LLVM  10.0.0svn
CodeGenPrepare.cpp
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1 //===- CodeGenPrepare.cpp - Prepare a function for code generation --------===//
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 munges the code in the input function to better prepare it for
10 // SelectionDAG-based code generation. This works around limitations in it's
11 // basic-block-at-a-time approach. It should eventually be removed.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "llvm/ADT/APInt.h"
16 #include "llvm/ADT/ArrayRef.h"
17 #include "llvm/ADT/DenseMap.h"
18 #include "llvm/ADT/MapVector.h"
20 #include "llvm/ADT/STLExtras.h"
21 #include "llvm/ADT/SmallPtrSet.h"
22 #include "llvm/ADT/SmallVector.h"
23 #include "llvm/ADT/Statistic.h"
28 #include "llvm/Analysis/LoopInfo.h"
36 #include "llvm/CodeGen/Analysis.h"
43 #include "llvm/Config/llvm-config.h"
44 #include "llvm/IR/Argument.h"
45 #include "llvm/IR/Attributes.h"
46 #include "llvm/IR/BasicBlock.h"
47 #include "llvm/IR/CallSite.h"
48 #include "llvm/IR/Constant.h"
49 #include "llvm/IR/Constants.h"
50 #include "llvm/IR/DataLayout.h"
51 #include "llvm/IR/DerivedTypes.h"
52 #include "llvm/IR/Dominators.h"
53 #include "llvm/IR/Function.h"
55 #include "llvm/IR/GlobalValue.h"
56 #include "llvm/IR/GlobalVariable.h"
57 #include "llvm/IR/IRBuilder.h"
58 #include "llvm/IR/InlineAsm.h"
59 #include "llvm/IR/InstrTypes.h"
60 #include "llvm/IR/Instruction.h"
61 #include "llvm/IR/Instructions.h"
62 #include "llvm/IR/IntrinsicInst.h"
63 #include "llvm/IR/Intrinsics.h"
64 #include "llvm/IR/LLVMContext.h"
65 #include "llvm/IR/MDBuilder.h"
66 #include "llvm/IR/Module.h"
67 #include "llvm/IR/Operator.h"
68 #include "llvm/IR/PatternMatch.h"
69 #include "llvm/IR/Statepoint.h"
70 #include "llvm/IR/Type.h"
71 #include "llvm/IR/Use.h"
72 #include "llvm/IR/User.h"
73 #include "llvm/IR/Value.h"
74 #include "llvm/IR/ValueHandle.h"
75 #include "llvm/IR/ValueMap.h"
76 #include "llvm/Pass.h"
79 #include "llvm/Support/Casting.h"
81 #include "llvm/Support/Compiler.h"
82 #include "llvm/Support/Debug.h"
92 #include <algorithm>
93 #include <cassert>
94 #include <cstdint>
95 #include <iterator>
96 #include <limits>
97 #include <memory>
98 #include <utility>
99 #include <vector>
100 
101 using namespace llvm;
102 using namespace llvm::PatternMatch;
103 
104 #define DEBUG_TYPE "codegenprepare"
105 
106 STATISTIC(NumBlocksElim, "Number of blocks eliminated");
107 STATISTIC(NumPHIsElim, "Number of trivial PHIs eliminated");
108 STATISTIC(NumGEPsElim, "Number of GEPs converted to casts");
109 STATISTIC(NumCmpUses, "Number of uses of Cmp expressions replaced with uses of "
110  "sunken Cmps");
111 STATISTIC(NumCastUses, "Number of uses of Cast expressions replaced with uses "
112  "of sunken Casts");
113 STATISTIC(NumMemoryInsts, "Number of memory instructions whose address "
114  "computations were sunk");
115 STATISTIC(NumMemoryInstsPhiCreated,
116  "Number of phis created when address "
117  "computations were sunk to memory instructions");
118 STATISTIC(NumMemoryInstsSelectCreated,
119  "Number of select created when address "
120  "computations were sunk to memory instructions");
121 STATISTIC(NumExtsMoved, "Number of [s|z]ext instructions combined with loads");
122 STATISTIC(NumExtUses, "Number of uses of [s|z]ext instructions optimized");
123 STATISTIC(NumAndsAdded,
124  "Number of and mask instructions added to form ext loads");
125 STATISTIC(NumAndUses, "Number of uses of and mask instructions optimized");
126 STATISTIC(NumRetsDup, "Number of return instructions duplicated");
127 STATISTIC(NumDbgValueMoved, "Number of debug value instructions moved");
128 STATISTIC(NumSelectsExpanded, "Number of selects turned into branches");
129 STATISTIC(NumStoreExtractExposed, "Number of store(extractelement) exposed");
130 
132  "disable-cgp-branch-opts", cl::Hidden, cl::init(false),
133  cl::desc("Disable branch optimizations in CodeGenPrepare"));
134 
135 static cl::opt<bool>
136  DisableGCOpts("disable-cgp-gc-opts", cl::Hidden, cl::init(false),
137  cl::desc("Disable GC optimizations in CodeGenPrepare"));
138 
140  "disable-cgp-select2branch", cl::Hidden, cl::init(false),
141  cl::desc("Disable select to branch conversion."));
142 
144  "addr-sink-using-gep", cl::Hidden, cl::init(true),
145  cl::desc("Address sinking in CGP using GEPs."));
146 
148  "enable-andcmp-sinking", cl::Hidden, cl::init(true),
149  cl::desc("Enable sinkinig and/cmp into branches."));
150 
152  "disable-cgp-store-extract", cl::Hidden, cl::init(false),
153  cl::desc("Disable store(extract) optimizations in CodeGenPrepare"));
154 
156  "stress-cgp-store-extract", cl::Hidden, cl::init(false),
157  cl::desc("Stress test store(extract) optimizations in CodeGenPrepare"));
158 
160  "disable-cgp-ext-ld-promotion", cl::Hidden, cl::init(false),
161  cl::desc("Disable ext(promotable(ld)) -> promoted(ext(ld)) optimization in "
162  "CodeGenPrepare"));
163 
165  "stress-cgp-ext-ld-promotion", cl::Hidden, cl::init(false),
166  cl::desc("Stress test ext(promotable(ld)) -> promoted(ext(ld)) "
167  "optimization in CodeGenPrepare"));
168 
170  "disable-preheader-prot", cl::Hidden, cl::init(false),
171  cl::desc("Disable protection against removing loop preheaders"));
172 
174  "profile-guided-section-prefix", cl::Hidden, cl::init(true), cl::ZeroOrMore,
175  cl::desc("Use profile info to add section prefix for hot/cold functions"));
176 
178  "cgp-freq-ratio-to-skip-merge", cl::Hidden, cl::init(2),
179  cl::desc("Skip merging empty blocks if (frequency of empty block) / "
180  "(frequency of destination block) is greater than this ratio"));
181 
183  "force-split-store", cl::Hidden, cl::init(false),
184  cl::desc("Force store splitting no matter what the target query says."));
185 
186 static cl::opt<bool>
187 EnableTypePromotionMerge("cgp-type-promotion-merge", cl::Hidden,
188  cl::desc("Enable merging of redundant sexts when one is dominating"
189  " the other."), cl::init(true));
190 
192  "disable-complex-addr-modes", cl::Hidden, cl::init(false),
193  cl::desc("Disables combining addressing modes with different parts "
194  "in optimizeMemoryInst."));
195 
196 static cl::opt<bool>
197 AddrSinkNewPhis("addr-sink-new-phis", cl::Hidden, cl::init(false),
198  cl::desc("Allow creation of Phis in Address sinking."));
199 
200 static cl::opt<bool>
201 AddrSinkNewSelects("addr-sink-new-select", cl::Hidden, cl::init(true),
202  cl::desc("Allow creation of selects in Address sinking."));
203 
205  "addr-sink-combine-base-reg", cl::Hidden, cl::init(true),
206  cl::desc("Allow combining of BaseReg field in Address sinking."));
207 
209  "addr-sink-combine-base-gv", cl::Hidden, cl::init(true),
210  cl::desc("Allow combining of BaseGV field in Address sinking."));
211 
213  "addr-sink-combine-base-offs", cl::Hidden, cl::init(true),
214  cl::desc("Allow combining of BaseOffs field in Address sinking."));
215 
217  "addr-sink-combine-scaled-reg", cl::Hidden, cl::init(true),
218  cl::desc("Allow combining of ScaledReg field in Address sinking."));
219 
220 static cl::opt<bool>
221  EnableGEPOffsetSplit("cgp-split-large-offset-gep", cl::Hidden,
222  cl::init(true),
223  cl::desc("Enable splitting large offset of GEP."));
224 
225 namespace {
226 
227 enum ExtType {
228  ZeroExtension, // Zero extension has been seen.
229  SignExtension, // Sign extension has been seen.
230  BothExtension // This extension type is used if we saw sext after
231  // ZeroExtension had been set, or if we saw zext after
232  // SignExtension had been set. It makes the type
233  // information of a promoted instruction invalid.
234 };
235 
236 using SetOfInstrs = SmallPtrSet<Instruction *, 16>;
237 using TypeIsSExt = PointerIntPair<Type *, 2, ExtType>;
238 using InstrToOrigTy = DenseMap<Instruction *, TypeIsSExt>;
239 using SExts = SmallVector<Instruction *, 16>;
240 using ValueToSExts = DenseMap<Value *, SExts>;
241 
242 class TypePromotionTransaction;
243 
244  class CodeGenPrepare : public FunctionPass {
245  const TargetMachine *TM = nullptr;
246  const TargetSubtargetInfo *SubtargetInfo;
247  const TargetLowering *TLI = nullptr;
248  const TargetRegisterInfo *TRI;
249  const TargetTransformInfo *TTI = nullptr;
250  const TargetLibraryInfo *TLInfo;
251  const LoopInfo *LI;
252  std::unique_ptr<BlockFrequencyInfo> BFI;
253  std::unique_ptr<BranchProbabilityInfo> BPI;
254 
255  /// As we scan instructions optimizing them, this is the next instruction
256  /// to optimize. Transforms that can invalidate this should update it.
257  BasicBlock::iterator CurInstIterator;
258 
259  /// Keeps track of non-local addresses that have been sunk into a block.
260  /// This allows us to avoid inserting duplicate code for blocks with
261  /// multiple load/stores of the same address. The usage of WeakTrackingVH
262  /// enables SunkAddrs to be treated as a cache whose entries can be
263  /// invalidated if a sunken address computation has been erased.
265 
266  /// Keeps track of all instructions inserted for the current function.
267  SetOfInstrs InsertedInsts;
268 
269  /// Keeps track of the type of the related instruction before their
270  /// promotion for the current function.
271  InstrToOrigTy PromotedInsts;
272 
273  /// Keep track of instructions removed during promotion.
274  SetOfInstrs RemovedInsts;
275 
276  /// Keep track of sext chains based on their initial value.
277  DenseMap<Value *, Instruction *> SeenChainsForSExt;
278 
279  /// Keep track of GEPs accessing the same data structures such as structs or
280  /// arrays that are candidates to be split later because of their large
281  /// size.
282  MapVector<
285  LargeOffsetGEPMap;
286 
287  /// Keep track of new GEP base after splitting the GEPs having large offset.
288  SmallSet<AssertingVH<Value>, 2> NewGEPBases;
289 
290  /// Map serial numbers to Large offset GEPs.
291  DenseMap<AssertingVH<GetElementPtrInst>, int> LargeOffsetGEPID;
292 
293  /// Keep track of SExt promoted.
294  ValueToSExts ValToSExtendedUses;
295 
296  /// True if optimizing for size.
297  bool OptSize;
298 
299  /// DataLayout for the Function being processed.
300  const DataLayout *DL = nullptr;
301 
302  /// Building the dominator tree can be expensive, so we only build it
303  /// lazily and update it when required.
304  std::unique_ptr<DominatorTree> DT;
305 
306  public:
307  static char ID; // Pass identification, replacement for typeid
308 
309  CodeGenPrepare() : FunctionPass(ID) {
311  }
312 
313  bool runOnFunction(Function &F) override;
314 
315  StringRef getPassName() const override { return "CodeGen Prepare"; }
316 
317  void getAnalysisUsage(AnalysisUsage &AU) const override {
318  // FIXME: When we can selectively preserve passes, preserve the domtree.
323  }
324 
325  private:
326  template <typename F>
327  void resetIteratorIfInvalidatedWhileCalling(BasicBlock *BB, F f) {
328  // Substituting can cause recursive simplifications, which can invalidate
329  // our iterator. Use a WeakTrackingVH to hold onto it in case this
330  // happens.
331  Value *CurValue = &*CurInstIterator;
332  WeakTrackingVH IterHandle(CurValue);
333 
334  f();
335 
336  // If the iterator instruction was recursively deleted, start over at the
337  // start of the block.
338  if (IterHandle != CurValue) {
339  CurInstIterator = BB->begin();
340  SunkAddrs.clear();
341  }
342  }
343 
344  // Get the DominatorTree, building if necessary.
345  DominatorTree &getDT(Function &F) {
346  if (!DT)
347  DT = std::make_unique<DominatorTree>(F);
348  return *DT;
349  }
350 
351  bool eliminateFallThrough(Function &F);
352  bool eliminateMostlyEmptyBlocks(Function &F);
353  BasicBlock *findDestBlockOfMergeableEmptyBlock(BasicBlock *BB);
354  bool canMergeBlocks(const BasicBlock *BB, const BasicBlock *DestBB) const;
355  void eliminateMostlyEmptyBlock(BasicBlock *BB);
356  bool isMergingEmptyBlockProfitable(BasicBlock *BB, BasicBlock *DestBB,
357  bool isPreheader);
358  bool optimizeBlock(BasicBlock &BB, bool &ModifiedDT);
359  bool optimizeInst(Instruction *I, bool &ModifiedDT);
360  bool optimizeMemoryInst(Instruction *MemoryInst, Value *Addr,
361  Type *AccessTy, unsigned AddrSpace);
362  bool optimizeInlineAsmInst(CallInst *CS);
363  bool optimizeCallInst(CallInst *CI, bool &ModifiedDT);
364  bool optimizeExt(Instruction *&I);
365  bool optimizeExtUses(Instruction *I);
366  bool optimizeLoadExt(LoadInst *Load);
367  bool optimizeShiftInst(BinaryOperator *BO);
368  bool optimizeSelectInst(SelectInst *SI);
369  bool optimizeShuffleVectorInst(ShuffleVectorInst *SVI);
370  bool optimizeSwitchInst(SwitchInst *SI);
371  bool optimizeExtractElementInst(Instruction *Inst);
372  bool dupRetToEnableTailCallOpts(BasicBlock *BB, bool &ModifiedDT);
373  bool placeDbgValues(Function &F);
374  bool canFormExtLd(const SmallVectorImpl<Instruction *> &MovedExts,
375  LoadInst *&LI, Instruction *&Inst, bool HasPromoted);
376  bool tryToPromoteExts(TypePromotionTransaction &TPT,
377  const SmallVectorImpl<Instruction *> &Exts,
378  SmallVectorImpl<Instruction *> &ProfitablyMovedExts,
379  unsigned CreatedInstsCost = 0);
380  bool mergeSExts(Function &F);
381  bool splitLargeGEPOffsets();
382  bool performAddressTypePromotion(
383  Instruction *&Inst,
384  bool AllowPromotionWithoutCommonHeader,
385  bool HasPromoted, TypePromotionTransaction &TPT,
386  SmallVectorImpl<Instruction *> &SpeculativelyMovedExts);
387  bool splitBranchCondition(Function &F, bool &ModifiedDT);
388  bool simplifyOffsetableRelocate(Instruction &I);
389 
390  bool tryToSinkFreeOperands(Instruction *I);
391  bool replaceMathCmpWithIntrinsic(BinaryOperator *BO, CmpInst *Cmp,
392  Intrinsic::ID IID);
393  bool optimizeCmp(CmpInst *Cmp, bool &ModifiedDT);
394  bool combineToUSubWithOverflow(CmpInst *Cmp, bool &ModifiedDT);
395  bool combineToUAddWithOverflow(CmpInst *Cmp, bool &ModifiedDT);
396  };
397 
398 } // end anonymous namespace
399 
400 char CodeGenPrepare::ID = 0;
401 
402 INITIALIZE_PASS_BEGIN(CodeGenPrepare, DEBUG_TYPE,
403  "Optimize for code generation", false, false)
406  "Optimize for code generation", false, false)
407 
408 FunctionPass *llvm::createCodeGenPreparePass() { return new CodeGenPrepare(); }
409 
411  if (skipFunction(F))
412  return false;
413 
414  DL = &F.getParent()->getDataLayout();
415 
416  bool EverMadeChange = false;
417  // Clear per function information.
418  InsertedInsts.clear();
419  PromotedInsts.clear();
420 
421  if (auto *TPC = getAnalysisIfAvailable<TargetPassConfig>()) {
422  TM = &TPC->getTM<TargetMachine>();
423  SubtargetInfo = TM->getSubtargetImpl(F);
424  TLI = SubtargetInfo->getTargetLowering();
425  TRI = SubtargetInfo->getRegisterInfo();
426  }
427  TLInfo = &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(F);
428  TTI = &getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
429  LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
430  BPI.reset(new BranchProbabilityInfo(F, *LI));
431  BFI.reset(new BlockFrequencyInfo(F, *BPI, *LI));
432  OptSize = F.hasOptSize();
433 
434  ProfileSummaryInfo *PSI =
435  &getAnalysis<ProfileSummaryInfoWrapperPass>().getPSI();
437  if (PSI->isFunctionHotInCallGraph(&F, *BFI))
438  F.setSectionPrefix(".hot");
439  else if (PSI->isFunctionColdInCallGraph(&F, *BFI))
440  F.setSectionPrefix(".unlikely");
441  }
442 
443  /// This optimization identifies DIV instructions that can be
444  /// profitably bypassed and carried out with a shorter, faster divide.
445  if (!OptSize && !PSI->hasHugeWorkingSetSize() && TLI &&
446  TLI->isSlowDivBypassed()) {
447  const DenseMap<unsigned int, unsigned int> &BypassWidths =
448  TLI->getBypassSlowDivWidths();
449  BasicBlock* BB = &*F.begin();
450  while (BB != nullptr) {
451  // bypassSlowDivision may create new BBs, but we don't want to reapply the
452  // optimization to those blocks.
453  BasicBlock* Next = BB->getNextNode();
454  EverMadeChange |= bypassSlowDivision(BB, BypassWidths);
455  BB = Next;
456  }
457  }
458 
459  // Eliminate blocks that contain only PHI nodes and an
460  // unconditional branch.
461  EverMadeChange |= eliminateMostlyEmptyBlocks(F);
462 
463  bool ModifiedDT = false;
464  if (!DisableBranchOpts)
465  EverMadeChange |= splitBranchCondition(F, ModifiedDT);
466 
467  // Split some critical edges where one of the sources is an indirect branch,
468  // to help generate sane code for PHIs involving such edges.
469  EverMadeChange |= SplitIndirectBrCriticalEdges(F);
470 
471  bool MadeChange = true;
472  while (MadeChange) {
473  MadeChange = false;
474  DT.reset();
475  for (Function::iterator I = F.begin(); I != F.end(); ) {
476  BasicBlock *BB = &*I++;
477  bool ModifiedDTOnIteration = false;
478  MadeChange |= optimizeBlock(*BB, ModifiedDTOnIteration);
479 
480  // Restart BB iteration if the dominator tree of the Function was changed
481  if (ModifiedDTOnIteration)
482  break;
483  }
484  if (EnableTypePromotionMerge && !ValToSExtendedUses.empty())
485  MadeChange |= mergeSExts(F);
486  if (!LargeOffsetGEPMap.empty())
487  MadeChange |= splitLargeGEPOffsets();
488 
489  // Really free removed instructions during promotion.
490  for (Instruction *I : RemovedInsts)
491  I->deleteValue();
492 
493  EverMadeChange |= MadeChange;
494  SeenChainsForSExt.clear();
495  ValToSExtendedUses.clear();
496  RemovedInsts.clear();
497  LargeOffsetGEPMap.clear();
498  LargeOffsetGEPID.clear();
499  }
500 
501  SunkAddrs.clear();
502 
503  if (!DisableBranchOpts) {
504  MadeChange = false;
505  // Use a set vector to get deterministic iteration order. The order the
506  // blocks are removed may affect whether or not PHI nodes in successors
507  // are removed.
509  for (BasicBlock &BB : F) {
510  SmallVector<BasicBlock *, 2> Successors(succ_begin(&BB), succ_end(&BB));
511  MadeChange |= ConstantFoldTerminator(&BB, true);
512  if (!MadeChange) continue;
513 
515  II = Successors.begin(), IE = Successors.end(); II != IE; ++II)
516  if (pred_begin(*II) == pred_end(*II))
517  WorkList.insert(*II);
518  }
519 
520  // Delete the dead blocks and any of their dead successors.
521  MadeChange |= !WorkList.empty();
522  while (!WorkList.empty()) {
523  BasicBlock *BB = WorkList.pop_back_val();
524  SmallVector<BasicBlock*, 2> Successors(succ_begin(BB), succ_end(BB));
525 
526  DeleteDeadBlock(BB);
527 
529  II = Successors.begin(), IE = Successors.end(); II != IE; ++II)
530  if (pred_begin(*II) == pred_end(*II))
531  WorkList.insert(*II);
532  }
533 
534  // Merge pairs of basic blocks with unconditional branches, connected by
535  // a single edge.
536  if (EverMadeChange || MadeChange)
537  MadeChange |= eliminateFallThrough(F);
538 
539  EverMadeChange |= MadeChange;
540  }
541 
542  if (!DisableGCOpts) {
543  SmallVector<Instruction *, 2> Statepoints;
544  for (BasicBlock &BB : F)
545  for (Instruction &I : BB)
546  if (isStatepoint(I))
547  Statepoints.push_back(&I);
548  for (auto &I : Statepoints)
549  EverMadeChange |= simplifyOffsetableRelocate(*I);
550  }
551 
552  // Do this last to clean up use-before-def scenarios introduced by other
553  // preparatory transforms.
554  EverMadeChange |= placeDbgValues(F);
555 
556  return EverMadeChange;
557 }
558 
559 /// Merge basic blocks which are connected by a single edge, where one of the
560 /// basic blocks has a single successor pointing to the other basic block,
561 /// which has a single predecessor.
562 bool CodeGenPrepare::eliminateFallThrough(Function &F) {
563  bool Changed = false;
564  // Scan all of the blocks in the function, except for the entry block.
565  // Use a temporary array to avoid iterator being invalidated when
566  // deleting blocks.
568  for (auto &Block : llvm::make_range(std::next(F.begin()), F.end()))
569  Blocks.push_back(&Block);
570 
571  for (auto &Block : Blocks) {
572  auto *BB = cast_or_null<BasicBlock>(Block);
573  if (!BB)
574  continue;
575  // If the destination block has a single pred, then this is a trivial
576  // edge, just collapse it.
577  BasicBlock *SinglePred = BB->getSinglePredecessor();
578 
579  // Don't merge if BB's address is taken.
580  if (!SinglePred || SinglePred == BB || BB->hasAddressTaken()) continue;
581 
582  BranchInst *Term = dyn_cast<BranchInst>(SinglePred->getTerminator());
583  if (Term && !Term->isConditional()) {
584  Changed = true;
585  LLVM_DEBUG(dbgs() << "To merge:\n" << *BB << "\n\n\n");
586 
587  // Merge BB into SinglePred and delete it.
589  }
590  }
591  return Changed;
592 }
593 
594 /// Find a destination block from BB if BB is mergeable empty block.
595 BasicBlock *CodeGenPrepare::findDestBlockOfMergeableEmptyBlock(BasicBlock *BB) {
596  // If this block doesn't end with an uncond branch, ignore it.
598  if (!BI || !BI->isUnconditional())
599  return nullptr;
600 
601  // If the instruction before the branch (skipping debug info) isn't a phi
602  // node, then other stuff is happening here.
603  BasicBlock::iterator BBI = BI->getIterator();
604  if (BBI != BB->begin()) {
605  --BBI;
606  while (isa<DbgInfoIntrinsic>(BBI)) {
607  if (BBI == BB->begin())
608  break;
609  --BBI;
610  }
611  if (!isa<DbgInfoIntrinsic>(BBI) && !isa<PHINode>(BBI))
612  return nullptr;
613  }
614 
615  // Do not break infinite loops.
616  BasicBlock *DestBB = BI->getSuccessor(0);
617  if (DestBB == BB)
618  return nullptr;
619 
620  if (!canMergeBlocks(BB, DestBB))
621  DestBB = nullptr;
622 
623  return DestBB;
624 }
625 
626 /// Eliminate blocks that contain only PHI nodes, debug info directives, and an
627 /// unconditional branch. Passes before isel (e.g. LSR/loopsimplify) often split
628 /// edges in ways that are non-optimal for isel. Start by eliminating these
629 /// blocks so we can split them the way we want them.
630 bool CodeGenPrepare::eliminateMostlyEmptyBlocks(Function &F) {
632  SmallVector<Loop *, 16> LoopList(LI->begin(), LI->end());
633  while (!LoopList.empty()) {
634  Loop *L = LoopList.pop_back_val();
635  LoopList.insert(LoopList.end(), L->begin(), L->end());
636  if (BasicBlock *Preheader = L->getLoopPreheader())
637  Preheaders.insert(Preheader);
638  }
639 
640  bool MadeChange = false;
641  // Copy blocks into a temporary array to avoid iterator invalidation issues
642  // as we remove them.
643  // Note that this intentionally skips the entry block.
645  for (auto &Block : llvm::make_range(std::next(F.begin()), F.end()))
646  Blocks.push_back(&Block);
647 
648  for (auto &Block : Blocks) {
649  BasicBlock *BB = cast_or_null<BasicBlock>(Block);
650  if (!BB)
651  continue;
652  BasicBlock *DestBB = findDestBlockOfMergeableEmptyBlock(BB);
653  if (!DestBB ||
654  !isMergingEmptyBlockProfitable(BB, DestBB, Preheaders.count(BB)))
655  continue;
656 
657  eliminateMostlyEmptyBlock(BB);
658  MadeChange = true;
659  }
660  return MadeChange;
661 }
662 
663 bool CodeGenPrepare::isMergingEmptyBlockProfitable(BasicBlock *BB,
664  BasicBlock *DestBB,
665  bool isPreheader) {
666  // Do not delete loop preheaders if doing so would create a critical edge.
667  // Loop preheaders can be good locations to spill registers. If the
668  // preheader is deleted and we create a critical edge, registers may be
669  // spilled in the loop body instead.
670  if (!DisablePreheaderProtect && isPreheader &&
671  !(BB->getSinglePredecessor() &&
673  return false;
674 
675  // Skip merging if the block's successor is also a successor to any callbr
676  // that leads to this block.
677  // FIXME: Is this really needed? Is this a correctness issue?
678  for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) {
679  if (auto *CBI = dyn_cast<CallBrInst>((*PI)->getTerminator()))
680  for (unsigned i = 0, e = CBI->getNumSuccessors(); i != e; ++i)
681  if (DestBB == CBI->getSuccessor(i))
682  return false;
683  }
684 
685  // Try to skip merging if the unique predecessor of BB is terminated by a
686  // switch or indirect branch instruction, and BB is used as an incoming block
687  // of PHIs in DestBB. In such case, merging BB and DestBB would cause ISel to
688  // add COPY instructions in the predecessor of BB instead of BB (if it is not
689  // merged). Note that the critical edge created by merging such blocks wont be
690  // split in MachineSink because the jump table is not analyzable. By keeping
691  // such empty block (BB), ISel will place COPY instructions in BB, not in the
692  // predecessor of BB.
693  BasicBlock *Pred = BB->getUniquePredecessor();
694  if (!Pred ||
695  !(isa<SwitchInst>(Pred->getTerminator()) ||
696  isa<IndirectBrInst>(Pred->getTerminator())))
697  return true;
698 
699  if (BB->getTerminator() != BB->getFirstNonPHIOrDbg())
700  return true;
701 
702  // We use a simple cost heuristic which determine skipping merging is
703  // profitable if the cost of skipping merging is less than the cost of
704  // merging : Cost(skipping merging) < Cost(merging BB), where the
705  // Cost(skipping merging) is Freq(BB) * (Cost(Copy) + Cost(Branch)), and
706  // the Cost(merging BB) is Freq(Pred) * Cost(Copy).
707  // Assuming Cost(Copy) == Cost(Branch), we could simplify it to :
708  // Freq(Pred) / Freq(BB) > 2.
709  // Note that if there are multiple empty blocks sharing the same incoming
710  // value for the PHIs in the DestBB, we consider them together. In such
711  // case, Cost(merging BB) will be the sum of their frequencies.
712 
713  if (!isa<PHINode>(DestBB->begin()))
714  return true;
715 
716  SmallPtrSet<BasicBlock *, 16> SameIncomingValueBBs;
717 
718  // Find all other incoming blocks from which incoming values of all PHIs in
719  // DestBB are the same as the ones from BB.
720  for (pred_iterator PI = pred_begin(DestBB), E = pred_end(DestBB); PI != E;
721  ++PI) {
722  BasicBlock *DestBBPred = *PI;
723  if (DestBBPred == BB)
724  continue;
725 
726  if (llvm::all_of(DestBB->phis(), [&](const PHINode &DestPN) {
727  return DestPN.getIncomingValueForBlock(BB) ==
728  DestPN.getIncomingValueForBlock(DestBBPred);
729  }))
730  SameIncomingValueBBs.insert(DestBBPred);
731  }
732 
733  // See if all BB's incoming values are same as the value from Pred. In this
734  // case, no reason to skip merging because COPYs are expected to be place in
735  // Pred already.
736  if (SameIncomingValueBBs.count(Pred))
737  return true;
738 
739  BlockFrequency PredFreq = BFI->getBlockFreq(Pred);
740  BlockFrequency BBFreq = BFI->getBlockFreq(BB);
741 
742  for (auto SameValueBB : SameIncomingValueBBs)
743  if (SameValueBB->getUniquePredecessor() == Pred &&
744  DestBB == findDestBlockOfMergeableEmptyBlock(SameValueBB))
745  BBFreq += BFI->getBlockFreq(SameValueBB);
746 
747  return PredFreq.getFrequency() <=
749 }
750 
751 /// Return true if we can merge BB into DestBB if there is a single
752 /// unconditional branch between them, and BB contains no other non-phi
753 /// instructions.
754 bool CodeGenPrepare::canMergeBlocks(const BasicBlock *BB,
755  const BasicBlock *DestBB) const {
756  // We only want to eliminate blocks whose phi nodes are used by phi nodes in
757  // the successor. If there are more complex condition (e.g. preheaders),
758  // don't mess around with them.
759  for (const PHINode &PN : BB->phis()) {
760  for (const User *U : PN.users()) {
761  const Instruction *UI = cast<Instruction>(U);
762  if (UI->getParent() != DestBB || !isa<PHINode>(UI))
763  return false;
764  // If User is inside DestBB block and it is a PHINode then check
765  // incoming value. If incoming value is not from BB then this is
766  // a complex condition (e.g. preheaders) we want to avoid here.
767  if (UI->getParent() == DestBB) {
768  if (const PHINode *UPN = dyn_cast<PHINode>(UI))
769  for (unsigned I = 0, E = UPN->getNumIncomingValues(); I != E; ++I) {
770  Instruction *Insn = dyn_cast<Instruction>(UPN->getIncomingValue(I));
771  if (Insn && Insn->getParent() == BB &&
772  Insn->getParent() != UPN->getIncomingBlock(I))
773  return false;
774  }
775  }
776  }
777  }
778 
779  // If BB and DestBB contain any common predecessors, then the phi nodes in BB
780  // and DestBB may have conflicting incoming values for the block. If so, we
781  // can't merge the block.
