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Rong Xuf430ae42015-12-09 18:08:16 +00001//===-- PGOInstrumentation.cpp - MST-based PGO Instrumentation ------------===//
2//
3// The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file implements PGO instrumentation using a minimum spanning tree based
11// on the following paper:
12// [1] Donald E. Knuth, Francis R. Stevenson. Optimal measurement of points
13// for program frequency counts. BIT Numerical Mathematics 1973, Volume 13,
14// Issue 3, pp 313-322
15// The idea of the algorithm based on the fact that for each node (except for
16// the entry and exit), the sum of incoming edge counts equals the sum of
17// outgoing edge counts. The count of edge on spanning tree can be derived from
18// those edges not on the spanning tree. Knuth proves this method instruments
19// the minimum number of edges.
20//
21// The minimal spanning tree here is actually a maximum weight tree -- on-tree
22// edges have higher frequencies (more likely to execute). The idea is to
23// instrument those less frequently executed edges to reduce the runtime
24// overhead of instrumented binaries.
25//
26// This file contains two passes:
27// (1) Pass PGOInstrumentationGen which instruments the IR to generate edge
Rong Xu13b01dc2016-02-10 18:24:45 +000028// count profile, and generates the instrumentation for indirect call
29// profiling.
Rong Xuf430ae42015-12-09 18:08:16 +000030// (2) Pass PGOInstrumentationUse which reads the edge count profile and
Rong Xu13b01dc2016-02-10 18:24:45 +000031// annotates the branch weights. It also reads the indirect call value
32// profiling records and annotate the indirect call instructions.
33//
Rong Xuf430ae42015-12-09 18:08:16 +000034// To get the precise counter information, These two passes need to invoke at
35// the same compilation point (so they see the same IR). For pass
36// PGOInstrumentationGen, the real work is done in instrumentOneFunc(). For
37// pass PGOInstrumentationUse, the real work in done in class PGOUseFunc and
38// the profile is opened in module level and passed to each PGOUseFunc instance.
39// The shared code for PGOInstrumentationGen and PGOInstrumentationUse is put
40// in class FuncPGOInstrumentation.
41//
42// Class PGOEdge represents a CFG edge and some auxiliary information. Class
43// BBInfo contains auxiliary information for each BB. These two classes are used
44// in pass PGOInstrumentationGen. Class PGOUseEdge and UseBBInfo are the derived
45// class of PGOEdge and BBInfo, respectively. They contains extra data structure
46// used in populating profile counters.
47// The MST implementation is in Class CFGMST (CFGMST.h).
48//
49//===----------------------------------------------------------------------===//
50
Xinliang David Li8aebf442016-05-06 05:49:19 +000051#include "llvm/Transforms/PGOInstrumentation.h"
Rong Xuf430ae42015-12-09 18:08:16 +000052#include "CFGMST.h"
Rong Xuf430ae42015-12-09 18:08:16 +000053#include "llvm/ADT/STLExtras.h"
Rong Xu705f7772016-07-25 18:45:37 +000054#include "llvm/ADT/SmallVector.h"
Rong Xuf430ae42015-12-09 18:08:16 +000055#include "llvm/ADT/Statistic.h"
Rong Xu33c76c02016-02-10 17:18:30 +000056#include "llvm/ADT/Triple.h"
Rong Xuf430ae42015-12-09 18:08:16 +000057#include "llvm/Analysis/BlockFrequencyInfo.h"
58#include "llvm/Analysis/BranchProbabilityInfo.h"
59#include "llvm/Analysis/CFG.h"
Teresa Johnson1e44b5d2016-07-12 21:13:44 +000060#include "llvm/Analysis/IndirectCallSiteVisitor.h"
Rong Xued9fec72016-01-21 18:11:44 +000061#include "llvm/IR/CallSite.h"
Rong Xuf430ae42015-12-09 18:08:16 +000062#include "llvm/IR/DiagnosticInfo.h"
Rong Xu705f7772016-07-25 18:45:37 +000063#include "llvm/IR/GlobalValue.h"
Rong Xuf430ae42015-12-09 18:08:16 +000064#include "llvm/IR/IRBuilder.h"
65#include "llvm/IR/InstIterator.h"
66#include "llvm/IR/Instructions.h"
67#include "llvm/IR/IntrinsicInst.h"
68#include "llvm/IR/MDBuilder.h"
69#include "llvm/IR/Module.h"
70#include "llvm/Pass.h"
71#include "llvm/ProfileData/InstrProfReader.h"
Easwaran Raman5fe04a12016-05-26 22:57:11 +000072#include "llvm/ProfileData/ProfileCommon.h"
Rong Xuf430ae42015-12-09 18:08:16 +000073#include "llvm/Support/BranchProbability.h"
74#include "llvm/Support/Debug.h"
75#include "llvm/Support/JamCRC.h"
Rong Xued9fec72016-01-21 18:11:44 +000076#include "llvm/Transforms/Instrumentation.h"
Rong Xuf430ae42015-12-09 18:08:16 +000077#include "llvm/Transforms/Utils/BasicBlockUtils.h"
Xinliang David Li8aebf442016-05-06 05:49:19 +000078#include <algorithm>
Rong Xuf430ae42015-12-09 18:08:16 +000079#include <string>
Rong Xu705f7772016-07-25 18:45:37 +000080#include <unordered_map>
Rong Xuf430ae42015-12-09 18:08:16 +000081#include <utility>
82#include <vector>
83
84using namespace llvm;
85
86#define DEBUG_TYPE "pgo-instrumentation"
87
88STATISTIC(NumOfPGOInstrument, "Number of edges instrumented.");
Xinliang David Li4ca17332016-09-18 18:34:07 +000089STATISTIC(NumOfPGOSelectInsts, "Number of select instruction instrumented.");
Rong Xuf430ae42015-12-09 18:08:16 +000090STATISTIC(NumOfPGOEdge, "Number of edges.");
91STATISTIC(NumOfPGOBB, "Number of basic-blocks.");
92STATISTIC(NumOfPGOSplit, "Number of critical edge splits.");
93STATISTIC(NumOfPGOFunc, "Number of functions having valid profile counts.");
94STATISTIC(NumOfPGOMismatch, "Number of functions having mismatch profile.");
95STATISTIC(NumOfPGOMissing, "Number of functions without profile.");
Rong Xu13b01dc2016-02-10 18:24:45 +000096STATISTIC(NumOfPGOICall, "Number of indirect call value instrumentations.");
Rong Xuf430ae42015-12-09 18:08:16 +000097
98// Command line option to specify the file to read profile from. This is
99// mainly used for testing.
100static cl::opt<std::string>
101 PGOTestProfileFile("pgo-test-profile-file", cl::init(""), cl::Hidden,
102 cl::value_desc("filename"),
103 cl::desc("Specify the path of profile data file. This is"
104 "mainly for test purpose."));
105
Rong Xuecdc98f2016-03-04 22:08:44 +0000106// Command line option to disable value profiling. The default is false:
Rong Xu13b01dc2016-02-10 18:24:45 +0000107// i.e. value profiling is enabled by default. This is for debug purpose.
Rong Xu9e926e82016-02-29 19:16:04 +0000108static cl::opt<bool> DisableValueProfiling("disable-vp", cl::init(false),
109 cl::Hidden,
110 cl::desc("Disable Value Profiling"));
Rong Xued9fec72016-01-21 18:11:44 +0000111
Rong Xuecdc98f2016-03-04 22:08:44 +0000112// Command line option to set the maximum number of VP annotations to write to
Rong Xu08afb052016-04-28 17:31:22 +0000113// the metadata for a single indirect call callsite.
114static cl::opt<unsigned> MaxNumAnnotations(
115 "icp-max-annotations", cl::init(3), cl::Hidden, cl::ZeroOrMore,
116 cl::desc("Max number of annotations for a single indirect "
117 "call callsite"));
Rong Xuecdc98f2016-03-04 22:08:44 +0000118
Rong Xu705f7772016-07-25 18:45:37 +0000119// Command line option to control appending FunctionHash to the name of a COMDAT
120// function. This is to avoid the hash mismatch caused by the preinliner.
121static cl::opt<bool> DoComdatRenaming(
122 "do-comdat-renaming", cl::init(true), cl::Hidden,
123 cl::desc("Append function hash to the name of COMDAT function to avoid "
124 "function hash mismatch due to the preinliner"));
125
Rong Xu0698de92016-05-13 17:26:06 +0000126// Command line option to enable/disable the warning about missing profile
127// information.
Xinliang David Li76a01082016-08-11 05:09:30 +0000128static cl::opt<bool> PGOWarnMissing("pgo-warn-missing-function",
129 cl::init(false),
130 cl::Hidden);
Rong Xu0698de92016-05-13 17:26:06 +0000131
132// Command line option to enable/disable the warning about a hash mismatch in
133// the profile data.
134static cl::opt<bool> NoPGOWarnMismatch("no-pgo-warn-mismatch", cl::init(false),
135 cl::Hidden);
136
Xinliang David Li4ca17332016-09-18 18:34:07 +0000137// Command line option to enable/disable select instruction instrumentation.
