Bug Summary

File:lib/Transforms/IPO/SampleProfile.cpp
Warning:line 710, column 10
Called C++ object pointer is null

Annotated Source Code

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clang -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name SampleProfile.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-eagerly-assume -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -mrelocation-model pic -pic-level 2 -mthread-model posix -fmath-errno -masm-verbose -mconstructor-aliases -munwind-tables -fuse-init-array -target-cpu x86-64 -dwarf-column-info -debugger-tuning=gdb -momit-leaf-frame-pointer -ffunction-sections -fdata-sections -resource-dir /usr/lib/llvm-7/lib/clang/7.0.0 -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-7~svn337490/build-llvm/lib/Transforms/IPO -I /build/llvm-toolchain-snapshot-7~svn337490/lib/Transforms/IPO -I /build/llvm-toolchain-snapshot-7~svn337490/build-llvm/include -I /build/llvm-toolchain-snapshot-7~svn337490/include -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/8/../../../../include/c++/8 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/8/../../../../include/x86_64-linux-gnu/c++/8 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/8/../../../../include/x86_64-linux-gnu/c++/8 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/8/../../../../include/c++/8/backward -internal-isystem /usr/include/clang/7.0.0/include/ -internal-isystem /usr/local/include -internal-isystem /usr/lib/llvm-7/lib/clang/7.0.0/include -internal-externc-isystem /usr/lib/gcc/x86_64-linux-gnu/8/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-comment -std=c++11 -fdeprecated-macro -fdebug-compilation-dir /build/llvm-toolchain-snapshot-7~svn337490/build-llvm/lib/Transforms/IPO -ferror-limit 19 -fmessage-length 0 -fvisibility-inlines-hidden -fobjc-runtime=gcc -fdiagnostics-show-option -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -o /tmp/scan-build-2018-07-20-043646-20380-1 -x c++ /build/llvm-toolchain-snapshot-7~svn337490/lib/Transforms/IPO/SampleProfile.cpp -faddrsig
1//===- SampleProfile.cpp - Incorporate sample profiles into the IR --------===//
2//
3// The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file implements the SampleProfileLoader transformation. This pass
11// reads a profile file generated by a sampling profiler (e.g. Linux Perf -
12// http://perf.wiki.kernel.org/) and generates IR metadata to reflect the
13// profile information in the given profile.
14//
15// This pass generates branch weight annotations on the IR:
16//
17// - prof: Represents branch weights. This annotation is added to branches
18// to indicate the weights of each edge coming out of the branch.
19// The weight of each edge is the weight of the target block for
20// that edge. The weight of a block B is computed as the maximum
21// number of samples found in B.
22//
23//===----------------------------------------------------------------------===//
24
25#include "llvm/Transforms/IPO/SampleProfile.h"
26#include "llvm/ADT/ArrayRef.h"
27#include "llvm/ADT/DenseMap.h"
28#include "llvm/ADT/DenseSet.h"
29#include "llvm/ADT/None.h"
30#include "llvm/ADT/SmallPtrSet.h"
31#include "llvm/ADT/SmallSet.h"
32#include "llvm/ADT/SmallVector.h"
33#include "llvm/ADT/StringMap.h"
34#include "llvm/ADT/StringRef.h"
35#include "llvm/ADT/Twine.h"
36#include "llvm/Analysis/AssumptionCache.h"
37#include "llvm/Analysis/InlineCost.h"
38#include "llvm/Analysis/LoopInfo.h"
39#include "llvm/Analysis/OptimizationRemarkEmitter.h"
40#include "llvm/Analysis/PostDominators.h"
41#include "llvm/Analysis/ProfileSummaryInfo.h"
42#include "llvm/Analysis/TargetTransformInfo.h"
43#include "llvm/IR/BasicBlock.h"
44#include "llvm/IR/CFG.h"
45#include "llvm/IR/CallSite.h"
46#include "llvm/IR/DebugInfoMetadata.h"
47#include "llvm/IR/DebugLoc.h"
48#include "llvm/IR/DiagnosticInfo.h"
49#include "llvm/IR/Dominators.h"
50#include "llvm/IR/Function.h"
51#include "llvm/IR/GlobalValue.h"
52#include "llvm/IR/InstrTypes.h"
53#include "llvm/IR/Instruction.h"
54#include "llvm/IR/Instructions.h"
55#include "llvm/IR/IntrinsicInst.h"
56#include "llvm/IR/LLVMContext.h"
57#include "llvm/IR/MDBuilder.h"
58#include "llvm/IR/Module.h"
59#include "llvm/IR/PassManager.h"
60#include "llvm/IR/ValueSymbolTable.h"
61#include "llvm/Pass.h"
62#include "llvm/ProfileData/InstrProf.h"
63#include "llvm/ProfileData/SampleProf.h"
64#include "llvm/ProfileData/SampleProfReader.h"
65#include "llvm/Support/Casting.h"
66#include "llvm/Support/CommandLine.h"
67#include "llvm/Support/Debug.h"
68#include "llvm/Support/ErrorHandling.h"
69#include "llvm/Support/ErrorOr.h"
70#include "llvm/Support/GenericDomTree.h"
71#include "llvm/Support/raw_ostream.h"
72#include "llvm/Transforms/IPO.h"
73#include "llvm/Transforms/Instrumentation.h"
74#include "llvm/Transforms/Utils/CallPromotionUtils.h"
75#include "llvm/Transforms/Utils/Cloning.h"
76#include <algorithm>
77#include <cassert>
78#include <cstdint>
79#include <functional>
80#include <limits>
81#include <map>
82#include <memory>
83#include <string>
84#include <system_error>
85#include <utility>
86#include <vector>
87
88using namespace llvm;
89using namespace sampleprof;
90using ProfileCount = Function::ProfileCount;
91#define DEBUG_TYPE"sample-profile" "sample-profile"
92
93// Command line option to specify the file to read samples from. This is
94// mainly used for debugging.
95static cl::opt<std::string> SampleProfileFile(
96 "sample-profile-file", cl::init(""), cl::value_desc("filename"),
97 cl::desc("Profile file loaded by -sample-profile"), cl::Hidden);
98
99static cl::opt<unsigned> SampleProfileMaxPropagateIterations(
100 "sample-profile-max-propagate-iterations", cl::init(100),
101 cl::desc("Maximum number of iterations to go through when propagating "
102 "sample block/edge weights through the CFG."));
103
104static cl::opt<unsigned> SampleProfileRecordCoverage(
105 "sample-profile-check-record-coverage", cl::init(0), cl::value_desc("N"),
106 cl::desc("Emit a warning if less than N% of records in the input profile "
107 "are matched to the IR."));
108
109static cl::opt<unsigned> SampleProfileSampleCoverage(
110 "sample-profile-check-sample-coverage", cl::init(0), cl::value_desc("N"),
111 cl::desc("Emit a warning if less than N% of samples in the input profile "
112 "are matched to the IR."));
113
114static cl::opt<bool> NoWarnSampleUnused(
115 "no-warn-sample-unused", cl::init(false), cl::Hidden,
116 cl::desc("Use this option to turn off/on warnings about function with "
117 "samples but without debug information to use those samples. "));
118
119namespace {
120
121using BlockWeightMap = DenseMap<const BasicBlock *, uint64_t>;
122using EquivalenceClassMap = DenseMap<const BasicBlock *, const BasicBlock *>;
123using Edge = std::pair<const BasicBlock *, const BasicBlock *>;
124using EdgeWeightMap = DenseMap<Edge, uint64_t>;
125using BlockEdgeMap =
126 DenseMap<const BasicBlock *, SmallVector<const BasicBlock *, 8>>;
127
128class SampleCoverageTracker {
129public:
130 SampleCoverageTracker() = default;
131
132 bool markSamplesUsed(const FunctionSamples *FS, uint32_t LineOffset,
133 uint32_t Discriminator, uint64_t Samples);
134 unsigned computeCoverage(unsigned Used, unsigned Total) const;
135 unsigned countUsedRecords(const FunctionSamples *FS,
136 ProfileSummaryInfo *PSI) const;
137 unsigned countBodyRecords(const FunctionSamples *FS,
138 ProfileSummaryInfo *PSI) const;
139 uint64_t getTotalUsedSamples() const { return TotalUsedSamples; }
140 uint64_t countBodySamples(const FunctionSamples *FS,
141 ProfileSummaryInfo *PSI) const;
142
143 void clear() {
144 SampleCoverage.clear();
145 TotalUsedSamples = 0;
146 }
147
148private:
149 using BodySampleCoverageMap = std::map<LineLocation, unsigned>;
150 using FunctionSamplesCoverageMap =
151 DenseMap<const FunctionSamples *, BodySampleCoverageMap>;
152
153 /// Coverage map for sampling records.
154 ///
155 /// This map keeps a record of sampling records that have been matched to
156 /// an IR instruction. This is used to detect some form of staleness in
157 /// profiles (see flag -sample-profile-check-coverage).
158 ///
159 /// Each entry in the map corresponds to a FunctionSamples instance. This is
160 /// another map that counts how many times the sample record at the
161 /// given location has been used.
162 FunctionSamplesCoverageMap SampleCoverage;
163
164 /// Number of samples used from the profile.
165 ///
166 /// When a sampling record is used for the first time, the samples from
167 /// that record are added to this accumulator. Coverage is later computed
168 /// based on the total number of samples available in this function and
169 /// its callsites.
170 ///
171 /// Note that this accumulator tracks samples used from a single function
172 /// and all the inlined callsites. Strictly, we should have a map of counters
173 /// keyed by FunctionSamples pointers, but these stats are cleared after
174 /// every function, so we just need to keep a single counter.
175 uint64_t TotalUsedSamples = 0;
176};
177
178/// Sample profile pass.
179///
180/// This pass reads profile data from the file specified by
181/// -sample-profile-file and annotates every affected function with the
182/// profile information found in that file.
