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/*========================== begin_copyright_notice ============================
Copyright (C) 2025 Intel Corporation
SPDX-License-Identifier: MIT
============================= end_copyright_notice ===========================*/
#include "common/LLVMWarningsPush.hpp"
#include <llvm/Support/CommandLine.h>
#include <llvm/Support/Debug.h>
#include "common/LLVMWarningsPop.hpp"
#include "Compiler/Optimizer/HoistConvOpToDom.hpp"
#include "Compiler/IGCPassSupport.h"
#include "Probe/Assertion.h"
#define DEBUG_TYPE "HoistConvOpToDom"
using namespace llvm;
using namespace IGC;
#define PASS_FLAG "igc-hoist-conv-op-to-dom"
#define PASS_DESCRIPTION "Hoist conversion operations to dominator"
#define PASS_CFG_ONLY false
#define PASS_ANALYSIS false
IGC_INITIALIZE_PASS_BEGIN(HoistConvOpToDom, PASS_FLAG, PASS_DESCRIPTION, PASS_CFG_ONLY, PASS_ANALYSIS)
IGC_INITIALIZE_PASS_DEPENDENCY(CodeGenContextWrapper)
IGC_INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
IGC_INITIALIZE_PASS_END(HoistConvOpToDom, PASS_FLAG, PASS_DESCRIPTION, PASS_CFG_ONLY, PASS_ANALYSIS)
namespace IGC {
char HoistConvOpToDom::ID = 0;
HoistConvOpToDom::HoistConvOpToDom() : FunctionPass(ID) {
initializeHoistConvOpToDomPass(*PassRegistry::getPassRegistry());
}
BasicBlock *HoistConvOpToDom::findNearestCommonDominator(const PHINode &PHI) const {
BasicBlock *CommonDominator = nullptr;
for (unsigned i = 0; i < PHI.getNumIncomingValues(); ++i) {
BasicBlock *IncomingBB = PHI.getIncomingBlock(i);
if (CommonDominator == nullptr) {
CommonDominator = IncomingBB;
continue;
}
CommonDominator = m_DT->findNearestCommonDominator(CommonDominator, IncomingBB);
}
return CommonDominator;
}
bool HoistConvOpToDom::runOnFunction(Function &F) {
m_CGCtx = getAnalysis<CodeGenContextWrapper>().getCodeGenContext();
m_DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
bool Changed = false;
for (auto &BB : F) {
for (auto &PHI : make_early_inc_range(BB.phis())) {
Value *FirstIncoming = PHI.getIncomingValue(0);
CastInst *FirstCast = dyn_cast<CastInst>(FirstIncoming);
if (!FirstCast)
continue;
LLVM_DEBUG(dbgs() << "HoistConvOpToDom: Found PHI with cast: " << *FirstCast << "\n");
SmallPtrSet<Instruction *, 4> ToUpdate;
bool AllSame = true;
for (unsigned i = 1; i < PHI.getNumIncomingValues(); ++i) {
Value *Incoming = PHI.getIncomingValue(i);
if (Incoming == FirstCast)
continue;
Instruction *IncomingInst = dyn_cast<Instruction>(Incoming);
if (!IncomingInst || !IncomingInst->isIdenticalTo(FirstCast)) {
AllSame = false;
break;
}
ToUpdate.insert(cast<Instruction>(Incoming));
}
if (!AllSame)
continue;
if (ToUpdate.empty())
continue;
auto *CommonDominator = findNearestCommonDominator(PHI);
if (!CommonDominator) {
IGC_ASSERT_MESSAGE(0, "Common dominator not found");
continue;
}
FirstCast->moveBefore(CommonDominator->getTerminator());
for (auto *I : ToUpdate) {
LLVM_DEBUG(dbgs() << "HoistConvOpToDom: Replacing " << *I << " with " << *FirstCast << "\n");
I->replaceAllUsesWith(FirstCast);
I->eraseFromParent();
}
PHI.replaceAllUsesWith(FirstCast);
PHI.eraseFromParent();
Changed = true;
}
}
return Changed;
}
} // namespace IGC
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