1 //===-- R600ControlFlowFinalizer.cpp - Finalize Control Flow Inst----------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
11 /// This pass compute turns all control flow pseudo instructions into native one
12 /// computing their address on the fly ; it also sets STACK_SIZE info.
13 //===----------------------------------------------------------------------===//
15 #include "llvm/Support/Debug.h"
17 #include "AMDGPUSubtarget.h"
18 #include "R600Defines.h"
19 #include "R600InstrInfo.h"
20 #include "R600MachineFunctionInfo.h"
21 #include "R600RegisterInfo.h"
22 #include "llvm/CodeGen/MachineFunctionPass.h"
23 #include "llvm/CodeGen/MachineInstrBuilder.h"
24 #include "llvm/CodeGen/MachineRegisterInfo.h"
25 #include "llvm/Support/raw_ostream.h"
29 #define DEBUG_TYPE "r600cf"
38 FIRST_NON_WQM_PUSH = 2,
39 FIRST_NON_WQM_PUSH_W_FULL_ENTRY = 3
42 const R600Subtarget *ST;
43 std::vector<StackItem> BranchStack;
44 std::vector<StackItem> LoopStack;
45 unsigned MaxStackSize;
46 unsigned CurrentEntries;
47 unsigned CurrentSubEntries;
49 CFStack(const R600Subtarget *st, CallingConv::ID cc) : ST(st),
50 // We need to reserve a stack entry for CALL_FS in vertex shaders.
51 MaxStackSize(cc == CallingConv::AMDGPU_VS ? 1 : 0),
52 CurrentEntries(0), CurrentSubEntries(0) { }
54 unsigned getLoopDepth();
55 bool branchStackContains(CFStack::StackItem);
56 bool requiresWorkAroundForInst(unsigned Opcode);
57 unsigned getSubEntrySize(CFStack::StackItem Item);
58 void updateMaxStackSize();
59 void pushBranch(unsigned Opcode, bool isWQM = false);
65 unsigned CFStack::getLoopDepth() {
66 return LoopStack.size();
69 bool CFStack::branchStackContains(CFStack::StackItem Item) {
70 for (std::vector<CFStack::StackItem>::const_iterator I = BranchStack.begin(),
71 E = BranchStack.end(); I != E; ++I) {
78 bool CFStack::requiresWorkAroundForInst(unsigned Opcode) {
79 if (Opcode == AMDGPU::CF_ALU_PUSH_BEFORE && ST->hasCaymanISA() &&
83 if (!ST->hasCFAluBug())
87 default: return false;
88 case AMDGPU::CF_ALU_PUSH_BEFORE:
89 case AMDGPU::CF_ALU_ELSE_AFTER:
90 case AMDGPU::CF_ALU_BREAK:
91 case AMDGPU::CF_ALU_CONTINUE:
92 if (CurrentSubEntries == 0)
94 if (ST->getWavefrontSize() == 64) {
95 // We are being conservative here. We only require this work-around if
96 // CurrentSubEntries > 3 &&
97 // (CurrentSubEntries % 4 == 3 || CurrentSubEntries % 4 == 0)
99 // We have to be conservative, because we don't know for certain that
100 // our stack allocation algorithm for Evergreen/NI is correct. Applying this
101 // work-around when CurrentSubEntries > 3 allows us to over-allocate stack
102 // resources without any problems.
103 return CurrentSubEntries > 3;
105 assert(ST->getWavefrontSize() == 32);
106 // We are being conservative here. We only require the work-around if
107 // CurrentSubEntries > 7 &&
108 // (CurrentSubEntries % 8 == 7 || CurrentSubEntries % 8 == 0)
109 // See the comment on the wavefront size == 64 case for why we are
110 // being conservative.
111 return CurrentSubEntries > 7;
116 unsigned CFStack::getSubEntrySize(CFStack::StackItem Item) {
120 case CFStack::FIRST_NON_WQM_PUSH:
121 assert(!ST->hasCaymanISA());
122 if (ST->getGeneration() <= R600Subtarget::R700) {
123 // +1 For the push operation.
124 // +2 Extra space required.
