1 //===- CodeGenPrepare.cpp - Prepare a function for code generation --------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This pass munges the code in the input function to better prepare it for
11 // SelectionDAG-based code generation. This works around limitations in it's
12 // basic-block-at-a-time approach. It should eventually be removed.
14 //===----------------------------------------------------------------------===//
16 #include "llvm/CodeGen/Passes.h"
17 #include "llvm/ADT/DenseMap.h"
18 #include "llvm/ADT/SmallSet.h"
19 #include "llvm/ADT/Statistic.h"
20 #include "llvm/Analysis/InstructionSimplify.h"
21 #include "llvm/Analysis/TargetLibraryInfo.h"
22 #include "llvm/Analysis/TargetTransformInfo.h"
23 #include "llvm/IR/CallSite.h"
24 #include "llvm/IR/Constants.h"
25 #include "llvm/IR/DataLayout.h"
26 #include "llvm/IR/DerivedTypes.h"
27 #include "llvm/IR/Dominators.h"
28 #include "llvm/IR/Function.h"
29 #include "llvm/IR/GetElementPtrTypeIterator.h"
30 #include "llvm/IR/IRBuilder.h"
31 #include "llvm/IR/InlineAsm.h"
32 #include "llvm/IR/Instructions.h"
33 #include "llvm/IR/IntrinsicInst.h"
34 #include "llvm/IR/MDBuilder.h"
35 #include "llvm/IR/PatternMatch.h"
36 #include "llvm/IR/Statepoint.h"
37 #include "llvm/IR/ValueHandle.h"
38 #include "llvm/IR/ValueMap.h"
39 #include "llvm/Pass.h"
40 #include "llvm/Support/CommandLine.h"
41 #include "llvm/Support/Debug.h"
42 #include "llvm/Support/raw_ostream.h"
43 #include "llvm/Target/TargetLowering.h"
44 #include "llvm/Target/TargetSubtargetInfo.h"
45 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
46 #include "llvm/Transforms/Utils/BuildLibCalls.h"
47 #include "llvm/Transforms/Utils/BypassSlowDivision.h"
48 #include "llvm/Transforms/Utils/Local.h"
49 #include "llvm/Transforms/Utils/SimplifyLibCalls.h"
51 using namespace llvm::PatternMatch;
53 #define DEBUG_TYPE "codegenprepare"
55 STATISTIC(NumBlocksElim, "Number of blocks eliminated");
56 STATISTIC(NumPHIsElim, "Number of trivial PHIs eliminated");
57 STATISTIC(NumGEPsElim, "Number of GEPs converted to casts");
58 STATISTIC(NumCmpUses, "Number of uses of Cmp expressions replaced with uses of "
60 STATISTIC(NumCastUses, "Number of uses of Cast expressions replaced with uses "
62 STATISTIC(NumMemoryInsts, "Number of memory instructions whose address "
63 "computations were sunk");
64 STATISTIC(NumExtsMoved, "Number of [s|z]ext instructions combined with loads");
65 STATISTIC(NumExtUses, "Number of uses of [s|z]ext instructions optimized");
66 STATISTIC(NumRetsDup, "Number of return instructions duplicated");
67 STATISTIC(NumDbgValueMoved, "Number of debug value instructions moved");
68 STATISTIC(NumSelectsExpanded, "Number of selects turned into branches");
69 STATISTIC(NumAndCmpsMoved, "Number of and/cmp's pushed into branches");
70 STATISTIC(NumStoreExtractExposed, "Number of store(extractelement) exposed");
72 static cl::opt<bool> DisableBranchOpts(
73 "disable-cgp-branch-opts", cl::Hidden, cl::init(false),
74 cl::desc("Disable branch optimizations in CodeGenPrepare"));
77 DisableGCOpts("disable-cgp-gc-opts", cl::Hidden, cl::init(false),
78 cl::desc("Disable GC optimizations in CodeGenPrepare"));
80 static cl::opt<bool> DisableSelectToBranch(
81 "disable-cgp-select2branch", cl::Hidden, cl::init(false),
82 cl::desc("Disable select to branch conversion."));
84 static cl::opt<bool> AddrSinkUsingGEPs(
85 "addr-sink-using-gep", cl::Hidden, cl::init(false),
86 cl::desc("Address sinking in CGP using GEPs."));
88 static cl::opt<bool> EnableAndCmpSinking(
89 "enable-andcmp-sinking", cl::Hidden, cl::init(true),
90 cl::desc("Enable sinkinig and/cmp into branches."));
92 static cl::opt<bool> DisableStoreExtract(
93 "disable-cgp-store-extract", cl::Hidden, cl::init(false),
94 cl::desc("Disable store(extract) optimizations in CodeGenPrepare"));
96 static cl::opt<bool> StressStoreExtract(
97 "stress-cgp-store-extract", cl::Hidden, cl::init(false),
98 cl::desc("Stress test store(extract) optimizations in CodeGenPrepare"));
100 static cl::opt<bool> DisableExtLdPromotion(
101 "disable-cgp-ext-ld-promotion", cl::Hidden, cl::init(false),
102 cl::desc("Disable ext(promotable(ld)) -> promoted(ext(ld)) optimization in "
105 static cl::opt<bool> StressExtLdPromotion(
106 "stress-cgp-ext-ld-promotion", cl::Hidden, cl::init(false),
107 cl::desc("Stress test ext(promotable(ld)) -> promoted(ext(ld)) "
108 "optimization in CodeGenPrepare"));
111 typedef SmallPtrSet<Instruction *, 16> SetOfInstrs;
115 TypeIsSExt(Type *Ty, bool IsSExt) : Ty(Ty), IsSExt(IsSExt) {}
117 typedef DenseMap<Instruction *, TypeIsSExt> InstrToOrigTy;
118 class TypePromotionTransaction;
120 class CodeGenPrepare : public FunctionPass {
121 /// TLI - Keep a pointer of a TargetLowering to consult for determining
122 /// transformation profitability.
123 const TargetMachine *TM;
124 const TargetLowering *TLI;
125 const TargetTransformInfo *TTI;
126 const TargetLibraryInfo *TLInfo;
128 /// CurInstIterator - As we scan instructions optimizing them, this is the
129 /// next instruction to optimize. Xforms that can invalidate this should
131 BasicBlock::iterator CurInstIterator;
133 /// Keeps track of non-local addresses that have been sunk into a block.
134 /// This allows us to avoid inserting duplicate code for blocks with
135 /// multiple load/stores of the same address.
136 ValueMap<Value*, Value*> SunkAddrs;
138 /// Keeps track of all truncates inserted for the current function.
139 SetOfInstrs InsertedTruncsSet;
140 /// Keeps track of the type of the related instruction before their
141 /// promotion for the current function.
142 InstrToOrigTy PromotedInsts;
144 /// ModifiedDT - If CFG is modified in anyway.
147 /// OptSize - True if optimizing for size.
151 static char ID; // Pass identification, replacement for typeid
152 explicit CodeGenPrepare(const TargetMachine *TM = nullptr)
153 : FunctionPass(ID), TM(TM), TLI(nullptr), TTI(nullptr) {
154 initializeCodeGenPreparePass(*PassRegistry::getPassRegistry());
156 bool runOnFunction(Function &F) override;
158 const char *getPassName() const override { return "CodeGen Prepare"; }
160 void getAnalysisUsage(AnalysisUsage &AU) const override {
161 AU.addPreserved<DominatorTreeWrapperPass>();
162 AU.addRequired<TargetLibraryInfoWrapperPass>();
163 AU.addRequired<TargetTransformInfoWrapperPass>();
167 bool EliminateFallThrough(Function &F);
168 bool EliminateMostlyEmptyBlocks(Function &F);
169 bool CanMergeBlocks(const BasicBlock *BB, const BasicBlock *DestBB) const;
170 void EliminateMostlyEmptyBlock(BasicBlock *BB);
171 bool OptimizeBlock(BasicBlock &BB, bool& ModifiedDT);
172 bool OptimizeInst(Instruction *I, bool& ModifiedDT);
173 bool OptimizeMemoryInst(Instruction *I, Value *Addr, Type *AccessTy);
174 bool OptimizeInlineAsmInst(CallInst *CS);
175 bool OptimizeCallInst(CallInst *CI, bool& ModifiedDT);
176 bool MoveExtToFormExtLoad(Instruction *&I);
177 bool OptimizeExtUses(Instruction *I);
178 bool OptimizeSelectInst(SelectInst *SI);
179 bool OptimizeShuffleVectorInst(ShuffleVectorInst *SI);
180 bool OptimizeExtractElementInst(Instruction *Inst);
181 bool DupRetToEnableTailCallOpts(BasicBlock *BB);
182 bool PlaceDbgValues(Function &F);
183 bool sinkAndCmp(Function &F);
184 bool ExtLdPromotion(TypePromotionTransaction &TPT, LoadInst *&LI,
186 const SmallVectorImpl<Instruction *> &Exts,
187 unsigned CreatedInstCost);
188 bool splitBranchCondition(Function &F);
189 bool simplifyOffsetableRelocate(Instruction &I);
193 char CodeGenPrepare::ID = 0;
194 INITIALIZE_TM_PASS(CodeGenPrepare, "codegenprepare",
195 "Optimize for code generation", false, false)
197 FunctionPass *llvm::createCodeGenPreparePass(const TargetMachine *TM) {
198 return new CodeGenPrepare(TM);
201 bool CodeGenPrepare::runOnFunction(Function &F) {
202 if (skipOptnoneFunction(F))
205 bool EverMadeChange = false;
206 // Clear per function information.
207 InsertedTruncsSet.clear();
208 PromotedInsts.clear();
212 TLI = TM->getSubtargetImpl(F)->getTargetLowering();
213 TLInfo = &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
214 TTI = &getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
215 OptSize = F.hasFnAttribute(Attribute::OptimizeForSize);
217 /// This optimization identifies DIV instructions that can be
218 /// profitably bypassed and carried out with a shorter, faster divide.
219 if (!OptSize && TLI && TLI->isSlowDivBypassed()) {
220 const DenseMap<unsigned int, unsigned int> &BypassWidths =
221 TLI->getBypassSlowDivWidths();
222 for (Function::iterator I = F.begin(); I != F.end(); I++)
223 EverMadeChange |= bypassSlowDivision(F, I, BypassWidths);
226 // Eliminate blocks that contain only PHI nodes and an
227 // unconditional branch.
228 EverMadeChange |= EliminateMostlyEmptyBlocks(F);
230 // llvm.dbg.value is far away from the value then iSel may not be able
231 // handle it properly. iSel will drop llvm.dbg.value if it can not
232 // find a node corresponding to the value.
233 EverMadeChange |= PlaceDbgValues(F);
235 // If there is a mask, compare against zero, and branch that can be combined
236 // into a single target instruction, push the mask and compare into branch
237 // users. Do this before OptimizeBlock -> OptimizeInst ->
238 // OptimizeCmpExpression, which perturbs the pattern being searched for.
239 if (!DisableBranchOpts) {
240 EverMadeChange |= sinkAndCmp(F);
241 EverMadeChange |= splitBranchCondition(F);
244 bool MadeChange = true;
247 for (Function::iterator I = F.begin(); I != F.end(); ) {
248 BasicBlock *BB = I++;
249 bool ModifiedDTOnIteration = false;
250 MadeChange |= OptimizeBlock(*BB, ModifiedDTOnIteration);
252 // Restart BB iteration if the dominator tree of the Function was changed
253 if (ModifiedDTOnIteration)
256 EverMadeChange |= MadeChange;
261 if (!DisableBranchOpts) {
263 SmallPtrSet<BasicBlock*, 8> WorkList;
264 for (BasicBlock &BB : F) {
265 SmallVector<BasicBlock *, 2> Successors(succ_begin(&BB), succ_end(&BB));
266 MadeChange |= ConstantFoldTerminator(&BB, true);
267 if (!MadeChange) continue;
269 for (SmallVectorImpl<BasicBlock*>::iterator
270 II = Successors.begin(), IE = Successors.end(); II != IE; ++II)
271 if (pred_begin(*II) == pred_end(*II))
272 WorkList.insert(*II);
275 // Delete the dead blocks and any of their dead successors.
276 MadeChange |= !WorkList.empty();
277 while (!WorkList.empty()) {
278 BasicBlock *BB = *WorkList.begin();
280 SmallVector<BasicBlock*, 2> Successors(succ_begin(BB), succ_end(BB));
284 for (SmallVectorImpl<BasicBlock*>::iterator
285 II = Successors.begin(), IE = Successors.end(); II != IE; ++II)
286 if (pred_begin(*II) == pred_end(*II))
287 WorkList.insert(*II);
290 // Merge pairs of basic blocks with unconditional branches, connected by
292 if (EverMadeChange || MadeChange)
293 MadeChange |= EliminateFallThrough(F);
295 EverMadeChange |= MadeChange;
298 if (!DisableGCOpts) {
299 SmallVector<Instruction *, 2> Statepoints;
300 for (BasicBlock &BB : F)
301 for (Instruction &I : BB)
303 Statepoints.push_back(&I);
304 for (auto &I : Statepoints)
305 EverMadeChange |= simplifyOffsetableRelocate(*I);
308 return EverMadeChange;
311 /// EliminateFallThrough - Merge basic blocks which are connected
312 /// by a single edge, where one of the basic blocks has a single successor
313 /// pointing to the other basic block, which has a single predecessor.
314 bool CodeGenPrepare::EliminateFallThrough(Function &F) {
315 bool Changed = false;
316 // Scan all of the blocks in the function, except for the entry block.
317 for (Function::iterator I = std::next(F.begin()), E = F.end(); I != E;) {
318 BasicBlock *BB = I++;
319 // If the destination block has a single pred, then this is a trivial
320 // edge, just collapse it.
321 BasicBlock *SinglePred = BB->getSinglePredecessor();
323 // Don't merge if BB's address is taken.
324 if (!SinglePred || SinglePred == BB || BB->hasAddressTaken()) continue;
326 BranchInst *Term = dyn_cast<BranchInst>(SinglePred->getTerminator());
327 if (Term && !Term->isConditional()) {
329 DEBUG(dbgs() << "To merge:\n"<< *SinglePred << "\n\n\n");
330 // Remember if SinglePred was the entry block of the function.
331 // If so, we will need to move BB back to the entry position.
332 bool isEntry = SinglePred == &SinglePred->getParent()->getEntryBlock();
333 MergeBasicBlockIntoOnlyPred(BB, nullptr);
335 if (isEntry && BB != &BB->getParent()->getEntryBlock())
336 BB->moveBefore(&BB->getParent()->getEntryBlock());
338 // We have erased a block. Update the iterator.
345 /// EliminateMostlyEmptyBlocks - eliminate blocks that contain only PHI nodes,
346 /// debug info directives, and an unconditional branch. Passes before isel
347 /// (e.g. LSR/loopsimplify) often split edges in ways that are non-optimal for
348 /// isel. Start by eliminating these blocks so we can split them the way we
350 bool CodeGenPrepare::EliminateMostlyEmptyBlocks(Function &F) {
351 bool MadeChange = false;
352 // Note that this intentionally skips the entry block.
353 for (Function::iterator I = std::next(F.begin()), E = F.end(); I != E;) {
354 BasicBlock *BB = I++;
356 // If this block doesn't end with an uncond branch, ignore it.
357 BranchInst *BI = dyn_cast<BranchInst>(BB->getTerminator());
358 if (!BI || !BI->isUnconditional())
361 // If the instruction before the branch (skipping debug info) isn't a phi
362 // node, then other stuff is happening here.
363 BasicBlock::iterator BBI = BI;
364 if (BBI != BB->begin()) {
366 while (isa<DbgInfoIntrinsic>(BBI)) {
367 if (BBI == BB->begin())
371 if (!isa<DbgInfoIntrinsic>(BBI) && !isa<PHINode>(BBI))
375 // Do not break infinite loops.
376 BasicBlock *DestBB = BI->getSuccessor(0);
380 if (!CanMergeBlocks(BB, DestBB))
383 EliminateMostlyEmptyBlock(BB);
389 /// CanMergeBlocks - Return true if we can merge BB into DestBB if there is a
390 /// single uncond branch between them, and BB contains no other non-phi
392 bool CodeGenPrepare::CanMergeBlocks(const BasicBlock *BB,
393 const BasicBlock *DestBB) const {
394 // We only want to eliminate blocks whose phi nodes are used by phi nodes in
395 // the successor. If there are more complex condition (e.g. preheaders),
396 // don't mess around with them.
397 BasicBlock::const_iterator BBI = BB->begin();
398 while (const PHINode *PN = dyn_cast<PHINode>(BBI++)) {
399 for (const User *U : PN->users()) {
400 const Instruction *UI = cast<Instruction>(U);
401 if (UI->getParent() != DestBB || !isa<PHINode>(UI))
403 // If User is inside DestBB block and it is a PHINode then check
404 // incoming value. If incoming value is not from BB then this is
405 // a complex condition (e.g. preheaders) we want to avoid here.
406 if (UI->getParent() == DestBB) {
407 if (const PHINode *UPN = dyn_cast<PHINode>(UI))
408 for (unsigned I = 0, E = UPN->getNumIncomingValues(); I != E; ++I) {
409 Instruction *Insn = dyn_cast<Instruction>(UPN->getIncomingValue(I));
410 if (Insn && Insn->getParent() == BB &&
411 Insn->getParent() != UPN->getIncomingBlock(I))
418 // If BB and DestBB contain any common predecessors, then the phi nodes in BB
419 // and DestBB may have conflicting incoming values for the block. If so, we
420 // can't merge the block.
421 const PHINode *DestBBPN = dyn_cast<PHINode>(DestBB->begin());
422 if (!DestBBPN) return true; // no conflict.
424 // Collect the preds of BB.
425 SmallPtrSet<const BasicBlock*, 16> BBPreds;
426 if (const PHINode *BBPN = dyn_cast<PHINode>(BB->begin())) {
427 // It is faster to get preds from a PHI than with pred_iterator.
428 for (unsigned i = 0, e = BBPN->getNumIncomingValues(); i != e; ++i)
429 BBPreds.insert(BBPN->getIncomingBlock(i));
431 BBPreds.insert(pred_begin(BB), pred_end(BB));
434 // Walk the preds of DestBB.
435 for (unsigned i = 0, e = DestBBPN->getNumIncomingValues(); i != e; ++i) {
436 BasicBlock *Pred = DestBBPN->getIncomingBlock(i);
437 if (BBPreds.count(Pred)) { // Common predecessor?
438 BBI = DestBB->begin();
439 while (const PHINode *PN = dyn_cast<PHINode>(BBI++)) {
440 const Value *V1 = PN->getIncomingValueForBlock(Pred);
441 const Value *V2 = PN->getIncomingValueForBlock(BB);
443 // If V2 is a phi node in BB, look up what the mapped value will be.
444 if (const PHINode *V2PN = dyn_cast<PHINode>(V2))
445 if (V2PN->getParent() == BB)
446 V2 = V2PN->getIncomingValueForBlock(Pred);
448 // If there is a conflict, bail out.
449 if (V1 != V2) return false;
458 /// EliminateMostlyEmptyBlock - Eliminate a basic block that have only phi's and
459 /// an unconditional branch in it.
460 void CodeGenPrepare::EliminateMostlyEmptyBlock(BasicBlock *BB) {
461 BranchInst *BI = cast<BranchInst>(BB->getTerminator());
462 BasicBlock *DestBB = BI->getSuccessor(0);
464 DEBUG(dbgs() << "MERGING MOSTLY EMPTY BLOCKS - BEFORE:\n" << *BB << *DestBB);
466 // If the destination block has a single pred, then this is a trivial edge,
468 if (BasicBlock *SinglePred = DestBB->getSinglePredecessor()) {
469 if (SinglePred != DestBB) {
470 // Remember if SinglePred was the entry block of the function. If so, we
471 // will need to move BB back to the entry position.
472 bool isEntry = SinglePred == &SinglePred->getParent()->getEntryBlock();
473 MergeBasicBlockIntoOnlyPred(DestBB, nullptr);
475 if (isEntry && BB != &BB->getParent()->getEntryBlock())
476 BB->moveBefore(&BB->getParent()->getEntryBlock());
478 DEBUG(dbgs() << "AFTER:\n" << *DestBB << "\n\n\n");
483 // Otherwise, we have multiple predecessors of BB. Update the PHIs in DestBB
484 // to handle the new incoming edges it is about to have.
486 for (BasicBlock::iterator BBI = DestBB->begin();
487 (PN = dyn_cast<PHINode>(BBI)); ++BBI) {
488 // Remove the incoming value for BB, and remember it.
489 Value *InVal = PN->removeIncomingValue(BB, false);
491 // Two options: either the InVal is a phi node defined in BB or it is some
492 // value that dominates BB.
493 PHINode *InValPhi = dyn_cast<PHINode>(InVal);
494 if (InValPhi && InValPhi->getParent() == BB) {
495 // Add all of the input values of the input PHI as inputs of this phi.
496 for (unsigned i = 0, e = InValPhi->getNumIncomingValues(); i != e; ++i)
497 PN->addIncoming(InValPhi->getIncomingValue(i),
498 InValPhi->getIncomingBlock(i));
500 // Otherwise, add one instance of the dominating value for each edge that
501 // we will be adding.
502 if (PHINode *BBPN = dyn_cast<PHINode>(BB->begin())) {
503 for (unsigned i = 0, e = BBPN->getNumIncomingValues(); i != e; ++i)
504 PN->addIncoming(InVal, BBPN->getIncomingBlock(i));
506 for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI)
507 PN->addIncoming(InVal, *PI);
512 // The PHIs are now updated, change everything that refers to BB to use
513 // DestBB and remove BB.
514 BB->replaceAllUsesWith(DestBB);
515 BB->eraseFromParent();
518 DEBUG(dbgs() << "AFTER:\n" << *DestBB << "\n\n\n");
521 // Computes a map of base pointer relocation instructions to corresponding
522 // derived pointer relocation instructions given a vector of all relocate calls
523 static void computeBaseDerivedRelocateMap(
524 const SmallVectorImpl<User *> &AllRelocateCalls,
525 DenseMap<IntrinsicInst *, SmallVector<IntrinsicInst *, 2>> &
527 // Collect information in two maps: one primarily for locating the base object
528 // while filling the second map; the second map is the final structure holding
529 // a mapping between Base and corresponding Derived relocate calls
530 DenseMap<std::pair<unsigned, unsigned>, IntrinsicInst *> RelocateIdxMap;
531 for (auto &U : AllRelocateCalls) {
532 GCRelocateOperands ThisRelocate(U);
533 IntrinsicInst *I = cast<IntrinsicInst>(U);
534 auto K = std::make_pair(ThisRelocate.getBasePtrIndex(),
535 ThisRelocate.getDerivedPtrIndex());
536 RelocateIdxMap.insert(std::make_pair(K, I));
538 for (auto &Item : RelocateIdxMap) {
539 std::pair<unsigned, unsigned> Key = Item.first;
540 if (Key.first == Key.second)
541 // Base relocation: nothing to insert
544 IntrinsicInst *I = Item.second;
545 auto BaseKey = std::make_pair(Key.first, Key.first);
547 // We're iterating over RelocateIdxMap so we cannot modify it.
548 auto MaybeBase = RelocateIdxMap.find(BaseKey);
549 if (MaybeBase == RelocateIdxMap.end())
550 // TODO: We might want to insert a new base object relocate and gep off
551 // that, if there are enough derived object relocates.
