| File: | lib/Transforms/Scalar/LoopRerollPass.cpp |
| Warning: | line 470, column 18 Called C++ object pointer is null |
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| 1 | //===- LoopReroll.cpp - Loop rerolling pass -------------------------------===// | ||||
| 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 pass implements a simple loop reroller. | ||||
| 10 | // | ||||
| 11 | //===----------------------------------------------------------------------===// | ||||
| 12 | |||||
| 13 | #include "llvm/ADT/APInt.h" | ||||
| 14 | #include "llvm/ADT/BitVector.h" | ||||
| 15 | #include "llvm/ADT/DenseMap.h" | ||||
| 16 | #include "llvm/ADT/DenseSet.h" | ||||
| 17 | #include "llvm/ADT/MapVector.h" | ||||
| 18 | #include "llvm/ADT/STLExtras.h" | ||||
| 19 | #include "llvm/ADT/SmallPtrSet.h" | ||||
| 20 | #include "llvm/ADT/SmallVector.h" | ||||
| 21 | #include "llvm/ADT/Statistic.h" | ||||
| 22 | #include "llvm/Analysis/AliasAnalysis.h" | ||||
| 23 | #include "llvm/Analysis/AliasSetTracker.h" | ||||
| 24 | #include "llvm/Analysis/LoopInfo.h" | ||||
| 25 | #include "llvm/Analysis/LoopPass.h" | ||||
| 26 | #include "llvm/Analysis/ScalarEvolution.h" | ||||
| 27 | #include "llvm/Analysis/ScalarEvolutionExpander.h" | ||||
| 28 | #include "llvm/Analysis/ScalarEvolutionExpressions.h" | ||||
| 29 | #include "llvm/Analysis/TargetLibraryInfo.h" | ||||
| 30 | #include "llvm/Transforms/Utils/Local.h" | ||||
| 31 | #include "llvm/Analysis/ValueTracking.h" | ||||
| 32 | #include "llvm/IR/BasicBlock.h" | ||||
| 33 | #include "llvm/IR/Constants.h" | ||||
| 34 | #include "llvm/IR/DataLayout.h" | ||||
| 35 | #include "llvm/IR/DerivedTypes.h" | ||||
| 36 | #include "llvm/IR/Dominators.h" | ||||
| 37 | #include "llvm/IR/IRBuilder.h" | ||||
| 38 | #include "llvm/IR/InstrTypes.h" | ||||
| 39 | #include "llvm/IR/Instruction.h" | ||||
| 40 | #include "llvm/IR/Instructions.h" | ||||
| 41 | #include "llvm/IR/IntrinsicInst.h" | ||||
| 42 | #include "llvm/IR/Intrinsics.h" | ||||
| 43 | #include "llvm/IR/Module.h" | ||||
| 44 | #include "llvm/IR/Type.h" | ||||
| 45 | #include "llvm/IR/Use.h" | ||||
| 46 | #include "llvm/IR/User.h" | ||||
| 47 | #include "llvm/IR/Value.h" | ||||
| 48 | #include "llvm/Pass.h" | ||||
| 49 | #include "llvm/Support/Casting.h" | ||||
| 50 | #include "llvm/Support/CommandLine.h" | ||||
| 51 | #include "llvm/Support/Debug.h" | ||||
| 52 | #include "llvm/Support/raw_ostream.h" | ||||
| 53 | #include "llvm/Transforms/Scalar.h" | ||||
| 54 | #include "llvm/Transforms/Utils.h" | ||||
| 55 | #include "llvm/Transforms/Utils/BasicBlockUtils.h" | ||||
| 56 | #include "llvm/Transforms/Utils/LoopUtils.h" | ||||
| 57 | #include <cassert> | ||||
| 58 | #include <cstddef> | ||||
| 59 | #include <cstdint> | ||||
| 60 | #include <cstdlib> | ||||
| 61 | #include <iterator> | ||||
| 62 | #include <map> | ||||
| 63 | #include <utility> | ||||
| 64 | |||||
| 65 | using namespace llvm; | ||||
| 66 | |||||
| 67 | #define DEBUG_TYPE"loop-reroll" "loop-reroll" | ||||
| 68 | |||||
| 69 | STATISTIC(NumRerolledLoops, "Number of rerolled loops")static llvm::Statistic NumRerolledLoops = {"loop-reroll", "NumRerolledLoops" , "Number of rerolled loops"}; | ||||
| 70 | |||||
| 71 | static cl::opt<unsigned> | ||||
| 72 | NumToleratedFailedMatches("reroll-num-tolerated-failed-matches", cl::init(400), | ||||
| 73 | cl::Hidden, | ||||
| 74 | cl::desc("The maximum number of failures to tolerate" | ||||
| 75 | " during fuzzy matching. (default: 400)")); | ||||
| 76 | |||||
| 77 | // This loop re-rolling transformation aims to transform loops like this: | ||||
| 78 | // | ||||
| 79 | // int foo(int a); | ||||
| 80 | // void bar(int *x) { | ||||
| 81 | // for (int i = 0; i < 500; i += 3) { | ||||
| 82 | // foo(i); | ||||
| 83 | // foo(i+1); | ||||
| 84 | // foo(i+2); | ||||
| 85 | // } | ||||
| 86 | // } | ||||
| 87 | // | ||||
| 88 | // into a loop like this: | ||||
| 89 | // | ||||
| 90 | // void bar(int *x) { | ||||
| 91 | // for (int i = 0; i < 500; ++i) | ||||
| 92 | // foo(i); | ||||
| 93 | // } | ||||
| 94 | // | ||||
| 95 | // It does this by looking for loops that, besides the latch code, are composed | ||||
| 96 | // of isomorphic DAGs of instructions, with each DAG rooted at some increment | ||||
| 97 | // to the induction variable, and where each DAG is isomorphic to the DAG | ||||
| 98 | // rooted at the induction variable (excepting the sub-DAGs which root the | ||||
| 99 | // other induction-variable increments). In other words, we're looking for loop | ||||
| 100 | // bodies of the form: | ||||
| 101 | // | ||||
| 102 | // %iv = phi [ (preheader, ...), (body, %iv.next) ] | ||||
| 103 | // f(%iv) | ||||
| 104 | // %iv.1 = add %iv, 1 <-- a root increment | ||||
| 105 | // f(%iv.1) | ||||
| 106 | // %iv.2 = add %iv, 2 <-- a root increment | ||||
| 107 | // f(%iv.2) | ||||
| 108 | // %iv.scale_m_1 = add %iv, scale-1 <-- a root increment | ||||
| 109 | // f(%iv.scale_m_1) | ||||
| 110 | // ... | ||||
| 111 | // %iv.next = add %iv, scale | ||||
| 112 | // %cmp = icmp(%iv, ...) | ||||
| 113 | // br %cmp, header, exit | ||||
| 114 | // | ||||
| 115 | // where each f(i) is a set of instructions that, collectively, are a function | ||||
| 116 | // only of i (and other loop-invariant values). | ||||
| 117 | // | ||||
| 118 | // As a special case, we can also reroll loops like this: | ||||
| 119 | // | ||||
| 120 | // int foo(int); | ||||
| 121 | // void bar(int *x) { | ||||
| 122 | // for (int i = 0; i < 500; ++i) { | ||||
| 123 | // x[3*i] = foo(0); | ||||
| 124 | // x[3*i+1] = foo(0); | ||||
| 125 | // x[3*i+2] = foo(0); | ||||
| 126 | // } | ||||
| 127 | // } | ||||
| 128 | // | ||||
| 129 | // into this: | ||||
| 130 | // | ||||
| 131 | // void bar(int *x) { | ||||
| 132 | // for (int i = 0; i < 1500; ++i) | ||||
| 133 | // x[i] = foo(0); | ||||
| 134 | // } | ||||
| 135 | // | ||||
| 136 | // in which case, we're looking for inputs like this: | ||||
| 137 | // | ||||
| 138 | // %iv = phi [ (preheader, ...), (body, %iv.next) ] | ||||
| 139 | // %scaled.iv = mul %iv, scale | ||||
| 140 | // f(%scaled.iv) | ||||
| 141 | // %scaled.iv.1 = add %scaled.iv, 1 | ||||
| 142 | // f(%scaled.iv.1) | ||||
| 143 | // %scaled.iv.2 = add %scaled.iv, 2 | ||||
| 144 | // f(%scaled.iv.2) | ||||
| 145 | // %scaled.iv.scale_m_1 = add %scaled.iv, scale-1 | ||||
| 146 | // f(%scaled.iv.scale_m_1) | ||||
| 147 | // ... | ||||
| 148 | // %iv.next = add %iv, 1 | ||||
| 149 | // %cmp = icmp(%iv, ...) | ||||
| 150 | // br %cmp, header, exit | ||||
| 151 | |||||
| 152 | namespace { | ||||
| 153 | |||||
| 154 | enum IterationLimits { | ||||
| 155 | /// The maximum number of iterations that we'll try and reroll. | ||||
| 156 | IL_MaxRerollIterations = 32, | ||||
| 157 | /// The bitvector index used by loop induction variables and other | ||||
| 158 | /// instructions that belong to all iterations. | ||||
| 159 | IL_All, | ||||
| 160 | IL_End | ||||
| 161 | }; | ||||
| 162 | |||||
| 163 | class LoopReroll : public LoopPass { | ||||
| 164 | public: | ||||
| 165 | static char ID; // Pass ID, replacement for typeid | ||||
| 166 | |||||
| 167 | LoopReroll() : LoopPass(ID) { | ||||
| 168 | initializeLoopRerollPass(*PassRegistry::getPassRegistry()); | ||||
| 169 | } | ||||
| 170 | |||||
| 171 | bool runOnLoop(Loop *L, LPPassManager &LPM) override; | ||||
| 172 | |||||
| 173 | void getAnalysisUsage(AnalysisUsage &AU) const override { | ||||
| 174 | AU.addRequired<TargetLibraryInfoWrapperPass>(); | ||||
| 175 | getLoopAnalysisUsage(AU); | ||||
| 176 | } | ||||
| 177 | |||||
| 178 | protected: | ||||
| 179 | AliasAnalysis *AA; | ||||
| 180 | LoopInfo *LI; | ||||
| 181 | ScalarEvolution *SE; | ||||
| 182 | TargetLibraryInfo *TLI; | ||||
| 183 | DominatorTree *DT; | ||||
| 184 | bool PreserveLCSSA; | ||||
| 185 | |||||
| 186 | using SmallInstructionVector = SmallVector<Instruction *, 16>; | ||||
| 187 | using SmallInstructionSet = SmallPtrSet<Instruction *, 16>; | ||||
| 188 | |||||
| 189 | // Map between induction variable and its increment | ||||
| 190 | DenseMap<Instruction *, int64_t> IVToIncMap; | ||||
| 191 | |||||
| 192 | // For loop with multiple induction variable, remember the one used only to | ||||
| 193 | // control the loop. | ||||
| 194 | Instruction *LoopControlIV; | ||||
| 195 | |||||
| 196 | // A chain of isomorphic instructions, identified by a single-use PHI | ||||
| 197 | // representing a reduction. Only the last value may be used outside the | ||||
| 198 | // loop. | ||||
| 199 | struct SimpleLoopReduction { | ||||
| 200 | SimpleLoopReduction(Instruction *P, Loop *L) : Instructions(1, P) { | ||||
| 201 | assert(isa<PHINode>(P) && "First reduction instruction must be a PHI")((isa<PHINode>(P) && "First reduction instruction must be a PHI" ) ? static_cast<void> (0) : __assert_fail ("isa<PHINode>(P) && \"First reduction instruction must be a PHI\"" , "/build/llvm-toolchain-snapshot-10~svn374814/lib/Transforms/Scalar/LoopRerollPass.cpp" , 201, __PRETTY_FUNCTION__)); | ||||
| 202 | add(L); | ||||
| 203 | } | ||||
| 204 | |||||
| 205 | bool valid() const { | ||||
| 206 | return Valid; | ||||
| 207 | } | ||||
| 208 | |||||
| 209 | Instruction *getPHI() const { | ||||
| 210 | assert(Valid && "Using invalid reduction")((Valid && "Using invalid reduction") ? static_cast< void> (0) : __assert_fail ("Valid && \"Using invalid reduction\"" , "/build/llvm-toolchain-snapshot-10~svn374814/lib/Transforms/Scalar/LoopRerollPass.cpp" , 210, __PRETTY_FUNCTION__)); | ||||
| 211 | return Instructions.front(); | ||||
| 212 | } | ||||
| 213 | |||||
| 214 | Instruction *getReducedValue() const { | ||||
| 215 | assert(Valid && "Using invalid reduction")((Valid && "Using invalid reduction") ? static_cast< void> (0) : __assert_fail ("Valid && \"Using invalid reduction\"" , "/build/llvm-toolchain-snapshot-10~svn374814/lib/Transforms/Scalar/LoopRerollPass.cpp" , 215, __PRETTY_FUNCTION__)); | ||||
| 216 | return Instructions.back(); | ||||
| 217 | } | ||||
| 218 | |||||
| 219 | Instruction *get(size_t i) const { | ||||
| 220 | assert(Valid && "Using invalid reduction")((Valid && "Using invalid reduction") ? static_cast< void> (0) : __assert_fail ("Valid && \"Using invalid reduction\"" , "/build/llvm-toolchain-snapshot-10~svn374814/lib/Transforms/Scalar/LoopRerollPass.cpp" , 220, __PRETTY_FUNCTION__)); | ||||
| 221 | return Instructions[i+1]; | ||||
| 222 | } | ||||
| 223 | |||||
| 224 | Instruction *operator [] (size_t i) const { return get(i); } | ||||
| 225 | |||||
| 226 | // The size, ignoring the initial PHI. | ||||
| 227 | size_t size() const { | ||||
| 228 | assert(Valid && "Using invalid reduction")((Valid && "Using invalid reduction") ? static_cast< void> (0) : __assert_fail ("Valid && \"Using invalid reduction\"" , "/build/llvm-toolchain-snapshot-10~svn374814/lib/Transforms/Scalar/LoopRerollPass.cpp" , 228, __PRETTY_FUNCTION__)); | ||||
| 229 | return Instructions.size()-1; | ||||
| 230 | } | ||||
| 231 | |||||
| 232 | using iterator = SmallInstructionVector::iterator; | ||||
| 233 | using const_iterator = SmallInstructionVector::const_iterator; | ||||
| 234 | |||||
| 235 | iterator begin() { | ||||
| 236 | assert(Valid && "Using invalid reduction")((Valid && "Using invalid reduction") ? static_cast< void> (0) : __assert_fail ("Valid && \"Using invalid reduction\"" , "/build/llvm-toolchain-snapshot-10~svn374814/lib/Transforms/Scalar/LoopRerollPass.cpp" , 236, __PRETTY_FUNCTION__)); | ||||
