xref: /freebsd/contrib/llvm-project/llvm/lib/Target/ARM/ARMLegalizerInfo.cpp (revision c8e7f78a3d28ff6e6223ed136ada8e1e2f34965e)
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 /// FIXME: The following static functions are SizeChangeStrategy functions
29 /// that are meant to temporarily mimic the behaviour of the old legalization
30 /// based on doubling/halving non-legal types as closely as possible. This is
31 /// not entirly possible as only legalizing the types that are exactly a power
32 /// of 2 times the size of the legal types would require specifying all those
33 /// sizes explicitly.
34 /// In practice, not specifying those isn't a problem, and the below functions
35 /// should disappear quickly as we add support for legalizing non-power-of-2
36 /// sized types further.
37 static void addAndInterleaveWithUnsupported(
38     LegacyLegalizerInfo::SizeAndActionsVec &result,
39     const LegacyLegalizerInfo::SizeAndActionsVec &v) {
40   for (unsigned i = 0; i < v.size(); ++i) {
41     result.push_back(v[i]);
42     if (i + 1 < v[i].first && i + 1 < v.size() &&
43         v[i + 1].first != v[i].first + 1)
44       result.push_back({v[i].first + 1, LegacyLegalizeActions::Unsupported});
45   }
46 }
47 
48 static LegacyLegalizerInfo::SizeAndActionsVec
49 widen_8_16(const LegacyLegalizerInfo::SizeAndActionsVec &v) {
50   assert(v.size() >= 1);
51   assert(v[0].first > 17);
52   LegacyLegalizerInfo::SizeAndActionsVec result = {
53       {1, LegacyLegalizeActions::Unsupported},
54       {8, LegacyLegalizeActions::WidenScalar},
55       {9, LegacyLegalizeActions::Unsupported},
56       {16, LegacyLegalizeActions::WidenScalar},
57       {17, LegacyLegalizeActions::Unsupported}};
58   addAndInterleaveWithUnsupported(result, v);
59   auto Largest = result.back().first;
60   result.push_back({Largest + 1, LegacyLegalizeActions::Unsupported});
61   return result;
62 }
63 
64 static bool AEABI(const ARMSubtarget &ST) {
65   return ST.isTargetAEABI() || ST.isTargetGNUAEABI() || ST.isTargetMuslAEABI();
66 }
67 
68 ARMLegalizerInfo::ARMLegalizerInfo(const ARMSubtarget &ST) {
69   using namespace TargetOpcode;
70 
71   const LLT p0 = LLT::pointer(0, 32);
72 
73   const LLT s1 = LLT::scalar(1);
74   const LLT s8 = LLT::scalar(8);
75   const LLT s16 = LLT::scalar(16);
76   const LLT s32 = LLT::scalar(32);
77   const LLT s64 = LLT::scalar(64);
78 
79   auto &LegacyInfo = getLegacyLegalizerInfo();
80   if (ST.isThumb1Only()) {
81     // Thumb1 is not supported yet.