127 // Some documentation says that this is not necessary on Evergreen,
128 // but experimentation has show that we need to allocate 1 extra
129 // sub-entry for the first non-WQM push.
130 // +1 For the push operation.
131 // +1 Extra space required.
134 case CFStack::FIRST_NON_WQM_PUSH_W_FULL_ENTRY:
135 assert(ST->getGeneration() >= R600Subtarget::EVERGREEN);
136 // +1 For the push operation.
137 // +1 Extra space required.
139 case CFStack::SUB_ENTRY:
144 void CFStack::updateMaxStackSize() {
145 unsigned CurrentStackSize =
146 CurrentEntries + (alignTo(CurrentSubEntries, 4) / 4);
147 MaxStackSize = std::max(CurrentStackSize, MaxStackSize);
150 void CFStack::pushBranch(unsigned Opcode, bool isWQM) {
151 CFStack::StackItem Item = CFStack::ENTRY;
153 case AMDGPU::CF_PUSH_EG:
154 case AMDGPU::CF_ALU_PUSH_BEFORE:
156 if (!ST->hasCaymanISA() &&
157 !branchStackContains(CFStack::FIRST_NON_WQM_PUSH))
158 Item = CFStack::FIRST_NON_WQM_PUSH; // May not be required on Evergreen/NI
160 // CFStack::getSubEntrySize()
161 else if (CurrentEntries > 0 &&
162 ST->getGeneration() > R600Subtarget::EVERGREEN &&
163 !ST->hasCaymanISA() &&
164 !branchStackContains(CFStack::FIRST_NON_WQM_PUSH_W_FULL_ENTRY))
165 Item = CFStack::FIRST_NON_WQM_PUSH_W_FULL_ENTRY;
167 Item = CFStack::SUB_ENTRY;
169 Item = CFStack::ENTRY;
172 BranchStack.push_back(Item);
173 if (Item == CFStack::ENTRY)
176 CurrentSubEntries += getSubEntrySize(Item);
177 updateMaxStackSize();
180 void CFStack::pushLoop() {
181 LoopStack.push_back(CFStack::ENTRY);
183 updateMaxStackSize();
186 void CFStack::popBranch() {
187 CFStack::StackItem Top = BranchStack.back();
188 if (Top == CFStack::ENTRY)
191 CurrentSubEntries-= getSubEntrySize(Top);
192 BranchStack.pop_back();
195 void CFStack::popLoop() {
197 LoopStack.pop_back();
200 class R600ControlFlowFinalizer : public MachineFunctionPass {
203 typedef std::pair<MachineInstr *, std::vector<MachineInstr *> > ClauseFile;
205 enum ControlFlowInstruction {
220 const R600InstrInfo *TII;
221 const R600RegisterInfo *TRI;
222 unsigned MaxFetchInst;
223 const R600Subtarget *ST;
225 bool IsTrivialInst(MachineInstr *MI) const {
226 switch (MI->getOpcode()) {
235 const MCInstrDesc &getHWInstrDesc(ControlFlowInstruction CFI) const {
237 bool isEg = (ST->getGeneration() >= R600Subtarget::EVERGREEN);
240 Opcode = isEg ? AMDGPU::CF_TC_EG : AMDGPU::CF_TC_R600;
243 Opcode = isEg ? AMDGPU::CF_VC_EG : AMDGPU::CF_VC_R600;
246 Opcode = isEg ? AMDGPU::CF_CALL_FS_EG : AMDGPU::CF_CALL_FS_R600;
249 Opcode = isEg ? AMDGPU::WHILE_LOOP_EG : AMDGPU::WHILE_LOOP_R600;
252 Opcode = isEg ? AMDGPU::END_LOOP_EG : AMDGPU::END_LOOP_R600;
255 Opcode = isEg ? AMDGPU::LOOP_BREAK_EG : AMDGPU::LOOP_BREAK_R600;
257 case CF_LOOP_CONTINUE:
258 Opcode = isEg ? AMDGPU::CF_CONTINUE_EG : AMDGPU::CF_CONTINUE_R600;
261 Opcode = isEg ? AMDGPU::CF_JUMP_EG : AMDGPU::CF_JUMP_R600;
264 Opcode = isEg ? AMDGPU::CF_ELSE_EG : AMDGPU::CF_ELSE_R600;
