Bug Summary

File:lib/CodeGen/CodeGenPrepare.cpp
Warning:line 1961, column 60
Called C++ object pointer is uninitialized

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/ADT/APInt.h"
17#include "llvm/ADT/ArrayRef.h"
18#include "llvm/ADT/DenseMap.h"
19#include "llvm/ADT/PointerIntPair.h"
20#include "llvm/ADT/STLExtras.h"
21#include "llvm/ADT/SetVector.h"
22#include "llvm/ADT/SmallPtrSet.h"
23#include "llvm/ADT/SmallVector.h"
24#include "llvm/ADT/Statistic.h"
25#include "llvm/Analysis/BlockFrequencyInfo.h"
26#include "llvm/Analysis/BranchProbabilityInfo.h"
27#include "llvm/Analysis/ConstantFolding.h"
28#include "llvm/Analysis/InstructionSimplify.h"
29#include "llvm/Analysis/LoopInfo.h"
30#include "llvm/Analysis/MemoryBuiltins.h"
31#include "llvm/Analysis/ProfileSummaryInfo.h"
32#include "llvm/Analysis/TargetLibraryInfo.h"
33#include "llvm/Analysis/TargetTransformInfo.h"
34#include "llvm/Analysis/ValueTracking.h"
35#include "llvm/CodeGen/Analysis.h"
36#include "llvm/CodeGen/ISDOpcodes.h"
37#include "llvm/CodeGen/MachineValueType.h"
38#include "llvm/CodeGen/SelectionDAGNodes.h"
39#include "llvm/CodeGen/TargetPassConfig.h"
40#include "llvm/CodeGen/ValueTypes.h"
41#include "llvm/IR/Argument.h"
42#include "llvm/IR/Attributes.h"
43#include "llvm/IR/BasicBlock.h"
44#include "llvm/IR/CallSite.h"
45#include "llvm/IR/Constant.h"
46#include "llvm/IR/Constants.h"
47#include "llvm/IR/DataLayout.h"
48#include "llvm/IR/DerivedTypes.h"
49#include "llvm/IR/Dominators.h"
50#include "llvm/IR/Function.h"
51#include "llvm/IR/GetElementPtrTypeIterator.h"
52#include "llvm/IR/GlobalValue.h"
53#include "llvm/IR/GlobalVariable.h"
54#include "llvm/IR/IRBuilder.h"
55#include "llvm/IR/InlineAsm.h"
56#include "llvm/IR/InstrTypes.h"
57#include "llvm/IR/Instruction.h"
58#include "llvm/IR/Instructions.h"
59#include "llvm/IR/IntrinsicInst.h"
60#include "llvm/IR/Intrinsics.h"
61#include "llvm/IR/LLVMContext.h"
62#include "llvm/IR/MDBuilder.h"
63#include "llvm/IR/Module.h"
64#include "llvm/IR/Operator.h"
65#include "llvm/IR/PatternMatch.h"
66#include "llvm/IR/Statepoint.h"
67#include "llvm/IR/Type.h"
68#include "llvm/IR/Use.h"
69#include "llvm/IR/User.h"
70#include "llvm/IR/Value.h"
71#include "llvm/IR/ValueHandle.h"
72#include "llvm/IR/ValueMap.h"
73#include "llvm/Pass.h"
74#include "llvm/Support/BlockFrequency.h"
75#include "llvm/Support/BranchProbability.h"
76#include "llvm/Support/Casting.h"
77#include "llvm/Support/CommandLine.h"
78#include "llvm/Support/Compiler.h"
79#include "llvm/Support/Debug.h"
80#include "llvm/Support/ErrorHandling.h"
81#include "llvm/Support/MathExtras.h"
82#include "llvm/Support/raw_ostream.h"
83#include "llvm/Target/TargetLowering.h"
84#include "llvm/Target/TargetMachine.h"
85#include "llvm/Target/TargetOptions.h"
86#include "llvm/Target/TargetSubtargetInfo.h"
87#include "llvm/Transforms/Utils/BasicBlockUtils.h"
88#include "llvm/Transforms/Utils/BypassSlowDivision.h"
89#include "llvm/Transforms/Utils/Cloning.h"
90#include "llvm/Transforms/Utils/Local.h"
91#include "llvm/Transforms/Utils/SimplifyLibCalls.h"
92#include "llvm/Transforms/Utils/ValueMapper.h"
93#include <algorithm>
94#include <cassert>
95#include <cstdint>
96#include <iterator>
97#include <limits>
98#include <memory>
99#include <utility>
100#include <vector>
101
102using namespace llvm;
103using namespace llvm::PatternMatch;
104
105#define DEBUG_TYPE"codegenprepare" "codegenprepare"
106
107STATISTIC(NumBlocksElim, "Number of blocks eliminated")static llvm::Statistic NumBlocksElim = {"codegenprepare", "NumBlocksElim"
, "Number of blocks eliminated", {0}, false}
;
108STATISTIC(NumPHIsElim, "Number of trivial PHIs eliminated")static llvm::Statistic NumPHIsElim = {"codegenprepare", "NumPHIsElim"
, "Number of trivial PHIs eliminated", {0}, false}
;
109STATISTIC(NumGEPsElim, "Number of GEPs converted to casts")static llvm::Statistic NumGEPsElim = {"codegenprepare", "NumGEPsElim"
, "Number of GEPs converted to casts", {0}, false}
;
110STATISTIC(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}
111 "sunken Cmps")static llvm::Statistic NumCmpUses = {"codegenprepare", "NumCmpUses"
, "Number of uses of Cmp expressions replaced with uses of " "sunken Cmps"
, {0}, false}
;
112STATISTIC(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}
113 "of sunken Casts")static llvm::Statistic NumCastUses = {"codegenprepare", "NumCastUses"
, "Number of uses of Cast expressions replaced with uses " "of sunken Casts"
, {0}, false}
;
114STATISTIC(NumMemoryInsts, "Number of memory instructions whose address "static llvm::Statistic NumMemoryInsts = {"codegenprepare", "NumMemoryInsts"
, "Number of memory instructions whose address " "computations were sunk"
, {0}, false}
115 "computations were sunk")static llvm::Statistic NumMemoryInsts = {"codegenprepare", "NumMemoryInsts"
, "Number of memory instructions whose address " "computations were sunk"
, {0}, false}
;
116STATISTIC(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}
;
117STATISTIC(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
}
;
118STATISTIC(NumAndsAdded,static llvm::Statistic NumAndsAdded = {"codegenprepare", "NumAndsAdded"
, "Number of and mask instructions added to form ext loads", {
0}, false}
119 "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}
;
120STATISTIC(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
}
;
121STATISTIC(NumRetsDup, "Number of return instructions duplicated")static llvm::Statistic NumRetsDup = {"codegenprepare", "NumRetsDup"
, "Number of return instructions duplicated", {0}, false}
;
122STATISTIC(NumDbgValueMoved, "Number of debug value instructions moved")static llvm::Statistic NumDbgValueMoved = {"codegenprepare", "NumDbgValueMoved"
, "Number of debug value instructions moved", {0}, false}
;
123STATISTIC(NumSelectsExpanded, "Number of selects turned into branches")static llvm::Statistic NumSelectsExpanded = {"codegenprepare"
, "NumSelectsExpanded", "Number of selects turned into branches"
, {0}, false}
;
124STATISTIC(NumStoreExtractExposed, "Number of store(extractelement) exposed")static llvm::Statistic NumStoreExtractExposed = {"codegenprepare"
, "NumStoreExtractExposed", "Number of store(extractelement) exposed"
, {0}, false}
;
125
126STATISTIC(NumMemCmpCalls, "Number of memcmp calls")static llvm::Statistic NumMemCmpCalls = {"codegenprepare", "NumMemCmpCalls"
, "Number of memcmp calls", {0}, false}
;
127STATISTIC(NumMemCmpNotConstant, "Number of memcmp calls without constant size")static llvm::Statistic NumMemCmpNotConstant = {"codegenprepare"
, "NumMemCmpNotConstant", "Number of memcmp calls without constant size"
, {0}, false}
;
128STATISTIC(NumMemCmpGreaterThanMax,static llvm::Statistic NumMemCmpGreaterThanMax = {"codegenprepare"
, "NumMemCmpGreaterThanMax", "Number of memcmp calls with size greater than max size"
, {0}, false}
129 "Number of memcmp calls with size greater than max size")static llvm::Statistic NumMemCmpGreaterThanMax = {"codegenprepare"
, "NumMemCmpGreaterThanMax", "Number of memcmp calls with size greater than max size"
, {0}, false}
;
130STATISTIC(NumMemCmpInlined, "Number of inlined memcmp calls")static llvm::Statistic NumMemCmpInlined = {"codegenprepare", "NumMemCmpInlined"
, "Number of inlined memcmp calls", {0}, false}
;
131
132static cl::opt<bool> DisableBranchOpts(
133 "disable-cgp-branch-opts", cl::Hidden, cl::init(false),
134 cl::desc("Disable branch optimizations in CodeGenPrepare"));
135
136static cl::opt<bool>
137 DisableGCOpts("disable-cgp-gc-opts", cl::Hidden, cl::init(false),
138 cl::desc("Disable GC optimizations in CodeGenPrepare"));
139
140static cl::opt<bool> DisableSelectToBranch(
141 "disable-cgp-select2branch", cl::Hidden, cl::init(false),
142 cl::desc("Disable select to branch conversion."));
143
144static cl::opt<bool> AddrSinkUsingGEPs(
145 "addr-sink-using-gep", cl::Hidden, cl::init(true),
146 cl::desc("Address sinking in CGP using GEPs."));
147
148static cl::opt<bool> EnableAndCmpSinking(
149 "enable-andcmp-sinking", cl::Hidden, cl::init(true),
150 cl::desc("Enable sinkinig and/cmp into branches."));
151
152static cl::opt<bool> DisableStoreExtract(
153 "disable-cgp-store-extract", cl::Hidden, cl::init(false),
154 cl::desc("Disable store(extract) optimizations in CodeGenPrepare"));
155
156static cl::opt<bool> StressStoreExtract(
157 "stress-cgp-store-extract", cl::Hidden, cl::init(false),
158 cl::desc("Stress test store(extract) optimizations in CodeGenPrepare"));
159
160static cl::opt<bool> DisableExtLdPromotion(
161 "disable-cgp-ext-ld-promotion", cl::Hidden, cl::init(false),
162 cl::desc("Disable ext(promotable(ld)) -> promoted(ext(ld)) optimization in "
163 "CodeGenPrepare"));
164
165static cl::opt<bool> StressExtLdPromotion(
166 "stress-cgp-ext-ld-promotion", cl::Hidden, cl::init(false),
167 cl::desc("Stress test ext(promotable(ld)) -> promoted(ext(ld)) "
168 "optimization in CodeGenPrepare"));
169
170static cl::opt<bool> DisablePreheaderProtect(
171 "disable-preheader-prot", cl::Hidden, cl::init(false),
172 cl::desc("Disable protection against removing loop preheaders"));
173
174static cl::opt<bool> ProfileGuidedSectionPrefix(
175 "profile-guided-section-prefix", cl::Hidden, cl::init(true), cl::ZeroOrMore,
176 cl::desc("Use profile info to add section prefix for hot/cold functions"));
177
178static cl::opt<unsigned> FreqRatioToSkipMerge(
179 "cgp-freq-ratio-to-skip-merge", cl::Hidden, cl::init(2),
180 cl::desc("Skip merging empty blocks if (frequency of empty block) / "
181 "(frequency of destination block) is greater than this ratio"));
182
183static cl::opt<bool> ForceSplitStore(
184 "force-split-store", cl::Hidden, cl::init(false),
185 cl::desc("Force store splitting no matter what the target query says."));
186
187static cl::opt<bool>
188EnableTypePromotionMerge("cgp-type-promotion-merge", cl::Hidden,
189 cl::desc("Enable merging of redundant sexts when one is dominating"
190 " the other."), cl::init(true));
191
192static cl::opt<unsigned> MemCmpNumLoadsPerBlock(
193 "memcmp-num-loads-per-block", cl::Hidden, cl::init(1),
194 cl::desc("The number of loads per basic block for inline expansion of "
195 "memcmp that is only being compared against zero."));
196
197namespace {
198
199using SetOfInstrs = SmallPtrSet<Instruction *, 16>;
200using TypeIsSExt = PointerIntPair<Type *, 1, bool>;
201using InstrToOrigTy = DenseMap<Instruction *, TypeIsSExt>;
202using SExts = SmallVector<Instruction *, 16>;
203using ValueToSExts = DenseMap<Value *, SExts>;
204
205class TypePromotionTransaction;
206
207 class CodeGenPrepare : public FunctionPass {
208 const TargetMachine *TM = nullptr;
209 const TargetSubtargetInfo *SubtargetInfo;
210 const TargetLowering *TLI = nullptr;
211 const TargetRegisterInfo *TRI;
212 const TargetTransformInfo *TTI = nullptr;
213 const TargetLibraryInfo *TLInfo;
214 const LoopInfo *LI;
215 std::unique_ptr<BlockFrequencyInfo> BFI;
216 std::unique_ptr<BranchProbabilityInfo> BPI;
217
218 /// As we scan instructions optimizing them, this is the next instruction
219 /// to optimize. Transforms that can invalidate this should update it.
220 BasicBlock::iterator CurInstIterator;
221
222 /// Keeps track of non-local addresses that have been sunk into a block.
223 /// This allows us to avoid inserting duplicate code for blocks with
224 /// multiple load/stores of the same address.
225 ValueMap<Value*, Value*> SunkAddrs;
226
227 /// Keeps track of all instructions inserted for the current function.
228 SetOfInstrs InsertedInsts;
229
230 /// Keeps track of the type of the related instruction before their
231 /// promotion for the current function.
232 InstrToOrigTy PromotedInsts;
233
234 /// Keep track of instructions removed during promotion.
235 SetOfInstrs RemovedInsts;
236
237 /// Keep track of sext chains based on their initial value.
238 DenseMap<Value *, Instruction *> SeenChainsForSExt;
239
240 /// Keep track of SExt promoted.
241 ValueToSExts ValToSExtendedUses;
242
243 /// True if CFG is modified in any way.
244 bool ModifiedDT;
245
246 /// True if optimizing for size.
247 bool OptSize;
248
249 /// DataLayout for the Function being processed.
250 const DataLayout *DL = nullptr;
251
252 public:
253 static char ID; // Pass identification, replacement for typeid
254
255 CodeGenPrepare() : FunctionPass(ID) {
256 initializeCodeGenPreparePass(*PassRegistry::getPassRegistry());
257 }
258
259 bool runOnFunction(Function &F) override;
260
261 StringRef getPassName() const override { return "CodeGen Prepare"; }
262
263 void getAnalysisUsage(AnalysisUsage &AU) const override {
264 // FIXME: When we can selectively preserve passes, preserve the domtree.
265 AU.addRequired<ProfileSummaryInfoWrapperPass>();
266 AU.addRequired<TargetLibraryInfoWrapperPass>();
267 AU.addRequired<TargetTransformInfoWrapperPass>();
268 AU.addRequired<LoopInfoWrapperPass>();
269 }
270
271 private:
272 bool eliminateFallThrough(Function &F);
273 bool eliminateMostlyEmptyBlocks(Function &F);
274 BasicBlock *findDestBlockOfMergeableEmptyBlock(BasicBlock *BB);
275 bool canMergeBlocks(const BasicBlock *BB, const BasicBlock *DestBB) const;
276 void eliminateMostlyEmptyBlock(BasicBlock *BB);
277 bool isMergingEmptyBlockProfitable(BasicBlock *BB, BasicBlock *DestBB,
278 bool isPreheader);
279 bool optimizeBlock(BasicBlock &BB, bool &ModifiedDT);
280 bool optimizeInst(Instruction *I, bool &ModifiedDT);
281 bool optimizeMemoryInst(Instruction *I, Value *Addr,
282 Type *AccessTy, unsigned AS);
283 bool optimizeInlineAsmInst(CallInst *CS);
284 bool optimizeCallInst(CallInst *CI, bool &ModifiedDT);
285 bool optimizeExt(Instruction *&I);
286 bool optimizeExtUses(Instruction *I);
287 bool optimizeLoadExt(LoadInst *I);
288 bool optimizeSelectInst(SelectInst *SI);
289 bool optimizeShuffleVectorInst(ShuffleVectorInst *SI);
290 bool optimizeSwitchInst(SwitchInst *CI);
291 bool optimizeExtractElementInst(Instruction *Inst);
292 bool dupRetToEnableTailCallOpts(BasicBlock *BB);
293 bool placeDbgValues(Function &F);
294 bool canFormExtLd(const SmallVectorImpl<Instruction *> &MovedExts,
295 LoadInst *&LI, Instruction *&Inst, bool HasPromoted);
296 bool tryToPromoteExts(TypePromotionTransaction &TPT,
297 const SmallVectorImpl<Instruction *> &Exts,
298 SmallVectorImpl<Instruction *> &ProfitablyMovedExts,
299 unsigned CreatedInstsCost = 0);
300 bool mergeSExts(Function &F);
301 bool performAddressTypePromotion(
302 Instruction *&Inst,
303 bool AllowPromotionWithoutCommonHeader,
304 bool HasPromoted, TypePromotionTransaction &TPT,
305 SmallVectorImpl<Instruction *> &SpeculativelyMovedExts);
306 bool splitBranchCondition(Function &F);
307 bool simplifyOffsetableRelocate(Instruction &I);
308 bool splitIndirectCriticalEdges(Function &F);
309 };
310
311} // end anonymous namespace
312
313char CodeGenPrepare::ID = 0;
314
315INITIALIZE_PASS_BEGIN(CodeGenPrepare, DEBUG_TYPE,static void *initializeCodeGenPreparePassOnce(PassRegistry &
Registry) {
316 "Optimize for code generation", false, false)static void *initializeCodeGenPreparePassOnce(PassRegistry &
Registry) {
317INITIALIZE_PASS_DEPENDENCY(ProfileSummaryInfoWrapperPass)initializeProfileSummaryInfoWrapperPassPass(Registry);
318INITIALIZE_PASS_END(CodeGenPrepare, DEBUG_TYPE,PassInfo *PI = new PassInfo( "Optimize for code generation", "codegenprepare"
, &CodeGenPrepare::ID, PassInfo::NormalCtor_t(callDefaultCtor
<CodeGenPrepare>), false, false); Registry.registerPass
(*PI, true); return PI; } static llvm::once_flag InitializeCodeGenPreparePassFlag
; void llvm::initializeCodeGenPreparePass(PassRegistry &Registry
) { llvm::call_once(InitializeCodeGenPreparePassFlag, initializeCodeGenPreparePassOnce
, std::ref(Registry)); }
319 "Optimize for code generation", false, false)PassInfo *PI = new PassInfo( "Optimize for code generation", "codegenprepare"
, &CodeGenPrepare::ID, PassInfo::NormalCtor_t(callDefaultCtor
<CodeGenPrepare>), false, false); Registry.registerPass
(*PI, true); return PI; } static llvm::once_flag InitializeCodeGenPreparePassFlag
; void llvm::initializeCodeGenPreparePass(PassRegistry &Registry
) { llvm::call_once(InitializeCodeGenPreparePassFlag, initializeCodeGenPreparePassOnce
, std::ref(Registry)); }
320
321FunctionPass *llvm::createCodeGenPreparePass() { return new CodeGenPrepare(); }
322
323bool CodeGenPrepare::runOnFunction(Function &F) {
324 if (skipFunction(F))
325 return false;
326
327 DL = &F.getParent()->getDataLayout();
328
329 bool EverMadeChange = false;
330 // Clear per function information.
331 InsertedInsts.clear();
332 PromotedInsts.clear();
333 BFI.reset();
334 BPI.reset();
335
336 ModifiedDT = false;
337 if (auto *TPC = getAnalysisIfAvailable<TargetPassConfig>()) {
338 TM = &TPC->getTM<TargetMachine>();
339 SubtargetInfo = TM->getSubtargetImpl(F);
340 TLI = SubtargetInfo->getTargetLowering();
341 TRI = SubtargetInfo->getRegisterInfo();
342 }
343 TLInfo = &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
344 TTI = &getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
345 LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
346 OptSize = F.optForSize();
347
348 if (ProfileGuidedSectionPrefix) {
349 ProfileSummaryInfo *PSI =
350 getAnalysis<ProfileSummaryInfoWrapperPass>().getPSI();
351 if (PSI->isFunctionHotInCallGraph(&F))
352 F.setSectionPrefix(".hot");
353 else if (PSI->isFunctionColdInCallGraph(&F))
354 F.setSectionPrefix(".unlikely");
355 }
356
357 /// This optimization identifies DIV instructions that can be
358 /// profitably bypassed and carried out with a shorter, faster divide.
359 if (!OptSize && TLI && TLI->isSlowDivBypassed()) {
360 const DenseMap<unsigned int, unsigned int> &BypassWidths =
361 TLI->getBypassSlowDivWidths();
362 BasicBlock* BB = &*F.begin();
363 while (BB != nullptr) {
364 // bypassSlowDivision may create new BBs, but we don't want to reapply the
365 // optimization to those blocks.
366 BasicBlock* Next = BB->getNextNode();
367 EverMadeChange |= bypassSlowDivision(BB, BypassWidths);
368 BB = Next;
369 }
370 }
371
372 // Eliminate blocks that contain only PHI nodes and an
373 // unconditional branch.
374 EverMadeChange |= eliminateMostlyEmptyBlocks(F);
375
376 // llvm.dbg.value is far away from the value then iSel may not be able
377 // handle it properly. iSel will drop llvm.dbg.value if it can not
378 // find a node corresponding to the value.
379 EverMadeChange |= placeDbgValues(F);
380
381 if (!DisableBranchOpts)
382 EverMadeChange |= splitBranchCondition(F);
383
384 // Split some critical edges where one of the sources is an indirect branch,
385 // to help generate sane code for PHIs involving such edges.
386 EverMadeChange |= splitIndirectCriticalEdges(F);
387
388 bool MadeChange = true;
389 while (MadeChange) {
390 MadeChange = false;
391 SeenChainsForSExt.clear();
392 ValToSExtendedUses.clear();
393 RemovedInsts.clear();
394 for (Function::iterator I = F.begin(); I != F.end(); ) {
395 BasicBlock *BB = &*I++;
396 bool ModifiedDTOnIteration = false;
397 MadeChange |= optimizeBlock(*BB, ModifiedDTOnIteration);
398
399 // Restart BB iteration if the dominator tree of the Function was changed
400 if (ModifiedDTOnIteration)
401 break;
402 }
403 if (EnableTypePromotionMerge && !ValToSExtendedUses.empty())
404 MadeChange |= mergeSExts(F);
405
406 // Really free removed instructions during promotion.
407 for (Instruction *I : RemovedInsts)
408 I->deleteValue();
409
410 EverMadeChange |= MadeChange;
411 }
412
413 SunkAddrs.clear();
414
415 if (!DisableBranchOpts) {
416 MadeChange = false;
417 SmallPtrSet<BasicBlock*, 8> WorkList;
418 for (BasicBlock &BB : F) {
419 SmallVector<BasicBlock *, 2> Successors(succ_begin(&BB), succ_end(&BB));
420 MadeChange |= ConstantFoldTerminator(&BB, true);
421 if (!MadeChange) continue;
422
423 for (SmallVectorImpl<BasicBlock*>::iterator
424 II = Successors.begin(), IE = Successors.end(); II != IE; ++II)
425 if (pred_begin(*II) == pred_end(*II))
426 WorkList.insert(*II);
427 }
428
429 // Delete the dead blocks and any of their dead successors.
430 MadeChange |= !WorkList.empty();
431 while (!WorkList.empty()) {
432 BasicBlock *BB = *WorkList.begin();
433 WorkList.erase(BB);
434 SmallVector<BasicBlock*, 2> Successors(succ_begin(BB), succ_end(BB));
435
436 DeleteDeadBlock(BB);
437
438 for (SmallVectorImpl<BasicBlock*>::iterator
439 II = Successors.begin(), IE = Successors.end(); II != IE; ++II)
440 if (pred_begin(*II) == pred_end(*II))
441 WorkList.insert(*II);
442 }
443
444 // Merge pairs of basic blocks with unconditional branches, connected by
445 // a single edge.
446 if (EverMadeChange || MadeChange)
447 MadeChange |= eliminateFallThrough(F);
448
449 EverMadeChange |= MadeChange;
450 }
451
452 if (!DisableGCOpts) {
453 SmallVector<Instruction *, 2> Statepoints;
454 for (BasicBlock &BB : F)
455 for (Instruction &I : BB)
456 if (isStatepoint(I))
457 Statepoints.push_back(&I);
458 for (auto &I : Statepoints)
459 EverMadeChange |= simplifyOffsetableRelocate(*I);
460 }
461
462 return EverMadeChange;
463}
464
465/// Merge basic blocks which are connected by a single edge, where one of the
466/// basic blocks has a single successor pointing to the other basic block,
467/// which has a single predecessor.
468bool CodeGenPrepare::eliminateFallThrough(Function &F) {
469 bool Changed = false;
470 // Scan all of the blocks in the function, except for the entry block.
471 for (Function::iterator I = std::next(F.begin()), E = F.end(); I != E;) {
472 BasicBlock *BB = &*I++;
473 // If the destination block has a single pred, then this is a trivial
474 // edge, just collapse it.
475 BasicBlock *SinglePred = BB->getSinglePredecessor();
476
477 // Don't merge if BB's address is taken.
478 if (!SinglePred || SinglePred == BB || BB->hasAddressTaken()) continue;
479
480 BranchInst *Term = dyn_cast<BranchInst>(SinglePred->getTerminator());
481 if (Term && !Term->isConditional()) {
482 Changed = true;
483 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)
;
484 // Remember if SinglePred was the entry block of the function.
485 // If so, we will need to move BB back to the entry position.
486 bool isEntry = SinglePred == &SinglePred->getParent()->getEntryBlock();
487 MergeBasicBlockIntoOnlyPred(BB, nullptr);
488
489 if (isEntry && BB != &BB->getParent()->getEntryBlock())
490 BB->moveBefore(&BB->getParent()->getEntryBlock());
491
492 // We have erased a block. Update the iterator.
493 I = BB->getIterator();
494 }
495 }
496 return Changed;
497}
498
499/// Find a destination block from BB if BB is mergeable empty block.
500BasicBlock *CodeGenPrepare::findDestBlockOfMergeableEmptyBlock(BasicBlock *BB) {
501 // If this block doesn't end with an uncond branch, ignore it.
502 BranchInst *BI = dyn_cast<BranchInst>(BB->getTerminator());
503 if (!BI || !BI->isUnconditional())
504 return nullptr;
505
506 // If the instruction before the branch (skipping debug info) isn't a phi
507 // node, then other stuff is happening here.
508 BasicBlock::iterator BBI = BI->getIterator();
509 if (BBI != BB->begin()) {
510 --BBI;
511 while (isa<DbgInfoIntrinsic>(BBI)) {
512 if (BBI == BB->begin())
513 break;
514 --BBI;
515 }
516 if (!isa<DbgInfoIntrinsic>(BBI) && !isa<PHINode>(BBI))
517 return nullptr;
518 }
519
520 // Do not break infinite loops.
521 BasicBlock *DestBB = BI->getSuccessor(0);
522 if (DestBB == BB)
523 return nullptr;
524
525 if (!canMergeBlocks(BB, DestBB))
526 DestBB = nullptr;
527
528 return DestBB;
529}
530
531// Return the unique indirectbr predecessor of a block. This may return null
532// even if such a predecessor exists, if it's not useful for splitting.
533// If a predecessor is found, OtherPreds will contain all other (non-indirectbr)
534// predecessors of BB.
535static BasicBlock *
536findIBRPredecessor(BasicBlock *BB, SmallVectorImpl<BasicBlock *> &OtherPreds) {
537 // If the block doesn't have any PHIs, we don't care about it, since there's
538 // no point in splitting it.
539 PHINode *PN = dyn_cast<PHINode>(BB->begin());
540 if (!PN)
541 return nullptr;
542
543 // Verify we have exactly one IBR predecessor.
544 // Conservatively bail out if one of the other predecessors is not a "regular"
545 // terminator (that is, not a switch or a br).
546 BasicBlock *IBB = nullptr;
547 for (unsigned Pred = 0, E = PN->getNumIncomingValues(); Pred != E; ++Pred) {
548 BasicBlock *PredBB = PN->getIncomingBlock(Pred);
549 TerminatorInst *PredTerm = PredBB->getTerminator();
550 switch (PredTerm->getOpcode()) {
551 case Instruction::IndirectBr:
552 if (IBB)
553 return nullptr;
554 IBB = PredBB;
555 break;
556 case Instruction::Br:
557 case Instruction::Switch:
558 OtherPreds.push_back(PredBB);
559 continue;
560 default:
561 return nullptr;
562 }
563 }
564
565 return IBB;
566}
567
568// Split critical edges where the source of the edge is an indirectbr
569// instruction. This isn't always possible, but we can handle some easy cases.
570// This is useful because MI is unable to split such critical edges,
571// which means it will not be able to sink instructions along those edges.
572// This is especially painful for indirect branches with many successors, where
573// we end up having to prepare all outgoing values in the origin block.
574//
575// Our normal algorithm for splitting critical edges requires us to update
576// the outgoing edges of the edge origin block, but for an indirectbr this
577// is hard, since it would require finding and updating the block addresses
578// the indirect branch uses. But if a block only has a single indirectbr
579// predecessor, with the others being regular branches, we can do it in a
580// different way.
581// Say we have A -> D, B -> D, I -> D where only I -> D is an indirectbr.
582// We can split D into D0 and D1, where D0 contains only the PHIs from D,
583// and D1 is the D block body. We can then duplicate D0 as D0A and D0B, and
584// create the following structure:
585// A -> D0A, B -> D0A, I -> D0B, D0A -> D1, D0B -> D1
586bool CodeGenPrepare::splitIndirectCriticalEdges(Function &F) {
587 // Check whether the function has any indirectbrs, and collect which blocks
588 // they may jump to. Since most functions don't have indirect branches,
589 // this lowers the common case's overhead to O(Blocks) instead of O(Edges).
590 SmallSetVector<BasicBlock *, 16> Targets;
591 for (auto &BB : F) {
592 auto *IBI = dyn_cast<IndirectBrInst>(BB.getTerminator());
593 if (!IBI)
594 continue;
595
596 for (unsigned Succ = 0, E = IBI->getNumSuccessors(); Succ != E; ++Succ)
597 Targets.insert(IBI->getSuccessor(Succ));
598 }
599
600 if (Targets.empty())
601 return false;
602
603 bool Changed = false;
604 for (BasicBlock *Target : Targets) {
605 SmallVector<BasicBlock *, 16> OtherPreds;
606 BasicBlock *IBRPred = findIBRPredecessor(Target, OtherPreds);
607 // If we did not found an indirectbr, or the indirectbr is the only
608 // incoming edge, this isn't the kind of edge we're looking for.
609 if (!IBRPred || OtherPreds.empty())
610 continue;
611
612 // Don't even think about ehpads/landingpads.
613 Instruction *FirstNonPHI = Target->getFirstNonPHI();
614 if (FirstNonPHI->isEHPad() || Target->isLandingPad())
615 continue;
616
617 BasicBlock *BodyBlock = Target->splitBasicBlock(FirstNonPHI, ".split");
618 // It's possible Target was its own successor through an indirectbr.
619 // In this case, the indirectbr now comes from BodyBlock.
620 if (IBRPred == Target)
621 IBRPred = BodyBlock;
622
623 // At this point Target only has PHIs, and BodyBlock has the rest of the
624 // block's body. Create a copy of Target that will be used by the "direct"
625 // preds.
626 ValueToValueMapTy VMap;
627 BasicBlock *DirectSucc = CloneBasicBlock(Target, VMap, ".clone", &F);
628
629 for (BasicBlock *Pred : OtherPreds) {
630 // If the target is a loop to itself, then the terminator of the split
631 // block needs to be updated.
632 if (Pred == Target)
633 BodyBlock->getTerminator()->replaceUsesOfWith(Target, DirectSucc);
634 else
635 Pred->getTerminator()->replaceUsesOfWith(Target, DirectSucc);
636 }
637
638 // Ok, now fix up the PHIs. We know the two blocks only have PHIs, and that
639 // they are clones, so the number of PHIs are the same.
640 // (a) Remove the edge coming from IBRPred from the "Direct" PHI
641 // (b) Leave that as the only edge in the "Indirect" PHI.
642 // (c) Merge the two in the body block.
643 BasicBlock::iterator Indirect = Target->begin(),
644 End = Target->getFirstNonPHI()->getIterator();
645 BasicBlock::iterator Direct = DirectSucc->begin();
646 BasicBlock::iterator MergeInsert = BodyBlock->getFirstInsertionPt();
647
648 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\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 649, __PRETTY_FUNCTION__))
649 "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\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 649, __PRETTY_FUNCTION__))
;
650
651 while (Indirect != End) {
652 PHINode *DirPHI = cast<PHINode>(Direct);
653 PHINode *IndPHI = cast<PHINode>(Indirect);
654
655 // Now, clean up - the direct block shouldn't get the indirect value,
656 // and vice versa.
657 DirPHI->removeIncomingValue(IBRPred);
658 Direct++;
659
660 // Advance the pointer here, to avoid invalidation issues when the old
661 // PHI is erased.
662 Indirect++;
663
664 PHINode *NewIndPHI = PHINode::Create(IndPHI->getType(), 1, "ind", IndPHI);
665 NewIndPHI->addIncoming(IndPHI->getIncomingValueForBlock(IBRPred),
666 IBRPred);
667
668 // Create a PHI in the body block, to merge the direct and indirect
669 // predecessors.
670 PHINode *MergePHI =
671 PHINode::Create(IndPHI->getType(), 2, "merge", &*MergeInsert);
672 MergePHI->addIncoming(NewIndPHI, Target);
673 MergePHI->addIncoming(DirPHI, DirectSucc);
674
675 IndPHI->replaceAllUsesWith(MergePHI);
676 IndPHI->eraseFromParent();
677 }
678
679 Changed = true;
680 }
681
682 return Changed;
683}
684
685/// Eliminate blocks that contain only PHI nodes, debug info directives, and an
686/// unconditional branch. Passes before isel (e.g. LSR/loopsimplify) often split
687/// edges in ways that are non-optimal for isel. Start by eliminating these
688/// blocks so we can split them the way we want them.
689bool CodeGenPrepare::eliminateMostlyEmptyBlocks(Function &F) {
690 SmallPtrSet<BasicBlock *, 16> Preheaders;
691 SmallVector<Loop *, 16> LoopList(LI->begin(), LI->end());
692 while (!LoopList.empty()) {
693 Loop *L = LoopList.pop_back_val();
694 LoopList.insert(LoopList.end(), L->begin(), L->end());
695 if (BasicBlock *Preheader = L->getLoopPreheader())
696 Preheaders.insert(Preheader);
697 }
698
699 bool MadeChange = false;
700 // Note that this intentionally skips the entry block.
701 for (Function::iterator I = std::next(F.begin()), E = F.end(); I != E;) {
702 BasicBlock *BB = &*I++;
703 BasicBlock *DestBB = findDestBlockOfMergeableEmptyBlock(BB);
704 if (!DestBB ||
705 !isMergingEmptyBlockProfitable(BB, DestBB, Preheaders.count(BB)))
706 continue;
707
708 eliminateMostlyEmptyBlock(BB);
709 MadeChange = true;
710 }
711 return MadeChange;
712}
713
714bool CodeGenPrepare::isMergingEmptyBlockProfitable(BasicBlock *BB,
715 BasicBlock *DestBB,
716 bool isPreheader) {
717 // Do not delete loop preheaders if doing so would create a critical edge.
718 // Loop preheaders can be good locations to spill registers. If the
719 // preheader is deleted and we create a critical edge, registers may be
720 // spilled in the loop body instead.
721 if (!DisablePreheaderProtect && isPreheader &&
722 !(BB->getSinglePredecessor() &&
723 BB->getSinglePredecessor()->getSingleSuccessor()))
724 return false;
725
726 // Try to skip merging if the unique predecessor of BB is terminated by a
727 // switch or indirect branch instruction, and BB is used as an incoming block
728 // of PHIs in DestBB. In such case, merging BB and DestBB would cause ISel to
729 // add COPY instructions in the predecessor of BB instead of BB (if it is not
730 // merged). Note that the critical edge created by merging such blocks wont be
731 // split in MachineSink because the jump table is not analyzable. By keeping
732 // such empty block (BB), ISel will place COPY instructions in BB, not in the
733 // predecessor of BB.
734 BasicBlock *Pred = BB->getUniquePredecessor();
735 if (!Pred ||
736 !(isa<SwitchInst>(Pred->getTerminator()) ||
737 isa<IndirectBrInst>(Pred->getTerminator())))
738 return true;
739
740 if (BB->getTerminator() != BB->getFirstNonPHI())
741 return true;
742
743 // We use a simple cost heuristic which determine skipping merging is
744 // profitable if the cost of skipping merging is less than the cost of
745 // merging : Cost(skipping merging) < Cost(merging BB), where the
746 // Cost(skipping merging) is Freq(BB) * (Cost(Copy) + Cost(Branch)), and
747 // the Cost(merging BB) is Freq(Pred) * Cost(Copy).
748 // Assuming Cost(Copy) == Cost(Branch), we could simplify it to :
749 // Freq(Pred) / Freq(BB) > 2.
750 // Note that if there are multiple empty blocks sharing the same incoming
751 // value for the PHIs in the DestBB, we consider them together. In such
752 // case, Cost(merging BB) will be the sum of their frequencies.
753
754 if (!isa<PHINode>(DestBB->begin()))
755 return true;
756
757 SmallPtrSet<BasicBlock *, 16> SameIncomingValueBBs;
758
759 // Find all other incoming blocks from which incoming values of all PHIs in
760 // DestBB are the same as the ones from BB.
761 for (pred_iterator PI = pred_begin(DestBB), E = pred_end(DestBB); PI != E;
762 ++PI) {
763 BasicBlock *DestBBPred = *PI;
764 if (DestBBPred == BB)
765 continue;
766
767 bool HasAllSameValue = true;
768 BasicBlock::const_iterator DestBBI = DestBB->begin();
769 while (const PHINode *DestPN = dyn_cast<PHINode>(DestBBI++)) {
770 if (DestPN->getIncomingValueForBlock(BB) !=
771 DestPN->getIncomingValueForBlock(DestBBPred)) {
772 HasAllSameValue = false;
773 break;
774 }
775 }
776 if (HasAllSameValue)
777 SameIncomingValueBBs.insert(DestBBPred);
778 }
779
780 // See if all BB's incoming values are same as the value from Pred. In this
781 // case, no reason to skip merging because COPYs are expected to be place in
782 // Pred already.
783 if (SameIncomingValueBBs.count(Pred))
784 return true;
785
786 if (!BFI) {
787 Function &F = *BB->getParent();
788 LoopInfo LI{DominatorTree(F)};
789 BPI.reset(new BranchProbabilityInfo(F, LI));
790 BFI.reset(new BlockFrequencyInfo(F, *BPI, LI));
791 }
792
793 BlockFrequency PredFreq = BFI->getBlockFreq(Pred);
794 BlockFrequency BBFreq = BFI->getBlockFreq(BB);
795
796 for (auto SameValueBB : SameIncomingValueBBs)
797 if (SameValueBB->getUniquePredecessor() == Pred &&
798 DestBB == findDestBlockOfMergeableEmptyBlock(SameValueBB))
799 BBFreq += BFI->getBlockFreq(SameValueBB);
800
801 return PredFreq.getFrequency() <=
802 BBFreq.getFrequency() * FreqRatioToSkipMerge;
803}
804
805/// Return true if we can merge BB into DestBB if there is a single
806/// unconditional branch between them, and BB contains no other non-phi
807/// instructions.
808bool CodeGenPrepare::canMergeBlocks(const BasicBlock *BB,
809 const BasicBlock *DestBB) const {
810 // We only want to eliminate blocks whose phi nodes are used by phi nodes in
811 // the successor. If there are more complex condition (e.g. preheaders),
812 // don't mess around with them.
813 BasicBlock::const_iterator BBI = BB->begin();
814 while (const PHINode *PN = dyn_cast<PHINode>(BBI++)) {
815 for (const User *U : PN->users()) {
816 const Instruction *UI = cast<Instruction>(U);
817 if (UI->getParent() != DestBB || !isa<PHINode>(UI))
818 return false;
819 // If User is inside DestBB block and it is a PHINode then check
820 // incoming value. If incoming value is not from BB then this is
821 // a complex condition (e.g. preheaders) we want to avoid here.
