Bug Summary

File:lib/Transforms/IPO/SampleProfile.cpp
Warning:line 721, column 10
Called C++ object pointer is null

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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-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-8/lib/clang/8.0.0 -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-8~svn345461/build-llvm/lib/Transforms/IPO -I /build/llvm-toolchain-snapshot-8~svn345461/lib/Transforms/IPO -I /build/llvm-toolchain-snapshot-8~svn345461/build-llvm/include -I /build/llvm-toolchain-snapshot-8~svn345461/include -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/x86_64-linux-gnu/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/x86_64-linux-gnu/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0/backward -internal-isystem /usr/include/clang/8.0.0/include/ -internal-isystem /usr/local/include -internal-isystem /usr/lib/llvm-8/lib/clang/8.0.0/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-comment -std=c++11 -fdeprecated-macro -fdebug-compilation-dir /build/llvm-toolchain-snapshot-8~svn345461/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-2018-10-27-211344-32123-1 -x c++ /build/llvm-toolchain-snapshot-8~svn345461/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
99// The named file contains a set of transformations that may have been applied
100// to the symbol names between the program from which the sample data was
101// collected and the current program's symbols.
102static cl::opt<std::string> SampleProfileRemappingFile(
103 "sample-profile-remapping-file", cl::init(""), cl::value_desc("filename"),
104 cl::desc("Profile remapping file loaded by -sample-profile"), cl::Hidden);
105
106static cl::opt<unsigned> SampleProfileMaxPropagateIterations(
107 "sample-profile-max-propagate-iterations", cl::init(100),
108 cl::desc("Maximum number of iterations to go through when propagating "
109 "sample block/edge weights through the CFG."));
110
111static cl::opt<unsigned> SampleProfileRecordCoverage(
112 "sample-profile-check-record-coverage", cl::init(0), cl::value_desc("N"),
113 cl::desc("Emit a warning if less than N% of records in the input profile "
114 "are matched to the IR."));
115
116static cl::opt<unsigned> SampleProfileSampleCoverage(
117 "sample-profile-check-sample-coverage", cl::init(0), cl::value_desc("N"),
118 cl::desc("Emit a warning if less than N% of samples in the input profile "
119 "are matched to the IR."));
120
121static cl::opt<bool> NoWarnSampleUnused(
122 "no-warn-sample-unused", cl::init(false), cl::Hidden,
123 cl::desc("Use this option to turn off/on warnings about function with "
124 "samples but without debug information to use those samples. "));
125
126namespace {
127
128using BlockWeightMap = DenseMap<const BasicBlock *, uint64_t>;
129using EquivalenceClassMap = DenseMap<const BasicBlock *, const BasicBlock *>;
130using Edge = std::pair<const BasicBlock *, const BasicBlock *>;
131using EdgeWeightMap = DenseMap<Edge, uint64_t>;
132using BlockEdgeMap =
133 DenseMap<const BasicBlock *, SmallVector<const BasicBlock *, 8>>;
134
135class SampleCoverageTracker {
136public:
137 SampleCoverageTracker() = default;
138
139 bool markSamplesUsed(const FunctionSamples *FS, uint32_t LineOffset,
140 uint32_t Discriminator, uint64_t Samples);
141 unsigned computeCoverage(unsigned Used, unsigned Total) const;
142 unsigned countUsedRecords(const FunctionSamples *FS,
143 ProfileSummaryInfo *PSI) const;
144 unsigned countBodyRecords(const FunctionSamples *FS,
145 ProfileSummaryInfo *PSI) const;
146 uint64_t getTotalUsedSamples() const { return TotalUsedSamples; }
147 uint64_t countBodySamples(const FunctionSamples *FS,
148 ProfileSummaryInfo *PSI) const;
149
150 void clear() {
151 SampleCoverage.clear();
152 TotalUsedSamples = 0;
153 }
154
155private:
156 using BodySampleCoverageMap = std::map<LineLocation, unsigned>;
157 using FunctionSamplesCoverageMap =
158 DenseMap<const FunctionSamples *, BodySampleCoverageMap>;
159
160 /// Coverage map for sampling records.
161 ///
162 /// This map keeps a record of sampling records that have been matched to
163 /// an IR instruction. This is used to detect some form of staleness in
164 /// profiles (see flag -sample-profile-check-coverage).
165 ///
166 /// Each entry in the map corresponds to a FunctionSamples instance. This is
167 /// another map that counts how many times the sample record at the
168 /// given location has been used.
169 FunctionSamplesCoverageMap SampleCoverage;
170
171 /// Number of samples used from the profile.
172 ///
173 /// When a sampling record is used for the first time, the samples from
174 /// that record are added to this accumulator. Coverage is later computed
175 /// based on the total number of samples available in this function and
176 /// its callsites.
177 ///
178 /// Note that this accumulator tracks samples used from a single function
179 /// and all the inlined callsites. Strictly, we should have a map of counters
180 /// keyed by FunctionSamples pointers, but these stats are cleared after
181 /// every function, so we just need to keep a single counter.
182 uint64_t TotalUsedSamples = 0;
183};
184
185/// Sample profile pass.
186///
187/// This pass reads profile data from the file specified by
188/// -sample-profile-file and annotates every affected function with the
189/// profile information found in that file.
190class SampleProfileLoader {
191public:
192 SampleProfileLoader(
193 StringRef Name, StringRef RemapName, bool IsThinLTOPreLink,
194 std::function<AssumptionCache &(Function &)> GetAssumptionCache,
195 std::function<TargetTransformInfo &(Function &)> GetTargetTransformInfo)
196 : GetAC(std::move(GetAssumptionCache)),
197 GetTTI(std::move(GetTargetTransformInfo)), Filename(Name),
198 RemappingFilename(RemapName), IsThinLTOPreLink(IsThinLTOPreLink) {}
199
200 bool doInitialization(Module &M);
201 bool runOnModule(Module &M, ModuleAnalysisManager *AM,
202 ProfileSummaryInfo *_PSI);
203
204 void dump() { Reader->dump(); }
205
206protected:
207 bool runOnFunction(Function &F, ModuleAnalysisManager *AM);
208 unsigned getFunctionLoc(Function &F);
209 bool emitAnnotations(Function &F);
210 ErrorOr<uint64_t> getInstWeight(const Instruction &I);
211 ErrorOr<uint64_t> getBlockWeight(const BasicBlock *BB);
212 const FunctionSamples *findCalleeFunctionSamples(const Instruction &I) const;
213 std::vector<const FunctionSamples *>
214 findIndirectCallFunctionSamples(const Instruction &I, uint64_t &Sum) const;
215 const FunctionSamples *findFunctionSamples(const Instruction &I) const;
216 bool inlineCallInstruction(Instruction *I);
217 bool inlineHotFunctions(Function &F,
218 DenseSet<GlobalValue::GUID> &InlinedGUIDs);
219 void printEdgeWeight(raw_ostream &OS, Edge E);
220 void printBlockWeight(raw_ostream &OS, const BasicBlock *BB) const;
221 void printBlockEquivalence(raw_ostream &OS, const BasicBlock *BB);
222 bool computeBlockWeights(Function &F);
223 void findEquivalenceClasses(Function &F);
224 template <bool IsPostDom>
225 void findEquivalencesFor(BasicBlock *BB1, ArrayRef<BasicBlock *> Descendants,
226 DominatorTreeBase<BasicBlock, IsPostDom> *DomTree);
227
228 void propagateWeights(Function &F);
229 uint64_t visitEdge(Edge E, unsigned *NumUnknownEdges, Edge *UnknownEdge);
230 void buildEdges(Function &F);
231 bool propagateThroughEdges(Function &F, bool UpdateBlockCount);
232 void computeDominanceAndLoopInfo(Function &F);
233 void clearFunctionData();
234
235 /// Map basic blocks to their computed weights.
236 ///
237 /// The weight of a basic block is defined to be the maximum
238 /// of all the instruction weights in that block.
239 BlockWeightMap BlockWeights;
240
241 /// Map edges to their computed weights.
242 ///
243 /// Edge weights are computed by propagating basic block weights in
244 /// SampleProfile::propagateWeights.
245 EdgeWeightMap EdgeWeights;
246
247 /// Set of visited blocks during propagation.
248 SmallPtrSet<const BasicBlock *, 32> VisitedBlocks;
249
250 /// Set of visited edges during propagation.
251 SmallSet<Edge, 32> VisitedEdges;
252
253 /// Equivalence classes for block weights.
254 ///
255 /// Two blocks BB1 and BB2 are in the same equivalence class if they
256 /// dominate and post-dominate each other, and they are in the same loop
257 /// nest. When this happens, the two blocks are guaranteed to execute
258 /// the same number of times.
259 EquivalenceClassMap EquivalenceClass;
260
261 /// Map from function name to Function *. Used to find the function from
262 /// the function name. If the function name contains suffix, additional
263 /// entry is added to map from the stripped name to the function if there
264 /// is one-to-one mapping.