183class SampleProfileLoader {
184public:
185 SampleProfileLoader(
186 StringRef Name, bool IsThinLTOPreLink,
187 std::function<AssumptionCache &(Function &)> GetAssumptionCache,
188 std::function<TargetTransformInfo &(Function &)> GetTargetTransformInfo)
189 : GetAC(std::move(GetAssumptionCache)),
190 GetTTI(std::move(GetTargetTransformInfo)), Filename(Name),
191 IsThinLTOPreLink(IsThinLTOPreLink) {}
192
193 bool doInitialization(Module &M);
194 bool runOnModule(Module &M, ModuleAnalysisManager *AM,
195 ProfileSummaryInfo *_PSI);
196
197 void dump() { Reader->dump(); }
198
199protected:
200 bool runOnFunction(Function &F, ModuleAnalysisManager *AM);
201 unsigned getFunctionLoc(Function &F);
202 bool emitAnnotations(Function &F);
203 ErrorOr<uint64_t> getInstWeight(const Instruction &I);
204 ErrorOr<uint64_t> getBlockWeight(const BasicBlock *BB);
205 const FunctionSamples *findCalleeFunctionSamples(const Instruction &I) const;
206 std::vector<const FunctionSamples *>
207 findIndirectCallFunctionSamples(const Instruction &I, uint64_t &Sum) const;
208 const FunctionSamples *findFunctionSamples(const Instruction &I) const;
209 bool inlineCallInstruction(Instruction *I);
210 bool inlineHotFunctions(Function &F,
211 DenseSet<GlobalValue::GUID> &InlinedGUIDs);
212 void printEdgeWeight(raw_ostream &OS, Edge E);
213 void printBlockWeight(raw_ostream &OS, const BasicBlock *BB) const;
214 void printBlockEquivalence(raw_ostream &OS, const BasicBlock *BB);
215 bool computeBlockWeights(Function &F);
216 void findEquivalenceClasses(Function &F);
217 template <bool IsPostDom>
218 void findEquivalencesFor(BasicBlock *BB1, ArrayRef<BasicBlock *> Descendants,
219 DominatorTreeBase<BasicBlock, IsPostDom> *DomTree);
220
221 void propagateWeights(Function &F);
222 uint64_t visitEdge(Edge E, unsigned *NumUnknownEdges, Edge *UnknownEdge);
223 void buildEdges(Function &F);
224 bool propagateThroughEdges(Function &F, bool UpdateBlockCount);
225 void computeDominanceAndLoopInfo(Function &F);
226 void clearFunctionData();
227
228 /// Map basic blocks to their computed weights.
229 ///
230 /// The weight of a basic block is defined to be the maximum
231 /// of all the instruction weights in that block.
232 BlockWeightMap BlockWeights;
233
234 /// Map edges to their computed weights.
235 ///
236 /// Edge weights are computed by propagating basic block weights in
237 /// SampleProfile::propagateWeights.
238 EdgeWeightMap EdgeWeights;
239
240 /// Set of visited blocks during propagation.
241 SmallPtrSet<const BasicBlock *, 32> VisitedBlocks;
242
243 /// Set of visited edges during propagation.
244 SmallSet<Edge, 32> VisitedEdges;
245
246 /// Equivalence classes for block weights.
247 ///
248 /// Two blocks BB1 and BB2 are in the same equivalence class if they
249 /// dominate and post-dominate each other, and they are in the same loop
250 /// nest. When this happens, the two blocks are guaranteed to execute
251 /// the same number of times.
252 EquivalenceClassMap EquivalenceClass;
253
254 /// Map from function name to Function *. Used to find the function from
255 /// the function name. If the function name contains suffix, additional
256 /// entry is added to map from the stripped name to the function if there
257 /// is one-to-one mapping.
258 StringMap<Function *> SymbolMap;
259
260 /// Dominance, post-dominance and loop information.
261 std::unique_ptr<DominatorTree> DT;
262 std::unique_ptr<PostDominatorTree> PDT;
263 std::unique_ptr<LoopInfo> LI;
264
265 std::function<AssumptionCache &(Function &)> GetAC;
266 std::function<TargetTransformInfo &(Function &)> GetTTI;
267
268 /// Predecessors for each basic block in the CFG.
269 BlockEdgeMap Predecessors;
270
271 /// Successors for each basic block in the CFG.
272 BlockEdgeMap Successors;
273
274 SampleCoverageTracker CoverageTracker;
275
276 /// Profile reader object.
277 std::unique_ptr<SampleProfileReader> Reader;
278
279 /// Samples collected for the body of this function.
280 FunctionSamples *Samples = nullptr;
281
282 /// Name of the profile file to load.
283 std::string Filename;
284
285 /// Flag indicating whether the profile input loaded successfully.
286 bool ProfileIsValid = false;
287
288 /// Flag indicating if the pass is invoked in ThinLTO compile phase.
289 ///
290 /// In this phase, in annotation, we should not promote indirect calls.
291 /// Instead, we will mark GUIDs that needs to be annotated to the function.
292 bool IsThinLTOPreLink;
293
294 /// Profile Summary Info computed from sample profile.
295 ProfileSummaryInfo *PSI = nullptr;
296
297 /// Total number of samples collected in this profile.
298 ///
299 /// This is the sum of all the samples collected in all the functions executed
300 /// at runtime.
301 uint64_t TotalCollectedSamples = 0;
302
303 /// Optimization Remark Emitter used to emit diagnostic remarks.
304 OptimizationRemarkEmitter *ORE = nullptr;
305};
306
307class SampleProfileLoaderLegacyPass : public ModulePass {
308public:
309 // Class identification, replacement for typeinfo
310 static char ID;
311
312 SampleProfileLoaderLegacyPass(StringRef Name = SampleProfileFile,
313 bool IsThinLTOPreLink = false)
314 : ModulePass(ID), SampleLoader(Name, IsThinLTOPreLink,
315 [&](Function &F) -> AssumptionCache & {
316 return ACT->getAssumptionCache(F);
317 },
318 [&](Function &F) -> TargetTransformInfo & {
319 return TTIWP->getTTI(F);
320 }) {
321 initializeSampleProfileLoaderLegacyPassPass(
322 *PassRegistry::getPassRegistry());
323 }
324
325 void dump() { SampleLoader.dump(); }
326
327 bool doInitialization(Module &M) override {
328 return SampleLoader.doInitialization(M);
329 }
330
331 StringRef getPassName() const override { return "Sample profile pass"; }
332 bool runOnModule(Module &M) override;
333
334 void getAnalysisUsage(AnalysisUsage &AU) const override {
335 AU.addRequired<AssumptionCacheTracker>();
336 AU.addRequired<TargetTransformInfoWrapperPass>();
337 AU.addRequired<ProfileSummaryInfoWrapperPass>();
338 }
339
340private:
341 SampleProfileLoader SampleLoader;
342 AssumptionCacheTracker *ACT = nullptr;
343 TargetTransformInfoWrapperPass *TTIWP = nullptr;
344};
345
346} // end anonymous namespace
347
348/// Return true if the given callsite is hot wrt to hot cutoff threshold.
349///
350/// Functions that were inlined in the original binary will be represented
351/// in the inline stack in the sample profile. If the profile shows that
352/// the original inline decision was "good" (i.e., the callsite is executed
353/// frequently), then we will recreate the inline decision and apply the
354/// profile from the inlined callsite.
355///
356/// To decide whether an inlined callsite is hot, we compare the callsite
357/// sample count with the hot cutoff computed by ProfileSummaryInfo, it is
358/// regarded as hot if the count is above the cutoff value.
359static bool callsiteIsHot(const FunctionSamples *CallsiteFS,
360 ProfileSummaryInfo *PSI) {
361 if (!CallsiteFS)
362 return false; // The callsite was not inlined in the original binary.
363
364 assert(PSI && "PSI is expected to be non null")(static_cast <bool> (PSI && "PSI is expected to be non null"
) ? void (0) : __assert_fail ("PSI && \"PSI is expected to be non null\""
, "/build/llvm-toolchain-snapshot-7~svn337490/lib/Transforms/IPO/SampleProfile.cpp"
, 364, __extension__ __PRETTY_FUNCTION__))
;
365 uint64_t CallsiteTotalSamples = CallsiteFS->getTotalSamples();
366 return PSI->isHotCount(CallsiteTotalSamples);
367}
368
369/// Mark as used the sample record for the given function samples at
370/// (LineOffset, Discriminator).
371///
372/// \returns true if this is the first time we mark the given record.
373bool SampleCoverageTracker::markSamplesUsed(const FunctionSamples *FS,
374 uint32_t LineOffset,
375 uint32_t Discriminator,
376 uint64_t Samples) {
377 LineLocation Loc(LineOffset, Discriminator);
378 unsigned &Count = SampleCoverage[FS][Loc];
379 bool FirstTime = (++Count == 1);
380 if (FirstTime)
381 TotalUsedSamples += Samples;
382 return FirstTime;
383}
384
385/// Return the number of sample records that were applied from this profile.
386///
387/// This count does not include records from cold inlined callsites.
388unsigned
389SampleCoverageTracker::countUsedRecords(const FunctionSamples *FS,
390 ProfileSummaryInfo *PSI) const {
391 auto I = SampleCoverage.find(FS);
392
393 // The size of the coverage map for FS represents the number of records
394 // that were marked used at least once.
395 unsigned Count = (I != SampleCoverage.end()) ? I->second.size() : 0;
396
397 // If there are inlined callsites in this function, count the samples found
398 // in the respective bodies. However, do not bother counting callees with 0
399 // total samples, these are callees that were never invoked at runtime.
400 for (const auto &I : FS->getCallsiteSamples())
401 for (const auto &J : I.second) {
402 const FunctionSamples *CalleeSamples = &J.second;
403 if (callsiteIsHot(CalleeSamples, PSI))
404 Count += countUsedRecords(CalleeSamples, PSI);
405 }
406
407 return Count;
408}
409
410/// Return the number of sample records in the body of this profile.
411///
412/// This count does not include records from cold inlined callsites.
413unsigned
414SampleCoverageTracker::countBodyRecords(const FunctionSamples *FS,
415 ProfileSummaryInfo *PSI) const {
416 unsigned Count = FS->getBodySamples().size();
417
418 // Only count records in hot callsites.
419 for (const auto &I : FS->getCallsiteSamples())
420 for (const auto &J : I.second) {
421 const FunctionSamples *CalleeSamples = &J.second;
422 if (callsiteIsHot(CalleeSamples, PSI))
423 Count += countBodyRecords(CalleeSamples, PSI);
424 }
425
426 return Count;
427}
428
429/// Return the number of samples collected in the body of this profile.
430///
431/// This count does not include samples from cold inlined callsites.
