Bug Summary

File:lib/CodeGen/CodeGenPrepare.cpp
Warning:line 915, 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-eagerly-assume -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 -mrelocation-model pic -pic-level 2 -mthread-model posix -fmath-errno -masm-verbose -mconstructor-aliases -munwind-tables -fuse-init-array -target-cpu x86-64 -dwarf-column-info -debugger-tuning=gdb -momit-leaf-frame-pointer -ffunction-sections -fdata-sections -resource-dir /usr/lib/llvm-7/lib/clang/7.0.0 -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-7~svn329677/build-llvm/lib/CodeGen -I /build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen -I /build/llvm-toolchain-snapshot-7~svn329677/build-llvm/include -I /build/llvm-toolchain-snapshot-7~svn329677/include -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/7.3.0/../../../../include/c++/7.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/7.3.0/../../../../include/x86_64-linux-gnu/c++/7.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/7.3.0/../../../../include/x86_64-linux-gnu/c++/7.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/7.3.0/../../../../include/c++/7.3.0/backward -internal-isystem /usr/include/clang/7.0.0/include/ -internal-isystem /usr/local/include -internal-isystem /usr/lib/llvm-7/lib/clang/7.0.0/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++11 -fdeprecated-macro -fdebug-compilation-dir /build/llvm-toolchain-snapshot-7~svn329677/build-llvm/lib/CodeGen -ferror-limit 19 -fmessage-length 0 -fvisibility-inlines-hidden -fobjc-runtime=gcc -fdiagnostics-show-option -vectorize-loops -vectorize-slp -analyzer-checker optin.performance.Padding -analyzer-output=html -analyzer-config stable-report-filename=true -o /tmp/scan-build-2018-04-11-031539-24776-1 -x c++ /build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp

/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp

1//===- CodeGenPrepare.cpp - Prepare a function for code generation --------===//
2//
3// The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This pass munges the code in the input function to better prepare it for
11// SelectionDAG-based code generation. This works around limitations in it's
12// basic-block-at-a-time approach. It should eventually be removed.
13//
14//===----------------------------------------------------------------------===//
15
16#include "llvm/ADT/APInt.h"
17#include "llvm/ADT/ArrayRef.h"
18#include "llvm/ADT/DenseMap.h"
19#include "llvm/ADT/PointerIntPair.h"
20#include "llvm/ADT/STLExtras.h"
21#include "llvm/ADT/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/Analysis/Utils/Local.h"
34#include "llvm/Analysis/ValueTracking.h"
35#include "llvm/CodeGen/Analysis.h"
36#include "llvm/CodeGen/ISDOpcodes.h"
37#include "llvm/CodeGen/SelectionDAGNodes.h"
38#include "llvm/CodeGen/TargetLowering.h"
39#include "llvm/CodeGen/TargetPassConfig.h"
40#include "llvm/CodeGen/TargetSubtargetInfo.h"
41#include "llvm/CodeGen/ValueTypes.h"
42#include "llvm/IR/Argument.h"
43#include "llvm/IR/Attributes.h"
44#include "llvm/IR/BasicBlock.h"
45#include "llvm/IR/CallSite.h"
46#include "llvm/IR/Constant.h"
47#include "llvm/IR/Constants.h"
48#include "llvm/IR/DataLayout.h"
49#include "llvm/IR/DerivedTypes.h"
50#include "llvm/IR/Dominators.h"
51#include "llvm/IR/Function.h"
52#include "llvm/IR/GetElementPtrTypeIterator.h"
53#include "llvm/IR/GlobalValue.h"
54#include "llvm/IR/GlobalVariable.h"
55#include "llvm/IR/IRBuilder.h"
56#include "llvm/IR/InlineAsm.h"
57#include "llvm/IR/InstrTypes.h"
58#include "llvm/IR/Instruction.h"
59#include "llvm/IR/Instructions.h"
60#include "llvm/IR/IntrinsicInst.h"
61#include "llvm/IR/Intrinsics.h"
62#include "llvm/IR/LLVMContext.h"
63#include "llvm/IR/MDBuilder.h"
64#include "llvm/IR/Module.h"
65#include "llvm/IR/Operator.h"
66#include "llvm/IR/PatternMatch.h"
67#include "llvm/IR/Statepoint.h"
68#include "llvm/IR/Type.h"
69#include "llvm/IR/Use.h"
70#include "llvm/IR/User.h"
71#include "llvm/IR/Value.h"
72#include "llvm/IR/ValueHandle.h"
73#include "llvm/IR/ValueMap.h"
74#include "llvm/Pass.h"
75#include "llvm/Support/BlockFrequency.h"
76#include "llvm/Support/BranchProbability.h"
77#include "llvm/Support/Casting.h"
78#include "llvm/Support/CommandLine.h"
79#include "llvm/Support/Compiler.h"
80#include "llvm/Support/Debug.h"
81#include "llvm/Support/ErrorHandling.h"
82#include "llvm/Support/MachineValueType.h"
83#include "llvm/Support/MathExtras.h"
84#include "llvm/Support/raw_ostream.h"
85#include "llvm/Target/TargetMachine.h"
86#include "llvm/Target/TargetOptions.h"
87#include "llvm/Transforms/Utils/BasicBlockUtils.h"
88#include "llvm/Transforms/Utils/BypassSlowDivision.h"
89#include "llvm/Transforms/Utils/SimplifyLibCalls.h"
90#include <algorithm>
91#include <cassert>
92#include <cstdint>
93#include <iterator>
94#include <limits>
95#include <memory>
96#include <utility>
97#include <vector>
98
99using namespace llvm;
100using namespace llvm::PatternMatch;
101
102#define DEBUG_TYPE"codegenprepare" "codegenprepare"
103
104STATISTIC(NumBlocksElim, "Number of blocks eliminated")static llvm::Statistic NumBlocksElim = {"codegenprepare", "NumBlocksElim"
, "Number of blocks eliminated", {0}, {false}}
;
105STATISTIC(NumPHIsElim, "Number of trivial PHIs eliminated")static llvm::Statistic NumPHIsElim = {"codegenprepare", "NumPHIsElim"
, "Number of trivial PHIs eliminated", {0}, {false}}
;
106STATISTIC(NumGEPsElim, "Number of GEPs converted to casts")static llvm::Statistic NumGEPsElim = {"codegenprepare", "NumGEPsElim"
, "Number of GEPs converted to casts", {0}, {false}}
;
107STATISTIC(NumCmpUses, "Number of uses of Cmp expressions replaced with uses of "static llvm::Statistic NumCmpUses = {"codegenprepare", "NumCmpUses"
, "Number of uses of Cmp expressions replaced with uses of " "sunken Cmps"
, {0}, {false}}
108 "sunken Cmps")static llvm::Statistic NumCmpUses = {"codegenprepare", "NumCmpUses"
, "Number of uses of Cmp expressions replaced with uses of " "sunken Cmps"
, {0}, {false}}
;
109STATISTIC(NumCastUses, "Number of uses of Cast expressions replaced with uses "static llvm::Statistic NumCastUses = {"codegenprepare", "NumCastUses"
, "Number of uses of Cast expressions replaced with uses " "of sunken Casts"
, {0}, {false}}
110 "of sunken Casts")static llvm::Statistic NumCastUses = {"codegenprepare", "NumCastUses"
, "Number of uses of Cast expressions replaced with uses " "of sunken Casts"
, {0}, {false}}
;
111STATISTIC(NumMemoryInsts, "Number of memory instructions whose address "static llvm::Statistic NumMemoryInsts = {"codegenprepare", "NumMemoryInsts"
, "Number of memory instructions whose address " "computations were sunk"
, {0}, {false}}
112 "computations were sunk")static llvm::Statistic NumMemoryInsts = {"codegenprepare", "NumMemoryInsts"
, "Number of memory instructions whose address " "computations were sunk"
, {0}, {false}}
;
113STATISTIC(NumMemoryInstsPhiCreated,static llvm::Statistic NumMemoryInstsPhiCreated = {"codegenprepare"
, "NumMemoryInstsPhiCreated", "Number of phis created when address "
"computations were sunk to memory instructions", {0}, {false
}}
114 "Number of phis created when address "static llvm::Statistic NumMemoryInstsPhiCreated = {"codegenprepare"
, "NumMemoryInstsPhiCreated", "Number of phis created when address "
"computations were sunk to memory instructions", {0}, {false
}}
115 "computations were sunk to memory instructions")static llvm::Statistic NumMemoryInstsPhiCreated = {"codegenprepare"
, "NumMemoryInstsPhiCreated", "Number of phis created when address "
"computations were sunk to memory instructions", {0}, {false
}}
;
116STATISTIC(NumMemoryInstsSelectCreated,static llvm::Statistic NumMemoryInstsSelectCreated = {"codegenprepare"
, "NumMemoryInstsSelectCreated", "Number of select created when address "
"computations were sunk to memory instructions", {0}, {false
}}
117 "Number of select created when address "static llvm::Statistic NumMemoryInstsSelectCreated = {"codegenprepare"
, "NumMemoryInstsSelectCreated", "Number of select created when address "
"computations were sunk to memory instructions", {0}, {false
}}
118 "computations were sunk to memory instructions")static llvm::Statistic NumMemoryInstsSelectCreated = {"codegenprepare"
, "NumMemoryInstsSelectCreated", "Number of select created when address "
"computations were sunk to memory instructions", {0}, {false
}}
;
119STATISTIC(NumExtsMoved, "Number of [s|z]ext instructions combined with loads")static llvm::Statistic NumExtsMoved = {"codegenprepare", "NumExtsMoved"
, "Number of [s|z]ext instructions combined with loads", {0},
{false}}
;
120STATISTIC(NumExtUses, "Number of uses of [s|z]ext instructions optimized")static llvm::Statistic NumExtUses = {"codegenprepare", "NumExtUses"
, "Number of uses of [s|z]ext instructions optimized", {0}, {
false}}
;
121STATISTIC(NumAndsAdded,static llvm::Statistic NumAndsAdded = {"codegenprepare", "NumAndsAdded"
, "Number of and mask instructions added to form ext loads", {
0}, {false}}
122 "Number of and mask instructions added to form ext loads")static llvm::Statistic NumAndsAdded = {"codegenprepare", "NumAndsAdded"
, "Number of and mask instructions added to form ext loads", {
0}, {false}}
;
123STATISTIC(NumAndUses, "Number of uses of and mask instructions optimized")static llvm::Statistic NumAndUses = {"codegenprepare", "NumAndUses"
, "Number of uses of and mask instructions optimized", {0}, {
false}}
;
124STATISTIC(NumRetsDup, "Number of return instructions duplicated")static llvm::Statistic NumRetsDup = {"codegenprepare", "NumRetsDup"
, "Number of return instructions duplicated", {0}, {false}}
;
125STATISTIC(NumDbgValueMoved, "Number of debug value instructions moved")static llvm::Statistic NumDbgValueMoved = {"codegenprepare", "NumDbgValueMoved"
, "Number of debug value instructions moved", {0}, {false}}
;
126STATISTIC(NumSelectsExpanded, "Number of selects turned into branches")static llvm::Statistic NumSelectsExpanded = {"codegenprepare"
, "NumSelectsExpanded", "Number of selects turned into branches"
, {0}, {false}}
;
127STATISTIC(NumStoreExtractExposed, "Number of store(extractelement) exposed")static llvm::Statistic NumStoreExtractExposed = {"codegenprepare"
, "NumStoreExtractExposed", "Number of store(extractelement) exposed"
, {0}, {false}}
;
128
129static cl::opt<bool> DisableBranchOpts(
130 "disable-cgp-branch-opts", cl::Hidden, cl::init(false),
131 cl::desc("Disable branch optimizations in CodeGenPrepare"));
132
133static cl::opt<bool>
134 DisableGCOpts("disable-cgp-gc-opts", cl::Hidden, cl::init(false),
135 cl::desc("Disable GC optimizations in CodeGenPrepare"));
136
137static cl::opt<bool> DisableSelectToBranch(
138 "disable-cgp-select2branch", cl::Hidden, cl::init(false),
139 cl::desc("Disable select to branch conversion."));
140
141static cl::opt<bool> AddrSinkUsingGEPs(
142 "addr-sink-using-gep", cl::Hidden, cl::init(true),
143 cl::desc("Address sinking in CGP using GEPs."));
144
145static cl::opt<bool> EnableAndCmpSinking(
146 "enable-andcmp-sinking", cl::Hidden, cl::init(true),
147 cl::desc("Enable sinkinig and/cmp into branches."));
148
149static cl::opt<bool> DisableStoreExtract(
150 "disable-cgp-store-extract", cl::Hidden, cl::init(false),
151 cl::desc("Disable store(extract) optimizations in CodeGenPrepare"));
152
153static cl::opt<bool> StressStoreExtract(
154 "stress-cgp-store-extract", cl::Hidden, cl::init(false),
155 cl::desc("Stress test store(extract) optimizations in CodeGenPrepare"));
156
157static cl::opt<bool> DisableExtLdPromotion(
158 "disable-cgp-ext-ld-promotion", cl::Hidden, cl::init(false),
159 cl::desc("Disable ext(promotable(ld)) -> promoted(ext(ld)) optimization in "
160 "CodeGenPrepare"));
161
162static cl::opt<bool> StressExtLdPromotion(
163 "stress-cgp-ext-ld-promotion", cl::Hidden, cl::init(false),
164 cl::desc("Stress test ext(promotable(ld)) -> promoted(ext(ld)) "
165 "optimization in CodeGenPrepare"));
166
167static cl::opt<bool> DisablePreheaderProtect(
168 "disable-preheader-prot", cl::Hidden, cl::init(false),
169 cl::desc("Disable protection against removing loop preheaders"));
170
171static cl::opt<bool> ProfileGuidedSectionPrefix(
172 "profile-guided-section-prefix", cl::Hidden, cl::init(true), cl::ZeroOrMore,
173 cl::desc("Use profile info to add section prefix for hot/cold functions"));
174
175static cl::opt<unsigned> FreqRatioToSkipMerge(
176 "cgp-freq-ratio-to-skip-merge", cl::Hidden, cl::init(2),
177 cl::desc("Skip merging empty blocks if (frequency of empty block) / "
178 "(frequency of destination block) is greater than this ratio"));
179
180static cl::opt<bool> ForceSplitStore(
181 "force-split-store", cl::Hidden, cl::init(false),
182 cl::desc("Force store splitting no matter what the target query says."));
183
184static cl::opt<bool>
185EnableTypePromotionMerge("cgp-type-promotion-merge", cl::Hidden,
186 cl::desc("Enable merging of redundant sexts when one is dominating"
187 " the other."), cl::init(true));
188
189static cl::opt<bool> DisableComplexAddrModes(
190 "disable-complex-addr-modes", cl::Hidden, cl::init(false),
191 cl::desc("Disables combining addressing modes with different parts "
192 "in optimizeMemoryInst."));
193
194static cl::opt<bool>
195AddrSinkNewPhis("addr-sink-new-phis", cl::Hidden, cl::init(false),
196 cl::desc("Allow creation of Phis in Address sinking."));
197
198static cl::opt<bool>
199AddrSinkNewSelects("addr-sink-new-select", cl::Hidden, cl::init(true),
200 cl::desc("Allow creation of selects in Address sinking."));
201
202static cl::opt<bool> AddrSinkCombineBaseReg(
203 "addr-sink-combine-base-reg", cl::Hidden, cl::init(true),
204 cl::desc("Allow combining of BaseReg field in Address sinking."));
205
206static cl::opt<bool> AddrSinkCombineBaseGV(
207 "addr-sink-combine-base-gv", cl::Hidden, cl::init(true),
208 cl::desc("Allow combining of BaseGV field in Address sinking."));
209
210static cl::opt<bool> AddrSinkCombineBaseOffs(
211 "addr-sink-combine-base-offs", cl::Hidden, cl::init(true),
212 cl::desc("Allow combining of BaseOffs field in Address sinking."));
213
214static cl::opt<bool> AddrSinkCombineScaledReg(
215 "addr-sink-combine-scaled-reg", cl::Hidden, cl::init(true),
216 cl::desc("Allow combining of ScaledReg field in Address sinking."));
217
218namespace {
219
220using SetOfInstrs = SmallPtrSet<Instruction *, 16>;
221using TypeIsSExt = PointerIntPair<Type *, 1, bool>;
222using InstrToOrigTy = DenseMap<Instruction *, TypeIsSExt>;
223using SExts = SmallVector<Instruction *, 16>;
224using ValueToSExts = DenseMap<Value *, SExts>;
225
226class TypePromotionTransaction;
227
228 class CodeGenPrepare : public FunctionPass {
229 const TargetMachine *TM = nullptr;
230 const TargetSubtargetInfo *SubtargetInfo;
231 const TargetLowering *TLI = nullptr;
232 const TargetRegisterInfo *TRI;
233 const TargetTransformInfo *TTI = nullptr;
234 const TargetLibraryInfo *TLInfo;
235 const LoopInfo *LI;
236 std::unique_ptr<BlockFrequencyInfo> BFI;
237 std::unique_ptr<BranchProbabilityInfo> BPI;
238
239 /// As we scan instructions optimizing them, this is the next instruction
240 /// to optimize. Transforms that can invalidate this should update it.
241 BasicBlock::iterator CurInstIterator;
242
243 /// Keeps track of non-local addresses that have been sunk into a block.
244 /// This allows us to avoid inserting duplicate code for blocks with
245 /// multiple load/stores of the same address. The usage of WeakTrackingVH
246 /// enables SunkAddrs to be treated as a cache whose entries can be
247 /// invalidated if a sunken address computation has been erased.
248 ValueMap<Value*, WeakTrackingVH> SunkAddrs;
249
250 /// Keeps track of all instructions inserted for the current function.
251 SetOfInstrs InsertedInsts;
252
253 /// Keeps track of the type of the related instruction before their
254 /// promotion for the current function.
255 InstrToOrigTy PromotedInsts;
256
257 /// Keep track of instructions removed during promotion.
258 SetOfInstrs RemovedInsts;
259
260 /// Keep track of sext chains based on their initial value.
261 DenseMap<Value *, Instruction *> SeenChainsForSExt;
262
263 /// Keep track of SExt promoted.
264 ValueToSExts ValToSExtendedUses;
265
266 /// True if CFG is modified in any way.
267 bool ModifiedDT;
268
269 /// True if optimizing for size.
270 bool OptSize;
271
272 /// DataLayout for the Function being processed.
273 const DataLayout *DL = nullptr;
274
275 public:
276 static char ID; // Pass identification, replacement for typeid
277
278 CodeGenPrepare() : FunctionPass(ID) {
279 initializeCodeGenPreparePass(*PassRegistry::getPassRegistry());
280 }
281
282 bool runOnFunction(Function &F) override;
283
284 StringRef getPassName() const override { return "CodeGen Prepare"; }
285
286 void getAnalysisUsage(AnalysisUsage &AU) const override {
287 // FIXME: When we can selectively preserve passes, preserve the domtree.
288 AU.addRequired<ProfileSummaryInfoWrapperPass>();
289 AU.addRequired<TargetLibraryInfoWrapperPass>();
290 AU.addRequired<TargetTransformInfoWrapperPass>();
291 AU.addRequired<LoopInfoWrapperPass>();
292 }
293
294 private:
295 bool eliminateFallThrough(Function &F);
296 bool eliminateMostlyEmptyBlocks(Function &F);
297 BasicBlock *findDestBlockOfMergeableEmptyBlock(BasicBlock *BB);
298 bool canMergeBlocks(const BasicBlock *BB, const BasicBlock *DestBB) const;
299 void eliminateMostlyEmptyBlock(BasicBlock *BB);
300 bool isMergingEmptyBlockProfitable(BasicBlock *BB, BasicBlock *DestBB,
301 bool isPreheader);
302 bool optimizeBlock(BasicBlock &BB, bool &ModifiedDT);
303 bool optimizeInst(Instruction *I, bool &ModifiedDT);
304 bool optimizeMemoryInst(Instruction *I, Value *Addr,
305 Type *AccessTy, unsigned AS);
306 bool optimizeInlineAsmInst(CallInst *CS);
307 bool optimizeCallInst(CallInst *CI, bool &ModifiedDT);
308 bool optimizeExt(Instruction *&I);
309 bool optimizeExtUses(Instruction *I);
310 bool optimizeLoadExt(LoadInst *I);
311 bool optimizeSelectInst(SelectInst *SI);
312 bool optimizeShuffleVectorInst(ShuffleVectorInst *SI);
313 bool optimizeSwitchInst(SwitchInst *CI);
314 bool optimizeExtractElementInst(Instruction *Inst);
315 bool dupRetToEnableTailCallOpts(BasicBlock *BB);
316 bool placeDbgValues(Function &F);
317 bool canFormExtLd(const SmallVectorImpl<Instruction *> &MovedExts,
318 LoadInst *&LI, Instruction *&Inst, bool HasPromoted);
319 bool tryToPromoteExts(TypePromotionTransaction &TPT,
320 const SmallVectorImpl<Instruction *> &Exts,
321 SmallVectorImpl<Instruction *> &ProfitablyMovedExts,
322 unsigned CreatedInstsCost = 0);
323 bool mergeSExts(Function &F);
324 bool performAddressTypePromotion(
325 Instruction *&Inst,
326 bool AllowPromotionWithoutCommonHeader,
327 bool HasPromoted, TypePromotionTransaction &TPT,
328 SmallVectorImpl<Instruction *> &SpeculativelyMovedExts);
329 bool splitBranchCondition(Function &F);
330 bool simplifyOffsetableRelocate(Instruction &I);
331 };
332
333} // end anonymous namespace
334
335char CodeGenPrepare::ID = 0;
336
337INITIALIZE_PASS_BEGIN(CodeGenPrepare, DEBUG_TYPE,static void *initializeCodeGenPreparePassOnce(PassRegistry &
Registry) {
338 "Optimize for code generation", false, false)static void *initializeCodeGenPreparePassOnce(PassRegistry &
Registry) {
339INITIALIZE_PASS_DEPENDENCY(ProfileSummaryInfoWrapperPass)initializeProfileSummaryInfoWrapperPassPass(Registry);
340INITIALIZE_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)); }
341 "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)); }
342
343FunctionPass *llvm::createCodeGenPreparePass() { return new CodeGenPrepare(); }
344
345bool CodeGenPrepare::runOnFunction(Function &F) {
346 if (skipFunction(F))
1
Assuming the condition is false
2
Taking false branch
347 return false;
348
349 DL = &F.getParent()->getDataLayout();
350
351 bool EverMadeChange = false;
352 // Clear per function information.
353 InsertedInsts.clear();
354 PromotedInsts.clear();
355
356 ModifiedDT = false;
357 if (auto *TPC = getAnalysisIfAvailable<TargetPassConfig>()) {
3
Assuming 'TPC' is null
4
Taking false branch
358 TM = &TPC->getTM<TargetMachine>();
359 SubtargetInfo = TM->getSubtargetImpl(F);
360 TLI = SubtargetInfo->getTargetLowering();
361 TRI = SubtargetInfo->getRegisterInfo();
362 }
363 TLInfo = &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
364 TTI = &getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
365 LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
366 BPI.reset(new BranchProbabilityInfo(F, *LI));
367 BFI.reset(new BlockFrequencyInfo(F, *BPI, *LI));
368 OptSize = F.optForSize();
369
370 ProfileSummaryInfo *PSI =
371 getAnalysis<ProfileSummaryInfoWrapperPass>().getPSI();
372 if (ProfileGuidedSectionPrefix) {
5
Assuming the condition is false
6
Taking false branch
373 if (PSI->isFunctionHotInCallGraph(&F, *BFI))
374 F.setSectionPrefix(".hot");
375 else if (PSI->isFunctionColdInCallGraph(&F, *BFI))
376 F.setSectionPrefix(".unlikely");
377 }
378
379 /// This optimization identifies DIV instructions that can be
380 /// profitably bypassed and carried out with a shorter, faster divide.
381 if (!OptSize && !PSI->hasHugeWorkingSetSize() && TLI &&
7
Assuming the condition is false
382 TLI->isSlowDivBypassed()) {
383 const DenseMap<unsigned int, unsigned int> &BypassWidths =
384 TLI->getBypassSlowDivWidths();
385 BasicBlock* BB = &*F.begin();
386 while (BB != nullptr) {
387 // bypassSlowDivision may create new BBs, but we don't want to reapply the
388 // optimization to those blocks.
389 BasicBlock* Next = BB->getNextNode();
390 EverMadeChange |= bypassSlowDivision(BB, BypassWidths);
391 BB = Next;
392 }
393 }
394
395 // Eliminate blocks that contain only PHI nodes and an
396 // unconditional branch.
397 EverMadeChange |= eliminateMostlyEmptyBlocks(F);
398
399 // llvm.dbg.value is far away from the value then iSel may not be able
400 // handle it properly. iSel will drop llvm.dbg.value if it can not
401 // find a node corresponding to the value.
402 EverMadeChange |= placeDbgValues(F);
403
404 if (!DisableBranchOpts)
8
Assuming the condition is false
9
Taking false branch
405 EverMadeChange |= splitBranchCondition(F);
406
407 // Split some critical edges where one of the sources is an indirect branch,
408 // to help generate sane code for PHIs involving such edges.
409 EverMadeChange |= SplitIndirectBrCriticalEdges(F);
410
411 bool MadeChange = true;
412 while (MadeChange) {
10
Loop condition is true. Entering loop body
13
Loop condition is false. Execution continues on line 436
413 MadeChange = false;
414 SeenChainsForSExt.clear();
415 ValToSExtendedUses.clear();
416 RemovedInsts.clear();
417 for (Function::iterator I = F.begin(); I != F.end(); ) {
11
Loop condition is false. Execution continues on line 426
418 BasicBlock *BB = &*I++;
419 bool ModifiedDTOnIteration = false;
420 MadeChange |= optimizeBlock(*BB, ModifiedDTOnIteration);
421
422 // Restart BB iteration if the dominator tree of the Function was changed
423 if (ModifiedDTOnIteration)
424 break;
425 }
426 if (EnableTypePromotionMerge && !ValToSExtendedUses.empty())
12
Assuming the condition is false
427 MadeChange |= mergeSExts(F);
428
429 // Really free removed instructions during promotion.
430 for (Instruction *I : RemovedInsts)
431 I->deleteValue();
432
433 EverMadeChange |= MadeChange;
434 }
435
436 SunkAddrs.clear();
437
438 if (!DisableBranchOpts) {
14
Assuming the condition is false
15
Taking false branch
439 MadeChange = false;
440 SmallPtrSet<BasicBlock*, 8> WorkList;
441 for (BasicBlock &BB : F) {
442 SmallVector<BasicBlock *, 2> Successors(succ_begin(&BB), succ_end(&BB));
443 MadeChange |= ConstantFoldTerminator(&BB, true);
444 if (!MadeChange) continue;
445
446 for (SmallVectorImpl<BasicBlock*>::iterator
447 II = Successors.begin(), IE = Successors.end(); II != IE; ++II)
448 if (pred_begin(*II) == pred_end(*II))
449 WorkList.insert(*II);
450 }
451
452 // Delete the dead blocks and any of their dead successors.
453 MadeChange |= !WorkList.empty();
454 while (!WorkList.empty()) {
455 BasicBlock *BB = *WorkList.begin();
456 WorkList.erase(BB);
457 SmallVector<BasicBlock*, 2> Successors(succ_begin(BB), succ_end(BB));
458
459 DeleteDeadBlock(BB);
460
461 for (SmallVectorImpl<BasicBlock*>::iterator
462 II = Successors.begin(), IE = Successors.end(); II != IE; ++II)
463 if (pred_begin(*II) == pred_end(*II))
464 WorkList.insert(*II);
465 }
466
467 // Merge pairs of basic blocks with unconditional branches, connected by
468 // a single edge.
469 if (EverMadeChange || MadeChange)
470 MadeChange |= eliminateFallThrough(F);
471
472 EverMadeChange |= MadeChange;
473 }
474
475 if (!DisableGCOpts) {
16
Assuming the condition is true
17
Taking true branch
476 SmallVector<Instruction *, 2> Statepoints;
477 for (BasicBlock &BB : F)
478 for (Instruction &I : BB)
479 if (isStatepoint(I))
480 Statepoints.push_back(&I);
481 for (auto &I : Statepoints)
18
Assuming '__begin2' is not equal to '__end2'
482 EverMadeChange |= simplifyOffsetableRelocate(*I);
19
Calling 'CodeGenPrepare::simplifyOffsetableRelocate'
483 }
484
485 return EverMadeChange;
486}
487
488/// Merge basic blocks which are connected by a single edge, where one of the
489/// basic blocks has a single successor pointing to the other basic block,
490/// which has a single predecessor.
491bool CodeGenPrepare::eliminateFallThrough(Function &F) {
492 bool Changed = false;
493 // Scan all of the blocks in the function, except for the entry block.
494 for (Function::iterator I = std::next(F.begin()), E = F.end(); I != E;) {
495 BasicBlock *BB = &*I++;
496 // If the destination block has a single pred, then this is a trivial
497 // edge, just collapse it.
498 BasicBlock *SinglePred = BB->getSinglePredecessor();
499
500 // Don't merge if BB's address is taken.
501 if (!SinglePred || SinglePred == BB || BB->hasAddressTaken()) continue;
502
503 BranchInst *Term = dyn_cast<BranchInst>(SinglePred->getTerminator());
504 if (Term && !Term->isConditional()) {
505 Changed = true;
506 DEBUG(dbgs() << "To merge:\n"<< *SinglePred << "\n\n\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "To merge:\n"<< *
SinglePred << "\n\n\n"; } } while (false)
;
507 // Remember if SinglePred was the entry block of the function.
508 // If so, we will need to move BB back to the entry position.
509 bool isEntry = SinglePred == &SinglePred->getParent()->getEntryBlock();
510 MergeBasicBlockIntoOnlyPred(BB, nullptr);
511
512 if (isEntry && BB != &BB->getParent()->getEntryBlock())
513 BB->moveBefore(&BB->getParent()->getEntryBlock());
514
515 // We have erased a block. Update the iterator.
516 I = BB->getIterator();
517 }
518 }
519 return Changed;
520}
521
522/// Find a destination block from BB if BB is mergeable empty block.
523BasicBlock *CodeGenPrepare::findDestBlockOfMergeableEmptyBlock(BasicBlock *BB) {
524 // If this block doesn't end with an uncond branch, ignore it.
525 BranchInst *BI = dyn_cast<BranchInst>(BB->getTerminator());
526 if (!BI || !BI->isUnconditional())
527 return nullptr;
528
529 // If the instruction before the branch (skipping debug info) isn't a phi
530 // node, then other stuff is happening here.
531 BasicBlock::iterator BBI = BI->getIterator();
532 if (BBI != BB->begin()) {
533 --BBI;
534 while (isa<DbgInfoIntrinsic>(BBI)) {
535 if (BBI == BB->begin())
536 break;
537 --BBI;
538 }
539 if (!isa<DbgInfoIntrinsic>(BBI) && !isa<PHINode>(BBI))
540 return nullptr;
541 }
542
543 // Do not break infinite loops.
544 BasicBlock *DestBB = BI->getSuccessor(0);
545 if (DestBB == BB)
546 return nullptr;
547
548 if (!canMergeBlocks(BB, DestBB))
549 DestBB = nullptr;
550
551 return DestBB;
552}
553
554/// Eliminate blocks that contain only PHI nodes, debug info directives, and an
555/// unconditional branch. Passes before isel (e.g. LSR/loopsimplify) often split
556/// edges in ways that are non-optimal for isel. Start by eliminating these
557/// blocks so we can split them the way we want them.
558bool CodeGenPrepare::eliminateMostlyEmptyBlocks(Function &F) {
559 SmallPtrSet<BasicBlock *, 16> Preheaders;
560 SmallVector<Loop *, 16> LoopList(LI->begin(), LI->end());
561 while (!LoopList.empty()) {
562 Loop *L = LoopList.pop_back_val();
563 LoopList.insert(LoopList.end(), L->begin(), L->end());
564 if (BasicBlock *Preheader = L->getLoopPreheader())
565 Preheaders.insert(Preheader);
566 }
567
568 bool MadeChange = false;
569 // Note that this intentionally skips the entry block.
570 for (Function::iterator I = std::next(F.begin()), E = F.end(); I != E;) {
571 BasicBlock *BB = &*I++;
572 BasicBlock *DestBB = findDestBlockOfMergeableEmptyBlock(BB);
573 if (!DestBB ||
574 !isMergingEmptyBlockProfitable(BB, DestBB, Preheaders.count(BB)))
575 continue;
576
577 eliminateMostlyEmptyBlock(BB);
578 MadeChange = true;
579 }
580 return MadeChange;
581}
582
583bool CodeGenPrepare::isMergingEmptyBlockProfitable(BasicBlock *BB,
584 BasicBlock *DestBB,
585 bool isPreheader) {
586 // Do not delete loop preheaders if doing so would create a critical edge.
587 // Loop preheaders can be good locations to spill registers. If the
588 // preheader is deleted and we create a critical edge, registers may be
589 // spilled in the loop body instead.
590 if (!DisablePreheaderProtect && isPreheader &&
591 !(BB->getSinglePredecessor() &&
592 BB->getSinglePredecessor()->getSingleSuccessor()))
593 return false;
594
595 // Try to skip merging if the unique predecessor of BB is terminated by a
596 // switch or indirect branch instruction, and BB is used as an incoming block
597 // of PHIs in DestBB. In such case, merging BB and DestBB would cause ISel to
598 // add COPY instructions in the predecessor of BB instead of BB (if it is not
599 // merged). Note that the critical edge created by merging such blocks wont be
600 // split in MachineSink because the jump table is not analyzable. By keeping
601 // such empty block (BB), ISel will place COPY instructions in BB, not in the
602 // predecessor of BB.
603 BasicBlock *Pred = BB->getUniquePredecessor();
604 if (!Pred ||
605 !(isa<SwitchInst>(Pred->getTerminator()) ||
606 isa<IndirectBrInst>(Pred->getTerminator())))
607 return true;
608
609 if (BB->getTerminator() != BB->getFirstNonPHI())
610 return true;
611
612 // We use a simple cost heuristic which determine skipping merging is
613 // profitable if the cost of skipping merging is less than the cost of
614 // merging : Cost(skipping merging) < Cost(merging BB), where the
615 // Cost(skipping merging) is Freq(BB) * (Cost(Copy) + Cost(Branch)), and
616 // the Cost(merging BB) is Freq(Pred) * Cost(Copy).
617 // Assuming Cost(Copy) == Cost(Branch), we could simplify it to :
618 // Freq(Pred) / Freq(BB) > 2.
619 // Note that if there are multiple empty blocks sharing the same incoming
620 // value for the PHIs in the DestBB, we consider them together. In such
621 // case, Cost(merging BB) will be the sum of their frequencies.