265 StringMap<Function *> SymbolMap;
266
267 /// Dominance, post-dominance and loop information.
268 std::unique_ptr<DominatorTree> DT;
269 std::unique_ptr<PostDominatorTree> PDT;
270 std::unique_ptr<LoopInfo> LI;
271
272 std::function<AssumptionCache &(Function &)> GetAC;
273 std::function<TargetTransformInfo &(Function &)> GetTTI;
274
275 /// Predecessors for each basic block in the CFG.
276 BlockEdgeMap Predecessors;
277
278 /// Successors for each basic block in the CFG.
279 BlockEdgeMap Successors;
280
281 SampleCoverageTracker CoverageTracker;
282
283 /// Profile reader object.
284 std::unique_ptr<SampleProfileReader> Reader;
285
286 /// Samples collected for the body of this function.
287 FunctionSamples *Samples = nullptr;
288
289 /// Name of the profile file to load.
290 std::string Filename;
291
292 /// Name of the profile remapping file to load.
293 std::string RemappingFilename;
294
295 /// Flag indicating whether the profile input loaded successfully.
296 bool ProfileIsValid = false;
297
298 /// Flag indicating if the pass is invoked in ThinLTO compile phase.
299 ///
300 /// In this phase, in annotation, we should not promote indirect calls.
301 /// Instead, we will mark GUIDs that needs to be annotated to the function.
302 bool IsThinLTOPreLink;
303
304 /// Profile Summary Info computed from sample profile.
305 ProfileSummaryInfo *PSI = nullptr;
306
307 /// Total number of samples collected in this profile.
308 ///
309 /// This is the sum of all the samples collected in all the functions executed
310 /// at runtime.
311 uint64_t TotalCollectedSamples = 0;
312
313 /// Optimization Remark Emitter used to emit diagnostic remarks.
314 OptimizationRemarkEmitter *ORE = nullptr;
315};
316
317class SampleProfileLoaderLegacyPass : public ModulePass {
318public:
319 // Class identification, replacement for typeinfo
320 static char ID;
321
322 SampleProfileLoaderLegacyPass(StringRef Name = SampleProfileFile,
323 bool IsThinLTOPreLink = false)
324 : ModulePass(ID),
325 SampleLoader(Name, SampleProfileRemappingFile, IsThinLTOPreLink,
326 [&](Function &F) -> AssumptionCache & {
327 return ACT->getAssumptionCache(F);
328 },
329 [&](Function &F) -> TargetTransformInfo & {
330 return TTIWP->getTTI(F);
331 }) {
332 initializeSampleProfileLoaderLegacyPassPass(
333 *PassRegistry::getPassRegistry());
334 }
335
336 void dump() { SampleLoader.dump(); }
337
338 bool doInitialization(Module &M) override {
339 return SampleLoader.doInitialization(M);
340 }
341
342 StringRef getPassName() const override { return "Sample profile pass"; }
343 bool runOnModule(Module &M) override;
344
345 void getAnalysisUsage(AnalysisUsage &AU) const override {
346 AU.addRequired<AssumptionCacheTracker>();
347 AU.addRequired<TargetTransformInfoWrapperPass>();
348 AU.addRequired<ProfileSummaryInfoWrapperPass>();
349 }
350
351private:
352 SampleProfileLoader SampleLoader;
353 AssumptionCacheTracker *ACT = nullptr;
354 TargetTransformInfoWrapperPass *TTIWP = nullptr;
355};
356
357} // end anonymous namespace
358
359/// Return true if the given callsite is hot wrt to hot cutoff threshold.
360///
361/// Functions that were inlined in the original binary will be represented
362/// in the inline stack in the sample profile. If the profile shows that
363/// the original inline decision was "good" (i.e., the callsite is executed
364/// frequently), then we will recreate the inline decision and apply the
365/// profile from the inlined callsite.
366///
367/// To decide whether an inlined callsite is hot, we compare the callsite
368/// sample count with the hot cutoff computed by ProfileSummaryInfo, it is
369/// regarded as hot if the count is above the cutoff value.
370static bool callsiteIsHot(const FunctionSamples *CallsiteFS,
371 ProfileSummaryInfo *PSI) {
372 if (!CallsiteFS)
373 return false; // The callsite was not inlined in the original binary.
374
375 assert(PSI && "PSI is expected to be non null")((PSI && "PSI is expected to be non null") ? static_cast
<void> (0) : __assert_fail ("PSI && \"PSI is expected to be non null\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Transforms/IPO/SampleProfile.cpp"
, 375, __PRETTY_FUNCTION__))
;
376 uint64_t CallsiteTotalSamples = CallsiteFS->getTotalSamples();
377 return PSI->isHotCount(CallsiteTotalSamples);
378}
379
380/// Mark as used the sample record for the given function samples at
381/// (LineOffset, Discriminator).
382///
383/// \returns true if this is the first time we mark the given record.
384bool SampleCoverageTracker::markSamplesUsed(const FunctionSamples *FS,
385 uint32_t LineOffset,
386 uint32_t Discriminator,
387 uint64_t Samples) {
388 LineLocation Loc(LineOffset, Discriminator);
389 unsigned &Count = SampleCoverage[FS][Loc];
390 bool FirstTime = (++Count == 1);
391 if (FirstTime)
392 TotalUsedSamples += Samples;
393 return FirstTime;
394}
395
396/// Return the number of sample records that were applied from this profile.
397///
398/// This count does not include records from cold inlined callsites.
399unsigned
400SampleCoverageTracker::countUsedRecords(const FunctionSamples *FS,
401 ProfileSummaryInfo *PSI) const {
402 auto I = SampleCoverage.find(FS);
403
404 // The size of the coverage map for FS represents the number of records
405 // that were marked used at least once.
406 unsigned Count = (I != SampleCoverage.end()) ? I->second.size() : 0;
407
408 // If there are inlined callsites in this function, count the samples found
409 // in the respective bodies. However, do not bother counting callees with 0
410 // total samples, these are callees that were never invoked at runtime.
411 for (const auto &I : FS->getCallsiteSamples())
412 for (const auto &J : I.second) {
413 const FunctionSamples *CalleeSamples = &J.second;
414 if (callsiteIsHot(CalleeSamples, PSI))
415 Count += countUsedRecords(CalleeSamples, PSI);
416 }
417
418 return Count;
419}
420
421/// Return the number of sample records in the body of this profile.
422///
423/// This count does not include records from cold inlined callsites.
424unsigned
425SampleCoverageTracker::countBodyRecords(const FunctionSamples *FS,
426 ProfileSummaryInfo *PSI) const {
427 unsigned Count = FS->getBodySamples().size();
428
429 // Only count records in hot callsites.
430 for (const auto &I : FS->getCallsiteSamples())
431 for (const auto &J : I.second) {
432 const FunctionSamples *CalleeSamples = &J.second;
433 if (callsiteIsHot(CalleeSamples, PSI))
434 Count += countBodyRecords(CalleeSamples, PSI);
435 }
436
437 return Count;
438}
439
440/// Return the number of samples collected in the body of this profile.
441///
442/// This count does not include samples from cold inlined callsites.
443uint64_t
444SampleCoverageTracker::countBodySamples(const FunctionSamples *FS,
445 ProfileSummaryInfo *PSI) const {
446 uint64_t Total = 0;
447 for (const auto &I : FS->getBodySamples())
448 Total += I.second.getSamples();
449
450 // Only count samples in hot callsites.
451 for (const auto &I : FS->getCallsiteSamples())
452 for (const auto &J : I.second) {
453 const FunctionSamples *CalleeSamples = &J.second;
454 if (callsiteIsHot(CalleeSamples, PSI))
455 Total += countBodySamples(CalleeSamples, PSI);
456 }
457
458 return Total;
459}
460
461/// Return the fraction of sample records used in this profile.
462///
463/// The returned value is an unsigned integer in the range 0-100 indicating
464/// the percentage of sample records that were used while applying this
465/// profile to the associated function.
466unsigned SampleCoverageTracker::computeCoverage(unsigned Used,
467 unsigned Total) const {
468 assert(Used <= Total &&((Used <= Total && "number of used records cannot exceed the total number of records"
) ? static_cast<void> (0) : __assert_fail ("Used <= Total && \"number of used records cannot exceed the total number of records\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Transforms/IPO/SampleProfile.cpp"
, 469, __PRETTY_FUNCTION__))
469 "number of used records cannot exceed the total number of records")((Used <= Total && "number of used records cannot exceed the total number of records"
) ? static_cast<void> (0) : __assert_fail ("Used <= Total && \"number of used records cannot exceed the total number of records\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Transforms/IPO/SampleProfile.cpp"
, 469, __PRETTY_FUNCTION__))
;
470 return Total > 0 ? Used * 100 / Total : 100;
471}
472
473/// Clear all the per-function data used to load samples and propagate weights.
