1 //===--- AMDGPUMacroFusion.cpp - AMDGPU 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 AMDGPU implementation of the DAG scheduling
11 /// mutation to pair instructions back to back.
12 //
13 //===----------------------------------------------------------------------===//
14
15 #include "AMDGPUMacroFusion.h"
16 #include "AMDGPUSubtarget.h"
17 #include "SIInstrInfo.h"
18 #include "MCTargetDesc/AMDGPUMCTargetDesc.h"
19
20 #include "llvm/CodeGen/MacroFusion.h"
21
22 using namespace llvm;
23
24 namespace {
25
26 /// Check if the instr pair, FirstMI and SecondMI, should be fused
27 /// together. Given SecondMI, when FirstMI is unspecified, then check if
28 /// SecondMI may be part of a fused pair at all.
shouldScheduleAdjacent(const TargetInstrInfo & TII_,const TargetSubtargetInfo & TSI,const MachineInstr * FirstMI,const MachineInstr & SecondMI)29 static bool shouldScheduleAdjacent(const TargetInstrInfo &TII_,
30 const TargetSubtargetInfo &TSI,
31 const MachineInstr *FirstMI,
32 const MachineInstr &SecondMI) {
33 const SIInstrInfo &TII = static_cast<const SIInstrInfo&>(TII_);
34
35 switch (SecondMI.getOpcode()) {
36 case AMDGPU::V_ADDC_U32_e64:
37 case AMDGPU::V_SUBB_U32_e64:
38 case AMDGPU::V_CNDMASK_B32_e64: {
39 // Try to cluster defs of condition registers to their uses. This improves
40 // the chance VCC will be available which will allow shrinking to VOP2
41 // encodings.
42 if (!FirstMI)
43 return true;
44
45 const MachineOperand *Src2 = TII.getNamedOperand(SecondMI,
46 AMDGPU::OpName::src2);
47 return FirstMI->definesRegister(Src2->getReg());
48 }
49 default:
50 return false;
51 }
52
53 return false;
54 }
55
56 } // end namespace
57
58
59 namespace llvm {
60
createAMDGPUMacroFusionDAGMutation()61 std::unique_ptr<ScheduleDAGMutation> createAMDGPUMacroFusionDAGMutation () {
62 return createMacroFusionDAGMutation(shouldScheduleAdjacent);
63 }
64
65 } // end namespace llvm
66