822 if (UI->getParent() == DestBB) {
823 if (const PHINode *UPN = dyn_cast<PHINode>(UI))
824 for (unsigned I = 0, E = UPN->getNumIncomingValues(); I != E; ++I) {
825 Instruction *Insn = dyn_cast<Instruction>(UPN->getIncomingValue(I));
826 if (Insn && Insn->getParent() == BB &&
827 Insn->getParent() != UPN->getIncomingBlock(I))
828 return false;
829 }
830 }
831 }
832 }
833
834 // If BB and DestBB contain any common predecessors, then the phi nodes in BB
835 // and DestBB may have conflicting incoming values for the block. If so, we
836 // can't merge the block.
837 const PHINode *DestBBPN = dyn_cast<PHINode>(DestBB->begin());
838 if (!DestBBPN) return true; // no conflict.
839
840 // Collect the preds of BB.
841 SmallPtrSet<const BasicBlock*, 16> BBPreds;
842 if (const PHINode *BBPN = dyn_cast<PHINode>(BB->begin())) {
843 // It is faster to get preds from a PHI than with pred_iterator.
844 for (unsigned i = 0, e = BBPN->getNumIncomingValues(); i != e; ++i)
845 BBPreds.insert(BBPN->getIncomingBlock(i));
846 } else {
847 BBPreds.insert(pred_begin(BB), pred_end(BB));
848 }
849
850 // Walk the preds of DestBB.
851 for (unsigned i = 0, e = DestBBPN->getNumIncomingValues(); i != e; ++i) {
852 BasicBlock *Pred = DestBBPN->getIncomingBlock(i);
853 if (BBPreds.count(Pred)) { // Common predecessor?
854 BBI = DestBB->begin();
855 while (const PHINode *PN = dyn_cast<PHINode>(BBI++)) {
856 const Value *V1 = PN->getIncomingValueForBlock(Pred);
857 const Value *V2 = PN->getIncomingValueForBlock(BB);
858
859 // If V2 is a phi node in BB, look up what the mapped value will be.
860 if (const PHINode *V2PN = dyn_cast<PHINode>(V2))
861 if (V2PN->getParent() == BB)
862 V2 = V2PN->getIncomingValueForBlock(Pred);
863
864 // If there is a conflict, bail out.
865 if (V1 != V2) return false;
866 }
867 }
868 }
869
870 return true;
871}
872
873/// Eliminate a basic block that has only phi's and an unconditional branch in
874/// it.
875void CodeGenPrepare::eliminateMostlyEmptyBlock(BasicBlock *BB) {
876 BranchInst *BI = cast<BranchInst>(BB->getTerminator());
877 BasicBlock *DestBB = BI->getSuccessor(0);
878
879 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)
;
880
881 // If the destination block has a single pred, then this is a trivial edge,
882 // just collapse it.
883 if (BasicBlock *SinglePred = DestBB->getSinglePredecessor()) {
884 if (SinglePred != DestBB) {
885 // Remember if SinglePred was the entry block of the function. If so, we
886 // will need to move BB back to the entry position.
887 bool isEntry = SinglePred == &SinglePred->getParent()->getEntryBlock();
888 MergeBasicBlockIntoOnlyPred(DestBB, nullptr);
889
890 if (isEntry && BB != &BB->getParent()->getEntryBlock())
891 BB->moveBefore(&BB->getParent()->getEntryBlock());
892
893 DEBUG(dbgs() << "AFTER:\n" << *DestBB << "\n\n\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "AFTER:\n" << *DestBB
<< "\n\n\n"; } } while (false)
;
894 return;
895 }
896 }
897
898 // Otherwise, we have multiple predecessors of BB. Update the PHIs in DestBB
899 // to handle the new incoming edges it is about to have.
900 PHINode *PN;
901 for (BasicBlock::iterator BBI = DestBB->begin();
902 (PN = dyn_cast<PHINode>(BBI)); ++BBI) {
903 // Remove the incoming value for BB, and remember it.
904 Value *InVal = PN->removeIncomingValue(BB, false);
905
906 // Two options: either the InVal is a phi node defined in BB or it is some
907 // value that dominates BB.
908 PHINode *InValPhi = dyn_cast<PHINode>(InVal);
909 if (InValPhi && InValPhi->getParent() == BB) {
910 // Add all of the input values of the input PHI as inputs of this phi.
911 for (unsigned i = 0, e = InValPhi->getNumIncomingValues(); i != e; ++i)
912 PN->addIncoming(InValPhi->getIncomingValue(i),
913 InValPhi->getIncomingBlock(i));
914 } else {
915 // Otherwise, add one instance of the dominating value for each edge that
916 // we will be adding.
917 if (PHINode *BBPN = dyn_cast<PHINode>(BB->begin())) {
918 for (unsigned i = 0, e = BBPN->getNumIncomingValues(); i != e; ++i)
919 PN->addIncoming(InVal, BBPN->getIncomingBlock(i));
920 } else {
921 for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI)
922 PN->addIncoming(InVal, *PI);
923 }
924 }
925 }
926
927 // The PHIs are now updated, change everything that refers to BB to use
928 // DestBB and remove BB.
929 BB->replaceAllUsesWith(DestBB);
930 BB->eraseFromParent();
931 ++NumBlocksElim;
932
933 DEBUG(dbgs() << "AFTER:\n" << *DestBB << "\n\n\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "AFTER:\n" << *DestBB
<< "\n\n\n"; } } while (false)
;
934}
935
936// Computes a map of base pointer relocation instructions to corresponding
937// derived pointer relocation instructions given a vector of all relocate calls
938static void computeBaseDerivedRelocateMap(
939 const SmallVectorImpl<GCRelocateInst *> &AllRelocateCalls,
940 DenseMap<GCRelocateInst *, SmallVector<GCRelocateInst *, 2>>
941 &RelocateInstMap) {
942 // Collect information in two maps: one primarily for locating the base object
943 // while filling the second map; the second map is the final structure holding
944 // a mapping between Base and corresponding Derived relocate calls
945 DenseMap<std::pair<unsigned, unsigned>, GCRelocateInst *> RelocateIdxMap;
946 for (auto *ThisRelocate : AllRelocateCalls) {
947 auto K = std::make_pair(ThisRelocate->getBasePtrIndex(),
948 ThisRelocate->getDerivedPtrIndex());
949 RelocateIdxMap.insert(std::make_pair(K, ThisRelocate));
950 }
951 for (auto &Item : RelocateIdxMap) {
952 std::pair<unsigned, unsigned> Key = Item.first;
953 if (Key.first == Key.second)
954 // Base relocation: nothing to insert
955 continue;
956
957 GCRelocateInst *I = Item.second;
958 auto BaseKey = std::make_pair(Key.first, Key.first);
959
960 // We're iterating over RelocateIdxMap so we cannot modify it.
961 auto MaybeBase = RelocateIdxMap.find(BaseKey);
962 if (MaybeBase == RelocateIdxMap.end())
963 // TODO: We might want to insert a new base object relocate and gep off
964 // that, if there are enough derived object relocates.
965 continue;
966
967 RelocateInstMap[MaybeBase->second].push_back(I);
968 }
969}
970
971// Accepts a GEP and extracts the operands into a vector provided they're all
972// small integer constants
973static bool getGEPSmallConstantIntOffsetV(GetElementPtrInst *GEP,
974 SmallVectorImpl<Value *> &OffsetV) {
975 for (unsigned i = 1; i < GEP->getNumOperands(); i++) {
976 // Only accept small constant integer operands
977 auto Op = dyn_cast<ConstantInt>(GEP->getOperand(i));
978 if (!Op || Op->getZExtValue() > 20)
979 return false;
980 }
981
982 for (unsigned i = 1; i < GEP->getNumOperands(); i++)
983 OffsetV.push_back(GEP->getOperand(i));
984 return true;
985}
986
987// Takes a RelocatedBase (base pointer relocation instruction) and Targets to
988// replace, computes a replacement, and affects it.
989static bool
990simplifyRelocatesOffABase(GCRelocateInst *RelocatedBase,
991 const SmallVectorImpl<GCRelocateInst *> &Targets) {
992 bool MadeChange = false;
993 // We must ensure the relocation of derived pointer is defined after
994 // relocation of base pointer. If we find a relocation corresponding to base
995 // defined earlier than relocation of base then we move relocation of base
996 // right before found relocation. We consider only relocation in the same
997 // basic block as relocation of base. Relocations from other basic block will
998 // be skipped by optimization and we do not care about them.
999 for (auto R = RelocatedBase->getParent()->getFirstInsertionPt();
1000 &*R != RelocatedBase; ++R)
1001 if (auto RI = dyn_cast<GCRelocateInst>(R))
1002 if (RI->getStatepoint() == RelocatedBase->getStatepoint())
1003 if (RI->getBasePtrIndex() == RelocatedBase->getBasePtrIndex()) {
1004 RelocatedBase->moveBefore(RI);
1005 break;
1006 }
1007
1008 for (GCRelocateInst *ToReplace : Targets) {
1009 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\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 1010, __PRETTY_FUNCTION__))
1010 "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\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 1010, __PRETTY_FUNCTION__))
;
1011 if (ToReplace->getBasePtrIndex() == ToReplace->getDerivedPtrIndex()) {
1012 // A duplicate relocate call. TODO: coalesce duplicates.
1013 continue;
1014 }
1015
1016 if (RelocatedBase->getParent() != ToReplace->getParent()) {
1017 // Base and derived relocates are in different basic blocks.
1018 // In this case transform is only valid when base dominates derived
1019 // relocate. However it would be too expensive to check dominance
1020 // for each such relocate, so we skip the whole transformation.
1021 continue;
1022 }
1023
1024 Value *Base = ToReplace->getBasePtr();
1025 auto Derived = dyn_cast<GetElementPtrInst>(ToReplace->getDerivedPtr());
1026 if (!Derived || Derived->getPointerOperand() != Base)
1027 continue;
1028
1029 SmallVector<Value *, 2> OffsetV;
1030 if (!getGEPSmallConstantIntOffsetV(Derived, OffsetV))
1031 continue;
1032
1033 // Create a Builder and replace the target callsite with a gep
1034 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\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 1035, __PRETTY_FUNCTION__))
1035 "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\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 1035, __PRETTY_FUNCTION__))
;
1036
1037 // Insert after RelocatedBase
1038 IRBuilder<> Builder(RelocatedBase->getNextNode());
1039 Builder.SetCurrentDebugLocation(ToReplace->getDebugLoc());
1040
1041 // If gc_relocate does not match the actual type, cast it to the right type.
1042 // In theory, there must be a bitcast after gc_relocate if the type does not
1043 // match, and we should reuse it to get the derived pointer. But it could be
1044 // cases like this:
1045 // bb1:
1046 // ...
1047 // %g1 = call coldcc i8 addrspace(1)* @llvm.experimental.gc.relocate.p1i8(...)
1048 // br label %merge
1049 //
1050 // bb2:
1051 // ...
1052 // %g2 = call coldcc i8 addrspace(1)* @llvm.experimental.gc.relocate.p1i8(...)
1053 // br label %merge
1054 //
1055 // merge:
1056 // %p1 = phi i8 addrspace(1)* [ %g1, %bb1 ], [ %g2, %bb2 ]
1057 // %cast = bitcast i8 addrspace(1)* %p1 in to i32 addrspace(1)*
1058 //
1059 // In this case, we can not find the bitcast any more. So we insert a new bitcast
1060 // no matter there is already one or not. In this way, we can handle all cases, and
1061 // the extra bitcast should be optimized away in later passes.
1062 Value *ActualRelocatedBase = RelocatedBase;
1063 if (RelocatedBase->getType() != Base->getType()) {
1064 ActualRelocatedBase =
1065 Builder.CreateBitCast(RelocatedBase, Base->getType());
1066 }
1067 Value *Replacement = Builder.CreateGEP(
1068 Derived->getSourceElementType(), ActualRelocatedBase, makeArrayRef(OffsetV));
1069 Replacement->takeName(ToReplace);
1070 // If the newly generated derived pointer's type does not match the original derived
1071 // pointer's type, cast the new derived pointer to match it. Same reasoning as above.
1072 Value *ActualReplacement = Replacement;
1073 if (Replacement->getType() != ToReplace->getType()) {
1074 ActualReplacement =
1075 Builder.CreateBitCast(Replacement, ToReplace->getType());
1076 }
1077 ToReplace->replaceAllUsesWith(ActualReplacement);
1078 ToReplace->eraseFromParent();
1079
1080 MadeChange = true;
1081 }
1082 return MadeChange;
1083}
1084
1085// Turns this:
1086//
1087// %base = ...
1088// %ptr = gep %base + 15
1089// %tok = statepoint (%fun, i32 0, i32 0, i32 0, %base, %ptr)
1090// %base' = relocate(%tok, i32 4, i32 4)
1091// %ptr' = relocate(%tok, i32 4, i32 5)
1092// %val = load %ptr'
1093//
1094// into this:
1095//
1096// %base = ...
1097// %ptr = gep %base + 15
1098// %tok = statepoint (%fun, i32 0, i32 0, i32 0, %base, %ptr)
1099// %base' = gc.relocate(%tok, i32 4, i32 4)
1100// %ptr' = gep %base' + 15
1101// %val = load %ptr'
1102bool CodeGenPrepare::simplifyOffsetableRelocate(Instruction &I) {
1103 bool MadeChange = false;
1104 SmallVector<GCRelocateInst *, 2> AllRelocateCalls;
1105
1106 for (auto *U : I.users())
1107 if (GCRelocateInst *Relocate = dyn_cast<GCRelocateInst>(U))
1108 // Collect all the relocate calls associated with a statepoint
1109 AllRelocateCalls.push_back(Relocate);
1110
1111 // We need atleast one base pointer relocation + one derived pointer
1112 // relocation to mangle
1113 if (AllRelocateCalls.size() < 2)
1114 return false;
1115
1116 // RelocateInstMap is a mapping from the base relocate instruction to the
1117 // corresponding derived relocate instructions
1118 DenseMap<GCRelocateInst *, SmallVector<GCRelocateInst *, 2>> RelocateInstMap;
1119 computeBaseDerivedRelocateMap(AllRelocateCalls, RelocateInstMap);
1120 if (RelocateInstMap.empty())
1121 return false;
1122
1123 for (auto &Item : RelocateInstMap)
1124 // Item.first is the RelocatedBase to offset against
1125 // Item.second is the vector of Targets to replace
1126 MadeChange = simplifyRelocatesOffABase(Item.first, Item.second);
1127 return MadeChange;
1128}
1129
1130/// SinkCast - Sink the specified cast instruction into its user blocks
1131static bool SinkCast(CastInst *CI) {
1132 BasicBlock *DefBB = CI->getParent();
1133
1134 /// InsertedCasts - Only insert a cast in each block once.
1135 DenseMap<BasicBlock*, CastInst*> InsertedCasts;
1136
1137 bool MadeChange = false;
1138 for (Value::user_iterator UI = CI->user_begin(), E = CI->user_end();
1139 UI != E; ) {
1140 Use &TheUse = UI.getUse();
1141 Instruction *User = cast<Instruction>(*UI);
1142
1143 // Figure out which BB this cast is used in. For PHI's this is the
1144 // appropriate predecessor block.
1145 BasicBlock *UserBB = User->getParent();
1146 if (PHINode *PN = dyn_cast<PHINode>(User)) {
1147 UserBB = PN->getIncomingBlock(TheUse);
1148 }
1149
1150 // Preincrement use iterator so we don't invalidate it.
1151 ++UI;
1152
1153 // The first insertion point of a block containing an EH pad is after the
1154 // pad. If the pad is the user, we cannot sink the cast past the pad.
1155 if (User->isEHPad())
1156 continue;
1157
1158 // If the block selected to receive the cast is an EH pad that does not
1159 // allow non-PHI instructions before the terminator, we can't sink the
1160 // cast.
1161 if (UserBB->getTerminator()->isEHPad())
1162 continue;
1163
1164 // If this user is in the same block as the cast, don't change the cast.
1165 if (UserBB == DefBB) continue;
1166
1167 // If we have already inserted a cast into this block, use it.
1168 CastInst *&InsertedCast = InsertedCasts[UserBB];
1169
1170 if (!InsertedCast) {
1171 BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
1172 assert(InsertPt != UserBB->end())((InsertPt != UserBB->end()) ? static_cast<void> (0)
: __assert_fail ("InsertPt != UserBB->end()", "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 1172, __PRETTY_FUNCTION__))
;
1173 InsertedCast = CastInst::Create(CI->getOpcode(), CI->getOperand(0),
1174 CI->getType(), "", &*InsertPt);
1175 }
1176
1177 // Replace a use of the cast with a use of the new cast.
1178 TheUse = InsertedCast;
1179 MadeChange = true;
1180 ++NumCastUses;
1181 }
1182
1183 // If we removed all uses, nuke the cast.
1184 if (CI->use_empty()) {
1185 CI->eraseFromParent();
1186 MadeChange = true;
1187 }
1188
1189 return MadeChange;
1190}
1191
1192/// If the specified cast instruction is a noop copy (e.g. it's casting from
1193/// one pointer type to another, i32->i8 on PPC), sink it into user blocks to
1194/// reduce the number of virtual registers that must be created and coalesced.
1195///
1196/// Return true if any changes are made.
1197static bool OptimizeNoopCopyExpression(CastInst *CI, const TargetLowering &TLI,
1198 const DataLayout &DL) {
1199 // Sink only "cheap" (or nop) address-space casts. This is a weaker condition
1200 // than sinking only nop casts, but is helpful on some platforms.
1201 if (auto *ASC = dyn_cast<AddrSpaceCastInst>(CI)) {
1202 if (!TLI.isCheapAddrSpaceCast(ASC->getSrcAddressSpace(),
1203 ASC->getDestAddressSpace()))
1204 return false;
1205 }
1206
1207 // If this is a noop copy,
1208 EVT SrcVT = TLI.getValueType(DL, CI->getOperand(0)->getType());
1209 EVT DstVT = TLI.getValueType(DL, CI->getType());
1210
1211 // This is an fp<->int conversion?
1212 if (SrcVT.isInteger() != DstVT.isInteger())
1213 return false;
1214
1215 // If this is an extension, it will be a zero or sign extension, which
1216 // isn't a noop.
1217 if (SrcVT.bitsLT(DstVT)) return false;
1218
1219 // If these values will be promoted, find out what they will be promoted
1220 // to. This helps us consider truncates on PPC as noop copies when they
1221 // are.
1222 if (TLI.getTypeAction(CI->getContext(), SrcVT) ==
1223 TargetLowering::TypePromoteInteger)
1224 SrcVT = TLI.getTypeToTransformTo(CI->getContext(), SrcVT);
1225 if (TLI.getTypeAction(CI->getContext(), DstVT) ==
1226 TargetLowering::TypePromoteInteger)
1227 DstVT = TLI.getTypeToTransformTo(CI->getContext(), DstVT);
1228
1229 // If, after promotion, these are the same types, this is a noop copy.
1230 if (SrcVT != DstVT)
1231 return false;
1232
1233 return SinkCast(CI);
1234}
1235
1236/// Try to combine CI into a call to the llvm.uadd.with.overflow intrinsic if
1237/// possible.
1238///
1239/// Return true if any changes were made.
1240static bool CombineUAddWithOverflow(CmpInst *CI) {
1241 Value *A, *B;
1242 Instruction *AddI;
1243 if (!match(CI,
1244 m_UAddWithOverflow(m_Value(A), m_Value(B), m_Instruction(AddI))))
1245 return false;
1246
1247 Type *Ty = AddI->getType();
1248 if (!isa<IntegerType>(Ty))
1249 return false;
1250
1251 // We don't want to move around uses of condition values this late, so we we
1252 // check if it is legal to create the call to the intrinsic in the basic
1253 // block containing the icmp:
1254
1255 if (AddI->getParent() != CI->getParent() && !AddI->hasOneUse())
1256 return false;
1257
1258#ifndef NDEBUG
1259 // Someday m_UAddWithOverflow may get smarter, but this is a safe assumption
1260 // for now:
1261 if (AddI->hasOneUse())
1262 assert(*AddI->user_begin() == CI && "expected!")((*AddI->user_begin() == CI && "expected!") ? static_cast
<void> (0) : __assert_fail ("*AddI->user_begin() == CI && \"expected!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 1262, __PRETTY_FUNCTION__))
;
1263#endif
1264
1265 Module *M = CI->getModule();
1266 Value *F = Intrinsic::getDeclaration(M, Intrinsic::uadd_with_overflow, Ty);
1267
1268 auto *InsertPt = AddI->hasOneUse() ? CI : AddI;
1269
1270 auto *UAddWithOverflow =
1271 CallInst::Create(F, {A, B}, "uadd.overflow", InsertPt);
1272 auto *UAdd = ExtractValueInst::Create(UAddWithOverflow, 0, "uadd", InsertPt);
1273 auto *Overflow =
1274 ExtractValueInst::Create(UAddWithOverflow, 1, "overflow", InsertPt);
1275
1276 CI->replaceAllUsesWith(Overflow);
1277 AddI->replaceAllUsesWith(UAdd);
1278 CI->eraseFromParent();
1279 AddI->eraseFromParent();
1280 return true;
1281}
1282
1283/// Sink the given CmpInst into user blocks to reduce the number of virtual
1284/// registers that must be created and coalesced. This is a clear win except on
1285/// targets with multiple condition code registers (PowerPC), where it might
1286/// lose; some adjustment may be wanted there.
1287///
1288/// Return true if any changes are made.
1289static bool SinkCmpExpression(CmpInst *CI, const TargetLowering *TLI) {
1290 BasicBlock *DefBB = CI->getParent();
1291
1292 // Avoid sinking soft-FP comparisons, since this can move them into a loop.
1293 if (TLI && TLI->useSoftFloat() && isa<FCmpInst>(CI))
1294 return false;
1295
1296 // Only insert a cmp in each block once.
1297 DenseMap<BasicBlock*, CmpInst*> InsertedCmps;
1298
1299 bool MadeChange = false;
1300 for (Value::user_iterator UI = CI->user_begin(), E = CI->user_end();
1301 UI != E; ) {
1302 Use &TheUse = UI.getUse();
1303 Instruction *User = cast<Instruction>(*UI);
1304
1305 // Preincrement use iterator so we don't invalidate it.
1306 ++UI;
1307
1308 // Don't bother for PHI nodes.
1309 if (isa<PHINode>(User))
1310 continue;
1311
1312 // Figure out which BB this cmp is used in.
1313 BasicBlock *UserBB = User->getParent();
1314
1315 // If this user is in the same block as the cmp, don't change the cmp.
1316 if (UserBB == DefBB) continue;
1317
1318 // If we have already inserted a cmp into this block, use it.
1319 CmpInst *&InsertedCmp = InsertedCmps[UserBB];
1320
1321 if (!InsertedCmp) {
1322 BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
1323 assert(InsertPt != UserBB->end())((InsertPt != UserBB->end()) ? static_cast<void> (0)
: __assert_fail ("InsertPt != UserBB->end()", "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 1323, __PRETTY_FUNCTION__))
;
1324 InsertedCmp =
1325 CmpInst::Create(CI->getOpcode(), CI->getPredicate(),
1326 CI->getOperand(0), CI->getOperand(1), "", &*InsertPt);
1327 // Propagate the debug info.
1328 InsertedCmp->setDebugLoc(CI->getDebugLoc());
1329 }
1330
1331 // Replace a use of the cmp with a use of the new cmp.
1332 TheUse = InsertedCmp;
1333 MadeChange = true;
1334 ++NumCmpUses;
1335 }
1336
1337 // If we removed all uses, nuke the cmp.
1338 if (CI->use_empty()) {
1339 CI->eraseFromParent();
1340 MadeChange = true;
1341 }
1342
1343 return MadeChange;
1344}
1345
1346static bool OptimizeCmpExpression(CmpInst *CI, const TargetLowering *TLI) {
1347 if (SinkCmpExpression(CI, TLI))
1348 return true;
1349
1350 if (CombineUAddWithOverflow(CI))
1351 return true;
1352
1353 return false;
1354}
1355
1356/// Duplicate and sink the given 'and' instruction into user blocks where it is
1357/// used in a compare to allow isel to generate better code for targets where
1358/// this operation can be combined.
1359///
1360/// Return true if any changes are made.
1361static bool sinkAndCmp0Expression(Instruction *AndI,
1362 const TargetLowering &TLI,
1363 SetOfInstrs &InsertedInsts) {
1364 // Double-check that we're not trying to optimize an instruction that was
1365 // already optimized by some other part of this pass.
1366 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\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 1367, __PRETTY_FUNCTION__))
1367 "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\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 1367, __PRETTY_FUNCTION__))
;
1368 (void) InsertedInsts;
1369
1370 // Nothing to do for single use in same basic block.
1371 if (AndI->hasOneUse() &&
1372 AndI->getParent() == cast<Instruction>(*AndI->user_begin())->getParent())
1373 return false;
1374
1375 // Try to avoid cases where sinking/duplicating is likely to increase register
1376 // pressure.
1377 if (!isa<ConstantInt>(AndI->getOperand(0)) &&
1378 !isa<ConstantInt>(AndI->getOperand(1)) &&
1379 AndI->getOperand(0)->hasOneUse() && AndI->getOperand(1)->hasOneUse())
1380 return false;
1381
1382 for (auto *U : AndI->users()) {
1383 Instruction *User = cast<Instruction>(U);
1384
1385 // Only sink for and mask feeding icmp with 0.
1386 if (!isa<ICmpInst>(User))
1387 return false;
1388
1389 auto *CmpC = dyn_cast<ConstantInt>(User->getOperand(1));
1390 if (!CmpC || !CmpC->isZero())
1391 return false;
1392 }
1393
1394 if (!TLI.isMaskAndCmp0FoldingBeneficial(*AndI))
1395 return false;
1396
1397 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)
;
1398 DEBUG(AndI->getParent()->dump())do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { AndI->getParent()->dump(); } } while
(false)
;
1399
1400 // Push the 'and' into the same block as the icmp 0. There should only be
1401 // one (icmp (and, 0)) in each block, since CSE/GVN should have removed any
1402 // others, so we don't need to keep track of which BBs we insert into.
1403 for (Value::user_iterator UI = AndI->user_begin(), E = AndI->user_end();
1404 UI != E; ) {
1405 Use &TheUse = UI.getUse();
1406 Instruction *User = cast<Instruction>(*UI);
1407
1408 // Preincrement use iterator so we don't invalidate it.
1409 ++UI;
1410
1411 DEBUG(dbgs() << "sinking 'and' use: " << *User << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "sinking 'and' use: " <<
*User << "\n"; } } while (false)
;
1412
1413 // Keep the 'and' in the same place if the use is already in the same block.
1414 Instruction *InsertPt =
1415 User->getParent() == AndI->getParent() ? AndI : User;
1416 Instruction *InsertedAnd =
1417 BinaryOperator::Create(Instruction::And, AndI->getOperand(0),
1418 AndI->getOperand(1), "", InsertPt);
1419 // Propagate the debug info.
1420 InsertedAnd->setDebugLoc(AndI->getDebugLoc());
1421
1422 // Replace a use of the 'and' with a use of the new 'and'.
1423 TheUse = InsertedAnd;
1424 ++NumAndUses;
1425 DEBUG(User->getParent()->dump())do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { User->getParent()->dump(); } } while
(false)
;
1426 }
1427
1428 // We removed all uses, nuke the and.
1429 AndI->eraseFromParent();
1430 return true;
1431}
1432
1433/// Check if the candidates could be combined with a shift instruction, which
1434/// includes:
1435/// 1. Truncate instruction
1436/// 2. And instruction and the imm is a mask of the low bits:
1437/// imm & (imm+1) == 0
1438static bool isExtractBitsCandidateUse(Instruction *User) {
1439 if (!isa<TruncInst>(User)) {
1440 if (User->getOpcode() != Instruction::And ||
1441 !isa<ConstantInt>(User->getOperand(1)))
1442 return false;
1443
1444 const APInt &Cimm = cast<ConstantInt>(User->getOperand(1))->getValue();
1445
1446 if ((Cimm & (Cimm + 1)).getBoolValue())
1447 return false;
1448 }
1449 return true;
1450}
1451
1452/// Sink both shift and truncate instruction to the use of truncate's BB.
1453static bool
1454SinkShiftAndTruncate(BinaryOperator *ShiftI, Instruction *User, ConstantInt *CI,
1455 DenseMap<BasicBlock *, BinaryOperator *> &InsertedShifts,
1456 const TargetLowering &TLI, const DataLayout &DL) {
1457 BasicBlock *UserBB = User->getParent();
1458 DenseMap<BasicBlock *, CastInst *> InsertedTruncs;
1459 TruncInst *TruncI = dyn_cast<TruncInst>(User);
1460 bool MadeChange = false;
1461
1462 for (Value::user_iterator TruncUI = TruncI->user_begin(),
1463 TruncE = TruncI->user_end();
1464 TruncUI != TruncE;) {
1465
1466 Use &TruncTheUse = TruncUI.getUse();
1467 Instruction *TruncUser = cast<Instruction>(*TruncUI);
1468 // Preincrement use iterator so we don't invalidate it.
1469
1470 ++TruncUI;
1471
1472 int ISDOpcode = TLI.InstructionOpcodeToISD(TruncUser->getOpcode());
1473 if (!ISDOpcode)
1474 continue;
1475
1476 // If the use is actually a legal node, there will not be an
1477 // implicit truncate.
1478 // FIXME: always querying the result type is just an
1479 // approximation; some nodes' legality is determined by the
1480 // operand or other means. There's no good way to find out though.
1481 if (TLI.isOperationLegalOrCustom(
1482 ISDOpcode, TLI.getValueType(DL, TruncUser->getType(), true)))
1483 continue;
1484
1485 // Don't bother for PHI nodes.
1486 if (isa<PHINode>(TruncUser))
1487 continue;
1488
1489 BasicBlock *TruncUserBB = TruncUser->getParent();
1490
1491 if (UserBB == TruncUserBB)
1492 continue;
1493
1494 BinaryOperator *&InsertedShift = InsertedShifts[TruncUserBB];
1495 CastInst *&InsertedTrunc = InsertedTruncs[TruncUserBB];
1496
1497 if (!InsertedShift && !InsertedTrunc) {
1498 BasicBlock::iterator InsertPt = TruncUserBB->getFirstInsertionPt();
1499 assert(InsertPt != TruncUserBB->end())((InsertPt != TruncUserBB->end()) ? static_cast<void>
(0) : __assert_fail ("InsertPt != TruncUserBB->end()", "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 1499, __PRETTY_FUNCTION__))
;
1500 // Sink the shift
1501 if (ShiftI->getOpcode() == Instruction::AShr)
1502 InsertedShift = BinaryOperator::CreateAShr(ShiftI->getOperand(0), CI,
1503 "", &*InsertPt);
1504 else
1505 InsertedShift = BinaryOperator::CreateLShr(ShiftI->getOperand(0), CI,
1506 "", &*InsertPt);
1507
1508 // Sink the trunc
1509 BasicBlock::iterator TruncInsertPt = TruncUserBB->getFirstInsertionPt();
1510 TruncInsertPt++;
1511 assert(TruncInsertPt != TruncUserBB->end())((TruncInsertPt != TruncUserBB->end()) ? static_cast<void
> (0) : __assert_fail ("TruncInsertPt != TruncUserBB->end()"
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 1511, __PRETTY_FUNCTION__))
;
1512
1513 InsertedTrunc = CastInst::Create(TruncI->getOpcode(), InsertedShift,
1514 TruncI->getType(), "", &*TruncInsertPt);
1515
1516 MadeChange = true;
1517
1518 TruncTheUse = InsertedTrunc;
1519 }
1520 }
1521 return MadeChange;
1522}
1523
1524/// Sink the shift *right* instruction into user blocks if the uses could
1525/// potentially be combined with this shift instruction and generate BitExtract
1526/// instruction. It will only be applied if the architecture supports BitExtract
1527/// instruction. Here is an example:
1528/// BB1:
1529/// %x.extract.shift = lshr i64 %arg1, 32
1530/// BB2:
1531/// %x.extract.trunc = trunc i64 %x.extract.shift to i16
1532/// ==>
1533///
1534/// BB2:
1535/// %x.extract.shift.1 = lshr i64 %arg1, 32
1536/// %x.extract.trunc = trunc i64 %x.extract.shift.1 to i16
1537///
1538/// CodeGen will recoginze the pattern in BB2 and generate BitExtract
1539/// instruction.
1540/// Return true if any changes are made.
1541static bool OptimizeExtractBits(BinaryOperator *ShiftI, ConstantInt *CI,
1542 const TargetLowering &TLI,
1543 const DataLayout &DL) {
1544 BasicBlock *DefBB = ShiftI->getParent();
1545
1546 /// Only insert instructions in each block once.
1547 DenseMap<BasicBlock *, BinaryOperator *> InsertedShifts;
1548
1549 bool shiftIsLegal = TLI.isTypeLegal(TLI.getValueType(DL, ShiftI->getType()));
1550
1551 bool MadeChange = false;
1552 for (Value::user_iterator UI = ShiftI->user_begin(), E = ShiftI->user_end();
1553 UI != E;) {
1554 Use &TheUse = UI.getUse();
1555 Instruction *User = cast<Instruction>(*UI);
1556 // Preincrement use iterator so we don't invalidate it.
1557 ++UI;
1558
1559 // Don't bother for PHI nodes.
1560 if (isa<PHINode>(User))
1561 continue;
1562
1563 if (!isExtractBitsCandidateUse(User))
1564 continue;
1565
1566 BasicBlock *UserBB = User->getParent();
1567
1568 if (UserBB == DefBB) {
1569 // If the shift and truncate instruction are in the same BB. The use of
1570 // the truncate(TruncUse) may still introduce another truncate if not
1571 // legal. In this case, we would like to sink both shift and truncate
1572 // instruction to the BB of TruncUse.
1573 // for example:
1574 // BB1:
1575 // i64 shift.result = lshr i64 opnd, imm
1576 // trunc.result = trunc shift.result to i16
1577 //
1578 // BB2:
1579 // ----> We will have an implicit truncate here if the architecture does
1580 // not have i16 compare.
1581 // cmp i16 trunc.result, opnd2
1582 //
1583 if (isa<TruncInst>(User) && shiftIsLegal
1584 // If the type of the truncate is legal, no trucate will be
1585 // introduced in other basic blocks.
1586 &&
1587 (!TLI.isTypeLegal(TLI.getValueType(DL, User->getType()))))
1588 MadeChange =
1589 SinkShiftAndTruncate(ShiftI, User, CI, InsertedShifts, TLI, DL);
1590
1591 continue;
1592 }
1593 // If we have already inserted a shift into this block, use it.
1594 BinaryOperator *&InsertedShift = InsertedShifts[UserBB];
1595
1596 if (!InsertedShift) {
1597 BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
1598 assert(InsertPt != UserBB->end())((InsertPt != UserBB->end()) ? static_cast<void> (0)
: __assert_fail ("InsertPt != UserBB->end()", "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 1598, __PRETTY_FUNCTION__))
;
1599
1600 if (ShiftI->getOpcode() == Instruction::AShr)
1601 InsertedShift = BinaryOperator::CreateAShr(ShiftI->getOperand(0), CI,
1602 "", &*InsertPt);
1603 else
1604 InsertedShift = BinaryOperator::CreateLShr(ShiftI->getOperand(0), CI,
1605 "", &*InsertPt);
1606
1607 MadeChange = true;
1608 }
1609
1610 // Replace a use of the shift with a use of the new shift.
1611 TheUse = InsertedShift;
1612 }
1613
1614 // If we removed all uses, nuke the shift.
1615 if (ShiftI->use_empty())
1616 ShiftI->eraseFromParent();
1617
1618 return MadeChange;
1619}
1620
1621/// If counting leading or trailing zeros is an expensive operation and a zero
1622/// input is defined, add a check for zero to avoid calling the intrinsic.
1623///
1624/// We want to transform:
1625/// %z = call i64 @llvm.cttz.i64(i64 %A, i1 false)
1626///
1627/// into:
1628/// entry:
1629/// %cmpz = icmp eq i64 %A, 0
1630/// br i1 %cmpz, label %cond.end, label %cond.false
1631/// cond.false:
1632/// %z = call i64 @llvm.cttz.i64(i64 %A, i1 true)
1633/// br label %cond.end
1634/// cond.end:
1635/// %ctz = phi i64 [ 64, %entry ], [ %z, %cond.false ]
1636///
1637/// If the transform is performed, return true and set ModifiedDT to true.
1638static bool despeculateCountZeros(IntrinsicInst *CountZeros,
1639 const TargetLowering *TLI,
1640 const DataLayout *DL,
1641 bool &ModifiedDT) {
1642 if (!TLI || !DL)
1643 return false;
1644
1645 // If a zero input is undefined, it doesn't make sense to despeculate that.
1646 if (match(CountZeros->getOperand(1), m_One()))
1647 return false;
1648
1649 // If it's cheap to speculate, there's nothing to do.
1650 auto IntrinsicID = CountZeros->getIntrinsicID();
1651 if ((IntrinsicID == Intrinsic::cttz && TLI->isCheapToSpeculateCttz()) ||
1652 (IntrinsicID == Intrinsic::ctlz && TLI->isCheapToSpeculateCtlz()))
1653 return false;
1654
1655 // Only handle legal scalar cases. Anything else requires too much work.
1656 Type *Ty = CountZeros->getType();
1657 unsigned SizeInBits = Ty->getPrimitiveSizeInBits();
1658 if (Ty->isVectorTy() || SizeInBits > DL->getLargestLegalIntTypeSizeInBits())
1659 return false;
1660
1661 // The intrinsic will be sunk behind a compare against zero and branch.
1662 BasicBlock *StartBlock = CountZeros->getParent();
1663 BasicBlock *CallBlock = StartBlock->splitBasicBlock(CountZeros, "cond.false");
1664
1665 // Create another block after the count zero intrinsic. A PHI will be added
1666 // in this block to select the result of the intrinsic or the bit-width
1667 // constant if the input to the intrinsic is zero.
1668 BasicBlock::iterator SplitPt = ++(BasicBlock::iterator(CountZeros));
1669 BasicBlock *EndBlock = CallBlock->splitBasicBlock(SplitPt, "cond.end");
1670
1671 // Set up a builder to create a compare, conditional branch, and PHI.
1672 IRBuilder<> Builder(CountZeros->getContext());
1673 Builder.SetInsertPoint(StartBlock->getTerminator());
1674 Builder.SetCurrentDebugLocation(CountZeros->getDebugLoc());
1675
1676 // Replace the unconditional branch that was created by the first split with
1677 // a compare against zero and a conditional branch.
1678 Value *Zero = Constant::getNullValue(Ty);
1679 Value *Cmp = Builder.CreateICmpEQ(CountZeros->getOperand(0), Zero, "cmpz");
1680 Builder.CreateCondBr(Cmp, EndBlock, CallBlock);
1681 StartBlock->getTerminator()->eraseFromParent();
1682
1683 // Create a PHI in the end block to select either the output of the intrinsic
1684 // or the bit width of the operand.
1685 Builder.SetInsertPoint(&EndBlock->front());
1686 PHINode *PN = Builder.CreatePHI(Ty, 2, "ctz");
1687 CountZeros->replaceAllUsesWith(PN);
1688 Value *BitWidth = Builder.getInt(APInt(SizeInBits, SizeInBits));
1689 PN->addIncoming(BitWidth, StartBlock);
1690 PN->addIncoming(CountZeros, CallBlock);
1691
1692 // We are explicitly handling the zero case, so we can set the intrinsic's
1693 // undefined zero argument to 'true'. This will also prevent reprocessing the
1694 // intrinsic; we only despeculate when a zero input is defined.
1695 CountZeros->setArgOperand(1, Builder.getTrue());
1696 ModifiedDT = true;
1697 return true;
1698}
1699
1700namespace {
1701
1702// This class provides helper functions to expand a memcmp library call into an
1703// inline expansion.