138static cl::opt<bool> PGOInstrSelect("pgo-instr-select", cl::init(true),
139 cl::Hidden);
Rong Xuf430ae42015-12-09 18:08:16 +0000140namespace {
Xinliang David Li4ca17332016-09-18 18:34:07 +0000141
142/// The select instruction visitor plays three roles specified
143/// by the mode. In \c VM_counting mode, it simply counts the number of
144/// select instructions. In \c VM_instrument mode, it inserts code to count
145/// the number times TrueValue of select is taken. In \c VM_annotate mode,
146/// it reads the profile data and annotate the select instruction with metadata.
147enum VisitMode { VM_counting, VM_instrument, VM_annotate };
148class PGOUseFunc;
149
150/// Instruction Visitor class to visit select instructions.
151struct SelectInstVisitor : public InstVisitor<SelectInstVisitor> {
152 Function &F;
153 unsigned NSIs = 0; // Number of select instructions instrumented.
154 VisitMode Mode = VM_counting; // Visiting mode.
155 unsigned *CurCtrIdx = nullptr; // Pointer to current counter index.
156 unsigned TotalNumCtrs = 0; // Total number of counters
157 GlobalVariable *FuncNameVar = nullptr;
158 uint64_t FuncHash = 0;
159 PGOUseFunc *UseFunc = nullptr;
160
161 SelectInstVisitor(Function &Func) : F(Func) {}
162
163 void countSelects(Function &Func) {
164 Mode = VM_counting;
165 visit(Func);
166 }
167 // Visit the IR stream and instrument all select instructions. \p
168 // Ind is a pointer to the counter index variable; \p TotalNC
169 // is the total number of counters; \p FNV is the pointer to the
170 // PGO function name var; \p FHash is the function hash.
171 void instrumentSelects(Function &Func, unsigned *Ind, unsigned TotalNC,
172 GlobalVariable *FNV, uint64_t FHash) {
173 Mode = VM_instrument;
174 CurCtrIdx = Ind;
175 TotalNumCtrs = TotalNC;
176 FuncHash = FHash;
177 FuncNameVar = FNV;
178 visit(Func);
179 }
180
181 // Visit the IR stream and annotate all select instructions.
182 void annotateSelects(Function &Func, PGOUseFunc *UF, unsigned *Ind) {
183 Mode = VM_annotate;
184 UseFunc = UF;
185 CurCtrIdx = Ind;
186 visit(Func);
187 }
188
189 void instrumentOneSelectInst(SelectInst &SI);
190 void annotateOneSelectInst(SelectInst &SI);
191 // Visit \p SI instruction and perform tasks according to visit mode.
192 void visitSelectInst(SelectInst &SI);
193 unsigned getNumOfSelectInsts() const { return NSIs; }
194};
195
Xinliang David Li8aebf442016-05-06 05:49:19 +0000196class PGOInstrumentationGenLegacyPass : public ModulePass {
Rong Xuf430ae42015-12-09 18:08:16 +0000197public:
198 static char ID;
199
Xinliang David Lidfa21c32016-05-09 21:37:12 +0000200 PGOInstrumentationGenLegacyPass() : ModulePass(ID) {
Xinliang David Li8aebf442016-05-06 05:49:19 +0000201 initializePGOInstrumentationGenLegacyPassPass(
202 *PassRegistry::getPassRegistry());
Rong Xuf430ae42015-12-09 18:08:16 +0000203 }
204
Mehdi Amini117296c2016-10-01 02:56:57 +0000205 StringRef getPassName() const override { return "PGOInstrumentationGenPass"; }
Rong Xuf430ae42015-12-09 18:08:16 +0000206
207private:
208 bool runOnModule(Module &M) override;
209
210 void getAnalysisUsage(AnalysisUsage &AU) const override {
211 AU.addRequired<BlockFrequencyInfoWrapperPass>();
212 }
213};
214
Xinliang David Lid55827f2016-05-07 05:39:12 +0000215class PGOInstrumentationUseLegacyPass : public ModulePass {
Rong Xuf430ae42015-12-09 18:08:16 +0000216public:
217 static char ID;
218
219 // Provide the profile filename as the parameter.
Xinliang David Lid55827f2016-05-07 05:39:12 +0000220 PGOInstrumentationUseLegacyPass(std::string Filename = "")
Benjamin Kramer82de7d32016-05-27 14:27:24 +0000221 : ModulePass(ID), ProfileFileName(std::move(Filename)) {
Rong Xuf430ae42015-12-09 18:08:16 +0000222 if (!PGOTestProfileFile.empty())
223 ProfileFileName = PGOTestProfileFile;
Xinliang David Lid55827f2016-05-07 05:39:12 +0000224 initializePGOInstrumentationUseLegacyPassPass(
225 *PassRegistry::getPassRegistry());
Rong Xuf430ae42015-12-09 18:08:16 +0000226 }
227
Mehdi Amini117296c2016-10-01 02:56:57 +0000228 StringRef getPassName() const override { return "PGOInstrumentationUsePass"; }
Rong Xuf430ae42015-12-09 18:08:16 +0000229
230private:
231 std::string ProfileFileName;
Rong Xuf430ae42015-12-09 18:08:16 +0000232
Xinliang David Lida195582016-05-10 21:59:52 +0000233 bool runOnModule(Module &M) override;
Rong Xuf430ae42015-12-09 18:08:16 +0000234 void getAnalysisUsage(AnalysisUsage &AU) const override {
235 AU.addRequired<BlockFrequencyInfoWrapperPass>();
236 }
237};
Xinliang David Li4ca17332016-09-18 18:34:07 +0000238
Rong Xuf430ae42015-12-09 18:08:16 +0000239} // end anonymous namespace
240
Xinliang David Li8aebf442016-05-06 05:49:19 +0000241char PGOInstrumentationGenLegacyPass::ID = 0;
242INITIALIZE_PASS_BEGIN(PGOInstrumentationGenLegacyPass, "pgo-instr-gen",
Rong Xuf430ae42015-12-09 18:08:16 +0000243 "PGO instrumentation.", false, false)
244INITIALIZE_PASS_DEPENDENCY(BlockFrequencyInfoWrapperPass)
245INITIALIZE_PASS_DEPENDENCY(BranchProbabilityInfoWrapperPass)
Xinliang David Li8aebf442016-05-06 05:49:19 +0000246INITIALIZE_PASS_END(PGOInstrumentationGenLegacyPass, "pgo-instr-gen",
Rong Xuf430ae42015-12-09 18:08:16 +0000247 "PGO instrumentation.", false, false)
248
Xinliang David Li8aebf442016-05-06 05:49:19 +0000249ModulePass *llvm::createPGOInstrumentationGenLegacyPass() {
250 return new PGOInstrumentationGenLegacyPass();
Rong Xuf430ae42015-12-09 18:08:16 +0000251}
252
Xinliang David Lid55827f2016-05-07 05:39:12 +0000253char PGOInstrumentationUseLegacyPass::ID = 0;
254INITIALIZE_PASS_BEGIN(PGOInstrumentationUseLegacyPass, "pgo-instr-use",
Rong Xuf430ae42015-12-09 18:08:16 +0000255 "Read PGO instrumentation profile.", false, false)
256INITIALIZE_PASS_DEPENDENCY(BlockFrequencyInfoWrapperPass)
257INITIALIZE_PASS_DEPENDENCY(BranchProbabilityInfoWrapperPass)
Xinliang David Lid55827f2016-05-07 05:39:12 +0000258INITIALIZE_PASS_END(PGOInstrumentationUseLegacyPass, "pgo-instr-use",
Rong Xuf430ae42015-12-09 18:08:16 +0000259 "Read PGO instrumentation profile.", false, false)
260
Xinliang David Lid55827f2016-05-07 05:39:12 +0000261ModulePass *llvm::createPGOInstrumentationUseLegacyPass(StringRef Filename) {
262 return new PGOInstrumentationUseLegacyPass(Filename.str());
Rong Xuf430ae42015-12-09 18:08:16 +0000263}
264
265namespace {
266/// \brief An MST based instrumentation for PGO
267///
268/// Implements a Minimum Spanning Tree (MST) based instrumentation for PGO
269/// in the function level.
270struct PGOEdge {
271 // This class implements the CFG edges. Note the CFG can be a multi-graph.
272 // So there might be multiple edges with same SrcBB and DestBB.
273 const BasicBlock *SrcBB;
274 const BasicBlock *DestBB;
275 uint64_t Weight;
276 bool InMST;
277 bool Removed;
278 bool IsCritical;
279 PGOEdge(const BasicBlock *Src, const BasicBlock *Dest, unsigned W = 1)
280 : SrcBB(Src), DestBB(Dest), Weight(W), InMST(false), Removed(false),
281 IsCritical(false) {}
282 // Return the information string of an edge.
283 const std::string infoString() const {
284 return (Twine(Removed ? "-" : " ") + (InMST ? " " : "*") +
285 (IsCritical ? "c" : " ") + " W=" + Twine(Weight)).str();
286 }
287};
288
289// This class stores the auxiliary information for each BB.