474void SampleProfileLoader::clearFunctionData() {
475 BlockWeights.clear();
476 EdgeWeights.clear();
477 VisitedBlocks.clear();
478 VisitedEdges.clear();
479 EquivalenceClass.clear();
480 DT = nullptr;
481 PDT = nullptr;
482 LI = nullptr;
483 Predecessors.clear();
484 Successors.clear();
485 CoverageTracker.clear();
486}
487
488#ifndef NDEBUG
489/// Print the weight of edge \p E on stream \p OS.
490///
491/// \param OS Stream to emit the output to.
492/// \param E Edge to print.
493void SampleProfileLoader::printEdgeWeight(raw_ostream &OS, Edge E) {
494 OS << "weight[" << E.first->getName() << "->" << E.second->getName()
495 << "]: " << EdgeWeights[E] << "\n";
496}
497
498/// Print the equivalence class 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::printBlockEquivalence(raw_ostream &OS,
503 const BasicBlock *BB) {
504 const BasicBlock *Equiv = EquivalenceClass[BB];
505 OS << "equivalence[" << BB->getName()
506 << "]: " << ((Equiv) ? EquivalenceClass[BB]->getName() : "NONE") << "\n";
507}
508
509/// Print the weight of block \p BB on stream \p OS.
510///
511/// \param OS Stream to emit the output to.
512/// \param BB Block to print.
513void SampleProfileLoader::printBlockWeight(raw_ostream &OS,
514 const BasicBlock *BB) const {
515 const auto &I = BlockWeights.find(BB);
516 uint64_t W = (I == BlockWeights.end() ? 0 : I->second);
517 OS << "weight[" << BB->getName() << "]: " << W << "\n";
518}
519#endif
520
521/// Get the weight for an instruction.
522///
523/// The "weight" of an instruction \p Inst is the number of samples
524/// collected on that instruction at runtime. To retrieve it, we
525/// need to compute the line number of \p Inst relative to the start of its
526/// function. We use HeaderLineno to compute the offset. We then
527/// look up the samples collected for \p Inst using BodySamples.
528///
529/// \param Inst Instruction to query.
530///
531/// \returns the weight of \p Inst.
532ErrorOr<uint64_t> SampleProfileLoader::getInstWeight(const Instruction &Inst) {
533 const DebugLoc &DLoc = Inst.getDebugLoc();
534 if (!DLoc)
2
Assuming the condition is false
3
Taking false branch
9
Assuming the condition is false
10
Taking false branch
535 return std::error_code();
536
537 const FunctionSamples *FS = findFunctionSamples(Inst);
11
Calling 'SampleProfileLoader::findFunctionSamples'
538 if (!FS)
4
Assuming 'FS' is null
5
Taking true branch
539 return std::error_code();
540
541 // Ignore all intrinsics and branch instructions.
542 // Branch instruction usually contains debug info from sources outside of
543 // the residing basic block, thus we ignore them during annotation.
544 if (isa<BranchInst>(Inst) || isa<IntrinsicInst>(Inst))
545 return std::error_code();
546
547 // If a direct call/invoke instruction is inlined in profile
548 // (findCalleeFunctionSamples returns non-empty result), but not inlined here,
549 // it means that the inlined callsite has no sample, thus the call
550 // instruction should have 0 count.
551 if ((isa<CallInst>(Inst) || isa<InvokeInst>(Inst)) &&
552 !ImmutableCallSite(&Inst).isIndirectCall() &&
553 findCalleeFunctionSamples(Inst))
554 return 0;
555
556 const DILocation *DIL = DLoc;
557 uint32_t LineOffset = FunctionSamples::getOffset(DIL);
558 uint32_t Discriminator = DIL->getBaseDiscriminator();
559 ErrorOr<uint64_t> R = FS->findSamplesAt(LineOffset, Discriminator);
560 if (R) {
561 bool FirstMark =
562 CoverageTracker.markSamplesUsed(FS, LineOffset, Discriminator, R.get());
563 if (FirstMark) {
564 ORE->emit([&]() {
565 OptimizationRemarkAnalysis Remark(DEBUG_TYPE"sample-profile", "AppliedSamples", &Inst);
566 Remark << "Applied " << ore::NV("NumSamples", *R);
567 Remark << " samples from profile (offset: ";
568 Remark << ore::NV("LineOffset", LineOffset);
569 if (Discriminator) {
570 Remark << ".";
571 Remark << ore::NV("Discriminator", Discriminator);
572 }
573 Remark << ")";
574 return Remark;
575 });
576 }
577 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
)
578 << 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
)
579 << " (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
)
580 << 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
)
581 << ")\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
)
;
582 }
583 return R;
584}
585
586/// Compute the weight of a basic block.
587///
588/// The weight of basic block \p BB is the maximum weight of all the
589/// instructions in BB.
590///
591/// \param BB The basic block to query.
592///
593/// \returns the weight for \p BB.
594ErrorOr<uint64_t> SampleProfileLoader::getBlockWeight(const BasicBlock *BB) {
595 uint64_t Max = 0;
596 bool HasWeight = false;
597 for (auto &I : BB->getInstList()) {
598 const ErrorOr<uint64_t> &R = getInstWeight(I);
1
Calling 'SampleProfileLoader::getInstWeight'
6
Returning from 'SampleProfileLoader::getInstWeight'
8
Calling 'SampleProfileLoader::getInstWeight'
599 if (R) {
7
Taking false branch
600 Max = std::max(Max, R.get());
601 HasWeight = true;
602 }
603 }
604 return HasWeight ? ErrorOr<uint64_t>(Max) : std::error_code();
605}
606
607/// Compute and store the weights of every basic block.
608///
609/// This populates the BlockWeights map by computing
610/// the weights of every basic block in the CFG.
611///
612/// \param F The function to query.
613bool SampleProfileLoader::computeBlockWeights(Function &F) {
614 bool Changed = false;
615 LLVM_DEBUG(dbgs() << "Block weights\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { dbgs() << "Block weights\n"; } } while
(false)
;
616 for (const auto &BB : F) {
617 ErrorOr<uint64_t> Weight = getBlockWeight(&BB);
618 if (Weight) {
619 BlockWeights[&BB] = Weight.get();
620 VisitedBlocks.insert(&BB);
621 Changed = true;
622 }
623 LLVM_DEBUG(printBlockWeight(dbgs(), &BB))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { printBlockWeight(dbgs(), &BB); } } while
(false)
;
624 }
625
626 return Changed;
627}
628
629/// Get the FunctionSamples for a call instruction.
630///
631/// The FunctionSamples of a call/invoke instruction \p Inst is the inlined
632/// instance in which that call instruction is calling to. It contains
633/// all samples that resides in the inlined instance. We first find the
634/// inlined instance in which the call instruction is from, then we
635/// traverse its children to find the callsite with the matching
636/// location.
637///
638/// \param Inst Call/Invoke instruction to query.
639///
640/// \returns The FunctionSamples pointer to the inlined instance.
641const FunctionSamples *
642SampleProfileLoader::findCalleeFunctionSamples(const Instruction &Inst) const {
643 const DILocation *DIL = Inst.getDebugLoc();
644 if (!DIL) {
645 return nullptr;
646 }
647
648 StringRef CalleeName;
649 if (const CallInst *CI = dyn_cast<CallInst>(&Inst))
650 if (Function *Callee = CI->getCalledFunction())
651 CalleeName = Callee->getName();
652
653 const FunctionSamples *FS = findFunctionSamples(Inst);
654 if (FS == nullptr)
655 return nullptr;
656
657 return FS->findFunctionSamplesAt(LineLocation(FunctionSamples::getOffset(DIL),
658 DIL->getBaseDiscriminator()),
659 CalleeName);
660}
661
662/// Returns a vector of FunctionSamples that are the indirect call targets
663/// of \p Inst. The vector is sorted by the total number of samples. Stores
664/// the total call count of the indirect call in \p Sum.
665std::vector<const FunctionSamples *>
666SampleProfileLoader::findIndirectCallFunctionSamples(
667 const Instruction &Inst, uint64_t &Sum) const {
668 const DILocation *DIL = Inst.getDebugLoc();
669 std::vector<const FunctionSamples *> R;
670
671 if (!DIL) {
672 return R;
673 }
674
675 const FunctionSamples *FS = findFunctionSamples(Inst);
676 if (FS == nullptr)
677 return R;
678
679 uint32_t LineOffset = FunctionSamples::getOffset(DIL);
680 uint32_t Discriminator = DIL->getBaseDiscriminator();
681
682 auto T = FS->findCallTargetMapAt(LineOffset, Discriminator);
683 Sum = 0;
684 if (T)
685 for (const auto &T_C : T.get())
686 Sum += T_C.second;
687 if (const FunctionSamplesMap *M = FS->findFunctionSamplesMapAt(LineLocation(
688 FunctionSamples::getOffset(DIL), DIL->getBaseDiscriminator()))) {
689 if (M->empty())
690 return R;
691 for (const auto &NameFS : *M) {
692 Sum += NameFS.second.getEntrySamples();
693 R.push_back(&NameFS.second);
694 }
695 llvm::sort(R, [](const FunctionSamples *L, const FunctionSamples *R) {
696 if (L->getEntrySamples() != R->getEntrySamples())
697 return L->getEntrySamples() > R->getEntrySamples();
698 return FunctionSamples::getGUID(L->getName()) <
699 FunctionSamples::getGUID(R->getName());
700 });
701 }
702 return R;
703}
704
705/// Get the FunctionSamples for an instruction.
