xref: /freebsd/contrib/llvm-project/llvm/lib/Target/ARM/ARMLegalizerInfo.cpp (revision 3e8eb5c7f4909209c042403ddee340b2ee7003a5)
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({{s8, p0, s8, 8},
153                                                           {s16, p0, s16, 8},
154                                                           {s32, p0, s32, 8},
155                                                           {p0, p0, p0, 8}})
156                                .unsupportedIfMemSizeNotPow2();
157 
158   getActionDefinitionsBuilder(G_FRAME_INDEX).legalFor({p0});
159   getActionDefinitionsBuilder(G_GLOBAL_VALUE).legalFor({p0});
160 
161   auto &PhiBuilder =
162       getActionDefinitionsBuilder(G_PHI)
163           .legalFor({s32, p0})
164           .minScalar(0, s32);
165 
166   getActionDefinitionsBuilder(G_PTR_ADD)
167       .legalFor({{p0, s32}})
168       .minScalar(1, s32);
169 
170   getActionDefinitionsBuilder(G_BRCOND).legalFor({s1});
171 
172   if (!ST.useSoftFloat() && ST.hasVFP2Base()) {
173     getActionDefinitionsBuilder(
174         {G_FADD, G_FSUB, G_FMUL, G_FDIV, G_FCONSTANT, G_FNEG})
175         .legalFor({s32, s64});
176 
177     LoadStoreBuilder
178         .legalForTypesWithMemDesc({{s64, p0, s64, 32}})
179         .maxScalar(0, s32);
180     PhiBuilder.legalFor({s64});
181 
182     getActionDefinitionsBuilder(G_FCMP).legalForCartesianProduct({s1},
183                                                                  {s32, s64});
184 
185     getActionDefinitionsBuilder(G_MERGE_VALUES).legalFor({{s64, s32}});
186     getActionDefinitionsBuilder(G_UNMERGE_VALUES).legalFor({{s32, s64}});
187 
188     getActionDefinitionsBuilder(G_FPEXT).legalFor({{s64, s32}});
189     getActionDefinitionsBuilder(G_FPTRUNC).legalFor({{s32, s64}});
190 
191     getActionDefinitionsBuilder({G_FPTOSI, G_FPTOUI})
192         .legalForCartesianProduct({s32}, {s32, s64});
193     getActionDefinitionsBuilder({G_SITOFP, G_UITOFP})
194         .legalForCartesianProduct({s32, s64}, {s32});
195   } else {
196     getActionDefinitionsBuilder({G_FADD, G_FSUB, G_FMUL, G_FDIV})
197         .libcallFor({s32, s64});
198 
199     LoadStoreBuilder.maxScalar(0, s32);
200 
201     for (auto Ty : {s32, s64})
202       LegacyInfo.setAction({G_FNEG, Ty}, LegacyLegalizeActions::Lower);
203 
204     getActionDefinitionsBuilder(G_FCONSTANT).customFor({s32, s64});
205 
206     getActionDefinitionsBuilder(G_FCMP).customForCartesianProduct({s1},
207                                                                   {s32, s64});
208 
209     if (AEABI(ST))
210       setFCmpLibcallsAEABI();
211     else
212       setFCmpLibcallsGNU();
213 
214     getActionDefinitionsBuilder(G_FPEXT).libcallFor({{s64, s32}});
215     getActionDefinitionsBuilder(G_FPTRUNC).libcallFor({{s32, s64}});
216 
217     getActionDefinitionsBuilder({G_FPTOSI, G_FPTOUI})
218         .libcallForCartesianProduct({s32}, {s32, s64});
219     getActionDefinitionsBuilder({G_SITOFP, G_UITOFP})
220         .libcallForCartesianProduct({s32, s64}, {s32});
221   }
222 
223   // Just expand whatever loads and stores are left.
