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//===- LowerInvoke.cpp - Eliminate Invoke instructions --------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This transformation is designed for use by code generators which do not yet
// support stack unwinding. This pass converts 'invoke' instructions to 'call'
// instructions, so that any exception-handling 'landingpad' blocks become dead
// code (which can be removed by running the '-simplifycfg' pass afterwards).
//
//===----------------------------------------------------------------------===//
#include "llvm/Transforms/Utils/LowerInvoke.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Module.h"
#include "llvm/InitializePasses.h"
#include "llvm/Pass.h"
#include "llvm/Transforms/Utils.h"
using namespace llvm;
#define DEBUG_TYPE "lowerinvoke"
STATISTIC(NumInvokes, "Number of invokes replaced");
namespace {
class LowerInvokeLegacyPass : public FunctionPass {
public:
static char ID; // Pass identification, replacement for typeid
explicit LowerInvokeLegacyPass() : FunctionPass(ID) {
initializeLowerInvokeLegacyPassPass(*PassRegistry::getPassRegistry());
}
bool runOnFunction(Function &F) override;
};
}
char LowerInvokeLegacyPass::ID = 0;
INITIALIZE_PASS(LowerInvokeLegacyPass, "lowerinvoke",
"Lower invoke and unwind, for unwindless code generators",
false, false)
static bool runImpl(Function &F) {
bool Changed = false;
for (BasicBlock &BB : F)
if (InvokeInst *II = dyn_cast<InvokeInst>(BB.getTerminator())) {
SmallVector<Value *, 16> CallArgs(II->args());
SmallVector<OperandBundleDef, 1> OpBundles;
II->getOperandBundlesAsDefs(OpBundles);
// Insert a normal call instruction...
CallInst *NewCall =
CallInst::Create(II->getFunctionType(), II->getCalledOperand(),
CallArgs, OpBundles, "", II);
NewCall->takeName(II);
NewCall->setCallingConv(II->getCallingConv());
NewCall->setAttributes(II->getAttributes());
NewCall->setDebugLoc(II->getDebugLoc());
II->replaceAllUsesWith(NewCall);
// Insert an unconditional branch to the normal destination.
BranchInst::Create(II->getNormalDest(), II);
// Remove any PHI node entries from the exception destination.
II->getUnwindDest()->removePredecessor(&BB);
// Remove the invoke instruction now.
BB.getInstList().erase(II);
++NumInvokes;
Changed = true;
}
return Changed;
}
bool LowerInvokeLegacyPass::runOnFunction(Function &F) {
return runImpl(F);
}
namespace llvm {
char &LowerInvokePassID = LowerInvokeLegacyPass::ID;
// Public Interface To the LowerInvoke pass.
FunctionPass *createLowerInvokePass() { return new LowerInvokeLegacyPass(); }
PreservedAnalyses LowerInvokePass::run(Function &F,
FunctionAnalysisManager &AM) {
bool Changed = runImpl(F);
if (!Changed)
return PreservedAnalyses::all();
return PreservedAnalyses::none();
}
}
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