depth + 1), |
| 1972 | getSignExtendExpr(Step, Ty, Depth + 1), L, SCEV::FlagNSW); |
| 1973 | |
| 1974 | // Check whether the backedge-taken count is SCEVCouldNotCompute. |
| 1975 | // Note that this serves two purposes: It filters out loops that are |
| 1976 | // simply not analyzable, and it covers the case where this code is |
| 1977 | // being called from within backedge-taken count analysis, such that |
| 1978 | // attempting to ask for the backedge-taken count would likely result |
| 1979 | // in infinite recursion. In the later case, the analysis code will |
| 1980 | // cope with a conservative value, and it will take care to purge |
| 1981 | // that value once it has finished. |
| 1982 | const SCEV *MaxBECount = getConstantMaxBackedgeTakenCount(L); |
| 1983 | if (!isa<SCEVCouldNotCompute>(MaxBECount)) { |
| 1984 | // Manually compute the final value for AR, checking for |
| 1985 | // overflow. |
| 1986 | |
| 1987 | // Check whether the backedge-taken count can be losslessly casted to |
| 1988 | // the addrec's type. The count is always unsigned. |
| 1989 | const SCEV *CastedMaxBECount = |
| 1990 | getTruncateOrZeroExtend(MaxBECount, Start->getType(), Depth); |
| 1991 | const SCEV *RecastedMaxBECount = getTruncateOrZeroExtend( |
| 1992 | CastedMaxBECount, MaxBECount->getType(), Depth); |
| 1993 | if (MaxBECount == RecastedMaxBECount) { |
| 1994 | Type *WideTy = IntegerType::get(getContext(), BitWidth * 2); |
| 1995 | // Check whether Start+Step*MaxBECount has no signed overflow. |
| 1996 | const SCEV *SMul = getMulExpr(CastedMaxBECount, Step, |
| 1997 | SCEV::FlagAnyWrap, Depth + 1); |
| 1998 | const SCEV *SAdd = getSignExtendExpr(getAddExpr(Start, SMul, |
| 1999 | SCEV::FlagAnyWrap, |
| 2000 | Depth + 1), |
| 2001 | WideTy, Depth + 1); |
| 2002 | const SCEV *WideStart = getSignExtendExpr(Start, WideTy, Depth + 1); |
| 2003 | const SCEV *WideMaxBECount = |
| 2004 | getZeroExtendExpr(CastedMaxBECount, WideTy, Depth + 1); |
| 2005 | const SCEV *OperandExtendedAdd = |
| 2006 | getAddExpr(WideStart, |
| 2007 | getMulExpr(WideMaxBECount, |
| 2008 | getSignExtendExpr(Step, WideTy, Depth + 1), |
| 2009 | SCEV::FlagAnyWrap, Depth + 1), |
| 2010 | SCEV::FlagAnyWrap, Depth + 1); |
| 2011 | if (SAdd == OperandExtendedAdd) { |
| 2012 | // Cache knowledge of AR NSW, which is propagated to this AddRec. |
| 2013 | setNoWrapFlags(const_cast<SCEVAddRecExpr *>(AR), SCEV::FlagNSW); |
| 2014 | // Return the expression with the addrec on the outside. |
| 2015 | return getAddRecExpr( |
| 2016 | getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, |
| 2017 | Depth + 1), |
| 2018 | getSignExtendExpr(Step, Ty, Depth + 1), L, |
| 2019 | AR->getNoWrapFlags()); |
| 2020 | } |
| 2021 | // Similar to above, only this time treat the step value as unsigned. |
| 2022 | // This covers loops that count up with an unsigned step. |
| 2023 | OperandExtendedAdd = |
| 2024 | getAddExpr(WideStart, |
| 2025 | getMulExpr(WideMaxBECount, |
| 2026 | getZeroExtendExpr(Step, WideTy, Depth + 1), |
| 2027 | SCEV::FlagAnyWrap, Depth + 1), |
| 2028 | SCEV::FlagAnyWrap, Depth + 1); |
| 2029 | if (SAdd == OperandExtendedAdd) { |
| 2030 | // If AR wraps around then |
| 2031 | // |
| 2032 | // abs(Step) * MaxBECount > unsigned-max(AR->getType()) |
| 2033 | // => SAdd != OperandExtendedAdd |
| 2034 | // |
| 2035 | // Thus (AR is not NW => SAdd != OperandExtendedAdd) <=> |
| 2036 | // (SAdd == OperandExtendedAdd => AR is NW) |
| 2037 | |
| 2038 | setNoWrapFlags(const_cast<SCEVAddRecExpr *>(AR), SCEV::FlagNW); |
| 2039 | |
| 2040 | // Return the expression with the addrec on the outside. |
| 2041 | return getAddRecExpr( |
| 2042 | getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, |
| 2043 | Depth + 1), |
| 2044 | getZeroExtendExpr(Step, Ty, Depth + 1), L, |
| 2045 | AR->getNoWrapFlags()); |
| 2046 | } |
| 2047 | } |
| 2048 | } |
| 2049 | |
| 2050 | auto NewFlags = proveNoSignedWrapViaInduction(AR); |
| 2051 | setNoWrapFlags(const_cast<SCEVAddRecExpr *>(AR), NewFlags); |
| 2052 | if (AR->hasNoSignedWrap()) { |
| 2053 | // Same as nsw case above - duplicated here to avoid a compile time |
| 2054 | // issue. It's not clear that the order of checks does matter, but |
| 2055 | // it's one of two issue possible causes for a change which was |
| 2056 | // reverted. Be conservative for the moment. |
| 2057 | return getAddRecExpr( |
| 2058 | getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, Depth + 1), |
| 2059 | getSignExtendExpr(Step, Ty, Depth + 1), L, AR->getNoWrapFlags()); |
| 2060 | } |
| 2061 | |
| 2062 | // sext({C,+,Step}) --> (sext(D) + sext({C-D,+,Step}))<nuw><nsw> |
| 2063 | // if D + (C - D + Step * n) could be proven to not signed wrap |
| 2064 | // where D maximizes the number of trailing zeros of (C - D + Step * n) |
| 2065 | if (const auto *SC = dyn_cast<SCEVConstant>(Start)) { |
| 2066 | const APInt &C = SC->getAPInt(); |
| 2067 | const APInt &D = extractConstantWithoutWrapping(*this, C, Step); |
| 2068 | if (D != 0) { |
| 2069 | const SCEV *SSExtD = getSignExtendExpr(getConstant(D), Ty, Depth); |
| 2070 | const SCEV *SResidual = |
| 2071 | getAddRecExpr(getConstant(C - D), Step, L, AR->getNoWrapFlags()); |
| 2072 | const SCEV *SSExtR = getSignExtendExpr(SResidual, Ty, Depth + 1); |
| 2073 | return getAddExpr(SSExtD, SSExtR, |
| 2074 | (SCEV::NoWrapFlags)(SCEV::FlagNSW | SCEV::FlagNUW), |
| 2075 | Depth + 1); |
| 2076 | } |
| 2077 | } |
| 2078 | |
| 2079 | if (proveNoWrapByVaryingStart<SCEVSignExtendExpr>(Start, Step, L)) { |
| 2080 | setNoWrapFlags(const_cast<SCEVAddRecExpr *>(AR), SCEV::FlagNSW); |
| 2081 | return getAddRecExpr( |
| 2082 | getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, Depth + 1), |
| 2083 | getSignExtendExpr(Step, Ty, Depth + 1), L, AR->getNoWrapFlags()); |
| 2084 | } |
| 2085 | } |
| 2086 | |
| 2087 | // If the input value is provably positive and we could not simplify |
| 2088 | // away the sext build a zext instead. |
| 2089 | if (isKnownNonNegative(Op)) |
| 2090 | return getZeroExtendExpr(Op, Ty, Depth + 1); |
| 2091 | |
| 2092 | // The cast wasn't folded; create an explicit cast node. |
| 2093 | // Recompute the insert position, as it may have been invalidated. |
| 2094 | if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S; |
| 2095 | SCEV *S = new (SCEVAllocator) SCEVSignExtendExpr(ID.Intern(SCEVAllocator), |
| 2096 | Op, Ty); |
| 2097 | UniqueSCEVs.InsertNode(S, IP); |
| 2098 | addToLoopUseLists(S); |
| 2099 | return S; |
| 2100 | } |
| 2101 | |
| 2102 | /// getAnyExtendExpr - Return a SCEV for the given operand extended with |
| 2103 | /// unspecified bits out to the given type. |
| 2104 | const SCEV *ScalarEvolution::getAnyExtendExpr(const SCEV *Op, |
| 2105 | Type *Ty) { |
| 2106 | assert(getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) &&(static_cast <bool> (getTypeSizeInBits(Op->getType() ) < getTypeSizeInBits(Ty) && "This is not an extending conversion!" ) ? void (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 2107, __extension__ __PRETTY_FUNCTION__)) |
| 2107 | "This is not an extending conversion!")(static_cast <bool> (getTypeSizeInBits(Op->getType() ) < getTypeSizeInBits(Ty) && "This is not an extending conversion!" ) ? void (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 2107, __extension__ __PRETTY_FUNCTION__)); |
| 2108 | assert(isSCEVable(Ty) &&(static_cast <bool> (isSCEVable(Ty) && "This is not a conversion to a SCEVable type!" ) ? void (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 2109, __extension__ __PRETTY_FUNCTION__)) |
| 2109 | "This is not a conversion to a SCEVable type!")(static_cast <bool> (isSCEVable(Ty) && "This is not a conversion to a SCEVable type!" ) ? void (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 2109, __extension__ __PRETTY_FUNCTION__)); |
| 2110 | Ty = getEffectiveSCEVType(Ty); |
| 2111 | |
| 2112 | // Sign-extend negative constants. |
| 2113 | if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op)) |
| 2114 | if (SC->getAPInt().isNegative()) |
| 2115 | return getSignExtendExpr(Op, Ty); |
| 2116 | |
| 2117 | // Peel off a truncate cast. |
| 2118 | if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(Op)) { |
| 2119 | const SCEV *NewOp = T->getOperand(); |
| 2120 | if (getTypeSizeInBits(NewOp->getType()) < getTypeSizeInBits(Ty)) |
| 2121 | return getAnyExtendExpr(NewOp, Ty); |
| 2122 | return getTruncateOrNoop(NewOp, Ty); |
| 2123 | } |
| 2124 | |
| 2125 | // Next try a zext cast. If the cast is folded, use it. |
| 2126 | const SCEV *ZExt = getZeroExtendExpr(Op, Ty); |
| 2127 | if (!isa<SCEVZeroExtendExpr>(ZExt)) |
| 2128 | return ZExt; |
| 2129 | |
| 2130 | // Next try a sext cast. If the cast is folded, use it. |
| 2131 | const SCEV *SExt = getSignExtendExpr(Op, Ty); |
| 2132 | if (!isa<SCEVSignExtendExpr>(SExt)) |
| 2133 | return SExt; |
| 2134 | |
| 2135 | // Force the cast to be folded into the operands of an addrec. |
| 2136 | if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op)) { |
| 2137 | SmallVector<const SCEV *, 4> Ops; |
| 2138 | for (const SCEV *Op : AR->operands()) |
| 2139 | Ops.push_back(getAnyExtendExpr(Op, Ty)); |
| 2140 | return getAddRecExpr(Ops, AR->getLoop(), SCEV::FlagNW); |
| 2141 | } |
| 2142 | |
| 2143 | // If the expression is obviously signed, use the sext cast value. |
| 2144 | if (isa<SCEVSMaxExpr>(Op)) |
| 2145 | return SExt; |
| 2146 | |
| 2147 | // Absent any other information, use the zext cast value. |
| 2148 | return ZExt; |
| 2149 | } |
| 2150 | |
| 2151 | /// Process the given Ops list, which is a list of operands to be added under |
| 2152 | /// the given scale, update the given map. This is a helper function for |
| 2153 | /// getAddRecExpr. As an example of what it does, given a sequence of operands |
| 2154 | /// that would form an add expression like this: |
| 2155 | /// |
| 2156 | /// m + n + 13 + (A * (o + p + (B * (q + m + 29)))) + r + (-1 * r) |
| 2157 | /// |
| 2158 | /// where A and B are constants, update the map with these values: |
| 2159 | /// |
| 2160 | /// (m, 1+A*B), (n, 1), (o, A), (p, A), (q, A*B), (r, 0) |
| 2161 | /// |
| 2162 | /// and add 13 + A*B*29 to AccumulatedConstant. |
| 2163 | /// This will allow getAddRecExpr to produce this: |
| 2164 | /// |
| 2165 | /// 13+A*B*29 + n + (m * (1+A*B)) + ((o + p) * A) + (q * A*B) |
| 2166 | /// |
| 2167 | /// This form often exposes folding opportunities that are hidden in |
| 2168 | /// the original operand list. |
| 2169 | /// |
| 2170 | /// Return true iff it appears that any interesting folding opportunities |
| 2171 | /// may be exposed. This helps getAddRecExpr short-circuit extra work in |
| 2172 | /// the common case where no interesting opportunities are present, and |
| 2173 | /// is also used as a check to avoid infinite recursion. |
| 2174 | static bool |
| 2175 | CollectAddOperandsWithScales(DenseMap<const SCEV *, APInt> &M, |
| 2176 | SmallVectorImpl<const SCEV *> &NewOps, |
| 2177 | APInt &AccumulatedConstant, |
| 2178 | const SCEV *const *Ops, size_t NumOperands, |
| 2179 | const APInt &Scale, |
| 2180 | ScalarEvolution &SE) { |
| 2181 | bool Interesting = false; |
| 2182 | |
| 2183 | // Iterate over the add operands. They are sorted, with constants first. |
| 2184 | unsigned i = 0; |
| 2185 | while (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[i])) { |
| 2186 | ++i; |
| 2187 | // Pull a buried constant out to the outside. |
| 2188 | if (Scale != 1 || AccumulatedConstant != 0 || C->getValue()->isZero()) |
| 2189 | Interesting = true; |
| 2190 | AccumulatedConstant += Scale * C->getAPInt(); |
| 2191 | } |
| 2192 | |
| 2193 | // Next comes everything else. We're especially interested in multiplies |
| 2194 | // here, but they're in the middle, so just visit the rest with one loop. |
| 2195 | for (; i != NumOperands; ++i) { |
| 2196 | const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(Ops[i]); |
| 2197 | if (Mul && isa<SCEVConstant>(Mul->getOperand(0))) { |
| 2198 | APInt NewScale = |
| 2199 | Scale * cast<SCEVConstant>(Mul->getOperand(0))->getAPInt(); |
| 2200 | if (Mul->getNumOperands() == 2 && isa<SCEVAddExpr>(Mul->getOperand(1))) { |
| 2201 | // A multiplication of a constant with another add; recurse. |
| 2202 | const SCEVAddExpr *Add = cast<SCEVAddExpr>(Mul->getOperand(1)); |
| 2203 | Interesting |= |
| 2204 | CollectAddOperandsWithScales(M, NewOps, AccumulatedConstant, |
| 2205 | Add->op_begin(), Add->getNumOperands(), |
| 2206 | NewScale, SE); |
| 2207 | } else { |
| 2208 | // A multiplication of a constant with some other value. Update |
| 2209 | // the map. |
| 2210 | SmallVector<const SCEV *, 4> MulOps(drop_begin(Mul->operands())); |
| 2211 | const SCEV *Key = SE.getMulExpr(MulOps); |
| 2212 | auto Pair = M.insert({Key, NewScale}); |
| 2213 | if (Pair.second) { |
| 2214 | NewOps.push_back(Pair.first->first); |
| 2215 | } else { |
| 2216 | Pair.first->second += NewScale; |
| 2217 | // The map already had an entry for this value, which may indicate |
| 2218 | // a folding opportunity. |
| 2219 | Interesting = true; |
| 2220 | } |
| 2221 | } |
| 2222 | } else { |
| 2223 | // An ordinary operand. Update the map. |
| 2224 | std::pair<DenseMap<const SCEV *, APInt>::iterator, bool> Pair = |
| 2225 | M.insert({Ops[i], Scale}); |
| 2226 | if (Pair.second) { |
| 2227 | NewOps.push_back(Pair.first->first); |
| 2228 | } else { |
| 2229 | Pair.first->second += Scale; |
| 2230 | // The map already had an entry for this value, which may indicate |
| 2231 | // a folding opportunity. |
| 2232 | Interesting = true; |
| 2233 | } |
| 2234 | } |
| 2235 | } |
| 2236 | |
| 2237 | return Interesting; |
| 2238 | } |
| 2239 | |
| 2240 | // We're trying to construct a SCEV of type `Type' with `Ops' as operands and |
| 2241 | // `OldFlags' as can't-wrap behavior. Infer a more aggressive set of |
| 2242 | // can't-overflow flags for the operation if possible. |
| 2243 | static SCEV::NoWrapFlags |
| 2244 | StrengthenNoWrapFlags(ScalarEvolution *SE, SCEVTypes Type, |
| 2245 | const ArrayRef<const SCEV *> Ops, |
| 2246 | SCEV::NoWrapFlags Flags) { |
| 2247 | using namespace std::placeholders; |
| 2248 | |
| 2249 | using OBO = OverflowingBinaryOperator; |
| 2250 | |
| 2251 | bool CanAnalyze = |
| 2252 | Type == scAddExpr || Type == scAddRecExpr || Type == scMulExpr; |
| 2253 | (void)CanAnalyze; |
| 2254 | assert(CanAnalyze && "don't call from other places!")(static_cast <bool> (CanAnalyze && "don't call from other places!" ) ? void (0) : __assert_fail ("CanAnalyze && \"don't call from other places!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 2254, __extension__ __PRETTY_FUNCTION__)); |
| 2255 | |
| 2256 | int SignOrUnsignMask = SCEV::FlagNUW | SCEV::FlagNSW; |
| 2257 | SCEV::NoWrapFlags SignOrUnsignWrap = |
| 2258 | ScalarEvolution::maskFlags(Flags, SignOrUnsignMask); |
| 2259 | |
| 2260 | // If FlagNSW is true and all the operands are non-negative, infer FlagNUW. |
| 2261 | auto IsKnownNonNegative = [&](const SCEV *S) { |
| 2262 | return SE->isKnownNonNegative(S); |
| 2263 | }; |
| 2264 | |
| 2265 | if (SignOrUnsignWrap == SCEV::FlagNSW && all_of(Ops, IsKnownNonNegative)) |
| 2266 | Flags = |
| 2267 | ScalarEvolution::setFlags(Flags, (SCEV::NoWrapFlags)SignOrUnsignMask); |
| 2268 | |
| 2269 | SignOrUnsignWrap = ScalarEvolution::maskFlags(Flags, SignOrUnsignMask); |
| 2270 | |
| 2271 | if (SignOrUnsignWrap != SignOrUnsignMask && |
| 2272 | (Type == scAddExpr || Type == scMulExpr) && Ops.size() == 2 && |
| 2273 | isa<SCEVConstant>(Ops[0])) { |
| 2274 | |
| 2275 | auto Opcode = [&] { |
| 2276 | switch (Type) { |
| 2277 | case scAddExpr: |
| 2278 | return Instruction::Add; |
| 2279 | case scMulExpr: |
| 2280 | return Instruction::Mul; |
| 2281 | default: |
| 2282 | llvm_unreachable("Unexpected SCEV op.")::llvm::llvm_unreachable_internal("Unexpected SCEV op.", "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 2282); |
| 2283 | } |
| 2284 | }(); |
| 2285 | |
| 2286 | const APInt &C = cast<SCEVConstant>(Ops[0])->getAPInt(); |
| 2287 | |
| 2288 | // (A <opcode> C) --> (A <opcode> C)<nsw> if the op doesn't sign overflow. |
| 2289 | if (!(SignOrUnsignWrap & SCEV::FlagNSW)) { |
| 2290 | auto NSWRegion = ConstantRange::makeGuaranteedNoWrapRegion( |
| 2291 | Opcode, C, OBO::NoSignedWrap); |
| 2292 | if (NSWRegion.contains(SE->getSignedRange(Ops[1]))) |
| 2293 | Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNSW); |
| 2294 | } |
| 2295 | |
| 2296 | // (A <opcode> C) --> (A <opcode> C)<nuw> if the op doesn't unsign overflow. |
| 2297 | if (!(SignOrUnsignWrap & SCEV::FlagNUW)) { |
| 2298 | auto NUWRegion = ConstantRange::makeGuaranteedNoWrapRegion( |
| 2299 | Opcode, C, OBO::NoUnsignedWrap); |
| 2300 | if (NUWRegion.contains(SE->getUnsignedRange(Ops[1]))) |
| 2301 | Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNUW); |
| 2302 | } |
| 2303 | } |
| 2304 | |
| 2305 | return Flags; |
| 2306 | } |
| 2307 | |
| 2308 | bool ScalarEvolution::isAvailableAtLoopEntry(const SCEV *S, const Loop *L) { |
| 2309 | return isLoopInvariant(S, L) && properlyDominates(S, L->getHeader()); |
| 2310 | } |
| 2311 | |
| 2312 | /// Get a canonical add expression, or something simpler if possible. |
| 2313 | const SCEV *ScalarEvolution::getAddExpr(SmallVectorImpl<const SCEV *> &Ops, |
| 2314 | SCEV::NoWrapFlags OrigFlags, |
| 2315 | unsigned Depth) { |
| 2316 | assert(!(OrigFlags & ~(SCEV::FlagNUW | SCEV::FlagNSW)) &&(static_cast <bool> (!(OrigFlags & ~(SCEV::FlagNUW | SCEV::FlagNSW)) && "only nuw or nsw allowed") ? void (0) : __assert_fail ("!(OrigFlags & ~(SCEV::FlagNUW | SCEV::FlagNSW)) && \"only nuw or nsw allowed\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 2317, __extension__ __PRETTY_FUNCTION__)) |
| 2317 | "only nuw or nsw allowed")(static_cast <bool> (!(OrigFlags & ~(SCEV::FlagNUW | SCEV::FlagNSW)) && "only nuw or nsw allowed") ? void (0) : __assert_fail ("!(OrigFlags & ~(SCEV::FlagNUW | SCEV::FlagNSW)) && \"only nuw or nsw allowed\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 2317, __extension__ __PRETTY_FUNCTION__)); |
| 2318 | assert(!Ops.empty() && "Cannot get empty add!")(static_cast <bool> (!Ops.empty() && "Cannot get empty add!" ) ? void (0) : __assert_fail ("!Ops.empty() && \"Cannot get empty add!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 2318, __extension__ __PRETTY_FUNCTION__)); |
| 2319 | if (Ops.size() == 1) return Ops[0]; |
| 2320 | #ifndef NDEBUG |
| 2321 | Type *ETy = getEffectiveSCEVType(Ops[0]->getType()); |
| 2322 | for (unsigned i = 1, e = Ops.size(); i != e; ++i) |
| 2323 | assert(getEffectiveSCEVType(Ops[i]->getType()) == ETy &&(static_cast <bool> (getEffectiveSCEVType(Ops[i]->getType ()) == ETy && "SCEVAddExpr operand types don't match!" ) ? void (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVAddExpr operand types don't match!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 2324, __extension__ __PRETTY_FUNCTION__)) |
| 2324 | "SCEVAddExpr operand types don't match!")(static_cast <bool> (getEffectiveSCEVType(Ops[i]->getType ()) == ETy && "SCEVAddExpr operand types don't match!" ) ? void (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVAddExpr operand types don't match!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 2324, __extension__ __PRETTY_FUNCTION__)); |
| 2325 | #endif |
| 2326 | |
| 2327 | // Sort by complexity, this groups all similar expression types together. |
| 2328 | GroupByComplexity(Ops, &LI, DT); |
| 2329 | |
| 2330 | // If there are any constants, fold them together. |
| 2331 | unsigned Idx = 0; |
| 2332 | if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) { |
| 2333 | ++Idx; |
| 2334 | assert(Idx < Ops.size())(static_cast <bool> (Idx < Ops.size()) ? void (0) : __assert_fail ("Idx < Ops.size()", "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 2334, __extension__ __PRETTY_FUNCTION__)); |
| 2335 | while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) { |
| 2336 | // We found two constants, fold them together! |
| 2337 | Ops[0] = getConstant(LHSC->getAPInt() + RHSC->getAPInt()); |
| 2338 | if (Ops.size() == 2) return Ops[0]; |
| 2339 | Ops.erase(Ops.begin()+1); // Erase the folded element |
| 2340 | LHSC = cast<SCEVConstant>(Ops[0]); |
| 2341 | } |
| 2342 | |
| 2343 | // If we are left with a constant zero being added, strip it off. |
| 2344 | if (LHSC->getValue()->isZero()) { |
| 2345 | Ops.erase(Ops.begin()); |
| 2346 | --Idx; |
| 2347 | } |
| 2348 | |
| 2349 | if (Ops.size() == 1) return Ops[0]; |
| 2350 | } |
| 2351 | |
| 2352 | // Delay expensive flag strengthening until necessary. |
| 2353 | auto ComputeFlags = [this, OrigFlags](const ArrayRef<const SCEV *> Ops) { |
| 2354 | return StrengthenNoWrapFlags(this, scAddExpr, Ops, OrigFlags); |
| 2355 | }; |
| 2356 | |
| 2357 | // Limit recursion calls depth. |
| 2358 | if (Depth > MaxArithDepth || hasHugeExpression(Ops)) |
| 2359 | return getOrCreateAddExpr(Ops, ComputeFlags(Ops)); |
| 2360 | |
| 2361 | if (SCEV *S = std::get<0>(findExistingSCEVInCache(scAddExpr, Ops))) { |
| 2362 | // Don't strengthen flags if we have no new information. |
| 2363 | SCEVAddExpr *Add = static_cast<SCEVAddExpr *>(S); |
| 2364 | if (Add->getNoWrapFlags(OrigFlags) != OrigFlags) |
| 2365 | Add->setNoWrapFlags(ComputeFlags(Ops)); |
| 2366 | return S; |
| 2367 | } |
| 2368 | |
| 2369 | // Okay, check to see if the same value occurs in the operand list more than |
| 2370 | // once. If so, merge them together into an multiply expression. Since we |
| 2371 | // sorted the list, these values are required to be adjacent. |
| 2372 | Type *Ty = Ops[0]->getType(); |
| 2373 | bool FoundMatch = false; |
| 2374 | for (unsigned i = 0, e = Ops.size(); i != e-1; ++i) |
| 2375 | if (Ops[i] == Ops[i+1]) { // X + Y + Y --> X + Y*2 |
| 2376 | // Scan ahead to count how many equal operands there are. |
| 2377 | unsigned Count = 2; |
| 2378 | while (i+Count != e && Ops[i+Count] == Ops[i]) |
| 2379 | ++Count; |
| 2380 | // Merge the values into a multiply. |
| 2381 | const SCEV *Scale = getConstant(Ty, Count); |
| 2382 | const SCEV *Mul = getMulExpr(Scale, Ops[i], SCEV::FlagAnyWrap, Depth + 1); |
| 2383 | if (Ops.size() == Count) |
| 2384 | return Mul; |
| 2385 | Ops[i] = Mul; |
| 2386 | Ops.erase(Ops.begin()+i+1, Ops.begin()+i+Count); |
| 2387 | --i; e -= Count - 1; |
| 2388 | FoundMatch = true; |
| 2389 | } |
| 2390 | if (FoundMatch) |
| 2391 | return getAddExpr(Ops, OrigFlags, Depth + 1); |
| 2392 | |
| 2393 | // Check for truncates. If all the operands are truncated from the same |
| 2394 | // type, see if factoring out the truncate would permit the result to be |
| 2395 | // folded. eg., n*trunc(x) + m*trunc(y) --> trunc(trunc(m)*x + trunc(n)*y) |
| 2396 | // if the contents of the resulting outer trunc fold to something simple. |
| 2397 | auto FindTruncSrcType = [&]() -> Type * { |
| 2398 | // We're ultimately looking to fold an addrec of truncs and muls of only |
| 2399 | // constants and truncs, so if we find any other types of SCEV |
| 2400 | // as operands of the addrec then we bail and return nullptr here. |
| 2401 | // Otherwise, we return the type of the operand of a trunc that we find. |
| 2402 | if (auto *T = dyn_cast<SCEVTruncateExpr>(Ops[Idx])) |
| 2403 | return T->getOperand()->getType(); |
| 2404 | if (const auto *Mul = dyn_cast<SCEVMulExpr>(Ops[Idx])) { |
| 2405 | const auto *LastOp = Mul->getOperand(Mul->getNumOperands() - 1); |
| 2406 | if (const auto *T = dyn_cast<SCEVTruncateExpr>(LastOp)) |
| 2407 | return T->getOperand()->getType(); |
| 2408 | } |
| 2409 | return nullptr; |
| 2410 | }; |
| 2411 | if (auto *SrcType = FindTruncSrcType()) { |
| 2412 | SmallVector<const SCEV *, 8> LargeOps; |
| 2413 | bool Ok = true; |
| 2414 | // Check all the operands to see if they can be represented in the |
| 2415 | // source type of the truncate. |
| 2416 | for (unsigned i = 0, e = Ops.size(); i != e; ++i) { |
| 2417 | if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(Ops[i])) { |
| 2418 | if (T->getOperand()->getType() != SrcType) { |
| 2419 | Ok = false; |
| 2420 | break; |
| 2421 | } |
| 2422 | LargeOps.push_back(T->getOperand()); |
| 2423 | } else if (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[i])) { |
| 2424 | LargeOps.push_back(getAnyExtendExpr(C, SrcType)); |
| 2425 | } else if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(Ops[i])) { |
