xref: /freebsd/contrib/llvm-project/llvm/lib/Target/Mips/MipsCallLowering.cpp (revision a7dea1671b87c07d2d266f836bfa8b58efc7c134) 
1 //===- MipsCallLowering.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 //
9 /// \file
10 /// This file implements the lowering of LLVM calls to machine code calls for
11 /// GlobalISel.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "MipsCallLowering.h"
16 #include "MipsCCState.h"
17 #include "MipsMachineFunction.h"
18 #include "MipsTargetMachine.h"
19 #include "llvm/CodeGen/Analysis.h"
20 #include "llvm/CodeGen/GlobalISel/MachineIRBuilder.h"
21 
22 using namespace llvm;
23 
24 MipsCallLowering::MipsCallLowering(const MipsTargetLowering &TLI)
25     : CallLowering(&TLI) {}
26 
27 bool MipsCallLowering::MipsHandler::assign(Register VReg, const CCValAssign &VA,
28                                            const EVT &VT) {
29   if (VA.isRegLoc()) {
30     assignValueToReg(VReg, VA, VT);
31   } else if (VA.isMemLoc()) {
32     assignValueToAddress(VReg, VA);
33   } else {
34     return false;
35   }
36   return true;
37 }
38 
39 bool MipsCallLowering::MipsHandler::assignVRegs(ArrayRef<Register> VRegs,
40                                                 ArrayRef<CCValAssign> ArgLocs,
41                                                 unsigned ArgLocsStartIndex,
42                                                 const EVT &VT) {
43   for (unsigned i = 0; i < VRegs.size(); ++i)
44     if (!assign(VRegs[i], ArgLocs[ArgLocsStartIndex + i], VT))
45       return false;
46   return true;
47 }
48 
49 void MipsCallLowering::MipsHandler::setLeastSignificantFirst(
50     SmallVectorImpl<Register> &VRegs) {
51   if (!MIRBuilder.getMF().getDataLayout().isLittleEndian())
52     std::reverse(VRegs.begin(), VRegs.end());
53 }
54 
55 bool MipsCallLowering::MipsHandler::handle(
56     ArrayRef<CCValAssign> ArgLocs, ArrayRef<CallLowering::ArgInfo> Args) {
57   SmallVector<Register, 4> VRegs;
58   unsigned SplitLength;
59   const Function &F = MIRBuilder.getMF().getFunction();
60   const DataLayout &DL = F.getParent()->getDataLayout();
61   const MipsTargetLowering &TLI = *static_cast<const MipsTargetLowering *>(
62       MIRBuilder.getMF().getSubtarget().getTargetLowering());
63 
64   for (unsigned ArgsIndex = 0, ArgLocsIndex = 0; ArgsIndex < Args.size();
65        ++ArgsIndex, ArgLocsIndex += SplitLength) {
66     EVT VT = TLI.getValueType(DL, Args[ArgsIndex].Ty);
67     SplitLength = TLI.getNumRegistersForCallingConv(F.getContext(),
68                                                     F.getCallingConv(), VT);
69     assert(Args[ArgsIndex].Regs.size() == 1 && "Can't handle multple regs yet");
70 
71     if (SplitLength > 1) {
72       VRegs.clear();
73       MVT RegisterVT = TLI.getRegisterTypeForCallingConv(
74           F.getContext(), F.getCallingConv(), VT);
75       for (unsigned i = 0; i < SplitLength; ++i)
76         VRegs.push_back(MRI.createGenericVirtualRegister(LLT{RegisterVT}));
77 
78       if (!handleSplit(VRegs, ArgLocs, ArgLocsIndex, Args[ArgsIndex].Regs[0],
79                        VT))
80         return false;
81     } else {
82       if (!assign(Args[ArgsIndex].Regs[0], ArgLocs[ArgLocsIndex], VT))
83         return false;
84     }
85   }
86   return true;
87 }
88 
89 namespace {
90 class IncomingValueHandler : public MipsCallLowering::MipsHandler {
91 public:
92   IncomingValueHandler(MachineIRBuilder &MIRBuilder, MachineRegisterInfo &MRI)
93       : MipsHandler(MIRBuilder, MRI) {}
94 
95 private:
96   void assignValueToReg(Register ValVReg, const CCValAssign &VA,
97                         const EVT &VT) override;
