1 //===- SampleProfile.cpp - Incorporate sample profiles into the IR --------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file implements the SampleProfileLoader transformation. This pass
10 // reads a profile file generated by a sampling profiler (e.g. Linux Perf -
11 // http://perf.wiki.kernel.org/) and generates IR metadata to reflect the
12 // profile information in the given profile.
13 //
14 // This pass generates branch weight annotations on the IR:
15 //
16 // - prof: Represents branch weights. This annotation is added to branches
17 // to indicate the weights of each edge coming out of the branch.
18 // The weight of each edge is the weight of the target block for
19 // that edge. The weight of a block B is computed as the maximum
20 // number of samples found in B.
21 //
22 //===----------------------------------------------------------------------===//
23
24 #include "llvm/Transforms/IPO/SampleProfile.h"
25 #include "llvm/ADT/ArrayRef.h"
26 #include "llvm/ADT/DenseMap.h"
27 #include "llvm/ADT/DenseSet.h"
28 #include "llvm/ADT/None.h"
29 #include "llvm/ADT/SCCIterator.h"
30 #include "llvm/ADT/SmallPtrSet.h"
31 #include "llvm/ADT/SmallSet.h"
32 #include "llvm/ADT/SmallVector.h"
33 #include "llvm/ADT/Statistic.h"
34 #include "llvm/ADT/StringMap.h"
35 #include "llvm/ADT/StringRef.h"
36 #include "llvm/ADT/Twine.h"
37 #include "llvm/Analysis/AssumptionCache.h"
38 #include "llvm/Analysis/CallGraph.h"
39 #include "llvm/Analysis/CallGraphSCCPass.h"
40 #include "llvm/Analysis/InlineAdvisor.h"
41 #include "llvm/Analysis/InlineCost.h"
42 #include "llvm/Analysis/LoopInfo.h"
43 #include "llvm/Analysis/OptimizationRemarkEmitter.h"
44 #include "llvm/Analysis/PostDominators.h"
45 #include "llvm/Analysis/ProfileSummaryInfo.h"
46 #include "llvm/Analysis/ReplayInlineAdvisor.h"
47 #include "llvm/Analysis/TargetLibraryInfo.h"
48 #include "llvm/Analysis/TargetTransformInfo.h"
49 #include "llvm/IR/BasicBlock.h"
50 #include "llvm/IR/CFG.h"
51 #include "llvm/IR/DebugInfoMetadata.h"
52 #include "llvm/IR/DebugLoc.h"
53 #include "llvm/IR/DiagnosticInfo.h"
54 #include "llvm/IR/Dominators.h"
55 #include "llvm/IR/Function.h"
56 #include "llvm/IR/GlobalValue.h"
57 #include "llvm/IR/InstrTypes.h"
58 #include "llvm/IR/Instruction.h"
59 #include "llvm/IR/Instructions.h"
60 #include "llvm/IR/IntrinsicInst.h"
61 #include "llvm/IR/LLVMContext.h"
62 #include "llvm/IR/MDBuilder.h"
63 #include "llvm/IR/Module.h"
64 #include "llvm/IR/PassManager.h"
65 #include "llvm/IR/ValueSymbolTable.h"
66 #include "llvm/InitializePasses.h"
67 #include "llvm/Pass.h"
68 #include "llvm/ProfileData/InstrProf.h"
69 #include "llvm/ProfileData/SampleProf.h"
70 #include "llvm/ProfileData/SampleProfReader.h"
71 #include "llvm/Support/Casting.h"
72 #include "llvm/Support/CommandLine.h"
73 #include "llvm/Support/Debug.h"
74 #include "llvm/Support/ErrorHandling.h"
75 #include "llvm/Support/ErrorOr.h"
76 #include "llvm/Support/GenericDomTree.h"
77 #include "llvm/Support/raw_ostream.h"
78 #include "llvm/Transforms/IPO.h"
79 #include "llvm/Transforms/Instrumentation.h"
80 #include "llvm/Transforms/Utils/CallPromotionUtils.h"
81 #include "llvm/Transforms/Utils/Cloning.h"
82 #include "llvm/Transforms/Utils/MisExpect.h"
83 #include <algorithm>
84 #include <cassert>
85 #include <cstdint>
86 #include <functional>
87 #include <limits>
88 #include <map>
89 #include <memory>
90 #include <queue>
91 #include <string>
92 #include <system_error>
93 #include <utility>
94 #include <vector>
95
96 using namespace llvm;
97 using namespace sampleprof;
98 using ProfileCount = Function::ProfileCount;
99 #define DEBUG_TYPE "sample-profile"
100 #define CSINLINE_DEBUG DEBUG_TYPE "-inline"
101
102 STATISTIC(NumCSInlined,
103 "Number of functions inlined with context sensitive profile");
104 STATISTIC(NumCSNotInlined,
105 "Number of functions not inlined with context sensitive profile");
106
107 // Command line option to specify the file to read samples from. This is
108 // mainly used for debugging.
109 static cl::opt<std::string> SampleProfileFile(
110 "sample-profile-file", cl::init(""), cl::value_desc("filename"),
111 cl::desc("Profile file loaded by -sample-profile"), cl::Hidden);
112
113 // The named file contains a set of transformations that may have been applied
114 // to the symbol names between the program from which the sample data was
115 // collected and the current program's symbols.
116 static cl::opt<std::string> SampleProfileRemappingFile(
117 "sample-profile-remapping-file", cl::init(""), cl::value_desc("filename"),
118 cl::desc("Profile remapping file loaded by -sample-profile"), cl::Hidden);
119
120 static cl::opt<unsigned> SampleProfileMaxPropagateIterations(
121 "sample-profile-max-propagate-iterations", cl::init(100),
122 cl::desc("Maximum number of iterations to go through when propagating "
123 "sample block/edge weights through the CFG."));
124
125 static cl::opt<unsigned> SampleProfileRecordCoverage(
126 "sample-profile-check-record-coverage", cl::init(0), cl::value_desc("N"),
127 cl::desc("Emit a warning if less than N% of records in the input profile "
128 "are matched to the IR."));
129
130 static cl::opt<unsigned> SampleProfileSampleCoverage(
131 "sample-profile-check-sample-coverage", cl::init(0), cl::value_desc("N"),
132 cl::desc("Emit a warning if less than N% of samples in the input profile "
133 "are matched to the IR."));
134
135 static cl::opt<bool> NoWarnSampleUnused(
136 "no-warn-sample-unused", cl::init(false), cl::Hidden,
137 cl::desc("Use this option to turn off/on warnings about function with "
138 "samples but without debug information to use those samples. "));
139
140 static cl::opt<bool> ProfileSampleAccurate(
141 "profile-sample-accurate", cl::Hidden, cl::init(false),
142 cl::desc("If the sample profile is accurate, we will mark all un-sampled "
143 "callsite and function as having 0 samples. Otherwise, treat "
144 "un-sampled callsites and functions conservatively as unknown. "));
145
146 static cl::opt<bool> ProfileAccurateForSymsInList(
147 "profile-accurate-for-symsinlist", cl::Hidden, cl::ZeroOrMore,
148 cl::init(true),
149 cl::desc("For symbols in profile symbol list, regard their profiles to "
150 "be accurate. It may be overriden by profile-sample-accurate. "));
151
152 static cl::opt<bool> ProfileMergeInlinee(
153 "sample-profile-merge-inlinee", cl::Hidden, cl::init(true),
154 cl::desc("Merge past inlinee's profile to outline version if sample "
155 "profile loader decided not to inline a call site. It will "
156 "only be enabled when top-down order of profile loading is "
157 "enabled. "));
158
159 static cl::opt<bool> ProfileTopDownLoad(
160 "sample-profile-top-down-load", cl::Hidden, cl::init(true),
161 cl::desc("Do profile annotation and inlining for functions in top-down "
162 "order of call graph during sample profile loading. It only "
163 "works for new pass manager. "));
164
165 static cl::opt<bool> ProfileSizeInline(
166 "sample-profile-inline-size", cl::Hidden, cl::init(false),
167 cl::desc("Inline cold call sites in profile loader if it's beneficial "
168 "for code size."));
169
170 static cl::opt<int> SampleColdCallSiteThreshold(
171 "sample-profile-cold-inline-threshold", cl::Hidden, cl::init(45),
172 cl::desc("Threshold for inlining cold callsites"));
173
174 static cl::opt<std::string> ProfileInlineReplayFile(
175 "sample-profile-inline-replay", cl::init(""), cl::value_desc("filename"),
176 cl::desc(
177 "Optimization remarks file containing inline remarks to be replayed "
178 "by inlining from sample profile loader."),
179 cl::Hidden);
180
181 namespace {
182
183 using BlockWeightMap = DenseMap<const BasicBlock *, uint64_t>;
184 using EquivalenceClassMap = DenseMap<const BasicBlock *, const BasicBlock *>;
185 using Edge = std::pair<const BasicBlock *, const BasicBlock *>;
186 using EdgeWeightMap = DenseMap<Edge, uint64_t>;
187 using BlockEdgeMap =
188 DenseMap<const BasicBlock *, SmallVector<const BasicBlock *, 8>>;
189
190 class SampleProfileLoader;
191
192 class SampleCoverageTracker {
193 public:
SampleCoverageTracker(SampleProfileLoader & SPL)194 SampleCoverageTracker(SampleProfileLoader &SPL) : SPLoader(SPL){};
195
196 bool markSamplesUsed(const FunctionSamples *FS, uint32_t LineOffset,
197 uint32_t Discriminator, uint64_t Samples);
198 unsigned computeCoverage(unsigned Used, unsigned Total) const;
199 unsigned countUsedRecords(const FunctionSamples *FS,
200 ProfileSummaryInfo *PSI) const;
201 unsigned countBodyRecords(const FunctionSamples *FS,
202 ProfileSummaryInfo *PSI) const;
getTotalUsedSamples() const203 uint64_t getTotalUsedSamples() const { return TotalUsedSamples; }
204 uint64_t countBodySamples(const FunctionSamples *FS,
205 ProfileSummaryInfo *PSI) const;
206
clear()207 void clear() {
208 SampleCoverage.clear();
209 TotalUsedSamples = 0;
210 }
211
212 private:
213 using BodySampleCoverageMap = std::map<LineLocation, unsigned>;
214 using FunctionSamplesCoverageMap =
215 DenseMap<const FunctionSamples *, BodySampleCoverageMap>;
216
217 /// Coverage map for sampling records.
218 ///
219 /// This map keeps a record of sampling records that have been matched to
220 /// an IR instruction. This is used to detect some form of staleness in
221 /// profiles (see flag -sample-profile-check-coverage).
222 ///
223 /// Each entry in the map corresponds to a FunctionSamples instance. This is
224 /// another map that counts how many times the sample record at the
225 /// given location has been used.
226 FunctionSamplesCoverageMap SampleCoverage;
227
228 /// Number of samples used from the profile.
229 ///
230 /// When a sampling record is used for the first time, the samples from
231 /// that record are added to this accumulator. Coverage is later computed
232 /// based on the total number of samples available in this function and
233 /// its callsites.
234 ///
235 /// Note that this accumulator tracks samples used from a single function
236 /// and all the inlined callsites. Strictly, we should have a map of counters
237 /// keyed by FunctionSamples pointers, but these stats are cleared after
238 /// every function, so we just need to keep a single counter.
239 uint64_t TotalUsedSamples = 0;
240
241 SampleProfileLoader &SPLoader;
242 };
243
244 class GUIDToFuncNameMapper {
245 public:
GUIDToFuncNameMapper(Module & M,SampleProfileReader & Reader,DenseMap<uint64_t,StringRef> & GUIDToFuncNameMap)246 GUIDToFuncNameMapper(Module &M, SampleProfileReader &Reader,
247 DenseMap<uint64_t, StringRef> &GUIDToFuncNameMap)
248 : CurrentReader(Reader), CurrentModule(M),
249 CurrentGUIDToFuncNameMap(GUIDToFuncNameMap) {
250 if (!CurrentReader.useMD5())
251 return;
252
253 for (const auto &F : CurrentModule) {
254 StringRef OrigName = F.getName();
255 CurrentGUIDToFuncNameMap.insert(
256 {Function::getGUID(OrigName), OrigName});
257
258 // Local to global var promotion used by optimization like thinlto
259 // will rename the var and add suffix like ".llvm.xxx" to the
260 // original local name. In sample profile, the suffixes of function
261 // names are all stripped. Since it is possible that the mapper is
262 // built in post-thin-link phase and var promotion has been done,
263 // we need to add the substring of function name without the suffix
264 // into the GUIDToFuncNameMap.
