1 //===-- llvm/CodeGen/GlobalISel/LegalizerHelper.cpp -----------------------===//
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 /// \file This file implements the LegalizerHelper class to legalize
10 /// individual instructions and the LegalizeMachineIR wrapper pass for the
11 /// primary legalization.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "llvm/CodeGen/GlobalISel/LegalizerHelper.h"
16 #include "llvm/CodeGen/GlobalISel/CallLowering.h"
17 #include "llvm/CodeGen/GlobalISel/GISelChangeObserver.h"
18 #include "llvm/CodeGen/GlobalISel/LegalizerInfo.h"
19 #include "llvm/CodeGen/MachineRegisterInfo.h"
20 #include "llvm/CodeGen/TargetFrameLowering.h"
21 #include "llvm/CodeGen/TargetInstrInfo.h"
22 #include "llvm/CodeGen/TargetLowering.h"
23 #include "llvm/CodeGen/TargetSubtargetInfo.h"
24 #include "llvm/Support/Debug.h"
25 #include "llvm/Support/MathExtras.h"
26 #include "llvm/Support/raw_ostream.h"
27 
28 #define DEBUG_TYPE "legalizer"
29 
30 using namespace llvm;
31 using namespace LegalizeActions;
32 
33 /// Try to break down \p OrigTy into \p NarrowTy sized pieces.
34 ///
35 /// Returns the number of \p NarrowTy elements needed to reconstruct \p OrigTy,
36 /// with any leftover piece as type \p LeftoverTy
37 ///
38 /// Returns -1 in the first element of the pair if the breakdown is not
39 /// satisfiable.
40 static std::pair<int, int>
41 getNarrowTypeBreakDown(LLT OrigTy, LLT NarrowTy, LLT &LeftoverTy) {
42   assert(!LeftoverTy.isValid() && "this is an out argument");
43 
44   unsigned Size = OrigTy.getSizeInBits();
45   unsigned NarrowSize = NarrowTy.getSizeInBits();
46   unsigned NumParts = Size / NarrowSize;
47   unsigned LeftoverSize = Size - NumParts * NarrowSize;
48   assert(Size > NarrowSize);
49 
50   if (LeftoverSize == 0)
51     return {NumParts, 0};
52 
53   if (NarrowTy.isVector()) {
54     unsigned EltSize = OrigTy.getScalarSizeInBits();
55     if (LeftoverSize % EltSize != 0)
56       return {-1, -1};
57     LeftoverTy = LLT::scalarOrVector(LeftoverSize / EltSize, EltSize);
58   } else {
59     LeftoverTy = LLT::scalar(LeftoverSize);
60   }
61 
62   int NumLeftover = LeftoverSize / LeftoverTy.getSizeInBits();
63   return std::make_pair(NumParts, NumLeftover);
64 }
65 
66 LegalizerHelper::LegalizerHelper(MachineFunction &MF,
67                                  GISelChangeObserver &Observer,
68                                  MachineIRBuilder &Builder)
69     : MIRBuilder(Builder), MRI(MF.getRegInfo()),
70       LI(*MF.getSubtarget().getLegalizerInfo()), Observer(Observer) {
71   MIRBuilder.setMF(MF);
72   MIRBuilder.setChangeObserver(Observer);
73 }
74 
75 LegalizerHelper::LegalizerHelper(MachineFunction &MF, const LegalizerInfo &LI,
76                                  GISelChangeObserver &Observer,
77                                  MachineIRBuilder &B)
78     : MIRBuilder(B), MRI(MF.getRegInfo()), LI(LI), Observer(Observer) {
79   MIRBuilder.setMF(MF);
80   MIRBuilder.setChangeObserver(Observer);
81 }
82 LegalizerHelper::LegalizeResult
83 LegalizerHelper::legalizeInstrStep(MachineInstr &MI) {
84   LLVM_DEBUG(dbgs() << "Legalizing: "; MI.print(dbgs()));
85 
86   if (MI.getOpcode() == TargetOpcode::G_INTRINSIC ||
87       MI.getOpcode() == TargetOpcode::G_INTRINSIC_W_SIDE_EFFECTS)
88     return LI.legalizeIntrinsic(MI, MRI, MIRBuilder) ? Legalized
89                                                      : UnableToLegalize;
90   auto Step = LI.getAction(MI, MRI);
91   switch (Step.Action) {
92   case Legal:
93     LLVM_DEBUG(dbgs() << ".. Already legal\n");
94     return AlreadyLegal;
95   case Libcall:
96     LLVM_DEBUG(dbgs() << ".. Convert to libcall\n");
97     return libcall(MI);
98   case NarrowScalar:
99     LLVM_DEBUG(dbgs() << ".. Narrow scalar\n");
100     return narrowScalar(MI, Step.TypeIdx, Step.NewType);
101   case WidenScalar:
102     LLVM_DEBUG(dbgs() << ".. Widen scalar\n");
103     return widenScalar(MI, Step.TypeIdx, Step.NewType);
104   case Lower:
105     LLVM_DEBUG(dbgs() << ".. Lower\n");
106     return lower(MI, Step.TypeIdx, Step.NewType);
107   case FewerElements:
108     LLVM_DEBUG(dbgs() << ".. Reduce number of elements\n");
109     return fewerElementsVector(MI, Step.TypeIdx, Step.NewType);
110   case MoreElements:
111     LLVM_DEBUG(dbgs() << ".. Increase number of elements\n");
112     return moreElementsVector(MI, Step.TypeIdx, Step.NewType);
113   case Custom:
114     LLVM_DEBUG(dbgs() << ".. Custom legalization\n");
115     return LI.legalizeCustom(MI, MRI, MIRBuilder, Observer) ? Legalized
116                                                             : UnableToLegalize;
117   default:
118     LLVM_DEBUG(dbgs() << ".. Unable to legalize\n");
119     return UnableToLegalize;
120   }
121 }
122 
123 void LegalizerHelper::extractParts(Register Reg, LLT Ty, int NumParts,
124                                    SmallVectorImpl<Register> &VRegs) {
125   for (int i = 0; i < NumParts; ++i)
126     VRegs.push_back(MRI.createGenericVirtualRegister(Ty));
127   MIRBuilder.buildUnmerge(VRegs, Reg);
128 }
129 
130 bool LegalizerHelper::extractParts(Register Reg, LLT RegTy,
131                                    LLT MainTy, LLT &LeftoverTy,
132                                    SmallVectorImpl<Register> &VRegs,
133                                    SmallVectorImpl<Register> &LeftoverRegs) {
134   assert(!LeftoverTy.isValid() && "this is an out argument");
135 
136   unsigned RegSize = RegTy.getSizeInBits();
137   unsigned MainSize = MainTy.getSizeInBits();
138   unsigned NumParts = RegSize / MainSize;
139   unsigned LeftoverSize = RegSize - NumParts * MainSize;
140 
141   // Use an unmerge when possible.
142   if (LeftoverSize == 0) {
143     for (unsigned I = 0; I < NumParts; ++I)
144       VRegs.push_back(MRI.createGenericVirtualRegister(MainTy));
145     MIRBuilder.buildUnmerge(VRegs, Reg);
146     return true;
147   }
148 
149   if (MainTy.isVector()) {
150     unsigned EltSize = MainTy.getScalarSizeInBits();
151     if (LeftoverSize % EltSize != 0)
152       return false;
153     LeftoverTy = LLT::scalarOrVector(LeftoverSize / EltSize, EltSize);
154   } else {
155     LeftoverTy = LLT::scalar(LeftoverSize);
156   }
157 
158   // For irregular sizes, extract the individual parts.
159   for (unsigned I = 0; I != NumParts; ++I) {
160     Register NewReg = MRI.createGenericVirtualRegister(MainTy);
161     VRegs.push_back(NewReg);
162     MIRBuilder.buildExtract(NewReg, Reg, MainSize * I);
163   }
164 
165   for (unsigned Offset = MainSize * NumParts; Offset < RegSize;
166        Offset += LeftoverSize) {
167     Register NewReg = MRI.createGenericVirtualRegister(LeftoverTy);
168     LeftoverRegs.push_back(NewReg);
169     MIRBuilder.buildExtract(NewReg, Reg, Offset);
170   }
171 
172   return true;
173 }
174 
175 static LLT getGCDType(LLT OrigTy, LLT TargetTy) {
176   if (OrigTy.isVector() && TargetTy.isVector()) {
177     assert(OrigTy.getElementType() == TargetTy.getElementType());
178     int GCD = greatestCommonDivisor(OrigTy.getNumElements(),
179                                     TargetTy.getNumElements());
180     return LLT::scalarOrVector(GCD, OrigTy.getElementType());
181   }
182 
183   if (OrigTy.isVector() && !TargetTy.isVector()) {
184     assert(OrigTy.getElementType() == TargetTy);
185     return TargetTy;
186   }
187 
188   assert(!OrigTy.isVector() && !TargetTy.isVector());
189 
190   int GCD = greatestCommonDivisor(OrigTy.getSizeInBits(),
191                                   TargetTy.getSizeInBits());
192   return LLT::scalar(GCD);
193 }
194 
195 void LegalizerHelper::insertParts(Register DstReg,
196                                   LLT ResultTy, LLT PartTy,
197                                   ArrayRef<Register> PartRegs,
198                                   LLT LeftoverTy,
199                                   ArrayRef<Register> LeftoverRegs) {
200   if (!LeftoverTy.isValid()) {
201     assert(LeftoverRegs.empty());
202 
203     if (!ResultTy.isVector()) {
204       MIRBuilder.buildMerge(DstReg, PartRegs);
205       return;
206     }
207 
208     if (PartTy.isVector())
209       MIRBuilder.buildConcatVectors(DstReg, PartRegs);
210     else
211       MIRBuilder.buildBuildVector(DstReg, PartRegs);
212     return;
213   }
214 
215   unsigned PartSize = PartTy.getSizeInBits();
216   unsigned LeftoverPartSize = LeftoverTy.getSizeInBits();
217 
218   Register CurResultReg = MRI.createGenericVirtualRegister(ResultTy);
219   MIRBuilder.buildUndef(CurResultReg);
220 
221   unsigned Offset = 0;
222   for (Register PartReg : PartRegs) {
223     Register NewResultReg = MRI.createGenericVirtualRegister(ResultTy);
224     MIRBuilder.buildInsert(NewResultReg, CurResultReg, PartReg, Offset);
225     CurResultReg = NewResultReg;
226     Offset += PartSize;
227   }
228 
229   for (unsigned I = 0, E = LeftoverRegs.size(); I != E; ++I) {
230     // Use the original output register for the final insert to avoid a copy.
231     Register NewResultReg = (I + 1 == E) ?
232       DstReg : MRI.createGenericVirtualRegister(ResultTy);
233 
234     MIRBuilder.buildInsert(NewResultReg, CurResultReg, LeftoverRegs[I], Offset);
235     CurResultReg = NewResultReg;
236     Offset += LeftoverPartSize;
237   }
238 }
239 
240 static RTLIB::Libcall getRTLibDesc(unsigned Opcode, unsigned Size) {
241   switch (Opcode) {
242   case TargetOpcode::G_SDIV:
243     assert((Size == 32 || Size == 64 || Size == 128) && "Unsupported size");
244     switch (Size) {
245     case 32:
246       return RTLIB::SDIV_I32;
247     case 64:
248       return RTLIB::SDIV_I64;
249     case 128:
250       return RTLIB::SDIV_I128;
251     default:
252       llvm_unreachable("unexpected size");
253     }
254   case TargetOpcode::G_UDIV:
255     assert((Size == 32 || Size == 64 || Size == 128) && "Unsupported size");
256     switch (Size) {
257     case 32:
258       return RTLIB::UDIV_I32;
259     case 64:
260       return RTLIB::UDIV_I64;
261     case 128:
262       return RTLIB::UDIV_I128;
263     default:
264       llvm_unreachable("unexpected size");
265     }
266   case TargetOpcode::G_SREM:
267     assert((Size == 32 || Size == 64) && "Unsupported size");
268     return Size == 64 ? RTLIB::SREM_I64 : RTLIB::SREM_I32;
269   case TargetOpcode::G_UREM:
270     assert((Size == 32 || Size == 64) && "Unsupported size");
271     return Size == 64 ? RTLIB::UREM_I64 : RTLIB::UREM_I32;
272   case TargetOpcode::G_CTLZ_ZERO_UNDEF:
273     assert(Size == 32 && "Unsupported size");
274     return RTLIB::CTLZ_I32;
275   case TargetOpcode::G_FADD:
276     assert((Size == 32 || Size == 64) && "Unsupported size");
277     return Size == 64 ? RTLIB::ADD_F64 : RTLIB::ADD_F32;
278   case TargetOpcode::G_FSUB:
279     assert((Size == 32 || Size == 64) && "Unsupported size");
280     return Size == 64 ? RTLIB::SUB_F64 : RTLIB::SUB_F32;
281   case TargetOpcode::G_FMUL:
282     assert((Size == 32 || Size == 64) && "Unsupported size");
283     return Size == 64 ? RTLIB::MUL_F64 : RTLIB::MUL_F32;
284   case TargetOpcode::G_FDIV:
285     assert((Size == 32 || Size == 64) && "Unsupported size");
286     return Size == 64 ? RTLIB::DIV_F64 : RTLIB::DIV_F32;
287   case TargetOpcode::G_FEXP:
288     assert((Size == 32 || Size == 64) && "Unsupported size");
289     return Size == 64 ? RTLIB::EXP_F64 : RTLIB::EXP_F32;
290   case TargetOpcode::G_FEXP2:
291     assert((Size == 32 || Size == 64) && "Unsupported size");
292     return Size == 64 ? RTLIB::EXP2_F64 : RTLIB::EXP2_F32;
293   case TargetOpcode::G_FREM:
294     return Size == 64 ? RTLIB::REM_F64 : RTLIB::REM_F32;
295   case TargetOpcode::G_FPOW:
296     return Size == 64 ? RTLIB::POW_F64 : RTLIB::POW_F32;
297   case TargetOpcode::G_FMA:
298     assert((Size == 32 || Size == 64) && "Unsupported size");
299     return Size == 64 ? RTLIB::FMA_F64 : RTLIB::FMA_F32;
300   case TargetOpcode::G_FSIN:
301     assert((Size == 32 || Size == 64 || Size == 128) && "Unsupported size");
302     return Size == 128 ? RTLIB::SIN_F128
303                        : Size == 64 ? RTLIB::SIN_F64 : RTLIB::SIN_F32;
304   case TargetOpcode::G_FCOS:
305     assert((Size == 32 || Size == 64 || Size == 128) && "Unsupported size");
306     return Size == 128 ? RTLIB::COS_F128
307                        : Size == 64 ? RTLIB::COS_F64 : RTLIB::COS_F32;
308   case TargetOpcode::G_FLOG10:
309     assert((Size == 32 || Size == 64 || Size == 128) && "Unsupported size");
310     return Size == 128 ? RTLIB::LOG10_F128
311                        : Size == 64 ? RTLIB::LOG10_F64 : RTLIB::LOG10_F32;
312   case TargetOpcode::G_FLOG:
313     assert((Size == 32 || Size == 64 || Size == 128) && "Unsupported size");
314     return Size == 128 ? RTLIB::LOG_F128
315                        : Size == 64 ? RTLIB::LOG_F64 : RTLIB::LOG_F32;
316   case TargetOpcode::G_FLOG2:
317     assert((Size == 32 || Size == 64 || Size == 128) && "Unsupported size");
318     return Size == 128 ? RTLIB::LOG2_F128
319                        : Size == 64 ? RTLIB::LOG2_F64 : RTLIB::LOG2_F32;
320   case TargetOpcode::G_FCEIL:
321     assert((Size == 32 || Size == 64) && "Unsupported size");
322     return Size == 64 ? RTLIB::CEIL_F64 : RTLIB::CEIL_F32;
323   case TargetOpcode::G_FFLOOR:
324     assert((Size == 32 || Size == 64) && "Unsupported size");
325     return Size == 64 ? RTLIB::FLOOR_F64 : RTLIB::FLOOR_F32;
326   }
327   llvm_unreachable("Unknown libcall function");
328 }
329 
330 /// True if an instruction is in tail position in its caller. Intended for
331 /// legalizing libcalls as tail calls when possible.
332 static bool isLibCallInTailPosition(MachineInstr &MI) {
333   const Function &F = MI.getParent()->getParent()->getFunction();
334 
335   // Conservatively require the attributes of the call to match those of
336   // the return. Ignore NoAlias and NonNull because they don't affect the
337   // call sequence.
338   AttributeList CallerAttrs = F.getAttributes();
339   if (AttrBuilder(CallerAttrs, AttributeList::ReturnIndex)
340           .removeAttribute(Attribute::NoAlias)
341           .removeAttribute(Attribute::NonNull)
342           .hasAttributes())
343     return false;
344 
345   // It's not safe to eliminate the sign / zero extension of the return value.
346   if (CallerAttrs.hasAttribute(AttributeList::ReturnIndex, Attribute::ZExt) ||
347       CallerAttrs.hasAttribute(AttributeList::ReturnIndex, Attribute::SExt))
348     return false;
349 
350   // Only tail call if the following instruction is a standard return.
351   auto &TII = *MI.getMF()->getSubtarget().getInstrInfo();
352   MachineInstr *Next = MI.getNextNode();
353   if (!Next || TII.isTailCall(*Next) || !Next->isReturn())
354     return false;
355 
356   return true;
357 }
358 
359 LegalizerHelper::LegalizeResult
360 llvm::createLibcall(MachineIRBuilder &MIRBuilder, RTLIB::Libcall Libcall,
361                     const CallLowering::ArgInfo &Result,
362                     ArrayRef<CallLowering::ArgInfo> Args) {
363   auto &CLI = *MIRBuilder.getMF().getSubtarget().getCallLowering();
364   auto &TLI = *MIRBuilder.getMF().getSubtarget().getTargetLowering();
365   const char *Name = TLI.getLibcallName(Libcall);
366 
367   CallLowering::CallLoweringInfo Info;
368   Info.CallConv = TLI.getLibcallCallingConv(Libcall);
369   Info.Callee = MachineOperand::CreateES(Name);
370   Info.OrigRet = Result;
371   std::copy(Args.begin(), Args.end(), std::back_inserter(Info.OrigArgs));
372   if (!CLI.lowerCall(MIRBuilder, Info))
373     return LegalizerHelper::UnableToLegalize;
374 
375   return LegalizerHelper::Legalized;
376 }
377 
378 // Useful for libcalls where all operands have the same type.
379 static LegalizerHelper::LegalizeResult
380 simpleLibcall(MachineInstr &MI, MachineIRBuilder &MIRBuilder, unsigned Size,
381               Type *OpType) {
382   auto Libcall = getRTLibDesc(MI.getOpcode(), Size);
383 
384   SmallVector<CallLowering::ArgInfo, 3> Args;
385   for (unsigned i = 1; i < MI.getNumOperands(); i++)
386     Args.push_back({MI.getOperand(i).getReg(), OpType});
387   return createLibcall(MIRBuilder, Libcall, {MI.getOperand(0).getReg(), OpType},
388                        Args);
389 }
390 
391 LegalizerHelper::LegalizeResult
392 llvm::createMemLibcall(MachineIRBuilder &MIRBuilder, MachineRegisterInfo &MRI,
393                        MachineInstr &MI) {
394   assert(MI.getOpcode() == TargetOpcode::G_INTRINSIC_W_SIDE_EFFECTS);
395   auto &Ctx = MIRBuilder.getMF().getFunction().getContext();
396 
397   SmallVector<CallLowering::ArgInfo, 3> Args;
398   for (unsigned i = 1; i < MI.getNumOperands(); i++) {
399     Register Reg = MI.getOperand(i).getReg();
400 
401     // Need derive an IR type for call lowering.
402     LLT OpLLT = MRI.getType(Reg);
403     Type *OpTy = nullptr;
404     if (OpLLT.isPointer())
405       OpTy = Type::getInt8PtrTy(Ctx, OpLLT.getAddressSpace());
406     else
407       OpTy = IntegerType::get(Ctx, OpLLT.getSizeInBits());
408     Args.push_back({Reg, OpTy});
409   }
410 
411   auto &CLI = *MIRBuilder.getMF().getSubtarget().getCallLowering();
412   auto &TLI = *MIRBuilder.getMF().getSubtarget().getTargetLowering();
413   Intrinsic::ID ID = MI.getOperand(0).getIntrinsicID();
414   RTLIB::Libcall RTLibcall;
415   switch (ID) {
416   case Intrinsic::memcpy:
417     RTLibcall = RTLIB::MEMCPY;
418     break;
419   case Intrinsic::memset:
420     RTLibcall = RTLIB::MEMSET;
421     break;
422   case Intrinsic::memmove:
423     RTLibcall = RTLIB::MEMMOVE;
424     break;
425   default:
426     return LegalizerHelper::UnableToLegalize;
427   }
428   const char *Name = TLI.getLibcallName(RTLibcall);
429 
430   MIRBuilder.setInstr(MI);
431 
432   CallLowering::CallLoweringInfo Info;
433   Info.CallConv = TLI.getLibcallCallingConv(RTLibcall);
434   Info.Callee = MachineOperand::CreateES(Name);
435   Info.OrigRet = CallLowering::ArgInfo({0}, Type::getVoidTy(Ctx));
436   Info.IsTailCall = isLibCallInTailPosition(MI);
437 
438   std::copy(Args.begin(), Args.end(), std::back_inserter(Info.OrigArgs));
439   if (!CLI.lowerCall(MIRBuilder, Info))
440     return LegalizerHelper::UnableToLegalize;
441 
442   if (Info.LoweredTailCall) {
443     assert(Info.IsTailCall && "Lowered tail call when it wasn't a tail call?");
444     // We must have a return following the call to get past
445     // isLibCallInTailPosition.
446     assert(MI.getNextNode() && MI.getNextNode()->isReturn() &&
447            "Expected instr following MI to be a return?");
448 
449     // We lowered a tail call, so the call is now the return from the block.
450     // Delete the old return.