290struct BBInfo {
291 BBInfo *Group;
292 uint32_t Index;
293 uint32_t Rank;
294
295 BBInfo(unsigned IX) : Group(this), Index(IX), Rank(0) {}
296
297 // Return the information string of this object.
298 const std::string infoString() const {
299 return (Twine("Index=") + Twine(Index)).str();
300 }
301};
302
303// This class implements the CFG edges. Note the CFG can be a multi-graph.
304template <class Edge, class BBInfo> class FuncPGOInstrumentation {
305private:
306 Function &F;
307 void computeCFGHash();
Rong Xu705f7772016-07-25 18:45:37 +0000308 void renameComdatFunction();
309 // A map that stores the Comdat group in function F.
310 std::unordered_multimap<Comdat *, GlobalValue *> &ComdatMembers;
Rong Xuf430ae42015-12-09 18:08:16 +0000311
312public:
Xinliang David Li9780fc12016-09-20 22:39:47 +0000313 std::vector<Instruction *> IndirectCallSites;
Xinliang David Li4ca17332016-09-18 18:34:07 +0000314 SelectInstVisitor SIVisitor;
Rong Xuf430ae42015-12-09 18:08:16 +0000315 std::string FuncName;
316 GlobalVariable *FuncNameVar;
317 // CFG hash value for this function.
318 uint64_t FunctionHash;
319
320 // The Minimum Spanning Tree of function CFG.
321 CFGMST<Edge, BBInfo> MST;
322
323 // Give an edge, find the BB that will be instrumented.
324 // Return nullptr if there is no BB to be instrumented.
325 BasicBlock *getInstrBB(Edge *E);
326
327 // Return the auxiliary BB information.
328 BBInfo &getBBInfo(const BasicBlock *BB) const { return MST.getBBInfo(BB); }
329
330 // Dump edges and BB information.
331 void dumpInfo(std::string Str = "") const {
332 MST.dumpEdges(dbgs(), Twine("Dump Function ") + FuncName + " Hash: " +
Rong Xued9fec72016-01-21 18:11:44 +0000333 Twine(FunctionHash) + "\t" + Str);
Rong Xuf430ae42015-12-09 18:08:16 +0000334 }
335
Rong Xu705f7772016-07-25 18:45:37 +0000336 FuncPGOInstrumentation(
337 Function &Func,
338 std::unordered_multimap<Comdat *, GlobalValue *> &ComdatMembers,
339 bool CreateGlobalVar = false, BranchProbabilityInfo *BPI = nullptr,
340 BlockFrequencyInfo *BFI = nullptr)
Xinliang David Li4ca17332016-09-18 18:34:07 +0000341 : F(Func), ComdatMembers(ComdatMembers), SIVisitor(Func), FunctionHash(0),
Rong Xu705f7772016-07-25 18:45:37 +0000342 MST(F, BPI, BFI) {
Xinliang David Li4ca17332016-09-18 18:34:07 +0000343
344 // This should be done before CFG hash computation.
345 SIVisitor.countSelects(Func);
346 NumOfPGOSelectInsts += SIVisitor.getNumOfSelectInsts();
Xinliang David Li9780fc12016-09-20 22:39:47 +0000347 IndirectCallSites = findIndirectCallSites(Func);
Xinliang David Li4ca17332016-09-18 18:34:07 +0000348
Rong Xuf430ae42015-12-09 18:08:16 +0000349 FuncName = getPGOFuncName(F);
350 computeCFGHash();
Rong Xu705f7772016-07-25 18:45:37 +0000351 if (ComdatMembers.size())
352 renameComdatFunction();
Rong Xuf430ae42015-12-09 18:08:16 +0000353 DEBUG(dumpInfo("after CFGMST"));
354
355 NumOfPGOBB += MST.BBInfos.size();
356 for (auto &E : MST.AllEdges) {
357 if (E->Removed)
358 continue;
359 NumOfPGOEdge++;
360 if (!E->InMST)
361 NumOfPGOInstrument++;
362 }
363
364 if (CreateGlobalVar)
365 FuncNameVar = createPGOFuncNameVar(F, FuncName);
Eugene Zelenko6ac3f732016-01-26 18:48:36 +0000366 }
Xinliang David Lid1197612016-08-01 20:25:06 +0000367
368 // Return the number of profile counters needed for the function.
369 unsigned getNumCounters() {
370 unsigned NumCounters = 0;
371 for (auto &E : this->MST.AllEdges) {
372 if (!E->InMST && !E->Removed)
373 NumCounters++;
374 }
Xinliang David Li4ca17332016-09-18 18:34:07 +0000375 return NumCounters + SIVisitor.getNumOfSelectInsts();
Xinliang David Lid1197612016-08-01 20:25:06 +0000376 }
Rong Xuf430ae42015-12-09 18:08:16 +0000377};
378
379// Compute Hash value for the CFG: the lower 32 bits are CRC32 of the index
380// value of each BB in the CFG. The higher 32 bits record the number of edges.
381template <class Edge, class BBInfo>
382void FuncPGOInstrumentation<Edge, BBInfo>::computeCFGHash() {
383 std::vector<char> Indexes;
384 JamCRC JC;
385 for (auto &BB : F) {
386 const TerminatorInst *TI = BB.getTerminator();
387 for (unsigned I = 0, E = TI->getNumSuccessors(); I != E; ++I) {
388 BasicBlock *Succ = TI->getSuccessor(I);
389 uint32_t Index = getBBInfo(Succ).Index;
390 for (int J = 0; J < 4; J++)
391 Indexes.push_back((char)(Index >> (J * 8)));
392 }
393 }
394 JC.update(Indexes);
Xinliang David Li4ca17332016-09-18 18:34:07 +0000395 FunctionHash = (uint64_t)SIVisitor.getNumOfSelectInsts() << 56 |
Xinliang David Li9780fc12016-09-20 22:39:47 +0000396 (uint64_t)IndirectCallSites.size() << 48 |
Rong Xu705f7772016-07-25 18:45:37 +0000397 (uint64_t)MST.AllEdges.size() << 32 | JC.getCRC();
398}
399
400// Check if we can safely rename this Comdat function.
401static bool canRenameComdat(
402 Function &F,
403 std::unordered_multimap<Comdat *, GlobalValue *> &ComdatMembers) {
404 if (F.getName().empty())
405 return false;
406 if (!needsComdatForCounter(F, *(F.getParent())))
407 return false;
408 // Only safe to do if this function may be discarded if it is not used
409 // in the compilation unit.
410 if (!GlobalValue::isDiscardableIfUnused(F.getLinkage()))
411 return false;
412
413 // For AvailableExternallyLinkage functions.
414 if (!F.hasComdat()) {
415 assert(F.getLinkage() == GlobalValue::AvailableExternallyLinkage);
416 return true;
417 }
418
419 // FIXME: Current only handle those Comdat groups that only containing one
420 // function and function aliases.
421 // (1) For a Comdat group containing multiple functions, we need to have a
422 // unique postfix based on the hashes for each function. There is a
423 // non-trivial code refactoring to do this efficiently.
424 // (2) Variables can not be renamed, so we can not rename Comdat function in a
425 // group including global vars.
426 Comdat *C = F.getComdat();
427 for (auto &&CM : make_range(ComdatMembers.equal_range(C))) {
428 if (dyn_cast<GlobalAlias>(CM.second))
429 continue;
430 Function *FM = dyn_cast<Function>(CM.second);
431 if (FM != &F)
432 return false;
433 }
434 return true;
435}
436
437// Append the CFGHash to the Comdat function name.
438template <class Edge, class BBInfo>
439void FuncPGOInstrumentation<Edge, BBInfo>::renameComdatFunction() {
440 if (!canRenameComdat(F, ComdatMembers))
441 return;
Rong Xu0e79f7d2016-10-06 20:38:13 +0000442 std::string OrigName = F.getName().str();
Rong Xu705f7772016-07-25 18:45:37 +0000443 std::string NewFuncName =
444 Twine(F.getName() + "." + Twine(FunctionHash)).str();
445 F.setName(Twine(NewFuncName));
Rong Xu0e79f7d2016-10-06 20:38:13 +0000446 GlobalAlias::create(GlobalValue::WeakAnyLinkage, OrigName, &F);
Rong Xu705f7772016-07-25 18:45:37 +0000447 FuncName = Twine(FuncName + "." + Twine(FunctionHash)).str();
448 Comdat *NewComdat;
449 Module *M = F.getParent();
450 // For AvailableExternallyLinkage functions, change the linkage to
451 // LinkOnceODR and put them into comdat. This is because after renaming, there
452 // is no backup external copy available for the function.
453 if (!F.hasComdat()) {
454 assert(F.getLinkage() == GlobalValue::AvailableExternallyLinkage);
455 NewComdat = M->getOrInsertComdat(StringRef(NewFuncName));
456 F.setLinkage(GlobalValue::LinkOnceODRLinkage);
457 F.setComdat(NewComdat);
458 return;
459 }
460
461 // This function belongs to a single function Comdat group.
