Stephen Hines | 651f13c | 2014-04-23 16:59:28 -0700 | [diff] [blame] | 1 | //===--- CodeGenPGO.h - PGO Instrumentation for LLVM CodeGen ----*- C++ -*-===// |
| 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 | // Instrumentation-based profile-guided optimization |
| 11 | // |
| 12 | //===----------------------------------------------------------------------===// |
| 13 | |
Stephen Hines | 176edba | 2014-12-01 14:53:08 -0800 | [diff] [blame] | 14 | #ifndef LLVM_CLANG_LIB_CODEGEN_CODEGENPGO_H |
| 15 | #define LLVM_CLANG_LIB_CODEGEN_CODEGENPGO_H |
Stephen Hines | 651f13c | 2014-04-23 16:59:28 -0700 | [diff] [blame] | 16 | |
| 17 | #include "CGBuilder.h" |
| 18 | #include "CodeGenModule.h" |
| 19 | #include "CodeGenTypes.h" |
| 20 | #include "clang/Frontend/CodeGenOptions.h" |
| 21 | #include "llvm/ADT/StringMap.h" |
| 22 | #include "llvm/Support/MemoryBuffer.h" |
| 23 | #include <memory> |
| 24 | |
| 25 | namespace clang { |
| 26 | namespace CodeGen { |
| 27 | class RegionCounter; |
| 28 | |
Stephen Hines | 651f13c | 2014-04-23 16:59:28 -0700 | [diff] [blame] | 29 | /// Per-function PGO state. This class should generally not be used directly, |
| 30 | /// but instead through the CodeGenFunction and RegionCounter types. |
| 31 | class CodeGenPGO { |
| 32 | private: |
| 33 | CodeGenModule &CGM; |
| 34 | std::unique_ptr<std::string> PrefixedFuncName; |
| 35 | StringRef RawFuncName; |
| 36 | llvm::GlobalValue::LinkageTypes VarLinkage; |
| 37 | |
| 38 | unsigned NumRegionCounters; |
| 39 | uint64_t FunctionHash; |
| 40 | llvm::GlobalVariable *RegionCounters; |
| 41 | std::unique_ptr<llvm::DenseMap<const Stmt *, unsigned>> RegionCounterMap; |
| 42 | std::unique_ptr<llvm::DenseMap<const Stmt *, uint64_t>> StmtCountMap; |
| 43 | std::unique_ptr<std::vector<uint64_t>> RegionCounts; |
| 44 | uint64_t CurrentRegionCount; |
Stephen Hines | 176edba | 2014-12-01 14:53:08 -0800 | [diff] [blame] | 45 | std::string CoverageMapping; |
| 46 | /// \brief A flag that is set to true when this function doesn't need |
| 47 | /// to have coverage mapping data. |
| 48 | bool SkipCoverageMapping; |
Stephen Hines | 651f13c | 2014-04-23 16:59:28 -0700 | [diff] [blame] | 49 | |
| 50 | public: |
| 51 | CodeGenPGO(CodeGenModule &CGM) |
Stephen Hines | 6bcf27b | 2014-05-29 04:14:42 -0700 | [diff] [blame] | 52 | : CGM(CGM), NumRegionCounters(0), FunctionHash(0), |
Stephen Hines | 176edba | 2014-12-01 14:53:08 -0800 | [diff] [blame] | 53 | RegionCounters(nullptr), CurrentRegionCount(0), |
| 54 | SkipCoverageMapping(false) {} |
Stephen Hines | 651f13c | 2014-04-23 16:59:28 -0700 | [diff] [blame] | 55 | |
| 56 | /// Whether or not we have PGO region data for the current function. This is |
| 57 | /// false both when we have no data at all and when our data has been |
| 58 | /// discarded. |
Stephen Hines | 6bcf27b | 2014-05-29 04:14:42 -0700 | [diff] [blame] | 59 | bool haveRegionCounts() const { return RegionCounts != nullptr; } |
Stephen Hines | 651f13c | 2014-04-23 16:59:28 -0700 | [diff] [blame] | 60 | |
| 61 | /// Get the string used to identify this function in the profile data. |
| 62 | /// For functions with local linkage, this includes the main file name. |
| 63 | StringRef getFuncName() const { return StringRef(*PrefixedFuncName); } |
