xref: /llvm-project/llvm/lib/Target/ARM/ARMLegalizerInfo.cpp (revision f97f96492dd08cdcb4b83775f764f09a396ed610)
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     getActionDefinitionsBuilder(G_RESET_FPMODE).custom();
167   } else {
168     getActionDefinitionsBuilder({G_FADD, G_FSUB, G_FMUL, G_FDIV})
169         .libcallFor({s32, s64});
170 
171     LoadStoreBuilder.maxScalar(0, s32);
172 
173     getActionDefinitionsBuilder(G_FNEG).lowerFor({s32, s64});
174 
175     getActionDefinitionsBuilder(G_FCONSTANT).customFor({s32, s64});
176 
177     getActionDefinitionsBuilder(G_FCMP).customForCartesianProduct({s1},
178                                                                   {s32, s64});
179 
180     if (AEABI(ST))
181       setFCmpLibcallsAEABI();
182     else
183       setFCmpLibcallsGNU();
184 
185     getActionDefinitionsBuilder(G_FPEXT).libcallFor({{s64, s32}});
186     getActionDefinitionsBuilder(G_FPTRUNC).libcallFor({{s32, s64}});
187 
188     getActionDefinitionsBuilder({G_FPTOSI, G_FPTOUI})
189         .libcallForCartesianProduct({s32}, {s32, s64});
190     getActionDefinitionsBuilder({G_SITOFP, G_UITOFP})
191         .libcallForCartesianProduct({s32, s64}, {s32});
192 
193     getActionDefinitionsBuilder({G_GET_FPENV, G_SET_FPENV, G_RESET_FPENV})
194         .libcall();
195     getActionDefinitionsBuilder({G_GET_FPMODE, G_SET_FPMODE, G_RESET_FPMODE})
196         .libcall();
197   }
198 
199   // Just expand whatever loads and stores are left.
200   LoadStoreBuilder.lower();
201 
202   if (!ST.useSoftFloat() && ST.hasVFP4Base())
203     getActionDefinitionsBuilder(G_FMA).legalFor({s32, s64});
204   else
205     getActionDefinitionsBuilder(G_FMA).libcallFor({s32, s64});
206 
207   getActionDefinitionsBuilder({G_FREM, G_FPOW}).libcallFor({s32, s64});
208 
209   if (ST.hasV5TOps()) {
210     getActionDefinitionsBuilder(G_CTLZ)
211         .legalFor({s32, s32})
212         .clampScalar(1, s32, s32)
213         .clampScalar(0, s32, s32);
214     getActionDefinitionsBuilder(G_CTLZ_ZERO_UNDEF)
215         .lowerFor({s32, s32})
216         .clampScalar(1, s32, s32)
217         .clampScalar(0, s32, s32);
218   } else {
219     getActionDefinitionsBuilder(G_CTLZ_ZERO_UNDEF)
220         .libcallFor({s32, s32})
221         .clampScalar(1, s32, s32)
222         .clampScalar(0, s32, s32);
223     getActionDefinitionsBuilder(G_CTLZ)
224         .lowerFor({s32, s32})
225         .clampScalar(1, s32, s32)
226         .clampScalar(0, s32, s32);
227   }
228 
229   LegacyInfo.computeTables();
230   verify(*ST.getInstrInfo());
231 }
232 
233 void ARMLegalizerInfo::setFCmpLibcallsAEABI() {
234   // FCMP_TRUE and FCMP_FALSE don't need libcalls, they should be
235   // default-initialized.
