xref: /llvm-project/llvm/lib/Target/ARM/ARMLegalizerInfo.cpp (revision aaac268285ff596b4cbffbb1ce8dbe516811eda8)
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/LowLevelType.h"
18 #include "llvm/CodeGen/MachineRegisterInfo.h"
19 #include "llvm/CodeGen/TargetOpcodes.h"
20 #include "llvm/CodeGen/ValueTypes.h"
21 #include "llvm/IR/DerivedTypes.h"
22 #include "llvm/IR/Type.h"
23 
24 using namespace llvm;
25 using namespace LegalizeActions;
26 
27 /// FIXME: The following static functions are SizeChangeStrategy functions
28 /// that are meant to temporarily mimic the behaviour of the old legalization
29 /// based on doubling/halving non-legal types as closely as possible. This is
30 /// not entirly possible as only legalizing the types that are exactly a power
31 /// of 2 times the size of the legal types would require specifying all those
32 /// sizes explicitly.
33 /// In practice, not specifying those isn't a problem, and the below functions
34 /// should disappear quickly as we add support for legalizing non-power-of-2
35 /// sized types further.
36 static void addAndInterleaveWithUnsupported(
37     LegacyLegalizerInfo::SizeAndActionsVec &result,
38     const LegacyLegalizerInfo::SizeAndActionsVec &v) {
39   for (unsigned i = 0; i < v.size(); ++i) {
40     result.push_back(v[i]);
41     if (i + 1 < v[i].first && i + 1 < v.size() &&
42         v[i + 1].first != v[i].first + 1)
43       result.push_back({v[i].first + 1, LegacyLegalizeActions::Unsupported});
44   }
45 }
46 
47 static LegacyLegalizerInfo::SizeAndActionsVec
48 widen_8_16(const LegacyLegalizerInfo::SizeAndActionsVec &v) {
49   assert(v.size() >= 1);
50   assert(v[0].first > 17);
51   LegacyLegalizerInfo::SizeAndActionsVec result = {
52       {1, LegacyLegalizeActions::Unsupported},
53       {8, LegacyLegalizeActions::WidenScalar},
54       {9, LegacyLegalizeActions::Unsupported},
55       {16, LegacyLegalizeActions::WidenScalar},
56       {17, LegacyLegalizeActions::Unsupported}};
57   addAndInterleaveWithUnsupported(result, v);
58   auto Largest = result.back().first;
59   result.push_back({Largest + 1, LegacyLegalizeActions::Unsupported});
60   return result;
61 }
62 
63 static bool AEABI(const ARMSubtarget &ST) {
64   return ST.isTargetAEABI() || ST.isTargetGNUAEABI() || ST.isTargetMuslAEABI();
65 }
66 
67 ARMLegalizerInfo::ARMLegalizerInfo(const ARMSubtarget &ST) {
68   using namespace TargetOpcode;
69 
70   const LLT p0 = LLT::pointer(0, 32);
71 
72   const LLT s1 = LLT::scalar(1);
73   const LLT s8 = LLT::scalar(8);
74   const LLT s16 = LLT::scalar(16);
75   const LLT s32 = LLT::scalar(32);
76   const LLT s64 = LLT::scalar(64);
77 
78   auto &LegacyInfo = getLegacyLegalizerInfo();
79   if (ST.isThumb1Only()) {
80     // Thumb1 is not supported yet.
