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/*========================== begin_copyright_notice ============================
Copyright (C) 2019-2021 Intel Corporation
SPDX-License-Identifier: MIT
============================= end_copyright_notice ===========================*/
#include "Compiler/Optimizer/OpenCLPasses/UnreachableHandling/UnreachableHandling.hpp"
#include "Compiler/CodeGenPublic.h"
#include "Compiler/IGCPassSupport.h"
#include "common/LLVMWarningsPush.hpp"
#include <llvmWrapper/IR/BasicBlock.h>
#include <llvm/IR/Function.h>
#include <llvm/IR/Instructions.h>
#include "common/LLVMWarningsPop.hpp"
using namespace llvm;
using namespace IGC;
// Register pass to igc-opt
#define PASS_FLAG "igc-unreachable-handling"
#define PASS_DESCRIPTION "Make sure kernel has EOT instruction even if it hits unreachable code."
#define PASS_CFG_ONLY false
#define PASS_ANALYSIS false
IGC_INITIALIZE_PASS_BEGIN(UnreachableHandling, PASS_FLAG, PASS_DESCRIPTION, PASS_CFG_ONLY, PASS_ANALYSIS)
IGC_INITIALIZE_PASS_END(UnreachableHandling, PASS_FLAG, PASS_DESCRIPTION, PASS_CFG_ONLY, PASS_ANALYSIS)
char UnreachableHandling::ID = 0;
UnreachableHandling::UnreachableHandling() : FunctionPass(ID) {
initializeUnreachableHandlingPass(*PassRegistry::getPassRegistry());
}
void UnreachableHandling::visitUnreachableInst(UnreachableInst &I) { m_instsToReplace.push_back(&I); }
void IGC::UnreachableHandling::replaceUnreachable(llvm::UnreachableInst *I) {
assert(I);
IRBuilder<> builder(I->getContext());
Function *F = I->getFunction();
ReturnInst *ret =
F->getReturnType()->isVoidTy() ? builder.CreateRetVoid() : builder.CreateRet(UndefValue::get(F->getReturnType()));
// If this is the last instruction in the BB, just replace it with return instruction.
if (&I->getParent()->back() == I) {
IGCLLVM::pushBackInstruction(I->getParent(), ret);
I->eraseFromParent();
return;
}
// If there were some other instructions after, split the basic block and let DCE handle it.
auto BB = I->getParent();
BB->splitBasicBlock(I);
auto BBWithRet = BasicBlock::Create(F->getContext(), "", F);
IGCLLVM::pushBackInstruction(BBWithRet, ret);
cast<BranchInst>(BB->getTerminator())->setSuccessor(0, BBWithRet);
I->eraseFromParent();
}
bool UnreachableHandling::runOnFunction(Function &F) {
m_instsToReplace.clear();
visit(F);
for (auto I : m_instsToReplace) {
replaceUnreachable(I);
}
return m_instsToReplace.size() > 0;
}
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