706///
707/// The FunctionSamples of an instruction \p Inst is the inlined instance
708/// in which that instruction is coming from. We traverse the inline stack
709/// of that instruction, and match it with the tree nodes in the profile.
710///
711/// \param Inst Instruction to query.
712///
713/// \returns the FunctionSamples pointer to the inlined instance.
714const FunctionSamples *
715SampleProfileLoader::findFunctionSamples(const Instruction &Inst) const {
716 SmallVector<std::pair<LineLocation, StringRef>, 10> S;
717 const DILocation *DIL = Inst.getDebugLoc();
718 if (!DIL)
12
Assuming 'DIL' is non-null
13
Taking false branch
719 return Samples;
720
721 return Samples->findFunctionSamples(DIL);
14
Called C++ object pointer is null
722}
723
724bool SampleProfileLoader::inlineCallInstruction(Instruction *I) {
725 assert(isa<CallInst>(I) || isa<InvokeInst>(I))((isa<CallInst>(I) || isa<InvokeInst>(I)) ? static_cast
<void> (0) : __assert_fail ("isa<CallInst>(I) || isa<InvokeInst>(I)"
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Transforms/IPO/SampleProfile.cpp"
, 725, __PRETTY_FUNCTION__))
;
726 CallSite CS(I);
727 Function *CalledFunction = CS.getCalledFunction();
728 assert(CalledFunction)((CalledFunction) ? static_cast<void> (0) : __assert_fail
("CalledFunction", "/build/llvm-toolchain-snapshot-8~svn345461/lib/Transforms/IPO/SampleProfile.cpp"
, 728, __PRETTY_FUNCTION__))
;
729 DebugLoc DLoc = I->getDebugLoc();
730 BasicBlock *BB = I->getParent();
731 InlineParams Params = getInlineParams();
732 Params.ComputeFullInlineCost = true;
733 // Checks if there is anything in the reachable portion of the callee at
734 // this callsite that makes this inlining potentially illegal. Need to
735 // set ComputeFullInlineCost, otherwise getInlineCost may return early
736 // when cost exceeds threshold without checking all IRs in the callee.
737 // The acutal cost does not matter because we only checks isNever() to
738 // see if it is legal to inline the callsite.
739 InlineCost Cost = getInlineCost(CS, Params, GetTTI(*CalledFunction), GetAC,
740 None, nullptr, nullptr);
741 if (Cost.isNever()) {
742 ORE->emit(OptimizationRemark(DEBUG_TYPE"sample-profile", "Not inline", DLoc, BB)
743 << "incompatible inlining");
744 return false;
745 }
746 InlineFunctionInfo IFI(nullptr, &GetAC);
747 if (InlineFunction(CS, IFI)) {
748 // The call to InlineFunction erases I, so we can't pass it here.
749 ORE->emit(OptimizationRemark(DEBUG_TYPE"sample-profile", "HotInline", DLoc, BB)
750 << "inlined hot callee '" << ore::NV("Callee", CalledFunction)
751 << "' into '" << ore::NV("Caller", BB->getParent()) << "'");
752 return true;
753 }
754 return false;
755}
756
757/// Iteratively inline hot callsites of a function.
758///
759/// Iteratively traverse all callsites of the function \p F, and find if
760/// the corresponding inlined instance exists and is hot in profile. If
761/// it is hot enough, inline the callsites and adds new callsites of the
762/// callee into the caller. If the call is an indirect call, first promote
763/// it to direct call. Each indirect call is limited with a single target.
764///
765/// \param F function to perform iterative inlining.
766/// \param InlinedGUIDs a set to be updated to include all GUIDs that are
767/// inlined in the profiled binary.
768///
769/// \returns True if there is any inline happened.
770bool SampleProfileLoader::inlineHotFunctions(
771 Function &F, DenseSet<GlobalValue::GUID> &InlinedGUIDs) {
772 DenseSet<Instruction *> PromotedInsns;
773 bool Changed = false;
774 while (true) {
775 bool LocalChanged = false;
776 SmallVector<Instruction *, 10> CIS;
777 for (auto &BB : F) {
778 bool Hot = false;
779 SmallVector<Instruction *, 10> Candidates;
780 for (auto &I : BB.getInstList()) {
781 const FunctionSamples *FS = nullptr;
782 if ((isa<CallInst>(I) || isa<InvokeInst>(I)) &&
783 !isa<IntrinsicInst>(I) && (FS = findCalleeFunctionSamples(I))) {
784 Candidates.push_back(&I);
785 if (callsiteIsHot(FS, PSI))
786 Hot = true;
787 }
788 }
789 if (Hot) {
790 CIS.insert(CIS.begin(), Candidates.begin(), Candidates.end());
791 }
792 }
793 for (auto I : CIS) {
794 Function *CalledFunction = CallSite(I).getCalledFunction();
795 // Do not inline recursive calls.
796 if (CalledFunction == &F)
797 continue;
798 if (CallSite(I).isIndirectCall()) {
799 if (PromotedInsns.count(I))
800 continue;
801 uint64_t Sum;
802 for (const auto *FS : findIndirectCallFunctionSamples(*I, Sum)) {
803 if (IsThinLTOPreLink) {
804 FS->findInlinedFunctions(InlinedGUIDs, F.getParent(),
805 PSI->getOrCompHotCountThreshold());
806 continue;
807 }
808 auto CalleeFunctionName = FS->getFuncNameInModule(F.getParent());
809 // If it is a recursive call, we do not inline it as it could bloat
810 // the code exponentially. There is way to better handle this, e.g.
811 // clone the caller first, and inline the cloned caller if it is
812 // recursive. As llvm does not inline recursive calls, we will
813 // simply ignore it instead of handling it explicitly.
814 if (CalleeFunctionName == F.getName())
815 continue;
816
817 const char *Reason = "Callee function not available";
818 auto R = SymbolMap.find(CalleeFunctionName);
819 if (R != SymbolMap.end() && R->getValue() &&
820 !R->getValue()->isDeclaration() &&
821 R->getValue()->getSubprogram() &&
822 isLegalToPromote(CallSite(I), R->getValue(), &Reason)) {
823 uint64_t C = FS->getEntrySamples();
824 Instruction *DI =
825 pgo::promoteIndirectCall(I, R->getValue(), C, Sum, false, ORE);
826 Sum -= C;
827 PromotedInsns.insert(I);
828 // If profile mismatches, we should not attempt to inline DI.
829 if ((isa<CallInst>(DI) || isa<InvokeInst>(DI)) &&
830 inlineCallInstruction(DI))
831 LocalChanged = true;
832 } else {
833 LLVM_DEBUG(dbgs()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { dbgs() << "\nFailed to promote indirect call to "
<< CalleeFunctionName << " because " << Reason
<< "\n"; } } while (false)
834 << "\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)
835 << 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)
;
836 }
837 }
838 } else if (CalledFunction && CalledFunction->getSubprogram() &&
839 !CalledFunction->isDeclaration()) {
840 if (inlineCallInstruction(I))
841 LocalChanged = true;
842 } else if (IsThinLTOPreLink) {
843 findCalleeFunctionSamples(*I)->findInlinedFunctions(
844 InlinedGUIDs, F.getParent(), PSI->getOrCompHotCountThreshold());
845 }
846 }
847 if (LocalChanged) {
848 Changed = true;
849 } else {
850 break;
851 }
852 }
853 return Changed;
854}
855
856/// Find equivalence classes for the given block.
857///
858/// This finds all the blocks that are guaranteed to execute the same
859/// number of times as \p BB1. To do this, it traverses all the
860/// descendants of \p BB1 in the dominator or post-dominator tree.
861///
862/// A block BB2 will be in the same equivalence class as \p BB1 if
863/// the following holds:
864///
865/// 1- \p BB1 is a descendant of BB2 in the opposite tree. So, if BB2
866/// is a descendant of \p BB1 in the dominator tree, then BB2 should
867/// dominate BB1 in the post-dominator tree.
868///
869/// 2- Both BB2 and \p BB1 must be in the same loop.
870///
871/// For every block BB2 that meets those two requirements, we set BB2's
872/// equivalence class to \p BB1.
873///
874/// \param BB1 Block to check.
875/// \param Descendants Descendants of \p BB1 in either the dom or pdom tree.