236   FCmp32Libcalls.resize(CmpInst::LAST_FCMP_PREDICATE + 1);
237   FCmp32Libcalls[CmpInst::FCMP_OEQ] = {
238       {RTLIB::OEQ_F32, CmpInst::BAD_ICMP_PREDICATE}};
239   FCmp32Libcalls[CmpInst::FCMP_OGE] = {
240       {RTLIB::OGE_F32, CmpInst::BAD_ICMP_PREDICATE}};
241   FCmp32Libcalls[CmpInst::FCMP_OGT] = {
242       {RTLIB::OGT_F32, CmpInst::BAD_ICMP_PREDICATE}};
243   FCmp32Libcalls[CmpInst::FCMP_OLE] = {
244       {RTLIB::OLE_F32, CmpInst::BAD_ICMP_PREDICATE}};
245   FCmp32Libcalls[CmpInst::FCMP_OLT] = {
246       {RTLIB::OLT_F32, CmpInst::BAD_ICMP_PREDICATE}};
247   FCmp32Libcalls[CmpInst::FCMP_ORD] = {{RTLIB::UO_F32, CmpInst::ICMP_EQ}};
248   FCmp32Libcalls[CmpInst::FCMP_UGE] = {{RTLIB::OLT_F32, CmpInst::ICMP_EQ}};
249   FCmp32Libcalls[CmpInst::FCMP_UGT] = {{RTLIB::OLE_F32, CmpInst::ICMP_EQ}};
250   FCmp32Libcalls[CmpInst::FCMP_ULE] = {{RTLIB::OGT_F32, CmpInst::ICMP_EQ}};
251   FCmp32Libcalls[CmpInst::FCMP_ULT] = {{RTLIB::OGE_F32, CmpInst::ICMP_EQ}};
252   FCmp32Libcalls[CmpInst::FCMP_UNE] = {{RTLIB::UNE_F32, CmpInst::ICMP_EQ}};
253   FCmp32Libcalls[CmpInst::FCMP_UNO] = {
254       {RTLIB::UO_F32, CmpInst::BAD_ICMP_PREDICATE}};
255   FCmp32Libcalls[CmpInst::FCMP_ONE] = {
256       {RTLIB::OGT_F32, CmpInst::BAD_ICMP_PREDICATE},
257       {RTLIB::OLT_F32, CmpInst::BAD_ICMP_PREDICATE}};
258   FCmp32Libcalls[CmpInst::FCMP_UEQ] = {
259       {RTLIB::OEQ_F32, CmpInst::BAD_ICMP_PREDICATE},
260       {RTLIB::UO_F32, CmpInst::BAD_ICMP_PREDICATE}};
261 
262   FCmp64Libcalls.resize(CmpInst::LAST_FCMP_PREDICATE + 1);
263   FCmp64Libcalls[CmpInst::FCMP_OEQ] = {
264       {RTLIB::OEQ_F64, CmpInst::BAD_ICMP_PREDICATE}};
265   FCmp64Libcalls[CmpInst::FCMP_OGE] = {
266       {RTLIB::OGE_F64, CmpInst::BAD_ICMP_PREDICATE}};
267   FCmp64Libcalls[CmpInst::FCMP_OGT] = {
268       {RTLIB::OGT_F64, CmpInst::BAD_ICMP_PREDICATE}};
269   FCmp64Libcalls[CmpInst::FCMP_OLE] = {
270       {RTLIB::OLE_F64, CmpInst::BAD_ICMP_PREDICATE}};
271   FCmp64Libcalls[CmpInst::FCMP_OLT] = {
272       {RTLIB::OLT_F64, CmpInst::BAD_ICMP_PREDICATE}};
273   FCmp64Libcalls[CmpInst::FCMP_ORD] = {{RTLIB::UO_F64, CmpInst::ICMP_EQ}};
274   FCmp64Libcalls[CmpInst::FCMP_UGE] = {{RTLIB::OLT_F64, CmpInst::ICMP_EQ}};
275   FCmp64Libcalls[CmpInst::FCMP_UGT] = {{RTLIB::OLE_F64, CmpInst::ICMP_EQ}};
276   FCmp64Libcalls[CmpInst::FCMP_ULE] = {{RTLIB::OGT_F64, CmpInst::ICMP_EQ}};
277   FCmp64Libcalls[CmpInst::FCMP_ULT] = {{RTLIB::OGE_F64, CmpInst::ICMP_EQ}};
278   FCmp64Libcalls[CmpInst::FCMP_UNE] = {{RTLIB::UNE_F64, CmpInst::ICMP_EQ}};
279   FCmp64Libcalls[CmpInst::FCMP_UNO] = {
280       {RTLIB::UO_F64, CmpInst::BAD_ICMP_PREDICATE}};
281   FCmp64Libcalls[CmpInst::FCMP_ONE] = {
282       {RTLIB::OGT_F64, CmpInst::BAD_ICMP_PREDICATE},
283       {RTLIB::OLT_F64, CmpInst::BAD_ICMP_PREDICATE}};
284   FCmp64Libcalls[CmpInst::FCMP_UEQ] = {
285       {RTLIB::OEQ_F64, CmpInst::BAD_ICMP_PREDICATE},
286       {RTLIB::UO_F64, CmpInst::BAD_ICMP_PREDICATE}};
287 }
288 
289 void ARMLegalizerInfo::setFCmpLibcallsGNU() {
290   // FCMP_TRUE and FCMP_FALSE don't need libcalls, they should be
291   // default-initialized.
