Bug Summary

File:llvm/lib/CodeGen/CodeGenPrepare.cpp
Warning:line 4173, column 20
Called C++ object pointer is null

Annotated Source Code

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clang -cc1 -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name CodeGenPrepare.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -analyzer-config-compatibility-mode=true -mrelocation-model pic -pic-level 2 -mframe-pointer=none -fmath-errno -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -ffunction-sections -fdata-sections -fcoverage-compilation-dir=/build/llvm-toolchain-snapshot-14~++20220116100644+5f782d25a742/build-llvm -resource-dir /usr/lib/llvm-14/lib/clang/14.0.0 -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I lib/CodeGen -I /build/llvm-toolchain-snapshot-14~++20220116100644+5f782d25a742/llvm/lib/CodeGen -I include -I /build/llvm-toolchain-snapshot-14~++20220116100644+5f782d25a742/llvm/include -D _FORTIFY_SOURCE=2 -D NDEBUG -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/x86_64-linux-gnu/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/backward -internal-isystem /usr/lib/llvm-14/lib/clang/14.0.0/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../x86_64-linux-gnu/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -fmacro-prefix-map=/build/llvm-toolchain-snapshot-14~++20220116100644+5f782d25a742/build-llvm=build-llvm -fmacro-prefix-map=/build/llvm-toolchain-snapshot-14~++20220116100644+5f782d25a742/= -fcoverage-prefix-map=/build/llvm-toolchain-snapshot-14~++20220116100644+5f782d25a742/build-llvm=build-llvm -fcoverage-prefix-map=/build/llvm-toolchain-snapshot-14~++20220116100644+5f782d25a742/= -O3 -Wno-unused-command-line-argument -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-class-memaccess -Wno-redundant-move -Wno-pessimizing-move -Wno-noexcept-type -Wno-comment -std=c++14 -fdeprecated-macro -fdebug-compilation-dir=/build/llvm-toolchain-snapshot-14~++20220116100644+5f782d25a742/build-llvm -fdebug-prefix-map=/build/llvm-toolchain-snapshot-14~++20220116100644+5f782d25a742/build-llvm=build-llvm -fdebug-prefix-map=/build/llvm-toolchain-snapshot-14~++20220116100644+5f782d25a742/= -ferror-limit 19 -fvisibility-inlines-hidden -stack-protector 2 -fgnuc-version=4.2.1 -fcolor-diagnostics -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/scan-build-2022-01-16-232930-107970-1 -x c++ /build/llvm-toolchain-snapshot-14~++20220116100644+5f782d25a742/llvm/lib/CodeGen/CodeGenPrepare.cpp

/build/llvm-toolchain-snapshot-14~++20220116100644+5f782d25a742/llvm/lib/CodeGen/CodeGenPrepare.cpp

1//===- CodeGenPrepare.cpp - Prepare a function for code generation --------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This pass munges the code in the input function to better prepare it for
10// SelectionDAG-based code generation. This works around limitations in it's
11// basic-block-at-a-time approach. It should eventually be removed.
12//
13//===----------------------------------------------------------------------===//
14
15#include "llvm/ADT/APInt.h"
16#include "llvm/ADT/ArrayRef.h"
17#include "llvm/ADT/DenseMap.h"
18#include "llvm/ADT/MapVector.h"
19#include "llvm/ADT/PointerIntPair.h"
20#include "llvm/ADT/STLExtras.h"
21#include "llvm/ADT/SmallPtrSet.h"
22#include "llvm/ADT/SmallVector.h"
23#include "llvm/ADT/Statistic.h"
24#include "llvm/Analysis/BlockFrequencyInfo.h"
25#include "llvm/Analysis/BranchProbabilityInfo.h"
26#include "llvm/Analysis/ConstantFolding.h"
27#include "llvm/Analysis/InstructionSimplify.h"
28#include "llvm/Analysis/LoopInfo.h"
29#include "llvm/Analysis/MemoryBuiltins.h"
30#include "llvm/Analysis/ProfileSummaryInfo.h"
31#include "llvm/Analysis/TargetLibraryInfo.h"
32#include "llvm/Analysis/TargetTransformInfo.h"
33#include "llvm/Analysis/ValueTracking.h"
34#include "llvm/Analysis/VectorUtils.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/Config/llvm-config.h"
43#include "llvm/IR/Argument.h"
44#include "llvm/IR/Attributes.h"
45#include "llvm/IR/BasicBlock.h"
46#include "llvm/IR/Constant.h"
47#include "llvm/IR/Constants.h"
48#include "llvm/IR/DataLayout.h"
49#include "llvm/IR/DebugInfo.h"
50#include "llvm/IR/DerivedTypes.h"
51#include "llvm/IR/Dominators.h"
52#include "llvm/IR/Function.h"
53#include "llvm/IR/GetElementPtrTypeIterator.h"
54#include "llvm/IR/GlobalValue.h"
55#include "llvm/IR/GlobalVariable.h"
56#include "llvm/IR/IRBuilder.h"
57#include "llvm/IR/InlineAsm.h"
58#include "llvm/IR/InstrTypes.h"
59#include "llvm/IR/Instruction.h"
60#include "llvm/IR/Instructions.h"
61#include "llvm/IR/IntrinsicInst.h"
62#include "llvm/IR/Intrinsics.h"
63#include "llvm/IR/IntrinsicsAArch64.h"
64#include "llvm/IR/LLVMContext.h"
65#include "llvm/IR/MDBuilder.h"
66#include "llvm/IR/Module.h"
67#include "llvm/IR/Operator.h"
68#include "llvm/IR/PatternMatch.h"
69#include "llvm/IR/Statepoint.h"
70#include "llvm/IR/Type.h"
71#include "llvm/IR/Use.h"
72#include "llvm/IR/User.h"
73#include "llvm/IR/Value.h"
74#include "llvm/IR/ValueHandle.h"
75#include "llvm/IR/ValueMap.h"
76#include "llvm/InitializePasses.h"
77#include "llvm/Pass.h"
78#include "llvm/Support/BlockFrequency.h"
79#include "llvm/Support/BranchProbability.h"
80#include "llvm/Support/Casting.h"
81#include "llvm/Support/CommandLine.h"
82#include "llvm/Support/Compiler.h"
83#include "llvm/Support/Debug.h"
84#include "llvm/Support/ErrorHandling.h"
85#include "llvm/Support/MachineValueType.h"
86#include "llvm/Support/MathExtras.h"
87#include "llvm/Support/raw_ostream.h"
88#include "llvm/Target/TargetMachine.h"
89#include "llvm/Target/TargetOptions.h"
90#include "llvm/Transforms/Utils/BasicBlockUtils.h"
91#include "llvm/Transforms/Utils/BypassSlowDivision.h"
92#include "llvm/Transforms/Utils/Local.h"
93#include "llvm/Transforms/Utils/SimplifyLibCalls.h"
94#include "llvm/Transforms/Utils/SizeOpts.h"
95#include <algorithm>
96#include <cassert>
97#include <cstdint>
98#include <iterator>
99#include <limits>
100#include <memory>
101#include <utility>
102#include <vector>
103
104using namespace llvm;
105using namespace llvm::PatternMatch;
106
107#define DEBUG_TYPE"codegenprepare" "codegenprepare"
108
109STATISTIC(NumBlocksElim, "Number of blocks eliminated")static llvm::Statistic NumBlocksElim = {"codegenprepare", "NumBlocksElim"
, "Number of blocks eliminated"}
;
110STATISTIC(NumPHIsElim, "Number of trivial PHIs eliminated")static llvm::Statistic NumPHIsElim = {"codegenprepare", "NumPHIsElim"
, "Number of trivial PHIs eliminated"}
;
111STATISTIC(NumGEPsElim, "Number of GEPs converted to casts")static llvm::Statistic NumGEPsElim = {"codegenprepare", "NumGEPsElim"
, "Number of GEPs converted to casts"}
;
112STATISTIC(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"
}
113 "sunken Cmps")static llvm::Statistic NumCmpUses = {"codegenprepare", "NumCmpUses"
, "Number of uses of Cmp expressions replaced with uses of " "sunken Cmps"
}
;
114STATISTIC(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"
}
115 "of sunken Casts")static llvm::Statistic NumCastUses = {"codegenprepare", "NumCastUses"
, "Number of uses of Cast expressions replaced with uses " "of sunken Casts"
}
;
116STATISTIC(NumMemoryInsts, "Number of memory instructions whose address "static llvm::Statistic NumMemoryInsts = {"codegenprepare", "NumMemoryInsts"
, "Number of memory instructions whose address " "computations were sunk"
}
117 "computations were sunk")static llvm::Statistic NumMemoryInsts = {"codegenprepare", "NumMemoryInsts"
, "Number of memory instructions whose address " "computations were sunk"
}
;
118STATISTIC(NumMemoryInstsPhiCreated,static llvm::Statistic NumMemoryInstsPhiCreated = {"codegenprepare"
, "NumMemoryInstsPhiCreated", "Number of phis created when address "
"computations were sunk to memory instructions"}
119 "Number of phis created when address "static llvm::Statistic NumMemoryInstsPhiCreated = {"codegenprepare"
, "NumMemoryInstsPhiCreated", "Number of phis created when address "
"computations were sunk to memory instructions"}
120 "computations were sunk to memory instructions")static llvm::Statistic NumMemoryInstsPhiCreated = {"codegenprepare"
, "NumMemoryInstsPhiCreated", "Number of phis created when address "
"computations were sunk to memory instructions"}
;
121STATISTIC(NumMemoryInstsSelectCreated,static llvm::Statistic NumMemoryInstsSelectCreated = {"codegenprepare"
, "NumMemoryInstsSelectCreated", "Number of select created when address "
"computations were sunk to memory instructions"}
122 "Number of select created when address "static llvm::Statistic NumMemoryInstsSelectCreated = {"codegenprepare"
, "NumMemoryInstsSelectCreated", "Number of select created when address "
"computations were sunk to memory instructions"}
123 "computations were sunk to memory instructions")static llvm::Statistic NumMemoryInstsSelectCreated = {"codegenprepare"
, "NumMemoryInstsSelectCreated", "Number of select created when address "
"computations were sunk to memory instructions"}
;
124STATISTIC(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"}
;
125STATISTIC(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"}
;
126STATISTIC(NumAndsAdded,static llvm::Statistic NumAndsAdded = {"codegenprepare", "NumAndsAdded"
, "Number of and mask instructions added to form ext loads"}
127 "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"}
;
128STATISTIC(NumAndUses, "Number of uses of and mask instructions optimized")static llvm::Statistic NumAndUses = {"codegenprepare", "NumAndUses"
, "Number of uses of and mask instructions optimized"}
;
129STATISTIC(NumRetsDup, "Number of return instructions duplicated")static llvm::Statistic NumRetsDup = {"codegenprepare", "NumRetsDup"
, "Number of return instructions duplicated"}
;
130STATISTIC(NumDbgValueMoved, "Number of debug value instructions moved")static llvm::Statistic NumDbgValueMoved = {"codegenprepare", "NumDbgValueMoved"
, "Number of debug value instructions moved"}
;
131STATISTIC(NumSelectsExpanded, "Number of selects turned into branches")static llvm::Statistic NumSelectsExpanded = {"codegenprepare"
, "NumSelectsExpanded", "Number of selects turned into branches"
}
;
132STATISTIC(NumStoreExtractExposed, "Number of store(extractelement) exposed")static llvm::Statistic NumStoreExtractExposed = {"codegenprepare"
, "NumStoreExtractExposed", "Number of store(extractelement) exposed"
}
;
133
134static cl::opt<bool> DisableBranchOpts(
135 "disable-cgp-branch-opts", cl::Hidden, cl::init(false),
136 cl::desc("Disable branch optimizations in CodeGenPrepare"));
137
138static cl::opt<bool>
139 DisableGCOpts("disable-cgp-gc-opts", cl::Hidden, cl::init(false),
140 cl::desc("Disable GC optimizations in CodeGenPrepare"));
141
142static cl::opt<bool> DisableSelectToBranch(
143 "disable-cgp-select2branch", cl::Hidden, cl::init(false),
144 cl::desc("Disable select to branch conversion."));
145
146static cl::opt<bool> AddrSinkUsingGEPs(
147 "addr-sink-using-gep", cl::Hidden, cl::init(true),
148 cl::desc("Address sinking in CGP using GEPs."));
149
150static cl::opt<bool> EnableAndCmpSinking(
151 "enable-andcmp-sinking", cl::Hidden, cl::init(true),
152 cl::desc("Enable sinkinig and/cmp into branches."));
153
154static cl::opt<bool> DisableStoreExtract(
155 "disable-cgp-store-extract", cl::Hidden, cl::init(false),
156 cl::desc("Disable store(extract) optimizations in CodeGenPrepare"));
157
158static cl::opt<bool> StressStoreExtract(
159 "stress-cgp-store-extract", cl::Hidden, cl::init(false),
160 cl::desc("Stress test store(extract) optimizations in CodeGenPrepare"));
161
162static cl::opt<bool> DisableExtLdPromotion(
163 "disable-cgp-ext-ld-promotion", cl::Hidden, cl::init(false),
164 cl::desc("Disable ext(promotable(ld)) -> promoted(ext(ld)) optimization in "
165 "CodeGenPrepare"));
166
167static cl::opt<bool> StressExtLdPromotion(
168 "stress-cgp-ext-ld-promotion", cl::Hidden, cl::init(false),
169 cl::desc("Stress test ext(promotable(ld)) -> promoted(ext(ld)) "
170 "optimization in CodeGenPrepare"));
171
172static cl::opt<bool> DisablePreheaderProtect(
173 "disable-preheader-prot", cl::Hidden, cl::init(false),
174 cl::desc("Disable protection against removing loop preheaders"));
175
176static cl::opt<bool> ProfileGuidedSectionPrefix(
177 "profile-guided-section-prefix", cl::Hidden, cl::init(true), cl::ZeroOrMore,
178 cl::desc("Use profile info to add section prefix for hot/cold functions"));
179
180static cl::opt<bool> ProfileUnknownInSpecialSection(
181 "profile-unknown-in-special-section", cl::Hidden, cl::init(false),
182 cl::ZeroOrMore,
183 cl::desc("In profiling mode like sampleFDO, if a function doesn't have "
184 "profile, we cannot tell the function is cold for sure because "
185 "it may be a function newly added without ever being sampled. "
186 "With the flag enabled, compiler can put such profile unknown "
187 "functions into a special section, so runtime system can choose "
188 "to handle it in a different way than .text section, to save "
189 "RAM for example. "));
190
191static cl::opt<unsigned> FreqRatioToSkipMerge(
192 "cgp-freq-ratio-to-skip-merge", cl::Hidden, cl::init(2),
193 cl::desc("Skip merging empty blocks if (frequency of empty block) / "
194 "(frequency of destination block) is greater than this ratio"));
195
196static cl::opt<bool> ForceSplitStore(
197 "force-split-store", cl::Hidden, cl::init(false),
198 cl::desc("Force store splitting no matter what the target query says."));
199
200static cl::opt<bool>
201EnableTypePromotionMerge("cgp-type-promotion-merge", cl::Hidden,
202 cl::desc("Enable merging of redundant sexts when one is dominating"
203 " the other."), cl::init(true));
204
205static cl::opt<bool> DisableComplexAddrModes(
206 "disable-complex-addr-modes", cl::Hidden, cl::init(false),
207 cl::desc("Disables combining addressing modes with different parts "
208 "in optimizeMemoryInst."));
209
210static cl::opt<bool>
211AddrSinkNewPhis("addr-sink-new-phis", cl::Hidden, cl::init(false),
212 cl::desc("Allow creation of Phis in Address sinking."));
213
214static cl::opt<bool>
215AddrSinkNewSelects("addr-sink-new-select", cl::Hidden, cl::init(true),
216 cl::desc("Allow creation of selects in Address sinking."));
217
218static cl::opt<bool> AddrSinkCombineBaseReg(
219 "addr-sink-combine-base-reg", cl::Hidden, cl::init(true),
220 cl::desc("Allow combining of BaseReg field in Address sinking."));
221
222static cl::opt<bool> AddrSinkCombineBaseGV(
223 "addr-sink-combine-base-gv", cl::Hidden, cl::init(true),
224 cl::desc("Allow combining of BaseGV field in Address sinking."));
225
226static cl::opt<bool> AddrSinkCombineBaseOffs(
227 "addr-sink-combine-base-offs", cl::Hidden, cl::init(true),
228 cl::desc("Allow combining of BaseOffs field in Address sinking."));
229
230static cl::opt<bool> AddrSinkCombineScaledReg(
231 "addr-sink-combine-scaled-reg", cl::Hidden, cl::init(true),
232 cl::desc("Allow combining of ScaledReg field in Address sinking."));
233
234static cl::opt<bool>
235 EnableGEPOffsetSplit("cgp-split-large-offset-gep", cl::Hidden,
236 cl::init(true),
237 cl::desc("Enable splitting large offset of GEP."));
238
239static cl::opt<bool> EnableICMP_EQToICMP_ST(
240 "cgp-icmp-eq2icmp-st", cl::Hidden, cl::init(false),
241 cl::desc("Enable ICMP_EQ to ICMP_S(L|G)T conversion."));
242
243static cl::opt<bool>
244 VerifyBFIUpdates("cgp-verify-bfi-updates", cl::Hidden, cl::init(false),
245 cl::desc("Enable BFI update verification for "
246 "CodeGenPrepare."));
247
248static cl::opt<bool> OptimizePhiTypes(
249 "cgp-optimize-phi-types", cl::Hidden, cl::init(false),
250 cl::desc("Enable converting phi types in CodeGenPrepare"));
251
252namespace {
253
254enum ExtType {
255 ZeroExtension, // Zero extension has been seen.
256 SignExtension, // Sign extension has been seen.
257 BothExtension // This extension type is used if we saw sext after
258 // ZeroExtension had been set, or if we saw zext after
259 // SignExtension had been set. It makes the type
260 // information of a promoted instruction invalid.
261};
262
263using SetOfInstrs = SmallPtrSet<Instruction *, 16>;
264using TypeIsSExt = PointerIntPair<Type *, 2, ExtType>;
265using InstrToOrigTy = DenseMap<Instruction *, TypeIsSExt>;
266using SExts = SmallVector<Instruction *, 16>;
267using ValueToSExts = DenseMap<Value *, SExts>;
268
269class TypePromotionTransaction;
270
271 class CodeGenPrepare : public FunctionPass {
272 const TargetMachine *TM = nullptr;
273 const TargetSubtargetInfo *SubtargetInfo;
274 const TargetLowering *TLI = nullptr;
275 const TargetRegisterInfo *TRI;
276 const TargetTransformInfo *TTI = nullptr;
277 const TargetLibraryInfo *TLInfo;
278 const LoopInfo *LI;
279 std::unique_ptr<BlockFrequencyInfo> BFI;
280 std::unique_ptr<BranchProbabilityInfo> BPI;
281 ProfileSummaryInfo *PSI;
282
283 /// As we scan instructions optimizing them, this is the next instruction
284 /// to optimize. Transforms that can invalidate this should update it.
285 BasicBlock::iterator CurInstIterator;
286
287 /// Keeps track of non-local addresses that have been sunk into a block.
288 /// This allows us to avoid inserting duplicate code for blocks with
289 /// multiple load/stores of the same address. The usage of WeakTrackingVH
290 /// enables SunkAddrs to be treated as a cache whose entries can be
291 /// invalidated if a sunken address computation has been erased.
292 ValueMap<Value*, WeakTrackingVH> SunkAddrs;
293
294 /// Keeps track of all instructions inserted for the current function.
295 SetOfInstrs InsertedInsts;
296
297 /// Keeps track of the type of the related instruction before their
298 /// promotion for the current function.
299 InstrToOrigTy PromotedInsts;
300
301 /// Keep track of instructions removed during promotion.
302 SetOfInstrs RemovedInsts;
303
304 /// Keep track of sext chains based on their initial value.
305 DenseMap<Value *, Instruction *> SeenChainsForSExt;
306
307 /// Keep track of GEPs accessing the same data structures such as structs or
308 /// arrays that are candidates to be split later because of their large
309 /// size.
310 MapVector<
311 AssertingVH<Value>,
312 SmallVector<std::pair<AssertingVH<GetElementPtrInst>, int64_t>, 32>>
313 LargeOffsetGEPMap;
314
315 /// Keep track of new GEP base after splitting the GEPs having large offset.
316 SmallSet<AssertingVH<Value>, 2> NewGEPBases;
317
318 /// Map serial numbers to Large offset GEPs.
319 DenseMap<AssertingVH<GetElementPtrInst>, int> LargeOffsetGEPID;
320
321 /// Keep track of SExt promoted.
322 ValueToSExts ValToSExtendedUses;
323
324 /// True if the function has the OptSize attribute.
325 bool OptSize;
326
327 /// DataLayout for the Function being processed.
328 const DataLayout *DL = nullptr;
329
330 /// Building the dominator tree can be expensive, so we only build it
331 /// lazily and update it when required.
332 std::unique_ptr<DominatorTree> DT;
333
334 public:
335 static char ID; // Pass identification, replacement for typeid
336
337 CodeGenPrepare() : FunctionPass(ID) {
338 initializeCodeGenPreparePass(*PassRegistry::getPassRegistry());
339 }
340
341 bool runOnFunction(Function &F) override;
342
343 StringRef getPassName() const override { return "CodeGen Prepare"; }
344
345 void getAnalysisUsage(AnalysisUsage &AU) const override {
346 // FIXME: When we can selectively preserve passes, preserve the domtree.
347 AU.addRequired<ProfileSummaryInfoWrapperPass>();
348 AU.addRequired<TargetLibraryInfoWrapperPass>();
349 AU.addRequired<TargetPassConfig>();
350 AU.addRequired<TargetTransformInfoWrapperPass>();
351 AU.addRequired<LoopInfoWrapperPass>();
352 }
353
354 private:
355 template <typename F>
356 void resetIteratorIfInvalidatedWhileCalling(BasicBlock *BB, F f) {
357 // Substituting can cause recursive simplifications, which can invalidate
358 // our iterator. Use a WeakTrackingVH to hold onto it in case this
359 // happens.
360 Value *CurValue = &*CurInstIterator;
361 WeakTrackingVH IterHandle(CurValue);
362
363 f();
364
365 // If the iterator instruction was recursively deleted, start over at the
366 // start of the block.
367 if (IterHandle != CurValue) {
368 CurInstIterator = BB->begin();
369 SunkAddrs.clear();
370 }
371 }
372
373 // Get the DominatorTree, building if necessary.
374 DominatorTree &getDT(Function &F) {
375 if (!DT)
376 DT = std::make_unique<DominatorTree>(F);
377 return *DT;
378 }
379
380 void removeAllAssertingVHReferences(Value *V);
381 bool eliminateAssumptions(Function &F);
382 bool eliminateFallThrough(Function &F);
383 bool eliminateMostlyEmptyBlocks(Function &F);
384 BasicBlock *findDestBlockOfMergeableEmptyBlock(BasicBlock *BB);
385 bool canMergeBlocks(const BasicBlock *BB, const BasicBlock *DestBB) const;
386 void eliminateMostlyEmptyBlock(BasicBlock *BB);
387 bool isMergingEmptyBlockProfitable(BasicBlock *BB, BasicBlock *DestBB,
388 bool isPreheader);
389 bool makeBitReverse(Instruction &I);
390 bool optimizeBlock(BasicBlock &BB, bool &ModifiedDT);
391 bool optimizeInst(Instruction *I, bool &ModifiedDT);
392 bool optimizeMemoryInst(Instruction *MemoryInst, Value *Addr,
393 Type *AccessTy, unsigned AddrSpace);
394 bool optimizeGatherScatterInst(Instruction *MemoryInst, Value *Ptr);
395 bool optimizeInlineAsmInst(CallInst *CS);
396 bool optimizeCallInst(CallInst *CI, bool &ModifiedDT);
397 bool optimizeExt(Instruction *&I);
398 bool optimizeExtUses(Instruction *I);
399 bool optimizeLoadExt(LoadInst *Load);
400 bool optimizeShiftInst(BinaryOperator *BO);
401 bool optimizeFunnelShift(IntrinsicInst *Fsh);
402 bool optimizeSelectInst(SelectInst *SI);
403 bool optimizeShuffleVectorInst(ShuffleVectorInst *SVI);
404 bool optimizeSwitchInst(SwitchInst *SI);
405 bool optimizeExtractElementInst(Instruction *Inst);
406 bool dupRetToEnableTailCallOpts(BasicBlock *BB, bool &ModifiedDT);
407 bool fixupDbgValue(Instruction *I);
408 bool placeDbgValues(Function &F);
409 bool placePseudoProbes(Function &F);
410 bool canFormExtLd(const SmallVectorImpl<Instruction *> &MovedExts,
411 LoadInst *&LI, Instruction *&Inst, bool HasPromoted);
412 bool tryToPromoteExts(TypePromotionTransaction &TPT,
413 const SmallVectorImpl<Instruction *> &Exts,
414 SmallVectorImpl<Instruction *> &ProfitablyMovedExts,
415 unsigned CreatedInstsCost = 0);
416 bool mergeSExts(Function &F);
417 bool splitLargeGEPOffsets();
418 bool optimizePhiType(PHINode *Inst, SmallPtrSetImpl<PHINode *> &Visited,
419 SmallPtrSetImpl<Instruction *> &DeletedInstrs);
420 bool optimizePhiTypes(Function &F);
421 bool performAddressTypePromotion(
422 Instruction *&Inst,
423 bool AllowPromotionWithoutCommonHeader,
424 bool HasPromoted, TypePromotionTransaction &TPT,
425 SmallVectorImpl<Instruction *> &SpeculativelyMovedExts);
426 bool splitBranchCondition(Function &F, bool &ModifiedDT);
427 bool simplifyOffsetableRelocate(GCStatepointInst &I);
428
429 bool tryToSinkFreeOperands(Instruction *I);
430 bool replaceMathCmpWithIntrinsic(BinaryOperator *BO, Value *Arg0,
431 Value *Arg1, CmpInst *Cmp,
432 Intrinsic::ID IID);
433 bool optimizeCmp(CmpInst *Cmp, bool &ModifiedDT);
434 bool combineToUSubWithOverflow(CmpInst *Cmp, bool &ModifiedDT);
435 bool combineToUAddWithOverflow(CmpInst *Cmp, bool &ModifiedDT);
436 void verifyBFIUpdates(Function &F);
437 };
438
439} // end anonymous namespace
440
441char CodeGenPrepare::ID = 0;
442
443INITIALIZE_PASS_BEGIN(CodeGenPrepare, DEBUG_TYPE,static void *initializeCodeGenPreparePassOnce(PassRegistry &
Registry) {
444 "Optimize for code generation", false, false)static void *initializeCodeGenPreparePassOnce(PassRegistry &
Registry) {
445INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)initializeLoopInfoWrapperPassPass(Registry);
446INITIALIZE_PASS_DEPENDENCY(ProfileSummaryInfoWrapperPass)initializeProfileSummaryInfoWrapperPassPass(Registry);
447INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)initializeTargetLibraryInfoWrapperPassPass(Registry);
448INITIALIZE_PASS_DEPENDENCY(TargetPassConfig)initializeTargetPassConfigPass(Registry);
449INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)initializeTargetTransformInfoWrapperPassPass(Registry);
450INITIALIZE_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)); }
451 "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)); }
452
453FunctionPass *llvm::createCodeGenPreparePass() { return new CodeGenPrepare(); }
454
455bool CodeGenPrepare::runOnFunction(Function &F) {
456 if (skipFunction(F))
457 return false;
458
459 DL = &F.getParent()->getDataLayout();
460
461 bool EverMadeChange = false;
462 // Clear per function information.
463 InsertedInsts.clear();
464 PromotedInsts.clear();
465
466 TM = &getAnalysis<TargetPassConfig>().getTM<TargetMachine>();
467 SubtargetInfo = TM->getSubtargetImpl(F);
468 TLI = SubtargetInfo->getTargetLowering();
469 TRI = SubtargetInfo->getRegisterInfo();
470 TLInfo = &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(F);
471 TTI = &getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
472 LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
473 BPI.reset(new BranchProbabilityInfo(F, *LI));
474 BFI.reset(new BlockFrequencyInfo(F, *BPI, *LI));
475 PSI = &getAnalysis<ProfileSummaryInfoWrapperPass>().getPSI();
476 OptSize = F.hasOptSize();
477 if (ProfileGuidedSectionPrefix) {
478 // The hot attribute overwrites profile count based hotness while profile
479 // counts based hotness overwrite the cold attribute.
480 // This is a conservative behabvior.
481 if (F.hasFnAttribute(Attribute::Hot) ||
482 PSI->isFunctionHotInCallGraph(&F, *BFI))
483 F.setSectionPrefix("hot");
484 // If PSI shows this function is not hot, we will placed the function
485 // into unlikely section if (1) PSI shows this is a cold function, or
486 // (2) the function has a attribute of cold.
487 else if (PSI->isFunctionColdInCallGraph(&F, *BFI) ||
488 F.hasFnAttribute(Attribute::Cold))
489 F.setSectionPrefix("unlikely");
490 else if (ProfileUnknownInSpecialSection && PSI->hasPartialSampleProfile() &&
491 PSI->isFunctionHotnessUnknown(F))
492 F.setSectionPrefix("unknown");
493 }
494
495 /// This optimization identifies DIV instructions that can be
496 /// profitably bypassed and carried out with a shorter, faster divide.
497 if (!OptSize && !PSI->hasHugeWorkingSetSize() && TLI->isSlowDivBypassed()) {
498 const DenseMap<unsigned int, unsigned int> &BypassWidths =
499 TLI->getBypassSlowDivWidths();
500 BasicBlock* BB = &*F.begin();
501 while (BB != nullptr) {
502 // bypassSlowDivision may create new BBs, but we don't want to reapply the
503 // optimization to those blocks.
504 BasicBlock* Next = BB->getNextNode();
505 // F.hasOptSize is already checked in the outer if statement.
506 if (!llvm::shouldOptimizeForSize(BB, PSI, BFI.get()))
507 EverMadeChange |= bypassSlowDivision(BB, BypassWidths);
508 BB = Next;
509 }
510 }
511
512 // Get rid of @llvm.assume builtins before attempting to eliminate empty
513 // blocks, since there might be blocks that only contain @llvm.assume calls
514 // (plus arguments that we can get rid of).
515 EverMadeChange |= eliminateAssumptions(F);
516
517 // Eliminate blocks that contain only PHI nodes and an
518 // unconditional branch.
519 EverMadeChange |= eliminateMostlyEmptyBlocks(F);
520
521 bool ModifiedDT = false;
522 if (!DisableBranchOpts)
523 EverMadeChange |= splitBranchCondition(F, ModifiedDT);
524
525 // Split some critical edges where one of the sources is an indirect branch,
526 // to help generate sane code for PHIs involving such edges.
527 EverMadeChange |= SplitIndirectBrCriticalEdges(F);
528
529 bool MadeChange = true;
530 while (MadeChange) {
531 MadeChange = false;
532 DT.reset();
533 for (BasicBlock &BB : llvm::make_early_inc_range(F)) {
534 bool ModifiedDTOnIteration = false;
535 MadeChange |= optimizeBlock(BB, ModifiedDTOnIteration);
536
537 // Restart BB iteration if the dominator tree of the Function was changed
538 if (ModifiedDTOnIteration)
539 break;
540 }
541 if (EnableTypePromotionMerge && !ValToSExtendedUses.empty())
542 MadeChange |= mergeSExts(F);
543 if (!LargeOffsetGEPMap.empty())
544 MadeChange |= splitLargeGEPOffsets();
545 MadeChange |= optimizePhiTypes(F);
546
547 if (MadeChange)
548 eliminateFallThrough(F);
549
550 // Really free removed instructions during promotion.
551 for (Instruction *I : RemovedInsts)
552 I->deleteValue();
553
554 EverMadeChange |= MadeChange;
555 SeenChainsForSExt.clear();
556 ValToSExtendedUses.clear();
557 RemovedInsts.clear();
558 LargeOffsetGEPMap.clear();
559 LargeOffsetGEPID.clear();
560 }
561
562 NewGEPBases.clear();
563 SunkAddrs.clear();
564
565 if (!DisableBranchOpts) {
566 MadeChange = false;
567 // Use a set vector to get deterministic iteration order. The order the
568 // blocks are removed may affect whether or not PHI nodes in successors
569 // are removed.
570 SmallSetVector<BasicBlock*, 8> WorkList;
571 for (BasicBlock &BB : F) {
572 SmallVector<BasicBlock *, 2> Successors(successors(&BB));
573 MadeChange |= ConstantFoldTerminator(&BB, true);
574 if (!MadeChange) continue;
575
576 for (BasicBlock *Succ : Successors)
577 if (pred_empty(Succ))
578 WorkList.insert(Succ);
579 }
580
581 // Delete the dead blocks and any of their dead successors.
582 MadeChange |= !WorkList.empty();
583 while (!WorkList.empty()) {
584 BasicBlock *BB = WorkList.pop_back_val();
585 SmallVector<BasicBlock*, 2> Successors(successors(BB));
586
587 DeleteDeadBlock(BB);
588
589 for (BasicBlock *Succ : Successors)
590 if (pred_empty(Succ))
591 WorkList.insert(Succ);
592 }
593
594 // Merge pairs of basic blocks with unconditional branches, connected by
595 // a single edge.
596 if (EverMadeChange || MadeChange)
597 MadeChange |= eliminateFallThrough(F);
598
599 EverMadeChange |= MadeChange;
600 }
601
602 if (!DisableGCOpts) {
603 SmallVector<GCStatepointInst *, 2> Statepoints;
604 for (BasicBlock &BB : F)
605 for (Instruction &I : BB)
606 if (auto *SP = dyn_cast<GCStatepointInst>(&I))
607 Statepoints.push_back(SP);
608 for (auto &I : Statepoints)
609 EverMadeChange |= simplifyOffsetableRelocate(*I);
610 }
611
612 // Do this last to clean up use-before-def scenarios introduced by other
613 // preparatory transforms.
614 EverMadeChange |= placeDbgValues(F);
615 EverMadeChange |= placePseudoProbes(F);
616
617#ifndef NDEBUG
618 if (VerifyBFIUpdates)
619 verifyBFIUpdates(F);
620#endif
621
622 return EverMadeChange;
623}
624
625bool CodeGenPrepare::eliminateAssumptions(Function &F) {
626 bool MadeChange = false;
627 for (BasicBlock &BB : F) {
628 CurInstIterator = BB.begin();
629 while (CurInstIterator != BB.end()) {
630 Instruction *I = &*(CurInstIterator++);
631 if (auto *Assume = dyn_cast<AssumeInst>(I)) {
632 MadeChange = true;
633 Value *Operand = Assume->getOperand(0);
634 Assume->eraseFromParent();
635
636 resetIteratorIfInvalidatedWhileCalling(&BB, [&]() {
637 RecursivelyDeleteTriviallyDeadInstructions(Operand, TLInfo, nullptr);
638 });
639 }
640 }
641 }
642 return MadeChange;
643}
644
645/// An instruction is about to be deleted, so remove all references to it in our
646/// GEP-tracking data strcutures.