267 Opcode = isEg ? AMDGPU::POP_EG : AMDGPU::POP_R600;
270 if (ST->hasCaymanISA()) {
271 Opcode = AMDGPU::CF_END_CM;
274 Opcode = isEg ? AMDGPU::CF_END_EG : AMDGPU::CF_END_R600;
277 assert (Opcode && "No opcode selected");
278 return TII->get(Opcode);
281 bool isCompatibleWithClause(const MachineInstr *MI,
282 std::set<unsigned> &DstRegs) const {
283 unsigned DstMI, SrcMI;
284 for (MachineInstr::const_mop_iterator I = MI->operands_begin(),
285 E = MI->operands_end(); I != E; ++I) {
286 const MachineOperand &MO = *I;
290 unsigned Reg = MO.getReg();
291 if (AMDGPU::R600_Reg128RegClass.contains(Reg))
294 DstMI = TRI->getMatchingSuperReg(Reg,
295 TRI->getSubRegFromChannel(TRI->getHWRegChan(Reg)),
296 &AMDGPU::R600_Reg128RegClass);
299 unsigned Reg = MO.getReg();
300 if (AMDGPU::R600_Reg128RegClass.contains(Reg))
303 SrcMI = TRI->getMatchingSuperReg(Reg,
304 TRI->getSubRegFromChannel(TRI->getHWRegChan(Reg)),
305 &AMDGPU::R600_Reg128RegClass);
308 if ((DstRegs.find(SrcMI) == DstRegs.end())) {
309 DstRegs.insert(DstMI);
316 MakeFetchClause(MachineBasicBlock &MBB, MachineBasicBlock::iterator &I)
318 MachineBasicBlock::iterator ClauseHead = I;
319 std::vector<MachineInstr *> ClauseContent;
320 unsigned AluInstCount = 0;
321 bool IsTex = TII->usesTextureCache(*ClauseHead);
322 std::set<unsigned> DstRegs;
323 for (MachineBasicBlock::iterator E = MBB.end(); I != E; ++I) {
324 if (IsTrivialInst(I))
326 if (AluInstCount >= MaxFetchInst)
328 if ((IsTex && !TII->usesTextureCache(*I)) ||
329 (!IsTex && !TII->usesVertexCache(*I)))
331 if (!isCompatibleWithClause(I, DstRegs))
334 ClauseContent.push_back(I);
336 MachineInstr *MIb = BuildMI(MBB, ClauseHead, MBB.findDebugLoc(ClauseHead),
337 getHWInstrDesc(IsTex?CF_TC:CF_VC))
339 .addImm(AluInstCount - 1); // COUNT
340 return ClauseFile(MIb, std::move(ClauseContent));
343 void getLiteral(MachineInstr *MI, std::vector<MachineOperand *> &Lits) const {
344 static const unsigned LiteralRegs[] = {
345 AMDGPU::ALU_LITERAL_X,
346 AMDGPU::ALU_LITERAL_Y,
347 AMDGPU::ALU_LITERAL_Z,
348 AMDGPU::ALU_LITERAL_W
350 const SmallVector<std::pair<MachineOperand *, int64_t>, 3> Srcs =
352 for (const auto &Src:Srcs) {
353 if (Src.first->getReg() != AMDGPU::ALU_LITERAL_X)
355 int64_t Imm = Src.second;
356 std::vector<MachineOperand*>::iterator It =
357 std::find_if(Lits.begin(), Lits.end(),
358 [&](MachineOperand* val)
359 { return val->isImm() && (val->getImm() == Imm);});
361 // Get corresponding Operand
362 MachineOperand &Operand = MI->getOperand(
363 TII->getOperandIdx(MI->getOpcode(), AMDGPU::OpName::literal));
365 if (It != Lits.end()) {
366 // Reuse existing literal reg
367 unsigned Index = It - Lits.begin();
368 Src.first->setReg(LiteralRegs[Index]);
370 // Allocate new literal reg
371 assert(Lits.size() < 4 && "Too many literals in Instruction Group");
372 Src.first->setReg(LiteralRegs[Lits.size()]);
373 Lits.push_back(&Operand);