98 
99   Register getStackAddress(const CCValAssign &VA,
100                            MachineMemOperand *&MMO) override;
101 
102   void assignValueToAddress(Register ValVReg, const CCValAssign &VA) override;
103 
104   bool handleSplit(SmallVectorImpl<Register> &VRegs,
105                    ArrayRef<CCValAssign> ArgLocs, unsigned ArgLocsStartIndex,
106                    Register ArgsReg, const EVT &VT) override;
107 
108   virtual void markPhysRegUsed(unsigned PhysReg) {
109     MIRBuilder.getMRI()->addLiveIn(PhysReg);
110     MIRBuilder.getMBB().addLiveIn(PhysReg);
111   }
112 
113   void buildLoad(Register Val, const CCValAssign &VA) {
114     MachineMemOperand *MMO;
115     Register Addr = getStackAddress(VA, MMO);
116     MIRBuilder.buildLoad(Val, Addr, *MMO);
117   }
118 };
119 
120 class CallReturnHandler : public IncomingValueHandler {
121 public:
122   CallReturnHandler(MachineIRBuilder &MIRBuilder, MachineRegisterInfo &MRI,
123                     MachineInstrBuilder &MIB)
124       : IncomingValueHandler(MIRBuilder, MRI), MIB(MIB) {}
125 
126 private:
127   void markPhysRegUsed(unsigned PhysReg) override {
128     MIB.addDef(PhysReg, RegState::Implicit);
129   }
130 
131   MachineInstrBuilder &MIB;
132 };
133 
134 } // end anonymous namespace
135 
136 void IncomingValueHandler::assignValueToReg(Register ValVReg,
137                                             const CCValAssign &VA,
138                                             const EVT &VT) {
139   const MipsSubtarget &STI =
140       static_cast<const MipsSubtarget &>(MIRBuilder.getMF().getSubtarget());
141   Register PhysReg = VA.getLocReg();
142   if (VT == MVT::f64 && PhysReg >= Mips::A0 && PhysReg <= Mips::A3) {
143     const MipsSubtarget &STI =
144         static_cast<const MipsSubtarget &>(MIRBuilder.getMF().getSubtarget());
145 
146     MIRBuilder
147         .buildInstr(STI.isFP64bit() ? Mips::BuildPairF64_64
148                                     : Mips::BuildPairF64)
149         .addDef(ValVReg)
150         .addUse(PhysReg + (STI.isLittle() ? 0 : 1))
151         .addUse(PhysReg + (STI.isLittle() ? 1 : 0))
152         .constrainAllUses(MIRBuilder.getTII(), *STI.getRegisterInfo(),
153                           *STI.getRegBankInfo());
154     markPhysRegUsed(PhysReg);
155     markPhysRegUsed(PhysReg + 1);
156   } else if (VT == MVT::f32 && PhysReg >= Mips::A0 && PhysReg <= Mips::A3) {
157     MIRBuilder.buildInstr(Mips::MTC1)
158         .addDef(ValVReg)
159         .addUse(PhysReg)
160         .constrainAllUses(MIRBuilder.getTII(), *STI.getRegisterInfo(),
161                           *STI.getRegBankInfo());
162     markPhysRegUsed(PhysReg);
163   } else {
164     switch (VA.getLocInfo()) {
165     case CCValAssign::LocInfo::SExt:
166     case CCValAssign::LocInfo::ZExt:
167     case CCValAssign::LocInfo::AExt: {
168       auto Copy = MIRBuilder.buildCopy(LLT{VA.getLocVT()}, PhysReg);
169       MIRBuilder.buildTrunc(ValVReg, Copy);
170       break;
171     }
172     default:
173       MIRBuilder.buildCopy(ValVReg, PhysReg);
174       break;
175     }
176     markPhysRegUsed(PhysReg);
177   }
178 }
179 
180 Register IncomingValueHandler::getStackAddress(const CCValAssign &VA,
181                                                MachineMemOperand *&MMO) {
182   MachineFunction &MF = MIRBuilder.getMF();
183   unsigned Size = alignTo(VA.getValVT().getSizeInBits(), 8) / 8;
184   unsigned Offset = VA.getLocMemOffset();
185   MachineFrameInfo &MFI = MF.getFrameInfo();
186 
187   int FI = MFI.CreateFixedObject(Size, Offset, true);
