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;
112 typedef PointerIntPair<Type *, 1, bool> TypeIsSExt;
113 typedef DenseMap<Instruction *, TypeIsSExt> InstrToOrigTy;
114 class TypePromotionTransaction;
116 class CodeGenPrepare : public FunctionPass {
117 const TargetMachine *TM;
118 const TargetLowering *TLI;
119 const TargetTransformInfo *TTI;
120 const TargetLibraryInfo *TLInfo;
122 /// As we scan instructions optimizing them, this is the next instruction
123 /// to optimize. Transforms that can invalidate this should update it.
124 BasicBlock::iterator CurInstIterator;
126 /// Keeps track of non-local addresses that have been sunk into a block.
127 /// This allows us to avoid inserting duplicate code for blocks with
128 /// multiple load/stores of the same address.
129 ValueMap<Value*, Value*> SunkAddrs;
131 /// Keeps track of all instructions inserted for the current function.
132 SetOfInstrs InsertedInsts;
133 /// Keeps track of the type of the related instruction before their
134 /// promotion for the current function.
135 InstrToOrigTy PromotedInsts;
137 /// True if CFG is modified in any way.
140 /// True if optimizing for size.
143 /// DataLayout for the Function being processed.
144 const DataLayout *DL;
147 static char ID; // Pass identification, replacement for typeid
148 explicit CodeGenPrepare(const TargetMachine *TM = nullptr)
149 : FunctionPass(ID), TM(TM), TLI(nullptr), TTI(nullptr), DL(nullptr) {
150 initializeCodeGenPreparePass(*PassRegistry::getPassRegistry());
152 bool runOnFunction(Function &F) override;
154 const char *getPassName() const override { return "CodeGen Prepare"; }
156 void getAnalysisUsage(AnalysisUsage &AU) const override {
157 AU.addPreserved<DominatorTreeWrapperPass>();
158 AU.addRequired<TargetLibraryInfoWrapperPass>();
159 AU.addRequired<TargetTransformInfoWrapperPass>();
163 bool eliminateFallThrough(Function &F);
164 bool eliminateMostlyEmptyBlocks(Function &F);
165 bool canMergeBlocks(const BasicBlock *BB, const BasicBlock *DestBB) const;
166 void eliminateMostlyEmptyBlock(BasicBlock *BB);
167 bool optimizeBlock(BasicBlock &BB, bool& ModifiedDT);
168 bool optimizeInst(Instruction *I, bool& ModifiedDT);
169 bool optimizeMemoryInst(Instruction *I, Value *Addr,
170 Type *AccessTy, unsigned AS);
171 bool optimizeInlineAsmInst(CallInst *CS);
172 bool optimizeCallInst(CallInst *CI, bool& ModifiedDT);
173 bool moveExtToFormExtLoad(Instruction *&I);
174 bool optimizeExtUses(Instruction *I);
175 bool optimizeSelectInst(SelectInst *SI);
176 bool optimizeShuffleVectorInst(ShuffleVectorInst *SI);
177 bool optimizeExtractElementInst(Instruction *Inst);
178 bool dupRetToEnableTailCallOpts(BasicBlock *BB);
179 bool placeDbgValues(Function &F);
180 bool sinkAndCmp(Function &F);
181 bool extLdPromotion(TypePromotionTransaction &TPT, LoadInst *&LI,
183 const SmallVectorImpl<Instruction *> &Exts,
184 unsigned CreatedInstCost);
185 bool splitBranchCondition(Function &F);
186 bool simplifyOffsetableRelocate(Instruction &I);
187 void stripInvariantGroupMetadata(Instruction &I);
191 char CodeGenPrepare::ID = 0;
192 INITIALIZE_TM_PASS(CodeGenPrepare, "codegenprepare",
193 "Optimize for code generation", false, false)
195 FunctionPass *llvm::createCodeGenPreparePass(const TargetMachine *TM) {
196 return new CodeGenPrepare(TM);
199 bool CodeGenPrepare::runOnFunction(Function &F) {
200 if (skipOptnoneFunction(F))
203 DL = &F.getParent()->getDataLayout();
205 bool EverMadeChange = false;
206 // Clear per function information.
207 InsertedInsts.clear();
208 PromotedInsts.clear();
212 TLI = TM->getSubtargetImpl(F)->getTargetLowering();
213 TLInfo = &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
214 TTI = &getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
215 OptSize = F.optForSize();
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 /// Merge basic blocks which are connected by a single edge, where one of the
312 /// basic blocks has a single successor pointing to the other basic block,
313 /// 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 /// Eliminate blocks that contain only PHI nodes, debug info directives, and an
346 /// unconditional branch. Passes before isel (e.g. LSR/loopsimplify) often split
347 /// edges in ways that are non-optimal for isel. Start by eliminating these
348 /// blocks so we can split them the way we want them.
349 bool CodeGenPrepare::eliminateMostlyEmptyBlocks(Function &F) {
350 bool MadeChange = false;
351 // Note that this intentionally skips the entry block.
352 for (Function::iterator I = std::next(F.begin()), E = F.end(); I != E;) {
353 BasicBlock *BB = I++;
355 // If this block doesn't end with an uncond branch, ignore it.
356 BranchInst *BI = dyn_cast<BranchInst>(BB->getTerminator());
357 if (!BI || !BI->isUnconditional())
360 // If the instruction before the branch (skipping debug info) isn't a phi
361 // node, then other stuff is happening here.
362 BasicBlock::iterator BBI = BI;
363 if (BBI != BB->begin()) {
365 while (isa<DbgInfoIntrinsic>(BBI)) {
366 if (BBI == BB->begin())
370 if (!isa<DbgInfoIntrinsic>(BBI) && !isa<PHINode>(BBI))
374 // Do not break infinite loops.
375 BasicBlock *DestBB = BI->getSuccessor(0);
379 if (!canMergeBlocks(BB, DestBB))
382 eliminateMostlyEmptyBlock(BB);
388 /// Return true if we can merge BB into DestBB if there is a single
389 /// unconditional branch between them, and BB contains no other non-phi
391 bool CodeGenPrepare::canMergeBlocks(const BasicBlock *BB,
392 const BasicBlock *DestBB) const {
393 // We only want to eliminate blocks whose phi nodes are used by phi nodes in
394 // the successor. If there are more complex condition (e.g. preheaders),
395 // don't mess around with them.
396 BasicBlock::const_iterator BBI = BB->begin();
397 while (const PHINode *PN = dyn_cast<PHINode>(BBI++)) {
398 for (const User *U : PN->users()) {
399 const Instruction *UI = cast<Instruction>(U);
400 if (UI->getParent() != DestBB || !isa<PHINode>(UI))
402 // If User is inside DestBB block and it is a PHINode then check
403 // incoming value. If incoming value is not from BB then this is
404 // a complex condition (e.g. preheaders) we want to avoid here.
405 if (UI->getParent() == DestBB) {
406 if (const PHINode *UPN = dyn_cast<PHINode>(UI))
407 for (unsigned I = 0, E = UPN->getNumIncomingValues(); I != E; ++I) {
408 Instruction *Insn = dyn_cast<Instruction>(UPN->getIncomingValue(I));
409 if (Insn && Insn->getParent() == BB &&
410 Insn->getParent() != UPN->getIncomingBlock(I))
417 // If BB and DestBB contain any common predecessors, then the phi nodes in BB
418 // and DestBB may have conflicting incoming values for the block. If so, we
419 // can't merge the block.
420 const PHINode *DestBBPN = dyn_cast<PHINode>(DestBB->begin());
421 if (!DestBBPN) return true; // no conflict.
423 // Collect the preds of BB.
424 SmallPtrSet<const BasicBlock*, 16> BBPreds;
425 if (const PHINode *BBPN = dyn_cast<PHINode>(BB->begin())) {
426 // It is faster to get preds from a PHI than with pred_iterator.
427 for (unsigned i = 0, e = BBPN->getNumIncomingValues(); i != e; ++i)
428 BBPreds.insert(BBPN->getIncomingBlock(i));
430 BBPreds.insert(pred_begin(BB), pred_end(BB));
433 // Walk the preds of DestBB.
434 for (unsigned i = 0, e = DestBBPN->getNumIncomingValues(); i != e; ++i) {
435 BasicBlock *Pred = DestBBPN->getIncomingBlock(i);
436 if (BBPreds.count(Pred)) { // Common predecessor?
437 BBI = DestBB->begin();
438 while (const PHINode *PN = dyn_cast<PHINode>(BBI++)) {
439 const Value *V1 = PN->getIncomingValueForBlock(Pred);
440 const Value *V2 = PN->getIncomingValueForBlock(BB);
442 // If V2 is a phi node in BB, look up what the mapped value will be.
443 if (const PHINode *V2PN = dyn_cast<PHINode>(V2))
444 if (V2PN->getParent() == BB)
445 V2 = V2PN->getIncomingValueForBlock(Pred);
447 // If there is a conflict, bail out.
448 if (V1 != V2) return false;
457 /// Eliminate a basic block that has only phi's and an unconditional branch in
459 void CodeGenPrepare::eliminateMostlyEmptyBlock(BasicBlock *BB) {
460 BranchInst *BI = cast<BranchInst>(BB->getTerminator());
461 BasicBlock *DestBB = BI->getSuccessor(0);
463 DEBUG(dbgs() << "MERGING MOSTLY EMPTY BLOCKS - BEFORE:\n" << *BB << *DestBB);
465 // If the destination block has a single pred, then this is a trivial edge,
467 if (BasicBlock *SinglePred = DestBB->getSinglePredecessor()) {
468 if (SinglePred != DestBB) {
469 // Remember if SinglePred was the entry block of the function. If so, we
470 // will need to move BB back to the entry position.
471 bool isEntry = SinglePred == &SinglePred->getParent()->getEntryBlock();
472 MergeBasicBlockIntoOnlyPred(DestBB, nullptr);
474 if (isEntry && BB != &BB->getParent()->getEntryBlock())
475 BB->moveBefore(&BB->getParent()->getEntryBlock());
477 DEBUG(dbgs() << "AFTER:\n" << *DestBB << "\n\n\n");
482 // Otherwise, we have multiple predecessors of BB. Update the PHIs in DestBB
483 // to handle the new incoming edges it is about to have.
485 for (BasicBlock::iterator BBI = DestBB->begin();
486 (PN = dyn_cast<PHINode>(BBI)); ++BBI) {
487 // Remove the incoming value for BB, and remember it.
488 Value *InVal = PN->removeIncomingValue(BB, false);
490 // Two options: either the InVal is a phi node defined in BB or it is some
491 // value that dominates BB.
492 PHINode *InValPhi = dyn_cast<PHINode>(InVal);
493 if (InValPhi && InValPhi->getParent() == BB) {
494 // Add all of the input values of the input PHI as inputs of this phi.
495 for (unsigned i = 0, e = InValPhi->getNumIncomingValues(); i != e; ++i)
496 PN->addIncoming(InValPhi->getIncomingValue(i),
497 InValPhi->getIncomingBlock(i));
499 // Otherwise, add one instance of the dominating value for each edge that
500 // we will be adding.
501 if (PHINode *BBPN = dyn_cast<PHINode>(BB->begin())) {
502 for (unsigned i = 0, e = BBPN->getNumIncomingValues(); i != e; ++i)
503 PN->addIncoming(InVal, BBPN->getIncomingBlock(i));
505 for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI)
506 PN->addIncoming(InVal, *PI);
511 // The PHIs are now updated, change everything that refers to BB to use
512 // DestBB and remove BB.
513 BB->replaceAllUsesWith(DestBB);
514 BB->eraseFromParent();
517 DEBUG(dbgs() << "AFTER:\n" << *DestBB << "\n\n\n");
520 // Computes a map of base pointer relocation instructions to corresponding
521 // derived pointer relocation instructions given a vector of all relocate calls
522 static void computeBaseDerivedRelocateMap(
523 const SmallVectorImpl<User *> &AllRelocateCalls,
524 DenseMap<IntrinsicInst *, SmallVector<IntrinsicInst *, 2>> &
526 // Collect information in two maps: one primarily for locating the base object
527 // while filling the second map; the second map is the final structure holding
528 // a mapping between Base and corresponding Derived relocate calls
529 DenseMap<std::pair<unsigned, unsigned>, IntrinsicInst *> RelocateIdxMap;
530 for (auto &U : AllRelocateCalls) {
531 GCRelocateOperands ThisRelocate(U);
532 IntrinsicInst *I = cast<IntrinsicInst>(U);
533 auto K = std::make_pair(ThisRelocate.getBasePtrIndex(),
534 ThisRelocate.getDerivedPtrIndex());
535 RelocateIdxMap.insert(std::make_pair(K, I));
537 for (auto &Item : RelocateIdxMap) {
538 std::pair<unsigned, unsigned> Key = Item.first;
539 if (Key.first == Key.second)
540 // Base relocation: nothing to insert
543 IntrinsicInst *I = Item.second;
544 auto BaseKey = std::make_pair(Key.first, Key.first);
546 // We're iterating over RelocateIdxMap so we cannot modify it.
547 auto MaybeBase = RelocateIdxMap.find(BaseKey);
548 if (MaybeBase == RelocateIdxMap.end())
549 // TODO: We might want to insert a new base object relocate and gep off
550 // that, if there are enough derived object relocates.
553 RelocateInstMap[MaybeBase->second].push_back(I);
557 // Accepts a GEP and extracts the operands into a vector provided they're all
558 // small integer constants
559 static bool getGEPSmallConstantIntOffsetV(GetElementPtrInst *GEP,
560 SmallVectorImpl<Value *> &OffsetV) {
561 for (unsigned i = 1; i < GEP->getNumOperands(); i++) {
562 // Only accept small constant integer operands
563 auto Op = dyn_cast<ConstantInt>(GEP->getOperand(i));
564 if (!Op || Op->getZExtValue() > 20)
568 for (unsigned i = 1; i < GEP->getNumOperands(); i++)
569 OffsetV.push_back(GEP->getOperand(i));
573 // Takes a RelocatedBase (base pointer relocation instruction) and Targets to
574 // replace, computes a replacement, and affects it.
576 simplifyRelocatesOffABase(IntrinsicInst *RelocatedBase,
577 const SmallVectorImpl<IntrinsicInst *> &Targets) {
578 bool MadeChange = false;
579 for (auto &ToReplace : Targets) {
580 GCRelocateOperands MasterRelocate(RelocatedBase);
581 GCRelocateOperands ThisRelocate(ToReplace);
583 assert(ThisRelocate.getBasePtrIndex() == MasterRelocate.getBasePtrIndex() &&
584 "Not relocating a derived object of the original base object");
585 if (ThisRelocate.getBasePtrIndex() == ThisRelocate.getDerivedPtrIndex()) {
586 // A duplicate relocate call. TODO: coalesce duplicates.
590 Value *Base = ThisRelocate.getBasePtr();
591 auto Derived = dyn_cast<GetElementPtrInst>(ThisRelocate.getDerivedPtr());
592 if (!Derived || Derived->getPointerOperand() != Base)
595 SmallVector<Value *, 2> OffsetV;
596 if (!getGEPSmallConstantIntOffsetV(Derived, OffsetV))
599 // Create a Builder and replace the target callsite with a gep
600 assert(RelocatedBase->getNextNode() && "Should always have one since it's not a terminator");
602 // Insert after RelocatedBase
603 IRBuilder<> Builder(RelocatedBase->getNextNode());
604 Builder.SetCurrentDebugLocation(ToReplace->getDebugLoc());
606 // If gc_relocate does not match the actual type, cast it to the right type.
607 // In theory, there must be a bitcast after gc_relocate if the type does not
608 // match, and we should reuse it to get the derived pointer. But it could be
612 // %g1 = call coldcc i8 addrspace(1)* @llvm.experimental.gc.relocate.p1i8(...)
617 // %g2 = call coldcc i8 addrspace(1)* @llvm.experimental.gc.relocate.p1i8(...)
621 // %p1 = phi i8 addrspace(1)* [ %g1, %bb1 ], [ %g2, %bb2 ]
622 // %cast = bitcast i8 addrspace(1)* %p1 in to i32 addrspace(1)*
624 // In this case, we can not find the bitcast any more. So we insert a new bitcast
625 // no matter there is already one or not. In this way, we can handle all cases, and
626 // the extra bitcast should be optimized away in later passes.
627 Instruction *ActualRelocatedBase = RelocatedBase;
628 if (RelocatedBase->getType() != Base->getType()) {
629 ActualRelocatedBase =
630 cast<Instruction>(Builder.CreateBitCast(RelocatedBase, Base->getType()));
632 Value *Replacement = Builder.CreateGEP(
633 Derived->getSourceElementType(), ActualRelocatedBase, makeArrayRef(OffsetV));
634 Instruction *ReplacementInst = cast<Instruction>(Replacement);
635 Replacement->takeName(ToReplace);
636 // If the newly generated derived pointer's type does not match the original derived
637 // pointer's type, cast the new derived pointer to match it. Same reasoning as above.
638 Instruction *ActualReplacement = ReplacementInst;
639 if (ReplacementInst->getType() != ToReplace->getType()) {
641 cast<Instruction>(Builder.CreateBitCast(ReplacementInst, ToReplace->getType()));
643 ToReplace->replaceAllUsesWith(ActualReplacement);
644 ToReplace->eraseFromParent();
654 // %ptr = gep %base + 15
655 // %tok = statepoint (%fun, i32 0, i32 0, i32 0, %base, %ptr)
656 // %base' = relocate(%tok, i32 4, i32 4)
657 // %ptr' = relocate(%tok, i32 4, i32 5)
663 // %ptr = gep %base + 15
664 // %tok = statepoint (%fun, i32 0, i32 0, i32 0, %base, %ptr)
665 // %base' = gc.relocate(%tok, i32 4, i32 4)
666 // %ptr' = gep %base' + 15
668 bool CodeGenPrepare::simplifyOffsetableRelocate(Instruction &I) {
669 bool MadeChange = false;
670 SmallVector<User *, 2> AllRelocateCalls;
672 for (auto *U : I.users())
673 if (isGCRelocate(dyn_cast<Instruction>(U)))
674 // Collect all the relocate calls associated with a statepoint
675 AllRelocateCalls.push_back(U);
677 // We need atleast one base pointer relocation + one derived pointer
678 // relocation to mangle
679 if (AllRelocateCalls.size() < 2)
682 // RelocateInstMap is a mapping from the base relocate instruction to the
683 // corresponding derived relocate instructions
684 DenseMap<IntrinsicInst *, SmallVector<IntrinsicInst *, 2>> RelocateInstMap;
685 computeBaseDerivedRelocateMap(AllRelocateCalls, RelocateInstMap);
686 if (RelocateInstMap.empty())
689 for (auto &Item : RelocateInstMap)
690 // Item.first is the RelocatedBase to offset against
691 // Item.second is the vector of Targets to replace
692 MadeChange = simplifyRelocatesOffABase(Item.first, Item.second);
696 /// SinkCast - Sink the specified cast instruction into its user blocks
697 static bool SinkCast(CastInst *CI) {
698 BasicBlock *DefBB = CI->getParent();
700 /// InsertedCasts - Only insert a cast in each block once.
701 DenseMap<BasicBlock*, CastInst*> InsertedCasts;
703 bool MadeChange = false;
704 for (Value::user_iterator UI = CI->user_begin(), E = CI->user_end();
706 Use &TheUse = UI.getUse();
707 Instruction *User = cast<Instruction>(*UI);
709 // Figure out which BB this cast is used in. For PHI's this is the
710 // appropriate predecessor block.
711 BasicBlock *UserBB = User->getParent();
712 if (PHINode *PN = dyn_cast<PHINode>(User)) {
713 UserBB = PN->getIncomingBlock(TheUse);
716 // Preincrement use iterator so we don't invalidate it.
719 // If this user is in the same block as the cast, don't change the cast.
720 if (UserBB == DefBB) continue;
722 // If we have already inserted a cast into this block, use it.
723 CastInst *&InsertedCast = InsertedCasts[UserBB];
726 BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
728 CastInst::Create(CI->getOpcode(), CI->getOperand(0), CI->getType(), "",
732 // Replace a use of the cast with a use of the new cast.
733 TheUse = InsertedCast;
738 // If we removed all uses, nuke the cast.
739 if (CI->use_empty()) {
740 CI->eraseFromParent();
747 /// If the specified cast instruction is a noop copy (e.g. it's casting from
748 /// one pointer type to another, i32->i8 on PPC), sink it into user blocks to
749 /// reduce the number of virtual registers that must be created and coalesced.
751 /// Return true if any changes are made.
753 static bool OptimizeNoopCopyExpression(CastInst *CI, const TargetLowering &TLI,
754 const DataLayout &DL) {
755 // If this is a noop copy,
756 EVT SrcVT = TLI.getValueType(DL, CI->getOperand(0)->getType());
757 EVT DstVT = TLI.getValueType(DL, CI->getType());
759 // This is an fp<->int conversion?