82     LegacyInfo.computeTables();
83     verify(*ST.getInstrInfo());
84     return;
85   }
86 
87   getActionDefinitionsBuilder({G_SEXT, G_ZEXT, G_ANYEXT})
88       .legalForCartesianProduct({s8, s16, s32}, {s1, s8, s16});
89 
90   getActionDefinitionsBuilder(G_SEXT_INREG).lower();
91 
92   getActionDefinitionsBuilder({G_MUL, G_AND, G_OR, G_XOR})
93       .legalFor({s32})
94       .clampScalar(0, s32, s32);
95 
96   if (ST.hasNEON())
97     getActionDefinitionsBuilder({G_ADD, G_SUB})
98         .legalFor({s32, s64})
99         .minScalar(0, s32);
100   else
101     getActionDefinitionsBuilder({G_ADD, G_SUB})
102         .legalFor({s32})
103         .minScalar(0, s32);
104 
105   getActionDefinitionsBuilder({G_ASHR, G_LSHR, G_SHL})
106     .legalFor({{s32, s32}})
107     .minScalar(0, s32)
108     .clampScalar(1, s32, s32);
109 
110   bool HasHWDivide = (!ST.isThumb() && ST.hasDivideInARMMode()) ||
111                      (ST.isThumb() && ST.hasDivideInThumbMode());
112   if (HasHWDivide)
113     getActionDefinitionsBuilder({G_SDIV, G_UDIV})
114         .legalFor({s32})
115         .clampScalar(0, s32, s32);
116   else
117     getActionDefinitionsBuilder({G_SDIV, G_UDIV})
118         .libcallFor({s32})
119         .clampScalar(0, s32, s32);
120 
121   for (unsigned Op : {G_SREM, G_UREM}) {
122     LegacyInfo.setLegalizeScalarToDifferentSizeStrategy(Op, 0, widen_8_16);
123     if (HasHWDivide)
124       LegacyInfo.setAction({Op, s32}, LegacyLegalizeActions::Lower);
125     else if (AEABI(ST))
126       LegacyInfo.setAction({Op, s32}, LegacyLegalizeActions::Custom);
127     else
128       LegacyInfo.setAction({Op, s32}, LegacyLegalizeActions::Libcall);
129   }
130 
131   getActionDefinitionsBuilder(G_INTTOPTR)
132       .legalFor({{p0, s32}})
133       .minScalar(1, s32);
134   getActionDefinitionsBuilder(G_PTRTOINT)
135       .legalFor({{s32, p0}})
136       .minScalar(0, s32);
137 
138   getActionDefinitionsBuilder(G_CONSTANT)
139       .legalFor({s32, p0})
140       .clampScalar(0, s32, s32);
141 
142   getActionDefinitionsBuilder(G_ICMP)
143       .legalForCartesianProduct({s1}, {s32, p0})
144       .minScalar(1, s32);
145 
146   getActionDefinitionsBuilder(G_SELECT)
147       .legalForCartesianProduct({s32, p0}, {s1})
148       .minScalar(0, s32);
149 
150   // We're keeping these builders around because we'll want to add support for
151   // floating point to them.
152   auto &LoadStoreBuilder = getActionDefinitionsBuilder({G_LOAD, G_STORE})
153                                .legalForTypesWithMemDesc({{s8, p0, s8, 8},
154                                                           {s16, p0, s16, 8},
155                                                           {s32, p0, s32, 8},
156                                                           {p0, p0, p0, 8}})
157                                .unsupportedIfMemSizeNotPow2();
158 
159   getActionDefinitionsBuilder(G_FRAME_INDEX).legalFor({p0});
160   getActionDefinitionsBuilder(G_GLOBAL_VALUE).legalFor({p0});
161 
162   auto &PhiBuilder =
163       getActionDefinitionsBuilder(G_PHI)
164           .legalFor({s32, p0})
165           .minScalar(0, s32);
166 
167   getActionDefinitionsBuilder(G_PTR_ADD)
168       .legalFor({{p0, s32}})
169       .minScalar(1, s32);
170 
171   getActionDefinitionsBuilder(G_BRCOND).legalFor({s1});
172 