647void CodeGenPrepare::removeAllAssertingVHReferences(Value *V) {
648 LargeOffsetGEPMap.erase(V);
649 NewGEPBases.erase(V);
650
651 auto GEP = dyn_cast<GetElementPtrInst>(V);
652 if (!GEP)
653 return;
654
655 LargeOffsetGEPID.erase(GEP);
656
657 auto VecI = LargeOffsetGEPMap.find(GEP->getPointerOperand());
658 if (VecI == LargeOffsetGEPMap.end())
659 return;
660
661 auto &GEPVector = VecI->second;
662 llvm::erase_if(GEPVector, [=](auto &Elt) { return Elt.first == GEP; });
663
664 if (GEPVector.empty())
665 LargeOffsetGEPMap.erase(VecI);
666}
667
668// Verify BFI has been updated correctly by recomputing BFI and comparing them.
669void LLVM_ATTRIBUTE_UNUSED__attribute__((__unused__)) CodeGenPrepare::verifyBFIUpdates(Function &F) {
670 DominatorTree NewDT(F);
671 LoopInfo NewLI(NewDT);
672 BranchProbabilityInfo NewBPI(F, NewLI, TLInfo);
673 BlockFrequencyInfo NewBFI(F, NewBPI, NewLI);
674 NewBFI.verifyMatch(*BFI);
675}
676
677/// Merge basic blocks which are connected by a single edge, where one of the
678/// basic blocks has a single successor pointing to the other basic block,
679/// which has a single predecessor.
680bool CodeGenPrepare::eliminateFallThrough(Function &F) {
681 bool Changed = false;
682 // Scan all of the blocks in the function, except for the entry block.
683 // Use a temporary array to avoid iterator being invalidated when
684 // deleting blocks.
685 SmallVector<WeakTrackingVH, 16> Blocks;
686 for (auto &Block : llvm::drop_begin(F))
687 Blocks.push_back(&Block);
688
689 SmallSet<WeakTrackingVH, 16> Preds;
690 for (auto &Block : Blocks) {
691 auto *BB = cast_or_null<BasicBlock>(Block);
692 if (!BB)
693 continue;
694 // If the destination block has a single pred, then this is a trivial
695 // edge, just collapse it.
696 BasicBlock *SinglePred = BB->getSinglePredecessor();
697
698 // Don't merge if BB's address is taken.
699 if (!SinglePred || SinglePred == BB || BB->hasAddressTaken()) continue;
700
701 BranchInst *Term = dyn_cast<BranchInst>(SinglePred->getTerminator());
702 if (Term && !Term->isConditional()) {
703 Changed = true;
704 LLVM_DEBUG(dbgs() << "To merge:\n" << *BB << "\n\n\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "To merge:\n" << *
BB << "\n\n\n"; } } while (false)
;
705
706 // Merge BB into SinglePred and delete it.
707 MergeBlockIntoPredecessor(BB);
708 Preds.insert(SinglePred);
709 }
710 }
711
712 // (Repeatedly) merging blocks into their predecessors can create redundant
713 // debug intrinsics.
714 for (auto &Pred : Preds)
715 if (auto *BB = cast_or_null<BasicBlock>(Pred))
716 RemoveRedundantDbgInstrs(BB);
717
718 return Changed;
719}
720
721/// Find a destination block from BB if BB is mergeable empty block.
722BasicBlock *CodeGenPrepare::findDestBlockOfMergeableEmptyBlock(BasicBlock *BB) {
723 // If this block doesn't end with an uncond branch, ignore it.
724 BranchInst *BI = dyn_cast<BranchInst>(BB->getTerminator());
725 if (!BI || !BI->isUnconditional())
726 return nullptr;
727
728 // If the instruction before the branch (skipping debug info) isn't a phi
729 // node, then other stuff is happening here.
730 BasicBlock::iterator BBI = BI->getIterator();
731 if (BBI != BB->begin()) {
732 --BBI;
733 while (isa<DbgInfoIntrinsic>(BBI)) {
734 if (BBI == BB->begin())
735 break;
736 --BBI;
737 }
738 if (!isa<DbgInfoIntrinsic>(BBI) && !isa<PHINode>(BBI))
739 return nullptr;
740 }
741
742 // Do not break infinite loops.
743 BasicBlock *DestBB = BI->getSuccessor(0);
744 if (DestBB == BB)
745 return nullptr;
746
747 if (!canMergeBlocks(BB, DestBB))
748 DestBB = nullptr;
749
750 return DestBB;
751}
752
753/// Eliminate blocks that contain only PHI nodes, debug info directives, and an
754/// unconditional branch. Passes before isel (e.g. LSR/loopsimplify) often split
755/// edges in ways that are non-optimal for isel. Start by eliminating these
756/// blocks so we can split them the way we want them.
757bool CodeGenPrepare::eliminateMostlyEmptyBlocks(Function &F) {
758 SmallPtrSet<BasicBlock *, 16> Preheaders;
759 SmallVector<Loop *, 16> LoopList(LI->begin(), LI->end());
760 while (!LoopList.empty()) {
761 Loop *L = LoopList.pop_back_val();
762 llvm::append_range(LoopList, *L);
763 if (BasicBlock *Preheader = L->getLoopPreheader())
764 Preheaders.insert(Preheader);
765 }
766
767 bool MadeChange = false;
768 // Copy blocks into a temporary array to avoid iterator invalidation issues
769 // as we remove them.
770 // Note that this intentionally skips the entry block.
771 SmallVector<WeakTrackingVH, 16> Blocks;
772 for (auto &Block : llvm::drop_begin(F))
773 Blocks.push_back(&Block);
774
775 for (auto &Block : Blocks) {
776 BasicBlock *BB = cast_or_null<BasicBlock>(Block);
777 if (!BB)
778 continue;
779 BasicBlock *DestBB = findDestBlockOfMergeableEmptyBlock(BB);
780 if (!DestBB ||
781 !isMergingEmptyBlockProfitable(BB, DestBB, Preheaders.count(BB)))
782 continue;
783
784 eliminateMostlyEmptyBlock(BB);
785 MadeChange = true;
786 }
787 return MadeChange;
788}
789
790bool CodeGenPrepare::isMergingEmptyBlockProfitable(BasicBlock *BB,
791 BasicBlock *DestBB,
792 bool isPreheader) {
793 // Do not delete loop preheaders if doing so would create a critical edge.
794 // Loop preheaders can be good locations to spill registers. If the
795 // preheader is deleted and we create a critical edge, registers may be
796 // spilled in the loop body instead.
797 if (!DisablePreheaderProtect && isPreheader &&
798 !(BB->getSinglePredecessor() &&
799 BB->getSinglePredecessor()->getSingleSuccessor()))
800 return false;
801
802 // Skip merging if the block's successor is also a successor to any callbr
803 // that leads to this block.
804 // FIXME: Is this really needed? Is this a correctness issue?
805 for (BasicBlock *Pred : predecessors(BB)) {
806 if (auto *CBI = dyn_cast<CallBrInst>((Pred)->getTerminator()))
807 for (unsigned i = 0, e = CBI->getNumSuccessors(); i != e; ++i)
808 if (DestBB == CBI->getSuccessor(i))
809 return false;
810 }
811
812 // Try to skip merging if the unique predecessor of BB is terminated by a
813 // switch or indirect branch instruction, and BB is used as an incoming block
814 // of PHIs in DestBB. In such case, merging BB and DestBB would cause ISel to
815 // add COPY instructions in the predecessor of BB instead of BB (if it is not
816 // merged). Note that the critical edge created by merging such blocks wont be
817 // split in MachineSink because the jump table is not analyzable. By keeping
818 // such empty block (BB), ISel will place COPY instructions in BB, not in the
819 // predecessor of BB.
820 BasicBlock *Pred = BB->getUniquePredecessor();
821 if (!Pred ||
822 !(isa<SwitchInst>(Pred->getTerminator()) ||
823 isa<IndirectBrInst>(Pred->getTerminator())))
824 return true;
825
826 if (BB->getTerminator() != BB->getFirstNonPHIOrDbg())
827 return true;
828
829 // We use a simple cost heuristic which determine skipping merging is
830 // profitable if the cost of skipping merging is less than the cost of
831 // merging : Cost(skipping merging) < Cost(merging BB), where the
832 // Cost(skipping merging) is Freq(BB) * (Cost(Copy) + Cost(Branch)), and
833 // the Cost(merging BB) is Freq(Pred) * Cost(Copy).
834 // Assuming Cost(Copy) == Cost(Branch), we could simplify it to :
835 // Freq(Pred) / Freq(BB) > 2.
836 // Note that if there are multiple empty blocks sharing the same incoming
837 // value for the PHIs in the DestBB, we consider them together. In such
838 // case, Cost(merging BB) will be the sum of their frequencies.
839
840 if (!isa<PHINode>(DestBB->begin()))
841 return true;
842
843 SmallPtrSet<BasicBlock *, 16> SameIncomingValueBBs;
844
845 // Find all other incoming blocks from which incoming values of all PHIs in
846 // DestBB are the same as the ones from BB.
847 for (BasicBlock *DestBBPred : predecessors(DestBB)) {
848 if (DestBBPred == BB)
849 continue;
850
851 if (llvm::all_of(DestBB->phis(), [&](const PHINode &DestPN) {
852 return DestPN.getIncomingValueForBlock(BB) ==
853 DestPN.getIncomingValueForBlock(DestBBPred);
854 }))
855 SameIncomingValueBBs.insert(DestBBPred);
856 }
857
858 // See if all BB's incoming values are same as the value from Pred. In this
859 // case, no reason to skip merging because COPYs are expected to be place in
860 // Pred already.
861 if (SameIncomingValueBBs.count(Pred))
862 return true;
863
864 BlockFrequency PredFreq = BFI->getBlockFreq(Pred);
865 BlockFrequency BBFreq = BFI->getBlockFreq(BB);
866
867 for (auto *SameValueBB : SameIncomingValueBBs)
868 if (SameValueBB->getUniquePredecessor() == Pred &&
869 DestBB == findDestBlockOfMergeableEmptyBlock(SameValueBB))
870 BBFreq += BFI->getBlockFreq(SameValueBB);
871
872 return PredFreq.getFrequency() <=
873 BBFreq.getFrequency() * FreqRatioToSkipMerge;
874}
875
876/// Return true if we can merge BB into DestBB if there is a single
877/// unconditional branch between them, and BB contains no other non-phi
878/// instructions.
879bool CodeGenPrepare::canMergeBlocks(const BasicBlock *BB,
880 const BasicBlock *DestBB) const {
881 // We only want to eliminate blocks whose phi nodes are used by phi nodes in
882 // the successor. If there are more complex condition (e.g. preheaders),
883 // don't mess around with them.
884 for (const PHINode &PN : BB->phis()) {
885 for (const User *U : PN.users()) {
886 const Instruction *UI = cast<Instruction>(U);
887 if (UI->getParent() != DestBB || !isa<PHINode>(UI))
888 return false;
889 // If User is inside DestBB block and it is a PHINode then check
890 // incoming value. If incoming value is not from BB then this is
891 // a complex condition (e.g. preheaders) we want to avoid here.
892 if (UI->getParent() == DestBB) {
893 if (const PHINode *UPN = dyn_cast<PHINode>(UI))
894 for (unsigned I = 0, E = UPN->getNumIncomingValues(); I != E; ++I) {
895 Instruction *Insn = dyn_cast<Instruction>(UPN->getIncomingValue(I));
896 if (Insn && Insn->getParent() == BB &&
897 Insn->getParent() != UPN->getIncomingBlock(I))
898 return false;
899 }
900 }
901 }
902 }
903
904 // If BB and DestBB contain any common predecessors, then the phi nodes in BB
905 // and DestBB may have conflicting incoming values for the block. If so, we
906 // can't merge the block.
907 const PHINode *DestBBPN = dyn_cast<PHINode>(DestBB->begin());
908 if (!DestBBPN) return true; // no conflict.
909
910 // Collect the preds of BB.
911 SmallPtrSet<const BasicBlock*, 16> BBPreds;
912 if (const PHINode *BBPN = dyn_cast<PHINode>(BB->begin())) {
913 // It is faster to get preds from a PHI than with pred_iterator.
914 for (unsigned i = 0, e = BBPN->getNumIncomingValues(); i != e; ++i)
915 BBPreds.insert(BBPN->getIncomingBlock(i));
916 } else {
917 BBPreds.insert(pred_begin(BB), pred_end(BB));
918 }
919
920 // Walk the preds of DestBB.
921 for (unsigned i = 0, e = DestBBPN->getNumIncomingValues(); i != e; ++i) {
922 BasicBlock *Pred = DestBBPN->getIncomingBlock(i);
923 if (BBPreds.count(Pred)) { // Common predecessor?
924 for (const PHINode &PN : DestBB->phis()) {
925 const Value *V1 = PN.getIncomingValueForBlock(Pred);
926 const Value *V2 = PN.getIncomingValueForBlock(BB);
927
928 // If V2 is a phi node in BB, look up what the mapped value will be.
929 if (const PHINode *V2PN = dyn_cast<PHINode>(V2))
930 if (V2PN->getParent() == BB)
931 V2 = V2PN->getIncomingValueForBlock(Pred);
932
933 // If there is a conflict, bail out.
934 if (V1 != V2) return false;
935 }
936 }
937 }
938
939 return true;
940}
941
942/// Eliminate a basic block that has only phi's and an unconditional branch in
943/// it.
944void CodeGenPrepare::eliminateMostlyEmptyBlock(BasicBlock *BB) {
945 BranchInst *BI = cast<BranchInst>(BB->getTerminator());
946 BasicBlock *DestBB = BI->getSuccessor(0);
947
948 LLVM_DEBUG(dbgs() << "MERGING MOSTLY EMPTY BLOCKS - BEFORE:\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "MERGING MOSTLY EMPTY BLOCKS - BEFORE:\n"
<< *BB << *DestBB; } } while (false)
949 << *BB << *DestBB)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "MERGING MOSTLY EMPTY BLOCKS - BEFORE:\n"
<< *BB << *DestBB; } } while (false)
;
950
951 // If the destination block has a single pred, then this is a trivial edge,
952 // just collapse it.
953 if (BasicBlock *SinglePred = DestBB->getSinglePredecessor()) {
954 if (SinglePred != DestBB) {
955 assert(SinglePred == BB &&(static_cast <bool> (SinglePred == BB && "Single predecessor not the same as predecessor"
) ? void (0) : __assert_fail ("SinglePred == BB && \"Single predecessor not the same as predecessor\""
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 956, __extension__ __PRETTY_FUNCTION__
))
956 "Single predecessor not the same as predecessor")(static_cast <bool> (SinglePred == BB && "Single predecessor not the same as predecessor"
) ? void (0) : __assert_fail ("SinglePred == BB && \"Single predecessor not the same as predecessor\""
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 956, __extension__ __PRETTY_FUNCTION__
))
;
957 // Merge DestBB into SinglePred/BB and delete it.
958 MergeBlockIntoPredecessor(DestBB);
959 // Note: BB(=SinglePred) will not be deleted on this path.
960 // DestBB(=its single successor) is the one that was deleted.
961 LLVM_DEBUG(dbgs() << "AFTER:\n" << *SinglePred << "\n\n\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "AFTER:\n" << *SinglePred
<< "\n\n\n"; } } while (false)
;
962 return;
963 }
964 }
965
966 // Otherwise, we have multiple predecessors of BB. Update the PHIs in DestBB
967 // to handle the new incoming edges it is about to have.
968 for (PHINode &PN : DestBB->phis()) {
969 // Remove the incoming value for BB, and remember it.
970 Value *InVal = PN.removeIncomingValue(BB, false);
971
972 // Two options: either the InVal is a phi node defined in BB or it is some
973 // value that dominates BB.
974 PHINode *InValPhi = dyn_cast<PHINode>(InVal);
975 if (InValPhi && InValPhi->getParent() == BB) {
976 // Add all of the input values of the input PHI as inputs of this phi.
977 for (unsigned i = 0, e = InValPhi->getNumIncomingValues(); i != e; ++i)
978 PN.addIncoming(InValPhi->getIncomingValue(i),
979 InValPhi->getIncomingBlock(i));
980 } else {
981 // Otherwise, add one instance of the dominating value for each edge that
982 // we will be adding.
983 if (PHINode *BBPN = dyn_cast<PHINode>(BB->begin())) {
984 for (unsigned i = 0, e = BBPN->getNumIncomingValues(); i != e; ++i)
985 PN.addIncoming(InVal, BBPN->getIncomingBlock(i));
986 } else {
987 for (BasicBlock *Pred : predecessors(BB))
988 PN.addIncoming(InVal, Pred);
989 }
990 }
991 }
992
993 // The PHIs are now updated, change everything that refers to BB to use
994 // DestBB and remove BB.
995 BB->replaceAllUsesWith(DestBB);
996 BB->eraseFromParent();
997 ++NumBlocksElim;
998
999 LLVM_DEBUG(dbgs() << "AFTER:\n" << *DestBB << "\n\n\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "AFTER:\n" << *DestBB
<< "\n\n\n"; } } while (false)
;
1000}
1001
1002// Computes a map of base pointer relocation instructions to corresponding
1003// derived pointer relocation instructions given a vector of all relocate calls
1004static void computeBaseDerivedRelocateMap(
1005 const SmallVectorImpl<GCRelocateInst *> &AllRelocateCalls,
1006 DenseMap<GCRelocateInst *, SmallVector<GCRelocateInst *, 2>>
1007 &RelocateInstMap) {
1008 // Collect information in two maps: one primarily for locating the base object
1009 // while filling the second map; the second map is the final structure holding
1010 // a mapping between Base and corresponding Derived relocate calls
1011 DenseMap<std::pair<unsigned, unsigned>, GCRelocateInst *> RelocateIdxMap;
1012 for (auto *ThisRelocate : AllRelocateCalls) {
1013 auto K = std::make_pair(ThisRelocate->getBasePtrIndex(),
1014 ThisRelocate->getDerivedPtrIndex());
1015 RelocateIdxMap.insert(std::make_pair(K, ThisRelocate));
1016 }
1017 for (auto &Item : RelocateIdxMap) {
1018 std::pair<unsigned, unsigned> Key = Item.first;
1019 if (Key.first == Key.second)
1020 // Base relocation: nothing to insert
1021 continue;
1022
1023 GCRelocateInst *I = Item.second;
1024 auto BaseKey = std::make_pair(Key.first, Key.first);
1025
1026 // We're iterating over RelocateIdxMap so we cannot modify it.
1027 auto MaybeBase = RelocateIdxMap.find(BaseKey);
1028 if (MaybeBase == RelocateIdxMap.end())
1029 // TODO: We might want to insert a new base object relocate and gep off
1030 // that, if there are enough derived object relocates.
1031 continue;
1032
1033 RelocateInstMap[MaybeBase->second].push_back(I);
1034 }
1035}
1036
1037// Accepts a GEP and extracts the operands into a vector provided they're all
1038// small integer constants
1039static bool getGEPSmallConstantIntOffsetV(GetElementPtrInst *GEP,
1040 SmallVectorImpl<Value *> &OffsetV) {
1041 for (unsigned i = 1; i < GEP->getNumOperands(); i++) {
1042 // Only accept small constant integer operands
1043 auto *Op = dyn_cast<ConstantInt>(GEP->getOperand(i));
1044 if (!Op || Op->getZExtValue() > 20)
1045 return false;
1046 }
1047
1048 for (unsigned i = 1; i < GEP->getNumOperands(); i++)
1049 OffsetV.push_back(GEP->getOperand(i));
1050 return true;
1051}
1052
1053// Takes a RelocatedBase (base pointer relocation instruction) and Targets to
1054// replace, computes a replacement, and affects it.
1055static bool
1056simplifyRelocatesOffABase(GCRelocateInst *RelocatedBase,
1057 const SmallVectorImpl<GCRelocateInst *> &Targets) {
1058 bool MadeChange = false;
1059 // We must ensure the relocation of derived pointer is defined after
1060 // relocation of base pointer. If we find a relocation corresponding to base
1061 // defined earlier than relocation of base then we move relocation of base
1062 // right before found relocation. We consider only relocation in the same
1063 // basic block as relocation of base. Relocations from other basic block will
1064 // be skipped by optimization and we do not care about them.
1065 for (auto R = RelocatedBase->getParent()->getFirstInsertionPt();
1066 &*R != RelocatedBase; ++R)
1067 if (auto *RI = dyn_cast<GCRelocateInst>(R))
1068 if (RI->getStatepoint() == RelocatedBase->getStatepoint())
1069 if (RI->getBasePtrIndex() == RelocatedBase->getBasePtrIndex()) {
1070 RelocatedBase->moveBefore(RI);
1071 break;
1072 }
1073
1074 for (GCRelocateInst *ToReplace : Targets) {
1075 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\""
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 1076, __extension__ __PRETTY_FUNCTION__
))
1076 "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\""
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 1076, __extension__ __PRETTY_FUNCTION__
))
;
1077 if (ToReplace->getBasePtrIndex() == ToReplace->getDerivedPtrIndex()) {
1078 // A duplicate relocate call. TODO: coalesce duplicates.
1079 continue;
1080 }
1081
1082 if (RelocatedBase->getParent() != ToReplace->getParent()) {
1083 // Base and derived relocates are in different basic blocks.
1084 // In this case transform is only valid when base dominates derived
1085 // relocate. However it would be too expensive to check dominance
1086 // for each such relocate, so we skip the whole transformation.
1087 continue;
1088 }
1089
1090 Value *Base = ToReplace->getBasePtr();
1091 auto *Derived = dyn_cast<GetElementPtrInst>(ToReplace->getDerivedPtr());
1092 if (!Derived || Derived->getPointerOperand() != Base)
1093 continue;
1094
1095 SmallVector<Value *, 2> OffsetV;
1096 if (!getGEPSmallConstantIntOffsetV(Derived, OffsetV))
1097 continue;
1098
1099 // Create a Builder and replace the target callsite with a gep
1100 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\""
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 1101, __extension__ __PRETTY_FUNCTION__
))
1101 "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\""
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 1101, __extension__ __PRETTY_FUNCTION__
))
;
1102
1103 // Insert after RelocatedBase
1104 IRBuilder<> Builder(RelocatedBase->getNextNode());
1105 Builder.SetCurrentDebugLocation(ToReplace->getDebugLoc());
1106
1107 // If gc_relocate does not match the actual type, cast it to the right type.
1108 // In theory, there must be a bitcast after gc_relocate if the type does not
1109 // match, and we should reuse it to get the derived pointer. But it could be
1110 // cases like this:
1111 // bb1:
1112 // ...
1113 // %g1 = call coldcc i8 addrspace(1)* @llvm.experimental.gc.relocate.p1i8(...)
1114 // br label %merge
1115 //
1116 // bb2:
1117 // ...
1118 // %g2 = call coldcc i8 addrspace(1)* @llvm.experimental.gc.relocate.p1i8(...)
1119 // br label %merge
1120 //
1121 // merge:
1122 // %p1 = phi i8 addrspace(1)* [ %g1, %bb1 ], [ %g2, %bb2 ]
1123 // %cast = bitcast i8 addrspace(1)* %p1 in to i32 addrspace(1)*
1124 //
1125 // In this case, we can not find the bitcast any more. So we insert a new bitcast
1126 // no matter there is already one or not. In this way, we can handle all cases, and
1127 // the extra bitcast should be optimized away in later passes.
1128 Value *ActualRelocatedBase = RelocatedBase;
1129 if (RelocatedBase->getType() != Base->getType()) {
1130 ActualRelocatedBase =
1131 Builder.CreateBitCast(RelocatedBase, Base->getType());
1132 }
1133 Value *Replacement = Builder.CreateGEP(
1134 Derived->getSourceElementType(), ActualRelocatedBase, makeArrayRef(OffsetV));
1135 Replacement->takeName(ToReplace);
1136 // If the newly generated derived pointer's type does not match the original derived
1137 // pointer's type, cast the new derived pointer to match it. Same reasoning as above.
1138 Value *ActualReplacement = Replacement;
1139 if (Replacement->getType() != ToReplace->getType()) {
1140 ActualReplacement =
1141 Builder.CreateBitCast(Replacement, ToReplace->getType());
1142 }
1143 ToReplace->replaceAllUsesWith(ActualReplacement);
1144 ToReplace->eraseFromParent();
1145
1146 MadeChange = true;
1147 }
1148 return MadeChange;
1149}
1150
1151// Turns this:
1152//
1153// %base = ...
1154// %ptr = gep %base + 15
1155// %tok = statepoint (%fun, i32 0, i32 0, i32 0, %base, %ptr)
1156// %base' = relocate(%tok, i32 4, i32 4)
1157// %ptr' = relocate(%tok, i32 4, i32 5)
1158// %val = load %ptr'
1159//
1160// into this:
1161//
1162// %base = ...
1163// %ptr = gep %base + 15
1164// %tok = statepoint (%fun, i32 0, i32 0, i32 0, %base, %ptr)
1165// %base' = gc.relocate(%tok, i32 4, i32 4)
1166// %ptr' = gep %base' + 15
1167// %val = load %ptr'
1168bool CodeGenPrepare::simplifyOffsetableRelocate(GCStatepointInst &I) {
1169 bool MadeChange = false;
1170 SmallVector<GCRelocateInst *, 2> AllRelocateCalls;
1171 for (auto *U : I.users())
1172 if (GCRelocateInst *Relocate = dyn_cast<GCRelocateInst>(U))
1173 // Collect all the relocate calls associated with a statepoint
1174 AllRelocateCalls.push_back(Relocate);
1175
1176 // We need at least one base pointer relocation + one derived pointer
1177 // relocation to mangle
1178 if (AllRelocateCalls.size() < 2)
1179 return false;
1180
1181 // RelocateInstMap is a mapping from the base relocate instruction to the
1182 // corresponding derived relocate instructions
1183 DenseMap<GCRelocateInst *, SmallVector<GCRelocateInst *, 2>> RelocateInstMap;
1184 computeBaseDerivedRelocateMap(AllRelocateCalls, RelocateInstMap);
1185 if (RelocateInstMap.empty())
1186 return false;
1187
1188 for (auto &Item : RelocateInstMap)
1189 // Item.first is the RelocatedBase to offset against
1190 // Item.second is the vector of Targets to replace
1191 MadeChange = simplifyRelocatesOffABase(Item.first, Item.second);
1192 return MadeChange;
1193}
1194
1195/// Sink the specified cast instruction into its user blocks.
1196static bool SinkCast(CastInst *CI) {
1197 BasicBlock *DefBB = CI->getParent();
1198
1199 /// InsertedCasts - Only insert a cast in each block once.
1200 DenseMap<BasicBlock*, CastInst*> InsertedCasts;
1201
1202 bool MadeChange = false;
1203 for (Value::user_iterator UI = CI->user_begin(), E = CI->user_end();
1204 UI != E; ) {
1205 Use &TheUse = UI.getUse();
1206 Instruction *User = cast<Instruction>(*UI);
1207
1208 // Figure out which BB this cast is used in. For PHI's this is the
1209 // appropriate predecessor block.
1210 BasicBlock *UserBB = User->getParent();
1211 if (PHINode *PN = dyn_cast<PHINode>(User)) {
1212 UserBB = PN->getIncomingBlock(TheUse);
1213 }
1214
1215 // Preincrement use iterator so we don't invalidate it.
1216 ++UI;
1217
1218 // The first insertion point of a block containing an EH pad is after the
1219 // pad. If the pad is the user, we cannot sink the cast past the pad.
1220 if (User->isEHPad())
1221 continue;
1222
1223 // If the block selected to receive the cast is an EH pad that does not
1224 // allow non-PHI instructions before the terminator, we can't sink the
1225 // cast.
1226 if (UserBB->getTerminator()->isEHPad())
1227 continue;
1228
1229 // If this user is in the same block as the cast, don't change the cast.
1230 if (UserBB == DefBB) continue;
1231
1232 // If we have already inserted a cast into this block, use it.
1233 CastInst *&InsertedCast = InsertedCasts[UserBB];
1234
1235 if (!InsertedCast) {
1236 BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
1237 assert(InsertPt != UserBB->end())(static_cast <bool> (InsertPt != UserBB->end()) ? void
(0) : __assert_fail ("InsertPt != UserBB->end()", "llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 1237, __extension__ __PRETTY_FUNCTION__))
;
1238 InsertedCast = CastInst::Create(CI->getOpcode(), CI->getOperand(0),
1239 CI->getType(), "", &*InsertPt);
1240 InsertedCast->setDebugLoc(CI->getDebugLoc());
1241 }
1242
1243 // Replace a use of the cast with a use of the new cast.
1244 TheUse = InsertedCast;
1245 MadeChange = true;
1246 ++NumCastUses;
1247 }
1248
1249 // If we removed all uses, nuke the cast.
1250 if (CI->use_empty()) {
1251 salvageDebugInfo(*CI);
1252 CI->eraseFromParent();
1253 MadeChange = true;
1254 }
1255
1256 return MadeChange;
1257}
1258
1259/// If the specified cast instruction is a noop copy (e.g. it's casting from
1260/// one pointer type to another, i32->i8 on PPC), sink it into user blocks to
1261/// reduce the number of virtual registers that must be created and coalesced.
1262///
1263/// Return true if any changes are made.
1264static bool OptimizeNoopCopyExpression(CastInst *CI, const TargetLowering &TLI,
1265 const DataLayout &DL) {
1266 // Sink only "cheap" (or nop) address-space casts. This is a weaker condition
1267 // than sinking only nop casts, but is helpful on some platforms.
1268 if (auto *ASC = dyn_cast<AddrSpaceCastInst>(CI)) {
1269 if (!TLI.isFreeAddrSpaceCast(ASC->getSrcAddressSpace(),
1270 ASC->getDestAddressSpace()))
1271 return false;
1272 }
1273
1274 // If this is a noop copy,
1275 EVT SrcVT = TLI.getValueType(DL, CI->getOperand(0)->getType());
1276 EVT DstVT = TLI.getValueType(DL, CI->getType());
1277
1278 // This is an fp<->int conversion?
1279 if (SrcVT.isInteger() != DstVT.isInteger())
1280 return false;
1281
1282 // If this is an extension, it will be a zero or sign extension, which
1283 // isn't a noop.
1284 if (SrcVT.bitsLT(DstVT)) return false;
1285
1286 // If these values will be promoted, find out what they will be promoted
1287 // to. This helps us consider truncates on PPC as noop copies when they
1288 // are.
1289 if (TLI.getTypeAction(CI->getContext(), SrcVT) ==
1290 TargetLowering::TypePromoteInteger)
1291 SrcVT = TLI.getTypeToTransformTo(CI->getContext(), SrcVT);
1292 if (TLI.getTypeAction(CI->getContext(), DstVT) ==
1293 TargetLowering::TypePromoteInteger)
1294 DstVT = TLI.getTypeToTransformTo(CI->getContext(), DstVT);
1295
1296 // If, after promotion, these are the same types, this is a noop copy.
1297 if (SrcVT != DstVT)
1298 return false;
1299
1300 return SinkCast(CI);
1301}
1302
1303// Match a simple increment by constant operation. Note that if a sub is
1304// matched, the step is negated (as if the step had been canonicalized to
1305// an add, even though we leave the instruction alone.)
1306bool matchIncrement(const Instruction* IVInc, Instruction *&LHS,
1307 Constant *&Step) {
1308 if (match(IVInc, m_Add(m_Instruction(LHS), m_Constant(Step))) ||
1309 match(IVInc, m_ExtractValue<0>(m_Intrinsic<Intrinsic::uadd_with_overflow>(
1310 m_Instruction(LHS), m_Constant(Step)))))
1311 return true;
1312 if (match(IVInc, m_Sub(m_Instruction(LHS), m_Constant(Step))) ||
1313 match(IVInc, m_ExtractValue<0>(m_Intrinsic<Intrinsic::usub_with_overflow>(
1314 m_Instruction(LHS), m_Constant(Step))))) {
1315 Step = ConstantExpr::getNeg(Step);
1316 return true;
1317 }
1318 return false;
1319}
1320
1321/// If given \p PN is an inductive variable with value IVInc coming from the
1322/// backedge, and on each iteration it gets increased by Step, return pair
1323/// <IVInc, Step>. Otherwise, return None.
1324static Optional<std::pair<Instruction *, Constant *> >
1325getIVIncrement(const PHINode *PN, const LoopInfo *LI) {
1326 const Loop *L = LI->getLoopFor(PN->getParent());
1327 if (!L || L->getHeader() != PN->getParent() || !L->getLoopLatch())
1328 return None;
1329 auto *IVInc =
1330 dyn_cast<Instruction>(PN->getIncomingValueForBlock(L->getLoopLatch()));
1331 if (!IVInc || LI->getLoopFor(IVInc->getParent()) != L)
1332 return None;
1333 Instruction *LHS = nullptr;
1334 Constant *Step = nullptr;
1335 if (matchIncrement(IVInc, LHS, Step) && LHS == PN)
1336 return std::make_pair(IVInc, Step);
1337 return None;
1338}
1339
1340static bool isIVIncrement(const Value *V, const LoopInfo *LI) {
1341 auto *I = dyn_cast<Instruction>(V);
1342 if (!I)
1343 return false;
1344 Instruction *LHS = nullptr;
1345 Constant *Step = nullptr;
1346 if (!matchIncrement(I, LHS, Step))
1347 return false;
1348 if (auto *PN = dyn_cast<PHINode>(LHS))
1349 if (auto IVInc = getIVIncrement(PN, LI))
1350 return IVInc->first == I;
1351 return false;
1352}
1353
1354bool CodeGenPrepare::replaceMathCmpWithIntrinsic(BinaryOperator *BO,
1355 Value *Arg0, Value *Arg1,
1356 CmpInst *Cmp,
1357 Intrinsic::ID IID) {
1358 auto IsReplacableIVIncrement = [this, &Cmp](BinaryOperator *BO) {
1359 if (!isIVIncrement(BO, LI))
1360 return false;
1361 const Loop *L = LI->getLoopFor(BO->getParent());
1362 assert(L && "L should not be null after isIVIncrement()")(static_cast <bool> (L && "L should not be null after isIVIncrement()"
) ? void (0) : __assert_fail ("L && \"L should not be null after isIVIncrement()\""
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 1362, __extension__ __PRETTY_FUNCTION__
))
;
1363 // Do not risk on moving increment into a child loop.
1364 if (LI->getLoopFor(Cmp->getParent()) != L)
1365 return false;
1366
1367 // Finally, we need to ensure that the insert point will dominate all
1368 // existing uses of the increment.
1369
1370 auto &DT = getDT(*BO->getParent()->getParent());
1371 if (DT.dominates(Cmp->getParent(), BO->getParent()))
1372 // If we're moving up the dom tree, all uses are trivially dominated.
