Bug Summary

File:llvm/lib/CodeGen/CodeGenPrepare.cpp
Warning:line 1008, column 37
Called C++ object pointer is null

Annotated Source Code

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clang -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name CodeGenPrepare.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -analyzer-config-compatibility-mode=true -mrelocation-model pic -pic-level 2 -mthread-model posix -mframe-pointer=none -fmath-errno -fno-rounding-math -masm-verbose -mconstructor-aliases -munwind-tables -fuse-init-array -target-cpu x86-64 -dwarf-column-info -debugger-tuning=gdb -ffunction-sections -fdata-sections -resource-dir /usr/lib/llvm-10/lib/clang/10.0.0 -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-10~+201911111502510600c19528f1809/build-llvm/lib/CodeGen -I /build/llvm-toolchain-snapshot-10~+201911111502510600c19528f1809/llvm/lib/CodeGen -I /build/llvm-toolchain-snapshot-10~+201911111502510600c19528f1809/build-llvm/include -I /build/llvm-toolchain-snapshot-10~+201911111502510600c19528f1809/llvm/include -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/x86_64-linux-gnu/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/x86_64-linux-gnu/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0/backward -internal-isystem /usr/local/include -internal-isystem /usr/lib/llvm-10/lib/clang/10.0.0/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-comment -std=c++14 -fdeprecated-macro -fdebug-compilation-dir /build/llvm-toolchain-snapshot-10~+201911111502510600c19528f1809/build-llvm/lib/CodeGen -fdebug-prefix-map=/build/llvm-toolchain-snapshot-10~+201911111502510600c19528f1809=. -ferror-limit 19 -fmessage-length 0 -fvisibility-inlines-hidden -stack-protector 2 -fgnuc-version=4.2.1 -fobjc-runtime=gcc -fdiagnostics-show-option -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -faddrsig -o /tmp/scan-build-2019-12-09-002921-48462-1 -x c++ /build/llvm-toolchain-snapshot-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp
1//===- CodeGenPrepare.cpp - Prepare a function for code generation --------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This pass munges the code in the input function to better prepare it for
10// SelectionDAG-based code generation. This works around limitations in it's
11// basic-block-at-a-time approach. It should eventually be removed.
12//
13//===----------------------------------------------------------------------===//
14
15#include "llvm/ADT/APInt.h"
16#include "llvm/ADT/ArrayRef.h"
17#include "llvm/ADT/DenseMap.h"
18#include "llvm/ADT/MapVector.h"
19#include "llvm/ADT/PointerIntPair.h"
20#include "llvm/ADT/STLExtras.h"
21#include "llvm/ADT/SmallPtrSet.h"
22#include "llvm/ADT/SmallVector.h"
23#include "llvm/ADT/Statistic.h"
24#include "llvm/Analysis/BlockFrequencyInfo.h"
25#include "llvm/Analysis/BranchProbabilityInfo.h"
26#include "llvm/Analysis/ConstantFolding.h"
27#include "llvm/Analysis/InstructionSimplify.h"
28#include "llvm/Analysis/LoopInfo.h"
29#include "llvm/Analysis/MemoryBuiltins.h"
30#include "llvm/Analysis/ProfileSummaryInfo.h"
31#include "llvm/Analysis/TargetLibraryInfo.h"
32#include "llvm/Analysis/TargetTransformInfo.h"
33#include "llvm/Transforms/Utils/Local.h"
34#include "llvm/Analysis/ValueTracking.h"
35#include "llvm/Analysis/VectorUtils.h"
36#include "llvm/CodeGen/Analysis.h"
37#include "llvm/CodeGen/ISDOpcodes.h"
38#include "llvm/CodeGen/SelectionDAGNodes.h"
39#include "llvm/CodeGen/TargetLowering.h"
40#include "llvm/CodeGen/TargetPassConfig.h"
41#include "llvm/CodeGen/TargetSubtargetInfo.h"
42#include "llvm/CodeGen/ValueTypes.h"
43#include "llvm/Config/llvm-config.h"
44#include "llvm/IR/Argument.h"
45#include "llvm/IR/Attributes.h"
46#include "llvm/IR/BasicBlock.h"
47#include "llvm/IR/CallSite.h"
48#include "llvm/IR/Constant.h"
49#include "llvm/IR/Constants.h"
50#include "llvm/IR/DataLayout.h"
51#include "llvm/IR/DerivedTypes.h"
52#include "llvm/IR/Dominators.h"
53#include "llvm/IR/Function.h"
54#include "llvm/IR/GetElementPtrTypeIterator.h"
55#include "llvm/IR/GlobalValue.h"
56#include "llvm/IR/GlobalVariable.h"
57#include "llvm/IR/IRBuilder.h"
58#include "llvm/IR/InlineAsm.h"
59#include "llvm/IR/InstrTypes.h"
60#include "llvm/IR/Instruction.h"
61#include "llvm/IR/Instructions.h"
62#include "llvm/IR/IntrinsicInst.h"
63#include "llvm/IR/Intrinsics.h"
64#include "llvm/IR/LLVMContext.h"
65#include "llvm/IR/MDBuilder.h"
66#include "llvm/IR/Module.h"
67#include "llvm/IR/Operator.h"
68#include "llvm/IR/PatternMatch.h"
69#include "llvm/IR/Statepoint.h"
70#include "llvm/IR/Type.h"
71#include "llvm/IR/Use.h"
72#include "llvm/IR/User.h"
73#include "llvm/IR/Value.h"
74#include "llvm/IR/ValueHandle.h"
75#include "llvm/IR/ValueMap.h"
76#include "llvm/Pass.h"
77#include "llvm/Support/BlockFrequency.h"
78#include "llvm/Support/BranchProbability.h"
79#include "llvm/Support/Casting.h"
80#include "llvm/Support/CommandLine.h"
81#include "llvm/Support/Compiler.h"
82#include "llvm/Support/Debug.h"
83#include "llvm/Support/ErrorHandling.h"
84#include "llvm/Support/MachineValueType.h"
85#include "llvm/Support/MathExtras.h"
86#include "llvm/Support/raw_ostream.h"
87#include "llvm/Target/TargetMachine.h"
88#include "llvm/Target/TargetOptions.h"
89#include "llvm/Transforms/Utils/BasicBlockUtils.h"
90#include "llvm/Transforms/Utils/BypassSlowDivision.h"
91#include "llvm/Transforms/Utils/SimplifyLibCalls.h"
92#include <algorithm>
93#include <cassert>
94#include <cstdint>
95#include <iterator>
96#include <limits>
97#include <memory>
98#include <utility>
99#include <vector>
100
101using namespace llvm;
102using namespace llvm::PatternMatch;
103
104#define DEBUG_TYPE"codegenprepare" "codegenprepare"
105
106STATISTIC(NumBlocksElim, "Number of blocks eliminated")static llvm::Statistic NumBlocksElim = {"codegenprepare", "NumBlocksElim"
, "Number of blocks eliminated"}
;
107STATISTIC(NumPHIsElim, "Number of trivial PHIs eliminated")static llvm::Statistic NumPHIsElim = {"codegenprepare", "NumPHIsElim"
, "Number of trivial PHIs eliminated"}
;
108STATISTIC(NumGEPsElim, "Number of GEPs converted to casts")static llvm::Statistic NumGEPsElim = {"codegenprepare", "NumGEPsElim"
, "Number of GEPs converted to casts"}
;
109STATISTIC(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"
}
110 "sunken Cmps")static llvm::Statistic NumCmpUses = {"codegenprepare", "NumCmpUses"
, "Number of uses of Cmp expressions replaced with uses of " "sunken Cmps"
}
;
111STATISTIC(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"
}
112 "of sunken Casts")static llvm::Statistic NumCastUses = {"codegenprepare", "NumCastUses"
, "Number of uses of Cast expressions replaced with uses " "of sunken Casts"
}
;
113STATISTIC(NumMemoryInsts, "Number of memory instructions whose address "static llvm::Statistic NumMemoryInsts = {"codegenprepare", "NumMemoryInsts"
, "Number of memory instructions whose address " "computations were sunk"
}
114 "computations were sunk")static llvm::Statistic NumMemoryInsts = {"codegenprepare", "NumMemoryInsts"
, "Number of memory instructions whose address " "computations were sunk"
}
;
115STATISTIC(NumMemoryInstsPhiCreated,static llvm::Statistic NumMemoryInstsPhiCreated = {"codegenprepare"
, "NumMemoryInstsPhiCreated", "Number of phis created when address "
"computations were sunk to memory instructions"}
116 "Number of phis created when address "static llvm::Statistic NumMemoryInstsPhiCreated = {"codegenprepare"
, "NumMemoryInstsPhiCreated", "Number of phis created when address "
"computations were sunk to memory instructions"}
117 "computations were sunk to memory instructions")static llvm::Statistic NumMemoryInstsPhiCreated = {"codegenprepare"
, "NumMemoryInstsPhiCreated", "Number of phis created when address "
"computations were sunk to memory instructions"}
;
118STATISTIC(NumMemoryInstsSelectCreated,static llvm::Statistic NumMemoryInstsSelectCreated = {"codegenprepare"
, "NumMemoryInstsSelectCreated", "Number of select created when address "
"computations were sunk to memory instructions"}
119 "Number of select created when address "static llvm::Statistic NumMemoryInstsSelectCreated = {"codegenprepare"
, "NumMemoryInstsSelectCreated", "Number of select created when address "
"computations were sunk to memory instructions"}
120 "computations were sunk to memory instructions")static llvm::Statistic NumMemoryInstsSelectCreated = {"codegenprepare"
, "NumMemoryInstsSelectCreated", "Number of select created when address "
"computations were sunk to memory instructions"}
;
121STATISTIC(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"}
;
122STATISTIC(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"}
;
123STATISTIC(NumAndsAdded,static llvm::Statistic NumAndsAdded = {"codegenprepare", "NumAndsAdded"
, "Number of and mask instructions added to form ext loads"}
124 "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"}
;
125STATISTIC(NumAndUses, "Number of uses of and mask instructions optimized")static llvm::Statistic NumAndUses = {"codegenprepare", "NumAndUses"
, "Number of uses of and mask instructions optimized"}
;
126STATISTIC(NumRetsDup, "Number of return instructions duplicated")static llvm::Statistic NumRetsDup = {"codegenprepare", "NumRetsDup"
, "Number of return instructions duplicated"}
;
127STATISTIC(NumDbgValueMoved, "Number of debug value instructions moved")static llvm::Statistic NumDbgValueMoved = {"codegenprepare", "NumDbgValueMoved"
, "Number of debug value instructions moved"}
;
128STATISTIC(NumSelectsExpanded, "Number of selects turned into branches")static llvm::Statistic NumSelectsExpanded = {"codegenprepare"
, "NumSelectsExpanded", "Number of selects turned into branches"
}
;
129STATISTIC(NumStoreExtractExposed, "Number of store(extractelement) exposed")static llvm::Statistic NumStoreExtractExposed = {"codegenprepare"
, "NumStoreExtractExposed", "Number of store(extractelement) exposed"
}
;
130
131static cl::opt<bool> DisableBranchOpts(
132 "disable-cgp-branch-opts", cl::Hidden, cl::init(false),
133 cl::desc("Disable branch optimizations in CodeGenPrepare"));
134
135static cl::opt<bool>
136 DisableGCOpts("disable-cgp-gc-opts", cl::Hidden, cl::init(false),
137 cl::desc("Disable GC optimizations in CodeGenPrepare"));
138
139static cl::opt<bool> DisableSelectToBranch(
140 "disable-cgp-select2branch", cl::Hidden, cl::init(false),
141 cl::desc("Disable select to branch conversion."));
142
143static cl::opt<bool> AddrSinkUsingGEPs(
144 "addr-sink-using-gep", cl::Hidden, cl::init(true),
145 cl::desc("Address sinking in CGP using GEPs."));
146
147static cl::opt<bool> EnableAndCmpSinking(
148 "enable-andcmp-sinking", cl::Hidden, cl::init(true),
149 cl::desc("Enable sinkinig and/cmp into branches."));
150
151static cl::opt<bool> DisableStoreExtract(
152 "disable-cgp-store-extract", cl::Hidden, cl::init(false),
153 cl::desc("Disable store(extract) optimizations in CodeGenPrepare"));
154
155static cl::opt<bool> StressStoreExtract(
156 "stress-cgp-store-extract", cl::Hidden, cl::init(false),
157 cl::desc("Stress test store(extract) optimizations in CodeGenPrepare"));
158
159static cl::opt<bool> DisableExtLdPromotion(
160 "disable-cgp-ext-ld-promotion", cl::Hidden, cl::init(false),
161 cl::desc("Disable ext(promotable(ld)) -> promoted(ext(ld)) optimization in "
162 "CodeGenPrepare"));
163
164static cl::opt<bool> StressExtLdPromotion(
165 "stress-cgp-ext-ld-promotion", cl::Hidden, cl::init(false),
166 cl::desc("Stress test ext(promotable(ld)) -> promoted(ext(ld)) "
167 "optimization in CodeGenPrepare"));
168
169static cl::opt<bool> DisablePreheaderProtect(
170 "disable-preheader-prot", cl::Hidden, cl::init(false),
171 cl::desc("Disable protection against removing loop preheaders"));
172
173static cl::opt<bool> ProfileGuidedSectionPrefix(
174 "profile-guided-section-prefix", cl::Hidden, cl::init(true), cl::ZeroOrMore,
175 cl::desc("Use profile info to add section prefix for hot/cold functions"));
176
177static cl::opt<unsigned> FreqRatioToSkipMerge(
178 "cgp-freq-ratio-to-skip-merge", cl::Hidden, cl::init(2),
179 cl::desc("Skip merging empty blocks if (frequency of empty block) / "
180 "(frequency of destination block) is greater than this ratio"));
181
182static cl::opt<bool> ForceSplitStore(
183 "force-split-store", cl::Hidden, cl::init(false),
184 cl::desc("Force store splitting no matter what the target query says."));
185
186static cl::opt<bool>
187EnableTypePromotionMerge("cgp-type-promotion-merge", cl::Hidden,
188 cl::desc("Enable merging of redundant sexts when one is dominating"
189 " the other."), cl::init(true));
190
191static cl::opt<bool> DisableComplexAddrModes(
192 "disable-complex-addr-modes", cl::Hidden, cl::init(false),
193 cl::desc("Disables combining addressing modes with different parts "
194 "in optimizeMemoryInst."));
195
196static cl::opt<bool>
197AddrSinkNewPhis("addr-sink-new-phis", cl::Hidden, cl::init(false),
198 cl::desc("Allow creation of Phis in Address sinking."));
199
200static cl::opt<bool>
201AddrSinkNewSelects("addr-sink-new-select", cl::Hidden, cl::init(true),
202 cl::desc("Allow creation of selects in Address sinking."));
203
204static cl::opt<bool> AddrSinkCombineBaseReg(
205 "addr-sink-combine-base-reg", cl::Hidden, cl::init(true),
206 cl::desc("Allow combining of BaseReg field in Address sinking."));
207
208static cl::opt<bool> AddrSinkCombineBaseGV(
209 "addr-sink-combine-base-gv", cl::Hidden, cl::init(true),
210 cl::desc("Allow combining of BaseGV field in Address sinking."));
211
212static cl::opt<bool> AddrSinkCombineBaseOffs(
213 "addr-sink-combine-base-offs", cl::Hidden, cl::init(true),
214 cl::desc("Allow combining of BaseOffs field in Address sinking."));
215
216static cl::opt<bool> AddrSinkCombineScaledReg(
217 "addr-sink-combine-scaled-reg", cl::Hidden, cl::init(true),
218 cl::desc("Allow combining of ScaledReg field in Address sinking."));
219
220static cl::opt<bool>
221 EnableGEPOffsetSplit("cgp-split-large-offset-gep", cl::Hidden,
222 cl::init(true),
223 cl::desc("Enable splitting large offset of GEP."));
224
225static cl::opt<bool> EnableICMP_EQToICMP_ST(
226 "cgp-icmp-eq2icmp-st", cl::Hidden, cl::init(false),
227 cl::desc("Enable ICMP_EQ to ICMP_S(L|G)T conversion."));
228
229namespace {
230
231enum ExtType {
232 ZeroExtension, // Zero extension has been seen.
233 SignExtension, // Sign extension has been seen.
234 BothExtension // This extension type is used if we saw sext after
235 // ZeroExtension had been set, or if we saw zext after
236 // SignExtension had been set. It makes the type
237 // information of a promoted instruction invalid.
238};
239
240using SetOfInstrs = SmallPtrSet<Instruction *, 16>;
241using TypeIsSExt = PointerIntPair<Type *, 2, ExtType>;
242using InstrToOrigTy = DenseMap<Instruction *, TypeIsSExt>;
243using SExts = SmallVector<Instruction *, 16>;
244using ValueToSExts = DenseMap<Value *, SExts>;
245
246class TypePromotionTransaction;
247
248 class CodeGenPrepare : public FunctionPass {
249 const TargetMachine *TM = nullptr;
250 const TargetSubtargetInfo *SubtargetInfo;
251 const TargetLowering *TLI = nullptr;
252 const TargetRegisterInfo *TRI;
253 const TargetTransformInfo *TTI = nullptr;
254 const TargetLibraryInfo *TLInfo;
255 const LoopInfo *LI;
256 std::unique_ptr<BlockFrequencyInfo> BFI;
257 std::unique_ptr<BranchProbabilityInfo> BPI;
258
259 /// As we scan instructions optimizing them, this is the next instruction
260 /// to optimize. Transforms that can invalidate this should update it.
261 BasicBlock::iterator CurInstIterator;
262
263 /// Keeps track of non-local addresses that have been sunk into a block.
264 /// This allows us to avoid inserting duplicate code for blocks with
265 /// multiple load/stores of the same address. The usage of WeakTrackingVH
266 /// enables SunkAddrs to be treated as a cache whose entries can be
267 /// invalidated if a sunken address computation has been erased.
268 ValueMap<Value*, WeakTrackingVH> SunkAddrs;
269
270 /// Keeps track of all instructions inserted for the current function.
271 SetOfInstrs InsertedInsts;
272
273 /// Keeps track of the type of the related instruction before their
274 /// promotion for the current function.
275 InstrToOrigTy PromotedInsts;
276
277 /// Keep track of instructions removed during promotion.
278 SetOfInstrs RemovedInsts;
279
280 /// Keep track of sext chains based on their initial value.
281 DenseMap<Value *, Instruction *> SeenChainsForSExt;
282
283 /// Keep track of GEPs accessing the same data structures such as structs or
284 /// arrays that are candidates to be split later because of their large
285 /// size.
286 MapVector<
287 AssertingVH<Value>,
288 SmallVector<std::pair<AssertingVH<GetElementPtrInst>, int64_t>, 32>>
289 LargeOffsetGEPMap;
290
291 /// Keep track of new GEP base after splitting the GEPs having large offset.
292 SmallSet<AssertingVH<Value>, 2> NewGEPBases;
293
294 /// Map serial numbers to Large offset GEPs.
295 DenseMap<AssertingVH<GetElementPtrInst>, int> LargeOffsetGEPID;
296
297 /// Keep track of SExt promoted.
298 ValueToSExts ValToSExtendedUses;
299
300 /// True if optimizing for size.
301 bool OptSize;
302
303 /// DataLayout for the Function being processed.
304 const DataLayout *DL = nullptr;
305
306 /// Building the dominator tree can be expensive, so we only build it
307 /// lazily and update it when required.
308 std::unique_ptr<DominatorTree> DT;
309
310 public:
311 static char ID; // Pass identification, replacement for typeid
312
313 CodeGenPrepare() : FunctionPass(ID) {
314 initializeCodeGenPreparePass(*PassRegistry::getPassRegistry());
315 }
316
317 bool runOnFunction(Function &F) override;
318
319 StringRef getPassName() const override { return "CodeGen Prepare"; }
320
321 void getAnalysisUsage(AnalysisUsage &AU) const override {
322 // FIXME: When we can selectively preserve passes, preserve the domtree.
323 AU.addRequired<ProfileSummaryInfoWrapperPass>();
324 AU.addRequired<TargetLibraryInfoWrapperPass>();
325 AU.addRequired<TargetTransformInfoWrapperPass>();
326 AU.addRequired<LoopInfoWrapperPass>();
327 }
328
329 private:
330 template <typename F>
331 void resetIteratorIfInvalidatedWhileCalling(BasicBlock *BB, F f) {
332 // Substituting can cause recursive simplifications, which can invalidate
333 // our iterator. Use a WeakTrackingVH to hold onto it in case this
334 // happens.
335 Value *CurValue = &*CurInstIterator;
336 WeakTrackingVH IterHandle(CurValue);
337
338 f();
339
340 // If the iterator instruction was recursively deleted, start over at the
341 // start of the block.
342 if (IterHandle != CurValue) {
343 CurInstIterator = BB->begin();
344 SunkAddrs.clear();
345 }
346 }
347
348 // Get the DominatorTree, building if necessary.
349 DominatorTree &getDT(Function &F) {
350 if (!DT)
351 DT = std::make_unique<DominatorTree>(F);
352 return *DT;
353 }
354
355 bool eliminateFallThrough(Function &F);
356 bool eliminateMostlyEmptyBlocks(Function &F);
357 BasicBlock *findDestBlockOfMergeableEmptyBlock(BasicBlock *BB);
358 bool canMergeBlocks(const BasicBlock *BB, const BasicBlock *DestBB) const;
359 void eliminateMostlyEmptyBlock(BasicBlock *BB);
360 bool isMergingEmptyBlockProfitable(BasicBlock *BB, BasicBlock *DestBB,
361 bool isPreheader);
362 bool optimizeBlock(BasicBlock &BB, bool &ModifiedDT);
363 bool optimizeInst(Instruction *I, bool &ModifiedDT);
364 bool optimizeMemoryInst(Instruction *MemoryInst, Value *Addr,
365 Type *AccessTy, unsigned AddrSpace);
366 bool optimizeInlineAsmInst(CallInst *CS);
367 bool optimizeCallInst(CallInst *CI, bool &ModifiedDT);
368 bool optimizeExt(Instruction *&I);
369 bool optimizeExtUses(Instruction *I);
370 bool optimizeLoadExt(LoadInst *Load);
371 bool optimizeShiftInst(BinaryOperator *BO);
372 bool optimizeSelectInst(SelectInst *SI);
373 bool optimizeShuffleVectorInst(ShuffleVectorInst *SVI);
374 bool optimizeSwitchInst(SwitchInst *SI);
375 bool optimizeExtractElementInst(Instruction *Inst);
376 bool dupRetToEnableTailCallOpts(BasicBlock *BB, bool &ModifiedDT);
377 bool placeDbgValues(Function &F);
378 bool canFormExtLd(const SmallVectorImpl<Instruction *> &MovedExts,
379 LoadInst *&LI, Instruction *&Inst, bool HasPromoted);
380 bool tryToPromoteExts(TypePromotionTransaction &TPT,
381 const SmallVectorImpl<Instruction *> &Exts,
382 SmallVectorImpl<Instruction *> &ProfitablyMovedExts,
383 unsigned CreatedInstsCost = 0);
384 bool mergeSExts(Function &F);
385 bool splitLargeGEPOffsets();
386 bool performAddressTypePromotion(
387 Instruction *&Inst,
388 bool AllowPromotionWithoutCommonHeader,
389 bool HasPromoted, TypePromotionTransaction &TPT,
390 SmallVectorImpl<Instruction *> &SpeculativelyMovedExts);
391 bool splitBranchCondition(Function &F, bool &ModifiedDT);
392 bool simplifyOffsetableRelocate(Instruction &I);
393
394 bool tryToSinkFreeOperands(Instruction *I);
395 bool replaceMathCmpWithIntrinsic(BinaryOperator *BO, CmpInst *Cmp,
396 Intrinsic::ID IID);
397 bool optimizeCmp(CmpInst *Cmp, bool &ModifiedDT);
398 bool combineToUSubWithOverflow(CmpInst *Cmp, bool &ModifiedDT);
399 bool combineToUAddWithOverflow(CmpInst *Cmp, bool &ModifiedDT);
400 };
401
402} // end anonymous namespace
403
404char CodeGenPrepare::ID = 0;
405
406INITIALIZE_PASS_BEGIN(CodeGenPrepare, DEBUG_TYPE,static void *initializeCodeGenPreparePassOnce(PassRegistry &
Registry) {
407 "Optimize for code generation", false, false)static void *initializeCodeGenPreparePassOnce(PassRegistry &
Registry) {
408INITIALIZE_PASS_DEPENDENCY(ProfileSummaryInfoWrapperPass)initializeProfileSummaryInfoWrapperPassPass(Registry);
409INITIALIZE_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)); }
410 "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)); }
411
412FunctionPass *llvm::createCodeGenPreparePass() { return new CodeGenPrepare(); }
413
414bool CodeGenPrepare::runOnFunction(Function &F) {
415 if (skipFunction(F))
416 return false;
417
418 DL = &F.getParent()->getDataLayout();
419
420 bool EverMadeChange = false;
421 // Clear per function information.
422 InsertedInsts.clear();
423 PromotedInsts.clear();
424
425 if (auto *TPC = getAnalysisIfAvailable<TargetPassConfig>()) {
426 TM = &TPC->getTM<TargetMachine>();
427 SubtargetInfo = TM->getSubtargetImpl(F);
428 TLI = SubtargetInfo->getTargetLowering();
429 TRI = SubtargetInfo->getRegisterInfo();
430 }
431 TLInfo = &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(F);
432 TTI = &getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
433 LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
434 BPI.reset(new BranchProbabilityInfo(F, *LI));
435 BFI.reset(new BlockFrequencyInfo(F, *BPI, *LI));
436 OptSize = F.hasOptSize();
437
438 ProfileSummaryInfo *PSI =
439 &getAnalysis<ProfileSummaryInfoWrapperPass>().getPSI();
440 if (ProfileGuidedSectionPrefix) {
441 if (PSI->isFunctionHotInCallGraph(&F, *BFI))
442 F.setSectionPrefix(".hot");
443 else if (PSI->isFunctionColdInCallGraph(&F, *BFI))
444 F.setSectionPrefix(".unlikely");
445 }
446
447 /// This optimization identifies DIV instructions that can be
448 /// profitably bypassed and carried out with a shorter, faster divide.
449 if (!OptSize && !PSI->hasHugeWorkingSetSize() && TLI &&
450 TLI->isSlowDivBypassed()) {
451 const DenseMap<unsigned int, unsigned int> &BypassWidths =
452 TLI->getBypassSlowDivWidths();
453 BasicBlock* BB = &*F.begin();
454 while (BB != nullptr) {
455 // bypassSlowDivision may create new BBs, but we don't want to reapply the
456 // optimization to those blocks.
457 BasicBlock* Next = BB->getNextNode();
458 EverMadeChange |= bypassSlowDivision(BB, BypassWidths);
459 BB = Next;
460 }
461 }
462
463 // Eliminate blocks that contain only PHI nodes and an
464 // unconditional branch.
465 EverMadeChange |= eliminateMostlyEmptyBlocks(F);
466
467 bool ModifiedDT = false;
468 if (!DisableBranchOpts)
469 EverMadeChange |= splitBranchCondition(F, ModifiedDT);
470
471 // Split some critical edges where one of the sources is an indirect branch,
472 // to help generate sane code for PHIs involving such edges.
473 EverMadeChange |= SplitIndirectBrCriticalEdges(F);
474
475 bool MadeChange = true;
476 while (MadeChange) {
477 MadeChange = false;
478 DT.reset();
479 for (Function::iterator I = F.begin(); I != F.end(); ) {
480 BasicBlock *BB = &*I++;
481 bool ModifiedDTOnIteration = false;
482 MadeChange |= optimizeBlock(*BB, ModifiedDTOnIteration);
483
484 // Restart BB iteration if the dominator tree of the Function was changed
485 if (ModifiedDTOnIteration)
486 break;
487 }
488 if (EnableTypePromotionMerge && !ValToSExtendedUses.empty())
489 MadeChange |= mergeSExts(F);
490 if (!LargeOffsetGEPMap.empty())
491 MadeChange |= splitLargeGEPOffsets();
492
493 // Really free removed instructions during promotion.
494 for (Instruction *I : RemovedInsts)
495 I->deleteValue();
496
497 EverMadeChange |= MadeChange;
498 SeenChainsForSExt.clear();
499 ValToSExtendedUses.clear();
500 RemovedInsts.clear();
501 LargeOffsetGEPMap.clear();
502 LargeOffsetGEPID.clear();
503 }
504
505 SunkAddrs.clear();
506
507 if (!DisableBranchOpts) {
508 MadeChange = false;
509 // Use a set vector to get deterministic iteration order. The order the
510 // blocks are removed may affect whether or not PHI nodes in successors
511 // are removed.
512 SmallSetVector<BasicBlock*, 8> WorkList;
513 for (BasicBlock &BB : F) {
514 SmallVector<BasicBlock *, 2> Successors(succ_begin(&BB), succ_end(&BB));
515 MadeChange |= ConstantFoldTerminator(&BB, true);
516 if (!MadeChange) continue;
517
518 for (SmallVectorImpl<BasicBlock*>::iterator
519 II = Successors.begin(), IE = Successors.end(); II != IE; ++II)
520 if (pred_begin(*II) == pred_end(*II))
521 WorkList.insert(*II);
522 }
523
524 // Delete the dead blocks and any of their dead successors.
525 MadeChange |= !WorkList.empty();
526 while (!WorkList.empty()) {
527 BasicBlock *BB = WorkList.pop_back_val();
528 SmallVector<BasicBlock*, 2> Successors(succ_begin(BB), succ_end(BB));
529
530 DeleteDeadBlock(BB);
531
532 for (SmallVectorImpl<BasicBlock*>::iterator
533 II = Successors.begin(), IE = Successors.end(); II != IE; ++II)
534 if (pred_begin(*II) == pred_end(*II))
535 WorkList.insert(*II);
536 }
537
538 // Merge pairs of basic blocks with unconditional branches, connected by
539 // a single edge.
540 if (EverMadeChange || MadeChange)
541 MadeChange |= eliminateFallThrough(F);
542
543 EverMadeChange |= MadeChange;
544 }
545
546 if (!DisableGCOpts) {
547 SmallVector<Instruction *, 2> Statepoints;
548 for (BasicBlock &BB : F)
549 for (Instruction &I : BB)
550 if (isStatepoint(I))
551 Statepoints.push_back(&I);
552 for (auto &I : Statepoints)
553 EverMadeChange |= simplifyOffsetableRelocate(*I);
554 }
555
556 // Do this last to clean up use-before-def scenarios introduced by other
557 // preparatory transforms.
558 EverMadeChange |= placeDbgValues(F);
559
560 return EverMadeChange;
561}
562
563/// Merge basic blocks which are connected by a single edge, where one of the
564/// basic blocks has a single successor pointing to the other basic block,
565/// which has a single predecessor.
566bool CodeGenPrepare::eliminateFallThrough(Function &F) {
567 bool Changed = false;
568 // Scan all of the blocks in the function, except for the entry block.
569 // Use a temporary array to avoid iterator being invalidated when
570 // deleting blocks.
571 SmallVector<WeakTrackingVH, 16> Blocks;
572 for (auto &Block : llvm::make_range(std::next(F.begin()), F.end()))
573 Blocks.push_back(&Block);
574
575 for (auto &Block : Blocks) {
576 auto *BB = cast_or_null<BasicBlock>(Block);
577 if (!BB)
578 continue;
579 // If the destination block has a single pred, then this is a trivial
580 // edge, just collapse it.
581 BasicBlock *SinglePred = BB->getSinglePredecessor();
582
583 // Don't merge if BB's address is taken.
584 if (!SinglePred || SinglePred == BB || BB->hasAddressTaken()) continue;
585
586 BranchInst *Term = dyn_cast<BranchInst>(SinglePred->getTerminator());
587 if (Term && !Term->isConditional()) {
588 Changed = true;
589 LLVM_DEBUG(dbgs() << "To merge:\n" << *BB << "\n\n\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "To merge:\n" << *
BB << "\n\n\n"; } } while (false)
;
590
591 // Merge BB into SinglePred and delete it.
592 MergeBlockIntoPredecessor(BB);
593 }
594 }
595 return Changed;
596}
597
598/// Find a destination block from BB if BB is mergeable empty block.
599BasicBlock *CodeGenPrepare::findDestBlockOfMergeableEmptyBlock(BasicBlock *BB) {
600 // If this block doesn't end with an uncond branch, ignore it.
601 BranchInst *BI = dyn_cast<BranchInst>(BB->getTerminator());
602 if (!BI || !BI->isUnconditional())
603 return nullptr;
604
605 // If the instruction before the branch (skipping debug info) isn't a phi
606 // node, then other stuff is happening here.
607 BasicBlock::iterator BBI = BI->getIterator();
608 if (BBI != BB->begin()) {
609 --BBI;
610 while (isa<DbgInfoIntrinsic>(BBI)) {
611 if (BBI == BB->begin())
612 break;
613 --BBI;
614 }
615 if (!isa<DbgInfoIntrinsic>(BBI) && !isa<PHINode>(BBI))
616 return nullptr;
617 }
618
619 // Do not break infinite loops.
620 BasicBlock *DestBB = BI->getSuccessor(0);
621 if (DestBB == BB)
622 return nullptr;
623
624 if (!canMergeBlocks(BB, DestBB))
625 DestBB = nullptr;
626
627 return DestBB;
628}
629
630/// Eliminate blocks that contain only PHI nodes, debug info directives, and an
631/// unconditional branch. Passes before isel (e.g. LSR/loopsimplify) often split
632/// edges in ways that are non-optimal for isel. Start by eliminating these
633/// blocks so we can split them the way we want them.
634bool CodeGenPrepare::eliminateMostlyEmptyBlocks(Function &F) {
635 SmallPtrSet<BasicBlock *, 16> Preheaders;
636 SmallVector<Loop *, 16> LoopList(LI->begin(), LI->end());
637 while (!LoopList.empty()) {
638 Loop *L = LoopList.pop_back_val();
639 LoopList.insert(LoopList.end(), L->begin(), L->end());
640 if (BasicBlock *Preheader = L->getLoopPreheader())
641 Preheaders.insert(Preheader);
642 }
643
644 bool MadeChange = false;
645 // Copy blocks into a temporary array to avoid iterator invalidation issues
646 // as we remove them.
647 // Note that this intentionally skips the entry block.