378 MachineBasicBlock::iterator insertLiterals(
379 MachineBasicBlock::iterator InsertPos,
380 const std::vector<unsigned> &Literals) const {
381 MachineBasicBlock *MBB = InsertPos->getParent();
382 for (unsigned i = 0, e = Literals.size(); i < e; i+=2) {
383 unsigned LiteralPair0 = Literals[i];
384 unsigned LiteralPair1 = (i + 1 < e)?Literals[i + 1]:0;
385 InsertPos = BuildMI(MBB, InsertPos->getDebugLoc(),
386 TII->get(AMDGPU::LITERALS))
387 .addImm(LiteralPair0)
388 .addImm(LiteralPair1);
394 MakeALUClause(MachineBasicBlock &MBB, MachineBasicBlock::iterator &I)
396 MachineBasicBlock::iterator ClauseHead = I;
397 std::vector<MachineInstr *> ClauseContent;
399 for (MachineBasicBlock::instr_iterator E = MBB.instr_end(); I != E;) {
400 if (IsTrivialInst(I)) {
404 if (!I->isBundle() && !TII->isALUInstr(I->getOpcode()))
406 std::vector<MachineOperand *>Literals;
408 MachineInstr *DeleteMI = I;
409 MachineBasicBlock::instr_iterator BI = I.getInstrIterator();
410 while (++BI != E && BI->isBundledWithPred()) {
411 BI->unbundleFromPred();
412 for (MachineOperand &MO : BI->operands()) {
413 if (MO.isReg() && MO.isInternalRead())
414 MO.setIsInternalRead(false);
416 getLiteral(&*BI, Literals);
417 ClauseContent.push_back(&*BI);
420 DeleteMI->eraseFromParent();
422 getLiteral(I, Literals);
423 ClauseContent.push_back(I);
426 for (unsigned i = 0, e = Literals.size(); i < e; i += 2) {
427 MachineInstrBuilder MILit = BuildMI(MBB, I, I->getDebugLoc(),
428 TII->get(AMDGPU::LITERALS));
429 if (Literals[i]->isImm()) {
430 MILit.addImm(Literals[i]->getImm());
432 MILit.addGlobalAddress(Literals[i]->getGlobal(),
433 Literals[i]->getOffset());
436 if (Literals[i + 1]->isImm()) {
437 MILit.addImm(Literals[i + 1]->getImm());
439 MILit.addGlobalAddress(Literals[i + 1]->getGlobal(),
440 Literals[i + 1]->getOffset());
444 ClauseContent.push_back(MILit);
447 assert(ClauseContent.size() < 128 && "ALU clause is too big");
448 ClauseHead->getOperand(7).setImm(ClauseContent.size() - 1);
449 return ClauseFile(ClauseHead, std::move(ClauseContent));
453 EmitFetchClause(MachineBasicBlock::iterator InsertPos, ClauseFile &Clause,
455 CounterPropagateAddr(Clause.first, CfCount);
456 MachineBasicBlock *BB = Clause.first->getParent();
457 BuildMI(BB, InsertPos->getDebugLoc(), TII->get(AMDGPU::FETCH_CLAUSE))
459 for (unsigned i = 0, e = Clause.second.size(); i < e; ++i) {
460 BB->splice(InsertPos, BB, Clause.second[i]);
462 CfCount += 2 * Clause.second.size();
466 EmitALUClause(MachineBasicBlock::iterator InsertPos, ClauseFile &Clause,
468 Clause.first->getOperand(0).setImm(0);
469 CounterPropagateAddr(Clause.first, CfCount);
470 MachineBasicBlock *BB = Clause.first->getParent();
471 BuildMI(BB, InsertPos->getDebugLoc(), TII->get(AMDGPU::ALU_CLAUSE))
473 for (unsigned i = 0, e = Clause.second.size(); i < e; ++i) {
474 BB->splice(InsertPos, BB, Clause.second[i]);
476 CfCount += Clause.second.size();
