xref: /llvm-project/llvm/lib/Target/ARM/ARMLegalizerInfo.cpp (revision 52e5683ddddad787caf15c8edfd34eb4a9c8704a)
1 //===- ARMLegalizerInfo.cpp --------------------------------------*- C++ -*-==//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 /// \file
9 /// This file implements the targeting of the Machinelegalizer class for ARM.
10 /// \todo This should be generated by TableGen.
11 //===----------------------------------------------------------------------===//
12 
13 #include "ARMLegalizerInfo.h"
14 #include "ARMCallLowering.h"
15 #include "ARMSubtarget.h"
16 #include "llvm/CodeGen/GlobalISel/LegalizerHelper.h"
17 #include "llvm/CodeGen/GlobalISel/MachineIRBuilder.h"
18 #include "llvm/CodeGen/LowLevelTypeUtils.h"
19 #include "llvm/CodeGen/MachineRegisterInfo.h"
20 #include "llvm/CodeGen/TargetOpcodes.h"
21 #include "llvm/CodeGen/ValueTypes.h"
22 #include "llvm/IR/DerivedTypes.h"
23 #include "llvm/IR/Type.h"
24 
25 using namespace llvm;
26 using namespace LegalizeActions;
27 
28 static bool AEABI(const ARMSubtarget &ST) {
29   return ST.isTargetAEABI() || ST.isTargetGNUAEABI() || ST.isTargetMuslAEABI();
30 }
31 
32 ARMLegalizerInfo::ARMLegalizerInfo(const ARMSubtarget &ST) : ST(ST) {
33   using namespace TargetOpcode;
34 
35   const LLT p0 = LLT::pointer(0, 32);
36 
37   const LLT s1 = LLT::scalar(1);
38   const LLT s8 = LLT::scalar(8);
39   const LLT s16 = LLT::scalar(16);
40   const LLT s32 = LLT::scalar(32);
41   const LLT s64 = LLT::scalar(64);
42 
43   auto &LegacyInfo = getLegacyLegalizerInfo();
44   if (ST.isThumb1Only()) {
45     // Thumb1 is not supported yet.
46     LegacyInfo.computeTables();
47     verify(*ST.getInstrInfo());
48     return;
49   }
50 
51   getActionDefinitionsBuilder({G_SEXT, G_ZEXT, G_ANYEXT})
52       .legalForCartesianProduct({s8, s16, s32}, {s1, s8, s16});
53 
54   getActionDefinitionsBuilder(G_SEXT_INREG).lower();
55 
56   getActionDefinitionsBuilder({G_MUL, G_AND, G_OR, G_XOR})
57       .legalFor({s32})
58       .clampScalar(0, s32, s32);
59 
60   if (ST.hasNEON())
61     getActionDefinitionsBuilder({G_ADD, G_SUB})
62         .legalFor({s32, s64})
63         .minScalar(0, s32);
64   else
65     getActionDefinitionsBuilder({G_ADD, G_SUB})
66         .legalFor({s32})
67         .minScalar(0, s32);
68 
69   getActionDefinitionsBuilder({G_ASHR, G_LSHR, G_SHL})
70     .legalFor({{s32, s32}})
71     .minScalar(0, s32)
72     .clampScalar(1, s32, s32);
73 
74   bool HasHWDivide = (!ST.isThumb() && ST.hasDivideInARMMode()) ||
75                      (ST.isThumb() && ST.hasDivideInThumbMode());
76   if (HasHWDivide)
77     getActionDefinitionsBuilder({G_SDIV, G_UDIV})
78         .legalFor({s32})
79         .clampScalar(0, s32, s32);
80   else
81     getActionDefinitionsBuilder({G_SDIV, G_UDIV})
82         .libcallFor({s32})
83         .clampScalar(0, s32, s32);
84 
85   auto &REMBuilder =
86       getActionDefinitionsBuilder({G_SREM, G_UREM}).minScalar(0, s32);
87   if (HasHWDivide)
88     REMBuilder.lowerFor({s32});
89   else if (AEABI(ST))
90     REMBuilder.customFor({s32});
91   else
92     REMBuilder.libcallFor({s32});
93 
94   getActionDefinitionsBuilder(G_INTTOPTR)
95       .legalFor({{p0, s32}})
96       .minScalar(1, s32);
97   getActionDefinitionsBuilder(G_PTRTOINT)
98       .legalFor({{s32, p0}})
99       .minScalar(0, s32);
100 
101   getActionDefinitionsBuilder(G_CONSTANT)
102       .customFor({s32, p0})
103       .clampScalar(0, s32, s32);
104 
105   getActionDefinitionsBuilder(G_CONSTANT_POOL).legalFor({p0});
106 
107   getActionDefinitionsBuilder(G_ICMP)
108       .legalForCartesianProduct({s1}, {s32, p0})
109       .minScalar(1, s32);
110 
111   getActionDefinitionsBuilder(G_SELECT)
112       .legalForCartesianProduct({s32, p0}, {s1})
113       .minScalar(0, s32);
114 
115   // We're keeping these builders around because we'll want to add support for
116   // floating point to them.
