llvm/lib/Transforms/Utils/EntryExitInstrumenter.cpp

   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/TargetParser/Triple.h"
  19
  20 using namespace llvm;
  21
  22 static void insertCall(Function &CurFn, StringRef Func,
  23                        Instruction *InsertionPt, DebugLoc DL) {
  24   Module &M = *InsertionPt->getParent()->getParent()->getParent();
  25   LLVMContext &C = InsertionPt->getParent()->getContext();
  26
  27   if (Func == "mcount" ||
  28       Func == ".mcount" ||
  29       Func == "llvm.arm.gnu.eabi.mcount" ||
  30       Func == "\01_mcount" ||
  31       Func == "\01mcount" ||
  32       Func == "__mcount" ||
  33       Func == "_mcount" ||
  34       Func == "__cyg_profile_func_enter_bare") {
  35     Triple TargetTriple(M.getTargetTriple());
  36     if (TargetTriple.isOSAIX() && Func == "__mcount") {
  37       Type *SizeTy = M.getDataLayout().getIntPtrType(C);
  38       Type *SizePtrTy = PointerType::getUnqual(C);
  39       GlobalVariable *GV = new GlobalVariable(M, SizeTy, /*isConstant=*/false,
  40                                               GlobalValue::InternalLinkage,
  41                                               ConstantInt::get(SizeTy, 0));
  42       CallInst *Call = CallInst::Create(
  43           M.getOrInsertFunction(Func,
  44                                 FunctionType::get(Type::getVoidTy(C), {SizePtrTy},
  45                                                   /*isVarArg=*/false)),
  46           {GV}, "", InsertionPt);
  47       Call->setDebugLoc(DL);
  48     } else {
  49       FunctionCallee Fn = M.getOrInsertFunction(Func, Type::getVoidTy(C));
  50       CallInst *Call = CallInst::Create(Fn, "", InsertionPt);
  51       Call->setDebugLoc(DL);
  52     }
  53     return;
  54   }
  55
  56   if (Func == "__cyg_profile_func_enter" || Func == "__cyg_profile_func_exit") {
  57     Type *ArgTypes[] = {Type::getInt8PtrTy(C), Type::getInt8PtrTy(C)};
  58
  59     FunctionCallee Fn = M.getOrInsertFunction(
  60         Func, FunctionType::get(Type::getVoidTy(C), ArgTypes, false));
  61
  62     Instruction *RetAddr = CallInst::Create(
  63         Intrinsic::getDeclaration(&M, Intrinsic::returnaddress),
  64         ArrayRef<Value *>(ConstantInt::get(Type::getInt32Ty(C), 0)), "",
  65         InsertionPt);
  66     RetAddr->setDebugLoc(DL);
  67
  68     Value *Args[] = {ConstantExpr::getBitCast(&CurFn, Type::getInt8PtrTy(C)),
  69                      RetAddr};
  70
  71     CallInst *Call =
  72         CallInst::Create(Fn, ArrayRef<Value *>(Args), "", InsertionPt);
  73     Call->setDebugLoc(DL);
  74     return;
  75   }
  76
  77   // We only know how to call a fixed set of instrumentation functions, because
  78   // they all expect different arguments, etc.
  79   report_fatal_error(Twine("Unknown instrumentation function: '") + Func + "'");
  80 }
  81
  82 static bool runOnFunction(Function &F, bool PostInlining) {
  83   // The asm in a naked function may reasonably expect the argument registers
  84   // and the return address register (if present) to be live. An inserted
  85   // function call will clobber these registers. Simply skip naked functions for
  86   // all targets.
  87   if (F.hasFnAttribute(Attribute::Naked))
  88     return false;
  89
  90   StringRef EntryAttr = PostInlining ? "instrument-function-entry-inlined"
  91                                      : "instrument-function-entry";
  92
  93   StringRef ExitAttr = PostInlining ? "instrument-function-exit-inlined"
  94                                     : "instrument-function-exit";
  95
  96   StringRef EntryFunc = F.getFnAttribute(EntryAttr).getValueAsString();
  97   StringRef ExitFunc = F.getFnAttribute(ExitAttr).getValueAsString();
  98
  99   bool Changed = false;
 100
 101   // If the attribute is specified, insert instrumentation and then "consume"
 102   // the attribute so that it's not inserted again if the pass should happen to
 103   // run later for some reason.
 104
 105   if (!EntryFunc.empty()) {
 106     DebugLoc DL;
 107     if (auto SP = F.getSubprogram())
 108       DL = DILocation::get(SP->getContext(), SP->getScopeLine(), 0, SP);
 109
 110     insertCall(F, EntryFunc, &*F.begin()->getFirstInsertionPt(), DL);
 111     Changed = true;
 112     F.removeFnAttr(EntryAttr);
 113   }
 114
 115   if (!ExitFunc.empty()) {
 116     for (BasicBlock &BB : F) {
 117       Instruction *T = BB.getTerminator();
 118       if (!isa<ReturnInst>(T))
 119         continue;
 120
 121       // If T is preceded by a musttail call, that's the real terminator.
 122       if (CallInst *CI = BB.getTerminatingMustTailCall())
 123         T = CI;
 124
 125       DebugLoc DL;
 126       if (DebugLoc TerminatorDL = T->getDebugLoc())
 127         DL = TerminatorDL;
 128       else if (auto SP = F.getSubprogram())
 129         DL = DILocation::get(SP->getContext(), 0, 0, SP);
 130
 131       insertCall(F, ExitFunc, T, DL);
 132       Changed = true;
 133     }
 134     F.removeFnAttr(ExitAttr);
 135   }
 136
 137   return Changed;
 138 }
 139
 140 PreservedAnalyses
 141 llvm::EntryExitInstrumenterPass::run(Function &F, FunctionAnalysisManager &AM) {
 142   runOnFunction(F, PostInlining);
 143   PreservedAnalyses PA;
 144   PA.preserveSet<CFGAnalyses>();
 145   return PA;
 146 }
 147
 148 void llvm::EntryExitInstrumenterPass::printPipeline(
 149     raw_ostream &OS, function_ref<StringRef(StringRef)> MapClassName2PassName) {
 150   static_cast<PassInfoMixin<llvm::EntryExitInstrumenterPass> *>(this)
 151       ->printPipeline(OS, MapClassName2PassName);
 152   OS << '<';
 153   if (PostInlining)
 154     OS << "post-inline";
 155   OS << '>';
 156 }