1704class MemCmpExpansion {
1705 struct ResultBlock {
1706 BasicBlock *BB = nullptr;
1707 PHINode *PhiSrc1 = nullptr;
1708 PHINode *PhiSrc2 = nullptr;
1709
1710 ResultBlock() = default;
1711 };
1712
1713 CallInst *CI;
1714 ResultBlock ResBlock;
1715 unsigned MaxLoadSize;
1716 unsigned NumBlocks;
1717 unsigned NumBlocksNonOneByte;
1718 unsigned NumLoadsPerBlock;
1719 std::vector<BasicBlock *> LoadCmpBlocks;
1720 BasicBlock *EndBlock;
1721 PHINode *PhiRes;
1722 bool IsUsedForZeroCmp;
1723 const DataLayout &DL;
1724 IRBuilder<> Builder;
1725
1726 unsigned calculateNumBlocks(unsigned Size);
1727 void createLoadCmpBlocks();
1728 void createResultBlock();
1729 void setupResultBlockPHINodes();
1730 void setupEndBlockPHINodes();
1731 void emitLoadCompareBlock(unsigned Index, unsigned LoadSize,
1732 unsigned GEPIndex);
1733 Value *getCompareLoadPairs(unsigned Index, unsigned Size,
1734 unsigned &NumBytesProcessed);
1735 void emitLoadCompareBlockMultipleLoads(unsigned Index, unsigned Size,
1736 unsigned &NumBytesProcessed);
1737 void emitLoadCompareByteBlock(unsigned Index, unsigned GEPIndex);
1738 void emitMemCmpResultBlock();
1739 Value *getMemCmpExpansionZeroCase(unsigned Size);
1740 Value *getMemCmpEqZeroOneBlock(unsigned Size);
1741 Value *getMemCmpOneBlock(unsigned Size);
1742 unsigned getLoadSize(unsigned Size);
1743 unsigned getNumLoads(unsigned Size);
1744
1745public:
1746 MemCmpExpansion(CallInst *CI, uint64_t Size, unsigned MaxLoadSize,
1747 unsigned NumLoadsPerBlock, const DataLayout &DL);
1748
1749 Value *getMemCmpExpansion(uint64_t Size);
1750};
1751
1752} // end anonymous namespace
1753
1754// Initialize the basic block structure required for expansion of memcmp call
1755// with given maximum load size and memcmp size parameter.
1756// This structure includes:
1757// 1. A list of load compare blocks - LoadCmpBlocks.
1758// 2. An EndBlock, split from original instruction point, which is the block to
1759// return from.
1760// 3. ResultBlock, block to branch to for early exit when a
1761// LoadCmpBlock finds a difference.
1762MemCmpExpansion::MemCmpExpansion(CallInst *CI, uint64_t Size,
1763 unsigned MaxLoadSize, unsigned LoadsPerBlock,
1764 const DataLayout &TheDataLayout)
1765 : CI(CI), MaxLoadSize(MaxLoadSize), NumLoadsPerBlock(LoadsPerBlock),
1766 DL(TheDataLayout), Builder(CI) {
1767 // A memcmp with zero-comparison with only one block of load and compare does
1768 // not need to set up any extra blocks. This case could be handled in the DAG,
1769 // but since we have all of the machinery to flexibly expand any memcpy here,
1770 // we choose to handle this case too to avoid fragmented lowering.
1771 IsUsedForZeroCmp = isOnlyUsedInZeroEqualityComparison(CI);
1772 NumBlocks = calculateNumBlocks(Size);
1773 if ((!IsUsedForZeroCmp && NumLoadsPerBlock != 1) || NumBlocks != 1) {
1774 BasicBlock *StartBlock = CI->getParent();
1775 EndBlock = StartBlock->splitBasicBlock(CI, "endblock");
1776 setupEndBlockPHINodes();
1777 createResultBlock();
1778
1779 // If return value of memcmp is not used in a zero equality, we need to
1780 // calculate which source was larger. The calculation requires the
1781 // two loaded source values of each load compare block.
1782 // These will be saved in the phi nodes created by setupResultBlockPHINodes.
1783 if (!IsUsedForZeroCmp)
1784 setupResultBlockPHINodes();
1785
1786 // Create the number of required load compare basic blocks.
1787 createLoadCmpBlocks();
1788
1789 // Update the terminator added by splitBasicBlock to branch to the first
1790 // LoadCmpBlock.
1791 StartBlock->getTerminator()->setSuccessor(0, LoadCmpBlocks[0]);
1792 }
1793
1794 Builder.SetCurrentDebugLocation(CI->getDebugLoc());
1795}
1796
1797void MemCmpExpansion::createLoadCmpBlocks() {
1798 for (unsigned i = 0; i < NumBlocks; i++) {
1799 BasicBlock *BB = BasicBlock::Create(CI->getContext(), "loadbb",
1800 EndBlock->getParent(), EndBlock);
1801 LoadCmpBlocks.push_back(BB);
1802 }
1803}
1804
1805void MemCmpExpansion::createResultBlock() {
1806 ResBlock.BB = BasicBlock::Create(CI->getContext(), "res_block",
1807 EndBlock->getParent(), EndBlock);
1808}
1809
1810// This function creates the IR instructions for loading and comparing 1 byte.
1811// It loads 1 byte from each source of the memcmp parameters with the given
1812// GEPIndex. It then subtracts the two loaded values and adds this result to the
1813// final phi node for selecting the memcmp result.
1814void MemCmpExpansion::emitLoadCompareByteBlock(unsigned Index,
1815 unsigned GEPIndex) {
1816 Value *Source1 = CI->getArgOperand(0);
1817 Value *Source2 = CI->getArgOperand(1);
1818
1819 Builder.SetInsertPoint(LoadCmpBlocks[Index]);
1820 Type *LoadSizeType = Type::getInt8Ty(CI->getContext());
1821 // Cast source to LoadSizeType*.
1822 if (Source1->getType() != LoadSizeType)
1823 Source1 = Builder.CreateBitCast(Source1, LoadSizeType->getPointerTo());
1824 if (Source2->getType() != LoadSizeType)
1825 Source2 = Builder.CreateBitCast(Source2, LoadSizeType->getPointerTo());
1826
1827 // Get the base address using the GEPIndex.
1828 if (GEPIndex != 0) {
1829 Source1 = Builder.CreateGEP(LoadSizeType, Source1,
1830 ConstantInt::get(LoadSizeType, GEPIndex));
1831 Source2 = Builder.CreateGEP(LoadSizeType, Source2,
1832 ConstantInt::get(LoadSizeType, GEPIndex));
1833 }
1834
1835 Value *LoadSrc1 = Builder.CreateLoad(LoadSizeType, Source1);
1836 Value *LoadSrc2 = Builder.CreateLoad(LoadSizeType, Source2);
1837
1838 LoadSrc1 = Builder.CreateZExt(LoadSrc1, Type::getInt32Ty(CI->getContext()));
1839 LoadSrc2 = Builder.CreateZExt(LoadSrc2, Type::getInt32Ty(CI->getContext()));
1840 Value *Diff = Builder.CreateSub(LoadSrc1, LoadSrc2);
1841
1842 PhiRes->addIncoming(Diff, LoadCmpBlocks[Index]);
1843
1844 if (Index < (LoadCmpBlocks.size() - 1)) {
1845 // Early exit branch if difference found to EndBlock. Otherwise, continue to
1846 // next LoadCmpBlock,
1847 Value *Cmp = Builder.CreateICmp(ICmpInst::ICMP_NE, Diff,
1848 ConstantInt::get(Diff->getType(), 0));
1849 BranchInst *CmpBr =
1850 BranchInst::Create(EndBlock, LoadCmpBlocks[Index + 1], Cmp);
1851 Builder.Insert(CmpBr);
1852 } else {
1853 // The last block has an unconditional branch to EndBlock.
1854 BranchInst *CmpBr = BranchInst::Create(EndBlock);
1855 Builder.Insert(CmpBr);
1856 }
1857}
1858
1859unsigned MemCmpExpansion::getNumLoads(unsigned Size) {
1860 return (Size / MaxLoadSize) + countPopulation(Size % MaxLoadSize);
1861}
1862
1863unsigned MemCmpExpansion::getLoadSize(unsigned Size) {
1864 return MinAlign(PowerOf2Floor(Size), MaxLoadSize);
1865}
1866
1867/// Generate an equality comparison for one or more pairs of loaded values.
1868/// This is used in the case where the memcmp() call is compared equal or not
1869/// equal to zero.
1870Value *MemCmpExpansion::getCompareLoadPairs(unsigned Index, unsigned Size,
1871 unsigned &NumBytesProcessed) {
1872 std::vector<Value *> XorList, OrList;
1873 Value *Diff;
5
'Diff' declared without an initial value
1874
1875 unsigned RemainingBytes = Size - NumBytesProcessed;
1876 unsigned NumLoadsRemaining = getNumLoads(RemainingBytes);
1877 unsigned NumLoads = std::min(NumLoadsRemaining, NumLoadsPerBlock);
1878
1879 // For a single-block expansion, start inserting before the memcmp call.
1880 if (LoadCmpBlocks.empty())
6
Assuming the condition is false
7
Taking false branch
1881 Builder.SetInsertPoint(CI);
1882 else
1883 Builder.SetInsertPoint(LoadCmpBlocks[Index]);
1884
1885 Value *Cmp = nullptr;
1886 for (unsigned i = 0; i < NumLoads; ++i) {
8
Assuming 'i' is >= 'NumLoads'
9
Loop condition is false. Execution continues on line 1945
1887 unsigned LoadSize = getLoadSize(RemainingBytes);
1888 unsigned GEPIndex = NumBytesProcessed / LoadSize;
1889 NumBytesProcessed += LoadSize;
1890 RemainingBytes -= LoadSize;
1891
1892 Type *LoadSizeType = IntegerType::get(CI->getContext(), LoadSize * 8);
1893 Type *MaxLoadType = IntegerType::get(CI->getContext(), MaxLoadSize * 8);
1894 assert(LoadSize <= MaxLoadSize && "Unexpected load type")((LoadSize <= MaxLoadSize && "Unexpected load type"
) ? static_cast<void> (0) : __assert_fail ("LoadSize <= MaxLoadSize && \"Unexpected load type\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 1894, __PRETTY_FUNCTION__))
;
1895
1896 Value *Source1 = CI->getArgOperand(0);
1897 Value *Source2 = CI->getArgOperand(1);
1898
1899 // Cast source to LoadSizeType*.
1900 if (Source1->getType() != LoadSizeType)
1901 Source1 = Builder.CreateBitCast(Source1, LoadSizeType->getPointerTo());
1902 if (Source2->getType() != LoadSizeType)
1903 Source2 = Builder.CreateBitCast(Source2, LoadSizeType->getPointerTo());
1904
1905 // Get the base address using the GEPIndex.
1906 if (GEPIndex != 0) {
1907 Source1 = Builder.CreateGEP(LoadSizeType, Source1,
1908 ConstantInt::get(LoadSizeType, GEPIndex));
1909 Source2 = Builder.CreateGEP(LoadSizeType, Source2,
1910 ConstantInt::get(LoadSizeType, GEPIndex));
1911 }
1912
1913 // Get a constant or load a value for each source address.
1914 Value *LoadSrc1 = nullptr;
1915 if (auto *Source1C = dyn_cast<Constant>(Source1))
1916 LoadSrc1 = ConstantFoldLoadFromConstPtr(Source1C, LoadSizeType, DL);
1917 if (!LoadSrc1)
1918 LoadSrc1 = Builder.CreateLoad(LoadSizeType, Source1);
1919
1920 Value *LoadSrc2 = nullptr;
1921 if (auto *Source2C = dyn_cast<Constant>(Source2))
1922 LoadSrc2 = ConstantFoldLoadFromConstPtr(Source2C, LoadSizeType, DL);
1923 if (!LoadSrc2)
1924 LoadSrc2 = Builder.CreateLoad(LoadSizeType, Source2);
1925
1926 if (NumLoads != 1) {
1927 if (LoadSizeType != MaxLoadType) {
1928 LoadSrc1 = Builder.CreateZExt(LoadSrc1, MaxLoadType);
1929 LoadSrc2 = Builder.CreateZExt(LoadSrc2, MaxLoadType);
1930 }
1931 // If we have multiple loads per block, we need to generate a composite
1932 // comparison using xor+or.
1933 Diff = Builder.CreateXor(LoadSrc1, LoadSrc2);
1934 Diff = Builder.CreateZExt(Diff, MaxLoadType);
1935 XorList.push_back(Diff);
1936 } else {
1937 // If there's only one load per block, we just compare the loaded values.
1938 Cmp = Builder.CreateICmpNE(LoadSrc1, LoadSrc2);
1939 }
1940 }
1941
1942 auto pairWiseOr = [&](std::vector<Value *> &InList) -> std::vector<Value *> {
1943 std::vector<Value *> OutList;
1944 for (unsigned i = 0; i < InList.size() - 1; i = i + 2) {
1945 Value *Or = Builder.CreateOr(InList[i], InList[i + 1]);
1946 OutList.push_back(Or);
1947 }
1948 if (InList.size() % 2 != 0)
1949 OutList.push_back(InList.back());
1950 return OutList;
1951 };
1952
1953 if (!Cmp) {
10
Taking true branch
1954 // Pairwise OR the XOR results.
1955 OrList = pairWiseOr(XorList);
1956
1957 // Pairwise OR the OR results until one result left.
1958 while (OrList.size() != 1) {
11
Assuming the condition is false
12
Loop condition is false. Execution continues on line 1961
1959 OrList = pairWiseOr(OrList);
1960 }
1961 Cmp = Builder.CreateICmpNE(OrList[0], ConstantInt::get(Diff->getType(), 0));
13
Called C++ object pointer is uninitialized
1962 }
1963
1964 return Cmp;
1965}
1966
1967void MemCmpExpansion::emitLoadCompareBlockMultipleLoads(
1968 unsigned Index, unsigned Size, unsigned &NumBytesProcessed) {
1969 Value *Cmp = getCompareLoadPairs(Index, Size, NumBytesProcessed);
4
Calling 'MemCmpExpansion::getCompareLoadPairs'
1970
1971 BasicBlock *NextBB = (Index == (LoadCmpBlocks.size() - 1))
1972 ? EndBlock
1973 : LoadCmpBlocks[Index + 1];
1974 // Early exit branch if difference found to ResultBlock. Otherwise,
1975 // continue to next LoadCmpBlock or EndBlock.
1976 BranchInst *CmpBr = BranchInst::Create(ResBlock.BB, NextBB, Cmp);
1977 Builder.Insert(CmpBr);
1978
1979 // Add a phi edge for the last LoadCmpBlock to Endblock with a value of 0
1980 // since early exit to ResultBlock was not taken (no difference was found in
1981 // any of the bytes).
1982 if (Index == LoadCmpBlocks.size() - 1) {
1983 Value *Zero = ConstantInt::get(Type::getInt32Ty(CI->getContext()), 0);
1984 PhiRes->addIncoming(Zero, LoadCmpBlocks[Index]);
1985 }
1986}
1987
1988// This function creates the IR intructions for loading and comparing using the
1989// given LoadSize. It loads the number of bytes specified by LoadSize from each
1990// source of the memcmp parameters. It then does a subtract to see if there was
1991// a difference in the loaded values. If a difference is found, it branches
1992// with an early exit to the ResultBlock for calculating which source was
1993// larger. Otherwise, it falls through to the either the next LoadCmpBlock or
1994// the EndBlock if this is the last LoadCmpBlock. Loading 1 byte is handled with
1995// a special case through emitLoadCompareByteBlock. The special handling can
1996// simply subtract the loaded values and add it to the result phi node.
1997void MemCmpExpansion::emitLoadCompareBlock(unsigned Index, unsigned LoadSize,
1998 unsigned GEPIndex) {
1999 if (LoadSize == 1) {
2000 MemCmpExpansion::emitLoadCompareByteBlock(Index, GEPIndex);
2001 return;
2002 }
2003
2004 Type *LoadSizeType = IntegerType::get(CI->getContext(), LoadSize * 8);
2005 Type *MaxLoadType = IntegerType::get(CI->getContext(), MaxLoadSize * 8);
2006 assert(LoadSize <= MaxLoadSize && "Unexpected load type")((LoadSize <= MaxLoadSize && "Unexpected load type"
) ? static_cast<void> (0) : __assert_fail ("LoadSize <= MaxLoadSize && \"Unexpected load type\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 2006, __PRETTY_FUNCTION__))
;
2007
2008 Value *Source1 = CI->getArgOperand(0);
2009 Value *Source2 = CI->getArgOperand(1);
2010
2011 Builder.SetInsertPoint(LoadCmpBlocks[Index]);
2012 // Cast source to LoadSizeType*.
2013 if (Source1->getType() != LoadSizeType)
2014 Source1 = Builder.CreateBitCast(Source1, LoadSizeType->getPointerTo());
2015 if (Source2->getType() != LoadSizeType)
2016 Source2 = Builder.CreateBitCast(Source2, LoadSizeType->getPointerTo());
2017
2018 // Get the base address using the GEPIndex.
2019 if (GEPIndex != 0) {
2020 Source1 = Builder.CreateGEP(LoadSizeType, Source1,
2021 ConstantInt::get(LoadSizeType, GEPIndex));
2022 Source2 = Builder.CreateGEP(LoadSizeType, Source2,
2023 ConstantInt::get(LoadSizeType, GEPIndex));
2024 }
2025
2026 // Load LoadSizeType from the base address.
2027 Value *LoadSrc1 = Builder.CreateLoad(LoadSizeType, Source1);
2028 Value *LoadSrc2 = Builder.CreateLoad(LoadSizeType, Source2);
2029
2030 if (DL.isLittleEndian()) {
2031 Function *Bswap = Intrinsic::getDeclaration(CI->getModule(),
2032 Intrinsic::bswap, LoadSizeType);
2033 LoadSrc1 = Builder.CreateCall(Bswap, LoadSrc1);
2034 LoadSrc2 = Builder.CreateCall(Bswap, LoadSrc2);
2035 }
2036
2037 if (LoadSizeType != MaxLoadType) {
2038 LoadSrc1 = Builder.CreateZExt(LoadSrc1, MaxLoadType);
2039 LoadSrc2 = Builder.CreateZExt(LoadSrc2, MaxLoadType);
2040 }
2041
2042 // Add the loaded values to the phi nodes for calculating memcmp result only
2043 // if result is not used in a zero equality.
2044 if (!IsUsedForZeroCmp) {
2045 ResBlock.PhiSrc1->addIncoming(LoadSrc1, LoadCmpBlocks[Index]);
2046 ResBlock.PhiSrc2->addIncoming(LoadSrc2, LoadCmpBlocks[Index]);
2047 }
2048
2049 Value *Cmp = Builder.CreateICmp(ICmpInst::ICMP_EQ, LoadSrc1, LoadSrc2);
2050 BasicBlock *NextBB = (Index == (LoadCmpBlocks.size() - 1))
2051 ? EndBlock
2052 : LoadCmpBlocks[Index + 1];
2053 // Early exit branch if difference found to ResultBlock. Otherwise, continue
2054 // to next LoadCmpBlock or EndBlock.
2055 BranchInst *CmpBr = BranchInst::Create(NextBB, ResBlock.BB, Cmp);
2056 Builder.Insert(CmpBr);
2057
2058 // Add a phi edge for the last LoadCmpBlock to Endblock with a value of 0
2059 // since early exit to ResultBlock was not taken (no difference was found in
2060 // any of the bytes).
2061 if (Index == LoadCmpBlocks.size() - 1) {
2062 Value *Zero = ConstantInt::get(Type::getInt32Ty(CI->getContext()), 0);
2063 PhiRes->addIncoming(Zero, LoadCmpBlocks[Index]);
2064 }
2065}
2066
2067// This function populates the ResultBlock with a sequence to calculate the
2068// memcmp result. It compares the two loaded source values and returns -1 if
2069// src1 < src2 and 1 if src1 > src2.
2070void MemCmpExpansion::emitMemCmpResultBlock() {
2071 // Special case: if memcmp result is used in a zero equality, result does not
2072 // need to be calculated and can simply return 1.
2073 if (IsUsedForZeroCmp) {
2074 BasicBlock::iterator InsertPt = ResBlock.BB->getFirstInsertionPt();
2075 Builder.SetInsertPoint(ResBlock.BB, InsertPt);
2076 Value *Res = ConstantInt::get(Type::getInt32Ty(CI->getContext()), 1);
2077 PhiRes->addIncoming(Res, ResBlock.BB);
2078 BranchInst *NewBr = BranchInst::Create(EndBlock);
2079 Builder.Insert(NewBr);
2080 return;
2081 }
2082 BasicBlock::iterator InsertPt = ResBlock.BB->getFirstInsertionPt();
2083 Builder.SetInsertPoint(ResBlock.BB, InsertPt);
2084
2085 Value *Cmp = Builder.CreateICmp(ICmpInst::ICMP_ULT, ResBlock.PhiSrc1,
2086 ResBlock.PhiSrc2);
2087
2088 Value *Res =
2089 Builder.CreateSelect(Cmp, ConstantInt::get(Builder.getInt32Ty(), -1),
2090 ConstantInt::get(Builder.getInt32Ty(), 1));
2091
2092 BranchInst *NewBr = BranchInst::Create(EndBlock);
2093 Builder.Insert(NewBr);
2094 PhiRes->addIncoming(Res, ResBlock.BB);
2095}
2096
2097unsigned MemCmpExpansion::calculateNumBlocks(unsigned Size) {
2098 unsigned NumBlocks = 0;
2099 bool HaveOneByteLoad = false;
2100 unsigned RemainingSize = Size;
2101 unsigned LoadSize = MaxLoadSize;
2102 while (RemainingSize) {
2103 if (LoadSize == 1)
2104 HaveOneByteLoad = true;
2105 NumBlocks += RemainingSize / LoadSize;
2106 RemainingSize = RemainingSize % LoadSize;
2107 LoadSize = LoadSize / 2;
2108 }
2109 NumBlocksNonOneByte = HaveOneByteLoad ? (NumBlocks - 1) : NumBlocks;
2110
2111 if (IsUsedForZeroCmp)
2112 NumBlocks = NumBlocks / NumLoadsPerBlock +
2113 (NumBlocks % NumLoadsPerBlock != 0 ? 1 : 0);
2114
2115 return NumBlocks;
2116}
2117
2118void MemCmpExpansion::setupResultBlockPHINodes() {
2119 Type *MaxLoadType = IntegerType::get(CI->getContext(), MaxLoadSize * 8);
2120 Builder.SetInsertPoint(ResBlock.BB);
2121 ResBlock.PhiSrc1 =
2122 Builder.CreatePHI(MaxLoadType, NumBlocksNonOneByte, "phi.src1");
2123 ResBlock.PhiSrc2 =
2124 Builder.CreatePHI(MaxLoadType, NumBlocksNonOneByte, "phi.src2");
2125}
2126
2127void MemCmpExpansion::setupEndBlockPHINodes() {
2128 Builder.SetInsertPoint(&EndBlock->front());
2129 PhiRes = Builder.CreatePHI(Type::getInt32Ty(CI->getContext()), 2, "phi.res");
2130}
2131
2132Value *MemCmpExpansion::getMemCmpExpansionZeroCase(unsigned Size) {
2133 unsigned NumBytesProcessed = 0;
2134 // This loop populates each of the LoadCmpBlocks with the IR sequence to
2135 // handle multiple loads per block.
2136 for (unsigned i = 0; i < NumBlocks; ++i)
1
Assuming the condition is true
2
Loop condition is true. Entering loop body
2137 emitLoadCompareBlockMultipleLoads(i, Size, NumBytesProcessed);
3
Calling 'MemCmpExpansion::emitLoadCompareBlockMultipleLoads'
2138
2139 emitMemCmpResultBlock();
2140 return PhiRes;
2141}
2142
2143/// A memcmp expansion that compares equality with 0 and only has one block of
2144/// load and compare can bypass the compare, branch, and phi IR that is required
2145/// in the general case.
2146Value *MemCmpExpansion::getMemCmpEqZeroOneBlock(unsigned Size) {
2147 unsigned NumBytesProcessed = 0;
2148 Value *Cmp = getCompareLoadPairs(0, Size, NumBytesProcessed);
2149 return Builder.CreateZExt(Cmp, Type::getInt32Ty(CI->getContext()));
2150}
2151
2152/// A memcmp expansion that only has one block of load and compare can bypass
2153/// the compare, branch, and phi IR that is required in the general case.
2154Value *MemCmpExpansion::getMemCmpOneBlock(unsigned Size) {
2155 assert(NumLoadsPerBlock == 1 && "Only handles one load pair per block")((NumLoadsPerBlock == 1 && "Only handles one load pair per block"
) ? static_cast<void> (0) : __assert_fail ("NumLoadsPerBlock == 1 && \"Only handles one load pair per block\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 2155, __PRETTY_FUNCTION__))
;
2156
2157 Type *LoadSizeType = IntegerType::get(CI->getContext(), Size * 8);
2158 Value *Source1 = CI->getArgOperand(0);
2159 Value *Source2 = CI->getArgOperand(1);
2160
2161 // Cast source to LoadSizeType*.
2162 if (Source1->getType() != LoadSizeType)
2163 Source1 = Builder.CreateBitCast(Source1, LoadSizeType->getPointerTo());
2164 if (Source2->getType() != LoadSizeType)
2165 Source2 = Builder.CreateBitCast(Source2, LoadSizeType->getPointerTo());
2166
2167 // Load LoadSizeType from the base address.
2168 Value *LoadSrc1 = Builder.CreateLoad(LoadSizeType, Source1);
2169 Value *LoadSrc2 = Builder.CreateLoad(LoadSizeType, Source2);
2170
2171 if (DL.isLittleEndian() && Size != 1) {
2172 Function *Bswap = Intrinsic::getDeclaration(CI->getModule(),
2173 Intrinsic::bswap, LoadSizeType);
2174 LoadSrc1 = Builder.CreateCall(Bswap, LoadSrc1);
2175 LoadSrc2 = Builder.CreateCall(Bswap, LoadSrc2);
2176 }
2177
2178 if (Size < 4) {
2179 // The i8 and i16 cases don't need compares. We zext the loaded values and
2180 // subtract them to get the suitable negative, zero, or positive i32 result.
2181 LoadSrc1 = Builder.CreateZExt(LoadSrc1, Builder.getInt32Ty());
2182 LoadSrc2 = Builder.CreateZExt(LoadSrc2, Builder.getInt32Ty());
2183 return Builder.CreateSub(LoadSrc1, LoadSrc2);
2184 }
2185
2186 // The result of memcmp is negative, zero, or positive, so produce that by
2187 // subtracting 2 extended compare bits: sub (ugt, ult).
2188 // If a target prefers to use selects to get -1/0/1, they should be able
2189 // to transform this later. The inverse transform (going from selects to math)
2190 // may not be possible in the DAG because the selects got converted into
2191 // branches before we got there.
2192 Value *CmpUGT = Builder.CreateICmpUGT(LoadSrc1, LoadSrc2);
2193 Value *CmpULT = Builder.CreateICmpULT(LoadSrc1, LoadSrc2);
2194 Value *ZextUGT = Builder.CreateZExt(CmpUGT, Builder.getInt32Ty());
2195 Value *ZextULT = Builder.CreateZExt(CmpULT, Builder.getInt32Ty());
2196 return Builder.CreateSub(ZextUGT, ZextULT);
2197}
2198
2199// This function expands the memcmp call into an inline expansion and returns
2200// the memcmp result.
2201Value *MemCmpExpansion::getMemCmpExpansion(uint64_t Size) {
2202 if (IsUsedForZeroCmp)
2203 return NumBlocks == 1 ? getMemCmpEqZeroOneBlock(Size) :
2204 getMemCmpExpansionZeroCase(Size);
2205
2206 // TODO: Handle more than one load pair per block in getMemCmpOneBlock().
2207 if (NumBlocks == 1 && NumLoadsPerBlock == 1)
2208 return getMemCmpOneBlock(Size);
2209
2210 // This loop calls emitLoadCompareBlock for comparing Size bytes of the two
2211 // memcmp sources. It starts with loading using the maximum load size set by
2212 // the target. It processes any remaining bytes using a load size which is the
2213 // next smallest power of 2.
2214 unsigned LoadSize = MaxLoadSize;
2215 unsigned NumBytesToBeProcessed = Size;
2216 unsigned Index = 0;
2217 while (NumBytesToBeProcessed) {
2218 // Calculate how many blocks we can create with the current load size.
2219 unsigned NumBlocks = NumBytesToBeProcessed / LoadSize;
2220 unsigned GEPIndex = (Size - NumBytesToBeProcessed) / LoadSize;
2221 NumBytesToBeProcessed = NumBytesToBeProcessed % LoadSize;
2222
2223 // For each NumBlocks, populate the instruction sequence for loading and
2224 // comparing LoadSize bytes.
2225 while (NumBlocks--) {
2226 emitLoadCompareBlock(Index, LoadSize, GEPIndex);
2227 Index++;
2228 GEPIndex++;
2229 }
2230 // Get the next LoadSize to use.
2231 LoadSize = LoadSize / 2;
2232 }
2233
2234 emitMemCmpResultBlock();
2235 return PhiRes;
2236}
2237
2238// This function checks to see if an expansion of memcmp can be generated.
2239// It checks for constant compare size that is less than the max inline size.
2240// If an expansion cannot occur, returns false to leave as a library call.
2241// Otherwise, the library call is replaced with a new IR instruction sequence.
2242/// We want to transform:
2243/// %call = call signext i32 @memcmp(i8* %0, i8* %1, i64 15)
2244/// To:
2245/// loadbb:
2246/// %0 = bitcast i32* %buffer2 to i8*
2247/// %1 = bitcast i32* %buffer1 to i8*
2248/// %2 = bitcast i8* %1 to i64*
2249/// %3 = bitcast i8* %0 to i64*
2250/// %4 = load i64, i64* %2
2251/// %5 = load i64, i64* %3
2252/// %6 = call i64 @llvm.bswap.i64(i64 %4)
2253/// %7 = call i64 @llvm.bswap.i64(i64 %5)
2254/// %8 = sub i64 %6, %7
2255/// %9 = icmp ne i64 %8, 0
2256/// br i1 %9, label %res_block, label %loadbb1
2257/// res_block: ; preds = %loadbb2,
2258/// %loadbb1, %loadbb
2259/// %phi.src1 = phi i64 [ %6, %loadbb ], [ %22, %loadbb1 ], [ %36, %loadbb2 ]
2260/// %phi.src2 = phi i64 [ %7, %loadbb ], [ %23, %loadbb1 ], [ %37, %loadbb2 ]
2261/// %10 = icmp ult i64 %phi.src1, %phi.src2
2262/// %11 = select i1 %10, i32 -1, i32 1
2263/// br label %endblock
2264/// loadbb1: ; preds = %loadbb
2265/// %12 = bitcast i32* %buffer2 to i8*
2266/// %13 = bitcast i32* %buffer1 to i8*
2267/// %14 = bitcast i8* %13 to i32*
2268/// %15 = bitcast i8* %12 to i32*
2269/// %16 = getelementptr i32, i32* %14, i32 2
2270/// %17 = getelementptr i32, i32* %15, i32 2
2271/// %18 = load i32, i32* %16
2272/// %19 = load i32, i32* %17
2273/// %20 = call i32 @llvm.bswap.i32(i32 %18)
2274/// %21 = call i32 @llvm.bswap.i32(i32 %19)
2275/// %22 = zext i32 %20 to i64
2276/// %23 = zext i32 %21 to i64
2277/// %24 = sub i64 %22, %23
2278/// %25 = icmp ne i64 %24, 0
2279/// br i1 %25, label %res_block, label %loadbb2
2280/// loadbb2: ; preds = %loadbb1
2281/// %26 = bitcast i32* %buffer2 to i8*
2282/// %27 = bitcast i32* %buffer1 to i8*
2283/// %28 = bitcast i8* %27 to i16*
2284/// %29 = bitcast i8* %26 to i16*
2285/// %30 = getelementptr i16, i16* %28, i16 6
2286/// %31 = getelementptr i16, i16* %29, i16 6
2287/// %32 = load i16, i16* %30
2288/// %33 = load i16, i16* %31
2289/// %34 = call i16 @llvm.bswap.i16(i16 %32)
2290/// %35 = call i16 @llvm.bswap.i16(i16 %33)
2291/// %36 = zext i16 %34 to i64
2292/// %37 = zext i16 %35 to i64
2293/// %38 = sub i64 %36, %37
2294/// %39 = icmp ne i64 %38, 0
2295/// br i1 %39, label %res_block, label %loadbb3
2296/// loadbb3: ; preds = %loadbb2
2297/// %40 = bitcast i32* %buffer2 to i8*
2298/// %41 = bitcast i32* %buffer1 to i8*
2299/// %42 = getelementptr i8, i8* %41, i8 14
2300/// %43 = getelementptr i8, i8* %40, i8 14
2301/// %44 = load i8, i8* %42
2302/// %45 = load i8, i8* %43
2303/// %46 = zext i8 %44 to i32
2304/// %47 = zext i8 %45 to i32
2305/// %48 = sub i32 %46, %47
2306/// br label %endblock
2307/// endblock: ; preds = %res_block,
2308/// %loadbb3
2309/// %phi.res = phi i32 [ %48, %loadbb3 ], [ %11, %res_block ]
2310/// ret i32 %phi.res
2311static bool expandMemCmp(CallInst *CI, const TargetTransformInfo *TTI,
2312 const TargetLowering *TLI, const DataLayout *DL) {
2313 NumMemCmpCalls++;
2314
2315 // TTI call to check if target would like to expand memcmp. Also, get the
2316 // MaxLoadSize.
2317 unsigned MaxLoadSize;
2318 if (!TTI->enableMemCmpExpansion(MaxLoadSize))
2319 return false;
2320
2321 // Early exit from expansion if -Oz.
2322 if (CI->getFunction()->optForMinSize())
2323 return false;
2324
2325 // Early exit from expansion if size is not a constant.
2326 ConstantInt *SizeCast = dyn_cast<ConstantInt>(CI->getArgOperand(2));
2327 if (!SizeCast) {
2328 NumMemCmpNotConstant++;
2329 return false;
2330 }
2331
2332 // Scale the max size down if the target can load more bytes than we need.
2333 uint64_t SizeVal = SizeCast->getZExtValue();
2334 if (MaxLoadSize > SizeVal)
2335 MaxLoadSize = 1 << SizeCast->getValue().logBase2();
2336
2337 // Calculate how many load pairs are needed for the constant size.
2338 unsigned NumLoads = 0;
2339 unsigned RemainingSize = SizeVal;
2340 unsigned LoadSize = MaxLoadSize;
2341 while (RemainingSize) {
2342 NumLoads += RemainingSize / LoadSize;
2343 RemainingSize = RemainingSize % LoadSize;
2344 LoadSize = LoadSize / 2;
2345 }
2346
2347 // Don't expand if this will require more loads than desired by the target.
2348 if (NumLoads > TLI->getMaxExpandSizeMemcmp(CI->getFunction()->optForSize())) {
2349 NumMemCmpGreaterThanMax++;
2350 return false;
2351 }
2352
2353 NumMemCmpInlined++;
2354
2355 // MemCmpHelper object creates and sets up basic blocks required for
2356 // expanding memcmp with size SizeVal.
2357 unsigned NumLoadsPerBlock = MemCmpNumLoadsPerBlock;
2358 MemCmpExpansion MemCmpHelper(CI, SizeVal, MaxLoadSize, NumLoadsPerBlock, *DL);
2359
2360 Value *Res = MemCmpHelper.getMemCmpExpansion(SizeVal);
2361
2362 // Replace call with result of expansion and erase call.
2363 CI->replaceAllUsesWith(Res);
2364 CI->eraseFromParent();
2365
2366 return true;
2367}
2368
2369bool CodeGenPrepare::optimizeCallInst(CallInst *CI, bool &ModifiedDT) {
2370 BasicBlock *BB = CI->getParent();
2371
2372 // Lower inline assembly if we can.
2373 // If we found an inline asm expession, and if the target knows how to
2374 // lower it to normal LLVM code, do so now.
2375 if (TLI && isa<InlineAsm>(CI->getCalledValue())) {
2376 if (TLI->ExpandInlineAsm(CI)) {
2377 // Avoid invalidating the iterator.
2378 CurInstIterator = BB->begin();
2379 // Avoid processing instructions out of order, which could cause
2380 // reuse before a value is defined.
2381 SunkAddrs.clear();
2382 return true;
2383 }
2384 // Sink address computing for memory operands into the block.
2385 if (optimizeInlineAsmInst(CI))
2386 return true;
2387 }
2388
2389 // Align the pointer arguments to this call if the target thinks it's a good
2390 // idea
2391 unsigned MinSize, PrefAlign;
2392 if (TLI && TLI->shouldAlignPointerArgs(CI, MinSize, PrefAlign)) {
2393 for (auto &Arg : CI->arg_operands()) {
2394 // We want to align both objects whose address is used directly and
2395 // objects whose address is used in casts and GEPs, though it only makes
2396 // sense for GEPs if the offset is a multiple of the desired alignment and
2397 // if size - offset meets the size threshold.
2398 if (!Arg->getType()->isPointerTy())
2399 continue;
2400 APInt Offset(DL->getPointerSizeInBits(
2401 cast<PointerType>(Arg->getType())->getAddressSpace()),
2402 0);
2403 Value *Val = Arg->stripAndAccumulateInBoundsConstantOffsets(*DL, Offset);
2404 uint64_t Offset2 = Offset.getLimitedValue();
2405 if ((Offset2 & (PrefAlign-1)) != 0)
2406 continue;
2407 AllocaInst *AI;
2408 if ((AI = dyn_cast<AllocaInst>(Val)) && AI->getAlignment() < PrefAlign &&
2409 DL->getTypeAllocSize(AI->getAllocatedType()) >= MinSize + Offset2)
2410 AI->setAlignment(PrefAlign);
2411 // Global variables can only be aligned if they are defined in this
2412 // object (i.e. they are uniquely initialized in this object), and
2413 // over-aligning global variables that have an explicit section is
2414 // forbidden.
2415 GlobalVariable *GV;
2416 if ((GV = dyn_cast<GlobalVariable>(Val)) && GV->canIncreaseAlignment() &&
2417 GV->getPointerAlignment(*DL) < PrefAlign &&
2418 DL->getTypeAllocSize(GV->getValueType()) >=
2419 MinSize + Offset2)
2420 GV->setAlignment(PrefAlign);
2421 }
2422 // If this is a memcpy (or similar) then we may be able to improve the
2423 // alignment
2424 if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(CI)) {
2425 unsigned Align = getKnownAlignment(MI->getDest(), *DL);
2426 if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(MI))
2427 Align = std::min(Align, getKnownAlignment(MTI->getSource(), *DL));
2428 if (Align > MI->getAlignment())
2429 MI->setAlignment(ConstantInt::get(MI->getAlignmentType(), Align));
2430 }
2431 }
2432
2433 // If we have a cold call site, try to sink addressing computation into the
2434 // cold block. This interacts with our handling for loads and stores to
2435 // ensure that we can fold all uses of a potential addressing computation
2436 // into their uses. TODO: generalize this to work over profiling data
2437 if (!OptSize && CI->hasFnAttr(Attribute::Cold))
2438 for (auto &Arg : CI->arg_operands()) {
2439 if (!Arg->getType()->isPointerTy())
2440 continue;
2441 unsigned AS = Arg->getType()->getPointerAddressSpace();
2442 return optimizeMemoryInst(CI, Arg, Arg->getType(), AS);
2443 }
2444
2445 IntrinsicInst *II = dyn_cast<IntrinsicInst>(CI);
2446 if (II) {
2447 switch (II->getIntrinsicID()) {
2448 default: break;
2449 case Intrinsic::objectsize: {
2450 // Lower all uses of llvm.objectsize.*
2451 ConstantInt *RetVal =
2452 lowerObjectSizeCall(II, *DL, TLInfo, /*MustSucceed=*/true);
2453 // Substituting this can cause recursive simplifications, which can
2454 // invalidate our iterator. Use a WeakTrackingVH to hold onto it in case
2455 // this
2456 // happens.
2457 Value *CurValue = &*CurInstIterator;
2458 WeakTrackingVH IterHandle(CurValue);
2459
2460 replaceAndRecursivelySimplify(CI, RetVal, TLInfo, nullptr);
2461
2462 // If the iterator instruction was recursively deleted, start over at the
2463 // start of the block.
2464 if (IterHandle != CurValue) {
2465 CurInstIterator = BB->begin();
2466 SunkAddrs.clear();
2467 }
2468 return true;
2469 }
2470 case Intrinsic::aarch64_stlxr:
2471 case Intrinsic::aarch64_stxr: {
2472 ZExtInst *ExtVal = dyn_cast<ZExtInst>(CI->getArgOperand(0));
2473 if (!ExtVal || !ExtVal->hasOneUse() ||
2474 ExtVal->getParent() == CI->getParent())
2475 return false;
2476 // Sink a zext feeding stlxr/stxr before it, so it can be folded into it.
2477 ExtVal->moveBefore(CI);
2478 // Mark this instruction as "inserted by CGP", so that other
2479 // optimizations don't touch it.
