1 //===- R600ControlFlowFinalizer.cpp - Finalize Control Flow Inst ----------===//
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 compute turns all control flow pseudo instructions into native one
11 /// computing their address on the fly; it also sets STACK_SIZE info.
13 //===----------------------------------------------------------------------===//
16 #include "AMDGPUSubtarget.h"
17 #include "R600Defines.h"
18 #include "R600InstrInfo.h"
19 #include "R600MachineFunctionInfo.h"
20 #include "R600RegisterInfo.h"
21 #include "MCTargetDesc/AMDGPUMCTargetDesc.h"
22 #include "llvm/ADT/STLExtras.h"
23 #include "llvm/ADT/SmallVector.h"
24 #include "llvm/ADT/StringRef.h"
25 #include "llvm/CodeGen/MachineBasicBlock.h"
26 #include "llvm/CodeGen/MachineFunction.h"
27 #include "llvm/CodeGen/MachineFunctionPass.h"
28 #include "llvm/CodeGen/MachineInstr.h"
29 #include "llvm/CodeGen/MachineInstrBuilder.h"
30 #include "llvm/CodeGen/MachineOperand.h"
31 #include "llvm/IR/CallingConv.h"
32 #include "llvm/IR/DebugLoc.h"
33 #include "llvm/IR/Function.h"
34 #include "llvm/Pass.h"
35 #include "llvm/Support/Compiler.h"
36 #include "llvm/Support/Debug.h"
37 #include "llvm/Support/MathExtras.h"
38 #include "llvm/Support/raw_ostream.h"
48 #define DEBUG_TYPE "r600cf"
56 FIRST_NON_WQM_PUSH = 2,
57 FIRST_NON_WQM_PUSH_W_FULL_ENTRY = 3
60 const R600Subtarget *ST;
61 std::vector<StackItem> BranchStack;
62 std::vector<StackItem> LoopStack;
63 unsigned MaxStackSize;
64 unsigned CurrentEntries = 0;
65 unsigned CurrentSubEntries = 0;
67 CFStack(const R600Subtarget *st, CallingConv::ID cc) : ST(st),
68 // We need to reserve a stack entry for CALL_FS in vertex shaders.
69 MaxStackSize(cc == CallingConv::AMDGPU_VS ? 1 : 0) {}
71 unsigned getLoopDepth();
72 bool branchStackContains(CFStack::StackItem);
73 bool requiresWorkAroundForInst(unsigned Opcode);
74 unsigned getSubEntrySize(CFStack::StackItem Item);
75 void updateMaxStackSize();
76 void pushBranch(unsigned Opcode, bool isWQM = false);
82 unsigned CFStack::getLoopDepth() {
83 return LoopStack.size();
86 bool CFStack::branchStackContains(CFStack::StackItem Item) {
87 for (std::vector<CFStack::StackItem>::const_iterator I = BranchStack.begin(),
88 E = BranchStack.end(); I != E; ++I) {
95 bool CFStack::requiresWorkAroundForInst(unsigned Opcode) {
96 if (Opcode == R600::CF_ALU_PUSH_BEFORE && ST->hasCaymanISA() &&
100 if (!ST->hasCFAluBug())
104 default: return false;
105 case R600::CF_ALU_PUSH_BEFORE:
106 case R600::CF_ALU_ELSE_AFTER:
107 case R600::CF_ALU_BREAK:
108 case R600::CF_ALU_CONTINUE:
109 if (CurrentSubEntries == 0)
111 if (ST->getWavefrontSize() == 64) {
112 // We are being conservative here. We only require this work-around if
113 // CurrentSubEntries > 3 &&
114 // (CurrentSubEntries % 4 == 3 || CurrentSubEntries % 4 == 0)
116 // We have to be conservative, because we don't know for certain that
117 // our stack allocation algorithm for Evergreen/NI is correct. Applying this
118 // work-around when CurrentSubEntries > 3 allows us to over-allocate stack
119 // resources without any problems.
120 return CurrentSubEntries > 3;
122 assert(ST->getWavefrontSize() == 32);
123 // We are being conservative here. We only require the work-around if
124 // CurrentSubEntries > 7 &&
125 // (CurrentSubEntries % 8 == 7 || CurrentSubEntries % 8 == 0)
126 // See the comment on the wavefront size == 64 case for why we are
127 // being conservative.