462 Comdat *OrigComdat = F.getComdat();
463 std::string NewComdatName =
464 Twine(OrigComdat->getName() + "." + Twine(FunctionHash)).str();
465 NewComdat = M->getOrInsertComdat(StringRef(NewComdatName));
466 NewComdat->setSelectionKind(OrigComdat->getSelectionKind());
467
468 for (auto &&CM : make_range(ComdatMembers.equal_range(OrigComdat))) {
469 if (GlobalAlias *GA = dyn_cast<GlobalAlias>(CM.second)) {
470 // For aliases, change the name directly.
471 assert(dyn_cast<Function>(GA->getAliasee()->stripPointerCasts()) == &F);
Rong Xu0e79f7d2016-10-06 20:38:13 +0000472 std::string OrigGAName = GA->getName().str();
Rong Xu705f7772016-07-25 18:45:37 +0000473 GA->setName(Twine(GA->getName() + "." + Twine(FunctionHash)));
Rong Xu0e79f7d2016-10-06 20:38:13 +0000474 GlobalAlias::create(GlobalValue::WeakAnyLinkage, OrigGAName, GA);
Rong Xu705f7772016-07-25 18:45:37 +0000475 continue;
476 }
477 // Must be a function.
478 Function *CF = dyn_cast<Function>(CM.second);
479 assert(CF);
480 CF->setComdat(NewComdat);
481 }
Rong Xuf430ae42015-12-09 18:08:16 +0000482}
483
484// Given a CFG E to be instrumented, find which BB to place the instrumented
485// code. The function will split the critical edge if necessary.
486template <class Edge, class BBInfo>
487BasicBlock *FuncPGOInstrumentation<Edge, BBInfo>::getInstrBB(Edge *E) {
488 if (E->InMST || E->Removed)
489 return nullptr;
490
491 BasicBlock *SrcBB = const_cast<BasicBlock *>(E->SrcBB);
492 BasicBlock *DestBB = const_cast<BasicBlock *>(E->DestBB);
493 // For a fake edge, instrument the real BB.
494 if (SrcBB == nullptr)
495 return DestBB;
496 if (DestBB == nullptr)
497 return SrcBB;
498
499 // Instrument the SrcBB if it has a single successor,
500 // otherwise, the DestBB if this is not a critical edge.
501 TerminatorInst *TI = SrcBB->getTerminator();
502 if (TI->getNumSuccessors() <= 1)
503 return SrcBB;
504 if (!E->IsCritical)
505 return DestBB;
506
507 // For a critical edge, we have to split. Instrument the newly
508 // created BB.
509 NumOfPGOSplit++;
510 DEBUG(dbgs() << "Split critical edge: " << getBBInfo(SrcBB).Index << " --> "
511 << getBBInfo(DestBB).Index << "\n");
512 unsigned SuccNum = GetSuccessorNumber(SrcBB, DestBB);
513 BasicBlock *InstrBB = SplitCriticalEdge(TI, SuccNum);
514 assert(InstrBB && "Critical edge is not split");
515
516 E->Removed = true;
517 return InstrBB;
518}
519
Rong Xued9fec72016-01-21 18:11:44 +0000520// Visit all edge and instrument the edges not in MST, and do value profiling.
Rong Xuf430ae42015-12-09 18:08:16 +0000521// Critical edges will be split.
Rong Xu705f7772016-07-25 18:45:37 +0000522static void instrumentOneFunc(
523 Function &F, Module *M, BranchProbabilityInfo *BPI, BlockFrequencyInfo *BFI,
524 std::unordered_multimap<Comdat *, GlobalValue *> &ComdatMembers) {
Rong Xu705f7772016-07-25 18:45:37 +0000525 FuncPGOInstrumentation<PGOEdge, BBInfo> FuncInfo(F, ComdatMembers, true, BPI,
526 BFI);
Xinliang David Lid1197612016-08-01 20:25:06 +0000527 unsigned NumCounters = FuncInfo.getNumCounters();
528
Rong Xuf430ae42015-12-09 18:08:16 +0000529 uint32_t I = 0;
Rong Xued9fec72016-01-21 18:11:44 +0000530 Type *I8PtrTy = Type::getInt8PtrTy(M->getContext());
Rong Xuf430ae42015-12-09 18:08:16 +0000531 for (auto &E : FuncInfo.MST.AllEdges) {
532 BasicBlock *InstrBB = FuncInfo.getInstrBB(E.get());
533 if (!InstrBB)
534 continue;
535
536 IRBuilder<> Builder(InstrBB, InstrBB->getFirstInsertionPt());
537 assert(Builder.GetInsertPoint() != InstrBB->end() &&
538 "Cannot get the Instrumentation point");
Rong Xuf430ae42015-12-09 18:08:16 +0000539 Builder.CreateCall(
540 Intrinsic::getDeclaration(M, Intrinsic::instrprof_increment),
541 {llvm::ConstantExpr::getBitCast(FuncInfo.FuncNameVar, I8PtrTy),
542 Builder.getInt64(FuncInfo.FunctionHash), Builder.getInt32(NumCounters),
543 Builder.getInt32(I++)});
544 }
Xinliang David Li4ca17332016-09-18 18:34:07 +0000545
546 // Now instrument select instructions:
547 FuncInfo.SIVisitor.instrumentSelects(F, &I, NumCounters, FuncInfo.FuncNameVar,
548 FuncInfo.FunctionHash);
Xinliang David Lid1197612016-08-01 20:25:06 +0000549 assert(I == NumCounters);
Rong Xued9fec72016-01-21 18:11:44 +0000550
551 if (DisableValueProfiling)
552 return;
553
554 unsigned NumIndirectCallSites = 0;
Xinliang David Li9780fc12016-09-20 22:39:47 +0000555 for (auto &I : FuncInfo.IndirectCallSites) {
Rong Xued9fec72016-01-21 18:11:44 +0000556 CallSite CS(I);
557 Value *Callee = CS.getCalledValue();
558 DEBUG(dbgs() << "Instrument one indirect call: CallSite Index = "
559 << NumIndirectCallSites << "\n");
560 IRBuilder<> Builder(I);
561 assert(Builder.GetInsertPoint() != I->getParent()->end() &&
562 "Cannot get the Instrumentation point");
563 Builder.CreateCall(
564 Intrinsic::getDeclaration(M, Intrinsic::instrprof_value_profile),
565 {llvm::ConstantExpr::getBitCast(FuncInfo.FuncNameVar, I8PtrTy),
566 Builder.getInt64(FuncInfo.FunctionHash),
567 Builder.CreatePtrToInt(Callee, Builder.getInt64Ty()),
568 Builder.getInt32(llvm::InstrProfValueKind::IPVK_IndirectCallTarget),
569 Builder.getInt32(NumIndirectCallSites++)});
570 }
571 NumOfPGOICall += NumIndirectCallSites;
Rong Xuf430ae42015-12-09 18:08:16 +0000572}
573
574// This class represents a CFG edge in profile use compilation.
575struct PGOUseEdge : public PGOEdge {
576 bool CountValid;
577 uint64_t CountValue;
578 PGOUseEdge(const BasicBlock *Src, const BasicBlock *Dest, unsigned W = 1)
579 : PGOEdge(Src, Dest, W), CountValid(false), CountValue(0) {}
580
581 // Set edge count value
582 void setEdgeCount(uint64_t Value) {
583 CountValue = Value;
584 CountValid = true;
585 }
586
587 // Return the information string for this object.
588 const std::string infoString() const {
589 if (!CountValid)
590 return PGOEdge::infoString();
Rong Xu9e926e82016-02-29 19:16:04 +0000591 return (Twine(PGOEdge::infoString()) + " Count=" + Twine(CountValue))
592 .str();
Rong Xuf430ae42015-12-09 18:08:16 +0000593 }
594};
595
596typedef SmallVector<PGOUseEdge *, 2> DirectEdges;
597
598// This class stores the auxiliary information for each BB.
599struct UseBBInfo : public BBInfo {
600 uint64_t CountValue;
601 bool CountValid;
602 int32_t UnknownCountInEdge;
603 int32_t UnknownCountOutEdge;
604 DirectEdges InEdges;
605 DirectEdges OutEdges;
606 UseBBInfo(unsigned IX)
607 : BBInfo(IX), CountValue(0), CountValid(false), UnknownCountInEdge(0),
608 UnknownCountOutEdge(0) {}
609 UseBBInfo(unsigned IX, uint64_t C)
610 : BBInfo(IX), CountValue(C), CountValid(true), UnknownCountInEdge(0),
611 UnknownCountOutEdge(0) {}
612
613 // Set the profile count value for this BB.
614 void setBBInfoCount(uint64_t Value) {
615 CountValue = Value;
616 CountValid = true;
617 }
618
619 // Return the information string of this object.
620 const std::string infoString() const {
621 if (!CountValid)
622 return BBInfo::infoString();
623 return (Twine(BBInfo::infoString()) + " Count=" + Twine(CountValue)).str();
624 }
625};
626
627// Sum up the count values for all the edges.