876/// \param DomTree Opposite dominator tree. If \p Descendants is filled
877/// with blocks from \p BB1's dominator tree, then
878/// this is the post-dominator tree, and vice versa.
879template <bool IsPostDom>
880void SampleProfileLoader::findEquivalencesFor(
881 BasicBlock *BB1, ArrayRef<BasicBlock *> Descendants,
882 DominatorTreeBase<BasicBlock, IsPostDom> *DomTree) {
883 const BasicBlock *EC = EquivalenceClass[BB1];
884 uint64_t Weight = BlockWeights[EC];
885 for (const auto *BB2 : Descendants) {
886 bool IsDomParent = DomTree->dominates(BB2, BB1);
887 bool IsInSameLoop = LI->getLoopFor(BB1) == LI->getLoopFor(BB2);
888 if (BB1 != BB2 && IsDomParent && IsInSameLoop) {
889 EquivalenceClass[BB2] = EC;
890 // If BB2 is visited, then the entire EC should be marked as visited.
891 if (VisitedBlocks.count(BB2)) {
892 VisitedBlocks.insert(EC);
893 }
894
895 // If BB2 is heavier than BB1, make BB2 have the same weight
896 // as BB1.
897 //
898 // Note that we don't worry about the opposite situation here
899 // (when BB2 is lighter than BB1). We will deal with this
900 // during the propagation phase. Right now, we just want to
901 // make sure that BB1 has the largest weight of all the
902 // members of its equivalence set.
903 Weight = std::max(Weight, BlockWeights[BB2]);
904 }
905 }
906 if (EC == &EC->getParent()->getEntryBlock()) {
907 BlockWeights[EC] = Samples->getHeadSamples() + 1;
908 } else {
909 BlockWeights[EC] = Weight;
910 }
911}
912
913/// Find equivalence classes.
914///
915/// Since samples may be missing from blocks, we can fill in the gaps by setting
916/// the weights of all the blocks in the same equivalence class to the same
917/// weight. To compute the concept of equivalence, we use dominance and loop
918/// information. Two blocks B1 and B2 are in the same equivalence class if B1
919/// dominates B2, B2 post-dominates B1 and both are in the same loop.
920///
921/// \param F The function to query.
922void SampleProfileLoader::findEquivalenceClasses(Function &F) {
923 SmallVector<BasicBlock *, 8> DominatedBBs;
924 LLVM_DEBUG(dbgs() << "\nBlock equivalence classes\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { dbgs() << "\nBlock equivalence classes\n"
; } } while (false)
;
925 // Find equivalence sets based on dominance and post-dominance information.
926 for (auto &BB : F) {
927 BasicBlock *BB1 = &BB;
928
929 // Compute BB1's equivalence class once.
930 if (EquivalenceClass.count(BB1)) {
931 LLVM_DEBUG(printBlockEquivalence(dbgs(), BB1))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { printBlockEquivalence(dbgs(), BB1); } }
while (false)
;
932 continue;
933 }
934
935 // By default, blocks are in their own equivalence class.
936 EquivalenceClass[BB1] = BB1;
937
938 // Traverse all the blocks dominated by BB1. We are looking for
939 // every basic block BB2 such that:
940 //
941 // 1- BB1 dominates BB2.
942 // 2- BB2 post-dominates BB1.
943 // 3- BB1 and BB2 are in the same loop nest.
944 //
945 // If all those conditions hold, it means that BB2 is executed
946 // as many times as BB1, so they are placed in the same equivalence
947 // class by making BB2's equivalence class be BB1.
948 DominatedBBs.clear();
949 DT->getDescendants(BB1, DominatedBBs);
950 findEquivalencesFor(BB1, DominatedBBs, PDT.get());
951
952 LLVM_DEBUG(printBlockEquivalence(dbgs(), BB1))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { printBlockEquivalence(dbgs(), BB1); } }
while (false)
;
953 }
954
955 // Assign weights to equivalence classes.
956 //
957 // All the basic blocks in the same equivalence class will execute
958 // the same number of times. Since we know that the head block in
959 // each equivalence class has the largest weight, assign that weight
960 // to all the blocks in that equivalence class.
961 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)
962 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)
;
963 for (auto &BI : F) {
964 const BasicBlock *BB = &BI;
965 const BasicBlock *EquivBB = EquivalenceClass[BB];
966 if (BB != EquivBB)
967 BlockWeights[BB] = BlockWeights[EquivBB];
968 LLVM_DEBUG(printBlockWeight(dbgs(), BB))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { printBlockWeight(dbgs(), BB); } } while
(false)
;
969 }
970}
971
972/// Visit the given edge to decide if it has a valid weight.
973///
974/// If \p E has not been visited before, we copy to \p UnknownEdge
975/// and increment the count of unknown edges.
976///
977/// \param E Edge to visit.
978/// \param NumUnknownEdges Current number of unknown edges.
979/// \param UnknownEdge Set if E has not been visited before.
980///
981/// \returns E's weight, if known. Otherwise, return 0.
982uint64_t SampleProfileLoader::visitEdge(Edge E, unsigned *NumUnknownEdges,
983 Edge *UnknownEdge) {
984 if (!VisitedEdges.count(E)) {
985 (*NumUnknownEdges)++;
986 *UnknownEdge = E;
987 return 0;
988 }
989
990 return EdgeWeights[E];
991}
992
993/// Propagate weights through incoming/outgoing edges.
994///
995/// If the weight of a basic block is known, and there is only one edge
996/// with an unknown weight, we can calculate the weight of that edge.
997///
998/// Similarly, if all the edges have a known count, we can calculate the
999/// count of the basic block, if needed.
1000///
1001/// \param F Function to process.
1002/// \param UpdateBlockCount Whether we should update basic block counts that
1003/// has already been annotated.
1004///
1005/// \returns True if new weights were assigned to edges or blocks.
1006bool SampleProfileLoader::propagateThroughEdges(Function &F,
1007 bool UpdateBlockCount) {
1008 bool Changed = false;
1009 LLVM_DEBUG(dbgs() << "\nPropagation through edges\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { dbgs() << "\nPropagation through edges\n"
; } } while (false)
;
1010 for (const auto &BI : F) {
1011 const BasicBlock *BB = &BI;
1012 const BasicBlock *EC = EquivalenceClass[BB];
1013
1014 // Visit all the predecessor and successor edges to determine
1015 // which ones have a weight assigned already. Note that it doesn't
1016 // matter that we only keep track of a single unknown edge. The
1017 // only case we are interested in handling is when only a single
1018 // edge is unknown (see setEdgeOrBlockWeight).
1019 for (unsigned i = 0; i < 2; i++) {
1020 uint64_t TotalWeight = 0;
1021 unsigned NumUnknownEdges = 0, NumTotalEdges = 0;
1022 Edge UnknownEdge, SelfReferentialEdge, SingleEdge;
1023
1024 if (i == 0) {
1025 // First, visit all predecessor edges.
1026 NumTotalEdges = Predecessors[BB].size();
1027 for (auto *Pred : Predecessors[BB]) {
1028 Edge E = std::make_pair(Pred, BB);
1029 TotalWeight += visitEdge(E, &NumUnknownEdges, &UnknownEdge);
1030 if (E.first == E.second)
1031 SelfReferentialEdge = E;
1032 }
1033 if (NumTotalEdges == 1) {
1034 SingleEdge = std::make_pair(Predecessors[BB][0], BB);
1035 }
1036 } else {
1037 // On the second round, visit all successor edges.
1038 NumTotalEdges = Successors[BB].size();
1039 for (auto *Succ : Successors[BB]) {
1040 Edge E = std::make_pair(BB, Succ);
1041 TotalWeight += visitEdge(E, &NumUnknownEdges, &UnknownEdge);
1042 }
1043 if (NumTotalEdges == 1) {
1044 SingleEdge = std::make_pair(BB, Successors[BB][0]);
1045 }
1046 }
1047
1048 // After visiting all the edges, there are three cases that we
1049 // can handle immediately:
1050 //
1051 // - All the edge weights are known (i.e., NumUnknownEdges == 0).
1052 // In this case, we simply check that the sum of all the edges
1053 // is the same as BB's weight. If not, we change BB's weight
1054 // to match. Additionally, if BB had not been visited before,
1055 // we mark it visited.
1056 //
1057 // - Only one edge is unknown and BB has already been visited.
1058 // In this case, we can compute the weight of the edge by
1059 // subtracting the total block weight from all the known
1060 // edge weights. If the edges weight more than BB, then the
1061 // edge of the last remaining edge is set to zero.
1062 //
1063 // - There exists a self-referential edge and the weight of BB is
1064 // known. In this case, this edge can be based on BB's weight.
1065 // We add up all the other known edges and set the weight on
1066 // the self-referential edge as we did in the previous case.
1067 //
1068 // In any other case, we must continue iterating. Eventually,
1069 // all edges will get a weight, or iteration will stop when
1070 // it reaches SampleProfileMaxPropagateIterations.