451     MI.getNextNode()->eraseFromParent();
452   }
453 
454   return LegalizerHelper::Legalized;
455 }
456 
457 static RTLIB::Libcall getConvRTLibDesc(unsigned Opcode, Type *ToType,
458                                        Type *FromType) {
459   auto ToMVT = MVT::getVT(ToType);
460   auto FromMVT = MVT::getVT(FromType);
461 
462   switch (Opcode) {
463   case TargetOpcode::G_FPEXT:
464     return RTLIB::getFPEXT(FromMVT, ToMVT);
465   case TargetOpcode::G_FPTRUNC:
466     return RTLIB::getFPROUND(FromMVT, ToMVT);
467   case TargetOpcode::G_FPTOSI:
468     return RTLIB::getFPTOSINT(FromMVT, ToMVT);
469   case TargetOpcode::G_FPTOUI:
470     return RTLIB::getFPTOUINT(FromMVT, ToMVT);
471   case TargetOpcode::G_SITOFP:
472     return RTLIB::getSINTTOFP(FromMVT, ToMVT);
473   case TargetOpcode::G_UITOFP:
474     return RTLIB::getUINTTOFP(FromMVT, ToMVT);
475   }
476   llvm_unreachable("Unsupported libcall function");
477 }
478 
479 static LegalizerHelper::LegalizeResult
480 conversionLibcall(MachineInstr &MI, MachineIRBuilder &MIRBuilder, Type *ToType,
481                   Type *FromType) {
482   RTLIB::Libcall Libcall = getConvRTLibDesc(MI.getOpcode(), ToType, FromType);
483   return createLibcall(MIRBuilder, Libcall, {MI.getOperand(0).getReg(), ToType},
484                        {{MI.getOperand(1).getReg(), FromType}});
485 }
486 
487 LegalizerHelper::LegalizeResult
488 LegalizerHelper::libcall(MachineInstr &MI) {
489   LLT LLTy = MRI.getType(MI.getOperand(0).getReg());
490   unsigned Size = LLTy.getSizeInBits();
491   auto &Ctx = MIRBuilder.getMF().getFunction().getContext();
492 
493   MIRBuilder.setInstr(MI);
494 
495   switch (MI.getOpcode()) {
496   default:
497     return UnableToLegalize;
498   case TargetOpcode::G_SDIV:
499   case TargetOpcode::G_UDIV:
500   case TargetOpcode::G_SREM:
501   case TargetOpcode::G_UREM:
502   case TargetOpcode::G_CTLZ_ZERO_UNDEF: {
503     Type *HLTy = IntegerType::get(Ctx, Size);
504     auto Status = simpleLibcall(MI, MIRBuilder, Size, HLTy);
505     if (Status != Legalized)
506       return Status;
507     break;
508   }
509   case TargetOpcode::G_FADD:
510   case TargetOpcode::G_FSUB:
511   case TargetOpcode::G_FMUL:
512   case TargetOpcode::G_FDIV:
513   case TargetOpcode::G_FMA:
514   case TargetOpcode::G_FPOW:
515   case TargetOpcode::G_FREM:
516   case TargetOpcode::G_FCOS:
517   case TargetOpcode::G_FSIN:
518   case TargetOpcode::G_FLOG10:
519   case TargetOpcode::G_FLOG:
520   case TargetOpcode::G_FLOG2:
521   case TargetOpcode::G_FEXP:
522   case TargetOpcode::G_FEXP2:
523   case TargetOpcode::G_FCEIL:
524   case TargetOpcode::G_FFLOOR: {
525     if (Size > 64) {
526       LLVM_DEBUG(dbgs() << "Size " << Size << " too large to legalize.\n");
527       return UnableToLegalize;
528     }
529     Type *HLTy = Size == 64 ? Type::getDoubleTy(Ctx) : Type::getFloatTy(Ctx);
530     auto Status = simpleLibcall(MI, MIRBuilder, Size, HLTy);
531     if (Status != Legalized)
532       return Status;
533     break;
534   }
535   case TargetOpcode::G_FPEXT: {
536     // FIXME: Support other floating point types (half, fp128 etc)
537     unsigned FromSize = MRI.getType(MI.getOperand(1).getReg()).getSizeInBits();
538     unsigned ToSize = MRI.getType(MI.getOperand(0).getReg()).getSizeInBits();
539     if (ToSize != 64 || FromSize != 32)
540       return UnableToLegalize;
541     LegalizeResult Status = conversionLibcall(
542         MI, MIRBuilder, Type::getDoubleTy(Ctx), Type::getFloatTy(Ctx));
543     if (Status != Legalized)
544       return Status;
545     break;
546   }
547   case TargetOpcode::G_FPTRUNC: {
548     // FIXME: Support other floating point types (half, fp128 etc)
549     unsigned FromSize = MRI.getType(MI.getOperand(1).getReg()).getSizeInBits();
550     unsigned ToSize = MRI.getType(MI.getOperand(0).getReg()).getSizeInBits();
551     if (ToSize != 32 || FromSize != 64)
552       return UnableToLegalize;
553     LegalizeResult Status = conversionLibcall(
554         MI, MIRBuilder, Type::getFloatTy(Ctx), Type::getDoubleTy(Ctx));
555     if (Status != Legalized)
556       return Status;
557     break;
558   }
559   case TargetOpcode::G_FPTOSI:
560   case TargetOpcode::G_FPTOUI: {
561     // FIXME: Support other types
562     unsigned FromSize = MRI.getType(MI.getOperand(1).getReg()).getSizeInBits();
563     unsigned ToSize = MRI.getType(MI.getOperand(0).getReg()).getSizeInBits();
564     if ((ToSize != 32 && ToSize != 64) || (FromSize != 32 && FromSize != 64))
565       return UnableToLegalize;
566     LegalizeResult Status = conversionLibcall(
567         MI, MIRBuilder,
568         ToSize == 32 ? Type::getInt32Ty(Ctx) : Type::getInt64Ty(Ctx),
569         FromSize == 64 ? Type::getDoubleTy(Ctx) : Type::getFloatTy(Ctx));
570     if (Status != Legalized)
571       return Status;
572     break;
573   }
574   case TargetOpcode::G_SITOFP:
575   case TargetOpcode::G_UITOFP: {
576     // FIXME: Support other types
577     unsigned FromSize = MRI.getType(MI.getOperand(1).getReg()).getSizeInBits();
578     unsigned ToSize = MRI.getType(MI.getOperand(0).getReg()).getSizeInBits();
579     if ((FromSize != 32 && FromSize != 64) || (ToSize != 32 && ToSize != 64))
580       return UnableToLegalize;
581     LegalizeResult Status = conversionLibcall(
582         MI, MIRBuilder,
583         ToSize == 64 ? Type::getDoubleTy(Ctx) : Type::getFloatTy(Ctx),
584         FromSize == 32 ? Type::getInt32Ty(Ctx) : Type::getInt64Ty(Ctx));
585     if (Status != Legalized)
586       return Status;
587     break;
588   }
589   }
590 
591   MI.eraseFromParent();
592   return Legalized;
593 }
594 
595 LegalizerHelper::LegalizeResult LegalizerHelper::narrowScalar(MachineInstr &MI,
596                                                               unsigned TypeIdx,
597                                                               LLT NarrowTy) {
598   MIRBuilder.setInstr(MI);
599 
600   uint64_t SizeOp0 = MRI.getType(MI.getOperand(0).getReg()).getSizeInBits();
601   uint64_t NarrowSize = NarrowTy.getSizeInBits();
602 
603   switch (MI.getOpcode()) {
604   default:
605     return UnableToLegalize;
606   case TargetOpcode::G_IMPLICIT_DEF: {
607     // FIXME: add support for when SizeOp0 isn't an exact multiple of
608     // NarrowSize.
609     if (SizeOp0 % NarrowSize != 0)
610       return UnableToLegalize;
611     int NumParts = SizeOp0 / NarrowSize;
612 
613     SmallVector<Register, 2> DstRegs;
614     for (int i = 0; i < NumParts; ++i)
615       DstRegs.push_back(
616           MIRBuilder.buildUndef(NarrowTy)->getOperand(0).getReg());
617 
618     Register DstReg = MI.getOperand(0).getReg();
619     if(MRI.getType(DstReg).isVector())
620       MIRBuilder.buildBuildVector(DstReg, DstRegs);
621     else
622       MIRBuilder.buildMerge(DstReg, DstRegs);
623     MI.eraseFromParent();
624     return Legalized;
625   }
626   case TargetOpcode::G_CONSTANT: {
627     LLT Ty = MRI.getType(MI.getOperand(0).getReg());
628     const APInt &Val = MI.getOperand(1).getCImm()->getValue();
629     unsigned TotalSize = Ty.getSizeInBits();
630     unsigned NarrowSize = NarrowTy.getSizeInBits();
631     int NumParts = TotalSize / NarrowSize;
632 
633     SmallVector<Register, 4> PartRegs;
634     for (int I = 0; I != NumParts; ++I) {
635       unsigned Offset = I * NarrowSize;
636       auto K = MIRBuilder.buildConstant(NarrowTy,
637                                         Val.lshr(Offset).trunc(NarrowSize));
638       PartRegs.push_back(K.getReg(0));
639     }
640 
641     LLT LeftoverTy;
642     unsigned LeftoverBits = TotalSize - NumParts * NarrowSize;
643     SmallVector<Register, 1> LeftoverRegs;
644     if (LeftoverBits != 0) {
645       LeftoverTy = LLT::scalar(LeftoverBits);
646       auto K = MIRBuilder.buildConstant(
647         LeftoverTy,
648         Val.lshr(NumParts * NarrowSize).trunc(LeftoverBits));
649       LeftoverRegs.push_back(K.getReg(0));
650     }
651 
652     insertParts(MI.getOperand(0).getReg(),
653                 Ty, NarrowTy, PartRegs, LeftoverTy, LeftoverRegs);
654 
655     MI.eraseFromParent();
656     return Legalized;
657   }
658   case TargetOpcode::G_SEXT: {
659     if (TypeIdx != 0)
660       return UnableToLegalize;
661 
662     Register SrcReg = MI.getOperand(1).getReg();
663     LLT SrcTy = MRI.getType(SrcReg);
664 
665     // FIXME: support the general case where the requested NarrowTy may not be
666     // the same as the source type. E.g. s128 = sext(s32)
667     if ((SrcTy.getSizeInBits() != SizeOp0 / 2) ||
668         SrcTy.getSizeInBits() != NarrowTy.getSizeInBits()) {
669       LLVM_DEBUG(dbgs() << "Can't narrow sext to type " << NarrowTy << "\n");
670       return UnableToLegalize;
671     }
672 
673     // Shift the sign bit of the low register through the high register.
674     auto ShiftAmt =
675         MIRBuilder.buildConstant(LLT::scalar(64), NarrowTy.getSizeInBits() - 1);
676     auto Shift = MIRBuilder.buildAShr(NarrowTy, SrcReg, ShiftAmt);
677     MIRBuilder.buildMerge(MI.getOperand(0).getReg(), {SrcReg, Shift.getReg(0)});
678     MI.eraseFromParent();
679     return Legalized;
680   }
681   case TargetOpcode::G_ZEXT: {
682     if (TypeIdx != 0)
683       return UnableToLegalize;
684 
685     LLT SrcTy = MRI.getType(MI.getOperand(1).getReg());
686     uint64_t SizeOp1 = SrcTy.getSizeInBits();
687     if (SizeOp0 % SizeOp1 != 0)
688       return UnableToLegalize;
689 
690     // Generate a merge where the bottom bits are taken from the source, and
691     // zero everything else.
692     Register ZeroReg = MIRBuilder.buildConstant(SrcTy, 0).getReg(0);
693     unsigned NumParts = SizeOp0 / SizeOp1;
694     SmallVector<Register, 4> Srcs = {MI.getOperand(1).getReg()};
695     for (unsigned Part = 1; Part < NumParts; ++Part)
696       Srcs.push_back(ZeroReg);
697     MIRBuilder.buildMerge(MI.getOperand(0).getReg(), Srcs);
698     MI.eraseFromParent();
699     return Legalized;
700   }
701   case TargetOpcode::G_TRUNC: {
702     if (TypeIdx != 1)
703       return UnableToLegalize;
704 
705     uint64_t SizeOp1 = MRI.getType(MI.getOperand(1).getReg()).getSizeInBits();
706     if (NarrowTy.getSizeInBits() * 2 != SizeOp1) {
707       LLVM_DEBUG(dbgs() << "Can't narrow trunc to type " << NarrowTy << "\n");
708       return UnableToLegalize;
709     }
710 
711     auto Unmerge = MIRBuilder.buildUnmerge(NarrowTy, MI.getOperand(1).getReg());
712     MIRBuilder.buildCopy(MI.getOperand(0).getReg(), Unmerge.getReg(0));
713     MI.eraseFromParent();
714     return Legalized;
715   }
716 
717   case TargetOpcode::G_ADD: {
718     // FIXME: add support for when SizeOp0 isn't an exact multiple of
719     // NarrowSize.
720     if (SizeOp0 % NarrowSize != 0)
721       return UnableToLegalize;
722     // Expand in terms of carry-setting/consuming G_ADDE instructions.
723     int NumParts = SizeOp0 / NarrowTy.getSizeInBits();
724 
725     SmallVector<Register, 2> Src1Regs, Src2Regs, DstRegs;
726     extractParts(MI.getOperand(1).getReg(), NarrowTy, NumParts, Src1Regs);
727     extractParts(MI.getOperand(2).getReg(), NarrowTy, NumParts, Src2Regs);
728 
729     Register CarryIn;
730     for (int i = 0; i < NumParts; ++i) {
731       Register DstReg = MRI.createGenericVirtualRegister(NarrowTy);
732       Register CarryOut = MRI.createGenericVirtualRegister(LLT::scalar(1));
733 
734       if (i == 0)
735         MIRBuilder.buildUAddo(DstReg, CarryOut, Src1Regs[i], Src2Regs[i]);
736       else {
737         MIRBuilder.buildUAdde(DstReg, CarryOut, Src1Regs[i],
738                               Src2Regs[i], CarryIn);
739       }
740 
741       DstRegs.push_back(DstReg);
742       CarryIn = CarryOut;
743     }
744     Register DstReg = MI.getOperand(0).getReg();
745     if(MRI.getType(DstReg).isVector())
746       MIRBuilder.buildBuildVector(DstReg, DstRegs);
747     else
748       MIRBuilder.buildMerge(DstReg, DstRegs);
749     MI.eraseFromParent();
750     return Legalized;
751   }
752   case TargetOpcode::G_SUB: {
753     // FIXME: add support for when SizeOp0 isn't an exact multiple of
754     // NarrowSize.
755     if (SizeOp0 % NarrowSize != 0)
756       return UnableToLegalize;
757 
758     int NumParts = SizeOp0 / NarrowTy.getSizeInBits();
759 
760     SmallVector<Register, 2> Src1Regs, Src2Regs, DstRegs;
761     extractParts(MI.getOperand(1).getReg(), NarrowTy, NumParts, Src1Regs);
762     extractParts(MI.getOperand(2).getReg(), NarrowTy, NumParts, Src2Regs);
763 
764     Register DstReg = MRI.createGenericVirtualRegister(NarrowTy);
765     Register BorrowOut = MRI.createGenericVirtualRegister(LLT::scalar(1));
766     MIRBuilder.buildInstr(TargetOpcode::G_USUBO, {DstReg, BorrowOut},
767                           {Src1Regs[0], Src2Regs[0]});
768     DstRegs.push_back(DstReg);
769     Register BorrowIn = BorrowOut;
770     for (int i = 1; i < NumParts; ++i) {
771       DstReg = MRI.createGenericVirtualRegister(NarrowTy);
772       BorrowOut = MRI.createGenericVirtualRegister(LLT::scalar(1));
773 
774       MIRBuilder.buildInstr(TargetOpcode::G_USUBE, {DstReg, BorrowOut},
775                             {Src1Regs[i], Src2Regs[i], BorrowIn});
776 
777       DstRegs.push_back(DstReg);
778       BorrowIn = BorrowOut;
779     }
780     MIRBuilder.buildMerge(MI.getOperand(0).getReg(), DstRegs);
781     MI.eraseFromParent();
782     return Legalized;
783   }
784   case TargetOpcode::G_MUL:
785   case TargetOpcode::G_UMULH:
786     return narrowScalarMul(MI, NarrowTy);
787   case TargetOpcode::G_EXTRACT:
788     return narrowScalarExtract(MI, TypeIdx, NarrowTy);
789   case TargetOpcode::G_INSERT:
790     return narrowScalarInsert(MI, TypeIdx, NarrowTy);
791   case TargetOpcode::G_LOAD: {
792     const auto &MMO = **MI.memoperands_begin();
793     Register DstReg = MI.getOperand(0).getReg();
794     LLT DstTy = MRI.getType(DstReg);
795     if (DstTy.isVector())
796       return UnableToLegalize;
797 
798     if (8 * MMO.getSize() != DstTy.getSizeInBits()) {
799       Register TmpReg = MRI.createGenericVirtualRegister(NarrowTy);
800       auto &MMO = **MI.memoperands_begin();
801       MIRBuilder.buildLoad(TmpReg, MI.getOperand(1).getReg(), MMO);
802       MIRBuilder.buildAnyExt(DstReg, TmpReg);
803       MI.eraseFromParent();
804       return Legalized;
805     }
806 
807     return reduceLoadStoreWidth(MI, TypeIdx, NarrowTy);
808   }
809   case TargetOpcode::G_ZEXTLOAD:
810   case TargetOpcode::G_SEXTLOAD: {
811     bool ZExt = MI.getOpcode() == TargetOpcode::G_ZEXTLOAD;
812     Register DstReg = MI.getOperand(0).getReg();
813     Register PtrReg = MI.getOperand(1).getReg();
814 
815     Register TmpReg = MRI.createGenericVirtualRegister(NarrowTy);
816     auto &MMO = **MI.memoperands_begin();
817     if (MMO.getSizeInBits() == NarrowSize) {
818       MIRBuilder.buildLoad(TmpReg, PtrReg, MMO);
819     } else {
820       unsigned ExtLoad = ZExt ? TargetOpcode::G_ZEXTLOAD
821         : TargetOpcode::G_SEXTLOAD;
822       MIRBuilder.buildInstr(ExtLoad)
823         .addDef(TmpReg)
824         .addUse(PtrReg)
825         .addMemOperand(&MMO);
826     }
827 
828     if (ZExt)
829       MIRBuilder.buildZExt(DstReg, TmpReg);
830     else
831       MIRBuilder.buildSExt(DstReg, TmpReg);
832 
833     MI.eraseFromParent();
834     return Legalized;
835   }
836   case TargetOpcode::G_STORE: {
837     const auto &MMO = **MI.memoperands_begin();
838 
839     Register SrcReg = MI.getOperand(0).getReg();
840     LLT SrcTy = MRI.getType(SrcReg);
841     if (SrcTy.isVector())
842       return UnableToLegalize;
843 
844     int NumParts = SizeOp0 / NarrowSize;
845     unsigned HandledSize = NumParts * NarrowTy.getSizeInBits();
846     unsigned LeftoverBits = SrcTy.getSizeInBits() - HandledSize;
847     if (SrcTy.isVector() && LeftoverBits != 0)
848       return UnableToLegalize;
849 
850     if (8 * MMO.getSize() != SrcTy.getSizeInBits()) {
851       Register TmpReg = MRI.createGenericVirtualRegister(NarrowTy);
852       auto &MMO = **MI.memoperands_begin();
853       MIRBuilder.buildTrunc(TmpReg, SrcReg);
854       MIRBuilder.buildStore(TmpReg, MI.getOperand(1).getReg(), MMO);
855       MI.eraseFromParent();
856       return Legalized;
857     }
858 
859     return reduceLoadStoreWidth(MI, 0, NarrowTy);
860   }
861   case TargetOpcode::G_SELECT:
862     return narrowScalarSelect(MI, TypeIdx, NarrowTy);
863   case TargetOpcode::G_AND:
864   case TargetOpcode::G_OR:
865   case TargetOpcode::G_XOR: {
866     // Legalize bitwise operation:
867     // A = BinOp<Ty> B, C
868     // into:
869     // B1, ..., BN = G_UNMERGE_VALUES B
870     // C1, ..., CN = G_UNMERGE_VALUES C
871     // A1 = BinOp<Ty/N> B1, C2
872     // ...
873     // AN = BinOp<Ty/N> BN, CN
874     // A = G_MERGE_VALUES A1, ..., AN
875     return narrowScalarBasic(MI, TypeIdx, NarrowTy);
876   }
877   case TargetOpcode::G_SHL:
878   case TargetOpcode::G_LSHR:
879   case TargetOpcode::G_ASHR:
880     return narrowScalarShift(MI, TypeIdx, NarrowTy);
881   case TargetOpcode::G_CTLZ:
882   case TargetOpcode::G_CTLZ_ZERO_UNDEF:
883   case TargetOpcode::G_CTTZ:
884   case TargetOpcode::G_CTTZ_ZERO_UNDEF:
885   case TargetOpcode::G_CTPOP:
886     if (TypeIdx != 0)
887       return UnableToLegalize; // TODO
888 
889     Observer.changingInstr(MI);
890     narrowScalarDst(MI, NarrowTy, 0, TargetOpcode::G_ZEXT);
891     Observer.changedInstr(MI);
892     return Legalized;
893   case TargetOpcode::G_INTTOPTR:
894     if (TypeIdx != 1)
895       return UnableToLegalize;
896 
897     Observer.changingInstr(MI);
898     narrowScalarSrc(MI, NarrowTy, 1);
899     Observer.changedInstr(MI);
900     return Legalized;
901   case TargetOpcode::G_PTRTOINT:
902     if (TypeIdx != 0)
903       return UnableToLegalize;
904 
905     Observer.changingInstr(MI);
906     narrowScalarDst(MI, NarrowTy, 0, TargetOpcode::G_ZEXT);
907     Observer.changedInstr(MI);
908     return Legalized;
909   case TargetOpcode::G_PHI: {
910     unsigned NumParts = SizeOp0 / NarrowSize;
911     SmallVector<Register, 2> DstRegs;
912     SmallVector<SmallVector<Register, 2>, 2> SrcRegs;
913     DstRegs.resize(NumParts);
914     SrcRegs.resize(MI.getNumOperands() / 2);
915     Observer.changingInstr(MI);
916     for (unsigned i = 1; i < MI.getNumOperands(); i += 2) {
917       MachineBasicBlock &OpMBB = *MI.getOperand(i + 1).getMBB();
918       MIRBuilder.setInsertPt(OpMBB, OpMBB.getFirstTerminator());
919       extractParts(MI.getOperand(i).getReg(), NarrowTy, NumParts,
920                    SrcRegs[i / 2]);
921     }
922     MachineBasicBlock &MBB = *MI.getParent();
923     MIRBuilder.setInsertPt(MBB, MI);
924     for (unsigned i = 0; i < NumParts; ++i) {
925       DstRegs[i] = MRI.createGenericVirtualRegister(NarrowTy);
926       MachineInstrBuilder MIB =
927           MIRBuilder.buildInstr(TargetOpcode::G_PHI).addDef(DstRegs[i]);
928       for (unsigned j = 1; j < MI.getNumOperands(); j += 2)
929         MIB.addUse(SrcRegs[j / 2][i]).add(MI.getOperand(j + 1));
930     }
931     MIRBuilder.setInsertPt(MBB, MBB.getFirstNonPHI());
932     MIRBuilder.buildMerge(MI.getOperand(0).getReg(), DstRegs);
933     Observer.changedInstr(MI);
934     MI.eraseFromParent();
935     return Legalized;
936   }
937   case TargetOpcode::G_EXTRACT_VECTOR_ELT:
938   case TargetOpcode::G_INSERT_VECTOR_ELT: {
939     if (TypeIdx != 2)
940       return UnableToLegalize;
941 
942     int OpIdx = MI.getOpcode() == TargetOpcode::G_EXTRACT_VECTOR_ELT ? 2 : 3;
943     Observer.changingInstr(MI);
944     narrowScalarSrc(MI, NarrowTy, OpIdx);
945     Observer.changedInstr(MI);
946     return Legalized;
947   }
948   case TargetOpcode::G_ICMP: {
949     uint64_t SrcSize = MRI.getType(MI.getOperand(2).getReg()).getSizeInBits();
950     if (NarrowSize * 2 != SrcSize)
951       return UnableToLegalize;
952 
953     Observer.changingInstr(MI);
954     Register LHSL = MRI.createGenericVirtualRegister(NarrowTy);
955     Register LHSH = MRI.createGenericVirtualRegister(NarrowTy);
956     MIRBuilder.buildUnmerge({LHSL, LHSH}, MI.getOperand(2).getReg());
957 
958     Register RHSL = MRI.createGenericVirtualRegister(NarrowTy);
959     Register RHSH = MRI.createGenericVirtualRegister(NarrowTy);
960     MIRBuilder.buildUnmerge({RHSL, RHSH}, MI.getOperand(3).getReg());
961 
962     CmpInst::Predicate Pred =
963         static_cast<CmpInst::Predicate>(MI.getOperand(1).getPredicate());
964     LLT ResTy = MRI.getType(MI.getOperand(0).getReg());
965 
966     if (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::ICMP_NE) {
967       MachineInstrBuilder XorL = MIRBuilder.buildXor(NarrowTy, LHSL, RHSL);
968       MachineInstrBuilder XorH = MIRBuilder.buildXor(NarrowTy, LHSH, RHSH);
969       MachineInstrBuilder Or = MIRBuilder.buildOr(NarrowTy, XorL, XorH);
970       MachineInstrBuilder Zero = MIRBuilder.buildConstant(NarrowTy, 0);
971       MIRBuilder.buildICmp(Pred, MI.getOperand(0).getReg(), Or, Zero);
972     } else {
973       MachineInstrBuilder CmpH = MIRBuilder.buildICmp(Pred, ResTy, LHSH, RHSH);
974       MachineInstrBuilder CmpHEQ =
975           MIRBuilder.buildICmp(CmpInst::Predicate::ICMP_EQ, ResTy, LHSH, RHSH);
976       MachineInstrBuilder CmpLU = MIRBuilder.buildICmp(
977           ICmpInst::getUnsignedPredicate(Pred), ResTy, LHSL, RHSL);
978       MIRBuilder.buildSelect(MI.getOperand(0).getReg(), CmpHEQ, CmpLU, CmpH);
979     }
980     Observer.changedInstr(MI);
981     MI.eraseFromParent();
982     return Legalized;
983   }
984   case TargetOpcode::G_SEXT_INREG: {
985     if (TypeIdx != 0)
986       return UnableToLegalize;
987 
988     if (!MI.getOperand(2).isImm())
989       return UnableToLegalize;
990     int64_t SizeInBits = MI.getOperand(2).getImm();
991 
992     // So long as the new type has more bits than the bits we're extending we
993     // don't need to break it apart.
994     if (NarrowTy.getScalarSizeInBits() >= SizeInBits) {
995       Observer.changingInstr(MI);
996       // We don't lose any non-extension bits by truncating the src and
997       // sign-extending the dst.
998       MachineOperand &MO1 = MI.getOperand(1);
999       auto TruncMIB = MIRBuilder.buildTrunc(NarrowTy, MO1.getReg());
1000       MO1.setReg(TruncMIB->getOperand(0).getReg());
1001 
1002       MachineOperand &MO2 = MI.getOperand(0);
1003       Register DstExt = MRI.createGenericVirtualRegister(NarrowTy);
1004       MIRBuilder.setInsertPt(MIRBuilder.getMBB(), ++MIRBuilder.getInsertPt());
1005       MIRBuilder.buildInstr(TargetOpcode::G_SEXT, {MO2.getReg()}, {DstExt});
1006       MO2.setReg(DstExt);
1007       Observer.changedInstr(MI);
1008       return Legalized;
1009     }
1010 
1011     // Break it apart. Components below the extension point are unmodified. The
1012     // component containing the extension point becomes a narrower SEXT_INREG.
1013     // Components above it are ashr'd from the component containing the
1014     // extension point.
1015     if (SizeOp0 % NarrowSize != 0)
1016       return UnableToLegalize;
1017     int NumParts = SizeOp0 / NarrowSize;
1018 
1019     // List the registers where the destination will be scattered.
1020     SmallVector<Register, 2> DstRegs;
1021     // List the registers where the source will be split.
1022     SmallVector<Register, 2> SrcRegs;
1023 
1024     // Create all the temporary registers.
1025     for (int i = 0; i < NumParts; ++i) {
1026       Register SrcReg = MRI.createGenericVirtualRegister(NarrowTy);
1027 
1028       SrcRegs.push_back(SrcReg);
1029     }
1030 
1031     // Explode the big arguments into smaller chunks.
1032     MIRBuilder.buildUnmerge(SrcRegs, MI.getOperand(1).getReg());
1033 
1034     Register AshrCstReg =
1035         MIRBuilder.buildConstant(NarrowTy, NarrowTy.getScalarSizeInBits() - 1)
1036             ->getOperand(0)
1037             .getReg();
1038     Register FullExtensionReg = 0;
1039     Register PartialExtensionReg = 0;
1040 
1041     // Do the operation on each small part.