782  const PHINode *DestBBPN = dyn_cast<PHINode>(DestBB->begin());
783  if (!DestBBPN) return true; // no conflict.
784 
785  // Collect the preds of BB.
787  if (const PHINode *BBPN = dyn_cast<PHINode>(BB->begin())) {
788  // It is faster to get preds from a PHI than with pred_iterator.
789  for (unsigned i = 0, e = BBPN->getNumIncomingValues(); i != e; ++i)
790  BBPreds.insert(BBPN->getIncomingBlock(i));
791  } else {
792  BBPreds.insert(pred_begin(BB), pred_end(BB));
793  }
794 
795  // Walk the preds of DestBB.
796  for (unsigned i = 0, e = DestBBPN->getNumIncomingValues(); i != e; ++i) {
797  BasicBlock *Pred = DestBBPN->getIncomingBlock(i);
798  if (BBPreds.count(Pred)) { // Common predecessor?
799  for (const PHINode &PN : DestBB->phis()) {
800  const Value *V1 = PN.getIncomingValueForBlock(Pred);
801  const Value *V2 = PN.getIncomingValueForBlock(BB);
802 
803  // If V2 is a phi node in BB, look up what the mapped value will be.
804  if (const PHINode *V2PN = dyn_cast<PHINode>(V2))
805  if (V2PN->getParent() == BB)
806  V2 = V2PN->getIncomingValueForBlock(Pred);
807 
808  // If there is a conflict, bail out.
809  if (V1 != V2) return false;
810  }
811  }
812  }
813 
814  return true;
815 }
816 
817 /// Eliminate a basic block that has only phi's and an unconditional branch in
818 /// it.
819 void CodeGenPrepare::eliminateMostlyEmptyBlock(BasicBlock *BB) {
820  BranchInst *BI = cast<BranchInst>(BB->getTerminator());
821  BasicBlock *DestBB = BI->getSuccessor(0);
822 
823  LLVM_DEBUG(dbgs() << "MERGING MOSTLY EMPTY BLOCKS - BEFORE:\n"
824  << *BB << *DestBB);
825 
826  // If the destination block has a single pred, then this is a trivial edge,
827  // just collapse it.
828  if (BasicBlock *SinglePred = DestBB->getSinglePredecessor()) {
829  if (SinglePred != DestBB) {
830  assert(SinglePred == BB &&
831  "Single predecessor not the same as predecessor");
832  // Merge DestBB into SinglePred/BB and delete it.
834  // Note: BB(=SinglePred) will not be deleted on this path.
835  // DestBB(=its single successor) is the one that was deleted.
836  LLVM_DEBUG(dbgs() << "AFTER:\n" << *SinglePred << "\n\n\n");
837  return;
838  }
839  }
840 
841  // Otherwise, we have multiple predecessors of BB. Update the PHIs in DestBB
842  // to handle the new incoming edges it is about to have.
843  for (PHINode &PN : DestBB->phis()) {
844  // Remove the incoming value for BB, and remember it.
845  Value *InVal = PN.removeIncomingValue(BB, false);
846 
847  // Two options: either the InVal is a phi node defined in BB or it is some
848  // value that dominates BB.
849  PHINode *InValPhi = dyn_cast<PHINode>(InVal);
850  if (InValPhi && InValPhi->getParent() == BB) {
851  // Add all of the input values of the input PHI as inputs of this phi.
852  for (unsigned i = 0, e = InValPhi->getNumIncomingValues(); i != e; ++i)
853  PN.addIncoming(InValPhi->getIncomingValue(i),
854  InValPhi->getIncomingBlock(i));
855  } else {
856  // Otherwise, add one instance of the dominating value for each edge that
857  // we will be adding.
858  if (PHINode *BBPN = dyn_cast<PHINode>(BB->begin())) {
859  for (unsigned i = 0, e = BBPN->getNumIncomingValues(); i != e; ++i)
860  PN.addIncoming(InVal, BBPN->getIncomingBlock(i));
861  } else {
862  for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI)
863  PN.addIncoming(InVal, *PI);
864  }
865  }
866  }
867 
868  // The PHIs are now updated, change everything that refers to BB to use
869  // DestBB and remove BB.
870  BB->replaceAllUsesWith(DestBB);
871  BB->eraseFromParent();
872  ++NumBlocksElim;
873 
874  LLVM_DEBUG(dbgs() << "AFTER:\n" << *DestBB << "\n\n\n");
875 }
876 
877 // Computes a map of base pointer relocation instructions to corresponding
878 // derived pointer relocation instructions given a vector of all relocate calls
880  const SmallVectorImpl<GCRelocateInst *> &AllRelocateCalls,
882  &RelocateInstMap) {
883  // Collect information in two maps: one primarily for locating the base object
884  // while filling the second map; the second map is the final structure holding
885  // a mapping between Base and corresponding Derived relocate calls
887  for (auto *ThisRelocate : AllRelocateCalls) {
888  auto K = std::make_pair(ThisRelocate->getBasePtrIndex(),
889  ThisRelocate->getDerivedPtrIndex());
890  RelocateIdxMap.insert(std::make_pair(K, ThisRelocate));
891  }
892  for (auto &Item : RelocateIdxMap) {
893  std::pair<unsigned, unsigned> Key = Item.first;
894  if (Key.first == Key.second)
895  // Base relocation: nothing to insert
896  continue;
897 
898  GCRelocateInst *I = Item.second;
899  auto BaseKey = std::make_pair(Key.first, Key.first);
900 
901  // We're iterating over RelocateIdxMap so we cannot modify it.
902  auto MaybeBase = RelocateIdxMap.find(BaseKey);
903  if (MaybeBase == RelocateIdxMap.end())
904  // TODO: We might want to insert a new base object relocate and gep off
905  // that, if there are enough derived object relocates.
906  continue;
907 
908  RelocateInstMap[MaybeBase->second].push_back(I);
909  }
910 }
911 
912 // Accepts a GEP and extracts the operands into a vector provided they're all
913 // small integer constants
915  SmallVectorImpl<Value *> &OffsetV) {
916  for (unsigned i = 1; i < GEP->getNumOperands(); i++) {
917  // Only accept small constant integer operands
918  auto Op = dyn_cast<ConstantInt>(GEP->getOperand(i));
919  if (!Op || Op->getZExtValue() > 20)
920  return false;
921  }
922 
923  for (unsigned i = 1; i < GEP->getNumOperands(); i++)
924  OffsetV.push_back(GEP->getOperand(i));
925  return true;
926 }
927 
928 // Takes a RelocatedBase (base pointer relocation instruction) and Targets to
929 // replace, computes a replacement, and affects it.
930 static bool
932  const SmallVectorImpl<GCRelocateInst *> &Targets) {
933  bool MadeChange = false;
934  // We must ensure the relocation of derived pointer is defined after
935  // relocation of base pointer. If we find a relocation corresponding to base
936  // defined earlier than relocation of base then we move relocation of base
937  // right before found relocation. We consider only relocation in the same
938  // basic block as relocation of base. Relocations from other basic block will
939  // be skipped by optimization and we do not care about them.
940  for (auto R = RelocatedBase->getParent()->getFirstInsertionPt();
941  &*R != RelocatedBase; ++R)
942  if (auto RI = dyn_cast<GCRelocateInst>(R))
943  if (RI->getStatepoint() == RelocatedBase->getStatepoint())
944  if (RI->getBasePtrIndex() == RelocatedBase->getBasePtrIndex()) {
945  RelocatedBase->moveBefore(RI);
946  break;
947  }
948 
949  for (GCRelocateInst *ToReplace : Targets) {
950  assert(ToReplace->getBasePtrIndex() == RelocatedBase->getBasePtrIndex() &&
951  "Not relocating a derived object of the original base object");
952  if (ToReplace->getBasePtrIndex() == ToReplace->getDerivedPtrIndex()) {
953  // A duplicate relocate call. TODO: coalesce duplicates.
954  continue;
955  }
956 
957  if (RelocatedBase->getParent() != ToReplace->getParent()) {
958  // Base and derived relocates are in different basic blocks.
959  // In this case transform is only valid when base dominates derived
960  // relocate. However it would be too expensive to check dominance
961  // for each such relocate, so we skip the whole transformation.
962  continue;
963  }
964 
965  Value *Base = ToReplace->getBasePtr();
966  auto Derived = dyn_cast<GetElementPtrInst>(ToReplace->getDerivedPtr());
967  if (!Derived || Derived->getPointerOperand() != Base)
968  continue;
969 
970  SmallVector<Value *, 2> OffsetV;
971  if (!getGEPSmallConstantIntOffsetV(Derived, OffsetV))
972  continue;
973 
974  // Create a Builder and replace the target callsite with a gep
975  assert(RelocatedBase->getNextNode() &&
976  "Should always have one since it's not a terminator");
977 
978  // Insert after RelocatedBase
979  IRBuilder<> Builder(RelocatedBase->getNextNode());
980  Builder.SetCurrentDebugLocation(ToReplace->getDebugLoc());
981 
982  // If gc_relocate does not match the actual type, cast it to the right type.
983  // In theory, there must be a bitcast after gc_relocate if the type does not
984  // match, and we should reuse it to get the derived pointer. But it could be
985  // cases like this:
986  // bb1:
987  // ...
988  // %g1 = call coldcc i8 addrspace(1)* @llvm.experimental.gc.relocate.p1i8(...)
989  // br label %merge
990  //
991  // bb2:
992  // ...
993  // %g2 = call coldcc i8 addrspace(1)* @llvm.experimental.gc.relocate.p1i8(...)
994  // br label %merge
995  //
996  // merge:
997  // %p1 = phi i8 addrspace(1)* [ %g1, %bb1 ], [ %g2, %bb2 ]
998  // %cast = bitcast i8 addrspace(1)* %p1 in to i32 addrspace(1)*
999  //
1000  // In this case, we can not find the bitcast any more. So we insert a new bitcast
1001  // no matter there is already one or not. In this way, we can handle all cases, and
1002  // the extra bitcast should be optimized away in later passes.
1003  Value *ActualRelocatedBase = RelocatedBase;
1004  if (RelocatedBase->getType() != Base->getType()) {
1005  ActualRelocatedBase =
1006  Builder.CreateBitCast(RelocatedBase, Base->getType());
1007  }
1008  Value *Replacement = Builder.CreateGEP(
1009  Derived->getSourceElementType(), ActualRelocatedBase, makeArrayRef(OffsetV));
1010  Replacement->takeName(ToReplace);
1011  // If the newly generated derived pointer's type does not match the original derived
1012  // pointer's type, cast the new derived pointer to match it. Same reasoning as above.
1013  Value *ActualReplacement = Replacement;
1014  if (Replacement->getType() != ToReplace->getType()) {
1015  ActualReplacement =
1016  Builder.CreateBitCast(Replacement, ToReplace->getType());
1017  }
1018  ToReplace->replaceAllUsesWith(ActualReplacement);
1019  ToReplace->eraseFromParent();
1020 
1021  MadeChange = true;
1022  }
1023  return MadeChange;
1024 }
1025 
1026 // Turns this:
1027 //
1028 // %base = ...
1029 // %ptr = gep %base + 15
1030 // %tok = statepoint (%fun, i32 0, i32 0, i32 0, %base, %ptr)
1031 // %base' = relocate(%tok, i32 4, i32 4)
1032 // %ptr' = relocate(%tok, i32 4, i32 5)
1033 // %val = load %ptr'
1034 //
1035 // into this:
1036 //
1037 // %base = ...
1038 // %ptr = gep %base + 15
1039 // %tok = statepoint (%fun, i32 0, i32 0, i32 0, %base, %ptr)
1040 // %base' = gc.relocate(%tok, i32 4, i32 4)
1041 // %ptr' = gep %base' + 15
1042 // %val = load %ptr'
1043 bool CodeGenPrepare::simplifyOffsetableRelocate(Instruction &I) {
1044  bool MadeChange = false;
1045  SmallVector<GCRelocateInst *, 2> AllRelocateCalls;
1046 
1047  for (auto *U : I.users())
1048  if (GCRelocateInst *Relocate = dyn_cast<GCRelocateInst>(U))
1049  // Collect all the relocate calls associated with a statepoint
1050  AllRelocateCalls.push_back(Relocate);
1051 
1052  // We need atleast one base pointer relocation + one derived pointer
1053  // relocation to mangle
1054  if (AllRelocateCalls.size() < 2)
1055  return false;
1056 
1057  // RelocateInstMap is a mapping from the base relocate instruction to the
1058  // corresponding derived relocate instructions
1060  computeBaseDerivedRelocateMap(AllRelocateCalls, RelocateInstMap);
1061  if (RelocateInstMap.empty())
1062  return false;
1063 
1064  for (auto &Item : RelocateInstMap)
1065  // Item.first is the RelocatedBase to offset against
1066  // Item.second is the vector of Targets to replace
1067  MadeChange = simplifyRelocatesOffABase(Item.first, Item.second);
1068  return MadeChange;
1069 }
1070 
1071 /// Sink the specified cast instruction into its user blocks.
1072 static bool SinkCast(CastInst *CI) {
1073  BasicBlock *DefBB = CI->getParent();
1074 
1075  /// InsertedCasts - Only insert a cast in each block once.
1076  DenseMap<BasicBlock*, CastInst*> InsertedCasts;
1077 
1078  bool MadeChange = false;
1079  for (Value::user_iterator UI = CI->user_begin(), E = CI->user_end();
1080  UI != E; ) {
1081  Use &TheUse = UI.getUse();
1082  Instruction *User = cast<Instruction>(*UI);
1083 
1084  // Figure out which BB this cast is used in. For PHI's this is the
1085  // appropriate predecessor block.
1086  BasicBlock *UserBB = User->getParent();
1087  if (PHINode *PN = dyn_cast<PHINode>(User)) {
1088  UserBB = PN->getIncomingBlock(TheUse);
1089  }
1090 
1091  // Preincrement use iterator so we don't invalidate it.
1092  ++UI;
1093 
1094  // The first insertion point of a block containing an EH pad is after the
1095  // pad. If the pad is the user, we cannot sink the cast past the pad.
1096  if (User->isEHPad())
1097  continue;
1098 
1099  // If the block selected to receive the cast is an EH pad that does not
1100  // allow non-PHI instructions before the terminator, we can't sink the
1101  // cast.
1102  if (UserBB->getTerminator()->isEHPad())
1103  continue;
1104 
1105  // If this user is in the same block as the cast, don't change the cast.
1106  if (UserBB == DefBB) continue;
1107 
1108  // If we have already inserted a cast into this block, use it.
1109  CastInst *&InsertedCast = InsertedCasts[UserBB];
1110 
1111  if (!InsertedCast) {
1112  BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
1113  assert(InsertPt != UserBB->end());
1114  InsertedCast = CastInst::Create(CI->getOpcode(), CI->getOperand(0),
1115  CI->getType(), "", &*InsertPt);
1116  InsertedCast->setDebugLoc(CI->getDebugLoc());
1117  }
1118 
1119  // Replace a use of the cast with a use of the new cast.
1120  TheUse = InsertedCast;
1121  MadeChange = true;
1122  ++NumCastUses;
1123  }
1124 
1125  // If we removed all uses, nuke the cast.
1126  if (CI->use_empty()) {
1127  salvageDebugInfo(*CI);
1128  CI->eraseFromParent();
1129  MadeChange = true;
1130  }
1131 
1132  return MadeChange;
1133 }
1134 
1135 /// If the specified cast instruction is a noop copy (e.g. it's casting from
1136 /// one pointer type to another, i32->i8 on PPC), sink it into user blocks to
1137 /// reduce the number of virtual registers that must be created and coalesced.
1138 ///
1139 /// Return true if any changes are made.
1141  const DataLayout &DL) {
1142  // Sink only "cheap" (or nop) address-space casts. This is a weaker condition
1143  // than sinking only nop casts, but is helpful on some platforms.
1144  if (auto *ASC = dyn_cast<AddrSpaceCastInst>(CI)) {
1145  if (!TLI.isFreeAddrSpaceCast(ASC->getSrcAddressSpace(),
1146  ASC->getDestAddressSpace()))
1147  return false;
1148  }
1149 
1150  // If this is a noop copy,
1151  EVT SrcVT = TLI.getValueType(DL, CI->getOperand(0)->getType());
1152  EVT DstVT = TLI.getValueType(DL, CI->getType());
1153 
1154  // This is an fp<->int conversion?
1155  if (SrcVT.isInteger() != DstVT.isInteger())
1156  return false;
1157 
1158  // If this is an extension, it will be a zero or sign extension, which
1159  // isn't a noop.
1160  if (SrcVT.bitsLT(DstVT)) return false;
1161 
1162  // If these values will be promoted, find out what they will be promoted
1163  // to. This helps us consider truncates on PPC as noop copies when they
1164  // are.
1165  if (TLI.getTypeAction(CI->getContext(), SrcVT) ==
1167  SrcVT = TLI.getTypeToTransformTo(CI->getContext(), SrcVT);
1168  if (TLI.getTypeAction(CI->getContext(), DstVT) ==
1170  DstVT = TLI.getTypeToTransformTo(CI->getContext(), DstVT);
1171 
1172  // If, after promotion, these are the same types, this is a noop copy.
1173  if (SrcVT != DstVT)
1174  return false;
1175 
1176  return SinkCast(CI);
1177 }
1178 
1179 bool CodeGenPrepare::replaceMathCmpWithIntrinsic(BinaryOperator *BO,
1180  CmpInst *Cmp,
1181  Intrinsic::ID IID) {
1182  if (BO->getParent() != Cmp->getParent()) {
1183  // We used to use a dominator tree here to allow multi-block optimization.
1184  // But that was problematic because:
1185  // 1. It could cause a perf regression by hoisting the math op into the
1186  // critical path.
1187  // 2. It could cause a perf regression by creating a value that was live
1188  // across multiple blocks and increasing register pressure.
1189  // 3. Use of a dominator tree could cause large compile-time regression.
1190  // This is because we recompute the DT on every change in the main CGP
1191  // run-loop. The recomputing is probably unnecessary in many cases, so if
1192  // that was fixed, using a DT here would be ok.
1193  return false;
1194  }
1195 
1196  // We allow matching the canonical IR (add X, C) back to (usubo X, -C).
1197  Value *Arg0 = BO->getOperand(0);
1198  Value *Arg1 = BO->getOperand(1);
1199  if (BO->getOpcode() == Instruction::Add &&
1200  IID == Intrinsic::usub_with_overflow) {
1201  assert(isa<Constant>(Arg1) && "Unexpected input for usubo");
1202  Arg1 = ConstantExpr::getNeg(cast<Constant>(Arg1));
1203  }
1204 
1205  // Insert at the first instruction of the pair.
1206  Instruction *InsertPt = nullptr;
1207  for (Instruction &Iter : *Cmp->getParent()) {
1208  if (&Iter == BO || &Iter == Cmp) {
1209  InsertPt = &Iter;
1210  break;
1211  }
1212  }
1213  assert(InsertPt != nullptr && "Parent block did not contain cmp or binop");
1214 
1215  IRBuilder<> Builder(InsertPt);
1216  Value *MathOV = Builder.CreateBinaryIntrinsic(IID, Arg0, Arg1);
1217  Value *Math = Builder.CreateExtractValue(MathOV, 0, "math");
1218  Value *OV = Builder.CreateExtractValue(MathOV, 1, "ov");
1219  BO->replaceAllUsesWith(Math);
1220  Cmp->replaceAllUsesWith(OV);
1221  BO->eraseFromParent();
1222  Cmp->eraseFromParent();
1223  return true;
1224 }
1225 
1226 /// Match special-case patterns that check for unsigned add overflow.
1228  BinaryOperator *&Add) {
1229  // Add = add A, 1; Cmp = icmp eq A,-1 (overflow if A is max val)
1230  // Add = add A,-1; Cmp = icmp ne A, 0 (overflow if A is non-zero)
1231  Value *A = Cmp->getOperand(0), *B = Cmp->getOperand(1);
1232 
1233  // We are not expecting non-canonical/degenerate code. Just bail out.
1234  if (isa<Constant>(A))
1235  return false;
1236 
1237  ICmpInst::Predicate Pred = Cmp->getPredicate();
1238  if (Pred == ICmpInst::ICMP_EQ && match(B, m_AllOnes()))
1239  B = ConstantInt::get(B->getType(), 1);
1240  else if (Pred == ICmpInst::ICMP_NE && match(B, m_ZeroInt()))
1241  B = ConstantInt::get(B->getType(), -1);
1242  else
1243  return false;
1244 
1245  // Check the users of the variable operand of the compare looking for an add
1246  // with the adjusted constant.
1247  for (User *U : A->users()) {
1248  if (match(U, m_Add(m_Specific(A), m_Specific(B)))) {
1249  Add = cast<BinaryOperator>(U);
1250  return true;
1251  }
1252  }
1253  return false;
1254 }
1255 
1256 /// Try to combine the compare into a call to the llvm.uadd.with.overflow
1257 /// intrinsic. Return true if any changes were made.
1258 bool CodeGenPrepare::combineToUAddWithOverflow(CmpInst *Cmp,
1259  bool &ModifiedDT) {
1260  Value *A, *B;
1262  if (!match(Cmp, m_UAddWithOverflow(m_Value(A), m_Value(B), m_BinOp(Add))))
1264  return false;
1265 
1266  if (!TLI->shouldFormOverflowOp(ISD::UADDO,
1267  TLI->getValueType(*DL, Add->getType())))
1268  return false;
1269 
1270  // We don't want to move around uses of condition values this late, so we
1271  // check if it is legal to create the call to the intrinsic in the basic
1272  // block containing the icmp.
1273  if (Add->getParent() != Cmp->getParent() && !Add->hasOneUse())
1274  return false;
1275 
1276  if (!replaceMathCmpWithIntrinsic(Add, Cmp, Intrinsic::uadd_with_overflow))
1277  return false;
1278 
1279  // Reset callers - do not crash by iterating over a dead instruction.
1280  ModifiedDT = true;
1281  return true;
1282 }
1283 
1284 bool CodeGenPrepare::combineToUSubWithOverflow(CmpInst *Cmp,
1285  bool &ModifiedDT) {
1286  // We are not expecting non-canonical/degenerate code. Just bail out.
1287  Value *A = Cmp->getOperand(0), *B = Cmp->getOperand(1);
1288  if (isa<Constant>(A) && isa<Constant>(B))
1289  return false;
1290 
1291  // Convert (A u> B) to (A u< B) to simplify pattern matching.
1292  ICmpInst::Predicate Pred = Cmp->getPredicate();
1293  if (Pred == ICmpInst::ICMP_UGT) {
1294  std::swap(A, B);
1295  Pred = ICmpInst::ICMP_ULT;
1296  }
1297  // Convert special-case: (A == 0) is the same as (A u< 1).
1298  if (Pred == ICmpInst::ICMP_EQ && match(B, m_ZeroInt())) {
1299  B = ConstantInt::get(B->getType(), 1);
1300  Pred = ICmpInst::ICMP_ULT;
1301  }
1302  // Convert special-case: (A != 0) is the same as (0 u< A).
1303  if (Pred == ICmpInst::ICMP_NE && match(B, m_ZeroInt())) {
1304  std::swap(A, B);
1305  Pred = ICmpInst::ICMP_ULT;
1306  }
1307  if (Pred != ICmpInst::ICMP_ULT)
1308  return false;
1309 
1310  // Walk the users of a variable operand of a compare looking for a subtract or
1311  // add with that same operand. Also match the 2nd operand of the compare to
1312  // the add/sub, but that may be a negated constant operand of an add.
1313  Value *CmpVariableOperand = isa<Constant>(A) ? B : A;
1314  BinaryOperator *Sub = nullptr;
1315  for (User *U : CmpVariableOperand->users()) {
1316  // A - B, A u< B --> usubo(A, B)
1317  if (match(U, m_Sub(m_Specific(A), m_Specific(B)))) {
1318  Sub = cast<BinaryOperator>(U);
1319  break;
1320  }
1321 
1322  // A + (-C), A u< C (canonicalized form of (sub A, C))
1323  const APInt *CmpC, *AddC;
1324  if (match(U, m_Add(m_Specific(A), m_APInt(AddC))) &&
1325  match(B, m_APInt(CmpC)) && *AddC == -(*CmpC)) {
1326  Sub = cast<BinaryOperator>(U);
1327  break;
1328  }
1329  }
1330  if (!Sub)
1331  return false;
1332 
1333  if (!TLI->shouldFormOverflowOp(ISD::USUBO,
1334  TLI->getValueType(*DL, Sub->getType())))
1335  return false;
1336 
1337  if (!replaceMathCmpWithIntrinsic(Sub, Cmp, Intrinsic::usub_with_overflow))
1338  return false;
1339 
1340  // Reset callers - do not crash by iterating over a dead instruction.
1341  ModifiedDT = true;
1342  return true;
1343 }
1344 
1345 /// Sink the given CmpInst into user blocks to reduce the number of virtual
1346 /// registers that must be created and coalesced. This is a clear win except on
1347 /// targets with multiple condition code registers (PowerPC), where it might
1348 /// lose; some adjustment may be wanted there.
1349 ///
1350 /// Return true if any changes are made.
1351 static bool sinkCmpExpression(CmpInst *Cmp, const TargetLowering &TLI) {
1353  return false;
1354 
1355  // Avoid sinking soft-FP comparisons, since this can move them into a loop.
1356  if (TLI.useSoftFloat() && isa<FCmpInst>(Cmp))
1357  return false;
1358 
1359  // Only insert a cmp in each block once.
1360  DenseMap<BasicBlock*, CmpInst*> InsertedCmps;
1361 
1362  bool MadeChange = false;
1363  for (Value::user_iterator UI = Cmp->user_begin(), E = Cmp->user_end();
1364  UI != E; ) {
1365  Use &TheUse = UI.getUse();
1366  Instruction *User = cast<Instruction>(*UI);
1367 
1368  // Preincrement use iterator so we don't invalidate it.
1369  ++UI;
1370 
1371  // Don't bother for PHI nodes.
1372  if (isa<PHINode>(User))
1373  continue;
1374 
1375  // Figure out which BB this cmp is used in.
1376  BasicBlock *UserBB = User->getParent();
1377  BasicBlock *DefBB = Cmp->getParent();
1378 
1379  // If this user is in the same block as the cmp, don't change the cmp.
1380  if (UserBB == DefBB) continue;
1381 
1382  // If we have already inserted a cmp into this block, use it.
1383  CmpInst *&InsertedCmp = InsertedCmps[UserBB];
1384 
1385  if (!InsertedCmp) {
1386  BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
1387  assert(InsertPt != UserBB->end());
1388  InsertedCmp =
1389  CmpInst::Create(Cmp->getOpcode(), Cmp->getPredicate(),
1390  Cmp->getOperand(0), Cmp->getOperand(1), "",
1391  &*InsertPt);
1392  // Propagate the debug info.
1393  InsertedCmp->setDebugLoc(Cmp->getDebugLoc());
1394  }
1395 
1396  // Replace a use of the cmp with a use of the new cmp.
1397  TheUse = InsertedCmp;
1398  MadeChange = true;
1399  ++NumCmpUses;
1400  }
1401 
1402  // If we removed all uses, nuke the cmp.
1403  if (Cmp->use_empty()) {
1404  Cmp->eraseFromParent();
1405  MadeChange = true;
1406  }
1407 
1408  return MadeChange;
1409 }
1410 
1411 bool CodeGenPrepare::optimizeCmp(CmpInst *Cmp, bool &ModifiedDT) {
1412  if (sinkCmpExpression(Cmp, *TLI))
1413  return true;
1414 
1415  if (combineToUAddWithOverflow(Cmp, ModifiedDT))
1416  return true;
1417 
1418  if (combineToUSubWithOverflow(Cmp, ModifiedDT))
1419  return true;
1420 
1421  return false;
1422 }
1423 
1424 /// Duplicate and sink the given 'and' instruction into user blocks where it is
1425 /// used in a compare to allow isel to generate better code for targets where
1426 /// this operation can be combined.
1427 ///
1428 /// Return true if any changes are made.
1430  const TargetLowering &TLI,
1431  SetOfInstrs &InsertedInsts) {
1432  // Double-check that we're not trying to optimize an instruction that was
1433  // already optimized by some other part of this pass.
1434  assert(!InsertedInsts.count(AndI) &&
1435  "Attempting to optimize already optimized and instruction");
1436  (void) InsertedInsts;
1437 
1438  // Nothing to do for single use in same basic block.
1439  if (AndI->hasOneUse() &&
1440  AndI->getParent() == cast<Instruction>(*AndI->user_begin())->getParent())
1441  return false;
1442 
1443  // Try to avoid cases where sinking/duplicating is likely to increase register
1444  // pressure.
1445  if (!isa<ConstantInt>(AndI->getOperand(0)) &&
1446  !isa<ConstantInt>(AndI->getOperand(1)) &&
1447  AndI->getOperand(0)->hasOneUse() && AndI->getOperand(1)->hasOneUse())
1448  return false;
1449 
1450  for (auto *U : AndI->users()) {
1451  Instruction *User = cast<Instruction>(U);
1452 
1453  // Only sink 'and' feeding icmp with 0.
1454  if (!isa<ICmpInst>(User))
1455  return false;
1456 
1457  auto *CmpC = dyn_cast<ConstantInt>(User->getOperand(1));
1458  if (!CmpC || !CmpC->isZero())
1459  return false;
1460  }
1461 
1462  if (!TLI.isMaskAndCmp0FoldingBeneficial(*AndI))
1463  return false;
1464 
1465  LLVM_DEBUG(dbgs() << "found 'and' feeding only icmp 0;\n");
1466  LLVM_DEBUG(AndI->getParent()->dump());
1467 
1468  // Push the 'and' into the same block as the icmp 0. There should only be
1469  // one (icmp (and, 0)) in each block, since CSE/GVN should have removed any
1470  // others, so we don't need to keep track of which BBs we insert into.
1471  for (Value::user_iterator UI = AndI->user_begin(), E = AndI->user_end();
1472  UI != E; ) {
1473  Use &TheUse = UI.getUse();
1474  Instruction *User = cast<Instruction>(*UI);
1475 
1476  // Preincrement use iterator so we don't invalidate it.
1477  ++UI;
1478 
1479  LLVM_DEBUG(dbgs() << "sinking 'and' use: " << *User << "\n");
1480 
1481  // Keep the 'and' in the same place if the use is already in the same block.
1482  Instruction *InsertPt =
1483  User->getParent() == AndI->getParent() ? AndI : User;
1484  Instruction *InsertedAnd =
1485  BinaryOperator::Create(Instruction::And, AndI->getOperand(0),
1486  AndI->getOperand(1), "", InsertPt);
1487  // Propagate the debug info.
1488  InsertedAnd->setDebugLoc(AndI->getDebugLoc());
1489 
1490  // Replace a use of the 'and' with a use of the new 'and'.
1491  TheUse = InsertedAnd;
1492  ++NumAndUses;
1493  LLVM_DEBUG(User->getParent()->dump());
1494  }
1495 
1496  // We removed all uses, nuke the and.
1497  AndI->eraseFromParent();
1498  return true;
1499 }
1500 
1501 /// Check if the candidates could be combined with a shift instruction, which
1502 /// includes:
1503 /// 1. Truncate instruction
1504 /// 2. And instruction and the imm is a mask of the low bits:
1505 /// imm & (imm+1) == 0
1507  if (!isa<TruncInst>(User)) {
1508  if (User->getOpcode() != Instruction::And ||
1509  !isa<ConstantInt>(User->getOperand(1)))
1510  return false;
1511 
1512  const APInt &Cimm = cast<ConstantInt>(User->getOperand(1))->getValue();
1513 
1514  if ((Cimm & (Cimm + 1)).getBoolValue())
1515  return false;
1516  }
1517  return true;
1518 }
1519 
1520 /// Sink both shift and truncate instruction to the use of truncate's BB.
