LLVM  8.0.0svn
ARMMacroFusion.cpp
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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"
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  unsigned FirstOpcode =
27  FirstMI ? FirstMI->getOpcode()
28  : static_cast<unsigned>(ARM::INSTRUCTION_LIST_END);
29  unsigned SecondOpcode = SecondMI.getOpcode();
30 
31  switch(SecondOpcode) {
32  // AES encode.
33  case ARM::AESMC :
34  return FirstOpcode == ARM::AESE ||
35  FirstOpcode == ARM::INSTRUCTION_LIST_END;
36  // AES decode.
37  case ARM::AESIMC:
38  return FirstOpcode == ARM::AESD ||
39  FirstOpcode == ARM::INSTRUCTION_LIST_END;
40  }
41 
42  return false;
43 }
44 
45 // Fuse literal generation.
46 static bool isLiteralsPair(const MachineInstr *FirstMI,
47  const MachineInstr &SecondMI) {
48  // Assume the 1st instr to be a wildcard if it is unspecified.
49  unsigned FirstOpcode =
50  FirstMI ? FirstMI->getOpcode()
51  : static_cast<unsigned>(ARM::INSTRUCTION_LIST_END);
52  unsigned SecondOpcode = SecondMI.getOpcode();
53 
54  // 32 bit immediate.
55  if ((FirstOpcode == ARM::INSTRUCTION_LIST_END ||
56  FirstOpcode == ARM::MOVi16) &&
57  SecondOpcode == ARM::MOVTi16)
58  return true;
59 
60  return false;
61 }
62 
63 /// Check if the instr pair, FirstMI and SecondMI, should be fused
64 /// together. Given SecondMI, when FirstMI is unspecified, then check if
65 /// SecondMI may be part of a fused pair at all.
67  const TargetSubtargetInfo &TSI,
68  const MachineInstr *FirstMI,
69  const MachineInstr &SecondMI) {
70  const ARMSubtarget &ST = static_cast<const ARMSubtarget&>(TSI);
71 
72  if (ST.hasFuseAES() && isAESPair(FirstMI, SecondMI))
73  return true;
74  if (ST.hasFuseLiterals() && isLiteralsPair(FirstMI, SecondMI))
75  return true;
76 
77  return false;
78 }
79 
80 std::unique_ptr<ScheduleDAGMutation> createARMMacroFusionDAGMutation () {
82 }
83 
84 } // end namespace llvm
Compute iterated dominance frontiers using a linear time algorithm.
Definition: AllocatorList.h:24
bool hasFuseAES() const
Definition: ARMSubtarget.h:633
static bool isAESPair(const MachineInstr *FirstMI, const MachineInstr &SecondMI)
const HexagonInstrInfo * TII
unsigned getOpcode() const
Returns the opcode of this MachineInstr.
Definition: MachineInstr.h:409
std::unique_ptr< ScheduleDAGMutation > createMacroFusionDAGMutation(ShouldSchedulePredTy shouldScheduleAdjacent)
Create a DAG scheduling mutation to pair instructions back to back for instructions that benefit acco...
bool hasFuseLiterals() const
Definition: ARMSubtarget.h:634
std::unique_ptr< ScheduleDAGMutation > createARMMacroFusionDAGMutation()
Note that you have to add: DAG.addMutation(createARMMacroFusionDAGMutation()); to ARMPassConfig::crea...
TargetInstrInfo - Interface to description of machine instruction set.
static bool isLiteralsPair(const MachineInstr *FirstMI, const MachineInstr &SecondMI)
static bool shouldScheduleAdjacent(const TargetInstrInfo &TII, const TargetSubtargetInfo &TSI, const MachineInstr *FirstMI, const MachineInstr &SecondMI)
Check if the instr pair, FirstMI and SecondMI, should be fused together.
TargetSubtargetInfo - Generic base class for all target subtargets.
Representation of each machine instruction.
Definition: MachineInstr.h:64