117   auto &LoadStoreBuilder = getActionDefinitionsBuilder({G_LOAD, G_STORE})
118                                .legalForTypesWithMemDesc({{s8, p0, s8, 8},
119                                                           {s16, p0, s16, 8},
120                                                           {s32, p0, s32, 8},
121                                                           {p0, p0, p0, 8}})
122                                .unsupportedIfMemSizeNotPow2();
123 
124   getActionDefinitionsBuilder(G_FRAME_INDEX).legalFor({p0});
125   getActionDefinitionsBuilder(G_GLOBAL_VALUE).legalFor({p0});
126 
127   auto &PhiBuilder =
128       getActionDefinitionsBuilder(G_PHI)
129           .legalFor({s32, p0})
130           .minScalar(0, s32);
131 
132   getActionDefinitionsBuilder(G_PTR_ADD)
133       .legalFor({{p0, s32}})
134       .minScalar(1, s32);
135 
136   getActionDefinitionsBuilder(G_BRCOND).legalFor({s1});
137 
138   if (!ST.useSoftFloat() && ST.hasVFP2Base()) {
139     getActionDefinitionsBuilder(
140         {G_FADD, G_FSUB, G_FMUL, G_FDIV, G_FCONSTANT, G_FNEG})
141         .legalFor({s32, s64});
142 
143     LoadStoreBuilder
144         .legalForTypesWithMemDesc({{s64, p0, s64, 32}})
145         .maxScalar(0, s32);
146     PhiBuilder.legalFor({s64});
147 
148     getActionDefinitionsBuilder(G_FCMP).legalForCartesianProduct({s1},
149                                                                  {s32, s64});
150 
151     getActionDefinitionsBuilder(G_MERGE_VALUES).legalFor({{s64, s32}});
152     getActionDefinitionsBuilder(G_UNMERGE_VALUES).legalFor({{s32, s64}});
153 
154     getActionDefinitionsBuilder(G_FPEXT).legalFor({{s64, s32}});
155     getActionDefinitionsBuilder(G_FPTRUNC).legalFor({{s32, s64}});
156 
157     getActionDefinitionsBuilder({G_FPTOSI, G_FPTOUI})
158         .legalForCartesianProduct({s32}, {s32, s64});
159     getActionDefinitionsBuilder({G_SITOFP, G_UITOFP})
160         .legalForCartesianProduct({s32, s64}, {s32});
161 
162     getActionDefinitionsBuilder({G_GET_FPENV, G_SET_FPENV, G_GET_FPMODE})
163         .legalFor({s32});
164     getActionDefinitionsBuilder(G_RESET_FPENV).alwaysLegal();
165     getActionDefinitionsBuilder(G_SET_FPMODE).customFor({s32});
166   } else {
167     getActionDefinitionsBuilder({G_FADD, G_FSUB, G_FMUL, G_FDIV})
168         .libcallFor({s32, s64});
169 
170     LoadStoreBuilder.maxScalar(0, s32);
171 
172     getActionDefinitionsBuilder(G_FNEG).lowerFor({s32, s64});
173 
174     getActionDefinitionsBuilder(G_FCONSTANT).customFor({s32, s64});
175 
176     getActionDefinitionsBuilder(G_FCMP).customForCartesianProduct({s1},
177                                                                   {s32, s64});
178 
179     if (AEABI(ST))
180       setFCmpLibcallsAEABI();
181     else
182       setFCmpLibcallsGNU();
183 
184     getActionDefinitionsBuilder(G_FPEXT).libcallFor({{s64, s32}});
185     getActionDefinitionsBuilder(G_FPTRUNC).libcallFor({{s32, s64}});
186 
187     getActionDefinitionsBuilder({G_FPTOSI, G_FPTOUI})
188         .libcallForCartesianProduct({s32}, {s32, s64});
189     getActionDefinitionsBuilder({G_SITOFP, G_UITOFP})
190         .libcallForCartesianProduct({s32, s64}, {s32});
191 
192     getActionDefinitionsBuilder({G_GET_FPENV, G_SET_FPENV, G_RESET_FPENV})
193         .libcall();
194     getActionDefinitionsBuilder({G_GET_FPMODE, G_SET_FPMODE, G_RESET_FPMODE})
195         .libcall();
196   }
197 
198   // Just expand whatever loads and stores are left.
