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llvm-project/llvm/lib/Target/AMDGPU/R600Packetizer.cpp

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//===----- 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.
//
//===----------------------------------------------------------------------===//
#include "AMDGPU.h"
#include "AMDGPUSubtarget.h"
#include "R600InstrInfo.h"
#include "MCTargetDesc/AMDGPUMCTargetDesc.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/Debug.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
#define DEBUG_TYPE "packets"
namespace {
class R600Packetizer : public MachineFunctionPass {
public:
static char ID;
R600Packetizer() : MachineFunctionPass(ID) {}
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.setPreservesCFG();
AU.addRequired<MachineDominatorTree>();
AU.addPreserved<MachineDominatorTree>();
AU.addRequired<MachineLoopInfo>();
AU.addPreserved<MachineLoopInfo>();
MachineFunctionPass::getAnalysisUsage(AU);
}
StringRef getPassName() const override { return "R600 Packetizer"; }
bool runOnMachineFunction(MachineFunction &Fn) override;
};
class R600PacketizerList : public VLIWPacketizerList {
private:
const R600InstrInfo *TII;
const R600RegisterInfo &TRI;
bool VLIW5;
bool ConsideredInstUsesAlreadyWrittenVectorElement;
unsigned getSlot(const MachineInstr &MI) const {
return TRI.getHWRegChan(MI.getOperand(0).getReg());
}
/// \returns register to PV chan mapping for bundle/single instructions that
/// immediately 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++;
int LastDstChan = -1;
do {
bool isTrans = false;
int BISlot = getSlot(*BI);
if (LastDstChan >= BISlot)
isTrans = true;
LastDstChan = BISlot;
if (TII->isPredicated(*BI))
continue;
int OperandIdx = TII->getOperandIdx(BI->getOpcode(), R600::OpName::write);
if (OperandIdx > -1 && BI->getOperand(OperandIdx).getImm() == 0)
continue;
int DstIdx = TII->getOperandIdx(BI->getOpcode(), R600::OpName::dst);
if (DstIdx == -1) {
continue;
}
unsigned Dst = BI->getOperand(DstIdx).getReg();
if (isTrans || TII->isTransOnly(*BI)) {
Result[Dst] = R600::PS;
continue;
}
if (BI->getOpcode() == R600::DOT4_r600 ||
BI->getOpcode() == R600::DOT4_eg) {
Result[Dst] = R600::PV_X;
continue;
}
if (Dst == R600::OQAP) {
continue;
}
unsigned PVReg = 0;
switch (TRI.getHWRegChan(Dst)) {
case 0:
PVReg = R600::PV_X;
break;
case 1:
PVReg = R600::PV_Y;
break;
case 2:
PVReg = R600::PV_Z;
break;
case 3:
PVReg = R600::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 {
unsigned Ops[] = {
R600::OpName::src0,
R600::OpName::src1,
R600::OpName::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, const R600Subtarget &ST,
MachineLoopInfo &MLI)
: VLIWPacketizerList(MF, MLI, nullptr),
TII(ST.getInstrInfo()),
TRI(TII->getRegisterInfo()) {
VLIW5 = !ST.hasCaymanISA();
}
// initPacketizerState - initialize some internal flags.
void initPacketizerState() override {
ConsideredInstUsesAlreadyWrittenVectorElement = false;
}
// ignorePseudoInstruction - Ignore bundling of pseudo instructions.
bool ignorePseudoInstruction(const MachineInstr &MI,
const MachineBasicBlock *MBB) override {
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(const MachineInstr &MI) override {
if (TII->isVector(MI))
return true;
if (!TII->isALUInstr(MI.getOpcode()))
return true;
if (MI.getOpcode() == R600::GROUP_BARRIER)
return true;
// XXX: This can be removed once the packetizer properly handles all the
// LDS instruction group restrictions.
return TII->isLDSInstr(MI.getOpcode());
}
// isLegalToPacketizeTogether - Is it legal to packetize SUI and SUJ
// together.
bool isLegalToPacketizeTogether(SUnit *SUI, SUnit *SUJ) override {
MachineInstr *MII = SUI->getInstr(), *MIJ = SUJ->getInstr();
if (getSlot(*MII) == getSlot(*MIJ))
ConsideredInstUsesAlreadyWrittenVectorElement = true;
// Does MII and MIJ share the same pred_sel ?
int OpI = TII->getOperandIdx(MII->getOpcode(), R600::OpName::pred_sel),
OpJ = TII->getOperandIdx(MIJ->getOpcode(), R600::OpName::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;
}
}
bool ARDef =
TII->definesAddressRegister(*MII) || TII->definesAddressRegister(*MIJ);
bool ARUse =
TII->usesAddressRegister(*MII) || TII->usesAddressRegister(*MIJ);
return !ARDef || !ARUse;
}
// isLegalToPruneDependencies - Is it legal to prune dependece between SUI
// and SUJ.
