1 //===- ProfileSummaryInfo.cpp - Global profile summary information --------===//
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
7 //===----------------------------------------------------------------------===//
9 // This file contains a pass that provides access to the global profile summary
12 //===----------------------------------------------------------------------===//
14 #include "llvm/Analysis/ProfileSummaryInfo.h"
15 #include "llvm/Analysis/BlockFrequencyInfo.h"
16 #include "llvm/IR/BasicBlock.h"
17 #include "llvm/IR/CallSite.h"
18 #include "llvm/IR/Metadata.h"
19 #include "llvm/IR/Module.h"
20 #include "llvm/IR/ProfileSummary.h"
23 // The following two parameters determine the threshold for a count to be
24 // considered hot/cold. These two parameters are percentile values (multiplied
25 // by 10000). If the counts are sorted in descending order, the minimum count to
26 // reach ProfileSummaryCutoffHot gives the threshold to determine a hot count.
27 // Similarly, the minimum count to reach ProfileSummaryCutoffCold gives the
28 // threshold for determining cold count (everything <= this threshold is
31 static cl::opt<int> ProfileSummaryCutoffHot(
32 "profile-summary-cutoff-hot", cl::Hidden, cl::init(990000), cl::ZeroOrMore,
33 cl::desc("A count is hot if it exceeds the minimum count to"
34 " reach this percentile of total counts."));
36 static cl::opt<int> ProfileSummaryCutoffCold(
37 "profile-summary-cutoff-cold", cl::Hidden, cl::init(999999), cl::ZeroOrMore,
38 cl::desc("A count is cold if it is below the minimum count"
39 " to reach this percentile of total counts."));
41 static cl::opt<unsigned> ProfileSummaryHugeWorkingSetSizeThreshold(
42 "profile-summary-huge-working-set-size-threshold", cl::Hidden,
43 cl::init(15000), cl::ZeroOrMore,
44 cl::desc("The code working set size is considered huge if the number of"
45 " blocks required to reach the -profile-summary-cutoff-hot"
46 " percentile exceeds this count."));
48 // The next two options override the counts derived from summary computation and
49 // are useful for debugging purposes.
50 static cl::opt<int> ProfileSummaryHotCount(
51 "profile-summary-hot-count", cl::ReallyHidden, cl::ZeroOrMore,
52 cl::desc("A fixed hot count that overrides the count derived from"
53 " profile-summary-cutoff-hot"));
55 static cl::opt<int> ProfileSummaryColdCount(
56 "profile-summary-cold-count", cl::ReallyHidden, cl::ZeroOrMore,
57 cl::desc("A fixed cold count that overrides the count derived from"
58 " profile-summary-cutoff-cold"));
60 // Find the summary entry for a desired percentile of counts.
61 static const ProfileSummaryEntry &getEntryForPercentile(SummaryEntryVector &DS,
62 uint64_t Percentile) {
63 auto It = llvm::bsearch(DS, [=](const ProfileSummaryEntry &Entry) {
64 return Percentile <= Entry.Cutoff;
66 // The required percentile has to be <= one of the percentiles in the
69 report_fatal_error("Desired percentile exceeds the maximum cutoff");
73 // The profile summary metadata may be attached either by the frontend or by
74 // any backend passes (IR level instrumentation, for example). This method
75 // checks if the Summary is null and if so checks if the summary metadata is now
76 // available in the module and parses it to get the Summary object. Returns true
77 // if a valid Summary is available.
78 bool ProfileSummaryInfo::computeSummary() {
81 // First try to get context sensitive ProfileSummary.
82 auto *SummaryMD = M.getProfileSummary(/* IsCS */ true);
84 Summary.reset(ProfileSummary::getFromMD(SummaryMD));
87 // This will actually return PSK_Instr or PSK_Sample summary.
88 SummaryMD = M.getProfileSummary(/* IsCS */ false);
91 Summary.reset(ProfileSummary::getFromMD(SummaryMD));
96 ProfileSummaryInfo::getProfileCount(const Instruction *Inst,
97 BlockFrequencyInfo *BFI,
98 bool AllowSynthetic) {
101 assert((isa<CallInst>(Inst) || isa<InvokeInst>(Inst)) &&
102 "We can only get profile count for call/invoke instruction.");
103 if (hasSampleProfile()) {
104 // In sample PGO mode, check if there is a profile metadata on the
105 // instruction. If it is present, determine hotness solely based on that,
106 // since the sampled entry count may not be accurate. If there is no
107 // annotated on the instruction, return None.