265 StringRef CanonName = FunctionSamples::getCanonicalFnName(F);
266 if (CanonName != OrigName)
267 CurrentGUIDToFuncNameMap.insert(
268 {Function::getGUID(CanonName), CanonName});
269 }
270
271 // Update GUIDToFuncNameMap for each function including inlinees.
272 SetGUIDToFuncNameMapForAll(&CurrentGUIDToFuncNameMap);
273 }
274
~GUIDToFuncNameMapper()275 ~GUIDToFuncNameMapper() {
276 if (!CurrentReader.useMD5())
277 return;
278
279 CurrentGUIDToFuncNameMap.clear();
280
281 // Reset GUIDToFuncNameMap for of each function as they're no
282 // longer valid at this point.
283 SetGUIDToFuncNameMapForAll(nullptr);
284 }
285
286 private:
SetGUIDToFuncNameMapForAll(DenseMap<uint64_t,StringRef> * Map)287 void SetGUIDToFuncNameMapForAll(DenseMap<uint64_t, StringRef> *Map) {
288 std::queue<FunctionSamples *> FSToUpdate;
289 for (auto &IFS : CurrentReader.getProfiles()) {
290 FSToUpdate.push(&IFS.second);
291 }
292
293 while (!FSToUpdate.empty()) {
294 FunctionSamples *FS = FSToUpdate.front();
295 FSToUpdate.pop();
296 FS->GUIDToFuncNameMap = Map;
297 for (const auto &ICS : FS->getCallsiteSamples()) {
298 const FunctionSamplesMap &FSMap = ICS.second;
299 for (auto &IFS : FSMap) {
300 FunctionSamples &FS = const_cast<FunctionSamples &>(IFS.second);
301 FSToUpdate.push(&FS);
302 }
303 }
304 }
305 }
306
307 SampleProfileReader &CurrentReader;
308 Module &CurrentModule;
309 DenseMap<uint64_t, StringRef> &CurrentGUIDToFuncNameMap;
310 };
311
312 /// Sample profile pass.
313 ///
314 /// This pass reads profile data from the file specified by
315 /// -sample-profile-file and annotates every affected function with the
316 /// profile information found in that file.
317 class SampleProfileLoader {
318 public:
SampleProfileLoader(StringRef Name,StringRef RemapName,bool IsThinLTOPreLink,std::function<AssumptionCache & (Function &)> GetAssumptionCache,std::function<TargetTransformInfo & (Function &)> GetTargetTransformInfo,std::function<const TargetLibraryInfo & (Function &)> GetTLI)319 SampleProfileLoader(
320 StringRef Name, StringRef RemapName, bool IsThinLTOPreLink,
321 std::function<AssumptionCache &(Function &)> GetAssumptionCache,
322 std::function<TargetTransformInfo &(Function &)> GetTargetTransformInfo,
323 std::function<const TargetLibraryInfo &(Function &)> GetTLI)
324 : GetAC(std::move(GetAssumptionCache)),
325 GetTTI(std::move(GetTargetTransformInfo)), GetTLI(std::move(GetTLI)),
326 CoverageTracker(*this), Filename(std::string(Name)),
327 RemappingFilename(std::string(RemapName)),
328 IsThinLTOPreLink(IsThinLTOPreLink) {}
329
330 bool doInitialization(Module &M, FunctionAnalysisManager *FAM = nullptr);
331 bool runOnModule(Module &M, ModuleAnalysisManager *AM,
332 ProfileSummaryInfo *_PSI, CallGraph *CG);
333
dump()334 void dump() { Reader->dump(); }
335
336 protected:
337 friend class SampleCoverageTracker;
338
339 bool runOnFunction(Function &F, ModuleAnalysisManager *AM);
340 unsigned getFunctionLoc(Function &F);
341 bool emitAnnotations(Function &F);
342 ErrorOr<uint64_t> getInstWeight(const Instruction &I);
343 ErrorOr<uint64_t> getBlockWeight(const BasicBlock *BB);
344 const FunctionSamples *findCalleeFunctionSamples(const CallBase &I) const;
345 std::vector<const FunctionSamples *>
346 findIndirectCallFunctionSamples(const Instruction &I, uint64_t &Sum) const;
347 mutable DenseMap<const DILocation *, const FunctionSamples *> DILocation2SampleMap;
348 const FunctionSamples *findFunctionSamples(const Instruction &I) const;
349 bool inlineCallInstruction(CallBase &CB);
350 bool inlineHotFunctions(Function &F,
351 DenseSet<GlobalValue::GUID> &InlinedGUIDs);
352 // Inline cold/small functions in addition to hot ones
353 bool shouldInlineColdCallee(CallBase &CallInst);
354 void emitOptimizationRemarksForInlineCandidates(
355 const SmallVectorImpl<CallBase *> &Candidates, const Function &F,
356 bool Hot);
357 void printEdgeWeight(raw_ostream &OS, Edge E);
358 void printBlockWeight(raw_ostream &OS, const BasicBlock *BB) const;
359 void printBlockEquivalence(raw_ostream &OS, const BasicBlock *BB);
360 bool computeBlockWeights(Function &F);
361 void findEquivalenceClasses(Function &F);
362 template <bool IsPostDom>
363 void findEquivalencesFor(BasicBlock *BB1, ArrayRef<BasicBlock *> Descendants,
364 DominatorTreeBase<BasicBlock, IsPostDom> *DomTree);
365
366 void propagateWeights(Function &F);
367 uint64_t visitEdge(Edge E, unsigned *NumUnknownEdges, Edge *UnknownEdge);
368 void buildEdges(Function &F);
369 std::vector<Function *> buildFunctionOrder(Module &M, CallGraph *CG);
370 bool propagateThroughEdges(Function &F, bool UpdateBlockCount);
371 void computeDominanceAndLoopInfo(Function &F);
372 void clearFunctionData();
373 bool callsiteIsHot(const FunctionSamples *CallsiteFS,
374 ProfileSummaryInfo *PSI);
375
376 /// Map basic blocks to their computed weights.
377 ///
378 /// The weight of a basic block is defined to be the maximum
379 /// of all the instruction weights in that block.
380 BlockWeightMap BlockWeights;
381
382 /// Map edges to their computed weights.
383 ///
384 /// Edge weights are computed by propagating basic block weights in
385 /// SampleProfile::propagateWeights.
386 EdgeWeightMap EdgeWeights;
387
388 /// Set of visited blocks during propagation.
389 SmallPtrSet<const BasicBlock *, 32> VisitedBlocks;
390
391 /// Set of visited edges during propagation.
392 SmallSet<Edge, 32> VisitedEdges;
393
394 /// Equivalence classes for block weights.
395 ///
396 /// Two blocks BB1 and BB2 are in the same equivalence class if they
397 /// dominate and post-dominate each other, and they are in the same loop
398 /// nest. When this happens, the two blocks are guaranteed to execute
399 /// the same number of times.
400 EquivalenceClassMap EquivalenceClass;
401
402 /// Map from function name to Function *. Used to find the function from
403 /// the function name. If the function name contains suffix, additional
404 /// entry is added to map from the stripped name to the function if there
405 /// is one-to-one mapping.
406 StringMap<Function *> SymbolMap;
407
408 /// Dominance, post-dominance and loop information.
409 std::unique_ptr<DominatorTree> DT;
410 std::unique_ptr<PostDominatorTree> PDT;
411 std::unique_ptr<LoopInfo> LI;
412
413 std::function<AssumptionCache &(Function &)> GetAC;
414 std::function<TargetTransformInfo &(Function &)> GetTTI;
415 std::function<const TargetLibraryInfo &(Function &)> GetTLI;
416
417 /// Predecessors for each basic block in the CFG.
418 BlockEdgeMap Predecessors;
419
420 /// Successors for each basic block in the CFG.
421 BlockEdgeMap Successors;
422
423 SampleCoverageTracker CoverageTracker;
424
425 /// Profile reader object.
426 std::unique_ptr<SampleProfileReader> Reader;
427
428 /// Samples collected for the body of this function.
429 FunctionSamples *Samples = nullptr;
430
431 /// Name of the profile file to load.
432 std::string Filename;
433
434 /// Name of the profile remapping file to load.
435 std::string RemappingFilename;
436
437 /// Flag indicating whether the profile input loaded successfully.
438 bool ProfileIsValid = false;
439
440 /// Flag indicating if the pass is invoked in ThinLTO compile phase.
441 ///
442 /// In this phase, in annotation, we should not promote indirect calls.
443 /// Instead, we will mark GUIDs that needs to be annotated to the function.
444 bool IsThinLTOPreLink;
445
446 /// Profile Summary Info computed from sample profile.
447 ProfileSummaryInfo *PSI = nullptr;
448
449 /// Profle Symbol list tells whether a function name appears in the binary
450 /// used to generate the current profile.
451 std::unique_ptr<ProfileSymbolList> PSL;
452
453 /// Total number of samples collected in this profile.
454 ///
455 /// This is the sum of all the samples collected in all the functions executed
456 /// at runtime.
457 uint64_t TotalCollectedSamples = 0;
458
459 /// Optimization Remark Emitter used to emit diagnostic remarks.
460 OptimizationRemarkEmitter *ORE = nullptr;
461
462 // Information recorded when we declined to inline a call site
463 // because we have determined it is too cold is accumulated for
464 // each callee function. Initially this is just the entry count.
465 struct NotInlinedProfileInfo {
466 uint64_t entryCount;
467 };
468 DenseMap<Function *, NotInlinedProfileInfo> notInlinedCallInfo;
469
470 // GUIDToFuncNameMap saves the mapping from GUID to the symbol name, for
471 // all the function symbols defined or declared in current module.
472 DenseMap<uint64_t, StringRef> GUIDToFuncNameMap;
473
474 // All the Names used in FunctionSamples including outline function
475 // names, inline instance names and call target names.
476 StringSet<> NamesInProfile;
477
478 // For symbol in profile symbol list, whether to regard their profiles
479 // to be accurate. It is mainly decided by existance of profile symbol
480 // list and -profile-accurate-for-symsinlist flag, but it can be
481 // overriden by -profile-sample-accurate or profile-sample-accurate
482 // attribute.
483 bool ProfAccForSymsInList;
484
485 // External inline advisor used to replay inline decision from remarks.