648 SmallVector<WeakTrackingVH, 16> Blocks;
649 for (auto &Block : llvm::make_range(std::next(F.begin()), F.end()))
650 Blocks.push_back(&Block);
651
652 for (auto &Block : Blocks) {
653 BasicBlock *BB = cast_or_null<BasicBlock>(Block);
654 if (!BB)
655 continue;
656 BasicBlock *DestBB = findDestBlockOfMergeableEmptyBlock(BB);
657 if (!DestBB ||
658 !isMergingEmptyBlockProfitable(BB, DestBB, Preheaders.count(BB)))
659 continue;
660
661 eliminateMostlyEmptyBlock(BB);
662 MadeChange = true;
663 }
664 return MadeChange;
665}
666
667bool CodeGenPrepare::isMergingEmptyBlockProfitable(BasicBlock *BB,
668 BasicBlock *DestBB,
669 bool isPreheader) {
670 // Do not delete loop preheaders if doing so would create a critical edge.
671 // Loop preheaders can be good locations to spill registers. If the
672 // preheader is deleted and we create a critical edge, registers may be
673 // spilled in the loop body instead.
674 if (!DisablePreheaderProtect && isPreheader &&
675 !(BB->getSinglePredecessor() &&
676 BB->getSinglePredecessor()->getSingleSuccessor()))
677 return false;
678
679 // Skip merging if the block's successor is also a successor to any callbr
680 // that leads to this block.
681 // FIXME: Is this really needed? Is this a correctness issue?
682 for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) {
683 if (auto *CBI = dyn_cast<CallBrInst>((*PI)->getTerminator()))
684 for (unsigned i = 0, e = CBI->getNumSuccessors(); i != e; ++i)
685 if (DestBB == CBI->getSuccessor(i))
686 return false;
687 }
688
689 // Try to skip merging if the unique predecessor of BB is terminated by a
690 // switch or indirect branch instruction, and BB is used as an incoming block
691 // of PHIs in DestBB. In such case, merging BB and DestBB would cause ISel to
692 // add COPY instructions in the predecessor of BB instead of BB (if it is not
693 // merged). Note that the critical edge created by merging such blocks wont be
694 // split in MachineSink because the jump table is not analyzable. By keeping
695 // such empty block (BB), ISel will place COPY instructions in BB, not in the
696 // predecessor of BB.
697 BasicBlock *Pred = BB->getUniquePredecessor();
698 if (!Pred ||
699 !(isa<SwitchInst>(Pred->getTerminator()) ||
700 isa<IndirectBrInst>(Pred->getTerminator())))
701 return true;
702
703 if (BB->getTerminator() != BB->getFirstNonPHIOrDbg())
704 return true;
705
706 // We use a simple cost heuristic which determine skipping merging is
707 // profitable if the cost of skipping merging is less than the cost of
708 // merging : Cost(skipping merging) < Cost(merging BB), where the
709 // Cost(skipping merging) is Freq(BB) * (Cost(Copy) + Cost(Branch)), and
710 // the Cost(merging BB) is Freq(Pred) * Cost(Copy).
711 // Assuming Cost(Copy) == Cost(Branch), we could simplify it to :
712 // Freq(Pred) / Freq(BB) > 2.
713 // Note that if there are multiple empty blocks sharing the same incoming
714 // value for the PHIs in the DestBB, we consider them together. In such
715 // case, Cost(merging BB) will be the sum of their frequencies.
716
717 if (!isa<PHINode>(DestBB->begin()))
718 return true;
719
720 SmallPtrSet<BasicBlock *, 16> SameIncomingValueBBs;
721
722 // Find all other incoming blocks from which incoming values of all PHIs in
723 // DestBB are the same as the ones from BB.
724 for (pred_iterator PI = pred_begin(DestBB), E = pred_end(DestBB); PI != E;
725 ++PI) {
726 BasicBlock *DestBBPred = *PI;
727 if (DestBBPred == BB)
728 continue;
729
730 if (llvm::all_of(DestBB->phis(), [&](const PHINode &DestPN) {
731 return DestPN.getIncomingValueForBlock(BB) ==
732 DestPN.getIncomingValueForBlock(DestBBPred);
733 }))
734 SameIncomingValueBBs.insert(DestBBPred);
735 }
736
737 // See if all BB's incoming values are same as the value from Pred. In this
738 // case, no reason to skip merging because COPYs are expected to be place in
739 // Pred already.
740 if (SameIncomingValueBBs.count(Pred))
741 return true;
742
743 BlockFrequency PredFreq = BFI->getBlockFreq(Pred);
744 BlockFrequency BBFreq = BFI->getBlockFreq(BB);
745
746 for (auto SameValueBB : SameIncomingValueBBs)
747 if (SameValueBB->getUniquePredecessor() == Pred &&
748 DestBB == findDestBlockOfMergeableEmptyBlock(SameValueBB))
749 BBFreq += BFI->getBlockFreq(SameValueBB);
750
751 return PredFreq.getFrequency() <=
752 BBFreq.getFrequency() * FreqRatioToSkipMerge;
753}
754
755/// Return true if we can merge BB into DestBB if there is a single
756/// unconditional branch between them, and BB contains no other non-phi
757/// instructions.
758bool CodeGenPrepare::canMergeBlocks(const BasicBlock *BB,
759 const BasicBlock *DestBB) const {
760 // We only want to eliminate blocks whose phi nodes are used by phi nodes in
761 // the successor. If there are more complex condition (e.g. preheaders),
762 // don't mess around with them.
763 for (const PHINode &PN : BB->phis()) {
764 for (const User *U : PN.users()) {
765 const Instruction *UI = cast<Instruction>(U);
766 if (UI->getParent() != DestBB || !isa<PHINode>(UI))
767 return false;
768 // If User is inside DestBB block and it is a PHINode then check
769 // incoming value. If incoming value is not from BB then this is
770 // a complex condition (e.g. preheaders) we want to avoid here.
771 if (UI->getParent() == DestBB) {
772 if (const PHINode *UPN = dyn_cast<PHINode>(UI))
773 for (unsigned I = 0, E = UPN->getNumIncomingValues(); I != E; ++I) {
774 Instruction *Insn = dyn_cast<Instruction>(UPN->getIncomingValue(I));
775 if (Insn && Insn->getParent() == BB &&
776 Insn->getParent() != UPN->getIncomingBlock(I))
777 return false;
778 }
779 }
780 }
781 }
782
783 // If BB and DestBB contain any common predecessors, then the phi nodes in BB
784 // and DestBB may have conflicting incoming values for the block. If so, we
785 // can't merge the block.
786 const PHINode *DestBBPN = dyn_cast<PHINode>(DestBB->begin());
787 if (!DestBBPN) return true; // no conflict.
788
789 // Collect the preds of BB.
790 SmallPtrSet<const BasicBlock*, 16> BBPreds;
791 if (const PHINode *BBPN = dyn_cast<PHINode>(BB->begin())) {
792 // It is faster to get preds from a PHI than with pred_iterator.
793 for (unsigned i = 0, e = BBPN->getNumIncomingValues(); i != e; ++i)
794 BBPreds.insert(BBPN->getIncomingBlock(i));
795 } else {
796 BBPreds.insert(pred_begin(BB), pred_end(BB));
797 }
798
799 // Walk the preds of DestBB.
800 for (unsigned i = 0, e = DestBBPN->getNumIncomingValues(); i != e; ++i) {
801 BasicBlock *Pred = DestBBPN->getIncomingBlock(i);
802 if (BBPreds.count(Pred)) { // Common predecessor?
803 for (const PHINode &PN : DestBB->phis()) {
804 const Value *V1 = PN.getIncomingValueForBlock(Pred);
805 const Value *V2 = PN.getIncomingValueForBlock(BB);
806
807 // If V2 is a phi node in BB, look up what the mapped value will be.
808 if (const PHINode *V2PN = dyn_cast<PHINode>(V2))
809 if (V2PN->getParent() == BB)
810 V2 = V2PN->getIncomingValueForBlock(Pred);
811
812 // If there is a conflict, bail out.
813 if (V1 != V2) return false;
814 }
815 }
816 }
817
818 return true;
819}
820
821/// Eliminate a basic block that has only phi's and an unconditional branch in
822/// it.
823void CodeGenPrepare::eliminateMostlyEmptyBlock(BasicBlock *BB) {
824 BranchInst *BI = cast<BranchInst>(BB->getTerminator());
825 BasicBlock *DestBB = BI->getSuccessor(0);
826
827 LLVM_DEBUG(dbgs() << "MERGING MOSTLY EMPTY BLOCKS - BEFORE:\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "MERGING MOSTLY EMPTY BLOCKS - BEFORE:\n"
<< *BB << *DestBB; } } while (false)
828 << *BB << *DestBB)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "MERGING MOSTLY EMPTY BLOCKS - BEFORE:\n"
<< *BB << *DestBB; } } while (false)
;
829
830 // If the destination block has a single pred, then this is a trivial edge,
831 // just collapse it.
832 if (BasicBlock *SinglePred = DestBB->getSinglePredecessor()) {
833 if (SinglePred != DestBB) {
834 assert(SinglePred == BB &&((SinglePred == BB && "Single predecessor not the same as predecessor"
) ? static_cast<void> (0) : __assert_fail ("SinglePred == BB && \"Single predecessor not the same as predecessor\""
, "/build/llvm-toolchain-snapshot-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 835, __PRETTY_FUNCTION__))
835 "Single predecessor not the same as predecessor")((SinglePred == BB && "Single predecessor not the same as predecessor"
) ? static_cast<void> (0) : __assert_fail ("SinglePred == BB && \"Single predecessor not the same as predecessor\""
, "/build/llvm-toolchain-snapshot-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 835, __PRETTY_FUNCTION__))
;
836 // Merge DestBB into SinglePred/BB and delete it.
837 MergeBlockIntoPredecessor(DestBB);
838 // Note: BB(=SinglePred) will not be deleted on this path.
839 // DestBB(=its single successor) is the one that was deleted.
840 LLVM_DEBUG(dbgs() << "AFTER:\n" << *SinglePred << "\n\n\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "AFTER:\n" << *SinglePred
<< "\n\n\n"; } } while (false)
;
841 return;
842 }
843 }
844
845 // Otherwise, we have multiple predecessors of BB. Update the PHIs in DestBB
846 // to handle the new incoming edges it is about to have.
847 for (PHINode &PN : DestBB->phis()) {
848 // Remove the incoming value for BB, and remember it.
849 Value *InVal = PN.removeIncomingValue(BB, false);
850
851 // Two options: either the InVal is a phi node defined in BB or it is some
852 // value that dominates BB.
853 PHINode *InValPhi = dyn_cast<PHINode>(InVal);
854 if (InValPhi && InValPhi->getParent() == BB) {
855 // Add all of the input values of the input PHI as inputs of this phi.
856 for (unsigned i = 0, e = InValPhi->getNumIncomingValues(); i != e; ++i)
857 PN.addIncoming(InValPhi->getIncomingValue(i),
858 InValPhi->getIncomingBlock(i));
859 } else {
860 // Otherwise, add one instance of the dominating value for each edge that
861 // we will be adding.
862 if (PHINode *BBPN = dyn_cast<PHINode>(BB->begin())) {
863 for (unsigned i = 0, e = BBPN->getNumIncomingValues(); i != e; ++i)
864 PN.addIncoming(InVal, BBPN->getIncomingBlock(i));
865 } else {
866 for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI)
867 PN.addIncoming(InVal, *PI);
868 }
869 }
870 }
871
872 // The PHIs are now updated, change everything that refers to BB to use
873 // DestBB and remove BB.
874 BB->replaceAllUsesWith(DestBB);
875 BB->eraseFromParent();
876 ++NumBlocksElim;
877
878 LLVM_DEBUG(dbgs() << "AFTER:\n" << *DestBB << "\n\n\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "AFTER:\n" << *DestBB
<< "\n\n\n"; } } while (false)
;
879}
880
881// Computes a map of base pointer relocation instructions to corresponding
882// derived pointer relocation instructions given a vector of all relocate calls
883static void computeBaseDerivedRelocateMap(
884 const SmallVectorImpl<GCRelocateInst *> &AllRelocateCalls,
885 DenseMap<GCRelocateInst *, SmallVector<GCRelocateInst *, 2>>
886 &RelocateInstMap) {
887 // Collect information in two maps: one primarily for locating the base object
888 // while filling the second map; the second map is the final structure holding
889 // a mapping between Base and corresponding Derived relocate calls
890 DenseMap<std::pair<unsigned, unsigned>, GCRelocateInst *> RelocateIdxMap;
891 for (auto *ThisRelocate : AllRelocateCalls) {
892 auto K = std::make_pair(ThisRelocate->getBasePtrIndex(),
893 ThisRelocate->getDerivedPtrIndex());
894 RelocateIdxMap.insert(std::make_pair(K, ThisRelocate));
895 }
896 for (auto &Item : RelocateIdxMap) {
897 std::pair<unsigned, unsigned> Key = Item.first;
898 if (Key.first == Key.second)
899 // Base relocation: nothing to insert
900 continue;
901
902 GCRelocateInst *I = Item.second;
903 auto BaseKey = std::make_pair(Key.first, Key.first);
904
905 // We're iterating over RelocateIdxMap so we cannot modify it.
906 auto MaybeBase = RelocateIdxMap.find(BaseKey);
907 if (MaybeBase == RelocateIdxMap.end())
908 // TODO: We might want to insert a new base object relocate and gep off
909 // that, if there are enough derived object relocates.
910 continue;
911
912 RelocateInstMap[MaybeBase->second].push_back(I);
913 }
914}
915
916// Accepts a GEP and extracts the operands into a vector provided they're all
917// small integer constants
918static bool getGEPSmallConstantIntOffsetV(GetElementPtrInst *GEP,
919 SmallVectorImpl<Value *> &OffsetV) {
920 for (unsigned i = 1; i < GEP->getNumOperands(); i++) {
20
Assuming the condition is false
21
Loop condition is false. Execution continues on line 927
921 // Only accept small constant integer operands
922 auto Op = dyn_cast<ConstantInt>(GEP->getOperand(i));
923 if (!Op || Op->getZExtValue() > 20)
924 return false;
925 }
926
927 for (unsigned i = 1; i < GEP->getNumOperands(); i++)
22
Loop condition is false. Execution continues on line 929
928 OffsetV.push_back(GEP->getOperand(i));
929 return true;
23
Returning the value 1, which participates in a condition later
930}
931
932// Takes a RelocatedBase (base pointer relocation instruction) and Targets to
933// replace, computes a replacement, and affects it.
934static bool
935simplifyRelocatesOffABase(GCRelocateInst *RelocatedBase,
936 const SmallVectorImpl<GCRelocateInst *> &Targets) {
937 bool MadeChange = false;
938 // We must ensure the relocation of derived pointer is defined after
939 // relocation of base pointer. If we find a relocation corresponding to base
940 // defined earlier than relocation of base then we move relocation of base
941 // right before found relocation. We consider only relocation in the same
942 // basic block as relocation of base. Relocations from other basic block will
943 // be skipped by optimization and we do not care about them.
944 for (auto R = RelocatedBase->getParent()->getFirstInsertionPt();
7
Loop condition is false. Execution continues on line 953
945 &*R != RelocatedBase; ++R)
6
Assuming the condition is false
946 if (auto RI = dyn_cast<GCRelocateInst>(R))
947 if (RI->getStatepoint() == RelocatedBase->getStatepoint())
948 if (RI->getBasePtrIndex() == RelocatedBase->getBasePtrIndex()) {
949 RelocatedBase->moveBefore(RI);
950 break;
951 }
952
953 for (GCRelocateInst *ToReplace : Targets) {
8
Assuming '__begin1' is not equal to '__end1'
954 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-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 955, __PRETTY_FUNCTION__))
9
Assuming the condition is true
10
'?' condition is true
955 "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-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 955, __PRETTY_FUNCTION__))
;
956 if (ToReplace->getBasePtrIndex() == ToReplace->getDerivedPtrIndex()) {
11
Assuming the condition is false
12
Taking false branch
957 // A duplicate relocate call. TODO: coalesce duplicates.
958 continue;
959 }
960
961 if (RelocatedBase->getParent() != ToReplace->getParent()) {
13
Assuming the condition is false
14
Taking false branch
962 // Base and derived relocates are in different basic blocks.
963 // In this case transform is only valid when base dominates derived
964 // relocate. However it would be too expensive to check dominance
965 // for each such relocate, so we skip the whole transformation.
966 continue;
967 }
968
969 Value *Base = ToReplace->getBasePtr();
15
'Base' initialized here
970 auto Derived = dyn_cast<GetElementPtrInst>(ToReplace->getDerivedPtr());
16
Assuming the object is a 'GetElementPtrInst'
971 if (!Derived
16.1
'Derived' is non-null
|| Derived->getPointerOperand() != Base)
17
Assuming pointer value is null
18
Taking false branch
972 continue;
973
974 SmallVector<Value *, 2> OffsetV;
975 if (!getGEPSmallConstantIntOffsetV(Derived, OffsetV))
19
Calling 'getGEPSmallConstantIntOffsetV'
24
Returning from 'getGEPSmallConstantIntOffsetV'
25
Taking false branch
976 continue;
977
978 // Create a Builder and replace the target callsite with a gep
979 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-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 980, __PRETTY_FUNCTION__))
26
Assuming the condition is true
27
'?' condition is true
980 "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-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 980, __PRETTY_FUNCTION__))
;
981
982 // Insert after RelocatedBase
983 IRBuilder<> Builder(RelocatedBase->getNextNode());
984 Builder.SetCurrentDebugLocation(ToReplace->getDebugLoc());
985
986 // If gc_relocate does not match the actual type, cast it to the right type.
987 // In theory, there must be a bitcast after gc_relocate if the type does not
988 // match, and we should reuse it to get the derived pointer. But it could be
989 // cases like this:
990 // bb1:
991 // ...
992 // %g1 = call coldcc i8 addrspace(1)* @llvm.experimental.gc.relocate.p1i8(...)
993 // br label %merge
994 //
995 // bb2:
996 // ...
997 // %g2 = call coldcc i8 addrspace(1)* @llvm.experimental.gc.relocate.p1i8(...)
998 // br label %merge
999 //
1000 // merge:
1001 // %p1 = phi i8 addrspace(1)* [ %g1, %bb1 ], [ %g2, %bb2 ]
1002 // %cast = bitcast i8 addrspace(1)* %p1 in to i32 addrspace(1)*
1003 //
1004 // In this case, we can not find the bitcast any more. So we insert a new bitcast
1005 // no matter there is already one or not. In this way, we can handle all cases, and
1006 // the extra bitcast should be optimized away in later passes.
1007 Value *ActualRelocatedBase = RelocatedBase;
1008 if (RelocatedBase->getType() != Base->getType()) {
28
Called C++ object pointer is null
1009 ActualRelocatedBase =
1010 Builder.CreateBitCast(RelocatedBase, Base->getType());
1011 }
1012 Value *Replacement = Builder.CreateGEP(
1013 Derived->getSourceElementType(), ActualRelocatedBase, makeArrayRef(OffsetV));
1014 Replacement->takeName(ToReplace);
1015 // If the newly generated derived pointer's type does not match the original derived
1016 // pointer's type, cast the new derived pointer to match it. Same reasoning as above.
1017 Value *ActualReplacement = Replacement;
1018 if (Replacement->getType() != ToReplace->getType()) {
1019 ActualReplacement =
1020 Builder.CreateBitCast(Replacement, ToReplace->getType());
1021 }
1022 ToReplace->replaceAllUsesWith(ActualReplacement);
1023 ToReplace->eraseFromParent();
1024
1025 MadeChange = true;
1026 }
1027 return MadeChange;
1028}
1029
1030// Turns this:
1031//
1032// %base = ...
1033// %ptr = gep %base + 15
1034// %tok = statepoint (%fun, i32 0, i32 0, i32 0, %base, %ptr)
1035// %base' = relocate(%tok, i32 4, i32 4)
1036// %ptr' = relocate(%tok, i32 4, i32 5)
1037// %val = load %ptr'
1038//
1039// into this:
1040//
1041// %base = ...
1042// %ptr = gep %base + 15
1043// %tok = statepoint (%fun, i32 0, i32 0, i32 0, %base, %ptr)
1044// %base' = gc.relocate(%tok, i32 4, i32 4)
1045// %ptr' = gep %base' + 15
1046// %val = load %ptr'
1047bool CodeGenPrepare::simplifyOffsetableRelocate(Instruction &I) {
1048 bool MadeChange = false;
1049 SmallVector<GCRelocateInst *, 2> AllRelocateCalls;
1050
1051 for (auto *U : I.users())
1052 if (GCRelocateInst *Relocate = dyn_cast<GCRelocateInst>(U))
1053 // Collect all the relocate calls associated with a statepoint
1054 AllRelocateCalls.push_back(Relocate);
1055
1056 // We need atleast one base pointer relocation + one derived pointer
1057 // relocation to mangle
1058 if (AllRelocateCalls.size() < 2)
1
Assuming the condition is false
2
Taking false branch
1059 return false;
1060
1061 // RelocateInstMap is a mapping from the base relocate instruction to the
1062 // corresponding derived relocate instructions
1063 DenseMap<GCRelocateInst *, SmallVector<GCRelocateInst *, 2>> RelocateInstMap;
1064 computeBaseDerivedRelocateMap(AllRelocateCalls, RelocateInstMap);
1065 if (RelocateInstMap.empty())
3
Assuming the condition is false
4
Taking false branch
1066 return false;
1067
1068 for (auto &Item : RelocateInstMap)
1069 // Item.first is the RelocatedBase to offset against
1070 // Item.second is the vector of Targets to replace
1071 MadeChange = simplifyRelocatesOffABase(Item.first, Item.second);
5
Calling 'simplifyRelocatesOffABase'
1072 return MadeChange;
1073}
1074
1075/// Sink the specified cast instruction into its user blocks.
1076static bool SinkCast(CastInst *CI) {
1077 BasicBlock *DefBB = CI->getParent();
1078
1079 /// InsertedCasts - Only insert a cast in each block once.
1080 DenseMap<BasicBlock*, CastInst*> InsertedCasts;
1081
1082 bool MadeChange = false;
1083 for (Value::user_iterator UI = CI->user_begin(), E = CI->user_end();
1084 UI != E; ) {
1085 Use &TheUse = UI.getUse();
1086 Instruction *User = cast<Instruction>(*UI);
1087
1088 // Figure out which BB this cast is used in. For PHI's this is the
1089 // appropriate predecessor block.
1090 BasicBlock *UserBB = User->getParent();
1091 if (PHINode *PN = dyn_cast<PHINode>(User)) {
1092 UserBB = PN->getIncomingBlock(TheUse);
1093 }
1094
1095 // Preincrement use iterator so we don't invalidate it.
1096 ++UI;
1097
1098 // The first insertion point of a block containing an EH pad is after the
1099 // pad. If the pad is the user, we cannot sink the cast past the pad.
1100 if (User->isEHPad())
1101 continue;
1102
1103 // If the block selected to receive the cast is an EH pad that does not
1104 // allow non-PHI instructions before the terminator, we can't sink the
1105 // cast.
1106 if (UserBB->getTerminator()->isEHPad())
1107 continue;
1108
1109 // If this user is in the same block as the cast, don't change the cast.
1110 if (UserBB == DefBB) continue;
1111
1112 // If we have already inserted a cast into this block, use it.
1113 CastInst *&InsertedCast = InsertedCasts[UserBB];
1114
1115 if (!InsertedCast) {
1116 BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
1117 assert(InsertPt != UserBB->end())((InsertPt != UserBB->end()) ? static_cast<void> (0)
: __assert_fail ("InsertPt != UserBB->end()", "/build/llvm-toolchain-snapshot-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 1117, __PRETTY_FUNCTION__))
;
1118 InsertedCast = CastInst::Create(CI->getOpcode(), CI->getOperand(0),
1119 CI->getType(), "", &*InsertPt);
1120 InsertedCast->setDebugLoc(CI->getDebugLoc());
1121 }
1122
1123 // Replace a use of the cast with a use of the new cast.
1124 TheUse = InsertedCast;
1125 MadeChange = true;
1126 ++NumCastUses;
1127 }
1128
1129 // If we removed all uses, nuke the cast.
1130 if (CI->use_empty()) {
1131 salvageDebugInfo(*CI);
1132 CI->eraseFromParent();
1133 MadeChange = true;
1134 }
1135
1136 return MadeChange;
1137}
1138
1139/// If the specified cast instruction is a noop copy (e.g. it's casting from
1140/// one pointer type to another, i32->i8 on PPC), sink it into user blocks to
1141/// reduce the number of virtual registers that must be created and coalesced.
1142///
1143/// Return true if any changes are made.
1144static bool OptimizeNoopCopyExpression(CastInst *CI, const TargetLowering &TLI,
1145 const DataLayout &DL) {
1146 // Sink only "cheap" (or nop) address-space casts. This is a weaker condition
1147 // than sinking only nop casts, but is helpful on some platforms.
1148 if (auto *ASC = dyn_cast<AddrSpaceCastInst>(CI)) {
1149 if (!TLI.isFreeAddrSpaceCast(ASC->getSrcAddressSpace(),
1150 ASC->getDestAddressSpace()))
1151 return false;
1152 }
1153
1154 // If this is a noop copy,
1155 EVT SrcVT = TLI.getValueType(DL, CI->getOperand(0)->getType());
1156 EVT DstVT = TLI.getValueType(DL, CI->getType());
1157
1158 // This is an fp<->int conversion?
1159 if (SrcVT.isInteger() != DstVT.isInteger())
1160 return false;
1161
1162 // If this is an extension, it will be a zero or sign extension, which
1163 // isn't a noop.
1164 if (SrcVT.bitsLT(DstVT)) return false;
1165
1166 // If these values will be promoted, find out what they will be promoted
1167 // to. This helps us consider truncates on PPC as noop copies when they
1168 // are.
1169 if (TLI.getTypeAction(CI->getContext(), SrcVT) ==
1170 TargetLowering::TypePromoteInteger)
1171 SrcVT = TLI.getTypeToTransformTo(CI->getContext(), SrcVT);
1172 if (TLI.getTypeAction(CI->getContext(), DstVT) ==
1173 TargetLowering::TypePromoteInteger)
1174 DstVT = TLI.getTypeToTransformTo(CI->getContext(), DstVT);
1175
1176 // If, after promotion, these are the same types, this is a noop copy.
1177 if (SrcVT != DstVT)
1178 return false;
1179
1180 return SinkCast(CI);
1181}
1182
1183bool CodeGenPrepare::replaceMathCmpWithIntrinsic(BinaryOperator *BO,
1184 CmpInst *Cmp,
1185 Intrinsic::ID IID) {
1186 if (BO->getParent() != Cmp->getParent()) {
1187 // We used to use a dominator tree here to allow multi-block optimization.
1188 // But that was problematic because:
1189 // 1. It could cause a perf regression by hoisting the math op into the
1190 // critical path.
1191 // 2. It could cause a perf regression by creating a value that was live
1192 // across multiple blocks and increasing register pressure.
1193 // 3. Use of a dominator tree could cause large compile-time regression.
1194 // This is because we recompute the DT on every change in the main CGP
1195 // run-loop. The recomputing is probably unnecessary in many cases, so if
1196 // that was fixed, using a DT here would be ok.
1197 return false;
1198 }
1199
1200 // We allow matching the canonical IR (add X, C) back to (usubo X, -C).
1201 Value *Arg0 = BO->getOperand(0);
1202 Value *Arg1 = BO->getOperand(1);
1203 if (BO->getOpcode() == Instruction::Add &&
1204 IID == Intrinsic::usub_with_overflow) {
1205 assert(isa<Constant>(Arg1) && "Unexpected input for usubo")((isa<Constant>(Arg1) && "Unexpected input for usubo"
) ? static_cast<void> (0) : __assert_fail ("isa<Constant>(Arg1) && \"Unexpected input for usubo\""
, "/build/llvm-toolchain-snapshot-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 1205, __PRETTY_FUNCTION__))
;
1206 Arg1 = ConstantExpr::getNeg(cast<Constant>(Arg1));
1207 }
1208
1209 // Insert at the first instruction of the pair.
1210 Instruction *InsertPt = nullptr;
1211 for (Instruction &Iter : *Cmp->getParent()) {
1212 if (&Iter == BO || &Iter == Cmp) {
1213 InsertPt = &Iter;
1214 break;
1215 }
1216 }
1217 assert(InsertPt != nullptr && "Parent block did not contain cmp or binop")((InsertPt != nullptr && "Parent block did not contain cmp or binop"
) ? static_cast<void> (0) : __assert_fail ("InsertPt != nullptr && \"Parent block did not contain cmp or binop\""
, "/build/llvm-toolchain-snapshot-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 1217, __PRETTY_FUNCTION__))
;
1218
1219 IRBuilder<> Builder(InsertPt);
1220 Value *MathOV = Builder.CreateBinaryIntrinsic(IID, Arg0, Arg1);
1221 Value *Math = Builder.CreateExtractValue(MathOV, 0, "math");
1222 Value *OV = Builder.CreateExtractValue(MathOV, 1, "ov");
1223 BO->replaceAllUsesWith(Math);
1224 Cmp->replaceAllUsesWith(OV);
1225 BO->eraseFromParent();
1226 Cmp->eraseFromParent();
1227 return true;
1228}
1229
1230/// Match special-case patterns that check for unsigned add overflow.
1231static bool matchUAddWithOverflowConstantEdgeCases(CmpInst *Cmp,
1232 BinaryOperator *&Add) {
1233 // Add = add A, 1; Cmp = icmp eq A,-1 (overflow if A is max val)
1234 // Add = add A,-1; Cmp = icmp ne A, 0 (overflow if A is non-zero)
1235 Value *A = Cmp->getOperand(0), *B = Cmp->getOperand(1);
1236
1237 // We are not expecting non-canonical/degenerate code. Just bail out.
1238 if (isa<Constant>(A))
1239 return false;
1240
1241 ICmpInst::Predicate Pred = Cmp->getPredicate();
1242 if (Pred == ICmpInst::ICMP_EQ && match(B, m_AllOnes()))
1243 B = ConstantInt::get(B->getType(), 1);
1244 else if (Pred == ICmpInst::ICMP_NE && match(B, m_ZeroInt()))
1245 B = ConstantInt::get(B->getType(), -1);
1246 else
1247 return false;
1248
1249 // Check the users of the variable operand of the compare looking for an add
1250 // with the adjusted constant.
1251 for (User *U : A->users()) {
1252 if (match(U, m_Add(m_Specific(A), m_Specific(B)))) {
1253 Add = cast<BinaryOperator>(U);
1254 return true;
1255 }
1256 }
1257 return false;
1258}
1259
1260/// Try to combine the compare into a call to the llvm.uadd.with.overflow
1261/// intrinsic. Return true if any changes were made.
1262bool CodeGenPrepare::combineToUAddWithOverflow(CmpInst *Cmp,
1263 bool &ModifiedDT) {
1264 Value *A, *B;
1265 BinaryOperator *Add;
1266 if (!match(Cmp, m_UAddWithOverflow(m_Value(A), m_Value(B), m_BinOp(Add))))
1267 if (!matchUAddWithOverflowConstantEdgeCases(Cmp, Add))
1268 return false;
1269
1270 if (!TLI->shouldFormOverflowOp(ISD::UADDO,
1271 TLI->getValueType(*DL, Add->getType())))
1272 return false;
1273
1274 // We don't want to move around uses of condition values this late, so we
1275 // check if it is legal to create the call to the intrinsic in the basic
1276 // block containing the icmp.
1277 if (Add->getParent() != Cmp->getParent() && !Add->hasOneUse())
1278 return false;
1279
1280 if (!replaceMathCmpWithIntrinsic(Add, Cmp, Intrinsic::uadd_with_overflow))
1281 return false;
1282
1283 // Reset callers - do not crash by iterating over a dead instruction.
1284 ModifiedDT = true;
1285 return true;
1286}
1287
1288bool CodeGenPrepare::combineToUSubWithOverflow(CmpInst *Cmp,
1289 bool &ModifiedDT) {
1290 // We are not expecting non-canonical/degenerate code. Just bail out.
1291 Value *A = Cmp->getOperand(0), *B = Cmp->getOperand(1);
1292 if (isa<Constant>(A) && isa<Constant>(B))
1293 return false;
1294
1295 // Convert (A u> B) to (A u< B) to simplify pattern matching.
1296 ICmpInst::Predicate Pred = Cmp->getPredicate();
1297 if (Pred == ICmpInst::ICMP_UGT) {
1298 std::swap(A, B);
1299 Pred = ICmpInst::ICMP_ULT;
1300 }
1301 // Convert special-case: (A == 0) is the same as (A u< 1).
1302 if (Pred == ICmpInst::ICMP_EQ && match(B, m_ZeroInt())) {
1303 B = ConstantInt::get(B->getType(), 1);
1304 Pred = ICmpInst::ICMP_ULT;
1305 }
1306 // Convert special-case: (A != 0) is the same as (0 u< A).
1307 if (Pred == ICmpInst::ICMP_NE && match(B, m_ZeroInt())) {
1308 std::swap(A, B);
1309 Pred = ICmpInst::ICMP_ULT;
1310 }
1311 if (Pred != ICmpInst::ICMP_ULT)
1312 return false;
1313
1314 // Walk the users of a variable operand of a compare looking for a subtract or
1315 // add with that same operand. Also match the 2nd operand of the compare to
1316 // the add/sub, but that may be a negated constant operand of an add.
1317 Value *CmpVariableOperand = isa<Constant>(A) ? B : A;
1318 BinaryOperator *Sub = nullptr;
1319 for (User *U : CmpVariableOperand->users()) {
1320 // A - B, A u< B --> usubo(A, B)
1321 if (match(U, m_Sub(m_Specific(A), m_Specific(B)))) {
1322 Sub = cast<BinaryOperator>(U);
1323 break;
1324 }
1325
1326 // A + (-C), A u< C (canonicalized form of (sub A, C))
1327 const APInt *CmpC, *AddC;
1328 if (match(U, m_Add(m_Specific(A), m_APInt(AddC))) &&
1329 match(B, m_APInt(CmpC)) && *AddC == -(*CmpC)) {
1330 Sub = cast<BinaryOperator>(U);
1331 break;
1332 }
1333 }
1334 if (!Sub)
1335 return false;
1336
1337 if (!TLI->shouldFormOverflowOp(ISD::USUBO,
1338 TLI->getValueType(*DL, Sub->getType())))
1339 return false;
1340
1341 if (!replaceMathCmpWithIntrinsic(Sub, Cmp, Intrinsic::usub_with_overflow))
1342 return false;
1343
1344 // Reset callers - do not crash by iterating over a dead instruction.