432uint64_t
433SampleCoverageTracker::countBodySamples(const FunctionSamples *FS,
434 ProfileSummaryInfo *PSI) const {
435 uint64_t Total = 0;
436 for (const auto &I : FS->getBodySamples())
437 Total += I.second.getSamples();
438
439 // Only count samples in hot callsites.
440 for (const auto &I : FS->getCallsiteSamples())
441 for (const auto &J : I.second) {
442 const FunctionSamples *CalleeSamples = &J.second;
443 if (callsiteIsHot(CalleeSamples, PSI))
444 Total += countBodySamples(CalleeSamples, PSI);
445 }
446
447 return Total;
448}
449
450/// Return the fraction of sample records used in this profile.
451///
452/// The returned value is an unsigned integer in the range 0-100 indicating
453/// the percentage of sample records that were used while applying this
454/// profile to the associated function.
455unsigned SampleCoverageTracker::computeCoverage(unsigned Used,
456 unsigned Total) const {
457 assert(Used <= Total &&(static_cast <bool> (Used <= Total && "number of used records cannot exceed the total number of records"
) ? void (0) : __assert_fail ("Used <= Total && \"number of used records cannot exceed the total number of records\""
, "/build/llvm-toolchain-snapshot-7~svn337490/lib/Transforms/IPO/SampleProfile.cpp"
, 458, __extension__ __PRETTY_FUNCTION__))
458 "number of used records cannot exceed the total number of records")(static_cast <bool> (Used <= Total && "number of used records cannot exceed the total number of records"
) ? void (0) : __assert_fail ("Used <= Total && \"number of used records cannot exceed the total number of records\""
, "/build/llvm-toolchain-snapshot-7~svn337490/lib/Transforms/IPO/SampleProfile.cpp"
, 458, __extension__ __PRETTY_FUNCTION__))
;
459 return Total > 0 ? Used * 100 / Total : 100;
460}
461
462/// Clear all the per-function data used to load samples and propagate weights.
463void SampleProfileLoader::clearFunctionData() {
464 BlockWeights.clear();
465 EdgeWeights.clear();
466 VisitedBlocks.clear();
467 VisitedEdges.clear();
468 EquivalenceClass.clear();
469 DT = nullptr;
470 PDT = nullptr;
471 LI = nullptr;
472 Predecessors.clear();
473 Successors.clear();
474 CoverageTracker.clear();
475}
476
477#ifndef NDEBUG
478/// Print the weight of edge \p E on stream \p OS.
479///
480/// \param OS Stream to emit the output to.
481/// \param E Edge to print.
482void SampleProfileLoader::printEdgeWeight(raw_ostream &OS, Edge E) {
483 OS << "weight[" << E.first->getName() << "->" << E.second->getName()
484 << "]: " << EdgeWeights[E] << "\n";
485}
486
487/// Print the equivalence class of block \p BB on stream \p OS.
488///
489/// \param OS Stream to emit the output to.
490/// \param BB Block to print.
491void SampleProfileLoader::printBlockEquivalence(raw_ostream &OS,
492 const BasicBlock *BB) {
493 const BasicBlock *Equiv = EquivalenceClass[BB];
494 OS << "equivalence[" << BB->getName()
495 << "]: " << ((Equiv) ? EquivalenceClass[BB]->getName() : "NONE") << "\n";
496}
497
498/// Print the weight of block \p BB on stream \p OS.
499///
500/// \param OS Stream to emit the output to.
501/// \param BB Block to print.
502void SampleProfileLoader::printBlockWeight(raw_ostream &OS,
503 const BasicBlock *BB) const {
504 const auto &I = BlockWeights.find(BB);
505 uint64_t W = (I == BlockWeights.end() ? 0 : I->second);
506 OS << "weight[" << BB->getName() << "]: " << W << "\n";
507}
508#endif
509
510/// Get the weight for an instruction.
511///
512/// The "weight" of an instruction \p Inst is the number of samples
513/// collected on that instruction at runtime. To retrieve it, we
514/// need to compute the line number of \p Inst relative to the start of its
515/// function. We use HeaderLineno to compute the offset. We then
516/// look up the samples collected for \p Inst using BodySamples.
517///
518/// \param Inst Instruction to query.
519///
520/// \returns the weight of \p Inst.
521ErrorOr<uint64_t> SampleProfileLoader::getInstWeight(const Instruction &Inst) {
522 const DebugLoc &DLoc = Inst.getDebugLoc();
523 if (!DLoc)
2
Assuming the condition is false
3
Taking false branch
9
Assuming the condition is false
10
Taking false branch
524 return std::error_code();
525
526 const FunctionSamples *FS = findFunctionSamples(Inst);
11
Calling 'SampleProfileLoader::findFunctionSamples'
527 if (!FS)
4
Assuming 'FS' is null
5
Taking true branch
528 return std::error_code();
529
530 // Ignore all intrinsics and branch instructions.
531 // Branch instruction usually contains debug info from sources outside of
532 // the residing basic block, thus we ignore them during annotation.
533 if (isa<BranchInst>(Inst) || isa<IntrinsicInst>(Inst))
534 return std::error_code();
535
536 // If a direct call/invoke instruction is inlined in profile
537 // (findCalleeFunctionSamples returns non-empty result), but not inlined here,
538 // it means that the inlined callsite has no sample, thus the call
539 // instruction should have 0 count.
540 if ((isa<CallInst>(Inst) || isa<InvokeInst>(Inst)) &&
541 !ImmutableCallSite(&Inst).isIndirectCall() &&
542 findCalleeFunctionSamples(Inst))
543 return 0;
544
545 const DILocation *DIL = DLoc;
546 uint32_t LineOffset = FunctionSamples::getOffset(DIL);
547 uint32_t Discriminator = DIL->getBaseDiscriminator();
548 ErrorOr<uint64_t> R = FS->findSamplesAt(LineOffset, Discriminator);
549 if (R) {
550 bool FirstMark =
551 CoverageTracker.markSamplesUsed(FS, LineOffset, Discriminator, R.get());
552 if (FirstMark) {
553 ORE->emit([&]() {
554 OptimizationRemarkAnalysis Remark(DEBUG_TYPE"sample-profile", "AppliedSamples", &Inst);
555 Remark << "Applied " << ore::NV("NumSamples", *R);
556 Remark << " samples from profile (offset: ";
557 Remark << ore::NV("LineOffset", LineOffset);
558 if (Discriminator) {
559 Remark << ".";
560 Remark << ore::NV("Discriminator", Discriminator);
561 }
562 Remark << ")";
563 return Remark;
564 });
565 }
566 LLVM_DEBUG(dbgs() << " " << DLoc.getLine() << "."do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { dbgs() << " " << DLoc.getLine
() << "." << DIL->getBaseDiscriminator() <<
":" << Inst << " (line offset: " << LineOffset
<< "." << DIL->getBaseDiscriminator() <<
" - weight: " << R.get() << ")\n"; } } while (false
)
567 << DIL->getBaseDiscriminator() << ":" << Instdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { dbgs() << " " << DLoc.getLine
() << "." << DIL->getBaseDiscriminator() <<
":" << Inst << " (line offset: " << LineOffset
<< "." << DIL->getBaseDiscriminator() <<
" - weight: " << R.get() << ")\n"; } } while (false
)
568 << " (line offset: " << LineOffset << "."do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { dbgs() << " " << DLoc.getLine
() << "." << DIL->getBaseDiscriminator() <<
":" << Inst << " (line offset: " << LineOffset
<< "." << DIL->getBaseDiscriminator() <<
" - weight: " << R.get() << ")\n"; } } while (false
)
569 << DIL->getBaseDiscriminator() << " - weight: " << R.get()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { dbgs() << " " << DLoc.getLine
() << "." << DIL->getBaseDiscriminator() <<
":" << Inst << " (line offset: " << LineOffset
<< "." << DIL->getBaseDiscriminator() <<
" - weight: " << R.get() << ")\n"; } } while (false
)
570 << ")\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { dbgs() << " " << DLoc.getLine
() << "." << DIL->getBaseDiscriminator() <<
":" << Inst << " (line offset: " << LineOffset
<< "." << DIL->getBaseDiscriminator() <<
" - weight: " << R.get() << ")\n"; } } while (false
)
;
571 }
572 return R;
573}
574
575/// Compute the weight of a basic block.
576///
577/// The weight of basic block \p BB is the maximum weight of all the
578/// instructions in BB.
579///
580/// \param BB The basic block to query.
581///
582/// \returns the weight for \p BB.
583ErrorOr<uint64_t> SampleProfileLoader::getBlockWeight(const BasicBlock *BB) {
584 uint64_t Max = 0;
585 bool HasWeight = false;
586 for (auto &I : BB->getInstList()) {
587 const ErrorOr<uint64_t> &R = getInstWeight(I);
1
Calling 'SampleProfileLoader::getInstWeight'
6
Returning from 'SampleProfileLoader::getInstWeight'
8
Calling 'SampleProfileLoader::getInstWeight'
588 if (R) {
7
Taking false branch
589 Max = std::max(Max, R.get());
590 HasWeight = true;
591 }
592 }
593 return HasWeight ? ErrorOr<uint64_t>(Max) : std::error_code();
594}
595
596/// Compute and store the weights of every basic block.
597///
598/// This populates the BlockWeights map by computing
599/// the weights of every basic block in the CFG.
600///
601/// \param F The function to query.
602bool SampleProfileLoader::computeBlockWeights(Function &F) {
603 bool Changed = false;
604 LLVM_DEBUG(dbgs() << "Block weights\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { dbgs() << "Block weights\n"; } } while
(false)
;
605 for (const auto &BB : F) {
606 ErrorOr<uint64_t> Weight = getBlockWeight(&BB);
607 if (Weight) {
608 BlockWeights[&BB] = Weight.get();
609 VisitedBlocks.insert(&BB);
610 Changed = true;
611 }
612 LLVM_DEBUG(printBlockWeight(dbgs(), &BB))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { printBlockWeight(dbgs(), &BB); } } while
(false)
;
613 }
614
615 return Changed;
616}
617
618/// Get the FunctionSamples for a call instruction.
