//===-- X86PreTileConfig.cpp - Tile Register Configure---------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
/// \file Pass to pre-config the shape of AMX register
/// AMX register need to be configured before use. The shape of AMX register
/// is encoded in the 1st and 2nd machine operand of AMX pseudo instructions.
/// The pldtilecfg is to config tile registers. It should dominator all AMX
/// instructions. The pldtilecfg produce a virtual cfg register and the cfg
/// register is used by all AMX instructions.
/// This pass is to find the common dominator of all AMX instructions and
/// insert the pldtilecfg instruction. Besides the cfg register that pldtilecfg
/// produces is inserted as the last operand of each AMX instruction. We use
/// this scheme to model the def-use relationship between AMX config instruction
/// and other AMX instructions. Below is an example.
///
/// ----B1----
/// / \
/// / \
/// B2 B3
/// %1:tile = PTILELOADDV %2:tile = PTILELOADDV
///
/// is transformed to
///
/// B1
/// %25:tilecfg = PLDTILECFG
/// / \
/// / \
/// %1:tile = PTILELOADDV %25 %2:tile = PTILELOADDV %25
//
//===----------------------------------------------------------------------===//
#include "X86.h"
#include "X86InstrBuilder.h"
#include "X86RegisterInfo.h"
#include "X86Subtarget.h"
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/CodeGen/TargetInstrInfo.h"
#include "llvm/CodeGen/TargetRegisterInfo.h"
#include "llvm/CodeGen/TileShapeInfo.h"
#include "llvm/InitializePasses.h"
using namespace llvm;
#define DEBUG_TYPE "tile-pre-config"
namespace {
class X86PreTileConfig : public MachineFunctionPass {
// context
MachineFunction *MF = nullptr;
const X86Subtarget *ST = nullptr;
const TargetRegisterInfo *TRI;
const TargetInstrInfo *TII;
MachineDominatorTree *DomTree = nullptr;
MachineRegisterInfo *MRI = nullptr;
MachineInstr *getTileConfigPoint();
public:
X86PreTileConfig() : MachineFunctionPass(ID) {}
/// Return the pass name.
StringRef getPassName() const override {
return "Tile Register Pre-configure";
}
/// X86PreTileConfig analysis usage.
void getAnalysisUsage(AnalysisUsage &AU) const override;
/// Perform register allocation.
bool runOnMachineFunction(MachineFunction &mf) override;
static char ID;
};
} // end anonymous namespace
char X86PreTileConfig::ID = 0;
INITIALIZE_PASS_BEGIN(X86PreTileConfig, "tilepreconfig",
"Tile Register Configure", false, false)
INITIALIZE_PASS_DEPENDENCY(MachineDominatorTree)
INITIALIZE_PASS_END(X86PreTileConfig, "tilepreconfig",
"Tile Register Configure", false, false)
void X86PreTileConfig::getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
AU.addRequired<MachineDominatorTree>();
MachineFunctionPass::getAnalysisUsage(AU);
}
static Register buildConfigMI(MachineBasicBlock::iterator MI, int FrameIdx,
const TargetInstrInfo *TII,
MachineRegisterInfo *MRI,
const X86Subtarget *ST) {
auto *MBB = MI->getParent();
// FIXME: AMX should assume AVX512 enabled.
if (ST->hasAVX512()) {
// Zero stack slot.
Register Zmm = MRI->createVirtualRegister(&X86::VR512RegClass);
BuildMI(*MBB, MI, DebugLoc(), TII->get(X86::VPXORDZrr), Zmm)
.addReg(Zmm, RegState::Undef)
.addReg(Zmm, RegState::Undef);
addFrameReference(BuildMI(*MBB, MI, DebugLoc(), TII->get(X86::VMOVUPSZmr)),
FrameIdx)
.addReg(Zmm);
}
// build psuedo ldtilecfg
Register VReg = MRI->createVirtualRegister(&X86::TILECFGRegClass);
addFrameReference(
BuildMI(*MBB, MI, DebugLoc(), TII->get(X86::PLDTILECFG), VReg), FrameIdx);
return VReg;
}
static ShapeT getShape(const MachineInstr &MI, MachineRegisterInfo *MRI) {
unsigned Opcode = MI.getOpcode();
switch (Opcode) {
default:
llvm_unreachable("Unexpected machine instruction on tile");
case X86::PTILELOADDV:
case X86::PTDPBSSDV:
case X86::PTILEZEROV:
MachineOperand &MO1 = const_cast<MachineOperand &>(MI.getOperand(1));
MachineOperand &MO2 = const_cast<MachineOperand &>(MI.getOperand(2));
ShapeT Shape(&MO1, &MO2, MRI);
return Shape;
}
}
MachineInstr *X86PreTileConfig::getTileConfigPoint() {
DenseMap<Register, ShapeT> PhysShapeInfo;
MachineBasicBlock *MBB = nullptr;
DenseSet<const MachineInstr *> MIs;
for (unsigned i = 0, e = MRI->getNumVirtRegs(); i != e; ++i) {
Register VirtReg = Register::index2VirtReg(i);
if (MRI->reg_nodbg_empty(VirtReg))
continue;
const TargetRegisterClass &RC = *MRI->getRegClass(VirtReg);
if (RC.getID() != X86::TILERegClassID)
continue;
// Find the common dominator for all MI that define tile register.
