1 //===- MacroFusion.h - Macro Fusion -----------------------------*- C++ -*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 /// \file This file contains the definition of the DAG scheduling mutation to 10 /// pair instructions back to back. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #ifndef LLVM_CODEGEN_MACROFUSION_H 15 #define LLVM_CODEGEN_MACROFUSION_H 16 17 #include <functional> 18 #include <memory> 19 20 namespace llvm { 21 22 class MachineInstr; 23 class ScheduleDAGMutation; 24 class TargetInstrInfo; 25 class TargetSubtargetInfo; 26 class ScheduleDAGInstrs; 27 class SUnit; 28 29 /// Check if the instr pair, FirstMI and SecondMI, should be fused 30 /// together. Given SecondMI, when FirstMI is unspecified, then check if 31 /// SecondMI may be part of a fused pair at all. 32 using ShouldSchedulePredTy = std::function<bool(const TargetInstrInfo &TII, 33 const TargetSubtargetInfo &TSI, 34 const MachineInstr *FirstMI, 35 const MachineInstr &SecondMI)>; 36 37 /// Checks if the number of cluster edges between SU and its predecessors is 38 /// less than FuseLimit 39 bool hasLessThanNumFused(const SUnit &SU, unsigned FuseLimit); 40 41 /// Create an artificial edge between FirstSU and SecondSU. 42 /// Make data dependencies from the FirstSU also dependent on the SecondSU to 43 /// prevent them from being scheduled between the FirstSU and the SecondSU 44 /// and vice-versa. 45 /// Fusing more than 2 instructions is not currently supported. 46 bool fuseInstructionPair(ScheduleDAGInstrs &DAG, SUnit &FirstSU, 47 SUnit &SecondSU); 48 49 /// Create a DAG scheduling mutation to pair instructions back to back 50 /// for instructions that benefit according to the target-specific 51 /// shouldScheduleAdjacent predicate function. 52 std::unique_ptr<ScheduleDAGMutation> 53 createMacroFusionDAGMutation(ShouldSchedulePredTy shouldScheduleAdjacent); 54 55 /// Create a DAG scheduling mutation to pair branch instructions with one 56 /// of their predecessors back to back for instructions that benefit according 57 /// to the target-specific shouldScheduleAdjacent predicate function. 58 std::unique_ptr<ScheduleDAGMutation> 59 createBranchMacroFusionDAGMutation(ShouldSchedulePredTy shouldScheduleAdjacent); 60 61 } // end namespace llvm 62 63 #endif // LLVM_CODEGEN_MACROFUSION_H 64