292   FCmp32Libcalls.resize(CmpInst::LAST_FCMP_PREDICATE + 1);
293   FCmp32Libcalls[CmpInst::FCMP_OEQ] = {{RTLIB::OEQ_F32, CmpInst::ICMP_EQ}};
294   FCmp32Libcalls[CmpInst::FCMP_OGE] = {{RTLIB::OGE_F32, CmpInst::ICMP_SGE}};
295   FCmp32Libcalls[CmpInst::FCMP_OGT] = {{RTLIB::OGT_F32, CmpInst::ICMP_SGT}};
296   FCmp32Libcalls[CmpInst::FCMP_OLE] = {{RTLIB::OLE_F32, CmpInst::ICMP_SLE}};
297   FCmp32Libcalls[CmpInst::FCMP_OLT] = {{RTLIB::OLT_F32, CmpInst::ICMP_SLT}};
298   FCmp32Libcalls[CmpInst::FCMP_ORD] = {{RTLIB::UO_F32, CmpInst::ICMP_EQ}};
299   FCmp32Libcalls[CmpInst::FCMP_UGE] = {{RTLIB::OLT_F32, CmpInst::ICMP_SGE}};
300   FCmp32Libcalls[CmpInst::FCMP_UGT] = {{RTLIB::OLE_F32, CmpInst::ICMP_SGT}};
301   FCmp32Libcalls[CmpInst::FCMP_ULE] = {{RTLIB::OGT_F32, CmpInst::ICMP_SLE}};
302   FCmp32Libcalls[CmpInst::FCMP_ULT] = {{RTLIB::OGE_F32, CmpInst::ICMP_SLT}};
303   FCmp32Libcalls[CmpInst::FCMP_UNE] = {{RTLIB::UNE_F32, CmpInst::ICMP_NE}};
304   FCmp32Libcalls[CmpInst::FCMP_UNO] = {{RTLIB::UO_F32, CmpInst::ICMP_NE}};
305   FCmp32Libcalls[CmpInst::FCMP_ONE] = {{RTLIB::OGT_F32, CmpInst::ICMP_SGT},
306                                        {RTLIB::OLT_F32, CmpInst::ICMP_SLT}};
307   FCmp32Libcalls[CmpInst::FCMP_UEQ] = {{RTLIB::OEQ_F32, CmpInst::ICMP_EQ},
308                                        {RTLIB::UO_F32, CmpInst::ICMP_NE}};
309 
310   FCmp64Libcalls.resize(CmpInst::LAST_FCMP_PREDICATE + 1);
311   FCmp64Libcalls[CmpInst::FCMP_OEQ] = {{RTLIB::OEQ_F64, CmpInst::ICMP_EQ}};
312   FCmp64Libcalls[CmpInst::FCMP_OGE] = {{RTLIB::OGE_F64, CmpInst::ICMP_SGE}};
313   FCmp64Libcalls[CmpInst::FCMP_OGT] = {{RTLIB::OGT_F64, CmpInst::ICMP_SGT}};
314   FCmp64Libcalls[CmpInst::FCMP_OLE] = {{RTLIB::OLE_F64, CmpInst::ICMP_SLE}};
315   FCmp64Libcalls[CmpInst::FCMP_OLT] = {{RTLIB::OLT_F64, CmpInst::ICMP_SLT}};
316   FCmp64Libcalls[CmpInst::FCMP_ORD] = {{RTLIB::UO_F64, CmpInst::ICMP_EQ}};
317   FCmp64Libcalls[CmpInst::FCMP_UGE] = {{RTLIB::OLT_F64, CmpInst::ICMP_SGE}};
318   FCmp64Libcalls[CmpInst::FCMP_UGT] = {{RTLIB::OLE_F64, CmpInst::ICMP_SGT}};
319   FCmp64Libcalls[CmpInst::FCMP_ULE] = {{RTLIB::OGT_F64, CmpInst::ICMP_SLE}};
320   FCmp64Libcalls[CmpInst::FCMP_ULT] = {{RTLIB::OGE_F64, CmpInst::ICMP_SLT}};
321   FCmp64Libcalls[CmpInst::FCMP_UNE] = {{RTLIB::UNE_F64, CmpInst::ICMP_NE}};
322   FCmp64Libcalls[CmpInst::FCMP_UNO] = {{RTLIB::UO_F64, CmpInst::ICMP_NE}};
323   FCmp64Libcalls[CmpInst::FCMP_ONE] = {{RTLIB::OGT_F64, CmpInst::ICMP_SGT},
324                                        {RTLIB::OLT_F64, CmpInst::ICMP_SLT}};
325   FCmp64Libcalls[CmpInst::FCMP_UEQ] = {{RTLIB::OEQ_F64, CmpInst::ICMP_EQ},
326                                        {RTLIB::UO_F64, CmpInst::ICMP_NE}};
327 }
328 
329 ARMLegalizerInfo::FCmpLibcallsList
330 ARMLegalizerInfo::getFCmpLibcalls(CmpInst::Predicate Predicate,
331                                   unsigned Size) const {
332   assert(CmpInst::isFPPredicate(Predicate) && "Unsupported FCmp predicate");
333   if (Size == 32)
334     return FCmp32Libcalls[Predicate];
335   if (Size == 64)
336     return FCmp64Libcalls[Predicate];
337   llvm_unreachable("Unsupported size for FCmp predicate");
338 }
339 
340 bool ARMLegalizerInfo::legalizeCustom(LegalizerHelper &Helper, MachineInstr &MI,
341                                       LostDebugLocObserver &LocObserver) const {
342   using namespace TargetOpcode;
343 
344   MachineIRBuilder &MIRBuilder = Helper.MIRBuilder;
345   MachineRegisterInfo &MRI = *MIRBuilder.getMRI();