622
623 if (!isa<PHINode>(DestBB->begin()))
624 return true;
625
626 SmallPtrSet<BasicBlock *, 16> SameIncomingValueBBs;
627
628 // Find all other incoming blocks from which incoming values of all PHIs in
629 // DestBB are the same as the ones from BB.
630 for (pred_iterator PI = pred_begin(DestBB), E = pred_end(DestBB); PI != E;
631 ++PI) {
632 BasicBlock *DestBBPred = *PI;
633 if (DestBBPred == BB)
634 continue;
635
636 if (llvm::all_of(DestBB->phis(), [&](const PHINode &DestPN) {
637 return DestPN.getIncomingValueForBlock(BB) ==
638 DestPN.getIncomingValueForBlock(DestBBPred);
639 }))
640 SameIncomingValueBBs.insert(DestBBPred);
641 }
642
643 // See if all BB's incoming values are same as the value from Pred. In this
644 // case, no reason to skip merging because COPYs are expected to be place in
645 // Pred already.
646 if (SameIncomingValueBBs.count(Pred))
647 return true;
648
649 BlockFrequency PredFreq = BFI->getBlockFreq(Pred);
650 BlockFrequency BBFreq = BFI->getBlockFreq(BB);
651
652 for (auto SameValueBB : SameIncomingValueBBs)
653 if (SameValueBB->getUniquePredecessor() == Pred &&
654 DestBB == findDestBlockOfMergeableEmptyBlock(SameValueBB))
655 BBFreq += BFI->getBlockFreq(SameValueBB);
656
657 return PredFreq.getFrequency() <=
658 BBFreq.getFrequency() * FreqRatioToSkipMerge;
659}
660
661/// Return true if we can merge BB into DestBB if there is a single
662/// unconditional branch between them, and BB contains no other non-phi
663/// instructions.
664bool CodeGenPrepare::canMergeBlocks(const BasicBlock *BB,
665 const BasicBlock *DestBB) const {
666 // We only want to eliminate blocks whose phi nodes are used by phi nodes in
667 // the successor. If there are more complex condition (e.g. preheaders),
668 // don't mess around with them.
669 for (const PHINode &PN : BB->phis()) {
670 for (const User *U : PN.users()) {
671 const Instruction *UI = cast<Instruction>(U);
672 if (UI->getParent() != DestBB || !isa<PHINode>(UI))
673 return false;
674 // If User is inside DestBB block and it is a PHINode then check
675 // incoming value. If incoming value is not from BB then this is
676 // a complex condition (e.g. preheaders) we want to avoid here.
677 if (UI->getParent() == DestBB) {
678 if (const PHINode *UPN = dyn_cast<PHINode>(UI))
679 for (unsigned I = 0, E = UPN->getNumIncomingValues(); I != E; ++I) {
680 Instruction *Insn = dyn_cast<Instruction>(UPN->getIncomingValue(I));
681 if (Insn && Insn->getParent() == BB &&
682 Insn->getParent() != UPN->getIncomingBlock(I))
683 return false;
684 }
685 }
686 }
687 }
688
689 // If BB and DestBB contain any common predecessors, then the phi nodes in BB
690 // and DestBB may have conflicting incoming values for the block. If so, we
691 // can't merge the block.
692 const PHINode *DestBBPN = dyn_cast<PHINode>(DestBB->begin());
693 if (!DestBBPN) return true; // no conflict.
694
695 // Collect the preds of BB.
696 SmallPtrSet<const BasicBlock*, 16> BBPreds;
697 if (const PHINode *BBPN = dyn_cast<PHINode>(BB->begin())) {
698 // It is faster to get preds from a PHI than with pred_iterator.
699 for (unsigned i = 0, e = BBPN->getNumIncomingValues(); i != e; ++i)
700 BBPreds.insert(BBPN->getIncomingBlock(i));
701 } else {
702 BBPreds.insert(pred_begin(BB), pred_end(BB));
703 }
704
705 // Walk the preds of DestBB.
706 for (unsigned i = 0, e = DestBBPN->getNumIncomingValues(); i != e; ++i) {
707 BasicBlock *Pred = DestBBPN->getIncomingBlock(i);
708 if (BBPreds.count(Pred)) { // Common predecessor?
709 for (const PHINode &PN : DestBB->phis()) {
710 const Value *V1 = PN.getIncomingValueForBlock(Pred);
711 const Value *V2 = PN.getIncomingValueForBlock(BB);
712
713 // If V2 is a phi node in BB, look up what the mapped value will be.
714 if (const PHINode *V2PN = dyn_cast<PHINode>(V2))
715 if (V2PN->getParent() == BB)
716 V2 = V2PN->getIncomingValueForBlock(Pred);
717
718 // If there is a conflict, bail out.
719 if (V1 != V2) return false;
720 }
721 }
722 }
723
724 return true;
725}
726
727/// Eliminate a basic block that has only phi's and an unconditional branch in
728/// it.
729void CodeGenPrepare::eliminateMostlyEmptyBlock(BasicBlock *BB) {
730 BranchInst *BI = cast<BranchInst>(BB->getTerminator());
731 BasicBlock *DestBB = BI->getSuccessor(0);
732
733 DEBUG(dbgs() << "MERGING MOSTLY EMPTY BLOCKS - BEFORE:\n" << *BB << *DestBB)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "MERGING MOSTLY EMPTY BLOCKS - BEFORE:\n"
<< *BB << *DestBB; } } while (false)
;
734
735 // If the destination block has a single pred, then this is a trivial edge,
736 // just collapse it.
737 if (BasicBlock *SinglePred = DestBB->getSinglePredecessor()) {
738 if (SinglePred != DestBB) {
739 // Remember if SinglePred was the entry block of the function. If so, we
740 // will need to move BB back to the entry position.
741 bool isEntry = SinglePred == &SinglePred->getParent()->getEntryBlock();
742 MergeBasicBlockIntoOnlyPred(DestBB, nullptr);
743
744 if (isEntry && BB != &BB->getParent()->getEntryBlock())
745 BB->moveBefore(&BB->getParent()->getEntryBlock());
746
747 DEBUG(dbgs() << "AFTER:\n" << *DestBB << "\n\n\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "AFTER:\n" << *DestBB
<< "\n\n\n"; } } while (false)
;
748 return;
749 }
750 }
751
752 // Otherwise, we have multiple predecessors of BB. Update the PHIs in DestBB
753 // to handle the new incoming edges it is about to have.
754 for (PHINode &PN : DestBB->phis()) {
755 // Remove the incoming value for BB, and remember it.
756 Value *InVal = PN.removeIncomingValue(BB, false);
757
758 // Two options: either the InVal is a phi node defined in BB or it is some
759 // value that dominates BB.
760 PHINode *InValPhi = dyn_cast<PHINode>(InVal);
761 if (InValPhi && InValPhi->getParent() == BB) {
762 // Add all of the input values of the input PHI as inputs of this phi.
763 for (unsigned i = 0, e = InValPhi->getNumIncomingValues(); i != e; ++i)
764 PN.addIncoming(InValPhi->getIncomingValue(i),
765 InValPhi->getIncomingBlock(i));
766 } else {
767 // Otherwise, add one instance of the dominating value for each edge that
768 // we will be adding.
769 if (PHINode *BBPN = dyn_cast<PHINode>(BB->begin())) {
770 for (unsigned i = 0, e = BBPN->getNumIncomingValues(); i != e; ++i)
771 PN.addIncoming(InVal, BBPN->getIncomingBlock(i));
772 } else {
773 for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI)
774 PN.addIncoming(InVal, *PI);
775 }
776 }
777 }
778
779 // The PHIs are now updated, change everything that refers to BB to use
780 // DestBB and remove BB.
781 BB->replaceAllUsesWith(DestBB);
782 BB->eraseFromParent();
783 ++NumBlocksElim;
784
785 DEBUG(dbgs() << "AFTER:\n" << *DestBB << "\n\n\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "AFTER:\n" << *DestBB
<< "\n\n\n"; } } while (false)
;
786}
787
788// Computes a map of base pointer relocation instructions to corresponding
789// derived pointer relocation instructions given a vector of all relocate calls
790static void computeBaseDerivedRelocateMap(
791 const SmallVectorImpl<GCRelocateInst *> &AllRelocateCalls,
792 DenseMap<GCRelocateInst *, SmallVector<GCRelocateInst *, 2>>
793 &RelocateInstMap) {
794 // Collect information in two maps: one primarily for locating the base object
795 // while filling the second map; the second map is the final structure holding
796 // a mapping between Base and corresponding Derived relocate calls
797 DenseMap<std::pair<unsigned, unsigned>, GCRelocateInst *> RelocateIdxMap;
798 for (auto *ThisRelocate : AllRelocateCalls) {
799 auto K = std::make_pair(ThisRelocate->getBasePtrIndex(),
800 ThisRelocate->getDerivedPtrIndex());
801 RelocateIdxMap.insert(std::make_pair(K, ThisRelocate));
802 }
803 for (auto &Item : RelocateIdxMap) {
804 std::pair<unsigned, unsigned> Key = Item.first;
805 if (Key.first == Key.second)
806 // Base relocation: nothing to insert
807 continue;
808
809 GCRelocateInst *I = Item.second;
810 auto BaseKey = std::make_pair(Key.first, Key.first);
811
812 // We're iterating over RelocateIdxMap so we cannot modify it.
813 auto MaybeBase = RelocateIdxMap.find(BaseKey);
814 if (MaybeBase == RelocateIdxMap.end())
815 // TODO: We might want to insert a new base object relocate and gep off
816 // that, if there are enough derived object relocates.
817 continue;
818
819 RelocateInstMap[MaybeBase->second].push_back(I);
820 }
821}
822
823// Accepts a GEP and extracts the operands into a vector provided they're all
824// small integer constants
825static bool getGEPSmallConstantIntOffsetV(GetElementPtrInst *GEP,
826 SmallVectorImpl<Value *> &OffsetV) {
827 for (unsigned i = 1; i < GEP->getNumOperands(); i++) {
828 // Only accept small constant integer operands
829 auto Op = dyn_cast<ConstantInt>(GEP->getOperand(i));
830 if (!Op || Op->getZExtValue() > 20)
831 return false;
832 }
833
834 for (unsigned i = 1; i < GEP->getNumOperands(); i++)
835 OffsetV.push_back(GEP->getOperand(i));
836 return true;
837}
838
839// Takes a RelocatedBase (base pointer relocation instruction) and Targets to
840// replace, computes a replacement, and affects it.
841static bool
842simplifyRelocatesOffABase(GCRelocateInst *RelocatedBase,
843 const SmallVectorImpl<GCRelocateInst *> &Targets) {
844 bool MadeChange = false;
845 // We must ensure the relocation of derived pointer is defined after
846 // relocation of base pointer. If we find a relocation corresponding to base
847 // defined earlier than relocation of base then we move relocation of base
848 // right before found relocation. We consider only relocation in the same
849 // basic block as relocation of base. Relocations from other basic block will
850 // be skipped by optimization and we do not care about them.
851 for (auto R = RelocatedBase->getParent()->getFirstInsertionPt();
26
Loop condition is false. Execution continues on line 860
852 &*R != RelocatedBase; ++R)
25
Assuming the condition is false
853 if (auto RI = dyn_cast<GCRelocateInst>(R))
854 if (RI->getStatepoint() == RelocatedBase->getStatepoint())
855 if (RI->getBasePtrIndex() == RelocatedBase->getBasePtrIndex()) {
856 RelocatedBase->moveBefore(RI);
857 break;
858 }
859
860 for (GCRelocateInst *ToReplace : Targets) {
27
Assuming '__begin1' is not equal to '__end1'
861 assert(ToReplace->getBasePtrIndex() == RelocatedBase->getBasePtrIndex() &&(static_cast <bool> (ToReplace->getBasePtrIndex() ==
RelocatedBase->getBasePtrIndex() && "Not relocating a derived object of the original base object"
) ? void (0) : __assert_fail ("ToReplace->getBasePtrIndex() == RelocatedBase->getBasePtrIndex() && \"Not relocating a derived object of the original base object\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 862, __extension__ __PRETTY_FUNCTION__))
862 "Not relocating a derived object of the original base object")(static_cast <bool> (ToReplace->getBasePtrIndex() ==
RelocatedBase->getBasePtrIndex() && "Not relocating a derived object of the original base object"
) ? void (0) : __assert_fail ("ToReplace->getBasePtrIndex() == RelocatedBase->getBasePtrIndex() && \"Not relocating a derived object of the original base object\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 862, __extension__ __PRETTY_FUNCTION__))
;
863 if (ToReplace->getBasePtrIndex() == ToReplace->getDerivedPtrIndex()) {
28
Taking false branch
864 // A duplicate relocate call. TODO: coalesce duplicates.
865 continue;
866 }
867
868 if (RelocatedBase->getParent() != ToReplace->getParent()) {
29
Assuming the condition is false
30
Taking false branch
869 // Base and derived relocates are in different basic blocks.
870 // In this case transform is only valid when base dominates derived
871 // relocate. However it would be too expensive to check dominance
872 // for each such relocate, so we skip the whole transformation.
873 continue;
874 }
875
876 Value *Base = ToReplace->getBasePtr();
31
Calling 'GCRelocateInst::getBasePtr'
34
Returning from 'GCRelocateInst::getBasePtr'
35
'Base' initialized here
877 auto Derived = dyn_cast<GetElementPtrInst>(ToReplace->getDerivedPtr());
878 if (!Derived || Derived->getPointerOperand() != Base)
36
Assuming 'Derived' is non-null
37
Assuming pointer value is null
38
Taking false branch
879 continue;
880
881 SmallVector<Value *, 2> OffsetV;
882 if (!getGEPSmallConstantIntOffsetV(Derived, OffsetV))
39
Taking false branch
883 continue;
884
885 // Create a Builder and replace the target callsite with a gep
886 assert(RelocatedBase->getNextNode() &&(static_cast <bool> (RelocatedBase->getNextNode() &&
"Should always have one since it's not a terminator") ? void
(0) : __assert_fail ("RelocatedBase->getNextNode() && \"Should always have one since it's not a terminator\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 887, __extension__ __PRETTY_FUNCTION__))
887 "Should always have one since it's not a terminator")(static_cast <bool> (RelocatedBase->getNextNode() &&
"Should always have one since it's not a terminator") ? void
(0) : __assert_fail ("RelocatedBase->getNextNode() && \"Should always have one since it's not a terminator\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 887, __extension__ __PRETTY_FUNCTION__))
;
888
889 // Insert after RelocatedBase
890 IRBuilder<> Builder(RelocatedBase->getNextNode());
891 Builder.SetCurrentDebugLocation(ToReplace->getDebugLoc());
892
893 // If gc_relocate does not match the actual type, cast it to the right type.
894 // In theory, there must be a bitcast after gc_relocate if the type does not
895 // match, and we should reuse it to get the derived pointer. But it could be
896 // cases like this:
897 // bb1:
898 // ...
899 // %g1 = call coldcc i8 addrspace(1)* @llvm.experimental.gc.relocate.p1i8(...)
900 // br label %merge
901 //
902 // bb2:
903 // ...
904 // %g2 = call coldcc i8 addrspace(1)* @llvm.experimental.gc.relocate.p1i8(...)
905 // br label %merge
906 //
907 // merge:
908 // %p1 = phi i8 addrspace(1)* [ %g1, %bb1 ], [ %g2, %bb2 ]
909 // %cast = bitcast i8 addrspace(1)* %p1 in to i32 addrspace(1)*
910 //
911 // In this case, we can not find the bitcast any more. So we insert a new bitcast
912 // no matter there is already one or not. In this way, we can handle all cases, and
913 // the extra bitcast should be optimized away in later passes.
914 Value *ActualRelocatedBase = RelocatedBase;
915 if (RelocatedBase->getType() != Base->getType()) {
40
Called C++ object pointer is null
916 ActualRelocatedBase =
917 Builder.CreateBitCast(RelocatedBase, Base->getType());
918 }
919 Value *Replacement = Builder.CreateGEP(
920 Derived->getSourceElementType(), ActualRelocatedBase, makeArrayRef(OffsetV));
921 Replacement->takeName(ToReplace);
922 // If the newly generated derived pointer's type does not match the original derived
923 // pointer's type, cast the new derived pointer to match it. Same reasoning as above.
924 Value *ActualReplacement = Replacement;
925 if (Replacement->getType() != ToReplace->getType()) {
926 ActualReplacement =
927 Builder.CreateBitCast(Replacement, ToReplace->getType());
928 }
929 ToReplace->replaceAllUsesWith(ActualReplacement);
930 ToReplace->eraseFromParent();
931
932 MadeChange = true;
933 }
934 return MadeChange;
935}
936
937// Turns this:
938//
939// %base = ...
940// %ptr = gep %base + 15
941// %tok = statepoint (%fun, i32 0, i32 0, i32 0, %base, %ptr)
942// %base' = relocate(%tok, i32 4, i32 4)
943// %ptr' = relocate(%tok, i32 4, i32 5)
944// %val = load %ptr'
945//
946// into this:
947//
948// %base = ...
949// %ptr = gep %base + 15
950// %tok = statepoint (%fun, i32 0, i32 0, i32 0, %base, %ptr)
951// %base' = gc.relocate(%tok, i32 4, i32 4)
952// %ptr' = gep %base' + 15
953// %val = load %ptr'
954bool CodeGenPrepare::simplifyOffsetableRelocate(Instruction &I) {
955 bool MadeChange = false;
956 SmallVector<GCRelocateInst *, 2> AllRelocateCalls;
957
958 for (auto *U : I.users())
959 if (GCRelocateInst *Relocate = dyn_cast<GCRelocateInst>(U))
960 // Collect all the relocate calls associated with a statepoint
961 AllRelocateCalls.push_back(Relocate);
962
963 // We need atleast one base pointer relocation + one derived pointer
964 // relocation to mangle
965 if (AllRelocateCalls.size() < 2)
20
Assuming the condition is false
21
Taking false branch
966 return false;
967
968 // RelocateInstMap is a mapping from the base relocate instruction to the
969 // corresponding derived relocate instructions
970 DenseMap<GCRelocateInst *, SmallVector<GCRelocateInst *, 2>> RelocateInstMap;
971 computeBaseDerivedRelocateMap(AllRelocateCalls, RelocateInstMap);
972 if (RelocateInstMap.empty())
22
Assuming the condition is false
23
Taking false branch
973 return false;
974
975 for (auto &Item : RelocateInstMap)
976 // Item.first is the RelocatedBase to offset against
977 // Item.second is the vector of Targets to replace
978 MadeChange = simplifyRelocatesOffABase(Item.first, Item.second);
24
Calling 'simplifyRelocatesOffABase'
979 return MadeChange;
980}
981
982/// SinkCast - Sink the specified cast instruction into its user blocks
983static bool SinkCast(CastInst *CI) {
984 BasicBlock *DefBB = CI->getParent();
985
986 /// InsertedCasts - Only insert a cast in each block once.
987 DenseMap<BasicBlock*, CastInst*> InsertedCasts;
988
989 bool MadeChange = false;
990 for (Value::user_iterator UI = CI->user_begin(), E = CI->user_end();
991 UI != E; ) {
992 Use &TheUse = UI.getUse();
993 Instruction *User = cast<Instruction>(*UI);
994
995 // Figure out which BB this cast is used in. For PHI's this is the
996 // appropriate predecessor block.
997 BasicBlock *UserBB = User->getParent();
998 if (PHINode *PN = dyn_cast<PHINode>(User)) {
999 UserBB = PN->getIncomingBlock(TheUse);
1000 }
1001
1002 // Preincrement use iterator so we don't invalidate it.
1003 ++UI;
1004
1005 // The first insertion point of a block containing an EH pad is after the
1006 // pad. If the pad is the user, we cannot sink the cast past the pad.
1007 if (User->isEHPad())
1008 continue;
1009
1010 // If the block selected to receive the cast is an EH pad that does not
1011 // allow non-PHI instructions before the terminator, we can't sink the
1012 // cast.
1013 if (UserBB->getTerminator()->isEHPad())
1014 continue;
1015
1016 // If this user is in the same block as the cast, don't change the cast.
1017 if (UserBB == DefBB) continue;
1018
1019 // If we have already inserted a cast into this block, use it.
1020 CastInst *&InsertedCast = InsertedCasts[UserBB];
1021
1022 if (!InsertedCast) {
1023 BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
1024 assert(InsertPt != UserBB->end())(static_cast <bool> (InsertPt != UserBB->end()) ? void
(0) : __assert_fail ("InsertPt != UserBB->end()", "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 1024, __extension__ __PRETTY_FUNCTION__))
;
1025 InsertedCast = CastInst::Create(CI->getOpcode(), CI->getOperand(0),
1026 CI->getType(), "", &*InsertPt);
1027 }
1028
1029 // Replace a use of the cast with a use of the new cast.
1030 TheUse = InsertedCast;
1031 MadeChange = true;
1032 ++NumCastUses;
1033 }
1034
1035 // If we removed all uses, nuke the cast.
1036 if (CI->use_empty()) {
1037 salvageDebugInfo(*CI);
1038 CI->eraseFromParent();
1039 MadeChange = true;
1040 }
1041
1042 return MadeChange;
1043}
1044
1045/// If the specified cast instruction is a noop copy (e.g. it's casting from
1046/// one pointer type to another, i32->i8 on PPC), sink it into user blocks to
1047/// reduce the number of virtual registers that must be created and coalesced.
1048///
1049/// Return true if any changes are made.
1050static bool OptimizeNoopCopyExpression(CastInst *CI, const TargetLowering &TLI,
1051 const DataLayout &DL) {
1052 // Sink only "cheap" (or nop) address-space casts. This is a weaker condition
1053 // than sinking only nop casts, but is helpful on some platforms.
1054 if (auto *ASC = dyn_cast<AddrSpaceCastInst>(CI)) {
1055 if (!TLI.isCheapAddrSpaceCast(ASC->getSrcAddressSpace(),
1056 ASC->getDestAddressSpace()))
1057 return false;
1058 }
1059
1060 // If this is a noop copy,
1061 EVT SrcVT = TLI.getValueType(DL, CI->getOperand(0)->getType());
1062 EVT DstVT = TLI.getValueType(DL, CI->getType());
1063
1064 // This is an fp<->int conversion?
1065 if (SrcVT.isInteger() != DstVT.isInteger())
1066 return false;
1067
1068 // If this is an extension, it will be a zero or sign extension, which
1069 // isn't a noop.
1070 if (SrcVT.bitsLT(DstVT)) return false;
1071
1072 // If these values will be promoted, find out what they will be promoted
1073 // to. This helps us consider truncates on PPC as noop copies when they
1074 // are.
1075 if (TLI.getTypeAction(CI->getContext(), SrcVT) ==
1076 TargetLowering::TypePromoteInteger)
1077 SrcVT = TLI.getTypeToTransformTo(CI->getContext(), SrcVT);
1078 if (TLI.getTypeAction(CI->getContext(), DstVT) ==
1079 TargetLowering::TypePromoteInteger)
1080 DstVT = TLI.getTypeToTransformTo(CI->getContext(), DstVT);
1081
1082 // If, after promotion, these are the same types, this is a noop copy.
1083 if (SrcVT != DstVT)
1084 return false;
1085
1086 return SinkCast(CI);
1087}
1088
1089/// Try to combine CI into a call to the llvm.uadd.with.overflow intrinsic if
1090/// possible.
1091///
1092/// Return true if any changes were made.
1093static bool CombineUAddWithOverflow(CmpInst *CI) {
1094 Value *A, *B;
1095 Instruction *AddI;
1096 if (!match(CI,
1097 m_UAddWithOverflow(m_Value(A), m_Value(B), m_Instruction(AddI))))
1098 return false;
1099
1100 Type *Ty = AddI->getType();
1101 if (!isa<IntegerType>(Ty))
1102 return false;
1103
1104 // We don't want to move around uses of condition values this late, so we we
1105 // check if it is legal to create the call to the intrinsic in the basic
1106 // block containing the icmp:
1107
1108 if (AddI->getParent() != CI->getParent() && !AddI->hasOneUse())
1109 return false;
1110
1111#ifndef NDEBUG
1112 // Someday m_UAddWithOverflow may get smarter, but this is a safe assumption
1113 // for now:
1114 if (AddI->hasOneUse())
1115 assert(*AddI->user_begin() == CI && "expected!")(static_cast <bool> (*AddI->user_begin() == CI &&
"expected!") ? void (0) : __assert_fail ("*AddI->user_begin() == CI && \"expected!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 1115, __extension__ __PRETTY_FUNCTION__))
;
1116#endif
1117
1118 Module *M = CI->getModule();
1119 Value *F = Intrinsic::getDeclaration(M, Intrinsic::uadd_with_overflow, Ty);
1120
1121 auto *InsertPt = AddI->hasOneUse() ? CI : AddI;
1122
1123 auto *UAddWithOverflow =
1124 CallInst::Create(F, {A, B}, "uadd.overflow", InsertPt);
1125 auto *UAdd = ExtractValueInst::Create(UAddWithOverflow, 0, "uadd", InsertPt);
1126 auto *Overflow =
1127 ExtractValueInst::Create(UAddWithOverflow, 1, "overflow", InsertPt);
1128
1129 CI->replaceAllUsesWith(Overflow);
1130 AddI->replaceAllUsesWith(UAdd);
1131 CI->eraseFromParent();
1132 AddI->eraseFromParent();
1133 return true;
1134}
1135
1136/// Sink the given CmpInst into user blocks to reduce the number of virtual
1137/// registers that must be created and coalesced. This is a clear win except on
1138/// targets with multiple condition code registers (PowerPC), where it might
1139/// lose; some adjustment may be wanted there.
1140///
1141/// Return true if any changes are made.
1142static bool SinkCmpExpression(CmpInst *CI, const TargetLowering *TLI) {
1143 BasicBlock *DefBB = CI->getParent();
1144
1145 // Avoid sinking soft-FP comparisons, since this can move them into a loop.
1146 if (TLI && TLI->useSoftFloat() && isa<FCmpInst>(CI))
1147 return false;
1148
1149 // Only insert a cmp in each block once.
1150 DenseMap<BasicBlock*, CmpInst*> InsertedCmps;
1151
1152 bool MadeChange = false;
1153 for (Value::user_iterator UI = CI->user_begin(), E = CI->user_end();
1154 UI != E; ) {
1155 Use &TheUse = UI.getUse();
1156 Instruction *User = cast<Instruction>(*UI);
1157
1158 // Preincrement use iterator so we don't invalidate it.
1159 ++UI;
1160
1161 // Don't bother for PHI nodes.
1162 if (isa<PHINode>(User))
1163 continue;
1164
1165 // Figure out which BB this cmp is used in.
1166 BasicBlock *UserBB = User->getParent();
1167
1168 // If this user is in the same block as the cmp, don't change the cmp.
1169 if (UserBB == DefBB) continue;
1170
1171 // If we have already inserted a cmp into this block, use it.
1172 CmpInst *&InsertedCmp = InsertedCmps[UserBB];
1173
1174 if (!InsertedCmp) {
1175 BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
1176 assert(InsertPt != UserBB->end())(static_cast <bool> (InsertPt != UserBB->end()) ? void
(0) : __assert_fail ("InsertPt != UserBB->end()", "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 1176, __extension__ __PRETTY_FUNCTION__))
;
1177 InsertedCmp =
1178 CmpInst::Create(CI->getOpcode(), CI->getPredicate(),
1179 CI->getOperand(0), CI->getOperand(1), "", &*InsertPt);
1180 // Propagate the debug info.
1181 InsertedCmp->setDebugLoc(CI->getDebugLoc());
1182 }
1183
1184 // Replace a use of the cmp with a use of the new cmp.
1185 TheUse = InsertedCmp;
1186 MadeChange = true;
1187 ++NumCmpUses;
1188 }
1189
1190 // If we removed all uses, nuke the cmp.
1191 if (CI->use_empty()) {
1192 CI->eraseFromParent();
1193 MadeChange = true;
1194 }
1195
1196 return MadeChange;
1197}
1198
1199static bool OptimizeCmpExpression(CmpInst *CI, const TargetLowering *TLI) {
1200 if (SinkCmpExpression(CI, TLI))
1201 return true;
1202
1203 if (CombineUAddWithOverflow(CI))
1204 return true;
1205
1206 return false;
1207}
1208
1209/// Duplicate and sink the given 'and' instruction into user blocks where it is
1210/// used in a compare to allow isel to generate better code for targets where
1211/// this operation can be combined.
1212///
1213/// Return true if any changes are made.
1214static bool sinkAndCmp0Expression(Instruction *AndI,
1215 const TargetLowering &TLI,
1216 SetOfInstrs &InsertedInsts) {
1217 // Double-check that we're not trying to optimize an instruction that was
1218 // already optimized by some other part of this pass.
1219 assert(!InsertedInsts.count(AndI) &&(static_cast <bool> (!InsertedInsts.count(AndI) &&
"Attempting to optimize already optimized and instruction") ?
void (0) : __assert_fail ("!InsertedInsts.count(AndI) && \"Attempting to optimize already optimized and instruction\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 1220, __extension__ __PRETTY_FUNCTION__))
1220 "Attempting to optimize already optimized and instruction")(static_cast <bool> (!InsertedInsts.count(AndI) &&
"Attempting to optimize already optimized and instruction") ?
void (0) : __assert_fail ("!InsertedInsts.count(AndI) && \"Attempting to optimize already optimized and instruction\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 1220, __extension__ __PRETTY_FUNCTION__))
;
1221 (void) InsertedInsts;
1222
1223 // Nothing to do for single use in same basic block.
1224 if (AndI->hasOneUse() &&
1225 AndI->getParent() == cast<Instruction>(*AndI->user_begin())->getParent())
1226 return false;
1227
1228 // Try to avoid cases where sinking/duplicating is likely to increase register
1229 // pressure.
1230 if (!isa<ConstantInt>(AndI->getOperand(0)) &&
1231 !isa<ConstantInt>(AndI->getOperand(1)) &&
1232 AndI->getOperand(0)->hasOneUse() && AndI->getOperand(1)->hasOneUse())
1233 return false;
1234
1235 for (auto *U : AndI->users()) {
1236 Instruction *User = cast<Instruction>(U);
1237
1238 // Only sink for and mask feeding icmp with 0.
1239 if (!isa<ICmpInst>(User))
1240 return false;
1241
1242 auto *CmpC = dyn_cast<ConstantInt>(User->getOperand(1));
1243 if (!CmpC || !CmpC->isZero())
1244 return false;
1245 }
1246
1247 if (!TLI.isMaskAndCmp0FoldingBeneficial(*AndI))
1248 return false;
1249
1250 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)
;
1251 DEBUG(AndI->getParent()->dump())do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { AndI->getParent()->dump(); } } while
(false)
;
1252
1253 // Push the 'and' into the same block as the icmp 0. There should only be
1254 // one (icmp (and, 0)) in each block, since CSE/GVN should have removed any
1255 // others, so we don't need to keep track of which BBs we insert into.
1256 for (Value::user_iterator UI = AndI->user_begin(), E = AndI->user_end();
1257 UI != E; ) {
1258 Use &TheUse = UI.getUse();
1259 Instruction *User = cast<Instruction>(*UI);
1260
1261 // Preincrement use iterator so we don't invalidate it.
1262 ++UI;
1263
1264 DEBUG(dbgs() << "sinking 'and' use: " << *User << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "sinking 'and' use: " <<
*User << "\n"; } } while (false)
;
1265
1266 // Keep the 'and' in the same place if the use is already in the same block.
1267 Instruction *InsertPt =
1268 User->getParent() == AndI->getParent() ? AndI : User;
1269 Instruction *InsertedAnd =
1270 BinaryOperator::Create(Instruction::And, AndI->getOperand(0),
1271 AndI->getOperand(1), "", InsertPt);
1272 // Propagate the debug info.
1273 InsertedAnd->setDebugLoc(AndI->getDebugLoc());
1274
1275 // Replace a use of the 'and' with a use of the new 'and'.
1276 TheUse = InsertedAnd;
1277 ++NumAndUses;
1278 DEBUG(User->getParent()->dump())do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { User->getParent()->dump(); } } while
(false)
;
1279 }
1280
1281 // We removed all uses, nuke the and.
1282 AndI->eraseFromParent();
1283 return true;
1284}
1285
1286/// Check if the candidates could be combined with a shift instruction, which
1287/// includes:
1288/// 1. Truncate instruction
1289/// 2. And instruction and the imm is a mask of the low bits:
1290/// imm & (imm+1) == 0
1291static bool isExtractBitsCandidateUse(Instruction *User) {
1292 if (!isa<TruncInst>(User)) {
1293 if (User->getOpcode() != Instruction::And ||
1294 !isa<ConstantInt>(User->getOperand(1)))
1295 return false;
1296
1297 const APInt &Cimm = cast<ConstantInt>(User->getOperand(1))->getValue();
1298
1299 if ((Cimm & (Cimm + 1)).getBoolValue())
1300 return false;
1301 }
1302 return true;
1303}
1304
1305/// Sink both shift and truncate instruction to the use of truncate's BB.
1306static bool
1307SinkShiftAndTruncate(BinaryOperator *ShiftI, Instruction *User, ConstantInt *CI,
1308 DenseMap<BasicBlock *, BinaryOperator *> &InsertedShifts,
1309 const TargetLowering &TLI, const DataLayout &DL) {
1310 BasicBlock *UserBB = User->getParent();
1311 DenseMap<BasicBlock *, CastInst *> InsertedTruncs;
1312 TruncInst *TruncI = dyn_cast<TruncInst>(User);
1313 bool MadeChange = false;
1314
1315 for (Value::user_iterator TruncUI = TruncI->user_begin(),
1316 TruncE = TruncI->user_end();
1317 TruncUI != TruncE;) {
1318
1319 Use &TruncTheUse = TruncUI.getUse();
1320 Instruction *TruncUser = cast<Instruction>(*TruncUI);
1321 // Preincrement use iterator so we don't invalidate it.
1322
1323 ++TruncUI;
1324
1325 int ISDOpcode = TLI.InstructionOpcodeToISD(TruncUser->getOpcode());
1326 if (!ISDOpcode)
1327 continue;
1328
1329 // If the use is actually a legal node, there will not be an
1330 // implicit truncate.
1331 // FIXME: always querying the result type is just an
1332 // approximation; some nodes' legality is determined by the
1333 // operand or other means. There's no good way to find out though.
1334 if (TLI.isOperationLegalOrCustom(
1335 ISDOpcode, TLI.getValueType(DL, TruncUser->getType(), true)))
1336 continue;
1337
1338 // Don't bother for PHI nodes.
