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/*========================== begin_copyright_notice ============================
Copyright (C) 2017-2022 Intel Corporation
SPDX-License-Identifier: MIT
============================= end_copyright_notice ===========================*/
#pragma once
#include "common/LLVMWarningsPush.hpp"
#include <llvm/Pass.h>
#include <llvm/IR/InstVisitor.h>
#include "common/LLVMWarningsPop.hpp"
#include "Compiler/CISACodeGen/WIAnalysis.hpp"
namespace IGC {
// This pass performs the following optimization:
//
// It adds a reduce instruction (GenISA.WaveAll) for the subgroup before the atomic float sum.
// It handles only float emulated uniform atomics.
//
// Emulated atomic before optimization
// back:
// %call1 = call i32 @llvm.genx.GenISA.intatomicrawA64.i32.p1i32.p1i32(i32 addrspace(1)* %1, i32 addrspace(1)* %1,
// i32 0, i32 9) %bc1 = bitcast i32 %call1 to float %operation = fadd fast float %bc1, -2.000000e+00 %bc2 = bitcast
// float %operation to i32 %call2 = call i32 @llvm.genx.GenISA.icmpxchgatomicrawA64.i32.p1i32.p1i32(i32
// addrspace(1)* %1, i32 addrspace(1)* %1, i32 %call1, i32 %bc2) %cmp = icmp eq i32 %call1, %call2 br i1 %cmp, label
// %exit, label %back
// exit:
// ret void
//
// Emulated atomic after optimization
// entry:
// %2 = call i16 @llvm.genx.GenISA.simdLaneId()
// %3 = zext i16 %2 to i32
// %4 = call float @llvm.genx.GenISA.WaveAll.f32(float -2.000000e+00, i8 9, i32 0)
// %5 = icmp eq i32 %3, 0
// br i1 %5, label %back, label %exit
// back:
// %call1 = call i32 @llvm.genx.GenISA.intatomicrawA64.i32.p1i32.p1i32(i32 addrspace(1)* %1, i32 addrspace(1)* %1,
// i32 0, i32 9) %bc1 = bitcast i32 %call1 to float %operation = fadd fast float %bc1, %4 %bc2 = bitcast float
// %operation to i32 %call2 = call i32 @llvm.genx.GenISA.icmpxchgatomicrawA64.i32.p1i32.p1i32(i32 addrspace(1)* %1,
// i32 addrspace(1)* %1, i32 %call1, i32 %bc2) %cmp = icmp eq i32 %call1, %call2 br i1 %cmp, label %exit, label
// %back
// exit:
// ret void
class AtomicOptPass : public llvm::FunctionPass {
public:
static char ID;
AtomicOptPass();
virtual llvm::StringRef getPassName() const override { return "Atomic Optimisation Pass"; }
virtual void getAnalysisUsage(llvm::AnalysisUsage &AU) const override {
AU.setPreservesAll();
AU.addRequired<WIAnalysis>();
}
virtual bool runOnFunction(llvm::Function &F) override;
private:
llvm::Instruction *createReduce(llvm::Instruction *Pos, llvm::Value *ValueForReduce);
llvm::Value *getSubgroupLocalIdBI(llvm::Instruction *Pos);
bool checkFloatAtomicEmulation(llvm::Instruction *Val, size_t &OperandPos);
bool Changed = false;
WIAnalysis *Wi = nullptr;
llvm::Module *M = nullptr;
};
} // namespace IGC
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