173   if (!ST.useSoftFloat() && ST.hasVFP2Base()) {
174     getActionDefinitionsBuilder(
175         {G_FADD, G_FSUB, G_FMUL, G_FDIV, G_FCONSTANT, G_FNEG})
176         .legalFor({s32, s64});
177 
178     LoadStoreBuilder
179         .legalForTypesWithMemDesc({{s64, p0, s64, 32}})
180         .maxScalar(0, s32);
181     PhiBuilder.legalFor({s64});
182 
183     getActionDefinitionsBuilder(G_FCMP).legalForCartesianProduct({s1},
184                                                                  {s32, s64});
185 
186     getActionDefinitionsBuilder(G_MERGE_VALUES).legalFor({{s64, s32}});
187     getActionDefinitionsBuilder(G_UNMERGE_VALUES).legalFor({{s32, s64}});
188 
189     getActionDefinitionsBuilder(G_FPEXT).legalFor({{s64, s32}});
190     getActionDefinitionsBuilder(G_FPTRUNC).legalFor({{s32, s64}});
191 
192     getActionDefinitionsBuilder({G_FPTOSI, G_FPTOUI})
193         .legalForCartesianProduct({s32}, {s32, s64});
194     getActionDefinitionsBuilder({G_SITOFP, G_UITOFP})
195         .legalForCartesianProduct({s32, s64}, {s32});
196   } else {
197     getActionDefinitionsBuilder({G_FADD, G_FSUB, G_FMUL, G_FDIV})
198         .libcallFor({s32, s64});
199 
200     LoadStoreBuilder.maxScalar(0, s32);
201 
202     for (auto Ty : {s32, s64})
203       LegacyInfo.setAction({G_FNEG, Ty}, LegacyLegalizeActions::Lower);
204 
205     getActionDefinitionsBuilder(G_FCONSTANT).customFor({s32, s64});
206 
207     getActionDefinitionsBuilder(G_FCMP).customForCartesianProduct({s1},
208                                                                   {s32, s64});
209 
210     if (AEABI(ST))
211       setFCmpLibcallsAEABI();
212     else
213       setFCmpLibcallsGNU();
214 
215     getActionDefinitionsBuilder(G_FPEXT).libcallFor({{s64, s32}});
216     getActionDefinitionsBuilder(G_FPTRUNC).libcallFor({{s32, s64}});
217 
218     getActionDefinitionsBuilder({G_FPTOSI, G_FPTOUI})
219         .libcallForCartesianProduct({s32}, {s32, s64});
220     getActionDefinitionsBuilder({G_SITOFP, G_UITOFP})
221         .libcallForCartesianProduct({s32, s64}, {s32});
222   }
223 
224   // Just expand whatever loads and stores are left.
225   LoadStoreBuilder.lower();
226 
227   if (!ST.useSoftFloat() && ST.hasVFP4Base())
228     getActionDefinitionsBuilder(G_FMA).legalFor({s32, s64});
229   else
230     getActionDefinitionsBuilder(G_FMA).libcallFor({s32, s64});
231 
232   getActionDefinitionsBuilder({G_FREM, G_FPOW}).libcallFor({s32, s64});
233 
234   if (ST.hasV5TOps()) {
235     getActionDefinitionsBuilder(G_CTLZ)
236         .legalFor({s32, s32})
237         .clampScalar(1, s32, s32)
238         .clampScalar(0, s32, s32);
239     getActionDefinitionsBuilder(G_CTLZ_ZERO_UNDEF)
240         .lowerFor({s32, s32})
241         .clampScalar(1, s32, s32)
242         .clampScalar(0, s32, s32);
243   } else {
244     getActionDefinitionsBuilder(G_CTLZ_ZERO_UNDEF)
245         .libcallFor({s32, s32})
246         .clampScalar(1, s32, s32)
247         .clampScalar(0, s32, s32);
248     getActionDefinitionsBuilder(G_CTLZ)
249         .lowerFor({s32, s32})
250         .clampScalar(1, s32, s32)
251         .clampScalar(0, s32, s32);
252   }
253 
254   LegacyInfo.computeTables();
255   verify(*ST.getInstrInfo());
256 }
257 
258 void ARMLegalizerInfo::setFCmpLibcallsAEABI() {
259   // FCMP_TRUE and FCMP_FALSE don't need libcalls, they should be
260   // default-initialized.
