75 lines
2.6 KiB
C++
75 lines
2.6 KiB
C++
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//===- X86MacroFusion.cpp - X86 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 X86 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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#include "X86MacroFusion.h"
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#include "MCTargetDesc/X86BaseInfo.h"
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#include "X86Subtarget.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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static X86::FirstMacroFusionInstKind classifyFirst(const MachineInstr &MI) {
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return X86::classifyFirstOpcodeInMacroFusion(MI.getOpcode());
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}
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static X86::SecondMacroFusionInstKind classifySecond(const MachineInstr &MI) {
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X86::CondCode CC = X86::getCondFromBranch(MI);
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return X86::classifySecondCondCodeInMacroFusion(CC);
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}
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/// Check if the instr pair, FirstMI and SecondMI, should be fused
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/// together. Given SecondMI, when FirstMI is unspecified, then check if
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/// SecondMI may be part of a fused pair at all.
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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 X86Subtarget &ST = static_cast<const X86Subtarget &>(TSI);
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// Check if this processor supports any kind of fusion.
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if (!(ST.hasBranchFusion() || ST.hasMacroFusion()))
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return false;
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const X86::SecondMacroFusionInstKind BranchKind = classifySecond(SecondMI);
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if (BranchKind == X86::SecondMacroFusionInstKind::Invalid)
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return false; // Second cannot be fused with anything.
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if (FirstMI == nullptr)
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return true; // We're only checking whether Second can be fused at all.
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const X86::FirstMacroFusionInstKind TestKind = classifyFirst(*FirstMI);
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if (ST.hasBranchFusion()) {
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// Branch fusion can merge CMP and TEST with all conditional jumps.
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return (TestKind == X86::FirstMacroFusionInstKind::Cmp ||
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TestKind == X86::FirstMacroFusionInstKind::Test);
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}
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if (ST.hasMacroFusion()) {
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return X86::isMacroFused(TestKind, BranchKind);
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}
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llvm_unreachable("unknown fusion type");
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}
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namespace llvm {
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std::unique_ptr<ScheduleDAGMutation>
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createX86MacroFusionDAGMutation () {
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return createBranchMacroFusionDAGMutation(shouldScheduleAdjacent);
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}
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} // end namespace llvm
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