Bug Summary

File:lib/CodeGen/CodeGenPrepare.cpp
Warning:line 5203, column 3
Undefined or garbage value returned to caller

Annotated Source Code

1//===- CodeGenPrepare.cpp - Prepare a function for code generation --------===//
2//
3// The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
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.
13//
14//===----------------------------------------------------------------------===//
15
16#include "llvm/CodeGen/Passes.h"
17#include "llvm/ADT/DenseMap.h"
18#include "llvm/ADT/SetVector.h"
19#include "llvm/ADT/SmallSet.h"
20#include "llvm/ADT/Statistic.h"
21#include "llvm/Analysis/BlockFrequencyInfo.h"
22#include "llvm/Analysis/BranchProbabilityInfo.h"
23#include "llvm/Analysis/CFG.h"
24#include "llvm/Analysis/InstructionSimplify.h"
25#include "llvm/Analysis/LoopInfo.h"
26#include "llvm/Analysis/ProfileSummaryInfo.h"
27#include "llvm/Analysis/TargetLibraryInfo.h"
28#include "llvm/Analysis/TargetTransformInfo.h"
29#include "llvm/Analysis/ValueTracking.h"
30#include "llvm/Analysis/MemoryBuiltins.h"
31#include "llvm/CodeGen/Analysis.h"
32#include "llvm/IR/CallSite.h"
33#include "llvm/IR/Constants.h"
34#include "llvm/IR/DataLayout.h"
35#include "llvm/IR/DerivedTypes.h"
36#include "llvm/IR/Dominators.h"
37#include "llvm/IR/Function.h"
38#include "llvm/IR/GetElementPtrTypeIterator.h"
39#include "llvm/IR/IRBuilder.h"
40#include "llvm/IR/InlineAsm.h"
41#include "llvm/IR/Instructions.h"
42#include "llvm/IR/IntrinsicInst.h"
43#include "llvm/IR/MDBuilder.h"
44#include "llvm/IR/PatternMatch.h"
45#include "llvm/IR/Statepoint.h"
46#include "llvm/IR/ValueHandle.h"
47#include "llvm/IR/ValueMap.h"
48#include "llvm/Pass.h"
49#include "llvm/Support/BranchProbability.h"
50#include "llvm/Support/CommandLine.h"
51#include "llvm/Support/Debug.h"
52#include "llvm/Support/raw_ostream.h"
53#include "llvm/Target/TargetLowering.h"
54#include "llvm/Target/TargetSubtargetInfo.h"
55#include "llvm/Transforms/Utils/BasicBlockUtils.h"
56#include "llvm/Transforms/Utils/BuildLibCalls.h"
57#include "llvm/Transforms/Utils/BypassSlowDivision.h"
58#include "llvm/Transforms/Utils/Cloning.h"
59#include "llvm/Transforms/Utils/Local.h"
60#include "llvm/Transforms/Utils/SimplifyLibCalls.h"
61#include "llvm/Transforms/Utils/ValueMapper.h"
62using namespace llvm;
63using namespace llvm::PatternMatch;
64
65#define DEBUG_TYPE"codegenprepare" "codegenprepare"
66
67STATISTIC(NumBlocksElim, "Number of blocks eliminated")static llvm::Statistic NumBlocksElim = {"codegenprepare", "NumBlocksElim"
, "Number of blocks eliminated", {0}, false}
;
68STATISTIC(NumPHIsElim, "Number of trivial PHIs eliminated")static llvm::Statistic NumPHIsElim = {"codegenprepare", "NumPHIsElim"
, "Number of trivial PHIs eliminated", {0}, false}
;
69STATISTIC(NumGEPsElim, "Number of GEPs converted to casts")static llvm::Statistic NumGEPsElim = {"codegenprepare", "NumGEPsElim"
, "Number of GEPs converted to casts", {0}, false}
;
70STATISTIC(NumCmpUses, "Number of uses of Cmp expressions replaced with uses of "static llvm::Statistic NumCmpUses = {"codegenprepare", "NumCmpUses"
, "Number of uses of Cmp expressions replaced with uses of " "sunken Cmps"
, {0}, false}
71 "sunken Cmps")static llvm::Statistic NumCmpUses = {"codegenprepare", "NumCmpUses"
, "Number of uses of Cmp expressions replaced with uses of " "sunken Cmps"
, {0}, false}
;
72STATISTIC(NumCastUses, "Number of uses of Cast expressions replaced with uses "static llvm::Statistic NumCastUses = {"codegenprepare", "NumCastUses"
, "Number of uses of Cast expressions replaced with uses " "of sunken Casts"
, {0}, false}
73 "of sunken Casts")static llvm::Statistic NumCastUses = {"codegenprepare", "NumCastUses"
, "Number of uses of Cast expressions replaced with uses " "of sunken Casts"
, {0}, false}
;
74STATISTIC(NumMemoryInsts, "Number of memory instructions whose address "static llvm::Statistic NumMemoryInsts = {"codegenprepare", "NumMemoryInsts"
, "Number of memory instructions whose address " "computations were sunk"
, {0}, false}
75 "computations were sunk")static llvm::Statistic NumMemoryInsts = {"codegenprepare", "NumMemoryInsts"
, "Number of memory instructions whose address " "computations were sunk"
, {0}, false}
;
76STATISTIC(NumExtsMoved, "Number of [s|z]ext instructions combined with loads")static llvm::Statistic NumExtsMoved = {"codegenprepare", "NumExtsMoved"
, "Number of [s|z]ext instructions combined with loads", {0},
false}
;
77STATISTIC(NumExtUses, "Number of uses of [s|z]ext instructions optimized")static llvm::Statistic NumExtUses = {"codegenprepare", "NumExtUses"
, "Number of uses of [s|z]ext instructions optimized", {0}, false
}
;
78STATISTIC(NumAndsAdded,static llvm::Statistic NumAndsAdded = {"codegenprepare", "NumAndsAdded"
, "Number of and mask instructions added to form ext loads", {
0}, false}
79 "Number of and mask instructions added to form ext loads")static llvm::Statistic NumAndsAdded = {"codegenprepare", "NumAndsAdded"
, "Number of and mask instructions added to form ext loads", {
0}, false}
;
80STATISTIC(NumAndUses, "Number of uses of and mask instructions optimized")static llvm::Statistic NumAndUses = {"codegenprepare", "NumAndUses"
, "Number of uses of and mask instructions optimized", {0}, false
}
;
81STATISTIC(NumRetsDup, "Number of return instructions duplicated")static llvm::Statistic NumRetsDup = {"codegenprepare", "NumRetsDup"
, "Number of return instructions duplicated", {0}, false}
;
82STATISTIC(NumDbgValueMoved, "Number of debug value instructions moved")static llvm::Statistic NumDbgValueMoved = {"codegenprepare", "NumDbgValueMoved"
, "Number of debug value instructions moved", {0}, false}
;
83STATISTIC(NumSelectsExpanded, "Number of selects turned into branches")static llvm::Statistic NumSelectsExpanded = {"codegenprepare"
, "NumSelectsExpanded", "Number of selects turned into branches"
, {0}, false}
;
84STATISTIC(NumStoreExtractExposed, "Number of store(extractelement) exposed")static llvm::Statistic NumStoreExtractExposed = {"codegenprepare"
, "NumStoreExtractExposed", "Number of store(extractelement) exposed"
, {0}, false}
;
85
86static cl::opt<bool> DisableBranchOpts(
87 "disable-cgp-branch-opts", cl::Hidden, cl::init(false),
88 cl::desc("Disable branch optimizations in CodeGenPrepare"));
89
90static cl::opt<bool>
91 DisableGCOpts("disable-cgp-gc-opts", cl::Hidden, cl::init(false),
92 cl::desc("Disable GC optimizations in CodeGenPrepare"));
93
94static cl::opt<bool> DisableSelectToBranch(
95 "disable-cgp-select2branch", cl::Hidden, cl::init(false),
96 cl::desc("Disable select to branch conversion."));
97
98static cl::opt<bool> AddrSinkUsingGEPs(
99 "addr-sink-using-gep", cl::Hidden, cl::init(true),
100 cl::desc("Address sinking in CGP using GEPs."));
101
102static cl::opt<bool> EnableAndCmpSinking(
103 "enable-andcmp-sinking", cl::Hidden, cl::init(true),
104 cl::desc("Enable sinkinig and/cmp into branches."));
105
106static cl::opt<bool> DisableStoreExtract(
107 "disable-cgp-store-extract", cl::Hidden, cl::init(false),
108 cl::desc("Disable store(extract) optimizations in CodeGenPrepare"));
109
110static cl::opt<bool> StressStoreExtract(
111 "stress-cgp-store-extract", cl::Hidden, cl::init(false),
112 cl::desc("Stress test store(extract) optimizations in CodeGenPrepare"));
113
114static cl::opt<bool> DisableExtLdPromotion(
115 "disable-cgp-ext-ld-promotion", cl::Hidden, cl::init(false),
116 cl::desc("Disable ext(promotable(ld)) -> promoted(ext(ld)) optimization in "
117 "CodeGenPrepare"));
118
119static cl::opt<bool> StressExtLdPromotion(
120 "stress-cgp-ext-ld-promotion", cl::Hidden, cl::init(false),
121 cl::desc("Stress test ext(promotable(ld)) -> promoted(ext(ld)) "
122 "optimization in CodeGenPrepare"));
123
124static cl::opt<bool> DisablePreheaderProtect(
125 "disable-preheader-prot", cl::Hidden, cl::init(false),
126 cl::desc("Disable protection against removing loop preheaders"));
127
128static cl::opt<bool> ProfileGuidedSectionPrefix(
129 "profile-guided-section-prefix", cl::Hidden, cl::init(true),
130 cl::desc("Use profile info to add section prefix for hot/cold functions"));
131
132static cl::opt<unsigned> FreqRatioToSkipMerge(
133 "cgp-freq-ratio-to-skip-merge", cl::Hidden, cl::init(2),
134 cl::desc("Skip merging empty blocks if (frequency of empty block) / "
135 "(frequency of destination block) is greater than this ratio"));
136
137static cl::opt<bool> ForceSplitStore(
138 "force-split-store", cl::Hidden, cl::init(false),
139 cl::desc("Force store splitting no matter what the target query says."));
140
141static cl::opt<bool>
142EnableTypePromotionMerge("cgp-type-promotion-merge", cl::Hidden,
143 cl::desc("Enable merging of redundant sexts when one is dominating"
144 " the other."), cl::init(true));
145
146namespace {
147typedef SmallPtrSet<Instruction *, 16> SetOfInstrs;
148typedef PointerIntPair<Type *, 1, bool> TypeIsSExt;
149typedef DenseMap<Instruction *, TypeIsSExt> InstrToOrigTy;
150typedef SmallVector<Instruction *, 16> SExts;
151typedef DenseMap<Value *, SExts> ValueToSExts;
152class TypePromotionTransaction;
153
154 class CodeGenPrepare : public FunctionPass {
155 const TargetMachine *TM;
156 const TargetSubtargetInfo *SubtargetInfo;
157 const TargetLowering *TLI;
158 const TargetRegisterInfo *TRI;
159 const TargetTransformInfo *TTI;
160 const TargetLibraryInfo *TLInfo;
161 const LoopInfo *LI;
162 std::unique_ptr<BlockFrequencyInfo> BFI;
163 std::unique_ptr<BranchProbabilityInfo> BPI;
164
165 /// As we scan instructions optimizing them, this is the next instruction
166 /// to optimize. Transforms that can invalidate this should update it.
167 BasicBlock::iterator CurInstIterator;
168
169 /// Keeps track of non-local addresses that have been sunk into a block.
170 /// This allows us to avoid inserting duplicate code for blocks with
171 /// multiple load/stores of the same address.
172 ValueMap<Value*, Value*> SunkAddrs;
173
174 /// Keeps track of all instructions inserted for the current function.
175 SetOfInstrs InsertedInsts;
176 /// Keeps track of the type of the related instruction before their
177 /// promotion for the current function.
178 InstrToOrigTy PromotedInsts;
179
180 /// Keep track of instructions removed during promotion.
181 SetOfInstrs RemovedInsts;
182
183 /// Keep track of sext chains based on their initial value.
184 DenseMap<Value *, Instruction *> SeenChainsForSExt;
185
186 /// Keep track of SExt promoted.
187 ValueToSExts ValToSExtendedUses;
188
189 /// True if CFG is modified in any way.
190 bool ModifiedDT;
191
192 /// True if optimizing for size.
193 bool OptSize;
194
195 /// DataLayout for the Function being processed.
196 const DataLayout *DL;
197
198 public:
199 static char ID; // Pass identification, replacement for typeid
200 explicit CodeGenPrepare(const TargetMachine *TM = nullptr)
201 : FunctionPass(ID), TM(TM), TLI(nullptr), TTI(nullptr), DL(nullptr) {
202 initializeCodeGenPreparePass(*PassRegistry::getPassRegistry());
203 }
204 bool runOnFunction(Function &F) override;
205
206 StringRef getPassName() const override { return "CodeGen Prepare"; }
207
208 void getAnalysisUsage(AnalysisUsage &AU) const override {
209 // FIXME: When we can selectively preserve passes, preserve the domtree.
210 AU.addRequired<ProfileSummaryInfoWrapperPass>();
211 AU.addRequired<TargetLibraryInfoWrapperPass>();
212 AU.addRequired<TargetTransformInfoWrapperPass>();
213 AU.addRequired<LoopInfoWrapperPass>();
214 }
215
216 private:
217 bool eliminateFallThrough(Function &F);
218 bool eliminateMostlyEmptyBlocks(Function &F);
219 BasicBlock *findDestBlockOfMergeableEmptyBlock(BasicBlock *BB);
220 bool canMergeBlocks(const BasicBlock *BB, const BasicBlock *DestBB) const;
221 void eliminateMostlyEmptyBlock(BasicBlock *BB);
222 bool isMergingEmptyBlockProfitable(BasicBlock *BB, BasicBlock *DestBB,
223 bool isPreheader);
224 bool optimizeBlock(BasicBlock &BB, bool& ModifiedDT);
225 bool optimizeInst(Instruction *I, bool& ModifiedDT);
226 bool optimizeMemoryInst(Instruction *I, Value *Addr,
227 Type *AccessTy, unsigned AS);
228 bool optimizeInlineAsmInst(CallInst *CS);
229 bool optimizeCallInst(CallInst *CI, bool& ModifiedDT);
230 bool optimizeExt(Instruction *&I);
231 bool optimizeExtUses(Instruction *I);
232 bool optimizeLoadExt(LoadInst *I);
233 bool optimizeSelectInst(SelectInst *SI);
234 bool optimizeShuffleVectorInst(ShuffleVectorInst *SI);
235 bool optimizeSwitchInst(SwitchInst *CI);
236 bool optimizeExtractElementInst(Instruction *Inst);
237 bool dupRetToEnableTailCallOpts(BasicBlock *BB);
238 bool placeDbgValues(Function &F);
239 bool canFormExtLd(const SmallVectorImpl<Instruction *> &MovedExts,
240 LoadInst *&LI, Instruction *&Inst, bool HasPromoted);
241 bool tryToPromoteExts(TypePromotionTransaction &TPT,
242 const SmallVectorImpl<Instruction *> &Exts,
243 SmallVectorImpl<Instruction *> &ProfitablyMovedExts,
244 unsigned CreatedInstsCost = 0);
245 bool mergeSExts(Function &F);
246 bool performAddressTypePromotion(
247 Instruction *&Inst,
248 bool AllowPromotionWithoutCommonHeader,
249 bool HasPromoted, TypePromotionTransaction &TPT,
250 SmallVectorImpl<Instruction *> &SpeculativelyMovedExts);
251 bool splitBranchCondition(Function &F);
252 bool simplifyOffsetableRelocate(Instruction &I);
253 bool splitIndirectCriticalEdges(Function &F);
254 };
255}
256
257char CodeGenPrepare::ID = 0;
258INITIALIZE_TM_PASS_BEGIN(CodeGenPrepare, "codegenprepare",static void *initializeCodeGenPreparePassOnce(PassRegistry &
Registry) {
259 "Optimize for code generation", false, false)static void *initializeCodeGenPreparePassOnce(PassRegistry &
Registry) {
260INITIALIZE_PASS_DEPENDENCY(ProfileSummaryInfoWrapperPass)initializeProfileSummaryInfoWrapperPassPass(Registry);
261INITIALIZE_TM_PASS_END(CodeGenPrepare, "codegenprepare",PassInfo *PI = new PassInfo( "Optimize for code generation", "codegenprepare"
, &CodeGenPrepare::ID, PassInfo::NormalCtor_t(callDefaultCtor
<CodeGenPrepare>), false, false, PassInfo::TargetMachineCtor_t
(callTargetMachineCtor<CodeGenPrepare>)); Registry.registerPass
(*PI, true); return PI; } static llvm::once_flag InitializeCodeGenPreparePassFlag
; void llvm::initializeCodeGenPreparePass(PassRegistry &Registry
) { llvm::call_once(InitializeCodeGenPreparePassFlag, initializeCodeGenPreparePassOnce
, std::ref(Registry)); }
262 "Optimize for code generation", false, false)PassInfo *PI = new PassInfo( "Optimize for code generation", "codegenprepare"
, &CodeGenPrepare::ID, PassInfo::NormalCtor_t(callDefaultCtor
<CodeGenPrepare>), false, false, PassInfo::TargetMachineCtor_t
(callTargetMachineCtor<CodeGenPrepare>)); Registry.registerPass
(*PI, true); return PI; } static llvm::once_flag InitializeCodeGenPreparePassFlag
; void llvm::initializeCodeGenPreparePass(PassRegistry &Registry
) { llvm::call_once(InitializeCodeGenPreparePassFlag, initializeCodeGenPreparePassOnce
, std::ref(Registry)); }
263
264FunctionPass *llvm::createCodeGenPreparePass(const TargetMachine *TM) {
265 return new CodeGenPrepare(TM);
266}
267
268bool CodeGenPrepare::runOnFunction(Function &F) {
269 if (skipFunction(F))
270 return false;
271
272 DL = &F.getParent()->getDataLayout();
273
274 bool EverMadeChange = false;
275 // Clear per function information.
276 InsertedInsts.clear();
277 PromotedInsts.clear();
278 BFI.reset();
279 BPI.reset();
280
281 ModifiedDT = false;
282 if (TM) {
283 SubtargetInfo = TM->getSubtargetImpl(F);
284 TLI = SubtargetInfo->getTargetLowering();
285 TRI = SubtargetInfo->getRegisterInfo();
286 }
287 TLInfo = &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
288 TTI = &getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
289 LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
290 OptSize = F.optForSize();
291
292 if (ProfileGuidedSectionPrefix) {
293 ProfileSummaryInfo *PSI =
294 getAnalysis<ProfileSummaryInfoWrapperPass>().getPSI();
295 if (PSI->isFunctionHotInCallGraph(&F))
296 F.setSectionPrefix(".hot");
297 else if (PSI->isFunctionColdInCallGraph(&F))
298 F.setSectionPrefix(".cold");
299 }
300
301 /// This optimization identifies DIV instructions that can be
302 /// profitably bypassed and carried out with a shorter, faster divide.
303 if (!OptSize && TLI && TLI->isSlowDivBypassed()) {
304 const DenseMap<unsigned int, unsigned int> &BypassWidths =
305 TLI->getBypassSlowDivWidths();
306 BasicBlock* BB = &*F.begin();
307 while (BB != nullptr) {
308 // bypassSlowDivision may create new BBs, but we don't want to reapply the
309 // optimization to those blocks.
310 BasicBlock* Next = BB->getNextNode();
311 EverMadeChange |= bypassSlowDivision(BB, BypassWidths);
312 BB = Next;
313 }
314 }
315
316 // Eliminate blocks that contain only PHI nodes and an
317 // unconditional branch.
318 EverMadeChange |= eliminateMostlyEmptyBlocks(F);
319
320 // llvm.dbg.value is far away from the value then iSel may not be able
321 // handle it properly. iSel will drop llvm.dbg.value if it can not
322 // find a node corresponding to the value.
323 EverMadeChange |= placeDbgValues(F);
324
325 if (!DisableBranchOpts)
326 EverMadeChange |= splitBranchCondition(F);
327
328 // Split some critical edges where one of the sources is an indirect branch,
329 // to help generate sane code for PHIs involving such edges.
330 EverMadeChange |= splitIndirectCriticalEdges(F);
331
332 bool MadeChange = true;
333 while (MadeChange) {
334 MadeChange = false;
335 SeenChainsForSExt.clear();
336 ValToSExtendedUses.clear();
337 RemovedInsts.clear();
338 for (Function::iterator I = F.begin(); I != F.end(); ) {
339 BasicBlock *BB = &*I++;
340 bool ModifiedDTOnIteration = false;
341 MadeChange |= optimizeBlock(*BB, ModifiedDTOnIteration);
342
343 // Restart BB iteration if the dominator tree of the Function was changed
344 if (ModifiedDTOnIteration)
345 break;
346 }
347 if (EnableTypePromotionMerge && !ValToSExtendedUses.empty())
348 MadeChange |= mergeSExts(F);
349
350 // Really free removed instructions during promotion.
351 for (Instruction *I : RemovedInsts)
352 delete I;
353
354 EverMadeChange |= MadeChange;
355 }
356
357 SunkAddrs.clear();
358
359 if (!DisableBranchOpts) {
360 MadeChange = false;
361 SmallPtrSet<BasicBlock*, 8> WorkList;
362 for (BasicBlock &BB : F) {
363 SmallVector<BasicBlock *, 2> Successors(succ_begin(&BB), succ_end(&BB));
364 MadeChange |= ConstantFoldTerminator(&BB, true);
365 if (!MadeChange) continue;
366
367 for (SmallVectorImpl<BasicBlock*>::iterator
368 II = Successors.begin(), IE = Successors.end(); II != IE; ++II)
369 if (pred_begin(*II) == pred_end(*II))
370 WorkList.insert(*II);
371 }
372
373 // Delete the dead blocks and any of their dead successors.
374 MadeChange |= !WorkList.empty();
375 while (!WorkList.empty()) {
376 BasicBlock *BB = *WorkList.begin();
377 WorkList.erase(BB);
378 SmallVector<BasicBlock*, 2> Successors(succ_begin(BB), succ_end(BB));
379
380 DeleteDeadBlock(BB);
381
382 for (SmallVectorImpl<BasicBlock*>::iterator
383 II = Successors.begin(), IE = Successors.end(); II != IE; ++II)
384 if (pred_begin(*II) == pred_end(*II))
385 WorkList.insert(*II);
386 }
387
388 // Merge pairs of basic blocks with unconditional branches, connected by
389 // a single edge.
390 if (EverMadeChange || MadeChange)
391 MadeChange |= eliminateFallThrough(F);
392
393 EverMadeChange |= MadeChange;
394 }
395
396 if (!DisableGCOpts) {
397 SmallVector<Instruction *, 2> Statepoints;
398 for (BasicBlock &BB : F)
399 for (Instruction &I : BB)
400 if (isStatepoint(I))
401 Statepoints.push_back(&I);
402 for (auto &I : Statepoints)
403 EverMadeChange |= simplifyOffsetableRelocate(*I);
404 }
405
406 return EverMadeChange;
407}
408
409/// Merge basic blocks which are connected by a single edge, where one of the
410/// basic blocks has a single successor pointing to the other basic block,
411/// which has a single predecessor.
412bool CodeGenPrepare::eliminateFallThrough(Function &F) {
413 bool Changed = false;
414 // Scan all of the blocks in the function, except for the entry block.
415 for (Function::iterator I = std::next(F.begin()), E = F.end(); I != E;) {
416 BasicBlock *BB = &*I++;
417 // If the destination block has a single pred, then this is a trivial
418 // edge, just collapse it.
419 BasicBlock *SinglePred = BB->getSinglePredecessor();
420
421 // Don't merge if BB's address is taken.
422 if (!SinglePred || SinglePred == BB || BB->hasAddressTaken()) continue;
423
424 BranchInst *Term = dyn_cast<BranchInst>(SinglePred->getTerminator());
425 if (Term && !Term->isConditional()) {
426 Changed = true;
427 DEBUG(dbgs() << "To merge:\n"<< *SinglePred << "\n\n\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "To merge:\n"<< *
SinglePred << "\n\n\n"; } } while (false)
;
428 // Remember if SinglePred was the entry block of the function.
429 // If so, we will need to move BB back to the entry position.
430 bool isEntry = SinglePred == &SinglePred->getParent()->getEntryBlock();
431 MergeBasicBlockIntoOnlyPred(BB, nullptr);
432
433 if (isEntry && BB != &BB->getParent()->getEntryBlock())
434 BB->moveBefore(&BB->getParent()->getEntryBlock());
435
436 // We have erased a block. Update the iterator.
437 I = BB->getIterator();
438 }
439 }
440 return Changed;
441}
442
443/// Find a destination block from BB if BB is mergeable empty block.
444BasicBlock *CodeGenPrepare::findDestBlockOfMergeableEmptyBlock(BasicBlock *BB) {
445 // If this block doesn't end with an uncond branch, ignore it.
446 BranchInst *BI = dyn_cast<BranchInst>(BB->getTerminator());
447 if (!BI || !BI->isUnconditional())
448 return nullptr;
449
450 // If the instruction before the branch (skipping debug info) isn't a phi
451 // node, then other stuff is happening here.
452 BasicBlock::iterator BBI = BI->getIterator();
453 if (BBI != BB->begin()) {
454 --BBI;
455 while (isa<DbgInfoIntrinsic>(BBI)) {
456 if (BBI == BB->begin())
457 break;
458 --BBI;
459 }
460 if (!isa<DbgInfoIntrinsic>(BBI) && !isa<PHINode>(BBI))
461 return nullptr;
462 }
463
464 // Do not break infinite loops.
465 BasicBlock *DestBB = BI->getSuccessor(0);
466 if (DestBB == BB)
467 return nullptr;
468
469 if (!canMergeBlocks(BB, DestBB))
470 DestBB = nullptr;
471
472 return DestBB;
473}
474
475// Return the unique indirectbr predecessor of a block. This may return null
476// even if such a predecessor exists, if it's not useful for splitting.
477// If a predecessor is found, OtherPreds will contain all other (non-indirectbr)
478// predecessors of BB.
479static BasicBlock *
480findIBRPredecessor(BasicBlock *BB, SmallVectorImpl<BasicBlock *> &OtherPreds) {
481 // If the block doesn't have any PHIs, we don't care about it, since there's
482 // no point in splitting it.
483 PHINode *PN = dyn_cast<PHINode>(BB->begin());
484 if (!PN)
485 return nullptr;
486
487 // Verify we have exactly one IBR predecessor.
488 // Conservatively bail out if one of the other predecessors is not a "regular"
489 // terminator (that is, not a switch or a br).
490 BasicBlock *IBB = nullptr;
491 for (unsigned Pred = 0, E = PN->getNumIncomingValues(); Pred != E; ++Pred) {
492 BasicBlock *PredBB = PN->getIncomingBlock(Pred);
493 TerminatorInst *PredTerm = PredBB->getTerminator();
494 switch (PredTerm->getOpcode()) {
495 case Instruction::IndirectBr:
496 if (IBB)
497 return nullptr;
498 IBB = PredBB;
499 break;
500 case Instruction::Br:
501 case Instruction::Switch:
502 OtherPreds.push_back(PredBB);
503 continue;
504 default:
505 return nullptr;
506 }
507 }
508
509 return IBB;
510}
511
512// Split critical edges where the source of the edge is an indirectbr
513// instruction. This isn't always possible, but we can handle some easy cases.
514// This is useful because MI is unable to split such critical edges,
515// which means it will not be able to sink instructions along those edges.
516// This is especially painful for indirect branches with many successors, where
517// we end up having to prepare all outgoing values in the origin block.
518//
519// Our normal algorithm for splitting critical edges requires us to update
520// the outgoing edges of the edge origin block, but for an indirectbr this
521// is hard, since it would require finding and updating the block addresses
522// the indirect branch uses. But if a block only has a single indirectbr
523// predecessor, with the others being regular branches, we can do it in a
524// different way.
525// Say we have A -> D, B -> D, I -> D where only I -> D is an indirectbr.
526// We can split D into D0 and D1, where D0 contains only the PHIs from D,
527// and D1 is the D block body. We can then duplicate D0 as D0A and D0B, and
528// create the following structure:
529// A -> D0A, B -> D0A, I -> D0B, D0A -> D1, D0B -> D1
530bool CodeGenPrepare::splitIndirectCriticalEdges(Function &F) {
531 // Check whether the function has any indirectbrs, and collect which blocks
532 // they may jump to. Since most functions don't have indirect branches,
533 // this lowers the common case's overhead to O(Blocks) instead of O(Edges).
534 SmallSetVector<BasicBlock *, 16> Targets;
535 for (auto &BB : F) {
536 auto *IBI = dyn_cast<IndirectBrInst>(BB.getTerminator());
537 if (!IBI)
538 continue;
539
540 for (unsigned Succ = 0, E = IBI->getNumSuccessors(); Succ != E; ++Succ)
541 Targets.insert(IBI->getSuccessor(Succ));
542 }
543
544 if (Targets.empty())
545 return false;
546
547 bool Changed = false;
548 for (BasicBlock *Target : Targets) {
549 SmallVector<BasicBlock *, 16> OtherPreds;
550 BasicBlock *IBRPred = findIBRPredecessor(Target, OtherPreds);
551 // If we did not found an indirectbr, or the indirectbr is the only
552 // incoming edge, this isn't the kind of edge we're looking for.
553 if (!IBRPred || OtherPreds.empty())
554 continue;
555
556 // Don't even think about ehpads/landingpads.
557 Instruction *FirstNonPHI = Target->getFirstNonPHI();
558 if (FirstNonPHI->isEHPad() || Target->isLandingPad())
559 continue;
560
561 BasicBlock *BodyBlock = Target->splitBasicBlock(FirstNonPHI, ".split");
562 // It's possible Target was its own successor through an indirectbr.
563 // In this case, the indirectbr now comes from BodyBlock.
564 if (IBRPred == Target)
565 IBRPred = BodyBlock;
566
567 // At this point Target only has PHIs, and BodyBlock has the rest of the
568 // block's body. Create a copy of Target that will be used by the "direct"
569 // preds.
570 ValueToValueMapTy VMap;
571 BasicBlock *DirectSucc = CloneBasicBlock(Target, VMap, ".clone", &F);
572
573 for (BasicBlock *Pred : OtherPreds) {
574 // If the target is a loop to itself, then the terminator of the split
575 // block needs to be updated.
576 if (Pred == Target)
577 BodyBlock->getTerminator()->replaceUsesOfWith(Target, DirectSucc);
578 else
579 Pred->getTerminator()->replaceUsesOfWith(Target, DirectSucc);
580 }
581
582 // Ok, now fix up the PHIs. We know the two blocks only have PHIs, and that
583 // they are clones, so the number of PHIs are the same.
584 // (a) Remove the edge coming from IBRPred from the "Direct" PHI
585 // (b) Leave that as the only edge in the "Indirect" PHI.
586 // (c) Merge the two in the body block.
587 BasicBlock::iterator Indirect = Target->begin(),
588 End = Target->getFirstNonPHI()->getIterator();
589 BasicBlock::iterator Direct = DirectSucc->begin();
590 BasicBlock::iterator MergeInsert = BodyBlock->getFirstInsertionPt();
591
592 assert(&*End == Target->getTerminator() &&((&*End == Target->getTerminator() && "Block was expected to only contain PHIs"
) ? static_cast<void> (0) : __assert_fail ("&*End == Target->getTerminator() && \"Block was expected to only contain PHIs\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 593, __PRETTY_FUNCTION__))
593 "Block was expected to only contain PHIs")((&*End == Target->getTerminator() && "Block was expected to only contain PHIs"
) ? static_cast<void> (0) : __assert_fail ("&*End == Target->getTerminator() && \"Block was expected to only contain PHIs\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 593, __PRETTY_FUNCTION__))
;
594
595 while (Indirect != End) {
596 PHINode *DirPHI = cast<PHINode>(Direct);
597 PHINode *IndPHI = cast<PHINode>(Indirect);
598
599 // Now, clean up - the direct block shouldn't get the indirect value,
600 // and vice versa.
601 DirPHI->removeIncomingValue(IBRPred);
602 Direct++;
603
604 // Advance the pointer here, to avoid invalidation issues when the old
605 // PHI is erased.
606 Indirect++;
607
608 PHINode *NewIndPHI = PHINode::Create(IndPHI->getType(), 1, "ind", IndPHI);
609 NewIndPHI->addIncoming(IndPHI->getIncomingValueForBlock(IBRPred),
610 IBRPred);
611
612 // Create a PHI in the body block, to merge the direct and indirect
613 // predecessors.
614 PHINode *MergePHI =
615 PHINode::Create(IndPHI->getType(), 2, "merge", &*MergeInsert);
616 MergePHI->addIncoming(NewIndPHI, Target);
617 MergePHI->addIncoming(DirPHI, DirectSucc);
618
619 IndPHI->replaceAllUsesWith(MergePHI);
620 IndPHI->eraseFromParent();
621 }
622
623 Changed = true;
624 }
625
626 return Changed;
627}
628
629/// Eliminate blocks that contain only PHI nodes, debug info directives, and an
630/// unconditional branch. Passes before isel (e.g. LSR/loopsimplify) often split
631/// edges in ways that are non-optimal for isel. Start by eliminating these
632/// blocks so we can split them the way we want them.
633bool CodeGenPrepare::eliminateMostlyEmptyBlocks(Function &F) {
634 SmallPtrSet<BasicBlock *, 16> Preheaders;
635 SmallVector<Loop *, 16> LoopList(LI->begin(), LI->end());
636 while (!LoopList.empty()) {
637 Loop *L = LoopList.pop_back_val();
638 LoopList.insert(LoopList.end(), L->begin(), L->end());
639 if (BasicBlock *Preheader = L->getLoopPreheader())
640 Preheaders.insert(Preheader);
641 }
642
643 bool MadeChange = false;
644 // Note that this intentionally skips the entry block.
645 for (Function::iterator I = std::next(F.begin()), E = F.end(); I != E;) {
646 BasicBlock *BB = &*I++;
647 BasicBlock *DestBB = findDestBlockOfMergeableEmptyBlock(BB);
648 if (!DestBB ||
649 !isMergingEmptyBlockProfitable(BB, DestBB, Preheaders.count(BB)))
650 continue;
651
652 eliminateMostlyEmptyBlock(BB);
653 MadeChange = true;
654 }
655 return MadeChange;
656}
657
658bool CodeGenPrepare::isMergingEmptyBlockProfitable(BasicBlock *BB,
659 BasicBlock *DestBB,
660 bool isPreheader) {
661 // Do not delete loop preheaders if doing so would create a critical edge.
662 // Loop preheaders can be good locations to spill registers. If the
663 // preheader is deleted and we create a critical edge, registers may be
664 // spilled in the loop body instead.
665 if (!DisablePreheaderProtect && isPreheader &&
666 !(BB->getSinglePredecessor() &&
667 BB->getSinglePredecessor()->getSingleSuccessor()))
668 return false;
669
670 // Try to skip merging if the unique predecessor of BB is terminated by a
671 // switch or indirect branch instruction, and BB is used as an incoming block
672 // of PHIs in DestBB. In such case, merging BB and DestBB would cause ISel to
673 // add COPY instructions in the predecessor of BB instead of BB (if it is not
674 // merged). Note that the critical edge created by merging such blocks wont be
675 // split in MachineSink because the jump table is not analyzable. By keeping
676 // such empty block (BB), ISel will place COPY instructions in BB, not in the
677 // predecessor of BB.
678 BasicBlock *Pred = BB->getUniquePredecessor();
679 if (!Pred ||
680 !(isa<SwitchInst>(Pred->getTerminator()) ||
681 isa<IndirectBrInst>(Pred->getTerminator())))
682 return true;
683
684 if (BB->getTerminator() != BB->getFirstNonPHI())
685 return true;
686
687 // We use a simple cost heuristic which determine skipping merging is
688 // profitable if the cost of skipping merging is less than the cost of
689 // merging : Cost(skipping merging) < Cost(merging BB), where the
690 // Cost(skipping merging) is Freq(BB) * (Cost(Copy) + Cost(Branch)), and
691 // the Cost(merging BB) is Freq(Pred) * Cost(Copy).
692 // Assuming Cost(Copy) == Cost(Branch), we could simplify it to :
693 // Freq(Pred) / Freq(BB) > 2.
694 // Note that if there are multiple empty blocks sharing the same incoming
695 // value for the PHIs in the DestBB, we consider them together. In such
696 // case, Cost(merging BB) will be the sum of their frequencies.
697
698 if (!isa<PHINode>(DestBB->begin()))
699 return true;
700
701 SmallPtrSet<BasicBlock *, 16> SameIncomingValueBBs;
702
703 // Find all other incoming blocks from which incoming values of all PHIs in
704 // DestBB are the same as the ones from BB.
705 for (pred_iterator PI = pred_begin(DestBB), E = pred_end(DestBB); PI != E;
706 ++PI) {
707 BasicBlock *DestBBPred = *PI;
708 if (DestBBPred == BB)
709 continue;
710
711 bool HasAllSameValue = true;
712 BasicBlock::const_iterator DestBBI = DestBB->begin();
713 while (const PHINode *DestPN = dyn_cast<PHINode>(DestBBI++)) {
714 if (DestPN->getIncomingValueForBlock(BB) !=
715 DestPN->getIncomingValueForBlock(DestBBPred)) {
716 HasAllSameValue = false;
717 break;
718 }
719 }
720 if (HasAllSameValue)
721 SameIncomingValueBBs.insert(DestBBPred);
722 }
723
724 // See if all BB's incoming values are same as the value from Pred. In this
725 // case, no reason to skip merging because COPYs are expected to be place in
726 // Pred already.
727 if (SameIncomingValueBBs.count(Pred))
728 return true;
729
730 if (!BFI) {
731 Function &F = *BB->getParent();
732 LoopInfo LI{DominatorTree(F)};
733 BPI.reset(new BranchProbabilityInfo(F, LI));
734 BFI.reset(new BlockFrequencyInfo(F, *BPI, LI));
735 }
736
737 BlockFrequency PredFreq = BFI->getBlockFreq(Pred);
738 BlockFrequency BBFreq = BFI->getBlockFreq(BB);
739
740 for (auto SameValueBB : SameIncomingValueBBs)
741 if (SameValueBB->getUniquePredecessor() == Pred &&
742 DestBB == findDestBlockOfMergeableEmptyBlock(SameValueBB))
743 BBFreq += BFI->getBlockFreq(SameValueBB);
744
745 return PredFreq.getFrequency() <=
746 BBFreq.getFrequency() * FreqRatioToSkipMerge;
747}
748
749/// Return true if we can merge BB into DestBB if there is a single
750/// unconditional branch between them, and BB contains no other non-phi
751/// instructions.