1339 if (isa<PHINode>(TruncUser))
1340 continue;
1341
1342 BasicBlock *TruncUserBB = TruncUser->getParent();
1343
1344 if (UserBB == TruncUserBB)
1345 continue;
1346
1347 BinaryOperator *&InsertedShift = InsertedShifts[TruncUserBB];
1348 CastInst *&InsertedTrunc = InsertedTruncs[TruncUserBB];
1349
1350 if (!InsertedShift && !InsertedTrunc) {
1351 BasicBlock::iterator InsertPt = TruncUserBB->getFirstInsertionPt();
1352 assert(InsertPt != TruncUserBB->end())(static_cast <bool> (InsertPt != TruncUserBB->end())
? void (0) : __assert_fail ("InsertPt != TruncUserBB->end()"
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 1352, __extension__ __PRETTY_FUNCTION__))
;
1353 // Sink the shift
1354 if (ShiftI->getOpcode() == Instruction::AShr)
1355 InsertedShift = BinaryOperator::CreateAShr(ShiftI->getOperand(0), CI,
1356 "", &*InsertPt);
1357 else
1358 InsertedShift = BinaryOperator::CreateLShr(ShiftI->getOperand(0), CI,
1359 "", &*InsertPt);
1360
1361 // Sink the trunc
1362 BasicBlock::iterator TruncInsertPt = TruncUserBB->getFirstInsertionPt();
1363 TruncInsertPt++;
1364 assert(TruncInsertPt != TruncUserBB->end())(static_cast <bool> (TruncInsertPt != TruncUserBB->end
()) ? void (0) : __assert_fail ("TruncInsertPt != TruncUserBB->end()"
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 1364, __extension__ __PRETTY_FUNCTION__))
;
1365
1366 InsertedTrunc = CastInst::Create(TruncI->getOpcode(), InsertedShift,
1367 TruncI->getType(), "", &*TruncInsertPt);
1368
1369 MadeChange = true;
1370
1371 TruncTheUse = InsertedTrunc;
1372 }
1373 }
1374 return MadeChange;
1375}
1376
1377/// Sink the shift *right* instruction into user blocks if the uses could
1378/// potentially be combined with this shift instruction and generate BitExtract
1379/// instruction. It will only be applied if the architecture supports BitExtract
1380/// instruction. Here is an example:
1381/// BB1:
1382/// %x.extract.shift = lshr i64 %arg1, 32
1383/// BB2:
1384/// %x.extract.trunc = trunc i64 %x.extract.shift to i16
1385/// ==>
1386///
1387/// BB2:
1388/// %x.extract.shift.1 = lshr i64 %arg1, 32
1389/// %x.extract.trunc = trunc i64 %x.extract.shift.1 to i16
1390///
1391/// CodeGen will recoginze the pattern in BB2 and generate BitExtract
1392/// instruction.
1393/// Return true if any changes are made.
1394static bool OptimizeExtractBits(BinaryOperator *ShiftI, ConstantInt *CI,
1395 const TargetLowering &TLI,
1396 const DataLayout &DL) {
1397 BasicBlock *DefBB = ShiftI->getParent();
1398
1399 /// Only insert instructions in each block once.
1400 DenseMap<BasicBlock *, BinaryOperator *> InsertedShifts;
1401
1402 bool shiftIsLegal = TLI.isTypeLegal(TLI.getValueType(DL, ShiftI->getType()));
1403
1404 bool MadeChange = false;
1405 for (Value::user_iterator UI = ShiftI->user_begin(), E = ShiftI->user_end();
1406 UI != E;) {
1407 Use &TheUse = UI.getUse();
1408 Instruction *User = cast<Instruction>(*UI);
1409 // Preincrement use iterator so we don't invalidate it.
1410 ++UI;
1411
1412 // Don't bother for PHI nodes.
1413 if (isa<PHINode>(User))
1414 continue;
1415
1416 if (!isExtractBitsCandidateUse(User))
1417 continue;
1418
1419 BasicBlock *UserBB = User->getParent();
1420
1421 if (UserBB == DefBB) {
1422 // If the shift and truncate instruction are in the same BB. The use of
1423 // the truncate(TruncUse) may still introduce another truncate if not
1424 // legal. In this case, we would like to sink both shift and truncate
1425 // instruction to the BB of TruncUse.
1426 // for example:
1427 // BB1:
1428 // i64 shift.result = lshr i64 opnd, imm
1429 // trunc.result = trunc shift.result to i16
1430 //
1431 // BB2:
1432 // ----> We will have an implicit truncate here if the architecture does
1433 // not have i16 compare.
1434 // cmp i16 trunc.result, opnd2
1435 //
1436 if (isa<TruncInst>(User) && shiftIsLegal
1437 // If the type of the truncate is legal, no trucate will be
1438 // introduced in other basic blocks.
1439 &&
1440 (!TLI.isTypeLegal(TLI.getValueType(DL, User->getType()))))
1441 MadeChange =
1442 SinkShiftAndTruncate(ShiftI, User, CI, InsertedShifts, TLI, DL);
1443
1444 continue;
1445 }
1446 // If we have already inserted a shift into this block, use it.
1447 BinaryOperator *&InsertedShift = InsertedShifts[UserBB];
1448
1449 if (!InsertedShift) {
1450 BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
1451 assert(InsertPt != UserBB->end())(static_cast <bool> (InsertPt != UserBB->end()) ? void
(0) : __assert_fail ("InsertPt != UserBB->end()", "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 1451, __extension__ __PRETTY_FUNCTION__))
;
1452
1453 if (ShiftI->getOpcode() == Instruction::AShr)
1454 InsertedShift = BinaryOperator::CreateAShr(ShiftI->getOperand(0), CI,
1455 "", &*InsertPt);
1456 else
1457 InsertedShift = BinaryOperator::CreateLShr(ShiftI->getOperand(0), CI,
1458 "", &*InsertPt);
1459
1460 MadeChange = true;
1461 }
1462
1463 // Replace a use of the shift with a use of the new shift.
1464 TheUse = InsertedShift;
1465 }
1466
1467 // If we removed all uses, nuke the shift.
1468 if (ShiftI->use_empty())
1469 ShiftI->eraseFromParent();
1470
1471 return MadeChange;
1472}
1473
1474/// If counting leading or trailing zeros is an expensive operation and a zero
1475/// input is defined, add a check for zero to avoid calling the intrinsic.
1476///
1477/// We want to transform:
1478/// %z = call i64 @llvm.cttz.i64(i64 %A, i1 false)
1479///
1480/// into:
1481/// entry:
1482/// %cmpz = icmp eq i64 %A, 0
1483/// br i1 %cmpz, label %cond.end, label %cond.false
1484/// cond.false:
1485/// %z = call i64 @llvm.cttz.i64(i64 %A, i1 true)
1486/// br label %cond.end
1487/// cond.end:
1488/// %ctz = phi i64 [ 64, %entry ], [ %z, %cond.false ]
1489///
1490/// If the transform is performed, return true and set ModifiedDT to true.
1491static bool despeculateCountZeros(IntrinsicInst *CountZeros,
1492 const TargetLowering *TLI,
1493 const DataLayout *DL,
1494 bool &ModifiedDT) {
1495 if (!TLI || !DL)
1496 return false;
1497
1498 // If a zero input is undefined, it doesn't make sense to despeculate that.
1499 if (match(CountZeros->getOperand(1), m_One()))
1500 return false;
1501
1502 // If it's cheap to speculate, there's nothing to do.
1503 auto IntrinsicID = CountZeros->getIntrinsicID();
1504 if ((IntrinsicID == Intrinsic::cttz && TLI->isCheapToSpeculateCttz()) ||
1505 (IntrinsicID == Intrinsic::ctlz && TLI->isCheapToSpeculateCtlz()))
1506 return false;
1507
1508 // Only handle legal scalar cases. Anything else requires too much work.
1509 Type *Ty = CountZeros->getType();
1510 unsigned SizeInBits = Ty->getPrimitiveSizeInBits();
1511 if (Ty->isVectorTy() || SizeInBits > DL->getLargestLegalIntTypeSizeInBits())
1512 return false;
1513
1514 // The intrinsic will be sunk behind a compare against zero and branch.
1515 BasicBlock *StartBlock = CountZeros->getParent();
1516 BasicBlock *CallBlock = StartBlock->splitBasicBlock(CountZeros, "cond.false");
1517
1518 // Create another block after the count zero intrinsic. A PHI will be added
1519 // in this block to select the result of the intrinsic or the bit-width
1520 // constant if the input to the intrinsic is zero.
1521 BasicBlock::iterator SplitPt = ++(BasicBlock::iterator(CountZeros));
1522 BasicBlock *EndBlock = CallBlock->splitBasicBlock(SplitPt, "cond.end");
1523
1524 // Set up a builder to create a compare, conditional branch, and PHI.
1525 IRBuilder<> Builder(CountZeros->getContext());
1526 Builder.SetInsertPoint(StartBlock->getTerminator());
1527 Builder.SetCurrentDebugLocation(CountZeros->getDebugLoc());
1528
1529 // Replace the unconditional branch that was created by the first split with
1530 // a compare against zero and a conditional branch.
1531 Value *Zero = Constant::getNullValue(Ty);
1532 Value *Cmp = Builder.CreateICmpEQ(CountZeros->getOperand(0), Zero, "cmpz");
1533 Builder.CreateCondBr(Cmp, EndBlock, CallBlock);
1534 StartBlock->getTerminator()->eraseFromParent();
1535
1536 // Create a PHI in the end block to select either the output of the intrinsic
1537 // or the bit width of the operand.
1538 Builder.SetInsertPoint(&EndBlock->front());
1539 PHINode *PN = Builder.CreatePHI(Ty, 2, "ctz");
1540 CountZeros->replaceAllUsesWith(PN);
1541 Value *BitWidth = Builder.getInt(APInt(SizeInBits, SizeInBits));
1542 PN->addIncoming(BitWidth, StartBlock);
1543 PN->addIncoming(CountZeros, CallBlock);
1544
1545 // We are explicitly handling the zero case, so we can set the intrinsic's
1546 // undefined zero argument to 'true'. This will also prevent reprocessing the
1547 // intrinsic; we only despeculate when a zero input is defined.
1548 CountZeros->setArgOperand(1, Builder.getTrue());
1549 ModifiedDT = true;
1550 return true;
1551}
1552
1553bool CodeGenPrepare::optimizeCallInst(CallInst *CI, bool &ModifiedDT) {
1554 BasicBlock *BB = CI->getParent();
1555
1556 // Lower inline assembly if we can.
1557 // If we found an inline asm expession, and if the target knows how to
1558 // lower it to normal LLVM code, do so now.
1559 if (TLI && isa<InlineAsm>(CI->getCalledValue())) {
1560 if (TLI->ExpandInlineAsm(CI)) {
1561 // Avoid invalidating the iterator.
1562 CurInstIterator = BB->begin();
1563 // Avoid processing instructions out of order, which could cause
1564 // reuse before a value is defined.
1565 SunkAddrs.clear();
1566 return true;
1567 }
1568 // Sink address computing for memory operands into the block.
1569 if (optimizeInlineAsmInst(CI))
1570 return true;
1571 }
1572
1573 // Align the pointer arguments to this call if the target thinks it's a good
1574 // idea
1575 unsigned MinSize, PrefAlign;
1576 if (TLI && TLI->shouldAlignPointerArgs(CI, MinSize, PrefAlign)) {
1577 for (auto &Arg : CI->arg_operands()) {
1578 // We want to align both objects whose address is used directly and
1579 // objects whose address is used in casts and GEPs, though it only makes
1580 // sense for GEPs if the offset is a multiple of the desired alignment and
1581 // if size - offset meets the size threshold.
1582 if (!Arg->getType()->isPointerTy())
1583 continue;
1584 APInt Offset(DL->getIndexSizeInBits(
1585 cast<PointerType>(Arg->getType())->getAddressSpace()),
1586 0);
1587 Value *Val = Arg->stripAndAccumulateInBoundsConstantOffsets(*DL, Offset);
1588 uint64_t Offset2 = Offset.getLimitedValue();
1589 if ((Offset2 & (PrefAlign-1)) != 0)
1590 continue;
1591 AllocaInst *AI;
1592 if ((AI = dyn_cast<AllocaInst>(Val)) && AI->getAlignment() < PrefAlign &&
1593 DL->getTypeAllocSize(AI->getAllocatedType()) >= MinSize + Offset2)
1594 AI->setAlignment(PrefAlign);
1595 // Global variables can only be aligned if they are defined in this
1596 // object (i.e. they are uniquely initialized in this object), and
1597 // over-aligning global variables that have an explicit section is
1598 // forbidden.
1599 GlobalVariable *GV;
1600 if ((GV = dyn_cast<GlobalVariable>(Val)) && GV->canIncreaseAlignment() &&
1601 GV->getPointerAlignment(*DL) < PrefAlign &&
1602 DL->getTypeAllocSize(GV->getValueType()) >=
1603 MinSize + Offset2)
1604 GV->setAlignment(PrefAlign);
1605 }
1606 // If this is a memcpy (or similar) then we may be able to improve the
1607 // alignment
1608 if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(CI)) {
1609 unsigned DestAlign = getKnownAlignment(MI->getDest(), *DL);
1610 if (DestAlign > MI->getDestAlignment())
1611 MI->setDestAlignment(DestAlign);
1612 if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(MI)) {
1613 unsigned SrcAlign = getKnownAlignment(MTI->getSource(), *DL);
1614 if (SrcAlign > MTI->getSourceAlignment())
1615 MTI->setSourceAlignment(SrcAlign);
1616 }
1617 }
1618 }
1619
1620 // If we have a cold call site, try to sink addressing computation into the
1621 // cold block. This interacts with our handling for loads and stores to
1622 // ensure that we can fold all uses of a potential addressing computation
1623 // into their uses. TODO: generalize this to work over profiling data
1624 if (!OptSize && CI->hasFnAttr(Attribute::Cold))
1625 for (auto &Arg : CI->arg_operands()) {
1626 if (!Arg->getType()->isPointerTy())
1627 continue;
1628 unsigned AS = Arg->getType()->getPointerAddressSpace();
1629 return optimizeMemoryInst(CI, Arg, Arg->getType(), AS);
1630 }
1631
1632 IntrinsicInst *II = dyn_cast<IntrinsicInst>(CI);
1633 if (II) {
1634 switch (II->getIntrinsicID()) {
1635 default: break;
1636 case Intrinsic::objectsize: {
1637 // Lower all uses of llvm.objectsize.*
1638 ConstantInt *RetVal =
1639 lowerObjectSizeCall(II, *DL, TLInfo, /*MustSucceed=*/true);
1640 // Substituting this can cause recursive simplifications, which can
1641 // invalidate our iterator. Use a WeakTrackingVH to hold onto it in case
1642 // this
1643 // happens.
1644 Value *CurValue = &*CurInstIterator;
1645 WeakTrackingVH IterHandle(CurValue);
1646
1647 replaceAndRecursivelySimplify(CI, RetVal, TLInfo, nullptr);
1648
1649 // If the iterator instruction was recursively deleted, start over at the
1650 // start of the block.
1651 if (IterHandle != CurValue) {
1652 CurInstIterator = BB->begin();
1653 SunkAddrs.clear();
1654 }
1655 return true;
1656 }
1657 case Intrinsic::aarch64_stlxr:
1658 case Intrinsic::aarch64_stxr: {
1659 ZExtInst *ExtVal = dyn_cast<ZExtInst>(CI->getArgOperand(0));
1660 if (!ExtVal || !ExtVal->hasOneUse() ||
1661 ExtVal->getParent() == CI->getParent())
1662 return false;
1663 // Sink a zext feeding stlxr/stxr before it, so it can be folded into it.
1664 ExtVal->moveBefore(CI);
1665 // Mark this instruction as "inserted by CGP", so that other
1666 // optimizations don't touch it.
1667 InsertedInsts.insert(ExtVal);
1668 return true;
1669 }
1670 case Intrinsic::invariant_group_barrier:
1671 II->replaceAllUsesWith(II->getArgOperand(0));
1672 II->eraseFromParent();
1673 return true;
1674
1675 case Intrinsic::cttz:
1676 case Intrinsic::ctlz:
1677 // If counting zeros is expensive, try to avoid it.
1678 return despeculateCountZeros(II, TLI, DL, ModifiedDT);
1679 }
1680
1681 if (TLI) {
1682 SmallVector<Value*, 2> PtrOps;
1683 Type *AccessTy;
1684 if (TLI->getAddrModeArguments(II, PtrOps, AccessTy))
1685 while (!PtrOps.empty()) {
1686 Value *PtrVal = PtrOps.pop_back_val();
1687 unsigned AS = PtrVal->getType()->getPointerAddressSpace();
1688 if (optimizeMemoryInst(II, PtrVal, AccessTy, AS))
1689 return true;
1690 }
1691 }
1692 }
1693
1694 // From here on out we're working with named functions.
1695 if (!CI->getCalledFunction()) return false;
1696
1697 // Lower all default uses of _chk calls. This is very similar
1698 // to what InstCombineCalls does, but here we are only lowering calls
1699 // to fortified library functions (e.g. __memcpy_chk) that have the default
1700 // "don't know" as the objectsize. Anything else should be left alone.
1701 FortifiedLibCallSimplifier Simplifier(TLInfo, true);
1702 if (Value *V = Simplifier.optimizeCall(CI)) {
1703 CI->replaceAllUsesWith(V);
1704 CI->eraseFromParent();
1705 return true;
1706 }
1707
1708 return false;
1709}
1710
1711/// Look for opportunities to duplicate return instructions to the predecessor
1712/// to enable tail call optimizations. The case it is currently looking for is:
1713/// @code
1714/// bb0:
1715/// %tmp0 = tail call i32 @f0()
1716/// br label %return
1717/// bb1:
1718/// %tmp1 = tail call i32 @f1()
1719/// br label %return
1720/// bb2:
1721/// %tmp2 = tail call i32 @f2()
1722/// br label %return
1723/// return:
1724/// %retval = phi i32 [ %tmp0, %bb0 ], [ %tmp1, %bb1 ], [ %tmp2, %bb2 ]
1725/// ret i32 %retval
1726/// @endcode
1727///
1728/// =>
1729///
1730/// @code
1731/// bb0:
1732/// %tmp0 = tail call i32 @f0()
1733/// ret i32 %tmp0
1734/// bb1:
1735/// %tmp1 = tail call i32 @f1()
1736/// ret i32 %tmp1
1737/// bb2:
1738/// %tmp2 = tail call i32 @f2()
1739/// ret i32 %tmp2
1740/// @endcode
1741bool CodeGenPrepare::dupRetToEnableTailCallOpts(BasicBlock *BB) {
1742 if (!TLI)
1743 return false;
1744
1745 ReturnInst *RetI = dyn_cast<ReturnInst>(BB->getTerminator());
1746 if (!RetI)
1747 return false;
1748
1749 PHINode *PN = nullptr;
1750 BitCastInst *BCI = nullptr;
1751 Value *V = RetI->getReturnValue();
1752 if (V) {
1753 BCI = dyn_cast<BitCastInst>(V);
1754 if (BCI)
1755 V = BCI->getOperand(0);
1756
1757 PN = dyn_cast<PHINode>(V);
1758 if (!PN)
1759 return false;
1760 }
1761
1762 if (PN && PN->getParent() != BB)
1763 return false;
1764
1765 // Make sure there are no instructions between the PHI and return, or that the
1766 // return is the first instruction in the block.
1767 if (PN) {
1768 BasicBlock::iterator BI = BB->begin();
1769 do { ++BI; } while (isa<DbgInfoIntrinsic>(BI));
1770 if (&*BI == BCI)
1771 // Also skip over the bitcast.
1772 ++BI;
1773 if (&*BI != RetI)
1774 return false;
1775 } else {
1776 BasicBlock::iterator BI = BB->begin();
1777 while (isa<DbgInfoIntrinsic>(BI)) ++BI;
1778 if (&*BI != RetI)
1779 return false;
1780 }
1781
1782 /// Only dup the ReturnInst if the CallInst is likely to be emitted as a tail
1783 /// call.
1784 const Function *F = BB->getParent();
1785 SmallVector<CallInst*, 4> TailCalls;
1786 if (PN) {
1787 for (unsigned I = 0, E = PN->getNumIncomingValues(); I != E; ++I) {
1788 CallInst *CI = dyn_cast<CallInst>(PN->getIncomingValue(I));
1789 // Make sure the phi value is indeed produced by the tail call.
1790 if (CI && CI->hasOneUse() && CI->getParent() == PN->getIncomingBlock(I) &&
1791 TLI->mayBeEmittedAsTailCall(CI) &&
1792 attributesPermitTailCall(F, CI, RetI, *TLI))
1793 TailCalls.push_back(CI);
1794 }
1795 } else {
1796 SmallPtrSet<BasicBlock*, 4> VisitedBBs;
1797 for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB); PI != PE; ++PI) {
1798 if (!VisitedBBs.insert(*PI).second)
1799 continue;
1800
1801 BasicBlock::InstListType &InstList = (*PI)->getInstList();
1802 BasicBlock::InstListType::reverse_iterator RI = InstList.rbegin();
1803 BasicBlock::InstListType::reverse_iterator RE = InstList.rend();
1804 do { ++RI; } while (RI != RE && isa<DbgInfoIntrinsic>(&*RI));
1805 if (RI == RE)
1806 continue;
1807
1808 CallInst *CI = dyn_cast<CallInst>(&*RI);
1809 if (CI && CI->use_empty() && TLI->mayBeEmittedAsTailCall(CI) &&
1810 attributesPermitTailCall(F, CI, RetI, *TLI))
1811 TailCalls.push_back(CI);
1812 }
1813 }
1814
1815 bool Changed = false;
1816 for (unsigned i = 0, e = TailCalls.size(); i != e; ++i) {
1817 CallInst *CI = TailCalls[i];
1818 CallSite CS(CI);
1819
1820 // Conservatively require the attributes of the call to match those of the
1821 // return. Ignore noalias because it doesn't affect the call sequence.
1822 AttributeList CalleeAttrs = CS.getAttributes();
1823 if (AttrBuilder(CalleeAttrs, AttributeList::ReturnIndex)
1824 .removeAttribute(Attribute::NoAlias) !=
1825 AttrBuilder(CalleeAttrs, AttributeList::ReturnIndex)
1826 .removeAttribute(Attribute::NoAlias))
1827 continue;
1828
1829 // Make sure the call instruction is followed by an unconditional branch to
1830 // the return block.
1831 BasicBlock *CallBB = CI->getParent();
1832 BranchInst *BI = dyn_cast<BranchInst>(CallBB->getTerminator());
1833 if (!BI || !BI->isUnconditional() || BI->getSuccessor(0) != BB)
1834 continue;
1835
1836 // Duplicate the return into CallBB.
1837 (void)FoldReturnIntoUncondBranch(RetI, BB, CallBB);
1838 ModifiedDT = Changed = true;
1839 ++NumRetsDup;
1840 }
1841
1842 // If we eliminated all predecessors of the block, delete the block now.
1843 if (Changed && !BB->hasAddressTaken() && pred_begin(BB) == pred_end(BB))
1844 BB->eraseFromParent();
1845
1846 return Changed;
1847}
1848
1849//===----------------------------------------------------------------------===//
1850// Memory Optimization
1851//===----------------------------------------------------------------------===//
1852
1853namespace {
1854
1855/// This is an extended version of TargetLowering::AddrMode
1856/// which holds actual Value*'s for register values.
1857struct ExtAddrMode : public TargetLowering::AddrMode {
1858 Value *BaseReg = nullptr;
1859 Value *ScaledReg = nullptr;
1860 Value *OriginalValue = nullptr;
1861
1862 enum FieldName {
1863 NoField = 0x00,
1864 BaseRegField = 0x01,
1865 BaseGVField = 0x02,
1866 BaseOffsField = 0x04,
1867 ScaledRegField = 0x08,
1868 ScaleField = 0x10,
1869 MultipleFields = 0xff
1870 };
1871
1872 ExtAddrMode() = default;
1873
1874 void print(raw_ostream &OS) const;
1875 void dump() const;
1876
1877 FieldName compare(const ExtAddrMode &other) {
1878 // First check that the types are the same on each field, as differing types
1879 // is something we can't cope with later on.
1880 if (BaseReg && other.BaseReg &&
1881 BaseReg->getType() != other.BaseReg->getType())
1882 return MultipleFields;
1883 if (BaseGV && other.BaseGV &&
1884 BaseGV->getType() != other.BaseGV->getType())
1885 return MultipleFields;
1886 if (ScaledReg && other.ScaledReg &&
1887 ScaledReg->getType() != other.ScaledReg->getType())
1888 return MultipleFields;
1889
1890 // Check each field to see if it differs.
1891 unsigned Result = NoField;
1892 if (BaseReg != other.BaseReg)
1893 Result |= BaseRegField;
1894 if (BaseGV != other.BaseGV)
1895 Result |= BaseGVField;
1896 if (BaseOffs != other.BaseOffs)
1897 Result |= BaseOffsField;
1898 if (ScaledReg != other.ScaledReg)
1899 Result |= ScaledRegField;
1900 // Don't count 0 as being a different scale, because that actually means
1901 // unscaled (which will already be counted by having no ScaledReg).
1902 if (Scale && other.Scale && Scale != other.Scale)
1903 Result |= ScaleField;
1904
1905 if (countPopulation(Result) > 1)
1906 return MultipleFields;
1907 else
1908 return static_cast<FieldName>(Result);
1909 }
1910
1911 // An AddrMode is trivial if it involves no calculation i.e. it is just a base
1912 // with no offset.
1913 bool isTrivial() {
1914 // An AddrMode is (BaseGV + BaseReg + BaseOffs + ScaleReg * Scale) so it is
1915 // trivial if at most one of these terms is nonzero, except that BaseGV and
1916 // BaseReg both being zero actually means a null pointer value, which we
1917 // consider to be 'non-zero' here.
1918 return !BaseOffs && !Scale && !(BaseGV && BaseReg);
1919 }
1920
1921 Value *GetFieldAsValue(FieldName Field, Type *IntPtrTy) {
1922 switch (Field) {
1923 default:
1924 return nullptr;
1925 case BaseRegField:
1926 return BaseReg;
1927 case BaseGVField:
1928 return BaseGV;
1929 case ScaledRegField:
1930 return ScaledReg;
1931 case BaseOffsField:
1932 return ConstantInt::get(IntPtrTy, BaseOffs);
1933 }
1934 }
1935
1936 void SetCombinedField(FieldName Field, Value *V,
1937 const SmallVectorImpl<ExtAddrMode> &AddrModes) {
1938 switch (Field) {
1939 default:
1940 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-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 1940)
;
1941 break;
1942 case ExtAddrMode::BaseRegField:
1943 BaseReg = V;
1944 break;
1945 case ExtAddrMode::BaseGVField:
1946 // A combined BaseGV is an Instruction, not a GlobalValue, so it goes
1947 // in the BaseReg field.
1948 assert(BaseReg == nullptr)(static_cast <bool> (BaseReg == nullptr) ? void (0) : __assert_fail
("BaseReg == nullptr", "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 1948, __extension__ __PRETTY_FUNCTION__))
;
1949 BaseReg = V;
1950 BaseGV = nullptr;
1951 break;
1952 case ExtAddrMode::ScaledRegField:
1953 ScaledReg = V;
1954 // If we have a mix of scaled and unscaled addrmodes then we want scale
1955 // to be the scale and not zero.
1956 if (!Scale)
1957 for (const ExtAddrMode &AM : AddrModes)
1958 if (AM.Scale) {
1959 Scale = AM.Scale;
1960 break;
1961 }
1962 break;
1963 case ExtAddrMode::BaseOffsField:
1964 // The offset is no longer a constant, so it goes in ScaledReg with a
1965 // scale of 1.
1966 assert(ScaledReg == nullptr)(static_cast <bool> (ScaledReg == nullptr) ? void (0) :
__assert_fail ("ScaledReg == nullptr", "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 1966, __extension__ __PRETTY_FUNCTION__))
;
1967 ScaledReg = V;
1968 Scale = 1;
1969 BaseOffs = 0;
1970 break;
1971 }
1972 }
1973};
1974
1975} // end anonymous namespace
1976
1977#ifndef NDEBUG
1978static inline raw_ostream &operator<<(raw_ostream &OS, const ExtAddrMode &AM) {
1979 AM.print(OS);
1980 return OS;
1981}
1982#endif
1983
1984#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
1985void ExtAddrMode::print(raw_ostream &OS) const {
1986 bool NeedPlus = false;
1987 OS << "[";
1988 if (BaseGV) {
1989 OS << (NeedPlus ? " + " : "")
1990 << "GV:";
1991 BaseGV->printAsOperand(OS, /*PrintType=*/false);
1992 NeedPlus = true;
1993 }
1994
1995 if (BaseOffs) {
1996 OS << (NeedPlus ? " + " : "")
1997 << BaseOffs;
1998 NeedPlus = true;
1999 }
2000
2001 if (BaseReg) {
2002 OS << (NeedPlus ? " + " : "")
2003 << "Base:";
2004 BaseReg->printAsOperand(OS, /*PrintType=*/false);
2005 NeedPlus = true;
2006 }
2007 if (Scale) {
2008 OS << (NeedPlus ? " + " : "")
2009 << Scale << "*";
2010 ScaledReg->printAsOperand(OS, /*PrintType=*/false);
2011 }
2012
2013 OS << ']';
2014}
2015
2016LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void ExtAddrMode::dump() const {
2017 print(dbgs());
2018 dbgs() << '\n';
2019}
2020#endif
2021
2022namespace {
2023
2024/// \brief This class provides transaction based operation on the IR.
2025/// Every change made through this class is recorded in the internal state and
2026/// can be undone (rollback) until commit is called.
2027class TypePromotionTransaction {
2028 /// \brief This represents the common interface of the individual transaction.
2029 /// Each class implements the logic for doing one specific modification on
2030 /// the IR via the TypePromotionTransaction.
2031 class TypePromotionAction {
2032 protected:
2033 /// The Instruction modified.
2034 Instruction *Inst;
2035
2036 public:
2037 /// \brief Constructor of the action.
2038 /// The constructor performs the related action on the IR.
2039 TypePromotionAction(Instruction *Inst) : Inst(Inst) {}
2040
2041 virtual ~TypePromotionAction() = default;
2042
2043 /// \brief Undo the modification done by this action.
2044 /// When this method is called, the IR must be in the same state as it was
2045 /// before this action was applied.
2046 /// \pre Undoing the action works if and only if the IR is in the exact same
2047 /// state as it was directly after this action was applied.
2048 virtual void undo() = 0;
2049
2050 /// \brief Advocate every change made by this action.
2051 /// When the results on the IR of the action are to be kept, it is important
2052 /// to call this function, otherwise hidden information may be kept forever.
2053 virtual void commit() {
2054 // Nothing to be done, this action is not doing anything.
2055 }
2056 };
2057
2058 /// \brief Utility to remember the position of an instruction.
2059 class InsertionHandler {
2060 /// Position of an instruction.
2061 /// Either an instruction:
2062 /// - Is the first in a basic block: BB is used.
2063 /// - Has a previous instructon: PrevInst is used.
2064 union {
2065 Instruction *PrevInst;
2066 BasicBlock *BB;
2067 } Point;
2068
2069 /// Remember whether or not the instruction had a previous instruction.
2070 bool HasPrevInstruction;
2071
2072 public:
2073 /// \brief Record the position of \p Inst.
2074 InsertionHandler(Instruction *Inst) {
2075 BasicBlock::iterator It = Inst->getIterator();
2076 HasPrevInstruction = (It != (Inst->getParent()->begin()));
2077 if (HasPrevInstruction)
2078 Point.PrevInst = &*--It;
2079 else
2080 Point.BB = Inst->getParent();
2081 }
2082
2083 /// \brief Insert \p Inst at the recorded position.
2084 void insert(Instruction *Inst) {
2085 if (HasPrevInstruction) {
2086 if (Inst->getParent())
2087 Inst->removeFromParent();
2088 Inst->insertAfter(Point.PrevInst);
2089 } else {
2090 Instruction *Position = &*Point.BB->getFirstInsertionPt();
2091 if (Inst->getParent())
2092 Inst->moveBefore(Position);
2093 else
2094 Inst->insertBefore(Position);
2095 }
2096 }
2097 };
2098
2099 /// \brief Move an instruction before another.
2100 class InstructionMoveBefore : public TypePromotionAction {
2101 /// Original position of the instruction.
2102 InsertionHandler Position;
2103
2104 public:
2105 /// \brief Move \p Inst before \p Before.
2106 InstructionMoveBefore(Instruction *Inst, Instruction *Before)
2107 : TypePromotionAction(Inst), Position(Inst) {
2108 DEBUG(dbgs() << "Do: move: " << *Inst << "\nbefore: " << *Before << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: move: " << *
Inst << "\nbefore: " << *Before << "\n"; } }
while (false)
;
2109 Inst->moveBefore(Before);
2110 }
2111
2112 /// \brief Move the instruction back to its original position.
2113 void undo() override {
2114 DEBUG(dbgs() << "Undo: moveBefore: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: moveBefore: " <<
*Inst << "\n"; } } while (false)
;
2115 Position.insert(Inst);
2116 }
2117 };
2118
2119 /// \brief Set the operand of an instruction with a new value.
2120 class OperandSetter : public TypePromotionAction {
2121 /// Original operand of the instruction.
2122 Value *Origin;
2123
2124 /// Index of the modified instruction.
2125 unsigned Idx;
2126
2127 public:
2128 /// \brief Set \p Idx operand of \p Inst with \p NewVal.
2129 OperandSetter(Instruction *Inst, unsigned Idx, Value *NewVal)
2130 : TypePromotionAction(Inst), Idx(Idx) {
2131 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)
2132 << "for:" << *Inst << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: setOperand: " <<
Idx << "\n" << "for:" << *Inst << "\n"
<< "with:" << *NewVal << "\n"; } } while (
false)
2133 << "with:" << *NewVal << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: setOperand: " <<
Idx << "\n" << "for:" << *Inst << "\n"
<< "with:" << *NewVal << "\n"; } } while (
false)
;
2134 Origin = Inst->getOperand(Idx);
2135 Inst->setOperand(Idx, NewVal);
2136 }
2137
2138 /// \brief Restore the original value of the instruction.
2139 void undo() override {
2140 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)
2141 << "for: " << *Inst << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: setOperand:" <<
Idx << "\n" << "for: " << *Inst << "\n"
<< "with: " << *Origin << "\n"; } } while (
false)
2142 << "with: " << *Origin << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: setOperand:" <<
Idx << "\n" << "for: " << *Inst << "\n"
<< "with: " << *Origin << "\n"; } } while (
false)
;
2143 Inst->setOperand(Idx, Origin);
2144 }
2145 };
2146
2147 /// \brief Hide the operands of an instruction.
2148 /// Do as if this instruction was not using any of its operands.
2149 class OperandsHider : public TypePromotionAction {
2150 /// The list of original operands.
2151 SmallVector<Value *, 4> OriginalValues;
2152
2153 public:
2154 /// \brief Remove \p Inst from the uses of the operands of \p Inst.
2155 OperandsHider(Instruction *Inst) : TypePromotionAction(Inst) {
2156 DEBUG(dbgs() << "Do: OperandsHider: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: OperandsHider: " <<
*Inst << "\n"; } } while (false)
;
2157 unsigned NumOpnds = Inst->getNumOperands();
2158 OriginalValues.reserve(NumOpnds);
2159 for (unsigned It = 0; It < NumOpnds; ++It) {
2160 // Save the current operand.