199   LoadStoreBuilder.lower();
200 
201   if (!ST.useSoftFloat() && ST.hasVFP4Base())
202     getActionDefinitionsBuilder(G_FMA).legalFor({s32, s64});
203   else
204     getActionDefinitionsBuilder(G_FMA).libcallFor({s32, s64});
205 
206   getActionDefinitionsBuilder({G_FREM, G_FPOW}).libcallFor({s32, s64});
207 
208   if (ST.hasV5TOps()) {
209     getActionDefinitionsBuilder(G_CTLZ)
210         .legalFor({s32, s32})
211         .clampScalar(1, s32, s32)
212         .clampScalar(0, s32, s32);
213     getActionDefinitionsBuilder(G_CTLZ_ZERO_UNDEF)
214         .lowerFor({s32, s32})
215         .clampScalar(1, s32, s32)
216         .clampScalar(0, s32, s32);
217   } else {
218     getActionDefinitionsBuilder(G_CTLZ_ZERO_UNDEF)
219         .libcallFor({s32, s32})
220         .clampScalar(1, s32, s32)
221         .clampScalar(0, s32, s32);
222     getActionDefinitionsBuilder(G_CTLZ)
223         .lowerFor({s32, s32})
224         .clampScalar(1, s32, s32)
225         .clampScalar(0, s32, s32);
226   }
227 
228   LegacyInfo.computeTables();
229   verify(*ST.getInstrInfo());
230 }
231 
232 void ARMLegalizerInfo::setFCmpLibcallsAEABI() {
233   // FCMP_TRUE and FCMP_FALSE don't need libcalls, they should be
234   // default-initialized.
235   FCmp32Libcalls.resize(CmpInst::LAST_FCMP_PREDICATE + 1);
236   FCmp32Libcalls[CmpInst::FCMP_OEQ] = {
237       {RTLIB::OEQ_F32, CmpInst::BAD_ICMP_PREDICATE}};
238   FCmp32Libcalls[CmpInst::FCMP_OGE] = {
239       {RTLIB::OGE_F32, CmpInst::BAD_ICMP_PREDICATE}};
240   FCmp32Libcalls[CmpInst::FCMP_OGT] = {
241       {RTLIB::OGT_F32, CmpInst::BAD_ICMP_PREDICATE}};
242   FCmp32Libcalls[CmpInst::FCMP_OLE] = {
243       {RTLIB::OLE_F32, CmpInst::BAD_ICMP_PREDICATE}};
244   FCmp32Libcalls[CmpInst::FCMP_OLT] = {
245       {RTLIB::OLT_F32, CmpInst::BAD_ICMP_PREDICATE}};
246   FCmp32Libcalls[CmpInst::FCMP_ORD] = {{RTLIB::UO_F32, CmpInst::ICMP_EQ}};
247   FCmp32Libcalls[CmpInst::FCMP_UGE] = {{RTLIB::OLT_F32, CmpInst::ICMP_EQ}};
248   FCmp32Libcalls[CmpInst::FCMP_UGT] = {{RTLIB::OLE_F32, CmpInst::ICMP_EQ}};
249   FCmp32Libcalls[CmpInst::FCMP_ULE] = {{RTLIB::OGT_F32, CmpInst::ICMP_EQ}};
