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//===--- CodeGenPGO.h - PGO Instrumentation for LLVM CodeGen ----*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// Instrumentation-based profile-guided optimization
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_CLANG_LIB_CODEGEN_CODEGENPGO_H
#define LLVM_CLANG_LIB_CODEGEN_CODEGENPGO_H
#include "CGBuilder.h"
#include "CodeGenModule.h"
#include "CodeGenTypes.h"
#include "llvm/ProfileData/InstrProfReader.h"
#include <array>
#include <memory>
namespace clang {
namespace CodeGen {
/// Per-function PGO state.
class CodeGenPGO {
private:
CodeGenModule &CGM;
std::string FuncName;
llvm::GlobalVariable *FuncNameVar;
std::array <unsigned, llvm::IPVK_Last + 1> NumValueSites;
unsigned NumRegionCounters;
uint64_t FunctionHash;
std::unique_ptr<llvm::DenseMap<const Stmt *, unsigned>> RegionCounterMap;
std::unique_ptr<llvm::DenseMap<const Stmt *, uint64_t>> StmtCountMap;
std::unique_ptr<llvm::InstrProfRecord> ProfRecord;
std::vector<uint64_t> RegionCounts;
uint64_t CurrentRegionCount;
public:
CodeGenPGO(CodeGenModule &CGModule)
: CGM(CGModule), FuncNameVar(nullptr), NumValueSites({{0}}),
NumRegionCounters(0), FunctionHash(0), CurrentRegionCount(0) {}
/// Whether or not we have PGO region data for the current function. This is
/// false both when we have no data at all and when our data has been
/// discarded.
bool haveRegionCounts() const { return !RegionCounts.empty(); }
/// Return the counter value of the current region.
uint64_t getCurrentRegionCount() const { return CurrentRegionCount; }
/// Set the counter value for the current region. This is used to keep track
/// of changes to the most recent counter from control flow and non-local
/// exits.
void setCurrentRegionCount(uint64_t Count) { CurrentRegionCount = Count; }
/// Check if an execution count is known for a given statement. If so, return
/// true and put the value in Count; else return false.
Optional<uint64_t> getStmtCount(const Stmt *S) const {
if (!StmtCountMap)
return None;
auto I = StmtCountMap->find(S);
if (I == StmtCountMap->end())
return None;
return I->second;
}
/// If the execution count for the current statement is known, record that
/// as the current count.
void setCurrentStmt(const Stmt *S) {
if (auto Count = getStmtCount(S))
setCurrentRegionCount(*Count);
}
/// Assign counters to regions and configure them for PGO of a given
/// function. Does nothing if instrumentation is not enabled and either
/// generates global variables or associates PGO data with each of the
/// counters depending on whether we are generating or using instrumentation.
void assignRegionCounters(GlobalDecl GD, llvm::Function *Fn);
/// Emit a coverage mapping range with a counter zero
/// for an unused declaration.
void emitEmptyCounterMapping(const Decl *D, StringRef FuncName,
llvm::GlobalValue::LinkageTypes Linkage);
// Insert instrumentation or attach profile metadata at value sites
void valueProfile(CGBuilderTy &Builder, uint32_t ValueKind,
llvm::Instruction *ValueSite, llvm::Value *ValuePtr);
// Set a module flag indicating if value profiling is enabled.
void setValueProfilingFlag(llvm::Module &M);
private:
void setFuncName(llvm::Function *Fn);
void setFuncName(StringRef Name, llvm::GlobalValue::LinkageTypes Linkage);
void mapRegionCounters(const Decl *D);
void computeRegionCounts(const Decl *D);
void applyFunctionAttributes(llvm::IndexedInstrProfReader *PGOReader,
llvm::Function *Fn);
void loadRegionCounts(llvm::IndexedInstrProfReader *PGOReader,
bool IsInMainFile);
bool skipRegionMappingForDecl(const Decl *D);
void emitCounterRegionMapping(const Decl *D);
public:
void emitCounterIncrement(CGBuilderTy &Builder, const Stmt *S,
llvm::Value *StepV);
/// Return the region count for the counter at the given index.
uint64_t getRegionCount(const Stmt *S) {
if (!RegionCounterMap)
return 0;
if (!haveRegionCounts())
return 0;
return RegionCounts[(*RegionCounterMap)[S]];
}
};
} // end namespace CodeGen
} // end namespace clang
#endif
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