1373 // (This is the common case for code produced by LSR.)
1374 return true;
1375
1376 // Otherwise, special case the single use in the phi recurrence.
1377 return BO->hasOneUse() && DT.dominates(Cmp->getParent(), L->getLoopLatch());
1378 };
1379 if (BO->getParent() != Cmp->getParent() && !IsReplacableIVIncrement(BO)) {
1380 // We used to use a dominator tree here to allow multi-block optimization.
1381 // But that was problematic because:
1382 // 1. It could cause a perf regression by hoisting the math op into the
1383 // critical path.
1384 // 2. It could cause a perf regression by creating a value that was live
1385 // across multiple blocks and increasing register pressure.
1386 // 3. Use of a dominator tree could cause large compile-time regression.
1387 // This is because we recompute the DT on every change in the main CGP
1388 // run-loop. The recomputing is probably unnecessary in many cases, so if
1389 // that was fixed, using a DT here would be ok.
1390 //
1391 // There is one important particular case we still want to handle: if BO is
1392 // the IV increment. Important properties that make it profitable:
1393 // - We can speculate IV increment anywhere in the loop (as long as the
1394 // indvar Phi is its only user);
1395 // - Upon computing Cmp, we effectively compute something equivalent to the
1396 // IV increment (despite it loops differently in the IR). So moving it up
1397 // to the cmp point does not really increase register pressure.
1398 return false;
1399 }
1400
1401 // We allow matching the canonical IR (add X, C) back to (usubo X, -C).
1402 if (BO->getOpcode() == Instruction::Add &&
1403 IID == Intrinsic::usub_with_overflow) {
1404 assert(isa<Constant>(Arg1) && "Unexpected input for usubo")(static_cast <bool> (isa<Constant>(Arg1) &&
"Unexpected input for usubo") ? void (0) : __assert_fail ("isa<Constant>(Arg1) && \"Unexpected input for usubo\""
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 1404, __extension__ __PRETTY_FUNCTION__
))
;
1405 Arg1 = ConstantExpr::getNeg(cast<Constant>(Arg1));
1406 }
1407
1408 // Insert at the first instruction of the pair.
1409 Instruction *InsertPt = nullptr;
1410 for (Instruction &Iter : *Cmp->getParent()) {
1411 // If BO is an XOR, it is not guaranteed that it comes after both inputs to
1412 // the overflow intrinsic are defined.
1413 if ((BO->getOpcode() != Instruction::Xor && &Iter == BO) || &Iter == Cmp) {
1414 InsertPt = &Iter;
1415 break;
1416 }
1417 }
1418 assert(InsertPt != nullptr && "Parent block did not contain cmp or binop")(static_cast <bool> (InsertPt != nullptr && "Parent block did not contain cmp or binop"
) ? void (0) : __assert_fail ("InsertPt != nullptr && \"Parent block did not contain cmp or binop\""
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 1418, __extension__ __PRETTY_FUNCTION__
))
;
1419
1420 IRBuilder<> Builder(InsertPt);
1421 Value *MathOV = Builder.CreateBinaryIntrinsic(IID, Arg0, Arg1);
1422 if (BO->getOpcode() != Instruction::Xor) {
1423 Value *Math = Builder.CreateExtractValue(MathOV, 0, "math");
1424 BO->replaceAllUsesWith(Math);
1425 } else
1426 assert(BO->hasOneUse() &&(static_cast <bool> (BO->hasOneUse() && "Patterns with XOr should use the BO only in the compare"
) ? void (0) : __assert_fail ("BO->hasOneUse() && \"Patterns with XOr should use the BO only in the compare\""
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 1427, __extension__ __PRETTY_FUNCTION__
))
1427 "Patterns with XOr should use the BO only in the compare")(static_cast <bool> (BO->hasOneUse() && "Patterns with XOr should use the BO only in the compare"
) ? void (0) : __assert_fail ("BO->hasOneUse() && \"Patterns with XOr should use the BO only in the compare\""
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 1427, __extension__ __PRETTY_FUNCTION__
))
;
1428 Value *OV = Builder.CreateExtractValue(MathOV, 1, "ov");
1429 Cmp->replaceAllUsesWith(OV);
1430 Cmp->eraseFromParent();
1431 BO->eraseFromParent();
1432 return true;
1433}
1434
1435/// Match special-case patterns that check for unsigned add overflow.
1436static bool matchUAddWithOverflowConstantEdgeCases(CmpInst *Cmp,
1437 BinaryOperator *&Add) {
1438 // Add = add A, 1; Cmp = icmp eq A,-1 (overflow if A is max val)
1439 // Add = add A,-1; Cmp = icmp ne A, 0 (overflow if A is non-zero)
1440 Value *A = Cmp->getOperand(0), *B = Cmp->getOperand(1);
1441
1442 // We are not expecting non-canonical/degenerate code. Just bail out.
1443 if (isa<Constant>(A))
1444 return false;
1445
1446 ICmpInst::Predicate Pred = Cmp->getPredicate();
1447 if (Pred == ICmpInst::ICMP_EQ && match(B, m_AllOnes()))
1448 B = ConstantInt::get(B->getType(), 1);
1449 else if (Pred == ICmpInst::ICMP_NE && match(B, m_ZeroInt()))
1450 B = ConstantInt::get(B->getType(), -1);
1451 else
1452 return false;
1453
1454 // Check the users of the variable operand of the compare looking for an add
1455 // with the adjusted constant.
1456 for (User *U : A->users()) {
1457 if (match(U, m_Add(m_Specific(A), m_Specific(B)))) {
1458 Add = cast<BinaryOperator>(U);
1459 return true;
1460 }
1461 }
1462 return false;
1463}
1464
1465/// Try to combine the compare into a call to the llvm.uadd.with.overflow
1466/// intrinsic. Return true if any changes were made.
1467bool CodeGenPrepare::combineToUAddWithOverflow(CmpInst *Cmp,
1468 bool &ModifiedDT) {
1469 Value *A, *B;
1470 BinaryOperator *Add;
1471 if (!match(Cmp, m_UAddWithOverflow(m_Value(A), m_Value(B), m_BinOp(Add)))) {
1472 if (!matchUAddWithOverflowConstantEdgeCases(Cmp, Add))
1473 return false;
1474 // Set A and B in case we match matchUAddWithOverflowConstantEdgeCases.
1475 A = Add->getOperand(0);
1476 B = Add->getOperand(1);
1477 }
1478
1479 if (!TLI->shouldFormOverflowOp(ISD::UADDO,
1480 TLI->getValueType(*DL, Add->getType()),
1481 Add->hasNUsesOrMore(2)))
1482 return false;
1483
1484 // We don't want to move around uses of condition values this late, so we
1485 // check if it is legal to create the call to the intrinsic in the basic
1486 // block containing the icmp.
1487 if (Add->getParent() != Cmp->getParent() && !Add->hasOneUse())
1488 return false;
1489
1490 if (!replaceMathCmpWithIntrinsic(Add, A, B, Cmp,
1491 Intrinsic::uadd_with_overflow))
1492 return false;
1493
1494 // Reset callers - do not crash by iterating over a dead instruction.
1495 ModifiedDT = true;
1496 return true;
1497}
1498
1499bool CodeGenPrepare::combineToUSubWithOverflow(CmpInst *Cmp,
1500 bool &ModifiedDT) {
1501 // We are not expecting non-canonical/degenerate code. Just bail out.
1502 Value *A = Cmp->getOperand(0), *B = Cmp->getOperand(1);
1503 if (isa<Constant>(A) && isa<Constant>(B))
1504 return false;
1505
1506 // Convert (A u> B) to (A u< B) to simplify pattern matching.
1507 ICmpInst::Predicate Pred = Cmp->getPredicate();
1508 if (Pred == ICmpInst::ICMP_UGT) {
1509 std::swap(A, B);
1510 Pred = ICmpInst::ICMP_ULT;
1511 }
1512 // Convert special-case: (A == 0) is the same as (A u< 1).
1513 if (Pred == ICmpInst::ICMP_EQ && match(B, m_ZeroInt())) {
1514 B = ConstantInt::get(B->getType(), 1);
1515 Pred = ICmpInst::ICMP_ULT;
1516 }
1517 // Convert special-case: (A != 0) is the same as (0 u< A).
1518 if (Pred == ICmpInst::ICMP_NE && match(B, m_ZeroInt())) {
1519 std::swap(A, B);
1520 Pred = ICmpInst::ICMP_ULT;
1521 }
1522 if (Pred != ICmpInst::ICMP_ULT)
1523 return false;
1524
1525 // Walk the users of a variable operand of a compare looking for a subtract or
1526 // add with that same operand. Also match the 2nd operand of the compare to
1527 // the add/sub, but that may be a negated constant operand of an add.
1528 Value *CmpVariableOperand = isa<Constant>(A) ? B : A;
1529 BinaryOperator *Sub = nullptr;
1530 for (User *U : CmpVariableOperand->users()) {
1531 // A - B, A u< B --> usubo(A, B)
1532 if (match(U, m_Sub(m_Specific(A), m_Specific(B)))) {
1533 Sub = cast<BinaryOperator>(U);
1534 break;
1535 }
1536
1537 // A + (-C), A u< C (canonicalized form of (sub A, C))
1538 const APInt *CmpC, *AddC;
1539 if (match(U, m_Add(m_Specific(A), m_APInt(AddC))) &&
1540 match(B, m_APInt(CmpC)) && *AddC == -(*CmpC)) {
1541 Sub = cast<BinaryOperator>(U);
1542 break;
1543 }
1544 }
1545 if (!Sub)
1546 return false;
1547
1548 if (!TLI->shouldFormOverflowOp(ISD::USUBO,
1549 TLI->getValueType(*DL, Sub->getType()),
1550 Sub->hasNUsesOrMore(2)))
1551 return false;
1552
1553 if (!replaceMathCmpWithIntrinsic(Sub, Sub->getOperand(0), Sub->getOperand(1),
1554 Cmp, Intrinsic::usub_with_overflow))
1555 return false;
1556
1557 // Reset callers - do not crash by iterating over a dead instruction.
1558 ModifiedDT = true;
1559 return true;
1560}
1561
1562/// Sink the given CmpInst into user blocks to reduce the number of virtual
1563/// registers that must be created and coalesced. This is a clear win except on
1564/// targets with multiple condition code registers (PowerPC), where it might
1565/// lose; some adjustment may be wanted there.
1566///
1567/// Return true if any changes are made.
1568static bool sinkCmpExpression(CmpInst *Cmp, const TargetLowering &TLI) {
1569 if (TLI.hasMultipleConditionRegisters())
1570 return false;
1571
1572 // Avoid sinking soft-FP comparisons, since this can move them into a loop.
1573 if (TLI.useSoftFloat() && isa<FCmpInst>(Cmp))
1574 return false;
1575
1576 // Only insert a cmp in each block once.
1577 DenseMap<BasicBlock*, CmpInst*> InsertedCmps;
1578
1579 bool MadeChange = false;
1580 for (Value::user_iterator UI = Cmp->user_begin(), E = Cmp->user_end();
1581 UI != E; ) {
1582 Use &TheUse = UI.getUse();
1583 Instruction *User = cast<Instruction>(*UI);
1584
1585 // Preincrement use iterator so we don't invalidate it.
1586 ++UI;
1587
1588 // Don't bother for PHI nodes.
1589 if (isa<PHINode>(User))
1590 continue;
1591
1592 // Figure out which BB this cmp is used in.
1593 BasicBlock *UserBB = User->getParent();
1594 BasicBlock *DefBB = Cmp->getParent();
1595
1596 // If this user is in the same block as the cmp, don't change the cmp.
1597 if (UserBB == DefBB) continue;
1598
1599 // If we have already inserted a cmp into this block, use it.
1600 CmpInst *&InsertedCmp = InsertedCmps[UserBB];
1601
1602 if (!InsertedCmp) {
1603 BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
1604 assert(InsertPt != UserBB->end())(static_cast <bool> (InsertPt != UserBB->end()) ? void
(0) : __assert_fail ("InsertPt != UserBB->end()", "llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 1604, __extension__ __PRETTY_FUNCTION__))
;
1605 InsertedCmp =
1606 CmpInst::Create(Cmp->getOpcode(), Cmp->getPredicate(),
1607 Cmp->getOperand(0), Cmp->getOperand(1), "",
1608 &*InsertPt);
1609 // Propagate the debug info.
1610 InsertedCmp->setDebugLoc(Cmp->getDebugLoc());
1611 }
1612
1613 // Replace a use of the cmp with a use of the new cmp.
1614 TheUse = InsertedCmp;
1615 MadeChange = true;
1616 ++NumCmpUses;
1617 }
1618
1619 // If we removed all uses, nuke the cmp.
1620 if (Cmp->use_empty()) {
1621 Cmp->eraseFromParent();
1622 MadeChange = true;
1623 }
1624
1625 return MadeChange;
1626}
1627
1628/// For pattern like:
1629///
1630/// DomCond = icmp sgt/slt CmpOp0, CmpOp1 (might not be in DomBB)
1631/// ...
1632/// DomBB:
1633/// ...
1634/// br DomCond, TrueBB, CmpBB
1635/// CmpBB: (with DomBB being the single predecessor)
1636/// ...
1637/// Cmp = icmp eq CmpOp0, CmpOp1
1638/// ...
1639///
1640/// It would use two comparison on targets that lowering of icmp sgt/slt is
1641/// different from lowering of icmp eq (PowerPC). This function try to convert
1642/// 'Cmp = icmp eq CmpOp0, CmpOp1' to ' Cmp = icmp slt/sgt CmpOp0, CmpOp1'.
1643/// After that, DomCond and Cmp can use the same comparison so reduce one
1644/// comparison.
1645///
1646/// Return true if any changes are made.
1647static bool foldICmpWithDominatingICmp(CmpInst *Cmp,
1648 const TargetLowering &TLI) {
1649 if (!EnableICMP_EQToICMP_ST && TLI.isEqualityCmpFoldedWithSignedCmp())
1650 return false;
1651
1652 ICmpInst::Predicate Pred = Cmp->getPredicate();
1653 if (Pred != ICmpInst::ICMP_EQ)
1654 return false;
1655
1656 // If icmp eq has users other than BranchInst and SelectInst, converting it to
1657 // icmp slt/sgt would introduce more redundant LLVM IR.
1658 for (User *U : Cmp->users()) {
1659 if (isa<BranchInst>(U))
1660 continue;
1661 if (isa<SelectInst>(U) && cast<SelectInst>(U)->getCondition() == Cmp)
1662 continue;
1663 return false;
1664 }
1665
1666 // This is a cheap/incomplete check for dominance - just match a single
1667 // predecessor with a conditional branch.
1668 BasicBlock *CmpBB = Cmp->getParent();
1669 BasicBlock *DomBB = CmpBB->getSinglePredecessor();
1670 if (!DomBB)
1671 return false;
1672
1673 // We want to ensure that the only way control gets to the comparison of
1674 // interest is that a less/greater than comparison on the same operands is
1675 // false.
1676 Value *DomCond;
1677 BasicBlock *TrueBB, *FalseBB;
1678 if (!match(DomBB->getTerminator(), m_Br(m_Value(DomCond), TrueBB, FalseBB)))
1679 return false;
1680 if (CmpBB != FalseBB)
1681 return false;
1682
1683 Value *CmpOp0 = Cmp->getOperand(0), *CmpOp1 = Cmp->getOperand(1);
1684 ICmpInst::Predicate DomPred;
1685 if (!match(DomCond, m_ICmp(DomPred, m_Specific(CmpOp0), m_Specific(CmpOp1))))
1686 return false;
1687 if (DomPred != ICmpInst::ICMP_SGT && DomPred != ICmpInst::ICMP_SLT)
1688 return false;
1689
1690 // Convert the equality comparison to the opposite of the dominating
1691 // comparison and swap the direction for all branch/select users.
1692 // We have conceptually converted:
1693 // Res = (a < b) ? <LT_RES> : (a == b) ? <EQ_RES> : <GT_RES>;
1694 // to
1695 // Res = (a < b) ? <LT_RES> : (a > b) ? <GT_RES> : <EQ_RES>;
1696 // And similarly for branches.
1697 for (User *U : Cmp->users()) {
1698 if (auto *BI = dyn_cast<BranchInst>(U)) {
1699 assert(BI->isConditional() && "Must be conditional")(static_cast <bool> (BI->isConditional() && "Must be conditional"
) ? void (0) : __assert_fail ("BI->isConditional() && \"Must be conditional\""
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 1699, __extension__ __PRETTY_FUNCTION__
))
;
1700 BI->swapSuccessors();
1701 continue;
1702 }
1703 if (auto *SI = dyn_cast<SelectInst>(U)) {
1704 // Swap operands
1705 SI->swapValues();
1706 SI->swapProfMetadata();
1707 continue;
1708 }
1709 llvm_unreachable("Must be a branch or a select")::llvm::llvm_unreachable_internal("Must be a branch or a select"
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 1709)
;
1710 }
1711 Cmp->setPredicate(CmpInst::getSwappedPredicate(DomPred));
1712 return true;
1713}
1714
1715bool CodeGenPrepare::optimizeCmp(CmpInst *Cmp, bool &ModifiedDT) {
1716 if (sinkCmpExpression(Cmp, *TLI))
1717 return true;
1718
1719 if (combineToUAddWithOverflow(Cmp, ModifiedDT))
1720 return true;
1721
1722 if (combineToUSubWithOverflow(Cmp, ModifiedDT))
1723 return true;
1724
1725 if (foldICmpWithDominatingICmp(Cmp, *TLI))
1726 return true;
1727
1728 return false;
1729}
1730
1731/// Duplicate and sink the given 'and' instruction into user blocks where it is
1732/// used in a compare to allow isel to generate better code for targets where
1733/// this operation can be combined.
1734///
1735/// Return true if any changes are made.
1736static bool sinkAndCmp0Expression(Instruction *AndI,
1737 const TargetLowering &TLI,
1738 SetOfInstrs &InsertedInsts) {
1739 // Double-check that we're not trying to optimize an instruction that was
1740 // already optimized by some other part of this pass.
1741 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\""
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 1742, __extension__ __PRETTY_FUNCTION__
))
1742 "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\""
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 1742, __extension__ __PRETTY_FUNCTION__
))
;
1743 (void) InsertedInsts;
1744
1745 // Nothing to do for single use in same basic block.
1746 if (AndI->hasOneUse() &&
1747 AndI->getParent() == cast<Instruction>(*AndI->user_begin())->getParent())
1748 return false;
1749
1750 // Try to avoid cases where sinking/duplicating is likely to increase register
1751 // pressure.
1752 if (!isa<ConstantInt>(AndI->getOperand(0)) &&
1753 !isa<ConstantInt>(AndI->getOperand(1)) &&
1754 AndI->getOperand(0)->hasOneUse() && AndI->getOperand(1)->hasOneUse())
1755 return false;
1756
1757 for (auto *U : AndI->users()) {
1758 Instruction *User = cast<Instruction>(U);
1759
1760 // Only sink 'and' feeding icmp with 0.
1761 if (!isa<ICmpInst>(User))
1762 return false;
1763
1764 auto *CmpC = dyn_cast<ConstantInt>(User->getOperand(1));
1765 if (!CmpC || !CmpC->isZero())
1766 return false;
1767 }
1768
1769 if (!TLI.isMaskAndCmp0FoldingBeneficial(*AndI))
1770 return false;
1771
1772 LLVM_DEBUG(dbgs() << "found 'and' feeding only icmp 0;\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "found 'and' feeding only icmp 0;\n"
; } } while (false)
;
1773 LLVM_DEBUG(AndI->getParent()->dump())do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { AndI->getParent()->dump(); } } while
(false)
;
1774
1775 // Push the 'and' into the same block as the icmp 0. There should only be
1776 // one (icmp (and, 0)) in each block, since CSE/GVN should have removed any
1777 // others, so we don't need to keep track of which BBs we insert into.
1778 for (Value::user_iterator UI = AndI->user_begin(), E = AndI->user_end();
1779 UI != E; ) {
1780 Use &TheUse = UI.getUse();
1781 Instruction *User = cast<Instruction>(*UI);
1782
1783 // Preincrement use iterator so we don't invalidate it.
1784 ++UI;
1785
1786 LLVM_DEBUG(dbgs() << "sinking 'and' use: " << *User << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "sinking 'and' use: " <<
*User << "\n"; } } while (false)
;
1787
1788 // Keep the 'and' in the same place if the use is already in the same block.
1789 Instruction *InsertPt =
1790 User->getParent() == AndI->getParent() ? AndI : User;
1791 Instruction *InsertedAnd =
1792 BinaryOperator::Create(Instruction::And, AndI->getOperand(0),
1793 AndI->getOperand(1), "", InsertPt);
1794 // Propagate the debug info.
1795 InsertedAnd->setDebugLoc(AndI->getDebugLoc());
1796
1797 // Replace a use of the 'and' with a use of the new 'and'.
1798 TheUse = InsertedAnd;
1799 ++NumAndUses;
1800 LLVM_DEBUG(User->getParent()->dump())do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { User->getParent()->dump(); } } while
(false)
;
1801 }
1802
1803 // We removed all uses, nuke the and.
1804 AndI->eraseFromParent();
1805 return true;
1806}
1807
1808/// Check if the candidates could be combined with a shift instruction, which
1809/// includes:
1810/// 1. Truncate instruction
1811/// 2. And instruction and the imm is a mask of the low bits:
1812/// imm & (imm+1) == 0
1813static bool isExtractBitsCandidateUse(Instruction *User) {
1814 if (!isa<TruncInst>(User)) {
1815 if (User->getOpcode() != Instruction::And ||
1816 !isa<ConstantInt>(User->getOperand(1)))
1817 return false;
1818
1819 const APInt &Cimm = cast<ConstantInt>(User->getOperand(1))->getValue();
1820
1821 if ((Cimm & (Cimm + 1)).getBoolValue())
1822 return false;
1823 }
1824 return true;
1825}
1826
1827/// Sink both shift and truncate instruction to the use of truncate's BB.
1828static bool
1829SinkShiftAndTruncate(BinaryOperator *ShiftI, Instruction *User, ConstantInt *CI,
1830 DenseMap<BasicBlock *, BinaryOperator *> &InsertedShifts,
1831 const TargetLowering &TLI, const DataLayout &DL) {
1832 BasicBlock *UserBB = User->getParent();
1833 DenseMap<BasicBlock *, CastInst *> InsertedTruncs;
1834 auto *TruncI = cast<TruncInst>(User);
1835 bool MadeChange = false;
1836
1837 for (Value::user_iterator TruncUI = TruncI->user_begin(),
1838 TruncE = TruncI->user_end();
1839 TruncUI != TruncE;) {
1840
1841 Use &TruncTheUse = TruncUI.getUse();
1842 Instruction *TruncUser = cast<Instruction>(*TruncUI);
1843 // Preincrement use iterator so we don't invalidate it.
1844
1845 ++TruncUI;
1846
1847 int ISDOpcode = TLI.InstructionOpcodeToISD(TruncUser->getOpcode());
1848 if (!ISDOpcode)
1849 continue;
1850
1851 // If the use is actually a legal node, there will not be an
1852 // implicit truncate.
1853 // FIXME: always querying the result type is just an
1854 // approximation; some nodes' legality is determined by the
1855 // operand or other means. There's no good way to find out though.
1856 if (TLI.isOperationLegalOrCustom(
1857 ISDOpcode, TLI.getValueType(DL, TruncUser->getType(), true)))
1858 continue;
1859
1860 // Don't bother for PHI nodes.
1861 if (isa<PHINode>(TruncUser))
1862 continue;
1863
1864 BasicBlock *TruncUserBB = TruncUser->getParent();
1865
1866 if (UserBB == TruncUserBB)
1867 continue;
1868
1869 BinaryOperator *&InsertedShift = InsertedShifts[TruncUserBB];
1870 CastInst *&InsertedTrunc = InsertedTruncs[TruncUserBB];
1871
1872 if (!InsertedShift && !InsertedTrunc) {
1873 BasicBlock::iterator InsertPt = TruncUserBB->getFirstInsertionPt();
1874 assert(InsertPt != TruncUserBB->end())(static_cast <bool> (InsertPt != TruncUserBB->end())
? void (0) : __assert_fail ("InsertPt != TruncUserBB->end()"
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 1874, __extension__ __PRETTY_FUNCTION__
))
;
1875 // Sink the shift
1876 if (ShiftI->getOpcode() == Instruction::AShr)
1877 InsertedShift = BinaryOperator::CreateAShr(ShiftI->getOperand(0), CI,
1878 "", &*InsertPt);
1879 else
1880 InsertedShift = BinaryOperator::CreateLShr(ShiftI->getOperand(0), CI,
1881 "", &*InsertPt);
1882 InsertedShift->setDebugLoc(ShiftI->getDebugLoc());
1883
1884 // Sink the trunc
1885 BasicBlock::iterator TruncInsertPt = TruncUserBB->getFirstInsertionPt();
1886 TruncInsertPt++;
1887 assert(TruncInsertPt != TruncUserBB->end())(static_cast <bool> (TruncInsertPt != TruncUserBB->end
()) ? void (0) : __assert_fail ("TruncInsertPt != TruncUserBB->end()"
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 1887, __extension__ __PRETTY_FUNCTION__
))
;
1888
1889 InsertedTrunc = CastInst::Create(TruncI->getOpcode(), InsertedShift,
1890 TruncI->getType(), "", &*TruncInsertPt);
1891 InsertedTrunc->setDebugLoc(TruncI->getDebugLoc());
1892
1893 MadeChange = true;
1894
1895 TruncTheUse = InsertedTrunc;
1896 }
1897 }
1898 return MadeChange;
1899}
1900
1901/// Sink the shift *right* instruction into user blocks if the uses could
1902/// potentially be combined with this shift instruction and generate BitExtract
1903/// instruction. It will only be applied if the architecture supports BitExtract
1904/// instruction. Here is an example:
1905/// BB1:
1906/// %x.extract.shift = lshr i64 %arg1, 32
1907/// BB2:
1908/// %x.extract.trunc = trunc i64 %x.extract.shift to i16
1909/// ==>
1910///
1911/// BB2:
1912/// %x.extract.shift.1 = lshr i64 %arg1, 32
1913/// %x.extract.trunc = trunc i64 %x.extract.shift.1 to i16
1914///
1915/// CodeGen will recognize the pattern in BB2 and generate BitExtract
1916/// instruction.
1917/// Return true if any changes are made.
1918static bool OptimizeExtractBits(BinaryOperator *ShiftI, ConstantInt *CI,
1919 const TargetLowering &TLI,
1920 const DataLayout &DL) {
1921 BasicBlock *DefBB = ShiftI->getParent();
1922
1923 /// Only insert instructions in each block once.
1924 DenseMap<BasicBlock *, BinaryOperator *> InsertedShifts;
1925
1926 bool shiftIsLegal = TLI.isTypeLegal(TLI.getValueType(DL, ShiftI->getType()));
1927
1928 bool MadeChange = false;
1929 for (Value::user_iterator UI = ShiftI->user_begin(), E = ShiftI->user_end();
1930 UI != E;) {
1931 Use &TheUse = UI.getUse();
1932 Instruction *User = cast<Instruction>(*UI);
1933 // Preincrement use iterator so we don't invalidate it.
1934 ++UI;
1935
1936 // Don't bother for PHI nodes.
1937 if (isa<PHINode>(User))
1938 continue;
1939
1940 if (!isExtractBitsCandidateUse(User))
1941 continue;
1942
1943 BasicBlock *UserBB = User->getParent();
1944
1945 if (UserBB == DefBB) {
1946 // If the shift and truncate instruction are in the same BB. The use of
1947 // the truncate(TruncUse) may still introduce another truncate if not
1948 // legal. In this case, we would like to sink both shift and truncate
1949 // instruction to the BB of TruncUse.
1950 // for example:
1951 // BB1:
1952 // i64 shift.result = lshr i64 opnd, imm
1953 // trunc.result = trunc shift.result to i16
1954 //
1955 // BB2:
1956 // ----> We will have an implicit truncate here if the architecture does
1957 // not have i16 compare.
1958 // cmp i16 trunc.result, opnd2
1959 //
1960 if (isa<TruncInst>(User) && shiftIsLegal
1961 // If the type of the truncate is legal, no truncate will be
1962 // introduced in other basic blocks.
1963 &&
1964 (!TLI.isTypeLegal(TLI.getValueType(DL, User->getType()))))
1965 MadeChange =
1966 SinkShiftAndTruncate(ShiftI, User, CI, InsertedShifts, TLI, DL);
1967
1968 continue;
1969 }
1970 // If we have already inserted a shift into this block, use it.
1971 BinaryOperator *&InsertedShift = InsertedShifts[UserBB];
1972
1973 if (!InsertedShift) {
1974 BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
1975 assert(InsertPt != UserBB->end())(static_cast <bool> (InsertPt != UserBB->end()) ? void
(0) : __assert_fail ("InsertPt != UserBB->end()", "llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 1975, __extension__ __PRETTY_FUNCTION__))
;
1976
1977 if (ShiftI->getOpcode() == Instruction::AShr)
1978 InsertedShift = BinaryOperator::CreateAShr(ShiftI->getOperand(0), CI,
1979 "", &*InsertPt);
1980 else
1981 InsertedShift = BinaryOperator::CreateLShr(ShiftI->getOperand(0), CI,
1982 "", &*InsertPt);
1983 InsertedShift->setDebugLoc(ShiftI->getDebugLoc());
1984
1985 MadeChange = true;
1986 }
1987
1988 // Replace a use of the shift with a use of the new shift.
1989 TheUse = InsertedShift;
1990 }
1991
1992 // If we removed all uses, or there are none, nuke the shift.
1993 if (ShiftI->use_empty()) {
1994 salvageDebugInfo(*ShiftI);
1995 ShiftI->eraseFromParent();
1996 MadeChange = true;
1997 }
1998
1999 return MadeChange;
2000}
2001
2002/// If counting leading or trailing zeros is an expensive operation and a zero
2003/// input is defined, add a check for zero to avoid calling the intrinsic.
2004///
2005/// We want to transform:
2006/// %z = call i64 @llvm.cttz.i64(i64 %A, i1 false)
2007///
2008/// into:
2009/// entry:
2010/// %cmpz = icmp eq i64 %A, 0
2011/// br i1 %cmpz, label %cond.end, label %cond.false
2012/// cond.false:
2013/// %z = call i64 @llvm.cttz.i64(i64 %A, i1 true)
2014/// br label %cond.end
2015/// cond.end:
2016/// %ctz = phi i64 [ 64, %entry ], [ %z, %cond.false ]
2017///
2018/// If the transform is performed, return true and set ModifiedDT to true.
2019static bool despeculateCountZeros(IntrinsicInst *CountZeros,
2020 const TargetLowering *TLI,
2021 const DataLayout *DL,
2022 bool &ModifiedDT) {
2023 // If a zero input is undefined, it doesn't make sense to despeculate that.
2024 if (match(CountZeros->getOperand(1), m_One()))
2025 return false;
2026
2027 // If it's cheap to speculate, there's nothing to do.
2028 auto IntrinsicID = CountZeros->getIntrinsicID();
2029 if ((IntrinsicID == Intrinsic::cttz && TLI->isCheapToSpeculateCttz()) ||
2030 (IntrinsicID == Intrinsic::ctlz && TLI->isCheapToSpeculateCtlz()))
2031 return false;
2032
2033 // Only handle legal scalar cases. Anything else requires too much work.
2034 Type *Ty = CountZeros->getType();
2035 unsigned SizeInBits = Ty->getScalarSizeInBits();
2036 if (Ty->isVectorTy() || SizeInBits > DL->getLargestLegalIntTypeSizeInBits())
2037 return false;
2038
2039 // Bail if the value is never zero.
2040 if (llvm::isKnownNonZero(CountZeros->getOperand(0), *DL))
2041 return false;
2042
2043 // The intrinsic will be sunk behind a compare against zero and branch.
2044 BasicBlock *StartBlock = CountZeros->getParent();
2045 BasicBlock *CallBlock = StartBlock->splitBasicBlock(CountZeros, "cond.false");
2046
2047 // Create another block after the count zero intrinsic. A PHI will be added
2048 // in this block to select the result of the intrinsic or the bit-width
2049 // constant if the input to the intrinsic is zero.
2050 BasicBlock::iterator SplitPt = ++(BasicBlock::iterator(CountZeros));
2051 BasicBlock *EndBlock = CallBlock->splitBasicBlock(SplitPt, "cond.end");
2052
2053 // Set up a builder to create a compare, conditional branch, and PHI.
2054 IRBuilder<> Builder(CountZeros->getContext());
2055 Builder.SetInsertPoint(StartBlock->getTerminator());
2056 Builder.SetCurrentDebugLocation(CountZeros->getDebugLoc());
2057
2058 // Replace the unconditional branch that was created by the first split with
2059 // a compare against zero and a conditional branch.
2060 Value *Zero = Constant::getNullValue(Ty);
2061 Value *Cmp = Builder.CreateICmpEQ(CountZeros->getOperand(0), Zero, "cmpz");
2062 Builder.CreateCondBr(Cmp, EndBlock, CallBlock);
2063 StartBlock->getTerminator()->eraseFromParent();
2064
2065 // Create a PHI in the end block to select either the output of the intrinsic
2066 // or the bit width of the operand.
2067 Builder.SetInsertPoint(&EndBlock->front());
2068 PHINode *PN = Builder.CreatePHI(Ty, 2, "ctz");
2069 CountZeros->replaceAllUsesWith(PN);
2070 Value *BitWidth = Builder.getInt(APInt(SizeInBits, SizeInBits));
2071 PN->addIncoming(BitWidth, StartBlock);
2072 PN->addIncoming(CountZeros, CallBlock);
2073
2074 // We are explicitly handling the zero case, so we can set the intrinsic's
2075 // undefined zero argument to 'true'. This will also prevent reprocessing the
2076 // intrinsic; we only despeculate when a zero input is defined.
2077 CountZeros->setArgOperand(1, Builder.getTrue());
2078 ModifiedDT = true;
2079 return true;
2080}
2081
2082bool CodeGenPrepare::optimizeCallInst(CallInst *CI, bool &ModifiedDT) {
2083 BasicBlock *BB = CI->getParent();
2084
2085 // Lower inline assembly if we can.
2086 // If we found an inline asm expession, and if the target knows how to
2087 // lower it to normal LLVM code, do so now.
2088 if (CI->isInlineAsm()) {
2089 if (TLI->ExpandInlineAsm(CI)) {
2090 // Avoid invalidating the iterator.
2091 CurInstIterator = BB->begin();
2092 // Avoid processing instructions out of order, which could cause
2093 // reuse before a value is defined.
2094 SunkAddrs.clear();
2095 return true;
2096 }
2097 // Sink address computing for memory operands into the block.