| 2426 | SmallVector<const SCEV *, 8> LargeMulOps; |
| 2427 | for (unsigned j = 0, f = M->getNumOperands(); j != f && Ok; ++j) { |
| 2428 | if (const SCEVTruncateExpr *T = |
| 2429 | dyn_cast<SCEVTruncateExpr>(M->getOperand(j))) { |
| 2430 | if (T->getOperand()->getType() != SrcType) { |
| 2431 | Ok = false; |
| 2432 | break; |
| 2433 | } |
| 2434 | LargeMulOps.push_back(T->getOperand()); |
| 2435 | } else if (const auto *C = dyn_cast<SCEVConstant>(M->getOperand(j))) { |
| 2436 | LargeMulOps.push_back(getAnyExtendExpr(C, SrcType)); |
| 2437 | } else { |
| 2438 | Ok = false; |
| 2439 | break; |
| 2440 | } |
| 2441 | } |
| 2442 | if (Ok) |
| 2443 | LargeOps.push_back(getMulExpr(LargeMulOps, SCEV::FlagAnyWrap, Depth + 1)); |
| 2444 | } else { |
| 2445 | Ok = false; |
| 2446 | break; |
| 2447 | } |
| 2448 | } |
| 2449 | if (Ok) { |
| 2450 | // Evaluate the expression in the larger type. |
| 2451 | const SCEV *Fold = getAddExpr(LargeOps, SCEV::FlagAnyWrap, Depth + 1); |
| 2452 | // If it folds to something simple, use it. Otherwise, don't. |
| 2453 | if (isa<SCEVConstant>(Fold) || isa<SCEVUnknown>(Fold)) |
| 2454 | return getTruncateExpr(Fold, Ty); |
| 2455 | } |
| 2456 | } |
| 2457 | |
| 2458 | // Skip past any other cast SCEVs. |
| 2459 | while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddExpr) |
| 2460 | ++Idx; |
| 2461 | |
| 2462 | // If there are add operands they would be next. |
| 2463 | if (Idx < Ops.size()) { |
| 2464 | bool DeletedAdd = false; |
| 2465 | while (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[Idx])) { |
| 2466 | if (Ops.size() > AddOpsInlineThreshold || |
| 2467 | Add->getNumOperands() > AddOpsInlineThreshold) |
| 2468 | break; |
| 2469 | // If we have an add, expand the add operands onto the end of the operands |
| 2470 | // list. |
| 2471 | Ops.erase(Ops.begin()+Idx); |
| 2472 | Ops.append(Add->op_begin(), Add->op_end()); |
| 2473 | DeletedAdd = true; |
| 2474 | } |
| 2475 | |
| 2476 | // If we deleted at least one add, we added operands to the end of the list, |
| 2477 | // and they are not necessarily sorted. Recurse to resort and resimplify |
| 2478 | // any operands we just acquired. |
| 2479 | if (DeletedAdd) |
| 2480 | return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1); |
| 2481 | } |
| 2482 | |
| 2483 | // Skip over the add expression until we get to a multiply. |
| 2484 | while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scMulExpr) |
| 2485 | ++Idx; |
| 2486 | |
| 2487 | // Check to see if there are any folding opportunities present with |
| 2488 | // operands multiplied by constant values. |
| 2489 | if (Idx < Ops.size() && isa<SCEVMulExpr>(Ops[Idx])) { |
| 2490 | uint64_t BitWidth = getTypeSizeInBits(Ty); |
| 2491 | DenseMap<const SCEV *, APInt> M; |
| 2492 | SmallVector<const SCEV *, 8> NewOps; |
| 2493 | APInt AccumulatedConstant(BitWidth, 0); |
| 2494 | if (CollectAddOperandsWithScales(M, NewOps, AccumulatedConstant, |
| 2495 | Ops.data(), Ops.size(), |
| 2496 | APInt(BitWidth, 1), *this)) { |
| 2497 | struct APIntCompare { |
| 2498 | bool operator()(const APInt &LHS, const APInt &RHS) const { |
| 2499 | return LHS.ult(RHS); |
| 2500 | } |
| 2501 | }; |
| 2502 | |
| 2503 | // Some interesting folding opportunity is present, so its worthwhile to |
| 2504 | // re-generate the operands list. Group the operands by constant scale, |
| 2505 | // to avoid multiplying by the same constant scale multiple times. |
| 2506 | std::map<APInt, SmallVector<const SCEV *, 4>, APIntCompare> MulOpLists; |
| 2507 | for (const SCEV *NewOp : NewOps) |
| 2508 | MulOpLists[M.find(NewOp)->second].push_back(NewOp); |
| 2509 | // Re-generate the operands list. |
| 2510 | Ops.clear(); |
| 2511 | if (AccumulatedConstant != 0) |
| 2512 | Ops.push_back(getConstant(AccumulatedConstant)); |
| 2513 | for (auto &MulOp : MulOpLists) |
| 2514 | if (MulOp.first != 0) |
| 2515 | Ops.push_back(getMulExpr( |
| 2516 | getConstant(MulOp.first), |
| 2517 | getAddExpr(MulOp.second, SCEV::FlagAnyWrap, Depth + 1), |
| 2518 | SCEV::FlagAnyWrap, Depth + 1)); |
| 2519 | if (Ops.empty()) |
| 2520 | return getZero(Ty); |
| 2521 | if (Ops.size() == 1) |
| 2522 | return Ops[0]; |
| 2523 | return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1); |
| 2524 | } |
| 2525 | } |
| 2526 | |
| 2527 | // If we are adding something to a multiply expression, make sure the |
| 2528 | // something is not already an operand of the multiply. If so, merge it into |
| 2529 | // the multiply. |
| 2530 | for (; Idx < Ops.size() && isa<SCEVMulExpr>(Ops[Idx]); ++Idx) { |
| 2531 | const SCEVMulExpr *Mul = cast<SCEVMulExpr>(Ops[Idx]); |
| 2532 | for (unsigned MulOp = 0, e = Mul->getNumOperands(); MulOp != e; ++MulOp) { |
| 2533 | const SCEV *MulOpSCEV = Mul->getOperand(MulOp); |
| 2534 | if (isa<SCEVConstant>(MulOpSCEV)) |
| 2535 | continue; |
| 2536 | for (unsigned AddOp = 0, e = Ops.size(); AddOp != e; ++AddOp) |
| 2537 | if (MulOpSCEV == Ops[AddOp]) { |
| 2538 | // Fold W + X + (X * Y * Z) --> W + (X * ((Y*Z)+1)) |
| 2539 | const SCEV *InnerMul = Mul->getOperand(MulOp == 0); |
| 2540 | if (Mul->getNumOperands() != 2) { |
| 2541 | // If the multiply has more than two operands, we must get the |
| 2542 | // Y*Z term. |
| 2543 | SmallVector<const SCEV *, 4> MulOps(Mul->op_begin(), |
| 2544 | Mul->op_begin()+MulOp); |
| 2545 | MulOps.append(Mul->op_begin()+MulOp+1, Mul->op_end()); |
| 2546 | InnerMul = getMulExpr(MulOps, SCEV::FlagAnyWrap, Depth + 1); |
| 2547 | } |
| 2548 | SmallVector<const SCEV *, 2> TwoOps = {getOne(Ty), InnerMul}; |
| 2549 | const SCEV *AddOne = getAddExpr(TwoOps, SCEV::FlagAnyWrap, Depth + 1); |
| 2550 | const SCEV *OuterMul = getMulExpr(AddOne, MulOpSCEV, |
| 2551 | SCEV::FlagAnyWrap, Depth + 1); |
| 2552 | if (Ops.size() == 2) return OuterMul; |
| 2553 | if (AddOp < Idx) { |
| 2554 | Ops.erase(Ops.begin()+AddOp); |
| 2555 | Ops.erase(Ops.begin()+Idx-1); |
| 2556 | } else { |
| 2557 | Ops.erase(Ops.begin()+Idx); |
| 2558 | Ops.erase(Ops.begin()+AddOp-1); |
| 2559 | } |
| 2560 | Ops.push_back(OuterMul); |
| 2561 | return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1); |
| 2562 | } |
| 2563 | |
| 2564 | // Check this multiply against other multiplies being added together. |
| 2565 | for (unsigned OtherMulIdx = Idx+1; |
| 2566 | OtherMulIdx < Ops.size() && isa<SCEVMulExpr>(Ops[OtherMulIdx]); |
| 2567 | ++OtherMulIdx) { |
| 2568 | const SCEVMulExpr *OtherMul = cast<SCEVMulExpr>(Ops[OtherMulIdx]); |
| 2569 | // If MulOp occurs in OtherMul, we can fold the two multiplies |
| 2570 | // together. |
| 2571 | for (unsigned OMulOp = 0, e = OtherMul->getNumOperands(); |
| 2572 | OMulOp != e; ++OMulOp) |
| 2573 | if (OtherMul->getOperand(OMulOp) == MulOpSCEV) { |
| 2574 | // Fold X + (A*B*C) + (A*D*E) --> X + (A*(B*C+D*E)) |
| 2575 | const SCEV *InnerMul1 = Mul->getOperand(MulOp == 0); |
| 2576 | if (Mul->getNumOperands() != 2) { |
| 2577 | SmallVector<const SCEV *, 4> MulOps(Mul->op_begin(), |
| 2578 | Mul->op_begin()+MulOp); |
| 2579 | MulOps.append(Mul->op_begin()+MulOp+1, Mul->op_end()); |
| 2580 | InnerMul1 = getMulExpr(MulOps, SCEV::FlagAnyWrap, Depth + 1); |
| 2581 | } |
| 2582 | const SCEV *InnerMul2 = OtherMul->getOperand(OMulOp == 0); |
| 2583 | if (OtherMul->getNumOperands() != 2) { |
| 2584 | SmallVector<const SCEV *, 4> MulOps(OtherMul->op_begin(), |
| 2585 | OtherMul->op_begin()+OMulOp); |
| 2586 | MulOps.append(OtherMul->op_begin()+OMulOp+1, OtherMul->op_end()); |
| 2587 | InnerMul2 = getMulExpr(MulOps, SCEV::FlagAnyWrap, Depth + 1); |
| 2588 | } |
| 2589 | SmallVector<const SCEV *, 2> TwoOps = {InnerMul1, InnerMul2}; |
| 2590 | const SCEV *InnerMulSum = |
| 2591 | getAddExpr(TwoOps, SCEV::FlagAnyWrap, Depth + 1); |
| 2592 | const SCEV *OuterMul = getMulExpr(MulOpSCEV, InnerMulSum, |
| 2593 | SCEV::FlagAnyWrap, Depth + 1); |
| 2594 | if (Ops.size() == 2) return OuterMul; |
| 2595 | Ops.erase(Ops.begin()+Idx); |
| 2596 | Ops.erase(Ops.begin()+OtherMulIdx-1); |
| 2597 | Ops.push_back(OuterMul); |
| 2598 | return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1); |
| 2599 | } |
| 2600 | } |
| 2601 | } |
| 2602 | } |
| 2603 | |
| 2604 | // If there are any add recurrences in the operands list, see if any other |
| 2605 | // added values are loop invariant. If so, we can fold them into the |
| 2606 | // recurrence. |
| 2607 | while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddRecExpr) |
| 2608 | ++Idx; |
| 2609 | |
| 2610 | // Scan over all recurrences, trying to fold loop invariants into them. |
| 2611 | for (; Idx < Ops.size() && isa<SCEVAddRecExpr>(Ops[Idx]); ++Idx) { |
| 2612 | // Scan all of the other operands to this add and add them to the vector if |
| 2613 | // they are loop invariant w.r.t. the recurrence. |
| 2614 | SmallVector<const SCEV *, 8> LIOps; |
| 2615 | const SCEVAddRecExpr *AddRec = cast<SCEVAddRecExpr>(Ops[Idx]); |
| 2616 | const Loop *AddRecLoop = AddRec->getLoop(); |
| 2617 | for (unsigned i = 0, e = Ops.size(); i != e; ++i) |
| 2618 | if (isAvailableAtLoopEntry(Ops[i], AddRecLoop)) { |
| 2619 | LIOps.push_back(Ops[i]); |
| 2620 | Ops.erase(Ops.begin()+i); |
| 2621 | --i; --e; |
| 2622 | } |
| 2623 | |
| 2624 | // If we found some loop invariants, fold them into the recurrence. |
| 2625 | if (!LIOps.empty()) { |
| 2626 | // Compute nowrap flags for the addition of the loop-invariant ops and |
| 2627 | // the addrec. Temporarily push it as an operand for that purpose. |
| 2628 | LIOps.push_back(AddRec); |
| 2629 | SCEV::NoWrapFlags Flags = ComputeFlags(LIOps); |
| 2630 | LIOps.pop_back(); |
| 2631 | |
| 2632 | // NLI + LI + {Start,+,Step} --> NLI + {LI+Start,+,Step} |
| 2633 | LIOps.push_back(AddRec->getStart()); |
| 2634 | |
| 2635 | SmallVector<const SCEV *, 4> AddRecOps(AddRec->operands()); |
| 2636 | // This follows from the fact that the no-wrap flags on the outer add |
| 2637 | // expression are applicable on the 0th iteration, when the add recurrence |
| 2638 | // will be equal to its start value. |
| 2639 | AddRecOps[0] = getAddExpr(LIOps, Flags, Depth + 1); |
| 2640 | |
| 2641 | // Build the new addrec. Propagate the NUW and NSW flags if both the |
| 2642 | // outer add and the inner addrec are guaranteed to have no overflow. |
| 2643 | // Always propagate NW. |
| 2644 | Flags = AddRec->getNoWrapFlags(setFlags(Flags, SCEV::FlagNW)); |
| 2645 | const SCEV *NewRec = getAddRecExpr(AddRecOps, AddRecLoop, Flags); |
| 2646 | |
| 2647 | // If all of the other operands were loop invariant, we are done. |
| 2648 | if (Ops.size() == 1) return NewRec; |
| 2649 | |
| 2650 | // Otherwise, add the folded AddRec by the non-invariant parts. |
| 2651 | for (unsigned i = 0;; ++i) |
| 2652 | if (Ops[i] == AddRec) { |
| 2653 | Ops[i] = NewRec; |
| 2654 | break; |
| 2655 | } |
| 2656 | return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1); |
| 2657 | } |
| 2658 | |
| 2659 | // Okay, if there weren't any loop invariants to be folded, check to see if |
| 2660 | // there are multiple AddRec's with the same loop induction variable being |
| 2661 | // added together. If so, we can fold them. |
| 2662 | for (unsigned OtherIdx = Idx+1; |
| 2663 | OtherIdx < Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]); |
| 2664 | ++OtherIdx) { |
| 2665 | // We expect the AddRecExpr's to be sorted in reverse dominance order, |
| 2666 | // so that the 1st found AddRecExpr is dominated by all others. |
| 2667 | assert(DT.dominates((static_cast <bool> (DT.dominates( cast<SCEVAddRecExpr >(Ops[OtherIdx])->getLoop()->getHeader(), AddRec-> getLoop()->getHeader()) && "AddRecExprs are not sorted in reverse dominance order?" ) ? void (0) : __assert_fail ("DT.dominates( cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()->getHeader(), AddRec->getLoop()->getHeader()) && \"AddRecExprs are not sorted in reverse dominance order?\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 2670, __extension__ __PRETTY_FUNCTION__)) |
| 2668 | cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()->getHeader(),(static_cast <bool> (DT.dominates( cast<SCEVAddRecExpr >(Ops[OtherIdx])->getLoop()->getHeader(), AddRec-> getLoop()->getHeader()) && "AddRecExprs are not sorted in reverse dominance order?" ) ? void (0) : __assert_fail ("DT.dominates( cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()->getHeader(), AddRec->getLoop()->getHeader()) && \"AddRecExprs are not sorted in reverse dominance order?\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 2670, __extension__ __PRETTY_FUNCTION__)) |
| 2669 | AddRec->getLoop()->getHeader()) &&(static_cast <bool> (DT.dominates( cast<SCEVAddRecExpr >(Ops[OtherIdx])->getLoop()->getHeader(), AddRec-> getLoop()->getHeader()) && "AddRecExprs are not sorted in reverse dominance order?" ) ? void (0) : __assert_fail ("DT.dominates( cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()->getHeader(), AddRec->getLoop()->getHeader()) && \"AddRecExprs are not sorted in reverse dominance order?\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 2670, __extension__ __PRETTY_FUNCTION__)) |
| 2670 | "AddRecExprs are not sorted in reverse dominance order?")(static_cast <bool> (DT.dominates( cast<SCEVAddRecExpr >(Ops[OtherIdx])->getLoop()->getHeader(), AddRec-> getLoop()->getHeader()) && "AddRecExprs are not sorted in reverse dominance order?" ) ? void (0) : __assert_fail ("DT.dominates( cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()->getHeader(), AddRec->getLoop()->getHeader()) && \"AddRecExprs are not sorted in reverse dominance order?\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 2670, __extension__ __PRETTY_FUNCTION__)); |
| 2671 | if (AddRecLoop == cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()) { |
| 2672 | // Other + {A,+,B}<L> + {C,+,D}<L> --> Other + {A+C,+,B+D}<L> |
| 2673 | SmallVector<const SCEV *, 4> AddRecOps(AddRec->operands()); |
| 2674 | for (; OtherIdx != Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]); |
| 2675 | ++OtherIdx) { |
| 2676 | const auto *OtherAddRec = cast<SCEVAddRecExpr>(Ops[OtherIdx]); |
| 2677 | if (OtherAddRec->getLoop() == AddRecLoop) { |
| 2678 | for (unsigned i = 0, e = OtherAddRec->getNumOperands(); |
| 2679 | i != e; ++i) { |
| 2680 | if (i >= AddRecOps.size()) { |
| 2681 | AddRecOps.append(OtherAddRec->op_begin()+i, |
| 2682 | OtherAddRec->op_end()); |
| 2683 | break; |
| 2684 | } |
| 2685 | SmallVector<const SCEV *, 2> TwoOps = { |
| 2686 | AddRecOps[i], OtherAddRec->getOperand(i)}; |
| 2687 | AddRecOps[i] = getAddExpr(TwoOps, SCEV::FlagAnyWrap, Depth + 1); |
| 2688 | } |
| 2689 | Ops.erase(Ops.begin() + OtherIdx); --OtherIdx; |
| 2690 | } |
| 2691 | } |
| 2692 | // Step size has changed, so we cannot guarantee no self-wraparound. |
| 2693 | Ops[Idx] = getAddRecExpr(AddRecOps, AddRecLoop, SCEV::FlagAnyWrap); |
| 2694 | return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1); |
| 2695 | } |
| 2696 | } |
| 2697 | |
| 2698 | // Otherwise couldn't fold anything into this recurrence. Move onto the |
| 2699 | // next one. |
| 2700 | } |
| 2701 | |
| 2702 | // Okay, it looks like we really DO need an add expr. Check to see if we |
| 2703 | // already have one, otherwise create a new one. |
| 2704 | return getOrCreateAddExpr(Ops, ComputeFlags(Ops)); |
| 2705 | } |
| 2706 | |
| 2707 | const SCEV * |
| 2708 | ScalarEvolution::getOrCreateAddExpr(ArrayRef<const SCEV *> Ops, |
| 2709 | SCEV::NoWrapFlags Flags) { |
| 2710 | FoldingSetNodeID ID; |
| 2711 | ID.AddInteger(scAddExpr); |
| 2712 | for (const SCEV *Op : Ops) |
| 2713 | ID.AddPointer(Op); |
| 2714 | void *IP = nullptr; |
| 2715 | SCEVAddExpr *S = |
| 2716 | static_cast<SCEVAddExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP)); |
| 2717 | if (!S) { |
| 2718 | const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size()); |
| 2719 | std::uninitialized_copy(Ops.begin(), Ops.end(), O); |
| 2720 | S = new (SCEVAllocator) |
| 2721 | SCEVAddExpr(ID.Intern(SCEVAllocator), O, Ops.size()); |
| 2722 | UniqueSCEVs.InsertNode(S, IP); |
| 2723 | addToLoopUseLists(S); |
| 2724 | } |
| 2725 | S->setNoWrapFlags(Flags); |
| 2726 | return S; |
| 2727 | } |
| 2728 | |
| 2729 | const SCEV * |
| 2730 | ScalarEvolution::getOrCreateAddRecExpr(ArrayRef<const SCEV *> Ops, |
| 2731 | const Loop *L, SCEV::NoWrapFlags Flags) { |
| 2732 | FoldingSetNodeID ID; |
| 2733 | ID.AddInteger(scAddRecExpr); |
| 2734 | for (unsigned i = 0, e = Ops.size(); i != e; ++i) |
| 2735 | ID.AddPointer(Ops[i]); |
| 2736 | ID.AddPointer(L); |
| 2737 | void *IP = nullptr; |
| 2738 | SCEVAddRecExpr *S = |
| 2739 | static_cast<SCEVAddRecExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP)); |
| 2740 | if (!S) { |
| 2741 | const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size()); |
| 2742 | std::uninitialized_copy(Ops.begin(), Ops.end(), O); |
| 2743 | S = new (SCEVAllocator) |
| 2744 | SCEVAddRecExpr(ID.Intern(SCEVAllocator), O, Ops.size(), L); |
| 2745 | UniqueSCEVs.InsertNode(S, IP); |
| 2746 | addToLoopUseLists(S); |
| 2747 | } |
| 2748 | setNoWrapFlags(S, Flags); |
| 2749 | return S; |
| 2750 | } |
| 2751 | |
| 2752 | const SCEV * |
| 2753 | ScalarEvolution::getOrCreateMulExpr(ArrayRef<const SCEV *> Ops, |
| 2754 | SCEV::NoWrapFlags Flags) { |
| 2755 | FoldingSetNodeID ID; |
| 2756 | ID.AddInteger(scMulExpr); |
| 2757 | for (unsigned i = 0, e = Ops.size(); i != e; ++i) |
| 2758 | ID.AddPointer(Ops[i]); |
| 2759 | void *IP = nullptr; |
| 2760 | SCEVMulExpr *S = |
| 2761 | static_cast<SCEVMulExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP)); |
| 2762 | if (!S) { |
| 2763 | const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size()); |
| 2764 | std::uninitialized_copy(Ops.begin(), Ops.end(), O); |
| 2765 | S = new (SCEVAllocator) SCEVMulExpr(ID.Intern(SCEVAllocator), |
| 2766 | O, Ops.size()); |
| 2767 | UniqueSCEVs.InsertNode(S, IP); |
| 2768 | addToLoopUseLists(S); |
| 2769 | } |
| 2770 | S->setNoWrapFlags(Flags); |
| 2771 | return S; |
| 2772 | } |
| 2773 | |
| 2774 | static uint64_t umul_ov(uint64_t i, uint64_t j, bool &Overflow) { |
| 2775 | uint64_t k = i*j; |
| 2776 | if (j > 1 && k / j != i) Overflow = true; |
| 2777 | return k; |
| 2778 | } |
| 2779 | |
| 2780 | /// Compute the result of "n choose k", the binomial coefficient. If an |
| 2781 | /// intermediate computation overflows, Overflow will be set and the return will |
| 2782 | /// be garbage. Overflow is not cleared on absence of overflow. |
| 2783 | static uint64_t Choose(uint64_t n, uint64_t k, bool &Overflow) { |
| 2784 | // We use the multiplicative formula: |
| 2785 | // n(n-1)(n-2)...(n-(k-1)) / k(k-1)(k-2)...1 . |
| 2786 | // At each iteration, we take the n-th term of the numeral and divide by the |
| 2787 | // (k-n)th term of the denominator. This division will always produce an |
| 2788 | // integral result, and helps reduce the chance of overflow in the |
| 2789 | // intermediate computations. However, we can still overflow even when the |
| 2790 | // final result would fit. |
| 2791 | |
| 2792 | if (n == 0 || n == k) return 1; |
| 2793 | if (k > n) return 0; |
| 2794 | |
| 2795 | if (k > n/2) |
| 2796 | k = n-k; |
| 2797 | |
| 2798 | uint64_t r = 1; |
| 2799 | for (uint64_t i = 1; i <= k; ++i) { |
| 2800 | r = umul_ov(r, n-(i-1), Overflow); |
| 2801 | r /= i; |
| 2802 | } |
| 2803 | return r; |
| 2804 | } |
| 2805 | |
| 2806 | /// Determine if any of the operands in this SCEV are a constant or if |
| 2807 | /// any of the add or multiply expressions in this SCEV contain a constant. |
| 2808 | static bool containsConstantInAddMulChain(const SCEV *StartExpr) { |
| 2809 | struct FindConstantInAddMulChain { |
| 2810 | bool FoundConstant = false; |
| 2811 | |
| 2812 | bool follow(const SCEV *S) { |
| 2813 | FoundConstant |= isa<SCEVConstant>(S); |
| 2814 | return isa<SCEVAddExpr>(S) || isa<SCEVMulExpr>(S); |
| 2815 | } |
| 2816 | |
| 2817 | bool isDone() const { |
| 2818 | return FoundConstant; |
| 2819 | } |
| 2820 | }; |
| 2821 | |
| 2822 | FindConstantInAddMulChain F; |
| 2823 | SCEVTraversal<FindConstantInAddMulChain> ST(F); |
| 2824 | ST.visitAll(StartExpr); |
| 2825 | return F.FoundConstant; |
| 2826 | } |
| 2827 | |
| 2828 | /// Get a canonical multiply expression, or something simpler if possible. |
| 2829 | const SCEV *ScalarEvolution::getMulExpr(SmallVectorImpl<const SCEV *> &Ops, |
| 2830 | SCEV::NoWrapFlags OrigFlags, |
| 2831 | unsigned Depth) { |
| 2832 | assert(OrigFlags == maskFlags(OrigFlags, SCEV::FlagNUW | SCEV::FlagNSW) &&(static_cast <bool> (OrigFlags == maskFlags(OrigFlags, SCEV ::FlagNUW | SCEV::FlagNSW) && "only nuw or nsw allowed" ) ? void (0) : __assert_fail ("OrigFlags == maskFlags(OrigFlags, SCEV::FlagNUW | SCEV::FlagNSW) && \"only nuw or nsw allowed\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 2833, __extension__ __PRETTY_FUNCTION__)) |
| 2833 | "only nuw or nsw allowed")(static_cast <bool> (OrigFlags == maskFlags(OrigFlags, SCEV ::FlagNUW | SCEV::FlagNSW) && "only nuw or nsw allowed" ) ? void (0) : __assert_fail ("OrigFlags == maskFlags(OrigFlags, SCEV::FlagNUW | SCEV::FlagNSW) && \"only nuw or nsw allowed\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 2833, __extension__ __PRETTY_FUNCTION__)); |
| 2834 | assert(!Ops.empty() && "Cannot get empty mul!")(static_cast <bool> (!Ops.empty() && "Cannot get empty mul!" ) ? void (0) : __assert_fail ("!Ops.empty() && \"Cannot get empty mul!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 2834, __extension__ __PRETTY_FUNCTION__)); |
| 2835 | if (Ops.size() == 1) return Ops[0]; |
| 2836 | #ifndef NDEBUG |
| 2837 | Type *ETy = getEffectiveSCEVType(Ops[0]->getType()); |
| 2838 | for (unsigned i = 1, e = Ops.size(); i != e; ++i) |
| 2839 | assert(getEffectiveSCEVType(Ops[i]->getType()) == ETy &&(static_cast <bool> (getEffectiveSCEVType(Ops[i]->getType ()) == ETy && "SCEVMulExpr operand types don't match!" ) ? void (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVMulExpr operand types don't match!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 2840, __extension__ __PRETTY_FUNCTION__)) |
| 2840 | "SCEVMulExpr operand types don't match!")(static_cast <bool> (getEffectiveSCEVType(Ops[i]->getType ()) == ETy && "SCEVMulExpr operand types don't match!" ) ? void (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVMulExpr operand types don't match!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 2840, __extension__ __PRETTY_FUNCTION__)); |
| 2841 | #endif |
| 2842 | |
| 2843 | // Sort by complexity, this groups all similar expression types together. |
| 2844 | GroupByComplexity(Ops, &LI, DT); |
| 2845 | |
| 2846 | // If there are any constants, fold them together. |
| 2847 | unsigned Idx = 0; |
| 2848 | if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) { |
| 2849 | ++Idx; |
| 2850 | assert(Idx < Ops.size())(static_cast <bool> (Idx < Ops.size()) ? void (0) : __assert_fail ("Idx < Ops.size()", "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 2850, __extension__ __PRETTY_FUNCTION__)); |
| 2851 | while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) { |
| 2852 | // We found two constants, fold them together! |
| 2853 | Ops[0] = getConstant(LHSC->getAPInt() * RHSC->getAPInt()); |
| 2854 | if (Ops.size() == 2) return Ops[0]; |
| 2855 | Ops.erase(Ops.begin()+1); // Erase the folded element |
| 2856 | LHSC = cast<SCEVConstant>(Ops[0]); |
| 2857 | } |
| 2858 | |
| 2859 | // If we have a multiply of zero, it will always be zero. |
| 2860 | if (LHSC->getValue()->isZero()) |
| 2861 | return LHSC; |
| 2862 | |
| 2863 | // If we are left with a constant one being multiplied, strip it off. |
| 2864 | if (LHSC->getValue()->isOne()) { |
| 2865 | Ops.erase(Ops.begin()); |
| 2866 | --Idx; |
| 2867 | } |
| 2868 | |
| 2869 | if (Ops.size() == 1) |
| 2870 | return Ops[0]; |
| 2871 | } |
| 2872 | |
| 2873 | // Delay expensive flag strengthening until necessary. |
| 2874 | auto ComputeFlags = [this, OrigFlags](const ArrayRef<const SCEV *> Ops) { |
| 2875 | return StrengthenNoWrapFlags(this, scMulExpr, Ops, OrigFlags); |
| 2876 | }; |
| 2877 | |
| 2878 | // Limit recursion calls depth. |
| 2879 | if (Depth > MaxArithDepth || hasHugeExpression(Ops)) |
| 2880 | return getOrCreateMulExpr(Ops, ComputeFlags(Ops)); |
| 2881 | |
| 2882 | if (SCEV *S = std::get<0>(findExistingSCEVInCache(scMulExpr, Ops))) { |