250   FCmp32Libcalls[CmpInst::FCMP_ULT] = {{RTLIB::OGE_F32, CmpInst::ICMP_EQ}};
251   FCmp32Libcalls[CmpInst::FCMP_UNE] = {{RTLIB::UNE_F32, CmpInst::ICMP_EQ}};
252   FCmp32Libcalls[CmpInst::FCMP_UNO] = {
253       {RTLIB::UO_F32, CmpInst::BAD_ICMP_PREDICATE}};
254   FCmp32Libcalls[CmpInst::FCMP_ONE] = {
255       {RTLIB::OGT_F32, CmpInst::BAD_ICMP_PREDICATE},
256       {RTLIB::OLT_F32, CmpInst::BAD_ICMP_PREDICATE}};
257   FCmp32Libcalls[CmpInst::FCMP_UEQ] = {
258       {RTLIB::OEQ_F32, CmpInst::BAD_ICMP_PREDICATE},
259       {RTLIB::UO_F32, CmpInst::BAD_ICMP_PREDICATE}};
260 
261   FCmp64Libcalls.resize(CmpInst::LAST_FCMP_PREDICATE + 1);
262   FCmp64Libcalls[CmpInst::FCMP_OEQ] = {
263       {RTLIB::OEQ_F64, CmpInst::BAD_ICMP_PREDICATE}};
264   FCmp64Libcalls[CmpInst::FCMP_OGE] = {
265       {RTLIB::OGE_F64, CmpInst::BAD_ICMP_PREDICATE}};
266   FCmp64Libcalls[CmpInst::FCMP_OGT] = {
267       {RTLIB::OGT_F64, CmpInst::BAD_ICMP_PREDICATE}};
268   FCmp64Libcalls[CmpInst::FCMP_OLE] = {
269       {RTLIB::OLE_F64, CmpInst::BAD_ICMP_PREDICATE}};
270   FCmp64Libcalls[CmpInst::FCMP_OLT] = {
271       {RTLIB::OLT_F64, CmpInst::BAD_ICMP_PREDICATE}};
272   FCmp64Libcalls[CmpInst::FCMP_ORD] = {{RTLIB::UO_F64, CmpInst::ICMP_EQ}};
273   FCmp64Libcalls[CmpInst::FCMP_UGE] = {{RTLIB::OLT_F64, CmpInst::ICMP_EQ}};
274   FCmp64Libcalls[CmpInst::FCMP_UGT] = {{RTLIB::OLE_F64, CmpInst::ICMP_EQ}};
275   FCmp64Libcalls[CmpInst::FCMP_ULE] = {{RTLIB::OGT_F64, CmpInst::ICMP_EQ}};
276   FCmp64Libcalls[CmpInst::FCMP_ULT] = {{RTLIB::OGE_F64, CmpInst::ICMP_EQ}};
277   FCmp64Libcalls[CmpInst::FCMP_UNE] = {{RTLIB::UNE_F64, CmpInst::ICMP_EQ}};
278   FCmp64Libcalls[CmpInst::FCMP_UNO] = {
279       {RTLIB::UO_F64, CmpInst::BAD_ICMP_PREDICATE}};
280   FCmp64Libcalls[CmpInst::FCMP_ONE] = {
281       {RTLIB::OGT_F64, CmpInst::BAD_ICMP_PREDICATE},
282       {RTLIB::OLT_F64, CmpInst::BAD_ICMP_PREDICATE}};
283   FCmp64Libcalls[CmpInst::FCMP_UEQ] = {
284       {RTLIB::OEQ_F64, CmpInst::BAD_ICMP_PREDICATE},
285       {RTLIB::UO_F64, CmpInst::BAD_ICMP_PREDICATE}};
286 }
287 
288 void ARMLegalizerInfo::setFCmpLibcallsGNU() {
289   // FCMP_TRUE and FCMP_FALSE don't need libcalls, they should be
290   // default-initialized.