2098 if (optimizeInlineAsmInst(CI))
2099 return true;
2100 }
2101
2102 // Align the pointer arguments to this call if the target thinks it's a good
2103 // idea
2104 unsigned MinSize, PrefAlign;
2105 if (TLI->shouldAlignPointerArgs(CI, MinSize, PrefAlign)) {
2106 for (auto &Arg : CI->args()) {
2107 // We want to align both objects whose address is used directly and
2108 // objects whose address is used in casts and GEPs, though it only makes
2109 // sense for GEPs if the offset is a multiple of the desired alignment and
2110 // if size - offset meets the size threshold.
2111 if (!Arg->getType()->isPointerTy())
2112 continue;
2113 APInt Offset(DL->getIndexSizeInBits(
2114 cast<PointerType>(Arg->getType())->getAddressSpace()),
2115 0);
2116 Value *Val = Arg->stripAndAccumulateInBoundsConstantOffsets(*DL, Offset);
2117 uint64_t Offset2 = Offset.getLimitedValue();
2118 if ((Offset2 & (PrefAlign-1)) != 0)
2119 continue;
2120 AllocaInst *AI;
2121 if ((AI = dyn_cast<AllocaInst>(Val)) && AI->getAlignment() < PrefAlign &&
2122 DL->getTypeAllocSize(AI->getAllocatedType()) >= MinSize + Offset2)
2123 AI->setAlignment(Align(PrefAlign));
2124 // Global variables can only be aligned if they are defined in this
2125 // object (i.e. they are uniquely initialized in this object), and
2126 // over-aligning global variables that have an explicit section is
2127 // forbidden.
2128 GlobalVariable *GV;
2129 if ((GV = dyn_cast<GlobalVariable>(Val)) && GV->canIncreaseAlignment() &&
2130 GV->getPointerAlignment(*DL) < PrefAlign &&
2131 DL->getTypeAllocSize(GV->getValueType()) >=
2132 MinSize + Offset2)
2133 GV->setAlignment(MaybeAlign(PrefAlign));
2134 }
2135 // If this is a memcpy (or similar) then we may be able to improve the
2136 // alignment
2137 if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(CI)) {
2138 Align DestAlign = getKnownAlignment(MI->getDest(), *DL);
2139 MaybeAlign MIDestAlign = MI->getDestAlign();
2140 if (!MIDestAlign || DestAlign > *MIDestAlign)
2141 MI->setDestAlignment(DestAlign);
2142 if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(MI)) {
2143 MaybeAlign MTISrcAlign = MTI->getSourceAlign();
2144 Align SrcAlign = getKnownAlignment(MTI->getSource(), *DL);
2145 if (!MTISrcAlign || SrcAlign > *MTISrcAlign)
2146 MTI->setSourceAlignment(SrcAlign);
2147 }
2148 }
2149 }
2150
2151 // If we have a cold call site, try to sink addressing computation into the
2152 // cold block. This interacts with our handling for loads and stores to
2153 // ensure that we can fold all uses of a potential addressing computation
2154 // into their uses. TODO: generalize this to work over profiling data
2155 if (CI->hasFnAttr(Attribute::Cold) &&
2156 !OptSize && !llvm::shouldOptimizeForSize(BB, PSI, BFI.get()))
2157 for (auto &Arg : CI->args()) {
2158 if (!Arg->getType()->isPointerTy())
2159 continue;
2160 unsigned AS = Arg->getType()->getPointerAddressSpace();
2161 return optimizeMemoryInst(CI, Arg, Arg->getType(), AS);
2162 }
2163
2164 IntrinsicInst *II = dyn_cast<IntrinsicInst>(CI);
2165 if (II) {
2166 switch (II->getIntrinsicID()) {
2167 default: break;
2168 case Intrinsic::assume:
2169 llvm_unreachable("llvm.assume should have been removed already")::llvm::llvm_unreachable_internal("llvm.assume should have been removed already"
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 2169)
;
2170 case Intrinsic::experimental_widenable_condition: {
2171 // Give up on future widening oppurtunties so that we can fold away dead
2172 // paths and merge blocks before going into block-local instruction
2173 // selection.
2174 if (II->use_empty()) {
2175 II->eraseFromParent();
2176 return true;
2177 }
2178 Constant *RetVal = ConstantInt::getTrue(II->getContext());
2179 resetIteratorIfInvalidatedWhileCalling(BB, [&]() {
2180 replaceAndRecursivelySimplify(CI, RetVal, TLInfo, nullptr);
2181 });
2182 return true;
2183 }
2184 case Intrinsic::objectsize:
2185 llvm_unreachable("llvm.objectsize.* should have been lowered already")::llvm::llvm_unreachable_internal("llvm.objectsize.* should have been lowered already"
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 2185)
;
2186 case Intrinsic::is_constant:
2187 llvm_unreachable("llvm.is.constant.* should have been lowered already")::llvm::llvm_unreachable_internal("llvm.is.constant.* should have been lowered already"
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 2187)
;
2188 case Intrinsic::aarch64_stlxr:
2189 case Intrinsic::aarch64_stxr: {
2190 ZExtInst *ExtVal = dyn_cast<ZExtInst>(CI->getArgOperand(0));
2191 if (!ExtVal || !ExtVal->hasOneUse() ||
2192 ExtVal->getParent() == CI->getParent())
2193 return false;
2194 // Sink a zext feeding stlxr/stxr before it, so it can be folded into it.
2195 ExtVal->moveBefore(CI);
2196 // Mark this instruction as "inserted by CGP", so that other
2197 // optimizations don't touch it.
2198 InsertedInsts.insert(ExtVal);
2199 return true;
2200 }
2201
2202 case Intrinsic::launder_invariant_group:
2203 case Intrinsic::strip_invariant_group: {
2204 Value *ArgVal = II->getArgOperand(0);
2205 auto it = LargeOffsetGEPMap.find(II);
2206 if (it != LargeOffsetGEPMap.end()) {
2207 // Merge entries in LargeOffsetGEPMap to reflect the RAUW.
2208 // Make sure not to have to deal with iterator invalidation
2209 // after possibly adding ArgVal to LargeOffsetGEPMap.
2210 auto GEPs = std::move(it->second);
2211 LargeOffsetGEPMap[ArgVal].append(GEPs.begin(), GEPs.end());
2212 LargeOffsetGEPMap.erase(II);
2213 }
2214
2215 II->replaceAllUsesWith(ArgVal);
2216 II->eraseFromParent();
2217 return true;
2218 }
2219 case Intrinsic::cttz:
2220 case Intrinsic::ctlz:
2221 // If counting zeros is expensive, try to avoid it.
2222 return despeculateCountZeros(II, TLI, DL, ModifiedDT);
2223 case Intrinsic::fshl:
2224 case Intrinsic::fshr:
2225 return optimizeFunnelShift(II);
2226 case Intrinsic::dbg_value:
2227 return fixupDbgValue(II);
2228 case Intrinsic::vscale: {
2229 // If datalayout has no special restrictions on vector data layout,
2230 // replace `llvm.vscale` by an equivalent constant expression
2231 // to benefit from cheap constant propagation.
2232 Type *ScalableVectorTy =
2233 VectorType::get(Type::getInt8Ty(II->getContext()), 1, true);
2234 if (DL->getTypeAllocSize(ScalableVectorTy).getKnownMinSize() == 8) {
2235 auto *Null = Constant::getNullValue(ScalableVectorTy->getPointerTo());
2236 auto *One = ConstantInt::getSigned(II->getType(), 1);
2237 auto *CGep =
2238 ConstantExpr::getGetElementPtr(ScalableVectorTy, Null, One);
2239 II->replaceAllUsesWith(ConstantExpr::getPtrToInt(CGep, II->getType()));
2240 II->eraseFromParent();
2241 return true;
2242 }
2243 break;
2244 }
2245 case Intrinsic::masked_gather:
2246 return optimizeGatherScatterInst(II, II->getArgOperand(0));
2247 case Intrinsic::masked_scatter:
2248 return optimizeGatherScatterInst(II, II->getArgOperand(1));
2249 }
2250
2251 SmallVector<Value *, 2> PtrOps;
2252 Type *AccessTy;
2253 if (TLI->getAddrModeArguments(II, PtrOps, AccessTy))
2254 while (!PtrOps.empty()) {
2255 Value *PtrVal = PtrOps.pop_back_val();
2256 unsigned AS = PtrVal->getType()->getPointerAddressSpace();
2257 if (optimizeMemoryInst(II, PtrVal, AccessTy, AS))
2258 return true;
2259 }
2260 }
2261
2262 // From here on out we're working with named functions.
2263 if (!CI->getCalledFunction()) return false;
2264
2265 // Lower all default uses of _chk calls. This is very similar
2266 // to what InstCombineCalls does, but here we are only lowering calls
2267 // to fortified library functions (e.g. __memcpy_chk) that have the default
2268 // "don't know" as the objectsize. Anything else should be left alone.
2269 FortifiedLibCallSimplifier Simplifier(TLInfo, true);
2270 IRBuilder<> Builder(CI);
2271 if (Value *V = Simplifier.optimizeCall(CI, Builder)) {
2272 CI->replaceAllUsesWith(V);
2273 CI->eraseFromParent();
2274 return true;
2275 }
2276
2277 return false;
2278}
2279
2280/// Look for opportunities to duplicate return instructions to the predecessor
2281/// to enable tail call optimizations. The case it is currently looking for is:
2282/// @code
2283/// bb0:
2284/// %tmp0 = tail call i32 @f0()
2285/// br label %return
2286/// bb1:
2287/// %tmp1 = tail call i32 @f1()
2288/// br label %return
2289/// bb2:
2290/// %tmp2 = tail call i32 @f2()
2291/// br label %return
2292/// return:
2293/// %retval = phi i32 [ %tmp0, %bb0 ], [ %tmp1, %bb1 ], [ %tmp2, %bb2 ]
2294/// ret i32 %retval
2295/// @endcode
2296///
2297/// =>
2298///
2299/// @code
2300/// bb0:
2301/// %tmp0 = tail call i32 @f0()
2302/// ret i32 %tmp0
2303/// bb1:
2304/// %tmp1 = tail call i32 @f1()
2305/// ret i32 %tmp1
2306/// bb2:
2307/// %tmp2 = tail call i32 @f2()
2308/// ret i32 %tmp2
2309/// @endcode
2310bool CodeGenPrepare::dupRetToEnableTailCallOpts(BasicBlock *BB, bool &ModifiedDT) {
2311 ReturnInst *RetI = dyn_cast<ReturnInst>(BB->getTerminator());
2312 if (!RetI)
2313 return false;
2314
2315 PHINode *PN = nullptr;
2316 ExtractValueInst *EVI = nullptr;
2317 BitCastInst *BCI = nullptr;
2318 Value *V = RetI->getReturnValue();
2319 if (V) {
2320 BCI = dyn_cast<BitCastInst>(V);
2321 if (BCI)
2322 V = BCI->getOperand(0);
2323
2324 EVI = dyn_cast<ExtractValueInst>(V);
2325 if (EVI) {
2326 V = EVI->getOperand(0);
2327 if (!llvm::all_of(EVI->indices(), [](unsigned idx) { return idx == 0; }))
2328 return false;
2329 }
2330
2331 PN = dyn_cast<PHINode>(V);
2332 if (!PN)
2333 return false;
2334 }
2335
2336 if (PN && PN->getParent() != BB)
2337 return false;
2338
2339 auto isLifetimeEndOrBitCastFor = [](const Instruction *Inst) {
2340 const BitCastInst *BC = dyn_cast<BitCastInst>(Inst);
2341 if (BC && BC->hasOneUse())
2342 Inst = BC->user_back();
2343
2344 if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst))
2345 return II->getIntrinsicID() == Intrinsic::lifetime_end;
2346 return false;
2347 };
2348
2349 // Make sure there are no instructions between the first instruction
2350 // and return.
2351 const Instruction *BI = BB->getFirstNonPHI();
2352 // Skip over debug and the bitcast.
2353 while (isa<DbgInfoIntrinsic>(BI) || BI == BCI || BI == EVI ||
2354 isa<PseudoProbeInst>(BI) || isLifetimeEndOrBitCastFor(BI))
2355 BI = BI->getNextNode();
2356 if (BI != RetI)
2357 return false;
2358
2359 /// Only dup the ReturnInst if the CallInst is likely to be emitted as a tail
2360 /// call.
2361 const Function *F = BB->getParent();
2362 SmallVector<BasicBlock*, 4> TailCallBBs;
2363 if (PN) {
2364 for (unsigned I = 0, E = PN->getNumIncomingValues(); I != E; ++I) {
2365 // Look through bitcasts.
2366 Value *IncomingVal = PN->getIncomingValue(I)->stripPointerCasts();
2367 CallInst *CI = dyn_cast<CallInst>(IncomingVal);
2368 BasicBlock *PredBB = PN->getIncomingBlock(I);
2369 // Make sure the phi value is indeed produced by the tail call.
2370 if (CI && CI->hasOneUse() && CI->getParent() == PredBB &&
2371 TLI->mayBeEmittedAsTailCall(CI) &&
2372 attributesPermitTailCall(F, CI, RetI, *TLI))
2373 TailCallBBs.push_back(PredBB);
2374 }
2375 } else {
2376 SmallPtrSet<BasicBlock*, 4> VisitedBBs;
2377 for (BasicBlock *Pred : predecessors(BB)) {
2378 if (!VisitedBBs.insert(Pred).second)
2379 continue;
2380 if (Instruction *I = Pred->rbegin()->getPrevNonDebugInstruction(true)) {
2381 CallInst *CI = dyn_cast<CallInst>(I);
2382 if (CI && CI->use_empty() && TLI->mayBeEmittedAsTailCall(CI) &&
2383 attributesPermitTailCall(F, CI, RetI, *TLI))
2384 TailCallBBs.push_back(Pred);
2385 }
2386 }
2387 }
2388
2389 bool Changed = false;
2390 for (auto const &TailCallBB : TailCallBBs) {
2391 // Make sure the call instruction is followed by an unconditional branch to
2392 // the return block.
2393 BranchInst *BI = dyn_cast<BranchInst>(TailCallBB->getTerminator());
2394 if (!BI || !BI->isUnconditional() || BI->getSuccessor(0) != BB)
2395 continue;
2396
2397 // Duplicate the return into TailCallBB.
2398 (void)FoldReturnIntoUncondBranch(RetI, BB, TailCallBB);
2399 assert(!VerifyBFIUpdates ||(static_cast <bool> (!VerifyBFIUpdates || BFI->getBlockFreq
(BB) >= BFI->getBlockFreq(TailCallBB)) ? void (0) : __assert_fail
("!VerifyBFIUpdates || BFI->getBlockFreq(BB) >= BFI->getBlockFreq(TailCallBB)"
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 2400, __extension__ __PRETTY_FUNCTION__
))
2400 BFI->getBlockFreq(BB) >= BFI->getBlockFreq(TailCallBB))(static_cast <bool> (!VerifyBFIUpdates || BFI->getBlockFreq
(BB) >= BFI->getBlockFreq(TailCallBB)) ? void (0) : __assert_fail
("!VerifyBFIUpdates || BFI->getBlockFreq(BB) >= BFI->getBlockFreq(TailCallBB)"
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 2400, __extension__ __PRETTY_FUNCTION__
))
;
2401 BFI->setBlockFreq(
2402 BB,
2403 (BFI->getBlockFreq(BB) - BFI->getBlockFreq(TailCallBB)).getFrequency());
2404 ModifiedDT = Changed = true;
2405 ++NumRetsDup;
2406 }
2407
2408 // If we eliminated all predecessors of the block, delete the block now.
2409 if (Changed && !BB->hasAddressTaken() && pred_empty(BB))
2410 BB->eraseFromParent();
2411
2412 return Changed;
2413}
2414
2415//===----------------------------------------------------------------------===//
2416// Memory Optimization
2417//===----------------------------------------------------------------------===//
2418
2419namespace {
2420
2421/// This is an extended version of TargetLowering::AddrMode
2422/// which holds actual Value*'s for register values.
2423struct ExtAddrMode : public TargetLowering::AddrMode {
2424 Value *BaseReg = nullptr;
2425 Value *ScaledReg = nullptr;
2426 Value *OriginalValue = nullptr;
2427 bool InBounds = true;
2428
2429 enum FieldName {
2430 NoField = 0x00,
2431 BaseRegField = 0x01,
2432 BaseGVField = 0x02,
2433 BaseOffsField = 0x04,
2434 ScaledRegField = 0x08,
2435 ScaleField = 0x10,
2436 MultipleFields = 0xff
2437 };
2438
2439
2440 ExtAddrMode() = default;
2441
2442 void print(raw_ostream &OS) const;
2443 void dump() const;
2444
2445 FieldName compare(const ExtAddrMode &other) {
2446 // First check that the types are the same on each field, as differing types
2447 // is something we can't cope with later on.
2448 if (BaseReg && other.BaseReg &&
2449 BaseReg->getType() != other.BaseReg->getType())
2450 return MultipleFields;
2451 if (BaseGV && other.BaseGV &&
2452 BaseGV->getType() != other.BaseGV->getType())
2453 return MultipleFields;
2454 if (ScaledReg && other.ScaledReg &&
2455 ScaledReg->getType() != other.ScaledReg->getType())
2456 return MultipleFields;
2457
2458 // Conservatively reject 'inbounds' mismatches.
2459 if (InBounds != other.InBounds)
2460 return MultipleFields;
2461
2462 // Check each field to see if it differs.
2463 unsigned Result = NoField;
2464 if (BaseReg != other.BaseReg)
2465 Result |= BaseRegField;
2466 if (BaseGV != other.BaseGV)
2467 Result |= BaseGVField;
2468 if (BaseOffs != other.BaseOffs)
2469 Result |= BaseOffsField;
2470 if (ScaledReg != other.ScaledReg)
2471 Result |= ScaledRegField;
2472 // Don't count 0 as being a different scale, because that actually means
2473 // unscaled (which will already be counted by having no ScaledReg).
2474 if (Scale && other.Scale && Scale != other.Scale)
2475 Result |= ScaleField;
2476
2477 if (countPopulation(Result) > 1)
2478 return MultipleFields;
2479 else
2480 return static_cast<FieldName>(Result);
2481 }
2482
2483 // An AddrMode is trivial if it involves no calculation i.e. it is just a base
2484 // with no offset.
2485 bool isTrivial() {
2486 // An AddrMode is (BaseGV + BaseReg + BaseOffs + ScaleReg * Scale) so it is
2487 // trivial if at most one of these terms is nonzero, except that BaseGV and
2488 // BaseReg both being zero actually means a null pointer value, which we
2489 // consider to be 'non-zero' here.
2490 return !BaseOffs && !Scale && !(BaseGV && BaseReg);
2491 }
2492
2493 Value *GetFieldAsValue(FieldName Field, Type *IntPtrTy) {
2494 switch (Field) {
2495 default:
2496 return nullptr;
2497 case BaseRegField:
2498 return BaseReg;
2499 case BaseGVField:
2500 return BaseGV;
2501 case ScaledRegField:
2502 return ScaledReg;
2503 case BaseOffsField:
2504 return ConstantInt::get(IntPtrTy, BaseOffs);
2505 }
2506 }
2507
2508 void SetCombinedField(FieldName Field, Value *V,
2509 const SmallVectorImpl<ExtAddrMode> &AddrModes) {
2510 switch (Field) {
2511 default:
2512 llvm_unreachable("Unhandled fields are expected to be rejected earlier")::llvm::llvm_unreachable_internal("Unhandled fields are expected to be rejected earlier"
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 2512)
;
2513 break;
2514 case ExtAddrMode::BaseRegField:
2515 BaseReg = V;
2516 break;
2517 case ExtAddrMode::BaseGVField:
2518 // A combined BaseGV is an Instruction, not a GlobalValue, so it goes
2519 // in the BaseReg field.
2520 assert(BaseReg == nullptr)(static_cast <bool> (BaseReg == nullptr) ? void (0) : __assert_fail
("BaseReg == nullptr", "llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 2520, __extension__ __PRETTY_FUNCTION__))
;
2521 BaseReg = V;
2522 BaseGV = nullptr;
2523 break;
2524 case ExtAddrMode::ScaledRegField:
2525 ScaledReg = V;
2526 // If we have a mix of scaled and unscaled addrmodes then we want scale
2527 // to be the scale and not zero.
2528 if (!Scale)
2529 for (const ExtAddrMode &AM : AddrModes)
2530 if (AM.Scale) {
2531 Scale = AM.Scale;
2532 break;
2533 }
2534 break;
2535 case ExtAddrMode::BaseOffsField:
2536 // The offset is no longer a constant, so it goes in ScaledReg with a
2537 // scale of 1.
2538 assert(ScaledReg == nullptr)(static_cast <bool> (ScaledReg == nullptr) ? void (0) :
__assert_fail ("ScaledReg == nullptr", "llvm/lib/CodeGen/CodeGenPrepare.cpp"
, 2538, __extension__ __PRETTY_FUNCTION__))
;
2539 ScaledReg = V;
2540 Scale = 1;
2541 BaseOffs = 0;
2542 break;
2543 }
2544 }
2545};
2546
2547} // end anonymous namespace
2548
2549#ifndef NDEBUG
2550static inline raw_ostream &operator<<(raw_ostream &OS, const ExtAddrMode &AM) {
2551 AM.print(OS);
2552 return OS;
2553}
2554#endif
2555
2556#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
2557void ExtAddrMode::print(raw_ostream &OS) const {
2558 bool NeedPlus = false;
2559 OS << "[";
2560 if (InBounds)
2561 OS << "inbounds ";
2562 if (BaseGV) {
2563 OS << (NeedPlus ? " + " : "")
2564 << "GV:";
2565 BaseGV->printAsOperand(OS, /*PrintType=*/false);
2566 NeedPlus = true;
2567 }
2568
2569 if (BaseOffs) {
2570 OS << (NeedPlus ? " + " : "")
2571 << BaseOffs;
2572 NeedPlus = true;
2573 }
2574
2575 if (BaseReg) {
2576 OS << (NeedPlus ? " + " : "")
2577 << "Base:";
2578 BaseReg->printAsOperand(OS, /*PrintType=*/false);
2579 NeedPlus = true;
2580 }
2581 if (Scale) {
2582 OS << (NeedPlus ? " + " : "")
2583 << Scale << "*";
2584 ScaledReg->printAsOperand(OS, /*PrintType=*/false);
2585 }
2586
2587 OS << ']';
2588}
2589
2590LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void ExtAddrMode::dump() const {
2591 print(dbgs());
2592 dbgs() << '\n';
2593}
2594#endif
2595
2596namespace {
2597
2598/// This class provides transaction based operation on the IR.
2599/// Every change made through this class is recorded in the internal state and
2600/// can be undone (rollback) until commit is called.
2601/// CGP does not check if instructions could be speculatively executed when
2602/// moved. Preserving the original location would pessimize the debugging
2603/// experience, as well as negatively impact the quality of sample PGO.
2604class TypePromotionTransaction {
2605 /// This represents the common interface of the individual transaction.
2606 /// Each class implements the logic for doing one specific modification on
2607 /// the IR via the TypePromotionTransaction.
2608 class TypePromotionAction {
2609 protected:
2610 /// The Instruction modified.
2611 Instruction *Inst;
2612
2613 public:
2614 /// Constructor of the action.
2615 /// The constructor performs the related action on the IR.
2616 TypePromotionAction(Instruction *Inst) : Inst(Inst) {}
2617
2618 virtual ~TypePromotionAction() = default;
2619
2620 /// Undo the modification done by this action.
2621 /// When this method is called, the IR must be in the same state as it was
2622 /// before this action was applied.
2623 /// \pre Undoing the action works if and only if the IR is in the exact same
2624 /// state as it was directly after this action was applied.
2625 virtual void undo() = 0;
2626
2627 /// Advocate every change made by this action.
2628 /// When the results on the IR of the action are to be kept, it is important
2629 /// to call this function, otherwise hidden information may be kept forever.
2630 virtual void commit() {
2631 // Nothing to be done, this action is not doing anything.
2632 }
2633 };
2634
2635 /// Utility to remember the position of an instruction.
2636 class InsertionHandler {
2637 /// Position of an instruction.
2638 /// Either an instruction:
2639 /// - Is the first in a basic block: BB is used.
2640 /// - Has a previous instruction: PrevInst is used.
2641 union {
2642 Instruction *PrevInst;
2643 BasicBlock *BB;
2644 } Point;
2645
2646 /// Remember whether or not the instruction had a previous instruction.
2647 bool HasPrevInstruction;
2648
2649 public:
2650 /// Record the position of \p Inst.
2651 InsertionHandler(Instruction *Inst) {
2652 BasicBlock::iterator It = Inst->getIterator();
2653 HasPrevInstruction = (It != (Inst->getParent()->begin()));
2654 if (HasPrevInstruction)
2655 Point.PrevInst = &*--It;
2656 else
2657 Point.BB = Inst->getParent();
2658 }
2659
2660 /// Insert \p Inst at the recorded position.
2661 void insert(Instruction *Inst) {
2662 if (HasPrevInstruction) {
2663 if (Inst->getParent())
2664 Inst->removeFromParent();
2665 Inst->insertAfter(Point.PrevInst);
2666 } else {
2667 Instruction *Position = &*Point.BB->getFirstInsertionPt();
2668 if (Inst->getParent())
2669 Inst->moveBefore(Position);
2670 else
2671 Inst->insertBefore(Position);
2672 }
2673 }
2674 };
2675
2676 /// Move an instruction before another.
2677 class InstructionMoveBefore : public TypePromotionAction {
2678 /// Original position of the instruction.
2679 InsertionHandler Position;
2680
2681 public:
2682 /// Move \p Inst before \p Before.
2683 InstructionMoveBefore(Instruction *Inst, Instruction *Before)
2684 : TypePromotionAction(Inst), Position(Inst) {
2685 LLVM_DEBUG(dbgs() << "Do: move: " << *Inst << "\nbefore: " << *Beforedo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: move: " << *
Inst << "\nbefore: " << *Before << "\n"; } }
while (false)
2686 << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: move: " << *
Inst << "\nbefore: " << *Before << "\n"; } }
while (false)
;
2687 Inst->moveBefore(Before);
2688 }
2689
2690 /// Move the instruction back to its original position.
2691 void undo() override {
2692 LLVM_DEBUG(dbgs() << "Undo: moveBefore: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: moveBefore: " <<
*Inst << "\n"; } } while (false)
;
2693 Position.insert(Inst);
2694 }
2695 };
2696
2697 /// Set the operand of an instruction with a new value.
2698 class OperandSetter : public TypePromotionAction {
2699 /// Original operand of the instruction.
2700 Value *Origin;
2701
2702 /// Index of the modified instruction.
2703 unsigned Idx;
2704
2705 public:
2706 /// Set \p Idx operand of \p Inst with \p NewVal.
2707 OperandSetter(Instruction *Inst, unsigned Idx, Value *NewVal)
2708 : TypePromotionAction(Inst), Idx(Idx) {
2709 LLVM_DEBUG(dbgs() << "Do: setOperand: " << Idx << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: setOperand: " <<
Idx << "\n" << "for:" << *Inst << "\n"
<< "with:" << *NewVal << "\n"; } } while (
false)
2710 << "for:" << *Inst << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: setOperand: " <<
Idx << "\n" << "for:" << *Inst << "\n"
<< "with:" << *NewVal << "\n"; } } while (
false)
2711 << "with:" << *NewVal << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: setOperand: " <<
Idx << "\n" << "for:" << *Inst << "\n"
<< "with:" << *NewVal << "\n"; } } while (
false)
;
2712 Origin = Inst->getOperand(Idx);
2713 Inst->setOperand(Idx, NewVal);
2714 }
2715
2716 /// Restore the original value of the instruction.
2717 void undo() override {
2718 LLVM_DEBUG(dbgs() << "Undo: setOperand:" << Idx << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: setOperand:" <<
Idx << "\n" << "for: " << *Inst << "\n"
<< "with: " << *Origin << "\n"; } } while (
false)
2719 << "for: " << *Inst << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: setOperand:" <<
Idx << "\n" << "for: " << *Inst << "\n"
<< "with: " << *Origin << "\n"; } } while (
false)
2720 << "with: " << *Origin << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: setOperand:" <<
Idx << "\n" << "for: " << *Inst << "\n"
<< "with: " << *Origin << "\n"; } } while (
false)
;
2721 Inst->setOperand(Idx, Origin);
2722 }
2723 };
2724
2725 /// Hide the operands of an instruction.
2726 /// Do as if this instruction was not using any of its operands.
2727 class OperandsHider : public TypePromotionAction {
2728 /// The list of original operands.
2729 SmallVector<Value *, 4> OriginalValues;
2730
2731 public:
2732 /// Remove \p Inst from the uses of the operands of \p Inst.
2733 OperandsHider(Instruction *Inst) : TypePromotionAction(Inst) {
2734 LLVM_DEBUG(dbgs() << "Do: OperandsHider: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: OperandsHider: " <<
*Inst << "\n"; } } while (false)
;
2735 unsigned NumOpnds = Inst->getNumOperands();
2736 OriginalValues.reserve(NumOpnds);
2737 for (unsigned It = 0; It < NumOpnds; ++It) {
2738 // Save the current operand.
2739 Value *Val = Inst->getOperand(It);
2740 OriginalValues.push_back(Val);
2741 // Set a dummy one.
2742 // We could use OperandSetter here, but that would imply an overhead
2743 // that we are not willing to pay.
2744 Inst->setOperand(It, UndefValue::get(Val->getType()));
2745 }
2746 }
2747
2748 /// Restore the original list of uses.
2749 void undo() override {
2750 LLVM_DEBUG(dbgs() << "Undo: OperandsHider: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: OperandsHider: "
<< *Inst << "\n"; } } while (false)
;
2751 for (unsigned It = 0, EndIt = OriginalValues.size(); It != EndIt; ++It)
2752 Inst->setOperand(It, OriginalValues[It]);
2753 }
2754 };
2755
2756 /// Build a truncate instruction.
2757 class TruncBuilder : public TypePromotionAction {
2758 Value *Val;
2759
2760 public:
2761 /// Build a truncate instruction of \p Opnd producing a \p Ty
2762 /// result.
2763 /// trunc Opnd to Ty.
2764 TruncBuilder(Instruction *Opnd, Type *Ty) : TypePromotionAction(Opnd) {
2765 IRBuilder<> Builder(Opnd);
2766 Builder.SetCurrentDebugLocation(DebugLoc());
2767 Val = Builder.CreateTrunc(Opnd, Ty, "promoted");
2768 LLVM_DEBUG(dbgs() << "Do: TruncBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: TruncBuilder: " <<
*Val << "\n"; } } while (false)
;
2769 }
2770
2771 /// Get the built value.
2772 Value *getBuiltValue() { return Val; }
2773
2774 /// Remove the built instruction.
2775 void undo() override {
2776 LLVM_DEBUG(dbgs() << "Undo: TruncBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: TruncBuilder: " <<
*Val << "\n"; } } while (false)
;
2777 if (Instruction *IVal = dyn_cast<Instruction>(Val))
2778 IVal->eraseFromParent();
2779 }
2780 };
2781
2782 /// Build a sign extension instruction.
2783 class SExtBuilder : public TypePromotionAction {
2784 Value *Val;
2785
2786 public:
2787 /// Build a sign extension instruction of \p Opnd producing a \p Ty
2788 /// result.
2789 /// sext Opnd to Ty.
2790 SExtBuilder(Instruction *InsertPt, Value *Opnd, Type *Ty)
2791 : TypePromotionAction(InsertPt) {
2792 IRBuilder<> Builder(InsertPt);
2793 Val = Builder.CreateSExt(Opnd, Ty, "promoted");
2794 LLVM_DEBUG(dbgs() << "Do: SExtBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: SExtBuilder: " <<
*Val << "\n"; } } while (false)
;
2795 }
2796
2797 /// Get the built value.
2798 Value *getBuiltValue() { return Val; }
2799
2800 /// Remove the built instruction.
2801 void undo() override {
2802 LLVM_DEBUG(dbgs() << "Undo: SExtBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: SExtBuilder: " <<
*Val << "\n"; } } while (false)
;
2803 if (Instruction *IVal = dyn_cast<Instruction>(Val))
2804 IVal->eraseFromParent();
2805 }
2806 };
2807
2808 /// Build a zero extension instruction.
2809 class ZExtBuilder : public TypePromotionAction {
2810 Value *Val;
2811
2812 public:
2813 /// Build a zero extension instruction of \p Opnd producing a \p Ty
2814 /// result.
2815 /// zext Opnd to Ty.
2816 ZExtBuilder(Instruction *InsertPt, Value *Opnd, Type *Ty)
2817 : TypePromotionAction(InsertPt) {
2818 IRBuilder<> Builder(InsertPt);
2819 Builder.SetCurrentDebugLocation(DebugLoc());
2820 Val = Builder.CreateZExt(Opnd, Ty, "promoted");
2821 LLVM_DEBUG(dbgs() << "Do: ZExtBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: ZExtBuilder: " <<
*Val << "\n"; } } while (false)
;
2822 }
2823
2824 /// Get the built value.
2825 Value *getBuiltValue() { return Val; }
2826
2827 /// Remove the built instruction.
2828 void undo() override {
2829 LLVM_DEBUG(dbgs() << "Undo: ZExtBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: ZExtBuilder: " <<
*Val << "\n"; } } while (false)
;
2830 if (Instruction *IVal = dyn_cast<Instruction>(Val))
2831 IVal->eraseFromParent();
2832 }
2833 };
2834
2835 /// Mutate an instruction to another type.
2836 class TypeMutator : public TypePromotionAction {
2837 /// Record the original type.
2838 Type *OrigTy;
2839
2840 public:
2841 /// Mutate the type of \p Inst into \p NewTy.
2842 TypeMutator(Instruction *Inst, Type *NewTy)
2843 : TypePromotionAction(Inst), OrigTy(Inst->getType()) {
2844 LLVM_DEBUG(dbgs() << "Do: MutateType: " << *Inst << " with " << *NewTydo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: MutateType: " <<
*Inst << " with " << *NewTy << "\n"; } } while
(false)
2845 << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: MutateType: " <<
*Inst << " with " << *NewTy << "\n"; } } while
(false)
;
2846 Inst->mutateType(NewTy);
2847 }
2848
2849 /// Mutate the instruction back to its original type.
2850 void undo() override {
2851 LLVM_DEBUG(dbgs() << "Undo: MutateType: " << *Inst << " with " << *OrigTydo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: MutateType: " <<
*Inst << " with " << *OrigTy << "\n"; } } while
(false)
2852 << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: MutateType: " <<
*Inst << " with " << *OrigTy << "\n"; } } while
(false)
;
2853 Inst->mutateType(OrigTy);
2854 }
2855 };
2856
2857 /// Replace the uses of an instruction by another instruction.
2858 class UsesReplacer : public TypePromotionAction {
2859 /// Helper structure to keep track of the replaced uses.
2860 struct InstructionAndIdx {
2861 /// The instruction using the instruction.