1042     for (int i = 0; i < NumParts; ++i) {
1043       if ((i + 1) * NarrowTy.getScalarSizeInBits() < SizeInBits)
1044         DstRegs.push_back(SrcRegs[i]);
1045       else if (i * NarrowTy.getScalarSizeInBits() > SizeInBits) {
1046         assert(PartialExtensionReg &&
1047                "Expected to visit partial extension before full");
1048         if (FullExtensionReg) {
1049           DstRegs.push_back(FullExtensionReg);
1050           continue;
1051         }
1052         DstRegs.push_back(MIRBuilder
1053                               .buildInstr(TargetOpcode::G_ASHR, {NarrowTy},
1054                                           {PartialExtensionReg, AshrCstReg})
1055                               ->getOperand(0)
1056                               .getReg());
1057         FullExtensionReg = DstRegs.back();
1058       } else {
1059         DstRegs.push_back(
1060             MIRBuilder
1061                 .buildInstr(
1062                     TargetOpcode::G_SEXT_INREG, {NarrowTy},
1063                     {SrcRegs[i], SizeInBits % NarrowTy.getScalarSizeInBits()})
1064                 ->getOperand(0)
1065                 .getReg());
1066         PartialExtensionReg = DstRegs.back();
1067       }
1068     }
1069 
1070     // Gather the destination registers into the final destination.
1071     Register DstReg = MI.getOperand(0).getReg();
1072     MIRBuilder.buildMerge(DstReg, DstRegs);
1073     MI.eraseFromParent();
1074     return Legalized;
1075   }
1076   }
1077 }
1078 
1079 void LegalizerHelper::widenScalarSrc(MachineInstr &MI, LLT WideTy,
1080                                      unsigned OpIdx, unsigned ExtOpcode) {
1081   MachineOperand &MO = MI.getOperand(OpIdx);
1082   auto ExtB = MIRBuilder.buildInstr(ExtOpcode, {WideTy}, {MO.getReg()});
1083   MO.setReg(ExtB->getOperand(0).getReg());
1084 }
1085 
1086 void LegalizerHelper::narrowScalarSrc(MachineInstr &MI, LLT NarrowTy,
1087                                       unsigned OpIdx) {
1088   MachineOperand &MO = MI.getOperand(OpIdx);
1089   auto ExtB = MIRBuilder.buildInstr(TargetOpcode::G_TRUNC, {NarrowTy},
1090                                     {MO.getReg()});
1091   MO.setReg(ExtB->getOperand(0).getReg());
1092 }
1093 
1094 void LegalizerHelper::widenScalarDst(MachineInstr &MI, LLT WideTy,
1095                                      unsigned OpIdx, unsigned TruncOpcode) {
1096   MachineOperand &MO = MI.getOperand(OpIdx);
1097   Register DstExt = MRI.createGenericVirtualRegister(WideTy);
1098   MIRBuilder.setInsertPt(MIRBuilder.getMBB(), ++MIRBuilder.getInsertPt());
1099   MIRBuilder.buildInstr(TruncOpcode, {MO.getReg()}, {DstExt});
1100   MO.setReg(DstExt);
1101 }
1102 
1103 void LegalizerHelper::narrowScalarDst(MachineInstr &MI, LLT NarrowTy,
1104                                       unsigned OpIdx, unsigned ExtOpcode) {
1105   MachineOperand &MO = MI.getOperand(OpIdx);
1106   Register DstTrunc = MRI.createGenericVirtualRegister(NarrowTy);
1107   MIRBuilder.setInsertPt(MIRBuilder.getMBB(), ++MIRBuilder.getInsertPt());
1108   MIRBuilder.buildInstr(ExtOpcode, {MO.getReg()}, {DstTrunc});
1109   MO.setReg(DstTrunc);
1110 }
1111 
1112 void LegalizerHelper::moreElementsVectorDst(MachineInstr &MI, LLT WideTy,
1113                                             unsigned OpIdx) {
1114   MachineOperand &MO = MI.getOperand(OpIdx);
1115   Register DstExt = MRI.createGenericVirtualRegister(WideTy);
1116   MIRBuilder.setInsertPt(MIRBuilder.getMBB(), ++MIRBuilder.getInsertPt());
1117   MIRBuilder.buildExtract(MO.getReg(), DstExt, 0);
1118   MO.setReg(DstExt);
1119 }
1120 
1121 void LegalizerHelper::moreElementsVectorSrc(MachineInstr &MI, LLT MoreTy,
1122                                             unsigned OpIdx) {
1123   MachineOperand &MO = MI.getOperand(OpIdx);
1124 
1125   LLT OldTy = MRI.getType(MO.getReg());
1126   unsigned OldElts = OldTy.getNumElements();
1127   unsigned NewElts = MoreTy.getNumElements();
1128 
1129   unsigned NumParts = NewElts / OldElts;
1130 
1131   // Use concat_vectors if the result is a multiple of the number of elements.
1132   if (NumParts * OldElts == NewElts) {
1133     SmallVector<Register, 8> Parts;
1134     Parts.push_back(MO.getReg());
1135 
1136     Register ImpDef = MIRBuilder.buildUndef(OldTy).getReg(0);
1137     for (unsigned I = 1; I != NumParts; ++I)
1138       Parts.push_back(ImpDef);
1139 
1140     auto Concat = MIRBuilder.buildConcatVectors(MoreTy, Parts);
1141     MO.setReg(Concat.getReg(0));
1142     return;
1143   }
1144 
1145   Register MoreReg = MRI.createGenericVirtualRegister(MoreTy);
1146   Register ImpDef = MIRBuilder.buildUndef(MoreTy).getReg(0);
1147   MIRBuilder.buildInsert(MoreReg, ImpDef, MO.getReg(), 0);
1148   MO.setReg(MoreReg);
1149 }
1150 
1151 LegalizerHelper::LegalizeResult
1152 LegalizerHelper::widenScalarMergeValues(MachineInstr &MI, unsigned TypeIdx,
1153                                         LLT WideTy) {
1154   if (TypeIdx != 1)
1155     return UnableToLegalize;
1156 
1157   Register DstReg = MI.getOperand(0).getReg();
1158   LLT DstTy = MRI.getType(DstReg);
1159   if (DstTy.isVector())
1160     return UnableToLegalize;
1161 
1162   Register Src1 = MI.getOperand(1).getReg();
1163   LLT SrcTy = MRI.getType(Src1);
1164   const int DstSize = DstTy.getSizeInBits();
1165   const int SrcSize = SrcTy.getSizeInBits();
1166   const int WideSize = WideTy.getSizeInBits();
1167   const int NumMerge = (DstSize + WideSize - 1) / WideSize;
1168 
1169   unsigned NumOps = MI.getNumOperands();
1170   unsigned NumSrc = MI.getNumOperands() - 1;
1171   unsigned PartSize = DstTy.getSizeInBits() / NumSrc;
1172 
1173   if (WideSize >= DstSize) {
1174     // Directly pack the bits in the target type.
1175     Register ResultReg = MIRBuilder.buildZExt(WideTy, Src1).getReg(0);
1176 
1177     for (unsigned I = 2; I != NumOps; ++I) {
1178       const unsigned Offset = (I - 1) * PartSize;
1179 
1180       Register SrcReg = MI.getOperand(I).getReg();
1181       assert(MRI.getType(SrcReg) == LLT::scalar(PartSize));
1182 
1183       auto ZextInput = MIRBuilder.buildZExt(WideTy, SrcReg);
1184 
1185       Register NextResult = I + 1 == NumOps && WideTy == DstTy ? DstReg :
1186         MRI.createGenericVirtualRegister(WideTy);
1187 
1188       auto ShiftAmt = MIRBuilder.buildConstant(WideTy, Offset);
1189       auto Shl = MIRBuilder.buildShl(WideTy, ZextInput, ShiftAmt);
1190       MIRBuilder.buildOr(NextResult, ResultReg, Shl);
1191       ResultReg = NextResult;
1192     }
1193 
1194     if (WideSize > DstSize)
1195       MIRBuilder.buildTrunc(DstReg, ResultReg);
1196     else if (DstTy.isPointer())
1197       MIRBuilder.buildIntToPtr(DstReg, ResultReg);
1198 
1199     MI.eraseFromParent();
1200     return Legalized;
1201   }
1202 
1203   // Unmerge the original values to the GCD type, and recombine to the next
1204   // multiple greater than the original type.
1205   //
1206   // %3:_(s12) = G_MERGE_VALUES %0:_(s4), %1:_(s4), %2:_(s4) -> s6
1207   // %4:_(s2), %5:_(s2) = G_UNMERGE_VALUES %0
1208   // %6:_(s2), %7:_(s2) = G_UNMERGE_VALUES %1
1209   // %8:_(s2), %9:_(s2) = G_UNMERGE_VALUES %2
1210   // %10:_(s6) = G_MERGE_VALUES %4, %5, %6
1211   // %11:_(s6) = G_MERGE_VALUES %7, %8, %9
1212   // %12:_(s12) = G_MERGE_VALUES %10, %11
1213   //
1214   // Padding with undef if necessary:
1215   //
1216   // %2:_(s8) = G_MERGE_VALUES %0:_(s4), %1:_(s4) -> s6
1217   // %3:_(s2), %4:_(s2) = G_UNMERGE_VALUES %0
1218   // %5:_(s2), %6:_(s2) = G_UNMERGE_VALUES %1
1219   // %7:_(s2) = G_IMPLICIT_DEF
1220   // %8:_(s6) = G_MERGE_VALUES %3, %4, %5
1221   // %9:_(s6) = G_MERGE_VALUES %6, %7, %7
1222   // %10:_(s12) = G_MERGE_VALUES %8, %9
1223 
1224   const int GCD = greatestCommonDivisor(SrcSize, WideSize);
1225   LLT GCDTy = LLT::scalar(GCD);
1226 
1227   SmallVector<Register, 8> Parts;
1228   SmallVector<Register, 8> NewMergeRegs;
1229   SmallVector<Register, 8> Unmerges;
1230   LLT WideDstTy = LLT::scalar(NumMerge * WideSize);
1231 
1232   // Decompose the original operands if they don't evenly divide.
1233   for (int I = 1, E = MI.getNumOperands(); I != E; ++I) {
1234     Register SrcReg = MI.getOperand(I).getReg();
1235     if (GCD == SrcSize) {
1236       Unmerges.push_back(SrcReg);
1237     } else {
1238       auto Unmerge = MIRBuilder.buildUnmerge(GCDTy, SrcReg);
1239       for (int J = 0, JE = Unmerge->getNumOperands() - 1; J != JE; ++J)
1240         Unmerges.push_back(Unmerge.getReg(J));
1241     }
1242   }
1243 
1244   // Pad with undef to the next size that is a multiple of the requested size.
1245   if (static_cast<int>(Unmerges.size()) != NumMerge * WideSize) {
1246     Register UndefReg = MIRBuilder.buildUndef(GCDTy).getReg(0);
1247     for (int I = Unmerges.size(); I != NumMerge * WideSize; ++I)
1248       Unmerges.push_back(UndefReg);
1249   }
1250 
1251   const int PartsPerGCD = WideSize / GCD;
1252 
1253   // Build merges of each piece.
1254   ArrayRef<Register> Slicer(Unmerges);
1255   for (int I = 0; I != NumMerge; ++I, Slicer = Slicer.drop_front(PartsPerGCD)) {
1256     auto Merge = MIRBuilder.buildMerge(WideTy, Slicer.take_front(PartsPerGCD));
1257     NewMergeRegs.push_back(Merge.getReg(0));
1258   }
1259 
1260   // A truncate may be necessary if the requested type doesn't evenly divide the
1261   // original result type.
1262   if (DstTy.getSizeInBits() == WideDstTy.getSizeInBits()) {
1263     MIRBuilder.buildMerge(DstReg, NewMergeRegs);
1264   } else {
1265     auto FinalMerge = MIRBuilder.buildMerge(WideDstTy, NewMergeRegs);
1266     MIRBuilder.buildTrunc(DstReg, FinalMerge.getReg(0));
1267   }
1268 
1269   MI.eraseFromParent();
1270   return Legalized;
1271 }
1272 
1273 LegalizerHelper::LegalizeResult
1274 LegalizerHelper::widenScalarUnmergeValues(MachineInstr &MI, unsigned TypeIdx,
1275                                           LLT WideTy) {
1276   if (TypeIdx != 0)
1277     return UnableToLegalize;
1278 
1279   unsigned NumDst = MI.getNumOperands() - 1;
1280   Register SrcReg = MI.getOperand(NumDst).getReg();
1281   LLT SrcTy = MRI.getType(SrcReg);
1282   if (!SrcTy.isScalar())
1283     return UnableToLegalize;
1284 
1285   Register Dst0Reg = MI.getOperand(0).getReg();
1286   LLT DstTy = MRI.getType(Dst0Reg);
1287   if (!DstTy.isScalar())
1288     return UnableToLegalize;
1289 
1290   unsigned NewSrcSize = NumDst * WideTy.getSizeInBits();
1291   LLT NewSrcTy = LLT::scalar(NewSrcSize);
1292   unsigned SizeDiff = WideTy.getSizeInBits() - DstTy.getSizeInBits();
1293 
1294   auto WideSrc = MIRBuilder.buildZExt(NewSrcTy, SrcReg);
1295 
1296   for (unsigned I = 1; I != NumDst; ++I) {
1297     auto ShiftAmt = MIRBuilder.buildConstant(NewSrcTy, SizeDiff * I);
1298     auto Shl = MIRBuilder.buildShl(NewSrcTy, WideSrc, ShiftAmt);
1299     WideSrc = MIRBuilder.buildOr(NewSrcTy, WideSrc, Shl);
1300   }
1301 
1302   Observer.changingInstr(MI);
1303 
1304   MI.getOperand(NumDst).setReg(WideSrc->getOperand(0).getReg());
1305   for (unsigned I = 0; I != NumDst; ++I)
1306     widenScalarDst(MI, WideTy, I);
1307 
1308   Observer.changedInstr(MI);
1309 
1310   return Legalized;
1311 }
1312 
1313 LegalizerHelper::LegalizeResult
1314 LegalizerHelper::widenScalarExtract(MachineInstr &MI, unsigned TypeIdx,
1315                                     LLT WideTy) {
1316   Register DstReg = MI.getOperand(0).getReg();
1317   Register SrcReg = MI.getOperand(1).getReg();
1318   LLT SrcTy = MRI.getType(SrcReg);
1319 
1320   LLT DstTy = MRI.getType(DstReg);
1321   unsigned Offset = MI.getOperand(2).getImm();
1322 
1323   if (TypeIdx == 0) {
1324     if (SrcTy.isVector() || DstTy.isVector())
1325       return UnableToLegalize;
1326 
1327     SrcOp Src(SrcReg);
1328     if (SrcTy.isPointer()) {
1329       // Extracts from pointers can be handled only if they are really just
1330       // simple integers.
1331       const DataLayout &DL = MIRBuilder.getDataLayout();
1332       if (DL.isNonIntegralAddressSpace(SrcTy.getAddressSpace()))
1333         return UnableToLegalize;
1334 
1335       LLT SrcAsIntTy = LLT::scalar(SrcTy.getSizeInBits());
1336       Src = MIRBuilder.buildPtrToInt(SrcAsIntTy, Src);
1337       SrcTy = SrcAsIntTy;
1338     }
1339 
1340     if (DstTy.isPointer())
1341       return UnableToLegalize;
1342 
1343     if (Offset == 0) {
1344       // Avoid a shift in the degenerate case.
1345       MIRBuilder.buildTrunc(DstReg,
1346                             MIRBuilder.buildAnyExtOrTrunc(WideTy, Src));
1347       MI.eraseFromParent();
1348       return Legalized;
1349     }
1350 
1351     // Do a shift in the source type.
1352     LLT ShiftTy = SrcTy;
1353     if (WideTy.getSizeInBits() > SrcTy.getSizeInBits()) {
1354       Src = MIRBuilder.buildAnyExt(WideTy, Src);
1355       ShiftTy = WideTy;
1356     } else if (WideTy.getSizeInBits() > SrcTy.getSizeInBits())
1357       return UnableToLegalize;
1358 
1359     auto LShr = MIRBuilder.buildLShr(
1360       ShiftTy, Src, MIRBuilder.buildConstant(ShiftTy, Offset));
1361     MIRBuilder.buildTrunc(DstReg, LShr);
1362     MI.eraseFromParent();
1363     return Legalized;
1364   }
1365 
1366   if (SrcTy.isScalar()) {
1367     Observer.changingInstr(MI);
1368     widenScalarSrc(MI, WideTy, 1, TargetOpcode::G_ANYEXT);
1369     Observer.changedInstr(MI);
1370     return Legalized;
1371   }
1372 
1373   if (!SrcTy.isVector())
1374     return UnableToLegalize;
1375 
1376   if (DstTy != SrcTy.getElementType())
1377     return UnableToLegalize;
1378 
1379   if (Offset % SrcTy.getScalarSizeInBits() != 0)
1380     return UnableToLegalize;
1381 
1382   Observer.changingInstr(MI);
1383   widenScalarSrc(MI, WideTy, 1, TargetOpcode::G_ANYEXT);
1384 
1385   MI.getOperand(2).setImm((WideTy.getSizeInBits() / SrcTy.getSizeInBits()) *
1386                           Offset);
1387   widenScalarDst(MI, WideTy.getScalarType(), 0);
1388   Observer.changedInstr(MI);
1389   return Legalized;
1390 }
1391 
1392 LegalizerHelper::LegalizeResult
1393 LegalizerHelper::widenScalarInsert(MachineInstr &MI, unsigned TypeIdx,
1394                                    LLT WideTy) {
1395   if (TypeIdx != 0)
1396     return UnableToLegalize;
1397   Observer.changingInstr(MI);
1398   widenScalarSrc(MI, WideTy, 1, TargetOpcode::G_ANYEXT);
1399   widenScalarDst(MI, WideTy);
1400   Observer.changedInstr(MI);
1401   return Legalized;
1402 }
1403 
1404 LegalizerHelper::LegalizeResult
1405 LegalizerHelper::widenScalar(MachineInstr &MI, unsigned TypeIdx, LLT WideTy) {
1406   MIRBuilder.setInstr(MI);
1407 
1408   switch (MI.getOpcode()) {
1409   default:
1410     return UnableToLegalize;
1411   case TargetOpcode::G_EXTRACT:
1412     return widenScalarExtract(MI, TypeIdx, WideTy);
1413   case TargetOpcode::G_INSERT:
1414     return widenScalarInsert(MI, TypeIdx, WideTy);
1415   case TargetOpcode::G_MERGE_VALUES:
1416     return widenScalarMergeValues(MI, TypeIdx, WideTy);
1417   case TargetOpcode::G_UNMERGE_VALUES:
1418     return widenScalarUnmergeValues(MI, TypeIdx, WideTy);
1419   case TargetOpcode::G_UADDO:
1420   case TargetOpcode::G_USUBO: {
1421     if (TypeIdx == 1)
1422       return UnableToLegalize; // TODO
1423     auto LHSZext = MIRBuilder.buildInstr(TargetOpcode::G_ZEXT, {WideTy},
1424                                          {MI.getOperand(2).getReg()});
1425     auto RHSZext = MIRBuilder.buildInstr(TargetOpcode::G_ZEXT, {WideTy},
1426                                          {MI.getOperand(3).getReg()});
1427     unsigned Opcode = MI.getOpcode() == TargetOpcode::G_UADDO
1428                           ? TargetOpcode::G_ADD
1429                           : TargetOpcode::G_SUB;
1430     // Do the arithmetic in the larger type.
1431     auto NewOp = MIRBuilder.buildInstr(Opcode, {WideTy}, {LHSZext, RHSZext});
1432     LLT OrigTy = MRI.getType(MI.getOperand(0).getReg());
1433     APInt Mask = APInt::getAllOnesValue(OrigTy.getSizeInBits());
1434     auto AndOp = MIRBuilder.buildInstr(
1435         TargetOpcode::G_AND, {WideTy},
1436         {NewOp, MIRBuilder.buildConstant(WideTy, Mask.getZExtValue())});
1437     // There is no overflow if the AndOp is the same as NewOp.
1438     MIRBuilder.buildICmp(CmpInst::ICMP_NE, MI.getOperand(1).getReg(), NewOp,
1439                          AndOp);
1440     // Now trunc the NewOp to the original result.
1441     MIRBuilder.buildTrunc(MI.getOperand(0).getReg(), NewOp);
1442     MI.eraseFromParent();
1443     return Legalized;
1444   }
1445   case TargetOpcode::G_CTTZ:
1446   case TargetOpcode::G_CTTZ_ZERO_UNDEF:
1447   case TargetOpcode::G_CTLZ:
1448   case TargetOpcode::G_CTLZ_ZERO_UNDEF:
1449   case TargetOpcode::G_CTPOP: {
1450     if (TypeIdx == 0) {
1451       Observer.changingInstr(MI);
1452       widenScalarDst(MI, WideTy, 0);
1453       Observer.changedInstr(MI);
1454       return Legalized;
1455     }
1456 
1457     Register SrcReg = MI.getOperand(1).getReg();
1458 
1459     // First ZEXT the input.
1460     auto MIBSrc = MIRBuilder.buildZExt(WideTy, SrcReg);
1461     LLT CurTy = MRI.getType(SrcReg);
1462     if (MI.getOpcode() == TargetOpcode::G_CTTZ) {
1463       // The count is the same in the larger type except if the original
1464       // value was zero.  This can be handled by setting the bit just off
1465       // the top of the original type.
1466       auto TopBit =
1467           APInt::getOneBitSet(WideTy.getSizeInBits(), CurTy.getSizeInBits());
1468       MIBSrc = MIRBuilder.buildOr(
1469         WideTy, MIBSrc, MIRBuilder.buildConstant(WideTy, TopBit));
1470     }
1471 
1472     // Perform the operation at the larger size.
1473     auto MIBNewOp = MIRBuilder.buildInstr(MI.getOpcode(), {WideTy}, {MIBSrc});
1474     // This is already the correct result for CTPOP and CTTZs
1475     if (MI.getOpcode() == TargetOpcode::G_CTLZ ||
1476         MI.getOpcode() == TargetOpcode::G_CTLZ_ZERO_UNDEF) {
1477       // The correct result is NewOp - (Difference in widety and current ty).
1478       unsigned SizeDiff = WideTy.getSizeInBits() - CurTy.getSizeInBits();
1479       MIBNewOp = MIRBuilder.buildInstr(
1480           TargetOpcode::G_SUB, {WideTy},
1481           {MIBNewOp, MIRBuilder.buildConstant(WideTy, SizeDiff)});
1482     }
1483 
1484     MIRBuilder.buildZExtOrTrunc(MI.getOperand(0), MIBNewOp);
1485     MI.eraseFromParent();
1486     return Legalized;
1487   }
1488   case TargetOpcode::G_BSWAP: {
1489     Observer.changingInstr(MI);
1490     Register DstReg = MI.getOperand(0).getReg();
1491 
1492     Register ShrReg = MRI.createGenericVirtualRegister(WideTy);
1493     Register DstExt = MRI.createGenericVirtualRegister(WideTy);
1494     Register ShiftAmtReg = MRI.createGenericVirtualRegister(WideTy);
1495     widenScalarSrc(MI, WideTy, 1, TargetOpcode::G_ANYEXT);
1496 
1497     MI.getOperand(0).setReg(DstExt);
1498 
1499     MIRBuilder.setInsertPt(MIRBuilder.getMBB(), ++MIRBuilder.getInsertPt());
1500 
1501     LLT Ty = MRI.getType(DstReg);
1502     unsigned DiffBits = WideTy.getScalarSizeInBits() - Ty.getScalarSizeInBits();
1503     MIRBuilder.buildConstant(ShiftAmtReg, DiffBits);
1504     MIRBuilder.buildInstr(TargetOpcode::G_LSHR)
1505       .addDef(ShrReg)
1506       .addUse(DstExt)
1507       .addUse(ShiftAmtReg);
1508 
1509     MIRBuilder.buildTrunc(DstReg, ShrReg);
1510     Observer.changedInstr(MI);
1511     return Legalized;
1512   }
1513   case TargetOpcode::G_BITREVERSE: {
1514     Observer.changingInstr(MI);
1515 
1516     Register DstReg = MI.getOperand(0).getReg();
1517     LLT Ty = MRI.getType(DstReg);
1518     unsigned DiffBits = WideTy.getScalarSizeInBits() - Ty.getScalarSizeInBits();
1519 
1520     Register DstExt = MRI.createGenericVirtualRegister(WideTy);
1521     widenScalarSrc(MI, WideTy, 1, TargetOpcode::G_ANYEXT);
1522     MI.getOperand(0).setReg(DstExt);
1523     MIRBuilder.setInsertPt(MIRBuilder.getMBB(), ++MIRBuilder.getInsertPt());
1524 
1525     auto ShiftAmt = MIRBuilder.buildConstant(WideTy, DiffBits);
1526     auto Shift = MIRBuilder.buildLShr(WideTy, DstExt, ShiftAmt);
1527     MIRBuilder.buildTrunc(DstReg, Shift);
1528     Observer.changedInstr(MI);
1529     return Legalized;
1530   }
1531   case TargetOpcode::G_ADD:
1532   case TargetOpcode::G_AND:
1533   case TargetOpcode::G_MUL:
1534   case TargetOpcode::G_OR:
1535   case TargetOpcode::G_XOR:
1536   case TargetOpcode::G_SUB:
1537     // Perform operation at larger width (any extension is fines here, high bits
1538     // don't affect the result) and then truncate the result back to the
1539     // original type.