619///
620/// The FunctionSamples of a call/invoke instruction \p Inst is the inlined
621/// instance in which that call instruction is calling to. It contains
622/// all samples that resides in the inlined instance. We first find the
623/// inlined instance in which the call instruction is from, then we
624/// traverse its children to find the callsite with the matching
625/// location.
626///
627/// \param Inst Call/Invoke instruction to query.
628///
629/// \returns The FunctionSamples pointer to the inlined instance.
630const FunctionSamples *
631SampleProfileLoader::findCalleeFunctionSamples(const Instruction &Inst) const {
632 const DILocation *DIL = Inst.getDebugLoc();
633 if (!DIL) {
634 return nullptr;
635 }
636
637 StringRef CalleeName;
638 if (const CallInst *CI = dyn_cast<CallInst>(&Inst))
639 if (Function *Callee = CI->getCalledFunction())
640 CalleeName = Callee->getName();
641
642 const FunctionSamples *FS = findFunctionSamples(Inst);
643 if (FS == nullptr)
644 return nullptr;
645
646 std::string CalleeGUID;
647 CalleeName = getRepInFormat(CalleeName, Reader->getFormat(), CalleeGUID);
648 return FS->findFunctionSamplesAt(LineLocation(FunctionSamples::getOffset(DIL),
649 DIL->getBaseDiscriminator()),
650 CalleeName);
651}
652
653/// Returns a vector of FunctionSamples that are the indirect call targets
654/// of \p Inst. The vector is sorted by the total number of samples. Stores
655/// the total call count of the indirect call in \p Sum.
656std::vector<const FunctionSamples *>
657SampleProfileLoader::findIndirectCallFunctionSamples(
658 const Instruction &Inst, uint64_t &Sum) const {
659 const DILocation *DIL = Inst.getDebugLoc();
660 std::vector<const FunctionSamples *> R;
661
662 if (!DIL) {
663 return R;
664 }
665
666 const FunctionSamples *FS = findFunctionSamples(Inst);
667 if (FS == nullptr)
668 return R;
669
670 uint32_t LineOffset = FunctionSamples::getOffset(DIL);
671 uint32_t Discriminator = DIL->getBaseDiscriminator();
672
673 auto T = FS->findCallTargetMapAt(LineOffset, Discriminator);
674 Sum = 0;
675 if (T)
676 for (const auto &T_C : T.get())
677 Sum += T_C.second;
678 if (const FunctionSamplesMap *M = FS->findFunctionSamplesMapAt(LineLocation(
679 FunctionSamples::getOffset(DIL), DIL->getBaseDiscriminator()))) {
680 if (M->empty())
681 return R;
682 for (const auto &NameFS : *M) {
683 Sum += NameFS.second.getEntrySamples();
684 R.push_back(&NameFS.second);
685 }
686 llvm::sort(R.begin(), R.end(),
687 [](const FunctionSamples *L, const FunctionSamples *R) {
688 return L->getEntrySamples() > R->getEntrySamples();
689 });
690 }
691 return R;
692}
693
694/// Get the FunctionSamples for an instruction.
695///
696/// The FunctionSamples of an instruction \p Inst is the inlined instance
697/// in which that instruction is coming from. We traverse the inline stack
698/// of that instruction, and match it with the tree nodes in the profile.
699///
700/// \param Inst Instruction to query.
701///
702/// \returns the FunctionSamples pointer to the inlined instance.
703const FunctionSamples *
704SampleProfileLoader::findFunctionSamples(const Instruction &Inst) const {
705 SmallVector<std::pair<LineLocation, StringRef>, 10> S;
706 const DILocation *DIL = Inst.getDebugLoc();
707 if (!DIL)
12
Assuming 'DIL' is non-null
13
Taking false branch
708 return Samples;
709
710 return Samples->findFunctionSamples(DIL);
14
Called C++ object pointer is null
711}
712
713bool SampleProfileLoader::inlineCallInstruction(Instruction *I) {
714 assert(isa<CallInst>(I) || isa<InvokeInst>(I))(static_cast <bool> (isa<CallInst>(I) || isa<InvokeInst
>(I)) ? void (0) : __assert_fail ("isa<CallInst>(I) || isa<InvokeInst>(I)"
, "/build/llvm-toolchain-snapshot-7~svn337490/lib/Transforms/IPO/SampleProfile.cpp"
, 714, __extension__ __PRETTY_FUNCTION__))
;
715 CallSite CS(I);
716 Function *CalledFunction = CS.getCalledFunction();
717 assert(CalledFunction)(static_cast <bool> (CalledFunction) ? void (0) : __assert_fail
("CalledFunction", "/build/llvm-toolchain-snapshot-7~svn337490/lib/Transforms/IPO/SampleProfile.cpp"
, 717, __extension__ __PRETTY_FUNCTION__))
;
718 DebugLoc DLoc = I->getDebugLoc();
719 BasicBlock *BB = I->getParent();
720 InlineParams Params = getInlineParams();
721 Params.ComputeFullInlineCost = true;
722 // Checks if there is anything in the reachable portion of the callee at
723 // this callsite that makes this inlining potentially illegal. Need to
724 // set ComputeFullInlineCost, otherwise getInlineCost may return early
725 // when cost exceeds threshold without checking all IRs in the callee.
726 // The acutal cost does not matter because we only checks isNever() to
727 // see if it is legal to inline the callsite.
728 InlineCost Cost = getInlineCost(CS, Params, GetTTI(*CalledFunction), GetAC,
729 None, nullptr, nullptr);
730 if (Cost.isNever()) {
731 ORE->emit(OptimizationRemark(DEBUG_TYPE"sample-profile", "Not inline", DLoc, BB)
732 << "incompatible inlining");
733 return false;
734 }
735 InlineFunctionInfo IFI(nullptr, &GetAC);
736 if (InlineFunction(CS, IFI)) {
737 // The call to InlineFunction erases I, so we can't pass it here.
738 ORE->emit(OptimizationRemark(DEBUG_TYPE"sample-profile", "HotInline", DLoc, BB)
739 << "inlined hot callee '" << ore::NV("Callee", CalledFunction)
740 << "' into '" << ore::NV("Caller", BB->getParent()) << "'");
741 return true;
742 }
743 return false;
744}
745
746/// Iteratively inline hot callsites of a function.
747///
748/// Iteratively traverse all callsites of the function \p F, and find if
749/// the corresponding inlined instance exists and is hot in profile. If
750/// it is hot enough, inline the callsites and adds new callsites of the
751/// callee into the caller. If the call is an indirect call, first promote
752/// it to direct call. Each indirect call is limited with a single target.
753///
754/// \param F function to perform iterative inlining.
755/// \param InlinedGUIDs a set to be updated to include all GUIDs that are
756/// inlined in the profiled binary.
757///
758/// \returns True if there is any inline happened.
759bool SampleProfileLoader::inlineHotFunctions(
760 Function &F, DenseSet<GlobalValue::GUID> &InlinedGUIDs) {
761 DenseSet<Instruction *> PromotedInsns;
762 bool Changed = false;
763 bool isCompact = (Reader->getFormat() == SPF_Compact_Binary);
764 while (true) {
765 bool LocalChanged = false;
766 SmallVector<Instruction *, 10> CIS;
767 for (auto &BB : F) {
768 bool Hot = false;
769 SmallVector<Instruction *, 10> Candidates;
770 for (auto &I : BB.getInstList()) {
771 const FunctionSamples *FS = nullptr;
772 if ((isa<CallInst>(I) || isa<InvokeInst>(I)) &&
773 !isa<IntrinsicInst>(I) && (FS = findCalleeFunctionSamples(I))) {
774 Candidates.push_back(&I);
775 if (callsiteIsHot(FS, PSI))
776 Hot = true;
777 }
778 }
779 if (Hot) {
780 CIS.insert(CIS.begin(), Candidates.begin(), Candidates.end());
781 }
782 }
783 for (auto I : CIS) {
784 Function *CalledFunction = CallSite(I).getCalledFunction();
785 // Do not inline recursive calls.
786 if (CalledFunction == &F)
787 continue;
788 if (CallSite(I).isIndirectCall()) {
789 if (PromotedInsns.count(I))
790 continue;
791 uint64_t Sum;
792 for (const auto *FS : findIndirectCallFunctionSamples(*I, Sum)) {
793 if (IsThinLTOPreLink) {
794 FS->findInlinedFunctions(InlinedGUIDs, F.getParent(),
795 PSI->getOrCompHotCountThreshold(),
796 isCompact);
797 continue;
798 }
799 auto CalleeFunctionName = FS->getName();
800 // If it is a recursive call, we do not inline it as it could bloat
801 // the code exponentially. There is way to better handle this, e.g.
802 // clone the caller first, and inline the cloned caller if it is
803 // recursive. As llvm does not inline recursive calls, we will
804 // simply ignore it instead of handling it explicitly.
805 std::string FGUID;
806 auto Fname = getRepInFormat(F.getName(), Reader->getFormat(), FGUID);
807 if (CalleeFunctionName == Fname)
808 continue;
809
810 const char *Reason = "Callee function not available";
811 auto R = SymbolMap.find(CalleeFunctionName);
812 if (R != SymbolMap.end() && R->getValue() &&
813 !R->getValue()->isDeclaration() &&
814 R->getValue()->getSubprogram() &&
815 isLegalToPromote(CallSite(I), R->getValue(), &Reason)) {
816 uint64_t C = FS->getEntrySamples();
817 Instruction *DI =
818 pgo::promoteIndirectCall(I, R->getValue(), C, Sum, false, ORE);
819 Sum -= C;
820 PromotedInsns.insert(I);
821 // If profile mismatches, we should not attempt to inline DI.
822 if ((isa<CallInst>(DI) || isa<InvokeInst>(DI)) &&
823 inlineCallInstruction(DI))
824 LocalChanged = true;
825 } else {
826 LLVM_DEBUG(dbgs()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { dbgs() << "\nFailed to promote indirect call to "
<< CalleeFunctionName << " because " << Reason
<< "\n"; } } while (false)
827 << "\nFailed to promote indirect call to "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { dbgs() << "\nFailed to promote indirect call to "
<< CalleeFunctionName << " because " << Reason
<< "\n"; } } while (false)
828 << CalleeFunctionName << " because " << Reason << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { dbgs() << "\nFailed to promote indirect call to "
<< CalleeFunctionName << " because " << Reason
<< "\n"; } } while (false)
;
829 }
830 }
831 } else if (CalledFunction && CalledFunction->getSubprogram() &&
832 !CalledFunction->isDeclaration()) {
833 if (inlineCallInstruction(I))
834 LocalChanged = true;
835 } else if (IsThinLTOPreLink) {
836 findCalleeFunctionSamples(*I)->findInlinedFunctions(
837 InlinedGUIDs, F.getParent(), PSI->getOrCompHotCountThreshold(),
838 isCompact);
839 }
840 }
841 if (LocalChanged) {
842 Changed = true;
843 } else {
844 break;
845 }
846 }
847 return Changed;
848}
849
850/// Find equivalence classes for the given block.