| 237 | return std::next(Instructions.begin()); | ||||
| 238 | } | ||||
| 239 | |||||
| 240 | const_iterator begin() const { | ||||
| 241 | assert(Valid && "Using invalid reduction")((Valid && "Using invalid reduction") ? static_cast< void> (0) : __assert_fail ("Valid && \"Using invalid reduction\"" , "/build/llvm-toolchain-snapshot-10~svn374814/lib/Transforms/Scalar/LoopRerollPass.cpp" , 241, __PRETTY_FUNCTION__)); | ||||
| 242 | return std::next(Instructions.begin()); | ||||
| 243 | } | ||||
| 244 | |||||
| 245 | iterator end() { return Instructions.end(); } | ||||
| 246 | const_iterator end() const { return Instructions.end(); } | ||||
| 247 | |||||
| 248 | protected: | ||||
| 249 | bool Valid = false; | ||||
| 250 | SmallInstructionVector Instructions; | ||||
| 251 | |||||
| 252 | void add(Loop *L); | ||||
| 253 | }; | ||||
| 254 | |||||
| 255 | // The set of all reductions, and state tracking of possible reductions | ||||
| 256 | // during loop instruction processing. | ||||
| 257 | struct ReductionTracker { | ||||
| 258 | using SmallReductionVector = SmallVector<SimpleLoopReduction, 16>; | ||||
| 259 | |||||
| 260 | // Add a new possible reduction. | ||||
| 261 | void addSLR(SimpleLoopReduction &SLR) { PossibleReds.push_back(SLR); } | ||||
| 262 | |||||
| 263 | // Setup to track possible reductions corresponding to the provided | ||||
| 264 | // rerolling scale. Only reductions with a number of non-PHI instructions | ||||
| 265 | // that is divisible by the scale are considered. Three instructions sets | ||||
| 266 | // are filled in: | ||||
| 267 | // - A set of all possible instructions in eligible reductions. | ||||
| 268 | // - A set of all PHIs in eligible reductions | ||||
| 269 | // - A set of all reduced values (last instructions) in eligible | ||||
| 270 | // reductions. | ||||
| 271 | void restrictToScale(uint64_t Scale, | ||||
| 272 | SmallInstructionSet &PossibleRedSet, | ||||
| 273 | SmallInstructionSet &PossibleRedPHISet, | ||||
| 274 | SmallInstructionSet &PossibleRedLastSet) { | ||||
| 275 | PossibleRedIdx.clear(); | ||||
| 276 | PossibleRedIter.clear(); | ||||
| 277 | Reds.clear(); | ||||
| 278 | |||||
| 279 | for (unsigned i = 0, e = PossibleReds.size(); i != e; ++i) | ||||
| 280 | if (PossibleReds[i].size() % Scale == 0) { | ||||
| 281 | PossibleRedLastSet.insert(PossibleReds[i].getReducedValue()); | ||||
| 282 | PossibleRedPHISet.insert(PossibleReds[i].getPHI()); | ||||
| 283 | |||||
| 284 | PossibleRedSet.insert(PossibleReds[i].getPHI()); | ||||
| 285 | PossibleRedIdx[PossibleReds[i].getPHI()] = i; | ||||
| 286 | for (Instruction *J : PossibleReds[i]) { | ||||
| 287 | PossibleRedSet.insert(J); | ||||
| 288 | PossibleRedIdx[J] = i; | ||||
| 289 | } | ||||
| 290 | } | ||||
| 291 | } | ||||
| 292 | |||||
| 293 | // The functions below are used while processing the loop instructions. | ||||
| 294 | |||||
| 295 | // Are the two instructions both from reductions, and furthermore, from | ||||
| 296 | // the same reduction? | ||||
| 297 | bool isPairInSame(Instruction *J1, Instruction *J2) { | ||||
| 298 | DenseMap<Instruction *, int>::iterator J1I = PossibleRedIdx.find(J1); | ||||
| 299 | if (J1I != PossibleRedIdx.end()) { | ||||
| 300 | DenseMap<Instruction *, int>::iterator J2I = PossibleRedIdx.find(J2); | ||||
| 301 | if (J2I != PossibleRedIdx.end() && J1I->second == J2I->second) | ||||
| 302 | return true; | ||||
| 303 | } | ||||
| 304 | |||||
| 305 | return false; | ||||
| 306 | } | ||||
| 307 | |||||
| 308 | // The two provided instructions, the first from the base iteration, and | ||||
| 309 | // the second from iteration i, form a matched pair. If these are part of | ||||
| 310 | // a reduction, record that fact. | ||||
| 311 | void recordPair(Instruction *J1, Instruction *J2, unsigned i) { | ||||
| 312 | if (PossibleRedIdx.count(J1)) { | ||||
| 313 | assert(PossibleRedIdx.count(J2) &&((PossibleRedIdx.count(J2) && "Recording reduction vs. non-reduction instruction?" ) ? static_cast<void> (0) : __assert_fail ("PossibleRedIdx.count(J2) && \"Recording reduction vs. non-reduction instruction?\"" , "/build/llvm-toolchain-snapshot-10~svn374814/lib/Transforms/Scalar/LoopRerollPass.cpp" , 314, __PRETTY_FUNCTION__)) | ||||
| 314 | "Recording reduction vs. non-reduction instruction?")((PossibleRedIdx.count(J2) && "Recording reduction vs. non-reduction instruction?" ) ? static_cast<void> (0) : __assert_fail ("PossibleRedIdx.count(J2) && \"Recording reduction vs. non-reduction instruction?\"" , "/build/llvm-toolchain-snapshot-10~svn374814/lib/Transforms/Scalar/LoopRerollPass.cpp" , 314, __PRETTY_FUNCTION__)); | ||||
| 315 | |||||
| 316 | PossibleRedIter[J1] = 0; | ||||
| 317 | PossibleRedIter[J2] = i; | ||||
| 318 | |||||
| 319 | int Idx = PossibleRedIdx[J1]; | ||||
| 320 | assert(Idx == PossibleRedIdx[J2] &&((Idx == PossibleRedIdx[J2] && "Recording pair from different reductions?" ) ? static_cast<void> (0) : __assert_fail ("Idx == PossibleRedIdx[J2] && \"Recording pair from different reductions?\"" , "/build/llvm-toolchain-snapshot-10~svn374814/lib/Transforms/Scalar/LoopRerollPass.cpp" , 321, __PRETTY_FUNCTION__)) | ||||
| 321 | "Recording pair from different reductions?")((Idx == PossibleRedIdx[J2] && "Recording pair from different reductions?" ) ? static_cast<void> (0) : __assert_fail ("Idx == PossibleRedIdx[J2] && \"Recording pair from different reductions?\"" , "/build/llvm-toolchain-snapshot-10~svn374814/lib/Transforms/Scalar/LoopRerollPass.cpp" , 321, __PRETTY_FUNCTION__)); | ||||
| 322 | Reds.insert(Idx); | ||||
| 323 | } | ||||
| 324 | } | ||||
| 325 | |||||
| 326 | // The functions below can be called after we've finished processing all | ||||
| 327 | // instructions in the loop, and we know which reductions were selected. | ||||
| 328 | |||||
| 329 | bool validateSelected(); | ||||
| 330 | void replaceSelected(); | ||||
| 331 | |||||
| 332 | protected: | ||||
| 333 | // The vector of all possible reductions (for any scale). | ||||
| 334 | SmallReductionVector PossibleReds; | ||||
| 335 | |||||
| 336 | DenseMap<Instruction *, int> PossibleRedIdx; | ||||
| 337 | DenseMap<Instruction *, int> PossibleRedIter; | ||||
| 338 | DenseSet<int> Reds; | ||||
| 339 | }; | ||||
| 340 | |||||
| 341 | // A DAGRootSet models an induction variable being used in a rerollable | ||||
| 342 | // loop. For example, | ||||
| 343 | // | ||||
| 344 | // x[i*3+0] = y1 | ||||
| 345 | // x[i*3+1] = y2 | ||||
| 346 | // x[i*3+2] = y3 | ||||
| 347 | // | ||||
| 348 | // Base instruction -> i*3 | ||||
| 349 | // +---+----+ | ||||
| 350 | // / | \ | ||||
| 351 | // ST[y1] +1 +2 <-- Roots | ||||
| 352 | // | | | ||||
| 353 | // ST[y2] ST[y3] | ||||
| 354 | // | ||||
| 355 | // There may be multiple DAGRoots, for example: | ||||
| 356 | // | ||||
| 357 | // x[i*2+0] = ... (1) | ||||
| 358 | // x[i*2+1] = ... (1) | ||||
| 359 | // x[i*2+4] = ... (2) | ||||
| 360 | // x[i*2+5] = ... (2) | ||||
| 361 | // x[(i+1234)*2+5678] = ... (3) | ||||
| 362 | // x[(i+1234)*2+5679] = ... (3) | ||||
| 363 | // | ||||
| 364 | // The loop will be rerolled by adding a new loop induction variable, | ||||
| 365 | // one for the Base instruction in each DAGRootSet. | ||||
| 366 | // | ||||
| 367 | struct DAGRootSet { | ||||
| 368 | Instruction *BaseInst; | ||||
| 369 | SmallInstructionVector Roots; | ||||
| 370 | |||||
| 371 | // The instructions between IV and BaseInst (but not including BaseInst). | ||||
| 372 | SmallInstructionSet SubsumedInsts; | ||||
| 373 | }; | ||||
| 374 | |||||
| 375 | // The set of all DAG roots, and state tracking of all roots | ||||
| 376 | // for a particular induction variable. | ||||
| 377 | struct DAGRootTracker { | ||||
| 378 | DAGRootTracker(LoopReroll *Parent, Loop *L, Instruction *IV, | ||||
| 379 | ScalarEvolution *SE, AliasAnalysis *AA, | ||||
| 380 | TargetLibraryInfo *TLI, DominatorTree *DT, LoopInfo *LI, | ||||
| 381 | bool PreserveLCSSA, | ||||
| 382 | DenseMap<Instruction *, int64_t> &IncrMap, | ||||
| 383 | Instruction *LoopCtrlIV) | ||||
| 384 | : Parent(Parent), L(L), SE(SE), AA(AA), TLI(TLI), DT(DT), LI(LI), | ||||
| 385 | PreserveLCSSA(PreserveLCSSA), IV(IV), IVToIncMap(IncrMap), | ||||
| 386 | LoopControlIV(LoopCtrlIV) {} | ||||
| 387 | |||||
| 388 | /// Stage 1: Find all the DAG roots for the induction variable. | ||||
| 389 | bool findRoots(); | ||||
| 390 | |||||
| 391 | /// Stage 2: Validate if the found roots are valid. | ||||
| 392 | bool validate(ReductionTracker &Reductions); | ||||
| 393 | |||||
| 394 | /// Stage 3: Assuming validate() returned true, perform the | ||||
| 395 | /// replacement. | ||||
| 396 | /// @param BackedgeTakenCount The backedge-taken count of L. | ||||
| 397 | void replace(const SCEV *BackedgeTakenCount); | ||||
| 398 | |||||
| 399 | protected: | ||||
| 400 | using UsesTy = MapVector<Instruction *, BitVector>; | ||||
| 401 | |||||
| 402 | void findRootsRecursive(Instruction *IVU, | ||||
| 403 | SmallInstructionSet SubsumedInsts); | ||||
| 404 | bool findRootsBase(Instruction *IVU, SmallInstructionSet SubsumedInsts); | ||||
| 405 | bool collectPossibleRoots(Instruction *Base, | ||||
| 406 | std::map<int64_t,Instruction*> &Roots); | ||||
| 407 | bool validateRootSet(DAGRootSet &DRS); | ||||
| 408 | |||||
| 409 | bool collectUsedInstructions(SmallInstructionSet &PossibleRedSet); | ||||
| 410 | void collectInLoopUserSet(const SmallInstructionVector &Roots, | ||||
| 411 | const SmallInstructionSet &Exclude, | ||||
| 412 | const SmallInstructionSet &Final, | ||||
| 413 | DenseSet<Instruction *> &Users); | ||||
| 414 | void collectInLoopUserSet(Instruction *Root, | ||||
| 415 | const SmallInstructionSet &Exclude, | ||||
| 416 | const SmallInstructionSet &Final, | ||||
| 417 | DenseSet<Instruction *> &Users); | ||||
| 418 | |||||
| 419 | UsesTy::iterator nextInstr(int Val, UsesTy &In, | ||||
| 420 | const SmallInstructionSet &Exclude, | ||||
| 421 | UsesTy::iterator *StartI=nullptr); | ||||
| 422 | bool isBaseInst(Instruction *I); | ||||
| 423 | bool isRootInst(Instruction *I); | ||||
| 424 | bool instrDependsOn(Instruction *I, | ||||
| 425 | UsesTy::iterator Start, | ||||
| 426 | UsesTy::iterator End); | ||||
| 427 | void replaceIV(DAGRootSet &DRS, const SCEV *Start, const SCEV *IncrExpr); | ||||
| 428 | |||||
| 429 | LoopReroll *Parent; | ||||
| 430 | |||||
| 431 | // Members of Parent, replicated here for brevity. | ||||
| 432 | Loop *L; | ||||
| 433 | ScalarEvolution *SE; | ||||
| 434 | AliasAnalysis *AA; | ||||
| 435 | TargetLibraryInfo *TLI; | ||||
| 436 | DominatorTree *DT; | ||||
| 437 | LoopInfo *LI; | ||||
| 438 | bool PreserveLCSSA; | ||||
| 439 | |||||
| 440 | // The loop induction variable. | ||||
| 441 | Instruction *IV; | ||||
| 442 | |||||
| 443 | // Loop step amount. | ||||
| 444 | int64_t Inc; | ||||
| 445 | |||||
| 446 | // Loop reroll count; if Inc == 1, this records the scaling applied | ||||
| 447 | // to the indvar: a[i*2+0] = ...; a[i*2+1] = ... ; | ||||
| 448 | // If Inc is not 1, Scale = Inc. | ||||
| 449 | uint64_t Scale; | ||||
| 450 | |||||
| 451 | // The roots themselves. | ||||
| 452 | SmallVector<DAGRootSet,16> RootSets; | ||||
| 453 | |||||
| 454 | // All increment instructions for IV. | ||||
| 455 | SmallInstructionVector LoopIncs; | ||||
| 456 | |||||
| 457 | // Map of all instructions in the loop (in order) to the iterations | ||||
| 458 | // they are used in (or specially, IL_All for instructions | ||||
| 459 | // used in the loop increment mechanism). | ||||