261   FCmp32Libcalls.resize(CmpInst::LAST_FCMP_PREDICATE + 1);
262   FCmp32Libcalls[CmpInst::FCMP_OEQ] = {
263       {RTLIB::OEQ_F32, CmpInst::BAD_ICMP_PREDICATE}};
264   FCmp32Libcalls[CmpInst::FCMP_OGE] = {
265       {RTLIB::OGE_F32, CmpInst::BAD_ICMP_PREDICATE}};
266   FCmp32Libcalls[CmpInst::FCMP_OGT] = {
267       {RTLIB::OGT_F32, CmpInst::BAD_ICMP_PREDICATE}};
268   FCmp32Libcalls[CmpInst::FCMP_OLE] = {
269       {RTLIB::OLE_F32, CmpInst::BAD_ICMP_PREDICATE}};
270   FCmp32Libcalls[CmpInst::FCMP_OLT] = {
271       {RTLIB::OLT_F32, CmpInst::BAD_ICMP_PREDICATE}};
272   FCmp32Libcalls[CmpInst::FCMP_ORD] = {{RTLIB::UO_F32, CmpInst::ICMP_EQ}};
273   FCmp32Libcalls[CmpInst::FCMP_UGE] = {{RTLIB::OLT_F32, CmpInst::ICMP_EQ}};
274   FCmp32Libcalls[CmpInst::FCMP_UGT] = {{RTLIB::OLE_F32, CmpInst::ICMP_EQ}};
275   FCmp32Libcalls[CmpInst::FCMP_ULE] = {{RTLIB::OGT_F32, CmpInst::ICMP_EQ}};
276   FCmp32Libcalls[CmpInst::FCMP_ULT] = {{RTLIB::OGE_F32, CmpInst::ICMP_EQ}};
277   FCmp32Libcalls[CmpInst::FCMP_UNE] = {{RTLIB::UNE_F32, CmpInst::ICMP_EQ}};
278   FCmp32Libcalls[CmpInst::FCMP_UNO] = {
279       {RTLIB::UO_F32, CmpInst::BAD_ICMP_PREDICATE}};
280   FCmp32Libcalls[CmpInst::FCMP_ONE] = {
281       {RTLIB::OGT_F32, CmpInst::BAD_ICMP_PREDICATE},
282       {RTLIB::OLT_F32, CmpInst::BAD_ICMP_PREDICATE}};
283   FCmp32Libcalls[CmpInst::FCMP_UEQ] = {
284       {RTLIB::OEQ_F32, CmpInst::BAD_ICMP_PREDICATE},
285       {RTLIB::UO_F32, CmpInst::BAD_ICMP_PREDICATE}};
286 
287   FCmp64Libcalls.resize(CmpInst::LAST_FCMP_PREDICATE + 1);
288   FCmp64Libcalls[CmpInst::FCMP_OEQ] = {
289       {RTLIB::OEQ_F64, CmpInst::BAD_ICMP_PREDICATE}};
290   FCmp64Libcalls[CmpInst::FCMP_OGE] = {
291       {RTLIB::OGE_F64, CmpInst::BAD_ICMP_PREDICATE}};
292   FCmp64Libcalls[CmpInst::FCMP_OGT] = {
293       {RTLIB::OGT_F64, CmpInst::BAD_ICMP_PREDICATE}};
294   FCmp64Libcalls[CmpInst::FCMP_OLE] = {
295       {RTLIB::OLE_F64, CmpInst::BAD_ICMP_PREDICATE}};
296   FCmp64Libcalls[CmpInst::FCMP_OLT] = {
297       {RTLIB::OLT_F64, CmpInst::BAD_ICMP_PREDICATE}};
298   FCmp64Libcalls[CmpInst::FCMP_ORD] = {{RTLIB::UO_F64, CmpInst::ICMP_EQ}};
299   FCmp64Libcalls[CmpInst::FCMP_UGE] = {{RTLIB::OLT_F64, CmpInst::ICMP_EQ}};
300   FCmp64Libcalls[CmpInst::FCMP_UGT] = {{RTLIB::OLE_F64, CmpInst::ICMP_EQ}};
301   FCmp64Libcalls[CmpInst::FCMP_ULE] = {{RTLIB::OGT_F64, CmpInst::ICMP_EQ}};
302   FCmp64Libcalls[CmpInst::FCMP_ULT] = {{RTLIB::OGE_F64, CmpInst::ICMP_EQ}};
303   FCmp64Libcalls[CmpInst::FCMP_UNE] = {{RTLIB::UNE_F64, CmpInst::ICMP_EQ}};
304   FCmp64Libcalls[CmpInst::FCMP_UNO] = {
305       {RTLIB::UO_F64, CmpInst::BAD_ICMP_PREDICATE}};
306   FCmp64Libcalls[CmpInst::FCMP_ONE] = {
307       {RTLIB::OGT_F64, CmpInst::BAD_ICMP_PREDICATE},
308       {RTLIB::OLT_F64, CmpInst::BAD_ICMP_PREDICATE}};
309   FCmp64Libcalls[CmpInst::FCMP_UEQ] = {
310       {RTLIB::OEQ_F64, CmpInst::BAD_ICMP_PREDICATE},
311       {RTLIB::UO_F64, CmpInst::BAD_ICMP_PREDICATE}};
312 }
313 
314 void ARMLegalizerInfo::setFCmpLibcallsGNU() {
315   // FCMP_TRUE and FCMP_FALSE don't need libcalls, they should be
316   // default-initialized.