760 if (SrcVT.isInteger() != DstVT.isInteger())
763 // If this is an extension, it will be a zero or sign extension, which
765 if (SrcVT.bitsLT(DstVT)) return false;
767 // If these values will be promoted, find out what they will be promoted
768 // to. This helps us consider truncates on PPC as noop copies when they
770 if (TLI.getTypeAction(CI->getContext(), SrcVT) ==
771 TargetLowering::TypePromoteInteger)
772 SrcVT = TLI.getTypeToTransformTo(CI->getContext(), SrcVT);
773 if (TLI.getTypeAction(CI->getContext(), DstVT) ==
774 TargetLowering::TypePromoteInteger)
775 DstVT = TLI.getTypeToTransformTo(CI->getContext(), DstVT);
777 // If, after promotion, these are the same types, this is a noop copy.
784 /// Try to combine CI into a call to the llvm.uadd.with.overflow intrinsic if
787 /// Return true if any changes were made.
788 static bool CombineUAddWithOverflow(CmpInst *CI) {
792 m_UAddWithOverflow(m_Value(A), m_Value(B), m_Instruction(AddI))))
795 Type *Ty = AddI->getType();
796 if (!isa<IntegerType>(Ty))
799 // We don't want to move around uses of condition values this late, so we we
800 // check if it is legal to create the call to the intrinsic in the basic
801 // block containing the icmp:
803 if (AddI->getParent() != CI->getParent() && !AddI->hasOneUse())
807 // Someday m_UAddWithOverflow may get smarter, but this is a safe assumption
809 if (AddI->hasOneUse())
810 assert(*AddI->user_begin() == CI && "expected!");
813 Module *M = CI->getParent()->getParent()->getParent();
814 Value *F = Intrinsic::getDeclaration(M, Intrinsic::uadd_with_overflow, Ty);
816 auto *InsertPt = AddI->hasOneUse() ? CI : AddI;
818 auto *UAddWithOverflow =
819 CallInst::Create(F, {A, B}, "uadd.overflow", InsertPt);
820 auto *UAdd = ExtractValueInst::Create(UAddWithOverflow, 0, "uadd", InsertPt);
822 ExtractValueInst::Create(UAddWithOverflow, 1, "overflow", InsertPt);
824 CI->replaceAllUsesWith(Overflow);
825 AddI->replaceAllUsesWith(UAdd);
826 CI->eraseFromParent();
827 AddI->eraseFromParent();
831 /// Sink the given CmpInst into user blocks to reduce the number of virtual
832 /// registers that must be created and coalesced. This is a clear win except on
833 /// targets with multiple condition code registers (PowerPC), where it might
834 /// lose; some adjustment may be wanted there.
836 /// Return true if any changes are made.
837 static bool SinkCmpExpression(CmpInst *CI) {
838 BasicBlock *DefBB = CI->getParent();
840 /// Only insert a cmp in each block once.
841 DenseMap<BasicBlock*, CmpInst*> InsertedCmps;
843 bool MadeChange = false;
844 for (Value::user_iterator UI = CI->user_begin(), E = CI->user_end();
846 Use &TheUse = UI.getUse();
847 Instruction *User = cast<Instruction>(*UI);
849 // Preincrement use iterator so we don't invalidate it.
852 // Don't bother for PHI nodes.
853 if (isa<PHINode>(User))
856 // Figure out which BB this cmp is used in.
857 BasicBlock *UserBB = User->getParent();
859 // If this user is in the same block as the cmp, don't change the cmp.
860 if (UserBB == DefBB) continue;
862 // If we have already inserted a cmp into this block, use it.
863 CmpInst *&InsertedCmp = InsertedCmps[UserBB];
866 BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
868 CmpInst::Create(CI->getOpcode(),
869 CI->getPredicate(), CI->getOperand(0),
870 CI->getOperand(1), "", InsertPt);
873 // Replace a use of the cmp with a use of the new cmp.
874 TheUse = InsertedCmp;
879 // If we removed all uses, nuke the cmp.
880 if (CI->use_empty()) {
881 CI->eraseFromParent();
888 static bool OptimizeCmpExpression(CmpInst *CI) {
889 if (SinkCmpExpression(CI))
892 if (CombineUAddWithOverflow(CI))
898 /// Check if the candidates could be combined with a shift instruction, which
900 /// 1. Truncate instruction
901 /// 2. And instruction and the imm is a mask of the low bits:
902 /// imm & (imm+1) == 0
903 static bool isExtractBitsCandidateUse(Instruction *User) {
904 if (!isa<TruncInst>(User)) {
905 if (User->getOpcode() != Instruction::And ||
906 !isa<ConstantInt>(User->getOperand(1)))
909 const APInt &Cimm = cast<ConstantInt>(User->getOperand(1))->getValue();
911 if ((Cimm & (Cimm + 1)).getBoolValue())
917 /// Sink both shift and truncate instruction to the use of truncate's BB.
919 SinkShiftAndTruncate(BinaryOperator *ShiftI, Instruction *User, ConstantInt *CI,
920 DenseMap<BasicBlock *, BinaryOperator *> &InsertedShifts,
921 const TargetLowering &TLI, const DataLayout &DL) {
922 BasicBlock *UserBB = User->getParent();
923 DenseMap<BasicBlock *, CastInst *> InsertedTruncs;
924 TruncInst *TruncI = dyn_cast<TruncInst>(User);
925 bool MadeChange = false;
927 for (Value::user_iterator TruncUI = TruncI->user_begin(),
928 TruncE = TruncI->user_end();
929 TruncUI != TruncE;) {
931 Use &TruncTheUse = TruncUI.getUse();
932 Instruction *TruncUser = cast<Instruction>(*TruncUI);
933 // Preincrement use iterator so we don't invalidate it.
937 int ISDOpcode = TLI.InstructionOpcodeToISD(TruncUser->getOpcode());
941 // If the use is actually a legal node, there will not be an
942 // implicit truncate.
943 // FIXME: always querying the result type is just an
944 // approximation; some nodes' legality is determined by the
945 // operand or other means. There's no good way to find out though.
946 if (TLI.isOperationLegalOrCustom(
947 ISDOpcode, TLI.getValueType(DL, TruncUser->getType(), true)))
950 // Don't bother for PHI nodes.
951 if (isa<PHINode>(TruncUser))
954 BasicBlock *TruncUserBB = TruncUser->getParent();
956 if (UserBB == TruncUserBB)
959 BinaryOperator *&InsertedShift = InsertedShifts[TruncUserBB];
960 CastInst *&InsertedTrunc = InsertedTruncs[TruncUserBB];
962 if (!InsertedShift && !InsertedTrunc) {
963 BasicBlock::iterator InsertPt = TruncUserBB->getFirstInsertionPt();
965 if (ShiftI->getOpcode() == Instruction::AShr)
967 BinaryOperator::CreateAShr(ShiftI->getOperand(0), CI, "", InsertPt);
970 BinaryOperator::CreateLShr(ShiftI->getOperand(0), CI, "", InsertPt);
973 BasicBlock::iterator TruncInsertPt = TruncUserBB->getFirstInsertionPt();
976 InsertedTrunc = CastInst::Create(TruncI->getOpcode(), InsertedShift,
977 TruncI->getType(), "", TruncInsertPt);
981 TruncTheUse = InsertedTrunc;
987 /// Sink the shift *right* instruction into user blocks if the uses could
988 /// potentially be combined with this shift instruction and generate BitExtract
989 /// instruction. It will only be applied if the architecture supports BitExtract
990 /// instruction. Here is an example:
992 /// %x.extract.shift = lshr i64 %arg1, 32
994 /// %x.extract.trunc = trunc i64 %x.extract.shift to i16
998 /// %x.extract.shift.1 = lshr i64 %arg1, 32
999 /// %x.extract.trunc = trunc i64 %x.extract.shift.1 to i16
1001 /// CodeGen will recoginze the pattern in BB2 and generate BitExtract
1003 /// Return true if any changes are made.
1004 static bool OptimizeExtractBits(BinaryOperator *ShiftI, ConstantInt *CI,
1005 const TargetLowering &TLI,
1006 const DataLayout &DL) {
1007 BasicBlock *DefBB = ShiftI->getParent();
1009 /// Only insert instructions in each block once.
1010 DenseMap<BasicBlock *, BinaryOperator *> InsertedShifts;
1012 bool shiftIsLegal = TLI.isTypeLegal(TLI.getValueType(DL, ShiftI->getType()));
1014 bool MadeChange = false;
1015 for (Value::user_iterator UI = ShiftI->user_begin(), E = ShiftI->user_end();
1017 Use &TheUse = UI.getUse();
1018 Instruction *User = cast<Instruction>(*UI);
1019 // Preincrement use iterator so we don't invalidate it.
1022 // Don't bother for PHI nodes.
1023 if (isa<PHINode>(User))
1026 if (!isExtractBitsCandidateUse(User))
1029 BasicBlock *UserBB = User->getParent();
1031 if (UserBB == DefBB) {
1032 // If the shift and truncate instruction are in the same BB. The use of
1033 // the truncate(TruncUse) may still introduce another truncate if not
1034 // legal. In this case, we would like to sink both shift and truncate
1035 // instruction to the BB of TruncUse.
1038 // i64 shift.result = lshr i64 opnd, imm
1039 // trunc.result = trunc shift.result to i16
1042 // ----> We will have an implicit truncate here if the architecture does
1043 // not have i16 compare.
1044 // cmp i16 trunc.result, opnd2
1046 if (isa<TruncInst>(User) && shiftIsLegal
1047 // If the type of the truncate is legal, no trucate will be
1048 // introduced in other basic blocks.
1050 (!TLI.isTypeLegal(TLI.getValueType(DL, User->getType()))))
1052 SinkShiftAndTruncate(ShiftI, User, CI, InsertedShifts, TLI, DL);
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 // Translate a 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, with 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 // Translate a 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 // Align the pointer arguments to this call if the target thinks it's a good
1311 unsigned MinSize, PrefAlign;
1312 if (TLI && TLI->shouldAlignPointerArgs(CI, MinSize, PrefAlign)) {
1313 for (auto &Arg : CI->arg_operands()) {
1314 // We want to align both objects whose address is used directly and
1315 // objects whose address is used in casts and GEPs, though it only makes
1316 // sense for GEPs if the offset is a multiple of the desired alignment and
1317 // if size - offset meets the size threshold.
1318 if (!Arg->getType()->isPointerTy())
1320 APInt Offset(DL->getPointerSizeInBits(
1321 cast<PointerType>(Arg->getType())->getAddressSpace()),
1323 Value *Val = Arg->stripAndAccumulateInBoundsConstantOffsets(*DL, Offset);
1324 uint64_t Offset2 = Offset.getLimitedValue();
1325 if ((Offset2 & (PrefAlign-1)) != 0)
1328 if ((AI = dyn_cast<AllocaInst>(Val)) && AI->getAlignment() < PrefAlign &&
1329 DL->getTypeAllocSize(AI->getAllocatedType()) >= MinSize + Offset2)
1330 AI->setAlignment(PrefAlign);
1331 // Global variables can only be aligned if they are defined in this
1332 // object (i.e. they are uniquely initialized in this object), and
1333 // over-aligning global variables that have an explicit section is
1336 if ((GV = dyn_cast<GlobalVariable>(Val)) && GV->hasUniqueInitializer() &&
1337 !GV->hasSection() && GV->getAlignment() < PrefAlign &&
1338 DL->getTypeAllocSize(GV->getType()->getElementType()) >=
1340 GV->setAlignment(PrefAlign);
1342 // If this is a memcpy (or similar) then we may be able to improve the
1344 if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(CI)) {
1345 unsigned Align = getKnownAlignment(MI->getDest(), *DL);
1346 if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(MI))
1347 Align = std::min(Align, getKnownAlignment(MTI->getSource(), *DL));
1348 if (Align > MI->getAlignment())
1349 MI->setAlignment(ConstantInt::get(MI->getAlignmentType(), Align));
1353 IntrinsicInst *II = dyn_cast<IntrinsicInst>(CI);
1355 switch (II->getIntrinsicID()) {
1357 case Intrinsic::objectsize: {
1358 // Lower all uses of llvm.objectsize.*
1359 bool Min = (cast<ConstantInt>(II->getArgOperand(1))->getZExtValue() == 1);
1360 Type *ReturnTy = CI->getType();
1361 Constant *RetVal = ConstantInt::get(ReturnTy, Min ? 0 : -1ULL);
1363 // Substituting this can cause recursive simplifications, which can
1364 // invalidate our iterator. Use a WeakVH to hold onto it in case this
1366 WeakVH IterHandle(CurInstIterator);
1368 replaceAndRecursivelySimplify(CI, RetVal,
1371 // If the iterator instruction was recursively deleted, start over at the
1372 // start of the block.
1373 if (IterHandle != CurInstIterator) {
1374 CurInstIterator = BB->begin();
1379 case Intrinsic::masked_load: {
1380 // Scalarize unsupported vector masked load
1381 if (!TTI->isLegalMaskedLoad(CI->getType(), 1)) {
1382 ScalarizeMaskedLoad(CI);
1388 case Intrinsic::masked_store: {
1389 if (!TTI->isLegalMaskedStore(CI->getArgOperand(0)->getType(), 1)) {
1390 ScalarizeMaskedStore(CI);
1396 case Intrinsic::aarch64_stlxr:
1397 case Intrinsic::aarch64_stxr: {
1398 ZExtInst *ExtVal = dyn_cast<ZExtInst>(CI->getArgOperand(0));
1399 if (!ExtVal || !ExtVal->hasOneUse() ||
1400 ExtVal->getParent() == CI->getParent())
1402 // Sink a zext feeding stlxr/stxr before it, so it can be folded into it.
1403 ExtVal->moveBefore(CI);
1404 // Mark this instruction as "inserted by CGP", so that other
1405 // optimizations don't touch it.
1406 InsertedInsts.insert(ExtVal);
1409 case Intrinsic::invariant_group_barrier:
1410 II->replaceAllUsesWith(II->getArgOperand(0));
1411 II->eraseFromParent();
1416 // Unknown address space.
1417 // TODO: Target hook to pick which address space the intrinsic cares
1419 unsigned AddrSpace = ~0u;
1420 SmallVector<Value*, 2> PtrOps;
1422 if (TLI->GetAddrModeArguments(II, PtrOps, AccessTy, AddrSpace))
1423 while (!PtrOps.empty())
1424 if (optimizeMemoryInst(II, PtrOps.pop_back_val(), AccessTy, AddrSpace))
1429 // From here on out we're working with named functions.
1430 if (!CI->getCalledFunction()) return false;
1432 // Lower all default uses of _chk calls. This is very similar
1433 // to what InstCombineCalls does, but here we are only lowering calls
1434 // to fortified library functions (e.g. __memcpy_chk) that have the default
1435 // "don't know" as the objectsize. Anything else should be left alone.
1436 FortifiedLibCallSimplifier Simplifier(TLInfo, true);
1437 if (Value *V = Simplifier.optimizeCall(CI)) {
1438 CI->replaceAllUsesWith(V);
1439 CI->eraseFromParent();
1445 /// Look for opportunities to duplicate return instructions to the predecessor
1446 /// to enable tail call optimizations. The case it is currently looking for is:
1449 /// %tmp0 = tail call i32 @f0()
1450 /// br label %return
1452 /// %tmp1 = tail call i32 @f1()
1453 /// br label %return
1455 /// %tmp2 = tail call i32 @f2()
1456 /// br label %return
1458 /// %retval = phi i32 [ %tmp0, %bb0 ], [ %tmp1, %bb1 ], [ %tmp2, %bb2 ]
1466 /// %tmp0 = tail call i32 @f0()
1469 /// %tmp1 = tail call i32 @f1()
1472 /// %tmp2 = tail call i32 @f2()
1475 bool CodeGenPrepare::dupRetToEnableTailCallOpts(BasicBlock *BB) {
1479 ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator());
1483 PHINode *PN = nullptr;
1484 BitCastInst *BCI = nullptr;
1485 Value *V = RI->getReturnValue();
1487 BCI = dyn_cast<BitCastInst>(V);
1489 V = BCI->getOperand(0);
1491 PN = dyn_cast<PHINode>(V);
1496 if (PN && PN->getParent() != BB)
1499 // It's not safe to eliminate the sign / zero extension of the return value.
1500 // See llvm::isInTailCallPosition().
1501 const Function *F = BB->getParent();
1502 AttributeSet CallerAttrs = F->getAttributes();
1503 if (CallerAttrs.hasAttribute(AttributeSet::ReturnIndex, Attribute::ZExt) ||
1504 CallerAttrs.hasAttribute(AttributeSet::ReturnIndex, Attribute::SExt))
1507 // Make sure there are no instructions between the PHI and return, or that the
1508 // return is the first instruction in the block.
1510 BasicBlock::iterator BI = BB->begin();
1511 do { ++BI; } while (isa<DbgInfoIntrinsic>(BI));
1513 // Also skip over the bitcast.
1518 BasicBlock::iterator BI = BB->begin();
1519 while (isa<DbgInfoIntrinsic>(BI)) ++BI;
1524 /// Only dup the ReturnInst if the CallInst is likely to be emitted as a tail
1526 SmallVector<CallInst*, 4> TailCalls;
1528 for (unsigned I = 0, E = PN->getNumIncomingValues(); I != E; ++I) {
1529 CallInst *CI = dyn_cast<CallInst>(PN->getIncomingValue(I));
1530 // Make sure the phi value is indeed produced by the tail call.
1531 if (CI && CI->hasOneUse() && CI->getParent() == PN->getIncomingBlock(I) &&
1532 TLI->mayBeEmittedAsTailCall(CI))
1533 TailCalls.push_back(CI);
1536 SmallPtrSet<BasicBlock*, 4> VisitedBBs;
1537 for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB); PI != PE; ++PI) {
1538 if (!VisitedBBs.insert(*PI).second)
1541 BasicBlock::InstListType &InstList = (*PI)->getInstList();
1542 BasicBlock::InstListType::reverse_iterator RI = InstList.rbegin();
1543 BasicBlock::InstListType::reverse_iterator RE = InstList.rend();
1544 do { ++RI; } while (RI != RE && isa<DbgInfoIntrinsic>(&*RI));
1548 CallInst *CI = dyn_cast<CallInst>(&*RI);
1549 if (CI && CI->use_empty() && TLI->mayBeEmittedAsTailCall(CI))
1550 TailCalls.push_back(CI);
1554 bool Changed = false;
1555 for (unsigned i = 0, e = TailCalls.size(); i != e; ++i) {
1556 CallInst *CI = TailCalls[i];
1559 // Conservatively require the attributes of the call to match those of the
1560 // return. Ignore noalias because it doesn't affect the call sequence.
1561 AttributeSet CalleeAttrs = CS.getAttributes();
1562 if (AttrBuilder(CalleeAttrs, AttributeSet::ReturnIndex).
1563 removeAttribute(Attribute::NoAlias) !=
1564 AttrBuilder(CalleeAttrs, AttributeSet::ReturnIndex).
1565 removeAttribute(Attribute::NoAlias))
1568 // Make sure the call instruction is followed by an unconditional branch to
1569 // the return block.
1570 BasicBlock *CallBB = CI->getParent();
1571 BranchInst *BI = dyn_cast<BranchInst>(CallBB->getTerminator());
1572 if (!BI || !BI->isUnconditional() || BI->getSuccessor(0) != BB)
1575 // Duplicate the return into CallBB.
1576 (void)FoldReturnIntoUncondBranch(RI, BB, CallBB);
1577 ModifiedDT = Changed = true;
1581 // If we eliminated all predecessors of the block, delete the block now.
1582 if (Changed && !BB->hasAddressTaken() && pred_begin(BB) == pred_end(BB))
1583 BB->eraseFromParent();
1588 //===----------------------------------------------------------------------===//
1589 // Memory Optimization
1590 //===----------------------------------------------------------------------===//
1594 /// This is an extended version of TargetLowering::AddrMode
1595 /// which holds actual Value*'s for register values.
1596 struct ExtAddrMode : public TargetLowering::AddrMode {
1599 ExtAddrMode() : BaseReg(nullptr), ScaledReg(nullptr) {}
1600 void print(raw_ostream &OS) const;
1603 bool operator==(const ExtAddrMode& O) const {
1604 return (BaseReg == O.BaseReg) && (ScaledReg == O.ScaledReg) &&
1605 (BaseGV == O.BaseGV) && (BaseOffs == O.BaseOffs) &&
1606 (HasBaseReg == O.HasBaseReg) && (Scale == O.Scale);
1611 static inline raw_ostream &operator<<(raw_ostream &OS, const ExtAddrMode &AM) {
1617 void ExtAddrMode::print(raw_ostream &OS) const {
1618 bool NeedPlus = false;
1621 OS << (NeedPlus ? " + " : "")
1623 BaseGV->printAsOperand(OS, /*PrintType=*/false);
1628 OS << (NeedPlus ? " + " : "")
1634 OS << (NeedPlus ? " + " : "")
1636 BaseReg->printAsOperand(OS, /*PrintType=*/false);
1640 OS << (NeedPlus ? " + " : "")
1642 ScaledReg->printAsOperand(OS, /*PrintType=*/false);
1648 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
1649 void ExtAddrMode::dump() const {
1655 /// \brief This class provides transaction based operation on the IR.
1656 /// Every change made through this class is recorded in the internal state and
1657 /// can be undone (rollback) until commit is called.