128 return CurrentSubEntries > 7;
133 unsigned CFStack::getSubEntrySize(CFStack::StackItem Item) {
137 case CFStack::FIRST_NON_WQM_PUSH:
138 assert(!ST->hasCaymanISA());
139 if (ST->getGeneration() <= AMDGPUSubtarget::R700) {
140 // +1 For the push operation.
141 // +2 Extra space required.
144 // Some documentation says that this is not necessary on Evergreen,
145 // but experimentation has show that we need to allocate 1 extra
146 // sub-entry for the first non-WQM push.
147 // +1 For the push operation.
148 // +1 Extra space required.
151 case CFStack::FIRST_NON_WQM_PUSH_W_FULL_ENTRY:
152 assert(ST->getGeneration() >= AMDGPUSubtarget::EVERGREEN);
153 // +1 For the push operation.
154 // +1 Extra space required.
156 case CFStack::SUB_ENTRY:
161 void CFStack::updateMaxStackSize() {
162 unsigned CurrentStackSize = CurrentEntries + divideCeil(CurrentSubEntries, 4);
163 MaxStackSize = std::max(CurrentStackSize, MaxStackSize);
166 void CFStack::pushBranch(unsigned Opcode, bool isWQM) {
167 CFStack::StackItem Item = CFStack::ENTRY;
169 case R600::CF_PUSH_EG:
170 case R600::CF_ALU_PUSH_BEFORE:
172 if (!ST->hasCaymanISA() &&
173 !branchStackContains(CFStack::FIRST_NON_WQM_PUSH))
174 Item = CFStack::FIRST_NON_WQM_PUSH; // May not be required on Evergreen/NI
176 // CFStack::getSubEntrySize()
177 else if (CurrentEntries > 0 &&
178 ST->getGeneration() > AMDGPUSubtarget::EVERGREEN &&
179 !ST->hasCaymanISA() &&
180 !branchStackContains(CFStack::FIRST_NON_WQM_PUSH_W_FULL_ENTRY))
181 Item = CFStack::FIRST_NON_WQM_PUSH_W_FULL_ENTRY;
183 Item = CFStack::SUB_ENTRY;
185 Item = CFStack::ENTRY;
188 BranchStack.push_back(Item);
189 if (Item == CFStack::ENTRY)
192 CurrentSubEntries += getSubEntrySize(Item);
193 updateMaxStackSize();
196 void CFStack::pushLoop() {
197 LoopStack.push_back(CFStack::ENTRY);
199 updateMaxStackSize();
202 void CFStack::popBranch() {
203 CFStack::StackItem Top = BranchStack.back();
204 if (Top == CFStack::ENTRY)
207 CurrentSubEntries-= getSubEntrySize(Top);
208 BranchStack.pop_back();
211 void CFStack::popLoop() {
213 LoopStack.pop_back();
216 class R600ControlFlowFinalizer : public MachineFunctionPass {
218 using ClauseFile = std::pair<MachineInstr *, std::vector<MachineInstr *>>;
220 enum ControlFlowInstruction {
234 const R600InstrInfo *TII = nullptr;
235 const R600RegisterInfo *TRI = nullptr;
236 unsigned MaxFetchInst;
237 const R600Subtarget *ST = nullptr;
239 bool IsTrivialInst(MachineInstr &MI) const {
240 switch (MI.getOpcode()) {
249 const MCInstrDesc &getHWInstrDesc(ControlFlowInstruction CFI) const {
251 bool isEg = (ST->getGeneration() >= AMDGPUSubtarget::EVERGREEN);
254 Opcode = isEg ? R600::CF_TC_EG : R600::CF_TC_R600;
257 Opcode = isEg ? R600::CF_VC_EG : R600::CF_VC_R600;
260 Opcode = isEg ? R600::CF_CALL_FS_EG : R600::CF_CALL_FS_R600;
263 Opcode = isEg ? R600::WHILE_LOOP_EG : R600::WHILE_LOOP_R600;
266 Opcode = isEg ? R600::END_LOOP_EG : R600::END_LOOP_R600;
269 Opcode = isEg ? R600::LOOP_BREAK_EG : R600::LOOP_BREAK_R600;