554 RelocateInstMap[MaybeBase->second].push_back(I);
558 // Accepts a GEP and extracts the operands into a vector provided they're all
559 // small integer constants
560 static bool getGEPSmallConstantIntOffsetV(GetElementPtrInst *GEP,
561 SmallVectorImpl<Value *> &OffsetV) {
562 for (unsigned i = 1; i < GEP->getNumOperands(); i++) {
563 // Only accept small constant integer operands
564 auto Op = dyn_cast<ConstantInt>(GEP->getOperand(i));
565 if (!Op || Op->getZExtValue() > 20)
569 for (unsigned i = 1; i < GEP->getNumOperands(); i++)
570 OffsetV.push_back(GEP->getOperand(i));
574 // Takes a RelocatedBase (base pointer relocation instruction) and Targets to
575 // replace, computes a replacement, and affects it.
577 simplifyRelocatesOffABase(IntrinsicInst *RelocatedBase,
578 const SmallVectorImpl<IntrinsicInst *> &Targets) {
579 bool MadeChange = false;
580 for (auto &ToReplace : Targets) {
581 GCRelocateOperands MasterRelocate(RelocatedBase);
582 GCRelocateOperands ThisRelocate(ToReplace);
584 assert(ThisRelocate.getBasePtrIndex() == MasterRelocate.getBasePtrIndex() &&
585 "Not relocating a derived object of the original base object");
586 if (ThisRelocate.getBasePtrIndex() == ThisRelocate.getDerivedPtrIndex()) {
587 // A duplicate relocate call. TODO: coalesce duplicates.
591 Value *Base = ThisRelocate.getBasePtr();
592 auto Derived = dyn_cast<GetElementPtrInst>(ThisRelocate.getDerivedPtr());
593 if (!Derived || Derived->getPointerOperand() != Base)
596 SmallVector<Value *, 2> OffsetV;
597 if (!getGEPSmallConstantIntOffsetV(Derived, OffsetV))
600 // Create a Builder and replace the target callsite with a gep
601 assert(RelocatedBase->getNextNode() && "Should always have one since it's not a terminator");
603 // Insert after RelocatedBase
604 IRBuilder<> Builder(RelocatedBase->getNextNode());
605 Builder.SetCurrentDebugLocation(ToReplace->getDebugLoc());
607 // If gc_relocate does not match the actual type, cast it to the right type.
608 // In theory, there must be a bitcast after gc_relocate if the type does not
609 // match, and we should reuse it to get the derived pointer. But it could be
613 // %g1 = call coldcc i8 addrspace(1)* @llvm.experimental.gc.relocate.p1i8(...)
618 // %g2 = call coldcc i8 addrspace(1)* @llvm.experimental.gc.relocate.p1i8(...)
622 // %p1 = phi i8 addrspace(1)* [ %g1, %bb1 ], [ %g2, %bb2 ]
623 // %cast = bitcast i8 addrspace(1)* %p1 in to i32 addrspace(1)*
625 // In this case, we can not find the bitcast any more. So we insert a new bitcast
626 // no matter there is already one or not. In this way, we can handle all cases, and
627 // the extra bitcast should be optimized away in later passes.
628 Instruction *ActualRelocatedBase = RelocatedBase;
629 if (RelocatedBase->getType() != Base->getType()) {
630 ActualRelocatedBase =
631 cast<Instruction>(Builder.CreateBitCast(RelocatedBase, Base->getType()));
633 Value *Replacement = Builder.CreateGEP(
634 Derived->getSourceElementType(), ActualRelocatedBase, makeArrayRef(OffsetV));
635 Instruction *ReplacementInst = cast<Instruction>(Replacement);
636 Replacement->takeName(ToReplace);
637 // If the newly generated derived pointer's type does not match the original derived
638 // pointer's type, cast the new derived pointer to match it. Same reasoning as above.
639 Instruction *ActualReplacement = ReplacementInst;
640 if (ReplacementInst->getType() != ToReplace->getType()) {
642 cast<Instruction>(Builder.CreateBitCast(ReplacementInst, ToReplace->getType()));
644 ToReplace->replaceAllUsesWith(ActualReplacement);
645 ToReplace->eraseFromParent();
655 // %ptr = gep %base + 15
656 // %tok = statepoint (%fun, i32 0, i32 0, i32 0, %base, %ptr)
657 // %base' = relocate(%tok, i32 4, i32 4)
658 // %ptr' = relocate(%tok, i32 4, i32 5)
664 // %ptr = gep %base + 15
665 // %tok = statepoint (%fun, i32 0, i32 0, i32 0, %base, %ptr)
666 // %base' = gc.relocate(%tok, i32 4, i32 4)
667 // %ptr' = gep %base' + 15
669 bool CodeGenPrepare::simplifyOffsetableRelocate(Instruction &I) {
670 bool MadeChange = false;
671 SmallVector<User *, 2> AllRelocateCalls;
673 for (auto *U : I.users())
674 if (isGCRelocate(dyn_cast<Instruction>(U)))
675 // Collect all the relocate calls associated with a statepoint
676 AllRelocateCalls.push_back(U);
678 // We need atleast one base pointer relocation + one derived pointer
679 // relocation to mangle
680 if (AllRelocateCalls.size() < 2)
683 // RelocateInstMap is a mapping from the base relocate instruction to the
684 // corresponding derived relocate instructions
685 DenseMap<IntrinsicInst *, SmallVector<IntrinsicInst *, 2>> RelocateInstMap;
686 computeBaseDerivedRelocateMap(AllRelocateCalls, RelocateInstMap);
687 if (RelocateInstMap.empty())
690 for (auto &Item : RelocateInstMap)
691 // Item.first is the RelocatedBase to offset against
692 // Item.second is the vector of Targets to replace
693 MadeChange = simplifyRelocatesOffABase(Item.first, Item.second);
697 /// SinkCast - Sink the specified cast instruction into its user blocks
698 static bool SinkCast(CastInst *CI) {
699 BasicBlock *DefBB = CI->getParent();
701 /// InsertedCasts - Only insert a cast in each block once.
702 DenseMap<BasicBlock*, CastInst*> InsertedCasts;
704 bool MadeChange = false;
705 for (Value::user_iterator UI = CI->user_begin(), E = CI->user_end();
707 Use &TheUse = UI.getUse();
708 Instruction *User = cast<Instruction>(*UI);
710 // Figure out which BB this cast is used in. For PHI's this is the
711 // appropriate predecessor block.
712 BasicBlock *UserBB = User->getParent();
713 if (PHINode *PN = dyn_cast<PHINode>(User)) {
714 UserBB = PN->getIncomingBlock(TheUse);
717 // Preincrement use iterator so we don't invalidate it.
720 // If this user is in the same block as the cast, don't change the cast.
721 if (UserBB == DefBB) continue;
723 // If we have already inserted a cast into this block, use it.
724 CastInst *&InsertedCast = InsertedCasts[UserBB];
727 BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
729 CastInst::Create(CI->getOpcode(), CI->getOperand(0), CI->getType(), "",
733 // Replace a use of the cast with a use of the new cast.
734 TheUse = InsertedCast;
739 // If we removed all uses, nuke the cast.
740 if (CI->use_empty()) {
741 CI->eraseFromParent();
748 /// OptimizeNoopCopyExpression - If the specified cast instruction is a noop
749 /// copy (e.g. it's casting from one pointer type to another, i32->i8 on PPC),
750 /// sink it into user blocks to reduce the number of virtual
751 /// registers that must be created and coalesced.
753 /// Return true if any changes are made.
755 static bool OptimizeNoopCopyExpression(CastInst *CI, const TargetLowering &TLI){
756 // If this is a noop copy,
757 EVT SrcVT = TLI.getValueType(CI->getOperand(0)->getType());
758 EVT DstVT = TLI.getValueType(CI->getType());
760 // This is an fp<->int conversion?
761 if (SrcVT.isInteger() != DstVT.isInteger())
764 // If this is an extension, it will be a zero or sign extension, which
766 if (SrcVT.bitsLT(DstVT)) return false;
768 // If these values will be promoted, find out what they will be promoted
769 // to. This helps us consider truncates on PPC as noop copies when they
771 if (TLI.getTypeAction(CI->getContext(), SrcVT) ==
772 TargetLowering::TypePromoteInteger)
773 SrcVT = TLI.getTypeToTransformTo(CI->getContext(), SrcVT);
774 if (TLI.getTypeAction(CI->getContext(), DstVT) ==
775 TargetLowering::TypePromoteInteger)
776 DstVT = TLI.getTypeToTransformTo(CI->getContext(), DstVT);
778 // If, after promotion, these are the same types, this is a noop copy.
785 /// CombineUAddWithOverflow - try to combine CI into a call to the
786 /// llvm.uadd.with.overflow intrinsic if possible.
788 /// Return true if any changes were made.
789 static bool CombineUAddWithOverflow(CmpInst *CI) {
793 m_UAddWithOverflow(m_Value(A), m_Value(B), m_Instruction(AddI))))
796 Type *Ty = AddI->getType();
797 if (!isa<IntegerType>(Ty))
800 // We don't want to move around uses of condition values this late, so we we
801 // check if it is legal to create the call to the intrinsic in the basic
802 // block containing the icmp:
804 if (AddI->getParent() != CI->getParent() && !AddI->hasOneUse())
808 // Someday m_UAddWithOverflow may get smarter, but this is a safe assumption
810 if (AddI->hasOneUse())
811 assert(*AddI->user_begin() == CI && "expected!");
814 Module *M = CI->getParent()->getParent()->getParent();
815 Value *F = Intrinsic::getDeclaration(M, Intrinsic::uadd_with_overflow, Ty);
817 auto *InsertPt = AddI->hasOneUse() ? CI : AddI;
819 auto *UAddWithOverflow =
820 CallInst::Create(F, {A, B}, "uadd.overflow", InsertPt);
821 auto *UAdd = ExtractValueInst::Create(UAddWithOverflow, 0, "uadd", InsertPt);
823 ExtractValueInst::Create(UAddWithOverflow, 1, "overflow", InsertPt);
825 CI->replaceAllUsesWith(Overflow);
826 AddI->replaceAllUsesWith(UAdd);
827 CI->eraseFromParent();
828 AddI->eraseFromParent();
832 /// SinkCmpExpression - Sink the given CmpInst into user blocks to reduce
833 /// the number of virtual registers that must be created and coalesced. This is
834 /// a clear win except on targets with multiple condition code registers
835 /// (PowerPC), where it might lose; some adjustment may be wanted there.
837 /// Return true if any changes are made.
838 static bool SinkCmpExpression(CmpInst *CI) {
839 BasicBlock *DefBB = CI->getParent();
841 /// InsertedCmp - Only insert a cmp in each block once.
842 DenseMap<BasicBlock*, CmpInst*> InsertedCmps;
844 bool MadeChange = false;
845 for (Value::user_iterator UI = CI->user_begin(), E = CI->user_end();
847 Use &TheUse = UI.getUse();
848 Instruction *User = cast<Instruction>(*UI);
850 // Preincrement use iterator so we don't invalidate it.
853 // Don't bother for PHI nodes.
854 if (isa<PHINode>(User))
857 // Figure out which BB this cmp is used in.
858 BasicBlock *UserBB = User->getParent();
860 // If this user is in the same block as the cmp, don't change the cmp.
861 if (UserBB == DefBB) continue;
863 // If we have already inserted a cmp into this block, use it.
864 CmpInst *&InsertedCmp = InsertedCmps[UserBB];
867 BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
869 CmpInst::Create(CI->getOpcode(),
870 CI->getPredicate(), CI->getOperand(0),
871 CI->getOperand(1), "", InsertPt);
874 // Replace a use of the cmp with a use of the new cmp.
875 TheUse = InsertedCmp;
880 // If we removed all uses, nuke the cmp.
881 if (CI->use_empty()) {
882 CI->eraseFromParent();
889 static bool OptimizeCmpExpression(CmpInst *CI) {
890 if (SinkCmpExpression(CI))
893 if (CombineUAddWithOverflow(CI))
899 /// isExtractBitsCandidateUse - Check if the candidates could
900 /// be combined with shift instruction, which includes:
901 /// 1. Truncate instruction
902 /// 2. And instruction and the imm is a mask of the low bits:
903 /// imm & (imm+1) == 0
904 static bool isExtractBitsCandidateUse(Instruction *User) {
905 if (!isa<TruncInst>(User)) {
906 if (User->getOpcode() != Instruction::And ||
907 !isa<ConstantInt>(User->getOperand(1)))
910 const APInt &Cimm = cast<ConstantInt>(User->getOperand(1))->getValue();
912 if ((Cimm & (Cimm + 1)).getBoolValue())
918 /// SinkShiftAndTruncate - sink both shift and truncate instruction
919 /// to the use of truncate's BB.
921 SinkShiftAndTruncate(BinaryOperator *ShiftI, Instruction *User, ConstantInt *CI,
922 DenseMap<BasicBlock *, BinaryOperator *> &InsertedShifts,
923 const TargetLowering &TLI) {
924 BasicBlock *UserBB = User->getParent();
925 DenseMap<BasicBlock *, CastInst *> InsertedTruncs;
926 TruncInst *TruncI = dyn_cast<TruncInst>(User);
927 bool MadeChange = false;
929 for (Value::user_iterator TruncUI = TruncI->user_begin(),
930 TruncE = TruncI->user_end();
931 TruncUI != TruncE;) {
933 Use &TruncTheUse = TruncUI.getUse();
934 Instruction *TruncUser = cast<Instruction>(*TruncUI);
935 // Preincrement use iterator so we don't invalidate it.
939 int ISDOpcode = TLI.InstructionOpcodeToISD(TruncUser->getOpcode());
943 // If the use is actually a legal node, there will not be an
944 // implicit truncate.
945 // FIXME: always querying the result type is just an
946 // approximation; some nodes' legality is determined by the
947 // operand or other means. There's no good way to find out though.
948 if (TLI.isOperationLegalOrCustom(
949 ISDOpcode, TLI.getValueType(TruncUser->getType(), true)))
952 // Don't bother for PHI nodes.
953 if (isa<PHINode>(TruncUser))
956 BasicBlock *TruncUserBB = TruncUser->getParent();
958 if (UserBB == TruncUserBB)
961 BinaryOperator *&InsertedShift = InsertedShifts[TruncUserBB];
962 CastInst *&InsertedTrunc = InsertedTruncs[TruncUserBB];
964 if (!InsertedShift && !InsertedTrunc) {
965 BasicBlock::iterator InsertPt = TruncUserBB->getFirstInsertionPt();
967 if (ShiftI->getOpcode() == Instruction::AShr)
969 BinaryOperator::CreateAShr(ShiftI->getOperand(0), CI, "", InsertPt);
972 BinaryOperator::CreateLShr(ShiftI->getOperand(0), CI, "", InsertPt);
975 BasicBlock::iterator TruncInsertPt = TruncUserBB->getFirstInsertionPt();
978 InsertedTrunc = CastInst::Create(TruncI->getOpcode(), InsertedShift,
979 TruncI->getType(), "", TruncInsertPt);
983 TruncTheUse = InsertedTrunc;
989 /// OptimizeExtractBits - sink the shift *right* instruction into user blocks if
990 /// the uses could potentially be combined with this shift instruction and
991 /// generate BitExtract instruction. It will only be applied if the architecture
992 /// supports BitExtract instruction. Here is an example:
994 /// %x.extract.shift = lshr i64 %arg1, 32
996 /// %x.extract.trunc = trunc i64 %x.extract.shift to i16
1000 /// %x.extract.shift.1 = lshr i64 %arg1, 32
1001 /// %x.extract.trunc = trunc i64 %x.extract.shift.1 to i16
1003 /// CodeGen will recoginze the pattern in BB2 and generate BitExtract
1005 /// Return true if any changes are made.
1006 static bool OptimizeExtractBits(BinaryOperator *ShiftI, ConstantInt *CI,
1007 const TargetLowering &TLI) {
1008 BasicBlock *DefBB = ShiftI->getParent();
1010 /// Only insert instructions in each block once.
1011 DenseMap<BasicBlock *, BinaryOperator *> InsertedShifts;
1013 bool shiftIsLegal = TLI.isTypeLegal(TLI.getValueType(ShiftI->getType()));
1015 bool MadeChange = false;
1016 for (Value::user_iterator UI = ShiftI->user_begin(), E = ShiftI->user_end();
1018 Use &TheUse = UI.getUse();
1019 Instruction *User = cast<Instruction>(*UI);
1020 // Preincrement use iterator so we don't invalidate it.
1023 // Don't bother for PHI nodes.
1024 if (isa<PHINode>(User))
1027 if (!isExtractBitsCandidateUse(User))
1030 BasicBlock *UserBB = User->getParent();
1032 if (UserBB == DefBB) {
1033 // If the shift and truncate instruction are in the same BB. The use of
1034 // the truncate(TruncUse) may still introduce another truncate if not
1035 // legal. In this case, we would like to sink both shift and truncate
1036 // instruction to the BB of TruncUse.
1039 // i64 shift.result = lshr i64 opnd, imm
1040 // trunc.result = trunc shift.result to i16
1043 // ----> We will have an implicit truncate here if the architecture does
1044 // not have i16 compare.
1045 // cmp i16 trunc.result, opnd2
1047 if (isa<TruncInst>(User) && shiftIsLegal
1048 // If the type of the truncate is legal, no trucate will be
1049 // introduced in other basic blocks.
1050 && (!TLI.isTypeLegal(TLI.getValueType(User->getType()))))
1052 SinkShiftAndTruncate(ShiftI, User, CI, InsertedShifts, TLI);
1056 // If we have already inserted a shift into this block, use it.
1057 BinaryOperator *&InsertedShift = InsertedShifts[UserBB];
1059 if (!InsertedShift) {
1060 BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
1062 if (ShiftI->getOpcode() == Instruction::AShr)
1064 BinaryOperator::CreateAShr(ShiftI->getOperand(0), CI, "", InsertPt);
1067 BinaryOperator::CreateLShr(ShiftI->getOperand(0), CI, "", InsertPt);
1072 // Replace a use of the shift with a use of the new shift.
1073 TheUse = InsertedShift;
1076 // If we removed all uses, nuke the shift.
1077 if (ShiftI->use_empty())
1078 ShiftI->eraseFromParent();
1083 // ScalarizeMaskedLoad() translates masked load intrinsic, like
1084 // <16 x i32 > @llvm.masked.load( <16 x i32>* %addr, i32 align,
1085 // <16 x i1> %mask, <16 x i32> %passthru)
1086 // to a chain of basic blocks, whith loading element one-by-one if
1087 // the appropriate mask bit is set
1089 // %1 = bitcast i8* %addr to i32*
1090 // %2 = extractelement <16 x i1> %mask, i32 0
1091 // %3 = icmp eq i1 %2, true
1092 // br i1 %3, label %cond.load, label %else
1094 //cond.load: ; preds = %0
1095 // %4 = getelementptr i32* %1, i32 0
1096 // %5 = load i32* %4
1097 // %6 = insertelement <16 x i32> undef, i32 %5, i32 0
1100 //else: ; preds = %0, %cond.load
1101 // %res.phi.else = phi <16 x i32> [ %6, %cond.load ], [ undef, %0 ]
1102 // %7 = extractelement <16 x i1> %mask, i32 1
1103 // %8 = icmp eq i1 %7, true
1104 // br i1 %8, label %cond.load1, label %else2
1106 //cond.load1: ; preds = %else
1107 // %9 = getelementptr i32* %1, i32 1
1108 // %10 = load i32* %9
1109 // %11 = insertelement <16 x i32> %res.phi.else, i32 %10, i32 1
1112 //else2: ; preds = %else, %cond.load1
1113 // %res.phi.else3 = phi <16 x i32> [ %11, %cond.load1 ], [ %res.phi.else, %else ]
1114 // %12 = extractelement <16 x i1> %mask, i32 2
1115 // %13 = icmp eq i1 %12, true
1116 // br i1 %13, label %cond.load4, label %else5
1118 static void ScalarizeMaskedLoad(CallInst *CI) {
1119 Value *Ptr = CI->getArgOperand(0);
1120 Value *Src0 = CI->getArgOperand(3);
1121 Value *Mask = CI->getArgOperand(2);
1122 VectorType *VecType = dyn_cast<VectorType>(CI->getType());
1123 Type *EltTy = VecType->getElementType();
1125 assert(VecType && "Unexpected return type of masked load intrinsic");
1127 IRBuilder<> Builder(CI->getContext());
1128 Instruction *InsertPt = CI;
1129 BasicBlock *IfBlock = CI->getParent();
1130 BasicBlock *CondBlock = nullptr;
1131 BasicBlock *PrevIfBlock = CI->getParent();
1132 Builder.SetInsertPoint(InsertPt);
1134 Builder.SetCurrentDebugLocation(CI->getDebugLoc());
1136 // Bitcast %addr fron i8* to EltTy*
1138 EltTy->getPointerTo(cast<PointerType>(Ptr->getType())->getAddressSpace());
1139 Value *FirstEltPtr = Builder.CreateBitCast(Ptr, NewPtrType);
1140 Value *UndefVal = UndefValue::get(VecType);
1142 // The result vector
1143 Value *VResult = UndefVal;
1145 PHINode *Phi = nullptr;
1146 Value *PrevPhi = UndefVal;
1148 unsigned VectorWidth = VecType->getNumElements();
1149 for (unsigned Idx = 0; Idx < VectorWidth; ++Idx) {
1151 // Fill the "else" block, created in the previous iteration
1153 // %res.phi.else3 = phi <16 x i32> [ %11, %cond.load1 ], [ %res.phi.else, %else ]
1154 // %mask_1 = extractelement <16 x i1> %mask, i32 Idx
1155 // %to_load = icmp eq i1 %mask_1, true
1156 // br i1 %to_load, label %cond.load, label %else
1159 Phi = Builder.CreatePHI(VecType, 2, "res.phi.else");
1160 Phi->addIncoming(VResult, CondBlock);
1161 Phi->addIncoming(PrevPhi, PrevIfBlock);
1166 Value *Predicate = Builder.CreateExtractElement(Mask, Builder.getInt32(Idx));
1167 Value *Cmp = Builder.CreateICmp(ICmpInst::ICMP_EQ, Predicate,
1168 ConstantInt::get(Predicate->getType(), 1));
1170 // Create "cond" block
1172 // %EltAddr = getelementptr i32* %1, i32 0
1173 // %Elt = load i32* %EltAddr
1174 // VResult = insertelement <16 x i32> VResult, i32 %Elt, i32 Idx
1176 CondBlock = IfBlock->splitBasicBlock(InsertPt, "cond.load");
1177 Builder.SetInsertPoint(InsertPt);
1180 Builder.CreateInBoundsGEP(EltTy, FirstEltPtr, Builder.getInt32(Idx));
1181 LoadInst* Load = Builder.CreateLoad(Gep, false);
1182 VResult = Builder.CreateInsertElement(VResult, Load, Builder.getInt32(Idx));
1184 // Create "else" block, fill it in the next iteration
1185 BasicBlock *NewIfBlock = CondBlock->splitBasicBlock(InsertPt, "else");
1186 Builder.SetInsertPoint(InsertPt);
1187 Instruction *OldBr = IfBlock->getTerminator();
1188 BranchInst::Create(CondBlock, NewIfBlock, Cmp, OldBr);
1189 OldBr->eraseFromParent();
1190 PrevIfBlock = IfBlock;
1191 IfBlock = NewIfBlock;
1194 Phi = Builder.CreatePHI(VecType, 2, "res.phi.select");
1195 Phi->addIncoming(VResult, CondBlock);
1196 Phi->addIncoming(PrevPhi, PrevIfBlock);
1197 Value *NewI = Builder.CreateSelect(Mask, Phi, Src0);
1198 CI->replaceAllUsesWith(NewI);
1199 CI->eraseFromParent();
1202 // ScalarizeMaskedStore() translates masked store intrinsic, like
1203 // void @llvm.masked.store(<16 x i32> %src, <16 x i32>* %addr, i32 align,
1205 // to a chain of basic blocks, that stores element one-by-one if
1206 // the appropriate mask bit is set
1208 // %1 = bitcast i8* %addr to i32*
1209 // %2 = extractelement <16 x i1> %mask, i32 0
1210 // %3 = icmp eq i1 %2, true
1211 // br i1 %3, label %cond.store, label %else
1213 // cond.store: ; preds = %0
1214 // %4 = extractelement <16 x i32> %val, i32 0
1215 // %5 = getelementptr i32* %1, i32 0
1216 // store i32 %4, i32* %5
1219 // else: ; preds = %0, %cond.store
1220 // %6 = extractelement <16 x i1> %mask, i32 1
1221 // %7 = icmp eq i1 %6, true
1222 // br i1 %7, label %cond.store1, label %else2
1224 // cond.store1: ; preds = %else
1225 // %8 = extractelement <16 x i32> %val, i32 1
1226 // %9 = getelementptr i32* %1, i32 1
1227 // store i32 %8, i32* %9
1230 static void ScalarizeMaskedStore(CallInst *CI) {
1231 Value *Ptr = CI->getArgOperand(1);
1232 Value *Src = CI->getArgOperand(0);
1233 Value *Mask = CI->getArgOperand(3);
1235 VectorType *VecType = dyn_cast<VectorType>(Src->getType());
1236 Type *EltTy = VecType->getElementType();
1238 assert(VecType && "Unexpected data type in masked store intrinsic");
1240 IRBuilder<> Builder(CI->getContext());
1241 Instruction *InsertPt = CI;
1242 BasicBlock *IfBlock = CI->getParent();
1243 Builder.SetInsertPoint(InsertPt);
1244 Builder.SetCurrentDebugLocation(CI->getDebugLoc());
1246 // Bitcast %addr fron i8* to EltTy*
1248 EltTy->getPointerTo(cast<PointerType>(Ptr->getType())->getAddressSpace());
1249 Value *FirstEltPtr = Builder.CreateBitCast(Ptr, NewPtrType);
1251 unsigned VectorWidth = VecType->getNumElements();
1252 for (unsigned Idx = 0; Idx < VectorWidth; ++Idx) {
1254 // Fill the "else" block, created in the previous iteration
1256 // %mask_1 = extractelement <16 x i1> %mask, i32 Idx
1257 // %to_store = icmp eq i1 %mask_1, true
1258 // br i1 %to_load, label %cond.store, label %else
1260 Value *Predicate = Builder.CreateExtractElement(Mask, Builder.getInt32(Idx));
1261 Value *Cmp = Builder.CreateICmp(ICmpInst::ICMP_EQ, Predicate,
1262 ConstantInt::get(Predicate->getType(), 1));
1264 // Create "cond" block
1266 // %OneElt = extractelement <16 x i32> %Src, i32 Idx
1267 // %EltAddr = getelementptr i32* %1, i32 0
1268 // %store i32 %OneElt, i32* %EltAddr
1270 BasicBlock *CondBlock = IfBlock->splitBasicBlock(InsertPt, "cond.store");
1271 Builder.SetInsertPoint(InsertPt);
1273 Value *OneElt = Builder.CreateExtractElement(Src, Builder.getInt32(Idx));
1275 Builder.CreateInBoundsGEP(EltTy, FirstEltPtr, Builder.getInt32(Idx));
1276 Builder.CreateStore(OneElt, Gep);
1278 // Create "else" block, fill it in the next iteration
1279 BasicBlock *NewIfBlock = CondBlock->splitBasicBlock(InsertPt, "else");
1280 Builder.SetInsertPoint(InsertPt);
1281 Instruction *OldBr = IfBlock->getTerminator();
1282 BranchInst::Create(CondBlock, NewIfBlock, Cmp, OldBr);
1283 OldBr->eraseFromParent();
1284 IfBlock = NewIfBlock;
1286 CI->eraseFromParent();
1289 bool CodeGenPrepare::OptimizeCallInst(CallInst *CI, bool& ModifiedDT) {
1290 BasicBlock *BB = CI->getParent();
1292 // Lower inline assembly if we can.