1521 static bool
1524  const TargetLowering &TLI, const DataLayout &DL) {
1525  BasicBlock *UserBB = User->getParent();
1526  DenseMap<BasicBlock *, CastInst *> InsertedTruncs;
1527  TruncInst *TruncI = dyn_cast<TruncInst>(User);
1528  bool MadeChange = false;
1529 
1530  for (Value::user_iterator TruncUI = TruncI->user_begin(),
1531  TruncE = TruncI->user_end();
1532  TruncUI != TruncE;) {
1533 
1534  Use &TruncTheUse = TruncUI.getUse();
1535  Instruction *TruncUser = cast<Instruction>(*TruncUI);
1536  // Preincrement use iterator so we don't invalidate it.
1537 
1538  ++TruncUI;
1539 
1540  int ISDOpcode = TLI.InstructionOpcodeToISD(TruncUser->getOpcode());
1541  if (!ISDOpcode)
1542  continue;
1543 
1544  // If the use is actually a legal node, there will not be an
1545  // implicit truncate.
1546  // FIXME: always querying the result type is just an
1547  // approximation; some nodes' legality is determined by the
1548  // operand or other means. There's no good way to find out though.
1549  if (TLI.isOperationLegalOrCustom(
1550  ISDOpcode, TLI.getValueType(DL, TruncUser->getType(), true)))
1551  continue;
1552 
1553  // Don't bother for PHI nodes.
1554  if (isa<PHINode>(TruncUser))
1555  continue;
1556 
1557  BasicBlock *TruncUserBB = TruncUser->getParent();
1558 
1559  if (UserBB == TruncUserBB)
1560  continue;
1561 
1562  BinaryOperator *&InsertedShift = InsertedShifts[TruncUserBB];
1563  CastInst *&InsertedTrunc = InsertedTruncs[TruncUserBB];
1564 
1565  if (!InsertedShift && !InsertedTrunc) {
1566  BasicBlock::iterator InsertPt = TruncUserBB->getFirstInsertionPt();
1567  assert(InsertPt != TruncUserBB->end());
1568  // Sink the shift
1569  if (ShiftI->getOpcode() == Instruction::AShr)
1570  InsertedShift = BinaryOperator::CreateAShr(ShiftI->getOperand(0), CI,
1571  "", &*InsertPt);
1572  else
1573  InsertedShift = BinaryOperator::CreateLShr(ShiftI->getOperand(0), CI,
1574  "", &*InsertPt);
1575  InsertedShift->setDebugLoc(ShiftI->getDebugLoc());
1576 
1577  // Sink the trunc
1578  BasicBlock::iterator TruncInsertPt = TruncUserBB->getFirstInsertionPt();
1579  TruncInsertPt++;
1580  assert(TruncInsertPt != TruncUserBB->end());
1581 
1582  InsertedTrunc = CastInst::Create(TruncI->getOpcode(), InsertedShift,
1583  TruncI->getType(), "", &*TruncInsertPt);
1584  InsertedTrunc->setDebugLoc(TruncI->getDebugLoc());
1585 
1586  MadeChange = true;
1587 
1588  TruncTheUse = InsertedTrunc;
1589  }
1590  }
1591  return MadeChange;
1592 }
1593 
1594 /// Sink the shift *right* instruction into user blocks if the uses could
1595 /// potentially be combined with this shift instruction and generate BitExtract
1596 /// instruction. It will only be applied if the architecture supports BitExtract
1597 /// instruction. Here is an example:
1598 /// BB1:
1599 /// %x.extract.shift = lshr i64 %arg1, 32
1600 /// BB2:
1601 /// %x.extract.trunc = trunc i64 %x.extract.shift to i16
1602 /// ==>
1603 ///
1604 /// BB2:
1605 /// %x.extract.shift.1 = lshr i64 %arg1, 32
1606 /// %x.extract.trunc = trunc i64 %x.extract.shift.1 to i16
1607 ///
1608 /// CodeGen will recognize the pattern in BB2 and generate BitExtract
1609 /// instruction.
1610 /// Return true if any changes are made.
1612  const TargetLowering &TLI,
1613  const DataLayout &DL) {
1614  BasicBlock *DefBB = ShiftI->getParent();
1615 
1616  /// Only insert instructions in each block once.
1618 
1619  bool shiftIsLegal = TLI.isTypeLegal(TLI.getValueType(DL, ShiftI->getType()));
1620 
1621  bool MadeChange = false;
1622  for (Value::user_iterator UI = ShiftI->user_begin(), E = ShiftI->user_end();
1623  UI != E;) {
1624  Use &TheUse = UI.getUse();
1625  Instruction *User = cast<Instruction>(*UI);
1626  // Preincrement use iterator so we don't invalidate it.
1627  ++UI;
1628 
1629  // Don't bother for PHI nodes.
1630  if (isa<PHINode>(User))
1631  continue;
1632 
1633  if (!isExtractBitsCandidateUse(User))
1634  continue;
1635 
1636  BasicBlock *UserBB = User->getParent();
1637 
1638  if (UserBB == DefBB) {
1639  // If the shift and truncate instruction are in the same BB. The use of
1640  // the truncate(TruncUse) may still introduce another truncate if not
1641  // legal. In this case, we would like to sink both shift and truncate
1642  // instruction to the BB of TruncUse.
1643  // for example:
1644  // BB1:
1645  // i64 shift.result = lshr i64 opnd, imm
1646  // trunc.result = trunc shift.result to i16
1647  //
1648  // BB2:
1649  // ----> We will have an implicit truncate here if the architecture does
1650  // not have i16 compare.
1651  // cmp i16 trunc.result, opnd2
1652  //
1653  if (isa<TruncInst>(User) && shiftIsLegal
1654  // If the type of the truncate is legal, no truncate will be
1655  // introduced in other basic blocks.
1656  &&
1657  (!TLI.isTypeLegal(TLI.getValueType(DL, User->getType()))))
1658  MadeChange =
1659  SinkShiftAndTruncate(ShiftI, User, CI, InsertedShifts, TLI, DL);
1660 
1661  continue;
1662  }
1663  // If we have already inserted a shift into this block, use it.
1664  BinaryOperator *&InsertedShift = InsertedShifts[UserBB];
1665 
1666  if (!InsertedShift) {
1667  BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
1668  assert(InsertPt != UserBB->end());
1669 
1670  if (ShiftI->getOpcode() == Instruction::AShr)
1671  InsertedShift = BinaryOperator::CreateAShr(ShiftI->getOperand(0), CI,
1672  "", &*InsertPt);
1673  else
1674  InsertedShift = BinaryOperator::CreateLShr(ShiftI->getOperand(0), CI,
1675  "", &*InsertPt);
1676  InsertedShift->setDebugLoc(ShiftI->getDebugLoc());
1677 
1678  MadeChange = true;
1679  }
1680 
1681  // Replace a use of the shift with a use of the new shift.
1682  TheUse = InsertedShift;
1683  }
1684 
1685  // If we removed all uses, or there are none, nuke the shift.
1686  if (ShiftI->use_empty()) {
1687  salvageDebugInfo(*ShiftI);
1688  ShiftI->eraseFromParent();
1689  MadeChange = true;
1690  }
1691 
1692  return MadeChange;
1693 }
1694 
1695 /// If counting leading or trailing zeros is an expensive operation and a zero
1696 /// input is defined, add a check for zero to avoid calling the intrinsic.
1697 ///
1698 /// We want to transform:
1699 /// %z = call i64 @llvm.cttz.i64(i64 %A, i1 false)
1700 ///
1701 /// into:
1702 /// entry:
1703 /// %cmpz = icmp eq i64 %A, 0
1704 /// br i1 %cmpz, label %cond.end, label %cond.false
1705 /// cond.false:
1706 /// %z = call i64 @llvm.cttz.i64(i64 %A, i1 true)
1707 /// br label %cond.end
1708 /// cond.end:
1709 /// %ctz = phi i64 [ 64, %entry ], [ %z, %cond.false ]
1710 ///
1711 /// If the transform is performed, return true and set ModifiedDT to true.
1712 static bool despeculateCountZeros(IntrinsicInst *CountZeros,
1713  const TargetLowering *TLI,
1714  const DataLayout *DL,
1715  bool &ModifiedDT) {
1716  if (!TLI || !DL)
1717  return false;
1718 
1719  // If a zero input is undefined, it doesn't make sense to despeculate that.
1720  if (match(CountZeros->getOperand(1), m_One()))
1721  return false;
1722 
1723  // If it's cheap to speculate, there's nothing to do.
1724  auto IntrinsicID = CountZeros->getIntrinsicID();
1725  if ((IntrinsicID == Intrinsic::cttz && TLI->isCheapToSpeculateCttz()) ||
1726  (IntrinsicID == Intrinsic::ctlz && TLI->isCheapToSpeculateCtlz()))
1727  return false;
1728 
1729  // Only handle legal scalar cases. Anything else requires too much work.
1730  Type *Ty = CountZeros->getType();
1731  unsigned SizeInBits = Ty->getPrimitiveSizeInBits();
1732  if (Ty->isVectorTy() || SizeInBits > DL->getLargestLegalIntTypeSizeInBits())
1733  return false;
1734 
1735  // The intrinsic will be sunk behind a compare against zero and branch.
1736  BasicBlock *StartBlock = CountZeros->getParent();
1737  BasicBlock *CallBlock = StartBlock->splitBasicBlock(CountZeros, "cond.false");
1738 
1739  // Create another block after the count zero intrinsic. A PHI will be added
1740  // in this block to select the result of the intrinsic or the bit-width
1741  // constant if the input to the intrinsic is zero.
1742  BasicBlock::iterator SplitPt = ++(BasicBlock::iterator(CountZeros));
1743  BasicBlock *EndBlock = CallBlock->splitBasicBlock(SplitPt, "cond.end");
1744 
1745  // Set up a builder to create a compare, conditional branch, and PHI.
1746  IRBuilder<> Builder(CountZeros->getContext());
1747  Builder.SetInsertPoint(StartBlock->getTerminator());
1748  Builder.SetCurrentDebugLocation(CountZeros->getDebugLoc());
1749 
1750  // Replace the unconditional branch that was created by the first split with
1751  // a compare against zero and a conditional branch.
1752  Value *Zero = Constant::getNullValue(Ty);
1753  Value *Cmp = Builder.CreateICmpEQ(CountZeros->getOperand(0), Zero, "cmpz");
1754  Builder.CreateCondBr(Cmp, EndBlock, CallBlock);
1755  StartBlock->getTerminator()->eraseFromParent();
1756 
1757  // Create a PHI in the end block to select either the output of the intrinsic
1758  // or the bit width of the operand.
1759  Builder.SetInsertPoint(&EndBlock->front());
1760  PHINode *PN = Builder.CreatePHI(Ty, 2, "ctz");
1761  CountZeros->replaceAllUsesWith(PN);
1762  Value *BitWidth = Builder.getInt(APInt(SizeInBits, SizeInBits));
1763  PN->addIncoming(BitWidth, StartBlock);
1764  PN->addIncoming(CountZeros, CallBlock);
1765 
1766  // We are explicitly handling the zero case, so we can set the intrinsic's
1767  // undefined zero argument to 'true'. This will also prevent reprocessing the
1768  // intrinsic; we only despeculate when a zero input is defined.
1769  CountZeros->setArgOperand(1, Builder.getTrue());
1770  ModifiedDT = true;
1771  return true;
1772 }
1773 
1774 bool CodeGenPrepare::optimizeCallInst(CallInst *CI, bool &ModifiedDT) {
1775  BasicBlock *BB = CI->getParent();
1776 
1777  // Lower inline assembly if we can.
1778  // If we found an inline asm expession, and if the target knows how to
1779  // lower it to normal LLVM code, do so now.
1780  if (TLI && isa<InlineAsm>(CI->getCalledValue())) {
1781  if (TLI->ExpandInlineAsm(CI)) {
1782  // Avoid invalidating the iterator.
1783  CurInstIterator = BB->begin();
1784  // Avoid processing instructions out of order, which could cause
1785  // reuse before a value is defined.
1786  SunkAddrs.clear();
1787  return true;
1788  }
1789  // Sink address computing for memory operands into the block.
1790  if (optimizeInlineAsmInst(CI))
1791  return true;
1792  }
1793 
1794  // Align the pointer arguments to this call if the target thinks it's a good
1795  // idea
1796  unsigned MinSize, PrefAlign;
1797  if (TLI && TLI->shouldAlignPointerArgs(CI, MinSize, PrefAlign)) {
1798  for (auto &Arg : CI->arg_operands()) {
1799  // We want to align both objects whose address is used directly and
1800  // objects whose address is used in casts and GEPs, though it only makes
1801  // sense for GEPs if the offset is a multiple of the desired alignment and
1802  // if size - offset meets the size threshold.
1803  if (!Arg->getType()->isPointerTy())
1804  continue;
1805  APInt Offset(DL->getIndexSizeInBits(
1806  cast<PointerType>(Arg->getType())->getAddressSpace()),
1807  0);
1808  Value *Val = Arg->stripAndAccumulateInBoundsConstantOffsets(*DL, Offset);
1809  uint64_t Offset2 = Offset.getLimitedValue();
1810  if ((Offset2 & (PrefAlign-1)) != 0)
1811  continue;
1812  AllocaInst *AI;
1813  if ((AI = dyn_cast<AllocaInst>(Val)) && AI->getAlignment() < PrefAlign &&
1814  DL->getTypeAllocSize(AI->getAllocatedType()) >= MinSize + Offset2)
1815  AI->setAlignment(PrefAlign);
1816  // Global variables can only be aligned if they are defined in this
1817  // object (i.e. they are uniquely initialized in this object), and
1818  // over-aligning global variables that have an explicit section is
1819  // forbidden.
1820  GlobalVariable *GV;
1821  if ((GV = dyn_cast<GlobalVariable>(Val)) && GV->canIncreaseAlignment() &&
1822  GV->getPointerAlignment(*DL) < PrefAlign &&
1823  DL->getTypeAllocSize(GV->getValueType()) >=
1824  MinSize + Offset2)
1825  GV->setAlignment(PrefAlign);
1826  }
1827  // If this is a memcpy (or similar) then we may be able to improve the
1828  // alignment
1829  if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(CI)) {
1830  unsigned DestAlign = getKnownAlignment(MI->getDest(), *DL);
1831  if (DestAlign > MI->getDestAlignment())
1832  MI->setDestAlignment(DestAlign);
1833  if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(MI)) {
1834  unsigned SrcAlign = getKnownAlignment(MTI->getSource(), *DL);
1835  if (SrcAlign > MTI->getSourceAlignment())
1836  MTI->setSourceAlignment(SrcAlign);
1837  }
1838  }
1839  }
1840 
1841  // If we have a cold call site, try to sink addressing computation into the
1842  // cold block. This interacts with our handling for loads and stores to
1843  // ensure that we can fold all uses of a potential addressing computation
1844  // into their uses. TODO: generalize this to work over profiling data
1845  if (!OptSize && CI->hasFnAttr(Attribute::Cold))
1846  for (auto &Arg : CI->arg_operands()) {
1847  if (!Arg->getType()->isPointerTy())
1848  continue;
1849  unsigned AS = Arg->getType()->getPointerAddressSpace();
1850  return optimizeMemoryInst(CI, Arg, Arg->getType(), AS);
1851  }
1852 
1854  if (II) {
1855  switch (II->getIntrinsicID()) {
1856  default: break;
1857  case Intrinsic::experimental_widenable_condition: {
1858  // Give up on future widening oppurtunties so that we can fold away dead
1859  // paths and merge blocks before going into block-local instruction
1860  // selection.
1861  if (II->use_empty()) {
1862  II->eraseFromParent();
1863  return true;
1864  }
1865  Constant *RetVal = ConstantInt::getTrue(II->getContext());
1866  resetIteratorIfInvalidatedWhileCalling(BB, [&]() {
1867  replaceAndRecursivelySimplify(CI, RetVal, TLInfo, nullptr);
1868  });
1869  return true;
1870  }
1871  case Intrinsic::objectsize: {
1872  // Lower all uses of llvm.objectsize.*
1873  Value *RetVal =
1874  lowerObjectSizeCall(II, *DL, TLInfo, /*MustSucceed=*/true);
1875 
1876  resetIteratorIfInvalidatedWhileCalling(BB, [&]() {
1877  replaceAndRecursivelySimplify(CI, RetVal, TLInfo, nullptr);
1878  });
1879  return true;
1880  }
1881  case Intrinsic::is_constant: {
1882  // If is_constant hasn't folded away yet, lower it to false now.
1883  Constant *RetVal = ConstantInt::get(II->getType(), 0);
1884  resetIteratorIfInvalidatedWhileCalling(BB, [&]() {
1885  replaceAndRecursivelySimplify(CI, RetVal, TLInfo, nullptr);
1886  });
1887  return true;
1888  }
1889  case Intrinsic::aarch64_stlxr:
1890  case Intrinsic::aarch64_stxr: {
1891  ZExtInst *ExtVal = dyn_cast<ZExtInst>(CI->getArgOperand(0));
1892  if (!ExtVal || !ExtVal->hasOneUse() ||
1893  ExtVal->getParent() == CI->getParent())
1894  return false;
1895  // Sink a zext feeding stlxr/stxr before it, so it can be folded into it.
1896  ExtVal->moveBefore(CI);
1897  // Mark this instruction as "inserted by CGP", so that other
1898  // optimizations don't touch it.
1899  InsertedInsts.insert(ExtVal);
1900  return true;
1901  }
1902 
1903  case Intrinsic::launder_invariant_group:
1904  case Intrinsic::strip_invariant_group: {
1905  Value *ArgVal = II->getArgOperand(0);
1906  auto it = LargeOffsetGEPMap.find(II);
1907  if (it != LargeOffsetGEPMap.end()) {
1908  // Merge entries in LargeOffsetGEPMap to reflect the RAUW.
1909  // Make sure not to have to deal with iterator invalidation
1910  // after possibly adding ArgVal to LargeOffsetGEPMap.
1911  auto GEPs = std::move(it->second);
1912  LargeOffsetGEPMap[ArgVal].append(GEPs.begin(), GEPs.end());
1913  LargeOffsetGEPMap.erase(II);
1914  }
1915 
1916  II->replaceAllUsesWith(ArgVal);
1917  II->eraseFromParent();
1918  return true;
1919  }
1920  case Intrinsic::cttz:
1921  case Intrinsic::ctlz:
1922  // If counting zeros is expensive, try to avoid it.
1923  return despeculateCountZeros(II, TLI, DL, ModifiedDT);
1924  }
1925 
1926  if (TLI) {
1927  SmallVector<Value*, 2> PtrOps;
1928  Type *AccessTy;
1929  if (TLI->getAddrModeArguments(II, PtrOps, AccessTy))
1930  while (!PtrOps.empty()) {
1931  Value *PtrVal = PtrOps.pop_back_val();
1932  unsigned AS = PtrVal->getType()->getPointerAddressSpace();
1933  if (optimizeMemoryInst(II, PtrVal, AccessTy, AS))
1934  return true;
1935  }
1936  }
1937  }
1938 
1939  // From here on out we're working with named functions.
1940  if (!CI->getCalledFunction()) return false;
1941 
1942  // Lower all default uses of _chk calls. This is very similar
1943  // to what InstCombineCalls does, but here we are only lowering calls
1944  // to fortified library functions (e.g. __memcpy_chk) that have the default
1945  // "don't know" as the objectsize. Anything else should be left alone.
1946  FortifiedLibCallSimplifier Simplifier(TLInfo, true);
1947  if (Value *V = Simplifier.optimizeCall(CI)) {
1948  CI->replaceAllUsesWith(V);
1949  CI->eraseFromParent();
1950  return true;
1951  }
1952 
1953  return false;
1954 }
1955 
1956 /// Look for opportunities to duplicate return instructions to the predecessor
1957 /// to enable tail call optimizations. The case it is currently looking for is:
1958 /// @code
1959 /// bb0:
1960 /// %tmp0 = tail call i32 @f0()
1961 /// br label %return
1962 /// bb1:
1963 /// %tmp1 = tail call i32 @f1()
1964 /// br label %return
1965 /// bb2:
1966 /// %tmp2 = tail call i32 @f2()
1967 /// br label %return
1968 /// return:
1969 /// %retval = phi i32 [ %tmp0, %bb0 ], [ %tmp1, %bb1 ], [ %tmp2, %bb2 ]
1970 /// ret i32 %retval
1971 /// @endcode
1972 ///
1973 /// =>
1974 ///
1975 /// @code
1976 /// bb0:
1977 /// %tmp0 = tail call i32 @f0()
1978 /// ret i32 %tmp0
1979 /// bb1:
1980 /// %tmp1 = tail call i32 @f1()
1981 /// ret i32 %tmp1
1982 /// bb2:
1983 /// %tmp2 = tail call i32 @f2()
1984 /// ret i32 %tmp2
1985 /// @endcode
1986 bool CodeGenPrepare::dupRetToEnableTailCallOpts(BasicBlock *BB, bool &ModifiedDT) {
1987  if (!TLI)
1988  return false;
1989 
1990  ReturnInst *RetI = dyn_cast<ReturnInst>(BB->getTerminator());
1991  if (!RetI)
1992  return false;
1993 
1994  PHINode *PN = nullptr;
1995  BitCastInst *BCI = nullptr;
1996  Value *V = RetI->getReturnValue();
1997  if (V) {
1998  BCI = dyn_cast<BitCastInst>(V);
1999  if (BCI)
2000  V = BCI->getOperand(0);
2001 
2002  PN = dyn_cast<PHINode>(V);
2003  if (!PN)
2004  return false;
2005  }
2006 
2007  if (PN && PN->getParent() != BB)
2008  return false;
2009 
2010  // Make sure there are no instructions between the PHI and return, or that the
2011  // return is the first instruction in the block.
2012  if (PN) {
2013  BasicBlock::iterator BI = BB->begin();
2014  // Skip over debug and the bitcast.
2015  do { ++BI; } while (isa<DbgInfoIntrinsic>(BI) || &*BI == BCI);
2016  if (&*BI != RetI)
2017  return false;
2018  } else {
2019  BasicBlock::iterator BI = BB->begin();
2020  while (isa<DbgInfoIntrinsic>(BI)) ++BI;
2021  if (&*BI != RetI)
2022  return false;
2023  }
2024 
2025  /// Only dup the ReturnInst if the CallInst is likely to be emitted as a tail
2026  /// call.
2027  const Function *F = BB->getParent();
2028  SmallVector<BasicBlock*, 4> TailCallBBs;
2029  if (PN) {
2030  for (unsigned I = 0, E = PN->getNumIncomingValues(); I != E; ++I) {
2031  // Look through bitcasts.
2032  Value *IncomingVal = PN->getIncomingValue(I)->stripPointerCasts();
2033  CallInst *CI = dyn_cast<CallInst>(IncomingVal);
2034  BasicBlock *PredBB = PN->getIncomingBlock(I);
2035  // Make sure the phi value is indeed produced by the tail call.
2036  if (CI && CI->hasOneUse() && CI->getParent() == PredBB &&
2037  TLI->mayBeEmittedAsTailCall(CI) &&
2038  attributesPermitTailCall(F, CI, RetI, *TLI))
2039  TailCallBBs.push_back(PredBB);
2040  }
2041  } else {
2042  SmallPtrSet<BasicBlock*, 4> VisitedBBs;
2043  for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB); PI != PE; ++PI) {
2044  if (!VisitedBBs.insert(*PI).second)
2045  continue;
2046 
2047  BasicBlock::InstListType &InstList = (*PI)->getInstList();
2048  BasicBlock::InstListType::reverse_iterator RI = InstList.rbegin();
2049  BasicBlock::InstListType::reverse_iterator RE = InstList.rend();
2050  do { ++RI; } while (RI != RE && isa<DbgInfoIntrinsic>(&*RI));
2051  if (RI == RE)
2052  continue;
2053 
2054  CallInst *CI = dyn_cast<CallInst>(&*RI);
2055  if (CI && CI->use_empty() && TLI->mayBeEmittedAsTailCall(CI) &&
2056  attributesPermitTailCall(F, CI, RetI, *TLI))
2057  TailCallBBs.push_back(*PI);
2058  }
2059  }
2060 
2061  bool Changed = false;
2062  for (auto const &TailCallBB : TailCallBBs) {
2063  // Make sure the call instruction is followed by an unconditional branch to
2064  // the return block.
2065  BranchInst *BI = dyn_cast<BranchInst>(TailCallBB->getTerminator());
2066  if (!BI || !BI->isUnconditional() || BI->getSuccessor(0) != BB)
2067  continue;
2068 
2069  // Duplicate the return into TailCallBB.
2070  (void)FoldReturnIntoUncondBranch(RetI, BB, TailCallBB);
2071  ModifiedDT = Changed = true;
2072  ++NumRetsDup;
2073  }
2074 
2075  // If we eliminated all predecessors of the block, delete the block now.
2076  if (Changed && !BB->hasAddressTaken() && pred_begin(BB) == pred_end(BB))
2077  BB->eraseFromParent();
2078 
2079  return Changed;
2080 }
2081 
2082 //===----------------------------------------------------------------------===//
2083 // Memory Optimization
2084 //===----------------------------------------------------------------------===//
2085 
2086 namespace {
2087 
2088 /// This is an extended version of TargetLowering::AddrMode
2089 /// which holds actual Value*'s for register values.
2090 struct ExtAddrMode : public TargetLowering::AddrMode {
2091  Value *BaseReg = nullptr;
2092  Value *ScaledReg = nullptr;
2093  Value *OriginalValue = nullptr;
2094  bool InBounds = true;
2095 
2096  enum FieldName {
2097  NoField = 0x00,
2098  BaseRegField = 0x01,
2099  BaseGVField = 0x02,
2100  BaseOffsField = 0x04,
2101  ScaledRegField = 0x08,
2102  ScaleField = 0x10,
2103  MultipleFields = 0xff
2104  };
2105 
2106 
2107  ExtAddrMode() = default;
2108 
2109  void print(raw_ostream &OS) const;
2110  void dump() const;
2111 
2112  FieldName compare(const ExtAddrMode &other) {
2113  // First check that the types are the same on each field, as differing types
2114  // is something we can't cope with later on.
2115  if (BaseReg && other.BaseReg &&
2116  BaseReg->getType() != other.BaseReg->getType())
2117  return MultipleFields;
2118  if (BaseGV && other.BaseGV &&
2119  BaseGV->getType() != other.BaseGV->getType())
2120  return MultipleFields;
2121  if (ScaledReg && other.ScaledReg &&
2122  ScaledReg->getType() != other.ScaledReg->getType())
2123  return MultipleFields;
2124 
2125  // Conservatively reject 'inbounds' mismatches.
2126  if (InBounds != other.InBounds)
2127  return MultipleFields;
2128 
2129  // Check each field to see if it differs.
2130  unsigned Result = NoField;
2131  if (BaseReg != other.BaseReg)
2132  Result |= BaseRegField;
2133  if (BaseGV != other.BaseGV)
2134  Result |= BaseGVField;
2135  if (BaseOffs != other.BaseOffs)
2136  Result |= BaseOffsField;
2137  if (ScaledReg != other.ScaledReg)
2138  Result |= ScaledRegField;
2139  // Don't count 0 as being a different scale, because that actually means
2140  // unscaled (which will already be counted by having no ScaledReg).
2141  if (Scale && other.Scale && Scale != other.Scale)
2142  Result |= ScaleField;
2143 
2144  if (countPopulation(Result) > 1)
2145  return MultipleFields;
2146  else
2147  return static_cast<FieldName>(Result);
2148  }
2149 
2150  // An AddrMode is trivial if it involves no calculation i.e. it is just a base
2151  // with no offset.
2152  bool isTrivial() {
2153  // An AddrMode is (BaseGV + BaseReg + BaseOffs + ScaleReg * Scale) so it is
2154  // trivial if at most one of these terms is nonzero, except that BaseGV and
2155  // BaseReg both being zero actually means a null pointer value, which we
2156  // consider to be 'non-zero' here.
2157  return !BaseOffs && !Scale && !(BaseGV && BaseReg);
2158  }
2159 
2160  Value *GetFieldAsValue(FieldName Field, Type *IntPtrTy) {
2161  switch (Field) {
2162  default:
2163  return nullptr;
2164  case BaseRegField:
2165  return BaseReg;
2166  case BaseGVField:
2167  return BaseGV;
2168  case ScaledRegField:
2169  return ScaledReg;
2170  case BaseOffsField:
2171  return ConstantInt::get(IntPtrTy, BaseOffs);
2172  }
2173  }
2174 
2175  void SetCombinedField(FieldName Field, Value *V,
2176  const SmallVectorImpl<ExtAddrMode> &AddrModes) {
2177  switch (Field) {
2178  default:
2179  llvm_unreachable("Unhandled fields are expected to be rejected earlier");
2180  break;
2181  case ExtAddrMode::BaseRegField:
2182  BaseReg = V;
2183  break;
2184  case ExtAddrMode::BaseGVField:
2185  // A combined BaseGV is an Instruction, not a GlobalValue, so it goes
2186  // in the BaseReg field.
2187  assert(BaseReg == nullptr);
2188  BaseReg = V;
2189  BaseGV = nullptr;
2190  break;
2191  case ExtAddrMode::ScaledRegField:
2192  ScaledReg = V;
2193  // If we have a mix of scaled and unscaled addrmodes then we want scale
2194  // to be the scale and not zero.
2195  if (!Scale)
2196  for (const ExtAddrMode &AM : AddrModes)
2197  if (AM.Scale) {
2198  Scale = AM.Scale;
2199  break;
2200  }
2201  break;
2202  case ExtAddrMode::BaseOffsField:
2203  // The offset is no longer a constant, so it goes in ScaledReg with a
2204  // scale of 1.
2205  assert(ScaledReg == nullptr);
2206  ScaledReg = V;
2207  Scale = 1;
2208  BaseOffs = 0;
2209  break;
2210  }
2211  }
2212 };
2213 
2214 } // end anonymous namespace
2215 
2216 #ifndef NDEBUG
2217 static inline raw_ostream &operator<<(raw_ostream &OS, const ExtAddrMode &AM) {
2218  AM.print(OS);
2219  return OS;
2220 }
2221 #endif
2222 
2223 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
2224 void ExtAddrMode::print(raw_ostream &OS) const {
2225  bool NeedPlus = false;
2226  OS << "[";
2227  if (InBounds)
2228  OS << "inbounds ";
2229  if (BaseGV) {
2230  OS << (NeedPlus ? " + " : "")
2231  << "GV:";
2232  BaseGV->printAsOperand(OS, /*PrintType=*/false);
2233  NeedPlus = true;
2234  }
2235 
2236  if (BaseOffs) {
2237  OS << (NeedPlus ? " + " : "")
2238  << BaseOffs;
2239  NeedPlus = true;
2240  }
2241 
2242  if (BaseReg) {
2243  OS << (NeedPlus ? " + " : "")
2244  << "Base:";
2245  BaseReg->printAsOperand(OS, /*PrintType=*/false);
2246  NeedPlus = true;
2247  }
2248  if (Scale) {
2249  OS << (NeedPlus ? " + " : "")
2250  << Scale << "*";
2251  ScaledReg->printAsOperand(OS, /*PrintType=*/false);
2252  }
2253 
2254  OS << ']';
2255 }
2256 
2257 LLVM_DUMP_METHOD void ExtAddrMode::dump() const {
2258  print(dbgs());
2259  dbgs() << '\n';
2260 }
2261 #endif
2262 
2263 namespace {
2264 
2265 /// This class provides transaction based operation on the IR.
2266 /// Every change made through this class is recorded in the internal state and
2267 /// can be undone (rollback) until commit is called.