224   LoadStoreBuilder.lower();
225 
226   if (!ST.useSoftFloat() && ST.hasVFP4Base())
227     getActionDefinitionsBuilder(G_FMA).legalFor({s32, s64});
228   else
229     getActionDefinitionsBuilder(G_FMA).libcallFor({s32, s64});
230 
231   getActionDefinitionsBuilder({G_FREM, G_FPOW}).libcallFor({s32, s64});
232 
233   if (ST.hasV5TOps()) {
234     getActionDefinitionsBuilder(G_CTLZ)
235         .legalFor({s32, s32})
236         .clampScalar(1, s32, s32)
237         .clampScalar(0, s32, s32);
238     getActionDefinitionsBuilder(G_CTLZ_ZERO_UNDEF)
239         .lowerFor({s32, s32})
240         .clampScalar(1, s32, s32)
241         .clampScalar(0, s32, s32);
242   } else {
243     getActionDefinitionsBuilder(G_CTLZ_ZERO_UNDEF)
244         .libcallFor({s32, s32})
245         .clampScalar(1, s32, s32)
246         .clampScalar(0, s32, s32);
247     getActionDefinitionsBuilder(G_CTLZ)
248         .lowerFor({s32, s32})
249         .clampScalar(1, s32, s32)
250         .clampScalar(0, s32, s32);
251   }
252 
253   LegacyInfo.computeTables();
254   verify(*ST.getInstrInfo());
255 }
256 
257 void ARMLegalizerInfo::setFCmpLibcallsAEABI() {
258   // FCMP_TRUE and FCMP_FALSE don't need libcalls, they should be
259   // default-initialized.
260   FCmp32Libcalls.resize(CmpInst::LAST_FCMP_PREDICATE + 1);
261   FCmp32Libcalls[CmpInst::FCMP_OEQ] = {
262       {RTLIB::OEQ_F32, CmpInst::BAD_ICMP_PREDICATE}};
263   FCmp32Libcalls[CmpInst::FCMP_OGE] = {
264       {RTLIB::OGE_F32, CmpInst::BAD_ICMP_PREDICATE}};
265   FCmp32Libcalls[CmpInst::FCMP_OGT] = {
266       {RTLIB::OGT_F32, CmpInst::BAD_ICMP_PREDICATE}};
267   FCmp32Libcalls[CmpInst::FCMP_OLE] = {
268       {RTLIB::OLE_F32, CmpInst::BAD_ICMP_PREDICATE}};
269   FCmp32Libcalls[CmpInst::FCMP_OLT] = {
270       {RTLIB::OLT_F32, CmpInst::BAD_ICMP_PREDICATE}};
271   FCmp32Libcalls[CmpInst::FCMP_ORD] = {{RTLIB::UO_F32, CmpInst::ICMP_EQ}};
272   FCmp32Libcalls[CmpInst::FCMP_UGE] = {{RTLIB::OLT_F32, CmpInst::ICMP_EQ}};
273   FCmp32Libcalls[CmpInst::FCMP_UGT] = {{RTLIB::OLE_F32, CmpInst::ICMP_EQ}};
274   FCmp32Libcalls[CmpInst::FCMP_ULE] = {{RTLIB::OGT_F32, CmpInst::ICMP_EQ}};
275   FCmp32Libcalls[CmpInst::FCMP_ULT] = {{RTLIB::OGE_F32, CmpInst::ICMP_EQ}};
276   FCmp32Libcalls[CmpInst::FCMP_UNE] = {{RTLIB::UNE_F32, CmpInst::ICMP_EQ}};
277   FCmp32Libcalls[CmpInst::FCMP_UNO] = {
278       {RTLIB::UO_F32, CmpInst::BAD_ICMP_PREDICATE}};
279   FCmp32Libcalls[CmpInst::FCMP_ONE] = {
280       {RTLIB::OGT_F32, CmpInst::BAD_ICMP_PREDICATE},
281       {RTLIB::OLT_F32, CmpInst::BAD_ICMP_PREDICATE}};
282   FCmp32Libcalls[CmpInst::FCMP_UEQ] = {
283       {RTLIB::OEQ_F32, CmpInst::BAD_ICMP_PREDICATE},
284       {RTLIB::UO_F32, CmpInst::BAD_ICMP_PREDICATE}};
285 
286   FCmp64Libcalls.resize(CmpInst::LAST_FCMP_PREDICATE + 1);
287   FCmp64Libcalls[CmpInst::FCMP_OEQ] = {