271 case CF_LOOP_CONTINUE:
272 Opcode = isEg ? R600::CF_CONTINUE_EG : R600::CF_CONTINUE_R600;
275 Opcode = isEg ? R600::CF_JUMP_EG : R600::CF_JUMP_R600;
278 Opcode = isEg ? R600::CF_ELSE_EG : R600::CF_ELSE_R600;
281 Opcode = isEg ? R600::POP_EG : R600::POP_R600;
284 if (ST->hasCaymanISA()) {
285 Opcode = R600::CF_END_CM;
288 Opcode = isEg ? R600::CF_END_EG : R600::CF_END_R600;
291 assert (Opcode && "No opcode selected");
292 return TII->get(Opcode);
295 bool isCompatibleWithClause(const MachineInstr &MI,
296 std::set<unsigned> &DstRegs) const {
297 unsigned DstMI, SrcMI;
298 for (MachineInstr::const_mop_iterator I = MI.operands_begin(),
299 E = MI.operands_end();
301 const MachineOperand &MO = *I;
305 Register Reg = MO.getReg();
306 if (R600::R600_Reg128RegClass.contains(Reg))
309 DstMI = TRI->getMatchingSuperReg(Reg,
310 R600RegisterInfo::getSubRegFromChannel(TRI->getHWRegChan(Reg)),
311 &R600::R600_Reg128RegClass);
314 Register Reg = MO.getReg();
315 if (R600::R600_Reg128RegClass.contains(Reg))
318 SrcMI = TRI->getMatchingSuperReg(Reg,
319 R600RegisterInfo::getSubRegFromChannel(TRI->getHWRegChan(Reg)),
320 &R600::R600_Reg128RegClass);
323 if ((DstRegs.find(SrcMI) == DstRegs.end())) {
324 DstRegs.insert(DstMI);
331 MakeFetchClause(MachineBasicBlock &MBB, MachineBasicBlock::iterator &I)
333 MachineBasicBlock::iterator ClauseHead = I;
334 std::vector<MachineInstr *> ClauseContent;
335 unsigned AluInstCount = 0;
336 bool IsTex = TII->usesTextureCache(*ClauseHead);
337 std::set<unsigned> DstRegs;
338 for (MachineBasicBlock::iterator E = MBB.end(); I != E; ++I) {
339 if (IsTrivialInst(*I))
341 if (AluInstCount >= MaxFetchInst)
343 if ((IsTex && !TII->usesTextureCache(*I)) ||
344 (!IsTex && !TII->usesVertexCache(*I)))
346 if (!isCompatibleWithClause(*I, DstRegs))
349 ClauseContent.push_back(&*I);
351 MachineInstr *MIb = BuildMI(MBB, ClauseHead, MBB.findDebugLoc(ClauseHead),
352 getHWInstrDesc(IsTex?CF_TC:CF_VC))
354 .addImm(AluInstCount - 1); // COUNT
355 return ClauseFile(MIb, std::move(ClauseContent));
358 void getLiteral(MachineInstr &MI, std::vector<MachineOperand *> &Lits) const {
359 static const unsigned LiteralRegs[] = {
365 const SmallVector<std::pair<MachineOperand *, int64_t>, 3> Srcs =
367 for (const auto &Src:Srcs) {
368 if (Src.first->getReg() != R600::ALU_LITERAL_X)
370 int64_t Imm = Src.second;
371 std::vector<MachineOperand *>::iterator It =
372 llvm::find_if(Lits, [&](MachineOperand *val) {
373 return val->isImm() && (val->getImm() == Imm);
376 // Get corresponding Operand
377 MachineOperand &Operand = MI.getOperand(
378 TII->getOperandIdx(MI.getOpcode(), R600::OpName::literal));
380 if (It != Lits.end()) {
381 // Reuse existing literal reg
382 unsigned Index = It - Lits.begin();
383 Src.first->setReg(LiteralRegs[Index]);
385 // Allocate new literal reg
386 assert(Lits.size() < 4 && "Too many literals in Instruction Group");
387 Src.first->setReg(LiteralRegs[Lits.size()]);
388 Lits.push_back(&Operand);
