1//===- ProfileSummaryInfo.cpp - Global profile summary information --------===//
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 contains a pass that provides access to the global profile summary
10// information.
11//
12//===----------------------------------------------------------------------===//
13
14#include "llvm/Analysis/ProfileSummaryInfo.h"
15#include "llvm/Analysis/BlockFrequencyInfo.h"
16#include "llvm/IR/BasicBlock.h"
17#include "llvm/IR/Instructions.h"
18#include "llvm/IR/Module.h"
19#include "llvm/IR/ProfileSummary.h"
20#include "llvm/InitializePasses.h"
21#include "llvm/ProfileData/ProfileCommon.h"
22#include "llvm/Support/CommandLine.h"
23#include "llvm/Support/Compiler.h"
24#include <optional>
25using namespace llvm;
26
27namespace llvm {
28
29static cl::opt<bool> PartialProfile(
30 "partial-profile", cl::Hidden, cl::init(Val: false),
31 cl::desc("Specify the current profile is used as a partial profile."));
32
33LLVM_ABI cl::opt<bool> ScalePartialSampleProfileWorkingSetSize(
34 "scale-partial-sample-profile-working-set-size", cl::Hidden, cl::init(Val: true),
35 cl::desc(
36 "If true, scale the working set size of the partial sample profile "
37 "by the partial profile ratio to reflect the size of the program "
38 "being compiled."));
39
40static cl::opt<double> PartialSampleProfileWorkingSetSizeScaleFactor(
41 "partial-sample-profile-working-set-size-scale-factor", cl::Hidden,
42 cl::init(Val: 0.008),
43 cl::desc("The scale factor used to scale the working set size of the "
44 "partial sample profile along with the partial profile ratio. "
45 "This includes the factor of the profile counter per block "
46 "and the factor to scale the working set size to use the same "
47 "shared thresholds as PGO."));
48
49} // end namespace llvm
50
51// The profile summary metadata may be attached either by the frontend or by
52// any backend passes (IR level instrumentation, for example). This method
53// checks if the Summary is null and if so checks if the summary metadata is now
54// available in the module and parses it to get the Summary object.
55void ProfileSummaryInfo::refresh(std::unique_ptr<ProfileSummary> &&Other) {
56 if (Other) {
57 Summary.swap(u&: Other);
58 return;
59 }
60 if (hasProfileSummary())
61 return;
62 // First try to get context sensitive ProfileSummary.
63 auto *SummaryMD = M->getProfileSummary(/* IsCS */ true);
64 if (SummaryMD)
65 Summary.reset(p: ProfileSummary::getFromMD(MD: SummaryMD));
66
67 if (!hasProfileSummary()) {
68 // This will actually return PSK_Instr or PSK_Sample summary.
69 SummaryMD = M->getProfileSummary(/* IsCS */ false);
70 if (SummaryMD)
71 Summary.reset(p: ProfileSummary::getFromMD(MD: SummaryMD));
72 }
73 if (!hasProfileSummary())
74 return;
75 computeThresholds();
76}
77
78std::optional<uint64_t> ProfileSummaryInfo::getProfileCount(
79 const CallBase &Call, BlockFrequencyInfo *BFI, bool AllowSynthetic) const {
80 assert((isa<CallInst>(Call) || isa<InvokeInst>(Call)) &&
81 "We can only get profile count for call/invoke instruction.");
82 if (hasSampleProfile()) {
83 // In sample PGO mode, check if there is a profile metadata on the
84 // instruction. If it is present, determine hotness solely based on that,
85 // since the sampled entry count may not be accurate. If there is no
86 // annotated on the instruction, return std::nullopt.
87 uint64_t TotalCount;
88 if (Call.extractProfTotalWeight(TotalVal&: TotalCount))
89 return TotalCount;
90 return std::nullopt;
91 }
92 if (BFI)
93 return BFI->getBlockProfileCount(BB: Call.getParent(), AllowSynthetic);
94 return std::nullopt;
95}
96
97bool ProfileSummaryInfo::isFunctionHotnessUnknown(const Function &F) const {
98 assert(hasPartialSampleProfile() && "Expect partial sample profile");
99 return !F.getEntryCount();
100}
101
102/// Returns true if the function's entry is a cold. If it returns false, it
103/// either means it is not cold or it is unknown whether it is cold or not (for
104/// example, no profile data is available).
