1 //===----- R600Packetizer.cpp - VLIW packetizer ---------------------------===//
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //===----------------------------------------------------------------------===//
10 /// This pass implements instructions packetization for R600. It unsets isLast
11 /// bit of instructions inside a bundle and substitutes src register with
12 /// PreviousVector when applicable.
14 //===----------------------------------------------------------------------===//
17 #include "AMDGPUSubtarget.h"
18 #include "R600InstrInfo.h"
19 #include "MCTargetDesc/AMDGPUMCTargetDesc.h"
20 #include "llvm/CodeGen/DFAPacketizer.h"
21 #include "llvm/CodeGen/MachineDominators.h"
22 #include "llvm/CodeGen/MachineFunctionPass.h"
23 #include "llvm/CodeGen/MachineLoopInfo.h"
24 #include "llvm/CodeGen/Passes.h"
25 #include "llvm/CodeGen/ScheduleDAG.h"
26 #include "llvm/Support/Debug.h"
27 #include "llvm/Support/raw_ostream.h"
31 #define DEBUG_TYPE "packets"
35 class R600Packetizer : public MachineFunctionPass {
39 R600Packetizer() : MachineFunctionPass(ID) {}
41 void getAnalysisUsage(AnalysisUsage &AU) const override {
43 AU.addRequired<MachineDominatorTree>();
44 AU.addPreserved<MachineDominatorTree>();
45 AU.addRequired<MachineLoopInfo>();
46 AU.addPreserved<MachineLoopInfo>();
47 MachineFunctionPass::getAnalysisUsage(AU);
50 StringRef getPassName() const override { return "R600 Packetizer"; }
52 bool runOnMachineFunction(MachineFunction &Fn) override;
55 class R600PacketizerList : public VLIWPacketizerList {
57 const R600InstrInfo *TII;
58 const R600RegisterInfo &TRI;
60 bool ConsideredInstUsesAlreadyWrittenVectorElement;
62 unsigned getSlot(const MachineInstr &MI) const {
63 return TRI.getHWRegChan(MI.getOperand(0).getReg());
66 /// \returns register to PV chan mapping for bundle/single instructions that
67 /// immediately precedes I.
68 DenseMap<unsigned, unsigned> getPreviousVector(MachineBasicBlock::iterator I)
70 DenseMap<unsigned, unsigned> Result;
72 if (!TII->isALUInstr(I->getOpcode()) && !I->isBundle())
74 MachineBasicBlock::instr_iterator BI = I.getInstrIterator();
80 int BISlot = getSlot(*BI);
81 if (LastDstChan >= BISlot)
84 if (TII->isPredicated(*BI))
86 int OperandIdx = TII->getOperandIdx(BI->getOpcode(), R600::OpName::write);
87 if (OperandIdx > -1 && BI->getOperand(OperandIdx).getImm() == 0)
89 int DstIdx = TII->getOperandIdx(BI->getOpcode(), R600::OpName::dst);
93 unsigned Dst = BI->getOperand(DstIdx).getReg();
94 if (isTrans || TII->isTransOnly(*BI)) {
95 Result[Dst] = R600::PS;
98 if (BI->getOpcode() == R600::DOT4_r600 ||
99 BI->getOpcode() == R600::DOT4_eg) {
100 Result[Dst] = R600::PV_X;
103 if (Dst == R600::OQAP) {
107 switch (TRI.getHWRegChan(Dst)) {
121 llvm_unreachable("Invalid Chan");
124 } while ((++BI)->isBundledWithPred());
128 void substitutePV(MachineInstr &MI, const DenseMap<unsigned, unsigned> &PVs)
135 for (unsigned i = 0; i < 3; i++) {
136 int OperandIdx = TII->getOperandIdx(MI.getOpcode(), Ops[i]);
139 unsigned Src = MI.getOperand(OperandIdx).getReg();
140 const DenseMap<unsigned, unsigned>::const_iterator It = PVs.find(Src);
142 MI.getOperand(OperandIdx).setReg(It->second);
147 R600PacketizerList(MachineFunction &MF, const R600Subtarget &ST,
148 MachineLoopInfo &MLI)
149 : VLIWPacketizerList(MF, MLI, nullptr),
150 TII(ST.getInstrInfo()),
151 TRI(TII->getRegisterInfo()) {
152 VLIW5 = !ST.hasCaymanISA();
155 // initPacketizerState - initialize some internal flags.
156 void initPacketizerState() override {
157 ConsideredInstUsesAlreadyWrittenVectorElement = false;
160 // ignorePseudoInstruction - Ignore bundling of pseudo instructions.
