1 //===- SPIRVInstructionSelector.cpp ------------------------------*- C++ -*-==//
2 //
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
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file implements the targeting of the InstructionSelector class for
10 // SPIRV.
11 // TODO: This should be generated by TableGen.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "SPIRV.h"
16 #include "SPIRVGlobalRegistry.h"
17 #include "SPIRVInstrInfo.h"
18 #include "SPIRVRegisterBankInfo.h"
19 #include "SPIRVRegisterInfo.h"
20 #include "SPIRVTargetMachine.h"
21 #include "SPIRVUtils.h"
22 #include "llvm/ADT/APFloat.h"
23 #include "llvm/CodeGen/GlobalISel/InstructionSelector.h"
24 #include "llvm/CodeGen/GlobalISel/InstructionSelectorImpl.h"
25 #include "llvm/CodeGen/MachineInstrBuilder.h"
26 #include "llvm/CodeGen/MachineRegisterInfo.h"
27 #include "llvm/Support/Debug.h"
28 
29 #define DEBUG_TYPE "spirv-isel"
30 
31 using namespace llvm;
32 
33 namespace {
34 
35 #define GET_GLOBALISEL_PREDICATE_BITSET
36 #include "SPIRVGenGlobalISel.inc"
37 #undef GET_GLOBALISEL_PREDICATE_BITSET
38 
39 class SPIRVInstructionSelector : public InstructionSelector {
40   const SPIRVSubtarget &STI;
41   const SPIRVInstrInfo &TII;
42   const SPIRVRegisterInfo &TRI;
43   const RegisterBankInfo &RBI;
44   SPIRVGlobalRegistry &GR;
45   MachineRegisterInfo *MRI;
46 
47 public:
48   SPIRVInstructionSelector(const SPIRVTargetMachine &TM,
49                            const SPIRVSubtarget &ST,
50                            const RegisterBankInfo &RBI);
51   void setupMF(MachineFunction &MF, GISelKnownBits *KB,
52                CodeGenCoverage &CoverageInfo, ProfileSummaryInfo *PSI,
53                BlockFrequencyInfo *BFI) override;
54   // Common selection code. Instruction-specific selection occurs in spvSelect.
55   bool select(MachineInstr &I) override;
56   static const char *getName() { return DEBUG_TYPE; }
57 
58 #define GET_GLOBALISEL_PREDICATES_DECL
59 #include "SPIRVGenGlobalISel.inc"
60 #undef GET_GLOBALISEL_PREDICATES_DECL
61 
62 #define GET_GLOBALISEL_TEMPORARIES_DECL
63 #include "SPIRVGenGlobalISel.inc"
64 #undef GET_GLOBALISEL_TEMPORARIES_DECL
65 
66 private:
67   // tblgen-erated 'select' implementation, used as the initial selector for
68   // the patterns that don't require complex C++.
69   bool selectImpl(MachineInstr &I, CodeGenCoverage &CoverageInfo) const;
70 
71   // All instruction-specific selection that didn't happen in "select()".
72   // Is basically a large Switch/Case delegating to all other select method.
73   bool spvSelect(Register ResVReg, const SPIRVType *ResType,
74                  MachineInstr &I) const;
75 
76   bool selectGlobalValue(Register ResVReg, MachineInstr &I,
77                          const MachineInstr *Init = nullptr) const;
78 
79   bool selectUnOpWithSrc(Register ResVReg, const SPIRVType *ResType,
80                          MachineInstr &I, Register SrcReg,
81                          unsigned Opcode) const;
82   bool selectUnOp(Register ResVReg, const SPIRVType *ResType, MachineInstr &I,
83                   unsigned Opcode) const;
84 
85   bool selectLoad(Register ResVReg, const SPIRVType *ResType,
86                   MachineInstr &I) const;
87   bool selectStore(MachineInstr &I) const;
88 
89   bool selectMemOperation(Register ResVReg, MachineInstr &I) const;
90 
91   bool selectAtomicRMW(Register ResVReg, const SPIRVType *ResType,
92                        MachineInstr &I, unsigned NewOpcode) const;
93 
94   bool selectAtomicCmpXchg(Register ResVReg, const SPIRVType *ResType,
95                            MachineInstr &I) const;
96 
97   bool selectFence(MachineInstr &I) const;
98 
99   bool selectAddrSpaceCast(Register ResVReg, const SPIRVType *ResType,
100                            MachineInstr &I) const;
101 
102   bool selectBitreverse(Register ResVReg, const SPIRVType *ResType,
103                         MachineInstr &I) const;
104 
105   bool selectConstVector(Register ResVReg, const SPIRVType *ResType,
106                          MachineInstr &I) const;
107 
108   bool selectCmp(Register ResVReg, const SPIRVType *ResType,
109                  unsigned comparisonOpcode, MachineInstr &I) const;
110 
111   bool selectICmp(Register ResVReg, const SPIRVType *ResType,
112                   MachineInstr &I) const;
113   bool selectFCmp(Register ResVReg, const SPIRVType *ResType,
114                   MachineInstr &I) const;
115 
116   void renderImm32(MachineInstrBuilder &MIB, const MachineInstr &I,
117                    int OpIdx) const;
118   void renderFImm32(MachineInstrBuilder &MIB, const MachineInstr &I,
119                     int OpIdx) const;
120 
121   bool selectConst(Register ResVReg, const SPIRVType *ResType, const APInt &Imm,
122                    MachineInstr &I) const;
123 
124   bool selectSelect(Register ResVReg, const SPIRVType *ResType, MachineInstr &I,
125                     bool IsSigned) const;
126   bool selectIToF(Register ResVReg, const SPIRVType *ResType, MachineInstr &I,
127                   bool IsSigned, unsigned Opcode) const;
128   bool selectExt(Register ResVReg, const SPIRVType *ResType, MachineInstr &I,
129                  bool IsSigned) const;
130 
131   bool selectTrunc(Register ResVReg, const SPIRVType *ResType,
132                    MachineInstr &I) const;
133 
134   bool selectIntToBool(Register IntReg, Register ResVReg,
135                        const SPIRVType *intTy, const SPIRVType *boolTy,
136                        MachineInstr &I) const;
137 
138   bool selectOpUndef(Register ResVReg, const SPIRVType *ResType,
139                      MachineInstr &I) const;
140   bool selectIntrinsic(Register ResVReg, const SPIRVType *ResType,
141                        MachineInstr &I) const;
142 
143   bool selectFrameIndex(Register ResVReg, const SPIRVType *ResType,
144                         MachineInstr &I) const;
145 
146   bool selectBranch(MachineInstr &I) const;
147   bool selectBranchCond(MachineInstr &I) const;
148 
149   bool selectPhi(Register ResVReg, const SPIRVType *ResType,
150                  MachineInstr &I) const;
151 
152   Register buildI32Constant(uint32_t Val, MachineInstr &I,
153                             const SPIRVType *ResType = nullptr) const;
154 
155   Register buildZerosVal(const SPIRVType *ResType, MachineInstr &I) const;
156   Register buildOnesVal(bool AllOnes, const SPIRVType *ResType,
157                         MachineInstr &I) const;
158 };
159 
160 } // end anonymous namespace
161 
162 #define GET_GLOBALISEL_IMPL
163 #include "SPIRVGenGlobalISel.inc"
164 #undef GET_GLOBALISEL_IMPL
165 
166 SPIRVInstructionSelector::SPIRVInstructionSelector(const SPIRVTargetMachine &TM,
167                                                    const SPIRVSubtarget &ST,
168                                                    const RegisterBankInfo &RBI)
169     : InstructionSelector(), STI(ST), TII(*ST.getInstrInfo()),
170       TRI(*ST.getRegisterInfo()), RBI(RBI), GR(*ST.getSPIRVGlobalRegistry()),
171 #define GET_GLOBALISEL_PREDICATES_INIT
172 #include "SPIRVGenGlobalISel.inc"
173 #undef GET_GLOBALISEL_PREDICATES_INIT
174 #define GET_GLOBALISEL_TEMPORARIES_INIT
175 #include "SPIRVGenGlobalISel.inc"
176 #undef GET_GLOBALISEL_TEMPORARIES_INIT
177 {
178 }
179 
180 void SPIRVInstructionSelector::setupMF(MachineFunction &MF, GISelKnownBits *KB,
181                                        CodeGenCoverage &CoverageInfo,
182                                        ProfileSummaryInfo *PSI,
183                                        BlockFrequencyInfo *BFI) {
184   MRI = &MF.getRegInfo();
185   GR.setCurrentFunc(MF);
186   InstructionSelector::setupMF(MF, KB, CoverageInfo, PSI, BFI);
187 }
188 
189 // Defined in SPIRVLegalizerInfo.cpp.