188   MachinePointerInfo MPO =
189       MachinePointerInfo::getFixedStack(MIRBuilder.getMF(), FI);
190 
191   const TargetFrameLowering *TFL = MF.getSubtarget().getFrameLowering();
192   unsigned Align = MinAlign(TFL->getStackAlignment(), Offset);
193   MMO = MF.getMachineMemOperand(MPO, MachineMemOperand::MOLoad, Size, Align);
194 
195   Register AddrReg = MRI.createGenericVirtualRegister(LLT::pointer(0, 32));
196   MIRBuilder.buildFrameIndex(AddrReg, FI);
197 
198   return AddrReg;
199 }
200 
201 void IncomingValueHandler::assignValueToAddress(Register ValVReg,
202                                                 const CCValAssign &VA) {
203   if (VA.getLocInfo() == CCValAssign::SExt ||
204       VA.getLocInfo() == CCValAssign::ZExt ||
205       VA.getLocInfo() == CCValAssign::AExt) {
206     Register LoadReg = MRI.createGenericVirtualRegister(LLT::scalar(32));
207     buildLoad(LoadReg, VA);
208     MIRBuilder.buildTrunc(ValVReg, LoadReg);
209   } else
210     buildLoad(ValVReg, VA);
211 }
212 
213 bool IncomingValueHandler::handleSplit(SmallVectorImpl<Register> &VRegs,
214                                        ArrayRef<CCValAssign> ArgLocs,
215                                        unsigned ArgLocsStartIndex,
216                                        Register ArgsReg, const EVT &VT) {
217   if (!assignVRegs(VRegs, ArgLocs, ArgLocsStartIndex, VT))
218     return false;
219   setLeastSignificantFirst(VRegs);
220   MIRBuilder.buildMerge(ArgsReg, VRegs);
221   return true;
222 }
223 
224 namespace {
225 class OutgoingValueHandler : public MipsCallLowering::MipsHandler {
226 public:
227   OutgoingValueHandler(MachineIRBuilder &MIRBuilder, MachineRegisterInfo &MRI,
228                        MachineInstrBuilder &MIB)
229       : MipsHandler(MIRBuilder, MRI), MIB(MIB) {}
230 
231 private:
232   void assignValueToReg(Register ValVReg, const CCValAssign &VA,
233                         const EVT &VT) override;
234 
235   Register getStackAddress(const CCValAssign &VA,
236                            MachineMemOperand *&MMO) override;
237 
238   void assignValueToAddress(Register ValVReg, const CCValAssign &VA) override;
239 
240   bool handleSplit(SmallVectorImpl<Register> &VRegs,
241                    ArrayRef<CCValAssign> ArgLocs, unsigned ArgLocsStartIndex,
242                    Register ArgsReg, const EVT &VT) override;
243 
244   Register extendRegister(Register ValReg, const CCValAssign &VA);
245 
246   MachineInstrBuilder &MIB;
247 };
248 } // end anonymous namespace
249 
250 void OutgoingValueHandler::assignValueToReg(Register ValVReg,
251                                             const CCValAssign &VA,
252                                             const EVT &VT) {
253   Register PhysReg = VA.getLocReg();
254   const MipsSubtarget &STI =
255       static_cast<const MipsSubtarget &>(MIRBuilder.getMF().getSubtarget());
256 
257   if (VT == MVT::f64 && PhysReg >= Mips::A0 && PhysReg <= Mips::A3) {
258     MIRBuilder
259         .buildInstr(STI.isFP64bit() ? Mips::ExtractElementF64_64
260                                     : Mips::ExtractElementF64)
261         .addDef(PhysReg + (STI.isLittle() ? 1 : 0))
262         .addUse(ValVReg)
263         .addImm(1)
264         .constrainAllUses(MIRBuilder.getTII(), *STI.getRegisterInfo(),
265                           *STI.getRegBankInfo());
266     MIRBuilder
267         .buildInstr(STI.isFP64bit() ? Mips::ExtractElementF64_64
268                                     : Mips::ExtractElementF64)
269         .addDef(PhysReg + (STI.isLittle() ? 0 : 1))
270         .addUse(ValVReg)
271         .addImm(0)