479 void CounterPropagateAddr(MachineInstr *MI, unsigned Addr) const {
480 MI->getOperand(0).setImm(Addr + MI->getOperand(0).getImm());
482 void CounterPropagateAddr(const std::set<MachineInstr *> &MIs,
483 unsigned Addr) const {
484 for (MachineInstr *MI : MIs) {
485 CounterPropagateAddr(MI, Addr);
490 R600ControlFlowFinalizer(TargetMachine &tm)
491 : MachineFunctionPass(ID), TII(nullptr), TRI(nullptr), ST(nullptr) {}
493 bool runOnMachineFunction(MachineFunction &MF) override {
494 ST = &MF.getSubtarget<R600Subtarget>();
495 MaxFetchInst = ST->getTexVTXClauseSize();
496 TII = ST->getInstrInfo();
497 TRI = ST->getRegisterInfo();
499 R600MachineFunctionInfo *MFI = MF.getInfo<R600MachineFunctionInfo>();
501 CFStack CFStack(ST, MF.getFunction()->getCallingConv());
502 for (MachineFunction::iterator MB = MF.begin(), ME = MF.end(); MB != ME;
504 MachineBasicBlock &MBB = *MB;
505 unsigned CfCount = 0;
506 std::vector<std::pair<unsigned, std::set<MachineInstr *> > > LoopStack;
507 std::vector<MachineInstr * > IfThenElseStack;
508 if (MF.getFunction()->getCallingConv() == CallingConv::AMDGPU_VS) {
509 BuildMI(MBB, MBB.begin(), MBB.findDebugLoc(MBB.begin()),
510 getHWInstrDesc(CF_CALL_FS));
513 std::vector<ClauseFile> FetchClauses, AluClauses;
514 std::vector<MachineInstr *> LastAlu(1);
515 std::vector<MachineInstr *> ToPopAfter;
517 for (MachineBasicBlock::iterator I = MBB.begin(), E = MBB.end();
519 if (TII->usesTextureCache(*I) || TII->usesVertexCache(*I)) {
520 DEBUG(dbgs() << CfCount << ":"; I->dump(););
521 FetchClauses.push_back(MakeFetchClause(MBB, I));
523 LastAlu.back() = nullptr;
527 MachineBasicBlock::iterator MI = I;
528 if (MI->getOpcode() != AMDGPU::ENDIF)
529 LastAlu.back() = nullptr;
530 if (MI->getOpcode() == AMDGPU::CF_ALU)
533 bool RequiresWorkAround =
534 CFStack.requiresWorkAroundForInst(MI->getOpcode());
535 switch (MI->getOpcode()) {
536 case AMDGPU::CF_ALU_PUSH_BEFORE:
537 if (RequiresWorkAround) {
538 DEBUG(dbgs() << "Applying bug work-around for ALU_PUSH_BEFORE\n");
539 BuildMI(MBB, MI, MBB.findDebugLoc(MI), TII->get(AMDGPU::CF_PUSH_EG))
542 MI->setDesc(TII->get(AMDGPU::CF_ALU));
544 CFStack.pushBranch(AMDGPU::CF_PUSH_EG);
546 CFStack.pushBranch(AMDGPU::CF_ALU_PUSH_BEFORE);
550 AluClauses.push_back(MakeALUClause(MBB, I));
551 DEBUG(dbgs() << CfCount << ":"; MI->dump(););
554 case AMDGPU::WHILELOOP: {
556 MachineInstr *MIb = BuildMI(MBB, MI, MBB.findDebugLoc(MI),
557 getHWInstrDesc(CF_WHILE_LOOP))
559 std::pair<unsigned, std::set<MachineInstr *> > Pair(CfCount,
560 std::set<MachineInstr *>());
561 Pair.second.insert(MIb);
562 LoopStack.push_back(std::move(Pair));
563 MI->eraseFromParent();
567 case AMDGPU::ENDLOOP: {
569 std::pair<unsigned, std::set<MachineInstr *> > Pair =
570 std::move(LoopStack.back());
571 LoopStack.pop_back();
572 CounterPropagateAddr(Pair.second, CfCount);
573 BuildMI(MBB, MI, MBB.findDebugLoc(MI), getHWInstrDesc(CF_END_LOOP))
574 .addImm(Pair.first + 1);