2161 Value *Val = Inst->getOperand(It);
2162 OriginalValues.push_back(Val);
2163 // Set a dummy one.
2164 // We could use OperandSetter here, but that would imply an overhead
2165 // that we are not willing to pay.
2166 Inst->setOperand(It, UndefValue::get(Val->getType()));
2167 }
2168 }
2169
2170 /// \brief Restore the original list of uses.
2171 void undo() override {
2172 DEBUG(dbgs() << "Undo: OperandsHider: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: OperandsHider: "
<< *Inst << "\n"; } } while (false)
;
2173 for (unsigned It = 0, EndIt = OriginalValues.size(); It != EndIt; ++It)
2174 Inst->setOperand(It, OriginalValues[It]);
2175 }
2176 };
2177
2178 /// \brief Build a truncate instruction.
2179 class TruncBuilder : public TypePromotionAction {
2180 Value *Val;
2181
2182 public:
2183 /// \brief Build a truncate instruction of \p Opnd producing a \p Ty
2184 /// result.
2185 /// trunc Opnd to Ty.
2186 TruncBuilder(Instruction *Opnd, Type *Ty) : TypePromotionAction(Opnd) {
2187 IRBuilder<> Builder(Opnd);
2188 Val = Builder.CreateTrunc(Opnd, Ty, "promoted");
2189 DEBUG(dbgs() << "Do: TruncBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: TruncBuilder: " <<
*Val << "\n"; } } while (false)
;
2190 }
2191
2192 /// \brief Get the built value.
2193 Value *getBuiltValue() { return Val; }
2194
2195 /// \brief Remove the built instruction.
2196 void undo() override {
2197 DEBUG(dbgs() << "Undo: TruncBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: TruncBuilder: " <<
*Val << "\n"; } } while (false)
;
2198 if (Instruction *IVal = dyn_cast<Instruction>(Val))
2199 IVal->eraseFromParent();
2200 }
2201 };
2202
2203 /// \brief Build a sign extension instruction.
2204 class SExtBuilder : public TypePromotionAction {
2205 Value *Val;
2206
2207 public:
2208 /// \brief Build a sign extension instruction of \p Opnd producing a \p Ty
2209 /// result.
2210 /// sext Opnd to Ty.
2211 SExtBuilder(Instruction *InsertPt, Value *Opnd, Type *Ty)
2212 : TypePromotionAction(InsertPt) {
2213 IRBuilder<> Builder(InsertPt);
2214 Val = Builder.CreateSExt(Opnd, Ty, "promoted");
2215 DEBUG(dbgs() << "Do: SExtBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: SExtBuilder: " <<
*Val << "\n"; } } while (false)
;
2216 }
2217
2218 /// \brief Get the built value.
2219 Value *getBuiltValue() { return Val; }
2220
2221 /// \brief Remove the built instruction.
2222 void undo() override {
2223 DEBUG(dbgs() << "Undo: SExtBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: SExtBuilder: " <<
*Val << "\n"; } } while (false)
;
2224 if (Instruction *IVal = dyn_cast<Instruction>(Val))
2225 IVal->eraseFromParent();
2226 }
2227 };
2228
2229 /// \brief Build a zero extension instruction.
2230 class ZExtBuilder : public TypePromotionAction {
2231 Value *Val;
2232
2233 public:
2234 /// \brief Build a zero extension instruction of \p Opnd producing a \p Ty
2235 /// result.
2236 /// zext Opnd to Ty.
2237 ZExtBuilder(Instruction *InsertPt, Value *Opnd, Type *Ty)
2238 : TypePromotionAction(InsertPt) {
2239 IRBuilder<> Builder(InsertPt);
2240 Val = Builder.CreateZExt(Opnd, Ty, "promoted");
2241 DEBUG(dbgs() << "Do: ZExtBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: ZExtBuilder: " <<
*Val << "\n"; } } while (false)
;
2242 }
2243
2244 /// \brief Get the built value.
2245 Value *getBuiltValue() { return Val; }
2246
2247 /// \brief Remove the built instruction.
2248 void undo() override {
2249 DEBUG(dbgs() << "Undo: ZExtBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: ZExtBuilder: " <<
*Val << "\n"; } } while (false)
;
2250 if (Instruction *IVal = dyn_cast<Instruction>(Val))
2251 IVal->eraseFromParent();
2252 }
2253 };
2254
2255 /// \brief Mutate an instruction to another type.
2256 class TypeMutator : public TypePromotionAction {
2257 /// Record the original type.
2258 Type *OrigTy;
2259
2260 public:
2261 /// \brief Mutate the type of \p Inst into \p NewTy.
2262 TypeMutator(Instruction *Inst, Type *NewTy)
2263 : TypePromotionAction(Inst), OrigTy(Inst->getType()) {
2264 DEBUG(dbgs() << "Do: MutateType: " << *Inst << " with " << *NewTydo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: MutateType: " <<
*Inst << " with " << *NewTy << "\n"; } } while
(false)
2265 << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: MutateType: " <<
*Inst << " with " << *NewTy << "\n"; } } while
(false)
;
2266 Inst->mutateType(NewTy);
2267 }
2268
2269 /// \brief Mutate the instruction back to its original type.
2270 void undo() override {
2271 DEBUG(dbgs() << "Undo: MutateType: " << *Inst << " with " << *OrigTydo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: MutateType: " <<
*Inst << " with " << *OrigTy << "\n"; } } while
(false)
2272 << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: MutateType: " <<
*Inst << " with " << *OrigTy << "\n"; } } while
(false)
;
2273 Inst->mutateType(OrigTy);
2274 }
2275 };
2276
2277 /// \brief Replace the uses of an instruction by another instruction.
2278 class UsesReplacer : public TypePromotionAction {
2279 /// Helper structure to keep track of the replaced uses.
2280 struct InstructionAndIdx {
2281 /// The instruction using the instruction.
2282 Instruction *Inst;
2283
2284 /// The index where this instruction is used for Inst.
2285 unsigned Idx;
2286
2287 InstructionAndIdx(Instruction *Inst, unsigned Idx)
2288 : Inst(Inst), Idx(Idx) {}
2289 };
2290
2291 /// Keep track of the original uses (pair Instruction, Index).
2292 SmallVector<InstructionAndIdx, 4> OriginalUses;
2293
2294 using use_iterator = SmallVectorImpl<InstructionAndIdx>::iterator;
2295
2296 public:
2297 /// \brief Replace all the use of \p Inst by \p New.
2298 UsesReplacer(Instruction *Inst, Value *New) : TypePromotionAction(Inst) {
2299 DEBUG(dbgs() << "Do: UsersReplacer: " << *Inst << " with " << *Newdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: UsersReplacer: " <<
*Inst << " with " << *New << "\n"; } } while
(false)
2300 << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: UsersReplacer: " <<
*Inst << " with " << *New << "\n"; } } while
(false)
;
2301 // Record the original uses.
2302 for (Use &U : Inst->uses()) {
2303 Instruction *UserI = cast<Instruction>(U.getUser());
2304 OriginalUses.push_back(InstructionAndIdx(UserI, U.getOperandNo()));
2305 }
2306 // Now, we can replace the uses.
2307 Inst->replaceAllUsesWith(New);
2308 }
2309
2310 /// \brief Reassign the original uses of Inst to Inst.
2311 void undo() override {
2312 DEBUG(dbgs() << "Undo: UsersReplacer: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: UsersReplacer: "
<< *Inst << "\n"; } } while (false)
;
2313 for (use_iterator UseIt = OriginalUses.begin(),
2314 EndIt = OriginalUses.end();
2315 UseIt != EndIt; ++UseIt) {
2316 UseIt->Inst->setOperand(UseIt->Idx, Inst);
2317 }
2318 }
2319 };
2320
2321 /// \brief Remove an instruction from the IR.
2322 class InstructionRemover : public TypePromotionAction {
2323 /// Original position of the instruction.
2324 InsertionHandler Inserter;
2325
2326 /// Helper structure to hide all the link to the instruction. In other
2327 /// words, this helps to do as if the instruction was removed.
2328 OperandsHider Hider;
2329
2330 /// Keep track of the uses replaced, if any.
2331 UsesReplacer *Replacer = nullptr;
2332
2333 /// Keep track of instructions removed.
2334 SetOfInstrs &RemovedInsts;
2335
2336 public:
2337 /// \brief Remove all reference of \p Inst and optinally replace all its
2338 /// uses with New.
2339 /// \p RemovedInsts Keep track of the instructions removed by this Action.
2340 /// \pre If !Inst->use_empty(), then New != nullptr
2341 InstructionRemover(Instruction *Inst, SetOfInstrs &RemovedInsts,
2342 Value *New = nullptr)
2343 : TypePromotionAction(Inst), Inserter(Inst), Hider(Inst),
2344 RemovedInsts(RemovedInsts) {
2345 if (New)
2346 Replacer = new UsesReplacer(Inst, New);
2347 DEBUG(dbgs() << "Do: InstructionRemover: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: InstructionRemover: "
<< *Inst << "\n"; } } while (false)
;
2348 RemovedInsts.insert(Inst);
2349 /// The instructions removed here will be freed after completing
2350 /// optimizeBlock() for all blocks as we need to keep track of the
2351 /// removed instructions during promotion.
2352 Inst->removeFromParent();
2353 }
2354
2355 ~InstructionRemover() override { delete Replacer; }
2356
2357 /// \brief Resurrect the instruction and reassign it to the proper uses if
2358 /// new value was provided when build this action.
2359 void undo() override {
2360 DEBUG(dbgs() << "Undo: InstructionRemover: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: InstructionRemover: "
<< *Inst << "\n"; } } while (false)
;
2361 Inserter.insert(Inst);
2362 if (Replacer)
2363 Replacer->undo();
2364 Hider.undo();
2365 RemovedInsts.erase(Inst);
2366 }
2367 };
2368
2369public:
2370 /// Restoration point.
2371 /// The restoration point is a pointer to an action instead of an iterator
2372 /// because the iterator may be invalidated but not the pointer.
2373 using ConstRestorationPt = const TypePromotionAction *;
2374
2375 TypePromotionTransaction(SetOfInstrs &RemovedInsts)
2376 : RemovedInsts(RemovedInsts) {}
2377
2378 /// Advocate every changes made in that transaction.
2379 void commit();
2380
2381 /// Undo all the changes made after the given point.
2382 void rollback(ConstRestorationPt Point);
2383
2384 /// Get the current restoration point.
2385 ConstRestorationPt getRestorationPoint() const;
2386
2387 /// \name API for IR modification with state keeping to support rollback.
2388 /// @{
2389 /// Same as Instruction::setOperand.
2390 void setOperand(Instruction *Inst, unsigned Idx, Value *NewVal);
2391
2392 /// Same as Instruction::eraseFromParent.
2393 void eraseInstruction(Instruction *Inst, Value *NewVal = nullptr);
2394
2395 /// Same as Value::replaceAllUsesWith.
2396 void replaceAllUsesWith(Instruction *Inst, Value *New);
2397
2398 /// Same as Value::mutateType.
2399 void mutateType(Instruction *Inst, Type *NewTy);
2400
2401 /// Same as IRBuilder::createTrunc.
2402 Value *createTrunc(Instruction *Opnd, Type *Ty);
2403
2404 /// Same as IRBuilder::createSExt.
2405 Value *createSExt(Instruction *Inst, Value *Opnd, Type *Ty);
2406
2407 /// Same as IRBuilder::createZExt.
2408 Value *createZExt(Instruction *Inst, Value *Opnd, Type *Ty);
2409
2410 /// Same as Instruction::moveBefore.
2411 void moveBefore(Instruction *Inst, Instruction *Before);
2412 /// @}
2413
2414private:
2415 /// The ordered list of actions made so far.
2416 SmallVector<std::unique_ptr<TypePromotionAction>, 16> Actions;
2417
2418 using CommitPt = SmallVectorImpl<std::unique_ptr<TypePromotionAction>>::iterator;
2419
2420 SetOfInstrs &RemovedInsts;
2421};
2422
2423} // end anonymous namespace
2424
2425void TypePromotionTransaction::setOperand(Instruction *Inst, unsigned Idx,
2426 Value *NewVal) {
2427 Actions.push_back(llvm::make_unique<TypePromotionTransaction::OperandSetter>(
2428 Inst, Idx, NewVal));
2429}
2430
2431void TypePromotionTransaction::eraseInstruction(Instruction *Inst,
2432 Value *NewVal) {
2433 Actions.push_back(
2434 llvm::make_unique<TypePromotionTransaction::InstructionRemover>(
2435 Inst, RemovedInsts, NewVal));
2436}
2437
2438void TypePromotionTransaction::replaceAllUsesWith(Instruction *Inst,
2439 Value *New) {
2440 Actions.push_back(
2441 llvm::make_unique<TypePromotionTransaction::UsesReplacer>(Inst, New));
2442}
2443
2444void TypePromotionTransaction::mutateType(Instruction *Inst, Type *NewTy) {
2445 Actions.push_back(
2446 llvm::make_unique<TypePromotionTransaction::TypeMutator>(Inst, NewTy));
2447}
2448
2449Value *TypePromotionTransaction::createTrunc(Instruction *Opnd,
2450 Type *Ty) {
2451 std::unique_ptr<TruncBuilder> Ptr(new TruncBuilder(Opnd, Ty));
2452 Value *Val = Ptr->getBuiltValue();
2453 Actions.push_back(std::move(Ptr));
2454 return Val;
2455}
2456
2457Value *TypePromotionTransaction::createSExt(Instruction *Inst,
2458 Value *Opnd, Type *Ty) {
2459 std::unique_ptr<SExtBuilder> Ptr(new SExtBuilder(Inst, Opnd, Ty));
2460 Value *Val = Ptr->getBuiltValue();
2461 Actions.push_back(std::move(Ptr));
2462 return Val;
2463}
2464
2465Value *TypePromotionTransaction::createZExt(Instruction *Inst,
2466 Value *Opnd, Type *Ty) {
2467 std::unique_ptr<ZExtBuilder> Ptr(new ZExtBuilder(Inst, Opnd, Ty));
2468 Value *Val = Ptr->getBuiltValue();
2469 Actions.push_back(std::move(Ptr));
2470 return Val;
2471}
2472
2473void TypePromotionTransaction::moveBefore(Instruction *Inst,
2474 Instruction *Before) {
2475 Actions.push_back(
2476 llvm::make_unique<TypePromotionTransaction::InstructionMoveBefore>(
2477 Inst, Before));
2478}
2479
2480TypePromotionTransaction::ConstRestorationPt
2481TypePromotionTransaction::getRestorationPoint() const {
2482 return !Actions.empty() ? Actions.back().get() : nullptr;
2483}
2484
2485void TypePromotionTransaction::commit() {
2486 for (CommitPt It = Actions.begin(), EndIt = Actions.end(); It != EndIt;
2487 ++It)
2488 (*It)->commit();
2489 Actions.clear();
2490}
2491
2492void TypePromotionTransaction::rollback(
2493 TypePromotionTransaction::ConstRestorationPt Point) {
2494 while (!Actions.empty() && Point != Actions.back().get()) {
2495 std::unique_ptr<TypePromotionAction> Curr = Actions.pop_back_val();
2496 Curr->undo();
2497 }
2498}
2499
2500namespace {
2501
2502/// \brief A helper class for matching addressing modes.
2503///
2504/// This encapsulates the logic for matching the target-legal addressing modes.
2505class AddressingModeMatcher {
2506 SmallVectorImpl<Instruction*> &AddrModeInsts;
2507 const TargetLowering &TLI;
2508 const TargetRegisterInfo &TRI;
2509 const DataLayout &DL;
2510
2511 /// AccessTy/MemoryInst - This is the type for the access (e.g. double) and
2512 /// the memory instruction that we're computing this address for.
2513 Type *AccessTy;
2514 unsigned AddrSpace;
2515 Instruction *MemoryInst;
2516
2517 /// This is the addressing mode that we're building up. This is
2518 /// part of the return value of this addressing mode matching stuff.
2519 ExtAddrMode &AddrMode;
2520
2521 /// The instructions inserted by other CodeGenPrepare optimizations.
2522 const SetOfInstrs &InsertedInsts;
2523
2524 /// A map from the instructions to their type before promotion.
2525 InstrToOrigTy &PromotedInsts;
2526
2527 /// The ongoing transaction where every action should be registered.
2528 TypePromotionTransaction &TPT;
2529
2530 /// This is set to true when we should not do profitability checks.
2531 /// When true, IsProfitableToFoldIntoAddressingMode always returns true.
2532 bool IgnoreProfitability;
2533
2534 AddressingModeMatcher(SmallVectorImpl<Instruction *> &AMI,
2535 const TargetLowering &TLI,
2536 const TargetRegisterInfo &TRI,
2537 Type *AT, unsigned AS,
2538 Instruction *MI, ExtAddrMode &AM,
2539 const SetOfInstrs &InsertedInsts,
2540 InstrToOrigTy &PromotedInsts,
2541 TypePromotionTransaction &TPT)
2542 : AddrModeInsts(AMI), TLI(TLI), TRI(TRI),
2543 DL(MI->getModule()->getDataLayout()), AccessTy(AT), AddrSpace(AS),
2544 MemoryInst(MI), AddrMode(AM), InsertedInsts(InsertedInsts),
2545 PromotedInsts(PromotedInsts), TPT(TPT) {
2546 IgnoreProfitability = false;
2547 }
2548
2549public:
2550 /// Find the maximal addressing mode that a load/store of V can fold,
2551 /// give an access type of AccessTy. This returns a list of involved
2552 /// instructions in AddrModeInsts.
2553 /// \p InsertedInsts The instructions inserted by other CodeGenPrepare
2554 /// optimizations.
2555 /// \p PromotedInsts maps the instructions to their type before promotion.
2556 /// \p The ongoing transaction where every action should be registered.
2557 static ExtAddrMode Match(Value *V, Type *AccessTy, unsigned AS,
2558 Instruction *MemoryInst,
2559 SmallVectorImpl<Instruction*> &AddrModeInsts,
2560 const TargetLowering &TLI,
2561 const TargetRegisterInfo &TRI,
2562 const SetOfInstrs &InsertedInsts,
2563 InstrToOrigTy &PromotedInsts,
2564 TypePromotionTransaction &TPT) {
2565 ExtAddrMode Result;
2566
2567 bool Success = AddressingModeMatcher(AddrModeInsts, TLI, TRI,
2568 AccessTy, AS,
2569 MemoryInst, Result, InsertedInsts,
2570 PromotedInsts, TPT).matchAddr(V, 0);
2571 (void)Success; assert(Success && "Couldn't select *anything*?")(static_cast <bool> (Success && "Couldn't select *anything*?"
) ? void (0) : __assert_fail ("Success && \"Couldn't select *anything*?\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 2571, __extension__ __PRETTY_FUNCTION__))
;
2572 return Result;
2573 }
2574
2575private:
2576 bool matchScaledValue(Value *ScaleReg, int64_t Scale, unsigned Depth);
2577 bool matchAddr(Value *V, unsigned Depth);
2578 bool matchOperationAddr(User *Operation, unsigned Opcode, unsigned Depth,
2579 bool *MovedAway = nullptr);
2580 bool isProfitableToFoldIntoAddressingMode(Instruction *I,
2581 ExtAddrMode &AMBefore,
2582 ExtAddrMode &AMAfter);
2583 bool valueAlreadyLiveAtInst(Value *Val, Value *KnownLive1, Value *KnownLive2);
2584 bool isPromotionProfitable(unsigned NewCost, unsigned OldCost,
2585 Value *PromotedOperand) const;
2586};
2587
2588/// \brief Keep track of simplification of Phi nodes.
2589/// Accept the set of all phi nodes and erase phi node from this set
2590/// if it is simplified.
2591class SimplificationTracker {
2592 DenseMap<Value *, Value *> Storage;
2593 const SimplifyQuery &SQ;
2594 // Tracks newly created Phi nodes. We use a SetVector to get deterministic
2595 // order when iterating over the set in MatchPhiSet.
2596 SmallSetVector<PHINode *, 32> AllPhiNodes;
2597 // Tracks newly created Select nodes.
2598 SmallPtrSet<SelectInst *, 32> AllSelectNodes;
2599
2600public:
2601 SimplificationTracker(const SimplifyQuery &sq)
2602 : SQ(sq) {}
2603
2604 Value *Get(Value *V) {
2605 do {
2606 auto SV = Storage.find(V);
2607 if (SV == Storage.end())
2608 return V;
2609 V = SV->second;
2610 } while (true);
2611 }
2612
2613 Value *Simplify(Value *Val) {
2614 SmallVector<Value *, 32> WorkList;
2615 SmallPtrSet<Value *, 32> Visited;
2616 WorkList.push_back(Val);
2617 while (!WorkList.empty()) {
2618 auto P = WorkList.pop_back_val();
2619 if (!Visited.insert(P).second)
2620 continue;
2621 if (auto *PI = dyn_cast<Instruction>(P))
2622 if (Value *V = SimplifyInstruction(cast<Instruction>(PI), SQ)) {
2623 for (auto *U : PI->users())
2624 WorkList.push_back(cast<Value>(U));
2625 Put(PI, V);
2626 PI->replaceAllUsesWith(V);
2627 if (auto *PHI = dyn_cast<PHINode>(PI))
2628 AllPhiNodes.remove(PHI);
2629 if (auto *Select = dyn_cast<SelectInst>(PI))
2630 AllSelectNodes.erase(Select);
2631 PI->eraseFromParent();
2632 }
2633 }
2634 return Get(Val);
2635 }
2636
2637 void Put(Value *From, Value *To) {
2638 Storage.insert({ From, To });
2639 }
2640
2641 void ReplacePhi(PHINode *From, PHINode *To) {
2642 Value* OldReplacement = Get(From);
2643 while (OldReplacement != From) {
2644 From = To;
2645 To = dyn_cast<PHINode>(OldReplacement);
2646 OldReplacement = Get(From);
2647 }
2648 assert(Get(To) == To && "Replacement PHI node is already replaced.")(static_cast <bool> (Get(To) == To && "Replacement PHI node is already replaced."
) ? void (0) : __assert_fail ("Get(To) == To && \"Replacement PHI node is already replaced.\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 2648, __extension__ __PRETTY_FUNCTION__))
;
2649 Put(From, To);
2650 From->replaceAllUsesWith(To);
2651 AllPhiNodes.remove(From);
2652 From->eraseFromParent();
2653 }
2654
2655 SmallSetVector<PHINode *, 32>& newPhiNodes() { return AllPhiNodes; }
2656
2657 void insertNewPhi(PHINode *PN) { AllPhiNodes.insert(PN); }
2658
2659 void insertNewSelect(SelectInst *SI) { AllSelectNodes.insert(SI); }
2660
2661 unsigned countNewPhiNodes() const { return AllPhiNodes.size(); }
2662
2663 unsigned countNewSelectNodes() const { return AllSelectNodes.size(); }
2664
2665 void destroyNewNodes(Type *CommonType) {
2666 // For safe erasing, replace the uses with dummy value first.
2667 auto Dummy = UndefValue::get(CommonType);
2668 for (auto I : AllPhiNodes) {
2669 I->replaceAllUsesWith(Dummy);
2670 I->eraseFromParent();
2671 }
2672 AllPhiNodes.clear();
2673 for (auto I : AllSelectNodes) {
2674 I->replaceAllUsesWith(Dummy);
2675 I->eraseFromParent();
2676 }
2677 AllSelectNodes.clear();
2678 }
2679};
2680
2681/// \brief A helper class for combining addressing modes.
2682class AddressingModeCombiner {
2683 typedef std::pair<Value *, BasicBlock *> ValueInBB;
2684 typedef DenseMap<ValueInBB, Value *> FoldAddrToValueMapping;
2685 typedef std::pair<PHINode *, PHINode *> PHIPair;
2686
2687private:
2688 /// The addressing modes we've collected.
2689 SmallVector<ExtAddrMode, 16> AddrModes;
2690
2691 /// The field in which the AddrModes differ, when we have more than one.
2692 ExtAddrMode::FieldName DifferentField = ExtAddrMode::NoField;
2693
2694 /// Are the AddrModes that we have all just equal to their original values?
2695 bool AllAddrModesTrivial = true;
2696
2697 /// Common Type for all different fields in addressing modes.
2698 Type *CommonType;
2699
2700 /// SimplifyQuery for simplifyInstruction utility.
2701 const SimplifyQuery &SQ;
2702
2703 /// Original Address.
2704 ValueInBB Original;
2705
2706public:
2707 AddressingModeCombiner(const SimplifyQuery &_SQ, ValueInBB OriginalValue)
2708 : CommonType(nullptr), SQ(_SQ), Original(OriginalValue) {}
2709
2710 /// \brief Get the combined AddrMode
2711 const ExtAddrMode &getAddrMode() const {
2712 return AddrModes[0];
2713 }
2714
2715 /// \brief Add a new AddrMode if it's compatible with the AddrModes we already
2716 /// have.
2717 /// \return True iff we succeeded in doing so.
2718 bool addNewAddrMode(ExtAddrMode &NewAddrMode) {
2719 // Take note of if we have any non-trivial AddrModes, as we need to detect
2720 // when all AddrModes are trivial as then we would introduce a phi or select
2721 // which just duplicates what's already there.
2722 AllAddrModesTrivial = AllAddrModesTrivial && NewAddrMode.isTrivial();
2723
2724 // If this is the first addrmode then everything is fine.
2725 if (AddrModes.empty()) {
2726 AddrModes.emplace_back(NewAddrMode);
2727 return true;
2728 }
2729
2730 // Figure out how different this is from the other address modes, which we
2731 // can do just by comparing against the first one given that we only care
2732 // about the cumulative difference.
2733 ExtAddrMode::FieldName ThisDifferentField =
2734 AddrModes[0].compare(NewAddrMode);
2735 if (DifferentField == ExtAddrMode::NoField)
2736 DifferentField = ThisDifferentField;
2737 else if (DifferentField != ThisDifferentField)
2738 DifferentField = ExtAddrMode::MultipleFields;
2739
2740 // If NewAddrMode differs in more than one dimension we cannot handle it.
2741 bool CanHandle = DifferentField != ExtAddrMode::MultipleFields;
2742
2743 // If Scale Field is different then we reject.
2744 CanHandle = CanHandle && DifferentField != ExtAddrMode::ScaleField;
2745
2746 // We also must reject the case when base offset is different and
2747 // scale reg is not null, we cannot handle this case due to merge of
2748 // different offsets will be used as ScaleReg.
2749 CanHandle = CanHandle && (DifferentField != ExtAddrMode::BaseOffsField ||
2750 !NewAddrMode.ScaledReg);
2751
2752 // We also must reject the case when GV is different and BaseReg installed
2753 // due to we want to use base reg as a merge of GV values.
2754 CanHandle = CanHandle && (DifferentField != ExtAddrMode::BaseGVField ||
2755 !NewAddrMode.HasBaseReg);
2756
2757 // Even if NewAddMode is the same we still need to collect it due to
2758 // original value is different. And later we will need all original values
2759 // as anchors during finding the common Phi node.
2760 if (CanHandle)
2761 AddrModes.emplace_back(NewAddrMode);
2762 else
2763 AddrModes.clear();
2764
2765 return CanHandle;
2766 }
2767
2768 /// \brief Combine the addressing modes we've collected into a single
2769 /// addressing mode.
2770 /// \return True iff we successfully combined them or we only had one so
2771 /// didn't need to combine them anyway.
2772 bool combineAddrModes() {
2773 // If we have no AddrModes then they can't be combined.
2774 if (AddrModes.size() == 0)
2775 return false;
2776
2777 // A single AddrMode can trivially be combined.
2778 if (AddrModes.size() == 1 || DifferentField == ExtAddrMode::NoField)
2779 return true;
2780
2781 // If the AddrModes we collected are all just equal to the value they are
2782 // derived from then combining them wouldn't do anything useful.
2783 if (AllAddrModesTrivial)
2784 return false;
2785
2786 if (!addrModeCombiningAllowed())
2787 return false;
2788
2789 // Build a map between <original value, basic block where we saw it> to
2790 // value of base register.
2791 // Bail out if there is no common type.
2792 FoldAddrToValueMapping Map;
2793 if (!initializeMap(Map))
2794 return false;
2795
2796 Value *CommonValue = findCommon(Map);
2797 if (CommonValue)
2798 AddrModes[0].SetCombinedField(DifferentField, CommonValue, AddrModes);
2799 return CommonValue != nullptr;
2800 }
2801
2802private:
2803 /// \brief Initialize Map with anchor values. For address seen in some BB
2804 /// we set the value of different field saw in this address.
2805 /// If address is not an instruction than basic block is set to null.
2806 /// At the same time we find a common type for different field we will
2807 /// use to create new Phi/Select nodes. Keep it in CommonType field.
2808 /// Return false if there is no common type found.
2809 bool initializeMap(FoldAddrToValueMapping &Map) {
2810 // Keep track of keys where the value is null. We will need to replace it
2811 // with constant null when we know the common type.
2812 SmallVector<ValueInBB, 2> NullValue;
2813 Type *IntPtrTy = SQ.DL.getIntPtrType(AddrModes[0].OriginalValue->getType());
2814 for (auto &AM : AddrModes) {
2815 BasicBlock *BB = nullptr;
2816 if (Instruction *I = dyn_cast<Instruction>(AM.OriginalValue))
2817 BB = I->getParent();
2818
2819 Value *DV = AM.GetFieldAsValue(DifferentField, IntPtrTy);
2820 if (DV) {
2821 auto *Type = DV->getType();
2822 if (CommonType && CommonType != Type)
2823 return false;
2824 CommonType = Type;
2825 Map[{ AM.OriginalValue, BB }] = DV;
2826 } else {
2827 NullValue.push_back({ AM.OriginalValue, BB });
2828 }
2829 }
2830 assert(CommonType && "At least one non-null value must be!")(static_cast <bool> (CommonType && "At least one non-null value must be!"
) ? void (0) : __assert_fail ("CommonType && \"At least one non-null value must be!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 2830, __extension__ __PRETTY_FUNCTION__))
;
2831 for (auto VIBB : NullValue)
2832 Map[VIBB] = Constant::getNullValue(CommonType);
2833 return true;
2834 }
2835
2836 /// \brief We have mapping between value A and basic block where value A
2837 /// seen to other value B where B was a field in addressing mode represented
2838 /// by A. Also we have an original value C representin an address in some
2839 /// basic block. Traversing from C through phi and selects we ended up with
2840 /// A's in a map. This utility function tries to find a value V which is a
2841 /// field in addressing mode C and traversing through phi nodes and selects
2842 /// we will end up in corresponded values B in a map.
2843 /// The utility will create a new Phi/Selects if needed.
2844 // The simple example looks as follows:
2845 // BB1:
2846 // p1 = b1 + 40
2847 // br cond BB2, BB3
2848 // BB2:
2849 // p2 = b2 + 40
2850 // br BB3
2851 // BB3:
2852 // p = phi [p1, BB1], [p2, BB2]
2853 // v = load p
2854 // Map is
2855 // <p1, BB1> -> b1
2856 // <p2, BB2> -> b2
2857 // Request is
2858 // <p, BB3> -> ?
2859 // The function tries to find or build phi [b1, BB1], [b2, BB2] in BB3
2860 Value *findCommon(FoldAddrToValueMapping &Map) {
2861 // Tracks the simplification of newly created phi nodes. The reason we use
2862 // this mapping is because we will add new created Phi nodes in AddrToBase.
2863 // Simplification of Phi nodes is recursive, so some Phi node may
2864 // be simplified after we added it to AddrToBase.
2865 // Using this mapping we can find the current value in AddrToBase.
2866 SimplificationTracker ST(SQ);
2867
2868 // First step, DFS to create PHI nodes for all intermediate blocks.
2869 // Also fill traverse order for the second step.
2870 SmallVector<ValueInBB, 32> TraverseOrder;
2871 InsertPlaceholders(Map, TraverseOrder, ST);
2872
2873 // Second Step, fill new nodes by merged values and simplify if possible.
2874 FillPlaceholders(Map, TraverseOrder, ST);
2875
2876 if (!AddrSinkNewSelects && ST.countNewSelectNodes() > 0) {
2877 ST.destroyNewNodes(CommonType);
2878 return nullptr;
2879 }
2880
2881 // Now we'd like to match New Phi nodes to existed ones.
2882 unsigned PhiNotMatchedCount = 0;
2883 if (!MatchPhiSet(ST, AddrSinkNewPhis, PhiNotMatchedCount)) {
2884 ST.destroyNewNodes(CommonType);
2885 return nullptr;
2886 }
2887
2888 auto *Result = ST.Get(Map.find(Original)->second);
2889 if (Result) {
2890 NumMemoryInstsPhiCreated += ST.countNewPhiNodes() + PhiNotMatchedCount;
2891 NumMemoryInstsSelectCreated += ST.countNewSelectNodes();
2892 }
2893 return Result;
2894 }
2895
2896 /// \brief Try to match PHI node to Candidate.
2897 /// Matcher tracks the matched Phi nodes.
2898 bool MatchPhiNode(PHINode *PHI, PHINode *Candidate,
2899 SmallSetVector<PHIPair, 8> &Matcher,
2900 SmallSetVector<PHINode *, 32> &PhiNodesToMatch) {
2901 SmallVector<PHIPair, 8> WorkList;
2902 Matcher.insert({ PHI, Candidate });
2903 WorkList.push_back({ PHI, Candidate });
2904 SmallSet<PHIPair, 8> Visited;
2905 while (!WorkList.empty()) {
2906 auto Item = WorkList.pop_back_val();
2907 if (!Visited.insert(Item).second)
2908 continue;
2909 // We iterate over all incoming values to Phi to compare them.
2910 // If values are different and both of them Phi and the first one is a
2911 // Phi we added (subject to match) and both of them is in the same basic
2912 // block then we can match our pair if values match. So we state that
2913 // these values match and add it to work list to verify that.
2914 for (auto B : Item.first->blocks()) {
2915 Value *FirstValue = Item.first->getIncomingValueForBlock(B);
2916 Value *SecondValue = Item.second->getIncomingValueForBlock(B);
2917 if (FirstValue == SecondValue)
2918 continue;
2919
2920 PHINode *FirstPhi = dyn_cast<PHINode>(FirstValue);
2921 PHINode *SecondPhi = dyn_cast<PHINode>(SecondValue);
2922
2923 // One of them is not Phi or
2924 // The first one is not Phi node from the set we'd like to match or
2925 // Phi nodes from different basic blocks then
2926 // we will not be able to match.
2927 if (!FirstPhi || !SecondPhi || !PhiNodesToMatch.count(FirstPhi) ||
2928 FirstPhi->getParent() != SecondPhi->getParent())
2929 return false;
2930
2931 // If we already matched them then continue.