| 460 | UsesTy Uses; | ||||
| 461 | |||||
| 462 | // Map between induction variable and its increment | ||||
| 463 | DenseMap<Instruction *, int64_t> &IVToIncMap; | ||||
| 464 | |||||
| 465 | Instruction *LoopControlIV; | ||||
| 466 | }; | ||||
| 467 | |||||
| 468 | // Check if it is a compare-like instruction whose user is a branch | ||||
| 469 | bool isCompareUsedByBranch(Instruction *I) { | ||||
| 470 | auto *TI = I->getParent()->getTerminator(); | ||||
| |||||
| 471 | if (!isa<BranchInst>(TI) || !isa<CmpInst>(I)) | ||||
| 472 | return false; | ||||
| 473 | return I->hasOneUse() && TI->getOperand(0) == I; | ||||
| 474 | }; | ||||
| 475 | |||||
| 476 | bool isLoopControlIV(Loop *L, Instruction *IV); | ||||
| 477 | void collectPossibleIVs(Loop *L, SmallInstructionVector &PossibleIVs); | ||||
| 478 | void collectPossibleReductions(Loop *L, | ||||
| 479 | ReductionTracker &Reductions); | ||||
| 480 | bool reroll(Instruction *IV, Loop *L, BasicBlock *Header, | ||||
| 481 | const SCEV *BackedgeTakenCount, ReductionTracker &Reductions); | ||||
| 482 | }; | ||||
| 483 | |||||
| 484 | } // end anonymous namespace | ||||
| 485 | |||||
| 486 | char LoopReroll::ID = 0; | ||||
| 487 | |||||
| 488 | INITIALIZE_PASS_BEGIN(LoopReroll, "loop-reroll", "Reroll loops", false, false)static void *initializeLoopRerollPassOnce(PassRegistry &Registry ) { | ||||
| 489 | INITIALIZE_PASS_DEPENDENCY(LoopPass)initializeLoopPassPass(Registry); | ||||
| 490 | INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)initializeTargetLibraryInfoWrapperPassPass(Registry); | ||||
| 491 | INITIALIZE_PASS_END(LoopReroll, "loop-reroll", "Reroll loops", false, false)PassInfo *PI = new PassInfo( "Reroll loops", "loop-reroll", & LoopReroll::ID, PassInfo::NormalCtor_t(callDefaultCtor<LoopReroll >), false, false); Registry.registerPass(*PI, true); return PI; } static llvm::once_flag InitializeLoopRerollPassFlag; void llvm::initializeLoopRerollPass(PassRegistry &Registry) { llvm::call_once(InitializeLoopRerollPassFlag, initializeLoopRerollPassOnce , std::ref(Registry)); } | ||||
| 492 | |||||
| 493 | Pass *llvm::createLoopRerollPass() { | ||||
| 494 | return new LoopReroll; | ||||
| 495 | } | ||||
| 496 | |||||
| 497 | // Returns true if the provided instruction is used outside the given loop. | ||||
| 498 | // This operates like Instruction::isUsedOutsideOfBlock, but considers PHIs in | ||||
| 499 | // non-loop blocks to be outside the loop. | ||||
| 500 | static bool hasUsesOutsideLoop(Instruction *I, Loop *L) { | ||||
| 501 | for (User *U : I->users()) { | ||||
| 502 | if (!L->contains(cast<Instruction>(U))) | ||||
| 503 | return true; | ||||
| 504 | } | ||||
| 505 | return false; | ||||
| 506 | } | ||||
| 507 | |||||
| 508 | // Check if an IV is only used to control the loop. There are two cases: | ||||
| 509 | // 1. It only has one use which is loop increment, and the increment is only | ||||
| 510 | // used by comparison and the PHI (could has sext with nsw in between), and the | ||||
| 511 | // comparison is only used by branch. | ||||
| 512 | // 2. It is used by loop increment and the comparison, the loop increment is | ||||
| 513 | // only used by the PHI, and the comparison is used only by the branch. | ||||
| 514 | bool LoopReroll::isLoopControlIV(Loop *L, Instruction *IV) { | ||||
| 515 | unsigned IVUses = IV->getNumUses(); | ||||
| 516 | if (IVUses != 2 && IVUses != 1) | ||||
| 517 | return false; | ||||
| 518 | |||||
| 519 | for (auto *User : IV->users()) { | ||||
| 520 | int32_t IncOrCmpUses = User->getNumUses(); | ||||
| 521 | bool IsCompInst = isCompareUsedByBranch(cast<Instruction>(User)); | ||||
| 522 | |||||
| 523 | // User can only have one or two uses. | ||||
| 524 | if (IncOrCmpUses != 2 && IncOrCmpUses != 1) | ||||
| 525 | return false; | ||||
| 526 | |||||
| 527 | // Case 1 | ||||
| 528 | if (IVUses
| ||||
| 529 | // The only user must be the loop increment. | ||||
| 530 | // The loop increment must have two uses. | ||||
| 531 | if (IsCompInst || IncOrCmpUses != 2) | ||||
| 532 | return false; | ||||
| 533 | } | ||||
| 534 | |||||
| 535 | // Case 2 | ||||
| 536 | if (IVUses
| ||||
| 537 | return false; | ||||
| 538 | |||||
| 539 | // The users of the IV must be a binary operation or a comparison | ||||
| 540 | if (auto *BO
| ||||
| 541 | if (BO->getOpcode() == Instruction::Add) { | ||||
| 542 | // Loop Increment | ||||
| 543 | // User of Loop Increment should be either PHI or CMP | ||||
| 544 | for (auto *UU : User->users()) { | ||||
| 545 | if (PHINode *PN
| ||||
| 546 | if (PN != IV) | ||||
| 547 | return false; | ||||
| 548 | } | ||||
| 549 | // Must be a CMP or an ext (of a value with nsw) then CMP | ||||
| 550 | else { | ||||
| 551 | Instruction *UUser = dyn_cast<Instruction>(UU); | ||||
| 552 | // Skip SExt if we are extending an nsw value | ||||
| 553 | // TODO: Allow ZExt too | ||||
| 554 | if (BO->hasNoSignedWrap() && UUser && UUser->hasOneUse() && | ||||
| 555 | isa<SExtInst>(UUser)) | ||||
| 556 | UUser = dyn_cast<Instruction>(*(UUser->user_begin())); | ||||
| 557 | if (!isCompareUsedByBranch(UUser)) | ||||
| 558 | return false; | ||||
| 559 | } | ||||
| 560 | } | ||||
| 561 | } else | ||||
| 562 | return false; | ||||
| 563 | // Compare : can only have one use, and must be branch | ||||
| 564 | } else if (!IsCompInst) | ||||
| 565 | return false; | ||||
| 566 | } | ||||
| 567 | return true; | ||||
| 568 | } | ||||
| 569 | |||||
| 570 | // Collect the list of loop induction variables with respect to which it might | ||||
| 571 | // be possible to reroll the loop. | ||||
| 572 | void LoopReroll::collectPossibleIVs(Loop *L, | ||||
| 573 | SmallInstructionVector &PossibleIVs) { | ||||
| 574 | BasicBlock *Header = L->getHeader(); | ||||
| 575 | for (BasicBlock::iterator I = Header->begin(), | ||||
| 576 | IE = Header->getFirstInsertionPt(); I != IE; ++I) { | ||||
| 577 | if (!isa<PHINode>(I)) | ||||
| 578 | continue; | ||||
| 579 | if (!I->getType()->isIntegerTy() && !I->getType()->isPointerTy()) | ||||
| 580 | continue; | ||||
| 581 | |||||
| 582 | if (const SCEVAddRecExpr *PHISCEV
| ||||
| 583 | dyn_cast<SCEVAddRecExpr>(SE->getSCEV(&*I))) { | ||||
| 584 | if (PHISCEV->getLoop() != L) | ||||
| 585 | continue; | ||||
| 586 | if (!PHISCEV->isAffine()) | ||||
| 587 | continue; | ||||
| 588 | auto IncSCEV = dyn_cast<SCEVConstant>(PHISCEV->getStepRecurrence(*SE)); | ||||
| 589 | if (IncSCEV
| ||||
| 590 | IVToIncMap[&*I] = IncSCEV->getValue()->getSExtValue(); | ||||
| 591 | LLVM_DEBUG(dbgs() << "LRR: Possible IV: " << *I << " = " << *PHISCEVdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: Possible IV: " << *I << " = " << *PHISCEV << "\n"; } } while (false) | ||||
| 592 | << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: Possible IV: " << *I << " = " << *PHISCEV << "\n"; } } while (false); | ||||
| 593 | |||||
| 594 | if (isLoopControlIV(L, &*I)) { | ||||
| 595 | assert(!LoopControlIV && "Found two loop control only IV")((!LoopControlIV && "Found two loop control only IV") ? static_cast<void> (0) : __assert_fail ("!LoopControlIV && \"Found two loop control only IV\"" , "/build/llvm-toolchain-snapshot-10~svn374814/lib/Transforms/Scalar/LoopRerollPass.cpp" , 595, __PRETTY_FUNCTION__)); | ||||
| 596 | LoopControlIV = &(*I); | ||||
| 597 | LLVM_DEBUG(dbgs() << "LRR: Possible loop control only IV: " << *Ido { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: Possible loop control only IV: " << *I << " = " << *PHISCEV << "\n"; } } while (false) | ||||
| 598 | << " = " << *PHISCEV << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: Possible loop control only IV: " << *I << " = " << *PHISCEV << "\n"; } } while (false); | ||||
| 599 | } else | ||||
| 600 | PossibleIVs.push_back(&*I); | ||||
| 601 | } | ||||
| 602 | } | ||||
| 603 | } | ||||
| 604 | } | ||||
| 605 | |||||
| 606 | // Add the remainder of the reduction-variable chain to the instruction vector | ||||
| 607 | // (the initial PHINode has already been added). If successful, the object is | ||||
| 608 | // marked as valid. | ||||
| 609 | void LoopReroll::SimpleLoopReduction::add(Loop *L) { | ||||
| 610 | assert(!Valid && "Cannot add to an already-valid chain")((!Valid && "Cannot add to an already-valid chain") ? static_cast<void> (0) : __assert_fail ("!Valid && \"Cannot add to an already-valid chain\"" , "/build/llvm-toolchain-snapshot-10~svn374814/lib/Transforms/Scalar/LoopRerollPass.cpp" , 610, __PRETTY_FUNCTION__)); | ||||
| 611 | |||||
| 612 | // The reduction variable must be a chain of single-use instructions | ||||
| 613 | // (including the PHI), except for the last value (which is used by the PHI | ||||
| 614 | // and also outside the loop). | ||||
| 615 | Instruction *C = Instructions.front(); | ||||
| 616 | if (C->user_empty()) | ||||
| 617 | return; | ||||
| 618 | |||||
| 619 | do { | ||||
| 620 | C = cast<Instruction>(*C->user_begin()); | ||||
| 621 | if (C->hasOneUse()) { | ||||
| 622 | if (!C->isBinaryOp()) | ||||
| 623 | return; | ||||
| 624 | |||||
| 625 | if (!(isa<PHINode>(Instructions.back()) || | ||||
| 626 | C->isSameOperationAs(Instructions.back()))) | ||||
| 627 | return; | ||||
| 628 | |||||
| 629 | Instructions.push_back(C); | ||||
| 630 | } | ||||
| 631 | } while (C->hasOneUse()); | ||||
| 632 | |||||
| 633 | if (Instructions.size() < 2 || | ||||
| 634 | !C->isSameOperationAs(Instructions.back()) || | ||||
| 635 | C->use_empty()) | ||||
| 636 | return; | ||||
| 637 | |||||
| 638 | // C is now the (potential) last instruction in the reduction chain. | ||||
| 639 | for (User *U : C->users()) { | ||||
| 640 | // The only in-loop user can be the initial PHI. | ||||
| 641 | if (L->contains(cast<Instruction>(U))) | ||||
| 642 | if (cast<Instruction>(U) != Instructions.front()) | ||||
| 643 | return; | ||||
| 644 | } | ||||
| 645 | |||||
| 646 | Instructions.push_back(C); | ||||
| 647 | Valid = true; | ||||
| 648 | } | ||||
| 649 | |||||
| 650 | // Collect the vector of possible reduction variables. | ||||
| 651 | void LoopReroll::collectPossibleReductions(Loop *L, | ||||
| 652 | ReductionTracker &Reductions) { | ||||
| 653 | BasicBlock *Header = L->getHeader(); | ||||
| 654 | for (BasicBlock::iterator I = Header->begin(), | ||||
| 655 | IE = Header->getFirstInsertionPt(); I != IE; ++I) { | ||||
| 656 | if (!isa<PHINode>(I)) | ||||
| 657 | continue; | ||||
| 658 | if (!I->getType()->isSingleValueType()) | ||||
| 659 | continue; | ||||
| 660 | |||||
| 661 | SimpleLoopReduction SLR(&*I, L); | ||||
| 662 | if (!SLR.valid()) | ||||
| 663 | continue; | ||||
| 664 | |||||
| 665 | LLVM_DEBUG(dbgs() << "LRR: Possible reduction: " << *I << " (with "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: Possible reduction: " << *I << " (with " << SLR.size() << " chained instructions)\n" ; } } while (false) | ||||
| 666 | << SLR.size() << " chained instructions)\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: Possible reduction: " << *I << " (with " << SLR.size() << " chained instructions)\n" ; } } while (false); | ||||
| 667 | Reductions.addSLR(SLR); | ||||
| 668 | } | ||||
| 669 | } | ||||
| 670 | |||||
| 671 | // Collect the set of all users of the provided root instruction. This set of | ||||
| 672 | // users contains not only the direct users of the root instruction, but also | ||||
| 673 | // all users of those users, and so on. There are two exceptions: | ||||
| 674 | // | ||||
| 675 | // 1. Instructions in the set of excluded instructions are never added to the | ||||