851///
852/// This finds all the blocks that are guaranteed to execute the same
853/// number of times as \p BB1. To do this, it traverses all the
854/// descendants of \p BB1 in the dominator or post-dominator tree.
855///
856/// A block BB2 will be in the same equivalence class as \p BB1 if
857/// the following holds:
858///
859/// 1- \p BB1 is a descendant of BB2 in the opposite tree. So, if BB2
860/// is a descendant of \p BB1 in the dominator tree, then BB2 should
861/// dominate BB1 in the post-dominator tree.
862///
863/// 2- Both BB2 and \p BB1 must be in the same loop.
864///
865/// For every block BB2 that meets those two requirements, we set BB2's
866/// equivalence class to \p BB1.
867///
868/// \param BB1 Block to check.
869/// \param Descendants Descendants of \p BB1 in either the dom or pdom tree.
870/// \param DomTree Opposite dominator tree. If \p Descendants is filled
871/// with blocks from \p BB1's dominator tree, then
872/// this is the post-dominator tree, and vice versa.
873template <bool IsPostDom>
874void SampleProfileLoader::findEquivalencesFor(
875 BasicBlock *BB1, ArrayRef<BasicBlock *> Descendants,
876 DominatorTreeBase<BasicBlock, IsPostDom> *DomTree) {
877 const BasicBlock *EC = EquivalenceClass[BB1];
878 uint64_t Weight = BlockWeights[EC];
879 for (const auto *BB2 : Descendants) {
880 bool IsDomParent = DomTree->dominates(BB2, BB1);
881 bool IsInSameLoop = LI->getLoopFor(BB1) == LI->getLoopFor(BB2);
882 if (BB1 != BB2 && IsDomParent && IsInSameLoop) {
883 EquivalenceClass[BB2] = EC;
884 // If BB2 is visited, then the entire EC should be marked as visited.
885 if (VisitedBlocks.count(BB2)) {
886 VisitedBlocks.insert(EC);
887 }
888
889 // If BB2 is heavier than BB1, make BB2 have the same weight
890 // as BB1.
891 //
892 // Note that we don't worry about the opposite situation here
893 // (when BB2 is lighter than BB1). We will deal with this
894 // during the propagation phase. Right now, we just want to
895 // make sure that BB1 has the largest weight of all the
896 // members of its equivalence set.
897 Weight = std::max(Weight, BlockWeights[BB2]);
898 }
899 }
900 if (EC == &EC->getParent()->getEntryBlock()) {
901 BlockWeights[EC] = Samples->getHeadSamples() + 1;
902 } else {
903 BlockWeights[EC] = Weight;
904 }
905}
906
907/// Find equivalence classes.
908///
909/// Since samples may be missing from blocks, we can fill in the gaps by setting
910/// the weights of all the blocks in the same equivalence class to the same
911/// weight. To compute the concept of equivalence, we use dominance and loop
912/// information. Two blocks B1 and B2 are in the same equivalence class if B1
913/// dominates B2, B2 post-dominates B1 and both are in the same loop.
914///
915/// \param F The function to query.
916void SampleProfileLoader::findEquivalenceClasses(Function &F) {
917 SmallVector<BasicBlock *, 8> DominatedBBs;
918 LLVM_DEBUG(dbgs() << "\nBlock equivalence classes\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { dbgs() << "\nBlock equivalence classes\n"
; } } while (false)
;
919 // Find equivalence sets based on dominance and post-dominance information.
920 for (auto &BB : F) {
921 BasicBlock *BB1 = &BB;
922
923 // Compute BB1's equivalence class once.
924 if (EquivalenceClass.count(BB1)) {
925 LLVM_DEBUG(printBlockEquivalence(dbgs(), BB1))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { printBlockEquivalence(dbgs(), BB1); } }
while (false)
;
926 continue;
927 }
928
929 // By default, blocks are in their own equivalence class.
930 EquivalenceClass[BB1] = BB1;
931
932 // Traverse all the blocks dominated by BB1. We are looking for
933 // every basic block BB2 such that:
934 //
935 // 1- BB1 dominates BB2.
936 // 2- BB2 post-dominates BB1.
937 // 3- BB1 and BB2 are in the same loop nest.
938 //
939 // If all those conditions hold, it means that BB2 is executed
940 // as many times as BB1, so they are placed in the same equivalence
941 // class by making BB2's equivalence class be BB1.
942 DominatedBBs.clear();
943 DT->getDescendants(BB1, DominatedBBs);
944 findEquivalencesFor(BB1, DominatedBBs, PDT.get());
945
946 LLVM_DEBUG(printBlockEquivalence(dbgs(), BB1))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { printBlockEquivalence(dbgs(), BB1); } }
while (false)
;
947 }
948
949 // Assign weights to equivalence classes.
950 //
951 // All the basic blocks in the same equivalence class will execute
952 // the same number of times. Since we know that the head block in
953 // each equivalence class has the largest weight, assign that weight
954 // to all the blocks in that equivalence class.
955 LLVM_DEBUG(do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { dbgs() << "\nAssign the same weight to all blocks in the same class\n"
; } } while (false)
956 dbgs() << "\nAssign the same weight to all blocks in the same class\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { dbgs() << "\nAssign the same weight to all blocks in the same class\n"
; } } while (false)
;
957 for (auto &BI : F) {
958 const BasicBlock *BB = &BI;
959 const BasicBlock *EquivBB = EquivalenceClass[BB];
960 if (BB != EquivBB)
961 BlockWeights[BB] = BlockWeights[EquivBB];
962 LLVM_DEBUG(printBlockWeight(dbgs(), BB))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { printBlockWeight(dbgs(), BB); } } while
(false)
;
963 }
964}
965
966/// Visit the given edge to decide if it has a valid weight.
967///
968/// If \p E has not been visited before, we copy to \p UnknownEdge
969/// and increment the count of unknown edges.
970///
971/// \param E Edge to visit.
972/// \param NumUnknownEdges Current number of unknown edges.
973/// \param UnknownEdge Set if E has not been visited before.
974///
975/// \returns E's weight, if known. Otherwise, return 0.
976uint64_t SampleProfileLoader::visitEdge(Edge E, unsigned *NumUnknownEdges,
977 Edge *UnknownEdge) {
978 if (!VisitedEdges.count(E)) {
979 (*NumUnknownEdges)++;
980 *UnknownEdge = E;
981 return 0;
982 }
983
984 return EdgeWeights[E];
985}
986
987/// Propagate weights through incoming/outgoing edges.
988///
989/// If the weight of a basic block is known, and there is only one edge
990/// with an unknown weight, we can calculate the weight of that edge.
991///
992/// Similarly, if all the edges have a known count, we can calculate the
993/// count of the basic block, if needed.
994///
995/// \param F Function to process.
996/// \param UpdateBlockCount Whether we should update basic block counts that
997/// has already been annotated.
998///
999/// \returns True if new weights were assigned to edges or blocks.
1000bool SampleProfileLoader::propagateThroughEdges(Function &F,
1001 bool UpdateBlockCount) {
1002 bool Changed = false;
1003 LLVM_DEBUG(dbgs() << "\nPropagation through edges\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { dbgs() << "\nPropagation through edges\n"
; } } while (false)
;
1004 for (const auto &BI : F) {
1005 const BasicBlock *BB = &BI;
1006 const BasicBlock *EC = EquivalenceClass[BB];
1007
1008 // Visit all the predecessor and successor edges to determine
1009 // which ones have a weight assigned already. Note that it doesn't
1010 // matter that we only keep track of a single unknown edge. The
1011 // only case we are interested in handling is when only a single
1012 // edge is unknown (see setEdgeOrBlockWeight).
1013 for (unsigned i = 0; i < 2; i++) {
1014 uint64_t TotalWeight = 0;
1015 unsigned NumUnknownEdges = 0, NumTotalEdges = 0;
1016 Edge UnknownEdge, SelfReferentialEdge, SingleEdge;
1017
1018 if (i == 0) {
1019 // First, visit all predecessor edges.
1020 NumTotalEdges = Predecessors[BB].size();
1021 for (auto *Pred : Predecessors[BB]) {
1022 Edge E = std::make_pair(Pred, BB);
1023 TotalWeight += visitEdge(E, &NumUnknownEdges, &UnknownEdge);
1024 if (E.first == E.second)
1025 SelfReferentialEdge = E;
1026 }
1027 if (NumTotalEdges == 1) {
1028 SingleEdge = std::make_pair(Predecessors[BB][0], BB);
1029 }
1030 } else {
1031 // On the second round, visit all successor edges.
1032 NumTotalEdges = Successors[BB].size();
1033 for (auto *Succ : Successors[BB]) {
1034 Edge E = std::make_pair(BB, Succ);
1035 TotalWeight += visitEdge(E, &NumUnknownEdges, &UnknownEdge);
1036 }
1037 if (NumTotalEdges == 1) {
1038 SingleEdge = std::make_pair(BB, Successors[BB][0]);
1039 }
1040 }
1041
1042 // After visiting all the edges, there are three cases that we
1043 // can handle immediately:
1044 //
1045 // - All the edge weights are known (i.e., NumUnknownEdges == 0).
1046 // In this case, we simply check that the sum of all the edges
1047 // is the same as BB's weight. If not, we change BB's weight
1048 // to match. Additionally, if BB had not been visited before,
1049 // we mark it visited.
1050 //
1051 // - Only one edge is unknown and BB has already been visited.
1052 // In this case, we can compute the weight of the edge by
1053 // subtracting the total block weight from all the known
1054 // edge weights. If the edges weight more than BB, then the
1055 // edge of the last remaining edge is set to zero.