81     LegacyInfo.computeTables();
82     verify(*ST.getInstrInfo());
83     return;
84   }
85 
86   getActionDefinitionsBuilder({G_SEXT, G_ZEXT, G_ANYEXT})
87       .legalForCartesianProduct({s8, s16, s32}, {s1, s8, s16});
88 
89   getActionDefinitionsBuilder(G_SEXT_INREG).lower();
90 
91   getActionDefinitionsBuilder({G_MUL, G_AND, G_OR, G_XOR})
92       .legalFor({s32})
93       .clampScalar(0, s32, s32);
94 
95   if (ST.hasNEON())
96     getActionDefinitionsBuilder({G_ADD, G_SUB})
97         .legalFor({s32, s64})
98         .minScalar(0, s32);
99   else
100     getActionDefinitionsBuilder({G_ADD, G_SUB})
101         .legalFor({s32})
102         .minScalar(0, s32);
103 
104   getActionDefinitionsBuilder({G_ASHR, G_LSHR, G_SHL})
105     .legalFor({{s32, s32}})
106     .minScalar(0, s32)
107     .clampScalar(1, s32, s32);
108 
109   bool HasHWDivide = (!ST.isThumb() && ST.hasDivideInARMMode()) ||
110                      (ST.isThumb() && ST.hasDivideInThumbMode());
111   if (HasHWDivide)
112     getActionDefinitionsBuilder({G_SDIV, G_UDIV})
113         .legalFor({s32})
114         .clampScalar(0, s32, s32);
115   else
116     getActionDefinitionsBuilder({G_SDIV, G_UDIV})
117         .libcallFor({s32})
118         .clampScalar(0, s32, s32);
119 
120   for (unsigned Op : {G_SREM, G_UREM}) {
121     LegacyInfo.setLegalizeScalarToDifferentSizeStrategy(Op, 0, widen_8_16);
122     if (HasHWDivide)
123       LegacyInfo.setAction({Op, s32}, LegacyLegalizeActions::Lower);
124     else if (AEABI(ST))
125       LegacyInfo.setAction({Op, s32}, LegacyLegalizeActions::Custom);
126     else
127       LegacyInfo.setAction({Op, s32}, LegacyLegalizeActions::Libcall);
128   }
129 
130   getActionDefinitionsBuilder(G_INTTOPTR)
131       .legalFor({{p0, s32}})
132       .minScalar(1, s32);
133   getActionDefinitionsBuilder(G_PTRTOINT)
134       .legalFor({{s32, p0}})
135       .minScalar(0, s32);
136 
137   getActionDefinitionsBuilder(G_CONSTANT)
138       .legalFor({s32, p0})
139       .clampScalar(0, s32, s32);
140 
141   getActionDefinitionsBuilder(G_ICMP)
142       .legalForCartesianProduct({s1}, {s32, p0})
143       .minScalar(1, s32);
144 
145   getActionDefinitionsBuilder(G_SELECT)
146       .legalForCartesianProduct({s32, p0}, {s1})
147       .minScalar(0, s32);
148 
149   // We're keeping these builders around because we'll want to add support for
150   // floating point to them.
151   auto &LoadStoreBuilder = getActionDefinitionsBuilder({G_LOAD, G_STORE})
152                                .legalForTypesWithMemDesc({{s1, p0, 8, 8},
153                                                           {s8, p0, 8, 8},
154                                                           {s16, p0, 16, 8},
155                                                           {s32, p0, 32, 8},
156                                                           {p0, p0, 32, 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, 64, 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   if (!ST.useSoftFloat() && ST.hasVFP4Base())
225     getActionDefinitionsBuilder(G_FMA).legalFor({s32, s64});
226   else
227     getActionDefinitionsBuilder(G_FMA).libcallFor({s32, s64});
228 
229   getActionDefinitionsBuilder({G_FREM, G_FPOW}).libcallFor({s32, s64});
230 
231   if (ST.hasV5TOps()) {
232     getActionDefinitionsBuilder(G_CTLZ)
233         .legalFor({s32, s32})
234         .clampScalar(1, s32, s32)
235         .clampScalar(0, s32, s32);
236     getActionDefinitionsBuilder(G_CTLZ_ZERO_UNDEF)
237         .lowerFor({s32, s32})
238         .clampScalar(1, s32, s32)
239         .clampScalar(0, s32, s32);
240   } else {
241     getActionDefinitionsBuilder(G_CTLZ_ZERO_UNDEF)
242         .libcallFor({s32, s32})
243         .clampScalar(1, s32, s32)
244         .clampScalar(0, s32, s32);
245     getActionDefinitionsBuilder(G_CTLZ)
246         .lowerFor({s32, s32})
247         .clampScalar(1, s32, s32)
248         .clampScalar(0, s32, s32);
249   }
250 
251   LegacyInfo.computeTables();
252   verify(*ST.getInstrInfo());
253 }
254 
255 void ARMLegalizerInfo::setFCmpLibcallsAEABI() {
256   // FCMP_TRUE and FCMP_FALSE don't need libcalls, they should be
257   // default-initialized.