1071 if (NumUnknownEdges <= 1) {
1072 uint64_t &BBWeight = BlockWeights[EC];
1073 if (NumUnknownEdges == 0) {
1074 if (!VisitedBlocks.count(EC)) {
1075 // If we already know the weight of all edges, the weight of the
1076 // basic block can be computed. It should be no larger than the sum
1077 // of all edge weights.
1078 if (TotalWeight > BBWeight) {
1079 BBWeight = TotalWeight;
1080 Changed = true;
1081 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)
1082 << " 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)
1083 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)
;
1084 }
1085 } else if (NumTotalEdges == 1 &&
1086 EdgeWeights[SingleEdge] < BlockWeights[EC]) {
1087 // If there is only one edge for the visited basic block, use the
1088 // block weight to adjust edge weight if edge weight is smaller.
1089 EdgeWeights[SingleEdge] = BlockWeights[EC];
1090 Changed = true;
1091 }
1092 } else if (NumUnknownEdges == 1 && VisitedBlocks.count(EC)) {
1093 // If there is a single unknown edge and the block has been
1094 // visited, then we can compute E's weight.
1095 if (BBWeight >= TotalWeight)
1096 EdgeWeights[UnknownEdge] = BBWeight - TotalWeight;
1097 else
1098 EdgeWeights[UnknownEdge] = 0;
1099 const BasicBlock *OtherEC;
1100 if (i == 0)
1101 OtherEC = EquivalenceClass[UnknownEdge.first];
1102 else
1103 OtherEC = EquivalenceClass[UnknownEdge.second];
1104 // Edge weights should never exceed the BB weights it connects.
1105 if (VisitedBlocks.count(OtherEC) &&
1106 EdgeWeights[UnknownEdge] > BlockWeights[OtherEC])
1107 EdgeWeights[UnknownEdge] = BlockWeights[OtherEC];
1108 VisitedEdges.insert(UnknownEdge);
1109 Changed = true;
1110 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)
1111 printEdgeWeight(dbgs(), UnknownEdge))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { dbgs() << "Set weight for edge: "
; printEdgeWeight(dbgs(), UnknownEdge); } } while (false)
;
1112 }
1113 } else if (VisitedBlocks.count(EC) && BlockWeights[EC] == 0) {
1114 // If a block Weights 0, all its in/out edges should weight 0.
1115 if (i == 0) {
1116 for (auto *Pred : Predecessors[BB]) {
1117 Edge E = std::make_pair(Pred, BB);
1118 EdgeWeights[E] = 0;
1119 VisitedEdges.insert(E);
1120 }
1121 } else {
1122 for (auto *Succ : Successors[BB]) {
1123 Edge E = std::make_pair(BB, Succ);
1124 EdgeWeights[E] = 0;
1125 VisitedEdges.insert(E);
1126 }
1127 }
1128 } else if (SelfReferentialEdge.first && VisitedBlocks.count(EC)) {
1129 uint64_t &BBWeight = BlockWeights[BB];
1130 // We have a self-referential edge and the weight of BB is known.
1131 if (BBWeight >= TotalWeight)
1132 EdgeWeights[SelfReferentialEdge] = BBWeight - TotalWeight;
1133 else
1134 EdgeWeights[SelfReferentialEdge] = 0;
1135 VisitedEdges.insert(SelfReferentialEdge);
1136 Changed = true;
1137 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
)
1138 printEdgeWeight(dbgs(), SelfReferentialEdge))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { dbgs() << "Set self-referential edge weight to: "
; printEdgeWeight(dbgs(), SelfReferentialEdge); } } while (false
)
;
1139 }
1140 if (UpdateBlockCount && !VisitedBlocks.count(EC) && TotalWeight > 0) {
1141 BlockWeights[EC] = TotalWeight;
1142 VisitedBlocks.insert(EC);
1143 Changed = true;
1144 }
1145 }
1146 }
1147
1148 return Changed;
1149}
1150
1151/// Build in/out edge lists for each basic block in the CFG.
1152///
1153/// We are interested in unique edges. If a block B1 has multiple
1154/// edges to another block B2, we only add a single B1->B2 edge.
1155void SampleProfileLoader::buildEdges(Function &F) {
1156 for (auto &BI : F) {
1157 BasicBlock *B1 = &BI;
1158
1159 // Add predecessors for B1.
1160 SmallPtrSet<BasicBlock *, 16> Visited;
1161 if (!Predecessors[B1].empty())
1162 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-8~svn345461/lib/Transforms/IPO/SampleProfile.cpp"
, 1162)
;
1163 for (pred_iterator PI = pred_begin(B1), PE = pred_end(B1); PI != PE; ++PI) {
1164 BasicBlock *B2 = *PI;
1165 if (Visited.insert(B2).second)
1166 Predecessors[B1].push_back(B2);
1167 }
1168
1169 // Add successors for B1.
1170 Visited.clear();
1171 if (!Successors[B1].empty())
1172 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-8~svn345461/lib/Transforms/IPO/SampleProfile.cpp"
, 1172)
;
1173 for (succ_iterator SI = succ_begin(B1), SE = succ_end(B1); SI != SE; ++SI) {
1174 BasicBlock *B2 = *SI;
1175 if (Visited.insert(B2).second)
1176 Successors[B1].push_back(B2);
1177 }
1178 }
1179}
1180
1181/// Returns the sorted CallTargetMap \p M by count in descending order.
1182static SmallVector<InstrProfValueData, 2> SortCallTargets(
1183 const SampleRecord::CallTargetMap &M) {
1184 SmallVector<InstrProfValueData, 2> R;
1185 for (auto I = M.begin(); I != M.end(); ++I)
1186 R.push_back({FunctionSamples::getGUID(I->getKey()), I->getValue()});
1187 llvm::sort(R, [](const InstrProfValueData &L, const InstrProfValueData &R) {
1188 if (L.Count == R.Count)
1189 return L.Value > R.Value;
1190 else
1191 return L.Count > R.Count;
1192 });
1193 return R;
1194}
1195
1196/// Propagate weights into edges
1197///
1198/// The following rules are applied to every block BB in the CFG:
1199///
1200/// - If BB has a single predecessor/successor, then the weight
1201/// of that edge is the weight of the block.
1202///
1203/// - If all incoming or outgoing edges are known except one, and the
1204/// weight of the block is already known, the weight of the unknown
1205/// edge will be the weight of the block minus the sum of all the known
1206/// edges. If the sum of all the known edges is larger than BB's weight,
1207/// we set the unknown edge weight to zero.
1208///
1209/// - If there is a self-referential edge, and the weight of the block is
1210/// known, the weight for that edge is set to the weight of the block
1211/// minus the weight of the other incoming edges to that block (if
1212/// known).
1213void SampleProfileLoader::propagateWeights(Function &F) {
1214 bool Changed = true;
1215 unsigned I = 0;
1216
1217 // If BB weight is larger than its corresponding loop's header BB weight,
1218 // use the BB weight to replace the loop header BB weight.
1219 for (auto &BI : F) {
1220 BasicBlock *BB = &BI;
1221 Loop *L = LI->getLoopFor(BB);
1222 if (!L) {
1223 continue;
1224 }
1225 BasicBlock *Header = L->getHeader();
1226 if (Header && BlockWeights[BB] > BlockWeights[Header]) {
1227 BlockWeights[Header] = BlockWeights[BB];
1228 }
1229 }
1230
1231 // Before propagation starts, build, for each block, a list of
1232 // unique predecessors and successors. This is necessary to handle
1233 // identical edges in multiway branches. Since we visit all blocks and all
1234 // edges of the CFG, it is cleaner to build these lists once at the start
1235 // of the pass.
1236 buildEdges(F);
1237
1238 // Propagate until we converge or we go past the iteration limit.
1239 while (Changed && I++ < SampleProfileMaxPropagateIterations) {
1240 Changed = propagateThroughEdges(F, false);
1241 }
1242
1243 // The first propagation propagates BB counts from annotated BBs to unknown
1244 // BBs. The 2nd propagation pass resets edges weights, and use all BB weights
1245 // to propagate edge weights.
1246 VisitedEdges.clear();
1247 Changed = true;
1248 while (Changed && I++ < SampleProfileMaxPropagateIterations) {
1249 Changed = propagateThroughEdges(F, false);
1250 }
1251
1252 // The 3rd propagation pass allows adjust annotated BB weights that are
1253 // obviously wrong.
1254 Changed = true;
1255 while (Changed && I++ < SampleProfileMaxPropagateIterations) {
1256 Changed = propagateThroughEdges(F, true);
1257 }
1258
1259 // Generate MD_prof metadata for every branch instruction using the
1260 // edge weights computed during propagation.