| 64 | std::string getFuncVarName(StringRef VarName) const { |
| 65 | return ("__llvm_profile_" + VarName + "_" + RawFuncName).str(); |
| 66 | } |
| 67 | |
| 68 | /// Return the counter value of the current region. |
| 69 | uint64_t getCurrentRegionCount() const { return CurrentRegionCount; } |
| 70 | |
| 71 | /// Set the counter value for the current region. This is used to keep track |
| 72 | /// of changes to the most recent counter from control flow and non-local |
| 73 | /// exits. |
| 74 | void setCurrentRegionCount(uint64_t Count) { CurrentRegionCount = Count; } |
| 75 | |
| 76 | /// Indicate that the current region is never reached, and thus should have a |
| 77 | /// counter value of zero. This is important so that subsequent regions can |
| 78 | /// correctly track their parent counts. |
| 79 | void setCurrentRegionUnreachable() { setCurrentRegionCount(0); } |
| 80 | |
| 81 | /// Check if an execution count is known for a given statement. If so, return |
| 82 | /// true and put the value in Count; else return false. |
| 83 | bool getStmtCount(const Stmt *S, uint64_t &Count) { |
| 84 | if (!StmtCountMap) |
| 85 | return false; |
| 86 | llvm::DenseMap<const Stmt*, uint64_t>::const_iterator |
| 87 | I = StmtCountMap->find(S); |
| 88 | if (I == StmtCountMap->end()) |
| 89 | return false; |
| 90 | Count = I->second; |
| 91 | return true; |
| 92 | } |
| 93 | |
| 94 | /// If the execution count for the current statement is known, record that |
| 95 | /// as the current count. |
| 96 | void setCurrentStmt(const Stmt *S) { |
| 97 | uint64_t Count; |
| 98 | if (getStmtCount(S, Count)) |
| 99 | setCurrentRegionCount(Count); |
| 100 | } |
| 101 | |
| 102 | /// Calculate branch weights appropriate for PGO data |
| 103 | llvm::MDNode *createBranchWeights(uint64_t TrueCount, uint64_t FalseCount); |
| 104 | llvm::MDNode *createBranchWeights(ArrayRef<uint64_t> Weights); |
| 105 | llvm::MDNode *createLoopWeights(const Stmt *Cond, RegionCounter &Cnt); |
| 106 | |
Stephen Hines | 176edba | 2014-12-01 14:53:08 -0800 | [diff] [blame] | 107 | /// Check if we need to emit coverage mapping for a given declaration |
| 108 | void checkGlobalDecl(GlobalDecl GD); |
Stephen Hines | 651f13c | 2014-04-23 16:59:28 -0700 | [diff] [blame] | 109 | /// Assign counters to regions and configure them for PGO of a given |
| 110 | /// function. Does nothing if instrumentation is not enabled and either |
| 111 | /// generates global variables or associates PGO data with each of the |
| 112 | /// counters depending on whether we are generating or using instrumentation. |
| 113 | void assignRegionCounters(const Decl *D, llvm::Function *Fn); |
| 114 | /// Emit static data structures for instrumentation data. |
| 115 | void emitInstrumentationData(); |
| 116 | /// Clean up region counter state. Must be called if assignRegionCounters is |
| 117 | /// used. |
| 118 | void destroyRegionCounters(); |
| 119 | /// Emit static initialization code, if any. |
| 120 | static llvm::Function *emitInitialization(CodeGenModule &CGM); |
Stephen Hines | 176edba | 2014-12-01 14:53:08 -0800 | [diff] [blame] | 121 | /// Emit a coverage mapping range with a counter zero |
| 122 | /// for an unused declaration. |
| 123 | void emitEmptyCounterMapping(const Decl *D, StringRef FuncName, |