190 extern bool isTypeFoldingSupported(unsigned Opcode);
191 
192 bool SPIRVInstructionSelector::select(MachineInstr &I) {
193   assert(I.getParent() && "Instruction should be in a basic block!");
194   assert(I.getParent()->getParent() && "Instruction should be in a function!");
195 
196   Register Opcode = I.getOpcode();
197   // If it's not a GMIR instruction, we've selected it already.
198   if (!isPreISelGenericOpcode(Opcode)) {
199     if (Opcode == SPIRV::ASSIGN_TYPE) { // These pseudos aren't needed any more.
200       auto *Def = MRI->getVRegDef(I.getOperand(1).getReg());
201       if (isTypeFoldingSupported(Def->getOpcode())) {
202         auto Res = selectImpl(I, *CoverageInfo);
203         assert(Res || Def->getOpcode() == TargetOpcode::G_CONSTANT);
204         if (Res)
205           return Res;
206       }
207       MRI->replaceRegWith(I.getOperand(1).getReg(), I.getOperand(0).getReg());
208       I.removeFromParent();
209     } else if (I.getNumDefs() == 1) {
210       // Make all vregs 32 bits (for SPIR-V IDs).
211       MRI->setType(I.getOperand(0).getReg(), LLT::scalar(32));
212     }
213     return true;
214   }
215 
216   if (I.getNumOperands() != I.getNumExplicitOperands()) {
217     LLVM_DEBUG(errs() << "Generic instr has unexpected implicit operands\n");
218     return false;
219   }
220 
221   // Common code for getting return reg+type, and removing selected instr
222   // from parent occurs here. Instr-specific selection happens in spvSelect().
223   bool HasDefs = I.getNumDefs() > 0;
224   Register ResVReg = HasDefs ? I.getOperand(0).getReg() : Register(0);
225   SPIRVType *ResType = HasDefs ? GR.getSPIRVTypeForVReg(ResVReg) : nullptr;
226   assert(!HasDefs || ResType || I.getOpcode() == TargetOpcode::G_GLOBAL_VALUE);
227   if (spvSelect(ResVReg, ResType, I)) {
228     if (HasDefs) // Make all vregs 32 bits (for SPIR-V IDs).
229       MRI->setType(ResVReg, LLT::scalar(32));
230     I.removeFromParent();
231     return true;
232   }
233   return false;
234 }
235 
236 bool SPIRVInstructionSelector::spvSelect(Register ResVReg,
237                                          const SPIRVType *ResType,
238                                          MachineInstr &I) const {
239   assert(!isTypeFoldingSupported(I.getOpcode()) ||
240          I.getOpcode() == TargetOpcode::G_CONSTANT);
241   const unsigned Opcode = I.getOpcode();
242   switch (Opcode) {
243   case TargetOpcode::G_CONSTANT:
244     return selectConst(ResVReg, ResType, I.getOperand(1).getCImm()->getValue(),
245                        I);
246   case TargetOpcode::G_GLOBAL_VALUE:
247     return selectGlobalValue(ResVReg, I);
248   case TargetOpcode::G_IMPLICIT_DEF:
249     return selectOpUndef(ResVReg, ResType, I);
250 
251   case TargetOpcode::G_INTRINSIC_W_SIDE_EFFECTS:
252     return selectIntrinsic(ResVReg, ResType, I);
253   case TargetOpcode::G_BITREVERSE:
254     return selectBitreverse(ResVReg, ResType, I);
255 
256   case TargetOpcode::G_BUILD_VECTOR:
257     return selectConstVector(ResVReg, ResType, I);
258 
259   case TargetOpcode::G_SHUFFLE_VECTOR: {
260     MachineBasicBlock &BB = *I.getParent();
261     auto MIB = BuildMI(BB, I, I.getDebugLoc(), TII.get(SPIRV::OpVectorShuffle))
262                    .addDef(ResVReg)
263                    .addUse(GR.getSPIRVTypeID(ResType))
264                    .addUse(I.getOperand(1).getReg())
265                    .addUse(I.getOperand(2).getReg());
266     for (auto V : I.getOperand(3).getShuffleMask())
267       MIB.addImm(V);
268     return MIB.constrainAllUses(TII, TRI, RBI);
269   }
270   case TargetOpcode::G_MEMMOVE:
271   case TargetOpcode::G_MEMCPY:
272     return selectMemOperation(ResVReg, I);
273 
274   case TargetOpcode::G_ICMP:
275     return selectICmp(ResVReg, ResType, I);
276   case TargetOpcode::G_FCMP:
277     return selectFCmp(ResVReg, ResType, I);
278 
279   case TargetOpcode::G_FRAME_INDEX:
280     return selectFrameIndex(ResVReg, ResType, I);
281 
282   case TargetOpcode::G_LOAD:
283     return selectLoad(ResVReg, ResType, I);
284   case TargetOpcode::G_STORE:
285     return selectStore(I);
286 
287   case TargetOpcode::G_BR:
288     return selectBranch(I);
289   case TargetOpcode::G_BRCOND:
290     return selectBranchCond(I);
291 
292   case TargetOpcode::G_PHI:
293     return selectPhi(ResVReg, ResType, I);
294 
295   case TargetOpcode::G_FPTOSI:
296     return selectUnOp(ResVReg, ResType, I, SPIRV::OpConvertFToS);
297   case TargetOpcode::G_FPTOUI:
298     return selectUnOp(ResVReg, ResType, I, SPIRV::OpConvertFToU);
299 
300   case TargetOpcode::G_SITOFP:
301     return selectIToF(ResVReg, ResType, I, true, SPIRV::OpConvertSToF);
302   case TargetOpcode::G_UITOFP:
303     return selectIToF(ResVReg, ResType, I, false, SPIRV::OpConvertUToF);
304 
305   case TargetOpcode::G_CTPOP:
306     return selectUnOp(ResVReg, ResType, I, SPIRV::OpBitCount);
307 
308   case TargetOpcode::G_SEXT:
309     return selectExt(ResVReg, ResType, I, true);
310   case TargetOpcode::G_ANYEXT:
311   case TargetOpcode::G_ZEXT:
312     return selectExt(ResVReg, ResType, I, false);
313   case TargetOpcode::G_TRUNC:
314     return selectTrunc(ResVReg, ResType, I);
315   case TargetOpcode::G_FPTRUNC:
316   case TargetOpcode::G_FPEXT:
317     return selectUnOp(ResVReg, ResType, I, SPIRV::OpFConvert);
318 
319   case TargetOpcode::G_PTRTOINT:
320     return selectUnOp(ResVReg, ResType, I, SPIRV::OpConvertPtrToU);
321   case TargetOpcode::G_INTTOPTR:
322     return selectUnOp(ResVReg, ResType, I, SPIRV::OpConvertUToPtr);
323   case TargetOpcode::G_BITCAST:
324     return selectUnOp(ResVReg, ResType, I, SPIRV::OpBitcast);
325   case TargetOpcode::G_ADDRSPACE_CAST:
326     return selectAddrSpaceCast(ResVReg, ResType, I);
327 
328   case TargetOpcode::G_ATOMICRMW_OR:
329     return selectAtomicRMW(ResVReg, ResType, I, SPIRV::OpAtomicOr);
330   case TargetOpcode::G_ATOMICRMW_ADD:
331     return selectAtomicRMW(ResVReg, ResType, I, SPIRV::OpAtomicIAdd);
332   case TargetOpcode::G_ATOMICRMW_AND:
333     return selectAtomicRMW(ResVReg, ResType, I, SPIRV::OpAtomicAnd);
334   case TargetOpcode::G_ATOMICRMW_MAX:
335     return selectAtomicRMW(ResVReg, ResType, I, SPIRV::OpAtomicSMax);
336   case TargetOpcode::G_ATOMICRMW_MIN:
337     return selectAtomicRMW(ResVReg, ResType, I, SPIRV::OpAtomicSMin);
338   case TargetOpcode::G_ATOMICRMW_SUB:
339     return selectAtomicRMW(ResVReg, ResType, I, SPIRV::OpAtomicISub);
340   case TargetOpcode::G_ATOMICRMW_XOR:
341     return selectAtomicRMW(ResVReg, ResType, I, SPIRV::OpAtomicXor);
342   case TargetOpcode::G_ATOMICRMW_UMAX:
343     return selectAtomicRMW(ResVReg, ResType, I, SPIRV::OpAtomicUMax);
344   case TargetOpcode::G_ATOMICRMW_UMIN:
345     return selectAtomicRMW(ResVReg, ResType, I, SPIRV::OpAtomicUMin);
346   case TargetOpcode::G_ATOMICRMW_XCHG:
347     return selectAtomicRMW(ResVReg, ResType, I, SPIRV::OpAtomicExchange);
348   case TargetOpcode::G_ATOMIC_CMPXCHG:
349     return selectAtomicCmpXchg(ResVReg, ResType, I);
350 
351   case TargetOpcode::G_FENCE:
352     return selectFence(I);
353 
354   default:
355     return false;
356   }
357 }
358 
359 bool SPIRVInstructionSelector::selectUnOpWithSrc(Register ResVReg,
360                                                  const SPIRVType *ResType,
361                                                  MachineInstr &I,
362                                                  Register SrcReg,
363                                                  unsigned Opcode) const {
364   return BuildMI(*I.getParent(), I, I.getDebugLoc(), TII.get(Opcode))
365       .addDef(ResVReg)
366       .addUse(GR.getSPIRVTypeID(ResType))
367       .addUse(SrcReg)
368       .constrainAllUses(TII, TRI, RBI);
369 }
370 
371 bool SPIRVInstructionSelector::selectUnOp(Register ResVReg,
372                                           const SPIRVType *ResType,
373                                           MachineInstr &I,
374                                           unsigned Opcode) const {
375   return selectUnOpWithSrc(ResVReg, ResType, I, I.getOperand(1).getReg(),
376                            Opcode);
377 }
378 
379 static SPIRV::MemorySemantics getMemSemantics(AtomicOrdering Ord) {
380   switch (Ord) {
381   case AtomicOrdering::Acquire:
382     return SPIRV::MemorySemantics::Acquire;
383   case AtomicOrdering::Release:
384     return SPIRV::MemorySemantics::Release;
385   case AtomicOrdering::AcquireRelease:
386     return SPIRV::MemorySemantics::AcquireRelease;
387   case AtomicOrdering::SequentiallyConsistent:
388     return SPIRV::MemorySemantics::SequentiallyConsistent;
389   case AtomicOrdering::Unordered:
390   case AtomicOrdering::Monotonic:
391   case AtomicOrdering::NotAtomic:
392     return SPIRV::MemorySemantics::None;
393   }
394 }
395 
396 static SPIRV::Scope getScope(SyncScope::ID Ord) {
397   switch (Ord) {
398   case SyncScope::SingleThread:
399     return SPIRV::Scope::Invocation;
400   case SyncScope::System:
401     return SPIRV::Scope::Device;
402   default:
403     llvm_unreachable("Unsupported synchronization Scope ID.");
404   }
405 }
406 
407 static void addMemoryOperands(MachineMemOperand *MemOp,
408                               MachineInstrBuilder &MIB) {
409   uint32_t SpvMemOp = static_cast<uint32_t>(SPIRV::MemoryOperand::None);
410   if (MemOp->isVolatile())
411     SpvMemOp |= static_cast<uint32_t>(SPIRV::MemoryOperand::Volatile);
412   if (MemOp->isNonTemporal())
413     SpvMemOp |= static_cast<uint32_t>(SPIRV::MemoryOperand::Nontemporal);
414   if (MemOp->getAlign().value())
415     SpvMemOp |= static_cast<uint32_t>(SPIRV::MemoryOperand::Aligned);
416 
417   if (SpvMemOp != static_cast<uint32_t>(SPIRV::MemoryOperand::None)) {
418     MIB.addImm(SpvMemOp);
419     if (SpvMemOp & static_cast<uint32_t>(SPIRV::MemoryOperand::Aligned))
420       MIB.addImm(MemOp->getAlign().value());
421   }
422 }
423 
424 static void addMemoryOperands(uint64_t Flags, MachineInstrBuilder &MIB) {
425   uint32_t SpvMemOp = static_cast<uint32_t>(SPIRV::MemoryOperand::None);
426   if (Flags & MachineMemOperand::Flags::MOVolatile)
427     SpvMemOp |= static_cast<uint32_t>(SPIRV::MemoryOperand::Volatile);
428   if (Flags & MachineMemOperand::Flags::MONonTemporal)
429     SpvMemOp |= static_cast<uint32_t>(SPIRV::MemoryOperand::Nontemporal);
430 
431   if (SpvMemOp != static_cast<uint32_t>(SPIRV::MemoryOperand::None))
432     MIB.addImm(SpvMemOp);
433 }
434 
435 bool SPIRVInstructionSelector::selectLoad(Register ResVReg,
436                                           const SPIRVType *ResType,
437                                           MachineInstr &I) const {
438   unsigned OpOffset =
439       I.getOpcode() == TargetOpcode::G_INTRINSIC_W_SIDE_EFFECTS ? 1 : 0;
440   Register Ptr = I.getOperand(1 + OpOffset).getReg();
441   auto MIB = BuildMI(*I.getParent(), I, I.getDebugLoc(), TII.get(SPIRV::OpLoad))
442                  .addDef(ResVReg)
443                  .addUse(GR.getSPIRVTypeID(ResType))
444                  .addUse(Ptr);
445   if (!I.getNumMemOperands()) {
446     assert(I.getOpcode() == TargetOpcode::G_INTRINSIC_W_SIDE_EFFECTS);
447     addMemoryOperands(I.getOperand(2 + OpOffset).getImm(), MIB);
448   } else {
449     addMemoryOperands(*I.memoperands_begin(), MIB);
450   }
451   return MIB.constrainAllUses(TII, TRI, RBI);
452 }
453 
454 bool SPIRVInstructionSelector::selectStore(MachineInstr &I) const {
455   unsigned OpOffset =
456       I.getOpcode() == TargetOpcode::G_INTRINSIC_W_SIDE_EFFECTS ? 1 : 0;
457   Register StoreVal = I.getOperand(0 + OpOffset).getReg();