258   FCmp32Libcalls.resize(CmpInst::LAST_FCMP_PREDICATE + 1);
259   FCmp32Libcalls[CmpInst::FCMP_OEQ] = {
260       {RTLIB::OEQ_F32, CmpInst::BAD_ICMP_PREDICATE}};
261   FCmp32Libcalls[CmpInst::FCMP_OGE] = {
262       {RTLIB::OGE_F32, CmpInst::BAD_ICMP_PREDICATE}};
263   FCmp32Libcalls[CmpInst::FCMP_OGT] = {
264       {RTLIB::OGT_F32, CmpInst::BAD_ICMP_PREDICATE}};
265   FCmp32Libcalls[CmpInst::FCMP_OLE] = {
266       {RTLIB::OLE_F32, CmpInst::BAD_ICMP_PREDICATE}};
267   FCmp32Libcalls[CmpInst::FCMP_OLT] = {
268       {RTLIB::OLT_F32, CmpInst::BAD_ICMP_PREDICATE}};
269   FCmp32Libcalls[CmpInst::FCMP_ORD] = {{RTLIB::UO_F32, CmpInst::ICMP_EQ}};
270   FCmp32Libcalls[CmpInst::FCMP_UGE] = {{RTLIB::OLT_F32, CmpInst::ICMP_EQ}};
271   FCmp32Libcalls[CmpInst::FCMP_UGT] = {{RTLIB::OLE_F32, CmpInst::ICMP_EQ}};
272   FCmp32Libcalls[CmpInst::FCMP_ULE] = {{RTLIB::OGT_F32, CmpInst::ICMP_EQ}};
273   FCmp32Libcalls[CmpInst::FCMP_ULT] = {{RTLIB::OGE_F32, CmpInst::ICMP_EQ}};
274   FCmp32Libcalls[CmpInst::FCMP_UNE] = {{RTLIB::UNE_F32, CmpInst::ICMP_EQ}};
275   FCmp32Libcalls[CmpInst::FCMP_UNO] = {
276       {RTLIB::UO_F32, CmpInst::BAD_ICMP_PREDICATE}};
277   FCmp32Libcalls[CmpInst::FCMP_ONE] = {
278       {RTLIB::OGT_F32, CmpInst::BAD_ICMP_PREDICATE},
279       {RTLIB::OLT_F32, CmpInst::BAD_ICMP_PREDICATE}};
280   FCmp32Libcalls[CmpInst::FCMP_UEQ] = {
281       {RTLIB::OEQ_F32, CmpInst::BAD_ICMP_PREDICATE},
282       {RTLIB::UO_F32, CmpInst::BAD_ICMP_PREDICATE}};
283 
284   FCmp64Libcalls.resize(CmpInst::LAST_FCMP_PREDICATE + 1);
285   FCmp64Libcalls[CmpInst::FCMP_OEQ] = {
286       {RTLIB::OEQ_F64, CmpInst::BAD_ICMP_PREDICATE}};
287   FCmp64Libcalls[CmpInst::FCMP_OGE] = {
288       {RTLIB::OGE_F64, CmpInst::BAD_ICMP_PREDICATE}};
289   FCmp64Libcalls[CmpInst::FCMP_OGT] = {
290       {RTLIB::OGT_F64, CmpInst::BAD_ICMP_PREDICATE}};
291   FCmp64Libcalls[CmpInst::FCMP_OLE] = {
292       {RTLIB::OLE_F64, CmpInst::BAD_ICMP_PREDICATE}};
293   FCmp64Libcalls[CmpInst::FCMP_OLT] = {
294       {RTLIB::OLT_F64, CmpInst::BAD_ICMP_PREDICATE}};
295   FCmp64Libcalls[CmpInst::FCMP_ORD] = {{RTLIB::UO_F64, CmpInst::ICMP_EQ}};
296   FCmp64Libcalls[CmpInst::FCMP_UGE] = {{RTLIB::OLT_F64, CmpInst::ICMP_EQ}};
297   FCmp64Libcalls[CmpInst::FCMP_UGT] = {{RTLIB::OLE_F64, CmpInst::ICMP_EQ}};
298   FCmp64Libcalls[CmpInst::FCMP_ULE] = {{RTLIB::OGT_F64, CmpInst::ICMP_EQ}};
299   FCmp64Libcalls[CmpInst::FCMP_ULT] = {{RTLIB::OGE_F64, CmpInst::ICMP_EQ}};
