1 //===- EntryExitInstrumenter.cpp - Function Entry/Exit Instrumentation ----===//
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 #include "llvm/Transforms/Utils/EntryExitInstrumenter.h"
10 #include "llvm/ADT/Triple.h"
11 #include "llvm/Analysis/GlobalsModRef.h"
12 #include "llvm/IR/DebugInfoMetadata.h"
13 #include "llvm/IR/Dominators.h"
14 #include "llvm/IR/Function.h"
15 #include "llvm/IR/Instructions.h"
16 #include "llvm/IR/Intrinsics.h"
17 #include "llvm/IR/Module.h"
18 #include "llvm/IR/Type.h"
19 #include "llvm/InitializePasses.h"
20 #include "llvm/Pass.h"
21 #include "llvm/Transforms/Utils.h"
22
23 using namespace llvm;
24
insertCall(Function & CurFn,StringRef Func,Instruction * InsertionPt,DebugLoc DL)25 static void insertCall(Function &CurFn, StringRef Func,
26 Instruction *InsertionPt, DebugLoc DL) {
27 Module &M = *InsertionPt->getParent()->getParent()->getParent();
28 LLVMContext &C = InsertionPt->getParent()->getContext();
29
30 if (Func == "mcount" ||
31 Func == ".mcount" ||
32 Func == "llvm.arm.gnu.eabi.mcount" ||
33 Func == "\01_mcount" ||
34 Func == "\01mcount" ||
35 Func == "__mcount" ||
36 Func == "_mcount" ||
37 Func == "__cyg_profile_func_enter_bare") {
38 Triple TargetTriple(M.getTargetTriple());
39 if (TargetTriple.isOSAIX() && Func == "__mcount") {
40 Type *SizeTy = M.getDataLayout().getIntPtrType(C);
41 Type *SizePtrTy = SizeTy->getPointerTo();
42 GlobalVariable *GV = new GlobalVariable(M, SizeTy, /*isConstant=*/false,
43 GlobalValue::InternalLinkage,
44 ConstantInt::get(SizeTy, 0));
45 CallInst *Call = CallInst::Create(
46 M.getOrInsertFunction(Func,
47 FunctionType::get(Type::getVoidTy(C), {SizePtrTy},
48 /*isVarArg=*/false)),
49 {GV}, "", InsertionPt);
50 Call->setDebugLoc(DL);
51 } else {
52 FunctionCallee Fn = M.getOrInsertFunction(Func, Type::getVoidTy(C));
53 CallInst *Call = CallInst::Create(Fn, "", InsertionPt);
54 Call->setDebugLoc(DL);
55 }
56 return;
57 }
58
59 if (Func == "__cyg_profile_func_enter" || Func == "__cyg_profile_func_exit") {
60 Type *ArgTypes[] = {Type::getInt8PtrTy(C), Type::getInt8PtrTy(C)};
61
62 FunctionCallee Fn = M.getOrInsertFunction(
63 Func, FunctionType::get(Type::getVoidTy(C), ArgTypes, false));
64
65 Instruction *RetAddr = CallInst::Create(
66 Intrinsic::getDeclaration(&M, Intrinsic::returnaddress),
67 ArrayRef<Value *>(ConstantInt::get(Type::getInt32Ty(C), 0)), "",
68 InsertionPt);
69 RetAddr->setDebugLoc(DL);
70
71 Value *Args[] = {ConstantExpr::getBitCast(&CurFn, Type::getInt8PtrTy(C)),
72 RetAddr};
73
74 CallInst *Call =
75 CallInst::Create(Fn, ArrayRef<Value *>(Args), "", InsertionPt);
76 Call->setDebugLoc(DL);
77 return;
78 }
79
80 // We only know how to call a fixed set of instrumentation functions, because
81 // they all expect different arguments, etc.
82 report_fatal_error(Twine("Unknown instrumentation function: '") + Func + "'");
83 }
84
runOnFunction(Function & F,bool PostInlining)85 static bool runOnFunction(Function &F, bool PostInlining) {
86 StringRef EntryAttr = PostInlining ? "instrument-function-entry-inlined"
87 : "instrument-function-entry";
88
89 StringRef ExitAttr = PostInlining ? "instrument-function-exit-inlined"
90 : "instrument-function-exit";
91
92 StringRef EntryFunc = F.getFnAttribute(EntryAttr).getValueAsString();
93 StringRef ExitFunc = F.getFnAttribute(ExitAttr).getValueAsString();
94
95 bool Changed = false;
96
97 // If the attribute is specified, insert instrumentation and then "consume"
98 // the attribute so that it's not inserted again if the pass should happen to
99 // run later for some reason.
100
101 if (!EntryFunc.empty()) {
102 DebugLoc DL;
103 if (auto SP = F.getSubprogram())
104 DL = DILocation::get(SP->getContext(), SP->getScopeLine(), 0, SP);
105
106 insertCall(F, EntryFunc, &*F.begin()->getFirstInsertionPt(), DL);
107 Changed = true;
108 F.removeFnAttr(EntryAttr);
109 }
110
111 if (!ExitFunc.empty()) {
112 for (BasicBlock &BB : F) {
113 Instruction *T = BB.getTerminator();
114 if (!isa<ReturnInst>(T))
115 continue;
116
117 // If T is preceded by a musttail call, that's the real terminator.
118 if (CallInst *CI = BB.getTerminatingMustTailCall())
119 T = CI;
120
121 DebugLoc DL;
122 if (DebugLoc TerminatorDL = T->getDebugLoc())
123 DL = TerminatorDL;
124 else if (auto SP = F.getSubprogram())
125 DL = DILocation::get(SP->getContext(), 0, 0, SP);
126
127 insertCall(F, ExitFunc, T, DL);
128 Changed = true;
129 }
130 F.removeFnAttr(ExitAttr);
131 }
132
133 return Changed;
134 }
135
136 PreservedAnalyses
run(Function & F,FunctionAnalysisManager & AM)137 llvm::EntryExitInstrumenterPass::run(Function &F, FunctionAnalysisManager &AM) {
138 runOnFunction(F, PostInlining);
139 PreservedAnalyses PA;
140 PA.preserveSet<CFGAnalyses>();
141 return PA;
142 }
143
printPipeline(raw_ostream & OS,function_ref<StringRef (StringRef)> MapClassName2PassName)144 void llvm::EntryExitInstrumenterPass::printPipeline(
145 raw_ostream &OS, function_ref<StringRef(StringRef)> MapClassName2PassName) {
146 static_cast<PassInfoMixin<llvm::EntryExitInstrumenterPass> *>(this)
147 ->printPipeline(OS, MapClassName2PassName);
148 OS << "<";
149 if (PostInlining)
150 OS << "post-inline";
151 OS << ">";
152 }
153