288       {RTLIB::OEQ_F64, CmpInst::BAD_ICMP_PREDICATE}};
289   FCmp64Libcalls[CmpInst::FCMP_OGE] = {
290       {RTLIB::OGE_F64, CmpInst::BAD_ICMP_PREDICATE}};
291   FCmp64Libcalls[CmpInst::FCMP_OGT] = {
292       {RTLIB::OGT_F64, CmpInst::BAD_ICMP_PREDICATE}};
293   FCmp64Libcalls[CmpInst::FCMP_OLE] = {
294       {RTLIB::OLE_F64, CmpInst::BAD_ICMP_PREDICATE}};
295   FCmp64Libcalls[CmpInst::FCMP_OLT] = {
296       {RTLIB::OLT_F64, CmpInst::BAD_ICMP_PREDICATE}};
297   FCmp64Libcalls[CmpInst::FCMP_ORD] = {{RTLIB::UO_F64, CmpInst::ICMP_EQ}};
298   FCmp64Libcalls[CmpInst::FCMP_UGE] = {{RTLIB::OLT_F64, CmpInst::ICMP_EQ}};
299   FCmp64Libcalls[CmpInst::FCMP_UGT] = {{RTLIB::OLE_F64, CmpInst::ICMP_EQ}};
300   FCmp64Libcalls[CmpInst::FCMP_ULE] = {{RTLIB::OGT_F64, CmpInst::ICMP_EQ}};
301   FCmp64Libcalls[CmpInst::FCMP_ULT] = {{RTLIB::OGE_F64, CmpInst::ICMP_EQ}};
302   FCmp64Libcalls[CmpInst::FCMP_UNE] = {{RTLIB::UNE_F64, CmpInst::ICMP_EQ}};
303   FCmp64Libcalls[CmpInst::FCMP_UNO] = {
304       {RTLIB::UO_F64, CmpInst::BAD_ICMP_PREDICATE}};
305   FCmp64Libcalls[CmpInst::FCMP_ONE] = {
306       {RTLIB::OGT_F64, CmpInst::BAD_ICMP_PREDICATE},
307       {RTLIB::OLT_F64, CmpInst::BAD_ICMP_PREDICATE}};
308   FCmp64Libcalls[CmpInst::FCMP_UEQ] = {
309       {RTLIB::OEQ_F64, CmpInst::BAD_ICMP_PREDICATE},
310       {RTLIB::UO_F64, CmpInst::BAD_ICMP_PREDICATE}};
311 }
312 
313 void ARMLegalizerInfo::setFCmpLibcallsGNU() {
314   // FCMP_TRUE and FCMP_FALSE don't need libcalls, they should be
315   // default-initialized.
316   FCmp32Libcalls.resize(CmpInst::LAST_FCMP_PREDICATE + 1);
317   FCmp32Libcalls[CmpInst::FCMP_OEQ] = {{RTLIB::OEQ_F32, CmpInst::ICMP_EQ}};
318   FCmp32Libcalls[CmpInst::FCMP_OGE] = {{RTLIB::OGE_F32, CmpInst::ICMP_SGE}};
319   FCmp32Libcalls[CmpInst::FCMP_OGT] = {{RTLIB::OGT_F32, CmpInst::ICMP_SGT}};
320   FCmp32Libcalls[CmpInst::FCMP_OLE] = {{RTLIB::OLE_F32, CmpInst::ICMP_SLE}};
321   FCmp32Libcalls[CmpInst::FCMP_OLT] = {{RTLIB::OLT_F32, CmpInst::ICMP_SLT}};
322   FCmp32Libcalls[CmpInst::FCMP_ORD] = {{RTLIB::UO_F32, CmpInst::ICMP_EQ}};
323   FCmp32Libcalls[CmpInst::FCMP_UGE] = {{RTLIB::OLT_F32, CmpInst::ICMP_SGE}};
324   FCmp32Libcalls[CmpInst::FCMP_UGT] = {{RTLIB::OLE_F32, CmpInst::ICMP_SGT}};
325   FCmp32Libcalls[CmpInst::FCMP_ULE] = {{RTLIB::OGT_F32, CmpInst::ICMP_SLE}};
326   FCmp32Libcalls[CmpInst::FCMP_ULT] = {{RTLIB::OGE_F32, CmpInst::ICMP_SLT}};
327   FCmp32Libcalls[CmpInst::FCMP_UNE] = {{RTLIB::UNE_F32, CmpInst::ICMP_NE}};
328   FCmp32Libcalls[CmpInst::FCMP_UNO] = {{RTLIB::UO_F32, CmpInst::ICMP_NE}};
329   FCmp32Libcalls[CmpInst::FCMP_ONE] = {{RTLIB::OGT_F32, CmpInst::ICMP_SGT},
330                                        {RTLIB::OLT_F32, CmpInst::ICMP_SLT}};
331   FCmp32Libcalls[CmpInst::FCMP_UEQ] = {{RTLIB::OEQ_F32, CmpInst::ICMP_EQ},
332                                        {RTLIB::UO_F32, CmpInst::ICMP_NE}};
