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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.
//
//===----------------------------------------------------------------------===//
// 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 "R600InstrInfo.h"
#include "R600RegisterInfo.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;
public:
R600ExpandSpecialInstrsPass(TargetMachine &tm) : MachineFunctionPass(ID),
TII (static_cast<const R600InstrInfo *>(tm.getInstrInfo())) { }
virtual bool runOnMachineFunction(MachineFunction &MF);
const char *getPassName() const {
return "R600 Expand special instructions pass";
}
};
} // End anonymous namespace
char R600ExpandSpecialInstrsPass::ID = 0;
FunctionPass *llvm::createR600ExpandSpecialInstrsPass(TargetMachine &TM) {
return new R600ExpandSpecialInstrsPass(TM);
}
bool R600ExpandSpecialInstrsPass::runOnMachineFunction(MachineFunction &MF) {
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 = llvm::next(I);
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(0).getReg();
unsigned Src0 = MI.getOperand(1).getReg();
unsigned Src1 = 0;
// Determine the correct source registers
if (!IsCube) {
Src1 = MI.getOperand(2).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;
unsigned Flags = 0;
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.
Flags |= (Chan != TRI.getHWRegChan(DstReg) ? MO_FLAG_MASK : 0);
unsigned DstBase = TRI.getHWRegIndex(DstReg);
DstReg = AMDGPU::R600_TReg32RegClass.getRegister((DstBase * 4) + Chan);
}
// Set the IsLast bit
Flags |= (Chan == 3 ? MO_FLAG_LAST : 0);
// Add the new instruction
unsigned Opcode;
if (IsCube) {
switch (MI.getOpcode()) {
case AMDGPU::CUBE_r600_pseudo:
Opcode = AMDGPU::CUBE_r600_real;
break;
case AMDGPU::CUBE_eg_pseudo:
Opcode = AMDGPU::CUBE_eg_real;
break;
default:
assert(!"Unknown CUBE instruction");
Opcode = 0;
break;
}
} else {
Opcode = MI.getOpcode();
}
MachineInstr *NewMI =
BuildMI(MBB, I, MBB.findDebugLoc(I), TII->get(Opcode), DstReg)
.addReg(Src0)
.addReg(Src1);
NewMI->setIsInsideBundle(Chan != 0);
TII->AddFlag(NewMI, 0, Flags);
}
MI.eraseFromParent();
}
}
return false;
}
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