752bool CodeGenPrepare::canMergeBlocks(const BasicBlock *BB,
753 const BasicBlock *DestBB) const {
754 // We only want to eliminate blocks whose phi nodes are used by phi nodes in
755 // the successor. If there are more complex condition (e.g. preheaders),
756 // don't mess around with them.
757 BasicBlock::const_iterator BBI = BB->begin();
758 while (const PHINode *PN = dyn_cast<PHINode>(BBI++)) {
759 for (const User *U : PN->users()) {
760 const Instruction *UI = cast<Instruction>(U);
761 if (UI->getParent() != DestBB || !isa<PHINode>(UI))
762 return false;
763 // If User is inside DestBB block and it is a PHINode then check
764 // incoming value. If incoming value is not from BB then this is
765 // a complex condition (e.g. preheaders) we want to avoid here.
766 if (UI->getParent() == DestBB) {
767 if (const PHINode *UPN = dyn_cast<PHINode>(UI))
768 for (unsigned I = 0, E = UPN->getNumIncomingValues(); I != E; ++I) {
769 Instruction *Insn = dyn_cast<Instruction>(UPN->getIncomingValue(I));
770 if (Insn && Insn->getParent() == BB &&
771 Insn->getParent() != UPN->getIncomingBlock(I))
772 return false;
773 }
774 }
775 }
776 }
777
778 // If BB and DestBB contain any common predecessors, then the phi nodes in BB
779 // and DestBB may have conflicting incoming values for the block. If so, we
780 // can't merge the block.
781 const PHINode *DestBBPN = dyn_cast<PHINode>(DestBB->begin());
782 if (!DestBBPN) return true; // no conflict.
783
784 // Collect the preds of BB.
785 SmallPtrSet<const BasicBlock*, 16> BBPreds;
786 if (const PHINode *BBPN = dyn_cast<PHINode>(BB->begin())) {
787 // It is faster to get preds from a PHI than with pred_iterator.
788 for (unsigned i = 0, e = BBPN->getNumIncomingValues(); i != e; ++i)
789 BBPreds.insert(BBPN->getIncomingBlock(i));
790 } else {
791 BBPreds.insert(pred_begin(BB), pred_end(BB));
792 }
793
794 // Walk the preds of DestBB.
795 for (unsigned i = 0, e = DestBBPN->getNumIncomingValues(); i != e; ++i) {
796 BasicBlock *Pred = DestBBPN->getIncomingBlock(i);
797 if (BBPreds.count(Pred)) { // Common predecessor?
798 BBI = DestBB->begin();
799 while (const PHINode *PN = dyn_cast<PHINode>(BBI++)) {
800 const Value *V1 = PN->getIncomingValueForBlock(Pred);
801 const Value *V2 = PN->getIncomingValueForBlock(BB);
802
803 // If V2 is a phi node in BB, look up what the mapped value will be.
804 if (const PHINode *V2PN = dyn_cast<PHINode>(V2))
805 if (V2PN->getParent() == BB)
806 V2 = V2PN->getIncomingValueForBlock(Pred);
807
808 // If there is a conflict, bail out.
809 if (V1 != V2) return false;
810 }
811 }
812 }
813
814 return true;
815}
816
817
818/// Eliminate a basic block that has only phi's and an unconditional branch in
819/// it.
820void CodeGenPrepare::eliminateMostlyEmptyBlock(BasicBlock *BB) {
821 BranchInst *BI = cast<BranchInst>(BB->getTerminator());
822 BasicBlock *DestBB = BI->getSuccessor(0);
823
824 DEBUG(dbgs() << "MERGING MOSTLY EMPTY BLOCKS - BEFORE:\n" << *BB << *DestBB)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "MERGING MOSTLY EMPTY BLOCKS - BEFORE:\n"
<< *BB << *DestBB; } } while (false)
;
825
826 // If the destination block has a single pred, then this is a trivial edge,
827 // just collapse it.
828 if (BasicBlock *SinglePred = DestBB->getSinglePredecessor()) {
829 if (SinglePred != DestBB) {
830 // Remember if SinglePred was the entry block of the function. If so, we
831 // will need to move BB back to the entry position.
832 bool isEntry = SinglePred == &SinglePred->getParent()->getEntryBlock();
833 MergeBasicBlockIntoOnlyPred(DestBB, nullptr);
834
835 if (isEntry && BB != &BB->getParent()->getEntryBlock())
836 BB->moveBefore(&BB->getParent()->getEntryBlock());
837
838 DEBUG(dbgs() << "AFTER:\n" << *DestBB << "\n\n\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "AFTER:\n" << *DestBB
<< "\n\n\n"; } } while (false)
;
839 return;
840 }
841 }
842
843 // Otherwise, we have multiple predecessors of BB. Update the PHIs in DestBB
844 // to handle the new incoming edges it is about to have.
845 PHINode *PN;
846 for (BasicBlock::iterator BBI = DestBB->begin();
847 (PN = dyn_cast<PHINode>(BBI)); ++BBI) {
848 // Remove the incoming value for BB, and remember it.
849 Value *InVal = PN->removeIncomingValue(BB, false);
850
851 // Two options: either the InVal is a phi node defined in BB or it is some
852 // value that dominates BB.
853 PHINode *InValPhi = dyn_cast<PHINode>(InVal);
854 if (InValPhi && InValPhi->getParent() == BB) {
855 // Add all of the input values of the input PHI as inputs of this phi.
856 for (unsigned i = 0, e = InValPhi->getNumIncomingValues(); i != e; ++i)
857 PN->addIncoming(InValPhi->getIncomingValue(i),
858 InValPhi->getIncomingBlock(i));
859 } else {
860 // Otherwise, add one instance of the dominating value for each edge that
861 // we will be adding.
862 if (PHINode *BBPN = dyn_cast<PHINode>(BB->begin())) {
863 for (unsigned i = 0, e = BBPN->getNumIncomingValues(); i != e; ++i)
864 PN->addIncoming(InVal, BBPN->getIncomingBlock(i));
865 } else {
866 for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI)
867 PN->addIncoming(InVal, *PI);
868 }
869 }
870 }
871
872 // The PHIs are now updated, change everything that refers to BB to use
873 // DestBB and remove BB.
874 BB->replaceAllUsesWith(DestBB);
875 BB->eraseFromParent();
876 ++NumBlocksElim;
877
878 DEBUG(dbgs() << "AFTER:\n" << *DestBB << "\n\n\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "AFTER:\n" << *DestBB
<< "\n\n\n"; } } while (false)
;
879}
880
881// Computes a map of base pointer relocation instructions to corresponding
882// derived pointer relocation instructions given a vector of all relocate calls
883static void computeBaseDerivedRelocateMap(
884 const SmallVectorImpl<GCRelocateInst *> &AllRelocateCalls,
885 DenseMap<GCRelocateInst *, SmallVector<GCRelocateInst *, 2>>
886 &RelocateInstMap) {
887 // Collect information in two maps: one primarily for locating the base object
888 // while filling the second map; the second map is the final structure holding
889 // a mapping between Base and corresponding Derived relocate calls
890 DenseMap<std::pair<unsigned, unsigned>, GCRelocateInst *> RelocateIdxMap;
891 for (auto *ThisRelocate : AllRelocateCalls) {
892 auto K = std::make_pair(ThisRelocate->getBasePtrIndex(),
893 ThisRelocate->getDerivedPtrIndex());
894 RelocateIdxMap.insert(std::make_pair(K, ThisRelocate));
895 }
896 for (auto &Item : RelocateIdxMap) {
897 std::pair<unsigned, unsigned> Key = Item.first;
898 if (Key.first == Key.second)
899 // Base relocation: nothing to insert
900 continue;
901
902 GCRelocateInst *I = Item.second;
903 auto BaseKey = std::make_pair(Key.first, Key.first);
904
905 // We're iterating over RelocateIdxMap so we cannot modify it.
906 auto MaybeBase = RelocateIdxMap.find(BaseKey);
907 if (MaybeBase == RelocateIdxMap.end())
908 // TODO: We might want to insert a new base object relocate and gep off
909 // that, if there are enough derived object relocates.
910 continue;
911
912 RelocateInstMap[MaybeBase->second].push_back(I);
913 }
914}
915
916// Accepts a GEP and extracts the operands into a vector provided they're all
917// small integer constants
918static bool getGEPSmallConstantIntOffsetV(GetElementPtrInst *GEP,
919 SmallVectorImpl<Value *> &OffsetV) {
920 for (unsigned i = 1; i < GEP->getNumOperands(); i++) {
921 // Only accept small constant integer operands
922 auto Op = dyn_cast<ConstantInt>(GEP->getOperand(i));
923 if (!Op || Op->getZExtValue() > 20)
924 return false;
925 }
926
927 for (unsigned i = 1; i < GEP->getNumOperands(); i++)
928 OffsetV.push_back(GEP->getOperand(i));
929 return true;
930}
931
932// Takes a RelocatedBase (base pointer relocation instruction) and Targets to
933// replace, computes a replacement, and affects it.
934static bool
935simplifyRelocatesOffABase(GCRelocateInst *RelocatedBase,
936 const SmallVectorImpl<GCRelocateInst *> &Targets) {
937 bool MadeChange = false;
938 for (GCRelocateInst *ToReplace : Targets) {
939 assert(ToReplace->getBasePtrIndex() == RelocatedBase->getBasePtrIndex() &&((ToReplace->getBasePtrIndex() == RelocatedBase->getBasePtrIndex
() && "Not relocating a derived object of the original base object"
) ? static_cast<void> (0) : __assert_fail ("ToReplace->getBasePtrIndex() == RelocatedBase->getBasePtrIndex() && \"Not relocating a derived object of the original base object\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 940, __PRETTY_FUNCTION__))
940 "Not relocating a derived object of the original base object")((ToReplace->getBasePtrIndex() == RelocatedBase->getBasePtrIndex
() && "Not relocating a derived object of the original base object"
) ? static_cast<void> (0) : __assert_fail ("ToReplace->getBasePtrIndex() == RelocatedBase->getBasePtrIndex() && \"Not relocating a derived object of the original base object\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 940, __PRETTY_FUNCTION__))
;
941 if (ToReplace->getBasePtrIndex() == ToReplace->getDerivedPtrIndex()) {
942 // A duplicate relocate call. TODO: coalesce duplicates.
943 continue;
944 }
945
946 if (RelocatedBase->getParent() != ToReplace->getParent()) {
947 // Base and derived relocates are in different basic blocks.
948 // In this case transform is only valid when base dominates derived
949 // relocate. However it would be too expensive to check dominance
950 // for each such relocate, so we skip the whole transformation.
951 continue;
952 }
953
954 Value *Base = ToReplace->getBasePtr();
955 auto Derived = dyn_cast<GetElementPtrInst>(ToReplace->getDerivedPtr());
956 if (!Derived || Derived->getPointerOperand() != Base)
957 continue;
958
959 SmallVector<Value *, 2> OffsetV;
960 if (!getGEPSmallConstantIntOffsetV(Derived, OffsetV))
961 continue;
962
963 // Create a Builder and replace the target callsite with a gep
964 assert(RelocatedBase->getNextNode() &&((RelocatedBase->getNextNode() && "Should always have one since it's not a terminator"
) ? static_cast<void> (0) : __assert_fail ("RelocatedBase->getNextNode() && \"Should always have one since it's not a terminator\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 965, __PRETTY_FUNCTION__))
965 "Should always have one since it's not a terminator")((RelocatedBase->getNextNode() && "Should always have one since it's not a terminator"
) ? static_cast<void> (0) : __assert_fail ("RelocatedBase->getNextNode() && \"Should always have one since it's not a terminator\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 965, __PRETTY_FUNCTION__))
;
966
967 // Insert after RelocatedBase
968 IRBuilder<> Builder(RelocatedBase->getNextNode());
969 Builder.SetCurrentDebugLocation(ToReplace->getDebugLoc());
970
971 // If gc_relocate does not match the actual type, cast it to the right type.
972 // In theory, there must be a bitcast after gc_relocate if the type does not
973 // match, and we should reuse it to get the derived pointer. But it could be
974 // cases like this:
975 // bb1:
976 // ...
977 // %g1 = call coldcc i8 addrspace(1)* @llvm.experimental.gc.relocate.p1i8(...)
978 // br label %merge
979 //
980 // bb2:
981 // ...
982 // %g2 = call coldcc i8 addrspace(1)* @llvm.experimental.gc.relocate.p1i8(...)
983 // br label %merge
984 //
985 // merge:
986 // %p1 = phi i8 addrspace(1)* [ %g1, %bb1 ], [ %g2, %bb2 ]
987 // %cast = bitcast i8 addrspace(1)* %p1 in to i32 addrspace(1)*
988 //
989 // In this case, we can not find the bitcast any more. So we insert a new bitcast
990 // no matter there is already one or not. In this way, we can handle all cases, and
991 // the extra bitcast should be optimized away in later passes.
992 Value *ActualRelocatedBase = RelocatedBase;
993 if (RelocatedBase->getType() != Base->getType()) {
994 ActualRelocatedBase =
995 Builder.CreateBitCast(RelocatedBase, Base->getType());
996 }
997 Value *Replacement = Builder.CreateGEP(
998 Derived->getSourceElementType(), ActualRelocatedBase, makeArrayRef(OffsetV));
999 Replacement->takeName(ToReplace);
1000 // If the newly generated derived pointer's type does not match the original derived
1001 // pointer's type, cast the new derived pointer to match it. Same reasoning as above.
1002 Value *ActualReplacement = Replacement;
1003 if (Replacement->getType() != ToReplace->getType()) {
1004 ActualReplacement =
1005 Builder.CreateBitCast(Replacement, ToReplace->getType());
1006 }
1007 ToReplace->replaceAllUsesWith(ActualReplacement);
1008 ToReplace->eraseFromParent();
1009
1010 MadeChange = true;
1011 }
1012 return MadeChange;
1013}
1014
1015// Turns this:
1016//
1017// %base = ...
1018// %ptr = gep %base + 15
1019// %tok = statepoint (%fun, i32 0, i32 0, i32 0, %base, %ptr)
1020// %base' = relocate(%tok, i32 4, i32 4)
1021// %ptr' = relocate(%tok, i32 4, i32 5)
1022// %val = load %ptr'
1023//
1024// into this:
1025//
1026// %base = ...
1027// %ptr = gep %base + 15
1028// %tok = statepoint (%fun, i32 0, i32 0, i32 0, %base, %ptr)
1029// %base' = gc.relocate(%tok, i32 4, i32 4)
1030// %ptr' = gep %base' + 15
1031// %val = load %ptr'
1032bool CodeGenPrepare::simplifyOffsetableRelocate(Instruction &I) {
1033 bool MadeChange = false;
1034 SmallVector<GCRelocateInst *, 2> AllRelocateCalls;
1035
1036 for (auto *U : I.users())
1037 if (GCRelocateInst *Relocate = dyn_cast<GCRelocateInst>(U))
1038 // Collect all the relocate calls associated with a statepoint
1039 AllRelocateCalls.push_back(Relocate);
1040
1041 // We need atleast one base pointer relocation + one derived pointer
1042 // relocation to mangle
1043 if (AllRelocateCalls.size() < 2)
1044 return false;
1045
1046 // RelocateInstMap is a mapping from the base relocate instruction to the
1047 // corresponding derived relocate instructions
1048 DenseMap<GCRelocateInst *, SmallVector<GCRelocateInst *, 2>> RelocateInstMap;
1049 computeBaseDerivedRelocateMap(AllRelocateCalls, RelocateInstMap);
1050 if (RelocateInstMap.empty())
1051 return false;
1052
1053 for (auto &Item : RelocateInstMap)
1054 // Item.first is the RelocatedBase to offset against
1055 // Item.second is the vector of Targets to replace
1056 MadeChange = simplifyRelocatesOffABase(Item.first, Item.second);
1057 return MadeChange;
1058}
1059
1060/// SinkCast - Sink the specified cast instruction into its user blocks
1061static bool SinkCast(CastInst *CI) {
1062 BasicBlock *DefBB = CI->getParent();
1063
1064 /// InsertedCasts - Only insert a cast in each block once.
1065 DenseMap<BasicBlock*, CastInst*> InsertedCasts;
1066
1067 bool MadeChange = false;
1068 for (Value::user_iterator UI = CI->user_begin(), E = CI->user_end();
1069 UI != E; ) {
1070 Use &TheUse = UI.getUse();
1071 Instruction *User = cast<Instruction>(*UI);
1072
1073 // Figure out which BB this cast is used in. For PHI's this is the
1074 // appropriate predecessor block.
1075 BasicBlock *UserBB = User->getParent();
1076 if (PHINode *PN = dyn_cast<PHINode>(User)) {
1077 UserBB = PN->getIncomingBlock(TheUse);
1078 }
1079
1080 // Preincrement use iterator so we don't invalidate it.
1081 ++UI;
1082
1083 // The first insertion point of a block containing an EH pad is after the
1084 // pad. If the pad is the user, we cannot sink the cast past the pad.
1085 if (User->isEHPad())
1086 continue;
1087
1088 // If the block selected to receive the cast is an EH pad that does not
1089 // allow non-PHI instructions before the terminator, we can't sink the
1090 // cast.
1091 if (UserBB->getTerminator()->isEHPad())
1092 continue;
1093
1094 // If this user is in the same block as the cast, don't change the cast.
1095 if (UserBB == DefBB) continue;
1096
1097 // If we have already inserted a cast into this block, use it.
1098 CastInst *&InsertedCast = InsertedCasts[UserBB];
1099
1100 if (!InsertedCast) {
1101 BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
1102 assert(InsertPt != UserBB->end())((InsertPt != UserBB->end()) ? static_cast<void> (0)
: __assert_fail ("InsertPt != UserBB->end()", "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 1102, __PRETTY_FUNCTION__))
;
1103 InsertedCast = CastInst::Create(CI->getOpcode(), CI->getOperand(0),
1104 CI->getType(), "", &*InsertPt);
1105 }
1106
1107 // Replace a use of the cast with a use of the new cast.
1108 TheUse = InsertedCast;
1109 MadeChange = true;
1110 ++NumCastUses;
1111 }
1112
1113 // If we removed all uses, nuke the cast.
1114 if (CI->use_empty()) {
1115 CI->eraseFromParent();
1116 MadeChange = true;
1117 }
1118
1119 return MadeChange;
1120}
1121
1122/// If the specified cast instruction is a noop copy (e.g. it's casting from
1123/// one pointer type to another, i32->i8 on PPC), sink it into user blocks to
1124/// reduce the number of virtual registers that must be created and coalesced.
1125///
1126/// Return true if any changes are made.
1127///
1128static bool OptimizeNoopCopyExpression(CastInst *CI, const TargetLowering &TLI,
1129 const DataLayout &DL) {
1130 // Sink only "cheap" (or nop) address-space casts. This is a weaker condition
1131 // than sinking only nop casts, but is helpful on some platforms.
1132 if (auto *ASC = dyn_cast<AddrSpaceCastInst>(CI)) {
1133 if (!TLI.isCheapAddrSpaceCast(ASC->getSrcAddressSpace(),
1134 ASC->getDestAddressSpace()))
1135 return false;
1136 }
1137
1138 // If this is a noop copy,
1139 EVT SrcVT = TLI.getValueType(DL, CI->getOperand(0)->getType());
1140 EVT DstVT = TLI.getValueType(DL, CI->getType());
1141
1142 // This is an fp<->int conversion?
1143 if (SrcVT.isInteger() != DstVT.isInteger())
1144 return false;
1145
1146 // If this is an extension, it will be a zero or sign extension, which
1147 // isn't a noop.
1148 if (SrcVT.bitsLT(DstVT)) return false;
1149
1150 // If these values will be promoted, find out what they will be promoted
1151 // to. This helps us consider truncates on PPC as noop copies when they
1152 // are.
1153 if (TLI.getTypeAction(CI->getContext(), SrcVT) ==
1154 TargetLowering::TypePromoteInteger)
1155 SrcVT = TLI.getTypeToTransformTo(CI->getContext(), SrcVT);
1156 if (TLI.getTypeAction(CI->getContext(), DstVT) ==
1157 TargetLowering::TypePromoteInteger)
1158 DstVT = TLI.getTypeToTransformTo(CI->getContext(), DstVT);
1159
1160 // If, after promotion, these are the same types, this is a noop copy.
1161 if (SrcVT != DstVT)
1162 return false;
1163
1164 return SinkCast(CI);
1165}
1166
1167/// Try to combine CI into a call to the llvm.uadd.with.overflow intrinsic if
1168/// possible.
1169///
1170/// Return true if any changes were made.
1171static bool CombineUAddWithOverflow(CmpInst *CI) {
1172 Value *A, *B;
1173 Instruction *AddI;
1174 if (!match(CI,
1175 m_UAddWithOverflow(m_Value(A), m_Value(B), m_Instruction(AddI))))
1176 return false;
1177
1178 Type *Ty = AddI->getType();
1179 if (!isa<IntegerType>(Ty))
1180 return false;
1181
1182 // We don't want to move around uses of condition values this late, so we we
1183 // check if it is legal to create the call to the intrinsic in the basic
1184 // block containing the icmp:
1185
1186 if (AddI->getParent() != CI->getParent() && !AddI->hasOneUse())
1187 return false;
1188
1189#ifndef NDEBUG
1190 // Someday m_UAddWithOverflow may get smarter, but this is a safe assumption
1191 // for now:
1192 if (AddI->hasOneUse())
1193 assert(*AddI->user_begin() == CI && "expected!")((*AddI->user_begin() == CI && "expected!") ? static_cast
<void> (0) : __assert_fail ("*AddI->user_begin() == CI && \"expected!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 1193, __PRETTY_FUNCTION__))
;
1194#endif
1195
1196 Module *M = CI->getModule();
1197 Value *F = Intrinsic::getDeclaration(M, Intrinsic::uadd_with_overflow, Ty);
1198
1199 auto *InsertPt = AddI->hasOneUse() ? CI : AddI;
1200
1201 auto *UAddWithOverflow =
1202 CallInst::Create(F, {A, B}, "uadd.overflow", InsertPt);
1203 auto *UAdd = ExtractValueInst::Create(UAddWithOverflow, 0, "uadd", InsertPt);
1204 auto *Overflow =
1205 ExtractValueInst::Create(UAddWithOverflow, 1, "overflow", InsertPt);
1206
1207 CI->replaceAllUsesWith(Overflow);
1208 AddI->replaceAllUsesWith(UAdd);
1209 CI->eraseFromParent();
1210 AddI->eraseFromParent();
1211 return true;
1212}
1213
1214/// Sink the given CmpInst into user blocks to reduce the number of virtual
1215/// registers that must be created and coalesced. This is a clear win except on
1216/// targets with multiple condition code registers (PowerPC), where it might
1217/// lose; some adjustment may be wanted there.
1218///
1219/// Return true if any changes are made.
1220static bool SinkCmpExpression(CmpInst *CI, const TargetLowering *TLI) {
1221 BasicBlock *DefBB = CI->getParent();
1222
1223 // Avoid sinking soft-FP comparisons, since this can move them into a loop.
1224 if (TLI && TLI->useSoftFloat() && isa<FCmpInst>(CI))
1225 return false;
1226
1227 // Only insert a cmp in each block once.
1228 DenseMap<BasicBlock*, CmpInst*> InsertedCmps;
1229
1230 bool MadeChange = false;
1231 for (Value::user_iterator UI = CI->user_begin(), E = CI->user_end();
1232 UI != E; ) {
1233 Use &TheUse = UI.getUse();
1234 Instruction *User = cast<Instruction>(*UI);
1235
1236 // Preincrement use iterator so we don't invalidate it.
1237 ++UI;
1238
1239 // Don't bother for PHI nodes.
1240 if (isa<PHINode>(User))
1241 continue;
1242
1243 // Figure out which BB this cmp is used in.
1244 BasicBlock *UserBB = User->getParent();
1245
1246 // If this user is in the same block as the cmp, don't change the cmp.
1247 if (UserBB == DefBB) continue;
1248
1249 // If we have already inserted a cmp into this block, use it.
1250 CmpInst *&InsertedCmp = InsertedCmps[UserBB];
1251
1252 if (!InsertedCmp) {
1253 BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
1254 assert(InsertPt != UserBB->end())((InsertPt != UserBB->end()) ? static_cast<void> (0)
: __assert_fail ("InsertPt != UserBB->end()", "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 1254, __PRETTY_FUNCTION__))
;
1255 InsertedCmp =
1256 CmpInst::Create(CI->getOpcode(), CI->getPredicate(),
1257 CI->getOperand(0), CI->getOperand(1), "", &*InsertPt);
1258 // Propagate the debug info.
1259 InsertedCmp->setDebugLoc(CI->getDebugLoc());
1260 }
1261
1262 // Replace a use of the cmp with a use of the new cmp.
1263 TheUse = InsertedCmp;
1264 MadeChange = true;
1265 ++NumCmpUses;
1266 }
1267
1268 // If we removed all uses, nuke the cmp.
1269 if (CI->use_empty()) {
1270 CI->eraseFromParent();
1271 MadeChange = true;
1272 }
1273
1274 return MadeChange;
1275}
1276
1277static bool OptimizeCmpExpression(CmpInst *CI, const TargetLowering *TLI) {
1278 if (SinkCmpExpression(CI, TLI))
1279 return true;
1280
1281 if (CombineUAddWithOverflow(CI))
1282 return true;
1283
1284 return false;
1285}
1286
1287/// Duplicate and sink the given 'and' instruction into user blocks where it is
1288/// used in a compare to allow isel to generate better code for targets where
1289/// this operation can be combined.
1290///
1291/// Return true if any changes are made.
1292static bool sinkAndCmp0Expression(Instruction *AndI,
1293 const TargetLowering &TLI,
1294 SetOfInstrs &InsertedInsts) {
1295 // Double-check that we're not trying to optimize an instruction that was
1296 // already optimized by some other part of this pass.
1297 assert(!InsertedInsts.count(AndI) &&((!InsertedInsts.count(AndI) && "Attempting to optimize already optimized and instruction"
) ? static_cast<void> (0) : __assert_fail ("!InsertedInsts.count(AndI) && \"Attempting to optimize already optimized and instruction\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 1298, __PRETTY_FUNCTION__))
1298 "Attempting to optimize already optimized and instruction")((!InsertedInsts.count(AndI) && "Attempting to optimize already optimized and instruction"
) ? static_cast<void> (0) : __assert_fail ("!InsertedInsts.count(AndI) && \"Attempting to optimize already optimized and instruction\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 1298, __PRETTY_FUNCTION__))
;
1299 (void) InsertedInsts;
1300
1301 // Nothing to do for single use in same basic block.
1302 if (AndI->hasOneUse() &&
1303 AndI->getParent() == cast<Instruction>(*AndI->user_begin())->getParent())
1304 return false;
1305
1306 // Try to avoid cases where sinking/duplicating is likely to increase register
1307 // pressure.
1308 if (!isa<ConstantInt>(AndI->getOperand(0)) &&
1309 !isa<ConstantInt>(AndI->getOperand(1)) &&
1310 AndI->getOperand(0)->hasOneUse() && AndI->getOperand(1)->hasOneUse())
1311 return false;
1312
1313 for (auto *U : AndI->users()) {
1314 Instruction *User = cast<Instruction>(U);
1315
1316 // Only sink for and mask feeding icmp with 0.
1317 if (!isa<ICmpInst>(User))
1318 return false;
1319
1320 auto *CmpC = dyn_cast<ConstantInt>(User->getOperand(1));
1321 if (!CmpC || !CmpC->isZero())
1322 return false;
1323 }
1324
1325 if (!TLI.isMaskAndCmp0FoldingBeneficial(*AndI))
1326 return false;
1327
1328 DEBUG(dbgs() << "found 'and' feeding only icmp 0;\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "found 'and' feeding only icmp 0;\n"
; } } while (false)
;
1329 DEBUG(AndI->getParent()->dump())do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { AndI->getParent()->dump(); } } while
(false)
;
1330
1331 // Push the 'and' into the same block as the icmp 0. There should only be
1332 // one (icmp (and, 0)) in each block, since CSE/GVN should have removed any
1333 // others, so we don't need to keep track of which BBs we insert into.
1334 for (Value::user_iterator UI = AndI->user_begin(), E = AndI->user_end();
1335 UI != E; ) {
1336 Use &TheUse = UI.getUse();
1337 Instruction *User = cast<Instruction>(*UI);
1338
1339 // Preincrement use iterator so we don't invalidate it.
1340 ++UI;
1341
1342 DEBUG(dbgs() << "sinking 'and' use: " << *User << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "sinking 'and' use: " <<
*User << "\n"; } } while (false)
;
1343
1344 // Keep the 'and' in the same place if the use is already in the same block.
1345 Instruction *InsertPt =
1346 User->getParent() == AndI->getParent() ? AndI : User;
1347 Instruction *InsertedAnd =
1348 BinaryOperator::Create(Instruction::And, AndI->getOperand(0),
1349 AndI->getOperand(1), "", InsertPt);
1350 // Propagate the debug info.
1351 InsertedAnd->setDebugLoc(AndI->getDebugLoc());
1352
1353 // Replace a use of the 'and' with a use of the new 'and'.
1354 TheUse = InsertedAnd;
1355 ++NumAndUses;
1356 DEBUG(User->getParent()->dump())do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { User->getParent()->dump(); } } while
(false)
;
1357 }
1358
1359 // We removed all uses, nuke the and.
1360 AndI->eraseFromParent();
1361 return true;
1362}
1363
1364/// Check if the candidates could be combined with a shift instruction, which
1365/// includes:
1366/// 1. Truncate instruction
1367/// 2. And instruction and the imm is a mask of the low bits:
1368/// imm & (imm+1) == 0
1369static bool isExtractBitsCandidateUse(Instruction *User) {
1370 if (!isa<TruncInst>(User)) {
1371 if (User->getOpcode() != Instruction::And ||
1372 !isa<ConstantInt>(User->getOperand(1)))
1373 return false;
1374
1375 const APInt &Cimm = cast<ConstantInt>(User->getOperand(1))->getValue();
1376
1377 if ((Cimm & (Cimm + 1)).getBoolValue())
1378 return false;
1379 }
1380 return true;
1381}
1382
1383/// Sink both shift and truncate instruction to the use of truncate's BB.
1384static bool
1385SinkShiftAndTruncate(BinaryOperator *ShiftI, Instruction *User, ConstantInt *CI,
1386 DenseMap<BasicBlock *, BinaryOperator *> &InsertedShifts,
1387 const TargetLowering &TLI, const DataLayout &DL) {
1388 BasicBlock *UserBB = User->getParent();
1389 DenseMap<BasicBlock *, CastInst *> InsertedTruncs;
1390 TruncInst *TruncI = dyn_cast<TruncInst>(User);
1391 bool MadeChange = false;
1392
1393 for (Value::user_iterator TruncUI = TruncI->user_begin(),
1394 TruncE = TruncI->user_end();
1395 TruncUI != TruncE;) {
1396
1397 Use &TruncTheUse = TruncUI.getUse();
1398 Instruction *TruncUser = cast<Instruction>(*TruncUI);
1399 // Preincrement use iterator so we don't invalidate it.
1400
1401 ++TruncUI;
1402
1403 int ISDOpcode = TLI.InstructionOpcodeToISD(TruncUser->getOpcode());
1404 if (!ISDOpcode)
1405 continue;
1406
1407 // If the use is actually a legal node, there will not be an
1408 // implicit truncate.
1409 // FIXME: always querying the result type is just an
1410 // approximation; some nodes' legality is determined by the
1411 // operand or other means. There's no good way to find out though.
1412 if (TLI.isOperationLegalOrCustom(
1413 ISDOpcode, TLI.getValueType(DL, TruncUser->getType(), true)))
1414 continue;
1415
1416 // Don't bother for PHI nodes.
1417 if (isa<PHINode>(TruncUser))
1418 continue;
1419
1420 BasicBlock *TruncUserBB = TruncUser->getParent();
1421
1422 if (UserBB == TruncUserBB)
1423 continue;
1424
1425 BinaryOperator *&InsertedShift = InsertedShifts[TruncUserBB];
1426 CastInst *&InsertedTrunc = InsertedTruncs[TruncUserBB];
1427
1428 if (!InsertedShift && !InsertedTrunc) {
1429 BasicBlock::iterator InsertPt = TruncUserBB->getFirstInsertionPt();
1430 assert(InsertPt != TruncUserBB->end())((InsertPt != TruncUserBB->end()) ? static_cast<void>
(0) : __assert_fail ("InsertPt != TruncUserBB->end()", "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 1430, __PRETTY_FUNCTION__))
;
1431 // Sink the shift
1432 if (ShiftI->getOpcode() == Instruction::AShr)
1433 InsertedShift = BinaryOperator::CreateAShr(ShiftI->getOperand(0), CI,
1434 "", &*InsertPt);
1435 else
1436 InsertedShift = BinaryOperator::CreateLShr(ShiftI->getOperand(0), CI,
1437 "", &*InsertPt);
1438
1439 // Sink the trunc
1440 BasicBlock::iterator TruncInsertPt = TruncUserBB->getFirstInsertionPt();
1441 TruncInsertPt++;
1442 assert(TruncInsertPt != TruncUserBB->end())((TruncInsertPt != TruncUserBB->end()) ? static_cast<void
> (0) : __assert_fail ("TruncInsertPt != TruncUserBB->end()"
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 1442, __PRETTY_FUNCTION__))
;
1443
1444 InsertedTrunc = CastInst::Create(TruncI->getOpcode(), InsertedShift,
1445 TruncI->getType(), "", &*TruncInsertPt);
1446
1447 MadeChange = true;
1448
1449 TruncTheUse = InsertedTrunc;
1450 }
1451 }
1452 return MadeChange;
1453}
1454
1455/// Sink the shift *right* instruction into user blocks if the uses could
1456/// potentially be combined with this shift instruction and generate BitExtract
1457/// instruction. It will only be applied if the architecture supports BitExtract
1458/// instruction. Here is an example:
1459/// BB1:
1460/// %x.extract.shift = lshr i64 %arg1, 32
1461/// BB2:
1462/// %x.extract.trunc = trunc i64 %x.extract.shift to i16
1463/// ==>
1464///
1465/// BB2:
1466/// %x.extract.shift.1 = lshr i64 %arg1, 32
1467/// %x.extract.trunc = trunc i64 %x.extract.shift.1 to i16
1468///
1469/// CodeGen will recoginze the pattern in BB2 and generate BitExtract
1470/// instruction.
1471/// Return true if any changes are made.
1472static bool OptimizeExtractBits(BinaryOperator *ShiftI, ConstantInt *CI,
1473 const TargetLowering &TLI,
1474 const DataLayout &DL) {
1475 BasicBlock *DefBB = ShiftI->getParent();
1476
1477 /// Only insert instructions in each block once.
1478 DenseMap<BasicBlock *, BinaryOperator *> InsertedShifts;
1479
1480 bool shiftIsLegal = TLI.isTypeLegal(TLI.getValueType(DL, ShiftI->getType()));
1481
1482 bool MadeChange = false;
1483 for (Value::user_iterator UI = ShiftI->user_begin(), E = ShiftI->user_end();
1484 UI != E;) {
1485 Use &TheUse = UI.getUse();
1486 Instruction *User = cast<Instruction>(*UI);
1487 // Preincrement use iterator so we don't invalidate it.
1488 ++UI;
1489
1490 // Don't bother for PHI nodes.
1491 if (isa<PHINode>(User))
1492 continue;
1493
1494 if (!isExtractBitsCandidateUse(User))
1495 continue;
1496
1497 BasicBlock *UserBB = User->getParent();
1498
1499 if (UserBB == DefBB) {
1500 // If the shift and truncate instruction are in the same BB. The use of
1501 // the truncate(TruncUse) may still introduce another truncate if not
1502 // legal. In this case, we would like to sink both shift and truncate
1503 // instruction to the BB of TruncUse.
1504 // for example:
1505 // BB1:
1506 // i64 shift.result = lshr i64 opnd, imm
1507 // trunc.result = trunc shift.result to i16
1508 //
1509 // BB2:
1510 // ----> We will have an implicit truncate here if the architecture does
1511 // not have i16 compare.
1512 // cmp i16 trunc.result, opnd2
1513 //
1514 if (isa<TruncInst>(User) && shiftIsLegal
1515 // If the type of the truncate is legal, no trucate will be
1516 // introduced in other basic blocks.
1517 &&
1518 (!TLI.isTypeLegal(TLI.getValueType(DL, User->getType()))))
1519 MadeChange =
1520 SinkShiftAndTruncate(ShiftI, User, CI, InsertedShifts, TLI, DL);
1521
1522 continue;
1523 }
1524 // If we have already inserted a shift into this block, use it.
1525 BinaryOperator *&InsertedShift = InsertedShifts[UserBB];
1526
1527 if (!InsertedShift) {
1528 BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
1529 assert(InsertPt != UserBB->end())((InsertPt != UserBB->end()) ? static_cast<void> (0)
: __assert_fail ("InsertPt != UserBB->end()", "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 1529, __PRETTY_FUNCTION__))
;
1530
1531 if (ShiftI->getOpcode() == Instruction::AShr)
1532 InsertedShift = BinaryOperator::CreateAShr(ShiftI->getOperand(0), CI,
1533 "", &*InsertPt);
1534 else
1535 InsertedShift = BinaryOperator::CreateLShr(ShiftI->getOperand(0), CI,
1536 "", &*InsertPt);
1537
1538 MadeChange = true;
1539 }
1540
1541 // Replace a use of the shift with a use of the new shift.
1542 TheUse = InsertedShift;
1543 }
1544
1545 // If we removed all uses, nuke the shift.
