llvm-6502/lib/Target/R600/R600Packetizer.cpp
2013-06-03 15:56:12 +00:00

329 lines
10 KiB
C++

//===----- R600Packetizer.cpp - VLIW packetizer ---------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
/// \file
/// This pass implements instructions packetization for R600. It unsets isLast
/// bit of instructions inside a bundle and substitutes src register with
/// PreviousVector when applicable.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "packets"
#include "llvm/Support/Debug.h"
#include "AMDGPU.h"
#include "R600InstrInfo.h"
#include "llvm/CodeGen/DFAPacketizer.h"
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineLoopInfo.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/CodeGen/ScheduleDAG.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
namespace {
class R600Packetizer : public MachineFunctionPass {
public:
static char ID;
R600Packetizer(const TargetMachine &TM) : MachineFunctionPass(ID) {}
void getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesCFG();
AU.addRequired<MachineDominatorTree>();
AU.addPreserved<MachineDominatorTree>();
AU.addRequired<MachineLoopInfo>();
AU.addPreserved<MachineLoopInfo>();
MachineFunctionPass::getAnalysisUsage(AU);
}
const char *getPassName() const {
return "R600 Packetizer";
}
bool runOnMachineFunction(MachineFunction &Fn);
};
char R600Packetizer::ID = 0;
class R600PacketizerList : public VLIWPacketizerList {
private:
const R600InstrInfo *TII;
const R600RegisterInfo &TRI;
unsigned getSlot(const MachineInstr *MI) const {
return TRI.getHWRegChan(MI->getOperand(0).getReg());
}
/// \returns register to PV chan mapping for bundle/single instructions that
/// immediatly precedes I.
DenseMap<unsigned, unsigned> getPreviousVector(MachineBasicBlock::iterator I)
const {
DenseMap<unsigned, unsigned> Result;
I--;
if (!TII->isALUInstr(I->getOpcode()) && !I->isBundle())
return Result;
MachineBasicBlock::instr_iterator BI = I.getInstrIterator();
if (I->isBundle())
BI++;
do {
if (TII->isPredicated(BI))
continue;
if (TII->isTransOnly(BI))
continue;
int OperandIdx = TII->getOperandIdx(BI->getOpcode(), R600Operands::WRITE);
if (OperandIdx > -1 && BI->getOperand(OperandIdx).getImm() == 0)
continue;
unsigned Dst = BI->getOperand(0).getReg();
if (BI->getOpcode() == AMDGPU::DOT4_r600 ||
BI->getOpcode() == AMDGPU::DOT4_eg) {
Result[Dst] = AMDGPU::PV_X;
continue;
}
unsigned PVReg = 0;
switch (TRI.getHWRegChan(Dst)) {
case 0:
PVReg = AMDGPU::PV_X;
break;
case 1:
PVReg = AMDGPU::PV_Y;
break;
case 2:
PVReg = AMDGPU::PV_Z;
break;
case 3:
PVReg = AMDGPU::PV_W;
break;
default:
llvm_unreachable("Invalid Chan");
}
Result[Dst] = PVReg;
} while ((++BI)->isBundledWithPred());
return Result;
}
void substitutePV(MachineInstr *MI, const DenseMap<unsigned, unsigned> &PVs)
const {
R600Operands::Ops Ops[] = {
R600Operands::SRC0,
R600Operands::SRC1,
R600Operands::SRC2
};
for (unsigned i = 0; i < 3; i++) {
int OperandIdx = TII->getOperandIdx(MI->getOpcode(), Ops[i]);
if (OperandIdx < 0)
continue;
unsigned Src = MI->getOperand(OperandIdx).getReg();
const DenseMap<unsigned, unsigned>::const_iterator It = PVs.find(Src);
if (It != PVs.end())
MI->getOperand(OperandIdx).setReg(It->second);
}
}
public:
// Ctor.
R600PacketizerList(MachineFunction &MF, MachineLoopInfo &MLI,
MachineDominatorTree &MDT)
: VLIWPacketizerList(MF, MLI, MDT, true),
TII (static_cast<const R600InstrInfo *>(MF.getTarget().getInstrInfo())),
TRI(TII->getRegisterInfo()) { }
// initPacketizerState - initialize some internal flags.
void initPacketizerState() { }
// ignorePseudoInstruction - Ignore bundling of pseudo instructions.
bool ignorePseudoInstruction(MachineInstr *MI, MachineBasicBlock *MBB) {
return false;
}
// isSoloInstruction - return true if instruction MI can not be packetized
// with any other instruction, which means that MI itself is a packet.
bool isSoloInstruction(MachineInstr *MI) {
if (TII->isVector(*MI))
return true;
if (!TII->isALUInstr(MI->getOpcode()))
return true;
if (TII->get(MI->getOpcode()).TSFlags & R600_InstFlag::TRANS_ONLY)
return true;
if (TII->isTransOnly(MI))
return true;
return false;
}
// isLegalToPacketizeTogether - Is it legal to packetize SUI and SUJ
// together.
bool isLegalToPacketizeTogether(SUnit *SUI, SUnit *SUJ) {
MachineInstr *MII = SUI->getInstr(), *MIJ = SUJ->getInstr();
if (getSlot(MII) <= getSlot(MIJ))
return false;
// Does MII and MIJ share the same pred_sel ?