| 676 | // use set (even if they are users). This is used, for example, to exclude | ||||
| 677 | // including root increments in the use set of the primary IV. | ||||
| 678 | // | ||||
| 679 | // 2. Instructions in the set of final instructions are added to the use set | ||||
| 680 | // if they are users, but their users are not added. This is used, for | ||||
| 681 | // example, to prevent a reduction update from forcing all later reduction | ||||
| 682 | // updates into the use set. | ||||
| 683 | void LoopReroll::DAGRootTracker::collectInLoopUserSet( | ||||
| 684 | Instruction *Root, const SmallInstructionSet &Exclude, | ||||
| 685 | const SmallInstructionSet &Final, | ||||
| 686 | DenseSet<Instruction *> &Users) { | ||||
| 687 | SmallInstructionVector Queue(1, Root); | ||||
| 688 | while (!Queue.empty()) { | ||||
| 689 | Instruction *I = Queue.pop_back_val(); | ||||
| 690 | if (!Users.insert(I).second) | ||||
| 691 | continue; | ||||
| 692 | |||||
| 693 | if (!Final.count(I)) | ||||
| 694 | for (Use &U : I->uses()) { | ||||
| 695 | Instruction *User = cast<Instruction>(U.getUser()); | ||||
| 696 | if (PHINode *PN = dyn_cast<PHINode>(User)) { | ||||
| 697 | // Ignore "wrap-around" uses to PHIs of this loop's header. | ||||
| 698 | if (PN->getIncomingBlock(U) == L->getHeader()) | ||||
| 699 | continue; | ||||
| 700 | } | ||||
| 701 | |||||
| 702 | if (L->contains(User) && !Exclude.count(User)) { | ||||
| 703 | Queue.push_back(User); | ||||
| 704 | } | ||||
| 705 | } | ||||
| 706 | |||||
| 707 | // We also want to collect single-user "feeder" values. | ||||
| 708 | for (User::op_iterator OI = I->op_begin(), | ||||
| 709 | OIE = I->op_end(); OI != OIE; ++OI) { | ||||
| 710 | if (Instruction *Op = dyn_cast<Instruction>(*OI)) | ||||
| 711 | if (Op->hasOneUse() && L->contains(Op) && !Exclude.count(Op) && | ||||
| 712 | !Final.count(Op)) | ||||
| 713 | Queue.push_back(Op); | ||||
| 714 | } | ||||
| 715 | } | ||||
| 716 | } | ||||
| 717 | |||||
| 718 | // Collect all of the users of all of the provided root instructions (combined | ||||
| 719 | // into a single set). | ||||
| 720 | void LoopReroll::DAGRootTracker::collectInLoopUserSet( | ||||
| 721 | const SmallInstructionVector &Roots, | ||||
| 722 | const SmallInstructionSet &Exclude, | ||||
| 723 | const SmallInstructionSet &Final, | ||||
| 724 | DenseSet<Instruction *> &Users) { | ||||
| 725 | for (Instruction *Root : Roots) | ||||
| 726 | collectInLoopUserSet(Root, Exclude, Final, Users); | ||||
| 727 | } | ||||
| 728 | |||||
| 729 | static bool isUnorderedLoadStore(Instruction *I) { | ||||
| 730 | if (LoadInst *LI = dyn_cast<LoadInst>(I)) | ||||
| 731 | return LI->isUnordered(); | ||||
| 732 | if (StoreInst *SI = dyn_cast<StoreInst>(I)) | ||||
| 733 | return SI->isUnordered(); | ||||
| 734 | if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(I)) | ||||
| 735 | return !MI->isVolatile(); | ||||
| 736 | return false; | ||||
| 737 | } | ||||
| 738 | |||||
| 739 | /// Return true if IVU is a "simple" arithmetic operation. | ||||
| 740 | /// This is used for narrowing the search space for DAGRoots; only arithmetic | ||||
| 741 | /// and GEPs can be part of a DAGRoot. | ||||
| 742 | static bool isSimpleArithmeticOp(User *IVU) { | ||||
| 743 | if (Instruction *I = dyn_cast<Instruction>(IVU)) { | ||||
| 744 | switch (I->getOpcode()) { | ||||
| 745 | default: return false; | ||||
| 746 | case Instruction::Add: | ||||
| 747 | case Instruction::Sub: | ||||
| 748 | case Instruction::Mul: | ||||
| 749 | case Instruction::Shl: | ||||
| 750 | case Instruction::AShr: | ||||
| 751 | case Instruction::LShr: | ||||
| 752 | case Instruction::GetElementPtr: | ||||
| 753 | case Instruction::Trunc: | ||||
| 754 | case Instruction::ZExt: | ||||
| 755 | case Instruction::SExt: | ||||
| 756 | return true; | ||||
| 757 | } | ||||
| 758 | } | ||||
| 759 | return false; | ||||
| 760 | } | ||||
| 761 | |||||
| 762 | static bool isLoopIncrement(User *U, Instruction *IV) { | ||||
| 763 | BinaryOperator *BO = dyn_cast<BinaryOperator>(U); | ||||
| 764 | |||||
| 765 | if ((BO && BO->getOpcode() != Instruction::Add) || | ||||
| 766 | (!BO && !isa<GetElementPtrInst>(U))) | ||||
| 767 | return false; | ||||
| 768 | |||||
| 769 | for (auto *UU : U->users()) { | ||||
| 770 | PHINode *PN = dyn_cast<PHINode>(UU); | ||||
| 771 | if (PN && PN == IV) | ||||
| 772 | return true; | ||||
| 773 | } | ||||
| 774 | return false; | ||||
| 775 | } | ||||
| 776 | |||||
| 777 | bool LoopReroll::DAGRootTracker:: | ||||
| 778 | collectPossibleRoots(Instruction *Base, std::map<int64_t,Instruction*> &Roots) { | ||||
| 779 | SmallInstructionVector BaseUsers; | ||||
| 780 | |||||
| 781 | for (auto *I : Base->users()) { | ||||
| 782 | ConstantInt *CI = nullptr; | ||||
| 783 | |||||
| 784 | if (isLoopIncrement(I, IV)) { | ||||
| 785 | LoopIncs.push_back(cast<Instruction>(I)); | ||||
| 786 | continue; | ||||
| 787 | } | ||||
| 788 | |||||
| 789 | // The root nodes must be either GEPs, ORs or ADDs. | ||||
| 790 | if (auto *BO = dyn_cast<BinaryOperator>(I)) { | ||||
| 791 | if (BO->getOpcode() == Instruction::Add || | ||||
| 792 | BO->getOpcode() == Instruction::Or) | ||||
| 793 | CI = dyn_cast<ConstantInt>(BO->getOperand(1)); | ||||
| 794 | } else if (auto *GEP = dyn_cast<GetElementPtrInst>(I)) { | ||||
| 795 | Value *LastOperand = GEP->getOperand(GEP->getNumOperands()-1); | ||||
| 796 | CI = dyn_cast<ConstantInt>(LastOperand); | ||||
| 797 | } | ||||
| 798 | |||||
| 799 | if (!CI) { | ||||
| 800 | if (Instruction *II = dyn_cast<Instruction>(I)) { | ||||
| 801 | BaseUsers.push_back(II); | ||||
| 802 | continue; | ||||
| 803 | } else { | ||||
| 804 | LLVM_DEBUG(dbgs() << "LRR: Aborting due to non-instruction: " << *Ido { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: Aborting due to non-instruction: " << *I << "\n"; } } while (false) | ||||
| 805 | << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: Aborting due to non-instruction: " << *I << "\n"; } } while (false); | ||||
| 806 | return false; | ||||
| 807 | } | ||||
| 808 | } | ||||
| 809 | |||||
| 810 | int64_t V = std::abs(CI->getValue().getSExtValue()); | ||||
| 811 | if (Roots.find(V) != Roots.end()) | ||||
| 812 | // No duplicates, please. | ||||
| 813 | return false; | ||||
| 814 | |||||
| 815 | Roots[V] = cast<Instruction>(I); | ||||
| 816 | } | ||||
| 817 | |||||
| 818 | // Make sure we have at least two roots. | ||||
| 819 | if (Roots.empty() || (Roots.size() == 1 && BaseUsers.empty())) | ||||
| 820 | return false; | ||||
| 821 | |||||
| 822 | // If we found non-loop-inc, non-root users of Base, assume they are | ||||
| 823 | // for the zeroth root index. This is because "add %a, 0" gets optimized | ||||
| 824 | // away. | ||||
| 825 | if (BaseUsers.size()) { | ||||
| 826 | if (Roots.find(0) != Roots.end()) { | ||||
| 827 | LLVM_DEBUG(dbgs() << "LRR: Multiple roots found for base - aborting!\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: Multiple roots found for base - aborting!\n" ; } } while (false); | ||||
| 828 | return false; | ||||
| 829 | } | ||||
| 830 | Roots[0] = Base; | ||||
| 831 | } | ||||
| 832 | |||||
| 833 | // Calculate the number of users of the base, or lowest indexed, iteration. | ||||
| 834 | unsigned NumBaseUses = BaseUsers.size(); | ||||
| 835 | if (NumBaseUses == 0) | ||||
| 836 | NumBaseUses = Roots.begin()->second->getNumUses(); | ||||
| 837 | |||||
| 838 | // Check that every node has the same number of users. | ||||
| 839 | for (auto &KV : Roots) { | ||||
| 840 | if (KV.first == 0) | ||||
| 841 | continue; | ||||
| 842 | if (!KV.second->hasNUses(NumBaseUses)) { | ||||
| 843 | LLVM_DEBUG(dbgs() << "LRR: Aborting - Root and Base #users not the same: "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: Aborting - Root and Base #users not the same: " << "#Base=" << NumBaseUses << ", #Root=" << KV.second->getNumUses() << "\n"; } } while (false) | ||||
| 844 | << "#Base=" << NumBaseUsesdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: Aborting - Root and Base #users not the same: " << "#Base=" << NumBaseUses << ", #Root=" << KV.second->getNumUses() << "\n"; } } while (false) | ||||
| 845 | << ", #Root=" << KV.second->getNumUses() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: Aborting - Root and Base #users not the same: " << "#Base=" << NumBaseUses << ", #Root=" << KV.second->getNumUses() << "\n"; } } while (false); | ||||
| 846 | return false; | ||||
| 847 | } | ||||
| 848 | } | ||||
| 849 | |||||
| 850 | return true; | ||||
| 851 | } | ||||
| 852 | |||||
| 853 | void LoopReroll::DAGRootTracker:: | ||||
| 854 | findRootsRecursive(Instruction *I, SmallInstructionSet SubsumedInsts) { | ||||
| 855 | // Does the user look like it could be part of a root set? | ||||
| 856 | // All its users must be simple arithmetic ops. | ||||
| 857 | if (I->hasNUsesOrMore(IL_MaxRerollIterations + 1)) | ||||
| 858 | return; | ||||
| 859 | |||||
| 860 | if (I != IV && findRootsBase(I, SubsumedInsts)) | ||||
| 861 | return; | ||||
| 862 | |||||
| 863 | SubsumedInsts.insert(I); | ||||
| 864 | |||||
| 865 | for (User *V : I->users()) { | ||||
| 866 | Instruction *I = cast<Instruction>(V); | ||||
| 867 | if (is_contained(LoopIncs, I)) | ||||
| 868 | continue; | ||||
| 869 | |||||
| 870 | if (!isSimpleArithmeticOp(I)) | ||||
| 871 | continue; | ||||
| 872 | |||||
| 873 | // The recursive call makes a copy of SubsumedInsts. | ||||
| 874 | findRootsRecursive(I, SubsumedInsts); | ||||
| 875 | } | ||||
| 876 | } | ||||
| 877 | |||||
| 878 | bool LoopReroll::DAGRootTracker::validateRootSet(DAGRootSet &DRS) { | ||||
| 879 | if (DRS.Roots.empty()) | ||||
| 880 | return false; | ||||
| 881 | |||||
| 882 | // Consider a DAGRootSet with N-1 roots (so N different values including | ||||
| 883 | // BaseInst). | ||||
| 884 | // Define d = Roots[0] - BaseInst, which should be the same as | ||||
| 885 | // Roots[I] - Roots[I-1] for all I in [1..N). | ||||
| 886 | // Define D = BaseInst@J - BaseInst@J-1, where "@J" means the value at the | ||||
| 887 | // loop iteration J. | ||||
| 888 | // | ||||
| 889 | // Now, For the loop iterations to be consecutive: | ||||
| 890 | // D = d * N | ||||
| 891 | const auto *ADR = dyn_cast<SCEVAddRecExpr>(SE->getSCEV(DRS.BaseInst)); | ||||
| 892 | if (!ADR) | ||||
| 893 | return false; | ||||
| 894 | |||||
| 895 | // Check that the first root is evenly spaced. | ||||
| 896 | unsigned N = DRS.Roots.size() + 1; | ||||
| 897 | const SCEV *StepSCEV = SE->getMinusSCEV(SE->getSCEV(DRS.Roots[0]), ADR); | ||||
| 898 | const SCEV *ScaleSCEV = SE->getConstant(StepSCEV->getType(), N); | ||||
| 899 | if (ADR->getStepRecurrence(*SE) != SE->getMulExpr(StepSCEV, ScaleSCEV)) | ||||
| 900 | return false; | ||||
| 901 | |||||
| 902 | // Check that the remainling roots are evenly spaced. | ||||
| 903 | for (unsigned i = 1; i < N - 1; ++i) { | ||||
| 904 | const SCEV *NewStepSCEV = SE->getMinusSCEV(SE->getSCEV(DRS.Roots[i]), | ||||
| 905 | SE->getSCEV(DRS.Roots[i-1])); | ||||
| 906 | if (NewStepSCEV != StepSCEV) | ||||
| 907 | return false; | ||||
| 908 | } | ||||
| 909 | |||||
| 910 | return true; | ||||
| 911 | } | ||||
| 912 | |||||
| 913 | bool LoopReroll::DAGRootTracker:: | ||||
| 914 | findRootsBase(Instruction *IVU, SmallInstructionSet SubsumedInsts) { | ||||
| 915 | // The base of a RootSet must be an AddRec, so it can be erased. | ||||
| 916 | const auto *IVU_ADR = dyn_cast<SCEVAddRecExpr>(SE->getSCEV(IVU)); | ||||