300   FCmp64Libcalls[CmpInst::FCMP_UNE] = {{RTLIB::UNE_F64, CmpInst::ICMP_EQ}};
301   FCmp64Libcalls[CmpInst::FCMP_UNO] = {
302       {RTLIB::UO_F64, CmpInst::BAD_ICMP_PREDICATE}};
303   FCmp64Libcalls[CmpInst::FCMP_ONE] = {
304       {RTLIB::OGT_F64, CmpInst::BAD_ICMP_PREDICATE},
305       {RTLIB::OLT_F64, CmpInst::BAD_ICMP_PREDICATE}};
306   FCmp64Libcalls[CmpInst::FCMP_UEQ] = {
307       {RTLIB::OEQ_F64, CmpInst::BAD_ICMP_PREDICATE},
308       {RTLIB::UO_F64, CmpInst::BAD_ICMP_PREDICATE}};
309 }
310 
311 void ARMLegalizerInfo::setFCmpLibcallsGNU() {
312   // FCMP_TRUE and FCMP_FALSE don't need libcalls, they should be
313   // default-initialized.
314   FCmp32Libcalls.resize(CmpInst::LAST_FCMP_PREDICATE + 1);
315   FCmp32Libcalls[CmpInst::FCMP_OEQ] = {{RTLIB::OEQ_F32, CmpInst::ICMP_EQ}};
316   FCmp32Libcalls[CmpInst::FCMP_OGE] = {{RTLIB::OGE_F32, CmpInst::ICMP_SGE}};
317   FCmp32Libcalls[CmpInst::FCMP_OGT] = {{RTLIB::OGT_F32, CmpInst::ICMP_SGT}};
318   FCmp32Libcalls[CmpInst::FCMP_OLE] = {{RTLIB::OLE_F32, CmpInst::ICMP_SLE}};
319   FCmp32Libcalls[CmpInst::FCMP_OLT] = {{RTLIB::OLT_F32, CmpInst::ICMP_SLT}};
320   FCmp32Libcalls[CmpInst::FCMP_ORD] = {{RTLIB::UO_F32, CmpInst::ICMP_EQ}};
321   FCmp32Libcalls[CmpInst::FCMP_UGE] = {{RTLIB::OLT_F32, CmpInst::ICMP_SGE}};
322   FCmp32Libcalls[CmpInst::FCMP_UGT] = {{RTLIB::OLE_F32, CmpInst::ICMP_SGT}};
323   FCmp32Libcalls[CmpInst::FCMP_ULE] = {{RTLIB::OGT_F32, CmpInst::ICMP_SLE}};
324   FCmp32Libcalls[CmpInst::FCMP_ULT] = {{RTLIB::OGE_F32, CmpInst::ICMP_SLT}};
325   FCmp32Libcalls[CmpInst::FCMP_UNE] = {{RTLIB::UNE_F32, CmpInst::ICMP_NE}};
326   FCmp32Libcalls[CmpInst::FCMP_UNO] = {{RTLIB::UO_F32, CmpInst::ICMP_NE}};
327   FCmp32Libcalls[CmpInst::FCMP_ONE] = {{RTLIB::OGT_F32, CmpInst::ICMP_SGT},
328                                        {RTLIB::OLT_F32, CmpInst::ICMP_SLT}};
329   FCmp32Libcalls[CmpInst::FCMP_UEQ] = {{RTLIB::OEQ_F32, CmpInst::ICMP_EQ},
330                                        {RTLIB::UO_F32, CmpInst::ICMP_NE}};
331 
332   FCmp64Libcalls.resize(CmpInst::LAST_FCMP_PREDICATE + 1);
333   FCmp64Libcalls[CmpInst::FCMP_OEQ] = {{RTLIB::OEQ_F64, CmpInst::ICMP_EQ}};
334   FCmp64Libcalls[CmpInst::FCMP_OGE] = {{RTLIB::OGE_F64, CmpInst::ICMP_SGE}};
335   FCmp64Libcalls[CmpInst::FCMP_OGT] = {{RTLIB::OGT_F64, CmpInst::ICMP_SGT}};
336   FCmp64Libcalls[CmpInst::FCMP_OLE] = {{RTLIB::OLE_F64, CmpInst::ICMP_SLE}};
