lib/Target/ARM/ARMMacroFusion.cpp

   1 //===- ARMMacroFusion.cpp - ARM Macro Fusion ----------------------===//
   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 ARM implementation of the DAG scheduling
  10 ///  mutation to pair instructions back to back.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "ARMMacroFusion.h"
  15 #include "ARMSubtarget.h"
  16 #include "llvm/CodeGen/MacroFusion.h"
  17 #include "llvm/CodeGen/TargetInstrInfo.h"
  18
  19 namespace llvm {
  20
  21 // Fuse AES crypto encoding or decoding.
  22 static bool isAESPair(const MachineInstr *FirstMI,
  23                       const MachineInstr &SecondMI) {
  24   // Assume the 1st instr to be a wildcard if it is unspecified.
  25   switch(SecondMI.getOpcode()) {
  26   // AES encode.
  27   case ARM::AESMC :
  28     return FirstMI == nullptr || FirstMI->getOpcode() == ARM::AESE;
  29   // AES decode.
  30   case ARM::AESIMC:
  31     return FirstMI == nullptr || FirstMI->getOpcode() == ARM::AESD;
  32   }
  33
  34   return false;
  35 }
  36
  37 // Fuse literal generation.
  38 static bool isLiteralsPair(const MachineInstr *FirstMI,
  39                            const MachineInstr &SecondMI) {
  40   // Assume the 1st instr to be a wildcard if it is unspecified.
  41   if ((FirstMI == nullptr || FirstMI->getOpcode() == ARM::MOVi16) &&
  42       SecondMI.getOpcode() == ARM::MOVTi16)
  43     return true;
  44
  45   return false;
  46 }
  47
  48 /// Check if the instr pair, FirstMI and SecondMI, should be fused
  49 /// together. Given SecondMI, when FirstMI is unspecified, then check if
  50 /// SecondMI may be part of a fused pair at all.
  51 static bool shouldScheduleAdjacent(const TargetInstrInfo &TII,
  52                                    const TargetSubtargetInfo &TSI,
  53                                    const MachineInstr *FirstMI,
  54                                    const MachineInstr &SecondMI) {
  55   const ARMSubtarget &ST = static_cast<const ARMSubtarget&>(TSI);
  56
  57   if (ST.hasFuseAES() && isAESPair(FirstMI, SecondMI))
  58     return true;
  59   if (ST.hasFuseLiterals() && isLiteralsPair(FirstMI, SecondMI))
  60     return true;
  61
  62   return false;
  63 }
  64
  65 std::unique_ptr<ScheduleDAGMutation> createARMMacroFusionDAGMutation () {
  66   return createMacroFusionDAGMutation(shouldScheduleAdjacent);
  67 }
  68
  69 } // end namespace llvm