628static uint64_t sumEdgeCount(const ArrayRef<PGOUseEdge *> Edges) {
629 uint64_t Total = 0;
630 for (auto &E : Edges) {
631 if (E->Removed)
632 continue;
633 Total += E->CountValue;
634 }
635 return Total;
636}
637
638class PGOUseFunc {
Rong Xu6090afd2016-03-28 17:08:56 +0000639public:
Rong Xu705f7772016-07-25 18:45:37 +0000640 PGOUseFunc(Function &Func, Module *Modu,
641 std::unordered_multimap<Comdat *, GlobalValue *> &ComdatMembers,
642 BranchProbabilityInfo *BPI = nullptr,
Rong Xu6090afd2016-03-28 17:08:56 +0000643 BlockFrequencyInfo *BFI = nullptr)
Rong Xu705f7772016-07-25 18:45:37 +0000644 : F(Func), M(Modu), FuncInfo(Func, ComdatMembers, false, BPI, BFI),
Sean Silva9dd4b5c2016-05-28 03:56:25 +0000645 FreqAttr(FFA_Normal) {}
Rong Xu6090afd2016-03-28 17:08:56 +0000646
647 // Read counts for the instrumented BB from profile.
648 bool readCounters(IndexedInstrProfReader *PGOReader);
649
650 // Populate the counts for all BBs.
651 void populateCounters();
652
653 // Set the branch weights based on the count values.
654 void setBranchWeights();
655
656 // Annotate the indirect call sites.
657 void annotateIndirectCallSites();
658
Sean Silva9dd4b5c2016-05-28 03:56:25 +0000659 // The hotness of the function from the profile count.
660 enum FuncFreqAttr { FFA_Normal, FFA_Cold, FFA_Hot };
661
662 // Return the function hotness from the profile.
663 FuncFreqAttr getFuncFreqAttr() const { return FreqAttr; }
664
Rong Xu705f7772016-07-25 18:45:37 +0000665 // Return the function hash.
666 uint64_t getFuncHash() const { return FuncInfo.FunctionHash; }
Easwaran Raman5fe04a12016-05-26 22:57:11 +0000667 // Return the profile record for this function;
668 InstrProfRecord &getProfileRecord() { return ProfileRecord; }
669
Xinliang David Li4ca17332016-09-18 18:34:07 +0000670 // Return the auxiliary BB information.
671 UseBBInfo &getBBInfo(const BasicBlock *BB) const {
672 return FuncInfo.getBBInfo(BB);
673 }
674
Rong Xuf430ae42015-12-09 18:08:16 +0000675private:
676 Function &F;
677 Module *M;
678 // This member stores the shared information with class PGOGenFunc.
679 FuncPGOInstrumentation<PGOUseEdge, UseBBInfo> FuncInfo;
680
Sean Silva9dd4b5c2016-05-28 03:56:25 +0000681 // The maximum count value in the profile. This is only used in PGO use
682 // compilation.
683 uint64_t ProgramMaxCount;
684
Rong Xu13b01dc2016-02-10 18:24:45 +0000685 // ProfileRecord for this function.
686 InstrProfRecord ProfileRecord;
687
Sean Silva9dd4b5c2016-05-28 03:56:25 +0000688 // Function hotness info derived from profile.
689 FuncFreqAttr FreqAttr;
690
Rong Xuf430ae42015-12-09 18:08:16 +0000691 // Find the Instrumented BB and set the value.
692 void setInstrumentedCounts(const std::vector<uint64_t> &CountFromProfile);
693
694 // Set the edge counter value for the unknown edge -- there should be only
695 // one unknown edge.
696 void setEdgeCount(DirectEdges &Edges, uint64_t Value);
697
698 // Return FuncName string;
699 const std::string getFuncName() const { return FuncInfo.FuncName; }
Sean Silva9dd4b5c2016-05-28 03:56:25 +0000700
701 // Set the hot/cold inline hints based on the count values.
702 // FIXME: This function should be removed once the functionality in
703 // the inliner is implemented.
704 void markFunctionAttributes(uint64_t EntryCount, uint64_t MaxCount) {
705 if (ProgramMaxCount == 0)
706 return;
707 // Threshold of the hot functions.
708 const BranchProbability HotFunctionThreshold(1, 100);
709 // Threshold of the cold functions.
710 const BranchProbability ColdFunctionThreshold(2, 10000);
711 if (EntryCount >= HotFunctionThreshold.scale(ProgramMaxCount))
712 FreqAttr = FFA_Hot;
713 else if (MaxCount <= ColdFunctionThreshold.scale(ProgramMaxCount))
714 FreqAttr = FFA_Cold;
715 }
Rong Xuf430ae42015-12-09 18:08:16 +0000716};
717
718// Visit all the edges and assign the count value for the instrumented
719// edges and the BB.
720void PGOUseFunc::setInstrumentedCounts(
721 const std::vector<uint64_t> &CountFromProfile) {
722
Xinliang David Lid1197612016-08-01 20:25:06 +0000723 assert(FuncInfo.getNumCounters() == CountFromProfile.size());
Rong Xuf430ae42015-12-09 18:08:16 +0000724 // Use a worklist as we will update the vector during the iteration.
725 std::vector<PGOUseEdge *> WorkList;
726 for (auto &E : FuncInfo.MST.AllEdges)
727 WorkList.push_back(E.get());
728
729 uint32_t I = 0;
730 for (auto &E : WorkList) {
731 BasicBlock *InstrBB = FuncInfo.getInstrBB(E);
732 if (!InstrBB)
733 continue;
734 uint64_t CountValue = CountFromProfile[I++];
735 if (!E->Removed) {
736 getBBInfo(InstrBB).setBBInfoCount(CountValue);
737 E->setEdgeCount(CountValue);
738 continue;
739 }
740
741 // Need to add two new edges.
742 BasicBlock *SrcBB = const_cast<BasicBlock *>(E->SrcBB);
743 BasicBlock *DestBB = const_cast<BasicBlock *>(E->DestBB);
744 // Add new edge of SrcBB->InstrBB.
745 PGOUseEdge &NewEdge = FuncInfo.MST.addEdge(SrcBB, InstrBB, 0);
746 NewEdge.setEdgeCount(CountValue);
747 // Add new edge of InstrBB->DestBB.
748 PGOUseEdge &NewEdge1 = FuncInfo.MST.addEdge(InstrBB, DestBB, 0);
749 NewEdge1.setEdgeCount(CountValue);
750 NewEdge1.InMST = true;
751 getBBInfo(InstrBB).setBBInfoCount(CountValue);
752 }
Xinliang David Li4ca17332016-09-18 18:34:07 +0000753 // Now annotate select instructions
754 FuncInfo.SIVisitor.annotateSelects(F, this, &I);
Xinliang David Lid1197612016-08-01 20:25:06 +0000755 assert(I == CountFromProfile.size());
Rong Xuf430ae42015-12-09 18:08:16 +0000756}
757
758// Set the count value for the unknown edge. There should be one and only one
759// unknown edge in Edges vector.
760void PGOUseFunc::setEdgeCount(DirectEdges &Edges, uint64_t Value) {
761 for (auto &E : Edges) {
762 if (E->CountValid)
763 continue;
764 E->setEdgeCount(Value);
765
766 getBBInfo(E->SrcBB).UnknownCountOutEdge--;
767 getBBInfo(E->DestBB).UnknownCountInEdge--;
768 return;
769 }
770 llvm_unreachable("Cannot find the unknown count edge");
771}
772
773// Read the profile from ProfileFileName and assign the value to the
774// instrumented BB and the edges. This function also updates ProgramMaxCount.
775// Return true if the profile are successfully read, and false on errors.
776bool PGOUseFunc::readCounters(IndexedInstrProfReader *PGOReader) {
777 auto &Ctx = M->getContext();
Vedant Kumar9152fd12016-05-19 03:54:45 +0000778 Expected<InstrProfRecord> Result =
Rong Xuf430ae42015-12-09 18:08:16 +0000779 PGOReader->getInstrProfRecord(FuncInfo.FuncName, FuncInfo.FunctionHash);
Vedant Kumar9152fd12016-05-19 03:54:45 +0000780 if (Error E = Result.takeError()) {
781 handleAllErrors(std::move(E), [&](const InstrProfError &IPE) {
782 auto Err = IPE.get();
783 bool SkipWarning = false;
784 if (Err == instrprof_error::unknown_function) {
785 NumOfPGOMissing++;
Xinliang David Li76a01082016-08-11 05:09:30 +0000786 SkipWarning = !PGOWarnMissing;
Vedant Kumar9152fd12016-05-19 03:54:45 +0000787 } else if (Err == instrprof_error::hash_mismatch ||
788 Err == instrprof_error::malformed) {
789 NumOfPGOMismatch++;
790 SkipWarning = NoPGOWarnMismatch;
791 }
Rong Xuf430ae42015-12-09 18:08:16 +0000792
Vedant Kumar9152fd12016-05-19 03:54:45 +0000793 if (SkipWarning)
794 return;
795
796 std::string Msg = IPE.message() + std::string(" ") + F.getName().str();
797 Ctx.diagnose(
798 DiagnosticInfoPGOProfile(M->getName().data(), Msg, DS_Warning));
799 });
Rong Xuf430ae42015-12-09 18:08:16 +0000800 return false;
801 }
Rong Xu13b01dc2016-02-10 18:24:45 +0000802 ProfileRecord = std::move(Result.get());
803 std::vector<uint64_t> &CountFromProfile = ProfileRecord.Counts;
Rong Xuf430ae42015-12-09 18:08:16 +0000804
805 NumOfPGOFunc++;
806 DEBUG(dbgs() << CountFromProfile.size() << " counts\n");
807 uint64_t ValueSum = 0;
808 for (unsigned I = 0, S = CountFromProfile.size(); I < S; I++) {
809 DEBUG(dbgs() << " " << I << ": " << CountFromProfile[I] << "\n");
810 ValueSum += CountFromProfile[I];
811 }
812
813 DEBUG(dbgs() << "SUM = " << ValueSum << "\n");
814
815 getBBInfo(nullptr).UnknownCountOutEdge = 2;
816 getBBInfo(nullptr).UnknownCountInEdge = 2;
817
818 setInstrumentedCounts(CountFromProfile);
Sean Silva9dd4b5c2016-05-28 03:56:25 +0000819 ProgramMaxCount = PGOReader->getMaximumFunctionCount();
Rong Xuf430ae42015-12-09 18:08:16 +0000820 return true;
821}
822
823// Populate the counters from instrumented BBs to all BBs.
