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