2932 if (Matcher.count({ FirstPhi, SecondPhi }))
2933 continue;
2934 // So the values are different and does not match. So we need them to
2935 // match.
2936 Matcher.insert({ FirstPhi, SecondPhi });
2937 // But me must check it.
2938 WorkList.push_back({ FirstPhi, SecondPhi });
2939 }
2940 }
2941 return true;
2942 }
2943
2944 /// \brief For the given set of PHI nodes (in the SimplificationTracker) try
2945 /// to find their equivalents.
2946 /// Returns false if this matching fails and creation of new Phi is disabled.
2947 bool MatchPhiSet(SimplificationTracker &ST, bool AllowNewPhiNodes,
2948 unsigned &PhiNotMatchedCount) {
2949 // Use a SetVector for Matched to make sure we do replacements (ReplacePhi)
2950 // in a deterministic order below.
2951 SmallSetVector<PHIPair, 8> Matched;
2952 SmallPtrSet<PHINode *, 8> WillNotMatch;
2953 SmallSetVector<PHINode *, 32> &PhiNodesToMatch = ST.newPhiNodes();
2954 while (PhiNodesToMatch.size()) {
2955 PHINode *PHI = *PhiNodesToMatch.begin();
2956
2957 // Add us, if no Phi nodes in the basic block we do not match.
2958 WillNotMatch.clear();
2959 WillNotMatch.insert(PHI);
2960
2961 // Traverse all Phis until we found equivalent or fail to do that.
2962 bool IsMatched = false;
2963 for (auto &P : PHI->getParent()->phis()) {
2964 if (&P == PHI)
2965 continue;
2966 if ((IsMatched = MatchPhiNode(PHI, &P, Matched, PhiNodesToMatch)))
2967 break;
2968 // If it does not match, collect all Phi nodes from matcher.
2969 // if we end up with no match, them all these Phi nodes will not match
2970 // later.
2971 for (auto M : Matched)
2972 WillNotMatch.insert(M.first);
2973 Matched.clear();
2974 }
2975 if (IsMatched) {
2976 // Replace all matched values and erase them.
2977 for (auto MV : Matched)
2978 ST.ReplacePhi(MV.first, MV.second);
2979 Matched.clear();
2980 continue;
2981 }
2982 // If we are not allowed to create new nodes then bail out.
2983 if (!AllowNewPhiNodes)
2984 return false;
2985 // Just remove all seen values in matcher. They will not match anything.
2986 PhiNotMatchedCount += WillNotMatch.size();
2987 for (auto *P : WillNotMatch)
2988 PhiNodesToMatch.remove(P);
2989 }
2990 return true;
2991 }
2992 /// \brief Fill the placeholder with values from predecessors and simplify it.
2993 void FillPlaceholders(FoldAddrToValueMapping &Map,
2994 SmallVectorImpl<ValueInBB> &TraverseOrder,
2995 SimplificationTracker &ST) {
2996 while (!TraverseOrder.empty()) {
2997 auto Current = TraverseOrder.pop_back_val();
2998 assert(Map.find(Current) != Map.end() && "No node to fill!!!")(static_cast <bool> (Map.find(Current) != Map.end() &&
"No node to fill!!!") ? void (0) : __assert_fail ("Map.find(Current) != Map.end() && \"No node to fill!!!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 2998, __extension__ __PRETTY_FUNCTION__))
;
2999 Value *CurrentValue = Current.first;
3000 BasicBlock *CurrentBlock = Current.second;
3001 Value *V = Map[Current];
3002
3003 if (SelectInst *Select = dyn_cast<SelectInst>(V)) {
3004 // CurrentValue also must be Select.
3005 auto *CurrentSelect = cast<SelectInst>(CurrentValue);
3006 auto *TrueValue = CurrentSelect->getTrueValue();
3007 ValueInBB TrueItem = { TrueValue, isa<Instruction>(TrueValue)
3008 ? CurrentBlock
3009 : nullptr };
3010 assert(Map.find(TrueItem) != Map.end() && "No True Value!")(static_cast <bool> (Map.find(TrueItem) != Map.end() &&
"No True Value!") ? void (0) : __assert_fail ("Map.find(TrueItem) != Map.end() && \"No True Value!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 3010, __extension__ __PRETTY_FUNCTION__))
;
3011 Select->setTrueValue(ST.Get(Map[TrueItem]));
3012 auto *FalseValue = CurrentSelect->getFalseValue();
3013 ValueInBB FalseItem = { FalseValue, isa<Instruction>(FalseValue)
3014 ? CurrentBlock
3015 : nullptr };
3016 assert(Map.find(FalseItem) != Map.end() && "No False Value!")(static_cast <bool> (Map.find(FalseItem) != Map.end() &&
"No False Value!") ? void (0) : __assert_fail ("Map.find(FalseItem) != Map.end() && \"No False Value!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 3016, __extension__ __PRETTY_FUNCTION__))
;
3017 Select->setFalseValue(ST.Get(Map[FalseItem]));
3018 } else {
3019 // Must be a Phi node then.
3020 PHINode *PHI = cast<PHINode>(V);
3021 // Fill the Phi node with values from predecessors.
3022 bool IsDefinedInThisBB =
3023 cast<Instruction>(CurrentValue)->getParent() == CurrentBlock;
3024 auto *CurrentPhi = dyn_cast<PHINode>(CurrentValue);
3025 for (auto B : predecessors(CurrentBlock)) {
3026 Value *PV = IsDefinedInThisBB
3027 ? CurrentPhi->getIncomingValueForBlock(B)
3028 : CurrentValue;
3029 ValueInBB item = { PV, isa<Instruction>(PV) ? B : nullptr };
3030 assert(Map.find(item) != Map.end() && "No predecessor Value!")(static_cast <bool> (Map.find(item) != Map.end() &&
"No predecessor Value!") ? void (0) : __assert_fail ("Map.find(item) != Map.end() && \"No predecessor Value!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 3030, __extension__ __PRETTY_FUNCTION__))
;
3031 PHI->addIncoming(ST.Get(Map[item]), B);
3032 }
3033 }
3034 // Simplify if possible.
3035 Map[Current] = ST.Simplify(V);
3036 }
3037 }
3038
3039 /// Starting from value recursively iterates over predecessors up to known
3040 /// ending values represented in a map. For each traversed block inserts
3041 /// a placeholder Phi or Select.
3042 /// Reports all new created Phi/Select nodes by adding them to set.
3043 /// Also reports and order in what basic blocks have been traversed.
3044 void InsertPlaceholders(FoldAddrToValueMapping &Map,
3045 SmallVectorImpl<ValueInBB> &TraverseOrder,
3046 SimplificationTracker &ST) {
3047 SmallVector<ValueInBB, 32> Worklist;
3048 assert((isa<PHINode>(Original.first) || isa<SelectInst>(Original.first)) &&(static_cast <bool> ((isa<PHINode>(Original.first
) || isa<SelectInst>(Original.first)) && "Address must be a Phi or Select node"
) ? void (0) : __assert_fail ("(isa<PHINode>(Original.first) || isa<SelectInst>(Original.first)) && \"Address must be a Phi or Select node\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 3049, __extension__ __PRETTY_FUNCTION__))
3049 "Address must be a Phi or Select node")(static_cast <bool> ((isa<PHINode>(Original.first
) || isa<SelectInst>(Original.first)) && "Address must be a Phi or Select node"
) ? void (0) : __assert_fail ("(isa<PHINode>(Original.first) || isa<SelectInst>(Original.first)) && \"Address must be a Phi or Select node\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 3049, __extension__ __PRETTY_FUNCTION__))
;
3050 auto *Dummy = UndefValue::get(CommonType);
3051 Worklist.push_back(Original);
3052 while (!Worklist.empty()) {
3053 auto Current = Worklist.pop_back_val();
3054 // If value is not an instruction it is something global, constant,
3055 // parameter and we can say that this value is observable in any block.
3056 // Set block to null to denote it.
3057 // Also please take into account that it is how we build anchors.
3058 if (!isa<Instruction>(Current.first))
3059 Current.second = nullptr;
3060 // if it is already visited or it is an ending value then skip it.
3061 if (Map.find(Current) != Map.end())
3062 continue;
3063 TraverseOrder.push_back(Current);
3064
3065 Value *CurrentValue = Current.first;
3066 BasicBlock *CurrentBlock = Current.second;
3067 // CurrentValue must be a Phi node or select. All others must be covered
3068 // by anchors.
3069 Instruction *CurrentI = cast<Instruction>(CurrentValue);
3070 bool IsDefinedInThisBB = CurrentI->getParent() == CurrentBlock;
3071
3072 unsigned PredCount =
3073 std::distance(pred_begin(CurrentBlock), pred_end(CurrentBlock));
3074 // if Current Value is not defined in this basic block we are interested
3075 // in values in predecessors.
3076 if (!IsDefinedInThisBB) {
3077 assert(PredCount && "Unreachable block?!")(static_cast <bool> (PredCount && "Unreachable block?!"
) ? void (0) : __assert_fail ("PredCount && \"Unreachable block?!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 3077, __extension__ __PRETTY_FUNCTION__))
;
3078 PHINode *PHI = PHINode::Create(CommonType, PredCount, "sunk_phi",
3079 &CurrentBlock->front());
3080 Map[Current] = PHI;
3081 ST.insertNewPhi(PHI);
3082 // Add all predecessors in work list.
3083 for (auto B : predecessors(CurrentBlock))
3084 Worklist.push_back({ CurrentValue, B });
3085 continue;
3086 }
3087 // Value is defined in this basic block.
3088 if (SelectInst *OrigSelect = dyn_cast<SelectInst>(CurrentI)) {
3089 // Is it OK to get metadata from OrigSelect?!
3090 // Create a Select placeholder with dummy value.
3091 SelectInst *Select =
3092 SelectInst::Create(OrigSelect->getCondition(), Dummy, Dummy,
3093 OrigSelect->getName(), OrigSelect, OrigSelect);
3094 Map[Current] = Select;
3095 ST.insertNewSelect(Select);
3096 // We are interested in True and False value in this basic block.
3097 Worklist.push_back({ OrigSelect->getTrueValue(), CurrentBlock });
3098 Worklist.push_back({ OrigSelect->getFalseValue(), CurrentBlock });
3099 } else {
3100 // It must be a Phi node then.
3101 auto *CurrentPhi = cast<PHINode>(CurrentI);
3102 // Create new Phi node for merge of bases.
3103 assert(PredCount && "Unreachable block?!")(static_cast <bool> (PredCount && "Unreachable block?!"
) ? void (0) : __assert_fail ("PredCount && \"Unreachable block?!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 3103, __extension__ __PRETTY_FUNCTION__))
;
3104 PHINode *PHI = PHINode::Create(CommonType, PredCount, "sunk_phi",
3105 &CurrentBlock->front());
3106 Map[Current] = PHI;
3107 ST.insertNewPhi(PHI);
3108
3109 // Add all predecessors in work list.
3110 for (auto B : predecessors(CurrentBlock))
3111 Worklist.push_back({ CurrentPhi->getIncomingValueForBlock(B), B });
3112 }
3113 }
3114 }
3115
3116 bool addrModeCombiningAllowed() {
3117 if (DisableComplexAddrModes)
3118 return false;
3119 switch (DifferentField) {
3120 default:
3121 return false;
3122 case ExtAddrMode::BaseRegField:
3123 return AddrSinkCombineBaseReg;
3124 case ExtAddrMode::BaseGVField:
3125 return AddrSinkCombineBaseGV;
3126 case ExtAddrMode::BaseOffsField:
3127 return AddrSinkCombineBaseOffs;
3128 case ExtAddrMode::ScaledRegField:
3129 return AddrSinkCombineScaledReg;
3130 }
3131 }
3132};
3133} // end anonymous namespace
3134
3135/// Try adding ScaleReg*Scale to the current addressing mode.
3136/// Return true and update AddrMode if this addr mode is legal for the target,
3137/// false if not.
3138bool AddressingModeMatcher::matchScaledValue(Value *ScaleReg, int64_t Scale,
3139 unsigned Depth) {
3140 // If Scale is 1, then this is the same as adding ScaleReg to the addressing
3141 // mode. Just process that directly.
3142 if (Scale == 1)
3143 return matchAddr(ScaleReg, Depth);
3144
3145 // If the scale is 0, it takes nothing to add this.
3146 if (Scale == 0)
3147 return true;
3148
3149 // If we already have a scale of this value, we can add to it, otherwise, we
3150 // need an available scale field.
3151 if (AddrMode.Scale != 0 && AddrMode.ScaledReg != ScaleReg)
3152 return false;
3153
3154 ExtAddrMode TestAddrMode = AddrMode;
3155
3156 // Add scale to turn X*4+X*3 -> X*7. This could also do things like
3157 // [A+B + A*7] -> [B+A*8].
3158 TestAddrMode.Scale += Scale;
3159 TestAddrMode.ScaledReg = ScaleReg;
3160
3161 // If the new address isn't legal, bail out.
3162 if (!TLI.isLegalAddressingMode(DL, TestAddrMode, AccessTy, AddrSpace))
3163 return false;
3164
3165 // It was legal, so commit it.
3166 AddrMode = TestAddrMode;
3167
3168 // Okay, we decided that we can add ScaleReg+Scale to AddrMode. Check now
3169 // to see if ScaleReg is actually X+C. If so, we can turn this into adding
3170 // X*Scale + C*Scale to addr mode.
3171 ConstantInt *CI = nullptr; Value *AddLHS = nullptr;
3172 if (isa<Instruction>(ScaleReg) && // not a constant expr.
3173 match(ScaleReg, m_Add(m_Value(AddLHS), m_ConstantInt(CI)))) {
3174 TestAddrMode.ScaledReg = AddLHS;
3175 TestAddrMode.BaseOffs += CI->getSExtValue()*TestAddrMode.Scale;
3176
3177 // If this addressing mode is legal, commit it and remember that we folded
3178 // this instruction.
3179 if (TLI.isLegalAddressingMode(DL, TestAddrMode, AccessTy, AddrSpace)) {
3180 AddrModeInsts.push_back(cast<Instruction>(ScaleReg));
3181 AddrMode = TestAddrMode;
3182 return true;
3183 }
3184 }
3185
3186 // Otherwise, not (x+c)*scale, just return what we have.
3187 return true;
3188}
3189
3190/// This is a little filter, which returns true if an addressing computation
3191/// involving I might be folded into a load/store accessing it.
3192/// This doesn't need to be perfect, but needs to accept at least
3193/// the set of instructions that MatchOperationAddr can.
3194static bool MightBeFoldableInst(Instruction *I) {
3195 switch (I->getOpcode()) {
3196 case Instruction::BitCast:
3197 case Instruction::AddrSpaceCast:
3198 // Don't touch identity bitcasts.
3199 if (I->getType() == I->getOperand(0)->getType())
3200 return false;
3201 return I->getType()->isPointerTy() || I->getType()->isIntegerTy();
3202 case Instruction::PtrToInt:
3203 // PtrToInt is always a noop, as we know that the int type is pointer sized.
3204 return true;
3205 case Instruction::IntToPtr:
3206 // We know the input is intptr_t, so this is foldable.
3207 return true;
3208 case Instruction::Add:
3209 return true;
3210 case Instruction::Mul:
3211 case Instruction::Shl:
3212 // Can only handle X*C and X << C.
3213 return isa<ConstantInt>(I->getOperand(1));
3214 case Instruction::GetElementPtr:
3215 return true;
3216 default:
3217 return false;
3218 }
3219}
3220
3221/// \brief Check whether or not \p Val is a legal instruction for \p TLI.
3222/// \note \p Val is assumed to be the product of some type promotion.
3223/// Therefore if \p Val has an undefined state in \p TLI, this is assumed
3224/// to be legal, as the non-promoted value would have had the same state.
3225static bool isPromotedInstructionLegal(const TargetLowering &TLI,
3226 const DataLayout &DL, Value *Val) {
3227 Instruction *PromotedInst = dyn_cast<Instruction>(Val);
3228 if (!PromotedInst)
3229 return false;
3230 int ISDOpcode = TLI.InstructionOpcodeToISD(PromotedInst->getOpcode());
3231 // If the ISDOpcode is undefined, it was undefined before the promotion.
3232 if (!ISDOpcode)
3233 return true;
3234 // Otherwise, check if the promoted instruction is legal or not.
3235 return TLI.isOperationLegalOrCustom(
3236 ISDOpcode, TLI.getValueType(DL, PromotedInst->getType()));
3237}
3238
3239namespace {
3240
3241/// \brief Hepler class to perform type promotion.
3242class TypePromotionHelper {
3243 /// \brief Utility function to check whether or not a sign or zero extension
3244 /// of \p Inst with \p ConsideredExtType can be moved through \p Inst by
3245 /// either using the operands of \p Inst or promoting \p Inst.
3246 /// The type of the extension is defined by \p IsSExt.
3247 /// In other words, check if:
3248 /// ext (Ty Inst opnd1 opnd2 ... opndN) to ConsideredExtType.
3249 /// #1 Promotion applies:
3250 /// ConsideredExtType Inst (ext opnd1 to ConsideredExtType, ...).
3251 /// #2 Operand reuses:
3252 /// ext opnd1 to ConsideredExtType.
3253 /// \p PromotedInsts maps the instructions to their type before promotion.
3254 static bool canGetThrough(const Instruction *Inst, Type *ConsideredExtType,
3255 const InstrToOrigTy &PromotedInsts, bool IsSExt);
3256
3257 /// \brief Utility function to determine if \p OpIdx should be promoted when
3258 /// promoting \p Inst.
3259 static bool shouldExtOperand(const Instruction *Inst, int OpIdx) {
3260 return !(isa<SelectInst>(Inst) && OpIdx == 0);
3261 }
3262
3263 /// \brief Utility function to promote the operand of \p Ext when this
3264 /// operand is a promotable trunc or sext or zext.
3265 /// \p PromotedInsts maps the instructions to their type before promotion.
3266 /// \p CreatedInstsCost[out] contains the cost of all instructions
3267 /// created to promote the operand of Ext.
3268 /// Newly added extensions are inserted in \p Exts.
3269 /// Newly added truncates are inserted in \p Truncs.
3270 /// Should never be called directly.
3271 /// \return The promoted value which is used instead of Ext.
3272 static Value *promoteOperandForTruncAndAnyExt(
3273 Instruction *Ext, TypePromotionTransaction &TPT,
3274 InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
3275 SmallVectorImpl<Instruction *> *Exts,
3276 SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI);
3277
3278 /// \brief Utility function to promote the operand of \p Ext when this
3279 /// operand is promotable and is not a supported trunc or sext.
3280 /// \p PromotedInsts maps the instructions to their type before promotion.
3281 /// \p CreatedInstsCost[out] contains the cost of all the instructions
3282 /// created to promote the operand of Ext.
3283 /// Newly added extensions are inserted in \p Exts.
3284 /// Newly added truncates are inserted in \p Truncs.
3285 /// Should never be called directly.
3286 /// \return The promoted value which is used instead of Ext.
3287 static Value *promoteOperandForOther(Instruction *Ext,
3288 TypePromotionTransaction &TPT,
3289 InstrToOrigTy &PromotedInsts,
3290 unsigned &CreatedInstsCost,
3291 SmallVectorImpl<Instruction *> *Exts,
3292 SmallVectorImpl<Instruction *> *Truncs,
3293 const TargetLowering &TLI, bool IsSExt);
3294
3295 /// \see promoteOperandForOther.
3296 static Value *signExtendOperandForOther(
3297 Instruction *Ext, TypePromotionTransaction &TPT,
3298 InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
3299 SmallVectorImpl<Instruction *> *Exts,
3300 SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI) {
3301 return promoteOperandForOther(Ext, TPT, PromotedInsts, CreatedInstsCost,
3302 Exts, Truncs, TLI, true);
3303 }
3304
3305 /// \see promoteOperandForOther.
3306 static Value *zeroExtendOperandForOther(
3307 Instruction *Ext, TypePromotionTransaction &TPT,
3308 InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
3309 SmallVectorImpl<Instruction *> *Exts,
3310 SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI) {
3311 return promoteOperandForOther(Ext, TPT, PromotedInsts, CreatedInstsCost,
3312 Exts, Truncs, TLI, false);
3313 }
3314
3315public:
3316 /// Type for the utility function that promotes the operand of Ext.
3317 using Action = Value *(*)(Instruction *Ext, TypePromotionTransaction &TPT,
3318 InstrToOrigTy &PromotedInsts,
3319 unsigned &CreatedInstsCost,
3320 SmallVectorImpl<Instruction *> *Exts,
3321 SmallVectorImpl<Instruction *> *Truncs,
3322 const TargetLowering &TLI);
3323
3324 /// \brief Given a sign/zero extend instruction \p Ext, return the approriate
3325 /// action to promote the operand of \p Ext instead of using Ext.
3326 /// \return NULL if no promotable action is possible with the current
3327 /// sign extension.
3328 /// \p InsertedInsts keeps track of all the instructions inserted by the
3329 /// other CodeGenPrepare optimizations. This information is important
3330 /// because we do not want to promote these instructions as CodeGenPrepare
3331 /// will reinsert them later. Thus creating an infinite loop: create/remove.
3332 /// \p PromotedInsts maps the instructions to their type before promotion.
3333 static Action getAction(Instruction *Ext, const SetOfInstrs &InsertedInsts,
3334 const TargetLowering &TLI,
3335 const InstrToOrigTy &PromotedInsts);
3336};
3337
3338} // end anonymous namespace
3339
3340bool TypePromotionHelper::canGetThrough(const Instruction *Inst,
3341 Type *ConsideredExtType,
3342 const InstrToOrigTy &PromotedInsts,
3343 bool IsSExt) {
3344 // The promotion helper does not know how to deal with vector types yet.
3345 // To be able to fix that, we would need to fix the places where we
3346 // statically extend, e.g., constants and such.
3347 if (Inst->getType()->isVectorTy())
3348 return false;
3349
3350 // We can always get through zext.
3351 if (isa<ZExtInst>(Inst))
3352 return true;
3353
3354 // sext(sext) is ok too.
3355 if (IsSExt && isa<SExtInst>(Inst))
3356 return true;
3357
3358 // We can get through binary operator, if it is legal. In other words, the
3359 // binary operator must have a nuw or nsw flag.
3360 const BinaryOperator *BinOp = dyn_cast<BinaryOperator>(Inst);
3361 if (BinOp && isa<OverflowingBinaryOperator>(BinOp) &&
3362 ((!IsSExt && BinOp->hasNoUnsignedWrap()) ||
3363 (IsSExt && BinOp->hasNoSignedWrap())))
3364 return true;
3365
3366 // Check if we can do the following simplification.
3367 // ext(trunc(opnd)) --> ext(opnd)
3368 if (!isa<TruncInst>(Inst))
3369 return false;
3370
3371 Value *OpndVal = Inst->getOperand(0);
3372 // Check if we can use this operand in the extension.
3373 // If the type is larger than the result type of the extension, we cannot.
3374 if (!OpndVal->getType()->isIntegerTy() ||
3375 OpndVal->getType()->getIntegerBitWidth() >
3376 ConsideredExtType->getIntegerBitWidth())
3377 return false;
3378
3379 // If the operand of the truncate is not an instruction, we will not have
3380 // any information on the dropped bits.
3381 // (Actually we could for constant but it is not worth the extra logic).
3382 Instruction *Opnd = dyn_cast<Instruction>(OpndVal);
3383 if (!Opnd)
3384 return false;
3385
3386 // Check if the source of the type is narrow enough.
3387 // I.e., check that trunc just drops extended bits of the same kind of
3388 // the extension.
3389 // #1 get the type of the operand and check the kind of the extended bits.
3390 const Type *OpndType;
3391 InstrToOrigTy::const_iterator It = PromotedInsts.find(Opnd);
3392 if (It != PromotedInsts.end() && It->second.getInt() == IsSExt)
3393 OpndType = It->second.getPointer();
3394 else if ((IsSExt && isa<SExtInst>(Opnd)) || (!IsSExt && isa<ZExtInst>(Opnd)))
3395 OpndType = Opnd->getOperand(0)->getType();
3396 else
3397 return false;
3398
3399 // #2 check that the truncate just drops extended bits.
3400 return Inst->getType()->getIntegerBitWidth() >=
3401 OpndType->getIntegerBitWidth();
3402}
3403
3404TypePromotionHelper::Action TypePromotionHelper::getAction(
3405 Instruction *Ext, const SetOfInstrs &InsertedInsts,
3406 const TargetLowering &TLI, const InstrToOrigTy &PromotedInsts) {
3407 assert((isa<SExtInst>(Ext) || isa<ZExtInst>(Ext)) &&(static_cast <bool> ((isa<SExtInst>(Ext) || isa<
ZExtInst>(Ext)) && "Unexpected instruction type") ?
void (0) : __assert_fail ("(isa<SExtInst>(Ext) || isa<ZExtInst>(Ext)) && \"Unexpected instruction type\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 3408, __extension__ __PRETTY_FUNCTION__))
3408 "Unexpected instruction type")(static_cast <bool> ((isa<SExtInst>(Ext) || isa<
ZExtInst>(Ext)) && "Unexpected instruction type") ?
void (0) : __assert_fail ("(isa<SExtInst>(Ext) || isa<ZExtInst>(Ext)) && \"Unexpected instruction type\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 3408, __extension__ __PRETTY_FUNCTION__))
;
3409 Instruction *ExtOpnd = dyn_cast<Instruction>(Ext->getOperand(0));
3410 Type *ExtTy = Ext->getType();
3411 bool IsSExt = isa<SExtInst>(Ext);
3412 // If the operand of the extension is not an instruction, we cannot
3413 // get through.
3414 // If it, check we can get through.
3415 if (!ExtOpnd || !canGetThrough(ExtOpnd, ExtTy, PromotedInsts, IsSExt))
3416 return nullptr;
3417
3418 // Do not promote if the operand has been added by codegenprepare.
3419 // Otherwise, it means we are undoing an optimization that is likely to be
3420 // redone, thus causing potential infinite loop.
3421 if (isa<TruncInst>(ExtOpnd) && InsertedInsts.count(ExtOpnd))
3422 return nullptr;
3423
3424 // SExt or Trunc instructions.
3425 // Return the related handler.
3426 if (isa<SExtInst>(ExtOpnd) || isa<TruncInst>(ExtOpnd) ||
3427 isa<ZExtInst>(ExtOpnd))
3428 return promoteOperandForTruncAndAnyExt;
3429
3430 // Regular instruction.
3431 // Abort early if we will have to insert non-free instructions.
3432 if (!ExtOpnd->hasOneUse() && !TLI.isTruncateFree(ExtTy, ExtOpnd->getType()))
3433 return nullptr;
3434 return IsSExt ? signExtendOperandForOther : zeroExtendOperandForOther;
3435}
3436
3437Value *TypePromotionHelper::promoteOperandForTruncAndAnyExt(
3438 Instruction *SExt, TypePromotionTransaction &TPT,
3439 InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
3440 SmallVectorImpl<Instruction *> *Exts,
3441 SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI) {
3442 // By construction, the operand of SExt is an instruction. Otherwise we cannot
3443 // get through it and this method should not be called.
3444 Instruction *SExtOpnd = cast<Instruction>(SExt->getOperand(0));
3445 Value *ExtVal = SExt;
3446 bool HasMergedNonFreeExt = false;
3447 if (isa<ZExtInst>(SExtOpnd)) {
3448 // Replace s|zext(zext(opnd))
3449 // => zext(opnd).
3450 HasMergedNonFreeExt = !TLI.isExtFree(SExtOpnd);
3451 Value *ZExt =
3452 TPT.createZExt(SExt, SExtOpnd->getOperand(0), SExt->getType());
3453 TPT.replaceAllUsesWith(SExt, ZExt);
3454 TPT.eraseInstruction(SExt);
3455 ExtVal = ZExt;
3456 } else {
3457 // Replace z|sext(trunc(opnd)) or sext(sext(opnd))
3458 // => z|sext(opnd).
3459 TPT.setOperand(SExt, 0, SExtOpnd->getOperand(0));
3460 }
3461 CreatedInstsCost = 0;
3462
3463 // Remove dead code.
3464 if (SExtOpnd->use_empty())
3465 TPT.eraseInstruction(SExtOpnd);
3466
3467 // Check if the extension is still needed.
3468 Instruction *ExtInst = dyn_cast<Instruction>(ExtVal);
3469 if (!ExtInst || ExtInst->getType() != ExtInst->getOperand(0)->getType()) {
3470 if (ExtInst) {
3471 if (Exts)
3472 Exts->push_back(ExtInst);
3473 CreatedInstsCost = !TLI.isExtFree(ExtInst) && !HasMergedNonFreeExt;
3474 }
3475 return ExtVal;
3476 }
3477
3478 // At this point we have: ext ty opnd to ty.
3479 // Reassign the uses of ExtInst to the opnd and remove ExtInst.
3480 Value *NextVal = ExtInst->getOperand(0);
3481 TPT.eraseInstruction(ExtInst, NextVal);
3482 return NextVal;
3483}
3484
3485Value *TypePromotionHelper::promoteOperandForOther(
3486 Instruction *Ext, TypePromotionTransaction &TPT,
3487 InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
3488 SmallVectorImpl<Instruction *> *Exts,
3489 SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI,
3490 bool IsSExt) {
3491 // By construction, the operand of Ext is an instruction. Otherwise we cannot
3492 // get through it and this method should not be called.
3493 Instruction *ExtOpnd = cast<Instruction>(Ext->getOperand(0));
3494 CreatedInstsCost = 0;
3495 if (!ExtOpnd->hasOneUse()) {
3496 // ExtOpnd will be promoted.
3497 // All its uses, but Ext, will need to use a truncated value of the
3498 // promoted version.
3499 // Create the truncate now.
3500 Value *Trunc = TPT.createTrunc(Ext, ExtOpnd->getType());
3501 if (Instruction *ITrunc = dyn_cast<Instruction>(Trunc)) {
3502 // Insert it just after the definition.
3503 ITrunc->moveAfter(ExtOpnd);
3504 if (Truncs)
3505 Truncs->push_back(ITrunc);
3506 }
3507
3508 TPT.replaceAllUsesWith(ExtOpnd, Trunc);
3509 // Restore the operand of Ext (which has been replaced by the previous call
3510 // to replaceAllUsesWith) to avoid creating a cycle trunc <-> sext.
3511 TPT.setOperand(Ext, 0, ExtOpnd);
3512 }
3513
3514 // Get through the Instruction:
3515 // 1. Update its type.
3516 // 2. Replace the uses of Ext by Inst.
3517 // 3. Extend each operand that needs to be extended.
3518
3519 // Remember the original type of the instruction before promotion.
3520 // This is useful to know that the high bits are sign extended bits.
3521 PromotedInsts.insert(std::pair<Instruction *, TypeIsSExt>(
3522 ExtOpnd, TypeIsSExt(ExtOpnd->getType(), IsSExt)));
3523 // Step #1.
3524 TPT.mutateType(ExtOpnd, Ext->getType());
3525 // Step #2.
3526 TPT.replaceAllUsesWith(Ext, ExtOpnd);
3527 // Step #3.
3528 Instruction *ExtForOpnd = Ext;
3529
3530 DEBUG(dbgs() << "Propagate Ext to operands\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Propagate Ext to operands\n"
; } } while (false)
;
3531 for (int OpIdx = 0, EndOpIdx = ExtOpnd->getNumOperands(); OpIdx != EndOpIdx;
3532 ++OpIdx) {
3533 DEBUG(dbgs() << "Operand:\n" << *(ExtOpnd->getOperand(OpIdx)) << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Operand:\n" << *
(ExtOpnd->getOperand(OpIdx)) << '\n'; } } while (false
)
;
3534 if (ExtOpnd->getOperand(OpIdx)->getType() == Ext->getType() ||
3535 !shouldExtOperand(ExtOpnd, OpIdx)) {
3536 DEBUG(dbgs() << "No need to propagate\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "No need to propagate\n"
; } } while (false)
;
3537 continue;
3538 }
3539 // Check if we can statically extend the operand.
3540 Value *Opnd = ExtOpnd->getOperand(OpIdx);
3541 if (const ConstantInt *Cst = dyn_cast<ConstantInt>(Opnd)) {
3542 DEBUG(dbgs() << "Statically extend\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Statically extend\n"; }
} while (false)
;
3543 unsigned BitWidth = Ext->getType()->getIntegerBitWidth();
3544 APInt CstVal = IsSExt ? Cst->getValue().sext(BitWidth)
3545 : Cst->getValue().zext(BitWidth);
3546 TPT.setOperand(ExtOpnd, OpIdx, ConstantInt::get(Ext->getType(), CstVal));
3547 continue;
3548 }
3549 // UndefValue are typed, so we have to statically sign extend them.
3550 if (isa<UndefValue>(Opnd)) {
3551 DEBUG(dbgs() << "Statically extend\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Statically extend\n"; }
} while (false)
;
3552 TPT.setOperand(ExtOpnd, OpIdx, UndefValue::get(Ext->getType()));
3553 continue;
3554 }
3555
3556 // Otherwise we have to explicity sign extend the operand.
3557 // Check if Ext was reused to extend an operand.
3558 if (!ExtForOpnd) {
3559 // If yes, create a new one.
3560 DEBUG(dbgs() << "More operands to ext\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "More operands to ext\n"
; } } while (false)
;
3561 Value *ValForExtOpnd = IsSExt ? TPT.createSExt(Ext, Opnd, Ext->getType())
3562 : TPT.createZExt(Ext, Opnd, Ext->getType());
3563 if (!isa<Instruction>(ValForExtOpnd)) {
3564 TPT.setOperand(ExtOpnd, OpIdx, ValForExtOpnd);
3565 continue;
3566 }
3567 ExtForOpnd = cast<Instruction>(ValForExtOpnd);
3568 }
3569 if (Exts)
3570 Exts->push_back(ExtForOpnd);
3571 TPT.setOperand(ExtForOpnd, 0, Opnd);
3572
3573 // Move the sign extension before the insertion point.
3574 TPT.moveBefore(ExtForOpnd, ExtOpnd);
3575 TPT.setOperand(ExtOpnd, OpIdx, ExtForOpnd);
3576 CreatedInstsCost += !TLI.isExtFree(ExtForOpnd);
3577 // If more sext are required, new instructions will have to be created.
3578 ExtForOpnd = nullptr;
3579 }
3580 if (ExtForOpnd == Ext) {
3581 DEBUG(dbgs() << "Extension is useless now\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Extension is useless now\n"
; } } while (false)
;
3582 TPT.eraseInstruction(Ext);
3583 }
3584 return ExtOpnd;
3585}
3586
3587/// Check whether or not promoting an instruction to a wider type is profitable.
3588/// \p NewCost gives the cost of extension instructions created by the
3589/// promotion.
3590/// \p OldCost gives the cost of extension instructions before the promotion
3591/// plus the number of instructions that have been
3592/// matched in the addressing mode the promotion.
3593/// \p PromotedOperand is the value that has been promoted.
3594/// \return True if the promotion is profitable, false otherwise.
