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/Analysis/GlobalsModRef.h" 11 #include "llvm/IR/DebugInfoMetadata.h" 12 #include "llvm/IR/Dominators.h" 13 #include "llvm/IR/Function.h" 14 #include "llvm/IR/Instructions.h" 15 #include "llvm/IR/Intrinsics.h" 16 #include "llvm/IR/Module.h" 17 #include "llvm/IR/Type.h" 18 #include "llvm/InitializePasses.h" 19 #include "llvm/TargetParser/Triple.h" 20 #include "llvm/Pass.h" 21 #include "llvm/Transforms/Utils.h" 22 23 using namespace llvm; 24 insertCall(Function & CurFn,StringRef Func,BasicBlock::iterator InsertionPt,DebugLoc DL)25 static void insertCall(Function &CurFn, StringRef Func, 26 BasicBlock::iterator 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 = PointerType::getUnqual(C); 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[] = {PointerType::getUnqual(C), PointerType::getUnqual(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[] = {&CurFn, RetAddr}; 72 CallInst *Call = 73 CallInst::Create(Fn, ArrayRef<Value *>(Args), "", InsertionPt); 74 Call->setDebugLoc(DL); 75 return; 76 } 77 78 // We only know how to call a fixed set of instrumentation functions, because 79 // they all expect different arguments, etc. 80 report_fatal_error(Twine("Unknown instrumentation function: '") + Func + "'"); 81 } 82 runOnFunction(Function & F,bool PostInlining)83 static bool runOnFunction(Function &F, bool PostInlining) { 84 // The asm in a naked function may reasonably expect the argument registers 85 // and the return address register (if present) to be live. An inserted 86 // function call will clobber these registers. Simply skip naked functions for 87 // all targets. 88 if (F.hasFnAttribute(Attribute::Naked)) 89 return false; 90 91 StringRef EntryAttr = PostInlining ? "instrument-function-entry-inlined" 92 : "instrument-function-entry"; 93 94 StringRef ExitAttr = PostInlining ? "instrument-function-exit-inlined" 95 : "instrument-function-exit"; 96 97 StringRef EntryFunc = F.getFnAttribute(EntryAttr).getValueAsString(); 98 StringRef ExitFunc = F.getFnAttribute(ExitAttr).getValueAsString(); 99 100 bool Changed = false; 101 102 // If the attribute is specified, insert instrumentation and then "consume" 103 // the attribute so that it's not inserted again if the pass should happen to 104 // run later for some reason. 105 106 if (!EntryFunc.empty()) { 107 DebugLoc DL; 108 if (auto SP = F.getSubprogram()) 109 DL = DILocation::get(SP->getContext(), SP->getScopeLine(), 0, SP); 110 111 insertCall(F, EntryFunc, F.begin()->getFirstInsertionPt(), DL); 112 Changed = true; 113 F.removeFnAttr(EntryAttr); 114 } 115 116 if (!ExitFunc.empty()) { 117 for (BasicBlock &BB : F) { 118 Instruction *T = BB.getTerminator(); 119 if (!isa<ReturnInst>(T)) 120 continue; 121 122 // If T is preceded by a musttail call, that's the real terminator. 123 if (CallInst *CI = BB.getTerminatingMustTailCall()) 124 T = CI; 125 126 DebugLoc DL; 127 if (DebugLoc TerminatorDL = T->getDebugLoc()) 128 DL = TerminatorDL; 129 else if (auto SP = F.getSubprogram()) 130 DL = DILocation::get(SP->getContext(), 0, 0, SP); 131 132 insertCall(F, ExitFunc, T->getIterator(), DL); 133 Changed = true; 134 } 135 F.removeFnAttr(ExitAttr); 136 } 137 138 return Changed; 139 } 140 141 namespace { 142 struct PostInlineEntryExitInstrumenter : public FunctionPass { 143 static char ID; PostInlineEntryExitInstrumenter__anonfba2004a0111::PostInlineEntryExitInstrumenter144 PostInlineEntryExitInstrumenter() : FunctionPass(ID) { 145 initializePostInlineEntryExitInstrumenterPass( 146 *PassRegistry::getPassRegistry()); 147 } getAnalysisUsage__anonfba2004a0111::PostInlineEntryExitInstrumenter148 void getAnalysisUsage(AnalysisUsage &AU) const override { 149 AU.addPreserved<GlobalsAAWrapperPass>(); 150 AU.addPreserved<DominatorTreeWrapperPass>(); 151 } runOnFunction__anonfba2004a0111::PostInlineEntryExitInstrumenter152 bool runOnFunction(Function &F) override { return ::runOnFunction(F, true); } 153 }; 154 char PostInlineEntryExitInstrumenter::ID = 0; 155 } 156 157 INITIALIZE_PASS_BEGIN( 158 PostInlineEntryExitInstrumenter, "post-inline-ee-instrument", 159 "Instrument function entry/exit with calls to e.g. mcount() " 160 "(post inlining)", 161 false, false) INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)162 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass) 163 INITIALIZE_PASS_END( 164 PostInlineEntryExitInstrumenter, "post-inline-ee-instrument", 165 "Instrument function entry/exit with calls to e.g. mcount() " 166 "(post inlining)", 167 false, false) 168 169 FunctionPass *llvm::createPostInlineEntryExitInstrumenterPass() { 170 return new PostInlineEntryExitInstrumenter(); 171 } 172 173 PreservedAnalyses run(Function & F,FunctionAnalysisManager & AM)174 llvm::EntryExitInstrumenterPass::run(Function &F, FunctionAnalysisManager &AM) { 175 if (!runOnFunction(F, PostInlining)) 176 return PreservedAnalyses::all(); 177 PreservedAnalyses PA; 178 PA.preserveSet<CFGAnalyses>(); 179 return PA; 180 } 181 printPipeline(raw_ostream & OS,function_ref<StringRef (StringRef)> MapClassName2PassName)182 void llvm::EntryExitInstrumenterPass::printPipeline( 183 raw_ostream &OS, function_ref<StringRef(StringRef)> MapClassName2PassName) { 184 static_cast<PassInfoMixin<llvm::EntryExitInstrumenterPass> *>(this) 185 ->printPipeline(OS, MapClassName2PassName); 186 OS << '<'; 187 if (PostInlining) 188 OS << "post-inline"; 189 OS << '>'; 190 } 191