| 917 | if (!IVU_ADR || IVU_ADR->getLoop() != L) | ||||
| 918 | return false; | ||||
| 919 | |||||
| 920 | std::map<int64_t, Instruction*> V; | ||||
| 921 | if (!collectPossibleRoots(IVU, V)) | ||||
| 922 | return false; | ||||
| 923 | |||||
| 924 | // If we didn't get a root for index zero, then IVU must be | ||||
| 925 | // subsumed. | ||||
| 926 | if (V.find(0) == V.end()) | ||||
| 927 | SubsumedInsts.insert(IVU); | ||||
| 928 | |||||
| 929 | // Partition the vector into monotonically increasing indexes. | ||||
| 930 | DAGRootSet DRS; | ||||
| 931 | DRS.BaseInst = nullptr; | ||||
| 932 | |||||
| 933 | SmallVector<DAGRootSet, 16> PotentialRootSets; | ||||
| 934 | |||||
| 935 | for (auto &KV : V) { | ||||
| 936 | if (!DRS.BaseInst) { | ||||
| 937 | DRS.BaseInst = KV.second; | ||||
| 938 | DRS.SubsumedInsts = SubsumedInsts; | ||||
| 939 | } else if (DRS.Roots.empty()) { | ||||
| 940 | DRS.Roots.push_back(KV.second); | ||||
| 941 | } else if (V.find(KV.first - 1) != V.end()) { | ||||
| 942 | DRS.Roots.push_back(KV.second); | ||||
| 943 | } else { | ||||
| 944 | // Linear sequence terminated. | ||||
| 945 | if (!validateRootSet(DRS)) | ||||
| 946 | return false; | ||||
| 947 | |||||
| 948 | // Construct a new DAGRootSet with the next sequence. | ||||
| 949 | PotentialRootSets.push_back(DRS); | ||||
| 950 | DRS.BaseInst = KV.second; | ||||
| 951 | DRS.Roots.clear(); | ||||
| 952 | } | ||||
| 953 | } | ||||
| 954 | |||||
| 955 | if (!validateRootSet(DRS)) | ||||
| 956 | return false; | ||||
| 957 | |||||
| 958 | PotentialRootSets.push_back(DRS); | ||||
| 959 | |||||
| 960 | RootSets.append(PotentialRootSets.begin(), PotentialRootSets.end()); | ||||
| 961 | |||||
| 962 | return true; | ||||
| 963 | } | ||||
| 964 | |||||
| 965 | bool LoopReroll::DAGRootTracker::findRoots() { | ||||
| 966 | Inc = IVToIncMap[IV]; | ||||
| 967 | |||||
| 968 | assert(RootSets.empty() && "Unclean state!")((RootSets.empty() && "Unclean state!") ? static_cast <void> (0) : __assert_fail ("RootSets.empty() && \"Unclean state!\"" , "/build/llvm-toolchain-snapshot-10~svn374814/lib/Transforms/Scalar/LoopRerollPass.cpp" , 968, __PRETTY_FUNCTION__)); | ||||
| 969 | if (std::abs(Inc) == 1) { | ||||
| 970 | for (auto *IVU : IV->users()) { | ||||
| 971 | if (isLoopIncrement(IVU, IV)) | ||||
| 972 | LoopIncs.push_back(cast<Instruction>(IVU)); | ||||
| 973 | } | ||||
| 974 | findRootsRecursive(IV, SmallInstructionSet()); | ||||
| 975 | LoopIncs.push_back(IV); | ||||
| 976 | } else { | ||||
| 977 | if (!findRootsBase(IV, SmallInstructionSet())) | ||||
| 978 | return false; | ||||
| 979 | } | ||||
| 980 | |||||
| 981 | // Ensure all sets have the same size. | ||||
| 982 | if (RootSets.empty()) { | ||||
| 983 | LLVM_DEBUG(dbgs() << "LRR: Aborting because no root sets found!\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: Aborting because no root sets found!\n" ; } } while (false); | ||||
| 984 | return false; | ||||
| 985 | } | ||||
| 986 | for (auto &V : RootSets) { | ||||
| 987 | if (V.Roots.empty() || V.Roots.size() != RootSets[0].Roots.size()) { | ||||
| 988 | LLVM_DEBUG(do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: Aborting because not all root sets have the same size\n" ; } } while (false) | ||||
| 989 | dbgs()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: Aborting because not all root sets have the same size\n" ; } } while (false) | ||||
| 990 | << "LRR: Aborting because not all root sets have the same size\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: Aborting because not all root sets have the same size\n" ; } } while (false); | ||||
| 991 | return false; | ||||
| 992 | } | ||||
| 993 | } | ||||
| 994 | |||||
| 995 | Scale = RootSets[0].Roots.size() + 1; | ||||
| 996 | |||||
| 997 | if (Scale > IL_MaxRerollIterations) { | ||||
| 998 | LLVM_DEBUG(dbgs() << "LRR: Aborting - too many iterations found. "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: Aborting - too many iterations found. " << "#Found=" << Scale << ", #Max=" << IL_MaxRerollIterations << "\n"; } } while (false) | ||||
| 999 | << "#Found=" << Scaledo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: Aborting - too many iterations found. " << "#Found=" << Scale << ", #Max=" << IL_MaxRerollIterations << "\n"; } } while (false) | ||||
| 1000 | << ", #Max=" << IL_MaxRerollIterations << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: Aborting - too many iterations found. " << "#Found=" << Scale << ", #Max=" << IL_MaxRerollIterations << "\n"; } } while (false); | ||||
| 1001 | return false; | ||||
| 1002 | } | ||||
| 1003 | |||||
| 1004 | LLVM_DEBUG(dbgs() << "LRR: Successfully found roots: Scale=" << Scaledo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: Successfully found roots: Scale=" << Scale << "\n"; } } while (false) | ||||
| 1005 | << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: Successfully found roots: Scale=" << Scale << "\n"; } } while (false); | ||||
| 1006 | |||||
| 1007 | return true; | ||||
| 1008 | } | ||||
| 1009 | |||||
| 1010 | bool LoopReroll::DAGRootTracker::collectUsedInstructions(SmallInstructionSet &PossibleRedSet) { | ||||
| 1011 | // Populate the MapVector with all instructions in the block, in order first, | ||||
| 1012 | // so we can iterate over the contents later in perfect order. | ||||
| 1013 | for (auto &I : *L->getHeader()) { | ||||
| 1014 | Uses[&I].resize(IL_End); | ||||
| 1015 | } | ||||
| 1016 | |||||
| 1017 | SmallInstructionSet Exclude; | ||||
| 1018 | for (auto &DRS : RootSets) { | ||||
| 1019 | Exclude.insert(DRS.Roots.begin(), DRS.Roots.end()); | ||||
| 1020 | Exclude.insert(DRS.SubsumedInsts.begin(), DRS.SubsumedInsts.end()); | ||||
| 1021 | Exclude.insert(DRS.BaseInst); | ||||
| 1022 | } | ||||
| 1023 | Exclude.insert(LoopIncs.begin(), LoopIncs.end()); | ||||
| 1024 | |||||
| 1025 | for (auto &DRS : RootSets) { | ||||
| 1026 | DenseSet<Instruction*> VBase; | ||||
| 1027 | collectInLoopUserSet(DRS.BaseInst, Exclude, PossibleRedSet, VBase); | ||||
| 1028 | for (auto *I : VBase) { | ||||
| 1029 | Uses[I].set(0); | ||||
| 1030 | } | ||||
| 1031 | |||||
| 1032 | unsigned Idx = 1; | ||||
| 1033 | for (auto *Root : DRS.Roots) { | ||||
| 1034 | DenseSet<Instruction*> V; | ||||
| 1035 | collectInLoopUserSet(Root, Exclude, PossibleRedSet, V); | ||||
| 1036 | |||||
| 1037 | // While we're here, check the use sets are the same size. | ||||
| 1038 | if (V.size() != VBase.size()) { | ||||
| 1039 | LLVM_DEBUG(dbgs() << "LRR: Aborting - use sets are different sizes\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: Aborting - use sets are different sizes\n" ; } } while (false); | ||||
| 1040 | return false; | ||||
| 1041 | } | ||||
| 1042 | |||||
| 1043 | for (auto *I : V) { | ||||
| 1044 | Uses[I].set(Idx); | ||||
| 1045 | } | ||||
| 1046 | ++Idx; | ||||
| 1047 | } | ||||
| 1048 | |||||
| 1049 | // Make sure our subsumed instructions are remembered too. | ||||
| 1050 | for (auto *I : DRS.SubsumedInsts) { | ||||
| 1051 | Uses[I].set(IL_All); | ||||
| 1052 | } | ||||
| 1053 | } | ||||
| 1054 | |||||
| 1055 | // Make sure the loop increments are also accounted for. | ||||
| 1056 | |||||
| 1057 | Exclude.clear(); | ||||
| 1058 | for (auto &DRS : RootSets) { | ||||
| 1059 | Exclude.insert(DRS.Roots.begin(), DRS.Roots.end()); | ||||
| 1060 | Exclude.insert(DRS.SubsumedInsts.begin(), DRS.SubsumedInsts.end()); | ||||
| 1061 | Exclude.insert(DRS.BaseInst); | ||||
| 1062 | } | ||||
| 1063 | |||||
| 1064 | DenseSet<Instruction*> V; | ||||
| 1065 | collectInLoopUserSet(LoopIncs, Exclude, PossibleRedSet, V); | ||||
| 1066 | for (auto *I : V) { | ||||
| 1067 | Uses[I].set(IL_All); | ||||
| 1068 | } | ||||
| 1069 | |||||
| 1070 | return true; | ||||
| 1071 | } | ||||
| 1072 | |||||
| 1073 | /// Get the next instruction in "In" that is a member of set Val. | ||||
| 1074 | /// Start searching from StartI, and do not return anything in Exclude. | ||||
| 1075 | /// If StartI is not given, start from In.begin(). | ||||
| 1076 | LoopReroll::DAGRootTracker::UsesTy::iterator | ||||
| 1077 | LoopReroll::DAGRootTracker::nextInstr(int Val, UsesTy &In, | ||||
| 1078 | const SmallInstructionSet &Exclude, | ||||
| 1079 | UsesTy::iterator *StartI) { | ||||
| 1080 | UsesTy::iterator I = StartI ? *StartI : In.begin(); | ||||
| 1081 | while (I != In.end() && (I->second.test(Val) == 0 || | ||||
| 1082 | Exclude.count(I->first) != 0)) | ||||
| 1083 | ++I; | ||||
| 1084 | return I; | ||||
| 1085 | } | ||||
| 1086 | |||||
| 1087 | bool LoopReroll::DAGRootTracker::isBaseInst(Instruction *I) { | ||||
| 1088 | for (auto &DRS : RootSets) { | ||||
| 1089 | if (DRS.BaseInst == I) | ||||
| 1090 | return true; | ||||
| 1091 | } | ||||
| 1092 | return false; | ||||
| 1093 | } | ||||
| 1094 | |||||
| 1095 | bool LoopReroll::DAGRootTracker::isRootInst(Instruction *I) { | ||||
| 1096 | for (auto &DRS : RootSets) { | ||||
| 1097 | if (is_contained(DRS.Roots, I)) | ||||
| 1098 | return true; | ||||
| 1099 | } | ||||
| 1100 | return false; | ||||
| 1101 | } | ||||
| 1102 | |||||
| 1103 | /// Return true if instruction I depends on any instruction between | ||||
| 1104 | /// Start and End. | ||||
| 1105 | bool LoopReroll::DAGRootTracker::instrDependsOn(Instruction *I, | ||||
| 1106 | UsesTy::iterator Start, | ||||
| 1107 | UsesTy::iterator End) { | ||||
| 1108 | for (auto *U : I->users()) { | ||||
| 1109 | for (auto It = Start; It != End; ++It) | ||||
| 1110 | if (U == It->first) | ||||
| 1111 | return true; | ||||
| 1112 | } | ||||
| 1113 | return false; | ||||
| 1114 | } | ||||
| 1115 | |||||
| 1116 | static bool isIgnorableInst(const Instruction *I) { | ||||
| 1117 | if (isa<DbgInfoIntrinsic>(I)) | ||||
| 1118 | return true; | ||||
| 1119 | const IntrinsicInst* II = dyn_cast<IntrinsicInst>(I); | ||||
| 1120 | if (!II) | ||||
| 1121 | return false; | ||||
| 1122 | switch (II->getIntrinsicID()) { | ||||
| 1123 | default: | ||||
| 1124 | return false; | ||||
| 1125 | case Intrinsic::annotation: | ||||
| 1126 | case Intrinsic::ptr_annotation: | ||||
| 1127 | case Intrinsic::var_annotation: | ||||
| 1128 | // TODO: the following intrinsics may also be whitelisted: | ||||
| 1129 | // lifetime_start, lifetime_end, invariant_start, invariant_end | ||||
| 1130 | return true; | ||||
| 1131 | } | ||||
| 1132 | return false; | ||||
| 1133 | } | ||||
| 1134 | |||||
| 1135 | bool LoopReroll::DAGRootTracker::validate(ReductionTracker &Reductions) { | ||||
| 1136 | // We now need to check for equivalence of the use graph of each root with | ||||
| 1137 | // that of the primary induction variable (excluding the roots). Our goal | ||||
| 1138 | // here is not to solve the full graph isomorphism problem, but rather to | ||||
| 1139 | // catch common cases without a lot of work. As a result, we will assume | ||||
| 1140 | // that the relative order of the instructions in each unrolled iteration | ||||
| 1141 | // is the same (although we will not make an assumption about how the | ||||
| 1142 | // different iterations are intermixed). Note that while the order must be | ||||
| 1143 | // the same, the instructions may not be in the same basic block. | ||||
| 1144 | |||||
| 1145 | // An array of just the possible reductions for this scale factor. When we | ||||
| 1146 | // collect the set of all users of some root instructions, these reduction | ||||
| 1147 | // instructions are treated as 'final' (their uses are not considered). | ||||
| 1148 | // This is important because we don't want the root use set to search down | ||||