393 MachineBasicBlock::iterator insertLiterals(
394 MachineBasicBlock::iterator InsertPos,
395 const std::vector<unsigned> &Literals) const {
396 MachineBasicBlock *MBB = InsertPos->getParent();
397 for (unsigned i = 0, e = Literals.size(); i < e; i+=2) {
398 unsigned LiteralPair0 = Literals[i];
399 unsigned LiteralPair1 = (i + 1 < e)?Literals[i + 1]:0;
400 InsertPos = BuildMI(MBB, InsertPos->getDebugLoc(),
401 TII->get(R600::LITERALS))
402 .addImm(LiteralPair0)
403 .addImm(LiteralPair1);
409 MakeALUClause(MachineBasicBlock &MBB, MachineBasicBlock::iterator &I)
411 MachineInstr &ClauseHead = *I;
412 std::vector<MachineInstr *> ClauseContent;
414 for (MachineBasicBlock::instr_iterator E = MBB.instr_end(); I != E;) {
415 if (IsTrivialInst(*I)) {
419 if (!I->isBundle() && !TII->isALUInstr(I->getOpcode()))
421 std::vector<MachineOperand *>Literals;
423 MachineInstr &DeleteMI = *I;
424 MachineBasicBlock::instr_iterator BI = I.getInstrIterator();
425 while (++BI != E && BI->isBundledWithPred()) {
426 BI->unbundleFromPred();
427 for (MachineOperand &MO : BI->operands()) {
428 if (MO.isReg() && MO.isInternalRead())
429 MO.setIsInternalRead(false);
431 getLiteral(*BI, Literals);
432 ClauseContent.push_back(&*BI);
435 DeleteMI.eraseFromParent();
437 getLiteral(*I, Literals);
438 ClauseContent.push_back(&*I);
441 for (unsigned i = 0, e = Literals.size(); i < e; i += 2) {
442 MachineInstrBuilder MILit = BuildMI(MBB, I, I->getDebugLoc(),
443 TII->get(R600::LITERALS));
444 if (Literals[i]->isImm()) {
445 MILit.addImm(Literals[i]->getImm());
447 MILit.addGlobalAddress(Literals[i]->getGlobal(),
448 Literals[i]->getOffset());
451 if (Literals[i + 1]->isImm()) {
452 MILit.addImm(Literals[i + 1]->getImm());
454 MILit.addGlobalAddress(Literals[i + 1]->getGlobal(),
455 Literals[i + 1]->getOffset());
459 ClauseContent.push_back(MILit);
462 assert(ClauseContent.size() < 128 && "ALU clause is too big");
463 ClauseHead.getOperand(7).setImm(ClauseContent.size() - 1);
464 return ClauseFile(&ClauseHead, std::move(ClauseContent));
467 void EmitFetchClause(MachineBasicBlock::iterator InsertPos,
468 const DebugLoc &DL, ClauseFile &Clause,
470 CounterPropagateAddr(*Clause.first, CfCount);
471 MachineBasicBlock *BB = Clause.first->getParent();
472 BuildMI(BB, DL, TII->get(R600::FETCH_CLAUSE)).addImm(CfCount);
473 for (unsigned i = 0, e = Clause.second.size(); i < e; ++i) {
474 BB->splice(InsertPos, BB, Clause.second[i]);
476 CfCount += 2 * Clause.second.size();
479 void EmitALUClause(MachineBasicBlock::iterator InsertPos, const DebugLoc &DL,
480 ClauseFile &Clause, unsigned &CfCount) {
481 Clause.first->getOperand(0).setImm(0);
482 CounterPropagateAddr(*Clause.first, CfCount);
483 MachineBasicBlock *BB = Clause.first->getParent();
484 BuildMI(BB, DL, TII->get(R600::ALU_CLAUSE)).addImm(CfCount);
485 for (unsigned i = 0, e = Clause.second.size(); i < e; ++i) {
486 BB->splice(InsertPos, BB, Clause.second[i]);
488 CfCount += Clause.second.size();
491 void CounterPropagateAddr(MachineInstr &MI, unsigned Addr) const {
