74 lines
2.4 KiB
C++
74 lines
2.4 KiB
C++
//===- RISCVMacroFusion.cpp - RISCV Macro Fusion --------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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/// \file This file contains the RISCV implementation of the DAG scheduling
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/// mutation to pair instructions back to back.
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//
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//===----------------------------------------------------------------------===//
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//
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#include "RISCVMacroFusion.h"
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#include "RISCVSubtarget.h"
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#include "llvm/CodeGen/MacroFusion.h"
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#include "llvm/CodeGen/TargetInstrInfo.h"
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using namespace llvm;
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// Fuse LUI followed by ADDI or ADDIW.
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// rd = imm[31:0] which decomposes to
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// lui rd, imm[31:12]
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// addi(w) rd, rd, imm[11:0]
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static bool isLUIADDI(const MachineInstr *FirstMI,
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const MachineInstr &SecondMI) {
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if (SecondMI.getOpcode() != RISCV::ADDI &&
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SecondMI.getOpcode() != RISCV::ADDIW)
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return false;
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// Assume the 1st instr to be a wildcard if it is unspecified.
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if (!FirstMI)
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return true;
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if (FirstMI->getOpcode() != RISCV::LUI)
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return false;
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// The first operand of ADDI might be a frame index.
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if (!SecondMI.getOperand(1).isReg())
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return false;
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Register FirstDest = FirstMI->getOperand(0).getReg();
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// Destination of LUI should be the ADDI(W) source register.
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if (SecondMI.getOperand(1).getReg() != FirstDest)
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return false;
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// If the input is virtual make sure this is the only user.
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if (FirstDest.isVirtual()) {
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auto &MRI = SecondMI.getMF()->getRegInfo();
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return MRI.hasOneNonDBGUse(FirstDest);
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}
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// If the FirstMI destination is non-virtual, it should match the SecondMI
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// destination.
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return SecondMI.getOperand(0).getReg() == FirstDest;
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}
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static bool shouldScheduleAdjacent(const TargetInstrInfo &TII,
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const TargetSubtargetInfo &TSI,
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const MachineInstr *FirstMI,
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const MachineInstr &SecondMI) {
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const RISCVSubtarget &ST = static_cast<const RISCVSubtarget &>(TSI);
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if (ST.hasLUIADDIFusion() && isLUIADDI(FirstMI, SecondMI))
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return true;
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return false;
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}
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std::unique_ptr<ScheduleDAGMutation> llvm::createRISCVMacroFusionDAGMutation() {
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return createMacroFusionDAGMutation(shouldScheduleAdjacent);
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}
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