1345 ModifiedDT = true;
1346 return true;
1347}
1348
1349/// Sink the given CmpInst into user blocks to reduce the number of virtual
1350/// registers that must be created and coalesced. This is a clear win except on
1351/// targets with multiple condition code registers (PowerPC), where it might
1352/// lose; some adjustment may be wanted there.
1353///
1354/// Return true if any changes are made.
1355static bool sinkCmpExpression(CmpInst *Cmp, const TargetLowering &TLI) {
1356 if (TLI.hasMultipleConditionRegisters())
1357 return false;
1358
1359 // Avoid sinking soft-FP comparisons, since this can move them into a loop.
1360 if (TLI.useSoftFloat() && isa<FCmpInst>(Cmp))
1361 return false;
1362
1363 // Only insert a cmp in each block once.
1364 DenseMap<BasicBlock*, CmpInst*> InsertedCmps;
1365
1366 bool MadeChange = false;
1367 for (Value::user_iterator UI = Cmp->user_begin(), E = Cmp->user_end();
1368 UI != E; ) {
1369 Use &TheUse = UI.getUse();
1370 Instruction *User = cast<Instruction>(*UI);
1371
1372 // Preincrement use iterator so we don't invalidate it.
1373 ++UI;
1374
1375 // Don't bother for PHI nodes.
1376 if (isa<PHINode>(User))
1377 continue;
1378
1379 // Figure out which BB this cmp is used in.
1380 BasicBlock *UserBB = User->getParent();
1381 BasicBlock *DefBB = Cmp->getParent();
1382
1383 // If this user is in the same block as the cmp, don't change the cmp.
1384 if (UserBB == DefBB) continue;
1385
1386 // If we have already inserted a cmp into this block, use it.
1387 CmpInst *&InsertedCmp = InsertedCmps[UserBB];
1388
1389 if (!InsertedCmp) {
1390 BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
1391 assert(InsertPt != UserBB->end())((InsertPt != UserBB->end()) ? static_cast<void> (0)
: __assert_fail ("InsertPt != UserBB->end()", "/build/llvm-toolchain-snapshot-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 1391, __PRETTY_FUNCTION__))
;
1392 InsertedCmp =
1393 CmpInst::Create(Cmp->getOpcode(), Cmp->getPredicate(),
1394 Cmp->getOperand(0), Cmp->getOperand(1), "",
1395 &*InsertPt);
1396 // Propagate the debug info.
1397 InsertedCmp->setDebugLoc(Cmp->getDebugLoc());
1398 }
1399
1400 // Replace a use of the cmp with a use of the new cmp.
1401 TheUse = InsertedCmp;
1402 MadeChange = true;
1403 ++NumCmpUses;
1404 }
1405
1406 // If we removed all uses, nuke the cmp.
1407 if (Cmp->use_empty()) {
1408 Cmp->eraseFromParent();
1409 MadeChange = true;
1410 }
1411
1412 return MadeChange;
1413}
1414
1415/// For pattern like:
1416///
1417/// DomCond = icmp sgt/slt CmpOp0, CmpOp1 (might not be in DomBB)
1418/// ...
1419/// DomBB:
1420/// ...
1421/// br DomCond, TrueBB, CmpBB
1422/// CmpBB: (with DomBB being the single predecessor)
1423/// ...
1424/// Cmp = icmp eq CmpOp0, CmpOp1
1425/// ...
1426///
1427/// It would use two comparison on targets that lowering of icmp sgt/slt is
1428/// different from lowering of icmp eq (PowerPC). This function try to convert
1429/// 'Cmp = icmp eq CmpOp0, CmpOp1' to ' Cmp = icmp slt/sgt CmpOp0, CmpOp1'.
1430/// After that, DomCond and Cmp can use the same comparison so reduce one
1431/// comparison.
1432///
1433/// Return true if any changes are made.
1434static bool foldICmpWithDominatingICmp(CmpInst *Cmp,
1435 const TargetLowering &TLI) {
1436 if (!EnableICMP_EQToICMP_ST && TLI.isEqualityCmpFoldedWithSignedCmp())
1437 return false;
1438
1439 ICmpInst::Predicate Pred = Cmp->getPredicate();
1440 if (Pred != ICmpInst::ICMP_EQ)
1441 return false;
1442
1443 // If icmp eq has users other than BranchInst and SelectInst, converting it to
1444 // icmp slt/sgt would introduce more redundant LLVM IR.
1445 for (User *U : Cmp->users()) {
1446 if (isa<BranchInst>(U))
1447 continue;
1448 if (isa<SelectInst>(U) && cast<SelectInst>(U)->getCondition() == Cmp)
1449 continue;
1450 return false;
1451 }
1452
1453 // This is a cheap/incomplete check for dominance - just match a single
1454 // predecessor with a conditional branch.
1455 BasicBlock *CmpBB = Cmp->getParent();
1456 BasicBlock *DomBB = CmpBB->getSinglePredecessor();
1457 if (!DomBB)
1458 return false;
1459
1460 // We want to ensure that the only way control gets to the comparison of
1461 // interest is that a less/greater than comparison on the same operands is
1462 // false.
1463 Value *DomCond;
1464 BasicBlock *TrueBB, *FalseBB;
1465 if (!match(DomBB->getTerminator(), m_Br(m_Value(DomCond), TrueBB, FalseBB)))
1466 return false;
1467 if (CmpBB != FalseBB)
1468 return false;
1469
1470 Value *CmpOp0 = Cmp->getOperand(0), *CmpOp1 = Cmp->getOperand(1);
1471 ICmpInst::Predicate DomPred;
1472 if (!match(DomCond, m_ICmp(DomPred, m_Specific(CmpOp0), m_Specific(CmpOp1))))
1473 return false;
1474 if (DomPred != ICmpInst::ICMP_SGT && DomPred != ICmpInst::ICMP_SLT)
1475 return false;
1476
1477 // Convert the equality comparison to the opposite of the dominating
1478 // comparison and swap the direction for all branch/select users.
1479 // We have conceptually converted:
1480 // Res = (a < b) ? <LT_RES> : (a == b) ? <EQ_RES> : <GT_RES>;
1481 // to
1482 // Res = (a < b) ? <LT_RES> : (a > b) ? <GT_RES> : <EQ_RES>;
1483 // And similarly for branches.
1484 for (User *U : Cmp->users()) {
1485 if (auto *BI = dyn_cast<BranchInst>(U)) {
1486 assert(BI->isConditional() && "Must be conditional")((BI->isConditional() && "Must be conditional") ? static_cast
<void> (0) : __assert_fail ("BI->isConditional() && \"Must be conditional\""
, "/build/llvm-toolchain-snapshot-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 1486, __PRETTY_FUNCTION__))
;
1487 BI->swapSuccessors();
1488 continue;
1489 }
1490 if (auto *SI = dyn_cast<SelectInst>(U)) {
1491 // Swap operands
1492 SI->swapValues();
1493 SI->swapProfMetadata();
1494 continue;
1495 }
1496 llvm_unreachable("Must be a branch or a select")::llvm::llvm_unreachable_internal("Must be a branch or a select"
, "/build/llvm-toolchain-snapshot-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 1496)
;
1497 }
1498 Cmp->setPredicate(CmpInst::getSwappedPredicate(DomPred));
1499 return true;
1500}
1501
1502bool CodeGenPrepare::optimizeCmp(CmpInst *Cmp, bool &ModifiedDT) {
1503 if (sinkCmpExpression(Cmp, *TLI))
1504 return true;
1505
1506 if (combineToUAddWithOverflow(Cmp, ModifiedDT))
1507 return true;
1508
1509 if (combineToUSubWithOverflow(Cmp, ModifiedDT))
1510 return true;
1511
1512 if (foldICmpWithDominatingICmp(Cmp, *TLI))
1513 return true;
1514
1515 return false;
1516}
1517
1518/// Duplicate and sink the given 'and' instruction into user blocks where it is
1519/// used in a compare to allow isel to generate better code for targets where
1520/// this operation can be combined.
1521///
1522/// Return true if any changes are made.
1523static bool sinkAndCmp0Expression(Instruction *AndI,
1524 const TargetLowering &TLI,
1525 SetOfInstrs &InsertedInsts) {
1526 // Double-check that we're not trying to optimize an instruction that was
1527 // already optimized by some other part of this pass.
1528 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-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 1529, __PRETTY_FUNCTION__))
1529 "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-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 1529, __PRETTY_FUNCTION__))
;
1530 (void) InsertedInsts;
1531
1532 // Nothing to do for single use in same basic block.
1533 if (AndI->hasOneUse() &&
1534 AndI->getParent() == cast<Instruction>(*AndI->user_begin())->getParent())
1535 return false;
1536
1537 // Try to avoid cases where sinking/duplicating is likely to increase register
1538 // pressure.
1539 if (!isa<ConstantInt>(AndI->getOperand(0)) &&
1540 !isa<ConstantInt>(AndI->getOperand(1)) &&
1541 AndI->getOperand(0)->hasOneUse() && AndI->getOperand(1)->hasOneUse())
1542 return false;
1543
1544 for (auto *U : AndI->users()) {
1545 Instruction *User = cast<Instruction>(U);
1546
1547 // Only sink 'and' feeding icmp with 0.
1548 if (!isa<ICmpInst>(User))
1549 return false;
1550
1551 auto *CmpC = dyn_cast<ConstantInt>(User->getOperand(1));
1552 if (!CmpC || !CmpC->isZero())
1553 return false;
1554 }
1555
1556 if (!TLI.isMaskAndCmp0FoldingBeneficial(*AndI))
1557 return false;
1558
1559 LLVM_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)
;
1560 LLVM_DEBUG(AndI->getParent()->dump())do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { AndI->getParent()->dump(); } } while
(false)
;
1561
1562 // Push the 'and' into the same block as the icmp 0. There should only be
1563 // one (icmp (and, 0)) in each block, since CSE/GVN should have removed any
1564 // others, so we don't need to keep track of which BBs we insert into.
1565 for (Value::user_iterator UI = AndI->user_begin(), E = AndI->user_end();
1566 UI != E; ) {
1567 Use &TheUse = UI.getUse();
1568 Instruction *User = cast<Instruction>(*UI);
1569
1570 // Preincrement use iterator so we don't invalidate it.
1571 ++UI;
1572
1573 LLVM_DEBUG(dbgs() << "sinking 'and' use: " << *User << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "sinking 'and' use: " <<
*User << "\n"; } } while (false)
;
1574
1575 // Keep the 'and' in the same place if the use is already in the same block.
1576 Instruction *InsertPt =
1577 User->getParent() == AndI->getParent() ? AndI : User;
1578 Instruction *InsertedAnd =
1579 BinaryOperator::Create(Instruction::And, AndI->getOperand(0),
1580 AndI->getOperand(1), "", InsertPt);
1581 // Propagate the debug info.
1582 InsertedAnd->setDebugLoc(AndI->getDebugLoc());
1583
1584 // Replace a use of the 'and' with a use of the new 'and'.
1585 TheUse = InsertedAnd;
1586 ++NumAndUses;
1587 LLVM_DEBUG(User->getParent()->dump())do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { User->getParent()->dump(); } } while
(false)
;
1588 }
1589
1590 // We removed all uses, nuke the and.
1591 AndI->eraseFromParent();
1592 return true;
1593}
1594
1595/// Check if the candidates could be combined with a shift instruction, which
1596/// includes:
1597/// 1. Truncate instruction
1598/// 2. And instruction and the imm is a mask of the low bits:
1599/// imm & (imm+1) == 0
1600static bool isExtractBitsCandidateUse(Instruction *User) {
1601 if (!isa<TruncInst>(User)) {
1602 if (User->getOpcode() != Instruction::And ||
1603 !isa<ConstantInt>(User->getOperand(1)))
1604 return false;
1605
1606 const APInt &Cimm = cast<ConstantInt>(User->getOperand(1))->getValue();
1607
1608 if ((Cimm & (Cimm + 1)).getBoolValue())
1609 return false;
1610 }
1611 return true;
1612}
1613
1614/// Sink both shift and truncate instruction to the use of truncate's BB.
1615static bool
1616SinkShiftAndTruncate(BinaryOperator *ShiftI, Instruction *User, ConstantInt *CI,
1617 DenseMap<BasicBlock *, BinaryOperator *> &InsertedShifts,
1618 const TargetLowering &TLI, const DataLayout &DL) {
1619 BasicBlock *UserBB = User->getParent();
1620 DenseMap<BasicBlock *, CastInst *> InsertedTruncs;
1621 auto *TruncI = cast<TruncInst>(User);
1622 bool MadeChange = false;
1623
1624 for (Value::user_iterator TruncUI = TruncI->user_begin(),
1625 TruncE = TruncI->user_end();
1626 TruncUI != TruncE;) {
1627
1628 Use &TruncTheUse = TruncUI.getUse();
1629 Instruction *TruncUser = cast<Instruction>(*TruncUI);
1630 // Preincrement use iterator so we don't invalidate it.
1631
1632 ++TruncUI;
1633
1634 int ISDOpcode = TLI.InstructionOpcodeToISD(TruncUser->getOpcode());
1635 if (!ISDOpcode)
1636 continue;
1637
1638 // If the use is actually a legal node, there will not be an
1639 // implicit truncate.
1640 // FIXME: always querying the result type is just an
1641 // approximation; some nodes' legality is determined by the
1642 // operand or other means. There's no good way to find out though.
1643 if (TLI.isOperationLegalOrCustom(
1644 ISDOpcode, TLI.getValueType(DL, TruncUser->getType(), true)))
1645 continue;
1646
1647 // Don't bother for PHI nodes.
1648 if (isa<PHINode>(TruncUser))
1649 continue;
1650
1651 BasicBlock *TruncUserBB = TruncUser->getParent();
1652
1653 if (UserBB == TruncUserBB)
1654 continue;
1655
1656 BinaryOperator *&InsertedShift = InsertedShifts[TruncUserBB];
1657 CastInst *&InsertedTrunc = InsertedTruncs[TruncUserBB];
1658
1659 if (!InsertedShift && !InsertedTrunc) {
1660 BasicBlock::iterator InsertPt = TruncUserBB->getFirstInsertionPt();
1661 assert(InsertPt != TruncUserBB->end())((InsertPt != TruncUserBB->end()) ? static_cast<void>
(0) : __assert_fail ("InsertPt != TruncUserBB->end()", "/build/llvm-toolchain-snapshot-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 1661, __PRETTY_FUNCTION__))
;
1662 // Sink the shift
1663 if (ShiftI->getOpcode() == Instruction::AShr)
1664 InsertedShift = BinaryOperator::CreateAShr(ShiftI->getOperand(0), CI,
1665 "", &*InsertPt);
1666 else
1667 InsertedShift = BinaryOperator::CreateLShr(ShiftI->getOperand(0), CI,
1668 "", &*InsertPt);
1669 InsertedShift->setDebugLoc(ShiftI->getDebugLoc());
1670
1671 // Sink the trunc
1672 BasicBlock::iterator TruncInsertPt = TruncUserBB->getFirstInsertionPt();
1673 TruncInsertPt++;
1674 assert(TruncInsertPt != TruncUserBB->end())((TruncInsertPt != TruncUserBB->end()) ? static_cast<void
> (0) : __assert_fail ("TruncInsertPt != TruncUserBB->end()"
, "/build/llvm-toolchain-snapshot-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 1674, __PRETTY_FUNCTION__))
;
1675
1676 InsertedTrunc = CastInst::Create(TruncI->getOpcode(), InsertedShift,
1677 TruncI->getType(), "", &*TruncInsertPt);
1678 InsertedTrunc->setDebugLoc(TruncI->getDebugLoc());
1679
1680 MadeChange = true;
1681
1682 TruncTheUse = InsertedTrunc;
1683 }
1684 }
1685 return MadeChange;
1686}
1687
1688/// Sink the shift *right* instruction into user blocks if the uses could
1689/// potentially be combined with this shift instruction and generate BitExtract
1690/// instruction. It will only be applied if the architecture supports BitExtract
1691/// instruction. Here is an example:
1692/// BB1:
1693/// %x.extract.shift = lshr i64 %arg1, 32
1694/// BB2:
1695/// %x.extract.trunc = trunc i64 %x.extract.shift to i16
1696/// ==>
1697///
1698/// BB2:
1699/// %x.extract.shift.1 = lshr i64 %arg1, 32
1700/// %x.extract.trunc = trunc i64 %x.extract.shift.1 to i16
1701///
1702/// CodeGen will recognize the pattern in BB2 and generate BitExtract
1703/// instruction.
1704/// Return true if any changes are made.
1705static bool OptimizeExtractBits(BinaryOperator *ShiftI, ConstantInt *CI,
1706 const TargetLowering &TLI,
1707 const DataLayout &DL) {
1708 BasicBlock *DefBB = ShiftI->getParent();
1709
1710 /// Only insert instructions in each block once.
1711 DenseMap<BasicBlock *, BinaryOperator *> InsertedShifts;
1712
1713 bool shiftIsLegal = TLI.isTypeLegal(TLI.getValueType(DL, ShiftI->getType()));
1714
1715 bool MadeChange = false;
1716 for (Value::user_iterator UI = ShiftI->user_begin(), E = ShiftI->user_end();
1717 UI != E;) {
1718 Use &TheUse = UI.getUse();
1719 Instruction *User = cast<Instruction>(*UI);
1720 // Preincrement use iterator so we don't invalidate it.
1721 ++UI;
1722
1723 // Don't bother for PHI nodes.
1724 if (isa<PHINode>(User))
1725 continue;
1726
1727 if (!isExtractBitsCandidateUse(User))
1728 continue;
1729
1730 BasicBlock *UserBB = User->getParent();
1731
1732 if (UserBB == DefBB) {
1733 // If the shift and truncate instruction are in the same BB. The use of
1734 // the truncate(TruncUse) may still introduce another truncate if not
1735 // legal. In this case, we would like to sink both shift and truncate
1736 // instruction to the BB of TruncUse.
1737 // for example:
1738 // BB1:
1739 // i64 shift.result = lshr i64 opnd, imm
1740 // trunc.result = trunc shift.result to i16
1741 //
1742 // BB2:
1743 // ----> We will have an implicit truncate here if the architecture does
1744 // not have i16 compare.
1745 // cmp i16 trunc.result, opnd2
1746 //
1747 if (isa<TruncInst>(User) && shiftIsLegal
1748 // If the type of the truncate is legal, no truncate will be
1749 // introduced in other basic blocks.
1750 &&
1751 (!TLI.isTypeLegal(TLI.getValueType(DL, User->getType()))))
1752 MadeChange =
1753 SinkShiftAndTruncate(ShiftI, User, CI, InsertedShifts, TLI, DL);
1754
1755 continue;
1756 }
1757 // If we have already inserted a shift into this block, use it.
1758 BinaryOperator *&InsertedShift = InsertedShifts[UserBB];
1759
1760 if (!InsertedShift) {
1761 BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
1762 assert(InsertPt != UserBB->end())((InsertPt != UserBB->end()) ? static_cast<void> (0)
: __assert_fail ("InsertPt != UserBB->end()", "/build/llvm-toolchain-snapshot-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 1762, __PRETTY_FUNCTION__))
;
1763
1764 if (ShiftI->getOpcode() == Instruction::AShr)
1765 InsertedShift = BinaryOperator::CreateAShr(ShiftI->getOperand(0), CI,
1766 "", &*InsertPt);
1767 else
1768 InsertedShift = BinaryOperator::CreateLShr(ShiftI->getOperand(0), CI,
1769 "", &*InsertPt);
1770 InsertedShift->setDebugLoc(ShiftI->getDebugLoc());
1771
1772 MadeChange = true;
1773 }
1774
1775 // Replace a use of the shift with a use of the new shift.
1776 TheUse = InsertedShift;
1777 }
1778
1779 // If we removed all uses, or there are none, nuke the shift.
1780 if (ShiftI->use_empty()) {
1781 salvageDebugInfo(*ShiftI);
1782 ShiftI->eraseFromParent();
1783 MadeChange = true;
1784 }
1785
1786 return MadeChange;
1787}
1788
1789/// If counting leading or trailing zeros is an expensive operation and a zero
1790/// input is defined, add a check for zero to avoid calling the intrinsic.
1791///
1792/// We want to transform:
1793/// %z = call i64 @llvm.cttz.i64(i64 %A, i1 false)
1794///
1795/// into:
1796/// entry:
1797/// %cmpz = icmp eq i64 %A, 0
1798/// br i1 %cmpz, label %cond.end, label %cond.false
1799/// cond.false:
1800/// %z = call i64 @llvm.cttz.i64(i64 %A, i1 true)
1801/// br label %cond.end
1802/// cond.end:
1803/// %ctz = phi i64 [ 64, %entry ], [ %z, %cond.false ]
1804///
1805/// If the transform is performed, return true and set ModifiedDT to true.
1806static bool despeculateCountZeros(IntrinsicInst *CountZeros,
1807 const TargetLowering *TLI,
1808 const DataLayout *DL,
1809 bool &ModifiedDT) {
1810 if (!TLI || !DL)
1811 return false;
1812
1813 // If a zero input is undefined, it doesn't make sense to despeculate that.
1814 if (match(CountZeros->getOperand(1), m_One()))
1815 return false;
1816
1817 // If it's cheap to speculate, there's nothing to do.
1818 auto IntrinsicID = CountZeros->getIntrinsicID();
1819 if ((IntrinsicID == Intrinsic::cttz && TLI->isCheapToSpeculateCttz()) ||
1820 (IntrinsicID == Intrinsic::ctlz && TLI->isCheapToSpeculateCtlz()))
1821 return false;
1822
1823 // Only handle legal scalar cases. Anything else requires too much work.
1824 Type *Ty = CountZeros->getType();
1825 unsigned SizeInBits = Ty->getPrimitiveSizeInBits();
1826 if (Ty->isVectorTy() || SizeInBits > DL->getLargestLegalIntTypeSizeInBits())
1827 return false;
1828
1829 // The intrinsic will be sunk behind a compare against zero and branch.
1830 BasicBlock *StartBlock = CountZeros->getParent();
1831 BasicBlock *CallBlock = StartBlock->splitBasicBlock(CountZeros, "cond.false");
1832
1833 // Create another block after the count zero intrinsic. A PHI will be added
1834 // in this block to select the result of the intrinsic or the bit-width
1835 // constant if the input to the intrinsic is zero.
1836 BasicBlock::iterator SplitPt = ++(BasicBlock::iterator(CountZeros));
1837 BasicBlock *EndBlock = CallBlock->splitBasicBlock(SplitPt, "cond.end");
1838
1839 // Set up a builder to create a compare, conditional branch, and PHI.
1840 IRBuilder<> Builder(CountZeros->getContext());
1841 Builder.SetInsertPoint(StartBlock->getTerminator());
1842 Builder.SetCurrentDebugLocation(CountZeros->getDebugLoc());
1843
1844 // Replace the unconditional branch that was created by the first split with
1845 // a compare against zero and a conditional branch.
1846 Value *Zero = Constant::getNullValue(Ty);
1847 Value *Cmp = Builder.CreateICmpEQ(CountZeros->getOperand(0), Zero, "cmpz");
1848 Builder.CreateCondBr(Cmp, EndBlock, CallBlock);
1849 StartBlock->getTerminator()->eraseFromParent();
1850
1851 // Create a PHI in the end block to select either the output of the intrinsic
1852 // or the bit width of the operand.
1853 Builder.SetInsertPoint(&EndBlock->front());
1854 PHINode *PN = Builder.CreatePHI(Ty, 2, "ctz");
1855 CountZeros->replaceAllUsesWith(PN);
1856 Value *BitWidth = Builder.getInt(APInt(SizeInBits, SizeInBits));
1857 PN->addIncoming(BitWidth, StartBlock);
1858 PN->addIncoming(CountZeros, CallBlock);
1859
1860 // We are explicitly handling the zero case, so we can set the intrinsic's
1861 // undefined zero argument to 'true'. This will also prevent reprocessing the
1862 // intrinsic; we only despeculate when a zero input is defined.
1863 CountZeros->setArgOperand(1, Builder.getTrue());
1864 ModifiedDT = true;
1865 return true;
1866}
1867
1868bool CodeGenPrepare::optimizeCallInst(CallInst *CI, bool &ModifiedDT) {
1869 BasicBlock *BB = CI->getParent();
1870
1871 // Lower inline assembly if we can.
1872 // If we found an inline asm expession, and if the target knows how to
1873 // lower it to normal LLVM code, do so now.
1874 if (TLI && isa<InlineAsm>(CI->getCalledValue())) {
1875 if (TLI->ExpandInlineAsm(CI)) {
1876 // Avoid invalidating the iterator.
1877 CurInstIterator = BB->begin();
1878 // Avoid processing instructions out of order, which could cause
1879 // reuse before a value is defined.
1880 SunkAddrs.clear();
1881 return true;
1882 }
1883 // Sink address computing for memory operands into the block.
1884 if (optimizeInlineAsmInst(CI))
1885 return true;
1886 }
1887
1888 // Align the pointer arguments to this call if the target thinks it's a good
1889 // idea
1890 unsigned MinSize, PrefAlign;
1891 if (TLI && TLI->shouldAlignPointerArgs(CI, MinSize, PrefAlign)) {
1892 for (auto &Arg : CI->arg_operands()) {
1893 // We want to align both objects whose address is used directly and
1894 // objects whose address is used in casts and GEPs, though it only makes
1895 // sense for GEPs if the offset is a multiple of the desired alignment and
1896 // if size - offset meets the size threshold.
1897 if (!Arg->getType()->isPointerTy())
1898 continue;
1899 APInt Offset(DL->getIndexSizeInBits(
1900 cast<PointerType>(Arg->getType())->getAddressSpace()),
1901 0);
1902 Value *Val = Arg->stripAndAccumulateInBoundsConstantOffsets(*DL, Offset);
1903 uint64_t Offset2 = Offset.getLimitedValue();
1904 if ((Offset2 & (PrefAlign-1)) != 0)
1905 continue;
1906 AllocaInst *AI;
1907 if ((AI = dyn_cast<AllocaInst>(Val)) && AI->getAlignment() < PrefAlign &&
1908 DL->getTypeAllocSize(AI->getAllocatedType()) >= MinSize + Offset2)
1909 AI->setAlignment(MaybeAlign(PrefAlign));
1910 // Global variables can only be aligned if they are defined in this
1911 // object (i.e. they are uniquely initialized in this object), and
1912 // over-aligning global variables that have an explicit section is
1913 // forbidden.
1914 GlobalVariable *GV;
1915 if ((GV = dyn_cast<GlobalVariable>(Val)) && GV->canIncreaseAlignment() &&
1916 GV->getPointerAlignment(*DL) < PrefAlign &&
1917 DL->getTypeAllocSize(GV->getValueType()) >=
1918 MinSize + Offset2)
1919 GV->setAlignment(MaybeAlign(PrefAlign));
1920 }
1921 // If this is a memcpy (or similar) then we may be able to improve the
1922 // alignment
1923 if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(CI)) {
1924 unsigned DestAlign = getKnownAlignment(MI->getDest(), *DL);
1925 if (DestAlign > MI->getDestAlignment())
1926 MI->setDestAlignment(DestAlign);
1927 if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(MI)) {
1928 unsigned SrcAlign = getKnownAlignment(MTI->getSource(), *DL);
1929 if (SrcAlign > MTI->getSourceAlignment())
1930 MTI->setSourceAlignment(SrcAlign);
1931 }
1932 }
1933 }
1934
1935 // If we have a cold call site, try to sink addressing computation into the
1936 // cold block. This interacts with our handling for loads and stores to
1937 // ensure that we can fold all uses of a potential addressing computation
1938 // into their uses. TODO: generalize this to work over profiling data
1939 if (!OptSize && CI->hasFnAttr(Attribute::Cold))
1940 for (auto &Arg : CI->arg_operands()) {
1941 if (!Arg->getType()->isPointerTy())
1942 continue;
1943 unsigned AS = Arg->getType()->getPointerAddressSpace();
1944 return optimizeMemoryInst(CI, Arg, Arg->getType(), AS);
1945 }
1946
1947 IntrinsicInst *II = dyn_cast<IntrinsicInst>(CI);
1948 if (II) {
1949 switch (II->getIntrinsicID()) {
1950 default: break;
1951 case Intrinsic::experimental_widenable_condition: {
1952 // Give up on future widening oppurtunties so that we can fold away dead
1953 // paths and merge blocks before going into block-local instruction
1954 // selection.
1955 if (II->use_empty()) {
1956 II->eraseFromParent();
1957 return true;
1958 }
1959 Constant *RetVal = ConstantInt::getTrue(II->getContext());
1960 resetIteratorIfInvalidatedWhileCalling(BB, [&]() {
1961 replaceAndRecursivelySimplify(CI, RetVal, TLInfo, nullptr);
1962 });
1963 return true;
1964 }
1965 case Intrinsic::objectsize:
1966 llvm_unreachable("llvm.objectsize.* should have been lowered already")::llvm::llvm_unreachable_internal("llvm.objectsize.* should have been lowered already"
, "/build/llvm-toolchain-snapshot-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 1966)
;
1967 case Intrinsic::is_constant:
1968 llvm_unreachable("llvm.is.constant.* should have been lowered already")::llvm::llvm_unreachable_internal("llvm.is.constant.* should have been lowered already"
, "/build/llvm-toolchain-snapshot-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 1968)
;
1969 case Intrinsic::aarch64_stlxr:
1970 case Intrinsic::aarch64_stxr: {
1971 ZExtInst *ExtVal = dyn_cast<ZExtInst>(CI->getArgOperand(0));
1972 if (!ExtVal || !ExtVal->hasOneUse() ||
1973 ExtVal->getParent() == CI->getParent())
1974 return false;
1975 // Sink a zext feeding stlxr/stxr before it, so it can be folded into it.
1976 ExtVal->moveBefore(CI);
1977 // Mark this instruction as "inserted by CGP", so that other
1978 // optimizations don't touch it.
1979 InsertedInsts.insert(ExtVal);
1980 return true;
1981 }
1982
1983 case Intrinsic::launder_invariant_group:
1984 case Intrinsic::strip_invariant_group: {
1985 Value *ArgVal = II->getArgOperand(0);
1986 auto it = LargeOffsetGEPMap.find(II);
1987 if (it != LargeOffsetGEPMap.end()) {
1988 // Merge entries in LargeOffsetGEPMap to reflect the RAUW.
1989 // Make sure not to have to deal with iterator invalidation
1990 // after possibly adding ArgVal to LargeOffsetGEPMap.
1991 auto GEPs = std::move(it->second);
1992 LargeOffsetGEPMap[ArgVal].append(GEPs.begin(), GEPs.end());
1993 LargeOffsetGEPMap.erase(II);
1994 }
1995
1996 II->replaceAllUsesWith(ArgVal);
1997 II->eraseFromParent();
1998 return true;
1999 }
2000 case Intrinsic::cttz:
2001 case Intrinsic::ctlz:
2002 // If counting zeros is expensive, try to avoid it.
2003 return despeculateCountZeros(II, TLI, DL, ModifiedDT);
2004 }
2005
2006 if (TLI) {
2007 SmallVector<Value*, 2> PtrOps;
2008 Type *AccessTy;
2009 if (TLI->getAddrModeArguments(II, PtrOps, AccessTy))
2010 while (!PtrOps.empty()) {
2011 Value *PtrVal = PtrOps.pop_back_val();
2012 unsigned AS = PtrVal->getType()->getPointerAddressSpace();
2013 if (optimizeMemoryInst(II, PtrVal, AccessTy, AS))
2014 return true;
2015 }
2016 }
2017 }
2018
2019 // From here on out we're working with named functions.
2020 if (!CI->getCalledFunction()) return false;
2021
2022 // Lower all default uses of _chk calls. This is very similar
2023 // to what InstCombineCalls does, but here we are only lowering calls
2024 // to fortified library functions (e.g. __memcpy_chk) that have the default
2025 // "don't know" as the objectsize. Anything else should be left alone.
2026 FortifiedLibCallSimplifier Simplifier(TLInfo, true);
2027 if (Value *V = Simplifier.optimizeCall(CI)) {
2028 CI->replaceAllUsesWith(V);
2029 CI->eraseFromParent();
2030 return true;
2031 }
2032
2033 return false;
2034}
2035
2036/// Look for opportunities to duplicate return instructions to the predecessor
2037/// to enable tail call optimizations. The case it is currently looking for is:
2038/// @code
2039/// bb0:
2040/// %tmp0 = tail call i32 @f0()
2041/// br label %return
2042/// bb1:
2043/// %tmp1 = tail call i32 @f1()
2044/// br label %return
2045/// bb2:
2046/// %tmp2 = tail call i32 @f2()
2047/// br label %return
2048/// return:
2049/// %retval = phi i32 [ %tmp0, %bb0 ], [ %tmp1, %bb1 ], [ %tmp2, %bb2 ]
2050/// ret i32 %retval
2051/// @endcode
2052///
2053/// =>
2054///
2055/// @code
2056/// bb0:
2057/// %tmp0 = tail call i32 @f0()
2058/// ret i32 %tmp0
2059/// bb1:
2060/// %tmp1 = tail call i32 @f1()
2061/// ret i32 %tmp1
2062/// bb2:
2063/// %tmp2 = tail call i32 @f2()
2064/// ret i32 %tmp2
2065/// @endcode
2066bool CodeGenPrepare::dupRetToEnableTailCallOpts(BasicBlock *BB, bool &ModifiedDT) {
2067 if (!TLI)
2068 return false;
2069
2070 ReturnInst *RetI = dyn_cast<ReturnInst>(BB->getTerminator());
2071 if (!RetI)
2072 return false;
2073
2074 PHINode *PN = nullptr;
2075 BitCastInst *BCI = nullptr;
2076 Value *V = RetI->getReturnValue();
2077 if (V) {
2078 BCI = dyn_cast<BitCastInst>(V);
2079 if (BCI)
2080 V = BCI->getOperand(0);
2081
2082 PN = dyn_cast<PHINode>(V);
2083 if (!PN)
2084 return false;
2085 }
2086
2087 if (PN && PN->getParent() != BB)
2088 return false;
2089
2090 // Make sure there are no instructions between the PHI and return, or that the
2091 // return is the first instruction in the block.
2092 if (PN) {
2093 BasicBlock::iterator BI = BB->begin();
2094 // Skip over debug and the bitcast.
2095 do { ++BI; } while (isa<DbgInfoIntrinsic>(BI) || &*BI == BCI);
2096 if (&*BI != RetI)
2097 return false;
2098 } else {
2099 BasicBlock::iterator BI = BB->begin();
2100 while (isa<DbgInfoIntrinsic>(BI)) ++BI;
2101 if (&*BI != RetI)
2102 return false;
2103 }
2104
2105 /// Only dup the ReturnInst if the CallInst is likely to be emitted as a tail
2106 /// call.