272         .constrainAllUses(MIRBuilder.getTII(), *STI.getRegisterInfo(),
273                           *STI.getRegBankInfo());
274   } else if (VT == MVT::f32 && PhysReg >= Mips::A0 && PhysReg <= Mips::A3) {
275     MIRBuilder.buildInstr(Mips::MFC1)
276         .addDef(PhysReg)
277         .addUse(ValVReg)
278         .constrainAllUses(MIRBuilder.getTII(), *STI.getRegisterInfo(),
279                           *STI.getRegBankInfo());
280   } else {
281     Register ExtReg = extendRegister(ValVReg, VA);
282     MIRBuilder.buildCopy(PhysReg, ExtReg);
283     MIB.addUse(PhysReg, RegState::Implicit);
284   }
285 }
286 
287 Register OutgoingValueHandler::getStackAddress(const CCValAssign &VA,
288                                                MachineMemOperand *&MMO) {
289   MachineFunction &MF = MIRBuilder.getMF();
290   const TargetFrameLowering *TFL = MF.getSubtarget().getFrameLowering();
291 
292   LLT p0 = LLT::pointer(0, 32);
293   LLT s32 = LLT::scalar(32);
294   Register SPReg = MRI.createGenericVirtualRegister(p0);
295   MIRBuilder.buildCopy(SPReg, Register(Mips::SP));
296 
297   Register OffsetReg = MRI.createGenericVirtualRegister(s32);
298   unsigned Offset = VA.getLocMemOffset();
299   MIRBuilder.buildConstant(OffsetReg, Offset);
300 
301   Register AddrReg = MRI.createGenericVirtualRegister(p0);
302   MIRBuilder.buildGEP(AddrReg, SPReg, OffsetReg);
303 
304   MachinePointerInfo MPO =
305       MachinePointerInfo::getStack(MIRBuilder.getMF(), Offset);
306   unsigned Size = alignTo(VA.getValVT().getSizeInBits(), 8) / 8;
307   unsigned Align = MinAlign(TFL->getStackAlignment(), Offset);
308   MMO = MF.getMachineMemOperand(MPO, MachineMemOperand::MOStore, Size, Align);
309 
310   return AddrReg;
311 }
312 
313 void OutgoingValueHandler::assignValueToAddress(Register ValVReg,
314                                                 const CCValAssign &VA) {
315   MachineMemOperand *MMO;
316   Register Addr = getStackAddress(VA, MMO);
317   Register ExtReg = extendRegister(ValVReg, VA);
318   MIRBuilder.buildStore(ExtReg, Addr, *MMO);
319 }
320 
321 Register OutgoingValueHandler::extendRegister(Register ValReg,
322                                               const CCValAssign &VA) {
323   LLT LocTy{VA.getLocVT()};
324   switch (VA.getLocInfo()) {
325   case CCValAssign::SExt: {
326     Register ExtReg = MRI.createGenericVirtualRegister(LocTy);
327     MIRBuilder.buildSExt(ExtReg, ValReg);
328     return ExtReg;
329   }
330   case CCValAssign::ZExt: {
331     Register ExtReg = MRI.createGenericVirtualRegister(LocTy);
332     MIRBuilder.buildZExt(ExtReg, ValReg);
333     return ExtReg;
334   }
335   case CCValAssign::AExt: {
336     Register ExtReg = MRI.createGenericVirtualRegister(LocTy);
337     MIRBuilder.buildAnyExt(ExtReg, ValReg);
338     return ExtReg;
339   }
340   // TODO : handle upper extends
341   case CCValAssign::Full:
342     return ValReg;
343   default:
344     break;
345   }
346   llvm_unreachable("unable to extend register");
347 }
348 
349 bool OutgoingValueHandler::handleSplit(SmallVectorImpl<Register> &VRegs,
350                                        ArrayRef<CCValAssign> ArgLocs,
351                                        unsigned ArgLocsStartIndex,
352                                        Register ArgsReg, const EVT &VT) {
353   MIRBuilder.buildUnmerge(VRegs, ArgsReg);
354   setLeastSignificantFirst(VRegs);
355   if (!assignVRegs(VRegs, ArgLocs, ArgLocsStartIndex, VT))
356     return false;
357 
358   return true;
359 }
360 
361 static bool isSupportedArgumentType(Type *T) {
362   if (T->isIntegerTy())