| 124 | llvm::GlobalValue::LinkageTypes Linkage); |
Stephen Hines | 651f13c | 2014-04-23 16:59:28 -0700 | [diff] [blame] | 125 | private: |
| 126 | void setFuncName(llvm::Function *Fn); |
Stephen Hines | 176edba | 2014-12-01 14:53:08 -0800 | [diff] [blame] | 127 | void setFuncName(StringRef Name, llvm::GlobalValue::LinkageTypes Linkage); |
| 128 | void setVarLinkage(llvm::GlobalValue::LinkageTypes Linkage); |
Stephen Hines | 651f13c | 2014-04-23 16:59:28 -0700 | [diff] [blame] | 129 | void mapRegionCounters(const Decl *D); |
| 130 | void computeRegionCounts(const Decl *D); |
Stephen Hines | 6bcf27b | 2014-05-29 04:14:42 -0700 | [diff] [blame] | 131 | void applyFunctionAttributes(llvm::IndexedInstrProfReader *PGOReader, |
| 132 | llvm::Function *Fn); |
Stephen Hines | c568f1e | 2014-07-21 00:47:37 -0700 | [diff] [blame] | 133 | void loadRegionCounts(llvm::IndexedInstrProfReader *PGOReader, |
| 134 | bool IsInMainFile); |
Stephen Hines | 651f13c | 2014-04-23 16:59:28 -0700 | [diff] [blame] | 135 | void emitCounterVariables(); |
| 136 | llvm::GlobalVariable *buildDataVar(); |
Stephen Hines | 176edba | 2014-12-01 14:53:08 -0800 | [diff] [blame] | 137 | void emitCounterRegionMapping(const Decl *D); |
Stephen Hines | 651f13c | 2014-04-23 16:59:28 -0700 | [diff] [blame] | 138 | |
| 139 | /// Emit code to increment the counter at the given index |
| 140 | void emitCounterIncrement(CGBuilderTy &Builder, unsigned Counter); |
| 141 | |
| 142 | /// Return the region counter for the given statement. This should only be |
| 143 | /// called on statements that have a dedicated counter. |
| 144 | unsigned getRegionCounter(const Stmt *S) { |
Stephen Hines | 6bcf27b | 2014-05-29 04:14:42 -0700 | [diff] [blame] | 145 | if (!RegionCounterMap) |
Stephen Hines | 651f13c | 2014-04-23 16:59:28 -0700 | [diff] [blame] | 146 | return 0; |
| 147 | return (*RegionCounterMap)[S]; |
| 148 | } |
| 149 | |
| 150 | /// Return the region count for the counter at the given index. |
| 151 | uint64_t getRegionCount(unsigned Counter) { |
| 152 | if (!haveRegionCounts()) |
| 153 | return 0; |
| 154 | return (*RegionCounts)[Counter]; |
| 155 | } |
| 156 | |
| 157 | friend class RegionCounter; |
| 158 | }; |
| 159 | |
| 160 | /// A counter for a particular region. This is the primary interface through |
| 161 | /// which clients manage PGO counters and their values. |
| 162 | class RegionCounter { |
| 163 | CodeGenPGO *PGO; |
| 164 | unsigned Counter; |
| 165 | uint64_t Count; |
| 166 | uint64_t ParentCount; |
| 167 | uint64_t RegionCount; |
| 168 | int64_t Adjust; |
| 169 | |
| 170 | RegionCounter(CodeGenPGO &PGO, unsigned CounterIndex) |
| 171 | : PGO(&PGO), Counter(CounterIndex), Count(PGO.getRegionCount(Counter)), |
| 172 | ParentCount(PGO.getCurrentRegionCount()), Adjust(0) {} |
| 173 | |
| 174 | public: |
| 175 | RegionCounter(CodeGenPGO &PGO, const Stmt *S) |
| 176 | : PGO(&PGO), Counter(PGO.getRegionCounter(S)), |
| 177 | Count(PGO.getRegionCount(Counter)), |
| 178 | ParentCount(PGO.getCurrentRegionCount()), Adjust(0) {} |
| 179 | |
| 180 | /// Get the value of the counter. In most cases this is the number of times |
| 181 | /// the region of the counter was entered, but for switch labels it's the |
| 182 | /// number of direct jumps to that label. |
