1//===- GCNCreateVOPD.cpp - Create VOPD Instructions ----------------------===//
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
10/// Combine VALU pairs into VOPD instructions
11/// Only works on wave32
12/// Has register requirements, we reject creating VOPD if the requirements are
13/// not met.
14/// shouldCombineVOPD mutator in postRA machine scheduler puts candidate
15/// instructions for VOPD back-to-back
16///
17//
18//===----------------------------------------------------------------------===//
19
20#include "AMDGPU.h"
21#include "GCNSubtarget.h"
22#include "GCNVOPDUtils.h"
23#include "MCTargetDesc/AMDGPUMCTargetDesc.h"
24#include "SIInstrInfo.h"
25#include "Utils/AMDGPUBaseInfo.h"
26#include "llvm/ADT/SmallVector.h"
27#include "llvm/ADT/Statistic.h"
28#include "llvm/CodeGen/MachineBasicBlock.h"
29#include "llvm/CodeGen/MachineInstr.h"
30#include "llvm/CodeGen/MachineOperand.h"
31#include "llvm/Support/Casting.h"
32#include "llvm/Support/Debug.h"
33#include <utility>
34
35#define DEBUG_TYPE "gcn-create-vopd"
36STATISTIC(NumVOPDCreated, "Number of VOPD Insts Created.");
37
38using namespace llvm;
39
40namespace {
41
42class GCNCreateVOPD : public MachineFunctionPass {
43private:
44 class VOPDCombineInfo {
45 public:
46 VOPDCombineInfo() = default;
47 VOPDCombineInfo(MachineInstr *First, MachineInstr *Second)
48 : FirstMI(First), SecondMI(Second) {}
49
50 MachineInstr *FirstMI;
51 MachineInstr *SecondMI;
52 };
53
54public:
55 static char ID;
56 const GCNSubtarget *ST = nullptr;
57
58 GCNCreateVOPD() : MachineFunctionPass(ID) {}
59
60 void getAnalysisUsage(AnalysisUsage &AU) const override {
61 AU.setPreservesCFG();
62 MachineFunctionPass::getAnalysisUsage(AU);
63 }
64
65 StringRef getPassName() const override {
66 return "GCN Create VOPD Instructions";
67 }
68
69 bool doReplace(const SIInstrInfo *SII, VOPDCombineInfo &CI) {
70 auto *FirstMI = CI.FirstMI;
71 auto *SecondMI = CI.SecondMI;
72 unsigned Opc1 = FirstMI->getOpcode();
73 unsigned Opc2 = SecondMI->getOpcode();
74 unsigned EncodingFamily =
75 AMDGPU::getVOPDEncodingFamily(ST: SII->getSubtarget());
76 int NewOpcode =
77 AMDGPU::getVOPDFull(OpX: AMDGPU::getVOPDOpcode(Opc: Opc1),
78 OpY: AMDGPU::getVOPDOpcode(Opc: Opc2), EncodingFamily);
79 assert(NewOpcode != -1 &&
80 "Should have previously determined this as a possible VOPD\n");
81
82 auto VOPDInst = BuildMI(BB&: *FirstMI->getParent(), I: FirstMI,
83 MIMD: FirstMI->getDebugLoc(), MCID: SII->get(Opcode: NewOpcode))
84 .setMIFlags(FirstMI->getFlags() | SecondMI->getFlags());
85
86 namespace VOPD = AMDGPU::VOPD;
87 MachineInstr *MI[] = {FirstMI, SecondMI};
88 auto InstInfo =
89 AMDGPU::getVOPDInstInfo(OpX: FirstMI->getDesc(), OpY: SecondMI->getDesc());
90