1540     Observer.changingInstr(MI);
1541     widenScalarSrc(MI, WideTy, 1, TargetOpcode::G_ANYEXT);
1542     widenScalarSrc(MI, WideTy, 2, TargetOpcode::G_ANYEXT);
1543     widenScalarDst(MI, WideTy);
1544     Observer.changedInstr(MI);
1545     return Legalized;
1546 
1547   case TargetOpcode::G_SHL:
1548     Observer.changingInstr(MI);
1549 
1550     if (TypeIdx == 0) {
1551       widenScalarSrc(MI, WideTy, 1, TargetOpcode::G_ANYEXT);
1552       widenScalarDst(MI, WideTy);
1553     } else {
1554       assert(TypeIdx == 1);
1555       // The "number of bits to shift" operand must preserve its value as an
1556       // unsigned integer:
1557       widenScalarSrc(MI, WideTy, 2, TargetOpcode::G_ZEXT);
1558     }
1559 
1560     Observer.changedInstr(MI);
1561     return Legalized;
1562 
1563   case TargetOpcode::G_SDIV:
1564   case TargetOpcode::G_SREM:
1565   case TargetOpcode::G_SMIN:
1566   case TargetOpcode::G_SMAX:
1567     Observer.changingInstr(MI);
1568     widenScalarSrc(MI, WideTy, 1, TargetOpcode::G_SEXT);
1569     widenScalarSrc(MI, WideTy, 2, TargetOpcode::G_SEXT);
1570     widenScalarDst(MI, WideTy);
1571     Observer.changedInstr(MI);
1572     return Legalized;
1573 
1574   case TargetOpcode::G_ASHR:
1575   case TargetOpcode::G_LSHR:
1576     Observer.changingInstr(MI);
1577 
1578     if (TypeIdx == 0) {
1579       unsigned CvtOp = MI.getOpcode() == TargetOpcode::G_ASHR ?
1580         TargetOpcode::G_SEXT : TargetOpcode::G_ZEXT;
1581 
1582       widenScalarSrc(MI, WideTy, 1, CvtOp);
1583       widenScalarDst(MI, WideTy);
1584     } else {
1585       assert(TypeIdx == 1);
1586       // The "number of bits to shift" operand must preserve its value as an
1587       // unsigned integer:
1588       widenScalarSrc(MI, WideTy, 2, TargetOpcode::G_ZEXT);
1589     }
1590 
1591     Observer.changedInstr(MI);
1592     return Legalized;
1593   case TargetOpcode::G_UDIV:
1594   case TargetOpcode::G_UREM:
1595   case TargetOpcode::G_UMIN:
1596   case TargetOpcode::G_UMAX:
1597     Observer.changingInstr(MI);
1598     widenScalarSrc(MI, WideTy, 1, TargetOpcode::G_ZEXT);
1599     widenScalarSrc(MI, WideTy, 2, TargetOpcode::G_ZEXT);
1600     widenScalarDst(MI, WideTy);
1601     Observer.changedInstr(MI);
1602     return Legalized;
1603 
1604   case TargetOpcode::G_SELECT:
1605     Observer.changingInstr(MI);
1606     if (TypeIdx == 0) {
1607       // Perform operation at larger width (any extension is fine here, high
1608       // bits don't affect the result) and then truncate the result back to the
1609       // original type.
1610       widenScalarSrc(MI, WideTy, 2, TargetOpcode::G_ANYEXT);
1611       widenScalarSrc(MI, WideTy, 3, TargetOpcode::G_ANYEXT);
1612       widenScalarDst(MI, WideTy);
1613     } else {
1614       bool IsVec = MRI.getType(MI.getOperand(1).getReg()).isVector();
1615       // Explicit extension is required here since high bits affect the result.
1616       widenScalarSrc(MI, WideTy, 1, MIRBuilder.getBoolExtOp(IsVec, false));
1617     }
1618     Observer.changedInstr(MI);
1619     return Legalized;
1620 
1621   case TargetOpcode::G_FPTOSI:
1622   case TargetOpcode::G_FPTOUI:
1623     if (TypeIdx != 0)
1624       return UnableToLegalize;
1625     Observer.changingInstr(MI);
1626     widenScalarDst(MI, WideTy);
1627     Observer.changedInstr(MI);
1628     return Legalized;
1629 
1630   case TargetOpcode::G_SITOFP:
1631     if (TypeIdx != 1)
1632       return UnableToLegalize;
1633     Observer.changingInstr(MI);
1634     widenScalarSrc(MI, WideTy, 1, TargetOpcode::G_SEXT);
1635     Observer.changedInstr(MI);
1636     return Legalized;
1637 
1638   case TargetOpcode::G_UITOFP:
1639     if (TypeIdx != 1)
1640       return UnableToLegalize;
1641     Observer.changingInstr(MI);
1642     widenScalarSrc(MI, WideTy, 1, TargetOpcode::G_ZEXT);
1643     Observer.changedInstr(MI);
1644     return Legalized;
1645 
1646   case TargetOpcode::G_LOAD:
1647   case TargetOpcode::G_SEXTLOAD:
1648   case TargetOpcode::G_ZEXTLOAD:
1649     Observer.changingInstr(MI);
1650     widenScalarDst(MI, WideTy);
1651     Observer.changedInstr(MI);
1652     return Legalized;
1653 
1654   case TargetOpcode::G_STORE: {
1655     if (TypeIdx != 0)
1656       return UnableToLegalize;
1657 
1658     LLT Ty = MRI.getType(MI.getOperand(0).getReg());
1659     if (!isPowerOf2_32(Ty.getSizeInBits()))
1660       return UnableToLegalize;
1661 
1662     Observer.changingInstr(MI);
1663 
1664     unsigned ExtType = Ty.getScalarSizeInBits() == 1 ?
1665       TargetOpcode::G_ZEXT : TargetOpcode::G_ANYEXT;
1666     widenScalarSrc(MI, WideTy, 0, ExtType);
1667 
1668     Observer.changedInstr(MI);
1669     return Legalized;
1670   }
1671   case TargetOpcode::G_CONSTANT: {
1672     MachineOperand &SrcMO = MI.getOperand(1);
1673     LLVMContext &Ctx = MIRBuilder.getMF().getFunction().getContext();
1674     const APInt &Val = SrcMO.getCImm()->getValue().sext(WideTy.getSizeInBits());
1675     Observer.changingInstr(MI);
1676     SrcMO.setCImm(ConstantInt::get(Ctx, Val));
1677 
1678     widenScalarDst(MI, WideTy);
1679     Observer.changedInstr(MI);
1680     return Legalized;
1681   }
1682   case TargetOpcode::G_FCONSTANT: {
1683     MachineOperand &SrcMO = MI.getOperand(1);
1684     LLVMContext &Ctx = MIRBuilder.getMF().getFunction().getContext();
1685     APFloat Val = SrcMO.getFPImm()->getValueAPF();
1686     bool LosesInfo;
1687     switch (WideTy.getSizeInBits()) {
1688     case 32:
1689       Val.convert(APFloat::IEEEsingle(), APFloat::rmNearestTiesToEven,
1690                   &LosesInfo);
1691       break;
1692     case 64:
1693       Val.convert(APFloat::IEEEdouble(), APFloat::rmNearestTiesToEven,
1694                   &LosesInfo);
1695       break;
1696     default:
1697       return UnableToLegalize;
1698     }
1699 
1700     assert(!LosesInfo && "extend should always be lossless");
1701 
1702     Observer.changingInstr(MI);
1703     SrcMO.setFPImm(ConstantFP::get(Ctx, Val));
1704 
1705     widenScalarDst(MI, WideTy, 0, TargetOpcode::G_FPTRUNC);
1706     Observer.changedInstr(MI);
1707     return Legalized;
1708   }
1709   case TargetOpcode::G_IMPLICIT_DEF: {
1710     Observer.changingInstr(MI);
1711     widenScalarDst(MI, WideTy);
1712     Observer.changedInstr(MI);
1713     return Legalized;
1714   }
1715   case TargetOpcode::G_BRCOND:
1716     Observer.changingInstr(MI);
1717     widenScalarSrc(MI, WideTy, 0, MIRBuilder.getBoolExtOp(false, false));
1718     Observer.changedInstr(MI);
1719     return Legalized;
1720 
1721   case TargetOpcode::G_FCMP:
1722     Observer.changingInstr(MI);
1723     if (TypeIdx == 0)
1724       widenScalarDst(MI, WideTy);
1725     else {
1726       widenScalarSrc(MI, WideTy, 2, TargetOpcode::G_FPEXT);
1727       widenScalarSrc(MI, WideTy, 3, TargetOpcode::G_FPEXT);
1728     }
1729     Observer.changedInstr(MI);
1730     return Legalized;
1731 
1732   case TargetOpcode::G_ICMP:
1733     Observer.changingInstr(MI);
1734     if (TypeIdx == 0)
1735       widenScalarDst(MI, WideTy);
1736     else {
1737       unsigned ExtOpcode = CmpInst::isSigned(static_cast<CmpInst::Predicate>(
1738                                MI.getOperand(1).getPredicate()))
1739                                ? TargetOpcode::G_SEXT
1740                                : TargetOpcode::G_ZEXT;
1741       widenScalarSrc(MI, WideTy, 2, ExtOpcode);
1742       widenScalarSrc(MI, WideTy, 3, ExtOpcode);
1743     }
1744     Observer.changedInstr(MI);
1745     return Legalized;
1746 
1747   case TargetOpcode::G_GEP:
1748     assert(TypeIdx == 1 && "unable to legalize pointer of GEP");
1749     Observer.changingInstr(MI);
1750     widenScalarSrc(MI, WideTy, 2, TargetOpcode::G_SEXT);
1751     Observer.changedInstr(MI);
1752     return Legalized;
1753 
1754   case TargetOpcode::G_PHI: {
1755     assert(TypeIdx == 0 && "Expecting only Idx 0");
1756 
1757     Observer.changingInstr(MI);
1758     for (unsigned I = 1; I < MI.getNumOperands(); I += 2) {
1759       MachineBasicBlock &OpMBB = *MI.getOperand(I + 1).getMBB();
1760       MIRBuilder.setInsertPt(OpMBB, OpMBB.getFirstTerminator());
1761       widenScalarSrc(MI, WideTy, I, TargetOpcode::G_ANYEXT);
1762     }
1763 
1764     MachineBasicBlock &MBB = *MI.getParent();
1765     MIRBuilder.setInsertPt(MBB, --MBB.getFirstNonPHI());
1766     widenScalarDst(MI, WideTy);
1767     Observer.changedInstr(MI);
1768     return Legalized;
1769   }
1770   case TargetOpcode::G_EXTRACT_VECTOR_ELT: {
1771     if (TypeIdx == 0) {
1772       Register VecReg = MI.getOperand(1).getReg();
1773       LLT VecTy = MRI.getType(VecReg);
1774       Observer.changingInstr(MI);
1775 
1776       widenScalarSrc(MI, LLT::vector(VecTy.getNumElements(),
1777                                      WideTy.getSizeInBits()),
1778                      1, TargetOpcode::G_SEXT);
1779 
1780       widenScalarDst(MI, WideTy, 0);
1781       Observer.changedInstr(MI);
1782       return Legalized;
1783     }
1784 
1785     if (TypeIdx != 2)
1786       return UnableToLegalize;
1787     Observer.changingInstr(MI);
1788     widenScalarSrc(MI, WideTy, 2, TargetOpcode::G_SEXT);
1789     Observer.changedInstr(MI);
1790     return Legalized;
1791   }
1792   case TargetOpcode::G_FADD:
1793   case TargetOpcode::G_FMUL:
1794   case TargetOpcode::G_FSUB:
1795   case TargetOpcode::G_FMA:
1796   case TargetOpcode::G_FMAD:
1797   case TargetOpcode::G_FNEG:
1798   case TargetOpcode::G_FABS:
1799   case TargetOpcode::G_FCANONICALIZE:
1800   case TargetOpcode::G_FMINNUM:
1801   case TargetOpcode::G_FMAXNUM:
1802   case TargetOpcode::G_FMINNUM_IEEE:
1803   case TargetOpcode::G_FMAXNUM_IEEE:
1804   case TargetOpcode::G_FMINIMUM:
1805   case TargetOpcode::G_FMAXIMUM:
1806   case TargetOpcode::G_FDIV:
1807   case TargetOpcode::G_FREM:
1808   case TargetOpcode::G_FCEIL:
1809   case TargetOpcode::G_FFLOOR:
1810   case TargetOpcode::G_FCOS:
1811   case TargetOpcode::G_FSIN:
1812   case TargetOpcode::G_FLOG10:
1813   case TargetOpcode::G_FLOG:
1814   case TargetOpcode::G_FLOG2:
1815   case TargetOpcode::G_FRINT:
1816   case TargetOpcode::G_FNEARBYINT:
1817   case TargetOpcode::G_FSQRT:
1818   case TargetOpcode::G_FEXP:
1819   case TargetOpcode::G_FEXP2:
1820   case TargetOpcode::G_FPOW:
1821   case TargetOpcode::G_INTRINSIC_TRUNC:
1822   case TargetOpcode::G_INTRINSIC_ROUND:
1823     assert(TypeIdx == 0);
1824     Observer.changingInstr(MI);
1825 
1826     for (unsigned I = 1, E = MI.getNumOperands(); I != E; ++I)
1827       widenScalarSrc(MI, WideTy, I, TargetOpcode::G_FPEXT);
1828 
1829     widenScalarDst(MI, WideTy, 0, TargetOpcode::G_FPTRUNC);
1830     Observer.changedInstr(MI);
1831     return Legalized;
1832   case TargetOpcode::G_INTTOPTR:
1833     if (TypeIdx != 1)
1834       return UnableToLegalize;
1835 
1836     Observer.changingInstr(MI);
1837     widenScalarSrc(MI, WideTy, 1, TargetOpcode::G_ZEXT);
1838     Observer.changedInstr(MI);
1839     return Legalized;
1840   case TargetOpcode::G_PTRTOINT:
1841     if (TypeIdx != 0)
1842       return UnableToLegalize;
1843 
1844     Observer.changingInstr(MI);
1845     widenScalarDst(MI, WideTy, 0);
1846     Observer.changedInstr(MI);
1847     return Legalized;
1848   case TargetOpcode::G_BUILD_VECTOR: {
1849     Observer.changingInstr(MI);
1850 
1851     const LLT WideEltTy = TypeIdx == 1 ? WideTy : WideTy.getElementType();
1852     for (int I = 1, E = MI.getNumOperands(); I != E; ++I)
1853       widenScalarSrc(MI, WideEltTy, I, TargetOpcode::G_ANYEXT);
1854 
1855     // Avoid changing the result vector type if the source element type was
1856     // requested.
1857     if (TypeIdx == 1) {
1858       auto &TII = *MI.getMF()->getSubtarget().getInstrInfo();
1859       MI.setDesc(TII.get(TargetOpcode::G_BUILD_VECTOR_TRUNC));
1860     } else {
1861       widenScalarDst(MI, WideTy, 0);
1862     }
1863 
1864     Observer.changedInstr(MI);
1865     return Legalized;
1866   }
1867   case TargetOpcode::G_SEXT_INREG:
1868     if (TypeIdx != 0)
1869       return UnableToLegalize;
1870 
1871     Observer.changingInstr(MI);
1872     widenScalarSrc(MI, WideTy, 1, TargetOpcode::G_ANYEXT);
1873     widenScalarDst(MI, WideTy, 0, TargetOpcode::G_TRUNC);
1874     Observer.changedInstr(MI);
1875     return Legalized;
1876   }
1877 }
1878 
1879 LegalizerHelper::LegalizeResult
1880 LegalizerHelper::lower(MachineInstr &MI, unsigned TypeIdx, LLT Ty) {
1881   using namespace TargetOpcode;
1882   MIRBuilder.setInstr(MI);
1883 
1884   switch(MI.getOpcode()) {
1885   default:
1886     return UnableToLegalize;
1887   case TargetOpcode::G_SREM:
1888   case TargetOpcode::G_UREM: {
1889     Register QuotReg = MRI.createGenericVirtualRegister(Ty);
1890     MIRBuilder.buildInstr(MI.getOpcode() == G_SREM ? G_SDIV : G_UDIV)
1891         .addDef(QuotReg)
1892         .addUse(MI.getOperand(1).getReg())
1893         .addUse(MI.getOperand(2).getReg());
1894 
1895     Register ProdReg = MRI.createGenericVirtualRegister(Ty);
1896     MIRBuilder.buildMul(ProdReg, QuotReg, MI.getOperand(2).getReg());
1897     MIRBuilder.buildSub(MI.getOperand(0).getReg(), MI.getOperand(1).getReg(),
1898                         ProdReg);
1899     MI.eraseFromParent();
1900     return Legalized;
1901   }
1902   case TargetOpcode::G_SMULO:
1903   case TargetOpcode::G_UMULO: {
1904     // Generate G_UMULH/G_SMULH to check for overflow and a normal G_MUL for the
1905     // result.
1906     Register Res = MI.getOperand(0).getReg();
1907     Register Overflow = MI.getOperand(1).getReg();
1908     Register LHS = MI.getOperand(2).getReg();
1909     Register RHS = MI.getOperand(3).getReg();
1910 
1911     MIRBuilder.buildMul(Res, LHS, RHS);
1912 
1913     unsigned Opcode = MI.getOpcode() == TargetOpcode::G_SMULO
1914                           ? TargetOpcode::G_SMULH
1915                           : TargetOpcode::G_UMULH;
1916 
1917     Register HiPart = MRI.createGenericVirtualRegister(Ty);
1918     MIRBuilder.buildInstr(Opcode)
1919       .addDef(HiPart)
1920       .addUse(LHS)
1921       .addUse(RHS);
1922 
1923     Register Zero = MRI.createGenericVirtualRegister(Ty);
1924     MIRBuilder.buildConstant(Zero, 0);
1925 
1926     // For *signed* multiply, overflow is detected by checking:
1927     // (hi != (lo >> bitwidth-1))
1928     if (Opcode == TargetOpcode::G_SMULH) {
1929       Register Shifted = MRI.createGenericVirtualRegister(Ty);
1930       Register ShiftAmt = MRI.createGenericVirtualRegister(Ty);
1931       MIRBuilder.buildConstant(ShiftAmt, Ty.getSizeInBits() - 1);
1932       MIRBuilder.buildInstr(TargetOpcode::G_ASHR)
1933         .addDef(Shifted)
1934         .addUse(Res)
1935         .addUse(ShiftAmt);
1936       MIRBuilder.buildICmp(CmpInst::ICMP_NE, Overflow, HiPart, Shifted);
1937     } else {
1938       MIRBuilder.buildICmp(CmpInst::ICMP_NE, Overflow, HiPart, Zero);
1939     }
1940     MI.eraseFromParent();
1941     return Legalized;
1942   }
1943   case TargetOpcode::G_FNEG: {
1944     // TODO: Handle vector types once we are able to
1945     // represent them.
1946     if (Ty.isVector())
1947       return UnableToLegalize;
1948     Register Res = MI.getOperand(0).getReg();
1949     Type *ZeroTy;
1950     LLVMContext &Ctx = MIRBuilder.getMF().getFunction().getContext();
1951     switch (Ty.getSizeInBits()) {
1952     case 16:
1953       ZeroTy = Type::getHalfTy(Ctx);
1954       break;
1955     case 32:
1956       ZeroTy = Type::getFloatTy(Ctx);
1957       break;
1958     case 64:
1959       ZeroTy = Type::getDoubleTy(Ctx);
1960       break;
1961     case 128:
1962       ZeroTy = Type::getFP128Ty(Ctx);
1963       break;
1964     default:
1965       llvm_unreachable("unexpected floating-point type");
1966     }
1967     ConstantFP &ZeroForNegation =
1968         *cast<ConstantFP>(ConstantFP::getZeroValueForNegation(ZeroTy));
1969     auto Zero = MIRBuilder.buildFConstant(Ty, ZeroForNegation);
1970     Register SubByReg = MI.getOperand(1).getReg();
1971     Register ZeroReg = Zero->getOperand(0).getReg();
1972     MIRBuilder.buildInstr(TargetOpcode::G_FSUB, {Res}, {ZeroReg, SubByReg},
1973                           MI.getFlags());
1974     MI.eraseFromParent();
1975     return Legalized;
1976   }
1977   case TargetOpcode::G_FSUB: {
1978     // Lower (G_FSUB LHS, RHS) to (G_FADD LHS, (G_FNEG RHS)).
1979     // First, check if G_FNEG is marked as Lower. If so, we may
1980     // end up with an infinite loop as G_FSUB is used to legalize G_FNEG.
1981     if (LI.getAction({G_FNEG, {Ty}}).Action == Lower)
1982       return UnableToLegalize;
1983     Register Res = MI.getOperand(0).getReg();
1984     Register LHS = MI.getOperand(1).getReg();
1985     Register RHS = MI.getOperand(2).getReg();
1986     Register Neg = MRI.createGenericVirtualRegister(Ty);
1987     MIRBuilder.buildInstr(TargetOpcode::G_FNEG).addDef(Neg).addUse(RHS);
1988     MIRBuilder.buildInstr(TargetOpcode::G_FADD, {Res}, {LHS, Neg}, MI.getFlags());
1989     MI.eraseFromParent();
1990     return Legalized;
1991   }
1992   case TargetOpcode::G_FMAD:
1993     return lowerFMad(MI);
1994   case TargetOpcode::G_ATOMIC_CMPXCHG_WITH_SUCCESS: {
1995     Register OldValRes = MI.getOperand(0).getReg();
1996     Register SuccessRes = MI.getOperand(1).getReg();
1997     Register Addr = MI.getOperand(2).getReg();
1998     Register CmpVal = MI.getOperand(3).getReg();
1999     Register NewVal = MI.getOperand(4).getReg();
2000     MIRBuilder.buildAtomicCmpXchg(OldValRes, Addr, CmpVal, NewVal,
2001                                   **MI.memoperands_begin());
2002     MIRBuilder.buildICmp(CmpInst::ICMP_EQ, SuccessRes, OldValRes, CmpVal);
2003     MI.eraseFromParent();
2004     return Legalized;
2005   }
2006   case TargetOpcode::G_LOAD:
2007   case TargetOpcode::G_SEXTLOAD:
2008   case TargetOpcode::G_ZEXTLOAD: {
2009     // Lower to a memory-width G_LOAD and a G_SEXT/G_ZEXT/G_ANYEXT
2010     Register DstReg = MI.getOperand(0).getReg();
2011     Register PtrReg = MI.getOperand(1).getReg();
2012     LLT DstTy = MRI.getType(DstReg);
2013     auto &MMO = **MI.memoperands_begin();
2014 
2015     if (DstTy.getSizeInBits() == MMO.getSizeInBits()) {
2016       if (MI.getOpcode() == TargetOpcode::G_LOAD) {
2017         // This load needs splitting into power of 2 sized loads.
2018         if (DstTy.isVector())
2019           return UnableToLegalize;
2020         if (isPowerOf2_32(DstTy.getSizeInBits()))
2021           return UnableToLegalize; // Don't know what we're being asked to do.
2022 
2023         // Our strategy here is to generate anyextending loads for the smaller
2024         // types up to next power-2 result type, and then combine the two larger
2025         // result values together, before truncating back down to the non-pow-2
2026         // type.
2027         // E.g. v1 = i24 load =>
2028         // v2 = i32 load (2 byte)
2029         // v3 = i32 load (1 byte)
2030         // v4 = i32 shl v3, 16
2031         // v5 = i32 or v4, v2
2032         // v1 = i24 trunc v5
2033         // By doing this we generate the correct truncate which should get
2034         // combined away as an artifact with a matching extend.
2035         uint64_t LargeSplitSize = PowerOf2Floor(DstTy.getSizeInBits());
2036         uint64_t SmallSplitSize = DstTy.getSizeInBits() - LargeSplitSize;
2037 
2038         MachineFunction &MF = MIRBuilder.getMF();
2039         MachineMemOperand *LargeMMO =
2040             MF.getMachineMemOperand(&MMO, 0, LargeSplitSize / 8);
2041         MachineMemOperand *SmallMMO = MF.getMachineMemOperand(
2042             &MMO, LargeSplitSize / 8, SmallSplitSize / 8);
2043 
2044         LLT PtrTy = MRI.getType(PtrReg);
2045         unsigned AnyExtSize = NextPowerOf2(DstTy.getSizeInBits());
2046         LLT AnyExtTy = LLT::scalar(AnyExtSize);
2047         Register LargeLdReg = MRI.createGenericVirtualRegister(AnyExtTy);
2048         Register SmallLdReg = MRI.createGenericVirtualRegister(AnyExtTy);
2049         auto LargeLoad =
2050             MIRBuilder.buildLoad(LargeLdReg, PtrReg, *LargeMMO);
2051 
2052         auto OffsetCst =
2053             MIRBuilder.buildConstant(LLT::scalar(64), LargeSplitSize / 8);
2054         Register GEPReg = MRI.createGenericVirtualRegister(PtrTy);
2055         auto SmallPtr = MIRBuilder.buildGEP(GEPReg, PtrReg, OffsetCst.getReg(0));
2056         auto SmallLoad = MIRBuilder.buildLoad(SmallLdReg, SmallPtr.getReg(0),
2057                                               *SmallMMO);
2058 
2059         auto ShiftAmt = MIRBuilder.buildConstant(AnyExtTy, LargeSplitSize);
2060         auto Shift = MIRBuilder.buildShl(AnyExtTy, SmallLoad, ShiftAmt);
2061         auto Or = MIRBuilder.buildOr(AnyExtTy, Shift, LargeLoad);
2062         MIRBuilder.buildTrunc(DstReg, {Or.getReg(0)});
2063         MI.eraseFromParent();
2064         return Legalized;
2065       }
2066       MIRBuilder.buildLoad(DstReg, PtrReg, MMO);
2067       MI.eraseFromParent();
2068       return Legalized;
2069     }
2070 
2071     if (DstTy.isScalar()) {
2072       Register TmpReg =
2073           MRI.createGenericVirtualRegister(LLT::scalar(MMO.getSizeInBits()));
2074       MIRBuilder.buildLoad(TmpReg, PtrReg, MMO);
2075       switch (MI.getOpcode()) {
2076       default:
2077         llvm_unreachable("Unexpected opcode");
2078       case TargetOpcode::G_LOAD:
2079         MIRBuilder.buildAnyExt(DstReg, TmpReg);
2080         break;
2081       case TargetOpcode::G_SEXTLOAD:
2082         MIRBuilder.buildSExt(DstReg, TmpReg);
2083         break;
2084       case TargetOpcode::G_ZEXTLOAD:
2085         MIRBuilder.buildZExt(DstReg, TmpReg);
2086         break;
2087       }
2088       MI.eraseFromParent();
2089       return Legalized;
2090     }
2091 
2092     return UnableToLegalize;
2093   }
2094   case TargetOpcode::G_STORE: {
2095     // Lower a non-power of 2 store into multiple pow-2 stores.
