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/*========================== begin_copyright_notice ============================
Copyright (C) 2024 Intel Corporation
SPDX-License-Identifier: MIT
============================= end_copyright_notice ===========================*/
#pragma once
#include "common/LLVMWarningsPush.hpp"
#include <llvm/Pass.h>
#include <llvm/Analysis/LoopInfo.h>
#include "common/LLVMWarningsPop.hpp"
namespace IGC {
// This pass is designed to remove fantom dependency in a loop.
// When value that we get from PHI, is a vector, that is completely overwritten
// inside loop body and no other uses, then replace this value with usage of undef.
// Input IR:
// %1 = phi <4 x i32> [ undef, %for.body9.i ], [ %.124.vec.insert1133, %._crit_edge646.3 ]
// %2 = insertelement <4 x i32> %1, i32 %val1, i32 0
// %3 = insertelement <4 x i32> %2, i32 %val2, i32 1
// %4 = insertelement <4 x i32> %3, i32 %val3, i32 2
// %5 = insertelement <4 x i32> %4, i32 %val4, i32 3
//
// Output IR:
// %1 = phi <4 x i32> [ undef, %for.body9.i ], [ %.124.vec.insert1133, %._crit_edge646.3 ]
// %2 = insertelement <4 x i32> undef, i32 %val1, i32 0
// %3 = insertelement <4 x i32> %2, i32 %val2, i32 1
// %4 = insertelement <4 x i32> %3, i32 %val3, i32 2
// %5 = insertelement <4 x i32> %4, i32 %val4, i32 3
class RemoveLoopDependency : public llvm::FunctionPass {
public:
static char ID;
RemoveLoopDependency();
virtual llvm::StringRef getPassName() const override { return "RemoveLoopDependency"; }
virtual void getAnalysisUsage(llvm::AnalysisUsage &AU) const override { AU.addRequired<llvm::LoopInfoWrapperPass>(); }
virtual bool runOnFunction(llvm::Function &F) override;
bool processLoop(llvm::Loop *L);
bool RemoveDependency(llvm::PHINode *PHI, llvm::Loop *L);
};
} // namespace IGC
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