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 "llvm/Support/Compiler.h"
23 #include <cassert>
24 #include <cstdint>
25 #include <limits>
26 #include <string>
27
28 namespace llvm {
29
30 class Triple;
31 class OptimizationRemarkEmitter;
32 class Comdat;
33 class CallBase;
34 class Module;
35
36 /// Check if module has flag attached, if not add the flag.
37 LLVM_ABI bool checkIfAlreadyInstrumented(Module &M, StringRef Flag);
38
39 /// Instrumentation passes often insert conditional checks into entry blocks.
40 /// Call this function before splitting the entry block to move instructions
41 /// that must remain in the entry block up before the split point. Static
42 /// allocas and llvm.localescape calls, for example, must remain in the entry
43 /// block.
44 LLVM_ABI BasicBlock::iterator PrepareToSplitEntryBlock(BasicBlock &BB,
45 BasicBlock::iterator IP);
46
47 // Create a constant for Str so that we can pass it to the run-time lib.
48 LLVM_ABI GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str,
49 bool AllowMerging,
50 Twine NamePrefix = "");
51
52 // Returns F.getComdat() if it exists.
53 // Otherwise creates a new comdat, sets F's comdat, and returns it.
54 // Returns nullptr on failure.
55 LLVM_ABI Comdat *getOrCreateFunctionComdat(Function &F, Triple &T);
56
57 // Place global in a large section for x86-64 ELF binaries to mitigate
58 // relocation overflow pressure. This can be be used for metadata globals that
59 // aren't directly accessed by code, which has no performance impact.
60 LLVM_ABI void setGlobalVariableLargeSection(const Triple &TargetTriple,
61 GlobalVariable &GV);
62
63 // Insert GCOV profiling instrumentation
64 struct GCOVOptions {
65 LLVM_ABI static GCOVOptions getDefault();
66
67 // Specify whether to emit .gcno files.
68 bool EmitNotes;
69
70 // Specify whether to modify the program to emit .gcda files when run.
71 bool EmitData;
72
73 // A four-byte version string. The meaning of a version string is described in
74 // gcc's gcov-io.h
75 char Version[4];
76
77 // Add the 'noredzone' attribute to added runtime library calls.
78 bool NoRedZone;
79
80 // Use atomic profile counter increments.
81 bool Atomic = false;
82
83 // Regexes separated by a semi-colon to filter the files to instrument.
84 std::string Filter;
85
86 // Regexes separated by a semi-colon to filter the files to not instrument.
87 std::string Exclude;
88 };
89
90 // The pgo-specific indirect call promotion function declared below is used by
91 // the pgo-driven indirect call promotion and sample profile passes. It's a
92 // wrapper around llvm::promoteCall, et al. that additionally computes !prof
93 // metadata. We place it in a pgo namespace so it's not confused with the
94 // generic utilities.
95 namespace pgo {
96
97 // Helper function that transforms CB (either an indirect-call instruction, or
98 // an invoke instruction , to a conditional call to F. This is like:
99 // if (Inst.CalledValue == F)
100 // F(...);
101 // else
102 // Inst(...);
103 // end
104 // TotalCount is the profile count value that the instruction executes.
105 // Count is the profile count value that F is the target function.
106 // These two values are used to update the branch weight.
107 // If \p AttachProfToDirectCall is true, a prof metadata is attached to the
108 // new direct call to contain \p Count.
109 // Returns the promoted direct call instruction.
110 LLVM_ABI CallBase &promoteIndirectCall(CallBase &CB, Function *F,
111 uint64_t Count, uint64_t TotalCount,
112 bool AttachProfToDirectCall,
113 OptimizationRemarkEmitter *ORE);
114 } // namespace pgo
115
116 /// Options for the frontend instrumentation based profiling pass.
117 struct InstrProfOptions {
118 // Add the 'noredzone' attribute to added runtime library calls.
119 bool NoRedZone = false;
120
121 // Do counter register promotion
122 bool DoCounterPromotion = false;
123
124 // Use atomic profile counter increments.