1658 class TypePromotionTransaction {
1660 /// \brief This represents the common interface of the individual transaction.
1661 /// Each class implements the logic for doing one specific modification on
1662 /// the IR via the TypePromotionTransaction.
1663 class TypePromotionAction {
1665 /// The Instruction modified.
1669 /// \brief Constructor of the action.
1670 /// The constructor performs the related action on the IR.
1671 TypePromotionAction(Instruction *Inst) : Inst(Inst) {}
1673 virtual ~TypePromotionAction() {}
1675 /// \brief Undo the modification done by this action.
1676 /// When this method is called, the IR must be in the same state as it was
1677 /// before this action was applied.
1678 /// \pre Undoing the action works if and only if the IR is in the exact same
1679 /// state as it was directly after this action was applied.
1680 virtual void undo() = 0;
1682 /// \brief Advocate every change made by this action.
1683 /// When the results on the IR of the action are to be kept, it is important
1684 /// to call this function, otherwise hidden information may be kept forever.
1685 virtual void commit() {
1686 // Nothing to be done, this action is not doing anything.
1690 /// \brief Utility to remember the position of an instruction.
1691 class InsertionHandler {
1692 /// Position of an instruction.
1693 /// Either an instruction:
1694 /// - Is the first in a basic block: BB is used.
1695 /// - Has a previous instructon: PrevInst is used.
1697 Instruction *PrevInst;
1700 /// Remember whether or not the instruction had a previous instruction.
1701 bool HasPrevInstruction;
1704 /// \brief Record the position of \p Inst.
1705 InsertionHandler(Instruction *Inst) {
1706 BasicBlock::iterator It = Inst;
1707 HasPrevInstruction = (It != (Inst->getParent()->begin()));
1708 if (HasPrevInstruction)
1709 Point.PrevInst = --It;
1711 Point.BB = Inst->getParent();
1714 /// \brief Insert \p Inst at the recorded position.
1715 void insert(Instruction *Inst) {
1716 if (HasPrevInstruction) {
1717 if (Inst->getParent())
1718 Inst->removeFromParent();
1719 Inst->insertAfter(Point.PrevInst);
1721 Instruction *Position = Point.BB->getFirstInsertionPt();
1722 if (Inst->getParent())
1723 Inst->moveBefore(Position);
1725 Inst->insertBefore(Position);
1730 /// \brief Move an instruction before another.
1731 class InstructionMoveBefore : public TypePromotionAction {
1732 /// Original position of the instruction.
1733 InsertionHandler Position;
1736 /// \brief Move \p Inst before \p Before.
1737 InstructionMoveBefore(Instruction *Inst, Instruction *Before)
1738 : TypePromotionAction(Inst), Position(Inst) {
1739 DEBUG(dbgs() << "Do: move: " << *Inst << "\nbefore: " << *Before << "\n");
1740 Inst->moveBefore(Before);
1743 /// \brief Move the instruction back to its original position.
1744 void undo() override {
1745 DEBUG(dbgs() << "Undo: moveBefore: " << *Inst << "\n");
1746 Position.insert(Inst);
1750 /// \brief Set the operand of an instruction with a new value.
1751 class OperandSetter : public TypePromotionAction {
1752 /// Original operand of the instruction.
1754 /// Index of the modified instruction.
1758 /// \brief Set \p Idx operand of \p Inst with \p NewVal.
1759 OperandSetter(Instruction *Inst, unsigned Idx, Value *NewVal)
1760 : TypePromotionAction(Inst), Idx(Idx) {
1761 DEBUG(dbgs() << "Do: setOperand: " << Idx << "\n"
1762 << "for:" << *Inst << "\n"
1763 << "with:" << *NewVal << "\n");
1764 Origin = Inst->getOperand(Idx);
1765 Inst->setOperand(Idx, NewVal);
1768 /// \brief Restore the original value of the instruction.
1769 void undo() override {
1770 DEBUG(dbgs() << "Undo: setOperand:" << Idx << "\n"
1771 << "for: " << *Inst << "\n"
1772 << "with: " << *Origin << "\n");
1773 Inst->setOperand(Idx, Origin);
1777 /// \brief Hide the operands of an instruction.
1778 /// Do as if this instruction was not using any of its operands.
1779 class OperandsHider : public TypePromotionAction {
1780 /// The list of original operands.
1781 SmallVector<Value *, 4> OriginalValues;
1784 /// \brief Remove \p Inst from the uses of the operands of \p Inst.
1785 OperandsHider(Instruction *Inst) : TypePromotionAction(Inst) {
1786 DEBUG(dbgs() << "Do: OperandsHider: " << *Inst << "\n");
1787 unsigned NumOpnds = Inst->getNumOperands();
1788 OriginalValues.reserve(NumOpnds);
1789 for (unsigned It = 0; It < NumOpnds; ++It) {
1790 // Save the current operand.
1791 Value *Val = Inst->getOperand(It);
1792 OriginalValues.push_back(Val);
1794 // We could use OperandSetter here, but that would imply an overhead
1795 // that we are not willing to pay.
1796 Inst->setOperand(It, UndefValue::get(Val->getType()));
1800 /// \brief Restore the original list of uses.
1801 void undo() override {
1802 DEBUG(dbgs() << "Undo: OperandsHider: " << *Inst << "\n");
1803 for (unsigned It = 0, EndIt = OriginalValues.size(); It != EndIt; ++It)
1804 Inst->setOperand(It, OriginalValues[It]);
1808 /// \brief Build a truncate instruction.
1809 class TruncBuilder : public TypePromotionAction {
1812 /// \brief Build a truncate instruction of \p Opnd producing a \p Ty
1814 /// trunc Opnd to Ty.
1815 TruncBuilder(Instruction *Opnd, Type *Ty) : TypePromotionAction(Opnd) {
1816 IRBuilder<> Builder(Opnd);
1817 Val = Builder.CreateTrunc(Opnd, Ty, "promoted");
1818 DEBUG(dbgs() << "Do: TruncBuilder: " << *Val << "\n");
1821 /// \brief Get the built value.
1822 Value *getBuiltValue() { return Val; }
1824 /// \brief Remove the built instruction.
1825 void undo() override {
1826 DEBUG(dbgs() << "Undo: TruncBuilder: " << *Val << "\n");
1827 if (Instruction *IVal = dyn_cast<Instruction>(Val))
1828 IVal->eraseFromParent();
1832 /// \brief Build a sign extension instruction.
1833 class SExtBuilder : public TypePromotionAction {
1836 /// \brief Build a sign extension instruction of \p Opnd producing a \p Ty
1838 /// sext Opnd to Ty.
1839 SExtBuilder(Instruction *InsertPt, Value *Opnd, Type *Ty)
1840 : TypePromotionAction(InsertPt) {
1841 IRBuilder<> Builder(InsertPt);
1842 Val = Builder.CreateSExt(Opnd, Ty, "promoted");
1843 DEBUG(dbgs() << "Do: SExtBuilder: " << *Val << "\n");
1846 /// \brief Get the built value.
1847 Value *getBuiltValue() { return Val; }
1849 /// \brief Remove the built instruction.
1850 void undo() override {
1851 DEBUG(dbgs() << "Undo: SExtBuilder: " << *Val << "\n");
1852 if (Instruction *IVal = dyn_cast<Instruction>(Val))
1853 IVal->eraseFromParent();
1857 /// \brief Build a zero extension instruction.
1858 class ZExtBuilder : public TypePromotionAction {
1861 /// \brief Build a zero extension instruction of \p Opnd producing a \p Ty
1863 /// zext Opnd to Ty.
1864 ZExtBuilder(Instruction *InsertPt, Value *Opnd, Type *Ty)
1865 : TypePromotionAction(InsertPt) {
1866 IRBuilder<> Builder(InsertPt);
1867 Val = Builder.CreateZExt(Opnd, Ty, "promoted");
1868 DEBUG(dbgs() << "Do: ZExtBuilder: " << *Val << "\n");
1871 /// \brief Get the built value.
1872 Value *getBuiltValue() { return Val; }
1874 /// \brief Remove the built instruction.
1875 void undo() override {
1876 DEBUG(dbgs() << "Undo: ZExtBuilder: " << *Val << "\n");
1877 if (Instruction *IVal = dyn_cast<Instruction>(Val))
1878 IVal->eraseFromParent();
1882 /// \brief Mutate an instruction to another type.
1883 class TypeMutator : public TypePromotionAction {
1884 /// Record the original type.
1888 /// \brief Mutate the type of \p Inst into \p NewTy.
1889 TypeMutator(Instruction *Inst, Type *NewTy)
1890 : TypePromotionAction(Inst), OrigTy(Inst->getType()) {
1891 DEBUG(dbgs() << "Do: MutateType: " << *Inst << " with " << *NewTy
1893 Inst->mutateType(NewTy);
1896 /// \brief Mutate the instruction back to its original type.
1897 void undo() override {
1898 DEBUG(dbgs() << "Undo: MutateType: " << *Inst << " with " << *OrigTy
1900 Inst->mutateType(OrigTy);
1904 /// \brief Replace the uses of an instruction by another instruction.
1905 class UsesReplacer : public TypePromotionAction {
1906 /// Helper structure to keep track of the replaced uses.
1907 struct InstructionAndIdx {
1908 /// The instruction using the instruction.
1910 /// The index where this instruction is used for Inst.
1912 InstructionAndIdx(Instruction *Inst, unsigned Idx)
1913 : Inst(Inst), Idx(Idx) {}
1916 /// Keep track of the original uses (pair Instruction, Index).
1917 SmallVector<InstructionAndIdx, 4> OriginalUses;
1918 typedef SmallVectorImpl<InstructionAndIdx>::iterator use_iterator;
1921 /// \brief Replace all the use of \p Inst by \p New.
1922 UsesReplacer(Instruction *Inst, Value *New) : TypePromotionAction(Inst) {
1923 DEBUG(dbgs() << "Do: UsersReplacer: " << *Inst << " with " << *New
1925 // Record the original uses.
1926 for (Use &U : Inst->uses()) {
1927 Instruction *UserI = cast<Instruction>(U.getUser());
1928 OriginalUses.push_back(InstructionAndIdx(UserI, U.getOperandNo()));
1930 // Now, we can replace the uses.
1931 Inst->replaceAllUsesWith(New);
1934 /// \brief Reassign the original uses of Inst to Inst.
1935 void undo() override {
1936 DEBUG(dbgs() << "Undo: UsersReplacer: " << *Inst << "\n");
1937 for (use_iterator UseIt = OriginalUses.begin(),
1938 EndIt = OriginalUses.end();
1939 UseIt != EndIt; ++UseIt) {
1940 UseIt->Inst->setOperand(UseIt->Idx, Inst);
1945 /// \brief Remove an instruction from the IR.
1946 class InstructionRemover : public TypePromotionAction {
1947 /// Original position of the instruction.
1948 InsertionHandler Inserter;
1949 /// Helper structure to hide all the link to the instruction. In other
1950 /// words, this helps to do as if the instruction was removed.
1951 OperandsHider Hider;
1952 /// Keep track of the uses replaced, if any.
1953 UsesReplacer *Replacer;
1956 /// \brief Remove all reference of \p Inst and optinally replace all its
1958 /// \pre If !Inst->use_empty(), then New != nullptr
1959 InstructionRemover(Instruction *Inst, Value *New = nullptr)
1960 : TypePromotionAction(Inst), Inserter(Inst), Hider(Inst),
1963 Replacer = new UsesReplacer(Inst, New);
1964 DEBUG(dbgs() << "Do: InstructionRemover: " << *Inst << "\n");
1965 Inst->removeFromParent();
1968 ~InstructionRemover() override { delete Replacer; }
1970 /// \brief Really remove the instruction.
1971 void commit() override { delete Inst; }
1973 /// \brief Resurrect the instruction and reassign it to the proper uses if
1974 /// new value was provided when build this action.
1975 void undo() override {
1976 DEBUG(dbgs() << "Undo: InstructionRemover: " << *Inst << "\n");
1977 Inserter.insert(Inst);
1985 /// Restoration point.
1986 /// The restoration point is a pointer to an action instead of an iterator
1987 /// because the iterator may be invalidated but not the pointer.
1988 typedef const TypePromotionAction *ConstRestorationPt;
1989 /// Advocate every changes made in that transaction.
1991 /// Undo all the changes made after the given point.
1992 void rollback(ConstRestorationPt Point);
1993 /// Get the current restoration point.
1994 ConstRestorationPt getRestorationPoint() const;
1996 /// \name API for IR modification with state keeping to support rollback.
1998 /// Same as Instruction::setOperand.
1999 void setOperand(Instruction *Inst, unsigned Idx, Value *NewVal);
2000 /// Same as Instruction::eraseFromParent.
2001 void eraseInstruction(Instruction *Inst, Value *NewVal = nullptr);
2002 /// Same as Value::replaceAllUsesWith.
2003 void replaceAllUsesWith(Instruction *Inst, Value *New);
2004 /// Same as Value::mutateType.
2005 void mutateType(Instruction *Inst, Type *NewTy);
2006 /// Same as IRBuilder::createTrunc.
2007 Value *createTrunc(Instruction *Opnd, Type *Ty);
2008 /// Same as IRBuilder::createSExt.
2009 Value *createSExt(Instruction *Inst, Value *Opnd, Type *Ty);
2010 /// Same as IRBuilder::createZExt.
2011 Value *createZExt(Instruction *Inst, Value *Opnd, Type *Ty);
2012 /// Same as Instruction::moveBefore.
2013 void moveBefore(Instruction *Inst, Instruction *Before);
2017 /// The ordered list of actions made so far.
2018 SmallVector<std::unique_ptr<TypePromotionAction>, 16> Actions;
2019 typedef SmallVectorImpl<std::unique_ptr<TypePromotionAction>>::iterator CommitPt;
2022 void TypePromotionTransaction::setOperand(Instruction *Inst, unsigned Idx,
2025 make_unique<TypePromotionTransaction::OperandSetter>(Inst, Idx, NewVal));
2028 void TypePromotionTransaction::eraseInstruction(Instruction *Inst,
2031 make_unique<TypePromotionTransaction::InstructionRemover>(Inst, NewVal));
2034 void TypePromotionTransaction::replaceAllUsesWith(Instruction *Inst,
2036 Actions.push_back(make_unique<TypePromotionTransaction::UsesReplacer>(Inst, New));
2039 void TypePromotionTransaction::mutateType(Instruction *Inst, Type *NewTy) {
2040 Actions.push_back(make_unique<TypePromotionTransaction::TypeMutator>(Inst, NewTy));
2043 Value *TypePromotionTransaction::createTrunc(Instruction *Opnd,
2045 std::unique_ptr<TruncBuilder> Ptr(new TruncBuilder(Opnd, Ty));
2046 Value *Val = Ptr->getBuiltValue();
2047 Actions.push_back(std::move(Ptr));
2051 Value *TypePromotionTransaction::createSExt(Instruction *Inst,
2052 Value *Opnd, Type *Ty) {
2053 std::unique_ptr<SExtBuilder> Ptr(new SExtBuilder(Inst, Opnd, Ty));
2054 Value *Val = Ptr->getBuiltValue();
2055 Actions.push_back(std::move(Ptr));
2059 Value *TypePromotionTransaction::createZExt(Instruction *Inst,
2060 Value *Opnd, Type *Ty) {
2061 std::unique_ptr<ZExtBuilder> Ptr(new ZExtBuilder(Inst, Opnd, Ty));
2062 Value *Val = Ptr->getBuiltValue();
2063 Actions.push_back(std::move(Ptr));
2067 void TypePromotionTransaction::moveBefore(Instruction *Inst,
2068 Instruction *Before) {
2070 make_unique<TypePromotionTransaction::InstructionMoveBefore>(Inst, Before));
2073 TypePromotionTransaction::ConstRestorationPt
2074 TypePromotionTransaction::getRestorationPoint() const {
2075 return !Actions.empty() ? Actions.back().get() : nullptr;
2078 void TypePromotionTransaction::commit() {
2079 for (CommitPt It = Actions.begin(), EndIt = Actions.end(); It != EndIt;
2085 void TypePromotionTransaction::rollback(
2086 TypePromotionTransaction::ConstRestorationPt Point) {
2087 while (!Actions.empty() && Point != Actions.back().get()) {
2088 std::unique_ptr<TypePromotionAction> Curr = Actions.pop_back_val();
2093 /// \brief A helper class for matching addressing modes.
2095 /// This encapsulates the logic for matching the target-legal addressing modes.
2096 class AddressingModeMatcher {
2097 SmallVectorImpl<Instruction*> &AddrModeInsts;
2098 const TargetMachine &TM;
2099 const TargetLowering &TLI;
2100 const DataLayout &DL;
2102 /// AccessTy/MemoryInst - This is the type for the access (e.g. double) and
2103 /// the memory instruction that we're computing this address for.
2106 Instruction *MemoryInst;
2108 /// This is the addressing mode that we're building up. This is
2109 /// part of the return value of this addressing mode matching stuff.
2110 ExtAddrMode &AddrMode;
2112 /// The instructions inserted by other CodeGenPrepare optimizations.
2113 const SetOfInstrs &InsertedInsts;
2114 /// A map from the instructions to their type before promotion.
2115 InstrToOrigTy &PromotedInsts;
2116 /// The ongoing transaction where every action should be registered.
2117 TypePromotionTransaction &TPT;
2119 /// This is set to true when we should not do profitability checks.
2120 /// When true, IsProfitableToFoldIntoAddressingMode always returns true.
2121 bool IgnoreProfitability;
2123 AddressingModeMatcher(SmallVectorImpl<Instruction *> &AMI,
2124 const TargetMachine &TM, Type *AT, unsigned AS,
2125 Instruction *MI, ExtAddrMode &AM,
2126 const SetOfInstrs &InsertedInsts,
2127 InstrToOrigTy &PromotedInsts,
2128 TypePromotionTransaction &TPT)
2129 : AddrModeInsts(AMI), TM(TM),
2130 TLI(*TM.getSubtargetImpl(*MI->getParent()->getParent())
2131 ->getTargetLowering()),
2132 DL(MI->getModule()->getDataLayout()), AccessTy(AT), AddrSpace(AS),
2133 MemoryInst(MI), AddrMode(AM), InsertedInsts(InsertedInsts),
2134 PromotedInsts(PromotedInsts), TPT(TPT) {
2135 IgnoreProfitability = false;
2139 /// Find the maximal addressing mode that a load/store of V can fold,
2140 /// give an access type of AccessTy. This returns a list of involved
2141 /// instructions in AddrModeInsts.
2142 /// \p InsertedInsts The instructions inserted by other CodeGenPrepare
2144 /// \p PromotedInsts maps the instructions to their type before promotion.
2145 /// \p The ongoing transaction where every action should be registered.
2146 static ExtAddrMode Match(Value *V, Type *AccessTy, unsigned AS,
2147 Instruction *MemoryInst,
2148 SmallVectorImpl<Instruction*> &AddrModeInsts,
2149 const TargetMachine &TM,
2150 const SetOfInstrs &InsertedInsts,
2151 InstrToOrigTy &PromotedInsts,
2152 TypePromotionTransaction &TPT) {
2155 bool Success = AddressingModeMatcher(AddrModeInsts, TM, AccessTy, AS,
2156 MemoryInst, Result, InsertedInsts,
2157 PromotedInsts, TPT).matchAddr(V, 0);
2158 (void)Success; assert(Success && "Couldn't select *anything*?");
2162 bool matchScaledValue(Value *ScaleReg, int64_t Scale, unsigned Depth);
2163 bool matchAddr(Value *V, unsigned Depth);
2164 bool matchOperationAddr(User *Operation, unsigned Opcode, unsigned Depth,
2165 bool *MovedAway = nullptr);
2166 bool isProfitableToFoldIntoAddressingMode(Instruction *I,
2167 ExtAddrMode &AMBefore,
2168 ExtAddrMode &AMAfter);
2169 bool valueAlreadyLiveAtInst(Value *Val, Value *KnownLive1, Value *KnownLive2);
2170 bool isPromotionProfitable(unsigned NewCost, unsigned OldCost,
2171 Value *PromotedOperand) const;
2174 /// Try adding ScaleReg*Scale to the current addressing mode.
2175 /// Return true and update AddrMode if this addr mode is legal for the target,
2177 bool AddressingModeMatcher::matchScaledValue(Value *ScaleReg, int64_t Scale,
2179 // If Scale is 1, then this is the same as adding ScaleReg to the addressing
2180 // mode. Just process that directly.
2182 return matchAddr(ScaleReg, Depth);
2184 // If the scale is 0, it takes nothing to add this.
2188 // If we already have a scale of this value, we can add to it, otherwise, we
2189 // need an available scale field.
2190 if (AddrMode.Scale != 0 && AddrMode.ScaledReg != ScaleReg)
2193 ExtAddrMode TestAddrMode = AddrMode;
2195 // Add scale to turn X*4+X*3 -> X*7. This could also do things like
2196 // [A+B + A*7] -> [B+A*8].
2197 TestAddrMode.Scale += Scale;
2198 TestAddrMode.ScaledReg = ScaleReg;
2200 // If the new address isn't legal, bail out.