3595bool AddressingModeMatcher::isPromotionProfitable(
3596 unsigned NewCost, unsigned OldCost, Value *PromotedOperand) const {
3597 DEBUG(dbgs() << "OldCost: " << OldCost << "\tNewCost: " << NewCost << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "OldCost: " << OldCost
<< "\tNewCost: " << NewCost << '\n'; } } while
(false)
;
3598 // The cost of the new extensions is greater than the cost of the
3599 // old extension plus what we folded.
3600 // This is not profitable.
3601 if (NewCost > OldCost)
3602 return false;
3603 if (NewCost < OldCost)
3604 return true;
3605 // The promotion is neutral but it may help folding the sign extension in
3606 // loads for instance.
3607 // Check that we did not create an illegal instruction.
3608 return isPromotedInstructionLegal(TLI, DL, PromotedOperand);
3609}
3610
3611/// Given an instruction or constant expr, see if we can fold the operation
3612/// into the addressing mode. If so, update the addressing mode and return
3613/// true, otherwise return false without modifying AddrMode.
3614/// If \p MovedAway is not NULL, it contains the information of whether or
3615/// not AddrInst has to be folded into the addressing mode on success.
3616/// If \p MovedAway == true, \p AddrInst will not be part of the addressing
3617/// because it has been moved away.
3618/// Thus AddrInst must not be added in the matched instructions.
3619/// This state can happen when AddrInst is a sext, since it may be moved away.
3620/// Therefore, AddrInst may not be valid when MovedAway is true and it must
3621/// not be referenced anymore.
3622bool AddressingModeMatcher::matchOperationAddr(User *AddrInst, unsigned Opcode,
3623 unsigned Depth,
3624 bool *MovedAway) {
3625 // Avoid exponential behavior on extremely deep expression trees.
3626 if (Depth >= 5) return false;
3627
3628 // By default, all matched instructions stay in place.
3629 if (MovedAway)
3630 *MovedAway = false;
3631
3632 switch (Opcode) {
3633 case Instruction::PtrToInt:
3634 // PtrToInt is always a noop, as we know that the int type is pointer sized.
3635 return matchAddr(AddrInst->getOperand(0), Depth);
3636 case Instruction::IntToPtr: {
3637 auto AS = AddrInst->getType()->getPointerAddressSpace();
3638 auto PtrTy = MVT::getIntegerVT(DL.getPointerSizeInBits(AS));
3639 // This inttoptr is a no-op if the integer type is pointer sized.
3640 if (TLI.getValueType(DL, AddrInst->getOperand(0)->getType()) == PtrTy)
3641 return matchAddr(AddrInst->getOperand(0), Depth);
3642 return false;
3643 }
3644 case Instruction::BitCast:
3645 // BitCast is always a noop, and we can handle it as long as it is
3646 // int->int or pointer->pointer (we don't want int<->fp or something).
3647 if ((AddrInst->getOperand(0)->getType()->isPointerTy() ||
3648 AddrInst->getOperand(0)->getType()->isIntegerTy()) &&
3649 // Don't touch identity bitcasts. These were probably put here by LSR,
3650 // and we don't want to mess around with them. Assume it knows what it
3651 // is doing.
3652 AddrInst->getOperand(0)->getType() != AddrInst->getType())
3653 return matchAddr(AddrInst->getOperand(0), Depth);
3654 return false;
3655 case Instruction::AddrSpaceCast: {
3656 unsigned SrcAS
3657 = AddrInst->getOperand(0)->getType()->getPointerAddressSpace();
3658 unsigned DestAS = AddrInst->getType()->getPointerAddressSpace();
3659 if (TLI.isNoopAddrSpaceCast(SrcAS, DestAS))
3660 return matchAddr(AddrInst->getOperand(0), Depth);
3661 return false;
3662 }
3663 case Instruction::Add: {
3664 // Check to see if we can merge in the RHS then the LHS. If so, we win.
3665 ExtAddrMode BackupAddrMode = AddrMode;
3666 unsigned OldSize = AddrModeInsts.size();
3667 // Start a transaction at this point.
3668 // The LHS may match but not the RHS.
3669 // Therefore, we need a higher level restoration point to undo partially
3670 // matched operation.
3671 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
3672 TPT.getRestorationPoint();
3673
3674 if (matchAddr(AddrInst->getOperand(1), Depth+1) &&
3675 matchAddr(AddrInst->getOperand(0), Depth+1))
3676 return true;
3677
3678 // Restore the old addr mode info.
3679 AddrMode = BackupAddrMode;
3680 AddrModeInsts.resize(OldSize);
3681 TPT.rollback(LastKnownGood);
3682
3683 // Otherwise this was over-aggressive. Try merging in the LHS then the RHS.
3684 if (matchAddr(AddrInst->getOperand(0), Depth+1) &&
3685 matchAddr(AddrInst->getOperand(1), Depth+1))
3686 return true;
3687
3688 // Otherwise we definitely can't merge the ADD in.
3689 AddrMode = BackupAddrMode;
3690 AddrModeInsts.resize(OldSize);
3691 TPT.rollback(LastKnownGood);
3692 break;
3693 }
3694 //case Instruction::Or:
3695 // TODO: We can handle "Or Val, Imm" iff this OR is equivalent to an ADD.
3696 //break;
3697 case Instruction::Mul:
3698 case Instruction::Shl: {
3699 // Can only handle X*C and X << C.
3700 ConstantInt *RHS = dyn_cast<ConstantInt>(AddrInst->getOperand(1));
3701 if (!RHS || RHS->getBitWidth() > 64)
3702 return false;
3703 int64_t Scale = RHS->getSExtValue();
3704 if (Opcode == Instruction::Shl)
3705 Scale = 1LL << Scale;
3706
3707 return matchScaledValue(AddrInst->getOperand(0), Scale, Depth);
3708 }
3709 case Instruction::GetElementPtr: {
3710 // Scan the GEP. We check it if it contains constant offsets and at most
3711 // one variable offset.
3712 int VariableOperand = -1;
3713 unsigned VariableScale = 0;
3714
3715 int64_t ConstantOffset = 0;
3716 gep_type_iterator GTI = gep_type_begin(AddrInst);
3717 for (unsigned i = 1, e = AddrInst->getNumOperands(); i != e; ++i, ++GTI) {
3718 if (StructType *STy = GTI.getStructTypeOrNull()) {
3719 const StructLayout *SL = DL.getStructLayout(STy);
3720 unsigned Idx =
3721 cast<ConstantInt>(AddrInst->getOperand(i))->getZExtValue();
3722 ConstantOffset += SL->getElementOffset(Idx);
3723 } else {
3724 uint64_t TypeSize = DL.getTypeAllocSize(GTI.getIndexedType());
3725 if (ConstantInt *CI = dyn_cast<ConstantInt>(AddrInst->getOperand(i))) {
3726 ConstantOffset += CI->getSExtValue() * TypeSize;
3727 } else if (TypeSize) { // Scales of zero don't do anything.
3728 // We only allow one variable index at the moment.
3729 if (VariableOperand != -1)
3730 return false;
3731
3732 // Remember the variable index.
3733 VariableOperand = i;
3734 VariableScale = TypeSize;
3735 }
3736 }
3737 }
3738
3739 // A common case is for the GEP to only do a constant offset. In this case,
3740 // just add it to the disp field and check validity.
3741 if (VariableOperand == -1) {
3742 AddrMode.BaseOffs += ConstantOffset;
3743 if (ConstantOffset == 0 ||
3744 TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace)) {
3745 // Check to see if we can fold the base pointer in too.
3746 if (matchAddr(AddrInst->getOperand(0), Depth+1))
3747 return true;
3748 }
3749 AddrMode.BaseOffs -= ConstantOffset;
3750 return false;
3751 }
3752
3753 // Save the valid addressing mode in case we can't match.
3754 ExtAddrMode BackupAddrMode = AddrMode;
3755 unsigned OldSize = AddrModeInsts.size();
3756
3757 // See if the scale and offset amount is valid for this target.
3758 AddrMode.BaseOffs += ConstantOffset;
3759
3760 // Match the base operand of the GEP.
3761 if (!matchAddr(AddrInst->getOperand(0), Depth+1)) {
3762 // If it couldn't be matched, just stuff the value in a register.
3763 if (AddrMode.HasBaseReg) {
3764 AddrMode = BackupAddrMode;
3765 AddrModeInsts.resize(OldSize);
3766 return false;
3767 }
3768 AddrMode.HasBaseReg = true;
3769 AddrMode.BaseReg = AddrInst->getOperand(0);
3770 }
3771
3772 // Match the remaining variable portion of the GEP.
3773 if (!matchScaledValue(AddrInst->getOperand(VariableOperand), VariableScale,
3774 Depth)) {
3775 // If it couldn't be matched, try stuffing the base into a register
3776 // instead of matching it, and retrying the match of the scale.
3777 AddrMode = BackupAddrMode;
3778 AddrModeInsts.resize(OldSize);
3779 if (AddrMode.HasBaseReg)
3780 return false;
3781 AddrMode.HasBaseReg = true;
3782 AddrMode.BaseReg = AddrInst->getOperand(0);
3783 AddrMode.BaseOffs += ConstantOffset;
3784 if (!matchScaledValue(AddrInst->getOperand(VariableOperand),
3785 VariableScale, Depth)) {
3786 // If even that didn't work, bail.
3787 AddrMode = BackupAddrMode;
3788 AddrModeInsts.resize(OldSize);
3789 return false;
3790 }
3791 }
3792
3793 return true;
3794 }
3795 case Instruction::SExt:
3796 case Instruction::ZExt: {
3797 Instruction *Ext = dyn_cast<Instruction>(AddrInst);
3798 if (!Ext)
3799 return false;
3800
3801 // Try to move this ext out of the way of the addressing mode.
3802 // Ask for a method for doing so.
3803 TypePromotionHelper::Action TPH =
3804 TypePromotionHelper::getAction(Ext, InsertedInsts, TLI, PromotedInsts);
3805 if (!TPH)
3806 return false;
3807
3808 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
3809 TPT.getRestorationPoint();
3810 unsigned CreatedInstsCost = 0;
3811 unsigned ExtCost = !TLI.isExtFree(Ext);
3812 Value *PromotedOperand =
3813 TPH(Ext, TPT, PromotedInsts, CreatedInstsCost, nullptr, nullptr, TLI);
3814 // SExt has been moved away.
3815 // Thus either it will be rematched later in the recursive calls or it is
3816 // gone. Anyway, we must not fold it into the addressing mode at this point.
3817 // E.g.,
3818 // op = add opnd, 1
3819 // idx = ext op
3820 // addr = gep base, idx
3821 // is now:
3822 // promotedOpnd = ext opnd <- no match here
3823 // op = promoted_add promotedOpnd, 1 <- match (later in recursive calls)
3824 // addr = gep base, op <- match
3825 if (MovedAway)
3826 *MovedAway = true;
3827
3828 assert(PromotedOperand &&(static_cast <bool> (PromotedOperand && "TypePromotionHelper should have filtered out those cases"
) ? void (0) : __assert_fail ("PromotedOperand && \"TypePromotionHelper should have filtered out those cases\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 3829, __extension__ __PRETTY_FUNCTION__))
3829 "TypePromotionHelper should have filtered out those cases")(static_cast <bool> (PromotedOperand && "TypePromotionHelper should have filtered out those cases"
) ? void (0) : __assert_fail ("PromotedOperand && \"TypePromotionHelper should have filtered out those cases\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 3829, __extension__ __PRETTY_FUNCTION__))
;
3830
3831 ExtAddrMode BackupAddrMode = AddrMode;
3832 unsigned OldSize = AddrModeInsts.size();
3833
3834 if (!matchAddr(PromotedOperand, Depth) ||
3835 // The total of the new cost is equal to the cost of the created
3836 // instructions.
3837 // The total of the old cost is equal to the cost of the extension plus
3838 // what we have saved in the addressing mode.
3839 !isPromotionProfitable(CreatedInstsCost,
3840 ExtCost + (AddrModeInsts.size() - OldSize),
3841 PromotedOperand)) {
3842 AddrMode = BackupAddrMode;
3843 AddrModeInsts.resize(OldSize);
3844 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)
;
3845 TPT.rollback(LastKnownGood);
3846 return false;
3847 }
3848 return true;
3849 }
3850 }
3851 return false;
3852}
3853
3854/// If we can, try to add the value of 'Addr' into the current addressing mode.
3855/// If Addr can't be added to AddrMode this returns false and leaves AddrMode
3856/// unmodified. This assumes that Addr is either a pointer type or intptr_t
3857/// for the target.
3858///
3859bool AddressingModeMatcher::matchAddr(Value *Addr, unsigned Depth) {
3860 // Start a transaction at this point that we will rollback if the matching
3861 // fails.
3862 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
3863 TPT.getRestorationPoint();
3864 if (ConstantInt *CI = dyn_cast<ConstantInt>(Addr)) {
3865 // Fold in immediates if legal for the target.
3866 AddrMode.BaseOffs += CI->getSExtValue();
3867 if (TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace))
3868 return true;
3869 AddrMode.BaseOffs -= CI->getSExtValue();
3870 } else if (GlobalValue *GV = dyn_cast<GlobalValue>(Addr)) {
3871 // If this is a global variable, try to fold it into the addressing mode.
3872 if (!AddrMode.BaseGV) {
3873 AddrMode.BaseGV = GV;
3874 if (TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace))
3875 return true;
3876 AddrMode.BaseGV = nullptr;
3877 }
3878 } else if (Instruction *I = dyn_cast<Instruction>(Addr)) {
3879 ExtAddrMode BackupAddrMode = AddrMode;
3880 unsigned OldSize = AddrModeInsts.size();
3881
3882 // Check to see if it is possible to fold this operation.
3883 bool MovedAway = false;
3884 if (matchOperationAddr(I, I->getOpcode(), Depth, &MovedAway)) {
3885 // This instruction may have been moved away. If so, there is nothing
3886 // to check here.
3887 if (MovedAway)
3888 return true;
3889 // Okay, it's possible to fold this. Check to see if it is actually
3890 // *profitable* to do so. We use a simple cost model to avoid increasing
3891 // register pressure too much.
3892 if (I->hasOneUse() ||
3893 isProfitableToFoldIntoAddressingMode(I, BackupAddrMode, AddrMode)) {
3894 AddrModeInsts.push_back(I);
3895 return true;
3896 }
3897
3898 // It isn't profitable to do this, roll back.
3899 //cerr << "NOT FOLDING: " << *I;
3900 AddrMode = BackupAddrMode;
3901 AddrModeInsts.resize(OldSize);
3902 TPT.rollback(LastKnownGood);
3903 }
3904 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Addr)) {
3905 if (matchOperationAddr(CE, CE->getOpcode(), Depth))
3906 return true;
3907 TPT.rollback(LastKnownGood);
3908 } else if (isa<ConstantPointerNull>(Addr)) {
3909 // Null pointer gets folded without affecting the addressing mode.
3910 return true;
3911 }
3912
3913 // Worse case, the target should support [reg] addressing modes. :)
3914 if (!AddrMode.HasBaseReg) {
3915 AddrMode.HasBaseReg = true;
3916 AddrMode.BaseReg = Addr;
3917 // Still check for legality in case the target supports [imm] but not [i+r].
3918 if (TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace))
3919 return true;
3920 AddrMode.HasBaseReg = false;
3921 AddrMode.BaseReg = nullptr;
3922 }
3923
3924 // If the base register is already taken, see if we can do [r+r].
3925 if (AddrMode.Scale == 0) {
3926 AddrMode.Scale = 1;
3927 AddrMode.ScaledReg = Addr;
3928 if (TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace))
3929 return true;
3930 AddrMode.Scale = 0;
3931 AddrMode.ScaledReg = nullptr;
3932 }
3933 // Couldn't match.
3934 TPT.rollback(LastKnownGood);
3935 return false;
3936}
3937
3938/// Check to see if all uses of OpVal by the specified inline asm call are due
3939/// to memory operands. If so, return true, otherwise return false.
3940static bool IsOperandAMemoryOperand(CallInst *CI, InlineAsm *IA, Value *OpVal,
3941 const TargetLowering &TLI,
3942 const TargetRegisterInfo &TRI) {
3943 const Function *F = CI->getFunction();
3944 TargetLowering::AsmOperandInfoVector TargetConstraints =
3945 TLI.ParseConstraints(F->getParent()->getDataLayout(), &TRI,
3946 ImmutableCallSite(CI));
3947
3948 for (unsigned i = 0, e = TargetConstraints.size(); i != e; ++i) {
3949 TargetLowering::AsmOperandInfo &OpInfo = TargetConstraints[i];
3950
3951 // Compute the constraint code and ConstraintType to use.
3952 TLI.ComputeConstraintToUse(OpInfo, SDValue());
3953
3954 // If this asm operand is our Value*, and if it isn't an indirect memory
3955 // operand, we can't fold it!
3956 if (OpInfo.CallOperandVal == OpVal &&
3957 (OpInfo.ConstraintType != TargetLowering::C_Memory ||
3958 !OpInfo.isIndirect))
3959 return false;
3960 }
3961
3962 return true;
3963}
3964
3965// Max number of memory uses to look at before aborting the search to conserve
3966// compile time.
3967static constexpr int MaxMemoryUsesToScan = 20;
3968
3969/// Recursively walk all the uses of I until we find a memory use.
3970/// If we find an obviously non-foldable instruction, return true.
3971/// Add the ultimately found memory instructions to MemoryUses.
3972static bool FindAllMemoryUses(
3973 Instruction *I,
3974 SmallVectorImpl<std::pair<Instruction *, unsigned>> &MemoryUses,
3975 SmallPtrSetImpl<Instruction *> &ConsideredInsts, const TargetLowering &TLI,
3976 const TargetRegisterInfo &TRI, int SeenInsts = 0) {
3977 // If we already considered this instruction, we're done.
3978 if (!ConsideredInsts.insert(I).second)
3979 return false;
3980
3981 // If this is an obviously unfoldable instruction, bail out.
3982 if (!MightBeFoldableInst(I))
3983 return true;
3984
3985 const bool OptSize = I->getFunction()->optForSize();
3986
3987 // Loop over all the uses, recursively processing them.
3988 for (Use &U : I->uses()) {
3989 // Conservatively return true if we're seeing a large number or a deep chain
3990 // of users. This avoids excessive compilation times in pathological cases.
3991 if (SeenInsts++ >= MaxMemoryUsesToScan)
3992 return true;
3993
3994 Instruction *UserI = cast<Instruction>(U.getUser());
3995 if (LoadInst *LI = dyn_cast<LoadInst>(UserI)) {
3996 MemoryUses.push_back(std::make_pair(LI, U.getOperandNo()));
3997 continue;
3998 }
3999
4000 if (StoreInst *SI = dyn_cast<StoreInst>(UserI)) {
4001 unsigned opNo = U.getOperandNo();
4002 if (opNo != StoreInst::getPointerOperandIndex())
4003 return true; // Storing addr, not into addr.
4004 MemoryUses.push_back(std::make_pair(SI, opNo));
4005 continue;
4006 }
4007
4008 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(UserI)) {
4009 unsigned opNo = U.getOperandNo();
4010 if (opNo != AtomicRMWInst::getPointerOperandIndex())
4011 return true; // Storing addr, not into addr.
4012 MemoryUses.push_back(std::make_pair(RMW, opNo));
4013 continue;
4014 }
4015
4016 if (AtomicCmpXchgInst *CmpX = dyn_cast<AtomicCmpXchgInst>(UserI)) {
4017 unsigned opNo = U.getOperandNo();
4018 if (opNo != AtomicCmpXchgInst::getPointerOperandIndex())
4019 return true; // Storing addr, not into addr.
4020 MemoryUses.push_back(std::make_pair(CmpX, opNo));
4021 continue;
4022 }
4023
4024 if (CallInst *CI = dyn_cast<CallInst>(UserI)) {
4025 // If this is a cold call, we can sink the addressing calculation into
4026 // the cold path. See optimizeCallInst
4027 if (!OptSize && CI->hasFnAttr(Attribute::Cold))
4028 continue;
4029
4030 InlineAsm *IA = dyn_cast<InlineAsm>(CI->getCalledValue());
4031 if (!IA) return true;
4032
4033 // If this is a memory operand, we're cool, otherwise bail out.
4034 if (!IsOperandAMemoryOperand(CI, IA, I, TLI, TRI))
4035 return true;
4036 continue;
4037 }
4038
4039 if (FindAllMemoryUses(UserI, MemoryUses, ConsideredInsts, TLI, TRI,
4040 SeenInsts))
4041 return true;
4042 }
4043
4044 return false;
4045}
4046
4047/// Return true if Val is already known to be live at the use site that we're
4048/// folding it into. If so, there is no cost to include it in the addressing
4049/// mode. KnownLive1 and KnownLive2 are two values that we know are live at the
4050/// instruction already.
4051bool AddressingModeMatcher::valueAlreadyLiveAtInst(Value *Val,Value *KnownLive1,
4052 Value *KnownLive2) {
4053 // If Val is either of the known-live values, we know it is live!
4054 if (Val == nullptr || Val == KnownLive1 || Val == KnownLive2)
4055 return true;
4056
4057 // All values other than instructions and arguments (e.g. constants) are live.
4058 if (!isa<Instruction>(Val) && !isa<Argument>(Val)) return true;
4059
4060 // If Val is a constant sized alloca in the entry block, it is live, this is
4061 // true because it is just a reference to the stack/frame pointer, which is
4062 // live for the whole function.
4063 if (AllocaInst *AI = dyn_cast<AllocaInst>(Val))
4064 if (AI->isStaticAlloca())
4065 return true;
4066
4067 // Check to see if this value is already used in the memory instruction's
4068 // block. If so, it's already live into the block at the very least, so we
4069 // can reasonably fold it.
4070 return Val->isUsedInBasicBlock(MemoryInst->getParent());
4071}
4072
4073/// It is possible for the addressing mode of the machine to fold the specified
4074/// instruction into a load or store that ultimately uses it.
4075/// However, the specified instruction has multiple uses.
4076/// Given this, it may actually increase register pressure to fold it
4077/// into the load. For example, consider this code:
4078///
4079/// X = ...
4080/// Y = X+1
4081/// use(Y) -> nonload/store
4082/// Z = Y+1
4083/// load Z
4084///
4085/// In this case, Y has multiple uses, and can be folded into the load of Z
4086/// (yielding load [X+2]). However, doing this will cause both "X" and "X+1" to
4087/// be live at the use(Y) line. If we don't fold Y into load Z, we use one
4088/// fewer register. Since Y can't be folded into "use(Y)" we don't increase the
4089/// number of computations either.
4090///
4091/// Note that this (like most of CodeGenPrepare) is just a rough heuristic. If
4092/// X was live across 'load Z' for other reasons, we actually *would* want to
4093/// fold the addressing mode in the Z case. This would make Y die earlier.
4094bool AddressingModeMatcher::
4095isProfitableToFoldIntoAddressingMode(Instruction *I, ExtAddrMode &AMBefore,
4096 ExtAddrMode &AMAfter) {
4097 if (IgnoreProfitability) return true;
4098
4099 // AMBefore is the addressing mode before this instruction was folded into it,
4100 // and AMAfter is the addressing mode after the instruction was folded. Get
4101 // the set of registers referenced by AMAfter and subtract out those
4102 // referenced by AMBefore: this is the set of values which folding in this
4103 // address extends the lifetime of.
4104 //
4105 // Note that there are only two potential values being referenced here,
4106 // BaseReg and ScaleReg (global addresses are always available, as are any
4107 // folded immediates).
4108 Value *BaseReg = AMAfter.BaseReg, *ScaledReg = AMAfter.ScaledReg;
4109
4110 // If the BaseReg or ScaledReg was referenced by the previous addrmode, their
4111 // lifetime wasn't extended by adding this instruction.
4112 if (valueAlreadyLiveAtInst(BaseReg, AMBefore.BaseReg, AMBefore.ScaledReg))
4113 BaseReg = nullptr;
4114 if (valueAlreadyLiveAtInst(ScaledReg, AMBefore.BaseReg, AMBefore.ScaledReg))
4115 ScaledReg = nullptr;
4116
4117 // If folding this instruction (and it's subexprs) didn't extend any live
4118 // ranges, we're ok with it.
4119 if (!BaseReg && !ScaledReg)
4120 return true;
4121
4122 // If all uses of this instruction can have the address mode sunk into them,
4123 // we can remove the addressing mode and effectively trade one live register
4124 // for another (at worst.) In this context, folding an addressing mode into
4125 // the use is just a particularly nice way of sinking it.
4126 SmallVector<std::pair<Instruction*,unsigned>, 16> MemoryUses;
4127 SmallPtrSet<Instruction*, 16> ConsideredInsts;
4128 if (FindAllMemoryUses(I, MemoryUses, ConsideredInsts, TLI, TRI))
4129 return false; // Has a non-memory, non-foldable use!
4130
4131 // Now that we know that all uses of this instruction are part of a chain of
4132 // computation involving only operations that could theoretically be folded
4133 // into a memory use, loop over each of these memory operation uses and see
4134 // if they could *actually* fold the instruction. The assumption is that
4135 // addressing modes are cheap and that duplicating the computation involved
4136 // many times is worthwhile, even on a fastpath. For sinking candidates
4137 // (i.e. cold call sites), this serves as a way to prevent excessive code
4138 // growth since most architectures have some reasonable small and fast way to
4139 // compute an effective address. (i.e LEA on x86)
4140 SmallVector<Instruction*, 32> MatchedAddrModeInsts;
4141 for (unsigned i = 0, e = MemoryUses.size(); i != e; ++i) {
4142 Instruction *User = MemoryUses[i].first;
4143 unsigned OpNo = MemoryUses[i].second;
4144
4145 // Get the access type of this use. If the use isn't a pointer, we don't
4146 // know what it accesses.
4147 Value *Address = User->getOperand(OpNo);
4148 PointerType *AddrTy = dyn_cast<PointerType>(Address->getType());
4149 if (!AddrTy)
4150 return false;
4151 Type *AddressAccessTy = AddrTy->getElementType();
4152 unsigned AS = AddrTy->getAddressSpace();
4153
4154 // Do a match against the root of this address, ignoring profitability. This
4155 // will tell us if the addressing mode for the memory operation will
4156 // *actually* cover the shared instruction.
4157 ExtAddrMode Result;
4158 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
4159 TPT.getRestorationPoint();
4160 AddressingModeMatcher Matcher(MatchedAddrModeInsts, TLI, TRI,
4161 AddressAccessTy, AS,
4162 MemoryInst, Result, InsertedInsts,
4163 PromotedInsts, TPT);
4164 Matcher.IgnoreProfitability = true;
4165 bool Success = Matcher.matchAddr(Address, 0);
4166 (void)Success; assert(Success && "Couldn't select *anything*?")(static_cast <bool> (Success && "Couldn't select *anything*?"
) ? void (0) : __assert_fail ("Success && \"Couldn't select *anything*?\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 4166, __extension__ __PRETTY_FUNCTION__))
;
4167
4168 // The match was to check the profitability, the changes made are not
4169 // part of the original matcher. Therefore, they should be dropped
4170 // otherwise the original matcher will not present the right state.
4171 TPT.rollback(LastKnownGood);
4172
4173 // If the match didn't cover I, then it won't be shared by it.
4174 if (!is_contained(MatchedAddrModeInsts, I))
4175 return false;
4176
4177 MatchedAddrModeInsts.clear();
4178 }
4179
4180 return true;
4181}
4182
4183/// Return true if the specified values are defined in a
4184/// different basic block than BB.
4185static bool IsNonLocalValue(Value *V, BasicBlock *BB) {
4186 if (Instruction *I = dyn_cast<Instruction>(V))
4187 return I->getParent() != BB;
4188 return false;
4189}
4190
4191/// Sink addressing mode computation immediate before MemoryInst if doing so
4192/// can be done without increasing register pressure. The need for the
4193/// register pressure constraint means this can end up being an all or nothing
4194/// decision for all uses of the same addressing computation.
4195///
4196/// Load and Store Instructions often have addressing modes that can do
4197/// significant amounts of computation. As such, instruction selection will try
4198/// to get the load or store to do as much computation as possible for the
4199/// program. The problem is that isel can only see within a single block. As
4200/// such, we sink as much legal addressing mode work into the block as possible.
4201///
4202/// This method is used to optimize both load/store and inline asms with memory
4203/// operands. It's also used to sink addressing computations feeding into cold
4204/// call sites into their (cold) basic block.
4205///
4206/// The motivation for handling sinking into cold blocks is that doing so can
4207/// both enable other address mode sinking (by satisfying the register pressure
4208/// constraint above), and reduce register pressure globally (by removing the
4209/// addressing mode computation from the fast path entirely.).
4210bool CodeGenPrepare::optimizeMemoryInst(Instruction *MemoryInst, Value *Addr,
4211 Type *AccessTy, unsigned AddrSpace) {
4212 Value *Repl = Addr;
4213
4214 // Try to collapse single-value PHI nodes. This is necessary to undo
4215 // unprofitable PRE transformations.
4216 SmallVector<Value*, 8> worklist;
4217 SmallPtrSet<Value*, 16> Visited;
4218 worklist.push_back(Addr);
4219
4220 // Use a worklist to iteratively look through PHI and select nodes, and
4221 // ensure that the addressing mode obtained from the non-PHI/select roots of
4222 // the graph are compatible.
4223 bool PhiOrSelectSeen = false;
4224 SmallVector<Instruction*, 16> AddrModeInsts;
4225 const SimplifyQuery SQ(*DL, TLInfo);
4226 AddressingModeCombiner AddrModes(SQ, { Addr, MemoryInst->getParent() });
4227 TypePromotionTransaction TPT(RemovedInsts);
4228 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
4229 TPT.getRestorationPoint();
4230 while (!worklist.empty()) {
4231 Value *V = worklist.back();
4232 worklist.pop_back();
4233
4234 // We allow traversing cyclic Phi nodes.
4235 // In case of success after this loop we ensure that traversing through
4236 // Phi nodes ends up with all cases to compute address of the form
4237 // BaseGV + Base + Scale * Index + Offset
4238 // where Scale and Offset are constans and BaseGV, Base and Index
4239 // are exactly the same Values in all cases.
4240 // It means that BaseGV, Scale and Offset dominate our memory instruction
4241 // and have the same value as they had in address computation represented
4242 // as Phi. So we can safely sink address computation to memory instruction.
4243 if (!Visited.insert(V).second)
4244 continue;
4245
4246 // For a PHI node, push all of its incoming values.
4247 if (PHINode *P = dyn_cast<PHINode>(V)) {
4248 for (Value *IncValue : P->incoming_values())
4249 worklist.push_back(IncValue);
4250 PhiOrSelectSeen = true;
4251 continue;
4252 }
4253 // Similar for select.
4254 if (SelectInst *SI = dyn_cast<SelectInst>(V)) {
4255 worklist.push_back(SI->getFalseValue());
4256 worklist.push_back(SI->getTrueValue());
4257 PhiOrSelectSeen = true;
4258 continue;
4259 }
4260
4261 // For non-PHIs, determine the addressing mode being computed. Note that
4262 // the result may differ depending on what other uses our candidate
4263 // addressing instructions might have.
4264 AddrModeInsts.clear();
4265 ExtAddrMode NewAddrMode = AddressingModeMatcher::Match(
4266 V, AccessTy, AddrSpace, MemoryInst, AddrModeInsts, *TLI, *TRI,
4267 InsertedInsts, PromotedInsts, TPT);
4268 NewAddrMode.OriginalValue = V;
4269
4270 if (!AddrModes.addNewAddrMode(NewAddrMode))
4271 break;
4272 }
4273
4274 // Try to combine the AddrModes we've collected. If we couldn't collect any,
4275 // or we have multiple but either couldn't combine them or combining them
4276 // wouldn't do anything useful, bail out now.
4277 if (!AddrModes.combineAddrModes()) {
4278 TPT.rollback(LastKnownGood);
4279 return false;
4280 }
4281 TPT.commit();
4282
4283 // Get the combined AddrMode (or the only AddrMode, if we only had one).
4284 ExtAddrMode AddrMode = AddrModes.getAddrMode();
4285
4286 // If all the instructions matched are already in this BB, don't do anything.
4287 // If we saw a Phi node then it is not local definitely, and if we saw a select
4288 // then we want to push the address calculation past it even if it's already
4289 // in this BB.
4290 if (!PhiOrSelectSeen && none_of(AddrModeInsts, [&](Value *V) {
4291 return IsNonLocalValue(V, MemoryInst->getParent());
4292 })) {
4293 DEBUG(dbgs() << "CGP: Found local addrmode: " << AddrMode << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: Found local addrmode: "
<< AddrMode << "\n"; } } while (false)
;
4294 return false;
4295 }
4296
4297 // Insert this computation right after this user. Since our caller is
4298 // scanning from the top of the BB to the bottom, reuse of the expr are
4299 // guaranteed to happen later.
4300 IRBuilder<> Builder(MemoryInst);
4301
4302 // Now that we determined the addressing expression we want to use and know
4303 // that we have to sink it into this block. Check to see if we have already
4304 // done this for some other load/store instr in this block. If so, reuse
4305 // the computation. Before attempting reuse, check if the address is valid
4306 // as it may have been erased.
4307
4308 WeakTrackingVH SunkAddrVH = SunkAddrs[Addr];
4309
4310 Value * SunkAddr = SunkAddrVH.pointsToAliveValue() ? SunkAddrVH : nullptr;
4311 if (SunkAddr) {
4312 DEBUG(dbgs() << "CGP: Reusing nonlocal addrmode: " << AddrMode << " for "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: Reusing nonlocal addrmode: "
<< AddrMode << " for " << *MemoryInst <<
"\n"; } } while (false)
4313 << *MemoryInst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: Reusing nonlocal addrmode: "
<< AddrMode << " for " << *MemoryInst <<
"\n"; } } while (false)
;
4314 if (SunkAddr->getType() != Addr->getType())
4315 SunkAddr = Builder.CreatePointerCast(SunkAddr, Addr->getType());
4316 } else if (AddrSinkUsingGEPs ||
4317 (!AddrSinkUsingGEPs.getNumOccurrences() && TM && TTI->useAA())) {
4318 // By default, we use the GEP-based method when AA is used later. This
4319 // prevents new inttoptr/ptrtoint pairs from degrading AA capabilities.
4320 DEBUG(dbgs() << "CGP: SINKING nonlocal addrmode: " << AddrMode << " for "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: SINKING nonlocal addrmode: "
<< AddrMode << " for " << *MemoryInst <<
"\n"; } } while (false)
4321 << *MemoryInst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: SINKING nonlocal addrmode: "
<< AddrMode << " for " << *MemoryInst <<
"\n"; } } while (false)
;
4322 Type *IntPtrTy = DL->getIntPtrType(Addr->getType());
4323 Value *ResultPtr = nullptr, *ResultIndex = nullptr;
4324
4325 // First, find the pointer.