161 bool ignorePseudoInstruction(const MachineInstr &MI,
162 const MachineBasicBlock *MBB) override {
166 // isSoloInstruction - return true if instruction MI can not be packetized
167 // with any other instruction, which means that MI itself is a packet.
168 bool isSoloInstruction(const MachineInstr &MI) override {
169 if (TII->isVector(MI))
171 if (!TII->isALUInstr(MI.getOpcode()))
173 if (MI.getOpcode() == R600::GROUP_BARRIER)
175 // XXX: This can be removed once the packetizer properly handles all the
176 // LDS instruction group restrictions.
177 return TII->isLDSInstr(MI.getOpcode());
180 // isLegalToPacketizeTogether - Is it legal to packetize SUI and SUJ
182 bool isLegalToPacketizeTogether(SUnit *SUI, SUnit *SUJ) override {
183 MachineInstr *MII = SUI->getInstr(), *MIJ = SUJ->getInstr();
184 if (getSlot(*MII) == getSlot(*MIJ))
185 ConsideredInstUsesAlreadyWrittenVectorElement = true;
186 // Does MII and MIJ share the same pred_sel ?
187 int OpI = TII->getOperandIdx(MII->getOpcode(), R600::OpName::pred_sel),
188 OpJ = TII->getOperandIdx(MIJ->getOpcode(), R600::OpName::pred_sel);
189 Register PredI = (OpI > -1)?MII->getOperand(OpI).getReg() : Register(),
190 PredJ = (OpJ > -1)?MIJ->getOperand(OpJ).getReg() : Register();
193 if (SUJ->isSucc(SUI)) {
194 for (unsigned i = 0, e = SUJ->Succs.size(); i < e; ++i) {
195 const SDep &Dep = SUJ->Succs[i];
196 if (Dep.getSUnit() != SUI)
198 if (Dep.getKind() == SDep::Anti)
200 if (Dep.getKind() == SDep::Output)
201 if (MII->getOperand(0).getReg() != MIJ->getOperand(0).getReg())
208 TII->definesAddressRegister(*MII) || TII->definesAddressRegister(*MIJ);
210 TII->usesAddressRegister(*MII) || TII->usesAddressRegister(*MIJ);
212 return !ARDef || !ARUse;
215 // isLegalToPruneDependencies - Is it legal to prune dependece between SUI
217 bool isLegalToPruneDependencies(SUnit *SUI, SUnit *SUJ) override {
221 void setIsLastBit(MachineInstr *MI, unsigned Bit) const {
222 unsigned LastOp = TII->getOperandIdx(MI->getOpcode(), R600::OpName::last);
223 MI->getOperand(LastOp).setImm(Bit);
226 bool isBundlableWithCurrentPMI(MachineInstr &MI,
227 const DenseMap<unsigned, unsigned> &PV,
228 std::vector<R600InstrInfo::BankSwizzle> &BS,
230 isTransSlot = TII->isTransOnly(MI);
231 assert (!isTransSlot || VLIW5);
233 // Is the dst reg sequence legal ?
234 if (!isTransSlot && !CurrentPacketMIs.empty()) {
235 if (getSlot(MI) <= getSlot(*CurrentPacketMIs.back())) {
236 if (ConsideredInstUsesAlreadyWrittenVectorElement &&
237 !TII->isVectorOnly(MI) && VLIW5) {
240 dbgs() << "Considering as Trans Inst :";
249 // Are the Constants limitations met ?
250 CurrentPacketMIs.push_back(&MI);
251 if (!TII->fitsConstReadLimitations(CurrentPacketMIs)) {
253 dbgs() << "Couldn't pack :\n";
255 dbgs() << "with the following packets :\n";
256 for (unsigned i = 0, e = CurrentPacketMIs.size() - 1; i < e; i++) {
257 CurrentPacketMIs[i]->dump();
260 dbgs() << "because of Consts read limitations\n";
262 CurrentPacketMIs.pop_back();
266 // Is there a BankSwizzle set that meet Read Port limitations ?
267 if (!TII->fitsReadPortLimitations(CurrentPacketMIs,
268 PV, BS, isTransSlot)) {
270 dbgs() << "Couldn't pack :\n";
272 dbgs() << "with the following packets :\n";
273 for (unsigned i = 0, e = CurrentPacketMIs.size() - 1; i < e; i++) {
274 CurrentPacketMIs[i]->dump();
277 dbgs() << "because of Read port limitations\n";
279 CurrentPacketMIs.pop_back();
283 // We cannot read LDS source registers from the Trans slot.