1546 if (ShiftI->use_empty())
1547 ShiftI->eraseFromParent();
1548
1549 return MadeChange;
1550}
1551
1552// Translate a masked load intrinsic like
1553// <16 x i32 > @llvm.masked.load( <16 x i32>* %addr, i32 align,
1554// <16 x i1> %mask, <16 x i32> %passthru)
1555// to a chain of basic blocks, with loading element one-by-one if
1556// the appropriate mask bit is set
1557//
1558// %1 = bitcast i8* %addr to i32*
1559// %2 = extractelement <16 x i1> %mask, i32 0
1560// %3 = icmp eq i1 %2, true
1561// br i1 %3, label %cond.load, label %else
1562//
1563//cond.load: ; preds = %0
1564// %4 = getelementptr i32* %1, i32 0
1565// %5 = load i32* %4
1566// %6 = insertelement <16 x i32> undef, i32 %5, i32 0
1567// br label %else
1568//
1569//else: ; preds = %0, %cond.load
1570// %res.phi.else = phi <16 x i32> [ %6, %cond.load ], [ undef, %0 ]
1571// %7 = extractelement <16 x i1> %mask, i32 1
1572// %8 = icmp eq i1 %7, true
1573// br i1 %8, label %cond.load1, label %else2
1574//
1575//cond.load1: ; preds = %else
1576// %9 = getelementptr i32* %1, i32 1
1577// %10 = load i32* %9
1578// %11 = insertelement <16 x i32> %res.phi.else, i32 %10, i32 1
1579// br label %else2
1580//
1581//else2: ; preds = %else, %cond.load1
1582// %res.phi.else3 = phi <16 x i32> [ %11, %cond.load1 ], [ %res.phi.else, %else ]
1583// %12 = extractelement <16 x i1> %mask, i32 2
1584// %13 = icmp eq i1 %12, true
1585// br i1 %13, label %cond.load4, label %else5
1586//
1587static void scalarizeMaskedLoad(CallInst *CI) {
1588 Value *Ptr = CI->getArgOperand(0);
1589 Value *Alignment = CI->getArgOperand(1);
1590 Value *Mask = CI->getArgOperand(2);
1591 Value *Src0 = CI->getArgOperand(3);
1592
1593 unsigned AlignVal = cast<ConstantInt>(Alignment)->getZExtValue();
1594 VectorType *VecType = dyn_cast<VectorType>(CI->getType());
1595 assert(VecType && "Unexpected return type of masked load intrinsic")((VecType && "Unexpected return type of masked load intrinsic"
) ? static_cast<void> (0) : __assert_fail ("VecType && \"Unexpected return type of masked load intrinsic\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 1595, __PRETTY_FUNCTION__))
;
1596
1597 Type *EltTy = CI->getType()->getVectorElementType();
1598
1599 IRBuilder<> Builder(CI->getContext());
1600 Instruction *InsertPt = CI;
1601 BasicBlock *IfBlock = CI->getParent();
1602 BasicBlock *CondBlock = nullptr;
1603 BasicBlock *PrevIfBlock = CI->getParent();
1604
1605 Builder.SetInsertPoint(InsertPt);
1606 Builder.SetCurrentDebugLocation(CI->getDebugLoc());
1607
1608 // Short-cut if the mask is all-true.
1609 bool IsAllOnesMask = isa<Constant>(Mask) &&
1610 cast<Constant>(Mask)->isAllOnesValue();
1611
1612 if (IsAllOnesMask) {
1613 Value *NewI = Builder.CreateAlignedLoad(Ptr, AlignVal);
1614 CI->replaceAllUsesWith(NewI);
1615 CI->eraseFromParent();
1616 return;
1617 }
1618
1619 // Adjust alignment for the scalar instruction.
1620 AlignVal = std::min(AlignVal, VecType->getScalarSizeInBits()/8);
1621 // Bitcast %addr fron i8* to EltTy*
1622 Type *NewPtrType =
1623 EltTy->getPointerTo(cast<PointerType>(Ptr->getType())->getAddressSpace());
1624 Value *FirstEltPtr = Builder.CreateBitCast(Ptr, NewPtrType);
1625 unsigned VectorWidth = VecType->getNumElements();
1626
1627 Value *UndefVal = UndefValue::get(VecType);
1628
1629 // The result vector
1630 Value *VResult = UndefVal;
1631
1632 if (isa<ConstantVector>(Mask)) {
1633 for (unsigned Idx = 0; Idx < VectorWidth; ++Idx) {
1634 if (cast<ConstantVector>(Mask)->getOperand(Idx)->isNullValue())
1635 continue;
1636 Value *Gep =
1637 Builder.CreateInBoundsGEP(EltTy, FirstEltPtr, Builder.getInt32(Idx));
1638 LoadInst* Load = Builder.CreateAlignedLoad(Gep, AlignVal);
1639 VResult = Builder.CreateInsertElement(VResult, Load,
1640 Builder.getInt32(Idx));
1641 }
1642 Value *NewI = Builder.CreateSelect(Mask, VResult, Src0);
1643 CI->replaceAllUsesWith(NewI);
1644 CI->eraseFromParent();
1645 return;
1646 }
1647
1648 PHINode *Phi = nullptr;
1649 Value *PrevPhi = UndefVal;
1650
1651 for (unsigned Idx = 0; Idx < VectorWidth; ++Idx) {
1652
1653 // Fill the "else" block, created in the previous iteration
1654 //
1655 // %res.phi.else3 = phi <16 x i32> [ %11, %cond.load1 ], [ %res.phi.else, %else ]
1656 // %mask_1 = extractelement <16 x i1> %mask, i32 Idx
1657 // %to_load = icmp eq i1 %mask_1, true
1658 // br i1 %to_load, label %cond.load, label %else
1659 //
1660 if (Idx > 0) {
1661 Phi = Builder.CreatePHI(VecType, 2, "res.phi.else");
1662 Phi->addIncoming(VResult, CondBlock);
1663 Phi->addIncoming(PrevPhi, PrevIfBlock);
1664 PrevPhi = Phi;
1665 VResult = Phi;
1666 }
1667
1668 Value *Predicate = Builder.CreateExtractElement(Mask, Builder.getInt32(Idx));
1669 Value *Cmp = Builder.CreateICmp(ICmpInst::ICMP_EQ, Predicate,
1670 ConstantInt::get(Predicate->getType(), 1));
1671
1672 // Create "cond" block
1673 //
1674 // %EltAddr = getelementptr i32* %1, i32 0
1675 // %Elt = load i32* %EltAddr
1676 // VResult = insertelement <16 x i32> VResult, i32 %Elt, i32 Idx
1677 //
1678 CondBlock = IfBlock->splitBasicBlock(InsertPt->getIterator(), "cond.load");
1679 Builder.SetInsertPoint(InsertPt);
1680
1681 Value *Gep =
1682 Builder.CreateInBoundsGEP(EltTy, FirstEltPtr, Builder.getInt32(Idx));
1683 LoadInst *Load = Builder.CreateAlignedLoad(Gep, AlignVal);
1684 VResult = Builder.CreateInsertElement(VResult, Load, Builder.getInt32(Idx));
1685
1686 // Create "else" block, fill it in the next iteration
1687 BasicBlock *NewIfBlock =
1688 CondBlock->splitBasicBlock(InsertPt->getIterator(), "else");
1689 Builder.SetInsertPoint(InsertPt);
1690 Instruction *OldBr = IfBlock->getTerminator();
1691 BranchInst::Create(CondBlock, NewIfBlock, Cmp, OldBr);
1692 OldBr->eraseFromParent();
1693 PrevIfBlock = IfBlock;
1694 IfBlock = NewIfBlock;
1695 }
1696
1697 Phi = Builder.CreatePHI(VecType, 2, "res.phi.select");
1698 Phi->addIncoming(VResult, CondBlock);
1699 Phi->addIncoming(PrevPhi, PrevIfBlock);
1700 Value *NewI = Builder.CreateSelect(Mask, Phi, Src0);
1701 CI->replaceAllUsesWith(NewI);
1702 CI->eraseFromParent();
1703}
1704
1705// Translate a masked store intrinsic, like
1706// void @llvm.masked.store(<16 x i32> %src, <16 x i32>* %addr, i32 align,
1707// <16 x i1> %mask)
1708// to a chain of basic blocks, that stores element one-by-one if
1709// the appropriate mask bit is set
1710//
1711// %1 = bitcast i8* %addr to i32*
1712// %2 = extractelement <16 x i1> %mask, i32 0
1713// %3 = icmp eq i1 %2, true
1714// br i1 %3, label %cond.store, label %else
1715//
1716// cond.store: ; preds = %0
1717// %4 = extractelement <16 x i32> %val, i32 0
1718// %5 = getelementptr i32* %1, i32 0
1719// store i32 %4, i32* %5
1720// br label %else
1721//
1722// else: ; preds = %0, %cond.store
1723// %6 = extractelement <16 x i1> %mask, i32 1
1724// %7 = icmp eq i1 %6, true
1725// br i1 %7, label %cond.store1, label %else2
1726//
1727// cond.store1: ; preds = %else
1728// %8 = extractelement <16 x i32> %val, i32 1
1729// %9 = getelementptr i32* %1, i32 1
1730// store i32 %8, i32* %9
1731// br label %else2
1732// . . .
1733static void scalarizeMaskedStore(CallInst *CI) {
1734 Value *Src = CI->getArgOperand(0);
1735 Value *Ptr = CI->getArgOperand(1);
1736 Value *Alignment = CI->getArgOperand(2);
1737 Value *Mask = CI->getArgOperand(3);
1738
1739 unsigned AlignVal = cast<ConstantInt>(Alignment)->getZExtValue();
1740 VectorType *VecType = dyn_cast<VectorType>(Src->getType());
1741 assert(VecType && "Unexpected data type in masked store intrinsic")((VecType && "Unexpected data type in masked store intrinsic"
) ? static_cast<void> (0) : __assert_fail ("VecType && \"Unexpected data type in masked store intrinsic\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 1741, __PRETTY_FUNCTION__))
;
1742
1743 Type *EltTy = VecType->getElementType();
1744
1745 IRBuilder<> Builder(CI->getContext());
1746 Instruction *InsertPt = CI;
1747 BasicBlock *IfBlock = CI->getParent();
1748 Builder.SetInsertPoint(InsertPt);
1749 Builder.SetCurrentDebugLocation(CI->getDebugLoc());
1750
1751 // Short-cut if the mask is all-true.
1752 bool IsAllOnesMask = isa<Constant>(Mask) &&
1753 cast<Constant>(Mask)->isAllOnesValue();
1754
1755 if (IsAllOnesMask) {
1756 Builder.CreateAlignedStore(Src, Ptr, AlignVal);
1757 CI->eraseFromParent();
1758 return;
1759 }
1760
1761 // Adjust alignment for the scalar instruction.
1762 AlignVal = std::max(AlignVal, VecType->getScalarSizeInBits()/8);
1763 // Bitcast %addr fron i8* to EltTy*
1764 Type *NewPtrType =
1765 EltTy->getPointerTo(cast<PointerType>(Ptr->getType())->getAddressSpace());
1766 Value *FirstEltPtr = Builder.CreateBitCast(Ptr, NewPtrType);
1767 unsigned VectorWidth = VecType->getNumElements();
1768
1769 if (isa<ConstantVector>(Mask)) {
1770 for (unsigned Idx = 0; Idx < VectorWidth; ++Idx) {
1771 if (cast<ConstantVector>(Mask)->getOperand(Idx)->isNullValue())
1772 continue;
1773 Value *OneElt = Builder.CreateExtractElement(Src, Builder.getInt32(Idx));
1774 Value *Gep =
1775 Builder.CreateInBoundsGEP(EltTy, FirstEltPtr, Builder.getInt32(Idx));
1776 Builder.CreateAlignedStore(OneElt, Gep, AlignVal);
1777 }
1778 CI->eraseFromParent();
1779 return;
1780 }
1781
1782 for (unsigned Idx = 0; Idx < VectorWidth; ++Idx) {
1783
1784 // Fill the "else" block, created in the previous iteration
1785 //
1786 // %mask_1 = extractelement <16 x i1> %mask, i32 Idx
1787 // %to_store = icmp eq i1 %mask_1, true
1788 // br i1 %to_store, label %cond.store, label %else
1789 //
1790 Value *Predicate = Builder.CreateExtractElement(Mask, Builder.getInt32(Idx));
1791 Value *Cmp = Builder.CreateICmp(ICmpInst::ICMP_EQ, Predicate,
1792 ConstantInt::get(Predicate->getType(), 1));
1793
1794 // Create "cond" block
1795 //
1796 // %OneElt = extractelement <16 x i32> %Src, i32 Idx
1797 // %EltAddr = getelementptr i32* %1, i32 0
1798 // %store i32 %OneElt, i32* %EltAddr
1799 //
1800 BasicBlock *CondBlock =
1801 IfBlock->splitBasicBlock(InsertPt->getIterator(), "cond.store");
1802 Builder.SetInsertPoint(InsertPt);
1803
1804 Value *OneElt = Builder.CreateExtractElement(Src, Builder.getInt32(Idx));
1805 Value *Gep =
1806 Builder.CreateInBoundsGEP(EltTy, FirstEltPtr, Builder.getInt32(Idx));
1807 Builder.CreateAlignedStore(OneElt, Gep, AlignVal);
1808
1809 // Create "else" block, fill it in the next iteration
1810 BasicBlock *NewIfBlock =
1811 CondBlock->splitBasicBlock(InsertPt->getIterator(), "else");
1812 Builder.SetInsertPoint(InsertPt);
1813 Instruction *OldBr = IfBlock->getTerminator();
1814 BranchInst::Create(CondBlock, NewIfBlock, Cmp, OldBr);
1815 OldBr->eraseFromParent();
1816 IfBlock = NewIfBlock;
1817 }
1818 CI->eraseFromParent();
1819}
1820
1821// Translate a masked gather intrinsic like
1822// <16 x i32 > @llvm.masked.gather.v16i32( <16 x i32*> %Ptrs, i32 4,
1823// <16 x i1> %Mask, <16 x i32> %Src)
1824// to a chain of basic blocks, with loading element one-by-one if
1825// the appropriate mask bit is set
1826//
1827// % Ptrs = getelementptr i32, i32* %base, <16 x i64> %ind
1828// % Mask0 = extractelement <16 x i1> %Mask, i32 0
1829// % ToLoad0 = icmp eq i1 % Mask0, true
1830// br i1 % ToLoad0, label %cond.load, label %else
1831//
1832// cond.load:
1833// % Ptr0 = extractelement <16 x i32*> %Ptrs, i32 0
1834// % Load0 = load i32, i32* % Ptr0, align 4
1835// % Res0 = insertelement <16 x i32> undef, i32 % Load0, i32 0
1836// br label %else
1837//
1838// else:
1839// %res.phi.else = phi <16 x i32>[% Res0, %cond.load], [undef, % 0]
1840// % Mask1 = extractelement <16 x i1> %Mask, i32 1
1841// % ToLoad1 = icmp eq i1 % Mask1, true
1842// br i1 % ToLoad1, label %cond.load1, label %else2
1843//
1844// cond.load1:
1845// % Ptr1 = extractelement <16 x i32*> %Ptrs, i32 1
1846// % Load1 = load i32, i32* % Ptr1, align 4
1847// % Res1 = insertelement <16 x i32> %res.phi.else, i32 % Load1, i32 1
1848// br label %else2
1849// . . .
1850// % Result = select <16 x i1> %Mask, <16 x i32> %res.phi.select, <16 x i32> %Src
1851// ret <16 x i32> %Result
1852static void scalarizeMaskedGather(CallInst *CI) {
1853 Value *Ptrs = CI->getArgOperand(0);
1854 Value *Alignment = CI->getArgOperand(1);
1855 Value *Mask = CI->getArgOperand(2);
1856 Value *Src0 = CI->getArgOperand(3);
1857
1858 VectorType *VecType = dyn_cast<VectorType>(CI->getType());
1859
1860 assert(VecType && "Unexpected return type of masked load intrinsic")((VecType && "Unexpected return type of masked load intrinsic"
) ? static_cast<void> (0) : __assert_fail ("VecType && \"Unexpected return type of masked load intrinsic\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 1860, __PRETTY_FUNCTION__))
;
1861
1862 IRBuilder<> Builder(CI->getContext());
1863 Instruction *InsertPt = CI;
1864 BasicBlock *IfBlock = CI->getParent();
1865 BasicBlock *CondBlock = nullptr;
1866 BasicBlock *PrevIfBlock = CI->getParent();
1867 Builder.SetInsertPoint(InsertPt);
1868 unsigned AlignVal = cast<ConstantInt>(Alignment)->getZExtValue();
1869
1870 Builder.SetCurrentDebugLocation(CI->getDebugLoc());
1871
1872 Value *UndefVal = UndefValue::get(VecType);
1873
1874 // The result vector
1875 Value *VResult = UndefVal;
1876 unsigned VectorWidth = VecType->getNumElements();
1877
1878 // Shorten the way if the mask is a vector of constants.
1879 bool IsConstMask = isa<ConstantVector>(Mask);
1880
1881 if (IsConstMask) {
1882 for (unsigned Idx = 0; Idx < VectorWidth; ++Idx) {
1883 if (cast<ConstantVector>(Mask)->getOperand(Idx)->isNullValue())
1884 continue;
1885 Value *Ptr = Builder.CreateExtractElement(Ptrs, Builder.getInt32(Idx),
1886 "Ptr" + Twine(Idx));
1887 LoadInst *Load = Builder.CreateAlignedLoad(Ptr, AlignVal,
1888 "Load" + Twine(Idx));
1889 VResult = Builder.CreateInsertElement(VResult, Load,
1890 Builder.getInt32(Idx),
1891 "Res" + Twine(Idx));
1892 }
1893 Value *NewI = Builder.CreateSelect(Mask, VResult, Src0);
1894 CI->replaceAllUsesWith(NewI);
1895 CI->eraseFromParent();
1896 return;
1897 }
1898
1899 PHINode *Phi = nullptr;
1900 Value *PrevPhi = UndefVal;
1901
1902 for (unsigned Idx = 0; Idx < VectorWidth; ++Idx) {
1903
1904 // Fill the "else" block, created in the previous iteration
1905 //
1906 // %Mask1 = extractelement <16 x i1> %Mask, i32 1
1907 // %ToLoad1 = icmp eq i1 %Mask1, true
1908 // br i1 %ToLoad1, label %cond.load, label %else
1909 //
1910 if (Idx > 0) {
1911 Phi = Builder.CreatePHI(VecType, 2, "res.phi.else");
1912 Phi->addIncoming(VResult, CondBlock);
1913 Phi->addIncoming(PrevPhi, PrevIfBlock);
1914 PrevPhi = Phi;
1915 VResult = Phi;
1916 }
1917
1918 Value *Predicate = Builder.CreateExtractElement(Mask,
1919 Builder.getInt32(Idx),
1920 "Mask" + Twine(Idx));
1921 Value *Cmp = Builder.CreateICmp(ICmpInst::ICMP_EQ, Predicate,
1922 ConstantInt::get(Predicate->getType(), 1),
1923 "ToLoad" + Twine(Idx));
1924
1925 // Create "cond" block
1926 //
1927 // %EltAddr = getelementptr i32* %1, i32 0
1928 // %Elt = load i32* %EltAddr
1929 // VResult = insertelement <16 x i32> VResult, i32 %Elt, i32 Idx
1930 //
1931 CondBlock = IfBlock->splitBasicBlock(InsertPt, "cond.load");
1932 Builder.SetInsertPoint(InsertPt);
1933
1934 Value *Ptr = Builder.CreateExtractElement(Ptrs, Builder.getInt32(Idx),
1935 "Ptr" + Twine(Idx));
1936 LoadInst *Load = Builder.CreateAlignedLoad(Ptr, AlignVal,
1937 "Load" + Twine(Idx));
1938 VResult = Builder.CreateInsertElement(VResult, Load, Builder.getInt32(Idx),
1939 "Res" + Twine(Idx));
1940
1941 // Create "else" block, fill it in the next iteration
1942 BasicBlock *NewIfBlock = CondBlock->splitBasicBlock(InsertPt, "else");
1943 Builder.SetInsertPoint(InsertPt);
1944 Instruction *OldBr = IfBlock->getTerminator();
1945 BranchInst::Create(CondBlock, NewIfBlock, Cmp, OldBr);
1946 OldBr->eraseFromParent();
1947 PrevIfBlock = IfBlock;
1948 IfBlock = NewIfBlock;
1949 }
1950
1951 Phi = Builder.CreatePHI(VecType, 2, "res.phi.select");
1952 Phi->addIncoming(VResult, CondBlock);
1953 Phi->addIncoming(PrevPhi, PrevIfBlock);
1954 Value *NewI = Builder.CreateSelect(Mask, Phi, Src0);
1955 CI->replaceAllUsesWith(NewI);
1956 CI->eraseFromParent();
1957}
1958
1959// Translate a masked scatter intrinsic, like
1960// void @llvm.masked.scatter.v16i32(<16 x i32> %Src, <16 x i32*>* %Ptrs, i32 4,
1961// <16 x i1> %Mask)
1962// to a chain of basic blocks, that stores element one-by-one if
1963// the appropriate mask bit is set.
1964//
1965// % Ptrs = getelementptr i32, i32* %ptr, <16 x i64> %ind
1966// % Mask0 = extractelement <16 x i1> % Mask, i32 0
1967// % ToStore0 = icmp eq i1 % Mask0, true
1968// br i1 %ToStore0, label %cond.store, label %else
1969//
1970// cond.store:
1971// % Elt0 = extractelement <16 x i32> %Src, i32 0
1972// % Ptr0 = extractelement <16 x i32*> %Ptrs, i32 0
1973// store i32 %Elt0, i32* % Ptr0, align 4
1974// br label %else
1975//
1976// else:
1977// % Mask1 = extractelement <16 x i1> % Mask, i32 1
1978// % ToStore1 = icmp eq i1 % Mask1, true
1979// br i1 % ToStore1, label %cond.store1, label %else2
1980//
1981// cond.store1:
1982// % Elt1 = extractelement <16 x i32> %Src, i32 1
1983// % Ptr1 = extractelement <16 x i32*> %Ptrs, i32 1
1984// store i32 % Elt1, i32* % Ptr1, align 4
1985// br label %else2
1986// . . .
1987static void scalarizeMaskedScatter(CallInst *CI) {
1988 Value *Src = CI->getArgOperand(0);
1989 Value *Ptrs = CI->getArgOperand(1);
1990 Value *Alignment = CI->getArgOperand(2);
1991 Value *Mask = CI->getArgOperand(3);
1992
1993 assert(isa<VectorType>(Src->getType()) &&((isa<VectorType>(Src->getType()) && "Unexpected data type in masked scatter intrinsic"
) ? static_cast<void> (0) : __assert_fail ("isa<VectorType>(Src->getType()) && \"Unexpected data type in masked scatter intrinsic\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 1994, __PRETTY_FUNCTION__))
1994 "Unexpected data type in masked scatter intrinsic")((isa<VectorType>(Src->getType()) && "Unexpected data type in masked scatter intrinsic"
) ? static_cast<void> (0) : __assert_fail ("isa<VectorType>(Src->getType()) && \"Unexpected data type in masked scatter intrinsic\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 1994, __PRETTY_FUNCTION__))
;
1995 assert(isa<VectorType>(Ptrs->getType()) &&((isa<VectorType>(Ptrs->getType()) && isa<
PointerType>(Ptrs->getType()->getVectorElementType()
) && "Vector of pointers is expected in masked scatter intrinsic"
) ? static_cast<void> (0) : __assert_fail ("isa<VectorType>(Ptrs->getType()) && isa<PointerType>(Ptrs->getType()->getVectorElementType()) && \"Vector of pointers is expected in masked scatter intrinsic\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 1997, __PRETTY_FUNCTION__))
1996 isa<PointerType>(Ptrs->getType()->getVectorElementType()) &&((isa<VectorType>(Ptrs->getType()) && isa<
PointerType>(Ptrs->getType()->getVectorElementType()
) && "Vector of pointers is expected in masked scatter intrinsic"
) ? static_cast<void> (0) : __assert_fail ("isa<VectorType>(Ptrs->getType()) && isa<PointerType>(Ptrs->getType()->getVectorElementType()) && \"Vector of pointers is expected in masked scatter intrinsic\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 1997, __PRETTY_FUNCTION__))
1997 "Vector of pointers is expected in masked scatter intrinsic")((isa<VectorType>(Ptrs->getType()) && isa<
PointerType>(Ptrs->getType()->getVectorElementType()
) && "Vector of pointers is expected in masked scatter intrinsic"
) ? static_cast<void> (0) : __assert_fail ("isa<VectorType>(Ptrs->getType()) && isa<PointerType>(Ptrs->getType()->getVectorElementType()) && \"Vector of pointers is expected in masked scatter intrinsic\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 1997, __PRETTY_FUNCTION__))
;
1998
1999 IRBuilder<> Builder(CI->getContext());
2000 Instruction *InsertPt = CI;
2001 BasicBlock *IfBlock = CI->getParent();
2002 Builder.SetInsertPoint(InsertPt);
2003 Builder.SetCurrentDebugLocation(CI->getDebugLoc());
2004
2005 unsigned AlignVal = cast<ConstantInt>(Alignment)->getZExtValue();
2006 unsigned VectorWidth = Src->getType()->getVectorNumElements();
2007
2008 // Shorten the way if the mask is a vector of constants.
2009 bool IsConstMask = isa<ConstantVector>(Mask);
2010
2011 if (IsConstMask) {
2012 for (unsigned Idx = 0; Idx < VectorWidth; ++Idx) {
2013 if (cast<ConstantVector>(Mask)->getOperand(Idx)->isNullValue())
2014 continue;
2015 Value *OneElt = Builder.CreateExtractElement(Src, Builder.getInt32(Idx),
2016 "Elt" + Twine(Idx));
2017 Value *Ptr = Builder.CreateExtractElement(Ptrs, Builder.getInt32(Idx),
2018 "Ptr" + Twine(Idx));
2019 Builder.CreateAlignedStore(OneElt, Ptr, AlignVal);
2020 }
2021 CI->eraseFromParent();
2022 return;
2023 }
2024 for (unsigned Idx = 0; Idx < VectorWidth; ++Idx) {
2025 // Fill the "else" block, created in the previous iteration
2026 //
2027 // % Mask1 = extractelement <16 x i1> % Mask, i32 Idx
2028 // % ToStore = icmp eq i1 % Mask1, true
2029 // br i1 % ToStore, label %cond.store, label %else
2030 //
2031 Value *Predicate = Builder.CreateExtractElement(Mask,
2032 Builder.getInt32(Idx),
2033 "Mask" + Twine(Idx));
2034 Value *Cmp =
2035 Builder.CreateICmp(ICmpInst::ICMP_EQ, Predicate,
2036 ConstantInt::get(Predicate->getType(), 1),
2037 "ToStore" + Twine(Idx));
2038
2039 // Create "cond" block
2040 //
2041 // % Elt1 = extractelement <16 x i32> %Src, i32 1
2042 // % Ptr1 = extractelement <16 x i32*> %Ptrs, i32 1
2043 // %store i32 % Elt1, i32* % Ptr1
2044 //
2045 BasicBlock *CondBlock = IfBlock->splitBasicBlock(InsertPt, "cond.store");
2046 Builder.SetInsertPoint(InsertPt);
2047
2048 Value *OneElt = Builder.CreateExtractElement(Src, Builder.getInt32(Idx),
2049 "Elt" + Twine(Idx));
2050 Value *Ptr = Builder.CreateExtractElement(Ptrs, Builder.getInt32(Idx),
2051 "Ptr" + Twine(Idx));
2052 Builder.CreateAlignedStore(OneElt, Ptr, AlignVal);
2053
2054 // Create "else" block, fill it in the next iteration
2055 BasicBlock *NewIfBlock = CondBlock->splitBasicBlock(InsertPt, "else");
2056 Builder.SetInsertPoint(InsertPt);
2057 Instruction *OldBr = IfBlock->getTerminator();
2058 BranchInst::Create(CondBlock, NewIfBlock, Cmp, OldBr);
2059 OldBr->eraseFromParent();
2060 IfBlock = NewIfBlock;
2061 }
2062 CI->eraseFromParent();
2063}
2064
2065/// If counting leading or trailing zeros is an expensive operation and a zero
2066/// input is defined, add a check for zero to avoid calling the intrinsic.
2067///
2068/// We want to transform:
2069/// %z = call i64 @llvm.cttz.i64(i64 %A, i1 false)
2070///
2071/// into:
2072/// entry:
2073/// %cmpz = icmp eq i64 %A, 0
2074/// br i1 %cmpz, label %cond.end, label %cond.false
2075/// cond.false:
2076/// %z = call i64 @llvm.cttz.i64(i64 %A, i1 true)
2077/// br label %cond.end
2078/// cond.end:
2079/// %ctz = phi i64 [ 64, %entry ], [ %z, %cond.false ]
2080///
2081/// If the transform is performed, return true and set ModifiedDT to true.
2082static bool despeculateCountZeros(IntrinsicInst *CountZeros,
2083 const TargetLowering *TLI,
2084 const DataLayout *DL,
2085 bool &ModifiedDT) {
2086 if (!TLI || !DL)
2087 return false;
2088
2089 // If a zero input is undefined, it doesn't make sense to despeculate that.
2090 if (match(CountZeros->getOperand(1), m_One()))
2091 return false;
2092
2093 // If it's cheap to speculate, there's nothing to do.
2094 auto IntrinsicID = CountZeros->getIntrinsicID();
2095 if ((IntrinsicID == Intrinsic::cttz && TLI->isCheapToSpeculateCttz()) ||
2096 (IntrinsicID == Intrinsic::ctlz && TLI->isCheapToSpeculateCtlz()))
2097 return false;
2098
2099 // Only handle legal scalar cases. Anything else requires too much work.
2100 Type *Ty = CountZeros->getType();
2101 unsigned SizeInBits = Ty->getPrimitiveSizeInBits();
2102 if (Ty->isVectorTy() || SizeInBits > DL->getLargestLegalIntTypeSizeInBits())
2103 return false;
2104
2105 // The intrinsic will be sunk behind a compare against zero and branch.
2106 BasicBlock *StartBlock = CountZeros->getParent();
2107 BasicBlock *CallBlock = StartBlock->splitBasicBlock(CountZeros, "cond.false");
2108
2109 // Create another block after the count zero intrinsic. A PHI will be added
2110 // in this block to select the result of the intrinsic or the bit-width
2111 // constant if the input to the intrinsic is zero.
2112 BasicBlock::iterator SplitPt = ++(BasicBlock::iterator(CountZeros));
2113 BasicBlock *EndBlock = CallBlock->splitBasicBlock(SplitPt, "cond.end");
2114
2115 // Set up a builder to create a compare, conditional branch, and PHI.
2116 IRBuilder<> Builder(CountZeros->getContext());
2117 Builder.SetInsertPoint(StartBlock->getTerminator());
2118 Builder.SetCurrentDebugLocation(CountZeros->getDebugLoc());
2119
2120 // Replace the unconditional branch that was created by the first split with
2121 // a compare against zero and a conditional branch.
2122 Value *Zero = Constant::getNullValue(Ty);
2123 Value *Cmp = Builder.CreateICmpEQ(CountZeros->getOperand(0), Zero, "cmpz");
2124 Builder.CreateCondBr(Cmp, EndBlock, CallBlock);
2125 StartBlock->getTerminator()->eraseFromParent();
2126
2127 // Create a PHI in the end block to select either the output of the intrinsic
2128 // or the bit width of the operand.
2129 Builder.SetInsertPoint(&EndBlock->front());
2130 PHINode *PN = Builder.CreatePHI(Ty, 2, "ctz");
2131 CountZeros->replaceAllUsesWith(PN);
2132 Value *BitWidth = Builder.getInt(APInt(SizeInBits, SizeInBits));
2133 PN->addIncoming(BitWidth, StartBlock);
2134 PN->addIncoming(CountZeros, CallBlock);
2135
2136 // We are explicitly handling the zero case, so we can set the intrinsic's
2137 // undefined zero argument to 'true'. This will also prevent reprocessing the
2138 // intrinsic; we only despeculate when a zero input is defined.
2139 CountZeros->setArgOperand(1, Builder.getTrue());
2140 ModifiedDT = true;
2141 return true;
2142}
2143
2144bool CodeGenPrepare::optimizeCallInst(CallInst *CI, bool& ModifiedDT) {
2145 BasicBlock *BB = CI->getParent();
2146
2147 // Lower inline assembly if we can.
2148 // If we found an inline asm expession, and if the target knows how to
2149 // lower it to normal LLVM code, do so now.
2150 if (TLI && isa<InlineAsm>(CI->getCalledValue())) {
2151 if (TLI->ExpandInlineAsm(CI)) {
2152 // Avoid invalidating the iterator.
2153 CurInstIterator = BB->begin();
2154 // Avoid processing instructions out of order, which could cause
2155 // reuse before a value is defined.
2156 SunkAddrs.clear();
2157 return true;
2158 }
2159 // Sink address computing for memory operands into the block.
2160 if (optimizeInlineAsmInst(CI))
2161 return true;
2162 }
2163
2164 // Align the pointer arguments to this call if the target thinks it's a good
2165 // idea
2166 unsigned MinSize, PrefAlign;
2167 if (TLI && TLI->shouldAlignPointerArgs(CI, MinSize, PrefAlign)) {
2168 for (auto &Arg : CI->arg_operands()) {
2169 // We want to align both objects whose address is used directly and
2170 // objects whose address is used in casts and GEPs, though it only makes
2171 // sense for GEPs if the offset is a multiple of the desired alignment and
2172 // if size - offset meets the size threshold.
2173 if (!Arg->getType()->isPointerTy())
2174 continue;
2175 APInt Offset(DL->getPointerSizeInBits(
2176 cast<PointerType>(Arg->getType())->getAddressSpace()),
2177 0);
2178 Value *Val = Arg->stripAndAccumulateInBoundsConstantOffsets(*DL, Offset);
2179 uint64_t Offset2 = Offset.getLimitedValue();
2180 if ((Offset2 & (PrefAlign-1)) != 0)
2181 continue;
2182 AllocaInst *AI;
2183 if ((AI = dyn_cast<AllocaInst>(Val)) && AI->getAlignment() < PrefAlign &&
2184 DL->getTypeAllocSize(AI->getAllocatedType()) >= MinSize + Offset2)
2185 AI->setAlignment(PrefAlign);
2186 // Global variables can only be aligned if they are defined in this
2187 // object (i.e. they are uniquely initialized in this object), and
2188 // over-aligning global variables that have an explicit section is
2189 // forbidden.
2190 GlobalVariable *GV;
2191 if ((GV = dyn_cast<GlobalVariable>(Val)) && GV->canIncreaseAlignment() &&
2192 GV->getPointerAlignment(*DL) < PrefAlign &&
2193 DL->getTypeAllocSize(GV->getValueType()) >=
2194 MinSize + Offset2)
2195 GV->setAlignment(PrefAlign);
2196 }
2197 // If this is a memcpy (or similar) then we may be able to improve the
2198 // alignment
2199 if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(CI)) {
2200 unsigned Align = getKnownAlignment(MI->getDest(), *DL);
2201 if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(MI))
2202 Align = std::min(Align, getKnownAlignment(MTI->getSource(), *DL));
2203 if (Align > MI->getAlignment())
2204 MI->setAlignment(ConstantInt::get(MI->getAlignmentType(), Align));
2205 }
2206 }
2207
2208 // If we have a cold call site, try to sink addressing computation into the
2209 // cold block. This interacts with our handling for loads and stores to
2210 // ensure that we can fold all uses of a potential addressing computation
2211 // into their uses. TODO: generalize this to work over profiling data
2212 if (!OptSize && CI->hasFnAttr(Attribute::Cold))
2213 for (auto &Arg : CI->arg_operands()) {
2214 if (!Arg->getType()->isPointerTy())
2215 continue;
2216 unsigned AS = Arg->getType()->getPointerAddressSpace();
2217 return optimizeMemoryInst(CI, Arg, Arg->getType(), AS);
2218 }
2219
2220 IntrinsicInst *II = dyn_cast<IntrinsicInst>(CI);
2221 if (II) {
2222 switch (II->getIntrinsicID()) {
2223 default: break;
2224 case Intrinsic::objectsize: {
2225 // Lower all uses of llvm.objectsize.*
2226 ConstantInt *RetVal =
2227 lowerObjectSizeCall(II, *DL, TLInfo, /*MustSucceed=*/true);
2228 // Substituting this can cause recursive simplifications, which can
2229 // invalidate our iterator. Use a WeakVH to hold onto it in case this
2230 // happens.
2231 Value *CurValue = &*CurInstIterator;
2232 WeakVH IterHandle(CurValue);
2233
2234 replaceAndRecursivelySimplify(CI, RetVal, TLInfo, nullptr);
2235
2236 // If the iterator instruction was recursively deleted, start over at the
2237 // start of the block.
2238 if (IterHandle != CurValue) {
2239 CurInstIterator = BB->begin();
2240 SunkAddrs.clear();
2241 }
2242 return true;
2243 }
2244 case Intrinsic::masked_load: {
2245 // Scalarize unsupported vector masked load
2246 if (!TTI->isLegalMaskedLoad(CI->getType())) {
2247 scalarizeMaskedLoad(CI);
2248 ModifiedDT = true;
2249 return true;
2250 }
2251 return false;
2252 }
2253 case Intrinsic::masked_store: {
2254 if (!TTI->isLegalMaskedStore(CI->getArgOperand(0)->getType())) {
2255 scalarizeMaskedStore(CI);
2256 ModifiedDT = true;
2257 return true;
2258 }
2259 return false;
2260 }
2261 case Intrinsic::masked_gather: {
2262 if (!TTI->isLegalMaskedGather(CI->getType())) {
2263 scalarizeMaskedGather(CI);
2264 ModifiedDT = true;
2265 return true;
2266 }
2267 return false;
2268 }
2269 case Intrinsic::masked_scatter: {
2270 if (!TTI->isLegalMaskedScatter(CI->getArgOperand(0)->getType())) {
2271 scalarizeMaskedScatter(CI);
2272 ModifiedDT = true;
2273 return true;
2274 }
2275 return false;
2276 }
2277 case Intrinsic::aarch64_stlxr:
2278 case Intrinsic::aarch64_stxr: {
2279 ZExtInst *ExtVal = dyn_cast<ZExtInst>(CI->getArgOperand(0));
2280 if (!ExtVal || !ExtVal->hasOneUse() ||
2281 ExtVal->getParent() == CI->getParent())
2282 return false;
2283 // Sink a zext feeding stlxr/stxr before it, so it can be folded into it.
2284 ExtVal->moveBefore(CI);
2285 // Mark this instruction as "inserted by CGP", so that other
2286 // optimizations don't touch it.
2287 InsertedInsts.insert(ExtVal);
2288 return true;
2289 }
2290 case Intrinsic::invariant_group_barrier:
2291 II->replaceAllUsesWith(II->getArgOperand(0));
2292 II->eraseFromParent();
2293 return true;
2294
2295 case Intrinsic::cttz:
2296 case Intrinsic::ctlz:
2297 // If counting zeros is expensive, try to avoid it.
2298 return despeculateCountZeros(II, TLI, DL, ModifiedDT);
2299 }
2300
2301 if (TLI) {
2302 SmallVector<Value*, 2> PtrOps;
2303 Type *AccessTy;
2304 if (TLI->getAddrModeArguments(II, PtrOps, AccessTy))
2305 while (!PtrOps.empty()) {
2306 Value *PtrVal = PtrOps.pop_back_val();
2307 unsigned AS = PtrVal->getType()->getPointerAddressSpace();
2308 if (optimizeMemoryInst(II, PtrVal, AccessTy, AS))
2309 return true;
2310 }
2311 }
2312 }
2313
2314 // From here on out we're working with named functions.