458   Register Ptr = I.getOperand(1 + OpOffset).getReg();
459   MachineBasicBlock &BB = *I.getParent();
460   auto MIB = BuildMI(BB, I, I.getDebugLoc(), TII.get(SPIRV::OpStore))
461                  .addUse(Ptr)
462                  .addUse(StoreVal);
463   if (!I.getNumMemOperands()) {
464     assert(I.getOpcode() == TargetOpcode::G_INTRINSIC_W_SIDE_EFFECTS);
465     addMemoryOperands(I.getOperand(2 + OpOffset).getImm(), MIB);
466   } else {
467     addMemoryOperands(*I.memoperands_begin(), MIB);
468   }
469   return MIB.constrainAllUses(TII, TRI, RBI);
470 }
471 
472 bool SPIRVInstructionSelector::selectMemOperation(Register ResVReg,
473                                                   MachineInstr &I) const {
474   MachineBasicBlock &BB = *I.getParent();
475   auto MIB = BuildMI(BB, I, I.getDebugLoc(), TII.get(SPIRV::OpCopyMemorySized))
476                  .addDef(I.getOperand(0).getReg())
477                  .addUse(I.getOperand(1).getReg())
478                  .addUse(I.getOperand(2).getReg());
479   if (I.getNumMemOperands())
480     addMemoryOperands(*I.memoperands_begin(), MIB);
481   bool Result = MIB.constrainAllUses(TII, TRI, RBI);
482   if (ResVReg.isValid() && ResVReg != MIB->getOperand(0).getReg()) {
483     BuildMI(BB, I, I.getDebugLoc(), TII.get(TargetOpcode::COPY), ResVReg)
484         .addUse(MIB->getOperand(0).getReg());
485   }
486   return Result;
487 }
488 
489 bool SPIRVInstructionSelector::selectAtomicRMW(Register ResVReg,
490                                                const SPIRVType *ResType,
491                                                MachineInstr &I,
492                                                unsigned NewOpcode) const {
493   assert(I.hasOneMemOperand());
494   const MachineMemOperand *MemOp = *I.memoperands_begin();
495   uint32_t Scope = static_cast<uint32_t>(getScope(MemOp->getSyncScopeID()));
496   Register ScopeReg = buildI32Constant(Scope, I);
497 
498   Register Ptr = I.getOperand(1).getReg();
499   // TODO: Changed as it's implemented in the translator. See test/atomicrmw.ll
500   // auto ScSem =
501   // getMemSemanticsForStorageClass(GR.getPointerStorageClass(Ptr));
502   AtomicOrdering AO = MemOp->getSuccessOrdering();
503   uint32_t MemSem = static_cast<uint32_t>(getMemSemantics(AO));
504   Register MemSemReg = buildI32Constant(MemSem /*| ScSem*/, I);
505 
506   return BuildMI(*I.getParent(), I, I.getDebugLoc(), TII.get(NewOpcode))
507       .addDef(ResVReg)
508       .addUse(GR.getSPIRVTypeID(ResType))
509       .addUse(Ptr)
510       .addUse(ScopeReg)
511       .addUse(MemSemReg)
512       .addUse(I.getOperand(2).getReg())
513       .constrainAllUses(TII, TRI, RBI);
514 }
515 
516 bool SPIRVInstructionSelector::selectFence(MachineInstr &I) const {
517   AtomicOrdering AO = AtomicOrdering(I.getOperand(0).getImm());
518   uint32_t MemSem = static_cast<uint32_t>(getMemSemantics(AO));
519   Register MemSemReg = buildI32Constant(MemSem, I);
520   SyncScope::ID Ord = SyncScope::ID(I.getOperand(1).getImm());
521   uint32_t Scope = static_cast<uint32_t>(getScope(Ord));
522   Register ScopeReg = buildI32Constant(Scope, I);
523   MachineBasicBlock &BB = *I.getParent();
524   return BuildMI(BB, I, I.getDebugLoc(), TII.get(SPIRV::OpMemoryBarrier))
525       .addUse(ScopeReg)
526       .addUse(MemSemReg)
527       .constrainAllUses(TII, TRI, RBI);
528 }
529 
530 bool SPIRVInstructionSelector::selectAtomicCmpXchg(Register ResVReg,
531                                                    const SPIRVType *ResType,
532                                                    MachineInstr &I) const {
533   assert(I.hasOneMemOperand());
534   const MachineMemOperand *MemOp = *I.memoperands_begin();
535   uint32_t Scope = static_cast<uint32_t>(getScope(MemOp->getSyncScopeID()));
536   Register ScopeReg = buildI32Constant(Scope, I);
537 
538   Register Ptr = I.getOperand(2).getReg();
539   Register Cmp = I.getOperand(3).getReg();
540   Register Val = I.getOperand(4).getReg();
541 
542   SPIRVType *SpvValTy = GR.getSPIRVTypeForVReg(Val);
543   SPIRV::StorageClass SC = GR.getPointerStorageClass(Ptr);
544   uint32_t ScSem = static_cast<uint32_t>(getMemSemanticsForStorageClass(SC));
545   AtomicOrdering AO = MemOp->getSuccessOrdering();
546   uint32_t MemSemEq = static_cast<uint32_t>(getMemSemantics(AO)) | ScSem;
547   Register MemSemEqReg = buildI32Constant(MemSemEq, I);
548   AtomicOrdering FO = MemOp->getFailureOrdering();
549   uint32_t MemSemNeq = static_cast<uint32_t>(getMemSemantics(FO)) | ScSem;
550   Register MemSemNeqReg =
551       MemSemEq == MemSemNeq ? MemSemEqReg : buildI32Constant(MemSemNeq, I);
552   const DebugLoc &DL = I.getDebugLoc();
553   return BuildMI(*I.getParent(), I, DL, TII.get(SPIRV::OpAtomicCompareExchange))
554       .addDef(ResVReg)
555       .addUse(GR.getSPIRVTypeID(SpvValTy))
556       .addUse(Ptr)
557       .addUse(ScopeReg)
558       .addUse(MemSemEqReg)
559       .addUse(MemSemNeqReg)
560       .addUse(Val)
561       .addUse(Cmp)
562       .constrainAllUses(TII, TRI, RBI);
563 }
564 
565 static bool isGenericCastablePtr(SPIRV::StorageClass SC) {
566   switch (SC) {
567   case SPIRV::StorageClass::Workgroup:
568   case SPIRV::StorageClass::CrossWorkgroup:
569   case SPIRV::StorageClass::Function:
570     return true;
571   default:
572     return false;
573   }
574 }
575 
576 // In SPIR-V address space casting can only happen to and from the Generic
577 // storage class. We can also only case Workgroup, CrossWorkgroup, or Function
578 // pointers to and from Generic pointers. As such, we can convert e.g. from
579 // Workgroup to Function by going via a Generic pointer as an intermediary. All
580 // other combinations can only be done by a bitcast, and are probably not safe.