1261 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)
;
1262 LLVMContext &Ctx = F.getContext();
1263 MDBuilder MDB(Ctx);
1264 for (auto &BI : F) {
1265 BasicBlock *BB = &BI;
1266
1267 if (BlockWeights[BB]) {
1268 for (auto &I : BB->getInstList()) {
1269 if (!isa<CallInst>(I) && !isa<InvokeInst>(I))
1270 continue;
1271 CallSite CS(&I);
1272 if (!CS.getCalledFunction()) {
1273 const DebugLoc &DLoc = I.getDebugLoc();
1274 if (!DLoc)
1275 continue;
1276 const DILocation *DIL = DLoc;
1277 uint32_t LineOffset = FunctionSamples::getOffset(DIL);
1278 uint32_t Discriminator = DIL->getBaseDiscriminator();
1279
1280 const FunctionSamples *FS = findFunctionSamples(I);
1281 if (!FS)
1282 continue;
1283 auto T = FS->findCallTargetMapAt(LineOffset, Discriminator);
1284 if (!T || T.get().empty())
1285 continue;
1286 SmallVector<InstrProfValueData, 2> SortedCallTargets =
1287 SortCallTargets(T.get());
1288 uint64_t Sum;
1289 findIndirectCallFunctionSamples(I, Sum);
1290 annotateValueSite(*I.getParent()->getParent()->getParent(), I,
1291 SortedCallTargets, Sum, IPVK_IndirectCallTarget,
1292 SortedCallTargets.size());
1293 } else if (!dyn_cast<IntrinsicInst>(&I)) {
1294 SmallVector<uint32_t, 1> Weights;
1295 Weights.push_back(BlockWeights[BB]);
1296 I.setMetadata(LLVMContext::MD_prof, MDB.createBranchWeights(Weights));
1297 }
1298 }
1299 }
1300 Instruction *TI = BB->getTerminator();
1301 if (TI->getNumSuccessors() == 1)
1302 continue;
1303 if (!isa<BranchInst>(TI) && !isa<SwitchInst>(TI))
1304 continue;
1305
1306 DebugLoc BranchLoc = TI->getDebugLoc();
1307 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)
1308 << ((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)
1309 : 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)
1310 << ".\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)
;
1311 SmallVector<uint32_t, 4> Weights;
1312 uint32_t MaxWeight = 0;
1313 Instruction *MaxDestInst;
1314 for (unsigned I = 0; I < TI->getNumSuccessors(); ++I) {
1315 BasicBlock *Succ = TI->getSuccessor(I);
1316 Edge E = std::make_pair(BB, Succ);
1317 uint64_t Weight = EdgeWeights[E];
1318 LLVM_DEBUG(dbgs() << "\t"; printEdgeWeight(dbgs(), E))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("sample-profile")) { dbgs() << "\t"; printEdgeWeight(dbgs
(), E); } } while (false)
;
1319 // Use uint32_t saturated arithmetic to adjust the incoming weights,
1320 // if needed. Sample counts in profiles are 64-bit unsigned values,
1321 // but internally branch weights are expressed as 32-bit values.
1322 if (Weight > std::numeric_limits<uint32_t>::max()) {
1323 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)
;
1324 Weight = std::numeric_limits<uint32_t>::max();
1325 }
1326 // Weight is added by one to avoid propagation errors introduced by
1327 // 0 weights.
1328 Weights.push_back(static_cast<uint32_t>(Weight + 1));
1329 if (Weight != 0) {
1330 if (Weight > MaxWeight) {
1331 MaxWeight = Weight;
1332 MaxDestInst = Succ->getFirstNonPHIOrDbgOrLifetime();
1333 }
1334 }
1335 }
1336
1337 uint64_t TempWeight;
1338 // Only set weights if there is at least one non-zero weight.
1339 // In any other case, let the analyzer set weights.
1340 // Do not set weights if the weights are present. In ThinLTO, the profile
1341 // annotation is done twice. If the first annotation already set the
1342 // weights, the second pass does not need to set it.
1343 if (MaxWeight > 0 && !TI->extractProfTotalWeight(TempWeight)) {
1344 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)
;
1345 TI->setMetadata(LLVMContext::MD_prof,
1346 MDB.createBranchWeights(Weights));
1347 ORE->emit([&]() {
1348 return OptimizationRemark(DEBUG_TYPE"sample-profile", "PopularDest", MaxDestInst)
1349 << "most popular destination for conditional branches at "
1350 << ore::NV("CondBranchesLoc", BranchLoc);
1351 });
1352 } else {
1353 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)
;
1354 }
1355 }
1356}
1357
1358/// Get the line number for the function header.
1359///
1360/// This looks up function \p F in the current compilation unit and
1361/// retrieves the line number where the function is defined. This is
1362/// line 0 for all the samples read from the profile file. Every line
1363/// number is relative to this line.
1364///
1365/// \param F Function object to query.
1366///
1367/// \returns the line number where \p F is defined. If it returns 0,
1368/// it means that there is no debug information available for \p F.
1369unsigned SampleProfileLoader::getFunctionLoc(Function &F) {
1370 if (DISubprogram *S = F.getSubprogram())
1371 return S->getLine();
1372
1373 if (NoWarnSampleUnused)
1374 return 0;
1375
1376 // If the start of \p F is missing, emit a diagnostic to inform the user
1377 // about the missed opportunity.
1378 F.getContext().diagnose(DiagnosticInfoSampleProfile(
1379 "No debug information found in function " + F.getName() +
1380 ": Function profile not used",
1381 DS_Warning));
1382 return 0;
1383}
1384
1385void SampleProfileLoader::computeDominanceAndLoopInfo(Function &F) {
1386 DT.reset(new DominatorTree);
1387 DT->recalculate(F);
1388
1389 PDT.reset(new PostDominatorTree(F));
1390
1391 LI.reset(new LoopInfo);
1392 LI->analyze(*DT);
1393}
1394
1395/// Generate branch weight metadata for all branches in \p F.
1396///
1397/// Branch weights are computed out of instruction samples using a
1398/// propagation heuristic. Propagation proceeds in 3 phases:
1399///
1400/// 1- Assignment of block weights. All the basic blocks in the function
1401/// are initial assigned the same weight as their most frequently
1402/// executed instruction.
1403///
1404/// 2- Creation of equivalence classes. Since samples may be missing from
1405/// blocks, we can fill in the gaps by setting the weights of all the
1406/// blocks in the same equivalence class to the same weight. To compute
1407/// the concept of equivalence, we use dominance and loop information.
1408/// Two blocks B1 and B2 are in the same equivalence class if B1
1409/// dominates B2, B2 post-dominates B1 and both are in the same loop.
1410///
1411/// 3- Propagation of block weights into edges. This uses a simple
1412/// propagation heuristic. The following rules are applied to every
1413/// block BB in the CFG:
1414///
1415/// - If BB has a single predecessor/successor, then the weight
1416/// of that edge is the weight of the block.
1417///
1418/// - If all the edges are known except one, and the weight of the
1419/// block is already known, the weight of the unknown edge will
1420/// be the weight of the block minus the sum of all the known
1421/// edges. If the sum of all the known edges is larger than BB's weight,
1422/// we set the unknown edge weight to zero.
1423///
1424/// - If there is a self-referential edge, and the weight of the block is
1425/// known, the weight for that edge is set to the weight of the block
1426/// minus the weight of the other incoming edges to that block (if
1427/// known).
1428///
1429/// Since this propagation is not guaranteed to finalize for every CFG, we
1430/// only allow it to proceed for a limited number of iterations (controlled
1431/// by -sample-profile-max-propagate-iterations).
1432///
1433/// FIXME: Try to replace this propagation heuristic with a scheme
1434/// that is guaranteed to finalize. A work-list approach similar to
1435/// the standard value propagation algorithm used by SSA-CCP might
1436/// work here.
1437///
1438/// Once all the branch weights are computed, we emit the MD_prof
1439/// metadata on BB using the computed values for each of its branches.
1440///
1441/// \param F The function to query.
1442///
1443/// \returns true if \p F was modified. Returns false, otherwise.
1444bool SampleProfileLoader::emitAnnotations(Function &F) {
1445 bool Changed = false;
1446
1447 if (getFunctionLoc(F) == 0)
1448 return false;
1449
1450 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)
1451 << 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)
;
1452
1453 DenseSet<GlobalValue::GUID> InlinedGUIDs;
1454 Changed |= inlineHotFunctions(F, InlinedGUIDs);
1455
1456 // Compute basic block weights.
1457 Changed |= computeBlockWeights(F);
1458
1459 if (Changed) {
1460 // Add an entry count to the function using the samples gathered at the
1461 // function entry.
1462 // Sets the GUIDs that are inlined in the profiled binary. This is used
1463 // for ThinLink to make correct liveness analysis, and also make the IR
1464 // match the profiled binary before annotation.
1465 F.setEntryCount(
1466 ProfileCount(Samples->getHeadSamples() + 1, Function::PCT_Real),
1467 &InlinedGUIDs);
1468
1469 // Compute dominance and loop info needed for propagation.