| 1149 | // the reduction chain. | ||||
| 1150 | SmallInstructionSet PossibleRedSet; | ||||
| 1151 | SmallInstructionSet PossibleRedLastSet; | ||||
| 1152 | SmallInstructionSet PossibleRedPHISet; | ||||
| 1153 | Reductions.restrictToScale(Scale, PossibleRedSet, | ||||
| 1154 | PossibleRedPHISet, PossibleRedLastSet); | ||||
| 1155 | |||||
| 1156 | // Populate "Uses" with where each instruction is used. | ||||
| 1157 | if (!collectUsedInstructions(PossibleRedSet)) | ||||
| 1158 | return false; | ||||
| 1159 | |||||
| 1160 | // Make sure we mark the reduction PHIs as used in all iterations. | ||||
| 1161 | for (auto *I : PossibleRedPHISet) { | ||||
| 1162 | Uses[I].set(IL_All); | ||||
| 1163 | } | ||||
| 1164 | |||||
| 1165 | // Make sure we mark loop-control-only PHIs as used in all iterations. See | ||||
| 1166 | // comment above LoopReroll::isLoopControlIV for more information. | ||||
| 1167 | BasicBlock *Header = L->getHeader(); | ||||
| 1168 | if (LoopControlIV && LoopControlIV != IV) { | ||||
| 1169 | for (auto *U : LoopControlIV->users()) { | ||||
| 1170 | Instruction *IVUser = dyn_cast<Instruction>(U); | ||||
| 1171 | // IVUser could be loop increment or compare | ||||
| 1172 | Uses[IVUser].set(IL_All); | ||||
| 1173 | for (auto *UU : IVUser->users()) { | ||||
| 1174 | Instruction *UUser = dyn_cast<Instruction>(UU); | ||||
| 1175 | // UUser could be compare, PHI or branch | ||||
| 1176 | Uses[UUser].set(IL_All); | ||||
| 1177 | // Skip SExt | ||||
| 1178 | if (isa<SExtInst>(UUser)) { | ||||
| 1179 | UUser = dyn_cast<Instruction>(*(UUser->user_begin())); | ||||
| 1180 | Uses[UUser].set(IL_All); | ||||
| 1181 | } | ||||
| 1182 | // Is UUser a compare instruction? | ||||
| 1183 | if (UU->hasOneUse()) { | ||||
| 1184 | Instruction *BI = dyn_cast<BranchInst>(*UUser->user_begin()); | ||||
| 1185 | if (BI == cast<BranchInst>(Header->getTerminator())) | ||||
| 1186 | Uses[BI].set(IL_All); | ||||
| 1187 | } | ||||
| 1188 | } | ||||
| 1189 | } | ||||
| 1190 | } | ||||
| 1191 | |||||
| 1192 | // Make sure all instructions in the loop are in one and only one | ||||
| 1193 | // set. | ||||
| 1194 | for (auto &KV : Uses) { | ||||
| 1195 | if (KV.second.count() != 1 && !isIgnorableInst(KV.first)) { | ||||
| 1196 | LLVM_DEBUG(do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: Aborting - instruction is not used in 1 iteration: " << *KV.first << " (#uses=" << KV.second.count () << ")\n"; } } while (false) | ||||
| 1197 | dbgs() << "LRR: Aborting - instruction is not used in 1 iteration: "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: Aborting - instruction is not used in 1 iteration: " << *KV.first << " (#uses=" << KV.second.count () << ")\n"; } } while (false) | ||||
| 1198 | << *KV.first << " (#uses=" << KV.second.count() << ")\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: Aborting - instruction is not used in 1 iteration: " << *KV.first << " (#uses=" << KV.second.count () << ")\n"; } } while (false); | ||||
| 1199 | return false; | ||||
| 1200 | } | ||||
| 1201 | } | ||||
| 1202 | |||||
| 1203 | LLVM_DEBUG(for (auto &KVdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { for (auto &KV : Uses) { dbgs() << "LRR: " << KV.second.find_first() << "\t" << *KV.first << "\n"; }; } } while (false) | ||||
| 1204 | : Uses) {do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { for (auto &KV : Uses) { dbgs() << "LRR: " << KV.second.find_first() << "\t" << *KV.first << "\n"; }; } } while (false) | ||||
| 1205 | dbgs() << "LRR: " << KV.second.find_first() << "\t" << *KV.first << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { for (auto &KV : Uses) { dbgs() << "LRR: " << KV.second.find_first() << "\t" << *KV.first << "\n"; }; } } while (false) | ||||
| 1206 | })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { for (auto &KV : Uses) { dbgs() << "LRR: " << KV.second.find_first() << "\t" << *KV.first << "\n"; }; } } while (false); | ||||
| 1207 | |||||
| 1208 | for (unsigned Iter = 1; Iter < Scale; ++Iter) { | ||||
| 1209 | // In addition to regular aliasing information, we need to look for | ||||
| 1210 | // instructions from later (future) iterations that have side effects | ||||
| 1211 | // preventing us from reordering them past other instructions with side | ||||
| 1212 | // effects. | ||||
| 1213 | bool FutureSideEffects = false; | ||||
| 1214 | AliasSetTracker AST(*AA); | ||||
| 1215 | // The map between instructions in f(%iv.(i+1)) and f(%iv). | ||||
| 1216 | DenseMap<Value *, Value *> BaseMap; | ||||
| 1217 | |||||
| 1218 | // Compare iteration Iter to the base. | ||||
| 1219 | SmallInstructionSet Visited; | ||||
| 1220 | auto BaseIt = nextInstr(0, Uses, Visited); | ||||
| 1221 | auto RootIt = nextInstr(Iter, Uses, Visited); | ||||
| 1222 | auto LastRootIt = Uses.begin(); | ||||
| 1223 | |||||
| 1224 | while (BaseIt != Uses.end() && RootIt != Uses.end()) { | ||||
| 1225 | Instruction *BaseInst = BaseIt->first; | ||||
| 1226 | Instruction *RootInst = RootIt->first; | ||||
| 1227 | |||||
| 1228 | // Skip over the IV or root instructions; only match their users. | ||||
| 1229 | bool Continue = false; | ||||
| 1230 | if (isBaseInst(BaseInst)) { | ||||
| 1231 | Visited.insert(BaseInst); | ||||
| 1232 | BaseIt = nextInstr(0, Uses, Visited); | ||||
| 1233 | Continue = true; | ||||
| 1234 | } | ||||
| 1235 | if (isRootInst(RootInst)) { | ||||
| 1236 | LastRootIt = RootIt; | ||||
| 1237 | Visited.insert(RootInst); | ||||
| 1238 | RootIt = nextInstr(Iter, Uses, Visited); | ||||
| 1239 | Continue = true; | ||||
| 1240 | } | ||||
| 1241 | if (Continue) continue; | ||||
| 1242 | |||||
| 1243 | if (!BaseInst->isSameOperationAs(RootInst)) { | ||||
| 1244 | // Last chance saloon. We don't try and solve the full isomorphism | ||||
| 1245 | // problem, but try and at least catch the case where two instructions | ||||
| 1246 | // *of different types* are round the wrong way. We won't be able to | ||||
| 1247 | // efficiently tell, given two ADD instructions, which way around we | ||||
| 1248 | // should match them, but given an ADD and a SUB, we can at least infer | ||||
| 1249 | // which one is which. | ||||
| 1250 | // | ||||
| 1251 | // This should allow us to deal with a greater subset of the isomorphism | ||||
| 1252 | // problem. It does however change a linear algorithm into a quadratic | ||||
| 1253 | // one, so limit the number of probes we do. | ||||
| 1254 | auto TryIt = RootIt; | ||||
| 1255 | unsigned N = NumToleratedFailedMatches; | ||||
| 1256 | while (TryIt != Uses.end() && | ||||
| 1257 | !BaseInst->isSameOperationAs(TryIt->first) && | ||||
| 1258 | N--) { | ||||
| 1259 | ++TryIt; | ||||
| 1260 | TryIt = nextInstr(Iter, Uses, Visited, &TryIt); | ||||
| 1261 | } | ||||
| 1262 | |||||
| 1263 | if (TryIt == Uses.end() || TryIt == RootIt || | ||||
| 1264 | instrDependsOn(TryIt->first, RootIt, TryIt)) { | ||||
| 1265 | LLVM_DEBUG(dbgs() << "LRR: iteration root match failed at "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: iteration root match failed at " << *BaseInst << " vs. " << *RootInst << "\n"; } } while (false) | ||||
| 1266 | << *BaseInst << " vs. " << *RootInst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: iteration root match failed at " << *BaseInst << " vs. " << *RootInst << "\n"; } } while (false); | ||||
| 1267 | return false; | ||||
| 1268 | } | ||||
| 1269 | |||||
| 1270 | RootIt = TryIt; | ||||
| 1271 | RootInst = TryIt->first; | ||||
| 1272 | } | ||||
| 1273 | |||||
| 1274 | // All instructions between the last root and this root | ||||
| 1275 | // may belong to some other iteration. If they belong to a | ||||
| 1276 | // future iteration, then they're dangerous to alias with. | ||||
| 1277 | // | ||||
| 1278 | // Note that because we allow a limited amount of flexibility in the order | ||||
| 1279 | // that we visit nodes, LastRootIt might be *before* RootIt, in which | ||||
| 1280 | // case we've already checked this set of instructions so we shouldn't | ||||
| 1281 | // do anything. | ||||
| 1282 | for (; LastRootIt < RootIt; ++LastRootIt) { | ||||
| 1283 | Instruction *I = LastRootIt->first; | ||||
| 1284 | if (LastRootIt->second.find_first() < (int)Iter) | ||||
| 1285 | continue; | ||||
| 1286 | if (I->mayWriteToMemory()) | ||||
| 1287 | AST.add(I); | ||||
| 1288 | // Note: This is specifically guarded by a check on isa<PHINode>, | ||||
| 1289 | // which while a valid (somewhat arbitrary) micro-optimization, is | ||||
| 1290 | // needed because otherwise isSafeToSpeculativelyExecute returns | ||||
| 1291 | // false on PHI nodes. | ||||
| 1292 | if (!isa<PHINode>(I) && !isUnorderedLoadStore(I) && | ||||
| 1293 | !isSafeToSpeculativelyExecute(I)) | ||||
| 1294 | // Intervening instructions cause side effects. | ||||
| 1295 | FutureSideEffects = true; | ||||
| 1296 | } | ||||
| 1297 | |||||
| 1298 | // Make sure that this instruction, which is in the use set of this | ||||
| 1299 | // root instruction, does not also belong to the base set or the set of | ||||
| 1300 | // some other root instruction. | ||||
| 1301 | if (RootIt->second.count() > 1) { | ||||
| 1302 | LLVM_DEBUG(dbgs() << "LRR: iteration root match failed at " << *BaseInstdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: iteration root match failed at " << *BaseInst << " vs. " << *RootInst << " (prev. case overlap)\n"; } } while (false) | ||||
| 1303 | << " vs. " << *RootInst << " (prev. case overlap)\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: iteration root match failed at " << *BaseInst << " vs. " << *RootInst << " (prev. case overlap)\n"; } } while (false); | ||||
| 1304 | return false; | ||||
| 1305 | } | ||||
| 1306 | |||||
| 1307 | // Make sure that we don't alias with any instruction in the alias set | ||||
| 1308 | // tracker. If we do, then we depend on a future iteration, and we | ||||
| 1309 | // can't reroll. | ||||
| 1310 | if (RootInst->mayReadFromMemory()) | ||||
| 1311 | for (auto &K : AST) { | ||||
| 1312 | if (K.aliasesUnknownInst(RootInst, *AA)) { | ||||
| 1313 | LLVM_DEBUG(dbgs() << "LRR: iteration root match failed at "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: iteration root match failed at " << *BaseInst << " vs. " << *RootInst << " (depends on future store)\n"; } } while (false) | ||||
| 1314 | << *BaseInst << " vs. " << *RootInstdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: iteration root match failed at " << *BaseInst << " vs. " << *RootInst << " (depends on future store)\n"; } } while (false) | ||||
| 1315 | << " (depends on future store)\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: iteration root match failed at " << *BaseInst << " vs. " << *RootInst << " (depends on future store)\n"; } } while (false); | ||||
| 1316 | return false; | ||||
| 1317 | } | ||||
| 1318 | } | ||||
| 1319 | |||||
| 1320 | // If we've past an instruction from a future iteration that may have | ||||
| 1321 | // side effects, and this instruction might also, then we can't reorder | ||||
| 1322 | // them, and this matching fails. As an exception, we allow the alias | ||||
| 1323 | // set tracker to handle regular (unordered) load/store dependencies. | ||||
| 1324 | if (FutureSideEffects && ((!isUnorderedLoadStore(BaseInst) && | ||||
| 1325 | !isSafeToSpeculativelyExecute(BaseInst)) || | ||||
| 1326 | (!isUnorderedLoadStore(RootInst) && | ||||
| 1327 | !isSafeToSpeculativelyExecute(RootInst)))) { | ||||