109 if (Inst->extractProfTotalWeight(TotalCount))
114 return BFI->getBlockProfileCount(Inst->getParent(), AllowSynthetic);
118 /// Returns true if the function's entry is hot. If it returns false, it
119 /// either means it is not hot or it is unknown whether it is hot or not (for
120 /// example, no profile data is available).
121 bool ProfileSummaryInfo::isFunctionEntryHot(const Function *F) {
122 if (!F || !computeSummary())
124 auto FunctionCount = F->getEntryCount();
125 // FIXME: The heuristic used below for determining hotness is based on
126 // preliminary SPEC tuning for inliner. This will eventually be a
127 // convenience method that calls isHotCount.
128 return FunctionCount && isHotCount(FunctionCount.getCount());
131 /// Returns true if the function contains hot code. This can include a hot
132 /// function entry count, hot basic block, or (in the case of Sample PGO)
133 /// hot total call edge count.
134 /// If it returns false, it either means it is not hot or it is unknown
135 /// (for example, no profile data is available).
136 bool ProfileSummaryInfo::isFunctionHotInCallGraph(const Function *F,
137 BlockFrequencyInfo &BFI) {
138 if (!F || !computeSummary())
140 if (auto FunctionCount = F->getEntryCount())
141 if (isHotCount(FunctionCount.getCount()))
144 if (hasSampleProfile()) {
145 uint64_t TotalCallCount = 0;
146 for (const auto &BB : *F)
147 for (const auto &I : BB)
148 if (isa<CallInst>(I) || isa<InvokeInst>(I))
149 if (auto CallCount = getProfileCount(&I, nullptr))
150 TotalCallCount += CallCount.getValue();
151 if (isHotCount(TotalCallCount))
154 for (const auto &BB : *F)
155 if (isHotBlock(&BB, &BFI))
160 /// Returns true if the function only contains cold code. This means that
161 /// the function entry and blocks are all cold, and (in the case of Sample PGO)
162 /// the total call edge count is cold.
163 /// If it returns false, it either means it is not cold or it is unknown
164 /// (for example, no profile data is available).
165 bool ProfileSummaryInfo::isFunctionColdInCallGraph(const Function *F,
166 BlockFrequencyInfo &BFI) {
167 if (!F || !computeSummary())
169 if (auto FunctionCount = F->getEntryCount())
170 if (!isColdCount(FunctionCount.getCount()))
173 if (hasSampleProfile()) {
174 uint64_t TotalCallCount = 0;
175 for (const auto &BB : *F)
176 for (const auto &I : BB)
177 if (isa<CallInst>(I) || isa<InvokeInst>(I))
178 if (auto CallCount = getProfileCount(&I, nullptr))
179 TotalCallCount += CallCount.getValue();
180 if (!isColdCount(TotalCallCount))
183 for (const auto &BB : *F)
184 if (!isColdBlock(&BB, &BFI))
189 /// Returns true if the function's entry is a cold. If it returns false, it
190 /// either means it is not cold or it is unknown whether it is cold or not (for
191 /// example, no profile data is available).
192 bool ProfileSummaryInfo::isFunctionEntryCold(const Function *F) {
195 if (F->hasFnAttribute(Attribute::Cold))
197 if (!computeSummary())
199 auto FunctionCount = F->getEntryCount();
200 // FIXME: The heuristic used below for determining coldness is based on
201 // preliminary SPEC tuning for inliner. This will eventually be a
202 // convenience method that calls isHotCount.
203 return FunctionCount && isColdCount(FunctionCount.getCount());
206 /// Compute the hot and cold thresholds.