| 2883 | // Don't strengthen flags if we have no new information. |
| 2884 | SCEVMulExpr *Mul = static_cast<SCEVMulExpr *>(S); |
| 2885 | if (Mul->getNoWrapFlags(OrigFlags) != OrigFlags) |
| 2886 | Mul->setNoWrapFlags(ComputeFlags(Ops)); |
| 2887 | return S; |
| 2888 | } |
| 2889 | |
| 2890 | if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) { |
| 2891 | if (Ops.size() == 2) { |
| 2892 | // C1*(C2+V) -> C1*C2 + C1*V |
| 2893 | if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[1])) |
| 2894 | // If any of Add's ops are Adds or Muls with a constant, apply this |
| 2895 | // transformation as well. |
| 2896 | // |
| 2897 | // TODO: There are some cases where this transformation is not |
| 2898 | // profitable; for example, Add = (C0 + X) * Y + Z. Maybe the scope of |
| 2899 | // this transformation should be narrowed down. |
| 2900 | if (Add->getNumOperands() == 2 && containsConstantInAddMulChain(Add)) |
| 2901 | return getAddExpr(getMulExpr(LHSC, Add->getOperand(0), |
| 2902 | SCEV::FlagAnyWrap, Depth + 1), |
| 2903 | getMulExpr(LHSC, Add->getOperand(1), |
| 2904 | SCEV::FlagAnyWrap, Depth + 1), |
| 2905 | SCEV::FlagAnyWrap, Depth + 1); |
| 2906 | |
| 2907 | if (Ops[0]->isAllOnesValue()) { |
| 2908 | // If we have a mul by -1 of an add, try distributing the -1 among the |
| 2909 | // add operands. |
| 2910 | if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[1])) { |
| 2911 | SmallVector<const SCEV *, 4> NewOps; |
| 2912 | bool AnyFolded = false; |
| 2913 | for (const SCEV *AddOp : Add->operands()) { |
| 2914 | const SCEV *Mul = getMulExpr(Ops[0], AddOp, SCEV::FlagAnyWrap, |
| 2915 | Depth + 1); |
| 2916 | if (!isa<SCEVMulExpr>(Mul)) AnyFolded = true; |
| 2917 | NewOps.push_back(Mul); |
| 2918 | } |
| 2919 | if (AnyFolded) |
| 2920 | return getAddExpr(NewOps, SCEV::FlagAnyWrap, Depth + 1); |
| 2921 | } else if (const auto *AddRec = dyn_cast<SCEVAddRecExpr>(Ops[1])) { |
| 2922 | // Negation preserves a recurrence's no self-wrap property. |
| 2923 | SmallVector<const SCEV *, 4> Operands; |
| 2924 | for (const SCEV *AddRecOp : AddRec->operands()) |
| 2925 | Operands.push_back(getMulExpr(Ops[0], AddRecOp, SCEV::FlagAnyWrap, |
| 2926 | Depth + 1)); |
| 2927 | |
| 2928 | return getAddRecExpr(Operands, AddRec->getLoop(), |
| 2929 | AddRec->getNoWrapFlags(SCEV::FlagNW)); |
| 2930 | } |
| 2931 | } |
| 2932 | } |
| 2933 | } |
| 2934 | |
| 2935 | // Skip over the add expression until we get to a multiply. |
| 2936 | while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scMulExpr) |
| 2937 | ++Idx; |
| 2938 | |
| 2939 | // If there are mul operands inline them all into this expression. |
| 2940 | if (Idx < Ops.size()) { |
| 2941 | bool DeletedMul = false; |
| 2942 | while (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(Ops[Idx])) { |
| 2943 | if (Ops.size() > MulOpsInlineThreshold) |
| 2944 | break; |
| 2945 | // If we have an mul, expand the mul operands onto the end of the |
| 2946 | // operands list. |
| 2947 | Ops.erase(Ops.begin()+Idx); |
| 2948 | Ops.append(Mul->op_begin(), Mul->op_end()); |
| 2949 | DeletedMul = true; |
| 2950 | } |
| 2951 | |
| 2952 | // If we deleted at least one mul, we added operands to the end of the |
| 2953 | // list, and they are not necessarily sorted. Recurse to resort and |
| 2954 | // resimplify any operands we just acquired. |
| 2955 | if (DeletedMul) |
| 2956 | return getMulExpr(Ops, SCEV::FlagAnyWrap, Depth + 1); |
| 2957 | } |
| 2958 | |
| 2959 | // If there are any add recurrences in the operands list, see if any other |
| 2960 | // added values are loop invariant. If so, we can fold them into the |
| 2961 | // recurrence. |
| 2962 | while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddRecExpr) |
| 2963 | ++Idx; |
| 2964 | |
| 2965 | // Scan over all recurrences, trying to fold loop invariants into them. |
| 2966 | for (; Idx < Ops.size() && isa<SCEVAddRecExpr>(Ops[Idx]); ++Idx) { |
| 2967 | // Scan all of the other operands to this mul and add them to the vector |
| 2968 | // if they are loop invariant w.r.t. the recurrence. |
| 2969 | SmallVector<const SCEV *, 8> LIOps; |
| 2970 | const SCEVAddRecExpr *AddRec = cast<SCEVAddRecExpr>(Ops[Idx]); |
| 2971 | const Loop *AddRecLoop = AddRec->getLoop(); |
| 2972 | for (unsigned i = 0, e = Ops.size(); i != e; ++i) |
| 2973 | if (isAvailableAtLoopEntry(Ops[i], AddRecLoop)) { |
| 2974 | LIOps.push_back(Ops[i]); |
| 2975 | Ops.erase(Ops.begin()+i); |
| 2976 | --i; --e; |
| 2977 | } |
| 2978 | |
| 2979 | // If we found some loop invariants, fold them into the recurrence. |
| 2980 | if (!LIOps.empty()) { |
| 2981 | // NLI * LI * {Start,+,Step} --> NLI * {LI*Start,+,LI*Step} |
| 2982 | SmallVector<const SCEV *, 4> NewOps; |
| 2983 | NewOps.reserve(AddRec->getNumOperands()); |
| 2984 | const SCEV *Scale = getMulExpr(LIOps, SCEV::FlagAnyWrap, Depth + 1); |
| 2985 | for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i) |
| 2986 | NewOps.push_back(getMulExpr(Scale, AddRec->getOperand(i), |
| 2987 | SCEV::FlagAnyWrap, Depth + 1)); |
| 2988 | |
| 2989 | // Build the new addrec. Propagate the NUW and NSW flags if both the |
| 2990 | // outer mul and the inner addrec are guaranteed to have no overflow. |
| 2991 | // |
| 2992 | // No self-wrap cannot be guaranteed after changing the step size, but |
| 2993 | // will be inferred if either NUW or NSW is true. |
| 2994 | SCEV::NoWrapFlags Flags = ComputeFlags({Scale, AddRec}); |
| 2995 | const SCEV *NewRec = getAddRecExpr( |
| 2996 | NewOps, AddRecLoop, AddRec->getNoWrapFlags(Flags)); |
| 2997 | |
| 2998 | // If all of the other operands were loop invariant, we are done. |
| 2999 | if (Ops.size() == 1) return NewRec; |
| 3000 | |
| 3001 | // Otherwise, multiply the folded AddRec by the non-invariant parts. |
| 3002 | for (unsigned i = 0;; ++i) |
| 3003 | if (Ops[i] == AddRec) { |
| 3004 | Ops[i] = NewRec; |
| 3005 | break; |
| 3006 | } |
| 3007 | return getMulExpr(Ops, SCEV::FlagAnyWrap, Depth + 1); |
| 3008 | } |
| 3009 | |
| 3010 | // Okay, if there weren't any loop invariants to be folded, check to see |
| 3011 | // if there are multiple AddRec's with the same loop induction variable |
| 3012 | // being multiplied together. If so, we can fold them. |
| 3013 | |
| 3014 | // {A1,+,A2,+,...,+,An}<L> * {B1,+,B2,+,...,+,Bn}<L> |
| 3015 | // = {x=1 in [ sum y=x..2x [ sum z=max(y-x, y-n)..min(x,n) [ |
| 3016 | // choose(x, 2x)*choose(2x-y, x-z)*A_{y-z}*B_z |
| 3017 | // ]]],+,...up to x=2n}. |
| 3018 | // Note that the arguments to choose() are always integers with values |
| 3019 | // known at compile time, never SCEV objects. |
| 3020 | // |
| 3021 | // The implementation avoids pointless extra computations when the two |
| 3022 | // addrec's are of different length (mathematically, it's equivalent to |
| 3023 | // an infinite stream of zeros on the right). |
| 3024 | bool OpsModified = false; |
| 3025 | for (unsigned OtherIdx = Idx+1; |
| 3026 | OtherIdx != Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]); |
| 3027 | ++OtherIdx) { |
| 3028 | const SCEVAddRecExpr *OtherAddRec = |
| 3029 | dyn_cast<SCEVAddRecExpr>(Ops[OtherIdx]); |
| 3030 | if (!OtherAddRec || OtherAddRec->getLoop() != AddRecLoop) |
| 3031 | continue; |
| 3032 | |
| 3033 | // Limit max number of arguments to avoid creation of unreasonably big |
| 3034 | // SCEVAddRecs with very complex operands. |
| 3035 | if (AddRec->getNumOperands() + OtherAddRec->getNumOperands() - 1 > |
| 3036 | MaxAddRecSize || hasHugeExpression({AddRec, OtherAddRec})) |
| 3037 | continue; |
| 3038 | |
| 3039 | bool Overflow = false; |
| 3040 | Type *Ty = AddRec->getType(); |
| 3041 | bool LargerThan64Bits = getTypeSizeInBits(Ty) > 64; |
| 3042 | SmallVector<const SCEV*, 7> AddRecOps; |
| 3043 | for (int x = 0, xe = AddRec->getNumOperands() + |
| 3044 | OtherAddRec->getNumOperands() - 1; x != xe && !Overflow; ++x) { |
| 3045 | SmallVector <const SCEV *, 7> SumOps; |
| 3046 | for (int y = x, ye = 2*x+1; y != ye && !Overflow; ++y) { |
| 3047 | uint64_t Coeff1 = Choose(x, 2*x - y, Overflow); |
| 3048 | for (int z = std::max(y-x, y-(int)AddRec->getNumOperands()+1), |
| 3049 | ze = std::min(x+1, (int)OtherAddRec->getNumOperands()); |
| 3050 | z < ze && !Overflow; ++z) { |
| 3051 | uint64_t Coeff2 = Choose(2*x - y, x-z, Overflow); |
| 3052 | uint64_t Coeff; |
| 3053 | if (LargerThan64Bits) |
| 3054 | Coeff = umul_ov(Coeff1, Coeff2, Overflow); |
| 3055 | else |
| 3056 | Coeff = Coeff1*Coeff2; |
| 3057 | const SCEV *CoeffTerm = getConstant(Ty, Coeff); |
| 3058 | const SCEV *Term1 = AddRec->getOperand(y-z); |
| 3059 | const SCEV *Term2 = OtherAddRec->getOperand(z); |
| 3060 | SumOps.push_back(getMulExpr(CoeffTerm, Term1, Term2, |
| 3061 | SCEV::FlagAnyWrap, Depth + 1)); |
| 3062 | } |
| 3063 | } |
| 3064 | if (SumOps.empty()) |
| 3065 | SumOps.push_back(getZero(Ty)); |
| 3066 | AddRecOps.push_back(getAddExpr(SumOps, SCEV::FlagAnyWrap, Depth + 1)); |
| 3067 | } |
| 3068 | if (!Overflow) { |
| 3069 | const SCEV *NewAddRec = getAddRecExpr(AddRecOps, AddRecLoop, |
| 3070 | SCEV::FlagAnyWrap); |
| 3071 | if (Ops.size() == 2) return NewAddRec; |
| 3072 | Ops[Idx] = NewAddRec; |
| 3073 | Ops.erase(Ops.begin() + OtherIdx); --OtherIdx; |
| 3074 | OpsModified = true; |
| 3075 | AddRec = dyn_cast<SCEVAddRecExpr>(NewAddRec); |
| 3076 | if (!AddRec) |
| 3077 | break; |
| 3078 | } |
| 3079 | } |
| 3080 | if (OpsModified) |
| 3081 | return getMulExpr(Ops, SCEV::FlagAnyWrap, Depth + 1); |
| 3082 | |
| 3083 | // Otherwise couldn't fold anything into this recurrence. Move onto the |
| 3084 | // next one. |
| 3085 | } |
| 3086 | |
| 3087 | // Okay, it looks like we really DO need an mul expr. Check to see if we |
| 3088 | // already have one, otherwise create a new one. |
| 3089 | return getOrCreateMulExpr(Ops, ComputeFlags(Ops)); |
| 3090 | } |
| 3091 | |
| 3092 | /// Represents an unsigned remainder expression based on unsigned division. |
| 3093 | const SCEV *ScalarEvolution::getURemExpr(const SCEV *LHS, |
| 3094 | const SCEV *RHS) { |
| 3095 | assert(getEffectiveSCEVType(LHS->getType()) ==(static_cast <bool> (getEffectiveSCEVType(LHS->getType ()) == getEffectiveSCEVType(RHS->getType()) && "SCEVURemExpr operand types don't match!" ) ? void (0) : __assert_fail ("getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType(RHS->getType()) && \"SCEVURemExpr operand types don't match!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 3097, __extension__ __PRETTY_FUNCTION__)) |
| 3096 | getEffectiveSCEVType(RHS->getType()) &&(static_cast <bool> (getEffectiveSCEVType(LHS->getType ()) == getEffectiveSCEVType(RHS->getType()) && "SCEVURemExpr operand types don't match!" ) ? void (0) : __assert_fail ("getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType(RHS->getType()) && \"SCEVURemExpr operand types don't match!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 3097, __extension__ __PRETTY_FUNCTION__)) |
| 3097 | "SCEVURemExpr operand types don't match!")(static_cast <bool> (getEffectiveSCEVType(LHS->getType ()) == getEffectiveSCEVType(RHS->getType()) && "SCEVURemExpr operand types don't match!" ) ? void (0) : __assert_fail ("getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType(RHS->getType()) && \"SCEVURemExpr operand types don't match!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 3097, __extension__ __PRETTY_FUNCTION__)); |
| 3098 | |
| 3099 | // Short-circuit easy cases |
| 3100 | if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS)) { |
| 3101 | // If constant is one, the result is trivial |
| 3102 | if (RHSC->getValue()->isOne()) |
| 3103 | return getZero(LHS->getType()); // X urem 1 --> 0 |
| 3104 | |
| 3105 | // If constant is a power of two, fold into a zext(trunc(LHS)). |
| 3106 | if (RHSC->getAPInt().isPowerOf2()) { |
| 3107 | Type *FullTy = LHS->getType(); |
| 3108 | Type *TruncTy = |
| 3109 | IntegerType::get(getContext(), RHSC->getAPInt().logBase2()); |
| 3110 | return getZeroExtendExpr(getTruncateExpr(LHS, TruncTy), FullTy); |
| 3111 | } |
| 3112 | } |
| 3113 | |
| 3114 | // Fallback to %a == %x urem %y == %x -<nuw> ((%x udiv %y) *<nuw> %y) |
| 3115 | const SCEV *UDiv = getUDivExpr(LHS, RHS); |
| 3116 | const SCEV *Mult = getMulExpr(UDiv, RHS, SCEV::FlagNUW); |
| 3117 | return getMinusSCEV(LHS, Mult, SCEV::FlagNUW); |
| 3118 | } |
| 3119 | |
| 3120 | /// Get a canonical unsigned division expression, or something simpler if |
| 3121 | /// possible. |
| 3122 | const SCEV *ScalarEvolution::getUDivExpr(const SCEV *LHS, |
| 3123 | const SCEV *RHS) { |
| 3124 | assert(getEffectiveSCEVType(LHS->getType()) ==(static_cast <bool> (getEffectiveSCEVType(LHS->getType ()) == getEffectiveSCEVType(RHS->getType()) && "SCEVUDivExpr operand types don't match!" ) ? void (0) : __assert_fail ("getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType(RHS->getType()) && \"SCEVUDivExpr operand types don't match!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 3126, __extension__ __PRETTY_FUNCTION__)) |
| 3125 | getEffectiveSCEVType(RHS->getType()) &&(static_cast <bool> (getEffectiveSCEVType(LHS->getType ()) == getEffectiveSCEVType(RHS->getType()) && "SCEVUDivExpr operand types don't match!" ) ? void (0) : __assert_fail ("getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType(RHS->getType()) && \"SCEVUDivExpr operand types don't match!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 3126, __extension__ __PRETTY_FUNCTION__)) |
| 3126 | "SCEVUDivExpr operand types don't match!")(static_cast <bool> (getEffectiveSCEVType(LHS->getType ()) == getEffectiveSCEVType(RHS->getType()) && "SCEVUDivExpr operand types don't match!" ) ? void (0) : __assert_fail ("getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType(RHS->getType()) && \"SCEVUDivExpr operand types don't match!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 3126, __extension__ __PRETTY_FUNCTION__)); |
| 3127 | |
| 3128 | FoldingSetNodeID ID; |
| 3129 | ID.AddInteger(scUDivExpr); |
| 3130 | ID.AddPointer(LHS); |
| 3131 | ID.AddPointer(RHS); |
| 3132 | void *IP = nullptr; |
| 3133 | if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) |
| 3134 | return S; |
| 3135 | |
| 3136 | if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS)) { |
| 3137 | if (RHSC->getValue()->isOne()) |
| 3138 | return LHS; // X udiv 1 --> x |
| 3139 | // If the denominator is zero, the result of the udiv is undefined. Don't |
| 3140 | // try to analyze it, because the resolution chosen here may differ from |
| 3141 | // the resolution chosen in other parts of the compiler. |
| 3142 | if (!RHSC->getValue()->isZero()) { |
| 3143 | // Determine if the division can be folded into the operands of |
| 3144 | // its operands. |
| 3145 | // TODO: Generalize this to non-constants by using known-bits information. |
| 3146 | Type *Ty = LHS->getType(); |
| 3147 | unsigned LZ = RHSC->getAPInt().countLeadingZeros(); |
| 3148 | unsigned MaxShiftAmt = getTypeSizeInBits(Ty) - LZ - 1; |
| 3149 | // For non-power-of-two values, effectively round the value up to the |
| 3150 | // nearest power of two. |
| 3151 | if (!RHSC->getAPInt().isPowerOf2()) |
| 3152 | ++MaxShiftAmt; |
| 3153 | IntegerType *ExtTy = |
| 3154 | IntegerType::get(getContext(), getTypeSizeInBits(Ty) + MaxShiftAmt); |
| 3155 | if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(LHS)) |
| 3156 | if (const SCEVConstant *Step = |
| 3157 | dyn_cast<SCEVConstant>(AR->getStepRecurrence(*this))) { |
| 3158 | // {X,+,N}/C --> {X/C,+,N/C} if safe and N/C can be folded. |
| 3159 | const APInt &StepInt = Step->getAPInt(); |
| 3160 | const APInt &DivInt = RHSC->getAPInt(); |
| 3161 | if (!StepInt.urem(DivInt) && |
| 3162 | getZeroExtendExpr(AR, ExtTy) == |
| 3163 | getAddRecExpr(getZeroExtendExpr(AR->getStart(), ExtTy), |
| 3164 | getZeroExtendExpr(Step, ExtTy), |
| 3165 | AR->getLoop(), SCEV::FlagAnyWrap)) { |
| 3166 | SmallVector<const SCEV *, 4> Operands; |
| 3167 | for (const SCEV *Op : AR->operands()) |
| 3168 | Operands.push_back(getUDivExpr(Op, RHS)); |
| 3169 | return getAddRecExpr(Operands, AR->getLoop(), SCEV::FlagNW); |
| 3170 | } |
| 3171 | /// Get a canonical UDivExpr for a recurrence. |
| 3172 | /// {X,+,N}/C => {Y,+,N}/C where Y=X-(X%N). Safe when C%N=0. |
| 3173 | // We can currently only fold X%N if X is constant. |
| 3174 | const SCEVConstant *StartC = dyn_cast<SCEVConstant>(AR->getStart()); |
| 3175 | if (StartC && !DivInt.urem(StepInt) && |
| 3176 | getZeroExtendExpr(AR, ExtTy) == |
| 3177 | getAddRecExpr(getZeroExtendExpr(AR->getStart(), ExtTy), |
| 3178 | getZeroExtendExpr(Step, ExtTy), |
| 3179 | AR->getLoop(), SCEV::FlagAnyWrap)) { |
| 3180 | const APInt &StartInt = StartC->getAPInt(); |
| 3181 | const APInt &StartRem = StartInt.urem(StepInt); |
| 3182 | if (StartRem != 0) { |
| 3183 | const SCEV *NewLHS = |
| 3184 | getAddRecExpr(getConstant(StartInt - StartRem), Step, |
| 3185 | AR->getLoop(), SCEV::FlagNW); |
| 3186 | if (LHS != NewLHS) { |
| 3187 | LHS = NewLHS; |
| 3188 | |
| 3189 | // Reset the ID to include the new LHS, and check if it is |
| 3190 | // already cached. |
| 3191 | ID.clear(); |
| 3192 | ID.AddInteger(scUDivExpr); |
| 3193 | ID.AddPointer(LHS); |
| 3194 | ID.AddPointer(RHS); |
| 3195 | IP = nullptr; |
| 3196 | if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) |
| 3197 | return S; |
| 3198 | } |
| 3199 | } |
| 3200 | } |
| 3201 | } |
| 3202 | // (A*B)/C --> A*(B/C) if safe and B/C can be folded. |
| 3203 | if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(LHS)) { |
| 3204 | SmallVector<const SCEV *, 4> Operands; |
| 3205 | for (const SCEV *Op : M->operands()) |
| 3206 | Operands.push_back(getZeroExtendExpr(Op, ExtTy)); |
| 3207 | if (getZeroExtendExpr(M, ExtTy) == getMulExpr(Operands)) |
| 3208 | // Find an operand that's safely divisible. |
| 3209 | for (unsigned i = 0, e = M->getNumOperands(); i != e; ++i) { |
| 3210 | const SCEV *Op = M->getOperand(i); |
| 3211 | const SCEV *Div = getUDivExpr(Op, RHSC); |
| 3212 | if (!isa<SCEVUDivExpr>(Div) && getMulExpr(Div, RHSC) == Op) { |
| 3213 | Operands = SmallVector<const SCEV *, 4>(M->operands()); |
| 3214 | Operands[i] = Div; |
| 3215 | return getMulExpr(Operands); |
| 3216 | } |
| 3217 | } |
| 3218 | } |
| 3219 | |
| 3220 | // (A/B)/C --> A/(B*C) if safe and B*C can be folded. |
| 3221 | if (const SCEVUDivExpr *OtherDiv = dyn_cast<SCEVUDivExpr>(LHS)) { |
| 3222 | if (auto *DivisorConstant = |
| 3223 | dyn_cast<SCEVConstant>(OtherDiv->getRHS())) { |
| 3224 | bool Overflow = false; |
| 3225 | APInt NewRHS = |
| 3226 | DivisorConstant->getAPInt().umul_ov(RHSC->getAPInt(), Overflow); |
| 3227 | if (Overflow) { |
| 3228 | return getConstant(RHSC->getType(), 0, false); |
| 3229 | } |
| 3230 | return getUDivExpr(OtherDiv->getLHS(), getConstant(NewRHS)); |
| 3231 | } |
| 3232 | } |
| 3233 | |
| 3234 | // (A+B)/C --> (A/C + B/C) if safe and A/C and B/C can be folded. |
| 3235 | if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(LHS)) { |
| 3236 | SmallVector<const SCEV *, 4> Operands; |
| 3237 | for (const SCEV *Op : A->operands()) |
| 3238 | Operands.push_back(getZeroExtendExpr(Op, ExtTy)); |
| 3239 | if (getZeroExtendExpr(A, ExtTy) == getAddExpr(Operands)) { |
| 3240 | Operands.clear(); |
| 3241 | for (unsigned i = 0, e = A->getNumOperands(); i != e; ++i) { |
| 3242 | const SCEV *Op = getUDivExpr(A->getOperand(i), RHS); |
| 3243 | if (isa<SCEVUDivExpr>(Op) || |
| 3244 | getMulExpr(Op, RHS) != A->getOperand(i)) |
| 3245 | break; |
| 3246 | Operands.push_back(Op); |
| 3247 | } |
| 3248 | if (Operands.size() == A->getNumOperands()) |
| 3249 | return getAddExpr(Operands); |
| 3250 | } |
| 3251 | } |
| 3252 | |
| 3253 | // Fold if both operands are constant. |
| 3254 | if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(LHS)) { |
| 3255 | Constant *LHSCV = LHSC->getValue(); |
| 3256 | Constant *RHSCV = RHSC->getValue(); |
| 3257 | return getConstant(cast<ConstantInt>(ConstantExpr::getUDiv(LHSCV, |
| 3258 | RHSCV))); |
| 3259 | } |
| 3260 | } |
| 3261 | } |
| 3262 | |
| 3263 | // The Insertion Point (IP) might be invalid by now (due to UniqueSCEVs |
| 3264 | // changes). Make sure we get a new one. |
| 3265 | IP = nullptr; |
| 3266 | if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S; |
| 3267 | SCEV *S = new (SCEVAllocator) SCEVUDivExpr(ID.Intern(SCEVAllocator), |
| 3268 | LHS, RHS); |
| 3269 | UniqueSCEVs.InsertNode(S, IP); |
| 3270 | addToLoopUseLists(S); |
| 3271 | return S; |
| 3272 | } |
| 3273 | |
| 3274 | static const APInt gcd(const SCEVConstant *C1, const SCEVConstant *C2) { |
| 3275 | APInt A = C1->getAPInt().abs(); |
| 3276 | APInt B = C2->getAPInt().abs(); |
| 3277 | uint32_t ABW = A.getBitWidth(); |
| 3278 | uint32_t BBW = B.getBitWidth(); |
| 3279 | |
| 3280 | if (ABW > BBW) |
| 3281 | B = B.zext(ABW); |
| 3282 | else if (ABW < BBW) |
| 3283 | A = A.zext(BBW); |
| 3284 | |
| 3285 | return APIntOps::GreatestCommonDivisor(std::move(A), std::move(B)); |
| 3286 | } |
| 3287 | |
| 3288 | /// Get a canonical unsigned division expression, or something simpler if |
| 3289 | /// possible. There is no representation for an exact udiv in SCEV IR, but we |
| 3290 | /// can attempt to remove factors from the LHS and RHS. We can't do this when |
| 3291 | /// it's not exact because the udiv may be clearing bits. |
| 3292 | const SCEV *ScalarEvolution::getUDivExactExpr(const SCEV *LHS, |
| 3293 | const SCEV *RHS) { |
| 3294 | // TODO: we could try to find factors in all sorts of things, but for now we |
| 3295 | // just deal with u/exact (multiply, constant). See SCEVDivision towards the |
| 3296 | // end of this file for inspiration. |
| 3297 | |
| 3298 | const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(LHS); |
| 3299 | if (!Mul || !Mul->hasNoUnsignedWrap()) |
| 3300 | return getUDivExpr(LHS, RHS); |
| 3301 | |
| 3302 | if (const SCEVConstant *RHSCst = dyn_cast<SCEVConstant>(RHS)) { |
| 3303 | // If the mulexpr multiplies by a constant, then that constant must be the |
| 3304 | // first element of the mulexpr. |
| 3305 | if (const auto *LHSCst = dyn_cast<SCEVConstant>(Mul->getOperand(0))) { |
| 3306 | if (LHSCst == RHSCst) { |
| 3307 | SmallVector<const SCEV *, 2> Operands(drop_begin(Mul->operands())); |
| 3308 | return getMulExpr(Operands); |
| 3309 | } |
| 3310 | |
| 3311 | // We can't just assume that LHSCst divides RHSCst cleanly, it could be |
| 3312 | // that there's a factor provided by one of the other terms. We need to |
| 3313 | // check. |
| 3314 | APInt Factor = gcd(LHSCst, RHSCst); |
| 3315 | if (!Factor.isIntN(1)) { |
| 3316 | LHSCst = |
| 3317 | cast<SCEVConstant>(getConstant(LHSCst->getAPInt().udiv(Factor))); |
| 3318 | RHSCst = |
| 3319 | cast<SCEVConstant>(getConstant(RHSCst->getAPInt().udiv(Factor))); |
| 3320 | SmallVector<const SCEV *, 2> Operands; |
| 3321 | Operands.push_back(LHSCst); |
| 3322 | Operands.append(Mul->op_begin() + 1, Mul->op_end()); |
| 3323 | LHS = getMulExpr(Operands); |
| 3324 | RHS = RHSCst; |
| 3325 | Mul = dyn_cast<SCEVMulExpr>(LHS); |
| 3326 | if (!Mul) |
| 3327 | return getUDivExactExpr(LHS, RHS); |
| 3328 | } |
| 3329 | } |
| 3330 | } |
| 3331 | |
| 3332 | for (int i = 0, e = Mul->getNumOperands(); i != e; ++i) { |
| 3333 | if (Mul->getOperand(i) == RHS) { |
| 3334 | SmallVector<const SCEV *, 2> Operands; |
| 3335 | Operands.append(Mul->op_begin(), Mul->op_begin() + i); |
| 3336 | Operands.append(Mul->op_begin() + i + 1, Mul->op_end()); |
| 3337 | return getMulExpr(Operands); |
| 3338 | } |
| 3339 | } |
| 3340 | |
| 3341 | return getUDivExpr(LHS, RHS); |
| 3342 | } |
| 3343 | |
| 3344 | /// Get an add recurrence expression for the specified loop. Simplify the |
| 3345 | /// expression as much as possible. |
| 3346 | const SCEV *ScalarEvolution::getAddRecExpr(const SCEV *Start, const SCEV *Step, |
| 3347 | const Loop *L, |
| 3348 | SCEV::NoWrapFlags Flags) { |
| 3349 | SmallVector<const SCEV *, 4> Operands; |
| 3350 | Operands.push_back(Start); |
| 3351 | if (const SCEVAddRecExpr *StepChrec = dyn_cast<SCEVAddRecExpr>(Step)) |
| 3352 | if (StepChrec->getLoop() == L) { |
| 3353 | Operands.append(StepChrec->op_begin(), StepChrec->op_end()); |
| 3354 | return getAddRecExpr(Operands, L, maskFlags(Flags, SCEV::FlagNW)); |
| 3355 | } |
| 3356 | |
| 3357 | Operands.push_back(Step); |
| 3358 | return getAddRecExpr(Operands, L, Flags); |
| 3359 | } |
| 3360 | |