1293 // If we found an inline asm expession, and if the target knows how to
1294 // lower it to normal LLVM code, do so now.
1295 if (TLI && isa<InlineAsm>(CI->getCalledValue())) {
1296 if (TLI->ExpandInlineAsm(CI)) {
1297 // Avoid invalidating the iterator.
1298 CurInstIterator = BB->begin();
1299 // Avoid processing instructions out of order, which could cause
1300 // reuse before a value is defined.
1304 // Sink address computing for memory operands into the block.
1305 if (OptimizeInlineAsmInst(CI))
1309 const DataLayout *TD = TLI ? TLI->getDataLayout() : nullptr;
1311 // Align the pointer arguments to this call if the target thinks it's a good
1313 unsigned MinSize, PrefAlign;
1314 if (TLI && TD && TLI->shouldAlignPointerArgs(CI, MinSize, PrefAlign)) {
1315 for (auto &Arg : CI->arg_operands()) {
1316 // We want to align both objects whose address is used directly and
1317 // objects whose address is used in casts and GEPs, though it only makes
1318 // sense for GEPs if the offset is a multiple of the desired alignment and
1319 // if size - offset meets the size threshold.
1320 if (!Arg->getType()->isPointerTy())
1322 APInt Offset(TD->getPointerSizeInBits(
1323 cast<PointerType>(Arg->getType())->getAddressSpace()), 0);
1324 Value *Val = Arg->stripAndAccumulateInBoundsConstantOffsets(*TD, Offset);
1325 uint64_t Offset2 = Offset.getLimitedValue();
1326 if ((Offset2 & (PrefAlign-1)) != 0)
1329 if ((AI = dyn_cast<AllocaInst>(Val)) &&
1330 AI->getAlignment() < PrefAlign &&
1331 TD->getTypeAllocSize(AI->getAllocatedType()) >= MinSize + Offset2)
1332 AI->setAlignment(PrefAlign);
1333 // Global variables can only be aligned if they are defined in this
1334 // object (i.e. they are uniquely initialized in this object), and
1335 // over-aligning global variables that have an explicit section is
1338 if ((GV = dyn_cast<GlobalVariable>(Val)) &&
1339 GV->hasUniqueInitializer() &&
1340 !GV->hasSection() &&
1341 GV->getAlignment() < PrefAlign &&
1342 TD->getTypeAllocSize(
1343 GV->getType()->getElementType()) >= MinSize + Offset2)
1344 GV->setAlignment(PrefAlign);
1346 // If this is a memcpy (or similar) then we may be able to improve the
1348 if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(CI)) {
1349 unsigned Align = getKnownAlignment(MI->getDest(), *TD);
1350 if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(MI))
1351 Align = std::min(Align, getKnownAlignment(MTI->getSource(), *TD));
1352 if (Align > MI->getAlignment())
1353 MI->setAlignment(ConstantInt::get(MI->getAlignmentType(), Align));
1357 IntrinsicInst *II = dyn_cast<IntrinsicInst>(CI);
1359 switch (II->getIntrinsicID()) {
1361 case Intrinsic::objectsize: {
1362 // Lower all uses of llvm.objectsize.*
1363 bool Min = (cast<ConstantInt>(II->getArgOperand(1))->getZExtValue() == 1);
1364 Type *ReturnTy = CI->getType();
1365 Constant *RetVal = ConstantInt::get(ReturnTy, Min ? 0 : -1ULL);
1367 // Substituting this can cause recursive simplifications, which can
1368 // invalidate our iterator. Use a WeakVH to hold onto it in case this
1370 WeakVH IterHandle(CurInstIterator);
1372 replaceAndRecursivelySimplify(CI, RetVal,
1375 // If the iterator instruction was recursively deleted, start over at the
1376 // start of the block.
1377 if (IterHandle != CurInstIterator) {
1378 CurInstIterator = BB->begin();
1383 case Intrinsic::masked_load: {
1384 // Scalarize unsupported vector masked load
1385 if (!TTI->isLegalMaskedLoad(CI->getType(), 1)) {
1386 ScalarizeMaskedLoad(CI);
1392 case Intrinsic::masked_store: {
1393 if (!TTI->isLegalMaskedStore(CI->getArgOperand(0)->getType(), 1)) {
1394 ScalarizeMaskedStore(CI);
1403 SmallVector<Value*, 2> PtrOps;
1405 if (TLI->GetAddrModeArguments(II, PtrOps, AccessTy))
1406 while (!PtrOps.empty())
1407 if (OptimizeMemoryInst(II, PtrOps.pop_back_val(), AccessTy))
1412 // From here on out we're working with named functions.
1413 if (!CI->getCalledFunction()) return false;
1415 // Lower all default uses of _chk calls. This is very similar
1416 // to what InstCombineCalls does, but here we are only lowering calls
1417 // to fortified library functions (e.g. __memcpy_chk) that have the default
1418 // "don't know" as the objectsize. Anything else should be left alone.
1419 FortifiedLibCallSimplifier Simplifier(TLInfo, true);
1420 if (Value *V = Simplifier.optimizeCall(CI)) {
1421 CI->replaceAllUsesWith(V);
1422 CI->eraseFromParent();
1428 /// DupRetToEnableTailCallOpts - Look for opportunities to duplicate return
1429 /// instructions to the predecessor to enable tail call optimizations. The
1430 /// case it is currently looking for is:
1433 /// %tmp0 = tail call i32 @f0()
1434 /// br label %return
1436 /// %tmp1 = tail call i32 @f1()
1437 /// br label %return
1439 /// %tmp2 = tail call i32 @f2()
1440 /// br label %return
1442 /// %retval = phi i32 [ %tmp0, %bb0 ], [ %tmp1, %bb1 ], [ %tmp2, %bb2 ]
1450 /// %tmp0 = tail call i32 @f0()
1453 /// %tmp1 = tail call i32 @f1()
1456 /// %tmp2 = tail call i32 @f2()
1459 bool CodeGenPrepare::DupRetToEnableTailCallOpts(BasicBlock *BB) {
1463 ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator());
1467 PHINode *PN = nullptr;
1468 BitCastInst *BCI = nullptr;
1469 Value *V = RI->getReturnValue();
1471 BCI = dyn_cast<BitCastInst>(V);
1473 V = BCI->getOperand(0);
1475 PN = dyn_cast<PHINode>(V);
1480 if (PN && PN->getParent() != BB)
1483 // It's not safe to eliminate the sign / zero extension of the return value.
1484 // See llvm::isInTailCallPosition().
1485 const Function *F = BB->getParent();
1486 AttributeSet CallerAttrs = F->getAttributes();
1487 if (CallerAttrs.hasAttribute(AttributeSet::ReturnIndex, Attribute::ZExt) ||
1488 CallerAttrs.hasAttribute(AttributeSet::ReturnIndex, Attribute::SExt))
1491 // Make sure there are no instructions between the PHI and return, or that the
1492 // return is the first instruction in the block.
1494 BasicBlock::iterator BI = BB->begin();
1495 do { ++BI; } while (isa<DbgInfoIntrinsic>(BI));
1497 // Also skip over the bitcast.
1502 BasicBlock::iterator BI = BB->begin();
1503 while (isa<DbgInfoIntrinsic>(BI)) ++BI;
1508 /// Only dup the ReturnInst if the CallInst is likely to be emitted as a tail
1510 SmallVector<CallInst*, 4> TailCalls;
1512 for (unsigned I = 0, E = PN->getNumIncomingValues(); I != E; ++I) {
1513 CallInst *CI = dyn_cast<CallInst>(PN->getIncomingValue(I));
1514 // Make sure the phi value is indeed produced by the tail call.
1515 if (CI && CI->hasOneUse() && CI->getParent() == PN->getIncomingBlock(I) &&
1516 TLI->mayBeEmittedAsTailCall(CI))
1517 TailCalls.push_back(CI);
1520 SmallPtrSet<BasicBlock*, 4> VisitedBBs;
1521 for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB); PI != PE; ++PI) {
1522 if (!VisitedBBs.insert(*PI).second)
1525 BasicBlock::InstListType &InstList = (*PI)->getInstList();
1526 BasicBlock::InstListType::reverse_iterator RI = InstList.rbegin();
1527 BasicBlock::InstListType::reverse_iterator RE = InstList.rend();
1528 do { ++RI; } while (RI != RE && isa<DbgInfoIntrinsic>(&*RI));
1532 CallInst *CI = dyn_cast<CallInst>(&*RI);
1533 if (CI && CI->use_empty() && TLI->mayBeEmittedAsTailCall(CI))
1534 TailCalls.push_back(CI);
1538 bool Changed = false;
1539 for (unsigned i = 0, e = TailCalls.size(); i != e; ++i) {
1540 CallInst *CI = TailCalls[i];
1543 // Conservatively require the attributes of the call to match those of the
1544 // return. Ignore noalias because it doesn't affect the call sequence.
1545 AttributeSet CalleeAttrs = CS.getAttributes();
1546 if (AttrBuilder(CalleeAttrs, AttributeSet::ReturnIndex).
1547 removeAttribute(Attribute::NoAlias) !=
1548 AttrBuilder(CalleeAttrs, AttributeSet::ReturnIndex).
1549 removeAttribute(Attribute::NoAlias))
1552 // Make sure the call instruction is followed by an unconditional branch to
1553 // the return block.
1554 BasicBlock *CallBB = CI->getParent();
1555 BranchInst *BI = dyn_cast<BranchInst>(CallBB->getTerminator());
1556 if (!BI || !BI->isUnconditional() || BI->getSuccessor(0) != BB)
1559 // Duplicate the return into CallBB.
1560 (void)FoldReturnIntoUncondBranch(RI, BB, CallBB);
1561 ModifiedDT = Changed = true;
1565 // If we eliminated all predecessors of the block, delete the block now.
1566 if (Changed && !BB->hasAddressTaken() && pred_begin(BB) == pred_end(BB))
1567 BB->eraseFromParent();
1572 //===----------------------------------------------------------------------===//
1573 // Memory Optimization
1574 //===----------------------------------------------------------------------===//
1578 /// ExtAddrMode - This is an extended version of TargetLowering::AddrMode
1579 /// which holds actual Value*'s for register values.
1580 struct ExtAddrMode : public TargetLowering::AddrMode {
1583 ExtAddrMode() : BaseReg(nullptr), ScaledReg(nullptr) {}
1584 void print(raw_ostream &OS) const;
1587 bool operator==(const ExtAddrMode& O) const {
1588 return (BaseReg == O.BaseReg) && (ScaledReg == O.ScaledReg) &&
1589 (BaseGV == O.BaseGV) && (BaseOffs == O.BaseOffs) &&
1590 (HasBaseReg == O.HasBaseReg) && (Scale == O.Scale);
1595 static inline raw_ostream &operator<<(raw_ostream &OS, const ExtAddrMode &AM) {
1601 void ExtAddrMode::print(raw_ostream &OS) const {
1602 bool NeedPlus = false;
1605 OS << (NeedPlus ? " + " : "")
1607 BaseGV->printAsOperand(OS, /*PrintType=*/false);
1612 OS << (NeedPlus ? " + " : "")
1618 OS << (NeedPlus ? " + " : "")
1620 BaseReg->printAsOperand(OS, /*PrintType=*/false);
1624 OS << (NeedPlus ? " + " : "")
1626 ScaledReg->printAsOperand(OS, /*PrintType=*/false);
1632 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
1633 void ExtAddrMode::dump() const {
1639 /// \brief This class provides transaction based operation on the IR.
1640 /// Every change made through this class is recorded in the internal state and
1641 /// can be undone (rollback) until commit is called.
1642 class TypePromotionTransaction {
1644 /// \brief This represents the common interface of the individual transaction.
1645 /// Each class implements the logic for doing one specific modification on
1646 /// the IR via the TypePromotionTransaction.
1647 class TypePromotionAction {
1649 /// The Instruction modified.
1653 /// \brief Constructor of the action.
1654 /// The constructor performs the related action on the IR.
1655 TypePromotionAction(Instruction *Inst) : Inst(Inst) {}
1657 virtual ~TypePromotionAction() {}
1659 /// \brief Undo the modification done by this action.
1660 /// When this method is called, the IR must be in the same state as it was
1661 /// before this action was applied.
1662 /// \pre Undoing the action works if and only if the IR is in the exact same
1663 /// state as it was directly after this action was applied.
1664 virtual void undo() = 0;
1666 /// \brief Advocate every change made by this action.
1667 /// When the results on the IR of the action are to be kept, it is important
1668 /// to call this function, otherwise hidden information may be kept forever.
1669 virtual void commit() {
1670 // Nothing to be done, this action is not doing anything.
1674 /// \brief Utility to remember the position of an instruction.
1675 class InsertionHandler {
1676 /// Position of an instruction.
1677 /// Either an instruction:
1678 /// - Is the first in a basic block: BB is used.
1679 /// - Has a previous instructon: PrevInst is used.
1681 Instruction *PrevInst;
1684 /// Remember whether or not the instruction had a previous instruction.
1685 bool HasPrevInstruction;
1688 /// \brief Record the position of \p Inst.
1689 InsertionHandler(Instruction *Inst) {
1690 BasicBlock::iterator It = Inst;
1691 HasPrevInstruction = (It != (Inst->getParent()->begin()));
1692 if (HasPrevInstruction)
1693 Point.PrevInst = --It;
1695 Point.BB = Inst->getParent();
1698 /// \brief Insert \p Inst at the recorded position.
1699 void insert(Instruction *Inst) {
1700 if (HasPrevInstruction) {
1701 if (Inst->getParent())
1702 Inst->removeFromParent();
1703 Inst->insertAfter(Point.PrevInst);
1705 Instruction *Position = Point.BB->getFirstInsertionPt();
1706 if (Inst->getParent())
1707 Inst->moveBefore(Position);
1709 Inst->insertBefore(Position);
1714 /// \brief Move an instruction before another.
1715 class InstructionMoveBefore : public TypePromotionAction {
1716 /// Original position of the instruction.
1717 InsertionHandler Position;
1720 /// \brief Move \p Inst before \p Before.
1721 InstructionMoveBefore(Instruction *Inst, Instruction *Before)
1722 : TypePromotionAction(Inst), Position(Inst) {
1723 DEBUG(dbgs() << "Do: move: " << *Inst << "\nbefore: " << *Before << "\n");
1724 Inst->moveBefore(Before);
1727 /// \brief Move the instruction back to its original position.
1728 void undo() override {
1729 DEBUG(dbgs() << "Undo: moveBefore: " << *Inst << "\n");
1730 Position.insert(Inst);
1734 /// \brief Set the operand of an instruction with a new value.
1735 class OperandSetter : public TypePromotionAction {
1736 /// Original operand of the instruction.
1738 /// Index of the modified instruction.
1742 /// \brief Set \p Idx operand of \p Inst with \p NewVal.
1743 OperandSetter(Instruction *Inst, unsigned Idx, Value *NewVal)
1744 : TypePromotionAction(Inst), Idx(Idx) {
1745 DEBUG(dbgs() << "Do: setOperand: " << Idx << "\n"
1746 << "for:" << *Inst << "\n"
1747 << "with:" << *NewVal << "\n");
1748 Origin = Inst->getOperand(Idx);
1749 Inst->setOperand(Idx, NewVal);
1752 /// \brief Restore the original value of the instruction.
1753 void undo() override {
1754 DEBUG(dbgs() << "Undo: setOperand:" << Idx << "\n"
1755 << "for: " << *Inst << "\n"
1756 << "with: " << *Origin << "\n");
1757 Inst->setOperand(Idx, Origin);
1761 /// \brief Hide the operands of an instruction.
1762 /// Do as if this instruction was not using any of its operands.
1763 class OperandsHider : public TypePromotionAction {
1764 /// The list of original operands.
1765 SmallVector<Value *, 4> OriginalValues;
1768 /// \brief Remove \p Inst from the uses of the operands of \p Inst.
1769 OperandsHider(Instruction *Inst) : TypePromotionAction(Inst) {
1770 DEBUG(dbgs() << "Do: OperandsHider: " << *Inst << "\n");
1771 unsigned NumOpnds = Inst->getNumOperands();
1772 OriginalValues.reserve(NumOpnds);
1773 for (unsigned It = 0; It < NumOpnds; ++It) {
1774 // Save the current operand.
1775 Value *Val = Inst->getOperand(It);
1776 OriginalValues.push_back(Val);
1778 // We could use OperandSetter here, but that would implied an overhead
1779 // that we are not willing to pay.
1780 Inst->setOperand(It, UndefValue::get(Val->getType()));
1784 /// \brief Restore the original list of uses.
1785 void undo() override {
1786 DEBUG(dbgs() << "Undo: OperandsHider: " << *Inst << "\n");
1787 for (unsigned It = 0, EndIt = OriginalValues.size(); It != EndIt; ++It)
1788 Inst->setOperand(It, OriginalValues[It]);
1792 /// \brief Build a truncate instruction.
1793 class TruncBuilder : public TypePromotionAction {
1796 /// \brief Build a truncate instruction of \p Opnd producing a \p Ty
1798 /// trunc Opnd to Ty.
1799 TruncBuilder(Instruction *Opnd, Type *Ty) : TypePromotionAction(Opnd) {
1800 IRBuilder<> Builder(Opnd);
1801 Val = Builder.CreateTrunc(Opnd, Ty, "promoted");
1802 DEBUG(dbgs() << "Do: TruncBuilder: " << *Val << "\n");
1805 /// \brief Get the built value.
1806 Value *getBuiltValue() { return Val; }
1808 /// \brief Remove the built instruction.
1809 void undo() override {
1810 DEBUG(dbgs() << "Undo: TruncBuilder: " << *Val << "\n");
1811 if (Instruction *IVal = dyn_cast<Instruction>(Val))
1812 IVal->eraseFromParent();
1816 /// \brief Build a sign extension instruction.
1817 class SExtBuilder : public TypePromotionAction {
1820 /// \brief Build a sign extension instruction of \p Opnd producing a \p Ty
1822 /// sext Opnd to Ty.
1823 SExtBuilder(Instruction *InsertPt, Value *Opnd, Type *Ty)
1824 : TypePromotionAction(InsertPt) {
1825 IRBuilder<> Builder(InsertPt);
1826 Val = Builder.CreateSExt(Opnd, Ty, "promoted");
1827 DEBUG(dbgs() << "Do: SExtBuilder: " << *Val << "\n");
1830 /// \brief Get the built value.
1831 Value *getBuiltValue() { return Val; }
1833 /// \brief Remove the built instruction.
1834 void undo() override {
1835 DEBUG(dbgs() << "Undo: SExtBuilder: " << *Val << "\n");
1836 if (Instruction *IVal = dyn_cast<Instruction>(Val))
1837 IVal->eraseFromParent();
1841 /// \brief Build a zero extension instruction.
1842 class ZExtBuilder : public TypePromotionAction {
1845 /// \brief Build a zero extension instruction of \p Opnd producing a \p Ty
1847 /// zext Opnd to Ty.
1848 ZExtBuilder(Instruction *InsertPt, Value *Opnd, Type *Ty)
1849 : TypePromotionAction(InsertPt) {
1850 IRBuilder<> Builder(InsertPt);
1851 Val = Builder.CreateZExt(Opnd, Ty, "promoted");
1852 DEBUG(dbgs() << "Do: ZExtBuilder: " << *Val << "\n");
1855 /// \brief Get the built value.