337   FCmp64Libcalls[CmpInst::FCMP_OLT] = {{RTLIB::OLT_F64, CmpInst::ICMP_SLT}};
338   FCmp64Libcalls[CmpInst::FCMP_ORD] = {{RTLIB::UO_F64, CmpInst::ICMP_EQ}};
339   FCmp64Libcalls[CmpInst::FCMP_UGE] = {{RTLIB::OLT_F64, CmpInst::ICMP_SGE}};
340   FCmp64Libcalls[CmpInst::FCMP_UGT] = {{RTLIB::OLE_F64, CmpInst::ICMP_SGT}};
341   FCmp64Libcalls[CmpInst::FCMP_ULE] = {{RTLIB::OGT_F64, CmpInst::ICMP_SLE}};
342   FCmp64Libcalls[CmpInst::FCMP_ULT] = {{RTLIB::OGE_F64, CmpInst::ICMP_SLT}};
343   FCmp64Libcalls[CmpInst::FCMP_UNE] = {{RTLIB::UNE_F64, CmpInst::ICMP_NE}};
344   FCmp64Libcalls[CmpInst::FCMP_UNO] = {{RTLIB::UO_F64, CmpInst::ICMP_NE}};
345   FCmp64Libcalls[CmpInst::FCMP_ONE] = {{RTLIB::OGT_F64, CmpInst::ICMP_SGT},
346                                        {RTLIB::OLT_F64, CmpInst::ICMP_SLT}};
347   FCmp64Libcalls[CmpInst::FCMP_UEQ] = {{RTLIB::OEQ_F64, CmpInst::ICMP_EQ},
348                                        {RTLIB::UO_F64, CmpInst::ICMP_NE}};
349 }
350 
351 ARMLegalizerInfo::FCmpLibcallsList
352 ARMLegalizerInfo::getFCmpLibcalls(CmpInst::Predicate Predicate,
353                                   unsigned Size) const {
354   assert(CmpInst::isFPPredicate(Predicate) && "Unsupported FCmp predicate");
355   if (Size == 32)
356     return FCmp32Libcalls[Predicate];
357   if (Size == 64)
358     return FCmp64Libcalls[Predicate];
359   llvm_unreachable("Unsupported size for FCmp predicate");
360 }
361 
362 bool ARMLegalizerInfo::legalizeCustom(LegalizerHelper &Helper,
363                                       MachineInstr &MI) const {
364   using namespace TargetOpcode;
365 
366   MachineIRBuilder &MIRBuilder = Helper.MIRBuilder;
367   MachineRegisterInfo &MRI = *MIRBuilder.getMRI();
368   LLVMContext &Ctx = MIRBuilder.getMF().getFunction().getContext();
369 
370   switch (MI.getOpcode()) {
371   default:
372     return false;
373   case G_SREM:
374   case G_UREM: {
375     Register OriginalResult = MI.getOperand(0).getReg();
376     auto Size = MRI.getType(OriginalResult).getSizeInBits();
377     if (Size != 32)
378       return false;
379 
380     auto Libcall =
381         MI.getOpcode() == G_SREM ? RTLIB::SDIVREM_I32 : RTLIB::UDIVREM_I32;
382 
383     // Our divmod libcalls return a struct containing the quotient and the
384     // remainder. Create a new, unused register for the quotient and use the
385     // destination of the original instruction for the remainder.