581 bool SPIRVInstructionSelector::selectAddrSpaceCast(Register ResVReg,
582                                                    const SPIRVType *ResType,
583                                                    MachineInstr &I) const {
584   Register SrcPtr = I.getOperand(1).getReg();
585   SPIRVType *SrcPtrTy = GR.getSPIRVTypeForVReg(SrcPtr);
586   SPIRV::StorageClass SrcSC = GR.getPointerStorageClass(SrcPtr);
587   SPIRV::StorageClass DstSC = GR.getPointerStorageClass(ResVReg);
588 
589   // Casting from an eligable pointer to Generic.
590   if (DstSC == SPIRV::StorageClass::Generic && isGenericCastablePtr(SrcSC))
591     return selectUnOp(ResVReg, ResType, I, SPIRV::OpPtrCastToGeneric);
592   // Casting from Generic to an eligable pointer.
593   if (SrcSC == SPIRV::StorageClass::Generic && isGenericCastablePtr(DstSC))
594     return selectUnOp(ResVReg, ResType, I, SPIRV::OpGenericCastToPtr);
595   // Casting between 2 eligable pointers using Generic as an intermediary.
596   if (isGenericCastablePtr(SrcSC) && isGenericCastablePtr(DstSC)) {
597     Register Tmp = MRI->createVirtualRegister(&SPIRV::IDRegClass);
598     SPIRVType *GenericPtrTy = GR.getOrCreateSPIRVPointerType(
599         SrcPtrTy, I, TII, SPIRV::StorageClass::Generic);
600     MachineBasicBlock &BB = *I.getParent();
601     const DebugLoc &DL = I.getDebugLoc();
602     bool Success = BuildMI(BB, I, DL, TII.get(SPIRV::OpPtrCastToGeneric))
603                        .addDef(Tmp)
604                        .addUse(GR.getSPIRVTypeID(GenericPtrTy))
605                        .addUse(SrcPtr)
606                        .constrainAllUses(TII, TRI, RBI);
607     return Success && BuildMI(BB, I, DL, TII.get(SPIRV::OpGenericCastToPtr))
608                           .addDef(ResVReg)
609                           .addUse(GR.getSPIRVTypeID(ResType))
610                           .addUse(Tmp)
611                           .constrainAllUses(TII, TRI, RBI);
612   }
613   // TODO Should this case just be disallowed completely?
614   // We're casting 2 other arbitrary address spaces, so have to bitcast.
615   return selectUnOp(ResVReg, ResType, I, SPIRV::OpBitcast);
616 }
617 
618 static unsigned getFCmpOpcode(unsigned PredNum) {
619   auto Pred = static_cast<CmpInst::Predicate>(PredNum);
620   switch (Pred) {
621   case CmpInst::FCMP_OEQ:
622     return SPIRV::OpFOrdEqual;
623   case CmpInst::FCMP_OGE:
624     return SPIRV::OpFOrdGreaterThanEqual;
625   case CmpInst::FCMP_OGT:
626     return SPIRV::OpFOrdGreaterThan;
627   case CmpInst::FCMP_OLE:
628     return SPIRV::OpFOrdLessThanEqual;
629   case CmpInst::FCMP_OLT:
630     return SPIRV::OpFOrdLessThan;
631   case CmpInst::FCMP_ONE:
632     return SPIRV::OpFOrdNotEqual;
633   case CmpInst::FCMP_ORD:
634     return SPIRV::OpOrdered;
635   case CmpInst::FCMP_UEQ:
636     return SPIRV::OpFUnordEqual;
637   case CmpInst::FCMP_UGE:
638     return SPIRV::OpFUnordGreaterThanEqual;
639   case CmpInst::FCMP_UGT:
640     return SPIRV::OpFUnordGreaterThan;
641   case CmpInst::FCMP_ULE:
642     return SPIRV::OpFUnordLessThanEqual;
643   case CmpInst::FCMP_ULT:
644     return SPIRV::OpFUnordLessThan;
645   case CmpInst::FCMP_UNE:
646     return SPIRV::OpFUnordNotEqual;
647   case CmpInst::FCMP_UNO:
648     return SPIRV::OpUnordered;
649   default:
650     llvm_unreachable("Unknown predicate type for FCmp");
651   }
652 }
653 
654 static unsigned getICmpOpcode(unsigned PredNum) {
655   auto Pred = static_cast<CmpInst::Predicate>(PredNum);
656   switch (Pred) {
657   case CmpInst::ICMP_EQ:
658     return SPIRV::OpIEqual;
659   case CmpInst::ICMP_NE:
660     return SPIRV::OpINotEqual;
661   case CmpInst::ICMP_SGE:
662     return SPIRV::OpSGreaterThanEqual;
663   case CmpInst::ICMP_SGT:
664     return SPIRV::OpSGreaterThan;
665   case CmpInst::ICMP_SLE:
666     return SPIRV::OpSLessThanEqual;
667   case CmpInst::ICMP_SLT:
668     return SPIRV::OpSLessThan;
669   case CmpInst::ICMP_UGE:
670     return SPIRV::OpUGreaterThanEqual;
671   case CmpInst::ICMP_UGT:
672     return SPIRV::OpUGreaterThan;
673   case CmpInst::ICMP_ULE:
674     return SPIRV::OpULessThanEqual;
675   case CmpInst::ICMP_ULT:
676     return SPIRV::OpULessThan;
677   default:
678     llvm_unreachable("Unknown predicate type for ICmp");
679   }
680 }
681 
682 static unsigned getPtrCmpOpcode(unsigned Pred) {
683   switch (static_cast<CmpInst::Predicate>(Pred)) {
684   case CmpInst::ICMP_EQ:
685     return SPIRV::OpPtrEqual;
686   case CmpInst::ICMP_NE:
687     return SPIRV::OpPtrNotEqual;
688   default:
689     llvm_unreachable("Unknown predicate type for pointer comparison");
690   }
691 }
692 
693 // Return the logical operation, or abort if none exists.
