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//===-- X86LowerTileCopy.cpp - Expand Tile Copy Instructions---------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file defines the pass which lower AMX tile copy instructions. Since
// there is no tile copy instruction, we need store tile register to stack
// and load from stack to another tile register. We need extra GR to hold
// the stride, and we need stack slot to hold the tile data register.
// We would run this pass after copy propagation, so that we don't miss copy
// optimization. And we would run this pass before prolog/epilog insertion,
// so that we can allocate stack slot.
//
//===----------------------------------------------------------------------===//
#include "X86.h"
#include "X86InstrBuilder.h"
#include "X86InstrInfo.h"
#include "X86MachineFunctionInfo.h"
#include "X86Subtarget.h"
#include "llvm/CodeGen/LiveRegUnits.h"
#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineOperand.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/IR/DebugLoc.h"
#include "llvm/InitializePasses.h"
#include "llvm/Support/Debug.h"
using namespace llvm;
#define DEBUG_TYPE "x86-lower-tile-copy"
namespace {
class X86LowerTileCopy : public MachineFunctionPass {
public:
static char ID;
X86LowerTileCopy() : MachineFunctionPass(ID) {}
void getAnalysisUsage(AnalysisUsage &AU) const override;
bool runOnMachineFunction(MachineFunction &MF) override;
StringRef getPassName() const override { return "X86 Lower Tile Copy"; }
};
} // namespace
char X86LowerTileCopy::ID = 0;
INITIALIZE_PASS_BEGIN(X86LowerTileCopy, "lowertilecopy", "Tile Copy Lowering",
false, false)
INITIALIZE_PASS_END(X86LowerTileCopy, "lowertilecopy", "Tile Copy Lowering",
false, false)
void X86LowerTileCopy::getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
MachineFunctionPass::getAnalysisUsage(AU);
}
FunctionPass *llvm::createX86LowerTileCopyPass() {
return new X86LowerTileCopy();
}
bool X86LowerTileCopy::runOnMachineFunction(MachineFunction &MF) {
X86MachineFunctionInfo *FuncInfo = MF.getInfo<X86MachineFunctionInfo>();
if (FuncInfo->getAMXProgModel() != AMXProgModelEnum::ManagedRA)
return false;
const X86Subtarget &ST = MF.getSubtarget<X86Subtarget>();
const X86InstrInfo *TII = ST.getInstrInfo();
const TargetRegisterInfo *TRI = ST.getRegisterInfo();
BitVector GR64Regs =
TRI->getAllocatableSet(MF, TRI->getRegClass(X86::GR64RegClassID));
BitVector TILERegs =
TRI->getAllocatableSet(MF, TRI->getRegClass(X86::TILERegClassID));
bool Changed = false;
for (MachineBasicBlock &MBB : MF) {
LiveRegUnits UsedRegs(*TRI);
UsedRegs.addLiveOuts(MBB);
for (MachineInstr &MI : llvm::make_early_inc_range(reverse(MBB))) {
UsedRegs.stepBackward(MI);
if (!MI.isCopy())
continue;
MachineOperand &DstMO = MI.getOperand(0);
MachineOperand &SrcMO = MI.getOperand(1);
Register SrcReg = SrcMO.getReg();
Register DstReg = DstMO.getReg();
if (!X86::TILERegClass.contains(DstReg, SrcReg))
continue;
// Allocate stack slot for tile register
unsigned Size = TRI->getSpillSize(X86::TILERegClass);
Align Alignment = TRI->getSpillAlign(X86::TILERegClass);
int TileSS = MF.getFrameInfo().CreateSpillStackObject(Size, Alignment);
int StrideSS = 0;
// Pick a killed register to avoid a save/reload.
Register GR64Cand = X86::NoRegister;
for (auto RegT : GR64Regs.set_bits()) {
if (UsedRegs.available(RegT)) {
GR64Cand = RegT;
break;
}
}
const DebugLoc &DL = MI.getDebugLoc();
if (GR64Cand) {
// mov 64 %reg
BuildMI(MBB, MI, DL, TII->get(X86::MOV64ri), GR64Cand).addImm(64);
} else {
// No available register? Save RAX and reload it after use.
// Allocate stack slot for stride register
Size = TRI->getSpillSize(X86::GR64RegClass);
Alignment = TRI->getSpillAlign(X86::GR64RegClass);
StrideSS = MF.getFrameInfo().CreateSpillStackObject(Size, Alignment);
// mov %reg (%sp)
addFrameReference(BuildMI(MBB, MI, DL, TII->get(X86::MOV64mr)),
StrideSS)
.addReg(X86::RAX);
// mov 64 %reg
BuildMI(MBB, MI, DL, TII->get(X86::MOV64ri), X86::RAX).addImm(64);
}
// tilestored %tmm, (%sp, %idx)
#define GET_EGPR_IF_ENABLED(OPC) (ST.hasEGPR() ? OPC##_EVEX : OPC)
unsigned Opc = GET_EGPR_IF_ENABLED(X86::TILESTORED);
MachineInstr *NewMI =
addFrameReference(BuildMI(MBB, MI, DL, TII->get(Opc)), TileSS)
.addReg(SrcReg, getKillRegState(SrcMO.isKill()));
MachineOperand &MO = NewMI->getOperand(2);
MO.setReg(GR64Cand ? GR64Cand : X86::RAX);
MO.setIsKill(true);
// tileloadd (%sp, %idx), %tmm
Opc = GET_EGPR_IF_ENABLED(X86::TILELOADD);
#undef GET_EGPR_IF_ENABLED
NewMI = addFrameReference(BuildMI(MBB, MI, DL, TII->get(Opc), DstReg),
TileSS);
if (!GR64Cand) {
// restore %rax
// mov (%sp) %rax
addFrameReference(
BuildMI(MBB, MI, DL, TII->get(X86::MOV64rm), X86::RAX), StrideSS);
}
MI.eraseFromParent();
Changed = true;
}
}
return Changed;
}
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