| 1 | //===- X86MacroFusion.cpp - X86 Macro Fusion ------------------------------===// |
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| 2 | // |
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| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
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| 4 | // See https://llvm.org/LICENSE.txt for license information. |
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| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
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| 6 | // |
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| 7 | //===----------------------------------------------------------------------===// |
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| 8 | // |
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| 9 | /// \file This file contains the X86 implementation of the DAG scheduling |
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| 10 | /// mutation to pair instructions back to back. |
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| 11 | // |
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| 12 | //===----------------------------------------------------------------------===// |
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| 13 | |
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| 14 | #include "X86MacroFusion.h" |
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| 15 | #include "MCTargetDesc/X86BaseInfo.h" |
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| 16 | #include "X86Subtarget.h" |
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| 17 | #include "llvm/CodeGen/MacroFusion.h" |
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| 18 | #include "llvm/CodeGen/ScheduleDAGMutation.h" |
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| 19 | #include "llvm/CodeGen/TargetInstrInfo.h" |
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| 20 | |
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| 21 | using namespace llvm; |
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| 22 | |
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| 23 | static X86::FirstMacroFusionInstKind classifyFirst(const MachineInstr &MI) { |
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| 24 | return X86::classifyFirstOpcodeInMacroFusion(Opcode: MI.getOpcode()); |
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| 25 | } |
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| 26 | |
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| 27 | static X86::SecondMacroFusionInstKind classifySecond(const MachineInstr &MI) { |
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| 28 | X86::CondCode CC = X86::getCondFromBranch(MI); |
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| 29 | return X86::classifySecondCondCodeInMacroFusion(CC); |
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| 30 | } |
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| 31 | |
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| 32 | /// Check if the instr pair, FirstMI and SecondMI, should be fused |
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| 33 | /// together. Given SecondMI, when FirstMI is unspecified, then check if |
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| 34 | /// SecondMI may be part of a fused pair at all. |
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| 35 | static bool shouldScheduleAdjacent(const TargetInstrInfo &TII, |
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| 36 | const TargetSubtargetInfo &TSI, |
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| 37 | const MachineInstr *FirstMI, |
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| 38 | const MachineInstr &SecondMI) { |
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| 39 | const X86Subtarget &ST = static_cast<const X86Subtarget &>(TSI); |
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| 40 | |
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| 41 | // Check if this processor supports any kind of fusion. |
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| 42 | if (!(ST.hasBranchFusion() || ST.hasMacroFusion())) |
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| 43 | return false; |
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| 44 | |
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| 45 | const X86::SecondMacroFusionInstKind BranchKind = classifySecond(MI: SecondMI); |
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| 46 | |
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| 47 | if (BranchKind == X86::SecondMacroFusionInstKind::Invalid) |
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| 48 | return false; // Second cannot be fused with anything. |
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| 49 | |
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| 50 | if (FirstMI == nullptr) |
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| 51 | return true; // We're only checking whether Second can be fused at all. |
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| 52 | |
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| 53 | const X86::FirstMacroFusionInstKind TestKind = classifyFirst(MI: *FirstMI); |
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| 54 | |
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| 55 | if (ST.hasBranchFusion()) { |
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| 56 | // Branch fusion can merge CMP and TEST with all conditional jumps. |
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| 57 | return (TestKind == X86::FirstMacroFusionInstKind::Cmp || |
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| 58 | TestKind == X86::FirstMacroFusionInstKind::Test); |
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| 59 | } |
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| 60 | |
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| 61 | if (ST.hasMacroFusion()) { |
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| 62 | return X86::isMacroFused(FirstKind: TestKind, SecondKind: BranchKind); |
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| 63 | } |
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| 64 | |
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| 65 | llvm_unreachable("unknown fusion type" ); |
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| 66 | } |
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| 67 | |
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| 68 | namespace llvm { |
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| 69 | |
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| 70 | std::unique_ptr<ScheduleDAGMutation> createX86MacroFusionDAGMutation() { |
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| 71 | return createMacroFusionDAGMutation(Predicates: shouldScheduleAdjacent, |
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| 72 | /*BranchOnly=*/true); |
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| 73 | } |
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| 74 | |
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| 75 | } // end namespace llvm |
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| 76 | |
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