694 static unsigned getBoolCmpOpcode(unsigned PredNum) {
695   auto Pred = static_cast<CmpInst::Predicate>(PredNum);
696   switch (Pred) {
697   case CmpInst::ICMP_EQ:
698     return SPIRV::OpLogicalEqual;
699   case CmpInst::ICMP_NE:
700     return SPIRV::OpLogicalNotEqual;
701   default:
702     llvm_unreachable("Unknown predicate type for Bool comparison");
703   }
704 }
705 
706 bool SPIRVInstructionSelector::selectBitreverse(Register ResVReg,
707                                                 const SPIRVType *ResType,
708                                                 MachineInstr &I) const {
709   MachineBasicBlock &BB = *I.getParent();
710   return BuildMI(BB, I, I.getDebugLoc(), TII.get(SPIRV::OpBitReverse))
711       .addDef(ResVReg)
712       .addUse(GR.getSPIRVTypeID(ResType))
713       .addUse(I.getOperand(1).getReg())
714       .constrainAllUses(TII, TRI, RBI);
715 }
716 
717 bool SPIRVInstructionSelector::selectConstVector(Register ResVReg,
718                                                  const SPIRVType *ResType,
719                                                  MachineInstr &I) const {
720   // TODO: only const case is supported for now.
721   assert(std::all_of(
722       I.operands_begin(), I.operands_end(), [this](const MachineOperand &MO) {
723         if (MO.isDef())
724           return true;
725         if (!MO.isReg())
726           return false;
727         SPIRVType *ConstTy = this->MRI->getVRegDef(MO.getReg());
728         assert(ConstTy && ConstTy->getOpcode() == SPIRV::ASSIGN_TYPE &&
729                ConstTy->getOperand(1).isReg());
730         Register ConstReg = ConstTy->getOperand(1).getReg();
731         const MachineInstr *Const = this->MRI->getVRegDef(ConstReg);
732         assert(Const);
733         return (Const->getOpcode() == TargetOpcode::G_CONSTANT ||
734                 Const->getOpcode() == TargetOpcode::G_FCONSTANT);
735       }));
736 
737   auto MIB = BuildMI(*I.getParent(), I, I.getDebugLoc(),
738                      TII.get(SPIRV::OpConstantComposite))
739                  .addDef(ResVReg)
740                  .addUse(GR.getSPIRVTypeID(ResType));
741   for (unsigned i = I.getNumExplicitDefs(); i < I.getNumExplicitOperands(); ++i)
742     MIB.addUse(I.getOperand(i).getReg());
743   return MIB.constrainAllUses(TII, TRI, RBI);
744 }
745 
746 bool SPIRVInstructionSelector::selectCmp(Register ResVReg,
747                                          const SPIRVType *ResType,
748                                          unsigned CmpOpc,
749                                          MachineInstr &I) const {
750   Register Cmp0 = I.getOperand(2).getReg();
751   Register Cmp1 = I.getOperand(3).getReg();
752   assert(GR.getSPIRVTypeForVReg(Cmp0)->getOpcode() ==
753              GR.getSPIRVTypeForVReg(Cmp1)->getOpcode() &&
754          "CMP operands should have the same type");
755   return BuildMI(*I.getParent(), I, I.getDebugLoc(), TII.get(CmpOpc))
756       .addDef(ResVReg)
757       .addUse(GR.getSPIRVTypeID(ResType))
758       .addUse(Cmp0)
759       .addUse(Cmp1)
760       .constrainAllUses(TII, TRI, RBI);
761 }
762 
763 bool SPIRVInstructionSelector::selectICmp(Register ResVReg,
764                                           const SPIRVType *ResType,
765                                           MachineInstr &I) const {
766   auto Pred = I.getOperand(1).getPredicate();
767   unsigned CmpOpc;
768 
769   Register CmpOperand = I.getOperand(2).getReg();
770   if (GR.isScalarOfType(CmpOperand, SPIRV::OpTypePointer))
771     CmpOpc = getPtrCmpOpcode(Pred);
772   else if (GR.isScalarOrVectorOfType(CmpOperand, SPIRV::OpTypeBool))
773     CmpOpc = getBoolCmpOpcode(Pred);
774   else
775     CmpOpc = getICmpOpcode(Pred);
776   return selectCmp(ResVReg, ResType, CmpOpc, I);
777 }
778 
779 void SPIRVInstructionSelector::renderFImm32(MachineInstrBuilder &MIB,
780                                             const MachineInstr &I,
781                                             int OpIdx) const {
782   assert(I.getOpcode() == TargetOpcode::G_FCONSTANT && OpIdx == -1 &&
783          "Expected G_FCONSTANT");
784   const ConstantFP *FPImm = I.getOperand(1).getFPImm();
785   addNumImm(FPImm->getValueAPF().bitcastToAPInt(), MIB);
786 }
787 
788 void SPIRVInstructionSelector::renderImm32(MachineInstrBuilder &MIB,
789                                            const MachineInstr &I,
790                                            int OpIdx) const {
791   assert(I.getOpcode() == TargetOpcode::G_CONSTANT && OpIdx == -1 &&
792          "Expected G_CONSTANT");
793   addNumImm(I.getOperand(1).getCImm()->getValue(), MIB);
794 }
795 
796 Register
797 SPIRVInstructionSelector::buildI32Constant(uint32_t Val, MachineInstr &I,
798                                            const SPIRVType *ResType) const {
799   const SPIRVType *SpvI32Ty =
800       ResType ? ResType : GR.getOrCreateSPIRVIntegerType(32, I, TII);
801   Register NewReg;
802   NewReg = MRI->createGenericVirtualRegister(LLT::scalar(32));
803   MachineInstr *MI;
804   MachineBasicBlock &BB = *I.getParent();
805   if (Val == 0) {
806     MI = BuildMI(BB, I, I.getDebugLoc(), TII.get(SPIRV::OpConstantNull))
807              .addDef(NewReg)
808              .addUse(GR.getSPIRVTypeID(SpvI32Ty));
809   } else {
810     MI = BuildMI(BB, I, I.getDebugLoc(), TII.get(SPIRV::OpConstantI))
811              .addDef(NewReg)
812              .addUse(GR.getSPIRVTypeID(SpvI32Ty))
813              .addImm(APInt(32, Val).getZExtValue());
814   }
815   constrainSelectedInstRegOperands(*MI, TII, TRI, RBI);
816   return NewReg;
817 }
818 
819 bool SPIRVInstructionSelector::selectFCmp(Register ResVReg,
820                                           const SPIRVType *ResType,
821                                           MachineInstr &I) const {
822   unsigned CmpOp = getFCmpOpcode(I.getOperand(1).getPredicate());
823   return selectCmp(ResVReg, ResType, CmpOp, I);
824 }
825 
826 Register SPIRVInstructionSelector::buildZerosVal(const SPIRVType *ResType,
827                                                  MachineInstr &I) const {
828   return buildI32Constant(0, I, ResType);
829 }
830 
831 Register SPIRVInstructionSelector::buildOnesVal(bool AllOnes,
832                                                 const SPIRVType *ResType,
833                                                 MachineInstr &I) const {
834   unsigned BitWidth = GR.getScalarOrVectorBitWidth(ResType);
835   APInt One = AllOnes ? APInt::getAllOnesValue(BitWidth)
836                       : APInt::getOneBitSet(BitWidth, 0);
837   Register OneReg = buildI32Constant(One.getZExtValue(), I, ResType);
838   if (ResType->getOpcode() == SPIRV::OpTypeVector) {
839     const unsigned NumEles = ResType->getOperand(2).getImm();
840     Register OneVec = MRI->createVirtualRegister(&SPIRV::IDRegClass);
841     unsigned Opcode = SPIRV::OpConstantComposite;
842     auto MIB = BuildMI(*I.getParent(), I, I.getDebugLoc(), TII.get(Opcode))
843                    .addDef(OneVec)
844                    .addUse(GR.getSPIRVTypeID(ResType));
845     for (unsigned i = 0; i < NumEles; ++i)
846       MIB.addUse(OneReg);
847     constrainSelectedInstRegOperands(*MIB, TII, TRI, RBI);
848     return OneVec;
849   }
850   return OneReg;
851 }
852 
853 bool SPIRVInstructionSelector::selectSelect(Register ResVReg,
854                                             const SPIRVType *ResType,
855                                             MachineInstr &I,
856                                             bool IsSigned) const {
857   // To extend a bool, we need to use OpSelect between constants.