2107 const Function *F = BB->getParent();
2108 SmallVector<BasicBlock*, 4> TailCallBBs;
2109 if (PN) {
2110 for (unsigned I = 0, E = PN->getNumIncomingValues(); I != E; ++I) {
2111 // Look through bitcasts.
2112 Value *IncomingVal = PN->getIncomingValue(I)->stripPointerCasts();
2113 CallInst *CI = dyn_cast<CallInst>(IncomingVal);
2114 BasicBlock *PredBB = PN->getIncomingBlock(I);
2115 // Make sure the phi value is indeed produced by the tail call.
2116 if (CI && CI->hasOneUse() && CI->getParent() == PredBB &&
2117 TLI->mayBeEmittedAsTailCall(CI) &&
2118 attributesPermitTailCall(F, CI, RetI, *TLI))
2119 TailCallBBs.push_back(PredBB);
2120 }
2121 } else {
2122 SmallPtrSet<BasicBlock*, 4> VisitedBBs;
2123 for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB); PI != PE; ++PI) {
2124 if (!VisitedBBs.insert(*PI).second)
2125 continue;
2126
2127 BasicBlock::InstListType &InstList = (*PI)->getInstList();
2128 BasicBlock::InstListType::reverse_iterator RI = InstList.rbegin();
2129 BasicBlock::InstListType::reverse_iterator RE = InstList.rend();
2130 do { ++RI; } while (RI != RE && isa<DbgInfoIntrinsic>(&*RI));
2131 if (RI == RE)
2132 continue;
2133
2134 CallInst *CI = dyn_cast<CallInst>(&*RI);
2135 if (CI && CI->use_empty() && TLI->mayBeEmittedAsTailCall(CI) &&
2136 attributesPermitTailCall(F, CI, RetI, *TLI))
2137 TailCallBBs.push_back(*PI);
2138 }
2139 }
2140
2141 bool Changed = false;
2142 for (auto const &TailCallBB : TailCallBBs) {
2143 // Make sure the call instruction is followed by an unconditional branch to
2144 // the return block.
2145 BranchInst *BI = dyn_cast<BranchInst>(TailCallBB->getTerminator());
2146 if (!BI || !BI->isUnconditional() || BI->getSuccessor(0) != BB)
2147 continue;
2148
2149 // Duplicate the return into TailCallBB.
2150 (void)FoldReturnIntoUncondBranch(RetI, BB, TailCallBB);
2151 ModifiedDT = Changed = true;
2152 ++NumRetsDup;
2153 }
2154
2155 // If we eliminated all predecessors of the block, delete the block now.
2156 if (Changed && !BB->hasAddressTaken() && pred_begin(BB) == pred_end(BB))
2157 BB->eraseFromParent();
2158
2159 return Changed;
2160}
2161
2162//===----------------------------------------------------------------------===//
2163// Memory Optimization
2164//===----------------------------------------------------------------------===//
2165
2166namespace {
2167
2168/// This is an extended version of TargetLowering::AddrMode
2169/// which holds actual Value*'s for register values.
2170struct ExtAddrMode : public TargetLowering::AddrMode {
2171 Value *BaseReg = nullptr;
2172 Value *ScaledReg = nullptr;
2173 Value *OriginalValue = nullptr;
2174 bool InBounds = true;
2175
2176 enum FieldName {
2177 NoField = 0x00,
2178 BaseRegField = 0x01,
2179 BaseGVField = 0x02,
2180 BaseOffsField = 0x04,
2181 ScaledRegField = 0x08,
2182 ScaleField = 0x10,
2183 MultipleFields = 0xff
2184 };
2185
2186
2187 ExtAddrMode() = default;
2188
2189 void print(raw_ostream &OS) const;
2190 void dump() const;
2191
2192 FieldName compare(const ExtAddrMode &other) {
2193 // First check that the types are the same on each field, as differing types
2194 // is something we can't cope with later on.
2195 if (BaseReg && other.BaseReg &&
2196 BaseReg->getType() != other.BaseReg->getType())
2197 return MultipleFields;
2198 if (BaseGV && other.BaseGV &&
2199 BaseGV->getType() != other.BaseGV->getType())
2200 return MultipleFields;
2201 if (ScaledReg && other.ScaledReg &&
2202 ScaledReg->getType() != other.ScaledReg->getType())
2203 return MultipleFields;
2204
2205 // Conservatively reject 'inbounds' mismatches.
2206 if (InBounds != other.InBounds)
2207 return MultipleFields;
2208
2209 // Check each field to see if it differs.
2210 unsigned Result = NoField;
2211 if (BaseReg != other.BaseReg)
2212 Result |= BaseRegField;
2213 if (BaseGV != other.BaseGV)
2214 Result |= BaseGVField;
2215 if (BaseOffs != other.BaseOffs)
2216 Result |= BaseOffsField;
2217 if (ScaledReg != other.ScaledReg)
2218 Result |= ScaledRegField;
2219 // Don't count 0 as being a different scale, because that actually means
2220 // unscaled (which will already be counted by having no ScaledReg).
2221 if (Scale && other.Scale && Scale != other.Scale)
2222 Result |= ScaleField;
2223
2224 if (countPopulation(Result) > 1)
2225 return MultipleFields;
2226 else
2227 return static_cast<FieldName>(Result);
2228 }
2229
2230 // An AddrMode is trivial if it involves no calculation i.e. it is just a base
2231 // with no offset.
2232 bool isTrivial() {
2233 // An AddrMode is (BaseGV + BaseReg + BaseOffs + ScaleReg * Scale) so it is
2234 // trivial if at most one of these terms is nonzero, except that BaseGV and
2235 // BaseReg both being zero actually means a null pointer value, which we
2236 // consider to be 'non-zero' here.
2237 return !BaseOffs && !Scale && !(BaseGV && BaseReg);
2238 }
2239
2240 Value *GetFieldAsValue(FieldName Field, Type *IntPtrTy) {
2241 switch (Field) {
2242 default:
2243 return nullptr;
2244 case BaseRegField:
2245 return BaseReg;
2246 case BaseGVField:
2247 return BaseGV;
2248 case ScaledRegField:
2249 return ScaledReg;
2250 case BaseOffsField:
2251 return ConstantInt::get(IntPtrTy, BaseOffs);
2252 }
2253 }
2254
2255 void SetCombinedField(FieldName Field, Value *V,
2256 const SmallVectorImpl<ExtAddrMode> &AddrModes) {
2257 switch (Field) {
2258 default:
2259 llvm_unreachable("Unhandled fields are expected to be rejected earlier")::llvm::llvm_unreachable_internal("Unhandled fields are expected to be rejected earlier"
, "/build/llvm-toolchain-snapshot-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 2259)
;
2260 break;
2261 case ExtAddrMode::BaseRegField:
2262 BaseReg = V;
2263 break;
2264 case ExtAddrMode::BaseGVField:
2265 // A combined BaseGV is an Instruction, not a GlobalValue, so it goes
2266 // in the BaseReg field.
2267 assert(BaseReg == nullptr)((BaseReg == nullptr) ? static_cast<void> (0) : __assert_fail
("BaseReg == nullptr", "/build/llvm-toolchain-snapshot-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 2267, __PRETTY_FUNCTION__))
;
2268 BaseReg = V;
2269 BaseGV = nullptr;
2270 break;
2271 case ExtAddrMode::ScaledRegField:
2272 ScaledReg = V;
2273 // If we have a mix of scaled and unscaled addrmodes then we want scale
2274 // to be the scale and not zero.
2275 if (!Scale)
2276 for (const ExtAddrMode &AM : AddrModes)
2277 if (AM.Scale) {
2278 Scale = AM.Scale;
2279 break;
2280 }
2281 break;
2282 case ExtAddrMode::BaseOffsField:
2283 // The offset is no longer a constant, so it goes in ScaledReg with a
2284 // scale of 1.
2285 assert(ScaledReg == nullptr)((ScaledReg == nullptr) ? static_cast<void> (0) : __assert_fail
("ScaledReg == nullptr", "/build/llvm-toolchain-snapshot-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 2285, __PRETTY_FUNCTION__))
;
2286 ScaledReg = V;
2287 Scale = 1;
2288 BaseOffs = 0;
2289 break;
2290 }
2291 }
2292};
2293
2294} // end anonymous namespace
2295
2296#ifndef NDEBUG
2297static inline raw_ostream &operator<<(raw_ostream &OS, const ExtAddrMode &AM) {
2298 AM.print(OS);
2299 return OS;
2300}
2301#endif
2302
2303#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
2304void ExtAddrMode::print(raw_ostream &OS) const {
2305 bool NeedPlus = false;
2306 OS << "[";
2307 if (InBounds)
2308 OS << "inbounds ";
2309 if (BaseGV) {
2310 OS << (NeedPlus ? " + " : "")
2311 << "GV:";
2312 BaseGV->printAsOperand(OS, /*PrintType=*/false);
2313 NeedPlus = true;
2314 }
2315
2316 if (BaseOffs) {
2317 OS << (NeedPlus ? " + " : "")
2318 << BaseOffs;
2319 NeedPlus = true;
2320 }
2321
2322 if (BaseReg) {
2323 OS << (NeedPlus ? " + " : "")
2324 << "Base:";
2325 BaseReg->printAsOperand(OS, /*PrintType=*/false);
2326 NeedPlus = true;
2327 }
2328 if (Scale) {
2329 OS << (NeedPlus ? " + " : "")
2330 << Scale << "*";
2331 ScaledReg->printAsOperand(OS, /*PrintType=*/false);
2332 }
2333
2334 OS << ']';
2335}
2336
2337LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void ExtAddrMode::dump() const {
2338 print(dbgs());
2339 dbgs() << '\n';
2340}
2341#endif
2342
2343namespace {
2344
2345/// This class provides transaction based operation on the IR.
2346/// Every change made through this class is recorded in the internal state and
2347/// can be undone (rollback) until commit is called.
2348class TypePromotionTransaction {
2349 /// This represents the common interface of the individual transaction.
2350 /// Each class implements the logic for doing one specific modification on
2351 /// the IR via the TypePromotionTransaction.
2352 class TypePromotionAction {
2353 protected:
2354 /// The Instruction modified.
2355 Instruction *Inst;
2356
2357 public:
2358 /// Constructor of the action.
2359 /// The constructor performs the related action on the IR.
2360 TypePromotionAction(Instruction *Inst) : Inst(Inst) {}
2361
2362 virtual ~TypePromotionAction() = default;
2363
2364 /// Undo the modification done by this action.
2365 /// When this method is called, the IR must be in the same state as it was
2366 /// before this action was applied.
2367 /// \pre Undoing the action works if and only if the IR is in the exact same
2368 /// state as it was directly after this action was applied.
2369 virtual void undo() = 0;
2370
2371 /// Advocate every change made by this action.
2372 /// When the results on the IR of the action are to be kept, it is important
2373 /// to call this function, otherwise hidden information may be kept forever.
2374 virtual void commit() {
2375 // Nothing to be done, this action is not doing anything.
2376 }
2377 };
2378
2379 /// Utility to remember the position of an instruction.
2380 class InsertionHandler {
2381 /// Position of an instruction.
2382 /// Either an instruction:
2383 /// - Is the first in a basic block: BB is used.
2384 /// - Has a previous instruction: PrevInst is used.
2385 union {
2386 Instruction *PrevInst;
2387 BasicBlock *BB;
2388 } Point;
2389
2390 /// Remember whether or not the instruction had a previous instruction.
2391 bool HasPrevInstruction;
2392
2393 public:
2394 /// Record the position of \p Inst.
2395 InsertionHandler(Instruction *Inst) {
2396 BasicBlock::iterator It = Inst->getIterator();
2397 HasPrevInstruction = (It != (Inst->getParent()->begin()));
2398 if (HasPrevInstruction)
2399 Point.PrevInst = &*--It;
2400 else
2401 Point.BB = Inst->getParent();
2402 }
2403
2404 /// Insert \p Inst at the recorded position.
2405 void insert(Instruction *Inst) {
2406 if (HasPrevInstruction) {
2407 if (Inst->getParent())
2408 Inst->removeFromParent();
2409 Inst->insertAfter(Point.PrevInst);
2410 } else {
2411 Instruction *Position = &*Point.BB->getFirstInsertionPt();
2412 if (Inst->getParent())
2413 Inst->moveBefore(Position);
2414 else
2415 Inst->insertBefore(Position);
2416 }
2417 }
2418 };
2419
2420 /// Move an instruction before another.
2421 class InstructionMoveBefore : public TypePromotionAction {
2422 /// Original position of the instruction.
2423 InsertionHandler Position;
2424
2425 public:
2426 /// Move \p Inst before \p Before.
2427 InstructionMoveBefore(Instruction *Inst, Instruction *Before)
2428 : TypePromotionAction(Inst), Position(Inst) {
2429 LLVM_DEBUG(dbgs() << "Do: move: " << *Inst << "\nbefore: " << *Beforedo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: move: " << *
Inst << "\nbefore: " << *Before << "\n"; } }
while (false)
2430 << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: move: " << *
Inst << "\nbefore: " << *Before << "\n"; } }
while (false)
;
2431 Inst->moveBefore(Before);
2432 }
2433
2434 /// Move the instruction back to its original position.
2435 void undo() override {
2436 LLVM_DEBUG(dbgs() << "Undo: moveBefore: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: moveBefore: " <<
*Inst << "\n"; } } while (false)
;
2437 Position.insert(Inst);
2438 }
2439 };
2440
2441 /// Set the operand of an instruction with a new value.
2442 class OperandSetter : public TypePromotionAction {
2443 /// Original operand of the instruction.
2444 Value *Origin;
2445
2446 /// Index of the modified instruction.
2447 unsigned Idx;
2448
2449 public:
2450 /// Set \p Idx operand of \p Inst with \p NewVal.
2451 OperandSetter(Instruction *Inst, unsigned Idx, Value *NewVal)
2452 : TypePromotionAction(Inst), Idx(Idx) {
2453 LLVM_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)
2454 << "for:" << *Inst << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: setOperand: " <<
Idx << "\n" << "for:" << *Inst << "\n"
<< "with:" << *NewVal << "\n"; } } while (
false)
2455 << "with:" << *NewVal << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: setOperand: " <<
Idx << "\n" << "for:" << *Inst << "\n"
<< "with:" << *NewVal << "\n"; } } while (
false)
;
2456 Origin = Inst->getOperand(Idx);
2457 Inst->setOperand(Idx, NewVal);
2458 }
2459
2460 /// Restore the original value of the instruction.
2461 void undo() override {
2462 LLVM_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)
2463 << "for: " << *Inst << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: setOperand:" <<
Idx << "\n" << "for: " << *Inst << "\n"
<< "with: " << *Origin << "\n"; } } while (
false)
2464 << "with: " << *Origin << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: setOperand:" <<
Idx << "\n" << "for: " << *Inst << "\n"
<< "with: " << *Origin << "\n"; } } while (
false)
;
2465 Inst->setOperand(Idx, Origin);
2466 }
2467 };
2468
2469 /// Hide the operands of an instruction.
2470 /// Do as if this instruction was not using any of its operands.
2471 class OperandsHider : public TypePromotionAction {
2472 /// The list of original operands.
2473 SmallVector<Value *, 4> OriginalValues;
2474
2475 public:
2476 /// Remove \p Inst from the uses of the operands of \p Inst.
2477 OperandsHider(Instruction *Inst) : TypePromotionAction(Inst) {
2478 LLVM_DEBUG(dbgs() << "Do: OperandsHider: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: OperandsHider: " <<
*Inst << "\n"; } } while (false)
;
2479 unsigned NumOpnds = Inst->getNumOperands();
2480 OriginalValues.reserve(NumOpnds);
2481 for (unsigned It = 0; It < NumOpnds; ++It) {
2482 // Save the current operand.
2483 Value *Val = Inst->getOperand(It);
2484 OriginalValues.push_back(Val);
2485 // Set a dummy one.
2486 // We could use OperandSetter here, but that would imply an overhead
2487 // that we are not willing to pay.
2488 Inst->setOperand(It, UndefValue::get(Val->getType()));
2489 }
2490 }
2491
2492 /// Restore the original list of uses.
2493 void undo() override {
2494 LLVM_DEBUG(dbgs() << "Undo: OperandsHider: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: OperandsHider: "
<< *Inst << "\n"; } } while (false)
;
2495 for (unsigned It = 0, EndIt = OriginalValues.size(); It != EndIt; ++It)
2496 Inst->setOperand(It, OriginalValues[It]);
2497 }
2498 };
2499
2500 /// Build a truncate instruction.
2501 class TruncBuilder : public TypePromotionAction {
2502 Value *Val;
2503
2504 public:
2505 /// Build a truncate instruction of \p Opnd producing a \p Ty
2506 /// result.
2507 /// trunc Opnd to Ty.
2508 TruncBuilder(Instruction *Opnd, Type *Ty) : TypePromotionAction(Opnd) {
2509 IRBuilder<> Builder(Opnd);
2510 Val = Builder.CreateTrunc(Opnd, Ty, "promoted");
2511 LLVM_DEBUG(dbgs() << "Do: TruncBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: TruncBuilder: " <<
*Val << "\n"; } } while (false)
;
2512 }
2513
2514 /// Get the built value.
2515 Value *getBuiltValue() { return Val; }
2516
2517 /// Remove the built instruction.
2518 void undo() override {
2519 LLVM_DEBUG(dbgs() << "Undo: TruncBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: TruncBuilder: " <<
*Val << "\n"; } } while (false)
;
2520 if (Instruction *IVal = dyn_cast<Instruction>(Val))
2521 IVal->eraseFromParent();
2522 }
2523 };
2524
2525 /// Build a sign extension instruction.
2526 class SExtBuilder : public TypePromotionAction {
2527 Value *Val;
2528
2529 public:
2530 /// Build a sign extension instruction of \p Opnd producing a \p Ty
2531 /// result.
2532 /// sext Opnd to Ty.
2533 SExtBuilder(Instruction *InsertPt, Value *Opnd, Type *Ty)
2534 : TypePromotionAction(InsertPt) {
2535 IRBuilder<> Builder(InsertPt);
2536 Val = Builder.CreateSExt(Opnd, Ty, "promoted");
2537 LLVM_DEBUG(dbgs() << "Do: SExtBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: SExtBuilder: " <<
*Val << "\n"; } } while (false)
;
2538 }
2539
2540 /// Get the built value.
2541 Value *getBuiltValue() { return Val; }
2542
2543 /// Remove the built instruction.
2544 void undo() override {
2545 LLVM_DEBUG(dbgs() << "Undo: SExtBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: SExtBuilder: " <<
*Val << "\n"; } } while (false)
;
2546 if (Instruction *IVal = dyn_cast<Instruction>(Val))
2547 IVal->eraseFromParent();
2548 }
2549 };
2550
2551 /// Build a zero extension instruction.
2552 class ZExtBuilder : public TypePromotionAction {
2553 Value *Val;
2554
2555 public:
2556 /// Build a zero extension instruction of \p Opnd producing a \p Ty
2557 /// result.
2558 /// zext Opnd to Ty.
2559 ZExtBuilder(Instruction *InsertPt, Value *Opnd, Type *Ty)
2560 : TypePromotionAction(InsertPt) {
2561 IRBuilder<> Builder(InsertPt);
2562 Val = Builder.CreateZExt(Opnd, Ty, "promoted");
2563 LLVM_DEBUG(dbgs() << "Do: ZExtBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: ZExtBuilder: " <<
*Val << "\n"; } } while (false)
;
2564 }
2565
2566 /// Get the built value.
2567 Value *getBuiltValue() { return Val; }
2568
2569 /// Remove the built instruction.
2570 void undo() override {
2571 LLVM_DEBUG(dbgs() << "Undo: ZExtBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: ZExtBuilder: " <<
*Val << "\n"; } } while (false)
;
2572 if (Instruction *IVal = dyn_cast<Instruction>(Val))
2573 IVal->eraseFromParent();
2574 }
2575 };
2576
2577 /// Mutate an instruction to another type.
2578 class TypeMutator : public TypePromotionAction {
2579 /// Record the original type.
2580 Type *OrigTy;
2581
2582 public:
2583 /// Mutate the type of \p Inst into \p NewTy.
2584 TypeMutator(Instruction *Inst, Type *NewTy)
2585 : TypePromotionAction(Inst), OrigTy(Inst->getType()) {
2586 LLVM_DEBUG(dbgs() << "Do: MutateType: " << *Inst << " with " << *NewTydo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: MutateType: " <<
*Inst << " with " << *NewTy << "\n"; } } while
(false)
2587 << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: MutateType: " <<
*Inst << " with " << *NewTy << "\n"; } } while
(false)
;
2588 Inst->mutateType(NewTy);
2589 }
2590
2591 /// Mutate the instruction back to its original type.
2592 void undo() override {
2593 LLVM_DEBUG(dbgs() << "Undo: MutateType: " << *Inst << " with " << *OrigTydo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: MutateType: " <<
*Inst << " with " << *OrigTy << "\n"; } } while
(false)
2594 << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: MutateType: " <<
*Inst << " with " << *OrigTy << "\n"; } } while
(false)
;
2595 Inst->mutateType(OrigTy);
2596 }
2597 };
2598
2599 /// Replace the uses of an instruction by another instruction.
2600 class UsesReplacer : public TypePromotionAction {
2601 /// Helper structure to keep track of the replaced uses.
2602 struct InstructionAndIdx {
2603 /// The instruction using the instruction.
2604 Instruction *Inst;
2605
2606 /// The index where this instruction is used for Inst.
2607 unsigned Idx;
2608
2609 InstructionAndIdx(Instruction *Inst, unsigned Idx)
2610 : Inst(Inst), Idx(Idx) {}
2611 };
2612
2613 /// Keep track of the original uses (pair Instruction, Index).
2614 SmallVector<InstructionAndIdx, 4> OriginalUses;
2615 /// Keep track of the debug users.
2616 SmallVector<DbgValueInst *, 1> DbgValues;
2617
2618 using use_iterator = SmallVectorImpl<InstructionAndIdx>::iterator;
2619
2620 public:
2621 /// Replace all the use of \p Inst by \p New.
2622 UsesReplacer(Instruction *Inst, Value *New) : TypePromotionAction(Inst) {
2623 LLVM_DEBUG(dbgs() << "Do: UsersReplacer: " << *Inst << " with " << *Newdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: UsersReplacer: " <<
*Inst << " with " << *New << "\n"; } } while
(false)
2624 << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: UsersReplacer: " <<
*Inst << " with " << *New << "\n"; } } while
(false)
;
2625 // Record the original uses.
2626 for (Use &U : Inst->uses()) {
2627 Instruction *UserI = cast<Instruction>(U.getUser());
2628 OriginalUses.push_back(InstructionAndIdx(UserI, U.getOperandNo()));
2629 }
2630 // Record the debug uses separately. They are not in the instruction's
2631 // use list, but they are replaced by RAUW.
2632 findDbgValues(DbgValues, Inst);
2633
2634 // Now, we can replace the uses.
2635 Inst->replaceAllUsesWith(New);
2636 }
2637
2638 /// Reassign the original uses of Inst to Inst.
2639 void undo() override {
2640 LLVM_DEBUG(dbgs() << "Undo: UsersReplacer: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: UsersReplacer: "
<< *Inst << "\n"; } } while (false)
;
2641 for (use_iterator UseIt = OriginalUses.begin(),
2642 EndIt = OriginalUses.end();
2643 UseIt != EndIt; ++UseIt) {
2644 UseIt->Inst->setOperand(UseIt->Idx, Inst);
2645 }
2646 // RAUW has replaced all original uses with references to the new value,
2647 // including the debug uses. Since we are undoing the replacements,
2648 // the original debug uses must also be reinstated to maintain the
2649 // correctness and utility of debug value instructions.
2650 for (auto *DVI: DbgValues) {
2651 LLVMContext &Ctx = Inst->getType()->getContext();
2652 auto *MV = MetadataAsValue::get(Ctx, ValueAsMetadata::get(Inst));
2653 DVI->setOperand(0, MV);
2654 }
2655 }
2656 };
2657
2658 /// Remove an instruction from the IR.
2659 class InstructionRemover : public TypePromotionAction {
2660 /// Original position of the instruction.
2661 InsertionHandler Inserter;
2662
2663 /// Helper structure to hide all the link to the instruction. In other
2664 /// words, this helps to do as if the instruction was removed.
2665 OperandsHider Hider;
2666
2667 /// Keep track of the uses replaced, if any.
2668 UsesReplacer *Replacer = nullptr;
2669
2670 /// Keep track of instructions removed.
2671 SetOfInstrs &RemovedInsts;
2672
2673 public:
2674 /// Remove all reference of \p Inst and optionally replace all its
2675 /// uses with New.
2676 /// \p RemovedInsts Keep track of the instructions removed by this Action.
2677 /// \pre If !Inst->use_empty(), then New != nullptr
2678 InstructionRemover(Instruction *Inst, SetOfInstrs &RemovedInsts,
2679 Value *New = nullptr)
2680 : TypePromotionAction(Inst), Inserter(Inst), Hider(Inst),
2681 RemovedInsts(RemovedInsts) {
2682 if (New)
2683 Replacer = new UsesReplacer(Inst, New);
2684 LLVM_DEBUG(dbgs() << "Do: InstructionRemover: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: InstructionRemover: "
<< *Inst << "\n"; } } while (false)
;
2685 RemovedInsts.insert(Inst);
2686 /// The instructions removed here will be freed after completing
2687 /// optimizeBlock() for all blocks as we need to keep track of the
2688 /// removed instructions during promotion.
2689 Inst->removeFromParent();
2690 }
2691
2692 ~InstructionRemover() override { delete Replacer; }
2693
2694 /// Resurrect the instruction and reassign it to the proper uses if
2695 /// new value was provided when build this action.
2696 void undo() override {
2697 LLVM_DEBUG(dbgs() << "Undo: InstructionRemover: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: InstructionRemover: "
<< *Inst << "\n"; } } while (false)
;
2698 Inserter.insert(Inst);
2699 if (Replacer)
2700 Replacer->undo();
2701 Hider.undo();
2702 RemovedInsts.erase(Inst);
2703 }
2704 };
2705
2706public:
2707 /// Restoration point.
2708 /// The restoration point is a pointer to an action instead of an iterator
2709 /// because the iterator may be invalidated but not the pointer.
2710 using ConstRestorationPt = const TypePromotionAction *;
2711
2712 TypePromotionTransaction(SetOfInstrs &RemovedInsts)
2713 : RemovedInsts(RemovedInsts) {}
2714
2715 /// Advocate every changes made in that transaction.
2716 void commit();
2717
2718 /// Undo all the changes made after the given point.
2719 void rollback(ConstRestorationPt Point);
2720
2721 /// Get the current restoration point.
2722 ConstRestorationPt getRestorationPoint() const;
2723
2724 /// \name API for IR modification with state keeping to support rollback.
2725 /// @{
2726 /// Same as Instruction::setOperand.
2727 void setOperand(Instruction *Inst, unsigned Idx, Value *NewVal);
2728
2729 /// Same as Instruction::eraseFromParent.
2730 void eraseInstruction(Instruction *Inst, Value *NewVal = nullptr);
2731
2732 /// Same as Value::replaceAllUsesWith.
2733 void replaceAllUsesWith(Instruction *Inst, Value *New);
2734
2735 /// Same as Value::mutateType.
2736 void mutateType(Instruction *Inst, Type *NewTy);
2737
2738 /// Same as IRBuilder::createTrunc.
2739 Value *createTrunc(Instruction *Opnd, Type *Ty);
2740
2741 /// Same as IRBuilder::createSExt.
2742 Value *createSExt(Instruction *Inst, Value *Opnd, Type *Ty);
2743
2744 /// Same as IRBuilder::createZExt.
2745 Value *createZExt(Instruction *Inst, Value *Opnd, Type *Ty);
2746
2747 /// Same as Instruction::moveBefore.
2748 void moveBefore(Instruction *Inst, Instruction *Before);
2749 /// @}
2750
2751private:
2752 /// The ordered list of actions made so far.
2753 SmallVector<std::unique_ptr<TypePromotionAction>, 16> Actions;
2754
2755 using CommitPt = SmallVectorImpl<std::unique_ptr<TypePromotionAction>>::iterator;
2756
2757 SetOfInstrs &RemovedInsts;
2758};
2759
2760} // end anonymous namespace
2761
2762void TypePromotionTransaction::setOperand(Instruction *Inst, unsigned Idx,
2763 Value *NewVal) {
2764 Actions.push_back(std::make_unique<TypePromotionTransaction::OperandSetter>(
2765 Inst, Idx, NewVal));
2766}
2767
2768void TypePromotionTransaction::eraseInstruction(Instruction *Inst,
2769 Value *NewVal) {
2770 Actions.push_back(
2771 std::make_unique<TypePromotionTransaction::InstructionRemover>(
2772 Inst, RemovedInsts, NewVal));
2773}
2774
2775void TypePromotionTransaction::replaceAllUsesWith(Instruction *Inst,
2776 Value *New) {
2777 Actions.push_back(
2778 std::make_unique<TypePromotionTransaction::UsesReplacer>(Inst, New));
2779}
2780
2781void TypePromotionTransaction::mutateType(Instruction *Inst, Type *NewTy) {
2782 Actions.push_back(
2783 std::make_unique<TypePromotionTransaction::TypeMutator>(Inst, NewTy));
2784}
2785
2786Value *TypePromotionTransaction::createTrunc(Instruction *Opnd,
2787 Type *Ty) {
2788 std::unique_ptr<TruncBuilder> Ptr(new TruncBuilder(Opnd, Ty));
2789 Value *Val = Ptr->getBuiltValue();
2790 Actions.push_back(std::move(Ptr));
2791 return Val;
2792}
2793
2794Value *TypePromotionTransaction::createSExt(Instruction *Inst,
2795 Value *Opnd, Type *Ty) {
2796 std::unique_ptr<SExtBuilder> Ptr(new SExtBuilder(Inst, Opnd, Ty));
2797 Value *Val = Ptr->getBuiltValue();
2798 Actions.push_back(std::move(Ptr));
2799 return Val;
2800}
2801
2802Value *TypePromotionTransaction::createZExt(Instruction *Inst,
2803 Value *Opnd, Type *Ty) {
2804 std::unique_ptr<ZExtBuilder> Ptr(new ZExtBuilder(Inst, Opnd, Ty));
2805 Value *Val = Ptr->getBuiltValue();
2806 Actions.push_back(std::move(Ptr));
2807 return Val;
2808}
2809
2810void TypePromotionTransaction::moveBefore(Instruction *Inst,
2811 Instruction *Before) {
2812 Actions.push_back(
2813 std::make_unique<TypePromotionTransaction::InstructionMoveBefore>(
2814 Inst, Before));
2815}
2816
2817TypePromotionTransaction::ConstRestorationPt
2818TypePromotionTransaction::getRestorationPoint() const {
2819 return !Actions.empty() ? Actions.back().get() : nullptr;
2820}
2821
2822void TypePromotionTransaction::commit() {
2823 for (CommitPt It = Actions.begin(), EndIt = Actions.end(); It != EndIt;
2824 ++It)
2825 (*It)->commit();
2826 Actions.clear();
2827}
2828
2829void TypePromotionTransaction::rollback(
2830 TypePromotionTransaction::ConstRestorationPt Point) {
2831 while (!Actions.empty() && Point != Actions.back().get()) {
2832 std::unique_ptr<TypePromotionAction> Curr = Actions.pop_back_val();
2833 Curr->undo();
2834 }
2835}
2836
2837namespace {
2838
2839/// A helper class for matching addressing modes.
2840///
2841/// This encapsulates the logic for matching the target-legal addressing modes.
2842class AddressingModeMatcher {
2843 SmallVectorImpl<Instruction*> &AddrModeInsts;
2844 const TargetLowering &TLI;
2845 const TargetRegisterInfo &TRI;
2846 const DataLayout &DL;
2847
2848 /// AccessTy/MemoryInst - This is the type for the access (e.g. double) and
2849 /// the memory instruction that we're computing this address for.
2850 Type *AccessTy;
2851 unsigned AddrSpace;
2852 Instruction *MemoryInst;
2853
2854 /// This is the addressing mode that we're building up. This is
2855 /// part of the return value of this addressing mode matching stuff.
2856 ExtAddrMode &AddrMode;
2857
2858 /// The instructions inserted by other CodeGenPrepare optimizations.
2859 const SetOfInstrs &InsertedInsts;
2860
2861 /// A map from the instructions to their type before promotion.
2862 InstrToOrigTy &PromotedInsts;
2863
2864 /// The ongoing transaction where every action should be registered.
2865 TypePromotionTransaction &TPT;
2866
2867 // A GEP which has too large offset to be folded into the addressing mode.
2868 std::pair<AssertingVH<GetElementPtrInst>, int64_t> &LargeOffsetGEP;
2869
2870 /// This is set to true when we should not do profitability checks.
2871 /// When true, IsProfitableToFoldIntoAddressingMode always returns true.
2872 bool IgnoreProfitability;
2873
2874 AddressingModeMatcher(
2875 SmallVectorImpl<Instruction *> &AMI, const TargetLowering &TLI,
2876 const TargetRegisterInfo &TRI, Type *AT, unsigned AS, Instruction *MI,
2877 ExtAddrMode &AM, const SetOfInstrs &InsertedInsts,
2878 InstrToOrigTy &PromotedInsts, TypePromotionTransaction &TPT,
2879 std::pair<AssertingVH<GetElementPtrInst>, int64_t> &LargeOffsetGEP)
2880 : AddrModeInsts(AMI), TLI(TLI), TRI(TRI),
2881 DL(MI->getModule()->getDataLayout()), AccessTy(AT), AddrSpace(AS),
2882 MemoryInst(MI), AddrMode(AM), InsertedInsts(InsertedInsts),
2883 PromotedInsts(PromotedInsts), TPT(TPT), LargeOffsetGEP(LargeOffsetGEP) {
2884 IgnoreProfitability = false;
2885 }
2886
2887public:
2888 /// Find the maximal addressing mode that a load/store of V can fold,
2889 /// give an access type of AccessTy. This returns a list of involved
2890 /// instructions in AddrModeInsts.
2891 /// \p InsertedInsts The instructions inserted by other CodeGenPrepare
2892 /// optimizations.
2893 /// \p PromotedInsts maps the instructions to their type before promotion.
2894 /// \p The ongoing transaction where every action should be registered.