486 std::unique_ptr<ReplayInlineAdvisor> ExternalInlineAdvisor;
487 };
488
489 class SampleProfileLoaderLegacyPass : public ModulePass {
490 public:
491 // Class identification, replacement for typeinfo
492 static char ID;
493
SampleProfileLoaderLegacyPass(StringRef Name=SampleProfileFile,bool IsThinLTOPreLink=false)494 SampleProfileLoaderLegacyPass(StringRef Name = SampleProfileFile,
495 bool IsThinLTOPreLink = false)
496 : ModulePass(ID), SampleLoader(
497 Name, SampleProfileRemappingFile, IsThinLTOPreLink,
498 [&](Function &F) -> AssumptionCache & {
499 return ACT->getAssumptionCache(F);
500 },
__anon58e702310302(Function &F) 501 [&](Function &F) -> TargetTransformInfo & {
502 return TTIWP->getTTI(F);
503 },
__anon58e702310402(Function &F) 504 [&](Function &F) -> TargetLibraryInfo & {
505 return TLIWP->getTLI(F);
506 }) {
507 initializeSampleProfileLoaderLegacyPassPass(
508 *PassRegistry::getPassRegistry());
509 }
510
dump()511 void dump() { SampleLoader.dump(); }
512
doInitialization(Module & M)513 bool doInitialization(Module &M) override {
514 return SampleLoader.doInitialization(M);
515 }
516
getPassName() const517 StringRef getPassName() const override { return "Sample profile pass"; }
518 bool runOnModule(Module &M) override;
519
getAnalysisUsage(AnalysisUsage & AU) const520 void getAnalysisUsage(AnalysisUsage &AU) const override {
521 AU.addRequired<AssumptionCacheTracker>();
522 AU.addRequired<TargetTransformInfoWrapperPass>();
523 AU.addRequired<TargetLibraryInfoWrapperPass>();
524 AU.addRequired<ProfileSummaryInfoWrapperPass>();
525 }
526
527 private:
528 SampleProfileLoader SampleLoader;
529 AssumptionCacheTracker *ACT = nullptr;
530 TargetTransformInfoWrapperPass *TTIWP = nullptr;
531 TargetLibraryInfoWrapperPass *TLIWP = nullptr;
532 };
533
534 } // end anonymous namespace
535
536 /// Return true if the given callsite is hot wrt to hot cutoff threshold.
537 ///
538 /// Functions that were inlined in the original binary will be represented
539 /// in the inline stack in the sample profile. If the profile shows that
540 /// the original inline decision was "good" (i.e., the callsite is executed
541 /// frequently), then we will recreate the inline decision and apply the
542 /// profile from the inlined callsite.
543 ///
544 /// To decide whether an inlined callsite is hot, we compare the callsite
545 /// sample count with the hot cutoff computed by ProfileSummaryInfo, it is
546 /// regarded as hot if the count is above the cutoff value.
547 ///
548 /// When ProfileAccurateForSymsInList is enabled and profile symbol list
549 /// is present, functions in the profile symbol list but without profile will
550 /// be regarded as cold and much less inlining will happen in CGSCC inlining
551 /// pass, so we tend to lower the hot criteria here to allow more early
552 /// inlining to happen for warm callsites and it is helpful for performance.
callsiteIsHot(const FunctionSamples * CallsiteFS,ProfileSummaryInfo * PSI)553 bool SampleProfileLoader::callsiteIsHot(const FunctionSamples *CallsiteFS,
554 ProfileSummaryInfo *PSI) {
555 if (!CallsiteFS)
556 return false; // The callsite was not inlined in the original binary.
557
558 assert(PSI && "PSI is expected to be non null");
559 uint64_t CallsiteTotalSamples = CallsiteFS->getTotalSamples();
560 if (ProfAccForSymsInList)
561 return !PSI->isColdCount(CallsiteTotalSamples);
562 else
563 return PSI->isHotCount(CallsiteTotalSamples);
564 }
565
566 /// Mark as used the sample record for the given function samples at
567 /// (LineOffset, Discriminator).
568 ///
569 /// \returns true if this is the first time we mark the given record.
markSamplesUsed(const FunctionSamples * FS,uint32_t LineOffset,uint32_t Discriminator,uint64_t Samples)570 bool SampleCoverageTracker::markSamplesUsed(const FunctionSamples *FS,
571 uint32_t LineOffset,
572 uint32_t Discriminator,
573 uint64_t Samples) {
574 LineLocation Loc(LineOffset, Discriminator);
575 unsigned &Count = SampleCoverage[FS][Loc];
576 bool FirstTime = (++Count == 1);
577 if (FirstTime)
578 TotalUsedSamples += Samples;
579 return FirstTime;
580 }
581
582 /// Return the number of sample records that were applied from this profile.
583 ///
584 /// This count does not include records from cold inlined callsites.
585 unsigned
countUsedRecords(const FunctionSamples * FS,ProfileSummaryInfo * PSI) const586 SampleCoverageTracker::countUsedRecords(const FunctionSamples *FS,
587 ProfileSummaryInfo *PSI) const {
588 auto I = SampleCoverage.find(FS);
589
590 // The size of the coverage map for FS represents the number of records
591 // that were marked used at least once.
592 unsigned Count = (I != SampleCoverage.end()) ? I->second.size() : 0;
593
594 // If there are inlined callsites in this function, count the samples found
595 // in the respective bodies. However, do not bother counting callees with 0
596 // total samples, these are callees that were never invoked at runtime.
597 for (const auto &I : FS->getCallsiteSamples())
598 for (const auto &J : I.second) {
599 const FunctionSamples *CalleeSamples = &J.second;
600 if (SPLoader.callsiteIsHot(CalleeSamples, PSI))
601 Count += countUsedRecords(CalleeSamples, PSI);
602 }
603
604 return Count;
605 }
606
607 /// Return the number of sample records in the body of this profile.
608 ///
609 /// This count does not include records from cold inlined callsites.
610 unsigned
countBodyRecords(const FunctionSamples * FS,ProfileSummaryInfo * PSI) const611 SampleCoverageTracker::countBodyRecords(const FunctionSamples *FS,
612 ProfileSummaryInfo *PSI) const {
613 unsigned Count = FS->getBodySamples().size();
614
615 // Only count records in hot callsites.
616 for (const auto &I : FS->getCallsiteSamples())
617 for (const auto &J : I.second) {
618 const FunctionSamples *CalleeSamples = &J.second;
619 if (SPLoader.callsiteIsHot(CalleeSamples, PSI))
620 Count += countBodyRecords(CalleeSamples, PSI);
621 }
622
623 return Count;
624 }
625
626 /// Return the number of samples collected in the body of this profile.
627 ///
628 /// This count does not include samples from cold inlined callsites.
629 uint64_t
countBodySamples(const FunctionSamples * FS,ProfileSummaryInfo * PSI) const630 SampleCoverageTracker::countBodySamples(const FunctionSamples *FS,
631 ProfileSummaryInfo *PSI) const {
632 uint64_t Total = 0;
633 for (const auto &I : FS->getBodySamples())
634 Total += I.second.getSamples();
635
636 // Only count samples in hot callsites.
637 for (const auto &I : FS->getCallsiteSamples())
638 for (const auto &J : I.second) {
639 const FunctionSamples *CalleeSamples = &J.second;
640 if (SPLoader.callsiteIsHot(CalleeSamples, PSI))
641 Total += countBodySamples(CalleeSamples, PSI);
642 }
643
644 return Total;
645 }
646
647 /// Return the fraction of sample records used in this profile.
648 ///
649 /// The returned value is an unsigned integer in the range 0-100 indicating
650 /// the percentage of sample records that were used while applying this
651 /// profile to the associated function.
computeCoverage(unsigned Used,unsigned Total) const652 unsigned SampleCoverageTracker::computeCoverage(unsigned Used,
653 unsigned Total) const {
654 assert(Used <= Total &&
655 "number of used records cannot exceed the total number of records");
656 return Total > 0 ? Used * 100 / Total : 100;
657 }
658
659 /// Clear all the per-function data used to load samples and propagate weights.
clearFunctionData()660 void SampleProfileLoader::clearFunctionData() {
661 BlockWeights.clear();
662 EdgeWeights.clear();
663 VisitedBlocks.clear();
664 VisitedEdges.clear();
665 EquivalenceClass.clear();
666 DT = nullptr;
667 PDT = nullptr;
668 LI = nullptr;
669 Predecessors.clear();
670 Successors.clear();
671 CoverageTracker.clear();
672 }
673
674 #ifndef NDEBUG
675 /// Print the weight of edge \p E on stream \p OS.
676 ///
677 /// \param OS Stream to emit the output to.
678 /// \param E Edge to print.
printEdgeWeight(raw_ostream & OS,Edge E)679 void SampleProfileLoader::printEdgeWeight(raw_ostream &OS, Edge E) {
680 OS << "weight[" << E.first->getName() << "->" << E.second->getName()
681 << "]: " << EdgeWeights[E] << "\n";
682 }
683
684 /// Print the equivalence class of block \p BB on stream \p OS.
685 ///
686 /// \param OS Stream to emit the output to.
687 /// \param BB Block to print.
printBlockEquivalence(raw_ostream & OS,const BasicBlock * BB)688 void SampleProfileLoader::printBlockEquivalence(raw_ostream &OS,
689 const BasicBlock *BB) {
690 const BasicBlock *Equiv = EquivalenceClass[BB];
691 OS << "equivalence[" << BB->getName()
692 << "]: " << ((Equiv) ? EquivalenceClass[BB]->getName() : "NONE") << "\n";
693 }
694
695 /// Print the weight of block \p BB on stream \p OS.
696 ///
697 /// \param OS Stream to emit the output to.
698 /// \param BB Block to print.
printBlockWeight(raw_ostream & OS,const BasicBlock * BB) const699 void SampleProfileLoader::printBlockWeight(raw_ostream &OS,
700 const BasicBlock *BB) const {
701 const auto &I = BlockWeights.find(BB);
702 uint64_t W = (I == BlockWeights.end() ? 0 : I->second);
703 OS << "weight[" << BB->getName() << "]: " << W << "\n";
704 }
705 #endif
706
707 /// Get the weight for an instruction.
708 ///
709 /// The "weight" of an instruction \p Inst is the number of samples
710 /// collected on that instruction at runtime. To retrieve it, we
711 /// need to compute the line number of \p Inst relative to the start of its
712 /// function. We use HeaderLineno to compute the offset. We then
713 /// look up the samples collected for \p Inst using BodySamples.
714 ///
715 /// \param Inst Instruction to query.
716 ///
717 /// \returns the weight of \p Inst.
getInstWeight(const Instruction & Inst)718 ErrorOr<uint64_t> SampleProfileLoader::getInstWeight(const Instruction &Inst) {
719 const DebugLoc &DLoc = Inst.getDebugLoc();
720 if (!DLoc)
721 return std::error_code();
722
723 const FunctionSamples *FS = findFunctionSamples(Inst);
724 if (!FS)
725 return std::error_code();
726
727 // Ignore all intrinsics, phinodes and branch instructions.
728 // Branch and phinodes instruction usually contains debug info from sources outside of
729 // the residing basic block, thus we ignore them during annotation.
730 if (isa<BranchInst>(Inst) || isa<IntrinsicInst>(Inst) || isa<PHINode>(Inst))
731 return std::error_code();
732
733 // If a direct call/invoke instruction is inlined in profile
734 // (findCalleeFunctionSamples returns non-empty result), but not inlined here,
735 // it means that the inlined callsite has no sample, thus the call
736 // instruction should have 0 count.
737 if (auto *CB = dyn_cast<CallBase>(&Inst))
738 if (!CB->isIndirectCall() && findCalleeFunctionSamples(*CB))
739 return 0;
740
741 const DILocation *DIL = DLoc;
742 uint32_t LineOffset = FunctionSamples::getOffset(DIL);
743 uint32_t Discriminator = DIL->getBaseDiscriminator();
744 ErrorOr<uint64_t> R = FS->findSamplesAt(LineOffset, Discriminator);
745 if (R) {
746 bool FirstMark =
747 CoverageTracker.markSamplesUsed(FS, LineOffset, Discriminator, R.get());
748 if (FirstMark) {
749 ORE->emit([&]() {
750 OptimizationRemarkAnalysis Remark(DEBUG_TYPE, "AppliedSamples", &Inst);
751 Remark << "Applied " << ore::NV("NumSamples", *R);
752 Remark << " samples from profile (offset: ";
753 Remark << ore::NV("LineOffset", LineOffset);
754 if (Discriminator) {
755 Remark << ".";
756 Remark << ore::NV("Discriminator", Discriminator);
757 }
758 Remark << ")";
759 return Remark;
760 });
761 }
762 LLVM_DEBUG(dbgs() << " " << DLoc.getLine() << "."
763 << DIL->getBaseDiscriminator() << ":" << Inst
764 << " (line offset: " << LineOffset << "."
765 << DIL->getBaseDiscriminator() << " - weight: " << R.get()
766 << ")\n");
767 }
768 return R;
769 }
770
771 /// Compute the weight of a basic block.