317   FCmp32Libcalls.resize(CmpInst::LAST_FCMP_PREDICATE + 1);
318   FCmp32Libcalls[CmpInst::FCMP_OEQ] = {{RTLIB::OEQ_F32, CmpInst::ICMP_EQ}};
319   FCmp32Libcalls[CmpInst::FCMP_OGE] = {{RTLIB::OGE_F32, CmpInst::ICMP_SGE}};
320   FCmp32Libcalls[CmpInst::FCMP_OGT] = {{RTLIB::OGT_F32, CmpInst::ICMP_SGT}};
321   FCmp32Libcalls[CmpInst::FCMP_OLE] = {{RTLIB::OLE_F32, CmpInst::ICMP_SLE}};
322   FCmp32Libcalls[CmpInst::FCMP_OLT] = {{RTLIB::OLT_F32, CmpInst::ICMP_SLT}};
323   FCmp32Libcalls[CmpInst::FCMP_ORD] = {{RTLIB::UO_F32, CmpInst::ICMP_EQ}};
324   FCmp32Libcalls[CmpInst::FCMP_UGE] = {{RTLIB::OLT_F32, CmpInst::ICMP_SGE}};
325   FCmp32Libcalls[CmpInst::FCMP_UGT] = {{RTLIB::OLE_F32, CmpInst::ICMP_SGT}};
326   FCmp32Libcalls[CmpInst::FCMP_ULE] = {{RTLIB::OGT_F32, CmpInst::ICMP_SLE}};
327   FCmp32Libcalls[CmpInst::FCMP_ULT] = {{RTLIB::OGE_F32, CmpInst::ICMP_SLT}};
328   FCmp32Libcalls[CmpInst::FCMP_UNE] = {{RTLIB::UNE_F32, CmpInst::ICMP_NE}};
329   FCmp32Libcalls[CmpInst::FCMP_UNO] = {{RTLIB::UO_F32, CmpInst::ICMP_NE}};
330   FCmp32Libcalls[CmpInst::FCMP_ONE] = {{RTLIB::OGT_F32, CmpInst::ICMP_SGT},
331                                        {RTLIB::OLT_F32, CmpInst::ICMP_SLT}};
332   FCmp32Libcalls[CmpInst::FCMP_UEQ] = {{RTLIB::OEQ_F32, CmpInst::ICMP_EQ},
333                                        {RTLIB::UO_F32, CmpInst::ICMP_NE}};
334 
335   FCmp64Libcalls.resize(CmpInst::LAST_FCMP_PREDICATE + 1);
336   FCmp64Libcalls[CmpInst::FCMP_OEQ] = {{RTLIB::OEQ_F64, CmpInst::ICMP_EQ}};
337   FCmp64Libcalls[CmpInst::FCMP_OGE] = {{RTLIB::OGE_F64, CmpInst::ICMP_SGE}};
338   FCmp64Libcalls[CmpInst::FCMP_OGT] = {{RTLIB::OGT_F64, CmpInst::ICMP_SGT}};
339   FCmp64Libcalls[CmpInst::FCMP_OLE] = {{RTLIB::OLE_F64, CmpInst::ICMP_SLE}};
340   FCmp64Libcalls[CmpInst::FCMP_OLT] = {{RTLIB::OLT_F64, CmpInst::ICMP_SLT}};
341   FCmp64Libcalls[CmpInst::FCMP_ORD] = {{RTLIB::UO_F64, CmpInst::ICMP_EQ}};
342   FCmp64Libcalls[CmpInst::FCMP_UGE] = {{RTLIB::OLT_F64, CmpInst::ICMP_SGE}};
343   FCmp64Libcalls[CmpInst::FCMP_UGT] = {{RTLIB::OLE_F64, CmpInst::ICMP_SGT}};