363     return true;
364   if (T->isPointerTy())
365     return true;
366   if (T->isFloatingPointTy())
367     return true;
368   return false;
369 }
370 
371 static bool isSupportedReturnType(Type *T) {
372   if (T->isIntegerTy())
373     return true;
374   if (T->isPointerTy())
375     return true;
376   if (T->isFloatingPointTy())
377     return true;
378   if (T->isAggregateType())
379     return true;
380   return false;
381 }
382 
383 static CCValAssign::LocInfo determineLocInfo(const MVT RegisterVT, const EVT VT,
384                                              const ISD::ArgFlagsTy &Flags) {
385   // > does not mean loss of information as type RegisterVT can't hold type VT,
386   // it means that type VT is split into multiple registers of type RegisterVT
387   if (VT.getSizeInBits() >= RegisterVT.getSizeInBits())
388     return CCValAssign::LocInfo::Full;
389   if (Flags.isSExt())
390     return CCValAssign::LocInfo::SExt;
391   if (Flags.isZExt())
392     return CCValAssign::LocInfo::ZExt;
393   return CCValAssign::LocInfo::AExt;
394 }
395 
396 template <typename T>
397 static void setLocInfo(SmallVectorImpl<CCValAssign> &ArgLocs,
398                        const SmallVectorImpl<T> &Arguments) {
399   for (unsigned i = 0; i < ArgLocs.size(); ++i) {
400     const CCValAssign &VA = ArgLocs[i];
401     CCValAssign::LocInfo LocInfo = determineLocInfo(
402         Arguments[i].VT, Arguments[i].ArgVT, Arguments[i].Flags);
403     if (VA.isMemLoc())
404       ArgLocs[i] =
405           CCValAssign::getMem(VA.getValNo(), VA.getValVT(),
406                               VA.getLocMemOffset(), VA.getLocVT(), LocInfo);
407     else
408       ArgLocs[i] = CCValAssign::getReg(VA.getValNo(), VA.getValVT(),
409                                        VA.getLocReg(), VA.getLocVT(), LocInfo);
410   }
411 }
412 
413 bool MipsCallLowering::lowerReturn(MachineIRBuilder &MIRBuilder,
414                                    const Value *Val,
415                                    ArrayRef<Register> VRegs) const {
416 
417   MachineInstrBuilder Ret = MIRBuilder.buildInstrNoInsert(Mips::RetRA);
418 
419   if (Val != nullptr && !isSupportedReturnType(Val->getType()))
420     return false;
421 
422   if (!VRegs.empty()) {
423     MachineFunction &MF = MIRBuilder.getMF();
424     const Function &F = MF.getFunction();
425     const DataLayout &DL = MF.getDataLayout();
426     const MipsTargetLowering &TLI = *getTLI<MipsTargetLowering>();
427 
428     SmallVector<ArgInfo, 8> RetInfos;
429     SmallVector<unsigned, 8> OrigArgIndices;
430 
431     ArgInfo ArgRetInfo(VRegs, Val->getType());
432     setArgFlags(ArgRetInfo, AttributeList::ReturnIndex, DL, F);
433     splitToValueTypes(DL, ArgRetInfo, 0, RetInfos, OrigArgIndices);
434 
435     SmallVector<ISD::OutputArg, 8> Outs;
436     subTargetRegTypeForCallingConv(F, RetInfos, OrigArgIndices, Outs);
437 
438     SmallVector<CCValAssign, 16> ArgLocs;
439     MipsCCState CCInfo(F.getCallingConv(), F.isVarArg(), MF, ArgLocs,
440                        F.getContext());
441     CCInfo.AnalyzeReturn(Outs, TLI.CCAssignFnForReturn());
442     setLocInfo(ArgLocs, Outs);
443 
444     OutgoingValueHandler RetHandler(MIRBuilder, MF.getRegInfo(), Ret);
445     if (!RetHandler.handle(ArgLocs, RetInfos)) {
446       return false;
447     }
448   }
449   MIRBuilder.insertInstr(Ret);
450   return true;
451 }
452 
453 bool MipsCallLowering::lowerFormalArguments(
454     MachineIRBuilder &MIRBuilder, const Function &F,
455     ArrayRef<ArrayRef<Register>> VRegs) const {
456 
457   // Quick exit if there aren't any args.