2480 InsertedInsts.insert(ExtVal);
2481 return true;
2482 }
2483 case Intrinsic::invariant_group_barrier:
2484 II->replaceAllUsesWith(II->getArgOperand(0));
2485 II->eraseFromParent();
2486 return true;
2487
2488 case Intrinsic::cttz:
2489 case Intrinsic::ctlz:
2490 // If counting zeros is expensive, try to avoid it.
2491 return despeculateCountZeros(II, TLI, DL, ModifiedDT);
2492 }
2493
2494 if (TLI) {
2495 SmallVector<Value*, 2> PtrOps;
2496 Type *AccessTy;
2497 if (TLI->getAddrModeArguments(II, PtrOps, AccessTy))
2498 while (!PtrOps.empty()) {
2499 Value *PtrVal = PtrOps.pop_back_val();
2500 unsigned AS = PtrVal->getType()->getPointerAddressSpace();
2501 if (optimizeMemoryInst(II, PtrVal, AccessTy, AS))
2502 return true;
2503 }
2504 }
2505 }
2506
2507 // From here on out we're working with named functions.
2508 if (!CI->getCalledFunction()) return false;
2509
2510 // Lower all default uses of _chk calls. This is very similar
2511 // to what InstCombineCalls does, but here we are only lowering calls
2512 // to fortified library functions (e.g. __memcpy_chk) that have the default
2513 // "don't know" as the objectsize. Anything else should be left alone.
2514 FortifiedLibCallSimplifier Simplifier(TLInfo, true);
2515 if (Value *V = Simplifier.optimizeCall(CI)) {
2516 CI->replaceAllUsesWith(V);
2517 CI->eraseFromParent();
2518 return true;
2519 }
2520
2521 LibFunc Func;
2522 if (TLInfo->getLibFunc(ImmutableCallSite(CI), Func) &&
2523 Func == LibFunc_memcmp && expandMemCmp(CI, TTI, TLI, DL)) {
2524 ModifiedDT = true;
2525 return true;
2526 }
2527 return false;
2528}
2529
2530/// Look for opportunities to duplicate return instructions to the predecessor
2531/// to enable tail call optimizations. The case it is currently looking for is:
2532/// @code
2533/// bb0:
2534/// %tmp0 = tail call i32 @f0()
2535/// br label %return
2536/// bb1:
2537/// %tmp1 = tail call i32 @f1()
2538/// br label %return
2539/// bb2:
2540/// %tmp2 = tail call i32 @f2()
2541/// br label %return
2542/// return:
2543/// %retval = phi i32 [ %tmp0, %bb0 ], [ %tmp1, %bb1 ], [ %tmp2, %bb2 ]
2544/// ret i32 %retval
2545/// @endcode
2546///
2547/// =>
2548///
2549/// @code
2550/// bb0:
2551/// %tmp0 = tail call i32 @f0()
2552/// ret i32 %tmp0
2553/// bb1:
2554/// %tmp1 = tail call i32 @f1()
2555/// ret i32 %tmp1
2556/// bb2:
2557/// %tmp2 = tail call i32 @f2()
2558/// ret i32 %tmp2
2559/// @endcode
2560bool CodeGenPrepare::dupRetToEnableTailCallOpts(BasicBlock *BB) {
2561 if (!TLI)
2562 return false;
2563
2564 ReturnInst *RetI = dyn_cast<ReturnInst>(BB->getTerminator());
2565 if (!RetI)
2566 return false;
2567
2568 PHINode *PN = nullptr;
2569 BitCastInst *BCI = nullptr;
2570 Value *V = RetI->getReturnValue();
2571 if (V) {
2572 BCI = dyn_cast<BitCastInst>(V);
2573 if (BCI)
2574 V = BCI->getOperand(0);
2575
2576 PN = dyn_cast<PHINode>(V);
2577 if (!PN)
2578 return false;
2579 }
2580
2581 if (PN && PN->getParent() != BB)
2582 return false;
2583
2584 // Make sure there are no instructions between the PHI and return, or that the
2585 // return is the first instruction in the block.
2586 if (PN) {
2587 BasicBlock::iterator BI = BB->begin();
2588 do { ++BI; } while (isa<DbgInfoIntrinsic>(BI));
2589 if (&*BI == BCI)
2590 // Also skip over the bitcast.
2591 ++BI;
2592 if (&*BI != RetI)
2593 return false;
2594 } else {
2595 BasicBlock::iterator BI = BB->begin();
2596 while (isa<DbgInfoIntrinsic>(BI)) ++BI;
2597 if (&*BI != RetI)
2598 return false;
2599 }
2600
2601 /// Only dup the ReturnInst if the CallInst is likely to be emitted as a tail
2602 /// call.
2603 const Function *F = BB->getParent();
2604 SmallVector<CallInst*, 4> TailCalls;
2605 if (PN) {
2606 for (unsigned I = 0, E = PN->getNumIncomingValues(); I != E; ++I) {
2607 CallInst *CI = dyn_cast<CallInst>(PN->getIncomingValue(I));
2608 // Make sure the phi value is indeed produced by the tail call.
2609 if (CI && CI->hasOneUse() && CI->getParent() == PN->getIncomingBlock(I) &&
2610 TLI->mayBeEmittedAsTailCall(CI) &&
2611 attributesPermitTailCall(F, CI, RetI, *TLI))
2612 TailCalls.push_back(CI);
2613 }
2614 } else {
2615 SmallPtrSet<BasicBlock*, 4> VisitedBBs;
2616 for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB); PI != PE; ++PI) {
2617 if (!VisitedBBs.insert(*PI).second)
2618 continue;
2619
2620 BasicBlock::InstListType &InstList = (*PI)->getInstList();
2621 BasicBlock::InstListType::reverse_iterator RI = InstList.rbegin();
2622 BasicBlock::InstListType::reverse_iterator RE = InstList.rend();
2623 do { ++RI; } while (RI != RE && isa<DbgInfoIntrinsic>(&*RI));
2624 if (RI == RE)
2625 continue;
2626
2627 CallInst *CI = dyn_cast<CallInst>(&*RI);
2628 if (CI && CI->use_empty() && TLI->mayBeEmittedAsTailCall(CI) &&
2629 attributesPermitTailCall(F, CI, RetI, *TLI))
2630 TailCalls.push_back(CI);
2631 }
2632 }
2633
2634 bool Changed = false;
2635 for (unsigned i = 0, e = TailCalls.size(); i != e; ++i) {
2636 CallInst *CI = TailCalls[i];
2637 CallSite CS(CI);
2638
2639 // Conservatively require the attributes of the call to match those of the
2640 // return. Ignore noalias because it doesn't affect the call sequence.
2641 AttributeList CalleeAttrs = CS.getAttributes();
2642 if (AttrBuilder(CalleeAttrs, AttributeList::ReturnIndex)
2643 .removeAttribute(Attribute::NoAlias) !=
2644 AttrBuilder(CalleeAttrs, AttributeList::ReturnIndex)
2645 .removeAttribute(Attribute::NoAlias))
2646 continue;
2647
2648 // Make sure the call instruction is followed by an unconditional branch to
2649 // the return block.
2650 BasicBlock *CallBB = CI->getParent();
2651 BranchInst *BI = dyn_cast<BranchInst>(CallBB->getTerminator());
2652 if (!BI || !BI->isUnconditional() || BI->getSuccessor(0) != BB)
2653 continue;
2654
2655 // Duplicate the return into CallBB.
2656 (void)FoldReturnIntoUncondBranch(RetI, BB, CallBB);
2657 ModifiedDT = Changed = true;
2658 ++NumRetsDup;
2659 }
2660
2661 // If we eliminated all predecessors of the block, delete the block now.
2662 if (Changed && !BB->hasAddressTaken() && pred_begin(BB) == pred_end(BB))
2663 BB->eraseFromParent();
2664
2665 return Changed;
2666}
2667
2668//===----------------------------------------------------------------------===//
2669// Memory Optimization
2670//===----------------------------------------------------------------------===//
2671
2672namespace {
2673
2674/// This is an extended version of TargetLowering::AddrMode
2675/// which holds actual Value*'s for register values.
2676struct ExtAddrMode : public TargetLowering::AddrMode {
2677 Value *BaseReg = nullptr;
2678 Value *ScaledReg = nullptr;
2679 Value *OriginalValue = nullptr;
2680
2681 enum FieldName {
2682 NoField = 0x00,
2683 BaseRegField = 0x01,
2684 BaseGVField = 0x02,
2685 BaseOffsField = 0x04,
2686 ScaledRegField = 0x08,
2687 ScaleField = 0x10,
2688 MultipleFields = 0xff
2689 };
2690
2691 ExtAddrMode() = default;
2692
2693 void print(raw_ostream &OS) const;
2694 void dump() const;
2695
2696 FieldName compare(const ExtAddrMode &other) {
2697 // First check that the types are the same on each field, as differing types
2698 // is something we can't cope with later on.
2699 if (BaseReg && other.BaseReg &&
2700 BaseReg->getType() != other.BaseReg->getType())
2701 return MultipleFields;
2702 if (BaseGV && other.BaseGV &&
2703 BaseGV->getType() != other.BaseGV->getType())
2704 return MultipleFields;
2705 if (ScaledReg && other.ScaledReg &&
2706 ScaledReg->getType() != other.ScaledReg->getType())
2707 return MultipleFields;
2708
2709 // Check each field to see if it differs.
2710 unsigned Result = NoField;
2711 if (BaseReg != other.BaseReg)
2712 Result |= BaseRegField;
2713 if (BaseGV != other.BaseGV)
2714 Result |= BaseGVField;
2715 if (BaseOffs != other.BaseOffs)
2716 Result |= BaseOffsField;
2717 if (ScaledReg != other.ScaledReg)
2718 Result |= ScaledRegField;
2719 // Don't count 0 as being a different scale, because that actually means
2720 // unscaled (which will already be counted by having no ScaledReg).
2721 if (Scale && other.Scale && Scale != other.Scale)
2722 Result |= ScaleField;
2723
2724 if (countPopulation(Result) > 1)
2725 return MultipleFields;
2726 else
2727 return static_cast<FieldName>(Result);
2728 }
2729
2730 // AddrModes with a base reg or gv where the reg/gv is just the original
2731 // value are trivial.
2732 bool isTrivial() {
2733 bool Trivial = (BaseGV && BaseGV == OriginalValue) ||
2734 (BaseReg && BaseReg == OriginalValue);
2735 // If the AddrMode is trivial it shouldn't have an offset or be scaled.
2736 if (Trivial) {
2737 assert(BaseOffs == 0)((BaseOffs == 0) ? static_cast<void> (0) : __assert_fail
("BaseOffs == 0", "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 2737, __PRETTY_FUNCTION__))
;
2738 assert(Scale == 0)((Scale == 0) ? static_cast<void> (0) : __assert_fail (
"Scale == 0", "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 2738, __PRETTY_FUNCTION__))
;
2739 }
2740 return Trivial;
2741 }
2742};
2743
2744} // end anonymous namespace
2745
2746#ifndef NDEBUG
2747static inline raw_ostream &operator<<(raw_ostream &OS, const ExtAddrMode &AM) {
2748 AM.print(OS);
2749 return OS;
2750}
2751#endif
2752
2753#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
2754void ExtAddrMode::print(raw_ostream &OS) const {
2755 bool NeedPlus = false;
2756 OS << "[";
2757 if (BaseGV) {
2758 OS << (NeedPlus ? " + " : "")
2759 << "GV:";
2760 BaseGV->printAsOperand(OS, /*PrintType=*/false);
2761 NeedPlus = true;
2762 }
2763
2764 if (BaseOffs) {
2765 OS << (NeedPlus ? " + " : "")
2766 << BaseOffs;
2767 NeedPlus = true;
2768 }
2769
2770 if (BaseReg) {
2771 OS << (NeedPlus ? " + " : "")
2772 << "Base:";
2773 BaseReg->printAsOperand(OS, /*PrintType=*/false);
2774 NeedPlus = true;
2775 }
2776 if (Scale) {
2777 OS << (NeedPlus ? " + " : "")
2778 << Scale << "*";
2779 ScaledReg->printAsOperand(OS, /*PrintType=*/false);
2780 }
2781
2782 OS << ']';
2783}
2784
2785LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void ExtAddrMode::dump() const {
2786 print(dbgs());
2787 dbgs() << '\n';
2788}
2789#endif
2790
2791namespace {
2792
2793/// \brief This class provides transaction based operation on the IR.
2794/// Every change made through this class is recorded in the internal state and
2795/// can be undone (rollback) until commit is called.
2796class TypePromotionTransaction {
2797 /// \brief This represents the common interface of the individual transaction.
2798 /// Each class implements the logic for doing one specific modification on
2799 /// the IR via the TypePromotionTransaction.
2800 class TypePromotionAction {
2801 protected:
2802 /// The Instruction modified.
2803 Instruction *Inst;
2804
2805 public:
2806 /// \brief Constructor of the action.
2807 /// The constructor performs the related action on the IR.
2808 TypePromotionAction(Instruction *Inst) : Inst(Inst) {}
2809
2810 virtual ~TypePromotionAction() = default;
2811
2812 /// \brief Undo the modification done by this action.
2813 /// When this method is called, the IR must be in the same state as it was
2814 /// before this action was applied.
2815 /// \pre Undoing the action works if and only if the IR is in the exact same
2816 /// state as it was directly after this action was applied.
2817 virtual void undo() = 0;
2818
2819 /// \brief Advocate every change made by this action.
2820 /// When the results on the IR of the action are to be kept, it is important
2821 /// to call this function, otherwise hidden information may be kept forever.
2822 virtual void commit() {
2823 // Nothing to be done, this action is not doing anything.
2824 }
2825 };
2826
2827 /// \brief Utility to remember the position of an instruction.
2828 class InsertionHandler {
2829 /// Position of an instruction.
2830 /// Either an instruction:
2831 /// - Is the first in a basic block: BB is used.
2832 /// - Has a previous instructon: PrevInst is used.
2833 union {
2834 Instruction *PrevInst;
2835 BasicBlock *BB;
2836 } Point;
2837
2838 /// Remember whether or not the instruction had a previous instruction.
2839 bool HasPrevInstruction;
2840
2841 public:
2842 /// \brief Record the position of \p Inst.
2843 InsertionHandler(Instruction *Inst) {
2844 BasicBlock::iterator It = Inst->getIterator();
2845 HasPrevInstruction = (It != (Inst->getParent()->begin()));
2846 if (HasPrevInstruction)
2847 Point.PrevInst = &*--It;
2848 else
2849 Point.BB = Inst->getParent();
2850 }
2851
2852 /// \brief Insert \p Inst at the recorded position.
2853 void insert(Instruction *Inst) {
2854 if (HasPrevInstruction) {
2855 if (Inst->getParent())
2856 Inst->removeFromParent();
2857 Inst->insertAfter(Point.PrevInst);
2858 } else {
2859 Instruction *Position = &*Point.BB->getFirstInsertionPt();
2860 if (Inst->getParent())
2861 Inst->moveBefore(Position);
2862 else
2863 Inst->insertBefore(Position);
2864 }
2865 }
2866 };
2867
2868 /// \brief Move an instruction before another.
2869 class InstructionMoveBefore : public TypePromotionAction {
2870 /// Original position of the instruction.
2871 InsertionHandler Position;
2872
2873 public:
2874 /// \brief Move \p Inst before \p Before.
2875 InstructionMoveBefore(Instruction *Inst, Instruction *Before)
2876 : TypePromotionAction(Inst), Position(Inst) {
2877 DEBUG(dbgs() << "Do: move: " << *Inst << "\nbefore: " << *Before << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: move: " << *
Inst << "\nbefore: " << *Before << "\n"; } }
while (false)
;
2878 Inst->moveBefore(Before);
2879 }
2880
2881 /// \brief Move the instruction back to its original position.
2882 void undo() override {
2883 DEBUG(dbgs() << "Undo: moveBefore: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: moveBefore: " <<
*Inst << "\n"; } } while (false)
;
2884 Position.insert(Inst);
2885 }
2886 };
2887
2888 /// \brief Set the operand of an instruction with a new value.
2889 class OperandSetter : public TypePromotionAction {
2890 /// Original operand of the instruction.
2891 Value *Origin;
2892
2893 /// Index of the modified instruction.
2894 unsigned Idx;
2895
2896 public:
2897 /// \brief Set \p Idx operand of \p Inst with \p NewVal.
2898 OperandSetter(Instruction *Inst, unsigned Idx, Value *NewVal)
2899 : TypePromotionAction(Inst), Idx(Idx) {
2900 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)
2901 << "for:" << *Inst << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: setOperand: " <<
Idx << "\n" << "for:" << *Inst << "\n"
<< "with:" << *NewVal << "\n"; } } while (
false)
2902 << "with:" << *NewVal << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: setOperand: " <<
Idx << "\n" << "for:" << *Inst << "\n"
<< "with:" << *NewVal << "\n"; } } while (
false)
;
2903 Origin = Inst->getOperand(Idx);
2904 Inst->setOperand(Idx, NewVal);
2905 }
2906
2907 /// \brief Restore the original value of the instruction.
2908 void undo() override {
2909 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)
2910 << "for: " << *Inst << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: setOperand:" <<
Idx << "\n" << "for: " << *Inst << "\n"
<< "with: " << *Origin << "\n"; } } while (
false)
2911 << "with: " << *Origin << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: setOperand:" <<
Idx << "\n" << "for: " << *Inst << "\n"
<< "with: " << *Origin << "\n"; } } while (
false)
;
2912 Inst->setOperand(Idx, Origin);
2913 }
2914 };
2915
2916 /// \brief Hide the operands of an instruction.
2917 /// Do as if this instruction was not using any of its operands.
2918 class OperandsHider : public TypePromotionAction {
2919 /// The list of original operands.
2920 SmallVector<Value *, 4> OriginalValues;
2921
2922 public:
2923 /// \brief Remove \p Inst from the uses of the operands of \p Inst.
2924 OperandsHider(Instruction *Inst) : TypePromotionAction(Inst) {
2925 DEBUG(dbgs() << "Do: OperandsHider: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: OperandsHider: " <<
*Inst << "\n"; } } while (false)
;
2926 unsigned NumOpnds = Inst->getNumOperands();
2927 OriginalValues.reserve(NumOpnds);
2928 for (unsigned It = 0; It < NumOpnds; ++It) {
2929 // Save the current operand.
2930 Value *Val = Inst->getOperand(It);
2931 OriginalValues.push_back(Val);
2932 // Set a dummy one.
2933 // We could use OperandSetter here, but that would imply an overhead
2934 // that we are not willing to pay.
2935 Inst->setOperand(It, UndefValue::get(Val->getType()));
2936 }
2937 }
2938
2939 /// \brief Restore the original list of uses.
2940 void undo() override {
2941 DEBUG(dbgs() << "Undo: OperandsHider: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: OperandsHider: "
<< *Inst << "\n"; } } while (false)
;
2942 for (unsigned It = 0, EndIt = OriginalValues.size(); It != EndIt; ++It)
2943 Inst->setOperand(It, OriginalValues[It]);
2944 }
2945 };
2946
2947 /// \brief Build a truncate instruction.
2948 class TruncBuilder : public TypePromotionAction {
2949 Value *Val;
2950
2951 public:
2952 /// \brief Build a truncate instruction of \p Opnd producing a \p Ty
2953 /// result.
2954 /// trunc Opnd to Ty.
2955 TruncBuilder(Instruction *Opnd, Type *Ty) : TypePromotionAction(Opnd) {
2956 IRBuilder<> Builder(Opnd);
2957 Val = Builder.CreateTrunc(Opnd, Ty, "promoted");
2958 DEBUG(dbgs() << "Do: TruncBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: TruncBuilder: " <<
*Val << "\n"; } } while (false)
;
2959 }
2960
2961 /// \brief Get the built value.
2962 Value *getBuiltValue() { return Val; }
2963
2964 /// \brief Remove the built instruction.
2965 void undo() override {
2966 DEBUG(dbgs() << "Undo: TruncBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: TruncBuilder: " <<
*Val << "\n"; } } while (false)
;
2967 if (Instruction *IVal = dyn_cast<Instruction>(Val))
2968 IVal->eraseFromParent();
2969 }
2970 };
2971
2972 /// \brief Build a sign extension instruction.
2973 class SExtBuilder : public TypePromotionAction {
2974 Value *Val;
2975
2976 public:
2977 /// \brief Build a sign extension instruction of \p Opnd producing a \p Ty
2978 /// result.
2979 /// sext Opnd to Ty.
2980 SExtBuilder(Instruction *InsertPt, Value *Opnd, Type *Ty)
2981 : TypePromotionAction(InsertPt) {
2982 IRBuilder<> Builder(InsertPt);
2983 Val = Builder.CreateSExt(Opnd, Ty, "promoted");
2984 DEBUG(dbgs() << "Do: SExtBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: SExtBuilder: " <<
*Val << "\n"; } } while (false)
;
2985 }
2986
2987 /// \brief Get the built value.
2988 Value *getBuiltValue() { return Val; }
2989
2990 /// \brief Remove the built instruction.
2991 void undo() override {
2992 DEBUG(dbgs() << "Undo: SExtBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: SExtBuilder: " <<
*Val << "\n"; } } while (false)
;
2993 if (Instruction *IVal = dyn_cast<Instruction>(Val))
2994 IVal->eraseFromParent();
2995 }
2996 };
2997
2998 /// \brief Build a zero extension instruction.
2999 class ZExtBuilder : public TypePromotionAction {
3000 Value *Val;
3001
3002 public:
3003 /// \brief Build a zero extension instruction of \p Opnd producing a \p Ty
3004 /// result.
3005 /// zext Opnd to Ty.
3006 ZExtBuilder(Instruction *InsertPt, Value *Opnd, Type *Ty)
3007 : TypePromotionAction(InsertPt) {
3008 IRBuilder<> Builder(InsertPt);
3009 Val = Builder.CreateZExt(Opnd, Ty, "promoted");
3010 DEBUG(dbgs() << "Do: ZExtBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: ZExtBuilder: " <<
*Val << "\n"; } } while (false)
;
3011 }
3012
3013 /// \brief Get the built value.
3014 Value *getBuiltValue() { return Val; }
3015
3016 /// \brief Remove the built instruction.
3017 void undo() override {
3018 DEBUG(dbgs() << "Undo: ZExtBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: ZExtBuilder: " <<
*Val << "\n"; } } while (false)
;
3019 if (Instruction *IVal = dyn_cast<Instruction>(Val))
3020 IVal->eraseFromParent();
3021 }
3022 };
3023
3024 /// \brief Mutate an instruction to another type.
3025 class TypeMutator : public TypePromotionAction {
3026 /// Record the original type.
3027 Type *OrigTy;
3028
3029 public:
3030 /// \brief Mutate the type of \p Inst into \p NewTy.
3031 TypeMutator(Instruction *Inst, Type *NewTy)
3032 : TypePromotionAction(Inst), OrigTy(Inst->getType()) {
3033 DEBUG(dbgs() << "Do: MutateType: " << *Inst << " with " << *NewTydo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: MutateType: " <<
*Inst << " with " << *NewTy << "\n"; } } while
(false)
3034 << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: MutateType: " <<
*Inst << " with " << *NewTy << "\n"; } } while
(false)
;
3035 Inst->mutateType(NewTy);
3036 }
3037
3038 /// \brief Mutate the instruction back to its original type.
3039 void undo() override {
3040 DEBUG(dbgs() << "Undo: MutateType: " << *Inst << " with " << *OrigTydo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: MutateType: " <<
*Inst << " with " << *OrigTy << "\n"; } } while
(false)
3041 << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: MutateType: " <<
*Inst << " with " << *OrigTy << "\n"; } } while
(false)
;
3042 Inst->mutateType(OrigTy);
3043 }
3044 };
3045
3046 /// \brief Replace the uses of an instruction by another instruction.
3047 class UsesReplacer : public TypePromotionAction {
3048 /// Helper structure to keep track of the replaced uses.
3049 struct InstructionAndIdx {
3050 /// The instruction using the instruction.
3051 Instruction *Inst;
3052
3053 /// The index where this instruction is used for Inst.
3054 unsigned Idx;
3055
3056 InstructionAndIdx(Instruction *Inst, unsigned Idx)
3057 : Inst(Inst), Idx(Idx) {}
3058 };
3059
3060 /// Keep track of the original uses (pair Instruction, Index).
3061 SmallVector<InstructionAndIdx, 4> OriginalUses;
3062
3063 using use_iterator = SmallVectorImpl<InstructionAndIdx>::iterator;
3064
3065 public:
3066 /// \brief Replace all the use of \p Inst by \p New.
3067 UsesReplacer(Instruction *Inst, Value *New) : TypePromotionAction(Inst) {
3068 DEBUG(dbgs() << "Do: UsersReplacer: " << *Inst << " with " << *Newdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: UsersReplacer: " <<
*Inst << " with " << *New << "\n"; } } while
(false)
3069 << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: UsersReplacer: " <<
*Inst << " with " << *New << "\n"; } } while
(false)
;
3070 // Record the original uses.
3071 for (Use &U : Inst->uses()) {
3072 Instruction *UserI = cast<Instruction>(U.getUser());
3073 OriginalUses.push_back(InstructionAndIdx(UserI, U.getOperandNo()));
3074 }
3075 // Now, we can replace the uses.
3076 Inst->replaceAllUsesWith(New);
3077 }
3078
3079 /// \brief Reassign the original uses of Inst to Inst.
3080 void undo() override {
3081 DEBUG(dbgs() << "Undo: UsersReplacer: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: UsersReplacer: "
<< *Inst << "\n"; } } while (false)
;
3082 for (use_iterator UseIt = OriginalUses.begin(),
3083 EndIt = OriginalUses.end();
3084 UseIt != EndIt; ++UseIt) {
3085 UseIt->Inst->setOperand(UseIt->Idx, Inst);
3086 }
3087 }
3088 };
3089
3090 /// \brief Remove an instruction from the IR.
3091 class InstructionRemover : public TypePromotionAction {
3092 /// Original position of the instruction.
3093 InsertionHandler Inserter;
3094
3095 /// Helper structure to hide all the link to the instruction. In other
3096 /// words, this helps to do as if the instruction was removed.
3097 OperandsHider Hider;
3098
3099 /// Keep track of the uses replaced, if any.
3100 UsesReplacer *Replacer = nullptr;
3101
3102 /// Keep track of instructions removed.
3103 SetOfInstrs &RemovedInsts;
3104
3105 public:
3106 /// \brief Remove all reference of \p Inst and optinally replace all its
3107 /// uses with New.
3108 /// \p RemovedInsts Keep track of the instructions removed by this Action.
3109 /// \pre If !Inst->use_empty(), then New != nullptr
3110 InstructionRemover(Instruction *Inst, SetOfInstrs &RemovedInsts,
3111 Value *New = nullptr)
3112 : TypePromotionAction(Inst), Inserter(Inst), Hider(Inst),
3113 RemovedInsts(RemovedInsts) {
3114 if (New)
3115 Replacer = new UsesReplacer(Inst, New);
3116 DEBUG(dbgs() << "Do: InstructionRemover: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: InstructionRemover: "
<< *Inst << "\n"; } } while (false)
;
3117 RemovedInsts.insert(Inst);
3118 /// The instructions removed here will be freed after completing
3119 /// optimizeBlock() for all blocks as we need to keep track of the
3120 /// removed instructions during promotion.
3121 Inst->removeFromParent();
3122 }
3123
3124 ~InstructionRemover() override { delete Replacer; }
3125
3126 /// \brief Resurrect the instruction and reassign it to the proper uses if
3127 /// new value was provided when build this action.
3128 void undo() override {
3129 DEBUG(dbgs() << "Undo: InstructionRemover: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: InstructionRemover: "
<< *Inst << "\n"; } } while (false)
;
3130 Inserter.insert(Inst);
3131 if (Replacer)
3132 Replacer->undo();
3133 Hider.undo();
3134 RemovedInsts.erase(Inst);
3135 }
3136 };
3137
3138public:
3139 /// Restoration point.
3140 /// The restoration point is a pointer to an action instead of an iterator
3141 /// because the iterator may be invalidated but not the pointer.
3142 using ConstRestorationPt = const TypePromotionAction *;
3143
3144 TypePromotionTransaction(SetOfInstrs &RemovedInsts)
3145 : RemovedInsts(RemovedInsts) {}
3146
3147 /// Advocate every changes made in that transaction.
3148 void commit();
3149
3150 /// Undo all the changes made after the given point.
3151 void rollback(ConstRestorationPt Point);
3152
3153 /// Get the current restoration point.
3154 ConstRestorationPt getRestorationPoint() const;
3155
3156 /// \name API for IR modification with state keeping to support rollback.
3157 /// @{
3158 /// Same as Instruction::setOperand.
3159 void setOperand(Instruction *Inst, unsigned Idx, Value *NewVal);
3160
3161 /// Same as Instruction::eraseFromParent.
3162 void eraseInstruction(Instruction *Inst, Value *NewVal = nullptr);
3163
3164 /// Same as Value::replaceAllUsesWith.
3165 void replaceAllUsesWith(Instruction *Inst, Value *New);
3166
3167 /// Same as Value::mutateType.
3168 void mutateType(Instruction *Inst, Type *NewTy);
3169
3170 /// Same as IRBuilder::createTrunc.
3171 Value *createTrunc(Instruction *Opnd, Type *Ty);
3172
3173 /// Same as IRBuilder::createSExt.
3174 Value *createSExt(Instruction *Inst, Value *Opnd, Type *Ty);
3175
3176 /// Same as IRBuilder::createZExt.
3177 Value *createZExt(Instruction *Inst, Value *Opnd, Type *Ty);
3178
3179 /// Same as Instruction::moveBefore.
3180 void moveBefore(Instruction *Inst, Instruction *Before);
3181 /// @}
3182
3183private:
3184 /// The ordered list of actions made so far.
3185 SmallVector<std::unique_ptr<TypePromotionAction>, 16> Actions;
3186
3187 using CommitPt = SmallVectorImpl<std::unique_ptr<TypePromotionAction>>::iterator;
3188
3189 SetOfInstrs &RemovedInsts;
3190};
3191
3192} // end anonymous namespace
3193
3194void TypePromotionTransaction::setOperand(Instruction *Inst, unsigned Idx,
3195 Value *NewVal) {
3196 Actions.push_back(llvm::make_unique<TypePromotionTransaction::OperandSetter>(
3197 Inst, Idx, NewVal));
3198}
3199
3200void TypePromotionTransaction::eraseInstruction(Instruction *Inst,
3201 Value *NewVal) {
3202 Actions.push_back(
3203 llvm::make_unique<TypePromotionTransaction::InstructionRemover>(
3204 Inst, RemovedInsts, NewVal));
3205}
3206
3207void TypePromotionTransaction::replaceAllUsesWith(Instruction *Inst,
3208 Value *New) {
3209 Actions.push_back(
3210 llvm::make_unique<TypePromotionTransaction::UsesReplacer>(Inst, New));
3211}
3212
3213void TypePromotionTransaction::mutateType(Instruction *Inst, Type *NewTy) {
3214 Actions.push_back(
3215 llvm::make_unique<TypePromotionTransaction::TypeMutator>(Inst, NewTy));
3216}
3217
3218Value *TypePromotionTransaction::createTrunc(Instruction *Opnd,
3219 Type *Ty) {
3220 std::unique_ptr<TruncBuilder> Ptr(new TruncBuilder(Opnd, Ty));
3221 Value *Val = Ptr->getBuiltValue();
3222 Actions.push_back(std::move(Ptr));
3223 return Val;
3224}
3225
3226Value *TypePromotionTransaction::createSExt(Instruction *Inst,
3227 Value *Opnd, Type *Ty) {
3228 std::unique_ptr<SExtBuilder> Ptr(new SExtBuilder(Inst, Opnd, Ty));
3229 Value *Val = Ptr->getBuiltValue();
3230 Actions.push_back(std::move(Ptr));
3231 return Val;
3232}
3233
3234Value *TypePromotionTransaction::createZExt(Instruction *Inst,
3235 Value *Opnd, Type *Ty) {
3236 std::unique_ptr<ZExtBuilder> Ptr(new ZExtBuilder(Inst, Opnd, Ty));
3237 Value *Val = Ptr->getBuiltValue();
3238 Actions.push_back(std::move(Ptr));
3239 return Val;
3240}
3241
3242void TypePromotionTransaction::moveBefore(Instruction *Inst,
3243 Instruction *Before) {
3244 Actions.push_back(
3245 llvm::make_unique<TypePromotionTransaction::InstructionMoveBefore>(
3246 Inst, Before));
3247}
3248
3249TypePromotionTransaction::ConstRestorationPt
3250TypePromotionTransaction::getRestorationPoint() const {
3251 return !Actions.empty() ? Actions.back().get() : nullptr;
3252}
3253
3254void TypePromotionTransaction::commit() {
3255 for (CommitPt It = Actions.begin(), EndIt = Actions.end(); It != EndIt;
3256 ++It)
3257 (*It)->commit();
3258 Actions.clear();
3259}
3260
3261void TypePromotionTransaction::rollback(
3262 TypePromotionTransaction::ConstRestorationPt Point) {
3263 while (!Actions.empty() && Point != Actions.back().get()) {
3264 std::unique_ptr<TypePromotionAction> Curr = Actions.pop_back_val();
3265 Curr->undo();
3266 }
3267}
3268
3269namespace {
3270
3271/// \brief A helper class for matching addressing modes.
3272///
3273/// This encapsulates the logic for matching the target-legal addressing modes.
3274class AddressingModeMatcher {
3275 SmallVectorImpl<Instruction*> &AddrModeInsts;
3276 const TargetLowering &TLI;
3277 const TargetRegisterInfo &TRI;
3278 const DataLayout &DL;
3279
3280 /// AccessTy/MemoryInst - This is the type for the access (e.g. double) and
3281 /// the memory instruction that we're computing this address for.
3282 Type *AccessTy;
3283 unsigned AddrSpace;
3284 Instruction *MemoryInst;
3285
3286 /// This is the addressing mode that we're building up. This is
3287 /// part of the return value of this addressing mode matching stuff.
3288 ExtAddrMode &AddrMode;
3289
3290 /// The instructions inserted by other CodeGenPrepare optimizations.
3291 const SetOfInstrs &InsertedInsts;
3292
3293 /// A map from the instructions to their type before promotion.
3294 InstrToOrigTy &PromotedInsts;
3295
3296 /// The ongoing transaction where every action should be registered.
3297 TypePromotionTransaction &TPT;
3298
3299 /// This is set to true when we should not do profitability checks.
3300 /// When true, IsProfitableToFoldIntoAddressingMode always returns true.
3301 bool IgnoreProfitability;
3302
3303 AddressingModeMatcher(SmallVectorImpl<Instruction *> &AMI,
3304 const TargetLowering &TLI,
3305 const TargetRegisterInfo &TRI,
3306 Type *AT, unsigned AS,
3307 Instruction *MI, ExtAddrMode &AM,
3308 const SetOfInstrs &InsertedInsts,
3309 InstrToOrigTy &PromotedInsts,
3310 TypePromotionTransaction &TPT)
3311 : AddrModeInsts(AMI), TLI(TLI), TRI(TRI),
3312 DL(MI->getModule()->getDataLayout()), AccessTy(AT), AddrSpace(AS),
3313 MemoryInst(MI), AddrMode(AM), InsertedInsts(InsertedInsts),
3314 PromotedInsts(PromotedInsts), TPT(TPT) {
3315 IgnoreProfitability = false;
3316 }
3317
3318public:
3319 /// Find the maximal addressing mode that a load/store of V can fold,
3320 /// give an access type of AccessTy. This returns a list of involved
3321 /// instructions in AddrModeInsts.
3322 /// \p InsertedInsts The instructions inserted by other CodeGenPrepare
3323 /// optimizations.
3324 /// \p PromotedInsts maps the instructions to their type before promotion.
3325 /// \p The ongoing transaction where every action should be registered.
3326 static ExtAddrMode Match(Value *V, Type *AccessTy, unsigned AS,
3327 Instruction *MemoryInst,
3328 SmallVectorImpl<Instruction*> &AddrModeInsts,
3329 const TargetLowering &TLI,
3330 const TargetRegisterInfo &TRI,
3331 const SetOfInstrs &InsertedInsts,
3332 InstrToOrigTy &PromotedInsts,
3333 TypePromotionTransaction &TPT) {
3334 ExtAddrMode Result;
3335
3336 bool Success = AddressingModeMatcher(AddrModeInsts, TLI, TRI,
3337 AccessTy, AS,
3338 MemoryInst, Result, InsertedInsts,
3339 PromotedInsts, TPT).matchAddr(V, 0);
3340 (void)Success; assert(Success && "Couldn't select *anything*?")((Success && "Couldn't select *anything*?") ? static_cast
<void> (0) : __assert_fail ("Success && \"Couldn't select *anything*?\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 3340, __PRETTY_FUNCTION__))
;
3341 return Result;
3342 }
3343
3344private:
3345 bool matchScaledValue(Value *ScaleReg, int64_t Scale, unsigned Depth);
3346 bool matchAddr(Value *V, unsigned Depth);
3347 bool matchOperationAddr(User *Operation, unsigned Opcode, unsigned Depth,
3348 bool *MovedAway = nullptr);
3349 bool isProfitableToFoldIntoAddressingMode(Instruction *I,
3350 ExtAddrMode &AMBefore,
3351 ExtAddrMode &AMAfter);
3352 bool valueAlreadyLiveAtInst(Value *Val, Value *KnownLive1, Value *KnownLive2);
3353 bool isPromotionProfitable(unsigned NewCost, unsigned OldCost,
3354 Value *PromotedOperand) const;
3355};
3356
3357/// \brief A helper class for combining addressing modes.
3358class AddressingModeCombiner {
3359private:
3360 /// The addressing modes we've collected.
3361 SmallVector<ExtAddrMode, 16> AddrModes;
3362
3363 /// The field in which the AddrModes differ, when we have more than one.
3364 ExtAddrMode::FieldName DifferentField = ExtAddrMode::NoField;
3365
3366 /// Are the AddrModes that we have all just equal to their original values?
3367 bool AllAddrModesTrivial = true;
3368
3369public:
3370 /// \brief Get the combined AddrMode
3371 const ExtAddrMode &getAddrMode() const {
3372 return AddrModes[0];
3373 }
3374
3375 /// \brief Add a new AddrMode if it's compatible with the AddrModes we already
3376 /// have.
3377 /// \return True iff we succeeded in doing so.
3378 bool addNewAddrMode(ExtAddrMode &NewAddrMode) {
3379 // Take note of if we have any non-trivial AddrModes, as we need to detect
3380 // when all AddrModes are trivial as then we would introduce a phi or select
3381 // which just duplicates what's already there.
3382 AllAddrModesTrivial = AllAddrModesTrivial && NewAddrMode.isTrivial();
3383
3384 // If this is the first addrmode then everything is fine.
3385 if (AddrModes.empty()) {
3386 AddrModes.emplace_back(NewAddrMode);
3387 return true;
3388 }
3389
3390 // Figure out how different this is from the other address modes, which we
3391 // can do just by comparing against the first one given that we only care
3392 // about the cumulative difference.
3393 ExtAddrMode::FieldName ThisDifferentField =
3394 AddrModes[0].compare(NewAddrMode);
3395 if (DifferentField == ExtAddrMode::NoField)
3396 DifferentField = ThisDifferentField;
3397 else if (DifferentField != ThisDifferentField)
3398 DifferentField = ExtAddrMode::MultipleFields;
3399
3400 // If this AddrMode is the same as all the others then everything is fine
3401 // (which should only happen when there is actually only one AddrMode).
3402 if (DifferentField == ExtAddrMode::NoField) {
3403 assert(AddrModes.size() == 1)((AddrModes.size() == 1) ? static_cast<void> (0) : __assert_fail
("AddrModes.size() == 1", "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 3403, __PRETTY_FUNCTION__))
;
3404 return true;
3405 }
3406
3407 // If NewAddrMode differs in only one dimension then we can handle it by
3408 // inserting a phi/select later on.
3409 if (DifferentField != ExtAddrMode::MultipleFields) {
3410 AddrModes.emplace_back(NewAddrMode);
3411 return true;
3412 }
3413
3414 // We couldn't combine NewAddrMode with the rest, so return failure.
3415 AddrModes.clear();
3416 return false;
3417 }
3418
3419 /// \brief Combine the addressing modes we've collected into a single
3420 /// addressing mode.
3421 /// \return True iff we successfully combined them or we only had one so
3422 /// didn't need to combine them anyway.
3423 bool combineAddrModes() {
3424 // If we have no AddrModes then they can't be combined.
3425 if (AddrModes.size() == 0)
3426 return false;
3427
3428 // A single AddrMode can trivially be combined.