2201 if (!TLI.isLegalAddressingMode(DL, TestAddrMode, AccessTy, AddrSpace))
2204 // It was legal, so commit it.
2205 AddrMode = TestAddrMode;
2207 // Okay, we decided that we can add ScaleReg+Scale to AddrMode. Check now
2208 // to see if ScaleReg is actually X+C. If so, we can turn this into adding
2209 // X*Scale + C*Scale to addr mode.
2210 ConstantInt *CI = nullptr; Value *AddLHS = nullptr;
2211 if (isa<Instruction>(ScaleReg) && // not a constant expr.
2212 match(ScaleReg, m_Add(m_Value(AddLHS), m_ConstantInt(CI)))) {
2213 TestAddrMode.ScaledReg = AddLHS;
2214 TestAddrMode.BaseOffs += CI->getSExtValue()*TestAddrMode.Scale;
2216 // If this addressing mode is legal, commit it and remember that we folded
2217 // this instruction.
2218 if (TLI.isLegalAddressingMode(DL, TestAddrMode, AccessTy, AddrSpace)) {
2219 AddrModeInsts.push_back(cast<Instruction>(ScaleReg));
2220 AddrMode = TestAddrMode;
2225 // Otherwise, not (x+c)*scale, just return what we have.
2229 /// This is a little filter, which returns true if an addressing computation
2230 /// involving I might be folded into a load/store accessing it.
2231 /// This doesn't need to be perfect, but needs to accept at least
2232 /// the set of instructions that MatchOperationAddr can.
2233 static bool MightBeFoldableInst(Instruction *I) {
2234 switch (I->getOpcode()) {
2235 case Instruction::BitCast:
2236 case Instruction::AddrSpaceCast:
2237 // Don't touch identity bitcasts.
2238 if (I->getType() == I->getOperand(0)->getType())
2240 return I->getType()->isPointerTy() || I->getType()->isIntegerTy();
2241 case Instruction::PtrToInt:
2242 // PtrToInt is always a noop, as we know that the int type is pointer sized.
2244 case Instruction::IntToPtr:
2245 // We know the input is intptr_t, so this is foldable.
2247 case Instruction::Add:
2249 case Instruction::Mul:
2250 case Instruction::Shl:
2251 // Can only handle X*C and X << C.
2252 return isa<ConstantInt>(I->getOperand(1));
2253 case Instruction::GetElementPtr:
2260 /// \brief Check whether or not \p Val is a legal instruction for \p TLI.
2261 /// \note \p Val is assumed to be the product of some type promotion.
2262 /// Therefore if \p Val has an undefined state in \p TLI, this is assumed
2263 /// to be legal, as the non-promoted value would have had the same state.
2264 static bool isPromotedInstructionLegal(const TargetLowering &TLI,
2265 const DataLayout &DL, Value *Val) {
2266 Instruction *PromotedInst = dyn_cast<Instruction>(Val);
2269 int ISDOpcode = TLI.InstructionOpcodeToISD(PromotedInst->getOpcode());
2270 // If the ISDOpcode is undefined, it was undefined before the promotion.
2273 // Otherwise, check if the promoted instruction is legal or not.
2274 return TLI.isOperationLegalOrCustom(
2275 ISDOpcode, TLI.getValueType(DL, PromotedInst->getType()));
2278 /// \brief Hepler class to perform type promotion.
2279 class TypePromotionHelper {
2280 /// \brief Utility function to check whether or not a sign or zero extension
2281 /// of \p Inst with \p ConsideredExtType can be moved through \p Inst by
2282 /// either using the operands of \p Inst or promoting \p Inst.
2283 /// The type of the extension is defined by \p IsSExt.
2284 /// In other words, check if:
2285 /// ext (Ty Inst opnd1 opnd2 ... opndN) to ConsideredExtType.
2286 /// #1 Promotion applies:
2287 /// ConsideredExtType Inst (ext opnd1 to ConsideredExtType, ...).
2288 /// #2 Operand reuses:
2289 /// ext opnd1 to ConsideredExtType.
2290 /// \p PromotedInsts maps the instructions to their type before promotion.
2291 static bool canGetThrough(const Instruction *Inst, Type *ConsideredExtType,
2292 const InstrToOrigTy &PromotedInsts, bool IsSExt);
2294 /// \brief Utility function to determine if \p OpIdx should be promoted when
2295 /// promoting \p Inst.
2296 static bool shouldExtOperand(const Instruction *Inst, int OpIdx) {
2297 if (isa<SelectInst>(Inst) && OpIdx == 0)
2302 /// \brief Utility function to promote the operand of \p Ext when this
2303 /// operand is a promotable trunc or sext or zext.
2304 /// \p PromotedInsts maps the instructions to their type before promotion.
2305 /// \p CreatedInstsCost[out] contains the cost of all instructions
2306 /// created to promote the operand of Ext.
2307 /// Newly added extensions are inserted in \p Exts.
2308 /// Newly added truncates are inserted in \p Truncs.
2309 /// Should never be called directly.
2310 /// \return The promoted value which is used instead of Ext.
2311 static Value *promoteOperandForTruncAndAnyExt(
2312 Instruction *Ext, TypePromotionTransaction &TPT,
2313 InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
2314 SmallVectorImpl<Instruction *> *Exts,
2315 SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI);
2317 /// \brief Utility function to promote the operand of \p Ext when this
2318 /// operand is promotable and is not a supported trunc or sext.
2319 /// \p PromotedInsts maps the instructions to their type before promotion.
2320 /// \p CreatedInstsCost[out] contains the cost of all the instructions
2321 /// created to promote the operand of Ext.
2322 /// Newly added extensions are inserted in \p Exts.
2323 /// Newly added truncates are inserted in \p Truncs.
2324 /// Should never be called directly.
2325 /// \return The promoted value which is used instead of Ext.
2326 static Value *promoteOperandForOther(Instruction *Ext,
2327 TypePromotionTransaction &TPT,
2328 InstrToOrigTy &PromotedInsts,
2329 unsigned &CreatedInstsCost,
2330 SmallVectorImpl<Instruction *> *Exts,
2331 SmallVectorImpl<Instruction *> *Truncs,
2332 const TargetLowering &TLI, bool IsSExt);
2334 /// \see promoteOperandForOther.
2335 static Value *signExtendOperandForOther(
2336 Instruction *Ext, TypePromotionTransaction &TPT,
2337 InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
2338 SmallVectorImpl<Instruction *> *Exts,
2339 SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI) {
2340 return promoteOperandForOther(Ext, TPT, PromotedInsts, CreatedInstsCost,
2341 Exts, Truncs, TLI, true);
2344 /// \see promoteOperandForOther.
2345 static Value *zeroExtendOperandForOther(
2346 Instruction *Ext, TypePromotionTransaction &TPT,
2347 InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
2348 SmallVectorImpl<Instruction *> *Exts,
2349 SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI) {
2350 return promoteOperandForOther(Ext, TPT, PromotedInsts, CreatedInstsCost,
2351 Exts, Truncs, TLI, false);
2355 /// Type for the utility function that promotes the operand of Ext.
2356 typedef Value *(*Action)(Instruction *Ext, TypePromotionTransaction &TPT,
2357 InstrToOrigTy &PromotedInsts,
2358 unsigned &CreatedInstsCost,
2359 SmallVectorImpl<Instruction *> *Exts,
2360 SmallVectorImpl<Instruction *> *Truncs,
2361 const TargetLowering &TLI);
2362 /// \brief Given a sign/zero extend instruction \p Ext, return the approriate
2363 /// action to promote the operand of \p Ext instead of using Ext.
2364 /// \return NULL if no promotable action is possible with the current
2366 /// \p InsertedInsts keeps track of all the instructions inserted by the
2367 /// other CodeGenPrepare optimizations. This information is important
2368 /// because we do not want to promote these instructions as CodeGenPrepare
2369 /// will reinsert them later. Thus creating an infinite loop: create/remove.
2370 /// \p PromotedInsts maps the instructions to their type before promotion.
2371 static Action getAction(Instruction *Ext, const SetOfInstrs &InsertedInsts,
2372 const TargetLowering &TLI,
2373 const InstrToOrigTy &PromotedInsts);
2376 bool TypePromotionHelper::canGetThrough(const Instruction *Inst,
2377 Type *ConsideredExtType,
2378 const InstrToOrigTy &PromotedInsts,
2380 // The promotion helper does not know how to deal with vector types yet.
2381 // To be able to fix that, we would need to fix the places where we
2382 // statically extend, e.g., constants and such.
2383 if (Inst->getType()->isVectorTy())
2386 // We can always get through zext.
2387 if (isa<ZExtInst>(Inst))
2390 // sext(sext) is ok too.
2391 if (IsSExt && isa<SExtInst>(Inst))
2394 // We can get through binary operator, if it is legal. In other words, the
2395 // binary operator must have a nuw or nsw flag.
2396 const BinaryOperator *BinOp = dyn_cast<BinaryOperator>(Inst);
2397 if (BinOp && isa<OverflowingBinaryOperator>(BinOp) &&
2398 ((!IsSExt && BinOp->hasNoUnsignedWrap()) ||
2399 (IsSExt && BinOp->hasNoSignedWrap())))
2402 // Check if we can do the following simplification.
2403 // ext(trunc(opnd)) --> ext(opnd)
2404 if (!isa<TruncInst>(Inst))
2407 Value *OpndVal = Inst->getOperand(0);
2408 // Check if we can use this operand in the extension.
2409 // If the type is larger than the result type of the extension, we cannot.
2410 if (!OpndVal->getType()->isIntegerTy() ||
2411 OpndVal->getType()->getIntegerBitWidth() >
2412 ConsideredExtType->getIntegerBitWidth())
2415 // If the operand of the truncate is not an instruction, we will not have
2416 // any information on the dropped bits.
2417 // (Actually we could for constant but it is not worth the extra logic).
2418 Instruction *Opnd = dyn_cast<Instruction>(OpndVal);
2422 // Check if the source of the type is narrow enough.
2423 // I.e., check that trunc just drops extended bits of the same kind of
2425 // #1 get the type of the operand and check the kind of the extended bits.
2426 const Type *OpndType;
2427 InstrToOrigTy::const_iterator It = PromotedInsts.find(Opnd);
2428 if (It != PromotedInsts.end() && It->second.getInt() == IsSExt)
2429 OpndType = It->second.getPointer();
2430 else if ((IsSExt && isa<SExtInst>(Opnd)) || (!IsSExt && isa<ZExtInst>(Opnd)))
2431 OpndType = Opnd->getOperand(0)->getType();
2435 // #2 check that the truncate just drops extended bits.
2436 if (Inst->getType()->getIntegerBitWidth() >= OpndType->getIntegerBitWidth())
2442 TypePromotionHelper::Action TypePromotionHelper::getAction(
2443 Instruction *Ext, const SetOfInstrs &InsertedInsts,
2444 const TargetLowering &TLI, const InstrToOrigTy &PromotedInsts) {
2445 assert((isa<SExtInst>(Ext) || isa<ZExtInst>(Ext)) &&
2446 "Unexpected instruction type");
2447 Instruction *ExtOpnd = dyn_cast<Instruction>(Ext->getOperand(0));
2448 Type *ExtTy = Ext->getType();
2449 bool IsSExt = isa<SExtInst>(Ext);
2450 // If the operand of the extension is not an instruction, we cannot
2452 // If it, check we can get through.
2453 if (!ExtOpnd || !canGetThrough(ExtOpnd, ExtTy, PromotedInsts, IsSExt))
2456 // Do not promote if the operand has been added by codegenprepare.
2457 // Otherwise, it means we are undoing an optimization that is likely to be
2458 // redone, thus causing potential infinite loop.
2459 if (isa<TruncInst>(ExtOpnd) && InsertedInsts.count(ExtOpnd))
2462 // SExt or Trunc instructions.
2463 // Return the related handler.
2464 if (isa<SExtInst>(ExtOpnd) || isa<TruncInst>(ExtOpnd) ||
2465 isa<ZExtInst>(ExtOpnd))
2466 return promoteOperandForTruncAndAnyExt;
2468 // Regular instruction.
2469 // Abort early if we will have to insert non-free instructions.
2470 if (!ExtOpnd->hasOneUse() && !TLI.isTruncateFree(ExtTy, ExtOpnd->getType()))
2472 return IsSExt ? signExtendOperandForOther : zeroExtendOperandForOther;
2475 Value *TypePromotionHelper::promoteOperandForTruncAndAnyExt(
2476 llvm::Instruction *SExt, TypePromotionTransaction &TPT,
2477 InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
2478 SmallVectorImpl<Instruction *> *Exts,
2479 SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI) {
2480 // By construction, the operand of SExt is an instruction. Otherwise we cannot
2481 // get through it and this method should not be called.
2482 Instruction *SExtOpnd = cast<Instruction>(SExt->getOperand(0));
2483 Value *ExtVal = SExt;
2484 bool HasMergedNonFreeExt = false;
2485 if (isa<ZExtInst>(SExtOpnd)) {
2486 // Replace s|zext(zext(opnd))
2488 HasMergedNonFreeExt = !TLI.isExtFree(SExtOpnd);
2490 TPT.createZExt(SExt, SExtOpnd->getOperand(0), SExt->getType());
2491 TPT.replaceAllUsesWith(SExt, ZExt);
2492 TPT.eraseInstruction(SExt);
2495 // Replace z|sext(trunc(opnd)) or sext(sext(opnd))
2497 TPT.setOperand(SExt, 0, SExtOpnd->getOperand(0));
2499 CreatedInstsCost = 0;
2501 // Remove dead code.
2502 if (SExtOpnd->use_empty())
2503 TPT.eraseInstruction(SExtOpnd);
2505 // Check if the extension is still needed.
2506 Instruction *ExtInst = dyn_cast<Instruction>(ExtVal);
2507 if (!ExtInst || ExtInst->getType() != ExtInst->getOperand(0)->getType()) {
2510 Exts->push_back(ExtInst);
2511 CreatedInstsCost = !TLI.isExtFree(ExtInst) && !HasMergedNonFreeExt;
2516 // At this point we have: ext ty opnd to ty.
2517 // Reassign the uses of ExtInst to the opnd and remove ExtInst.
2518 Value *NextVal = ExtInst->getOperand(0);
2519 TPT.eraseInstruction(ExtInst, NextVal);
2523 Value *TypePromotionHelper::promoteOperandForOther(
2524 Instruction *Ext, TypePromotionTransaction &TPT,
2525 InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
2526 SmallVectorImpl<Instruction *> *Exts,
2527 SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI,
2529 // By construction, the operand of Ext is an instruction. Otherwise we cannot
2530 // get through it and this method should not be called.
2531 Instruction *ExtOpnd = cast<Instruction>(Ext->getOperand(0));
2532 CreatedInstsCost = 0;
2533 if (!ExtOpnd->hasOneUse()) {
2534 // ExtOpnd will be promoted.
2535 // All its uses, but Ext, will need to use a truncated value of the
2536 // promoted version.
2537 // Create the truncate now.
2538 Value *Trunc = TPT.createTrunc(Ext, ExtOpnd->getType());
2539 if (Instruction *ITrunc = dyn_cast<Instruction>(Trunc)) {
2540 ITrunc->removeFromParent();
2541 // Insert it just after the definition.
2542 ITrunc->insertAfter(ExtOpnd);
2544 Truncs->push_back(ITrunc);
2547 TPT.replaceAllUsesWith(ExtOpnd, Trunc);
2548 // Restore the operand of Ext (which has been replaced by the previous call
2549 // to replaceAllUsesWith) to avoid creating a cycle trunc <-> sext.
2550 TPT.setOperand(Ext, 0, ExtOpnd);
2553 // Get through the Instruction:
2554 // 1. Update its type.
2555 // 2. Replace the uses of Ext by Inst.
2556 // 3. Extend each operand that needs to be extended.
2558 // Remember the original type of the instruction before promotion.
2559 // This is useful to know that the high bits are sign extended bits.
2560 PromotedInsts.insert(std::pair<Instruction *, TypeIsSExt>(
2561 ExtOpnd, TypeIsSExt(ExtOpnd->getType(), IsSExt)));
2563 TPT.mutateType(ExtOpnd, Ext->getType());
2565 TPT.replaceAllUsesWith(Ext, ExtOpnd);
2567 Instruction *ExtForOpnd = Ext;
2569 DEBUG(dbgs() << "Propagate Ext to operands\n");
2570 for (int OpIdx = 0, EndOpIdx = ExtOpnd->getNumOperands(); OpIdx != EndOpIdx;
2572 DEBUG(dbgs() << "Operand:\n" << *(ExtOpnd->getOperand(OpIdx)) << '\n');
2573 if (ExtOpnd->getOperand(OpIdx)->getType() == Ext->getType() ||
2574 !shouldExtOperand(ExtOpnd, OpIdx)) {
2575 DEBUG(dbgs() << "No need to propagate\n");
2578 // Check if we can statically extend the operand.
2579 Value *Opnd = ExtOpnd->getOperand(OpIdx);
2580 if (const ConstantInt *Cst = dyn_cast<ConstantInt>(Opnd)) {
2581 DEBUG(dbgs() << "Statically extend\n");
2582 unsigned BitWidth = Ext->getType()->getIntegerBitWidth();
2583 APInt CstVal = IsSExt ? Cst->getValue().sext(BitWidth)
2584 : Cst->getValue().zext(BitWidth);
2585 TPT.setOperand(ExtOpnd, OpIdx, ConstantInt::get(Ext->getType(), CstVal));
2588 // UndefValue are typed, so we have to statically sign extend them.
2589 if (isa<UndefValue>(Opnd)) {
2590 DEBUG(dbgs() << "Statically extend\n");
2591 TPT.setOperand(ExtOpnd, OpIdx, UndefValue::get(Ext->getType()));
2595 // Otherwise we have to explicity sign extend the operand.
2596 // Check if Ext was reused to extend an operand.
2598 // If yes, create a new one.
2599 DEBUG(dbgs() << "More operands to ext\n");
2600 Value *ValForExtOpnd = IsSExt ? TPT.createSExt(Ext, Opnd, Ext->getType())
2601 : TPT.createZExt(Ext, Opnd, Ext->getType());
2602 if (!isa<Instruction>(ValForExtOpnd)) {
2603 TPT.setOperand(ExtOpnd, OpIdx, ValForExtOpnd);
2606 ExtForOpnd = cast<Instruction>(ValForExtOpnd);
2609 Exts->push_back(ExtForOpnd);
2610 TPT.setOperand(ExtForOpnd, 0, Opnd);
2612 // Move the sign extension before the insertion point.
2613 TPT.moveBefore(ExtForOpnd, ExtOpnd);
2614 TPT.setOperand(ExtOpnd, OpIdx, ExtForOpnd);
2615 CreatedInstsCost += !TLI.isExtFree(ExtForOpnd);
2616 // If more sext are required, new instructions will have to be created.
2617 ExtForOpnd = nullptr;
2619 if (ExtForOpnd == Ext) {
2620 DEBUG(dbgs() << "Extension is useless now\n");
2621 TPT.eraseInstruction(Ext);
2626 /// Check whether or not promoting an instruction to a wider type is profitable.
2627 /// \p NewCost gives the cost of extension instructions created by the
2629 /// \p OldCost gives the cost of extension instructions before the promotion
2630 /// plus the number of instructions that have been
2631 /// matched in the addressing mode the promotion.
2632 /// \p PromotedOperand is the value that has been promoted.
2633 /// \return True if the promotion is profitable, false otherwise.
2634 bool AddressingModeMatcher::isPromotionProfitable(
2635 unsigned NewCost, unsigned OldCost, Value *PromotedOperand) const {
2636 DEBUG(dbgs() << "OldCost: " << OldCost << "\tNewCost: " << NewCost << '\n');
2637 // The cost of the new extensions is greater than the cost of the
2638 // old extension plus what we folded.
2639 // This is not profitable.
2640 if (NewCost > OldCost)
2642 if (NewCost < OldCost)
2644 // The promotion is neutral but it may help folding the sign extension in
2645 // loads for instance.
2646 // Check that we did not create an illegal instruction.
2647 return isPromotedInstructionLegal(TLI, DL, PromotedOperand);
2650 /// Given an instruction or constant expr, see if we can fold the operation
2651 /// into the addressing mode. If so, update the addressing mode and return
2652 /// true, otherwise return false without modifying AddrMode.
2653 /// If \p MovedAway is not NULL, it contains the information of whether or
2654 /// not AddrInst has to be folded into the addressing mode on success.
2655 /// If \p MovedAway == true, \p AddrInst will not be part of the addressing
2656 /// because it has been moved away.
2657 /// Thus AddrInst must not be added in the matched instructions.
2658 /// This state can happen when AddrInst is a sext, since it may be moved away.
2659 /// Therefore, AddrInst may not be valid when MovedAway is true and it must
2660 /// not be referenced anymore.
2661 bool AddressingModeMatcher::matchOperationAddr(User *AddrInst, unsigned Opcode,
2664 // Avoid exponential behavior on extremely deep expression trees.
2665 if (Depth >= 5) return false;
2667 // By default, all matched instructions stay in place.