772 ///
773 /// The weight of basic block \p BB is the maximum weight of all the
774 /// instructions in BB.
775 ///
776 /// \param BB The basic block to query.
777 ///
778 /// \returns the weight for \p BB.
getBlockWeight(const BasicBlock * BB)779 ErrorOr<uint64_t> SampleProfileLoader::getBlockWeight(const BasicBlock *BB) {
780 uint64_t Max = 0;
781 bool HasWeight = false;
782 for (auto &I : BB->getInstList()) {
783 const ErrorOr<uint64_t> &R = getInstWeight(I);
784 if (R) {
785 Max = std::max(Max, R.get());
786 HasWeight = true;
787 }
788 }
789 return HasWeight ? ErrorOr<uint64_t>(Max) : std::error_code();
790 }
791
792 /// Compute and store the weights of every basic block.
793 ///
794 /// This populates the BlockWeights map by computing
795 /// the weights of every basic block in the CFG.
796 ///
797 /// \param F The function to query.
computeBlockWeights(Function & F)798 bool SampleProfileLoader::computeBlockWeights(Function &F) {
799 bool Changed = false;
800 LLVM_DEBUG(dbgs() << "Block weights\n");
801 for (const auto &BB : F) {
802 ErrorOr<uint64_t> Weight = getBlockWeight(&BB);
803 if (Weight) {
804 BlockWeights[&BB] = Weight.get();
805 VisitedBlocks.insert(&BB);
806 Changed = true;
807 }
808 LLVM_DEBUG(printBlockWeight(dbgs(), &BB));
809 }
810
811 return Changed;
812 }
813
814 /// Get the FunctionSamples for a call instruction.
815 ///
816 /// The FunctionSamples of a call/invoke instruction \p Inst is the inlined
817 /// instance in which that call instruction is calling to. It contains
818 /// all samples that resides in the inlined instance. We first find the
819 /// inlined instance in which the call instruction is from, then we
820 /// traverse its children to find the callsite with the matching
821 /// location.
822 ///
823 /// \param Inst Call/Invoke instruction to query.
824 ///
825 /// \returns The FunctionSamples pointer to the inlined instance.
826 const FunctionSamples *
findCalleeFunctionSamples(const CallBase & Inst) const827 SampleProfileLoader::findCalleeFunctionSamples(const CallBase &Inst) const {
828 const DILocation *DIL = Inst.getDebugLoc();
829 if (!DIL) {
830 return nullptr;
831 }
832
833 StringRef CalleeName;
834 if (Function *Callee = Inst.getCalledFunction())
835 CalleeName = Callee->getName();
836
837 const FunctionSamples *FS = findFunctionSamples(Inst);
838 if (FS == nullptr)
839 return nullptr;
840
841 return FS->findFunctionSamplesAt(LineLocation(FunctionSamples::getOffset(DIL),
842 DIL->getBaseDiscriminator()),
843 CalleeName, Reader->getRemapper());
844 }
845
846 /// Returns a vector of FunctionSamples that are the indirect call targets
847 /// of \p Inst. The vector is sorted by the total number of samples. Stores
848 /// the total call count of the indirect call in \p Sum.
849 std::vector<const FunctionSamples *>
findIndirectCallFunctionSamples(const Instruction & Inst,uint64_t & Sum) const850 SampleProfileLoader::findIndirectCallFunctionSamples(
851 const Instruction &Inst, uint64_t &Sum) const {
852 const DILocation *DIL = Inst.getDebugLoc();
853 std::vector<const FunctionSamples *> R;
854
855 if (!DIL) {
856 return R;
857 }
858
859 const FunctionSamples *FS = findFunctionSamples(Inst);
860 if (FS == nullptr)
861 return R;
862
863 uint32_t LineOffset = FunctionSamples::getOffset(DIL);
864 uint32_t Discriminator = DIL->getBaseDiscriminator();
865
866 auto T = FS->findCallTargetMapAt(LineOffset, Discriminator);
867 Sum = 0;
868 if (T)
869 for (const auto &T_C : T.get())
870 Sum += T_C.second;
871 if (const FunctionSamplesMap *M = FS->findFunctionSamplesMapAt(LineLocation(
872 FunctionSamples::getOffset(DIL), DIL->getBaseDiscriminator()))) {
873 if (M->empty())
874 return R;
875 for (const auto &NameFS : *M) {
876 Sum += NameFS.second.getEntrySamples();
877 R.push_back(&NameFS.second);
878 }
879 llvm::sort(R, [](const FunctionSamples *L, const FunctionSamples *R) {
880 if (L->getEntrySamples() != R->getEntrySamples())
881 return L->getEntrySamples() > R->getEntrySamples();
882 return FunctionSamples::getGUID(L->getName()) <
883 FunctionSamples::getGUID(R->getName());
884 });
885 }
886 return R;
887 }
888
889 /// Get the FunctionSamples for an instruction.
890 ///
891 /// The FunctionSamples of an instruction \p Inst is the inlined instance
892 /// in which that instruction is coming from. We traverse the inline stack
893 /// of that instruction, and match it with the tree nodes in the profile.
894 ///
895 /// \param Inst Instruction to query.
896 ///
897 /// \returns the FunctionSamples pointer to the inlined instance.
898 const FunctionSamples *
findFunctionSamples(const Instruction & Inst) const899 SampleProfileLoader::findFunctionSamples(const Instruction &Inst) const {
900 const DILocation *DIL = Inst.getDebugLoc();
901 if (!DIL)
902 return Samples;
903
904 auto it = DILocation2SampleMap.try_emplace(DIL,nullptr);
905 if (it.second)
906 it.first->second = Samples->findFunctionSamples(DIL, Reader->getRemapper());
907 return it.first->second;
908 }
909
inlineCallInstruction(CallBase & CB)910 bool SampleProfileLoader::inlineCallInstruction(CallBase &CB) {
911 if (ExternalInlineAdvisor) {
912 auto Advice = ExternalInlineAdvisor->getAdvice(CB);
913 if (!Advice->isInliningRecommended()) {
914 Advice->recordUnattemptedInlining();
915 return false;
916 }
917 // Dummy record, we don't use it for replay.
918 Advice->recordInlining();
919 }
920
921 Function *CalledFunction = CB.getCalledFunction();
922 assert(CalledFunction);
923 DebugLoc DLoc = CB.getDebugLoc();
924 BasicBlock *BB = CB.getParent();
925 InlineParams Params = getInlineParams();
926 Params.ComputeFullInlineCost = true;
927 // Checks if there is anything in the reachable portion of the callee at
928 // this callsite that makes this inlining potentially illegal. Need to
929 // set ComputeFullInlineCost, otherwise getInlineCost may return early
930 // when cost exceeds threshold without checking all IRs in the callee.
931 // The acutal cost does not matter because we only checks isNever() to
932 // see if it is legal to inline the callsite.
933 InlineCost Cost =
934 getInlineCost(CB, Params, GetTTI(*CalledFunction), GetAC, GetTLI);
935 if (Cost.isNever()) {
936 ORE->emit(OptimizationRemarkAnalysis(CSINLINE_DEBUG, "InlineFail", DLoc, BB)
937 << "incompatible inlining");
938 return false;
939 }
940 InlineFunctionInfo IFI(nullptr, GetAC);
941 if (InlineFunction(CB, IFI).isSuccess()) {
942 // The call to InlineFunction erases I, so we can't pass it here.
943 emitInlinedInto(*ORE, DLoc, BB, *CalledFunction, *BB->getParent(), Cost,
944 true, CSINLINE_DEBUG);
945 return true;
946 }
947 return false;
948 }
949
shouldInlineColdCallee(CallBase & CallInst)950 bool SampleProfileLoader::shouldInlineColdCallee(CallBase &CallInst) {
951 if (!ProfileSizeInline)
952 return false;
953
954 Function *Callee = CallInst.getCalledFunction();
955 if (Callee == nullptr)
956 return false;
957
958 InlineCost Cost = getInlineCost(CallInst, getInlineParams(), GetTTI(*Callee),
959 GetAC, GetTLI);
960
961 return Cost.getCost() <= SampleColdCallSiteThreshold;
962 }
963
emitOptimizationRemarksForInlineCandidates(const SmallVectorImpl<CallBase * > & Candidates,const Function & F,bool Hot)964 void SampleProfileLoader::emitOptimizationRemarksForInlineCandidates(
965 const SmallVectorImpl<CallBase *> &Candidates, const Function &F,
966 bool Hot) {
967 for (auto I : Candidates) {
968 Function *CalledFunction = I->getCalledFunction();
969 if (CalledFunction) {
970 ORE->emit(OptimizationRemarkAnalysis(CSINLINE_DEBUG, "InlineAttempt",
971 I->getDebugLoc(), I->getParent())
972 << "previous inlining reattempted for "
973 << (Hot ? "hotness: '" : "size: '")
974 << ore::NV("Callee", CalledFunction) << "' into '"
975 << ore::NV("Caller", &F) << "'");
976 }
977 }
978 }
979
980 /// Iteratively inline hot callsites of a function.
981 ///
982 /// Iteratively traverse all callsites of the function \p F, and find if
983 /// the corresponding inlined instance exists and is hot in profile. If
984 /// it is hot enough, inline the callsites and adds new callsites of the
985 /// callee into the caller. If the call is an indirect call, first promote
986 /// it to direct call. Each indirect call is limited with a single target.
987 ///
988 /// \param F function to perform iterative inlining.
989 /// \param InlinedGUIDs a set to be updated to include all GUIDs that are
990 /// inlined in the profiled binary.
991 ///
992 /// \returns True if there is any inline happened.
inlineHotFunctions(Function & F,DenseSet<GlobalValue::GUID> & InlinedGUIDs)993 bool SampleProfileLoader::inlineHotFunctions(
994 Function &F, DenseSet<GlobalValue::GUID> &InlinedGUIDs) {
995 DenseSet<Instruction *> PromotedInsns;
996
997 // ProfAccForSymsInList is used in callsiteIsHot. The assertion makes sure
998 // Profile symbol list is ignored when profile-sample-accurate is on.
999 assert((!ProfAccForSymsInList ||
1000 (!ProfileSampleAccurate &&
1001 !F.hasFnAttribute("profile-sample-accurate"))) &&
1002 "ProfAccForSymsInList should be false when profile-sample-accurate "
1003 "is enabled");
1004
1005 DenseMap<CallBase *, const FunctionSamples *> localNotInlinedCallSites;
1006 bool Changed = false;
1007 while (true) {
1008 bool LocalChanged = false;
1009 SmallVector<CallBase *, 10> CIS;
1010 for (auto &BB : F) {
1011 bool Hot = false;
1012 SmallVector<CallBase *, 10> AllCandidates;
1013 SmallVector<CallBase *, 10> ColdCandidates;
1014 for (auto &I : BB.getInstList()) {
1015 const FunctionSamples *FS = nullptr;
1016 if (auto *CB = dyn_cast<CallBase>(&I)) {
1017 if (!isa<IntrinsicInst>(I) && (FS = findCalleeFunctionSamples(*CB))) {
1018 assert((!FunctionSamples::UseMD5 || FS->GUIDToFuncNameMap) &&
1019 "GUIDToFuncNameMap has to be populated");
1020 AllCandidates.push_back(CB);
1021 if (FS->getEntrySamples() > 0)
1022 localNotInlinedCallSites.try_emplace(CB, FS);
1023 if (callsiteIsHot(FS, PSI))
1024 Hot = true;
1025 else if (shouldInlineColdCallee(*CB))
1026 ColdCandidates.push_back(CB);
1027 }
1028 }
1029 }
1030 if (Hot || ExternalInlineAdvisor) {
1031 CIS.insert(CIS.begin(), AllCandidates.begin(), AllCandidates.end());
1032 emitOptimizationRemarksForInlineCandidates(AllCandidates, F, true);
1033 } else {
1034 CIS.insert(CIS.begin(), ColdCandidates.begin(), ColdCandidates.end());
1035 emitOptimizationRemarksForInlineCandidates(ColdCandidates, F, false);
1036 }
1037 }
1038 for (CallBase *I : CIS) {
1039 Function *CalledFunction = I->getCalledFunction();
1040 // Do not inline recursive calls.
