clang/lib/CodeGen/CodeGenPGO.h

   1 //===--- CodeGenPGO.h - PGO Instrumentation for LLVM CodeGen ----*- C++ -*-===//
   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 // Instrumentation-based profile-guided optimization
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #ifndef LLVM_CLANG_LIB_CODEGEN_CODEGENPGO_H
  14 #define LLVM_CLANG_LIB_CODEGEN_CODEGENPGO_H
  15
  16 #include "CGBuilder.h"
  17 #include "CodeGenModule.h"
  18 #include "CodeGenTypes.h"
  19 #include "MCDCState.h"
  20 #include "llvm/ProfileData/InstrProfReader.h"
  21 #include <array>
  22 #include <memory>
  23 #include <optional>
  24
  25 namespace clang {
  26 namespace CodeGen {
  27
  28 /// Per-function PGO state.
  29 class CodeGenPGO {
  30 private:
  31   CodeGenModule &CGM;
  32   std::string FuncName;
  33   llvm::GlobalVariable *FuncNameVar;
  34
  35   std::array <unsigned, llvm::IPVK_Last + 1> NumValueSites;
  36   unsigned NumRegionCounters;
  37   uint64_t FunctionHash;
  38   std::unique_ptr<llvm::DenseMap<const Stmt *, unsigned>> RegionCounterMap;
  39   std::unique_ptr<llvm::DenseMap<const Stmt *, uint64_t>> StmtCountMap;
  40   std::unique_ptr<llvm::InstrProfRecord> ProfRecord;
  41   std::unique_ptr<MCDC::State> RegionMCDCState;
  42   std::vector<uint64_t> RegionCounts;
  43   uint64_t CurrentRegionCount;
  44
  45 public:
  46   CodeGenPGO(CodeGenModule &CGModule)
  47       : CGM(CGModule), FuncNameVar(nullptr), NumValueSites({{0}}),
  48         NumRegionCounters(0), FunctionHash(0), CurrentRegionCount(0) {}
  49
  50   /// Whether or not we have PGO region data for the current function. This is
  51   /// false both when we have no data at all and when our data has been
  52   /// discarded.
  53   bool haveRegionCounts() const { return !RegionCounts.empty(); }
  54
  55   /// Return the counter value of the current region.
  56   uint64_t getCurrentRegionCount() const { return CurrentRegionCount; }
  57
  58   /// Set the counter value for the current region. This is used to keep track
  59   /// of changes to the most recent counter from control flow and non-local
  60   /// exits.
  61   void setCurrentRegionCount(uint64_t Count) { CurrentRegionCount = Count; }
  62
  63   /// Check if an execution count is known for a given statement. If so, return
  64   /// true and put the value in Count; else return false.
  65   std::optional<uint64_t> getStmtCount(const Stmt *S) const {
  66     if (!StmtCountMap)
  67       return std::nullopt;
  68     auto I = StmtCountMap->find(S);
  69     if (I == StmtCountMap->end())
  70       return std::nullopt;
  71     return I->second;
  72   }
  73
  74   /// If the execution count for the current statement is known, record that
  75   /// as the current count.
  76   void setCurrentStmt(const Stmt *S) {
  77     if (auto Count = getStmtCount(S))
  78       setCurrentRegionCount(*Count);
  79   }
  80
  81   /// Assign counters to regions and configure them for PGO of a given
  82   /// function. Does nothing if instrumentation is not enabled and either
  83   /// generates global variables or associates PGO data with each of the
  84   /// counters depending on whether we are generating or using instrumentation.
  85   void assignRegionCounters(GlobalDecl GD, llvm::Function *Fn);
  86   /// Emit a coverage mapping range with a counter zero
  87   /// for an unused declaration.
  88   void emitEmptyCounterMapping(const Decl *D, StringRef FuncName,
  89                                llvm::GlobalValue::LinkageTypes Linkage);
  90   // Insert instrumentation or attach profile metadata at value sites
  91   void valueProfile(CGBuilderTy &Builder, uint32_t ValueKind,
  92                     llvm::Instruction *ValueSite, llvm::Value *ValuePtr);
  93
  94   // Set a module flag indicating if value profiling is enabled.
  95   void setValueProfilingFlag(llvm::Module &M);
  96
  97   void setProfileVersion(llvm::Module &M);
  98
  99 private:
 100   void setFuncName(llvm::Function *Fn);
 101   void setFuncName(StringRef Name, llvm::GlobalValue::LinkageTypes Linkage);
 102   void mapRegionCounters(const Decl *D);
 103   void computeRegionCounts(const Decl *D);
 104   void applyFunctionAttributes(llvm::IndexedInstrProfReader *PGOReader,
 105                                llvm::Function *Fn);
 106   void loadRegionCounts(llvm::IndexedInstrProfReader *PGOReader,
 107                         bool IsInMainFile);
 108   bool skipRegionMappingForDecl(const Decl *D);
 109   void emitCounterRegionMapping(const Decl *D);
 110   bool canEmitMCDCCoverage(const CGBuilderTy &Builder);
 111
 112 public:
 113   void emitCounterSetOrIncrement(CGBuilderTy &Builder, const Stmt *S,
 114                                  llvm::Value *StepV);
 115   void emitMCDCTestVectorBitmapUpdate(CGBuilderTy &Builder, const Expr *S,
 116                                       Address MCDCCondBitmapAddr,
 117                                       CodeGenFunction &CGF);
 118   void emitMCDCParameters(CGBuilderTy &Builder);
 119   void emitMCDCCondBitmapReset(CGBuilderTy &Builder, const Expr *S,
 120                                Address MCDCCondBitmapAddr);
 121   void emitMCDCCondBitmapUpdate(CGBuilderTy &Builder, const Expr *S,
 122                                 Address MCDCCondBitmapAddr, llvm::Value *Val,
 123                                 CodeGenFunction &CGF);
 124
 125   /// Return the region count for the counter at the given index.
 126   uint64_t getRegionCount(const Stmt *S) {
 127     if (!RegionCounterMap)
 128       return 0;
 129     if (!haveRegionCounts())
 130       return 0;
 131     // With profiles from a differing version of clang we can have mismatched
 132     // decl counts. Don't crash in such a case.
 133     auto Index = (*RegionCounterMap)[S];
 134     if (Index >= RegionCounts.size())
 135       return 0;
 136     return RegionCounts[Index];
 137   }
 138 };
 139
 140 }  // end namespace CodeGen
 141 }  // end namespace clang
 142
 143 #endif