2672 case Instruction::PtrToInt:
2673 // PtrToInt is always a noop, as we know that the int type is pointer sized.
2674 return matchAddr(AddrInst->getOperand(0), Depth);
2675 case Instruction::IntToPtr: {
2676 auto AS = AddrInst->getType()->getPointerAddressSpace();
2677 auto PtrTy = MVT::getIntegerVT(DL.getPointerSizeInBits(AS));
2678 // This inttoptr is a no-op if the integer type is pointer sized.
2679 if (TLI.getValueType(DL, AddrInst->getOperand(0)->getType()) == PtrTy)
2680 return matchAddr(AddrInst->getOperand(0), Depth);
2683 case Instruction::BitCast:
2684 // BitCast is always a noop, and we can handle it as long as it is
2685 // int->int or pointer->pointer (we don't want int<->fp or something).
2686 if ((AddrInst->getOperand(0)->getType()->isPointerTy() ||
2687 AddrInst->getOperand(0)->getType()->isIntegerTy()) &&
2688 // Don't touch identity bitcasts. These were probably put here by LSR,
2689 // and we don't want to mess around with them. Assume it knows what it
2691 AddrInst->getOperand(0)->getType() != AddrInst->getType())
2692 return matchAddr(AddrInst->getOperand(0), Depth);
2694 case Instruction::AddrSpaceCast: {
2696 = AddrInst->getOperand(0)->getType()->getPointerAddressSpace();
2697 unsigned DestAS = AddrInst->getType()->getPointerAddressSpace();
2698 if (TLI.isNoopAddrSpaceCast(SrcAS, DestAS))
2699 return matchAddr(AddrInst->getOperand(0), Depth);
2702 case Instruction::Add: {
2703 // Check to see if we can merge in the RHS then the LHS. If so, we win.
2704 ExtAddrMode BackupAddrMode = AddrMode;
2705 unsigned OldSize = AddrModeInsts.size();
2706 // Start a transaction at this point.
2707 // The LHS may match but not the RHS.
2708 // Therefore, we need a higher level restoration point to undo partially
2709 // matched operation.
2710 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
2711 TPT.getRestorationPoint();
2713 if (matchAddr(AddrInst->getOperand(1), Depth+1) &&
2714 matchAddr(AddrInst->getOperand(0), Depth+1))
2717 // Restore the old addr mode info.
2718 AddrMode = BackupAddrMode;
2719 AddrModeInsts.resize(OldSize);
2720 TPT.rollback(LastKnownGood);
2722 // Otherwise this was over-aggressive. Try merging in the LHS then the RHS.
2723 if (matchAddr(AddrInst->getOperand(0), Depth+1) &&
2724 matchAddr(AddrInst->getOperand(1), Depth+1))
2727 // Otherwise we definitely can't merge the ADD in.
2728 AddrMode = BackupAddrMode;
2729 AddrModeInsts.resize(OldSize);
2730 TPT.rollback(LastKnownGood);
2733 //case Instruction::Or:
2734 // TODO: We can handle "Or Val, Imm" iff this OR is equivalent to an ADD.
2736 case Instruction::Mul:
2737 case Instruction::Shl: {
2738 // Can only handle X*C and X << C.
2739 ConstantInt *RHS = dyn_cast<ConstantInt>(AddrInst->getOperand(1));
2742 int64_t Scale = RHS->getSExtValue();
2743 if (Opcode == Instruction::Shl)
2744 Scale = 1LL << Scale;
2746 return matchScaledValue(AddrInst->getOperand(0), Scale, Depth);
2748 case Instruction::GetElementPtr: {
2749 // Scan the GEP. We check it if it contains constant offsets and at most
2750 // one variable offset.
2751 int VariableOperand = -1;
2752 unsigned VariableScale = 0;
2754 int64_t ConstantOffset = 0;
2755 gep_type_iterator GTI = gep_type_begin(AddrInst);
2756 for (unsigned i = 1, e = AddrInst->getNumOperands(); i != e; ++i, ++GTI) {
2757 if (StructType *STy = dyn_cast<StructType>(*GTI)) {
2758 const StructLayout *SL = DL.getStructLayout(STy);
2760 cast<ConstantInt>(AddrInst->getOperand(i))->getZExtValue();
2761 ConstantOffset += SL->getElementOffset(Idx);
2763 uint64_t TypeSize = DL.getTypeAllocSize(GTI.getIndexedType());
2764 if (ConstantInt *CI = dyn_cast<ConstantInt>(AddrInst->getOperand(i))) {
2765 ConstantOffset += CI->getSExtValue()*TypeSize;
2766 } else if (TypeSize) { // Scales of zero don't do anything.
2767 // We only allow one variable index at the moment.
2768 if (VariableOperand != -1)
2771 // Remember the variable index.
2772 VariableOperand = i;
2773 VariableScale = TypeSize;
2778 // A common case is for the GEP to only do a constant offset. In this case,
2779 // just add it to the disp field and check validity.
2780 if (VariableOperand == -1) {
2781 AddrMode.BaseOffs += ConstantOffset;
2782 if (ConstantOffset == 0 ||
2783 TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace)) {
2784 // Check to see if we can fold the base pointer in too.
2785 if (matchAddr(AddrInst->getOperand(0), Depth+1))
2788 AddrMode.BaseOffs -= ConstantOffset;
2792 // Save the valid addressing mode in case we can't match.
2793 ExtAddrMode BackupAddrMode = AddrMode;
2794 unsigned OldSize = AddrModeInsts.size();
2796 // See if the scale and offset amount is valid for this target.
2797 AddrMode.BaseOffs += ConstantOffset;
2799 // Match the base operand of the GEP.
2800 if (!matchAddr(AddrInst->getOperand(0), Depth+1)) {
2801 // If it couldn't be matched, just stuff the value in a register.
2802 if (AddrMode.HasBaseReg) {
2803 AddrMode = BackupAddrMode;
2804 AddrModeInsts.resize(OldSize);
2807 AddrMode.HasBaseReg = true;
2808 AddrMode.BaseReg = AddrInst->getOperand(0);
2811 // Match the remaining variable portion of the GEP.
2812 if (!matchScaledValue(AddrInst->getOperand(VariableOperand), VariableScale,
2814 // If it couldn't be matched, try stuffing the base into a register
2815 // instead of matching it, and retrying the match of the scale.
2816 AddrMode = BackupAddrMode;
2817 AddrModeInsts.resize(OldSize);
2818 if (AddrMode.HasBaseReg)
2820 AddrMode.HasBaseReg = true;
2821 AddrMode.BaseReg = AddrInst->getOperand(0);
2822 AddrMode.BaseOffs += ConstantOffset;
2823 if (!matchScaledValue(AddrInst->getOperand(VariableOperand),
2824 VariableScale, Depth)) {
2825 // If even that didn't work, bail.
2826 AddrMode = BackupAddrMode;
2827 AddrModeInsts.resize(OldSize);
2834 case Instruction::SExt:
2835 case Instruction::ZExt: {
2836 Instruction *Ext = dyn_cast<Instruction>(AddrInst);
2840 // Try to move this ext out of the way of the addressing mode.
2841 // Ask for a method for doing so.
2842 TypePromotionHelper::Action TPH =
2843 TypePromotionHelper::getAction(Ext, InsertedInsts, TLI, PromotedInsts);
2847 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
2848 TPT.getRestorationPoint();
2849 unsigned CreatedInstsCost = 0;
2850 unsigned ExtCost = !TLI.isExtFree(Ext);
2851 Value *PromotedOperand =
2852 TPH(Ext, TPT, PromotedInsts, CreatedInstsCost, nullptr, nullptr, TLI);
2853 // SExt has been moved away.
2854 // Thus either it will be rematched later in the recursive calls or it is
2855 // gone. Anyway, we must not fold it into the addressing mode at this point.
2859 // addr = gep base, idx
2861 // promotedOpnd = ext opnd <- no match here
2862 // op = promoted_add promotedOpnd, 1 <- match (later in recursive calls)
2863 // addr = gep base, op <- match
2867 assert(PromotedOperand &&
2868 "TypePromotionHelper should have filtered out those cases");
2870 ExtAddrMode BackupAddrMode = AddrMode;
2871 unsigned OldSize = AddrModeInsts.size();
2873 if (!matchAddr(PromotedOperand, Depth) ||
2874 // The total of the new cost is equal to the cost of the created
2876 // The total of the old cost is equal to the cost of the extension plus
2877 // what we have saved in the addressing mode.
2878 !isPromotionProfitable(CreatedInstsCost,
2879 ExtCost + (AddrModeInsts.size() - OldSize),
2881 AddrMode = BackupAddrMode;
2882 AddrModeInsts.resize(OldSize);
2883 DEBUG(dbgs() << "Sign extension does not pay off: rollback\n");
2884 TPT.rollback(LastKnownGood);
2893 /// If we can, try to add the value of 'Addr' into the current addressing mode.
2894 /// If Addr can't be added to AddrMode this returns false and leaves AddrMode
2895 /// unmodified. This assumes that Addr is either a pointer type or intptr_t
2898 bool AddressingModeMatcher::matchAddr(Value *Addr, unsigned Depth) {
2899 // Start a transaction at this point that we will rollback if the matching
2901 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
2902 TPT.getRestorationPoint();
2903 if (ConstantInt *CI = dyn_cast<ConstantInt>(Addr)) {
2904 // Fold in immediates if legal for the target.
2905 AddrMode.BaseOffs += CI->getSExtValue();
2906 if (TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace))
2908 AddrMode.BaseOffs -= CI->getSExtValue();
2909 } else if (GlobalValue *GV = dyn_cast<GlobalValue>(Addr)) {
2910 // If this is a global variable, try to fold it into the addressing mode.
2911 if (!AddrMode.BaseGV) {
2912 AddrMode.BaseGV = GV;
2913 if (TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace))
2915 AddrMode.BaseGV = nullptr;
2917 } else if (Instruction *I = dyn_cast<Instruction>(Addr)) {
2918 ExtAddrMode BackupAddrMode = AddrMode;
2919 unsigned OldSize = AddrModeInsts.size();
2921 // Check to see if it is possible to fold this operation.
2922 bool MovedAway = false;
2923 if (matchOperationAddr(I, I->getOpcode(), Depth, &MovedAway)) {
2924 // This instruction may have been moved away. If so, there is nothing
2928 // Okay, it's possible to fold this. Check to see if it is actually
2929 // *profitable* to do so. We use a simple cost model to avoid increasing
2930 // register pressure too much.
2931 if (I->hasOneUse() ||
2932 isProfitableToFoldIntoAddressingMode(I, BackupAddrMode, AddrMode)) {
2933 AddrModeInsts.push_back(I);
2937 // It isn't profitable to do this, roll back.
2938 //cerr << "NOT FOLDING: " << *I;
2939 AddrMode = BackupAddrMode;
2940 AddrModeInsts.resize(OldSize);
2941 TPT.rollback(LastKnownGood);
2943 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Addr)) {
2944 if (matchOperationAddr(CE, CE->getOpcode(), Depth))
2946 TPT.rollback(LastKnownGood);
2947 } else if (isa<ConstantPointerNull>(Addr)) {
2948 // Null pointer gets folded without affecting the addressing mode.
2952 // Worse case, the target should support [reg] addressing modes. :)
2953 if (!AddrMode.HasBaseReg) {
2954 AddrMode.HasBaseReg = true;
2955 AddrMode.BaseReg = Addr;
2956 // Still check for legality in case the target supports [imm] but not [i+r].
2957 if (TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace))
2959 AddrMode.HasBaseReg = false;
2960 AddrMode.BaseReg = nullptr;
2963 // If the base register is already taken, see if we can do [r+r].
2964 if (AddrMode.Scale == 0) {
2966 AddrMode.ScaledReg = Addr;
2967 if (TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace))
2970 AddrMode.ScaledReg = nullptr;
2973 TPT.rollback(LastKnownGood);
2977 /// Check to see if all uses of OpVal by the specified inline asm call are due
2978 /// to memory operands. If so, return true, otherwise return false.
2979 static bool IsOperandAMemoryOperand(CallInst *CI, InlineAsm *IA, Value *OpVal,
2980 const TargetMachine &TM) {
2981 const Function *F = CI->getParent()->getParent();
2982 const TargetLowering *TLI = TM.getSubtargetImpl(*F)->getTargetLowering();
2983 const TargetRegisterInfo *TRI = TM.getSubtargetImpl(*F)->getRegisterInfo();
2984 TargetLowering::AsmOperandInfoVector TargetConstraints =
2985 TLI->ParseConstraints(F->getParent()->getDataLayout(), TRI,
2986 ImmutableCallSite(CI));
2987 for (unsigned i = 0, e = TargetConstraints.size(); i != e; ++i) {
2988 TargetLowering::AsmOperandInfo &OpInfo = TargetConstraints[i];
2990 // Compute the constraint code and ConstraintType to use.
2991 TLI->ComputeConstraintToUse(OpInfo, SDValue());
2993 // If this asm operand is our Value*, and if it isn't an indirect memory
2994 // operand, we can't fold it!
2995 if (OpInfo.CallOperandVal == OpVal &&
2996 (OpInfo.ConstraintType != TargetLowering::C_Memory ||
2997 !OpInfo.isIndirect))
3004 /// Recursively walk all the uses of I until we find a memory use.
3005 /// If we find an obviously non-foldable instruction, return true.
3006 /// Add the ultimately found memory instructions to MemoryUses.
3007 static bool FindAllMemoryUses(
3009 SmallVectorImpl<std::pair<Instruction *, unsigned>> &MemoryUses,
3010 SmallPtrSetImpl<Instruction *> &ConsideredInsts, const TargetMachine &TM) {
3011 // If we already considered this instruction, we're done.
3012 if (!ConsideredInsts.insert(I).second)
3015 // If this is an obviously unfoldable instruction, bail out.
3016 if (!MightBeFoldableInst(I))
3019 // Loop over all the uses, recursively processing them.
3020 for (Use &U : I->uses()) {
3021 Instruction *UserI = cast<Instruction>(U.getUser());
3023 if (LoadInst *LI = dyn_cast<LoadInst>(UserI)) {
3024 MemoryUses.push_back(std::make_pair(LI, U.getOperandNo()));
3028 if (StoreInst *SI = dyn_cast<StoreInst>(UserI)) {
3029 unsigned opNo = U.getOperandNo();
3030 if (opNo == 0) return true; // Storing addr, not into addr.
3031 MemoryUses.push_back(std::make_pair(SI, opNo));
3035 if (CallInst *CI = dyn_cast<CallInst>(UserI)) {
3036 InlineAsm *IA = dyn_cast<InlineAsm>(CI->getCalledValue());
3037 if (!IA) return true;
3039 // If this is a memory operand, we're cool, otherwise bail out.
3040 if (!IsOperandAMemoryOperand(CI, IA, I, TM))
3045 if (FindAllMemoryUses(UserI, MemoryUses, ConsideredInsts, TM))
3052 /// Return true if Val is already known to be live at the use site that we're
3053 /// folding it into. If so, there is no cost to include it in the addressing
3054 /// mode. KnownLive1 and KnownLive2 are two values that we know are live at the
3055 /// instruction already.
3056 bool AddressingModeMatcher::valueAlreadyLiveAtInst(Value *Val,Value *KnownLive1,
3057 Value *KnownLive2) {
3058 // If Val is either of the known-live values, we know it is live!
3059 if (Val == nullptr || Val == KnownLive1 || Val == KnownLive2)
3062 // All values other than instructions and arguments (e.g. constants) are live.
3063 if (!isa<Instruction>(Val) && !isa<Argument>(Val)) return true;
3065 // If Val is a constant sized alloca in the entry block, it is live, this is
3066 // true because it is just a reference to the stack/frame pointer, which is
3067 // live for the whole function.
3068 if (AllocaInst *AI = dyn_cast<AllocaInst>(Val))
3069 if (AI->isStaticAlloca())
3072 // Check to see if this value is already used in the memory instruction's
3073 // block. If so, it's already live into the block at the very least, so we
3074 // can reasonably fold it.
3075 return Val->isUsedInBasicBlock(MemoryInst->getParent());
3078 /// It is possible for the addressing mode of the machine to fold the specified
3079 /// instruction into a load or store that ultimately uses it.
3080 /// However, the specified instruction has multiple uses.
3081 /// Given this, it may actually increase register pressure to fold it
3082 /// into the load. For example, consider this code:
3086 /// use(Y) -> nonload/store
3090 /// In this case, Y has multiple uses, and can be folded into the load of Z
3091 /// (yielding load [X+2]). However, doing this will cause both "X" and "X+1" to
3092 /// be live at the use(Y) line. If we don't fold Y into load Z, we use one
3093 /// fewer register. Since Y can't be folded into "use(Y)" we don't increase the
3094 /// number of computations either.
3096 /// Note that this (like most of CodeGenPrepare) is just a rough heuristic. If
3097 /// X was live across 'load Z' for other reasons, we actually *would* want to
3098 /// fold the addressing mode in the Z case. This would make Y die earlier.
3099 bool AddressingModeMatcher::
3100 isProfitableToFoldIntoAddressingMode(Instruction *I, ExtAddrMode &AMBefore,
3101 ExtAddrMode &AMAfter) {
3102 if (IgnoreProfitability) return true;
3104 // AMBefore is the addressing mode before this instruction was folded into it,
3105 // and AMAfter is the addressing mode after the instruction was folded. Get
3106 // the set of registers referenced by AMAfter and subtract out those
3107 // referenced by AMBefore: this is the set of values which folding in this
3108 // address extends the lifetime of.
3110 // Note that there are only two potential values being referenced here,
3111 // BaseReg and ScaleReg (global addresses are always available, as are any
3112 // folded immediates).
3113 Value *BaseReg = AMAfter.BaseReg, *ScaledReg = AMAfter.ScaledReg;
3115 // If the BaseReg or ScaledReg was referenced by the previous addrmode, their
3116 // lifetime wasn't extended by adding this instruction.
3117 if (valueAlreadyLiveAtInst(BaseReg, AMBefore.BaseReg, AMBefore.ScaledReg))
3119 if (valueAlreadyLiveAtInst(ScaledReg, AMBefore.BaseReg, AMBefore.ScaledReg))
3120 ScaledReg = nullptr;
3122 // If folding this instruction (and it's subexprs) didn't extend any live
3123 // ranges, we're ok with it.
3124 if (!BaseReg && !ScaledReg)
3127 // If all uses of this instruction are ultimately load/store/inlineasm's,
3128 // check to see if their addressing modes will include this instruction. If
3129 // so, we can fold it into all uses, so it doesn't matter if it has multiple
3131 SmallVector<std::pair<Instruction*,unsigned>, 16> MemoryUses;
3132 SmallPtrSet<Instruction*, 16> ConsideredInsts;
3133 if (FindAllMemoryUses(I, MemoryUses, ConsideredInsts, TM))
3134 return false; // Has a non-memory, non-foldable use!
3136 // Now that we know that all uses of this instruction are part of a chain of
3137 // computation involving only operations that could theoretically be folded
3138 // into a memory use, loop over each of these uses and see if they could
3139 // *actually* fold the instruction.
3140 SmallVector<Instruction*, 32> MatchedAddrModeInsts;
3141 for (unsigned i = 0, e = MemoryUses.size(); i != e; ++i) {
3142 Instruction *User = MemoryUses[i].first;
3143 unsigned OpNo = MemoryUses[i].second;
3145 // Get the access type of this use. If the use isn't a pointer, we don't
3146 // know what it accesses.
3147 Value *Address = User->getOperand(OpNo);
3148 PointerType *AddrTy = dyn_cast<PointerType>(Address->getType());
3151 Type *AddressAccessTy = AddrTy->getElementType();
3152 unsigned AS = AddrTy->getAddressSpace();
3154 // Do a match against the root of this address, ignoring profitability. This
3155 // will tell us if the addressing mode for the memory operation will
3156 // *actually* cover the shared instruction.
3158 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
3159 TPT.getRestorationPoint();
3160 AddressingModeMatcher Matcher(MatchedAddrModeInsts, TM, AddressAccessTy, AS,
3161 MemoryInst, Result, InsertedInsts,
3162 PromotedInsts, TPT);
3163 Matcher.IgnoreProfitability = true;
3164 bool Success = Matcher.matchAddr(Address, 0);
3165 (void)Success; assert(Success && "Couldn't select *anything*?");
3167 // The match was to check the profitability, the changes made are not
3168 // part of the original matcher. Therefore, they should be dropped
3169 // otherwise the original matcher will not present the right state.
3170 TPT.rollback(LastKnownGood);
3172 // If the match didn't cover I, then it won't be shared by it.
3173 if (std::find(MatchedAddrModeInsts.begin(), MatchedAddrModeInsts.end(),
3174 I) == MatchedAddrModeInsts.end())
3177 MatchedAddrModeInsts.clear();
3183 } // end anonymous namespace
3185 /// Return true if the specified values are defined in a
3186 /// different basic block than BB.