1856 Value *getBuiltValue() { return Val; }
1858 /// \brief Remove the built instruction.
1859 void undo() override {
1860 DEBUG(dbgs() << "Undo: ZExtBuilder: " << *Val << "\n");
1861 if (Instruction *IVal = dyn_cast<Instruction>(Val))
1862 IVal->eraseFromParent();
1866 /// \brief Mutate an instruction to another type.
1867 class TypeMutator : public TypePromotionAction {
1868 /// Record the original type.
1872 /// \brief Mutate the type of \p Inst into \p NewTy.
1873 TypeMutator(Instruction *Inst, Type *NewTy)
1874 : TypePromotionAction(Inst), OrigTy(Inst->getType()) {
1875 DEBUG(dbgs() << "Do: MutateType: " << *Inst << " with " << *NewTy
1877 Inst->mutateType(NewTy);
1880 /// \brief Mutate the instruction back to its original type.
1881 void undo() override {
1882 DEBUG(dbgs() << "Undo: MutateType: " << *Inst << " with " << *OrigTy
1884 Inst->mutateType(OrigTy);
1888 /// \brief Replace the uses of an instruction by another instruction.
1889 class UsesReplacer : public TypePromotionAction {
1890 /// Helper structure to keep track of the replaced uses.
1891 struct InstructionAndIdx {
1892 /// The instruction using the instruction.
1894 /// The index where this instruction is used for Inst.
1896 InstructionAndIdx(Instruction *Inst, unsigned Idx)
1897 : Inst(Inst), Idx(Idx) {}
1900 /// Keep track of the original uses (pair Instruction, Index).
1901 SmallVector<InstructionAndIdx, 4> OriginalUses;
1902 typedef SmallVectorImpl<InstructionAndIdx>::iterator use_iterator;
1905 /// \brief Replace all the use of \p Inst by \p New.
1906 UsesReplacer(Instruction *Inst, Value *New) : TypePromotionAction(Inst) {
1907 DEBUG(dbgs() << "Do: UsersReplacer: " << *Inst << " with " << *New
1909 // Record the original uses.
1910 for (Use &U : Inst->uses()) {
1911 Instruction *UserI = cast<Instruction>(U.getUser());
1912 OriginalUses.push_back(InstructionAndIdx(UserI, U.getOperandNo()));
1914 // Now, we can replace the uses.
1915 Inst->replaceAllUsesWith(New);
1918 /// \brief Reassign the original uses of Inst to Inst.
1919 void undo() override {
1920 DEBUG(dbgs() << "Undo: UsersReplacer: " << *Inst << "\n");
1921 for (use_iterator UseIt = OriginalUses.begin(),
1922 EndIt = OriginalUses.end();
1923 UseIt != EndIt; ++UseIt) {
1924 UseIt->Inst->setOperand(UseIt->Idx, Inst);
1929 /// \brief Remove an instruction from the IR.
1930 class InstructionRemover : public TypePromotionAction {
1931 /// Original position of the instruction.
1932 InsertionHandler Inserter;
1933 /// Helper structure to hide all the link to the instruction. In other
1934 /// words, this helps to do as if the instruction was removed.
1935 OperandsHider Hider;
1936 /// Keep track of the uses replaced, if any.
1937 UsesReplacer *Replacer;
1940 /// \brief Remove all reference of \p Inst and optinally replace all its
1942 /// \pre If !Inst->use_empty(), then New != nullptr
1943 InstructionRemover(Instruction *Inst, Value *New = nullptr)
1944 : TypePromotionAction(Inst), Inserter(Inst), Hider(Inst),
1947 Replacer = new UsesReplacer(Inst, New);
1948 DEBUG(dbgs() << "Do: InstructionRemover: " << *Inst << "\n");
1949 Inst->removeFromParent();
1952 ~InstructionRemover() override { delete Replacer; }
1954 /// \brief Really remove the instruction.
1955 void commit() override { delete Inst; }
1957 /// \brief Resurrect the instruction and reassign it to the proper uses if
1958 /// new value was provided when build this action.
1959 void undo() override {
1960 DEBUG(dbgs() << "Undo: InstructionRemover: " << *Inst << "\n");
1961 Inserter.insert(Inst);
1969 /// Restoration point.
1970 /// The restoration point is a pointer to an action instead of an iterator
1971 /// because the iterator may be invalidated but not the pointer.
1972 typedef const TypePromotionAction *ConstRestorationPt;
1973 /// Advocate every changes made in that transaction.
1975 /// Undo all the changes made after the given point.
1976 void rollback(ConstRestorationPt Point);
1977 /// Get the current restoration point.
1978 ConstRestorationPt getRestorationPoint() const;
1980 /// \name API for IR modification with state keeping to support rollback.
1982 /// Same as Instruction::setOperand.
1983 void setOperand(Instruction *Inst, unsigned Idx, Value *NewVal);
1984 /// Same as Instruction::eraseFromParent.
1985 void eraseInstruction(Instruction *Inst, Value *NewVal = nullptr);
1986 /// Same as Value::replaceAllUsesWith.
1987 void replaceAllUsesWith(Instruction *Inst, Value *New);
1988 /// Same as Value::mutateType.
1989 void mutateType(Instruction *Inst, Type *NewTy);
1990 /// Same as IRBuilder::createTrunc.
1991 Value *createTrunc(Instruction *Opnd, Type *Ty);
1992 /// Same as IRBuilder::createSExt.
1993 Value *createSExt(Instruction *Inst, Value *Opnd, Type *Ty);
1994 /// Same as IRBuilder::createZExt.
1995 Value *createZExt(Instruction *Inst, Value *Opnd, Type *Ty);
1996 /// Same as Instruction::moveBefore.
1997 void moveBefore(Instruction *Inst, Instruction *Before);
2001 /// The ordered list of actions made so far.
2002 SmallVector<std::unique_ptr<TypePromotionAction>, 16> Actions;
2003 typedef SmallVectorImpl<std::unique_ptr<TypePromotionAction>>::iterator CommitPt;
2006 void TypePromotionTransaction::setOperand(Instruction *Inst, unsigned Idx,
2009 make_unique<TypePromotionTransaction::OperandSetter>(Inst, Idx, NewVal));
2012 void TypePromotionTransaction::eraseInstruction(Instruction *Inst,
2015 make_unique<TypePromotionTransaction::InstructionRemover>(Inst, NewVal));
2018 void TypePromotionTransaction::replaceAllUsesWith(Instruction *Inst,
2020 Actions.push_back(make_unique<TypePromotionTransaction::UsesReplacer>(Inst, New));
2023 void TypePromotionTransaction::mutateType(Instruction *Inst, Type *NewTy) {
2024 Actions.push_back(make_unique<TypePromotionTransaction::TypeMutator>(Inst, NewTy));
2027 Value *TypePromotionTransaction::createTrunc(Instruction *Opnd,
2029 std::unique_ptr<TruncBuilder> Ptr(new TruncBuilder(Opnd, Ty));
2030 Value *Val = Ptr->getBuiltValue();
2031 Actions.push_back(std::move(Ptr));
2035 Value *TypePromotionTransaction::createSExt(Instruction *Inst,
2036 Value *Opnd, Type *Ty) {
2037 std::unique_ptr<SExtBuilder> Ptr(new SExtBuilder(Inst, Opnd, Ty));
2038 Value *Val = Ptr->getBuiltValue();
2039 Actions.push_back(std::move(Ptr));
2043 Value *TypePromotionTransaction::createZExt(Instruction *Inst,
2044 Value *Opnd, Type *Ty) {
2045 std::unique_ptr<ZExtBuilder> Ptr(new ZExtBuilder(Inst, Opnd, Ty));
2046 Value *Val = Ptr->getBuiltValue();
2047 Actions.push_back(std::move(Ptr));
2051 void TypePromotionTransaction::moveBefore(Instruction *Inst,
2052 Instruction *Before) {
2054 make_unique<TypePromotionTransaction::InstructionMoveBefore>(Inst, Before));
2057 TypePromotionTransaction::ConstRestorationPt
2058 TypePromotionTransaction::getRestorationPoint() const {
2059 return !Actions.empty() ? Actions.back().get() : nullptr;
2062 void TypePromotionTransaction::commit() {
2063 for (CommitPt It = Actions.begin(), EndIt = Actions.end(); It != EndIt;
2069 void TypePromotionTransaction::rollback(
2070 TypePromotionTransaction::ConstRestorationPt Point) {
2071 while (!Actions.empty() && Point != Actions.back().get()) {
2072 std::unique_ptr<TypePromotionAction> Curr = Actions.pop_back_val();
2077 /// \brief A helper class for matching addressing modes.
2079 /// This encapsulates the logic for matching the target-legal addressing modes.
2080 class AddressingModeMatcher {
2081 SmallVectorImpl<Instruction*> &AddrModeInsts;
2082 const TargetMachine &TM;
2083 const TargetLowering &TLI;
2085 /// AccessTy/MemoryInst - This is the type for the access (e.g. double) and
2086 /// the memory instruction that we're computing this address for.
2088 Instruction *MemoryInst;
2090 /// AddrMode - This is the addressing mode that we're building up. This is
2091 /// part of the return value of this addressing mode matching stuff.
2092 ExtAddrMode &AddrMode;
2094 /// The truncate instruction inserted by other CodeGenPrepare optimizations.
2095 const SetOfInstrs &InsertedTruncs;
2096 /// A map from the instructions to their type before promotion.
2097 InstrToOrigTy &PromotedInsts;
2098 /// The ongoing transaction where every action should be registered.
2099 TypePromotionTransaction &TPT;
2101 /// IgnoreProfitability - This is set to true when we should not do
2102 /// profitability checks. When true, IsProfitableToFoldIntoAddressingMode
2103 /// always returns true.
2104 bool IgnoreProfitability;
2106 AddressingModeMatcher(SmallVectorImpl<Instruction *> &AMI,
2107 const TargetMachine &TM, Type *AT, Instruction *MI,
2108 ExtAddrMode &AM, const SetOfInstrs &InsertedTruncs,
2109 InstrToOrigTy &PromotedInsts,
2110 TypePromotionTransaction &TPT)
2111 : AddrModeInsts(AMI), TM(TM),
2112 TLI(*TM.getSubtargetImpl(*MI->getParent()->getParent())
2113 ->getTargetLowering()),
2114 AccessTy(AT), MemoryInst(MI), AddrMode(AM),
2115 InsertedTruncs(InsertedTruncs), PromotedInsts(PromotedInsts), TPT(TPT) {
2116 IgnoreProfitability = false;
2120 /// Match - Find the maximal addressing mode that a load/store of V can fold,
2121 /// give an access type of AccessTy. This returns a list of involved
2122 /// instructions in AddrModeInsts.
2123 /// \p InsertedTruncs The truncate instruction inserted by other
2126 /// \p PromotedInsts maps the instructions to their type before promotion.
2127 /// \p The ongoing transaction where every action should be registered.
2128 static ExtAddrMode Match(Value *V, Type *AccessTy,
2129 Instruction *MemoryInst,
2130 SmallVectorImpl<Instruction*> &AddrModeInsts,
2131 const TargetMachine &TM,
2132 const SetOfInstrs &InsertedTruncs,
2133 InstrToOrigTy &PromotedInsts,
2134 TypePromotionTransaction &TPT) {
2137 bool Success = AddressingModeMatcher(AddrModeInsts, TM, AccessTy,
2138 MemoryInst, Result, InsertedTruncs,
2139 PromotedInsts, TPT).MatchAddr(V, 0);
2140 (void)Success; assert(Success && "Couldn't select *anything*?");
2144 bool MatchScaledValue(Value *ScaleReg, int64_t Scale, unsigned Depth);
2145 bool MatchAddr(Value *V, unsigned Depth);
2146 bool MatchOperationAddr(User *Operation, unsigned Opcode, unsigned Depth,
2147 bool *MovedAway = nullptr);
2148 bool IsProfitableToFoldIntoAddressingMode(Instruction *I,
2149 ExtAddrMode &AMBefore,
2150 ExtAddrMode &AMAfter);
2151 bool ValueAlreadyLiveAtInst(Value *Val, Value *KnownLive1, Value *KnownLive2);
2152 bool IsPromotionProfitable(unsigned NewCost, unsigned OldCost,
2153 Value *PromotedOperand) const;
2156 /// MatchScaledValue - Try adding ScaleReg*Scale to the current addressing mode.
2157 /// Return true and update AddrMode if this addr mode is legal for the target,
2159 bool AddressingModeMatcher::MatchScaledValue(Value *ScaleReg, int64_t Scale,
2161 // If Scale is 1, then this is the same as adding ScaleReg to the addressing
2162 // mode. Just process that directly.
2164 return MatchAddr(ScaleReg, Depth);
2166 // If the scale is 0, it takes nothing to add this.
2170 // If we already have a scale of this value, we can add to it, otherwise, we
2171 // need an available scale field.
2172 if (AddrMode.Scale != 0 && AddrMode.ScaledReg != ScaleReg)
2175 ExtAddrMode TestAddrMode = AddrMode;
2177 // Add scale to turn X*4+X*3 -> X*7. This could also do things like
2178 // [A+B + A*7] -> [B+A*8].
2179 TestAddrMode.Scale += Scale;
2180 TestAddrMode.ScaledReg = ScaleReg;
2182 // If the new address isn't legal, bail out.
2183 if (!TLI.isLegalAddressingMode(TestAddrMode, AccessTy))
2186 // It was legal, so commit it.
2187 AddrMode = TestAddrMode;
2189 // Okay, we decided that we can add ScaleReg+Scale to AddrMode. Check now
2190 // to see if ScaleReg is actually X+C. If so, we can turn this into adding
2191 // X*Scale + C*Scale to addr mode.
2192 ConstantInt *CI = nullptr; Value *AddLHS = nullptr;
2193 if (isa<Instruction>(ScaleReg) && // not a constant expr.
2194 match(ScaleReg, m_Add(m_Value(AddLHS), m_ConstantInt(CI)))) {
2195 TestAddrMode.ScaledReg = AddLHS;
2196 TestAddrMode.BaseOffs += CI->getSExtValue()*TestAddrMode.Scale;
2198 // If this addressing mode is legal, commit it and remember that we folded
2199 // this instruction.
2200 if (TLI.isLegalAddressingMode(TestAddrMode, AccessTy)) {
2201 AddrModeInsts.push_back(cast<Instruction>(ScaleReg));
2202 AddrMode = TestAddrMode;
2207 // Otherwise, not (x+c)*scale, just return what we have.
2211 /// MightBeFoldableInst - This is a little filter, which returns true if an
2212 /// addressing computation involving I might be folded into a load/store
2213 /// accessing it. This doesn't need to be perfect, but needs to accept at least
2214 /// the set of instructions that MatchOperationAddr can.
2215 static bool MightBeFoldableInst(Instruction *I) {
2216 switch (I->getOpcode()) {
2217 case Instruction::BitCast:
2218 case Instruction::AddrSpaceCast:
2219 // Don't touch identity bitcasts.
2220 if (I->getType() == I->getOperand(0)->getType())
2222 return I->getType()->isPointerTy() || I->getType()->isIntegerTy();
2223 case Instruction::PtrToInt:
2224 // PtrToInt is always a noop, as we know that the int type is pointer sized.
2226 case Instruction::IntToPtr:
2227 // We know the input is intptr_t, so this is foldable.
2229 case Instruction::Add:
2231 case Instruction::Mul:
2232 case Instruction::Shl:
2233 // Can only handle X*C and X << C.
2234 return isa<ConstantInt>(I->getOperand(1));
2235 case Instruction::GetElementPtr:
2242 /// \brief Check whether or not \p Val is a legal instruction for \p TLI.
2243 /// \note \p Val is assumed to be the product of some type promotion.
2244 /// Therefore if \p Val has an undefined state in \p TLI, this is assumed
2245 /// to be legal, as the non-promoted value would have had the same state.
2246 static bool isPromotedInstructionLegal(const TargetLowering &TLI, Value *Val) {
2247 Instruction *PromotedInst = dyn_cast<Instruction>(Val);
2250 int ISDOpcode = TLI.InstructionOpcodeToISD(PromotedInst->getOpcode());
2251 // If the ISDOpcode is undefined, it was undefined before the promotion.
2254 // Otherwise, check if the promoted instruction is legal or not.
2255 return TLI.isOperationLegalOrCustom(
2256 ISDOpcode, TLI.getValueType(PromotedInst->getType()));
2259 /// \brief Hepler class to perform type promotion.
2260 class TypePromotionHelper {
2261 /// \brief Utility function to check whether or not a sign or zero extension
2262 /// of \p Inst with \p ConsideredExtType can be moved through \p Inst by
2263 /// either using the operands of \p Inst or promoting \p Inst.
2264 /// The type of the extension is defined by \p IsSExt.
2265 /// In other words, check if:
2266 /// ext (Ty Inst opnd1 opnd2 ... opndN) to ConsideredExtType.
2267 /// #1 Promotion applies:
2268 /// ConsideredExtType Inst (ext opnd1 to ConsideredExtType, ...).
2269 /// #2 Operand reuses:
2270 /// ext opnd1 to ConsideredExtType.
2271 /// \p PromotedInsts maps the instructions to their type before promotion.
2272 static bool canGetThrough(const Instruction *Inst, Type *ConsideredExtType,
2273 const InstrToOrigTy &PromotedInsts, bool IsSExt);
2275 /// \brief Utility function to determine if \p OpIdx should be promoted when
2276 /// promoting \p Inst.
2277 static bool shouldExtOperand(const Instruction *Inst, int OpIdx) {
2278 if (isa<SelectInst>(Inst) && OpIdx == 0)
2283 /// \brief Utility function to promote the operand of \p Ext when this
2284 /// operand is a promotable trunc or sext or zext.
2285 /// \p PromotedInsts maps the instructions to their type before promotion.
2286 /// \p CreatedInstsCost[out] contains the cost of all instructions
2287 /// created to promote the operand of Ext.
2288 /// Newly added extensions are inserted in \p Exts.
2289 /// Newly added truncates are inserted in \p Truncs.
2290 /// Should never be called directly.
2291 /// \return The promoted value which is used instead of Ext.
2292 static Value *promoteOperandForTruncAndAnyExt(
2293 Instruction *Ext, TypePromotionTransaction &TPT,
2294 InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
2295 SmallVectorImpl<Instruction *> *Exts,
2296 SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI);
2298 /// \brief Utility function to promote the operand of \p Ext when this
2299 /// operand is promotable and is not a supported trunc or sext.
2300 /// \p PromotedInsts maps the instructions to their type before promotion.
2301 /// \p CreatedInstsCost[out] contains the cost of all the instructions
2302 /// created to promote the operand of Ext.
2303 /// Newly added extensions are inserted in \p Exts.
2304 /// Newly added truncates are inserted in \p Truncs.
2305 /// Should never be called directly.
2306 /// \return The promoted value which is used instead of Ext.
2307 static Value *promoteOperandForOther(Instruction *Ext,
2308 TypePromotionTransaction &TPT,
2309 InstrToOrigTy &PromotedInsts,
2310 unsigned &CreatedInstsCost,
2311 SmallVectorImpl<Instruction *> *Exts,
2312 SmallVectorImpl<Instruction *> *Truncs,
2313 const TargetLowering &TLI, bool IsSExt);
2315 /// \see promoteOperandForOther.
2316 static Value *signExtendOperandForOther(
2317 Instruction *Ext, TypePromotionTransaction &TPT,
2318 InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
2319 SmallVectorImpl<Instruction *> *Exts,
2320 SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI) {
2321 return promoteOperandForOther(Ext, TPT, PromotedInsts, CreatedInstsCost,
2322 Exts, Truncs, TLI, true);
2325 /// \see promoteOperandForOther.
2326 static Value *zeroExtendOperandForOther(
2327 Instruction *Ext, TypePromotionTransaction &TPT,
2328 InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
2329 SmallVectorImpl<Instruction *> *Exts,
2330 SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI) {
2331 return promoteOperandForOther(Ext, TPT, PromotedInsts, CreatedInstsCost,
2332 Exts, Truncs, TLI, false);
2336 /// Type for the utility function that promotes the operand of Ext.
2337 typedef Value *(*Action)(Instruction *Ext, TypePromotionTransaction &TPT,
2338 InstrToOrigTy &PromotedInsts,
2339 unsigned &CreatedInstsCost,
2340 SmallVectorImpl<Instruction *> *Exts,
2341 SmallVectorImpl<Instruction *> *Truncs,
2342 const TargetLowering &TLI);
2343 /// \brief Given a sign/zero extend instruction \p Ext, return the approriate
2344 /// action to promote the operand of \p Ext instead of using Ext.
2345 /// \return NULL if no promotable action is possible with the current
2347 /// \p InsertedTruncs keeps track of all the truncate instructions inserted by
2348 /// the others CodeGenPrepare optimizations. This information is important
2349 /// because we do not want to promote these instructions as CodeGenPrepare
2350 /// will reinsert them later. Thus creating an infinite loop: create/remove.
2351 /// \p PromotedInsts maps the instructions to their type before promotion.
2352 static Action getAction(Instruction *Ext, const SetOfInstrs &InsertedTruncs,
2353 const TargetLowering &TLI,
2354 const InstrToOrigTy &PromotedInsts);
2357 bool TypePromotionHelper::canGetThrough(const Instruction *Inst,
2358 Type *ConsideredExtType,
2359 const InstrToOrigTy &PromotedInsts,
2361 // The promotion helper does not know how to deal with vector types yet.
2362 // To be able to fix that, we would need to fix the places where we
2363 // statically extend, e.g., constants and such.
2364 if (Inst->getType()->isVectorTy())
2367 // We can always get through zext.
2368 if (isa<ZExtInst>(Inst))
2371 // sext(sext) is ok too.
2372 if (IsSExt && isa<SExtInst>(Inst))
2375 // We can get through binary operator, if it is legal. In other words, the
2376 // binary operator must have a nuw or nsw flag.
2377 const BinaryOperator *BinOp = dyn_cast<BinaryOperator>(Inst);
2378 if (BinOp && isa<OverflowingBinaryOperator>(BinOp) &&
2379 ((!IsSExt && BinOp->hasNoUnsignedWrap()) ||
2380 (IsSExt && BinOp->hasNoSignedWrap())))
2383 // Check if we can do the following simplification.
2384 // ext(trunc(opnd)) --> ext(opnd)
2385 if (!isa<TruncInst>(Inst))
2388 Value *OpndVal = Inst->getOperand(0);
2389 // Check if we can use this operand in the extension.
2390 // If the type is larger than the result type of the extension,
2392 if (!OpndVal->getType()->isIntegerTy() ||
2393 OpndVal->getType()->getIntegerBitWidth() >
2394 ConsideredExtType->getIntegerBitWidth())
2397 // If the operand of the truncate is not an instruction, we will not have
2398 // any information on the dropped bits.
2399 // (Actually we could for constant but it is not worth the extra logic).
2400 Instruction *Opnd = dyn_cast<Instruction>(OpndVal);
2404 // Check if the source of the type is narrow enough.
2405 // I.e., check that trunc just drops extended bits of the same kind of
2407 // #1 get the type of the operand and check the kind of the extended bits.
2408 const Type *OpndType;
2409 InstrToOrigTy::const_iterator It = PromotedInsts.find(Opnd);
2410 if (It != PromotedInsts.end() && It->second.IsSExt == IsSExt)
2411 OpndType = It->second.Ty;
2412 else if ((IsSExt && isa<SExtInst>(Opnd)) || (!IsSExt && isa<ZExtInst>(Opnd)))
2413 OpndType = Opnd->getOperand(0)->getType();
2417 // #2 check that the truncate just drop extended bits.
