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llvm-project/llvm/lib/Target/AMDGPU/R600ExpandSpecialInstrs.cpp

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//===-- R600ExpandSpecialInstrs.cpp - Expand special instructions ---------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
/// \file
/// Vector, Reduction, and Cube instructions need to fill the entire instruction
/// group to work correctly. This pass expands these individual instructions
/// into several instructions that will completely fill the instruction group.
//
//===----------------------------------------------------------------------===//
#include "AMDGPU.h"
#include "R600Defines.h"
#include "R600InstrInfo.h"
#include "R600MachineFunctionInfo.h"
#include "R600RegisterInfo.h"
#include "AMDGPUSubtarget.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
using namespace llvm;
namespace {
class R600ExpandSpecialInstrsPass : public MachineFunctionPass {
private:
static char ID;
const R600InstrInfo *TII;
void SetFlagInNewMI(MachineInstr *NewMI, const MachineInstr *OldMI,
unsigned Op);
public:
R600ExpandSpecialInstrsPass() : MachineFunctionPass(ID),
TII(nullptr) { }
bool runOnMachineFunction(MachineFunction &MF) override;
StringRef getPassName() const override {
return "R600 Expand special instructions pass";
}
};
} // End anonymous namespace
char R600ExpandSpecialInstrsPass::ID = 0;
FunctionPass *llvm::createR600ExpandSpecialInstrsPass() {
return new R600ExpandSpecialInstrsPass();
}
void R600ExpandSpecialInstrsPass::SetFlagInNewMI(MachineInstr *NewMI,
const MachineInstr *OldMI, unsigned Op) {
int OpIdx = TII->getOperandIdx(*OldMI, Op);
if (OpIdx > -1) {
uint64_t Val = OldMI->getOperand(OpIdx).getImm();
TII->setImmOperand(*NewMI, Op, Val);
}
}
bool R600ExpandSpecialInstrsPass::runOnMachineFunction(MachineFunction &MF) {
const R600Subtarget &ST = MF.getSubtarget<R600Subtarget>();
TII = ST.getInstrInfo();
const R600RegisterInfo &TRI = TII->getRegisterInfo();
for (MachineFunction::iterator BB = MF.begin(), BB_E = MF.end();
BB != BB_E; ++BB) {
MachineBasicBlock &MBB = *BB;
MachineBasicBlock::iterator I = MBB.begin();
while (I != MBB.end()) {
MachineInstr &MI = *I;
I = std::next(I);
// Expand LDS_*_RET instructions
if (TII->isLDSRetInstr(MI.getOpcode())) {
int DstIdx = TII->getOperandIdx(MI.getOpcode(), AMDGPU::OpName::dst);
assert(DstIdx != -1);
MachineOperand &DstOp = MI.getOperand(DstIdx);
MachineInstr *Mov = TII->buildMovInstr(&MBB, I,
DstOp.getReg(), AMDGPU::OQAP);
DstOp.setReg(AMDGPU::OQAP);
int LDSPredSelIdx = TII->getOperandIdx(MI.getOpcode(),
AMDGPU::OpName::pred_sel);
int MovPredSelIdx = TII->getOperandIdx(Mov->getOpcode(),
AMDGPU::OpName::pred_sel);
// Copy the pred_sel bit
Mov->getOperand(MovPredSelIdx).setReg(
MI.getOperand(LDSPredSelIdx).getReg());
}
switch (MI.getOpcode()) {
default: break;
// Expand PRED_X to one of the PRED_SET instructions.
case AMDGPU::PRED_X: {
uint64_t Flags = MI.getOperand(3).getImm();
// The native opcode used by PRED_X is stored as an immediate in the
// third operand.
MachineInstr *PredSet = TII->buildDefaultInstruction(MBB, I,
MI.getOperand(2).getImm(), // opcode
MI.getOperand(0).getReg(), // dst
MI.getOperand(1).getReg(), // src0
AMDGPU::ZERO); // src1
TII->addFlag(*PredSet, 0, MO_FLAG_MASK);
if (Flags & MO_FLAG_PUSH) {
TII->setImmOperand(*PredSet, AMDGPU::OpName::update_exec_mask, 1);
} else {
TII->setImmOperand(*PredSet, AMDGPU::OpName::update_pred, 1);
}
MI.eraseFromParent();
continue;
}
case AMDGPU::DOT_4: {
const R600RegisterInfo &TRI = TII->getRegisterInfo();
unsigned DstReg = MI.getOperand(0).getReg();
unsigned DstBase = TRI.getEncodingValue(DstReg) & HW_REG_MASK;
for (unsigned Chan = 0; Chan < 4; ++Chan) {
bool Mask = (Chan != TRI.getHWRegChan(DstReg));
unsigned SubDstReg =
AMDGPU::R600_TReg32RegClass.getRegister((DstBase * 4) + Chan);
MachineInstr *BMI =
TII->buildSlotOfVectorInstruction(MBB, &MI, Chan, SubDstReg);
if (Chan > 0) {
BMI->bundleWithPred();
}
if (Mask) {
TII->addFlag(*BMI, 0, MO_FLAG_MASK);
}
if (Chan != 3)
TII->addFlag(*BMI, 0, MO_FLAG_NOT_LAST);
unsigned Opcode = BMI->getOpcode();
// While not strictly necessary from hw point of view, we force
// all src operands of a dot4 inst to belong to the same slot.
