1//===- LowerInvoke.cpp - Eliminate Invoke instructions --------------------===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This transformation is designed for use by code generators which do not yet 11// support stack unwinding. This pass converts 'invoke' instructions to 'call' 12// instructions, so that any exception-handling 'landingpad' blocks become dead 13// code (which can be removed by running the '-simplifycfg' pass afterwards). 14// 15//===----------------------------------------------------------------------===// 16 17#include "llvm/ADT/SmallVector.h" 18#include "llvm/ADT/Statistic.h" 19#include "llvm/IR/Instructions.h" 20#include "llvm/IR/LLVMContext.h" 21#include "llvm/IR/Module.h" 22#include "llvm/Pass.h" 23#include "llvm/Transforms/Scalar.h" 24using namespace llvm; 25 26#define DEBUG_TYPE "lowerinvoke" 27 28STATISTIC(NumInvokes, "Number of invokes replaced"); 29 30namespace { 31 class LowerInvoke : public FunctionPass { 32 public: 33 static char ID; // Pass identification, replacement for typeid 34 explicit LowerInvoke() : FunctionPass(ID) { 35 initializeLowerInvokePass(*PassRegistry::getPassRegistry()); 36 } 37 bool runOnFunction(Function &F) override; 38 }; 39} 40 41char LowerInvoke::ID = 0; 42INITIALIZE_PASS(LowerInvoke, "lowerinvoke", 43 "Lower invoke and unwind, for unwindless code generators", 44 false, false) 45 46char &llvm::LowerInvokePassID = LowerInvoke::ID; 47 48// Public Interface To the LowerInvoke pass. 49FunctionPass *llvm::createLowerInvokePass() { 50 return new LowerInvoke(); 51} 52 53bool LowerInvoke::runOnFunction(Function &F) { 54 bool Changed = false; 55 for (BasicBlock &BB : F) 56 if (InvokeInst *II = dyn_cast<InvokeInst>(BB.getTerminator())) { 57 SmallVector<Value*,16> CallArgs(II->op_begin(), II->op_end() - 3); 58 // Insert a normal call instruction... 59 CallInst *NewCall = CallInst::Create(II->getCalledValue(), 60 CallArgs, "", II); 61 NewCall->takeName(II); 62 NewCall->setCallingConv(II->getCallingConv()); 63 NewCall->setAttributes(II->getAttributes()); 64 NewCall->setDebugLoc(II->getDebugLoc()); 65 II->replaceAllUsesWith(NewCall); 66 67 // Insert an unconditional branch to the normal destination. 68 BranchInst::Create(II->getNormalDest(), II); 69 70 // Remove any PHI node entries from the exception destination. 71 II->getUnwindDest()->removePredecessor(&BB); 72 73 // Remove the invoke instruction now. 74 BB.getInstList().erase(II); 75 76 ++NumInvokes; Changed = true; 77 } 78 return Changed; 79} 80