386     Type *ArgTy = Type::getInt32Ty(Ctx);
387     StructType *RetTy = StructType::get(Ctx, {ArgTy, ArgTy}, /* Packed */ true);
388     Register RetRegs[] = {MRI.createGenericVirtualRegister(LLT::scalar(32)),
389                           OriginalResult};
390     auto Status = createLibcall(MIRBuilder, Libcall, {RetRegs, RetTy},
391                                 {{MI.getOperand(1).getReg(), ArgTy},
392                                  {MI.getOperand(2).getReg(), ArgTy}});
393     if (Status != LegalizerHelper::Legalized)
394       return false;
395     break;
396   }
397   case G_FCMP: {
398     assert(MRI.getType(MI.getOperand(2).getReg()) ==
399                MRI.getType(MI.getOperand(3).getReg()) &&
400            "Mismatched operands for G_FCMP");
401     auto OpSize = MRI.getType(MI.getOperand(2).getReg()).getSizeInBits();
402 
403     auto OriginalResult = MI.getOperand(0).getReg();
404     auto Predicate =
405         static_cast<CmpInst::Predicate>(MI.getOperand(1).getPredicate());
406     auto Libcalls = getFCmpLibcalls(Predicate, OpSize);
407 
408     if (Libcalls.empty()) {
409       assert((Predicate == CmpInst::FCMP_TRUE ||
410               Predicate == CmpInst::FCMP_FALSE) &&
411              "Predicate needs libcalls, but none specified");
412       MIRBuilder.buildConstant(OriginalResult,
413                                Predicate == CmpInst::FCMP_TRUE ? 1 : 0);
414       MI.eraseFromParent();
415       return true;
416     }
417 
418     assert((OpSize == 32 || OpSize == 64) && "Unsupported operand size");
419     auto *ArgTy = OpSize == 32 ? Type::getFloatTy(Ctx) : Type::getDoubleTy(Ctx);
420     auto *RetTy = Type::getInt32Ty(Ctx);
421 
422     SmallVector<Register, 2> Results;
423     for (auto Libcall : Libcalls) {
424       auto LibcallResult = MRI.createGenericVirtualRegister(LLT::scalar(32));
425       auto Status =
426           createLibcall(MIRBuilder, Libcall.LibcallID, {LibcallResult, RetTy},
427                         {{MI.getOperand(2).getReg(), ArgTy},
428                          {MI.getOperand(3).getReg(), ArgTy}});
429 
430       if (Status != LegalizerHelper::Legalized)
431         return false;
432 
433       auto ProcessedResult =
434           Libcalls.size() == 1
435               ? OriginalResult
436               : MRI.createGenericVirtualRegister(MRI.getType(OriginalResult));
437 
438       // We have a result, but we need to transform it into a proper 1-bit 0 or
439       // 1, taking into account the different peculiarities of the values
440       // returned by the comparison functions.
441       CmpInst::Predicate ResultPred = Libcall.Predicate;
442       if (ResultPred == CmpInst::BAD_ICMP_PREDICATE) {
443         // We have a nice 0 or 1, and we just need to truncate it back to 1 bit
444         // to keep the types consistent.
445         MIRBuilder.buildTrunc(ProcessedResult, LibcallResult);
446       } else {
447         // We need to compare against 0.
448         assert(CmpInst::isIntPredicate(ResultPred) && "Unsupported predicate");
449         auto Zero = MIRBuilder.buildConstant(LLT::scalar(32), 0);
450         MIRBuilder.buildICmp(ResultPred, ProcessedResult, LibcallResult, Zero);
451       }
452       Results.push_back(ProcessedResult);
453     }
454 
455     if (Results.size() != 1) {
456       assert(Results.size() == 2 && "Unexpected number of results");
457       MIRBuilder.buildOr(OriginalResult, Results[0], Results[1]);
458     }
459     break;
460   }
461   case G_FCONSTANT: {
462     // Convert to integer constants, while preserving the binary representation.
463     auto AsInteger =
464         MI.getOperand(1).getFPImm()->getValueAPF().bitcastToAPInt();
465     MIRBuilder.buildConstant(MI.getOperand(0),
466                              *ConstantInt::get(Ctx, AsInteger));
467     break;
468   }
469   }
470 
471   MI.eraseFromParent();
472   return true;
473 }
474