291   FCmp32Libcalls.resize(CmpInst::LAST_FCMP_PREDICATE + 1);
292   FCmp32Libcalls[CmpInst::FCMP_OEQ] = {{RTLIB::OEQ_F32, CmpInst::ICMP_EQ}};
293   FCmp32Libcalls[CmpInst::FCMP_OGE] = {{RTLIB::OGE_F32, CmpInst::ICMP_SGE}};
294   FCmp32Libcalls[CmpInst::FCMP_OGT] = {{RTLIB::OGT_F32, CmpInst::ICMP_SGT}};
295   FCmp32Libcalls[CmpInst::FCMP_OLE] = {{RTLIB::OLE_F32, CmpInst::ICMP_SLE}};
296   FCmp32Libcalls[CmpInst::FCMP_OLT] = {{RTLIB::OLT_F32, CmpInst::ICMP_SLT}};
297   FCmp32Libcalls[CmpInst::FCMP_ORD] = {{RTLIB::UO_F32, CmpInst::ICMP_EQ}};
298   FCmp32Libcalls[CmpInst::FCMP_UGE] = {{RTLIB::OLT_F32, CmpInst::ICMP_SGE}};
299   FCmp32Libcalls[CmpInst::FCMP_UGT] = {{RTLIB::OLE_F32, CmpInst::ICMP_SGT}};
300   FCmp32Libcalls[CmpInst::FCMP_ULE] = {{RTLIB::OGT_F32, CmpInst::ICMP_SLE}};
301   FCmp32Libcalls[CmpInst::FCMP_ULT] = {{RTLIB::OGE_F32, CmpInst::ICMP_SLT}};
302   FCmp32Libcalls[CmpInst::FCMP_UNE] = {{RTLIB::UNE_F32, CmpInst::ICMP_NE}};
303   FCmp32Libcalls[CmpInst::FCMP_UNO] = {{RTLIB::UO_F32, CmpInst::ICMP_NE}};
304   FCmp32Libcalls[CmpInst::FCMP_ONE] = {{RTLIB::OGT_F32, CmpInst::ICMP_SGT},
305                                        {RTLIB::OLT_F32, CmpInst::ICMP_SLT}};
306   FCmp32Libcalls[CmpInst::FCMP_UEQ] = {{RTLIB::OEQ_F32, CmpInst::ICMP_EQ},
307                                        {RTLIB::UO_F32, CmpInst::ICMP_NE}};
308 
309   FCmp64Libcalls.resize(CmpInst::LAST_FCMP_PREDICATE + 1);
310   FCmp64Libcalls[CmpInst::FCMP_OEQ] = {{RTLIB::OEQ_F64, CmpInst::ICMP_EQ}};
311   FCmp64Libcalls[CmpInst::FCMP_OGE] = {{RTLIB::OGE_F64, CmpInst::ICMP_SGE}};
312   FCmp64Libcalls[CmpInst::FCMP_OGT] = {{RTLIB::OGT_F64, CmpInst::ICMP_SGT}};
313   FCmp64Libcalls[CmpInst::FCMP_OLE] = {{RTLIB::OLE_F64, CmpInst::ICMP_SLE}};
314   FCmp64Libcalls[CmpInst::FCMP_OLT] = {{RTLIB::OLT_F64, CmpInst::ICMP_SLT}};
315   FCmp64Libcalls[CmpInst::FCMP_ORD] = {{RTLIB::UO_F64, CmpInst::ICMP_EQ}};
316   FCmp64Libcalls[CmpInst::FCMP_UGE] = {{RTLIB::OLT_F64, CmpInst::ICMP_SGE}};
317   FCmp64Libcalls[CmpInst::FCMP_UGT] = {{RTLIB::OLE_F64, CmpInst::ICMP_SGT}};
318   FCmp64Libcalls[CmpInst::FCMP_ULE] = {{RTLIB::OGT_F64, CmpInst::ICMP_SLE}};
319   FCmp64Libcalls[CmpInst::FCMP_ULT] = {{RTLIB::OGE_F64, CmpInst::ICMP_SLT}};
320   FCmp64Libcalls[CmpInst::FCMP_UNE] = {{RTLIB::UNE_F64, CmpInst::ICMP_NE}};
321   FCmp64Libcalls[CmpInst::FCMP_UNO] = {{RTLIB::UO_F64, CmpInst::ICMP_NE}};
322   FCmp64Libcalls[CmpInst::FCMP_ONE] = {{RTLIB::OGT_F64, CmpInst::ICMP_SGT},
323                                        {RTLIB::OLT_F64, CmpInst::ICMP_SLT}};
324   FCmp64Libcalls[CmpInst::FCMP_UEQ] = {{RTLIB::OEQ_F64, CmpInst::ICMP_EQ},
325                                        {RTLIB::UO_F64, CmpInst::ICMP_NE}};
326 }
327 
328 ARMLegalizerInfo::FCmpLibcallsList
329 ARMLegalizerInfo::getFCmpLibcalls(CmpInst::Predicate Predicate,
330                                   unsigned Size) const {
331   assert(CmpInst::isFPPredicate(Predicate) && "Unsupported FCmp predicate");
332   if (Size == 32)
333     return FCmp32Libcalls[Predicate];
334   if (Size == 64)
335     return FCmp64Libcalls[Predicate];
336   llvm_unreachable("Unsupported size for FCmp predicate");
337 }
338 
339 bool ARMLegalizerInfo::legalizeCustom(LegalizerHelper &Helper, MachineInstr &MI,
340                                       LostDebugLocObserver &LocObserver) const {
341   using namespace TargetOpcode;
342 
343   MachineIRBuilder &MIRBuilder = Helper.MIRBuilder;
344   MachineRegisterInfo &MRI = *MIRBuilder.getMRI();