333 
334   FCmp64Libcalls.resize(CmpInst::LAST_FCMP_PREDICATE + 1);
335   FCmp64Libcalls[CmpInst::FCMP_OEQ] = {{RTLIB::OEQ_F64, CmpInst::ICMP_EQ}};
336   FCmp64Libcalls[CmpInst::FCMP_OGE] = {{RTLIB::OGE_F64, CmpInst::ICMP_SGE}};
337   FCmp64Libcalls[CmpInst::FCMP_OGT] = {{RTLIB::OGT_F64, CmpInst::ICMP_SGT}};
338   FCmp64Libcalls[CmpInst::FCMP_OLE] = {{RTLIB::OLE_F64, CmpInst::ICMP_SLE}};
339   FCmp64Libcalls[CmpInst::FCMP_OLT] = {{RTLIB::OLT_F64, CmpInst::ICMP_SLT}};
340   FCmp64Libcalls[CmpInst::FCMP_ORD] = {{RTLIB::UO_F64, CmpInst::ICMP_EQ}};
341   FCmp64Libcalls[CmpInst::FCMP_UGE] = {{RTLIB::OLT_F64, CmpInst::ICMP_SGE}};
342   FCmp64Libcalls[CmpInst::FCMP_UGT] = {{RTLIB::OLE_F64, CmpInst::ICMP_SGT}};
343   FCmp64Libcalls[CmpInst::FCMP_ULE] = {{RTLIB::OGT_F64, CmpInst::ICMP_SLE}};
344   FCmp64Libcalls[CmpInst::FCMP_ULT] = {{RTLIB::OGE_F64, CmpInst::ICMP_SLT}};
345   FCmp64Libcalls[CmpInst::FCMP_UNE] = {{RTLIB::UNE_F64, CmpInst::ICMP_NE}};
346   FCmp64Libcalls[CmpInst::FCMP_UNO] = {{RTLIB::UO_F64, CmpInst::ICMP_NE}};
347   FCmp64Libcalls[CmpInst::FCMP_ONE] = {{RTLIB::OGT_F64, CmpInst::ICMP_SGT},
348                                        {RTLIB::OLT_F64, CmpInst::ICMP_SLT}};
349   FCmp64Libcalls[CmpInst::FCMP_UEQ] = {{RTLIB::OEQ_F64, CmpInst::ICMP_EQ},
350                                        {RTLIB::UO_F64, CmpInst::ICMP_NE}};
351 }
352 
353 ARMLegalizerInfo::FCmpLibcallsList
354 ARMLegalizerInfo::getFCmpLibcalls(CmpInst::Predicate Predicate,
355                                   unsigned Size) const {
356   assert(CmpInst::isFPPredicate(Predicate) && "Unsupported FCmp predicate");
357   if (Size == 32)
358     return FCmp32Libcalls[Predicate];
359   if (Size == 64)
360     return FCmp64Libcalls[Predicate];
361   llvm_unreachable("Unsupported size for FCmp predicate");
362 }
363 
364 bool ARMLegalizerInfo::legalizeCustom(LegalizerHelper &Helper,
365                                       MachineInstr &MI) const {
366   using namespace TargetOpcode;
367 
368   MachineIRBuilder &MIRBuilder = Helper.MIRBuilder;
369   MachineRegisterInfo &MRI = *MIRBuilder.getMRI();
370   LLVMContext &Ctx = MIRBuilder.getMF().getFunction().getContext();
371 
372   switch (MI.getOpcode()) {
373   default:
374     return false;
375   case G_SREM:
376   case G_UREM: {
377     Register OriginalResult = MI.getOperand(0).getReg();
378     auto Size = MRI.getType(OriginalResult).getSizeInBits();
379     if (Size != 32)
380       return false;
381 
382     auto Libcall =
383         MI.getOpcode() == G_SREM ? RTLIB::SDIVREM_I32 : RTLIB::UDIVREM_I32;
384 
385     // Our divmod libcalls return a struct containing the quotient and the
386     // remainder. Create a new, unused register for the quotient and use the
387     // destination of the original instruction for the remainder.