| 3361 | /// Get an add recurrence expression for the specified loop. Simplify the |
| 3362 | /// expression as much as possible. |
| 3363 | const SCEV * |
| 3364 | ScalarEvolution::getAddRecExpr(SmallVectorImpl<const SCEV *> &Operands, |
| 3365 | const Loop *L, SCEV::NoWrapFlags Flags) { |
| 3366 | if (Operands.size() == 1) return Operands[0]; |
| 3367 | #ifndef NDEBUG |
| 3368 | Type *ETy = getEffectiveSCEVType(Operands[0]->getType()); |
| 3369 | for (unsigned i = 1, e = Operands.size(); i != e; ++i) |
| 3370 | assert(getEffectiveSCEVType(Operands[i]->getType()) == ETy &&(static_cast <bool> (getEffectiveSCEVType(Operands[i]-> getType()) == ETy && "SCEVAddRecExpr operand types don't match!" ) ? void (0) : __assert_fail ("getEffectiveSCEVType(Operands[i]->getType()) == ETy && \"SCEVAddRecExpr operand types don't match!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 3371, __extension__ __PRETTY_FUNCTION__)) |
| 3371 | "SCEVAddRecExpr operand types don't match!")(static_cast <bool> (getEffectiveSCEVType(Operands[i]-> getType()) == ETy && "SCEVAddRecExpr operand types don't match!" ) ? void (0) : __assert_fail ("getEffectiveSCEVType(Operands[i]->getType()) == ETy && \"SCEVAddRecExpr operand types don't match!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 3371, __extension__ __PRETTY_FUNCTION__)); |
| 3372 | for (unsigned i = 0, e = Operands.size(); i != e; ++i) |
| 3373 | assert(isLoopInvariant(Operands[i], L) &&(static_cast <bool> (isLoopInvariant(Operands[i], L) && "SCEVAddRecExpr operand is not loop-invariant!") ? void (0) : __assert_fail ("isLoopInvariant(Operands[i], L) && \"SCEVAddRecExpr operand is not loop-invariant!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 3374, __extension__ __PRETTY_FUNCTION__)) |
| 3374 | "SCEVAddRecExpr operand is not loop-invariant!")(static_cast <bool> (isLoopInvariant(Operands[i], L) && "SCEVAddRecExpr operand is not loop-invariant!") ? void (0) : __assert_fail ("isLoopInvariant(Operands[i], L) && \"SCEVAddRecExpr operand is not loop-invariant!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 3374, __extension__ __PRETTY_FUNCTION__)); |
| 3375 | #endif |
| 3376 | |
| 3377 | if (Operands.back()->isZero()) { |
| 3378 | Operands.pop_back(); |
| 3379 | return getAddRecExpr(Operands, L, SCEV::FlagAnyWrap); // {X,+,0} --> X |
| 3380 | } |
| 3381 | |
| 3382 | // It's tempting to want to call getConstantMaxBackedgeTakenCount count here and |
| 3383 | // use that information to infer NUW and NSW flags. However, computing a |
| 3384 | // BE count requires calling getAddRecExpr, so we may not yet have a |
| 3385 | // meaningful BE count at this point (and if we don't, we'd be stuck |
| 3386 | // with a SCEVCouldNotCompute as the cached BE count). |
| 3387 | |
| 3388 | Flags = StrengthenNoWrapFlags(this, scAddRecExpr, Operands, Flags); |
| 3389 | |
| 3390 | // Canonicalize nested AddRecs in by nesting them in order of loop depth. |
| 3391 | if (const SCEVAddRecExpr *NestedAR = dyn_cast<SCEVAddRecExpr>(Operands[0])) { |
| 3392 | const Loop *NestedLoop = NestedAR->getLoop(); |
| 3393 | if (L->contains(NestedLoop) |
| 3394 | ? (L->getLoopDepth() < NestedLoop->getLoopDepth()) |
| 3395 | : (!NestedLoop->contains(L) && |
| 3396 | DT.dominates(L->getHeader(), NestedLoop->getHeader()))) { |
| 3397 | SmallVector<const SCEV *, 4> NestedOperands(NestedAR->operands()); |
| 3398 | Operands[0] = NestedAR->getStart(); |
| 3399 | // AddRecs require their operands be loop-invariant with respect to their |
| 3400 | // loops. Don't perform this transformation if it would break this |
| 3401 | // requirement. |
| 3402 | bool AllInvariant = all_of( |
| 3403 | Operands, [&](const SCEV *Op) { return isLoopInvariant(Op, L); }); |
| 3404 | |
| 3405 | if (AllInvariant) { |
| 3406 | // Create a recurrence for the outer loop with the same step size. |
| 3407 | // |
| 3408 | // The outer recurrence keeps its NW flag but only keeps NUW/NSW if the |
| 3409 | // inner recurrence has the same property. |
| 3410 | SCEV::NoWrapFlags OuterFlags = |
| 3411 | maskFlags(Flags, SCEV::FlagNW | NestedAR->getNoWrapFlags()); |
| 3412 | |
| 3413 | NestedOperands[0] = getAddRecExpr(Operands, L, OuterFlags); |
| 3414 | AllInvariant = all_of(NestedOperands, [&](const SCEV *Op) { |
| 3415 | return isLoopInvariant(Op, NestedLoop); |
| 3416 | }); |
| 3417 | |
| 3418 | if (AllInvariant) { |
| 3419 | // Ok, both add recurrences are valid after the transformation. |
| 3420 | // |
| 3421 | // The inner recurrence keeps its NW flag but only keeps NUW/NSW if |
| 3422 | // the outer recurrence has the same property. |
| 3423 | SCEV::NoWrapFlags InnerFlags = |
| 3424 | maskFlags(NestedAR->getNoWrapFlags(), SCEV::FlagNW | Flags); |
| 3425 | return getAddRecExpr(NestedOperands, NestedLoop, InnerFlags); |
| 3426 | } |
| 3427 | } |
| 3428 | // Reset Operands to its original state. |
| 3429 | Operands[0] = NestedAR; |
| 3430 | } |
| 3431 | } |
| 3432 | |
| 3433 | // Okay, it looks like we really DO need an addrec expr. Check to see if we |
| 3434 | // already have one, otherwise create a new one. |
| 3435 | return getOrCreateAddRecExpr(Operands, L, Flags); |
| 3436 | } |
| 3437 | |
| 3438 | const SCEV * |
| 3439 | ScalarEvolution::getGEPExpr(GEPOperator *GEP, |
| 3440 | const SmallVectorImpl<const SCEV *> &IndexExprs) { |
| 3441 | const SCEV *BaseExpr = getSCEV(GEP->getPointerOperand()); |
| 3442 | // getSCEV(Base)->getType() has the same address space as Base->getType() |
| 3443 | // because SCEV::getType() preserves the address space. |
| 3444 | Type *IntIdxTy = getEffectiveSCEVType(BaseExpr->getType()); |
| 3445 | // FIXME(PR23527): Don't blindly transfer the inbounds flag from the GEP |
| 3446 | // instruction to its SCEV, because the Instruction may be guarded by control |
| 3447 | // flow and the no-overflow bits may not be valid for the expression in any |
| 3448 | // context. This can be fixed similarly to how these flags are handled for |
| 3449 | // adds. |
| 3450 | SCEV::NoWrapFlags OffsetWrap = |
| 3451 | GEP->isInBounds() ? SCEV::FlagNSW : SCEV::FlagAnyWrap; |
| 3452 | |
| 3453 | Type *CurTy = GEP->getType(); |
| 3454 | bool FirstIter = true; |
| 3455 | SmallVector<const SCEV *, 4> Offsets; |
| 3456 | for (const SCEV *IndexExpr : IndexExprs) { |
| 3457 | // Compute the (potentially symbolic) offset in bytes for this index. |
| 3458 | if (StructType *STy = dyn_cast<StructType>(CurTy)) { |
| 3459 | // For a struct, add the member offset. |
| 3460 | ConstantInt *Index = cast<SCEVConstant>(IndexExpr)->getValue(); |
| 3461 | unsigned FieldNo = Index->getZExtValue(); |
| 3462 | const SCEV *FieldOffset = getOffsetOfExpr(IntIdxTy, STy, FieldNo); |
| 3463 | Offsets.push_back(FieldOffset); |
| 3464 | |
| 3465 | // Update CurTy to the type of the field at Index. |
| 3466 | CurTy = STy->getTypeAtIndex(Index); |
| 3467 | } else { |
| 3468 | // Update CurTy to its element type. |
| 3469 | if (FirstIter) { |
| 3470 | assert(isa<PointerType>(CurTy) &&(static_cast <bool> (isa<PointerType>(CurTy) && "The first index of a GEP indexes a pointer") ? void (0) : __assert_fail ("isa<PointerType>(CurTy) && \"The first index of a GEP indexes a pointer\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 3471, __extension__ __PRETTY_FUNCTION__)) |
| 3471 | "The first index of a GEP indexes a pointer")(static_cast <bool> (isa<PointerType>(CurTy) && "The first index of a GEP indexes a pointer") ? void (0) : __assert_fail ("isa<PointerType>(CurTy) && \"The first index of a GEP indexes a pointer\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 3471, __extension__ __PRETTY_FUNCTION__)); |
| 3472 | CurTy = GEP->getSourceElementType(); |
| 3473 | FirstIter = false; |
| 3474 | } else { |
| 3475 | CurTy = GetElementPtrInst::getTypeAtIndex(CurTy, (uint64_t)0); |
| 3476 | } |
| 3477 | // For an array, add the element offset, explicitly scaled. |
| 3478 | const SCEV *ElementSize = getSizeOfExpr(IntIdxTy, CurTy); |
| 3479 | // Getelementptr indices are signed. |
| 3480 | IndexExpr = getTruncateOrSignExtend(IndexExpr, IntIdxTy); |
| 3481 | |
| 3482 | // Multiply the index by the element size to compute the element offset. |
| 3483 | const SCEV *LocalOffset = getMulExpr(IndexExpr, ElementSize, OffsetWrap); |
| 3484 | Offsets.push_back(LocalOffset); |
| 3485 | } |
| 3486 | } |
| 3487 | |
| 3488 | // Handle degenerate case of GEP without offsets. |
| 3489 | if (Offsets.empty()) |
| 3490 | return BaseExpr; |
| 3491 | |
| 3492 | // Add the offsets together, assuming nsw if inbounds. |
| 3493 | const SCEV *Offset = getAddExpr(Offsets, OffsetWrap); |
| 3494 | // Add the base address and the offset. We cannot use the nsw flag, as the |
| 3495 | // base address is unsigned. However, if we know that the offset is |
| 3496 | // non-negative, we can use nuw. |
| 3497 | SCEV::NoWrapFlags BaseWrap = GEP->isInBounds() && isKnownNonNegative(Offset) |
| 3498 | ? SCEV::FlagNUW : SCEV::FlagAnyWrap; |
| 3499 | return getAddExpr(BaseExpr, Offset, BaseWrap); |
| 3500 | } |
| 3501 | |
| 3502 | std::tuple<SCEV *, FoldingSetNodeID, void *> |
| 3503 | ScalarEvolution::findExistingSCEVInCache(SCEVTypes SCEVType, |
| 3504 | ArrayRef<const SCEV *> Ops) { |
| 3505 | FoldingSetNodeID ID; |
| 3506 | void *IP = nullptr; |
| 3507 | ID.AddInteger(SCEVType); |
| 3508 | for (unsigned i = 0, e = Ops.size(); i != e; ++i) |
| 3509 | ID.AddPointer(Ops[i]); |
| 3510 | return std::tuple<SCEV *, FoldingSetNodeID, void *>( |
| 3511 | UniqueSCEVs.FindNodeOrInsertPos(ID, IP), std::move(ID), IP); |
| 3512 | } |
| 3513 | |
| 3514 | const SCEV *ScalarEvolution::getAbsExpr(const SCEV *Op, bool IsNSW) { |
| 3515 | SCEV::NoWrapFlags Flags = IsNSW ? SCEV::FlagNSW : SCEV::FlagAnyWrap; |
| 3516 | return getSMaxExpr(Op, getNegativeSCEV(Op, Flags)); |
| 3517 | } |
| 3518 | |
| 3519 | const SCEV *ScalarEvolution::getMinMaxExpr(SCEVTypes Kind, |
| 3520 | SmallVectorImpl<const SCEV *> &Ops) { |
| 3521 | assert(!Ops.empty() && "Cannot get empty (u|s)(min|max)!")(static_cast <bool> (!Ops.empty() && "Cannot get empty (u|s)(min|max)!" ) ? void (0) : __assert_fail ("!Ops.empty() && \"Cannot get empty (u|s)(min|max)!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 3521, __extension__ __PRETTY_FUNCTION__)); |
| 3522 | if (Ops.size() == 1) return Ops[0]; |
| 3523 | #ifndef NDEBUG |
| 3524 | Type *ETy = getEffectiveSCEVType(Ops[0]->getType()); |
| 3525 | for (unsigned i = 1, e = Ops.size(); i != e; ++i) |
| 3526 | assert(getEffectiveSCEVType(Ops[i]->getType()) == ETy &&(static_cast <bool> (getEffectiveSCEVType(Ops[i]->getType ()) == ETy && "Operand types don't match!") ? void (0 ) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"Operand types don't match!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 3527, __extension__ __PRETTY_FUNCTION__)) |
| 3527 | "Operand types don't match!")(static_cast <bool> (getEffectiveSCEVType(Ops[i]->getType ()) == ETy && "Operand types don't match!") ? void (0 ) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"Operand types don't match!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 3527, __extension__ __PRETTY_FUNCTION__)); |
| 3528 | #endif |
| 3529 | |
| 3530 | bool IsSigned = Kind == scSMaxExpr || Kind == scSMinExpr; |
| 3531 | bool IsMax = Kind == scSMaxExpr || Kind == scUMaxExpr; |
| 3532 | |
| 3533 | // Sort by complexity, this groups all similar expression types together. |
| 3534 | GroupByComplexity(Ops, &LI, DT); |
| 3535 | |
| 3536 | // Check if we have created the same expression before. |
| 3537 | if (const SCEV *S = std::get<0>(findExistingSCEVInCache(Kind, Ops))) { |
| 3538 | return S; |
| 3539 | } |
| 3540 | |
| 3541 | // If there are any constants, fold them together. |
| 3542 | unsigned Idx = 0; |
| 3543 | if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) { |
| 3544 | ++Idx; |
| 3545 | assert(Idx < Ops.size())(static_cast <bool> (Idx < Ops.size()) ? void (0) : __assert_fail ("Idx < Ops.size()", "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 3545, __extension__ __PRETTY_FUNCTION__)); |
| 3546 | auto FoldOp = [&](const APInt &LHS, const APInt &RHS) { |
| 3547 | if (Kind == scSMaxExpr) |
| 3548 | return APIntOps::smax(LHS, RHS); |
| 3549 | else if (Kind == scSMinExpr) |
| 3550 | return APIntOps::smin(LHS, RHS); |
| 3551 | else if (Kind == scUMaxExpr) |
| 3552 | return APIntOps::umax(LHS, RHS); |
| 3553 | else if (Kind == scUMinExpr) |
| 3554 | return APIntOps::umin(LHS, RHS); |
| 3555 | llvm_unreachable("Unknown SCEV min/max opcode")::llvm::llvm_unreachable_internal("Unknown SCEV min/max opcode" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 3555); |
| 3556 | }; |
| 3557 | |
| 3558 | while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) { |
| 3559 | // We found two constants, fold them together! |
| 3560 | ConstantInt *Fold = ConstantInt::get( |
| 3561 | getContext(), FoldOp(LHSC->getAPInt(), RHSC->getAPInt())); |
| 3562 | Ops[0] = getConstant(Fold); |
| 3563 | Ops.erase(Ops.begin()+1); // Erase the folded element |
| 3564 | if (Ops.size() == 1) return Ops[0]; |
| 3565 | LHSC = cast<SCEVConstant>(Ops[0]); |
| 3566 | } |
| 3567 | |
| 3568 | bool IsMinV = LHSC->getValue()->isMinValue(IsSigned); |
| 3569 | bool IsMaxV = LHSC->getValue()->isMaxValue(IsSigned); |
| 3570 | |
| 3571 | if (IsMax ? IsMinV : IsMaxV) { |
| 3572 | // If we are left with a constant minimum(/maximum)-int, strip it off. |
| 3573 | Ops.erase(Ops.begin()); |
| 3574 | --Idx; |
| 3575 | } else if (IsMax ? IsMaxV : IsMinV) { |
| 3576 | // If we have a max(/min) with a constant maximum(/minimum)-int, |
| 3577 | // it will always be the extremum. |
| 3578 | return LHSC; |
| 3579 | } |
| 3580 | |
| 3581 | if (Ops.size() == 1) return Ops[0]; |
| 3582 | } |
| 3583 | |
| 3584 | // Find the first operation of the same kind |
| 3585 | while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < Kind) |
| 3586 | ++Idx; |
| 3587 | |
| 3588 | // Check to see if one of the operands is of the same kind. If so, expand its |
| 3589 | // operands onto our operand list, and recurse to simplify. |
| 3590 | if (Idx < Ops.size()) { |
| 3591 | bool DeletedAny = false; |
| 3592 | while (Ops[Idx]->getSCEVType() == Kind) { |
| 3593 | const SCEVMinMaxExpr *SMME = cast<SCEVMinMaxExpr>(Ops[Idx]); |
| 3594 | Ops.erase(Ops.begin()+Idx); |
| 3595 | Ops.append(SMME->op_begin(), SMME->op_end()); |
| 3596 | DeletedAny = true; |
| 3597 | } |
| 3598 | |
| 3599 | if (DeletedAny) |
| 3600 | return getMinMaxExpr(Kind, Ops); |
| 3601 | } |
| 3602 | |
| 3603 | // Okay, check to see if the same value occurs in the operand list twice. If |
| 3604 | // so, delete one. Since we sorted the list, these values are required to |
| 3605 | // be adjacent. |
| 3606 | llvm::CmpInst::Predicate GEPred = |
| 3607 | IsSigned ? ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE; |
| 3608 | llvm::CmpInst::Predicate LEPred = |
| 3609 | IsSigned ? ICmpInst::ICMP_SLE : ICmpInst::ICMP_ULE; |
| 3610 | llvm::CmpInst::Predicate FirstPred = IsMax ? GEPred : LEPred; |
| 3611 | llvm::CmpInst::Predicate SecondPred = IsMax ? LEPred : GEPred; |
| 3612 | for (unsigned i = 0, e = Ops.size() - 1; i != e; ++i) { |
| 3613 | if (Ops[i] == Ops[i + 1] || |
| 3614 | isKnownViaNonRecursiveReasoning(FirstPred, Ops[i], Ops[i + 1])) { |
| 3615 | // X op Y op Y --> X op Y |
| 3616 | // X op Y --> X, if we know X, Y are ordered appropriately |
| 3617 | Ops.erase(Ops.begin() + i + 1, Ops.begin() + i + 2); |
| 3618 | --i; |
| 3619 | --e; |
| 3620 | } else if (isKnownViaNonRecursiveReasoning(SecondPred, Ops[i], |
| 3621 | Ops[i + 1])) { |
| 3622 | // X op Y --> Y, if we know X, Y are ordered appropriately |
| 3623 | Ops.erase(Ops.begin() + i, Ops.begin() + i + 1); |
| 3624 | --i; |
| 3625 | --e; |
| 3626 | } |
| 3627 | } |
| 3628 | |
| 3629 | if (Ops.size() == 1) return Ops[0]; |
| 3630 | |
| 3631 | assert(!Ops.empty() && "Reduced smax down to nothing!")(static_cast <bool> (!Ops.empty() && "Reduced smax down to nothing!" ) ? void (0) : __assert_fail ("!Ops.empty() && \"Reduced smax down to nothing!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 3631, __extension__ __PRETTY_FUNCTION__)); |
| 3632 | |
| 3633 | // Okay, it looks like we really DO need an expr. Check to see if we |
| 3634 | // already have one, otherwise create a new one. |
| 3635 | const SCEV *ExistingSCEV; |
| 3636 | FoldingSetNodeID ID; |
| 3637 | void *IP; |
| 3638 | std::tie(ExistingSCEV, ID, IP) = findExistingSCEVInCache(Kind, Ops); |
| 3639 | if (ExistingSCEV) |
| 3640 | return ExistingSCEV; |
| 3641 | const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size()); |
| 3642 | std::uninitialized_copy(Ops.begin(), Ops.end(), O); |
| 3643 | SCEV *S = new (SCEVAllocator) |
| 3644 | SCEVMinMaxExpr(ID.Intern(SCEVAllocator), Kind, O, Ops.size()); |
| 3645 | |
| 3646 | UniqueSCEVs.InsertNode(S, IP); |
| 3647 | addToLoopUseLists(S); |
| 3648 | return S; |
| 3649 | } |
| 3650 | |
| 3651 | const SCEV *ScalarEvolution::getSMaxExpr(const SCEV *LHS, const SCEV *RHS) { |
| 3652 | SmallVector<const SCEV *, 2> Ops = {LHS, RHS}; |
| 3653 | return getSMaxExpr(Ops); |
| 3654 | } |
| 3655 | |
| 3656 | const SCEV *ScalarEvolution::getSMaxExpr(SmallVectorImpl<const SCEV *> &Ops) { |
| 3657 | return getMinMaxExpr(scSMaxExpr, Ops); |
| 3658 | } |
| 3659 | |
| 3660 | const SCEV *ScalarEvolution::getUMaxExpr(const SCEV *LHS, const SCEV *RHS) { |
| 3661 | SmallVector<const SCEV *, 2> Ops = {LHS, RHS}; |
| 3662 | return getUMaxExpr(Ops); |
| 3663 | } |
| 3664 | |
| 3665 | const SCEV *ScalarEvolution::getUMaxExpr(SmallVectorImpl<const SCEV *> &Ops) { |
| 3666 | return getMinMaxExpr(scUMaxExpr, Ops); |
| 3667 | } |
| 3668 | |
| 3669 | const SCEV *ScalarEvolution::getSMinExpr(const SCEV *LHS, |
| 3670 | const SCEV *RHS) { |
| 3671 | SmallVector<const SCEV *, 2> Ops = { LHS, RHS }; |
| 3672 | return getSMinExpr(Ops); |
| 3673 | } |
| 3674 | |
| 3675 | const SCEV *ScalarEvolution::getSMinExpr(SmallVectorImpl<const SCEV *> &Ops) { |
| 3676 | return getMinMaxExpr(scSMinExpr, Ops); |
| 3677 | } |
| 3678 | |
| 3679 | const SCEV *ScalarEvolution::getUMinExpr(const SCEV *LHS, |
| 3680 | const SCEV *RHS) { |
| 3681 | SmallVector<const SCEV *, 2> Ops = { LHS, RHS }; |
| 3682 | return getUMinExpr(Ops); |
| 3683 | } |
| 3684 | |
| 3685 | const SCEV *ScalarEvolution::getUMinExpr(SmallVectorImpl<const SCEV *> &Ops) { |
| 3686 | return getMinMaxExpr(scUMinExpr, Ops); |
| 3687 | } |
| 3688 | |
| 3689 | const SCEV * |
| 3690 | ScalarEvolution::getSizeOfScalableVectorExpr(Type *IntTy, |
| 3691 | ScalableVectorType *ScalableTy) { |
| 3692 | Constant *NullPtr = Constant::getNullValue(ScalableTy->getPointerTo()); |
| 3693 | Constant *One = ConstantInt::get(IntTy, 1); |
| 3694 | Constant *GEP = ConstantExpr::getGetElementPtr(ScalableTy, NullPtr, One); |
| 3695 | // Note that the expression we created is the final expression, we don't |
| 3696 | // want to simplify it any further Also, if we call a normal getSCEV(), |
| 3697 | // we'll end up in an endless recursion. So just create an SCEVUnknown. |
| 3698 | return getUnknown(ConstantExpr::getPtrToInt(GEP, IntTy)); |
| 3699 | } |
| 3700 | |
| 3701 | const SCEV *ScalarEvolution::getSizeOfExpr(Type *IntTy, Type *AllocTy) { |
| 3702 | if (auto *ScalableAllocTy = dyn_cast<ScalableVectorType>(AllocTy)) |
| 3703 | return getSizeOfScalableVectorExpr(IntTy, ScalableAllocTy); |
| 3704 | // We can bypass creating a target-independent constant expression and then |
| 3705 | // folding it back into a ConstantInt. This is just a compile-time |
| 3706 | // optimization. |
| 3707 | return getConstant(IntTy, getDataLayout().getTypeAllocSize(AllocTy)); |
| 3708 | } |
| 3709 | |
| 3710 | const SCEV *ScalarEvolution::getStoreSizeOfExpr(Type *IntTy, Type *StoreTy) { |
| 3711 | if (auto *ScalableStoreTy = dyn_cast<ScalableVectorType>(StoreTy)) |
| 3712 | return getSizeOfScalableVectorExpr(IntTy, ScalableStoreTy); |
| 3713 | // We can bypass creating a target-independent constant expression and then |
| 3714 | // folding it back into a ConstantInt. This is just a compile-time |
| 3715 | // optimization. |
| 3716 | return getConstant(IntTy, getDataLayout().getTypeStoreSize(StoreTy)); |
| 3717 | } |
| 3718 | |
| 3719 | const SCEV *ScalarEvolution::getOffsetOfExpr(Type *IntTy, |
| 3720 | StructType *STy, |
| 3721 | unsigned FieldNo) { |
| 3722 | // We can bypass creating a target-independent constant expression and then |
| 3723 | // folding it back into a ConstantInt. This is just a compile-time |
| 3724 | // optimization. |
| 3725 | return getConstant( |
| 3726 | IntTy, getDataLayout().getStructLayout(STy)->getElementOffset(FieldNo)); |
| 3727 | } |
| 3728 | |
| 3729 | const SCEV *ScalarEvolution::getUnknown(Value *V) { |
| 3730 | // Don't attempt to do anything other than create a SCEVUnknown object |
| 3731 | // here. createSCEV only calls getUnknown after checking for all other |
| 3732 | // interesting possibilities, and any other code that calls getUnknown |
| 3733 | // is doing so in order to hide a value from SCEV canonicalization. |
| 3734 | |
| 3735 | FoldingSetNodeID ID; |
| 3736 | ID.AddInteger(scUnknown); |
| 3737 | ID.AddPointer(V); |
| 3738 | void *IP = nullptr; |
| 3739 | if (SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) { |
| 3740 | assert(cast<SCEVUnknown>(S)->getValue() == V &&(static_cast <bool> (cast<SCEVUnknown>(S)->getValue () == V && "Stale SCEVUnknown in uniquing map!") ? void (0) : __assert_fail ("cast<SCEVUnknown>(S)->getValue() == V && \"Stale SCEVUnknown in uniquing map!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 3741, __extension__ __PRETTY_FUNCTION__)) |
| 3741 | "Stale SCEVUnknown in uniquing map!")(static_cast <bool> (cast<SCEVUnknown>(S)->getValue () == V && "Stale SCEVUnknown in uniquing map!") ? void (0) : __assert_fail ("cast<SCEVUnknown>(S)->getValue() == V && \"Stale SCEVUnknown in uniquing map!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 3741, __extension__ __PRETTY_FUNCTION__)); |
| 3742 | return S; |
| 3743 | } |
| 3744 | SCEV *S = new (SCEVAllocator) SCEVUnknown(ID.Intern(SCEVAllocator), V, this, |
| 3745 | FirstUnknown); |
| 3746 | FirstUnknown = cast<SCEVUnknown>(S); |
| 3747 | UniqueSCEVs.InsertNode(S, IP); |
| 3748 | return S; |
| 3749 | } |
| 3750 | |
| 3751 | //===----------------------------------------------------------------------===// |
| 3752 | // Basic SCEV Analysis and PHI Idiom Recognition Code |
| 3753 | // |
| 3754 | |
| 3755 | /// Test if values of the given type are analyzable within the SCEV |
| 3756 | /// framework. This primarily includes integer types, and it can optionally |
| 3757 | /// include pointer types if the ScalarEvolution class has access to |
| 3758 | /// target-specific information. |
| 3759 | bool ScalarEvolution::isSCEVable(Type *Ty) const { |
| 3760 | // Integers and pointers are always SCEVable. |
| 3761 | return Ty->isIntOrPtrTy(); |
| 3762 | } |
| 3763 | |
| 3764 | /// Return the size in bits of the specified type, for which isSCEVable must |
| 3765 | /// return true. |
| 3766 | uint64_t ScalarEvolution::getTypeSizeInBits(Type *Ty) const { |
| 3767 | assert(isSCEVable(Ty) && "Type is not SCEVable!")(static_cast <bool> (isSCEVable(Ty) && "Type is not SCEVable!" ) ? void (0) : __assert_fail ("isSCEVable(Ty) && \"Type is not SCEVable!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 3767, __extension__ __PRETTY_FUNCTION__)); |
| 3768 | if (Ty->isPointerTy()) |
| 3769 | return getDataLayout().getIndexTypeSizeInBits(Ty); |
| 3770 | return getDataLayout().getTypeSizeInBits(Ty); |
| 3771 | } |
| 3772 | |
| 3773 | /// Return a type with the same bitwidth as the given type and which represents |
| 3774 | /// how SCEV will treat the given type, for which isSCEVable must return |
| 3775 | /// true. For pointer types, this is the pointer index sized integer type. |
| 3776 | Type *ScalarEvolution::getEffectiveSCEVType(Type *Ty) const { |
| 3777 | assert(isSCEVable(Ty) && "Type is not SCEVable!")(static_cast <bool> (isSCEVable(Ty) && "Type is not SCEVable!" ) ? void (0) : __assert_fail ("isSCEVable(Ty) && \"Type is not SCEVable!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 3777, __extension__ __PRETTY_FUNCTION__)); |
| 3778 | |
| 3779 | if (Ty->isIntegerTy()) |
| 3780 | return Ty; |
| 3781 | |
| 3782 | // The only other support type is pointer. |
