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