1470 computeDominanceAndLoopInfo(F);
1471
1472 // Find equivalence classes.
1473 findEquivalenceClasses(F);
1474
1475 // Propagate weights to all edges.
1476 propagateWeights(F);
1477 }
1478
1479 // If coverage checking was requested, compute it now.
1480 if (SampleProfileRecordCoverage) {
1481 unsigned Used = CoverageTracker.countUsedRecords(Samples, PSI);
1482 unsigned Total = CoverageTracker.countBodyRecords(Samples, PSI);
1483 unsigned Coverage = CoverageTracker.computeCoverage(Used, Total);
1484 if (Coverage < SampleProfileRecordCoverage) {
1485 F.getContext().diagnose(DiagnosticInfoSampleProfile(
1486 F.getSubprogram()->getFilename(), getFunctionLoc(F),
1487 Twine(Used) + " of " + Twine(Total) + " available profile records (" +
1488 Twine(Coverage) + "%) were applied",
1489 DS_Warning));
1490 }
1491 }
1492
1493 if (SampleProfileSampleCoverage) {
1494 uint64_t Used = CoverageTracker.getTotalUsedSamples();
1495 uint64_t Total = CoverageTracker.countBodySamples(Samples, PSI);
1496 unsigned Coverage = CoverageTracker.computeCoverage(Used, Total);
1497 if (Coverage < SampleProfileSampleCoverage) {
1498 F.getContext().diagnose(DiagnosticInfoSampleProfile(
1499 F.getSubprogram()->getFilename(), getFunctionLoc(F),
1500 Twine(Used) + " of " + Twine(Total) + " available profile samples (" +
1501 Twine(Coverage) + "%) were applied",
1502 DS_Warning));
1503 }
1504 }
1505 return Changed;
1506}
1507
1508char SampleProfileLoaderLegacyPass::ID = 0;
1509
1510INITIALIZE_PASS_BEGIN(SampleProfileLoaderLegacyPass, "sample-profile",static void *initializeSampleProfileLoaderLegacyPassPassOnce(
PassRegistry &Registry) {
1511 "Sample Profile loader", false, false)static void *initializeSampleProfileLoaderLegacyPassPassOnce(
PassRegistry &Registry) {
1512INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)initializeAssumptionCacheTrackerPass(Registry);
1513INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)initializeTargetTransformInfoWrapperPassPass(Registry);
1514INITIALIZE_PASS_DEPENDENCY(ProfileSummaryInfoWrapperPass)initializeProfileSummaryInfoWrapperPassPass(Registry);
1515INITIALIZE_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
)); }
1516 "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
)); }
1517
1518bool SampleProfileLoader::doInitialization(Module &M) {
1519 auto &Ctx = M.getContext();
1520 auto ReaderOrErr = SampleProfileReader::create(Filename, Ctx);
1521 if (std::error_code EC = ReaderOrErr.getError()) {
1522 std::string Msg = "Could not open profile: " + EC.message();
1523 Ctx.diagnose(DiagnosticInfoSampleProfile(Filename, Msg));
1524 return false;
1525 }
1526 Reader = std::move(ReaderOrErr.get());
1527 Reader->collectFuncsToUse(M);
1528 ProfileIsValid = (Reader->read() == sampleprof_error::success);
1529
1530 if (!RemappingFilename.empty()) {
1531 // Apply profile remappings to the loaded profile data if requested.
1532 // For now, we only support remapping symbols encoded using the Itanium
1533 // C++ ABI's name mangling scheme.
1534 ReaderOrErr = SampleProfileReaderItaniumRemapper::create(
1535 RemappingFilename, Ctx, std::move(Reader));
1536 if (std::error_code EC = ReaderOrErr.getError()) {
1537 std::string Msg = "Could not open profile remapping file: " + EC.message();
1538 Ctx.diagnose(DiagnosticInfoSampleProfile(Filename, Msg));
1539 return false;
1540 }
1541 Reader = std::move(ReaderOrErr.get());
1542 ProfileIsValid = (Reader->read() == sampleprof_error::success);
1543 }
1544 return true;
1545}
1546
1547ModulePass *llvm::createSampleProfileLoaderPass() {
1548 return new SampleProfileLoaderLegacyPass();
1549}
1550
1551ModulePass *llvm::createSampleProfileLoaderPass(StringRef Name) {
1552 return new SampleProfileLoaderLegacyPass(Name);
1553}
1554
1555bool SampleProfileLoader::runOnModule(Module &M, ModuleAnalysisManager *AM,
1556 ProfileSummaryInfo *_PSI) {
1557 FunctionSamples::GUIDToFuncNameMapper Mapper(M);
1558 if (!ProfileIsValid)
1559 return false;
1560
1561 PSI = _PSI;
1562 if (M.getProfileSummary() == nullptr)
1563 M.setProfileSummary(Reader->getSummary().getMD(M.getContext()));
1564
1565 // Compute the total number of samples collected in this profile.
1566 for (const auto &I : Reader->getProfiles())
1567 TotalCollectedSamples += I.second.getTotalSamples();
1568
1569 // Populate the symbol map.
1570 for (const auto &N_F : M.getValueSymbolTable()) {
1571 StringRef OrigName = N_F.getKey();
1572 Function *F = dyn_cast<Function>(N_F.getValue());
1573 if (F == nullptr)
1574 continue;
1575 SymbolMap[OrigName] = F;
1576 auto pos = OrigName.find('.');
1577 if (pos != StringRef::npos) {
1578 StringRef NewName = OrigName.substr(0, pos);
1579 auto r = SymbolMap.insert(std::make_pair(NewName, F));
1580 // Failiing to insert means there is already an entry in SymbolMap,
1581 // thus there are multiple functions that are mapped to the same
1582 // stripped name. In this case of name conflicting, set the value
1583 // to nullptr to avoid confusion.
1584 if (!r.second)
1585 r.first->second = nullptr;
1586 }
1587 }
1588
1589 bool retval = false;
1590 for (auto &F : M)
1591 if (!F.isDeclaration()) {
1592 clearFunctionData();
1593 retval |= runOnFunction(F, AM);
1594 }
1595 return retval;
1596}
1597
1598bool SampleProfileLoaderLegacyPass::runOnModule(Module &M) {
1599 ACT = &getAnalysis<AssumptionCacheTracker>();
1600 TTIWP = &getAnalysis<TargetTransformInfoWrapperPass>();
1601 ProfileSummaryInfo *PSI =
1602 getAnalysis<ProfileSummaryInfoWrapperPass>().getPSI();
1603 return SampleLoader.runOnModule(M, nullptr, PSI);
1604}
1605
1606bool SampleProfileLoader::runOnFunction(Function &F, ModuleAnalysisManager *AM) {
1607 // Initialize the entry count to -1, which will be treated conservatively
1608 // by getEntryCount as the same as unknown (None). If we have samples this
1609 // will be overwritten in emitAnnotations.
1610 F.setEntryCount(ProfileCount(-1, Function::PCT_Real));
1611 std::unique_ptr<OptimizationRemarkEmitter> OwnedORE;
1612 if (AM) {
1613 auto &FAM =
1614 AM->getResult<FunctionAnalysisManagerModuleProxy>(*F.getParent())
1615 .getManager();
1616 ORE = &FAM.getResult<OptimizationRemarkEmitterAnalysis>(F);
1617 } else {
1618 OwnedORE = make_unique<OptimizationRemarkEmitter>(&F);
1619 ORE = OwnedORE.get();
1620 }
1621 Samples = Reader->getSamplesFor(F);
1622 if (Samples && !Samples->empty())
1623 return emitAnnotations(F);
1624 return false;
1625}
1626
1627PreservedAnalyses SampleProfileLoaderPass::run(Module &M,
1628 ModuleAnalysisManager &AM) {
1629 FunctionAnalysisManager &FAM =
1630 AM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
1631
1632 auto GetAssumptionCache = [&](Function &F) -> AssumptionCache & {
1633 return FAM.getResult<AssumptionAnalysis>(F);
1634 };
1635 auto GetTTI = [&](Function &F) -> TargetTransformInfo & {
1636 return FAM.getResult<TargetIRAnalysis>(F);
1637 };
1638
1639 SampleProfileLoader SampleLoader(
1640 ProfileFileName.empty() ? SampleProfileFile : ProfileFileName,
1641 ProfileRemappingFileName.empty() ? SampleProfileRemappingFile
1642 : ProfileRemappingFileName,
1643 IsThinLTOPreLink, GetAssumptionCache, GetTTI);
1644
1645 SampleLoader.doInitialization(M);
1646
1647 ProfileSummaryInfo *PSI = &AM.getResult<ProfileSummaryAnalysis>(M);
1648 if (!SampleLoader.runOnModule(M, &AM, PSI))
1649 return PreservedAnalyses::all();
1650
1651 return PreservedAnalyses::none();
1652}