2418 if (Inst->getType()->getIntegerBitWidth() >= OpndType->getIntegerBitWidth())
2424 TypePromotionHelper::Action TypePromotionHelper::getAction(
2425 Instruction *Ext, const SetOfInstrs &InsertedTruncs,
2426 const TargetLowering &TLI, const InstrToOrigTy &PromotedInsts) {
2427 assert((isa<SExtInst>(Ext) || isa<ZExtInst>(Ext)) &&
2428 "Unexpected instruction type");
2429 Instruction *ExtOpnd = dyn_cast<Instruction>(Ext->getOperand(0));
2430 Type *ExtTy = Ext->getType();
2431 bool IsSExt = isa<SExtInst>(Ext);
2432 // If the operand of the extension is not an instruction, we cannot
2434 // If it, check we can get through.
2435 if (!ExtOpnd || !canGetThrough(ExtOpnd, ExtTy, PromotedInsts, IsSExt))
2438 // Do not promote if the operand has been added by codegenprepare.
2439 // Otherwise, it means we are undoing an optimization that is likely to be
2440 // redone, thus causing potential infinite loop.
2441 if (isa<TruncInst>(ExtOpnd) && InsertedTruncs.count(ExtOpnd))
2444 // SExt or Trunc instructions.
2445 // Return the related handler.
2446 if (isa<SExtInst>(ExtOpnd) || isa<TruncInst>(ExtOpnd) ||
2447 isa<ZExtInst>(ExtOpnd))
2448 return promoteOperandForTruncAndAnyExt;
2450 // Regular instruction.
2451 // Abort early if we will have to insert non-free instructions.
2452 if (!ExtOpnd->hasOneUse() && !TLI.isTruncateFree(ExtTy, ExtOpnd->getType()))
2454 return IsSExt ? signExtendOperandForOther : zeroExtendOperandForOther;
2457 Value *TypePromotionHelper::promoteOperandForTruncAndAnyExt(
2458 llvm::Instruction *SExt, TypePromotionTransaction &TPT,
2459 InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
2460 SmallVectorImpl<Instruction *> *Exts,
2461 SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI) {
2462 // By construction, the operand of SExt is an instruction. Otherwise we cannot
2463 // get through it and this method should not be called.
2464 Instruction *SExtOpnd = cast<Instruction>(SExt->getOperand(0));
2465 Value *ExtVal = SExt;
2466 bool HasMergedNonFreeExt = false;
2467 if (isa<ZExtInst>(SExtOpnd)) {
2468 // Replace s|zext(zext(opnd))
2470 HasMergedNonFreeExt = !TLI.isExtFree(SExtOpnd);
2472 TPT.createZExt(SExt, SExtOpnd->getOperand(0), SExt->getType());
2473 TPT.replaceAllUsesWith(SExt, ZExt);
2474 TPT.eraseInstruction(SExt);
2477 // Replace z|sext(trunc(opnd)) or sext(sext(opnd))
2479 TPT.setOperand(SExt, 0, SExtOpnd->getOperand(0));
2481 CreatedInstsCost = 0;
2483 // Remove dead code.
2484 if (SExtOpnd->use_empty())
2485 TPT.eraseInstruction(SExtOpnd);
2487 // Check if the extension is still needed.
2488 Instruction *ExtInst = dyn_cast<Instruction>(ExtVal);
2489 if (!ExtInst || ExtInst->getType() != ExtInst->getOperand(0)->getType()) {
2492 Exts->push_back(ExtInst);
2493 CreatedInstsCost = !TLI.isExtFree(ExtInst) && !HasMergedNonFreeExt;
2498 // At this point we have: ext ty opnd to ty.
2499 // Reassign the uses of ExtInst to the opnd and remove ExtInst.
2500 Value *NextVal = ExtInst->getOperand(0);
2501 TPT.eraseInstruction(ExtInst, NextVal);
2505 Value *TypePromotionHelper::promoteOperandForOther(
2506 Instruction *Ext, TypePromotionTransaction &TPT,
2507 InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
2508 SmallVectorImpl<Instruction *> *Exts,
2509 SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI,
2511 // By construction, the operand of Ext is an instruction. Otherwise we cannot
2512 // get through it and this method should not be called.
2513 Instruction *ExtOpnd = cast<Instruction>(Ext->getOperand(0));
2514 CreatedInstsCost = 0;
2515 if (!ExtOpnd->hasOneUse()) {
2516 // ExtOpnd will be promoted.
2517 // All its uses, but Ext, will need to use a truncated value of the
2518 // promoted version.
2519 // Create the truncate now.
2520 Value *Trunc = TPT.createTrunc(Ext, ExtOpnd->getType());
2521 if (Instruction *ITrunc = dyn_cast<Instruction>(Trunc)) {
2522 ITrunc->removeFromParent();
2523 // Insert it just after the definition.
2524 ITrunc->insertAfter(ExtOpnd);
2526 Truncs->push_back(ITrunc);
2529 TPT.replaceAllUsesWith(ExtOpnd, Trunc);
2530 // Restore the operand of Ext (which has been replace by the previous call
2531 // to replaceAllUsesWith) to avoid creating a cycle trunc <-> sext.
2532 TPT.setOperand(Ext, 0, ExtOpnd);
2535 // Get through the Instruction:
2536 // 1. Update its type.
2537 // 2. Replace the uses of Ext by Inst.
2538 // 3. Extend each operand that needs to be extended.
2540 // Remember the original type of the instruction before promotion.
2541 // This is useful to know that the high bits are sign extended bits.
2542 PromotedInsts.insert(std::pair<Instruction *, TypeIsSExt>(
2543 ExtOpnd, TypeIsSExt(ExtOpnd->getType(), IsSExt)));
2545 TPT.mutateType(ExtOpnd, Ext->getType());
2547 TPT.replaceAllUsesWith(Ext, ExtOpnd);
2549 Instruction *ExtForOpnd = Ext;
2551 DEBUG(dbgs() << "Propagate Ext to operands\n");
2552 for (int OpIdx = 0, EndOpIdx = ExtOpnd->getNumOperands(); OpIdx != EndOpIdx;
2554 DEBUG(dbgs() << "Operand:\n" << *(ExtOpnd->getOperand(OpIdx)) << '\n');
2555 if (ExtOpnd->getOperand(OpIdx)->getType() == Ext->getType() ||
2556 !shouldExtOperand(ExtOpnd, OpIdx)) {
2557 DEBUG(dbgs() << "No need to propagate\n");
2560 // Check if we can statically extend the operand.
2561 Value *Opnd = ExtOpnd->getOperand(OpIdx);
2562 if (const ConstantInt *Cst = dyn_cast<ConstantInt>(Opnd)) {
2563 DEBUG(dbgs() << "Statically extend\n");
2564 unsigned BitWidth = Ext->getType()->getIntegerBitWidth();
2565 APInt CstVal = IsSExt ? Cst->getValue().sext(BitWidth)
2566 : Cst->getValue().zext(BitWidth);
2567 TPT.setOperand(ExtOpnd, OpIdx, ConstantInt::get(Ext->getType(), CstVal));
2570 // UndefValue are typed, so we have to statically sign extend them.
2571 if (isa<UndefValue>(Opnd)) {
2572 DEBUG(dbgs() << "Statically extend\n");
2573 TPT.setOperand(ExtOpnd, OpIdx, UndefValue::get(Ext->getType()));
2577 // Otherwise we have to explicity sign extend the operand.
2578 // Check if Ext was reused to extend an operand.
2580 // If yes, create a new one.
2581 DEBUG(dbgs() << "More operands to ext\n");
2582 Value *ValForExtOpnd = IsSExt ? TPT.createSExt(Ext, Opnd, Ext->getType())
2583 : TPT.createZExt(Ext, Opnd, Ext->getType());
2584 if (!isa<Instruction>(ValForExtOpnd)) {
2585 TPT.setOperand(ExtOpnd, OpIdx, ValForExtOpnd);
2588 ExtForOpnd = cast<Instruction>(ValForExtOpnd);
2591 Exts->push_back(ExtForOpnd);
2592 TPT.setOperand(ExtForOpnd, 0, Opnd);
2594 // Move the sign extension before the insertion point.
2595 TPT.moveBefore(ExtForOpnd, ExtOpnd);
2596 TPT.setOperand(ExtOpnd, OpIdx, ExtForOpnd);
2597 CreatedInstsCost += !TLI.isExtFree(ExtForOpnd);
2598 // If more sext are required, new instructions will have to be created.
2599 ExtForOpnd = nullptr;
2601 if (ExtForOpnd == Ext) {
2602 DEBUG(dbgs() << "Extension is useless now\n");
2603 TPT.eraseInstruction(Ext);
2608 /// IsPromotionProfitable - Check whether or not promoting an instruction
2609 /// to a wider type was profitable.
2610 /// \p NewCost gives the cost of extension instructions created by the
2612 /// \p OldCost gives the cost of extension instructions before the promotion
2613 /// plus the number of instructions that have been
2614 /// matched in the addressing mode the promotion.
2615 /// \p PromotedOperand is the value that has been promoted.
2616 /// \return True if the promotion is profitable, false otherwise.
2617 bool AddressingModeMatcher::IsPromotionProfitable(
2618 unsigned NewCost, unsigned OldCost, Value *PromotedOperand) const {
2619 DEBUG(dbgs() << "OldCost: " << OldCost << "\tNewCost: " << NewCost << '\n');
2620 // The cost of the new extensions is greater than the cost of the
2621 // old extension plus what we folded.
2622 // This is not profitable.
2623 if (NewCost > OldCost)
2625 if (NewCost < OldCost)
2627 // The promotion is neutral but it may help folding the sign extension in
2628 // loads for instance.
2629 // Check that we did not create an illegal instruction.
2630 return isPromotedInstructionLegal(TLI, PromotedOperand);
2633 /// MatchOperationAddr - Given an instruction or constant expr, see if we can
2634 /// fold the operation into the addressing mode. If so, update the addressing
2635 /// mode and return true, otherwise return false without modifying AddrMode.
2636 /// If \p MovedAway is not NULL, it contains the information of whether or
2637 /// not AddrInst has to be folded into the addressing mode on success.
2638 /// If \p MovedAway == true, \p AddrInst will not be part of the addressing
2639 /// because it has been moved away.
2640 /// Thus AddrInst must not be added in the matched instructions.
2641 /// This state can happen when AddrInst is a sext, since it may be moved away.
2642 /// Therefore, AddrInst may not be valid when MovedAway is true and it must
2643 /// not be referenced anymore.
2644 bool AddressingModeMatcher::MatchOperationAddr(User *AddrInst, unsigned Opcode,
2647 // Avoid exponential behavior on extremely deep expression trees.
2648 if (Depth >= 5) return false;
2650 // By default, all matched instructions stay in place.
2655 case Instruction::PtrToInt:
2656 // PtrToInt is always a noop, as we know that the int type is pointer sized.
2657 return MatchAddr(AddrInst->getOperand(0), Depth);
2658 case Instruction::IntToPtr:
2659 // This inttoptr is a no-op if the integer type is pointer sized.
2660 if (TLI.getValueType(AddrInst->getOperand(0)->getType()) ==
2661 TLI.getPointerTy(AddrInst->getType()->getPointerAddressSpace()))
2662 return MatchAddr(AddrInst->getOperand(0), Depth);
2664 case Instruction::BitCast:
2665 case Instruction::AddrSpaceCast:
2666 // BitCast is always a noop, and we can handle it as long as it is
2667 // int->int or pointer->pointer (we don't want int<->fp or something).
2668 if ((AddrInst->getOperand(0)->getType()->isPointerTy() ||
2669 AddrInst->getOperand(0)->getType()->isIntegerTy()) &&
2670 // Don't touch identity bitcasts. These were probably put here by LSR,
2671 // and we don't want to mess around with them. Assume it knows what it
2673 AddrInst->getOperand(0)->getType() != AddrInst->getType())
2674 return MatchAddr(AddrInst->getOperand(0), Depth);
2676 case Instruction::Add: {
2677 // Check to see if we can merge in the RHS then the LHS. If so, we win.
2678 ExtAddrMode BackupAddrMode = AddrMode;
2679 unsigned OldSize = AddrModeInsts.size();
2680 // Start a transaction at this point.
2681 // The LHS may match but not the RHS.
2682 // Therefore, we need a higher level restoration point to undo partially
2683 // matched operation.
2684 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
2685 TPT.getRestorationPoint();
2687 if (MatchAddr(AddrInst->getOperand(1), Depth+1) &&
2688 MatchAddr(AddrInst->getOperand(0), Depth+1))
2691 // Restore the old addr mode info.
2692 AddrMode = BackupAddrMode;
2693 AddrModeInsts.resize(OldSize);
2694 TPT.rollback(LastKnownGood);
2696 // Otherwise this was over-aggressive. Try merging in the LHS then the RHS.
2697 if (MatchAddr(AddrInst->getOperand(0), Depth+1) &&
2698 MatchAddr(AddrInst->getOperand(1), Depth+1))
2701 // Otherwise we definitely can't merge the ADD in.
2702 AddrMode = BackupAddrMode;
2703 AddrModeInsts.resize(OldSize);
2704 TPT.rollback(LastKnownGood);
2707 //case Instruction::Or:
2708 // TODO: We can handle "Or Val, Imm" iff this OR is equivalent to an ADD.
2710 case Instruction::Mul:
2711 case Instruction::Shl: {
2712 // Can only handle X*C and X << C.
2713 ConstantInt *RHS = dyn_cast<ConstantInt>(AddrInst->getOperand(1));
2716 int64_t Scale = RHS->getSExtValue();
2717 if (Opcode == Instruction::Shl)
2718 Scale = 1LL << Scale;
2720 return MatchScaledValue(AddrInst->getOperand(0), Scale, Depth);
2722 case Instruction::GetElementPtr: {
2723 // Scan the GEP. We check it if it contains constant offsets and at most
2724 // one variable offset.
2725 int VariableOperand = -1;
2726 unsigned VariableScale = 0;
2728 int64_t ConstantOffset = 0;
2729 const DataLayout *TD = TLI.getDataLayout();
2730 gep_type_iterator GTI = gep_type_begin(AddrInst);
2731 for (unsigned i = 1, e = AddrInst->getNumOperands(); i != e; ++i, ++GTI) {
2732 if (StructType *STy = dyn_cast<StructType>(*GTI)) {
2733 const StructLayout *SL = TD->getStructLayout(STy);
2735 cast<ConstantInt>(AddrInst->getOperand(i))->getZExtValue();
2736 ConstantOffset += SL->getElementOffset(Idx);
2738 uint64_t TypeSize = TD->getTypeAllocSize(GTI.getIndexedType());
2739 if (ConstantInt *CI = dyn_cast<ConstantInt>(AddrInst->getOperand(i))) {
2740 ConstantOffset += CI->getSExtValue()*TypeSize;
2741 } else if (TypeSize) { // Scales of zero don't do anything.
2742 // We only allow one variable index at the moment.
2743 if (VariableOperand != -1)
2746 // Remember the variable index.
2747 VariableOperand = i;
2748 VariableScale = TypeSize;
2753 // A common case is for the GEP to only do a constant offset. In this case,
2754 // just add it to the disp field and check validity.
2755 if (VariableOperand == -1) {
2756 AddrMode.BaseOffs += ConstantOffset;
2757 if (ConstantOffset == 0 || TLI.isLegalAddressingMode(AddrMode, AccessTy)){
2758 // Check to see if we can fold the base pointer in too.
2759 if (MatchAddr(AddrInst->getOperand(0), Depth+1))
2762 AddrMode.BaseOffs -= ConstantOffset;
2766 // Save the valid addressing mode in case we can't match.
2767 ExtAddrMode BackupAddrMode = AddrMode;
2768 unsigned OldSize = AddrModeInsts.size();
2770 // See if the scale and offset amount is valid for this target.
2771 AddrMode.BaseOffs += ConstantOffset;
2773 // Match the base operand of the GEP.
2774 if (!MatchAddr(AddrInst->getOperand(0), Depth+1)) {
2775 // If it couldn't be matched, just stuff the value in a register.
2776 if (AddrMode.HasBaseReg) {
2777 AddrMode = BackupAddrMode;
2778 AddrModeInsts.resize(OldSize);
2781 AddrMode.HasBaseReg = true;
2782 AddrMode.BaseReg = AddrInst->getOperand(0);
2785 // Match the remaining variable portion of the GEP.
2786 if (!MatchScaledValue(AddrInst->getOperand(VariableOperand), VariableScale,
2788 // If it couldn't be matched, try stuffing the base into a register
2789 // instead of matching it, and retrying the match of the scale.
2790 AddrMode = BackupAddrMode;
2791 AddrModeInsts.resize(OldSize);
2792 if (AddrMode.HasBaseReg)
2794 AddrMode.HasBaseReg = true;
2795 AddrMode.BaseReg = AddrInst->getOperand(0);
2796 AddrMode.BaseOffs += ConstantOffset;
2797 if (!MatchScaledValue(AddrInst->getOperand(VariableOperand),
2798 VariableScale, Depth)) {
2799 // If even that didn't work, bail.
2800 AddrMode = BackupAddrMode;
2801 AddrModeInsts.resize(OldSize);
2808 case Instruction::SExt:
2809 case Instruction::ZExt: {
2810 Instruction *Ext = dyn_cast<Instruction>(AddrInst);
2814 // Try to move this ext out of the way of the addressing mode.
2815 // Ask for a method for doing so.
2816 TypePromotionHelper::Action TPH =
2817 TypePromotionHelper::getAction(Ext, InsertedTruncs, TLI, PromotedInsts);
2821 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
2822 TPT.getRestorationPoint();
2823 unsigned CreatedInstsCost = 0;
2824 unsigned ExtCost = !TLI.isExtFree(Ext);
2825 Value *PromotedOperand =
2826 TPH(Ext, TPT, PromotedInsts, CreatedInstsCost, nullptr, nullptr, TLI);
2827 // SExt has been moved away.
2828 // Thus either it will be rematched later in the recursive calls or it is
2829 // gone. Anyway, we must not fold it into the addressing mode at this point.
2833 // addr = gep base, idx
2835 // promotedOpnd = ext opnd <- no match here
2836 // op = promoted_add promotedOpnd, 1 <- match (later in recursive calls)
2837 // addr = gep base, op <- match
2841 assert(PromotedOperand &&
2842 "TypePromotionHelper should have filtered out those cases");
2844 ExtAddrMode BackupAddrMode = AddrMode;
2845 unsigned OldSize = AddrModeInsts.size();
2847 if (!MatchAddr(PromotedOperand, Depth) ||
2848 // The total of the new cost is equals to the cost of the created
2850 // The total of the old cost is equals to the cost of the extension plus
2851 // what we have saved in the addressing mode.
2852 !IsPromotionProfitable(CreatedInstsCost,
2853 ExtCost + (AddrModeInsts.size() - OldSize),
2855 AddrMode = BackupAddrMode;
2856 AddrModeInsts.resize(OldSize);
2857 DEBUG(dbgs() << "Sign extension does not pay off: rollback\n");
2858 TPT.rollback(LastKnownGood);
2867 /// MatchAddr - If we can, try to add the value of 'Addr' into the current
2868 /// addressing mode. If Addr can't be added to AddrMode this returns false and
2869 /// leaves AddrMode unmodified. This assumes that Addr is either a pointer type
2870 /// or intptr_t for the target.
2872 bool AddressingModeMatcher::MatchAddr(Value *Addr, unsigned Depth) {
2873 // Start a transaction at this point that we will rollback if the matching
2875 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
2876 TPT.getRestorationPoint();
2877 if (ConstantInt *CI = dyn_cast<ConstantInt>(Addr)) {
2878 // Fold in immediates if legal for the target.
2879 AddrMode.BaseOffs += CI->getSExtValue();
2880 if (TLI.isLegalAddressingMode(AddrMode, AccessTy))
2882 AddrMode.BaseOffs -= CI->getSExtValue();
2883 } else if (GlobalValue *GV = dyn_cast<GlobalValue>(Addr)) {
2884 // If this is a global variable, try to fold it into the addressing mode.
2885 if (!AddrMode.BaseGV) {
2886 AddrMode.BaseGV = GV;
2887 if (TLI.isLegalAddressingMode(AddrMode, AccessTy))
2889 AddrMode.BaseGV = nullptr;
2891 } else if (Instruction *I = dyn_cast<Instruction>(Addr)) {
2892 ExtAddrMode BackupAddrMode = AddrMode;
2893 unsigned OldSize = AddrModeInsts.size();
2895 // Check to see if it is possible to fold this operation.
2896 bool MovedAway = false;
2897 if (MatchOperationAddr(I, I->getOpcode(), Depth, &MovedAway)) {
2898 // This instruction may have been move away. If so, there is nothing
2902 // Okay, it's possible to fold this. Check to see if it is actually
2903 // *profitable* to do so. We use a simple cost model to avoid increasing
2904 // register pressure too much.
2905 if (I->hasOneUse() ||
2906 IsProfitableToFoldIntoAddressingMode(I, BackupAddrMode, AddrMode)) {
2907 AddrModeInsts.push_back(I);
2911 // It isn't profitable to do this, roll back.
2912 //cerr << "NOT FOLDING: " << *I;
2913 AddrMode = BackupAddrMode;
2914 AddrModeInsts.resize(OldSize);
2915 TPT.rollback(LastKnownGood);
2917 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Addr)) {
2918 if (MatchOperationAddr(CE, CE->getOpcode(), Depth))
2920 TPT.rollback(LastKnownGood);
2921 } else if (isa<ConstantPointerNull>(Addr)) {
2922 // Null pointer gets folded without affecting the addressing mode.
2926 // Worse case, the target should support [reg] addressing modes. :)
2927 if (!AddrMode.HasBaseReg) {
2928 AddrMode.HasBaseReg = true;
2929 AddrMode.BaseReg = Addr;
2930 // Still check for legality in case the target supports [imm] but not [i+r].
2931 if (TLI.isLegalAddressingMode(AddrMode, AccessTy))
2933 AddrMode.HasBaseReg = false;
2934 AddrMode.BaseReg = nullptr;
2937 // If the base register is already taken, see if we can do [r+r].
2938 if (AddrMode.Scale == 0) {
2940 AddrMode.ScaledReg = Addr;
2941 if (TLI.isLegalAddressingMode(AddrMode, AccessTy))
2944 AddrMode.ScaledReg = nullptr;
2947 TPT.rollback(LastKnownGood);
2951 /// IsOperandAMemoryOperand - Check to see if all uses of OpVal by the specified
2952 /// inline asm call are due to memory operands. If so, return true, otherwise
2954 static bool IsOperandAMemoryOperand(CallInst *CI, InlineAsm *IA, Value *OpVal,
2955 const TargetMachine &TM) {
2956 const Function *F = CI->getParent()->getParent();
2957 const TargetLowering *TLI = TM.getSubtargetImpl(*F)->getTargetLowering();
2958 const TargetRegisterInfo *TRI = TM.getSubtargetImpl(*F)->getRegisterInfo();
2959 TargetLowering::AsmOperandInfoVector TargetConstraints =
2960 TLI->ParseConstraints(TRI, ImmutableCallSite(CI));
2961 for (unsigned i = 0, e = TargetConstraints.size(); i != e; ++i) {
2962 TargetLowering::AsmOperandInfo &OpInfo = TargetConstraints[i];
2964 // Compute the constraint code and ConstraintType to use.
2965 TLI->ComputeConstraintToUse(OpInfo, SDValue());
2967 // If this asm operand is our Value*, and if it isn't an indirect memory
2968 // operand, we can't fold it!