1056 //
1057 // - There exists a self-referential edge and the weight of BB is
1058 // known. In this case, this edge can be based on BB's weight.
1059 // We add up all the other known edges and set the weight on
1060 // the self-referential edge as we did in the previous case.
1061 //
1062 // In any other case, we must continue iterating. Eventually,
1063 // all edges will get a weight, or iteration will stop when
1064 // it reaches SampleProfileMaxPropagateIterations.
1065 if (NumUnknownEdges <= 1) {
1066 uint64_t &BBWeight = BlockWeights[EC];
1067 if (NumUnknownEdges == 0) {
1068 if (!VisitedBlocks.count(EC)) {
1069 // If we already know the weight of all edges, the weight of the
1070 // basic block can be computed. It should be no larger than the sum
1071 // of all edge weights.
1072 if (TotalWeight > BBWeight) {
1073 BBWeight = TotalWeight;
1074 Changed = true;
1075 LLVM_DEBUG(dbgs() << "All edge weights for " << BB->getName()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { dbgs() << "All edge weights for "
<< BB->getName() << " known. Set weight for block: "
; printBlockWeight(dbgs(), BB);; } } while (false)
1076 << " known. Set weight for block: ";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { dbgs() << "All edge weights for "
<< BB->getName() << " known. Set weight for block: "
; printBlockWeight(dbgs(), BB);; } } while (false)
1077 printBlockWeight(dbgs(), BB);)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { dbgs() << "All edge weights for "
<< BB->getName() << " known. Set weight for block: "
; printBlockWeight(dbgs(), BB);; } } while (false)
;
1078 }
1079 } else if (NumTotalEdges == 1 &&
1080 EdgeWeights[SingleEdge] < BlockWeights[EC]) {
1081 // If there is only one edge for the visited basic block, use the
1082 // block weight to adjust edge weight if edge weight is smaller.
1083 EdgeWeights[SingleEdge] = BlockWeights[EC];
1084 Changed = true;
1085 }
1086 } else if (NumUnknownEdges == 1 && VisitedBlocks.count(EC)) {
1087 // If there is a single unknown edge and the block has been
1088 // visited, then we can compute E's weight.
1089 if (BBWeight >= TotalWeight)
1090 EdgeWeights[UnknownEdge] = BBWeight - TotalWeight;
1091 else
1092 EdgeWeights[UnknownEdge] = 0;
1093 const BasicBlock *OtherEC;
1094 if (i == 0)
1095 OtherEC = EquivalenceClass[UnknownEdge.first];
1096 else
1097 OtherEC = EquivalenceClass[UnknownEdge.second];
1098 // Edge weights should never exceed the BB weights it connects.
1099 if (VisitedBlocks.count(OtherEC) &&
1100 EdgeWeights[UnknownEdge] > BlockWeights[OtherEC])
1101 EdgeWeights[UnknownEdge] = BlockWeights[OtherEC];
1102 VisitedEdges.insert(UnknownEdge);
1103 Changed = true;
1104 LLVM_DEBUG(dbgs() << "Set weight for edge: ";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { dbgs() << "Set weight for edge: "
; printEdgeWeight(dbgs(), UnknownEdge); } } while (false)
1105 printEdgeWeight(dbgs(), UnknownEdge))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { dbgs() << "Set weight for edge: "
; printEdgeWeight(dbgs(), UnknownEdge); } } while (false)
;
1106 }
1107 } else if (VisitedBlocks.count(EC) && BlockWeights[EC] == 0) {
1108 // If a block Weights 0, all its in/out edges should weight 0.
1109 if (i == 0) {
1110 for (auto *Pred : Predecessors[BB]) {
1111 Edge E = std::make_pair(Pred, BB);
1112 EdgeWeights[E] = 0;
1113 VisitedEdges.insert(E);
1114 }
1115 } else {
1116 for (auto *Succ : Successors[BB]) {
1117 Edge E = std::make_pair(BB, Succ);
1118 EdgeWeights[E] = 0;
1119 VisitedEdges.insert(E);
1120 }
1121 }
1122 } else if (SelfReferentialEdge.first && VisitedBlocks.count(EC)) {
1123 uint64_t &BBWeight = BlockWeights[BB];
1124 // We have a self-referential edge and the weight of BB is known.
1125 if (BBWeight >= TotalWeight)
1126 EdgeWeights[SelfReferentialEdge] = BBWeight - TotalWeight;
1127 else
1128 EdgeWeights[SelfReferentialEdge] = 0;
1129 VisitedEdges.insert(SelfReferentialEdge);
1130 Changed = true;
1131 LLVM_DEBUG(dbgs() << "Set self-referential edge weight to: ";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { dbgs() << "Set self-referential edge weight to: "
; printEdgeWeight(dbgs(), SelfReferentialEdge); } } while (false
)
1132 printEdgeWeight(dbgs(), SelfReferentialEdge))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { dbgs() << "Set self-referential edge weight to: "
; printEdgeWeight(dbgs(), SelfReferentialEdge); } } while (false
)
;
1133 }
1134 if (UpdateBlockCount && !VisitedBlocks.count(EC) && TotalWeight > 0) {
1135 BlockWeights[EC] = TotalWeight;
1136 VisitedBlocks.insert(EC);
1137 Changed = true;
1138 }
1139 }
1140 }
1141
1142 return Changed;
1143}
1144
1145/// Build in/out edge lists for each basic block in the CFG.
1146///
1147/// We are interested in unique edges. If a block B1 has multiple
1148/// edges to another block B2, we only add a single B1->B2 edge.
1149void SampleProfileLoader::buildEdges(Function &F) {
1150 for (auto &BI : F) {
1151 BasicBlock *B1 = &BI;
1152
1153 // Add predecessors for B1.
1154 SmallPtrSet<BasicBlock *, 16> Visited;
1155 if (!Predecessors[B1].empty())
1156 llvm_unreachable("Found a stale predecessors list in a basic block.")::llvm::llvm_unreachable_internal("Found a stale predecessors list in a basic block."
, "/build/llvm-toolchain-snapshot-7~svn337490/lib/Transforms/IPO/SampleProfile.cpp"
, 1156)
;
1157 for (pred_iterator PI = pred_begin(B1), PE = pred_end(B1); PI != PE; ++PI) {
1158 BasicBlock *B2 = *PI;
1159 if (Visited.insert(B2).second)
1160 Predecessors[B1].push_back(B2);
1161 }
1162
1163 // Add successors for B1.
1164 Visited.clear();
1165 if (!Successors[B1].empty())
1166 llvm_unreachable("Found a stale successors list in a basic block.")::llvm::llvm_unreachable_internal("Found a stale successors list in a basic block."
, "/build/llvm-toolchain-snapshot-7~svn337490/lib/Transforms/IPO/SampleProfile.cpp"
, 1166)
;
1167 for (succ_iterator SI = succ_begin(B1), SE = succ_end(B1); SI != SE; ++SI) {
1168 BasicBlock *B2 = *SI;
1169 if (Visited.insert(B2).second)
1170 Successors[B1].push_back(B2);
1171 }
1172 }
1173}
1174
1175/// Returns the sorted CallTargetMap \p M by count in descending order.
1176static SmallVector<InstrProfValueData, 2> SortCallTargets(
1177 const SampleRecord::CallTargetMap &M) {
1178 SmallVector<InstrProfValueData, 2> R;
1179 for (auto I = M.begin(); I != M.end(); ++I)
1180 R.push_back({Function::getGUID(I->getKey()), I->getValue()});
1181 llvm::sort(R.begin(), R.end(),
1182 [](const InstrProfValueData &L, const InstrProfValueData &R) {
1183 if (L.Count == R.Count)
1184 return L.Value > R.Value;
1185 else
1186 return L.Count > R.Count;
1187 });
1188 return R;
1189}
1190
1191/// Propagate weights into edges
1192///
1193/// The following rules are applied to every block BB in the CFG:
1194///
1195/// - If BB has a single predecessor/successor, then the weight
1196/// of that edge is the weight of the block.
1197///
1198/// - If all incoming or outgoing edges are known except one, and the
1199/// weight of the block is already known, the weight of the unknown
1200/// edge will be the weight of the block minus the sum of all the known
1201/// edges. If the sum of all the known edges is larger than BB's weight,
1202/// we set the unknown edge weight to zero.
1203///
1204/// - If there is a self-referential edge, and the weight of the block is
1205/// known, the weight for that edge is set to the weight of the block
1206/// minus the weight of the other incoming edges to that block (if
1207/// known).
1208void SampleProfileLoader::propagateWeights(Function &F) {
1209 bool Changed = true;
1210 unsigned I = 0;
1211
1212 // If BB weight is larger than its corresponding loop's header BB weight,
1213 // use the BB weight to replace the loop header BB weight.
1214 for (auto &BI : F) {
1215 BasicBlock *BB = &BI;
1216 Loop *L = LI->getLoopFor(BB);
1217 if (!L) {
1218 continue;
1219 }
1220 BasicBlock *Header = L->getHeader();
1221 if (Header && BlockWeights[BB] > BlockWeights[Header]) {
1222 BlockWeights[Header] = BlockWeights[BB];
1223 }
1224 }
1225
1226 // Before propagation starts, build, for each block, a list of
1227 // unique predecessors and successors. This is necessary to handle
1228 // identical edges in multiway branches. Since we visit all blocks and all
1229 // edges of the CFG, it is cleaner to build these lists once at the start
1230 // of the pass.
1231 buildEdges(F);
1232
1233 // Propagate until we converge or we go past the iteration limit.
1234 while (Changed && I++ < SampleProfileMaxPropagateIterations) {
1235 Changed = propagateThroughEdges(F, false);
1236 }
1237
1238 // The first propagation propagates BB counts from annotated BBs to unknown
1239 // BBs. The 2nd propagation pass resets edges weights, and use all BB weights
1240 // to propagate edge weights.
1241 VisitedEdges.clear();
1242 Changed = true;
1243 while (Changed && I++ < SampleProfileMaxPropagateIterations) {
1244 Changed = propagateThroughEdges(F, false);
1245 }
1246
1247 // The 3rd propagation pass allows adjust annotated BB weights that are
1248 // obviously wrong.