492 MI.getOperand(0).setImm(Addr + MI.getOperand(0).getImm());
494 void CounterPropagateAddr(const std::set<MachineInstr *> &MIs,
495 unsigned Addr) const {
496 for (MachineInstr *MI : MIs) {
497 CounterPropagateAddr(*MI, Addr);
504 R600ControlFlowFinalizer() : MachineFunctionPass(ID) {}
506 bool runOnMachineFunction(MachineFunction &MF) override {
507 ST = &MF.getSubtarget<R600Subtarget>();
508 MaxFetchInst = ST->getTexVTXClauseSize();
509 TII = ST->getInstrInfo();
510 TRI = ST->getRegisterInfo();
512 R600MachineFunctionInfo *MFI = MF.getInfo<R600MachineFunctionInfo>();
514 CFStack CFStack(ST, MF.getFunction().getCallingConv());
515 for (MachineFunction::iterator MB = MF.begin(), ME = MF.end(); MB != ME;
517 MachineBasicBlock &MBB = *MB;
518 unsigned CfCount = 0;
519 std::vector<std::pair<unsigned, std::set<MachineInstr *>>> LoopStack;
520 std::vector<MachineInstr * > IfThenElseStack;
521 if (MF.getFunction().getCallingConv() == CallingConv::AMDGPU_VS) {
522 BuildMI(MBB, MBB.begin(), MBB.findDebugLoc(MBB.begin()),
523 getHWInstrDesc(CF_CALL_FS));
526 std::vector<ClauseFile> FetchClauses, AluClauses;
527 std::vector<MachineInstr *> LastAlu(1);
528 std::vector<MachineInstr *> ToPopAfter;
530 for (MachineBasicBlock::iterator I = MBB.begin(), E = MBB.end();
532 if (TII->usesTextureCache(*I) || TII->usesVertexCache(*I)) {
533 LLVM_DEBUG(dbgs() << CfCount << ":"; I->dump(););
534 FetchClauses.push_back(MakeFetchClause(MBB, I));
536 LastAlu.back() = nullptr;
540 MachineBasicBlock::iterator MI = I;
541 if (MI->getOpcode() != R600::ENDIF)
542 LastAlu.back() = nullptr;
543 if (MI->getOpcode() == R600::CF_ALU)
544 LastAlu.back() = &*MI;
546 bool RequiresWorkAround =
547 CFStack.requiresWorkAroundForInst(MI->getOpcode());
548 switch (MI->getOpcode()) {
549 case R600::CF_ALU_PUSH_BEFORE:
550 if (RequiresWorkAround) {
552 << "Applying bug work-around for ALU_PUSH_BEFORE\n");
553 BuildMI(MBB, MI, MBB.findDebugLoc(MI), TII->get(R600::CF_PUSH_EG))
556 MI->setDesc(TII->get(R600::CF_ALU));
558 CFStack.pushBranch(R600::CF_PUSH_EG);
560 CFStack.pushBranch(R600::CF_ALU_PUSH_BEFORE);
564 AluClauses.push_back(MakeALUClause(MBB, I));
565 LLVM_DEBUG(dbgs() << CfCount << ":"; MI->dump(););
568 case R600::WHILELOOP: {
570 MachineInstr *MIb = BuildMI(MBB, MI, MBB.findDebugLoc(MI),
571 getHWInstrDesc(CF_WHILE_LOOP))
573 std::pair<unsigned, std::set<MachineInstr *>> Pair(CfCount,
574 std::set<MachineInstr *>());
575 Pair.second.insert(MIb);
576 LoopStack.push_back(std::move(Pair));
577 MI->eraseFromParent();
581 case R600::ENDLOOP: {
583 std::pair<unsigned, std::set<MachineInstr *>> Pair =
584 std::move(LoopStack.back());
585 LoopStack.pop_back();
586 CounterPropagateAddr(Pair.second, CfCount);
587 BuildMI(MBB, MI, MBB.findDebugLoc(MI), getHWInstrDesc(CF_END_LOOP))
588 .addImm(Pair.first + 1);
589 MI->eraseFromParent();
593 case R600::IF_PREDICATE_SET: {
594 LastAlu.push_back(nullptr);
595 MachineInstr *MIb = BuildMI(MBB, MI, MBB.findDebugLoc(MI),