3429 if (AddrModes.size() == 1)
3430 return true;
3431
3432 // If the AddrModes we collected are all just equal to the value they are
3433 // derived from then combining them wouldn't do anything useful.
3434 if (AllAddrModesTrivial)
3435 return false;
3436
3437 // TODO: Combine multiple AddrModes by inserting a select or phi for the
3438 // field in which the AddrModes differ.
3439 return false;
3440 }
3441};
3442
3443} // end anonymous namespace
3444
3445/// Try adding ScaleReg*Scale to the current addressing mode.
3446/// Return true and update AddrMode if this addr mode is legal for the target,
3447/// false if not.
3448bool AddressingModeMatcher::matchScaledValue(Value *ScaleReg, int64_t Scale,
3449 unsigned Depth) {
3450 // If Scale is 1, then this is the same as adding ScaleReg to the addressing
3451 // mode. Just process that directly.
3452 if (Scale == 1)
3453 return matchAddr(ScaleReg, Depth);
3454
3455 // If the scale is 0, it takes nothing to add this.
3456 if (Scale == 0)
3457 return true;
3458
3459 // If we already have a scale of this value, we can add to it, otherwise, we
3460 // need an available scale field.
3461 if (AddrMode.Scale != 0 && AddrMode.ScaledReg != ScaleReg)
3462 return false;
3463
3464 ExtAddrMode TestAddrMode = AddrMode;
3465
3466 // Add scale to turn X*4+X*3 -> X*7. This could also do things like
3467 // [A+B + A*7] -> [B+A*8].
3468 TestAddrMode.Scale += Scale;
3469 TestAddrMode.ScaledReg = ScaleReg;
3470
3471 // If the new address isn't legal, bail out.
3472 if (!TLI.isLegalAddressingMode(DL, TestAddrMode, AccessTy, AddrSpace))
3473 return false;
3474
3475 // It was legal, so commit it.
3476 AddrMode = TestAddrMode;
3477
3478 // Okay, we decided that we can add ScaleReg+Scale to AddrMode. Check now
3479 // to see if ScaleReg is actually X+C. If so, we can turn this into adding
3480 // X*Scale + C*Scale to addr mode.
3481 ConstantInt *CI = nullptr; Value *AddLHS = nullptr;
3482 if (isa<Instruction>(ScaleReg) && // not a constant expr.
3483 match(ScaleReg, m_Add(m_Value(AddLHS), m_ConstantInt(CI)))) {
3484 TestAddrMode.ScaledReg = AddLHS;
3485 TestAddrMode.BaseOffs += CI->getSExtValue()*TestAddrMode.Scale;
3486
3487 // If this addressing mode is legal, commit it and remember that we folded
3488 // this instruction.
3489 if (TLI.isLegalAddressingMode(DL, TestAddrMode, AccessTy, AddrSpace)) {
3490 AddrModeInsts.push_back(cast<Instruction>(ScaleReg));
3491 AddrMode = TestAddrMode;
3492 return true;
3493 }
3494 }
3495
3496 // Otherwise, not (x+c)*scale, just return what we have.
3497 return true;
3498}
3499
3500/// This is a little filter, which returns true if an addressing computation
3501/// involving I might be folded into a load/store accessing it.
3502/// This doesn't need to be perfect, but needs to accept at least
3503/// the set of instructions that MatchOperationAddr can.
3504static bool MightBeFoldableInst(Instruction *I) {
3505 switch (I->getOpcode()) {
3506 case Instruction::BitCast:
3507 case Instruction::AddrSpaceCast:
3508 // Don't touch identity bitcasts.
3509 if (I->getType() == I->getOperand(0)->getType())
3510 return false;
3511 return I->getType()->isPointerTy() || I->getType()->isIntegerTy();
3512 case Instruction::PtrToInt:
3513 // PtrToInt is always a noop, as we know that the int type is pointer sized.
3514 return true;
3515 case Instruction::IntToPtr:
3516 // We know the input is intptr_t, so this is foldable.
3517 return true;
3518 case Instruction::Add:
3519 return true;
3520 case Instruction::Mul:
3521 case Instruction::Shl:
3522 // Can only handle X*C and X << C.
3523 return isa<ConstantInt>(I->getOperand(1));
3524 case Instruction::GetElementPtr:
3525 return true;
3526 default:
3527 return false;
3528 }
3529}
3530
3531/// \brief Check whether or not \p Val is a legal instruction for \p TLI.
3532/// \note \p Val is assumed to be the product of some type promotion.
3533/// Therefore if \p Val has an undefined state in \p TLI, this is assumed
3534/// to be legal, as the non-promoted value would have had the same state.
3535static bool isPromotedInstructionLegal(const TargetLowering &TLI,
3536 const DataLayout &DL, Value *Val) {
3537 Instruction *PromotedInst = dyn_cast<Instruction>(Val);
3538 if (!PromotedInst)
3539 return false;
3540 int ISDOpcode = TLI.InstructionOpcodeToISD(PromotedInst->getOpcode());
3541 // If the ISDOpcode is undefined, it was undefined before the promotion.
3542 if (!ISDOpcode)
3543 return true;
3544 // Otherwise, check if the promoted instruction is legal or not.
3545 return TLI.isOperationLegalOrCustom(
3546 ISDOpcode, TLI.getValueType(DL, PromotedInst->getType()));
3547}
3548
3549namespace {
3550
3551/// \brief Hepler class to perform type promotion.
3552class TypePromotionHelper {
3553 /// \brief Utility function to check whether or not a sign or zero extension
3554 /// of \p Inst with \p ConsideredExtType can be moved through \p Inst by
3555 /// either using the operands of \p Inst or promoting \p Inst.
3556 /// The type of the extension is defined by \p IsSExt.
3557 /// In other words, check if:
3558 /// ext (Ty Inst opnd1 opnd2 ... opndN) to ConsideredExtType.
3559 /// #1 Promotion applies:
3560 /// ConsideredExtType Inst (ext opnd1 to ConsideredExtType, ...).
3561 /// #2 Operand reuses:
3562 /// ext opnd1 to ConsideredExtType.
3563 /// \p PromotedInsts maps the instructions to their type before promotion.
3564 static bool canGetThrough(const Instruction *Inst, Type *ConsideredExtType,
3565 const InstrToOrigTy &PromotedInsts, bool IsSExt);
3566
3567 /// \brief Utility function to determine if \p OpIdx should be promoted when
3568 /// promoting \p Inst.
3569 static bool shouldExtOperand(const Instruction *Inst, int OpIdx) {
3570 return !(isa<SelectInst>(Inst) && OpIdx == 0);
3571 }
3572
3573 /// \brief Utility function to promote the operand of \p Ext when this
3574 /// operand is a promotable trunc or sext or zext.
3575 /// \p PromotedInsts maps the instructions to their type before promotion.
3576 /// \p CreatedInstsCost[out] contains the cost of all instructions
3577 /// created to promote the operand of Ext.
3578 /// Newly added extensions are inserted in \p Exts.
3579 /// Newly added truncates are inserted in \p Truncs.
3580 /// Should never be called directly.
3581 /// \return The promoted value which is used instead of Ext.
3582 static Value *promoteOperandForTruncAndAnyExt(
3583 Instruction *Ext, TypePromotionTransaction &TPT,
3584 InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
3585 SmallVectorImpl<Instruction *> *Exts,
3586 SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI);
3587
3588 /// \brief Utility function to promote the operand of \p Ext when this
3589 /// operand is promotable and is not a supported trunc or sext.
3590 /// \p PromotedInsts maps the instructions to their type before promotion.
3591 /// \p CreatedInstsCost[out] contains the cost of all the instructions
3592 /// created to promote the operand of Ext.
3593 /// Newly added extensions are inserted in \p Exts.
3594 /// Newly added truncates are inserted in \p Truncs.
3595 /// Should never be called directly.
3596 /// \return The promoted value which is used instead of Ext.
3597 static Value *promoteOperandForOther(Instruction *Ext,
3598 TypePromotionTransaction &TPT,
3599 InstrToOrigTy &PromotedInsts,
3600 unsigned &CreatedInstsCost,
3601 SmallVectorImpl<Instruction *> *Exts,
3602 SmallVectorImpl<Instruction *> *Truncs,
3603 const TargetLowering &TLI, bool IsSExt);
3604
3605 /// \see promoteOperandForOther.
3606 static Value *signExtendOperandForOther(
3607 Instruction *Ext, TypePromotionTransaction &TPT,
3608 InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
3609 SmallVectorImpl<Instruction *> *Exts,
3610 SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI) {
3611 return promoteOperandForOther(Ext, TPT, PromotedInsts, CreatedInstsCost,
3612 Exts, Truncs, TLI, true);
3613 }
3614
3615 /// \see promoteOperandForOther.
3616 static Value *zeroExtendOperandForOther(
3617 Instruction *Ext, TypePromotionTransaction &TPT,
3618 InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
3619 SmallVectorImpl<Instruction *> *Exts,
3620 SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI) {
3621 return promoteOperandForOther(Ext, TPT, PromotedInsts, CreatedInstsCost,
3622 Exts, Truncs, TLI, false);
3623 }
3624
3625public:
3626 /// Type for the utility function that promotes the operand of Ext.
3627 using Action = Value *(*)(Instruction *Ext, TypePromotionTransaction &TPT,
3628 InstrToOrigTy &PromotedInsts,
3629 unsigned &CreatedInstsCost,
3630 SmallVectorImpl<Instruction *> *Exts,
3631 SmallVectorImpl<Instruction *> *Truncs,
3632 const TargetLowering &TLI);
3633
3634 /// \brief Given a sign/zero extend instruction \p Ext, return the approriate
3635 /// action to promote the operand of \p Ext instead of using Ext.
3636 /// \return NULL if no promotable action is possible with the current
3637 /// sign extension.
3638 /// \p InsertedInsts keeps track of all the instructions inserted by the
3639 /// other CodeGenPrepare optimizations. This information is important
3640 /// because we do not want to promote these instructions as CodeGenPrepare
3641 /// will reinsert them later. Thus creating an infinite loop: create/remove.
3642 /// \p PromotedInsts maps the instructions to their type before promotion.
3643 static Action getAction(Instruction *Ext, const SetOfInstrs &InsertedInsts,
3644 const TargetLowering &TLI,
3645 const InstrToOrigTy &PromotedInsts);
3646};
3647
3648} // end anonymous namespace
3649
3650bool TypePromotionHelper::canGetThrough(const Instruction *Inst,
3651 Type *ConsideredExtType,
3652 const InstrToOrigTy &PromotedInsts,
3653 bool IsSExt) {
3654 // The promotion helper does not know how to deal with vector types yet.
3655 // To be able to fix that, we would need to fix the places where we
3656 // statically extend, e.g., constants and such.
3657 if (Inst->getType()->isVectorTy())
3658 return false;
3659
3660 // We can always get through zext.
3661 if (isa<ZExtInst>(Inst))
3662 return true;
3663
3664 // sext(sext) is ok too.
3665 if (IsSExt && isa<SExtInst>(Inst))
3666 return true;
3667
3668 // We can get through binary operator, if it is legal. In other words, the
3669 // binary operator must have a nuw or nsw flag.
3670 const BinaryOperator *BinOp = dyn_cast<BinaryOperator>(Inst);
3671 if (BinOp && isa<OverflowingBinaryOperator>(BinOp) &&
3672 ((!IsSExt && BinOp->hasNoUnsignedWrap()) ||
3673 (IsSExt && BinOp->hasNoSignedWrap())))
3674 return true;
3675
3676 // Check if we can do the following simplification.
3677 // ext(trunc(opnd)) --> ext(opnd)
3678 if (!isa<TruncInst>(Inst))
3679 return false;
3680
3681 Value *OpndVal = Inst->getOperand(0);
3682 // Check if we can use this operand in the extension.
3683 // If the type is larger than the result type of the extension, we cannot.
3684 if (!OpndVal->getType()->isIntegerTy() ||
3685 OpndVal->getType()->getIntegerBitWidth() >
3686 ConsideredExtType->getIntegerBitWidth())
3687 return false;
3688
3689 // If the operand of the truncate is not an instruction, we will not have
3690 // any information on the dropped bits.
3691 // (Actually we could for constant but it is not worth the extra logic).
3692 Instruction *Opnd = dyn_cast<Instruction>(OpndVal);
3693 if (!Opnd)
3694 return false;
3695
3696 // Check if the source of the type is narrow enough.
3697 // I.e., check that trunc just drops extended bits of the same kind of
3698 // the extension.
3699 // #1 get the type of the operand and check the kind of the extended bits.
3700 const Type *OpndType;
3701 InstrToOrigTy::const_iterator It = PromotedInsts.find(Opnd);
3702 if (It != PromotedInsts.end() && It->second.getInt() == IsSExt)
3703 OpndType = It->second.getPointer();
3704 else if ((IsSExt && isa<SExtInst>(Opnd)) || (!IsSExt && isa<ZExtInst>(Opnd)))
3705 OpndType = Opnd->getOperand(0)->getType();
3706 else
3707 return false;
3708
3709 // #2 check that the truncate just drops extended bits.
3710 return Inst->getType()->getIntegerBitWidth() >=
3711 OpndType->getIntegerBitWidth();
3712}
3713
3714TypePromotionHelper::Action TypePromotionHelper::getAction(
3715 Instruction *Ext, const SetOfInstrs &InsertedInsts,
3716 const TargetLowering &TLI, const InstrToOrigTy &PromotedInsts) {
3717 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\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 3718, __PRETTY_FUNCTION__))
3718 "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\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 3718, __PRETTY_FUNCTION__))
;
3719 Instruction *ExtOpnd = dyn_cast<Instruction>(Ext->getOperand(0));
3720 Type *ExtTy = Ext->getType();
3721 bool IsSExt = isa<SExtInst>(Ext);
3722 // If the operand of the extension is not an instruction, we cannot
3723 // get through.
3724 // If it, check we can get through.
3725 if (!ExtOpnd || !canGetThrough(ExtOpnd, ExtTy, PromotedInsts, IsSExt))
3726 return nullptr;
3727
3728 // Do not promote if the operand has been added by codegenprepare.
3729 // Otherwise, it means we are undoing an optimization that is likely to be
3730 // redone, thus causing potential infinite loop.
3731 if (isa<TruncInst>(ExtOpnd) && InsertedInsts.count(ExtOpnd))
3732 return nullptr;
3733
3734 // SExt or Trunc instructions.
3735 // Return the related handler.
3736 if (isa<SExtInst>(ExtOpnd) || isa<TruncInst>(ExtOpnd) ||
3737 isa<ZExtInst>(ExtOpnd))
3738 return promoteOperandForTruncAndAnyExt;
3739
3740 // Regular instruction.
3741 // Abort early if we will have to insert non-free instructions.
3742 if (!ExtOpnd->hasOneUse() && !TLI.isTruncateFree(ExtTy, ExtOpnd->getType()))
3743 return nullptr;
3744 return IsSExt ? signExtendOperandForOther : zeroExtendOperandForOther;
3745}
3746
3747Value *TypePromotionHelper::promoteOperandForTruncAndAnyExt(
3748 Instruction *SExt, TypePromotionTransaction &TPT,
3749 InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
3750 SmallVectorImpl<Instruction *> *Exts,
3751 SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI) {
3752 // By construction, the operand of SExt is an instruction. Otherwise we cannot
3753 // get through it and this method should not be called.
3754 Instruction *SExtOpnd = cast<Instruction>(SExt->getOperand(0));
3755 Value *ExtVal = SExt;
3756 bool HasMergedNonFreeExt = false;
3757 if (isa<ZExtInst>(SExtOpnd)) {
3758 // Replace s|zext(zext(opnd))
3759 // => zext(opnd).
3760 HasMergedNonFreeExt = !TLI.isExtFree(SExtOpnd);
3761 Value *ZExt =
3762 TPT.createZExt(SExt, SExtOpnd->getOperand(0), SExt->getType());
3763 TPT.replaceAllUsesWith(SExt, ZExt);
3764 TPT.eraseInstruction(SExt);
3765 ExtVal = ZExt;
3766 } else {
3767 // Replace z|sext(trunc(opnd)) or sext(sext(opnd))
3768 // => z|sext(opnd).
3769 TPT.setOperand(SExt, 0, SExtOpnd->getOperand(0));
3770 }
3771 CreatedInstsCost = 0;
3772
3773 // Remove dead code.
3774 if (SExtOpnd->use_empty())
3775 TPT.eraseInstruction(SExtOpnd);
3776
3777 // Check if the extension is still needed.
3778 Instruction *ExtInst = dyn_cast<Instruction>(ExtVal);
3779 if (!ExtInst || ExtInst->getType() != ExtInst->getOperand(0)->getType()) {
3780 if (ExtInst) {
3781 if (Exts)
3782 Exts->push_back(ExtInst);
3783 CreatedInstsCost = !TLI.isExtFree(ExtInst) && !HasMergedNonFreeExt;
3784 }
3785 return ExtVal;
3786 }
3787
3788 // At this point we have: ext ty opnd to ty.
3789 // Reassign the uses of ExtInst to the opnd and remove ExtInst.
3790 Value *NextVal = ExtInst->getOperand(0);
3791 TPT.eraseInstruction(ExtInst, NextVal);
3792 return NextVal;
3793}
3794
3795Value *TypePromotionHelper::promoteOperandForOther(
3796 Instruction *Ext, TypePromotionTransaction &TPT,
3797 InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
3798 SmallVectorImpl<Instruction *> *Exts,
3799 SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI,
3800 bool IsSExt) {
3801 // By construction, the operand of Ext is an instruction. Otherwise we cannot
3802 // get through it and this method should not be called.
3803 Instruction *ExtOpnd = cast<Instruction>(Ext->getOperand(0));
3804 CreatedInstsCost = 0;
3805 if (!ExtOpnd->hasOneUse()) {
3806 // ExtOpnd will be promoted.
3807 // All its uses, but Ext, will need to use a truncated value of the
3808 // promoted version.
3809 // Create the truncate now.
3810 Value *Trunc = TPT.createTrunc(Ext, ExtOpnd->getType());
3811 if (Instruction *ITrunc = dyn_cast<Instruction>(Trunc)) {
3812 // Insert it just after the definition.
3813 ITrunc->moveAfter(ExtOpnd);
3814 if (Truncs)
3815 Truncs->push_back(ITrunc);
3816 }
3817
3818 TPT.replaceAllUsesWith(ExtOpnd, Trunc);
3819 // Restore the operand of Ext (which has been replaced by the previous call
3820 // to replaceAllUsesWith) to avoid creating a cycle trunc <-> sext.
3821 TPT.setOperand(Ext, 0, ExtOpnd);
3822 }
3823
3824 // Get through the Instruction:
3825 // 1. Update its type.
3826 // 2. Replace the uses of Ext by Inst.
3827 // 3. Extend each operand that needs to be extended.
3828
3829 // Remember the original type of the instruction before promotion.
3830 // This is useful to know that the high bits are sign extended bits.
3831 PromotedInsts.insert(std::pair<Instruction *, TypeIsSExt>(
3832 ExtOpnd, TypeIsSExt(ExtOpnd->getType(), IsSExt)));
3833 // Step #1.
3834 TPT.mutateType(ExtOpnd, Ext->getType());
3835 // Step #2.
3836 TPT.replaceAllUsesWith(Ext, ExtOpnd);
3837 // Step #3.
3838 Instruction *ExtForOpnd = Ext;
3839
3840 DEBUG(dbgs() << "Propagate Ext to operands\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Propagate Ext to operands\n"
; } } while (false)
;
3841 for (int OpIdx = 0, EndOpIdx = ExtOpnd->getNumOperands(); OpIdx != EndOpIdx;
3842 ++OpIdx) {
3843 DEBUG(dbgs() << "Operand:\n" << *(ExtOpnd->getOperand(OpIdx)) << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Operand:\n" << *
(ExtOpnd->getOperand(OpIdx)) << '\n'; } } while (false
)
;
3844 if (ExtOpnd->getOperand(OpIdx)->getType() == Ext->getType() ||
3845 !shouldExtOperand(ExtOpnd, OpIdx)) {
3846 DEBUG(dbgs() << "No need to propagate\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "No need to propagate\n"
; } } while (false)
;
3847 continue;
3848 }
3849 // Check if we can statically extend the operand.
3850 Value *Opnd = ExtOpnd->getOperand(OpIdx);
3851 if (const ConstantInt *Cst = dyn_cast<ConstantInt>(Opnd)) {
3852 DEBUG(dbgs() << "Statically extend\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Statically extend\n"; }
} while (false)
;
3853 unsigned BitWidth = Ext->getType()->getIntegerBitWidth();
3854 APInt CstVal = IsSExt ? Cst->getValue().sext(BitWidth)
3855 : Cst->getValue().zext(BitWidth);
3856 TPT.setOperand(ExtOpnd, OpIdx, ConstantInt::get(Ext->getType(), CstVal));
3857 continue;
3858 }
3859 // UndefValue are typed, so we have to statically sign extend them.
3860 if (isa<UndefValue>(Opnd)) {
3861 DEBUG(dbgs() << "Statically extend\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Statically extend\n"; }
} while (false)
;
3862 TPT.setOperand(ExtOpnd, OpIdx, UndefValue::get(Ext->getType()));
3863 continue;
3864 }
3865
3866 // Otherwise we have to explicity sign extend the operand.
3867 // Check if Ext was reused to extend an operand.
3868 if (!ExtForOpnd) {
3869 // If yes, create a new one.
3870 DEBUG(dbgs() << "More operands to ext\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "More operands to ext\n"
; } } while (false)
;
3871 Value *ValForExtOpnd = IsSExt ? TPT.createSExt(Ext, Opnd, Ext->getType())
3872 : TPT.createZExt(Ext, Opnd, Ext->getType());
3873 if (!isa<Instruction>(ValForExtOpnd)) {
3874 TPT.setOperand(ExtOpnd, OpIdx, ValForExtOpnd);
3875 continue;
3876 }
3877 ExtForOpnd = cast<Instruction>(ValForExtOpnd);
3878 }
3879 if (Exts)
3880 Exts->push_back(ExtForOpnd);
3881 TPT.setOperand(ExtForOpnd, 0, Opnd);
3882
3883 // Move the sign extension before the insertion point.
3884 TPT.moveBefore(ExtForOpnd, ExtOpnd);
3885 TPT.setOperand(ExtOpnd, OpIdx, ExtForOpnd);
3886 CreatedInstsCost += !TLI.isExtFree(ExtForOpnd);
3887 // If more sext are required, new instructions will have to be created.
3888 ExtForOpnd = nullptr;
3889 }
3890 if (ExtForOpnd == Ext) {
3891 DEBUG(dbgs() << "Extension is useless now\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Extension is useless now\n"
; } } while (false)
;
3892 TPT.eraseInstruction(Ext);
3893 }
3894 return ExtOpnd;
3895}
3896
3897/// Check whether or not promoting an instruction to a wider type is profitable.
3898/// \p NewCost gives the cost of extension instructions created by the
3899/// promotion.
3900/// \p OldCost gives the cost of extension instructions before the promotion
3901/// plus the number of instructions that have been
3902/// matched in the addressing mode the promotion.
3903/// \p PromotedOperand is the value that has been promoted.
3904/// \return True if the promotion is profitable, false otherwise.
3905bool AddressingModeMatcher::isPromotionProfitable(
3906 unsigned NewCost, unsigned OldCost, Value *PromotedOperand) const {
3907 DEBUG(dbgs() << "OldCost: " << OldCost << "\tNewCost: " << NewCost << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "OldCost: " << OldCost
<< "\tNewCost: " << NewCost << '\n'; } } while
(false)
;
3908 // The cost of the new extensions is greater than the cost of the
3909 // old extension plus what we folded.
3910 // This is not profitable.
3911 if (NewCost > OldCost)
3912 return false;
3913 if (NewCost < OldCost)
3914 return true;
3915 // The promotion is neutral but it may help folding the sign extension in
3916 // loads for instance.
3917 // Check that we did not create an illegal instruction.
3918 return isPromotedInstructionLegal(TLI, DL, PromotedOperand);
3919}
3920
3921/// Given an instruction or constant expr, see if we can fold the operation
3922/// into the addressing mode. If so, update the addressing mode and return
3923/// true, otherwise return false without modifying AddrMode.
3924/// If \p MovedAway is not NULL, it contains the information of whether or
3925/// not AddrInst has to be folded into the addressing mode on success.
3926/// If \p MovedAway == true, \p AddrInst will not be part of the addressing
3927/// because it has been moved away.
3928/// Thus AddrInst must not be added in the matched instructions.
3929/// This state can happen when AddrInst is a sext, since it may be moved away.
3930/// Therefore, AddrInst may not be valid when MovedAway is true and it must
3931/// not be referenced anymore.
3932bool AddressingModeMatcher::matchOperationAddr(User *AddrInst, unsigned Opcode,
3933 unsigned Depth,
3934 bool *MovedAway) {
3935 // Avoid exponential behavior on extremely deep expression trees.
3936 if (Depth >= 5) return false;
3937
3938 // By default, all matched instructions stay in place.
3939 if (MovedAway)
3940 *MovedAway = false;
3941
3942 switch (Opcode) {
3943 case Instruction::PtrToInt:
3944 // PtrToInt is always a noop, as we know that the int type is pointer sized.
3945 return matchAddr(AddrInst->getOperand(0), Depth);
3946 case Instruction::IntToPtr: {
3947 auto AS = AddrInst->getType()->getPointerAddressSpace();
3948 auto PtrTy = MVT::getIntegerVT(DL.getPointerSizeInBits(AS));
3949 // This inttoptr is a no-op if the integer type is pointer sized.
3950 if (TLI.getValueType(DL, AddrInst->getOperand(0)->getType()) == PtrTy)
3951 return matchAddr(AddrInst->getOperand(0), Depth);
3952 return false;
3953 }
3954 case Instruction::BitCast:
3955 // BitCast is always a noop, and we can handle it as long as it is
3956 // int->int or pointer->pointer (we don't want int<->fp or something).
3957 if ((AddrInst->getOperand(0)->getType()->isPointerTy() ||
3958 AddrInst->getOperand(0)->getType()->isIntegerTy()) &&
3959 // Don't touch identity bitcasts. These were probably put here by LSR,
3960 // and we don't want to mess around with them. Assume it knows what it
3961 // is doing.
3962 AddrInst->getOperand(0)->getType() != AddrInst->getType())
3963 return matchAddr(AddrInst->getOperand(0), Depth);
3964 return false;
3965 case Instruction::AddrSpaceCast: {
3966 unsigned SrcAS
3967 = AddrInst->getOperand(0)->getType()->getPointerAddressSpace();
3968 unsigned DestAS = AddrInst->getType()->getPointerAddressSpace();
3969 if (TLI.isNoopAddrSpaceCast(SrcAS, DestAS))
3970 return matchAddr(AddrInst->getOperand(0), Depth);
3971 return false;
3972 }
3973 case Instruction::Add: {
3974 // Check to see if we can merge in the RHS then the LHS. If so, we win.
3975 ExtAddrMode BackupAddrMode = AddrMode;
3976 unsigned OldSize = AddrModeInsts.size();
3977 // Start a transaction at this point.
3978 // The LHS may match but not the RHS.
3979 // Therefore, we need a higher level restoration point to undo partially
3980 // matched operation.
3981 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
3982 TPT.getRestorationPoint();
3983
3984 if (matchAddr(AddrInst->getOperand(1), Depth+1) &&
3985 matchAddr(AddrInst->getOperand(0), Depth+1))
3986 return true;
3987
3988 // Restore the old addr mode info.
3989 AddrMode = BackupAddrMode;
3990 AddrModeInsts.resize(OldSize);
3991 TPT.rollback(LastKnownGood);
3992
3993 // Otherwise this was over-aggressive. Try merging in the LHS then the RHS.
3994 if (matchAddr(AddrInst->getOperand(0), Depth+1) &&
3995 matchAddr(AddrInst->getOperand(1), Depth+1))
3996 return true;
3997
3998 // Otherwise we definitely can't merge the ADD in.
3999 AddrMode = BackupAddrMode;
4000 AddrModeInsts.resize(OldSize);
4001 TPT.rollback(LastKnownGood);
4002 break;
4003 }
4004 //case Instruction::Or:
4005 // TODO: We can handle "Or Val, Imm" iff this OR is equivalent to an ADD.
4006 //break;
4007 case Instruction::Mul:
4008 case Instruction::Shl: {
4009 // Can only handle X*C and X << C.
4010 ConstantInt *RHS = dyn_cast<ConstantInt>(AddrInst->getOperand(1));
4011 if (!RHS)
4012 return false;
4013 int64_t Scale = RHS->getSExtValue();
4014 if (Opcode == Instruction::Shl)
4015 Scale = 1LL << Scale;
4016
4017 return matchScaledValue(AddrInst->getOperand(0), Scale, Depth);
4018 }
4019 case Instruction::GetElementPtr: {
4020 // Scan the GEP. We check it if it contains constant offsets and at most
4021 // one variable offset.
4022 int VariableOperand = -1;
4023 unsigned VariableScale = 0;
4024
4025 int64_t ConstantOffset = 0;
4026 gep_type_iterator GTI = gep_type_begin(AddrInst);
4027 for (unsigned i = 1, e = AddrInst->getNumOperands(); i != e; ++i, ++GTI) {
4028 if (StructType *STy = GTI.getStructTypeOrNull()) {
4029 const StructLayout *SL = DL.getStructLayout(STy);
4030 unsigned Idx =
4031 cast<ConstantInt>(AddrInst->getOperand(i))->getZExtValue();
4032 ConstantOffset += SL->getElementOffset(Idx);
4033 } else {
4034 uint64_t TypeSize = DL.getTypeAllocSize(GTI.getIndexedType());
4035 if (ConstantInt *CI = dyn_cast<ConstantInt>(AddrInst->getOperand(i))) {
4036 ConstantOffset += CI->getSExtValue()*TypeSize;
4037 } else if (TypeSize) { // Scales of zero don't do anything.
4038 // We only allow one variable index at the moment.
4039 if (VariableOperand != -1)
4040 return false;
4041
4042 // Remember the variable index.
4043 VariableOperand = i;
4044 VariableScale = TypeSize;
4045 }
4046 }
4047 }
4048
4049 // A common case is for the GEP to only do a constant offset. In this case,
4050 // just add it to the disp field and check validity.
4051 if (VariableOperand == -1) {
4052 AddrMode.BaseOffs += ConstantOffset;
4053 if (ConstantOffset == 0 ||
4054 TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace)) {
4055 // Check to see if we can fold the base pointer in too.
4056 if (matchAddr(AddrInst->getOperand(0), Depth+1))
4057 return true;
4058 }
4059 AddrMode.BaseOffs -= ConstantOffset;
4060 return false;
4061 }
4062
4063 // Save the valid addressing mode in case we can't match.
4064 ExtAddrMode BackupAddrMode = AddrMode;
4065 unsigned OldSize = AddrModeInsts.size();
4066
4067 // See if the scale and offset amount is valid for this target.
4068 AddrMode.BaseOffs += ConstantOffset;
4069
4070 // Match the base operand of the GEP.
4071 if (!matchAddr(AddrInst->getOperand(0), Depth+1)) {
4072 // If it couldn't be matched, just stuff the value in a register.
4073 if (AddrMode.HasBaseReg) {
4074 AddrMode = BackupAddrMode;
4075 AddrModeInsts.resize(OldSize);
4076 return false;
4077 }
4078 AddrMode.HasBaseReg = true;
4079 AddrMode.BaseReg = AddrInst->getOperand(0);
4080 }
4081
4082 // Match the remaining variable portion of the GEP.
4083 if (!matchScaledValue(AddrInst->getOperand(VariableOperand), VariableScale,
4084 Depth)) {
4085 // If it couldn't be matched, try stuffing the base into a register
4086 // instead of matching it, and retrying the match of the scale.
4087 AddrMode = BackupAddrMode;
4088 AddrModeInsts.resize(OldSize);
4089 if (AddrMode.HasBaseReg)
4090 return false;
4091 AddrMode.HasBaseReg = true;
4092 AddrMode.BaseReg = AddrInst->getOperand(0);
4093 AddrMode.BaseOffs += ConstantOffset;
4094 if (!matchScaledValue(AddrInst->getOperand(VariableOperand),
4095 VariableScale, Depth)) {
4096 // If even that didn't work, bail.
4097 AddrMode = BackupAddrMode;
4098 AddrModeInsts.resize(OldSize);
4099 return false;
4100 }
4101 }
4102
4103 return true;
4104 }
4105 case Instruction::SExt:
4106 case Instruction::ZExt: {
4107 Instruction *Ext = dyn_cast<Instruction>(AddrInst);
4108 if (!Ext)
4109 return false;
4110
4111 // Try to move this ext out of the way of the addressing mode.
4112 // Ask for a method for doing so.
4113 TypePromotionHelper::Action TPH =
4114 TypePromotionHelper::getAction(Ext, InsertedInsts, TLI, PromotedInsts);
4115 if (!TPH)
4116 return false;
4117
4118 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
4119 TPT.getRestorationPoint();
4120 unsigned CreatedInstsCost = 0;
4121 unsigned ExtCost = !TLI.isExtFree(Ext);
4122 Value *PromotedOperand =
4123 TPH(Ext, TPT, PromotedInsts, CreatedInstsCost, nullptr, nullptr, TLI);
4124 // SExt has been moved away.
4125 // Thus either it will be rematched later in the recursive calls or it is
4126 // gone. Anyway, we must not fold it into the addressing mode at this point.
4127 // E.g.,
4128 // op = add opnd, 1
4129 // idx = ext op
4130 // addr = gep base, idx
4131 // is now:
4132 // promotedOpnd = ext opnd <- no match here
4133 // op = promoted_add promotedOpnd, 1 <- match (later in recursive calls)
4134 // addr = gep base, op <- match
4135 if (MovedAway)
4136 *MovedAway = true;
4137
4138 assert(PromotedOperand &&((PromotedOperand && "TypePromotionHelper should have filtered out those cases"
) ? static_cast<void> (0) : __assert_fail ("PromotedOperand && \"TypePromotionHelper should have filtered out those cases\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 4139, __PRETTY_FUNCTION__))
4139 "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\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 4139, __PRETTY_FUNCTION__))
;
4140
4141 ExtAddrMode BackupAddrMode = AddrMode;
4142 unsigned OldSize = AddrModeInsts.size();
4143
4144 if (!matchAddr(PromotedOperand, Depth) ||
4145 // The total of the new cost is equal to the cost of the created
4146 // instructions.
4147 // The total of the old cost is equal to the cost of the extension plus
4148 // what we have saved in the addressing mode.
4149 !isPromotionProfitable(CreatedInstsCost,
4150 ExtCost + (AddrModeInsts.size() - OldSize),
4151 PromotedOperand)) {
4152 AddrMode = BackupAddrMode;
4153 AddrModeInsts.resize(OldSize);
4154 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)
;
4155 TPT.rollback(LastKnownGood);
4156 return false;
4157 }
4158 return true;
4159 }
4160 }
4161 return false;
4162}
4163
4164/// If we can, try to add the value of 'Addr' into the current addressing mode.
4165/// If Addr can't be added to AddrMode this returns false and leaves AddrMode
4166/// unmodified. This assumes that Addr is either a pointer type or intptr_t
4167/// for the target.
4168///
4169bool AddressingModeMatcher::matchAddr(Value *Addr, unsigned Depth) {
4170 // Start a transaction at this point that we will rollback if the matching
4171 // fails.
4172 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
4173 TPT.getRestorationPoint();
4174 if (ConstantInt *CI = dyn_cast<ConstantInt>(Addr)) {
4175 // Fold in immediates if legal for the target.
4176 AddrMode.BaseOffs += CI->getSExtValue();
4177 if (TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace))
4178 return true;
4179 AddrMode.BaseOffs -= CI->getSExtValue();
4180 } else if (GlobalValue *GV = dyn_cast<GlobalValue>(Addr)) {
4181 // If this is a global variable, try to fold it into the addressing mode.
4182 if (!AddrMode.BaseGV) {
4183 AddrMode.BaseGV = GV;
4184 if (TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace))
4185 return true;
4186 AddrMode.BaseGV = nullptr;
4187 }
4188 } else if (Instruction *I = dyn_cast<Instruction>(Addr)) {
4189 ExtAddrMode BackupAddrMode = AddrMode;
4190 unsigned OldSize = AddrModeInsts.size();
4191
4192 // Check to see if it is possible to fold this operation.
4193 bool MovedAway = false;
4194 if (matchOperationAddr(I, I->getOpcode(), Depth, &MovedAway)) {
4195 // This instruction may have been moved away. If so, there is nothing
4196 // to check here.
4197 if (MovedAway)
4198 return true;
4199 // Okay, it's possible to fold this. Check to see if it is actually
4200 // *profitable* to do so. We use a simple cost model to avoid increasing
4201 // register pressure too much.
4202 if (I->hasOneUse() ||
4203 isProfitableToFoldIntoAddressingMode(I, BackupAddrMode, AddrMode)) {
4204 AddrModeInsts.push_back(I);
4205 return true;
4206 }
4207
4208 // It isn't profitable to do this, roll back.
4209 //cerr << "NOT FOLDING: " << *I;
4210 AddrMode = BackupAddrMode;
4211 AddrModeInsts.resize(OldSize);
4212 TPT.rollback(LastKnownGood);
4213 }
4214 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Addr)) {
4215 if (matchOperationAddr(CE, CE->getOpcode(), Depth))
4216 return true;
4217 TPT.rollback(LastKnownGood);
4218 } else if (isa<ConstantPointerNull>(Addr)) {
4219 // Null pointer gets folded without affecting the addressing mode.
4220 return true;
4221 }
4222
4223 // Worse case, the target should support [reg] addressing modes. :)
4224 if (!AddrMode.HasBaseReg) {
4225 AddrMode.HasBaseReg = true;
4226 AddrMode.BaseReg = Addr;
4227 // Still check for legality in case the target supports [imm] but not [i+r].
4228 if (TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace))
4229 return true;
4230 AddrMode.HasBaseReg = false;
4231 AddrMode.BaseReg = nullptr;
4232 }
4233
4234 // If the base register is already taken, see if we can do [r+r].
4235 if (AddrMode.Scale == 0) {
4236 AddrMode.Scale = 1;
4237 AddrMode.ScaledReg = Addr;
4238 if (TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace))
4239 return true;
4240 AddrMode.Scale = 0;
4241 AddrMode.ScaledReg = nullptr;
4242 }
4243 // Couldn't match.
4244 TPT.rollback(LastKnownGood);
4245 return false;
4246}
4247
4248/// Check to see if all uses of OpVal by the specified inline asm call are due
4249/// to memory operands. If so, return true, otherwise return false.
4250static bool IsOperandAMemoryOperand(CallInst *CI, InlineAsm *IA, Value *OpVal,
4251 const TargetLowering &TLI,
4252 const TargetRegisterInfo &TRI) {
4253 const Function *F = CI->getFunction();
4254 TargetLowering::AsmOperandInfoVector TargetConstraints =
4255 TLI.ParseConstraints(F->getParent()->getDataLayout(), &TRI,
4256 ImmutableCallSite(CI));
4257
4258 for (unsigned i = 0, e = TargetConstraints.size(); i != e; ++i) {
4259 TargetLowering::AsmOperandInfo &OpInfo = TargetConstraints[i];
4260
4261 // Compute the constraint code and ConstraintType to use.
4262 TLI.ComputeConstraintToUse(OpInfo, SDValue());
4263
4264 // If this asm operand is our Value*, and if it isn't an indirect memory
4265 // operand, we can't fold it!
4266 if (OpInfo.CallOperandVal == OpVal &&
4267 (OpInfo.ConstraintType != TargetLowering::C_Memory ||
4268 !OpInfo.isIndirect))
4269 return false;
4270 }
4271
4272 return true;
4273}
4274
4275// Max number of memory uses to look at before aborting the search to conserve
4276// compile time.
4277static constexpr int MaxMemoryUsesToScan = 20;
4278
4279/// Recursively walk all the uses of I until we find a memory use.
4280/// If we find an obviously non-foldable instruction, return true.
4281/// Add the ultimately found memory instructions to MemoryUses.
4282static bool FindAllMemoryUses(
4283 Instruction *I,
4284 SmallVectorImpl<std::pair<Instruction *, unsigned>> &MemoryUses,
4285 SmallPtrSetImpl<Instruction *> &ConsideredInsts, const TargetLowering &TLI,
4286 const TargetRegisterInfo &TRI, int SeenInsts = 0) {
4287 // If we already considered this instruction, we're done.
4288 if (!ConsideredInsts.insert(I).second)
4289 return false;
4290
4291 // If this is an obviously unfoldable instruction, bail out.