824// In the end of this operation, all BBs should have a valid count value.
825void PGOUseFunc::populateCounters() {
826 // First set up Count variable for all BBs.
827 for (auto &E : FuncInfo.MST.AllEdges) {
828 if (E->Removed)
829 continue;
830
831 const BasicBlock *SrcBB = E->SrcBB;
832 const BasicBlock *DestBB = E->DestBB;
833 UseBBInfo &SrcInfo = getBBInfo(SrcBB);
834 UseBBInfo &DestInfo = getBBInfo(DestBB);
835 SrcInfo.OutEdges.push_back(E.get());
836 DestInfo.InEdges.push_back(E.get());
837 SrcInfo.UnknownCountOutEdge++;
838 DestInfo.UnknownCountInEdge++;
839
840 if (!E->CountValid)
841 continue;
842 DestInfo.UnknownCountInEdge--;
843 SrcInfo.UnknownCountOutEdge--;
844 }
845
846 bool Changes = true;
847 unsigned NumPasses = 0;
848 while (Changes) {
849 NumPasses++;
850 Changes = false;
851
852 // For efficient traversal, it's better to start from the end as most
853 // of the instrumented edges are at the end.
854 for (auto &BB : reverse(F)) {
855 UseBBInfo &Count = getBBInfo(&BB);
856 if (!Count.CountValid) {
857 if (Count.UnknownCountOutEdge == 0) {
858 Count.CountValue = sumEdgeCount(Count.OutEdges);
859 Count.CountValid = true;
860 Changes = true;
861 } else if (Count.UnknownCountInEdge == 0) {
862 Count.CountValue = sumEdgeCount(Count.InEdges);
863 Count.CountValid = true;
864 Changes = true;
865 }
866 }
867 if (Count.CountValid) {
868 if (Count.UnknownCountOutEdge == 1) {
869 uint64_t Total = Count.CountValue - sumEdgeCount(Count.OutEdges);
870 setEdgeCount(Count.OutEdges, Total);
871 Changes = true;
872 }
873 if (Count.UnknownCountInEdge == 1) {
874 uint64_t Total = Count.CountValue - sumEdgeCount(Count.InEdges);
875 setEdgeCount(Count.InEdges, Total);
876 Changes = true;
877 }
878 }
879 }
880 }
881
882 DEBUG(dbgs() << "Populate counts in " << NumPasses << " passes.\n");
Sean Silva8c7e1212016-05-28 04:19:45 +0000883#ifndef NDEBUG
Sean Silva9dd4b5c2016-05-28 03:56:25 +0000884 // Assert every BB has a valid counter.
Sean Silva8c7e1212016-05-28 04:19:45 +0000885 for (auto &BB : F)
886 assert(getBBInfo(&BB).CountValid && "BB count is not valid");
887#endif
Sean Silva9dd4b5c2016-05-28 03:56:25 +0000888 uint64_t FuncEntryCount = getBBInfo(&*F.begin()).CountValue;
Sean Silva02b9d892016-05-28 04:05:36 +0000889 F.setEntryCount(FuncEntryCount);
Sean Silva9dd4b5c2016-05-28 03:56:25 +0000890 uint64_t FuncMaxCount = FuncEntryCount;
Sean Silva8c7e1212016-05-28 04:19:45 +0000891 for (auto &BB : F)
892 FuncMaxCount = std::max(FuncMaxCount, getBBInfo(&BB).CountValue);
Sean Silva9dd4b5c2016-05-28 03:56:25 +0000893 markFunctionAttributes(FuncEntryCount, FuncMaxCount);
Rong Xuf430ae42015-12-09 18:08:16 +0000894
895 DEBUG(FuncInfo.dumpInfo("after reading profile."));
896}
897
Xinliang David Li4ca17332016-09-18 18:34:07 +0000898static void setProfMetadata(Module *M, Instruction *TI,
Xinliang David Li63248ab2016-08-19 06:31:45 +0000899 ArrayRef<uint64_t> EdgeCounts, uint64_t MaxCount) {
Xinliang David Li2c933682016-08-19 05:31:33 +0000900 MDBuilder MDB(M->getContext());
901 assert(MaxCount > 0 && "Bad max count");
902 uint64_t Scale = calculateCountScale(MaxCount);
903 SmallVector<unsigned, 4> Weights;
904 for (const auto &ECI : EdgeCounts)
905 Weights.push_back(scaleBranchCount(ECI, Scale));
906
907 DEBUG(dbgs() << "Weight is: ";
908 for (const auto &W : Weights) { dbgs() << W << " "; }
909 dbgs() << "\n";);
910 TI->setMetadata(llvm::LLVMContext::MD_prof, MDB.createBranchWeights(Weights));
911}
912
Rong Xuf430ae42015-12-09 18:08:16 +0000913// Assign the scaled count values to the BB with multiple out edges.
914void PGOUseFunc::setBranchWeights() {
915 // Generate MD_prof metadata for every branch instruction.
916 DEBUG(dbgs() << "\nSetting branch weights.\n");
Rong Xuf430ae42015-12-09 18:08:16 +0000917 for (auto &BB : F) {
918 TerminatorInst *TI = BB.getTerminator();
919 if (TI->getNumSuccessors() < 2)
920 continue;
921 if (!isa<BranchInst>(TI) && !isa<SwitchInst>(TI))
922 continue;
923 if (getBBInfo(&BB).CountValue == 0)
924 continue;
925
926 // We have a non-zero Branch BB.
927 const UseBBInfo &BBCountInfo = getBBInfo(&BB);
928 unsigned Size = BBCountInfo.OutEdges.size();
Xinliang David Li63248ab2016-08-19 06:31:45 +0000929 SmallVector<uint64_t, 2> EdgeCounts(Size, 0);
Rong Xuf430ae42015-12-09 18:08:16 +0000930 uint64_t MaxCount = 0;
931 for (unsigned s = 0; s < Size; s++) {
932 const PGOUseEdge *E = BBCountInfo.OutEdges[s];
933 const BasicBlock *SrcBB = E->SrcBB;
934 const BasicBlock *DestBB = E->DestBB;
Eugene Zelenko6ac3f732016-01-26 18:48:36 +0000935 if (DestBB == nullptr)
Rong Xuf430ae42015-12-09 18:08:16 +0000936 continue;
937 unsigned SuccNum = GetSuccessorNumber(SrcBB, DestBB);
938 uint64_t EdgeCount = E->CountValue;
939 if (EdgeCount > MaxCount)
940 MaxCount = EdgeCount;
941 EdgeCounts[SuccNum] = EdgeCount;
942 }
Xinliang David Li2c933682016-08-19 05:31:33 +0000943 setProfMetadata(M, TI, EdgeCounts, MaxCount);
Rong Xuf430ae42015-12-09 18:08:16 +0000944 }
945}
Rong Xu13b01dc2016-02-10 18:24:45 +0000946
Xinliang David Li4ca17332016-09-18 18:34:07 +0000947void SelectInstVisitor::instrumentOneSelectInst(SelectInst &SI) {
948 Module *M = F.getParent();
949 IRBuilder<> Builder(&SI);
950 Type *Int64Ty = Builder.getInt64Ty();
951 Type *I8PtrTy = Builder.getInt8PtrTy();
952 auto *Step = Builder.CreateZExt(SI.getCondition(), Int64Ty);
953 Builder.CreateCall(
954 Intrinsic::getDeclaration(M, Intrinsic::instrprof_increment_step),
955 {llvm::ConstantExpr::getBitCast(FuncNameVar, I8PtrTy),
956 Builder.getInt64(FuncHash),
957 Builder.getInt32(TotalNumCtrs), Builder.getInt32(*CurCtrIdx), Step});
958 ++(*CurCtrIdx);
959}
960
961void SelectInstVisitor::annotateOneSelectInst(SelectInst &SI) {
962 std::vector<uint64_t> &CountFromProfile = UseFunc->getProfileRecord().Counts;
963 assert(*CurCtrIdx < CountFromProfile.size() &&
964 "Out of bound access of counters");
965 uint64_t SCounts[2];
966 SCounts[0] = CountFromProfile[*CurCtrIdx]; // True count
967 ++(*CurCtrIdx);
968 uint64_t TotalCount = UseFunc->getBBInfo(SI.getParent()).CountValue;
969 // False Count
970 SCounts[1] = (TotalCount > SCounts[0] ? TotalCount - SCounts[0] : 0);
971 uint64_t MaxCount = std::max(SCounts[0], SCounts[1]);
Xinliang David Lic7368282016-09-20 20:20:01 +0000972 if (MaxCount)
973 setProfMetadata(F.getParent(), &SI, SCounts, MaxCount);
Xinliang David Li4ca17332016-09-18 18:34:07 +0000974}
975
976void SelectInstVisitor::visitSelectInst(SelectInst &SI) {
977 if (!PGOInstrSelect)
978 return;
979 // FIXME: do not handle this yet.