2268 class TypePromotionTransaction {
2269  /// This represents the common interface of the individual transaction.
2270  /// Each class implements the logic for doing one specific modification on
2271  /// the IR via the TypePromotionTransaction.
2272  class TypePromotionAction {
2273  protected:
2274  /// The Instruction modified.
2275  Instruction *Inst;
2276 
2277  public:
2278  /// Constructor of the action.
2279  /// The constructor performs the related action on the IR.
2280  TypePromotionAction(Instruction *Inst) : Inst(Inst) {}
2281 
2282  virtual ~TypePromotionAction() = default;
2283 
2284  /// Undo the modification done by this action.
2285  /// When this method is called, the IR must be in the same state as it was
2286  /// before this action was applied.
2287  /// \pre Undoing the action works if and only if the IR is in the exact same
2288  /// state as it was directly after this action was applied.
2289  virtual void undo() = 0;
2290 
2291  /// Advocate every change made by this action.
2292  /// When the results on the IR of the action are to be kept, it is important
2293  /// to call this function, otherwise hidden information may be kept forever.
2294  virtual void commit() {
2295  // Nothing to be done, this action is not doing anything.
2296  }
2297  };
2298 
2299  /// Utility to remember the position of an instruction.
2300  class InsertionHandler {
2301  /// Position of an instruction.
2302  /// Either an instruction:
2303  /// - Is the first in a basic block: BB is used.
2304  /// - Has a previous instruction: PrevInst is used.
2305  union {
2306  Instruction *PrevInst;
2307  BasicBlock *BB;
2308  } Point;
2309 
2310  /// Remember whether or not the instruction had a previous instruction.
2311  bool HasPrevInstruction;
2312 
2313  public:
2314  /// Record the position of \p Inst.
2315  InsertionHandler(Instruction *Inst) {
2316  BasicBlock::iterator It = Inst->getIterator();
2317  HasPrevInstruction = (It != (Inst->getParent()->begin()));
2318  if (HasPrevInstruction)
2319  Point.PrevInst = &*--It;
2320  else
2321  Point.BB = Inst->getParent();
2322  }
2323 
2324  /// Insert \p Inst at the recorded position.
2325  void insert(Instruction *Inst) {
2326  if (HasPrevInstruction) {
2327  if (Inst->getParent())
2328  Inst->removeFromParent();
2329  Inst->insertAfter(Point.PrevInst);
2330  } else {
2331  Instruction *Position = &*Point.BB->getFirstInsertionPt();
2332  if (Inst->getParent())
2333  Inst->moveBefore(Position);
2334  else
2335  Inst->insertBefore(Position);
2336  }
2337  }
2338  };
2339 
2340  /// Move an instruction before another.
2341  class InstructionMoveBefore : public TypePromotionAction {
2342  /// Original position of the instruction.
2343  InsertionHandler Position;
2344 
2345  public:
2346  /// Move \p Inst before \p Before.
2347  InstructionMoveBefore(Instruction *Inst, Instruction *Before)
2348  : TypePromotionAction(Inst), Position(Inst) {
2349  LLVM_DEBUG(dbgs() << "Do: move: " << *Inst << "\nbefore: " << *Before
2350  << "\n");
2351  Inst->moveBefore(Before);
2352  }
2353 
2354  /// Move the instruction back to its original position.
2355  void undo() override {
2356  LLVM_DEBUG(dbgs() << "Undo: moveBefore: " << *Inst << "\n");
2357  Position.insert(Inst);
2358  }
2359  };
2360 
2361  /// Set the operand of an instruction with a new value.
2362  class OperandSetter : public TypePromotionAction {
2363  /// Original operand of the instruction.
2364  Value *Origin;
2365 
2366  /// Index of the modified instruction.
2367  unsigned Idx;
2368 
2369  public:
2370  /// Set \p Idx operand of \p Inst with \p NewVal.
2371  OperandSetter(Instruction *Inst, unsigned Idx, Value *NewVal)
2372  : TypePromotionAction(Inst), Idx(Idx) {
2373  LLVM_DEBUG(dbgs() << "Do: setOperand: " << Idx << "\n"
2374  << "for:" << *Inst << "\n"
2375  << "with:" << *NewVal << "\n");
2376  Origin = Inst->getOperand(Idx);
2377  Inst->setOperand(Idx, NewVal);
2378  }
2379 
2380  /// Restore the original value of the instruction.
2381  void undo() override {
2382  LLVM_DEBUG(dbgs() << "Undo: setOperand:" << Idx << "\n"
2383  << "for: " << *Inst << "\n"
2384  << "with: " << *Origin << "\n");
2385  Inst->setOperand(Idx, Origin);
2386  }
2387  };
2388 
2389  /// Hide the operands of an instruction.
2390  /// Do as if this instruction was not using any of its operands.
2391  class OperandsHider : public TypePromotionAction {
2392  /// The list of original operands.
2393  SmallVector<Value *, 4> OriginalValues;
2394 
2395  public:
2396  /// Remove \p Inst from the uses of the operands of \p Inst.
2397  OperandsHider(Instruction *Inst) : TypePromotionAction(Inst) {
2398  LLVM_DEBUG(dbgs() << "Do: OperandsHider: " << *Inst << "\n");
2399  unsigned NumOpnds = Inst->getNumOperands();
2400  OriginalValues.reserve(NumOpnds);
2401  for (unsigned It = 0; It < NumOpnds; ++It) {
2402  // Save the current operand.
2403  Value *Val = Inst->getOperand(It);
2404  OriginalValues.push_back(Val);
2405  // Set a dummy one.
2406  // We could use OperandSetter here, but that would imply an overhead
2407  // that we are not willing to pay.
2408  Inst->setOperand(It, UndefValue::get(Val->getType()));
2409  }
2410  }
2411 
2412  /// Restore the original list of uses.
2413  void undo() override {
2414  LLVM_DEBUG(dbgs() << "Undo: OperandsHider: " << *Inst << "\n");
2415  for (unsigned It = 0, EndIt = OriginalValues.size(); It != EndIt; ++It)
2416  Inst->setOperand(It, OriginalValues[It]);
2417  }
2418  };
2419 
2420  /// Build a truncate instruction.
2421  class TruncBuilder : public TypePromotionAction {
2422  Value *Val;
2423 
2424  public:
2425  /// Build a truncate instruction of \p Opnd producing a \p Ty
2426  /// result.
2427  /// trunc Opnd to Ty.
2428  TruncBuilder(Instruction *Opnd, Type *Ty) : TypePromotionAction(Opnd) {
2429  IRBuilder<> Builder(Opnd);
2430  Val = Builder.CreateTrunc(Opnd, Ty, "promoted");
2431  LLVM_DEBUG(dbgs() << "Do: TruncBuilder: " << *Val << "\n");
2432  }
2433 
2434  /// Get the built value.
2435  Value *getBuiltValue() { return Val; }
2436 
2437  /// Remove the built instruction.
2438  void undo() override {
2439  LLVM_DEBUG(dbgs() << "Undo: TruncBuilder: " << *Val << "\n");
2440  if (Instruction *IVal = dyn_cast<Instruction>(Val))
2441  IVal->eraseFromParent();
2442  }
2443  };
2444 
2445  /// Build a sign extension instruction.
2446  class SExtBuilder : public TypePromotionAction {
2447  Value *Val;
2448 
2449  public:
2450  /// Build a sign extension instruction of \p Opnd producing a \p Ty
2451  /// result.
2452  /// sext Opnd to Ty.
2453  SExtBuilder(Instruction *InsertPt, Value *Opnd, Type *Ty)
2454  : TypePromotionAction(InsertPt) {
2455  IRBuilder<> Builder(InsertPt);
2456  Val = Builder.CreateSExt(Opnd, Ty, "promoted");
2457  LLVM_DEBUG(dbgs() << "Do: SExtBuilder: " << *Val << "\n");
2458  }
2459 
2460  /// Get the built value.
2461  Value *getBuiltValue() { return Val; }
2462 
2463  /// Remove the built instruction.
2464  void undo() override {
2465  LLVM_DEBUG(dbgs() << "Undo: SExtBuilder: " << *Val << "\n");
2466  if (Instruction *IVal = dyn_cast<Instruction>(Val))
2467  IVal->eraseFromParent();
2468  }
2469  };
2470 
2471  /// Build a zero extension instruction.
2472  class ZExtBuilder : public TypePromotionAction {
2473  Value *Val;
2474 
2475  public:
2476  /// Build a zero extension instruction of \p Opnd producing a \p Ty
2477  /// result.
2478  /// zext Opnd to Ty.
2479  ZExtBuilder(Instruction *InsertPt, Value *Opnd, Type *Ty)
2480  : TypePromotionAction(InsertPt) {
2481  IRBuilder<> Builder(InsertPt);
2482  Val = Builder.CreateZExt(Opnd, Ty, "promoted");
2483  LLVM_DEBUG(dbgs() << "Do: ZExtBuilder: " << *Val << "\n");
2484  }
2485 
2486  /// Get the built value.
2487  Value *getBuiltValue() { return Val; }
2488 
2489  /// Remove the built instruction.
2490  void undo() override {
2491  LLVM_DEBUG(dbgs() << "Undo: ZExtBuilder: " << *Val << "\n");
2492  if (Instruction *IVal = dyn_cast<Instruction>(Val))
2493  IVal->eraseFromParent();
2494  }
2495  };
2496 
2497  /// Mutate an instruction to another type.
2498  class TypeMutator : public TypePromotionAction {
2499  /// Record the original type.
2500  Type *OrigTy;
2501 
2502  public:
2503  /// Mutate the type of \p Inst into \p NewTy.
2504  TypeMutator(Instruction *Inst, Type *NewTy)
2505  : TypePromotionAction(Inst), OrigTy(Inst->getType()) {
2506  LLVM_DEBUG(dbgs() << "Do: MutateType: " << *Inst << " with " << *NewTy
2507  << "\n");
2508  Inst->mutateType(NewTy);
2509  }
2510 
2511  /// Mutate the instruction back to its original type.
2512  void undo() override {
2513  LLVM_DEBUG(dbgs() << "Undo: MutateType: " << *Inst << " with " << *OrigTy
2514  << "\n");
2515  Inst->mutateType(OrigTy);
2516  }
2517  };
2518 
2519  /// Replace the uses of an instruction by another instruction.
2520  class UsesReplacer : public TypePromotionAction {
2521  /// Helper structure to keep track of the replaced uses.
2522  struct InstructionAndIdx {
2523  /// The instruction using the instruction.
2524  Instruction *Inst;
2525 
2526  /// The index where this instruction is used for Inst.
2527  unsigned Idx;
2528 
2529  InstructionAndIdx(Instruction *Inst, unsigned Idx)
2530  : Inst(Inst), Idx(Idx) {}
2531  };
2532 
2533  /// Keep track of the original uses (pair Instruction, Index).
2534  SmallVector<InstructionAndIdx, 4> OriginalUses;
2535  /// Keep track of the debug users.
2537 
2538  using use_iterator = SmallVectorImpl<InstructionAndIdx>::iterator;
2539 
2540  public:
2541  /// Replace all the use of \p Inst by \p New.
2542  UsesReplacer(Instruction *Inst, Value *New) : TypePromotionAction(Inst) {
2543  LLVM_DEBUG(dbgs() << "Do: UsersReplacer: " << *Inst << " with " << *New
2544  << "\n");
2545  // Record the original uses.
2546  for (Use &U : Inst->uses()) {
2547  Instruction *UserI = cast<Instruction>(U.getUser());
2548  OriginalUses.push_back(InstructionAndIdx(UserI, U.getOperandNo()));
2549  }
2550  // Record the debug uses separately. They are not in the instruction's
2551  // use list, but they are replaced by RAUW.
2552  findDbgValues(DbgValues, Inst);
2553 
2554  // Now, we can replace the uses.
2555  Inst->replaceAllUsesWith(New);
2556  }
2557 
2558  /// Reassign the original uses of Inst to Inst.
2559  void undo() override {
2560  LLVM_DEBUG(dbgs() << "Undo: UsersReplacer: " << *Inst << "\n");
2561  for (use_iterator UseIt = OriginalUses.begin(),
2562  EndIt = OriginalUses.end();
2563  UseIt != EndIt; ++UseIt) {
2564  UseIt->Inst->setOperand(UseIt->Idx, Inst);
2565  }
2566  // RAUW has replaced all original uses with references to the new value,
2567  // including the debug uses. Since we are undoing the replacements,
2568  // the original debug uses must also be reinstated to maintain the
2569  // correctness and utility of debug value instructions.
2570  for (auto *DVI: DbgValues) {
2571  LLVMContext &Ctx = Inst->getType()->getContext();
2572  auto *MV = MetadataAsValue::get(Ctx, ValueAsMetadata::get(Inst));
2573  DVI->setOperand(0, MV);
2574  }
2575  }
2576  };
2577 
2578  /// Remove an instruction from the IR.
2579  class InstructionRemover : public TypePromotionAction {
2580  /// Original position of the instruction.
2581  InsertionHandler Inserter;
2582 
2583  /// Helper structure to hide all the link to the instruction. In other
2584  /// words, this helps to do as if the instruction was removed.
2585  OperandsHider Hider;
2586 
2587  /// Keep track of the uses replaced, if any.
2588  UsesReplacer *Replacer = nullptr;
2589 
2590  /// Keep track of instructions removed.
2591  SetOfInstrs &RemovedInsts;
2592 
2593  public:
2594  /// Remove all reference of \p Inst and optionally replace all its
2595  /// uses with New.
2596  /// \p RemovedInsts Keep track of the instructions removed by this Action.
2597  /// \pre If !Inst->use_empty(), then New != nullptr
2598  InstructionRemover(Instruction *Inst, SetOfInstrs &RemovedInsts,
2599  Value *New = nullptr)
2600  : TypePromotionAction(Inst), Inserter(Inst), Hider(Inst),
2601  RemovedInsts(RemovedInsts) {
2602  if (New)
2603  Replacer = new UsesReplacer(Inst, New);
2604  LLVM_DEBUG(dbgs() << "Do: InstructionRemover: " << *Inst << "\n");
2605  RemovedInsts.insert(Inst);
2606  /// The instructions removed here will be freed after completing
2607  /// optimizeBlock() for all blocks as we need to keep track of the
2608  /// removed instructions during promotion.
2609  Inst->removeFromParent();
2610  }
2611 
2612  ~InstructionRemover() override { delete Replacer; }
2613 
2614  /// Resurrect the instruction and reassign it to the proper uses if
2615  /// new value was provided when build this action.
2616  void undo() override {
2617  LLVM_DEBUG(dbgs() << "Undo: InstructionRemover: " << *Inst << "\n");
2618  Inserter.insert(Inst);
2619  if (Replacer)
2620  Replacer->undo();
2621  Hider.undo();
2622  RemovedInsts.erase(Inst);
2623  }
2624  };
2625 
2626 public:
2627  /// Restoration point.
2628  /// The restoration point is a pointer to an action instead of an iterator
2629  /// because the iterator may be invalidated but not the pointer.
2630  using ConstRestorationPt = const TypePromotionAction *;
2631 
2632  TypePromotionTransaction(SetOfInstrs &RemovedInsts)
2633  : RemovedInsts(RemovedInsts) {}
2634 
2635  /// Advocate every changes made in that transaction.
2636  void commit();
2637 
2638  /// Undo all the changes made after the given point.
2639  void rollback(ConstRestorationPt Point);
2640 
2641  /// Get the current restoration point.
2642  ConstRestorationPt getRestorationPoint() const;
2643 
2644  /// \name API for IR modification with state keeping to support rollback.
2645  /// @{
2646  /// Same as Instruction::setOperand.
2647  void setOperand(Instruction *Inst, unsigned Idx, Value *NewVal);
2648 
2649  /// Same as Instruction::eraseFromParent.
2650  void eraseInstruction(Instruction *Inst, Value *NewVal = nullptr);
2651 
2652  /// Same as Value::replaceAllUsesWith.
2653  void replaceAllUsesWith(Instruction *Inst, Value *New);
2654 
2655  /// Same as Value::mutateType.
2656  void mutateType(Instruction *Inst, Type *NewTy);
2657 
2658  /// Same as IRBuilder::createTrunc.
2659  Value *createTrunc(Instruction *Opnd, Type *Ty);
2660 
2661  /// Same as IRBuilder::createSExt.
2662  Value *createSExt(Instruction *Inst, Value *Opnd, Type *Ty);
2663 
2664  /// Same as IRBuilder::createZExt.
2665  Value *createZExt(Instruction *Inst, Value *Opnd, Type *Ty);
2666 
2667  /// Same as Instruction::moveBefore.
2668  void moveBefore(Instruction *Inst, Instruction *Before);
2669  /// @}
2670 
2671 private:
2672  /// The ordered list of actions made so far.
2674 
2675  using CommitPt = SmallVectorImpl<std::unique_ptr<TypePromotionAction>>::iterator;
2676 
2677  SetOfInstrs &RemovedInsts;
2678 };
2679 
2680 } // end anonymous namespace
2681 
2682 void TypePromotionTransaction::setOperand(Instruction *Inst, unsigned Idx,
2683  Value *NewVal) {
2684  Actions.push_back(std::make_unique<TypePromotionTransaction::OperandSetter>(
2685  Inst, Idx, NewVal));
2686 }
2687 
2689  Value *NewVal) {
2690  Actions.push_back(
2691  std::make_unique<TypePromotionTransaction::InstructionRemover>(
2692  Inst, RemovedInsts, NewVal));
2693 }
2694 
2695 void TypePromotionTransaction::replaceAllUsesWith(Instruction *Inst,
2696  Value *New) {
2697  Actions.push_back(
2698  std::make_unique<TypePromotionTransaction::UsesReplacer>(Inst, New));
2699 }
2700 
2701 void TypePromotionTransaction::mutateType(Instruction *Inst, Type *NewTy) {
2702  Actions.push_back(
2703  std::make_unique<TypePromotionTransaction::TypeMutator>(Inst, NewTy));
2704 }
2705 
2706 Value *TypePromotionTransaction::createTrunc(Instruction *Opnd,
2707  Type *Ty) {
2708  std::unique_ptr<TruncBuilder> Ptr(new TruncBuilder(Opnd, Ty));
2709  Value *Val = Ptr->getBuiltValue();
2710  Actions.push_back(std::move(Ptr));
2711  return Val;
2712 }
2713 
2714 Value *TypePromotionTransaction::createSExt(Instruction *Inst,
2715  Value *Opnd, Type *Ty) {
2716  std::unique_ptr<SExtBuilder> Ptr(new SExtBuilder(Inst, Opnd, Ty));
2717  Value *Val = Ptr->getBuiltValue();
2718  Actions.push_back(std::move(Ptr));
2719  return Val;
2720 }
2721 
2722 Value *TypePromotionTransaction::createZExt(Instruction *Inst,
2723  Value *Opnd, Type *Ty) {
2724  std::unique_ptr<ZExtBuilder> Ptr(new ZExtBuilder(Inst, Opnd, Ty));
2725  Value *Val = Ptr->getBuiltValue();
2726  Actions.push_back(std::move(Ptr));
2727  return Val;
2728 }
2729 
2730 void TypePromotionTransaction::moveBefore(Instruction *Inst,
2731  Instruction *Before) {
2732  Actions.push_back(
2733  std::make_unique<TypePromotionTransaction::InstructionMoveBefore>(
2734  Inst, Before));
2735 }
2736 
2737 TypePromotionTransaction::ConstRestorationPt
2738 TypePromotionTransaction::getRestorationPoint() const {
2739  return !Actions.empty() ? Actions.back().get() : nullptr;
2740 }
2741 
2742 void TypePromotionTransaction::commit() {
2743  for (CommitPt It = Actions.begin(), EndIt = Actions.end(); It != EndIt;
2744  ++It)
2745  (*It)->commit();
2746  Actions.clear();
2747 }
2748 
2749 void TypePromotionTransaction::rollback(
2750  TypePromotionTransaction::ConstRestorationPt Point) {
2751  while (!Actions.empty() && Point != Actions.back().get()) {
2752  std::unique_ptr<TypePromotionAction> Curr = Actions.pop_back_val();
2753  Curr->undo();
2754  }
2755 }
2756 
2757 namespace {
2758 
2759 /// A helper class for matching addressing modes.
2760 ///
2761 /// This encapsulates the logic for matching the target-legal addressing modes.
2762 class AddressingModeMatcher {
2763  SmallVectorImpl<Instruction*> &AddrModeInsts;
2764  const TargetLowering &TLI;
2765  const TargetRegisterInfo &TRI;
2766  const DataLayout &DL;
2767 
2768  /// AccessTy/MemoryInst - This is the type for the access (e.g. double) and
2769  /// the memory instruction that we're computing this address for.
2770  Type *AccessTy;
2771  unsigned AddrSpace;
2772  Instruction *MemoryInst;
2773 
2774  /// This is the addressing mode that we're building up. This is
2775  /// part of the return value of this addressing mode matching stuff.
2776  ExtAddrMode &AddrMode;
2777 
2778  /// The instructions inserted by other CodeGenPrepare optimizations.
2779  const SetOfInstrs &InsertedInsts;
2780 
2781  /// A map from the instructions to their type before promotion.
2782  InstrToOrigTy &PromotedInsts;
2783 
2784  /// The ongoing transaction where every action should be registered.
2785  TypePromotionTransaction &TPT;
2786 
2787  // A GEP which has too large offset to be folded into the addressing mode.
2788  std::pair<AssertingVH<GetElementPtrInst>, int64_t> &LargeOffsetGEP;
2789 
2790  /// This is set to true when we should not do profitability checks.
2791  /// When true, IsProfitableToFoldIntoAddressingMode always returns true.
2792  bool IgnoreProfitability;
2793 
2794  AddressingModeMatcher(
2796  const TargetRegisterInfo &TRI, Type *AT, unsigned AS, Instruction *MI,
2797  ExtAddrMode &AM, const SetOfInstrs &InsertedInsts,
2798  InstrToOrigTy &PromotedInsts, TypePromotionTransaction &TPT,
2799  std::pair<AssertingVH<GetElementPtrInst>, int64_t> &LargeOffsetGEP)
2800  : AddrModeInsts(AMI), TLI(TLI), TRI(TRI),
2801  DL(MI->getModule()->getDataLayout()), AccessTy(AT), AddrSpace(AS),
2802  MemoryInst(MI), AddrMode(AM), InsertedInsts(InsertedInsts),
2803  PromotedInsts(PromotedInsts), TPT(TPT), LargeOffsetGEP(LargeOffsetGEP) {
2804  IgnoreProfitability = false;
2805  }
2806 
2807 public:
2808  /// Find the maximal addressing mode that a load/store of V can fold,
2809  /// give an access type of AccessTy. This returns a list of involved
2810  /// instructions in AddrModeInsts.
2811  /// \p InsertedInsts The instructions inserted by other CodeGenPrepare
2812  /// optimizations.
2813  /// \p PromotedInsts maps the instructions to their type before promotion.
2814  /// \p The ongoing transaction where every action should be registered.
2815  static ExtAddrMode
2816  Match(Value *V, Type *AccessTy, unsigned AS, Instruction *MemoryInst,
2817  SmallVectorImpl<Instruction *> &AddrModeInsts,
2818  const TargetLowering &TLI, const TargetRegisterInfo &TRI,
2819  const SetOfInstrs &InsertedInsts, InstrToOrigTy &PromotedInsts,
2820  TypePromotionTransaction &TPT,
2821  std::pair<AssertingVH<GetElementPtrInst>, int64_t> &LargeOffsetGEP) {
2822  ExtAddrMode Result;
2823 
2824  bool Success = AddressingModeMatcher(AddrModeInsts, TLI, TRI, AccessTy, AS,
2825  MemoryInst, Result, InsertedInsts,
2826  PromotedInsts, TPT, LargeOffsetGEP)
2827  .matchAddr(V, 0);
2828  (void)Success; assert(Success && "Couldn't select *anything*?");
2829  return Result;
2830  }
2831 
2832 private:
2833  bool matchScaledValue(Value *ScaleReg, int64_t Scale, unsigned Depth);
2834  bool matchAddr(Value *Addr, unsigned Depth);
2835  bool matchOperationAddr(User *AddrInst, unsigned Opcode, unsigned Depth,
2836  bool *MovedAway = nullptr);
2837  bool isProfitableToFoldIntoAddressingMode(Instruction *I,
2838  ExtAddrMode &AMBefore,
2839  ExtAddrMode &AMAfter);
2840  bool valueAlreadyLiveAtInst(Value *Val, Value *KnownLive1, Value *KnownLive2);
2841  bool isPromotionProfitable(unsigned NewCost, unsigned OldCost,
2842  Value *PromotedOperand) const;
2843 };
2844 
2845 class PhiNodeSet;
2846 
2847 /// An iterator for PhiNodeSet.
2848 class PhiNodeSetIterator {
2849  PhiNodeSet * const Set;
2850  size_t CurrentIndex = 0;
2851 
2852 public:
2853  /// The constructor. Start should point to either a valid element, or be equal
2854  /// to the size of the underlying SmallVector of the PhiNodeSet.
2855  PhiNodeSetIterator(PhiNodeSet * const Set, size_t Start);
2856  PHINode * operator*() const;
2857  PhiNodeSetIterator& operator++();
2858  bool operator==(const PhiNodeSetIterator &RHS) const;
2859  bool operator!=(const PhiNodeSetIterator &RHS) const;
2860 };
2861 
2862 /// Keeps a set of PHINodes.
2863 ///
2864 /// This is a minimal set implementation for a specific use case:
2865 /// It is very fast when there are very few elements, but also provides good
2866 /// performance when there are many. It is similar to SmallPtrSet, but also
2867 /// provides iteration by insertion order, which is deterministic and stable
2868 /// across runs. It is also similar to SmallSetVector, but provides removing
2869 /// elements in O(1) time. This is achieved by not actually removing the element
2870 /// from the underlying vector, so comes at the cost of using more memory, but
2871 /// that is fine, since PhiNodeSets are used as short lived objects.
2872 class PhiNodeSet {
2873  friend class PhiNodeSetIterator;
2874 
2875  using MapType = SmallDenseMap<PHINode *, size_t, 32>;
2876  using iterator = PhiNodeSetIterator;
2877 
2878  /// Keeps the elements in the order of their insertion in the underlying
2879  /// vector. To achieve constant time removal, it never deletes any element.
2881 
2882  /// Keeps the elements in the underlying set implementation. This (and not the
2883  /// NodeList defined above) is the source of truth on whether an element
2884  /// is actually in the collection.
2885  MapType NodeMap;
2886 
2887  /// Points to the first valid (not deleted) element when the set is not empty
2888  /// and the value is not zero. Equals to the size of the underlying vector
2889  /// when the set is empty. When the value is 0, as in the beginning, the
2890  /// first element may or may not be valid.
2891  size_t FirstValidElement = 0;
2892 
2893 public:
2894  /// Inserts a new element to the collection.
2895  /// \returns true if the element is actually added, i.e. was not in the
2896  /// collection before the operation.
2897  bool insert(PHINode *Ptr) {
2898  if (NodeMap.insert(std::make_pair(Ptr, NodeList.size())).second) {
2899  NodeList.push_back(Ptr);
2900  return true;
2901  }
2902  return false;
2903  }
2904 
2905  /// Removes the element from the collection.
2906  /// \returns whether the element is actually removed, i.e. was in the
2907  /// collection before the operation.
2908  bool erase(PHINode *Ptr) {
2909  auto it = NodeMap.find(Ptr);
2910  if (it != NodeMap.end()) {
2911  NodeMap.erase(Ptr);
2912  SkipRemovedElements(FirstValidElement);
2913  return true;
2914  }
2915  return false;
2916  }
2917 
2918  /// Removes all elements and clears the collection.
2919  void clear() {
2920  NodeMap.clear();
2921  NodeList.clear();
2922  FirstValidElement = 0;
2923  }
2924 
2925  /// \returns an iterator that will iterate the elements in the order of
2926  /// insertion.
2927  iterator begin() {
2928  if (FirstValidElement == 0)
2929  SkipRemovedElements(FirstValidElement);
2930  return PhiNodeSetIterator(this, FirstValidElement);
2931  }
2932 
2933  /// \returns an iterator that points to the end of the collection.
2934  iterator end() { return PhiNodeSetIterator(this, NodeList.size()); }
2935 
2936  /// Returns the number of elements in the collection.
2937  size_t size() const {
2938  return NodeMap.size();
2939  }
2940 
2941  /// \returns 1 if the given element is in the collection, and 0 if otherwise.
2942  size_t count(PHINode *Ptr) const {
2943  return NodeMap.count(Ptr);
2944  }
2945 
2946 private:
2947  /// Updates the CurrentIndex so that it will point to a valid element.
2948  ///
2949  /// If the element of NodeList at CurrentIndex is valid, it does not
2950  /// change it. If there are no more valid elements, it updates CurrentIndex
2951  /// to point to the end of the NodeList.
2952  void SkipRemovedElements(size_t &CurrentIndex) {
2953  while (CurrentIndex < NodeList.size()) {
2954  auto it = NodeMap.find(NodeList[CurrentIndex]);
2955  // If the element has been deleted and added again later, NodeMap will
2956  // point to a different index, so CurrentIndex will still be invalid.
2957  if (it != NodeMap.end() && it->second == CurrentIndex)
2958  break;
2959  ++CurrentIndex;
2960  }
2961  }
2962 };
2963 
2964 PhiNodeSetIterator::PhiNodeSetIterator(PhiNodeSet *const Set, size_t Start)
2965  : Set(Set), CurrentIndex(Start) {}
2966 
2968  assert(CurrentIndex < Set->NodeList.size() &&
2969  "PhiNodeSet access out of range");
2970  return Set->NodeList[CurrentIndex];
2971 }
2972 
2973 PhiNodeSetIterator& PhiNodeSetIterator::operator++() {
2974  assert(CurrentIndex < Set->NodeList.size() &&
2975  "PhiNodeSet access out of range");
2976  ++CurrentIndex;
2977  Set->SkipRemovedElements(CurrentIndex);
2978  return *this;
2979 }
2980 
2981 bool PhiNodeSetIterator::operator==(const PhiNodeSetIterator &RHS) const {
2982  return CurrentIndex == RHS.CurrentIndex;
2983 }
2984 
2985 bool PhiNodeSetIterator::operator!=(const PhiNodeSetIterator &RHS) const {
2986  return !((*this) == RHS);
2987 }
2988 
2989 /// Keep track of simplification of Phi nodes.
2990 /// Accept the set of all phi nodes and erase phi node from this set
2991 /// if it is simplified.
2992 class SimplificationTracker {
2994  const SimplifyQuery &SQ;
2995  // Tracks newly created Phi nodes. The elements are iterated by insertion
2996  // order.
2997  PhiNodeSet AllPhiNodes;
2998  // Tracks newly created Select nodes.