284 if (isTransSlot && TII->readsLDSSrcReg(MI))
287 CurrentPacketMIs.pop_back();
291 MachineBasicBlock::iterator addToPacket(MachineInstr &MI) override {
292 MachineBasicBlock::iterator FirstInBundle =
293 CurrentPacketMIs.empty() ? &MI : CurrentPacketMIs.front();
294 const DenseMap<unsigned, unsigned> &PV =
295 getPreviousVector(FirstInBundle);
296 std::vector<R600InstrInfo::BankSwizzle> BS;
299 if (isBundlableWithCurrentPMI(MI, PV, BS, isTransSlot)) {
300 for (unsigned i = 0, e = CurrentPacketMIs.size(); i < e; i++) {
301 MachineInstr *MI = CurrentPacketMIs[i];
302 unsigned Op = TII->getOperandIdx(MI->getOpcode(),
303 R600::OpName::bank_swizzle);
304 MI->getOperand(Op).setImm(BS[i]);
307 TII->getOperandIdx(MI.getOpcode(), R600::OpName::bank_swizzle);
308 MI.getOperand(Op).setImm(BS.back());
309 if (!CurrentPacketMIs.empty())
310 setIsLastBit(CurrentPacketMIs.back(), 0);
311 substitutePV(MI, PV);
312 MachineBasicBlock::iterator It = VLIWPacketizerList::addToPacket(MI);
314 endPacket(std::next(It)->getParent(), std::next(It));
318 endPacket(MI.getParent(), MI);
319 if (TII->isTransOnly(MI))
321 return VLIWPacketizerList::addToPacket(MI);
325 bool R600Packetizer::runOnMachineFunction(MachineFunction &Fn) {
326 const R600Subtarget &ST = Fn.getSubtarget<R600Subtarget>();
327 const R600InstrInfo *TII = ST.getInstrInfo();
329 MachineLoopInfo &MLI = getAnalysis<MachineLoopInfo>();
331 // Instantiate the packetizer.
332 R600PacketizerList Packetizer(Fn, ST, MLI);
334 // DFA state table should not be empty.
335 assert(Packetizer.getResourceTracker() && "Empty DFA table!");
336 assert(Packetizer.getResourceTracker()->getInstrItins());
338 if (Packetizer.getResourceTracker()->getInstrItins()->isEmpty())
342 // Loop over all basic blocks and remove KILL pseudo-instructions
343 // These instructions confuse the dependence analysis. Consider:
345 // R0 = KILL R0, D0 (Insn 1)
347 // Here, Insn 1 will result in the dependence graph not emitting an output
348 // dependence between Insn 0 and Insn 2. This can lead to incorrect
351 for (MachineFunction::iterator MBB = Fn.begin(), MBBe = Fn.end();
352 MBB != MBBe; ++MBB) {
353 MachineBasicBlock::iterator End = MBB->end();
354 MachineBasicBlock::iterator MI = MBB->begin();
356 if (MI->isKill() || MI->getOpcode() == R600::IMPLICIT_DEF ||
357 (MI->getOpcode() == R600::CF_ALU && !MI->getOperand(8).getImm())) {
358 MachineBasicBlock::iterator DeleteMI = MI;
360 MBB->erase(DeleteMI);
368 // Loop over all of the basic blocks.
369 for (MachineFunction::iterator MBB = Fn.begin(), MBBe = Fn.end();
370 MBB != MBBe; ++MBB) {
371 // Find scheduling regions and schedule / packetize each region.
372 unsigned RemainingCount = MBB->size();
373 for(MachineBasicBlock::iterator RegionEnd = MBB->end();
374 RegionEnd != MBB->begin();) {
375 // The next region starts above the previous region. Look backward in the
376 // instruction stream until we find the nearest boundary.
377 MachineBasicBlock::iterator I = RegionEnd;
378 for(;I != MBB->begin(); --I, --RemainingCount) {
379 if (TII->isSchedulingBoundary(*std::prev(I), &*MBB, Fn))
384 // Skip empty scheduling regions.
385 if (I == RegionEnd) {
386 RegionEnd = std::prev(RegionEnd);
390 // Skip regions with one instruction.
391 if (I == std::prev(RegionEnd)) {
392 RegionEnd = std::prev(RegionEnd);
396 Packetizer.PacketizeMIs(&*MBB, &*I, RegionEnd);
405 } // end anonymous namespace
407 INITIALIZE_PASS_BEGIN(R600Packetizer, DEBUG_TYPE,
408 "R600 Packetizer", false, false)
409 INITIALIZE_PASS_END(R600Packetizer, DEBUG_TYPE,
410 "R600 Packetizer", false, false)
412 char R600Packetizer::ID = 0;
414 char &llvm::R600PacketizerID = R600Packetizer::ID;
416 llvm::FunctionPass *llvm::createR600Packetizer() {
417 return new R600Packetizer();