4292 if (!MightBeFoldableInst(I))
4293 return true;
4294
4295 const bool OptSize = I->getFunction()->optForSize();
4296
4297 // Loop over all the uses, recursively processing them.
4298 for (Use &U : I->uses()) {
4299 // Conservatively return true if we're seeing a large number or a deep chain
4300 // of users. This avoids excessive compilation times in pathological cases.
4301 if (SeenInsts++ >= MaxMemoryUsesToScan)
4302 return true;
4303
4304 Instruction *UserI = cast<Instruction>(U.getUser());
4305 if (LoadInst *LI = dyn_cast<LoadInst>(UserI)) {
4306 MemoryUses.push_back(std::make_pair(LI, U.getOperandNo()));
4307 continue;
4308 }
4309
4310 if (StoreInst *SI = dyn_cast<StoreInst>(UserI)) {
4311 unsigned opNo = U.getOperandNo();
4312 if (opNo != StoreInst::getPointerOperandIndex())
4313 return true; // Storing addr, not into addr.
4314 MemoryUses.push_back(std::make_pair(SI, opNo));
4315 continue;
4316 }
4317
4318 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(UserI)) {
4319 unsigned opNo = U.getOperandNo();
4320 if (opNo != AtomicRMWInst::getPointerOperandIndex())
4321 return true; // Storing addr, not into addr.
4322 MemoryUses.push_back(std::make_pair(RMW, opNo));
4323 continue;
4324 }
4325
4326 if (AtomicCmpXchgInst *CmpX = dyn_cast<AtomicCmpXchgInst>(UserI)) {
4327 unsigned opNo = U.getOperandNo();
4328 if (opNo != AtomicCmpXchgInst::getPointerOperandIndex())
4329 return true; // Storing addr, not into addr.
4330 MemoryUses.push_back(std::make_pair(CmpX, opNo));
4331 continue;
4332 }
4333
4334 if (CallInst *CI = dyn_cast<CallInst>(UserI)) {
4335 // If this is a cold call, we can sink the addressing calculation into
4336 // the cold path. See optimizeCallInst
4337 if (!OptSize && CI->hasFnAttr(Attribute::Cold))
4338 continue;
4339
4340 InlineAsm *IA = dyn_cast<InlineAsm>(CI->getCalledValue());
4341 if (!IA) return true;
4342
4343 // If this is a memory operand, we're cool, otherwise bail out.
4344 if (!IsOperandAMemoryOperand(CI, IA, I, TLI, TRI))
4345 return true;
4346 continue;
4347 }
4348
4349 if (FindAllMemoryUses(UserI, MemoryUses, ConsideredInsts, TLI, TRI,
4350 SeenInsts))
4351 return true;
4352 }
4353
4354 return false;
4355}
4356
4357/// Return true if Val is already known to be live at the use site that we're
4358/// folding it into. If so, there is no cost to include it in the addressing
4359/// mode. KnownLive1 and KnownLive2 are two values that we know are live at the
4360/// instruction already.
4361bool AddressingModeMatcher::valueAlreadyLiveAtInst(Value *Val,Value *KnownLive1,
4362 Value *KnownLive2) {
4363 // If Val is either of the known-live values, we know it is live!
4364 if (Val == nullptr || Val == KnownLive1 || Val == KnownLive2)
4365 return true;
4366
4367 // All values other than instructions and arguments (e.g. constants) are live.
4368 if (!isa<Instruction>(Val) && !isa<Argument>(Val)) return true;
4369
4370 // If Val is a constant sized alloca in the entry block, it is live, this is
4371 // true because it is just a reference to the stack/frame pointer, which is
4372 // live for the whole function.
4373 if (AllocaInst *AI = dyn_cast<AllocaInst>(Val))
4374 if (AI->isStaticAlloca())
4375 return true;
4376
4377 // Check to see if this value is already used in the memory instruction's
4378 // block. If so, it's already live into the block at the very least, so we
4379 // can reasonably fold it.
4380 return Val->isUsedInBasicBlock(MemoryInst->getParent());
4381}
4382
4383/// It is possible for the addressing mode of the machine to fold the specified
4384/// instruction into a load or store that ultimately uses it.
4385/// However, the specified instruction has multiple uses.
4386/// Given this, it may actually increase register pressure to fold it
4387/// into the load. For example, consider this code:
4388///
4389/// X = ...
4390/// Y = X+1
4391/// use(Y) -> nonload/store
4392/// Z = Y+1
4393/// load Z
4394///
4395/// In this case, Y has multiple uses, and can be folded into the load of Z
4396/// (yielding load [X+2]). However, doing this will cause both "X" and "X+1" to
4397/// be live at the use(Y) line. If we don't fold Y into load Z, we use one
4398/// fewer register. Since Y can't be folded into "use(Y)" we don't increase the
4399/// number of computations either.
4400///
4401/// Note that this (like most of CodeGenPrepare) is just a rough heuristic. If
4402/// X was live across 'load Z' for other reasons, we actually *would* want to
4403/// fold the addressing mode in the Z case. This would make Y die earlier.
4404bool AddressingModeMatcher::
4405isProfitableToFoldIntoAddressingMode(Instruction *I, ExtAddrMode &AMBefore,
4406 ExtAddrMode &AMAfter) {
4407 if (IgnoreProfitability) return true;
4408
4409 // AMBefore is the addressing mode before this instruction was folded into it,
4410 // and AMAfter is the addressing mode after the instruction was folded. Get
4411 // the set of registers referenced by AMAfter and subtract out those
4412 // referenced by AMBefore: this is the set of values which folding in this
4413 // address extends the lifetime of.
4414 //
4415 // Note that there are only two potential values being referenced here,
4416 // BaseReg and ScaleReg (global addresses are always available, as are any
4417 // folded immediates).
4418 Value *BaseReg = AMAfter.BaseReg, *ScaledReg = AMAfter.ScaledReg;
4419
4420 // If the BaseReg or ScaledReg was referenced by the previous addrmode, their
4421 // lifetime wasn't extended by adding this instruction.
4422 if (valueAlreadyLiveAtInst(BaseReg, AMBefore.BaseReg, AMBefore.ScaledReg))
4423 BaseReg = nullptr;
4424 if (valueAlreadyLiveAtInst(ScaledReg, AMBefore.BaseReg, AMBefore.ScaledReg))
4425 ScaledReg = nullptr;
4426
4427 // If folding this instruction (and it's subexprs) didn't extend any live
4428 // ranges, we're ok with it.
4429 if (!BaseReg && !ScaledReg)
4430 return true;
4431
4432 // If all uses of this instruction can have the address mode sunk into them,
4433 // we can remove the addressing mode and effectively trade one live register
4434 // for another (at worst.) In this context, folding an addressing mode into
4435 // the use is just a particularly nice way of sinking it.
4436 SmallVector<std::pair<Instruction*,unsigned>, 16> MemoryUses;
4437 SmallPtrSet<Instruction*, 16> ConsideredInsts;
4438 if (FindAllMemoryUses(I, MemoryUses, ConsideredInsts, TLI, TRI))
4439 return false; // Has a non-memory, non-foldable use!
4440
4441 // Now that we know that all uses of this instruction are part of a chain of
4442 // computation involving only operations that could theoretically be folded
4443 // into a memory use, loop over each of these memory operation uses and see
4444 // if they could *actually* fold the instruction. The assumption is that
4445 // addressing modes are cheap and that duplicating the computation involved
4446 // many times is worthwhile, even on a fastpath. For sinking candidates
4447 // (i.e. cold call sites), this serves as a way to prevent excessive code
4448 // growth since most architectures have some reasonable small and fast way to
4449 // compute an effective address. (i.e LEA on x86)
4450 SmallVector<Instruction*, 32> MatchedAddrModeInsts;
4451 for (unsigned i = 0, e = MemoryUses.size(); i != e; ++i) {
4452 Instruction *User = MemoryUses[i].first;
4453 unsigned OpNo = MemoryUses[i].second;
4454
4455 // Get the access type of this use. If the use isn't a pointer, we don't
4456 // know what it accesses.
4457 Value *Address = User->getOperand(OpNo);
4458 PointerType *AddrTy = dyn_cast<PointerType>(Address->getType());
4459 if (!AddrTy)
4460 return false;
4461 Type *AddressAccessTy = AddrTy->getElementType();
4462 unsigned AS = AddrTy->getAddressSpace();
4463
4464 // Do a match against the root of this address, ignoring profitability. This
4465 // will tell us if the addressing mode for the memory operation will
4466 // *actually* cover the shared instruction.
4467 ExtAddrMode Result;
4468 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
4469 TPT.getRestorationPoint();
4470 AddressingModeMatcher Matcher(MatchedAddrModeInsts, TLI, TRI,
4471 AddressAccessTy, AS,
4472 MemoryInst, Result, InsertedInsts,
4473 PromotedInsts, TPT);
4474 Matcher.IgnoreProfitability = true;
4475 bool Success = Matcher.matchAddr(Address, 0);
4476 (void)Success; assert(Success && "Couldn't select *anything*?")((Success && "Couldn't select *anything*?") ? static_cast
<void> (0) : __assert_fail ("Success && \"Couldn't select *anything*?\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 4476, __PRETTY_FUNCTION__))
;
4477
4478 // The match was to check the profitability, the changes made are not
4479 // part of the original matcher. Therefore, they should be dropped
4480 // otherwise the original matcher will not present the right state.
4481 TPT.rollback(LastKnownGood);
4482
4483 // If the match didn't cover I, then it won't be shared by it.
4484 if (!is_contained(MatchedAddrModeInsts, I))
4485 return false;
4486
4487 MatchedAddrModeInsts.clear();
4488 }
4489
4490 return true;
4491}
4492
4493/// Return true if the specified values are defined in a
4494/// different basic block than BB.
4495static bool IsNonLocalValue(Value *V, BasicBlock *BB) {
4496 if (Instruction *I = dyn_cast<Instruction>(V))
4497 return I->getParent() != BB;
4498 return false;
4499}
4500
4501/// Sink addressing mode computation immediate before MemoryInst if doing so
4502/// can be done without increasing register pressure. The need for the
4503/// register pressure constraint means this can end up being an all or nothing
4504/// decision for all uses of the same addressing computation.
4505///
4506/// Load and Store Instructions often have addressing modes that can do
4507/// significant amounts of computation. As such, instruction selection will try
4508/// to get the load or store to do as much computation as possible for the
4509/// program. The problem is that isel can only see within a single block. As
4510/// such, we sink as much legal addressing mode work into the block as possible.
4511///
4512/// This method is used to optimize both load/store and inline asms with memory
4513/// operands. It's also used to sink addressing computations feeding into cold
4514/// call sites into their (cold) basic block.
4515///
4516/// The motivation for handling sinking into cold blocks is that doing so can
4517/// both enable other address mode sinking (by satisfying the register pressure
4518/// constraint above), and reduce register pressure globally (by removing the
4519/// addressing mode computation from the fast path entirely.).
4520bool CodeGenPrepare::optimizeMemoryInst(Instruction *MemoryInst, Value *Addr,
4521 Type *AccessTy, unsigned AddrSpace) {
4522 Value *Repl = Addr;
4523
4524 // Try to collapse single-value PHI nodes. This is necessary to undo
4525 // unprofitable PRE transformations.
4526 SmallVector<Value*, 8> worklist;
4527 SmallPtrSet<Value*, 16> Visited;
4528 worklist.push_back(Addr);
4529
4530 // Use a worklist to iteratively look through PHI and select nodes, and
4531 // ensure that the addressing mode obtained from the non-PHI/select roots of
4532 // the graph are compatible.
4533 bool PhiOrSelectSeen = false;
4534 SmallVector<Instruction*, 16> AddrModeInsts;
4535 AddressingModeCombiner AddrModes;
4536 TypePromotionTransaction TPT(RemovedInsts);
4537 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
4538 TPT.getRestorationPoint();
4539 while (!worklist.empty()) {
4540 Value *V = worklist.back();
4541 worklist.pop_back();
4542
4543 // We allow traversing cyclic Phi nodes.
4544 // In case of success after this loop we ensure that traversing through
4545 // Phi nodes ends up with all cases to compute address of the form
4546 // BaseGV + Base + Scale * Index + Offset
4547 // where Scale and Offset are constans and BaseGV, Base and Index
4548 // are exactly the same Values in all cases.
4549 // It means that BaseGV, Scale and Offset dominate our memory instruction
4550 // and have the same value as they had in address computation represented
4551 // as Phi. So we can safely sink address computation to memory instruction.
4552 if (!Visited.insert(V).second)
4553 continue;
4554
4555 // For a PHI node, push all of its incoming values.
4556 if (PHINode *P = dyn_cast<PHINode>(V)) {
4557 for (Value *IncValue : P->incoming_values())
4558 worklist.push_back(IncValue);
4559 PhiOrSelectSeen = true;
4560 continue;
4561 }
4562 // Similar for select.
4563 if (SelectInst *SI = dyn_cast<SelectInst>(V)) {
4564 worklist.push_back(SI->getFalseValue());
4565 worklist.push_back(SI->getTrueValue());
4566 PhiOrSelectSeen = true;
4567 continue;
4568 }
4569
4570 // For non-PHIs, determine the addressing mode being computed. Note that
4571 // the result may differ depending on what other uses our candidate
4572 // addressing instructions might have.
4573 AddrModeInsts.clear();
4574 ExtAddrMode NewAddrMode = AddressingModeMatcher::Match(
4575 V, AccessTy, AddrSpace, MemoryInst, AddrModeInsts, *TLI, *TRI,
4576 InsertedInsts, PromotedInsts, TPT);
4577 NewAddrMode.OriginalValue = V;
4578
4579 if (!AddrModes.addNewAddrMode(NewAddrMode))
4580 break;
4581 }
4582
4583 // Try to combine the AddrModes we've collected. If we couldn't collect any,
4584 // or we have multiple but either couldn't combine them or combining them
4585 // wouldn't do anything useful, bail out now.
4586 if (!AddrModes.combineAddrModes()) {
4587 TPT.rollback(LastKnownGood);
4588 return false;
4589 }
4590 TPT.commit();
4591
4592 // Get the combined AddrMode (or the only AddrMode, if we only had one).
4593 ExtAddrMode AddrMode = AddrModes.getAddrMode();
4594
4595 // If all the instructions matched are already in this BB, don't do anything.
4596 // If we saw a Phi node then it is not local definitely, and if we saw a select
4597 // then we want to push the address calculation past it even if it's already
4598 // in this BB.
4599 if (!PhiOrSelectSeen && none_of(AddrModeInsts, [&](Value *V) {
4600 return IsNonLocalValue(V, MemoryInst->getParent());
4601 })) {
4602 DEBUG(dbgs() << "CGP: Found local addrmode: " << AddrMode << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: Found local addrmode: "
<< AddrMode << "\n"; } } while (false)
;
4603 return false;
4604 }
4605
4606 // Insert this computation right after this user. Since our caller is
4607 // scanning from the top of the BB to the bottom, reuse of the expr are
4608 // guaranteed to happen later.
4609 IRBuilder<> Builder(MemoryInst);
4610
4611 // Now that we determined the addressing expression we want to use and know
4612 // that we have to sink it into this block. Check to see if we have already
4613 // done this for some other load/store instr in this block. If so, reuse the
4614 // computation.
4615 Value *&SunkAddr = SunkAddrs[Addr];
4616 if (SunkAddr) {
4617 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)
4618 << *MemoryInst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: Reusing nonlocal addrmode: "
<< AddrMode << " for " << *MemoryInst <<
"\n"; } } while (false)
;
4619 if (SunkAddr->getType() != Addr->getType())
4620 SunkAddr = Builder.CreatePointerCast(SunkAddr, Addr->getType());
4621 } else if (AddrSinkUsingGEPs ||
4622 (!AddrSinkUsingGEPs.getNumOccurrences() && TM &&
4623 SubtargetInfo->useAA())) {
4624 // By default, we use the GEP-based method when AA is used later. This
4625 // prevents new inttoptr/ptrtoint pairs from degrading AA capabilities.
4626 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)
4627 << *MemoryInst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: SINKING nonlocal addrmode: "
<< AddrMode << " for " << *MemoryInst <<
"\n"; } } while (false)
;
4628 Type *IntPtrTy = DL->getIntPtrType(Addr->getType());
4629 Value *ResultPtr = nullptr, *ResultIndex = nullptr;
4630
4631 // First, find the pointer.
4632 if (AddrMode.BaseReg && AddrMode.BaseReg->getType()->isPointerTy()) {
4633 ResultPtr = AddrMode.BaseReg;
4634 AddrMode.BaseReg = nullptr;
4635 }
4636
4637 if (AddrMode.Scale && AddrMode.ScaledReg->getType()->isPointerTy()) {
4638 // We can't add more than one pointer together, nor can we scale a
4639 // pointer (both of which seem meaningless).
4640 if (ResultPtr || AddrMode.Scale != 1)
4641 return false;
4642
4643 ResultPtr = AddrMode.ScaledReg;
4644 AddrMode.Scale = 0;
4645 }
4646
4647 // It is only safe to sign extend the BaseReg if we know that the math
4648 // required to create it did not overflow before we extend it. Since
4649 // the original IR value was tossed in favor of a constant back when
4650 // the AddrMode was created we need to bail out gracefully if widths
4651 // do not match instead of extending it.
4652 //
4653 // (See below for code to add the scale.)
4654 if (AddrMode.Scale) {
4655 Type *ScaledRegTy = AddrMode.ScaledReg->getType();
4656 if (cast<IntegerType>(IntPtrTy)->getBitWidth() >
4657 cast<IntegerType>(ScaledRegTy)->getBitWidth())
4658 return false;
4659 }
4660
4661 if (AddrMode.BaseGV) {
4662 if (ResultPtr)
4663 return false;
4664
4665 ResultPtr = AddrMode.BaseGV;
4666 }
4667
4668 // If the real base value actually came from an inttoptr, then the matcher
4669 // will look through it and provide only the integer value. In that case,
4670 // use it here.
4671 if (!DL->isNonIntegralPointerType(Addr->getType())) {
4672 if (!ResultPtr && AddrMode.BaseReg) {
4673 ResultPtr = Builder.CreateIntToPtr(AddrMode.BaseReg, Addr->getType(),
4674 "sunkaddr");
4675 AddrMode.BaseReg = nullptr;
4676 } else if (!ResultPtr && AddrMode.Scale == 1) {
4677 ResultPtr = Builder.CreateIntToPtr(AddrMode.ScaledReg, Addr->getType(),
4678 "sunkaddr");
4679 AddrMode.Scale = 0;
4680 }
4681 }
4682
4683 if (!ResultPtr &&
4684 !AddrMode.BaseReg && !AddrMode.Scale && !AddrMode.BaseOffs) {
4685 SunkAddr = Constant::getNullValue(Addr->getType());
4686 } else if (!ResultPtr) {
4687 return false;
4688 } else {
4689 Type *I8PtrTy =
4690 Builder.getInt8PtrTy(Addr->getType()->getPointerAddressSpace());
4691 Type *I8Ty = Builder.getInt8Ty();
4692
4693 // Start with the base register. Do this first so that subsequent address
4694 // matching finds it last, which will prevent it from trying to match it
4695 // as the scaled value in case it happens to be a mul. That would be
4696 // problematic if we've sunk a different mul for the scale, because then
4697 // we'd end up sinking both muls.
4698 if (AddrMode.BaseReg) {
4699 Value *V = AddrMode.BaseReg;
4700 if (V->getType() != IntPtrTy)
4701 V = Builder.CreateIntCast(V, IntPtrTy, /*isSigned=*/true, "sunkaddr");
4702
4703 ResultIndex = V;
4704 }
4705
4706 // Add the scale value.
4707 if (AddrMode.Scale) {
4708 Value *V = AddrMode.ScaledReg;
4709 if (V->getType() == IntPtrTy) {
4710 // done.
4711 } else {
4712 assert(cast<IntegerType>(IntPtrTy)->getBitWidth() <((cast<IntegerType>(IntPtrTy)->getBitWidth() < cast
<IntegerType>(V->getType())->getBitWidth() &&
"We can't transform if ScaledReg is too narrow") ? static_cast
<void> (0) : __assert_fail ("cast<IntegerType>(IntPtrTy)->getBitWidth() < cast<IntegerType>(V->getType())->getBitWidth() && \"We can't transform if ScaledReg is too narrow\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 4714, __PRETTY_FUNCTION__))
4713 cast<IntegerType>(V->getType())->getBitWidth() &&((cast<IntegerType>(IntPtrTy)->getBitWidth() < cast
<IntegerType>(V->getType())->getBitWidth() &&
"We can't transform if ScaledReg is too narrow") ? static_cast
<void> (0) : __assert_fail ("cast<IntegerType>(IntPtrTy)->getBitWidth() < cast<IntegerType>(V->getType())->getBitWidth() && \"We can't transform if ScaledReg is too narrow\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 4714, __PRETTY_FUNCTION__))
4714 "We can't transform if ScaledReg is too narrow")((cast<IntegerType>(IntPtrTy)->getBitWidth() < cast
<IntegerType>(V->getType())->getBitWidth() &&
"We can't transform if ScaledReg is too narrow") ? static_cast
<void> (0) : __assert_fail ("cast<IntegerType>(IntPtrTy)->getBitWidth() < cast<IntegerType>(V->getType())->getBitWidth() && \"We can't transform if ScaledReg is too narrow\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 4714, __PRETTY_FUNCTION__))
;
4715 V = Builder.CreateTrunc(V, IntPtrTy, "sunkaddr");
4716 }
4717
4718 if (AddrMode.Scale != 1)
4719 V = Builder.CreateMul(V, ConstantInt::get(IntPtrTy, AddrMode.Scale),
4720 "sunkaddr");
4721 if (ResultIndex)
4722 ResultIndex = Builder.CreateAdd(ResultIndex, V, "sunkaddr");
4723 else
4724 ResultIndex = V;
4725 }
4726
4727 // Add in the Base Offset if present.
4728 if (AddrMode.BaseOffs) {
4729 Value *V = ConstantInt::get(IntPtrTy, AddrMode.BaseOffs);
4730 if (ResultIndex) {
4731 // We need to add this separately from the scale above to help with
4732 // SDAG consecutive load/store merging.
4733 if (ResultPtr->getType() != I8PtrTy)
4734 ResultPtr = Builder.CreatePointerCast(ResultPtr, I8PtrTy);
4735 ResultPtr = Builder.CreateGEP(I8Ty, ResultPtr, ResultIndex, "sunkaddr");
4736 }
4737
4738 ResultIndex = V;
4739 }
4740
4741 if (!ResultIndex) {
4742 SunkAddr = ResultPtr;
4743 } else {
4744 if (ResultPtr->getType() != I8PtrTy)
4745 ResultPtr = Builder.CreatePointerCast(ResultPtr, I8PtrTy);
4746 SunkAddr = Builder.CreateGEP(I8Ty, ResultPtr, ResultIndex, "sunkaddr");
4747 }
4748
4749 if (SunkAddr->getType() != Addr->getType())
4750 SunkAddr = Builder.CreatePointerCast(SunkAddr, Addr->getType());
4751 }
4752 } else {
4753 // We'd require a ptrtoint/inttoptr down the line, which we can't do for
4754 // non-integral pointers, so in that case bail out now.
4755 Type *BaseTy = AddrMode.BaseReg ? AddrMode.BaseReg->getType() : nullptr;
4756 Type *ScaleTy = AddrMode.Scale ? AddrMode.ScaledReg->getType() : nullptr;
4757 PointerType *BasePtrTy = dyn_cast_or_null<PointerType>(BaseTy);
4758 PointerType *ScalePtrTy = dyn_cast_or_null<PointerType>(ScaleTy);
4759 if (DL->isNonIntegralPointerType(Addr->getType()) ||
4760 (BasePtrTy && DL->isNonIntegralPointerType(BasePtrTy)) ||
4761 (ScalePtrTy && DL->isNonIntegralPointerType(ScalePtrTy)) ||
4762 (AddrMode.BaseGV &&
4763 DL->isNonIntegralPointerType(AddrMode.BaseGV->getType())))
4764 return false;
4765
4766 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)
4767 << *MemoryInst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: SINKING nonlocal addrmode: "
<< AddrMode << " for " << *MemoryInst <<
"\n"; } } while (false)
;
4768 Type *IntPtrTy = DL->getIntPtrType(Addr->getType());
4769 Value *Result = nullptr;
4770
4771 // Start with the base register. Do this first so that subsequent address
4772 // matching finds it last, which will prevent it from trying to match it
4773 // as the scaled value in case it happens to be a mul. That would be
4774 // problematic if we've sunk a different mul for the scale, because then
4775 // we'd end up sinking both muls.
4776 if (AddrMode.BaseReg) {
4777 Value *V = AddrMode.BaseReg;
4778 if (V->getType()->isPointerTy())
4779 V = Builder.CreatePtrToInt(V, IntPtrTy, "sunkaddr");
4780 if (V->getType() != IntPtrTy)
4781 V = Builder.CreateIntCast(V, IntPtrTy, /*isSigned=*/true, "sunkaddr");
4782 Result = V;
4783 }
4784
4785 // Add the scale value.
4786 if (AddrMode.Scale) {
4787 Value *V = AddrMode.ScaledReg;
4788 if (V->getType() == IntPtrTy) {
4789 // done.
4790 } else if (V->getType()->isPointerTy()) {
4791 V = Builder.CreatePtrToInt(V, IntPtrTy, "sunkaddr");
4792 } else if (cast<IntegerType>(IntPtrTy)->getBitWidth() <
4793 cast<IntegerType>(V->getType())->getBitWidth()) {
4794 V = Builder.CreateTrunc(V, IntPtrTy, "sunkaddr");
4795 } else {
4796 // It is only safe to sign extend the BaseReg if we know that the math
4797 // required to create it did not overflow before we extend it. Since
4798 // the original IR value was tossed in favor of a constant back when
4799 // the AddrMode was created we need to bail out gracefully if widths
4800 // do not match instead of extending it.
4801 Instruction *I = dyn_cast_or_null<Instruction>(Result);
4802 if (I && (Result != AddrMode.BaseReg))
4803 I->eraseFromParent();
4804 return false;
4805 }
4806 if (AddrMode.Scale != 1)
4807 V = Builder.CreateMul(V, ConstantInt::get(IntPtrTy, AddrMode.Scale),
4808 "sunkaddr");
4809 if (Result)
4810 Result = Builder.CreateAdd(Result, V, "sunkaddr");
4811 else
4812 Result = V;
4813 }
4814
4815 // Add in the BaseGV if present.
4816 if (AddrMode.BaseGV) {
4817 Value *V = Builder.CreatePtrToInt(AddrMode.BaseGV, IntPtrTy, "sunkaddr");
4818 if (Result)
4819 Result = Builder.CreateAdd(Result, V, "sunkaddr");
4820 else
4821 Result = V;
4822 }
4823
4824 // Add in the Base Offset if present.
4825 if (AddrMode.BaseOffs) {
4826 Value *V = ConstantInt::get(IntPtrTy, AddrMode.BaseOffs);
4827 if (Result)
4828 Result = Builder.CreateAdd(Result, V, "sunkaddr");
4829 else
4830 Result = V;
4831 }
4832
4833 if (!Result)
4834 SunkAddr = Constant::getNullValue(Addr->getType());
4835 else
4836 SunkAddr = Builder.CreateIntToPtr(Result, Addr->getType(), "sunkaddr");
4837 }
4838
4839 MemoryInst->replaceUsesOfWith(Repl, SunkAddr);
4840
4841 // If we have no uses, recursively delete the value and all dead instructions
4842 // using it.
4843 if (Repl->use_empty()) {
4844 // This can cause recursive deletion, which can invalidate our iterator.
4845 // Use a WeakTrackingVH to hold onto it in case this happens.
4846 Value *CurValue = &*CurInstIterator;
4847 WeakTrackingVH IterHandle(CurValue);
4848 BasicBlock *BB = CurInstIterator->getParent();
4849
4850 RecursivelyDeleteTriviallyDeadInstructions(Repl, TLInfo);
4851
4852 if (IterHandle != CurValue) {
4853 // If the iterator instruction was recursively deleted, start over at the
4854 // start of the block.
4855 CurInstIterator = BB->begin();
4856 SunkAddrs.clear();
4857 }
4858 }
4859 ++NumMemoryInsts;
4860 return true;
4861}
4862
4863/// If there are any memory operands, use OptimizeMemoryInst to sink their
4864/// address computing into the block when possible / profitable.
4865bool CodeGenPrepare::optimizeInlineAsmInst(CallInst *CS) {
4866 bool MadeChange = false;
4867
4868 const TargetRegisterInfo *TRI =
4869 TM->getSubtargetImpl(*CS->getFunction())->getRegisterInfo();
4870 TargetLowering::AsmOperandInfoVector TargetConstraints =
4871 TLI->ParseConstraints(*DL, TRI, CS);
4872 unsigned ArgNo = 0;
4873 for (unsigned i = 0, e = TargetConstraints.size(); i != e; ++i) {
4874 TargetLowering::AsmOperandInfo &OpInfo = TargetConstraints[i];
4875
4876 // Compute the constraint code and ConstraintType to use.
4877 TLI->ComputeConstraintToUse(OpInfo, SDValue());
4878
4879 if (OpInfo.ConstraintType == TargetLowering::C_Memory &&
4880 OpInfo.isIndirect) {
4881 Value *OpVal = CS->getArgOperand(ArgNo++);
4882 MadeChange |= optimizeMemoryInst(CS, OpVal, OpVal->getType(), ~0u);
4883 } else if (OpInfo.Type == InlineAsm::isInput)
4884 ArgNo++;
4885 }
4886
4887 return MadeChange;
4888}
4889
4890/// \brief Check if all the uses of \p Val are equivalent (or free) zero or
4891/// sign extensions.
4892static bool hasSameExtUse(Value *Val, const TargetLowering &TLI) {
4893 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\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 4893, __PRETTY_FUNCTION__))
;
4894 const Instruction *FirstUser = cast<Instruction>(*Val->user_begin());
4895 bool IsSExt = isa<SExtInst>(FirstUser);
4896 Type *ExtTy = FirstUser->getType();
4897 for (const User *U : Val->users()) {
4898 const Instruction *UI = cast<Instruction>(U);
4899 if ((IsSExt && !isa<SExtInst>(UI)) || (!IsSExt && !isa<ZExtInst>(UI)))
4900 return false;
4901 Type *CurTy = UI->getType();
4902 // Same input and output types: Same instruction after CSE.
4903 if (CurTy == ExtTy)
4904 continue;
4905
4906 // If IsSExt is true, we are in this situation:
4907 // a = Val
4908 // b = sext ty1 a to ty2
4909 // c = sext ty1 a to ty3
4910 // Assuming ty2 is shorter than ty3, this could be turned into:
4911 // a = Val
4912 // b = sext ty1 a to ty2
4913 // c = sext ty2 b to ty3
4914 // However, the last sext is not free.
4915 if (IsSExt)
4916 return false;
4917
4918 // This is a ZExt, maybe this is free to extend from one type to another.
4919 // In that case, we would not account for a different use.
4920 Type *NarrowTy;
4921 Type *LargeTy;
4922 if (ExtTy->getScalarType()->getIntegerBitWidth() >
4923 CurTy->getScalarType()->getIntegerBitWidth()) {
4924 NarrowTy = CurTy;
4925 LargeTy = ExtTy;
4926 } else {
4927 NarrowTy = ExtTy;
4928 LargeTy = CurTy;
4929 }
4930
4931 if (!TLI.isZExtFree(NarrowTy, LargeTy))
4932 return false;
4933 }
4934 // All uses are the same or can be derived from one another for free.
4935 return true;
4936}
4937
4938/// \brief Try to speculatively promote extensions in \p Exts and continue
4939/// promoting through newly promoted operands recursively as far as doing so is
4940/// profitable. Save extensions profitably moved up, in \p ProfitablyMovedExts.
4941/// When some promotion happened, \p TPT contains the proper state to revert
4942/// them.
4943///
4944/// \return true if some promotion happened, false otherwise.
4945bool CodeGenPrepare::tryToPromoteExts(
4946 TypePromotionTransaction &TPT, const SmallVectorImpl<Instruction *> &Exts,
4947 SmallVectorImpl<Instruction *> &ProfitablyMovedExts,
4948 unsigned CreatedInstsCost) {
4949 bool Promoted = false;
4950
4951 // Iterate over all the extensions to try to promote them.
4952 for (auto I : Exts) {
4953 // Early check if we directly have ext(load).
4954 if (isa<LoadInst>(I->getOperand(0))) {
4955 ProfitablyMovedExts.push_back(I);
4956 continue;
4957 }
4958
4959 // Check whether or not we want to do any promotion. The reason we have
4960 // this check inside the for loop is to catch the case where an extension
4961 // is directly fed by a load because in such case the extension can be moved
4962 // up without any promotion on its operands.
4963 if (!TLI || !TLI->enableExtLdPromotion() || DisableExtLdPromotion)
4964 return false;
4965
4966 // Get the action to perform the promotion.
4967 TypePromotionHelper::Action TPH =
4968 TypePromotionHelper::getAction(I, InsertedInsts, *TLI, PromotedInsts);
4969 // Check if we can promote.
4970 if (!TPH) {
4971 // Save the current extension as we cannot move up through its operand.
4972 ProfitablyMovedExts.push_back(I);
4973 continue;
4974 }
4975
4976 // Save the current state.
4977 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
4978 TPT.getRestorationPoint();
4979 SmallVector<Instruction *, 4> NewExts;
4980 unsigned NewCreatedInstsCost = 0;
4981 unsigned ExtCost = !TLI->isExtFree(I);
4982 // Promote.
4983 Value *PromotedVal = TPH(I, TPT, PromotedInsts, NewCreatedInstsCost,
4984 &NewExts, nullptr, *TLI);
4985 assert(PromotedVal &&((PromotedVal && "TypePromotionHelper should have filtered out those cases"
) ? static_cast<void> (0) : __assert_fail ("PromotedVal && \"TypePromotionHelper should have filtered out those cases\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 4986, __PRETTY_FUNCTION__))
4986 "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\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 4986, __PRETTY_FUNCTION__))
;
4987
4988 // We would be able to merge only one extension in a load.
4989 // Therefore, if we have more than 1 new extension we heuristically
4990 // cut this search path, because it means we degrade the code quality.
4991 // With exactly 2, the transformation is neutral, because we will merge
4992 // one extension but leave one. However, we optimistically keep going,
4993 // because the new extension may be removed too.
4994 long long TotalCreatedInstsCost = CreatedInstsCost + NewCreatedInstsCost;
4995 // FIXME: It would be possible to propagate a negative value instead of
4996 // conservatively ceiling it to 0.
4997 TotalCreatedInstsCost =
4998 std::max((long long)0, (TotalCreatedInstsCost - ExtCost));
4999 if (!StressExtLdPromotion &&
5000 (TotalCreatedInstsCost > 1 ||
5001 !isPromotedInstructionLegal(*TLI, *DL, PromotedVal))) {
5002 // This promotion is not profitable, rollback to the previous state, and
5003 // save the current extension in ProfitablyMovedExts as the latest
5004 // speculative promotion turned out to be unprofitable.
5005 TPT.rollback(LastKnownGood);
5006 ProfitablyMovedExts.push_back(I);
5007 continue;
5008 }
5009 // Continue promoting NewExts as far as doing so is profitable.
5010 SmallVector<Instruction *, 2> NewlyMovedExts;
5011 (void)tryToPromoteExts(TPT, NewExts, NewlyMovedExts, TotalCreatedInstsCost);
5012 bool NewPromoted = false;
5013 for (auto ExtInst : NewlyMovedExts) {
5014 Instruction *MovedExt = cast<Instruction>(ExtInst);
5015 Value *ExtOperand = MovedExt->getOperand(0);
5016 // If we have reached to a load, we need this extra profitability check
5017 // as it could potentially be merged into an ext(load).
5018 if (isa<LoadInst>(ExtOperand) &&
5019 !(StressExtLdPromotion || NewCreatedInstsCost <= ExtCost ||
5020 (ExtOperand->hasOneUse() || hasSameExtUse(ExtOperand, *TLI))))
5021 continue;
5022
5023 ProfitablyMovedExts.push_back(MovedExt);
5024 NewPromoted = true;
5025 }
5026
5027 // If none of speculative promotions for NewExts is profitable, rollback
5028 // and save the current extension (I) as the last profitable extension.
5029 if (!NewPromoted) {
5030 TPT.rollback(LastKnownGood);
5031 ProfitablyMovedExts.push_back(I);
5032 continue;
5033 }
5034 // The promotion is profitable.
5035 Promoted = true;
5036 }
5037 return Promoted;
5038}
5039
5040/// Merging redundant sexts when one is dominating the other.
5041bool CodeGenPrepare::mergeSExts(Function &F) {
5042 DominatorTree DT(F);
5043 bool Changed = false;
5044 for (auto &Entry : ValToSExtendedUses) {
5045 SExts &Insts = Entry.second;
5046 SExts CurPts;
5047 for (Instruction *Inst : Insts) {
5048 if (RemovedInsts.count(Inst) || !isa<SExtInst>(Inst) ||
5049 Inst->getOperand(0) != Entry.first)
5050 continue;
5051 bool inserted = false;
5052 for (auto &Pt : CurPts) {
5053 if (DT.dominates(Inst, Pt)) {
5054 Pt->replaceAllUsesWith(Inst);
5055 RemovedInsts.insert(Pt);
5056 Pt->removeFromParent();
5057 Pt = Inst;
5058 inserted = true;
5059 Changed = true;
5060 break;
5061 }
5062 if (!DT.dominates(Pt, Inst))
5063 // Give up if we need to merge in a common dominator as the
5064 // expermients show it is not profitable.
5065 continue;
5066 Inst->replaceAllUsesWith(Pt);
5067 RemovedInsts.insert(Inst);
5068 Inst->removeFromParent();
5069 inserted = true;
5070 Changed = true;
5071 break;
5072 }
5073 if (!inserted)
5074 CurPts.push_back(Inst);
5075 }
5076 }
5077 return Changed;
5078}
5079
5080/// Return true, if an ext(load) can be formed from an extension in
5081/// \p MovedExts.
5082bool CodeGenPrepare::canFormExtLd(
5083 const SmallVectorImpl<Instruction *> &MovedExts, LoadInst *&LI,
5084 Instruction *&Inst, bool HasPromoted) {
5085 for (auto *MovedExtInst : MovedExts) {
5086 if (isa<LoadInst>(MovedExtInst->getOperand(0))) {
5087 LI = cast<LoadInst>(MovedExtInst->getOperand(0));
5088 Inst = MovedExtInst;
5089 break;
5090 }
5091 }
5092 if (!LI)
5093 return false;
5094
5095 // If they're already in the same block, there's nothing to do.
5096 // Make the cheap checks first if we did not promote.
5097 // If we promoted, we need to check if it is indeed profitable.
5098 if (!HasPromoted && LI->getParent() == Inst->getParent())
5099 return false;
5100
5101 return TLI->isExtLoad(LI, Inst, *DL);
5102}
5103
5104/// Move a zext or sext fed by a load into the same basic block as the load,
5105/// unless conditions are unfavorable. This allows SelectionDAG to fold the
5106/// extend into the load.
5107///
5108/// E.g.,
5109/// \code
5110/// %ld = load i32* %addr
5111/// %add = add nuw i32 %ld, 4
5112/// %zext = zext i32 %add to i64
5113// \endcode
5114/// =>
5115/// \code
5116/// %ld = load i32* %addr
5117/// %zext = zext i32 %ld to i64
5118/// %add = add nuw i64 %zext, 4
5119/// \encode
5120/// Note that the promotion in %add to i64 is done in tryToPromoteExts(), which
5121/// allow us to match zext(load i32*) to i64.
5122///
5123/// Also, try to promote the computations used to obtain a sign extended
5124/// value used into memory accesses.
5125/// E.g.,
5126/// \code
5127/// a = add nsw i32 b, 3
5128/// d = sext i32 a to i64
5129/// e = getelementptr ..., i64 d
5130/// \endcode
5131/// =>
5132/// \code
5133/// f = sext i32 b to i64
5134/// a = add nsw i64 f, 3
5135/// e = getelementptr ..., i64 a
5136/// \endcode
5137///
5138/// \p Inst[in/out] the extension may be modified during the process if some
5139/// promotions apply.
5140bool CodeGenPrepare::optimizeExt(Instruction *&Inst) {
5141 // ExtLoad formation and address type promotion infrastructure requires TLI to
5142 // be effective.
5143 if (!TLI)
5144 return false;
5145
5146 bool AllowPromotionWithoutCommonHeader = false;
5147 /// See if it is an interesting sext operations for the address type
5148 /// promotion before trying to promote it, e.g., the ones with the right
5149 /// type and used in memory accesses.