344   FCmp64Libcalls[CmpInst::FCMP_ULE] = {{RTLIB::OGT_F64, CmpInst::ICMP_SLE}};
345   FCmp64Libcalls[CmpInst::FCMP_ULT] = {{RTLIB::OGE_F64, CmpInst::ICMP_SLT}};
346   FCmp64Libcalls[CmpInst::FCMP_UNE] = {{RTLIB::UNE_F64, CmpInst::ICMP_NE}};
347   FCmp64Libcalls[CmpInst::FCMP_UNO] = {{RTLIB::UO_F64, CmpInst::ICMP_NE}};
348   FCmp64Libcalls[CmpInst::FCMP_ONE] = {{RTLIB::OGT_F64, CmpInst::ICMP_SGT},
349                                        {RTLIB::OLT_F64, CmpInst::ICMP_SLT}};
350   FCmp64Libcalls[CmpInst::FCMP_UEQ] = {{RTLIB::OEQ_F64, CmpInst::ICMP_EQ},
351                                        {RTLIB::UO_F64, CmpInst::ICMP_NE}};
352 }
353 
354 ARMLegalizerInfo::FCmpLibcallsList
355 ARMLegalizerInfo::getFCmpLibcalls(CmpInst::Predicate Predicate,
356                                   unsigned Size) const {
357   assert(CmpInst::isFPPredicate(Predicate) && "Unsupported FCmp predicate");
358   if (Size == 32)
359     return FCmp32Libcalls[Predicate];
360   if (Size == 64)
361     return FCmp64Libcalls[Predicate];
362   llvm_unreachable("Unsupported size for FCmp predicate");
363 }
364 
365 bool ARMLegalizerInfo::legalizeCustom(LegalizerHelper &Helper,
366                                       MachineInstr &MI) const {
367   using namespace TargetOpcode;
368 
369   MachineIRBuilder &MIRBuilder = Helper.MIRBuilder;
370   MachineRegisterInfo &MRI = *MIRBuilder.getMRI();
371   LLVMContext &Ctx = MIRBuilder.getMF().getFunction().getContext();
372 
373   switch (MI.getOpcode()) {
374   default:
375     return false;
376   case G_SREM:
377   case G_UREM: {
378     Register OriginalResult = MI.getOperand(0).getReg();
379     auto Size = MRI.getType(OriginalResult).getSizeInBits();
380     if (Size != 32)
381       return false;
382 
383     auto Libcall =
384         MI.getOpcode() == G_SREM ? RTLIB::SDIVREM_I32 : RTLIB::UDIVREM_I32;
385 
386     // Our divmod libcalls return a struct containing the quotient and the
387     // remainder. Create a new, unused register for the quotient and use the
388     // destination of the original instruction for the remainder.
