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/*========================== begin_copyright_notice ============================
Copyright (C) 2024 Intel Corporation
SPDX-License-Identifier: MIT
============================= end_copyright_notice ===========================*/
#include "RemoveLoopDependency.hpp"
#include "Compiler/IGCPassSupport.h"
#include "common/LLVMWarningsPush.hpp"
#include "llvmWrapper/IR/DerivedTypes.h"
#include <llvm/IR/Constants.h>
#include "common/LLVMWarningsPop.hpp"
#include <vector>
using namespace llvm;
using namespace IGC;
char RemoveLoopDependency::ID = 0;
#define PASS_FLAG "remove-loop-dependency"
#define PASS_DESCRIPTION "Removing of fantom loop dependency."
#define PASS_CFG_ONLY false
#define PASS_ANALYSIS false
IGC_INITIALIZE_PASS_BEGIN(RemoveLoopDependency, PASS_FLAG, PASS_DESCRIPTION, PASS_CFG_ONLY, PASS_ANALYSIS)
IGC_INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)
IGC_INITIALIZE_PASS_END(RemoveLoopDependency, PASS_FLAG, PASS_DESCRIPTION, PASS_CFG_ONLY, PASS_ANALYSIS)
RemoveLoopDependency::RemoveLoopDependency() : FunctionPass(ID) {
initializeRemoveLoopDependencyPass(*PassRegistry::getPassRegistry());
}
bool RemoveLoopDependency::runOnFunction(Function &F) {
bool changed = false;
LoopInfo& LI = getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
for (auto* L : LI.getLoopsInPreorder())
changed |= processLoop(L);
return changed;
}
bool RemoveLoopDependency::processLoop(Loop *L)
{
bool changed = false;
for (auto &PHI : L->getHeader()->phis())
{
if (dyn_cast<IGCLLVM::FixedVectorType>(PHI.getType()))
changed |= RemoveDependency(&PHI, L);
}
return changed;
}
bool RemoveLoopDependency::RemoveDependency(PHINode *PHI, Loop *L) {
unsigned elemCount = cast<IGCLLVM::FixedVectorType>(PHI->getType())->getNumElements();
std::vector<bool> overwritten(elemCount, false);
Instruction *currentVector = PHI;
for (unsigned i = 0; i < elemCount; ++i) {
if (currentVector->getNumUses() != 1)
return false;
if (InsertElementInst *IEI = dyn_cast<InsertElementInst>(currentVector->user_back())) {
if (!L->contains(IEI))
return false;
if (ConstantInt *indexConst = dyn_cast<ConstantInt>(IEI->getOperand(2))) {
uint64_t index = indexConst->getZExtValue();
if (index >= elemCount || overwritten[index])
return false;
overwritten[index] = true;
currentVector = IEI;
continue;
}
}
return false;
}
Instruction *firstAssignment = PHI->user_back();
UndefValue *undefVector = UndefValue::get(firstAssignment->getOperand(0)->getType());
firstAssignment->setOperand(0, undefVector);
return true;
}
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