575 MI->eraseFromParent();
579 case AMDGPU::IF_PREDICATE_SET: {
580 LastAlu.push_back(nullptr);
581 MachineInstr *MIb = BuildMI(MBB, MI, MBB.findDebugLoc(MI),
582 getHWInstrDesc(CF_JUMP))
585 IfThenElseStack.push_back(MIb);
586 DEBUG(dbgs() << CfCount << ":"; MIb->dump(););
587 MI->eraseFromParent();
592 MachineInstr * JumpInst = IfThenElseStack.back();
593 IfThenElseStack.pop_back();
594 CounterPropagateAddr(JumpInst, CfCount);
595 MachineInstr *MIb = BuildMI(MBB, MI, MBB.findDebugLoc(MI),
596 getHWInstrDesc(CF_ELSE))
599 DEBUG(dbgs() << CfCount << ":"; MIb->dump(););
600 IfThenElseStack.push_back(MIb);
601 MI->eraseFromParent();
605 case AMDGPU::ENDIF: {
607 if (LastAlu.back()) {
608 ToPopAfter.push_back(LastAlu.back());
610 MachineInstr *MIb = BuildMI(MBB, MI, MBB.findDebugLoc(MI),
611 getHWInstrDesc(CF_POP))
615 DEBUG(dbgs() << CfCount << ":"; MIb->dump(););
619 MachineInstr *IfOrElseInst = IfThenElseStack.back();
620 IfThenElseStack.pop_back();
621 CounterPropagateAddr(IfOrElseInst, CfCount);
622 IfOrElseInst->getOperand(1).setImm(1);
624 MI->eraseFromParent();
627 case AMDGPU::BREAK: {
629 MachineInstr *MIb = BuildMI(MBB, MI, MBB.findDebugLoc(MI),
630 getHWInstrDesc(CF_LOOP_BREAK))
632 LoopStack.back().second.insert(MIb);
633 MI->eraseFromParent();
636 case AMDGPU::CONTINUE: {
637 MachineInstr *MIb = BuildMI(MBB, MI, MBB.findDebugLoc(MI),
638 getHWInstrDesc(CF_LOOP_CONTINUE))
640 LoopStack.back().second.insert(MIb);
641 MI->eraseFromParent();
645 case AMDGPU::RETURN: {
646 BuildMI(MBB, MI, MBB.findDebugLoc(MI), getHWInstrDesc(CF_END));
649 BuildMI(MBB, I, MBB.findDebugLoc(MI), TII->get(AMDGPU::PAD));
652 MI->eraseFromParent();
653 for (unsigned i = 0, e = FetchClauses.size(); i < e; i++)
654 EmitFetchClause(I, FetchClauses[i], CfCount);
655 for (unsigned i = 0, e = AluClauses.size(); i < e; i++)
656 EmitALUClause(I, AluClauses[i], CfCount);
660 if (TII->isExport(MI->getOpcode())) {
661 DEBUG(dbgs() << CfCount << ":"; MI->dump(););
667 for (unsigned i = 0, e = ToPopAfter.size(); i < e; ++i) {
668 MachineInstr *Alu = ToPopAfter[i];
669 BuildMI(MBB, Alu, MBB.findDebugLoc((MachineBasicBlock::iterator)Alu),
670 TII->get(AMDGPU::CF_ALU_POP_AFTER))
671 .addImm(Alu->getOperand(0).getImm())
672 .addImm(Alu->getOperand(1).getImm())
673 .addImm(Alu->getOperand(2).getImm())
674 .addImm(Alu->getOperand(3).getImm())
675 .addImm(Alu->getOperand(4).getImm())
676 .addImm(Alu->getOperand(5).getImm())
677 .addImm(Alu->getOperand(6).getImm())
678 .addImm(Alu->getOperand(7).getImm())
679 .addImm(Alu->getOperand(8).getImm());
680 Alu->eraseFromParent();
682 MFI->StackSize = CFStack.MaxStackSize;
688 const char *getPassName() const override {
689 return "R600 Control Flow Finalizer Pass";
693 char R600ControlFlowFinalizer::ID = 0;
695 } // end anonymous namespace
698 llvm::FunctionPass *llvm::createR600ControlFlowFinalizer(TargetMachine &TM) {
699 return new R600ControlFlowFinalizer(TM);