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.
isAESPair(const MachineInstr * FirstMI,const MachineInstr & SecondMI)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.
isLiteralsPair(const MachineInstr * FirstMI,const MachineInstr & SecondMI)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.
shouldScheduleAdjacent(const TargetInstrInfo & TII,const TargetSubtargetInfo & TSI,const MachineInstr * FirstMI,const MachineInstr & SecondMI)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
createARMMacroFusionDAGMutation()65 std::unique_ptr<ScheduleDAGMutation> createARMMacroFusionDAGMutation () {
66 return createMacroFusionDAGMutation(shouldScheduleAdjacent);
67 }
68
69 } // end namespace llvm
70