1041 if (CalledFunction == &F)
1042 continue;
1043 if (I->isIndirectCall()) {
1044 if (PromotedInsns.count(I))
1045 continue;
1046 uint64_t Sum;
1047 for (const auto *FS : findIndirectCallFunctionSamples(*I, Sum)) {
1048 if (IsThinLTOPreLink) {
1049 FS->findInlinedFunctions(InlinedGUIDs, F.getParent(),
1050 PSI->getOrCompHotCountThreshold());
1051 continue;
1052 }
1053 if (!callsiteIsHot(FS, PSI))
1054 continue;
1055
1056 const char *Reason = "Callee function not available";
1057 // R->getValue() != &F is to prevent promoting a recursive call.
1058 // If it is a recursive call, we do not inline it as it could bloat
1059 // the code exponentially. There is way to better handle this, e.g.
1060 // clone the caller first, and inline the cloned caller if it is
1061 // recursive. As llvm does not inline recursive calls, we will
1062 // simply ignore it instead of handling it explicitly.
1063 auto CalleeFunctionName = FS->getFuncName();
1064 auto R = SymbolMap.find(CalleeFunctionName);
1065 if (R != SymbolMap.end() && R->getValue() &&
1066 !R->getValue()->isDeclaration() &&
1067 R->getValue()->getSubprogram() &&
1068 R->getValue()->hasFnAttribute("use-sample-profile") &&
1069 R->getValue() != &F &&
1070 isLegalToPromote(*I, R->getValue(), &Reason)) {
1071 uint64_t C = FS->getEntrySamples();
1072 auto &DI =
1073 pgo::promoteIndirectCall(*I, R->getValue(), C, Sum, false, ORE);
1074 Sum -= C;
1075 PromotedInsns.insert(I);
1076 // If profile mismatches, we should not attempt to inline DI.
1077 if ((isa<CallInst>(DI) || isa<InvokeInst>(DI)) &&
1078 inlineCallInstruction(cast<CallBase>(DI))) {
1079 localNotInlinedCallSites.erase(I);
1080 LocalChanged = true;
1081 ++NumCSInlined;
1082 }
1083 } else {
1084 LLVM_DEBUG(dbgs()
1085 << "\nFailed to promote indirect call to "
1086 << CalleeFunctionName << " because " << Reason << "\n");
1087 }
1088 }
1089 } else if (CalledFunction && CalledFunction->getSubprogram() &&
1090 !CalledFunction->isDeclaration()) {
1091 if (inlineCallInstruction(*I)) {
1092 localNotInlinedCallSites.erase(I);
1093 LocalChanged = true;
1094 ++NumCSInlined;
1095 }
1096 } else if (IsThinLTOPreLink) {
1097 findCalleeFunctionSamples(*I)->findInlinedFunctions(
1098 InlinedGUIDs, F.getParent(), PSI->getOrCompHotCountThreshold());
1099 }
1100 }
1101 if (LocalChanged) {
1102 Changed = true;
1103 } else {
1104 break;
1105 }
1106 }
1107
1108 // Accumulate not inlined callsite information into notInlinedSamples
1109 for (const auto &Pair : localNotInlinedCallSites) {
1110 CallBase *I = Pair.getFirst();
1111 Function *Callee = I->getCalledFunction();
1112 if (!Callee || Callee->isDeclaration())
1113 continue;
1114
1115 ORE->emit(OptimizationRemarkAnalysis(CSINLINE_DEBUG, "NotInline",
1116 I->getDebugLoc(), I->getParent())
1117 << "previous inlining not repeated: '"
1118 << ore::NV("Callee", Callee) << "' into '"
1119 << ore::NV("Caller", &F) << "'");
1120
1121 ++NumCSNotInlined;
1122 const FunctionSamples *FS = Pair.getSecond();
1123 if (FS->getTotalSamples() == 0 && FS->getEntrySamples() == 0) {
1124 continue;
1125 }
1126
1127 if (ProfileMergeInlinee) {
1128 // A function call can be replicated by optimizations like callsite
1129 // splitting or jump threading and the replicates end up sharing the
1130 // sample nested callee profile instead of slicing the original inlinee's
1131 // profile. We want to do merge exactly once by filtering out callee
1132 // profiles with a non-zero head sample count.
1133 if (FS->getHeadSamples() == 0) {
1134 // Use entry samples as head samples during the merge, as inlinees
1135 // don't have head samples.
1136 const_cast<FunctionSamples *>(FS)->addHeadSamples(
1137 FS->getEntrySamples());
1138
1139 // Note that we have to do the merge right after processing function.
1140 // This allows OutlineFS's profile to be used for annotation during
1141 // top-down processing of functions' annotation.
1142 FunctionSamples *OutlineFS = Reader->getOrCreateSamplesFor(*Callee);
1143 OutlineFS->merge(*FS);
1144 }
1145 } else {
1146 auto pair =
1147 notInlinedCallInfo.try_emplace(Callee, NotInlinedProfileInfo{0});
1148 pair.first->second.entryCount += FS->getEntrySamples();
1149 }
1150 }
1151 return Changed;
1152 }
1153
1154 /// Find equivalence classes for the given block.
1155 ///
1156 /// This finds all the blocks that are guaranteed to execute the same
1157 /// number of times as \p BB1. To do this, it traverses all the
1158 /// descendants of \p BB1 in the dominator or post-dominator tree.
1159 ///
1160 /// A block BB2 will be in the same equivalence class as \p BB1 if
1161 /// the following holds:
1162 ///
1163 /// 1- \p BB1 is a descendant of BB2 in the opposite tree. So, if BB2
1164 /// is a descendant of \p BB1 in the dominator tree, then BB2 should
1165 /// dominate BB1 in the post-dominator tree.
1166 ///
1167 /// 2- Both BB2 and \p BB1 must be in the same loop.
1168 ///
1169 /// For every block BB2 that meets those two requirements, we set BB2's
1170 /// equivalence class to \p BB1.
1171 ///
1172 /// \param BB1 Block to check.
1173 /// \param Descendants Descendants of \p BB1 in either the dom or pdom tree.
1174 /// \param DomTree Opposite dominator tree. If \p Descendants is filled
1175 /// with blocks from \p BB1's dominator tree, then
1176 /// this is the post-dominator tree, and vice versa.
1177 template <bool IsPostDom>
findEquivalencesFor(BasicBlock * BB1,ArrayRef<BasicBlock * > Descendants,DominatorTreeBase<BasicBlock,IsPostDom> * DomTree)1178 void SampleProfileLoader::findEquivalencesFor(
1179 BasicBlock *BB1, ArrayRef<BasicBlock *> Descendants,
1180 DominatorTreeBase<BasicBlock, IsPostDom> *DomTree) {
1181 const BasicBlock *EC = EquivalenceClass[BB1];
1182 uint64_t Weight = BlockWeights[EC];
1183 for (const auto *BB2 : Descendants) {
1184 bool IsDomParent = DomTree->dominates(BB2, BB1);
1185 bool IsInSameLoop = LI->getLoopFor(BB1) == LI->getLoopFor(BB2);
1186 if (BB1 != BB2 && IsDomParent && IsInSameLoop) {
1187 EquivalenceClass[BB2] = EC;
1188 // If BB2 is visited, then the entire EC should be marked as visited.
1189 if (VisitedBlocks.count(BB2)) {
1190 VisitedBlocks.insert(EC);
1191 }
1192
1193 // If BB2 is heavier than BB1, make BB2 have the same weight
1194 // as BB1.
1195 //
1196 // Note that we don't worry about the opposite situation here
1197 // (when BB2 is lighter than BB1). We will deal with this
1198 // during the propagation phase. Right now, we just want to
1199 // make sure that BB1 has the largest weight of all the
1200 // members of its equivalence set.
1201 Weight = std::max(Weight, BlockWeights[BB2]);
1202 }
1203 }
1204 if (EC == &EC->getParent()->getEntryBlock()) {
1205 BlockWeights[EC] = Samples->getHeadSamples() + 1;
1206 } else {
1207 BlockWeights[EC] = Weight;
1208 }
1209 }
1210
1211 /// Find equivalence classes.
1212 ///
1213 /// Since samples may be missing from blocks, we can fill in the gaps by setting
1214 /// the weights of all the blocks in the same equivalence class to the same
1215 /// weight. To compute the concept of equivalence, we use dominance and loop
1216 /// information. Two blocks B1 and B2 are in the same equivalence class if B1
1217 /// dominates B2, B2 post-dominates B1 and both are in the same loop.
1218 ///
1219 /// \param F The function to query.
findEquivalenceClasses(Function & F)1220 void SampleProfileLoader::findEquivalenceClasses(Function &F) {
1221 SmallVector<BasicBlock *, 8> DominatedBBs;
1222 LLVM_DEBUG(dbgs() << "\nBlock equivalence classes\n");
1223 // Find equivalence sets based on dominance and post-dominance information.
1224 for (auto &BB : F) {
1225 BasicBlock *BB1 = &BB;
1226
1227 // Compute BB1's equivalence class once.
1228 if (EquivalenceClass.count(BB1)) {
1229 LLVM_DEBUG(printBlockEquivalence(dbgs(), BB1));
1230 continue;
1231 }
1232
1233 // By default, blocks are in their own equivalence class.
1234 EquivalenceClass[BB1] = BB1;
1235
1236 // Traverse all the blocks dominated by BB1. We are looking for
1237 // every basic block BB2 such that:
1238 //
1239 // 1- BB1 dominates BB2.
1240 // 2- BB2 post-dominates BB1.
1241 // 3- BB1 and BB2 are in the same loop nest.
1242 //
1243 // If all those conditions hold, it means that BB2 is executed
1244 // as many times as BB1, so they are placed in the same equivalence
1245 // class by making BB2's equivalence class be BB1.
1246 DominatedBBs.clear();
1247 DT->getDescendants(BB1, DominatedBBs);
1248 findEquivalencesFor(BB1, DominatedBBs, PDT.get());
1249
1250 LLVM_DEBUG(printBlockEquivalence(dbgs(), BB1));
1251 }
1252
1253 // Assign weights to equivalence classes.
1254 //
1255 // All the basic blocks in the same equivalence class will execute
1256 // the same number of times. Since we know that the head block in
1257 // each equivalence class has the largest weight, assign that weight
1258 // to all the blocks in that equivalence class.
1259 LLVM_DEBUG(
1260 dbgs() << "\nAssign the same weight to all blocks in the same class\n");
1261 for (auto &BI : F) {
1262 const BasicBlock *BB = &BI;
1263 const BasicBlock *EquivBB = EquivalenceClass[BB];
1264 if (BB != EquivBB)
1265 BlockWeights[BB] = BlockWeights[EquivBB];
1266 LLVM_DEBUG(printBlockWeight(dbgs(), BB));
1267 }
1268 }
1269
1270 /// Visit the given edge to decide if it has a valid weight.
1271 ///
1272 /// If \p E has not been visited before, we copy to \p UnknownEdge
1273 /// and increment the count of unknown edges.
1274 ///
1275 /// \param E Edge to visit.
1276 /// \param NumUnknownEdges Current number of unknown edges.
1277 /// \param UnknownEdge Set if E has not been visited before.
1278 ///
1279 /// \returns E's weight, if known. Otherwise, return 0.
visitEdge(Edge E,unsigned * NumUnknownEdges,Edge * UnknownEdge)1280 uint64_t SampleProfileLoader::visitEdge(Edge E, unsigned *NumUnknownEdges,
1281 Edge *UnknownEdge) {
1282 if (!VisitedEdges.count(E)) {
1283 (*NumUnknownEdges)++;
1284 *UnknownEdge = E;
1285 return 0;
1286 }
1287
1288 return EdgeWeights[E];
1289 }
1290
1291 /// Propagate weights through incoming/outgoing edges.
