CGCall.cpp revision 208600 
1//===----- CGCall.h - Encapsulate calling convention details ----*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// These classes wrap the information about a call or function
11// definition used to handle ABI compliancy.
12//
13//===----------------------------------------------------------------------===//
14
15#include "CGCall.h"
16#include "CodeGenFunction.h"
17#include "CodeGenModule.h"
18#include "clang/Basic/TargetInfo.h"
19#include "clang/AST/Decl.h"
20#include "clang/AST/DeclCXX.h"
21#include "clang/AST/DeclObjC.h"
22#include "clang/CodeGen/CodeGenOptions.h"
23#include "llvm/Attributes.h"
24#include "llvm/Support/CallSite.h"
25#include "llvm/Target/TargetData.h"
26
27#include "ABIInfo.h"
28
29using namespace clang;
30using namespace CodeGen;
31
32/***/
33
34// FIXME: Use iterator and sidestep silly type array creation.
35
36static unsigned ClangCallConvToLLVMCallConv(CallingConv CC) {
37  switch (CC) {
38  default: return llvm::CallingConv::C;
39  case CC_X86StdCall: return llvm::CallingConv::X86_StdCall;
40  case CC_X86FastCall: return llvm::CallingConv::X86_FastCall;
41  case CC_X86ThisCall: return llvm::CallingConv::X86_ThisCall;
42  }
43}
44
45/// Derives the 'this' type for codegen purposes, i.e. ignoring method
46/// qualification.
47/// FIXME: address space qualification?
48static CanQualType GetThisType(ASTContext &Context, const CXXRecordDecl *RD) {
49  QualType RecTy = Context.getTagDeclType(RD)->getCanonicalTypeInternal();
50  return Context.getPointerType(CanQualType::CreateUnsafe(RecTy));
51}
52
53/// Returns the canonical formal type of the given C++ method.
54static CanQual<FunctionProtoType> GetFormalType(const CXXMethodDecl *MD) {
55  return MD->getType()->getCanonicalTypeUnqualified()
56           .getAs<FunctionProtoType>();
57}
58
59/// Returns the "extra-canonicalized" return type, which discards
60/// qualifiers on the return type.  Codegen doesn't care about them,
61/// and it makes ABI code a little easier to be able to assume that
62/// all parameter and return types are top-level unqualified.
63static CanQualType GetReturnType(QualType RetTy) {
64  return RetTy->getCanonicalTypeUnqualified().getUnqualifiedType();
65}
66
67const CGFunctionInfo &
68CodeGenTypes::getFunctionInfo(CanQual<FunctionNoProtoType> FTNP) {
69  return getFunctionInfo(FTNP->getResultType().getUnqualifiedType(),
70                         llvm::SmallVector<CanQualType, 16>(),
71                         FTNP->getExtInfo());
72}
73
74/// \param Args - contains any initial parameters besides those
75///   in the formal type
76static const CGFunctionInfo &getFunctionInfo(CodeGenTypes &CGT,
77                                  llvm::SmallVectorImpl<CanQualType> &ArgTys,
78                                             CanQual<FunctionProtoType> FTP) {
79  // FIXME: Kill copy.
80  for (unsigned i = 0, e = FTP->getNumArgs(); i != e; ++i)
81    ArgTys.push_back(FTP->getArgType(i));
82  CanQualType ResTy = FTP->getResultType().getUnqualifiedType();
83  return CGT.getFunctionInfo(ResTy, ArgTys,
84                             FTP->getExtInfo());
85}
86
87const CGFunctionInfo &
88CodeGenTypes::getFunctionInfo(CanQual<FunctionProtoType> FTP) {
89  llvm::SmallVector<CanQualType, 16> ArgTys;
90  return ::getFunctionInfo(*this, ArgTys, FTP);
91}
92
93static CallingConv getCallingConventionForDecl(const Decl *D) {
94  // Set the appropriate calling convention for the Function.
95  if (D->hasAttr<StdCallAttr>())
96    return CC_X86StdCall;
97
98  if (D->hasAttr<FastCallAttr>())
99    return CC_X86FastCall;
100
101  if (D->hasAttr<ThisCallAttr>())
102    return CC_X86ThisCall;
103
104  return CC_C;
105}
106
107const CGFunctionInfo &CodeGenTypes::getFunctionInfo(const CXXRecordDecl *RD,
108                                                 const FunctionProtoType *FTP) {
109  llvm::SmallVector<CanQualType, 16> ArgTys;
110
111  // Add the 'this' pointer.