2862 Instruction *Inst;
2863
2864 /// The index where this instruction is used for Inst.
2865 unsigned Idx;
2866
2867 InstructionAndIdx(Instruction *Inst, unsigned Idx)
2868 : Inst(Inst), Idx(Idx) {}
2869 };
2870
2871 /// Keep track of the original uses (pair Instruction, Index).
2872 SmallVector<InstructionAndIdx, 4> OriginalUses;
2873 /// Keep track of the debug users.
2874 SmallVector<DbgValueInst *, 1> DbgValues;
2875
2876 /// Keep track of the new value so that we can undo it by replacing
2877 /// instances of the new value with the original value.
2878 Value *New;
2879
2880 using use_iterator = SmallVectorImpl<InstructionAndIdx>::iterator;
2881
2882 public:
2883 /// Replace all the use of \p Inst by \p New.
2884 UsesReplacer(Instruction *Inst, Value *New)
2885 : TypePromotionAction(Inst), New(New) {
2886 LLVM_DEBUG(dbgs() << "Do: UsersReplacer: " << *Inst << " with " << *Newdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: UsersReplacer: " <<
*Inst << " with " << *New << "\n"; } } while
(false)
2887 << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: UsersReplacer: " <<
*Inst << " with " << *New << "\n"; } } while
(false)
;
2888 // Record the original uses.
2889 for (Use &U : Inst->uses()) {
2890 Instruction *UserI = cast<Instruction>(U.getUser());
2891 OriginalUses.push_back(InstructionAndIdx(UserI, U.getOperandNo()));
2892 }
2893 // Record the debug uses separately. They are not in the instruction's
2894 // use list, but they are replaced by RAUW.
2895 findDbgValues(DbgValues, Inst);
2896
2897 // Now, we can replace the uses.
2898 Inst->replaceAllUsesWith(New);
2899 }
2900
2901 /// Reassign the original uses of Inst to Inst.
2902 void undo() override {
2903 LLVM_DEBUG(dbgs() << "Undo: UsersReplacer: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: UsersReplacer: "
<< *Inst << "\n"; } } while (false)
;
2904 for (InstructionAndIdx &Use : OriginalUses)
2905 Use.Inst->setOperand(Use.Idx, Inst);
2906 // RAUW has replaced all original uses with references to the new value,
2907 // including the debug uses. Since we are undoing the replacements,
2908 // the original debug uses must also be reinstated to maintain the
2909 // correctness and utility of debug value instructions.
2910 for (auto *DVI : DbgValues)
2911 DVI->replaceVariableLocationOp(New, Inst);
2912 }
2913 };
2914
2915 /// Remove an instruction from the IR.
2916 class InstructionRemover : public TypePromotionAction {
2917 /// Original position of the instruction.
2918 InsertionHandler Inserter;
2919
2920 /// Helper structure to hide all the link to the instruction. In other
2921 /// words, this helps to do as if the instruction was removed.
2922 OperandsHider Hider;
2923
2924 /// Keep track of the uses replaced, if any.
2925 UsesReplacer *Replacer = nullptr;
2926
2927 /// Keep track of instructions removed.
2928 SetOfInstrs &RemovedInsts;
2929
2930 public:
2931 /// Remove all reference of \p Inst and optionally replace all its
2932 /// uses with New.
2933 /// \p RemovedInsts Keep track of the instructions removed by this Action.
2934 /// \pre If !Inst->use_empty(), then New != nullptr
2935 InstructionRemover(Instruction *Inst, SetOfInstrs &RemovedInsts,
2936 Value *New = nullptr)
2937 : TypePromotionAction(Inst), Inserter(Inst), Hider(Inst),
2938 RemovedInsts(RemovedInsts) {
2939 if (New)
2940 Replacer = new UsesReplacer(Inst, New);
2941 LLVM_DEBUG(dbgs() << "Do: InstructionRemover: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: InstructionRemover: "
<< *Inst << "\n"; } } while (false)
;
2942 RemovedInsts.insert(Inst);
2943 /// The instructions removed here will be freed after completing
2944 /// optimizeBlock() for all blocks as we need to keep track of the
2945 /// removed instructions during promotion.
2946 Inst->removeFromParent();
2947 }
2948
2949 ~InstructionRemover() override { delete Replacer; }
2950
2951 /// Resurrect the instruction and reassign it to the proper uses if
2952 /// new value was provided when build this action.
2953 void undo() override {
2954 LLVM_DEBUG(dbgs() << "Undo: InstructionRemover: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: InstructionRemover: "
<< *Inst << "\n"; } } while (false)
;
2955 Inserter.insert(Inst);
2956 if (Replacer)
2957 Replacer->undo();
2958 Hider.undo();
2959 RemovedInsts.erase(Inst);
2960 }
2961 };
2962
2963public:
2964 /// Restoration point.
2965 /// The restoration point is a pointer to an action instead of an iterator
2966 /// because the iterator may be invalidated but not the pointer.
2967 using ConstRestorationPt = const TypePromotionAction *;
2968
2969 TypePromotionTransaction(SetOfInstrs &RemovedInsts)
2970 : RemovedInsts(RemovedInsts) {}
2971
2972 /// Advocate every changes made in that transaction. Return true if any change
2973 /// happen.
2974 bool commit();
2975
2976 /// Undo all the changes made after the given point.
2977 void rollback(ConstRestorationPt Point);
2978
2979 /// Get the current restoration point.
2980 ConstRestorationPt getRestorationPoint() const;
2981
2982 /// \name API for IR modification with state keeping to support rollback.
2983 /// @{
2984 /// Same as Instruction::setOperand.
2985 void setOperand(Instruction *Inst, unsigned Idx, Value *NewVal);
2986
2987 /// Same as Instruction::eraseFromParent.
2988 void eraseInstruction(Instruction *Inst, Value *NewVal = nullptr);
2989
2990 /// Same as Value::replaceAllUsesWith.
2991 void replaceAllUsesWith(Instruction *Inst, Value *New);
2992
2993 /// Same as Value::mutateType.
2994 void mutateType(Instruction *Inst, Type *NewTy);
2995
2996 /// Same as IRBuilder::createTrunc.
2997 Value *createTrunc(Instruction *Opnd, Type *Ty);
2998
2999 /// Same as IRBuilder::createSExt.
3000 Value *createSExt(Instruction *Inst, Value *Opnd, Type *Ty);
3001
3002 /// Same as IRBuilder::createZExt.
3003 Value *createZExt(Instruction *Inst, Value *Opnd, Type *Ty);
3004
3005 /// Same as Instruction::moveBefore.
3006 void moveBefore(Instruction *Inst, Instruction *Before);
3007 /// @}
3008
3009private:
3010 /// The ordered list of actions made so far.
3011 SmallVector<std::unique_ptr<TypePromotionAction>, 16> Actions;
3012
3013 using CommitPt = SmallVectorImpl<std::unique_ptr<TypePromotionAction>>::iterator;
3014
3015 SetOfInstrs &RemovedInsts;
3016};
3017
3018} // end anonymous namespace
3019
3020void TypePromotionTransaction::setOperand(Instruction *Inst, unsigned Idx,
3021 Value *NewVal) {
3022 Actions.push_back(std::make_unique<TypePromotionTransaction::OperandSetter>(
3023 Inst, Idx, NewVal));
3024}
3025
3026void TypePromotionTransaction::eraseInstruction(Instruction *Inst,
3027 Value *NewVal) {
3028 Actions.push_back(
3029 std::make_unique<TypePromotionTransaction::InstructionRemover>(
3030 Inst, RemovedInsts, NewVal));
3031}
3032
3033void TypePromotionTransaction::replaceAllUsesWith(Instruction *Inst,
3034 Value *New) {
3035 Actions.push_back(
3036 std::make_unique<TypePromotionTransaction::UsesReplacer>(Inst, New));
3037}
3038
3039void TypePromotionTransaction::mutateType(Instruction *Inst, Type *NewTy) {
3040 Actions.push_back(
3041 std::make_unique<TypePromotionTransaction::TypeMutator>(Inst, NewTy));
3042}
3043
3044Value *TypePromotionTransaction::createTrunc(Instruction *Opnd,
3045 Type *Ty) {
3046 std::unique_ptr<TruncBuilder> Ptr(new TruncBuilder(Opnd, Ty));
3047 Value *Val = Ptr->getBuiltValue();
3048 Actions.push_back(std::move(Ptr));
3049 return Val;
3050}
3051
3052Value *TypePromotionTransaction::createSExt(Instruction *Inst,
3053 Value *Opnd, Type *Ty) {
3054 std::unique_ptr<SExtBuilder> Ptr(new SExtBuilder(Inst, Opnd, Ty));
3055 Value *Val = Ptr->getBuiltValue();
3056 Actions.push_back(std::move(Ptr));
3057 return Val;
3058}
3059
3060Value *TypePromotionTransaction::createZExt(Instruction *Inst,
3061 Value *Opnd, Type *Ty) {
3062 std::unique_ptr<ZExtBuilder> Ptr(new ZExtBuilder(Inst, Opnd, Ty));
3063 Value *Val = Ptr->getBuiltValue();
3064 Actions.push_back(std::move(Ptr));
3065 return Val;
3066}
3067
3068void TypePromotionTransaction::moveBefore(Instruction *Inst,
3069 Instruction *Before) {
3070 Actions.push_back(
3071 std::make_unique<TypePromotionTransaction::InstructionMoveBefore>(
3072 Inst, Before));
3073}
3074
3075TypePromotionTransaction::ConstRestorationPt
3076TypePromotionTransaction::getRestorationPoint() const {
3077 return !Actions.empty() ? Actions.back().get() : nullptr;
3078}
3079
3080bool TypePromotionTransaction::commit() {
3081 for (std::unique_ptr<TypePromotionAction> &Action : Actions)
3082 Action->commit();
3083 bool Modified = !Actions.empty();
3084 Actions.clear();
3085 return Modified;
3086}
3087
3088void TypePromotionTransaction::rollback(
3089 TypePromotionTransaction::ConstRestorationPt Point) {
3090 while (!Actions.empty() && Point != Actions.back().get()) {
3091 std::unique_ptr<TypePromotionAction> Curr = Actions.pop_back_val();
3092 Curr->undo();
3093 }
3094}
3095
3096namespace {
3097
3098/// A helper class for matching addressing modes.
3099///
3100/// This encapsulates the logic for matching the target-legal addressing modes.
3101class AddressingModeMatcher {
3102 SmallVectorImpl<Instruction*> &AddrModeInsts;
3103 const TargetLowering &TLI;
3104 const TargetRegisterInfo &TRI;
3105 const DataLayout &DL;
3106 const LoopInfo &LI;
3107 const std::function<const DominatorTree &()> getDTFn;
3108
3109 /// AccessTy/MemoryInst - This is the type for the access (e.g. double) and
3110 /// the memory instruction that we're computing this address for.
3111 Type *AccessTy;
3112 unsigned AddrSpace;
3113 Instruction *MemoryInst;
3114
3115 /// This is the addressing mode that we're building up. This is
3116 /// part of the return value of this addressing mode matching stuff.
3117 ExtAddrMode &AddrMode;
3118
3119 /// The instructions inserted by other CodeGenPrepare optimizations.
3120 const SetOfInstrs &InsertedInsts;
3121
3122 /// A map from the instructions to their type before promotion.
3123 InstrToOrigTy &PromotedInsts;
3124
3125 /// The ongoing transaction where every action should be registered.
3126 TypePromotionTransaction &TPT;
3127
3128 // A GEP which has too large offset to be folded into the addressing mode.
3129 std::pair<AssertingVH<GetElementPtrInst>, int64_t> &LargeOffsetGEP;
3130
3131 /// This is set to true when we should not do profitability checks.
3132 /// When true, IsProfitableToFoldIntoAddressingMode always returns true.
3133 bool IgnoreProfitability;
3134
3135 /// True if we are optimizing for size.
3136 bool OptSize;
3137
3138 ProfileSummaryInfo *PSI;
3139 BlockFrequencyInfo *BFI;
3140
3141 AddressingModeMatcher(
3142 SmallVectorImpl<Instruction *> &AMI, const TargetLowering &TLI,
3143 const TargetRegisterInfo &TRI, const LoopInfo &LI,
3144 const std::function<const DominatorTree &()> getDTFn,
3145 Type *AT, unsigned AS, Instruction *MI, ExtAddrMode &AM,
3146 const SetOfInstrs &InsertedInsts, InstrToOrigTy &PromotedInsts,
3147 TypePromotionTransaction &TPT,
3148 std::pair<AssertingVH<GetElementPtrInst>, int64_t> &LargeOffsetGEP,
3149 bool OptSize, ProfileSummaryInfo *PSI, BlockFrequencyInfo *BFI)
3150 : AddrModeInsts(AMI), TLI(TLI), TRI(TRI),
3151 DL(MI->getModule()->getDataLayout()), LI(LI), getDTFn(getDTFn),
3152 AccessTy(AT), AddrSpace(AS), MemoryInst(MI), AddrMode(AM),
3153 InsertedInsts(InsertedInsts), PromotedInsts(PromotedInsts), TPT(TPT),
3154 LargeOffsetGEP(LargeOffsetGEP), OptSize(OptSize), PSI(PSI), BFI(BFI) {
3155 IgnoreProfitability = false;
3156 }
3157
3158public:
3159 /// Find the maximal addressing mode that a load/store of V can fold,
3160 /// give an access type of AccessTy. This returns a list of involved
3161 /// instructions in AddrModeInsts.
3162 /// \p InsertedInsts The instructions inserted by other CodeGenPrepare
3163 /// optimizations.
3164 /// \p PromotedInsts maps the instructions to their type before promotion.
3165 /// \p The ongoing transaction where every action should be registered.
3166 static ExtAddrMode
3167 Match(Value *V, Type *AccessTy, unsigned AS, Instruction *MemoryInst,
3168 SmallVectorImpl<Instruction *> &AddrModeInsts,
3169 const TargetLowering &TLI, const LoopInfo &LI,
3170 const std::function<const DominatorTree &()> getDTFn,
3171 const TargetRegisterInfo &TRI, const SetOfInstrs &InsertedInsts,
3172 InstrToOrigTy &PromotedInsts, TypePromotionTransaction &TPT,
3173 std::pair<AssertingVH<GetElementPtrInst>, int64_t> &LargeOffsetGEP,
3174 bool OptSize, ProfileSummaryInfo *PSI, BlockFrequencyInfo *BFI) {
3175 ExtAddrMode Result;
3176
3177 bool Success = AddressingModeMatcher(
3178 AddrModeInsts, TLI, TRI, LI, getDTFn, AccessTy, AS, MemoryInst, Result,
3179 InsertedInsts, PromotedInsts, TPT, LargeOffsetGEP, OptSize, PSI,
3180 BFI).matchAddr(V, 0);
3181 (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*?\""
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 3181, __extension__ __PRETTY_FUNCTION__
))
;
3182 return Result;
3183 }
3184
3185private:
3186 bool matchScaledValue(Value *ScaleReg, int64_t Scale, unsigned Depth);
3187 bool matchAddr(Value *Addr, unsigned Depth);
3188 bool matchOperationAddr(User *AddrInst, unsigned Opcode, unsigned Depth,
3189 bool *MovedAway = nullptr);
3190 bool isProfitableToFoldIntoAddressingMode(Instruction *I,
3191 ExtAddrMode &AMBefore,
3192 ExtAddrMode &AMAfter);
3193 bool valueAlreadyLiveAtInst(Value *Val, Value *KnownLive1, Value *KnownLive2);
3194 bool isPromotionProfitable(unsigned NewCost, unsigned OldCost,
3195 Value *PromotedOperand) const;
3196};
3197
3198class PhiNodeSet;
3199
3200/// An iterator for PhiNodeSet.
3201class PhiNodeSetIterator {
3202 PhiNodeSet * const Set;
3203 size_t CurrentIndex = 0;
3204
3205public:
3206 /// The constructor. Start should point to either a valid element, or be equal
3207 /// to the size of the underlying SmallVector of the PhiNodeSet.
3208 PhiNodeSetIterator(PhiNodeSet * const Set, size_t Start);
3209 PHINode * operator*() const;
3210 PhiNodeSetIterator& operator++();
3211 bool operator==(const PhiNodeSetIterator &RHS) const;
3212 bool operator!=(const PhiNodeSetIterator &RHS) const;
3213};
3214
3215/// Keeps a set of PHINodes.
3216///
3217/// This is a minimal set implementation for a specific use case:
3218/// It is very fast when there are very few elements, but also provides good
3219/// performance when there are many. It is similar to SmallPtrSet, but also
3220/// provides iteration by insertion order, which is deterministic and stable
3221/// across runs. It is also similar to SmallSetVector, but provides removing
3222/// elements in O(1) time. This is achieved by not actually removing the element
3223/// from the underlying vector, so comes at the cost of using more memory, but
3224/// that is fine, since PhiNodeSets are used as short lived objects.
3225class PhiNodeSet {
3226 friend class PhiNodeSetIterator;
3227
3228 using MapType = SmallDenseMap<PHINode *, size_t, 32>;
3229 using iterator = PhiNodeSetIterator;
3230
3231 /// Keeps the elements in the order of their insertion in the underlying
3232 /// vector. To achieve constant time removal, it never deletes any element.
3233 SmallVector<PHINode *, 32> NodeList;
3234
3235 /// Keeps the elements in the underlying set implementation. This (and not the
3236 /// NodeList defined above) is the source of truth on whether an element
3237 /// is actually in the collection.
3238 MapType NodeMap;
3239
3240 /// Points to the first valid (not deleted) element when the set is not empty
3241 /// and the value is not zero. Equals to the size of the underlying vector
3242 /// when the set is empty. When the value is 0, as in the beginning, the
3243 /// first element may or may not be valid.
3244 size_t FirstValidElement = 0;
3245
3246public:
3247 /// Inserts a new element to the collection.
3248 /// \returns true if the element is actually added, i.e. was not in the
3249 /// collection before the operation.
3250 bool insert(PHINode *Ptr) {
3251 if (NodeMap.insert(std::make_pair(Ptr, NodeList.size())).second) {
3252 NodeList.push_back(Ptr);
3253 return true;
3254 }
3255 return false;
3256 }
3257
3258 /// Removes the element from the collection.
3259 /// \returns whether the element is actually removed, i.e. was in the
3260 /// collection before the operation.
3261 bool erase(PHINode *Ptr) {
3262 if (NodeMap.erase(Ptr)) {
3263 SkipRemovedElements(FirstValidElement);
3264 return true;
3265 }
3266 return false;
3267 }
3268
3269 /// Removes all elements and clears the collection.
3270 void clear() {
3271 NodeMap.clear();
3272 NodeList.clear();
3273 FirstValidElement = 0;
3274 }
3275
3276 /// \returns an iterator that will iterate the elements in the order of
3277 /// insertion.
3278 iterator begin() {
3279 if (FirstValidElement == 0)
3280 SkipRemovedElements(FirstValidElement);
3281 return PhiNodeSetIterator(this, FirstValidElement);
3282 }
3283
3284 /// \returns an iterator that points to the end of the collection.
3285 iterator end() { return PhiNodeSetIterator(this, NodeList.size()); }
3286
3287 /// Returns the number of elements in the collection.
3288 size_t size() const {
3289 return NodeMap.size();
3290 }
3291
3292 /// \returns 1 if the given element is in the collection, and 0 if otherwise.
3293 size_t count(PHINode *Ptr) const {
3294 return NodeMap.count(Ptr);
3295 }
3296
3297private:
3298 /// Updates the CurrentIndex so that it will point to a valid element.
3299 ///
3300 /// If the element of NodeList at CurrentIndex is valid, it does not
3301 /// change it. If there are no more valid elements, it updates CurrentIndex
3302 /// to point to the end of the NodeList.
3303 void SkipRemovedElements(size_t &CurrentIndex) {
3304 while (CurrentIndex < NodeList.size()) {
3305 auto it = NodeMap.find(NodeList[CurrentIndex]);
3306 // If the element has been deleted and added again later, NodeMap will
3307 // point to a different index, so CurrentIndex will still be invalid.
3308 if (it != NodeMap.end() && it->second == CurrentIndex)
3309 break;
3310 ++CurrentIndex;
3311 }
3312 }
3313};
3314
3315PhiNodeSetIterator::PhiNodeSetIterator(PhiNodeSet *const Set, size_t Start)
3316 : Set(Set), CurrentIndex(Start) {}
3317
3318PHINode * PhiNodeSetIterator::operator*() const {
3319 assert(CurrentIndex < Set->NodeList.size() &&(static_cast <bool> (CurrentIndex < Set->NodeList
.size() && "PhiNodeSet access out of range") ? void (
0) : __assert_fail ("CurrentIndex < Set->NodeList.size() && \"PhiNodeSet access out of range\""
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 3320, __extension__ __PRETTY_FUNCTION__
))
3320 "PhiNodeSet access out of range")(static_cast <bool> (CurrentIndex < Set->NodeList
.size() && "PhiNodeSet access out of range") ? void (
0) : __assert_fail ("CurrentIndex < Set->NodeList.size() && \"PhiNodeSet access out of range\""
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 3320, __extension__ __PRETTY_FUNCTION__
))
;
3321 return Set->NodeList[CurrentIndex];
3322}
3323
3324PhiNodeSetIterator& PhiNodeSetIterator::operator++() {
3325 assert(CurrentIndex < Set->NodeList.size() &&(static_cast <bool> (CurrentIndex < Set->NodeList
.size() && "PhiNodeSet access out of range") ? void (
0) : __assert_fail ("CurrentIndex < Set->NodeList.size() && \"PhiNodeSet access out of range\""
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 3326, __extension__ __PRETTY_FUNCTION__
))
3326 "PhiNodeSet access out of range")(static_cast <bool> (CurrentIndex < Set->NodeList
.size() && "PhiNodeSet access out of range") ? void (
0) : __assert_fail ("CurrentIndex < Set->NodeList.size() && \"PhiNodeSet access out of range\""
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 3326, __extension__ __PRETTY_FUNCTION__
))
;
3327 ++CurrentIndex;
3328 Set->SkipRemovedElements(CurrentIndex);
3329 return *this;
3330}
3331
3332bool PhiNodeSetIterator::operator==(const PhiNodeSetIterator &RHS) const {
3333 return CurrentIndex == RHS.CurrentIndex;
3334}
3335
3336bool PhiNodeSetIterator::operator!=(const PhiNodeSetIterator &RHS) const {
3337 return !((*this) == RHS);
3338}
3339
3340/// Keep track of simplification of Phi nodes.
3341/// Accept the set of all phi nodes and erase phi node from this set
3342/// if it is simplified.
3343class SimplificationTracker {
3344 DenseMap<Value *, Value *> Storage;
3345 const SimplifyQuery &SQ;
3346 // Tracks newly created Phi nodes. The elements are iterated by insertion
3347 // order.
3348 PhiNodeSet AllPhiNodes;
3349 // Tracks newly created Select nodes.
3350 SmallPtrSet<SelectInst *, 32> AllSelectNodes;
3351
3352public:
3353 SimplificationTracker(const SimplifyQuery &sq)
3354 : SQ(sq) {}
3355
3356 Value *Get(Value *V) {
3357 do {
3358 auto SV = Storage.find(V);
3359 if (SV == Storage.end())
3360 return V;
3361 V = SV->second;
3362 } while (true);
3363 }
3364
3365 Value *Simplify(Value *Val) {
3366 SmallVector<Value *, 32> WorkList;
3367 SmallPtrSet<Value *, 32> Visited;
3368 WorkList.push_back(Val);
3369 while (!WorkList.empty()) {
3370 auto *P = WorkList.pop_back_val();
3371 if (!Visited.insert(P).second)
3372 continue;
3373 if (auto *PI = dyn_cast<Instruction>(P))
3374 if (Value *V = SimplifyInstruction(cast<Instruction>(PI), SQ)) {
3375 for (auto *U : PI->users())
3376 WorkList.push_back(cast<Value>(U));
3377 Put(PI, V);
3378 PI->replaceAllUsesWith(V);
3379 if (auto *PHI = dyn_cast<PHINode>(PI))
3380 AllPhiNodes.erase(PHI);
3381 if (auto *Select = dyn_cast<SelectInst>(PI))
3382 AllSelectNodes.erase(Select);
3383 PI->eraseFromParent();
3384 }
3385 }
3386 return Get(Val);
3387 }
3388
3389 void Put(Value *From, Value *To) {
3390 Storage.insert({ From, To });
3391 }
3392
3393 void ReplacePhi(PHINode *From, PHINode *To) {
3394 Value* OldReplacement = Get(From);
3395 while (OldReplacement != From) {
3396 From = To;
3397 To = dyn_cast<PHINode>(OldReplacement);
3398 OldReplacement = Get(From);
3399 }
3400 assert(To && Get(To) == To && "Replacement PHI node is already replaced.")(static_cast <bool> (To && Get(To) == To &&
"Replacement PHI node is already replaced.") ? void (0) : __assert_fail
("To && Get(To) == To && \"Replacement PHI node is already replaced.\""
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 3400, __extension__ __PRETTY_FUNCTION__
))
;
3401 Put(From, To);
3402 From->replaceAllUsesWith(To);
3403 AllPhiNodes.erase(From);
3404 From->eraseFromParent();
3405 }
3406
3407 PhiNodeSet& newPhiNodes() { return AllPhiNodes; }
3408
3409 void insertNewPhi(PHINode *PN) { AllPhiNodes.insert(PN); }
3410
3411 void insertNewSelect(SelectInst *SI) { AllSelectNodes.insert(SI); }
3412
3413 unsigned countNewPhiNodes() const { return AllPhiNodes.size(); }
3414
3415 unsigned countNewSelectNodes() const { return AllSelectNodes.size(); }
3416
3417 void destroyNewNodes(Type *CommonType) {
3418 // For safe erasing, replace the uses with dummy value first.
3419 auto *Dummy = UndefValue::get(CommonType);
3420 for (auto *I : AllPhiNodes) {
3421 I->replaceAllUsesWith(Dummy);
3422 I->eraseFromParent();
3423 }
3424 AllPhiNodes.clear();
3425 for (auto *I : AllSelectNodes) {
3426 I->replaceAllUsesWith(Dummy);
3427 I->eraseFromParent();
3428 }
3429 AllSelectNodes.clear();
3430 }
3431};
3432
3433/// A helper class for combining addressing modes.
3434class AddressingModeCombiner {
3435 typedef DenseMap<Value *, Value *> FoldAddrToValueMapping;
3436 typedef std::pair<PHINode *, PHINode *> PHIPair;
3437
3438private:
3439 /// The addressing modes we've collected.
3440 SmallVector<ExtAddrMode, 16> AddrModes;
3441
3442 /// The field in which the AddrModes differ, when we have more than one.
3443 ExtAddrMode::FieldName DifferentField = ExtAddrMode::NoField;
3444
3445 /// Are the AddrModes that we have all just equal to their original values?
3446 bool AllAddrModesTrivial = true;
3447
3448 /// Common Type for all different fields in addressing modes.
3449 Type *CommonType;
3450
3451 /// SimplifyQuery for simplifyInstruction utility.
3452 const SimplifyQuery &SQ;
3453
3454 /// Original Address.
3455 Value *Original;
3456
3457public:
3458 AddressingModeCombiner(const SimplifyQuery &_SQ, Value *OriginalValue)
3459 : CommonType(nullptr), SQ(_SQ), Original(OriginalValue) {}
3460
3461 /// Get the combined AddrMode
3462 const ExtAddrMode &getAddrMode() const {
3463 return AddrModes[0];
3464 }
3465
3466 /// Add a new AddrMode if it's compatible with the AddrModes we already
3467 /// have.
3468 /// \return True iff we succeeded in doing so.
3469 bool addNewAddrMode(ExtAddrMode &NewAddrMode) {
3470 // Take note of if we have any non-trivial AddrModes, as we need to detect
3471 // when all AddrModes are trivial as then we would introduce a phi or select
3472 // which just duplicates what's already there.
3473 AllAddrModesTrivial = AllAddrModesTrivial && NewAddrMode.isTrivial();
3474
3475 // If this is the first addrmode then everything is fine.
3476 if (AddrModes.empty()) {
3477 AddrModes.emplace_back(NewAddrMode);
3478 return true;
3479 }
3480
3481 // Figure out how different this is from the other address modes, which we
3482 // can do just by comparing against the first one given that we only care
3483 // about the cumulative difference.
3484 ExtAddrMode::FieldName ThisDifferentField =
3485 AddrModes[0].compare(NewAddrMode);
3486 if (DifferentField == ExtAddrMode::NoField)
3487 DifferentField = ThisDifferentField;
3488 else if (DifferentField != ThisDifferentField)
3489 DifferentField = ExtAddrMode::MultipleFields;
3490
3491 // If NewAddrMode differs in more than one dimension we cannot handle it.
3492 bool CanHandle = DifferentField != ExtAddrMode::MultipleFields;
3493
3494 // If Scale Field is different then we reject.
3495 CanHandle = CanHandle && DifferentField != ExtAddrMode::ScaleField;
3496
3497 // We also must reject the case when base offset is different and
3498 // scale reg is not null, we cannot handle this case due to merge of
3499 // different offsets will be used as ScaleReg.
3500 CanHandle = CanHandle && (DifferentField != ExtAddrMode::BaseOffsField ||
3501 !NewAddrMode.ScaledReg);
3502
3503 // We also must reject the case when GV is different and BaseReg installed
3504 // due to we want to use base reg as a merge of GV values.
3505 CanHandle = CanHandle && (DifferentField != ExtAddrMode::BaseGVField ||
3506 !NewAddrMode.HasBaseReg);
3507
3508 // Even if NewAddMode is the same we still need to collect it due to
3509 // original value is different. And later we will need all original values
3510 // as anchors during finding the common Phi node.
3511 if (CanHandle)
3512 AddrModes.emplace_back(NewAddrMode);
3513 else
3514 AddrModes.clear();
3515
3516 return CanHandle;
3517 }
3518
3519 /// Combine the addressing modes we've collected into a single
3520 /// addressing mode.
3521 /// \return True iff we successfully combined them or we only had one so
3522 /// didn't need to combine them anyway.
3523 bool combineAddrModes() {
3524 // If we have no AddrModes then they can't be combined.
3525 if (AddrModes.size() == 0)
3526 return false;
3527
3528 // A single AddrMode can trivially be combined.
3529 if (AddrModes.size() == 1 || DifferentField == ExtAddrMode::NoField)
3530 return true;
3531
3532 // If the AddrModes we collected are all just equal to the value they are
3533 // derived from then combining them wouldn't do anything useful.
3534 if (AllAddrModesTrivial)
3535 return false;
3536
3537 if (!addrModeCombiningAllowed())
3538 return false;
3539
3540 // Build a map between <original value, basic block where we saw it> to
3541 // value of base register.
3542 // Bail out if there is no common type.
3543 FoldAddrToValueMapping Map;
3544 if (!initializeMap(Map))
3545 return false;
3546
3547 Value *CommonValue = findCommon(Map);
3548 if (CommonValue)
3549 AddrModes[0].SetCombinedField(DifferentField, CommonValue, AddrModes);
3550 return CommonValue != nullptr;
3551 }
3552
3553private:
3554 /// Initialize Map with anchor values. For address seen
3555 /// we set the value of different field saw in this address.
3556 /// At the same time we find a common type for different field we will
3557 /// use to create new Phi/Select nodes. Keep it in CommonType field.
3558 /// Return false if there is no common type found.
3559 bool initializeMap(FoldAddrToValueMapping &Map) {
3560 // Keep track of keys where the value is null. We will need to replace it
3561 // with constant null when we know the common type.
3562 SmallVector<Value *, 2> NullValue;
3563 Type *IntPtrTy = SQ.DL.getIntPtrType(AddrModes[0].OriginalValue->getType());
3564 for (auto &AM : AddrModes) {
3565 Value *DV = AM.GetFieldAsValue(DifferentField, IntPtrTy);
3566 if (DV) {
3567 auto *Type = DV->getType();
3568 if (CommonType && CommonType != Type)
3569 return false;
3570 CommonType = Type;
3571 Map[AM.OriginalValue] = DV;
3572 } else {
3573 NullValue.push_back(AM.OriginalValue);
3574 }
3575 }
3576 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!\""
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 3576, __extension__ __PRETTY_FUNCTION__
))
;
3577 for (auto *V : NullValue)
3578 Map[V] = Constant::getNullValue(CommonType);
3579 return true;
3580 }
3581
3582 /// We have mapping between value A and other value B where B was a field in
3583 /// addressing mode represented by A. Also we have an original value C
3584 /// representing an address we start with. Traversing from C through phi and
3585 /// selects we ended up with A's in a map. This utility function tries to find
3586 /// a value V which is a field in addressing mode C and traversing through phi
3587 /// nodes and selects we will end up in corresponded values B in a map.
3588 /// The utility will create a new Phi/Selects if needed.
3589 // The simple example looks as follows:
3590 // BB1:
3591 // p1 = b1 + 40
3592 // br cond BB2, BB3
3593 // BB2:
3594 // p2 = b2 + 40
3595 // br BB3
3596 // BB3:
3597 // p = phi [p1, BB1], [p2, BB2]
3598 // v = load p
3599 // Map is
3600 // p1 -> b1
3601 // p2 -> b2
3602 // Request is
3603 // p -> ?
3604 // The function tries to find or build phi [b1, BB1], [b2, BB2] in BB3.
3605 Value *findCommon(FoldAddrToValueMapping &Map) {
3606 // Tracks the simplification of newly created phi nodes. The reason we use
3607 // this mapping is because we will add new created Phi nodes in AddrToBase.
3608 // Simplification of Phi nodes is recursive, so some Phi node may
3609 // be simplified after we added it to AddrToBase. In reality this
3610 // simplification is possible only if original phi/selects were not
3611 // simplified yet.
3612 // Using this mapping we can find the current value in AddrToBase.
3613 SimplificationTracker ST(SQ);
3614
3615 // First step, DFS to create PHI nodes for all intermediate blocks.
3616 // Also fill traverse order for the second step.
3617 SmallVector<Value *, 32> TraverseOrder;
3618 InsertPlaceholders(Map, TraverseOrder, ST);
3619
3620 // Second Step, fill new nodes by merged values and simplify if possible.
3621 FillPlaceholders(Map, TraverseOrder, ST);
3622
3623 if (!AddrSinkNewSelects && ST.countNewSelectNodes() > 0) {
3624 ST.destroyNewNodes(CommonType);
3625 return nullptr;
3626 }
3627
3628 // Now we'd like to match New Phi nodes to existed ones.
3629 unsigned PhiNotMatchedCount = 0;
3630 if (!MatchPhiSet(ST, AddrSinkNewPhis, PhiNotMatchedCount)) {
3631 ST.destroyNewNodes(CommonType);
3632 return nullptr;
3633 }
3634
3635 auto *Result = ST.Get(Map.find(Original)->second);
3636 if (Result) {
3637 NumMemoryInstsPhiCreated += ST.countNewPhiNodes() + PhiNotMatchedCount;
3638 NumMemoryInstsSelectCreated += ST.countNewSelectNodes();
3639 }
3640 return Result;
3641 }
3642
3643 /// Try to match PHI node to Candidate.