345   LLVMContext &Ctx = MIRBuilder.getMF().getFunction().getContext();
346 
347   switch (MI.getOpcode()) {
348   default:
349     return false;
350   case G_SREM:
351   case G_UREM: {
352     Register OriginalResult = MI.getOperand(0).getReg();
353     auto Size = MRI.getType(OriginalResult).getSizeInBits();
354     if (Size != 32)
355       return false;
356 
357     auto Libcall =
358         MI.getOpcode() == G_SREM ? RTLIB::SDIVREM_I32 : RTLIB::UDIVREM_I32;
359 
360     // Our divmod libcalls return a struct containing the quotient and the
361     // remainder. Create a new, unused register for the quotient and use the
362     // destination of the original instruction for the remainder.
363     Type *ArgTy = Type::getInt32Ty(Ctx);
364     StructType *RetTy = StructType::get(Ctx, {ArgTy, ArgTy}, /* Packed */ true);
365     Register RetRegs[] = {MRI.createGenericVirtualRegister(LLT::scalar(32)),
366                           OriginalResult};
367     auto Status = createLibcall(MIRBuilder, Libcall, {RetRegs, RetTy, 0},
368                                 {{MI.getOperand(1).getReg(), ArgTy, 0},
369                                  {MI.getOperand(2).getReg(), ArgTy, 0}},
370                                 LocObserver, &MI);
371     if (Status != LegalizerHelper::Legalized)
372       return false;
373     break;
374   }
375   case G_FCMP: {
376     assert(MRI.getType(MI.getOperand(2).getReg()) ==
377                MRI.getType(MI.getOperand(3).getReg()) &&
378            "Mismatched operands for G_FCMP");
379     auto OpSize = MRI.getType(MI.getOperand(2).getReg()).getSizeInBits();
380 
381     auto OriginalResult = MI.getOperand(0).getReg();
382     auto Predicate =
383         static_cast<CmpInst::Predicate>(MI.getOperand(1).getPredicate());
384     auto Libcalls = getFCmpLibcalls(Predicate, OpSize);
385 
386     if (Libcalls.empty()) {
387       assert((Predicate == CmpInst::FCMP_TRUE ||
388               Predicate == CmpInst::FCMP_FALSE) &&
389              "Predicate needs libcalls, but none specified");
390       MIRBuilder.buildConstant(OriginalResult,
391                                Predicate == CmpInst::FCMP_TRUE ? 1 : 0);
392       MI.eraseFromParent();
393       return true;
394     }
395 
396     assert((OpSize == 32 || OpSize == 64) && "Unsupported operand size");
397     auto *ArgTy = OpSize == 32 ? Type::getFloatTy(Ctx) : Type::getDoubleTy(Ctx);
398     auto *RetTy = Type::getInt32Ty(Ctx);
399 
400     SmallVector<Register, 2> Results;
401     for (auto Libcall : Libcalls) {
402       auto LibcallResult = MRI.createGenericVirtualRegister(LLT::scalar(32));
403       auto Status = createLibcall(MIRBuilder, Libcall.LibcallID,
404                                   {LibcallResult, RetTy, 0},
405                                   {{MI.getOperand(2).getReg(), ArgTy, 0},
406                                    {MI.getOperand(3).getReg(), ArgTy, 0}},
407                                   LocObserver, &MI);
408 
409       if (Status != LegalizerHelper::Legalized)
410         return false;
411 
412       auto ProcessedResult =
413           Libcalls.size() == 1
414               ? OriginalResult
415               : MRI.createGenericVirtualRegister(MRI.getType(OriginalResult));
416 
417       // We have a result, but we need to transform it into a proper 1-bit 0 or
418       // 1, taking into account the different peculiarities of the values
419       // returned by the comparison functions.
