1 //===- ARMMacroFusion.cpp - ARM Macro Fusion ----------------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 /// \file This file contains the ARM implementation of the DAG scheduling
11 ///  mutation to pair instructions back to back.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "ARMMacroFusion.h"
16 #include "ARMSubtarget.h"
17 #include "llvm/CodeGen/MacroFusion.h"
18 #include "llvm/CodeGen/TargetInstrInfo.h"
19 
20 namespace llvm {
21 
22 // Fuse AES crypto encoding or decoding.
23 static bool isAESPair(const MachineInstr *FirstMI,
24                       const MachineInstr &SecondMI) {
25   // Assume the 1st instr to be a wildcard if it is unspecified.
26   switch(SecondMI.getOpcode()) {
27   // AES encode.
28   case ARM::AESMC :
29     return FirstMI == nullptr || FirstMI->getOpcode() == ARM::AESE;
30   // AES decode.
31   case ARM::AESIMC:
32     return FirstMI == nullptr || FirstMI->getOpcode() == ARM::AESD;
33   }
34 
35   return false;
36 }
37 
38 // Fuse literal generation.
39 static bool isLiteralsPair(const MachineInstr *FirstMI,
40                            const MachineInstr &SecondMI) {
41   // Assume the 1st instr to be a wildcard if it is unspecified.
42   if ((FirstMI == nullptr || FirstMI->getOpcode() == ARM::MOVi16) &&
43       SecondMI.getOpcode() == ARM::MOVTi16)
44     return true;
45 
46   return false;
47 }
48 
49 /// Check if the instr pair, FirstMI and SecondMI, should be fused
50 /// together. Given SecondMI, when FirstMI is unspecified, then check if
51 /// SecondMI may be part of a fused pair at all.
52 static bool shouldScheduleAdjacent(const TargetInstrInfo &TII,
53                                    const TargetSubtargetInfo &TSI,
54                                    const MachineInstr *FirstMI,
55                                    const MachineInstr &SecondMI) {
56   const ARMSubtarget &ST = static_cast<const ARMSubtarget&>(TSI);
57 
58   if (ST.hasFuseAES() && isAESPair(FirstMI, SecondMI))
59     return true;
60   if (ST.hasFuseLiterals() && isLiteralsPair(FirstMI, SecondMI))
61     return true;
62 
63   return false;
64 }
65 
66 std::unique_ptr<ScheduleDAGMutation> createARMMacroFusionDAGMutation () {
67   return createMacroFusionDAGMutation(shouldScheduleAdjacent);
68 }
69 
70 } // end namespace llvm
71