for (const MachineOperand &MO : MRI->def_operands(VirtReg)) {
if (MO.isUndef())
continue;
const auto *MI = MO.getParent();
// PHI or IMPLICIT_DEF instructiion.
// There must be a input tile before PHI instruction.
if (MI->isTransient())
continue;
if (!MBB)
MBB = const_cast<MachineBasicBlock *>(MI->getParent());
MBB = DomTree->findNearestCommonDominator(
MBB, const_cast<MachineBasicBlock *>(MI->getParent()));
// Collect the instructions that define shape.
ShapeT Shape = getShape(*MI, MRI);
std::array<MachineOperand *, 2> ShapeMOs = {Shape.getRow(),
Shape.getCol()};
for (auto *ShapeMO : ShapeMOs) {
Register ShapeReg = ShapeMO->getReg();
for (const MachineOperand &MO : MRI->def_operands(ShapeReg)) {
const auto *ShapeMI = MO.getParent();
MIs.insert(ShapeMI);
}
}
}
}
if (!MBB)
return nullptr;
// This pass is before the pass of eliminating PHI node, so it
// is in SSA form.
assert(MRI->isSSA() && "Not SSA form in pre-tile config");
// Shape def should dominate tile config MBB.
// def s s1 s2
// / \ \ /
// / \ \ /
// conf s3=phi(s1,s2)
// |
// c
//
for (const auto *MI : MIs) {
const MachineBasicBlock *ShapeMBB = MI->getParent();
if (DomTree->dominates(ShapeMBB, MBB))
continue;
if (MI->isMoveImmediate())
continue;
report_fatal_error(MF->getName() + ": Failed to config tile register, "
"please define the shape earlier");
}
// ldtilecfg should be inserted after the MI that define the shape.
MachineBasicBlock::reverse_instr_iterator I, E;
for (I = MBB->instr_rbegin(), E = MBB->instr_rend(); I != E; ++I) {
auto *MI = &*I;
if (MIs.count(MI) && (!MI->isMoveImmediate()))
break;
}
MachineBasicBlock::iterator MII;
if (I == E)
MII = MBB->getFirstNonPHI();
else {
MII = MachineBasicBlock::iterator(&*I);
MII++;
}
return &*MII;
}
static void addTileCFGUse(MachineFunction &MF, Register CFG) {
for (MachineBasicBlock &MBB : MF) {
// Traverse the basic block.
for (MachineInstr &MI : MBB) {
unsigned Opcode = MI.getOpcode();
switch (Opcode) {
default:
break;
case X86::PTILELOADDV:
case X86::PTILESTOREDV:
case X86::PTDPBSSDV:
case X86::PTILEZEROV:
unsigned NumOperands = MI.getNumOperands();
MI.RemoveOperand(NumOperands - 1);
MI.addOperand(MF, MachineOperand::CreateReg(CFG, false));
break;
}
}
}
}
bool X86PreTileConfig::runOnMachineFunction(MachineFunction &mf) {
MF = &mf;
MRI = &mf.getRegInfo();
ST = &mf.getSubtarget<X86Subtarget>();
TRI = ST->getRegisterInfo();
TII = mf.getSubtarget().getInstrInfo();
DomTree = &getAnalysis<MachineDominatorTree>();
MachineInstr *MI = getTileConfigPoint();
if (!MI)
return false;
unsigned Size = ST->getTileConfigSize();
Align Alignment = ST->getTileConfigAlignment();
int SS = mf.getFrameInfo().CreateStackObject(Size, Alignment, false);
Register CFG = buildConfigMI(MI, SS, TII, MRI, ST);
addTileCFGUse(mf, CFG);
return true;
}
FunctionPass *llvm::createX86PreTileConfigPass() {
return new X86PreTileConfig();
}