125 bool Atomic = false;
126
127 // Use BFI to guide register promotion
128 bool UseBFIInPromotion = false;
129
130 // Use sampling to reduce the profile instrumentation runtime overhead.
131 bool Sampling = false;
132
133 // Name of the profile file to use as output
134 std::string InstrProfileOutput;
135
136 InstrProfOptions() = default;
137 };
138
139 // Create the variable for profile sampling.
140 LLVM_ABI void createProfileSamplingVar(Module &M);
141
142 // Options for sanitizer coverage instrumentation.
143 struct SanitizerCoverageOptions {
144 enum Type {
145 SCK_None = 0,
146 SCK_Function,
147 SCK_BB,
148 SCK_Edge
149 } CoverageType = SCK_None;
150 bool IndirectCalls = false;
151 bool TraceBB = false;
152 bool TraceCmp = false;
153 bool TraceDiv = false;
154 bool TraceGep = false;
155 bool Use8bitCounters = false;
156 bool TracePC = false;
157 bool TracePCGuard = false;
158 bool Inline8bitCounters = false;
159 bool InlineBoolFlag = false;
160 bool PCTable = false;
161 bool NoPrune = false;
162 bool StackDepth = false;
163 bool TraceLoads = false;
164 bool TraceStores = false;
165 bool CollectControlFlow = false;
166 bool GatedCallbacks = false;
167 int StackDepthCallbackMin = 0;
168
169 SanitizerCoverageOptions() = default;
170 };
171
172 /// Calculate what to divide by to scale counts.
173 ///
174 /// Given the maximum count, calculate a divisor that will scale all the
175 /// weights to strictly less than std::numeric_limits<uint32_t>::max().
calculateCountScale(uint64_t MaxCount)176 static inline uint64_t calculateCountScale(uint64_t MaxCount) {
177 return MaxCount < std::numeric_limits<uint32_t>::max()
178 ? 1
179 : MaxCount / std::numeric_limits<uint32_t>::max() + 1;
180 }
181
182 /// Scale an individual branch count.
183 ///
184 /// Scale a 64-bit weight down to 32-bits using \c Scale.
185 ///
scaleBranchCount(uint64_t Count,uint64_t Scale)186 static inline uint32_t scaleBranchCount(uint64_t Count, uint64_t Scale) {
187 uint64_t Scaled = Count / Scale;
188 assert(Scaled <= std::numeric_limits<uint32_t>::max() && "overflow 32-bits");
189 return Scaled;
190 }
191
192 // Use to ensure the inserted instrumentation has a DebugLocation; if none is
193 // attached to the source instruction, try to use a DILocation with offset 0
194 // scoped to surrounding function (if it has a DebugLocation).
195 //
196 // Some non-call instructions may be missing debug info, but when inserting
197 // instrumentation calls, some builds (e.g. LTO) want calls to have debug info
198 // if the enclosing function does.
199 struct InstrumentationIRBuilder : IRBuilder<> {
ensureDebugInfoInstrumentationIRBuilder200 static void ensureDebugInfo(IRBuilder<> &IRB, const Function &F) {
201 if (IRB.getCurrentDebugLocation())
202 return;
203 if (DISubprogram *SP = F.getSubprogram())
204 IRB.SetCurrentDebugLocation(DILocation::get(SP->getContext(), 0, 0, SP));
205 }
206
InstrumentationIRBuilderInstrumentationIRBuilder207 explicit InstrumentationIRBuilder(Instruction *IP) : IRBuilder<>(IP) {
208 ensureDebugInfo(*this, *IP->getFunction());
209 }
210
InstrumentationIRBuilderInstrumentationIRBuilder211 explicit InstrumentationIRBuilder(BasicBlock *BB, BasicBlock::iterator It)
212 : IRBuilder<>(BB, It) {
213 ensureDebugInfo(*this, *BB->getParent());
214 }
215 };
216 } // end namespace llvm
217
218 #endif // LLVM_TRANSFORMS_INSTRUMENTATION_H
219