int OpI = TII->getOperandIdx(MII->getOpcode(), R600Operands::PRED_SEL),
OpJ = TII->getOperandIdx(MIJ->getOpcode(), R600Operands::PRED_SEL);
unsigned PredI = (OpI > -1)?MII->getOperand(OpI).getReg():0,
PredJ = (OpJ > -1)?MIJ->getOperand(OpJ).getReg():0;
if (PredI != PredJ)
return false;
if (SUJ->isSucc(SUI)) {
for (unsigned i = 0, e = SUJ->Succs.size(); i < e; ++i) {
const SDep &Dep = SUJ->Succs[i];
if (Dep.getSUnit() != SUI)
continue;
if (Dep.getKind() == SDep::Anti)
continue;
if (Dep.getKind() == SDep::Output)
if (MII->getOperand(0).getReg() != MIJ->getOperand(0).getReg())
continue;
return false;
}
}
return true;
}
// isLegalToPruneDependencies - Is it legal to prune dependece between SUI
// and SUJ.
bool isLegalToPruneDependencies(SUnit *SUI, SUnit *SUJ) {return false;}
void setIsLastBit(MachineInstr *MI, unsigned Bit) const {
unsigned LastOp = TII->getOperandIdx(MI->getOpcode(), R600Operands::LAST);
MI->getOperand(LastOp).setImm(Bit);
}
MachineBasicBlock::iterator addToPacket(MachineInstr *MI) {
CurrentPacketMIs.push_back(MI);
bool FitsConstLimits = TII->canBundle(CurrentPacketMIs);
DEBUG(
if (!FitsConstLimits) {
dbgs() << "Couldn't pack :\n";
MI->dump();
dbgs() << "with the following packets :\n";
for (unsigned i = 0, e = CurrentPacketMIs.size() - 1; i < e; i++) {
CurrentPacketMIs[i]->dump();
dbgs() << "\n";
}
dbgs() << "because of Consts read limitations\n";
});
const DenseMap<unsigned, unsigned> &PV =
getPreviousVector(CurrentPacketMIs.front());
std::vector<R600InstrInfo::BankSwizzle> BS;
bool FitsReadPortLimits =
TII->fitsReadPortLimitations(CurrentPacketMIs, PV, BS);
DEBUG(
if (!FitsReadPortLimits) {
dbgs() << "Couldn't pack :\n";
MI->dump();
dbgs() << "with the following packets :\n";
for (unsigned i = 0, e = CurrentPacketMIs.size() - 1; i < e; i++) {
CurrentPacketMIs[i]->dump();
dbgs() << "\n";
}
dbgs() << "because of Read port limitations\n";
});
bool isBundlable = FitsConstLimits && FitsReadPortLimits;
if (isBundlable) {
for (unsigned i = 0, e = CurrentPacketMIs.size(); i < e; i++) {
MachineInstr *MI = CurrentPacketMIs[i];
unsigned Op = TII->getOperandIdx(MI->getOpcode(),
R600Operands::BANK_SWIZZLE);
MI->getOperand(Op).setImm(BS[i]);
}
}
CurrentPacketMIs.pop_back();
if (!isBundlable) {
endPacket(MI->getParent(), MI);
substitutePV(MI, getPreviousVector(MI));
return VLIWPacketizerList::addToPacket(MI);
}
if (!CurrentPacketMIs.empty())
setIsLastBit(CurrentPacketMIs.back(), 0);
substitutePV(MI, PV);
return VLIWPacketizerList::addToPacket(MI);
}
};
bool R600Packetizer::runOnMachineFunction(MachineFunction &Fn) {
const TargetInstrInfo *TII = Fn.getTarget().getInstrInfo();
MachineLoopInfo &MLI = getAnalysis<MachineLoopInfo>();
MachineDominatorTree &MDT = getAnalysis<MachineDominatorTree>();
// Instantiate the packetizer.
R600PacketizerList Packetizer(Fn, MLI, MDT);
// DFA state table should not be empty.
assert(Packetizer.getResourceTracker() && "Empty DFA table!");
//
// Loop over all basic blocks and remove KILL pseudo-instructions
// These instructions confuse the dependence analysis. Consider:
// D0 = ... (Insn 0)
// R0 = KILL R0, D0 (Insn 1)
// R0 = ... (Insn 2)
// Here, Insn 1 will result in the dependence graph not emitting an output
// dependence between Insn 0 and Insn 2. This can lead to incorrect
// packetization
//
for (MachineFunction::iterator MBB = Fn.begin(), MBBe = Fn.end();
MBB != MBBe; ++MBB) {
MachineBasicBlock::iterator End = MBB->end();
MachineBasicBlock::iterator MI = MBB->begin();
while (MI != End) {
if (MI->isKill()) {
MachineBasicBlock::iterator DeleteMI = MI;
++MI;
MBB->erase(DeleteMI);
End = MBB->end();
continue;
}
++MI;
}
}
// Loop over all of the basic blocks.
for (MachineFunction::iterator MBB = Fn.begin(), MBBe = Fn.end();
MBB != MBBe; ++MBB) {
// Find scheduling regions and schedule / packetize each region.
unsigned RemainingCount = MBB->size();
for(MachineBasicBlock::iterator RegionEnd = MBB->end();
RegionEnd != MBB->begin();) {
// The next region starts above the previous region. Look backward in the
// instruction stream until we find the nearest boundary.
MachineBasicBlock::iterator I = RegionEnd;
for(;I != MBB->begin(); --I, --RemainingCount) {
if (TII->isSchedulingBoundary(llvm::prior(I), MBB, Fn))
break;
}
I = MBB->begin();
// Skip empty scheduling regions.
if (I == RegionEnd) {
RegionEnd = llvm::prior(RegionEnd);
--RemainingCount;
continue;
}
// Skip regions with one instruction.
if (I == llvm::prior(RegionEnd)) {
RegionEnd = llvm::prior(RegionEnd);
continue;
}
Packetizer.PacketizeMIs(MBB, I, RegionEnd);
RegionEnd = I;
}
}
return true;
}
} // end anonymous namespace
llvm::FunctionPass *llvm::createR600Packetizer(TargetMachine &tm) {
return new R600Packetizer(tm);
}