5150 bool ATPConsiderable = TTI->shouldConsiderAddressTypePromotion(
5151 *Inst, AllowPromotionWithoutCommonHeader);
5152 TypePromotionTransaction TPT(RemovedInsts);
5153 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
5154 TPT.getRestorationPoint();
5155 SmallVector<Instruction *, 1> Exts;
5156 SmallVector<Instruction *, 2> SpeculativelyMovedExts;
5157 Exts.push_back(Inst);
5158
5159 bool HasPromoted = tryToPromoteExts(TPT, Exts, SpeculativelyMovedExts);
5160
5161 // Look for a load being extended.
5162 LoadInst *LI = nullptr;
5163 Instruction *ExtFedByLoad;
5164
5165 // Try to promote a chain of computation if it allows to form an extended
5166 // load.
5167 if (canFormExtLd(SpeculativelyMovedExts, LI, ExtFedByLoad, HasPromoted)) {
5168 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\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 5168, __PRETTY_FUNCTION__))
;
5169 TPT.commit();
5170 // Move the extend into the same block as the load
5171 ExtFedByLoad->moveAfter(LI);
5172 // CGP does not check if the zext would be speculatively executed when moved
5173 // to the same basic block as the load. Preserving its original location
5174 // would pessimize the debugging experience, as well as negatively impact
5175 // the quality of sample pgo. We don't want to use "line 0" as that has a
5176 // size cost in the line-table section and logically the zext can be seen as
5177 // part of the load. Therefore we conservatively reuse the same debug
5178 // location for the load and the zext.
5179 ExtFedByLoad->setDebugLoc(LI->getDebugLoc());
5180 ++NumExtsMoved;
5181 Inst = ExtFedByLoad;
5182 return true;
5183 }
5184
5185 // Continue promoting SExts if known as considerable depending on targets.
5186 if (ATPConsiderable &&
5187 performAddressTypePromotion(Inst, AllowPromotionWithoutCommonHeader,
5188 HasPromoted, TPT, SpeculativelyMovedExts))
5189 return true;
5190
5191 TPT.rollback(LastKnownGood);
5192 return false;
5193}
5194
5195// Perform address type promotion if doing so is profitable.
5196// If AllowPromotionWithoutCommonHeader == false, we should find other sext
5197// instructions that sign extended the same initial value. However, if
5198// AllowPromotionWithoutCommonHeader == true, we expect promoting the
5199// extension is just profitable.
5200bool CodeGenPrepare::performAddressTypePromotion(
5201 Instruction *&Inst, bool AllowPromotionWithoutCommonHeader,
5202 bool HasPromoted, TypePromotionTransaction &TPT,
5203 SmallVectorImpl<Instruction *> &SpeculativelyMovedExts) {
5204 bool Promoted = false;
5205 SmallPtrSet<Instruction *, 1> UnhandledExts;
5206 bool AllSeenFirst = true;
5207 for (auto I : SpeculativelyMovedExts) {
5208 Value *HeadOfChain = I->getOperand(0);
5209 DenseMap<Value *, Instruction *>::iterator AlreadySeen =
5210 SeenChainsForSExt.find(HeadOfChain);
5211 // If there is an unhandled SExt which has the same header, try to promote
5212 // it as well.
5213 if (AlreadySeen != SeenChainsForSExt.end()) {
5214 if (AlreadySeen->second != nullptr)
5215 UnhandledExts.insert(AlreadySeen->second);
5216 AllSeenFirst = false;
5217 }
5218 }
5219
5220 if (!AllSeenFirst || (AllowPromotionWithoutCommonHeader &&
5221 SpeculativelyMovedExts.size() == 1)) {
5222 TPT.commit();
5223 if (HasPromoted)
5224 Promoted = true;
5225 for (auto I : SpeculativelyMovedExts) {
5226 Value *HeadOfChain = I->getOperand(0);
5227 SeenChainsForSExt[HeadOfChain] = nullptr;
5228 ValToSExtendedUses[HeadOfChain].push_back(I);
5229 }
5230 // Update Inst as promotion happen.
5231 Inst = SpeculativelyMovedExts.pop_back_val();
5232 } else {
5233 // This is the first chain visited from the header, keep the current chain
5234 // as unhandled. Defer to promote this until we encounter another SExt
5235 // chain derived from the same header.
5236 for (auto I : SpeculativelyMovedExts) {
5237 Value *HeadOfChain = I->getOperand(0);
5238 SeenChainsForSExt[HeadOfChain] = Inst;
5239 }
5240 return false;
5241 }
5242
5243 if (!AllSeenFirst && !UnhandledExts.empty())
5244 for (auto VisitedSExt : UnhandledExts) {
5245 if (RemovedInsts.count(VisitedSExt))
5246 continue;
5247 TypePromotionTransaction TPT(RemovedInsts);
5248 SmallVector<Instruction *, 1> Exts;
5249 SmallVector<Instruction *, 2> Chains;
5250 Exts.push_back(VisitedSExt);
5251 bool HasPromoted = tryToPromoteExts(TPT, Exts, Chains);
5252 TPT.commit();
5253 if (HasPromoted)
5254 Promoted = true;
5255 for (auto I : Chains) {
5256 Value *HeadOfChain = I->getOperand(0);
5257 // Mark this as handled.
5258 SeenChainsForSExt[HeadOfChain] = nullptr;
5259 ValToSExtendedUses[HeadOfChain].push_back(I);
5260 }
5261 }
5262 return Promoted;
5263}
5264
5265bool CodeGenPrepare::optimizeExtUses(Instruction *I) {
5266 BasicBlock *DefBB = I->getParent();
5267
5268 // If the result of a {s|z}ext and its source are both live out, rewrite all
5269 // other uses of the source with result of extension.
5270 Value *Src = I->getOperand(0);
5271 if (Src->hasOneUse())
5272 return false;
5273
5274 // Only do this xform if truncating is free.
5275 if (TLI && !TLI->isTruncateFree(I->getType(), Src->getType()))
5276 return false;
5277
5278 // Only safe to perform the optimization if the source is also defined in
5279 // this block.
5280 if (!isa<Instruction>(Src) || DefBB != cast<Instruction>(Src)->getParent())
5281 return false;
5282
5283 bool DefIsLiveOut = false;
5284 for (User *U : I->users()) {
5285 Instruction *UI = cast<Instruction>(U);
5286
5287 // Figure out which BB this ext is used in.
5288 BasicBlock *UserBB = UI->getParent();
5289 if (UserBB == DefBB) continue;
5290 DefIsLiveOut = true;
5291 break;
5292 }
5293 if (!DefIsLiveOut)
5294 return false;
5295
5296 // Make sure none of the uses are PHI nodes.
5297 for (User *U : Src->users()) {
5298 Instruction *UI = cast<Instruction>(U);
5299 BasicBlock *UserBB = UI->getParent();
5300 if (UserBB == DefBB) continue;
5301 // Be conservative. We don't want this xform to end up introducing
5302 // reloads just before load / store instructions.
5303 if (isa<PHINode>(UI) || isa<LoadInst>(UI) || isa<StoreInst>(UI))
5304 return false;
5305 }
5306
5307 // InsertedTruncs - Only insert one trunc in each block once.
5308 DenseMap<BasicBlock*, Instruction*> InsertedTruncs;
5309
5310 bool MadeChange = false;
5311 for (Use &U : Src->uses()) {
5312 Instruction *User = cast<Instruction>(U.getUser());
5313
5314 // Figure out which BB this ext is used in.
5315 BasicBlock *UserBB = User->getParent();
5316 if (UserBB == DefBB) continue;
5317
5318 // Both src and def are live in this block. Rewrite the use.
5319 Instruction *&InsertedTrunc = InsertedTruncs[UserBB];
5320
5321 if (!InsertedTrunc) {
5322 BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
5323 assert(InsertPt != UserBB->end())((InsertPt != UserBB->end()) ? static_cast<void> (0)
: __assert_fail ("InsertPt != UserBB->end()", "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 5323, __PRETTY_FUNCTION__))
;
5324 InsertedTrunc = new TruncInst(I, Src->getType(), "", &*InsertPt);
5325 InsertedInsts.insert(InsertedTrunc);
5326 }
5327
5328 // Replace a use of the {s|z}ext source with a use of the result.
5329 U = InsertedTrunc;
5330 ++NumExtUses;
5331 MadeChange = true;
5332 }
5333
5334 return MadeChange;
5335}
5336
5337// Find loads whose uses only use some of the loaded value's bits. Add an "and"
5338// just after the load if the target can fold this into one extload instruction,
5339// with the hope of eliminating some of the other later "and" instructions using
5340// the loaded value. "and"s that are made trivially redundant by the insertion
5341// of the new "and" are removed by this function, while others (e.g. those whose
5342// path from the load goes through a phi) are left for isel to potentially
5343// remove.
5344//
5345// For example:
5346//
5347// b0:
5348// x = load i32
5349// ...
5350// b1:
5351// y = and x, 0xff
5352// z = use y
5353//
5354// becomes:
5355//
5356// b0:
5357// x = load i32
5358// x' = and x, 0xff
5359// ...
5360// b1:
5361// z = use x'
5362//
5363// whereas:
5364//
5365// b0:
5366// x1 = load i32
5367// ...
5368// b1:
5369// x2 = load i32
5370// ...
5371// b2:
5372// x = phi x1, x2
5373// y = and x, 0xff
5374//
5375// becomes (after a call to optimizeLoadExt for each load):
5376//
5377// b0:
5378// x1 = load i32
5379// x1' = and x1, 0xff
5380// ...
5381// b1:
5382// x2 = load i32
5383// x2' = and x2, 0xff
5384// ...
5385// b2:
5386// x = phi x1', x2'
5387// y = and x, 0xff
5388bool CodeGenPrepare::optimizeLoadExt(LoadInst *Load) {
5389 if (!Load->isSimple() ||
5390 !(Load->getType()->isIntegerTy() || Load->getType()->isPointerTy()))
5391 return false;
5392
5393 // Skip loads we've already transformed.
5394 if (Load->hasOneUse() &&
5395 InsertedInsts.count(cast<Instruction>(*Load->user_begin())))
5396 return false;
5397
5398 // Look at all uses of Load, looking through phis, to determine how many bits
5399 // of the loaded value are needed.
5400 SmallVector<Instruction *, 8> WorkList;
5401 SmallPtrSet<Instruction *, 16> Visited;
5402 SmallVector<Instruction *, 8> AndsToMaybeRemove;
5403 for (auto *U : Load->users())
5404 WorkList.push_back(cast<Instruction>(U));
5405
5406 EVT LoadResultVT = TLI->getValueType(*DL, Load->getType());
5407 unsigned BitWidth = LoadResultVT.getSizeInBits();
5408 APInt DemandBits(BitWidth, 0);
5409 APInt WidestAndBits(BitWidth, 0);
5410
5411 while (!WorkList.empty()) {
5412 Instruction *I = WorkList.back();
5413 WorkList.pop_back();
5414
5415 // Break use-def graph loops.
5416 if (!Visited.insert(I).second)
5417 continue;
5418
5419 // For a PHI node, push all of its users.
5420 if (auto *Phi = dyn_cast<PHINode>(I)) {
5421 for (auto *U : Phi->users())
5422 WorkList.push_back(cast<Instruction>(U));
5423 continue;
5424 }
5425
5426 switch (I->getOpcode()) {
5427 case Instruction::And: {
5428 auto *AndC = dyn_cast<ConstantInt>(I->getOperand(1));
5429 if (!AndC)
5430 return false;
5431 APInt AndBits = AndC->getValue();
5432 DemandBits |= AndBits;
5433 // Keep track of the widest and mask we see.
5434 if (AndBits.ugt(WidestAndBits))
5435 WidestAndBits = AndBits;
5436 if (AndBits == WidestAndBits && I->getOperand(0) == Load)
5437 AndsToMaybeRemove.push_back(I);
5438 break;
5439 }
5440
5441 case Instruction::Shl: {
5442 auto *ShlC = dyn_cast<ConstantInt>(I->getOperand(1));
5443 if (!ShlC)
5444 return false;
5445 uint64_t ShiftAmt = ShlC->getLimitedValue(BitWidth - 1);
5446 DemandBits.setLowBits(BitWidth - ShiftAmt);
5447 break;
5448 }
5449
5450 case Instruction::Trunc: {
5451 EVT TruncVT = TLI->getValueType(*DL, I->getType());
5452 unsigned TruncBitWidth = TruncVT.getSizeInBits();
5453 DemandBits.setLowBits(TruncBitWidth);
5454 break;
5455 }
5456
5457 default:
5458 return false;
5459 }
5460 }
5461
5462 uint32_t ActiveBits = DemandBits.getActiveBits();
5463 // Avoid hoisting (and (load x) 1) since it is unlikely to be folded by the
5464 // target even if isLoadExtLegal says an i1 EXTLOAD is valid. For example,
5465 // for the AArch64 target isLoadExtLegal(ZEXTLOAD, i32, i1) returns true, but
5466 // (and (load x) 1) is not matched as a single instruction, rather as a LDR
5467 // followed by an AND.
5468 // TODO: Look into removing this restriction by fixing backends to either
5469 // return false for isLoadExtLegal for i1 or have them select this pattern to
5470 // a single instruction.
5471 //
5472 // Also avoid hoisting if we didn't see any ands with the exact DemandBits
5473 // mask, since these are the only ands that will be removed by isel.
5474 if (ActiveBits <= 1 || !DemandBits.isMask(ActiveBits) ||
5475 WidestAndBits != DemandBits)
5476 return false;
5477
5478 LLVMContext &Ctx = Load->getType()->getContext();
5479 Type *TruncTy = Type::getIntNTy(Ctx, ActiveBits);
5480 EVT TruncVT = TLI->getValueType(*DL, TruncTy);
5481
5482 // Reject cases that won't be matched as extloads.
5483 if (!LoadResultVT.bitsGT(TruncVT) || !TruncVT.isRound() ||
5484 !TLI->isLoadExtLegal(ISD::ZEXTLOAD, LoadResultVT, TruncVT))
5485 return false;
5486
5487 IRBuilder<> Builder(Load->getNextNode());
5488 auto *NewAnd = dyn_cast<Instruction>(
5489 Builder.CreateAnd(Load, ConstantInt::get(Ctx, DemandBits)));
5490 // Mark this instruction as "inserted by CGP", so that other
5491 // optimizations don't touch it.
5492 InsertedInsts.insert(NewAnd);
5493
5494 // Replace all uses of load with new and (except for the use of load in the
5495 // new and itself).
5496 Load->replaceAllUsesWith(NewAnd);
5497 NewAnd->setOperand(0, Load);
5498
5499 // Remove any and instructions that are now redundant.
5500 for (auto *And : AndsToMaybeRemove)
5501 // Check that the and mask is the same as the one we decided to put on the
5502 // new and.
5503 if (cast<ConstantInt>(And->getOperand(1))->getValue() == DemandBits) {
5504 And->replaceAllUsesWith(NewAnd);
5505 if (&*CurInstIterator == And)
5506 CurInstIterator = std::next(And->getIterator());
5507 And->eraseFromParent();
5508 ++NumAndUses;
5509 }
5510
5511 ++NumAndsAdded;
5512 return true;
5513}
5514
5515/// Check if V (an operand of a select instruction) is an expensive instruction
5516/// that is only used once.
5517static bool sinkSelectOperand(const TargetTransformInfo *TTI, Value *V) {
5518 auto *I = dyn_cast<Instruction>(V);
5519 // If it's safe to speculatively execute, then it should not have side
5520 // effects; therefore, it's safe to sink and possibly *not* execute.
5521 return I && I->hasOneUse() && isSafeToSpeculativelyExecute(I) &&
5522 TTI->getUserCost(I) >= TargetTransformInfo::TCC_Expensive;
5523}
5524
5525/// Returns true if a SelectInst should be turned into an explicit branch.
5526static bool isFormingBranchFromSelectProfitable(const TargetTransformInfo *TTI,
5527 const TargetLowering *TLI,
5528 SelectInst *SI) {
5529 // If even a predictable select is cheap, then a branch can't be cheaper.
5530 if (!TLI->isPredictableSelectExpensive())
5531 return false;
5532
5533 // FIXME: This should use the same heuristics as IfConversion to determine
5534 // whether a select is better represented as a branch.
5535
5536 // If metadata tells us that the select condition is obviously predictable,
5537 // then we want to replace the select with a branch.
5538 uint64_t TrueWeight, FalseWeight;
5539 if (SI->extractProfMetadata(TrueWeight, FalseWeight)) {
5540 uint64_t Max = std::max(TrueWeight, FalseWeight);
5541 uint64_t Sum = TrueWeight + FalseWeight;
5542 if (Sum != 0) {
5543 auto Probability = BranchProbability::getBranchProbability(Max, Sum);
5544 if (Probability > TLI->getPredictableBranchThreshold())
5545 return true;
5546 }
5547 }
5548
5549 CmpInst *Cmp = dyn_cast<CmpInst>(SI->getCondition());
5550
5551 // If a branch is predictable, an out-of-order CPU can avoid blocking on its
5552 // comparison condition. If the compare has more than one use, there's
5553 // probably another cmov or setcc around, so it's not worth emitting a branch.
5554 if (!Cmp || !Cmp->hasOneUse())
5555 return false;
5556
5557 // If either operand of the select is expensive and only needed on one side
5558 // of the select, we should form a branch.
5559 if (sinkSelectOperand(TTI, SI->getTrueValue()) ||
5560 sinkSelectOperand(TTI, SI->getFalseValue()))
5561 return true;
5562
5563 return false;
5564}
5565
5566/// If \p isTrue is true, return the true value of \p SI, otherwise return
5567/// false value of \p SI. If the true/false value of \p SI is defined by any
5568/// select instructions in \p Selects, look through the defining select
5569/// instruction until the true/false value is not defined in \p Selects.
5570static Value *getTrueOrFalseValue(
5571 SelectInst *SI, bool isTrue,
5572 const SmallPtrSet<const Instruction *, 2> &Selects) {
5573 Value *V;
5574
5575 for (SelectInst *DefSI = SI; DefSI != nullptr && Selects.count(DefSI);
5576 DefSI = dyn_cast<SelectInst>(V)) {
5577 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\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 5578, __PRETTY_FUNCTION__))
5578 "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\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 5578, __PRETTY_FUNCTION__))
;
5579 V = (isTrue ? DefSI->getTrueValue() : DefSI->getFalseValue());
5580 }
5581 return V;
5582}
5583
5584/// If we have a SelectInst that will likely profit from branch prediction,
5585/// turn it into a branch.
5586bool CodeGenPrepare::optimizeSelectInst(SelectInst *SI) {
5587 // Find all consecutive select instructions that share the same condition.
5588 SmallVector<SelectInst *, 2> ASI;
5589 ASI.push_back(SI);
5590 for (BasicBlock::iterator It = ++BasicBlock::iterator(SI);
5591 It != SI->getParent()->end(); ++It) {
5592 SelectInst *I = dyn_cast<SelectInst>(&*It);
5593 if (I && SI->getCondition() == I->getCondition()) {
5594 ASI.push_back(I);
5595 } else {
5596 break;
5597 }
5598 }
5599
5600 SelectInst *LastSI = ASI.back();
5601 // Increment the current iterator to skip all the rest of select instructions
5602 // because they will be either "not lowered" or "all lowered" to branch.
5603 CurInstIterator = std::next(LastSI->getIterator());
5604
5605 bool VectorCond = !SI->getCondition()->getType()->isIntegerTy(1);
5606
5607 // Can we convert the 'select' to CF ?
5608 if (DisableSelectToBranch || OptSize || !TLI || VectorCond ||
5609 SI->getMetadata(LLVMContext::MD_unpredictable))
5610 return false;
5611
5612 TargetLowering::SelectSupportKind SelectKind;
5613 if (VectorCond)
5614 SelectKind = TargetLowering::VectorMaskSelect;
5615 else if (SI->getType()->isVectorTy())
5616 SelectKind = TargetLowering::ScalarCondVectorVal;
5617 else
5618 SelectKind = TargetLowering::ScalarValSelect;
5619
5620 if (TLI->isSelectSupported(SelectKind) &&
5621 !isFormingBranchFromSelectProfitable(TTI, TLI, SI))
5622 return false;
5623
5624 ModifiedDT = true;
5625
5626 // Transform a sequence like this:
5627 // start:
5628 // %cmp = cmp uge i32 %a, %b
5629 // %sel = select i1 %cmp, i32 %c, i32 %d
5630 //
5631 // Into:
5632 // start:
5633 // %cmp = cmp uge i32 %a, %b
5634 // br i1 %cmp, label %select.true, label %select.false
5635 // select.true:
5636 // br label %select.end
5637 // select.false:
5638 // br label %select.end
5639 // select.end:
5640 // %sel = phi i32 [ %c, %select.true ], [ %d, %select.false ]
5641 //
5642 // In addition, we may sink instructions that produce %c or %d from
5643 // the entry block into the destination(s) of the new branch.
5644 // If the true or false blocks do not contain a sunken instruction, that
5645 // block and its branch may be optimized away. In that case, one side of the
5646 // first branch will point directly to select.end, and the corresponding PHI
5647 // predecessor block will be the start block.
5648
5649 // First, we split the block containing the select into 2 blocks.
5650 BasicBlock *StartBlock = SI->getParent();
5651 BasicBlock::iterator SplitPt = ++(BasicBlock::iterator(LastSI));
5652 BasicBlock *EndBlock = StartBlock->splitBasicBlock(SplitPt, "select.end");
5653
5654 // Delete the unconditional branch that was just created by the split.
5655 StartBlock->getTerminator()->eraseFromParent();
5656
5657 // These are the new basic blocks for the conditional branch.
5658 // At least one will become an actual new basic block.
5659 BasicBlock *TrueBlock = nullptr;
5660 BasicBlock *FalseBlock = nullptr;
5661 BranchInst *TrueBranch = nullptr;
5662 BranchInst *FalseBranch = nullptr;
5663
5664 // Sink expensive instructions into the conditional blocks to avoid executing
5665 // them speculatively.
5666 for (SelectInst *SI : ASI) {
5667 if (sinkSelectOperand(TTI, SI->getTrueValue())) {
5668 if (TrueBlock == nullptr) {
5669 TrueBlock = BasicBlock::Create(SI->getContext(), "select.true.sink",
5670 EndBlock->getParent(), EndBlock);
5671 TrueBranch = BranchInst::Create(EndBlock, TrueBlock);
5672 }
5673 auto *TrueInst = cast<Instruction>(SI->getTrueValue());
5674 TrueInst->moveBefore(TrueBranch);
5675 }
5676 if (sinkSelectOperand(TTI, SI->getFalseValue())) {
5677 if (FalseBlock == nullptr) {
5678 FalseBlock = BasicBlock::Create(SI->getContext(), "select.false.sink",
5679 EndBlock->getParent(), EndBlock);
5680 FalseBranch = BranchInst::Create(EndBlock, FalseBlock);
5681 }
5682 auto *FalseInst = cast<Instruction>(SI->getFalseValue());
5683 FalseInst->moveBefore(FalseBranch);
5684 }
5685 }
5686
5687 // If there was nothing to sink, then arbitrarily choose the 'false' side
5688 // for a new input value to the PHI.
5689 if (TrueBlock == FalseBlock) {
5690 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\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 5691, __PRETTY_FUNCTION__))
5691 "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\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 5691, __PRETTY_FUNCTION__))
;
5692
5693 FalseBlock = BasicBlock::Create(SI->getContext(), "select.false",
5694 EndBlock->getParent(), EndBlock);
5695 BranchInst::Create(EndBlock, FalseBlock);
5696 }
5697
5698 // Insert the real conditional branch based on the original condition.
5699 // If we did not create a new block for one of the 'true' or 'false' paths
5700 // of the condition, it means that side of the branch goes to the end block
5701 // directly and the path originates from the start block from the point of
5702 // view of the new PHI.
5703 BasicBlock *TT, *FT;
5704 if (TrueBlock == nullptr) {
5705 TT = EndBlock;
5706 FT = FalseBlock;
5707 TrueBlock = StartBlock;
5708 } else if (FalseBlock == nullptr) {
5709 TT = TrueBlock;
5710 FT = EndBlock;
5711 FalseBlock = StartBlock;
5712 } else {
5713 TT = TrueBlock;
5714 FT = FalseBlock;
5715 }
5716 IRBuilder<>(SI).CreateCondBr(SI->getCondition(), TT, FT, SI);
5717
5718 SmallPtrSet<const Instruction *, 2> INS;
5719 INS.insert(ASI.begin(), ASI.end());
5720 // Use reverse iterator because later select may use the value of the
5721 // earlier select, and we need to propagate value through earlier select
5722 // to get the PHI operand.
5723 for (auto It = ASI.rbegin(); It != ASI.rend(); ++It) {
5724 SelectInst *SI = *It;
5725 // The select itself is replaced with a PHI Node.
5726 PHINode *PN = PHINode::Create(SI->getType(), 2, "", &EndBlock->front());
5727 PN->takeName(SI);
5728 PN->addIncoming(getTrueOrFalseValue(SI, true, INS), TrueBlock);
5729 PN->addIncoming(getTrueOrFalseValue(SI, false, INS), FalseBlock);
5730
5731 SI->replaceAllUsesWith(PN);
5732 SI->eraseFromParent();
5733 INS.erase(SI);
5734 ++NumSelectsExpanded;
5735 }
5736
5737 // Instruct OptimizeBlock to skip to the next block.
5738 CurInstIterator = StartBlock->end();
5739 return true;
5740}
5741
5742static bool isBroadcastShuffle(ShuffleVectorInst *SVI) {
5743 SmallVector<int, 16> Mask(SVI->getShuffleMask());
5744 int SplatElem = -1;
5745 for (unsigned i = 0; i < Mask.size(); ++i) {
5746 if (SplatElem != -1 && Mask[i] != -1 && Mask[i] != SplatElem)
5747 return false;
5748 SplatElem = Mask[i];
5749 }
5750
5751 return true;
5752}
5753
5754/// Some targets have expensive vector shifts if the lanes aren't all the same
5755/// (e.g. x86 only introduced "vpsllvd" and friends with AVX2). In these cases
5756/// it's often worth sinking a shufflevector splat down to its use so that
5757/// codegen can spot all lanes are identical.
5758bool CodeGenPrepare::optimizeShuffleVectorInst(ShuffleVectorInst *SVI) {
5759 BasicBlock *DefBB = SVI->getParent();
5760
5761 // Only do this xform if variable vector shifts are particularly expensive.
5762 if (!TLI || !TLI->isVectorShiftByScalarCheap(SVI->getType()))
5763 return false;
5764
5765 // We only expect better codegen by sinking a shuffle if we can recognise a
5766 // constant splat.
5767 if (!isBroadcastShuffle(SVI))
5768 return false;
5769
5770 // InsertedShuffles - Only insert a shuffle in each block once.
5771 DenseMap<BasicBlock*, Instruction*> InsertedShuffles;
5772
5773 bool MadeChange = false;
5774 for (User *U : SVI->users()) {
5775 Instruction *UI = cast<Instruction>(U);
5776
5777 // Figure out which BB this ext is used in.
5778 BasicBlock *UserBB = UI->getParent();
5779 if (UserBB == DefBB) continue;
5780
5781 // For now only apply this when the splat is used by a shift instruction.
5782 if (!UI->isShift()) continue;
5783
5784 // Everything checks out, sink the shuffle if the user's block doesn't
5785 // already have a copy.
5786 Instruction *&InsertedShuffle = InsertedShuffles[UserBB];
5787
5788 if (!InsertedShuffle) {
5789 BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
5790 assert(InsertPt != UserBB->end())((InsertPt != UserBB->end()) ? static_cast<void> (0)
: __assert_fail ("InsertPt != UserBB->end()", "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 5790, __PRETTY_FUNCTION__))
;
5791 InsertedShuffle =
5792 new ShuffleVectorInst(SVI->getOperand(0), SVI->getOperand(1),
5793 SVI->getOperand(2), "", &*InsertPt);
5794 }
5795
5796 UI->replaceUsesOfWith(SVI, InsertedShuffle);
5797 MadeChange = true;
5798 }
5799
5800 // If we removed all uses, nuke the shuffle.
5801 if (SVI->use_empty()) {
5802 SVI->eraseFromParent();
5803 MadeChange = true;
5804 }
5805
5806 return MadeChange;
5807}
5808
5809bool CodeGenPrepare::optimizeSwitchInst(SwitchInst *SI) {
5810 if (!TLI || !DL)
5811 return false;
5812
5813 Value *Cond = SI->getCondition();
5814 Type *OldType = Cond->getType();
5815 LLVMContext &Context = Cond->getContext();
5816 MVT RegType = TLI->getRegisterType(Context, TLI->getValueType(*DL, OldType));
5817 unsigned RegWidth = RegType.getSizeInBits();
5818
5819 if (RegWidth <= cast<IntegerType>(OldType)->getBitWidth())
5820 return false;
5821
5822 // If the register width is greater than the type width, expand the condition
5823 // of the switch instruction and each case constant to the width of the
5824 // register. By widening the type of the switch condition, subsequent
5825 // comparisons (for case comparisons) will not need to be extended to the
5826 // preferred register width, so we will potentially eliminate N-1 extends,
5827 // where N is the number of cases in the switch.
5828 auto *NewType = Type::getIntNTy(Context, RegWidth);
5829
5830 // Zero-extend the switch condition and case constants unless the switch
5831 // condition is a function argument that is already being sign-extended.
5832 // In that case, we can avoid an unnecessary mask/extension by sign-extending
5833 // everything instead.
5834 Instruction::CastOps ExtType = Instruction::ZExt;
5835 if (auto *Arg = dyn_cast<Argument>(Cond))
5836 if (Arg->hasSExtAttr())
5837 ExtType = Instruction::SExt;
5838
5839 auto *ExtInst = CastInst::Create(ExtType, Cond, NewType);
5840 ExtInst->insertBefore(SI);
5841 SI->setCondition(ExtInst);
5842 for (auto Case : SI->cases()) {
5843 APInt NarrowConst = Case.getCaseValue()->getValue();
5844 APInt WideConst = (ExtType == Instruction::ZExt) ?
5845 NarrowConst.zext(RegWidth) : NarrowConst.sext(RegWidth);
5846 Case.setValue(ConstantInt::get(Context, WideConst));
5847 }
5848
5849 return true;
5850}
5851
5852
5853namespace {
5854
5855/// \brief Helper class to promote a scalar operation to a vector one.
5856/// This class is used to move downward extractelement transition.
5857/// E.g.,
5858/// a = vector_op <2 x i32>
5859/// b = extractelement <2 x i32> a, i32 0
5860/// c = scalar_op b
5861/// store c
5862///
5863/// =>
5864/// a = vector_op <2 x i32>
5865/// c = vector_op a (equivalent to scalar_op on the related lane)
5866/// * d = extractelement <2 x i32> c, i32 0
5867/// * store d
5868/// Assuming both extractelement and store can be combine, we get rid of the
5869/// transition.
5870class VectorPromoteHelper {
5871 /// DataLayout associated with the current module.
5872 const DataLayout &DL;
5873
5874 /// Used to perform some checks on the legality of vector operations.
5875 const TargetLowering &TLI;
5876
5877 /// Used to estimated the cost of the promoted chain.
5878 const TargetTransformInfo &TTI;
5879
5880 /// The transition being moved downwards.
5881 Instruction *Transition;
5882
5883 /// The sequence of instructions to be promoted.
5884 SmallVector<Instruction *, 4> InstsToBePromoted;
5885
5886 /// Cost of combining a store and an extract.
5887 unsigned StoreExtractCombineCost;
5888
5889 /// Instruction that will be combined with the transition.
5890 Instruction *CombineInst = nullptr;
5891
5892 /// \brief The instruction that represents the current end of the transition.
5893 /// Since we are faking the promotion until we reach the end of the chain
5894 /// of computation, we need a way to get the current end of the transition.
5895 Instruction *getEndOfTransition() const {
5896 if (InstsToBePromoted.empty())
5897 return Transition;
5898 return InstsToBePromoted.back();
5899 }
5900
5901 /// \brief Return the index of the original value in the transition.
5902 /// E.g., for "extractelement <2 x i32> c, i32 1" the original value,
5903 /// c, is at index 0.
5904 unsigned getTransitionOriginalValueIdx() const {
5905 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\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 5906, __PRETTY_FUNCTION__))
5906 "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\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 5906, __PRETTY_FUNCTION__))
;
5907 return 0;
5908 }
5909
5910 /// \brief Return the index of the index in the transition.
5911 /// E.g., for "extractelement <2 x i32> c, i32 0" the index
5912 /// is at index 1.
5913 unsigned getTransitionIdx() const {
5914 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\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 5915, __PRETTY_FUNCTION__))
5915 "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\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 5915, __PRETTY_FUNCTION__))
;
5916 return 1;
5917 }
5918
5919 /// \brief Get the type of the transition.
5920 /// This is the type of the original value.
5921 /// E.g., for "extractelement <2 x i32> c, i32 1" the type of the
5922 /// transition is <2 x i32>.
5923 Type *getTransitionType() const {
5924 return Transition->getOperand(getTransitionOriginalValueIdx())->getType();
5925 }
5926
5927 /// \brief Promote \p ToBePromoted by moving \p Def downward through.
5928 /// I.e., we have the following sequence:
5929 /// Def = Transition <ty1> a to <ty2>
5930 /// b = ToBePromoted <ty2> Def, ...
5931 /// =>
5932 /// b = ToBePromoted <ty1> a, ...
5933 /// Def = Transition <ty1> ToBePromoted to <ty2>
5934 void promoteImpl(Instruction *ToBePromoted);
5935
5936 /// \brief Check whether or not it is profitable to promote all the
5937 /// instructions enqueued to be promoted.
5938 bool isProfitableToPromote() {
5939 Value *ValIdx = Transition->getOperand(getTransitionOriginalValueIdx());
5940 unsigned Index = isa<ConstantInt>(ValIdx)
5941 ? cast<ConstantInt>(ValIdx)->getZExtValue()
5942 : -1;
5943 Type *PromotedType = getTransitionType();
5944
5945 StoreInst *ST = cast<StoreInst>(CombineInst);
5946 unsigned AS = ST->getPointerAddressSpace();
5947 unsigned Align = ST->getAlignment();
5948 // Check if this store is supported.
5949 if (!TLI.allowsMisalignedMemoryAccesses(
5950 TLI.getValueType(DL, ST->getValueOperand()->getType()), AS,
5951 Align)) {
5952 // If this is not supported, there is no way we can combine
5953 // the extract with the store.
5954 return false;
5955 }
5956
5957 // The scalar chain of computation has to pay for the transition
5958 // scalar to vector.
5959 // The vector chain has to account for the combining cost.
5960 uint64_t ScalarCost =
5961 TTI.getVectorInstrCost(Transition->getOpcode(), PromotedType, Index);
5962 uint64_t VectorCost = StoreExtractCombineCost;
5963 for (const auto &Inst : InstsToBePromoted) {
5964 // Compute the cost.
5965 // By construction, all instructions being promoted are arithmetic ones.
5966 // Moreover, one argument is a constant that can be viewed as a splat
5967 // constant.
5968 Value *Arg0 = Inst->getOperand(0);
5969 bool IsArg0Constant = isa<UndefValue>(Arg0) || isa<ConstantInt>(Arg0) ||
5970 isa<ConstantFP>(Arg0);
5971 TargetTransformInfo::OperandValueKind Arg0OVK =
5972 IsArg0Constant ? TargetTransformInfo::OK_UniformConstantValue
5973 : TargetTransformInfo::OK_AnyValue;
5974 TargetTransformInfo::OperandValueKind Arg1OVK =
5975 !IsArg0Constant ? TargetTransformInfo::OK_UniformConstantValue
5976 : TargetTransformInfo::OK_AnyValue;
5977 ScalarCost += TTI.getArithmeticInstrCost(
5978 Inst->getOpcode(), Inst->getType(), Arg0OVK, Arg1OVK);
5979 VectorCost += TTI.getArithmeticInstrCost(Inst->getOpcode(), PromotedType,
5980 Arg0OVK, Arg1OVK);
5981 }
5982 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)
5983 << 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)
;
5984 return ScalarCost > VectorCost;
5985 }
5986
5987 /// \brief Generate a constant vector with \p Val with the same
5988 /// number of elements as the transition.
5989 /// \p UseSplat defines whether or not \p Val should be replicated
5990 /// across the whole vector.
5991 /// In other words, if UseSplat == true, we generate <Val, Val, ..., Val>,
5992 /// otherwise we generate a vector with as many undef as possible:
5993 /// <undef, ..., undef, Val, undef, ..., undef> where \p Val is only
5994 /// used at the index of the extract.
5995 Value *getConstantVector(Constant *Val, bool UseSplat) const {
5996 unsigned ExtractIdx = std::numeric_limits<unsigned>::max();
5997 if (!UseSplat) {
5998 // If we cannot determine where the constant must be, we have to
5999 // use a splat constant.
6000 Value *ValExtractIdx = Transition->getOperand(getTransitionIdx());
6001 if (ConstantInt *CstVal = dyn_cast<ConstantInt>(ValExtractIdx))
6002 ExtractIdx = CstVal->getSExtValue();
6003 else
6004 UseSplat = true;
6005 }
6006
6007 unsigned End = getTransitionType()->getVectorNumElements();
6008 if (UseSplat)
6009 return ConstantVector::getSplat(End, Val);
6010
6011 SmallVector<Constant *, 4> ConstVec;
6012 UndefValue *UndefVal = UndefValue::get(Val->getType());
6013 for (unsigned Idx = 0; Idx != End; ++Idx) {
6014 if (Idx == ExtractIdx)
6015 ConstVec.push_back(Val);
6016 else
6017 ConstVec.push_back(UndefVal);
6018 }
6019 return ConstantVector::get(ConstVec);
6020 }
6021
6022 /// \brief Check if promoting to a vector type an operand at \p OperandIdx
6023 /// in \p Use can trigger undefined behavior.
6024 static bool canCauseUndefinedBehavior(const Instruction *Use,
6025 unsigned OperandIdx) {
6026 // This is not safe to introduce undef when the operand is on
6027 // the right hand side of a division-like instruction.
6028 if (OperandIdx != 1)
6029 return false;
6030 switch (Use->getOpcode()) {
6031 default:
6032 return false;
6033 case Instruction::SDiv:
6034 case Instruction::UDiv:
6035 case Instruction::SRem:
6036 case Instruction::URem:
6037 return true;
6038 case Instruction::FDiv:
6039 case Instruction::FRem:
6040 return !Use->hasNoNaNs();
6041 }
6042 llvm_unreachable(nullptr)::llvm::llvm_unreachable_internal(nullptr, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 6042)
;
6043 }
6044
6045public:
6046 VectorPromoteHelper(const DataLayout &DL, const TargetLowering &TLI,
6047 const TargetTransformInfo &TTI, Instruction *Transition,
6048 unsigned CombineCost)
6049 : DL(DL), TLI(TLI), TTI(TTI), Transition(Transition),
6050 StoreExtractCombineCost(CombineCost) {
6051 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\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 6051, __PRETTY_FUNCTION__))
;
6052 }
6053
6054 /// \brief Check if we can promote \p ToBePromoted to \p Type.
6055 bool canPromote(const Instruction *ToBePromoted) const {
6056 // We could support CastInst too.
6057 return isa<BinaryOperator>(ToBePromoted);
6058 }
6059
6060 /// \brief Check if it is profitable to promote \p ToBePromoted
6061 /// by moving downward the transition through.
6062 bool shouldPromote(const Instruction *ToBePromoted) const {
6063 // Promote only if all the operands can be statically expanded.
6064 // Indeed, we do not want to introduce any new kind of transitions.
6065 for (const Use &U : ToBePromoted->operands()) {
6066 const Value *Val = U.get();
6067 if (Val == getEndOfTransition()) {
6068 // If the use is a division and the transition is on the rhs,
6069 // we cannot promote the operation, otherwise we may create a
6070 // division by zero.
6071 if (canCauseUndefinedBehavior(ToBePromoted, U.getOperandNo()))
6072 return false;
6073 continue;
6074 }
6075 if (!isa<ConstantInt>(Val) && !isa<UndefValue>(Val) &&
6076 !isa<ConstantFP>(Val))
6077 return false;
6078 }
6079 // Check that the resulting operation is legal.
6080 int ISDOpcode = TLI.InstructionOpcodeToISD(ToBePromoted->getOpcode());
6081 if (!ISDOpcode)
6082 return false;
6083 return StressStoreExtract ||
6084 TLI.isOperationLegalOrCustom(
6085 ISDOpcode, TLI.getValueType(DL, getTransitionType(), true));
6086 }
6087
6088 /// \brief Check whether or not \p Use can be combined
6089 /// with the transition.