2969 if (OpInfo.CallOperandVal == OpVal &&
2970 (OpInfo.ConstraintType != TargetLowering::C_Memory ||
2971 !OpInfo.isIndirect))
2978 /// FindAllMemoryUses - Recursively walk all the uses of I until we find a
2979 /// memory use. If we find an obviously non-foldable instruction, return true.
2980 /// Add the ultimately found memory instructions to MemoryUses.
2981 static bool FindAllMemoryUses(
2983 SmallVectorImpl<std::pair<Instruction *, unsigned>> &MemoryUses,
2984 SmallPtrSetImpl<Instruction *> &ConsideredInsts, const TargetMachine &TM) {
2985 // If we already considered this instruction, we're done.
2986 if (!ConsideredInsts.insert(I).second)
2989 // If this is an obviously unfoldable instruction, bail out.
2990 if (!MightBeFoldableInst(I))
2993 // Loop over all the uses, recursively processing them.
2994 for (Use &U : I->uses()) {
2995 Instruction *UserI = cast<Instruction>(U.getUser());
2997 if (LoadInst *LI = dyn_cast<LoadInst>(UserI)) {
2998 MemoryUses.push_back(std::make_pair(LI, U.getOperandNo()));
3002 if (StoreInst *SI = dyn_cast<StoreInst>(UserI)) {
3003 unsigned opNo = U.getOperandNo();
3004 if (opNo == 0) return true; // Storing addr, not into addr.
3005 MemoryUses.push_back(std::make_pair(SI, opNo));
3009 if (CallInst *CI = dyn_cast<CallInst>(UserI)) {
3010 InlineAsm *IA = dyn_cast<InlineAsm>(CI->getCalledValue());
3011 if (!IA) return true;
3013 // If this is a memory operand, we're cool, otherwise bail out.
3014 if (!IsOperandAMemoryOperand(CI, IA, I, TM))
3019 if (FindAllMemoryUses(UserI, MemoryUses, ConsideredInsts, TM))
3026 /// ValueAlreadyLiveAtInst - Retrn true if Val is already known to be live at
3027 /// the use site that we're folding it into. If so, there is no cost to
3028 /// include it in the addressing mode. KnownLive1 and KnownLive2 are two values
3029 /// that we know are live at the instruction already.
3030 bool AddressingModeMatcher::ValueAlreadyLiveAtInst(Value *Val,Value *KnownLive1,
3031 Value *KnownLive2) {
3032 // If Val is either of the known-live values, we know it is live!
3033 if (Val == nullptr || Val == KnownLive1 || Val == KnownLive2)
3036 // All values other than instructions and arguments (e.g. constants) are live.
3037 if (!isa<Instruction>(Val) && !isa<Argument>(Val)) return true;
3039 // If Val is a constant sized alloca in the entry block, it is live, this is
3040 // true because it is just a reference to the stack/frame pointer, which is
3041 // live for the whole function.
3042 if (AllocaInst *AI = dyn_cast<AllocaInst>(Val))
3043 if (AI->isStaticAlloca())
3046 // Check to see if this value is already used in the memory instruction's
3047 // block. If so, it's already live into the block at the very least, so we
3048 // can reasonably fold it.
3049 return Val->isUsedInBasicBlock(MemoryInst->getParent());
3052 /// IsProfitableToFoldIntoAddressingMode - It is possible for the addressing
3053 /// mode of the machine to fold the specified instruction into a load or store
3054 /// that ultimately uses it. However, the specified instruction has multiple
3055 /// uses. Given this, it may actually increase register pressure to fold it
3056 /// into the load. For example, consider this code:
3060 /// use(Y) -> nonload/store
3064 /// In this case, Y has multiple uses, and can be folded into the load of Z
3065 /// (yielding load [X+2]). However, doing this will cause both "X" and "X+1" to
3066 /// be live at the use(Y) line. If we don't fold Y into load Z, we use one
3067 /// fewer register. Since Y can't be folded into "use(Y)" we don't increase the
3068 /// number of computations either.
3070 /// Note that this (like most of CodeGenPrepare) is just a rough heuristic. If
3071 /// X was live across 'load Z' for other reasons, we actually *would* want to
3072 /// fold the addressing mode in the Z case. This would make Y die earlier.
3073 bool AddressingModeMatcher::
3074 IsProfitableToFoldIntoAddressingMode(Instruction *I, ExtAddrMode &AMBefore,
3075 ExtAddrMode &AMAfter) {
3076 if (IgnoreProfitability) return true;
3078 // AMBefore is the addressing mode before this instruction was folded into it,
3079 // and AMAfter is the addressing mode after the instruction was folded. Get
3080 // the set of registers referenced by AMAfter and subtract out those
3081 // referenced by AMBefore: this is the set of values which folding in this
3082 // address extends the lifetime of.
3084 // Note that there are only two potential values being referenced here,
3085 // BaseReg and ScaleReg (global addresses are always available, as are any
3086 // folded immediates).
3087 Value *BaseReg = AMAfter.BaseReg, *ScaledReg = AMAfter.ScaledReg;
3089 // If the BaseReg or ScaledReg was referenced by the previous addrmode, their
3090 // lifetime wasn't extended by adding this instruction.
3091 if (ValueAlreadyLiveAtInst(BaseReg, AMBefore.BaseReg, AMBefore.ScaledReg))
3093 if (ValueAlreadyLiveAtInst(ScaledReg, AMBefore.BaseReg, AMBefore.ScaledReg))
3094 ScaledReg = nullptr;
3096 // If folding this instruction (and it's subexprs) didn't extend any live
3097 // ranges, we're ok with it.
3098 if (!BaseReg && !ScaledReg)
3101 // If all uses of this instruction are ultimately load/store/inlineasm's,
3102 // check to see if their addressing modes will include this instruction. If
3103 // so, we can fold it into all uses, so it doesn't matter if it has multiple
3105 SmallVector<std::pair<Instruction*,unsigned>, 16> MemoryUses;
3106 SmallPtrSet<Instruction*, 16> ConsideredInsts;
3107 if (FindAllMemoryUses(I, MemoryUses, ConsideredInsts, TM))
3108 return false; // Has a non-memory, non-foldable use!
3110 // Now that we know that all uses of this instruction are part of a chain of
3111 // computation involving only operations that could theoretically be folded
3112 // into a memory use, loop over each of these uses and see if they could
3113 // *actually* fold the instruction.
3114 SmallVector<Instruction*, 32> MatchedAddrModeInsts;
3115 for (unsigned i = 0, e = MemoryUses.size(); i != e; ++i) {
3116 Instruction *User = MemoryUses[i].first;
3117 unsigned OpNo = MemoryUses[i].second;
3119 // Get the access type of this use. If the use isn't a pointer, we don't
3120 // know what it accesses.
3121 Value *Address = User->getOperand(OpNo);
3122 if (!Address->getType()->isPointerTy())
3124 Type *AddressAccessTy = Address->getType()->getPointerElementType();
3126 // Do a match against the root of this address, ignoring profitability. This
3127 // will tell us if the addressing mode for the memory operation will
3128 // *actually* cover the shared instruction.
3130 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
3131 TPT.getRestorationPoint();
3132 AddressingModeMatcher Matcher(MatchedAddrModeInsts, TM, AddressAccessTy,
3133 MemoryInst, Result, InsertedTruncs,
3134 PromotedInsts, TPT);
3135 Matcher.IgnoreProfitability = true;
3136 bool Success = Matcher.MatchAddr(Address, 0);
3137 (void)Success; assert(Success && "Couldn't select *anything*?");
3139 // The match was to check the profitability, the changes made are not
3140 // part of the original matcher. Therefore, they should be dropped
3141 // otherwise the original matcher will not present the right state.
3142 TPT.rollback(LastKnownGood);
3144 // If the match didn't cover I, then it won't be shared by it.
3145 if (std::find(MatchedAddrModeInsts.begin(), MatchedAddrModeInsts.end(),
3146 I) == MatchedAddrModeInsts.end())
3149 MatchedAddrModeInsts.clear();
3155 } // end anonymous namespace
3157 /// IsNonLocalValue - Return true if the specified values are defined in a
3158 /// different basic block than BB.
3159 static bool IsNonLocalValue(Value *V, BasicBlock *BB) {
3160 if (Instruction *I = dyn_cast<Instruction>(V))
3161 return I->getParent() != BB;
3165 /// OptimizeMemoryInst - Load and Store Instructions often have
3166 /// addressing modes that can do significant amounts of computation. As such,
3167 /// instruction selection will try to get the load or store to do as much
3168 /// computation as possible for the program. The problem is that isel can only
3169 /// see within a single block. As such, we sink as much legal addressing mode
3170 /// stuff into the block as possible.
3172 /// This method is used to optimize both load/store and inline asms with memory
3174 bool CodeGenPrepare::OptimizeMemoryInst(Instruction *MemoryInst, Value *Addr,
3178 // Try to collapse single-value PHI nodes. This is necessary to undo
3179 // unprofitable PRE transformations.
3180 SmallVector<Value*, 8> worklist;
3181 SmallPtrSet<Value*, 16> Visited;
3182 worklist.push_back(Addr);
3184 // Use a worklist to iteratively look through PHI nodes, and ensure that
3185 // the addressing mode obtained from the non-PHI roots of the graph
3187 Value *Consensus = nullptr;
3188 unsigned NumUsesConsensus = 0;
3189 bool IsNumUsesConsensusValid = false;
3190 SmallVector<Instruction*, 16> AddrModeInsts;
3191 ExtAddrMode AddrMode;
3192 TypePromotionTransaction TPT;
3193 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
3194 TPT.getRestorationPoint();
3195 while (!worklist.empty()) {
3196 Value *V = worklist.back();
3197 worklist.pop_back();
3199 // Break use-def graph loops.
3200 if (!Visited.insert(V).second) {
3201 Consensus = nullptr;
3205 // For a PHI node, push all of its incoming values.
3206 if (PHINode *P = dyn_cast<PHINode>(V)) {
3207 for (Value *IncValue : P->incoming_values())
3208 worklist.push_back(IncValue);
3212 // For non-PHIs, determine the addressing mode being computed.
3213 SmallVector<Instruction*, 16> NewAddrModeInsts;
3214 ExtAddrMode NewAddrMode = AddressingModeMatcher::Match(
3215 V, AccessTy, MemoryInst, NewAddrModeInsts, *TM, InsertedTruncsSet,
3216 PromotedInsts, TPT);
3218 // This check is broken into two cases with very similar code to avoid using
3219 // getNumUses() as much as possible. Some values have a lot of uses, so
3220 // calling getNumUses() unconditionally caused a significant compile-time
3224 AddrMode = NewAddrMode;
3225 AddrModeInsts = NewAddrModeInsts;
3227 } else if (NewAddrMode == AddrMode) {
3228 if (!IsNumUsesConsensusValid) {
3229 NumUsesConsensus = Consensus->getNumUses();
3230 IsNumUsesConsensusValid = true;
3233 // Ensure that the obtained addressing mode is equivalent to that obtained
3234 // for all other roots of the PHI traversal. Also, when choosing one
3235 // such root as representative, select the one with the most uses in order
3236 // to keep the cost modeling heuristics in AddressingModeMatcher
3238 unsigned NumUses = V->getNumUses();
3239 if (NumUses > NumUsesConsensus) {
3241 NumUsesConsensus = NumUses;
3242 AddrModeInsts = NewAddrModeInsts;
3247 Consensus = nullptr;
3251 // If the addressing mode couldn't be determined, or if multiple different
3252 // ones were determined, bail out now.
3254 TPT.rollback(LastKnownGood);
3259 // Check to see if any of the instructions supersumed by this addr mode are
3260 // non-local to I's BB.
3261 bool AnyNonLocal = false;
3262 for (unsigned i = 0, e = AddrModeInsts.size(); i != e; ++i) {
3263 if (IsNonLocalValue(AddrModeInsts[i], MemoryInst->getParent())) {
3269 // If all the instructions matched are already in this BB, don't do anything.
3271 DEBUG(dbgs() << "CGP: Found local addrmode: " << AddrMode << "\n");
3275 // Insert this computation right after this user. Since our caller is
3276 // scanning from the top of the BB to the bottom, reuse of the expr are
3277 // guaranteed to happen later.
3278 IRBuilder<> Builder(MemoryInst);
3280 // Now that we determined the addressing expression we want to use and know
3281 // that we have to sink it into this block. Check to see if we have already
3282 // done this for some other load/store instr in this block. If so, reuse the
3284 Value *&SunkAddr = SunkAddrs[Addr];
3286 DEBUG(dbgs() << "CGP: Reusing nonlocal addrmode: " << AddrMode << " for "
3287 << *MemoryInst << "\n");
3288 if (SunkAddr->getType() != Addr->getType())
3289 SunkAddr = Builder.CreateBitCast(SunkAddr, Addr->getType());
3290 } else if (AddrSinkUsingGEPs ||
3291 (!AddrSinkUsingGEPs.getNumOccurrences() && TM &&
3292 TM->getSubtargetImpl(*MemoryInst->getParent()->getParent())
3294 // By default, we use the GEP-based method when AA is used later. This
3295 // prevents new inttoptr/ptrtoint pairs from degrading AA capabilities.
3296 DEBUG(dbgs() << "CGP: SINKING nonlocal addrmode: " << AddrMode << " for "
3297 << *MemoryInst << "\n");
3298 Type *IntPtrTy = TLI->getDataLayout()->getIntPtrType(Addr->getType());
3299 Value *ResultPtr = nullptr, *ResultIndex = nullptr;
3301 // First, find the pointer.
3302 if (AddrMode.BaseReg && AddrMode.BaseReg->getType()->isPointerTy()) {
3303 ResultPtr = AddrMode.BaseReg;
3304 AddrMode.BaseReg = nullptr;
3307 if (AddrMode.Scale && AddrMode.ScaledReg->getType()->isPointerTy()) {
3308 // We can't add more than one pointer together, nor can we scale a
3309 // pointer (both of which seem meaningless).
3310 if (ResultPtr || AddrMode.Scale != 1)
3313 ResultPtr = AddrMode.ScaledReg;
3317 if (AddrMode.BaseGV) {
3321 ResultPtr = AddrMode.BaseGV;
3324 // If the real base value actually came from an inttoptr, then the matcher
3325 // will look through it and provide only the integer value. In that case,
3327 if (!ResultPtr && AddrMode.BaseReg) {
3329 Builder.CreateIntToPtr(AddrMode.BaseReg, Addr->getType(), "sunkaddr");
3330 AddrMode.BaseReg = nullptr;
3331 } else if (!ResultPtr && AddrMode.Scale == 1) {
3333 Builder.CreateIntToPtr(AddrMode.ScaledReg, Addr->getType(), "sunkaddr");
3338 !AddrMode.BaseReg && !AddrMode.Scale && !AddrMode.BaseOffs) {
3339 SunkAddr = Constant::getNullValue(Addr->getType());
3340 } else if (!ResultPtr) {
3344 Builder.getInt8PtrTy(Addr->getType()->getPointerAddressSpace());
3345 Type *I8Ty = Builder.getInt8Ty();
3347 // Start with the base register. Do this first so that subsequent address
3348 // matching finds it last, which will prevent it from trying to match it
3349 // as the scaled value in case it happens to be a mul. That would be
3350 // problematic if we've sunk a different mul for the scale, because then
3351 // we'd end up sinking both muls.
3352 if (AddrMode.BaseReg) {
3353 Value *V = AddrMode.BaseReg;
3354 if (V->getType() != IntPtrTy)
3355 V = Builder.CreateIntCast(V, IntPtrTy, /*isSigned=*/true, "sunkaddr");
3360 // Add the scale value.
3361 if (AddrMode.Scale) {
3362 Value *V = AddrMode.ScaledReg;
3363 if (V->getType() == IntPtrTy) {
3365 } else if (cast<IntegerType>(IntPtrTy)->getBitWidth() <
3366 cast<IntegerType>(V->getType())->getBitWidth()) {
3367 V = Builder.CreateTrunc(V, IntPtrTy, "sunkaddr");
3369 // It is only safe to sign extend the BaseReg if we know that the math
3370 // required to create it did not overflow before we extend it. Since
3371 // the original IR value was tossed in favor of a constant back when
3372 // the AddrMode was created we need to bail out gracefully if widths
3373 // do not match instead of extending it.
3374 Instruction *I = dyn_cast_or_null<Instruction>(ResultIndex);
3375 if (I && (ResultIndex != AddrMode.BaseReg))
3376 I->eraseFromParent();
3380 if (AddrMode.Scale != 1)
3381 V = Builder.CreateMul(V, ConstantInt::get(IntPtrTy, AddrMode.Scale),
3384 ResultIndex = Builder.CreateAdd(ResultIndex, V, "sunkaddr");
3389 // Add in the Base Offset if present.
3390 if (AddrMode.BaseOffs) {
3391 Value *V = ConstantInt::get(IntPtrTy, AddrMode.BaseOffs);
3393 // We need to add this separately from the scale above to help with
3394 // SDAG consecutive load/store merging.
3395 if (ResultPtr->getType() != I8PtrTy)
3396 ResultPtr = Builder.CreateBitCast(ResultPtr, I8PtrTy);
3397 ResultPtr = Builder.CreateGEP(I8Ty, ResultPtr, ResultIndex, "sunkaddr");
3404 SunkAddr = ResultPtr;
3406 if (ResultPtr->getType() != I8PtrTy)
3407 ResultPtr = Builder.CreateBitCast(ResultPtr, I8PtrTy);
3408 SunkAddr = Builder.CreateGEP(I8Ty, ResultPtr, ResultIndex, "sunkaddr");
3411 if (SunkAddr->getType() != Addr->getType())
3412 SunkAddr = Builder.CreateBitCast(SunkAddr, Addr->getType());
3415 DEBUG(dbgs() << "CGP: SINKING nonlocal addrmode: " << AddrMode << " for "
3416 << *MemoryInst << "\n");
3417 Type *IntPtrTy = TLI->getDataLayout()->getIntPtrType(Addr->getType());
3418 Value *Result = nullptr;
3420 // Start with the base register. Do this first so that subsequent address
3421 // matching finds it last, which will prevent it from trying to match it
3422 // as the scaled value in case it happens to be a mul. That would be
3423 // problematic if we've sunk a different mul for the scale, because then
3424 // we'd end up sinking both muls.
3425 if (AddrMode.BaseReg) {
3426 Value *V = AddrMode.BaseReg;
3427 if (V->getType()->isPointerTy())
3428 V = Builder.CreatePtrToInt(V, IntPtrTy, "sunkaddr");
3429 if (V->getType() != IntPtrTy)
3430 V = Builder.CreateIntCast(V, IntPtrTy, /*isSigned=*/true, "sunkaddr");
3434 // Add the scale value.
3435 if (AddrMode.Scale) {
3436 Value *V = AddrMode.ScaledReg;
3437 if (V->getType() == IntPtrTy) {
3439 } else if (V->getType()->isPointerTy()) {
3440 V = Builder.CreatePtrToInt(V, IntPtrTy, "sunkaddr");
3441 } else if (cast<IntegerType>(IntPtrTy)->getBitWidth() <
3442 cast<IntegerType>(V->getType())->getBitWidth()) {
3443 V = Builder.CreateTrunc(V, IntPtrTy, "sunkaddr");
3445 // It is only safe to sign extend the BaseReg if we know that the math
3446 // required to create it did not overflow before we extend it. Since
3447 // the original IR value was tossed in favor of a constant back when
3448 // the AddrMode was created we need to bail out gracefully if widths
3449 // do not match instead of extending it.
3450 Instruction *I = dyn_cast_or_null<Instruction>(Result);
3451 if (I && (Result != AddrMode.BaseReg))
3452 I->eraseFromParent();
3455 if (AddrMode.Scale != 1)
3456 V = Builder.CreateMul(V, ConstantInt::get(IntPtrTy, AddrMode.Scale),
3459 Result = Builder.CreateAdd(Result, V, "sunkaddr");
3464 // Add in the BaseGV if present.
3465 if (AddrMode.BaseGV) {
3466 Value *V = Builder.CreatePtrToInt(AddrMode.BaseGV, IntPtrTy, "sunkaddr");
3468 Result = Builder.CreateAdd(Result, V, "sunkaddr");
3473 // Add in the Base Offset if present.
3474 if (AddrMode.BaseOffs) {
3475 Value *V = ConstantInt::get(IntPtrTy, AddrMode.BaseOffs);
3477 Result = Builder.CreateAdd(Result, V, "sunkaddr");
3483 SunkAddr = Constant::getNullValue(Addr->getType());
3485 SunkAddr = Builder.CreateIntToPtr(Result, Addr->getType(), "sunkaddr");
3488 MemoryInst->replaceUsesOfWith(Repl, SunkAddr);
3490 // If we have no uses, recursively delete the value and all dead instructions
3492 if (Repl->use_empty()) {
3493 // This can cause recursive deletion, which can invalidate our iterator.
3494 // Use a WeakVH to hold onto it in case this happens.
3495 WeakVH IterHandle(CurInstIterator);
3496 BasicBlock *BB = CurInstIterator->getParent();
3498 RecursivelyDeleteTriviallyDeadInstructions(Repl, TLInfo);
3500 if (IterHandle != CurInstIterator) {
3501 // If the iterator instruction was recursively deleted, start over at the
3502 // start of the block.
3503 CurInstIterator = BB->begin();
3511 /// OptimizeInlineAsmInst - If there are any memory operands, use
3512 /// OptimizeMemoryInst to sink their address computing into the block when
3513 /// possible / profitable.
3514 bool CodeGenPrepare::OptimizeInlineAsmInst(CallInst *CS) {
3515 bool MadeChange = false;
3517 const TargetRegisterInfo *TRI =
3518 TM->getSubtargetImpl(*CS->getParent()->getParent())->getRegisterInfo();
3519 TargetLowering::AsmOperandInfoVector
3520 TargetConstraints = TLI->ParseConstraints(TRI, CS);
3522 for (unsigned i = 0, e = TargetConstraints.size(); i != e; ++i) {
3523 TargetLowering::AsmOperandInfo &OpInfo = TargetConstraints[i];
3525 // Compute the constraint code and ConstraintType to use.
3526 TLI->ComputeConstraintToUse(OpInfo, SDValue());
3528 if (OpInfo.ConstraintType == TargetLowering::C_Memory &&
3529 OpInfo.isIndirect) {
3530 Value *OpVal = CS->getArgOperand(ArgNo++);
3531 MadeChange |= OptimizeMemoryInst(CS, OpVal, OpVal->getType());
3532 } else if (OpInfo.Type == InlineAsm::isInput)
3539 /// \brief Check if all the uses of \p Inst are equivalent (or free) zero or
3540 /// sign extensions.
3541 static bool hasSameExtUse(Instruction *Inst, const TargetLowering &TLI) {
3542 assert(!Inst->use_empty() && "Input must have at least one use");
3543 const Instruction *FirstUser = cast<Instruction>(*Inst->user_begin());
3544 bool IsSExt = isa<SExtInst>(FirstUser);
3545 Type *ExtTy = FirstUser->getType();
3546 for (const User *U : Inst->users()) {
3547 const Instruction *UI = cast<Instruction>(U);
3548 if ((IsSExt && !isa<SExtInst>(UI)) || (!IsSExt && !isa<ZExtInst>(UI)))
3550 Type *CurTy = UI->getType();
3551 // Same input and output types: Same instruction after CSE.
3555 // If IsSExt is true, we are in this situation:
3557 // b = sext ty1 a to ty2
3558 // c = sext ty1 a to ty3
3559 // Assuming ty2 is shorter than ty3, this could be turned into:
3561 // b = sext ty1 a to ty2
3562 // c = sext ty2 b to ty3
3563 // However, the last sext is not free.