91 for (auto CompIdx : VOPD::COMPONENTS) {
92 auto MCOprIdx = InstInfo[CompIdx].getIndexOfDstInMCOperands();
93 VOPDInst.add(MO: MI[CompIdx]->getOperand(i: MCOprIdx));
94 }
95
96 for (auto CompIdx : VOPD::COMPONENTS) {
97 auto CompSrcOprNum = InstInfo[CompIdx].getCompSrcOperandsNum();
98 for (unsigned CompSrcIdx = 0; CompSrcIdx < CompSrcOprNum; ++CompSrcIdx) {
99 auto MCOprIdx = InstInfo[CompIdx].getIndexOfSrcInMCOperands(CompSrcIdx);
100 VOPDInst.add(MO: MI[CompIdx]->getOperand(i: MCOprIdx));
101 }
102 }
103
104 SII->fixImplicitOperands(MI&: *VOPDInst);
105 for (auto CompIdx : VOPD::COMPONENTS)
106 VOPDInst.copyImplicitOps(OtherMI: *MI[CompIdx]);
107
108 LLVM_DEBUG(dbgs() << "VOPD Fused: " << *VOPDInst << " from\tX: "
109 << *CI.FirstMI << "\tY: " << *CI.SecondMI << "\n");
110
111 for (auto CompIdx : VOPD::COMPONENTS)
112 MI[CompIdx]->eraseFromParent();
113
114 ++NumVOPDCreated;
115 return true;
116 }
117
118 bool runOnMachineFunction(MachineFunction &MF) override {
119 if (skipFunction(F: MF.getFunction()))
120 return false;
121 ST = &MF.getSubtarget<GCNSubtarget>();
122 if (!AMDGPU::hasVOPD(STI: *ST) || !ST->isWave32())
123 return false;
124 LLVM_DEBUG(dbgs() << "CreateVOPD Pass:\n");
125
126 const SIInstrInfo *SII = ST->getInstrInfo();
127 bool Changed = false;
128
129 SmallVector<VOPDCombineInfo> ReplaceCandidates;
130
131 for (auto &MBB : MF) {
132 auto MII = MBB.begin(), E = MBB.end();
133 while (MII != E) {
134 auto *FirstMI = &*MII;
135 MII = next_nodbg(It: MII, End: MBB.end());
136 if (MII == MBB.end())
137 break;
138 if (FirstMI->isDebugInstr())
139 continue;
140 auto *SecondMI = &*MII;
141 unsigned Opc = FirstMI->getOpcode();
142 unsigned Opc2 = SecondMI->getOpcode();
143 llvm::AMDGPU::CanBeVOPD FirstCanBeVOPD = AMDGPU::getCanBeVOPD(Opc);
144 llvm::AMDGPU::CanBeVOPD SecondCanBeVOPD = AMDGPU::getCanBeVOPD(Opc: Opc2);
145 VOPDCombineInfo CI;
146
147 if (FirstCanBeVOPD.X && SecondCanBeVOPD.Y)
148 CI = VOPDCombineInfo(FirstMI, SecondMI);
149 else if (FirstCanBeVOPD.Y && SecondCanBeVOPD.X)
150 CI = VOPDCombineInfo(SecondMI, FirstMI);
151 else
152 continue;
153 // checkVOPDRegConstraints cares about program order, but doReplace
154 // cares about X-Y order in the constituted VOPD
155 if (llvm::checkVOPDRegConstraints(TII: *SII, FirstMI: *FirstMI, SecondMI: *SecondMI)) {
156 ReplaceCandidates.push_back(Elt: CI);
157 ++MII;
158 }
159 }
160 }
161 for (auto &CI : ReplaceCandidates) {
162 Changed |= doReplace(SII, CI);
163 }
164
165 return Changed;
166 }
167};
168
169} // namespace
170
171char GCNCreateVOPD::ID = 0;
172
173char &llvm::GCNCreateVOPDID = GCNCreateVOPD::ID;
174
175INITIALIZE_PASS(GCNCreateVOPD, DEBUG_TYPE, "GCN Create VOPD Instructions",
176 false, false)
177