2999  SmallPtrSet<SelectInst *, 32> AllSelectNodes;
3000 
3001 public:
3002  SimplificationTracker(const SimplifyQuery &sq)
3003  : SQ(sq) {}
3004 
3005  Value *Get(Value *V) {
3006  do {
3007  auto SV = Storage.find(V);
3008  if (SV == Storage.end())
3009  return V;
3010  V = SV->second;
3011  } while (true);
3012  }
3013 
3014  Value *Simplify(Value *Val) {
3015  SmallVector<Value *, 32> WorkList;
3016  SmallPtrSet<Value *, 32> Visited;
3017  WorkList.push_back(Val);
3018  while (!WorkList.empty()) {
3019  auto P = WorkList.pop_back_val();
3020  if (!Visited.insert(P).second)
3021  continue;
3022  if (auto *PI = dyn_cast<Instruction>(P))
3023  if (Value *V = SimplifyInstruction(cast<Instruction>(PI), SQ)) {
3024  for (auto *U : PI->users())
3025  WorkList.push_back(cast<Value>(U));
3026  Put(PI, V);
3027  PI->replaceAllUsesWith(V);
3028  if (auto *PHI = dyn_cast<PHINode>(PI))
3029  AllPhiNodes.erase(PHI);
3030  if (auto *Select = dyn_cast<SelectInst>(PI))
3031  AllSelectNodes.erase(Select);
3032  PI->eraseFromParent();
3033  }
3034  }
3035  return Get(Val);
3036  }
3037 
3038  void Put(Value *From, Value *To) {
3039  Storage.insert({ From, To });
3040  }
3041 
3042  void ReplacePhi(PHINode *From, PHINode *To) {
3043  Value* OldReplacement = Get(From);
3044  while (OldReplacement != From) {
3045  From = To;
3046  To = dyn_cast<PHINode>(OldReplacement);
3047  OldReplacement = Get(From);
3048  }
3049  assert(Get(To) == To && "Replacement PHI node is already replaced.");
3050  Put(From, To);
3051  From->replaceAllUsesWith(To);
3052  AllPhiNodes.erase(From);
3053  From->eraseFromParent();
3054  }
3055 
3056  PhiNodeSet& newPhiNodes() { return AllPhiNodes; }
3057 
3058  void insertNewPhi(PHINode *PN) { AllPhiNodes.insert(PN); }
3059 
3060  void insertNewSelect(SelectInst *SI) { AllSelectNodes.insert(SI); }
3061 
3062  unsigned countNewPhiNodes() const { return AllPhiNodes.size(); }
3063 
3064  unsigned countNewSelectNodes() const { return AllSelectNodes.size(); }
3065 
3066  void destroyNewNodes(Type *CommonType) {
3067  // For safe erasing, replace the uses with dummy value first.
3068  auto Dummy = UndefValue::get(CommonType);
3069  for (auto I : AllPhiNodes) {
3071  I->eraseFromParent();
3072  }
3073  AllPhiNodes.clear();
3074  for (auto I : AllSelectNodes) {
3076  I->eraseFromParent();
3077  }
3078  AllSelectNodes.clear();
3079  }
3080 };
3081 
3082 /// A helper class for combining addressing modes.
3083 class AddressingModeCombiner {
3084  typedef DenseMap<Value *, Value *> FoldAddrToValueMapping;
3085  typedef std::pair<PHINode *, PHINode *> PHIPair;
3086 
3087 private:
3088  /// The addressing modes we've collected.
3089  SmallVector<ExtAddrMode, 16> AddrModes;
3090 
3091  /// The field in which the AddrModes differ, when we have more than one.
3092  ExtAddrMode::FieldName DifferentField = ExtAddrMode::NoField;
3093 
3094  /// Are the AddrModes that we have all just equal to their original values?
3095  bool AllAddrModesTrivial = true;
3096 
3097  /// Common Type for all different fields in addressing modes.
3098  Type *CommonType;
3099 
3100  /// SimplifyQuery for simplifyInstruction utility.
3101  const SimplifyQuery &SQ;
3102 
3103  /// Original Address.
3104  Value *Original;
3105 
3106 public:
3107  AddressingModeCombiner(const SimplifyQuery &_SQ, Value *OriginalValue)
3108  : CommonType(nullptr), SQ(_SQ), Original(OriginalValue) {}
3109 
3110  /// Get the combined AddrMode
3111  const ExtAddrMode &getAddrMode() const {
3112  return AddrModes[0];
3113  }
3114 
3115  /// Add a new AddrMode if it's compatible with the AddrModes we already
3116  /// have.
3117  /// \return True iff we succeeded in doing so.
3118  bool addNewAddrMode(ExtAddrMode &NewAddrMode) {
3119  // Take note of if we have any non-trivial AddrModes, as we need to detect
3120  // when all AddrModes are trivial as then we would introduce a phi or select
3121  // which just duplicates what's already there.
3122  AllAddrModesTrivial = AllAddrModesTrivial && NewAddrMode.isTrivial();
3123 
3124  // If this is the first addrmode then everything is fine.
3125  if (AddrModes.empty()) {
3126  AddrModes.emplace_back(NewAddrMode);
3127  return true;
3128  }
3129 
3130  // Figure out how different this is from the other address modes, which we
3131  // can do just by comparing against the first one given that we only care
3132  // about the cumulative difference.
3133  ExtAddrMode::FieldName ThisDifferentField =
3134  AddrModes[0].compare(NewAddrMode);
3135  if (DifferentField == ExtAddrMode::NoField)
3136  DifferentField = ThisDifferentField;
3137  else if (DifferentField != ThisDifferentField)
3138  DifferentField = ExtAddrMode::MultipleFields;
3139 
3140  // If NewAddrMode differs in more than one dimension we cannot handle it.
3141  bool CanHandle = DifferentField != ExtAddrMode::MultipleFields;
3142 
3143  // If Scale Field is different then we reject.
3144  CanHandle = CanHandle && DifferentField != ExtAddrMode::ScaleField;
3145 
3146  // We also must reject the case when base offset is different and
3147  // scale reg is not null, we cannot handle this case due to merge of
3148  // different offsets will be used as ScaleReg.
3149  CanHandle = CanHandle && (DifferentField != ExtAddrMode::BaseOffsField ||
3150  !NewAddrMode.ScaledReg);
3151 
3152  // We also must reject the case when GV is different and BaseReg installed
3153  // due to we want to use base reg as a merge of GV values.
3154  CanHandle = CanHandle && (DifferentField != ExtAddrMode::BaseGVField ||
3155  !NewAddrMode.HasBaseReg);
3156 
3157  // Even if NewAddMode is the same we still need to collect it due to
3158  // original value is different. And later we will need all original values
3159  // as anchors during finding the common Phi node.
3160  if (CanHandle)
3161  AddrModes.emplace_back(NewAddrMode);
3162  else
3163  AddrModes.clear();
3164 
3165  return CanHandle;
3166  }
3167 
3168  /// Combine the addressing modes we've collected into a single
3169  /// addressing mode.
3170  /// \return True iff we successfully combined them or we only had one so
3171  /// didn't need to combine them anyway.
3172  bool combineAddrModes() {
3173  // If we have no AddrModes then they can't be combined.
3174  if (AddrModes.size() == 0)
3175  return false;
3176 
3177  // A single AddrMode can trivially be combined.
3178  if (AddrModes.size() == 1 || DifferentField == ExtAddrMode::NoField)
3179  return true;
3180 
3181  // If the AddrModes we collected are all just equal to the value they are
3182  // derived from then combining them wouldn't do anything useful.
3183  if (AllAddrModesTrivial)
3184  return false;
3185 
3186  if (!addrModeCombiningAllowed())
3187  return false;
3188 
3189  // Build a map between <original value, basic block where we saw it> to
3190  // value of base register.
3191  // Bail out if there is no common type.
3192  FoldAddrToValueMapping Map;
3193  if (!initializeMap(Map))
3194  return false;
3195 
3196  Value *CommonValue = findCommon(Map);
3197  if (CommonValue)
3198  AddrModes[0].SetCombinedField(DifferentField, CommonValue, AddrModes);
3199  return CommonValue != nullptr;
3200  }
3201 
3202 private:
3203  /// Initialize Map with anchor values. For address seen
3204  /// we set the value of different field saw in this address.
3205  /// At the same time we find a common type for different field we will
3206  /// use to create new Phi/Select nodes. Keep it in CommonType field.
3207  /// Return false if there is no common type found.
3208  bool initializeMap(FoldAddrToValueMapping &Map) {
3209  // Keep track of keys where the value is null. We will need to replace it
3210  // with constant null when we know the common type.
3211  SmallVector<Value *, 2> NullValue;
3212  Type *IntPtrTy = SQ.DL.getIntPtrType(AddrModes[0].OriginalValue->getType());
3213  for (auto &AM : AddrModes) {
3214  Value *DV = AM.GetFieldAsValue(DifferentField, IntPtrTy);
3215  if (DV) {
3216  auto *Type = DV->getType();
3217  if (CommonType && CommonType != Type)
3218  return false;
3219  CommonType = Type;
3220  Map[AM.OriginalValue] = DV;
3221  } else {
3222  NullValue.push_back(AM.OriginalValue);
3223  }
3224  }
3225  assert(CommonType && "At least one non-null value must be!");
3226  for (auto *V : NullValue)
3227  Map[V] = Constant::getNullValue(CommonType);
3228  return true;
3229  }
3230 
3231  /// We have mapping between value A and other value B where B was a field in
3232  /// addressing mode represented by A. Also we have an original value C
3233  /// representing an address we start with. Traversing from C through phi and
3234  /// selects we ended up with A's in a map. This utility function tries to find
3235  /// a value V which is a field in addressing mode C and traversing through phi
3236  /// nodes and selects we will end up in corresponded values B in a map.
3237  /// The utility will create a new Phi/Selects if needed.
3238  // The simple example looks as follows:
3239  // BB1:
3240  // p1 = b1 + 40
3241  // br cond BB2, BB3
3242  // BB2:
3243  // p2 = b2 + 40
3244  // br BB3
3245  // BB3:
3246  // p = phi [p1, BB1], [p2, BB2]
3247  // v = load p
3248  // Map is
3249  // p1 -> b1
3250  // p2 -> b2
3251  // Request is
3252  // p -> ?
3253  // The function tries to find or build phi [b1, BB1], [b2, BB2] in BB3.
3254  Value *findCommon(FoldAddrToValueMapping &Map) {
3255  // Tracks the simplification of newly created phi nodes. The reason we use
3256  // this mapping is because we will add new created Phi nodes in AddrToBase.
3257  // Simplification of Phi nodes is recursive, so some Phi node may
3258  // be simplified after we added it to AddrToBase. In reality this
3259  // simplification is possible only if original phi/selects were not
3260  // simplified yet.
3261  // Using this mapping we can find the current value in AddrToBase.
3262  SimplificationTracker ST(SQ);
3263 
3264  // First step, DFS to create PHI nodes for all intermediate blocks.
3265  // Also fill traverse order for the second step.
3266  SmallVector<Value *, 32> TraverseOrder;
3267  InsertPlaceholders(Map, TraverseOrder, ST);
3268 
3269  // Second Step, fill new nodes by merged values and simplify if possible.
3270  FillPlaceholders(Map, TraverseOrder, ST);
3271 
3272  if (!AddrSinkNewSelects && ST.countNewSelectNodes() > 0) {
3273  ST.destroyNewNodes(CommonType);
3274  return nullptr;
3275  }
3276 
3277  // Now we'd like to match New Phi nodes to existed ones.
3278  unsigned PhiNotMatchedCount = 0;
3279  if (!MatchPhiSet(ST, AddrSinkNewPhis, PhiNotMatchedCount)) {
3280  ST.destroyNewNodes(CommonType);
3281  return nullptr;
3282  }
3283 
3284  auto *Result = ST.Get(Map.find(Original)->second);
3285  if (Result) {
3286  NumMemoryInstsPhiCreated += ST.countNewPhiNodes() + PhiNotMatchedCount;
3287  NumMemoryInstsSelectCreated += ST.countNewSelectNodes();
3288  }
3289  return Result;
3290  }
3291 
3292  /// Try to match PHI node to Candidate.
3293  /// Matcher tracks the matched Phi nodes.
3294  bool MatchPhiNode(PHINode *PHI, PHINode *Candidate,
3295  SmallSetVector<PHIPair, 8> &Matcher,
3296  PhiNodeSet &PhiNodesToMatch) {
3297  SmallVector<PHIPair, 8> WorkList;
3298  Matcher.insert({ PHI, Candidate });
3299  SmallSet<PHINode *, 8> MatchedPHIs;
3300  MatchedPHIs.insert(PHI);
3301  WorkList.push_back({ PHI, Candidate });
3302  SmallSet<PHIPair, 8> Visited;
3303  while (!WorkList.empty()) {
3304  auto Item = WorkList.pop_back_val();
3305  if (!Visited.insert(Item).second)
3306  continue;
3307  // We iterate over all incoming values to Phi to compare them.
3308  // If values are different and both of them Phi and the first one is a
3309  // Phi we added (subject to match) and both of them is in the same basic
3310  // block then we can match our pair if values match. So we state that
3311  // these values match and add it to work list to verify that.
3312  for (auto B : Item.first->blocks()) {
3313  Value *FirstValue = Item.first->getIncomingValueForBlock(B);
3314  Value *SecondValue = Item.second->getIncomingValueForBlock(B);
3315  if (FirstValue == SecondValue)
3316  continue;
3317 
3318  PHINode *FirstPhi = dyn_cast<PHINode>(FirstValue);
3319  PHINode *SecondPhi = dyn_cast<PHINode>(SecondValue);
3320 
3321  // One of them is not Phi or
3322  // The first one is not Phi node from the set we'd like to match or
3323  // Phi nodes from different basic blocks then
3324  // we will not be able to match.
3325  if (!FirstPhi || !SecondPhi || !PhiNodesToMatch.count(FirstPhi) ||
3326  FirstPhi->getParent() != SecondPhi->getParent())
3327  return false;
3328 
3329  // If we already matched them then continue.
3330  if (Matcher.count({ FirstPhi, SecondPhi }))
3331  continue;
3332  // So the values are different and does not match. So we need them to
3333  // match. (But we register no more than one match per PHI node, so that
3334  // we won't later try to replace them twice.)
3335  if (!MatchedPHIs.insert(FirstPhi).second)
3336  Matcher.insert({ FirstPhi, SecondPhi });
3337  // But me must check it.
3338  WorkList.push_back({ FirstPhi, SecondPhi });
3339  }
3340  }
3341  return true;
3342  }
3343 
3344  /// For the given set of PHI nodes (in the SimplificationTracker) try
3345  /// to find their equivalents.
3346  /// Returns false if this matching fails and creation of new Phi is disabled.
3347  bool MatchPhiSet(SimplificationTracker &ST, bool AllowNewPhiNodes,
3348  unsigned &PhiNotMatchedCount) {
3349  // Matched and PhiNodesToMatch iterate their elements in a deterministic
3350  // order, so the replacements (ReplacePhi) are also done in a deterministic
3351  // order.
3353  SmallPtrSet<PHINode *, 8> WillNotMatch;
3354  PhiNodeSet &PhiNodesToMatch = ST.newPhiNodes();
3355  while (PhiNodesToMatch.size()) {
3356  PHINode *PHI = *PhiNodesToMatch.begin();
3357 
3358  // Add us, if no Phi nodes in the basic block we do not match.
3359  WillNotMatch.clear();
3360  WillNotMatch.insert(PHI);
3361 
3362  // Traverse all Phis until we found equivalent or fail to do that.
3363  bool IsMatched = false;
3364  for (auto &P : PHI->getParent()->phis()) {
3365  if (&P == PHI)
3366  continue;
3367  if ((IsMatched = MatchPhiNode(PHI, &P, Matched, PhiNodesToMatch)))
3368  break;
3369  // If it does not match, collect all Phi nodes from matcher.
3370  // if we end up with no match, them all these Phi nodes will not match
3371  // later.
3372  for (auto M : Matched)
3373  WillNotMatch.insert(M.first);
3374  Matched.clear();
3375  }
3376  if (IsMatched) {
3377  // Replace all matched values and erase them.
3378  for (auto MV : Matched)
3379  ST.ReplacePhi(MV.first, MV.second);
3380  Matched.clear();
3381  continue;
3382  }
3383  // If we are not allowed to create new nodes then bail out.
3384  if (!AllowNewPhiNodes)
3385  return false;
3386  // Just remove all seen values in matcher. They will not match anything.
3387  PhiNotMatchedCount += WillNotMatch.size();
3388  for (auto *P : WillNotMatch)
3389  PhiNodesToMatch.erase(P);
3390  }
3391  return true;
3392  }
3393  /// Fill the placeholders with values from predecessors and simplify them.
3394  void FillPlaceholders(FoldAddrToValueMapping &Map,
3395  SmallVectorImpl<Value *> &TraverseOrder,
3396  SimplificationTracker &ST) {
3397  while (!TraverseOrder.empty()) {
3398  Value *Current = TraverseOrder.pop_back_val();
3399  assert(Map.find(Current) != Map.end() && "No node to fill!!!");
3400  Value *V = Map[Current];
3401 
3402  if (SelectInst *Select = dyn_cast<SelectInst>(V)) {
3403  // CurrentValue also must be Select.
3404  auto *CurrentSelect = cast<SelectInst>(Current);
3405  auto *TrueValue = CurrentSelect->getTrueValue();
3406  assert(Map.find(TrueValue) != Map.end() && "No True Value!");
3407  Select->setTrueValue(ST.Get(Map[TrueValue]));
3408  auto *FalseValue = CurrentSelect->getFalseValue();
3409  assert(Map.find(FalseValue) != Map.end() && "No False Value!");
3410  Select->setFalseValue(ST.Get(Map[FalseValue]));
3411  } else {
3412  // Must be a Phi node then.
3413  PHINode *PHI = cast<PHINode>(V);
3414  auto *CurrentPhi = dyn_cast<PHINode>(Current);
3415  // Fill the Phi node with values from predecessors.
3416  for (auto B : predecessors(PHI->getParent())) {
3417  Value *PV = CurrentPhi->getIncomingValueForBlock(B);
3418  assert(Map.find(PV) != Map.end() && "No predecessor Value!");
3419  PHI->addIncoming(ST.Get(Map[PV]), B);
3420  }
3421  }
3422  Map[Current] = ST.Simplify(V);
3423  }
3424  }
3425 
3426  /// Starting from original value recursively iterates over def-use chain up to
3427  /// known ending values represented in a map. For each traversed phi/select
3428  /// inserts a placeholder Phi or Select.
3429  /// Reports all new created Phi/Select nodes by adding them to set.
3430  /// Also reports and order in what values have been traversed.
3431  void InsertPlaceholders(FoldAddrToValueMapping &Map,
3432  SmallVectorImpl<Value *> &TraverseOrder,
3433  SimplificationTracker &ST) {
3434  SmallVector<Value *, 32> Worklist;
3435  assert((isa<PHINode>(Original) || isa<SelectInst>(Original)) &&
3436  "Address must be a Phi or Select node");
3437  auto *Dummy = UndefValue::get(CommonType);
3438  Worklist.push_back(Original);
3439  while (!Worklist.empty()) {
3440  Value *Current = Worklist.pop_back_val();
3441  // if it is already visited or it is an ending value then skip it.
3442  if (Map.find(Current) != Map.end())
3443  continue;
3444  TraverseOrder.push_back(Current);
3445 
3446  // CurrentValue must be a Phi node or select. All others must be covered
3447  // by anchors.
3448  if (SelectInst *CurrentSelect = dyn_cast<SelectInst>(Current)) {
3449  // Is it OK to get metadata from OrigSelect?!
3450  // Create a Select placeholder with dummy value.
3452  CurrentSelect->getCondition(), Dummy, Dummy,
3453  CurrentSelect->getName(), CurrentSelect, CurrentSelect);
3454  Map[Current] = Select;
3455  ST.insertNewSelect(Select);
3456  // We are interested in True and False values.
3457  Worklist.push_back(CurrentSelect->getTrueValue());
3458  Worklist.push_back(CurrentSelect->getFalseValue());
3459  } else {
3460  // It must be a Phi node then.
3461  PHINode *CurrentPhi = cast<PHINode>(Current);
3462  unsigned PredCount = CurrentPhi->getNumIncomingValues();
3463  PHINode *PHI =
3464  PHINode::Create(CommonType, PredCount, "sunk_phi", CurrentPhi);
3465  Map[Current] = PHI;
3466  ST.insertNewPhi(PHI);
3467  for (Value *P : CurrentPhi->incoming_values())
3468  Worklist.push_back(P);
3469  }
3470  }
3471  }
3472 
3473  bool addrModeCombiningAllowed() {
3475  return false;
3476  switch (DifferentField) {
3477  default:
3478  return false;
3479  case ExtAddrMode::BaseRegField:
3480  return AddrSinkCombineBaseReg;
3481  case ExtAddrMode::BaseGVField:
3482  return AddrSinkCombineBaseGV;
3483  case ExtAddrMode::BaseOffsField:
3484  return AddrSinkCombineBaseOffs;
3485  case ExtAddrMode::ScaledRegField:
3486  return AddrSinkCombineScaledReg;
3487  }
3488  }
3489 };
3490 } // end anonymous namespace
3491 
3492 /// Try adding ScaleReg*Scale to the current addressing mode.
3493 /// Return true and update AddrMode if this addr mode is legal for the target,
3494 /// false if not.
3495 bool AddressingModeMatcher::matchScaledValue(Value *ScaleReg, int64_t Scale,
3496  unsigned Depth) {
3497  // If Scale is 1, then this is the same as adding ScaleReg to the addressing
3498  // mode. Just process that directly.
3499  if (Scale == 1)
3500  return matchAddr(ScaleReg, Depth);
3501 
3502  // If the scale is 0, it takes nothing to add this.
3503  if (Scale == 0)
3504  return true;
3505 
3506  // If we already have a scale of this value, we can add to it, otherwise, we
3507  // need an available scale field.
3508  if (AddrMode.Scale != 0 && AddrMode.ScaledReg != ScaleReg)
3509  return false;
3510 
3511  ExtAddrMode TestAddrMode = AddrMode;
3512 
3513  // Add scale to turn X*4+X*3 -> X*7. This could also do things like
3514  // [A+B + A*7] -> [B+A*8].
3515  TestAddrMode.Scale += Scale;
3516  TestAddrMode.ScaledReg = ScaleReg;
3517 
3518  // If the new address isn't legal, bail out.
3519  if (!TLI.isLegalAddressingMode(DL, TestAddrMode, AccessTy, AddrSpace))
3520  return false;
3521 
3522  // It was legal, so commit it.
3523  AddrMode = TestAddrMode;
3524 
3525  // Okay, we decided that we can add ScaleReg+Scale to AddrMode. Check now
3526  // to see if ScaleReg is actually X+C. If so, we can turn this into adding
3527  // X*Scale + C*Scale to addr mode.
3528  ConstantInt *CI = nullptr; Value *AddLHS = nullptr;
3529  if (isa<Instruction>(ScaleReg) && // not a constant expr.
3530  match(ScaleReg, m_Add(m_Value(AddLHS), m_ConstantInt(CI)))) {
3531  TestAddrMode.InBounds = false;
3532  TestAddrMode.ScaledReg = AddLHS;
3533  TestAddrMode.BaseOffs += CI->getSExtValue()*TestAddrMode.Scale;
3534 
3535  // If this addressing mode is legal, commit it and remember that we folded
3536  // this instruction.
3537  if (TLI.isLegalAddressingMode(DL, TestAddrMode, AccessTy, AddrSpace)) {
3538  AddrModeInsts.push_back(cast<Instruction>(ScaleReg));
3539  AddrMode = TestAddrMode;
3540  return true;
3541  }
3542  }
3543 
3544  // Otherwise, not (x+c)*scale, just return what we have.
3545  return true;
3546 }
3547 
3548 /// This is a little filter, which returns true if an addressing computation
3549 /// involving I might be folded into a load/store accessing it.
3550 /// This doesn't need to be perfect, but needs to accept at least
3551 /// the set of instructions that MatchOperationAddr can.
3553  switch (I->getOpcode()) {
3554  case Instruction::BitCast:
3555  case Instruction::AddrSpaceCast:
3556  // Don't touch identity bitcasts.
3557  if (I->getType() == I->getOperand(0)->getType())
3558  return false;
3559  return I->getType()->isIntOrPtrTy();
3560  case Instruction::PtrToInt:
3561  // PtrToInt is always a noop, as we know that the int type is pointer sized.
3562  return true;
3563  case Instruction::IntToPtr:
3564  // We know the input is intptr_t, so this is foldable.
3565  return true;
3566  case Instruction::Add:
3567  return true;
3568  case Instruction::Mul:
3569  case Instruction::Shl:
3570  // Can only handle X*C and X << C.
3571  return isa<ConstantInt>(I->getOperand(1));
3572  case Instruction::GetElementPtr:
3573  return true;
3574  default:
3575  return false;
3576  }
3577 }
3578 
3579 /// Check whether or not \p Val is a legal instruction for \p TLI.
3580 /// \note \p Val is assumed to be the product of some type promotion.
3581 /// Therefore if \p Val has an undefined state in \p TLI, this is assumed
3582 /// to be legal, as the non-promoted value would have had the same state.
3584  const DataLayout &DL, Value *Val) {
3585  Instruction *PromotedInst = dyn_cast<Instruction>(Val);
3586  if (!PromotedInst)
3587  return false;
3588  int ISDOpcode = TLI.InstructionOpcodeToISD(PromotedInst->getOpcode());
3589  // If the ISDOpcode is undefined, it was undefined before the promotion.
3590  if (!ISDOpcode)
3591  return true;
3592  // Otherwise, check if the promoted instruction is legal or not.
3593  return TLI.isOperationLegalOrCustom(
3594  ISDOpcode, TLI.getValueType(DL, PromotedInst->getType()));
3595 }
3596 
3597 namespace {
3598 
3599 /// Hepler class to perform type promotion.
3600 class TypePromotionHelper {
3601  /// Utility function to add a promoted instruction \p ExtOpnd to
3602  /// \p PromotedInsts and record the type of extension we have seen.
3603  static void addPromotedInst(InstrToOrigTy &PromotedInsts,
3604  Instruction *ExtOpnd,
3605  bool IsSExt) {
3606  ExtType ExtTy = IsSExt ? SignExtension : ZeroExtension;
3607  InstrToOrigTy::iterator It = PromotedInsts.find(ExtOpnd);
3608  if (It != PromotedInsts.end()) {
3609  // If the new extension is same as original, the information in
3610  // PromotedInsts[ExtOpnd] is still correct.
3611  if (It->second.getInt() == ExtTy)
3612  return;
3613 
3614  // Now the new extension is different from old extension, we make
3615  // the type information invalid by setting extension type to
3616  // BothExtension.
3617  ExtTy = BothExtension;
3618  }
3619  PromotedInsts[ExtOpnd] = TypeIsSExt(ExtOpnd->getType(), ExtTy);
3620  }
3621 
3622  /// Utility function to query the original type of instruction \p Opnd
3623  /// with a matched extension type. If the extension doesn't match, we
3624  /// cannot use the information we had on the original type.
3625  /// BothExtension doesn't match any extension type.
3626  static const Type *getOrigType(const InstrToOrigTy &PromotedInsts,
3627  Instruction *Opnd,
3628  bool IsSExt) {
3629  ExtType ExtTy = IsSExt ? SignExtension : ZeroExtension;
3630  InstrToOrigTy::const_iterator It = PromotedInsts.find(Opnd);
3631  if (It != PromotedInsts.end() && It->second.getInt() == ExtTy)
3632  return It->second.getPointer();
3633  return nullptr;
3634  }
3635 
3636  /// Utility function to check whether or not a sign or zero extension
3637  /// of \p Inst with \p ConsideredExtType can be moved through \p Inst by
3638  /// either using the operands of \p Inst or promoting \p Inst.
3639  /// The type of the extension is defined by \p IsSExt.
3640  /// In other words, check if:
3641  /// ext (Ty Inst opnd1 opnd2 ... opndN) to ConsideredExtType.
3642  /// #1 Promotion applies:
3643  /// ConsideredExtType Inst (ext opnd1 to ConsideredExtType, ...).
3644  /// #2 Operand reuses:
3645  /// ext opnd1 to ConsideredExtType.
3646  /// \p PromotedInsts maps the instructions to their type before promotion.
3647  static bool canGetThrough(const Instruction *Inst, Type *ConsideredExtType,
3648  const InstrToOrigTy &PromotedInsts, bool IsSExt);
3649 
3650  /// Utility function to determine if \p OpIdx should be promoted when
3651  /// promoting \p Inst.
3652  static bool shouldExtOperand(const Instruction *Inst, int OpIdx) {
3653  return !(isa<SelectInst>(Inst) && OpIdx == 0);
3654  }
3655 
3656  /// Utility function to promote the operand of \p Ext when this
3657  /// operand is a promotable trunc or sext or zext.
3658  /// \p PromotedInsts maps the instructions to their type before promotion.
3659  /// \p CreatedInstsCost[out] contains the cost of all instructions
3660  /// created to promote the operand of Ext.
3661  /// Newly added extensions are inserted in \p Exts.
3662  /// Newly added truncates are inserted in \p Truncs.
3663  /// Should never be called directly.
3664  /// \return The promoted value which is used instead of Ext.
3665  static Value *promoteOperandForTruncAndAnyExt(
3666  Instruction *Ext, TypePromotionTransaction &TPT,
3667  InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
3669  SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI);
3670 
3671  /// Utility function to promote the operand of \p Ext when this
3672  /// operand is promotable and is not a supported trunc or sext.
3673  /// \p PromotedInsts maps the instructions to their type before promotion.
3674  /// \p CreatedInstsCost[out] contains the cost of all the instructions
3675  /// created to promote the operand of Ext.
3676  /// Newly added extensions are inserted in \p Exts.
3677  /// Newly added truncates are inserted in \p Truncs.
3678  /// Should never be called directly.
3679  /// \return The promoted value which is used instead of Ext.
3680  static Value *promoteOperandForOther(Instruction *Ext,
3681  TypePromotionTransaction &TPT,
3682  InstrToOrigTy &PromotedInsts,
3683  unsigned &CreatedInstsCost,
3686  const TargetLowering &TLI, bool IsSExt);
3687 
3688  /// \see promoteOperandForOther.
3689  static Value *signExtendOperandForOther(
3690  Instruction *Ext, TypePromotionTransaction &TPT,
3691  InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
3693  SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI) {
3694  return promoteOperandForOther(Ext, TPT, PromotedInsts, CreatedInstsCost,
3695  Exts, Truncs, TLI, true);
3696  }
3697 
3698  /// \see promoteOperandForOther.
3699  static Value *zeroExtendOperandForOther(
3700  Instruction *Ext, TypePromotionTransaction &TPT,
3701  InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
3703  SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI) {
3704  return promoteOperandForOther(Ext, TPT, PromotedInsts, CreatedInstsCost,
3705  Exts, Truncs, TLI, false);
3706  }
3707 
3708 public:
3709  /// Type for the utility function that promotes the operand of Ext.
3710  using Action = Value *(*)(Instruction *Ext, TypePromotionTransaction &TPT,
3711  InstrToOrigTy &PromotedInsts,
3712  unsigned &CreatedInstsCost,
3715  const TargetLowering &TLI);
3716 
3717  /// Given a sign/zero extend instruction \p Ext, return the appropriate
3718  /// action to promote the operand of \p Ext instead of using Ext.
3719  /// \return NULL if no promotable action is possible with the current
3720  /// sign extension.
3721  /// \p InsertedInsts keeps track of all the instructions inserted by the
3722  /// other CodeGenPrepare optimizations. This information is important
3723  /// because we do not want to promote these instructions as CodeGenPrepare
3724  /// will reinsert them later. Thus creating an infinite loop: create/remove.
3725  /// \p PromotedInsts maps the instructions to their type before promotion.
3726  static Action getAction(Instruction *Ext, const SetOfInstrs &InsertedInsts,
3727  const TargetLowering &TLI,
3728  const InstrToOrigTy &PromotedInsts);
3729 };
3730 
3731 } // end anonymous namespace
3732 
3733 bool TypePromotionHelper::canGetThrough(const Instruction *Inst,
3734  Type *ConsideredExtType,
3735  const InstrToOrigTy &PromotedInsts,
3736  bool IsSExt) {
3737  // The promotion helper does not know how to deal with vector types yet.
3738  // To be able to fix that, we would need to fix the places where we
3739  // statically extend, e.g., constants and such.
3740  if (Inst->getType()->isVectorTy())
3741  return false;
3742 
3743  // We can always get through zext.