389     Type *ArgTy = Type::getInt32Ty(Ctx);
390     StructType *RetTy = StructType::get(Ctx, {ArgTy, ArgTy}, /* Packed */ true);
391     Register RetRegs[] = {MRI.createGenericVirtualRegister(LLT::scalar(32)),
392                           OriginalResult};
393     auto Status = createLibcall(MIRBuilder, Libcall, {RetRegs, RetTy, 0},
394                                 {{MI.getOperand(1).getReg(), ArgTy, 0},
395                                  {MI.getOperand(2).getReg(), ArgTy, 0}});
396     if (Status != LegalizerHelper::Legalized)
397       return false;
398     break;
399   }
400   case G_FCMP: {
401     assert(MRI.getType(MI.getOperand(2).getReg()) ==
402                MRI.getType(MI.getOperand(3).getReg()) &&
403            "Mismatched operands for G_FCMP");
404     auto OpSize = MRI.getType(MI.getOperand(2).getReg()).getSizeInBits();
405 
406     auto OriginalResult = MI.getOperand(0).getReg();
407     auto Predicate =
408         static_cast<CmpInst::Predicate>(MI.getOperand(1).getPredicate());
409     auto Libcalls = getFCmpLibcalls(Predicate, OpSize);
410 
411     if (Libcalls.empty()) {
412       assert((Predicate == CmpInst::FCMP_TRUE ||
413               Predicate == CmpInst::FCMP_FALSE) &&
414              "Predicate needs libcalls, but none specified");
415       MIRBuilder.buildConstant(OriginalResult,
416                                Predicate == CmpInst::FCMP_TRUE ? 1 : 0);
417       MI.eraseFromParent();
418       return true;
419     }
420 
421     assert((OpSize == 32 || OpSize == 64) && "Unsupported operand size");
422     auto *ArgTy = OpSize == 32 ? Type::getFloatTy(Ctx) : Type::getDoubleTy(Ctx);
423     auto *RetTy = Type::getInt32Ty(Ctx);
424 
425     SmallVector<Register, 2> Results;
426     for (auto Libcall : Libcalls) {
427       auto LibcallResult = MRI.createGenericVirtualRegister(LLT::scalar(32));
428       auto Status = createLibcall(MIRBuilder, Libcall.LibcallID,
429                                   {LibcallResult, RetTy, 0},
430                                   {{MI.getOperand(2).getReg(), ArgTy, 0},
431                                    {MI.getOperand(3).getReg(), ArgTy, 0}});
432 
433       if (Status != LegalizerHelper::Legalized)
434         return false;
435 
436       auto ProcessedResult =
437           Libcalls.size() == 1
438               ? OriginalResult
439               : MRI.createGenericVirtualRegister(MRI.getType(OriginalResult));
440 
441       // We have a result, but we need to transform it into a proper 1-bit 0 or
442       // 1, taking into account the different peculiarities of the values
443       // returned by the comparison functions.
444       CmpInst::Predicate ResultPred = Libcall.Predicate;
445       if (ResultPred == CmpInst::BAD_ICMP_PREDICATE) {
446         // We have a nice 0 or 1, and we just need to truncate it back to 1 bit
447         // to keep the types consistent.
448         MIRBuilder.buildTrunc(ProcessedResult, LibcallResult);
449       } else {
450         // We need to compare against 0.
451         assert(CmpInst::isIntPredicate(ResultPred) && "Unsupported predicate");
452         auto Zero = MIRBuilder.buildConstant(LLT::scalar(32), 0);
453         MIRBuilder.buildICmp(ResultPred, ProcessedResult, LibcallResult, Zero);
454       }
455       Results.push_back(ProcessedResult);
456     }
457 
458     if (Results.size() != 1) {
459       assert(Results.size() == 2 && "Unexpected number of results");
460       MIRBuilder.buildOr(OriginalResult, Results[0], Results[1]);
461     }
462     break;
463   }
464   case G_FCONSTANT: {
465     // Convert to integer constants, while preserving the binary representation.
466     auto AsInteger =
467         MI.getOperand(1).getFPImm()->getValueAPF().bitcastToAPInt();
468     MIRBuilder.buildConstant(MI.getOperand(0),
469                              *ConstantInt::get(Ctx, AsInteger));
470     break;
471   }
472   }
473 
474   MI.eraseFromParent();
475   return true;
476 }
477