2096     // E.g. split an i24 store into an i16 store + i8 store.
2097     // We do this by first extending the stored value to the next largest power
2098     // of 2 type, and then using truncating stores to store the components.
2099     // By doing this, likewise with G_LOAD, generate an extend that can be
2100     // artifact-combined away instead of leaving behind extracts.
2101     Register SrcReg = MI.getOperand(0).getReg();
2102     Register PtrReg = MI.getOperand(1).getReg();
2103     LLT SrcTy = MRI.getType(SrcReg);
2104     MachineMemOperand &MMO = **MI.memoperands_begin();
2105     if (SrcTy.getSizeInBits() != MMO.getSizeInBits())
2106       return UnableToLegalize;
2107     if (SrcTy.isVector())
2108       return UnableToLegalize;
2109     if (isPowerOf2_32(SrcTy.getSizeInBits()))
2110       return UnableToLegalize; // Don't know what we're being asked to do.
2111 
2112     // Extend to the next pow-2.
2113     const LLT ExtendTy = LLT::scalar(NextPowerOf2(SrcTy.getSizeInBits()));
2114     auto ExtVal = MIRBuilder.buildAnyExt(ExtendTy, SrcReg);
2115 
2116     // Obtain the smaller value by shifting away the larger value.
2117     uint64_t LargeSplitSize = PowerOf2Floor(SrcTy.getSizeInBits());
2118     uint64_t SmallSplitSize = SrcTy.getSizeInBits() - LargeSplitSize;
2119     auto ShiftAmt = MIRBuilder.buildConstant(ExtendTy, LargeSplitSize);
2120     auto SmallVal = MIRBuilder.buildLShr(ExtendTy, ExtVal, ShiftAmt);
2121 
2122     // Generate the GEP and truncating stores.
2123     LLT PtrTy = MRI.getType(PtrReg);
2124     auto OffsetCst =
2125         MIRBuilder.buildConstant(LLT::scalar(64), LargeSplitSize / 8);
2126     Register GEPReg = MRI.createGenericVirtualRegister(PtrTy);
2127     auto SmallPtr = MIRBuilder.buildGEP(GEPReg, PtrReg, OffsetCst.getReg(0));
2128 
2129     MachineFunction &MF = MIRBuilder.getMF();
2130     MachineMemOperand *LargeMMO =
2131         MF.getMachineMemOperand(&MMO, 0, LargeSplitSize / 8);
2132     MachineMemOperand *SmallMMO =
2133         MF.getMachineMemOperand(&MMO, LargeSplitSize / 8, SmallSplitSize / 8);
2134     MIRBuilder.buildStore(ExtVal.getReg(0), PtrReg, *LargeMMO);
2135     MIRBuilder.buildStore(SmallVal.getReg(0), SmallPtr.getReg(0), *SmallMMO);
2136     MI.eraseFromParent();
2137     return Legalized;
2138   }
2139   case TargetOpcode::G_CTLZ_ZERO_UNDEF:
2140   case TargetOpcode::G_CTTZ_ZERO_UNDEF:
2141   case TargetOpcode::G_CTLZ:
2142   case TargetOpcode::G_CTTZ:
2143   case TargetOpcode::G_CTPOP:
2144     return lowerBitCount(MI, TypeIdx, Ty);
2145   case G_UADDO: {
2146     Register Res = MI.getOperand(0).getReg();
2147     Register CarryOut = MI.getOperand(1).getReg();
2148     Register LHS = MI.getOperand(2).getReg();
2149     Register RHS = MI.getOperand(3).getReg();
2150 
2151     MIRBuilder.buildAdd(Res, LHS, RHS);
2152     MIRBuilder.buildICmp(CmpInst::ICMP_ULT, CarryOut, Res, RHS);
2153 
2154     MI.eraseFromParent();
2155     return Legalized;
2156   }
2157   case G_UADDE: {
2158     Register Res = MI.getOperand(0).getReg();
2159     Register CarryOut = MI.getOperand(1).getReg();
2160     Register LHS = MI.getOperand(2).getReg();
2161     Register RHS = MI.getOperand(3).getReg();
2162     Register CarryIn = MI.getOperand(4).getReg();
2163 
2164     Register TmpRes = MRI.createGenericVirtualRegister(Ty);
2165     Register ZExtCarryIn = MRI.createGenericVirtualRegister(Ty);
2166 
2167     MIRBuilder.buildAdd(TmpRes, LHS, RHS);
2168     MIRBuilder.buildZExt(ZExtCarryIn, CarryIn);
2169     MIRBuilder.buildAdd(Res, TmpRes, ZExtCarryIn);
2170     MIRBuilder.buildICmp(CmpInst::ICMP_ULT, CarryOut, Res, LHS);
2171 
2172     MI.eraseFromParent();
2173     return Legalized;
2174   }
2175   case G_USUBO: {
2176     Register Res = MI.getOperand(0).getReg();
2177     Register BorrowOut = MI.getOperand(1).getReg();
2178     Register LHS = MI.getOperand(2).getReg();
2179     Register RHS = MI.getOperand(3).getReg();
2180 
2181     MIRBuilder.buildSub(Res, LHS, RHS);
2182     MIRBuilder.buildICmp(CmpInst::ICMP_ULT, BorrowOut, LHS, RHS);
2183 
2184     MI.eraseFromParent();
2185     return Legalized;
2186   }
2187   case G_USUBE: {
2188     Register Res = MI.getOperand(0).getReg();
2189     Register BorrowOut = MI.getOperand(1).getReg();
2190     Register LHS = MI.getOperand(2).getReg();
2191     Register RHS = MI.getOperand(3).getReg();
2192     Register BorrowIn = MI.getOperand(4).getReg();
2193 
2194     Register TmpRes = MRI.createGenericVirtualRegister(Ty);
2195     Register ZExtBorrowIn = MRI.createGenericVirtualRegister(Ty);
2196     Register LHS_EQ_RHS = MRI.createGenericVirtualRegister(LLT::scalar(1));
2197     Register LHS_ULT_RHS = MRI.createGenericVirtualRegister(LLT::scalar(1));
2198 
2199     MIRBuilder.buildSub(TmpRes, LHS, RHS);
2200     MIRBuilder.buildZExt(ZExtBorrowIn, BorrowIn);
2201     MIRBuilder.buildSub(Res, TmpRes, ZExtBorrowIn);
2202     MIRBuilder.buildICmp(CmpInst::ICMP_EQ, LHS_EQ_RHS, LHS, RHS);
2203     MIRBuilder.buildICmp(CmpInst::ICMP_ULT, LHS_ULT_RHS, LHS, RHS);
2204     MIRBuilder.buildSelect(BorrowOut, LHS_EQ_RHS, BorrowIn, LHS_ULT_RHS);
2205 
2206     MI.eraseFromParent();
2207     return Legalized;
2208   }
2209   case G_UITOFP:
2210     return lowerUITOFP(MI, TypeIdx, Ty);
2211   case G_SITOFP:
2212     return lowerSITOFP(MI, TypeIdx, Ty);
2213   case G_FPTOUI:
2214     return lowerFPTOUI(MI, TypeIdx, Ty);
2215   case G_SMIN:
2216   case G_SMAX:
2217   case G_UMIN:
2218   case G_UMAX:
2219     return lowerMinMax(MI, TypeIdx, Ty);
2220   case G_FCOPYSIGN:
2221     return lowerFCopySign(MI, TypeIdx, Ty);
2222   case G_FMINNUM:
2223   case G_FMAXNUM:
2224     return lowerFMinNumMaxNum(MI);
2225   case G_UNMERGE_VALUES:
2226     return lowerUnmergeValues(MI);
2227   case TargetOpcode::G_SEXT_INREG: {
2228     assert(MI.getOperand(2).isImm() && "Expected immediate");
2229     int64_t SizeInBits = MI.getOperand(2).getImm();
2230 
2231     Register DstReg = MI.getOperand(0).getReg();
2232     Register SrcReg = MI.getOperand(1).getReg();
2233     LLT DstTy = MRI.getType(DstReg);
2234     Register TmpRes = MRI.createGenericVirtualRegister(DstTy);
2235 
2236     auto MIBSz = MIRBuilder.buildConstant(DstTy, DstTy.getScalarSizeInBits() - SizeInBits);
2237     MIRBuilder.buildInstr(TargetOpcode::G_SHL, {TmpRes}, {SrcReg, MIBSz->getOperand(0).getReg()});
2238     MIRBuilder.buildInstr(TargetOpcode::G_ASHR, {DstReg}, {TmpRes, MIBSz->getOperand(0).getReg()});
2239     MI.eraseFromParent();
2240     return Legalized;
2241   }
2242   case G_SHUFFLE_VECTOR:
2243     return lowerShuffleVector(MI);
2244   case G_DYN_STACKALLOC:
2245     return lowerDynStackAlloc(MI);
2246   }
2247 }
2248 
2249 LegalizerHelper::LegalizeResult LegalizerHelper::fewerElementsVectorImplicitDef(
2250     MachineInstr &MI, unsigned TypeIdx, LLT NarrowTy) {
2251   SmallVector<Register, 2> DstRegs;
2252 
2253   unsigned NarrowSize = NarrowTy.getSizeInBits();
2254   Register DstReg = MI.getOperand(0).getReg();
2255   unsigned Size = MRI.getType(DstReg).getSizeInBits();
2256   int NumParts = Size / NarrowSize;
2257   // FIXME: Don't know how to handle the situation where the small vectors
2258   // aren't all the same size yet.
2259   if (Size % NarrowSize != 0)
2260     return UnableToLegalize;
2261 
2262   for (int i = 0; i < NumParts; ++i) {
2263     Register TmpReg = MRI.createGenericVirtualRegister(NarrowTy);
2264     MIRBuilder.buildUndef(TmpReg);
2265     DstRegs.push_back(TmpReg);
2266   }
2267 
2268   if (NarrowTy.isVector())
2269     MIRBuilder.buildConcatVectors(DstReg, DstRegs);
2270   else
2271     MIRBuilder.buildBuildVector(DstReg, DstRegs);
2272 
2273   MI.eraseFromParent();
2274   return Legalized;
2275 }
2276 
2277 LegalizerHelper::LegalizeResult
2278 LegalizerHelper::fewerElementsVectorBasic(MachineInstr &MI, unsigned TypeIdx,
2279                                           LLT NarrowTy) {
2280   const unsigned Opc = MI.getOpcode();
2281   const unsigned NumOps = MI.getNumOperands() - 1;
2282   const unsigned NarrowSize = NarrowTy.getSizeInBits();
2283   const Register DstReg = MI.getOperand(0).getReg();
2284   const unsigned Flags = MI.getFlags();
2285   const LLT DstTy = MRI.getType(DstReg);
2286   const unsigned Size = DstTy.getSizeInBits();
2287   const int NumParts = Size / NarrowSize;
2288   const LLT EltTy = DstTy.getElementType();
2289   const unsigned EltSize = EltTy.getSizeInBits();
2290   const unsigned BitsForNumParts = NarrowSize * NumParts;
2291 
2292   // Check if we have any leftovers. If we do, then only handle the case where
2293   // the leftover is one element.
2294   if (BitsForNumParts != Size && BitsForNumParts + EltSize != Size)
2295     return UnableToLegalize;
2296 
2297   if (BitsForNumParts != Size) {
2298     Register AccumDstReg = MRI.createGenericVirtualRegister(DstTy);
2299     MIRBuilder.buildUndef(AccumDstReg);
2300 
2301     // Handle the pieces which evenly divide into the requested type with
2302     // extract/op/insert sequence.
2303     for (unsigned Offset = 0; Offset < BitsForNumParts; Offset += NarrowSize) {
2304       SmallVector<SrcOp, 4> SrcOps;
2305       for (unsigned I = 1, E = MI.getNumOperands(); I != E; ++I) {
2306         Register PartOpReg = MRI.createGenericVirtualRegister(NarrowTy);
2307         MIRBuilder.buildExtract(PartOpReg, MI.getOperand(I).getReg(), Offset);
2308         SrcOps.push_back(PartOpReg);
2309       }
2310 
2311       Register PartDstReg = MRI.createGenericVirtualRegister(NarrowTy);
2312       MIRBuilder.buildInstr(Opc, {PartDstReg}, SrcOps, Flags);
2313 
2314       Register PartInsertReg = MRI.createGenericVirtualRegister(DstTy);
2315       MIRBuilder.buildInsert(PartInsertReg, AccumDstReg, PartDstReg, Offset);
2316       AccumDstReg = PartInsertReg;
2317     }
2318 
2319     // Handle the remaining element sized leftover piece.
2320     SmallVector<SrcOp, 4> SrcOps;
2321     for (unsigned I = 1, E = MI.getNumOperands(); I != E; ++I) {
2322       Register PartOpReg = MRI.createGenericVirtualRegister(EltTy);
2323       MIRBuilder.buildExtract(PartOpReg, MI.getOperand(I).getReg(),
2324                               BitsForNumParts);
2325       SrcOps.push_back(PartOpReg);
2326     }
2327 
2328     Register PartDstReg = MRI.createGenericVirtualRegister(EltTy);
2329     MIRBuilder.buildInstr(Opc, {PartDstReg}, SrcOps, Flags);
2330     MIRBuilder.buildInsert(DstReg, AccumDstReg, PartDstReg, BitsForNumParts);
2331     MI.eraseFromParent();
2332 
2333     return Legalized;
2334   }
2335 
2336   SmallVector<Register, 2> DstRegs, Src0Regs, Src1Regs, Src2Regs;
2337 
2338   extractParts(MI.getOperand(1).getReg(), NarrowTy, NumParts, Src0Regs);
2339 
2340   if (NumOps >= 2)
2341     extractParts(MI.getOperand(2).getReg(), NarrowTy, NumParts, Src1Regs);
2342 
2343   if (NumOps >= 3)
2344     extractParts(MI.getOperand(3).getReg(), NarrowTy, NumParts, Src2Regs);
2345 
2346   for (int i = 0; i < NumParts; ++i) {
2347     Register DstReg = MRI.createGenericVirtualRegister(NarrowTy);
2348 
2349     if (NumOps == 1)
2350       MIRBuilder.buildInstr(Opc, {DstReg}, {Src0Regs[i]}, Flags);
2351     else if (NumOps == 2) {
2352       MIRBuilder.buildInstr(Opc, {DstReg}, {Src0Regs[i], Src1Regs[i]}, Flags);
2353     } else if (NumOps == 3) {
2354       MIRBuilder.buildInstr(Opc, {DstReg},
2355                             {Src0Regs[i], Src1Regs[i], Src2Regs[i]}, Flags);
2356     }
2357 
2358     DstRegs.push_back(DstReg);
2359   }
2360 
2361   if (NarrowTy.isVector())
2362     MIRBuilder.buildConcatVectors(DstReg, DstRegs);
2363   else
2364     MIRBuilder.buildBuildVector(DstReg, DstRegs);
2365 
2366   MI.eraseFromParent();
2367   return Legalized;
2368 }
2369 
2370 // Handle splitting vector operations which need to have the same number of
2371 // elements in each type index, but each type index may have a different element
2372 // type.
2373 //
2374 // e.g.  <4 x s64> = G_SHL <4 x s64>, <4 x s32> ->
2375 //       <2 x s64> = G_SHL <2 x s64>, <2 x s32>
2376 //       <2 x s64> = G_SHL <2 x s64>, <2 x s32>
2377 //
2378 // Also handles some irregular breakdown cases, e.g.
2379 // e.g.  <3 x s64> = G_SHL <3 x s64>, <3 x s32> ->
2380 //       <2 x s64> = G_SHL <2 x s64>, <2 x s32>
2381 //             s64 = G_SHL s64, s32
2382 LegalizerHelper::LegalizeResult
2383 LegalizerHelper::fewerElementsVectorMultiEltType(
2384   MachineInstr &MI, unsigned TypeIdx, LLT NarrowTyArg) {
2385   if (TypeIdx != 0)
2386     return UnableToLegalize;
2387 
2388   const LLT NarrowTy0 = NarrowTyArg;
2389   const unsigned NewNumElts =
2390       NarrowTy0.isVector() ? NarrowTy0.getNumElements() : 1;
2391 
2392   const Register DstReg = MI.getOperand(0).getReg();
2393   LLT DstTy = MRI.getType(DstReg);
2394   LLT LeftoverTy0;
2395 
2396   // All of the operands need to have the same number of elements, so if we can
2397   // determine a type breakdown for the result type, we can for all of the
2398   // source types.
2399   int NumParts = getNarrowTypeBreakDown(DstTy, NarrowTy0, LeftoverTy0).first;
2400   if (NumParts < 0)
2401     return UnableToLegalize;
2402 
2403   SmallVector<MachineInstrBuilder, 4> NewInsts;
2404 
2405   SmallVector<Register, 4> DstRegs, LeftoverDstRegs;
2406   SmallVector<Register, 4> PartRegs, LeftoverRegs;
2407 
2408   for (unsigned I = 1, E = MI.getNumOperands(); I != E; ++I) {
2409     LLT LeftoverTy;
2410     Register SrcReg = MI.getOperand(I).getReg();
2411     LLT SrcTyI = MRI.getType(SrcReg);
2412     LLT NarrowTyI = LLT::scalarOrVector(NewNumElts, SrcTyI.getScalarType());
2413     LLT LeftoverTyI;
2414 
2415     // Split this operand into the requested typed registers, and any leftover
2416     // required to reproduce the original type.
2417     if (!extractParts(SrcReg, SrcTyI, NarrowTyI, LeftoverTyI, PartRegs,
2418                       LeftoverRegs))
2419       return UnableToLegalize;
2420 
2421     if (I == 1) {
2422       // For the first operand, create an instruction for each part and setup
2423       // the result.
2424       for (Register PartReg : PartRegs) {
2425         Register PartDstReg = MRI.createGenericVirtualRegister(NarrowTy0);
2426         NewInsts.push_back(MIRBuilder.buildInstrNoInsert(MI.getOpcode())
2427                                .addDef(PartDstReg)
2428                                .addUse(PartReg));
2429         DstRegs.push_back(PartDstReg);
2430       }
2431 
2432       for (Register LeftoverReg : LeftoverRegs) {
2433         Register PartDstReg = MRI.createGenericVirtualRegister(LeftoverTy0);
2434         NewInsts.push_back(MIRBuilder.buildInstrNoInsert(MI.getOpcode())
2435                                .addDef(PartDstReg)
2436                                .addUse(LeftoverReg));
2437         LeftoverDstRegs.push_back(PartDstReg);
2438       }
2439     } else {
2440       assert(NewInsts.size() == PartRegs.size() + LeftoverRegs.size());
2441 
2442       // Add the newly created operand splits to the existing instructions. The
2443       // odd-sized pieces are ordered after the requested NarrowTyArg sized
2444       // pieces.
2445       unsigned InstCount = 0;
2446       for (unsigned J = 0, JE = PartRegs.size(); J != JE; ++J)
2447         NewInsts[InstCount++].addUse(PartRegs[J]);
2448       for (unsigned J = 0, JE = LeftoverRegs.size(); J != JE; ++J)
2449         NewInsts[InstCount++].addUse(LeftoverRegs[J]);
2450     }
2451 
2452     PartRegs.clear();
2453     LeftoverRegs.clear();
2454   }
2455 
2456   // Insert the newly built operations and rebuild the result register.
2457   for (auto &MIB : NewInsts)
2458     MIRBuilder.insertInstr(MIB);
2459 
2460   insertParts(DstReg, DstTy, NarrowTy0, DstRegs, LeftoverTy0, LeftoverDstRegs);
2461 
2462   MI.eraseFromParent();
2463   return Legalized;
2464 }
2465 
2466 LegalizerHelper::LegalizeResult
2467 LegalizerHelper::fewerElementsVectorCasts(MachineInstr &MI, unsigned TypeIdx,
2468                                           LLT NarrowTy) {
2469   if (TypeIdx != 0)
2470     return UnableToLegalize;
2471 
2472   Register DstReg = MI.getOperand(0).getReg();
2473   Register SrcReg = MI.getOperand(1).getReg();
2474   LLT DstTy = MRI.getType(DstReg);
2475   LLT SrcTy = MRI.getType(SrcReg);
2476 
2477   LLT NarrowTy0 = NarrowTy;
2478   LLT NarrowTy1;
2479   unsigned NumParts;
2480 
2481   if (NarrowTy.isVector()) {
2482     // Uneven breakdown not handled.
2483     NumParts = DstTy.getNumElements() / NarrowTy.getNumElements();
2484     if (NumParts * NarrowTy.getNumElements() != DstTy.getNumElements())
2485       return UnableToLegalize;
2486 
2487     NarrowTy1 = LLT::vector(NumParts, SrcTy.getElementType().getSizeInBits());
2488   } else {
2489     NumParts = DstTy.getNumElements();
2490     NarrowTy1 = SrcTy.getElementType();
2491   }
2492 
2493   SmallVector<Register, 4> SrcRegs, DstRegs;
2494   extractParts(SrcReg, NarrowTy1, NumParts, SrcRegs);
2495 
2496   for (unsigned I = 0; I < NumParts; ++I) {
2497     Register DstReg = MRI.createGenericVirtualRegister(NarrowTy0);
2498     MachineInstr *NewInst = MIRBuilder.buildInstr(MI.getOpcode())
2499       .addDef(DstReg)
2500       .addUse(SrcRegs[I]);
2501 
2502     NewInst->setFlags(MI.getFlags());
2503     DstRegs.push_back(DstReg);
2504   }
2505 
2506   if (NarrowTy.isVector())
2507     MIRBuilder.buildConcatVectors(DstReg, DstRegs);
2508   else
2509     MIRBuilder.buildBuildVector(DstReg, DstRegs);
2510 
2511   MI.eraseFromParent();
2512   return Legalized;
2513 }
2514 
2515 LegalizerHelper::LegalizeResult
2516 LegalizerHelper::fewerElementsVectorCmp(MachineInstr &MI, unsigned TypeIdx,
2517                                         LLT NarrowTy) {
2518   Register DstReg = MI.getOperand(0).getReg();
2519   Register Src0Reg = MI.getOperand(2).getReg();
2520   LLT DstTy = MRI.getType(DstReg);
2521   LLT SrcTy = MRI.getType(Src0Reg);
2522 
2523   unsigned NumParts;
2524   LLT NarrowTy0, NarrowTy1;
2525 
2526   if (TypeIdx == 0) {
2527     unsigned NewElts = NarrowTy.isVector() ? NarrowTy.getNumElements() : 1;
2528     unsigned OldElts = DstTy.getNumElements();
2529 
2530     NarrowTy0 = NarrowTy;
2531     NumParts = NarrowTy.isVector() ? (OldElts / NewElts) : DstTy.getNumElements();
2532     NarrowTy1 = NarrowTy.isVector() ?
2533       LLT::vector(NarrowTy.getNumElements(), SrcTy.getScalarSizeInBits()) :
2534       SrcTy.getElementType();
2535 
2536   } else {
2537     unsigned NewElts = NarrowTy.isVector() ? NarrowTy.getNumElements() : 1;
2538     unsigned OldElts = SrcTy.getNumElements();
2539 
2540     NumParts = NarrowTy.isVector() ? (OldElts / NewElts) :
2541       NarrowTy.getNumElements();
2542     NarrowTy0 = LLT::vector(NarrowTy.getNumElements(),
2543                             DstTy.getScalarSizeInBits());
2544     NarrowTy1 = NarrowTy;
2545   }
2546 
2547   // FIXME: Don't know how to handle the situation where the small vectors
2548   // aren't all the same size yet.
2549   if (NarrowTy1.isVector() &&
2550       NarrowTy1.getNumElements() * NumParts != DstTy.getNumElements())
2551     return UnableToLegalize;
2552 
2553   CmpInst::Predicate Pred
2554     = static_cast<CmpInst::Predicate>(MI.getOperand(1).getPredicate());
2555 
2556   SmallVector<Register, 2> Src1Regs, Src2Regs, DstRegs;
2557   extractParts(MI.getOperand(2).getReg(), NarrowTy1, NumParts, Src1Regs);
2558   extractParts(MI.getOperand(3).getReg(), NarrowTy1, NumParts, Src2Regs);
2559 
2560   for (unsigned I = 0; I < NumParts; ++I) {
2561     Register DstReg = MRI.createGenericVirtualRegister(NarrowTy0);
2562     DstRegs.push_back(DstReg);
2563 
2564     if (MI.getOpcode() == TargetOpcode::G_ICMP)
2565       MIRBuilder.buildICmp(Pred, DstReg, Src1Regs[I], Src2Regs[I]);
2566     else {
2567       MachineInstr *NewCmp
2568         = MIRBuilder.buildFCmp(Pred, DstReg, Src1Regs[I], Src2Regs[I]);
2569       NewCmp->setFlags(MI.getFlags());
2570     }
2571   }
2572 
2573   if (NarrowTy1.isVector())
2574     MIRBuilder.buildConcatVectors(DstReg, DstRegs);
2575   else
2576     MIRBuilder.buildBuildVector(DstReg, DstRegs);
2577 
2578   MI.eraseFromParent();
2579   return Legalized;
2580 }
2581 
2582 LegalizerHelper::LegalizeResult
2583 LegalizerHelper::fewerElementsVectorSelect(MachineInstr &MI, unsigned TypeIdx,
2584                                            LLT NarrowTy) {
2585   Register DstReg = MI.getOperand(0).getReg();
2586   Register CondReg = MI.getOperand(1).getReg();
2587 
2588   unsigned NumParts = 0;
2589   LLT NarrowTy0, NarrowTy1;
2590 
2591   LLT DstTy = MRI.getType(DstReg);
2592   LLT CondTy = MRI.getType(CondReg);
2593   unsigned Size = DstTy.getSizeInBits();
2594 
2595   assert(TypeIdx == 0 || CondTy.isVector());
2596 
2597   if (TypeIdx == 0) {
2598     NarrowTy0 = NarrowTy;
2599     NarrowTy1 = CondTy;
2600 
2601     unsigned NarrowSize = NarrowTy0.getSizeInBits();
2602     // FIXME: Don't know how to handle the situation where the small vectors
2603     // aren't all the same size yet.