3744  if (isa<ZExtInst>(Inst))
3745  return true;
3746 
3747  // sext(sext) is ok too.
3748  if (IsSExt && isa<SExtInst>(Inst))
3749  return true;
3750 
3751  // We can get through binary operator, if it is legal. In other words, the
3752  // binary operator must have a nuw or nsw flag.
3753  const BinaryOperator *BinOp = dyn_cast<BinaryOperator>(Inst);
3754  if (BinOp && isa<OverflowingBinaryOperator>(BinOp) &&
3755  ((!IsSExt && BinOp->hasNoUnsignedWrap()) ||
3756  (IsSExt && BinOp->hasNoSignedWrap())))
3757  return true;
3758 
3759  // ext(and(opnd, cst)) --> and(ext(opnd), ext(cst))
3760  if ((Inst->getOpcode() == Instruction::And ||
3761  Inst->getOpcode() == Instruction::Or))
3762  return true;
3763 
3764  // ext(xor(opnd, cst)) --> xor(ext(opnd), ext(cst))
3765  if (Inst->getOpcode() == Instruction::Xor) {
3766  const ConstantInt *Cst = dyn_cast<ConstantInt>(Inst->getOperand(1));
3767  // Make sure it is not a NOT.
3768  if (Cst && !Cst->getValue().isAllOnesValue())
3769  return true;
3770  }
3771 
3772  // zext(shrl(opnd, cst)) --> shrl(zext(opnd), zext(cst))
3773  // It may change a poisoned value into a regular value, like
3774  // zext i32 (shrl i8 %val, 12) --> shrl i32 (zext i8 %val), 12
3775  // poisoned value regular value
3776  // It should be OK since undef covers valid value.
3777  if (Inst->getOpcode() == Instruction::LShr && !IsSExt)
3778  return true;
3779 
3780  // and(ext(shl(opnd, cst)), cst) --> and(shl(ext(opnd), ext(cst)), cst)
3781  // It may change a poisoned value into a regular value, like
3782  // zext i32 (shl i8 %val, 12) --> shl i32 (zext i8 %val), 12
3783  // poisoned value regular value
3784  // It should be OK since undef covers valid value.
3785  if (Inst->getOpcode() == Instruction::Shl && Inst->hasOneUse()) {
3786  const Instruction *ExtInst =
3787  dyn_cast<const Instruction>(*Inst->user_begin());
3788  if (ExtInst->hasOneUse()) {
3789  const Instruction *AndInst =
3790  dyn_cast<const Instruction>(*ExtInst->user_begin());
3791  if (AndInst && AndInst->getOpcode() == Instruction::And) {
3792  const ConstantInt *Cst = dyn_cast<ConstantInt>(AndInst->getOperand(1));
3793  if (Cst &&
3794  Cst->getValue().isIntN(Inst->getType()->getIntegerBitWidth()))
3795  return true;
3796  }
3797  }
3798  }
3799 
3800  // Check if we can do the following simplification.
3801  // ext(trunc(opnd)) --> ext(opnd)
3802  if (!isa<TruncInst>(Inst))
3803  return false;
3804 
3805  Value *OpndVal = Inst->getOperand(0);
3806  // Check if we can use this operand in the extension.
3807  // If the type is larger than the result type of the extension, we cannot.
3808  if (!OpndVal->getType()->isIntegerTy() ||
3809  OpndVal->getType()->getIntegerBitWidth() >
3810  ConsideredExtType->getIntegerBitWidth())
3811  return false;
3812 
3813  // If the operand of the truncate is not an instruction, we will not have
3814  // any information on the dropped bits.
3815  // (Actually we could for constant but it is not worth the extra logic).
3816  Instruction *Opnd = dyn_cast<Instruction>(OpndVal);
3817  if (!Opnd)
3818  return false;
3819 
3820  // Check if the source of the type is narrow enough.
3821  // I.e., check that trunc just drops extended bits of the same kind of
3822  // the extension.
3823  // #1 get the type of the operand and check the kind of the extended bits.
3824  const Type *OpndType = getOrigType(PromotedInsts, Opnd, IsSExt);
3825  if (OpndType)
3826  ;
3827  else if ((IsSExt && isa<SExtInst>(Opnd)) || (!IsSExt && isa<ZExtInst>(Opnd)))
3828  OpndType = Opnd->getOperand(0)->getType();
3829  else
3830  return false;
3831 
3832  // #2 check that the truncate just drops extended bits.
3833  return Inst->getType()->getIntegerBitWidth() >=
3834  OpndType->getIntegerBitWidth();
3835 }
3836 
3837 TypePromotionHelper::Action TypePromotionHelper::getAction(
3838  Instruction *Ext, const SetOfInstrs &InsertedInsts,
3839  const TargetLowering &TLI, const InstrToOrigTy &PromotedInsts) {
3840  assert((isa<SExtInst>(Ext) || isa<ZExtInst>(Ext)) &&
3841  "Unexpected instruction type");
3842  Instruction *ExtOpnd = dyn_cast<Instruction>(Ext->getOperand(0));
3843  Type *ExtTy = Ext->getType();
3844  bool IsSExt = isa<SExtInst>(Ext);
3845  // If the operand of the extension is not an instruction, we cannot
3846  // get through.
3847  // If it, check we can get through.
3848  if (!ExtOpnd || !canGetThrough(ExtOpnd, ExtTy, PromotedInsts, IsSExt))
3849  return nullptr;
3850 
3851  // Do not promote if the operand has been added by codegenprepare.
3852  // Otherwise, it means we are undoing an optimization that is likely to be
3853  // redone, thus causing potential infinite loop.
3854  if (isa<TruncInst>(ExtOpnd) && InsertedInsts.count(ExtOpnd))
3855  return nullptr;
3856 
3857  // SExt or Trunc instructions.
3858  // Return the related handler.
3859  if (isa<SExtInst>(ExtOpnd) || isa<TruncInst>(ExtOpnd) ||
3860  isa<ZExtInst>(ExtOpnd))
3861  return promoteOperandForTruncAndAnyExt;
3862 
3863  // Regular instruction.
3864  // Abort early if we will have to insert non-free instructions.
3865  if (!ExtOpnd->hasOneUse() && !TLI.isTruncateFree(ExtTy, ExtOpnd->getType()))
3866  return nullptr;
3867  return IsSExt ? signExtendOperandForOther : zeroExtendOperandForOther;
3868 }
3869 
3870 Value *TypePromotionHelper::promoteOperandForTruncAndAnyExt(
3871  Instruction *SExt, TypePromotionTransaction &TPT,
3872  InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
3874  SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI) {
3875  // By construction, the operand of SExt is an instruction. Otherwise we cannot
3876  // get through it and this method should not be called.
3877  Instruction *SExtOpnd = cast<Instruction>(SExt->getOperand(0));
3878  Value *ExtVal = SExt;
3879  bool HasMergedNonFreeExt = false;
3880  if (isa<ZExtInst>(SExtOpnd)) {
3881  // Replace s|zext(zext(opnd))
3882  // => zext(opnd).
3883  HasMergedNonFreeExt = !TLI.isExtFree(SExtOpnd);
3884  Value *ZExt =
3885  TPT.createZExt(SExt, SExtOpnd->getOperand(0), SExt->getType());
3886  TPT.replaceAllUsesWith(SExt, ZExt);
3887  TPT.eraseInstruction(SExt);
3888  ExtVal = ZExt;
3889  } else {
3890  // Replace z|sext(trunc(opnd)) or sext(sext(opnd))
3891  // => z|sext(opnd).
3892  TPT.setOperand(SExt, 0, SExtOpnd->getOperand(0));
3893  }
3894  CreatedInstsCost = 0;
3895 
3896  // Remove dead code.
3897  if (SExtOpnd->use_empty())
3898  TPT.eraseInstruction(SExtOpnd);
3899 
3900  // Check if the extension is still needed.
3901  Instruction *ExtInst = dyn_cast<Instruction>(ExtVal);
3902  if (!ExtInst || ExtInst->getType() != ExtInst->getOperand(0)->getType()) {
3903  if (ExtInst) {
3904  if (Exts)
3905  Exts->push_back(ExtInst);
3906  CreatedInstsCost = !TLI.isExtFree(ExtInst) && !HasMergedNonFreeExt;
3907  }
3908  return ExtVal;
3909  }
3910 
3911  // At this point we have: ext ty opnd to ty.
3912  // Reassign the uses of ExtInst to the opnd and remove ExtInst.
3913  Value *NextVal = ExtInst->getOperand(0);
3914  TPT.eraseInstruction(ExtInst, NextVal);
3915  return NextVal;
3916 }
3917 
3918 Value *TypePromotionHelper::promoteOperandForOther(
3919  Instruction *Ext, TypePromotionTransaction &TPT,
3920  InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
3922  SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI,
3923  bool IsSExt) {
3924  // By construction, the operand of Ext is an instruction. Otherwise we cannot
3925  // get through it and this method should not be called.
3926  Instruction *ExtOpnd = cast<Instruction>(Ext->getOperand(0));
3927  CreatedInstsCost = 0;
3928  if (!ExtOpnd->hasOneUse()) {
3929  // ExtOpnd will be promoted.
3930  // All its uses, but Ext, will need to use a truncated value of the
3931  // promoted version.
3932  // Create the truncate now.
3933  Value *Trunc = TPT.createTrunc(Ext, ExtOpnd->getType());
3934  if (Instruction *ITrunc = dyn_cast<Instruction>(Trunc)) {
3935  // Insert it just after the definition.
3936  ITrunc->moveAfter(ExtOpnd);
3937  if (Truncs)
3938  Truncs->push_back(ITrunc);
3939  }
3940 
3941  TPT.replaceAllUsesWith(ExtOpnd, Trunc);
3942  // Restore the operand of Ext (which has been replaced by the previous call
3943  // to replaceAllUsesWith) to avoid creating a cycle trunc <-> sext.
3944  TPT.setOperand(Ext, 0, ExtOpnd);
3945  }
3946 
3947  // Get through the Instruction:
3948  // 1. Update its type.
3949  // 2. Replace the uses of Ext by Inst.
3950  // 3. Extend each operand that needs to be extended.
3951 
3952  // Remember the original type of the instruction before promotion.
3953  // This is useful to know that the high bits are sign extended bits.
3954  addPromotedInst(PromotedInsts, ExtOpnd, IsSExt);
3955  // Step #1.
3956  TPT.mutateType(ExtOpnd, Ext->getType());
3957  // Step #2.
3958  TPT.replaceAllUsesWith(Ext, ExtOpnd);
3959  // Step #3.
3960  Instruction *ExtForOpnd = Ext;
3961 
3962  LLVM_DEBUG(dbgs() << "Propagate Ext to operands\n");
3963  for (int OpIdx = 0, EndOpIdx = ExtOpnd->getNumOperands(); OpIdx != EndOpIdx;
3964  ++OpIdx) {
3965  LLVM_DEBUG(dbgs() << "Operand:\n" << *(ExtOpnd->getOperand(OpIdx)) << '\n');
3966  if (ExtOpnd->getOperand(OpIdx)->getType() == Ext->getType() ||
3967  !shouldExtOperand(ExtOpnd, OpIdx)) {
3968  LLVM_DEBUG(dbgs() << "No need to propagate\n");
3969  continue;
3970  }
3971  // Check if we can statically extend the operand.
3972  Value *Opnd = ExtOpnd->getOperand(OpIdx);
3973  if (const ConstantInt *Cst = dyn_cast<ConstantInt>(Opnd)) {
3974  LLVM_DEBUG(dbgs() << "Statically extend\n");
3975  unsigned BitWidth = Ext->getType()->getIntegerBitWidth();
3976  APInt CstVal = IsSExt ? Cst->getValue().sext(BitWidth)
3977  : Cst->getValue().zext(BitWidth);
3978  TPT.setOperand(ExtOpnd, OpIdx, ConstantInt::get(Ext->getType(), CstVal));
3979  continue;
3980  }
3981  // UndefValue are typed, so we have to statically sign extend them.
3982  if (isa<UndefValue>(Opnd)) {
3983  LLVM_DEBUG(dbgs() << "Statically extend\n");
3984  TPT.setOperand(ExtOpnd, OpIdx, UndefValue::get(Ext->getType()));
3985  continue;
3986  }
3987 
3988  // Otherwise we have to explicitly sign extend the operand.
3989  // Check if Ext was reused to extend an operand.
3990  if (!ExtForOpnd) {
3991  // If yes, create a new one.
3992  LLVM_DEBUG(dbgs() << "More operands to ext\n");
3993  Value *ValForExtOpnd = IsSExt ? TPT.createSExt(Ext, Opnd, Ext->getType())
3994  : TPT.createZExt(Ext, Opnd, Ext->getType());
3995  if (!isa<Instruction>(ValForExtOpnd)) {
3996  TPT.setOperand(ExtOpnd, OpIdx, ValForExtOpnd);
3997  continue;
3998  }
3999  ExtForOpnd = cast<Instruction>(ValForExtOpnd);
4000  }
4001  if (Exts)
4002  Exts->push_back(ExtForOpnd);
4003  TPT.setOperand(ExtForOpnd, 0, Opnd);
4004 
4005  // Move the sign extension before the insertion point.
4006  TPT.moveBefore(ExtForOpnd, ExtOpnd);
4007  TPT.setOperand(ExtOpnd, OpIdx, ExtForOpnd);
4008  CreatedInstsCost += !TLI.isExtFree(ExtForOpnd);
4009  // If more sext are required, new instructions will have to be created.
4010  ExtForOpnd = nullptr;
4011  }
4012  if (ExtForOpnd == Ext) {
4013  LLVM_DEBUG(dbgs() << "Extension is useless now\n");
4014  TPT.eraseInstruction(Ext);
4015  }
4016  return ExtOpnd;
4017 }
4018 
4019 /// Check whether or not promoting an instruction to a wider type is profitable.
4020 /// \p NewCost gives the cost of extension instructions created by the
4021 /// promotion.
4022 /// \p OldCost gives the cost of extension instructions before the promotion
4023 /// plus the number of instructions that have been
4024 /// matched in the addressing mode the promotion.
4025 /// \p PromotedOperand is the value that has been promoted.
4026 /// \return True if the promotion is profitable, false otherwise.
4027 bool AddressingModeMatcher::isPromotionProfitable(
4028  unsigned NewCost, unsigned OldCost, Value *PromotedOperand) const {
4029  LLVM_DEBUG(dbgs() << "OldCost: " << OldCost << "\tNewCost: " << NewCost
4030  << '\n');
4031  // The cost of the new extensions is greater than the cost of the
4032  // old extension plus what we folded.
4033  // This is not profitable.
4034  if (NewCost > OldCost)
4035  return false;
4036  if (NewCost < OldCost)
4037  return true;
4038  // The promotion is neutral but it may help folding the sign extension in
4039  // loads for instance.
4040  // Check that we did not create an illegal instruction.
4041  return isPromotedInstructionLegal(TLI, DL, PromotedOperand);
4042 }
4043 
4044 /// Given an instruction or constant expr, see if we can fold the operation
4045 /// into the addressing mode. If so, update the addressing mode and return
4046 /// true, otherwise return false without modifying AddrMode.
4047 /// If \p MovedAway is not NULL, it contains the information of whether or
4048 /// not AddrInst has to be folded into the addressing mode on success.
4049 /// If \p MovedAway == true, \p AddrInst will not be part of the addressing
4050 /// because it has been moved away.
4051 /// Thus AddrInst must not be added in the matched instructions.
4052 /// This state can happen when AddrInst is a sext, since it may be moved away.
4053 /// Therefore, AddrInst may not be valid when MovedAway is true and it must
4054 /// not be referenced anymore.
4055 bool AddressingModeMatcher::matchOperationAddr(User *AddrInst, unsigned Opcode,
4056  unsigned Depth,
4057  bool *MovedAway) {
4058  // Avoid exponential behavior on extremely deep expression trees.
4059  if (Depth >= 5) return false;
4060 
4061  // By default, all matched instructions stay in place.
4062  if (MovedAway)
4063  *MovedAway = false;
4064 
4065  switch (Opcode) {
4066  case Instruction::PtrToInt:
4067  // PtrToInt is always a noop, as we know that the int type is pointer sized.
4068  return matchAddr(AddrInst->getOperand(0), Depth);
4069  case Instruction::IntToPtr: {
4070  auto AS = AddrInst->getType()->getPointerAddressSpace();
4071  auto PtrTy = MVT::getIntegerVT(DL.getPointerSizeInBits(AS));
4072  // This inttoptr is a no-op if the integer type is pointer sized.
4073  if (TLI.getValueType(DL, AddrInst->getOperand(0)->getType()) == PtrTy)
4074  return matchAddr(AddrInst->getOperand(0), Depth);
4075  return false;
4076  }
4077  case Instruction::BitCast:
4078  // BitCast is always a noop, and we can handle it as long as it is
4079  // int->int or pointer->pointer (we don't want int<->fp or something).
4080  if (AddrInst->getOperand(0)->getType()->isIntOrPtrTy() &&
4081  // Don't touch identity bitcasts. These were probably put here by LSR,
4082  // and we don't want to mess around with them. Assume it knows what it
4083  // is doing.
4084  AddrInst->getOperand(0)->getType() != AddrInst->getType())
4085  return matchAddr(AddrInst->getOperand(0), Depth);
4086  return false;
4087  case Instruction::AddrSpaceCast: {
4088  unsigned SrcAS
4089  = AddrInst->getOperand(0)->getType()->getPointerAddressSpace();
4090  unsigned DestAS = AddrInst->getType()->getPointerAddressSpace();
4091  if (TLI.isNoopAddrSpaceCast(SrcAS, DestAS))
4092  return matchAddr(AddrInst->getOperand(0), Depth);
4093  return false;
4094  }
4095  case Instruction::Add: {
4096  // Check to see if we can merge in the RHS then the LHS. If so, we win.
4097  ExtAddrMode BackupAddrMode = AddrMode;
4098  unsigned OldSize = AddrModeInsts.size();
4099  // Start a transaction at this point.
4100  // The LHS may match but not the RHS.
4101  // Therefore, we need a higher level restoration point to undo partially
4102  // matched operation.
4103  TypePromotionTransaction::ConstRestorationPt LastKnownGood =
4104  TPT.getRestorationPoint();
4105 
4106  AddrMode.InBounds = false;
4107  if (matchAddr(AddrInst->getOperand(1), Depth+1) &&
4108  matchAddr(AddrInst->getOperand(0), Depth+1))
4109  return true;
4110 
4111  // Restore the old addr mode info.
4112  AddrMode = BackupAddrMode;
4113  AddrModeInsts.resize(OldSize);
4114  TPT.rollback(LastKnownGood);
4115 
4116  // Otherwise this was over-aggressive. Try merging in the LHS then the RHS.
4117  if (matchAddr(AddrInst->getOperand(0), Depth+1) &&
4118  matchAddr(AddrInst->getOperand(1), Depth+1))
4119  return true;
4120 
4121  // Otherwise we definitely can't merge the ADD in.
4122  AddrMode = BackupAddrMode;
4123  AddrModeInsts.resize(OldSize);
4124  TPT.rollback(LastKnownGood);
4125  break;
4126  }
4127  //case Instruction::Or:
4128  // TODO: We can handle "Or Val, Imm" iff this OR is equivalent to an ADD.
4129  //break;
4130  case Instruction::Mul:
4131  case Instruction::Shl: {
4132  // Can only handle X*C and X << C.
4133  AddrMode.InBounds = false;
4134  ConstantInt *RHS = dyn_cast<ConstantInt>(AddrInst->getOperand(1));
4135  if (!RHS || RHS->getBitWidth() > 64)
4136  return false;
4137  int64_t Scale = RHS->getSExtValue();
4138  if (Opcode == Instruction::Shl)
4139  Scale = 1LL << Scale;
4140 
4141  return matchScaledValue(AddrInst->getOperand(0), Scale, Depth);
4142  }
4143  case Instruction::GetElementPtr: {
4144  // Scan the GEP. We check it if it contains constant offsets and at most
4145  // one variable offset.
4146  int VariableOperand = -1;
4147  unsigned VariableScale = 0;
4148 
4149  int64_t ConstantOffset = 0;
4150  gep_type_iterator GTI = gep_type_begin(AddrInst);
4151  for (unsigned i = 1, e = AddrInst->getNumOperands(); i != e; ++i, ++GTI) {
4152  if (StructType *STy = GTI.getStructTypeOrNull()) {
4153  const StructLayout *SL = DL.getStructLayout(STy);
4154  unsigned Idx =
4155  cast<ConstantInt>(AddrInst->getOperand(i))->getZExtValue();
4156  ConstantOffset += SL->getElementOffset(Idx);
4157  } else {
4158  uint64_t TypeSize = DL.getTypeAllocSize(GTI.getIndexedType());
4159  if (ConstantInt *CI = dyn_cast<ConstantInt>(AddrInst->getOperand(i))) {
4160  const APInt &CVal = CI->getValue();
4161  if (CVal.getMinSignedBits() <= 64) {
4162  ConstantOffset += CVal.getSExtValue() * TypeSize;
4163  continue;
4164  }
4165  }
4166  if (TypeSize) { // Scales of zero don't do anything.
4167  // We only allow one variable index at the moment.
4168  if (VariableOperand != -1)
4169  return false;
4170 
4171  // Remember the variable index.
4172  VariableOperand = i;
4173  VariableScale = TypeSize;
4174  }
4175  }
4176  }
4177 
4178  // A common case is for the GEP to only do a constant offset. In this case,
4179  // just add it to the disp field and check validity.
4180  if (VariableOperand == -1) {
4181  AddrMode.BaseOffs += ConstantOffset;
4182  if (ConstantOffset == 0 ||
4183  TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace)) {
4184  // Check to see if we can fold the base pointer in too.
4185  if (matchAddr(AddrInst->getOperand(0), Depth+1)) {
4186  if (!cast<GEPOperator>(AddrInst)->isInBounds())
4187  AddrMode.InBounds = false;
4188  return true;
4189  }
4190  } else if (EnableGEPOffsetSplit && isa<GetElementPtrInst>(AddrInst) &&
4191  TLI.shouldConsiderGEPOffsetSplit() && Depth == 0 &&
4192  ConstantOffset > 0) {
4193  // Record GEPs with non-zero offsets as candidates for splitting in the
4194  // event that the offset cannot fit into the r+i addressing mode.
4195  // Simple and common case that only one GEP is used in calculating the
4196  // address for the memory access.
4197  Value *Base = AddrInst->getOperand(0);
4198  auto *BaseI = dyn_cast<Instruction>(Base);
4199  auto *GEP = cast<GetElementPtrInst>(AddrInst);
4200  if (isa<Argument>(Base) || isa<GlobalValue>(Base) ||
4201  (BaseI && !isa<CastInst>(BaseI) &&
4202  !isa<GetElementPtrInst>(BaseI))) {
4203  // Make sure the parent block allows inserting non-PHI instructions
4204  // before the terminator.
4205  BasicBlock *Parent =
4206  BaseI ? BaseI->getParent() : &GEP->getFunction()->getEntryBlock();
4207  if (!Parent->getTerminator()->isEHPad())
4208  LargeOffsetGEP = std::make_pair(GEP, ConstantOffset);
4209  }
4210  }
4211  AddrMode.BaseOffs -= ConstantOffset;
4212  return false;
4213  }
4214 
4215  // Save the valid addressing mode in case we can't match.
4216  ExtAddrMode BackupAddrMode = AddrMode;
4217  unsigned OldSize = AddrModeInsts.size();
4218 
4219  // See if the scale and offset amount is valid for this target.
4220  AddrMode.BaseOffs += ConstantOffset;
4221  if (!cast<GEPOperator>(AddrInst)->isInBounds())
4222  AddrMode.InBounds = false;
4223 
4224  // Match the base operand of the GEP.
4225  if (!matchAddr(AddrInst->getOperand(0), Depth+1)) {
4226  // If it couldn't be matched, just stuff the value in a register.
4227  if (AddrMode.HasBaseReg) {
4228  AddrMode = BackupAddrMode;
4229  AddrModeInsts.resize(OldSize);
4230  return false;
4231  }
4232  AddrMode.HasBaseReg = true;
4233  AddrMode.BaseReg = AddrInst->getOperand(0);
4234  }
4235 
4236  // Match the remaining variable portion of the GEP.
4237  if (!matchScaledValue(AddrInst->getOperand(VariableOperand), VariableScale,
4238  Depth)) {
4239  // If it couldn't be matched, try stuffing the base into a register
4240  // instead of matching it, and retrying the match of the scale.
4241  AddrMode = BackupAddrMode;
4242  AddrModeInsts.resize(OldSize);
4243  if (AddrMode.HasBaseReg)
4244  return false;
4245  AddrMode.HasBaseReg = true;
4246  AddrMode.BaseReg = AddrInst->getOperand(0);
4247  AddrMode.BaseOffs += ConstantOffset;
4248  if (!matchScaledValue(AddrInst->getOperand(VariableOperand),
4249  VariableScale, Depth)) {
4250  // If even that didn't work, bail.
4251  AddrMode = BackupAddrMode;
4252  AddrModeInsts.resize(OldSize);
4253  return false;
4254  }
4255  }
4256 
4257  return true;
4258  }
4259  case Instruction::SExt:
4260  case Instruction::ZExt: {
4261  Instruction *Ext = dyn_cast<Instruction>(AddrInst);
4262  if (!Ext)
4263  return false;
4264 
4265  // Try to move this ext out of the way of the addressing mode.
4266  // Ask for a method for doing so.
4267  TypePromotionHelper::Action TPH =
4268  TypePromotionHelper::getAction(Ext, InsertedInsts, TLI, PromotedInsts);
4269  if (!TPH)
4270  return false;
4271 
4272  TypePromotionTransaction::ConstRestorationPt LastKnownGood =
4273  TPT.getRestorationPoint();
4274  unsigned CreatedInstsCost = 0;
4275  unsigned ExtCost = !TLI.isExtFree(Ext);
4276  Value *PromotedOperand =
4277  TPH(Ext, TPT, PromotedInsts, CreatedInstsCost, nullptr, nullptr, TLI);
4278  // SExt has been moved away.
4279  // Thus either it will be rematched later in the recursive calls or it is
4280  // gone. Anyway, we must not fold it into the addressing mode at this point.
4281  // E.g.,
4282  // op = add opnd, 1
4283  // idx = ext op
4284  // addr = gep base, idx
4285  // is now:
4286  // promotedOpnd = ext opnd <- no match here
4287  // op = promoted_add promotedOpnd, 1 <- match (later in recursive calls)
4288  // addr = gep base, op <- match
4289  if (MovedAway)
4290  *MovedAway = true;
4291 
4292  assert(PromotedOperand &&
4293  "TypePromotionHelper should have filtered out those cases");
4294 
4295  ExtAddrMode BackupAddrMode = AddrMode;
4296  unsigned OldSize = AddrModeInsts.size();
4297 
4298  if (!matchAddr(PromotedOperand, Depth) ||
4299  // The total of the new cost is equal to the cost of the created
4300  // instructions.
4301  // The total of the old cost is equal to the cost of the extension plus
4302  // what we have saved in the addressing mode.
4303  !isPromotionProfitable(CreatedInstsCost,
4304  ExtCost + (AddrModeInsts.size() - OldSize),
4305  PromotedOperand)) {
4306  AddrMode = BackupAddrMode;
4307  AddrModeInsts.resize(OldSize);
4308  LLVM_DEBUG(dbgs() << "Sign extension does not pay off: rollback\n");
4309  TPT.rollback(LastKnownGood);
4310  return false;
4311  }
4312  return true;
4313  }
4314  }
4315  return false;
4316 }
4317 
4318 /// If we can, try to add the value of 'Addr' into the current addressing mode.
4319 /// If Addr can't be added to AddrMode this returns false and leaves AddrMode
4320 /// unmodified. This assumes that Addr is either a pointer type or intptr_t
4321 /// for the target.
4322 ///
4323 bool AddressingModeMatcher::matchAddr(Value *Addr, unsigned Depth) {
4324  // Start a transaction at this point that we will rollback if the matching
4325  // fails.
4326  TypePromotionTransaction::ConstRestorationPt LastKnownGood =
4327  TPT.getRestorationPoint();
4328  if (ConstantInt *CI = dyn_cast<ConstantInt>(Addr)) {
4329  // Fold in immediates if legal for the target.
4330  AddrMode.BaseOffs += CI->getSExtValue();
4331  if (TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace))
4332  return true;
4333  AddrMode.BaseOffs -= CI->getSExtValue();
4334  } else if (GlobalValue *GV = dyn_cast<GlobalValue>(Addr)) {
4335  // If this is a global variable, try to fold it into the addressing mode.
4336  if (!AddrMode.BaseGV) {
4337  AddrMode.BaseGV = GV;
4338  if (TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace))
4339  return true;
4340  AddrMode.BaseGV = nullptr;
4341  }
4342  } else if (Instruction *I = dyn_cast<Instruction>(Addr)) {
4343  ExtAddrMode BackupAddrMode = AddrMode;
4344  unsigned OldSize = AddrModeInsts.size();
4345 
4346  // Check to see if it is possible to fold this operation.
4347  bool MovedAway = false;
4348  if (matchOperationAddr(I, I->getOpcode(), Depth, &MovedAway)) {
4349  // This instruction may have been moved away. If so, there is nothing
4350  // to check here.
4351  if (MovedAway)
4352  return true;
4353  // Okay, it's possible to fold this. Check to see if it is actually
4354  // *profitable* to do so. We use a simple cost model to avoid increasing
4355  // register pressure too much.
4356  if (I->hasOneUse() ||
4357  isProfitableToFoldIntoAddressingMode(I, BackupAddrMode, AddrMode)) {
4358  AddrModeInsts.push_back(I);
4359  return true;
4360  }
4361 
4362  // It isn't profitable to do this, roll back.
4363  //cerr << "NOT FOLDING: " << *I;
4364  AddrMode = BackupAddrMode;
4365  AddrModeInsts.resize(OldSize);
4366  TPT.rollback(LastKnownGood);
4367  }
4368  } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Addr)) {
4369  if (matchOperationAddr(CE, CE->getOpcode(), Depth))
4370  return true;
4371  TPT.rollback(LastKnownGood);
4372  } else if (isa<ConstantPointerNull>(Addr)) {
4373  // Null pointer gets folded without affecting the addressing mode.
4374  return true;
4375  }
4376 
4377  // Worse case, the target should support [reg] addressing modes. :)
4378  if (!AddrMode.HasBaseReg) {
4379  AddrMode.HasBaseReg = true;
4380  AddrMode.BaseReg = Addr;
4381  // Still check for legality in case the target supports [imm] but not [i+r].
4382  if (TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace))
4383  return true;
4384  AddrMode.HasBaseReg = false;
4385  AddrMode.BaseReg = nullptr;
4386  }
4387 
4388  // If the base register is already taken, see if we can do [r+r].
4389  if (AddrMode.Scale == 0) {
4390  AddrMode.Scale = 1;
4391  AddrMode.ScaledReg = Addr;
4392  if (TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace))
4393  return true;
4394  AddrMode.Scale = 0;
4395  AddrMode.ScaledReg = nullptr;
4396  }
4397  // Couldn't match.
4398  TPT.rollback(LastKnownGood);
4399  return false;
4400 }
4401 
4402 /// Check to see if all uses of OpVal by the specified inline asm call are due
4403 /// to memory operands. If so, return true, otherwise return false.
4404 static bool IsOperandAMemoryOperand(CallInst *CI, InlineAsm *IA, Value *OpVal,
4405  const TargetLowering &TLI,
4406  const TargetRegisterInfo &TRI) {
4407  const Function *F = CI->getFunction();
4408  TargetLowering::AsmOperandInfoVector TargetConstraints =
4410  ImmutableCallSite(CI));
4411 
4412  for (unsigned i = 0, e = TargetConstraints.size(); i != e; ++i) {
4413  TargetLowering::AsmOperandInfo &OpInfo = TargetConstraints[i];
4414 
4415  // Compute the constraint code and ConstraintType to use.
