| //===- X86MacroFusion.cpp - X86 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 X86 implementation of the DAG scheduling |
| /// mutation to pair instructions back to back. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "X86MacroFusion.h" |
| #include "MCTargetDesc/X86BaseInfo.h" |
| #include "X86Subtarget.h" |
| #include "llvm/CodeGen/MacroFusion.h" |
| #include "llvm/CodeGen/TargetInstrInfo.h" |
| |
| using namespace llvm; |
| |
| static X86::FirstMacroFusionInstKind classifyFirst(const MachineInstr &MI) { |
| return X86::classifyFirstOpcodeInMacroFusion(MI.getOpcode()); |
| } |
| |
| static X86::SecondMacroFusionInstKind classifySecond(const MachineInstr &MI) { |
| X86::CondCode CC = X86::getCondFromBranch(MI); |
| return X86::classifySecondCondCodeInMacroFusion(CC); |
| } |
| |
| /// 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 X86Subtarget &ST = static_cast<const X86Subtarget &>(TSI); |
| |
| // Check if this processor supports any kind of fusion. |
| if (!(ST.hasBranchFusion() || ST.hasMacroFusion())) |
| return false; |
| |
| const X86::SecondMacroFusionInstKind BranchKind = classifySecond(SecondMI); |
| |
| if (BranchKind == X86::SecondMacroFusionInstKind::Invalid) |
| return false; // Second cannot be fused with anything. |
| |
| if (FirstMI == nullptr) |
| return true; // We're only checking whether Second can be fused at all. |
| |
| const X86::FirstMacroFusionInstKind TestKind = classifyFirst(*FirstMI); |
| |
| if (ST.hasBranchFusion()) { |
| // Branch fusion can merge CMP and TEST with all conditional jumps. |
| return (TestKind == X86::FirstMacroFusionInstKind::Cmp || |
| TestKind == X86::FirstMacroFusionInstKind::Test); |
| } |
| |
| if (ST.hasMacroFusion()) { |
| return X86::isMacroFused(TestKind, BranchKind); |
| } |
| |
| llvm_unreachable("unknown fusion type"); |
| } |
| |
| namespace llvm { |
| |
| std::unique_ptr<ScheduleDAGMutation> |
| createX86MacroFusionDAGMutation () { |
| return createBranchMacroFusionDAGMutation(shouldScheduleAdjacent); |
| } |
| |
| } // end namespace llvm |