4326 if (AddrMode.BaseReg && AddrMode.BaseReg->getType()->isPointerTy()) {
4327 ResultPtr = AddrMode.BaseReg;
4328 AddrMode.BaseReg = nullptr;
4329 }
4330
4331 if (AddrMode.Scale && AddrMode.ScaledReg->getType()->isPointerTy()) {
4332 // We can't add more than one pointer together, nor can we scale a
4333 // pointer (both of which seem meaningless).
4334 if (ResultPtr || AddrMode.Scale != 1)
4335 return false;
4336
4337 ResultPtr = AddrMode.ScaledReg;
4338 AddrMode.Scale = 0;
4339 }
4340
4341 // It is only safe to sign extend the BaseReg if we know that the math
4342 // required to create it did not overflow before we extend it. Since
4343 // the original IR value was tossed in favor of a constant back when
4344 // the AddrMode was created we need to bail out gracefully if widths
4345 // do not match instead of extending it.
4346 //
4347 // (See below for code to add the scale.)
4348 if (AddrMode.Scale) {
4349 Type *ScaledRegTy = AddrMode.ScaledReg->getType();
4350 if (cast<IntegerType>(IntPtrTy)->getBitWidth() >
4351 cast<IntegerType>(ScaledRegTy)->getBitWidth())
4352 return false;
4353 }
4354
4355 if (AddrMode.BaseGV) {
4356 if (ResultPtr)
4357 return false;
4358
4359 ResultPtr = AddrMode.BaseGV;
4360 }
4361
4362 // If the real base value actually came from an inttoptr, then the matcher
4363 // will look through it and provide only the integer value. In that case,
4364 // use it here.
4365 if (!DL->isNonIntegralPointerType(Addr->getType())) {
4366 if (!ResultPtr && AddrMode.BaseReg) {
4367 ResultPtr = Builder.CreateIntToPtr(AddrMode.BaseReg, Addr->getType(),
4368 "sunkaddr");
4369 AddrMode.BaseReg = nullptr;
4370 } else if (!ResultPtr && AddrMode.Scale == 1) {
4371 ResultPtr = Builder.CreateIntToPtr(AddrMode.ScaledReg, Addr->getType(),
4372 "sunkaddr");
4373 AddrMode.Scale = 0;
4374 }
4375 }
4376
4377 if (!ResultPtr &&
4378 !AddrMode.BaseReg && !AddrMode.Scale && !AddrMode.BaseOffs) {
4379 SunkAddr = Constant::getNullValue(Addr->getType());
4380 } else if (!ResultPtr) {
4381 return false;
4382 } else {
4383 Type *I8PtrTy =
4384 Builder.getInt8PtrTy(Addr->getType()->getPointerAddressSpace());
4385 Type *I8Ty = Builder.getInt8Ty();
4386
4387 // Start with the base register. Do this first so that subsequent address
4388 // matching finds it last, which will prevent it from trying to match it
4389 // as the scaled value in case it happens to be a mul. That would be
4390 // problematic if we've sunk a different mul for the scale, because then
4391 // we'd end up sinking both muls.
4392 if (AddrMode.BaseReg) {
4393 Value *V = AddrMode.BaseReg;
4394 if (V->getType() != IntPtrTy)
4395 V = Builder.CreateIntCast(V, IntPtrTy, /*isSigned=*/true, "sunkaddr");
4396
4397 ResultIndex = V;
4398 }
4399
4400 // Add the scale value.
4401 if (AddrMode.Scale) {
4402 Value *V = AddrMode.ScaledReg;
4403 if (V->getType() == IntPtrTy) {
4404 // done.
4405 } else {
4406 assert(cast<IntegerType>(IntPtrTy)->getBitWidth() <(static_cast <bool> (cast<IntegerType>(IntPtrTy)->
getBitWidth() < cast<IntegerType>(V->getType())->
getBitWidth() && "We can't transform if ScaledReg is too narrow"
) ? 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-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 4408, __extension__ __PRETTY_FUNCTION__))
4407 cast<IntegerType>(V->getType())->getBitWidth() &&(static_cast <bool> (cast<IntegerType>(IntPtrTy)->
getBitWidth() < cast<IntegerType>(V->getType())->
getBitWidth() && "We can't transform if ScaledReg is too narrow"
) ? 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-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 4408, __extension__ __PRETTY_FUNCTION__))
4408 "We can't transform if ScaledReg is too narrow")(static_cast <bool> (cast<IntegerType>(IntPtrTy)->
getBitWidth() < cast<IntegerType>(V->getType())->
getBitWidth() && "We can't transform if ScaledReg is too narrow"
) ? 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-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 4408, __extension__ __PRETTY_FUNCTION__))
;
4409 V = Builder.CreateTrunc(V, IntPtrTy, "sunkaddr");
4410 }
4411
4412 if (AddrMode.Scale != 1)
4413 V = Builder.CreateMul(V, ConstantInt::get(IntPtrTy, AddrMode.Scale),
4414 "sunkaddr");
4415 if (ResultIndex)
4416 ResultIndex = Builder.CreateAdd(ResultIndex, V, "sunkaddr");
4417 else
4418 ResultIndex = V;
4419 }
4420
4421 // Add in the Base Offset if present.
4422 if (AddrMode.BaseOffs) {
4423 Value *V = ConstantInt::get(IntPtrTy, AddrMode.BaseOffs);
4424 if (ResultIndex) {
4425 // We need to add this separately from the scale above to help with
4426 // SDAG consecutive load/store merging.
4427 if (ResultPtr->getType() != I8PtrTy)
4428 ResultPtr = Builder.CreatePointerCast(ResultPtr, I8PtrTy);
4429 ResultPtr = Builder.CreateGEP(I8Ty, ResultPtr, ResultIndex, "sunkaddr");
4430 }
4431
4432 ResultIndex = V;
4433 }
4434
4435 if (!ResultIndex) {
4436 SunkAddr = ResultPtr;
4437 } else {
4438 if (ResultPtr->getType() != I8PtrTy)
4439 ResultPtr = Builder.CreatePointerCast(ResultPtr, I8PtrTy);
4440 SunkAddr = Builder.CreateGEP(I8Ty, ResultPtr, ResultIndex, "sunkaddr");
4441 }
4442
4443 if (SunkAddr->getType() != Addr->getType())
4444 SunkAddr = Builder.CreatePointerCast(SunkAddr, Addr->getType());
4445 }
4446 } else {
4447 // We'd require a ptrtoint/inttoptr down the line, which we can't do for
4448 // non-integral pointers, so in that case bail out now.
4449 Type *BaseTy = AddrMode.BaseReg ? AddrMode.BaseReg->getType() : nullptr;
4450 Type *ScaleTy = AddrMode.Scale ? AddrMode.ScaledReg->getType() : nullptr;
4451 PointerType *BasePtrTy = dyn_cast_or_null<PointerType>(BaseTy);
4452 PointerType *ScalePtrTy = dyn_cast_or_null<PointerType>(ScaleTy);
4453 if (DL->isNonIntegralPointerType(Addr->getType()) ||
4454 (BasePtrTy && DL->isNonIntegralPointerType(BasePtrTy)) ||
4455 (ScalePtrTy && DL->isNonIntegralPointerType(ScalePtrTy)) ||
4456 (AddrMode.BaseGV &&
4457 DL->isNonIntegralPointerType(AddrMode.BaseGV->getType())))
4458 return false;
4459
4460 DEBUG(dbgs() << "CGP: SINKING nonlocal addrmode: " << AddrMode << " for "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: SINKING nonlocal addrmode: "
<< AddrMode << " for " << *MemoryInst <<
"\n"; } } while (false)
4461 << *MemoryInst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: SINKING nonlocal addrmode: "
<< AddrMode << " for " << *MemoryInst <<
"\n"; } } while (false)
;
4462 Type *IntPtrTy = DL->getIntPtrType(Addr->getType());
4463 Value *Result = nullptr;
4464
4465 // Start with the base register. Do this first so that subsequent address
4466 // matching finds it last, which will prevent it from trying to match it
4467 // as the scaled value in case it happens to be a mul. That would be
4468 // problematic if we've sunk a different mul for the scale, because then
4469 // we'd end up sinking both muls.
4470 if (AddrMode.BaseReg) {
4471 Value *V = AddrMode.BaseReg;
4472 if (V->getType()->isPointerTy())
4473 V = Builder.CreatePtrToInt(V, IntPtrTy, "sunkaddr");
4474 if (V->getType() != IntPtrTy)
4475 V = Builder.CreateIntCast(V, IntPtrTy, /*isSigned=*/true, "sunkaddr");
4476 Result = V;
4477 }
4478
4479 // Add the scale value.
4480 if (AddrMode.Scale) {
4481 Value *V = AddrMode.ScaledReg;
4482 if (V->getType() == IntPtrTy) {
4483 // done.
4484 } else if (V->getType()->isPointerTy()) {
4485 V = Builder.CreatePtrToInt(V, IntPtrTy, "sunkaddr");
4486 } else if (cast<IntegerType>(IntPtrTy)->getBitWidth() <
4487 cast<IntegerType>(V->getType())->getBitWidth()) {
4488 V = Builder.CreateTrunc(V, IntPtrTy, "sunkaddr");
4489 } else {
4490 // It is only safe to sign extend the BaseReg if we know that the math
4491 // required to create it did not overflow before we extend it. Since
4492 // the original IR value was tossed in favor of a constant back when
4493 // the AddrMode was created we need to bail out gracefully if widths
4494 // do not match instead of extending it.
4495 Instruction *I = dyn_cast_or_null<Instruction>(Result);
4496 if (I && (Result != AddrMode.BaseReg))
4497 I->eraseFromParent();
4498 return false;
4499 }
4500 if (AddrMode.Scale != 1)
4501 V = Builder.CreateMul(V, ConstantInt::get(IntPtrTy, AddrMode.Scale),
4502 "sunkaddr");
4503 if (Result)
4504 Result = Builder.CreateAdd(Result, V, "sunkaddr");
4505 else
4506 Result = V;
4507 }
4508
4509 // Add in the BaseGV if present.
4510 if (AddrMode.BaseGV) {
4511 Value *V = Builder.CreatePtrToInt(AddrMode.BaseGV, IntPtrTy, "sunkaddr");
4512 if (Result)
4513 Result = Builder.CreateAdd(Result, V, "sunkaddr");
4514 else
4515 Result = V;
4516 }
4517
4518 // Add in the Base Offset if present.
4519 if (AddrMode.BaseOffs) {
4520 Value *V = ConstantInt::get(IntPtrTy, AddrMode.BaseOffs);
4521 if (Result)
4522 Result = Builder.CreateAdd(Result, V, "sunkaddr");
4523 else
4524 Result = V;
4525 }
4526
4527 if (!Result)
4528 SunkAddr = Constant::getNullValue(Addr->getType());
4529 else
4530 SunkAddr = Builder.CreateIntToPtr(Result, Addr->getType(), "sunkaddr");
4531 }
4532
4533 MemoryInst->replaceUsesOfWith(Repl, SunkAddr);
4534 // Store the newly computed address into the cache. In the case we reused a
4535 // value, this should be idempotent.
4536 SunkAddrs[Addr] = WeakTrackingVH(SunkAddr);
4537
4538 // If we have no uses, recursively delete the value and all dead instructions
4539 // using it.
4540 if (Repl->use_empty()) {
4541 // This can cause recursive deletion, which can invalidate our iterator.
4542 // Use a WeakTrackingVH to hold onto it in case this happens.
4543 Value *CurValue = &*CurInstIterator;
4544 WeakTrackingVH IterHandle(CurValue);
4545 BasicBlock *BB = CurInstIterator->getParent();
4546
4547 RecursivelyDeleteTriviallyDeadInstructions(Repl, TLInfo);
4548
4549 if (IterHandle != CurValue) {
4550 // If the iterator instruction was recursively deleted, start over at the
4551 // start of the block.
4552 CurInstIterator = BB->begin();
4553 SunkAddrs.clear();
4554 }
4555 }
4556 ++NumMemoryInsts;
4557 return true;
4558}
4559
4560/// If there are any memory operands, use OptimizeMemoryInst to sink their
4561/// address computing into the block when possible / profitable.
4562bool CodeGenPrepare::optimizeInlineAsmInst(CallInst *CS) {
4563 bool MadeChange = false;
4564
4565 const TargetRegisterInfo *TRI =
4566 TM->getSubtargetImpl(*CS->getFunction())->getRegisterInfo();
4567 TargetLowering::AsmOperandInfoVector TargetConstraints =
4568 TLI->ParseConstraints(*DL, TRI, CS);
4569 unsigned ArgNo = 0;
4570 for (unsigned i = 0, e = TargetConstraints.size(); i != e; ++i) {
4571 TargetLowering::AsmOperandInfo &OpInfo = TargetConstraints[i];
4572
4573 // Compute the constraint code and ConstraintType to use.
4574 TLI->ComputeConstraintToUse(OpInfo, SDValue());
4575
4576 if (OpInfo.ConstraintType == TargetLowering::C_Memory &&
4577 OpInfo.isIndirect) {
4578 Value *OpVal = CS->getArgOperand(ArgNo++);
4579 MadeChange |= optimizeMemoryInst(CS, OpVal, OpVal->getType(), ~0u);
4580 } else if (OpInfo.Type == InlineAsm::isInput)
4581 ArgNo++;
4582 }
4583
4584 return MadeChange;
4585}
4586
4587/// \brief Check if all the uses of \p Val are equivalent (or free) zero or
4588/// sign extensions.
4589static bool hasSameExtUse(Value *Val, const TargetLowering &TLI) {
4590 assert(!Val->use_empty() && "Input must have at least one use")(static_cast <bool> (!Val->use_empty() && "Input must have at least one use"
) ? void (0) : __assert_fail ("!Val->use_empty() && \"Input must have at least one use\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 4590, __extension__ __PRETTY_FUNCTION__))
;
4591 const Instruction *FirstUser = cast<Instruction>(*Val->user_begin());
4592 bool IsSExt = isa<SExtInst>(FirstUser);
4593 Type *ExtTy = FirstUser->getType();
4594 for (const User *U : Val->users()) {
4595 const Instruction *UI = cast<Instruction>(U);
4596 if ((IsSExt && !isa<SExtInst>(UI)) || (!IsSExt && !isa<ZExtInst>(UI)))
4597 return false;
4598 Type *CurTy = UI->getType();
4599 // Same input and output types: Same instruction after CSE.
4600 if (CurTy == ExtTy)
4601 continue;
4602
4603 // If IsSExt is true, we are in this situation:
4604 // a = Val
4605 // b = sext ty1 a to ty2
4606 // c = sext ty1 a to ty3
4607 // Assuming ty2 is shorter than ty3, this could be turned into:
4608 // a = Val
4609 // b = sext ty1 a to ty2
4610 // c = sext ty2 b to ty3
4611 // However, the last sext is not free.
4612 if (IsSExt)
4613 return false;
4614
4615 // This is a ZExt, maybe this is free to extend from one type to another.
4616 // In that case, we would not account for a different use.
4617 Type *NarrowTy;
4618 Type *LargeTy;
4619 if (ExtTy->getScalarType()->getIntegerBitWidth() >
4620 CurTy->getScalarType()->getIntegerBitWidth()) {
4621 NarrowTy = CurTy;
4622 LargeTy = ExtTy;
4623 } else {
4624 NarrowTy = ExtTy;
4625 LargeTy = CurTy;
4626 }
4627
4628 if (!TLI.isZExtFree(NarrowTy, LargeTy))
4629 return false;
4630 }
4631 // All uses are the same or can be derived from one another for free.
4632 return true;
4633}
4634
4635/// \brief Try to speculatively promote extensions in \p Exts and continue
4636/// promoting through newly promoted operands recursively as far as doing so is
4637/// profitable. Save extensions profitably moved up, in \p ProfitablyMovedExts.
4638/// When some promotion happened, \p TPT contains the proper state to revert
4639/// them.
4640///
4641/// \return true if some promotion happened, false otherwise.
4642bool CodeGenPrepare::tryToPromoteExts(
4643 TypePromotionTransaction &TPT, const SmallVectorImpl<Instruction *> &Exts,
4644 SmallVectorImpl<Instruction *> &ProfitablyMovedExts,
4645 unsigned CreatedInstsCost) {
4646 bool Promoted = false;
4647
4648 // Iterate over all the extensions to try to promote them.
4649 for (auto I : Exts) {
4650 // Early check if we directly have ext(load).
4651 if (isa<LoadInst>(I->getOperand(0))) {
4652 ProfitablyMovedExts.push_back(I);
4653 continue;
4654 }
4655
4656 // Check whether or not we want to do any promotion. The reason we have
4657 // this check inside the for loop is to catch the case where an extension
4658 // is directly fed by a load because in such case the extension can be moved
4659 // up without any promotion on its operands.
4660 if (!TLI || !TLI->enableExtLdPromotion() || DisableExtLdPromotion)
4661 return false;
4662
4663 // Get the action to perform the promotion.
4664 TypePromotionHelper::Action TPH =
4665 TypePromotionHelper::getAction(I, InsertedInsts, *TLI, PromotedInsts);
4666 // Check if we can promote.
4667 if (!TPH) {
4668 // Save the current extension as we cannot move up through its operand.
4669 ProfitablyMovedExts.push_back(I);
4670 continue;
4671 }
4672
4673 // Save the current state.
4674 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
4675 TPT.getRestorationPoint();
4676 SmallVector<Instruction *, 4> NewExts;
4677 unsigned NewCreatedInstsCost = 0;
4678 unsigned ExtCost = !TLI->isExtFree(I);
4679 // Promote.
4680 Value *PromotedVal = TPH(I, TPT, PromotedInsts, NewCreatedInstsCost,
4681 &NewExts, nullptr, *TLI);
4682 assert(PromotedVal &&(static_cast <bool> (PromotedVal && "TypePromotionHelper should have filtered out those cases"
) ? void (0) : __assert_fail ("PromotedVal && \"TypePromotionHelper should have filtered out those cases\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 4683, __extension__ __PRETTY_FUNCTION__))
4683 "TypePromotionHelper should have filtered out those cases")(static_cast <bool> (PromotedVal && "TypePromotionHelper should have filtered out those cases"
) ? void (0) : __assert_fail ("PromotedVal && \"TypePromotionHelper should have filtered out those cases\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 4683, __extension__ __PRETTY_FUNCTION__))
;
4684
4685 // We would be able to merge only one extension in a load.
4686 // Therefore, if we have more than 1 new extension we heuristically
4687 // cut this search path, because it means we degrade the code quality.
4688 // With exactly 2, the transformation is neutral, because we will merge
4689 // one extension but leave one. However, we optimistically keep going,
4690 // because the new extension may be removed too.
4691 long long TotalCreatedInstsCost = CreatedInstsCost + NewCreatedInstsCost;
4692 // FIXME: It would be possible to propagate a negative value instead of
4693 // conservatively ceiling it to 0.
4694 TotalCreatedInstsCost =
4695 std::max((long long)0, (TotalCreatedInstsCost - ExtCost));
4696 if (!StressExtLdPromotion &&
4697 (TotalCreatedInstsCost > 1 ||
4698 !isPromotedInstructionLegal(*TLI, *DL, PromotedVal))) {
4699 // This promotion is not profitable, rollback to the previous state, and
4700 // save the current extension in ProfitablyMovedExts as the latest
4701 // speculative promotion turned out to be unprofitable.
4702 TPT.rollback(LastKnownGood);
4703 ProfitablyMovedExts.push_back(I);
4704 continue;
4705 }
4706 // Continue promoting NewExts as far as doing so is profitable.
4707 SmallVector<Instruction *, 2> NewlyMovedExts;
4708 (void)tryToPromoteExts(TPT, NewExts, NewlyMovedExts, TotalCreatedInstsCost);
4709 bool NewPromoted = false;
4710 for (auto ExtInst : NewlyMovedExts) {
4711 Instruction *MovedExt = cast<Instruction>(ExtInst);
4712 Value *ExtOperand = MovedExt->getOperand(0);
4713 // If we have reached to a load, we need this extra profitability check
4714 // as it could potentially be merged into an ext(load).
4715 if (isa<LoadInst>(ExtOperand) &&
4716 !(StressExtLdPromotion || NewCreatedInstsCost <= ExtCost ||
4717 (ExtOperand->hasOneUse() || hasSameExtUse(ExtOperand, *TLI))))
4718 continue;
4719
4720 ProfitablyMovedExts.push_back(MovedExt);
4721 NewPromoted = true;
4722 }
4723
4724 // If none of speculative promotions for NewExts is profitable, rollback
4725 // and save the current extension (I) as the last profitable extension.
4726 if (!NewPromoted) {
4727 TPT.rollback(LastKnownGood);
4728 ProfitablyMovedExts.push_back(I);
4729 continue;
4730 }
4731 // The promotion is profitable.
4732 Promoted = true;
4733 }
4734 return Promoted;
4735}
4736
4737/// Merging redundant sexts when one is dominating the other.
4738bool CodeGenPrepare::mergeSExts(Function &F) {
4739 DominatorTree DT(F);
4740 bool Changed = false;
4741 for (auto &Entry : ValToSExtendedUses) {
4742 SExts &Insts = Entry.second;
4743 SExts CurPts;
4744 for (Instruction *Inst : Insts) {
4745 if (RemovedInsts.count(Inst) || !isa<SExtInst>(Inst) ||
4746 Inst->getOperand(0) != Entry.first)
4747 continue;
4748 bool inserted = false;
4749 for (auto &Pt : CurPts) {
4750 if (DT.dominates(Inst, Pt)) {
4751 Pt->replaceAllUsesWith(Inst);
4752 RemovedInsts.insert(Pt);
4753 Pt->removeFromParent();
4754 Pt = Inst;
4755 inserted = true;
4756 Changed = true;
4757 break;
4758 }
4759 if (!DT.dominates(Pt, Inst))
4760 // Give up if we need to merge in a common dominator as the
4761 // expermients show it is not profitable.
4762 continue;
4763 Inst->replaceAllUsesWith(Pt);
4764 RemovedInsts.insert(Inst);
4765 Inst->removeFromParent();
4766 inserted = true;
4767 Changed = true;
4768 break;
4769 }
4770 if (!inserted)
4771 CurPts.push_back(Inst);
4772 }
4773 }
4774 return Changed;
4775}
4776
4777/// Return true, if an ext(load) can be formed from an extension in
4778/// \p MovedExts.
4779bool CodeGenPrepare::canFormExtLd(
4780 const SmallVectorImpl<Instruction *> &MovedExts, LoadInst *&LI,
4781 Instruction *&Inst, bool HasPromoted) {
4782 for (auto *MovedExtInst : MovedExts) {
4783 if (isa<LoadInst>(MovedExtInst->getOperand(0))) {
4784 LI = cast<LoadInst>(MovedExtInst->getOperand(0));
4785 Inst = MovedExtInst;
4786 break;
4787 }
4788 }
4789 if (!LI)
4790 return false;
4791
4792 // If they're already in the same block, there's nothing to do.
4793 // Make the cheap checks first if we did not promote.
4794 // If we promoted, we need to check if it is indeed profitable.
4795 if (!HasPromoted && LI->getParent() == Inst->getParent())
4796 return false;
4797
4798 return TLI->isExtLoad(LI, Inst, *DL);
4799}
4800
4801/// Move a zext or sext fed by a load into the same basic block as the load,
4802/// unless conditions are unfavorable. This allows SelectionDAG to fold the
4803/// extend into the load.
4804///
4805/// E.g.,
4806/// \code
4807/// %ld = load i32* %addr
4808/// %add = add nuw i32 %ld, 4
4809/// %zext = zext i32 %add to i64
4810// \endcode
4811/// =>
4812/// \code
4813/// %ld = load i32* %addr
4814/// %zext = zext i32 %ld to i64
4815/// %add = add nuw i64 %zext, 4
4816/// \encode
4817/// Note that the promotion in %add to i64 is done in tryToPromoteExts(), which
4818/// allow us to match zext(load i32*) to i64.
4819///
4820/// Also, try to promote the computations used to obtain a sign extended
4821/// value used into memory accesses.
4822/// E.g.,
4823/// \code
4824/// a = add nsw i32 b, 3
4825/// d = sext i32 a to i64
4826/// e = getelementptr ..., i64 d
4827/// \endcode
4828/// =>
4829/// \code
4830/// f = sext i32 b to i64
4831/// a = add nsw i64 f, 3
4832/// e = getelementptr ..., i64 a
4833/// \endcode
4834///
4835/// \p Inst[in/out] the extension may be modified during the process if some
4836/// promotions apply.
4837bool CodeGenPrepare::optimizeExt(Instruction *&Inst) {
4838 // ExtLoad formation and address type promotion infrastructure requires TLI to
4839 // be effective.
4840 if (!TLI)
4841 return false;
4842
4843 bool AllowPromotionWithoutCommonHeader = false;
4844 /// See if it is an interesting sext operations for the address type
4845 /// promotion before trying to promote it, e.g., the ones with the right
4846 /// type and used in memory accesses.
4847 bool ATPConsiderable = TTI->shouldConsiderAddressTypePromotion(
4848 *Inst, AllowPromotionWithoutCommonHeader);
4849 TypePromotionTransaction TPT(RemovedInsts);
4850 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
4851 TPT.getRestorationPoint();
4852 SmallVector<Instruction *, 1> Exts;
4853 SmallVector<Instruction *, 2> SpeculativelyMovedExts;
4854 Exts.push_back(Inst);
4855
4856 bool HasPromoted = tryToPromoteExts(TPT, Exts, SpeculativelyMovedExts);
4857
4858 // Look for a load being extended.
4859 LoadInst *LI = nullptr;
4860 Instruction *ExtFedByLoad;
4861
4862 // Try to promote a chain of computation if it allows to form an extended
4863 // load.
4864 if (canFormExtLd(SpeculativelyMovedExts, LI, ExtFedByLoad, HasPromoted)) {
4865 assert(LI && ExtFedByLoad && "Expect a valid load and extension")(static_cast <bool> (LI && ExtFedByLoad &&
"Expect a valid load and extension") ? void (0) : __assert_fail
("LI && ExtFedByLoad && \"Expect a valid load and extension\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 4865, __extension__ __PRETTY_FUNCTION__))
;
4866 TPT.commit();
4867 // Move the extend into the same block as the load
4868 ExtFedByLoad->moveAfter(LI);
4869 // CGP does not check if the zext would be speculatively executed when moved
4870 // to the same basic block as the load. Preserving its original location
4871 // would pessimize the debugging experience, as well as negatively impact
4872 // the quality of sample pgo. We don't want to use "line 0" as that has a
4873 // size cost in the line-table section and logically the zext can be seen as
4874 // part of the load. Therefore we conservatively reuse the same debug
4875 // location for the load and the zext.
4876 ExtFedByLoad->setDebugLoc(LI->getDebugLoc());
4877 ++NumExtsMoved;
4878 Inst = ExtFedByLoad;
4879 return true;
4880 }
4881
4882 // Continue promoting SExts if known as considerable depending on targets.
4883 if (ATPConsiderable &&
4884 performAddressTypePromotion(Inst, AllowPromotionWithoutCommonHeader,
4885 HasPromoted, TPT, SpeculativelyMovedExts))
4886 return true;
4887
4888 TPT.rollback(LastKnownGood);
4889 return false;
4890}
4891
4892// Perform address type promotion if doing so is profitable.
4893// If AllowPromotionWithoutCommonHeader == false, we should find other sext
4894// instructions that sign extended the same initial value. However, if
4895// AllowPromotionWithoutCommonHeader == true, we expect promoting the
4896// extension is just profitable.
4897bool CodeGenPrepare::performAddressTypePromotion(
4898 Instruction *&Inst, bool AllowPromotionWithoutCommonHeader,
4899 bool HasPromoted, TypePromotionTransaction &TPT,
4900 SmallVectorImpl<Instruction *> &SpeculativelyMovedExts) {
4901 bool Promoted = false;
4902 SmallPtrSet<Instruction *, 1> UnhandledExts;
4903 bool AllSeenFirst = true;
4904 for (auto I : SpeculativelyMovedExts) {
4905 Value *HeadOfChain = I->getOperand(0);
4906 DenseMap<Value *, Instruction *>::iterator AlreadySeen =
4907 SeenChainsForSExt.find(HeadOfChain);
4908 // If there is an unhandled SExt which has the same header, try to promote
4909 // it as well.
4910 if (AlreadySeen != SeenChainsForSExt.end()) {
4911 if (AlreadySeen->second != nullptr)
4912 UnhandledExts.insert(AlreadySeen->second);
4913 AllSeenFirst = false;
4914 }
4915 }
4916
4917 if (!AllSeenFirst || (AllowPromotionWithoutCommonHeader &&
4918 SpeculativelyMovedExts.size() == 1)) {
4919 TPT.commit();
4920 if (HasPromoted)
4921 Promoted = true;
4922 for (auto I : SpeculativelyMovedExts) {
4923 Value *HeadOfChain = I->getOperand(0);
4924 SeenChainsForSExt[HeadOfChain] = nullptr;
4925 ValToSExtendedUses[HeadOfChain].push_back(I);
4926 }
4927 // Update Inst as promotion happen.
4928 Inst = SpeculativelyMovedExts.pop_back_val();
4929 } else {
4930 // This is the first chain visited from the header, keep the current chain
4931 // as unhandled. Defer to promote this until we encounter another SExt
4932 // chain derived from the same header.
4933 for (auto I : SpeculativelyMovedExts) {
4934 Value *HeadOfChain = I->getOperand(0);
4935 SeenChainsForSExt[HeadOfChain] = Inst;
4936 }
4937 return false;
4938 }
4939
4940 if (!AllSeenFirst && !UnhandledExts.empty())
4941 for (auto VisitedSExt : UnhandledExts) {
4942 if (RemovedInsts.count(VisitedSExt))
4943 continue;
4944 TypePromotionTransaction TPT(RemovedInsts);
4945 SmallVector<Instruction *, 1> Exts;
4946 SmallVector<Instruction *, 2> Chains;
4947 Exts.push_back(VisitedSExt);
4948 bool HasPromoted = tryToPromoteExts(TPT, Exts, Chains);
4949 TPT.commit();
4950 if (HasPromoted)
4951 Promoted = true;
4952 for (auto I : Chains) {
4953 Value *HeadOfChain = I->getOperand(0);
4954 // Mark this as handled.
4955 SeenChainsForSExt[HeadOfChain] = nullptr;
4956 ValToSExtendedUses[HeadOfChain].push_back(I);
4957 }
4958 }
4959 return Promoted;
4960}
4961
4962bool CodeGenPrepare::optimizeExtUses(Instruction *I) {
4963 BasicBlock *DefBB = I->getParent();
4964
4965 // If the result of a {s|z}ext and its source are both live out, rewrite all
4966 // other uses of the source with result of extension.
4967 Value *Src = I->getOperand(0);
4968 if (Src->hasOneUse())
4969 return false;
4970
4971 // Only do this xform if truncating is free.
4972 if (TLI && !TLI->isTruncateFree(I->getType(), Src->getType()))
4973 return false;
4974
4975 // Only safe to perform the optimization if the source is also defined in
4976 // this block.
4977 if (!isa<Instruction>(Src) || DefBB != cast<Instruction>(Src)->getParent())
4978 return false;
4979
4980 bool DefIsLiveOut = false;
4981 for (User *U : I->users()) {
4982 Instruction *UI = cast<Instruction>(U);
4983
4984 // Figure out which BB this ext is used in.
4985 BasicBlock *UserBB = UI->getParent();
4986 if (UserBB == DefBB) continue;
4987 DefIsLiveOut = true;
4988 break;
4989 }
4990 if (!DefIsLiveOut)
4991 return false;
4992
4993 // Make sure none of the uses are PHI nodes.
4994 for (User *U : Src->users()) {
4995 Instruction *UI = cast<Instruction>(U);
4996 BasicBlock *UserBB = UI->getParent();
4997 if (UserBB == DefBB) continue;
4998 // Be conservative. We don't want this xform to end up introducing
4999 // reloads just before load / store instructions.
5000 if (isa<PHINode>(UI) || isa<LoadInst>(UI) || isa<StoreInst>(UI))
5001 return false;
5002 }
5003
5004 // InsertedTruncs - Only insert one trunc in each block once.
5005 DenseMap<BasicBlock*, Instruction*> InsertedTruncs;
5006
5007 bool MadeChange = false;
5008 for (Use &U : Src->uses()) {
5009 Instruction *User = cast<Instruction>(U.getUser());
5010
5011 // Figure out which BB this ext is used in.
5012 BasicBlock *UserBB = User->getParent();
5013 if (UserBB == DefBB) continue;
5014
5015 // Both src and def are live in this block. Rewrite the use.
5016 Instruction *&InsertedTrunc = InsertedTruncs[UserBB];
5017
5018 if (!InsertedTrunc) {
5019 BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
5020 assert(InsertPt != UserBB->end())(static_cast <bool> (InsertPt != UserBB->end()) ? void
(0) : __assert_fail ("InsertPt != UserBB->end()", "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 5020, __extension__ __PRETTY_FUNCTION__))
;
5021 InsertedTrunc = new TruncInst(I, Src->getType(), "", &*InsertPt);
5022 InsertedInsts.insert(InsertedTrunc);
5023 }
5024
5025 // Replace a use of the {s|z}ext source with a use of the result.
5026 U = InsertedTrunc;
5027 ++NumExtUses;
5028 MadeChange = true;
5029 }
5030
5031 return MadeChange;
5032}
5033
5034// Find loads whose uses only use some of the loaded value's bits. Add an "and"
5035// just after the load if the target can fold this into one extload instruction,
5036// with the hope of eliminating some of the other later "and" instructions using
5037// the loaded value. "and"s that are made trivially redundant by the insertion
5038// of the new "and" are removed by this function, while others (e.g. those whose
5039// path from the load goes through a phi) are left for isel to potentially
5040// remove.
5041//
5042// For example:
5043//
5044// b0:
5045// x = load i32
5046// ...
5047// b1:
5048// y = and x, 0xff
5049// z = use y
5050//
5051// becomes:
5052//
5053// b0:
5054// x = load i32
5055// x' = and x, 0xff
5056// ...
5057// b1:
5058// z = use x'
5059//
5060// whereas:
5061//
5062// b0:
5063// x1 = load i32
5064// ...
5065// b1:
5066// x2 = load i32
5067// ...
5068// b2:
5069// x = phi x1, x2
5070// y = and x, 0xff
5071//
5072// becomes (after a call to optimizeLoadExt for each load):
5073//
5074// b0:
5075// x1 = load i32
5076// x1' = and x1, 0xff
5077// ...
5078// b1:
5079// x2 = load i32
5080// x2' = and x2, 0xff
5081// ...
5082// b2:
5083// x = phi x1', x2'
5084// y = and x, 0xff
5085bool CodeGenPrepare::optimizeLoadExt(LoadInst *Load) {
5086 if (!Load->isSimple() ||
5087 !(Load->getType()->isIntegerTy() || Load->getType()->isPointerTy()))
5088 return false;
5089
5090 // Skip loads we've already transformed.