980 if (SI.getCondition()->getType()->isVectorTy())
981 return;
982
983 NSIs++;
984 switch (Mode) {
985 case VM_counting:
986 return;
987 case VM_instrument:
988 instrumentOneSelectInst(SI);
Simon Pilgrimf33a6b72016-09-18 21:08:35 +0000989 return;
Xinliang David Li4ca17332016-09-18 18:34:07 +0000990 case VM_annotate:
991 annotateOneSelectInst(SI);
Simon Pilgrimf33a6b72016-09-18 21:08:35 +0000992 return;
Xinliang David Li4ca17332016-09-18 18:34:07 +0000993 }
Simon Pilgrimf33a6b72016-09-18 21:08:35 +0000994
995 llvm_unreachable("Unknown visiting mode");
Xinliang David Li4ca17332016-09-18 18:34:07 +0000996}
997
Rong Xu13b01dc2016-02-10 18:24:45 +0000998// Traverse all the indirect callsites and annotate the instructions.
999void PGOUseFunc::annotateIndirectCallSites() {
1000 if (DisableValueProfiling)
1001 return;
1002
Rong Xu8e8fe852016-04-01 16:43:30 +00001003 // Create the PGOFuncName meta data.
Rong Xuf8f051c2016-04-22 21:00:17 +00001004 createPGOFuncNameMetadata(F, FuncInfo.FuncName);
Rong Xub5341662016-03-30 18:37:52 +00001005
Rong Xu13b01dc2016-02-10 18:24:45 +00001006 unsigned IndirectCallSiteIndex = 0;
Xinliang David Li9780fc12016-09-20 22:39:47 +00001007 auto &IndirectCallSites = FuncInfo.IndirectCallSites;
Rong Xu9e926e82016-02-29 19:16:04 +00001008 unsigned NumValueSites =
Rong Xu13b01dc2016-02-10 18:24:45 +00001009 ProfileRecord.getNumValueSites(IPVK_IndirectCallTarget);
Rong Xu0eb36032016-04-01 23:16:44 +00001010 if (NumValueSites != IndirectCallSites.size()) {
Rong Xu13b01dc2016-02-10 18:24:45 +00001011 std::string Msg =
1012 std::string("Inconsistent number of indirect call sites: ") +
Rong Xu9e926e82016-02-29 19:16:04 +00001013 F.getName().str();
Rong Xu13b01dc2016-02-10 18:24:45 +00001014 auto &Ctx = M->getContext();
1015 Ctx.diagnose(
1016 DiagnosticInfoPGOProfile(M->getName().data(), Msg, DS_Warning));
1017 return;
1018 }
1019
Rong Xu0eb36032016-04-01 23:16:44 +00001020 for (auto &I : IndirectCallSites) {
Rong Xu13b01dc2016-02-10 18:24:45 +00001021 DEBUG(dbgs() << "Read one indirect call instrumentation: Index="
Rong Xu9e926e82016-02-29 19:16:04 +00001022 << IndirectCallSiteIndex << " out of " << NumValueSites
1023 << "\n");
Rong Xu13b01dc2016-02-10 18:24:45 +00001024 annotateValueSite(*M, *I, ProfileRecord, IPVK_IndirectCallTarget,
Rong Xuecdc98f2016-03-04 22:08:44 +00001025 IndirectCallSiteIndex, MaxNumAnnotations);
Rong Xu13b01dc2016-02-10 18:24:45 +00001026 IndirectCallSiteIndex++;
1027 }
1028}
Rong Xuf430ae42015-12-09 18:08:16 +00001029} // end anonymous namespace
1030
Xinliang David Lid382e9d2016-07-22 04:46:56 +00001031// Create a COMDAT variable INSTR_PROF_RAW_VERSION_VAR to make the runtime
Rong Xu33c76c02016-02-10 17:18:30 +00001032// aware this is an ir_level profile so it can set the version flag.
1033static void createIRLevelProfileFlagVariable(Module &M) {
1034 Type *IntTy64 = Type::getInt64Ty(M.getContext());
1035 uint64_t ProfileVersion = (INSTR_PROF_RAW_VERSION | VARIANT_MASK_IR_PROF);
Rong Xu9e926e82016-02-29 19:16:04 +00001036 auto IRLevelVersionVariable = new GlobalVariable(
1037 M, IntTy64, true, GlobalVariable::ExternalLinkage,
1038 Constant::getIntegerValue(IntTy64, APInt(64, ProfileVersion)),
Xinliang David Lid382e9d2016-07-22 04:46:56 +00001039 INSTR_PROF_QUOTE(INSTR_PROF_RAW_VERSION_VAR));
Rong Xu33c76c02016-02-10 17:18:30 +00001040 IRLevelVersionVariable->setVisibility(GlobalValue::DefaultVisibility);
1041 Triple TT(M.getTargetTriple());
Xinliang David Li11c849c2016-05-27 16:22:03 +00001042 if (!TT.supportsCOMDAT())
Rong Xuca28a0a2016-05-11 00:31:59 +00001043 IRLevelVersionVariable->setLinkage(GlobalValue::WeakAnyLinkage);
Rong Xu33c76c02016-02-10 17:18:30 +00001044 else
Rong Xu9e926e82016-02-29 19:16:04 +00001045 IRLevelVersionVariable->setComdat(M.getOrInsertComdat(
Xinliang David Lid382e9d2016-07-22 04:46:56 +00001046 StringRef(INSTR_PROF_QUOTE(INSTR_PROF_RAW_VERSION_VAR))));
Rong Xu33c76c02016-02-10 17:18:30 +00001047}
1048
Rong Xu705f7772016-07-25 18:45:37 +00001049// Collect the set of members for each Comdat in module M and store
1050// in ComdatMembers.
1051static void collectComdatMembers(
1052 Module &M,
1053 std::unordered_multimap<Comdat *, GlobalValue *> &ComdatMembers) {
1054 if (!DoComdatRenaming)
1055 return;
1056 for (Function &F : M)
1057 if (Comdat *C = F.getComdat())
1058 ComdatMembers.insert(std::make_pair(C, &F));
1059 for (GlobalVariable &GV : M.globals())
1060 if (Comdat *C = GV.getComdat())
1061 ComdatMembers.insert(std::make_pair(C, &GV));
1062 for (GlobalAlias &GA : M.aliases())
1063 if (Comdat *C = GA.getComdat())
1064 ComdatMembers.insert(std::make_pair(C, &GA));
1065}
1066
Xinliang David Li5ad7c822016-05-02 20:33:59 +00001067static bool InstrumentAllFunctions(
Xinliang David Lidfa21c32016-05-09 21:37:12 +00001068 Module &M, function_ref<BranchProbabilityInfo *(Function &)> LookupBPI,
1069 function_ref<BlockFrequencyInfo *(Function &)> LookupBFI) {
Rong Xu33c76c02016-02-10 17:18:30 +00001070 createIRLevelProfileFlagVariable(M);
Rong Xu705f7772016-07-25 18:45:37 +00001071 std::unordered_multimap<Comdat *, GlobalValue *> ComdatMembers;
1072 collectComdatMembers(M, ComdatMembers);
1073
Rong Xuf430ae42015-12-09 18:08:16 +00001074 for (auto &F : M) {
1075 if (F.isDeclaration())
1076 continue;
Xinliang David Lidfa21c32016-05-09 21:37:12 +00001077 auto *BPI = LookupBPI(F);
1078 auto *BFI = LookupBFI(F);
Rong Xu705f7772016-07-25 18:45:37 +00001079 instrumentOneFunc(F, &M, BPI, BFI, ComdatMembers);
Rong Xuf430ae42015-12-09 18:08:16 +00001080 }
1081 return true;
1082}
1083
Xinliang David Li8aebf442016-05-06 05:49:19 +00001084bool PGOInstrumentationGenLegacyPass::runOnModule(Module &M) {
Xinliang David Li5ad7c822016-05-02 20:33:59 +00001085 if (skipModule(M))
1086 return false;
1087
Xinliang David Lidfa21c32016-05-09 21:37:12 +00001088 auto LookupBPI = [this](Function &F) {
1089 return &this->getAnalysis<BranchProbabilityInfoWrapperPass>(F).getBPI();
Xinliang David Li5ad7c822016-05-02 20:33:59 +00001090 };
Xinliang David Lidfa21c32016-05-09 21:37:12 +00001091 auto LookupBFI = [this](Function &F) {
1092 return &this->getAnalysis<BlockFrequencyInfoWrapperPass>(F).getBFI();
Xinliang David Li5ad7c822016-05-02 20:33:59 +00001093 };
1094 return InstrumentAllFunctions(M, LookupBPI, LookupBFI);
1095}
1096
Xinliang David Li8aebf442016-05-06 05:49:19 +00001097PreservedAnalyses PGOInstrumentationGen::run(Module &M,
Sean Silvafd03ac62016-08-09 00:28:38 +00001098 ModuleAnalysisManager &AM) {
Xinliang David Li8aebf442016-05-06 05:49:19 +00001099
1100 auto &FAM = AM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
Xinliang David Lidfa21c32016-05-09 21:37:12 +00001101 auto LookupBPI = [&FAM](Function &F) {
1102 return &FAM.getResult<BranchProbabilityAnalysis>(F);
Xinliang David Li8aebf442016-05-06 05:49:19 +00001103 };
1104
Xinliang David Lidfa21c32016-05-09 21:37:12 +00001105 auto LookupBFI = [&FAM](Function &F) {
1106 return &FAM.getResult<BlockFrequencyAnalysis>(F);
Xinliang David Li8aebf442016-05-06 05:49:19 +00001107 };
1108
1109 if (!InstrumentAllFunctions(M, LookupBPI, LookupBFI))
1110 return PreservedAnalyses::all();
1111
1112 return PreservedAnalyses::none();
1113}
1114
Xinliang David Lida195582016-05-10 21:59:52 +00001115static bool annotateAllFunctions(
1116 Module &M, StringRef ProfileFileName,
1117 function_ref<BranchProbabilityInfo *(Function &)> LookupBPI,
Xinliang David Lidfa21c32016-05-09 21:37:12 +00001118 function_ref<BlockFrequencyInfo *(Function &)> LookupBFI) {
Rong Xuf430ae42015-12-09 18:08:16 +00001119 DEBUG(dbgs() << "Read in profile counters: ");
1120 auto &Ctx = M.getContext();
1121 // Read the counter array from file.