1292 ///
1293 /// If the weight of a basic block is known, and there is only one edge
1294 /// with an unknown weight, we can calculate the weight of that edge.
1295 ///
1296 /// Similarly, if all the edges have a known count, we can calculate the
1297 /// count of the basic block, if needed.
1298 ///
1299 /// \param F Function to process.
1300 /// \param UpdateBlockCount Whether we should update basic block counts that
1301 /// has already been annotated.
1302 ///
1303 /// \returns True if new weights were assigned to edges or blocks.
propagateThroughEdges(Function & F,bool UpdateBlockCount)1304 bool SampleProfileLoader::propagateThroughEdges(Function &F,
1305 bool UpdateBlockCount) {
1306 bool Changed = false;
1307 LLVM_DEBUG(dbgs() << "\nPropagation through edges\n");
1308 for (const auto &BI : F) {
1309 const BasicBlock *BB = &BI;
1310 const BasicBlock *EC = EquivalenceClass[BB];
1311
1312 // Visit all the predecessor and successor edges to determine
1313 // which ones have a weight assigned already. Note that it doesn't
1314 // matter that we only keep track of a single unknown edge. The
1315 // only case we are interested in handling is when only a single
1316 // edge is unknown (see setEdgeOrBlockWeight).
1317 for (unsigned i = 0; i < 2; i++) {
1318 uint64_t TotalWeight = 0;
1319 unsigned NumUnknownEdges = 0, NumTotalEdges = 0;
1320 Edge UnknownEdge, SelfReferentialEdge, SingleEdge;
1321
1322 if (i == 0) {
1323 // First, visit all predecessor edges.
1324 NumTotalEdges = Predecessors[BB].size();
1325 for (auto *Pred : Predecessors[BB]) {
1326 Edge E = std::make_pair(Pred, BB);
1327 TotalWeight += visitEdge(E, &NumUnknownEdges, &UnknownEdge);
1328 if (E.first == E.second)
1329 SelfReferentialEdge = E;
1330 }
1331 if (NumTotalEdges == 1) {
1332 SingleEdge = std::make_pair(Predecessors[BB][0], BB);
1333 }
1334 } else {
1335 // On the second round, visit all successor edges.
1336 NumTotalEdges = Successors[BB].size();
1337 for (auto *Succ : Successors[BB]) {
1338 Edge E = std::make_pair(BB, Succ);
1339 TotalWeight += visitEdge(E, &NumUnknownEdges, &UnknownEdge);
1340 }
1341 if (NumTotalEdges == 1) {
1342 SingleEdge = std::make_pair(BB, Successors[BB][0]);
1343 }
1344 }
1345
1346 // After visiting all the edges, there are three cases that we
1347 // can handle immediately:
1348 //
1349 // - All the edge weights are known (i.e., NumUnknownEdges == 0).
1350 // In this case, we simply check that the sum of all the edges
1351 // is the same as BB's weight. If not, we change BB's weight
1352 // to match. Additionally, if BB had not been visited before,
1353 // we mark it visited.
1354 //
1355 // - Only one edge is unknown and BB has already been visited.
1356 // In this case, we can compute the weight of the edge by
1357 // subtracting the total block weight from all the known
1358 // edge weights. If the edges weight more than BB, then the
1359 // edge of the last remaining edge is set to zero.
1360 //
1361 // - There exists a self-referential edge and the weight of BB is
1362 // known. In this case, this edge can be based on BB's weight.
1363 // We add up all the other known edges and set the weight on
1364 // the self-referential edge as we did in the previous case.
1365 //
1366 // In any other case, we must continue iterating. Eventually,
1367 // all edges will get a weight, or iteration will stop when
1368 // it reaches SampleProfileMaxPropagateIterations.
1369 if (NumUnknownEdges <= 1) {
1370 uint64_t &BBWeight = BlockWeights[EC];
1371 if (NumUnknownEdges == 0) {
1372 if (!VisitedBlocks.count(EC)) {
1373 // If we already know the weight of all edges, the weight of the
1374 // basic block can be computed. It should be no larger than the sum
1375 // of all edge weights.
1376 if (TotalWeight > BBWeight) {
1377 BBWeight = TotalWeight;
1378 Changed = true;
1379 LLVM_DEBUG(dbgs() << "All edge weights for " << BB->getName()
1380 << " known. Set weight for block: ";
1381 printBlockWeight(dbgs(), BB););
1382 }
1383 } else if (NumTotalEdges == 1 &&
1384 EdgeWeights[SingleEdge] < BlockWeights[EC]) {
1385 // If there is only one edge for the visited basic block, use the
1386 // block weight to adjust edge weight if edge weight is smaller.
1387 EdgeWeights[SingleEdge] = BlockWeights[EC];
1388 Changed = true;
1389 }
1390 } else if (NumUnknownEdges == 1 && VisitedBlocks.count(EC)) {
1391 // If there is a single unknown edge and the block has been
1392 // visited, then we can compute E's weight.
1393 if (BBWeight >= TotalWeight)
1394 EdgeWeights[UnknownEdge] = BBWeight - TotalWeight;
1395 else
1396 EdgeWeights[UnknownEdge] = 0;
1397 const BasicBlock *OtherEC;
1398 if (i == 0)
1399 OtherEC = EquivalenceClass[UnknownEdge.first];
1400 else
1401 OtherEC = EquivalenceClass[UnknownEdge.second];
1402 // Edge weights should never exceed the BB weights it connects.
1403 if (VisitedBlocks.count(OtherEC) &&
1404 EdgeWeights[UnknownEdge] > BlockWeights[OtherEC])
1405 EdgeWeights[UnknownEdge] = BlockWeights[OtherEC];
1406 VisitedEdges.insert(UnknownEdge);
1407 Changed = true;
1408 LLVM_DEBUG(dbgs() << "Set weight for edge: ";
1409 printEdgeWeight(dbgs(), UnknownEdge));
1410 }
1411 } else if (VisitedBlocks.count(EC) && BlockWeights[EC] == 0) {
1412 // If a block Weights 0, all its in/out edges should weight 0.
1413 if (i == 0) {
1414 for (auto *Pred : Predecessors[BB]) {
1415 Edge E = std::make_pair(Pred, BB);
1416 EdgeWeights[E] = 0;
1417 VisitedEdges.insert(E);
1418 }
1419 } else {
1420 for (auto *Succ : Successors[BB]) {
1421 Edge E = std::make_pair(BB, Succ);
1422 EdgeWeights[E] = 0;
1423 VisitedEdges.insert(E);
1424 }
1425 }
1426 } else if (SelfReferentialEdge.first && VisitedBlocks.count(EC)) {
1427 uint64_t &BBWeight = BlockWeights[BB];
1428 // We have a self-referential edge and the weight of BB is known.
1429 if (BBWeight >= TotalWeight)
1430 EdgeWeights[SelfReferentialEdge] = BBWeight - TotalWeight;
1431 else
1432 EdgeWeights[SelfReferentialEdge] = 0;
1433 VisitedEdges.insert(SelfReferentialEdge);
1434 Changed = true;
1435 LLVM_DEBUG(dbgs() << "Set self-referential edge weight to: ";
1436 printEdgeWeight(dbgs(), SelfReferentialEdge));
1437 }
1438 if (UpdateBlockCount && !VisitedBlocks.count(EC) && TotalWeight > 0) {
1439 BlockWeights[EC] = TotalWeight;
1440 VisitedBlocks.insert(EC);
1441 Changed = true;
1442 }
1443 }
1444 }
1445
1446 return Changed;
1447 }
1448
1449 /// Build in/out edge lists for each basic block in the CFG.
1450 ///
1451 /// We are interested in unique edges. If a block B1 has multiple
1452 /// edges to another block B2, we only add a single B1->B2 edge.
buildEdges(Function & F)1453 void SampleProfileLoader::buildEdges(Function &F) {
1454 for (auto &BI : F) {
1455 BasicBlock *B1 = &BI;
1456
1457 // Add predecessors for B1.
1458 SmallPtrSet<BasicBlock *, 16> Visited;
1459 if (!Predecessors[B1].empty())
1460 llvm_unreachable("Found a stale predecessors list in a basic block.");
1461 for (pred_iterator PI = pred_begin(B1), PE = pred_end(B1); PI != PE; ++PI) {
1462 BasicBlock *B2 = *PI;
1463 if (Visited.insert(B2).second)
1464 Predecessors[B1].push_back(B2);
1465 }
1466
1467 // Add successors for B1.
1468 Visited.clear();
1469 if (!Successors[B1].empty())
1470 llvm_unreachable("Found a stale successors list in a basic block.");
1471 for (succ_iterator SI = succ_begin(B1), SE = succ_end(B1); SI != SE; ++SI) {
1472 BasicBlock *B2 = *SI;
1473 if (Visited.insert(B2).second)
1474 Successors[B1].push_back(B2);
1475 }
1476 }
1477 }
1478
1479 /// Returns the sorted CallTargetMap \p M by count in descending order.
GetSortedValueDataFromCallTargets(const SampleRecord::CallTargetMap & M)1480 static SmallVector<InstrProfValueData, 2> GetSortedValueDataFromCallTargets(
1481 const SampleRecord::CallTargetMap & M) {
1482 SmallVector<InstrProfValueData, 2> R;
1483 for (const auto &I : SampleRecord::SortCallTargets(M)) {
1484 R.emplace_back(InstrProfValueData{FunctionSamples::getGUID(I.first), I.second});
1485 }
1486 return R;
1487 }
1488
1489 /// Propagate weights into edges
1490 ///
1491 /// The following rules are applied to every block BB in the CFG:
1492 ///
1493 /// - If BB has a single predecessor/successor, then the weight
1494 /// of that edge is the weight of the block.
1495 ///
1496 /// - If all incoming or outgoing edges are known except one, and the
1497 /// weight of the block is already known, the weight of the unknown
1498 /// edge will be the weight of the block minus the sum of all the known
1499 /// edges. If the sum of all the known edges is larger than BB's weight,
1500 /// we set the unknown edge weight to zero.
1501 ///
1502 /// - If there is a self-referential edge, and the weight of the block is
1503 /// known, the weight for that edge is set to the weight of the block
1504 /// minus the weight of the other incoming edges to that block (if
1505 /// known).
propagateWeights(Function & F)1506 void SampleProfileLoader::propagateWeights(Function &F) {
1507 bool Changed = true;
1508 unsigned I = 0;
1509
1510 // If BB weight is larger than its corresponding loop's header BB weight,
1511 // use the BB weight to replace the loop header BB weight.
1512 for (auto &BI : F) {
1513 BasicBlock *BB = &BI;
1514 Loop *L = LI->getLoopFor(BB);
1515 if (!L) {
1516 continue;
1517 }
1518 BasicBlock *Header = L->getHeader();
1519 if (Header && BlockWeights[BB] > BlockWeights[Header]) {
1520 BlockWeights[Header] = BlockWeights[BB];
1521 }
1522 }
1523
1524 // Before propagation starts, build, for each block, a list of
1525 // unique predecessors and successors. This is necessary to handle
1526 // identical edges in multiway branches. Since we visit all blocks and all
1527 // edges of the CFG, it is cleaner to build these lists once at the start
1528 // of the pass.
1529 buildEdges(F);
1530
1531 // Propagate until we converge or we go past the iteration limit.
1532 while (Changed && I++ < SampleProfileMaxPropagateIterations) {
1533 Changed = propagateThroughEdges(F, false);
1534 }
1535
1536 // The first propagation propagates BB counts from annotated BBs to unknown
1537 // BBs. The 2nd propagation pass resets edges weights, and use all BB weights
1538 // to propagate edge weights.
1539 VisitedEdges.clear();
1540 Changed = true;
1541 while (Changed && I++ < SampleProfileMaxPropagateIterations) {
1542 Changed = propagateThroughEdges(F, false);
1543 }
1544
1545 // The 3rd propagation pass allows adjust annotated BB weights that are
1546 // obviously wrong.