2315 if (!CI->getCalledFunction()) return false;
2316
2317 // Lower all default uses of _chk calls. This is very similar
2318 // to what InstCombineCalls does, but here we are only lowering calls
2319 // to fortified library functions (e.g. __memcpy_chk) that have the default
2320 // "don't know" as the objectsize. Anything else should be left alone.
2321 FortifiedLibCallSimplifier Simplifier(TLInfo, true);
2322 if (Value *V = Simplifier.optimizeCall(CI)) {
2323 CI->replaceAllUsesWith(V);
2324 CI->eraseFromParent();
2325 return true;
2326 }
2327 return false;
2328}
2329
2330/// Look for opportunities to duplicate return instructions to the predecessor
2331/// to enable tail call optimizations. The case it is currently looking for is:
2332/// @code
2333/// bb0:
2334/// %tmp0 = tail call i32 @f0()
2335/// br label %return
2336/// bb1:
2337/// %tmp1 = tail call i32 @f1()
2338/// br label %return
2339/// bb2:
2340/// %tmp2 = tail call i32 @f2()
2341/// br label %return
2342/// return:
2343/// %retval = phi i32 [ %tmp0, %bb0 ], [ %tmp1, %bb1 ], [ %tmp2, %bb2 ]
2344/// ret i32 %retval
2345/// @endcode
2346///
2347/// =>
2348///
2349/// @code
2350/// bb0:
2351/// %tmp0 = tail call i32 @f0()
2352/// ret i32 %tmp0
2353/// bb1:
2354/// %tmp1 = tail call i32 @f1()
2355/// ret i32 %tmp1
2356/// bb2:
2357/// %tmp2 = tail call i32 @f2()
2358/// ret i32 %tmp2
2359/// @endcode
2360bool CodeGenPrepare::dupRetToEnableTailCallOpts(BasicBlock *BB) {
2361 if (!TLI)
2362 return false;
2363
2364 ReturnInst *RetI = dyn_cast<ReturnInst>(BB->getTerminator());
2365 if (!RetI)
2366 return false;
2367
2368 PHINode *PN = nullptr;
2369 BitCastInst *BCI = nullptr;
2370 Value *V = RetI->getReturnValue();
2371 if (V) {
2372 BCI = dyn_cast<BitCastInst>(V);
2373 if (BCI)
2374 V = BCI->getOperand(0);
2375
2376 PN = dyn_cast<PHINode>(V);
2377 if (!PN)
2378 return false;
2379 }
2380
2381 if (PN && PN->getParent() != BB)
2382 return false;
2383
2384 // Make sure there are no instructions between the PHI and return, or that the
2385 // return is the first instruction in the block.
2386 if (PN) {
2387 BasicBlock::iterator BI = BB->begin();
2388 do { ++BI; } while (isa<DbgInfoIntrinsic>(BI));
2389 if (&*BI == BCI)
2390 // Also skip over the bitcast.
2391 ++BI;
2392 if (&*BI != RetI)
2393 return false;
2394 } else {
2395 BasicBlock::iterator BI = BB->begin();
2396 while (isa<DbgInfoIntrinsic>(BI)) ++BI;
2397 if (&*BI != RetI)
2398 return false;
2399 }
2400
2401 /// Only dup the ReturnInst if the CallInst is likely to be emitted as a tail
2402 /// call.
2403 const Function *F = BB->getParent();
2404 SmallVector<CallInst*, 4> TailCalls;
2405 if (PN) {
2406 for (unsigned I = 0, E = PN->getNumIncomingValues(); I != E; ++I) {
2407 CallInst *CI = dyn_cast<CallInst>(PN->getIncomingValue(I));
2408 // Make sure the phi value is indeed produced by the tail call.
2409 if (CI && CI->hasOneUse() && CI->getParent() == PN->getIncomingBlock(I) &&
2410 TLI->mayBeEmittedAsTailCall(CI) &&
2411 attributesPermitTailCall(F, CI, RetI, *TLI))
2412 TailCalls.push_back(CI);
2413 }
2414 } else {
2415 SmallPtrSet<BasicBlock*, 4> VisitedBBs;
2416 for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB); PI != PE; ++PI) {
2417 if (!VisitedBBs.insert(*PI).second)
2418 continue;
2419
2420 BasicBlock::InstListType &InstList = (*PI)->getInstList();
2421 BasicBlock::InstListType::reverse_iterator RI = InstList.rbegin();
2422 BasicBlock::InstListType::reverse_iterator RE = InstList.rend();
2423 do { ++RI; } while (RI != RE && isa<DbgInfoIntrinsic>(&*RI));
2424 if (RI == RE)
2425 continue;
2426
2427 CallInst *CI = dyn_cast<CallInst>(&*RI);
2428 if (CI && CI->use_empty() && TLI->mayBeEmittedAsTailCall(CI) &&
2429 attributesPermitTailCall(F, CI, RetI, *TLI))
2430 TailCalls.push_back(CI);
2431 }
2432 }
2433
2434 bool Changed = false;
2435 for (unsigned i = 0, e = TailCalls.size(); i != e; ++i) {
2436 CallInst *CI = TailCalls[i];
2437 CallSite CS(CI);
2438
2439 // Conservatively require the attributes of the call to match those of the
2440 // return. Ignore noalias because it doesn't affect the call sequence.
2441 AttributeList CalleeAttrs = CS.getAttributes();
2442 if (AttrBuilder(CalleeAttrs, AttributeList::ReturnIndex)
2443 .removeAttribute(Attribute::NoAlias) !=
2444 AttrBuilder(CalleeAttrs, AttributeList::ReturnIndex)
2445 .removeAttribute(Attribute::NoAlias))
2446 continue;
2447
2448 // Make sure the call instruction is followed by an unconditional branch to
2449 // the return block.
2450 BasicBlock *CallBB = CI->getParent();
2451 BranchInst *BI = dyn_cast<BranchInst>(CallBB->getTerminator());
2452 if (!BI || !BI->isUnconditional() || BI->getSuccessor(0) != BB)
2453 continue;
2454
2455 // Duplicate the return into CallBB.
2456 (void)FoldReturnIntoUncondBranch(RetI, BB, CallBB);
2457 ModifiedDT = Changed = true;
2458 ++NumRetsDup;
2459 }
2460
2461 // If we eliminated all predecessors of the block, delete the block now.
2462 if (Changed && !BB->hasAddressTaken() && pred_begin(BB) == pred_end(BB))
2463 BB->eraseFromParent();
2464
2465 return Changed;
2466}
2467
2468//===----------------------------------------------------------------------===//
2469// Memory Optimization
2470//===----------------------------------------------------------------------===//
2471
2472namespace {
2473
2474/// This is an extended version of TargetLowering::AddrMode
2475/// which holds actual Value*'s for register values.
2476struct ExtAddrMode : public TargetLowering::AddrMode {
2477 Value *BaseReg;
2478 Value *ScaledReg;
2479 ExtAddrMode() : BaseReg(nullptr), ScaledReg(nullptr) {}
2480 void print(raw_ostream &OS) const;
2481 void dump() const;
2482
2483 bool operator==(const ExtAddrMode& O) const {
2484 return (BaseReg == O.BaseReg) && (ScaledReg == O.ScaledReg) &&
2485 (BaseGV == O.BaseGV) && (BaseOffs == O.BaseOffs) &&
2486 (HasBaseReg == O.HasBaseReg) && (Scale == O.Scale);
2487 }
2488};
2489
2490#ifndef NDEBUG
2491static inline raw_ostream &operator<<(raw_ostream &OS, const ExtAddrMode &AM) {
2492 AM.print(OS);
2493 return OS;
2494}
2495#endif
2496
2497void ExtAddrMode::print(raw_ostream &OS) const {
2498 bool NeedPlus = false;
2499 OS << "[";
2500 if (BaseGV) {
2501 OS << (NeedPlus ? " + " : "")
2502 << "GV:";
2503 BaseGV->printAsOperand(OS, /*PrintType=*/false);
2504 NeedPlus = true;
2505 }
2506
2507 if (BaseOffs) {
2508 OS << (NeedPlus ? " + " : "")
2509 << BaseOffs;
2510 NeedPlus = true;
2511 }
2512
2513 if (BaseReg) {
2514 OS << (NeedPlus ? " + " : "")
2515 << "Base:";
2516 BaseReg->printAsOperand(OS, /*PrintType=*/false);
2517 NeedPlus = true;
2518 }
2519 if (Scale) {
2520 OS << (NeedPlus ? " + " : "")
2521 << Scale << "*";
2522 ScaledReg->printAsOperand(OS, /*PrintType=*/false);
2523 }
2524
2525 OS << ']';
2526}
2527
2528#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
2529LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void ExtAddrMode::dump() const {
2530 print(dbgs());
2531 dbgs() << '\n';
2532}
2533#endif
2534
2535/// \brief This class provides transaction based operation on the IR.
2536/// Every change made through this class is recorded in the internal state and
2537/// can be undone (rollback) until commit is called.
2538class TypePromotionTransaction {
2539
2540 /// \brief This represents the common interface of the individual transaction.
2541 /// Each class implements the logic for doing one specific modification on
2542 /// the IR via the TypePromotionTransaction.
2543 class TypePromotionAction {
2544 protected:
2545 /// The Instruction modified.
2546 Instruction *Inst;
2547
2548 public:
2549 /// \brief Constructor of the action.
2550 /// The constructor performs the related action on the IR.
2551 TypePromotionAction(Instruction *Inst) : Inst(Inst) {}
2552
2553 virtual ~TypePromotionAction() {}
2554
2555 /// \brief Undo the modification done by this action.
2556 /// When this method is called, the IR must be in the same state as it was
2557 /// before this action was applied.
2558 /// \pre Undoing the action works if and only if the IR is in the exact same
2559 /// state as it was directly after this action was applied.
2560 virtual void undo() = 0;
2561
2562 /// \brief Advocate every change made by this action.
2563 /// When the results on the IR of the action are to be kept, it is important
2564 /// to call this function, otherwise hidden information may be kept forever.
2565 virtual void commit() {
2566 // Nothing to be done, this action is not doing anything.
2567 }
2568 };
2569
2570 /// \brief Utility to remember the position of an instruction.
2571 class InsertionHandler {
2572 /// Position of an instruction.
2573 /// Either an instruction:
2574 /// - Is the first in a basic block: BB is used.
2575 /// - Has a previous instructon: PrevInst is used.
2576 union {
2577 Instruction *PrevInst;
2578 BasicBlock *BB;
2579 } Point;
2580 /// Remember whether or not the instruction had a previous instruction.
2581 bool HasPrevInstruction;
2582
2583 public:
2584 /// \brief Record the position of \p Inst.
2585 InsertionHandler(Instruction *Inst) {
2586 BasicBlock::iterator It = Inst->getIterator();
2587 HasPrevInstruction = (It != (Inst->getParent()->begin()));
2588 if (HasPrevInstruction)
2589 Point.PrevInst = &*--It;
2590 else
2591 Point.BB = Inst->getParent();
2592 }
2593
2594 /// \brief Insert \p Inst at the recorded position.
2595 void insert(Instruction *Inst) {
2596 if (HasPrevInstruction) {
2597 if (Inst->getParent())
2598 Inst->removeFromParent();
2599 Inst->insertAfter(Point.PrevInst);
2600 } else {
2601 Instruction *Position = &*Point.BB->getFirstInsertionPt();
2602 if (Inst->getParent())
2603 Inst->moveBefore(Position);
2604 else
2605 Inst->insertBefore(Position);
2606 }
2607 }
2608 };
2609
2610 /// \brief Move an instruction before another.
2611 class InstructionMoveBefore : public TypePromotionAction {
2612 /// Original position of the instruction.
2613 InsertionHandler Position;
2614
2615 public:
2616 /// \brief Move \p Inst before \p Before.
2617 InstructionMoveBefore(Instruction *Inst, Instruction *Before)
2618 : TypePromotionAction(Inst), Position(Inst) {
2619 DEBUG(dbgs() << "Do: move: " << *Inst << "\nbefore: " << *Before << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: move: " << *
Inst << "\nbefore: " << *Before << "\n"; } }
while (false)
;
2620 Inst->moveBefore(Before);
2621 }
2622
2623 /// \brief Move the instruction back to its original position.
2624 void undo() override {
2625 DEBUG(dbgs() << "Undo: moveBefore: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: moveBefore: " <<
*Inst << "\n"; } } while (false)
;
2626 Position.insert(Inst);
2627 }
2628 };
2629
2630 /// \brief Set the operand of an instruction with a new value.
2631 class OperandSetter : public TypePromotionAction {
2632 /// Original operand of the instruction.
2633 Value *Origin;
2634 /// Index of the modified instruction.
2635 unsigned Idx;
2636
2637 public:
2638 /// \brief Set \p Idx operand of \p Inst with \p NewVal.
2639 OperandSetter(Instruction *Inst, unsigned Idx, Value *NewVal)
2640 : TypePromotionAction(Inst), Idx(Idx) {
2641 DEBUG(dbgs() << "Do: setOperand: " << Idx << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: setOperand: " <<
Idx << "\n" << "for:" << *Inst << "\n"
<< "with:" << *NewVal << "\n"; } } while (
false)
2642 << "for:" << *Inst << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: setOperand: " <<
Idx << "\n" << "for:" << *Inst << "\n"
<< "with:" << *NewVal << "\n"; } } while (
false)
2643 << "with:" << *NewVal << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: setOperand: " <<
Idx << "\n" << "for:" << *Inst << "\n"
<< "with:" << *NewVal << "\n"; } } while (
false)
;
2644 Origin = Inst->getOperand(Idx);
2645 Inst->setOperand(Idx, NewVal);
2646 }
2647
2648 /// \brief Restore the original value of the instruction.
2649 void undo() override {
2650 DEBUG(dbgs() << "Undo: setOperand:" << Idx << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: setOperand:" <<
Idx << "\n" << "for: " << *Inst << "\n"
<< "with: " << *Origin << "\n"; } } while (
false)
2651 << "for: " << *Inst << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: setOperand:" <<
Idx << "\n" << "for: " << *Inst << "\n"
<< "with: " << *Origin << "\n"; } } while (
false)
2652 << "with: " << *Origin << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: setOperand:" <<
Idx << "\n" << "for: " << *Inst << "\n"
<< "with: " << *Origin << "\n"; } } while (
false)
;
2653 Inst->setOperand(Idx, Origin);
2654 }
2655 };
2656
2657 /// \brief Hide the operands of an instruction.
2658 /// Do as if this instruction was not using any of its operands.
2659 class OperandsHider : public TypePromotionAction {
2660 /// The list of original operands.
2661 SmallVector<Value *, 4> OriginalValues;
2662
2663 public:
2664 /// \brief Remove \p Inst from the uses of the operands of \p Inst.
2665 OperandsHider(Instruction *Inst) : TypePromotionAction(Inst) {
2666 DEBUG(dbgs() << "Do: OperandsHider: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: OperandsHider: " <<
*Inst << "\n"; } } while (false)
;
2667 unsigned NumOpnds = Inst->getNumOperands();
2668 OriginalValues.reserve(NumOpnds);
2669 for (unsigned It = 0; It < NumOpnds; ++It) {
2670 // Save the current operand.
2671 Value *Val = Inst->getOperand(It);
2672 OriginalValues.push_back(Val);
2673 // Set a dummy one.
2674 // We could use OperandSetter here, but that would imply an overhead
2675 // that we are not willing to pay.
2676 Inst->setOperand(It, UndefValue::get(Val->getType()));
2677 }
2678 }
2679
2680 /// \brief Restore the original list of uses.
2681 void undo() override {
2682 DEBUG(dbgs() << "Undo: OperandsHider: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: OperandsHider: "
<< *Inst << "\n"; } } while (false)
;
2683 for (unsigned It = 0, EndIt = OriginalValues.size(); It != EndIt; ++It)
2684 Inst->setOperand(It, OriginalValues[It]);
2685 }
2686 };
2687
2688 /// \brief Build a truncate instruction.
2689 class TruncBuilder : public TypePromotionAction {
2690 Value *Val;
2691 public:
2692 /// \brief Build a truncate instruction of \p Opnd producing a \p Ty
2693 /// result.
2694 /// trunc Opnd to Ty.
2695 TruncBuilder(Instruction *Opnd, Type *Ty) : TypePromotionAction(Opnd) {
2696 IRBuilder<> Builder(Opnd);
2697 Val = Builder.CreateTrunc(Opnd, Ty, "promoted");
2698 DEBUG(dbgs() << "Do: TruncBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: TruncBuilder: " <<
*Val << "\n"; } } while (false)
;
2699 }
2700
2701 /// \brief Get the built value.
2702 Value *getBuiltValue() { return Val; }
2703
2704 /// \brief Remove the built instruction.
2705 void undo() override {
2706 DEBUG(dbgs() << "Undo: TruncBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: TruncBuilder: " <<
*Val << "\n"; } } while (false)
;
2707 if (Instruction *IVal = dyn_cast<Instruction>(Val))
2708 IVal->eraseFromParent();
2709 }
2710 };
2711
2712 /// \brief Build a sign extension instruction.
2713 class SExtBuilder : public TypePromotionAction {
2714 Value *Val;
2715 public:
2716 /// \brief Build a sign extension instruction of \p Opnd producing a \p Ty
2717 /// result.
2718 /// sext Opnd to Ty.
2719 SExtBuilder(Instruction *InsertPt, Value *Opnd, Type *Ty)
2720 : TypePromotionAction(InsertPt) {
2721 IRBuilder<> Builder(InsertPt);
2722 Val = Builder.CreateSExt(Opnd, Ty, "promoted");
2723 DEBUG(dbgs() << "Do: SExtBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: SExtBuilder: " <<
*Val << "\n"; } } while (false)
;
2724 }
2725
2726 /// \brief Get the built value.
2727 Value *getBuiltValue() { return Val; }
2728
2729 /// \brief Remove the built instruction.
2730 void undo() override {
2731 DEBUG(dbgs() << "Undo: SExtBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: SExtBuilder: " <<
*Val << "\n"; } } while (false)
;
2732 if (Instruction *IVal = dyn_cast<Instruction>(Val))
2733 IVal->eraseFromParent();
2734 }
2735 };
2736
2737 /// \brief Build a zero extension instruction.
2738 class ZExtBuilder : public TypePromotionAction {
2739 Value *Val;
2740 public:
2741 /// \brief Build a zero extension instruction of \p Opnd producing a \p Ty
2742 /// result.
2743 /// zext Opnd to Ty.
2744 ZExtBuilder(Instruction *InsertPt, Value *Opnd, Type *Ty)
2745 : TypePromotionAction(InsertPt) {
2746 IRBuilder<> Builder(InsertPt);
2747 Val = Builder.CreateZExt(Opnd, Ty, "promoted");
2748 DEBUG(dbgs() << "Do: ZExtBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: ZExtBuilder: " <<
*Val << "\n"; } } while (false)
;
2749 }
2750
2751 /// \brief Get the built value.
2752 Value *getBuiltValue() { return Val; }
2753
2754 /// \brief Remove the built instruction.
2755 void undo() override {
2756 DEBUG(dbgs() << "Undo: ZExtBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: ZExtBuilder: " <<
*Val << "\n"; } } while (false)
;
2757 if (Instruction *IVal = dyn_cast<Instruction>(Val))
2758 IVal->eraseFromParent();
2759 }
2760 };
2761
2762 /// \brief Mutate an instruction to another type.
2763 class TypeMutator : public TypePromotionAction {
2764 /// Record the original type.
2765 Type *OrigTy;
2766
2767 public:
2768 /// \brief Mutate the type of \p Inst into \p NewTy.
2769 TypeMutator(Instruction *Inst, Type *NewTy)
2770 : TypePromotionAction(Inst), OrigTy(Inst->getType()) {
2771 DEBUG(dbgs() << "Do: MutateType: " << *Inst << " with " << *NewTydo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: MutateType: " <<
*Inst << " with " << *NewTy << "\n"; } } while
(false)
2772 << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: MutateType: " <<
*Inst << " with " << *NewTy << "\n"; } } while
(false)
;
2773 Inst->mutateType(NewTy);
2774 }
2775
2776 /// \brief Mutate the instruction back to its original type.
2777 void undo() override {
2778 DEBUG(dbgs() << "Undo: MutateType: " << *Inst << " with " << *OrigTydo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: MutateType: " <<
*Inst << " with " << *OrigTy << "\n"; } } while
(false)
2779 << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: MutateType: " <<
*Inst << " with " << *OrigTy << "\n"; } } while
(false)
;
2780 Inst->mutateType(OrigTy);
2781 }
2782 };
2783
2784 /// \brief Replace the uses of an instruction by another instruction.
2785 class UsesReplacer : public TypePromotionAction {
2786 /// Helper structure to keep track of the replaced uses.
2787 struct InstructionAndIdx {
2788 /// The instruction using the instruction.
2789 Instruction *Inst;
2790 /// The index where this instruction is used for Inst.
2791 unsigned Idx;
2792 InstructionAndIdx(Instruction *Inst, unsigned Idx)
2793 : Inst(Inst), Idx(Idx) {}
2794 };
2795
2796 /// Keep track of the original uses (pair Instruction, Index).
2797 SmallVector<InstructionAndIdx, 4> OriginalUses;
2798 typedef SmallVectorImpl<InstructionAndIdx>::iterator use_iterator;
2799
2800 public:
2801 /// \brief Replace all the use of \p Inst by \p New.
2802 UsesReplacer(Instruction *Inst, Value *New) : TypePromotionAction(Inst) {
2803 DEBUG(dbgs() << "Do: UsersReplacer: " << *Inst << " with " << *Newdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: UsersReplacer: " <<
*Inst << " with " << *New << "\n"; } } while
(false)
2804 << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: UsersReplacer: " <<
*Inst << " with " << *New << "\n"; } } while
(false)
;
2805 // Record the original uses.
2806 for (Use &U : Inst->uses()) {
2807 Instruction *UserI = cast<Instruction>(U.getUser());
2808 OriginalUses.push_back(InstructionAndIdx(UserI, U.getOperandNo()));
2809 }
2810 // Now, we can replace the uses.
2811 Inst->replaceAllUsesWith(New);
2812 }
2813
2814 /// \brief Reassign the original uses of Inst to Inst.
2815 void undo() override {
2816 DEBUG(dbgs() << "Undo: UsersReplacer: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: UsersReplacer: "
<< *Inst << "\n"; } } while (false)
;
2817 for (use_iterator UseIt = OriginalUses.begin(),
2818 EndIt = OriginalUses.end();
2819 UseIt != EndIt; ++UseIt) {
2820 UseIt->Inst->setOperand(UseIt->Idx, Inst);
2821 }
2822 }
2823 };
2824
2825 /// \brief Remove an instruction from the IR.
2826 class InstructionRemover : public TypePromotionAction {
2827 /// Original position of the instruction.
2828 InsertionHandler Inserter;
2829 /// Helper structure to hide all the link to the instruction. In other
2830 /// words, this helps to do as if the instruction was removed.
2831 OperandsHider Hider;
2832 /// Keep track of the uses replaced, if any.
2833 UsesReplacer *Replacer;
2834 /// Keep track of instructions removed.
2835 SetOfInstrs &RemovedInsts;
2836
2837 public:
2838 /// \brief Remove all reference of \p Inst and optinally replace all its
2839 /// uses with New.
2840 /// \p RemovedInsts Keep track of the instructions removed by this Action.
2841 /// \pre If !Inst->use_empty(), then New != nullptr
2842 InstructionRemover(Instruction *Inst, SetOfInstrs &RemovedInsts,
2843 Value *New = nullptr)
2844 : TypePromotionAction(Inst), Inserter(Inst), Hider(Inst),
2845 Replacer(nullptr), RemovedInsts(RemovedInsts) {
2846 if (New)
2847 Replacer = new UsesReplacer(Inst, New);
2848 DEBUG(dbgs() << "Do: InstructionRemover: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: InstructionRemover: "
<< *Inst << "\n"; } } while (false)
;
2849 RemovedInsts.insert(Inst);
2850 /// The instructions removed here will be freed after completing
2851 /// optimizeBlock() for all blocks as we need to keep track of the
2852 /// removed instructions during promotion.
2853 Inst->removeFromParent();
2854 }
2855
2856 ~InstructionRemover() override { delete Replacer; }
2857
2858 /// \brief Resurrect the instruction and reassign it to the proper uses if
2859 /// new value was provided when build this action.
2860 void undo() override {
2861 DEBUG(dbgs() << "Undo: InstructionRemover: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: InstructionRemover: "
<< *Inst << "\n"; } } while (false)
;
2862 Inserter.insert(Inst);
2863 if (Replacer)
2864 Replacer->undo();
2865 Hider.undo();
2866 RemovedInsts.erase(Inst);
2867 }
2868 };
2869
2870public:
2871 /// Restoration point.
2872 /// The restoration point is a pointer to an action instead of an iterator
2873 /// because the iterator may be invalidated but not the pointer.
2874 typedef const TypePromotionAction *ConstRestorationPt;
2875
2876 TypePromotionTransaction(SetOfInstrs &RemovedInsts)
2877 : RemovedInsts(RemovedInsts) {}
2878
2879 /// Advocate every changes made in that transaction.
2880 void commit();
2881 /// Undo all the changes made after the given point.
2882 void rollback(ConstRestorationPt Point);
2883 /// Get the current restoration point.
2884 ConstRestorationPt getRestorationPoint() const;
2885
2886 /// \name API for IR modification with state keeping to support rollback.
2887 /// @{
2888 /// Same as Instruction::setOperand.
2889 void setOperand(Instruction *Inst, unsigned Idx, Value *NewVal);
2890 /// Same as Instruction::eraseFromParent.
2891 void eraseInstruction(Instruction *Inst, Value *NewVal = nullptr);
2892 /// Same as Value::replaceAllUsesWith.
2893 void replaceAllUsesWith(Instruction *Inst, Value *New);
2894 /// Same as Value::mutateType.
2895 void mutateType(Instruction *Inst, Type *NewTy);
2896 /// Same as IRBuilder::createTrunc.
2897 Value *createTrunc(Instruction *Opnd, Type *Ty);
2898 /// Same as IRBuilder::createSExt.
2899 Value *createSExt(Instruction *Inst, Value *Opnd, Type *Ty);
2900 /// Same as IRBuilder::createZExt.
2901 Value *createZExt(Instruction *Inst, Value *Opnd, Type *Ty);
2902 /// Same as Instruction::moveBefore.
2903 void moveBefore(Instruction *Inst, Instruction *Before);
2904 /// @}
2905
2906private:
2907 /// The ordered list of actions made so far.
2908 SmallVector<std::unique_ptr<TypePromotionAction>, 16> Actions;
2909 typedef SmallVectorImpl<std::unique_ptr<TypePromotionAction>>::iterator CommitPt;
2910 SetOfInstrs &RemovedInsts;
2911};
2912
2913void TypePromotionTransaction::setOperand(Instruction *Inst, unsigned Idx,
2914 Value *NewVal) {
2915 Actions.push_back(
2916 make_unique<TypePromotionTransaction::OperandSetter>(Inst, Idx, NewVal));
2917}
2918
2919void TypePromotionTransaction::eraseInstruction(Instruction *Inst,
2920 Value *NewVal) {
2921 Actions.push_back(
2922 make_unique<TypePromotionTransaction::InstructionRemover>(Inst,
2923 RemovedInsts, NewVal));
2924}
2925
2926void TypePromotionTransaction::replaceAllUsesWith(Instruction *Inst,
2927 Value *New) {
2928 Actions.push_back(make_unique<TypePromotionTransaction::UsesReplacer>(Inst, New));
2929}
2930
2931void TypePromotionTransaction::mutateType(Instruction *Inst, Type *NewTy) {
2932 Actions.push_back(make_unique<TypePromotionTransaction::TypeMutator>(Inst, NewTy));
2933}
2934
2935Value *TypePromotionTransaction::createTrunc(Instruction *Opnd,
2936 Type *Ty) {
2937 std::unique_ptr<TruncBuilder> Ptr(new TruncBuilder(Opnd, Ty));
2938 Value *Val = Ptr->getBuiltValue();
2939 Actions.push_back(std::move(Ptr));
2940 return Val;
2941}
2942
2943Value *TypePromotionTransaction::createSExt(Instruction *Inst,
2944 Value *Opnd, Type *Ty) {
2945 std::unique_ptr<SExtBuilder> Ptr(new SExtBuilder(Inst, Opnd, Ty));
2946 Value *Val = Ptr->getBuiltValue();
2947 Actions.push_back(std::move(Ptr));
2948 return Val;
2949}
2950
2951Value *TypePromotionTransaction::createZExt(Instruction *Inst,
2952 Value *Opnd, Type *Ty) {
2953 std::unique_ptr<ZExtBuilder> Ptr(new ZExtBuilder(Inst, Opnd, Ty));
2954 Value *Val = Ptr->getBuiltValue();
2955 Actions.push_back(std::move(Ptr));
2956 return Val;
2957}
2958
2959void TypePromotionTransaction::moveBefore(Instruction *Inst,
2960 Instruction *Before) {
2961 Actions.push_back(
2962 make_unique<TypePromotionTransaction::InstructionMoveBefore>(Inst, Before));
2963}
2964
2965TypePromotionTransaction::ConstRestorationPt
2966TypePromotionTransaction::getRestorationPoint() const {
2967 return !Actions.empty() ? Actions.back().get() : nullptr;
2968}
2969
2970void TypePromotionTransaction::commit() {
2971 for (CommitPt It = Actions.begin(), EndIt = Actions.end(); It != EndIt;
2972 ++It)
2973 (*It)->commit();
2974 Actions.clear();
2975}
2976
2977void TypePromotionTransaction::rollback(
2978 TypePromotionTransaction::ConstRestorationPt Point) {
2979 while (!Actions.empty() && Point != Actions.back().get()) {
2980 std::unique_ptr<TypePromotionAction> Curr = Actions.pop_back_val();
2981 Curr->undo();
2982 }
2983}
2984
2985/// \brief A helper class for matching addressing modes.
2986///
2987/// This encapsulates the logic for matching the target-legal addressing modes.
2988class AddressingModeMatcher {
2989 SmallVectorImpl<Instruction*> &AddrModeInsts;
2990 const TargetLowering &TLI;
2991 const TargetRegisterInfo &TRI;
2992 const DataLayout &DL;
2993
2994 /// AccessTy/MemoryInst - This is the type for the access (e.g. double) and
2995 /// the memory instruction that we're computing this address for.
2996 Type *AccessTy;
2997 unsigned AddrSpace;
2998 Instruction *MemoryInst;
2999
3000 /// This is the addressing mode that we're building up. This is
3001 /// part of the return value of this addressing mode matching stuff.
3002 ExtAddrMode &AddrMode;
3003
3004 /// The instructions inserted by other CodeGenPrepare optimizations.
3005 const SetOfInstrs &InsertedInsts;
3006 /// A map from the instructions to their type before promotion.
3007 InstrToOrigTy &PromotedInsts;
3008 /// The ongoing transaction where every action should be registered.
3009 TypePromotionTransaction &TPT;
3010
3011 /// This is set to true when we should not do profitability checks.
3012 /// When true, IsProfitableToFoldIntoAddressingMode always returns true.
3013 bool IgnoreProfitability;
3014
3015 AddressingModeMatcher(SmallVectorImpl<Instruction *> &AMI,
3016 const TargetLowering &TLI,
3017 const TargetRegisterInfo &TRI,
3018 Type *AT, unsigned AS,
3019 Instruction *MI, ExtAddrMode &AM,
3020 const SetOfInstrs &InsertedInsts,
3021 InstrToOrigTy &PromotedInsts,
3022 TypePromotionTransaction &TPT)
3023 : AddrModeInsts(AMI), TLI(TLI), TRI(TRI),
3024 DL(MI->getModule()->getDataLayout()), AccessTy(AT), AddrSpace(AS),
3025 MemoryInst(MI), AddrMode(AM), InsertedInsts(InsertedInsts),
3026 PromotedInsts(PromotedInsts), TPT(TPT) {
3027 IgnoreProfitability = false;
3028 }
3029public:
3030
3031 /// Find the maximal addressing mode that a load/store of V can fold,
3032 /// give an access type of AccessTy. This returns a list of involved
3033 /// instructions in AddrModeInsts.
3034 /// \p InsertedInsts The instructions inserted by other CodeGenPrepare
3035 /// optimizations.
3036 /// \p PromotedInsts maps the instructions to their type before promotion.
3037 /// \p The ongoing transaction where every action should be registered.
3038 static ExtAddrMode Match(Value *V, Type *AccessTy, unsigned AS,
3039 Instruction *MemoryInst,
3040 SmallVectorImpl<Instruction*> &AddrModeInsts,
3041 const TargetLowering &TLI,
3042 const TargetRegisterInfo &TRI,
3043 const SetOfInstrs &InsertedInsts,
3044 InstrToOrigTy &PromotedInsts,
3045 TypePromotionTransaction &TPT) {
3046 ExtAddrMode Result;
3047
3048 bool Success = AddressingModeMatcher(AddrModeInsts, TLI, TRI,
3049 AccessTy, AS,
3050 MemoryInst, Result, InsertedInsts,
3051 PromotedInsts, TPT).matchAddr(V, 0);
3052 (void)Success; assert(Success && "Couldn't select *anything*?")((Success && "Couldn't select *anything*?") ? static_cast
<void> (0) : __assert_fail ("Success && \"Couldn't select *anything*?\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 3052, __PRETTY_FUNCTION__))
;
3053 return Result;
3054 }
3055private:
3056 bool matchScaledValue(Value *ScaleReg, int64_t Scale, unsigned Depth);
3057 bool matchAddr(Value *V, unsigned Depth);
3058 bool matchOperationAddr(User *Operation, unsigned Opcode, unsigned Depth,
3059 bool *MovedAway = nullptr);
3060 bool isProfitableToFoldIntoAddressingMode(Instruction *I,
3061 ExtAddrMode &AMBefore,
3062 ExtAddrMode &AMAfter);
3063 bool valueAlreadyLiveAtInst(Value *Val, Value *KnownLive1, Value *KnownLive2);
3064 bool isPromotionProfitable(unsigned NewCost, unsigned OldCost,
3065 Value *PromotedOperand) const;
3066};
3067
3068/// Try adding ScaleReg*Scale to the current addressing mode.
3069/// Return true and update AddrMode if this addr mode is legal for the target,
3070/// false if not.
3071bool AddressingModeMatcher::matchScaledValue(Value *ScaleReg, int64_t Scale,
3072 unsigned Depth) {
3073 // If Scale is 1, then this is the same as adding ScaleReg to the addressing
3074 // mode. Just process that directly.
3075 if (Scale == 1)
3076 return matchAddr(ScaleReg, Depth);
3077
3078 // If the scale is 0, it takes nothing to add this.
3079 if (Scale == 0)
3080 return true;
3081
3082 // If we already have a scale of this value, we can add to it, otherwise, we
3083 // need an available scale field.
3084 if (AddrMode.Scale != 0 && AddrMode.ScaledReg != ScaleReg)
3085 return false;
3086
3087 ExtAddrMode TestAddrMode = AddrMode;
3088
3089 // Add scale to turn X*4+X*3 -> X*7. This could also do things like
3090 // [A+B + A*7] -> [B+A*8].
3091 TestAddrMode.Scale += Scale;
3092 TestAddrMode.ScaledReg = ScaleReg;
3093
3094 // If the new address isn't legal, bail out.
3095 if (!TLI.isLegalAddressingMode(DL, TestAddrMode, AccessTy, AddrSpace))
3096 return false;
3097
3098 // It was legal, so commit it.
3099 AddrMode = TestAddrMode;
3100
3101 // Okay, we decided that we can add ScaleReg+Scale to AddrMode. Check now
3102 // to see if ScaleReg is actually X+C. If so, we can turn this into adding
3103 // X*Scale + C*Scale to addr mode.
3104 ConstantInt *CI = nullptr; Value *AddLHS = nullptr;
3105 if (isa<Instruction>(ScaleReg) && // not a constant expr.
3106 match(ScaleReg, m_Add(m_Value(AddLHS), m_ConstantInt(CI)))) {
3107 TestAddrMode.ScaledReg = AddLHS;
3108 TestAddrMode.BaseOffs += CI->getSExtValue()*TestAddrMode.Scale;
3109
3110 // If this addressing mode is legal, commit it and remember that we folded
3111 // this instruction.
3112 if (TLI.isLegalAddressingMode(DL, TestAddrMode, AccessTy, AddrSpace)) {
3113 AddrModeInsts.push_back(cast<Instruction>(ScaleReg));
3114 AddrMode = TestAddrMode;
3115 return true;
3116 }
3117 }
3118
3119 // Otherwise, not (x+c)*scale, just return what we have.
3120 return true;
3121}
3122
3123/// This is a little filter, which returns true if an addressing computation
3124/// involving I might be folded into a load/store accessing it.
3125/// This doesn't need to be perfect, but needs to accept at least
3126/// the set of instructions that MatchOperationAddr can.
3127static bool MightBeFoldableInst(Instruction *I) {
3128 switch (I->getOpcode()) {
3129 case Instruction::BitCast:
3130 case Instruction::AddrSpaceCast:
3131 // Don't touch identity bitcasts.
3132 if (I->getType() == I->getOperand(0)->getType())
3133 return false;
3134 return I->getType()->isPointerTy() || I->getType()->isIntegerTy();
3135 case Instruction::PtrToInt:
3136 // PtrToInt is always a noop, as we know that the int type is pointer sized.
3137 return true;
3138 case Instruction::IntToPtr:
3139 // We know the input is intptr_t, so this is foldable.
3140 return true;
3141 case Instruction::Add:
3142 return true;
3143 case Instruction::Mul:
3144 case Instruction::Shl:
3145 // Can only handle X*C and X << C.
3146 return isa<ConstantInt>(I->getOperand(1));
3147 case Instruction::GetElementPtr:
3148 return true;
3149 default:
3150 return false;
3151 }
3152}
3153
3154/// \brief Check whether or not \p Val is a legal instruction for \p TLI.
3155/// \note \p Val is assumed to be the product of some type promotion.
3156/// Therefore if \p Val has an undefined state in \p TLI, this is assumed
3157/// to be legal, as the non-promoted value would have had the same state.