3187 static bool IsNonLocalValue(Value *V, BasicBlock *BB) {
3188 if (Instruction *I = dyn_cast<Instruction>(V))
3189 return I->getParent() != BB;
3193 /// Load and Store Instructions often have addressing modes that can do
3194 /// significant amounts of computation. As such, instruction selection will try
3195 /// to get the load or store to do as much computation as possible for the
3196 /// program. The problem is that isel can only see within a single block. As
3197 /// such, we sink as much legal addressing mode work into the block as possible.
3199 /// This method is used to optimize both load/store and inline asms with memory
3201 bool CodeGenPrepare::optimizeMemoryInst(Instruction *MemoryInst, Value *Addr,
3202 Type *AccessTy, unsigned AddrSpace) {
3205 // Try to collapse single-value PHI nodes. This is necessary to undo
3206 // unprofitable PRE transformations.
3207 SmallVector<Value*, 8> worklist;
3208 SmallPtrSet<Value*, 16> Visited;
3209 worklist.push_back(Addr);
3211 // Use a worklist to iteratively look through PHI nodes, and ensure that
3212 // the addressing mode obtained from the non-PHI roots of the graph
3214 Value *Consensus = nullptr;
3215 unsigned NumUsesConsensus = 0;
3216 bool IsNumUsesConsensusValid = false;
3217 SmallVector<Instruction*, 16> AddrModeInsts;
3218 ExtAddrMode AddrMode;
3219 TypePromotionTransaction TPT;
3220 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
3221 TPT.getRestorationPoint();
3222 while (!worklist.empty()) {
3223 Value *V = worklist.back();
3224 worklist.pop_back();
3226 // Break use-def graph loops.
3227 if (!Visited.insert(V).second) {
3228 Consensus = nullptr;
3232 // For a PHI node, push all of its incoming values.
3233 if (PHINode *P = dyn_cast<PHINode>(V)) {
3234 for (Value *IncValue : P->incoming_values())
3235 worklist.push_back(IncValue);
3239 // For non-PHIs, determine the addressing mode being computed.
3240 SmallVector<Instruction*, 16> NewAddrModeInsts;
3241 ExtAddrMode NewAddrMode = AddressingModeMatcher::Match(
3242 V, AccessTy, AddrSpace, MemoryInst, NewAddrModeInsts, *TM,
3243 InsertedInsts, PromotedInsts, TPT);
3245 // This check is broken into two cases with very similar code to avoid using
3246 // getNumUses() as much as possible. Some values have a lot of uses, so
3247 // calling getNumUses() unconditionally caused a significant compile-time
3251 AddrMode = NewAddrMode;
3252 AddrModeInsts = NewAddrModeInsts;
3254 } else if (NewAddrMode == AddrMode) {
3255 if (!IsNumUsesConsensusValid) {
3256 NumUsesConsensus = Consensus->getNumUses();
3257 IsNumUsesConsensusValid = true;
3260 // Ensure that the obtained addressing mode is equivalent to that obtained
3261 // for all other roots of the PHI traversal. Also, when choosing one
3262 // such root as representative, select the one with the most uses in order
3263 // to keep the cost modeling heuristics in AddressingModeMatcher
3265 unsigned NumUses = V->getNumUses();
3266 if (NumUses > NumUsesConsensus) {
3268 NumUsesConsensus = NumUses;
3269 AddrModeInsts = NewAddrModeInsts;
3274 Consensus = nullptr;
3278 // If the addressing mode couldn't be determined, or if multiple different
3279 // ones were determined, bail out now.
3281 TPT.rollback(LastKnownGood);
3286 // Check to see if any of the instructions supersumed by this addr mode are
3287 // non-local to I's BB.
3288 bool AnyNonLocal = false;
3289 for (unsigned i = 0, e = AddrModeInsts.size(); i != e; ++i) {
3290 if (IsNonLocalValue(AddrModeInsts[i], MemoryInst->getParent())) {
3296 // If all the instructions matched are already in this BB, don't do anything.
3298 DEBUG(dbgs() << "CGP: Found local addrmode: " << AddrMode << "\n");
3302 // Insert this computation right after this user. Since our caller is
3303 // scanning from the top of the BB to the bottom, reuse of the expr are
3304 // guaranteed to happen later.
3305 IRBuilder<> Builder(MemoryInst);
3307 // Now that we determined the addressing expression we want to use and know
3308 // that we have to sink it into this block. Check to see if we have already
3309 // done this for some other load/store instr in this block. If so, reuse the
3311 Value *&SunkAddr = SunkAddrs[Addr];
3313 DEBUG(dbgs() << "CGP: Reusing nonlocal addrmode: " << AddrMode << " for "
3314 << *MemoryInst << "\n");
3315 if (SunkAddr->getType() != Addr->getType())
3316 SunkAddr = Builder.CreateBitCast(SunkAddr, Addr->getType());
3317 } else if (AddrSinkUsingGEPs ||
3318 (!AddrSinkUsingGEPs.getNumOccurrences() && TM &&
3319 TM->getSubtargetImpl(*MemoryInst->getParent()->getParent())
3321 // By default, we use the GEP-based method when AA is used later. This
3322 // prevents new inttoptr/ptrtoint pairs from degrading AA capabilities.
3323 DEBUG(dbgs() << "CGP: SINKING nonlocal addrmode: " << AddrMode << " for "
3324 << *MemoryInst << "\n");
3325 Type *IntPtrTy = DL->getIntPtrType(Addr->getType());
3326 Value *ResultPtr = nullptr, *ResultIndex = nullptr;
3328 // First, find the pointer.
3329 if (AddrMode.BaseReg && AddrMode.BaseReg->getType()->isPointerTy()) {
3330 ResultPtr = AddrMode.BaseReg;
3331 AddrMode.BaseReg = nullptr;
3334 if (AddrMode.Scale && AddrMode.ScaledReg->getType()->isPointerTy()) {
3335 // We can't add more than one pointer together, nor can we scale a
3336 // pointer (both of which seem meaningless).
3337 if (ResultPtr || AddrMode.Scale != 1)
3340 ResultPtr = AddrMode.ScaledReg;
3344 if (AddrMode.BaseGV) {
3348 ResultPtr = AddrMode.BaseGV;
3351 // If the real base value actually came from an inttoptr, then the matcher
3352 // will look through it and provide only the integer value. In that case,
3354 if (!ResultPtr && AddrMode.BaseReg) {
3356 Builder.CreateIntToPtr(AddrMode.BaseReg, Addr->getType(), "sunkaddr");
3357 AddrMode.BaseReg = nullptr;
3358 } else if (!ResultPtr && AddrMode.Scale == 1) {
3360 Builder.CreateIntToPtr(AddrMode.ScaledReg, Addr->getType(), "sunkaddr");
3365 !AddrMode.BaseReg && !AddrMode.Scale && !AddrMode.BaseOffs) {
3366 SunkAddr = Constant::getNullValue(Addr->getType());
3367 } else if (!ResultPtr) {
3371 Builder.getInt8PtrTy(Addr->getType()->getPointerAddressSpace());
3372 Type *I8Ty = Builder.getInt8Ty();
3374 // Start with the base register. Do this first so that subsequent address
3375 // matching finds it last, which will prevent it from trying to match it
3376 // as the scaled value in case it happens to be a mul. That would be
3377 // problematic if we've sunk a different mul for the scale, because then
3378 // we'd end up sinking both muls.
3379 if (AddrMode.BaseReg) {
3380 Value *V = AddrMode.BaseReg;
3381 if (V->getType() != IntPtrTy)
3382 V = Builder.CreateIntCast(V, IntPtrTy, /*isSigned=*/true, "sunkaddr");
3387 // Add the scale value.
3388 if (AddrMode.Scale) {
3389 Value *V = AddrMode.ScaledReg;
3390 if (V->getType() == IntPtrTy) {
3392 } else if (cast<IntegerType>(IntPtrTy)->getBitWidth() <
3393 cast<IntegerType>(V->getType())->getBitWidth()) {
3394 V = Builder.CreateTrunc(V, IntPtrTy, "sunkaddr");
3396 // It is only safe to sign extend the BaseReg if we know that the math
3397 // required to create it did not overflow before we extend it. Since
3398 // the original IR value was tossed in favor of a constant back when
3399 // the AddrMode was created we need to bail out gracefully if widths
3400 // do not match instead of extending it.
3401 Instruction *I = dyn_cast_or_null<Instruction>(ResultIndex);
3402 if (I && (ResultIndex != AddrMode.BaseReg))
3403 I->eraseFromParent();
3407 if (AddrMode.Scale != 1)
3408 V = Builder.CreateMul(V, ConstantInt::get(IntPtrTy, AddrMode.Scale),
3411 ResultIndex = Builder.CreateAdd(ResultIndex, V, "sunkaddr");
3416 // Add in the Base Offset if present.
3417 if (AddrMode.BaseOffs) {
3418 Value *V = ConstantInt::get(IntPtrTy, AddrMode.BaseOffs);
3420 // We need to add this separately from the scale above to help with
3421 // SDAG consecutive load/store merging.
3422 if (ResultPtr->getType() != I8PtrTy)
3423 ResultPtr = Builder.CreateBitCast(ResultPtr, I8PtrTy);
3424 ResultPtr = Builder.CreateGEP(I8Ty, ResultPtr, ResultIndex, "sunkaddr");
3431 SunkAddr = ResultPtr;
3433 if (ResultPtr->getType() != I8PtrTy)
3434 ResultPtr = Builder.CreateBitCast(ResultPtr, I8PtrTy);
3435 SunkAddr = Builder.CreateGEP(I8Ty, ResultPtr, ResultIndex, "sunkaddr");
3438 if (SunkAddr->getType() != Addr->getType())
3439 SunkAddr = Builder.CreateBitCast(SunkAddr, Addr->getType());
3442 DEBUG(dbgs() << "CGP: SINKING nonlocal addrmode: " << AddrMode << " for "
3443 << *MemoryInst << "\n");
3444 Type *IntPtrTy = DL->getIntPtrType(Addr->getType());
3445 Value *Result = nullptr;
3447 // Start with the base register. Do this first so that subsequent address
3448 // matching finds it last, which will prevent it from trying to match it
3449 // as the scaled value in case it happens to be a mul. That would be
3450 // problematic if we've sunk a different mul for the scale, because then
3451 // we'd end up sinking both muls.
3452 if (AddrMode.BaseReg) {
3453 Value *V = AddrMode.BaseReg;
3454 if (V->getType()->isPointerTy())
3455 V = Builder.CreatePtrToInt(V, IntPtrTy, "sunkaddr");
3456 if (V->getType() != IntPtrTy)
3457 V = Builder.CreateIntCast(V, IntPtrTy, /*isSigned=*/true, "sunkaddr");
3461 // Add the scale value.
3462 if (AddrMode.Scale) {
3463 Value *V = AddrMode.ScaledReg;
3464 if (V->getType() == IntPtrTy) {
3466 } else if (V->getType()->isPointerTy()) {
3467 V = Builder.CreatePtrToInt(V, IntPtrTy, "sunkaddr");
3468 } else if (cast<IntegerType>(IntPtrTy)->getBitWidth() <
3469 cast<IntegerType>(V->getType())->getBitWidth()) {
3470 V = Builder.CreateTrunc(V, IntPtrTy, "sunkaddr");
3472 // It is only safe to sign extend the BaseReg if we know that the math
3473 // required to create it did not overflow before we extend it. Since
3474 // the original IR value was tossed in favor of a constant back when
3475 // the AddrMode was created we need to bail out gracefully if widths
3476 // do not match instead of extending it.
3477 Instruction *I = dyn_cast_or_null<Instruction>(Result);
3478 if (I && (Result != AddrMode.BaseReg))
3479 I->eraseFromParent();
3482 if (AddrMode.Scale != 1)
3483 V = Builder.CreateMul(V, ConstantInt::get(IntPtrTy, AddrMode.Scale),
3486 Result = Builder.CreateAdd(Result, V, "sunkaddr");
3491 // Add in the BaseGV if present.
3492 if (AddrMode.BaseGV) {
3493 Value *V = Builder.CreatePtrToInt(AddrMode.BaseGV, IntPtrTy, "sunkaddr");
3495 Result = Builder.CreateAdd(Result, V, "sunkaddr");
3500 // Add in the Base Offset if present.
3501 if (AddrMode.BaseOffs) {
3502 Value *V = ConstantInt::get(IntPtrTy, AddrMode.BaseOffs);
3504 Result = Builder.CreateAdd(Result, V, "sunkaddr");
3510 SunkAddr = Constant::getNullValue(Addr->getType());
3512 SunkAddr = Builder.CreateIntToPtr(Result, Addr->getType(), "sunkaddr");
3515 MemoryInst->replaceUsesOfWith(Repl, SunkAddr);
3517 // If we have no uses, recursively delete the value and all dead instructions
3519 if (Repl->use_empty()) {
3520 // This can cause recursive deletion, which can invalidate our iterator.
3521 // Use a WeakVH to hold onto it in case this happens.
3522 WeakVH IterHandle(CurInstIterator);
3523 BasicBlock *BB = CurInstIterator->getParent();
3525 RecursivelyDeleteTriviallyDeadInstructions(Repl, TLInfo);
3527 if (IterHandle != CurInstIterator) {
3528 // If the iterator instruction was recursively deleted, start over at the
3529 // start of the block.
3530 CurInstIterator = BB->begin();
3538 /// If there are any memory operands, use OptimizeMemoryInst to sink their
3539 /// address computing into the block when possible / profitable.
3540 bool CodeGenPrepare::optimizeInlineAsmInst(CallInst *CS) {
3541 bool MadeChange = false;
3543 const TargetRegisterInfo *TRI =
3544 TM->getSubtargetImpl(*CS->getParent()->getParent())->getRegisterInfo();
3545 TargetLowering::AsmOperandInfoVector TargetConstraints =
3546 TLI->ParseConstraints(*DL, TRI, CS);
3548 for (unsigned i = 0, e = TargetConstraints.size(); i != e; ++i) {
3549 TargetLowering::AsmOperandInfo &OpInfo = TargetConstraints[i];
3551 // Compute the constraint code and ConstraintType to use.
3552 TLI->ComputeConstraintToUse(OpInfo, SDValue());
3554 if (OpInfo.ConstraintType == TargetLowering::C_Memory &&
3555 OpInfo.isIndirect) {
3556 Value *OpVal = CS->getArgOperand(ArgNo++);
3557 MadeChange |= optimizeMemoryInst(CS, OpVal, OpVal->getType(), ~0u);
3558 } else if (OpInfo.Type == InlineAsm::isInput)
3565 /// \brief Check if all the uses of \p Inst are equivalent (or free) zero or
3566 /// sign extensions.
3567 static bool hasSameExtUse(Instruction *Inst, const TargetLowering &TLI) {
3568 assert(!Inst->use_empty() && "Input must have at least one use");
3569 const Instruction *FirstUser = cast<Instruction>(*Inst->user_begin());
3570 bool IsSExt = isa<SExtInst>(FirstUser);
3571 Type *ExtTy = FirstUser->getType();
3572 for (const User *U : Inst->users()) {
3573 const Instruction *UI = cast<Instruction>(U);
3574 if ((IsSExt && !isa<SExtInst>(UI)) || (!IsSExt && !isa<ZExtInst>(UI)))
3576 Type *CurTy = UI->getType();
3577 // Same input and output types: Same instruction after CSE.
3581 // If IsSExt is true, we are in this situation:
3583 // b = sext ty1 a to ty2
3584 // c = sext ty1 a to ty3
3585 // Assuming ty2 is shorter than ty3, this could be turned into:
3587 // b = sext ty1 a to ty2
3588 // c = sext ty2 b to ty3
3589 // However, the last sext is not free.
3593 // This is a ZExt, maybe this is free to extend from one type to another.
3594 // In that case, we would not account for a different use.
3597 if (ExtTy->getScalarType()->getIntegerBitWidth() >
3598 CurTy->getScalarType()->getIntegerBitWidth()) {
3606 if (!TLI.isZExtFree(NarrowTy, LargeTy))
3609 // All uses are the same or can be derived from one another for free.
3613 /// \brief Try to form ExtLd by promoting \p Exts until they reach a
3614 /// load instruction.
3615 /// If an ext(load) can be formed, it is returned via \p LI for the load
3616 /// and \p Inst for the extension.
3617 /// Otherwise LI == nullptr and Inst == nullptr.
3618 /// When some promotion happened, \p TPT contains the proper state to
3621 /// \return true when promoting was necessary to expose the ext(load)
3622 /// opportunity, false otherwise.
3626 /// %ld = load i32* %addr
3627 /// %add = add nuw i32 %ld, 4
3628 /// %zext = zext i32 %add to i64
3632 /// %ld = load i32* %addr
3633 /// %zext = zext i32 %ld to i64
3634 /// %add = add nuw i64 %zext, 4
3636 /// Thanks to the promotion, we can match zext(load i32*) to i64.
3637 bool CodeGenPrepare::extLdPromotion(TypePromotionTransaction &TPT,
3638 LoadInst *&LI, Instruction *&Inst,
3639 const SmallVectorImpl<Instruction *> &Exts,
3640 unsigned CreatedInstsCost = 0) {
3641 // Iterate over all the extensions to see if one form an ext(load).
3642 for (auto I : Exts) {
3643 // Check if we directly have ext(load).
3644 if ((LI = dyn_cast<LoadInst>(I->getOperand(0)))) {
3646 // No promotion happened here.
3649 // Check whether or not we want to do any promotion.
3650 if (!TLI || !TLI->enableExtLdPromotion() || DisableExtLdPromotion)
3652 // Get the action to perform the promotion.
3653 TypePromotionHelper::Action TPH = TypePromotionHelper::getAction(
3654 I, InsertedInsts, *TLI, PromotedInsts);
3655 // Check if we can promote.
3658 // Save the current state.
3659 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
3660 TPT.getRestorationPoint();
3661 SmallVector<Instruction *, 4> NewExts;
3662 unsigned NewCreatedInstsCost = 0;
3663 unsigned ExtCost = !TLI->isExtFree(I);
3665 Value *PromotedVal = TPH(I, TPT, PromotedInsts, NewCreatedInstsCost,
3666 &NewExts, nullptr, *TLI);
3667 assert(PromotedVal &&
3668 "TypePromotionHelper should have filtered out those cases");
3670 // We would be able to merge only one extension in a load.
3671 // Therefore, if we have more than 1 new extension we heuristically
3672 // cut this search path, because it means we degrade the code quality.
3673 // With exactly 2, the transformation is neutral, because we will merge
3674 // one extension but leave one. However, we optimistically keep going,
3675 // because the new extension may be removed too.
3676 long long TotalCreatedInstsCost = CreatedInstsCost + NewCreatedInstsCost;
3677 TotalCreatedInstsCost -= ExtCost;
3678 if (!StressExtLdPromotion &&
3679 (TotalCreatedInstsCost > 1 ||
3680 !isPromotedInstructionLegal(*TLI, *DL, PromotedVal))) {
3681 // The promotion is not profitable, rollback to the previous state.
3682 TPT.rollback(LastKnownGood);
3685 // The promotion is profitable.
3686 // Check if it exposes an ext(load).
3687 (void)extLdPromotion(TPT, LI, Inst, NewExts, TotalCreatedInstsCost);
3688 if (LI && (StressExtLdPromotion || NewCreatedInstsCost <= ExtCost ||
3689 // If we have created a new extension, i.e., now we have two
3690 // extensions. We must make sure one of them is merged with
3691 // the load, otherwise we may degrade the code quality.
3692 (LI->hasOneUse() || hasSameExtUse(LI, *TLI))))
3693 // Promotion happened.
3695 // If this does not help to expose an ext(load) then, rollback.
3696 TPT.rollback(LastKnownGood);
3698 // None of the extension can form an ext(load).
3704 /// Move a zext or sext fed by a load into the same basic block as the load,
3705 /// unless conditions are unfavorable. This allows SelectionDAG to fold the
3706 /// extend into the load.
3707 /// \p I[in/out] the extension may be modified during the process if some
3708 /// promotions apply.
3710 bool CodeGenPrepare::moveExtToFormExtLoad(Instruction *&I) {
3711 // Try to promote a chain of computation if it allows to form
3712 // an extended load.
3713 TypePromotionTransaction TPT;
3714 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
3715 TPT.getRestorationPoint();
3716 SmallVector<Instruction *, 1> Exts;
3718 // Look for a load being extended.
3719 LoadInst *LI = nullptr;
3720 Instruction *OldExt = I;
3721 bool HasPromoted = extLdPromotion(TPT, LI, I, Exts);
3723 assert(!HasPromoted && !LI && "If we did not match any load instruction "
3724 "the code must remain the same");
3729 // If they're already in the same block, there's nothing to do.
3730 // Make the cheap checks first if we did not promote.
3731 // If we promoted, we need to check if it is indeed profitable.
3732 if (!HasPromoted && LI->getParent() == I->getParent())
3735 EVT VT = TLI->getValueType(*DL, I->getType());
3736 EVT LoadVT = TLI->getValueType(*DL, LI->getType());
3738 // If the load has other users and the truncate is not free, this probably
3739 // isn't worthwhile.