1547 Changed = true;
1548 while (Changed && I++ < SampleProfileMaxPropagateIterations) {
1549 Changed = propagateThroughEdges(F, true);
1550 }
1551
1552 // Generate MD_prof metadata for every branch instruction using the
1553 // edge weights computed during propagation.
1554 LLVM_DEBUG(dbgs() << "\nPropagation complete. Setting branch weights\n");
1555 LLVMContext &Ctx = F.getContext();
1556 MDBuilder MDB(Ctx);
1557 for (auto &BI : F) {
1558 BasicBlock *BB = &BI;
1559
1560 if (BlockWeights[BB]) {
1561 for (auto &I : BB->getInstList()) {
1562 if (!isa<CallInst>(I) && !isa<InvokeInst>(I))
1563 continue;
1564 if (!cast<CallBase>(I).getCalledFunction()) {
1565 const DebugLoc &DLoc = I.getDebugLoc();
1566 if (!DLoc)
1567 continue;
1568 const DILocation *DIL = DLoc;
1569 uint32_t LineOffset = FunctionSamples::getOffset(DIL);
1570 uint32_t Discriminator = DIL->getBaseDiscriminator();
1571
1572 const FunctionSamples *FS = findFunctionSamples(I);
1573 if (!FS)
1574 continue;
1575 auto T = FS->findCallTargetMapAt(LineOffset, Discriminator);
1576 if (!T || T.get().empty())
1577 continue;
1578 SmallVector<InstrProfValueData, 2> SortedCallTargets =
1579 GetSortedValueDataFromCallTargets(T.get());
1580 uint64_t Sum;
1581 findIndirectCallFunctionSamples(I, Sum);
1582 annotateValueSite(*I.getParent()->getParent()->getParent(), I,
1583 SortedCallTargets, Sum, IPVK_IndirectCallTarget,
1584 SortedCallTargets.size());
1585 } else if (!isa<IntrinsicInst>(&I)) {
1586 I.setMetadata(LLVMContext::MD_prof,
1587 MDB.createBranchWeights(
1588 {static_cast<uint32_t>(BlockWeights[BB])}));
1589 }
1590 }
1591 }
1592 Instruction *TI = BB->getTerminator();
1593 if (TI->getNumSuccessors() == 1)
1594 continue;
1595 if (!isa<BranchInst>(TI) && !isa<SwitchInst>(TI))
1596 continue;
1597
1598 DebugLoc BranchLoc = TI->getDebugLoc();
1599 LLVM_DEBUG(dbgs() << "\nGetting weights for branch at line "
1600 << ((BranchLoc) ? Twine(BranchLoc.getLine())
1601 : Twine("<UNKNOWN LOCATION>"))
1602 << ".\n");
1603 SmallVector<uint32_t, 4> Weights;
1604 uint32_t MaxWeight = 0;
1605 Instruction *MaxDestInst;
1606 for (unsigned I = 0; I < TI->getNumSuccessors(); ++I) {
1607 BasicBlock *Succ = TI->getSuccessor(I);
1608 Edge E = std::make_pair(BB, Succ);
1609 uint64_t Weight = EdgeWeights[E];
1610 LLVM_DEBUG(dbgs() << "\t"; printEdgeWeight(dbgs(), E));
1611 // Use uint32_t saturated arithmetic to adjust the incoming weights,
1612 // if needed. Sample counts in profiles are 64-bit unsigned values,
1613 // but internally branch weights are expressed as 32-bit values.
1614 if (Weight > std::numeric_limits<uint32_t>::max()) {
1615 LLVM_DEBUG(dbgs() << " (saturated due to uint32_t overflow)");
1616 Weight = std::numeric_limits<uint32_t>::max();
1617 }
1618 // Weight is added by one to avoid propagation errors introduced by
1619 // 0 weights.
1620 Weights.push_back(static_cast<uint32_t>(Weight + 1));
1621 if (Weight != 0) {
1622 if (Weight > MaxWeight) {
1623 MaxWeight = Weight;
1624 MaxDestInst = Succ->getFirstNonPHIOrDbgOrLifetime();
1625 }
1626 }
1627 }
1628
1629 misexpect::verifyMisExpect(TI, Weights, TI->getContext());
1630
1631 uint64_t TempWeight;
1632 // Only set weights if there is at least one non-zero weight.
1633 // In any other case, let the analyzer set weights.
1634 // Do not set weights if the weights are present. In ThinLTO, the profile
1635 // annotation is done twice. If the first annotation already set the
1636 // weights, the second pass does not need to set it.
1637 if (MaxWeight > 0 && !TI->extractProfTotalWeight(TempWeight)) {
1638 LLVM_DEBUG(dbgs() << "SUCCESS. Found non-zero weights.\n");
1639 TI->setMetadata(LLVMContext::MD_prof,
1640 MDB.createBranchWeights(Weights));
1641 ORE->emit([&]() {
1642 return OptimizationRemark(DEBUG_TYPE, "PopularDest", MaxDestInst)
1643 << "most popular destination for conditional branches at "
1644 << ore::NV("CondBranchesLoc", BranchLoc);
1645 });
1646 } else {
1647 LLVM_DEBUG(dbgs() << "SKIPPED. All branch weights are zero.\n");
1648 }
1649 }
1650 }
1651
1652 /// Get the line number for the function header.
1653 ///
1654 /// This looks up function \p F in the current compilation unit and
1655 /// retrieves the line number where the function is defined. This is
1656 /// line 0 for all the samples read from the profile file. Every line
1657 /// number is relative to this line.
1658 ///
1659 /// \param F Function object to query.
1660 ///
1661 /// \returns the line number where \p F is defined. If it returns 0,
1662 /// it means that there is no debug information available for \p F.
getFunctionLoc(Function & F)1663 unsigned SampleProfileLoader::getFunctionLoc(Function &F) {
1664 if (DISubprogram *S = F.getSubprogram())
1665 return S->getLine();
1666
1667 if (NoWarnSampleUnused)
1668 return 0;
1669
1670 // If the start of \p F is missing, emit a diagnostic to inform the user
1671 // about the missed opportunity.
1672 F.getContext().diagnose(DiagnosticInfoSampleProfile(
1673 "No debug information found in function " + F.getName() +
1674 ": Function profile not used",
1675 DS_Warning));
1676 return 0;
1677 }
1678
computeDominanceAndLoopInfo(Function & F)1679 void SampleProfileLoader::computeDominanceAndLoopInfo(Function &F) {
1680 DT.reset(new DominatorTree);
1681 DT->recalculate(F);
1682
1683 PDT.reset(new PostDominatorTree(F));
1684
1685 LI.reset(new LoopInfo);
1686 LI->analyze(*DT);
1687 }
1688
1689 /// Generate branch weight metadata for all branches in \p F.
1690 ///
1691 /// Branch weights are computed out of instruction samples using a
1692 /// propagation heuristic. Propagation proceeds in 3 phases:
1693 ///
1694 /// 1- Assignment of block weights. All the basic blocks in the function
1695 /// are initial assigned the same weight as their most frequently
1696 /// executed instruction.
1697 ///
1698 /// 2- Creation of equivalence classes. Since samples may be missing from
1699 /// blocks, we can fill in the gaps by setting the weights of all the
1700 /// blocks in the same equivalence class to the same weight. To compute
1701 /// the concept of equivalence, we use dominance and loop information.
1702 /// Two blocks B1 and B2 are in the same equivalence class if B1
1703 /// dominates B2, B2 post-dominates B1 and both are in the same loop.
1704 ///
1705 /// 3- Propagation of block weights into edges. This uses a simple
1706 /// propagation heuristic. The following rules are applied to every
1707 /// block BB in the CFG:
1708 ///
1709 /// - If BB has a single predecessor/successor, then the weight
1710 /// of that edge is the weight of the block.
1711 ///
1712 /// - If all the edges are known except one, and the weight of the
1713 /// block is already known, the weight of the unknown edge will
1714 /// be the weight of the block minus the sum of all the known
1715 /// edges. If the sum of all the known edges is larger than BB's weight,
1716 /// we set the unknown edge weight to zero.
1717 ///
1718 /// - If there is a self-referential edge, and the weight of the block is
1719 /// known, the weight for that edge is set to the weight of the block
1720 /// minus the weight of the other incoming edges to that block (if
1721 /// known).
1722 ///
1723 /// Since this propagation is not guaranteed to finalize for every CFG, we
1724 /// only allow it to proceed for a limited number of iterations (controlled
1725 /// by -sample-profile-max-propagate-iterations).
1726 ///
1727 /// FIXME: Try to replace this propagation heuristic with a scheme
1728 /// that is guaranteed to finalize. A work-list approach similar to
1729 /// the standard value propagation algorithm used by SSA-CCP might
1730 /// work here.
1731 ///
1732 /// Once all the branch weights are computed, we emit the MD_prof
1733 /// metadata on BB using the computed values for each of its branches.
1734 ///
1735 /// \param F The function to query.
1736 ///
1737 /// \returns true if \p F was modified. Returns false, otherwise.
emitAnnotations(Function & F)1738 bool SampleProfileLoader::emitAnnotations(Function &F) {
1739 bool Changed = false;
1740
1741 if (getFunctionLoc(F) == 0)
1742 return false;
1743
1744 LLVM_DEBUG(dbgs() << "Line number for the first instruction in "
1745 << F.getName() << ": " << getFunctionLoc(F) << "\n");
1746
1747 DenseSet<GlobalValue::GUID> InlinedGUIDs;
1748 Changed |= inlineHotFunctions(F, InlinedGUIDs);
1749
1750 // Compute basic block weights.
1751 Changed |= computeBlockWeights(F);
1752
1753 if (Changed) {
1754 // Add an entry count to the function using the samples gathered at the
1755 // function entry.
1756 // Sets the GUIDs that are inlined in the profiled binary. This is used
1757 // for ThinLink to make correct liveness analysis, and also make the IR
1758 // match the profiled binary before annotation.
1759 F.setEntryCount(
1760 ProfileCount(Samples->getHeadSamples() + 1, Function::PCT_Real),
1761 &InlinedGUIDs);
1762
1763 // Compute dominance and loop info needed for propagation.
1764 computeDominanceAndLoopInfo(F);
1765
1766 // Find equivalence classes.
1767 findEquivalenceClasses(F);
1768
1769 // Propagate weights to all edges.
1770 propagateWeights(F);
1771 }
1772
1773 // If coverage checking was requested, compute it now.
1774 if (SampleProfileRecordCoverage) {
1775 unsigned Used = CoverageTracker.countUsedRecords(Samples, PSI);
1776 unsigned Total = CoverageTracker.countBodyRecords(Samples, PSI);
1777 unsigned Coverage = CoverageTracker.computeCoverage(Used, Total);
1778 if (Coverage < SampleProfileRecordCoverage) {
1779 F.getContext().diagnose(DiagnosticInfoSampleProfile(
1780 F.getSubprogram()->getFilename(), getFunctionLoc(F),
1781 Twine(Used) + " of " + Twine(Total) + " available profile records (" +
1782 Twine(Coverage) + "%) were applied",
1783 DS_Warning));
1784 }
1785 }
1786
1787 if (SampleProfileSampleCoverage) {
1788 uint64_t Used = CoverageTracker.getTotalUsedSamples();
1789 uint64_t Total = CoverageTracker.countBodySamples(Samples, PSI);
1790 unsigned Coverage = CoverageTracker.computeCoverage(Used, Total);
1791 if (Coverage < SampleProfileSampleCoverage) {
1792 F.getContext().diagnose(DiagnosticInfoSampleProfile(
1793 F.getSubprogram()->getFilename(), getFunctionLoc(F),
1794 Twine(Used) + " of " + Twine(Total) + " available profile samples (" +
1795 Twine(Coverage) + "%) were applied",
1796 DS_Warning));
1797 }
1798 }
1799 return Changed;
1800 }
1801
1802 char SampleProfileLoaderLegacyPass::ID = 0;
1803
1804 INITIALIZE_PASS_BEGIN(SampleProfileLoaderLegacyPass, "sample-profile",
1805 "Sample Profile loader", false, false)
INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)1806 INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
1807 INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)
1808 INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
1809 INITIALIZE_PASS_DEPENDENCY(ProfileSummaryInfoWrapperPass)
1810 INITIALIZE_PASS_END(SampleProfileLoaderLegacyPass, "sample-profile",
1811 "Sample Profile loader", false, false)
1812
1813 std::vector<Function *>
1814 SampleProfileLoader::buildFunctionOrder(Module &M, CallGraph *CG) {
1815 std::vector<Function *> FunctionOrderList;
1816 FunctionOrderList.reserve(M.size());
1817
1818 if (!ProfileTopDownLoad || CG == nullptr) {
1819 if (ProfileMergeInlinee) {
1820 // Disable ProfileMergeInlinee if profile is not loaded in top down order,
1821 // because the profile for a function may be used for the profile
1822 // annotation of its outline copy before the profile merging of its
1823 // non-inlined inline instances, and that is not the way how
1824 // ProfileMergeInlinee is supposed to work.