858   Register ZeroReg = buildZerosVal(ResType, I);
859   Register OneReg = buildOnesVal(IsSigned, ResType, I);
860   bool IsScalarBool =
861       GR.isScalarOfType(I.getOperand(1).getReg(), SPIRV::OpTypeBool);
862   unsigned Opcode =
863       IsScalarBool ? SPIRV::OpSelectSISCond : SPIRV::OpSelectSIVCond;
864   return BuildMI(*I.getParent(), I, I.getDebugLoc(), TII.get(Opcode))
865       .addDef(ResVReg)
866       .addUse(GR.getSPIRVTypeID(ResType))
867       .addUse(I.getOperand(1).getReg())
868       .addUse(OneReg)
869       .addUse(ZeroReg)
870       .constrainAllUses(TII, TRI, RBI);
871 }
872 
873 bool SPIRVInstructionSelector::selectIToF(Register ResVReg,
874                                           const SPIRVType *ResType,
875                                           MachineInstr &I, bool IsSigned,
876                                           unsigned Opcode) const {
877   Register SrcReg = I.getOperand(1).getReg();
878   // We can convert bool value directly to float type without OpConvert*ToF,
879   // however the translator generates OpSelect+OpConvert*ToF, so we do the same.
880   if (GR.isScalarOrVectorOfType(I.getOperand(1).getReg(), SPIRV::OpTypeBool)) {
881     unsigned BitWidth = GR.getScalarOrVectorBitWidth(ResType);
882     SPIRVType *TmpType = GR.getOrCreateSPIRVIntegerType(BitWidth, I, TII);
883     if (ResType->getOpcode() == SPIRV::OpTypeVector) {
884       const unsigned NumElts = ResType->getOperand(2).getImm();
885       TmpType = GR.getOrCreateSPIRVVectorType(TmpType, NumElts, I, TII);
886     }
887     SrcReg = MRI->createVirtualRegister(&SPIRV::IDRegClass);
888     selectSelect(SrcReg, TmpType, I, false);
889   }
890   return selectUnOpWithSrc(ResVReg, ResType, I, SrcReg, Opcode);
891 }
892 
893 bool SPIRVInstructionSelector::selectExt(Register ResVReg,
894                                          const SPIRVType *ResType,
895                                          MachineInstr &I, bool IsSigned) const {
896   if (GR.isScalarOrVectorOfType(I.getOperand(1).getReg(), SPIRV::OpTypeBool))
897     return selectSelect(ResVReg, ResType, I, IsSigned);
898   unsigned Opcode = IsSigned ? SPIRV::OpSConvert : SPIRV::OpUConvert;
899   return selectUnOp(ResVReg, ResType, I, Opcode);
900 }
901 
902 bool SPIRVInstructionSelector::selectIntToBool(Register IntReg,
903                                                Register ResVReg,
904                                                const SPIRVType *IntTy,
905                                                const SPIRVType *BoolTy,
906                                                MachineInstr &I) const {
907   // To truncate to a bool, we use OpBitwiseAnd 1 and OpINotEqual to zero.
908   Register BitIntReg = MRI->createVirtualRegister(&SPIRV::IDRegClass);
909   bool IsVectorTy = IntTy->getOpcode() == SPIRV::OpTypeVector;
910   unsigned Opcode = IsVectorTy ? SPIRV::OpBitwiseAndV : SPIRV::OpBitwiseAndS;
911   Register Zero = buildZerosVal(IntTy, I);
912   Register One = buildOnesVal(false, IntTy, I);
913   MachineBasicBlock &BB = *I.getParent();
914   BuildMI(BB, I, I.getDebugLoc(), TII.get(Opcode))
915       .addDef(BitIntReg)
916       .addUse(GR.getSPIRVTypeID(IntTy))
917       .addUse(IntReg)
918       .addUse(One)
919       .constrainAllUses(TII, TRI, RBI);
920   return BuildMI(BB, I, I.getDebugLoc(), TII.get(SPIRV::OpINotEqual))
921       .addDef(ResVReg)
922       .addUse(GR.getSPIRVTypeID(BoolTy))
923       .addUse(BitIntReg)
924       .addUse(Zero)
925       .constrainAllUses(TII, TRI, RBI);
926 }
927 
928 bool SPIRVInstructionSelector::selectTrunc(Register ResVReg,
929                                            const SPIRVType *ResType,
930                                            MachineInstr &I) const {
931   if (GR.isScalarOrVectorOfType(ResVReg, SPIRV::OpTypeBool)) {
932     Register IntReg = I.getOperand(1).getReg();
933     const SPIRVType *ArgType = GR.getSPIRVTypeForVReg(IntReg);
934     return selectIntToBool(IntReg, ResVReg, ArgType, ResType, I);
935   }
936   bool IsSigned = GR.isScalarOrVectorSigned(ResType);
937   unsigned Opcode = IsSigned ? SPIRV::OpSConvert : SPIRV::OpUConvert;
938   return selectUnOp(ResVReg, ResType, I, Opcode);
939 }
940 
941 bool SPIRVInstructionSelector::selectConst(Register ResVReg,
942                                            const SPIRVType *ResType,
943                                            const APInt &Imm,
944                                            MachineInstr &I) const {
945   assert(ResType->getOpcode() != SPIRV::OpTypePointer || Imm.isNullValue());
946   MachineBasicBlock &BB = *I.getParent();
947   if (ResType->getOpcode() == SPIRV::OpTypePointer && Imm.isNullValue()) {
948     return BuildMI(BB, I, I.getDebugLoc(), TII.get(SPIRV::OpConstantNull))
949         .addDef(ResVReg)
950         .addUse(GR.getSPIRVTypeID(ResType))
951         .constrainAllUses(TII, TRI, RBI);
952   }
953   auto MIB = BuildMI(BB, I, I.getDebugLoc(), TII.get(SPIRV::OpConstantI))
954                  .addDef(ResVReg)
955                  .addUse(GR.getSPIRVTypeID(ResType));
956   // <=32-bit integers should be caught by the sdag pattern.