| 183 | uint64_t getCount() const { return Count; } |
| 184 | |
| 185 | /// Get the value of the counter with adjustments applied. Adjustments occur |
| 186 | /// when control enters or leaves the region abnormally; i.e., if there is a |
| 187 | /// jump to a label within the region, or if the function can return from |
| 188 | /// within the region. The adjusted count, then, is the value of the counter |
| 189 | /// at the end of the region. |
| 190 | uint64_t getAdjustedCount() const { |
| 191 | return Count + Adjust; |
| 192 | } |
| 193 | |
| 194 | /// Get the value of the counter in this region's parent, i.e., the region |
| 195 | /// that was active when this region began. This is useful for deriving |
| 196 | /// counts in implicitly counted regions, like the false case of a condition |
| 197 | /// or the normal exits of a loop. |
| 198 | uint64_t getParentCount() const { return ParentCount; } |
| 199 | |
| 200 | /// Activate the counter by emitting an increment and starting to track |
| 201 | /// adjustments. If AddIncomingFallThrough is true, the current region count |
| 202 | /// will be added to the counter for the purposes of tracking the region. |
| 203 | void beginRegion(CGBuilderTy &Builder, bool AddIncomingFallThrough=false) { |
| 204 | beginRegion(AddIncomingFallThrough); |
| 205 | PGO->emitCounterIncrement(Builder, Counter); |
| 206 | } |
| 207 | void beginRegion(bool AddIncomingFallThrough=false) { |
| 208 | RegionCount = Count; |
| 209 | if (AddIncomingFallThrough) |
| 210 | RegionCount += PGO->getCurrentRegionCount(); |
| 211 | PGO->setCurrentRegionCount(RegionCount); |
| 212 | } |
| 213 | |
| 214 | /// For counters on boolean branches, begins tracking adjustments for the |
| 215 | /// uncounted path. |
| 216 | void beginElseRegion() { |
| 217 | RegionCount = ParentCount - Count; |
| 218 | PGO->setCurrentRegionCount(RegionCount); |
| 219 | } |
| 220 | |
| 221 | /// Reset the current region count. |
| 222 | void setCurrentRegionCount(uint64_t CurrentCount) { |
| 223 | RegionCount = CurrentCount; |
| 224 | PGO->setCurrentRegionCount(RegionCount); |
| 225 | } |
| 226 | |
| 227 | /// Adjust for non-local control flow after emitting a subexpression or |
| 228 | /// substatement. This must be called to account for constructs such as gotos, |
| 229 | /// labels, and returns, so that we can ensure that our region's count is |
| 230 | /// correct in the code that follows. |
| 231 | void adjustForControlFlow() { |
| 232 | Adjust += PGO->getCurrentRegionCount() - RegionCount; |
| 233 | // Reset the region count in case this is called again later. |
| 234 | RegionCount = PGO->getCurrentRegionCount(); |
| 235 | } |
| 236 | |
| 237 | /// Commit all adjustments to the current region. If the region is a loop, |
| 238 | /// the LoopAdjust value should be the count of all the breaks and continues |
| 239 | /// from the loop, to compensate for those counts being deducted from the |
| 240 | /// adjustments for the body of the loop. |
| 241 | void applyAdjustmentsToRegion(uint64_t LoopAdjust) { |
| 242 | PGO->setCurrentRegionCount(ParentCount + Adjust + LoopAdjust); |
| 243 | } |
| 244 | }; |
| 245 | |
| 246 | } // end namespace CodeGen |
| 247 | } // end namespace clang |
| 248 | |
| 249 | #endif |