3158static bool isPromotedInstructionLegal(const TargetLowering &TLI,
3159 const DataLayout &DL, Value *Val) {
3160 Instruction *PromotedInst = dyn_cast<Instruction>(Val);
3161 if (!PromotedInst)
3162 return false;
3163 int ISDOpcode = TLI.InstructionOpcodeToISD(PromotedInst->getOpcode());
3164 // If the ISDOpcode is undefined, it was undefined before the promotion.
3165 if (!ISDOpcode)
3166 return true;
3167 // Otherwise, check if the promoted instruction is legal or not.
3168 return TLI.isOperationLegalOrCustom(
3169 ISDOpcode, TLI.getValueType(DL, PromotedInst->getType()));
3170}
3171
3172/// \brief Hepler class to perform type promotion.
3173class TypePromotionHelper {
3174 /// \brief Utility function to check whether or not a sign or zero extension
3175 /// of \p Inst with \p ConsideredExtType can be moved through \p Inst by
3176 /// either using the operands of \p Inst or promoting \p Inst.
3177 /// The type of the extension is defined by \p IsSExt.
3178 /// In other words, check if:
3179 /// ext (Ty Inst opnd1 opnd2 ... opndN) to ConsideredExtType.
3180 /// #1 Promotion applies:
3181 /// ConsideredExtType Inst (ext opnd1 to ConsideredExtType, ...).
3182 /// #2 Operand reuses:
3183 /// ext opnd1 to ConsideredExtType.
3184 /// \p PromotedInsts maps the instructions to their type before promotion.
3185 static bool canGetThrough(const Instruction *Inst, Type *ConsideredExtType,
3186 const InstrToOrigTy &PromotedInsts, bool IsSExt);
3187
3188 /// \brief Utility function to determine if \p OpIdx should be promoted when
3189 /// promoting \p Inst.
3190 static bool shouldExtOperand(const Instruction *Inst, int OpIdx) {
3191 return !(isa<SelectInst>(Inst) && OpIdx == 0);
3192 }
3193
3194 /// \brief Utility function to promote the operand of \p Ext when this
3195 /// operand is a promotable trunc or sext or zext.
3196 /// \p PromotedInsts maps the instructions to their type before promotion.
3197 /// \p CreatedInstsCost[out] contains the cost of all instructions
3198 /// created to promote the operand of Ext.
3199 /// Newly added extensions are inserted in \p Exts.
3200 /// Newly added truncates are inserted in \p Truncs.
3201 /// Should never be called directly.
3202 /// \return The promoted value which is used instead of Ext.
3203 static Value *promoteOperandForTruncAndAnyExt(
3204 Instruction *Ext, TypePromotionTransaction &TPT,
3205 InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
3206 SmallVectorImpl<Instruction *> *Exts,
3207 SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI);
3208
3209 /// \brief Utility function to promote the operand of \p Ext when this
3210 /// operand is promotable and is not a supported trunc or sext.
3211 /// \p PromotedInsts maps the instructions to their type before promotion.
3212 /// \p CreatedInstsCost[out] contains the cost of all the instructions
3213 /// created to promote the operand of Ext.
3214 /// Newly added extensions are inserted in \p Exts.
3215 /// Newly added truncates are inserted in \p Truncs.
3216 /// Should never be called directly.
3217 /// \return The promoted value which is used instead of Ext.
3218 static Value *promoteOperandForOther(Instruction *Ext,
3219 TypePromotionTransaction &TPT,
3220 InstrToOrigTy &PromotedInsts,
3221 unsigned &CreatedInstsCost,
3222 SmallVectorImpl<Instruction *> *Exts,
3223 SmallVectorImpl<Instruction *> *Truncs,
3224 const TargetLowering &TLI, bool IsSExt);
3225
3226 /// \see promoteOperandForOther.
3227 static Value *signExtendOperandForOther(
3228 Instruction *Ext, TypePromotionTransaction &TPT,
3229 InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
3230 SmallVectorImpl<Instruction *> *Exts,
3231 SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI) {
3232 return promoteOperandForOther(Ext, TPT, PromotedInsts, CreatedInstsCost,
3233 Exts, Truncs, TLI, true);
3234 }
3235
3236 /// \see promoteOperandForOther.
3237 static Value *zeroExtendOperandForOther(
3238 Instruction *Ext, TypePromotionTransaction &TPT,
3239 InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
3240 SmallVectorImpl<Instruction *> *Exts,
3241 SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI) {
3242 return promoteOperandForOther(Ext, TPT, PromotedInsts, CreatedInstsCost,
3243 Exts, Truncs, TLI, false);
3244 }
3245
3246public:
3247 /// Type for the utility function that promotes the operand of Ext.
3248 typedef Value *(*Action)(Instruction *Ext, TypePromotionTransaction &TPT,
3249 InstrToOrigTy &PromotedInsts,
3250 unsigned &CreatedInstsCost,
3251 SmallVectorImpl<Instruction *> *Exts,
3252 SmallVectorImpl<Instruction *> *Truncs,
3253 const TargetLowering &TLI);
3254 /// \brief Given a sign/zero extend instruction \p Ext, return the approriate
3255 /// action to promote the operand of \p Ext instead of using Ext.
3256 /// \return NULL if no promotable action is possible with the current
3257 /// sign extension.
3258 /// \p InsertedInsts keeps track of all the instructions inserted by the
3259 /// other CodeGenPrepare optimizations. This information is important
3260 /// because we do not want to promote these instructions as CodeGenPrepare
3261 /// will reinsert them later. Thus creating an infinite loop: create/remove.
3262 /// \p PromotedInsts maps the instructions to their type before promotion.
3263 static Action getAction(Instruction *Ext, const SetOfInstrs &InsertedInsts,
3264 const TargetLowering &TLI,
3265 const InstrToOrigTy &PromotedInsts);
3266};
3267
3268bool TypePromotionHelper::canGetThrough(const Instruction *Inst,
3269 Type *ConsideredExtType,
3270 const InstrToOrigTy &PromotedInsts,
3271 bool IsSExt) {
3272 // The promotion helper does not know how to deal with vector types yet.
3273 // To be able to fix that, we would need to fix the places where we
3274 // statically extend, e.g., constants and such.
3275 if (Inst->getType()->isVectorTy())
3276 return false;
3277
3278 // We can always get through zext.
3279 if (isa<ZExtInst>(Inst))
3280 return true;
3281
3282 // sext(sext) is ok too.
3283 if (IsSExt && isa<SExtInst>(Inst))
3284 return true;
3285
3286 // We can get through binary operator, if it is legal. In other words, the
3287 // binary operator must have a nuw or nsw flag.
3288 const BinaryOperator *BinOp = dyn_cast<BinaryOperator>(Inst);
3289 if (BinOp && isa<OverflowingBinaryOperator>(BinOp) &&
3290 ((!IsSExt && BinOp->hasNoUnsignedWrap()) ||
3291 (IsSExt && BinOp->hasNoSignedWrap())))
3292 return true;
3293
3294 // Check if we can do the following simplification.
3295 // ext(trunc(opnd)) --> ext(opnd)
3296 if (!isa<TruncInst>(Inst))
3297 return false;
3298
3299 Value *OpndVal = Inst->getOperand(0);
3300 // Check if we can use this operand in the extension.
3301 // If the type is larger than the result type of the extension, we cannot.
3302 if (!OpndVal->getType()->isIntegerTy() ||
3303 OpndVal->getType()->getIntegerBitWidth() >
3304 ConsideredExtType->getIntegerBitWidth())
3305 return false;
3306
3307 // If the operand of the truncate is not an instruction, we will not have
3308 // any information on the dropped bits.
3309 // (Actually we could for constant but it is not worth the extra logic).
3310 Instruction *Opnd = dyn_cast<Instruction>(OpndVal);
3311 if (!Opnd)
3312 return false;
3313
3314 // Check if the source of the type is narrow enough.
3315 // I.e., check that trunc just drops extended bits of the same kind of
3316 // the extension.
3317 // #1 get the type of the operand and check the kind of the extended bits.
3318 const Type *OpndType;
3319 InstrToOrigTy::const_iterator It = PromotedInsts.find(Opnd);
3320 if (It != PromotedInsts.end() && It->second.getInt() == IsSExt)
3321 OpndType = It->second.getPointer();
3322 else if ((IsSExt && isa<SExtInst>(Opnd)) || (!IsSExt && isa<ZExtInst>(Opnd)))
3323 OpndType = Opnd->getOperand(0)->getType();
3324 else
3325 return false;
3326
3327 // #2 check that the truncate just drops extended bits.
3328 return Inst->getType()->getIntegerBitWidth() >=
3329 OpndType->getIntegerBitWidth();
3330}
3331
3332TypePromotionHelper::Action TypePromotionHelper::getAction(
3333 Instruction *Ext, const SetOfInstrs &InsertedInsts,
3334 const TargetLowering &TLI, const InstrToOrigTy &PromotedInsts) {
3335 assert((isa<SExtInst>(Ext) || isa<ZExtInst>(Ext)) &&(((isa<SExtInst>(Ext) || isa<ZExtInst>(Ext)) &&
"Unexpected instruction type") ? static_cast<void> (0)
: __assert_fail ("(isa<SExtInst>(Ext) || isa<ZExtInst>(Ext)) && \"Unexpected instruction type\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 3336, __PRETTY_FUNCTION__))
3336 "Unexpected instruction type")(((isa<SExtInst>(Ext) || isa<ZExtInst>(Ext)) &&
"Unexpected instruction type") ? static_cast<void> (0)
: __assert_fail ("(isa<SExtInst>(Ext) || isa<ZExtInst>(Ext)) && \"Unexpected instruction type\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 3336, __PRETTY_FUNCTION__))
;
3337 Instruction *ExtOpnd = dyn_cast<Instruction>(Ext->getOperand(0));
3338 Type *ExtTy = Ext->getType();
3339 bool IsSExt = isa<SExtInst>(Ext);
3340 // If the operand of the extension is not an instruction, we cannot
3341 // get through.
3342 // If it, check we can get through.
3343 if (!ExtOpnd || !canGetThrough(ExtOpnd, ExtTy, PromotedInsts, IsSExt))
3344 return nullptr;
3345
3346 // Do not promote if the operand has been added by codegenprepare.
3347 // Otherwise, it means we are undoing an optimization that is likely to be
3348 // redone, thus causing potential infinite loop.
3349 if (isa<TruncInst>(ExtOpnd) && InsertedInsts.count(ExtOpnd))
3350 return nullptr;
3351
3352 // SExt or Trunc instructions.
3353 // Return the related handler.
3354 if (isa<SExtInst>(ExtOpnd) || isa<TruncInst>(ExtOpnd) ||
3355 isa<ZExtInst>(ExtOpnd))
3356 return promoteOperandForTruncAndAnyExt;
3357
3358 // Regular instruction.
3359 // Abort early if we will have to insert non-free instructions.
3360 if (!ExtOpnd->hasOneUse() && !TLI.isTruncateFree(ExtTy, ExtOpnd->getType()))
3361 return nullptr;
3362 return IsSExt ? signExtendOperandForOther : zeroExtendOperandForOther;
3363}
3364
3365Value *TypePromotionHelper::promoteOperandForTruncAndAnyExt(
3366 llvm::Instruction *SExt, TypePromotionTransaction &TPT,
3367 InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
3368 SmallVectorImpl<Instruction *> *Exts,
3369 SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI) {
3370 // By construction, the operand of SExt is an instruction. Otherwise we cannot
3371 // get through it and this method should not be called.
3372 Instruction *SExtOpnd = cast<Instruction>(SExt->getOperand(0));
3373 Value *ExtVal = SExt;
3374 bool HasMergedNonFreeExt = false;
3375 if (isa<ZExtInst>(SExtOpnd)) {
3376 // Replace s|zext(zext(opnd))
3377 // => zext(opnd).
3378 HasMergedNonFreeExt = !TLI.isExtFree(SExtOpnd);
3379 Value *ZExt =
3380 TPT.createZExt(SExt, SExtOpnd->getOperand(0), SExt->getType());
3381 TPT.replaceAllUsesWith(SExt, ZExt);
3382 TPT.eraseInstruction(SExt);
3383 ExtVal = ZExt;
3384 } else {
3385 // Replace z|sext(trunc(opnd)) or sext(sext(opnd))
3386 // => z|sext(opnd).
3387 TPT.setOperand(SExt, 0, SExtOpnd->getOperand(0));
3388 }
3389 CreatedInstsCost = 0;
3390
3391 // Remove dead code.
3392 if (SExtOpnd->use_empty())
3393 TPT.eraseInstruction(SExtOpnd);
3394
3395 // Check if the extension is still needed.
3396 Instruction *ExtInst = dyn_cast<Instruction>(ExtVal);
3397 if (!ExtInst || ExtInst->getType() != ExtInst->getOperand(0)->getType()) {
3398 if (ExtInst) {
3399 if (Exts)
3400 Exts->push_back(ExtInst);
3401 CreatedInstsCost = !TLI.isExtFree(ExtInst) && !HasMergedNonFreeExt;
3402 }
3403 return ExtVal;
3404 }
3405
3406 // At this point we have: ext ty opnd to ty.
3407 // Reassign the uses of ExtInst to the opnd and remove ExtInst.
3408 Value *NextVal = ExtInst->getOperand(0);
3409 TPT.eraseInstruction(ExtInst, NextVal);
3410 return NextVal;
3411}
3412
3413Value *TypePromotionHelper::promoteOperandForOther(
3414 Instruction *Ext, TypePromotionTransaction &TPT,
3415 InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
3416 SmallVectorImpl<Instruction *> *Exts,
3417 SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI,
3418 bool IsSExt) {
3419 // By construction, the operand of Ext is an instruction. Otherwise we cannot
3420 // get through it and this method should not be called.
3421 Instruction *ExtOpnd = cast<Instruction>(Ext->getOperand(0));
3422 CreatedInstsCost = 0;
3423 if (!ExtOpnd->hasOneUse()) {
3424 // ExtOpnd will be promoted.
3425 // All its uses, but Ext, will need to use a truncated value of the
3426 // promoted version.
3427 // Create the truncate now.
3428 Value *Trunc = TPT.createTrunc(Ext, ExtOpnd->getType());
3429 if (Instruction *ITrunc = dyn_cast<Instruction>(Trunc)) {
3430 ITrunc->removeFromParent();
3431 // Insert it just after the definition.
3432 ITrunc->insertAfter(ExtOpnd);
3433 if (Truncs)
3434 Truncs->push_back(ITrunc);
3435 }
3436
3437 TPT.replaceAllUsesWith(ExtOpnd, Trunc);
3438 // Restore the operand of Ext (which has been replaced by the previous call
3439 // to replaceAllUsesWith) to avoid creating a cycle trunc <-> sext.
3440 TPT.setOperand(Ext, 0, ExtOpnd);
3441 }
3442
3443 // Get through the Instruction:
3444 // 1. Update its type.
3445 // 2. Replace the uses of Ext by Inst.
3446 // 3. Extend each operand that needs to be extended.
3447
3448 // Remember the original type of the instruction before promotion.
3449 // This is useful to know that the high bits are sign extended bits.
3450 PromotedInsts.insert(std::pair<Instruction *, TypeIsSExt>(
3451 ExtOpnd, TypeIsSExt(ExtOpnd->getType(), IsSExt)));
3452 // Step #1.
3453 TPT.mutateType(ExtOpnd, Ext->getType());
3454 // Step #2.
3455 TPT.replaceAllUsesWith(Ext, ExtOpnd);
3456 // Step #3.
3457 Instruction *ExtForOpnd = Ext;
3458
3459 DEBUG(dbgs() << "Propagate Ext to operands\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Propagate Ext to operands\n"
; } } while (false)
;
3460 for (int OpIdx = 0, EndOpIdx = ExtOpnd->getNumOperands(); OpIdx != EndOpIdx;
3461 ++OpIdx) {
3462 DEBUG(dbgs() << "Operand:\n" << *(ExtOpnd->getOperand(OpIdx)) << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Operand:\n" << *
(ExtOpnd->getOperand(OpIdx)) << '\n'; } } while (false
)
;
3463 if (ExtOpnd->getOperand(OpIdx)->getType() == Ext->getType() ||
3464 !shouldExtOperand(ExtOpnd, OpIdx)) {
3465 DEBUG(dbgs() << "No need to propagate\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "No need to propagate\n"
; } } while (false)
;
3466 continue;
3467 }
3468 // Check if we can statically extend the operand.
3469 Value *Opnd = ExtOpnd->getOperand(OpIdx);
3470 if (const ConstantInt *Cst = dyn_cast<ConstantInt>(Opnd)) {
3471 DEBUG(dbgs() << "Statically extend\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Statically extend\n"; }
} while (false)
;
3472 unsigned BitWidth = Ext->getType()->getIntegerBitWidth();
3473 APInt CstVal = IsSExt ? Cst->getValue().sext(BitWidth)
3474 : Cst->getValue().zext(BitWidth);
3475 TPT.setOperand(ExtOpnd, OpIdx, ConstantInt::get(Ext->getType(), CstVal));
3476 continue;
3477 }
3478 // UndefValue are typed, so we have to statically sign extend them.
3479 if (isa<UndefValue>(Opnd)) {
3480 DEBUG(dbgs() << "Statically extend\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Statically extend\n"; }
} while (false)
;
3481 TPT.setOperand(ExtOpnd, OpIdx, UndefValue::get(Ext->getType()));
3482 continue;
3483 }
3484
3485 // Otherwise we have to explicity sign extend the operand.
3486 // Check if Ext was reused to extend an operand.
3487 if (!ExtForOpnd) {
3488 // If yes, create a new one.
3489 DEBUG(dbgs() << "More operands to ext\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "More operands to ext\n"
; } } while (false)
;
3490 Value *ValForExtOpnd = IsSExt ? TPT.createSExt(Ext, Opnd, Ext->getType())
3491 : TPT.createZExt(Ext, Opnd, Ext->getType());
3492 if (!isa<Instruction>(ValForExtOpnd)) {
3493 TPT.setOperand(ExtOpnd, OpIdx, ValForExtOpnd);
3494 continue;
3495 }
3496 ExtForOpnd = cast<Instruction>(ValForExtOpnd);
3497 }
3498 if (Exts)
3499 Exts->push_back(ExtForOpnd);
3500 TPT.setOperand(ExtForOpnd, 0, Opnd);
3501
3502 // Move the sign extension before the insertion point.
3503 TPT.moveBefore(ExtForOpnd, ExtOpnd);
3504 TPT.setOperand(ExtOpnd, OpIdx, ExtForOpnd);
3505 CreatedInstsCost += !TLI.isExtFree(ExtForOpnd);
3506 // If more sext are required, new instructions will have to be created.
3507 ExtForOpnd = nullptr;
3508 }
3509 if (ExtForOpnd == Ext) {
3510 DEBUG(dbgs() << "Extension is useless now\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Extension is useless now\n"
; } } while (false)
;
3511 TPT.eraseInstruction(Ext);
3512 }
3513 return ExtOpnd;
3514}
3515
3516/// Check whether or not promoting an instruction to a wider type is profitable.
3517/// \p NewCost gives the cost of extension instructions created by the
3518/// promotion.
3519/// \p OldCost gives the cost of extension instructions before the promotion
3520/// plus the number of instructions that have been
3521/// matched in the addressing mode the promotion.
3522/// \p PromotedOperand is the value that has been promoted.
3523/// \return True if the promotion is profitable, false otherwise.
3524bool AddressingModeMatcher::isPromotionProfitable(
3525 unsigned NewCost, unsigned OldCost, Value *PromotedOperand) const {
3526 DEBUG(dbgs() << "OldCost: " << OldCost << "\tNewCost: " << NewCost << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "OldCost: " << OldCost
<< "\tNewCost: " << NewCost << '\n'; } } while
(false)
;
3527 // The cost of the new extensions is greater than the cost of the
3528 // old extension plus what we folded.
3529 // This is not profitable.
3530 if (NewCost > OldCost)
3531 return false;
3532 if (NewCost < OldCost)
3533 return true;
3534 // The promotion is neutral but it may help folding the sign extension in
3535 // loads for instance.
3536 // Check that we did not create an illegal instruction.
3537 return isPromotedInstructionLegal(TLI, DL, PromotedOperand);
3538}
3539
3540/// Given an instruction or constant expr, see if we can fold the operation
3541/// into the addressing mode. If so, update the addressing mode and return
3542/// true, otherwise return false without modifying AddrMode.
3543/// If \p MovedAway is not NULL, it contains the information of whether or
3544/// not AddrInst has to be folded into the addressing mode on success.
3545/// If \p MovedAway == true, \p AddrInst will not be part of the addressing
3546/// because it has been moved away.
3547/// Thus AddrInst must not be added in the matched instructions.
3548/// This state can happen when AddrInst is a sext, since it may be moved away.
3549/// Therefore, AddrInst may not be valid when MovedAway is true and it must
3550/// not be referenced anymore.
3551bool AddressingModeMatcher::matchOperationAddr(User *AddrInst, unsigned Opcode,
3552 unsigned Depth,
3553 bool *MovedAway) {
3554 // Avoid exponential behavior on extremely deep expression trees.
3555 if (Depth >= 5) return false;
3556
3557 // By default, all matched instructions stay in place.
3558 if (MovedAway)
3559 *MovedAway = false;
3560
3561 switch (Opcode) {
3562 case Instruction::PtrToInt:
3563 // PtrToInt is always a noop, as we know that the int type is pointer sized.
3564 return matchAddr(AddrInst->getOperand(0), Depth);
3565 case Instruction::IntToPtr: {
3566 auto AS = AddrInst->getType()->getPointerAddressSpace();
3567 auto PtrTy = MVT::getIntegerVT(DL.getPointerSizeInBits(AS));
3568 // This inttoptr is a no-op if the integer type is pointer sized.
3569 if (TLI.getValueType(DL, AddrInst->getOperand(0)->getType()) == PtrTy)
3570 return matchAddr(AddrInst->getOperand(0), Depth);
3571 return false;
3572 }
3573 case Instruction::BitCast:
3574 // BitCast is always a noop, and we can handle it as long as it is
3575 // int->int or pointer->pointer (we don't want int<->fp or something).
3576 if ((AddrInst->getOperand(0)->getType()->isPointerTy() ||
3577 AddrInst->getOperand(0)->getType()->isIntegerTy()) &&
3578 // Don't touch identity bitcasts. These were probably put here by LSR,
3579 // and we don't want to mess around with them. Assume it knows what it
3580 // is doing.
3581 AddrInst->getOperand(0)->getType() != AddrInst->getType())
3582 return matchAddr(AddrInst->getOperand(0), Depth);
3583 return false;
3584 case Instruction::AddrSpaceCast: {
3585 unsigned SrcAS
3586 = AddrInst->getOperand(0)->getType()->getPointerAddressSpace();
3587 unsigned DestAS = AddrInst->getType()->getPointerAddressSpace();
3588 if (TLI.isNoopAddrSpaceCast(SrcAS, DestAS))
3589 return matchAddr(AddrInst->getOperand(0), Depth);
3590 return false;
3591 }
3592 case Instruction::Add: {
3593 // Check to see if we can merge in the RHS then the LHS. If so, we win.
3594 ExtAddrMode BackupAddrMode = AddrMode;
3595 unsigned OldSize = AddrModeInsts.size();
3596 // Start a transaction at this point.
3597 // The LHS may match but not the RHS.
3598 // Therefore, we need a higher level restoration point to undo partially
3599 // matched operation.
3600 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
3601 TPT.getRestorationPoint();
3602
3603 if (matchAddr(AddrInst->getOperand(1), Depth+1) &&
3604 matchAddr(AddrInst->getOperand(0), Depth+1))
3605 return true;
3606
3607 // Restore the old addr mode info.
3608 AddrMode = BackupAddrMode;
3609 AddrModeInsts.resize(OldSize);
3610 TPT.rollback(LastKnownGood);
3611
3612 // Otherwise this was over-aggressive. Try merging in the LHS then the RHS.
3613 if (matchAddr(AddrInst->getOperand(0), Depth+1) &&
3614 matchAddr(AddrInst->getOperand(1), Depth+1))
3615 return true;
3616
3617 // Otherwise we definitely can't merge the ADD in.
3618 AddrMode = BackupAddrMode;
3619 AddrModeInsts.resize(OldSize);
3620 TPT.rollback(LastKnownGood);
3621 break;
3622 }
3623 //case Instruction::Or:
3624 // TODO: We can handle "Or Val, Imm" iff this OR is equivalent to an ADD.
3625 //break;
3626 case Instruction::Mul:
3627 case Instruction::Shl: {
3628 // Can only handle X*C and X << C.
3629 ConstantInt *RHS = dyn_cast<ConstantInt>(AddrInst->getOperand(1));
3630 if (!RHS)
3631 return false;
3632 int64_t Scale = RHS->getSExtValue();
3633 if (Opcode == Instruction::Shl)
3634 Scale = 1LL << Scale;
3635
3636 return matchScaledValue(AddrInst->getOperand(0), Scale, Depth);
3637 }
3638 case Instruction::GetElementPtr: {
3639 // Scan the GEP. We check it if it contains constant offsets and at most
3640 // one variable offset.
3641 int VariableOperand = -1;
3642 unsigned VariableScale = 0;
3643
3644 int64_t ConstantOffset = 0;
3645 gep_type_iterator GTI = gep_type_begin(AddrInst);
3646 for (unsigned i = 1, e = AddrInst->getNumOperands(); i != e; ++i, ++GTI) {
3647 if (StructType *STy = GTI.getStructTypeOrNull()) {
3648 const StructLayout *SL = DL.getStructLayout(STy);
3649 unsigned Idx =
3650 cast<ConstantInt>(AddrInst->getOperand(i))->getZExtValue();
3651 ConstantOffset += SL->getElementOffset(Idx);
3652 } else {
3653 uint64_t TypeSize = DL.getTypeAllocSize(GTI.getIndexedType());
3654 if (ConstantInt *CI = dyn_cast<ConstantInt>(AddrInst->getOperand(i))) {
3655 ConstantOffset += CI->getSExtValue()*TypeSize;
3656 } else if (TypeSize) { // Scales of zero don't do anything.
3657 // We only allow one variable index at the moment.
3658 if (VariableOperand != -1)
3659 return false;
3660
3661 // Remember the variable index.
3662 VariableOperand = i;
3663 VariableScale = TypeSize;
3664 }
3665 }
3666 }
3667
3668 // A common case is for the GEP to only do a constant offset. In this case,
3669 // just add it to the disp field and check validity.
3670 if (VariableOperand == -1) {
3671 AddrMode.BaseOffs += ConstantOffset;
3672 if (ConstantOffset == 0 ||
3673 TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace)) {
3674 // Check to see if we can fold the base pointer in too.
3675 if (matchAddr(AddrInst->getOperand(0), Depth+1))
3676 return true;
3677 }
3678 AddrMode.BaseOffs -= ConstantOffset;
3679 return false;
3680 }
3681
3682 // Save the valid addressing mode in case we can't match.
3683 ExtAddrMode BackupAddrMode = AddrMode;
3684 unsigned OldSize = AddrModeInsts.size();
3685
3686 // See if the scale and offset amount is valid for this target.
3687 AddrMode.BaseOffs += ConstantOffset;
3688
3689 // Match the base operand of the GEP.
3690 if (!matchAddr(AddrInst->getOperand(0), Depth+1)) {
3691 // If it couldn't be matched, just stuff the value in a register.
3692 if (AddrMode.HasBaseReg) {
3693 AddrMode = BackupAddrMode;
3694 AddrModeInsts.resize(OldSize);
3695 return false;
3696 }
3697 AddrMode.HasBaseReg = true;
3698 AddrMode.BaseReg = AddrInst->getOperand(0);
3699 }
3700
3701 // Match the remaining variable portion of the GEP.
3702 if (!matchScaledValue(AddrInst->getOperand(VariableOperand), VariableScale,
3703 Depth)) {
3704 // If it couldn't be matched, try stuffing the base into a register
3705 // instead of matching it, and retrying the match of the scale.
3706 AddrMode = BackupAddrMode;
3707 AddrModeInsts.resize(OldSize);
3708 if (AddrMode.HasBaseReg)
3709 return false;
3710 AddrMode.HasBaseReg = true;
3711 AddrMode.BaseReg = AddrInst->getOperand(0);
3712 AddrMode.BaseOffs += ConstantOffset;
3713 if (!matchScaledValue(AddrInst->getOperand(VariableOperand),
3714 VariableScale, Depth)) {
3715 // If even that didn't work, bail.
3716 AddrMode = BackupAddrMode;
3717 AddrModeInsts.resize(OldSize);
3718 return false;
3719 }
3720 }
3721
3722 return true;
3723 }
3724 case Instruction::SExt:
3725 case Instruction::ZExt: {
3726 Instruction *Ext = dyn_cast<Instruction>(AddrInst);
3727 if (!Ext)
3728 return false;
3729
3730 // Try to move this ext out of the way of the addressing mode.
3731 // Ask for a method for doing so.
3732 TypePromotionHelper::Action TPH =
3733 TypePromotionHelper::getAction(Ext, InsertedInsts, TLI, PromotedInsts);
3734 if (!TPH)
3735 return false;
3736
3737 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
3738 TPT.getRestorationPoint();
3739 unsigned CreatedInstsCost = 0;
3740 unsigned ExtCost = !TLI.isExtFree(Ext);
3741 Value *PromotedOperand =
3742 TPH(Ext, TPT, PromotedInsts, CreatedInstsCost, nullptr, nullptr, TLI);
3743 // SExt has been moved away.
3744 // Thus either it will be rematched later in the recursive calls or it is
3745 // gone. Anyway, we must not fold it into the addressing mode at this point.
3746 // E.g.,
3747 // op = add opnd, 1
3748 // idx = ext op
3749 // addr = gep base, idx
3750 // is now:
3751 // promotedOpnd = ext opnd <- no match here
3752 // op = promoted_add promotedOpnd, 1 <- match (later in recursive calls)
3753 // addr = gep base, op <- match
3754 if (MovedAway)
3755 *MovedAway = true;
3756
3757 assert(PromotedOperand &&((PromotedOperand && "TypePromotionHelper should have filtered out those cases"
) ? static_cast<void> (0) : __assert_fail ("PromotedOperand && \"TypePromotionHelper should have filtered out those cases\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 3758, __PRETTY_FUNCTION__))
3758 "TypePromotionHelper should have filtered out those cases")((PromotedOperand && "TypePromotionHelper should have filtered out those cases"
) ? static_cast<void> (0) : __assert_fail ("PromotedOperand && \"TypePromotionHelper should have filtered out those cases\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 3758, __PRETTY_FUNCTION__))
;
3759
3760 ExtAddrMode BackupAddrMode = AddrMode;
3761 unsigned OldSize = AddrModeInsts.size();
3762
3763 if (!matchAddr(PromotedOperand, Depth) ||
3764 // The total of the new cost is equal to the cost of the created
3765 // instructions.
3766 // The total of the old cost is equal to the cost of the extension plus
3767 // what we have saved in the addressing mode.
3768 !isPromotionProfitable(CreatedInstsCost,
3769 ExtCost + (AddrModeInsts.size() - OldSize),
3770 PromotedOperand)) {
3771 AddrMode = BackupAddrMode;
3772 AddrModeInsts.resize(OldSize);
3773 DEBUG(dbgs() << "Sign extension does not pay off: rollback\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Sign extension does not pay off: rollback\n"
; } } while (false)
;
3774 TPT.rollback(LastKnownGood);
3775 return false;
3776 }
3777 return true;
3778 }
3779 }
3780 return false;
3781}
3782
3783/// If we can, try to add the value of 'Addr' into the current addressing mode.
3784/// If Addr can't be added to AddrMode this returns false and leaves AddrMode
3785/// unmodified. This assumes that Addr is either a pointer type or intptr_t
3786/// for the target.
3787///
3788bool AddressingModeMatcher::matchAddr(Value *Addr, unsigned Depth) {
3789 // Start a transaction at this point that we will rollback if the matching
3790 // fails.
3791 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
3792 TPT.getRestorationPoint();
3793 if (ConstantInt *CI = dyn_cast<ConstantInt>(Addr)) {
3794 // Fold in immediates if legal for the target.
3795 AddrMode.BaseOffs += CI->getSExtValue();
3796 if (TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace))
3797 return true;
3798 AddrMode.BaseOffs -= CI->getSExtValue();
3799 } else if (GlobalValue *GV = dyn_cast<GlobalValue>(Addr)) {
3800 // If this is a global variable, try to fold it into the addressing mode.
3801 if (!AddrMode.BaseGV) {
3802 AddrMode.BaseGV = GV;
3803 if (TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace))
3804 return true;
3805 AddrMode.BaseGV = nullptr;
3806 }
3807 } else if (Instruction *I = dyn_cast<Instruction>(Addr)) {
3808 ExtAddrMode BackupAddrMode = AddrMode;
3809 unsigned OldSize = AddrModeInsts.size();
3810
3811 // Check to see if it is possible to fold this operation.
3812 bool MovedAway = false;
3813 if (matchOperationAddr(I, I->getOpcode(), Depth, &MovedAway)) {
3814 // This instruction may have been moved away. If so, there is nothing
3815 // to check here.
3816 if (MovedAway)
3817 return true;
3818 // Okay, it's possible to fold this. Check to see if it is actually
3819 // *profitable* to do so. We use a simple cost model to avoid increasing
3820 // register pressure too much.
3821 if (I->hasOneUse() ||
3822 isProfitableToFoldIntoAddressingMode(I, BackupAddrMode, AddrMode)) {
3823 AddrModeInsts.push_back(I);
3824 return true;
3825 }
3826
3827 // It isn't profitable to do this, roll back.
3828 //cerr << "NOT FOLDING: " << *I;
3829 AddrMode = BackupAddrMode;
3830 AddrModeInsts.resize(OldSize);
3831 TPT.rollback(LastKnownGood);
3832 }
3833 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Addr)) {
3834 if (matchOperationAddr(CE, CE->getOpcode(), Depth))
3835 return true;
3836 TPT.rollback(LastKnownGood);
3837 } else if (isa<ConstantPointerNull>(Addr)) {
3838 // Null pointer gets folded without affecting the addressing mode.
3839 return true;
3840 }
3841
3842 // Worse case, the target should support [reg] addressing modes. :)
3843 if (!AddrMode.HasBaseReg) {
3844 AddrMode.HasBaseReg = true;
3845 AddrMode.BaseReg = Addr;
3846 // Still check for legality in case the target supports [imm] but not [i+r].
3847 if (TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace))
3848 return true;
3849 AddrMode.HasBaseReg = false;
3850 AddrMode.BaseReg = nullptr;
3851 }
3852
3853 // If the base register is already taken, see if we can do [r+r].
3854 if (AddrMode.Scale == 0) {
3855 AddrMode.Scale = 1;
3856 AddrMode.ScaledReg = Addr;
3857 if (TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace))
3858 return true;
3859 AddrMode.Scale = 0;
3860 AddrMode.ScaledReg = nullptr;
3861 }
3862 // Couldn't match.
3863 TPT.rollback(LastKnownGood);
3864 return false;
3865}
3866
3867/// Check to see if all uses of OpVal by the specified inline asm call are due
3868/// to memory operands. If so, return true, otherwise return false.
3869static bool IsOperandAMemoryOperand(CallInst *CI, InlineAsm *IA, Value *OpVal,
3870 const TargetLowering &TLI,
3871 const TargetRegisterInfo &TRI) {
3872 const Function *F = CI->getParent()->getParent();
3873 TargetLowering::AsmOperandInfoVector TargetConstraints =
3874 TLI.ParseConstraints(F->getParent()->getDataLayout(), &TRI,
3875 ImmutableCallSite(CI));
3876
3877 for (unsigned i = 0, e = TargetConstraints.size(); i != e; ++i) {
3878 TargetLowering::AsmOperandInfo &OpInfo = TargetConstraints[i];
3879
3880 // Compute the constraint code and ConstraintType to use.
3881 TLI.ComputeConstraintToUse(OpInfo, SDValue());
3882
3883 // If this asm operand is our Value*, and if it isn't an indirect memory
3884 // operand, we can't fold it!
3885 if (OpInfo.CallOperandVal == OpVal &&
3886 (OpInfo.ConstraintType != TargetLowering::C_Memory ||
3887 !OpInfo.isIndirect))
3888 return false;
3889 }
3890
3891 return true;
3892}
3893
3894/// Recursively walk all the uses of I until we find a memory use.
3895/// If we find an obviously non-foldable instruction, return true.
3896/// Add the ultimately found memory instructions to MemoryUses.
3897static bool FindAllMemoryUses(
3898 Instruction *I,
3899 SmallVectorImpl<std::pair<Instruction *, unsigned>> &MemoryUses,
3900 SmallPtrSetImpl<Instruction *> &ConsideredInsts,
3901 const TargetLowering &TLI, const TargetRegisterInfo &TRI) {
3902 // If we already considered this instruction, we're done.
3903 if (!ConsideredInsts.insert(I).second)
3904 return false;
3905
3906 // If this is an obviously unfoldable instruction, bail out.
3907 if (!MightBeFoldableInst(I))
3908 return true;
3909
3910 const bool OptSize = I->getFunction()->optForSize();
3911
3912 // Loop over all the uses, recursively processing them.
3913 for (Use &U : I->uses()) {
3914 Instruction *UserI = cast<Instruction>(U.getUser());
3915
3916 if (LoadInst *LI = dyn_cast<LoadInst>(UserI)) {
3917 MemoryUses.push_back(std::make_pair(LI, U.getOperandNo()));
3918 continue;
3919 }
3920
3921 if (StoreInst *SI = dyn_cast<StoreInst>(UserI)) {
3922 unsigned opNo = U.getOperandNo();
3923 if (opNo != StoreInst::getPointerOperandIndex())
3924 return true; // Storing addr, not into addr.
3925 MemoryUses.push_back(std::make_pair(SI, opNo));
3926 continue;
3927 }
3928
3929 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(UserI)) {
3930 unsigned opNo = U.getOperandNo();
3931 if (opNo != AtomicRMWInst::getPointerOperandIndex())
3932 return true; // Storing addr, not into addr.
3933 MemoryUses.push_back(std::make_pair(RMW, opNo));
3934 continue;
3935 }
3936
3937 if (AtomicCmpXchgInst *CmpX = dyn_cast<AtomicCmpXchgInst>(UserI)) {
3938 unsigned opNo = U.getOperandNo();
3939 if (opNo != AtomicCmpXchgInst::getPointerOperandIndex())
3940 return true; // Storing addr, not into addr.
3941 MemoryUses.push_back(std::make_pair(CmpX, opNo));
3942 continue;
3943 }
3944
3945 if (CallInst *CI = dyn_cast<CallInst>(UserI)) {
3946 // If this is a cold call, we can sink the addressing calculation into
3947 // the cold path. See optimizeCallInst
3948 if (!OptSize && CI->hasFnAttr(Attribute::Cold))
3949 continue;
3950
3951 InlineAsm *IA = dyn_cast<InlineAsm>(CI->getCalledValue());
3952 if (!IA) return true;
3953
3954 // If this is a memory operand, we're cool, otherwise bail out.