957   assert(Imm.getBitWidth() > 32);
958   addNumImm(Imm, MIB);
959   return MIB.constrainAllUses(TII, TRI, RBI);
960 }
961 
962 bool SPIRVInstructionSelector::selectOpUndef(Register ResVReg,
963                                              const SPIRVType *ResType,
964                                              MachineInstr &I) const {
965   return BuildMI(*I.getParent(), I, I.getDebugLoc(), TII.get(SPIRV::OpUndef))
966       .addDef(ResVReg)
967       .addUse(GR.getSPIRVTypeID(ResType))
968       .constrainAllUses(TII, TRI, RBI);
969 }
970 
971 bool SPIRVInstructionSelector::selectIntrinsic(Register ResVReg,
972                                                const SPIRVType *ResType,
973                                                MachineInstr &I) const {
974   llvm_unreachable("Intrinsic selection not implemented");
975 }
976 
977 bool SPIRVInstructionSelector::selectFrameIndex(Register ResVReg,
978                                                 const SPIRVType *ResType,
979                                                 MachineInstr &I) const {
980   return BuildMI(*I.getParent(), I, I.getDebugLoc(), TII.get(SPIRV::OpVariable))
981       .addDef(ResVReg)
982       .addUse(GR.getSPIRVTypeID(ResType))
983       .addImm(static_cast<uint32_t>(SPIRV::StorageClass::Function))
984       .constrainAllUses(TII, TRI, RBI);
985 }
986 
987 bool SPIRVInstructionSelector::selectBranch(MachineInstr &I) const {
988   // InstructionSelector walks backwards through the instructions. We can use
989   // both a G_BR and a G_BRCOND to create an OpBranchConditional. We hit G_BR
990   // first, so can generate an OpBranchConditional here. If there is no
991   // G_BRCOND, we just use OpBranch for a regular unconditional branch.
992   const MachineInstr *PrevI = I.getPrevNode();
993   MachineBasicBlock &MBB = *I.getParent();
994   if (PrevI != nullptr && PrevI->getOpcode() == TargetOpcode::G_BRCOND) {
995     return BuildMI(MBB, I, I.getDebugLoc(), TII.get(SPIRV::OpBranchConditional))
996         .addUse(PrevI->getOperand(0).getReg())
997         .addMBB(PrevI->getOperand(1).getMBB())
998         .addMBB(I.getOperand(0).getMBB())
999         .constrainAllUses(TII, TRI, RBI);
1000   }
1001   return BuildMI(MBB, I, I.getDebugLoc(), TII.get(SPIRV::OpBranch))
1002       .addMBB(I.getOperand(0).getMBB())
1003       .constrainAllUses(TII, TRI, RBI);
1004 }
1005 
1006 bool SPIRVInstructionSelector::selectBranchCond(MachineInstr &I) const {
1007   // InstructionSelector walks backwards through the instructions. For an
1008   // explicit conditional branch with no fallthrough, we use both a G_BR and a
1009   // G_BRCOND to create an OpBranchConditional. We should hit G_BR first, and
1010   // generate the OpBranchConditional in selectBranch above.
1011   //
1012   // If an OpBranchConditional has been generated, we simply return, as the work
1013   // is alread done. If there is no OpBranchConditional, LLVM must be relying on
1014   // implicit fallthrough to the next basic block, so we need to create an
1015   // OpBranchConditional with an explicit "false" argument pointing to the next
1016   // basic block that LLVM would fall through to.
1017   const MachineInstr *NextI = I.getNextNode();
1018   // Check if this has already been successfully selected.
1019   if (NextI != nullptr && NextI->getOpcode() == SPIRV::OpBranchConditional)
1020     return true;
1021   // Must be relying on implicit block fallthrough, so generate an
1022   // OpBranchConditional with the "next" basic block as the "false" target.
1023   MachineBasicBlock &MBB = *I.getParent();
1024   unsigned NextMBBNum = MBB.getNextNode()->getNumber();
1025   MachineBasicBlock *NextMBB = I.getMF()->getBlockNumbered(NextMBBNum);
1026   return BuildMI(MBB, I, I.getDebugLoc(), TII.get(SPIRV::OpBranchConditional))
1027       .addUse(I.getOperand(0).getReg())
1028       .addMBB(I.getOperand(1).getMBB())
1029       .addMBB(NextMBB)
1030       .constrainAllUses(TII, TRI, RBI);
1031 }
1032 
1033 bool SPIRVInstructionSelector::selectPhi(Register ResVReg,
1034                                          const SPIRVType *ResType,
1035                                          MachineInstr &I) const {
1036   auto MIB = BuildMI(*I.getParent(), I, I.getDebugLoc(), TII.get(SPIRV::OpPhi))
1037                  .addDef(ResVReg)
1038                  .addUse(GR.getSPIRVTypeID(ResType));
1039   const unsigned NumOps = I.getNumOperands();
1040   for (unsigned i = 1; i < NumOps; i += 2) {
1041     MIB.addUse(I.getOperand(i + 0).getReg());
1042     MIB.addMBB(I.getOperand(i + 1).getMBB());
1043   }
1044   return MIB.constrainAllUses(TII, TRI, RBI);
1045 }
1046 
1047 bool SPIRVInstructionSelector::selectGlobalValue(
1048     Register ResVReg, MachineInstr &I, const MachineInstr *Init) const {
1049   // FIXME: don't use MachineIRBuilder here, replace it with BuildMI.
1050   MachineIRBuilder MIRBuilder(I);
1051   const GlobalValue *GV = I.getOperand(1).getGlobal();
1052   SPIRVType *ResType = GR.getOrCreateSPIRVType(
1053       GV->getType(), MIRBuilder, SPIRV::AccessQualifier::ReadWrite, false);
1054 
1055   std::string GlobalIdent = GV->getGlobalIdentifier();
1056   // TODO: suport @llvm.global.annotations.
1057   auto GlobalVar = cast<GlobalVariable>(GV);
1058 
1059   bool HasInit = GlobalVar->hasInitializer() &&
1060                  !isa<UndefValue>(GlobalVar->getInitializer());
1061   // Skip empty declaration for GVs with initilaizers till we get the decl with
1062   // passed initializer.
1063   if (HasInit && !Init)
1064     return true;
1065 
1066   unsigned AddrSpace = GV->getAddressSpace();
1067   SPIRV::StorageClass Storage = addressSpaceToStorageClass(AddrSpace);
1068   bool HasLnkTy = GV->getLinkage() != GlobalValue::InternalLinkage &&
1069                   Storage != SPIRV::StorageClass::Function;
1070   SPIRV::LinkageType LnkType =
1071       (GV->isDeclaration() || GV->hasAvailableExternallyLinkage())
1072           ? SPIRV::LinkageType::Import
1073           : SPIRV::LinkageType::Export;
1074 
1075   Register Reg = GR.buildGlobalVariable(ResVReg, ResType, GlobalIdent, GV,
1076                                         Storage, Init, GlobalVar->isConstant(),
1077                                         HasLnkTy, LnkType, MIRBuilder, true);
1078   return Reg.isValid();
1079 }
1080 
1081 namespace llvm {
1082 InstructionSelector *
1083 createSPIRVInstructionSelector(const SPIRVTargetMachine &TM,
1084                                const SPIRVSubtarget &Subtarget,
1085                                const RegisterBankInfo &RBI) {
1086   return new SPIRVInstructionSelector(TM, Subtarget, RBI);
1087 }
1088 } // namespace llvm
1089