| 1328 | LLVM_DEBUG(dbgs() << "LRR: iteration root match failed at " << *BaseInstdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: iteration root match failed at " << *BaseInst << " vs. " << *RootInst << " (side effects prevent reordering)\n"; } } while (false) | ||||
| 1329 | << " vs. " << *RootInstdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: iteration root match failed at " << *BaseInst << " vs. " << *RootInst << " (side effects prevent reordering)\n"; } } while (false) | ||||
| 1330 | << " (side effects prevent reordering)\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: iteration root match failed at " << *BaseInst << " vs. " << *RootInst << " (side effects prevent reordering)\n"; } } while (false); | ||||
| 1331 | return false; | ||||
| 1332 | } | ||||
| 1333 | |||||
| 1334 | // For instructions that are part of a reduction, if the operation is | ||||
| 1335 | // associative, then don't bother matching the operands (because we | ||||
| 1336 | // already know that the instructions are isomorphic, and the order | ||||
| 1337 | // within the iteration does not matter). For non-associative reductions, | ||||
| 1338 | // we do need to match the operands, because we need to reject | ||||
| 1339 | // out-of-order instructions within an iteration! | ||||
| 1340 | // For example (assume floating-point addition), we need to reject this: | ||||
| 1341 | // x += a[i]; x += b[i]; | ||||
| 1342 | // x += a[i+1]; x += b[i+1]; | ||||
| 1343 | // x += b[i+2]; x += a[i+2]; | ||||
| 1344 | bool InReduction = Reductions.isPairInSame(BaseInst, RootInst); | ||||
| 1345 | |||||
| 1346 | if (!(InReduction && BaseInst->isAssociative())) { | ||||
| 1347 | bool Swapped = false, SomeOpMatched = false; | ||||
| 1348 | for (unsigned j = 0; j < BaseInst->getNumOperands(); ++j) { | ||||
| 1349 | Value *Op2 = RootInst->getOperand(j); | ||||
| 1350 | |||||
| 1351 | // If this is part of a reduction (and the operation is not | ||||
| 1352 | // associatve), then we match all operands, but not those that are | ||||
| 1353 | // part of the reduction. | ||||
| 1354 | if (InReduction) | ||||
| 1355 | if (Instruction *Op2I = dyn_cast<Instruction>(Op2)) | ||||
| 1356 | if (Reductions.isPairInSame(RootInst, Op2I)) | ||||
| 1357 | continue; | ||||
| 1358 | |||||
| 1359 | DenseMap<Value *, Value *>::iterator BMI = BaseMap.find(Op2); | ||||
| 1360 | if (BMI != BaseMap.end()) { | ||||
| 1361 | Op2 = BMI->second; | ||||
| 1362 | } else { | ||||
| 1363 | for (auto &DRS : RootSets) { | ||||
| 1364 | if (DRS.Roots[Iter-1] == (Instruction*) Op2) { | ||||
| 1365 | Op2 = DRS.BaseInst; | ||||
| 1366 | break; | ||||
| 1367 | } | ||||
| 1368 | } | ||||
| 1369 | } | ||||
| 1370 | |||||
| 1371 | if (BaseInst->getOperand(Swapped ? unsigned(!j) : j) != Op2) { | ||||
| 1372 | // If we've not already decided to swap the matched operands, and | ||||
| 1373 | // we've not already matched our first operand (note that we could | ||||
| 1374 | // have skipped matching the first operand because it is part of a | ||||
| 1375 | // reduction above), and the instruction is commutative, then try | ||||
| 1376 | // the swapped match. | ||||
| 1377 | if (!Swapped && BaseInst->isCommutative() && !SomeOpMatched && | ||||
| 1378 | BaseInst->getOperand(!j) == Op2) { | ||||
| 1379 | Swapped = true; | ||||
| 1380 | } else { | ||||
| 1381 | LLVM_DEBUG(dbgs()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: iteration root match failed at " << *BaseInst << " vs. " << *RootInst << " (operand " << j << ")\n"; } } while (false) | ||||
| 1382 | << "LRR: iteration root match failed at " << *BaseInstdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: iteration root match failed at " << *BaseInst << " vs. " << *RootInst << " (operand " << j << ")\n"; } } while (false) | ||||
| 1383 | << " vs. " << *RootInst << " (operand " << j << ")\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: iteration root match failed at " << *BaseInst << " vs. " << *RootInst << " (operand " << j << ")\n"; } } while (false); | ||||
| 1384 | return false; | ||||
| 1385 | } | ||||
| 1386 | } | ||||
| 1387 | |||||
| 1388 | SomeOpMatched = true; | ||||
| 1389 | } | ||||
| 1390 | } | ||||
| 1391 | |||||
| 1392 | if ((!PossibleRedLastSet.count(BaseInst) && | ||||
| 1393 | hasUsesOutsideLoop(BaseInst, L)) || | ||||
| 1394 | (!PossibleRedLastSet.count(RootInst) && | ||||
| 1395 | hasUsesOutsideLoop(RootInst, L))) { | ||||
| 1396 | LLVM_DEBUG(dbgs() << "LRR: iteration root match failed at " << *BaseInstdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: iteration root match failed at " << *BaseInst << " vs. " << *RootInst << " (uses outside loop)\n"; } } while (false) | ||||
| 1397 | << " vs. " << *RootInst << " (uses outside loop)\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: iteration root match failed at " << *BaseInst << " vs. " << *RootInst << " (uses outside loop)\n"; } } while (false); | ||||
| 1398 | return false; | ||||
| 1399 | } | ||||
| 1400 | |||||
| 1401 | Reductions.recordPair(BaseInst, RootInst, Iter); | ||||
| 1402 | BaseMap.insert(std::make_pair(RootInst, BaseInst)); | ||||
| 1403 | |||||
| 1404 | LastRootIt = RootIt; | ||||
| 1405 | Visited.insert(BaseInst); | ||||
| 1406 | Visited.insert(RootInst); | ||||
| 1407 | BaseIt = nextInstr(0, Uses, Visited); | ||||
| 1408 | RootIt = nextInstr(Iter, Uses, Visited); | ||||
| 1409 | } | ||||
| 1410 | assert(BaseIt == Uses.end() && RootIt == Uses.end() &&((BaseIt == Uses.end() && RootIt == Uses.end() && "Mismatched set sizes!") ? static_cast<void> (0) : __assert_fail ("BaseIt == Uses.end() && RootIt == Uses.end() && \"Mismatched set sizes!\"" , "/build/llvm-toolchain-snapshot-10~svn374814/lib/Transforms/Scalar/LoopRerollPass.cpp" , 1411, __PRETTY_FUNCTION__)) | ||||
| 1411 | "Mismatched set sizes!")((BaseIt == Uses.end() && RootIt == Uses.end() && "Mismatched set sizes!") ? static_cast<void> (0) : __assert_fail ("BaseIt == Uses.end() && RootIt == Uses.end() && \"Mismatched set sizes!\"" , "/build/llvm-toolchain-snapshot-10~svn374814/lib/Transforms/Scalar/LoopRerollPass.cpp" , 1411, __PRETTY_FUNCTION__)); | ||||
| 1412 | } | ||||
| 1413 | |||||
| 1414 | LLVM_DEBUG(dbgs() << "LRR: Matched all iteration increments for " << *IVdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: Matched all iteration increments for " << *IV << "\n"; } } while (false) | ||||
| 1415 | << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: Matched all iteration increments for " << *IV << "\n"; } } while (false); | ||||
| 1416 | |||||
| 1417 | return true; | ||||
| 1418 | } | ||||
| 1419 | |||||
| 1420 | void LoopReroll::DAGRootTracker::replace(const SCEV *BackedgeTakenCount) { | ||||
| 1421 | BasicBlock *Header = L->getHeader(); | ||||
| 1422 | |||||
| 1423 | // Compute the start and increment for each BaseInst before we start erasing | ||||
| 1424 | // instructions. | ||||
| 1425 | SmallVector<const SCEV *, 8> StartExprs; | ||||
| 1426 | SmallVector<const SCEV *, 8> IncrExprs; | ||||
| 1427 | for (auto &DRS : RootSets) { | ||||
| 1428 | const SCEVAddRecExpr *IVSCEV = | ||||
| 1429 | cast<SCEVAddRecExpr>(SE->getSCEV(DRS.BaseInst)); | ||||
| 1430 | StartExprs.push_back(IVSCEV->getStart()); | ||||
| 1431 | IncrExprs.push_back(SE->getMinusSCEV(SE->getSCEV(DRS.Roots[0]), IVSCEV)); | ||||
| 1432 | } | ||||
| 1433 | |||||
| 1434 | // Remove instructions associated with non-base iterations. | ||||
| 1435 | for (BasicBlock::reverse_iterator J = Header->rbegin(), JE = Header->rend(); | ||||
| 1436 | J != JE;) { | ||||
| 1437 | unsigned I = Uses[&*J].find_first(); | ||||
| 1438 | if (I > 0 && I < IL_All) { | ||||
| 1439 | LLVM_DEBUG(dbgs() << "LRR: removing: " << *J << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: removing: " << *J << "\n"; } } while (false); | ||||
| 1440 | J++->eraseFromParent(); | ||||
| 1441 | continue; | ||||
| 1442 | } | ||||
| 1443 | |||||
| 1444 | ++J; | ||||
| 1445 | } | ||||
| 1446 | |||||
| 1447 | // Rewrite each BaseInst using SCEV. | ||||
| 1448 | for (size_t i = 0, e = RootSets.size(); i != e; ++i) | ||||
| 1449 | // Insert the new induction variable. | ||||
| 1450 | replaceIV(RootSets[i], StartExprs[i], IncrExprs[i]); | ||||
| 1451 | |||||
| 1452 | { // Limit the lifetime of SCEVExpander. | ||||
| 1453 | BranchInst *BI = cast<BranchInst>(Header->getTerminator()); | ||||
| 1454 | const DataLayout &DL = Header->getModule()->getDataLayout(); | ||||
| 1455 | SCEVExpander Expander(*SE, DL, "reroll"); | ||||
| 1456 | auto Zero = SE->getZero(BackedgeTakenCount->getType()); | ||||
| 1457 | auto One = SE->getOne(BackedgeTakenCount->getType()); | ||||
| 1458 | auto NewIVSCEV = SE->getAddRecExpr(Zero, One, L, SCEV::FlagAnyWrap); | ||||
| 1459 | Value *NewIV = | ||||
| 1460 | Expander.expandCodeFor(NewIVSCEV, BackedgeTakenCount->getType(), | ||||
| 1461 | Header->getFirstNonPHIOrDbg()); | ||||
| 1462 | // FIXME: This arithmetic can overflow. | ||||
| 1463 | auto TripCount = SE->getAddExpr(BackedgeTakenCount, One); | ||||
| 1464 | auto ScaledTripCount = SE->getMulExpr( | ||||
| 1465 | TripCount, SE->getConstant(BackedgeTakenCount->getType(), Scale)); | ||||
| 1466 | auto ScaledBECount = SE->getMinusSCEV(ScaledTripCount, One); | ||||
| 1467 | Value *TakenCount = | ||||
| 1468 | Expander.expandCodeFor(ScaledBECount, BackedgeTakenCount->getType(), | ||||
| 1469 | Header->getFirstNonPHIOrDbg()); | ||||
| 1470 | Value *Cond = | ||||
| 1471 | new ICmpInst(BI, CmpInst::ICMP_EQ, NewIV, TakenCount, "exitcond"); | ||||
| 1472 | BI->setCondition(Cond); | ||||
| 1473 | |||||
| 1474 | if (BI->getSuccessor(1) != Header) | ||||
| 1475 | BI->swapSuccessors(); | ||||
| 1476 | } | ||||
| 1477 | |||||
| 1478 | SimplifyInstructionsInBlock(Header, TLI); | ||||
| 1479 | DeleteDeadPHIs(Header, TLI); | ||||
| 1480 | } | ||||
| 1481 | |||||
| 1482 | void LoopReroll::DAGRootTracker::replaceIV(DAGRootSet &DRS, | ||||
| 1483 | const SCEV *Start, | ||||
| 1484 | const SCEV *IncrExpr) { | ||||
| 1485 | BasicBlock *Header = L->getHeader(); | ||||
| 1486 | Instruction *Inst = DRS.BaseInst; | ||||
| 1487 | |||||
| 1488 | const SCEV *NewIVSCEV = | ||||
| 1489 | SE->getAddRecExpr(Start, IncrExpr, L, SCEV::FlagAnyWrap); | ||||
| 1490 | |||||
| 1491 | { // Limit the lifetime of SCEVExpander. | ||||
| 1492 | const DataLayout &DL = Header->getModule()->getDataLayout(); | ||||
| 1493 | SCEVExpander Expander(*SE, DL, "reroll"); | ||||
| 1494 | Value *NewIV = Expander.expandCodeFor(NewIVSCEV, Inst->getType(), | ||||
| 1495 | Header->getFirstNonPHIOrDbg()); | ||||
| 1496 | |||||
| 1497 | for (auto &KV : Uses) | ||||
| 1498 | if (KV.second.find_first() == 0) | ||||
| 1499 | KV.first->replaceUsesOfWith(Inst, NewIV); | ||||
| 1500 | } | ||||
| 1501 | } | ||||
| 1502 | |||||
| 1503 | // Validate the selected reductions. All iterations must have an isomorphic | ||||
| 1504 | // part of the reduction chain and, for non-associative reductions, the chain | ||||
| 1505 | // entries must appear in order. | ||||
| 1506 | bool LoopReroll::ReductionTracker::validateSelected() { | ||||
| 1507 | // For a non-associative reduction, the chain entries must appear in order. | ||||
| 1508 | for (int i : Reds) { | ||||
| 1509 | int PrevIter = 0, BaseCount = 0, Count = 0; | ||||
| 1510 | for (Instruction *J : PossibleReds[i]) { | ||||
| 1511 | // Note that all instructions in the chain must have been found because | ||||
| 1512 | // all instructions in the function must have been assigned to some | ||||
| 1513 | // iteration. | ||||