3740 if (!LI->hasOneUse() && TLI &&
3741 (TLI->isTypeLegal(LoadVT) || !TLI->isTypeLegal(VT)) &&
3742 !TLI->isTruncateFree(I->getType(), LI->getType())) {
3744 TPT.rollback(LastKnownGood);
3748 // Check whether the target supports casts folded into loads.
3750 if (isa<ZExtInst>(I))
3751 LType = ISD::ZEXTLOAD;
3753 assert(isa<SExtInst>(I) && "Unexpected ext type!");
3754 LType = ISD::SEXTLOAD;
3756 if (TLI && !TLI->isLoadExtLegal(LType, VT, LoadVT)) {
3758 TPT.rollback(LastKnownGood);
3762 // Move the extend into the same block as the load, so that SelectionDAG
3765 I->removeFromParent();
3771 bool CodeGenPrepare::optimizeExtUses(Instruction *I) {
3772 BasicBlock *DefBB = I->getParent();
3774 // If the result of a {s|z}ext and its source are both live out, rewrite all
3775 // other uses of the source with result of extension.
3776 Value *Src = I->getOperand(0);
3777 if (Src->hasOneUse())
3780 // Only do this xform if truncating is free.
3781 if (TLI && !TLI->isTruncateFree(I->getType(), Src->getType()))
3784 // Only safe to perform the optimization if the source is also defined in
3786 if (!isa<Instruction>(Src) || DefBB != cast<Instruction>(Src)->getParent())
3789 bool DefIsLiveOut = false;
3790 for (User *U : I->users()) {
3791 Instruction *UI = cast<Instruction>(U);
3793 // Figure out which BB this ext is used in.
3794 BasicBlock *UserBB = UI->getParent();
3795 if (UserBB == DefBB) continue;
3796 DefIsLiveOut = true;
3802 // Make sure none of the uses are PHI nodes.
3803 for (User *U : Src->users()) {
3804 Instruction *UI = cast<Instruction>(U);
3805 BasicBlock *UserBB = UI->getParent();
3806 if (UserBB == DefBB) continue;
3807 // Be conservative. We don't want this xform to end up introducing
3808 // reloads just before load / store instructions.
3809 if (isa<PHINode>(UI) || isa<LoadInst>(UI) || isa<StoreInst>(UI))
3813 // InsertedTruncs - Only insert one trunc in each block once.
3814 DenseMap<BasicBlock*, Instruction*> InsertedTruncs;
3816 bool MadeChange = false;
3817 for (Use &U : Src->uses()) {
3818 Instruction *User = cast<Instruction>(U.getUser());
3820 // Figure out which BB this ext is used in.
3821 BasicBlock *UserBB = User->getParent();
3822 if (UserBB == DefBB) continue;
3824 // Both src and def are live in this block. Rewrite the use.
3825 Instruction *&InsertedTrunc = InsertedTruncs[UserBB];
3827 if (!InsertedTrunc) {
3828 BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
3829 InsertedTrunc = new TruncInst(I, Src->getType(), "", InsertPt);
3830 InsertedInsts.insert(InsertedTrunc);
3833 // Replace a use of the {s|z}ext source with a use of the result.
3842 /// Returns true if a SelectInst should be turned into an explicit branch.
3843 static bool isFormingBranchFromSelectProfitable(SelectInst *SI) {
3844 // FIXME: This should use the same heuristics as IfConversion to determine
3845 // whether a select is better represented as a branch. This requires that
3846 // branch probability metadata is preserved for the select, which is not the
3849 CmpInst *Cmp = dyn_cast<CmpInst>(SI->getCondition());
3851 // If a branch is predictable, an out-of-order CPU can avoid blocking on its
3852 // comparison condition. If the compare has more than one use, there's
3853 // probably another cmov or setcc around, so it's not worth emitting a branch.
3854 if (!Cmp || !Cmp->hasOneUse())
3857 Value *CmpOp0 = Cmp->getOperand(0);
3858 Value *CmpOp1 = Cmp->getOperand(1);
3860 // Emit "cmov on compare with a memory operand" as a branch to avoid stalls
3861 // on a load from memory. But if the load is used more than once, do not
3862 // change the select to a branch because the load is probably needed
3863 // regardless of whether the branch is taken or not.
3864 return ((isa<LoadInst>(CmpOp0) && CmpOp0->hasOneUse()) ||
3865 (isa<LoadInst>(CmpOp1) && CmpOp1->hasOneUse()));
3869 /// If we have a SelectInst that will likely profit from branch prediction,
3870 /// turn it into a branch.
3871 bool CodeGenPrepare::optimizeSelectInst(SelectInst *SI) {
3872 bool VectorCond = !SI->getCondition()->getType()->isIntegerTy(1);
3874 // Can we convert the 'select' to CF ?
3875 if (DisableSelectToBranch || OptSize || !TLI || VectorCond)
3878 TargetLowering::SelectSupportKind SelectKind;
3880 SelectKind = TargetLowering::VectorMaskSelect;
3881 else if (SI->getType()->isVectorTy())
3882 SelectKind = TargetLowering::ScalarCondVectorVal;
3884 SelectKind = TargetLowering::ScalarValSelect;
3886 // Do we have efficient codegen support for this kind of 'selects' ?
3887 if (TLI->isSelectSupported(SelectKind)) {
3888 // We have efficient codegen support for the select instruction.
3889 // Check if it is profitable to keep this 'select'.
3890 if (!TLI->isPredictableSelectExpensive() ||
3891 !isFormingBranchFromSelectProfitable(SI))
3897 // First, we split the block containing the select into 2 blocks.
3898 BasicBlock *StartBlock = SI->getParent();
3899 BasicBlock::iterator SplitPt = ++(BasicBlock::iterator(SI));
3900 BasicBlock *NextBlock = StartBlock->splitBasicBlock(SplitPt, "select.end");
3902 // Create a new block serving as the landing pad for the branch.
3903 BasicBlock *SmallBlock = BasicBlock::Create(SI->getContext(), "select.mid",
3904 NextBlock->getParent(), NextBlock);
3906 // Move the unconditional branch from the block with the select in it into our
3907 // landing pad block.
3908 StartBlock->getTerminator()->eraseFromParent();
3909 BranchInst::Create(NextBlock, SmallBlock);
3911 // Insert the real conditional branch based on the original condition.
3912 BranchInst::Create(NextBlock, SmallBlock, SI->getCondition(), SI);
3914 // The select itself is replaced with a PHI Node.
3915 PHINode *PN = PHINode::Create(SI->getType(), 2, "", NextBlock->begin());
3917 PN->addIncoming(SI->getTrueValue(), StartBlock);
3918 PN->addIncoming(SI->getFalseValue(), SmallBlock);
3919 SI->replaceAllUsesWith(PN);
3920 SI->eraseFromParent();
3922 // Instruct OptimizeBlock to skip to the next block.
3923 CurInstIterator = StartBlock->end();
3924 ++NumSelectsExpanded;
3928 static bool isBroadcastShuffle(ShuffleVectorInst *SVI) {
3929 SmallVector<int, 16> Mask(SVI->getShuffleMask());
3931 for (unsigned i = 0; i < Mask.size(); ++i) {
3932 if (SplatElem != -1 && Mask[i] != -1 && Mask[i] != SplatElem)
3934 SplatElem = Mask[i];
3940 /// Some targets have expensive vector shifts if the lanes aren't all the same
3941 /// (e.g. x86 only introduced "vpsllvd" and friends with AVX2). In these cases
3942 /// it's often worth sinking a shufflevector splat down to its use so that
3943 /// codegen can spot all lanes are identical.
3944 bool CodeGenPrepare::optimizeShuffleVectorInst(ShuffleVectorInst *SVI) {
3945 BasicBlock *DefBB = SVI->getParent();
3947 // Only do this xform if variable vector shifts are particularly expensive.
3948 if (!TLI || !TLI->isVectorShiftByScalarCheap(SVI->getType()))
3951 // We only expect better codegen by sinking a shuffle if we can recognise a
3953 if (!isBroadcastShuffle(SVI))
3956 // InsertedShuffles - Only insert a shuffle in each block once.
3957 DenseMap<BasicBlock*, Instruction*> InsertedShuffles;
3959 bool MadeChange = false;
3960 for (User *U : SVI->users()) {
3961 Instruction *UI = cast<Instruction>(U);
3963 // Figure out which BB this ext is used in.
3964 BasicBlock *UserBB = UI->getParent();
3965 if (UserBB == DefBB) continue;
3967 // For now only apply this when the splat is used by a shift instruction.
3968 if (!UI->isShift()) continue;
3970 // Everything checks out, sink the shuffle if the user's block doesn't
3971 // already have a copy.
3972 Instruction *&InsertedShuffle = InsertedShuffles[UserBB];
3974 if (!InsertedShuffle) {
3975 BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
3976 InsertedShuffle = new ShuffleVectorInst(SVI->getOperand(0),
3978 SVI->getOperand(2), "", InsertPt);
3981 UI->replaceUsesOfWith(SVI, InsertedShuffle);
3985 // If we removed all uses, nuke the shuffle.
3986 if (SVI->use_empty()) {
3987 SVI->eraseFromParent();
3995 /// \brief Helper class to promote a scalar operation to a vector one.
3996 /// This class is used to move downward extractelement transition.
3998 /// a = vector_op <2 x i32>
3999 /// b = extractelement <2 x i32> a, i32 0
4004 /// a = vector_op <2 x i32>
4005 /// c = vector_op a (equivalent to scalar_op on the related lane)
4006 /// * d = extractelement <2 x i32> c, i32 0
4008 /// Assuming both extractelement and store can be combine, we get rid of the
4010 class VectorPromoteHelper {
4011 /// DataLayout associated with the current module.
4012 const DataLayout &DL;
4014 /// Used to perform some checks on the legality of vector operations.
4015 const TargetLowering &TLI;
4017 /// Used to estimated the cost of the promoted chain.
4018 const TargetTransformInfo &TTI;
4020 /// The transition being moved downwards.
4021 Instruction *Transition;
4022 /// The sequence of instructions to be promoted.
4023 SmallVector<Instruction *, 4> InstsToBePromoted;
4024 /// Cost of combining a store and an extract.
4025 unsigned StoreExtractCombineCost;
4026 /// Instruction that will be combined with the transition.
4027 Instruction *CombineInst;
4029 /// \brief The instruction that represents the current end of the transition.
4030 /// Since we are faking the promotion until we reach the end of the chain
4031 /// of computation, we need a way to get the current end of the transition.
4032 Instruction *getEndOfTransition() const {
4033 if (InstsToBePromoted.empty())
4035 return InstsToBePromoted.back();
4038 /// \brief Return the index of the original value in the transition.
4039 /// E.g., for "extractelement <2 x i32> c, i32 1" the original value,
4040 /// c, is at index 0.
4041 unsigned getTransitionOriginalValueIdx() const {
4042 assert(isa<ExtractElementInst>(Transition) &&
4043 "Other kind of transitions are not supported yet");
4047 /// \brief Return the index of the index in the transition.
4048 /// E.g., for "extractelement <2 x i32> c, i32 0" the index
4050 unsigned getTransitionIdx() const {
4051 assert(isa<ExtractElementInst>(Transition) &&
4052 "Other kind of transitions are not supported yet");
4056 /// \brief Get the type of the transition.
4057 /// This is the type of the original value.
4058 /// E.g., for "extractelement <2 x i32> c, i32 1" the type of the
4059 /// transition is <2 x i32>.
4060 Type *getTransitionType() const {
4061 return Transition->getOperand(getTransitionOriginalValueIdx())->getType();
4064 /// \brief Promote \p ToBePromoted by moving \p Def downward through.
4065 /// I.e., we have the following sequence:
4066 /// Def = Transition <ty1> a to <ty2>
4067 /// b = ToBePromoted <ty2> Def, ...
4069 /// b = ToBePromoted <ty1> a, ...
4070 /// Def = Transition <ty1> ToBePromoted to <ty2>
4071 void promoteImpl(Instruction *ToBePromoted);
4073 /// \brief Check whether or not it is profitable to promote all the
4074 /// instructions enqueued to be promoted.
4075 bool isProfitableToPromote() {
4076 Value *ValIdx = Transition->getOperand(getTransitionOriginalValueIdx());
4077 unsigned Index = isa<ConstantInt>(ValIdx)
4078 ? cast<ConstantInt>(ValIdx)->getZExtValue()
4080 Type *PromotedType = getTransitionType();
4082 StoreInst *ST = cast<StoreInst>(CombineInst);
4083 unsigned AS = ST->getPointerAddressSpace();
4084 unsigned Align = ST->getAlignment();
4085 // Check if this store is supported.
4086 if (!TLI.allowsMisalignedMemoryAccesses(
4087 TLI.getValueType(DL, ST->getValueOperand()->getType()), AS,
4089 // If this is not supported, there is no way we can combine
4090 // the extract with the store.
4094 // The scalar chain of computation has to pay for the transition
4095 // scalar to vector.
4096 // The vector chain has to account for the combining cost.
4097 uint64_t ScalarCost =
4098 TTI.getVectorInstrCost(Transition->getOpcode(), PromotedType, Index);
4099 uint64_t VectorCost = StoreExtractCombineCost;
4100 for (const auto &Inst : InstsToBePromoted) {
4101 // Compute the cost.
4102 // By construction, all instructions being promoted are arithmetic ones.
4103 // Moreover, one argument is a constant that can be viewed as a splat
4105 Value *Arg0 = Inst->getOperand(0);
4106 bool IsArg0Constant = isa<UndefValue>(Arg0) || isa<ConstantInt>(Arg0) ||
4107 isa<ConstantFP>(Arg0);
4108 TargetTransformInfo::OperandValueKind Arg0OVK =
4109 IsArg0Constant ? TargetTransformInfo::OK_UniformConstantValue
4110 : TargetTransformInfo::OK_AnyValue;
4111 TargetTransformInfo::OperandValueKind Arg1OVK =
4112 !IsArg0Constant ? TargetTransformInfo::OK_UniformConstantValue
4113 : TargetTransformInfo::OK_AnyValue;
4114 ScalarCost += TTI.getArithmeticInstrCost(
4115 Inst->getOpcode(), Inst->getType(), Arg0OVK, Arg1OVK);
4116 VectorCost += TTI.getArithmeticInstrCost(Inst->getOpcode(), PromotedType,
4119 DEBUG(dbgs() << "Estimated cost of computation to be promoted:\nScalar: "
4120 << ScalarCost << "\nVector: " << VectorCost << '\n');
4121 return ScalarCost > VectorCost;
4124 /// \brief Generate a constant vector with \p Val with the same
4125 /// number of elements as the transition.
4126 /// \p UseSplat defines whether or not \p Val should be replicated
4127 /// across the whole vector.
4128 /// In other words, if UseSplat == true, we generate <Val, Val, ..., Val>,
4129 /// otherwise we generate a vector with as many undef as possible:
4130 /// <undef, ..., undef, Val, undef, ..., undef> where \p Val is only
4131 /// used at the index of the extract.
4132 Value *getConstantVector(Constant *Val, bool UseSplat) const {
4133 unsigned ExtractIdx = UINT_MAX;
4135 // If we cannot determine where the constant must be, we have to
4136 // use a splat constant.
4137 Value *ValExtractIdx = Transition->getOperand(getTransitionIdx());
4138 if (ConstantInt *CstVal = dyn_cast<ConstantInt>(ValExtractIdx))
4139 ExtractIdx = CstVal->getSExtValue();
4144 unsigned End = getTransitionType()->getVectorNumElements();
4146 return ConstantVector::getSplat(End, Val);
4148 SmallVector<Constant *, 4> ConstVec;
4149 UndefValue *UndefVal = UndefValue::get(Val->getType());
4150 for (unsigned Idx = 0; Idx != End; ++Idx) {
4151 if (Idx == ExtractIdx)
4152 ConstVec.push_back(Val);
4154 ConstVec.push_back(UndefVal);
4156 return ConstantVector::get(ConstVec);
4159 /// \brief Check if promoting to a vector type an operand at \p OperandIdx
4160 /// in \p Use can trigger undefined behavior.
4161 static bool canCauseUndefinedBehavior(const Instruction *Use,
4162 unsigned OperandIdx) {
4163 // This is not safe to introduce undef when the operand is on
4164 // the right hand side of a division-like instruction.
4165 if (OperandIdx != 1)
4167 switch (Use->getOpcode()) {
4170 case Instruction::SDiv:
4171 case Instruction::UDiv:
4172 case Instruction::SRem:
4173 case Instruction::URem:
4175 case Instruction::FDiv:
4176 case Instruction::FRem:
4177 return !Use->hasNoNaNs();
4179 llvm_unreachable(nullptr);
4183 VectorPromoteHelper(const DataLayout &DL, const TargetLowering &TLI,
4184 const TargetTransformInfo &TTI, Instruction *Transition,
4185 unsigned CombineCost)
4186 : DL(DL), TLI(TLI), TTI(TTI), Transition(Transition),
4187 StoreExtractCombineCost(CombineCost), CombineInst(nullptr) {
4188 assert(Transition && "Do not know how to promote null");
4191 /// \brief Check if we can promote \p ToBePromoted to \p Type.
4192 bool canPromote(const Instruction *ToBePromoted) const {
4193 // We could support CastInst too.
4194 return isa<BinaryOperator>(ToBePromoted);
4197 /// \brief Check if it is profitable to promote \p ToBePromoted
4198 /// by moving downward the transition through.
4199 bool shouldPromote(const Instruction *ToBePromoted) const {
4200 // Promote only if all the operands can be statically expanded.
4201 // Indeed, we do not want to introduce any new kind of transitions.
4202 for (const Use &U : ToBePromoted->operands()) {
4203 const Value *Val = U.get();
4204 if (Val == getEndOfTransition()) {
4205 // If the use is a division and the transition is on the rhs,
4206 // we cannot promote the operation, otherwise we may create a
4207 // division by zero.
4208 if (canCauseUndefinedBehavior(ToBePromoted, U.getOperandNo()))
4212 if (!isa<ConstantInt>(Val) && !isa<UndefValue>(Val) &&
4213 !isa<ConstantFP>(Val))
4216 // Check that the resulting operation is legal.
4217 int ISDOpcode = TLI.InstructionOpcodeToISD(ToBePromoted->getOpcode());
4220 return StressStoreExtract ||
4221 TLI.isOperationLegalOrCustom(
4222 ISDOpcode, TLI.getValueType(DL, getTransitionType(), true));
4225 /// \brief Check whether or not \p Use can be combined
4226 /// with the transition.
4227 /// I.e., is it possible to do Use(Transition) => AnotherUse?
4228 bool canCombine(const Instruction *Use) { return isa<StoreInst>(Use); }
4230 /// \brief Record \p ToBePromoted as part of the chain to be promoted.
4231 void enqueueForPromotion(Instruction *ToBePromoted) {
4232 InstsToBePromoted.push_back(ToBePromoted);
4235 /// \brief Set the instruction that will be combined with the transition.
4236 void recordCombineInstruction(Instruction *ToBeCombined) {
4237 assert(canCombine(ToBeCombined) && "Unsupported instruction to combine");
4238 CombineInst = ToBeCombined;
4241 /// \brief Promote all the instructions enqueued for promotion if it is
4243 /// \return True if the promotion happened, false otherwise.
4245 // Check if there is something to promote.
4246 // Right now, if we do not have anything to combine with,
4247 // we assume the promotion is not profitable.
4248 if (InstsToBePromoted.empty() || !CombineInst)
4252 if (!StressStoreExtract && !isProfitableToPromote())
4256 for (auto &ToBePromoted : InstsToBePromoted)
4257 promoteImpl(ToBePromoted);
4258 InstsToBePromoted.clear();
4262 } // End of anonymous namespace.
4264 void VectorPromoteHelper::promoteImpl(Instruction *ToBePromoted) {
4265 // At this point, we know that all the operands of ToBePromoted but Def
4266 // can be statically promoted.
4267 // For Def, we need to use its parameter in ToBePromoted:
4268 // b = ToBePromoted ty1 a
4269 // Def = Transition ty1 b to ty2
4270 // Move the transition down.
4271 // 1. Replace all uses of the promoted operation by the transition.
4272 // = ... b => = ... Def.
4273 assert(ToBePromoted->getType() == Transition->getType() &&
4274 "The type of the result of the transition does not match "
4276 ToBePromoted->replaceAllUsesWith(Transition);
4277 // 2. Update the type of the uses.
4278 // b = ToBePromoted ty2 Def => b = ToBePromoted ty1 Def.
4279 Type *TransitionTy = getTransitionType();
4280 ToBePromoted->mutateType(TransitionTy);
4281 // 3. Update all the operands of the promoted operation with promoted
4283 // b = ToBePromoted ty1 Def => b = ToBePromoted ty1 a.
4284 for (Use &U : ToBePromoted->operands()) {
4285 Value *Val = U.get();
4286 Value *NewVal = nullptr;
4287 if (Val == Transition)
4288 NewVal = Transition->getOperand(getTransitionOriginalValueIdx());
4289 else if (isa<UndefValue>(Val) || isa<ConstantInt>(Val) ||
4290 isa<ConstantFP>(Val)) {
4291 // Use a splat constant if it is not safe to use undef.