| 3783 | assert(Ty->isPointerTy() && "Unexpected non-pointer non-integer type!")(static_cast <bool> (Ty->isPointerTy() && "Unexpected non-pointer non-integer type!" ) ? void (0) : __assert_fail ("Ty->isPointerTy() && \"Unexpected non-pointer non-integer type!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 3783, __extension__ __PRETTY_FUNCTION__)); |
| 3784 | return getDataLayout().getIndexType(Ty); |
| 3785 | } |
| 3786 | |
| 3787 | Type *ScalarEvolution::getWiderType(Type *T1, Type *T2) const { |
| 3788 | return getTypeSizeInBits(T1) >= getTypeSizeInBits(T2) ? T1 : T2; |
| 3789 | } |
| 3790 | |
| 3791 | const SCEV *ScalarEvolution::getCouldNotCompute() { |
| 3792 | return CouldNotCompute.get(); |
| 3793 | } |
| 3794 | |
| 3795 | bool ScalarEvolution::checkValidity(const SCEV *S) const { |
| 3796 | bool ContainsNulls = SCEVExprContains(S, [](const SCEV *S) { |
| 3797 | auto *SU = dyn_cast<SCEVUnknown>(S); |
| 3798 | return SU && SU->getValue() == nullptr; |
| 3799 | }); |
| 3800 | |
| 3801 | return !ContainsNulls; |
| 3802 | } |
| 3803 | |
| 3804 | bool ScalarEvolution::containsAddRecurrence(const SCEV *S) { |
| 3805 | HasRecMapType::iterator I = HasRecMap.find(S); |
| 3806 | if (I != HasRecMap.end()) |
| 3807 | return I->second; |
| 3808 | |
| 3809 | bool FoundAddRec = |
| 3810 | SCEVExprContains(S, [](const SCEV *S) { return isa<SCEVAddRecExpr>(S); }); |
| 3811 | HasRecMap.insert({S, FoundAddRec}); |
| 3812 | return FoundAddRec; |
| 3813 | } |
| 3814 | |
| 3815 | /// Try to split a SCEVAddExpr into a pair of {SCEV, ConstantInt}. |
| 3816 | /// If \p S is a SCEVAddExpr and is composed of a sub SCEV S' and an |
| 3817 | /// offset I, then return {S', I}, else return {\p S, nullptr}. |
| 3818 | static std::pair<const SCEV *, ConstantInt *> splitAddExpr(const SCEV *S) { |
| 3819 | const auto *Add = dyn_cast<SCEVAddExpr>(S); |
| 3820 | if (!Add) |
| 3821 | return {S, nullptr}; |
| 3822 | |
| 3823 | if (Add->getNumOperands() != 2) |
| 3824 | return {S, nullptr}; |
| 3825 | |
| 3826 | auto *ConstOp = dyn_cast<SCEVConstant>(Add->getOperand(0)); |
| 3827 | if (!ConstOp) |
| 3828 | return {S, nullptr}; |
| 3829 | |
| 3830 | return {Add->getOperand(1), ConstOp->getValue()}; |
| 3831 | } |
| 3832 | |
| 3833 | /// Return the ValueOffsetPair set for \p S. \p S can be represented |
| 3834 | /// by the value and offset from any ValueOffsetPair in the set. |
| 3835 | SetVector<ScalarEvolution::ValueOffsetPair> * |
| 3836 | ScalarEvolution::getSCEVValues(const SCEV *S) { |
| 3837 | ExprValueMapType::iterator SI = ExprValueMap.find_as(S); |
| 3838 | if (SI == ExprValueMap.end()) |
| 3839 | return nullptr; |
| 3840 | #ifndef NDEBUG |
| 3841 | if (VerifySCEVMap) { |
| 3842 | // Check there is no dangling Value in the set returned. |
| 3843 | for (const auto &VE : SI->second) |
| 3844 | assert(ValueExprMap.count(VE.first))(static_cast <bool> (ValueExprMap.count(VE.first)) ? void (0) : __assert_fail ("ValueExprMap.count(VE.first)", "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 3844, __extension__ __PRETTY_FUNCTION__)); |
| 3845 | } |
| 3846 | #endif |
| 3847 | return &SI->second; |
| 3848 | } |
| 3849 | |
| 3850 | /// Erase Value from ValueExprMap and ExprValueMap. ValueExprMap.erase(V) |
| 3851 | /// cannot be used separately. eraseValueFromMap should be used to remove |
| 3852 | /// V from ValueExprMap and ExprValueMap at the same time. |
| 3853 | void ScalarEvolution::eraseValueFromMap(Value *V) { |
| 3854 | ValueExprMapType::iterator I = ValueExprMap.find_as(V); |
| 3855 | if (I != ValueExprMap.end()) { |
| 3856 | const SCEV *S = I->second; |
| 3857 | // Remove {V, 0} from the set of ExprValueMap[S] |
| 3858 | if (SetVector<ValueOffsetPair> *SV = getSCEVValues(S)) |
| 3859 | SV->remove({V, nullptr}); |
| 3860 | |
| 3861 | // Remove {V, Offset} from the set of ExprValueMap[Stripped] |
| 3862 | const SCEV *Stripped; |
| 3863 | ConstantInt *Offset; |
| 3864 | std::tie(Stripped, Offset) = splitAddExpr(S); |
| 3865 | if (Offset != nullptr) { |
| 3866 | if (SetVector<ValueOffsetPair> *SV = getSCEVValues(Stripped)) |
| 3867 | SV->remove({V, Offset}); |
| 3868 | } |
| 3869 | ValueExprMap.erase(V); |
| 3870 | } |
| 3871 | } |
| 3872 | |
| 3873 | /// Check whether value has nuw/nsw/exact set but SCEV does not. |
| 3874 | /// TODO: In reality it is better to check the poison recursively |
| 3875 | /// but this is better than nothing. |
| 3876 | static bool SCEVLostPoisonFlags(const SCEV *S, const Value *V) { |
| 3877 | if (auto *I = dyn_cast<Instruction>(V)) { |
| 3878 | if (isa<OverflowingBinaryOperator>(I)) { |
| 3879 | if (auto *NS = dyn_cast<SCEVNAryExpr>(S)) { |
| 3880 | if (I->hasNoSignedWrap() && !NS->hasNoSignedWrap()) |
| 3881 | return true; |
| 3882 | if (I->hasNoUnsignedWrap() && !NS->hasNoUnsignedWrap()) |
| 3883 | return true; |
| 3884 | } |
| 3885 | } else if (isa<PossiblyExactOperator>(I) && I->isExact()) |
| 3886 | return true; |
| 3887 | } |
| 3888 | return false; |
| 3889 | } |
| 3890 | |
| 3891 | /// Return an existing SCEV if it exists, otherwise analyze the expression and |
| 3892 | /// create a new one. |
| 3893 | const SCEV *ScalarEvolution::getSCEV(Value *V) { |
| 3894 | assert(isSCEVable(V->getType()) && "Value is not SCEVable!")(static_cast <bool> (isSCEVable(V->getType()) && "Value is not SCEVable!") ? void (0) : __assert_fail ("isSCEVable(V->getType()) && \"Value is not SCEVable!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 3894, __extension__ __PRETTY_FUNCTION__)); |
| 3895 | |
| 3896 | const SCEV *S = getExistingSCEV(V); |
| 3897 | if (S == nullptr) { |
| 3898 | S = createSCEV(V); |
| 3899 | // During PHI resolution, it is possible to create two SCEVs for the same |
| 3900 | // V, so it is needed to double check whether V->S is inserted into |
| 3901 | // ValueExprMap before insert S->{V, 0} into ExprValueMap. |
| 3902 | std::pair<ValueExprMapType::iterator, bool> Pair = |
| 3903 | ValueExprMap.insert({SCEVCallbackVH(V, this), S}); |
| 3904 | if (Pair.second && !SCEVLostPoisonFlags(S, V)) { |
| 3905 | ExprValueMap[S].insert({V, nullptr}); |
| 3906 | |
| 3907 | // If S == Stripped + Offset, add Stripped -> {V, Offset} into |
| 3908 | // ExprValueMap. |
| 3909 | const SCEV *Stripped = S; |
| 3910 | ConstantInt *Offset = nullptr; |
| 3911 | std::tie(Stripped, Offset) = splitAddExpr(S); |
| 3912 | // If stripped is SCEVUnknown, don't bother to save |
| 3913 | // Stripped -> {V, offset}. It doesn't simplify and sometimes even |
| 3914 | // increase the complexity of the expansion code. |
| 3915 | // If V is GetElementPtrInst, don't save Stripped -> {V, offset} |
| 3916 | // because it may generate add/sub instead of GEP in SCEV expansion. |
| 3917 | if (Offset != nullptr && !isa<SCEVUnknown>(Stripped) && |
| 3918 | !isa<GetElementPtrInst>(V)) |
| 3919 | ExprValueMap[Stripped].insert({V, Offset}); |
| 3920 | } |
| 3921 | } |
| 3922 | return S; |
| 3923 | } |
| 3924 | |
| 3925 | const SCEV *ScalarEvolution::getExistingSCEV(Value *V) { |
| 3926 | assert(isSCEVable(V->getType()) && "Value is not SCEVable!")(static_cast <bool> (isSCEVable(V->getType()) && "Value is not SCEVable!") ? void (0) : __assert_fail ("isSCEVable(V->getType()) && \"Value is not SCEVable!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 3926, __extension__ __PRETTY_FUNCTION__)); |
| 3927 | |
| 3928 | ValueExprMapType::iterator I = ValueExprMap.find_as(V); |
| 3929 | if (I != ValueExprMap.end()) { |
| 3930 | const SCEV *S = I->second; |
| 3931 | if (checkValidity(S)) |
| 3932 | return S; |
| 3933 | eraseValueFromMap(V); |
| 3934 | forgetMemoizedResults(S); |
| 3935 | } |
| 3936 | return nullptr; |
| 3937 | } |
| 3938 | |
| 3939 | /// Return a SCEV corresponding to -V = -1*V |
| 3940 | const SCEV *ScalarEvolution::getNegativeSCEV(const SCEV *V, |
| 3941 | SCEV::NoWrapFlags Flags) { |
| 3942 | if (const SCEVConstant *VC = dyn_cast<SCEVConstant>(V)) |
| 3943 | return getConstant( |
| 3944 | cast<ConstantInt>(ConstantExpr::getNeg(VC->getValue()))); |
| 3945 | |
| 3946 | Type *Ty = V->getType(); |
| 3947 | Ty = getEffectiveSCEVType(Ty); |
| 3948 | return getMulExpr(V, getMinusOne(Ty), Flags); |
| 3949 | } |
| 3950 | |
| 3951 | /// If Expr computes ~A, return A else return nullptr |
| 3952 | static const SCEV *MatchNotExpr(const SCEV *Expr) { |
| 3953 | const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Expr); |
| 3954 | if (!Add || Add->getNumOperands() != 2 || |
| 3955 | !Add->getOperand(0)->isAllOnesValue()) |
| 3956 | return nullptr; |
| 3957 | |
| 3958 | const SCEVMulExpr *AddRHS = dyn_cast<SCEVMulExpr>(Add->getOperand(1)); |
| 3959 | if (!AddRHS || AddRHS->getNumOperands() != 2 || |
| 3960 | !AddRHS->getOperand(0)->isAllOnesValue()) |
| 3961 | return nullptr; |
| 3962 | |
| 3963 | return AddRHS->getOperand(1); |
| 3964 | } |
| 3965 | |
| 3966 | /// Return a SCEV corresponding to ~V = -1-V |
| 3967 | const SCEV *ScalarEvolution::getNotSCEV(const SCEV *V) { |
| 3968 | if (const SCEVConstant *VC = dyn_cast<SCEVConstant>(V)) |
| 3969 | return getConstant( |
| 3970 | cast<ConstantInt>(ConstantExpr::getNot(VC->getValue()))); |
| 3971 | |
| 3972 | // Fold ~(u|s)(min|max)(~x, ~y) to (u|s)(max|min)(x, y) |
| 3973 | if (const SCEVMinMaxExpr *MME = dyn_cast<SCEVMinMaxExpr>(V)) { |
| 3974 | auto MatchMinMaxNegation = [&](const SCEVMinMaxExpr *MME) { |
| 3975 | SmallVector<const SCEV *, 2> MatchedOperands; |
| 3976 | for (const SCEV *Operand : MME->operands()) { |
| 3977 | const SCEV *Matched = MatchNotExpr(Operand); |
| 3978 | if (!Matched) |
| 3979 | return (const SCEV *)nullptr; |
| 3980 | MatchedOperands.push_back(Matched); |
| 3981 | } |
| 3982 | return getMinMaxExpr(SCEVMinMaxExpr::negate(MME->getSCEVType()), |
| 3983 | MatchedOperands); |
| 3984 | }; |
| 3985 | if (const SCEV *Replaced = MatchMinMaxNegation(MME)) |
| 3986 | return Replaced; |
| 3987 | } |
| 3988 | |
| 3989 | Type *Ty = V->getType(); |
| 3990 | Ty = getEffectiveSCEVType(Ty); |
| 3991 | return getMinusSCEV(getMinusOne(Ty), V); |
| 3992 | } |
| 3993 | |
| 3994 | const SCEV *ScalarEvolution::getMinusSCEV(const SCEV *LHS, const SCEV *RHS, |
| 3995 | SCEV::NoWrapFlags Flags, |
| 3996 | unsigned Depth) { |
| 3997 | // Fast path: X - X --> 0. |
| 3998 | if (LHS == RHS) |
| 3999 | return getZero(LHS->getType()); |
| 4000 | |
| 4001 | // We represent LHS - RHS as LHS + (-1)*RHS. This transformation |
| 4002 | // makes it so that we cannot make much use of NUW. |
| 4003 | auto AddFlags = SCEV::FlagAnyWrap; |
| 4004 | const bool RHSIsNotMinSigned = |
| 4005 | !getSignedRangeMin(RHS).isMinSignedValue(); |
| 4006 | if (maskFlags(Flags, SCEV::FlagNSW) == SCEV::FlagNSW) { |
| 4007 | // Let M be the minimum representable signed value. Then (-1)*RHS |
| 4008 | // signed-wraps if and only if RHS is M. That can happen even for |
| 4009 | // a NSW subtraction because e.g. (-1)*M signed-wraps even though |
| 4010 | // -1 - M does not. So to transfer NSW from LHS - RHS to LHS + |
| 4011 | // (-1)*RHS, we need to prove that RHS != M. |
| 4012 | // |
| 4013 | // If LHS is non-negative and we know that LHS - RHS does not |
| 4014 | // signed-wrap, then RHS cannot be M. So we can rule out signed-wrap |
| 4015 | // either by proving that RHS > M or that LHS >= 0. |
| 4016 | if (RHSIsNotMinSigned || isKnownNonNegative(LHS)) { |
| 4017 | AddFlags = SCEV::FlagNSW; |
| 4018 | } |
| 4019 | } |
| 4020 | |
| 4021 | // FIXME: Find a correct way to transfer NSW to (-1)*M when LHS - |
| 4022 | // RHS is NSW and LHS >= 0. |
| 4023 | // |
| 4024 | // The difficulty here is that the NSW flag may have been proven |
| 4025 | // relative to a loop that is to be found in a recurrence in LHS and |
| 4026 | // not in RHS. Applying NSW to (-1)*M may then let the NSW have a |
| 4027 | // larger scope than intended. |
| 4028 | auto NegFlags = RHSIsNotMinSigned ? SCEV::FlagNSW : SCEV::FlagAnyWrap; |
| 4029 | |
| 4030 | return getAddExpr(LHS, getNegativeSCEV(RHS, NegFlags), AddFlags, Depth); |
| 4031 | } |
| 4032 | |
| 4033 | const SCEV *ScalarEvolution::getTruncateOrZeroExtend(const SCEV *V, Type *Ty, |
| 4034 | unsigned Depth) { |
| 4035 | Type *SrcTy = V->getType(); |
| 4036 | assert(SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&(static_cast <bool> (SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && "Cannot truncate or zero extend with non-integer arguments!" ) ? void (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot truncate or zero extend with non-integer arguments!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 4037, __extension__ __PRETTY_FUNCTION__)) |
| 4037 | "Cannot truncate or zero extend with non-integer arguments!")(static_cast <bool> (SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && "Cannot truncate or zero extend with non-integer arguments!" ) ? void (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot truncate or zero extend with non-integer arguments!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 4037, __extension__ __PRETTY_FUNCTION__)); |
| 4038 | if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty)) |
| 4039 | return V; // No conversion |
| 4040 | if (getTypeSizeInBits(SrcTy) > getTypeSizeInBits(Ty)) |
| 4041 | return getTruncateExpr(V, Ty, Depth); |
| 4042 | return getZeroExtendExpr(V, Ty, Depth); |
| 4043 | } |
| 4044 | |
| 4045 | const SCEV *ScalarEvolution::getTruncateOrSignExtend(const SCEV *V, Type *Ty, |
| 4046 | unsigned Depth) { |
| 4047 | Type *SrcTy = V->getType(); |
| 4048 | assert(SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&(static_cast <bool> (SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && "Cannot truncate or zero extend with non-integer arguments!" ) ? void (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot truncate or zero extend with non-integer arguments!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 4049, __extension__ __PRETTY_FUNCTION__)) |
| 4049 | "Cannot truncate or zero extend with non-integer arguments!")(static_cast <bool> (SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && "Cannot truncate or zero extend with non-integer arguments!" ) ? void (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot truncate or zero extend with non-integer arguments!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 4049, __extension__ __PRETTY_FUNCTION__)); |
| 4050 | if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty)) |
| 4051 | return V; // No conversion |
| 4052 | if (getTypeSizeInBits(SrcTy) > getTypeSizeInBits(Ty)) |
| 4053 | return getTruncateExpr(V, Ty, Depth); |
| 4054 | return getSignExtendExpr(V, Ty, Depth); |
| 4055 | } |
| 4056 | |
| 4057 | const SCEV * |
| 4058 | ScalarEvolution::getNoopOrZeroExtend(const SCEV *V, Type *Ty) { |
| 4059 | Type *SrcTy = V->getType(); |
| 4060 | assert(SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&(static_cast <bool> (SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && "Cannot noop or zero extend with non-integer arguments!" ) ? void (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot noop or zero extend with non-integer arguments!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 4061, __extension__ __PRETTY_FUNCTION__)) |
| 4061 | "Cannot noop or zero extend with non-integer arguments!")(static_cast <bool> (SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && "Cannot noop or zero extend with non-integer arguments!" ) ? void (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot noop or zero extend with non-integer arguments!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 4061, __extension__ __PRETTY_FUNCTION__)); |
| 4062 | assert(getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) &&(static_cast <bool> (getTypeSizeInBits(SrcTy) <= getTypeSizeInBits (Ty) && "getNoopOrZeroExtend cannot truncate!") ? void (0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrZeroExtend cannot truncate!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 4063, __extension__ __PRETTY_FUNCTION__)) |
| 4063 | "getNoopOrZeroExtend cannot truncate!")(static_cast <bool> (getTypeSizeInBits(SrcTy) <= getTypeSizeInBits (Ty) && "getNoopOrZeroExtend cannot truncate!") ? void (0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrZeroExtend cannot truncate!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 4063, __extension__ __PRETTY_FUNCTION__)); |
| 4064 | if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty)) |
| 4065 | return V; // No conversion |
| 4066 | return getZeroExtendExpr(V, Ty); |
| 4067 | } |
| 4068 | |
| 4069 | const SCEV * |
| 4070 | ScalarEvolution::getNoopOrSignExtend(const SCEV *V, Type *Ty) { |
| 4071 | Type *SrcTy = V->getType(); |
| 4072 | assert(SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&(static_cast <bool> (SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && "Cannot noop or sign extend with non-integer arguments!" ) ? void (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot noop or sign extend with non-integer arguments!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 4073, __extension__ __PRETTY_FUNCTION__)) |
| 4073 | "Cannot noop or sign extend with non-integer arguments!")(static_cast <bool> (SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && "Cannot noop or sign extend with non-integer arguments!" ) ? void (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot noop or sign extend with non-integer arguments!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 4073, __extension__ __PRETTY_FUNCTION__)); |
| 4074 | assert(getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) &&(static_cast <bool> (getTypeSizeInBits(SrcTy) <= getTypeSizeInBits (Ty) && "getNoopOrSignExtend cannot truncate!") ? void (0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrSignExtend cannot truncate!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 4075, __extension__ __PRETTY_FUNCTION__)) |
| 4075 | "getNoopOrSignExtend cannot truncate!")(static_cast <bool> (getTypeSizeInBits(SrcTy) <= getTypeSizeInBits (Ty) && "getNoopOrSignExtend cannot truncate!") ? void (0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrSignExtend cannot truncate!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 4075, __extension__ __PRETTY_FUNCTION__)); |
| 4076 | if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty)) |
| 4077 | return V; // No conversion |
| 4078 | return getSignExtendExpr(V, Ty); |
| 4079 | } |
| 4080 | |
| 4081 | const SCEV * |
| 4082 | ScalarEvolution::getNoopOrAnyExtend(const SCEV *V, Type *Ty) { |
| 4083 | Type *SrcTy = V->getType(); |
| 4084 | assert(SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&(static_cast <bool> (SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && "Cannot noop or any extend with non-integer arguments!" ) ? void (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot noop or any extend with non-integer arguments!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 4085, __extension__ __PRETTY_FUNCTION__)) |
| 4085 | "Cannot noop or any extend with non-integer arguments!")(static_cast <bool> (SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && "Cannot noop or any extend with non-integer arguments!" ) ? void (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot noop or any extend with non-integer arguments!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 4085, __extension__ __PRETTY_FUNCTION__)); |
| 4086 | assert(getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) &&(static_cast <bool> (getTypeSizeInBits(SrcTy) <= getTypeSizeInBits (Ty) && "getNoopOrAnyExtend cannot truncate!") ? void (0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrAnyExtend cannot truncate!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 4087, __extension__ __PRETTY_FUNCTION__)) |
| 4087 | "getNoopOrAnyExtend cannot truncate!")(static_cast <bool> (getTypeSizeInBits(SrcTy) <= getTypeSizeInBits (Ty) && "getNoopOrAnyExtend cannot truncate!") ? void (0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrAnyExtend cannot truncate!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 4087, __extension__ __PRETTY_FUNCTION__)); |
| 4088 | if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty)) |
| 4089 | return V; // No conversion |
| 4090 | return getAnyExtendExpr(V, Ty); |
| 4091 | } |
| 4092 | |
| 4093 | const SCEV * |
| 4094 | ScalarEvolution::getTruncateOrNoop(const SCEV *V, Type *Ty) { |
| 4095 | Type *SrcTy = V->getType(); |
| 4096 | assert(SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&(static_cast <bool> (SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && "Cannot truncate or noop with non-integer arguments!" ) ? void (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot truncate or noop with non-integer arguments!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 4097, __extension__ __PRETTY_FUNCTION__)) |
| 4097 | "Cannot truncate or noop with non-integer arguments!")(static_cast <bool> (SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && "Cannot truncate or noop with non-integer arguments!" ) ? void (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot truncate or noop with non-integer arguments!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 4097, __extension__ __PRETTY_FUNCTION__)); |
| 4098 | assert(getTypeSizeInBits(SrcTy) >= getTypeSizeInBits(Ty) &&(static_cast <bool> (getTypeSizeInBits(SrcTy) >= getTypeSizeInBits (Ty) && "getTruncateOrNoop cannot extend!") ? void (0 ) : __assert_fail ("getTypeSizeInBits(SrcTy) >= getTypeSizeInBits(Ty) && \"getTruncateOrNoop cannot extend!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 4099, __extension__ __PRETTY_FUNCTION__)) |
| 4099 | "getTruncateOrNoop cannot extend!")(static_cast <bool> (getTypeSizeInBits(SrcTy) >= getTypeSizeInBits (Ty) && "getTruncateOrNoop cannot extend!") ? void (0 ) : __assert_fail ("getTypeSizeInBits(SrcTy) >= getTypeSizeInBits(Ty) && \"getTruncateOrNoop cannot extend!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 4099, __extension__ __PRETTY_FUNCTION__)); |
| 4100 | if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty)) |
| 4101 | return V; // No conversion |
| 4102 | return getTruncateExpr(V, Ty); |
| 4103 | } |
| 4104 | |
| 4105 | const SCEV *ScalarEvolution::getUMaxFromMismatchedTypes(const SCEV *LHS, |
| 4106 | const SCEV *RHS) { |
| 4107 | const SCEV *PromotedLHS = LHS; |
| 4108 | const SCEV *PromotedRHS = RHS; |
| 4109 | |
| 4110 | if (getTypeSizeInBits(LHS->getType()) > getTypeSizeInBits(RHS->getType())) |
| 4111 | PromotedRHS = getZeroExtendExpr(RHS, LHS->getType()); |
| 4112 | else |
| 4113 | PromotedLHS = getNoopOrZeroExtend(LHS, RHS->getType()); |
| 4114 | |
| 4115 | return getUMaxExpr(PromotedLHS, PromotedRHS); |
| 4116 | } |
| 4117 | |
| 4118 | const SCEV *ScalarEvolution::getUMinFromMismatchedTypes(const SCEV *LHS, |
| 4119 | const SCEV *RHS) { |
| 4120 | SmallVector<const SCEV *, 2> Ops = { LHS, RHS }; |
| 4121 | return getUMinFromMismatchedTypes(Ops); |
| 4122 | } |
| 4123 | |
| 4124 | const SCEV *ScalarEvolution::getUMinFromMismatchedTypes( |
| 4125 | SmallVectorImpl<const SCEV *> &Ops) { |
| 4126 | assert(!Ops.empty() && "At least one operand must be!")(static_cast <bool> (!Ops.empty() && "At least one operand must be!" ) ? void (0) : __assert_fail ("!Ops.empty() && \"At least one operand must be!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 4126, __extension__ __PRETTY_FUNCTION__)); |
| 4127 | // Trivial case. |
| 4128 | if (Ops.size() == 1) |
| 4129 | return Ops[0]; |
| 4130 | |
| 4131 | // Find the max type first. |
| 4132 | Type *MaxType = nullptr; |
| 4133 | for (auto *S : Ops) |
| 4134 | if (MaxType) |
| 4135 | MaxType = getWiderType(MaxType, S->getType()); |
| 4136 | else |
| 4137 | MaxType = S->getType(); |
| 4138 | assert(MaxType && "Failed to find maximum type!")(static_cast <bool> (MaxType && "Failed to find maximum type!" ) ? void (0) : __assert_fail ("MaxType && \"Failed to find maximum type!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 4138, __extension__ __PRETTY_FUNCTION__)); |
| 4139 | |
| 4140 | // Extend all ops to max type. |
| 4141 | SmallVector<const SCEV *, 2> PromotedOps; |
| 4142 | for (auto *S : Ops) |
| 4143 | PromotedOps.push_back(getNoopOrZeroExtend(S, MaxType)); |
| 4144 | |
| 4145 | // Generate umin. |
| 4146 | return getUMinExpr(PromotedOps); |
| 4147 | } |
| 4148 | |
| 4149 | const SCEV *ScalarEvolution::getPointerBase(const SCEV *V) { |