105bool ProfileSummaryInfo::isFunctionEntryCold(const Function *F) const {
106 if (!F)
107 return false;
108 if (F->hasFnAttribute(Kind: Attribute::Cold))
109 return true;
110 if (!hasProfileSummary())
111 return false;
112 auto FunctionCount = F->getEntryCount();
113 // FIXME: The heuristic used below for determining coldness is based on
114 // preliminary SPEC tuning for inliner. This will eventually be a
115 // convenience method that calls isHotCount.
116 return FunctionCount && isColdCount(C: FunctionCount->getCount());
117}
118
119/// Compute the hot and cold thresholds.
120void ProfileSummaryInfo::computeThresholds() {
121 auto &DetailedSummary = Summary->getDetailedSummary();
122 auto &HotEntry = ProfileSummaryBuilder::getEntryForPercentile(
123 DS: DetailedSummary, Percentile: ProfileSummaryCutoffHot);
124 HotCountThreshold =
125 ProfileSummaryBuilder::getHotCountThreshold(DS: DetailedSummary);
126 ColdCountThreshold =
127 ProfileSummaryBuilder::getColdCountThreshold(DS: DetailedSummary);
128 // When the hot and cold thresholds are identical, we would classify
129 // a count value as both hot and cold since we are doing an inclusive check
130 // (see ::is{Hot|Cold}Count(). To avoid this undesirable overlap, ensure the
131 // thresholds are distinct.
132 if (HotCountThreshold == ColdCountThreshold) {
133 if (ColdCountThreshold > 0)
134 (*ColdCountThreshold)--;
135 else
136 (*HotCountThreshold)++;
137 }
138 assert(ColdCountThreshold < HotCountThreshold &&
139 "Cold count threshold should be less than hot count threshold!");
140 if (!hasPartialSampleProfile() || !ScalePartialSampleProfileWorkingSetSize) {
141 HasHugeWorkingSetSize =
142 HotEntry.NumCounts > ProfileSummaryHugeWorkingSetSizeThreshold;
143 HasLargeWorkingSetSize =
144 HotEntry.NumCounts > ProfileSummaryLargeWorkingSetSizeThreshold;
145 } else {
146 // Scale the working set size of the partial sample profile to reflect the
147 // size of the program being compiled.
148 double PartialProfileRatio = Summary->getPartialProfileRatio();
149 uint64_t ScaledHotEntryNumCounts =
150 static_cast<uint64_t>(HotEntry.NumCounts * PartialProfileRatio *
151 PartialSampleProfileWorkingSetSizeScaleFactor);
152 HasHugeWorkingSetSize =
153 ScaledHotEntryNumCounts > ProfileSummaryHugeWorkingSetSizeThreshold;
154 HasLargeWorkingSetSize =
155 ScaledHotEntryNumCounts > ProfileSummaryLargeWorkingSetSizeThreshold;
156 }
157}
158
159std::optional<uint64_t>
160ProfileSummaryInfo::computeThreshold(int PercentileCutoff) const {
161 if (!hasProfileSummary())
162 return std::nullopt;
163 auto [Iter, Inserted] = ThresholdCache.try_emplace(Key: PercentileCutoff);
164 if (!Inserted)
165 return Iter->second;
166 auto &DetailedSummary = Summary->getDetailedSummary();
167 auto &Entry = ProfileSummaryBuilder::getEntryForPercentile(DS: DetailedSummary,
168 Percentile: PercentileCutoff);
169 uint64_t CountThreshold = Entry.MinCount;
170 Iter->second = CountThreshold;
171 return CountThreshold;
172}
173
174bool ProfileSummaryInfo::hasHugeWorkingSetSize() const {
175 return HasHugeWorkingSetSize && *HasHugeWorkingSetSize;
176}
177
178bool ProfileSummaryInfo::hasLargeWorkingSetSize() const {
179 return HasLargeWorkingSetSize && *HasLargeWorkingSetSize;
