1 //===-- X86LowerTileCopy.cpp - Expand Tile Copy 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 // This file defines the pass which lower AMX tile copy instructions. Since
10 // there is no tile copy instruction, we need store tile register to stack
11 // and load from stack to another tile register. We need extra GR to hold
12 // the stride, and we need stack slot to hold the tile data register.
13 // We would run this pass after copy propagation, so that we don't miss copy
14 // optimization. And we would run this pass before prolog/epilog insertion,
15 // so that we can allocate stack slot.
16 //
17 //===----------------------------------------------------------------------===//
18
19 #include "X86.h"
20 #include "X86InstrBuilder.h"
21 #include "X86InstrInfo.h"
22 #include "X86Subtarget.h"
23 #include "llvm/CodeGen/MachineBasicBlock.h"
24 #include "llvm/CodeGen/MachineFrameInfo.h"
25 #include "llvm/CodeGen/MachineFunction.h"
26 #include "llvm/CodeGen/MachineFunctionPass.h"
27 #include "llvm/CodeGen/MachineInstr.h"
28 #include "llvm/CodeGen/MachineInstrBuilder.h"
29 #include "llvm/CodeGen/MachineOperand.h"
30 #include "llvm/CodeGen/Passes.h"
31 #include "llvm/IR/DebugLoc.h"
32 #include "llvm/InitializePasses.h"
33 #include "llvm/Support/Debug.h"
34
35 using namespace llvm;
36
37 #define DEBUG_TYPE "x86-lower-tile-copy"
38
39 namespace {
40
41 class X86LowerTileCopy : public MachineFunctionPass {
42 public:
43 static char ID;
44
X86LowerTileCopy()45 X86LowerTileCopy() : MachineFunctionPass(ID) {}
46
47 void getAnalysisUsage(AnalysisUsage &AU) const override;
48
49 bool runOnMachineFunction(MachineFunction &MF) override;
50
getPassName() const51 StringRef getPassName() const override { return "X86 Lower Tile Copy"; }
52 };
53
54 } // namespace
55
56 char X86LowerTileCopy::ID = 0;
57
58 INITIALIZE_PASS_BEGIN(X86LowerTileCopy, "lowertilecopy", "Tile Copy Lowering",
59 false, false)
60 INITIALIZE_PASS_END(X86LowerTileCopy, "lowertilecopy", "Tile Copy Lowering",
61 false, false)
62
getAnalysisUsage(AnalysisUsage & AU) const63 void X86LowerTileCopy::getAnalysisUsage(AnalysisUsage &AU) const {
64 AU.setPreservesAll();
65 MachineFunctionPass::getAnalysisUsage(AU);
66 }
67
createX86LowerTileCopyPass()68 FunctionPass *llvm::createX86LowerTileCopyPass() {
69 return new X86LowerTileCopy();
70 }
71
runOnMachineFunction(MachineFunction & MF)72 bool X86LowerTileCopy::runOnMachineFunction(MachineFunction &MF) {
73 const X86Subtarget &ST = MF.getSubtarget<X86Subtarget>();
74 const X86InstrInfo *TII = ST.getInstrInfo();
75 bool Changed = false;
76
77 for (MachineBasicBlock &MBB : MF) {
78 for (MachineInstr &MI : llvm::make_early_inc_range(MBB)) {
79 if (!MI.isCopy())
80 continue;
81 MachineOperand &DstMO = MI.getOperand(0);
82 MachineOperand &SrcMO = MI.getOperand(1);
83 Register SrcReg = SrcMO.getReg();
84 Register DstReg = DstMO.getReg();
85 if (!X86::TILERegClass.contains(DstReg, SrcReg))
86 continue;
87
88 const TargetRegisterInfo *TRI = ST.getRegisterInfo();
89 // Allocate stack slot for tile register
90 unsigned Size = TRI->getSpillSize(X86::TILERegClass);
91 Align Alignment = TRI->getSpillAlign(X86::TILERegClass);
92 int TileSS = MF.getFrameInfo().CreateSpillStackObject(Size, Alignment);
93 // Allocate stack slot for stride register
94 Size = TRI->getSpillSize(X86::GR64RegClass);
95 Alignment = TRI->getSpillAlign(X86::GR64RegClass);
96 int StrideSS = MF.getFrameInfo().CreateSpillStackObject(Size, Alignment);
97
98 // TODO: Pick a killed regiter to avoid save/reload. There is problem
99 // to get live interval in this stage.
100 Register GR64Cand = X86::RAX;
101
102 const DebugLoc &DL = MI.getDebugLoc();
103 // mov %rax (%sp)
104 BuildMI(MBB, MI, DL, TII->get(X86::IMPLICIT_DEF), GR64Cand);
105 addFrameReference(BuildMI(MBB, MI, DL, TII->get(X86::MOV64mr)), StrideSS)
106 .addReg(GR64Cand);
107 // mov 64 %rax
108 BuildMI(MBB, MI, DL, TII->get(X86::MOV64ri), GR64Cand).addImm(64);
109 // tilestored %tmm, (%sp, %idx)
110 unsigned Opc = X86::TILESTORED;
111 MachineInstr *NewMI =
112 addFrameReference(BuildMI(MBB, MI, DL, TII->get(Opc)), TileSS)
113 .addReg(SrcReg, getKillRegState(SrcMO.isKill()));
114 MachineOperand &MO = NewMI->getOperand(2);
115 MO.setReg(GR64Cand);
116 MO.setIsKill(true);
117 // tileloadd (%sp, %idx), %tmm
118 Opc = X86::TILELOADD;
119 NewMI = addFrameReference(BuildMI(MBB, MI, DL, TII->get(Opc), DstReg),
120 TileSS);
121 // restore %rax
122 // mov (%sp) %rax
123 addFrameReference(BuildMI(MBB, MI, DL, TII->get(X86::MOV64rm), GR64Cand),
124 StrideSS);
125 MI.eraseFromParent();
126 Changed = true;
127 }
128 }
129 return Changed;
130 }
131