1 //===- LowerInvoke.cpp - Eliminate Invoke instructions --------------------===// 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 transformation is designed for use by code generators which do not yet 10 // support stack unwinding. This pass converts 'invoke' instructions to 'call' 11 // instructions, so that any exception-handling 'landingpad' blocks become dead 12 // code (which can be removed by running the '-simplifycfg' pass afterwards). 13 // 14 //===----------------------------------------------------------------------===// 15 16 #include "llvm/Transforms/Utils/LowerInvoke.h" 17 #include "llvm/ADT/SmallVector.h" 18 #include "llvm/ADT/Statistic.h" 19 #include "llvm/IR/Instructions.h" 20 #include "llvm/InitializePasses.h" 21 #include "llvm/Pass.h" 22 #include "llvm/Transforms/Utils.h" 23 using namespace llvm; 24 25 #define DEBUG_TYPE "lowerinvoke" 26 27 STATISTIC(NumInvokes, "Number of invokes replaced"); 28 29 namespace { 30 class LowerInvokeLegacyPass : public FunctionPass { 31 public: 32 static char ID; // Pass identification, replacement for typeid 33 explicit LowerInvokeLegacyPass() : FunctionPass(ID) { 34 initializeLowerInvokeLegacyPassPass(*PassRegistry::getPassRegistry()); 35 } 36 bool runOnFunction(Function &F) override; 37 }; 38 } 39 40 char LowerInvokeLegacyPass::ID = 0; 41 INITIALIZE_PASS(LowerInvokeLegacyPass, "lowerinvoke", 42 "Lower invoke and unwind, for unwindless code generators", 43 false, false) 44 45 static bool runImpl(Function &F) { 46 bool Changed = false; 47 for (BasicBlock &BB : F) 48 if (InvokeInst *II = dyn_cast<InvokeInst>(BB.getTerminator())) { 49 SmallVector<Value *, 16> CallArgs(II->args()); 50 SmallVector<OperandBundleDef, 1> OpBundles; 51 II->getOperandBundlesAsDefs(OpBundles); 52 // Insert a normal call instruction... 53 CallInst *NewCall = 54 CallInst::Create(II->getFunctionType(), II->getCalledOperand(), 55 CallArgs, OpBundles, "", II); 56 NewCall->takeName(II); 57 NewCall->setCallingConv(II->getCallingConv()); 58 NewCall->setAttributes(II->getAttributes()); 59 NewCall->setDebugLoc(II->getDebugLoc()); 60 II->replaceAllUsesWith(NewCall); 61 62 // Insert an unconditional branch to the normal destination. 63 BranchInst::Create(II->getNormalDest(), II); 64 65 // Remove any PHI node entries from the exception destination. 66 II->getUnwindDest()->removePredecessor(&BB); 67 68 // Remove the invoke instruction now. 69 BB.getInstList().erase(II); 70 71 ++NumInvokes; 72 Changed = true; 73 } 74 return Changed; 75 } 76 77 bool LowerInvokeLegacyPass::runOnFunction(Function &F) { 78 return runImpl(F); 79 } 80 81 namespace llvm { 82 char &LowerInvokePassID = LowerInvokeLegacyPass::ID; 83 84 // Public Interface To the LowerInvoke pass. 85 FunctionPass *createLowerInvokePass() { return new LowerInvokeLegacyPass(); } 86 87 PreservedAnalyses LowerInvokePass::run(Function &F, 88 FunctionAnalysisManager &AM) { 89 bool Changed = runImpl(F); 90 if (!Changed) 91 return PreservedAnalyses::all(); 92 93 return PreservedAnalyses::none(); 94 } 95 } 96