3644 /// Matcher tracks the matched Phi nodes.
3645 bool MatchPhiNode(PHINode *PHI, PHINode *Candidate,
3646 SmallSetVector<PHIPair, 8> &Matcher,
3647 PhiNodeSet &PhiNodesToMatch) {
3648 SmallVector<PHIPair, 8> WorkList;
3649 Matcher.insert({ PHI, Candidate });
3650 SmallSet<PHINode *, 8> MatchedPHIs;
3651 MatchedPHIs.insert(PHI);
3652 WorkList.push_back({ PHI, Candidate });
3653 SmallSet<PHIPair, 8> Visited;
3654 while (!WorkList.empty()) {
3655 auto Item = WorkList.pop_back_val();
3656 if (!Visited.insert(Item).second)
3657 continue;
3658 // We iterate over all incoming values to Phi to compare them.
3659 // If values are different and both of them Phi and the first one is a
3660 // Phi we added (subject to match) and both of them is in the same basic
3661 // block then we can match our pair if values match. So we state that
3662 // these values match and add it to work list to verify that.
3663 for (auto B : Item.first->blocks()) {
3664 Value *FirstValue = Item.first->getIncomingValueForBlock(B);
3665 Value *SecondValue = Item.second->getIncomingValueForBlock(B);
3666 if (FirstValue == SecondValue)
3667 continue;
3668
3669 PHINode *FirstPhi = dyn_cast<PHINode>(FirstValue);
3670 PHINode *SecondPhi = dyn_cast<PHINode>(SecondValue);
3671
3672 // One of them is not Phi or
3673 // The first one is not Phi node from the set we'd like to match or
3674 // Phi nodes from different basic blocks then
3675 // we will not be able to match.
3676 if (!FirstPhi || !SecondPhi || !PhiNodesToMatch.count(FirstPhi) ||
3677 FirstPhi->getParent() != SecondPhi->getParent())
3678 return false;
3679
3680 // If we already matched them then continue.
3681 if (Matcher.count({ FirstPhi, SecondPhi }))
3682 continue;
3683 // So the values are different and does not match. So we need them to
3684 // match. (But we register no more than one match per PHI node, so that
3685 // we won't later try to replace them twice.)
3686 if (MatchedPHIs.insert(FirstPhi).second)
3687 Matcher.insert({ FirstPhi, SecondPhi });
3688 // But me must check it.
3689 WorkList.push_back({ FirstPhi, SecondPhi });
3690 }
3691 }
3692 return true;
3693 }
3694
3695 /// For the given set of PHI nodes (in the SimplificationTracker) try
3696 /// to find their equivalents.
3697 /// Returns false if this matching fails and creation of new Phi is disabled.
3698 bool MatchPhiSet(SimplificationTracker &ST, bool AllowNewPhiNodes,
3699 unsigned &PhiNotMatchedCount) {
3700 // Matched and PhiNodesToMatch iterate their elements in a deterministic
3701 // order, so the replacements (ReplacePhi) are also done in a deterministic
3702 // order.
3703 SmallSetVector<PHIPair, 8> Matched;
3704 SmallPtrSet<PHINode *, 8> WillNotMatch;
3705 PhiNodeSet &PhiNodesToMatch = ST.newPhiNodes();
3706 while (PhiNodesToMatch.size()) {
3707 PHINode *PHI = *PhiNodesToMatch.begin();
3708
3709 // Add us, if no Phi nodes in the basic block we do not match.
3710 WillNotMatch.clear();
3711 WillNotMatch.insert(PHI);
3712
3713 // Traverse all Phis until we found equivalent or fail to do that.
3714 bool IsMatched = false;
3715 for (auto &P : PHI->getParent()->phis()) {
3716 // Skip new Phi nodes.
3717 if (PhiNodesToMatch.count(&P))
3718 continue;
3719 if ((IsMatched = MatchPhiNode(PHI, &P, Matched, PhiNodesToMatch)))
3720 break;
3721 // If it does not match, collect all Phi nodes from matcher.
3722 // if we end up with no match, them all these Phi nodes will not match
3723 // later.
3724 for (auto M : Matched)
3725 WillNotMatch.insert(M.first);
3726 Matched.clear();
3727 }
3728 if (IsMatched) {
3729 // Replace all matched values and erase them.
3730 for (auto MV : Matched)
3731 ST.ReplacePhi(MV.first, MV.second);
3732 Matched.clear();
3733 continue;
3734 }
3735 // If we are not allowed to create new nodes then bail out.
3736 if (!AllowNewPhiNodes)
3737 return false;
3738 // Just remove all seen values in matcher. They will not match anything.
3739 PhiNotMatchedCount += WillNotMatch.size();
3740 for (auto *P : WillNotMatch)
3741 PhiNodesToMatch.erase(P);
3742 }
3743 return true;
3744 }
3745 /// Fill the placeholders with values from predecessors and simplify them.
3746 void FillPlaceholders(FoldAddrToValueMapping &Map,
3747 SmallVectorImpl<Value *> &TraverseOrder,
3748 SimplificationTracker &ST) {
3749 while (!TraverseOrder.empty()) {
3750 Value *Current = TraverseOrder.pop_back_val();
3751 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!!!\""
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 3751, __extension__ __PRETTY_FUNCTION__
))
;
3752 Value *V = Map[Current];
3753
3754 if (SelectInst *Select = dyn_cast<SelectInst>(V)) {
3755 // CurrentValue also must be Select.
3756 auto *CurrentSelect = cast<SelectInst>(Current);
3757 auto *TrueValue = CurrentSelect->getTrueValue();
3758 assert(Map.find(TrueValue) != Map.end() && "No True Value!")(static_cast <bool> (Map.find(TrueValue) != Map.end() &&
"No True Value!") ? void (0) : __assert_fail ("Map.find(TrueValue) != Map.end() && \"No True Value!\""
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 3758, __extension__ __PRETTY_FUNCTION__
))
;
3759 Select->setTrueValue(ST.Get(Map[TrueValue]));
3760 auto *FalseValue = CurrentSelect->getFalseValue();
3761 assert(Map.find(FalseValue) != Map.end() && "No False Value!")(static_cast <bool> (Map.find(FalseValue) != Map.end() &&
"No False Value!") ? void (0) : __assert_fail ("Map.find(FalseValue) != Map.end() && \"No False Value!\""
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 3761, __extension__ __PRETTY_FUNCTION__
))
;
3762 Select->setFalseValue(ST.Get(Map[FalseValue]));
3763 } else {
3764 // Must be a Phi node then.
3765 auto *PHI = cast<PHINode>(V);
3766 // Fill the Phi node with values from predecessors.
3767 for (auto *B : predecessors(PHI->getParent())) {
3768 Value *PV = cast<PHINode>(Current)->getIncomingValueForBlock(B);
3769 assert(Map.find(PV) != Map.end() && "No predecessor Value!")(static_cast <bool> (Map.find(PV) != Map.end() &&
"No predecessor Value!") ? void (0) : __assert_fail ("Map.find(PV) != Map.end() && \"No predecessor Value!\""
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 3769, __extension__ __PRETTY_FUNCTION__
))
;
3770 PHI->addIncoming(ST.Get(Map[PV]), B);
3771 }
3772 }
3773 Map[Current] = ST.Simplify(V);
3774 }
3775 }
3776
3777 /// Starting from original value recursively iterates over def-use chain up to
3778 /// known ending values represented in a map. For each traversed phi/select
3779 /// inserts a placeholder Phi or Select.
3780 /// Reports all new created Phi/Select nodes by adding them to set.
3781 /// Also reports and order in what values have been traversed.
3782 void InsertPlaceholders(FoldAddrToValueMapping &Map,
3783 SmallVectorImpl<Value *> &TraverseOrder,
3784 SimplificationTracker &ST) {
3785 SmallVector<Value *, 32> Worklist;
3786 assert((isa<PHINode>(Original) || isa<SelectInst>(Original)) &&(static_cast <bool> ((isa<PHINode>(Original) || isa
<SelectInst>(Original)) && "Address must be a Phi or Select node"
) ? void (0) : __assert_fail ("(isa<PHINode>(Original) || isa<SelectInst>(Original)) && \"Address must be a Phi or Select node\""
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 3787, __extension__ __PRETTY_FUNCTION__
))
3787 "Address must be a Phi or Select node")(static_cast <bool> ((isa<PHINode>(Original) || isa
<SelectInst>(Original)) && "Address must be a Phi or Select node"
) ? void (0) : __assert_fail ("(isa<PHINode>(Original) || isa<SelectInst>(Original)) && \"Address must be a Phi or Select node\""
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 3787, __extension__ __PRETTY_FUNCTION__
))
;
3788 auto *Dummy = UndefValue::get(CommonType);
3789 Worklist.push_back(Original);
3790 while (!Worklist.empty()) {
3791 Value *Current = Worklist.pop_back_val();
3792 // if it is already visited or it is an ending value then skip it.
3793 if (Map.find(Current) != Map.end())
3794 continue;
3795 TraverseOrder.push_back(Current);
3796
3797 // CurrentValue must be a Phi node or select. All others must be covered
3798 // by anchors.
3799 if (SelectInst *CurrentSelect = dyn_cast<SelectInst>(Current)) {
3800 // Is it OK to get metadata from OrigSelect?!
3801 // Create a Select placeholder with dummy value.
3802 SelectInst *Select = SelectInst::Create(
3803 CurrentSelect->getCondition(), Dummy, Dummy,
3804 CurrentSelect->getName(), CurrentSelect, CurrentSelect);
3805 Map[Current] = Select;
3806 ST.insertNewSelect(Select);
3807 // We are interested in True and False values.
3808 Worklist.push_back(CurrentSelect->getTrueValue());
3809 Worklist.push_back(CurrentSelect->getFalseValue());
3810 } else {
3811 // It must be a Phi node then.
3812 PHINode *CurrentPhi = cast<PHINode>(Current);
3813 unsigned PredCount = CurrentPhi->getNumIncomingValues();
3814 PHINode *PHI =
3815 PHINode::Create(CommonType, PredCount, "sunk_phi", CurrentPhi);
3816 Map[Current] = PHI;
3817 ST.insertNewPhi(PHI);
3818 append_range(Worklist, CurrentPhi->incoming_values());
3819 }
3820 }
3821 }
3822
3823 bool addrModeCombiningAllowed() {
3824 if (DisableComplexAddrModes)
3825 return false;
3826 switch (DifferentField) {
3827 default:
3828 return false;
3829 case ExtAddrMode::BaseRegField:
3830 return AddrSinkCombineBaseReg;
3831 case ExtAddrMode::BaseGVField:
3832 return AddrSinkCombineBaseGV;
3833 case ExtAddrMode::BaseOffsField:
3834 return AddrSinkCombineBaseOffs;
3835 case ExtAddrMode::ScaledRegField:
3836 return AddrSinkCombineScaledReg;
3837 }
3838 }
3839};
3840} // end anonymous namespace
3841
3842/// Try adding ScaleReg*Scale to the current addressing mode.
3843/// Return true and update AddrMode if this addr mode is legal for the target,
3844/// false if not.
3845bool AddressingModeMatcher::matchScaledValue(Value *ScaleReg, int64_t Scale,
3846 unsigned Depth) {
3847 // If Scale is 1, then this is the same as adding ScaleReg to the addressing
3848 // mode. Just process that directly.
3849 if (Scale == 1)
3850 return matchAddr(ScaleReg, Depth);
3851
3852 // If the scale is 0, it takes nothing to add this.
3853 if (Scale == 0)
3854 return true;
3855
3856 // If we already have a scale of this value, we can add to it, otherwise, we
3857 // need an available scale field.
3858 if (AddrMode.Scale != 0 && AddrMode.ScaledReg != ScaleReg)
3859 return false;
3860
3861 ExtAddrMode TestAddrMode = AddrMode;
3862
3863 // Add scale to turn X*4+X*3 -> X*7. This could also do things like
3864 // [A+B + A*7] -> [B+A*8].
3865 TestAddrMode.Scale += Scale;
3866 TestAddrMode.ScaledReg = ScaleReg;
3867
3868 // If the new address isn't legal, bail out.
3869 if (!TLI.isLegalAddressingMode(DL, TestAddrMode, AccessTy, AddrSpace))
3870 return false;
3871
3872 // It was legal, so commit it.
3873 AddrMode = TestAddrMode;
3874
3875 // Okay, we decided that we can add ScaleReg+Scale to AddrMode. Check now
3876 // to see if ScaleReg is actually X+C. If so, we can turn this into adding
3877 // X*Scale + C*Scale to addr mode. If we found available IV increment, do not
3878 // go any further: we can reuse it and cannot eliminate it.
3879 ConstantInt *CI = nullptr; Value *AddLHS = nullptr;
3880 if (isa<Instruction>(ScaleReg) && // not a constant expr.
3881 match(ScaleReg, m_Add(m_Value(AddLHS), m_ConstantInt(CI))) &&
3882 !isIVIncrement(ScaleReg, &LI) && CI->getValue().isSignedIntN(64)) {
3883 TestAddrMode.InBounds = false;
3884 TestAddrMode.ScaledReg = AddLHS;
3885 TestAddrMode.BaseOffs += CI->getSExtValue() * TestAddrMode.Scale;
3886
3887 // If this addressing mode is legal, commit it and remember that we folded
3888 // this instruction.
3889 if (TLI.isLegalAddressingMode(DL, TestAddrMode, AccessTy, AddrSpace)) {
3890 AddrModeInsts.push_back(cast<Instruction>(ScaleReg));
3891 AddrMode = TestAddrMode;
3892 return true;
3893 }
3894 // Restore status quo.
3895 TestAddrMode = AddrMode;
3896 }
3897
3898 // If this is an add recurrence with a constant step, return the increment
3899 // instruction and the canonicalized step.
3900 auto GetConstantStep = [this](const Value * V)
3901 ->Optional<std::pair<Instruction *, APInt> > {
3902 auto *PN = dyn_cast<PHINode>(V);
3903 if (!PN)
3904 return None;
3905 auto IVInc = getIVIncrement(PN, &LI);
3906 if (!IVInc)
3907 return None;
3908 // TODO: The result of the intrinsics above is two-compliment. However when
3909 // IV inc is expressed as add or sub, iv.next is potentially a poison value.
3910 // If it has nuw or nsw flags, we need to make sure that these flags are
3911 // inferrable at the point of memory instruction. Otherwise we are replacing
3912 // well-defined two-compliment computation with poison. Currently, to avoid
3913 // potentially complex analysis needed to prove this, we reject such cases.
3914 if (auto *OIVInc = dyn_cast<OverflowingBinaryOperator>(IVInc->first))
3915 if (OIVInc->hasNoSignedWrap() || OIVInc->hasNoUnsignedWrap())
3916 return None;
3917 if (auto *ConstantStep = dyn_cast<ConstantInt>(IVInc->second))
3918 return std::make_pair(IVInc->first, ConstantStep->getValue());
3919 return None;
3920 };
3921
3922 // Try to account for the following special case:
3923 // 1. ScaleReg is an inductive variable;
3924 // 2. We use it with non-zero offset;
3925 // 3. IV's increment is available at the point of memory instruction.
3926 //
3927 // In this case, we may reuse the IV increment instead of the IV Phi to
3928 // achieve the following advantages:
3929 // 1. If IV step matches the offset, we will have no need in the offset;
3930 // 2. Even if they don't match, we will reduce the overlap of living IV
3931 // and IV increment, that will potentially lead to better register
3932 // assignment.
3933 if (AddrMode.BaseOffs) {
3934 if (auto IVStep = GetConstantStep(ScaleReg)) {
3935 Instruction *IVInc = IVStep->first;
3936 // The following assert is important to ensure a lack of infinite loops.
3937 // This transforms is (intentionally) the inverse of the one just above.
3938 // If they don't agree on the definition of an increment, we'd alternate
3939 // back and forth indefinitely.
3940 assert(isIVIncrement(IVInc, &LI) && "implied by GetConstantStep")(static_cast <bool> (isIVIncrement(IVInc, &LI) &&
"implied by GetConstantStep") ? void (0) : __assert_fail ("isIVIncrement(IVInc, &LI) && \"implied by GetConstantStep\""
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 3940, __extension__ __PRETTY_FUNCTION__
))
;
3941 APInt Step = IVStep->second;
3942 APInt Offset = Step * AddrMode.Scale;
3943 if (Offset.isSignedIntN(64)) {
3944 TestAddrMode.InBounds = false;
3945 TestAddrMode.ScaledReg = IVInc;
3946 TestAddrMode.BaseOffs -= Offset.getLimitedValue();
3947 // If this addressing mode is legal, commit it..
3948 // (Note that we defer the (expensive) domtree base legality check
3949 // to the very last possible point.)
3950 if (TLI.isLegalAddressingMode(DL, TestAddrMode, AccessTy, AddrSpace) &&
3951 getDTFn().dominates(IVInc, MemoryInst)) {
3952 AddrModeInsts.push_back(cast<Instruction>(IVInc));
3953 AddrMode = TestAddrMode;
3954 return true;
3955 }
3956 // Restore status quo.
3957 TestAddrMode = AddrMode;
3958 }
3959 }
3960 }
3961
3962 // Otherwise, just return what we have.
3963 return true;
3964}
3965
3966/// This is a little filter, which returns true if an addressing computation
3967/// involving I might be folded into a load/store accessing it.
3968/// This doesn't need to be perfect, but needs to accept at least
3969/// the set of instructions that MatchOperationAddr can.
3970static bool MightBeFoldableInst(Instruction *I) {
3971 switch (I->getOpcode()) {
3972 case Instruction::BitCast:
3973 case Instruction::AddrSpaceCast:
3974 // Don't touch identity bitcasts.
3975 if (I->getType() == I->getOperand(0)->getType())
3976 return false;
3977 return I->getType()->isIntOrPtrTy();
3978 case Instruction::PtrToInt:
3979 // PtrToInt is always a noop, as we know that the int type is pointer sized.
3980 return true;
3981 case Instruction::IntToPtr:
3982 // We know the input is intptr_t, so this is foldable.
3983 return true;
3984 case Instruction::Add:
3985 return true;
3986 case Instruction::Mul:
3987 case Instruction::Shl:
3988 // Can only handle X*C and X << C.
3989 return isa<ConstantInt>(I->getOperand(1));
3990 case Instruction::GetElementPtr:
3991 return true;
3992 default:
3993 return false;
3994 }
3995}
3996
3997/// Check whether or not \p Val is a legal instruction for \p TLI.
3998/// \note \p Val is assumed to be the product of some type promotion.
3999/// Therefore if \p Val has an undefined state in \p TLI, this is assumed
4000/// to be legal, as the non-promoted value would have had the same state.
4001static bool isPromotedInstructionLegal(const TargetLowering &TLI,
4002 const DataLayout &DL, Value *Val) {
4003 Instruction *PromotedInst = dyn_cast<Instruction>(Val);
4004 if (!PromotedInst)
4005 return false;
4006 int ISDOpcode = TLI.InstructionOpcodeToISD(PromotedInst->getOpcode());
4007 // If the ISDOpcode is undefined, it was undefined before the promotion.
4008 if (!ISDOpcode)
4009 return true;
4010 // Otherwise, check if the promoted instruction is legal or not.
4011 return TLI.isOperationLegalOrCustom(
4012 ISDOpcode, TLI.getValueType(DL, PromotedInst->getType()));
4013}
4014
4015namespace {
4016
4017/// Hepler class to perform type promotion.
4018class TypePromotionHelper {
4019 /// Utility function to add a promoted instruction \p ExtOpnd to
4020 /// \p PromotedInsts and record the type of extension we have seen.
4021 static void addPromotedInst(InstrToOrigTy &PromotedInsts,
4022 Instruction *ExtOpnd,
4023 bool IsSExt) {
4024 ExtType ExtTy = IsSExt ? SignExtension : ZeroExtension;
4025 InstrToOrigTy::iterator It = PromotedInsts.find(ExtOpnd);
4026 if (It != PromotedInsts.end()) {
4027 // If the new extension is same as original, the information in
4028 // PromotedInsts[ExtOpnd] is still correct.
4029 if (It->second.getInt() == ExtTy)
4030 return;
4031
4032 // Now the new extension is different from old extension, we make
4033 // the type information invalid by setting extension type to
4034 // BothExtension.
4035 ExtTy = BothExtension;
4036 }
4037 PromotedInsts[ExtOpnd] = TypeIsSExt(ExtOpnd->getType(), ExtTy);
4038 }
4039
4040 /// Utility function to query the original type of instruction \p Opnd
4041 /// with a matched extension type. If the extension doesn't match, we
4042 /// cannot use the information we had on the original type.
4043 /// BothExtension doesn't match any extension type.
4044 static const Type *getOrigType(const InstrToOrigTy &PromotedInsts,
4045 Instruction *Opnd,
4046 bool IsSExt) {
4047 ExtType ExtTy = IsSExt ? SignExtension : ZeroExtension;
4048 InstrToOrigTy::const_iterator It = PromotedInsts.find(Opnd);
4049 if (It != PromotedInsts.end() && It->second.getInt() == ExtTy)
4050 return It->second.getPointer();
4051 return nullptr;
4052 }
4053
4054 /// Utility function to check whether or not a sign or zero extension
4055 /// of \p Inst with \p ConsideredExtType can be moved through \p Inst by
4056 /// either using the operands of \p Inst or promoting \p Inst.
4057 /// The type of the extension is defined by \p IsSExt.
4058 /// In other words, check if:
4059 /// ext (Ty Inst opnd1 opnd2 ... opndN) to ConsideredExtType.
4060 /// #1 Promotion applies:
4061 /// ConsideredExtType Inst (ext opnd1 to ConsideredExtType, ...).
4062 /// #2 Operand reuses:
4063 /// ext opnd1 to ConsideredExtType.
4064 /// \p PromotedInsts maps the instructions to their type before promotion.
4065 static bool canGetThrough(const Instruction *Inst, Type *ConsideredExtType,
4066 const InstrToOrigTy &PromotedInsts, bool IsSExt);
4067
4068 /// Utility function to determine if \p OpIdx should be promoted when
4069 /// promoting \p Inst.
4070 static bool shouldExtOperand(const Instruction *Inst, int OpIdx) {
4071 return !(isa<SelectInst>(Inst) && OpIdx == 0);
4072 }
4073
4074 /// Utility function to promote the operand of \p Ext when this
4075 /// operand is a promotable trunc or sext or zext.
4076 /// \p PromotedInsts maps the instructions to their type before promotion.
4077 /// \p CreatedInstsCost[out] contains the cost of all instructions
4078 /// created to promote the operand of Ext.
4079 /// Newly added extensions are inserted in \p Exts.
4080 /// Newly added truncates are inserted in \p Truncs.
4081 /// Should never be called directly.
4082 /// \return The promoted value which is used instead of Ext.
4083 static Value *promoteOperandForTruncAndAnyExt(
4084 Instruction *Ext, TypePromotionTransaction &TPT,
4085 InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
4086 SmallVectorImpl<Instruction *> *Exts,
4087 SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI);
4088
4089 /// Utility function to promote the operand of \p Ext when this
4090 /// operand is promotable and is not a supported trunc or sext.
4091 /// \p PromotedInsts maps the instructions to their type before promotion.
4092 /// \p CreatedInstsCost[out] contains the cost of all the instructions
4093 /// created to promote the operand of Ext.
4094 /// Newly added extensions are inserted in \p Exts.
4095 /// Newly added truncates are inserted in \p Truncs.
4096 /// Should never be called directly.
4097 /// \return The promoted value which is used instead of Ext.
4098 static Value *promoteOperandForOther(Instruction *Ext,
4099 TypePromotionTransaction &TPT,
4100 InstrToOrigTy &PromotedInsts,
4101 unsigned &CreatedInstsCost,
4102 SmallVectorImpl<Instruction *> *Exts,
4103 SmallVectorImpl<Instruction *> *Truncs,
4104 const TargetLowering &TLI, bool IsSExt);
4105
4106 /// \see promoteOperandForOther.
4107 static Value *signExtendOperandForOther(
4108 Instruction *Ext, TypePromotionTransaction &TPT,
4109 InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
4110 SmallVectorImpl<Instruction *> *Exts,
4111 SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI) {
4112 return promoteOperandForOther(Ext, TPT, PromotedInsts, CreatedInstsCost,
4113 Exts, Truncs, TLI, true);
4114 }
4115
4116 /// \see promoteOperandForOther.
4117 static Value *zeroExtendOperandForOther(
4118 Instruction *Ext, TypePromotionTransaction &TPT,
4119 InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
4120 SmallVectorImpl<Instruction *> *Exts,
4121 SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI) {
4122 return promoteOperandForOther(Ext, TPT, PromotedInsts, CreatedInstsCost,
4123 Exts, Truncs, TLI, false);
4124 }
4125
4126public:
4127 /// Type for the utility function that promotes the operand of Ext.
4128 using Action = Value *(*)(Instruction *Ext, TypePromotionTransaction &TPT,
4129 InstrToOrigTy &PromotedInsts,
4130 unsigned &CreatedInstsCost,
4131 SmallVectorImpl<Instruction *> *Exts,
4132 SmallVectorImpl<Instruction *> *Truncs,
4133 const TargetLowering &TLI);
4134
4135 /// Given a sign/zero extend instruction \p Ext, return the appropriate
4136 /// action to promote the operand of \p Ext instead of using Ext.
4137 /// \return NULL if no promotable action is possible with the current
4138 /// sign extension.
4139 /// \p InsertedInsts keeps track of all the instructions inserted by the
4140 /// other CodeGenPrepare optimizations. This information is important
4141 /// because we do not want to promote these instructions as CodeGenPrepare
4142 /// will reinsert them later. Thus creating an infinite loop: create/remove.
4143 /// \p PromotedInsts maps the instructions to their type before promotion.
4144 static Action getAction(Instruction *Ext, const SetOfInstrs &InsertedInsts,
4145 const TargetLowering &TLI,
4146 const InstrToOrigTy &PromotedInsts);
4147};
4148
4149} // end anonymous namespace
4150
4151bool TypePromotionHelper::canGetThrough(const Instruction *Inst,
4152 Type *ConsideredExtType,
4153 const InstrToOrigTy &PromotedInsts,
4154 bool IsSExt) {
4155 // The promotion helper does not know how to deal with vector types yet.
4156 // To be able to fix that, we would need to fix the places where we
4157 // statically extend, e.g., constants and such.
4158 if (Inst->getType()->isVectorTy())
15
Calling 'Type::isVectorTy'
19
Returning from 'Type::isVectorTy'
20
Taking false branch
4159 return false;
4160
4161 // We can always get through zext.
4162 if (isa<ZExtInst>(Inst))
21
Assuming 'Inst' is not a 'ZExtInst'
4163 return true;
4164
4165 // sext(sext) is ok too.
4166 if (IsSExt
21.1
'IsSExt' is false
21.1
'IsSExt' is false
&& isa<SExtInst>(Inst))
4167 return true;
4168
4169 // We can get through binary operator, if it is legal. In other words, the
4170 // binary operator must have a nuw or nsw flag.
4171 const BinaryOperator *BinOp = dyn_cast<BinaryOperator>(Inst);
22
Assuming 'Inst' is not a 'BinaryOperator'
23
'BinOp' initialized to a null pointer value
4172 if (isa_and_nonnull<OverflowingBinaryOperator>(BinOp) &&
24
Assuming 'BinOp' is a 'OverflowingBinaryOperator'
4173 ((!IsSExt
24.1
'IsSExt' is false
24.1
'IsSExt' is false
&& BinOp->hasNoUnsignedWrap()) ||
25
Called C++ object pointer is null
4174 (IsSExt && BinOp->hasNoSignedWrap())))
4175 return true;
4176
4177 // ext(and(opnd, cst)) --> and(ext(opnd), ext(cst))
4178 if ((Inst->getOpcode() == Instruction::And ||
4179 Inst->getOpcode() == Instruction::Or))
4180 return true;
4181
4182 // ext(xor(opnd, cst)) --> xor(ext(opnd), ext(cst))
4183 if (Inst->getOpcode() == Instruction::Xor) {
4184 const ConstantInt *Cst = dyn_cast<ConstantInt>(Inst->getOperand(1));
4185 // Make sure it is not a NOT.
4186 if (Cst && !Cst->getValue().isAllOnes())
4187 return true;
4188 }
4189
4190 // zext(shrl(opnd, cst)) --> shrl(zext(opnd), zext(cst))
4191 // It may change a poisoned value into a regular value, like
4192 // zext i32 (shrl i8 %val, 12) --> shrl i32 (zext i8 %val), 12
4193 // poisoned value regular value
4194 // It should be OK since undef covers valid value.
4195 if (Inst->getOpcode() == Instruction::LShr && !IsSExt)
4196 return true;
4197
4198 // and(ext(shl(opnd, cst)), cst) --> and(shl(ext(opnd), ext(cst)), cst)
4199 // It may change a poisoned value into a regular value, like
4200 // zext i32 (shl i8 %val, 12) --> shl i32 (zext i8 %val), 12
4201 // poisoned value regular value
4202 // It should be OK since undef covers valid value.
4203 if (Inst->getOpcode() == Instruction::Shl && Inst->hasOneUse()) {
4204 const auto *ExtInst = cast<const Instruction>(*Inst->user_begin());
4205 if (ExtInst->hasOneUse()) {
4206 const auto *AndInst = dyn_cast<const Instruction>(*ExtInst->user_begin());
4207 if (AndInst && AndInst->getOpcode() == Instruction::And) {
4208 const auto *Cst = dyn_cast<ConstantInt>(AndInst->getOperand(1));
4209 if (Cst &&
4210 Cst->getValue().isIntN(Inst->getType()->getIntegerBitWidth()))
4211 return true;
4212 }
4213 }
4214 }
4215
4216 // Check if we can do the following simplification.
4217 // ext(trunc(opnd)) --> ext(opnd)
4218 if (!isa<TruncInst>(Inst))
4219 return false;
4220
4221 Value *OpndVal = Inst->getOperand(0);
4222 // Check if we can use this operand in the extension.
4223 // If the type is larger than the result type of the extension, we cannot.
4224 if (!OpndVal->getType()->isIntegerTy() ||
4225 OpndVal->getType()->getIntegerBitWidth() >
4226 ConsideredExtType->getIntegerBitWidth())
4227 return false;
4228
4229 // If the operand of the truncate is not an instruction, we will not have
4230 // any information on the dropped bits.
4231 // (Actually we could for constant but it is not worth the extra logic).
4232 Instruction *Opnd = dyn_cast<Instruction>(OpndVal);
4233 if (!Opnd)
4234 return false;
4235
4236 // Check if the source of the type is narrow enough.
4237 // I.e., check that trunc just drops extended bits of the same kind of
4238 // the extension.
4239 // #1 get the type of the operand and check the kind of the extended bits.
4240 const Type *OpndType = getOrigType(PromotedInsts, Opnd, IsSExt);
4241 if (OpndType)
4242 ;
4243 else if ((IsSExt && isa<SExtInst>(Opnd)) || (!IsSExt && isa<ZExtInst>(Opnd)))
4244 OpndType = Opnd->getOperand(0)->getType();
4245 else
4246 return false;
4247
4248 // #2 check that the truncate just drops extended bits.
4249 return Inst->getType()->getIntegerBitWidth() >=
4250 OpndType->getIntegerBitWidth();
4251}
4252
4253TypePromotionHelper::Action TypePromotionHelper::getAction(
4254 Instruction *Ext, const SetOfInstrs &InsertedInsts,
4255 const TargetLowering &TLI, const InstrToOrigTy &PromotedInsts) {
4256 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\""
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 4257, __extension__ __PRETTY_FUNCTION__
))
9
Assuming 'Ext' is not a 'SExtInst'
10
Assuming 'Ext' is a 'ZExtInst'
11
'?' condition is true
4257 "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\""
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 4257, __extension__ __PRETTY_FUNCTION__
))
;
4258 Instruction *ExtOpnd = dyn_cast<Instruction>(Ext->getOperand(0));
12
Assuming the object is a 'Instruction'
4259 Type *ExtTy = Ext->getType();
4260 bool IsSExt = isa<SExtInst>(Ext);
13
Assuming 'Ext' is not a 'SExtInst'
4261 // If the operand of the extension is not an instruction, we cannot
4262 // get through.
4263 // If it, check we can get through.
4264 if (!ExtOpnd
13.1
'ExtOpnd' is non-null
13.1
'ExtOpnd' is non-null
|| !canGetThrough(ExtOpnd, ExtTy, PromotedInsts, IsSExt))
14
Calling 'TypePromotionHelper::canGetThrough'
4265 return nullptr;
4266
4267 // Do not promote if the operand has been added by codegenprepare.
4268 // Otherwise, it means we are undoing an optimization that is likely to be
4269 // redone, thus causing potential infinite loop.
4270 if (isa<TruncInst>(ExtOpnd) && InsertedInsts.count(ExtOpnd))
4271 return nullptr;
4272
4273 // SExt or Trunc instructions.
4274 // Return the related handler.
4275 if (isa<SExtInst>(ExtOpnd) || isa<TruncInst>(ExtOpnd) ||
4276 isa<ZExtInst>(ExtOpnd))
4277 return promoteOperandForTruncAndAnyExt;
4278
4279 // Regular instruction.
4280 // Abort early if we will have to insert non-free instructions.
4281 if (!ExtOpnd->hasOneUse() && !TLI.isTruncateFree(ExtTy, ExtOpnd->getType()))
4282 return nullptr;
4283 return IsSExt ? signExtendOperandForOther : zeroExtendOperandForOther;
4284}
4285
4286Value *TypePromotionHelper::promoteOperandForTruncAndAnyExt(
4287 Instruction *SExt, TypePromotionTransaction &TPT,
4288 InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
4289 SmallVectorImpl<Instruction *> *Exts,
4290 SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI) {
4291 // By construction, the operand of SExt is an instruction. Otherwise we cannot
4292 // get through it and this method should not be called.
4293 Instruction *SExtOpnd = cast<Instruction>(SExt->getOperand(0));
4294 Value *ExtVal = SExt;
4295 bool HasMergedNonFreeExt = false;
4296 if (isa<ZExtInst>(SExtOpnd)) {
4297 // Replace s|zext(zext(opnd))
4298 // => zext(opnd).
4299 HasMergedNonFreeExt = !TLI.isExtFree(SExtOpnd);
4300 Value *ZExt =
4301 TPT.createZExt(SExt, SExtOpnd->getOperand(0), SExt->getType());
4302 TPT.replaceAllUsesWith(SExt, ZExt);
4303 TPT.eraseInstruction(SExt);
4304 ExtVal = ZExt;
4305 } else {
4306 // Replace z|sext(trunc(opnd)) or sext(sext(opnd))
4307 // => z|sext(opnd).