2604     if (Size % NarrowSize != 0)
2605       return UnableToLegalize;
2606 
2607     NumParts = Size / NarrowSize;
2608 
2609     // Need to break down the condition type
2610     if (CondTy.isVector()) {
2611       if (CondTy.getNumElements() == NumParts)
2612         NarrowTy1 = CondTy.getElementType();
2613       else
2614         NarrowTy1 = LLT::vector(CondTy.getNumElements() / NumParts,
2615                                 CondTy.getScalarSizeInBits());
2616     }
2617   } else {
2618     NumParts = CondTy.getNumElements();
2619     if (NarrowTy.isVector()) {
2620       // TODO: Handle uneven breakdown.
2621       if (NumParts * NarrowTy.getNumElements() != CondTy.getNumElements())
2622         return UnableToLegalize;
2623 
2624       return UnableToLegalize;
2625     } else {
2626       NarrowTy0 = DstTy.getElementType();
2627       NarrowTy1 = NarrowTy;
2628     }
2629   }
2630 
2631   SmallVector<Register, 2> DstRegs, Src0Regs, Src1Regs, Src2Regs;
2632   if (CondTy.isVector())
2633     extractParts(MI.getOperand(1).getReg(), NarrowTy1, NumParts, Src0Regs);
2634 
2635   extractParts(MI.getOperand(2).getReg(), NarrowTy0, NumParts, Src1Regs);
2636   extractParts(MI.getOperand(3).getReg(), NarrowTy0, NumParts, Src2Regs);
2637 
2638   for (unsigned i = 0; i < NumParts; ++i) {
2639     Register DstReg = MRI.createGenericVirtualRegister(NarrowTy0);
2640     MIRBuilder.buildSelect(DstReg, CondTy.isVector() ? Src0Regs[i] : CondReg,
2641                            Src1Regs[i], Src2Regs[i]);
2642     DstRegs.push_back(DstReg);
2643   }
2644 
2645   if (NarrowTy0.isVector())
2646     MIRBuilder.buildConcatVectors(DstReg, DstRegs);
2647   else
2648     MIRBuilder.buildBuildVector(DstReg, DstRegs);
2649 
2650   MI.eraseFromParent();
2651   return Legalized;
2652 }
2653 
2654 LegalizerHelper::LegalizeResult
2655 LegalizerHelper::fewerElementsVectorPhi(MachineInstr &MI, unsigned TypeIdx,
2656                                         LLT NarrowTy) {
2657   const Register DstReg = MI.getOperand(0).getReg();
2658   LLT PhiTy = MRI.getType(DstReg);
2659   LLT LeftoverTy;
2660 
2661   // All of the operands need to have the same number of elements, so if we can
2662   // determine a type breakdown for the result type, we can for all of the
2663   // source types.
2664   int NumParts, NumLeftover;
2665   std::tie(NumParts, NumLeftover)
2666     = getNarrowTypeBreakDown(PhiTy, NarrowTy, LeftoverTy);
2667   if (NumParts < 0)
2668     return UnableToLegalize;
2669 
2670   SmallVector<Register, 4> DstRegs, LeftoverDstRegs;
2671   SmallVector<MachineInstrBuilder, 4> NewInsts;
2672 
2673   const int TotalNumParts = NumParts + NumLeftover;
2674 
2675   // Insert the new phis in the result block first.
2676   for (int I = 0; I != TotalNumParts; ++I) {
2677     LLT Ty = I < NumParts ? NarrowTy : LeftoverTy;
2678     Register PartDstReg = MRI.createGenericVirtualRegister(Ty);
2679     NewInsts.push_back(MIRBuilder.buildInstr(TargetOpcode::G_PHI)
2680                        .addDef(PartDstReg));
2681     if (I < NumParts)
2682       DstRegs.push_back(PartDstReg);
2683     else
2684       LeftoverDstRegs.push_back(PartDstReg);
2685   }
2686 
2687   MachineBasicBlock *MBB = MI.getParent();
2688   MIRBuilder.setInsertPt(*MBB, MBB->getFirstNonPHI());
2689   insertParts(DstReg, PhiTy, NarrowTy, DstRegs, LeftoverTy, LeftoverDstRegs);
2690 
2691   SmallVector<Register, 4> PartRegs, LeftoverRegs;
2692 
2693   // Insert code to extract the incoming values in each predecessor block.
2694   for (unsigned I = 1, E = MI.getNumOperands(); I != E; I += 2) {
2695     PartRegs.clear();
2696     LeftoverRegs.clear();
2697 
2698     Register SrcReg = MI.getOperand(I).getReg();
2699     MachineBasicBlock &OpMBB = *MI.getOperand(I + 1).getMBB();
2700     MIRBuilder.setInsertPt(OpMBB, OpMBB.getFirstTerminator());
2701 
2702     LLT Unused;
2703     if (!extractParts(SrcReg, PhiTy, NarrowTy, Unused, PartRegs,
2704                       LeftoverRegs))
2705       return UnableToLegalize;
2706 
2707     // Add the newly created operand splits to the existing instructions. The
2708     // odd-sized pieces are ordered after the requested NarrowTyArg sized
2709     // pieces.
2710     for (int J = 0; J != TotalNumParts; ++J) {
2711       MachineInstrBuilder MIB = NewInsts[J];
2712       MIB.addUse(J < NumParts ? PartRegs[J] : LeftoverRegs[J - NumParts]);
2713       MIB.addMBB(&OpMBB);
2714     }
2715   }
2716 
2717   MI.eraseFromParent();
2718   return Legalized;
2719 }
2720 
2721 LegalizerHelper::LegalizeResult
2722 LegalizerHelper::fewerElementsVectorUnmergeValues(MachineInstr &MI,
2723                                                   unsigned TypeIdx,
2724                                                   LLT NarrowTy) {
2725   if (TypeIdx != 1)
2726     return UnableToLegalize;
2727 
2728   const int NumDst = MI.getNumOperands() - 1;
2729   const Register SrcReg = MI.getOperand(NumDst).getReg();
2730   LLT SrcTy = MRI.getType(SrcReg);
2731 
2732   LLT DstTy = MRI.getType(MI.getOperand(0).getReg());
2733 
2734   // TODO: Create sequence of extracts.
2735   if (DstTy == NarrowTy)
2736     return UnableToLegalize;
2737 
2738   LLT GCDTy = getGCDType(SrcTy, NarrowTy);
2739   if (DstTy == GCDTy) {
2740     // This would just be a copy of the same unmerge.
2741     // TODO: Create extracts, pad with undef and create intermediate merges.
2742     return UnableToLegalize;
2743   }
2744 
2745   auto Unmerge = MIRBuilder.buildUnmerge(GCDTy, SrcReg);
2746   const int NumUnmerge = Unmerge->getNumOperands() - 1;
2747   const int PartsPerUnmerge = NumDst / NumUnmerge;
2748 
2749   for (int I = 0; I != NumUnmerge; ++I) {
2750     auto MIB = MIRBuilder.buildInstr(TargetOpcode::G_UNMERGE_VALUES);
2751 
2752     for (int J = 0; J != PartsPerUnmerge; ++J)
2753       MIB.addDef(MI.getOperand(I * PartsPerUnmerge + J).getReg());
2754     MIB.addUse(Unmerge.getReg(I));
2755   }
2756 
2757   MI.eraseFromParent();
2758   return Legalized;
2759 }
2760 
2761 LegalizerHelper::LegalizeResult
2762 LegalizerHelper::reduceLoadStoreWidth(MachineInstr &MI, unsigned TypeIdx,
2763                                       LLT NarrowTy) {
2764   // FIXME: Don't know how to handle secondary types yet.
2765   if (TypeIdx != 0)
2766     return UnableToLegalize;
2767 
2768   MachineMemOperand *MMO = *MI.memoperands_begin();
2769 
2770   // This implementation doesn't work for atomics. Give up instead of doing
2771   // something invalid.
2772   if (MMO->getOrdering() != AtomicOrdering::NotAtomic ||
2773       MMO->getFailureOrdering() != AtomicOrdering::NotAtomic)
2774     return UnableToLegalize;
2775 
2776   bool IsLoad = MI.getOpcode() == TargetOpcode::G_LOAD;
2777   Register ValReg = MI.getOperand(0).getReg();
2778   Register AddrReg = MI.getOperand(1).getReg();
2779   LLT ValTy = MRI.getType(ValReg);
2780 
2781   int NumParts = -1;
2782   int NumLeftover = -1;
2783   LLT LeftoverTy;
2784   SmallVector<Register, 8> NarrowRegs, NarrowLeftoverRegs;
2785   if (IsLoad) {
2786     std::tie(NumParts, NumLeftover) = getNarrowTypeBreakDown(ValTy, NarrowTy, LeftoverTy);
2787   } else {
2788     if (extractParts(ValReg, ValTy, NarrowTy, LeftoverTy, NarrowRegs,
2789                      NarrowLeftoverRegs)) {
2790       NumParts = NarrowRegs.size();
2791       NumLeftover = NarrowLeftoverRegs.size();
2792     }
2793   }
2794 
2795   if (NumParts == -1)
2796     return UnableToLegalize;
2797 
2798   const LLT OffsetTy = LLT::scalar(MRI.getType(AddrReg).getScalarSizeInBits());
2799 
2800   unsigned TotalSize = ValTy.getSizeInBits();
2801 
2802   // Split the load/store into PartTy sized pieces starting at Offset. If this
2803   // is a load, return the new registers in ValRegs. For a store, each elements
2804   // of ValRegs should be PartTy. Returns the next offset that needs to be
2805   // handled.
2806   auto splitTypePieces = [=](LLT PartTy, SmallVectorImpl<Register> &ValRegs,
2807                              unsigned Offset) -> unsigned {
2808     MachineFunction &MF = MIRBuilder.getMF();
2809     unsigned PartSize = PartTy.getSizeInBits();
2810     for (unsigned Idx = 0, E = NumParts; Idx != E && Offset < TotalSize;
2811          Offset += PartSize, ++Idx) {
2812       unsigned ByteSize = PartSize / 8;
2813       unsigned ByteOffset = Offset / 8;
2814       Register NewAddrReg;
2815 
2816       MIRBuilder.materializeGEP(NewAddrReg, AddrReg, OffsetTy, ByteOffset);
2817 
2818       MachineMemOperand *NewMMO =
2819         MF.getMachineMemOperand(MMO, ByteOffset, ByteSize);
2820 
2821       if (IsLoad) {
2822         Register Dst = MRI.createGenericVirtualRegister(PartTy);
2823         ValRegs.push_back(Dst);
2824         MIRBuilder.buildLoad(Dst, NewAddrReg, *NewMMO);
2825       } else {
2826         MIRBuilder.buildStore(ValRegs[Idx], NewAddrReg, *NewMMO);
2827       }
2828     }
2829 
2830     return Offset;
2831   };
2832 
2833   unsigned HandledOffset = splitTypePieces(NarrowTy, NarrowRegs, 0);
2834 
2835   // Handle the rest of the register if this isn't an even type breakdown.
2836   if (LeftoverTy.isValid())
2837     splitTypePieces(LeftoverTy, NarrowLeftoverRegs, HandledOffset);
2838 
2839   if (IsLoad) {
2840     insertParts(ValReg, ValTy, NarrowTy, NarrowRegs,
2841                 LeftoverTy, NarrowLeftoverRegs);
2842   }
2843 
2844   MI.eraseFromParent();
2845   return Legalized;
2846 }
2847 
2848 LegalizerHelper::LegalizeResult
2849 LegalizerHelper::fewerElementsVector(MachineInstr &MI, unsigned TypeIdx,
2850                                      LLT NarrowTy) {
2851   using namespace TargetOpcode;
2852 
2853   MIRBuilder.setInstr(MI);
2854   switch (MI.getOpcode()) {
2855   case G_IMPLICIT_DEF:
2856     return fewerElementsVectorImplicitDef(MI, TypeIdx, NarrowTy);
2857   case G_AND:
2858   case G_OR:
2859   case G_XOR:
2860   case G_ADD:
2861   case G_SUB:
2862   case G_MUL:
2863   case G_SMULH:
2864   case G_UMULH:
2865   case G_FADD:
2866   case G_FMUL:
2867   case G_FSUB:
2868   case G_FNEG:
2869   case G_FABS:
2870   case G_FCANONICALIZE:
2871   case G_FDIV:
2872   case G_FREM:
2873   case G_FMA:
2874   case G_FMAD:
2875   case G_FPOW:
2876   case G_FEXP:
2877   case G_FEXP2:
2878   case G_FLOG:
2879   case G_FLOG2:
2880   case G_FLOG10:
2881   case G_FNEARBYINT:
2882   case G_FCEIL:
2883   case G_FFLOOR:
2884   case G_FRINT:
2885   case G_INTRINSIC_ROUND:
2886   case G_INTRINSIC_TRUNC:
2887   case G_FCOS:
2888   case G_FSIN:
2889   case G_FSQRT:
2890   case G_BSWAP:
2891   case G_BITREVERSE:
2892   case G_SDIV:
2893   case G_SMIN:
2894   case G_SMAX:
2895   case G_UMIN:
2896   case G_UMAX:
2897   case G_FMINNUM:
2898   case G_FMAXNUM:
2899   case G_FMINNUM_IEEE:
2900   case G_FMAXNUM_IEEE:
2901   case G_FMINIMUM:
2902   case G_FMAXIMUM:
2903     return fewerElementsVectorBasic(MI, TypeIdx, NarrowTy);
2904   case G_SHL:
2905   case G_LSHR:
2906   case G_ASHR:
2907   case G_CTLZ:
2908   case G_CTLZ_ZERO_UNDEF:
2909   case G_CTTZ:
2910   case G_CTTZ_ZERO_UNDEF:
2911   case G_CTPOP:
2912   case G_FCOPYSIGN:
2913     return fewerElementsVectorMultiEltType(MI, TypeIdx, NarrowTy);
2914   case G_ZEXT:
2915   case G_SEXT:
2916   case G_ANYEXT:
2917   case G_FPEXT:
2918   case G_FPTRUNC:
2919   case G_SITOFP:
2920   case G_UITOFP:
2921   case G_FPTOSI:
2922   case G_FPTOUI:
2923   case G_INTTOPTR:
2924   case G_PTRTOINT:
2925   case G_ADDRSPACE_CAST:
2926     return fewerElementsVectorCasts(MI, TypeIdx, NarrowTy);
2927   case G_ICMP:
2928   case G_FCMP:
2929     return fewerElementsVectorCmp(MI, TypeIdx, NarrowTy);
2930   case G_SELECT:
2931     return fewerElementsVectorSelect(MI, TypeIdx, NarrowTy);
2932   case G_PHI:
2933     return fewerElementsVectorPhi(MI, TypeIdx, NarrowTy);
2934   case G_UNMERGE_VALUES:
2935     return fewerElementsVectorUnmergeValues(MI, TypeIdx, NarrowTy);
2936   case G_LOAD:
2937   case G_STORE:
2938     return reduceLoadStoreWidth(MI, TypeIdx, NarrowTy);
2939   default:
2940     return UnableToLegalize;
2941   }
2942 }
2943 
2944 LegalizerHelper::LegalizeResult
2945 LegalizerHelper::narrowScalarShiftByConstant(MachineInstr &MI, const APInt &Amt,
2946                                              const LLT HalfTy, const LLT AmtTy) {
2947 
2948   Register InL = MRI.createGenericVirtualRegister(HalfTy);
2949   Register InH = MRI.createGenericVirtualRegister(HalfTy);
2950   MIRBuilder.buildUnmerge({InL, InH}, MI.getOperand(1).getReg());
2951 
2952   if (Amt.isNullValue()) {
2953     MIRBuilder.buildMerge(MI.getOperand(0).getReg(), {InL, InH});
2954     MI.eraseFromParent();
2955     return Legalized;
2956   }
2957 
2958   LLT NVT = HalfTy;
2959   unsigned NVTBits = HalfTy.getSizeInBits();
2960   unsigned VTBits = 2 * NVTBits;
2961 
2962   SrcOp Lo(Register(0)), Hi(Register(0));
2963   if (MI.getOpcode() == TargetOpcode::G_SHL) {
2964     if (Amt.ugt(VTBits)) {
2965       Lo = Hi = MIRBuilder.buildConstant(NVT, 0);
2966     } else if (Amt.ugt(NVTBits)) {
2967       Lo = MIRBuilder.buildConstant(NVT, 0);
2968       Hi = MIRBuilder.buildShl(NVT, InL,
2969                                MIRBuilder.buildConstant(AmtTy, Amt - NVTBits));
2970     } else if (Amt == NVTBits) {
2971       Lo = MIRBuilder.buildConstant(NVT, 0);
2972       Hi = InL;
2973     } else {
2974       Lo = MIRBuilder.buildShl(NVT, InL, MIRBuilder.buildConstant(AmtTy, Amt));
2975       auto OrLHS =
2976           MIRBuilder.buildShl(NVT, InH, MIRBuilder.buildConstant(AmtTy, Amt));
2977       auto OrRHS = MIRBuilder.buildLShr(
2978           NVT, InL, MIRBuilder.buildConstant(AmtTy, -Amt + NVTBits));
2979       Hi = MIRBuilder.buildOr(NVT, OrLHS, OrRHS);
2980     }
2981   } else if (MI.getOpcode() == TargetOpcode::G_LSHR) {
2982     if (Amt.ugt(VTBits)) {
2983       Lo = Hi = MIRBuilder.buildConstant(NVT, 0);
2984     } else if (Amt.ugt(NVTBits)) {
2985       Lo = MIRBuilder.buildLShr(NVT, InH,
2986                                 MIRBuilder.buildConstant(AmtTy, Amt - NVTBits));
2987       Hi = MIRBuilder.buildConstant(NVT, 0);
2988     } else if (Amt == NVTBits) {
2989       Lo = InH;
2990       Hi = MIRBuilder.buildConstant(NVT, 0);
2991     } else {
2992       auto ShiftAmtConst = MIRBuilder.buildConstant(AmtTy, Amt);
2993 
2994       auto OrLHS = MIRBuilder.buildLShr(NVT, InL, ShiftAmtConst);
2995       auto OrRHS = MIRBuilder.buildShl(
2996           NVT, InH, MIRBuilder.buildConstant(AmtTy, -Amt + NVTBits));
2997 
2998       Lo = MIRBuilder.buildOr(NVT, OrLHS, OrRHS);
2999       Hi = MIRBuilder.buildLShr(NVT, InH, ShiftAmtConst);
3000     }
3001   } else {
3002     if (Amt.ugt(VTBits)) {
3003       Hi = Lo = MIRBuilder.buildAShr(
3004           NVT, InH, MIRBuilder.buildConstant(AmtTy, NVTBits - 1));
3005     } else if (Amt.ugt(NVTBits)) {
3006       Lo = MIRBuilder.buildAShr(NVT, InH,
3007                                 MIRBuilder.buildConstant(AmtTy, Amt - NVTBits));
3008       Hi = MIRBuilder.buildAShr(NVT, InH,
3009                                 MIRBuilder.buildConstant(AmtTy, NVTBits - 1));
3010     } else if (Amt == NVTBits) {
3011       Lo = InH;
3012       Hi = MIRBuilder.buildAShr(NVT, InH,
3013                                 MIRBuilder.buildConstant(AmtTy, NVTBits - 1));
3014     } else {
3015       auto ShiftAmtConst = MIRBuilder.buildConstant(AmtTy, Amt);
3016 
3017       auto OrLHS = MIRBuilder.buildLShr(NVT, InL, ShiftAmtConst);
3018       auto OrRHS = MIRBuilder.buildShl(
3019           NVT, InH, MIRBuilder.buildConstant(AmtTy, -Amt + NVTBits));
3020 
3021       Lo = MIRBuilder.buildOr(NVT, OrLHS, OrRHS);
3022       Hi = MIRBuilder.buildAShr(NVT, InH, ShiftAmtConst);
3023     }
3024   }
3025 
3026   MIRBuilder.buildMerge(MI.getOperand(0).getReg(), {Lo.getReg(), Hi.getReg()});
3027   MI.eraseFromParent();
3028 
3029   return Legalized;
3030 }
3031 
3032 // TODO: Optimize if constant shift amount.
3033 LegalizerHelper::LegalizeResult
3034 LegalizerHelper::narrowScalarShift(MachineInstr &MI, unsigned TypeIdx,
3035                                    LLT RequestedTy) {
3036   if (TypeIdx == 1) {
3037     Observer.changingInstr(MI);
3038     narrowScalarSrc(MI, RequestedTy, 2);
3039     Observer.changedInstr(MI);
3040     return Legalized;
3041   }
3042 
3043   Register DstReg = MI.getOperand(0).getReg();
3044   LLT DstTy = MRI.getType(DstReg);
3045   if (DstTy.isVector())
3046     return UnableToLegalize;
3047 
3048   Register Amt = MI.getOperand(2).getReg();
3049   LLT ShiftAmtTy = MRI.getType(Amt);
3050   const unsigned DstEltSize = DstTy.getScalarSizeInBits();
3051   if (DstEltSize % 2 != 0)
3052     return UnableToLegalize;
3053 
3054   // Ignore the input type. We can only go to exactly half the size of the
3055   // input. If that isn't small enough, the resulting pieces will be further
3056   // legalized.
3057   const unsigned NewBitSize = DstEltSize / 2;
3058   const LLT HalfTy = LLT::scalar(NewBitSize);
3059   const LLT CondTy = LLT::scalar(1);
3060 
3061   if (const MachineInstr *KShiftAmt =
3062           getOpcodeDef(TargetOpcode::G_CONSTANT, Amt, MRI)) {
3063     return narrowScalarShiftByConstant(
3064         MI, KShiftAmt->getOperand(1).getCImm()->getValue(), HalfTy, ShiftAmtTy);
3065   }
3066 
3067   // TODO: Expand with known bits.
3068 
3069   // Handle the fully general expansion by an unknown amount.
3070   auto NewBits = MIRBuilder.buildConstant(ShiftAmtTy, NewBitSize);
3071 
3072   Register InL = MRI.createGenericVirtualRegister(HalfTy);
3073   Register InH = MRI.createGenericVirtualRegister(HalfTy);
3074   MIRBuilder.buildUnmerge({InL, InH}, MI.getOperand(1).getReg());
3075 
3076   auto AmtExcess = MIRBuilder.buildSub(ShiftAmtTy, Amt, NewBits);
3077   auto AmtLack = MIRBuilder.buildSub(ShiftAmtTy, NewBits, Amt);
3078 
3079   auto Zero = MIRBuilder.buildConstant(ShiftAmtTy, 0);
3080   auto IsShort = MIRBuilder.buildICmp(ICmpInst::ICMP_ULT, CondTy, Amt, NewBits);
3081   auto IsZero = MIRBuilder.buildICmp(ICmpInst::ICMP_EQ, CondTy, Amt, Zero);
3082 
3083   Register ResultRegs[2];
3084   switch (MI.getOpcode()) {
3085   case TargetOpcode::G_SHL: {
3086     // Short: ShAmt < NewBitSize
3087     auto LoS = MIRBuilder.buildShl(HalfTy, InL, Amt);
3088 
3089     auto LoOr = MIRBuilder.buildLShr(HalfTy, InL, AmtLack);
3090     auto HiOr = MIRBuilder.buildShl(HalfTy, InH, Amt);
3091     auto HiS = MIRBuilder.buildOr(HalfTy, LoOr, HiOr);
3092 
3093     // Long: ShAmt >= NewBitSize
3094     auto LoL = MIRBuilder.buildConstant(HalfTy, 0);         // Lo part is zero.
3095     auto HiL = MIRBuilder.buildShl(HalfTy, InL, AmtExcess); // Hi from Lo part.