180}
181
182bool ProfileSummaryInfo::isHotCount(uint64_t C) const {
183 return HotCountThreshold && C >= *HotCountThreshold;
184}
185
186bool ProfileSummaryInfo::isColdCount(uint64_t C) const {
187 return ColdCountThreshold && C <= *ColdCountThreshold;
188}
189
190template <bool isHot>
191bool ProfileSummaryInfo::isHotOrColdCountNthPercentile(int PercentileCutoff,
192 uint64_t C) const {
193 auto CountThreshold = computeThreshold(PercentileCutoff);
194 if (isHot)
195 return CountThreshold && C >= *CountThreshold;
196 else
197 return CountThreshold && C <= *CountThreshold;
198}
199
200bool ProfileSummaryInfo::isHotCountNthPercentile(int PercentileCutoff,
201 uint64_t C) const {
202 return isHotOrColdCountNthPercentile<true>(PercentileCutoff, C);
203}
204
205bool ProfileSummaryInfo::isColdCountNthPercentile(int PercentileCutoff,
206 uint64_t C) const {
207 return isHotOrColdCountNthPercentile<false>(PercentileCutoff, C);
208}
209
210uint64_t ProfileSummaryInfo::getOrCompHotCountThreshold() const {
211 return HotCountThreshold.value_or(UINT64_MAX);
212}
213
214uint64_t ProfileSummaryInfo::getOrCompColdCountThreshold() const {
215 return ColdCountThreshold.value_or(u: 0);
216}
217
218bool ProfileSummaryInfo::isHotCallSite(const CallBase &CB,
219 BlockFrequencyInfo *BFI) const {
220 auto C = getProfileCount(Call: CB, BFI);
221 return C && isHotCount(C: *C);
222}
223
224bool ProfileSummaryInfo::isColdCallSite(const CallBase &CB,
225 BlockFrequencyInfo *BFI) const {
226 auto C = getProfileCount(Call: CB, BFI);
227 if (C)
228 return isColdCount(C: *C);
229
230 // In SamplePGO, if the caller has been sampled, and there is no profile
231 // annotated on the callsite, we consider the callsite as cold.
232 return hasSampleProfile() && CB.getCaller()->hasProfileData();
233}
234
235bool ProfileSummaryInfo::hasPartialSampleProfile() const {
236 return hasProfileSummary() &&
237 Summary->getKind() == ProfileSummary::PSK_Sample &&
238 (PartialProfile || Summary->isPartialProfile());
239}
240
241INITIALIZE_PASS(ProfileSummaryInfoWrapperPass, "profile-summary-info",
242 "Profile summary info", false, true)
243
244ProfileSummaryInfoWrapperPass::ProfileSummaryInfoWrapperPass()
245 : ImmutablePass(ID) {}
246
247bool ProfileSummaryInfoWrapperPass::doInitialization(Module &M) {
248 PSI.reset(p: new ProfileSummaryInfo(M));
249 return false;
250}
251
252bool ProfileSummaryInfoWrapperPass::doFinalization(Module &M) {
253 PSI.reset();
254 return false;
255}
256
257AnalysisKey ProfileSummaryAnalysis::Key;
258ProfileSummaryInfo ProfileSummaryAnalysis::run(Module &M,
259 ModuleAnalysisManager &) {
260 return ProfileSummaryInfo(M);
261}
262
263PreservedAnalyses ProfileSummaryPrinterPass::run(Module &M,
264 ModuleAnalysisManager &AM) {
265 ProfileSummaryInfo &PSI = AM.getResult<ProfileSummaryAnalysis>(IR&: M);
266
267 OS << "Functions in " << M.getName() << " with hot/cold annotations: \n";
268 for (auto &F : M) {
269 OS << F.getName();
270 if (PSI.isFunctionEntryHot(F: &F))
271 OS << " :hot entry ";
272 else if (PSI.isFunctionEntryCold(F: &F))
273 OS << " :cold entry ";
274 OS << "\n";
275 }
276 return PreservedAnalyses::all();
277}
278
279char ProfileSummaryInfoWrapperPass::ID = 0;
280