458   if (F.arg_empty())
459     return true;
460 
461   for (auto &Arg : F.args()) {
462     if (!isSupportedArgumentType(Arg.getType()))
463       return false;
464   }
465 
466   MachineFunction &MF = MIRBuilder.getMF();
467   const DataLayout &DL = MF.getDataLayout();
468   const MipsTargetLowering &TLI = *getTLI<MipsTargetLowering>();
469 
470   SmallVector<ArgInfo, 8> ArgInfos;
471   SmallVector<unsigned, 8> OrigArgIndices;
472   unsigned i = 0;
473   for (auto &Arg : F.args()) {
474     ArgInfo AInfo(VRegs[i], Arg.getType());
475     setArgFlags(AInfo, i + AttributeList::FirstArgIndex, DL, F);
476     ArgInfos.push_back(AInfo);
477     OrigArgIndices.push_back(i);
478     ++i;
479   }
480 
481   SmallVector<ISD::InputArg, 8> Ins;
482   subTargetRegTypeForCallingConv(F, ArgInfos, OrigArgIndices, Ins);
483 
484   SmallVector<CCValAssign, 16> ArgLocs;
485   MipsCCState CCInfo(F.getCallingConv(), F.isVarArg(), MF, ArgLocs,
486                      F.getContext());
487 
488   const MipsTargetMachine &TM =
489       static_cast<const MipsTargetMachine &>(MF.getTarget());
490   const MipsABIInfo &ABI = TM.getABI();
491   CCInfo.AllocateStack(ABI.GetCalleeAllocdArgSizeInBytes(F.getCallingConv()),
492                        1);
493   CCInfo.AnalyzeFormalArguments(Ins, TLI.CCAssignFnForCall());
494   setLocInfo(ArgLocs, Ins);
495 
496   IncomingValueHandler Handler(MIRBuilder, MF.getRegInfo());
497   if (!Handler.handle(ArgLocs, ArgInfos))
498     return false;
499 
500   if (F.isVarArg()) {
501     ArrayRef<MCPhysReg> ArgRegs = ABI.GetVarArgRegs();
502     unsigned Idx = CCInfo.getFirstUnallocated(ArgRegs);
503 
504     int VaArgOffset;
505     unsigned RegSize = 4;
506     if (ArgRegs.size() == Idx)
507       VaArgOffset = alignTo(CCInfo.getNextStackOffset(), RegSize);
508     else {
509       VaArgOffset =
510           (int)ABI.GetCalleeAllocdArgSizeInBytes(CCInfo.getCallingConv()) -
511           (int)(RegSize * (ArgRegs.size() - Idx));
512     }
513 
514     MachineFrameInfo &MFI = MF.getFrameInfo();
515     int FI = MFI.CreateFixedObject(RegSize, VaArgOffset, true);
516     MF.getInfo<MipsFunctionInfo>()->setVarArgsFrameIndex(FI);
517 
518     for (unsigned I = Idx; I < ArgRegs.size(); ++I, VaArgOffset += RegSize) {
519       MIRBuilder.getMBB().addLiveIn(ArgRegs[I]);
520 
521       MachineInstrBuilder Copy =
522           MIRBuilder.buildCopy(LLT::scalar(RegSize * 8), Register(ArgRegs[I]));
523       FI = MFI.CreateFixedObject(RegSize, VaArgOffset, true);
524       MachinePointerInfo MPO = MachinePointerInfo::getFixedStack(MF, FI);
525       MachineInstrBuilder FrameIndex =
526           MIRBuilder.buildFrameIndex(LLT::pointer(MPO.getAddrSpace(), 32), FI);
527       MachineMemOperand *MMO =
528           MF.getMachineMemOperand(MPO, MachineMemOperand::MOStore, RegSize,
529                                   /* Alignment */ RegSize);
530       MIRBuilder.buildStore(Copy, FrameIndex, *MMO);
531     }
532   }
533 
534   return true;
535 }
536 
537 bool MipsCallLowering::lowerCall(MachineIRBuilder &MIRBuilder,
538                                  CallLoweringInfo &Info) const {
539 
540   if (Info.CallConv != CallingConv::C)
541     return false;
542 
543   for (auto &Arg : Info.OrigArgs) {
544     if (!isSupportedArgumentType(Arg.Ty))
545       return false;
546     if (Arg.Flags[0].isByVal())
547       return false;