4416  TLI.ComputeConstraintToUse(OpInfo, SDValue());
4417 
4418  // If this asm operand is our Value*, and if it isn't an indirect memory
4419  // operand, we can't fold it!
4420  if (OpInfo.CallOperandVal == OpVal &&
4422  !OpInfo.isIndirect))
4423  return false;
4424  }
4425 
4426  return true;
4427 }
4428 
4429 // Max number of memory uses to look at before aborting the search to conserve
4430 // compile time.
4431 static constexpr int MaxMemoryUsesToScan = 20;
4432 
4433 /// Recursively walk all the uses of I until we find a memory use.
4434 /// If we find an obviously non-foldable instruction, return true.
4435 /// Add the ultimately found memory instructions to MemoryUses.
4436 static bool FindAllMemoryUses(
4437  Instruction *I,
4438  SmallVectorImpl<std::pair<Instruction *, unsigned>> &MemoryUses,
4439  SmallPtrSetImpl<Instruction *> &ConsideredInsts, const TargetLowering &TLI,
4440  const TargetRegisterInfo &TRI, int SeenInsts = 0) {
4441  // If we already considered this instruction, we're done.
4442  if (!ConsideredInsts.insert(I).second)
4443  return false;
4444 
4445  // If this is an obviously unfoldable instruction, bail out.
4446  if (!MightBeFoldableInst(I))
4447  return true;
4448 
4449  const bool OptSize = I->getFunction()->hasOptSize();
4450 
4451  // Loop over all the uses, recursively processing them.
4452  for (Use &U : I->uses()) {
4453  // Conservatively return true if we're seeing a large number or a deep chain
4454  // of users. This avoids excessive compilation times in pathological cases.
4455  if (SeenInsts++ >= MaxMemoryUsesToScan)
4456  return true;
4457 
4458  Instruction *UserI = cast<Instruction>(U.getUser());
4459  if (LoadInst *LI = dyn_cast<LoadInst>(UserI)) {
4460  MemoryUses.push_back(std::make_pair(LI, U.getOperandNo()));
4461  continue;
4462  }
4463 
4464  if (StoreInst *SI = dyn_cast<StoreInst>(UserI)) {
4465  unsigned opNo = U.getOperandNo();
4466  if (opNo != StoreInst::getPointerOperandIndex())
4467  return true; // Storing addr, not into addr.
4468  MemoryUses.push_back(std::make_pair(SI, opNo));
4469  continue;
4470  }
4471 
4472  if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(UserI)) {
4473  unsigned opNo = U.getOperandNo();
4475  return true; // Storing addr, not into addr.
4476  MemoryUses.push_back(std::make_pair(RMW, opNo));
4477  continue;
4478  }
4479 
4480  if (AtomicCmpXchgInst *CmpX = dyn_cast<AtomicCmpXchgInst>(UserI)) {
4481  unsigned opNo = U.getOperandNo();
4483  return true; // Storing addr, not into addr.
4484  MemoryUses.push_back(std::make_pair(CmpX, opNo));
4485  continue;
4486  }
4487 
4488  if (CallInst *CI = dyn_cast<CallInst>(UserI)) {
4489  // If this is a cold call, we can sink the addressing calculation into
4490  // the cold path. See optimizeCallInst
4491  if (!OptSize && CI->hasFnAttr(Attribute::Cold))
4492  continue;
4493 
4495  if (!IA) return true;
4496 
4497  // If this is a memory operand, we're cool, otherwise bail out.
4498  if (!IsOperandAMemoryOperand(CI, IA, I, TLI, TRI))
4499  return true;
4500  continue;
4501  }
4502 
4503  if (FindAllMemoryUses(UserI, MemoryUses, ConsideredInsts, TLI, TRI,
4504  SeenInsts))
4505  return true;
4506  }
4507 
4508  return false;
4509 }
4510 
4511 /// Return true if Val is already known to be live at the use site that we're
4512 /// folding it into. If so, there is no cost to include it in the addressing
4513 /// mode. KnownLive1 and KnownLive2 are two values that we know are live at the
4514 /// instruction already.
4515 bool AddressingModeMatcher::valueAlreadyLiveAtInst(Value *Val,Value *KnownLive1,
4516  Value *KnownLive2) {
4517  // If Val is either of the known-live values, we know it is live!
4518  if (Val == nullptr || Val == KnownLive1 || Val == KnownLive2)
4519  return true;
4520 
4521  // All values other than instructions and arguments (e.g. constants) are live.
4522  if (!isa<Instruction>(Val) && !isa<Argument>(Val)) return true;
4523 
4524  // If Val is a constant sized alloca in the entry block, it is live, this is
4525  // true because it is just a reference to the stack/frame pointer, which is
4526  // live for the whole function.
4527  if (AllocaInst *AI = dyn_cast<AllocaInst>(Val))
4528  if (AI->isStaticAlloca())
4529  return true;
4530 
4531  // Check to see if this value is already used in the memory instruction's
4532  // block. If so, it's already live into the block at the very least, so we
4533  // can reasonably fold it.
4534  return Val->isUsedInBasicBlock(MemoryInst->getParent());
4535 }
4536 
4537 /// It is possible for the addressing mode of the machine to fold the specified
4538 /// instruction into a load or store that ultimately uses it.
4539 /// However, the specified instruction has multiple uses.
4540 /// Given this, it may actually increase register pressure to fold it
4541 /// into the load. For example, consider this code:
4542 ///
4543 /// X = ...
4544 /// Y = X+1
4545 /// use(Y) -> nonload/store
4546 /// Z = Y+1
4547 /// load Z
4548 ///
4549 /// In this case, Y has multiple uses, and can be folded into the load of Z
4550 /// (yielding load [X+2]). However, doing this will cause both "X" and "X+1" to
4551 /// be live at the use(Y) line. If we don't fold Y into load Z, we use one
4552 /// fewer register. Since Y can't be folded into "use(Y)" we don't increase the
4553 /// number of computations either.
4554 ///
4555 /// Note that this (like most of CodeGenPrepare) is just a rough heuristic. If
4556 /// X was live across 'load Z' for other reasons, we actually *would* want to
4557 /// fold the addressing mode in the Z case. This would make Y die earlier.
4558 bool AddressingModeMatcher::
4559 isProfitableToFoldIntoAddressingMode(Instruction *I, ExtAddrMode &AMBefore,
4560  ExtAddrMode &AMAfter) {
4561  if (IgnoreProfitability) return true;
4562 
4563  // AMBefore is the addressing mode before this instruction was folded into it,
4564  // and AMAfter is the addressing mode after the instruction was folded. Get
4565  // the set of registers referenced by AMAfter and subtract out those
4566  // referenced by AMBefore: this is the set of values which folding in this
4567  // address extends the lifetime of.
4568  //
4569  // Note that there are only two potential values being referenced here,
4570  // BaseReg and ScaleReg (global addresses are always available, as are any
4571  // folded immediates).
4572  Value *BaseReg = AMAfter.BaseReg, *ScaledReg = AMAfter.ScaledReg;
4573 
4574  // If the BaseReg or ScaledReg was referenced by the previous addrmode, their
4575  // lifetime wasn't extended by adding this instruction.
4576  if (valueAlreadyLiveAtInst(BaseReg, AMBefore.BaseReg, AMBefore.ScaledReg))
4577  BaseReg = nullptr;
4578  if (valueAlreadyLiveAtInst(ScaledReg, AMBefore.BaseReg, AMBefore.ScaledReg))
4579  ScaledReg = nullptr;
4580 
4581  // If folding this instruction (and it's subexprs) didn't extend any live
4582  // ranges, we're ok with it.
4583  if (!BaseReg && !ScaledReg)
4584  return true;
4585 
4586  // If all uses of this instruction can have the address mode sunk into them,
4587  // we can remove the addressing mode and effectively trade one live register
4588  // for another (at worst.) In this context, folding an addressing mode into
4589  // the use is just a particularly nice way of sinking it.
4591  SmallPtrSet<Instruction*, 16> ConsideredInsts;
4592  if (FindAllMemoryUses(I, MemoryUses, ConsideredInsts, TLI, TRI))
4593  return false; // Has a non-memory, non-foldable use!
4594 
4595  // Now that we know that all uses of this instruction are part of a chain of
4596  // computation involving only operations that could theoretically be folded
4597  // into a memory use, loop over each of these memory operation uses and see
4598  // if they could *actually* fold the instruction. The assumption is that
4599  // addressing modes are cheap and that duplicating the computation involved
4600  // many times is worthwhile, even on a fastpath. For sinking candidates
4601  // (i.e. cold call sites), this serves as a way to prevent excessive code
4602  // growth since most architectures have some reasonable small and fast way to
4603  // compute an effective address. (i.e LEA on x86)
4604  SmallVector<Instruction*, 32> MatchedAddrModeInsts;
4605  for (unsigned i = 0, e = MemoryUses.size(); i != e; ++i) {
4606  Instruction *User = MemoryUses[i].first;
4607  unsigned OpNo = MemoryUses[i].second;
4608 
4609  // Get the access type of this use. If the use isn't a pointer, we don't
4610  // know what it accesses.
4611  Value *Address = User->getOperand(OpNo);
4612  PointerType *AddrTy = dyn_cast<PointerType>(Address->getType());
4613  if (!AddrTy)
4614  return false;
4615  Type *AddressAccessTy = AddrTy->getElementType();
4616  unsigned AS = AddrTy->getAddressSpace();
4617 
4618  // Do a match against the root of this address, ignoring profitability. This
4619  // will tell us if the addressing mode for the memory operation will
4620  // *actually* cover the shared instruction.
4621  ExtAddrMode Result;
4622  std::pair<AssertingVH<GetElementPtrInst>, int64_t> LargeOffsetGEP(nullptr,
4623  0);
4624  TypePromotionTransaction::ConstRestorationPt LastKnownGood =
4625  TPT.getRestorationPoint();
4626  AddressingModeMatcher Matcher(
4627  MatchedAddrModeInsts, TLI, TRI, AddressAccessTy, AS, MemoryInst, Result,
4628  InsertedInsts, PromotedInsts, TPT, LargeOffsetGEP);
4629  Matcher.IgnoreProfitability = true;
4630  bool Success = Matcher.matchAddr(Address, 0);
4631  (void)Success; assert(Success && "Couldn't select *anything*?");
4632 
4633  // The match was to check the profitability, the changes made are not
4634  // part of the original matcher. Therefore, they should be dropped
4635  // otherwise the original matcher will not present the right state.
4636  TPT.rollback(LastKnownGood);
4637 
4638  // If the match didn't cover I, then it won't be shared by it.
4639  if (!is_contained(MatchedAddrModeInsts, I))
4640  return false;
4641 
4642  MatchedAddrModeInsts.clear();
4643  }
4644 
4645  return true;
4646 }
4647 
4648 /// Return true if the specified values are defined in a
4649 /// different basic block than BB.
4650 static bool IsNonLocalValue(Value *V, BasicBlock *BB) {
4651  if (Instruction *I = dyn_cast<Instruction>(V))
4652  return I->getParent() != BB;
4653  return false;
4654 }
4655 
4656 /// Sink addressing mode computation immediate before MemoryInst if doing so
4657 /// can be done without increasing register pressure. The need for the
4658 /// register pressure constraint means this can end up being an all or nothing
4659 /// decision for all uses of the same addressing computation.
4660 ///
4661 /// Load and Store Instructions often have addressing modes that can do
4662 /// significant amounts of computation. As such, instruction selection will try
4663 /// to get the load or store to do as much computation as possible for the
4664 /// program. The problem is that isel can only see within a single block. As
4665 /// such, we sink as much legal addressing mode work into the block as possible.
4666 ///
4667 /// This method is used to optimize both load/store and inline asms with memory
4668 /// operands. It's also used to sink addressing computations feeding into cold
4669 /// call sites into their (cold) basic block.
4670 ///
4671 /// The motivation for handling sinking into cold blocks is that doing so can
4672 /// both enable other address mode sinking (by satisfying the register pressure
4673 /// constraint above), and reduce register pressure globally (by removing the
4674 /// addressing mode computation from the fast path entirely.).
4675 bool CodeGenPrepare::optimizeMemoryInst(Instruction *MemoryInst, Value *Addr,
4676  Type *AccessTy, unsigned AddrSpace) {
4677  Value *Repl = Addr;
4678 
4679  // Try to collapse single-value PHI nodes. This is necessary to undo
4680  // unprofitable PRE transformations.
4681  SmallVector<Value*, 8> worklist;
4682  SmallPtrSet<Value*, 16> Visited;
4683  worklist.push_back(Addr);
4684 
4685  // Use a worklist to iteratively look through PHI and select nodes, and
4686  // ensure that the addressing mode obtained from the non-PHI/select roots of
4687  // the graph are compatible.
4688  bool PhiOrSelectSeen = false;
4689  SmallVector<Instruction*, 16> AddrModeInsts;
4690  const SimplifyQuery SQ(*DL, TLInfo);
4691  AddressingModeCombiner AddrModes(SQ, Addr);
4692  TypePromotionTransaction TPT(RemovedInsts);
4693  TypePromotionTransaction::ConstRestorationPt LastKnownGood =
4694  TPT.getRestorationPoint();
4695  while (!worklist.empty()) {
4696  Value *V = worklist.back();
4697  worklist.pop_back();
4698 
4699  // We allow traversing cyclic Phi nodes.
4700  // In case of success after this loop we ensure that traversing through
4701  // Phi nodes ends up with all cases to compute address of the form
4702  // BaseGV + Base + Scale * Index + Offset
4703  // where Scale and Offset are constans and BaseGV, Base and Index
4704  // are exactly the same Values in all cases.
4705  // It means that BaseGV, Scale and Offset dominate our memory instruction
4706  // and have the same value as they had in address computation represented
4707  // as Phi. So we can safely sink address computation to memory instruction.
4708  if (!Visited.insert(V).second)
4709  continue;
4710 
4711  // For a PHI node, push all of its incoming values.
4712  if (PHINode *P = dyn_cast<PHINode>(V)) {
4713  for (Value *IncValue : P->incoming_values())
4714  worklist.push_back(IncValue);
4715  PhiOrSelectSeen = true;
4716  continue;
4717  }
4718  // Similar for select.
4719  if (SelectInst *SI = dyn_cast<SelectInst>(V)) {
4720  worklist.push_back(SI->getFalseValue());
4721  worklist.push_back(SI->getTrueValue());
4722  PhiOrSelectSeen = true;
4723  continue;
4724  }
4725 
4726  // For non-PHIs, determine the addressing mode being computed. Note that
4727  // the result may differ depending on what other uses our candidate
4728  // addressing instructions might have.
4729  AddrModeInsts.clear();
4730  std::pair<AssertingVH<GetElementPtrInst>, int64_t> LargeOffsetGEP(nullptr,
4731  0);
4732  ExtAddrMode NewAddrMode = AddressingModeMatcher::Match(
4733  V, AccessTy, AddrSpace, MemoryInst, AddrModeInsts, *TLI, *TRI,
4734  InsertedInsts, PromotedInsts, TPT, LargeOffsetGEP);
4735 
4736  GetElementPtrInst *GEP = LargeOffsetGEP.first;
4737  if (GEP && !NewGEPBases.count(GEP)) {
4738  // If splitting the underlying data structure can reduce the offset of a
4739  // GEP, collect the GEP. Skip the GEPs that are the new bases of
4740  // previously split data structures.
4741  LargeOffsetGEPMap[GEP->getPointerOperand()].push_back(LargeOffsetGEP);
4742  if (LargeOffsetGEPID.find(GEP) == LargeOffsetGEPID.end())
4743  LargeOffsetGEPID[GEP] = LargeOffsetGEPID.size();
4744  }
4745 
4746  NewAddrMode.OriginalValue = V;
4747  if (!AddrModes.addNewAddrMode(NewAddrMode))
4748  break;
4749  }
4750 
4751  // Try to combine the AddrModes we've collected. If we couldn't collect any,
4752  // or we have multiple but either couldn't combine them or combining them
4753  // wouldn't do anything useful, bail out now.
4754  if (!AddrModes.combineAddrModes()) {
4755  TPT.rollback(LastKnownGood);
4756  return false;
4757  }
4758  TPT.commit();
4759 
4760  // Get the combined AddrMode (or the only AddrMode, if we only had one).
4761  ExtAddrMode AddrMode = AddrModes.getAddrMode();
4762 
4763  // If all the instructions matched are already in this BB, don't do anything.
4764  // If we saw a Phi node then it is not local definitely, and if we saw a select
4765  // then we want to push the address calculation past it even if it's already
4766  // in this BB.
4767  if (!PhiOrSelectSeen && none_of(AddrModeInsts, [&](Value *V) {
4768  return IsNonLocalValue(V, MemoryInst->getParent());
4769  })) {
4770  LLVM_DEBUG(dbgs() << "CGP: Found local addrmode: " << AddrMode
4771  << "\n");
4772  return false;
4773  }
4774 
4775  // Insert this computation right after this user. Since our caller is
4776  // scanning from the top of the BB to the bottom, reuse of the expr are
4777  // guaranteed to happen later.
4778  IRBuilder<> Builder(MemoryInst);
4779 
4780  // Now that we determined the addressing expression we want to use and know
4781  // that we have to sink it into this block. Check to see if we have already
4782  // done this for some other load/store instr in this block. If so, reuse
4783  // the computation. Before attempting reuse, check if the address is valid
4784  // as it may have been erased.
4785 
4786  WeakTrackingVH SunkAddrVH = SunkAddrs[Addr];
4787 
4788  Value * SunkAddr = SunkAddrVH.pointsToAliveValue() ? SunkAddrVH : nullptr;
4789  if (SunkAddr) {
4790  LLVM_DEBUG(dbgs() << "CGP: Reusing nonlocal addrmode: " << AddrMode
4791  << " for " << *MemoryInst << "\n");
4792  if (SunkAddr->getType() != Addr->getType())
4793  SunkAddr = Builder.CreatePointerCast(SunkAddr, Addr->getType());
4794  } else if (AddrSinkUsingGEPs || (!AddrSinkUsingGEPs.getNumOccurrences() &&
4795  TM && SubtargetInfo->addrSinkUsingGEPs())) {
4796  // By default, we use the GEP-based method when AA is used later. This
4797  // prevents new inttoptr/ptrtoint pairs from degrading AA capabilities.
4798  LLVM_DEBUG(dbgs() << "CGP: SINKING nonlocal addrmode: " << AddrMode
4799  << " for " << *MemoryInst << "\n");
4800  Type *IntPtrTy = DL->getIntPtrType(Addr->getType());
4801  Value *ResultPtr = nullptr, *ResultIndex = nullptr;
4802 
4803  // First, find the pointer.
4804  if (AddrMode.BaseReg && AddrMode.BaseReg->getType()->isPointerTy()) {
4805  ResultPtr = AddrMode.BaseReg;
4806  AddrMode.BaseReg = nullptr;
4807  }
4808 
4809  if (AddrMode.Scale && AddrMode.ScaledReg->getType()->isPointerTy()) {
4810  // We can't add more than one pointer together, nor can we scale a
4811  // pointer (both of which seem meaningless).
4812  if (ResultPtr || AddrMode.Scale != 1)
4813  return false;
4814 
4815  ResultPtr = AddrMode.ScaledReg;
4816  AddrMode.Scale = 0;
4817  }
4818 
4819  // It is only safe to sign extend the BaseReg if we know that the math
4820  // required to create it did not overflow before we extend it. Since
4821  // the original IR value was tossed in favor of a constant back when
4822  // the AddrMode was created we need to bail out gracefully if widths
4823  // do not match instead of extending it.
4824  //
4825  // (See below for code to add the scale.)
4826  if (AddrMode.Scale) {
4827  Type *ScaledRegTy = AddrMode.ScaledReg->getType();
4828  if (cast<IntegerType>(IntPtrTy)->getBitWidth() >
4829  cast<IntegerType>(ScaledRegTy)->getBitWidth())
4830  return false;
4831  }
4832 
4833  if (AddrMode.BaseGV) {
4834  if (ResultPtr)
4835  return false;
4836 
4837  ResultPtr = AddrMode.BaseGV;
4838  }
4839 
4840  // If the real base value actually came from an inttoptr, then the matcher
4841  // will look through it and provide only the integer value. In that case,
4842  // use it here.
4843  if (!DL->isNonIntegralPointerType(Addr->getType())) {
4844  if (!ResultPtr && AddrMode.BaseReg) {
4845  ResultPtr = Builder.CreateIntToPtr(AddrMode.BaseReg, Addr->getType(),
4846  "sunkaddr");
4847  AddrMode.BaseReg = nullptr;
4848  } else if (!ResultPtr && AddrMode.Scale == 1) {
4849  ResultPtr = Builder.CreateIntToPtr(AddrMode.ScaledReg, Addr->getType(),
4850  "sunkaddr");
4851  AddrMode.Scale = 0;
4852  }
4853  }
4854 
4855  if (!ResultPtr &&
4856  !AddrMode.BaseReg && !AddrMode.Scale && !AddrMode.BaseOffs) {
4857  SunkAddr = Constant::getNullValue(Addr->getType());
4858  } else if (!ResultPtr) {
4859  return false;
4860  } else {
4861  Type *I8PtrTy =
4862  Builder.getInt8PtrTy(Addr->getType()->getPointerAddressSpace());
4863  Type *I8Ty = Builder.getInt8Ty();
4864 
4865  // Start with the base register. Do this first so that subsequent address
4866  // matching finds it last, which will prevent it from trying to match it
4867  // as the scaled value in case it happens to be a mul. That would be
4868  // problematic if we've sunk a different mul for the scale, because then
4869  // we'd end up sinking both muls.
4870  if (AddrMode.BaseReg) {
4871  Value *V = AddrMode.BaseReg;
4872  if (V->getType() != IntPtrTy)
4873  V = Builder.CreateIntCast(V, IntPtrTy, /*isSigned=*/true, "sunkaddr");
4874 
4875  ResultIndex = V;
4876  }
4877 
4878  // Add the scale value.
4879  if (AddrMode.Scale) {
4880  Value *V = AddrMode.ScaledReg;
4881  if (V->getType() == IntPtrTy) {
4882  // done.
4883  } else {
4884  assert(cast<IntegerType>(IntPtrTy)->getBitWidth() <
4885  cast<IntegerType>(V->getType())->getBitWidth() &&
4886  "We can't transform if ScaledReg is too narrow");
4887  V = Builder.CreateTrunc(V, IntPtrTy, "sunkaddr");
4888  }
4889 
4890  if (AddrMode.Scale != 1)
4891  V = Builder.CreateMul(V, ConstantInt::get(IntPtrTy, AddrMode.Scale),
4892  "sunkaddr");
4893  if (ResultIndex)
4894  ResultIndex = Builder.CreateAdd(ResultIndex, V, "sunkaddr");
4895  else
4896  ResultIndex = V;
4897  }
4898 
4899  // Add in the Base Offset if present.
4900  if (AddrMode.BaseOffs) {
4901  Value *V = ConstantInt::get(IntPtrTy, AddrMode.BaseOffs);
4902  if (ResultIndex) {
4903  // We need to add this separately from the scale above to help with
4904  // SDAG consecutive load/store merging.
4905  if (ResultPtr->getType() != I8PtrTy)
4906  ResultPtr = Builder.CreatePointerCast(ResultPtr, I8PtrTy);
4907  ResultPtr =
4908  AddrMode.InBounds
4909  ? Builder.CreateInBoundsGEP(I8Ty, ResultPtr, ResultIndex,
4910  "sunkaddr")
4911  : Builder.CreateGEP(I8Ty, ResultPtr, ResultIndex, "sunkaddr");
4912  }
4913 
4914  ResultIndex = V;
4915  }
4916 
4917  if (!ResultIndex) {
4918  SunkAddr = ResultPtr;
4919  } else {
4920  if (ResultPtr->getType() != I8PtrTy)
4921  ResultPtr = Builder.CreatePointerCast(ResultPtr, I8PtrTy);
4922  SunkAddr =
4923  AddrMode.InBounds
4924  ? Builder.CreateInBoundsGEP(I8Ty, ResultPtr, ResultIndex,
4925  "sunkaddr")
4926  : Builder.CreateGEP(I8Ty, ResultPtr, ResultIndex, "sunkaddr");
4927  }
4928 
4929  if (SunkAddr->getType() != Addr->getType())
4930  SunkAddr = Builder.CreatePointerCast(SunkAddr, Addr->getType());
4931  }
4932  } else {
4933  // We'd require a ptrtoint/inttoptr down the line, which we can't do for
4934  // non-integral pointers, so in that case bail out now.
4935  Type *BaseTy = AddrMode.BaseReg ? AddrMode.BaseReg->getType() : nullptr;
4936  Type *ScaleTy = AddrMode.Scale ? AddrMode.ScaledReg->getType() : nullptr;
4937  PointerType *BasePtrTy = dyn_cast_or_null<PointerType>(BaseTy);
4938  PointerType *ScalePtrTy = dyn_cast_or_null<PointerType>(ScaleTy);
4939  if (DL->isNonIntegralPointerType(Addr->getType()) ||
4940  (BasePtrTy && DL->isNonIntegralPointerType(BasePtrTy)) ||
4941  (ScalePtrTy && DL->isNonIntegralPointerType(ScalePtrTy)) ||
4942  (AddrMode.BaseGV &&
4943  DL->isNonIntegralPointerType(AddrMode.BaseGV->getType())))
4944  return false;
4945 
4946  LLVM_DEBUG(dbgs() << "CGP: SINKING nonlocal addrmode: " << AddrMode
4947  << " for " << *MemoryInst << "\n");
4948  Type *IntPtrTy = DL->getIntPtrType(Addr->getType());
4949  Value *Result = nullptr;
4950 
4951  // Start with the base register. Do this first so that subsequent address
4952  // matching finds it last, which will prevent it from trying to match it
4953  // as the scaled value in case it happens to be a mul. That would be
4954  // problematic if we've sunk a different mul for the scale, because then
4955  // we'd end up sinking both muls.
4956  if (AddrMode.BaseReg) {
4957  Value *V = AddrMode.BaseReg;
4958  if (V->getType()->isPointerTy())
4959  V = Builder.CreatePtrToInt(V, IntPtrTy, "sunkaddr");
4960  if (V->getType() != IntPtrTy)
4961  V = Builder.CreateIntCast(V, IntPtrTy, /*isSigned=*/true, "sunkaddr");
4962  Result = V;
4963  }
4964 
4965  // Add the scale value.
4966  if (AddrMode.Scale) {
4967  Value *V = AddrMode.ScaledReg;
4968  if (V->getType() == IntPtrTy) {
4969  // done.
4970  } else if (V->getType()->isPointerTy()) {
4971  V = Builder.CreatePtrToInt(V, IntPtrTy, "sunkaddr");
4972  } else if (cast<IntegerType>(IntPtrTy)->getBitWidth() <
4973  cast<IntegerType>(V->getType())->getBitWidth()) {
4974  V = Builder.CreateTrunc(V, IntPtrTy, "sunkaddr");
4975  } else {
4976  // It is only safe to sign extend the BaseReg if we know that the math
4977  // required to create it did not overflow before we extend it. Since
4978  // the original IR value was tossed in favor of a constant back when
4979  // the AddrMode was created we need to bail out gracefully if widths
4980  // do not match instead of extending it.
4981  Instruction *I = dyn_cast_or_null<Instruction>(Result);
4982  if (I && (Result != AddrMode.BaseReg))
4983  I->eraseFromParent();
4984  return false;
4985  }
4986  if (AddrMode.Scale != 1)
4987  V = Builder.CreateMul(V, ConstantInt::get(IntPtrTy, AddrMode.Scale),
4988  "sunkaddr");
4989  if (Result)
4990  Result = Builder.CreateAdd(Result, V, "sunkaddr");
4991  else
4992  Result = V;
4993  }
4994 
4995  // Add in the BaseGV if present.
4996  if (AddrMode.BaseGV) {
4997  Value *V = Builder.CreatePtrToInt(AddrMode.BaseGV, IntPtrTy, "sunkaddr");
4998  if (Result)
4999  Result = Builder.CreateAdd(Result, V, "sunkaddr");
5000  else
5001  Result = V;
5002  }
5003 
5004  // Add in the Base Offset if present.
5005  if (AddrMode.BaseOffs) {
5006  Value *V = ConstantInt::get(IntPtrTy, AddrMode.BaseOffs);
5007  if (Result)
5008  Result = Builder.CreateAdd(Result, V, "sunkaddr");
5009  else
5010  Result = V;
5011  }
5012 
5013  if (!Result)
5014  SunkAddr = Constant::getNullValue(Addr->getType());
5015  else
5016  SunkAddr = Builder.CreateIntToPtr(Result, Addr->getType(), "sunkaddr");
5017  }
5018 
5019  MemoryInst->replaceUsesOfWith(Repl, SunkAddr);
5020  // Store the newly computed address into the cache. In the case we reused a
5021  // value, this should be idempotent.
5022  SunkAddrs[Addr] = WeakTrackingVH(SunkAddr);
5023 
5024  // If we have no uses, recursively delete the value and all dead instructions
5025  // using it.
5026  if (Repl->use_empty()) {
5027  // This can cause recursive deletion, which can invalidate our iterator.
5028  // Use a WeakTrackingVH to hold onto it in case this happens.
5029  Value *CurValue = &*CurInstIterator;
5030  WeakTrackingVH IterHandle(CurValue);
5031  BasicBlock *BB = CurInstIterator->getParent();
5032 
5034 
5035  if (IterHandle != CurValue) {
5036  // If the iterator instruction was recursively deleted, start over at the
5037  // start of the block.
5038  CurInstIterator = BB->begin();
5039  SunkAddrs.clear();
5040  }
5041  }
5042  ++NumMemoryInsts;
5043  return true;
5044 }
5045 
5046 /// If there are any memory operands, use OptimizeMemoryInst to sink their
5047 /// address computing into the block when possible / profitable.
5048 bool CodeGenPrepare::optimizeInlineAsmInst(CallInst *CS) {
5049  bool MadeChange = false;
5050 
5051  const TargetRegisterInfo *TRI =
5052  TM->getSubtargetImpl(*CS->getFunction())->getRegisterInfo();
5053  TargetLowering::AsmOperandInfoVector TargetConstraints =
5054  TLI->ParseConstraints(*DL, TRI, CS);
5055  unsigned ArgNo = 0;
5056  for (unsigned i = 0, e = TargetConstraints.size(); i != e; ++i) {
5057  TargetLowering::AsmOperandInfo &OpInfo = TargetConstraints[i];
5058 
5059  // Compute the constraint code and ConstraintType to use.
5060  TLI->ComputeConstraintToUse(OpInfo, SDValue());
5061 
5062  if (OpInfo.ConstraintType == TargetLowering::C_Memory &&
5063  OpInfo.isIndirect) {
5064  Value *OpVal = CS->getArgOperand(ArgNo++);
5065  MadeChange |= optimizeMemoryInst(CS, OpVal, OpVal->getType(), ~0u);
5066  } else if (OpInfo.Type == InlineAsm::isInput)
5067  ArgNo++;
5068  }
5069 
5070  return MadeChange;
5071 }
5072 
5073 /// Check if all the uses of \p Val are equivalent (or free) zero or
5074 /// sign extensions.