4308 TPT.setOperand(SExt, 0, SExtOpnd->getOperand(0));
4309 }
4310 CreatedInstsCost = 0;
4311
4312 // Remove dead code.
4313 if (SExtOpnd->use_empty())
4314 TPT.eraseInstruction(SExtOpnd);
4315
4316 // Check if the extension is still needed.
4317 Instruction *ExtInst = dyn_cast<Instruction>(ExtVal);
4318 if (!ExtInst || ExtInst->getType() != ExtInst->getOperand(0)->getType()) {
4319 if (ExtInst) {
4320 if (Exts)
4321 Exts->push_back(ExtInst);
4322 CreatedInstsCost = !TLI.isExtFree(ExtInst) && !HasMergedNonFreeExt;
4323 }
4324 return ExtVal;
4325 }
4326
4327 // At this point we have: ext ty opnd to ty.
4328 // Reassign the uses of ExtInst to the opnd and remove ExtInst.
4329 Value *NextVal = ExtInst->getOperand(0);
4330 TPT.eraseInstruction(ExtInst, NextVal);
4331 return NextVal;
4332}
4333
4334Value *TypePromotionHelper::promoteOperandForOther(
4335 Instruction *Ext, TypePromotionTransaction &TPT,
4336 InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
4337 SmallVectorImpl<Instruction *> *Exts,
4338 SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI,
4339 bool IsSExt) {
4340 // By construction, the operand of Ext is an instruction. Otherwise we cannot
4341 // get through it and this method should not be called.
4342 Instruction *ExtOpnd = cast<Instruction>(Ext->getOperand(0));
4343 CreatedInstsCost = 0;
4344 if (!ExtOpnd->hasOneUse()) {
4345 // ExtOpnd will be promoted.
4346 // All its uses, but Ext, will need to use a truncated value of the
4347 // promoted version.
4348 // Create the truncate now.
4349 Value *Trunc = TPT.createTrunc(Ext, ExtOpnd->getType());
4350 if (Instruction *ITrunc = dyn_cast<Instruction>(Trunc)) {
4351 // Insert it just after the definition.
4352 ITrunc->moveAfter(ExtOpnd);
4353 if (Truncs)
4354 Truncs->push_back(ITrunc);
4355 }
4356
4357 TPT.replaceAllUsesWith(ExtOpnd, Trunc);
4358 // Restore the operand of Ext (which has been replaced by the previous call
4359 // to replaceAllUsesWith) to avoid creating a cycle trunc <-> sext.
4360 TPT.setOperand(Ext, 0, ExtOpnd);
4361 }
4362
4363 // Get through the Instruction:
4364 // 1. Update its type.
4365 // 2. Replace the uses of Ext by Inst.
4366 // 3. Extend each operand that needs to be extended.
4367
4368 // Remember the original type of the instruction before promotion.
4369 // This is useful to know that the high bits are sign extended bits.
4370 addPromotedInst(PromotedInsts, ExtOpnd, IsSExt);
4371 // Step #1.
4372 TPT.mutateType(ExtOpnd, Ext->getType());
4373 // Step #2.
4374 TPT.replaceAllUsesWith(Ext, ExtOpnd);
4375 // Step #3.
4376 Instruction *ExtForOpnd = Ext;
4377
4378 LLVM_DEBUG(dbgs() << "Propagate Ext to operands\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Propagate Ext to operands\n"
; } } while (false)
;
4379 for (int OpIdx = 0, EndOpIdx = ExtOpnd->getNumOperands(); OpIdx != EndOpIdx;
4380 ++OpIdx) {
4381 LLVM_DEBUG(dbgs() << "Operand:\n" << *(ExtOpnd->getOperand(OpIdx)) << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Operand:\n" << *
(ExtOpnd->getOperand(OpIdx)) << '\n'; } } while (false
)
;
4382 if (ExtOpnd->getOperand(OpIdx)->getType() == Ext->getType() ||
4383 !shouldExtOperand(ExtOpnd, OpIdx)) {
4384 LLVM_DEBUG(dbgs() << "No need to propagate\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "No need to propagate\n"
; } } while (false)
;
4385 continue;
4386 }
4387 // Check if we can statically extend the operand.
4388 Value *Opnd = ExtOpnd->getOperand(OpIdx);
4389 if (const ConstantInt *Cst = dyn_cast<ConstantInt>(Opnd)) {
4390 LLVM_DEBUG(dbgs() << "Statically extend\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Statically extend\n"; }
} while (false)
;
4391 unsigned BitWidth = Ext->getType()->getIntegerBitWidth();
4392 APInt CstVal = IsSExt ? Cst->getValue().sext(BitWidth)
4393 : Cst->getValue().zext(BitWidth);
4394 TPT.setOperand(ExtOpnd, OpIdx, ConstantInt::get(Ext->getType(), CstVal));
4395 continue;
4396 }
4397 // UndefValue are typed, so we have to statically sign extend them.
4398 if (isa<UndefValue>(Opnd)) {
4399 LLVM_DEBUG(dbgs() << "Statically extend\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Statically extend\n"; }
} while (false)
;
4400 TPT.setOperand(ExtOpnd, OpIdx, UndefValue::get(Ext->getType()));
4401 continue;
4402 }
4403
4404 // Otherwise we have to explicitly sign extend the operand.
4405 // Check if Ext was reused to extend an operand.
4406 if (!ExtForOpnd) {
4407 // If yes, create a new one.
4408 LLVM_DEBUG(dbgs() << "More operands to ext\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "More operands to ext\n"
; } } while (false)
;
4409 Value *ValForExtOpnd = IsSExt ? TPT.createSExt(Ext, Opnd, Ext->getType())
4410 : TPT.createZExt(Ext, Opnd, Ext->getType());
4411 if (!isa<Instruction>(ValForExtOpnd)) {
4412 TPT.setOperand(ExtOpnd, OpIdx, ValForExtOpnd);
4413 continue;
4414 }
4415 ExtForOpnd = cast<Instruction>(ValForExtOpnd);
4416 }
4417 if (Exts)
4418 Exts->push_back(ExtForOpnd);
4419 TPT.setOperand(ExtForOpnd, 0, Opnd);
4420
4421 // Move the sign extension before the insertion point.
4422 TPT.moveBefore(ExtForOpnd, ExtOpnd);
4423 TPT.setOperand(ExtOpnd, OpIdx, ExtForOpnd);
4424 CreatedInstsCost += !TLI.isExtFree(ExtForOpnd);
4425 // If more sext are required, new instructions will have to be created.
4426 ExtForOpnd = nullptr;
4427 }
4428 if (ExtForOpnd == Ext) {
4429 LLVM_DEBUG(dbgs() << "Extension is useless now\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Extension is useless now\n"
; } } while (false)
;
4430 TPT.eraseInstruction(Ext);
4431 }
4432 return ExtOpnd;
4433}
4434
4435/// Check whether or not promoting an instruction to a wider type is profitable.
4436/// \p NewCost gives the cost of extension instructions created by the
4437/// promotion.
4438/// \p OldCost gives the cost of extension instructions before the promotion
4439/// plus the number of instructions that have been
4440/// matched in the addressing mode the promotion.
4441/// \p PromotedOperand is the value that has been promoted.
4442/// \return True if the promotion is profitable, false otherwise.
4443bool AddressingModeMatcher::isPromotionProfitable(
4444 unsigned NewCost, unsigned OldCost, Value *PromotedOperand) const {
4445 LLVM_DEBUG(dbgs() << "OldCost: " << OldCost << "\tNewCost: " << NewCostdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "OldCost: " << OldCost
<< "\tNewCost: " << NewCost << '\n'; } } while
(false)
4446 << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "OldCost: " << OldCost
<< "\tNewCost: " << NewCost << '\n'; } } while
(false)
;
4447 // The cost of the new extensions is greater than the cost of the
4448 // old extension plus what we folded.
4449 // This is not profitable.
4450 if (NewCost > OldCost)
4451 return false;
4452 if (NewCost < OldCost)
4453 return true;
4454 // The promotion is neutral but it may help folding the sign extension in
4455 // loads for instance.
4456 // Check that we did not create an illegal instruction.
4457 return isPromotedInstructionLegal(TLI, DL, PromotedOperand);
4458}
4459
4460/// Given an instruction or constant expr, see if we can fold the operation
4461/// into the addressing mode. If so, update the addressing mode and return
4462/// true, otherwise return false without modifying AddrMode.
4463/// If \p MovedAway is not NULL, it contains the information of whether or
4464/// not AddrInst has to be folded into the addressing mode on success.
4465/// If \p MovedAway == true, \p AddrInst will not be part of the addressing
4466/// because it has been moved away.
4467/// Thus AddrInst must not be added in the matched instructions.
4468/// This state can happen when AddrInst is a sext, since it may be moved away.
4469/// Therefore, AddrInst may not be valid when MovedAway is true and it must
4470/// not be referenced anymore.
4471bool AddressingModeMatcher::matchOperationAddr(User *AddrInst, unsigned Opcode,
4472 unsigned Depth,
4473 bool *MovedAway) {
4474 // Avoid exponential behavior on extremely deep expression trees.
4475 if (Depth >= 5) return false;
1
Assuming 'Depth' is < 5
2
Taking false branch
4476
4477 // By default, all matched instructions stay in place.
4478 if (MovedAway)
3
Assuming 'MovedAway' is null
4
Taking false branch
4479 *MovedAway = false;
4480
4481 switch (Opcode) {
5
Control jumps to 'case ZExt:' at line 4681
4482 case Instruction::PtrToInt:
4483 // PtrToInt is always a noop, as we know that the int type is pointer sized.
4484 return matchAddr(AddrInst->getOperand(0), Depth);
4485 case Instruction::IntToPtr: {
4486 auto AS = AddrInst->getType()->getPointerAddressSpace();
4487 auto PtrTy = MVT::getIntegerVT(DL.getPointerSizeInBits(AS));
4488 // This inttoptr is a no-op if the integer type is pointer sized.
4489 if (TLI.getValueType(DL, AddrInst->getOperand(0)->getType()) == PtrTy)
4490 return matchAddr(AddrInst->getOperand(0), Depth);
4491 return false;
4492 }
4493 case Instruction::BitCast:
4494 // BitCast is always a noop, and we can handle it as long as it is
4495 // int->int or pointer->pointer (we don't want int<->fp or something).
4496 if (AddrInst->getOperand(0)->getType()->isIntOrPtrTy() &&
4497 // Don't touch identity bitcasts. These were probably put here by LSR,
4498 // and we don't want to mess around with them. Assume it knows what it
4499 // is doing.
4500 AddrInst->getOperand(0)->getType() != AddrInst->getType())
4501 return matchAddr(AddrInst->getOperand(0), Depth);
4502 return false;
4503 case Instruction::AddrSpaceCast: {
4504 unsigned SrcAS
4505 = AddrInst->getOperand(0)->getType()->getPointerAddressSpace();
4506 unsigned DestAS = AddrInst->getType()->getPointerAddressSpace();
4507 if (TLI.getTargetMachine().isNoopAddrSpaceCast(SrcAS, DestAS))
4508 return matchAddr(AddrInst->getOperand(0), Depth);
4509 return false;
4510 }
4511 case Instruction::Add: {
4512 // Check to see if we can merge in the RHS then the LHS. If so, we win.
4513 ExtAddrMode BackupAddrMode = AddrMode;
4514 unsigned OldSize = AddrModeInsts.size();
4515 // Start a transaction at this point.
4516 // The LHS may match but not the RHS.
4517 // Therefore, we need a higher level restoration point to undo partially
4518 // matched operation.
4519 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
4520 TPT.getRestorationPoint();
4521
4522 AddrMode.InBounds = false;
4523 if (matchAddr(AddrInst->getOperand(1), Depth+1) &&
4524 matchAddr(AddrInst->getOperand(0), Depth+1))
4525 return true;
4526
4527 // Restore the old addr mode info.
4528 AddrMode = BackupAddrMode;
4529 AddrModeInsts.resize(OldSize);
4530 TPT.rollback(LastKnownGood);
4531
4532 // Otherwise this was over-aggressive. Try merging in the LHS then the RHS.
4533 if (matchAddr(AddrInst->getOperand(0), Depth+1) &&
4534 matchAddr(AddrInst->getOperand(1), Depth+1))
4535 return true;
4536
4537 // Otherwise we definitely can't merge the ADD in.
4538 AddrMode = BackupAddrMode;
4539 AddrModeInsts.resize(OldSize);
4540 TPT.rollback(LastKnownGood);
4541 break;
4542 }
4543 //case Instruction::Or:
4544 // TODO: We can handle "Or Val, Imm" iff this OR is equivalent to an ADD.
4545 //break;
4546 case Instruction::Mul:
4547 case Instruction::Shl: {
4548 // Can only handle X*C and X << C.
4549 AddrMode.InBounds = false;
4550 ConstantInt *RHS = dyn_cast<ConstantInt>(AddrInst->getOperand(1));
4551 if (!RHS || RHS->getBitWidth() > 64)
4552 return false;
4553 int64_t Scale = RHS->getSExtValue();
4554 if (Opcode == Instruction::Shl)
4555 Scale = 1LL << Scale;
4556
4557 return matchScaledValue(AddrInst->getOperand(0), Scale, Depth);
4558 }
4559 case Instruction::GetElementPtr: {
4560 // Scan the GEP. We check it if it contains constant offsets and at most
4561 // one variable offset.
4562 int VariableOperand = -1;
4563 unsigned VariableScale = 0;
4564
4565 int64_t ConstantOffset = 0;
4566 gep_type_iterator GTI = gep_type_begin(AddrInst);
4567 for (unsigned i = 1, e = AddrInst->getNumOperands(); i != e; ++i, ++GTI) {
4568 if (StructType *STy = GTI.getStructTypeOrNull()) {
4569 const StructLayout *SL = DL.getStructLayout(STy);
4570 unsigned Idx =
4571 cast<ConstantInt>(AddrInst->getOperand(i))->getZExtValue();
4572 ConstantOffset += SL->getElementOffset(Idx);
4573 } else {
4574 TypeSize TS = DL.getTypeAllocSize(GTI.getIndexedType());
4575 if (TS.isNonZero()) {
4576 // The optimisations below currently only work for fixed offsets.
4577 if (TS.isScalable())
4578 return false;
4579 int64_t TypeSize = TS.getFixedSize();
4580 if (ConstantInt *CI =
4581 dyn_cast<ConstantInt>(AddrInst->getOperand(i))) {
4582 const APInt &CVal = CI->getValue();
4583 if (CVal.getMinSignedBits() <= 64) {
4584 ConstantOffset += CVal.getSExtValue() * TypeSize;
4585 continue;
4586 }
4587 }
4588 // We only allow one variable index at the moment.
4589 if (VariableOperand != -1)
4590 return false;
4591
4592 // Remember the variable index.
4593 VariableOperand = i;
4594 VariableScale = TypeSize;
4595 }
4596 }
4597 }
4598
4599 // A common case is for the GEP to only do a constant offset. In this case,
4600 // just add it to the disp field and check validity.
4601 if (VariableOperand == -1) {
4602 AddrMode.BaseOffs += ConstantOffset;
4603 if (ConstantOffset == 0 ||
4604 TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace)) {
4605 // Check to see if we can fold the base pointer in too.
4606 if (matchAddr(AddrInst->getOperand(0), Depth+1)) {
4607 if (!cast<GEPOperator>(AddrInst)->isInBounds())
4608 AddrMode.InBounds = false;
4609 return true;
4610 }
4611 } else if (EnableGEPOffsetSplit && isa<GetElementPtrInst>(AddrInst) &&
4612 TLI.shouldConsiderGEPOffsetSplit() && Depth == 0 &&
4613 ConstantOffset > 0) {
4614 // Record GEPs with non-zero offsets as candidates for splitting in the
4615 // event that the offset cannot fit into the r+i addressing mode.
4616 // Simple and common case that only one GEP is used in calculating the
4617 // address for the memory access.
4618 Value *Base = AddrInst->getOperand(0);
4619 auto *BaseI = dyn_cast<Instruction>(Base);
4620 auto *GEP = cast<GetElementPtrInst>(AddrInst);
4621 if (isa<Argument>(Base) || isa<GlobalValue>(Base) ||
4622 (BaseI && !isa<CastInst>(BaseI) &&
4623 !isa<GetElementPtrInst>(BaseI))) {
4624 // Make sure the parent block allows inserting non-PHI instructions
4625 // before the terminator.
4626 BasicBlock *Parent =
4627 BaseI ? BaseI->getParent() : &GEP->getFunction()->getEntryBlock();
4628 if (!Parent->getTerminator()->isEHPad())
4629 LargeOffsetGEP = std::make_pair(GEP, ConstantOffset);
4630 }
4631 }
4632 AddrMode.BaseOffs -= ConstantOffset;
4633 return false;
4634 }
4635
4636 // Save the valid addressing mode in case we can't match.
4637 ExtAddrMode BackupAddrMode = AddrMode;
4638 unsigned OldSize = AddrModeInsts.size();
4639
4640 // See if the scale and offset amount is valid for this target.
4641 AddrMode.BaseOffs += ConstantOffset;
4642 if (!cast<GEPOperator>(AddrInst)->isInBounds())
4643 AddrMode.InBounds = false;
4644
4645 // Match the base operand of the GEP.
4646 if (!matchAddr(AddrInst->getOperand(0), Depth+1)) {
4647 // If it couldn't be matched, just stuff the value in a register.
4648 if (AddrMode.HasBaseReg) {
4649 AddrMode = BackupAddrMode;
4650 AddrModeInsts.resize(OldSize);
4651 return false;
4652 }
4653 AddrMode.HasBaseReg = true;
4654 AddrMode.BaseReg = AddrInst->getOperand(0);
4655 }
4656
4657 // Match the remaining variable portion of the GEP.
4658 if (!matchScaledValue(AddrInst->getOperand(VariableOperand), VariableScale,
4659 Depth)) {
4660 // If it couldn't be matched, try stuffing the base into a register
4661 // instead of matching it, and retrying the match of the scale.
4662 AddrMode = BackupAddrMode;
4663 AddrModeInsts.resize(OldSize);
4664 if (AddrMode.HasBaseReg)
4665 return false;
4666 AddrMode.HasBaseReg = true;
4667 AddrMode.BaseReg = AddrInst->getOperand(0);
4668 AddrMode.BaseOffs += ConstantOffset;
4669 if (!matchScaledValue(AddrInst->getOperand(VariableOperand),
4670 VariableScale, Depth)) {
4671 // If even that didn't work, bail.
4672 AddrMode = BackupAddrMode;
4673 AddrModeInsts.resize(OldSize);
4674 return false;
4675 }
4676 }
4677
4678 return true;
4679 }
4680 case Instruction::SExt:
4681 case Instruction::ZExt: {
4682 Instruction *Ext = dyn_cast<Instruction>(AddrInst);
6
Assuming 'AddrInst' is a 'Instruction'
4683 if (!Ext
6.1
'Ext' is non-null
6.1
'Ext' is non-null
)
7
Taking false branch
4684 return false;
4685
4686 // Try to move this ext out of the way of the addressing mode.
4687 // Ask for a method for doing so.
4688 TypePromotionHelper::Action TPH =
4689 TypePromotionHelper::getAction(Ext, InsertedInsts, TLI, PromotedInsts);
8
Calling 'TypePromotionHelper::getAction'
4690 if (!TPH)
4691 return false;
4692
4693 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
4694 TPT.getRestorationPoint();
4695 unsigned CreatedInstsCost = 0;
4696 unsigned ExtCost = !TLI.isExtFree(Ext);
4697 Value *PromotedOperand =
4698 TPH(Ext, TPT, PromotedInsts, CreatedInstsCost, nullptr, nullptr, TLI);
4699 // SExt has been moved away.
4700 // Thus either it will be rematched later in the recursive calls or it is
4701 // gone. Anyway, we must not fold it into the addressing mode at this point.
4702 // E.g.,
4703 // op = add opnd, 1
4704 // idx = ext op
4705 // addr = gep base, idx
4706 // is now:
4707 // promotedOpnd = ext opnd <- no match here
4708 // op = promoted_add promotedOpnd, 1 <- match (later in recursive calls)
4709 // addr = gep base, op <- match
4710 if (MovedAway)
4711 *MovedAway = true;
4712
4713 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\""
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 4714, __extension__ __PRETTY_FUNCTION__
))
4714 "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\""
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 4714, __extension__ __PRETTY_FUNCTION__
))
;
4715
4716 ExtAddrMode BackupAddrMode = AddrMode;
4717 unsigned OldSize = AddrModeInsts.size();
4718
4719 if (!matchAddr(PromotedOperand, Depth) ||
4720 // The total of the new cost is equal to the cost of the created
4721 // instructions.
4722 // The total of the old cost is equal to the cost of the extension plus
4723 // what we have saved in the addressing mode.
4724 !isPromotionProfitable(CreatedInstsCost,
4725 ExtCost + (AddrModeInsts.size() - OldSize),
4726 PromotedOperand)) {
4727 AddrMode = BackupAddrMode;
4728 AddrModeInsts.resize(OldSize);
4729 LLVM_DEBUG(dbgs() << "Sign extension does not pay off: rollback\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Sign extension does not pay off: rollback\n"
; } } while (false)
;
4730 TPT.rollback(LastKnownGood);
4731 return false;
4732 }
4733 return true;
4734 }
4735 }
4736 return false;
4737}
4738
4739/// If we can, try to add the value of 'Addr' into the current addressing mode.
4740/// If Addr can't be added to AddrMode this returns false and leaves AddrMode
4741/// unmodified. This assumes that Addr is either a pointer type or intptr_t
4742/// for the target.
4743///
4744bool AddressingModeMatcher::matchAddr(Value *Addr, unsigned Depth) {
4745 // Start a transaction at this point that we will rollback if the matching
4746 // fails.
4747 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
4748 TPT.getRestorationPoint();
4749 if (ConstantInt *CI = dyn_cast<ConstantInt>(Addr)) {
4750 if (CI->getValue().isSignedIntN(64)) {
4751 // Fold in immediates if legal for the target.
4752 AddrMode.BaseOffs += CI->getSExtValue();
4753 if (TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace))
4754 return true;
4755 AddrMode.BaseOffs -= CI->getSExtValue();
4756 }
4757 } else if (GlobalValue *GV = dyn_cast<GlobalValue>(Addr)) {
4758 // If this is a global variable, try to fold it into the addressing mode.
4759 if (!AddrMode.BaseGV) {
4760 AddrMode.BaseGV = GV;
4761 if (TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace))
4762 return true;
4763 AddrMode.BaseGV = nullptr;
4764 }
4765 } else if (Instruction *I = dyn_cast<Instruction>(Addr)) {
4766 ExtAddrMode BackupAddrMode = AddrMode;
4767 unsigned OldSize = AddrModeInsts.size();
4768
4769 // Check to see if it is possible to fold this operation.
4770 bool MovedAway = false;
4771 if (matchOperationAddr(I, I->getOpcode(), Depth, &MovedAway)) {
4772 // This instruction may have been moved away. If so, there is nothing
4773 // to check here.
4774 if (MovedAway)
4775 return true;
4776 // Okay, it's possible to fold this. Check to see if it is actually
4777 // *profitable* to do so. We use a simple cost model to avoid increasing
4778 // register pressure too much.
4779 if (I->hasOneUse() ||
4780 isProfitableToFoldIntoAddressingMode(I, BackupAddrMode, AddrMode)) {
4781 AddrModeInsts.push_back(I);
4782 return true;
4783 }
4784
4785 // It isn't profitable to do this, roll back.
4786 //cerr << "NOT FOLDING: " << *I;
4787 AddrMode = BackupAddrMode;
4788 AddrModeInsts.resize(OldSize);
4789 TPT.rollback(LastKnownGood);
4790 }
4791 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Addr)) {
4792 if (matchOperationAddr(CE, CE->getOpcode(), Depth))
4793 return true;
4794 TPT.rollback(LastKnownGood);
4795 } else if (isa<ConstantPointerNull>(Addr)) {
4796 // Null pointer gets folded without affecting the addressing mode.
4797 return true;
4798 }
4799
4800 // Worse case, the target should support [reg] addressing modes. :)
4801 if (!AddrMode.HasBaseReg) {
4802 AddrMode.HasBaseReg = true;
4803 AddrMode.BaseReg = Addr;
4804 // Still check for legality in case the target supports [imm] but not [i+r].
4805 if (TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace))
4806 return true;
4807 AddrMode.HasBaseReg = false;
4808 AddrMode.BaseReg = nullptr;
4809 }
4810
4811 // If the base register is already taken, see if we can do [r+r].
4812 if (AddrMode.Scale == 0) {
4813 AddrMode.Scale = 1;
4814 AddrMode.ScaledReg = Addr;
4815 if (TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace))
4816 return true;
4817 AddrMode.Scale = 0;
4818 AddrMode.ScaledReg = nullptr;
4819 }
4820 // Couldn't match.
4821 TPT.rollback(LastKnownGood);
4822 return false;
4823}
4824
4825/// Check to see if all uses of OpVal by the specified inline asm call are due
4826/// to memory operands. If so, return true, otherwise return false.
4827static bool IsOperandAMemoryOperand(CallInst *CI, InlineAsm *IA, Value *OpVal,
4828 const TargetLowering &TLI,
4829 const TargetRegisterInfo &TRI) {
4830 const Function *F = CI->getFunction();
4831 TargetLowering::AsmOperandInfoVector TargetConstraints =
4832 TLI.ParseConstraints(F->getParent()->getDataLayout(), &TRI, *CI);
4833
4834 for (TargetLowering::AsmOperandInfo &OpInfo : TargetConstraints) {
4835 // Compute the constraint code and ConstraintType to use.
4836 TLI.ComputeConstraintToUse(OpInfo, SDValue());
4837
4838 // If this asm operand is our Value*, and if it isn't an indirect memory
4839 // operand, we can't fold it!
4840 if (OpInfo.CallOperandVal == OpVal &&
4841 (OpInfo.ConstraintType != TargetLowering::C_Memory ||
4842 !OpInfo.isIndirect))
4843 return false;
4844 }
4845
4846 return true;
4847}
4848
4849// Max number of memory uses to look at before aborting the search to conserve
4850// compile time.
4851static constexpr int MaxMemoryUsesToScan = 20;
4852
4853/// Recursively walk all the uses of I until we find a memory use.
4854/// If we find an obviously non-foldable instruction, return true.
4855/// Add accessed addresses and types to MemoryUses.
4856static bool FindAllMemoryUses(
4857 Instruction *I, SmallVectorImpl<std::pair<Value *, Type *>> &MemoryUses,
4858 SmallPtrSetImpl<Instruction *> &ConsideredInsts, const TargetLowering &TLI,
4859 const TargetRegisterInfo &TRI, bool OptSize, ProfileSummaryInfo *PSI,
4860 BlockFrequencyInfo *BFI, int SeenInsts = 0) {
4861 // If we already considered this instruction, we're done.
4862 if (!ConsideredInsts.insert(I).second)
4863 return false;
4864
4865 // If this is an obviously unfoldable instruction, bail out.
4866 if (!MightBeFoldableInst(I))
4867 return true;
4868
4869 // Loop over all the uses, recursively processing them.
4870 for (Use &U : I->uses()) {
4871 // Conservatively return true if we're seeing a large number or a deep chain
4872 // of users. This avoids excessive compilation times in pathological cases.
4873 if (SeenInsts++ >= MaxMemoryUsesToScan)
4874 return true;
4875
4876 Instruction *UserI = cast<Instruction>(U.getUser());
4877 if (LoadInst *LI = dyn_cast<LoadInst>(UserI)) {
4878 MemoryUses.push_back({U.get(), LI->getType()});
4879 continue;
4880 }
4881
4882 if (StoreInst *SI = dyn_cast<StoreInst>(UserI)) {
4883 if (U.getOperandNo() != StoreInst::getPointerOperandIndex())
4884 return true; // Storing addr, not into addr.
4885 MemoryUses.push_back({U.get(), SI->getValueOperand()->getType()});
4886 continue;
4887 }
4888
4889 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(UserI)) {
4890 if (U.getOperandNo() != AtomicRMWInst::getPointerOperandIndex())
4891 return true; // Storing addr, not into addr.
4892 MemoryUses.push_back({U.get(), RMW->getValOperand()->getType()});
4893 continue;
4894 }
4895
4896 if (AtomicCmpXchgInst *CmpX = dyn_cast<AtomicCmpXchgInst>(UserI)) {
4897 if (U.getOperandNo() != AtomicCmpXchgInst::getPointerOperandIndex())
4898 return true; // Storing addr, not into addr.
4899 MemoryUses.push_back({U.get(), CmpX->getCompareOperand()->getType()});
4900 continue;
4901 }
4902
4903 if (CallInst *CI = dyn_cast<CallInst>(UserI)) {
4904 if (CI->hasFnAttr(Attribute::Cold)) {
4905 // If this is a cold call, we can sink the addressing calculation into
4906 // the cold path. See optimizeCallInst
4907 bool OptForSize = OptSize ||
4908 llvm::shouldOptimizeForSize(CI->getParent(), PSI, BFI);
4909 if (!OptForSize)
4910 continue;
4911 }
4912
4913 InlineAsm *IA = dyn_cast<InlineAsm>(CI->getCalledOperand());
4914 if (!IA) return true;
4915
4916 // If this is a memory operand, we're cool, otherwise bail out.
4917 if (!IsOperandAMemoryOperand(CI, IA, I, TLI, TRI))
4918 return true;
4919 continue;
4920 }
4921
4922 if (FindAllMemoryUses(UserI, MemoryUses, ConsideredInsts, TLI, TRI, OptSize,
4923 PSI, BFI, SeenInsts))
4924 return true;
4925 }
4926
4927 return false;
4928}
4929
4930/// Return true if Val is already known to be live at the use site that we're
4931/// folding it into. If so, there is no cost to include it in the addressing
4932/// mode. KnownLive1 and KnownLive2 are two values that we know are live at the
4933/// instruction already.
4934bool AddressingModeMatcher::valueAlreadyLiveAtInst(Value *Val,Value *KnownLive1,
4935 Value *KnownLive2) {
4936 // If Val is either of the known-live values, we know it is live!
4937 if (Val == nullptr || Val == KnownLive1 || Val == KnownLive2)
4938 return true;
4939
4940 // All values other than instructions and arguments (e.g. constants) are live.
4941 if (!isa<Instruction>(Val) && !isa<Argument>(Val)) return true;
4942
4943 // If Val is a constant sized alloca in the entry block, it is live, this is
4944 // true because it is just a reference to the stack/frame pointer, which is
4945 // live for the whole function.
4946 if (AllocaInst *AI = dyn_cast<AllocaInst>(Val))
4947 if (AI->isStaticAlloca())
4948 return true;
4949
4950 // Check to see if this value is already used in the memory instruction's
4951 // block. If so, it's already live into the block at the very least, so we
4952 // can reasonably fold it.
4953 return Val->isUsedInBasicBlock(MemoryInst->getParent());
4954}
4955
4956/// It is possible for the addressing mode of the machine to fold the specified
4957/// instruction into a load or store that ultimately uses it.
4958/// However, the specified instruction has multiple uses.
4959/// Given this, it may actually increase register pressure to fold it
4960/// into the load. For example, consider this code:
4961///
4962/// X = ...
4963/// Y = X+1
4964/// use(Y) -> nonload/store
4965/// Z = Y+1
4966/// load Z
4967///
4968/// In this case, Y has multiple uses, and can be folded into the load of Z
4969/// (yielding load [X+2]). However, doing this will cause both "X" and "X+1" to
4970/// be live at the use(Y) line. If we don't fold Y into load Z, we use one
4971/// fewer register. Since Y can't be folded into "use(Y)" we don't increase the
4972/// number of computations either.
4973///
4974/// Note that this (like most of CodeGenPrepare) is just a rough heuristic. If
4975/// X was live across 'load Z' for other reasons, we actually *would* want to
4976/// fold the addressing mode in the Z case. This would make Y die earlier.
4977bool AddressingModeMatcher::
4978isProfitableToFoldIntoAddressingMode(Instruction *I, ExtAddrMode &AMBefore,
4979 ExtAddrMode &AMAfter) {
4980 if (IgnoreProfitability) return true;
4981
4982 // AMBefore is the addressing mode before this instruction was folded into it,
4983 // and AMAfter is the addressing mode after the instruction was folded. Get
4984 // the set of registers referenced by AMAfter and subtract out those
4985 // referenced by AMBefore: this is the set of values which folding in this
4986 // address extends the lifetime of.
4987 //
4988 // Note that there are only two potential values being referenced here,
4989 // BaseReg and ScaleReg (global addresses are always available, as are any
4990 // folded immediates).
4991 Value *BaseReg = AMAfter.BaseReg, *ScaledReg = AMAfter.ScaledReg;
4992
4993 // If the BaseReg or ScaledReg was referenced by the previous addrmode, their
4994 // lifetime wasn't extended by adding this instruction.
4995 if (valueAlreadyLiveAtInst(BaseReg, AMBefore.BaseReg, AMBefore.ScaledReg))
4996 BaseReg = nullptr;
4997 if (valueAlreadyLiveAtInst(ScaledReg, AMBefore.BaseReg, AMBefore.ScaledReg))
4998 ScaledReg = nullptr;
4999
5000 // If folding this instruction (and it's subexprs) didn't extend any live
5001 // ranges, we're ok with it.
5002 if (!BaseReg && !ScaledReg)
5003 return true;
5004
5005 // If all uses of this instruction can have the address mode sunk into them,
5006 // we can remove the addressing mode and effectively trade one live register
5007 // for another (at worst.) In this context, folding an addressing mode into
5008 // the use is just a particularly nice way of sinking it.
5009 SmallVector<std::pair<Value *, Type *>, 16> MemoryUses;
5010 SmallPtrSet<Instruction*, 16> ConsideredInsts;
5011 if (FindAllMemoryUses(I, MemoryUses, ConsideredInsts, TLI, TRI, OptSize,
5012 PSI, BFI))
5013 return false; // Has a non-memory, non-foldable use!
5014
5015 // Now that we know that all uses of this instruction are part of a chain of
5016 // computation involving only operations that could theoretically be folded
5017 // into a memory use, loop over each of these memory operation uses and see
5018 // if they could *actually* fold the instruction. The assumption is that
5019 // addressing modes are cheap and that duplicating the computation involved
5020 // many times is worthwhile, even on a fastpath. For sinking candidates
5021 // (i.e. cold call sites), this serves as a way to prevent excessive code
5022 // growth since most architectures have some reasonable small and fast way to
5023 // compute an effective address. (i.e LEA on x86)
5024 SmallVector<Instruction*, 32> MatchedAddrModeInsts;
5025 for (const std::pair<Value *, Type *> &Pair : MemoryUses) {
5026 Value *Address = Pair.first;
5027 Type *AddressAccessTy = Pair.second;
5028 unsigned AS = Address->getType()->getPointerAddressSpace();
5029
5030 // Do a match against the root of this address, ignoring profitability. This
5031 // will tell us if the addressing mode for the memory operation will
5032 // *actually* cover the shared instruction.