548     if (Arg.Flags[0].isSRet() && !Arg.Ty->isPointerTy())
549       return false;
550   }
551 
552   if (!Info.OrigRet.Ty->isVoidTy() && !isSupportedReturnType(Info.OrigRet.Ty))
553     return false;
554 
555   MachineFunction &MF = MIRBuilder.getMF();
556   const Function &F = MF.getFunction();
557   const DataLayout &DL = MF.getDataLayout();
558   const MipsTargetLowering &TLI = *getTLI<MipsTargetLowering>();
559   const MipsTargetMachine &TM =
560       static_cast<const MipsTargetMachine &>(MF.getTarget());
561   const MipsABIInfo &ABI = TM.getABI();
562 
563   MachineInstrBuilder CallSeqStart =
564       MIRBuilder.buildInstr(Mips::ADJCALLSTACKDOWN);
565 
566   const bool IsCalleeGlobalPIC =
567       Info.Callee.isGlobal() && TM.isPositionIndependent();
568 
569   MachineInstrBuilder MIB = MIRBuilder.buildInstrNoInsert(
570       Info.Callee.isReg() || IsCalleeGlobalPIC ? Mips::JALRPseudo : Mips::JAL);
571   MIB.addDef(Mips::SP, RegState::Implicit);
572   if (IsCalleeGlobalPIC) {
573     Register CalleeReg =
574         MF.getRegInfo().createGenericVirtualRegister(LLT::pointer(0, 32));
575     MachineInstr *CalleeGlobalValue =
576         MIRBuilder.buildGlobalValue(CalleeReg, Info.Callee.getGlobal());
577     if (!Info.Callee.getGlobal()->hasLocalLinkage())
578       CalleeGlobalValue->getOperand(1).setTargetFlags(MipsII::MO_GOT_CALL);
579     MIB.addUse(CalleeReg);
580   } else
581     MIB.add(Info.Callee);
582   const TargetRegisterInfo *TRI = MF.getSubtarget().getRegisterInfo();
583   MIB.addRegMask(TRI->getCallPreservedMask(MF, F.getCallingConv()));
584 
585   TargetLowering::ArgListTy FuncOrigArgs;
586   FuncOrigArgs.reserve(Info.OrigArgs.size());
587 
588   SmallVector<ArgInfo, 8> ArgInfos;
589   SmallVector<unsigned, 8> OrigArgIndices;
590   unsigned i = 0;
591   for (auto &Arg : Info.OrigArgs) {
592 
593     TargetLowering::ArgListEntry Entry;
594     Entry.Ty = Arg.Ty;
595     FuncOrigArgs.push_back(Entry);
596 
597     ArgInfos.push_back(Arg);
598     OrigArgIndices.push_back(i);
599     ++i;
600   }
601 
602   SmallVector<ISD::OutputArg, 8> Outs;
603   subTargetRegTypeForCallingConv(F, ArgInfos, OrigArgIndices, Outs);
604 
605   SmallVector<CCValAssign, 8> ArgLocs;
606   bool IsCalleeVarArg = false;
607   if (Info.Callee.isGlobal()) {
608     const Function *CF = static_cast<const Function *>(Info.Callee.getGlobal());
609     IsCalleeVarArg = CF->isVarArg();
610   }
611   MipsCCState CCInfo(F.getCallingConv(), IsCalleeVarArg, MF, ArgLocs,
612                      F.getContext());
613 
614   CCInfo.AllocateStack(ABI.GetCalleeAllocdArgSizeInBytes(Info.CallConv), 1);
615   const char *Call =
616       Info.Callee.isSymbol() ? Info.Callee.getSymbolName() : nullptr;
617   CCInfo.AnalyzeCallOperands(Outs, TLI.CCAssignFnForCall(), FuncOrigArgs, Call);
618   setLocInfo(ArgLocs, Outs);
619 
620   OutgoingValueHandler RetHandler(MIRBuilder, MF.getRegInfo(), MIB);
621   if (!RetHandler.handle(ArgLocs, ArgInfos)) {
622     return false;
623   }
624 
625   unsigned NextStackOffset = CCInfo.getNextStackOffset();
626   const TargetFrameLowering *TFL = MF.getSubtarget().getFrameLowering();
627   unsigned StackAlignment = TFL->getStackAlignment();
628   NextStackOffset = alignTo(NextStackOffset, StackAlignment);
629   CallSeqStart.addImm(NextStackOffset).addImm(0);
630 
631   if (IsCalleeGlobalPIC) {