346   LLVMContext &Ctx = MIRBuilder.getMF().getFunction().getContext();
347 
348   switch (MI.getOpcode()) {
349   default:
350     return false;
351   case G_SREM:
352   case G_UREM: {
353     Register OriginalResult = MI.getOperand(0).getReg();
354     auto Size = MRI.getType(OriginalResult).getSizeInBits();
355     if (Size != 32)
356       return false;
357 
358     auto Libcall =
359         MI.getOpcode() == G_SREM ? RTLIB::SDIVREM_I32 : RTLIB::UDIVREM_I32;
360 
361     // Our divmod libcalls return a struct containing the quotient and the
362     // remainder. Create a new, unused register for the quotient and use the
363     // destination of the original instruction for the remainder.
364     Type *ArgTy = Type::getInt32Ty(Ctx);
365     StructType *RetTy = StructType::get(Ctx, {ArgTy, ArgTy}, /* Packed */ true);
366     Register RetRegs[] = {MRI.createGenericVirtualRegister(LLT::scalar(32)),
367                           OriginalResult};
368     auto Status = createLibcall(MIRBuilder, Libcall, {RetRegs, RetTy, 0},
369                                 {{MI.getOperand(1).getReg(), ArgTy, 0},
370                                  {MI.getOperand(2).getReg(), ArgTy, 0}},
371                                 LocObserver, &MI);
372     if (Status != LegalizerHelper::Legalized)
373       return false;
374     break;
375   }
376   case G_FCMP: {
377     assert(MRI.getType(MI.getOperand(2).getReg()) ==
378                MRI.getType(MI.getOperand(3).getReg()) &&
379            "Mismatched operands for G_FCMP");
380     auto OpSize = MRI.getType(MI.getOperand(2).getReg()).getSizeInBits();
381 
382     auto OriginalResult = MI.getOperand(0).getReg();
383     auto Predicate =
384         static_cast<CmpInst::Predicate>(MI.getOperand(1).getPredicate());
385     auto Libcalls = getFCmpLibcalls(Predicate, OpSize);
386 
387     if (Libcalls.empty()) {
388       assert((Predicate == CmpInst::FCMP_TRUE ||
389               Predicate == CmpInst::FCMP_FALSE) &&
390              "Predicate needs libcalls, but none specified");
391       MIRBuilder.buildConstant(OriginalResult,
392                                Predicate == CmpInst::FCMP_TRUE ? 1 : 0);
393       MI.eraseFromParent();
394       return true;
395     }
396 
397     assert((OpSize == 32 || OpSize == 64) && "Unsupported operand size");
398     auto *ArgTy = OpSize == 32 ? Type::getFloatTy(Ctx) : Type::getDoubleTy(Ctx);
399     auto *RetTy = Type::getInt32Ty(Ctx);
400 
401     SmallVector<Register, 2> Results;
402     for (auto Libcall : Libcalls) {
403       auto LibcallResult = MRI.createGenericVirtualRegister(LLT::scalar(32));
404       auto Status = createLibcall(MIRBuilder, Libcall.LibcallID,
405                                   {LibcallResult, RetTy, 0},
406                                   {{MI.getOperand(2).getReg(), ArgTy, 0},
407                                    {MI.getOperand(3).getReg(), ArgTy, 0}},
408                                   LocObserver, &MI);
409 
410       if (Status != LegalizerHelper::Legalized)
411         return false;
412 
413       auto ProcessedResult =
414           Libcalls.size() == 1
415               ? OriginalResult
416               : MRI.createGenericVirtualRegister(MRI.getType(OriginalResult));
417 
418       // We have a result, but we need to transform it into a proper 1-bit 0 or
419       // 1, taking into account the different peculiarities of the values
420       // returned by the comparison functions.