5033 ExtAddrMode Result;
5034 std::pair<AssertingVH<GetElementPtrInst>, int64_t> LargeOffsetGEP(nullptr,
5035 0);
5036 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
5037 TPT.getRestorationPoint();
5038 AddressingModeMatcher Matcher(MatchedAddrModeInsts, TLI, TRI, LI, getDTFn,
5039 AddressAccessTy, AS, MemoryInst, Result,
5040 InsertedInsts, PromotedInsts, TPT,
5041 LargeOffsetGEP, OptSize, PSI, BFI);
5042 Matcher.IgnoreProfitability = true;
5043 bool Success = Matcher.matchAddr(Address, 0);
5044 (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*?\""
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 5044, __extension__ __PRETTY_FUNCTION__
))
;
5045
5046 // The match was to check the profitability, the changes made are not
5047 // part of the original matcher. Therefore, they should be dropped
5048 // otherwise the original matcher will not present the right state.
5049 TPT.rollback(LastKnownGood);
5050
5051 // If the match didn't cover I, then it won't be shared by it.
5052 if (!is_contained(MatchedAddrModeInsts, I))
5053 return false;
5054
5055 MatchedAddrModeInsts.clear();
5056 }
5057
5058 return true;
5059}
5060
5061/// Return true if the specified values are defined in a
5062/// different basic block than BB.
5063static bool IsNonLocalValue(Value *V, BasicBlock *BB) {
5064 if (Instruction *I = dyn_cast<Instruction>(V))
5065 return I->getParent() != BB;
5066 return false;
5067}
5068
5069/// Sink addressing mode computation immediate before MemoryInst if doing so
5070/// can be done without increasing register pressure. The need for the
5071/// register pressure constraint means this can end up being an all or nothing
5072/// decision for all uses of the same addressing computation.
5073///
5074/// Load and Store Instructions often have addressing modes that can do
5075/// significant amounts of computation. As such, instruction selection will try
5076/// to get the load or store to do as much computation as possible for the
5077/// program. The problem is that isel can only see within a single block. As
5078/// such, we sink as much legal addressing mode work into the block as possible.
5079///
5080/// This method is used to optimize both load/store and inline asms with memory
5081/// operands. It's also used to sink addressing computations feeding into cold
5082/// call sites into their (cold) basic block.
5083///
5084/// The motivation for handling sinking into cold blocks is that doing so can
5085/// both enable other address mode sinking (by satisfying the register pressure
5086/// constraint above), and reduce register pressure globally (by removing the
5087/// addressing mode computation from the fast path entirely.).
5088bool CodeGenPrepare::optimizeMemoryInst(Instruction *MemoryInst, Value *Addr,
5089 Type *AccessTy, unsigned AddrSpace) {
5090 Value *Repl = Addr;
5091
5092 // Try to collapse single-value PHI nodes. This is necessary to undo
5093 // unprofitable PRE transformations.
5094 SmallVector<Value*, 8> worklist;
5095 SmallPtrSet<Value*, 16> Visited;
5096 worklist.push_back(Addr);
5097
5098 // Use a worklist to iteratively look through PHI and select nodes, and
5099 // ensure that the addressing mode obtained from the non-PHI/select roots of
5100 // the graph are compatible.
5101 bool PhiOrSelectSeen = false;
5102 SmallVector<Instruction*, 16> AddrModeInsts;
5103 const SimplifyQuery SQ(*DL, TLInfo);
5104 AddressingModeCombiner AddrModes(SQ, Addr);
5105 TypePromotionTransaction TPT(RemovedInsts);
5106 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
5107 TPT.getRestorationPoint();
5108 while (!worklist.empty()) {
5109 Value *V = worklist.pop_back_val();
5110
5111 // We allow traversing cyclic Phi nodes.
5112 // In case of success after this loop we ensure that traversing through
5113 // Phi nodes ends up with all cases to compute address of the form
5114 // BaseGV + Base + Scale * Index + Offset
5115 // where Scale and Offset are constans and BaseGV, Base and Index
5116 // are exactly the same Values in all cases.
5117 // It means that BaseGV, Scale and Offset dominate our memory instruction
5118 // and have the same value as they had in address computation represented
5119 // as Phi. So we can safely sink address computation to memory instruction.
5120 if (!Visited.insert(V).second)
5121 continue;
5122
5123 // For a PHI node, push all of its incoming values.
5124 if (PHINode *P = dyn_cast<PHINode>(V)) {
5125 append_range(worklist, P->incoming_values());
5126 PhiOrSelectSeen = true;
5127 continue;
5128 }
5129 // Similar for select.
5130 if (SelectInst *SI = dyn_cast<SelectInst>(V)) {
5131 worklist.push_back(SI->getFalseValue());
5132 worklist.push_back(SI->getTrueValue());
5133 PhiOrSelectSeen = true;
5134 continue;
5135 }
5136
5137 // For non-PHIs, determine the addressing mode being computed. Note that
5138 // the result may differ depending on what other uses our candidate
5139 // addressing instructions might have.
5140 AddrModeInsts.clear();
5141 std::pair<AssertingVH<GetElementPtrInst>, int64_t> LargeOffsetGEP(nullptr,
5142 0);
5143 // Defer the query (and possible computation of) the dom tree to point of
5144 // actual use. It's expected that most address matches don't actually need
5145 // the domtree.
5146 auto getDTFn = [MemoryInst, this]() -> const DominatorTree & {
5147 Function *F = MemoryInst->getParent()->getParent();
5148 return this->getDT(*F);
5149 };
5150 ExtAddrMode NewAddrMode = AddressingModeMatcher::Match(
5151 V, AccessTy, AddrSpace, MemoryInst, AddrModeInsts, *TLI, *LI, getDTFn,
5152 *TRI, InsertedInsts, PromotedInsts, TPT, LargeOffsetGEP, OptSize, PSI,
5153 BFI.get());
5154
5155 GetElementPtrInst *GEP = LargeOffsetGEP.first;
5156 if (GEP && !NewGEPBases.count(GEP)) {
5157 // If splitting the underlying data structure can reduce the offset of a
5158 // GEP, collect the GEP. Skip the GEPs that are the new bases of
5159 // previously split data structures.
5160 LargeOffsetGEPMap[GEP->getPointerOperand()].push_back(LargeOffsetGEP);
5161 if (LargeOffsetGEPID.find(GEP) == LargeOffsetGEPID.end())
5162 LargeOffsetGEPID[GEP] = LargeOffsetGEPID.size();
5163 }
5164
5165 NewAddrMode.OriginalValue = V;
5166 if (!AddrModes.addNewAddrMode(NewAddrMode))
5167 break;
5168 }
5169
5170 // Try to combine the AddrModes we've collected. If we couldn't collect any,
5171 // or we have multiple but either couldn't combine them or combining them
5172 // wouldn't do anything useful, bail out now.
5173 if (!AddrModes.combineAddrModes()) {
5174 TPT.rollback(LastKnownGood);
5175 return false;
5176 }
5177 bool Modified = TPT.commit();
5178
5179 // Get the combined AddrMode (or the only AddrMode, if we only had one).
5180 ExtAddrMode AddrMode = AddrModes.getAddrMode();
5181
5182 // If all the instructions matched are already in this BB, don't do anything.
5183 // If we saw a Phi node then it is not local definitely, and if we saw a select
5184 // then we want to push the address calculation past it even if it's already
5185 // in this BB.
5186 if (!PhiOrSelectSeen && none_of(AddrModeInsts, [&](Value *V) {
5187 return IsNonLocalValue(V, MemoryInst->getParent());
5188 })) {
5189 LLVM_DEBUG(dbgs() << "CGP: Found local addrmode: " << AddrModedo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: Found local addrmode: "
<< AddrMode << "\n"; } } while (false)
5190 << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: Found local addrmode: "
<< AddrMode << "\n"; } } while (false)
;
5191 return Modified;
5192 }
5193
5194 // Insert this computation right after this user. Since our caller is
5195 // scanning from the top of the BB to the bottom, reuse of the expr are
5196 // guaranteed to happen later.
5197 IRBuilder<> Builder(MemoryInst);
5198
5199 // Now that we determined the addressing expression we want to use and know
5200 // that we have to sink it into this block. Check to see if we have already
5201 // done this for some other load/store instr in this block. If so, reuse
5202 // the computation. Before attempting reuse, check if the address is valid
5203 // as it may have been erased.
5204
5205 WeakTrackingVH SunkAddrVH = SunkAddrs[Addr];
5206
5207 Value * SunkAddr = SunkAddrVH.pointsToAliveValue() ? SunkAddrVH : nullptr;
5208 if (SunkAddr) {
5209 LLVM_DEBUG(dbgs() << "CGP: Reusing nonlocal addrmode: " << AddrModedo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: Reusing nonlocal addrmode: "
<< AddrMode << " for " << *MemoryInst <<
"\n"; } } while (false)
5210 << " for " << *MemoryInst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: Reusing nonlocal addrmode: "
<< AddrMode << " for " << *MemoryInst <<
"\n"; } } while (false)
;
5211 if (SunkAddr->getType() != Addr->getType())
5212 SunkAddr = Builder.CreatePointerCast(SunkAddr, Addr->getType());
5213 } else if (AddrSinkUsingGEPs || (!AddrSinkUsingGEPs.getNumOccurrences() &&
5214 SubtargetInfo->addrSinkUsingGEPs())) {
5215 // By default, we use the GEP-based method when AA is used later. This
5216 // prevents new inttoptr/ptrtoint pairs from degrading AA capabilities.
5217 LLVM_DEBUG(dbgs() << "CGP: SINKING nonlocal addrmode: " << AddrModedo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: SINKING nonlocal addrmode: "
<< AddrMode << " for " << *MemoryInst <<
"\n"; } } while (false)
5218 << " for " << *MemoryInst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: SINKING nonlocal addrmode: "
<< AddrMode << " for " << *MemoryInst <<
"\n"; } } while (false)
;
5219 Type *IntPtrTy = DL->getIntPtrType(Addr->getType());
5220 Value *ResultPtr = nullptr, *ResultIndex = nullptr;
5221
5222 // First, find the pointer.
5223 if (AddrMode.BaseReg && AddrMode.BaseReg->getType()->isPointerTy()) {
5224 ResultPtr = AddrMode.BaseReg;
5225 AddrMode.BaseReg = nullptr;
5226 }
5227
5228 if (AddrMode.Scale && AddrMode.ScaledReg->getType()->isPointerTy()) {
5229 // We can't add more than one pointer together, nor can we scale a
5230 // pointer (both of which seem meaningless).
5231 if (ResultPtr || AddrMode.Scale != 1)
5232 return Modified;
5233
5234 ResultPtr = AddrMode.ScaledReg;
5235 AddrMode.Scale = 0;
5236 }
5237
5238 // It is only safe to sign extend the BaseReg if we know that the math
5239 // required to create it did not overflow before we extend it. Since
5240 // the original IR value was tossed in favor of a constant back when
5241 // the AddrMode was created we need to bail out gracefully if widths
5242 // do not match instead of extending it.
5243 //
5244 // (See below for code to add the scale.)
5245 if (AddrMode.Scale) {
5246 Type *ScaledRegTy = AddrMode.ScaledReg->getType();
5247 if (cast<IntegerType>(IntPtrTy)->getBitWidth() >
5248 cast<IntegerType>(ScaledRegTy)->getBitWidth())
5249 return Modified;
5250 }
5251
5252 if (AddrMode.BaseGV) {
5253 if (ResultPtr)
5254 return Modified;
5255
5256 ResultPtr = AddrMode.BaseGV;
5257 }
5258
5259 // If the real base value actually came from an inttoptr, then the matcher
5260 // will look through it and provide only the integer value. In that case,
5261 // use it here.
5262 if (!DL->isNonIntegralPointerType(Addr->getType())) {
5263 if (!ResultPtr && AddrMode.BaseReg) {
5264 ResultPtr = Builder.CreateIntToPtr(AddrMode.BaseReg, Addr->getType(),
5265 "sunkaddr");
5266 AddrMode.BaseReg = nullptr;
5267 } else if (!ResultPtr && AddrMode.Scale == 1) {
5268 ResultPtr = Builder.CreateIntToPtr(AddrMode.ScaledReg, Addr->getType(),
5269 "sunkaddr");
5270 AddrMode.Scale = 0;
5271 }
5272 }
5273
5274 if (!ResultPtr &&
5275 !AddrMode.BaseReg && !AddrMode.Scale && !AddrMode.BaseOffs) {
5276 SunkAddr = Constant::getNullValue(Addr->getType());
5277 } else if (!ResultPtr) {
5278 return Modified;
5279 } else {
5280 Type *I8PtrTy =
5281 Builder.getInt8PtrTy(Addr->getType()->getPointerAddressSpace());
5282 Type *I8Ty = Builder.getInt8Ty();
5283
5284 // Start with the base register. Do this first so that subsequent address
5285 // matching finds it last, which will prevent it from trying to match it
5286 // as the scaled value in case it happens to be a mul. That would be
5287 // problematic if we've sunk a different mul for the scale, because then
5288 // we'd end up sinking both muls.
5289 if (AddrMode.BaseReg) {
5290 Value *V = AddrMode.BaseReg;
5291 if (V->getType() != IntPtrTy)
5292 V = Builder.CreateIntCast(V, IntPtrTy, /*isSigned=*/true, "sunkaddr");
5293
5294 ResultIndex = V;
5295 }
5296
5297 // Add the scale value.
5298 if (AddrMode.Scale) {
5299 Value *V = AddrMode.ScaledReg;
5300 if (V->getType() == IntPtrTy) {
5301 // done.
5302 } else {
5303 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\""
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 5305, __extension__ __PRETTY_FUNCTION__
))
5304 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\""
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 5305, __extension__ __PRETTY_FUNCTION__
))
5305 "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\""
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 5305, __extension__ __PRETTY_FUNCTION__
))
;
5306 V = Builder.CreateTrunc(V, IntPtrTy, "sunkaddr");
5307 }
5308
5309 if (AddrMode.Scale != 1)
5310 V = Builder.CreateMul(V, ConstantInt::get(IntPtrTy, AddrMode.Scale),
5311 "sunkaddr");
5312 if (ResultIndex)
5313 ResultIndex = Builder.CreateAdd(ResultIndex, V, "sunkaddr");
5314 else
5315 ResultIndex = V;
5316 }
5317
5318 // Add in the Base Offset if present.
5319 if (AddrMode.BaseOffs) {
5320 Value *V = ConstantInt::get(IntPtrTy, AddrMode.BaseOffs);
5321 if (ResultIndex) {
5322 // We need to add this separately from the scale above to help with
5323 // SDAG consecutive load/store merging.
5324 if (ResultPtr->getType() != I8PtrTy)
5325 ResultPtr = Builder.CreatePointerCast(ResultPtr, I8PtrTy);
5326 ResultPtr =
5327 AddrMode.InBounds
5328 ? Builder.CreateInBoundsGEP(I8Ty, ResultPtr, ResultIndex,
5329 "sunkaddr")
5330 : Builder.CreateGEP(I8Ty, ResultPtr, ResultIndex, "sunkaddr");
5331 }
5332
5333 ResultIndex = V;
5334 }
5335
5336 if (!ResultIndex) {
5337 SunkAddr = ResultPtr;
5338 } else {
5339 if (ResultPtr->getType() != I8PtrTy)
5340 ResultPtr = Builder.CreatePointerCast(ResultPtr, I8PtrTy);
5341 SunkAddr =
5342 AddrMode.InBounds
5343 ? Builder.CreateInBoundsGEP(I8Ty, ResultPtr, ResultIndex,
5344 "sunkaddr")
5345 : Builder.CreateGEP(I8Ty, ResultPtr, ResultIndex, "sunkaddr");
5346 }
5347
5348 if (SunkAddr->getType() != Addr->getType())
5349 SunkAddr = Builder.CreatePointerCast(SunkAddr, Addr->getType());
5350 }
5351 } else {
5352 // We'd require a ptrtoint/inttoptr down the line, which we can't do for
5353 // non-integral pointers, so in that case bail out now.
5354 Type *BaseTy = AddrMode.BaseReg ? AddrMode.BaseReg->getType() : nullptr;
5355 Type *ScaleTy = AddrMode.Scale ? AddrMode.ScaledReg->getType() : nullptr;
5356 PointerType *BasePtrTy = dyn_cast_or_null<PointerType>(BaseTy);
5357 PointerType *ScalePtrTy = dyn_cast_or_null<PointerType>(ScaleTy);
5358 if (DL->isNonIntegralPointerType(Addr->getType()) ||
5359 (BasePtrTy && DL->isNonIntegralPointerType(BasePtrTy)) ||
5360 (ScalePtrTy && DL->isNonIntegralPointerType(ScalePtrTy)) ||
5361 (AddrMode.BaseGV &&
5362 DL->isNonIntegralPointerType(AddrMode.BaseGV->getType())))
5363 return Modified;
5364
5365 LLVM_DEBUG(dbgs() << "CGP: SINKING nonlocal addrmode: " << AddrModedo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: SINKING nonlocal addrmode: "
<< AddrMode << " for " << *MemoryInst <<
"\n"; } } while (false)
5366 << " for " << *MemoryInst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: SINKING nonlocal addrmode: "
<< AddrMode << " for " << *MemoryInst <<
"\n"; } } while (false)
;
5367 Type *IntPtrTy = DL->getIntPtrType(Addr->getType());
5368 Value *Result = nullptr;
5369
5370 // Start with the base register. Do this first so that subsequent address
5371 // matching finds it last, which will prevent it from trying to match it
5372 // as the scaled value in case it happens to be a mul. That would be
5373 // problematic if we've sunk a different mul for the scale, because then
5374 // we'd end up sinking both muls.
5375 if (AddrMode.BaseReg) {
5376 Value *V = AddrMode.BaseReg;
5377 if (V->getType()->isPointerTy())
5378 V = Builder.CreatePtrToInt(V, IntPtrTy, "sunkaddr");
5379 if (V->getType() != IntPtrTy)
5380 V = Builder.CreateIntCast(V, IntPtrTy, /*isSigned=*/true, "sunkaddr");
5381 Result = V;
5382 }
5383
5384 // Add the scale value.
5385 if (AddrMode.Scale) {
5386 Value *V = AddrMode.ScaledReg;
5387 if (V->getType() == IntPtrTy) {
5388 // done.
5389 } else if (V->getType()->isPointerTy()) {
5390 V = Builder.CreatePtrToInt(V, IntPtrTy, "sunkaddr");
5391 } else if (cast<IntegerType>(IntPtrTy)->getBitWidth() <
5392 cast<IntegerType>(V->getType())->getBitWidth()) {
5393 V = Builder.CreateTrunc(V, IntPtrTy, "sunkaddr");
5394 } else {
5395 // It is only safe to sign extend the BaseReg if we know that the math
5396 // required to create it did not overflow before we extend it. Since
5397 // the original IR value was tossed in favor of a constant back when
5398 // the AddrMode was created we need to bail out gracefully if widths
5399 // do not match instead of extending it.
5400 Instruction *I = dyn_cast_or_null<Instruction>(Result);
5401 if (I && (Result != AddrMode.BaseReg))
5402 I->eraseFromParent();
5403 return Modified;
5404 }
5405 if (AddrMode.Scale != 1)
5406 V = Builder.CreateMul(V, ConstantInt::get(IntPtrTy, AddrMode.Scale),
5407 "sunkaddr");
5408 if (Result)
5409 Result = Builder.CreateAdd(Result, V, "sunkaddr");
5410 else
5411 Result = V;
5412 }
5413
5414 // Add in the BaseGV if present.
5415 if (AddrMode.BaseGV) {
5416 Value *V = Builder.CreatePtrToInt(AddrMode.BaseGV, IntPtrTy, "sunkaddr");
5417 if (Result)
5418 Result = Builder.CreateAdd(Result, V, "sunkaddr");
5419 else
5420 Result = V;
5421 }
5422
5423 // Add in the Base Offset if present.
5424 if (AddrMode.BaseOffs) {
5425 Value *V = ConstantInt::get(IntPtrTy, AddrMode.BaseOffs);
5426 if (Result)
5427 Result = Builder.CreateAdd(Result, V, "sunkaddr");
5428 else
5429 Result = V;
5430 }
5431
5432 if (!Result)
5433 SunkAddr = Constant::getNullValue(Addr->getType());
5434 else
5435 SunkAddr = Builder.CreateIntToPtr(Result, Addr->getType(), "sunkaddr");
5436 }
5437
5438 MemoryInst->replaceUsesOfWith(Repl, SunkAddr);
5439 // Store the newly computed address into the cache. In the case we reused a
5440 // value, this should be idempotent.
5441 SunkAddrs[Addr] = WeakTrackingVH(SunkAddr);
5442
5443 // If we have no uses, recursively delete the value and all dead instructions
5444 // using it.
5445 if (Repl->use_empty()) {
5446 resetIteratorIfInvalidatedWhileCalling(CurInstIterator->getParent(), [&]() {
5447 RecursivelyDeleteTriviallyDeadInstructions(
5448 Repl, TLInfo, nullptr,
5449 [&](Value *V) { removeAllAssertingVHReferences(V); });
5450 });
5451 }
5452 ++NumMemoryInsts;
5453 return true;
5454}
5455
5456/// Rewrite GEP input to gather/scatter to enable SelectionDAGBuilder to find
5457/// a uniform base to use for ISD::MGATHER/MSCATTER. SelectionDAGBuilder can
5458/// only handle a 2 operand GEP in the same basic block or a splat constant
5459/// vector. The 2 operands to the GEP must have a scalar pointer and a vector
5460/// index.
5461///
5462/// If the existing GEP has a vector base pointer that is splat, we can look
5463/// through the splat to find the scalar pointer. If we can't find a scalar
5464/// pointer there's nothing we can do.
5465///
5466/// If we have a GEP with more than 2 indices where the middle indices are all
5467/// zeroes, we can replace it with 2 GEPs where the second has 2 operands.
5468///
5469/// If the final index isn't a vector or is a splat, we can emit a scalar GEP
5470/// followed by a GEP with an all zeroes vector index. This will enable
5471/// SelectionDAGBuilder to use the scalar GEP as the uniform base and have a
5472/// zero index.
5473bool CodeGenPrepare::optimizeGatherScatterInst(Instruction *MemoryInst,
5474 Value *Ptr) {
5475 Value *NewAddr;
5476
5477 if (const auto *GEP = dyn_cast<GetElementPtrInst>(Ptr)) {
5478 // Don't optimize GEPs that don't have indices.
5479 if (!GEP->hasIndices())
5480 return false;
5481
5482 // If the GEP and the gather/scatter aren't in the same BB, don't optimize.
5483 // FIXME: We should support this by sinking the GEP.
5484 if (MemoryInst->getParent() != GEP->getParent())
5485 return false;
5486
5487 SmallVector<Value *, 2> Ops(GEP->operands());
5488
5489 bool RewriteGEP = false;
5490
5491 if (Ops[0]->getType()->isVectorTy()) {
5492 Ops[0] = getSplatValue(Ops[0]);
5493 if (!Ops[0])
5494 return false;
5495 RewriteGEP = true;
5496 }
5497
5498 unsigned FinalIndex = Ops.size() - 1;
5499
5500 // Ensure all but the last index is 0.
5501 // FIXME: This isn't strictly required. All that's required is that they are
5502 // all scalars or splats.
5503 for (unsigned i = 1; i < FinalIndex; ++i) {
5504 auto *C = dyn_cast<Constant>(Ops[i]);
5505 if (!C)
5506 return false;
5507 if (isa<VectorType>(C->getType()))
5508 C = C->getSplatValue();
5509 auto *CI = dyn_cast_or_null<ConstantInt>(C);
5510 if (!CI || !CI->isZero())
5511 return false;
5512 // Scalarize the index if needed.
5513 Ops[i] = CI;
5514 }
5515
5516 // Try to scalarize the final index.
5517 if (Ops[FinalIndex]->getType()->isVectorTy()) {
5518 if (Value *V = getSplatValue(Ops[FinalIndex])) {
5519 auto *C = dyn_cast<ConstantInt>(V);
5520 // Don't scalarize all zeros vector.
5521 if (!C || !C->isZero()) {
5522 Ops[FinalIndex] = V;
5523 RewriteGEP = true;
5524 }
5525 }
5526 }
5527
5528 // If we made any changes or the we have extra operands, we need to generate
5529 // new instructions.
5530 if (!RewriteGEP && Ops.size() == 2)
5531 return false;
5532
5533 auto NumElts = cast<VectorType>(Ptr->getType())->getElementCount();
5534
5535 IRBuilder<> Builder(MemoryInst);
5536
5537 Type *SourceTy = GEP->getSourceElementType();
5538 Type *ScalarIndexTy = DL->getIndexType(Ops[0]->getType()->getScalarType());
5539
5540 // If the final index isn't a vector, emit a scalar GEP containing all ops
5541 // and a vector GEP with all zeroes final index.
5542 if (!Ops[FinalIndex]->getType()->isVectorTy()) {
5543 NewAddr = Builder.CreateGEP(SourceTy, Ops[0],
5544 makeArrayRef(Ops).drop_front());
5545 auto *IndexTy = VectorType::get(ScalarIndexTy, NumElts);
5546 auto *SecondTy = GetElementPtrInst::getIndexedType(
5547 SourceTy, makeArrayRef(Ops).drop_front());
5548 NewAddr =
5549 Builder.CreateGEP(SecondTy, NewAddr, Constant::getNullValue(IndexTy));
5550 } else {
5551 Value *Base = Ops[0];
5552 Value *Index = Ops[FinalIndex];
5553
5554 // Create a scalar GEP if there are more than 2 operands.
5555 if (Ops.size() != 2) {
5556 // Replace the last index with 0.
5557 Ops[FinalIndex] = Constant::getNullValue(ScalarIndexTy);
5558 Base = Builder.CreateGEP(SourceTy, Base,
5559 makeArrayRef(Ops).drop_front());
5560 SourceTy = GetElementPtrInst::getIndexedType(
5561 SourceTy, makeArrayRef(Ops).drop_front());
5562 }
5563
5564 // Now create the GEP with scalar pointer and vector index.
5565 NewAddr = Builder.CreateGEP(SourceTy, Base, Index);
5566 }
5567 } else if (!isa<Constant>(Ptr)) {
5568 // Not a GEP, maybe its a splat and we can create a GEP to enable
5569 // SelectionDAGBuilder to use it as a uniform base.
5570 Value *V = getSplatValue(Ptr);
5571 if (!V)
5572 return false;
5573
5574 auto NumElts = cast<VectorType>(Ptr->getType())->getElementCount();
5575
5576 IRBuilder<> Builder(MemoryInst);
5577
5578 // Emit a vector GEP with a scalar pointer and all 0s vector index.
5579 Type *ScalarIndexTy = DL->getIndexType(V->getType()->getScalarType());
5580 auto *IndexTy = VectorType::get(ScalarIndexTy, NumElts);
5581 Type *ScalarTy;
5582 if (cast<IntrinsicInst>(MemoryInst)->getIntrinsicID() ==
5583 Intrinsic::masked_gather) {
5584 ScalarTy = MemoryInst->getType()->getScalarType();
5585 } else {
5586 assert(cast<IntrinsicInst>(MemoryInst)->getIntrinsicID() ==(static_cast <bool> (cast<IntrinsicInst>(MemoryInst
)->getIntrinsicID() == Intrinsic::masked_scatter) ? void (
0) : __assert_fail ("cast<IntrinsicInst>(MemoryInst)->getIntrinsicID() == Intrinsic::masked_scatter"
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 5587, __extension__ __PRETTY_FUNCTION__
))
5587 Intrinsic::masked_scatter)(static_cast <bool> (cast<IntrinsicInst>(MemoryInst
)->getIntrinsicID() == Intrinsic::masked_scatter) ? void (
0) : __assert_fail ("cast<IntrinsicInst>(MemoryInst)->getIntrinsicID() == Intrinsic::masked_scatter"
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 5587, __extension__ __PRETTY_FUNCTION__
))
;
5588 ScalarTy = MemoryInst->getOperand(0)->getType()->getScalarType();
5589 }
5590 NewAddr = Builder.CreateGEP(ScalarTy, V, Constant::getNullValue(IndexTy));
5591 } else {
5592 // Constant, SelectionDAGBuilder knows to check if its a splat.
5593 return false;
5594 }
5595
5596 MemoryInst->replaceUsesOfWith(Ptr, NewAddr);
5597
5598 // If we have no uses, recursively delete the value and all dead instructions
5599 // using it.
5600 if (Ptr->use_empty())
5601 RecursivelyDeleteTriviallyDeadInstructions(
5602 Ptr, TLInfo, nullptr,
5603 [&](Value *V) { removeAllAssertingVHReferences(V); });
5604
5605 return true;
5606}
5607
5608/// If there are any memory operands, use OptimizeMemoryInst to sink their
5609/// address computing into the block when possible / profitable.
5610bool CodeGenPrepare::optimizeInlineAsmInst(CallInst *CS) {
5611 bool MadeChange = false;
5612
5613 const TargetRegisterInfo *TRI =
5614 TM->getSubtargetImpl(*CS->getFunction())->getRegisterInfo();
5615 TargetLowering::AsmOperandInfoVector TargetConstraints =
5616 TLI->ParseConstraints(*DL, TRI, *CS);
5617 unsigned ArgNo = 0;
5618 for (TargetLowering::AsmOperandInfo &OpInfo : TargetConstraints) {
5619 // Compute the constraint code and ConstraintType to use.
5620 TLI->ComputeConstraintToUse(OpInfo, SDValue());
5621
5622 if (OpInfo.ConstraintType == TargetLowering::C_Memory &&
5623 OpInfo.isIndirect) {
5624 Value *OpVal = CS->getArgOperand(ArgNo++);
5625 MadeChange |= optimizeMemoryInst(CS, OpVal, OpVal->getType(), ~0u);
5626 } else if (OpInfo.Type == InlineAsm::isInput)
5627 ArgNo++;
5628 }
5629
5630 return MadeChange;
5631}
5632
5633/// Check if all the uses of \p Val are equivalent (or free) zero or
5634/// sign extensions.
5635static bool hasSameExtUse(Value *Val, const TargetLowering &TLI) {
5636 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\""
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 5636, __extension__ __PRETTY_FUNCTION__
))
;
5637 const Instruction *FirstUser = cast<Instruction>(*Val->user_begin());
5638 bool IsSExt = isa<SExtInst>(FirstUser);
5639 Type *ExtTy = FirstUser->getType();
5640 for (const User *U : Val->users()) {
5641 const Instruction *UI = cast<Instruction>(U);
5642 if ((IsSExt && !isa<SExtInst>(UI)) || (!IsSExt && !isa<ZExtInst>(UI)))
5643 return false;
5644 Type *CurTy = UI->getType();
5645 // Same input and output types: Same instruction after CSE.
5646 if (CurTy == ExtTy)
5647 continue;
5648
5649 // If IsSExt is true, we are in this situation:
5650 // a = Val
5651 // b = sext ty1 a to ty2
5652 // c = sext ty1 a to ty3
5653 // Assuming ty2 is shorter than ty3, this could be turned into:
5654 // a = Val
5655 // b = sext ty1 a to ty2
5656 // c = sext ty2 b to ty3
5657 // However, the last sext is not free.
5658 if (IsSExt)
5659 return false;
5660
5661 // This is a ZExt, maybe this is free to extend from one type to another.
5662 // In that case, we would not account for a different use.
5663 Type *NarrowTy;
5664 Type *LargeTy;
5665 if (ExtTy->getScalarType()->getIntegerBitWidth() >
5666 CurTy->getScalarType()->getIntegerBitWidth()) {
5667 NarrowTy = CurTy;
5668 LargeTy = ExtTy;
5669 } else {
5670 NarrowTy = ExtTy;
5671 LargeTy = CurTy;
5672 }
5673
5674 if (!TLI.isZExtFree(NarrowTy, LargeTy))
5675 return false;
5676 }
5677 // All uses are the same or can be derived from one another for free.
5678 return true;
5679}
5680
5681/// Try to speculatively promote extensions in \p Exts and continue
5682/// promoting through newly promoted operands recursively as far as doing so is
5683/// profitable. Save extensions profitably moved up, in \p ProfitablyMovedExts.
5684/// When some promotion happened, \p TPT contains the proper state to revert
5685/// them.
5686///
5687/// \return true if some promotion happened, false otherwise.
5688bool CodeGenPrepare::tryToPromoteExts(
5689 TypePromotionTransaction &TPT, const SmallVectorImpl<Instruction *> &Exts,
5690 SmallVectorImpl<Instruction *> &ProfitablyMovedExts,
5691 unsigned CreatedInstsCost) {
5692 bool Promoted = false;
5693
5694 // Iterate over all the extensions to try to promote them.
5695 for (auto *I : Exts) {
5696 // Early check if we directly have ext(load).
5697 if (isa<LoadInst>(I->getOperand(0))) {
5698 ProfitablyMovedExts.push_back(I);
5699 continue;
5700 }
5701
5702 // Check whether or not we want to do any promotion. The reason we have
5703 // this check inside the for loop is to catch the case where an extension
5704 // is directly fed by a load because in such case the extension can be moved
5705 // up without any promotion on its operands.
5706 if (!TLI->enableExtLdPromotion() || DisableExtLdPromotion)
5707 return false;
5708
5709 // Get the action to perform the promotion.
5710 TypePromotionHelper::Action TPH =
5711 TypePromotionHelper::getAction(I, InsertedInsts, *TLI, PromotedInsts);
5712 // Check if we can promote.
5713 if (!TPH) {
5714 // Save the current extension as we cannot move up through its operand.
5715 ProfitablyMovedExts.push_back(I);
5716 continue;
5717 }
5718
5719 // Save the current state.
5720 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
5721 TPT.getRestorationPoint();
5722 SmallVector<Instruction *, 4> NewExts;
5723 unsigned NewCreatedInstsCost = 0;
5724 unsigned ExtCost = !TLI->isExtFree(I);
5725 // Promote.
5726 Value *PromotedVal = TPH(I, TPT, PromotedInsts, NewCreatedInstsCost,
5727 &NewExts, nullptr, *TLI);
5728 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\""
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 5729, __extension__ __PRETTY_FUNCTION__
))
5729 "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\""
, "llvm/lib/CodeGen/CodeGenPrepare.cpp", 5729, __extension__ __PRETTY_FUNCTION__
))
;
5730
5731 // We would be able to merge only one extension in a load.
5732 // Therefore, if we have more than 1 new extension we heuristically
5733 // cut this search path, because it means we degrade the code quality.
5734 // With exactly 2, the transformation is neutral, because we will merge
5735 // one extension but leave one. However, we optimistically keep going,
5736 // because the new extension may be removed too.
5737 long long TotalCreatedInstsCost = CreatedInstsCost + NewCreatedInstsCost;
5738 // FIXME: It would be possible to propagate a negative value instead of
5739 // conservatively ceiling it to 0.