2895 static ExtAddrMode
2896 Match(Value *V, Type *AccessTy, unsigned AS, Instruction *MemoryInst,
2897 SmallVectorImpl<Instruction *> &AddrModeInsts,
2898 const TargetLowering &TLI, const TargetRegisterInfo &TRI,
2899 const SetOfInstrs &InsertedInsts, InstrToOrigTy &PromotedInsts,
2900 TypePromotionTransaction &TPT,
2901 std::pair<AssertingVH<GetElementPtrInst>, int64_t> &LargeOffsetGEP) {
2902 ExtAddrMode Result;
2903
2904 bool Success = AddressingModeMatcher(AddrModeInsts, TLI, TRI, AccessTy, AS,
2905 MemoryInst, Result, InsertedInsts,
2906 PromotedInsts, TPT, LargeOffsetGEP)
2907 .matchAddr(V, 0);
2908 (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-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 2908, __PRETTY_FUNCTION__))
;
2909 return Result;
2910 }
2911
2912private:
2913 bool matchScaledValue(Value *ScaleReg, int64_t Scale, unsigned Depth);
2914 bool matchAddr(Value *Addr, unsigned Depth);
2915 bool matchOperationAddr(User *AddrInst, unsigned Opcode, unsigned Depth,
2916 bool *MovedAway = nullptr);
2917 bool isProfitableToFoldIntoAddressingMode(Instruction *I,
2918 ExtAddrMode &AMBefore,
2919 ExtAddrMode &AMAfter);
2920 bool valueAlreadyLiveAtInst(Value *Val, Value *KnownLive1, Value *KnownLive2);
2921 bool isPromotionProfitable(unsigned NewCost, unsigned OldCost,
2922 Value *PromotedOperand) const;
2923};
2924
2925class PhiNodeSet;
2926
2927/// An iterator for PhiNodeSet.
2928class PhiNodeSetIterator {
2929 PhiNodeSet * const Set;
2930 size_t CurrentIndex = 0;
2931
2932public:
2933 /// The constructor. Start should point to either a valid element, or be equal
2934 /// to the size of the underlying SmallVector of the PhiNodeSet.
2935 PhiNodeSetIterator(PhiNodeSet * const Set, size_t Start);
2936 PHINode * operator*() const;
2937 PhiNodeSetIterator& operator++();
2938 bool operator==(const PhiNodeSetIterator &RHS) const;
2939 bool operator!=(const PhiNodeSetIterator &RHS) const;
2940};
2941
2942/// Keeps a set of PHINodes.
2943///
2944/// This is a minimal set implementation for a specific use case:
2945/// It is very fast when there are very few elements, but also provides good
2946/// performance when there are many. It is similar to SmallPtrSet, but also
2947/// provides iteration by insertion order, which is deterministic and stable
2948/// across runs. It is also similar to SmallSetVector, but provides removing
2949/// elements in O(1) time. This is achieved by not actually removing the element
2950/// from the underlying vector, so comes at the cost of using more memory, but
2951/// that is fine, since PhiNodeSets are used as short lived objects.
2952class PhiNodeSet {
2953 friend class PhiNodeSetIterator;
2954
2955 using MapType = SmallDenseMap<PHINode *, size_t, 32>;
2956 using iterator = PhiNodeSetIterator;
2957
2958 /// Keeps the elements in the order of their insertion in the underlying
2959 /// vector. To achieve constant time removal, it never deletes any element.
2960 SmallVector<PHINode *, 32> NodeList;
2961
2962 /// Keeps the elements in the underlying set implementation. This (and not the
2963 /// NodeList defined above) is the source of truth on whether an element
2964 /// is actually in the collection.
2965 MapType NodeMap;
2966
2967 /// Points to the first valid (not deleted) element when the set is not empty
2968 /// and the value is not zero. Equals to the size of the underlying vector
2969 /// when the set is empty. When the value is 0, as in the beginning, the
2970 /// first element may or may not be valid.
2971 size_t FirstValidElement = 0;
2972
2973public:
2974 /// Inserts a new element to the collection.
2975 /// \returns true if the element is actually added, i.e. was not in the
2976 /// collection before the operation.
2977 bool insert(PHINode *Ptr) {
2978 if (NodeMap.insert(std::make_pair(Ptr, NodeList.size())).second) {
2979 NodeList.push_back(Ptr);
2980 return true;
2981 }
2982 return false;
2983 }
2984
2985 /// Removes the element from the collection.
2986 /// \returns whether the element is actually removed, i.e. was in the
2987 /// collection before the operation.
2988 bool erase(PHINode *Ptr) {
2989 auto it = NodeMap.find(Ptr);
2990 if (it != NodeMap.end()) {
2991 NodeMap.erase(Ptr);
2992 SkipRemovedElements(FirstValidElement);
2993 return true;
2994 }
2995 return false;
2996 }
2997
2998 /// Removes all elements and clears the collection.
2999 void clear() {
3000 NodeMap.clear();
3001 NodeList.clear();
3002 FirstValidElement = 0;
3003 }
3004
3005 /// \returns an iterator that will iterate the elements in the order of
3006 /// insertion.
3007 iterator begin() {
3008 if (FirstValidElement == 0)
3009 SkipRemovedElements(FirstValidElement);
3010 return PhiNodeSetIterator(this, FirstValidElement);
3011 }
3012
3013 /// \returns an iterator that points to the end of the collection.
3014 iterator end() { return PhiNodeSetIterator(this, NodeList.size()); }
3015
3016 /// Returns the number of elements in the collection.
3017 size_t size() const {
3018 return NodeMap.size();
3019 }
3020
3021 /// \returns 1 if the given element is in the collection, and 0 if otherwise.
3022 size_t count(PHINode *Ptr) const {
3023 return NodeMap.count(Ptr);
3024 }
3025
3026private:
3027 /// Updates the CurrentIndex so that it will point to a valid element.
3028 ///
3029 /// If the element of NodeList at CurrentIndex is valid, it does not
3030 /// change it. If there are no more valid elements, it updates CurrentIndex
3031 /// to point to the end of the NodeList.
3032 void SkipRemovedElements(size_t &CurrentIndex) {
3033 while (CurrentIndex < NodeList.size()) {
3034 auto it = NodeMap.find(NodeList[CurrentIndex]);
3035 // If the element has been deleted and added again later, NodeMap will
3036 // point to a different index, so CurrentIndex will still be invalid.
3037 if (it != NodeMap.end() && it->second == CurrentIndex)
3038 break;
3039 ++CurrentIndex;
3040 }
3041 }
3042};
3043
3044PhiNodeSetIterator::PhiNodeSetIterator(PhiNodeSet *const Set, size_t Start)
3045 : Set(Set), CurrentIndex(Start) {}
3046
3047PHINode * PhiNodeSetIterator::operator*() const {
3048 assert(CurrentIndex < Set->NodeList.size() &&((CurrentIndex < Set->NodeList.size() && "PhiNodeSet access out of range"
) ? static_cast<void> (0) : __assert_fail ("CurrentIndex < Set->NodeList.size() && \"PhiNodeSet access out of range\""
, "/build/llvm-toolchain-snapshot-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 3049, __PRETTY_FUNCTION__))
3049 "PhiNodeSet access out of range")((CurrentIndex < Set->NodeList.size() && "PhiNodeSet access out of range"
) ? static_cast<void> (0) : __assert_fail ("CurrentIndex < Set->NodeList.size() && \"PhiNodeSet access out of range\""
, "/build/llvm-toolchain-snapshot-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 3049, __PRETTY_FUNCTION__))
;
3050 return Set->NodeList[CurrentIndex];
3051}
3052
3053PhiNodeSetIterator& PhiNodeSetIterator::operator++() {
3054 assert(CurrentIndex < Set->NodeList.size() &&((CurrentIndex < Set->NodeList.size() && "PhiNodeSet access out of range"
) ? static_cast<void> (0) : __assert_fail ("CurrentIndex < Set->NodeList.size() && \"PhiNodeSet access out of range\""
, "/build/llvm-toolchain-snapshot-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 3055, __PRETTY_FUNCTION__))
3055 "PhiNodeSet access out of range")((CurrentIndex < Set->NodeList.size() && "PhiNodeSet access out of range"
) ? static_cast<void> (0) : __assert_fail ("CurrentIndex < Set->NodeList.size() && \"PhiNodeSet access out of range\""
, "/build/llvm-toolchain-snapshot-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 3055, __PRETTY_FUNCTION__))
;
3056 ++CurrentIndex;
3057 Set->SkipRemovedElements(CurrentIndex);
3058 return *this;
3059}
3060
3061bool PhiNodeSetIterator::operator==(const PhiNodeSetIterator &RHS) const {
3062 return CurrentIndex == RHS.CurrentIndex;
3063}
3064
3065bool PhiNodeSetIterator::operator!=(const PhiNodeSetIterator &RHS) const {
3066 return !((*this) == RHS);
3067}
3068
3069/// Keep track of simplification of Phi nodes.
3070/// Accept the set of all phi nodes and erase phi node from this set
3071/// if it is simplified.
3072class SimplificationTracker {
3073 DenseMap<Value *, Value *> Storage;
3074 const SimplifyQuery &SQ;
3075 // Tracks newly created Phi nodes. The elements are iterated by insertion
3076 // order.
3077 PhiNodeSet AllPhiNodes;
3078 // Tracks newly created Select nodes.
3079 SmallPtrSet<SelectInst *, 32> AllSelectNodes;
3080
3081public:
3082 SimplificationTracker(const SimplifyQuery &sq)
3083 : SQ(sq) {}
3084
3085 Value *Get(Value *V) {
3086 do {
3087 auto SV = Storage.find(V);
3088 if (SV == Storage.end())
3089 return V;
3090 V = SV->second;
3091 } while (true);
3092 }
3093
3094 Value *Simplify(Value *Val) {
3095 SmallVector<Value *, 32> WorkList;
3096 SmallPtrSet<Value *, 32> Visited;
3097 WorkList.push_back(Val);
3098 while (!WorkList.empty()) {
3099 auto P = WorkList.pop_back_val();
3100 if (!Visited.insert(P).second)
3101 continue;
3102 if (auto *PI = dyn_cast<Instruction>(P))
3103 if (Value *V = SimplifyInstruction(cast<Instruction>(PI), SQ)) {
3104 for (auto *U : PI->users())
3105 WorkList.push_back(cast<Value>(U));
3106 Put(PI, V);
3107 PI->replaceAllUsesWith(V);
3108 if (auto *PHI = dyn_cast<PHINode>(PI))
3109 AllPhiNodes.erase(PHI);
3110 if (auto *Select = dyn_cast<SelectInst>(PI))
3111 AllSelectNodes.erase(Select);
3112 PI->eraseFromParent();
3113 }
3114 }
3115 return Get(Val);
3116 }
3117
3118 void Put(Value *From, Value *To) {
3119 Storage.insert({ From, To });
3120 }
3121
3122 void ReplacePhi(PHINode *From, PHINode *To) {
3123 Value* OldReplacement = Get(From);
3124 while (OldReplacement != From) {
3125 From = To;
3126 To = dyn_cast<PHINode>(OldReplacement);
3127 OldReplacement = Get(From);
3128 }
3129 assert(To && Get(To) == To && "Replacement PHI node is already replaced.")((To && Get(To) == To && "Replacement PHI node is already replaced."
) ? static_cast<void> (0) : __assert_fail ("To && Get(To) == To && \"Replacement PHI node is already replaced.\""
, "/build/llvm-toolchain-snapshot-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 3129, __PRETTY_FUNCTION__))
;
3130 Put(From, To);
3131 From->replaceAllUsesWith(To);
3132 AllPhiNodes.erase(From);
3133 From->eraseFromParent();
3134 }
3135
3136 PhiNodeSet& newPhiNodes() { return AllPhiNodes; }
3137
3138 void insertNewPhi(PHINode *PN) { AllPhiNodes.insert(PN); }
3139
3140 void insertNewSelect(SelectInst *SI) { AllSelectNodes.insert(SI); }
3141
3142 unsigned countNewPhiNodes() const { return AllPhiNodes.size(); }
3143
3144 unsigned countNewSelectNodes() const { return AllSelectNodes.size(); }
3145
3146 void destroyNewNodes(Type *CommonType) {
3147 // For safe erasing, replace the uses with dummy value first.
3148 auto Dummy = UndefValue::get(CommonType);
3149 for (auto I : AllPhiNodes) {
3150 I->replaceAllUsesWith(Dummy);
3151 I->eraseFromParent();
3152 }
3153 AllPhiNodes.clear();
3154 for (auto I : AllSelectNodes) {
3155 I->replaceAllUsesWith(Dummy);
3156 I->eraseFromParent();
3157 }
3158 AllSelectNodes.clear();
3159 }
3160};
3161
3162/// A helper class for combining addressing modes.
3163class AddressingModeCombiner {
3164 typedef DenseMap<Value *, Value *> FoldAddrToValueMapping;
3165 typedef std::pair<PHINode *, PHINode *> PHIPair;
3166
3167private:
3168 /// The addressing modes we've collected.
3169 SmallVector<ExtAddrMode, 16> AddrModes;
3170
3171 /// The field in which the AddrModes differ, when we have more than one.
3172 ExtAddrMode::FieldName DifferentField = ExtAddrMode::NoField;
3173
3174 /// Are the AddrModes that we have all just equal to their original values?
3175 bool AllAddrModesTrivial = true;
3176
3177 /// Common Type for all different fields in addressing modes.
3178 Type *CommonType;
3179
3180 /// SimplifyQuery for simplifyInstruction utility.
3181 const SimplifyQuery &SQ;
3182
3183 /// Original Address.
3184 Value *Original;
3185
3186public:
3187 AddressingModeCombiner(const SimplifyQuery &_SQ, Value *OriginalValue)
3188 : CommonType(nullptr), SQ(_SQ), Original(OriginalValue) {}
3189
3190 /// Get the combined AddrMode
3191 const ExtAddrMode &getAddrMode() const {
3192 return AddrModes[0];
3193 }
3194
3195 /// Add a new AddrMode if it's compatible with the AddrModes we already
3196 /// have.
3197 /// \return True iff we succeeded in doing so.
3198 bool addNewAddrMode(ExtAddrMode &NewAddrMode) {
3199 // Take note of if we have any non-trivial AddrModes, as we need to detect
3200 // when all AddrModes are trivial as then we would introduce a phi or select
3201 // which just duplicates what's already there.
3202 AllAddrModesTrivial = AllAddrModesTrivial && NewAddrMode.isTrivial();
3203
3204 // If this is the first addrmode then everything is fine.
3205 if (AddrModes.empty()) {
3206 AddrModes.emplace_back(NewAddrMode);
3207 return true;
3208 }
3209
3210 // Figure out how different this is from the other address modes, which we
3211 // can do just by comparing against the first one given that we only care
3212 // about the cumulative difference.
3213 ExtAddrMode::FieldName ThisDifferentField =
3214 AddrModes[0].compare(NewAddrMode);
3215 if (DifferentField == ExtAddrMode::NoField)
3216 DifferentField = ThisDifferentField;
3217 else if (DifferentField != ThisDifferentField)
3218 DifferentField = ExtAddrMode::MultipleFields;
3219
3220 // If NewAddrMode differs in more than one dimension we cannot handle it.
3221 bool CanHandle = DifferentField != ExtAddrMode::MultipleFields;
3222
3223 // If Scale Field is different then we reject.
3224 CanHandle = CanHandle && DifferentField != ExtAddrMode::ScaleField;
3225
3226 // We also must reject the case when base offset is different and
3227 // scale reg is not null, we cannot handle this case due to merge of
3228 // different offsets will be used as ScaleReg.
3229 CanHandle = CanHandle && (DifferentField != ExtAddrMode::BaseOffsField ||
3230 !NewAddrMode.ScaledReg);
3231
3232 // We also must reject the case when GV is different and BaseReg installed
3233 // due to we want to use base reg as a merge of GV values.
3234 CanHandle = CanHandle && (DifferentField != ExtAddrMode::BaseGVField ||
3235 !NewAddrMode.HasBaseReg);
3236
3237 // Even if NewAddMode is the same we still need to collect it due to
3238 // original value is different. And later we will need all original values
3239 // as anchors during finding the common Phi node.
3240 if (CanHandle)
3241 AddrModes.emplace_back(NewAddrMode);
3242 else
3243 AddrModes.clear();
3244
3245 return CanHandle;
3246 }
3247
3248 /// Combine the addressing modes we've collected into a single
3249 /// addressing mode.
3250 /// \return True iff we successfully combined them or we only had one so
3251 /// didn't need to combine them anyway.
3252 bool combineAddrModes() {
3253 // If we have no AddrModes then they can't be combined.
3254 if (AddrModes.size() == 0)
3255 return false;
3256
3257 // A single AddrMode can trivially be combined.
3258 if (AddrModes.size() == 1 || DifferentField == ExtAddrMode::NoField)
3259 return true;
3260
3261 // If the AddrModes we collected are all just equal to the value they are
3262 // derived from then combining them wouldn't do anything useful.
3263 if (AllAddrModesTrivial)
3264 return false;
3265
3266 if (!addrModeCombiningAllowed())
3267 return false;
3268
3269 // Build a map between <original value, basic block where we saw it> to
3270 // value of base register.
3271 // Bail out if there is no common type.
3272 FoldAddrToValueMapping Map;
3273 if (!initializeMap(Map))
3274 return false;
3275
3276 Value *CommonValue = findCommon(Map);
3277 if (CommonValue)
3278 AddrModes[0].SetCombinedField(DifferentField, CommonValue, AddrModes);
3279 return CommonValue != nullptr;
3280 }
3281
3282private:
3283 /// Initialize Map with anchor values. For address seen
3284 /// we set the value of different field saw in this address.
3285 /// At the same time we find a common type for different field we will
3286 /// use to create new Phi/Select nodes. Keep it in CommonType field.
3287 /// Return false if there is no common type found.
3288 bool initializeMap(FoldAddrToValueMapping &Map) {
3289 // Keep track of keys where the value is null. We will need to replace it
3290 // with constant null when we know the common type.
3291 SmallVector<Value *, 2> NullValue;
3292 Type *IntPtrTy = SQ.DL.getIntPtrType(AddrModes[0].OriginalValue->getType());
3293 for (auto &AM : AddrModes) {
3294 Value *DV = AM.GetFieldAsValue(DifferentField, IntPtrTy);
3295 if (DV) {
3296 auto *Type = DV->getType();
3297 if (CommonType && CommonType != Type)
3298 return false;
3299 CommonType = Type;
3300 Map[AM.OriginalValue] = DV;
3301 } else {
3302 NullValue.push_back(AM.OriginalValue);
3303 }
3304 }
3305 assert(CommonType && "At least one non-null value must be!")((CommonType && "At least one non-null value must be!"
) ? static_cast<void> (0) : __assert_fail ("CommonType && \"At least one non-null value must be!\""
, "/build/llvm-toolchain-snapshot-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 3305, __PRETTY_FUNCTION__))
;
3306 for (auto *V : NullValue)
3307 Map[V] = Constant::getNullValue(CommonType);
3308 return true;
3309 }
3310
3311 /// We have mapping between value A and other value B where B was a field in
3312 /// addressing mode represented by A. Also we have an original value C
3313 /// representing an address we start with. Traversing from C through phi and
3314 /// selects we ended up with A's in a map. This utility function tries to find
3315 /// a value V which is a field in addressing mode C and traversing through phi
3316 /// nodes and selects we will end up in corresponded values B in a map.
3317 /// The utility will create a new Phi/Selects if needed.
3318 // The simple example looks as follows:
3319 // BB1:
3320 // p1 = b1 + 40
3321 // br cond BB2, BB3
3322 // BB2:
3323 // p2 = b2 + 40
3324 // br BB3
3325 // BB3:
3326 // p = phi [p1, BB1], [p2, BB2]
3327 // v = load p
3328 // Map is
3329 // p1 -> b1
3330 // p2 -> b2
3331 // Request is
3332 // p -> ?
3333 // The function tries to find or build phi [b1, BB1], [b2, BB2] in BB3.
3334 Value *findCommon(FoldAddrToValueMapping &Map) {
3335 // Tracks the simplification of newly created phi nodes. The reason we use
3336 // this mapping is because we will add new created Phi nodes in AddrToBase.
3337 // Simplification of Phi nodes is recursive, so some Phi node may
3338 // be simplified after we added it to AddrToBase. In reality this
3339 // simplification is possible only if original phi/selects were not
3340 // simplified yet.
3341 // Using this mapping we can find the current value in AddrToBase.
3342 SimplificationTracker ST(SQ);
3343
3344 // First step, DFS to create PHI nodes for all intermediate blocks.
3345 // Also fill traverse order for the second step.
3346 SmallVector<Value *, 32> TraverseOrder;
3347 InsertPlaceholders(Map, TraverseOrder, ST);
3348
3349 // Second Step, fill new nodes by merged values and simplify if possible.
3350 FillPlaceholders(Map, TraverseOrder, ST);
3351
3352 if (!AddrSinkNewSelects && ST.countNewSelectNodes() > 0) {
3353 ST.destroyNewNodes(CommonType);
3354 return nullptr;
3355 }
3356
3357 // Now we'd like to match New Phi nodes to existed ones.
3358 unsigned PhiNotMatchedCount = 0;
3359 if (!MatchPhiSet(ST, AddrSinkNewPhis, PhiNotMatchedCount)) {
3360 ST.destroyNewNodes(CommonType);
3361 return nullptr;
3362 }
3363
3364 auto *Result = ST.Get(Map.find(Original)->second);
3365 if (Result) {
3366 NumMemoryInstsPhiCreated += ST.countNewPhiNodes() + PhiNotMatchedCount;
3367 NumMemoryInstsSelectCreated += ST.countNewSelectNodes();
3368 }
3369 return Result;
3370 }
3371
3372 /// Try to match PHI node to Candidate.
3373 /// Matcher tracks the matched Phi nodes.
3374 bool MatchPhiNode(PHINode *PHI, PHINode *Candidate,
3375 SmallSetVector<PHIPair, 8> &Matcher,
3376 PhiNodeSet &PhiNodesToMatch) {
3377 SmallVector<PHIPair, 8> WorkList;
3378 Matcher.insert({ PHI, Candidate });
3379 SmallSet<PHINode *, 8> MatchedPHIs;
3380 MatchedPHIs.insert(PHI);
3381 WorkList.push_back({ PHI, Candidate });
3382 SmallSet<PHIPair, 8> Visited;
3383 while (!WorkList.empty()) {
3384 auto Item = WorkList.pop_back_val();
3385 if (!Visited.insert(Item).second)
3386 continue;
3387 // We iterate over all incoming values to Phi to compare them.
3388 // If values are different and both of them Phi and the first one is a
3389 // Phi we added (subject to match) and both of them is in the same basic
3390 // block then we can match our pair if values match. So we state that
3391 // these values match and add it to work list to verify that.
3392 for (auto B : Item.first->blocks()) {
3393 Value *FirstValue = Item.first->getIncomingValueForBlock(B);
3394 Value *SecondValue = Item.second->getIncomingValueForBlock(B);
3395 if (FirstValue == SecondValue)
3396 continue;
3397
3398 PHINode *FirstPhi = dyn_cast<PHINode>(FirstValue);
3399 PHINode *SecondPhi = dyn_cast<PHINode>(SecondValue);
3400
3401 // One of them is not Phi or
3402 // The first one is not Phi node from the set we'd like to match or
3403 // Phi nodes from different basic blocks then
3404 // we will not be able to match.
3405 if (!FirstPhi || !SecondPhi || !PhiNodesToMatch.count(FirstPhi) ||
3406 FirstPhi->getParent() != SecondPhi->getParent())
3407 return false;
3408
3409 // If we already matched them then continue.
3410 if (Matcher.count({ FirstPhi, SecondPhi }))
3411 continue;
3412 // So the values are different and does not match. So we need them to
3413 // match. (But we register no more than one match per PHI node, so that
3414 // we won't later try to replace them twice.)
3415 if (MatchedPHIs.insert(FirstPhi).second)
3416 Matcher.insert({ FirstPhi, SecondPhi });
3417 // But me must check it.
3418 WorkList.push_back({ FirstPhi, SecondPhi });
3419 }
3420 }
3421 return true;
3422 }
3423
3424 /// For the given set of PHI nodes (in the SimplificationTracker) try
3425 /// to find their equivalents.
3426 /// Returns false if this matching fails and creation of new Phi is disabled.
3427 bool MatchPhiSet(SimplificationTracker &ST, bool AllowNewPhiNodes,
3428 unsigned &PhiNotMatchedCount) {
3429 // Matched and PhiNodesToMatch iterate their elements in a deterministic
3430 // order, so the replacements (ReplacePhi) are also done in a deterministic
3431 // order.
3432 SmallSetVector<PHIPair, 8> Matched;
3433 SmallPtrSet<PHINode *, 8> WillNotMatch;
3434 PhiNodeSet &PhiNodesToMatch = ST.newPhiNodes();
3435 while (PhiNodesToMatch.size()) {
3436 PHINode *PHI = *PhiNodesToMatch.begin();
3437
3438 // Add us, if no Phi nodes in the basic block we do not match.
3439 WillNotMatch.clear();
3440 WillNotMatch.insert(PHI);
3441
3442 // Traverse all Phis until we found equivalent or fail to do that.
3443 bool IsMatched = false;
3444 for (auto &P : PHI->getParent()->phis()) {
3445 if (&P == PHI)
3446 continue;
3447 if ((IsMatched = MatchPhiNode(PHI, &P, Matched, PhiNodesToMatch)))
3448 break;
3449 // If it does not match, collect all Phi nodes from matcher.
3450 // if we end up with no match, them all these Phi nodes will not match
3451 // later.
3452 for (auto M : Matched)
3453 WillNotMatch.insert(M.first);
3454 Matched.clear();
3455 }
3456 if (IsMatched) {
3457 // Replace all matched values and erase them.
3458 for (auto MV : Matched)
3459 ST.ReplacePhi(MV.first, MV.second);
3460 Matched.clear();
3461 continue;
3462 }
3463 // If we are not allowed to create new nodes then bail out.
3464 if (!AllowNewPhiNodes)
3465 return false;
3466 // Just remove all seen values in matcher. They will not match anything.
3467 PhiNotMatchedCount += WillNotMatch.size();
3468 for (auto *P : WillNotMatch)
3469 PhiNodesToMatch.erase(P);
3470 }
3471 return true;
3472 }
3473 /// Fill the placeholders with values from predecessors and simplify them.
3474 void FillPlaceholders(FoldAddrToValueMapping &Map,
3475 SmallVectorImpl<Value *> &TraverseOrder,
3476 SimplificationTracker &ST) {
3477 while (!TraverseOrder.empty()) {
3478 Value *Current = TraverseOrder.pop_back_val();
3479 assert(Map.find(Current) != Map.end() && "No node to fill!!!")((Map.find(Current) != Map.end() && "No node to fill!!!"
) ? static_cast<void> (0) : __assert_fail ("Map.find(Current) != Map.end() && \"No node to fill!!!\""
, "/build/llvm-toolchain-snapshot-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 3479, __PRETTY_FUNCTION__))
;
3480 Value *V = Map[Current];
3481
3482 if (SelectInst *Select = dyn_cast<SelectInst>(V)) {
3483 // CurrentValue also must be Select.
3484 auto *CurrentSelect = cast<SelectInst>(Current);
3485 auto *TrueValue = CurrentSelect->getTrueValue();
3486 assert(Map.find(TrueValue) != Map.end() && "No True Value!")((Map.find(TrueValue) != Map.end() && "No True Value!"
) ? static_cast<void> (0) : __assert_fail ("Map.find(TrueValue) != Map.end() && \"No True Value!\""
, "/build/llvm-toolchain-snapshot-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 3486, __PRETTY_FUNCTION__))
;
3487 Select->setTrueValue(ST.Get(Map[TrueValue]));
3488 auto *FalseValue = CurrentSelect->getFalseValue();
3489 assert(Map.find(FalseValue) != Map.end() && "No False Value!")((Map.find(FalseValue) != Map.end() && "No False Value!"
) ? static_cast<void> (0) : __assert_fail ("Map.find(FalseValue) != Map.end() && \"No False Value!\""
, "/build/llvm-toolchain-snapshot-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 3489, __PRETTY_FUNCTION__))
;
3490 Select->setFalseValue(ST.Get(Map[FalseValue]));
3491 } else {
3492 // Must be a Phi node then.
3493 auto *PHI = cast<PHINode>(V);
3494 // Fill the Phi node with values from predecessors.
3495 for (auto B : predecessors(PHI->getParent())) {
3496 Value *PV = cast<PHINode>(Current)->getIncomingValueForBlock(B);
3497 assert(Map.find(PV) != Map.end() && "No predecessor Value!")((Map.find(PV) != Map.end() && "No predecessor Value!"
) ? static_cast<void> (0) : __assert_fail ("Map.find(PV) != Map.end() && \"No predecessor Value!\""
, "/build/llvm-toolchain-snapshot-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 3497, __PRETTY_FUNCTION__))
;
3498 PHI->addIncoming(ST.Get(Map[PV]), B);
3499 }
3500 }
3501 Map[Current] = ST.Simplify(V);
3502 }
3503 }
3504
3505 /// Starting from original value recursively iterates over def-use chain up to
3506 /// known ending values represented in a map. For each traversed phi/select
3507 /// inserts a placeholder Phi or Select.
3508 /// Reports all new created Phi/Select nodes by adding them to set.
3509 /// Also reports and order in what values have been traversed.
3510 void InsertPlaceholders(FoldAddrToValueMapping &Map,
3511 SmallVectorImpl<Value *> &TraverseOrder,
3512 SimplificationTracker &ST) {
3513 SmallVector<Value *, 32> Worklist;
3514 assert((isa<PHINode>(Original) || isa<SelectInst>(Original)) &&(((isa<PHINode>(Original) || isa<SelectInst>(Original
)) && "Address must be a Phi or Select node") ? static_cast
<void> (0) : __assert_fail ("(isa<PHINode>(Original) || isa<SelectInst>(Original)) && \"Address must be a Phi or Select node\""
, "/build/llvm-toolchain-snapshot-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 3515, __PRETTY_FUNCTION__))
3515 "Address must be a Phi or Select node")(((isa<PHINode>(Original) || isa<SelectInst>(Original
)) && "Address must be a Phi or Select node") ? static_cast
<void> (0) : __assert_fail ("(isa<PHINode>(Original) || isa<SelectInst>(Original)) && \"Address must be a Phi or Select node\""
, "/build/llvm-toolchain-snapshot-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 3515, __PRETTY_FUNCTION__))
;
3516 auto *Dummy = UndefValue::get(CommonType);
3517 Worklist.push_back(Original);
3518 while (!Worklist.empty()) {
3519 Value *Current = Worklist.pop_back_val();
3520 // if it is already visited or it is an ending value then skip it.
3521 if (Map.find(Current) != Map.end())
3522 continue;
3523 TraverseOrder.push_back(Current);
3524
3525 // CurrentValue must be a Phi node or select. All others must be covered
3526 // by anchors.
3527 if (SelectInst *CurrentSelect = dyn_cast<SelectInst>(Current)) {
3528 // Is it OK to get metadata from OrigSelect?!
3529 // Create a Select placeholder with dummy value.
3530 SelectInst *Select = SelectInst::Create(
3531 CurrentSelect->getCondition(), Dummy, Dummy,
3532 CurrentSelect->getName(), CurrentSelect, CurrentSelect);
3533 Map[Current] = Select;
3534 ST.insertNewSelect(Select);
3535 // We are interested in True and False values.
3536 Worklist.push_back(CurrentSelect->getTrueValue());
3537 Worklist.push_back(CurrentSelect->getFalseValue());
3538 } else {
3539 // It must be a Phi node then.
3540 PHINode *CurrentPhi = cast<PHINode>(Current);
3541 unsigned PredCount = CurrentPhi->getNumIncomingValues();
3542 PHINode *PHI =
3543 PHINode::Create(CommonType, PredCount, "sunk_phi", CurrentPhi);
3544 Map[Current] = PHI;
3545 ST.insertNewPhi(PHI);
3546 for (Value *P : CurrentPhi->incoming_values())
3547 Worklist.push_back(P);
3548 }
3549 }
3550 }
3551
3552 bool addrModeCombiningAllowed() {
3553 if (DisableComplexAddrModes)
3554 return false;
3555 switch (DifferentField) {
3556 default:
3557 return false;
3558 case ExtAddrMode::BaseRegField:
3559 return AddrSinkCombineBaseReg;
3560 case ExtAddrMode::BaseGVField:
3561 return AddrSinkCombineBaseGV;
3562 case ExtAddrMode::BaseOffsField:
3563 return AddrSinkCombineBaseOffs;
3564 case ExtAddrMode::ScaledRegField:
3565 return AddrSinkCombineScaledReg;
3566 }
3567 }
3568};
3569} // end anonymous namespace
3570
3571/// Try adding ScaleReg*Scale to the current addressing mode.
3572/// Return true and update AddrMode if this addr mode is legal for the target,
3573/// false if not.
3574bool AddressingModeMatcher::matchScaledValue(Value *ScaleReg, int64_t Scale,
3575 unsigned Depth) {
3576 // If Scale is 1, then this is the same as adding ScaleReg to the addressing
3577 // mode. Just process that directly.
3578 if (Scale == 1)
3579 return matchAddr(ScaleReg, Depth);
3580
3581 // If the scale is 0, it takes nothing to add this.
3582 if (Scale == 0)
3583 return true;
3584
3585 // If we already have a scale of this value, we can add to it, otherwise, we
3586 // need an available scale field.
3587 if (AddrMode.Scale != 0 && AddrMode.ScaledReg != ScaleReg)
3588 return false;
3589
3590 ExtAddrMode TestAddrMode = AddrMode;
3591
3592 // Add scale to turn X*4+X*3 -> X*7. This could also do things like
3593 // [A+B + A*7] -> [B+A*8].
3594 TestAddrMode.Scale += Scale;
3595 TestAddrMode.ScaledReg = ScaleReg;
3596
3597 // If the new address isn't legal, bail out.
3598 if (!TLI.isLegalAddressingMode(DL, TestAddrMode, AccessTy, AddrSpace))
3599 return false;
3600
3601 // It was legal, so commit it.
3602 AddrMode = TestAddrMode;
3603
3604 // Okay, we decided that we can add ScaleReg+Scale to AddrMode. Check now
3605 // to see if ScaleReg is actually X+C. If so, we can turn this into adding
3606 // X*Scale + C*Scale to addr mode.
3607 ConstantInt *CI = nullptr; Value *AddLHS = nullptr;
3608 if (isa<Instruction>(ScaleReg) && // not a constant expr.
