1 //===- Transforms/Instrumentation.h - Instrumentation passes ----*- 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 // This file defines constructor functions for instrumentation passes. 10 // 11 //===----------------------------------------------------------------------===// 12 13 #ifndef LLVM_TRANSFORMS_INSTRUMENTATION_H 14 #define LLVM_TRANSFORMS_INSTRUMENTATION_H 15 16 #include "llvm/ADT/StringRef.h" 17 #include "llvm/IR/BasicBlock.h" 18 #include "llvm/IR/DebugInfoMetadata.h" 19 #include "llvm/IR/Function.h" 20 #include "llvm/IR/IRBuilder.h" 21 #include "llvm/IR/Instruction.h" 22 #include <cassert> 23 #include <cstdint> 24 #include <limits> 25 #include <string> 26 #include <vector> 27 28 namespace llvm { 29 30 class Triple; 31 class OptimizationRemarkEmitter; 32 class Comdat; 33 class CallBase; 34 35 /// Instrumentation passes often insert conditional checks into entry blocks. 36 /// Call this function before splitting the entry block to move instructions 37 /// that must remain in the entry block up before the split point. Static 38 /// allocas and llvm.localescape calls, for example, must remain in the entry 39 /// block. 40 BasicBlock::iterator PrepareToSplitEntryBlock(BasicBlock &BB, 41 BasicBlock::iterator IP); 42 43 // Create a constant for Str so that we can pass it to the run-time lib. 44 GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str, 45 bool AllowMerging, 46 const char *NamePrefix = ""); 47 48 // Returns F.getComdat() if it exists. 49 // Otherwise creates a new comdat, sets F's comdat, and returns it. 50 // Returns nullptr on failure. 51 Comdat *getOrCreateFunctionComdat(Function &F, Triple &T); 52 53 // Insert GCOV profiling instrumentation 54 struct GCOVOptions { 55 static GCOVOptions getDefault(); 56 57 // Specify whether to emit .gcno files. 58 bool EmitNotes; 59 60 // Specify whether to modify the program to emit .gcda files when run. 61 bool EmitData; 62 63 // A four-byte version string. The meaning of a version string is described in 64 // gcc's gcov-io.h 65 char Version[4]; 66 67 // Add the 'noredzone' attribute to added runtime library calls. 68 bool NoRedZone; 69 70 // Use atomic profile counter increments. 71 bool Atomic = false; 72 73 // Regexes separated by a semi-colon to filter the files to instrument. 74 std::string Filter; 75 76 // Regexes separated by a semi-colon to filter the files to not instrument. 77 std::string Exclude; 78 }; 79 80 // The pgo-specific indirect call promotion function declared below is used by 81 // the pgo-driven indirect call promotion and sample profile passes. It's a 82 // wrapper around llvm::promoteCall, et al. that additionally computes !prof 83 // metadata. We place it in a pgo namespace so it's not confused with the 84 // generic utilities. 85 namespace pgo { 86 87 // Helper function that transforms CB (either an indirect-call instruction, or 88 // an invoke instruction , to a conditional call to F. This is like: 89 // if (Inst.CalledValue == F) 90 // F(...); 91 // else 92 // Inst(...); 93 // end 94 // TotalCount is the profile count value that the instruction executes. 95 // Count is the profile count value that F is the target function. 96 // These two values are used to update the branch weight. 97 // If \p AttachProfToDirectCall is true, a prof metadata is attached to the 98 // new direct call to contain \p Count. 99 // Returns the promoted direct call instruction. 100 CallBase &promoteIndirectCall(CallBase &CB, Function *F, uint64_t Count, 101 uint64_t TotalCount, bool AttachProfToDirectCall, 102 OptimizationRemarkEmitter *ORE); 103 } // namespace pgo 104 105 /// Options for the frontend instrumentation based profiling pass. 106 struct InstrProfOptions { 107 // Add the 'noredzone' attribute to added runtime library calls. 108 bool NoRedZone = false; 109 110 // Do counter register promotion 111 bool DoCounterPromotion = false; 112 113 // Use atomic profile counter increments. 114 bool Atomic = false; 115 116 // Use BFI to guide register promotion 117 bool UseBFIInPromotion = false; 118 119 // Name of the profile file to use as output 120 std::string InstrProfileOutput; 121 122 InstrProfOptions() = default; 123 }; 124 125 // Options for sanitizer coverage instrumentation. 126 struct SanitizerCoverageOptions { 127 enum Type { 128 SCK_None = 0, 129 SCK_Function, 130 SCK_BB, 131 SCK_Edge 132 } CoverageType = SCK_None; 133 bool IndirectCalls = false; 134 bool TraceBB = false; 135 bool TraceCmp = false; 136 bool TraceDiv = false; 137 bool TraceGep = false; 138 bool Use8bitCounters = false; 139 bool TracePC = false; 140 bool TracePCGuard = false; 141 bool Inline8bitCounters = false; 142 bool InlineBoolFlag = false; 143 bool PCTable = false; 144 bool NoPrune = false; 145 bool StackDepth = false; 146 bool TraceLoads = false; 147 bool TraceStores = false; 148 bool CollectControlFlow = false; 149 150 SanitizerCoverageOptions() = default; 151 }; 152 153 /// Calculate what to divide by to scale counts. 154 /// 155 /// Given the maximum count, calculate a divisor that will scale all the 156 /// weights to strictly less than std::numeric_limits<uint32_t>::max(). 157 static inline uint64_t calculateCountScale(uint64_t MaxCount) { 158 return MaxCount < std::numeric_limits<uint32_t>::max() 159 ? 1 160 : MaxCount / std::numeric_limits<uint32_t>::max() + 1; 161 } 162 163 /// Scale an individual branch count. 164 /// 165 /// Scale a 64-bit weight down to 32-bits using \c Scale. 166 /// 167 static inline uint32_t scaleBranchCount(uint64_t Count, uint64_t Scale) { 168 uint64_t Scaled = Count / Scale; 169 assert(Scaled <= std::numeric_limits<uint32_t>::max() && "overflow 32-bits"); 170 return Scaled; 171 } 172 173 // Use to ensure the inserted instrumentation has a DebugLocation; if none is 174 // attached to the source instruction, try to use a DILocation with offset 0 175 // scoped to surrounding function (if it has a DebugLocation). 176 // 177 // Some non-call instructions may be missing debug info, but when inserting 178 // instrumentation calls, some builds (e.g. LTO) want calls to have debug info 179 // if the enclosing function does. 180 struct InstrumentationIRBuilder : IRBuilder<> { 181 static void ensureDebugInfo(IRBuilder<> &IRB, const Function &F) { 182 if (IRB.getCurrentDebugLocation()) 183 return; 184 if (DISubprogram *SP = F.getSubprogram()) 185 IRB.SetCurrentDebugLocation(DILocation::get(SP->getContext(), 0, 0, SP)); 186 } 187 188 explicit InstrumentationIRBuilder(Instruction *IP) : IRBuilder<>(IP) { 189 ensureDebugInfo(*this, *IP->getFunction()); 190 } 191 }; 192 } // end namespace llvm 193 194 #endif // LLVM_TRANSFORMS_INSTRUMENTATION_H 195