3096 
3097     auto Lo = MIRBuilder.buildSelect(HalfTy, IsShort, LoS, LoL);
3098     auto Hi = MIRBuilder.buildSelect(
3099         HalfTy, IsZero, InH, MIRBuilder.buildSelect(HalfTy, IsShort, HiS, HiL));
3100 
3101     ResultRegs[0] = Lo.getReg(0);
3102     ResultRegs[1] = Hi.getReg(0);
3103     break;
3104   }
3105   case TargetOpcode::G_LSHR:
3106   case TargetOpcode::G_ASHR: {
3107     // Short: ShAmt < NewBitSize
3108     auto HiS = MIRBuilder.buildInstr(MI.getOpcode(), {HalfTy}, {InH, Amt});
3109 
3110     auto LoOr = MIRBuilder.buildLShr(HalfTy, InL, Amt);
3111     auto HiOr = MIRBuilder.buildShl(HalfTy, InH, AmtLack);
3112     auto LoS = MIRBuilder.buildOr(HalfTy, LoOr, HiOr);
3113 
3114     // Long: ShAmt >= NewBitSize
3115     MachineInstrBuilder HiL;
3116     if (MI.getOpcode() == TargetOpcode::G_LSHR) {
3117       HiL = MIRBuilder.buildConstant(HalfTy, 0);            // Hi part is zero.
3118     } else {
3119       auto ShiftAmt = MIRBuilder.buildConstant(ShiftAmtTy, NewBitSize - 1);
3120       HiL = MIRBuilder.buildAShr(HalfTy, InH, ShiftAmt);    // Sign of Hi part.
3121     }
3122     auto LoL = MIRBuilder.buildInstr(MI.getOpcode(), {HalfTy},
3123                                      {InH, AmtExcess});     // Lo from Hi part.
3124 
3125     auto Lo = MIRBuilder.buildSelect(
3126         HalfTy, IsZero, InL, MIRBuilder.buildSelect(HalfTy, IsShort, LoS, LoL));
3127 
3128     auto Hi = MIRBuilder.buildSelect(HalfTy, IsShort, HiS, HiL);
3129 
3130     ResultRegs[0] = Lo.getReg(0);
3131     ResultRegs[1] = Hi.getReg(0);
3132     break;
3133   }
3134   default:
3135     llvm_unreachable("not a shift");
3136   }
3137 
3138   MIRBuilder.buildMerge(DstReg, ResultRegs);
3139   MI.eraseFromParent();
3140   return Legalized;
3141 }
3142 
3143 LegalizerHelper::LegalizeResult
3144 LegalizerHelper::moreElementsVectorPhi(MachineInstr &MI, unsigned TypeIdx,
3145                                        LLT MoreTy) {
3146   assert(TypeIdx == 0 && "Expecting only Idx 0");
3147 
3148   Observer.changingInstr(MI);
3149   for (unsigned I = 1, E = MI.getNumOperands(); I != E; I += 2) {
3150     MachineBasicBlock &OpMBB = *MI.getOperand(I + 1).getMBB();
3151     MIRBuilder.setInsertPt(OpMBB, OpMBB.getFirstTerminator());
3152     moreElementsVectorSrc(MI, MoreTy, I);
3153   }
3154 
3155   MachineBasicBlock &MBB = *MI.getParent();
3156   MIRBuilder.setInsertPt(MBB, --MBB.getFirstNonPHI());
3157   moreElementsVectorDst(MI, MoreTy, 0);
3158   Observer.changedInstr(MI);
3159   return Legalized;
3160 }
3161 
3162 LegalizerHelper::LegalizeResult
3163 LegalizerHelper::moreElementsVector(MachineInstr &MI, unsigned TypeIdx,
3164                                     LLT MoreTy) {
3165   MIRBuilder.setInstr(MI);
3166   unsigned Opc = MI.getOpcode();
3167   switch (Opc) {
3168   case TargetOpcode::G_IMPLICIT_DEF:
3169   case TargetOpcode::G_LOAD: {
3170     if (TypeIdx != 0)
3171       return UnableToLegalize;
3172     Observer.changingInstr(MI);
3173     moreElementsVectorDst(MI, MoreTy, 0);
3174     Observer.changedInstr(MI);
3175     return Legalized;
3176   }
3177   case TargetOpcode::G_STORE:
3178     if (TypeIdx != 0)
3179       return UnableToLegalize;
3180     Observer.changingInstr(MI);
3181     moreElementsVectorSrc(MI, MoreTy, 0);
3182     Observer.changedInstr(MI);
3183     return Legalized;
3184   case TargetOpcode::G_AND:
3185   case TargetOpcode::G_OR:
3186   case TargetOpcode::G_XOR:
3187   case TargetOpcode::G_SMIN:
3188   case TargetOpcode::G_SMAX:
3189   case TargetOpcode::G_UMIN:
3190   case TargetOpcode::G_UMAX: {
3191     Observer.changingInstr(MI);
3192     moreElementsVectorSrc(MI, MoreTy, 1);
3193     moreElementsVectorSrc(MI, MoreTy, 2);
3194     moreElementsVectorDst(MI, MoreTy, 0);
3195     Observer.changedInstr(MI);
3196     return Legalized;
3197   }
3198   case TargetOpcode::G_EXTRACT:
3199     if (TypeIdx != 1)
3200       return UnableToLegalize;
3201     Observer.changingInstr(MI);
3202     moreElementsVectorSrc(MI, MoreTy, 1);
3203     Observer.changedInstr(MI);
3204     return Legalized;
3205   case TargetOpcode::G_INSERT:
3206     if (TypeIdx != 0)
3207       return UnableToLegalize;
3208     Observer.changingInstr(MI);
3209     moreElementsVectorSrc(MI, MoreTy, 1);
3210     moreElementsVectorDst(MI, MoreTy, 0);
3211     Observer.changedInstr(MI);
3212     return Legalized;
3213   case TargetOpcode::G_SELECT:
3214     if (TypeIdx != 0)
3215       return UnableToLegalize;
3216     if (MRI.getType(MI.getOperand(1).getReg()).isVector())
3217       return UnableToLegalize;
3218 
3219     Observer.changingInstr(MI);
3220     moreElementsVectorSrc(MI, MoreTy, 2);
3221     moreElementsVectorSrc(MI, MoreTy, 3);
3222     moreElementsVectorDst(MI, MoreTy, 0);
3223     Observer.changedInstr(MI);
3224     return Legalized;
3225   case TargetOpcode::G_UNMERGE_VALUES: {
3226     if (TypeIdx != 1)
3227       return UnableToLegalize;
3228 
3229     LLT DstTy = MRI.getType(MI.getOperand(0).getReg());
3230     int NumDst = MI.getNumOperands() - 1;
3231     moreElementsVectorSrc(MI, MoreTy, NumDst);
3232 
3233     auto MIB = MIRBuilder.buildInstr(TargetOpcode::G_UNMERGE_VALUES);
3234     for (int I = 0; I != NumDst; ++I)
3235       MIB.addDef(MI.getOperand(I).getReg());
3236 
3237     int NewNumDst = MoreTy.getSizeInBits() / DstTy.getSizeInBits();
3238     for (int I = NumDst; I != NewNumDst; ++I)
3239       MIB.addDef(MRI.createGenericVirtualRegister(DstTy));
3240 
3241     MIB.addUse(MI.getOperand(NumDst).getReg());
3242     MI.eraseFromParent();
3243     return Legalized;
3244   }
3245   case TargetOpcode::G_PHI:
3246     return moreElementsVectorPhi(MI, TypeIdx, MoreTy);
3247   default:
3248     return UnableToLegalize;
3249   }
3250 }
3251 
3252 void LegalizerHelper::multiplyRegisters(SmallVectorImpl<Register> &DstRegs,
3253                                         ArrayRef<Register> Src1Regs,
3254                                         ArrayRef<Register> Src2Regs,
3255                                         LLT NarrowTy) {
3256   MachineIRBuilder &B = MIRBuilder;
3257   unsigned SrcParts = Src1Regs.size();
3258   unsigned DstParts = DstRegs.size();
3259 
3260   unsigned DstIdx = 0; // Low bits of the result.
3261   Register FactorSum =
3262       B.buildMul(NarrowTy, Src1Regs[DstIdx], Src2Regs[DstIdx]).getReg(0);
3263   DstRegs[DstIdx] = FactorSum;
3264 
3265   unsigned CarrySumPrevDstIdx;
3266   SmallVector<Register, 4> Factors;
3267 
3268   for (DstIdx = 1; DstIdx < DstParts; DstIdx++) {
3269     // Collect low parts of muls for DstIdx.
3270     for (unsigned i = DstIdx + 1 < SrcParts ? 0 : DstIdx - SrcParts + 1;
3271          i <= std::min(DstIdx, SrcParts - 1); ++i) {
3272       MachineInstrBuilder Mul =
3273           B.buildMul(NarrowTy, Src1Regs[DstIdx - i], Src2Regs[i]);
3274       Factors.push_back(Mul.getReg(0));
3275     }
3276     // Collect high parts of muls from previous DstIdx.
3277     for (unsigned i = DstIdx < SrcParts ? 0 : DstIdx - SrcParts;
3278          i <= std::min(DstIdx - 1, SrcParts - 1); ++i) {
3279       MachineInstrBuilder Umulh =
3280           B.buildUMulH(NarrowTy, Src1Regs[DstIdx - 1 - i], Src2Regs[i]);
3281       Factors.push_back(Umulh.getReg(0));
3282     }
3283     // Add CarrySum from additons calculated for previous DstIdx.
3284     if (DstIdx != 1) {
3285       Factors.push_back(CarrySumPrevDstIdx);
3286     }
3287 
3288     Register CarrySum;
3289     // Add all factors and accumulate all carries into CarrySum.
3290     if (DstIdx != DstParts - 1) {
3291       MachineInstrBuilder Uaddo =
3292           B.buildUAddo(NarrowTy, LLT::scalar(1), Factors[0], Factors[1]);
3293       FactorSum = Uaddo.getReg(0);
3294       CarrySum = B.buildZExt(NarrowTy, Uaddo.getReg(1)).getReg(0);
3295       for (unsigned i = 2; i < Factors.size(); ++i) {
3296         MachineInstrBuilder Uaddo =
3297             B.buildUAddo(NarrowTy, LLT::scalar(1), FactorSum, Factors[i]);
3298         FactorSum = Uaddo.getReg(0);
3299         MachineInstrBuilder Carry = B.buildZExt(NarrowTy, Uaddo.getReg(1));
3300         CarrySum = B.buildAdd(NarrowTy, CarrySum, Carry).getReg(0);
3301       }
3302     } else {
3303       // Since value for the next index is not calculated, neither is CarrySum.
3304       FactorSum = B.buildAdd(NarrowTy, Factors[0], Factors[1]).getReg(0);
3305       for (unsigned i = 2; i < Factors.size(); ++i)
3306         FactorSum = B.buildAdd(NarrowTy, FactorSum, Factors[i]).getReg(0);
3307     }
3308 
3309     CarrySumPrevDstIdx = CarrySum;
3310     DstRegs[DstIdx] = FactorSum;
3311     Factors.clear();
3312   }
3313 }
3314 
3315 LegalizerHelper::LegalizeResult
3316 LegalizerHelper::narrowScalarMul(MachineInstr &MI, LLT NarrowTy) {
3317   Register DstReg = MI.getOperand(0).getReg();
3318   Register Src1 = MI.getOperand(1).getReg();
3319   Register Src2 = MI.getOperand(2).getReg();
3320 
3321   LLT Ty = MRI.getType(DstReg);
3322   if (Ty.isVector())
3323     return UnableToLegalize;
3324 
3325   unsigned SrcSize = MRI.getType(Src1).getSizeInBits();
3326   unsigned DstSize = Ty.getSizeInBits();
3327   unsigned NarrowSize = NarrowTy.getSizeInBits();
3328   if (DstSize % NarrowSize != 0 || SrcSize % NarrowSize != 0)
3329     return UnableToLegalize;
3330 
3331   unsigned NumDstParts = DstSize / NarrowSize;
3332   unsigned NumSrcParts = SrcSize / NarrowSize;
3333   bool IsMulHigh = MI.getOpcode() == TargetOpcode::G_UMULH;
3334   unsigned DstTmpParts = NumDstParts * (IsMulHigh ? 2 : 1);
3335 
3336   SmallVector<Register, 2> Src1Parts, Src2Parts, DstTmpRegs;
3337   extractParts(Src1, NarrowTy, NumSrcParts, Src1Parts);
3338   extractParts(Src2, NarrowTy, NumSrcParts, Src2Parts);
3339   DstTmpRegs.resize(DstTmpParts);
3340   multiplyRegisters(DstTmpRegs, Src1Parts, Src2Parts, NarrowTy);
3341 
3342   // Take only high half of registers if this is high mul.
3343   ArrayRef<Register> DstRegs(
3344       IsMulHigh ? &DstTmpRegs[DstTmpParts / 2] : &DstTmpRegs[0], NumDstParts);
3345   MIRBuilder.buildMerge(DstReg, DstRegs);
3346   MI.eraseFromParent();
3347   return Legalized;
3348 }
3349 
3350 LegalizerHelper::LegalizeResult
3351 LegalizerHelper::narrowScalarExtract(MachineInstr &MI, unsigned TypeIdx,
3352                                      LLT NarrowTy) {
3353   if (TypeIdx != 1)
3354     return UnableToLegalize;
3355 
3356   uint64_t NarrowSize = NarrowTy.getSizeInBits();
3357 
3358   int64_t SizeOp1 = MRI.getType(MI.getOperand(1).getReg()).getSizeInBits();
3359   // FIXME: add support for when SizeOp1 isn't an exact multiple of
3360   // NarrowSize.
3361   if (SizeOp1 % NarrowSize != 0)
3362     return UnableToLegalize;
3363   int NumParts = SizeOp1 / NarrowSize;
3364 
3365   SmallVector<Register, 2> SrcRegs, DstRegs;
3366   SmallVector<uint64_t, 2> Indexes;
3367   extractParts(MI.getOperand(1).getReg(), NarrowTy, NumParts, SrcRegs);
3368 
3369   Register OpReg = MI.getOperand(0).getReg();
3370   uint64_t OpStart = MI.getOperand(2).getImm();
3371   uint64_t OpSize = MRI.getType(OpReg).getSizeInBits();
3372   for (int i = 0; i < NumParts; ++i) {
3373     unsigned SrcStart = i * NarrowSize;
3374 
3375     if (SrcStart + NarrowSize <= OpStart || SrcStart >= OpStart + OpSize) {
3376       // No part of the extract uses this subregister, ignore it.
3377       continue;
3378     } else if (SrcStart == OpStart && NarrowTy == MRI.getType(OpReg)) {
3379       // The entire subregister is extracted, forward the value.
3380       DstRegs.push_back(SrcRegs[i]);
3381       continue;
3382     }
3383 
3384     // OpSegStart is where this destination segment would start in OpReg if it
3385     // extended infinitely in both directions.
3386     int64_t ExtractOffset;
3387     uint64_t SegSize;
3388     if (OpStart < SrcStart) {
3389       ExtractOffset = 0;
3390       SegSize = std::min(NarrowSize, OpStart + OpSize - SrcStart);
3391     } else {
3392       ExtractOffset = OpStart - SrcStart;
3393       SegSize = std::min(SrcStart + NarrowSize - OpStart, OpSize);
3394     }
3395 
3396     Register SegReg = SrcRegs[i];
3397     if (ExtractOffset != 0 || SegSize != NarrowSize) {
3398       // A genuine extract is needed.
3399       SegReg = MRI.createGenericVirtualRegister(LLT::scalar(SegSize));
3400       MIRBuilder.buildExtract(SegReg, SrcRegs[i], ExtractOffset);
3401     }
3402 
3403     DstRegs.push_back(SegReg);
3404   }
3405 
3406   Register DstReg = MI.getOperand(0).getReg();
3407   if(MRI.getType(DstReg).isVector())
3408     MIRBuilder.buildBuildVector(DstReg, DstRegs);
3409   else
3410     MIRBuilder.buildMerge(DstReg, DstRegs);
3411   MI.eraseFromParent();
3412   return Legalized;
3413 }
3414 
3415 LegalizerHelper::LegalizeResult
3416 LegalizerHelper::narrowScalarInsert(MachineInstr &MI, unsigned TypeIdx,
3417                                     LLT NarrowTy) {
3418   // FIXME: Don't know how to handle secondary types yet.
3419   if (TypeIdx != 0)
3420     return UnableToLegalize;
3421 
3422   uint64_t SizeOp0 = MRI.getType(MI.getOperand(0).getReg()).getSizeInBits();
3423   uint64_t NarrowSize = NarrowTy.getSizeInBits();
3424 
3425   // FIXME: add support for when SizeOp0 isn't an exact multiple of
3426   // NarrowSize.
3427   if (SizeOp0 % NarrowSize != 0)
3428     return UnableToLegalize;
3429 
3430   int NumParts = SizeOp0 / NarrowSize;
3431 
3432   SmallVector<Register, 2> SrcRegs, DstRegs;
3433   SmallVector<uint64_t, 2> Indexes;
3434   extractParts(MI.getOperand(1).getReg(), NarrowTy, NumParts, SrcRegs);
3435 
3436   Register OpReg = MI.getOperand(2).getReg();
3437   uint64_t OpStart = MI.getOperand(3).getImm();
3438   uint64_t OpSize = MRI.getType(OpReg).getSizeInBits();
3439   for (int i = 0; i < NumParts; ++i) {
3440     unsigned DstStart = i * NarrowSize;
3441 
3442     if (DstStart + NarrowSize <= OpStart || DstStart >= OpStart + OpSize) {
3443       // No part of the insert affects this subregister, forward the original.
3444       DstRegs.push_back(SrcRegs[i]);
3445       continue;
3446     } else if (DstStart == OpStart && NarrowTy == MRI.getType(OpReg)) {
3447       // The entire subregister is defined by this insert, forward the new
3448       // value.
3449       DstRegs.push_back(OpReg);
3450       continue;
3451     }
3452 
3453     // OpSegStart is where this destination segment would start in OpReg if it
3454     // extended infinitely in both directions.
3455     int64_t ExtractOffset, InsertOffset;
3456     uint64_t SegSize;
3457     if (OpStart < DstStart) {
3458       InsertOffset = 0;
3459       ExtractOffset = DstStart - OpStart;
3460       SegSize = std::min(NarrowSize, OpStart + OpSize - DstStart);
3461     } else {
3462       InsertOffset = OpStart - DstStart;
3463       ExtractOffset = 0;
3464       SegSize =
3465         std::min(NarrowSize - InsertOffset, OpStart + OpSize - DstStart);
3466     }
3467 
3468     Register SegReg = OpReg;
3469     if (ExtractOffset != 0 || SegSize != OpSize) {
3470       // A genuine extract is needed.
3471       SegReg = MRI.createGenericVirtualRegister(LLT::scalar(SegSize));
3472       MIRBuilder.buildExtract(SegReg, OpReg, ExtractOffset);
3473     }
3474 
3475     Register DstReg = MRI.createGenericVirtualRegister(NarrowTy);
3476     MIRBuilder.buildInsert(DstReg, SrcRegs[i], SegReg, InsertOffset);
3477     DstRegs.push_back(DstReg);
3478   }
3479 
3480   assert(DstRegs.size() == (unsigned)NumParts && "not all parts covered");
3481   Register DstReg = MI.getOperand(0).getReg();
3482   if(MRI.getType(DstReg).isVector())
3483     MIRBuilder.buildBuildVector(DstReg, DstRegs);
3484   else
3485     MIRBuilder.buildMerge(DstReg, DstRegs);
3486   MI.eraseFromParent();
3487   return Legalized;
3488 }
3489 
3490 LegalizerHelper::LegalizeResult
3491 LegalizerHelper::narrowScalarBasic(MachineInstr &MI, unsigned TypeIdx,
3492                                    LLT NarrowTy) {
3493   Register DstReg = MI.getOperand(0).getReg();
3494   LLT DstTy = MRI.getType(DstReg);
3495 
3496   assert(MI.getNumOperands() == 3 && TypeIdx == 0);
3497 
3498   SmallVector<Register, 4> DstRegs, DstLeftoverRegs;
3499   SmallVector<Register, 4> Src0Regs, Src0LeftoverRegs;
3500   SmallVector<Register, 4> Src1Regs, Src1LeftoverRegs;
3501   LLT LeftoverTy;
3502   if (!extractParts(MI.getOperand(1).getReg(), DstTy, NarrowTy, LeftoverTy,
3503                     Src0Regs, Src0LeftoverRegs))
3504     return UnableToLegalize;
3505 
3506   LLT Unused;
3507   if (!extractParts(MI.getOperand(2).getReg(), DstTy, NarrowTy, Unused,
3508                     Src1Regs, Src1LeftoverRegs))
3509     llvm_unreachable("inconsistent extractParts result");
3510 
3511   for (unsigned I = 0, E = Src1Regs.size(); I != E; ++I) {
3512     auto Inst = MIRBuilder.buildInstr(MI.getOpcode(), {NarrowTy},
3513                                         {Src0Regs[I], Src1Regs[I]});
3514     DstRegs.push_back(Inst->getOperand(0).getReg());
3515   }
3516 
3517   for (unsigned I = 0, E = Src1LeftoverRegs.size(); I != E; ++I) {
3518     auto Inst = MIRBuilder.buildInstr(
3519       MI.getOpcode(),
3520       {LeftoverTy}, {Src0LeftoverRegs[I], Src1LeftoverRegs[I]});
3521     DstLeftoverRegs.push_back(Inst->getOperand(0).getReg());
3522   }
3523 
3524   insertParts(DstReg, DstTy, NarrowTy, DstRegs,
3525               LeftoverTy, DstLeftoverRegs);
3526 
3527   MI.eraseFromParent();
3528   return Legalized;
3529 }
3530 
3531 LegalizerHelper::LegalizeResult
3532 LegalizerHelper::narrowScalarSelect(MachineInstr &MI, unsigned TypeIdx,
3533                                     LLT NarrowTy) {
3534   if (TypeIdx != 0)
3535     return UnableToLegalize;
3536 
3537   Register CondReg = MI.getOperand(1).getReg();
3538   LLT CondTy = MRI.getType(CondReg);
3539   if (CondTy.isVector()) // TODO: Handle vselect
3540     return UnableToLegalize;
3541 
3542   Register DstReg = MI.getOperand(0).getReg();
3543   LLT DstTy = MRI.getType(DstReg);
3544 
3545   SmallVector<Register, 4> DstRegs, DstLeftoverRegs;
3546   SmallVector<Register, 4> Src1Regs, Src1LeftoverRegs;
3547   SmallVector<Register, 4> Src2Regs, Src2LeftoverRegs;
3548   LLT LeftoverTy;
3549   if (!extractParts(MI.getOperand(2).getReg(), DstTy, NarrowTy, LeftoverTy,
3550                     Src1Regs, Src1LeftoverRegs))
3551     return UnableToLegalize;
3552 
3553   LLT Unused;
3554   if (!extractParts(MI.getOperand(3).getReg(), DstTy, NarrowTy, Unused,
3555                     Src2Regs, Src2LeftoverRegs))
3556     llvm_unreachable("inconsistent extractParts result");
3557 
3558   for (unsigned I = 0, E = Src1Regs.size(); I != E; ++I) {
3559     auto Select = MIRBuilder.buildSelect(NarrowTy,
3560                                          CondReg, Src1Regs[I], Src2Regs[I]);
3561     DstRegs.push_back(Select->getOperand(0).getReg());
3562   }
3563 
3564   for (unsigned I = 0, E = Src1LeftoverRegs.size(); I != E; ++I) {
3565     auto Select = MIRBuilder.buildSelect(
3566       LeftoverTy, CondReg, Src1LeftoverRegs[I], Src2LeftoverRegs[I]);
3567     DstLeftoverRegs.push_back(Select->getOperand(0).getReg());
3568   }
3569 
3570   insertParts(DstReg, DstTy, NarrowTy, DstRegs,
3571               LeftoverTy, DstLeftoverRegs);
3572 
3573   MI.eraseFromParent();
3574   return Legalized;
3575 }
3576 
3577 LegalizerHelper::LegalizeResult
3578 LegalizerHelper::lowerBitCount(MachineInstr &MI, unsigned TypeIdx, LLT Ty) {
3579   unsigned Opc = MI.getOpcode();
3580   auto &TII = *MI.getMF()->getSubtarget().getInstrInfo();
3581   auto isSupported = [this](const LegalityQuery &Q) {
3582     auto QAction = LI.getAction(Q).Action;
3583     return QAction == Legal || QAction == Libcall || QAction == Custom;
3584   };
3585   switch (Opc) {
3586   default:
3587     return UnableToLegalize;
3588   case TargetOpcode::G_CTLZ_ZERO_UNDEF: {
3589     // This trivially expands to CTLZ.
3590     Observer.changingInstr(MI);
3591     MI.setDesc(TII.get(TargetOpcode::G_CTLZ));
3592     Observer.changedInstr(MI);
3593     return Legalized;
3594   }
3595   case TargetOpcode::G_CTLZ: {
3596     Register SrcReg = MI.getOperand(1).getReg();
3597     unsigned Len = Ty.getSizeInBits();
3598     if (isSupported({TargetOpcode::G_CTLZ_ZERO_UNDEF, {Ty, Ty}})) {
3599       // If CTLZ_ZERO_UNDEF is supported, emit that and a select for zero.
3600       auto MIBCtlzZU = MIRBuilder.buildInstr(TargetOpcode::G_CTLZ_ZERO_UNDEF,
3601                                              {Ty}, {SrcReg});
3602       auto MIBZero = MIRBuilder.buildConstant(Ty, 0);
3603       auto MIBLen = MIRBuilder.buildConstant(Ty, Len);
3604       auto MIBICmp = MIRBuilder.buildICmp(CmpInst::ICMP_EQ, LLT::scalar(1),
3605                                           SrcReg, MIBZero);
3606       MIRBuilder.buildSelect(MI.getOperand(0).getReg(), MIBICmp, MIBLen,
3607                              MIBCtlzZU);
3608       MI.eraseFromParent();
3609       return Legalized;
3610     }
3611     // for now, we do this:
3612     // NewLen = NextPowerOf2(Len);
3613     // x = x | (x >> 1);
3614     // x = x | (x >> 2);
3615     // ...
