ARMMacroFusion.cpp
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//===- ARMMacroFusion.cpp - ARM Macro Fusion ----------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
/// \file This file contains the ARM implementation of the DAG scheduling
/// mutation to pair instructions back to back.
//
//===----------------------------------------------------------------------===//
#include "ARMMacroFusion.h"
#include "ARMSubtarget.h"
#include "llvm/CodeGen/MacroFusion.h"
#include "llvm/CodeGen/TargetInstrInfo.h"
namespace llvm {
// Fuse AES crypto encoding or decoding.
static bool isAESPair(const MachineInstr *FirstMI,
const MachineInstr &SecondMI) {
// Assume the 1st instr to be a wildcard if it is unspecified.
switch(SecondMI.getOpcode()) {
// AES encode.
case ARM::AESMC :
return FirstMI == nullptr || FirstMI->getOpcode() == ARM::AESE;
// AES decode.
case ARM::AESIMC:
return FirstMI == nullptr || FirstMI->getOpcode() == ARM::AESD;
}
return false;
}
// Fuse literal generation.
static bool isLiteralsPair(const MachineInstr *FirstMI,
const MachineInstr &SecondMI) {
// Assume the 1st instr to be a wildcard if it is unspecified.
if ((FirstMI == nullptr || FirstMI->getOpcode() == ARM::MOVi16) &&
SecondMI.getOpcode() == ARM::MOVTi16)
return true;
return false;
}
/// Check if the instr pair, FirstMI and SecondMI, should be fused
/// together. Given SecondMI, when FirstMI is unspecified, then check if
/// SecondMI may be part of a fused pair at all.
static bool shouldScheduleAdjacent(const TargetInstrInfo &TII,
const TargetSubtargetInfo &TSI,
const MachineInstr *FirstMI,
const MachineInstr &SecondMI) {
const ARMSubtarget &ST = static_cast<const ARMSubtarget&>(TSI);
if (ST.hasFuseAES() && isAESPair(FirstMI, SecondMI))
return true;
if (ST.hasFuseLiterals() && isLiteralsPair(FirstMI, SecondMI))
return true;
return false;
}
std::unique_ptr<ScheduleDAGMutation> createARMMacroFusionDAGMutation () {
return createMacroFusionDAGMutation(shouldScheduleAdjacent);
}
} // end namespace llvm