4292 NewVal = getConstantVector(
4293 cast<Constant>(Val),
4294 isa<UndefValue>(Val) ||
4295 canCauseUndefinedBehavior(ToBePromoted, U.getOperandNo()));
4297 llvm_unreachable("Did you modified shouldPromote and forgot to update "
4299 ToBePromoted->setOperand(U.getOperandNo(), NewVal);
4301 Transition->removeFromParent();
4302 Transition->insertAfter(ToBePromoted);
4303 Transition->setOperand(getTransitionOriginalValueIdx(), ToBePromoted);
4306 /// Some targets can do store(extractelement) with one instruction.
4307 /// Try to push the extractelement towards the stores when the target
4308 /// has this feature and this is profitable.
4309 bool CodeGenPrepare::optimizeExtractElementInst(Instruction *Inst) {
4310 unsigned CombineCost = UINT_MAX;
4311 if (DisableStoreExtract || !TLI ||
4312 (!StressStoreExtract &&
4313 !TLI->canCombineStoreAndExtract(Inst->getOperand(0)->getType(),
4314 Inst->getOperand(1), CombineCost)))
4317 // At this point we know that Inst is a vector to scalar transition.
4318 // Try to move it down the def-use chain, until:
4319 // - We can combine the transition with its single use
4320 // => we got rid of the transition.
4321 // - We escape the current basic block
4322 // => we would need to check that we are moving it at a cheaper place and
4323 // we do not do that for now.
4324 BasicBlock *Parent = Inst->getParent();
4325 DEBUG(dbgs() << "Found an interesting transition: " << *Inst << '\n');
4326 VectorPromoteHelper VPH(*DL, *TLI, *TTI, Inst, CombineCost);
4327 // If the transition has more than one use, assume this is not going to be
4329 while (Inst->hasOneUse()) {
4330 Instruction *ToBePromoted = cast<Instruction>(*Inst->user_begin());
4331 DEBUG(dbgs() << "Use: " << *ToBePromoted << '\n');
4333 if (ToBePromoted->getParent() != Parent) {
4334 DEBUG(dbgs() << "Instruction to promote is in a different block ("
4335 << ToBePromoted->getParent()->getName()
4336 << ") than the transition (" << Parent->getName() << ").\n");
4340 if (VPH.canCombine(ToBePromoted)) {
4341 DEBUG(dbgs() << "Assume " << *Inst << '\n'
4342 << "will be combined with: " << *ToBePromoted << '\n');
4343 VPH.recordCombineInstruction(ToBePromoted);
4344 bool Changed = VPH.promote();
4345 NumStoreExtractExposed += Changed;
4349 DEBUG(dbgs() << "Try promoting.\n");
4350 if (!VPH.canPromote(ToBePromoted) || !VPH.shouldPromote(ToBePromoted))
4353 DEBUG(dbgs() << "Promoting is possible... Enqueue for promotion!\n");
4355 VPH.enqueueForPromotion(ToBePromoted);
4356 Inst = ToBePromoted;
4361 bool CodeGenPrepare::optimizeInst(Instruction *I, bool& ModifiedDT) {
4362 // Bail out if we inserted the instruction to prevent optimizations from
4363 // stepping on each other's toes.
4364 if (InsertedInsts.count(I))
4367 if (PHINode *P = dyn_cast<PHINode>(I)) {
4368 // It is possible for very late stage optimizations (such as SimplifyCFG)
4369 // to introduce PHI nodes too late to be cleaned up. If we detect such a
4370 // trivial PHI, go ahead and zap it here.
4371 if (Value *V = SimplifyInstruction(P, *DL, TLInfo, nullptr)) {
4372 P->replaceAllUsesWith(V);
4373 P->eraseFromParent();
4380 if (CastInst *CI = dyn_cast<CastInst>(I)) {
4381 // If the source of the cast is a constant, then this should have
4382 // already been constant folded. The only reason NOT to constant fold
4383 // it is if something (e.g. LSR) was careful to place the constant
4384 // evaluation in a block other than then one that uses it (e.g. to hoist
4385 // the address of globals out of a loop). If this is the case, we don't
4386 // want to forward-subst the cast.
4387 if (isa<Constant>(CI->getOperand(0)))
4390 if (TLI && OptimizeNoopCopyExpression(CI, *TLI, *DL))
4393 if (isa<ZExtInst>(I) || isa<SExtInst>(I)) {
4394 /// Sink a zext or sext into its user blocks if the target type doesn't
4395 /// fit in one register
4397 TLI->getTypeAction(CI->getContext(),
4398 TLI->getValueType(*DL, CI->getType())) ==
4399 TargetLowering::TypeExpandInteger) {
4400 return SinkCast(CI);
4402 bool MadeChange = moveExtToFormExtLoad(I);
4403 return MadeChange | optimizeExtUses(I);
4409 if (CmpInst *CI = dyn_cast<CmpInst>(I))
4410 if (!TLI || !TLI->hasMultipleConditionRegisters())
4411 return OptimizeCmpExpression(CI);
4413 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
4414 stripInvariantGroupMetadata(*LI);
4416 unsigned AS = LI->getPointerAddressSpace();
4417 return optimizeMemoryInst(I, I->getOperand(0), LI->getType(), AS);
4422 if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
4423 stripInvariantGroupMetadata(*SI);
4425 unsigned AS = SI->getPointerAddressSpace();
4426 return optimizeMemoryInst(I, SI->getOperand(1),
4427 SI->getOperand(0)->getType(), AS);
4432 BinaryOperator *BinOp = dyn_cast<BinaryOperator>(I);
4434 if (BinOp && (BinOp->getOpcode() == Instruction::AShr ||
4435 BinOp->getOpcode() == Instruction::LShr)) {
4436 ConstantInt *CI = dyn_cast<ConstantInt>(BinOp->getOperand(1));
4437 if (TLI && CI && TLI->hasExtractBitsInsn())
4438 return OptimizeExtractBits(BinOp, CI, *TLI, *DL);
4443 if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(I)) {
4444 if (GEPI->hasAllZeroIndices()) {
4445 /// The GEP operand must be a pointer, so must its result -> BitCast
4446 Instruction *NC = new BitCastInst(GEPI->getOperand(0), GEPI->getType(),
4447 GEPI->getName(), GEPI);
4448 GEPI->replaceAllUsesWith(NC);
4449 GEPI->eraseFromParent();
4451 optimizeInst(NC, ModifiedDT);
4457 if (CallInst *CI = dyn_cast<CallInst>(I))
4458 return optimizeCallInst(CI, ModifiedDT);
4460 if (SelectInst *SI = dyn_cast<SelectInst>(I))
4461 return optimizeSelectInst(SI);
4463 if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(I))
4464 return optimizeShuffleVectorInst(SVI);
4466 if (isa<ExtractElementInst>(I))
4467 return optimizeExtractElementInst(I);
4472 // In this pass we look for GEP and cast instructions that are used
4473 // across basic blocks and rewrite them to improve basic-block-at-a-time
4475 bool CodeGenPrepare::optimizeBlock(BasicBlock &BB, bool& ModifiedDT) {
4477 bool MadeChange = false;
4479 CurInstIterator = BB.begin();
4480 while (CurInstIterator != BB.end()) {
4481 MadeChange |= optimizeInst(CurInstIterator++, ModifiedDT);
4485 MadeChange |= dupRetToEnableTailCallOpts(&BB);
4490 // llvm.dbg.value is far away from the value then iSel may not be able
4491 // handle it properly. iSel will drop llvm.dbg.value if it can not
4492 // find a node corresponding to the value.
4493 bool CodeGenPrepare::placeDbgValues(Function &F) {
4494 bool MadeChange = false;
4495 for (BasicBlock &BB : F) {
4496 Instruction *PrevNonDbgInst = nullptr;
4497 for (BasicBlock::iterator BI = BB.begin(), BE = BB.end(); BI != BE;) {
4498 Instruction *Insn = BI++;
4499 DbgValueInst *DVI = dyn_cast<DbgValueInst>(Insn);
4500 // Leave dbg.values that refer to an alloca alone. These
4501 // instrinsics describe the address of a variable (= the alloca)
4502 // being taken. They should not be moved next to the alloca
4503 // (and to the beginning of the scope), but rather stay close to
4504 // where said address is used.
4505 if (!DVI || (DVI->getValue() && isa<AllocaInst>(DVI->getValue()))) {
4506 PrevNonDbgInst = Insn;
4510 Instruction *VI = dyn_cast_or_null<Instruction>(DVI->getValue());
4511 if (VI && VI != PrevNonDbgInst && !VI->isTerminator()) {
4512 DEBUG(dbgs() << "Moving Debug Value before :\n" << *DVI << ' ' << *VI);
4513 DVI->removeFromParent();
4514 if (isa<PHINode>(VI))
4515 DVI->insertBefore(VI->getParent()->getFirstInsertionPt());
4517 DVI->insertAfter(VI);
4526 // If there is a sequence that branches based on comparing a single bit
4527 // against zero that can be combined into a single instruction, and the
4528 // target supports folding these into a single instruction, sink the
4529 // mask and compare into the branch uses. Do this before OptimizeBlock ->
4530 // OptimizeInst -> OptimizeCmpExpression, which perturbs the pattern being
4532 bool CodeGenPrepare::sinkAndCmp(Function &F) {
4533 if (!EnableAndCmpSinking)
4535 if (!TLI || !TLI->isMaskAndBranchFoldingLegal())
4537 bool MadeChange = false;
4538 for (Function::iterator I = F.begin(), E = F.end(); I != E; ) {
4539 BasicBlock *BB = I++;
4541 // Does this BB end with the following?
4542 // %andVal = and %val, #single-bit-set
4543 // %icmpVal = icmp %andResult, 0
4544 // br i1 %cmpVal label %dest1, label %dest2"
4545 BranchInst *Brcc = dyn_cast<BranchInst>(BB->getTerminator());
4546 if (!Brcc || !Brcc->isConditional())
4548 ICmpInst *Cmp = dyn_cast<ICmpInst>(Brcc->getOperand(0));
4549 if (!Cmp || Cmp->getParent() != BB)
4551 ConstantInt *Zero = dyn_cast<ConstantInt>(Cmp->getOperand(1));
4552 if (!Zero || !Zero->isZero())
4554 Instruction *And = dyn_cast<Instruction>(Cmp->getOperand(0));
4555 if (!And || And->getOpcode() != Instruction::And || And->getParent() != BB)
4557 ConstantInt* Mask = dyn_cast<ConstantInt>(And->getOperand(1));
4558 if (!Mask || !Mask->getUniqueInteger().isPowerOf2())
4560 DEBUG(dbgs() << "found and; icmp ?,0; brcc\n"); DEBUG(BB->dump());
4562 // Push the "and; icmp" for any users that are conditional branches.
4563 // Since there can only be one branch use per BB, we don't need to keep
4564 // track of which BBs we insert into.
4565 for (Value::use_iterator UI = Cmp->use_begin(), E = Cmp->use_end();
4569 BranchInst *BrccUser = dyn_cast<BranchInst>(*UI);
4571 if (!BrccUser || !BrccUser->isConditional())
4573 BasicBlock *UserBB = BrccUser->getParent();
4574 if (UserBB == BB) continue;
4575 DEBUG(dbgs() << "found Brcc use\n");
4577 // Sink the "and; icmp" to use.
4579 BinaryOperator *NewAnd =
4580 BinaryOperator::CreateAnd(And->getOperand(0), And->getOperand(1), "",
4583 CmpInst::Create(Cmp->getOpcode(), Cmp->getPredicate(), NewAnd, Zero,
4587 DEBUG(BrccUser->getParent()->dump());
4593 /// \brief Retrieve the probabilities of a conditional branch. Returns true on
4594 /// success, or returns false if no or invalid metadata was found.
4595 static bool extractBranchMetadata(BranchInst *BI,
4596 uint64_t &ProbTrue, uint64_t &ProbFalse) {
4597 assert(BI->isConditional() &&
4598 "Looking for probabilities on unconditional branch?");
4599 auto *ProfileData = BI->getMetadata(LLVMContext::MD_prof);
4600 if (!ProfileData || ProfileData->getNumOperands() != 3)
4603 const auto *CITrue =
4604 mdconst::dyn_extract<ConstantInt>(ProfileData->getOperand(1));
4605 const auto *CIFalse =
4606 mdconst::dyn_extract<ConstantInt>(ProfileData->getOperand(2));
4607 if (!CITrue || !CIFalse)
4610 ProbTrue = CITrue->getValue().getZExtValue();
4611 ProbFalse = CIFalse->getValue().getZExtValue();
4616 /// \brief Scale down both weights to fit into uint32_t.
4617 static void scaleWeights(uint64_t &NewTrue, uint64_t &NewFalse) {
4618 uint64_t NewMax = (NewTrue > NewFalse) ? NewTrue : NewFalse;
4619 uint32_t Scale = (NewMax / UINT32_MAX) + 1;
4620 NewTrue = NewTrue / Scale;
4621 NewFalse = NewFalse / Scale;
4624 /// \brief Some targets prefer to split a conditional branch like:
4626 /// %0 = icmp ne i32 %a, 0
4627 /// %1 = icmp ne i32 %b, 0
4628 /// %or.cond = or i1 %0, %1
4629 /// br i1 %or.cond, label %TrueBB, label %FalseBB
4631 /// into multiple branch instructions like:
4634 /// %0 = icmp ne i32 %a, 0
4635 /// br i1 %0, label %TrueBB, label %bb2
4637 /// %1 = icmp ne i32 %b, 0
4638 /// br i1 %1, label %TrueBB, label %FalseBB
4640 /// This usually allows instruction selection to do even further optimizations
4641 /// and combine the compare with the branch instruction. Currently this is
4642 /// applied for targets which have "cheap" jump instructions.
4644 /// FIXME: Remove the (equivalent?) implementation in SelectionDAG.
4646 bool CodeGenPrepare::splitBranchCondition(Function &F) {
4647 if (!TM || !TM->Options.EnableFastISel || !TLI || TLI->isJumpExpensive())
4650 bool MadeChange = false;
4651 for (auto &BB : F) {
4652 // Does this BB end with the following?
4653 // %cond1 = icmp|fcmp|binary instruction ...
4654 // %cond2 = icmp|fcmp|binary instruction ...
4655 // %cond.or = or|and i1 %cond1, cond2
4656 // br i1 %cond.or label %dest1, label %dest2"
4657 BinaryOperator *LogicOp;
4658 BasicBlock *TBB, *FBB;
4659 if (!match(BB.getTerminator(), m_Br(m_OneUse(m_BinOp(LogicOp)), TBB, FBB)))
4662 auto *Br1 = cast<BranchInst>(BB.getTerminator());
4663 if (Br1->getMetadata(LLVMContext::MD_unpredictable))
4667 Value *Cond1, *Cond2;
4668 if (match(LogicOp, m_And(m_OneUse(m_Value(Cond1)),
4669 m_OneUse(m_Value(Cond2)))))
4670 Opc = Instruction::And;
4671 else if (match(LogicOp, m_Or(m_OneUse(m_Value(Cond1)),
4672 m_OneUse(m_Value(Cond2)))))
4673 Opc = Instruction::Or;
4677 if (!match(Cond1, m_CombineOr(m_Cmp(), m_BinOp())) ||
4678 !match(Cond2, m_CombineOr(m_Cmp(), m_BinOp())) )
4681 DEBUG(dbgs() << "Before branch condition splitting\n"; BB.dump());
4684 auto *InsertBefore = std::next(Function::iterator(BB))
4685 .getNodePtrUnchecked();
4686 auto TmpBB = BasicBlock::Create(BB.getContext(),
4687 BB.getName() + ".cond.split",
4688 BB.getParent(), InsertBefore);
4690 // Update original basic block by using the first condition directly by the
4691 // branch instruction and removing the no longer needed and/or instruction.
4692 Br1->setCondition(Cond1);
4693 LogicOp->eraseFromParent();
4695 // Depending on the conditon we have to either replace the true or the false
4696 // successor of the original branch instruction.
4697 if (Opc == Instruction::And)
4698 Br1->setSuccessor(0, TmpBB);
4700 Br1->setSuccessor(1, TmpBB);
4702 // Fill in the new basic block.
4703 auto *Br2 = IRBuilder<>(TmpBB).CreateCondBr(Cond2, TBB, FBB);
4704 if (auto *I = dyn_cast<Instruction>(Cond2)) {
4705 I->removeFromParent();
4706 I->insertBefore(Br2);
4709 // Update PHI nodes in both successors. The original BB needs to be
4710 // replaced in one succesor's PHI nodes, because the branch comes now from
4711 // the newly generated BB (NewBB). In the other successor we need to add one
4712 // incoming edge to the PHI nodes, because both branch instructions target
4713 // now the same successor. Depending on the original branch condition
4714 // (and/or) we have to swap the successors (TrueDest, FalseDest), so that
4715 // we perfrom the correct update for the PHI nodes.
4716 // This doesn't change the successor order of the just created branch
4717 // instruction (or any other instruction).
4718 if (Opc == Instruction::Or)
4719 std::swap(TBB, FBB);
4721 // Replace the old BB with the new BB.
4722 for (auto &I : *TBB) {
4723 PHINode *PN = dyn_cast<PHINode>(&I);
4727 while ((i = PN->getBasicBlockIndex(&BB)) >= 0)
4728 PN->setIncomingBlock(i, TmpBB);
4731 // Add another incoming edge form the new BB.
4732 for (auto &I : *FBB) {
4733 PHINode *PN = dyn_cast<PHINode>(&I);
4736 auto *Val = PN->getIncomingValueForBlock(&BB);
4737 PN->addIncoming(Val, TmpBB);
4740 // Update the branch weights (from SelectionDAGBuilder::
4741 // FindMergedConditions).
4742 if (Opc == Instruction::Or) {
4743 // Codegen X | Y as:
4752 // We have flexibility in setting Prob for BB1 and Prob for NewBB.
4753 // The requirement is that
4754 // TrueProb for BB1 + (FalseProb for BB1 * TrueProb for TmpBB)
4755 // = TrueProb for orignal BB.
4756 // Assuming the orignal weights are A and B, one choice is to set BB1's
4757 // weights to A and A+2B, and set TmpBB's weights to A and 2B. This choice
4759 // TrueProb for BB1 == FalseProb for BB1 * TrueProb for TmpBB.
4760 // Another choice is to assume TrueProb for BB1 equals to TrueProb for
4761 // TmpBB, but the math is more complicated.
4762 uint64_t TrueWeight, FalseWeight;
4763 if (extractBranchMetadata(Br1, TrueWeight, FalseWeight)) {
4764 uint64_t NewTrueWeight = TrueWeight;
4765 uint64_t NewFalseWeight = TrueWeight + 2 * FalseWeight;
4766 scaleWeights(NewTrueWeight, NewFalseWeight);
4767 Br1->setMetadata(LLVMContext::MD_prof, MDBuilder(Br1->getContext())
4768 .createBranchWeights(TrueWeight, FalseWeight));
4770 NewTrueWeight = TrueWeight;
4771 NewFalseWeight = 2 * FalseWeight;
4772 scaleWeights(NewTrueWeight, NewFalseWeight);
4773 Br2->setMetadata(LLVMContext::MD_prof, MDBuilder(Br2->getContext())
4774 .createBranchWeights(TrueWeight, FalseWeight));
4777 // Codegen X & Y as:
4785 // This requires creation of TmpBB after CurBB.
4787 // We have flexibility in setting Prob for BB1 and Prob for TmpBB.
4788 // The requirement is that
4789 // FalseProb for BB1 + (TrueProb for BB1 * FalseProb for TmpBB)
4790 // = FalseProb for orignal BB.
4791 // Assuming the orignal weights are A and B, one choice is to set BB1's
4792 // weights to 2A+B and B, and set TmpBB's weights to 2A and B. This choice
4794 // FalseProb for BB1 == TrueProb for BB1 * FalseProb for TmpBB.
4795 uint64_t TrueWeight, FalseWeight;
4796 if (extractBranchMetadata(Br1, TrueWeight, FalseWeight)) {
4797 uint64_t NewTrueWeight = 2 * TrueWeight + FalseWeight;
4798 uint64_t NewFalseWeight = FalseWeight;
4799 scaleWeights(NewTrueWeight, NewFalseWeight);
4800 Br1->setMetadata(LLVMContext::MD_prof, MDBuilder(Br1->getContext())
4801 .createBranchWeights(TrueWeight, FalseWeight));
4803 NewTrueWeight = 2 * TrueWeight;
4804 NewFalseWeight = FalseWeight;
4805 scaleWeights(NewTrueWeight, NewFalseWeight);
4806 Br2->setMetadata(LLVMContext::MD_prof, MDBuilder(Br2->getContext())
4807 .createBranchWeights(TrueWeight, FalseWeight));
4811 // Note: No point in getting fancy here, since the DT info is never
4812 // available to CodeGenPrepare.
4817 DEBUG(dbgs() << "After branch condition splitting\n"; BB.dump();
4823 void CodeGenPrepare::stripInvariantGroupMetadata(Instruction &I) {
4824 if (auto *InvariantMD = I.getMetadata(LLVMContext::MD_invariant_group))
4825 I.dropUnknownNonDebugMetadata(InvariantMD->getMetadataID());