6090 /// I.e., is it possible to do Use(Transition) => AnotherUse?
6091 bool canCombine(const Instruction *Use) { return isa<StoreInst>(Use); }
6092
6093 /// \brief Record \p ToBePromoted as part of the chain to be promoted.
6094 void enqueueForPromotion(Instruction *ToBePromoted) {
6095 InstsToBePromoted.push_back(ToBePromoted);
6096 }
6097
6098 /// \brief Set the instruction that will be combined with the transition.
6099 void recordCombineInstruction(Instruction *ToBeCombined) {
6100 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\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 6100, __PRETTY_FUNCTION__))
;
6101 CombineInst = ToBeCombined;
6102 }
6103
6104 /// \brief Promote all the instructions enqueued for promotion if it is
6105 /// is profitable.
6106 /// \return True if the promotion happened, false otherwise.
6107 bool promote() {
6108 // Check if there is something to promote.
6109 // Right now, if we do not have anything to combine with,
6110 // we assume the promotion is not profitable.
6111 if (InstsToBePromoted.empty() || !CombineInst)
6112 return false;
6113
6114 // Check cost.
6115 if (!StressStoreExtract && !isProfitableToPromote())
6116 return false;
6117
6118 // Promote.
6119 for (auto &ToBePromoted : InstsToBePromoted)
6120 promoteImpl(ToBePromoted);
6121 InstsToBePromoted.clear();
6122 return true;
6123 }
6124};
6125
6126} // end anonymous namespace
6127
6128void VectorPromoteHelper::promoteImpl(Instruction *ToBePromoted) {
6129 // At this point, we know that all the operands of ToBePromoted but Def
6130 // can be statically promoted.
6131 // For Def, we need to use its parameter in ToBePromoted:
6132 // b = ToBePromoted ty1 a
6133 // Def = Transition ty1 b to ty2
6134 // Move the transition down.
6135 // 1. Replace all uses of the promoted operation by the transition.
6136 // = ... b => = ... Def.
6137 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\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 6139, __PRETTY_FUNCTION__))
6138 "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\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 6139, __PRETTY_FUNCTION__))
6139 "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\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 6139, __PRETTY_FUNCTION__))
;
6140 ToBePromoted->replaceAllUsesWith(Transition);
6141 // 2. Update the type of the uses.
6142 // b = ToBePromoted ty2 Def => b = ToBePromoted ty1 Def.
6143 Type *TransitionTy = getTransitionType();
6144 ToBePromoted->mutateType(TransitionTy);
6145 // 3. Update all the operands of the promoted operation with promoted
6146 // operands.
6147 // b = ToBePromoted ty1 Def => b = ToBePromoted ty1 a.
6148 for (Use &U : ToBePromoted->operands()) {
6149 Value *Val = U.get();
6150 Value *NewVal = nullptr;
6151 if (Val == Transition)
6152 NewVal = Transition->getOperand(getTransitionOriginalValueIdx());
6153 else if (isa<UndefValue>(Val) || isa<ConstantInt>(Val) ||
6154 isa<ConstantFP>(Val)) {
6155 // Use a splat constant if it is not safe to use undef.
6156 NewVal = getConstantVector(
6157 cast<Constant>(Val),
6158 isa<UndefValue>(Val) ||
6159 canCauseUndefinedBehavior(ToBePromoted, U.getOperandNo()));
6160 } else
6161 llvm_unreachable("Did you modified shouldPromote and forgot to update "::llvm::llvm_unreachable_internal("Did you modified shouldPromote and forgot to update "
"this?", "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 6162)
6162 "this?")::llvm::llvm_unreachable_internal("Did you modified shouldPromote and forgot to update "
"this?", "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 6162)
;
6163 ToBePromoted->setOperand(U.getOperandNo(), NewVal);
6164 }
6165 Transition->moveAfter(ToBePromoted);
6166 Transition->setOperand(getTransitionOriginalValueIdx(), ToBePromoted);
6167}
6168
6169/// Some targets can do store(extractelement) with one instruction.
6170/// Try to push the extractelement towards the stores when the target
6171/// has this feature and this is profitable.
6172bool CodeGenPrepare::optimizeExtractElementInst(Instruction *Inst) {
6173 unsigned CombineCost = std::numeric_limits<unsigned>::max();
6174 if (DisableStoreExtract || !TLI ||
6175 (!StressStoreExtract &&
6176 !TLI->canCombineStoreAndExtract(Inst->getOperand(0)->getType(),
6177 Inst->getOperand(1), CombineCost)))
6178 return false;
6179
6180 // At this point we know that Inst is a vector to scalar transition.
6181 // Try to move it down the def-use chain, until:
6182 // - We can combine the transition with its single use
6183 // => we got rid of the transition.
6184 // - We escape the current basic block
6185 // => we would need to check that we are moving it at a cheaper place and
6186 // we do not do that for now.
6187 BasicBlock *Parent = Inst->getParent();
6188 DEBUG(dbgs() << "Found an interesting transition: " << *Inst << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Found an interesting transition: "
<< *Inst << '\n'; } } while (false)
;
6189 VectorPromoteHelper VPH(*DL, *TLI, *TTI, Inst, CombineCost);
6190 // If the transition has more than one use, assume this is not going to be
6191 // beneficial.
6192 while (Inst->hasOneUse()) {
6193 Instruction *ToBePromoted = cast<Instruction>(*Inst->user_begin());
6194 DEBUG(dbgs() << "Use: " << *ToBePromoted << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Use: " << *ToBePromoted
<< '\n'; } } while (false)
;
6195
6196 if (ToBePromoted->getParent() != Parent) {
6197 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)
6198 << 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)
6199 << ") 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)
;
6200 return false;
6201 }
6202
6203 if (VPH.canCombine(ToBePromoted)) {
6204 DEBUG(dbgs() << "Assume " << *Inst << '\n'do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Assume " << *Inst
<< '\n' << "will be combined with: " << *ToBePromoted
<< '\n'; } } while (false)
6205 << "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)
;
6206 VPH.recordCombineInstruction(ToBePromoted);
6207 bool Changed = VPH.promote();
6208 NumStoreExtractExposed += Changed;
6209 return Changed;
6210 }
6211
6212 DEBUG(dbgs() << "Try promoting.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Try promoting.\n"; } }
while (false)
;
6213 if (!VPH.canPromote(ToBePromoted) || !VPH.shouldPromote(ToBePromoted))
6214 return false;
6215
6216 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)
;
6217
6218 VPH.enqueueForPromotion(ToBePromoted);
6219 Inst = ToBePromoted;
6220 }
6221 return false;
6222}
6223
6224/// For the instruction sequence of store below, F and I values
6225/// are bundled together as an i64 value before being stored into memory.
6226/// Sometimes it is more efficent to generate separate stores for F and I,
6227/// which can remove the bitwise instructions or sink them to colder places.
6228///
6229/// (store (or (zext (bitcast F to i32) to i64),
6230/// (shl (zext I to i64), 32)), addr) -->
6231/// (store F, addr) and (store I, addr+4)
6232///
6233/// Similarly, splitting for other merged store can also be beneficial, like:
6234/// For pair of {i32, i32}, i64 store --> two i32 stores.
6235/// For pair of {i32, i16}, i64 store --> two i32 stores.
6236/// For pair of {i16, i16}, i32 store --> two i16 stores.
6237/// For pair of {i16, i8}, i32 store --> two i16 stores.
6238/// For pair of {i8, i8}, i16 store --> two i8 stores.
6239///
6240/// We allow each target to determine specifically which kind of splitting is
6241/// supported.
6242///
6243/// The store patterns are commonly seen from the simple code snippet below
6244/// if only std::make_pair(...) is sroa transformed before inlined into hoo.
6245/// void goo(const std::pair<int, float> &);
6246/// hoo() {
6247/// ...
6248/// goo(std::make_pair(tmp, ftmp));
6249/// ...
6250/// }
6251///
6252/// Although we already have similar splitting in DAG Combine, we duplicate
6253/// it in CodeGenPrepare to catch the case in which pattern is across
6254/// multiple BBs. The logic in DAG Combine is kept to catch case generated
6255/// during code expansion.
6256static bool splitMergedValStore(StoreInst &SI, const DataLayout &DL,
6257 const TargetLowering &TLI) {
6258 // Handle simple but common cases only.
6259 Type *StoreType = SI.getValueOperand()->getType();
6260 if (DL.getTypeStoreSizeInBits(StoreType) != DL.getTypeSizeInBits(StoreType) ||
6261 DL.getTypeSizeInBits(StoreType) == 0)
6262 return false;
6263
6264 unsigned HalfValBitSize = DL.getTypeSizeInBits(StoreType) / 2;
6265 Type *SplitStoreType = Type::getIntNTy(SI.getContext(), HalfValBitSize);
6266 if (DL.getTypeStoreSizeInBits(SplitStoreType) !=
6267 DL.getTypeSizeInBits(SplitStoreType))
6268 return false;
6269
6270 // Match the following patterns:
6271 // (store (or (zext LValue to i64),
6272 // (shl (zext HValue to i64), 32)), HalfValBitSize)
6273 // or
6274 // (store (or (shl (zext HValue to i64), 32)), HalfValBitSize)
6275 // (zext LValue to i64),
6276 // Expect both operands of OR and the first operand of SHL have only
6277 // one use.
6278 Value *LValue, *HValue;
6279 if (!match(SI.getValueOperand(),
6280 m_c_Or(m_OneUse(m_ZExt(m_Value(LValue))),
6281 m_OneUse(m_Shl(m_OneUse(m_ZExt(m_Value(HValue))),
6282 m_SpecificInt(HalfValBitSize))))))
6283 return false;
6284
6285 // Check LValue and HValue are int with size less or equal than 32.
6286 if (!LValue->getType()->isIntegerTy() ||
6287 DL.getTypeSizeInBits(LValue->getType()) > HalfValBitSize ||
6288 !HValue->getType()->isIntegerTy() ||
6289 DL.getTypeSizeInBits(HValue->getType()) > HalfValBitSize)
6290 return false;
6291
6292 // If LValue/HValue is a bitcast instruction, use the EVT before bitcast
6293 // as the input of target query.
6294 auto *LBC = dyn_cast<BitCastInst>(LValue);
6295 auto *HBC = dyn_cast<BitCastInst>(HValue);
6296 EVT LowTy = LBC ? EVT::getEVT(LBC->getOperand(0)->getType())
6297 : EVT::getEVT(LValue->getType());
6298 EVT HighTy = HBC ? EVT::getEVT(HBC->getOperand(0)->getType())
6299 : EVT::getEVT(HValue->getType());
6300 if (!ForceSplitStore && !TLI.isMultiStoresCheaperThanBitsMerge(LowTy, HighTy))
6301 return false;
6302
6303 // Start to split store.
6304 IRBuilder<> Builder(SI.getContext());
6305 Builder.SetInsertPoint(&SI);
6306
6307 // If LValue/HValue is a bitcast in another BB, create a new one in current
6308 // BB so it may be merged with the splitted stores by dag combiner.
6309 if (LBC && LBC->getParent() != SI.getParent())
6310 LValue = Builder.CreateBitCast(LBC->getOperand(0), LBC->getType());
6311 if (HBC && HBC->getParent() != SI.getParent())
6312 HValue = Builder.CreateBitCast(HBC->getOperand(0), HBC->getType());
6313
6314 auto CreateSplitStore = [&](Value *V, bool Upper) {
6315 V = Builder.CreateZExtOrBitCast(V, SplitStoreType);
6316 Value *Addr = Builder.CreateBitCast(
6317 SI.getOperand(1),
6318 SplitStoreType->getPointerTo(SI.getPointerAddressSpace()));
6319 if (Upper)
6320 Addr = Builder.CreateGEP(
6321 SplitStoreType, Addr,
6322 ConstantInt::get(Type::getInt32Ty(SI.getContext()), 1));
6323 Builder.CreateAlignedStore(
6324 V, Addr, Upper ? SI.getAlignment() / 2 : SI.getAlignment());
6325 };
6326
6327 CreateSplitStore(LValue, false);
6328 CreateSplitStore(HValue, true);
6329
6330 // Delete the old store.
6331 SI.eraseFromParent();
6332 return true;
6333}
6334
6335// Return true if the GEP has two operands, the first operand is of a sequential
6336// type, and the second operand is a constant.
6337static bool GEPSequentialConstIndexed(GetElementPtrInst *GEP) {
6338 gep_type_iterator I = gep_type_begin(*GEP);
6339 return GEP->getNumOperands() == 2 &&
6340 I.isSequential() &&
6341 isa<ConstantInt>(GEP->getOperand(1));
6342}
6343
6344// Try unmerging GEPs to reduce liveness interference (register pressure) across
6345// IndirectBr edges. Since IndirectBr edges tend to touch on many blocks,
6346// reducing liveness interference across those edges benefits global register
6347// allocation. Currently handles only certain cases.
6348//
6349// For example, unmerge %GEPI and %UGEPI as below.
6350//
6351// ---------- BEFORE ----------
6352// SrcBlock:
6353// ...
6354// %GEPIOp = ...
6355// ...
6356// %GEPI = gep %GEPIOp, Idx
6357// ...
6358// indirectbr ... [ label %DstB0, label %DstB1, ... label %DstBi ... ]
6359// (* %GEPI is alive on the indirectbr edges due to other uses ahead)
6360// (* %GEPIOp is alive on the indirectbr edges only because of it's used by
6361// %UGEPI)
6362//
6363// DstB0: ... (there may be a gep similar to %UGEPI to be unmerged)
6364// DstB1: ... (there may be a gep similar to %UGEPI to be unmerged)
6365// ...
6366//
6367// DstBi:
6368// ...
6369// %UGEPI = gep %GEPIOp, UIdx
6370// ...
6371// ---------------------------
6372//
6373// ---------- AFTER ----------
6374// SrcBlock:
6375// ... (same as above)
6376// (* %GEPI is still alive on the indirectbr edges)
6377// (* %GEPIOp is no longer alive on the indirectbr edges as a result of the
6378// unmerging)
6379// ...
6380//
6381// DstBi:
6382// ...
6383// %UGEPI = gep %GEPI, (UIdx-Idx)
6384// ...
6385// ---------------------------
6386//
6387// The register pressure on the IndirectBr edges is reduced because %GEPIOp is
6388// no longer alive on them.
6389//
6390// We try to unmerge GEPs here in CodGenPrepare, as opposed to limiting merging
6391// of GEPs in the first place in InstCombiner::visitGetElementPtrInst() so as
6392// not to disable further simplications and optimizations as a result of GEP
6393// merging.
6394//
6395// Note this unmerging may increase the length of the data flow critical path
6396// (the path from %GEPIOp to %UGEPI would go through %GEPI), which is a tradeoff
6397// between the register pressure and the length of data-flow critical
6398// path. Restricting this to the uncommon IndirectBr case would minimize the
6399// impact of potentially longer critical path, if any, and the impact on compile
6400// time.
6401static bool tryUnmergingGEPsAcrossIndirectBr(GetElementPtrInst *GEPI,
6402 const TargetTransformInfo *TTI) {
6403 BasicBlock *SrcBlock = GEPI->getParent();
6404 // Check that SrcBlock ends with an IndirectBr. If not, give up. The common
6405 // (non-IndirectBr) cases exit early here.
6406 if (!isa<IndirectBrInst>(SrcBlock->getTerminator()))
6407 return false;
6408 // Check that GEPI is a simple gep with a single constant index.
6409 if (!GEPSequentialConstIndexed(GEPI))
6410 return false;
6411 ConstantInt *GEPIIdx = cast<ConstantInt>(GEPI->getOperand(1));
6412 // Check that GEPI is a cheap one.
6413 if (TTI->getIntImmCost(GEPIIdx->getValue(), GEPIIdx->getType())
6414 > TargetTransformInfo::TCC_Basic)
6415 return false;
6416 Value *GEPIOp = GEPI->getOperand(0);
6417 // Check that GEPIOp is an instruction that's also defined in SrcBlock.
6418 if (!isa<Instruction>(GEPIOp))
6419 return false;
6420 auto *GEPIOpI = cast<Instruction>(GEPIOp);
6421 if (GEPIOpI->getParent() != SrcBlock)
6422 return false;
6423 // Check that GEP is used outside the block, meaning it's alive on the
6424 // IndirectBr edge(s).
6425 if (find_if(GEPI->users(), [&](User *Usr) {
6426 if (auto *I = dyn_cast<Instruction>(Usr)) {
6427 if (I->getParent() != SrcBlock) {
6428 return true;
6429 }
6430 }
6431 return false;
6432 }) == GEPI->users().end())
6433 return false;
6434 // The second elements of the GEP chains to be unmerged.
6435 std::vector<GetElementPtrInst *> UGEPIs;
6436 // Check each user of GEPIOp to check if unmerging would make GEPIOp not alive
6437 // on IndirectBr edges.
6438 for (User *Usr : GEPIOp->users()) {
6439 if (Usr == GEPI) continue;
6440 // Check if Usr is an Instruction. If not, give up.
6441 if (!isa<Instruction>(Usr))
6442 return false;
6443 auto *UI = cast<Instruction>(Usr);
6444 // Check if Usr in the same block as GEPIOp, which is fine, skip.
6445 if (UI->getParent() == SrcBlock)
6446 continue;
6447 // Check if Usr is a GEP. If not, give up.
6448 if (!isa<GetElementPtrInst>(Usr))
6449 return false;
6450 auto *UGEPI = cast<GetElementPtrInst>(Usr);
6451 // Check if UGEPI is a simple gep with a single constant index and GEPIOp is
6452 // the pointer operand to it. If so, record it in the vector. If not, give
6453 // up.
6454 if (!GEPSequentialConstIndexed(UGEPI))
6455 return false;
6456 if (UGEPI->getOperand(0) != GEPIOp)
6457 return false;
6458 if (GEPIIdx->getType() !=
6459 cast<ConstantInt>(UGEPI->getOperand(1))->getType())
6460 return false;
6461 ConstantInt *UGEPIIdx = cast<ConstantInt>(UGEPI->getOperand(1));
6462 if (TTI->getIntImmCost(UGEPIIdx->getValue(), UGEPIIdx->getType())
6463 > TargetTransformInfo::TCC_Basic)
6464 return false;
6465 UGEPIs.push_back(UGEPI);
6466 }
6467 if (UGEPIs.size() == 0)
6468 return false;
6469 // Check the materializing cost of (Uidx-Idx).
6470 for (GetElementPtrInst *UGEPI : UGEPIs) {
6471 ConstantInt *UGEPIIdx = cast<ConstantInt>(UGEPI->getOperand(1));
6472 APInt NewIdx = UGEPIIdx->getValue() - GEPIIdx->getValue();
6473 unsigned ImmCost = TTI->getIntImmCost(NewIdx, GEPIIdx->getType());
6474 if (ImmCost > TargetTransformInfo::TCC_Basic)
6475 return false;
6476 }
6477 // Now unmerge between GEPI and UGEPIs.
6478 for (GetElementPtrInst *UGEPI : UGEPIs) {
6479 UGEPI->setOperand(0, GEPI);
6480 ConstantInt *UGEPIIdx = cast<ConstantInt>(UGEPI->getOperand(1));
6481 Constant *NewUGEPIIdx =
6482 ConstantInt::get(GEPIIdx->getType(),
6483 UGEPIIdx->getValue() - GEPIIdx->getValue());
6484 UGEPI->setOperand(1, NewUGEPIIdx);
6485 // If GEPI is not inbounds but UGEPI is inbounds, change UGEPI to not
6486 // inbounds to avoid UB.
6487 if (!GEPI->isInBounds()) {
6488 UGEPI->setIsInBounds(false);
6489 }
6490 }
6491 // After unmerging, verify that GEPIOp is actually only used in SrcBlock (not
6492 // alive on IndirectBr edges).
6493 assert(find_if(GEPIOp->users(), [&](User *Usr) {((find_if(GEPIOp->users(), [&](User *Usr) { return cast
<Instruction>(Usr)->getParent() != SrcBlock; }) == GEPIOp
->users().end() && "GEPIOp is used outside SrcBlock"
) ? static_cast<void> (0) : __assert_fail ("find_if(GEPIOp->users(), [&](User *Usr) { return cast<Instruction>(Usr)->getParent() != SrcBlock; }) == GEPIOp->users().end() && \"GEPIOp is used outside SrcBlock\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 6495, __PRETTY_FUNCTION__))
6494 return cast<Instruction>(Usr)->getParent() != SrcBlock;((find_if(GEPIOp->users(), [&](User *Usr) { return cast
<Instruction>(Usr)->getParent() != SrcBlock; }) == GEPIOp
->users().end() && "GEPIOp is used outside SrcBlock"
) ? static_cast<void> (0) : __assert_fail ("find_if(GEPIOp->users(), [&](User *Usr) { return cast<Instruction>(Usr)->getParent() != SrcBlock; }) == GEPIOp->users().end() && \"GEPIOp is used outside SrcBlock\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 6495, __PRETTY_FUNCTION__))
6495 }) == GEPIOp->users().end() && "GEPIOp is used outside SrcBlock")((find_if(GEPIOp->users(), [&](User *Usr) { return cast
<Instruction>(Usr)->getParent() != SrcBlock; }) == GEPIOp
->users().end() && "GEPIOp is used outside SrcBlock"
) ? static_cast<void> (0) : __assert_fail ("find_if(GEPIOp->users(), [&](User *Usr) { return cast<Instruction>(Usr)->getParent() != SrcBlock; }) == GEPIOp->users().end() && \"GEPIOp is used outside SrcBlock\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/CodeGen/CodeGenPrepare.cpp"
, 6495, __PRETTY_FUNCTION__))
;
6496 return true;
6497}
6498
6499bool CodeGenPrepare::optimizeInst(Instruction *I, bool &ModifiedDT) {
6500 // Bail out if we inserted the instruction to prevent optimizations from
6501 // stepping on each other's toes.
6502 if (InsertedInsts.count(I))
6503 return false;
6504
6505 if (PHINode *P = dyn_cast<PHINode>(I)) {
6506 // It is possible for very late stage optimizations (such as SimplifyCFG)
6507 // to introduce PHI nodes too late to be cleaned up. If we detect such a
6508 // trivial PHI, go ahead and zap it here.
6509 if (Value *V = SimplifyInstruction(P, {*DL, TLInfo})) {
6510 P->replaceAllUsesWith(V);
6511 P->eraseFromParent();
6512 ++NumPHIsElim;
6513 return true;
6514 }
6515 return false;
6516 }
6517
6518 if (CastInst *CI = dyn_cast<CastInst>(I)) {
6519 // If the source of the cast is a constant, then this should have
6520 // already been constant folded. The only reason NOT to constant fold
6521 // it is if something (e.g. LSR) was careful to place the constant
6522 // evaluation in a block other than then one that uses it (e.g. to hoist
6523 // the address of globals out of a loop). If this is the case, we don't
6524 // want to forward-subst the cast.
6525 if (isa<Constant>(CI->getOperand(0)))
6526 return false;
6527
6528 if (TLI && OptimizeNoopCopyExpression(CI, *TLI, *DL))
6529 return true;
6530
6531 if (isa<ZExtInst>(I) || isa<SExtInst>(I)) {
6532 /// Sink a zext or sext into its user blocks if the target type doesn't
6533 /// fit in one register
6534 if (TLI &&
6535 TLI->getTypeAction(CI->getContext(),
6536 TLI->getValueType(*DL, CI->getType())) ==
6537 TargetLowering::TypeExpandInteger) {
6538 return SinkCast(CI);
6539 } else {
6540 bool MadeChange = optimizeExt(I);
6541 return MadeChange | optimizeExtUses(I);
6542 }
6543 }
6544 return false;
6545 }
6546
6547 if (CmpInst *CI = dyn_cast<CmpInst>(I))
6548 if (!TLI || !TLI->hasMultipleConditionRegisters())
6549 return OptimizeCmpExpression(CI, TLI);
6550
6551 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
6552 LI->setMetadata(LLVMContext::MD_invariant_group, nullptr);
6553 if (TLI) {
6554 bool Modified = optimizeLoadExt(LI);
6555 unsigned AS = LI->getPointerAddressSpace();
6556 Modified |= optimizeMemoryInst(I, I->getOperand(0), LI->getType(), AS);
6557 return Modified;
6558 }
6559 return false;
6560 }
6561
6562 if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
6563 if (TLI && splitMergedValStore(*SI, *DL, *TLI))
6564 return true;
6565 SI->setMetadata(LLVMContext::MD_invariant_group, nullptr);
6566 if (TLI) {
6567 unsigned AS = SI->getPointerAddressSpace();
6568 return optimizeMemoryInst(I, SI->getOperand(1),
6569 SI->getOperand(0)->getType(), AS);
6570 }
6571 return false;
6572 }
6573
6574 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
6575 unsigned AS = RMW->getPointerAddressSpace();
6576 return optimizeMemoryInst(I, RMW->getPointerOperand(),
6577 RMW->getType(), AS);
6578 }
6579
6580 if (AtomicCmpXchgInst *CmpX = dyn_cast<AtomicCmpXchgInst>(I)) {
6581 unsigned AS = CmpX->getPointerAddressSpace();
6582 return optimizeMemoryInst(I, CmpX->getPointerOperand(),
6583 CmpX->getCompareOperand()->getType(), AS);
6584 }
6585
6586 BinaryOperator *BinOp = dyn_cast<BinaryOperator>(I);
6587
6588 if (BinOp && (BinOp->getOpcode() == Instruction::And) &&
6589 EnableAndCmpSinking && TLI)
6590 return sinkAndCmp0Expression(BinOp, *TLI, InsertedInsts);
6591
6592 if (BinOp && (BinOp->getOpcode() == Instruction::AShr ||
6593 BinOp->getOpcode() == Instruction::LShr)) {
6594 ConstantInt *CI = dyn_cast<ConstantInt>(BinOp->getOperand(1));
6595 if (TLI && CI && TLI->hasExtractBitsInsn())
6596 return OptimizeExtractBits(BinOp, CI, *TLI, *DL);
6597
6598 return false;
6599 }
6600
6601 if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(I)) {
6602 if (GEPI->hasAllZeroIndices()) {
6603 /// The GEP operand must be a pointer, so must its result -> BitCast
6604 Instruction *NC = new BitCastInst(GEPI->getOperand(0), GEPI->getType(),
6605 GEPI->getName(), GEPI);
6606 GEPI->replaceAllUsesWith(NC);
6607 GEPI->eraseFromParent();
6608 ++NumGEPsElim;
6609 optimizeInst(NC, ModifiedDT);
6610 return true;
6611 }
6612 if (tryUnmergingGEPsAcrossIndirectBr(GEPI, TTI)) {
6613 return true;
6614 }
6615 return false;
6616 }
6617
6618 if (CallInst *CI = dyn_cast<CallInst>(I))
6619 return optimizeCallInst(CI, ModifiedDT);
6620
6621 if (SelectInst *SI = dyn_cast<SelectInst>(I))
6622 return optimizeSelectInst(SI);
6623
6624 if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(I))
6625 return optimizeShuffleVectorInst(SVI);
6626
6627 if (auto *Switch = dyn_cast<SwitchInst>(I))
6628 return optimizeSwitchInst(Switch);
6629
6630 if (isa<ExtractElementInst>(I))
6631 return optimizeExtractElementInst(I);
6632
6633 return false;
6634}
6635
6636/// Given an OR instruction, check to see if this is a bitreverse
6637/// idiom. If so, insert the new intrinsic and return true.
6638static bool makeBitReverse(Instruction &I, const DataLayout &DL,
6639 const TargetLowering &TLI) {
6640 if (!I.getType()->isIntegerTy() ||
6641 !TLI.isOperationLegalOrCustom(ISD::BITREVERSE,
6642 TLI.getValueType(DL, I.getType(), true)))
6643 return false;
6644
6645 SmallVector<Instruction*, 4> Insts;
6646 if (!recognizeBSwapOrBitReverseIdiom(&I, false, true, Insts))
6647 return false;
6648 Instruction *LastInst = Insts.back();
6649 I.replaceAllUsesWith(LastInst);
6650 RecursivelyDeleteTriviallyDeadInstructions(&I);
6651 return true;
6652}
6653
6654// In this pass we look for GEP and cast instructions that are used
6655// across basic blocks and rewrite them to improve basic-block-at-a-time
6656// selection.
6657bool CodeGenPrepare::optimizeBlock(BasicBlock &BB, bool &ModifiedDT) {
6658 SunkAddrs.clear();
6659 bool MadeChange = false;
6660
6661 CurInstIterator = BB.begin();
6662 while (CurInstIterator != BB.end()) {
6663 MadeChange |= optimizeInst(&*CurInstIterator++, ModifiedDT);
6664 if (ModifiedDT)
6665 return true;
6666 }
6667
6668 bool MadeBitReverse = true;
6669 while (TLI && MadeBitReverse) {
6670 MadeBitReverse = false;
6671 for (auto &I : reverse(BB)) {
6672 if (makeBitReverse(I, *DL, *TLI)) {
6673 MadeBitReverse = MadeChange = true;
6674 ModifiedDT = true;
6675 break;
6676 }
6677 }
6678 }
6679 MadeChange |= dupRetToEnableTailCallOpts(&BB);
6680
6681 return MadeChange;
6682}
6683
6684// llvm.dbg.value is far away from the value then iSel may not be able
6685// handle it properly. iSel will drop llvm.dbg.value if it can not
6686// find a node corresponding to the value.
6687bool CodeGenPrepare::placeDbgValues(Function &F) {
6688 bool MadeChange = false;
6689 for (BasicBlock &BB : F) {
6690 Instruction *PrevNonDbgInst = nullptr;
6691 for (BasicBlock::iterator BI = BB.begin(), BE = BB.end(); BI != BE;) {
6692 Instruction *Insn = &*BI++;
6693 DbgValueInst *DVI = dyn_cast<DbgValueInst>(Insn);
6694 // Leave dbg.values that refer to an alloca alone. These
6695 // instrinsics describe the address of a variable (= the alloca)
6696 // being taken. They should not be moved next to the alloca
6697 // (and to the beginning of the scope), but rather stay close to
6698 // where said address is used.
6699 if (!DVI || (DVI->getValue() && isa<AllocaInst>(DVI->getValue()))) {
6700 PrevNonDbgInst = Insn;
6701 continue;
6702 }
6703
6704 Instruction *VI = dyn_cast_or_null<Instruction>(DVI->getValue());
6705 if (VI && VI != PrevNonDbgInst && !VI->isTerminator()) {
6706 // If VI is a phi in a block with an EHPad terminator, we can't insert
6707 // after it.
6708 if (isa<PHINode>(VI) && VI->getParent()->getTerminator()->isEHPad())
6709 continue;
6710 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)
;
6711 DVI->removeFromParent();
6712 if (isa<PHINode>(VI))
6713 DVI->insertBefore(&*VI->getParent()->getFirstInsertionPt());
6714 else
6715 DVI->insertAfter(VI);
6716 MadeChange = true;
6717 ++NumDbgValueMoved;
6718 }
6719 }
6720 }
6721 return MadeChange;
6722}
6723
6724/// \brief Scale down both weights to fit into uint32_t.
6725static void scaleWeights(uint64_t &NewTrue, uint64_t &NewFalse) {
6726 uint64_t NewMax = (NewTrue > NewFalse) ? NewTrue : NewFalse;
6727 uint32_t Scale = (NewMax / std::numeric_limits<uint32_t>::max()) + 1;
6728 NewTrue = NewTrue / Scale;
6729 NewFalse = NewFalse / Scale;
6730}
6731
6732/// \brief Some targets prefer to split a conditional branch like:
6733/// \code
6734/// %0 = icmp ne i32 %a, 0
6735/// %1 = icmp ne i32 %b, 0
6736/// %or.cond = or i1 %0, %1
6737/// br i1 %or.cond, label %TrueBB, label %FalseBB
6738/// \endcode
6739/// into multiple branch instructions like:
6740/// \code
6741/// bb1:
6742/// %0 = icmp ne i32 %a, 0
6743/// br i1 %0, label %TrueBB, label %bb2
6744/// bb2:
6745/// %1 = icmp ne i32 %b, 0
6746/// br i1 %1, label %TrueBB, label %FalseBB
6747/// \endcode
6748/// This usually allows instruction selection to do even further optimizations
6749/// and combine the compare with the branch instruction. Currently this is
6750/// applied for targets which have "cheap" jump instructions.
6751///
6752/// FIXME: Remove the (equivalent?) implementation in SelectionDAG.
6753///
6754bool CodeGenPrepare::splitBranchCondition(Function &F) {
6755 if (!TM || !TM->Options.EnableFastISel || !TLI || TLI->isJumpExpensive())
6756 return false;
6757
6758 bool MadeChange = false;
6759 for (auto &BB : F) {
6760 // Does this BB end with the following?
6761 // %cond1 = icmp|fcmp|binary instruction ...
6762 // %cond2 = icmp|fcmp|binary instruction ...
6763 // %cond.or = or|and i1 %cond1, cond2
6764 // br i1 %cond.or label %dest1, label %dest2"
6765 BinaryOperator *LogicOp;
6766 BasicBlock *TBB, *FBB;
6767 if (!match(BB.getTerminator(), m_Br(m_OneUse(m_BinOp(LogicOp)), TBB, FBB)))
6768 continue;
6769
6770 auto *Br1 = cast<BranchInst>(BB.getTerminator());
6771 if (Br1->getMetadata(LLVMContext::MD_unpredictable))
6772 continue;
6773
6774 unsigned Opc;
6775 Value *Cond1, *Cond2;
6776 if (match(LogicOp, m_And(m_OneUse(m_Value(Cond1)),
6777 m_OneUse(m_Value(Cond2)))))
6778 Opc = Instruction::And;
6779 else if (match(LogicOp, m_Or(m_OneUse(m_Value(Cond1)),
6780 m_OneUse(m_Value(Cond2)))))
6781 Opc = Instruction::Or;
6782 else
6783 continue;
6784
6785 if (!match(Cond1, m_CombineOr(m_Cmp(), m_BinOp())) ||
6786 !match(Cond2, m_CombineOr(m_Cmp(), m_BinOp())) )
6787 continue;
6788
6789 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)
;
6790
6791 // Create a new BB.
6792 auto TmpBB =
6793 BasicBlock::Create(BB.getContext(), BB.getName() + ".cond.split",
6794 BB.getParent(), BB.getNextNode());
6795
6796 // Update original basic block by using the first condition directly by the
6797 // branch instruction and removing the no longer needed and/or instruction.
6798 Br1->setCondition(Cond1);
6799 LogicOp->eraseFromParent();
6800
6801 // Depending on the conditon we have to either replace the true or the false
6802 // successor of the original branch instruction.
6803 if (Opc == Instruction::And)
6804 Br1->setSuccessor(0, TmpBB);
6805 else
6806 Br1->setSuccessor(1, TmpBB);
6807
6808 // Fill in the new basic block.
6809 auto *Br2 = IRBuilder<>(TmpBB).CreateCondBr(Cond2, TBB, FBB);
6810 if (auto *I = dyn_cast<Instruction>(Cond2)) {
6811 I->removeFromParent();
6812 I->insertBefore(Br2);
6813 }
6814
6815 // Update PHI nodes in both successors. The original BB needs to be
6816 // replaced in one successor's PHI nodes, because the branch comes now from
6817 // the newly generated BB (NewBB). In the other successor we need to add one
6818 // incoming edge to the PHI nodes, because both branch instructions target
6819 // now the same successor. Depending on the original branch condition
6820 // (and/or) we have to swap the successors (TrueDest, FalseDest), so that
6821 // we perform the correct update for the PHI nodes.
6822 // This doesn't change the successor order of the just created branch
6823 // instruction (or any other instruction).
6824 if (Opc == Instruction::Or)
6825 std::swap(TBB, FBB);
6826
6827 // Replace the old BB with the new BB.
6828 for (auto &I : *TBB) {
6829 PHINode *PN = dyn_cast<PHINode>(&I);
6830 if (!PN)
6831 break;
6832 int i;
6833 while ((i = PN->getBasicBlockIndex(&BB)) >= 0)
6834 PN->setIncomingBlock(i, TmpBB);
6835 }
6836
6837 // Add another incoming edge form the new BB.
6838 for (auto &I : *FBB) {
6839 PHINode *PN = dyn_cast<PHINode>(&I);
6840 if (!PN)
6841 break;
6842 auto *Val = PN->getIncomingValueForBlock(&BB);
6843 PN->addIncoming(Val, TmpBB);
6844 }
6845
6846 // Update the branch weights (from SelectionDAGBuilder::
6847 // FindMergedConditions).
6848 if (Opc == Instruction::Or) {
6849 // Codegen X | Y as:
6850 // BB1:
6851 // jmp_if_X TBB
6852 // jmp TmpBB
6853 // TmpBB:
6854 // jmp_if_Y TBB
6855 // jmp FBB
6856 //
6857
6858 // We have flexibility in setting Prob for BB1 and Prob for NewBB.
6859 // The requirement is that
6860 // TrueProb for BB1 + (FalseProb for BB1 * TrueProb for TmpBB)
6861 // = TrueProb for orignal BB.
6862 // Assuming the orignal weights are A and B, one choice is to set BB1's
6863 // weights to A and A+2B, and set TmpBB's weights to A and 2B. This choice
6864 // assumes that
6865 // TrueProb for BB1 == FalseProb for BB1 * TrueProb for TmpBB.
6866 // Another choice is to assume TrueProb for BB1 equals to TrueProb for
6867 // TmpBB, but the math is more complicated.
6868 uint64_t TrueWeight, FalseWeight;
6869 if (Br1->extractProfMetadata(TrueWeight, FalseWeight)) {
6870 uint64_t NewTrueWeight = TrueWeight;
6871 uint64_t NewFalseWeight = TrueWeight + 2 * FalseWeight;
6872 scaleWeights(NewTrueWeight, NewFalseWeight);
6873 Br1->setMetadata(LLVMContext::MD_prof, MDBuilder(Br1->getContext())
6874 .createBranchWeights(TrueWeight, FalseWeight));
6875
6876 NewTrueWeight = TrueWeight;
6877 NewFalseWeight = 2 * FalseWeight;
6878 scaleWeights(NewTrueWeight, NewFalseWeight);
6879 Br2->setMetadata(LLVMContext::MD_prof, MDBuilder(Br2->getContext())
6880 .createBranchWeights(TrueWeight, FalseWeight));
6881 }
6882 } else {
6883 // Codegen X & Y as:
6884 // BB1:
6885 // jmp_if_X TmpBB
6886 // jmp FBB
6887 // TmpBB:
6888 // jmp_if_Y TBB
6889 // jmp FBB
6890 //
6891 // This requires creation of TmpBB after CurBB.
6892
6893 // We have flexibility in setting Prob for BB1 and Prob for TmpBB.
6894 // The requirement is that
6895 // FalseProb for BB1 + (TrueProb for BB1 * FalseProb for TmpBB)
6896 // = FalseProb for orignal BB.
6897 // Assuming the orignal weights are A and B, one choice is to set BB1's
6898 // weights to 2A+B and B, and set TmpBB's weights to 2A and B. This choice
6899 // assumes that
6900 // FalseProb for BB1 == TrueProb for BB1 * FalseProb for TmpBB.
6901 uint64_t TrueWeight, FalseWeight;
6902 if (Br1->extractProfMetadata(TrueWeight, FalseWeight)) {
6903 uint64_t NewTrueWeight = 2 * TrueWeight + FalseWeight;
6904 uint64_t NewFalseWeight = FalseWeight;
6905 scaleWeights(NewTrueWeight, NewFalseWeight);
6906 Br1->setMetadata(LLVMContext::MD_prof, MDBuilder(Br1->getContext())
6907 .createBranchWeights(TrueWeight, FalseWeight));
6908
6909 NewTrueWeight = 2 * TrueWeight;
6910 NewFalseWeight = FalseWeight;
6911 scaleWeights(NewTrueWeight, NewFalseWeight);
6912 Br2->setMetadata(LLVMContext::MD_prof, MDBuilder(Br2->getContext())
6913 .createBranchWeights(TrueWeight, FalseWeight));
6914 }
6915 }
6916
6917 // Note: No point in getting fancy here, since the DT info is never
6918 // available to CodeGenPrepare.
6919 ModifiedDT = true;
6920
6921 MadeChange = true;
6922
6923 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)
6924 TmpBB->dump())do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "After branch condition splitting\n"
; BB.dump(); TmpBB->dump(); } } while (false)
;
6925 }
6926 return MadeChange;
6927}