207 void ProfileSummaryInfo::computeThresholds() {
208 if (!computeSummary())
210 auto &DetailedSummary = Summary->getDetailedSummary();
212 getEntryForPercentile(DetailedSummary, ProfileSummaryCutoffHot);
213 HotCountThreshold = HotEntry.MinCount;
214 if (ProfileSummaryHotCount.getNumOccurrences() > 0)
215 HotCountThreshold = ProfileSummaryHotCount;
217 getEntryForPercentile(DetailedSummary, ProfileSummaryCutoffCold);
218 ColdCountThreshold = ColdEntry.MinCount;
219 if (ProfileSummaryColdCount.getNumOccurrences() > 0)
220 ColdCountThreshold = ProfileSummaryColdCount;
221 assert(ColdCountThreshold <= HotCountThreshold &&
222 "Cold count threshold cannot exceed hot count threshold!");
223 HasHugeWorkingSetSize =
224 HotEntry.NumCounts > ProfileSummaryHugeWorkingSetSizeThreshold;
227 bool ProfileSummaryInfo::hasHugeWorkingSetSize() {
228 if (!HasHugeWorkingSetSize)
230 return HasHugeWorkingSetSize && HasHugeWorkingSetSize.getValue();
233 bool ProfileSummaryInfo::isHotCount(uint64_t C) {
234 if (!HotCountThreshold)
236 return HotCountThreshold && C >= HotCountThreshold.getValue();
239 bool ProfileSummaryInfo::isColdCount(uint64_t C) {
240 if (!ColdCountThreshold)
242 return ColdCountThreshold && C <= ColdCountThreshold.getValue();
245 uint64_t ProfileSummaryInfo::getOrCompHotCountThreshold() {
246 if (!HotCountThreshold)
248 return HotCountThreshold ? HotCountThreshold.getValue() : UINT64_MAX;
251 uint64_t ProfileSummaryInfo::getOrCompColdCountThreshold() {
252 if (!ColdCountThreshold)
254 return ColdCountThreshold ? ColdCountThreshold.getValue() : 0;
257 bool ProfileSummaryInfo::isHotBlock(const BasicBlock *BB, BlockFrequencyInfo *BFI) {
258 auto Count = BFI->getBlockProfileCount(BB);
259 return Count && isHotCount(*Count);
262 bool ProfileSummaryInfo::isColdBlock(const BasicBlock *BB,
263 BlockFrequencyInfo *BFI) {
264 auto Count = BFI->getBlockProfileCount(BB);
265 return Count && isColdCount(*Count);
268 bool ProfileSummaryInfo::isHotCallSite(const CallSite &CS,
269 BlockFrequencyInfo *BFI) {
270 auto C = getProfileCount(CS.getInstruction(), BFI);
271 return C && isHotCount(*C);
274 bool ProfileSummaryInfo::isColdCallSite(const CallSite &CS,
275 BlockFrequencyInfo *BFI) {
276 auto C = getProfileCount(CS.getInstruction(), BFI);
278 return isColdCount(*C);
280 // In SamplePGO, if the caller has been sampled, and there is no profile
281 // annotated on the callsite, we consider the callsite as cold.
282 return hasSampleProfile() && CS.getCaller()->hasProfileData();
285 INITIALIZE_PASS(ProfileSummaryInfoWrapperPass, "profile-summary-info",
286 "Profile summary info", false, true)
288 ProfileSummaryInfoWrapperPass::ProfileSummaryInfoWrapperPass()
289 : ImmutablePass(ID) {
290 initializeProfileSummaryInfoWrapperPassPass(*PassRegistry::getPassRegistry());
293 bool ProfileSummaryInfoWrapperPass::doInitialization(Module &M) {
294 PSI.reset(new ProfileSummaryInfo(M));
298 bool ProfileSummaryInfoWrapperPass::doFinalization(Module &M) {
303 AnalysisKey ProfileSummaryAnalysis::Key;
304 ProfileSummaryInfo ProfileSummaryAnalysis::run(Module &M,
305 ModuleAnalysisManager &) {
306 return ProfileSummaryInfo(M);
309 PreservedAnalyses ProfileSummaryPrinterPass::run(Module &M,
310 ModuleAnalysisManager &AM) {
311 ProfileSummaryInfo &PSI = AM.getResult<ProfileSummaryAnalysis>(M);
313 OS << "Functions in " << M.getName() << " with hot/cold annotations: \n";
316 if (PSI.isFunctionEntryHot(&F))
317 OS << " :hot entry ";
318 else if (PSI.isFunctionEntryCold(&F))
319 OS << " :cold entry ";
322 return PreservedAnalyses::all();
325 char ProfileSummaryInfoWrapperPass::ID = 0;