1825 ProfileMergeInlinee = false;
1826 }
1827
1828 for (Function &F : M)
1829 if (!F.isDeclaration() && F.hasFnAttribute("use-sample-profile"))
1830 FunctionOrderList.push_back(&F);
1831 return FunctionOrderList;
1832 }
1833
1834 assert(&CG->getModule() == &M);
1835 scc_iterator<CallGraph *> CGI = scc_begin(CG);
1836 while (!CGI.isAtEnd()) {
1837 for (CallGraphNode *node : *CGI) {
1838 auto F = node->getFunction();
1839 if (F && !F->isDeclaration() && F->hasFnAttribute("use-sample-profile"))
1840 FunctionOrderList.push_back(F);
1841 }
1842 ++CGI;
1843 }
1844
1845 std::reverse(FunctionOrderList.begin(), FunctionOrderList.end());
1846 return FunctionOrderList;
1847 }
1848
doInitialization(Module & M,FunctionAnalysisManager * FAM)1849 bool SampleProfileLoader::doInitialization(Module &M,
1850 FunctionAnalysisManager *FAM) {
1851 auto &Ctx = M.getContext();
1852
1853 auto ReaderOrErr =
1854 SampleProfileReader::create(Filename, Ctx, RemappingFilename);
1855 if (std::error_code EC = ReaderOrErr.getError()) {
1856 std::string Msg = "Could not open profile: " + EC.message();
1857 Ctx.diagnose(DiagnosticInfoSampleProfile(Filename, Msg));
1858 return false;
1859 }
1860 Reader = std::move(ReaderOrErr.get());
1861 Reader->collectFuncsFrom(M);
1862 ProfileIsValid = (Reader->read() == sampleprof_error::success);
1863 PSL = Reader->getProfileSymbolList();
1864
1865 // While profile-sample-accurate is on, ignore symbol list.
1866 ProfAccForSymsInList =
1867 ProfileAccurateForSymsInList && PSL && !ProfileSampleAccurate;
1868 if (ProfAccForSymsInList) {
1869 NamesInProfile.clear();
1870 if (auto NameTable = Reader->getNameTable())
1871 NamesInProfile.insert(NameTable->begin(), NameTable->end());
1872 }
1873
1874 if (FAM && !ProfileInlineReplayFile.empty()) {
1875 ExternalInlineAdvisor = std::make_unique<ReplayInlineAdvisor>(
1876 *FAM, Ctx, ProfileInlineReplayFile);
1877 if (!ExternalInlineAdvisor->areReplayRemarksLoaded())
1878 ExternalInlineAdvisor.reset();
1879 }
1880
1881 return true;
1882 }
1883
createSampleProfileLoaderPass()1884 ModulePass *llvm::createSampleProfileLoaderPass() {
1885 return new SampleProfileLoaderLegacyPass();
1886 }
1887
createSampleProfileLoaderPass(StringRef Name)1888 ModulePass *llvm::createSampleProfileLoaderPass(StringRef Name) {
1889 return new SampleProfileLoaderLegacyPass(Name);
1890 }
1891
runOnModule(Module & M,ModuleAnalysisManager * AM,ProfileSummaryInfo * _PSI,CallGraph * CG)1892 bool SampleProfileLoader::runOnModule(Module &M, ModuleAnalysisManager *AM,
1893 ProfileSummaryInfo *_PSI, CallGraph *CG) {
1894 if (!ProfileIsValid)
1895 return false;
1896 GUIDToFuncNameMapper Mapper(M, *Reader, GUIDToFuncNameMap);
1897
1898 PSI = _PSI;
1899 if (M.getProfileSummary(/* IsCS */ false) == nullptr) {
1900 M.setProfileSummary(Reader->getSummary().getMD(M.getContext()),
1901 ProfileSummary::PSK_Sample);
1902 PSI->refresh();
1903 }
1904 // Compute the total number of samples collected in this profile.
1905 for (const auto &I : Reader->getProfiles())
1906 TotalCollectedSamples += I.second.getTotalSamples();
1907
1908 auto Remapper = Reader->getRemapper();
1909 // Populate the symbol map.
1910 for (const auto &N_F : M.getValueSymbolTable()) {
1911 StringRef OrigName = N_F.getKey();
1912 Function *F = dyn_cast<Function>(N_F.getValue());
1913 if (F == nullptr)
1914 continue;
1915 SymbolMap[OrigName] = F;
1916 auto pos = OrigName.find('.');
1917 if (pos != StringRef::npos) {
1918 StringRef NewName = OrigName.substr(0, pos);
1919 auto r = SymbolMap.insert(std::make_pair(NewName, F));
1920 // Failiing to insert means there is already an entry in SymbolMap,
1921 // thus there are multiple functions that are mapped to the same
1922 // stripped name. In this case of name conflicting, set the value
1923 // to nullptr to avoid confusion.
1924 if (!r.second)
1925 r.first->second = nullptr;
1926 OrigName = NewName;
1927 }
1928 // Insert the remapped names into SymbolMap.
1929 if (Remapper) {
1930 if (auto MapName = Remapper->lookUpNameInProfile(OrigName)) {
1931 if (*MapName == OrigName)
1932 continue;
1933 SymbolMap.insert(std::make_pair(*MapName, F));
1934 }
1935 }
1936 }
1937
1938 bool retval = false;
1939 for (auto F : buildFunctionOrder(M, CG)) {
1940 assert(!F->isDeclaration());
1941 clearFunctionData();
1942 retval |= runOnFunction(*F, AM);
1943 }
1944
1945 // Account for cold calls not inlined....
1946 for (const std::pair<Function *, NotInlinedProfileInfo> &pair :
1947 notInlinedCallInfo)
1948 updateProfileCallee(pair.first, pair.second.entryCount);
1949
1950 return retval;
1951 }
1952
runOnModule(Module & M)1953 bool SampleProfileLoaderLegacyPass::runOnModule(Module &M) {
1954 ACT = &getAnalysis<AssumptionCacheTracker>();
1955 TTIWP = &getAnalysis<TargetTransformInfoWrapperPass>();
1956 TLIWP = &getAnalysis<TargetLibraryInfoWrapperPass>();
1957 ProfileSummaryInfo *PSI =
1958 &getAnalysis<ProfileSummaryInfoWrapperPass>().getPSI();
1959 return SampleLoader.runOnModule(M, nullptr, PSI, nullptr);
1960 }
1961
runOnFunction(Function & F,ModuleAnalysisManager * AM)1962 bool SampleProfileLoader::runOnFunction(Function &F, ModuleAnalysisManager *AM) {
1963
1964 DILocation2SampleMap.clear();
1965 // By default the entry count is initialized to -1, which will be treated
1966 // conservatively by getEntryCount as the same as unknown (None). This is
1967 // to avoid newly added code to be treated as cold. If we have samples
1968 // this will be overwritten in emitAnnotations.
1969 uint64_t initialEntryCount = -1;
1970
1971 ProfAccForSymsInList = ProfileAccurateForSymsInList && PSL;
1972 if (ProfileSampleAccurate || F.hasFnAttribute("profile-sample-accurate")) {
1973 // initialize all the function entry counts to 0. It means all the
1974 // functions without profile will be regarded as cold.
1975 initialEntryCount = 0;
1976 // profile-sample-accurate is a user assertion which has a higher precedence
1977 // than symbol list. When profile-sample-accurate is on, ignore symbol list.
1978 ProfAccForSymsInList = false;
1979 }
1980
1981 // PSL -- profile symbol list include all the symbols in sampled binary.
1982 // If ProfileAccurateForSymsInList is enabled, PSL is used to treat
1983 // old functions without samples being cold, without having to worry
1984 // about new and hot functions being mistakenly treated as cold.
1985 if (ProfAccForSymsInList) {
1986 // Initialize the entry count to 0 for functions in the list.
1987 if (PSL->contains(F.getName()))
1988 initialEntryCount = 0;
1989
1990 // Function in the symbol list but without sample will be regarded as
1991 // cold. To minimize the potential negative performance impact it could
1992 // have, we want to be a little conservative here saying if a function
1993 // shows up in the profile, no matter as outline function, inline instance
1994 // or call targets, treat the function as not being cold. This will handle
1995 // the cases such as most callsites of a function are inlined in sampled
1996 // binary but not inlined in current build (because of source code drift,
1997 // imprecise debug information, or the callsites are all cold individually
1998 // but not cold accumulatively...), so the outline function showing up as
1999 // cold in sampled binary will actually not be cold after current build.
2000 StringRef CanonName = FunctionSamples::getCanonicalFnName(F);
2001 if (NamesInProfile.count(CanonName))
2002 initialEntryCount = -1;
2003 }
2004
2005 F.setEntryCount(ProfileCount(initialEntryCount, Function::PCT_Real));
2006 std::unique_ptr<OptimizationRemarkEmitter> OwnedORE;
2007 if (AM) {
2008 auto &FAM =
2009 AM->getResult<FunctionAnalysisManagerModuleProxy>(*F.getParent())
2010 .getManager();
2011 ORE = &FAM.getResult<OptimizationRemarkEmitterAnalysis>(F);
2012 } else {
2013 OwnedORE = std::make_unique<OptimizationRemarkEmitter>(&F);
2014 ORE = OwnedORE.get();
2015 }
2016 Samples = Reader->getSamplesFor(F);
2017 if (Samples && !Samples->empty())
2018 return emitAnnotations(F);
2019 return false;
2020 }
2021
run(Module & M,ModuleAnalysisManager & AM)2022 PreservedAnalyses SampleProfileLoaderPass::run(Module &M,
2023 ModuleAnalysisManager &AM) {
2024 FunctionAnalysisManager &FAM =
2025 AM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
2026
2027 auto GetAssumptionCache = [&](Function &F) -> AssumptionCache & {
2028 return FAM.getResult<AssumptionAnalysis>(F);
2029 };
2030 auto GetTTI = [&](Function &F) -> TargetTransformInfo & {
2031 return FAM.getResult<TargetIRAnalysis>(F);
2032 };
2033 auto GetTLI = [&](Function &F) -> const TargetLibraryInfo & {
2034 return FAM.getResult<TargetLibraryAnalysis>(F);
2035 };
2036
2037 SampleProfileLoader SampleLoader(
2038 ProfileFileName.empty() ? SampleProfileFile : ProfileFileName,
2039 ProfileRemappingFileName.empty() ? SampleProfileRemappingFile
2040 : ProfileRemappingFileName,
2041 IsThinLTOPreLink, GetAssumptionCache, GetTTI, GetTLI);
2042
2043 if (!SampleLoader.doInitialization(M, &FAM))
2044 return PreservedAnalyses::all();
2045
2046 ProfileSummaryInfo *PSI = &AM.getResult<ProfileSummaryAnalysis>(M);
2047 CallGraph &CG = AM.getResult<CallGraphAnalysis>(M);
2048 if (!SampleLoader.runOnModule(M, &AM, PSI, &CG))
2049 return PreservedAnalyses::all();
2050
2051 return PreservedAnalyses::none();
2052 }
2053