| 1514 | int Iter = PossibleRedIter[J]; | ||||
| 1515 | if (Iter != PrevIter && Iter != PrevIter + 1 && | ||||
| 1516 | !PossibleReds[i].getReducedValue()->isAssociative()) { | ||||
| 1517 | LLVM_DEBUG(dbgs() << "LRR: Out-of-order non-associative reduction: "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: Out-of-order non-associative reduction: " << J << "\n"; } } while (false) | ||||
| 1518 | << J << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: Out-of-order non-associative reduction: " << J << "\n"; } } while (false); | ||||
| 1519 | return false; | ||||
| 1520 | } | ||||
| 1521 | |||||
| 1522 | if (Iter != PrevIter) { | ||||
| 1523 | if (Count != BaseCount) { | ||||
| 1524 | LLVM_DEBUG(dbgs()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: Iteration " << PrevIter << " reduction use count " << Count << " is not equal to the base use count " << BaseCount << "\n"; } } while (false) | ||||
| 1525 | << "LRR: Iteration " << PrevIter << " reduction use count "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: Iteration " << PrevIter << " reduction use count " << Count << " is not equal to the base use count " << BaseCount << "\n"; } } while (false) | ||||
| 1526 | << Count << " is not equal to the base use count "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: Iteration " << PrevIter << " reduction use count " << Count << " is not equal to the base use count " << BaseCount << "\n"; } } while (false) | ||||
| 1527 | << BaseCount << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: Iteration " << PrevIter << " reduction use count " << Count << " is not equal to the base use count " << BaseCount << "\n"; } } while (false); | ||||
| 1528 | return false; | ||||
| 1529 | } | ||||
| 1530 | |||||
| 1531 | Count = 0; | ||||
| 1532 | } | ||||
| 1533 | |||||
| 1534 | ++Count; | ||||
| 1535 | if (Iter == 0) | ||||
| 1536 | ++BaseCount; | ||||
| 1537 | |||||
| 1538 | PrevIter = Iter; | ||||
| 1539 | } | ||||
| 1540 | } | ||||
| 1541 | |||||
| 1542 | return true; | ||||
| 1543 | } | ||||
| 1544 | |||||
| 1545 | // For all selected reductions, remove all parts except those in the first | ||||
| 1546 | // iteration (and the PHI). Replace outside uses of the reduced value with uses | ||||
| 1547 | // of the first-iteration reduced value (in other words, reroll the selected | ||||
| 1548 | // reductions). | ||||
| 1549 | void LoopReroll::ReductionTracker::replaceSelected() { | ||||
| 1550 | // Fixup reductions to refer to the last instruction associated with the | ||||
| 1551 | // first iteration (not the last). | ||||
| 1552 | for (int i : Reds) { | ||||
| 1553 | int j = 0; | ||||
| 1554 | for (int e = PossibleReds[i].size(); j != e; ++j) | ||||
| 1555 | if (PossibleRedIter[PossibleReds[i][j]] != 0) { | ||||
| 1556 | --j; | ||||
| 1557 | break; | ||||
| 1558 | } | ||||
| 1559 | |||||
| 1560 | // Replace users with the new end-of-chain value. | ||||
| 1561 | SmallInstructionVector Users; | ||||
| 1562 | for (User *U : PossibleReds[i].getReducedValue()->users()) { | ||||
| 1563 | Users.push_back(cast<Instruction>(U)); | ||||
| 1564 | } | ||||
| 1565 | |||||
| 1566 | for (Instruction *User : Users) | ||||
| 1567 | User->replaceUsesOfWith(PossibleReds[i].getReducedValue(), | ||||
| 1568 | PossibleReds[i][j]); | ||||
| 1569 | } | ||||
| 1570 | } | ||||
| 1571 | |||||
| 1572 | // Reroll the provided loop with respect to the provided induction variable. | ||||
| 1573 | // Generally, we're looking for a loop like this: | ||||
| 1574 | // | ||||
| 1575 | // %iv = phi [ (preheader, ...), (body, %iv.next) ] | ||||
| 1576 | // f(%iv) | ||||
| 1577 | // %iv.1 = add %iv, 1 <-- a root increment | ||||
| 1578 | // f(%iv.1) | ||||
| 1579 | // %iv.2 = add %iv, 2 <-- a root increment | ||||
| 1580 | // f(%iv.2) | ||||
| 1581 | // %iv.scale_m_1 = add %iv, scale-1 <-- a root increment | ||||
| 1582 | // f(%iv.scale_m_1) | ||||
| 1583 | // ... | ||||
| 1584 | // %iv.next = add %iv, scale | ||||
| 1585 | // %cmp = icmp(%iv, ...) | ||||
| 1586 | // br %cmp, header, exit | ||||
| 1587 | // | ||||
| 1588 | // Notably, we do not require that f(%iv), f(%iv.1), etc. be isolated groups of | ||||
| 1589 | // instructions. In other words, the instructions in f(%iv), f(%iv.1), etc. can | ||||
| 1590 | // be intermixed with eachother. The restriction imposed by this algorithm is | ||||
| 1591 | // that the relative order of the isomorphic instructions in f(%iv), f(%iv.1), | ||||
| 1592 | // etc. be the same. | ||||
| 1593 | // | ||||
| 1594 | // First, we collect the use set of %iv, excluding the other increment roots. | ||||
| 1595 | // This gives us f(%iv). Then we iterate over the loop instructions (scale-1) | ||||
| 1596 | // times, having collected the use set of f(%iv.(i+1)), during which we: | ||||
| 1597 | // - Ensure that the next unmatched instruction in f(%iv) is isomorphic to | ||||
| 1598 | // the next unmatched instruction in f(%iv.(i+1)). | ||||
| 1599 | // - Ensure that both matched instructions don't have any external users | ||||
| 1600 | // (with the exception of last-in-chain reduction instructions). | ||||
| 1601 | // - Track the (aliasing) write set, and other side effects, of all | ||||
| 1602 | // instructions that belong to future iterations that come before the matched | ||||
| 1603 | // instructions. If the matched instructions read from that write set, then | ||||
| 1604 | // f(%iv) or f(%iv.(i+1)) has some dependency on instructions in | ||||
| 1605 | // f(%iv.(j+1)) for some j > i, and we cannot reroll the loop. Similarly, | ||||
| 1606 | // if any of these future instructions had side effects (could not be | ||||
| 1607 | // speculatively executed), and so do the matched instructions, when we | ||||
| 1608 | // cannot reorder those side-effect-producing instructions, and rerolling | ||||
| 1609 | // fails. | ||||
| 1610 | // | ||||
| 1611 | // Finally, we make sure that all loop instructions are either loop increment | ||||
| 1612 | // roots, belong to simple latch code, parts of validated reductions, part of | ||||
| 1613 | // f(%iv) or part of some f(%iv.i). If all of that is true (and all reductions | ||||
| 1614 | // have been validated), then we reroll the loop. | ||||
| 1615 | bool LoopReroll::reroll(Instruction *IV, Loop *L, BasicBlock *Header, | ||||
| 1616 | const SCEV *BackedgeTakenCount, | ||||
| 1617 | ReductionTracker &Reductions) { | ||||
| 1618 | DAGRootTracker DAGRoots(this, L, IV, SE, AA, TLI, DT, LI, PreserveLCSSA, | ||||
| 1619 | IVToIncMap, LoopControlIV); | ||||
| 1620 | |||||
| 1621 | if (!DAGRoots.findRoots()) | ||||
| 1622 | return false; | ||||
| 1623 | LLVM_DEBUG(dbgs() << "LRR: Found all root induction increments for: " << *IVdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: Found all root induction increments for: " << *IV << "\n"; } } while (false) | ||||
| 1624 | << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: Found all root induction increments for: " << *IV << "\n"; } } while (false); | ||||
| 1625 | |||||
| 1626 | if (!DAGRoots.validate(Reductions)) | ||||
| 1627 | return false; | ||||
| 1628 | if (!Reductions.validateSelected()) | ||||
| 1629 | return false; | ||||
| 1630 | // At this point, we've validated the rerolling, and we're committed to | ||||
| 1631 | // making changes! | ||||
| 1632 | |||||
| 1633 | Reductions.replaceSelected(); | ||||
| 1634 | DAGRoots.replace(BackedgeTakenCount); | ||||
| 1635 | |||||
| 1636 | ++NumRerolledLoops; | ||||
| 1637 | return true; | ||||
| 1638 | } | ||||
| 1639 | |||||
| 1640 | bool LoopReroll::runOnLoop(Loop *L, LPPassManager &LPM) { | ||||
| 1641 | if (skipLoop(L)) | ||||
| |||||
| 1642 | return false; | ||||
| 1643 | |||||
| 1644 | AA = &getAnalysis<AAResultsWrapperPass>().getAAResults(); | ||||
| 1645 | LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo(); | ||||
| 1646 | SE = &getAnalysis<ScalarEvolutionWrapperPass>().getSE(); | ||||
| 1647 | TLI = &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI( | ||||
| 1648 | *L->getHeader()->getParent()); | ||||
| 1649 | DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree(); | ||||
| 1650 | PreserveLCSSA = mustPreserveAnalysisID(LCSSAID); | ||||
| 1651 | |||||
| 1652 | BasicBlock *Header = L->getHeader(); | ||||
| 1653 | LLVM_DEBUG(dbgs() << "LRR: F[" << Header->getParent()->getName() << "] Loop %"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: F[" << Header-> getParent()->getName() << "] Loop %" << Header ->getName() << " (" << L->getNumBlocks() << " block(s))\n"; } } while (false) | ||||
| 1654 | << Header->getName() << " (" << L->getNumBlocks()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: F[" << Header-> getParent()->getName() << "] Loop %" << Header ->getName() << " (" << L->getNumBlocks() << " block(s))\n"; } } while (false) | ||||
| 1655 | << " block(s))\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: F[" << Header-> getParent()->getName() << "] Loop %" << Header ->getName() << " (" << L->getNumBlocks() << " block(s))\n"; } } while (false); | ||||
| 1656 | |||||
| 1657 | // For now, we'll handle only single BB loops. | ||||
| 1658 | if (L->getNumBlocks() > 1) | ||||
| 1659 | return false; | ||||
| 1660 | |||||
| 1661 | if (!SE->hasLoopInvariantBackedgeTakenCount(L)) | ||||
| 1662 | return false; | ||||
| 1663 | |||||
| 1664 | const SCEV *BackedgeTakenCount = SE->getBackedgeTakenCount(L); | ||||
| 1665 | LLVM_DEBUG(dbgs() << "\n Before Reroll:\n" << *(L->getHeader()) << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "\n Before Reroll:\n" << *(L->getHeader()) << "\n"; } } while (false); | ||||
| 1666 | LLVM_DEBUG
("loop-reroll")) { dbgs() << "LRR: backedge-taken count = " << *BackedgeTakenCount << "\n"; } } while (false ) | ||||
| 1667 | << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: backedge-taken count = " << *BackedgeTakenCount << "\n"; } } while (false ); | ||||
| 1668 | |||||
| 1669 | // First, we need to find the induction variable with respect to which we can | ||||
| 1670 | // reroll (there may be several possible options). | ||||
| 1671 | SmallInstructionVector PossibleIVs; | ||||
| 1672 | IVToIncMap.clear(); | ||||
| 1673 | LoopControlIV = nullptr; | ||||
| 1674 | collectPossibleIVs(L, PossibleIVs); | ||||
| 1675 | |||||
| 1676 | if (PossibleIVs.empty()) { | ||||
| 1677 | LLVM_DEBUG(dbgs() << "LRR: No possible IVs found\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "LRR: No possible IVs found\n" ; } } while (false); | ||||
| 1678 | return false; | ||||
| 1679 | } | ||||
| 1680 | |||||
| 1681 | ReductionTracker Reductions; | ||||
| 1682 | collectPossibleReductions(L, Reductions); | ||||
| 1683 | bool Changed = false; | ||||
| 1684 | |||||
| 1685 | // For each possible IV, collect the associated possible set of 'root' nodes | ||||
| 1686 | // (i+1, i+2, etc.). | ||||
| 1687 | for (Instruction *PossibleIV : PossibleIVs) | ||||
| 1688 | if (reroll(PossibleIV, L, Header, BackedgeTakenCount, Reductions)) { | ||||
| 1689 | Changed = true; | ||||
| 1690 | break; | ||||
| 1691 | } | ||||
| 1692 | LLVM_DEBUG(dbgs() << "\n After Reroll:\n" << *(L->getHeader()) << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reroll")) { dbgs() << "\n After Reroll:\n" << *(L->getHeader()) << "\n"; } } while (false); | ||||
| 1693 | |||||
| 1694 | // Trip count of L has changed so SE must be re-evaluated. | ||||
| 1695 | if (Changed) | ||||
| 1696 | SE->forgetLoop(L); | ||||
| 1697 | |||||
| 1698 | return Changed; | ||||
| 1699 | } |