3609 match(ScaleReg, m_Add(m_Value(AddLHS), m_ConstantInt(CI)))) {
3610 TestAddrMode.InBounds = false;
3611 TestAddrMode.ScaledReg = AddLHS;
3612 TestAddrMode.BaseOffs += CI->getSExtValue()*TestAddrMode.Scale;
3613
3614 // If this addressing mode is legal, commit it and remember that we folded
3615 // this instruction.
3616 if (TLI.isLegalAddressingMode(DL, TestAddrMode, AccessTy, AddrSpace)) {
3617 AddrModeInsts.push_back(cast<Instruction>(ScaleReg));
3618 AddrMode = TestAddrMode;
3619 return true;
3620 }
3621 }
3622
3623 // Otherwise, not (x+c)*scale, just return what we have.
3624 return true;
3625}
3626
3627/// This is a little filter, which returns true if an addressing computation
3628/// involving I might be folded into a load/store accessing it.
3629/// This doesn't need to be perfect, but needs to accept at least
3630/// the set of instructions that MatchOperationAddr can.
3631static bool MightBeFoldableInst(Instruction *I) {
3632 switch (I->getOpcode()) {
3633 case Instruction::BitCast:
3634 case Instruction::AddrSpaceCast:
3635 // Don't touch identity bitcasts.
3636 if (I->getType() == I->getOperand(0)->getType())
3637 return false;
3638 return I->getType()->isIntOrPtrTy();
3639 case Instruction::PtrToInt:
3640 // PtrToInt is always a noop, as we know that the int type is pointer sized.
3641 return true;
3642 case Instruction::IntToPtr:
3643 // We know the input is intptr_t, so this is foldable.
3644 return true;
3645 case Instruction::Add:
3646 return true;
3647 case Instruction::Mul:
3648 case Instruction::Shl:
3649 // Can only handle X*C and X << C.
3650 return isa<ConstantInt>(I->getOperand(1));
3651 case Instruction::GetElementPtr:
3652 return true;
3653 default:
3654 return false;
3655 }
3656}
3657
3658/// Check whether or not \p Val is a legal instruction for \p TLI.
3659/// \note \p Val is assumed to be the product of some type promotion.
3660/// Therefore if \p Val has an undefined state in \p TLI, this is assumed
3661/// to be legal, as the non-promoted value would have had the same state.
3662static bool isPromotedInstructionLegal(const TargetLowering &TLI,
3663 const DataLayout &DL, Value *Val) {
3664 Instruction *PromotedInst = dyn_cast<Instruction>(Val);
3665 if (!PromotedInst)
3666 return false;
3667 int ISDOpcode = TLI.InstructionOpcodeToISD(PromotedInst->getOpcode());
3668 // If the ISDOpcode is undefined, it was undefined before the promotion.
3669 if (!ISDOpcode)
3670 return true;
3671 // Otherwise, check if the promoted instruction is legal or not.
3672 return TLI.isOperationLegalOrCustom(
3673 ISDOpcode, TLI.getValueType(DL, PromotedInst->getType()));
3674}
3675
3676namespace {
3677
3678/// Hepler class to perform type promotion.
3679class TypePromotionHelper {
3680 /// Utility function to add a promoted instruction \p ExtOpnd to
3681 /// \p PromotedInsts and record the type of extension we have seen.
3682 static void addPromotedInst(InstrToOrigTy &PromotedInsts,
3683 Instruction *ExtOpnd,
3684 bool IsSExt) {
3685 ExtType ExtTy = IsSExt ? SignExtension : ZeroExtension;
3686 InstrToOrigTy::iterator It = PromotedInsts.find(ExtOpnd);
3687 if (It != PromotedInsts.end()) {
3688 // If the new extension is same as original, the information in
3689 // PromotedInsts[ExtOpnd] is still correct.
3690 if (It->second.getInt() == ExtTy)
3691 return;
3692
3693 // Now the new extension is different from old extension, we make
3694 // the type information invalid by setting extension type to
3695 // BothExtension.
3696 ExtTy = BothExtension;
3697 }
3698 PromotedInsts[ExtOpnd] = TypeIsSExt(ExtOpnd->getType(), ExtTy);
3699 }
3700
3701 /// Utility function to query the original type of instruction \p Opnd
3702 /// with a matched extension type. If the extension doesn't match, we
3703 /// cannot use the information we had on the original type.
3704 /// BothExtension doesn't match any extension type.
3705 static const Type *getOrigType(const InstrToOrigTy &PromotedInsts,
3706 Instruction *Opnd,
3707 bool IsSExt) {
3708 ExtType ExtTy = IsSExt ? SignExtension : ZeroExtension;
3709 InstrToOrigTy::const_iterator It = PromotedInsts.find(Opnd);
3710 if (It != PromotedInsts.end() && It->second.getInt() == ExtTy)
3711 return It->second.getPointer();
3712 return nullptr;
3713 }
3714
3715 /// Utility function to check whether or not a sign or zero extension
3716 /// of \p Inst with \p ConsideredExtType can be moved through \p Inst by
3717 /// either using the operands of \p Inst or promoting \p Inst.
3718 /// The type of the extension is defined by \p IsSExt.
3719 /// In other words, check if:
3720 /// ext (Ty Inst opnd1 opnd2 ... opndN) to ConsideredExtType.
3721 /// #1 Promotion applies:
3722 /// ConsideredExtType Inst (ext opnd1 to ConsideredExtType, ...).
3723 /// #2 Operand reuses:
3724 /// ext opnd1 to ConsideredExtType.
3725 /// \p PromotedInsts maps the instructions to their type before promotion.
3726 static bool canGetThrough(const Instruction *Inst, Type *ConsideredExtType,
3727 const InstrToOrigTy &PromotedInsts, bool IsSExt);
3728
3729 /// Utility function to determine if \p OpIdx should be promoted when
3730 /// promoting \p Inst.
3731 static bool shouldExtOperand(const Instruction *Inst, int OpIdx) {
3732 return !(isa<SelectInst>(Inst) && OpIdx == 0);
3733 }
3734
3735 /// Utility function to promote the operand of \p Ext when this
3736 /// operand is a promotable trunc or sext or zext.
3737 /// \p PromotedInsts maps the instructions to their type before promotion.
3738 /// \p CreatedInstsCost[out] contains the cost of all instructions
3739 /// created to promote the operand of Ext.
3740 /// Newly added extensions are inserted in \p Exts.
3741 /// Newly added truncates are inserted in \p Truncs.
3742 /// Should never be called directly.
3743 /// \return The promoted value which is used instead of Ext.
3744 static Value *promoteOperandForTruncAndAnyExt(
3745 Instruction *Ext, TypePromotionTransaction &TPT,
3746 InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
3747 SmallVectorImpl<Instruction *> *Exts,
3748 SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI);
3749
3750 /// Utility function to promote the operand of \p Ext when this
3751 /// operand is promotable and is not a supported trunc or sext.
3752 /// \p PromotedInsts maps the instructions to their type before promotion.
3753 /// \p CreatedInstsCost[out] contains the cost of all the instructions
3754 /// created to promote the operand of Ext.
3755 /// Newly added extensions are inserted in \p Exts.
3756 /// Newly added truncates are inserted in \p Truncs.
3757 /// Should never be called directly.
3758 /// \return The promoted value which is used instead of Ext.
3759 static Value *promoteOperandForOther(Instruction *Ext,
3760 TypePromotionTransaction &TPT,
3761 InstrToOrigTy &PromotedInsts,
3762 unsigned &CreatedInstsCost,
3763 SmallVectorImpl<Instruction *> *Exts,
3764 SmallVectorImpl<Instruction *> *Truncs,
3765 const TargetLowering &TLI, bool IsSExt);
3766
3767 /// \see promoteOperandForOther.
3768 static Value *signExtendOperandForOther(
3769 Instruction *Ext, TypePromotionTransaction &TPT,
3770 InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
3771 SmallVectorImpl<Instruction *> *Exts,
3772 SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI) {
3773 return promoteOperandForOther(Ext, TPT, PromotedInsts, CreatedInstsCost,
3774 Exts, Truncs, TLI, true);
3775 }
3776
3777 /// \see promoteOperandForOther.
3778 static Value *zeroExtendOperandForOther(
3779 Instruction *Ext, TypePromotionTransaction &TPT,
3780 InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
3781 SmallVectorImpl<Instruction *> *Exts,
3782 SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI) {
3783 return promoteOperandForOther(Ext, TPT, PromotedInsts, CreatedInstsCost,
3784 Exts, Truncs, TLI, false);
3785 }
3786
3787public:
3788 /// Type for the utility function that promotes the operand of Ext.
3789 using Action = Value *(*)(Instruction *Ext, TypePromotionTransaction &TPT,
3790 InstrToOrigTy &PromotedInsts,
3791 unsigned &CreatedInstsCost,
3792 SmallVectorImpl<Instruction *> *Exts,
3793 SmallVectorImpl<Instruction *> *Truncs,
3794 const TargetLowering &TLI);
3795
3796 /// Given a sign/zero extend instruction \p Ext, return the appropriate
3797 /// action to promote the operand of \p Ext instead of using Ext.
3798 /// \return NULL if no promotable action is possible with the current
3799 /// sign extension.
3800 /// \p InsertedInsts keeps track of all the instructions inserted by the
3801 /// other CodeGenPrepare optimizations. This information is important
3802 /// because we do not want to promote these instructions as CodeGenPrepare
3803 /// will reinsert them later. Thus creating an infinite loop: create/remove.
3804 /// \p PromotedInsts maps the instructions to their type before promotion.
3805 static Action getAction(Instruction *Ext, const SetOfInstrs &InsertedInsts,
3806 const TargetLowering &TLI,
3807 const InstrToOrigTy &PromotedInsts);
3808};
3809
3810} // end anonymous namespace
3811
3812bool TypePromotionHelper::canGetThrough(const Instruction *Inst,
3813 Type *ConsideredExtType,
3814 const InstrToOrigTy &PromotedInsts,
3815 bool IsSExt) {
3816 // The promotion helper does not know how to deal with vector types yet.
3817 // To be able to fix that, we would need to fix the places where we
3818 // statically extend, e.g., constants and such.
3819 if (Inst->getType()->isVectorTy())
3820 return false;
3821
3822 // We can always get through zext.
3823 if (isa<ZExtInst>(Inst))
3824 return true;
3825
3826 // sext(sext) is ok too.
3827 if (IsSExt && isa<SExtInst>(Inst))
3828 return true;
3829
3830 // We can get through binary operator, if it is legal. In other words, the
3831 // binary operator must have a nuw or nsw flag.
3832 const BinaryOperator *BinOp = dyn_cast<BinaryOperator>(Inst);
3833 if (BinOp && isa<OverflowingBinaryOperator>(BinOp) &&
3834 ((!IsSExt && BinOp->hasNoUnsignedWrap()) ||
3835 (IsSExt && BinOp->hasNoSignedWrap())))
3836 return true;
3837
3838 // ext(and(opnd, cst)) --> and(ext(opnd), ext(cst))
3839 if ((Inst->getOpcode() == Instruction::And ||
3840 Inst->getOpcode() == Instruction::Or))
3841 return true;
3842
3843 // ext(xor(opnd, cst)) --> xor(ext(opnd), ext(cst))
3844 if (Inst->getOpcode() == Instruction::Xor) {
3845 const ConstantInt *Cst = dyn_cast<ConstantInt>(Inst->getOperand(1));
3846 // Make sure it is not a NOT.
3847 if (Cst && !Cst->getValue().isAllOnesValue())
3848 return true;
3849 }
3850
3851 // zext(shrl(opnd, cst)) --> shrl(zext(opnd), zext(cst))
3852 // It may change a poisoned value into a regular value, like
3853 // zext i32 (shrl i8 %val, 12) --> shrl i32 (zext i8 %val), 12
3854 // poisoned value regular value
3855 // It should be OK since undef covers valid value.
3856 if (Inst->getOpcode() == Instruction::LShr && !IsSExt)
3857 return true;
3858
3859 // and(ext(shl(opnd, cst)), cst) --> and(shl(ext(opnd), ext(cst)), cst)
3860 // It may change a poisoned value into a regular value, like
3861 // zext i32 (shl i8 %val, 12) --> shl i32 (zext i8 %val), 12
3862 // poisoned value regular value
3863 // It should be OK since undef covers valid value.
3864 if (Inst->getOpcode() == Instruction::Shl && Inst->hasOneUse()) {
3865 const auto *ExtInst = cast<const Instruction>(*Inst->user_begin());
3866 if (ExtInst->hasOneUse()) {
3867 const auto *AndInst = dyn_cast<const Instruction>(*ExtInst->user_begin());
3868 if (AndInst && AndInst->getOpcode() == Instruction::And) {
3869 const auto *Cst = dyn_cast<ConstantInt>(AndInst->getOperand(1));
3870 if (Cst &&
3871 Cst->getValue().isIntN(Inst->getType()->getIntegerBitWidth()))
3872 return true;
3873 }
3874 }
3875 }
3876
3877 // Check if we can do the following simplification.
3878 // ext(trunc(opnd)) --> ext(opnd)
3879 if (!isa<TruncInst>(Inst))
3880 return false;
3881
3882 Value *OpndVal = Inst->getOperand(0);
3883 // Check if we can use this operand in the extension.
3884 // If the type is larger than the result type of the extension, we cannot.
3885 if (!OpndVal->getType()->isIntegerTy() ||
3886 OpndVal->getType()->getIntegerBitWidth() >
3887 ConsideredExtType->getIntegerBitWidth())
3888 return false;
3889
3890 // If the operand of the truncate is not an instruction, we will not have
3891 // any information on the dropped bits.
3892 // (Actually we could for constant but it is not worth the extra logic).
3893 Instruction *Opnd = dyn_cast<Instruction>(OpndVal);
3894 if (!Opnd)
3895 return false;
3896
3897 // Check if the source of the type is narrow enough.
3898 // I.e., check that trunc just drops extended bits of the same kind of
3899 // the extension.
3900 // #1 get the type of the operand and check the kind of the extended bits.
3901 const Type *OpndType = getOrigType(PromotedInsts, Opnd, IsSExt);
3902 if (OpndType)
3903 ;
3904 else if ((IsSExt && isa<SExtInst>(Opnd)) || (!IsSExt && isa<ZExtInst>(Opnd)))
3905 OpndType = Opnd->getOperand(0)->getType();
3906 else
3907 return false;
3908
3909 // #2 check that the truncate just drops extended bits.
3910 return Inst->getType()->getIntegerBitWidth() >=
3911 OpndType->getIntegerBitWidth();
3912}
3913
3914TypePromotionHelper::Action TypePromotionHelper::getAction(
3915 Instruction *Ext, const SetOfInstrs &InsertedInsts,
3916 const TargetLowering &TLI, const InstrToOrigTy &PromotedInsts) {
3917 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-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 3918, __PRETTY_FUNCTION__))
3918 "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-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 3918, __PRETTY_FUNCTION__))
;
3919 Instruction *ExtOpnd = dyn_cast<Instruction>(Ext->getOperand(0));
3920 Type *ExtTy = Ext->getType();
3921 bool IsSExt = isa<SExtInst>(Ext);
3922 // If the operand of the extension is not an instruction, we cannot
3923 // get through.
3924 // If it, check we can get through.
3925 if (!ExtOpnd || !canGetThrough(ExtOpnd, ExtTy, PromotedInsts, IsSExt))
3926 return nullptr;
3927
3928 // Do not promote if the operand has been added by codegenprepare.
3929 // Otherwise, it means we are undoing an optimization that is likely to be
3930 // redone, thus causing potential infinite loop.
3931 if (isa<TruncInst>(ExtOpnd) && InsertedInsts.count(ExtOpnd))
3932 return nullptr;
3933
3934 // SExt or Trunc instructions.
3935 // Return the related handler.
3936 if (isa<SExtInst>(ExtOpnd) || isa<TruncInst>(ExtOpnd) ||
3937 isa<ZExtInst>(ExtOpnd))
3938 return promoteOperandForTruncAndAnyExt;
3939
3940 // Regular instruction.
3941 // Abort early if we will have to insert non-free instructions.
3942 if (!ExtOpnd->hasOneUse() && !TLI.isTruncateFree(ExtTy, ExtOpnd->getType()))
3943 return nullptr;
3944 return IsSExt ? signExtendOperandForOther : zeroExtendOperandForOther;
3945}
3946
3947Value *TypePromotionHelper::promoteOperandForTruncAndAnyExt(
3948 Instruction *SExt, TypePromotionTransaction &TPT,
3949 InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
3950 SmallVectorImpl<Instruction *> *Exts,
3951 SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI) {
3952 // By construction, the operand of SExt is an instruction. Otherwise we cannot
3953 // get through it and this method should not be called.
3954 Instruction *SExtOpnd = cast<Instruction>(SExt->getOperand(0));
3955 Value *ExtVal = SExt;
3956 bool HasMergedNonFreeExt = false;
3957 if (isa<ZExtInst>(SExtOpnd)) {
3958 // Replace s|zext(zext(opnd))
3959 // => zext(opnd).
3960 HasMergedNonFreeExt = !TLI.isExtFree(SExtOpnd);
3961 Value *ZExt =
3962 TPT.createZExt(SExt, SExtOpnd->getOperand(0), SExt->getType());
3963 TPT.replaceAllUsesWith(SExt, ZExt);
3964 TPT.eraseInstruction(SExt);
3965 ExtVal = ZExt;
3966 } else {
3967 // Replace z|sext(trunc(opnd)) or sext(sext(opnd))
3968 // => z|sext(opnd).
3969 TPT.setOperand(SExt, 0, SExtOpnd->getOperand(0));
3970 }
3971 CreatedInstsCost = 0;
3972
3973 // Remove dead code.
3974 if (SExtOpnd->use_empty())
3975 TPT.eraseInstruction(SExtOpnd);
3976
3977 // Check if the extension is still needed.
3978 Instruction *ExtInst = dyn_cast<Instruction>(ExtVal);
3979 if (!ExtInst || ExtInst->getType() != ExtInst->getOperand(0)->getType()) {
3980 if (ExtInst) {
3981 if (Exts)
3982 Exts->push_back(ExtInst);
3983 CreatedInstsCost = !TLI.isExtFree(ExtInst) && !HasMergedNonFreeExt;
3984 }
3985 return ExtVal;
3986 }
3987
3988 // At this point we have: ext ty opnd to ty.
3989 // Reassign the uses of ExtInst to the opnd and remove ExtInst.
3990 Value *NextVal = ExtInst->getOperand(0);
3991 TPT.eraseInstruction(ExtInst, NextVal);
3992 return NextVal;
3993}
3994
3995Value *TypePromotionHelper::promoteOperandForOther(
3996 Instruction *Ext, TypePromotionTransaction &TPT,
3997 InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
3998 SmallVectorImpl<Instruction *> *Exts,
3999 SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI,
4000 bool IsSExt) {
4001 // By construction, the operand of Ext is an instruction. Otherwise we cannot
4002 // get through it and this method should not be called.
4003 Instruction *ExtOpnd = cast<Instruction>(Ext->getOperand(0));
4004 CreatedInstsCost = 0;
4005 if (!ExtOpnd->hasOneUse()) {
4006 // ExtOpnd will be promoted.
4007 // All its uses, but Ext, will need to use a truncated value of the
4008 // promoted version.
4009 // Create the truncate now.
4010 Value *Trunc = TPT.createTrunc(Ext, ExtOpnd->getType());
4011 if (Instruction *ITrunc = dyn_cast<Instruction>(Trunc)) {
4012 // Insert it just after the definition.
4013 ITrunc->moveAfter(ExtOpnd);
4014 if (Truncs)
4015 Truncs->push_back(ITrunc);
4016 }
4017
4018 TPT.replaceAllUsesWith(ExtOpnd, Trunc);
4019 // Restore the operand of Ext (which has been replaced by the previous call
4020 // to replaceAllUsesWith) to avoid creating a cycle trunc <-> sext.
4021 TPT.setOperand(Ext, 0, ExtOpnd);
4022 }
4023
4024 // Get through the Instruction:
4025 // 1. Update its type.
4026 // 2. Replace the uses of Ext by Inst.
4027 // 3. Extend each operand that needs to be extended.
4028
4029 // Remember the original type of the instruction before promotion.
4030 // This is useful to know that the high bits are sign extended bits.
4031 addPromotedInst(PromotedInsts, ExtOpnd, IsSExt);
4032 // Step #1.
4033 TPT.mutateType(ExtOpnd, Ext->getType());
4034 // Step #2.
4035 TPT.replaceAllUsesWith(Ext, ExtOpnd);
4036 // Step #3.
4037 Instruction *ExtForOpnd = Ext;
4038
4039 LLVM_DEBUG(dbgs() << "Propagate Ext to operands\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Propagate Ext to operands\n"
; } } while (false)
;
4040 for (int OpIdx = 0, EndOpIdx = ExtOpnd->getNumOperands(); OpIdx != EndOpIdx;
4041 ++OpIdx) {
4042 LLVM_DEBUG(dbgs() << "Operand:\n" << *(ExtOpnd->getOperand(OpIdx)) << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Operand:\n" << *
(ExtOpnd->getOperand(OpIdx)) << '\n'; } } while (false
)
;
4043 if (ExtOpnd->getOperand(OpIdx)->getType() == Ext->getType() ||
4044 !shouldExtOperand(ExtOpnd, OpIdx)) {
4045 LLVM_DEBUG(dbgs() << "No need to propagate\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "No need to propagate\n"
; } } while (false)
;
4046 continue;
4047 }
4048 // Check if we can statically extend the operand.
4049 Value *Opnd = ExtOpnd->getOperand(OpIdx);
4050 if (const ConstantInt *Cst = dyn_cast<ConstantInt>(Opnd)) {
4051 LLVM_DEBUG(dbgs() << "Statically extend\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Statically extend\n"; }
} while (false)
;
4052 unsigned BitWidth = Ext->getType()->getIntegerBitWidth();
4053 APInt CstVal = IsSExt ? Cst->getValue().sext(BitWidth)
4054 : Cst->getValue().zext(BitWidth);
4055 TPT.setOperand(ExtOpnd, OpIdx, ConstantInt::get(Ext->getType(), CstVal));
4056 continue;
4057 }
4058 // UndefValue are typed, so we have to statically sign extend them.
4059 if (isa<UndefValue>(Opnd)) {
4060 LLVM_DEBUG(dbgs() << "Statically extend\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Statically extend\n"; }
} while (false)
;
4061 TPT.setOperand(ExtOpnd, OpIdx, UndefValue::get(Ext->getType()));
4062 continue;
4063 }
4064
4065 // Otherwise we have to explicitly sign extend the operand.
4066 // Check if Ext was reused to extend an operand.
4067 if (!ExtForOpnd) {
4068 // If yes, create a new one.
4069 LLVM_DEBUG(dbgs() << "More operands to ext\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "More operands to ext\n"
; } } while (false)
;
4070 Value *ValForExtOpnd = IsSExt ? TPT.createSExt(Ext, Opnd, Ext->getType())
4071 : TPT.createZExt(Ext, Opnd, Ext->getType());
4072 if (!isa<Instruction>(ValForExtOpnd)) {
4073 TPT.setOperand(ExtOpnd, OpIdx, ValForExtOpnd);
4074 continue;
4075 }
4076 ExtForOpnd = cast<Instruction>(ValForExtOpnd);
4077 }
4078 if (Exts)
4079 Exts->push_back(ExtForOpnd);
4080 TPT.setOperand(ExtForOpnd, 0, Opnd);
4081
4082 // Move the sign extension before the insertion point.
4083 TPT.moveBefore(ExtForOpnd, ExtOpnd);
4084 TPT.setOperand(ExtOpnd, OpIdx, ExtForOpnd);
4085 CreatedInstsCost += !TLI.isExtFree(ExtForOpnd);
4086 // If more sext are required, new instructions will have to be created.
4087 ExtForOpnd = nullptr;
4088 }
4089 if (ExtForOpnd == Ext) {
4090 LLVM_DEBUG(dbgs() << "Extension is useless now\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Extension is useless now\n"
; } } while (false)
;
4091 TPT.eraseInstruction(Ext);
4092 }
4093 return ExtOpnd;
4094}
4095
4096/// Check whether or not promoting an instruction to a wider type is profitable.
4097/// \p NewCost gives the cost of extension instructions created by the
4098/// promotion.
4099/// \p OldCost gives the cost of extension instructions before the promotion
4100/// plus the number of instructions that have been
4101/// matched in the addressing mode the promotion.
4102/// \p PromotedOperand is the value that has been promoted.
4103/// \return True if the promotion is profitable, false otherwise.
4104bool AddressingModeMatcher::isPromotionProfitable(
4105 unsigned NewCost, unsigned OldCost, Value *PromotedOperand) const {
4106 LLVM_DEBUG(dbgs() << "OldCost: " << OldCost << "\tNewCost: " << NewCostdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "OldCost: " << OldCost
<< "\tNewCost: " << NewCost << '\n'; } } while
(false)
4107 << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "OldCost: " << OldCost
<< "\tNewCost: " << NewCost << '\n'; } } while
(false)
;
4108 // The cost of the new extensions is greater than the cost of the
4109 // old extension plus what we folded.
4110 // This is not profitable.
4111 if (NewCost > OldCost)
4112 return false;
4113 if (NewCost < OldCost)
4114 return true;
4115 // The promotion is neutral but it may help folding the sign extension in
4116 // loads for instance.
4117 // Check that we did not create an illegal instruction.
4118 return isPromotedInstructionLegal(TLI, DL, PromotedOperand);
4119}
4120
4121/// Given an instruction or constant expr, see if we can fold the operation
4122/// into the addressing mode. If so, update the addressing mode and return
4123/// true, otherwise return false without modifying AddrMode.
4124/// If \p MovedAway is not NULL, it contains the information of whether or
4125/// not AddrInst has to be folded into the addressing mode on success.
4126/// If \p MovedAway == true, \p AddrInst will not be part of the addressing
4127/// because it has been moved away.
4128/// Thus AddrInst must not be added in the matched instructions.
4129/// This state can happen when AddrInst is a sext, since it may be moved away.
4130/// Therefore, AddrInst may not be valid when MovedAway is true and it must
4131/// not be referenced anymore.
4132bool AddressingModeMatcher::matchOperationAddr(User *AddrInst, unsigned Opcode,
4133 unsigned Depth,
4134 bool *MovedAway) {
4135 // Avoid exponential behavior on extremely deep expression trees.
4136 if (Depth >= 5) return false;
4137
4138 // By default, all matched instructions stay in place.
4139 if (MovedAway)
4140 *MovedAway = false;
4141
4142 switch (Opcode) {
4143 case Instruction::PtrToInt:
4144 // PtrToInt is always a noop, as we know that the int type is pointer sized.
4145 return matchAddr(AddrInst->getOperand(0), Depth);
4146 case Instruction::IntToPtr: {
4147 auto AS = AddrInst->getType()->getPointerAddressSpace();
4148 auto PtrTy = MVT::getIntegerVT(DL.getPointerSizeInBits(AS));
4149 // This inttoptr is a no-op if the integer type is pointer sized.
4150 if (TLI.getValueType(DL, AddrInst->getOperand(0)->getType()) == PtrTy)
4151 return matchAddr(AddrInst->getOperand(0), Depth);
4152 return false;
4153 }
4154 case Instruction::BitCast:
4155 // BitCast is always a noop, and we can handle it as long as it is
4156 // int->int or pointer->pointer (we don't want int<->fp or something).
4157 if (AddrInst->getOperand(0)->getType()->isIntOrPtrTy() &&
4158 // Don't touch identity bitcasts. These were probably put here by LSR,
4159 // and we don't want to mess around with them. Assume it knows what it
4160 // is doing.
4161 AddrInst->getOperand(0)->getType() != AddrInst->getType())
4162 return matchAddr(AddrInst->getOperand(0), Depth);
4163 return false;
4164 case Instruction::AddrSpaceCast: {
4165 unsigned SrcAS
4166 = AddrInst->getOperand(0)->getType()->getPointerAddressSpace();
4167 unsigned DestAS = AddrInst->getType()->getPointerAddressSpace();
4168 if (TLI.isNoopAddrSpaceCast(SrcAS, DestAS))
4169 return matchAddr(AddrInst->getOperand(0), Depth);
4170 return false;
4171 }
4172 case Instruction::Add: {
4173 // Check to see if we can merge in the RHS then the LHS. If so, we win.
4174 ExtAddrMode BackupAddrMode = AddrMode;
4175 unsigned OldSize = AddrModeInsts.size();
4176 // Start a transaction at this point.
4177 // The LHS may match but not the RHS.
4178 // Therefore, we need a higher level restoration point to undo partially
4179 // matched operation.
4180 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
4181 TPT.getRestorationPoint();
4182
4183 AddrMode.InBounds = false;
4184 if (matchAddr(AddrInst->getOperand(1), Depth+1) &&
4185 matchAddr(AddrInst->getOperand(0), Depth+1))
4186 return true;
4187
4188 // Restore the old addr mode info.
4189 AddrMode = BackupAddrMode;
4190 AddrModeInsts.resize(OldSize);
4191 TPT.rollback(LastKnownGood);
4192
4193 // Otherwise this was over-aggressive. Try merging in the LHS then the RHS.
4194 if (matchAddr(AddrInst->getOperand(0), Depth+1) &&
4195 matchAddr(AddrInst->getOperand(1), Depth+1))
4196 return true;
4197
4198 // Otherwise we definitely can't merge the ADD in.
4199 AddrMode = BackupAddrMode;
4200 AddrModeInsts.resize(OldSize);
4201 TPT.rollback(LastKnownGood);
4202 break;
4203 }
4204 //case Instruction::Or:
4205 // TODO: We can handle "Or Val, Imm" iff this OR is equivalent to an ADD.
4206 //break;
4207 case Instruction::Mul:
4208 case Instruction::Shl: {
4209 // Can only handle X*C and X << C.
4210 AddrMode.InBounds = false;
4211 ConstantInt *RHS = dyn_cast<ConstantInt>(AddrInst->getOperand(1));
4212 if (!RHS || RHS->getBitWidth() > 64)
4213 return false;
4214 int64_t Scale = RHS->getSExtValue();
4215 if (Opcode == Instruction::Shl)
4216 Scale = 1LL << Scale;
4217
4218 return matchScaledValue(AddrInst->getOperand(0), Scale, Depth);
4219 }
4220 case Instruction::GetElementPtr: {
4221 // Scan the GEP. We check it if it contains constant offsets and at most
4222 // one variable offset.
4223 int VariableOperand = -1;
4224 unsigned VariableScale = 0;
4225
4226 int64_t ConstantOffset = 0;
4227 gep_type_iterator GTI = gep_type_begin(AddrInst);
4228 for (unsigned i = 1, e = AddrInst->getNumOperands(); i != e; ++i, ++GTI) {
4229 if (StructType *STy = GTI.getStructTypeOrNull()) {
4230 const StructLayout *SL = DL.getStructLayout(STy);
4231 unsigned Idx =
4232 cast<ConstantInt>(AddrInst->getOperand(i))->getZExtValue();
4233 ConstantOffset += SL->getElementOffset(Idx);
4234 } else {
4235 uint64_t TypeSize = DL.getTypeAllocSize(GTI.getIndexedType());
4236 if (ConstantInt *CI = dyn_cast<ConstantInt>(AddrInst->getOperand(i))) {
4237 const APInt &CVal = CI->getValue();
4238 if (CVal.getMinSignedBits() <= 64) {
4239 ConstantOffset += CVal.getSExtValue() * TypeSize;
4240 continue;
4241 }
4242 }
4243 if (TypeSize) { // Scales of zero don't do anything.
4244 // We only allow one variable index at the moment.
4245 if (VariableOperand != -1)
4246 return false;
4247
4248 // Remember the variable index.
4249 VariableOperand = i;
4250 VariableScale = TypeSize;
4251 }
4252 }
4253 }
4254
4255 // A common case is for the GEP to only do a constant offset. In this case,
4256 // just add it to the disp field and check validity.
4257 if (VariableOperand == -1) {
4258 AddrMode.BaseOffs += ConstantOffset;
4259 if (ConstantOffset == 0 ||
4260 TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace)) {
4261 // Check to see if we can fold the base pointer in too.
4262 if (matchAddr(AddrInst->getOperand(0), Depth+1)) {
4263 if (!cast<GEPOperator>(AddrInst)->isInBounds())
4264 AddrMode.InBounds = false;
4265 return true;
4266 }
4267 } else if (EnableGEPOffsetSplit && isa<GetElementPtrInst>(AddrInst) &&
4268 TLI.shouldConsiderGEPOffsetSplit() && Depth == 0 &&
4269 ConstantOffset > 0) {
4270 // Record GEPs with non-zero offsets as candidates for splitting in the
4271 // event that the offset cannot fit into the r+i addressing mode.
4272 // Simple and common case that only one GEP is used in calculating the
4273 // address for the memory access.
4274 Value *Base = AddrInst->getOperand(0);
4275 auto *BaseI = dyn_cast<Instruction>(Base);
4276 auto *GEP = cast<GetElementPtrInst>(AddrInst);
4277 if (isa<Argument>(Base) || isa<GlobalValue>(Base) ||
4278 (BaseI && !isa<CastInst>(BaseI) &&
4279 !isa<GetElementPtrInst>(BaseI))) {
4280 // Make sure the parent block allows inserting non-PHI instructions
4281 // before the terminator.
4282 BasicBlock *Parent =
4283 BaseI ? BaseI->getParent() : &GEP->getFunction()->getEntryBlock();
4284 if (!Parent->getTerminator()->isEHPad())
4285 LargeOffsetGEP = std::make_pair(GEP, ConstantOffset);
4286 }
4287 }
4288 AddrMode.BaseOffs -= ConstantOffset;
4289 return false;
4290 }
4291
4292 // Save the valid addressing mode in case we can't match.
4293 ExtAddrMode BackupAddrMode = AddrMode;
4294 unsigned OldSize = AddrModeInsts.size();
4295
4296 // See if the scale and offset amount is valid for this target.
4297 AddrMode.BaseOffs += ConstantOffset;
4298 if (!cast<GEPOperator>(AddrInst)->isInBounds())
4299 AddrMode.InBounds = false;
4300
4301 // Match the base operand of the GEP.
4302 if (!matchAddr(AddrInst->getOperand(0), Depth+1)) {
4303 // If it couldn't be matched, just stuff the value in a register.
4304 if (AddrMode.HasBaseReg) {
4305 AddrMode = BackupAddrMode;
4306 AddrModeInsts.resize(OldSize);
4307 return false;
4308 }
4309 AddrMode.HasBaseReg = true;
4310 AddrMode.BaseReg = AddrInst->getOperand(0);
4311 }
4312
4313 // Match the remaining variable portion of the GEP.