3955 if (!IsOperandAMemoryOperand(CI, IA, I, TLI, TRI))
3956 return true;
3957 continue;
3958 }
3959
3960 if (FindAllMemoryUses(UserI, MemoryUses, ConsideredInsts, TLI, TRI))
3961 return true;
3962 }
3963
3964 return false;
3965}
3966
3967/// Return true if Val is already known to be live at the use site that we're
3968/// folding it into. If so, there is no cost to include it in the addressing
3969/// mode. KnownLive1 and KnownLive2 are two values that we know are live at the
3970/// instruction already.
3971bool AddressingModeMatcher::valueAlreadyLiveAtInst(Value *Val,Value *KnownLive1,
3972 Value *KnownLive2) {
3973 // If Val is either of the known-live values, we know it is live!
3974 if (Val == nullptr || Val == KnownLive1 || Val == KnownLive2)
3975 return true;
3976
3977 // All values other than instructions and arguments (e.g. constants) are live.
3978 if (!isa<Instruction>(Val) && !isa<Argument>(Val)) return true;
3979
3980 // If Val is a constant sized alloca in the entry block, it is live, this is
3981 // true because it is just a reference to the stack/frame pointer, which is
3982 // live for the whole function.
3983 if (AllocaInst *AI = dyn_cast<AllocaInst>(Val))
3984 if (AI->isStaticAlloca())
3985 return true;
3986
3987 // Check to see if this value is already used in the memory instruction's
3988 // block. If so, it's already live into the block at the very least, so we
3989 // can reasonably fold it.
3990 return Val->isUsedInBasicBlock(MemoryInst->getParent());
3991}
3992
3993/// It is possible for the addressing mode of the machine to fold the specified
3994/// instruction into a load or store that ultimately uses it.
3995/// However, the specified instruction has multiple uses.
3996/// Given this, it may actually increase register pressure to fold it
3997/// into the load. For example, consider this code:
3998///
3999/// X = ...
4000/// Y = X+1
4001/// use(Y) -> nonload/store
4002/// Z = Y+1
4003/// load Z
4004///
4005/// In this case, Y has multiple uses, and can be folded into the load of Z
4006/// (yielding load [X+2]). However, doing this will cause both "X" and "X+1" to
4007/// be live at the use(Y) line. If we don't fold Y into load Z, we use one
4008/// fewer register. Since Y can't be folded into "use(Y)" we don't increase the
4009/// number of computations either.
4010///
4011/// Note that this (like most of CodeGenPrepare) is just a rough heuristic. If
4012/// X was live across 'load Z' for other reasons, we actually *would* want to
4013/// fold the addressing mode in the Z case. This would make Y die earlier.
4014bool AddressingModeMatcher::
4015isProfitableToFoldIntoAddressingMode(Instruction *I, ExtAddrMode &AMBefore,
4016 ExtAddrMode &AMAfter) {
4017 if (IgnoreProfitability) return true;
4018
4019 // AMBefore is the addressing mode before this instruction was folded into it,
4020 // and AMAfter is the addressing mode after the instruction was folded. Get
4021 // the set of registers referenced by AMAfter and subtract out those
4022 // referenced by AMBefore: this is the set of values which folding in this
4023 // address extends the lifetime of.
4024 //
4025 // Note that there are only two potential values being referenced here,
4026 // BaseReg and ScaleReg (global addresses are always available, as are any
4027 // folded immediates).
4028 Value *BaseReg = AMAfter.BaseReg, *ScaledReg = AMAfter.ScaledReg;
4029
4030 // If the BaseReg or ScaledReg was referenced by the previous addrmode, their
4031 // lifetime wasn't extended by adding this instruction.
4032 if (valueAlreadyLiveAtInst(BaseReg, AMBefore.BaseReg, AMBefore.ScaledReg))
4033 BaseReg = nullptr;
4034 if (valueAlreadyLiveAtInst(ScaledReg, AMBefore.BaseReg, AMBefore.ScaledReg))
4035 ScaledReg = nullptr;
4036
4037 // If folding this instruction (and it's subexprs) didn't extend any live
4038 // ranges, we're ok with it.
4039 if (!BaseReg && !ScaledReg)
4040 return true;
4041
4042 // If all uses of this instruction can have the address mode sunk into them,
4043 // we can remove the addressing mode and effectively trade one live register
4044 // for another (at worst.) In this context, folding an addressing mode into
4045 // the use is just a particularly nice way of sinking it.
4046 SmallVector<std::pair<Instruction*,unsigned>, 16> MemoryUses;
4047 SmallPtrSet<Instruction*, 16> ConsideredInsts;
4048 if (FindAllMemoryUses(I, MemoryUses, ConsideredInsts, TLI, TRI))
4049 return false; // Has a non-memory, non-foldable use!
4050
4051 // Now that we know that all uses of this instruction are part of a chain of
4052 // computation involving only operations that could theoretically be folded
4053 // into a memory use, loop over each of these memory operation uses and see
4054 // if they could *actually* fold the instruction. The assumption is that
4055 // addressing modes are cheap and that duplicating the computation involved
4056 // many times is worthwhile, even on a fastpath. For sinking candidates
4057 // (i.e. cold call sites), this serves as a way to prevent excessive code
4058 // growth since most architectures have some reasonable small and fast way to
4059 // compute an effective address. (i.e LEA on x86)
4060 SmallVector<Instruction*, 32> MatchedAddrModeInsts;
4061 for (unsigned i = 0, e = MemoryUses.size(); i != e; ++i) {
4062 Instruction *User = MemoryUses[i].first;
4063 unsigned OpNo = MemoryUses[i].second;
4064
4065 // Get the access type of this use. If the use isn't a pointer, we don't
4066 // know what it accesses.
4067 Value *Address = User->getOperand(OpNo);
4068 PointerType *AddrTy = dyn_cast<PointerType>(Address->getType());
4069 if (!AddrTy)
4070 return false;
4071 Type *AddressAccessTy = AddrTy->getElementType();
4072 unsigned AS = AddrTy->getAddressSpace();
4073
4074 // Do a match against the root of this address, ignoring profitability. This
4075 // will tell us if the addressing mode for the memory operation will
4076 // *actually* cover the shared instruction.
4077 ExtAddrMode Result;
4078 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
4079 TPT.getRestorationPoint();
4080 AddressingModeMatcher Matcher(MatchedAddrModeInsts, TLI, TRI,
4081 AddressAccessTy, AS,
4082 MemoryInst, Result, InsertedInsts,
4083 PromotedInsts, TPT);
4084 Matcher.IgnoreProfitability = true;
4085 bool Success = Matcher.matchAddr(Address, 0);
4086 (void)Success; assert(Success && "Couldn't select *anything*?")((Success && "Couldn't select *anything*?") ? static_cast
<void> (0) : __assert_fail ("Success && \"Couldn't select *anything*?\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 4086, __PRETTY_FUNCTION__))
;
4087
4088 // The match was to check the profitability, the changes made are not
4089 // part of the original matcher. Therefore, they should be dropped
4090 // otherwise the original matcher will not present the right state.
4091 TPT.rollback(LastKnownGood);
4092
4093 // If the match didn't cover I, then it won't be shared by it.
4094 if (!is_contained(MatchedAddrModeInsts, I))
4095 return false;
4096
4097 MatchedAddrModeInsts.clear();
4098 }
4099
4100 return true;
4101}
4102
4103} // end anonymous namespace
4104
4105/// Return true if the specified values are defined in a
4106/// different basic block than BB.
4107static bool IsNonLocalValue(Value *V, BasicBlock *BB) {
4108 if (Instruction *I = dyn_cast<Instruction>(V))
4109 return I->getParent() != BB;
4110 return false;
4111}
4112
4113/// Sink addressing mode computation immediate before MemoryInst if doing so
4114/// can be done without increasing register pressure. The need for the
4115/// register pressure constraint means this can end up being an all or nothing
4116/// decision for all uses of the same addressing computation.
4117///
4118/// Load and Store Instructions often have addressing modes that can do
4119/// significant amounts of computation. As such, instruction selection will try
4120/// to get the load or store to do as much computation as possible for the
4121/// program. The problem is that isel can only see within a single block. As
4122/// such, we sink as much legal addressing mode work into the block as possible.
4123///
4124/// This method is used to optimize both load/store and inline asms with memory
4125/// operands. It's also used to sink addressing computations feeding into cold
4126/// call sites into their (cold) basic block.
4127///
4128/// The motivation for handling sinking into cold blocks is that doing so can
4129/// both enable other address mode sinking (by satisfying the register pressure
4130/// constraint above), and reduce register pressure globally (by removing the
4131/// addressing mode computation from the fast path entirely.).
4132bool CodeGenPrepare::optimizeMemoryInst(Instruction *MemoryInst, Value *Addr,
4133 Type *AccessTy, unsigned AddrSpace) {
4134 Value *Repl = Addr;
4135
4136 // Try to collapse single-value PHI nodes. This is necessary to undo
4137 // unprofitable PRE transformations.
4138 SmallVector<Value*, 8> worklist;
4139 SmallPtrSet<Value*, 16> Visited;
4140 worklist.push_back(Addr);
4141
4142 // Use a worklist to iteratively look through PHI nodes, and ensure that
4143 // the addressing mode obtained from the non-PHI roots of the graph
4144 // are equivalent.
4145 Value *Consensus = nullptr;
4146 unsigned NumUsesConsensus = 0;
4147 bool IsNumUsesConsensusValid = false;
4148 SmallVector<Instruction*, 16> AddrModeInsts;
4149 ExtAddrMode AddrMode;
4150 TypePromotionTransaction TPT(RemovedInsts);
4151 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
4152 TPT.getRestorationPoint();
4153 while (!worklist.empty()) {
4154 Value *V = worklist.back();
4155 worklist.pop_back();
4156
4157 // Break use-def graph loops.
4158 if (!Visited.insert(V).second) {
4159 Consensus = nullptr;
4160 break;
4161 }
4162
4163 // For a PHI node, push all of its incoming values.
4164 if (PHINode *P = dyn_cast<PHINode>(V)) {
4165 for (Value *IncValue : P->incoming_values())
4166 worklist.push_back(IncValue);
4167 continue;
4168 }
4169
4170 // For non-PHIs, determine the addressing mode being computed. Note that
4171 // the result may differ depending on what other uses our candidate
4172 // addressing instructions might have.
4173 SmallVector<Instruction*, 16> NewAddrModeInsts;
4174 ExtAddrMode NewAddrMode = AddressingModeMatcher::Match(
4175 V, AccessTy, AddrSpace, MemoryInst, NewAddrModeInsts, *TLI, *TRI,
4176 InsertedInsts, PromotedInsts, TPT);
4177
4178 // This check is broken into two cases with very similar code to avoid using
4179 // getNumUses() as much as possible. Some values have a lot of uses, so
4180 // calling getNumUses() unconditionally caused a significant compile-time
4181 // regression.
4182 if (!Consensus) {
4183 Consensus = V;
4184 AddrMode = NewAddrMode;
4185 AddrModeInsts = NewAddrModeInsts;
4186 continue;
4187 } else if (NewAddrMode == AddrMode) {
4188 if (!IsNumUsesConsensusValid) {
4189 NumUsesConsensus = Consensus->getNumUses();
4190 IsNumUsesConsensusValid = true;
4191 }
4192
4193 // Ensure that the obtained addressing mode is equivalent to that obtained
4194 // for all other roots of the PHI traversal. Also, when choosing one
4195 // such root as representative, select the one with the most uses in order
4196 // to keep the cost modeling heuristics in AddressingModeMatcher
4197 // applicable.
4198 unsigned NumUses = V->getNumUses();
4199 if (NumUses > NumUsesConsensus) {
4200 Consensus = V;
4201 NumUsesConsensus = NumUses;
4202 AddrModeInsts = NewAddrModeInsts;
4203 }
4204 continue;
4205 }
4206
4207 Consensus = nullptr;
4208 break;
4209 }
4210
4211 // If the addressing mode couldn't be determined, or if multiple different
4212 // ones were determined, bail out now.
4213 if (!Consensus) {
4214 TPT.rollback(LastKnownGood);
4215 return false;
4216 }
4217 TPT.commit();
4218
4219 // If all the instructions matched are already in this BB, don't do anything.
4220 if (none_of(AddrModeInsts, [&](Value *V) {
4221 return IsNonLocalValue(V, MemoryInst->getParent());
4222 })) {
4223 DEBUG(dbgs() << "CGP: Found local addrmode: " << AddrMode << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: Found local addrmode: "
<< AddrMode << "\n"; } } while (false)
;
4224 return false;
4225 }
4226
4227 // Insert this computation right after this user. Since our caller is
4228 // scanning from the top of the BB to the bottom, reuse of the expr are
4229 // guaranteed to happen later.
4230 IRBuilder<> Builder(MemoryInst);
4231
4232 // Now that we determined the addressing expression we want to use and know
4233 // that we have to sink it into this block. Check to see if we have already
4234 // done this for some other load/store instr in this block. If so, reuse the
4235 // computation.
4236 Value *&SunkAddr = SunkAddrs[Addr];
4237 if (SunkAddr) {
4238 DEBUG(dbgs() << "CGP: Reusing nonlocal addrmode: " << AddrMode << " for "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: Reusing nonlocal addrmode: "
<< AddrMode << " for " << *MemoryInst <<
"\n"; } } while (false)
4239 << *MemoryInst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: Reusing nonlocal addrmode: "
<< AddrMode << " for " << *MemoryInst <<
"\n"; } } while (false)
;
4240 if (SunkAddr->getType() != Addr->getType())
4241 SunkAddr = Builder.CreatePointerCast(SunkAddr, Addr->getType());
4242 } else if (AddrSinkUsingGEPs ||
4243 (!AddrSinkUsingGEPs.getNumOccurrences() && TM &&
4244 SubtargetInfo->useAA())) {
4245 // By default, we use the GEP-based method when AA is used later. This
4246 // prevents new inttoptr/ptrtoint pairs from degrading AA capabilities.
4247 DEBUG(dbgs() << "CGP: SINKING nonlocal addrmode: " << AddrMode << " for "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: SINKING nonlocal addrmode: "
<< AddrMode << " for " << *MemoryInst <<
"\n"; } } while (false)
4248 << *MemoryInst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: SINKING nonlocal addrmode: "
<< AddrMode << " for " << *MemoryInst <<
"\n"; } } while (false)
;
4249 Type *IntPtrTy = DL->getIntPtrType(Addr->getType());
4250 Value *ResultPtr = nullptr, *ResultIndex = nullptr;
4251
4252 // First, find the pointer.
4253 if (AddrMode.BaseReg && AddrMode.BaseReg->getType()->isPointerTy()) {
4254 ResultPtr = AddrMode.BaseReg;
4255 AddrMode.BaseReg = nullptr;
4256 }
4257
4258 if (AddrMode.Scale && AddrMode.ScaledReg->getType()->isPointerTy()) {
4259 // We can't add more than one pointer together, nor can we scale a
4260 // pointer (both of which seem meaningless).
4261 if (ResultPtr || AddrMode.Scale != 1)
4262 return false;
4263
4264 ResultPtr = AddrMode.ScaledReg;
4265 AddrMode.Scale = 0;
4266 }
4267
4268 if (AddrMode.BaseGV) {
4269 if (ResultPtr)
4270 return false;
4271
4272 ResultPtr = AddrMode.BaseGV;
4273 }
4274
4275 // If the real base value actually came from an inttoptr, then the matcher
4276 // will look through it and provide only the integer value. In that case,
4277 // use it here.
4278 if (!ResultPtr && AddrMode.BaseReg) {
4279 ResultPtr =
4280 Builder.CreateIntToPtr(AddrMode.BaseReg, Addr->getType(), "sunkaddr");
4281 AddrMode.BaseReg = nullptr;
4282 } else if (!ResultPtr && AddrMode.Scale == 1) {
4283 ResultPtr =
4284 Builder.CreateIntToPtr(AddrMode.ScaledReg, Addr->getType(), "sunkaddr");
4285 AddrMode.Scale = 0;
4286 }
4287
4288 if (!ResultPtr &&
4289 !AddrMode.BaseReg && !AddrMode.Scale && !AddrMode.BaseOffs) {
4290 SunkAddr = Constant::getNullValue(Addr->getType());
4291 } else if (!ResultPtr) {
4292 return false;
4293 } else {
4294 Type *I8PtrTy =
4295 Builder.getInt8PtrTy(Addr->getType()->getPointerAddressSpace());
4296 Type *I8Ty = Builder.getInt8Ty();
4297
4298 // Start with the base register. Do this first so that subsequent address
4299 // matching finds it last, which will prevent it from trying to match it
4300 // as the scaled value in case it happens to be a mul. That would be
4301 // problematic if we've sunk a different mul for the scale, because then
4302 // we'd end up sinking both muls.
4303 if (AddrMode.BaseReg) {
4304 Value *V = AddrMode.BaseReg;
4305 if (V->getType() != IntPtrTy)
4306 V = Builder.CreateIntCast(V, IntPtrTy, /*isSigned=*/true, "sunkaddr");
4307
4308 ResultIndex = V;
4309 }
4310
4311 // Add the scale value.
4312 if (AddrMode.Scale) {
4313 Value *V = AddrMode.ScaledReg;
4314 if (V->getType() == IntPtrTy) {
4315 // done.
4316 } else if (cast<IntegerType>(IntPtrTy)->getBitWidth() <
4317 cast<IntegerType>(V->getType())->getBitWidth()) {
4318 V = Builder.CreateTrunc(V, IntPtrTy, "sunkaddr");
4319 } else {
4320 // It is only safe to sign extend the BaseReg if we know that the math
4321 // required to create it did not overflow before we extend it. Since
4322 // the original IR value was tossed in favor of a constant back when
4323 // the AddrMode was created we need to bail out gracefully if widths
4324 // do not match instead of extending it.
4325 Instruction *I = dyn_cast_or_null<Instruction>(ResultIndex);
4326 if (I && (ResultIndex != AddrMode.BaseReg))
4327 I->eraseFromParent();
4328 return false;
4329 }
4330
4331 if (AddrMode.Scale != 1)
4332 V = Builder.CreateMul(V, ConstantInt::get(IntPtrTy, AddrMode.Scale),
4333 "sunkaddr");
4334 if (ResultIndex)
4335 ResultIndex = Builder.CreateAdd(ResultIndex, V, "sunkaddr");
4336 else
4337 ResultIndex = V;
4338 }
4339
4340 // Add in the Base Offset if present.
4341 if (AddrMode.BaseOffs) {
4342 Value *V = ConstantInt::get(IntPtrTy, AddrMode.BaseOffs);
4343 if (ResultIndex) {
4344 // We need to add this separately from the scale above to help with
4345 // SDAG consecutive load/store merging.
4346 if (ResultPtr->getType() != I8PtrTy)
4347 ResultPtr = Builder.CreatePointerCast(ResultPtr, I8PtrTy);
4348 ResultPtr = Builder.CreateGEP(I8Ty, ResultPtr, ResultIndex, "sunkaddr");
4349 }
4350
4351 ResultIndex = V;
4352 }
4353
4354 if (!ResultIndex) {
4355 SunkAddr = ResultPtr;
4356 } else {
4357 if (ResultPtr->getType() != I8PtrTy)
4358 ResultPtr = Builder.CreatePointerCast(ResultPtr, I8PtrTy);
4359 SunkAddr = Builder.CreateGEP(I8Ty, ResultPtr, ResultIndex, "sunkaddr");
4360 }
4361
4362 if (SunkAddr->getType() != Addr->getType())
4363 SunkAddr = Builder.CreatePointerCast(SunkAddr, Addr->getType());
4364 }
4365 } else {
4366 DEBUG(dbgs() << "CGP: SINKING nonlocal addrmode: " << AddrMode << " for "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: SINKING nonlocal addrmode: "
<< AddrMode << " for " << *MemoryInst <<
"\n"; } } while (false)
4367 << *MemoryInst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: SINKING nonlocal addrmode: "
<< AddrMode << " for " << *MemoryInst <<
"\n"; } } while (false)
;
4368 Type *IntPtrTy = DL->getIntPtrType(Addr->getType());
4369 Value *Result = nullptr;
4370
4371 // Start with the base register. Do this first so that subsequent address
4372 // matching finds it last, which will prevent it from trying to match it
4373 // as the scaled value in case it happens to be a mul. That would be
4374 // problematic if we've sunk a different mul for the scale, because then
4375 // we'd end up sinking both muls.
4376 if (AddrMode.BaseReg) {
4377 Value *V = AddrMode.BaseReg;
4378 if (V->getType()->isPointerTy())
4379 V = Builder.CreatePtrToInt(V, IntPtrTy, "sunkaddr");
4380 if (V->getType() != IntPtrTy)
4381 V = Builder.CreateIntCast(V, IntPtrTy, /*isSigned=*/true, "sunkaddr");
4382 Result = V;
4383 }
4384
4385 // Add the scale value.
4386 if (AddrMode.Scale) {
4387 Value *V = AddrMode.ScaledReg;
4388 if (V->getType() == IntPtrTy) {
4389 // done.
4390 } else if (V->getType()->isPointerTy()) {
4391 V = Builder.CreatePtrToInt(V, IntPtrTy, "sunkaddr");
4392 } else if (cast<IntegerType>(IntPtrTy)->getBitWidth() <
4393 cast<IntegerType>(V->getType())->getBitWidth()) {
4394 V = Builder.CreateTrunc(V, IntPtrTy, "sunkaddr");
4395 } else {
4396 // It is only safe to sign extend the BaseReg if we know that the math
4397 // required to create it did not overflow before we extend it. Since
4398 // the original IR value was tossed in favor of a constant back when
4399 // the AddrMode was created we need to bail out gracefully if widths
4400 // do not match instead of extending it.
4401 Instruction *I = dyn_cast_or_null<Instruction>(Result);
4402 if (I && (Result != AddrMode.BaseReg))
4403 I->eraseFromParent();
4404 return false;
4405 }
4406 if (AddrMode.Scale != 1)
4407 V = Builder.CreateMul(V, ConstantInt::get(IntPtrTy, AddrMode.Scale),
4408 "sunkaddr");
4409 if (Result)
4410 Result = Builder.CreateAdd(Result, V, "sunkaddr");
4411 else
4412 Result = V;
4413 }
4414
4415 // Add in the BaseGV if present.
4416 if (AddrMode.BaseGV) {
4417 Value *V = Builder.CreatePtrToInt(AddrMode.BaseGV, IntPtrTy, "sunkaddr");
4418 if (Result)
4419 Result = Builder.CreateAdd(Result, V, "sunkaddr");
4420 else
4421 Result = V;
4422 }
4423
4424 // Add in the Base Offset if present.
4425 if (AddrMode.BaseOffs) {
4426 Value *V = ConstantInt::get(IntPtrTy, AddrMode.BaseOffs);
4427 if (Result)
4428 Result = Builder.CreateAdd(Result, V, "sunkaddr");
4429 else
4430 Result = V;
4431 }
4432
4433 if (!Result)
4434 SunkAddr = Constant::getNullValue(Addr->getType());
4435 else
4436 SunkAddr = Builder.CreateIntToPtr(Result, Addr->getType(), "sunkaddr");
4437 }
4438
4439 MemoryInst->replaceUsesOfWith(Repl, SunkAddr);
4440
4441 // If we have no uses, recursively delete the value and all dead instructions
4442 // using it.
4443 if (Repl->use_empty()) {
4444 // This can cause recursive deletion, which can invalidate our iterator.
4445 // Use a WeakVH to hold onto it in case this happens.
4446 Value *CurValue = &*CurInstIterator;
4447 WeakVH IterHandle(CurValue);
4448 BasicBlock *BB = CurInstIterator->getParent();
4449
4450 RecursivelyDeleteTriviallyDeadInstructions(Repl, TLInfo);
4451
4452 if (IterHandle != CurValue) {
4453 // If the iterator instruction was recursively deleted, start over at the
4454 // start of the block.
4455 CurInstIterator = BB->begin();
4456 SunkAddrs.clear();
4457 }
4458 }
4459 ++NumMemoryInsts;
4460 return true;
4461}
4462
4463/// If there are any memory operands, use OptimizeMemoryInst to sink their
4464/// address computing into the block when possible / profitable.
4465bool CodeGenPrepare::optimizeInlineAsmInst(CallInst *CS) {
4466 bool MadeChange = false;
4467
4468 const TargetRegisterInfo *TRI =
4469 TM->getSubtargetImpl(*CS->getParent()->getParent())->getRegisterInfo();
4470 TargetLowering::AsmOperandInfoVector TargetConstraints =
4471 TLI->ParseConstraints(*DL, TRI, CS);
4472 unsigned ArgNo = 0;
4473 for (unsigned i = 0, e = TargetConstraints.size(); i != e; ++i) {
4474 TargetLowering::AsmOperandInfo &OpInfo = TargetConstraints[i];
4475
4476 // Compute the constraint code and ConstraintType to use.
4477 TLI->ComputeConstraintToUse(OpInfo, SDValue());
4478
4479 if (OpInfo.ConstraintType == TargetLowering::C_Memory &&
4480 OpInfo.isIndirect) {
4481 Value *OpVal = CS->getArgOperand(ArgNo++);
4482 MadeChange |= optimizeMemoryInst(CS, OpVal, OpVal->getType(), ~0u);
4483 } else if (OpInfo.Type == InlineAsm::isInput)
4484 ArgNo++;
4485 }
4486
4487 return MadeChange;
4488}
4489
4490/// \brief Check if all the uses of \p Val are equivalent (or free) zero or
4491/// sign extensions.
4492static bool hasSameExtUse(Value *Val, const TargetLowering &TLI) {
4493 assert(!Val->use_empty() && "Input must have at least one use")((!Val->use_empty() && "Input must have at least one use"
) ? static_cast<void> (0) : __assert_fail ("!Val->use_empty() && \"Input must have at least one use\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 4493, __PRETTY_FUNCTION__))
;
4494 const Instruction *FirstUser = cast<Instruction>(*Val->user_begin());
4495 bool IsSExt = isa<SExtInst>(FirstUser);
4496 Type *ExtTy = FirstUser->getType();
4497 for (const User *U : Val->users()) {
4498 const Instruction *UI = cast<Instruction>(U);
4499 if ((IsSExt && !isa<SExtInst>(UI)) || (!IsSExt && !isa<ZExtInst>(UI)))
4500 return false;
4501 Type *CurTy = UI->getType();
4502 // Same input and output types: Same instruction after CSE.
4503 if (CurTy == ExtTy)
4504 continue;
4505
4506 // If IsSExt is true, we are in this situation:
4507 // a = Val
4508 // b = sext ty1 a to ty2
4509 // c = sext ty1 a to ty3
4510 // Assuming ty2 is shorter than ty3, this could be turned into:
4511 // a = Val
4512 // b = sext ty1 a to ty2
4513 // c = sext ty2 b to ty3
4514 // However, the last sext is not free.
4515 if (IsSExt)
4516 return false;
4517
4518 // This is a ZExt, maybe this is free to extend from one type to another.
4519 // In that case, we would not account for a different use.
4520 Type *NarrowTy;
4521 Type *LargeTy;
4522 if (ExtTy->getScalarType()->getIntegerBitWidth() >
4523 CurTy->getScalarType()->getIntegerBitWidth()) {
4524 NarrowTy = CurTy;
4525 LargeTy = ExtTy;
4526 } else {
4527 NarrowTy = ExtTy;
4528 LargeTy = CurTy;
4529 }
4530
4531 if (!TLI.isZExtFree(NarrowTy, LargeTy))
4532 return false;
4533 }
4534 // All uses are the same or can be derived from one another for free.
4535 return true;
4536}
4537
4538/// \brief Try to speculatively promote extensions in \p Exts and continue
4539/// promoting through newly promoted operands recursively as far as doing so is
4540/// profitable. Save extensions profitably moved up, in \p ProfitablyMovedExts.
4541/// When some promotion happened, \p TPT contains the proper state to revert
4542/// them.
4543///
4544/// \return true if some promotion happened, false otherwise.
4545bool CodeGenPrepare::tryToPromoteExts(
4546 TypePromotionTransaction &TPT, const SmallVectorImpl<Instruction *> &Exts,
4547 SmallVectorImpl<Instruction *> &ProfitablyMovedExts,
4548 unsigned CreatedInstsCost) {
4549 bool Promoted = false;
4550
4551 // Iterate over all the extensions to try to promote them.
4552 for (auto I : Exts) {
4553 // Early check if we directly have ext(load).
4554 if (isa<LoadInst>(I->getOperand(0))) {
4555 ProfitablyMovedExts.push_back(I);
4556 continue;
4557 }
4558
4559 // Check whether or not we want to do any promotion. The reason we have
4560 // this check inside the for loop is to catch the case where an extension
4561 // is directly fed by a load because in such case the extension can be moved
4562 // up without any promotion on its operands.
4563 if (!TLI || !TLI->enableExtLdPromotion() || DisableExtLdPromotion)
4564 return false;
4565
4566 // Get the action to perform the promotion.
4567 TypePromotionHelper::Action TPH =
4568 TypePromotionHelper::getAction(I, InsertedInsts, *TLI, PromotedInsts);
4569 // Check if we can promote.
4570 if (!TPH) {
4571 // Save the current extension as we cannot move up through its operand.
4572 ProfitablyMovedExts.push_back(I);
4573 continue;
4574 }
4575
4576 // Save the current state.
4577 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
4578 TPT.getRestorationPoint();
4579 SmallVector<Instruction *, 4> NewExts;
4580 unsigned NewCreatedInstsCost = 0;
4581 unsigned ExtCost = !TLI->isExtFree(I);
4582 // Promote.
4583 Value *PromotedVal = TPH(I, TPT, PromotedInsts, NewCreatedInstsCost,
4584 &NewExts, nullptr, *TLI);
4585 assert(PromotedVal &&((PromotedVal && "TypePromotionHelper should have filtered out those cases"
) ? static_cast<void> (0) : __assert_fail ("PromotedVal && \"TypePromotionHelper should have filtered out those cases\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 4586, __PRETTY_FUNCTION__))
4586 "TypePromotionHelper should have filtered out those cases")((PromotedVal && "TypePromotionHelper should have filtered out those cases"
) ? static_cast<void> (0) : __assert_fail ("PromotedVal && \"TypePromotionHelper should have filtered out those cases\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 4586, __PRETTY_FUNCTION__))
;
4587
4588 // We would be able to merge only one extension in a load.
4589 // Therefore, if we have more than 1 new extension we heuristically
4590 // cut this search path, because it means we degrade the code quality.
4591 // With exactly 2, the transformation is neutral, because we will merge
4592 // one extension but leave one. However, we optimistically keep going,
4593 // because the new extension may be removed too.
4594 long long TotalCreatedInstsCost = CreatedInstsCost + NewCreatedInstsCost;
4595 // FIXME: It would be possible to propagate a negative value instead of
4596 // conservatively ceiling it to 0.
4597 TotalCreatedInstsCost =
4598 std::max((long long)0, (TotalCreatedInstsCost - ExtCost));
4599 if (!StressExtLdPromotion &&
4600 (TotalCreatedInstsCost > 1 ||
4601 !isPromotedInstructionLegal(*TLI, *DL, PromotedVal))) {
4602 // This promotion is not profitable, rollback to the previous state, and
4603 // save the current extension in ProfitablyMovedExts as the latest
4604 // speculative promotion turned out to be unprofitable.
4605 TPT.rollback(LastKnownGood);
4606 ProfitablyMovedExts.push_back(I);
4607 continue;
4608 }
4609 // Continue promoting NewExts as far as doing so is profitable.
4610 SmallVector<Instruction *, 2> NewlyMovedExts;
4611 (void)tryToPromoteExts(TPT, NewExts, NewlyMovedExts, TotalCreatedInstsCost);
4612 bool NewPromoted = false;
4613 for (auto ExtInst : NewlyMovedExts) {
4614 Instruction *MovedExt = cast<Instruction>(ExtInst);
4615 Value *ExtOperand = MovedExt->getOperand(0);
4616 // If we have reached to a load, we need this extra profitability check
4617 // as it could potentially be merged into an ext(load).
4618 if (isa<LoadInst>(ExtOperand) &&
4619 !(StressExtLdPromotion || NewCreatedInstsCost <= ExtCost ||
4620 (ExtOperand->hasOneUse() || hasSameExtUse(ExtOperand, *TLI))))
4621 continue;
4622
4623 ProfitablyMovedExts.push_back(MovedExt);
4624 NewPromoted = true;
4625 }
4626
4627 // If none of speculative promotions for NewExts is profitable, rollback
4628 // and save the current extension (I) as the last profitable extension.
4629 if (!NewPromoted) {
4630 TPT.rollback(LastKnownGood);
4631 ProfitablyMovedExts.push_back(I);
4632 continue;
4633 }
4634 // The promotion is profitable.
4635 Promoted = true;
4636 }
4637 return Promoted;
4638}
4639
4640/// Merging redundant sexts when one is dominating the other.
4641bool CodeGenPrepare::mergeSExts(Function &F) {
4642 DominatorTree DT(F);
4643 bool Changed = false;
4644 for (auto &Entry : ValToSExtendedUses) {
4645 SExts &Insts = Entry.second;
4646 SExts CurPts;
4647 for (Instruction *Inst : Insts) {
4648 if (RemovedInsts.count(Inst) || !isa<SExtInst>(Inst) ||
4649 Inst->getOperand(0) != Entry.first)
4650 continue;
4651 bool inserted = false;
4652 for (auto &Pt : CurPts) {
4653 if (DT.dominates(Inst, Pt)) {
4654 Pt->replaceAllUsesWith(Inst);
4655 RemovedInsts.insert(Pt);
4656 Pt->removeFromParent();
4657 Pt = Inst;
4658 inserted = true;
4659 Changed = true;
4660 break;
4661 }
4662 if (!DT.dominates(Pt, Inst))
4663 // Give up if we need to merge in a common dominator as the
4664 // expermients show it is not profitable.
4665 continue;
4666 Inst->replaceAllUsesWith(Pt);
4667 RemovedInsts.insert(Inst);
4668 Inst->removeFromParent();
4669 inserted = true;
4670 Changed = true;
4671 break;
4672 }
4673 if (!inserted)
4674 CurPts.push_back(Inst);
4675 }
4676 }
4677 return Changed;
4678}
4679
4680/// Return true, if an ext(load) can be formed from an extension in
4681/// \p MovedExts.
4682bool CodeGenPrepare::canFormExtLd(
4683 const SmallVectorImpl<Instruction *> &MovedExts, LoadInst *&LI,
4684 Instruction *&Inst, bool HasPromoted) {
4685 for (auto *MovedExtInst : MovedExts) {
4686 if (isa<LoadInst>(MovedExtInst->getOperand(0))) {
4687 LI = cast<LoadInst>(MovedExtInst->getOperand(0));
4688 Inst = MovedExtInst;
4689 break;
4690 }
4691 }
4692 if (!LI)
4693 return false;
4694
4695 // If they're already in the same block, there's nothing to do.
4696 // Make the cheap checks first if we did not promote.
4697 // If we promoted, we need to check if it is indeed profitable.
4698 if (!HasPromoted && LI->getParent() == Inst->getParent())
4699 return false;
4700
4701 EVT VT = TLI->getValueType(*DL, Inst->getType());
4702 EVT LoadVT = TLI->getValueType(*DL, LI->getType());
4703
4704 // If the load has other users and the truncate is not free, this probably
4705 // isn't worthwhile.
4706 if (!LI->hasOneUse() && (TLI->isTypeLegal(LoadVT) || !TLI->isTypeLegal(VT)) &&
4707 !TLI->isTruncateFree(Inst->getType(), LI->getType()))
4708 return false;
4709
4710 // Check whether the target supports casts folded into loads.
4711 unsigned LType;
4712 if (isa<ZExtInst>(Inst))
4713 LType = ISD::ZEXTLOAD;
4714 else {
4715 assert(isa<SExtInst>(Inst) && "Unexpected ext type!")((isa<SExtInst>(Inst) && "Unexpected ext type!"
) ? static_cast<void> (0) : __assert_fail ("isa<SExtInst>(Inst) && \"Unexpected ext type!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 4715, __PRETTY_FUNCTION__))
;
4716 LType = ISD::SEXTLOAD;
4717 }
4718
4719 return TLI->isLoadExtLegal(LType, VT, LoadVT);
4720}
4721
4722/// Move a zext or sext fed by a load into the same basic block as the load,
4723/// unless conditions are unfavorable. This allows SelectionDAG to fold the
4724/// extend into the load.
4725///
4726/// E.g.,
4727/// \code
4728/// %ld = load i32* %addr
4729/// %add = add nuw i32 %ld, 4
4730/// %zext = zext i32 %add to i64
4731// \endcode
4732/// =>
4733/// \code
4734/// %ld = load i32* %addr
4735/// %zext = zext i32 %ld to i64
4736/// %add = add nuw i64 %zext, 4
4737/// \encode
4738/// Note that the promotion in %add to i64 is done in tryToPromoteExts(), which
4739/// allow us to match zext(load i32*) to i64.
4740///
4741/// Also, try to promote the computations used to obtain a sign extended
4742/// value used into memory accesses.
4743/// E.g.,
4744/// \code
4745/// a = add nsw i32 b, 3
4746/// d = sext i32 a to i64
4747/// e = getelementptr ..., i64 d
4748/// \endcode
4749/// =>
4750/// \code
4751/// f = sext i32 b to i64
4752/// a = add nsw i64 f, 3
4753/// e = getelementptr ..., i64 a
4754/// \endcode
4755///
4756/// \p Inst[in/out] the extension may be modified during the process if some
4757/// promotions apply.
4758bool CodeGenPrepare::optimizeExt(Instruction *&Inst) {
4759 // ExtLoad formation and address type promotion infrastructure requires TLI to
4760 // be effective.
4761 if (!TLI)
4762 return false;
4763
4764 bool AllowPromotionWithoutCommonHeader = false;
4765 /// See if it is an interesting sext operations for the address type
4766 /// promotion before trying to promote it, e.g., the ones with the right
4767 /// type and used in memory accesses.
4768 bool ATPConsiderable = TTI->shouldConsiderAddressTypePromotion(
4769 *Inst, AllowPromotionWithoutCommonHeader);
4770 TypePromotionTransaction TPT(RemovedInsts);
4771 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
4772 TPT.getRestorationPoint();
4773 SmallVector<Instruction *, 1> Exts;
4774 SmallVector<Instruction *, 2> SpeculativelyMovedExts;
4775 Exts.push_back(Inst);
4776
4777 bool HasPromoted = tryToPromoteExts(TPT, Exts, SpeculativelyMovedExts);
4778
4779 // Look for a load being extended.