3616     // x = x | (x >>16);
3617     // x = x | (x >>32); // for 64-bit input
3618     // Upto NewLen/2
3619     // return Len - popcount(x);
3620     //
3621     // Ref: "Hacker's Delight" by Henry Warren
3622     Register Op = SrcReg;
3623     unsigned NewLen = PowerOf2Ceil(Len);
3624     for (unsigned i = 0; (1U << i) <= (NewLen / 2); ++i) {
3625       auto MIBShiftAmt = MIRBuilder.buildConstant(Ty, 1ULL << i);
3626       auto MIBOp = MIRBuilder.buildInstr(
3627           TargetOpcode::G_OR, {Ty},
3628           {Op, MIRBuilder.buildInstr(TargetOpcode::G_LSHR, {Ty},
3629                                      {Op, MIBShiftAmt})});
3630       Op = MIBOp->getOperand(0).getReg();
3631     }
3632     auto MIBPop = MIRBuilder.buildInstr(TargetOpcode::G_CTPOP, {Ty}, {Op});
3633     MIRBuilder.buildInstr(TargetOpcode::G_SUB, {MI.getOperand(0).getReg()},
3634                           {MIRBuilder.buildConstant(Ty, Len), MIBPop});
3635     MI.eraseFromParent();
3636     return Legalized;
3637   }
3638   case TargetOpcode::G_CTTZ_ZERO_UNDEF: {
3639     // This trivially expands to CTTZ.
3640     Observer.changingInstr(MI);
3641     MI.setDesc(TII.get(TargetOpcode::G_CTTZ));
3642     Observer.changedInstr(MI);
3643     return Legalized;
3644   }
3645   case TargetOpcode::G_CTTZ: {
3646     Register SrcReg = MI.getOperand(1).getReg();
3647     unsigned Len = Ty.getSizeInBits();
3648     if (isSupported({TargetOpcode::G_CTTZ_ZERO_UNDEF, {Ty, Ty}})) {
3649       // If CTTZ_ZERO_UNDEF is legal or custom, emit that and a select with
3650       // zero.
3651       auto MIBCttzZU = MIRBuilder.buildInstr(TargetOpcode::G_CTTZ_ZERO_UNDEF,
3652                                              {Ty}, {SrcReg});
3653       auto MIBZero = MIRBuilder.buildConstant(Ty, 0);
3654       auto MIBLen = MIRBuilder.buildConstant(Ty, Len);
3655       auto MIBICmp = MIRBuilder.buildICmp(CmpInst::ICMP_EQ, LLT::scalar(1),
3656                                           SrcReg, MIBZero);
3657       MIRBuilder.buildSelect(MI.getOperand(0).getReg(), MIBICmp, MIBLen,
3658                              MIBCttzZU);
3659       MI.eraseFromParent();
3660       return Legalized;
3661     }
3662     // for now, we use: { return popcount(~x & (x - 1)); }
3663     // unless the target has ctlz but not ctpop, in which case we use:
3664     // { return 32 - nlz(~x & (x-1)); }
3665     // Ref: "Hacker's Delight" by Henry Warren
3666     auto MIBCstNeg1 = MIRBuilder.buildConstant(Ty, -1);
3667     auto MIBNot =
3668         MIRBuilder.buildInstr(TargetOpcode::G_XOR, {Ty}, {SrcReg, MIBCstNeg1});
3669     auto MIBTmp = MIRBuilder.buildInstr(
3670         TargetOpcode::G_AND, {Ty},
3671         {MIBNot, MIRBuilder.buildInstr(TargetOpcode::G_ADD, {Ty},
3672                                        {SrcReg, MIBCstNeg1})});
3673     if (!isSupported({TargetOpcode::G_CTPOP, {Ty, Ty}}) &&
3674         isSupported({TargetOpcode::G_CTLZ, {Ty, Ty}})) {
3675       auto MIBCstLen = MIRBuilder.buildConstant(Ty, Len);
3676       MIRBuilder.buildInstr(
3677           TargetOpcode::G_SUB, {MI.getOperand(0).getReg()},
3678           {MIBCstLen,
3679            MIRBuilder.buildInstr(TargetOpcode::G_CTLZ, {Ty}, {MIBTmp})});
3680       MI.eraseFromParent();
3681       return Legalized;
3682     }
3683     MI.setDesc(TII.get(TargetOpcode::G_CTPOP));
3684     MI.getOperand(1).setReg(MIBTmp->getOperand(0).getReg());
3685     return Legalized;
3686   }
3687   }
3688 }
3689 
3690 // Expand s32 = G_UITOFP s64 using bit operations to an IEEE float
3691 // representation.
3692 LegalizerHelper::LegalizeResult
3693 LegalizerHelper::lowerU64ToF32BitOps(MachineInstr &MI) {
3694   Register Dst = MI.getOperand(0).getReg();
3695   Register Src = MI.getOperand(1).getReg();
3696   const LLT S64 = LLT::scalar(64);
3697   const LLT S32 = LLT::scalar(32);
3698   const LLT S1 = LLT::scalar(1);
3699 
3700   assert(MRI.getType(Src) == S64 && MRI.getType(Dst) == S32);
3701 
3702   // unsigned cul2f(ulong u) {
3703   //   uint lz = clz(u);
3704   //   uint e = (u != 0) ? 127U + 63U - lz : 0;
3705   //   u = (u << lz) & 0x7fffffffffffffffUL;
3706   //   ulong t = u & 0xffffffffffUL;
3707   //   uint v = (e << 23) | (uint)(u >> 40);
3708   //   uint r = t > 0x8000000000UL ? 1U : (t == 0x8000000000UL ? v & 1U : 0U);
3709   //   return as_float(v + r);
3710   // }
3711 
3712   auto Zero32 = MIRBuilder.buildConstant(S32, 0);
3713   auto Zero64 = MIRBuilder.buildConstant(S64, 0);
3714 
3715   auto LZ = MIRBuilder.buildCTLZ_ZERO_UNDEF(S32, Src);
3716 
3717   auto K = MIRBuilder.buildConstant(S32, 127U + 63U);
3718   auto Sub = MIRBuilder.buildSub(S32, K, LZ);
3719 
3720   auto NotZero = MIRBuilder.buildICmp(CmpInst::ICMP_NE, S1, Src, Zero64);
3721   auto E = MIRBuilder.buildSelect(S32, NotZero, Sub, Zero32);
3722 
3723   auto Mask0 = MIRBuilder.buildConstant(S64, (-1ULL) >> 1);
3724   auto ShlLZ = MIRBuilder.buildShl(S64, Src, LZ);
3725 
3726   auto U = MIRBuilder.buildAnd(S64, ShlLZ, Mask0);
3727 
3728   auto Mask1 = MIRBuilder.buildConstant(S64, 0xffffffffffULL);
3729   auto T = MIRBuilder.buildAnd(S64, U, Mask1);
3730 
3731   auto UShl = MIRBuilder.buildLShr(S64, U, MIRBuilder.buildConstant(S64, 40));
3732   auto ShlE = MIRBuilder.buildShl(S32, E, MIRBuilder.buildConstant(S32, 23));
3733   auto V = MIRBuilder.buildOr(S32, ShlE, MIRBuilder.buildTrunc(S32, UShl));
3734 
3735   auto C = MIRBuilder.buildConstant(S64, 0x8000000000ULL);
3736   auto RCmp = MIRBuilder.buildICmp(CmpInst::ICMP_UGT, S1, T, C);
3737   auto TCmp = MIRBuilder.buildICmp(CmpInst::ICMP_EQ, S1, T, C);
3738   auto One = MIRBuilder.buildConstant(S32, 1);
3739 
3740   auto VTrunc1 = MIRBuilder.buildAnd(S32, V, One);
3741   auto Select0 = MIRBuilder.buildSelect(S32, TCmp, VTrunc1, Zero32);
3742   auto R = MIRBuilder.buildSelect(S32, RCmp, One, Select0);
3743   MIRBuilder.buildAdd(Dst, V, R);
3744 
3745   return Legalized;
3746 }
3747 
3748 LegalizerHelper::LegalizeResult
3749 LegalizerHelper::lowerUITOFP(MachineInstr &MI, unsigned TypeIdx, LLT Ty) {
3750   Register Dst = MI.getOperand(0).getReg();
3751   Register Src = MI.getOperand(1).getReg();
3752   LLT DstTy = MRI.getType(Dst);
3753   LLT SrcTy = MRI.getType(Src);
3754 
3755   if (SrcTy != LLT::scalar(64))
3756     return UnableToLegalize;
3757 
3758   if (DstTy == LLT::scalar(32)) {
3759     // TODO: SelectionDAG has several alternative expansions to port which may
3760     // be more reasonble depending on the available instructions. If a target
3761     // has sitofp, does not have CTLZ, or can efficiently use f64 as an
3762     // intermediate type, this is probably worse.
3763     return lowerU64ToF32BitOps(MI);
3764   }
3765 
3766   return UnableToLegalize;
3767 }
3768 
3769 LegalizerHelper::LegalizeResult
3770 LegalizerHelper::lowerSITOFP(MachineInstr &MI, unsigned TypeIdx, LLT Ty) {
3771   Register Dst = MI.getOperand(0).getReg();
3772   Register Src = MI.getOperand(1).getReg();
3773   LLT DstTy = MRI.getType(Dst);
3774   LLT SrcTy = MRI.getType(Src);
3775 
3776   const LLT S64 = LLT::scalar(64);
3777   const LLT S32 = LLT::scalar(32);
3778   const LLT S1 = LLT::scalar(1);
3779 
3780   if (SrcTy != S64)
3781     return UnableToLegalize;
3782 
3783   if (DstTy == S32) {
3784     // signed cl2f(long l) {
3785     //   long s = l >> 63;
3786     //   float r = cul2f((l + s) ^ s);
3787     //   return s ? -r : r;
3788     // }
3789     Register L = Src;
3790     auto SignBit = MIRBuilder.buildConstant(S64, 63);
3791     auto S = MIRBuilder.buildAShr(S64, L, SignBit);
3792 
3793     auto LPlusS = MIRBuilder.buildAdd(S64, L, S);
3794     auto Xor = MIRBuilder.buildXor(S64, LPlusS, S);
3795     auto R = MIRBuilder.buildUITOFP(S32, Xor);
3796 
3797     auto RNeg = MIRBuilder.buildFNeg(S32, R);
3798     auto SignNotZero = MIRBuilder.buildICmp(CmpInst::ICMP_NE, S1, S,
3799                                             MIRBuilder.buildConstant(S64, 0));
3800     MIRBuilder.buildSelect(Dst, SignNotZero, RNeg, R);
3801     return Legalized;
3802   }
3803 
3804   return UnableToLegalize;
3805 }
3806 
3807 LegalizerHelper::LegalizeResult
3808 LegalizerHelper::lowerFPTOUI(MachineInstr &MI, unsigned TypeIdx, LLT Ty) {
3809   Register Dst = MI.getOperand(0).getReg();
3810   Register Src = MI.getOperand(1).getReg();
3811   LLT DstTy = MRI.getType(Dst);
3812   LLT SrcTy = MRI.getType(Src);
3813   const LLT S64 = LLT::scalar(64);
3814   const LLT S32 = LLT::scalar(32);
3815 
3816   if (SrcTy != S64 && SrcTy != S32)
3817     return UnableToLegalize;
3818   if (DstTy != S32 && DstTy != S64)
3819     return UnableToLegalize;
3820 
3821   // FPTOSI gives same result as FPTOUI for positive signed integers.
3822   // FPTOUI needs to deal with fp values that convert to unsigned integers
3823   // greater or equal to 2^31 for float or 2^63 for double. For brevity 2^Exp.
3824 
3825   APInt TwoPExpInt = APInt::getSignMask(DstTy.getSizeInBits());
3826   APFloat TwoPExpFP(SrcTy.getSizeInBits() == 32 ? APFloat::IEEEsingle()
3827                                                 : APFloat::IEEEdouble(),
3828                     APInt::getNullValue(SrcTy.getSizeInBits()));
3829   TwoPExpFP.convertFromAPInt(TwoPExpInt, false, APFloat::rmNearestTiesToEven);
3830 
3831   MachineInstrBuilder FPTOSI = MIRBuilder.buildFPTOSI(DstTy, Src);
3832 
3833   MachineInstrBuilder Threshold = MIRBuilder.buildFConstant(SrcTy, TwoPExpFP);
3834   // For fp Value greater or equal to Threshold(2^Exp), we use FPTOSI on
3835   // (Value - 2^Exp) and add 2^Exp by setting highest bit in result to 1.
3836   MachineInstrBuilder FSub = MIRBuilder.buildFSub(SrcTy, Src, Threshold);
3837   MachineInstrBuilder ResLowBits = MIRBuilder.buildFPTOSI(DstTy, FSub);
3838   MachineInstrBuilder ResHighBit = MIRBuilder.buildConstant(DstTy, TwoPExpInt);
3839   MachineInstrBuilder Res = MIRBuilder.buildXor(DstTy, ResLowBits, ResHighBit);
3840 
3841   MachineInstrBuilder FCMP =
3842       MIRBuilder.buildFCmp(CmpInst::FCMP_ULT, DstTy, Src, Threshold);
3843   MIRBuilder.buildSelect(Dst, FCMP, FPTOSI, Res);
3844 
3845   MI.eraseFromParent();
3846   return Legalized;
3847 }
3848 
3849 static CmpInst::Predicate minMaxToCompare(unsigned Opc) {
3850   switch (Opc) {
3851   case TargetOpcode::G_SMIN:
3852     return CmpInst::ICMP_SLT;
3853   case TargetOpcode::G_SMAX:
3854     return CmpInst::ICMP_SGT;
3855   case TargetOpcode::G_UMIN:
3856     return CmpInst::ICMP_ULT;
3857   case TargetOpcode::G_UMAX:
3858     return CmpInst::ICMP_UGT;
3859   default:
3860     llvm_unreachable("not in integer min/max");
3861   }
3862 }
3863 
3864 LegalizerHelper::LegalizeResult
3865 LegalizerHelper::lowerMinMax(MachineInstr &MI, unsigned TypeIdx, LLT Ty) {
3866   Register Dst = MI.getOperand(0).getReg();
3867   Register Src0 = MI.getOperand(1).getReg();
3868   Register Src1 = MI.getOperand(2).getReg();
3869 
3870   const CmpInst::Predicate Pred = minMaxToCompare(MI.getOpcode());
3871   LLT CmpType = MRI.getType(Dst).changeElementSize(1);
3872 
3873   auto Cmp = MIRBuilder.buildICmp(Pred, CmpType, Src0, Src1);
3874   MIRBuilder.buildSelect(Dst, Cmp, Src0, Src1);
3875 
3876   MI.eraseFromParent();
3877   return Legalized;
3878 }
3879 
3880 LegalizerHelper::LegalizeResult
3881 LegalizerHelper::lowerFCopySign(MachineInstr &MI, unsigned TypeIdx, LLT Ty) {
3882   Register Dst = MI.getOperand(0).getReg();
3883   Register Src0 = MI.getOperand(1).getReg();
3884   Register Src1 = MI.getOperand(2).getReg();
3885 
3886   const LLT Src0Ty = MRI.getType(Src0);
3887   const LLT Src1Ty = MRI.getType(Src1);
3888 
3889   const int Src0Size = Src0Ty.getScalarSizeInBits();
3890   const int Src1Size = Src1Ty.getScalarSizeInBits();
3891 
3892   auto SignBitMask = MIRBuilder.buildConstant(
3893     Src0Ty, APInt::getSignMask(Src0Size));
3894 
3895   auto NotSignBitMask = MIRBuilder.buildConstant(
3896     Src0Ty, APInt::getLowBitsSet(Src0Size, Src0Size - 1));
3897 
3898   auto And0 = MIRBuilder.buildAnd(Src0Ty, Src0, NotSignBitMask);
3899   MachineInstr *Or;
3900 
3901   if (Src0Ty == Src1Ty) {
3902     auto And1 = MIRBuilder.buildAnd(Src1Ty, Src0, SignBitMask);
3903     Or = MIRBuilder.buildOr(Dst, And0, And1);
3904   } else if (Src0Size > Src1Size) {
3905     auto ShiftAmt = MIRBuilder.buildConstant(Src0Ty, Src0Size - Src1Size);
3906     auto Zext = MIRBuilder.buildZExt(Src0Ty, Src1);
3907     auto Shift = MIRBuilder.buildShl(Src0Ty, Zext, ShiftAmt);
3908     auto And1 = MIRBuilder.buildAnd(Src0Ty, Shift, SignBitMask);
3909     Or = MIRBuilder.buildOr(Dst, And0, And1);
3910   } else {
3911     auto ShiftAmt = MIRBuilder.buildConstant(Src1Ty, Src1Size - Src0Size);
3912     auto Shift = MIRBuilder.buildLShr(Src1Ty, Src1, ShiftAmt);
3913     auto Trunc = MIRBuilder.buildTrunc(Src0Ty, Shift);
3914     auto And1 = MIRBuilder.buildAnd(Src0Ty, Trunc, SignBitMask);
3915     Or = MIRBuilder.buildOr(Dst, And0, And1);
3916   }
3917 
3918   // Be careful about setting nsz/nnan/ninf on every instruction, since the
3919   // constants are a nan and -0.0, but the final result should preserve
3920   // everything.
3921   if (unsigned Flags = MI.getFlags())
3922     Or->setFlags(Flags);
3923 
3924   MI.eraseFromParent();
3925   return Legalized;
3926 }
3927 
3928 LegalizerHelper::LegalizeResult
3929 LegalizerHelper::lowerFMinNumMaxNum(MachineInstr &MI) {
3930   unsigned NewOp = MI.getOpcode() == TargetOpcode::G_FMINNUM ?
3931     TargetOpcode::G_FMINNUM_IEEE : TargetOpcode::G_FMAXNUM_IEEE;
3932 
3933   Register Dst = MI.getOperand(0).getReg();
3934   Register Src0 = MI.getOperand(1).getReg();
3935   Register Src1 = MI.getOperand(2).getReg();
3936   LLT Ty = MRI.getType(Dst);
3937 
3938   if (!MI.getFlag(MachineInstr::FmNoNans)) {
3939     // Insert canonicalizes if it's possible we need to quiet to get correct
3940     // sNaN behavior.
3941 
3942     // Note this must be done here, and not as an optimization combine in the
3943     // absence of a dedicate quiet-snan instruction as we're using an
3944     // omni-purpose G_FCANONICALIZE.
3945     if (!isKnownNeverSNaN(Src0, MRI))
3946       Src0 = MIRBuilder.buildFCanonicalize(Ty, Src0, MI.getFlags()).getReg(0);
3947 
3948     if (!isKnownNeverSNaN(Src1, MRI))
3949       Src1 = MIRBuilder.buildFCanonicalize(Ty, Src1, MI.getFlags()).getReg(0);
3950   }
3951 
3952   // If there are no nans, it's safe to simply replace this with the non-IEEE
3953   // version.
3954   MIRBuilder.buildInstr(NewOp, {Dst}, {Src0, Src1}, MI.getFlags());
3955   MI.eraseFromParent();
3956   return Legalized;
3957 }
3958 
3959 LegalizerHelper::LegalizeResult LegalizerHelper::lowerFMad(MachineInstr &MI) {
3960   // Expand G_FMAD a, b, c -> G_FADD (G_FMUL a, b), c
3961   Register DstReg = MI.getOperand(0).getReg();
3962   LLT Ty = MRI.getType(DstReg);
3963   unsigned Flags = MI.getFlags();
3964 
3965   auto Mul = MIRBuilder.buildFMul(Ty, MI.getOperand(1), MI.getOperand(2),
3966                                   Flags);
3967   MIRBuilder.buildFAdd(DstReg, Mul, MI.getOperand(3), Flags);
3968   MI.eraseFromParent();
3969   return Legalized;
3970 }
3971 
3972 LegalizerHelper::LegalizeResult
3973 LegalizerHelper::lowerUnmergeValues(MachineInstr &MI) {
3974   const unsigned NumDst = MI.getNumOperands() - 1;
3975   const Register SrcReg = MI.getOperand(NumDst).getReg();
3976   LLT SrcTy = MRI.getType(SrcReg);
3977 
3978   Register Dst0Reg = MI.getOperand(0).getReg();
3979   LLT DstTy = MRI.getType(Dst0Reg);
3980 
3981 
3982   // Expand scalarizing unmerge as bitcast to integer and shift.
3983   if (!DstTy.isVector() && SrcTy.isVector() &&
3984       SrcTy.getElementType() == DstTy) {
3985     LLT IntTy = LLT::scalar(SrcTy.getSizeInBits());
3986     Register Cast = MIRBuilder.buildBitcast(IntTy, SrcReg).getReg(0);
3987 
3988     MIRBuilder.buildTrunc(Dst0Reg, Cast);
3989 
3990     const unsigned DstSize = DstTy.getSizeInBits();
3991     unsigned Offset = DstSize;
3992     for (unsigned I = 1; I != NumDst; ++I, Offset += DstSize) {
3993       auto ShiftAmt = MIRBuilder.buildConstant(IntTy, Offset);
3994       auto Shift = MIRBuilder.buildLShr(IntTy, Cast, ShiftAmt);
3995       MIRBuilder.buildTrunc(MI.getOperand(I), Shift);
3996     }
3997 
3998     MI.eraseFromParent();
3999     return Legalized;
4000   }
4001 
4002   return UnableToLegalize;
4003 }
4004 
4005 LegalizerHelper::LegalizeResult
4006 LegalizerHelper::lowerShuffleVector(MachineInstr &MI) {
4007   Register DstReg = MI.getOperand(0).getReg();
4008   Register Src0Reg = MI.getOperand(1).getReg();
4009   Register Src1Reg = MI.getOperand(2).getReg();
4010   LLT Src0Ty = MRI.getType(Src0Reg);
4011   LLT DstTy = MRI.getType(DstReg);
4012   LLT IdxTy = LLT::scalar(32);
4013 
4014   const Constant *ShufMask = MI.getOperand(3).getShuffleMask();
4015 
4016   SmallVector<int, 32> Mask;
4017   ShuffleVectorInst::getShuffleMask(ShufMask, Mask);
4018 
4019   if (DstTy.isScalar()) {
4020     if (Src0Ty.isVector())
4021       return UnableToLegalize;
4022 
4023     // This is just a SELECT.
4024     assert(Mask.size() == 1 && "Expected a single mask element");
4025     Register Val;
4026     if (Mask[0] < 0 || Mask[0] > 1)
4027       Val = MIRBuilder.buildUndef(DstTy).getReg(0);
4028     else
4029       Val = Mask[0] == 0 ? Src0Reg : Src1Reg;
4030     MIRBuilder.buildCopy(DstReg, Val);
4031     MI.eraseFromParent();
4032     return Legalized;
4033   }
4034 
4035   Register Undef;
4036   SmallVector<Register, 32> BuildVec;
4037   LLT EltTy = DstTy.getElementType();
4038 
4039   for (int Idx : Mask) {
4040     if (Idx < 0) {
4041       if (!Undef.isValid())
4042         Undef = MIRBuilder.buildUndef(EltTy).getReg(0);
4043       BuildVec.push_back(Undef);
4044       continue;
4045     }
4046 
4047     if (Src0Ty.isScalar()) {
4048       BuildVec.push_back(Idx == 0 ? Src0Reg : Src1Reg);
4049     } else {
4050       int NumElts = Src0Ty.getNumElements();
4051       Register SrcVec = Idx < NumElts ? Src0Reg : Src1Reg;
4052       int ExtractIdx = Idx < NumElts ? Idx : Idx - NumElts;
4053       auto IdxK = MIRBuilder.buildConstant(IdxTy, ExtractIdx);
4054       auto Extract = MIRBuilder.buildExtractVectorElement(EltTy, SrcVec, IdxK);
4055       BuildVec.push_back(Extract.getReg(0));
4056     }
4057   }
4058 
4059   MIRBuilder.buildBuildVector(DstReg, BuildVec);
4060   MI.eraseFromParent();
4061   return Legalized;
4062 }
4063 
4064 LegalizerHelper::LegalizeResult
4065 LegalizerHelper::lowerDynStackAlloc(MachineInstr &MI) {
4066   Register Dst = MI.getOperand(0).getReg();
4067   Register AllocSize = MI.getOperand(1).getReg();
4068   unsigned Align = MI.getOperand(2).getImm();
4069 
4070   const auto &MF = *MI.getMF();
4071   const auto &TLI = *MF.getSubtarget().getTargetLowering();
4072 
4073   LLT PtrTy = MRI.getType(Dst);
4074   LLT IntPtrTy = LLT::scalar(PtrTy.getSizeInBits());
4075 
4076   Register SPReg = TLI.getStackPointerRegisterToSaveRestore();
4077   auto SPTmp = MIRBuilder.buildCopy(PtrTy, SPReg);
4078   SPTmp = MIRBuilder.buildCast(IntPtrTy, SPTmp);
4079 
4080   // Subtract the final alloc from the SP. We use G_PTRTOINT here so we don't
4081   // have to generate an extra instruction to negate the alloc and then use
4082   // G_GEP to add the negative offset.
4083   auto Alloc = MIRBuilder.buildSub(IntPtrTy, SPTmp, AllocSize);
4084   if (Align) {
4085     APInt AlignMask(IntPtrTy.getSizeInBits(), Align, true);
4086     AlignMask.negate();
4087     auto AlignCst = MIRBuilder.buildConstant(IntPtrTy, AlignMask);
4088     Alloc = MIRBuilder.buildAnd(IntPtrTy, Alloc, AlignCst);
4089   }
4090 
4091   SPTmp = MIRBuilder.buildCast(PtrTy, Alloc);
4092   MIRBuilder.buildCopy(SPReg, SPTmp);
4093   MIRBuilder.buildCopy(Dst, SPTmp);
4094 
4095   MI.eraseFromParent();
4096   return Legalized;
4097 }
4098