421       CmpInst::Predicate ResultPred = Libcall.Predicate;
422       if (ResultPred == CmpInst::BAD_ICMP_PREDICATE) {
423         // We have a nice 0 or 1, and we just need to truncate it back to 1 bit
424         // to keep the types consistent.
425         MIRBuilder.buildTrunc(ProcessedResult, LibcallResult);
426       } else {
427         // We need to compare against 0.
428         assert(CmpInst::isIntPredicate(ResultPred) && "Unsupported predicate");
429         auto Zero = MIRBuilder.buildConstant(LLT::scalar(32), 0);
430         MIRBuilder.buildICmp(ResultPred, ProcessedResult, LibcallResult, Zero);
431       }
432       Results.push_back(ProcessedResult);
433     }
434 
435     if (Results.size() != 1) {
436       assert(Results.size() == 2 && "Unexpected number of results");
437       MIRBuilder.buildOr(OriginalResult, Results[0], Results[1]);
438     }
439     break;
440   }
441   case G_CONSTANT: {
442     const ConstantInt *ConstVal = MI.getOperand(1).getCImm();
443     uint64_t ImmVal = ConstVal->getZExtValue();
444     if (ConstantMaterializationCost(ImmVal, &ST) > 2 && !ST.genExecuteOnly())
445       return Helper.lowerConstant(MI) == LegalizerHelper::Legalized;
446     return true;
447   }
448   case G_FCONSTANT: {
449     // Convert to integer constants, while preserving the binary representation.
450     auto AsInteger =
451         MI.getOperand(1).getFPImm()->getValueAPF().bitcastToAPInt();
452     MIRBuilder.buildConstant(MI.getOperand(0),
453                              *ConstantInt::get(Ctx, AsInteger));
454     break;
455   }
456   case G_SET_FPMODE: {
457     // New FPSCR = (FPSCR & FPStatusBits) | (Modes & ~FPStatusBits)
458     LLT FPEnvTy = LLT::scalar(32);
459     auto FPEnv = MRI.createGenericVirtualRegister(FPEnvTy);
460     Register Modes = MI.getOperand(0).getReg();
461     MIRBuilder.buildGetFPEnv(FPEnv);
462     auto StatusBitMask = MIRBuilder.buildConstant(FPEnvTy, ARM::FPStatusBits);
463     auto StatusBits = MIRBuilder.buildAnd(FPEnvTy, FPEnv, StatusBitMask);
464     auto NotStatusBitMask =
465         MIRBuilder.buildConstant(FPEnvTy, ~ARM::FPStatusBits);
466     auto FPModeBits = MIRBuilder.buildAnd(FPEnvTy, Modes, NotStatusBitMask);
467     auto NewFPSCR = MIRBuilder.buildOr(FPEnvTy, StatusBits, FPModeBits);
468     MIRBuilder.buildSetFPEnv(NewFPSCR);
469     break;
470   }
471   case G_RESET_FPMODE: {
472     // To get the default FP mode all control bits are cleared:
473     // FPSCR = FPSCR & (FPStatusBits | FPReservedBits)
474     LLT FPEnvTy = LLT::scalar(32);
475     auto FPEnv = MIRBuilder.buildGetFPEnv(FPEnvTy);
476     auto NotModeBitMask = MIRBuilder.buildConstant(
477         FPEnvTy, ARM::FPStatusBits | ARM::FPReservedBits);
478     auto NewFPSCR = MIRBuilder.buildAnd(FPEnvTy, FPEnv, NotModeBitMask);
479     MIRBuilder.buildSetFPEnv(NewFPSCR);
480     break;
481   }
482   }
483 
484   MI.eraseFromParent();
485   return true;
486 }
487