4780 LoadInst *LI = nullptr;
4781 Instruction *ExtFedByLoad;
4782
4783 // Try to promote a chain of computation if it allows to form an extended
4784 // load.
4785 if (canFormExtLd(SpeculativelyMovedExts, LI, ExtFedByLoad, HasPromoted)) {
4786 assert(LI && ExtFedByLoad && "Expect a valid load and extension")((LI && ExtFedByLoad && "Expect a valid load and extension"
) ? static_cast<void> (0) : __assert_fail ("LI && ExtFedByLoad && \"Expect a valid load and extension\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 4786, __PRETTY_FUNCTION__))
;
4787 TPT.commit();
4788 // Move the extend into the same block as the load
4789 ExtFedByLoad->removeFromParent();
4790 ExtFedByLoad->insertAfter(LI);
4791 // CGP does not check if the zext would be speculatively executed when moved
4792 // to the same basic block as the load. Preserving its original location
4793 // would pessimize the debugging experience, as well as negatively impact
4794 // the quality of sample pgo. We don't want to use "line 0" as that has a
4795 // size cost in the line-table section and logically the zext can be seen as
4796 // part of the load. Therefore we conservatively reuse the same debug
4797 // location for the load and the zext.
4798 ExtFedByLoad->setDebugLoc(LI->getDebugLoc());
4799 ++NumExtsMoved;
4800 Inst = ExtFedByLoad;
4801 return true;
4802 }
4803
4804 // Continue promoting SExts if known as considerable depending on targets.
4805 if (ATPConsiderable &&
4806 performAddressTypePromotion(Inst, AllowPromotionWithoutCommonHeader,
4807 HasPromoted, TPT, SpeculativelyMovedExts))
4808 return true;
4809
4810 TPT.rollback(LastKnownGood);
4811 return false;
4812}
4813
4814// Perform address type promotion if doing so is profitable.
4815// If AllowPromotionWithoutCommonHeader == false, we should find other sext
4816// instructions that sign extended the same initial value. However, if
4817// AllowPromotionWithoutCommonHeader == true, we expect promoting the
4818// extension is just profitable.
4819bool CodeGenPrepare::performAddressTypePromotion(
4820 Instruction *&Inst, bool AllowPromotionWithoutCommonHeader,
4821 bool HasPromoted, TypePromotionTransaction &TPT,
4822 SmallVectorImpl<Instruction *> &SpeculativelyMovedExts) {
4823 bool Promoted = false;
4824 SmallPtrSet<Instruction *, 1> UnhandledExts;
4825 bool AllSeenFirst = true;
4826 for (auto I : SpeculativelyMovedExts) {
4827 Value *HeadOfChain = I->getOperand(0);
4828 DenseMap<Value *, Instruction *>::iterator AlreadySeen =
4829 SeenChainsForSExt.find(HeadOfChain);
4830 // If there is an unhandled SExt which has the same header, try to promote
4831 // it as well.
4832 if (AlreadySeen != SeenChainsForSExt.end()) {
4833 if (AlreadySeen->second != nullptr)
4834 UnhandledExts.insert(AlreadySeen->second);
4835 AllSeenFirst = false;
4836 }
4837 }
4838
4839 if (!AllSeenFirst || (AllowPromotionWithoutCommonHeader &&
4840 SpeculativelyMovedExts.size() == 1)) {
4841 TPT.commit();
4842 if (HasPromoted)
4843 Promoted = true;
4844 for (auto I : SpeculativelyMovedExts) {
4845 Value *HeadOfChain = I->getOperand(0);
4846 SeenChainsForSExt[HeadOfChain] = nullptr;
4847 ValToSExtendedUses[HeadOfChain].push_back(I);
4848 }
4849 // Update Inst as promotion happen.
4850 Inst = SpeculativelyMovedExts.pop_back_val();
4851 } else {
4852 // This is the first chain visited from the header, keep the current chain
4853 // as unhandled. Defer to promote this until we encounter another SExt
4854 // chain derived from the same header.
4855 for (auto I : SpeculativelyMovedExts) {
4856 Value *HeadOfChain = I->getOperand(0);
4857 SeenChainsForSExt[HeadOfChain] = Inst;
4858 }
4859 return false;
4860 }
4861
4862 if (!AllSeenFirst && !UnhandledExts.empty())
4863 for (auto VisitedSExt : UnhandledExts) {
4864 if (RemovedInsts.count(VisitedSExt))
4865 continue;
4866 TypePromotionTransaction TPT(RemovedInsts);
4867 SmallVector<Instruction *, 1> Exts;
4868 SmallVector<Instruction *, 2> Chains;
4869 Exts.push_back(VisitedSExt);
4870 bool HasPromoted = tryToPromoteExts(TPT, Exts, Chains);
4871 TPT.commit();
4872 if (HasPromoted)
4873 Promoted = true;
4874 for (auto I : Chains) {
4875 Value *HeadOfChain = I->getOperand(0);
4876 // Mark this as handled.
4877 SeenChainsForSExt[HeadOfChain] = nullptr;
4878 ValToSExtendedUses[HeadOfChain].push_back(I);
4879 }
4880 }
4881 return Promoted;
4882}
4883
4884bool CodeGenPrepare::optimizeExtUses(Instruction *I) {
4885 BasicBlock *DefBB = I->getParent();
4886
4887 // If the result of a {s|z}ext and its source are both live out, rewrite all
4888 // other uses of the source with result of extension.
4889 Value *Src = I->getOperand(0);
4890 if (Src->hasOneUse())
4891 return false;
4892
4893 // Only do this xform if truncating is free.
4894 if (TLI && !TLI->isTruncateFree(I->getType(), Src->getType()))
4895 return false;
4896
4897 // Only safe to perform the optimization if the source is also defined in
4898 // this block.
4899 if (!isa<Instruction>(Src) || DefBB != cast<Instruction>(Src)->getParent())
4900 return false;
4901
4902 bool DefIsLiveOut = false;
4903 for (User *U : I->users()) {
4904 Instruction *UI = cast<Instruction>(U);
4905
4906 // Figure out which BB this ext is used in.
4907 BasicBlock *UserBB = UI->getParent();
4908 if (UserBB == DefBB) continue;
4909 DefIsLiveOut = true;
4910 break;
4911 }
4912 if (!DefIsLiveOut)
4913 return false;
4914
4915 // Make sure none of the uses are PHI nodes.
4916 for (User *U : Src->users()) {
4917 Instruction *UI = cast<Instruction>(U);
4918 BasicBlock *UserBB = UI->getParent();
4919 if (UserBB == DefBB) continue;
4920 // Be conservative. We don't want this xform to end up introducing
4921 // reloads just before load / store instructions.
4922 if (isa<PHINode>(UI) || isa<LoadInst>(UI) || isa<StoreInst>(UI))
4923 return false;
4924 }
4925
4926 // InsertedTruncs - Only insert one trunc in each block once.
4927 DenseMap<BasicBlock*, Instruction*> InsertedTruncs;
4928
4929 bool MadeChange = false;
4930 for (Use &U : Src->uses()) {
4931 Instruction *User = cast<Instruction>(U.getUser());
4932
4933 // Figure out which BB this ext is used in.
4934 BasicBlock *UserBB = User->getParent();
4935 if (UserBB == DefBB) continue;
4936
4937 // Both src and def are live in this block. Rewrite the use.
4938 Instruction *&InsertedTrunc = InsertedTruncs[UserBB];
4939
4940 if (!InsertedTrunc) {
4941 BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
4942 assert(InsertPt != UserBB->end())((InsertPt != UserBB->end()) ? static_cast<void> (0)
: __assert_fail ("InsertPt != UserBB->end()", "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 4942, __PRETTY_FUNCTION__))
;
4943 InsertedTrunc = new TruncInst(I, Src->getType(), "", &*InsertPt);
4944 InsertedInsts.insert(InsertedTrunc);
4945 }
4946
4947 // Replace a use of the {s|z}ext source with a use of the result.
4948 U = InsertedTrunc;
4949 ++NumExtUses;
4950 MadeChange = true;
4951 }
4952
4953 return MadeChange;
4954}
4955
4956// Find loads whose uses only use some of the loaded value's bits. Add an "and"
4957// just after the load if the target can fold this into one extload instruction,
4958// with the hope of eliminating some of the other later "and" instructions using
4959// the loaded value. "and"s that are made trivially redundant by the insertion
4960// of the new "and" are removed by this function, while others (e.g. those whose
4961// path from the load goes through a phi) are left for isel to potentially
4962// remove.
4963//
4964// For example:
4965//
4966// b0:
4967// x = load i32
4968// ...
4969// b1:
4970// y = and x, 0xff
4971// z = use y
4972//
4973// becomes:
4974//
4975// b0:
4976// x = load i32
4977// x' = and x, 0xff
4978// ...
4979// b1:
4980// z = use x'
4981//
4982// whereas:
4983//
4984// b0:
4985// x1 = load i32
4986// ...
4987// b1:
4988// x2 = load i32
4989// ...
4990// b2:
4991// x = phi x1, x2
4992// y = and x, 0xff
4993//
4994// becomes (after a call to optimizeLoadExt for each load):
4995//
4996// b0:
4997// x1 = load i32
4998// x1' = and x1, 0xff
4999// ...
5000// b1:
5001// x2 = load i32
5002// x2' = and x2, 0xff
5003// ...
5004// b2:
5005// x = phi x1', x2'
5006// y = and x, 0xff
5007//
5008
5009bool CodeGenPrepare::optimizeLoadExt(LoadInst *Load) {
5010
5011 if (!Load->isSimple() ||
5012 !(Load->getType()->isIntegerTy() || Load->getType()->isPointerTy()))
5013 return false;
5014
5015 // Skip loads we've already transformed.
5016 if (Load->hasOneUse() &&
5017 InsertedInsts.count(cast<Instruction>(*Load->user_begin())))
5018 return false;
5019
5020 // Look at all uses of Load, looking through phis, to determine how many bits
5021 // of the loaded value are needed.
5022 SmallVector<Instruction *, 8> WorkList;
5023 SmallPtrSet<Instruction *, 16> Visited;
5024 SmallVector<Instruction *, 8> AndsToMaybeRemove;
5025 for (auto *U : Load->users())
5026 WorkList.push_back(cast<Instruction>(U));
5027
5028 EVT LoadResultVT = TLI->getValueType(*DL, Load->getType());
5029 unsigned BitWidth = LoadResultVT.getSizeInBits();
5030 APInt DemandBits(BitWidth, 0);
5031 APInt WidestAndBits(BitWidth, 0);
5032
5033 while (!WorkList.empty()) {
5034 Instruction *I = WorkList.back();
5035 WorkList.pop_back();
5036
5037 // Break use-def graph loops.
5038 if (!Visited.insert(I).second)
5039 continue;
5040
5041 // For a PHI node, push all of its users.
5042 if (auto *Phi = dyn_cast<PHINode>(I)) {
5043 for (auto *U : Phi->users())
5044 WorkList.push_back(cast<Instruction>(U));
5045 continue;
5046 }
5047
5048 switch (I->getOpcode()) {
5049 case llvm::Instruction::And: {
5050 auto *AndC = dyn_cast<ConstantInt>(I->getOperand(1));
5051 if (!AndC)
5052 return false;
5053 APInt AndBits = AndC->getValue();
5054 DemandBits |= AndBits;
5055 // Keep track of the widest and mask we see.
5056 if (AndBits.ugt(WidestAndBits))
5057 WidestAndBits = AndBits;
5058 if (AndBits == WidestAndBits && I->getOperand(0) == Load)
5059 AndsToMaybeRemove.push_back(I);
5060 break;
5061 }
5062
5063 case llvm::Instruction::Shl: {
5064 auto *ShlC = dyn_cast<ConstantInt>(I->getOperand(1));
5065 if (!ShlC)
5066 return false;
5067 uint64_t ShiftAmt = ShlC->getLimitedValue(BitWidth - 1);
5068 DemandBits.setLowBits(BitWidth - ShiftAmt);
5069 break;
5070 }
5071
5072 case llvm::Instruction::Trunc: {
5073 EVT TruncVT = TLI->getValueType(*DL, I->getType());
5074 unsigned TruncBitWidth = TruncVT.getSizeInBits();
5075 DemandBits.setLowBits(TruncBitWidth);
5076 break;
5077 }
5078
5079 default:
5080 return false;
5081 }
5082 }
5083
5084 uint32_t ActiveBits = DemandBits.getActiveBits();
5085 // Avoid hoisting (and (load x) 1) since it is unlikely to be folded by the
5086 // target even if isLoadExtLegal says an i1 EXTLOAD is valid. For example,
5087 // for the AArch64 target isLoadExtLegal(ZEXTLOAD, i32, i1) returns true, but
5088 // (and (load x) 1) is not matched as a single instruction, rather as a LDR
5089 // followed by an AND.
5090 // TODO: Look into removing this restriction by fixing backends to either
5091 // return false for isLoadExtLegal for i1 or have them select this pattern to
5092 // a single instruction.
5093 //
5094 // Also avoid hoisting if we didn't see any ands with the exact DemandBits
5095 // mask, since these are the only ands that will be removed by isel.
5096 if (ActiveBits <= 1 || !DemandBits.isMask(ActiveBits) ||
5097 WidestAndBits != DemandBits)
5098 return false;
5099
5100 LLVMContext &Ctx = Load->getType()->getContext();
5101 Type *TruncTy = Type::getIntNTy(Ctx, ActiveBits);
5102 EVT TruncVT = TLI->getValueType(*DL, TruncTy);
5103
5104 // Reject cases that won't be matched as extloads.
5105 if (!LoadResultVT.bitsGT(TruncVT) || !TruncVT.isRound() ||
5106 !TLI->isLoadExtLegal(ISD::ZEXTLOAD, LoadResultVT, TruncVT))
5107 return false;
5108
5109 IRBuilder<> Builder(Load->getNextNode());
5110 auto *NewAnd = dyn_cast<Instruction>(
5111 Builder.CreateAnd(Load, ConstantInt::get(Ctx, DemandBits)));
5112 // Mark this instruction as "inserted by CGP", so that other
5113 // optimizations don't touch it.
5114 InsertedInsts.insert(NewAnd);
5115
5116 // Replace all uses of load with new and (except for the use of load in the
5117 // new and itself).
5118 Load->replaceAllUsesWith(NewAnd);
5119 NewAnd->setOperand(0, Load);
5120
5121 // Remove any and instructions that are now redundant.
5122 for (auto *And : AndsToMaybeRemove)
5123 // Check that the and mask is the same as the one we decided to put on the
5124 // new and.
5125 if (cast<ConstantInt>(And->getOperand(1))->getValue() == DemandBits) {
5126 And->replaceAllUsesWith(NewAnd);
5127 if (&*CurInstIterator == And)
5128 CurInstIterator = std::next(And->getIterator());
5129 And->eraseFromParent();
5130 ++NumAndUses;
5131 }
5132
5133 ++NumAndsAdded;
5134 return true;
5135}
5136
5137/// Check if V (an operand of a select instruction) is an expensive instruction
5138/// that is only used once.
5139static bool sinkSelectOperand(const TargetTransformInfo *TTI, Value *V) {
5140 auto *I = dyn_cast<Instruction>(V);
5141 // If it's safe to speculatively execute, then it should not have side
5142 // effects; therefore, it's safe to sink and possibly *not* execute.
5143 return I && I->hasOneUse() && isSafeToSpeculativelyExecute(I) &&
5144 TTI->getUserCost(I) >= TargetTransformInfo::TCC_Expensive;
5145}
5146
5147/// Returns true if a SelectInst should be turned into an explicit branch.
5148static bool isFormingBranchFromSelectProfitable(const TargetTransformInfo *TTI,
5149 const TargetLowering *TLI,
5150 SelectInst *SI) {
5151 // If even a predictable select is cheap, then a branch can't be cheaper.
5152 if (!TLI->isPredictableSelectExpensive())
5153 return false;
5154
5155 // FIXME: This should use the same heuristics as IfConversion to determine
5156 // whether a select is better represented as a branch.
5157
5158 // If metadata tells us that the select condition is obviously predictable,
5159 // then we want to replace the select with a branch.
5160 uint64_t TrueWeight, FalseWeight;
5161 if (SI->extractProfMetadata(TrueWeight, FalseWeight)) {
5162 uint64_t Max = std::max(TrueWeight, FalseWeight);
5163 uint64_t Sum = TrueWeight + FalseWeight;
5164 if (Sum != 0) {
5165 auto Probability = BranchProbability::getBranchProbability(Max, Sum);
5166 if (Probability > TLI->getPredictableBranchThreshold())
5167 return true;
5168 }
5169 }
5170
5171 CmpInst *Cmp = dyn_cast<CmpInst>(SI->getCondition());
5172
5173 // If a branch is predictable, an out-of-order CPU can avoid blocking on its
5174 // comparison condition. If the compare has more than one use, there's
5175 // probably another cmov or setcc around, so it's not worth emitting a branch.
5176 if (!Cmp || !Cmp->hasOneUse())
5177 return false;
5178
5179 // If either operand of the select is expensive and only needed on one side
5180 // of the select, we should form a branch.
5181 if (sinkSelectOperand(TTI, SI->getTrueValue()) ||
5182 sinkSelectOperand(TTI, SI->getFalseValue()))
5183 return true;
5184
5185 return false;
5186}
5187
5188/// If \p isTrue is true, return the true value of \p SI, otherwise return
5189/// false value of \p SI. If the true/false value of \p SI is defined by any
5190/// select instructions in \p Selects, look through the defining select
5191/// instruction until the true/false value is not defined in \p Selects.
5192static Value *getTrueOrFalseValue(
5193 SelectInst *SI, bool isTrue,
5194 const SmallPtrSet<const Instruction *, 2> &Selects) {
5195 Value *V;
15
'V' declared without an initial value
5196
5197 for (SelectInst *DefSI = SI; DefSI != nullptr && Selects.count(DefSI);
16
Loop condition is false. Execution continues on line 5203
5198 DefSI = dyn_cast<SelectInst>(V)) {
5199 assert(DefSI->getCondition() == SI->getCondition() &&((DefSI->getCondition() == SI->getCondition() &&
"The condition of DefSI does not match with SI") ? static_cast
<void> (0) : __assert_fail ("DefSI->getCondition() == SI->getCondition() && \"The condition of DefSI does not match with SI\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 5200, __PRETTY_FUNCTION__))
5200 "The condition of DefSI does not match with SI")((DefSI->getCondition() == SI->getCondition() &&
"The condition of DefSI does not match with SI") ? static_cast
<void> (0) : __assert_fail ("DefSI->getCondition() == SI->getCondition() && \"The condition of DefSI does not match with SI\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 5200, __PRETTY_FUNCTION__))
;
5201 V = (isTrue ? DefSI->getTrueValue() : DefSI->getFalseValue());
5202 }
5203 return V;
17
Undefined or garbage value returned to caller
5204}
5205
5206/// If we have a SelectInst that will likely profit from branch prediction,
5207/// turn it into a branch.
5208bool CodeGenPrepare::optimizeSelectInst(SelectInst *SI) {
5209 // Find all consecutive select instructions that share the same condition.
5210 SmallVector<SelectInst *, 2> ASI;
5211 ASI.push_back(SI);
5212 for (BasicBlock::iterator It = ++BasicBlock::iterator(SI);
1
Loop condition is false. Execution continues on line 5222
5213 It != SI->getParent()->end(); ++It) {
5214 SelectInst *I = dyn_cast<SelectInst>(&*It);
5215 if (I && SI->getCondition() == I->getCondition()) {
5216 ASI.push_back(I);
5217 } else {
5218 break;
5219 }
5220 }
5221
5222 SelectInst *LastSI = ASI.back();
5223 // Increment the current iterator to skip all the rest of select instructions
5224 // because they will be either "not lowered" or "all lowered" to branch.
5225 CurInstIterator = std::next(LastSI->getIterator());
5226
5227 bool VectorCond = !SI->getCondition()->getType()->isIntegerTy(1);
2
Assuming the condition is false
5228
5229 // Can we convert the 'select' to CF ?
5230 if (DisableSelectToBranch || OptSize || !TLI || VectorCond ||
3
Assuming the condition is false
4
Assuming the condition is false
5
Assuming the condition is false
6
Taking false branch
5231 SI->getMetadata(LLVMContext::MD_unpredictable))
5232 return false;
5233
5234 TargetLowering::SelectSupportKind SelectKind;
5235 if (VectorCond)
7
Taking false branch
5236 SelectKind = TargetLowering::VectorMaskSelect;
5237 else if (SI->getType()->isVectorTy())
8
Taking false branch
5238 SelectKind = TargetLowering::ScalarCondVectorVal;
5239 else
5240 SelectKind = TargetLowering::ScalarValSelect;
5241
5242 if (TLI->isSelectSupported(SelectKind) &&
9
Assuming the condition is false
5243 !isFormingBranchFromSelectProfitable(TTI, TLI, SI))
5244 return false;
5245
5246 ModifiedDT = true;
5247
5248 // Transform a sequence like this:
5249 // start:
5250 // %cmp = cmp uge i32 %a, %b
5251 // %sel = select i1 %cmp, i32 %c, i32 %d
5252 //
5253 // Into:
5254 // start:
5255 // %cmp = cmp uge i32 %a, %b
5256 // br i1 %cmp, label %select.true, label %select.false
5257 // select.true:
5258 // br label %select.end
5259 // select.false:
5260 // br label %select.end
5261 // select.end:
5262 // %sel = phi i32 [ %c, %select.true ], [ %d, %select.false ]
5263 //
5264 // In addition, we may sink instructions that produce %c or %d from
5265 // the entry block into the destination(s) of the new branch.
5266 // If the true or false blocks do not contain a sunken instruction, that
5267 // block and its branch may be optimized away. In that case, one side of the
5268 // first branch will point directly to select.end, and the corresponding PHI
5269 // predecessor block will be the start block.
5270
5271 // First, we split the block containing the select into 2 blocks.
5272 BasicBlock *StartBlock = SI->getParent();
5273 BasicBlock::iterator SplitPt = ++(BasicBlock::iterator(LastSI));
5274 BasicBlock *EndBlock = StartBlock->splitBasicBlock(SplitPt, "select.end");
5275
5276 // Delete the unconditional branch that was just created by the split.
5277 StartBlock->getTerminator()->eraseFromParent();
5278
5279 // These are the new basic blocks for the conditional branch.
5280 // At least one will become an actual new basic block.
5281 BasicBlock *TrueBlock = nullptr;
5282 BasicBlock *FalseBlock = nullptr;
5283 BranchInst *TrueBranch = nullptr;
5284 BranchInst *FalseBranch = nullptr;
5285
5286 // Sink expensive instructions into the conditional blocks to avoid executing
5287 // them speculatively.
5288 for (SelectInst *SI : ASI) {
10
Assuming '__begin' is equal to '__end'
5289 if (sinkSelectOperand(TTI, SI->getTrueValue())) {
5290 if (TrueBlock == nullptr) {
5291 TrueBlock = BasicBlock::Create(SI->getContext(), "select.true.sink",
5292 EndBlock->getParent(), EndBlock);
5293 TrueBranch = BranchInst::Create(EndBlock, TrueBlock);
5294 }
5295 auto *TrueInst = cast<Instruction>(SI->getTrueValue());
5296 TrueInst->moveBefore(TrueBranch);
5297 }
5298 if (sinkSelectOperand(TTI, SI->getFalseValue())) {
5299 if (FalseBlock == nullptr) {
5300 FalseBlock = BasicBlock::Create(SI->getContext(), "select.false.sink",
5301 EndBlock->getParent(), EndBlock);
5302 FalseBranch = BranchInst::Create(EndBlock, FalseBlock);
5303 }
5304 auto *FalseInst = cast<Instruction>(SI->getFalseValue());
5305 FalseInst->moveBefore(FalseBranch);
5306 }
5307 }
5308
5309 // If there was nothing to sink, then arbitrarily choose the 'false' side
5310 // for a new input value to the PHI.
5311 if (TrueBlock == FalseBlock) {
11
Taking true branch
5312 assert(TrueBlock == nullptr &&((TrueBlock == nullptr && "Unexpected basic block transform while optimizing select"
) ? static_cast<void> (0) : __assert_fail ("TrueBlock == nullptr && \"Unexpected basic block transform while optimizing select\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 5313, __PRETTY_FUNCTION__))
5313 "Unexpected basic block transform while optimizing select")((TrueBlock == nullptr && "Unexpected basic block transform while optimizing select"
) ? static_cast<void> (0) : __assert_fail ("TrueBlock == nullptr && \"Unexpected basic block transform while optimizing select\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 5313, __PRETTY_FUNCTION__))
;
5314
5315 FalseBlock = BasicBlock::Create(SI->getContext(), "select.false",
5316 EndBlock->getParent(), EndBlock);
5317 BranchInst::Create(EndBlock, FalseBlock);
5318 }
5319
5320 // Insert the real conditional branch based on the original condition.
5321 // If we did not create a new block for one of the 'true' or 'false' paths
5322 // of the condition, it means that side of the branch goes to the end block
5323 // directly and the path originates from the start block from the point of
5324 // view of the new PHI.
5325 BasicBlock *TT, *FT;
5326 if (TrueBlock == nullptr) {
12
Taking true branch
5327 TT = EndBlock;
5328 FT = FalseBlock;
5329 TrueBlock = StartBlock;
5330 } else if (FalseBlock == nullptr) {
5331 TT = TrueBlock;
5332 FT = EndBlock;
5333 FalseBlock = StartBlock;
5334 } else {
5335 TT = TrueBlock;
5336 FT = FalseBlock;
5337 }
5338 IRBuilder<>(SI).CreateCondBr(SI->getCondition(), TT, FT, SI);
5339
5340 SmallPtrSet<const Instruction *, 2> INS;
5341 INS.insert(ASI.begin(), ASI.end());
5342 // Use reverse iterator because later select may use the value of the
5343 // earlier select, and we need to propagate value through earlier select
5344 // to get the PHI operand.
5345 for (auto It = ASI.rbegin(); It != ASI.rend(); ++It) {
13
Loop condition is true. Entering loop body
5346 SelectInst *SI = *It;
5347 // The select itself is replaced with a PHI Node.
5348 PHINode *PN = PHINode::Create(SI->getType(), 2, "", &EndBlock->front());
5349 PN->takeName(SI);
5350 PN->addIncoming(getTrueOrFalseValue(SI, true, INS), TrueBlock);
14
Calling 'getTrueOrFalseValue'
5351 PN->addIncoming(getTrueOrFalseValue(SI, false, INS), FalseBlock);
5352
5353 SI->replaceAllUsesWith(PN);
5354 SI->eraseFromParent();
5355 INS.erase(SI);
5356 ++NumSelectsExpanded;
5357 }
5358
5359 // Instruct OptimizeBlock to skip to the next block.
5360 CurInstIterator = StartBlock->end();
5361 return true;
5362}
5363
5364static bool isBroadcastShuffle(ShuffleVectorInst *SVI) {
5365 SmallVector<int, 16> Mask(SVI->getShuffleMask());
5366 int SplatElem = -1;
5367 for (unsigned i = 0; i < Mask.size(); ++i) {
5368 if (SplatElem != -1 && Mask[i] != -1 && Mask[i] != SplatElem)
5369 return false;
5370 SplatElem = Mask[i];
5371 }
5372
5373 return true;
5374}
5375
5376/// Some targets have expensive vector shifts if the lanes aren't all the same
5377/// (e.g. x86 only introduced "vpsllvd" and friends with AVX2). In these cases
5378/// it's often worth sinking a shufflevector splat down to its use so that
5379/// codegen can spot all lanes are identical.
5380bool CodeGenPrepare::optimizeShuffleVectorInst(ShuffleVectorInst *SVI) {
5381 BasicBlock *DefBB = SVI->getParent();
5382
5383 // Only do this xform if variable vector shifts are particularly expensive.
5384 if (!TLI || !TLI->isVectorShiftByScalarCheap(SVI->getType()))
5385 return false;
5386
5387 // We only expect better codegen by sinking a shuffle if we can recognise a
5388 // constant splat.
5389 if (!isBroadcastShuffle(SVI))
5390 return false;
5391
5392 // InsertedShuffles - Only insert a shuffle in each block once.
5393 DenseMap<BasicBlock*, Instruction*> InsertedShuffles;
5394
5395 bool MadeChange = false;
5396 for (User *U : SVI->users()) {
5397 Instruction *UI = cast<Instruction>(U);
5398
5399 // Figure out which BB this ext is used in.
5400 BasicBlock *UserBB = UI->getParent();
5401 if (UserBB == DefBB) continue;
5402
5403 // For now only apply this when the splat is used by a shift instruction.
5404 if (!UI->isShift()) continue;
5405
5406 // Everything checks out, sink the shuffle if the user's block doesn't
5407 // already have a copy.
5408 Instruction *&InsertedShuffle = InsertedShuffles[UserBB];
5409
5410 if (!InsertedShuffle) {
5411 BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
5412 assert(InsertPt != UserBB->end())((InsertPt != UserBB->end()) ? static_cast<void> (0)
: __assert_fail ("InsertPt != UserBB->end()", "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 5412, __PRETTY_FUNCTION__))
;
5413 InsertedShuffle =
5414 new ShuffleVectorInst(SVI->getOperand(0), SVI->getOperand(1),
5415 SVI->getOperand(2), "", &*InsertPt);
5416 }
5417
5418 UI->replaceUsesOfWith(SVI, InsertedShuffle);
5419 MadeChange = true;
5420 }
5421
5422 // If we removed all uses, nuke the shuffle.
5423 if (SVI->use_empty()) {
5424 SVI->eraseFromParent();
5425 MadeChange = true;
5426 }
5427
5428 return MadeChange;
5429}
5430
5431bool CodeGenPrepare::optimizeSwitchInst(SwitchInst *SI) {
5432 if (!TLI || !DL)
5433 return false;
5434
5435 Value *Cond = SI->getCondition();
5436 Type *OldType = Cond->getType();
5437 LLVMContext &Context = Cond->getContext();
5438 MVT RegType = TLI->getRegisterType(Context, TLI->getValueType(*DL, OldType));
5439 unsigned RegWidth = RegType.getSizeInBits();
5440
5441 if (RegWidth <= cast<IntegerType>(OldType)->getBitWidth())
5442 return false;
5443
5444 // If the register width is greater than the type width, expand the condition
5445 // of the switch instruction and each case constant to the width of the
5446 // register. By widening the type of the switch condition, subsequent
5447 // comparisons (for case comparisons) will not need to be extended to the
5448 // preferred register width, so we will potentially eliminate N-1 extends,
5449 // where N is the number of cases in the switch.
5450 auto *NewType = Type::getIntNTy(Context, RegWidth);
5451
5452 // Zero-extend the switch condition and case constants unless the switch
5453 // condition is a function argument that is already being sign-extended.
5454 // In that case, we can avoid an unnecessary mask/extension by sign-extending
5455 // everything instead.
5456 Instruction::CastOps ExtType = Instruction::ZExt;
5457 if (auto *Arg = dyn_cast<Argument>(Cond))
5458 if (Arg->hasSExtAttr())
5459 ExtType = Instruction::SExt;
5460
5461 auto *ExtInst = CastInst::Create(ExtType, Cond, NewType);
5462 ExtInst->insertBefore(SI);
5463 SI->setCondition(ExtInst);
5464 for (auto Case : SI->cases()) {
5465 APInt NarrowConst = Case.getCaseValue()->getValue();
5466 APInt WideConst = (ExtType == Instruction::ZExt) ?
5467 NarrowConst.zext(RegWidth) : NarrowConst.sext(RegWidth);
5468 Case.setValue(ConstantInt::get(Context, WideConst));
5469 }
5470
5471 return true;
5472}
5473
5474namespace {
5475/// \brief Helper class to promote a scalar operation to a vector one.
5476/// This class is used to move downward extractelement transition.
5477/// E.g.,
5478/// a = vector_op <2 x i32>
5479/// b = extractelement <2 x i32> a, i32 0
5480/// c = scalar_op b
5481/// store c
5482///
5483/// =>
5484/// a = vector_op <2 x i32>
5485/// c = vector_op a (equivalent to scalar_op on the related lane)
5486/// * d = extractelement <2 x i32> c, i32 0
5487/// * store d
5488/// Assuming both extractelement and store can be combine, we get rid of the
5489/// transition.
5490class VectorPromoteHelper {
5491 /// DataLayout associated with the current module.
5492 const DataLayout &DL;
5493
5494 /// Used to perform some checks on the legality of vector operations.
5495 const TargetLowering &TLI;
5496
5497 /// Used to estimated the cost of the promoted chain.
5498 const TargetTransformInfo &TTI;
5499
5500 /// The transition being moved downwards.
5501 Instruction *Transition;
5502 /// The sequence of instructions to be promoted.
5503 SmallVector<Instruction *, 4> InstsToBePromoted;
5504 /// Cost of combining a store and an extract.
5505 unsigned StoreExtractCombineCost;
5506 /// Instruction that will be combined with the transition.
5507 Instruction *CombineInst;
5508
5509 /// \brief The instruction that represents the current end of the transition.
5510 /// Since we are faking the promotion until we reach the end of the chain
5511 /// of computation, we need a way to get the current end of the transition.
5512 Instruction *getEndOfTransition() const {
5513 if (InstsToBePromoted.empty())
5514 return Transition;
5515 return InstsToBePromoted.back();
5516 }
5517
5518 /// \brief Return the index of the original value in the transition.
5519 /// E.g., for "extractelement <2 x i32> c, i32 1" the original value,
5520 /// c, is at index 0.
5521 unsigned getTransitionOriginalValueIdx() const {
5522 assert(isa<ExtractElementInst>(Transition) &&((isa<ExtractElementInst>(Transition) && "Other kind of transitions are not supported yet"
) ? static_cast<void> (0) : __assert_fail ("isa<ExtractElementInst>(Transition) && \"Other kind of transitions are not supported yet\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 5523, __PRETTY_FUNCTION__))
5523 "Other kind of transitions are not supported yet")((isa<ExtractElementInst>(Transition) && "Other kind of transitions are not supported yet"
) ? static_cast<void> (0) : __assert_fail ("isa<ExtractElementInst>(Transition) && \"Other kind of transitions are not supported yet\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 5523, __PRETTY_FUNCTION__))
;
5524 return 0;
5525 }
5526
5527 /// \brief Return the index of the index in the transition.
5528 /// E.g., for "extractelement <2 x i32> c, i32 0" the index
5529 /// is at index 1.
5530 unsigned getTransitionIdx() const {
5531 assert(isa<ExtractElementInst>(Transition) &&((isa<ExtractElementInst>(Transition) && "Other kind of transitions are not supported yet"
) ? static_cast<void> (0) : __assert_fail ("isa<ExtractElementInst>(Transition) && \"Other kind of transitions are not supported yet\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 5532, __PRETTY_FUNCTION__))
5532 "Other kind of transitions are not supported yet")((isa<ExtractElementInst>(Transition) && "Other kind of transitions are not supported yet"
) ? static_cast<void> (0) : __assert_fail ("isa<ExtractElementInst>(Transition) && \"Other kind of transitions are not supported yet\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 5532, __PRETTY_FUNCTION__))
;
5533 return 1;
5534 }
5535
5536 /// \brief Get the type of the transition.
5537 /// This is the type of the original value.
5538 /// E.g., for "extractelement <2 x i32> c, i32 1" the type of the
5539 /// transition is <2 x i32>.
5540 Type *getTransitionType() const {
5541 return Transition->getOperand(getTransitionOriginalValueIdx())->getType();
5542 }
5543
5544 /// \brief Promote \p ToBePromoted by moving \p Def downward through.
5545 /// I.e., we have the following sequence:
5546 /// Def = Transition <ty1> a to <ty2>
5547 /// b = ToBePromoted <ty2> Def, ...
5548 /// =>
5549 /// b = ToBePromoted <ty1> a, ...
5550 /// Def = Transition <ty1> ToBePromoted to <ty2>
5551 void promoteImpl(Instruction *ToBePromoted);
5552
5553 /// \brief Check whether or not it is profitable to promote all the
5554 /// instructions enqueued to be promoted.
5555 bool isProfitableToPromote() {
5556 Value *ValIdx = Transition->getOperand(getTransitionOriginalValueIdx());
5557 unsigned Index = isa<ConstantInt>(ValIdx)
5558 ? cast<ConstantInt>(ValIdx)->getZExtValue()
5559 : -1;
5560 Type *PromotedType = getTransitionType();
5561
5562 StoreInst *ST = cast<StoreInst>(CombineInst);
5563 unsigned AS = ST->getPointerAddressSpace();
5564 unsigned Align = ST->getAlignment();
5565 // Check if this store is supported.
5566 if (!TLI.allowsMisalignedMemoryAccesses(
5567 TLI.getValueType(DL, ST->getValueOperand()->getType()), AS,
5568 Align)) {
5569 // If this is not supported, there is no way we can combine
5570 // the extract with the store.
5571 return false;
5572 }
5573
5574 // The scalar chain of computation has to pay for the transition
5575 // scalar to vector.
5576 // The vector chain has to account for the combining cost.
5577 uint64_t ScalarCost =
5578 TTI.getVectorInstrCost(Transition->getOpcode(), PromotedType, Index);
5579 uint64_t VectorCost = StoreExtractCombineCost;
5580 for (const auto &Inst : InstsToBePromoted) {
5581 // Compute the cost.
5582 // By construction, all instructions being promoted are arithmetic ones.
5583 // Moreover, one argument is a constant that can be viewed as a splat
5584 // constant.
5585 Value *Arg0 = Inst->getOperand(0);
5586 bool IsArg0Constant = isa<UndefValue>(Arg0) || isa<ConstantInt>(Arg0) ||
5587 isa<ConstantFP>(Arg0);
5588 TargetTransformInfo::OperandValueKind Arg0OVK =
5589 IsArg0Constant ? TargetTransformInfo::OK_UniformConstantValue
5590 : TargetTransformInfo::OK_AnyValue;
5591 TargetTransformInfo::OperandValueKind Arg1OVK =
5592 !IsArg0Constant ? TargetTransformInfo::OK_UniformConstantValue
5593 : TargetTransformInfo::OK_AnyValue;
5594 ScalarCost += TTI.getArithmeticInstrCost(
5595 Inst->getOpcode(), Inst->getType(), Arg0OVK, Arg1OVK);
5596 VectorCost += TTI.getArithmeticInstrCost(Inst->getOpcode(), PromotedType,
5597 Arg0OVK, Arg1OVK);
5598 }
5599 DEBUG(dbgs() << "Estimated cost of computation to be promoted:\nScalar: "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Estimated cost of computation to be promoted:\nScalar: "
<< ScalarCost << "\nVector: " << VectorCost
<< '\n'; } } while (false)
5600 << ScalarCost << "\nVector: " << VectorCost << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Estimated cost of computation to be promoted:\nScalar: "
<< ScalarCost << "\nVector: " << VectorCost
<< '\n'; } } while (false)
;
5601 return ScalarCost > VectorCost;
5602 }
5603
5604 /// \brief Generate a constant vector with \p Val with the same
5605 /// number of elements as the transition.