1249 Changed = true;
1250 while (Changed && I++ < SampleProfileMaxPropagateIterations) {
1251 Changed = propagateThroughEdges(F, true);
1252 }
1253
1254 // Generate MD_prof metadata for every branch instruction using the
1255 // edge weights computed during propagation.
1256 LLVM_DEBUG(dbgs() << "\nPropagation complete. Setting branch weights\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { dbgs() << "\nPropagation complete. Setting branch weights\n"
; } } while (false)
;
1257 LLVMContext &Ctx = F.getContext();
1258 MDBuilder MDB(Ctx);
1259 for (auto &BI : F) {
1260 BasicBlock *BB = &BI;
1261
1262 if (BlockWeights[BB]) {
1263 for (auto &I : BB->getInstList()) {
1264 if (!isa<CallInst>(I) && !isa<InvokeInst>(I))
1265 continue;
1266 CallSite CS(&I);
1267 if (!CS.getCalledFunction()) {
1268 const DebugLoc &DLoc = I.getDebugLoc();
1269 if (!DLoc)
1270 continue;
1271 const DILocation *DIL = DLoc;
1272 uint32_t LineOffset = FunctionSamples::getOffset(DIL);
1273 uint32_t Discriminator = DIL->getBaseDiscriminator();
1274
1275 const FunctionSamples *FS = findFunctionSamples(I);
1276 if (!FS)
1277 continue;
1278 auto T = FS->findCallTargetMapAt(LineOffset, Discriminator);
1279 if (!T || T.get().empty())
1280 continue;
1281 SmallVector<InstrProfValueData, 2> SortedCallTargets =
1282 SortCallTargets(T.get());
1283 uint64_t Sum;
1284 findIndirectCallFunctionSamples(I, Sum);
1285 annotateValueSite(*I.getParent()->getParent()->getParent(), I,
1286 SortedCallTargets, Sum, IPVK_IndirectCallTarget,
1287 SortedCallTargets.size());
1288 } else if (!dyn_cast<IntrinsicInst>(&I)) {
1289 SmallVector<uint32_t, 1> Weights;
1290 Weights.push_back(BlockWeights[BB]);
1291 I.setMetadata(LLVMContext::MD_prof, MDB.createBranchWeights(Weights));
1292 }
1293 }
1294 }
1295 TerminatorInst *TI = BB->getTerminator();
1296 if (TI->getNumSuccessors() == 1)
1297 continue;
1298 if (!isa<BranchInst>(TI) && !isa<SwitchInst>(TI))
1299 continue;
1300
1301 DebugLoc BranchLoc = TI->getDebugLoc();
1302 LLVM_DEBUG(dbgs() << "\nGetting weights for branch at line "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { dbgs() << "\nGetting weights for branch at line "
<< ((BranchLoc) ? Twine(BranchLoc.getLine()) : Twine("<UNKNOWN LOCATION>"
)) << ".\n"; } } while (false)
1303 << ((BranchLoc) ? Twine(BranchLoc.getLine())do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { dbgs() << "\nGetting weights for branch at line "
<< ((BranchLoc) ? Twine(BranchLoc.getLine()) : Twine("<UNKNOWN LOCATION>"
)) << ".\n"; } } while (false)
1304 : Twine("<UNKNOWN LOCATION>"))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { dbgs() << "\nGetting weights for branch at line "
<< ((BranchLoc) ? Twine(BranchLoc.getLine()) : Twine("<UNKNOWN LOCATION>"
)) << ".\n"; } } while (false)
1305 << ".\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { dbgs() << "\nGetting weights for branch at line "
<< ((BranchLoc) ? Twine(BranchLoc.getLine()) : Twine("<UNKNOWN LOCATION>"
)) << ".\n"; } } while (false)
;
1306 SmallVector<uint32_t, 4> Weights;
1307 uint32_t MaxWeight = 0;
1308 Instruction *MaxDestInst;
1309 for (unsigned I = 0; I < TI->getNumSuccessors(); ++I) {
1310 BasicBlock *Succ = TI->getSuccessor(I);
1311 Edge E = std::make_pair(BB, Succ);
1312 uint64_t Weight = EdgeWeights[E];
1313 LLVM_DEBUG(dbgs() << "\t"; printEdgeWeight(dbgs(), E))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { dbgs() << "\t"; printEdgeWeight(dbgs
(), E); } } while (false)
;
1314 // Use uint32_t saturated arithmetic to adjust the incoming weights,
1315 // if needed. Sample counts in profiles are 64-bit unsigned values,
1316 // but internally branch weights are expressed as 32-bit values.
1317 if (Weight > std::numeric_limits<uint32_t>::max()) {
1318 LLVM_DEBUG(dbgs() << " (saturated due to uint32_t overflow)")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { dbgs() << " (saturated due to uint32_t overflow)"
; } } while (false)
;
1319 Weight = std::numeric_limits<uint32_t>::max();
1320 }
1321 // Weight is added by one to avoid propagation errors introduced by
1322 // 0 weights.
1323 Weights.push_back(static_cast<uint32_t>(Weight + 1));
1324 if (Weight != 0) {
1325 if (Weight > MaxWeight) {
1326 MaxWeight = Weight;
1327 MaxDestInst = Succ->getFirstNonPHIOrDbgOrLifetime();
1328 }
1329 }
1330 }
1331
1332 uint64_t TempWeight;
1333 // Only set weights if there is at least one non-zero weight.
1334 // In any other case, let the analyzer set weights.
1335 // Do not set weights if the weights are present. In ThinLTO, the profile
1336 // annotation is done twice. If the first annotation already set the
1337 // weights, the second pass does not need to set it.
1338 if (MaxWeight > 0 && !TI->extractProfTotalWeight(TempWeight)) {
1339 LLVM_DEBUG(dbgs() << "SUCCESS. Found non-zero weights.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { dbgs() << "SUCCESS. Found non-zero weights.\n"
; } } while (false)
;
1340 TI->setMetadata(LLVMContext::MD_prof,
1341 MDB.createBranchWeights(Weights));
1342 ORE->emit([&]() {
1343 return OptimizationRemark(DEBUG_TYPE"sample-profile", "PopularDest", MaxDestInst)
1344 << "most popular destination for conditional branches at "
1345 << ore::NV("CondBranchesLoc", BranchLoc);
1346 });
1347 } else {
1348 LLVM_DEBUG(dbgs() << "SKIPPED. All branch weights are zero.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { dbgs() << "SKIPPED. All branch weights are zero.\n"
; } } while (false)
;
1349 }
1350 }
1351}
1352
1353/// Get the line number for the function header.
1354///
1355/// This looks up function \p F in the current compilation unit and
1356/// retrieves the line number where the function is defined. This is
1357/// line 0 for all the samples read from the profile file. Every line
1358/// number is relative to this line.
1359///
1360/// \param F Function object to query.
1361///
1362/// \returns the line number where \p F is defined. If it returns 0,
1363/// it means that there is no debug information available for \p F.
1364unsigned SampleProfileLoader::getFunctionLoc(Function &F) {
1365 if (DISubprogram *S = F.getSubprogram())
1366 return S->getLine();
1367
1368 if (NoWarnSampleUnused)
1369 return 0;
1370
1371 // If the start of \p F is missing, emit a diagnostic to inform the user
1372 // about the missed opportunity.
1373 F.getContext().diagnose(DiagnosticInfoSampleProfile(
1374 "No debug information found in function " + F.getName() +
1375 ": Function profile not used",
1376 DS_Warning));
1377 return 0;
1378}
1379
1380void SampleProfileLoader::computeDominanceAndLoopInfo(Function &F) {
1381 DT.reset(new DominatorTree);
1382 DT->recalculate(F);
1383
1384 PDT.reset(new PostDominatorTree(F));
1385
1386 LI.reset(new LoopInfo);
1387 LI->analyze(*DT);
1388}
1389
1390/// Generate branch weight metadata for all branches in \p F.
1391///
1392/// Branch weights are computed out of instruction samples using a
1393/// propagation heuristic. Propagation proceeds in 3 phases:
1394///
1395/// 1- Assignment of block weights. All the basic blocks in the function
1396/// are initial assigned the same weight as their most frequently
1397/// executed instruction.
1398///
1399/// 2- Creation of equivalence classes. Since samples may be missing from
1400/// blocks, we can fill in the gaps by setting the weights of all the
1401/// blocks in the same equivalence class to the same weight. To compute
1402/// the concept of equivalence, we use dominance and loop information.
1403/// Two blocks B1 and B2 are in the same equivalence class if B1
1404/// dominates B2, B2 post-dominates B1 and both are in the same loop.
1405///
1406/// 3- Propagation of block weights into edges. This uses a simple
1407/// propagation heuristic. The following rules are applied to every
1408/// block BB in the CFG:
1409///
1410/// - If BB has a single predecessor/successor, then the weight
1411/// of that edge is the weight of the block.
1412///
1413/// - If all the edges are known except one, and the weight of the
1414/// block is already known, the weight of the unknown edge will
1415/// be the weight of the block minus the sum of all the known
1416/// edges. If the sum of all the known edges is larger than BB's weight,
1417/// we set the unknown edge weight to zero.
1418///
1419/// - If there is a self-referential edge, and the weight of the block is
1420/// known, the weight for that edge is set to the weight of the block
1421/// minus the weight of the other incoming edges to that block (if
1422/// known).
1423///
1424/// Since this propagation is not guaranteed to finalize for every CFG, we
1425/// only allow it to proceed for a limited number of iterations (controlled
1426/// by -sample-profile-max-propagate-iterations).
1427///
1428/// FIXME: Try to replace this propagation heuristic with a scheme
1429/// that is guaranteed to finalize. A work-list approach similar to
1430/// the standard value propagation algorithm used by SSA-CCP might
1431/// work here.
1432///
1433/// Once all the branch weights are computed, we emit the MD_prof
1434/// metadata on BB using the computed values for each of its branches.
1435///
1436/// \param F The function to query.
1437///
1438/// \returns true if \p F was modified. Returns false, otherwise.