3567 // This is a ZExt, maybe this is free to extend from one type to another.
3568 // In that case, we would not account for a different use.
3571 if (ExtTy->getScalarType()->getIntegerBitWidth() >
3572 CurTy->getScalarType()->getIntegerBitWidth()) {
3580 if (!TLI.isZExtFree(NarrowTy, LargeTy))
3583 // All uses are the same or can be derived from one another for free.
3587 /// \brief Try to form ExtLd by promoting \p Exts until they reach a
3588 /// load instruction.
3589 /// If an ext(load) can be formed, it is returned via \p LI for the load
3590 /// and \p Inst for the extension.
3591 /// Otherwise LI == nullptr and Inst == nullptr.
3592 /// When some promotion happened, \p TPT contains the proper state to
3595 /// \return true when promoting was necessary to expose the ext(load)
3596 /// opportunity, false otherwise.
3600 /// %ld = load i32* %addr
3601 /// %add = add nuw i32 %ld, 4
3602 /// %zext = zext i32 %add to i64
3606 /// %ld = load i32* %addr
3607 /// %zext = zext i32 %ld to i64
3608 /// %add = add nuw i64 %zext, 4
3610 /// Thanks to the promotion, we can match zext(load i32*) to i64.
3611 bool CodeGenPrepare::ExtLdPromotion(TypePromotionTransaction &TPT,
3612 LoadInst *&LI, Instruction *&Inst,
3613 const SmallVectorImpl<Instruction *> &Exts,
3614 unsigned CreatedInstsCost = 0) {
3615 // Iterate over all the extensions to see if one form an ext(load).
3616 for (auto I : Exts) {
3617 // Check if we directly have ext(load).
3618 if ((LI = dyn_cast<LoadInst>(I->getOperand(0)))) {
3620 // No promotion happened here.
3623 // Check whether or not we want to do any promotion.
3624 if (!TLI || !TLI->enableExtLdPromotion() || DisableExtLdPromotion)
3626 // Get the action to perform the promotion.
3627 TypePromotionHelper::Action TPH = TypePromotionHelper::getAction(
3628 I, InsertedTruncsSet, *TLI, PromotedInsts);
3629 // Check if we can promote.
3632 // Save the current state.
3633 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
3634 TPT.getRestorationPoint();
3635 SmallVector<Instruction *, 4> NewExts;
3636 unsigned NewCreatedInstsCost = 0;
3637 unsigned ExtCost = !TLI->isExtFree(I);
3639 Value *PromotedVal = TPH(I, TPT, PromotedInsts, NewCreatedInstsCost,
3640 &NewExts, nullptr, *TLI);
3641 assert(PromotedVal &&
3642 "TypePromotionHelper should have filtered out those cases");
3644 // We would be able to merge only one extension in a load.
3645 // Therefore, if we have more than 1 new extension we heuristically
3646 // cut this search path, because it means we degrade the code quality.
3647 // With exactly 2, the transformation is neutral, because we will merge
3648 // one extension but leave one. However, we optimistically keep going,
3649 // because the new extension may be removed too.
3650 long long TotalCreatedInstsCost = CreatedInstsCost + NewCreatedInstsCost;
3651 TotalCreatedInstsCost -= ExtCost;
3652 if (!StressExtLdPromotion &&
3653 (TotalCreatedInstsCost > 1 ||
3654 !isPromotedInstructionLegal(*TLI, PromotedVal))) {
3655 // The promotion is not profitable, rollback to the previous state.
3656 TPT.rollback(LastKnownGood);
3659 // The promotion is profitable.
3660 // Check if it exposes an ext(load).
3661 (void)ExtLdPromotion(TPT, LI, Inst, NewExts, TotalCreatedInstsCost);
3662 if (LI && (StressExtLdPromotion || NewCreatedInstsCost <= ExtCost ||
3663 // If we have created a new extension, i.e., now we have two
3664 // extensions. We must make sure one of them is merged with
3665 // the load, otherwise we may degrade the code quality.
3666 (LI->hasOneUse() || hasSameExtUse(LI, *TLI))))
3667 // Promotion happened.
3669 // If this does not help to expose an ext(load) then, rollback.
3670 TPT.rollback(LastKnownGood);
3672 // None of the extension can form an ext(load).
3678 /// MoveExtToFormExtLoad - Move a zext or sext fed by a load into the same
3679 /// basic block as the load, unless conditions are unfavorable. This allows
3680 /// SelectionDAG to fold the extend into the load.
3681 /// \p I[in/out] the extension may be modified during the process if some
3682 /// promotions apply.
3684 bool CodeGenPrepare::MoveExtToFormExtLoad(Instruction *&I) {
3685 // Try to promote a chain of computation if it allows to form
3686 // an extended load.
3687 TypePromotionTransaction TPT;
3688 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
3689 TPT.getRestorationPoint();
3690 SmallVector<Instruction *, 1> Exts;
3692 // Look for a load being extended.
3693 LoadInst *LI = nullptr;
3694 Instruction *OldExt = I;
3695 bool HasPromoted = ExtLdPromotion(TPT, LI, I, Exts);
3697 assert(!HasPromoted && !LI && "If we did not match any load instruction "
3698 "the code must remain the same");
3703 // If they're already in the same block, there's nothing to do.
3704 // Make the cheap checks first if we did not promote.
3705 // If we promoted, we need to check if it is indeed profitable.
3706 if (!HasPromoted && LI->getParent() == I->getParent())
3709 EVT VT = TLI->getValueType(I->getType());
3710 EVT LoadVT = TLI->getValueType(LI->getType());
3712 // If the load has other users and the truncate is not free, this probably
3713 // isn't worthwhile.
3714 if (!LI->hasOneUse() && TLI &&
3715 (TLI->isTypeLegal(LoadVT) || !TLI->isTypeLegal(VT)) &&
3716 !TLI->isTruncateFree(I->getType(), LI->getType())) {
3718 TPT.rollback(LastKnownGood);
3722 // Check whether the target supports casts folded into loads.
3724 if (isa<ZExtInst>(I))
3725 LType = ISD::ZEXTLOAD;
3727 assert(isa<SExtInst>(I) && "Unexpected ext type!");
3728 LType = ISD::SEXTLOAD;
3730 if (TLI && !TLI->isLoadExtLegal(LType, VT, LoadVT)) {
3732 TPT.rollback(LastKnownGood);
3736 // Move the extend into the same block as the load, so that SelectionDAG
3739 I->removeFromParent();
3745 bool CodeGenPrepare::OptimizeExtUses(Instruction *I) {
3746 BasicBlock *DefBB = I->getParent();
3748 // If the result of a {s|z}ext and its source are both live out, rewrite all
3749 // other uses of the source with result of extension.
3750 Value *Src = I->getOperand(0);
3751 if (Src->hasOneUse())
3754 // Only do this xform if truncating is free.
3755 if (TLI && !TLI->isTruncateFree(I->getType(), Src->getType()))
3758 // Only safe to perform the optimization if the source is also defined in
3760 if (!isa<Instruction>(Src) || DefBB != cast<Instruction>(Src)->getParent())
3763 bool DefIsLiveOut = false;
3764 for (User *U : I->users()) {
3765 Instruction *UI = cast<Instruction>(U);
3767 // Figure out which BB this ext is used in.
3768 BasicBlock *UserBB = UI->getParent();
3769 if (UserBB == DefBB) continue;
3770 DefIsLiveOut = true;
3776 // Make sure none of the uses are PHI nodes.
3777 for (User *U : Src->users()) {
3778 Instruction *UI = cast<Instruction>(U);
3779 BasicBlock *UserBB = UI->getParent();
3780 if (UserBB == DefBB) continue;
3781 // Be conservative. We don't want this xform to end up introducing
3782 // reloads just before load / store instructions.
3783 if (isa<PHINode>(UI) || isa<LoadInst>(UI) || isa<StoreInst>(UI))
3787 // InsertedTruncs - Only insert one trunc in each block once.
3788 DenseMap<BasicBlock*, Instruction*> InsertedTruncs;
3790 bool MadeChange = false;
3791 for (Use &U : Src->uses()) {
3792 Instruction *User = cast<Instruction>(U.getUser());
3794 // Figure out which BB this ext is used in.
3795 BasicBlock *UserBB = User->getParent();
3796 if (UserBB == DefBB) continue;
3798 // Both src and def are live in this block. Rewrite the use.
3799 Instruction *&InsertedTrunc = InsertedTruncs[UserBB];
3801 if (!InsertedTrunc) {
3802 BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
3803 InsertedTrunc = new TruncInst(I, Src->getType(), "", InsertPt);
3804 InsertedTruncsSet.insert(InsertedTrunc);
3807 // Replace a use of the {s|z}ext source with a use of the result.
3816 /// isFormingBranchFromSelectProfitable - Returns true if a SelectInst should be
3817 /// turned into an explicit branch.
3818 static bool isFormingBranchFromSelectProfitable(SelectInst *SI) {
3819 // FIXME: This should use the same heuristics as IfConversion to determine
3820 // whether a select is better represented as a branch. This requires that
3821 // branch probability metadata is preserved for the select, which is not the
3824 CmpInst *Cmp = dyn_cast<CmpInst>(SI->getCondition());
3826 // If the branch is predicted right, an out of order CPU can avoid blocking on
3827 // the compare. Emit cmovs on compares with a memory operand as branches to
3828 // avoid stalls on the load from memory. If the compare has more than one use
3829 // there's probably another cmov or setcc around so it's not worth emitting a
3834 Value *CmpOp0 = Cmp->getOperand(0);
3835 Value *CmpOp1 = Cmp->getOperand(1);
3837 // We check that the memory operand has one use to avoid uses of the loaded
3838 // value directly after the compare, making branches unprofitable.
3839 return Cmp->hasOneUse() &&
3840 ((isa<LoadInst>(CmpOp0) && CmpOp0->hasOneUse()) ||
3841 (isa<LoadInst>(CmpOp1) && CmpOp1->hasOneUse()));
3845 /// If we have a SelectInst that will likely profit from branch prediction,
3846 /// turn it into a branch.
3847 bool CodeGenPrepare::OptimizeSelectInst(SelectInst *SI) {
3848 bool VectorCond = !SI->getCondition()->getType()->isIntegerTy(1);
3850 // Can we convert the 'select' to CF ?
3851 if (DisableSelectToBranch || OptSize || !TLI || VectorCond)
3854 TargetLowering::SelectSupportKind SelectKind;
3856 SelectKind = TargetLowering::VectorMaskSelect;
3857 else if (SI->getType()->isVectorTy())
3858 SelectKind = TargetLowering::ScalarCondVectorVal;
3860 SelectKind = TargetLowering::ScalarValSelect;
3862 // Do we have efficient codegen support for this kind of 'selects' ?
3863 if (TLI->isSelectSupported(SelectKind)) {
3864 // We have efficient codegen support for the select instruction.
3865 // Check if it is profitable to keep this 'select'.
3866 if (!TLI->isPredictableSelectExpensive() ||
3867 !isFormingBranchFromSelectProfitable(SI))
3873 // First, we split the block containing the select into 2 blocks.
3874 BasicBlock *StartBlock = SI->getParent();
3875 BasicBlock::iterator SplitPt = ++(BasicBlock::iterator(SI));
3876 BasicBlock *NextBlock = StartBlock->splitBasicBlock(SplitPt, "select.end");
3878 // Create a new block serving as the landing pad for the branch.
3879 BasicBlock *SmallBlock = BasicBlock::Create(SI->getContext(), "select.mid",
3880 NextBlock->getParent(), NextBlock);
3882 // Move the unconditional branch from the block with the select in it into our
3883 // landing pad block.
3884 StartBlock->getTerminator()->eraseFromParent();
3885 BranchInst::Create(NextBlock, SmallBlock);
3887 // Insert the real conditional branch based on the original condition.
3888 BranchInst::Create(NextBlock, SmallBlock, SI->getCondition(), SI);
3890 // The select itself is replaced with a PHI Node.
3891 PHINode *PN = PHINode::Create(SI->getType(), 2, "", NextBlock->begin());
3893 PN->addIncoming(SI->getTrueValue(), StartBlock);
3894 PN->addIncoming(SI->getFalseValue(), SmallBlock);
3895 SI->replaceAllUsesWith(PN);
3896 SI->eraseFromParent();
3898 // Instruct OptimizeBlock to skip to the next block.
3899 CurInstIterator = StartBlock->end();
3900 ++NumSelectsExpanded;
3904 static bool isBroadcastShuffle(ShuffleVectorInst *SVI) {
3905 SmallVector<int, 16> Mask(SVI->getShuffleMask());
3907 for (unsigned i = 0; i < Mask.size(); ++i) {
3908 if (SplatElem != -1 && Mask[i] != -1 && Mask[i] != SplatElem)
3910 SplatElem = Mask[i];
3916 /// Some targets have expensive vector shifts if the lanes aren't all the same
3917 /// (e.g. x86 only introduced "vpsllvd" and friends with AVX2). In these cases
3918 /// it's often worth sinking a shufflevector splat down to its use so that
3919 /// codegen can spot all lanes are identical.
3920 bool CodeGenPrepare::OptimizeShuffleVectorInst(ShuffleVectorInst *SVI) {
3921 BasicBlock *DefBB = SVI->getParent();
3923 // Only do this xform if variable vector shifts are particularly expensive.
3924 if (!TLI || !TLI->isVectorShiftByScalarCheap(SVI->getType()))
3927 // We only expect better codegen by sinking a shuffle if we can recognise a
3929 if (!isBroadcastShuffle(SVI))
3932 // InsertedShuffles - Only insert a shuffle in each block once.
3933 DenseMap<BasicBlock*, Instruction*> InsertedShuffles;
3935 bool MadeChange = false;
3936 for (User *U : SVI->users()) {
3937 Instruction *UI = cast<Instruction>(U);
3939 // Figure out which BB this ext is used in.
3940 BasicBlock *UserBB = UI->getParent();
3941 if (UserBB == DefBB) continue;
3943 // For now only apply this when the splat is used by a shift instruction.
3944 if (!UI->isShift()) continue;
3946 // Everything checks out, sink the shuffle if the user's block doesn't
3947 // already have a copy.
3948 Instruction *&InsertedShuffle = InsertedShuffles[UserBB];
3950 if (!InsertedShuffle) {
3951 BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
3952 InsertedShuffle = new ShuffleVectorInst(SVI->getOperand(0),
3954 SVI->getOperand(2), "", InsertPt);
3957 UI->replaceUsesOfWith(SVI, InsertedShuffle);
3961 // If we removed all uses, nuke the shuffle.
3962 if (SVI->use_empty()) {
3963 SVI->eraseFromParent();
3971 /// \brief Helper class to promote a scalar operation to a vector one.
3972 /// This class is used to move downward extractelement transition.
3974 /// a = vector_op <2 x i32>
3975 /// b = extractelement <2 x i32> a, i32 0
3980 /// a = vector_op <2 x i32>
3981 /// c = vector_op a (equivalent to scalar_op on the related lane)
3982 /// * d = extractelement <2 x i32> c, i32 0
3984 /// Assuming both extractelement and store can be combine, we get rid of the
3986 class VectorPromoteHelper {
3987 /// Used to perform some checks on the legality of vector operations.
3988 const TargetLowering &TLI;
3990 /// Used to estimated the cost of the promoted chain.
3991 const TargetTransformInfo &TTI;
3993 /// The transition being moved downwards.
3994 Instruction *Transition;
3995 /// The sequence of instructions to be promoted.
3996 SmallVector<Instruction *, 4> InstsToBePromoted;
3997 /// Cost of combining a store and an extract.
3998 unsigned StoreExtractCombineCost;
3999 /// Instruction that will be combined with the transition.
4000 Instruction *CombineInst;
4002 /// \brief The instruction that represents the current end of the transition.
4003 /// Since we are faking the promotion until we reach the end of the chain
4004 /// of computation, we need a way to get the current end of the transition.
4005 Instruction *getEndOfTransition() const {
4006 if (InstsToBePromoted.empty())
4008 return InstsToBePromoted.back();
4011 /// \brief Return the index of the original value in the transition.
4012 /// E.g., for "extractelement <2 x i32> c, i32 1" the original value,
4013 /// c, is at index 0.
4014 unsigned getTransitionOriginalValueIdx() const {
4015 assert(isa<ExtractElementInst>(Transition) &&
4016 "Other kind of transitions are not supported yet");
4020 /// \brief Return the index of the index in the transition.
4021 /// E.g., for "extractelement <2 x i32> c, i32 0" the index
4023 unsigned getTransitionIdx() const {
4024 assert(isa<ExtractElementInst>(Transition) &&
4025 "Other kind of transitions are not supported yet");
4029 /// \brief Get the type of the transition.
4030 /// This is the type of the original value.
4031 /// E.g., for "extractelement <2 x i32> c, i32 1" the type of the
4032 /// transition is <2 x i32>.
4033 Type *getTransitionType() const {
4034 return Transition->getOperand(getTransitionOriginalValueIdx())->getType();
4037 /// \brief Promote \p ToBePromoted by moving \p Def downward through.
4038 /// I.e., we have the following sequence:
4039 /// Def = Transition <ty1> a to <ty2>
4040 /// b = ToBePromoted <ty2> Def, ...
4042 /// b = ToBePromoted <ty1> a, ...
4043 /// Def = Transition <ty1> ToBePromoted to <ty2>
4044 void promoteImpl(Instruction *ToBePromoted);
4046 /// \brief Check whether or not it is profitable to promote all the
4047 /// instructions enqueued to be promoted.
4048 bool isProfitableToPromote() {
4049 Value *ValIdx = Transition->getOperand(getTransitionOriginalValueIdx());
4050 unsigned Index = isa<ConstantInt>(ValIdx)
4051 ? cast<ConstantInt>(ValIdx)->getZExtValue()
4053 Type *PromotedType = getTransitionType();
4055 StoreInst *ST = cast<StoreInst>(CombineInst);
4056 unsigned AS = ST->getPointerAddressSpace();
4057 unsigned Align = ST->getAlignment();
4058 // Check if this store is supported.
4059 if (!TLI.allowsMisalignedMemoryAccesses(
4060 TLI.getValueType(ST->getValueOperand()->getType()), AS, Align)) {
4061 // If this is not supported, there is no way we can combine
4062 // the extract with the store.
4066 // The scalar chain of computation has to pay for the transition
4067 // scalar to vector.
4068 // The vector chain has to account for the combining cost.
4069 uint64_t ScalarCost =
4070 TTI.getVectorInstrCost(Transition->getOpcode(), PromotedType, Index);
4071 uint64_t VectorCost = StoreExtractCombineCost;
4072 for (const auto &Inst : InstsToBePromoted) {
4073 // Compute the cost.
4074 // By construction, all instructions being promoted are arithmetic ones.
4075 // Moreover, one argument is a constant that can be viewed as a splat
4077 Value *Arg0 = Inst->getOperand(0);
4078 bool IsArg0Constant = isa<UndefValue>(Arg0) || isa<ConstantInt>(Arg0) ||
4079 isa<ConstantFP>(Arg0);
4080 TargetTransformInfo::OperandValueKind Arg0OVK =
4081 IsArg0Constant ? TargetTransformInfo::OK_UniformConstantValue
4082 : TargetTransformInfo::OK_AnyValue;
4083 TargetTransformInfo::OperandValueKind Arg1OVK =
4084 !IsArg0Constant ? TargetTransformInfo::OK_UniformConstantValue
4085 : TargetTransformInfo::OK_AnyValue;
4086 ScalarCost += TTI.getArithmeticInstrCost(
4087 Inst->getOpcode(), Inst->getType(), Arg0OVK, Arg1OVK);
4088 VectorCost += TTI.getArithmeticInstrCost(Inst->getOpcode(), PromotedType,
4091 DEBUG(dbgs() << "Estimated cost of computation to be promoted:\nScalar: "
4092 << ScalarCost << "\nVector: " << VectorCost << '\n');
4093 return ScalarCost > VectorCost;
4096 /// \brief Generate a constant vector with \p Val with the same
4097 /// number of elements as the transition.
4098 /// \p UseSplat defines whether or not \p Val should be replicated
4099 /// accross the whole vector.
4100 /// In other words, if UseSplat == true, we generate <Val, Val, ..., Val>,
4101 /// otherwise we generate a vector with as many undef as possible:
4102 /// <undef, ..., undef, Val, undef, ..., undef> where \p Val is only
4103 /// used at the index of the extract.
4104 Value *getConstantVector(Constant *Val, bool UseSplat) const {
4105 unsigned ExtractIdx = UINT_MAX;
4107 // If we cannot determine where the constant must be, we have to
4108 // use a splat constant.
4109 Value *ValExtractIdx = Transition->getOperand(getTransitionIdx());
4110 if (ConstantInt *CstVal = dyn_cast<ConstantInt>(ValExtractIdx))
4111 ExtractIdx = CstVal->getSExtValue();
4116 unsigned End = getTransitionType()->getVectorNumElements();
4118 return ConstantVector::getSplat(End, Val);
4120 SmallVector<Constant *, 4> ConstVec;
4121 UndefValue *UndefVal = UndefValue::get(Val->getType());
4122 for (unsigned Idx = 0; Idx != End; ++Idx) {
4123 if (Idx == ExtractIdx)
4124 ConstVec.push_back(Val);
4126 ConstVec.push_back(UndefVal);
4128 return ConstantVector::get(ConstVec);
4131 /// \brief Check if promoting to a vector type an operand at \p OperandIdx
4132 /// in \p Use can trigger undefined behavior.
4133 static bool canCauseUndefinedBehavior(const Instruction *Use,
4134 unsigned OperandIdx) {
4135 // This is not safe to introduce undef when the operand is on
4136 // the right hand side of a division-like instruction.
4137 if (OperandIdx != 1)
4139 switch (Use->getOpcode()) {
4142 case Instruction::SDiv:
4143 case Instruction::UDiv:
4144 case Instruction::SRem:
4145 case Instruction::URem:
4147 case Instruction::FDiv:
4148 case Instruction::FRem:
4149 return !Use->hasNoNaNs();
4151 llvm_unreachable(nullptr);
4155 VectorPromoteHelper(const TargetLowering &TLI, const TargetTransformInfo &TTI,
4156 Instruction *Transition, unsigned CombineCost)
4157 : TLI(TLI), TTI(TTI), Transition(Transition),
4158 StoreExtractCombineCost(CombineCost), CombineInst(nullptr) {
4159 assert(Transition && "Do not know how to promote null");
4162 /// \brief Check if we can promote \p ToBePromoted to \p Type.
4163 bool canPromote(const Instruction *ToBePromoted) const {
4164 // We could support CastInst too.
4165 return isa<BinaryOperator>(ToBePromoted);
4168 /// \brief Check if it is profitable to promote \p ToBePromoted
4169 /// by moving downward the transition through.
4170 bool shouldPromote(const Instruction *ToBePromoted) const {
4171 // Promote only if all the operands can be statically expanded.
4172 // Indeed, we do not want to introduce any new kind of transitions.
4173 for (const Use &U : ToBePromoted->operands()) {
4174 const Value *Val = U.get();
4175 if (Val == getEndOfTransition()) {
4176 // If the use is a division and the transition is on the rhs,
4177 // we cannot promote the operation, otherwise we may create a
4178 // division by zero.
4179 if (canCauseUndefinedBehavior(ToBePromoted, U.getOperandNo()))
4183 if (!isa<ConstantInt>(Val) && !isa<UndefValue>(Val) &&
4184 !isa<ConstantFP>(Val))
4187 // Check that the resulting operation is legal.