5606 /// \p UseSplat defines whether or not \p Val should be replicated
5607 /// across the whole vector.
5608 /// In other words, if UseSplat == true, we generate <Val, Val, ..., Val>,
5609 /// otherwise we generate a vector with as many undef as possible:
5610 /// <undef, ..., undef, Val, undef, ..., undef> where \p Val is only
5611 /// used at the index of the extract.
5612 Value *getConstantVector(Constant *Val, bool UseSplat) const {
5613 unsigned ExtractIdx = UINT_MAX(2147483647 *2U +1U);
5614 if (!UseSplat) {
5615 // If we cannot determine where the constant must be, we have to
5616 // use a splat constant.
5617 Value *ValExtractIdx = Transition->getOperand(getTransitionIdx());
5618 if (ConstantInt *CstVal = dyn_cast<ConstantInt>(ValExtractIdx))
5619 ExtractIdx = CstVal->getSExtValue();
5620 else
5621 UseSplat = true;
5622 }
5623
5624 unsigned End = getTransitionType()->getVectorNumElements();
5625 if (UseSplat)
5626 return ConstantVector::getSplat(End, Val);
5627
5628 SmallVector<Constant *, 4> ConstVec;
5629 UndefValue *UndefVal = UndefValue::get(Val->getType());
5630 for (unsigned Idx = 0; Idx != End; ++Idx) {
5631 if (Idx == ExtractIdx)
5632 ConstVec.push_back(Val);
5633 else
5634 ConstVec.push_back(UndefVal);
5635 }
5636 return ConstantVector::get(ConstVec);
5637 }
5638
5639 /// \brief Check if promoting to a vector type an operand at \p OperandIdx
5640 /// in \p Use can trigger undefined behavior.
5641 static bool canCauseUndefinedBehavior(const Instruction *Use,
5642 unsigned OperandIdx) {
5643 // This is not safe to introduce undef when the operand is on
5644 // the right hand side of a division-like instruction.
5645 if (OperandIdx != 1)
5646 return false;
5647 switch (Use->getOpcode()) {
5648 default:
5649 return false;
5650 case Instruction::SDiv:
5651 case Instruction::UDiv:
5652 case Instruction::SRem:
5653 case Instruction::URem:
5654 return true;
5655 case Instruction::FDiv:
5656 case Instruction::FRem:
5657 return !Use->hasNoNaNs();
5658 }
5659 llvm_unreachable(nullptr)::llvm::llvm_unreachable_internal(nullptr, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 5659)
;
5660 }
5661
5662public:
5663 VectorPromoteHelper(const DataLayout &DL, const TargetLowering &TLI,
5664 const TargetTransformInfo &TTI, Instruction *Transition,
5665 unsigned CombineCost)
5666 : DL(DL), TLI(TLI), TTI(TTI), Transition(Transition),
5667 StoreExtractCombineCost(CombineCost), CombineInst(nullptr) {
5668 assert(Transition && "Do not know how to promote null")((Transition && "Do not know how to promote null") ? static_cast
<void> (0) : __assert_fail ("Transition && \"Do not know how to promote null\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 5668, __PRETTY_FUNCTION__))
;
5669 }
5670
5671 /// \brief Check if we can promote \p ToBePromoted to \p Type.
5672 bool canPromote(const Instruction *ToBePromoted) const {
5673 // We could support CastInst too.
5674 return isa<BinaryOperator>(ToBePromoted);
5675 }
5676
5677 /// \brief Check if it is profitable to promote \p ToBePromoted
5678 /// by moving downward the transition through.
5679 bool shouldPromote(const Instruction *ToBePromoted) const {
5680 // Promote only if all the operands can be statically expanded.
5681 // Indeed, we do not want to introduce any new kind of transitions.
5682 for (const Use &U : ToBePromoted->operands()) {
5683 const Value *Val = U.get();
5684 if (Val == getEndOfTransition()) {
5685 // If the use is a division and the transition is on the rhs,
5686 // we cannot promote the operation, otherwise we may create a
5687 // division by zero.
5688 if (canCauseUndefinedBehavior(ToBePromoted, U.getOperandNo()))
5689 return false;
5690 continue;
5691 }
5692 if (!isa<ConstantInt>(Val) && !isa<UndefValue>(Val) &&
5693 !isa<ConstantFP>(Val))
5694 return false;
5695 }
5696 // Check that the resulting operation is legal.
5697 int ISDOpcode = TLI.InstructionOpcodeToISD(ToBePromoted->getOpcode());
5698 if (!ISDOpcode)
5699 return false;
5700 return StressStoreExtract ||
5701 TLI.isOperationLegalOrCustom(
5702 ISDOpcode, TLI.getValueType(DL, getTransitionType(), true));
5703 }
5704
5705 /// \brief Check whether or not \p Use can be combined
5706 /// with the transition.
5707 /// I.e., is it possible to do Use(Transition) => AnotherUse?
5708 bool canCombine(const Instruction *Use) { return isa<StoreInst>(Use); }
5709
5710 /// \brief Record \p ToBePromoted as part of the chain to be promoted.
5711 void enqueueForPromotion(Instruction *ToBePromoted) {
5712 InstsToBePromoted.push_back(ToBePromoted);
5713 }
5714
5715 /// \brief Set the instruction that will be combined with the transition.
5716 void recordCombineInstruction(Instruction *ToBeCombined) {
5717 assert(canCombine(ToBeCombined) && "Unsupported instruction to combine")((canCombine(ToBeCombined) && "Unsupported instruction to combine"
) ? static_cast<void> (0) : __assert_fail ("canCombine(ToBeCombined) && \"Unsupported instruction to combine\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 5717, __PRETTY_FUNCTION__))
;
5718 CombineInst = ToBeCombined;
5719 }
5720
5721 /// \brief Promote all the instructions enqueued for promotion if it is
5722 /// is profitable.
5723 /// \return True if the promotion happened, false otherwise.
5724 bool promote() {
5725 // Check if there is something to promote.
5726 // Right now, if we do not have anything to combine with,
5727 // we assume the promotion is not profitable.
5728 if (InstsToBePromoted.empty() || !CombineInst)
5729 return false;
5730
5731 // Check cost.
5732 if (!StressStoreExtract && !isProfitableToPromote())
5733 return false;
5734
5735 // Promote.
5736 for (auto &ToBePromoted : InstsToBePromoted)
5737 promoteImpl(ToBePromoted);
5738 InstsToBePromoted.clear();
5739 return true;
5740 }
5741};
5742} // End of anonymous namespace.
5743
5744void VectorPromoteHelper::promoteImpl(Instruction *ToBePromoted) {
5745 // At this point, we know that all the operands of ToBePromoted but Def
5746 // can be statically promoted.
5747 // For Def, we need to use its parameter in ToBePromoted:
5748 // b = ToBePromoted ty1 a
5749 // Def = Transition ty1 b to ty2
5750 // Move the transition down.
5751 // 1. Replace all uses of the promoted operation by the transition.
5752 // = ... b => = ... Def.
5753 assert(ToBePromoted->getType() == Transition->getType() &&((ToBePromoted->getType() == Transition->getType() &&
"The type of the result of the transition does not match " "the final type"
) ? static_cast<void> (0) : __assert_fail ("ToBePromoted->getType() == Transition->getType() && \"The type of the result of the transition does not match \" \"the final type\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 5755, __PRETTY_FUNCTION__))
5754 "The type of the result of the transition does not match "((ToBePromoted->getType() == Transition->getType() &&
"The type of the result of the transition does not match " "the final type"
) ? static_cast<void> (0) : __assert_fail ("ToBePromoted->getType() == Transition->getType() && \"The type of the result of the transition does not match \" \"the final type\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 5755, __PRETTY_FUNCTION__))
5755 "the final type")((ToBePromoted->getType() == Transition->getType() &&
"The type of the result of the transition does not match " "the final type"
) ? static_cast<void> (0) : __assert_fail ("ToBePromoted->getType() == Transition->getType() && \"The type of the result of the transition does not match \" \"the final type\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 5755, __PRETTY_FUNCTION__))
;
5756 ToBePromoted->replaceAllUsesWith(Transition);
5757 // 2. Update the type of the uses.
5758 // b = ToBePromoted ty2 Def => b = ToBePromoted ty1 Def.
5759 Type *TransitionTy = getTransitionType();
5760 ToBePromoted->mutateType(TransitionTy);
5761 // 3. Update all the operands of the promoted operation with promoted
5762 // operands.
5763 // b = ToBePromoted ty1 Def => b = ToBePromoted ty1 a.
5764 for (Use &U : ToBePromoted->operands()) {
5765 Value *Val = U.get();
5766 Value *NewVal = nullptr;
5767 if (Val == Transition)
5768 NewVal = Transition->getOperand(getTransitionOriginalValueIdx());
5769 else if (isa<UndefValue>(Val) || isa<ConstantInt>(Val) ||
5770 isa<ConstantFP>(Val)) {
5771 // Use a splat constant if it is not safe to use undef.
5772 NewVal = getConstantVector(
5773 cast<Constant>(Val),
5774 isa<UndefValue>(Val) ||
5775 canCauseUndefinedBehavior(ToBePromoted, U.getOperandNo()));
5776 } else
5777 llvm_unreachable("Did you modified shouldPromote and forgot to update "::llvm::llvm_unreachable_internal("Did you modified shouldPromote and forgot to update "
"this?", "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 5778)
5778 "this?")::llvm::llvm_unreachable_internal("Did you modified shouldPromote and forgot to update "
"this?", "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301135/lib/CodeGen/CodeGenPrepare.cpp"
, 5778)
;
5779 ToBePromoted->setOperand(U.getOperandNo(), NewVal);
5780 }
5781 Transition->removeFromParent();
5782 Transition->insertAfter(ToBePromoted);
5783 Transition->setOperand(getTransitionOriginalValueIdx(), ToBePromoted);
5784}
5785
5786/// Some targets can do store(extractelement) with one instruction.
5787/// Try to push the extractelement towards the stores when the target
5788/// has this feature and this is profitable.
5789bool CodeGenPrepare::optimizeExtractElementInst(Instruction *Inst) {
5790 unsigned CombineCost = UINT_MAX(2147483647 *2U +1U);
5791 if (DisableStoreExtract || !TLI ||
5792 (!StressStoreExtract &&
5793 !TLI->canCombineStoreAndExtract(Inst->getOperand(0)->getType(),
5794 Inst->getOperand(1), CombineCost)))
5795 return false;
5796
5797 // At this point we know that Inst is a vector to scalar transition.
5798 // Try to move it down the def-use chain, until:
5799 // - We can combine the transition with its single use
5800 // => we got rid of the transition.
5801 // - We escape the current basic block
5802 // => we would need to check that we are moving it at a cheaper place and
5803 // we do not do that for now.
5804 BasicBlock *Parent = Inst->getParent();
5805 DEBUG(dbgs() << "Found an interesting transition: " << *Inst << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Found an interesting transition: "
<< *Inst << '\n'; } } while (false)
;
5806 VectorPromoteHelper VPH(*DL, *TLI, *TTI, Inst, CombineCost);
5807 // If the transition has more than one use, assume this is not going to be
5808 // beneficial.
5809 while (Inst->hasOneUse()) {
5810 Instruction *ToBePromoted = cast<Instruction>(*Inst->user_begin());
5811 DEBUG(dbgs() << "Use: " << *ToBePromoted << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Use: " << *ToBePromoted
<< '\n'; } } while (false)
;
5812
5813 if (ToBePromoted->getParent() != Parent) {
5814 DEBUG(dbgs() << "Instruction to promote is in a different block ("do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Instruction to promote is in a different block ("
<< ToBePromoted->getParent()->getName() <<
") than the transition (" << Parent->getName() <<
").\n"; } } while (false)
5815 << ToBePromoted->getParent()->getName()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Instruction to promote is in a different block ("
<< ToBePromoted->getParent()->getName() <<
") than the transition (" << Parent->getName() <<
").\n"; } } while (false)
5816 << ") than the transition (" << Parent->getName() << ").\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Instruction to promote is in a different block ("
<< ToBePromoted->getParent()->getName() <<
") than the transition (" << Parent->getName() <<
").\n"; } } while (false)
;
5817 return false;
5818 }
5819
5820 if (VPH.canCombine(ToBePromoted)) {
5821 DEBUG(dbgs() << "Assume " << *Inst << '\n'do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Assume " << *Inst
<< '\n' << "will be combined with: " << *ToBePromoted
<< '\n'; } } while (false)
5822 << "will be combined with: " << *ToBePromoted << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Assume " << *Inst
<< '\n' << "will be combined with: " << *ToBePromoted
<< '\n'; } } while (false)
;
5823 VPH.recordCombineInstruction(ToBePromoted);
5824 bool Changed = VPH.promote();
5825 NumStoreExtractExposed += Changed;
5826 return Changed;
5827 }
5828
5829 DEBUG(dbgs() << "Try promoting.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Try promoting.\n"; } }
while (false)
;
5830 if (!VPH.canPromote(ToBePromoted) || !VPH.shouldPromote(ToBePromoted))
5831 return false;
5832
5833 DEBUG(dbgs() << "Promoting is possible... Enqueue for promotion!\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Promoting is possible... Enqueue for promotion!\n"
; } } while (false)
;
5834
5835 VPH.enqueueForPromotion(ToBePromoted);
5836 Inst = ToBePromoted;
5837 }
5838 return false;
5839}
5840
5841/// For the instruction sequence of store below, F and I values
5842/// are bundled together as an i64 value before being stored into memory.
5843/// Sometimes it is more efficent to generate separate stores for F and I,
5844/// which can remove the bitwise instructions or sink them to colder places.
5845///
5846/// (store (or (zext (bitcast F to i32) to i64),
5847/// (shl (zext I to i64), 32)), addr) -->
5848/// (store F, addr) and (store I, addr+4)
5849///
5850/// Similarly, splitting for other merged store can also be beneficial, like:
5851/// For pair of {i32, i32}, i64 store --> two i32 stores.
5852/// For pair of {i32, i16}, i64 store --> two i32 stores.
5853/// For pair of {i16, i16}, i32 store --> two i16 stores.
5854/// For pair of {i16, i8}, i32 store --> two i16 stores.
5855/// For pair of {i8, i8}, i16 store --> two i8 stores.
5856///
5857/// We allow each target to determine specifically which kind of splitting is
5858/// supported.
5859///
5860/// The store patterns are commonly seen from the simple code snippet below
5861/// if only std::make_pair(...) is sroa transformed before inlined into hoo.
5862/// void goo(const std::pair<int, float> &);
5863/// hoo() {
5864/// ...
5865/// goo(std::make_pair(tmp, ftmp));
5866/// ...
5867/// }
5868///
5869/// Although we already have similar splitting in DAG Combine, we duplicate
5870/// it in CodeGenPrepare to catch the case in which pattern is across
5871/// multiple BBs. The logic in DAG Combine is kept to catch case generated
5872/// during code expansion.
5873static bool splitMergedValStore(StoreInst &SI, const DataLayout &DL,
5874 const TargetLowering &TLI) {
5875 // Handle simple but common cases only.
5876 Type *StoreType = SI.getValueOperand()->getType();
5877 if (DL.getTypeStoreSizeInBits(StoreType) != DL.getTypeSizeInBits(StoreType) ||
5878 DL.getTypeSizeInBits(StoreType) == 0)
5879 return false;
5880
5881 unsigned HalfValBitSize = DL.getTypeSizeInBits(StoreType) / 2;
5882 Type *SplitStoreType = Type::getIntNTy(SI.getContext(), HalfValBitSize);
5883 if (DL.getTypeStoreSizeInBits(SplitStoreType) !=
5884 DL.getTypeSizeInBits(SplitStoreType))
5885 return false;
5886
5887 // Match the following patterns:
5888 // (store (or (zext LValue to i64),
5889 // (shl (zext HValue to i64), 32)), HalfValBitSize)
5890 // or
5891 // (store (or (shl (zext HValue to i64), 32)), HalfValBitSize)
5892 // (zext LValue to i64),
5893 // Expect both operands of OR and the first operand of SHL have only
5894 // one use.
5895 Value *LValue, *HValue;
5896 if (!match(SI.getValueOperand(),
5897 m_c_Or(m_OneUse(m_ZExt(m_Value(LValue))),
5898 m_OneUse(m_Shl(m_OneUse(m_ZExt(m_Value(HValue))),
5899 m_SpecificInt(HalfValBitSize))))))
5900 return false;
5901
5902 // Check LValue and HValue are int with size less or equal than 32.
5903 if (!LValue->getType()->isIntegerTy() ||
5904 DL.getTypeSizeInBits(LValue->getType()) > HalfValBitSize ||
5905 !HValue->getType()->isIntegerTy() ||
5906 DL.getTypeSizeInBits(HValue->getType()) > HalfValBitSize)
5907 return false;
5908
5909 // If LValue/HValue is a bitcast instruction, use the EVT before bitcast
5910 // as the input of target query.
5911 auto *LBC = dyn_cast<BitCastInst>(LValue);
5912 auto *HBC = dyn_cast<BitCastInst>(HValue);
5913 EVT LowTy = LBC ? EVT::getEVT(LBC->getOperand(0)->getType())
5914 : EVT::getEVT(LValue->getType());
5915 EVT HighTy = HBC ? EVT::getEVT(HBC->getOperand(0)->getType())
5916 : EVT::getEVT(HValue->getType());
5917 if (!ForceSplitStore && !TLI.isMultiStoresCheaperThanBitsMerge(LowTy, HighTy))
5918 return false;
5919
5920 // Start to split store.
5921 IRBuilder<> Builder(SI.getContext());
5922 Builder.SetInsertPoint(&SI);
5923
5924 // If LValue/HValue is a bitcast in another BB, create a new one in current
5925 // BB so it may be merged with the splitted stores by dag combiner.
5926 if (LBC && LBC->getParent() != SI.getParent())
5927 LValue = Builder.CreateBitCast(LBC->getOperand(0), LBC->getType());
5928 if (HBC && HBC->getParent() != SI.getParent())
5929 HValue = Builder.CreateBitCast(HBC->getOperand(0), HBC->getType());
5930
5931 auto CreateSplitStore = [&](Value *V, bool Upper) {
5932 V = Builder.CreateZExtOrBitCast(V, SplitStoreType);
5933 Value *Addr = Builder.CreateBitCast(
5934 SI.getOperand(1),
5935 SplitStoreType->getPointerTo(SI.getPointerAddressSpace()));
5936 if (Upper)
5937 Addr = Builder.CreateGEP(
5938 SplitStoreType, Addr,
5939 ConstantInt::get(Type::getInt32Ty(SI.getContext()), 1));
5940 Builder.CreateAlignedStore(
5941 V, Addr, Upper ? SI.getAlignment() / 2 : SI.getAlignment());
5942 };
5943
5944 CreateSplitStore(LValue, false);
5945 CreateSplitStore(HValue, true);
5946
5947 // Delete the old store.
5948 SI.eraseFromParent();
5949 return true;
5950}
5951
5952bool CodeGenPrepare::optimizeInst(Instruction *I, bool& ModifiedDT) {
5953 // Bail out if we inserted the instruction to prevent optimizations from
5954 // stepping on each other's toes.
5955 if (InsertedInsts.count(I))
5956 return false;
5957
5958 if (PHINode *P = dyn_cast<PHINode>(I)) {
5959 // It is possible for very late stage optimizations (such as SimplifyCFG)
5960 // to introduce PHI nodes too late to be cleaned up. If we detect such a
5961 // trivial PHI, go ahead and zap it here.
5962 if (Value *V = SimplifyInstruction(P, *DL, TLInfo, nullptr)) {
5963 P->replaceAllUsesWith(V);
5964 P->eraseFromParent();
5965 ++NumPHIsElim;
5966 return true;
5967 }
5968 return false;
5969 }
5970
5971 if (CastInst *CI = dyn_cast<CastInst>(I)) {
5972 // If the source of the cast is a constant, then this should have
5973 // already been constant folded. The only reason NOT to constant fold
5974 // it is if something (e.g. LSR) was careful to place the constant
5975 // evaluation in a block other than then one that uses it (e.g. to hoist
5976 // the address of globals out of a loop). If this is the case, we don't
5977 // want to forward-subst the cast.
5978 if (isa<Constant>(CI->getOperand(0)))
5979 return false;
5980
5981 if (TLI && OptimizeNoopCopyExpression(CI, *TLI, *DL))
5982 return true;
5983
5984 if (isa<ZExtInst>(I) || isa<SExtInst>(I)) {
5985 /// Sink a zext or sext into its user blocks if the target type doesn't
5986 /// fit in one register
5987 if (TLI &&
5988 TLI->getTypeAction(CI->getContext(),
5989 TLI->getValueType(*DL, CI->getType())) ==
5990 TargetLowering::TypeExpandInteger) {
5991 return SinkCast(CI);
5992 } else {
5993 bool MadeChange = optimizeExt(I);
5994 return MadeChange | optimizeExtUses(I);
5995 }
5996 }
5997 return false;
5998 }
5999
6000 if (CmpInst *CI = dyn_cast<CmpInst>(I))
6001 if (!TLI || !TLI->hasMultipleConditionRegisters())
6002 return OptimizeCmpExpression(CI, TLI);
6003
6004 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
6005 LI->setMetadata(LLVMContext::MD_invariant_group, nullptr);
6006 if (TLI) {
6007 bool Modified = optimizeLoadExt(LI);
6008 unsigned AS = LI->getPointerAddressSpace();
6009 Modified |= optimizeMemoryInst(I, I->getOperand(0), LI->getType(), AS);
6010 return Modified;
6011 }
6012 return false;
6013 }
6014
6015 if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
6016 if (TLI && splitMergedValStore(*SI, *DL, *TLI))
6017 return true;
6018 SI->setMetadata(LLVMContext::MD_invariant_group, nullptr);
6019 if (TLI) {
6020 unsigned AS = SI->getPointerAddressSpace();
6021 return optimizeMemoryInst(I, SI->getOperand(1),
6022 SI->getOperand(0)->getType(), AS);
6023 }
6024 return false;
6025 }
6026
6027 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
6028 unsigned AS = RMW->getPointerAddressSpace();
6029 return optimizeMemoryInst(I, RMW->getPointerOperand(),
6030 RMW->getType(), AS);
6031 }
6032
6033 if (AtomicCmpXchgInst *CmpX = dyn_cast<AtomicCmpXchgInst>(I)) {
6034 unsigned AS = CmpX->getPointerAddressSpace();
6035 return optimizeMemoryInst(I, CmpX->getPointerOperand(),
6036 CmpX->getCompareOperand()->getType(), AS);
6037 }
6038
6039 BinaryOperator *BinOp = dyn_cast<BinaryOperator>(I);
6040
6041 if (BinOp && (BinOp->getOpcode() == Instruction::And) &&
6042 EnableAndCmpSinking && TLI)
6043 return sinkAndCmp0Expression(BinOp, *TLI, InsertedInsts);
6044
6045 if (BinOp && (BinOp->getOpcode() == Instruction::AShr ||
6046 BinOp->getOpcode() == Instruction::LShr)) {
6047 ConstantInt *CI = dyn_cast<ConstantInt>(BinOp->getOperand(1));
6048 if (TLI && CI && TLI->hasExtractBitsInsn())
6049 return OptimizeExtractBits(BinOp, CI, *TLI, *DL);
6050
6051 return false;
6052 }
6053
6054 if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(I)) {
6055 if (GEPI->hasAllZeroIndices()) {
6056 /// The GEP operand must be a pointer, so must its result -> BitCast
6057 Instruction *NC = new BitCastInst(GEPI->getOperand(0), GEPI->getType(),
6058 GEPI->getName(), GEPI);
6059 GEPI->replaceAllUsesWith(NC);
6060 GEPI->eraseFromParent();
6061 ++NumGEPsElim;
6062 optimizeInst(NC, ModifiedDT);
6063 return true;
6064 }
6065 return false;
6066 }
6067
6068 if (CallInst *CI = dyn_cast<CallInst>(I))
6069 return optimizeCallInst(CI, ModifiedDT);
6070
6071 if (SelectInst *SI = dyn_cast<SelectInst>(I))
6072 return optimizeSelectInst(SI);
6073
6074 if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(I))
6075 return optimizeShuffleVectorInst(SVI);
6076
6077 if (auto *Switch = dyn_cast<SwitchInst>(I))
6078 return optimizeSwitchInst(Switch);
6079
6080 if (isa<ExtractElementInst>(I))
6081 return optimizeExtractElementInst(I);
6082
6083 return false;
6084}
6085
6086/// Given an OR instruction, check to see if this is a bitreverse
6087/// idiom. If so, insert the new intrinsic and return true.
6088static bool makeBitReverse(Instruction &I, const DataLayout &DL,
6089 const TargetLowering &TLI) {
6090 if (!I.getType()->isIntegerTy() ||
6091 !TLI.isOperationLegalOrCustom(ISD::BITREVERSE,
6092 TLI.getValueType(DL, I.getType(), true)))
6093 return false;
6094
6095 SmallVector<Instruction*, 4> Insts;
6096 if (!recognizeBSwapOrBitReverseIdiom(&I, false, true, Insts))
6097 return false;
6098 Instruction *LastInst = Insts.back();
6099 I.replaceAllUsesWith(LastInst);
6100 RecursivelyDeleteTriviallyDeadInstructions(&I);
6101 return true;
6102}
6103
6104// In this pass we look for GEP and cast instructions that are used
6105// across basic blocks and rewrite them to improve basic-block-at-a-time
6106// selection.
6107bool CodeGenPrepare::optimizeBlock(BasicBlock &BB, bool& ModifiedDT) {
6108 SunkAddrs.clear();
6109 bool MadeChange = false;
6110
6111 CurInstIterator = BB.begin();
6112 while (CurInstIterator != BB.end()) {
6113 MadeChange |= optimizeInst(&*CurInstIterator++, ModifiedDT);
6114 if (ModifiedDT)
6115 return true;
6116 }
6117
6118 bool MadeBitReverse = true;
6119 while (TLI && MadeBitReverse) {
6120 MadeBitReverse = false;
6121 for (auto &I : reverse(BB)) {
6122 if (makeBitReverse(I, *DL, *TLI)) {
6123 MadeBitReverse = MadeChange = true;
6124 ModifiedDT = true;
6125 break;
6126 }
6127 }
6128 }
6129 MadeChange |= dupRetToEnableTailCallOpts(&BB);
6130
6131 return MadeChange;
6132}
6133
6134// llvm.dbg.value is far away from the value then iSel may not be able
6135// handle it properly. iSel will drop llvm.dbg.value if it can not
6136// find a node corresponding to the value.
6137bool CodeGenPrepare::placeDbgValues(Function &F) {
6138 bool MadeChange = false;
6139 for (BasicBlock &BB : F) {
6140 Instruction *PrevNonDbgInst = nullptr;
6141 for (BasicBlock::iterator BI = BB.begin(), BE = BB.end(); BI != BE;) {
6142 Instruction *Insn = &*BI++;
6143 DbgValueInst *DVI = dyn_cast<DbgValueInst>(Insn);
6144 // Leave dbg.values that refer to an alloca alone. These
6145 // instrinsics describe the address of a variable (= the alloca)
6146 // being taken. They should not be moved next to the alloca
6147 // (and to the beginning of the scope), but rather stay close to
6148 // where said address is used.
6149 if (!DVI || (DVI->getValue() && isa<AllocaInst>(DVI->getValue()))) {
6150 PrevNonDbgInst = Insn;
6151 continue;
6152 }
6153
6154 Instruction *VI = dyn_cast_or_null<Instruction>(DVI->getValue());
6155 if (VI && VI != PrevNonDbgInst && !VI->isTerminator()) {
6156 // If VI is a phi in a block with an EHPad terminator, we can't insert
6157 // after it.
6158 if (isa<PHINode>(VI) && VI->getParent()->getTerminator()->isEHPad())
6159 continue;
6160 DEBUG(dbgs() << "Moving Debug Value before :\n" << *DVI << ' ' << *VI)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Moving Debug Value before :\n"
<< *DVI << ' ' << *VI; } } while (false)
;
6161 DVI->removeFromParent();
6162 if (isa<PHINode>(VI))
6163 DVI->insertBefore(&*VI->getParent()->getFirstInsertionPt());
6164 else
6165 DVI->insertAfter(VI);
6166 MadeChange = true;
6167 ++NumDbgValueMoved;
6168 }
6169 }
6170 }
6171 return MadeChange;
6172}
6173
6174/// \brief Scale down both weights to fit into uint32_t.
6175static void scaleWeights(uint64_t &NewTrue, uint64_t &NewFalse) {
6176 uint64_t NewMax = (NewTrue > NewFalse) ? NewTrue : NewFalse;
6177 uint32_t Scale = (NewMax / UINT32_MAX(4294967295U)) + 1;
6178 NewTrue = NewTrue / Scale;
6179 NewFalse = NewFalse / Scale;
6180}
6181
6182/// \brief Some targets prefer to split a conditional branch like:
6183/// \code
6184/// %0 = icmp ne i32 %a, 0
6185/// %1 = icmp ne i32 %b, 0
6186/// %or.cond = or i1 %0, %1
6187/// br i1 %or.cond, label %TrueBB, label %FalseBB
6188/// \endcode
6189/// into multiple branch instructions like:
6190/// \code
6191/// bb1:
6192/// %0 = icmp ne i32 %a, 0
6193/// br i1 %0, label %TrueBB, label %bb2
6194/// bb2:
6195/// %1 = icmp ne i32 %b, 0
6196/// br i1 %1, label %TrueBB, label %FalseBB
6197/// \endcode
6198/// This usually allows instruction selection to do even further optimizations
6199/// and combine the compare with the branch instruction. Currently this is
6200/// applied for targets which have "cheap" jump instructions.
6201///
6202/// FIXME: Remove the (equivalent?) implementation in SelectionDAG.
6203///
6204bool CodeGenPrepare::splitBranchCondition(Function &F) {
6205 if (!TM || !TM->Options.EnableFastISel || !TLI || TLI->isJumpExpensive())
6206 return false;
6207
6208 bool MadeChange = false;
6209 for (auto &BB : F) {
6210 // Does this BB end with the following?
6211 // %cond1 = icmp|fcmp|binary instruction ...
6212 // %cond2 = icmp|fcmp|binary instruction ...
6213 // %cond.or = or|and i1 %cond1, cond2
6214 // br i1 %cond.or label %dest1, label %dest2"
6215 BinaryOperator *LogicOp;
6216 BasicBlock *TBB, *FBB;
6217 if (!match(BB.getTerminator(), m_Br(m_OneUse(m_BinOp(LogicOp)), TBB, FBB)))
6218 continue;
6219
6220 auto *Br1 = cast<BranchInst>(BB.getTerminator());
6221 if (Br1->getMetadata(LLVMContext::MD_unpredictable))
6222 continue;
6223
6224 unsigned Opc;
6225 Value *Cond1, *Cond2;
6226 if (match(LogicOp, m_And(m_OneUse(m_Value(Cond1)),
6227 m_OneUse(m_Value(Cond2)))))
6228 Opc = Instruction::And;
6229 else if (match(LogicOp, m_Or(m_OneUse(m_Value(Cond1)),
6230 m_OneUse(m_Value(Cond2)))))
6231 Opc = Instruction::Or;
6232 else
6233 continue;
6234
6235 if (!match(Cond1, m_CombineOr(m_Cmp(), m_BinOp())) ||
6236 !match(Cond2, m_CombineOr(m_Cmp(), m_BinOp())) )
6237 continue;
6238
6239 DEBUG(dbgs() << "Before branch condition splitting\n"; BB.dump())do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Before branch condition splitting\n"
; BB.dump(); } } while (false)
;
6240
6241 // Create a new BB.
6242 auto TmpBB =
6243 BasicBlock::Create(BB.getContext(), BB.getName() + ".cond.split",
6244 BB.getParent(), BB.getNextNode());
6245
6246 // Update original basic block by using the first condition directly by the
6247 // branch instruction and removing the no longer needed and/or instruction.
6248 Br1->setCondition(Cond1);
6249 LogicOp->eraseFromParent();
6250
6251 // Depending on the conditon we have to either replace the true or the false
6252 // successor of the original branch instruction.
6253 if (Opc == Instruction::And)
6254 Br1->setSuccessor(0, TmpBB);
6255 else
6256 Br1->setSuccessor(1, TmpBB);
6257
6258 // Fill in the new basic block.
6259 auto *Br2 = IRBuilder<>(TmpBB).CreateCondBr(Cond2, TBB, FBB);
6260 if (auto *I = dyn_cast<Instruction>(Cond2)) {
6261 I->removeFromParent();
6262 I->insertBefore(Br2);
6263 }
6264
6265 // Update PHI nodes in both successors. The original BB needs to be
6266 // replaced in one succesor's PHI nodes, because the branch comes now from
6267 // the newly generated BB (NewBB). In the other successor we need to add one
6268 // incoming edge to the PHI nodes, because both branch instructions target
6269 // now the same successor. Depending on the original branch condition
6270 // (and/or) we have to swap the successors (TrueDest, FalseDest), so that
6271 // we perform the correct update for the PHI nodes.
6272 // This doesn't change the successor order of the just created branch
6273 // instruction (or any other instruction).
6274 if (Opc == Instruction::Or)
6275 std::swap(TBB, FBB);
6276
6277 // Replace the old BB with the new BB.
6278 for (auto &I : *TBB) {
6279 PHINode *PN = dyn_cast<PHINode>(&I);
6280 if (!PN)
6281 break;
6282 int i;
6283 while ((i = PN->getBasicBlockIndex(&BB)) >= 0)
6284 PN->setIncomingBlock(i, TmpBB);
6285 }
6286
6287 // Add another incoming edge form the new BB.
6288 for (auto &I : *FBB) {
6289 PHINode *PN = dyn_cast<PHINode>(&I);
6290 if (!PN)
6291 break;
6292 auto *Val = PN->getIncomingValueForBlock(&BB);
6293 PN->addIncoming(Val, TmpBB);
6294 }
6295
6296 // Update the branch weights (from SelectionDAGBuilder::
6297 // FindMergedConditions).
6298 if (Opc == Instruction::Or) {
6299 // Codegen X | Y as:
6300 // BB1:
6301 // jmp_if_X TBB
6302 // jmp TmpBB
6303 // TmpBB:
6304 // jmp_if_Y TBB
6305 // jmp FBB
6306 //
6307
6308 // We have flexibility in setting Prob for BB1 and Prob for NewBB.
6309 // The requirement is that
6310 // TrueProb for BB1 + (FalseProb for BB1 * TrueProb for TmpBB)
6311 // = TrueProb for orignal BB.
6312 // Assuming the orignal weights are A and B, one choice is to set BB1's
6313 // weights to A and A+2B, and set TmpBB's weights to A and 2B. This choice
6314 // assumes that
6315 // TrueProb for BB1 == FalseProb for BB1 * TrueProb for TmpBB.
6316 // Another choice is to assume TrueProb for BB1 equals to TrueProb for
6317 // TmpBB, but the math is more complicated.
6318 uint64_t TrueWeight, FalseWeight;
6319 if (Br1->extractProfMetadata(TrueWeight, FalseWeight)) {
6320 uint64_t NewTrueWeight = TrueWeight;
6321 uint64_t NewFalseWeight = TrueWeight + 2 * FalseWeight;
6322 scaleWeights(NewTrueWeight, NewFalseWeight);
6323 Br1->setMetadata(LLVMContext::MD_prof, MDBuilder(Br1->getContext())
6324 .createBranchWeights(TrueWeight, FalseWeight));
6325
6326 NewTrueWeight = TrueWeight;
6327 NewFalseWeight = 2 * FalseWeight;
6328 scaleWeights(NewTrueWeight, NewFalseWeight);
6329 Br2->setMetadata(LLVMContext::MD_prof, MDBuilder(Br2->getContext())
6330 .createBranchWeights(TrueWeight, FalseWeight));
6331 }
6332 } else {
6333 // Codegen X & Y as:
6334 // BB1:
6335 // jmp_if_X TmpBB
6336 // jmp FBB
6337 // TmpBB:
6338 // jmp_if_Y TBB
6339 // jmp FBB
6340 //
6341 // This requires creation of TmpBB after CurBB.
6342
6343 // We have flexibility in setting Prob for BB1 and Prob for TmpBB.
6344 // The requirement is that
6345 // FalseProb for BB1 + (TrueProb for BB1 * FalseProb for TmpBB)
6346 // = FalseProb for orignal BB.
6347 // Assuming the orignal weights are A and B, one choice is to set BB1's
6348 // weights to 2A+B and B, and set TmpBB's weights to 2A and B. This choice
6349 // assumes that
6350 // FalseProb for BB1 == TrueProb for BB1 * FalseProb for TmpBB.
6351 uint64_t TrueWeight, FalseWeight;
6352 if (Br1->extractProfMetadata(TrueWeight, FalseWeight)) {
6353 uint64_t NewTrueWeight = 2 * TrueWeight + FalseWeight;
6354 uint64_t NewFalseWeight = FalseWeight;
6355 scaleWeights(NewTrueWeight, NewFalseWeight);
6356 Br1->setMetadata(LLVMContext::MD_prof, MDBuilder(Br1->getContext())
6357 .createBranchWeights(TrueWeight, FalseWeight));
6358
6359 NewTrueWeight = 2 * TrueWeight;
6360 NewFalseWeight = FalseWeight;
6361 scaleWeights(NewTrueWeight, NewFalseWeight);
6362 Br2->setMetadata(LLVMContext::MD_prof, MDBuilder(Br2->getContext())
6363 .createBranchWeights(TrueWeight, FalseWeight));
6364 }
6365 }
6366
6367 // Note: No point in getting fancy here, since the DT info is never
6368 // available to CodeGenPrepare.
6369 ModifiedDT = true;
6370
6371 MadeChange = true;
6372
6373 DEBUG(dbgs() << "After branch condition splitting\n"; BB.dump();do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "After branch condition splitting\n"
; BB.dump(); TmpBB->dump(); } } while (false)
6374 TmpBB->dump())do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "After branch condition splitting\n"
; BB.dump(); TmpBB->dump(); } } while (false)
;
6375 }
6376 return MadeChange;
6377}