5091 if (Load->hasOneUse() &&
5092 InsertedInsts.count(cast<Instruction>(*Load->user_begin())))
5093 return false;
5094
5095 // Look at all uses of Load, looking through phis, to determine how many bits
5096 // of the loaded value are needed.
5097 SmallVector<Instruction *, 8> WorkList;
5098 SmallPtrSet<Instruction *, 16> Visited;
5099 SmallVector<Instruction *, 8> AndsToMaybeRemove;
5100 for (auto *U : Load->users())
5101 WorkList.push_back(cast<Instruction>(U));
5102
5103 EVT LoadResultVT = TLI->getValueType(*DL, Load->getType());
5104 unsigned BitWidth = LoadResultVT.getSizeInBits();
5105 APInt DemandBits(BitWidth, 0);
5106 APInt WidestAndBits(BitWidth, 0);
5107
5108 while (!WorkList.empty()) {
5109 Instruction *I = WorkList.back();
5110 WorkList.pop_back();
5111
5112 // Break use-def graph loops.
5113 if (!Visited.insert(I).second)
5114 continue;
5115
5116 // For a PHI node, push all of its users.
5117 if (auto *Phi = dyn_cast<PHINode>(I)) {
5118 for (auto *U : Phi->users())
5119 WorkList.push_back(cast<Instruction>(U));
5120 continue;
5121 }
5122
5123 switch (I->getOpcode()) {
5124 case Instruction::And: {
5125 auto *AndC = dyn_cast<ConstantInt>(I->getOperand(1));
5126 if (!AndC)
5127 return false;
5128 APInt AndBits = AndC->getValue();
5129 DemandBits |= AndBits;
5130 // Keep track of the widest and mask we see.
5131 if (AndBits.ugt(WidestAndBits))
5132 WidestAndBits = AndBits;
5133 if (AndBits == WidestAndBits && I->getOperand(0) == Load)
5134 AndsToMaybeRemove.push_back(I);
5135 break;
5136 }
5137
5138 case Instruction::Shl: {
5139 auto *ShlC = dyn_cast<ConstantInt>(I->getOperand(1));
5140 if (!ShlC)
5141 return false;
5142 uint64_t ShiftAmt = ShlC->getLimitedValue(BitWidth - 1);
5143 DemandBits.setLowBits(BitWidth - ShiftAmt);
5144 break;
5145 }
5146
5147 case Instruction::Trunc: {
5148 EVT TruncVT = TLI->getValueType(*DL, I->getType());
5149 unsigned TruncBitWidth = TruncVT.getSizeInBits();
5150 DemandBits.setLowBits(TruncBitWidth);
5151 break;
5152 }
5153
5154 default:
5155 return false;
5156 }
5157 }
5158
5159 uint32_t ActiveBits = DemandBits.getActiveBits();
5160 // Avoid hoisting (and (load x) 1) since it is unlikely to be folded by the
5161 // target even if isLoadExtLegal says an i1 EXTLOAD is valid. For example,
5162 // for the AArch64 target isLoadExtLegal(ZEXTLOAD, i32, i1) returns true, but
5163 // (and (load x) 1) is not matched as a single instruction, rather as a LDR
5164 // followed by an AND.
5165 // TODO: Look into removing this restriction by fixing backends to either
5166 // return false for isLoadExtLegal for i1 or have them select this pattern to
5167 // a single instruction.
5168 //
5169 // Also avoid hoisting if we didn't see any ands with the exact DemandBits
5170 // mask, since these are the only ands that will be removed by isel.
5171 if (ActiveBits <= 1 || !DemandBits.isMask(ActiveBits) ||
5172 WidestAndBits != DemandBits)
5173 return false;
5174
5175 LLVMContext &Ctx = Load->getType()->getContext();
5176 Type *TruncTy = Type::getIntNTy(Ctx, ActiveBits);
5177 EVT TruncVT = TLI->getValueType(*DL, TruncTy);
5178
5179 // Reject cases that won't be matched as extloads.
5180 if (!LoadResultVT.bitsGT(TruncVT) || !TruncVT.isRound() ||
5181 !TLI->isLoadExtLegal(ISD::ZEXTLOAD, LoadResultVT, TruncVT))
5182 return false;
5183
5184 IRBuilder<> Builder(Load->getNextNode());
5185 auto *NewAnd = dyn_cast<Instruction>(
5186 Builder.CreateAnd(Load, ConstantInt::get(Ctx, DemandBits)));
5187 // Mark this instruction as "inserted by CGP", so that other
5188 // optimizations don't touch it.
5189 InsertedInsts.insert(NewAnd);
5190
5191 // Replace all uses of load with new and (except for the use of load in the
5192 // new and itself).
5193 Load->replaceAllUsesWith(NewAnd);
5194 NewAnd->setOperand(0, Load);
5195
5196 // Remove any and instructions that are now redundant.
5197 for (auto *And : AndsToMaybeRemove)
5198 // Check that the and mask is the same as the one we decided to put on the
5199 // new and.
5200 if (cast<ConstantInt>(And->getOperand(1))->getValue() == DemandBits) {
5201 And->replaceAllUsesWith(NewAnd);
5202 if (&*CurInstIterator == And)
5203 CurInstIterator = std::next(And->getIterator());
5204 And->eraseFromParent();
5205 ++NumAndUses;
5206 }
5207
5208 ++NumAndsAdded;
5209 return true;
5210}
5211
5212/// Check if V (an operand of a select instruction) is an expensive instruction
5213/// that is only used once.
5214static bool sinkSelectOperand(const TargetTransformInfo *TTI, Value *V) {
5215 auto *I = dyn_cast<Instruction>(V);
5216 // If it's safe to speculatively execute, then it should not have side
5217 // effects; therefore, it's safe to sink and possibly *not* execute.
5218 return I && I->hasOneUse() && isSafeToSpeculativelyExecute(I) &&
5219 TTI->getUserCost(I) >= TargetTransformInfo::TCC_Expensive;
5220}
5221
5222/// Returns true if a SelectInst should be turned into an explicit branch.
5223static bool isFormingBranchFromSelectProfitable(const TargetTransformInfo *TTI,
5224 const TargetLowering *TLI,
5225 SelectInst *SI) {
5226 // If even a predictable select is cheap, then a branch can't be cheaper.
5227 if (!TLI->isPredictableSelectExpensive())
5228 return false;
5229
5230 // FIXME: This should use the same heuristics as IfConversion to determine
5231 // whether a select is better represented as a branch.
5232
5233 // If metadata tells us that the select condition is obviously predictable,
5234 // then we want to replace the select with a branch.
5235 uint64_t TrueWeight, FalseWeight;
5236 if (SI->extractProfMetadata(TrueWeight, FalseWeight)) {
5237 uint64_t Max = std::max(TrueWeight, FalseWeight);
5238 uint64_t Sum = TrueWeight + FalseWeight;
5239 if (Sum != 0) {
5240 auto Probability = BranchProbability::getBranchProbability(Max, Sum);
5241 if (Probability > TLI->getPredictableBranchThreshold())
5242 return true;
5243 }
5244 }
5245
5246 CmpInst *Cmp = dyn_cast<CmpInst>(SI->getCondition());
5247
5248 // If a branch is predictable, an out-of-order CPU can avoid blocking on its
5249 // comparison condition. If the compare has more than one use, there's
5250 // probably another cmov or setcc around, so it's not worth emitting a branch.
5251 if (!Cmp || !Cmp->hasOneUse())
5252 return false;
5253
5254 // If either operand of the select is expensive and only needed on one side
5255 // of the select, we should form a branch.
5256 if (sinkSelectOperand(TTI, SI->getTrueValue()) ||
5257 sinkSelectOperand(TTI, SI->getFalseValue()))
5258 return true;
5259
5260 return false;
5261}
5262
5263/// If \p isTrue is true, return the true value of \p SI, otherwise return
5264/// false value of \p SI. If the true/false value of \p SI is defined by any
5265/// select instructions in \p Selects, look through the defining select
5266/// instruction until the true/false value is not defined in \p Selects.
5267static Value *getTrueOrFalseValue(
5268 SelectInst *SI, bool isTrue,
5269 const SmallPtrSet<const Instruction *, 2> &Selects) {
5270 Value *V;
5271
5272 for (SelectInst *DefSI = SI; DefSI != nullptr && Selects.count(DefSI);
5273 DefSI = dyn_cast<SelectInst>(V)) {
5274 assert(DefSI->getCondition() == SI->getCondition() &&(static_cast <bool> (DefSI->getCondition() == SI->
getCondition() && "The condition of DefSI does not match with SI"
) ? void (0) : __assert_fail ("DefSI->getCondition() == SI->getCondition() && \"The condition of DefSI does not match with SI\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 5275, __extension__ __PRETTY_FUNCTION__))
5275 "The condition of DefSI does not match with SI")(static_cast <bool> (DefSI->getCondition() == SI->
getCondition() && "The condition of DefSI does not match with SI"
) ? void (0) : __assert_fail ("DefSI->getCondition() == SI->getCondition() && \"The condition of DefSI does not match with SI\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 5275, __extension__ __PRETTY_FUNCTION__))
;
5276 V = (isTrue ? DefSI->getTrueValue() : DefSI->getFalseValue());
5277 }
5278 return V;
5279}
5280
5281/// If we have a SelectInst that will likely profit from branch prediction,
5282/// turn it into a branch.
5283bool CodeGenPrepare::optimizeSelectInst(SelectInst *SI) {
5284 // Find all consecutive select instructions that share the same condition.
5285 SmallVector<SelectInst *, 2> ASI;
5286 ASI.push_back(SI);
5287 for (BasicBlock::iterator It = ++BasicBlock::iterator(SI);
5288 It != SI->getParent()->end(); ++It) {
5289 SelectInst *I = dyn_cast<SelectInst>(&*It);
5290 if (I && SI->getCondition() == I->getCondition()) {
5291 ASI.push_back(I);
5292 } else {
5293 break;
5294 }
5295 }
5296
5297 SelectInst *LastSI = ASI.back();
5298 // Increment the current iterator to skip all the rest of select instructions
5299 // because they will be either "not lowered" or "all lowered" to branch.
5300 CurInstIterator = std::next(LastSI->getIterator());
5301
5302 bool VectorCond = !SI->getCondition()->getType()->isIntegerTy(1);
5303
5304 // Can we convert the 'select' to CF ?
5305 if (DisableSelectToBranch || OptSize || !TLI || VectorCond ||
5306 SI->getMetadata(LLVMContext::MD_unpredictable))
5307 return false;
5308
5309 TargetLowering::SelectSupportKind SelectKind;
5310 if (VectorCond)
5311 SelectKind = TargetLowering::VectorMaskSelect;
5312 else if (SI->getType()->isVectorTy())
5313 SelectKind = TargetLowering::ScalarCondVectorVal;
5314 else
5315 SelectKind = TargetLowering::ScalarValSelect;
5316
5317 if (TLI->isSelectSupported(SelectKind) &&
5318 !isFormingBranchFromSelectProfitable(TTI, TLI, SI))
5319 return false;
5320
5321 ModifiedDT = true;
5322
5323 // Transform a sequence like this:
5324 // start:
5325 // %cmp = cmp uge i32 %a, %b
5326 // %sel = select i1 %cmp, i32 %c, i32 %d
5327 //
5328 // Into:
5329 // start:
5330 // %cmp = cmp uge i32 %a, %b
5331 // br i1 %cmp, label %select.true, label %select.false
5332 // select.true:
5333 // br label %select.end
5334 // select.false:
5335 // br label %select.end
5336 // select.end:
5337 // %sel = phi i32 [ %c, %select.true ], [ %d, %select.false ]
5338 //
5339 // In addition, we may sink instructions that produce %c or %d from
5340 // the entry block into the destination(s) of the new branch.
5341 // If the true or false blocks do not contain a sunken instruction, that
5342 // block and its branch may be optimized away. In that case, one side of the
5343 // first branch will point directly to select.end, and the corresponding PHI
5344 // predecessor block will be the start block.
5345
5346 // First, we split the block containing the select into 2 blocks.
5347 BasicBlock *StartBlock = SI->getParent();
5348 BasicBlock::iterator SplitPt = ++(BasicBlock::iterator(LastSI));
5349 BasicBlock *EndBlock = StartBlock->splitBasicBlock(SplitPt, "select.end");
5350
5351 // Delete the unconditional branch that was just created by the split.
5352 StartBlock->getTerminator()->eraseFromParent();
5353
5354 // These are the new basic blocks for the conditional branch.
5355 // At least one will become an actual new basic block.
5356 BasicBlock *TrueBlock = nullptr;
5357 BasicBlock *FalseBlock = nullptr;
5358 BranchInst *TrueBranch = nullptr;
5359 BranchInst *FalseBranch = nullptr;
5360
5361 // Sink expensive instructions into the conditional blocks to avoid executing
5362 // them speculatively.
5363 for (SelectInst *SI : ASI) {
5364 if (sinkSelectOperand(TTI, SI->getTrueValue())) {
5365 if (TrueBlock == nullptr) {
5366 TrueBlock = BasicBlock::Create(SI->getContext(), "select.true.sink",
5367 EndBlock->getParent(), EndBlock);
5368 TrueBranch = BranchInst::Create(EndBlock, TrueBlock);
5369 }
5370 auto *TrueInst = cast<Instruction>(SI->getTrueValue());
5371 TrueInst->moveBefore(TrueBranch);
5372 }
5373 if (sinkSelectOperand(TTI, SI->getFalseValue())) {
5374 if (FalseBlock == nullptr) {
5375 FalseBlock = BasicBlock::Create(SI->getContext(), "select.false.sink",
5376 EndBlock->getParent(), EndBlock);
5377 FalseBranch = BranchInst::Create(EndBlock, FalseBlock);
5378 }
5379 auto *FalseInst = cast<Instruction>(SI->getFalseValue());
5380 FalseInst->moveBefore(FalseBranch);
5381 }
5382 }
5383
5384 // If there was nothing to sink, then arbitrarily choose the 'false' side
5385 // for a new input value to the PHI.
5386 if (TrueBlock == FalseBlock) {
5387 assert(TrueBlock == nullptr &&(static_cast <bool> (TrueBlock == nullptr && "Unexpected basic block transform while optimizing select"
) ? void (0) : __assert_fail ("TrueBlock == nullptr && \"Unexpected basic block transform while optimizing select\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 5388, __extension__ __PRETTY_FUNCTION__))
5388 "Unexpected basic block transform while optimizing select")(static_cast <bool> (TrueBlock == nullptr && "Unexpected basic block transform while optimizing select"
) ? void (0) : __assert_fail ("TrueBlock == nullptr && \"Unexpected basic block transform while optimizing select\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 5388, __extension__ __PRETTY_FUNCTION__))
;
5389
5390 FalseBlock = BasicBlock::Create(SI->getContext(), "select.false",
5391 EndBlock->getParent(), EndBlock);
5392 BranchInst::Create(EndBlock, FalseBlock);
5393 }
5394
5395 // Insert the real conditional branch based on the original condition.
5396 // If we did not create a new block for one of the 'true' or 'false' paths
5397 // of the condition, it means that side of the branch goes to the end block
5398 // directly and the path originates from the start block from the point of
5399 // view of the new PHI.
5400 BasicBlock *TT, *FT;
5401 if (TrueBlock == nullptr) {
5402 TT = EndBlock;
5403 FT = FalseBlock;
5404 TrueBlock = StartBlock;
5405 } else if (FalseBlock == nullptr) {
5406 TT = TrueBlock;
5407 FT = EndBlock;
5408 FalseBlock = StartBlock;
5409 } else {
5410 TT = TrueBlock;
5411 FT = FalseBlock;
5412 }
5413 IRBuilder<>(SI).CreateCondBr(SI->getCondition(), TT, FT, SI);
5414
5415 SmallPtrSet<const Instruction *, 2> INS;
5416 INS.insert(ASI.begin(), ASI.end());
5417 // Use reverse iterator because later select may use the value of the
5418 // earlier select, and we need to propagate value through earlier select
5419 // to get the PHI operand.
5420 for (auto It = ASI.rbegin(); It != ASI.rend(); ++It) {
5421 SelectInst *SI = *It;
5422 // The select itself is replaced with a PHI Node.
5423 PHINode *PN = PHINode::Create(SI->getType(), 2, "", &EndBlock->front());
5424 PN->takeName(SI);
5425 PN->addIncoming(getTrueOrFalseValue(SI, true, INS), TrueBlock);
5426 PN->addIncoming(getTrueOrFalseValue(SI, false, INS), FalseBlock);
5427
5428 SI->replaceAllUsesWith(PN);
5429 SI->eraseFromParent();
5430 INS.erase(SI);
5431 ++NumSelectsExpanded;
5432 }
5433
5434 // Instruct OptimizeBlock to skip to the next block.
5435 CurInstIterator = StartBlock->end();
5436 return true;
5437}
5438
5439static bool isBroadcastShuffle(ShuffleVectorInst *SVI) {
5440 SmallVector<int, 16> Mask(SVI->getShuffleMask());
5441 int SplatElem = -1;
5442 for (unsigned i = 0; i < Mask.size(); ++i) {
5443 if (SplatElem != -1 && Mask[i] != -1 && Mask[i] != SplatElem)
5444 return false;
5445 SplatElem = Mask[i];
5446 }
5447
5448 return true;
5449}
5450
5451/// Some targets have expensive vector shifts if the lanes aren't all the same
5452/// (e.g. x86 only introduced "vpsllvd" and friends with AVX2). In these cases
5453/// it's often worth sinking a shufflevector splat down to its use so that
5454/// codegen can spot all lanes are identical.
5455bool CodeGenPrepare::optimizeShuffleVectorInst(ShuffleVectorInst *SVI) {
5456 BasicBlock *DefBB = SVI->getParent();
5457
5458 // Only do this xform if variable vector shifts are particularly expensive.
5459 if (!TLI || !TLI->isVectorShiftByScalarCheap(SVI->getType()))
5460 return false;
5461
5462 // We only expect better codegen by sinking a shuffle if we can recognise a
5463 // constant splat.
5464 if (!isBroadcastShuffle(SVI))
5465 return false;
5466
5467 // InsertedShuffles - Only insert a shuffle in each block once.
5468 DenseMap<BasicBlock*, Instruction*> InsertedShuffles;
5469
5470 bool MadeChange = false;
5471 for (User *U : SVI->users()) {
5472 Instruction *UI = cast<Instruction>(U);
5473
5474 // Figure out which BB this ext is used in.
5475 BasicBlock *UserBB = UI->getParent();
5476 if (UserBB == DefBB) continue;
5477
5478 // For now only apply this when the splat is used by a shift instruction.
5479 if (!UI->isShift()) continue;
5480
5481 // Everything checks out, sink the shuffle if the user's block doesn't
5482 // already have a copy.
5483 Instruction *&InsertedShuffle = InsertedShuffles[UserBB];
5484
5485 if (!InsertedShuffle) {
5486 BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
5487 assert(InsertPt != UserBB->end())(static_cast <bool> (InsertPt != UserBB->end()) ? void
(0) : __assert_fail ("InsertPt != UserBB->end()", "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 5487, __extension__ __PRETTY_FUNCTION__))
;
5488 InsertedShuffle =
5489 new ShuffleVectorInst(SVI->getOperand(0), SVI->getOperand(1),
5490 SVI->getOperand(2), "", &*InsertPt);
5491 }
5492
5493 UI->replaceUsesOfWith(SVI, InsertedShuffle);
5494 MadeChange = true;
5495 }
5496
5497 // If we removed all uses, nuke the shuffle.
5498 if (SVI->use_empty()) {
5499 SVI->eraseFromParent();
5500 MadeChange = true;
5501 }
5502
5503 return MadeChange;
5504}
5505
5506bool CodeGenPrepare::optimizeSwitchInst(SwitchInst *SI) {
5507 if (!TLI || !DL)
5508 return false;
5509
5510 Value *Cond = SI->getCondition();
5511 Type *OldType = Cond->getType();
5512 LLVMContext &Context = Cond->getContext();
5513 MVT RegType = TLI->getRegisterType(Context, TLI->getValueType(*DL, OldType));
5514 unsigned RegWidth = RegType.getSizeInBits();
5515
5516 if (RegWidth <= cast<IntegerType>(OldType)->getBitWidth())
5517 return false;
5518
5519 // If the register width is greater than the type width, expand the condition
5520 // of the switch instruction and each case constant to the width of the
5521 // register. By widening the type of the switch condition, subsequent
5522 // comparisons (for case comparisons) will not need to be extended to the
5523 // preferred register width, so we will potentially eliminate N-1 extends,
5524 // where N is the number of cases in the switch.
5525 auto *NewType = Type::getIntNTy(Context, RegWidth);
5526
5527 // Zero-extend the switch condition and case constants unless the switch
5528 // condition is a function argument that is already being sign-extended.
5529 // In that case, we can avoid an unnecessary mask/extension by sign-extending
5530 // everything instead.
5531 Instruction::CastOps ExtType = Instruction::ZExt;
5532 if (auto *Arg = dyn_cast<Argument>(Cond))
5533 if (Arg->hasSExtAttr())
5534 ExtType = Instruction::SExt;
5535
5536 auto *ExtInst = CastInst::Create(ExtType, Cond, NewType);
5537 ExtInst->insertBefore(SI);
5538 SI->setCondition(ExtInst);
5539 for (auto Case : SI->cases()) {
5540 APInt NarrowConst = Case.getCaseValue()->getValue();
5541 APInt WideConst = (ExtType == Instruction::ZExt) ?
5542 NarrowConst.zext(RegWidth) : NarrowConst.sext(RegWidth);
5543 Case.setValue(ConstantInt::get(Context, WideConst));
5544 }
5545
5546 return true;
5547}
5548
5549
5550namespace {
5551
5552/// \brief Helper class to promote a scalar operation to a vector one.
5553/// This class is used to move downward extractelement transition.
5554/// E.g.,
5555/// a = vector_op <2 x i32>
5556/// b = extractelement <2 x i32> a, i32 0
5557/// c = scalar_op b
5558/// store c
5559///
5560/// =>
5561/// a = vector_op <2 x i32>
5562/// c = vector_op a (equivalent to scalar_op on the related lane)
5563/// * d = extractelement <2 x i32> c, i32 0
5564/// * store d
5565/// Assuming both extractelement and store can be combine, we get rid of the
5566/// transition.
5567class VectorPromoteHelper {
5568 /// DataLayout associated with the current module.
5569 const DataLayout &DL;
5570
5571 /// Used to perform some checks on the legality of vector operations.
5572 const TargetLowering &TLI;
5573
5574 /// Used to estimated the cost of the promoted chain.
5575 const TargetTransformInfo &TTI;
5576
5577 /// The transition being moved downwards.
5578 Instruction *Transition;
5579
5580 /// The sequence of instructions to be promoted.
5581 SmallVector<Instruction *, 4> InstsToBePromoted;
5582
5583 /// Cost of combining a store and an extract.
5584 unsigned StoreExtractCombineCost;
5585
5586 /// Instruction that will be combined with the transition.
5587 Instruction *CombineInst = nullptr;
5588
5589 /// \brief The instruction that represents the current end of the transition.
5590 /// Since we are faking the promotion until we reach the end of the chain
5591 /// of computation, we need a way to get the current end of the transition.
5592 Instruction *getEndOfTransition() const {
5593 if (InstsToBePromoted.empty())
5594 return Transition;
5595 return InstsToBePromoted.back();
5596 }
5597
5598 /// \brief Return the index of the original value in the transition.
5599 /// E.g., for "extractelement <2 x i32> c, i32 1" the original value,
5600 /// c, is at index 0.
5601 unsigned getTransitionOriginalValueIdx() const {
5602 assert(isa<ExtractElementInst>(Transition) &&(static_cast <bool> (isa<ExtractElementInst>(Transition
) && "Other kind of transitions are not supported yet"
) ? void (0) : __assert_fail ("isa<ExtractElementInst>(Transition) && \"Other kind of transitions are not supported yet\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 5603, __extension__ __PRETTY_FUNCTION__))
5603 "Other kind of transitions are not supported yet")(static_cast <bool> (isa<ExtractElementInst>(Transition
) && "Other kind of transitions are not supported yet"
) ? void (0) : __assert_fail ("isa<ExtractElementInst>(Transition) && \"Other kind of transitions are not supported yet\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 5603, __extension__ __PRETTY_FUNCTION__))
;
5604 return 0;
5605 }
5606
5607 /// \brief Return the index of the index in the transition.
5608 /// E.g., for "extractelement <2 x i32> c, i32 0" the index
5609 /// is at index 1.
5610 unsigned getTransitionIdx() const {
5611 assert(isa<ExtractElementInst>(Transition) &&(static_cast <bool> (isa<ExtractElementInst>(Transition
) && "Other kind of transitions are not supported yet"
) ? void (0) : __assert_fail ("isa<ExtractElementInst>(Transition) && \"Other kind of transitions are not supported yet\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 5612, __extension__ __PRETTY_FUNCTION__))
5612 "Other kind of transitions are not supported yet")(static_cast <bool> (isa<ExtractElementInst>(Transition
) && "Other kind of transitions are not supported yet"
) ? void (0) : __assert_fail ("isa<ExtractElementInst>(Transition) && \"Other kind of transitions are not supported yet\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 5612, __extension__ __PRETTY_FUNCTION__))
;
5613 return 1;
5614 }
5615
5616 /// \brief Get the type of the transition.
5617 /// This is the type of the original value.
5618 /// E.g., for "extractelement <2 x i32> c, i32 1" the type of the
5619 /// transition is <2 x i32>.
5620 Type *getTransitionType() const {
5621 return Transition->getOperand(getTransitionOriginalValueIdx())->getType();
5622 }
5623
5624 /// \brief Promote \p ToBePromoted by moving \p Def downward through.
5625 /// I.e., we have the following sequence:
5626 /// Def = Transition <ty1> a to <ty2>
5627 /// b = ToBePromoted <ty2> Def, ...
5628 /// =>
5629 /// b = ToBePromoted <ty1> a, ...
5630 /// Def = Transition <ty1> ToBePromoted to <ty2>
5631 void promoteImpl(Instruction *ToBePromoted);
5632
5633 /// \brief Check whether or not it is profitable to promote all the
5634 /// instructions enqueued to be promoted.
5635 bool isProfitableToPromote() {
5636 Value *ValIdx = Transition->getOperand(getTransitionOriginalValueIdx());
5637 unsigned Index = isa<ConstantInt>(ValIdx)
5638 ? cast<ConstantInt>(ValIdx)->getZExtValue()
5639 : -1;
5640 Type *PromotedType = getTransitionType();
5641
5642 StoreInst *ST = cast<StoreInst>(CombineInst);
5643 unsigned AS = ST->getPointerAddressSpace();
5644 unsigned Align = ST->getAlignment();
5645 // Check if this store is supported.
5646 if (!TLI.allowsMisalignedMemoryAccesses(
5647 TLI.getValueType(DL, ST->getValueOperand()->getType()), AS,
5648 Align)) {
5649 // If this is not supported, there is no way we can combine
5650 // the extract with the store.
5651 return false;
5652 }
5653
5654 // The scalar chain of computation has to pay for the transition
5655 // scalar to vector.
5656 // The vector chain has to account for the combining cost.
5657 uint64_t ScalarCost =
5658 TTI.getVectorInstrCost(Transition->getOpcode(), PromotedType, Index);
5659 uint64_t VectorCost = StoreExtractCombineCost;
5660 for (const auto &Inst : InstsToBePromoted) {
5661 // Compute the cost.
5662 // By construction, all instructions being promoted are arithmetic ones.
5663 // Moreover, one argument is a constant that can be viewed as a splat
5664 // constant.
5665 Value *Arg0 = Inst->getOperand(0);
5666 bool IsArg0Constant = isa<UndefValue>(Arg0) || isa<ConstantInt>(Arg0) ||
5667 isa<ConstantFP>(Arg0);
5668 TargetTransformInfo::OperandValueKind Arg0OVK =
5669 IsArg0Constant ? TargetTransformInfo::OK_UniformConstantValue
5670 : TargetTransformInfo::OK_AnyValue;
5671 TargetTransformInfo::OperandValueKind Arg1OVK =
5672 !IsArg0Constant ? TargetTransformInfo::OK_UniformConstantValue
5673 : TargetTransformInfo::OK_AnyValue;
5674 ScalarCost += TTI.getArithmeticInstrCost(
5675 Inst->getOpcode(), Inst->getType(), Arg0OVK, Arg1OVK);
5676 VectorCost += TTI.getArithmeticInstrCost(Inst->getOpcode(), PromotedType,
5677 Arg0OVK, Arg1OVK);
5678 }
5679 DEBUG(dbgs() << "Estimated cost of computation to be promoted:\nScalar: "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Estimated cost of computation to be promoted:\nScalar: "
<< ScalarCost << "\nVector: " << VectorCost
<< '\n'; } } while (false)
5680 << ScalarCost << "\nVector: " << VectorCost << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Estimated cost of computation to be promoted:\nScalar: "
<< ScalarCost << "\nVector: " << VectorCost
<< '\n'; } } while (false)
;
5681 return ScalarCost > VectorCost;
5682 }
5683
5684 /// \brief Generate a constant vector with \p Val with the same
5685 /// number of elements as the transition.
5686 /// \p UseSplat defines whether or not \p Val should be replicated
5687 /// across the whole vector.
5688 /// In other words, if UseSplat == true, we generate <Val, Val, ..., Val>,
5689 /// otherwise we generate a vector with as many undef as possible:
5690 /// <undef, ..., undef, Val, undef, ..., undef> where \p Val is only
5691 /// used at the index of the extract.
5692 Value *getConstantVector(Constant *Val, bool UseSplat) const {
5693 unsigned ExtractIdx = std::numeric_limits<unsigned>::max();
5694 if (!UseSplat) {
5695 // If we cannot determine where the constant must be, we have to
5696 // use a splat constant.
5697 Value *ValExtractIdx = Transition->getOperand(getTransitionIdx());
5698 if (ConstantInt *CstVal = dyn_cast<ConstantInt>(ValExtractIdx))
5699 ExtractIdx = CstVal->getSExtValue();
5700 else
5701 UseSplat = true;
5702 }
5703
5704 unsigned End = getTransitionType()->getVectorNumElements();
5705 if (UseSplat)
5706 return ConstantVector::getSplat(End, Val);
5707
5708 SmallVector<Constant *, 4> ConstVec;
5709 UndefValue *UndefVal = UndefValue::get(Val->getType());
5710 for (unsigned Idx = 0; Idx != End; ++Idx) {
5711 if (Idx == ExtractIdx)
5712 ConstVec.push_back(Val);
5713 else
5714 ConstVec.push_back(UndefVal);
5715 }
5716 return ConstantVector::get(ConstVec);
5717 }
5718
5719 /// \brief Check if promoting to a vector type an operand at \p OperandIdx
5720 /// in \p Use can trigger undefined behavior.
5721 static bool canCauseUndefinedBehavior(const Instruction *Use,
5722 unsigned OperandIdx) {
5723 // This is not safe to introduce undef when the operand is on
5724 // the right hand side of a division-like instruction.
5725 if (OperandIdx != 1)
5726 return false;
5727 switch (Use->getOpcode()) {
5728 default:
5729 return false;
5730 case Instruction::SDiv:
5731 case Instruction::UDiv:
5732 case Instruction::SRem:
5733 case Instruction::URem:
5734 return true;
5735 case Instruction::FDiv:
5736 case Instruction::FRem:
5737 return !Use->hasNoNaNs();
5738 }
5739 llvm_unreachable(nullptr)::llvm::llvm_unreachable_internal(nullptr, "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 5739)
;
5740 }
5741
5742public:
5743 VectorPromoteHelper(const DataLayout &DL, const TargetLowering &TLI,
5744 const TargetTransformInfo &TTI, Instruction *Transition,
5745 unsigned CombineCost)
5746 : DL(DL), TLI(TLI), TTI(TTI), Transition(Transition),
5747 StoreExtractCombineCost(CombineCost) {
5748 assert(Transition && "Do not know how to promote null")(static_cast <bool> (Transition && "Do not know how to promote null"
) ? void (0) : __assert_fail ("Transition && \"Do not know how to promote null\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 5748, __extension__ __PRETTY_FUNCTION__))
;
5749 }
5750
5751 /// \brief Check if we can promote \p ToBePromoted to \p Type.
5752 bool canPromote(const Instruction *ToBePromoted) const {
5753 // We could support CastInst too.
5754 return isa<BinaryOperator>(ToBePromoted);
5755 }
5756
5757 /// \brief Check if it is profitable to promote \p ToBePromoted
5758 /// by moving downward the transition through.
5759 bool shouldPromote(const Instruction *ToBePromoted) const {
5760 // Promote only if all the operands can be statically expanded.
5761 // Indeed, we do not want to introduce any new kind of transitions.
5762 for (const Use &U : ToBePromoted->operands()) {
5763 const Value *Val = U.get();
5764 if (Val == getEndOfTransition()) {
5765 // If the use is a division and the transition is on the rhs,
5766 // we cannot promote the operation, otherwise we may create a
5767 // division by zero.
5768 if (canCauseUndefinedBehavior(ToBePromoted, U.getOperandNo()))
5769 return false;
5770 continue;
5771 }
5772 if (!isa<ConstantInt>(Val) && !isa<UndefValue>(Val) &&
5773 !isa<ConstantFP>(Val))
5774 return false;
5775 }
5776 // Check that the resulting operation is legal.
5777 int ISDOpcode = TLI.InstructionOpcodeToISD(ToBePromoted->getOpcode());
5778 if (!ISDOpcode)
5779 return false;
5780 return StressStoreExtract ||
5781 TLI.isOperationLegalOrCustom(
5782 ISDOpcode, TLI.getValueType(DL, getTransitionType(), true));
5783 }
5784
5785 /// \brief Check whether or not \p Use can be combined
5786 /// with the transition.
5787 /// I.e., is it possible to do Use(Transition) => AnotherUse?
5788 bool canCombine(const Instruction *Use) { return isa<StoreInst>(Use); }
5789
5790 /// \brief Record \p ToBePromoted as part of the chain to be promoted.
5791 void enqueueForPromotion(Instruction *ToBePromoted) {
5792 InstsToBePromoted.push_back(ToBePromoted);
5793 }
5794
5795 /// \brief Set the instruction that will be combined with the transition.
5796 void recordCombineInstruction(Instruction *ToBeCombined) {
5797 assert(canCombine(ToBeCombined) && "Unsupported instruction to combine")(static_cast <bool> (canCombine(ToBeCombined) &&
"Unsupported instruction to combine") ? void (0) : __assert_fail
("canCombine(ToBeCombined) && \"Unsupported instruction to combine\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/CodeGen/CodeGenPrepare.cpp"
, 5797, __extension__ __PRETTY_FUNCTION__))
;
5798 CombineInst = ToBeCombined;
5799 }
5800
5801