5075 static bool hasSameExtUse(Value *Val, const TargetLowering &TLI) {
5076  assert(!Val->use_empty() && "Input must have at least one use");
5077  const Instruction *FirstUser = cast<Instruction>(*Val->user_begin());
5078  bool IsSExt = isa<SExtInst>(FirstUser);
5079  Type *ExtTy = FirstUser->getType();
5080  for (const User *U : Val->users()) {
5081  const Instruction *UI = cast<Instruction>(U);
5082  if ((IsSExt && !isa<SExtInst>(UI)) || (!IsSExt && !isa<ZExtInst>(UI)))
5083  return false;
5084  Type *CurTy = UI->getType();
5085  // Same input and output types: Same instruction after CSE.
5086  if (CurTy == ExtTy)
5087  continue;
5088 
5089  // If IsSExt is true, we are in this situation:
5090  // a = Val
5091  // b = sext ty1 a to ty2
5092  // c = sext ty1 a to ty3
5093  // Assuming ty2 is shorter than ty3, this could be turned into:
5094  // a = Val
5095  // b = sext ty1 a to ty2
5096  // c = sext ty2 b to ty3
5097  // However, the last sext is not free.
5098  if (IsSExt)
5099  return false;
5100 
5101  // This is a ZExt, maybe this is free to extend from one type to another.
5102  // In that case, we would not account for a different use.
5103  Type *NarrowTy;
5104  Type *LargeTy;
5105  if (ExtTy->getScalarType()->getIntegerBitWidth() >
5106  CurTy->getScalarType()->getIntegerBitWidth()) {
5107  NarrowTy = CurTy;
5108  LargeTy = ExtTy;
5109  } else {
5110  NarrowTy = ExtTy;
5111  LargeTy = CurTy;
5112  }
5113 
5114  if (!TLI.isZExtFree(NarrowTy, LargeTy))
5115  return false;
5116  }
5117  // All uses are the same or can be derived from one another for free.
5118  return true;
5119 }
5120 
5121 /// Try to speculatively promote extensions in \p Exts and continue
5122 /// promoting through newly promoted operands recursively as far as doing so is
5123 /// profitable. Save extensions profitably moved up, in \p ProfitablyMovedExts.
5124 /// When some promotion happened, \p TPT contains the proper state to revert
5125 /// them.
5126 ///
5127 /// \return true if some promotion happened, false otherwise.
5128 bool CodeGenPrepare::tryToPromoteExts(
5129  TypePromotionTransaction &TPT, const SmallVectorImpl<Instruction *> &Exts,
5130  SmallVectorImpl<Instruction *> &ProfitablyMovedExts,
5131  unsigned CreatedInstsCost) {
5132  bool Promoted = false;
5133 
5134  // Iterate over all the extensions to try to promote them.
5135  for (auto I : Exts) {
5136  // Early check if we directly have ext(load).
5137  if (isa<LoadInst>(I->getOperand(0))) {
5138  ProfitablyMovedExts.push_back(I);
5139  continue;
5140  }
5141 
5142  // Check whether or not we want to do any promotion. The reason we have
5143  // this check inside the for loop is to catch the case where an extension
5144  // is directly fed by a load because in such case the extension can be moved
5145  // up without any promotion on its operands.
5146  if (!TLI || !TLI->enableExtLdPromotion() || DisableExtLdPromotion)
5147  return false;
5148 
5149  // Get the action to perform the promotion.
5150  TypePromotionHelper::Action TPH =
5151  TypePromotionHelper::getAction(I, InsertedInsts, *TLI, PromotedInsts);
5152  // Check if we can promote.
5153  if (!TPH) {
5154  // Save the current extension as we cannot move up through its operand.
5155  ProfitablyMovedExts.push_back(I);
5156  continue;
5157  }
5158 
5159  // Save the current state.
5160  TypePromotionTransaction::ConstRestorationPt LastKnownGood =
5161  TPT.getRestorationPoint();
5163  unsigned NewCreatedInstsCost = 0;
5164  unsigned ExtCost = !TLI->isExtFree(I);
5165  // Promote.
5166  Value *PromotedVal = TPH(I, TPT, PromotedInsts, NewCreatedInstsCost,
5167  &NewExts, nullptr, *TLI);
5168  assert(PromotedVal &&
5169  "TypePromotionHelper should have filtered out those cases");
5170 
5171  // We would be able to merge only one extension in a load.
5172  // Therefore, if we have more than 1 new extension we heuristically
5173  // cut this search path, because it means we degrade the code quality.
5174  // With exactly 2, the transformation is neutral, because we will merge
5175  // one extension but leave one. However, we optimistically keep going,
5176  // because the new extension may be removed too.
5177  long long TotalCreatedInstsCost = CreatedInstsCost + NewCreatedInstsCost;
5178  // FIXME: It would be possible to propagate a negative value instead of
5179  // conservatively ceiling it to 0.
5180  TotalCreatedInstsCost =
5181  std::max((long long)0, (TotalCreatedInstsCost - ExtCost));
5182  if (!StressExtLdPromotion &&
5183  (TotalCreatedInstsCost > 1 ||
5184  !isPromotedInstructionLegal(*TLI, *DL, PromotedVal))) {
5185  // This promotion is not profitable, rollback to the previous state, and
5186  // save the current extension in ProfitablyMovedExts as the latest
5187  // speculative promotion turned out to be unprofitable.
5188  TPT.rollback(LastKnownGood);
5189  ProfitablyMovedExts.push_back(I);
5190  continue;
5191  }
5192  // Continue promoting NewExts as far as doing so is profitable.
5193  SmallVector<Instruction *, 2> NewlyMovedExts;
5194  (void)tryToPromoteExts(TPT, NewExts, NewlyMovedExts, TotalCreatedInstsCost);
5195  bool NewPromoted = false;
5196  for (auto ExtInst : NewlyMovedExts) {
5197  Instruction *MovedExt = cast<Instruction>(ExtInst);
5198  Value *ExtOperand = MovedExt->getOperand(0);
5199  // If we have reached to a load, we need this extra profitability check
5200  // as it could potentially be merged into an ext(load).
5201  if (isa<LoadInst>(ExtOperand) &&
5202  !(StressExtLdPromotion || NewCreatedInstsCost <= ExtCost ||
5203  (ExtOperand->hasOneUse() || hasSameExtUse(ExtOperand, *TLI))))
5204  continue;
5205 
5206  ProfitablyMovedExts.push_back(MovedExt);
5207  NewPromoted = true;
5208  }
5209 
5210  // If none of speculative promotions for NewExts is profitable, rollback
5211  // and save the current extension (I) as the last profitable extension.
5212  if (!NewPromoted) {
5213  TPT.rollback(LastKnownGood);
5214  ProfitablyMovedExts.push_back(I);
5215  continue;
5216  }
5217  // The promotion is profitable.
5218  Promoted = true;
5219  }
5220  return Promoted;
5221 }
5222 
5223 /// Merging redundant sexts when one is dominating the other.
5224 bool CodeGenPrepare::mergeSExts(Function &F) {
5225  bool Changed = false;
5226  for (auto &Entry : ValToSExtendedUses) {
5227  SExts &Insts = Entry.second;
5228  SExts CurPts;
5229  for (Instruction *Inst : Insts) {
5230  if (RemovedInsts.count(Inst) || !isa<SExtInst>(Inst) ||
5231  Inst->getOperand(0) != Entry.first)
5232  continue;
5233  bool inserted = false;
5234  for (auto &Pt : CurPts) {
5235  if (getDT(F).dominates(Inst, Pt)) {
5236  Pt->replaceAllUsesWith(Inst);
5237  RemovedInsts.insert(Pt);
5238  Pt->removeFromParent();
5239  Pt = Inst;
5240  inserted = true;
5241  Changed = true;
5242  break;
5243  }
5244  if (!getDT(F).dominates(Pt, Inst))
5245  // Give up if we need to merge in a common dominator as the
5246  // experiments show it is not profitable.
5247  continue;
5248  Inst->replaceAllUsesWith(Pt);
5249  RemovedInsts.insert(Inst);
5250  Inst->removeFromParent();
5251  inserted = true;
5252  Changed = true;
5253  break;
5254  }
5255  if (!inserted)
5256  CurPts.push_back(Inst);
5257  }
5258  }
5259  return Changed;
5260 }
5261 
5262 // Spliting large data structures so that the GEPs accessing them can have
5263 // smaller offsets so that they can be sunk to the same blocks as their users.
5264 // For example, a large struct starting from %base is splitted into two parts
5265 // where the second part starts from %new_base.
5266 //
5267 // Before:
5268 // BB0:
5269 // %base =
5270 //
5271 // BB1:
5272 // %gep0 = gep %base, off0
5273 // %gep1 = gep %base, off1
5274 // %gep2 = gep %base, off2
5275 //
5276 // BB2:
5277 // %load1 = load %gep0
5278 // %load2 = load %gep1
5279 // %load3 = load %gep2
5280 //
5281 // After:
5282 // BB0:
5283 // %base =
5284 // %new_base = gep %base, off0
5285 //
5286 // BB1:
5287 // %new_gep0 = %new_base
5288 // %new_gep1 = gep %new_base, off1 - off0
5289 // %new_gep2 = gep %new_base, off2 - off0
5290 //
5291 // BB2:
5292 // %load1 = load i32, i32* %new_gep0
5293 // %load2 = load i32, i32* %new_gep1
5294 // %load3 = load i32, i32* %new_gep2
5295 //
5296 // %new_gep1 and %new_gep2 can be sunk to BB2 now after the splitting because
5297 // their offsets are smaller enough to fit into the addressing mode.
5298 bool CodeGenPrepare::splitLargeGEPOffsets() {
5299  bool Changed = false;
5300  for (auto &Entry : LargeOffsetGEPMap) {
5301  Value *OldBase = Entry.first;
5303  &LargeOffsetGEPs = Entry.second;
5304  auto compareGEPOffset =
5305  [&](const std::pair<GetElementPtrInst *, int64_t> &LHS,
5306  const std::pair<GetElementPtrInst *, int64_t> &RHS) {
5307  if (LHS.first == RHS.first)
5308  return false;
5309  if (LHS.second != RHS.second)
5310  return LHS.second < RHS.second;
5311  return LargeOffsetGEPID[LHS.first] < LargeOffsetGEPID[RHS.first];
5312  };
5313  // Sorting all the GEPs of the same data structures based on the offsets.
5314  llvm::sort(LargeOffsetGEPs, compareGEPOffset);
5315  LargeOffsetGEPs.erase(
5316  std::unique(LargeOffsetGEPs.begin(), LargeOffsetGEPs.end()),
5317  LargeOffsetGEPs.end());
5318  // Skip if all the GEPs have the same offsets.
5319  if (LargeOffsetGEPs.front().second == LargeOffsetGEPs.back().second)
5320  continue;
5321  GetElementPtrInst *BaseGEP = LargeOffsetGEPs.begin()->first;
5322  int64_t BaseOffset = LargeOffsetGEPs.begin()->second;
5323  Value *NewBaseGEP = nullptr;
5324 
5325  auto LargeOffsetGEP = LargeOffsetGEPs.begin();
5326  while (LargeOffsetGEP != LargeOffsetGEPs.end()) {
5327  GetElementPtrInst *GEP = LargeOffsetGEP->first;
5328  int64_t Offset = LargeOffsetGEP->second;
5329  if (Offset != BaseOffset) {
5331  AddrMode.BaseOffs = Offset - BaseOffset;
5332  // The result type of the GEP might not be the type of the memory
5333  // access.
5334  if (!TLI->isLegalAddressingMode(*DL, AddrMode,
5335  GEP->getResultElementType(),
5336  GEP->getAddressSpace())) {
5337  // We need to create a new base if the offset to the current base is
5338  // too large to fit into the addressing mode. So, a very large struct
5339  // may be splitted into several parts.
5340  BaseGEP = GEP;
5341  BaseOffset = Offset;
5342  NewBaseGEP = nullptr;
5343  }
5344  }
5345 
5346  // Generate a new GEP to replace the current one.
5347  LLVMContext &Ctx = GEP->getContext();
5348  Type *IntPtrTy = DL->getIntPtrType(GEP->getType());
5349  Type *I8PtrTy =
5351  Type *I8Ty = Type::getInt8Ty(Ctx);
5352 
5353  if (!NewBaseGEP) {
5354  // Create a new base if we don't have one yet. Find the insertion
5355  // pointer for the new base first.
5356  BasicBlock::iterator NewBaseInsertPt;
5357  BasicBlock *NewBaseInsertBB;
5358  if (auto *BaseI = dyn_cast<Instruction>(OldBase)) {
5359  // If the base of the struct is an instruction, the new base will be
5360  // inserted close to it.
5361  NewBaseInsertBB = BaseI->getParent();
5362  if (isa<PHINode>(BaseI))
5363  NewBaseInsertPt = NewBaseInsertBB->getFirstInsertionPt();
5364  else if (InvokeInst *Invoke = dyn_cast<InvokeInst>(BaseI)) {
5365  NewBaseInsertBB =
5366  SplitEdge(NewBaseInsertBB, Invoke->getNormalDest());
5367  NewBaseInsertPt = NewBaseInsertBB->getFirstInsertionPt();
5368  } else
5369  NewBaseInsertPt = std::next(BaseI->getIterator());
5370  } else {
5371  // If the current base is an argument or global value, the new base
5372  // will be inserted to the entry block.
5373  NewBaseInsertBB = &BaseGEP->getFunction()->getEntryBlock();
5374  NewBaseInsertPt = NewBaseInsertBB->getFirstInsertionPt();
5375  }
5376  IRBuilder<> NewBaseBuilder(NewBaseInsertBB, NewBaseInsertPt);
5377  // Create a new base.
5378  Value *BaseIndex = ConstantInt::get(IntPtrTy, BaseOffset);
5379  NewBaseGEP = OldBase;
5380  if (NewBaseGEP->getType() != I8PtrTy)
5381  NewBaseGEP = NewBaseBuilder.CreatePointerCast(NewBaseGEP, I8PtrTy);
5382  NewBaseGEP =
5383  NewBaseBuilder.CreateGEP(I8Ty, NewBaseGEP, BaseIndex, "splitgep");
5384  NewGEPBases.insert(NewBaseGEP);
5385  }
5386 
5387  IRBuilder<> Builder(GEP);
5388  Value *NewGEP = NewBaseGEP;
5389  if (Offset == BaseOffset) {
5390  if (GEP->getType() != I8PtrTy)
5391  NewGEP = Builder.CreatePointerCast(NewGEP, GEP->getType());
5392  } else {
5393  // Calculate the new offset for the new GEP.
5394  Value *Index = ConstantInt::get(IntPtrTy, Offset - BaseOffset);
5395  NewGEP = Builder.CreateGEP(I8Ty, NewBaseGEP, Index);
5396 
5397  if (GEP->getType() != I8PtrTy)
5398  NewGEP = Builder.CreatePointerCast(NewGEP, GEP->getType());
5399  }
5400  GEP->replaceAllUsesWith(NewGEP);
5401  LargeOffsetGEPID.erase(GEP);
5402  LargeOffsetGEP = LargeOffsetGEPs.erase(LargeOffsetGEP);
5403  GEP->eraseFromParent();
5404  Changed = true;
5405  }
5406  }
5407  return Changed;
5408 }
5409 
5410 /// Return true, if an ext(load) can be formed from an extension in
5411 /// \p MovedExts.
5412 bool CodeGenPrepare::canFormExtLd(
5413  const SmallVectorImpl<Instruction *> &MovedExts, LoadInst *&LI,
5414  Instruction *&Inst, bool HasPromoted) {
5415  for (auto *MovedExtInst : MovedExts) {
5416  if (isa<LoadInst>(MovedExtInst->getOperand(0))) {
5417  LI = cast<LoadInst>(MovedExtInst->getOperand(0));
5418  Inst = MovedExtInst;
5419  break;
5420  }
5421  }
5422  if (!LI)
5423  return false;
5424 
5425  // If they're already in the same block, there's nothing to do.
5426  // Make the cheap checks first if we did not promote.
5427  // If we promoted, we need to check if it is indeed profitable.
5428  if (!HasPromoted && LI->getParent() == Inst->getParent())
5429  return false;
5430 
5431  return TLI->isExtLoad(LI, Inst, *DL);
5432 }
5433 
5434 /// Move a zext or sext fed by a load into the same basic block as the load,
5435 /// unless conditions are unfavorable. This allows SelectionDAG to fold the
5436 /// extend into the load.
5437 ///
5438 /// E.g.,
5439 /// \code
5440 /// %ld = load i32* %addr
5441 /// %add = add nuw i32 %ld, 4
5442 /// %zext = zext i32 %add to i64
5443 // \endcode
5444 /// =>
5445 /// \code
5446 /// %ld = load i32* %addr
5447 /// %zext = zext i32 %ld to i64
5448 /// %add = add nuw i64 %zext, 4
5449 /// \encode
5450 /// Note that the promotion in %add to i64 is done in tryToPromoteExts(), which
5451 /// allow us to match zext(load i32*) to i64.
5452 ///
5453 /// Also, try to promote the computations used to obtain a sign extended
5454 /// value used into memory accesses.
5455 /// E.g.,
5456 /// \code
5457 /// a = add nsw i32 b, 3
5458 /// d = sext i32 a to i64
5459 /// e = getelementptr ..., i64 d
5460 /// \endcode
5461 /// =>
5462 /// \code
5463 /// f = sext i32 b to i64
5464 /// a = add nsw i64 f, 3
5465 /// e = getelementptr ..., i64 a
5466 /// \endcode
5467 ///
5468 /// \p Inst[in/out] the extension may be modified during the process if some
5469 /// promotions apply.
5470 bool CodeGenPrepare::optimizeExt(Instruction *&Inst) {
5471  // ExtLoad formation and address type promotion infrastructure requires TLI to
5472  // be effective.
5473  if (!TLI)
5474  return false;
5475 
5476  bool AllowPromotionWithoutCommonHeader = false;
5477  /// See if it is an interesting sext operations for the address type
5478  /// promotion before trying to promote it, e.g., the ones with the right
5479  /// type and used in memory accesses.
5480  bool ATPConsiderable = TTI->shouldConsiderAddressTypePromotion(
5481  *Inst, AllowPromotionWithoutCommonHeader);
5482  TypePromotionTransaction TPT(RemovedInsts);
5483  TypePromotionTransaction::ConstRestorationPt LastKnownGood =
5484  TPT.getRestorationPoint();
5486  SmallVector<Instruction *, 2> SpeculativelyMovedExts;
5487  Exts.push_back(Inst);
5488 
5489  bool HasPromoted = tryToPromoteExts(TPT, Exts, SpeculativelyMovedExts);
5490 
5491  // Look for a load being extended.
5492  LoadInst *LI = nullptr;
5493  Instruction *ExtFedByLoad;
5494 
5495  // Try to promote a chain of computation if it allows to form an extended
5496  // load.
5497  if (canFormExtLd(SpeculativelyMovedExts, LI, ExtFedByLoad, HasPromoted)) {
5498  assert(LI && ExtFedByLoad && "Expect a valid load and extension");
5499  TPT.commit();
5500  // Move the extend into the same block as the load
5501  ExtFedByLoad->moveAfter(LI);
5502  // CGP does not check if the zext would be speculatively executed when moved
5503  // to the same basic block as the load. Preserving its original location
5504  // would pessimize the debugging experience, as well as negatively impact
5505  // the quality of sample pgo. We don't want to use "line 0" as that has a
5506  // size cost in the line-table section and logically the zext can be seen as
5507  // part of the load. Therefore we conservatively reuse the same debug
5508  // location for the load and the zext.
5509  ExtFedByLoad->setDebugLoc(LI->getDebugLoc());
5510  ++NumExtsMoved;
5511  Inst = ExtFedByLoad;
5512  return true;
5513  }
5514 
5515  // Continue promoting SExts if known as considerable depending on targets.
5516  if (ATPConsiderable &&
5517  performAddressTypePromotion(Inst, AllowPromotionWithoutCommonHeader,
5518  HasPromoted, TPT, SpeculativelyMovedExts))
5519  return true;
5520 
5521  TPT.rollback(LastKnownGood);
5522  return false;
5523 }
5524 
5525 // Perform address type promotion if doing so is profitable.
5526 // If AllowPromotionWithoutCommonHeader == false, we should find other sext
5527 // instructions that sign extended the same initial value. However, if
5528 // AllowPromotionWithoutCommonHeader == true, we expect promoting the
5529 // extension is just profitable.
5530 bool CodeGenPrepare::performAddressTypePromotion(
5531  Instruction *&Inst, bool AllowPromotionWithoutCommonHeader,
5532  bool HasPromoted, TypePromotionTransaction &TPT,
5533  SmallVectorImpl<Instruction *> &SpeculativelyMovedExts) {
5534  bool Promoted = false;
5535  SmallPtrSet<Instruction *, 1> UnhandledExts;
5536  bool AllSeenFirst = true;
5537  for (auto I : SpeculativelyMovedExts) {
5538  Value *HeadOfChain = I->getOperand(0);
5540  SeenChainsForSExt.find(HeadOfChain);
5541  // If there is an unhandled SExt which has the same header, try to promote
5542  // it as well.
5543  if (AlreadySeen != SeenChainsForSExt.end()) {
5544  if (AlreadySeen->second != nullptr)
5545  UnhandledExts.insert(AlreadySeen->second);
5546  AllSeenFirst = false;
5547  }
5548  }
5549 
5550  if (!AllSeenFirst || (AllowPromotionWithoutCommonHeader &&
5551  SpeculativelyMovedExts.size() == 1)) {
5552  TPT.commit();
5553  if (HasPromoted)
5554  Promoted = true;
5555  for (auto I : SpeculativelyMovedExts) {
5556  Value *HeadOfChain = I->getOperand(0);
5557  SeenChainsForSExt[HeadOfChain] = nullptr;
5558  ValToSExtendedUses[HeadOfChain].push_back(I);
5559  }
5560  // Update Inst as promotion happen.
5561  Inst = SpeculativelyMovedExts.pop_back_val();
5562  } else {
5563  // This is the first chain visited from the header, keep the current chain
5564  // as unhandled. Defer to promote this until we encounter another SExt
5565  // chain derived from the same header.
5566  for (auto I : SpeculativelyMovedExts) {
5567  Value *HeadOfChain = I->getOperand(0);
5568  SeenChainsForSExt[HeadOfChain] = Inst;
5569  }
5570  return false;
5571  }
5572 
5573  if (!AllSeenFirst && !UnhandledExts.empty())
5574  for (auto VisitedSExt : UnhandledExts) {
5575  if (RemovedInsts.count(VisitedSExt))
5576  continue;
5577  TypePromotionTransaction TPT(RemovedInsts);
5580  Exts.push_back(VisitedSExt);
5581  bool HasPromoted = tryToPromoteExts(TPT, Exts, Chains);
5582  TPT.commit();
5583  if (HasPromoted)
5584  Promoted = true;
5585  for (auto I : Chains) {
5586  Value *HeadOfChain = I->getOperand(0);
5587  // Mark this as handled.
5588  SeenChainsForSExt[HeadOfChain] = nullptr;
5589  ValToSExtendedUses[HeadOfChain].push_back(I);
5590  }
5591  }
5592  return Promoted;
5593 }
5594 
5595 bool CodeGenPrepare::optimizeExtUses(Instruction *I) {
5596  BasicBlock *DefBB = I->getParent();
5597 
5598  // If the result of a {s|z}ext and its source are both live out, rewrite all
5599  // other uses of the source with result of extension.
5600  Value *Src = I->getOperand(0);
5601  if (Src->hasOneUse())
5602  return false;
5603 
5604  // Only do this xform if truncating is free.
5605  if (TLI && !TLI->isTruncateFree(I->getType(), Src->getType()))
5606  return false;
5607 
5608  // Only safe to perform the optimization if the source is also defined in
5609  // this block.
5610  if (!isa<Instruction>(Src) || DefBB != cast<Instruction>(Src)->getParent())
5611  return false;
5612 
5613  bool DefIsLiveOut = false;
5614  for (User *U : I->users()) {
5615  Instruction *UI = cast<Instruction>(U);
5616 
5617  // Figure out which BB this ext is used in.
5618  BasicBlock *UserBB = UI->getParent();
5619  if (UserBB == DefBB) continue;
5620  DefIsLiveOut = true;
5621  break;
5622  }
5623  if (!DefIsLiveOut)
5624  return false;
5625 
5626  // Make sure none of the uses are PHI nodes.
5627  for (User *U : Src->users()) {
5628  Instruction *UI = cast<Instruction>(U);
5629  BasicBlock *UserBB = UI->getParent();
5630  if (UserBB == DefBB) continue;
5631  // Be conservative. We don't want this xform to end up introducing
5632  // reloads just before load / store instructions.
5633  if (isa<PHINode>(UI) || isa<LoadInst>(UI) || isa<StoreInst>(UI))
5634  return false;
5635  }
5636 
5637  // InsertedTruncs - Only insert one trunc in each block once.
5638  DenseMap<BasicBlock*, Instruction*> InsertedTruncs;
5639 
5640  bool MadeChange = false;
5641  for (Use &U : Src->uses()) {
5642  Instruction *User = cast<Instruction>(U.getUser());
5643 
5644  // Figure out which BB this ext is used in.
5645  BasicBlock *UserBB = User->getParent();
5646  if (UserBB == DefBB) continue;
5647 
5648  // Both src and def are live in this block. Rewrite the use.
5649  Instruction *&InsertedTrunc = InsertedTruncs[UserBB];
5650 
5651  if (!InsertedTrunc) {
5652  BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
5653  assert(InsertPt != UserBB->end());
5654  InsertedTrunc = new TruncInst(I, Src->getType(), "", &*InsertPt);
5655  InsertedInsts.insert(InsertedTrunc);
5656  }
5657 
5658  // Replace a use of the {s|z}ext source with a use of the result.
5659  U = InsertedTrunc;
5660  ++NumExtUses;
5661  MadeChange = true;
5662  }
5663 
5664  return MadeChange;
5665 }
5666 
5667 // Find loads whose uses only use some of the loaded value's bits. Add an "and"
5668 // just after the load if the target can fold this into one extload instruction,
5669 // with the hope of eliminating some of the other later "and" instructions using
5670 // the loaded value. "and"s that are made trivially redundant by the insertion
5671 // of the new "and" are removed by this function, while others (e.g. those whose
5672 // path from the load goes through a phi) are left for isel to potentially
5673 // remove.
5674 //
5675 // For example:
5676 //
5677 // b0:
5678 // x = load i32
5679 // ...
5680 // b1:
5681 // y = and x, 0xff
5682 // z = use y
5683 //
5684 // becomes:
5685 //
5686 // b0:
5687 // x = load i32
5688 // x' = and x, 0xff
5689 // ...
5690 // b1:
5691 // z = use x'
5692 //
5693 // whereas:
5694 //
5695 // b0:
5696 // x1 = load i32
5697 // ...
5698 // b1:
5699 // x2 = load i32
5700 // ...
5701 // b2:
5702 // x = phi x1, x2
5703 // y = and x, 0xff
5704 //
5705 // becomes (after a call to optimizeLoadExt for each load):
5706 //
5707 // b0:
5708 // x1 = load i32
5709 // x1' = and x1, 0xff
5710 // ...
5711 // b1:
5712 // x2 = load i32
5713 // x2' = and x2, 0xff
5714 // ...
5715 // b2:
5716 // x = phi x1', x2'
5717 // y = and x, 0xff
5718 bool CodeGenPrepare::optimizeLoadExt(LoadInst *Load) {
5719  if (!Load->isSimple() || !Load->getType()->isIntOrPtrTy())
5720  return false;
5721 
5722  // Skip loads we've already transformed.
5723  if (Load->hasOneUse() &&
5724  InsertedInsts.count(cast<Instruction>(*Load->user_begin())))
5725  return false;
5726 
5727  // Look at all uses of Load, looking through phis, to determine how many bits
5728  // of the loaded value are needed.
5731  SmallVector<Instruction *, 8> AndsToMaybeRemove;
5732  for (auto *U : Load->users())
5733  WorkList.push_back(cast<Instruction>(U));
5734 
5735  EVT LoadResultVT = TLI->getValueType(*DL, Load->getType());
5736  unsigned BitWidth = LoadResultVT.getSizeInBits();
5737  APInt DemandBits(BitWidth, 0);
5738  APInt WidestAndBits(BitWidth, 0);
5739 
5740  while (!WorkList.empty()) {
5741  Instruction *I = WorkList.back();
5742  WorkList.pop_back();
5743 
5744  // Break use-def graph loops.
5745  if (!Visited.insert(I).second)
5746  continue;
5747 
5748  // For a PHI node, push all of its users.
5749  if (auto *Phi = dyn_cast<PHINode>(I)) {
5750  for (auto *U : Phi->users())
5751  WorkList.push_back(cast<Instruction>(U));
5752  continue;
5753  }
5754 
5755  switch (I->getOpcode()) {
5756  case Instruction::And: {
5757  auto *AndC = dyn_cast<ConstantInt>(I->getOperand(1));
5758  if (!AndC)
5759  return false;
5760  APInt AndBits = AndC->getValue();
5761  DemandBits |= AndBits;
5762  // Keep track of the widest and mask we see.
5763  if (AndBits.ugt(WidestAndBits))
5764  WidestAndBits = AndBits;
5765  if (AndBits == WidestAndBits && I->getOperand(0) == Load)
5766  AndsToMaybeRemove.push_back(I);
5767  break;
5768  }
5769 
5770  case Instruction::Shl: {
5771  auto *ShlC = dyn_cast<ConstantInt>(I->getOperand(1));
5772  if (!ShlC)
5773  return false;
5774  uint64_t ShiftAmt = ShlC->getLimitedValue(BitWidth - 1);
5775  DemandBits.setLowBits(BitWidth - ShiftAmt);
5776  break;
5777  }
5778 
5779  case Instruction::Trunc: {
5780  EVT TruncVT = TLI->getValueType(*DL, I->getType());
5781  unsigned TruncBitWidth = TruncVT.getSizeInBits();
5782  DemandBits.setLowBits(TruncBitWidth);
5783  break;
5784  }
5785 
5786  default:
5787  return false;
5788  }
5789  }
5790 
5791  uint32_t ActiveBits = DemandBits.getActiveBits();
5792  // Avoid hoisting (and (load x) 1) since it is unlikely to be folded by the
5793  // target even if isLoadExtLegal says an i1 EXTLOAD is valid. For example,
5794  // for the AArch64 target isLoadExtLegal(ZEXTLOAD, i32, i1) returns true, but
5795  // (and (load x) 1) is not matched as a single instruction, rather as a LDR
5796  // followed by an AND.
5797  // TODO: Look into removing this restriction by fixing backends to either
5798  // return false for isLoadExtLegal for i1 or have them select this pattern to
5799  // a single instruction.
5800  //
5801  // Also avoid hoisting if we didn't see any ands with the exact DemandBits
5802  // mask, since these are the only ands that will be removed by isel.
5803  if (ActiveBits <= 1 || !DemandBits.isMask(ActiveBits) ||
5804  WidestAndBits != DemandBits)
5805  return false;
5806 
5807  LLVMContext &Ctx = Load->getType()->getContext();
5808  Type *TruncTy = Type::getIntNTy(Ctx, ActiveBits);
5809  EVT TruncVT = TLI->getValueType(*DL, TruncTy);
5810 
5811  // Reject cases that won't be matched as extloads.
5812  if (!LoadResultVT.bitsGT(TruncVT) || !TruncVT.isRound() ||
5813  !TLI->isLoadExtLegal(ISD::ZEXTLOAD, LoadResultVT, TruncVT))
5814  return false;
5815 
5816  IRBuilder<> Builder(Load->getNextNode());
5817  auto *NewAnd = dyn_cast<Instruction>(
5818  Builder.CreateAnd(Load, ConstantInt::get(Ctx, DemandBits)));
5819  // Mark this instruction as "inserted by CGP", so that other
5820  // optimizations don't touch it.
5821  InsertedInsts.insert(NewAnd);