596 getHWInstrDesc(CF_JUMP))
599 IfThenElseStack.push_back(MIb);
600 LLVM_DEBUG(dbgs() << CfCount << ":"; MIb->dump(););
601 MI->eraseFromParent();
606 MachineInstr * JumpInst = IfThenElseStack.back();
607 IfThenElseStack.pop_back();
608 CounterPropagateAddr(*JumpInst, CfCount);
609 MachineInstr *MIb = BuildMI(MBB, MI, MBB.findDebugLoc(MI),
610 getHWInstrDesc(CF_ELSE))
613 LLVM_DEBUG(dbgs() << CfCount << ":"; MIb->dump(););
614 IfThenElseStack.push_back(MIb);
615 MI->eraseFromParent();
621 if (LastAlu.back()) {
622 ToPopAfter.push_back(LastAlu.back());
624 MachineInstr *MIb = BuildMI(MBB, MI, MBB.findDebugLoc(MI),
625 getHWInstrDesc(CF_POP))
629 LLVM_DEBUG(dbgs() << CfCount << ":"; MIb->dump(););
633 MachineInstr *IfOrElseInst = IfThenElseStack.back();
634 IfThenElseStack.pop_back();
635 CounterPropagateAddr(*IfOrElseInst, CfCount);
636 IfOrElseInst->getOperand(1).setImm(1);
638 MI->eraseFromParent();
643 MachineInstr *MIb = BuildMI(MBB, MI, MBB.findDebugLoc(MI),
644 getHWInstrDesc(CF_LOOP_BREAK))
646 LoopStack.back().second.insert(MIb);
647 MI->eraseFromParent();
650 case R600::CONTINUE: {
651 MachineInstr *MIb = BuildMI(MBB, MI, MBB.findDebugLoc(MI),
652 getHWInstrDesc(CF_LOOP_CONTINUE))
654 LoopStack.back().second.insert(MIb);
655 MI->eraseFromParent();
660 DebugLoc DL = MBB.findDebugLoc(MI);
661 BuildMI(MBB, MI, DL, getHWInstrDesc(CF_END));
664 BuildMI(MBB, I, DL, TII->get(R600::PAD));
667 MI->eraseFromParent();
668 for (unsigned i = 0, e = FetchClauses.size(); i < e; i++)
669 EmitFetchClause(I, DL, FetchClauses[i], CfCount);
670 for (unsigned i = 0, e = AluClauses.size(); i < e; i++)
671 EmitALUClause(I, DL, AluClauses[i], CfCount);
675 if (TII->isExport(MI->getOpcode())) {
676 LLVM_DEBUG(dbgs() << CfCount << ":"; MI->dump(););
682 for (unsigned i = 0, e = ToPopAfter.size(); i < e; ++i) {
683 MachineInstr *Alu = ToPopAfter[i];
684 BuildMI(MBB, Alu, MBB.findDebugLoc((MachineBasicBlock::iterator)Alu),
685 TII->get(R600::CF_ALU_POP_AFTER))
686 .addImm(Alu->getOperand(0).getImm())
687 .addImm(Alu->getOperand(1).getImm())
688 .addImm(Alu->getOperand(2).getImm())
689 .addImm(Alu->getOperand(3).getImm())
690 .addImm(Alu->getOperand(4).getImm())
691 .addImm(Alu->getOperand(5).getImm())
692 .addImm(Alu->getOperand(6).getImm())
693 .addImm(Alu->getOperand(7).getImm())
694 .addImm(Alu->getOperand(8).getImm());
695 Alu->eraseFromParent();
697 MFI->CFStackSize = CFStack.MaxStackSize;
703 StringRef getPassName() const override {
704 return "R600 Control Flow Finalizer Pass";
708 } // end anonymous namespace
710 INITIALIZE_PASS_BEGIN(R600ControlFlowFinalizer, DEBUG_TYPE,
711 "R600 Control Flow Finalizer", false, false)
712 INITIALIZE_PASS_END(R600ControlFlowFinalizer, DEBUG_TYPE,
713 "R600 Control Flow Finalizer", false, false)
715 char R600ControlFlowFinalizer::ID = 0;
717 char &llvm::R600ControlFlowFinalizerID = R600ControlFlowFinalizer::ID;
719 FunctionPass *llvm::createR600ControlFlowFinalizer() {
720 return new R600ControlFlowFinalizer();