4314 if (!matchScaledValue(AddrInst->getOperand(VariableOperand), VariableScale,
4315 Depth)) {
4316 // If it couldn't be matched, try stuffing the base into a register
4317 // instead of matching it, and retrying the match of the scale.
4318 AddrMode = BackupAddrMode;
4319 AddrModeInsts.resize(OldSize);
4320 if (AddrMode.HasBaseReg)
4321 return false;
4322 AddrMode.HasBaseReg = true;
4323 AddrMode.BaseReg = AddrInst->getOperand(0);
4324 AddrMode.BaseOffs += ConstantOffset;
4325 if (!matchScaledValue(AddrInst->getOperand(VariableOperand),
4326 VariableScale, Depth)) {
4327 // If even that didn't work, bail.
4328 AddrMode = BackupAddrMode;
4329 AddrModeInsts.resize(OldSize);
4330 return false;
4331 }
4332 }
4333
4334 return true;
4335 }
4336 case Instruction::SExt:
4337 case Instruction::ZExt: {
4338 Instruction *Ext = dyn_cast<Instruction>(AddrInst);
4339 if (!Ext)
4340 return false;
4341
4342 // Try to move this ext out of the way of the addressing mode.
4343 // Ask for a method for doing so.
4344 TypePromotionHelper::Action TPH =
4345 TypePromotionHelper::getAction(Ext, InsertedInsts, TLI, PromotedInsts);
4346 if (!TPH)
4347 return false;
4348
4349 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
4350 TPT.getRestorationPoint();
4351 unsigned CreatedInstsCost = 0;
4352 unsigned ExtCost = !TLI.isExtFree(Ext);
4353 Value *PromotedOperand =
4354 TPH(Ext, TPT, PromotedInsts, CreatedInstsCost, nullptr, nullptr, TLI);
4355 // SExt has been moved away.
4356 // Thus either it will be rematched later in the recursive calls or it is
4357 // gone. Anyway, we must not fold it into the addressing mode at this point.
4358 // E.g.,
4359 // op = add opnd, 1
4360 // idx = ext op
4361 // addr = gep base, idx
4362 // is now:
4363 // promotedOpnd = ext opnd <- no match here
4364 // op = promoted_add promotedOpnd, 1 <- match (later in recursive calls)
4365 // addr = gep base, op <- match
4366 if (MovedAway)
4367 *MovedAway = true;
4368
4369 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-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 4370, __PRETTY_FUNCTION__))
4370 "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-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 4370, __PRETTY_FUNCTION__))
;
4371
4372 ExtAddrMode BackupAddrMode = AddrMode;
4373 unsigned OldSize = AddrModeInsts.size();
4374
4375 if (!matchAddr(PromotedOperand, Depth) ||
4376 // The total of the new cost is equal to the cost of the created
4377 // instructions.
4378 // The total of the old cost is equal to the cost of the extension plus
4379 // what we have saved in the addressing mode.
4380 !isPromotionProfitable(CreatedInstsCost,
4381 ExtCost + (AddrModeInsts.size() - OldSize),
4382 PromotedOperand)) {
4383 AddrMode = BackupAddrMode;
4384 AddrModeInsts.resize(OldSize);
4385 LLVM_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)
;
4386 TPT.rollback(LastKnownGood);
4387 return false;
4388 }
4389 return true;
4390 }
4391 }
4392 return false;
4393}
4394
4395/// If we can, try to add the value of 'Addr' into the current addressing mode.
4396/// If Addr can't be added to AddrMode this returns false and leaves AddrMode
4397/// unmodified. This assumes that Addr is either a pointer type or intptr_t
4398/// for the target.
4399///
4400bool AddressingModeMatcher::matchAddr(Value *Addr, unsigned Depth) {
4401 // Start a transaction at this point that we will rollback if the matching
4402 // fails.
4403 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
4404 TPT.getRestorationPoint();
4405 if (ConstantInt *CI = dyn_cast<ConstantInt>(Addr)) {
4406 // Fold in immediates if legal for the target.
4407 AddrMode.BaseOffs += CI->getSExtValue();
4408 if (TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace))
4409 return true;
4410 AddrMode.BaseOffs -= CI->getSExtValue();
4411 } else if (GlobalValue *GV = dyn_cast<GlobalValue>(Addr)) {
4412 // If this is a global variable, try to fold it into the addressing mode.
4413 if (!AddrMode.BaseGV) {
4414 AddrMode.BaseGV = GV;
4415 if (TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace))
4416 return true;
4417 AddrMode.BaseGV = nullptr;
4418 }
4419 } else if (Instruction *I = dyn_cast<Instruction>(Addr)) {
4420 ExtAddrMode BackupAddrMode = AddrMode;
4421 unsigned OldSize = AddrModeInsts.size();
4422
4423 // Check to see if it is possible to fold this operation.
4424 bool MovedAway = false;
4425 if (matchOperationAddr(I, I->getOpcode(), Depth, &MovedAway)) {
4426 // This instruction may have been moved away. If so, there is nothing
4427 // to check here.
4428 if (MovedAway)
4429 return true;
4430 // Okay, it's possible to fold this. Check to see if it is actually
4431 // *profitable* to do so. We use a simple cost model to avoid increasing
4432 // register pressure too much.
4433 if (I->hasOneUse() ||
4434 isProfitableToFoldIntoAddressingMode(I, BackupAddrMode, AddrMode)) {
4435 AddrModeInsts.push_back(I);
4436 return true;
4437 }
4438
4439 // It isn't profitable to do this, roll back.
4440 //cerr << "NOT FOLDING: " << *I;
4441 AddrMode = BackupAddrMode;
4442 AddrModeInsts.resize(OldSize);
4443 TPT.rollback(LastKnownGood);
4444 }
4445 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Addr)) {
4446 if (matchOperationAddr(CE, CE->getOpcode(), Depth))
4447 return true;
4448 TPT.rollback(LastKnownGood);
4449 } else if (isa<ConstantPointerNull>(Addr)) {
4450 // Null pointer gets folded without affecting the addressing mode.
4451 return true;
4452 }
4453
4454 // Worse case, the target should support [reg] addressing modes. :)
4455 if (!AddrMode.HasBaseReg) {
4456 AddrMode.HasBaseReg = true;
4457 AddrMode.BaseReg = Addr;
4458 // Still check for legality in case the target supports [imm] but not [i+r].
4459 if (TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace))
4460 return true;
4461 AddrMode.HasBaseReg = false;
4462 AddrMode.BaseReg = nullptr;
4463 }
4464
4465 // If the base register is already taken, see if we can do [r+r].
4466 if (AddrMode.Scale == 0) {
4467 AddrMode.Scale = 1;
4468 AddrMode.ScaledReg = Addr;
4469 if (TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace))
4470 return true;
4471 AddrMode.Scale = 0;
4472 AddrMode.ScaledReg = nullptr;
4473 }
4474 // Couldn't match.
4475 TPT.rollback(LastKnownGood);
4476 return false;
4477}
4478
4479/// Check to see if all uses of OpVal by the specified inline asm call are due
4480/// to memory operands. If so, return true, otherwise return false.
4481static bool IsOperandAMemoryOperand(CallInst *CI, InlineAsm *IA, Value *OpVal,
4482 const TargetLowering &TLI,
4483 const TargetRegisterInfo &TRI) {
4484 const Function *F = CI->getFunction();
4485 TargetLowering::AsmOperandInfoVector TargetConstraints =
4486 TLI.ParseConstraints(F->getParent()->getDataLayout(), &TRI,
4487 ImmutableCallSite(CI));
4488
4489 for (unsigned i = 0, e = TargetConstraints.size(); i != e; ++i) {
4490 TargetLowering::AsmOperandInfo &OpInfo = TargetConstraints[i];
4491
4492 // Compute the constraint code and ConstraintType to use.
4493 TLI.ComputeConstraintToUse(OpInfo, SDValue());
4494
4495 // If this asm operand is our Value*, and if it isn't an indirect memory
4496 // operand, we can't fold it!
4497 if (OpInfo.CallOperandVal == OpVal &&
4498 (OpInfo.ConstraintType != TargetLowering::C_Memory ||
4499 !OpInfo.isIndirect))
4500 return false;
4501 }
4502
4503 return true;
4504}
4505
4506// Max number of memory uses to look at before aborting the search to conserve
4507// compile time.
4508static constexpr int MaxMemoryUsesToScan = 20;
4509
4510/// Recursively walk all the uses of I until we find a memory use.
4511/// If we find an obviously non-foldable instruction, return true.
4512/// Add the ultimately found memory instructions to MemoryUses.
4513static bool FindAllMemoryUses(
4514 Instruction *I,
4515 SmallVectorImpl<std::pair<Instruction *, unsigned>> &MemoryUses,
4516 SmallPtrSetImpl<Instruction *> &ConsideredInsts, const TargetLowering &TLI,
4517 const TargetRegisterInfo &TRI, int SeenInsts = 0) {
4518 // If we already considered this instruction, we're done.
4519 if (!ConsideredInsts.insert(I).second)
4520 return false;
4521
4522 // If this is an obviously unfoldable instruction, bail out.
4523 if (!MightBeFoldableInst(I))
4524 return true;
4525
4526 const bool OptSize = I->getFunction()->hasOptSize();
4527
4528 // Loop over all the uses, recursively processing them.
4529 for (Use &U : I->uses()) {
4530 // Conservatively return true if we're seeing a large number or a deep chain
4531 // of users. This avoids excessive compilation times in pathological cases.
4532 if (SeenInsts++ >= MaxMemoryUsesToScan)
4533 return true;
4534
4535 Instruction *UserI = cast<Instruction>(U.getUser());
4536 if (LoadInst *LI = dyn_cast<LoadInst>(UserI)) {
4537 MemoryUses.push_back(std::make_pair(LI, U.getOperandNo()));
4538 continue;
4539 }
4540
4541 if (StoreInst *SI = dyn_cast<StoreInst>(UserI)) {
4542 unsigned opNo = U.getOperandNo();
4543 if (opNo != StoreInst::getPointerOperandIndex())
4544 return true; // Storing addr, not into addr.
4545 MemoryUses.push_back(std::make_pair(SI, opNo));
4546 continue;
4547 }
4548
4549 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(UserI)) {
4550 unsigned opNo = U.getOperandNo();
4551 if (opNo != AtomicRMWInst::getPointerOperandIndex())
4552 return true; // Storing addr, not into addr.
4553 MemoryUses.push_back(std::make_pair(RMW, opNo));
4554 continue;
4555 }
4556
4557 if (AtomicCmpXchgInst *CmpX = dyn_cast<AtomicCmpXchgInst>(UserI)) {
4558 unsigned opNo = U.getOperandNo();
4559 if (opNo != AtomicCmpXchgInst::getPointerOperandIndex())
4560 return true; // Storing addr, not into addr.
4561 MemoryUses.push_back(std::make_pair(CmpX, opNo));
4562 continue;
4563 }
4564
4565 if (CallInst *CI = dyn_cast<CallInst>(UserI)) {
4566 // If this is a cold call, we can sink the addressing calculation into
4567 // the cold path. See optimizeCallInst
4568 if (!OptSize && CI->hasFnAttr(Attribute::Cold))
4569 continue;
4570
4571 InlineAsm *IA = dyn_cast<InlineAsm>(CI->getCalledValue());
4572 if (!IA) return true;
4573
4574 // If this is a memory operand, we're cool, otherwise bail out.
4575 if (!IsOperandAMemoryOperand(CI, IA, I, TLI, TRI))
4576 return true;
4577 continue;
4578 }
4579
4580 if (FindAllMemoryUses(UserI, MemoryUses, ConsideredInsts, TLI, TRI,
4581 SeenInsts))
4582 return true;
4583 }
4584
4585 return false;
4586}
4587
4588/// Return true if Val is already known to be live at the use site that we're
4589/// folding it into. If so, there is no cost to include it in the addressing
4590/// mode. KnownLive1 and KnownLive2 are two values that we know are live at the
4591/// instruction already.
4592bool AddressingModeMatcher::valueAlreadyLiveAtInst(Value *Val,Value *KnownLive1,
4593 Value *KnownLive2) {
4594 // If Val is either of the known-live values, we know it is live!
4595 if (Val == nullptr || Val == KnownLive1 || Val == KnownLive2)
4596 return true;
4597
4598 // All values other than instructions and arguments (e.g. constants) are live.
4599 if (!isa<Instruction>(Val) && !isa<Argument>(Val)) return true;
4600
4601 // If Val is a constant sized alloca in the entry block, it is live, this is
4602 // true because it is just a reference to the stack/frame pointer, which is
4603 // live for the whole function.
4604 if (AllocaInst *AI = dyn_cast<AllocaInst>(Val))
4605 if (AI->isStaticAlloca())
4606 return true;
4607
4608 // Check to see if this value is already used in the memory instruction's
4609 // block. If so, it's already live into the block at the very least, so we
4610 // can reasonably fold it.
4611 return Val->isUsedInBasicBlock(MemoryInst->getParent());
4612}
4613
4614/// It is possible for the addressing mode of the machine to fold the specified
4615/// instruction into a load or store that ultimately uses it.
4616/// However, the specified instruction has multiple uses.
4617/// Given this, it may actually increase register pressure to fold it
4618/// into the load. For example, consider this code:
4619///
4620/// X = ...
4621/// Y = X+1
4622/// use(Y) -> nonload/store
4623/// Z = Y+1
4624/// load Z
4625///
4626/// In this case, Y has multiple uses, and can be folded into the load of Z
4627/// (yielding load [X+2]). However, doing this will cause both "X" and "X+1" to
4628/// be live at the use(Y) line. If we don't fold Y into load Z, we use one
4629/// fewer register. Since Y can't be folded into "use(Y)" we don't increase the
4630/// number of computations either.
4631///
4632/// Note that this (like most of CodeGenPrepare) is just a rough heuristic. If
4633/// X was live across 'load Z' for other reasons, we actually *would* want to
4634/// fold the addressing mode in the Z case. This would make Y die earlier.
4635bool AddressingModeMatcher::
4636isProfitableToFoldIntoAddressingMode(Instruction *I, ExtAddrMode &AMBefore,
4637 ExtAddrMode &AMAfter) {
4638 if (IgnoreProfitability) return true;
4639
4640 // AMBefore is the addressing mode before this instruction was folded into it,
4641 // and AMAfter is the addressing mode after the instruction was folded. Get
4642 // the set of registers referenced by AMAfter and subtract out those
4643 // referenced by AMBefore: this is the set of values which folding in this
4644 // address extends the lifetime of.
4645 //
4646 // Note that there are only two potential values being referenced here,
4647 // BaseReg and ScaleReg (global addresses are always available, as are any
4648 // folded immediates).
4649 Value *BaseReg = AMAfter.BaseReg, *ScaledReg = AMAfter.ScaledReg;
4650
4651 // If the BaseReg or ScaledReg was referenced by the previous addrmode, their
4652 // lifetime wasn't extended by adding this instruction.
4653 if (valueAlreadyLiveAtInst(BaseReg, AMBefore.BaseReg, AMBefore.ScaledReg))
4654 BaseReg = nullptr;
4655 if (valueAlreadyLiveAtInst(ScaledReg, AMBefore.BaseReg, AMBefore.ScaledReg))
4656 ScaledReg = nullptr;
4657
4658 // If folding this instruction (and it's subexprs) didn't extend any live
4659 // ranges, we're ok with it.
4660 if (!BaseReg && !ScaledReg)
4661 return true;
4662
4663 // If all uses of this instruction can have the address mode sunk into them,
4664 // we can remove the addressing mode and effectively trade one live register
4665 // for another (at worst.) In this context, folding an addressing mode into
4666 // the use is just a particularly nice way of sinking it.
4667 SmallVector<std::pair<Instruction*,unsigned>, 16> MemoryUses;
4668 SmallPtrSet<Instruction*, 16> ConsideredInsts;
4669 if (FindAllMemoryUses(I, MemoryUses, ConsideredInsts, TLI, TRI))
4670 return false; // Has a non-memory, non-foldable use!
4671
4672 // Now that we know that all uses of this instruction are part of a chain of
4673 // computation involving only operations that could theoretically be folded
4674 // into a memory use, loop over each of these memory operation uses and see
4675 // if they could *actually* fold the instruction. The assumption is that
4676 // addressing modes are cheap and that duplicating the computation involved
4677 // many times is worthwhile, even on a fastpath. For sinking candidates
4678 // (i.e. cold call sites), this serves as a way to prevent excessive code
4679 // growth since most architectures have some reasonable small and fast way to
4680 // compute an effective address. (i.e LEA on x86)
4681 SmallVector<Instruction*, 32> MatchedAddrModeInsts;
4682 for (unsigned i = 0, e = MemoryUses.size(); i != e; ++i) {
4683 Instruction *User = MemoryUses[i].first;
4684 unsigned OpNo = MemoryUses[i].second;
4685
4686 // Get the access type of this use. If the use isn't a pointer, we don't
4687 // know what it accesses.
4688 Value *Address = User->getOperand(OpNo);
4689 PointerType *AddrTy = dyn_cast<PointerType>(Address->getType());
4690 if (!AddrTy)
4691 return false;
4692 Type *AddressAccessTy = AddrTy->getElementType();
4693 unsigned AS = AddrTy->getAddressSpace();
4694
4695 // Do a match against the root of this address, ignoring profitability. This
4696 // will tell us if the addressing mode for the memory operation will
4697 // *actually* cover the shared instruction.
4698 ExtAddrMode Result;
4699 std::pair<AssertingVH<GetElementPtrInst>, int64_t> LargeOffsetGEP(nullptr,
4700 0);
4701 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
4702 TPT.getRestorationPoint();
4703 AddressingModeMatcher Matcher(
4704 MatchedAddrModeInsts, TLI, TRI, AddressAccessTy, AS, MemoryInst, Result,
4705 InsertedInsts, PromotedInsts, TPT, LargeOffsetGEP);
4706 Matcher.IgnoreProfitability = true;
4707 bool Success = Matcher.matchAddr(Address, 0);
4708 (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-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 4708, __PRETTY_FUNCTION__))
;
4709
4710 // The match was to check the profitability, the changes made are not
4711 // part of the original matcher. Therefore, they should be dropped
4712 // otherwise the original matcher will not present the right state.
4713 TPT.rollback(LastKnownGood);
4714
4715 // If the match didn't cover I, then it won't be shared by it.
4716 if (!is_contained(MatchedAddrModeInsts, I))
4717 return false;
4718
4719 MatchedAddrModeInsts.clear();
4720 }
4721
4722 return true;
4723}
4724
4725/// Return true if the specified values are defined in a
4726/// different basic block than BB.
4727static bool IsNonLocalValue(Value *V, BasicBlock *BB) {
4728 if (Instruction *I = dyn_cast<Instruction>(V))
4729 return I->getParent() != BB;
4730 return false;
4731}
4732
4733/// Sink addressing mode computation immediate before MemoryInst if doing so
4734/// can be done without increasing register pressure. The need for the
4735/// register pressure constraint means this can end up being an all or nothing
4736/// decision for all uses of the same addressing computation.
4737///
4738/// Load and Store Instructions often have addressing modes that can do
4739/// significant amounts of computation. As such, instruction selection will try
4740/// to get the load or store to do as much computation as possible for the
4741/// program. The problem is that isel can only see within a single block. As
4742/// such, we sink as much legal addressing mode work into the block as possible.
4743///
4744/// This method is used to optimize both load/store and inline asms with memory
4745/// operands. It's also used to sink addressing computations feeding into cold
4746/// call sites into their (cold) basic block.
4747///
4748/// The motivation for handling sinking into cold blocks is that doing so can
4749/// both enable other address mode sinking (by satisfying the register pressure
4750/// constraint above), and reduce register pressure globally (by removing the
4751/// addressing mode computation from the fast path entirely.).
4752bool CodeGenPrepare::optimizeMemoryInst(Instruction *MemoryInst, Value *Addr,
4753 Type *AccessTy, unsigned AddrSpace) {
4754 Value *Repl = Addr;
4755
4756 // Try to collapse single-value PHI nodes. This is necessary to undo
4757 // unprofitable PRE transformations.
4758 SmallVector<Value*, 8> worklist;
4759 SmallPtrSet<Value*, 16> Visited;
4760 worklist.push_back(Addr);
4761
4762 // Use a worklist to iteratively look through PHI and select nodes, and
4763 // ensure that the addressing mode obtained from the non-PHI/select roots of
4764 // the graph are compatible.
4765 bool PhiOrSelectSeen = false;
4766 SmallVector<Instruction*, 16> AddrModeInsts;
4767 const SimplifyQuery SQ(*DL, TLInfo);
4768 AddressingModeCombiner AddrModes(SQ, Addr);
4769 TypePromotionTransaction TPT(RemovedInsts);
4770 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
4771 TPT.getRestorationPoint();
4772 while (!worklist.empty()) {
4773 Value *V = worklist.back();
4774 worklist.pop_back();
4775
4776 // We allow traversing cyclic Phi nodes.
4777 // In case of success after this loop we ensure that traversing through
4778 // Phi nodes ends up with all cases to compute address of the form
4779 // BaseGV + Base + Scale * Index + Offset
4780 // where Scale and Offset are constans and BaseGV, Base and Index
4781 // are exactly the same Values in all cases.
4782 // It means that BaseGV, Scale and Offset dominate our memory instruction
4783 // and have the same value as they had in address computation represented
4784 // as Phi. So we can safely sink address computation to memory instruction.
4785 if (!Visited.insert(V).second)
4786 continue;
4787
4788 // For a PHI node, push all of its incoming values.
4789 if (PHINode *P = dyn_cast<PHINode>(V)) {
4790 for (Value *IncValue : P->incoming_values())
4791 worklist.push_back(IncValue);
4792 PhiOrSelectSeen = true;
4793 continue;
4794 }
4795 // Similar for select.
4796 if (SelectInst *SI = dyn_cast<SelectInst>(V)) {
4797 worklist.push_back(SI->getFalseValue());
4798 worklist.push_back(SI->getTrueValue());
4799 PhiOrSelectSeen = true;
4800 continue;
4801 }
4802
4803 // For non-PHIs, determine the addressing mode being computed. Note that
4804 // the result may differ depending on what other uses our candidate
4805 // addressing instructions might have.
4806 AddrModeInsts.clear();
4807 std::pair<AssertingVH<GetElementPtrInst>, int64_t> LargeOffsetGEP(nullptr,
4808 0);
4809 ExtAddrMode NewAddrMode = AddressingModeMatcher::Match(
4810 V, AccessTy, AddrSpace, MemoryInst, AddrModeInsts, *TLI, *TRI,
4811 InsertedInsts, PromotedInsts, TPT, LargeOffsetGEP);
4812
4813 GetElementPtrInst *GEP = LargeOffsetGEP.first;
4814 if (GEP && !NewGEPBases.count(GEP)) {
4815 // If splitting the underlying data structure can reduce the offset of a
4816 // GEP, collect the GEP. Skip the GEPs that are the new bases of
4817 // previously split data structures.
4818 LargeOffsetGEPMap[GEP->getPointerOperand()].push_back(LargeOffsetGEP);
4819 if (LargeOffsetGEPID.find(GEP) == LargeOffsetGEPID.end())
4820 LargeOffsetGEPID[GEP] = LargeOffsetGEPID.size();
4821 }
4822
4823 NewAddrMode.OriginalValue = V;
4824 if (!AddrModes.addNewAddrMode(NewAddrMode))
4825 break;
4826 }
4827
4828 // Try to combine the AddrModes we've collected. If we couldn't collect any,
4829 // or we have multiple but either couldn't combine them or combining them
4830 // wouldn't do anything useful, bail out now.
4831 if (!AddrModes.combineAddrModes()) {
4832 TPT.rollback(LastKnownGood);
4833 return false;
4834 }
4835 TPT.commit();
4836
4837 // Get the combined AddrMode (or the only AddrMode, if we only had one).
4838 ExtAddrMode AddrMode = AddrModes.getAddrMode();
4839
4840 // If all the instructions matched are already in this BB, don't do anything.
4841 // If we saw a Phi node then it is not local definitely, and if we saw a select
4842 // then we want to push the address calculation past it even if it's already
4843 // in this BB.
4844 if (!PhiOrSelectSeen && none_of(AddrModeInsts, [&](Value *V) {
4845 return IsNonLocalValue(V, MemoryInst->getParent());
4846 })) {
4847 LLVM_DEBUG(dbgs() << "CGP: Found local addrmode: " << AddrModedo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: Found local addrmode: "
<< AddrMode << "\n"; } } while (false)
4848 << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: Found local addrmode: "
<< AddrMode << "\n"; } } while (false)
;
4849 return false;
4850 }
4851
4852 // Insert this computation right after this user. Since our caller is
4853 // scanning from the top of the BB to the bottom, reuse of the expr are
4854 // guaranteed to happen later.
4855 IRBuilder<> Builder(MemoryInst);
4856
4857 // Now that we determined the addressing expression we want to use and know
4858 // that we have to sink it into this block. Check to see if we have already
4859 // done this for some other load/store instr in this block. If so, reuse
4860 // the computation. Before attempting reuse, check if the address is valid
4861 // as it may have been erased.
4862
4863 WeakTrackingVH SunkAddrVH = SunkAddrs[Addr];
4864
4865 Value * SunkAddr = SunkAddrVH.pointsToAliveValue() ? SunkAddrVH : nullptr;
4866 if (SunkAddr) {
4867 LLVM_DEBUG(dbgs() << "CGP: Reusing nonlocal addrmode: " << AddrModedo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: Reusing nonlocal addrmode: "
<< AddrMode << " for " << *MemoryInst <<
"\n"; } } while (false)
4868 << " for " << *MemoryInst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: Reusing nonlocal addrmode: "
<< AddrMode << " for " << *MemoryInst <<
"\n"; } } while (false)
;
4869 if (SunkAddr->getType() != Addr->getType())
4870 SunkAddr = Builder.CreatePointerCast(SunkAddr, Addr->getType());
4871 } else if (AddrSinkUsingGEPs || (!AddrSinkUsingGEPs.getNumOccurrences() &&
4872 TM && SubtargetInfo->addrSinkUsingGEPs())) {
4873 // By default, we use the GEP-based method when AA is used later. This
4874 // prevents new inttoptr/ptrtoint pairs from degrading AA capabilities.
4875 LLVM_DEBUG(dbgs() << "CGP: SINKING nonlocal addrmode: " << AddrModedo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: SINKING nonlocal addrmode: "
<< AddrMode << " for " << *MemoryInst <<
"\n"; } } while (false)
4876 << " for " << *MemoryInst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: SINKING nonlocal addrmode: "
<< AddrMode << " for " << *MemoryInst <<
"\n"; } } while (false)
;
4877 Type *IntPtrTy = DL->getIntPtrType(Addr->getType());
4878 Value *ResultPtr = nullptr, *ResultIndex = nullptr;
4879
4880 // First, find the pointer.
4881 if (AddrMode.BaseReg && AddrMode.BaseReg->getType()->isPointerTy()) {
4882 ResultPtr = AddrMode.BaseReg;
4883 AddrMode.BaseReg = nullptr;
4884 }
4885
4886 if (AddrMode.Scale && AddrMode.ScaledReg->getType()->isPointerTy()) {
4887 // We can't add more than one pointer together, nor can we scale a
4888 // pointer (both of which seem meaningless).
4889 if (ResultPtr || AddrMode.Scale != 1)
4890 return false;
4891
4892 ResultPtr = AddrMode.ScaledReg;
4893 AddrMode.Scale = 0;
4894 }
4895
4896 // It is only safe to sign extend the BaseReg if we know that the math
4897 // required to create it did not overflow before we extend it. Since
4898 // the original IR value was tossed in favor of a constant back when
4899 // the AddrMode was created we need to bail out gracefully if widths
4900 // do not match instead of extending it.
4901 //
4902 // (See below for code to add the scale.)
4903 if (AddrMode.Scale) {
4904 Type *ScaledRegTy = AddrMode.ScaledReg->getType();
4905 if (cast<IntegerType>(IntPtrTy)->getBitWidth() >
4906 cast<IntegerType>(ScaledRegTy)->getBitWidth())
4907 return false;
4908 }
4909
4910 if (AddrMode.BaseGV) {
4911 if (ResultPtr)
4912 return false;
4913
4914 ResultPtr = AddrMode.BaseGV;
4915 }
4916
4917 // If the real base value actually came from an inttoptr, then the matcher
4918 // will look through it and provide only the integer value. In that case,
4919 // use it here.
4920 if (!DL->isNonIntegralPointerType(Addr->getType())) {
4921 if (!ResultPtr && AddrMode.BaseReg) {
4922 ResultPtr = Builder.CreateIntToPtr(AddrMode.BaseReg, Addr->getType(),
4923 "sunkaddr");
4924 AddrMode.BaseReg = nullptr;
4925 } else if (!ResultPtr && AddrMode.Scale == 1) {
4926 ResultPtr = Builder.CreateIntToPtr(AddrMode.ScaledReg, Addr->getType(),
4927 "sunkaddr");
4928 AddrMode.Scale = 0;
4929 }
4930 }
4931
4932 if (!ResultPtr &&
4933 !AddrMode.BaseReg && !AddrMode.Scale && !AddrMode.BaseOffs) {
4934 SunkAddr = Constant::getNullValue(Addr->getType());
4935 } else if (!ResultPtr) {
4936 return false;
4937 } else {
4938 Type *I8PtrTy =
4939 Builder.getInt8PtrTy(Addr->getType()->getPointerAddressSpace());
4940 Type *I8Ty = Builder.getInt8Ty();
4941
4942 // Start with the base register. Do this first so that subsequent address
4943 // matching finds it last, which will prevent it from trying to match it
4944 // as the scaled value in case it happens to be a mul. That would be
4945 // problematic if we've sunk a different mul for the scale, because then
4946 // we'd end up sinking both muls.
4947 if (AddrMode.BaseReg) {
4948 Value *V = AddrMode.BaseReg;
4949 if (V->getType() != IntPtrTy)
4950 V = Builder.CreateIntCast(V, IntPtrTy, /*isSigned=*/true, "sunkaddr");
4951
4952 ResultIndex = V;
4953 }
4954
4955 // Add the scale value.
4956 if (AddrMode.Scale) {
4957 Value *V = AddrMode.ScaledReg;
4958 if (V->getType() == IntPtrTy) {
4959 // done.
4960 } else {
4961 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-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 4963, __PRETTY_FUNCTION__))
4962 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-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 4963, __PRETTY_FUNCTION__))
4963 "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-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 4963, __PRETTY_FUNCTION__))
;
4964 V = Builder.CreateTrunc(V, IntPtrTy, "sunkaddr");
4965 }
4966
4967 if (AddrMode.Scale != 1)
4968 V = Builder.CreateMul(V, ConstantInt::get(IntPtrTy, AddrMode.Scale),
4969 "sunkaddr");
4970 if (ResultIndex)
4971 ResultIndex = Builder.CreateAdd(ResultIndex, V, "sunkaddr");
4972 else
4973 ResultIndex = V;
4974 }
4975
4976 // Add in the Base Offset if present.
4977 if (AddrMode.BaseOffs) {
4978 Value *V = ConstantInt::get(IntPtrTy, AddrMode.BaseOffs);
4979 if (ResultIndex) {
4980 // We need to add this separately from the scale above to help with
4981 // SDAG consecutive load/store merging.
4982 if (ResultPtr->getType() != I8PtrTy)
4983 ResultPtr = Builder.CreatePointerCast(ResultPtr, I8PtrTy);
4984 ResultPtr =
4985 AddrMode.InBounds
4986 ? Builder.CreateInBoundsGEP(I8Ty, ResultPtr, ResultIndex,
4987 "sunkaddr")
4988 : Builder.CreateGEP(I8Ty, ResultPtr, ResultIndex, "sunkaddr");
4989 }
4990
4991 ResultIndex = V;
4992 }
4993
4994 if (!ResultIndex) {
4995 SunkAddr = ResultPtr;
4996 } else {
4997 if (ResultPtr->getType() != I8PtrTy)
4998 ResultPtr = Builder.CreatePointerCast(ResultPtr, I8PtrTy);
4999 SunkAddr =
5000 AddrMode.InBounds
5001 ? Builder.CreateInBoundsGEP(I8Ty, ResultPtr, ResultIndex,
5002 "sunkaddr")
5003 : Builder.CreateGEP(I8Ty, ResultPtr, ResultIndex, "sunkaddr");
5004 }
5005
5006 if (SunkAddr->getType() != Addr->getType())
5007 SunkAddr = Builder.CreatePointerCast(SunkAddr, Addr->getType());
5008 }
5009 } else {
5010 // We'd require a ptrtoint/inttoptr down the line, which we can't do for
5011 // non-integral pointers, so in that case bail out now.
5012 Type *BaseTy = AddrMode.BaseReg ? AddrMode.BaseReg->getType() : nullptr;
5013 Type *ScaleTy = AddrMode.Scale ? AddrMode.ScaledReg->getType() : nullptr;
5014 PointerType *BasePtrTy = dyn_cast_or_null<PointerType>(BaseTy);
5015 PointerType *ScalePtrTy = dyn_cast_or_null<PointerType>(ScaleTy);
5016 if (DL->isNonIntegralPointerType(Addr->getType()) ||
5017 (BasePtrTy && DL->isNonIntegralPointerType(BasePtrTy)) ||
5018 (ScalePtrTy && DL->isNonIntegralPointerType(ScalePtrTy)) ||
5019 (AddrMode.BaseGV &&
5020 DL->isNonIntegralPointerType(AddrMode.BaseGV->getType())))
5021 return false;
5022
5023 LLVM_DEBUG(dbgs() << "CGP: SINKING nonlocal addrmode: " << AddrModedo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: SINKING nonlocal addrmode: "
<< AddrMode << " for " << *MemoryInst <<
"\n"; } } while (false)
5024 << " for " << *MemoryInst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: SINKING nonlocal addrmode: "
<< AddrMode << " for " << *MemoryInst <<
"\n"; } } while (false)
;
5025 Type *IntPtrTy = DL->getIntPtrType(Addr->getType());
5026 Value *Result = nullptr;
5027
5028 // Start with the base register. Do this first so that subsequent address
5029 // matching finds it last, which will prevent it from trying to match it
5030 // as the scaled value in case it happens to be a mul. That would be
5031 // problematic if we've sunk a different mul for the scale, because then
5032 // we'd end up sinking both muls.