| 4150 | // A pointer operand may evaluate to a nonpointer expression, such as null. |
| 4151 | if (!V->getType()->isPointerTy()) |
| 4152 | return V; |
| 4153 | |
| 4154 | while (true) { |
| 4155 | if (const SCEVIntegralCastExpr *Cast = dyn_cast<SCEVIntegralCastExpr>(V)) { |
| 4156 | V = Cast->getOperand(); |
| 4157 | } else if (const SCEVNAryExpr *NAry = dyn_cast<SCEVNAryExpr>(V)) { |
| 4158 | const SCEV *PtrOp = nullptr; |
| 4159 | for (const SCEV *NAryOp : NAry->operands()) { |
| 4160 | if (NAryOp->getType()->isPointerTy()) { |
| 4161 | // Cannot find the base of an expression with multiple pointer ops. |
| 4162 | if (PtrOp) |
| 4163 | return V; |
| 4164 | PtrOp = NAryOp; |
| 4165 | } |
| 4166 | } |
| 4167 | if (!PtrOp) // All operands were non-pointer. |
| 4168 | return V; |
| 4169 | V = PtrOp; |
| 4170 | } else // Not something we can look further into. |
| 4171 | return V; |
| 4172 | } |
| 4173 | } |
| 4174 | |
| 4175 | /// Push users of the given Instruction onto the given Worklist. |
| 4176 | static void |
| 4177 | PushDefUseChildren(Instruction *I, |
| 4178 | SmallVectorImpl<Instruction *> &Worklist) { |
| 4179 | // Push the def-use children onto the Worklist stack. |
| 4180 | for (User *U : I->users()) |
| 4181 | Worklist.push_back(cast<Instruction>(U)); |
| 4182 | } |
| 4183 | |
| 4184 | void ScalarEvolution::forgetSymbolicName(Instruction *PN, const SCEV *SymName) { |
| 4185 | SmallVector<Instruction *, 16> Worklist; |
| 4186 | PushDefUseChildren(PN, Worklist); |
| 4187 | |
| 4188 | SmallPtrSet<Instruction *, 8> Visited; |
| 4189 | Visited.insert(PN); |
| 4190 | while (!Worklist.empty()) { |
| 4191 | Instruction *I = Worklist.pop_back_val(); |
| 4192 | if (!Visited.insert(I).second) |
| 4193 | continue; |
| 4194 | |
| 4195 | auto It = ValueExprMap.find_as(static_cast<Value *>(I)); |
| 4196 | if (It != ValueExprMap.end()) { |
| 4197 | const SCEV *Old = It->second; |
| 4198 | |
| 4199 | // Short-circuit the def-use traversal if the symbolic name |
| 4200 | // ceases to appear in expressions. |
| 4201 | if (Old != SymName && !hasOperand(Old, SymName)) |
| 4202 | continue; |
| 4203 | |
| 4204 | // SCEVUnknown for a PHI either means that it has an unrecognized |
| 4205 | // structure, it's a PHI that's in the progress of being computed |
| 4206 | // by createNodeForPHI, or it's a single-value PHI. In the first case, |
| 4207 | // additional loop trip count information isn't going to change anything. |
| 4208 | // In the second case, createNodeForPHI will perform the necessary |
| 4209 | // updates on its own when it gets to that point. In the third, we do |
| 4210 | // want to forget the SCEVUnknown. |
| 4211 | if (!isa<PHINode>(I) || |
| 4212 | !isa<SCEVUnknown>(Old) || |
| 4213 | (I != PN && Old == SymName)) { |
| 4214 | eraseValueFromMap(It->first); |
| 4215 | forgetMemoizedResults(Old); |
| 4216 | } |
| 4217 | } |
| 4218 | |
| 4219 | PushDefUseChildren(I, Worklist); |
| 4220 | } |
| 4221 | } |
| 4222 | |
| 4223 | namespace { |
| 4224 | |
| 4225 | /// Takes SCEV S and Loop L. For each AddRec sub-expression, use its start |
| 4226 | /// expression in case its Loop is L. If it is not L then |
| 4227 | /// if IgnoreOtherLoops is true then use AddRec itself |
| 4228 | /// otherwise rewrite cannot be done. |
| 4229 | /// If SCEV contains non-invariant unknown SCEV rewrite cannot be done. |
| 4230 | class SCEVInitRewriter : public SCEVRewriteVisitor<SCEVInitRewriter> { |
| 4231 | public: |
| 4232 | static const SCEV *rewrite(const SCEV *S, const Loop *L, ScalarEvolution &SE, |
| 4233 | bool IgnoreOtherLoops = true) { |
| 4234 | SCEVInitRewriter Rewriter(L, SE); |
| 4235 | const SCEV *Result = Rewriter.visit(S); |
| 4236 | if (Rewriter.hasSeenLoopVariantSCEVUnknown()) |
| 4237 | return SE.getCouldNotCompute(); |
| 4238 | return Rewriter.hasSeenOtherLoops() && !IgnoreOtherLoops |
| 4239 | ? SE.getCouldNotCompute() |
| 4240 | : Result; |
| 4241 | } |
| 4242 | |
| 4243 | const SCEV *visitUnknown(const SCEVUnknown *Expr) { |
| 4244 | if (!SE.isLoopInvariant(Expr, L)) |
| 4245 | SeenLoopVariantSCEVUnknown = true; |
| 4246 | return Expr; |
| 4247 | } |
| 4248 | |
| 4249 | const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) { |
| 4250 | // Only re-write AddRecExprs for this loop. |
| 4251 | if (Expr->getLoop() == L) |
| 4252 | return Expr->getStart(); |
| 4253 | SeenOtherLoops = true; |
| 4254 | return Expr; |
| 4255 | } |
| 4256 | |
| 4257 | bool hasSeenLoopVariantSCEVUnknown() { return SeenLoopVariantSCEVUnknown; } |
| 4258 | |
| 4259 | bool hasSeenOtherLoops() { return SeenOtherLoops; } |
| 4260 | |
| 4261 | private: |
| 4262 | explicit SCEVInitRewriter(const Loop *L, ScalarEvolution &SE) |
| 4263 | : SCEVRewriteVisitor(SE), L(L) {} |
| 4264 | |
| 4265 | const Loop *L; |
| 4266 | bool SeenLoopVariantSCEVUnknown = false; |
| 4267 | bool SeenOtherLoops = false; |
| 4268 | }; |
| 4269 | |
| 4270 | /// Takes SCEV S and Loop L. For each AddRec sub-expression, use its post |
| 4271 | /// increment expression in case its Loop is L. If it is not L then |
| 4272 | /// use AddRec itself. |
| 4273 | /// If SCEV contains non-invariant unknown SCEV rewrite cannot be done. |
| 4274 | class SCEVPostIncRewriter : public SCEVRewriteVisitor<SCEVPostIncRewriter> { |
| 4275 | public: |
| 4276 | static const SCEV *rewrite(const SCEV *S, const Loop *L, ScalarEvolution &SE) { |
| 4277 | SCEVPostIncRewriter Rewriter(L, SE); |
| 4278 | const SCEV *Result = Rewriter.visit(S); |
| 4279 | return Rewriter.hasSeenLoopVariantSCEVUnknown() |
| 4280 | ? SE.getCouldNotCompute() |
| 4281 | : Result; |
| 4282 | } |
| 4283 | |
| 4284 | const SCEV *visitUnknown(const SCEVUnknown *Expr) { |
| 4285 | if (!SE.isLoopInvariant(Expr, L)) |
| 4286 | SeenLoopVariantSCEVUnknown = true; |
| 4287 | return Expr; |
| 4288 | } |
| 4289 | |
| 4290 | const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) { |
| 4291 | // Only re-write AddRecExprs for this loop. |
| 4292 | if (Expr->getLoop() == L) |
| 4293 | return Expr->getPostIncExpr(SE); |
| 4294 | SeenOtherLoops = true; |
| 4295 | return Expr; |
| 4296 | } |
| 4297 | |
| 4298 | bool hasSeenLoopVariantSCEVUnknown() { return SeenLoopVariantSCEVUnknown; } |
| 4299 | |
| 4300 | bool hasSeenOtherLoops() { return SeenOtherLoops; } |
| 4301 | |
| 4302 | private: |
| 4303 | explicit SCEVPostIncRewriter(const Loop *L, ScalarEvolution &SE) |
| 4304 | : SCEVRewriteVisitor(SE), L(L) {} |
| 4305 | |
| 4306 | const Loop *L; |
| 4307 | bool SeenLoopVariantSCEVUnknown = false; |
| 4308 | bool SeenOtherLoops = false; |
| 4309 | }; |
| 4310 | |
| 4311 | /// This class evaluates the compare condition by matching it against the |
| 4312 | /// condition of loop latch. If there is a match we assume a true value |
| 4313 | /// for the condition while building SCEV nodes. |
| 4314 | class SCEVBackedgeConditionFolder |
| 4315 | : public SCEVRewriteVisitor<SCEVBackedgeConditionFolder> { |
| 4316 | public: |
| 4317 | static const SCEV *rewrite(const SCEV *S, const Loop *L, |
| 4318 | ScalarEvolution &SE) { |
| 4319 | bool IsPosBECond = false; |
| 4320 | Value *BECond = nullptr; |
| 4321 | if (BasicBlock *Latch = L->getLoopLatch()) { |
| 4322 | BranchInst *BI = dyn_cast<BranchInst>(Latch->getTerminator()); |
| 4323 | if (BI && BI->isConditional()) { |
| 4324 | assert(BI->getSuccessor(0) != BI->getSuccessor(1) &&(static_cast <bool> (BI->getSuccessor(0) != BI->getSuccessor (1) && "Both outgoing branches should not target same header!" ) ? void (0) : __assert_fail ("BI->getSuccessor(0) != BI->getSuccessor(1) && \"Both outgoing branches should not target same header!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 4325, __extension__ __PRETTY_FUNCTION__)) |
| 4325 | "Both outgoing branches should not target same header!")(static_cast <bool> (BI->getSuccessor(0) != BI->getSuccessor (1) && "Both outgoing branches should not target same header!" ) ? void (0) : __assert_fail ("BI->getSuccessor(0) != BI->getSuccessor(1) && \"Both outgoing branches should not target same header!\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 4325, __extension__ __PRETTY_FUNCTION__)); |
| 4326 | BECond = BI->getCondition(); |
| 4327 | IsPosBECond = BI->getSuccessor(0) == L->getHeader(); |
| 4328 | } else { |
| 4329 | return S; |
| 4330 | } |
| 4331 | } |
| 4332 | SCEVBackedgeConditionFolder Rewriter(L, BECond, IsPosBECond, SE); |
| 4333 | return Rewriter.visit(S); |
| 4334 | } |
| 4335 | |
| 4336 | const SCEV *visitUnknown(const SCEVUnknown *Expr) { |
| 4337 | const SCEV *Result = Expr; |
| 4338 | bool InvariantF = SE.isLoopInvariant(Expr, L); |
| 4339 | |
| 4340 | if (!InvariantF) { |
| 4341 | Instruction *I = cast<Instruction>(Expr->getValue()); |
| 4342 | switch (I->getOpcode()) { |
| 4343 | case Instruction::Select: { |
| 4344 | SelectInst *SI = cast<SelectInst>(I); |
| 4345 | Optional<const SCEV *> Res = |
| 4346 | compareWithBackedgeCondition(SI->getCondition()); |
| 4347 | if (Res.hasValue()) { |
| 4348 | bool IsOne = cast<SCEVConstant>(Res.getValue())->getValue()->isOne(); |
| 4349 | Result = SE.getSCEV(IsOne ? SI->getTrueValue() : SI->getFalseValue()); |
| 4350 | } |
| 4351 | break; |
| 4352 | } |
| 4353 | default: { |
| 4354 | Optional<const SCEV *> Res = compareWithBackedgeCondition(I); |
| 4355 | if (Res.hasValue()) |
| 4356 | Result = Res.getValue(); |
| 4357 | break; |
| 4358 | } |
| 4359 | } |
| 4360 | } |
| 4361 | return Result; |
| 4362 | } |
| 4363 | |
| 4364 | private: |
| 4365 | explicit SCEVBackedgeConditionFolder(const Loop *L, Value *BECond, |
| 4366 | bool IsPosBECond, ScalarEvolution &SE) |
| 4367 | : SCEVRewriteVisitor(SE), L(L), BackedgeCond(BECond), |
| 4368 | IsPositiveBECond(IsPosBECond) {} |
| 4369 | |
| 4370 | Optional<const SCEV *> compareWithBackedgeCondition(Value *IC); |
| 4371 | |
| 4372 | const Loop *L; |
| 4373 | /// Loop back condition. |
| 4374 | Value *BackedgeCond = nullptr; |
| 4375 | /// Set to true if loop back is on positive branch condition. |
| 4376 | bool IsPositiveBECond; |
| 4377 | }; |
| 4378 | |
| 4379 | Optional<const SCEV *> |
| 4380 | SCEVBackedgeConditionFolder::compareWithBackedgeCondition(Value *IC) { |
| 4381 | |
| 4382 | // If value matches the backedge condition for loop latch, |
| 4383 | // then return a constant evolution node based on loopback |
| 4384 | // branch taken. |
| 4385 | if (BackedgeCond == IC) |
| 4386 | return IsPositiveBECond ? SE.getOne(Type::getInt1Ty(SE.getContext())) |
| 4387 | : SE.getZero(Type::getInt1Ty(SE.getContext())); |
| 4388 | return None; |
| 4389 | } |
| 4390 | |
| 4391 | class SCEVShiftRewriter : public SCEVRewriteVisitor<SCEVShiftRewriter> { |
| 4392 | public: |
| 4393 | static const SCEV *rewrite(const SCEV *S, const Loop *L, |
| 4394 | ScalarEvolution &SE) { |
| 4395 | SCEVShiftRewriter Rewriter(L, SE); |
| 4396 | const SCEV *Result = Rewriter.visit(S); |
| 4397 | return Rewriter.isValid() ? Result : SE.getCouldNotCompute(); |
| 4398 | } |
| 4399 | |
| 4400 | const SCEV *visitUnknown(const SCEVUnknown *Expr) { |
| 4401 | // Only allow AddRecExprs for this loop. |
| 4402 | if (!SE.isLoopInvariant(Expr, L)) |
| 4403 | Valid = false; |
| 4404 | return Expr; |
| 4405 | } |
| 4406 | |
| 4407 | const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) { |
| 4408 | if (Expr->getLoop() == L && Expr->isAffine()) |
| 4409 | return SE.getMinusSCEV(Expr, Expr->getStepRecurrence(SE)); |
| 4410 | Valid = false; |
| 4411 | return Expr; |
| 4412 | } |
| 4413 | |
| 4414 | bool isValid() { return Valid; } |
| 4415 | |
| 4416 | private: |
| 4417 | explicit SCEVShiftRewriter(const Loop *L, ScalarEvolution &SE) |
| 4418 | : SCEVRewriteVisitor(SE), L(L) {} |
| 4419 | |
| 4420 | const Loop *L; |
| 4421 | bool Valid = true; |
| 4422 | }; |
| 4423 | |
| 4424 | } // end anonymous namespace |
| 4425 | |
| 4426 | SCEV::NoWrapFlags |
| 4427 | ScalarEvolution::proveNoWrapViaConstantRanges(const SCEVAddRecExpr *AR) { |
| 4428 | if (!AR->isAffine()) |
| 4429 | return SCEV::FlagAnyWrap; |
| 4430 | |
| 4431 | using OBO = OverflowingBinaryOperator; |
| 4432 | |
| 4433 | SCEV::NoWrapFlags Result = SCEV::FlagAnyWrap; |
| 4434 | |
| 4435 | if (!AR->hasNoSignedWrap()) { |
| 4436 | ConstantRange AddRecRange = getSignedRange(AR); |
| 4437 | ConstantRange IncRange = getSignedRange(AR->getStepRecurrence(*this)); |
| 4438 | |
| 4439 | auto NSWRegion = ConstantRange::makeGuaranteedNoWrapRegion( |
| 4440 | Instruction::Add, IncRange, OBO::NoSignedWrap); |
| 4441 | if (NSWRegion.contains(AddRecRange)) |
| 4442 | Result = ScalarEvolution::setFlags(Result, SCEV::FlagNSW); |
| 4443 | } |
| 4444 | |
| 4445 | if (!AR->hasNoUnsignedWrap()) { |
| 4446 | ConstantRange AddRecRange = getUnsignedRange(AR); |
| 4447 | ConstantRange IncRange = getUnsignedRange(AR->getStepRecurrence(*this)); |
| 4448 | |
| 4449 | auto NUWRegion = ConstantRange::makeGuaranteedNoWrapRegion( |
| 4450 | Instruction::Add, IncRange, OBO::NoUnsignedWrap); |
| 4451 | if (NUWRegion.contains(AddRecRange)) |
| 4452 | Result = ScalarEvolution::setFlags(Result, SCEV::FlagNUW); |
| 4453 | } |
| 4454 | |
| 4455 | return Result; |
| 4456 | } |
| 4457 | |
| 4458 | SCEV::NoWrapFlags |
| 4459 | ScalarEvolution::proveNoSignedWrapViaInduction(const SCEVAddRecExpr *AR) { |
| 4460 | SCEV::NoWrapFlags Result = AR->getNoWrapFlags(); |
| 4461 | |
| 4462 | if (AR->hasNoSignedWrap()) |
| 4463 | return Result; |
| 4464 | |
| 4465 | if (!AR->isAffine()) |
| 4466 | return Result; |
| 4467 | |
| 4468 | const SCEV *Step = AR->getStepRecurrence(*this); |
| 4469 | const Loop *L = AR->getLoop(); |
| 4470 | |
| 4471 | // Check whether the backedge-taken count is SCEVCouldNotCompute. |
| 4472 | // Note that this serves two purposes: It filters out loops that are |
| 4473 | // simply not analyzable, and it covers the case where this code is |
| 4474 | // being called from within backedge-taken count analysis, such that |
| 4475 | // attempting to ask for the backedge-taken count would likely result |
| 4476 | // in infinite recursion. In the later case, the analysis code will |
| 4477 | // cope with a conservative value, and it will take care to purge |
| 4478 | // that value once it has finished. |
| 4479 | const SCEV *MaxBECount = getConstantMaxBackedgeTakenCount(L); |
| 4480 | |
| 4481 | // Normally, in the cases we can prove no-overflow via a |
| 4482 | // backedge guarding condition, we can also compute a backedge |
| 4483 | // taken count for the loop. The exceptions are assumptions and |
| 4484 | // guards present in the loop -- SCEV is not great at exploiting |
| 4485 | // these to compute max backedge taken counts, but can still use |
| 4486 | // these to prove lack of overflow. Use this fact to avoid |
| 4487 | // doing extra work that may not pay off. |
| 4488 | |
| 4489 | if (isa<SCEVCouldNotCompute>(MaxBECount) && !HasGuards && |
| 4490 | AC.assumptions().empty()) |
| 4491 | return Result; |
| 4492 | |
| 4493 | // If the backedge is guarded by a comparison with the pre-inc value the |
| 4494 | // addrec is safe. Also, if the entry is guarded by a comparison with the |
| 4495 | // start value and the backedge is guarded by a comparison with the post-inc |
| 4496 | // value, the addrec is safe. |
| 4497 | ICmpInst::Predicate Pred; |
| 4498 | const SCEV *OverflowLimit = |
| 4499 | getSignedOverflowLimitForStep(Step, &Pred, this); |
| 4500 | if (OverflowLimit && |
| 4501 | (isLoopBackedgeGuardedByCond(L, Pred, AR, OverflowLimit) || |
| 4502 | isKnownOnEveryIteration(Pred, AR, OverflowLimit))) { |
| 4503 | Result = setFlags(Result, SCEV::FlagNSW); |
| 4504 | } |
| 4505 | return Result; |
| 4506 | } |
| 4507 | SCEV::NoWrapFlags |
| 4508 | ScalarEvolution::proveNoUnsignedWrapViaInduction(const SCEVAddRecExpr *AR) { |
| 4509 | SCEV::NoWrapFlags Result = AR->getNoWrapFlags(); |
| 4510 | |
| 4511 | if (AR->hasNoUnsignedWrap()) |
| 4512 | return Result; |
| 4513 | |
| 4514 | if (!AR->isAffine()) |
| 4515 | return Result; |
| 4516 | |
| 4517 | const SCEV *Step = AR->getStepRecurrence(*this); |
| 4518 | unsigned BitWidth = getTypeSizeInBits(AR->getType()); |
| 4519 | const Loop *L = AR->getLoop(); |
| 4520 | |
| 4521 | // Check whether the backedge-taken count is SCEVCouldNotCompute. |
| 4522 | // Note that this serves two purposes: It filters out loops that are |
| 4523 | // simply not analyzable, and it covers the case where this code is |
| 4524 | // being called from within backedge-taken count analysis, such that |
| 4525 | // attempting to ask for the backedge-taken count would likely result |
| 4526 | // in infinite recursion. In the later case, the analysis code will |
| 4527 | // cope with a conservative value, and it will take care to purge |
| 4528 | // that value once it has finished. |
| 4529 | const SCEV *MaxBECount = getConstantMaxBackedgeTakenCount(L); |
| 4530 | |
| 4531 | // Normally, in the cases we can prove no-overflow via a |
| 4532 | // backedge guarding condition, we can also compute a backedge |
| 4533 | // taken count for the loop. The exceptions are assumptions and |
| 4534 | // guards present in the loop -- SCEV is not great at exploiting |
| 4535 | // these to compute max backedge taken counts, but can still use |
| 4536 | // these to prove lack of overflow. Use this fact to avoid |
| 4537 | // doing extra work that may not pay off. |
| 4538 | |
| 4539 | if (isa<SCEVCouldNotCompute>(MaxBECount) && !HasGuards && |
| 4540 | AC.assumptions().empty()) |
| 4541 | return Result; |
| 4542 | |
| 4543 | // If the backedge is guarded by a comparison with the pre-inc value the |
| 4544 | // addrec is safe. Also, if the entry is guarded by a comparison with the |
| 4545 | // start value and the backedge is guarded by a comparison with the post-inc |
| 4546 | // value, the addrec is safe. |
| 4547 | if (isKnownPositive(Step)) { |
| 4548 | const SCEV *N = getConstant(APInt::getMinValue(BitWidth) - |
| 4549 | getUnsignedRangeMax(Step)); |
| 4550 | if (isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_ULT, AR, N) || |
| 4551 | isKnownOnEveryIteration(ICmpInst::ICMP_ULT, AR, N)) { |
| 4552 | Result = setFlags(Result, SCEV::FlagNUW); |
| 4553 | } |
| 4554 | } |
| 4555 | |
| 4556 | return Result; |
| 4557 | } |
| 4558 | |
| 4559 | namespace { |
| 4560 | |
| 4561 | /// Represents an abstract binary operation. This may exist as a |
| 4562 | /// normal instruction or constant expression, or may have been |
| 4563 | /// derived from an expression tree. |
| 4564 | struct BinaryOp { |
| 4565 | unsigned Opcode; |
| 4566 | Value *LHS; |
| 4567 | Value *RHS; |
| 4568 | bool IsNSW = false; |
| 4569 | bool IsNUW = false; |
| 4570 | |
| 4571 | /// Op is set if this BinaryOp corresponds to a concrete LLVM instruction or |
| 4572 | /// constant expression. |
| 4573 | Operator *Op = nullptr; |
| 4574 | |
| 4575 | explicit BinaryOp(Operator *Op) |
| 4576 | : Opcode(Op->getOpcode()), LHS(Op->getOperand(0)), RHS(Op->getOperand(1)), |
| 4577 | Op(Op) { |
| 4578 | if (auto *OBO = dyn_cast<OverflowingBinaryOperator>(Op)) { |
| 4579 | IsNSW = OBO->hasNoSignedWrap(); |
| 4580 | IsNUW = OBO->hasNoUnsignedWrap(); |
| 4581 | } |
| 4582 | } |
| 4583 | |
| 4584 | explicit BinaryOp(unsigned Opcode, Value *LHS, Value *RHS, bool IsNSW = false, |
| 4585 | bool IsNUW = false) |
| 4586 | : Opcode(Opcode), LHS(LHS), RHS(RHS), IsNSW(IsNSW), IsNUW(IsNUW) {} |
| 4587 | }; |
| 4588 | |
| 4589 | } // end anonymous namespace |
| 4590 | |
| 4591 | /// Try to map \p V into a BinaryOp, and return \c None on failure. |
| 4592 | static Optional<BinaryOp> MatchBinaryOp(Value *V, DominatorTree &DT) { |
| 4593 | auto *Op = dyn_cast<Operator>(V); |
| 4594 | if (!Op) |
| 4595 | return None; |
| 4596 | |
| 4597 | // Implementation detail: all the cleverness here should happen without |
| 4598 | // creating new SCEV expressions -- our caller knowns tricks to avoid creating |
| 4599 | // SCEV expressions when possible, and we should not break that. |
| 4600 | |
| 4601 | switch (Op->getOpcode()) { |
| 4602 | case Instruction::Add: |
| 4603 | case Instruction::Sub: |
| 4604 | case Instruction::Mul: |
| 4605 | case Instruction::UDiv: |
| 4606 | case Instruction::URem: |
| 4607 | case Instruction::And: |
| 4608 | case Instruction::Or: |
| 4609 | case Instruction::AShr: |
| 4610 | case Instruction::Shl: |
| 4611 | return BinaryOp(Op); |
| 4612 | |
| 4613 | case Instruction::Xor: |
| 4614 | if (auto *RHSC = dyn_cast<ConstantInt>(Op->getOperand(1))) |
| 4615 | // If the RHS of the xor is a signmask, then this is just an add. |
| 4616 | // Instcombine turns add of signmask into xor as a strength reduction step. |
| 4617 | if (RHSC->getValue().isSignMask()) |
| 4618 | return BinaryOp(Instruction::Add, Op->getOperand(0), Op->getOperand(1)); |
| 4619 | return BinaryOp(Op); |
| 4620 | |
| 4621 | case Instruction::LShr: |
| 4622 | // Turn logical shift right of a constant into a unsigned divide. |
| 4623 | if (ConstantInt *SA = dyn_cast<ConstantInt>(Op->getOperand(1))) { |
| 4624 | uint32_t BitWidth = cast<IntegerType>(Op->getType())->getBitWidth(); |
| 4625 | |
| 4626 | // If the shift count is not less than the bitwidth, the result of |
| 4627 | // the shift is undefined. Don't try to analyze it, because the |
| 4628 | // resolution chosen here may differ from the resolution chosen in |
| 4629 | // other parts of the compiler. |
| 4630 | if (SA->getValue().ult(BitWidth)) { |
| 4631 | Constant *X = |
| 4632 | ConstantInt::get(SA->getContext(), |
| 4633 | APInt::getOneBitSet(BitWidth, SA->getZExtValue())); |
| 4634 | return BinaryOp(Instruction::UDiv, Op->getOperand(0), X); |
| 4635 | } |
| 4636 | } |
| 4637 | return BinaryOp(Op); |
| 4638 | |
| 4639 | case Instruction::ExtractValue: { |
| 4640 | auto *EVI = cast<ExtractValueInst>(Op); |
| 4641 | if (EVI->getNumIndices() != 1 || EVI->getIndices()[0] != 0) |
| 4642 | break; |
| 4643 | |
| 4644 | auto *WO = dyn_cast<WithOverflowInst>(EVI->getAggregateOperand()); |
| 4645 | if (!WO) |
| 4646 | break; |
| 4647 | |
| 4648 | Instruction::BinaryOps BinOp = WO->getBinaryOp(); |
| 4649 | bool Signed = WO->isSigned(); |
| 4650 | // TODO: Should add nuw/nsw flags for mul as well. |
| 4651 | if (BinOp == Instruction::Mul || !isOverflowIntrinsicNoWrap(WO, DT)) |
| 4652 | return BinaryOp(BinOp, WO->getLHS(), WO->getRHS()); |
| 4653 | |
| 4654 | // Now that we know that all uses of the arithmetic-result component of |
| 4655 | // CI are guarded by the overflow check, we can go ahead and pretend |
| 4656 | // that the arithmetic is non-overflowing. |
| 4657 | return BinaryOp(BinOp, WO->getLHS(), WO->getRHS(), |
| 4658 | /* IsNSW = */ Signed, /* IsNUW = */ !Signed); |
| 4659 | } |
| 4660 | |
| 4661 | default: |
| 4662 | break; |
| 4663 | } |
| 4664 | |
| 4665 | // Recognise intrinsic loop.decrement.reg, and as this has exactly the same |
| 4666 | // semantics as a Sub, return a binary sub expression. |
| 4667 | if (auto *II = dyn_cast<IntrinsicInst>(V)) |
| 4668 | if (II->getIntrinsicID() == Intrinsic::loop_decrement_reg) |
| 4669 | return BinaryOp(Instruction::Sub, II->getOperand(0), II->getOperand(1)); |
| 4670 | |
| 4671 | return None; |
| 4672 | } |
| 4673 | |
| 4674 | /// Helper function to createAddRecFromPHIWithCasts. We have a phi |
| 4675 | /// node whose symbolic (unknown) SCEV is \p SymbolicPHI, which is updated via |
| 4676 | /// the loop backedge by a SCEVAddExpr, possibly also with a few casts on the |
| 4677 | /// way. This function checks if \p Op, an operand of this SCEVAddExpr, |
| 4678 | /// follows one of the following patterns: |
| 4679 | /// Op == (SExt ix (Trunc iy (%SymbolicPHI) to ix) to iy) |
| 4680 | /// Op == (ZExt ix (Trunc iy (%SymbolicPHI) to ix) to iy) |
| 4681 | /// If the SCEV expression of \p Op conforms with one of the expected patterns |
| 4682 | /// we return the type of the truncation operation, and indicate whether the |
| 4683 | /// truncated type should be treated as signed/unsigned by setting |
| 4684 | /// \p Signed to true/false, respectively. |
| 4685 | static Type *isSimpleCastedPHI(const SCEV *Op, const SCEVUnknown *SymbolicPHI, |
| 4686 | bool &Signed, ScalarEvolution &SE) { |
| 4687 | // The case where Op == SymbolicPHI (that is, with no type conversions on |
| 4688 | // the way) is handled by the regular add recurrence creating logic and |