388     Type *ArgTy = Type::getInt32Ty(Ctx);
389     StructType *RetTy = StructType::get(Ctx, {ArgTy, ArgTy}, /* Packed */ true);
390     Register RetRegs[] = {MRI.createGenericVirtualRegister(LLT::scalar(32)),
391                           OriginalResult};
392     auto Status = createLibcall(MIRBuilder, Libcall, {RetRegs, RetTy, 0},
393                                 {{MI.getOperand(1).getReg(), ArgTy, 0},
394                                  {MI.getOperand(2).getReg(), ArgTy, 0}});
395     if (Status != LegalizerHelper::Legalized)
396       return false;
397     break;
398   }
399   case G_FCMP: {
400     assert(MRI.getType(MI.getOperand(2).getReg()) ==
401                MRI.getType(MI.getOperand(3).getReg()) &&
402            "Mismatched operands for G_FCMP");
403     auto OpSize = MRI.getType(MI.getOperand(2).getReg()).getSizeInBits();
404 
405     auto OriginalResult = MI.getOperand(0).getReg();
406     auto Predicate =
407         static_cast<CmpInst::Predicate>(MI.getOperand(1).getPredicate());
408     auto Libcalls = getFCmpLibcalls(Predicate, OpSize);
409 
410     if (Libcalls.empty()) {
411       assert((Predicate == CmpInst::FCMP_TRUE ||
412               Predicate == CmpInst::FCMP_FALSE) &&
413              "Predicate needs libcalls, but none specified");
414       MIRBuilder.buildConstant(OriginalResult,
415                                Predicate == CmpInst::FCMP_TRUE ? 1 : 0);
416       MI.eraseFromParent();
417       return true;
418     }
419 
420     assert((OpSize == 32 || OpSize == 64) && "Unsupported operand size");
421     auto *ArgTy = OpSize == 32 ? Type::getFloatTy(Ctx) : Type::getDoubleTy(Ctx);
422     auto *RetTy = Type::getInt32Ty(Ctx);
423 
424     SmallVector<Register, 2> Results;
425     for (auto Libcall : Libcalls) {
426       auto LibcallResult = MRI.createGenericVirtualRegister(LLT::scalar(32));
427       auto Status = createLibcall(MIRBuilder, Libcall.LibcallID,
428                                   {LibcallResult, RetTy, 0},
429                                   {{MI.getOperand(2).getReg(), ArgTy, 0},
430                                    {MI.getOperand(3).getReg(), ArgTy, 0}});
431 
432       if (Status != LegalizerHelper::Legalized)
433         return false;
434 
435       auto ProcessedResult =
436           Libcalls.size() == 1
437               ? OriginalResult
438               : MRI.createGenericVirtualRegister(MRI.getType(OriginalResult));
439 
440       // We have a result, but we need to transform it into a proper 1-bit 0 or
441       // 1, taking into account the different peculiarities of the values
442       // returned by the comparison functions.
443       CmpInst::Predicate ResultPred = Libcall.Predicate;
444       if (ResultPred == CmpInst::BAD_ICMP_PREDICATE) {
445         // We have a nice 0 or 1, and we just need to truncate it back to 1 bit
446         // to keep the types consistent.
447         MIRBuilder.buildTrunc(ProcessedResult, LibcallResult);
448       } else {
449         // We need to compare against 0.
450         assert(CmpInst::isIntPredicate(ResultPred) && "Unsupported predicate");
451         auto Zero = MIRBuilder.buildConstant(LLT::scalar(32), 0);
452         MIRBuilder.buildICmp(ResultPred, ProcessedResult, LibcallResult, Zero);
453       }
454       Results.push_back(ProcessedResult);
455     }
456 
457     if (Results.size() != 1) {
458       assert(Results.size() == 2 && "Unexpected number of results");
459       MIRBuilder.buildOr(OriginalResult, Results[0], Results[1]);
460     }
461     break;
462   }
463   case G_FCONSTANT: {
464     // Convert to integer constants, while preserving the binary representation.
465     auto AsInteger =
466         MI.getOperand(1).getFPImm()->getValueAPF().bitcastToAPInt();
467     MIRBuilder.buildConstant(MI.getOperand(0),
468                              *ConstantInt::get(Ctx, AsInteger));
469     break;
470   }
471   }
472 
473   MI.eraseFromParent();
474   return true;
475 }
476