unsigned Src0 = BMI->getOperand(
TII->getOperandIdx(Opcode, AMDGPU::OpName::src0))
.getReg();
unsigned Src1 = BMI->getOperand(
TII->getOperandIdx(Opcode, AMDGPU::OpName::src1))
.getReg();
(void) Src0;
(void) Src1;
if ((TRI.getEncodingValue(Src0) & 0xff) < 127 &&
(TRI.getEncodingValue(Src1) & 0xff) < 127)
assert(TRI.getHWRegChan(Src0) == TRI.getHWRegChan(Src1));
}
MI.eraseFromParent();
continue;
}
}
bool IsReduction = TII->isReductionOp(MI.getOpcode());
bool IsVector = TII->isVector(MI);
bool IsCube = TII->isCubeOp(MI.getOpcode());
if (!IsReduction && !IsVector && !IsCube) {
continue;
}
// Expand the instruction
//
// Reduction instructions:
// T0_X = DP4 T1_XYZW, T2_XYZW
// becomes:
// TO_X = DP4 T1_X, T2_X
// TO_Y (write masked) = DP4 T1_Y, T2_Y
// TO_Z (write masked) = DP4 T1_Z, T2_Z
// TO_W (write masked) = DP4 T1_W, T2_W
//
// Vector instructions:
// T0_X = MULLO_INT T1_X, T2_X
// becomes:
// T0_X = MULLO_INT T1_X, T2_X
// T0_Y (write masked) = MULLO_INT T1_X, T2_X
// T0_Z (write masked) = MULLO_INT T1_X, T2_X
// T0_W (write masked) = MULLO_INT T1_X, T2_X
//
// Cube instructions:
// T0_XYZW = CUBE T1_XYZW
// becomes:
// TO_X = CUBE T1_Z, T1_Y
// T0_Y = CUBE T1_Z, T1_X
// T0_Z = CUBE T1_X, T1_Z
// T0_W = CUBE T1_Y, T1_Z
for (unsigned Chan = 0; Chan < 4; Chan++) {
unsigned DstReg = MI.getOperand(
TII->getOperandIdx(MI, AMDGPU::OpName::dst)).getReg();
unsigned Src0 = MI.getOperand(
TII->getOperandIdx(MI, AMDGPU::OpName::src0)).getReg();
unsigned Src1 = 0;
// Determine the correct source registers
if (!IsCube) {
int Src1Idx = TII->getOperandIdx(MI, AMDGPU::OpName::src1);
if (Src1Idx != -1) {
Src1 = MI.getOperand(Src1Idx).getReg();
}
}
if (IsReduction) {
unsigned SubRegIndex = TRI.getSubRegFromChannel(Chan);
Src0 = TRI.getSubReg(Src0, SubRegIndex);
Src1 = TRI.getSubReg(Src1, SubRegIndex);
} else if (IsCube) {
static const int CubeSrcSwz[] = {2, 2, 0, 1};
unsigned SubRegIndex0 = TRI.getSubRegFromChannel(CubeSrcSwz[Chan]);
unsigned SubRegIndex1 = TRI.getSubRegFromChannel(CubeSrcSwz[3 - Chan]);
Src1 = TRI.getSubReg(Src0, SubRegIndex1);
Src0 = TRI.getSubReg(Src0, SubRegIndex0);
}
// Determine the correct destination registers;
bool Mask = false;
bool NotLast = true;
if (IsCube) {
unsigned SubRegIndex = TRI.getSubRegFromChannel(Chan);
DstReg = TRI.getSubReg(DstReg, SubRegIndex);
} else {
// Mask the write if the original instruction does not write to
// the current Channel.
Mask = (Chan != TRI.getHWRegChan(DstReg));
unsigned DstBase = TRI.getEncodingValue(DstReg) & HW_REG_MASK;
DstReg = AMDGPU::R600_TReg32RegClass.getRegister((DstBase * 4) + Chan);
}
// Set the IsLast bit
NotLast = (Chan != 3 );
// Add the new instruction
unsigned Opcode = MI.getOpcode();
switch (Opcode) {
case AMDGPU::CUBE_r600_pseudo:
Opcode = AMDGPU::CUBE_r600_real;
break;
case AMDGPU::CUBE_eg_pseudo:
Opcode = AMDGPU::CUBE_eg_real;
break;
default:
break;
}
MachineInstr *NewMI =
TII->buildDefaultInstruction(MBB, I, Opcode, DstReg, Src0, Src1);
if (Chan != 0)
NewMI->bundleWithPred();
if (Mask) {
TII->addFlag(*NewMI, 0, MO_FLAG_MASK);
}
if (NotLast) {
TII->addFlag(*NewMI, 0, MO_FLAG_NOT_LAST);
}
SetFlagInNewMI(NewMI, &MI, AMDGPU::OpName::clamp);
SetFlagInNewMI(NewMI, &MI, AMDGPU::OpName::literal);
SetFlagInNewMI(NewMI, &MI, AMDGPU::OpName::src0_abs);
SetFlagInNewMI(NewMI, &MI, AMDGPU::OpName::src1_abs);
SetFlagInNewMI(NewMI, &MI, AMDGPU::OpName::src0_neg);
SetFlagInNewMI(NewMI, &MI, AMDGPU::OpName::src1_neg);
}
MI.eraseFromParent();
}
}
return false;
}
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