1122 auto ReaderOrErr = IndexedInstrProfReader::create(ProfileFileName);
Vedant Kumar9152fd12016-05-19 03:54:45 +00001123 if (Error E = ReaderOrErr.takeError()) {
1124 handleAllErrors(std::move(E), [&](const ErrorInfoBase &EI) {
1125 Ctx.diagnose(
1126 DiagnosticInfoPGOProfile(ProfileFileName.data(), EI.message()));
1127 });
Rong Xuf430ae42015-12-09 18:08:16 +00001128 return false;
1129 }
1130
Xinliang David Lida195582016-05-10 21:59:52 +00001131 std::unique_ptr<IndexedInstrProfReader> PGOReader =
1132 std::move(ReaderOrErr.get());
Rong Xuf430ae42015-12-09 18:08:16 +00001133 if (!PGOReader) {
1134 Ctx.diagnose(DiagnosticInfoPGOProfile(ProfileFileName.data(),
Xinliang David Lida195582016-05-10 21:59:52 +00001135 StringRef("Cannot get PGOReader")));
Rong Xuf430ae42015-12-09 18:08:16 +00001136 return false;
1137 }
Rong Xu33c76c02016-02-10 17:18:30 +00001138 // TODO: might need to change the warning once the clang option is finalized.
1139 if (!PGOReader->isIRLevelProfile()) {
1140 Ctx.diagnose(DiagnosticInfoPGOProfile(
1141 ProfileFileName.data(), "Not an IR level instrumentation profile"));
1142 return false;
1143 }
1144
Rong Xu705f7772016-07-25 18:45:37 +00001145 std::unordered_multimap<Comdat *, GlobalValue *> ComdatMembers;
1146 collectComdatMembers(M, ComdatMembers);
Rong Xu6090afd2016-03-28 17:08:56 +00001147 std::vector<Function *> HotFunctions;
1148 std::vector<Function *> ColdFunctions;
Rong Xuf430ae42015-12-09 18:08:16 +00001149 for (auto &F : M) {
1150 if (F.isDeclaration())
1151 continue;
Xinliang David Lidfa21c32016-05-09 21:37:12 +00001152 auto *BPI = LookupBPI(F);
1153 auto *BFI = LookupBFI(F);
Rong Xu705f7772016-07-25 18:45:37 +00001154 PGOUseFunc Func(F, &M, ComdatMembers, BPI, BFI);
Sean Silva2e8f0952016-05-28 04:19:40 +00001155 if (!Func.readCounters(PGOReader.get()))
1156 continue;
1157 Func.populateCounters();
1158 Func.setBranchWeights();
1159 Func.annotateIndirectCallSites();
Sean Silva9dd4b5c2016-05-28 03:56:25 +00001160 PGOUseFunc::FuncFreqAttr FreqAttr = Func.getFuncFreqAttr();
1161 if (FreqAttr == PGOUseFunc::FFA_Cold)
Sean Silva2a730192016-05-28 03:02:50 +00001162 ColdFunctions.push_back(&F);
Sean Silva9dd4b5c2016-05-28 03:56:25 +00001163 else if (FreqAttr == PGOUseFunc::FFA_Hot)
1164 HotFunctions.push_back(&F);
Rong Xuf430ae42015-12-09 18:08:16 +00001165 }
Easwaran Raman8bceb9d2016-06-21 19:29:49 +00001166 M.setProfileSummary(PGOReader->getSummary().getMD(M.getContext()));
Rong Xu6090afd2016-03-28 17:08:56 +00001167 // Set function hotness attribute from the profile.
Sean Silva42cc3422016-05-28 04:24:39 +00001168 // We have to apply these attributes at the end because their presence
1169 // can affect the BranchProbabilityInfo of any callers, resulting in an
1170 // inconsistent MST between prof-gen and prof-use.
Rong Xu6090afd2016-03-28 17:08:56 +00001171 for (auto &F : HotFunctions) {
1172 F->addFnAttr(llvm::Attribute::InlineHint);
1173 DEBUG(dbgs() << "Set inline attribute to function: " << F->getName()
1174 << "\n");
1175 }
1176 for (auto &F : ColdFunctions) {
1177 F->addFnAttr(llvm::Attribute::Cold);
1178 DEBUG(dbgs() << "Set cold attribute to function: " << F->getName() << "\n");
1179 }
Rong Xuf430ae42015-12-09 18:08:16 +00001180 return true;
1181}
Xinliang David Lid55827f2016-05-07 05:39:12 +00001182
Xinliang David Lida195582016-05-10 21:59:52 +00001183PGOInstrumentationUse::PGOInstrumentationUse(std::string Filename)
Benjamin Kramer82de7d32016-05-27 14:27:24 +00001184 : ProfileFileName(std::move(Filename)) {
Xinliang David Lida195582016-05-10 21:59:52 +00001185 if (!PGOTestProfileFile.empty())
1186 ProfileFileName = PGOTestProfileFile;
1187}
1188
1189PreservedAnalyses PGOInstrumentationUse::run(Module &M,
Sean Silvafd03ac62016-08-09 00:28:38 +00001190 ModuleAnalysisManager &AM) {
Xinliang David Lida195582016-05-10 21:59:52 +00001191
1192 auto &FAM = AM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
1193 auto LookupBPI = [&FAM](Function &F) {
1194 return &FAM.getResult<BranchProbabilityAnalysis>(F);
1195 };
1196
1197 auto LookupBFI = [&FAM](Function &F) {
1198 return &FAM.getResult<BlockFrequencyAnalysis>(F);
1199 };
1200
1201 if (!annotateAllFunctions(M, ProfileFileName, LookupBPI, LookupBFI))
1202 return PreservedAnalyses::all();
1203
1204 return PreservedAnalyses::none();
1205}
1206
Xinliang David Lid55827f2016-05-07 05:39:12 +00001207bool PGOInstrumentationUseLegacyPass::runOnModule(Module &M) {
1208 if (skipModule(M))
1209 return false;
1210
Xinliang David Lidfa21c32016-05-09 21:37:12 +00001211 auto LookupBPI = [this](Function &F) {
1212 return &this->getAnalysis<BranchProbabilityInfoWrapperPass>(F).getBPI();
Xinliang David Lid55827f2016-05-07 05:39:12 +00001213 };
Xinliang David Lidfa21c32016-05-09 21:37:12 +00001214 auto LookupBFI = [this](Function &F) {
1215 return &this->getAnalysis<BlockFrequencyInfoWrapperPass>(F).getBFI();
Xinliang David Lid55827f2016-05-07 05:39:12 +00001216 };
1217
Xinliang David Lida195582016-05-10 21:59:52 +00001218 return annotateAllFunctions(M, ProfileFileName, LookupBPI, LookupBFI);
Xinliang David Lid55827f2016-05-07 05:39:12 +00001219}