5033 if (AddrMode.BaseReg) {
5034 Value *V = AddrMode.BaseReg;
5035 if (V->getType()->isPointerTy())
5036 V = Builder.CreatePtrToInt(V, IntPtrTy, "sunkaddr");
5037 if (V->getType() != IntPtrTy)
5038 V = Builder.CreateIntCast(V, IntPtrTy, /*isSigned=*/true, "sunkaddr");
5039 Result = V;
5040 }
5041
5042 // Add the scale value.
5043 if (AddrMode.Scale) {
5044 Value *V = AddrMode.ScaledReg;
5045 if (V->getType() == IntPtrTy) {
5046 // done.
5047 } else if (V->getType()->isPointerTy()) {
5048 V = Builder.CreatePtrToInt(V, IntPtrTy, "sunkaddr");
5049 } else if (cast<IntegerType>(IntPtrTy)->getBitWidth() <
5050 cast<IntegerType>(V->getType())->getBitWidth()) {
5051 V = Builder.CreateTrunc(V, IntPtrTy, "sunkaddr");
5052 } else {
5053 // It is only safe to sign extend the BaseReg if we know that the math
5054 // required to create it did not overflow before we extend it. Since
5055 // the original IR value was tossed in favor of a constant back when
5056 // the AddrMode was created we need to bail out gracefully if widths
5057 // do not match instead of extending it.
5058 Instruction *I = dyn_cast_or_null<Instruction>(Result);
5059 if (I && (Result != AddrMode.BaseReg))
5060 I->eraseFromParent();
5061 return false;
5062 }
5063 if (AddrMode.Scale != 1)
5064 V = Builder.CreateMul(V, ConstantInt::get(IntPtrTy, AddrMode.Scale),
5065 "sunkaddr");
5066 if (Result)
5067 Result = Builder.CreateAdd(Result, V, "sunkaddr");
5068 else
5069 Result = V;
5070 }
5071
5072 // Add in the BaseGV if present.
5073 if (AddrMode.BaseGV) {
5074 Value *V = Builder.CreatePtrToInt(AddrMode.BaseGV, IntPtrTy, "sunkaddr");
5075 if (Result)
5076 Result = Builder.CreateAdd(Result, V, "sunkaddr");
5077 else
5078 Result = V;
5079 }
5080
5081 // Add in the Base Offset if present.
5082 if (AddrMode.BaseOffs) {
5083 Value *V = ConstantInt::get(IntPtrTy, AddrMode.BaseOffs);
5084 if (Result)
5085 Result = Builder.CreateAdd(Result, V, "sunkaddr");
5086 else
5087 Result = V;
5088 }
5089
5090 if (!Result)
5091 SunkAddr = Constant::getNullValue(Addr->getType());
5092 else
5093 SunkAddr = Builder.CreateIntToPtr(Result, Addr->getType(), "sunkaddr");
5094 }
5095
5096 MemoryInst->replaceUsesOfWith(Repl, SunkAddr);
5097 // Store the newly computed address into the cache. In the case we reused a
5098 // value, this should be idempotent.
5099 SunkAddrs[Addr] = WeakTrackingVH(SunkAddr);
5100
5101 // If we have no uses, recursively delete the value and all dead instructions
5102 // using it.
5103 if (Repl->use_empty()) {
5104 // This can cause recursive deletion, which can invalidate our iterator.
5105 // Use a WeakTrackingVH to hold onto it in case this happens.
5106 Value *CurValue = &*CurInstIterator;
5107 WeakTrackingVH IterHandle(CurValue);
5108 BasicBlock *BB = CurInstIterator->getParent();
5109
5110 RecursivelyDeleteTriviallyDeadInstructions(Repl, TLInfo);
5111
5112 if (IterHandle != CurValue) {
5113 // If the iterator instruction was recursively deleted, start over at the
5114 // start of the block.
5115 CurInstIterator = BB->begin();
5116 SunkAddrs.clear();
5117 }
5118 }
5119 ++NumMemoryInsts;
5120 return true;
5121}
5122
5123/// If there are any memory operands, use OptimizeMemoryInst to sink their
5124/// address computing into the block when possible / profitable.
5125bool CodeGenPrepare::optimizeInlineAsmInst(CallInst *CS) {
5126 bool MadeChange = false;
5127
5128 const TargetRegisterInfo *TRI =
5129 TM->getSubtargetImpl(*CS->getFunction())->getRegisterInfo();
5130 TargetLowering::AsmOperandInfoVector TargetConstraints =
5131 TLI->ParseConstraints(*DL, TRI, CS);
5132 unsigned ArgNo = 0;
5133 for (unsigned i = 0, e = TargetConstraints.size(); i != e; ++i) {
5134 TargetLowering::AsmOperandInfo &OpInfo = TargetConstraints[i];
5135
5136 // Compute the constraint code and ConstraintType to use.
5137 TLI->ComputeConstraintToUse(OpInfo, SDValue());
5138
5139 if (OpInfo.ConstraintType == TargetLowering::C_Memory &&
5140 OpInfo.isIndirect) {
5141 Value *OpVal = CS->getArgOperand(ArgNo++);
5142 MadeChange |= optimizeMemoryInst(CS, OpVal, OpVal->getType(), ~0u);
5143 } else if (OpInfo.Type == InlineAsm::isInput)
5144 ArgNo++;
5145 }
5146
5147 return MadeChange;
5148}
5149
5150/// Check if all the uses of \p Val are equivalent (or free) zero or
5151/// sign extensions.
5152static bool hasSameExtUse(Value *Val, const TargetLowering &TLI) {
5153 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-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 5153, __PRETTY_FUNCTION__))
;
5154 const Instruction *FirstUser = cast<Instruction>(*Val->user_begin());
5155 bool IsSExt = isa<SExtInst>(FirstUser);
5156 Type *ExtTy = FirstUser->getType();
5157 for (const User *U : Val->users()) {
5158 const Instruction *UI = cast<Instruction>(U);
5159 if ((IsSExt && !isa<SExtInst>(UI)) || (!IsSExt && !isa<ZExtInst>(UI)))
5160 return false;
5161 Type *CurTy = UI->getType();
5162 // Same input and output types: Same instruction after CSE.
5163 if (CurTy == ExtTy)
5164 continue;
5165
5166 // If IsSExt is true, we are in this situation:
5167 // a = Val
5168 // b = sext ty1 a to ty2
5169 // c = sext ty1 a to ty3
5170 // Assuming ty2 is shorter than ty3, this could be turned into:
5171 // a = Val
5172 // b = sext ty1 a to ty2
5173 // c = sext ty2 b to ty3
5174 // However, the last sext is not free.
5175 if (IsSExt)
5176 return false;
5177
5178 // This is a ZExt, maybe this is free to extend from one type to another.
5179 // In that case, we would not account for a different use.
5180 Type *NarrowTy;
5181 Type *LargeTy;
5182 if (ExtTy->getScalarType()->getIntegerBitWidth() >
5183 CurTy->getScalarType()->getIntegerBitWidth()) {
5184 NarrowTy = CurTy;
5185 LargeTy = ExtTy;
5186 } else {
5187 NarrowTy = ExtTy;
5188 LargeTy = CurTy;
5189 }
5190
5191 if (!TLI.isZExtFree(NarrowTy, LargeTy))
5192 return false;
5193 }
5194 // All uses are the same or can be derived from one another for free.
5195 return true;
5196}
5197
5198/// Try to speculatively promote extensions in \p Exts and continue
5199/// promoting through newly promoted operands recursively as far as doing so is
5200/// profitable. Save extensions profitably moved up, in \p ProfitablyMovedExts.
5201/// When some promotion happened, \p TPT contains the proper state to revert
5202/// them.
5203///
5204/// \return true if some promotion happened, false otherwise.
5205bool CodeGenPrepare::tryToPromoteExts(
5206 TypePromotionTransaction &TPT, const SmallVectorImpl<Instruction *> &Exts,
5207 SmallVectorImpl<Instruction *> &ProfitablyMovedExts,
5208 unsigned CreatedInstsCost) {
5209 bool Promoted = false;
5210
5211 // Iterate over all the extensions to try to promote them.
5212 for (auto I : Exts) {
5213 // Early check if we directly have ext(load).
5214 if (isa<LoadInst>(I->getOperand(0))) {
5215 ProfitablyMovedExts.push_back(I);
5216 continue;
5217 }
5218
5219 // Check whether or not we want to do any promotion. The reason we have
5220 // this check inside the for loop is to catch the case where an extension
5221 // is directly fed by a load because in such case the extension can be moved
5222 // up without any promotion on its operands.
5223 if (!TLI || !TLI->enableExtLdPromotion() || DisableExtLdPromotion)
5224 return false;
5225
5226 // Get the action to perform the promotion.
5227 TypePromotionHelper::Action TPH =
5228 TypePromotionHelper::getAction(I, InsertedInsts, *TLI, PromotedInsts);
5229 // Check if we can promote.
5230 if (!TPH) {
5231 // Save the current extension as we cannot move up through its operand.
5232 ProfitablyMovedExts.push_back(I);
5233 continue;
5234 }
5235
5236 // Save the current state.
5237 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
5238 TPT.getRestorationPoint();
5239 SmallVector<Instruction *, 4> NewExts;
5240 unsigned NewCreatedInstsCost = 0;
5241 unsigned ExtCost = !TLI->isExtFree(I);
5242 // Promote.
5243 Value *PromotedVal = TPH(I, TPT, PromotedInsts, NewCreatedInstsCost,
5244 &NewExts, nullptr, *TLI);
5245 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-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 5246, __PRETTY_FUNCTION__))
5246 "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-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 5246, __PRETTY_FUNCTION__))
;
5247
5248 // We would be able to merge only one extension in a load.
5249 // Therefore, if we have more than 1 new extension we heuristically
5250 // cut this search path, because it means we degrade the code quality.
5251 // With exactly 2, the transformation is neutral, because we will merge
5252 // one extension but leave one. However, we optimistically keep going,
5253 // because the new extension may be removed too.
5254 long long TotalCreatedInstsCost = CreatedInstsCost + NewCreatedInstsCost;
5255 // FIXME: It would be possible to propagate a negative value instead of
5256 // conservatively ceiling it to 0.
5257 TotalCreatedInstsCost =
5258 std::max((long long)0, (TotalCreatedInstsCost - ExtCost));
5259 if (!StressExtLdPromotion &&
5260 (TotalCreatedInstsCost > 1 ||
5261 !isPromotedInstructionLegal(*TLI, *DL, PromotedVal))) {
5262 // This promotion is not profitable, rollback to the previous state, and
5263 // save the current extension in ProfitablyMovedExts as the latest
5264 // speculative promotion turned out to be unprofitable.
5265 TPT.rollback(LastKnownGood);
5266 ProfitablyMovedExts.push_back(I);
5267 continue;
5268 }
5269 // Continue promoting NewExts as far as doing so is profitable.
5270 SmallVector<Instruction *, 2> NewlyMovedExts;
5271 (void)tryToPromoteExts(TPT, NewExts, NewlyMovedExts, TotalCreatedInstsCost);
5272 bool NewPromoted = false;
5273 for (auto ExtInst : NewlyMovedExts) {
5274 Instruction *MovedExt = cast<Instruction>(ExtInst);
5275 Value *ExtOperand = MovedExt->getOperand(0);
5276 // If we have reached to a load, we need this extra profitability check
5277 // as it could potentially be merged into an ext(load).
5278 if (isa<LoadInst>(ExtOperand) &&
5279 !(StressExtLdPromotion || NewCreatedInstsCost <= ExtCost ||
5280 (ExtOperand->hasOneUse() || hasSameExtUse(ExtOperand, *TLI))))
5281 continue;
5282
5283 ProfitablyMovedExts.push_back(MovedExt);
5284 NewPromoted = true;
5285 }
5286
5287 // If none of speculative promotions for NewExts is profitable, rollback
5288 // and save the current extension (I) as the last profitable extension.
5289 if (!NewPromoted) {
5290 TPT.rollback(LastKnownGood);
5291 ProfitablyMovedExts.push_back(I);
5292 continue;
5293 }
5294 // The promotion is profitable.
5295 Promoted = true;
5296 }
5297 return Promoted;
5298}
5299
5300/// Merging redundant sexts when one is dominating the other.
5301bool CodeGenPrepare::mergeSExts(Function &F) {
5302 bool Changed = false;
5303 for (auto &Entry : ValToSExtendedUses) {
5304 SExts &Insts = Entry.second;
5305 SExts CurPts;
5306 for (Instruction *Inst : Insts) {
5307 if (RemovedInsts.count(Inst) || !isa<SExtInst>(Inst) ||
5308 Inst->getOperand(0) != Entry.first)
5309 continue;
5310 bool inserted = false;
5311 for (auto &Pt : CurPts) {
5312 if (getDT(F).dominates(Inst, Pt)) {
5313 Pt->replaceAllUsesWith(Inst);
5314 RemovedInsts.insert(Pt);
5315 Pt->removeFromParent();
5316 Pt = Inst;
5317 inserted = true;
5318 Changed = true;
5319 break;
5320 }
5321 if (!getDT(F).dominates(Pt, Inst))
5322 // Give up if we need to merge in a common dominator as the
5323 // experiments show it is not profitable.
5324 continue;
5325 Inst->replaceAllUsesWith(Pt);
5326 RemovedInsts.insert(Inst);
5327 Inst->removeFromParent();
5328 inserted = true;
5329 Changed = true;
5330 break;
5331 }
5332 if (!inserted)
5333 CurPts.push_back(Inst);
5334 }
5335 }
5336 return Changed;
5337}
5338
5339// Spliting large data structures so that the GEPs accessing them can have
5340// smaller offsets so that they can be sunk to the same blocks as their users.
5341// For example, a large struct starting from %base is splitted into two parts
5342// where the second part starts from %new_base.
5343//
5344// Before:
5345// BB0:
5346// %base =
5347//
5348// BB1:
5349// %gep0 = gep %base, off0
5350// %gep1 = gep %base, off1
5351// %gep2 = gep %base, off2
5352//
5353// BB2:
5354// %load1 = load %gep0
5355// %load2 = load %gep1
5356// %load3 = load %gep2
5357//
5358// After:
5359// BB0:
5360// %base =
5361// %new_base = gep %base, off0
5362//
5363// BB1:
5364// %new_gep0 = %new_base
5365// %new_gep1 = gep %new_base, off1 - off0
5366// %new_gep2 = gep %new_base, off2 - off0
5367//
5368// BB2:
5369// %load1 = load i32, i32* %new_gep0
5370// %load2 = load i32, i32* %new_gep1
5371// %load3 = load i32, i32* %new_gep2
5372//
5373// %new_gep1 and %new_gep2 can be sunk to BB2 now after the splitting because
5374// their offsets are smaller enough to fit into the addressing mode.
5375bool CodeGenPrepare::splitLargeGEPOffsets() {
5376 bool Changed = false;
5377 for (auto &Entry : LargeOffsetGEPMap) {
5378 Value *OldBase = Entry.first;
5379 SmallVectorImpl<std::pair<AssertingVH<GetElementPtrInst>, int64_t>>
5380 &LargeOffsetGEPs = Entry.second;
5381 auto compareGEPOffset =
5382 [&](const std::pair<GetElementPtrInst *, int64_t> &LHS,
5383 const std::pair<GetElementPtrInst *, int64_t> &RHS) {
5384 if (LHS.first == RHS.first)
5385 return false;
5386 if (LHS.second != RHS.second)
5387 return LHS.second < RHS.second;
5388 return LargeOffsetGEPID[LHS.first] < LargeOffsetGEPID[RHS.first];
5389 };
5390 // Sorting all the GEPs of the same data structures based on the offsets.
5391 llvm::sort(LargeOffsetGEPs, compareGEPOffset);
5392 LargeOffsetGEPs.erase(
5393 std::unique(LargeOffsetGEPs.begin(), LargeOffsetGEPs.end()),
5394 LargeOffsetGEPs.end());
5395 // Skip if all the GEPs have the same offsets.
5396 if (LargeOffsetGEPs.front().second == LargeOffsetGEPs.back().second)
5397 continue;
5398 GetElementPtrInst *BaseGEP = LargeOffsetGEPs.begin()->first;
5399 int64_t BaseOffset = LargeOffsetGEPs.begin()->second;
5400 Value *NewBaseGEP = nullptr;
5401
5402 auto LargeOffsetGEP = LargeOffsetGEPs.begin();
5403 while (LargeOffsetGEP != LargeOffsetGEPs.end()) {
5404 GetElementPtrInst *GEP = LargeOffsetGEP->first;
5405 int64_t Offset = LargeOffsetGEP->second;
5406 if (Offset != BaseOffset) {
5407 TargetLowering::AddrMode AddrMode;
5408 AddrMode.BaseOffs = Offset - BaseOffset;
5409 // The result type of the GEP might not be the type of the memory
5410 // access.
5411 if (!TLI->isLegalAddressingMode(*DL, AddrMode,
5412 GEP->getResultElementType(),
5413 GEP->getAddressSpace())) {
5414 // We need to create a new base if the offset to the current base is
5415 // too large to fit into the addressing mode. So, a very large struct
5416 // may be splitted into several parts.
5417 BaseGEP = GEP;
5418 BaseOffset = Offset;
5419 NewBaseGEP = nullptr;
5420 }
5421 }
5422
5423 // Generate a new GEP to replace the current one.
5424 LLVMContext &Ctx = GEP->getContext();
5425 Type *IntPtrTy = DL->getIntPtrType(GEP->getType());
5426 Type *I8PtrTy =
5427 Type::getInt8PtrTy(Ctx, GEP->getType()->getPointerAddressSpace());
5428 Type *I8Ty = Type::getInt8Ty(Ctx);
5429
5430 if (!NewBaseGEP) {
5431 // Create a new base if we don't have one yet. Find the insertion
5432 // pointer for the new base first.
5433 BasicBlock::iterator NewBaseInsertPt;
5434 BasicBlock *NewBaseInsertBB;
5435 if (auto *BaseI = dyn_cast<Instruction>(OldBase)) {
5436 // If the base of the struct is an instruction, the new base will be
5437 // inserted close to it.
5438 NewBaseInsertBB = BaseI->getParent();
5439 if (isa<PHINode>(BaseI))
5440 NewBaseInsertPt = NewBaseInsertBB->getFirstInsertionPt();
5441 else if (InvokeInst *Invoke = dyn_cast<InvokeInst>(BaseI)) {
5442 NewBaseInsertBB =
5443 SplitEdge(NewBaseInsertBB, Invoke->getNormalDest());
5444 NewBaseInsertPt = NewBaseInsertBB->getFirstInsertionPt();
5445 } else
5446 NewBaseInsertPt = std::next(BaseI->getIterator());
5447 } else {
5448 // If the current base is an argument or global value, the new base
5449 // will be inserted to the entry block.
5450 NewBaseInsertBB = &BaseGEP->getFunction()->getEntryBlock();
5451 NewBaseInsertPt = NewBaseInsertBB->getFirstInsertionPt();
5452 }
5453 IRBuilder<> NewBaseBuilder(NewBaseInsertBB, NewBaseInsertPt);
5454 // Create a new base.
5455 Value *BaseIndex = ConstantInt::get(IntPtrTy, BaseOffset);
5456 NewBaseGEP = OldBase;
5457 if (NewBaseGEP->getType() != I8PtrTy)
5458 NewBaseGEP = NewBaseBuilder.CreatePointerCast(NewBaseGEP, I8PtrTy);
5459 NewBaseGEP =
5460 NewBaseBuilder.CreateGEP(I8Ty, NewBaseGEP, BaseIndex, "splitgep");
5461 NewGEPBases.insert(NewBaseGEP);
5462 }
5463
5464 IRBuilder<> Builder(GEP);
5465 Value *NewGEP = NewBaseGEP;
5466 if (Offset == BaseOffset) {
5467 if (GEP->getType() != I8PtrTy)
5468 NewGEP = Builder.CreatePointerCast(NewGEP, GEP->getType());
5469 } else {
5470 // Calculate the new offset for the new GEP.
5471 Value *Index = ConstantInt::get(IntPtrTy, Offset - BaseOffset);
5472 NewGEP = Builder.CreateGEP(I8Ty, NewBaseGEP, Index);
5473
5474 if (GEP->getType() != I8PtrTy)
5475 NewGEP = Builder.CreatePointerCast(NewGEP, GEP->getType());
5476 }
5477 GEP->replaceAllUsesWith(NewGEP);
5478 LargeOffsetGEPID.erase(GEP);
5479 LargeOffsetGEP = LargeOffsetGEPs.erase(LargeOffsetGEP);
5480 GEP->eraseFromParent();
5481 Changed = true;
5482 }
5483 }
5484 return Changed;
5485}
5486
5487/// Return true, if an ext(load) can be formed from an extension in
5488/// \p MovedExts.
5489bool CodeGenPrepare::canFormExtLd(
5490 const SmallVectorImpl<Instruction *> &MovedExts, LoadInst *&LI,
5491 Instruction *&Inst, bool HasPromoted) {
5492 for (auto *MovedExtInst : MovedExts) {
5493 if (isa<LoadInst>(MovedExtInst->getOperand(0))) {
5494 LI = cast<LoadInst>(MovedExtInst->getOperand(0));
5495 Inst = MovedExtInst;
5496 break;
5497 }
5498 }
5499 if (!LI)
5500 return false;
5501
5502 // If they're already in the same block, there's nothing to do.
5503 // Make the cheap checks first if we did not promote.
5504 // If we promoted, we need to check if it is indeed profitable.
5505 if (!HasPromoted && LI->getParent() == Inst->getParent())
5506 return false;
5507
5508 return TLI->isExtLoad(LI, Inst, *DL);
5509}
5510
5511/// Move a zext or sext fed by a load into the same basic block as the load,
5512/// unless conditions are unfavorable. This allows SelectionDAG to fold the
5513/// extend into the load.
5514///
5515/// E.g.,
5516/// \code
5517/// %ld = load i32* %addr
5518/// %add = add nuw i32 %ld, 4
5519/// %zext = zext i32 %add to i64
5520// \endcode
5521/// =>
5522/// \code
5523/// %ld = load i32* %addr
5524/// %zext = zext i32 %ld to i64
5525/// %add = add nuw i64 %zext, 4
5526/// \encode
5527/// Note that the promotion in %add to i64 is done in tryToPromoteExts(), which
5528/// allow us to match zext(load i32*) to i64.
5529///
5530/// Also, try to promote the computations used to obtain a sign extended
5531/// value used into memory accesses.
5532/// E.g.,
5533/// \code
5534/// a = add nsw i32 b, 3
5535/// d = sext i32 a to i64
5536/// e = getelementptr ..., i64 d
5537/// \endcode
5538/// =>
5539/// \code
5540/// f = sext i32 b to i64
5541/// a = add nsw i64 f, 3
5542/// e = getelementptr ..., i64 a
5543/// \endcode
5544///
5545/// \p Inst[in/out] the extension may be modified during the process if some
5546/// promotions apply.
5547bool CodeGenPrepare::optimizeExt(Instruction *&Inst) {
5548 // ExtLoad formation and address type promotion infrastructure requires TLI to
5549 // be effective.
5550 if (!TLI)
5551 return false;
5552
5553 bool AllowPromotionWithoutCommonHeader = false;
5554 /// See if it is an interesting sext operations for the address type
5555 /// promotion before trying to promote it, e.g., the ones with the right
5556 /// type and used in memory accesses.
5557 bool ATPConsiderable = TTI->shouldConsiderAddressTypePromotion(
5558 *Inst, AllowPromotionWithoutCommonHeader);
5559 TypePromotionTransaction TPT(RemovedInsts);
5560 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
5561 TPT.getRestorationPoint();
5562 SmallVector<Instruction *, 1> Exts;
5563 SmallVector<Instruction *, 2> SpeculativelyMovedExts;
5564 Exts.push_back(Inst);
5565
5566 bool HasPromoted = tryToPromoteExts(TPT, Exts, SpeculativelyMovedExts);
5567
5568 // Look for a load being extended.
5569 LoadInst *LI = nullptr;
5570 Instruction *ExtFedByLoad;
5571
5572 // Try to promote a chain of computation if it allows to form an extended
5573 // load.
5574 if (canFormExtLd(SpeculativelyMovedExts, LI, ExtFedByLoad, HasPromoted)) {
5575 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-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 5575, __PRETTY_FUNCTION__))
;
5576 TPT.commit();
5577 // Move the extend into the same block as the load
5578 ExtFedByLoad->moveAfter(LI);
5579 // CGP does not check if the zext would be speculatively executed when moved
5580 // to the same basic block as the load. Preserving its original location
5581 // would pessimize the debugging experience, as well as negatively impact
5582 // the quality of sample pgo. We don't want to use "line 0" as that has a
5583 // size cost in the line-table section and logically the zext can be seen as
5584 // part of the load. Therefore we conservatively reuse the same debug
5585 // location for the load and the zext.
5586 ExtFedByLoad->setDebugLoc(LI->getDebugLoc());
5587 ++NumExtsMoved;
5588 Inst = ExtFedByLoad;
5589 return true;
5590 }
5591
5592 // Continue promoting SExts if known as considerable depending on targets.
5593 if (ATPConsiderable &&
5594 performAddressTypePromotion(Inst, AllowPromotionWithoutCommonHeader,
5595 HasPromoted, TPT, SpeculativelyMovedExts))
5596 return true;
5597
5598 TPT.rollback(LastKnownGood);
5599 return false;
5600}
5601
5602// Perform address type promotion if doing so is profitable.
5603// If AllowPromotionWithoutCommonHeader == false, we should find other sext
5604// instructions that sign extended the same initial value. However, if
5605// AllowPromotionWithoutCommonHeader == true, we expect promoting the
5606// extension is just profitable.
5607bool CodeGenPrepare::performAddressTypePromotion(
5608 Instruction *&Inst, bool AllowPromotionWithoutCommonHeader,
5609 bool HasPromoted, TypePromotionTransaction &TPT,
5610 SmallVectorImpl<Instruction *> &SpeculativelyMovedExts) {
5611 bool Promoted = false;
5612 SmallPtrSet<Instruction *, 1> UnhandledExts;
5613 bool AllSeenFirst = true;
5614 for (auto I : SpeculativelyMovedExts) {
5615 Value *HeadOfChain = I->getOperand(0);
5616 DenseMap<Value *, Instruction *>::iterator AlreadySeen =
5617 SeenChainsForSExt.find(HeadOfChain);
5618 // If there is an unhandled SExt which has the same header, try to promote
5619 // it as well.
5620 if (AlreadySeen != SeenChainsForSExt.end()) {
5621 if (AlreadySeen->second != nullptr)
5622 UnhandledExts.insert(AlreadySeen->second);
5623 AllSeenFirst = false;
5624 }
5625 }
5626
5627 if (!AllSeenFirst || (AllowPromotionWithoutCommonHeader &&
5628 SpeculativelyMovedExts.size() == 1)) {
5629 TPT.commit();
5630 if (HasPromoted)
5631 Promoted = true;
5632 for (auto I : SpeculativelyMovedExts) {
5633 Value *HeadOfChain = I->getOperand(0);
5634 SeenChainsForSExt[HeadOfChain] = nullptr;
5635 ValToSExtendedUses[HeadOfChain].push_back(I);
5636 }
5637 // Update Inst as promotion happen.
5638 Inst = SpeculativelyMovedExts.pop_back_val();
5639 } else {
5640 // This is the first chain visited from the header, keep the current chain
5641 // as unhandled. Defer to promote this until we encounter another SExt
5642 // chain derived from the same header.
5643 for (auto I : SpeculativelyMovedExts) {
5644 Value *HeadOfChain = I->getOperand(0);
5645 SeenChainsForSExt[HeadOfChain] = Inst;
5646 }
5647 return false;
5648 }
5649
5650 if (!AllSeenFirst && !UnhandledExts.empty())
5651 for (auto VisitedSExt : UnhandledExts) {
5652 if (RemovedInsts.count(VisitedSExt))
5653 continue;
5654 TypePromotionTransaction TPT(RemovedInsts);
5655 SmallVector<Instruction *, 1> Exts;
5656 SmallVector<Instruction *, 2> Chains;
5657 Exts.push_back(VisitedSExt);
5658 bool HasPromoted = tryToPromoteExts(TPT, Exts, Chains);
5659 TPT.commit();
5660 if (HasPromoted)
5661 Promoted = true;
5662 for (auto I : Chains) {
5663 Value *HeadOfChain = I->getOperand(0);
5664 // Mark this as handled.
5665 SeenChainsForSExt[HeadOfChain] = nullptr;
5666 ValToSExtendedUses[HeadOfChain].push_back(I);
5667 }
5668 }
5669 return Promoted;
5670}
5671
5672bool CodeGenPrepare::optimizeExtUses(Instruction *I) {
5673 BasicBlock *DefBB = I->getParent();
5674
5675 // If the result of a {s|z}ext and its source are both live out, rewrite all
5676 // other uses of the source with result of extension.
5677 Value *Src = I->getOperand(0);
5678 if (Src->hasOneUse())
5679 return false;
5680
5681 // Only do this xform if truncating is free.
5682 if (TLI && !TLI->isTruncateFree(I->getType(), Src->getType()))
5683 return false;
5684
5685 // Only safe to perform the optimization if the source is also defined in
5686 // this block.
5687 if (!isa<Instruction>(Src) || DefBB != cast<Instruction>(Src)->getParent())
5688 return false;
5689
5690 bool DefIsLiveOut = false;
5691 for (User *U : I->users()) {
5692 Instruction *UI = cast<Instruction>(U);
5693
5694 // Figure out which BB this ext is used in.
5695 BasicBlock *UserBB = UI->getParent();
5696 if (UserBB == DefBB) continue;
5697 DefIsLiveOut = true;
5698 break;
5699 }
5700 if (!DefIsLiveOut)
5701 return false;
5702
5703 // Make sure none of the uses are PHI nodes.
5704 for (User *U : Src->users()) {
5705 Instruction *UI = cast<Instruction>(U);
5706 BasicBlock *UserBB = UI->getParent();
5707 if (UserBB == DefBB) continue;
5708 // Be conservative. We don't want this xform to end up introducing
5709 // reloads just before load / store instructions.
5710 if (isa<PHINode>(UI) || isa<LoadInst>(UI) || isa<StoreInst>(UI))
5711 return false;
5712 }
5713
5714 // InsertedTruncs - Only insert one trunc in each block once.
5715 DenseMap<BasicBlock*, Instruction*> InsertedTruncs;
5716
5717 bool MadeChange = false;
5718 for (Use &U : Src->uses()) {
5719 Instruction *User = cast<Instruction>(U.getUser());
5720
5721 // Figure out which BB this ext is used in.
5722 BasicBlock *UserBB = User->getParent();
5723 if (UserBB == DefBB) continue;
5724
5725 // Both src and def are live in this block. Rewrite the use.
5726 Instruction *&InsertedTrunc = InsertedTruncs[UserBB];
5727
5728 if (!InsertedTrunc) {
5729 BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
5730 assert(InsertPt != UserBB->end())((InsertPt != UserBB->end()) ? static_cast<void> (0)
: __assert_fail ("InsertPt != UserBB->end()", "/build/llvm-toolchain-snapshot-10~+201911111502510600c19528f1809/llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 5730, __PRETTY_FUNCTION__))
;
5731 InsertedTrunc = new TruncInst(I, Src->getType(), "", &*InsertPt);
5732 InsertedInsts.insert(InsertedTrunc);
5733 }
5734
5735 // Replace a use of the {s|z}ext source with a use of the result.
5736 U = InsertedTrunc;
5737 ++NumExtUses;
5738 MadeChange = true;
5739 }
5740
5741 return MadeChange;
5742}
5743
5744// Find loads whose uses only use some of the loaded value's bits. Add an "and"
5745// just after the load if the target can fold this into one extload instruction,
5746// with the hope of eliminating some of the other later "and" instructions using
5747// the loaded value. "and"s that are made trivially redundant by the insertion
5748// of the new "and" are removed by this function, while others (e.g. those whose
5749// path from the load goes through a phi) are left for isel to potentially
5750// remove.
5751//
5752// For example:
5753//
5754// b0:
5755// x = load i32
5756// ...
5757// b1:
5758// y = and x, 0xff
5759// z = use y
5760//
5761// becomes:
5762//
5763// b0:
5764// x = load i32
5765// x' = and x, 0xff
5766// ...
5767// b1:
5768// z = use x'
5769//
5770// whereas:
5771//
5772// b0:
5773// x1 = load i32
5774// ...
5775// b1:
5776// x2 = load i32
5777// ...
5778// b2:
5779// x = phi x1, x2
5780// y = and x, 0xff
5781//
5782// becomes (after a call to optimizeLoadExt for each load):
5783//
5784// b0:
5785// x1 = load i32
5786// x1' = and x1, 0xff
5787// ...
5788// b1:
5789// x2 = load i32
5790// x2' = and x2, 0xff
5791// ...
5792// b2:
5793// x = phi x1', x2'
5794// y = and x, 0xff
5795bool CodeGenPrepare::optimizeLoadExt(LoadInst *Load) {
5796 if (!Load->isSimple() || !Load->getType()->isIntOrPtrTy())
5797 return false;
5798
5799 // Skip loads we've already transformed.
5800 if (Load->hasOneUse() &&
5801 InsertedInsts.count(cast<Instruction>(*Load->user_begin())))
5802 return false;
5803
5804 // Look at all uses of Load, looking through phis, to determine how many bits
5805 // of the loaded value are needed.
5806 SmallVector<Instruction *, 8> WorkList;
5807 SmallPtrSet<Instruction *, 16> Visited;
5808 SmallVector<Instruction *, 8> AndsToMaybeRemove;
5809 for (auto *U : Load->users())
5810 WorkList.push_back(cast<Instruction>(U));
5811
5812 EVT LoadResultVT = TLI->getValueType(*DL, Load->getType());
5813 unsigned BitWidth = LoadResultVT.getSizeInBits();
5814 APInt DemandBits(BitWidth, 0);
5815 APInt WidestAndBits(BitWidth, 0);
5816
5817 while (!WorkList.empty()) {
5818 Instruction *I = WorkList.back();
5819 WorkList.pop_back();
5820
5821 // Break use-def graph loops.
5822 if (!Visited.insert(I).second)
5823 continue;
5824
5825 // For a PHI node, push all of its users.
5826 if (auto *Phi = dyn_cast<PHINode>(I)) {
5827 for (auto *U : Phi->users())
5828 WorkList.push_back(cast<Instruction>(U));
5829 continue;
5830 }
5831
5832 switch (I->getOpcode()) {
5833 case Instruction::And: {
5834 auto *AndC = dyn_cast<ConstantInt>(I->getOperand(1));
5835 if (!AndC)
5836 return false;