4188 int ISDOpcode = TLI.InstructionOpcodeToISD(ToBePromoted->getOpcode());
4191 return StressStoreExtract ||
4192 TLI.isOperationLegalOrCustom(
4193 ISDOpcode, TLI.getValueType(getTransitionType(), true));
4196 /// \brief Check whether or not \p Use can be combined
4197 /// with the transition.
4198 /// I.e., is it possible to do Use(Transition) => AnotherUse?
4199 bool canCombine(const Instruction *Use) { return isa<StoreInst>(Use); }
4201 /// \brief Record \p ToBePromoted as part of the chain to be promoted.
4202 void enqueueForPromotion(Instruction *ToBePromoted) {
4203 InstsToBePromoted.push_back(ToBePromoted);
4206 /// \brief Set the instruction that will be combined with the transition.
4207 void recordCombineInstruction(Instruction *ToBeCombined) {
4208 assert(canCombine(ToBeCombined) && "Unsupported instruction to combine");
4209 CombineInst = ToBeCombined;
4212 /// \brief Promote all the instructions enqueued for promotion if it is
4214 /// \return True if the promotion happened, false otherwise.
4216 // Check if there is something to promote.
4217 // Right now, if we do not have anything to combine with,
4218 // we assume the promotion is not profitable.
4219 if (InstsToBePromoted.empty() || !CombineInst)
4223 if (!StressStoreExtract && !isProfitableToPromote())
4227 for (auto &ToBePromoted : InstsToBePromoted)
4228 promoteImpl(ToBePromoted);
4229 InstsToBePromoted.clear();
4233 } // End of anonymous namespace.
4235 void VectorPromoteHelper::promoteImpl(Instruction *ToBePromoted) {
4236 // At this point, we know that all the operands of ToBePromoted but Def
4237 // can be statically promoted.
4238 // For Def, we need to use its parameter in ToBePromoted:
4239 // b = ToBePromoted ty1 a
4240 // Def = Transition ty1 b to ty2
4241 // Move the transition down.
4242 // 1. Replace all uses of the promoted operation by the transition.
4243 // = ... b => = ... Def.
4244 assert(ToBePromoted->getType() == Transition->getType() &&
4245 "The type of the result of the transition does not match "
4247 ToBePromoted->replaceAllUsesWith(Transition);
4248 // 2. Update the type of the uses.
4249 // b = ToBePromoted ty2 Def => b = ToBePromoted ty1 Def.
4250 Type *TransitionTy = getTransitionType();
4251 ToBePromoted->mutateType(TransitionTy);
4252 // 3. Update all the operands of the promoted operation with promoted
4254 // b = ToBePromoted ty1 Def => b = ToBePromoted ty1 a.
4255 for (Use &U : ToBePromoted->operands()) {
4256 Value *Val = U.get();
4257 Value *NewVal = nullptr;
4258 if (Val == Transition)
4259 NewVal = Transition->getOperand(getTransitionOriginalValueIdx());
4260 else if (isa<UndefValue>(Val) || isa<ConstantInt>(Val) ||
4261 isa<ConstantFP>(Val)) {
4262 // Use a splat constant if it is not safe to use undef.
4263 NewVal = getConstantVector(
4264 cast<Constant>(Val),
4265 isa<UndefValue>(Val) ||
4266 canCauseUndefinedBehavior(ToBePromoted, U.getOperandNo()));
4268 llvm_unreachable("Did you modified shouldPromote and forgot to update "
4270 ToBePromoted->setOperand(U.getOperandNo(), NewVal);
4272 Transition->removeFromParent();
4273 Transition->insertAfter(ToBePromoted);
4274 Transition->setOperand(getTransitionOriginalValueIdx(), ToBePromoted);
4277 /// Some targets can do store(extractelement) with one instruction.
4278 /// Try to push the extractelement towards the stores when the target
4279 /// has this feature and this is profitable.
4280 bool CodeGenPrepare::OptimizeExtractElementInst(Instruction *Inst) {
4281 unsigned CombineCost = UINT_MAX;
4282 if (DisableStoreExtract || !TLI ||
4283 (!StressStoreExtract &&
4284 !TLI->canCombineStoreAndExtract(Inst->getOperand(0)->getType(),
4285 Inst->getOperand(1), CombineCost)))
4288 // At this point we know that Inst is a vector to scalar transition.
4289 // Try to move it down the def-use chain, until:
4290 // - We can combine the transition with its single use
4291 // => we got rid of the transition.
4292 // - We escape the current basic block
4293 // => we would need to check that we are moving it at a cheaper place and
4294 // we do not do that for now.
4295 BasicBlock *Parent = Inst->getParent();
4296 DEBUG(dbgs() << "Found an interesting transition: " << *Inst << '\n');
4297 VectorPromoteHelper VPH(*TLI, *TTI, Inst, CombineCost);
4298 // If the transition has more than one use, assume this is not going to be
4300 while (Inst->hasOneUse()) {
4301 Instruction *ToBePromoted = cast<Instruction>(*Inst->user_begin());
4302 DEBUG(dbgs() << "Use: " << *ToBePromoted << '\n');
4304 if (ToBePromoted->getParent() != Parent) {
4305 DEBUG(dbgs() << "Instruction to promote is in a different block ("
4306 << ToBePromoted->getParent()->getName()
4307 << ") than the transition (" << Parent->getName() << ").\n");
4311 if (VPH.canCombine(ToBePromoted)) {
4312 DEBUG(dbgs() << "Assume " << *Inst << '\n'
4313 << "will be combined with: " << *ToBePromoted << '\n');
4314 VPH.recordCombineInstruction(ToBePromoted);
4315 bool Changed = VPH.promote();
4316 NumStoreExtractExposed += Changed;
4320 DEBUG(dbgs() << "Try promoting.\n");
4321 if (!VPH.canPromote(ToBePromoted) || !VPH.shouldPromote(ToBePromoted))
4324 DEBUG(dbgs() << "Promoting is possible... Enqueue for promotion!\n");
4326 VPH.enqueueForPromotion(ToBePromoted);
4327 Inst = ToBePromoted;
4332 bool CodeGenPrepare::OptimizeInst(Instruction *I, bool& ModifiedDT) {
4333 if (PHINode *P = dyn_cast<PHINode>(I)) {
4334 // It is possible for very late stage optimizations (such as SimplifyCFG)
4335 // to introduce PHI nodes too late to be cleaned up. If we detect such a
4336 // trivial PHI, go ahead and zap it here.
4337 const DataLayout &DL = I->getModule()->getDataLayout();
4338 if (Value *V = SimplifyInstruction(P, DL, TLInfo, nullptr)) {
4339 P->replaceAllUsesWith(V);
4340 P->eraseFromParent();
4347 if (CastInst *CI = dyn_cast<CastInst>(I)) {
4348 // If the source of the cast is a constant, then this should have
4349 // already been constant folded. The only reason NOT to constant fold
4350 // it is if something (e.g. LSR) was careful to place the constant
4351 // evaluation in a block other than then one that uses it (e.g. to hoist
4352 // the address of globals out of a loop). If this is the case, we don't
4353 // want to forward-subst the cast.
4354 if (isa<Constant>(CI->getOperand(0)))
4357 if (TLI && OptimizeNoopCopyExpression(CI, *TLI))
4360 if (isa<ZExtInst>(I) || isa<SExtInst>(I)) {
4361 /// Sink a zext or sext into its user blocks if the target type doesn't
4362 /// fit in one register
4363 if (TLI && TLI->getTypeAction(CI->getContext(),
4364 TLI->getValueType(CI->getType())) ==
4365 TargetLowering::TypeExpandInteger) {
4366 return SinkCast(CI);
4368 bool MadeChange = MoveExtToFormExtLoad(I);
4369 return MadeChange | OptimizeExtUses(I);
4375 if (CmpInst *CI = dyn_cast<CmpInst>(I))
4376 if (!TLI || !TLI->hasMultipleConditionRegisters())
4377 return OptimizeCmpExpression(CI);
4379 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
4381 return OptimizeMemoryInst(I, I->getOperand(0), LI->getType());
4385 if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
4387 return OptimizeMemoryInst(I, SI->getOperand(1),
4388 SI->getOperand(0)->getType());
4392 BinaryOperator *BinOp = dyn_cast<BinaryOperator>(I);
4394 if (BinOp && (BinOp->getOpcode() == Instruction::AShr ||
4395 BinOp->getOpcode() == Instruction::LShr)) {
4396 ConstantInt *CI = dyn_cast<ConstantInt>(BinOp->getOperand(1));
4397 if (TLI && CI && TLI->hasExtractBitsInsn())
4398 return OptimizeExtractBits(BinOp, CI, *TLI);
4403 if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(I)) {
4404 if (GEPI->hasAllZeroIndices()) {
4405 /// The GEP operand must be a pointer, so must its result -> BitCast
4406 Instruction *NC = new BitCastInst(GEPI->getOperand(0), GEPI->getType(),
4407 GEPI->getName(), GEPI);
4408 GEPI->replaceAllUsesWith(NC);
4409 GEPI->eraseFromParent();
4411 OptimizeInst(NC, ModifiedDT);
4417 if (CallInst *CI = dyn_cast<CallInst>(I))
4418 return OptimizeCallInst(CI, ModifiedDT);
4420 if (SelectInst *SI = dyn_cast<SelectInst>(I))
4421 return OptimizeSelectInst(SI);
4423 if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(I))
4424 return OptimizeShuffleVectorInst(SVI);
4426 if (isa<ExtractElementInst>(I))
4427 return OptimizeExtractElementInst(I);
4432 // In this pass we look for GEP and cast instructions that are used
4433 // across basic blocks and rewrite them to improve basic-block-at-a-time
4435 bool CodeGenPrepare::OptimizeBlock(BasicBlock &BB, bool& ModifiedDT) {
4437 bool MadeChange = false;
4439 CurInstIterator = BB.begin();
4440 while (CurInstIterator != BB.end()) {
4441 MadeChange |= OptimizeInst(CurInstIterator++, ModifiedDT);
4445 MadeChange |= DupRetToEnableTailCallOpts(&BB);
4450 // llvm.dbg.value is far away from the value then iSel may not be able
4451 // handle it properly. iSel will drop llvm.dbg.value if it can not
4452 // find a node corresponding to the value.
4453 bool CodeGenPrepare::PlaceDbgValues(Function &F) {
4454 bool MadeChange = false;
4455 for (BasicBlock &BB : F) {
4456 Instruction *PrevNonDbgInst = nullptr;
4457 for (BasicBlock::iterator BI = BB.begin(), BE = BB.end(); BI != BE;) {
4458 Instruction *Insn = BI++;
4459 DbgValueInst *DVI = dyn_cast<DbgValueInst>(Insn);
4460 // Leave dbg.values that refer to an alloca alone. These
4461 // instrinsics describe the address of a variable (= the alloca)
4462 // being taken. They should not be moved next to the alloca
4463 // (and to the beginning of the scope), but rather stay close to
4464 // where said address is used.
4465 if (!DVI || (DVI->getValue() && isa<AllocaInst>(DVI->getValue()))) {
4466 PrevNonDbgInst = Insn;
4470 Instruction *VI = dyn_cast_or_null<Instruction>(DVI->getValue());
4471 if (VI && VI != PrevNonDbgInst && !VI->isTerminator()) {
4472 DEBUG(dbgs() << "Moving Debug Value before :\n" << *DVI << ' ' << *VI);
4473 DVI->removeFromParent();
4474 if (isa<PHINode>(VI))
4475 DVI->insertBefore(VI->getParent()->getFirstInsertionPt());
4477 DVI->insertAfter(VI);
4486 // If there is a sequence that branches based on comparing a single bit
4487 // against zero that can be combined into a single instruction, and the
4488 // target supports folding these into a single instruction, sink the
4489 // mask and compare into the branch uses. Do this before OptimizeBlock ->
4490 // OptimizeInst -> OptimizeCmpExpression, which perturbs the pattern being
4492 bool CodeGenPrepare::sinkAndCmp(Function &F) {
4493 if (!EnableAndCmpSinking)
4495 if (!TLI || !TLI->isMaskAndBranchFoldingLegal())
4497 bool MadeChange = false;
4498 for (Function::iterator I = F.begin(), E = F.end(); I != E; ) {
4499 BasicBlock *BB = I++;
4501 // Does this BB end with the following?
4502 // %andVal = and %val, #single-bit-set
4503 // %icmpVal = icmp %andResult, 0
4504 // br i1 %cmpVal label %dest1, label %dest2"
4505 BranchInst *Brcc = dyn_cast<BranchInst>(BB->getTerminator());
4506 if (!Brcc || !Brcc->isConditional())
4508 ICmpInst *Cmp = dyn_cast<ICmpInst>(Brcc->getOperand(0));
4509 if (!Cmp || Cmp->getParent() != BB)
4511 ConstantInt *Zero = dyn_cast<ConstantInt>(Cmp->getOperand(1));
4512 if (!Zero || !Zero->isZero())
4514 Instruction *And = dyn_cast<Instruction>(Cmp->getOperand(0));
4515 if (!And || And->getOpcode() != Instruction::And || And->getParent() != BB)
4517 ConstantInt* Mask = dyn_cast<ConstantInt>(And->getOperand(1));
4518 if (!Mask || !Mask->getUniqueInteger().isPowerOf2())
4520 DEBUG(dbgs() << "found and; icmp ?,0; brcc\n"); DEBUG(BB->dump());
4522 // Push the "and; icmp" for any users that are conditional branches.
4523 // Since there can only be one branch use per BB, we don't need to keep
4524 // track of which BBs we insert into.
4525 for (Value::use_iterator UI = Cmp->use_begin(), E = Cmp->use_end();
4529 BranchInst *BrccUser = dyn_cast<BranchInst>(*UI);
4531 if (!BrccUser || !BrccUser->isConditional())
4533 BasicBlock *UserBB = BrccUser->getParent();
4534 if (UserBB == BB) continue;
4535 DEBUG(dbgs() << "found Brcc use\n");
4537 // Sink the "and; icmp" to use.
4539 BinaryOperator *NewAnd =
4540 BinaryOperator::CreateAnd(And->getOperand(0), And->getOperand(1), "",
4543 CmpInst::Create(Cmp->getOpcode(), Cmp->getPredicate(), NewAnd, Zero,
4547 DEBUG(BrccUser->getParent()->dump());
4553 /// \brief Retrieve the probabilities of a conditional branch. Returns true on
4554 /// success, or returns false if no or invalid metadata was found.
4555 static bool extractBranchMetadata(BranchInst *BI,
4556 uint64_t &ProbTrue, uint64_t &ProbFalse) {
4557 assert(BI->isConditional() &&
4558 "Looking for probabilities on unconditional branch?");
4559 auto *ProfileData = BI->getMetadata(LLVMContext::MD_prof);
4560 if (!ProfileData || ProfileData->getNumOperands() != 3)
4563 const auto *CITrue =
4564 mdconst::dyn_extract<ConstantInt>(ProfileData->getOperand(1));
4565 const auto *CIFalse =
4566 mdconst::dyn_extract<ConstantInt>(ProfileData->getOperand(2));
4567 if (!CITrue || !CIFalse)
4570 ProbTrue = CITrue->getValue().getZExtValue();
4571 ProbFalse = CIFalse->getValue().getZExtValue();
4576 /// \brief Scale down both weights to fit into uint32_t.
4577 static void scaleWeights(uint64_t &NewTrue, uint64_t &NewFalse) {
4578 uint64_t NewMax = (NewTrue > NewFalse) ? NewTrue : NewFalse;
4579 uint32_t Scale = (NewMax / UINT32_MAX) + 1;
4580 NewTrue = NewTrue / Scale;
4581 NewFalse = NewFalse / Scale;
4584 /// \brief Some targets prefer to split a conditional branch like:
4586 /// %0 = icmp ne i32 %a, 0
4587 /// %1 = icmp ne i32 %b, 0
4588 /// %or.cond = or i1 %0, %1
4589 /// br i1 %or.cond, label %TrueBB, label %FalseBB
4591 /// into multiple branch instructions like:
4594 /// %0 = icmp ne i32 %a, 0
4595 /// br i1 %0, label %TrueBB, label %bb2
4597 /// %1 = icmp ne i32 %b, 0
4598 /// br i1 %1, label %TrueBB, label %FalseBB
4600 /// This usually allows instruction selection to do even further optimizations
4601 /// and combine the compare with the branch instruction. Currently this is
4602 /// applied for targets which have "cheap" jump instructions.
4604 /// FIXME: Remove the (equivalent?) implementation in SelectionDAG.
4606 bool CodeGenPrepare::splitBranchCondition(Function &F) {
4607 if (!TM || !TM->Options.EnableFastISel || !TLI || TLI->isJumpExpensive())
4610 bool MadeChange = false;
4611 for (auto &BB : F) {
4612 // Does this BB end with the following?
4613 // %cond1 = icmp|fcmp|binary instruction ...
4614 // %cond2 = icmp|fcmp|binary instruction ...
4615 // %cond.or = or|and i1 %cond1, cond2
4616 // br i1 %cond.or label %dest1, label %dest2"
4617 BinaryOperator *LogicOp;
4618 BasicBlock *TBB, *FBB;
4619 if (!match(BB.getTerminator(), m_Br(m_OneUse(m_BinOp(LogicOp)), TBB, FBB)))
4623 Value *Cond1, *Cond2;
4624 if (match(LogicOp, m_And(m_OneUse(m_Value(Cond1)),
4625 m_OneUse(m_Value(Cond2)))))
4626 Opc = Instruction::And;
4627 else if (match(LogicOp, m_Or(m_OneUse(m_Value(Cond1)),
4628 m_OneUse(m_Value(Cond2)))))
4629 Opc = Instruction::Or;
4633 if (!match(Cond1, m_CombineOr(m_Cmp(), m_BinOp())) ||
4634 !match(Cond2, m_CombineOr(m_Cmp(), m_BinOp())) )
4637 DEBUG(dbgs() << "Before branch condition splitting\n"; BB.dump());
4640 auto *InsertBefore = std::next(Function::iterator(BB))
4641 .getNodePtrUnchecked();
4642 auto TmpBB = BasicBlock::Create(BB.getContext(),
4643 BB.getName() + ".cond.split",
4644 BB.getParent(), InsertBefore);
4646 // Update original basic block by using the first condition directly by the
4647 // branch instruction and removing the no longer needed and/or instruction.
4648 auto *Br1 = cast<BranchInst>(BB.getTerminator());
4649 Br1->setCondition(Cond1);
4650 LogicOp->eraseFromParent();
4652 // Depending on the conditon we have to either replace the true or the false
4653 // successor of the original branch instruction.
4654 if (Opc == Instruction::And)
4655 Br1->setSuccessor(0, TmpBB);
4657 Br1->setSuccessor(1, TmpBB);
4659 // Fill in the new basic block.
4660 auto *Br2 = IRBuilder<>(TmpBB).CreateCondBr(Cond2, TBB, FBB);
4661 if (auto *I = dyn_cast<Instruction>(Cond2)) {
4662 I->removeFromParent();
4663 I->insertBefore(Br2);
4666 // Update PHI nodes in both successors. The original BB needs to be
4667 // replaced in one succesor's PHI nodes, because the branch comes now from
4668 // the newly generated BB (NewBB). In the other successor we need to add one
4669 // incoming edge to the PHI nodes, because both branch instructions target
4670 // now the same successor. Depending on the original branch condition
4671 // (and/or) we have to swap the successors (TrueDest, FalseDest), so that
4672 // we perfrom the correct update for the PHI nodes.
4673 // This doesn't change the successor order of the just created branch
4674 // instruction (or any other instruction).
4675 if (Opc == Instruction::Or)
4676 std::swap(TBB, FBB);
4678 // Replace the old BB with the new BB.
4679 for (auto &I : *TBB) {
4680 PHINode *PN = dyn_cast<PHINode>(&I);
4684 while ((i = PN->getBasicBlockIndex(&BB)) >= 0)
4685 PN->setIncomingBlock(i, TmpBB);
4688 // Add another incoming edge form the new BB.
4689 for (auto &I : *FBB) {
4690 PHINode *PN = dyn_cast<PHINode>(&I);
4693 auto *Val = PN->getIncomingValueForBlock(&BB);
4694 PN->addIncoming(Val, TmpBB);
4697 // Update the branch weights (from SelectionDAGBuilder::
4698 // FindMergedConditions).
4699 if (Opc == Instruction::Or) {
4700 // Codegen X | Y as:
4709 // We have flexibility in setting Prob for BB1 and Prob for NewBB.
4710 // The requirement is that
4711 // TrueProb for BB1 + (FalseProb for BB1 * TrueProb for TmpBB)
4712 // = TrueProb for orignal BB.
4713 // Assuming the orignal weights are A and B, one choice is to set BB1's
4714 // weights to A and A+2B, and set TmpBB's weights to A and 2B. This choice
4716 // TrueProb for BB1 == FalseProb for BB1 * TrueProb for TmpBB.
4717 // Another choice is to assume TrueProb for BB1 equals to TrueProb for
4718 // TmpBB, but the math is more complicated.
4719 uint64_t TrueWeight, FalseWeight;
4720 if (extractBranchMetadata(Br1, TrueWeight, FalseWeight)) {
4721 uint64_t NewTrueWeight = TrueWeight;
4722 uint64_t NewFalseWeight = TrueWeight + 2 * FalseWeight;
4723 scaleWeights(NewTrueWeight, NewFalseWeight);
4724 Br1->setMetadata(LLVMContext::MD_prof, MDBuilder(Br1->getContext())
4725 .createBranchWeights(TrueWeight, FalseWeight));
4727 NewTrueWeight = TrueWeight;
4728 NewFalseWeight = 2 * FalseWeight;
4729 scaleWeights(NewTrueWeight, NewFalseWeight);
4730 Br2->setMetadata(LLVMContext::MD_prof, MDBuilder(Br2->getContext())
4731 .createBranchWeights(TrueWeight, FalseWeight));
4734 // Codegen X & Y as:
4742 // This requires creation of TmpBB after CurBB.
4744 // We have flexibility in setting Prob for BB1 and Prob for TmpBB.
4745 // The requirement is that
4746 // FalseProb for BB1 + (TrueProb for BB1 * FalseProb for TmpBB)
4747 // = FalseProb for orignal BB.
4748 // Assuming the orignal weights are A and B, one choice is to set BB1's
4749 // weights to 2A+B and B, and set TmpBB's weights to 2A and B. This choice
4751 // FalseProb for BB1 == TrueProb for BB1 * FalseProb for TmpBB.
4752 uint64_t TrueWeight, FalseWeight;
4753 if (extractBranchMetadata(Br1, TrueWeight, FalseWeight)) {
4754 uint64_t NewTrueWeight = 2 * TrueWeight + FalseWeight;
4755 uint64_t NewFalseWeight = FalseWeight;
4756 scaleWeights(NewTrueWeight, NewFalseWeight);
4757 Br1->setMetadata(LLVMContext::MD_prof, MDBuilder(Br1->getContext())
4758 .createBranchWeights(TrueWeight, FalseWeight));
4760 NewTrueWeight = 2 * TrueWeight;
4761 NewFalseWeight = FalseWeight;
4762 scaleWeights(NewTrueWeight, NewFalseWeight);
4763 Br2->setMetadata(LLVMContext::MD_prof, MDBuilder(Br2->getContext())
4764 .createBranchWeights(TrueWeight, FalseWeight));
4768 // Note: No point in getting fancy here, since the DT info is never
4769 // available to CodeGenPrepare.
4774 DEBUG(dbgs() << "After branch condition splitting\n"; BB.dump();