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 ModulePass; 32 class OptimizationRemarkEmitter; 33 class Comdat; 34 class CallBase; 35 36 /// Instrumentation passes often insert conditional checks into entry blocks. 37 /// Call this function before splitting the entry block to move instructions 38 /// that must remain in the entry block up before the split point. Static 39 /// allocas and llvm.localescape calls, for example, must remain in the entry 40 /// block. 41 BasicBlock::iterator PrepareToSplitEntryBlock(BasicBlock &BB, 42 BasicBlock::iterator IP); 43 44 // Create a constant for Str so that we can pass it to the run-time lib. 45 GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str, 46 bool AllowMerging, 47 const char *NamePrefix = ""); 48 49 // Returns F.getComdat() if it exists. 50 // Otherwise creates a new comdat, sets F's comdat, and returns it. 51 // Returns nullptr on failure. 52 Comdat *getOrCreateFunctionComdat(Function &F, Triple &T); 53 54 // Insert GCOV profiling instrumentation 55 struct GCOVOptions { 56 static GCOVOptions getDefault(); 57 58 // Specify whether to emit .gcno files. 59 bool EmitNotes; 60 61 // Specify whether to modify the program to emit .gcda files when run. 62 bool EmitData; 63 64 // A four-byte version string. The meaning of a version string is described in 65 // gcc's gcov-io.h 66 char Version[4]; 67 68 // Add the 'noredzone' attribute to added runtime library calls. 69 bool NoRedZone; 70 71 // Use atomic profile counter increments. 72 bool Atomic = false; 73 74 // Regexes separated by a semi-colon to filter the files to instrument. 75 std::string Filter; 76 77 // Regexes separated by a semi-colon to filter the files to not instrument. 78 std::string Exclude; 79 }; 80 81 // The pgo-specific indirect call promotion function declared below is used by 82 // the pgo-driven indirect call promotion and sample profile passes. It's a 83 // wrapper around llvm::promoteCall, et al. that additionally computes !prof 84 // metadata. We place it in a pgo namespace so it's not confused with the 85 // generic utilities. 86 namespace pgo { 87 88 // Helper function that transforms CB (either an indirect-call instruction, or 89 // an invoke instruction , to a conditional call to F. This is like: 90 // if (Inst.CalledValue == F) 91 // F(...); 92 // else 93 // Inst(...); 94 // end 95 // TotalCount is the profile count value that the instruction executes. 96 // Count is the profile count value that F is the target function. 97 // These two values are used to update the branch weight. 98 // If \p AttachProfToDirectCall is true, a prof metadata is attached to the 99 // new direct call to contain \p Count. 100 // Returns the promoted direct call instruction. 101 CallBase &promoteIndirectCall(CallBase &CB, Function *F, uint64_t Count, 102 uint64_t TotalCount, bool AttachProfToDirectCall, 103 OptimizationRemarkEmitter *ORE); 104 } // namespace pgo 105 106 /// Options for the frontend instrumentation based profiling pass. 107 struct InstrProfOptions { 108 // Add the 'noredzone' attribute to added runtime library calls. 109 bool NoRedZone = false; 110 111 // Do counter register promotion 112 bool DoCounterPromotion = false; 113 114 // Use atomic profile counter increments. 115 bool Atomic = false; 116 117 // Use BFI to guide register promotion 118 bool UseBFIInPromotion = false; 119 120 // Name of the profile file to use as output 121 std::string InstrProfileOutput; 122 123 InstrProfOptions() = default; 124 }; 125 126 // Insert DataFlowSanitizer (dynamic data flow analysis) instrumentation 127 ModulePass *createDataFlowSanitizerLegacyPassPass( 128 const std::vector<std::string> &ABIListFiles = std::vector<std::string>()); 129 130 // Options for sanitizer coverage instrumentation. 131 struct SanitizerCoverageOptions { 132 enum Type { 133 SCK_None = 0, 134 SCK_Function, 135 SCK_BB, 136 SCK_Edge 137 } CoverageType = SCK_None; 138 bool IndirectCalls = false; 139 bool TraceBB = false; 140 bool TraceCmp = false; 141 bool TraceDiv = false; 142 bool TraceGep = false; 143 bool Use8bitCounters = false; 144 bool TracePC = false; 145 bool TracePCGuard = false; 146 bool Inline8bitCounters = false; 147 bool InlineBoolFlag = false; 148 bool PCTable = false; 149 bool NoPrune = false; 150 bool StackDepth = false; 151 bool TraceLoads = false; 152 bool TraceStores = false; 153 154 SanitizerCoverageOptions() = default; 155 }; 156 157 /// Calculate what to divide by to scale counts. 158 /// 159 /// Given the maximum count, calculate a divisor that will scale all the 160 /// weights to strictly less than std::numeric_limits<uint32_t>::max(). 161 static inline uint64_t calculateCountScale(uint64_t MaxCount) { 162 return MaxCount < std::numeric_limits<uint32_t>::max() 163 ? 1 164 : MaxCount / std::numeric_limits<uint32_t>::max() + 1; 165 } 166 167 /// Scale an individual branch count. 168 /// 169 /// Scale a 64-bit weight down to 32-bits using \c Scale. 170 /// 171 static inline uint32_t scaleBranchCount(uint64_t Count, uint64_t Scale) { 172 uint64_t Scaled = Count / Scale; 173 assert(Scaled <= std::numeric_limits<uint32_t>::max() && "overflow 32-bits"); 174 return Scaled; 175 } 176 177 // Use to ensure the inserted instrumentation has a DebugLocation; if none is 178 // attached to the source instruction, try to use a DILocation with offset 0 179 // scoped to surrounding function (if it has a DebugLocation). 180 // 181 // Some non-call instructions may be missing debug info, but when inserting 182 // instrumentation calls, some builds (e.g. LTO) want calls to have debug info 183 // if the enclosing function does. 184 struct InstrumentationIRBuilder : IRBuilder<> { 185 static void ensureDebugInfo(IRBuilder<> &IRB, const Function &F) { 186 if (IRB.getCurrentDebugLocation()) 187 return; 188 if (DISubprogram *SP = F.getSubprogram()) 189 IRB.SetCurrentDebugLocation(DILocation::get(SP->getContext(), 0, 0, SP)); 190 } 191 192 explicit InstrumentationIRBuilder(Instruction *IP) : IRBuilder<>(IP) { 193 ensureDebugInfo(*this, *IP->getFunction()); 194 } 195 }; 196 } // end namespace llvm 197 198 #endif // LLVM_TRANSFORMS_INSTRUMENTATION_H 199