1439bool SampleProfileLoader::emitAnnotations(Function &F) {
1440 bool Changed = false;
1441
1442 if (getFunctionLoc(F) == 0)
1443 return false;
1444
1445 LLVM_DEBUG(dbgs() << "Line number for the first instruction in "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { dbgs() << "Line number for the first instruction in "
<< F.getName() << ": " << getFunctionLoc(F
) << "\n"; } } while (false)
1446 << F.getName() << ": " << getFunctionLoc(F) << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { dbgs() << "Line number for the first instruction in "
<< F.getName() << ": " << getFunctionLoc(F
) << "\n"; } } while (false)
;
1447
1448 DenseSet<GlobalValue::GUID> InlinedGUIDs;
1449 Changed |= inlineHotFunctions(F, InlinedGUIDs);
1450
1451 // Compute basic block weights.
1452 Changed |= computeBlockWeights(F);
1453
1454 if (Changed) {
1455 // Add an entry count to the function using the samples gathered at the
1456 // function entry.
1457 // Sets the GUIDs that are inlined in the profiled binary. This is used
1458 // for ThinLink to make correct liveness analysis, and also make the IR
1459 // match the profiled binary before annotation.
1460 F.setEntryCount(
1461 ProfileCount(Samples->getHeadSamples() + 1, Function::PCT_Real),
1462 &InlinedGUIDs);
1463
1464 // Compute dominance and loop info needed for propagation.
1465 computeDominanceAndLoopInfo(F);
1466
1467 // Find equivalence classes.
1468 findEquivalenceClasses(F);
1469
1470 // Propagate weights to all edges.
1471 propagateWeights(F);
1472 }
1473
1474 // If coverage checking was requested, compute it now.
1475 if (SampleProfileRecordCoverage) {
1476 unsigned Used = CoverageTracker.countUsedRecords(Samples, PSI);
1477 unsigned Total = CoverageTracker.countBodyRecords(Samples, PSI);
1478 unsigned Coverage = CoverageTracker.computeCoverage(Used, Total);
1479 if (Coverage < SampleProfileRecordCoverage) {
1480 F.getContext().diagnose(DiagnosticInfoSampleProfile(
1481 F.getSubprogram()->getFilename(), getFunctionLoc(F),
1482 Twine(Used) + " of " + Twine(Total) + " available profile records (" +
1483 Twine(Coverage) + "%) were applied",
1484 DS_Warning));
1485 }
1486 }
1487
1488 if (SampleProfileSampleCoverage) {
1489 uint64_t Used = CoverageTracker.getTotalUsedSamples();
1490 uint64_t Total = CoverageTracker.countBodySamples(Samples, PSI);
1491 unsigned Coverage = CoverageTracker.computeCoverage(Used, Total);
1492 if (Coverage < SampleProfileSampleCoverage) {
1493 F.getContext().diagnose(DiagnosticInfoSampleProfile(
1494 F.getSubprogram()->getFilename(), getFunctionLoc(F),
1495 Twine(Used) + " of " + Twine(Total) + " available profile samples (" +
1496 Twine(Coverage) + "%) were applied",
1497 DS_Warning));
1498 }
1499 }
1500 return Changed;
1501}
1502
1503char SampleProfileLoaderLegacyPass::ID = 0;
1504
1505INITIALIZE_PASS_BEGIN(SampleProfileLoaderLegacyPass, "sample-profile",static void *initializeSampleProfileLoaderLegacyPassPassOnce(
PassRegistry &Registry) {
1506 "Sample Profile loader", false, false)static void *initializeSampleProfileLoaderLegacyPassPassOnce(
PassRegistry &Registry) {
1507INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)initializeAssumptionCacheTrackerPass(Registry);
1508INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)initializeTargetTransformInfoWrapperPassPass(Registry);
1509INITIALIZE_PASS_DEPENDENCY(ProfileSummaryInfoWrapperPass)initializeProfileSummaryInfoWrapperPassPass(Registry);
1510INITIALIZE_PASS_END(SampleProfileLoaderLegacyPass, "sample-profile",PassInfo *PI = new PassInfo( "Sample Profile loader", "sample-profile"
, &SampleProfileLoaderLegacyPass::ID, PassInfo::NormalCtor_t
(callDefaultCtor<SampleProfileLoaderLegacyPass>), false
, false); Registry.registerPass(*PI, true); return PI; } static
llvm::once_flag InitializeSampleProfileLoaderLegacyPassPassFlag
; void llvm::initializeSampleProfileLoaderLegacyPassPass(PassRegistry
&Registry) { llvm::call_once(InitializeSampleProfileLoaderLegacyPassPassFlag
, initializeSampleProfileLoaderLegacyPassPassOnce, std::ref(Registry
)); }
1511 "Sample Profile loader", false, false)PassInfo *PI = new PassInfo( "Sample Profile loader", "sample-profile"
, &SampleProfileLoaderLegacyPass::ID, PassInfo::NormalCtor_t
(callDefaultCtor<SampleProfileLoaderLegacyPass>), false
, false); Registry.registerPass(*PI, true); return PI; } static
llvm::once_flag InitializeSampleProfileLoaderLegacyPassPassFlag
; void llvm::initializeSampleProfileLoaderLegacyPassPass(PassRegistry
&Registry) { llvm::call_once(InitializeSampleProfileLoaderLegacyPassPassFlag
, initializeSampleProfileLoaderLegacyPassPassOnce, std::ref(Registry
)); }
1512
1513bool SampleProfileLoader::doInitialization(Module &M) {
1514 auto &Ctx = M.getContext();
1515 auto ReaderOrErr = SampleProfileReader::create(Filename, Ctx);
1516 if (std::error_code EC = ReaderOrErr.getError()) {
1517 std::string Msg = "Could not open profile: " + EC.message();
1518 Ctx.diagnose(DiagnosticInfoSampleProfile(Filename, Msg));
1519 return false;
1520 }
1521 Reader = std::move(ReaderOrErr.get());
1522 ProfileIsValid = (Reader->read() == sampleprof_error::success);
1523 return true;
1524}
1525
1526ModulePass *llvm::createSampleProfileLoaderPass() {
1527 return new SampleProfileLoaderLegacyPass(SampleProfileFile);
1528}
1529
1530ModulePass *llvm::createSampleProfileLoaderPass(StringRef Name) {
1531 return new SampleProfileLoaderLegacyPass(Name);
1532}
1533
1534bool SampleProfileLoader::runOnModule(Module &M, ModuleAnalysisManager *AM,
1535 ProfileSummaryInfo *_PSI) {
1536 if (!ProfileIsValid)
1537 return false;
1538
1539 PSI = _PSI;
1540 if (M.getProfileSummary() == nullptr)
1541 M.setProfileSummary(Reader->getSummary().getMD(M.getContext()));
1542
1543 // Compute the total number of samples collected in this profile.
1544 for (const auto &I : Reader->getProfiles())
1545 TotalCollectedSamples += I.second.getTotalSamples();
1546
1547 // Populate the symbol map.
1548 for (const auto &N_F : M.getValueSymbolTable()) {
1549 StringRef OrigName = N_F.getKey();
1550 Function *F = dyn_cast<Function>(N_F.getValue());
1551 if (F == nullptr)
1552 continue;
1553 SymbolMap[OrigName] = F;
1554 auto pos = OrigName.find('.');
1555 if (pos != StringRef::npos) {
1556 StringRef NewName = OrigName.substr(0, pos);
1557 auto r = SymbolMap.insert(std::make_pair(NewName, F));
1558 // Failiing to insert means there is already an entry in SymbolMap,
1559 // thus there are multiple functions that are mapped to the same
1560 // stripped name. In this case of name conflicting, set the value
1561 // to nullptr to avoid confusion.
1562 if (!r.second)
1563 r.first->second = nullptr;
1564 }
1565 }
1566
1567 bool retval = false;
1568 for (auto &F : M)
1569 if (!F.isDeclaration()) {
1570 clearFunctionData();
1571 retval |= runOnFunction(F, AM);
1572 }
1573 return retval;
1574}
1575
1576bool SampleProfileLoaderLegacyPass::runOnModule(Module &M) {
1577 ACT = &getAnalysis<AssumptionCacheTracker>();
1578 TTIWP = &getAnalysis<TargetTransformInfoWrapperPass>();
1579 ProfileSummaryInfo *PSI =
1580 getAnalysis<ProfileSummaryInfoWrapperPass>().getPSI();
1581 return SampleLoader.runOnModule(M, nullptr, PSI);
1582}
1583
1584bool SampleProfileLoader::runOnFunction(Function &F, ModuleAnalysisManager *AM) {
1585 // Initialize the entry count to -1, which will be treated conservatively
1586 // by getEntryCount as the same as unknown (None). If we have samples this
1587 // will be overwritten in emitAnnotations.
1588 F.setEntryCount(ProfileCount(-1, Function::PCT_Real));
1589 std::unique_ptr<OptimizationRemarkEmitter> OwnedORE;
1590 if (AM) {
1591 auto &FAM =
1592 AM->getResult<FunctionAnalysisManagerModuleProxy>(*F.getParent())
1593 .getManager();
1594 ORE = &FAM.getResult<OptimizationRemarkEmitterAnalysis>(F);
1595 } else {
1596 OwnedORE = make_unique<OptimizationRemarkEmitter>(&F);
1597 ORE = OwnedORE.get();
1598 }
1599 Samples = Reader->getSamplesFor(F);
1600 if (Samples && !Samples->empty())
1601 return emitAnnotations(F);
1602 return false;
1603}
1604
1605PreservedAnalyses SampleProfileLoaderPass::run(Module &M,
1606 ModuleAnalysisManager &AM) {
1607 FunctionAnalysisManager &FAM =
1608 AM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
1609
1610 auto GetAssumptionCache = [&](Function &F) -> AssumptionCache & {
1611 return FAM.getResult<AssumptionAnalysis>(F);
1612 };
1613 auto GetTTI = [&](Function &F) -> TargetTransformInfo & {
1614 return FAM.getResult<TargetIRAnalysis>(F);
1615 };
1616
1617 SampleProfileLoader SampleLoader(
1618 ProfileFileName.empty() ? SampleProfileFile : ProfileFileName,
1619 IsThinLTOPreLink, GetAssumptionCache, GetTTI);
1620
1621 SampleLoader.doInitialization(M);
1622
1623 ProfileSummaryInfo *PSI = &AM.getResult<ProfileSummaryAnalysis>(M);
1624 if (!SampleLoader.runOnModule(M, &AM, PSI))
1625 return PreservedAnalyses::all();
1626
1627 return PreservedAnalyses::none();
1628}