bool isLegalToPruneDependencies(SUnit *SUI, SUnit *SUJ) override {
return false;
}
void setIsLastBit(MachineInstr *MI, unsigned Bit) const {
unsigned LastOp = TII->getOperandIdx(MI->getOpcode(), R600::OpName::last);
MI->getOperand(LastOp).setImm(Bit);
}
bool isBundlableWithCurrentPMI(MachineInstr &MI,
const DenseMap<unsigned, unsigned> &PV,
std::vector<R600InstrInfo::BankSwizzle> &BS,
bool &isTransSlot) {
isTransSlot = TII->isTransOnly(MI);
assert (!isTransSlot || VLIW5);
// Is the dst reg sequence legal ?
if (!isTransSlot && !CurrentPacketMIs.empty()) {
if (getSlot(MI) <= getSlot(*CurrentPacketMIs.back())) {
if (ConsideredInstUsesAlreadyWrittenVectorElement &&
!TII->isVectorOnly(MI) && VLIW5) {
isTransSlot = true;
LLVM_DEBUG({
dbgs() << "Considering as Trans Inst :";
MI.dump();
});
}
else
return false;
}
}
// Are the Constants limitations met ?
CurrentPacketMIs.push_back(&MI);
if (!TII->fitsConstReadLimitations(CurrentPacketMIs)) {
LLVM_DEBUG({
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";
});
CurrentPacketMIs.pop_back();
return false;
}
// Is there a BankSwizzle set that meet Read Port limitations ?
if (!TII->fitsReadPortLimitations(CurrentPacketMIs,
PV, BS, isTransSlot)) {
LLVM_DEBUG({
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";
});
CurrentPacketMIs.pop_back();
return false;
}
// We cannot read LDS source registers from the Trans slot.
if (isTransSlot && TII->readsLDSSrcReg(MI))
return false;
CurrentPacketMIs.pop_back();
return true;
}
MachineBasicBlock::iterator addToPacket(MachineInstr &MI) override {
MachineBasicBlock::iterator FirstInBundle =
CurrentPacketMIs.empty() ? &MI : CurrentPacketMIs.front();
const DenseMap<unsigned, unsigned> &PV =
getPreviousVector(FirstInBundle);
std::vector<R600InstrInfo::BankSwizzle> BS;
bool isTransSlot;
if (isBundlableWithCurrentPMI(MI, PV, BS, isTransSlot)) {
for (unsigned i = 0, e = CurrentPacketMIs.size(); i < e; i++) {
MachineInstr *MI = CurrentPacketMIs[i];
unsigned Op = TII->getOperandIdx(MI->getOpcode(),
R600::OpName::bank_swizzle);
MI->getOperand(Op).setImm(BS[i]);
}
unsigned Op =
TII->getOperandIdx(MI.getOpcode(), R600::OpName::bank_swizzle);
MI.getOperand(Op).setImm(BS.back());
if (!CurrentPacketMIs.empty())
setIsLastBit(CurrentPacketMIs.back(), 0);
substitutePV(MI, PV);
MachineBasicBlock::iterator It = VLIWPacketizerList::addToPacket(MI);
if (isTransSlot) {
endPacket(std::next(It)->getParent(), std::next(It));
}
return It;
}
endPacket(MI.getParent(), MI);
if (TII->isTransOnly(MI))
return MI;
return VLIWPacketizerList::addToPacket(MI);
}
};
bool R600Packetizer::runOnMachineFunction(MachineFunction &Fn) {
const R600Subtarget &ST = Fn.getSubtarget<R600Subtarget>();
const R600InstrInfo *TII = ST.getInstrInfo();
MachineLoopInfo &MLI = getAnalysis<MachineLoopInfo>();
// Instantiate the packetizer.
R600PacketizerList Packetizer(Fn, ST, MLI);
// DFA state table should not be empty.
assert(Packetizer.getResourceTracker() && "Empty DFA table!");
assert(Packetizer.getResourceTracker()->getInstrItins());
if (Packetizer.getResourceTracker()->getInstrItins()->isEmpty())
return false;
//
// 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() || MI->getOpcode() == R600::IMPLICIT_DEF ||
(MI->getOpcode() == R600::CF_ALU && !MI->getOperand(8).getImm())) {
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(*std::prev(I), &*MBB, Fn))
break;
}
I = MBB->begin();
// Skip empty scheduling regions.
if (I == RegionEnd) {
RegionEnd = std::prev(RegionEnd);
--RemainingCount;
continue;
}
// Skip regions with one instruction.
if (I == std::prev(RegionEnd)) {
RegionEnd = std::prev(RegionEnd);
continue;
}
Packetizer.PacketizeMIs(&*MBB, &*I, RegionEnd);
RegionEnd = I;
}
}
return true;
}
} // end anonymous namespace
INITIALIZE_PASS_BEGIN(R600Packetizer, DEBUG_TYPE,
"R600 Packetizer", false, false)
INITIALIZE_PASS_END(R600Packetizer, DEBUG_TYPE,
"R600 Packetizer", false, false)
char R600Packetizer::ID = 0;
char &llvm::R600PacketizerID = R600Packetizer::ID;
llvm::FunctionPass *llvm::createR600Packetizer() {
return new R600Packetizer();
}
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