632     MIRBuilder.buildCopy(
633       Register(Mips::GP),
634       MF.getInfo<MipsFunctionInfo>()->getGlobalBaseRegForGlobalISel());
635     MIB.addDef(Mips::GP, RegState::Implicit);
636   }
637   MIRBuilder.insertInstr(MIB);
638   if (MIB->getOpcode() == Mips::JALRPseudo) {
639     const MipsSubtarget &STI =
640         static_cast<const MipsSubtarget &>(MIRBuilder.getMF().getSubtarget());
641     MIB.constrainAllUses(MIRBuilder.getTII(), *STI.getRegisterInfo(),
642                          *STI.getRegBankInfo());
643   }
644 
645   if (!Info.OrigRet.Ty->isVoidTy()) {
646     ArgInfos.clear();
647     SmallVector<unsigned, 8> OrigRetIndices;
648 
649     splitToValueTypes(DL, Info.OrigRet, 0, ArgInfos, OrigRetIndices);
650 
651     SmallVector<ISD::InputArg, 8> Ins;
652     subTargetRegTypeForCallingConv(F, ArgInfos, OrigRetIndices, Ins);
653 
654     SmallVector<CCValAssign, 8> ArgLocs;
655     MipsCCState CCInfo(F.getCallingConv(), F.isVarArg(), MF, ArgLocs,
656                        F.getContext());
657 
658     CCInfo.AnalyzeCallResult(Ins, TLI.CCAssignFnForReturn(), Info.OrigRet.Ty, Call);
659     setLocInfo(ArgLocs, Ins);
660 
661     CallReturnHandler Handler(MIRBuilder, MF.getRegInfo(), MIB);
662     if (!Handler.handle(ArgLocs, ArgInfos))
663       return false;
664   }
665 
666   MIRBuilder.buildInstr(Mips::ADJCALLSTACKUP).addImm(NextStackOffset).addImm(0);
667 
668   return true;
669 }
670 
671 template <typename T>
672 void MipsCallLowering::subTargetRegTypeForCallingConv(
673     const Function &F, ArrayRef<ArgInfo> Args,
674     ArrayRef<unsigned> OrigArgIndices, SmallVectorImpl<T> &ISDArgs) const {
675   const DataLayout &DL = F.getParent()->getDataLayout();
676   const MipsTargetLowering &TLI = *getTLI<MipsTargetLowering>();
677 
678   unsigned ArgNo = 0;
679   for (auto &Arg : Args) {
680 
681     EVT VT = TLI.getValueType(DL, Arg.Ty);
682     MVT RegisterVT = TLI.getRegisterTypeForCallingConv(F.getContext(),
683                                                        F.getCallingConv(), VT);
684     unsigned NumRegs = TLI.getNumRegistersForCallingConv(
685         F.getContext(), F.getCallingConv(), VT);
686 
687     for (unsigned i = 0; i < NumRegs; ++i) {
688       ISD::ArgFlagsTy Flags = Arg.Flags[0];
689 
690       if (i == 0)
691         Flags.setOrigAlign(TLI.getABIAlignmentForCallingConv(Arg.Ty, DL));
692       else
693         Flags.setOrigAlign(Align::None());
694 
695       ISDArgs.emplace_back(Flags, RegisterVT, VT, true, OrigArgIndices[ArgNo],
696                            0);
697     }
698     ++ArgNo;
699   }
700 }
701 
702 void MipsCallLowering::splitToValueTypes(
703     const DataLayout &DL, const ArgInfo &OrigArg, unsigned OriginalIndex,
704     SmallVectorImpl<ArgInfo> &SplitArgs,
705     SmallVectorImpl<unsigned> &SplitArgsOrigIndices) const {
706 
707   SmallVector<EVT, 4> SplitEVTs;
708   SmallVector<Register, 4> SplitVRegs;
709   const MipsTargetLowering &TLI = *getTLI<MipsTargetLowering>();
710   LLVMContext &Ctx = OrigArg.Ty->getContext();
711 
712   ComputeValueVTs(TLI, DL, OrigArg.Ty, SplitEVTs);
713 
714   for (unsigned i = 0; i < SplitEVTs.size(); ++i) {
715     ArgInfo Info = ArgInfo{OrigArg.Regs[i], SplitEVTs[i].getTypeForEVT(Ctx)};
716     Info.Flags = OrigArg.Flags;
717     SplitArgs.push_back(Info);
718     SplitArgsOrigIndices.push_back(OriginalIndex);
719   }
720 }
721