420       CmpInst::Predicate ResultPred = Libcall.Predicate;
421       if (ResultPred == CmpInst::BAD_ICMP_PREDICATE) {
422         // We have a nice 0 or 1, and we just need to truncate it back to 1 bit
423         // to keep the types consistent.
424         MIRBuilder.buildTrunc(ProcessedResult, LibcallResult);
425       } else {
426         // We need to compare against 0.
427         assert(CmpInst::isIntPredicate(ResultPred) && "Unsupported predicate");
428         auto Zero = MIRBuilder.buildConstant(LLT::scalar(32), 0);
429         MIRBuilder.buildICmp(ResultPred, ProcessedResult, LibcallResult, Zero);
430       }
431       Results.push_back(ProcessedResult);
432     }
433 
434     if (Results.size() != 1) {
435       assert(Results.size() == 2 && "Unexpected number of results");
436       MIRBuilder.buildOr(OriginalResult, Results[0], Results[1]);
437     }
438     break;
439   }
440   case G_CONSTANT: {
441     const ConstantInt *ConstVal = MI.getOperand(1).getCImm();
442     uint64_t ImmVal = ConstVal->getZExtValue();
443     if (ConstantMaterializationCost(ImmVal, &ST) > 2 && !ST.genExecuteOnly())
444       return Helper.lowerConstant(MI) == LegalizerHelper::Legalized;
445     return true;
446   }
447   case G_FCONSTANT: {
448     // Convert to integer constants, while preserving the binary representation.
449     auto AsInteger =
450         MI.getOperand(1).getFPImm()->getValueAPF().bitcastToAPInt();
451     MIRBuilder.buildConstant(MI.getOperand(0),
452                              *ConstantInt::get(Ctx, AsInteger));
453     break;
454   }
455   case G_SET_FPMODE: {
456     // New FPSCR = (FPSCR & FPStatusBits) | (Modes & ~FPStatusBits)
457     LLT FPEnvTy = LLT::scalar(32);
458     auto FPEnv = MRI.createGenericVirtualRegister(FPEnvTy);
459     Register Modes = MI.getOperand(0).getReg();
460     MIRBuilder.buildGetFPEnv(FPEnv);
461     auto StatusBitMask = MIRBuilder.buildConstant(FPEnvTy, ARM::FPStatusBits);
462     auto StatusBits = MIRBuilder.buildAnd(FPEnvTy, FPEnv, StatusBitMask);
463     auto NotStatusBitMask =
464         MIRBuilder.buildConstant(FPEnvTy, ~ARM::FPStatusBits);
465     auto FPModeBits = MIRBuilder.buildAnd(FPEnvTy, Modes, NotStatusBitMask);
466     auto NewFPSCR = MIRBuilder.buildOr(FPEnvTy, StatusBits, FPModeBits);
467     MIRBuilder.buildSetFPEnv(NewFPSCR);
468     break;
469   }
470   }
471 
472   MI.eraseFromParent();
473   return true;
474 }
475