| 4689 | // would have already been triggered in createAddRecForPHI. Reaching it here |
| 4690 | // means that createAddRecFromPHI had failed for this PHI before (e.g., |
| 4691 | // because one of the other operands of the SCEVAddExpr updating this PHI is |
| 4692 | // not invariant). |
| 4693 | // |
| 4694 | // Here we look for the case where Op = (ext(trunc(SymbolicPHI))), and in |
| 4695 | // this case predicates that allow us to prove that Op == SymbolicPHI will |
| 4696 | // be added. |
| 4697 | if (Op == SymbolicPHI) |
| 4698 | return nullptr; |
| 4699 | |
| 4700 | unsigned SourceBits = SE.getTypeSizeInBits(SymbolicPHI->getType()); |
| 4701 | unsigned NewBits = SE.getTypeSizeInBits(Op->getType()); |
| 4702 | if (SourceBits != NewBits) |
| 4703 | return nullptr; |
| 4704 | |
| 4705 | const SCEVSignExtendExpr *SExt = dyn_cast<SCEVSignExtendExpr>(Op); |
| 4706 | const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(Op); |
| 4707 | if (!SExt && !ZExt) |
| 4708 | return nullptr; |
| 4709 | const SCEVTruncateExpr *Trunc = |
| 4710 | SExt ? dyn_cast<SCEVTruncateExpr>(SExt->getOperand()) |
| 4711 | : dyn_cast<SCEVTruncateExpr>(ZExt->getOperand()); |
| 4712 | if (!Trunc) |
| 4713 | return nullptr; |
| 4714 | const SCEV *X = Trunc->getOperand(); |
| 4715 | if (X != SymbolicPHI) |
| 4716 | return nullptr; |
| 4717 | Signed = SExt != nullptr; |
| 4718 | return Trunc->getType(); |
| 4719 | } |
| 4720 | |
| 4721 | static const Loop *isIntegerLoopHeaderPHI(const PHINode *PN, LoopInfo &LI) { |
| 4722 | if (!PN->getType()->isIntegerTy()) |
| 4723 | return nullptr; |
| 4724 | const Loop *L = LI.getLoopFor(PN->getParent()); |
| 4725 | if (!L || L->getHeader() != PN->getParent()) |
| 4726 | return nullptr; |
| 4727 | return L; |
| 4728 | } |
| 4729 | |
| 4730 | // Analyze \p SymbolicPHI, a SCEV expression of a phi node, and check if the |
| 4731 | // computation that updates the phi follows the following pattern: |
| 4732 | // (SExt/ZExt ix (Trunc iy (%SymbolicPHI) to ix) to iy) + InvariantAccum |
| 4733 | // which correspond to a phi->trunc->sext/zext->add->phi update chain. |
| 4734 | // If so, try to see if it can be rewritten as an AddRecExpr under some |
| 4735 | // Predicates. If successful, return them as a pair. Also cache the results |
| 4736 | // of the analysis. |
| 4737 | // |
| 4738 | // Example usage scenario: |
| 4739 | // Say the Rewriter is called for the following SCEV: |
| 4740 | // 8 * ((sext i32 (trunc i64 %X to i32) to i64) + %Step) |
| 4741 | // where: |
| 4742 | // %X = phi i64 (%Start, %BEValue) |
| 4743 | // It will visitMul->visitAdd->visitSExt->visitTrunc->visitUnknown(%X), |
| 4744 | // and call this function with %SymbolicPHI = %X. |
| 4745 | // |
| 4746 | // The analysis will find that the value coming around the backedge has |
| 4747 | // the following SCEV: |
| 4748 | // BEValue = ((sext i32 (trunc i64 %X to i32) to i64) + %Step) |
| 4749 | // Upon concluding that this matches the desired pattern, the function |
| 4750 | // will return the pair {NewAddRec, SmallPredsVec} where: |
| 4751 | // NewAddRec = {%Start,+,%Step} |
| 4752 | // SmallPredsVec = {P1, P2, P3} as follows: |
| 4753 | // P1(WrapPred): AR: {trunc(%Start),+,(trunc %Step)}<nsw> Flags: <nssw> |
| 4754 | // P2(EqualPred): %Start == (sext i32 (trunc i64 %Start to i32) to i64) |
| 4755 | // P3(EqualPred): %Step == (sext i32 (trunc i64 %Step to i32) to i64) |
| 4756 | // The returned pair means that SymbolicPHI can be rewritten into NewAddRec |
| 4757 | // under the predicates {P1,P2,P3}. |
| 4758 | // This predicated rewrite will be cached in PredicatedSCEVRewrites: |
| 4759 | // PredicatedSCEVRewrites[{%X,L}] = {NewAddRec, {P1,P2,P3)} |
| 4760 | // |
| 4761 | // TODO's: |
| 4762 | // |
| 4763 | // 1) Extend the Induction descriptor to also support inductions that involve |
| 4764 | // casts: When needed (namely, when we are called in the context of the |
| 4765 | // vectorizer induction analysis), a Set of cast instructions will be |
| 4766 | // populated by this method, and provided back to isInductionPHI. This is |
| 4767 | // needed to allow the vectorizer to properly record them to be ignored by |
| 4768 | // the cost model and to avoid vectorizing them (otherwise these casts, |
| 4769 | // which are redundant under the runtime overflow checks, will be |
| 4770 | // vectorized, which can be costly). |
| 4771 | // |
| 4772 | // 2) Support additional induction/PHISCEV patterns: We also want to support |
| 4773 | // inductions where the sext-trunc / zext-trunc operations (partly) occur |
| 4774 | // after the induction update operation (the induction increment): |
| 4775 | // |
| 4776 | // (Trunc iy (SExt/ZExt ix (%SymbolicPHI + InvariantAccum) to iy) to ix) |
| 4777 | // which correspond to a phi->add->trunc->sext/zext->phi update chain. |
| 4778 | // |
| 4779 | // (Trunc iy ((SExt/ZExt ix (%SymbolicPhi) to iy) + InvariantAccum) to ix) |
| 4780 | // which correspond to a phi->trunc->add->sext/zext->phi update chain. |
| 4781 | // |
| 4782 | // 3) Outline common code with createAddRecFromPHI to avoid duplication. |
| 4783 | Optional<std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>>> |
| 4784 | ScalarEvolution::createAddRecFromPHIWithCastsImpl(const SCEVUnknown *SymbolicPHI) { |
| 4785 | SmallVector<const SCEVPredicate *, 3> Predicates; |
| 4786 | |
| 4787 | // *** Part1: Analyze if we have a phi-with-cast pattern for which we can |
| 4788 | // return an AddRec expression under some predicate. |
| 4789 | |
| 4790 | auto *PN = cast<PHINode>(SymbolicPHI->getValue()); |
| 4791 | const Loop *L = isIntegerLoopHeaderPHI(PN, LI); |
| 4792 | assert(L && "Expecting an integer loop header phi")(static_cast <bool> (L && "Expecting an integer loop header phi" ) ? void (0) : __assert_fail ("L && \"Expecting an integer loop header phi\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 4792, __extension__ __PRETTY_FUNCTION__)); |
| 4793 | |
| 4794 | // The loop may have multiple entrances or multiple exits; we can analyze |
| 4795 | // this phi as an addrec if it has a unique entry value and a unique |
| 4796 | // backedge value. |
| 4797 | Value *BEValueV = nullptr, *StartValueV = nullptr; |
| 4798 | for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) { |
| 4799 | Value *V = PN->getIncomingValue(i); |
| 4800 | if (L->contains(PN->getIncomingBlock(i))) { |
| 4801 | if (!BEValueV) { |
| 4802 | BEValueV = V; |
| 4803 | } else if (BEValueV != V) { |
| 4804 | BEValueV = nullptr; |
| 4805 | break; |
| 4806 | } |
| 4807 | } else if (!StartValueV) { |
| 4808 | StartValueV = V; |
| 4809 | } else if (StartValueV != V) { |
| 4810 | StartValueV = nullptr; |
| 4811 | break; |
| 4812 | } |
| 4813 | } |
| 4814 | if (!BEValueV || !StartValueV) |
| 4815 | return None; |
| 4816 | |
| 4817 | const SCEV *BEValue = getSCEV(BEValueV); |
| 4818 | |
| 4819 | // If the value coming around the backedge is an add with the symbolic |
| 4820 | // value we just inserted, possibly with casts that we can ignore under |
| 4821 | // an appropriate runtime guard, then we found a simple induction variable! |
| 4822 | const auto *Add = dyn_cast<SCEVAddExpr>(BEValue); |
| 4823 | if (!Add) |
| 4824 | return None; |
| 4825 | |
| 4826 | // If there is a single occurrence of the symbolic value, possibly |
| 4827 | // casted, replace it with a recurrence. |
| 4828 | unsigned FoundIndex = Add->getNumOperands(); |
| 4829 | Type *TruncTy = nullptr; |
| 4830 | bool Signed; |
| 4831 | for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i) |
| 4832 | if ((TruncTy = |
| 4833 | isSimpleCastedPHI(Add->getOperand(i), SymbolicPHI, Signed, *this))) |
| 4834 | if (FoundIndex == e) { |
| 4835 | FoundIndex = i; |
| 4836 | break; |
| 4837 | } |
| 4838 | |
| 4839 | if (FoundIndex == Add->getNumOperands()) |
| 4840 | return None; |
| 4841 | |
| 4842 | // Create an add with everything but the specified operand. |
| 4843 | SmallVector<const SCEV *, 8> Ops; |
| 4844 | for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i) |
| 4845 | if (i != FoundIndex) |
| 4846 | Ops.push_back(Add->getOperand(i)); |
| 4847 | const SCEV *Accum = getAddExpr(Ops); |
| 4848 | |
| 4849 | // The runtime checks will not be valid if the step amount is |
| 4850 | // varying inside the loop. |
| 4851 | if (!isLoopInvariant(Accum, L)) |
| 4852 | return None; |
| 4853 | |
| 4854 | // *** Part2: Create the predicates |
| 4855 | |
| 4856 | // Analysis was successful: we have a phi-with-cast pattern for which we |
| 4857 | // can return an AddRec expression under the following predicates: |
| 4858 | // |
| 4859 | // P1: A Wrap predicate that guarantees that Trunc(Start) + i*Trunc(Accum) |
| 4860 | // fits within the truncated type (does not overflow) for i = 0 to n-1. |
| 4861 | // P2: An Equal predicate that guarantees that |
| 4862 | // Start = (Ext ix (Trunc iy (Start) to ix) to iy) |
| 4863 | // P3: An Equal predicate that guarantees that |
| 4864 | // Accum = (Ext ix (Trunc iy (Accum) to ix) to iy) |
| 4865 | // |
| 4866 | // As we next prove, the above predicates guarantee that: |
| 4867 | // Start + i*Accum = (Ext ix (Trunc iy ( Start + i*Accum ) to ix) to iy) |
| 4868 | // |
| 4869 | // |
| 4870 | // More formally, we want to prove that: |
| 4871 | // Expr(i+1) = Start + (i+1) * Accum |
| 4872 | // = (Ext ix (Trunc iy (Expr(i)) to ix) to iy) + Accum |
| 4873 | // |
| 4874 | // Given that: |
| 4875 | // 1) Expr(0) = Start |
| 4876 | // 2) Expr(1) = Start + Accum |
| 4877 | // = (Ext ix (Trunc iy (Start) to ix) to iy) + Accum :: from P2 |
| 4878 | // 3) Induction hypothesis (step i): |
| 4879 | // Expr(i) = (Ext ix (Trunc iy (Expr(i-1)) to ix) to iy) + Accum |
| 4880 | // |
| 4881 | // Proof: |
| 4882 | // Expr(i+1) = |
| 4883 | // = Start + (i+1)*Accum |
| 4884 | // = (Start + i*Accum) + Accum |
| 4885 | // = Expr(i) + Accum |
| 4886 | // = (Ext ix (Trunc iy (Expr(i-1)) to ix) to iy) + Accum + Accum |
| 4887 | // :: from step i |
| 4888 | // |
| 4889 | // = (Ext ix (Trunc iy (Start + (i-1)*Accum) to ix) to iy) + Accum + Accum |
| 4890 | // |
| 4891 | // = (Ext ix (Trunc iy (Start + (i-1)*Accum) to ix) to iy) |
| 4892 | // + (Ext ix (Trunc iy (Accum) to ix) to iy) |
| 4893 | // + Accum :: from P3 |
| 4894 | // |
| 4895 | // = (Ext ix (Trunc iy ((Start + (i-1)*Accum) + Accum) to ix) to iy) |
| 4896 | // + Accum :: from P1: Ext(x)+Ext(y)=>Ext(x+y) |
| 4897 | // |
| 4898 | // = (Ext ix (Trunc iy (Start + i*Accum) to ix) to iy) + Accum |
| 4899 | // = (Ext ix (Trunc iy (Expr(i)) to ix) to iy) + Accum |
| 4900 | // |
| 4901 | // By induction, the same applies to all iterations 1<=i<n: |
| 4902 | // |
| 4903 | |
| 4904 | // Create a truncated addrec for which we will add a no overflow check (P1). |
| 4905 | const SCEV *StartVal = getSCEV(StartValueV); |
| 4906 | const SCEV *PHISCEV = |
| 4907 | getAddRecExpr(getTruncateExpr(StartVal, TruncTy), |
| 4908 | getTruncateExpr(Accum, TruncTy), L, SCEV::FlagAnyWrap); |
| 4909 | |
| 4910 | // PHISCEV can be either a SCEVConstant or a SCEVAddRecExpr. |
| 4911 | // ex: If truncated Accum is 0 and StartVal is a constant, then PHISCEV |
| 4912 | // will be constant. |
| 4913 | // |
| 4914 | // If PHISCEV is a constant, then P1 degenerates into P2 or P3, so we don't |
| 4915 | // add P1. |
| 4916 | if (const auto *AR = dyn_cast<SCEVAddRecExpr>(PHISCEV)) { |
| 4917 | SCEVWrapPredicate::IncrementWrapFlags AddedFlags = |
| 4918 | Signed ? SCEVWrapPredicate::IncrementNSSW |
| 4919 | : SCEVWrapPredicate::IncrementNUSW; |
| 4920 | const SCEVPredicate *AddRecPred = getWrapPredicate(AR, AddedFlags); |
| 4921 | Predicates.push_back(AddRecPred); |
| 4922 | } |
| 4923 | |
| 4924 | // Create the Equal Predicates P2,P3: |
| 4925 | |
| 4926 | // It is possible that the predicates P2 and/or P3 are computable at |
| 4927 | // compile time due to StartVal and/or Accum being constants. |
| 4928 | // If either one is, then we can check that now and escape if either P2 |
| 4929 | // or P3 is false. |
| 4930 | |
| 4931 | // Construct the extended SCEV: (Ext ix (Trunc iy (Expr) to ix) to iy) |
| 4932 | // for each of StartVal and Accum |
| 4933 | auto getExtendedExpr = [&](const SCEV *Expr, |
| 4934 | bool CreateSignExtend) -> const SCEV * { |
| 4935 | assert(isLoopInvariant(Expr, L) && "Expr is expected to be invariant")(static_cast <bool> (isLoopInvariant(Expr, L) && "Expr is expected to be invariant") ? void (0) : __assert_fail ("isLoopInvariant(Expr, L) && \"Expr is expected to be invariant\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 4935, __extension__ __PRETTY_FUNCTION__)); |
| 4936 | const SCEV *TruncatedExpr = getTruncateExpr(Expr, TruncTy); |
| 4937 | const SCEV *ExtendedExpr = |
| 4938 | CreateSignExtend ? getSignExtendExpr(TruncatedExpr, Expr->getType()) |
| 4939 | : getZeroExtendExpr(TruncatedExpr, Expr->getType()); |
| 4940 | return ExtendedExpr; |
| 4941 | }; |
| 4942 | |
| 4943 | // Given: |
| 4944 | // ExtendedExpr = (Ext ix (Trunc iy (Expr) to ix) to iy |
| 4945 | // = getExtendedExpr(Expr) |
| 4946 | // Determine whether the predicate P: Expr == ExtendedExpr |
| 4947 | // is known to be false at compile time |
| 4948 | auto PredIsKnownFalse = [&](const SCEV *Expr, |
| 4949 | const SCEV *ExtendedExpr) -> bool { |
| 4950 | return Expr != ExtendedExpr && |
| 4951 | isKnownPredicate(ICmpInst::ICMP_NE, Expr, ExtendedExpr); |
| 4952 | }; |
| 4953 | |
| 4954 | const SCEV *StartExtended = getExtendedExpr(StartVal, Signed); |
| 4955 | if (PredIsKnownFalse(StartVal, StartExtended)) { |
| 4956 | LLVM_DEBUG(dbgs() << "P2 is compile-time false\n";)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { dbgs() << "P2 is compile-time false\n" ;; } } while (false); |
| 4957 | return None; |
| 4958 | } |
| 4959 | |
| 4960 | // The Step is always Signed (because the overflow checks are either |
| 4961 | // NSSW or NUSW) |
| 4962 | const SCEV *AccumExtended = getExtendedExpr(Accum, /*CreateSignExtend=*/true); |
| 4963 | if (PredIsKnownFalse(Accum, AccumExtended)) { |
| 4964 | LLVM_DEBUG(dbgs() << "P3 is compile-time false\n";)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { dbgs() << "P3 is compile-time false\n" ;; } } while (false); |
| 4965 | return None; |
| 4966 | } |
| 4967 | |
| 4968 | auto AppendPredicate = [&](const SCEV *Expr, |
| 4969 | const SCEV *ExtendedExpr) -> void { |
| 4970 | if (Expr != ExtendedExpr && |
| 4971 | !isKnownPredicate(ICmpInst::ICMP_EQ, Expr, ExtendedExpr)) { |
| 4972 | const SCEVPredicate *Pred = getEqualPredicate(Expr, ExtendedExpr); |
| 4973 | LLVM_DEBUG(dbgs() << "Added Predicate: " << *Pred)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { dbgs() << "Added Predicate: " << *Pred; } } while (false); |
| 4974 | Predicates.push_back(Pred); |
| 4975 | } |
| 4976 | }; |
| 4977 | |
| 4978 | AppendPredicate(StartVal, StartExtended); |
| 4979 | AppendPredicate(Accum, AccumExtended); |
| 4980 | |
| 4981 | // *** Part3: Predicates are ready. Now go ahead and create the new addrec in |
| 4982 | // which the casts had been folded away. The caller can rewrite SymbolicPHI |
| 4983 | // into NewAR if it will also add the runtime overflow checks specified in |
| 4984 | // Predicates. |
| 4985 | auto *NewAR = getAddRecExpr(StartVal, Accum, L, SCEV::FlagAnyWrap); |
| 4986 | |
| 4987 | std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>> PredRewrite = |
| 4988 | std::make_pair(NewAR, Predicates); |
| 4989 | // Remember the result of the analysis for this SCEV at this locayyytion. |
| 4990 | PredicatedSCEVRewrites[{SymbolicPHI, L}] = PredRewrite; |
| 4991 | return PredRewrite; |
| 4992 | } |
| 4993 | |
| 4994 | Optional<std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>>> |
| 4995 | ScalarEvolution::createAddRecFromPHIWithCasts(const SCEVUnknown *SymbolicPHI) { |
| 4996 | auto *PN = cast<PHINode>(SymbolicPHI->getValue()); |
| 4997 | const Loop *L = isIntegerLoopHeaderPHI(PN, LI); |
| 4998 | if (!L) |
| 4999 | return None; |
| 5000 | |
| 5001 | // Check to see if we already analyzed this PHI. |
| 5002 | auto I = PredicatedSCEVRewrites.find({SymbolicPHI, L}); |
| 5003 | if (I != PredicatedSCEVRewrites.end()) { |
| 5004 | std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>> Rewrite = |
| 5005 | I->second; |
| 5006 | // Analysis was done before and failed to create an AddRec: |
| 5007 | if (Rewrite.first == SymbolicPHI) |
| 5008 | return None; |
| 5009 | // Analysis was done before and succeeded to create an AddRec under |
| 5010 | // a predicate: |
| 5011 | assert(isa<SCEVAddRecExpr>(Rewrite.first) && "Expected an AddRec")(static_cast <bool> (isa<SCEVAddRecExpr>(Rewrite. first) && "Expected an AddRec") ? void (0) : __assert_fail ("isa<SCEVAddRecExpr>(Rewrite.first) && \"Expected an AddRec\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 5011, __extension__ __PRETTY_FUNCTION__)); |
| 5012 | assert(!(Rewrite.second).empty() && "Expected to find Predicates")(static_cast <bool> (!(Rewrite.second).empty() && "Expected to find Predicates") ? void (0) : __assert_fail ("!(Rewrite.second).empty() && \"Expected to find Predicates\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 5012, __extension__ __PRETTY_FUNCTION__)); |
| 5013 | return Rewrite; |
| 5014 | } |
| 5015 | |
| 5016 | Optional<std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>>> |
| 5017 | Rewrite = createAddRecFromPHIWithCastsImpl(SymbolicPHI); |
| 5018 | |
| 5019 | // Record in the cache that the analysis failed |
| 5020 | if (!Rewrite) { |
| 5021 | SmallVector<const SCEVPredicate *, 3> Predicates; |
| 5022 | PredicatedSCEVRewrites[{SymbolicPHI, L}] = {SymbolicPHI, Predicates}; |
| 5023 | return None; |
| 5024 | } |
| 5025 | |
| 5026 | return Rewrite; |
| 5027 | } |
| 5028 | |
| 5029 | // FIXME: This utility is currently required because the Rewriter currently |
| 5030 | // does not rewrite this expression: |
| 5031 | // {0, +, (sext ix (trunc iy to ix) to iy)} |
| 5032 | // into {0, +, %step}, |
| 5033 | // even when the following Equal predicate exists: |
| 5034 | // "%step == (sext ix (trunc iy to ix) to iy)". |
| 5035 | bool PredicatedScalarEvolution::areAddRecsEqualWithPreds( |
| 5036 | const SCEVAddRecExpr *AR1, const SCEVAddRecExpr *AR2) const { |
| 5037 | if (AR1 == AR2) |
| 5038 | return true; |
| 5039 | |
| 5040 | auto areExprsEqual = [&](const SCEV *Expr1, const SCEV *Expr2) -> bool { |
| 5041 | if (Expr1 != Expr2 && !Preds.implies(SE.getEqualPredicate(Expr1, Expr2)) && |
| 5042 | !Preds.implies(SE.getEqualPredicate(Expr2, Expr1))) |
| 5043 | return false; |
| 5044 | return true; |
| 5045 | }; |
| 5046 | |
| 5047 | if (!areExprsEqual(AR1->getStart(), AR2->getStart()) || |
| 5048 | !areExprsEqual(AR1->getStepRecurrence(SE), AR2->getStepRecurrence(SE))) |
| 5049 | return false; |
| 5050 | return true; |
| 5051 | } |
| 5052 | |
| 5053 | /// A helper function for createAddRecFromPHI to handle simple cases. |
| 5054 | /// |
| 5055 | /// This function tries to find an AddRec expression for the simplest (yet most |
| 5056 | /// common) cases: PN = PHI(Start, OP(Self, LoopInvariant)). |
| 5057 | /// If it fails, createAddRecFromPHI will use a more general, but slow, |
| 5058 | /// technique for finding the AddRec expression. |
| 5059 | const SCEV *ScalarEvolution::createSimpleAffineAddRec(PHINode *PN, |
| 5060 | Value *BEValueV, |
| 5061 | Value *StartValueV) { |
| 5062 | const Loop *L = LI.getLoopFor(PN->getParent()); |
| 5063 | assert(L && L->getHeader() == PN->getParent())(static_cast <bool> (L && L->getHeader() == PN ->getParent()) ? void (0) : __assert_fail ("L && L->getHeader() == PN->getParent()" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 5063, __extension__ __PRETTY_FUNCTION__)); |
| 5064 | assert(BEValueV && StartValueV)(static_cast <bool> (BEValueV && StartValueV) ? void (0) : __assert_fail ("BEValueV && StartValueV", "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 5064, __extension__ __PRETTY_FUNCTION__)); |
| 5065 | |
| 5066 | auto BO = MatchBinaryOp(BEValueV, DT); |
| 5067 | if (!BO) |
| 5068 | return nullptr; |
| 5069 | |
| 5070 | if (BO->Opcode != Instruction::Add) |
| 5071 | return nullptr; |
| 5072 | |
| 5073 | const SCEV *Accum = nullptr; |
| 5074 | if (BO->LHS == PN && L->isLoopInvariant(BO->RHS)) |
| 5075 | Accum = getSCEV(BO->RHS); |
| 5076 | else if (BO->RHS == PN && L->isLoopInvariant(BO->LHS)) |
| 5077 | Accum = getSCEV(BO->LHS); |
| 5078 | |
| 5079 | if (!Accum) |
| 5080 | return nullptr; |
| 5081 | |
| 5082 | SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap; |
| 5083 | if (BO->IsNUW) |
| 5084 | Flags = setFlags(Flags, SCEV::FlagNUW); |
| 5085 | if (BO->IsNSW) |
| 5086 | Flags = setFlags(Flags, SCEV::FlagNSW); |
| 5087 | |
| 5088 | const SCEV *StartVal = getSCEV(StartValueV); |
| 5089 | const SCEV *PHISCEV = getAddRecExpr(StartVal, Accum, L, Flags); |
| 5090 | |
| 5091 | ValueExprMap[SCEVCallbackVH(PN, this)] = PHISCEV; |
| 5092 | |
| 5093 | // We can add Flags to the post-inc expression only if we |
| 5094 | // know that it is *undefined behavior* for BEValueV to |
| 5095 | // overflow. |
| 5096 | if (auto *BEInst = dyn_cast<Instruction>(BEValueV)) |
| 5097 | if (isLoopInvariant(Accum, L) && isAddRecNeverPoison(BEInst, L)) |
| 5098 | (void)getAddRecExpr(getAddExpr(StartVal, Accum), Accum, L, Flags); |
| 5099 | |
| 5100 | return PHISCEV; |
| 5101 | } |
| 5102 | |
| 5103 | const SCEV *ScalarEvolution::createAddRecFromPHI(PHINode *PN) { |
| 5104 | const Loop *L = LI.getLoopFor(PN->getParent()); |
| 5105 | if (!L || L->getHeader() != PN->getParent()) |
| 5106 | return nullptr; |
| 5107 | |
| 5108 | // The loop may have multiple entrances or multiple exits; we can analyze |
| 5109 | // this phi as an addrec if it has a unique entry value and a unique |
| 5110 | // backedge value. |
| 5111 | Value *BEValueV = nullptr, *StartValueV = nullptr; |
| 5112 | for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) { |
| 5113 | Value *V = PN->getIncomingValue(i); |
| 5114 | if (L->contains(PN->getIncomingBlock(i))) { |
| 5115 | if (!BEValueV) { |
| 5116 | BEValueV = V; |
| 5117 | } else if (BEValueV != V) { |
| 5118 | BEValueV = nullptr; |
| 5119 | break; |
| 5120 | } |
| 5121 | } else if (!StartValueV) { |
| 5122 | StartValueV = V; |
| 5123 | } else if (StartValueV != V) { |
| 5124 | StartValueV = nullptr; |
| 5125 | break; |
| 5126 | } |
| 5127 | } |
| 5128 | if (!BEValueV || !StartValueV) |
| 5129 | return nullptr; |
| 5130 | |
| 5131 | assert(ValueExprMap.find_as(PN) == ValueExprMap.end() &&(static_cast <bool> (ValueExprMap.find_as(PN) == ValueExprMap .end() && "PHI node already processed?") ? void (0) : __assert_fail ("ValueExprMap.find_as(PN) == ValueExprMap.end() && \"PHI node already processed?\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 5132, __extension__ __PRETTY_FUNCTION__)) |
| 5132 | "PHI node already processed?")(static_cast <bool> (ValueExprMap.find_as(PN) == ValueExprMap .end() && "PHI node already processed?") ? void (0) : __assert_fail ("ValueExprMap.find_as(PN) == ValueExprMap.end() && \"PHI node already processed?\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 5132, __extension__ __PRETTY_FUNCTION__)); |
| 5133 | |
| 5134 | // First, try to find AddRec expression without creating a fictituos symbolic |
| 5135 | // value for PN. |
| 5136 | if (auto *S = createSimpleAffineAddRec(PN, BEValueV, StartValueV)) |
| 5137 | return S; |
| 5138 | |
| 5139 | // Handle PHI node value symbolically. |
| 5140 | const SCEV *SymbolicName = getUnknown(PN); |
| 5141 | ValueExprMap.insert({SCEVCallbackVH(PN, this), SymbolicName}); |
| 5142 | |
| 5143 | // Using this symbolic name for the PHI, analyze the value coming around |
| 5144 | // the back-edge. |
| 5145 | const SCEV *BEValue = getSCEV(BEValueV); |
| 5146 | |
| 5147 | // NOTE: If BEValue is loop invariant, we know that the PHI node just |
| 5148 | // has a special value for the first iteration of the loop. |
| 5149 | |
| 5150 | // If the value coming around the backedge is an add with the symbolic |
| 5151 | // value we just inserted, then we found a simple induction variable! |
| 5152 | if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(BEValue)) { |
| 5153 | // If there is a single occurrence of the symbolic value, replace it |
| 5154 | // with a recurrence. |
| 5155 | unsigned FoundIndex = Add->getNumOperands(); |
