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
70