| 5156 | for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i) |
| 5157 | if (Add->getOperand(i) == SymbolicName) |
| 5158 | if (FoundIndex == e) { |
| 5159 | FoundIndex = i; |
| 5160 | break; |
| 5161 | } |
| 5162 | |
| 5163 | if (FoundIndex != Add->getNumOperands()) { |
| 5164 | // Create an add with everything but the specified operand. |
| 5165 | SmallVector<const SCEV *, 8> Ops; |
| 5166 | for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i) |
| 5167 | if (i != FoundIndex) |
| 5168 | Ops.push_back(SCEVBackedgeConditionFolder::rewrite(Add->getOperand(i), |
| 5169 | L, *this)); |
| 5170 | const SCEV *Accum = getAddExpr(Ops); |
| 5171 | |
| 5172 | // This is not a valid addrec if the step amount is varying each |
| 5173 | // loop iteration, but is not itself an addrec in this loop. |
| 5174 | if (isLoopInvariant(Accum, L) || |
| 5175 | (isa<SCEVAddRecExpr>(Accum) && |
| 5176 | cast<SCEVAddRecExpr>(Accum)->getLoop() == L)) { |
| 5177 | SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap; |
| 5178 | |
| 5179 | if (auto BO = MatchBinaryOp(BEValueV, DT)) { |
| 5180 | if (BO->Opcode == Instruction::Add && BO->LHS == PN) { |
| 5181 | if (BO->IsNUW) |
| 5182 | Flags = setFlags(Flags, SCEV::FlagNUW); |
| 5183 | if (BO->IsNSW) |
| 5184 | Flags = setFlags(Flags, SCEV::FlagNSW); |
| 5185 | } |
| 5186 | } else if (GEPOperator *GEP = dyn_cast<GEPOperator>(BEValueV)) { |
| 5187 | // If the increment is an inbounds GEP, then we know the address |
| 5188 | // space cannot be wrapped around. We cannot make any guarantee |
| 5189 | // about signed or unsigned overflow because pointers are |
| 5190 | // unsigned but we may have a negative index from the base |
| 5191 | // pointer. We can guarantee that no unsigned wrap occurs if the |
| 5192 | // indices form a positive value. |
| 5193 | if (GEP->isInBounds() && GEP->getOperand(0) == PN) { |
| 5194 | Flags = setFlags(Flags, SCEV::FlagNW); |
| 5195 | |
| 5196 | const SCEV *Ptr = getSCEV(GEP->getPointerOperand()); |
| 5197 | if (isKnownPositive(getMinusSCEV(getSCEV(GEP), Ptr))) |
| 5198 | Flags = setFlags(Flags, SCEV::FlagNUW); |
| 5199 | } |
| 5200 | |
| 5201 | // We cannot transfer nuw and nsw flags from subtraction |
| 5202 | // operations -- sub nuw X, Y is not the same as add nuw X, -Y |
| 5203 | // for instance. |
| 5204 | } |
| 5205 | |
| 5206 | const SCEV *StartVal = getSCEV(StartValueV); |
| 5207 | const SCEV *PHISCEV = getAddRecExpr(StartVal, Accum, L, Flags); |
| 5208 | |
| 5209 | // Okay, for the entire analysis of this edge we assumed the PHI |
| 5210 | // to be symbolic. We now need to go back and purge all of the |
| 5211 | // entries for the scalars that use the symbolic expression. |
| 5212 | forgetSymbolicName(PN, SymbolicName); |
| 5213 | ValueExprMap[SCEVCallbackVH(PN, this)] = PHISCEV; |
| 5214 | |
| 5215 | // We can add Flags to the post-inc expression only if we |
| 5216 | // know that it is *undefined behavior* for BEValueV to |
| 5217 | // overflow. |
| 5218 | if (auto *BEInst = dyn_cast<Instruction>(BEValueV)) |
| 5219 | if (isLoopInvariant(Accum, L) && isAddRecNeverPoison(BEInst, L)) |
| 5220 | (void)getAddRecExpr(getAddExpr(StartVal, Accum), Accum, L, Flags); |
| 5221 | |
| 5222 | return PHISCEV; |
| 5223 | } |
| 5224 | } |
| 5225 | } else { |
| 5226 | // Otherwise, this could be a loop like this: |
| 5227 | // i = 0; for (j = 1; ..; ++j) { .... i = j; } |
| 5228 | // In this case, j = {1,+,1} and BEValue is j. |
| 5229 | // Because the other in-value of i (0) fits the evolution of BEValue |
| 5230 | // i really is an addrec evolution. |
| 5231 | // |
| 5232 | // We can generalize this saying that i is the shifted value of BEValue |
| 5233 | // by one iteration: |
| 5234 | // PHI(f(0), f({1,+,1})) --> f({0,+,1}) |
| 5235 | const SCEV *Shifted = SCEVShiftRewriter::rewrite(BEValue, L, *this); |
| 5236 | const SCEV *Start = SCEVInitRewriter::rewrite(Shifted, L, *this, false); |
| 5237 | if (Shifted != getCouldNotCompute() && |
| 5238 | Start != getCouldNotCompute()) { |
| 5239 | const SCEV *StartVal = getSCEV(StartValueV); |
| 5240 | if (Start == StartVal) { |
| 5241 | // Okay, for the entire analysis of this edge we assumed the PHI |
| 5242 | // to be symbolic. We now need to go back and purge all of the |
| 5243 | // entries for the scalars that use the symbolic expression. |
| 5244 | forgetSymbolicName(PN, SymbolicName); |
| 5245 | ValueExprMap[SCEVCallbackVH(PN, this)] = Shifted; |
| 5246 | return Shifted; |
| 5247 | } |
| 5248 | } |
| 5249 | } |
| 5250 | |
| 5251 | // Remove the temporary PHI node SCEV that has been inserted while intending |
| 5252 | // to create an AddRecExpr for this PHI node. We can not keep this temporary |
| 5253 | // as it will prevent later (possibly simpler) SCEV expressions to be added |
| 5254 | // to the ValueExprMap. |
| 5255 | eraseValueFromMap(PN); |
| 5256 | |
| 5257 | return nullptr; |
| 5258 | } |
| 5259 | |
| 5260 | // Checks if the SCEV S is available at BB. S is considered available at BB |
| 5261 | // if S can be materialized at BB without introducing a fault. |
| 5262 | static bool IsAvailableOnEntry(const Loop *L, DominatorTree &DT, const SCEV *S, |
| 5263 | BasicBlock *BB) { |
| 5264 | struct CheckAvailable { |
| 5265 | bool TraversalDone = false; |
| 5266 | bool Available = true; |
| 5267 | |
| 5268 | const Loop *L = nullptr; // The loop BB is in (can be nullptr) |
| 5269 | BasicBlock *BB = nullptr; |
| 5270 | DominatorTree &DT; |
| 5271 | |
| 5272 | CheckAvailable(const Loop *L, BasicBlock *BB, DominatorTree &DT) |
| 5273 | : L(L), BB(BB), DT(DT) {} |
| 5274 | |
| 5275 | bool setUnavailable() { |
| 5276 | TraversalDone = true; |
| 5277 | Available = false; |
| 5278 | return false; |
| 5279 | } |
| 5280 | |
| 5281 | bool follow(const SCEV *S) { |
| 5282 | switch (S->getSCEVType()) { |
| 5283 | case scConstant: |
| 5284 | case scPtrToInt: |
| 5285 | case scTruncate: |
| 5286 | case scZeroExtend: |
| 5287 | case scSignExtend: |
| 5288 | case scAddExpr: |
| 5289 | case scMulExpr: |
| 5290 | case scUMaxExpr: |
| 5291 | case scSMaxExpr: |
| 5292 | case scUMinExpr: |
| 5293 | case scSMinExpr: |
| 5294 | // These expressions are available if their operand(s) is/are. |
| 5295 | return true; |
| 5296 | |
| 5297 | case scAddRecExpr: { |
| 5298 | // We allow add recurrences that are on the loop BB is in, or some |
| 5299 | // outer loop. This guarantees availability because the value of the |
| 5300 | // add recurrence at BB is simply the "current" value of the induction |
| 5301 | // variable. We can relax this in the future; for instance an add |
| 5302 | // recurrence on a sibling dominating loop is also available at BB. |
| 5303 | const auto *ARLoop = cast<SCEVAddRecExpr>(S)->getLoop(); |
| 5304 | if (L && (ARLoop == L || ARLoop->contains(L))) |
| 5305 | return true; |
| 5306 | |
| 5307 | return setUnavailable(); |
| 5308 | } |
| 5309 | |
| 5310 | case scUnknown: { |
| 5311 | // For SCEVUnknown, we check for simple dominance. |
| 5312 | const auto *SU = cast<SCEVUnknown>(S); |
| 5313 | Value *V = SU->getValue(); |
| 5314 | |
| 5315 | if (isa<Argument>(V)) |
| 5316 | return false; |
| 5317 | |
| 5318 | if (isa<Instruction>(V) && DT.dominates(cast<Instruction>(V), BB)) |
| 5319 | return false; |
| 5320 | |
| 5321 | return setUnavailable(); |
| 5322 | } |
| 5323 | |
| 5324 | case scUDivExpr: |
| 5325 | case scCouldNotCompute: |
| 5326 | // We do not try to smart about these at all. |
| 5327 | return setUnavailable(); |
| 5328 | } |
| 5329 | llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 5329); |
| 5330 | } |
| 5331 | |
| 5332 | bool isDone() { return TraversalDone; } |
| 5333 | }; |
| 5334 | |
| 5335 | CheckAvailable CA(L, BB, DT); |
| 5336 | SCEVTraversal<CheckAvailable> ST(CA); |
| 5337 | |
| 5338 | ST.visitAll(S); |
| 5339 | return CA.Available; |
| 5340 | } |
| 5341 | |
| 5342 | // Try to match a control flow sequence that branches out at BI and merges back |
| 5343 | // at Merge into a "C ? LHS : RHS" select pattern. Return true on a successful |
| 5344 | // match. |
| 5345 | static bool BrPHIToSelect(DominatorTree &DT, BranchInst *BI, PHINode *Merge, |
| 5346 | Value *&C, Value *&LHS, Value *&RHS) { |
| 5347 | C = BI->getCondition(); |
| 5348 | |
| 5349 | BasicBlockEdge LeftEdge(BI->getParent(), BI->getSuccessor(0)); |
| 5350 | BasicBlockEdge RightEdge(BI->getParent(), BI->getSuccessor(1)); |
| 5351 | |
| 5352 | if (!LeftEdge.isSingleEdge()) |
| 5353 | return false; |
| 5354 | |
| 5355 | assert(RightEdge.isSingleEdge() && "Follows from LeftEdge.isSingleEdge()")(static_cast <bool> (RightEdge.isSingleEdge() && "Follows from LeftEdge.isSingleEdge()") ? void (0) : __assert_fail ("RightEdge.isSingleEdge() && \"Follows from LeftEdge.isSingleEdge()\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 5355, __extension__ __PRETTY_FUNCTION__)); |
| 5356 | |
| 5357 | Use &LeftUse = Merge->getOperandUse(0); |
| 5358 | Use &RightUse = Merge->getOperandUse(1); |
| 5359 | |
| 5360 | if (DT.dominates(LeftEdge, LeftUse) && DT.dominates(RightEdge, RightUse)) { |
| 5361 | LHS = LeftUse; |
| 5362 | RHS = RightUse; |
| 5363 | return true; |
| 5364 | } |
| 5365 | |
| 5366 | if (DT.dominates(LeftEdge, RightUse) && DT.dominates(RightEdge, LeftUse)) { |
| 5367 | LHS = RightUse; |
| 5368 | RHS = LeftUse; |
| 5369 | return true; |
| 5370 | } |
| 5371 | |
| 5372 | return false; |
| 5373 | } |
| 5374 | |
| 5375 | const SCEV *ScalarEvolution::createNodeFromSelectLikePHI(PHINode *PN) { |
| 5376 | auto IsReachable = |
| 5377 | [&](BasicBlock *BB) { return DT.isReachableFromEntry(BB); }; |
| 5378 | if (PN->getNumIncomingValues() == 2 && all_of(PN->blocks(), IsReachable)) { |
| 5379 | const Loop *L = LI.getLoopFor(PN->getParent()); |
| 5380 | |
| 5381 | // We don't want to break LCSSA, even in a SCEV expression tree. |
| 5382 | for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) |
| 5383 | if (LI.getLoopFor(PN->getIncomingBlock(i)) != L) |
| 5384 | return nullptr; |
| 5385 | |
| 5386 | // Try to match |
| 5387 | // |
| 5388 | // br %cond, label %left, label %right |
| 5389 | // left: |
| 5390 | // br label %merge |
| 5391 | // right: |
| 5392 | // br label %merge |
| 5393 | // merge: |
| 5394 | // V = phi [ %x, %left ], [ %y, %right ] |
| 5395 | // |
| 5396 | // as "select %cond, %x, %y" |
| 5397 | |
| 5398 | BasicBlock *IDom = DT[PN->getParent()]->getIDom()->getBlock(); |
| 5399 | assert(IDom && "At least the entry block should dominate PN")(static_cast <bool> (IDom && "At least the entry block should dominate PN" ) ? void (0) : __assert_fail ("IDom && \"At least the entry block should dominate PN\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 5399, __extension__ __PRETTY_FUNCTION__)); |
| 5400 | |
| 5401 | auto *BI = dyn_cast<BranchInst>(IDom->getTerminator()); |
| 5402 | Value *Cond = nullptr, *LHS = nullptr, *RHS = nullptr; |
| 5403 | |
| 5404 | if (BI && BI->isConditional() && |
| 5405 | BrPHIToSelect(DT, BI, PN, Cond, LHS, RHS) && |
| 5406 | IsAvailableOnEntry(L, DT, getSCEV(LHS), PN->getParent()) && |
| 5407 | IsAvailableOnEntry(L, DT, getSCEV(RHS), PN->getParent())) |
| 5408 | return createNodeForSelectOrPHI(PN, Cond, LHS, RHS); |
| 5409 | } |
| 5410 | |
| 5411 | return nullptr; |
| 5412 | } |
| 5413 | |
| 5414 | const SCEV *ScalarEvolution::createNodeForPHI(PHINode *PN) { |
| 5415 | if (const SCEV *S = createAddRecFromPHI(PN)) |
| 5416 | return S; |
| 5417 | |
| 5418 | if (const SCEV *S = createNodeFromSelectLikePHI(PN)) |
| 5419 | return S; |
| 5420 | |
| 5421 | // If the PHI has a single incoming value, follow that value, unless the |
| 5422 | // PHI's incoming blocks are in a different loop, in which case doing so |
| 5423 | // risks breaking LCSSA form. Instcombine would normally zap these, but |
| 5424 | // it doesn't have DominatorTree information, so it may miss cases. |
| 5425 | if (Value *V = SimplifyInstruction(PN, {getDataLayout(), &TLI, &DT, &AC})) |
| 5426 | if (LI.replacementPreservesLCSSAForm(PN, V)) |
| 5427 | return getSCEV(V); |
| 5428 | |
| 5429 | // If it's not a loop phi, we can't handle it yet. |
| 5430 | return getUnknown(PN); |
| 5431 | } |
| 5432 | |
| 5433 | const SCEV *ScalarEvolution::createNodeForSelectOrPHI(Instruction *I, |
| 5434 | Value *Cond, |
| 5435 | Value *TrueVal, |
| 5436 | Value *FalseVal) { |
| 5437 | // Handle "constant" branch or select. This can occur for instance when a |
| 5438 | // loop pass transforms an inner loop and moves on to process the outer loop. |
| 5439 | if (auto *CI = dyn_cast<ConstantInt>(Cond)) |
| 5440 | return getSCEV(CI->isOne() ? TrueVal : FalseVal); |
| 5441 | |
| 5442 | // Try to match some simple smax or umax patterns. |
| 5443 | auto *ICI = dyn_cast<ICmpInst>(Cond); |
| 5444 | if (!ICI) |
| 5445 | return getUnknown(I); |
| 5446 | |
| 5447 | Value *LHS = ICI->getOperand(0); |
| 5448 | Value *RHS = ICI->getOperand(1); |
| 5449 | |
| 5450 | switch (ICI->getPredicate()) { |
| 5451 | case ICmpInst::ICMP_SLT: |
| 5452 | case ICmpInst::ICMP_SLE: |
| 5453 | std::swap(LHS, RHS); |
| 5454 | LLVM_FALLTHROUGH[[gnu::fallthrough]]; |
| 5455 | case ICmpInst::ICMP_SGT: |
| 5456 | case ICmpInst::ICMP_SGE: |
| 5457 | // a >s b ? a+x : b+x -> smax(a, b)+x |
| 5458 | // a >s b ? b+x : a+x -> smin(a, b)+x |
| 5459 | if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType())) { |
| 5460 | const SCEV *LS = getNoopOrSignExtend(getSCEV(LHS), I->getType()); |
| 5461 | const SCEV *RS = getNoopOrSignExtend(getSCEV(RHS), I->getType()); |
| 5462 | const SCEV *LA = getSCEV(TrueVal); |
| 5463 | const SCEV *RA = getSCEV(FalseVal); |
| 5464 | const SCEV *LDiff = getMinusSCEV(LA, LS); |
| 5465 | const SCEV *RDiff = getMinusSCEV(RA, RS); |
| 5466 | if (LDiff == RDiff) |
| 5467 | return getAddExpr(getSMaxExpr(LS, RS), LDiff); |
| 5468 | LDiff = getMinusSCEV(LA, RS); |
| 5469 | RDiff = getMinusSCEV(RA, LS); |
| 5470 | if (LDiff == RDiff) |
| 5471 | return getAddExpr(getSMinExpr(LS, RS), LDiff); |
| 5472 | } |
| 5473 | break; |
| 5474 | case ICmpInst::ICMP_ULT: |
| 5475 | case ICmpInst::ICMP_ULE: |
| 5476 | std::swap(LHS, RHS); |
| 5477 | LLVM_FALLTHROUGH[[gnu::fallthrough]]; |
| 5478 | case ICmpInst::ICMP_UGT: |
| 5479 | case ICmpInst::ICMP_UGE: |
| 5480 | // a >u b ? a+x : b+x -> umax(a, b)+x |
| 5481 | // a >u b ? b+x : a+x -> umin(a, b)+x |
| 5482 | if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType())) { |
| 5483 | const SCEV *LS = getNoopOrZeroExtend(getSCEV(LHS), I->getType()); |
| 5484 | const SCEV *RS = getNoopOrZeroExtend(getSCEV(RHS), I->getType()); |
| 5485 | const SCEV *LA = getSCEV(TrueVal); |
| 5486 | const SCEV *RA = getSCEV(FalseVal); |
| 5487 | const SCEV *LDiff = getMinusSCEV(LA, LS); |
| 5488 | const SCEV *RDiff = getMinusSCEV(RA, RS); |
| 5489 | if (LDiff == RDiff) |
| 5490 | return getAddExpr(getUMaxExpr(LS, RS), LDiff); |
| 5491 | LDiff = getMinusSCEV(LA, RS); |
| 5492 | RDiff = getMinusSCEV(RA, LS); |
| 5493 | if (LDiff == RDiff) |
| 5494 | return getAddExpr(getUMinExpr(LS, RS), LDiff); |
| 5495 | } |
| 5496 | break; |
| 5497 | case ICmpInst::ICMP_NE: |
| 5498 | // n != 0 ? n+x : 1+x -> umax(n, 1)+x |
| 5499 | if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType()) && |
| 5500 | isa<ConstantInt>(RHS) && cast<ConstantInt>(RHS)->isZero()) { |
| 5501 | const SCEV *One = getOne(I->getType()); |
| 5502 | const SCEV *LS = getNoopOrZeroExtend(getSCEV(LHS), I->getType()); |
| 5503 | const SCEV *LA = getSCEV(TrueVal); |
| 5504 | const SCEV *RA = getSCEV(FalseVal); |
| 5505 | const SCEV *LDiff = getMinusSCEV(LA, LS); |
| 5506 | const SCEV *RDiff = getMinusSCEV(RA, One); |
| 5507 | if (LDiff == RDiff) |
| 5508 | return getAddExpr(getUMaxExpr(One, LS), LDiff); |
| 5509 | } |
| 5510 | break; |
| 5511 | case ICmpInst::ICMP_EQ: |
| 5512 | // n == 0 ? 1+x : n+x -> umax(n, 1)+x |
| 5513 | if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType()) && |
| 5514 | isa<ConstantInt>(RHS) && cast<ConstantInt>(RHS)->isZero()) { |
| 5515 | const SCEV *One = getOne(I->getType()); |
| 5516 | const SCEV *LS = getNoopOrZeroExtend(getSCEV(LHS), I->getType()); |
| 5517 | const SCEV *LA = getSCEV(TrueVal); |
| 5518 | const SCEV *RA = getSCEV(FalseVal); |
| 5519 | const SCEV *LDiff = getMinusSCEV(LA, One); |
| 5520 | const SCEV *RDiff = getMinusSCEV(RA, LS); |
| 5521 | if (LDiff == RDiff) |
| 5522 | return getAddExpr(getUMaxExpr(One, LS), LDiff); |
| 5523 | } |
| 5524 | break; |
| 5525 | default: |
| 5526 | break; |
| 5527 | } |
| 5528 | |
| 5529 | return getUnknown(I); |
| 5530 | } |
| 5531 | |
| 5532 | /// Expand GEP instructions into add and multiply operations. This allows them |
| 5533 | /// to be analyzed by regular SCEV code. |
| 5534 | const SCEV *ScalarEvolution::createNodeForGEP(GEPOperator *GEP) { |
| 5535 | // Don't attempt to analyze GEPs over unsized objects. |
| 5536 | if (!GEP->getSourceElementType()->isSized()) |
| 5537 | return getUnknown(GEP); |
| 5538 | |
| 5539 | SmallVector<const SCEV *, 4> IndexExprs; |
| 5540 | for (auto Index = GEP->idx_begin(); Index != GEP->idx_end(); ++Index) |
| 5541 | IndexExprs.push_back(getSCEV(*Index)); |
| 5542 | return getGEPExpr(GEP, IndexExprs); |
| 5543 | } |
| 5544 | |
| 5545 | uint32_t ScalarEvolution::GetMinTrailingZerosImpl(const SCEV *S) { |
| 5546 | if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S)) |
| 5547 | return C->getAPInt().countTrailingZeros(); |
| 5548 | |
| 5549 | if (const SCEVPtrToIntExpr *I = dyn_cast<SCEVPtrToIntExpr>(S)) |
| 5550 | return GetMinTrailingZeros(I->getOperand()); |
| 5551 | |
| 5552 | if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(S)) |
| 5553 | return std::min(GetMinTrailingZeros(T->getOperand()), |
| 5554 | (uint32_t)getTypeSizeInBits(T->getType())); |
| 5555 | |
| 5556 | if (const SCEVZeroExtendExpr *E = dyn_cast<SCEVZeroExtendExpr>(S)) { |
| 5557 | uint32_t OpRes = GetMinTrailingZeros(E->getOperand()); |
| 5558 | return OpRes == getTypeSizeInBits(E->getOperand()->getType()) |
| 5559 | ? getTypeSizeInBits(E->getType()) |
| 5560 | : OpRes; |
| 5561 | } |
| 5562 | |
| 5563 | if (const SCEVSignExtendExpr *E = dyn_cast<SCEVSignExtendExpr>(S)) { |
| 5564 | uint32_t OpRes = GetMinTrailingZeros(E->getOperand()); |
| 5565 | return OpRes == getTypeSizeInBits(E->getOperand()->getType()) |
| 5566 | ? getTypeSizeInBits(E->getType()) |
| 5567 | : OpRes; |
| 5568 | } |
| 5569 | |
| 5570 | if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(S)) { |
| 5571 | // The result is the min of all operands results. |
| 5572 | uint32_t MinOpRes = GetMinTrailingZeros(A->getOperand(0)); |
| 5573 | for (unsigned i = 1, e = A->getNumOperands(); MinOpRes && i != e; ++i) |
| 5574 | MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(A->getOperand(i))); |
| 5575 | return MinOpRes; |
| 5576 | } |
| 5577 | |
| 5578 | if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(S)) { |
| 5579 | // The result is the sum of all operands results. |
| 5580 | uint32_t SumOpRes = GetMinTrailingZeros(M->getOperand(0)); |
| 5581 | uint32_t BitWidth = getTypeSizeInBits(M->getType()); |
| 5582 | for (unsigned i = 1, e = M->getNumOperands(); |
| 5583 | SumOpRes != BitWidth && i != e; ++i) |
| 5584 | SumOpRes = |
| 5585 | std::min(SumOpRes + GetMinTrailingZeros(M->getOperand(i)), BitWidth); |
| 5586 | return SumOpRes; |
| 5587 | } |
| 5588 | |
| 5589 | if (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(S)) { |
| 5590 | // The result is the min of all operands results. |
| 5591 | uint32_t MinOpRes = GetMinTrailingZeros(A->getOperand(0)); |
| 5592 | for (unsigned i = 1, e = A->getNumOperands(); MinOpRes && i != e; ++i) |
| 5593 | MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(A->getOperand(i))); |
| 5594 | return MinOpRes; |
| 5595 | } |
| 5596 | |
| 5597 | if (const SCEVSMaxExpr *M = dyn_cast<SCEVSMaxExpr>(S)) { |
| 5598 | // The result is the min of all operands results. |
| 5599 | uint32_t MinOpRes = GetMinTrailingZeros(M->getOperand(0)); |
| 5600 | for (unsigned i = 1, e = M->getNumOperands(); MinOpRes && i != e; ++i) |
| 5601 | MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(M->getOperand(i))); |
| 5602 | return MinOpRes; |
| 5603 | } |
| 5604 | |
| 5605 | if (const SCEVUMaxExpr *M = dyn_cast<SCEVUMaxExpr>(S)) { |
| 5606 | // The result is the min of all operands results. |
| 5607 | uint32_t MinOpRes = GetMinTrailingZeros(M->getOperand(0)); |
| 5608 | for (unsigned i = 1, e = M->getNumOperands(); MinOpRes && i != e; ++i) |
| 5609 | MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(M->getOperand(i))); |
| 5610 | return MinOpRes; |
| 5611 | } |
| 5612 | |
| 5613 | if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) { |
| 5614 | // For a SCEVUnknown, ask ValueTracking. |
| 5615 | KnownBits Known = computeKnownBits(U->getValue(), getDataLayout(), 0, &AC, nullptr, &DT); |
| 5616 | return Known.countMinTrailingZeros(); |
| 5617 | } |
| 5618 | |
| 5619 | // SCEVUDivExpr |
| 5620 | return 0; |
| 5621 | } |
| 5622 | |
| 5623 | uint32_t ScalarEvolution::GetMinTrailingZeros(const SCEV *S) { |
| 5624 | auto I = MinTrailingZerosCache.find(S); |
| 5625 | if (I != MinTrailingZerosCache.end()) |
| 5626 | return I->second; |
| 5627 | |
| 5628 | uint32_t Result = GetMinTrailingZerosImpl(S); |
| 5629 | auto InsertPair = MinTrailingZerosCache.insert({S, Result}); |
| 5630 | assert(InsertPair.second && "Should insert a new key")(static_cast <bool> (InsertPair.second && "Should insert a new key" ) ? void (0) : __assert_fail ("InsertPair.second && \"Should insert a new key\"" , "/build/llvm-toolchain-snapshot-13~++20210506100649+6304c0836a4d/llvm/lib/Analysis/ScalarEvolution.cpp" , 5630, __extension__ __PRETTY_FUNCTION__)); |
| 5631 | return InsertPair.first->second; |
| 5632 | } |
| 5633 | |
| 5634 | /// Helper method to assign a range to V from metadata present in the IR. |
| 5635 | static Optional<ConstantRange> GetRangeFromMetadata(Value *V) { |
| 5636 | if (Instruction *I = dyn_cast<Instruction>(V)) |
| 5637 | if (MDNode *MD = I->getMetadata(LLVMContext::MD_range)) |
| 5638 | return getConstantRangeFromMetadata(*MD); |
| 5639 | |
| 5640 | return None; |
| 5641 | } |
| 5642 | |
| 5643 | void ScalarEvolution::setNoWrapFlags(SCEVAddRecExpr *AddRec, |
| 5644 | SCEV::NoWrapFlags Flags) { |
| 5645 | if (AddRec->getNoWrapFlags(Flags) != Flags) { |
| 5646 | AddRec->setNoWrapFlags(Flags); |
| 5647 | UnsignedRanges.erase(AddRec); |
| 5648 | SignedRanges.erase(AddRec); |
| 5649 | } |
| 5650 | } |
| 5651 | |
| 5652 | ConstantRange ScalarEvolution:: |
| 5653 | getRangeForUnknownRecurrence(const SCEVUnknown *U) { |
| 5654 | const DataLayout &DL = getDataLayout(); |
| 5655 | |
| 5656 | unsigned BitWidth = getTypeSizeInBits(U->getType()); |
| 5657 | const ConstantRange FullSet(BitWidth, /*isFullSet=*/true); |
| 5658 | |
| 5659 | // Match a simple recurrence of the form: <start, ShiftOp, Step>, and then |
| 5660 | // use information about the trip count to improve our available range. Note |
| 5661 | // that the trip count independent cases are already handled by known bits. |
| 5662 | // WARNING: The definition of recurrence used here is subtly different than |
| 5663 | // the one used by AddRec (and thus most of this file). Step is allowed to |
| 5664 | // be arbitrarily loop varying here, where AddRec allows only loop invariant |
| 5665 | // and other addrecs in the same loop (for non-affine addrecs). The code |
| 5666 | // below intentionally handles the case where step is not loop invariant. |
| 5667 | auto *P = dyn_cast<PHINode>(U->getValue()); |
| 5668 | if (!P) |
| 5669 | return FullSet; |
| 5670 | |
| 5671 | // Make sure that no Phi input comes from an unreachable block. Otherwise, |
| 5672 | // even the values that are not available in these blocks may come from them, |
| 5673 | // and this leads to false-positive recurrence test. |
| 5674 | for (auto *Pred : predecessors(P->getParent())) |
| 5675 | if (!DT.isReachableFromEntry(Pred)) |
| 5676 | return FullSet; |
| 5677 | |
| 5678 | BinaryOperator *BO; |
| 5679 | Value *Start, *Step; |
| 5680 | if (!matchSimpleRecurrence(P, BO, Start, Step)) |
| 5681 | return FullSet; |
| 5682 | |
| 5683 | // If we found a recurrence in reachable code, we must be in a loop. Note |
| 5684 | // that BO might be in some subloop of L, and that's completely okay. |
| 5685 | auto *L = LI.getLoopFor(P->getParent()); |
| 5686 | assert(L && L->getHeader( |