112  ArgTys.push_back(GetThisType(Context, RD));
113
114  return ::getFunctionInfo(*this, ArgTys,
115              FTP->getCanonicalTypeUnqualified().getAs<FunctionProtoType>());
116}
117
118const CGFunctionInfo &CodeGenTypes::getFunctionInfo(const CXXMethodDecl *MD) {
119  llvm::SmallVector<CanQualType, 16> ArgTys;
120
121  // Add the 'this' pointer unless this is a static method.
122  if (MD->isInstance())
123    ArgTys.push_back(GetThisType(Context, MD->getParent()));
124
125  return ::getFunctionInfo(*this, ArgTys, GetFormalType(MD));
126}
127
128const CGFunctionInfo &CodeGenTypes::getFunctionInfo(const CXXConstructorDecl *D,
129                                                    CXXCtorType Type) {
130  llvm::SmallVector<CanQualType, 16> ArgTys;
131
132  // Add the 'this' pointer.
133  ArgTys.push_back(GetThisType(Context, D->getParent()));
134
135  // Check if we need to add a VTT parameter (which has type void **).
136  if (Type == Ctor_Base && D->getParent()->getNumVBases() != 0)
137    ArgTys.push_back(Context.getPointerType(Context.VoidPtrTy));
138
139  return ::getFunctionInfo(*this, ArgTys, GetFormalType(D));
140}
141
142const CGFunctionInfo &CodeGenTypes::getFunctionInfo(const CXXDestructorDecl *D,
143                                                    CXXDtorType Type) {
144  llvm::SmallVector<CanQualType, 16> ArgTys;
145
146  // Add the 'this' pointer.
147  ArgTys.push_back(GetThisType(Context, D->getParent()));
148
149  // Check if we need to add a VTT parameter (which has type void **).
150  if (Type == Dtor_Base && D->getParent()->getNumVBases() != 0)
151    ArgTys.push_back(Context.getPointerType(Context.VoidPtrTy));
152
153  return ::getFunctionInfo(*this, ArgTys, GetFormalType(D));
154}
155
156const CGFunctionInfo &CodeGenTypes::getFunctionInfo(const FunctionDecl *FD) {
157  if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD))
158    if (MD->isInstance())
159      return getFunctionInfo(MD);
160
161  CanQualType FTy = FD->getType()->getCanonicalTypeUnqualified();
162  assert(isa<FunctionType>(FTy));
163  if (isa<FunctionNoProtoType>(FTy))
164    return getFunctionInfo(FTy.getAs<FunctionNoProtoType>());
165  assert(isa<FunctionProtoType>(FTy));
166  return getFunctionInfo(FTy.getAs<FunctionProtoType>());
167}
168
169const CGFunctionInfo &CodeGenTypes::getFunctionInfo(const ObjCMethodDecl *MD) {
170  llvm::SmallVector<CanQualType, 16> ArgTys;
171  ArgTys.push_back(Context.getCanonicalParamType(MD->getSelfDecl()->getType()));
172  ArgTys.push_back(Context.getCanonicalParamType(Context.getObjCSelType()));
173  // FIXME: Kill copy?
174  for (ObjCMethodDecl::param_iterator i = MD->param_begin(),
175         e = MD->param_end(); i != e; ++i) {
176    ArgTys.push_back(Context.getCanonicalParamType((*i)->getType()));
177  }
178  return getFunctionInfo(GetReturnType(MD->getResultType()),
179                         ArgTys,
180                         FunctionType::ExtInfo(
181                             /*NoReturn*/ false,
182                             /*RegParm*/ 0,
183                             getCallingConventionForDecl(MD)));
184}
185
186const CGFunctionInfo &CodeGenTypes::getFunctionInfo(GlobalDecl GD) {
187  // FIXME: Do we need to handle ObjCMethodDecl?
188  const FunctionDecl *FD = cast<FunctionDecl>(GD.getDecl());
189
190  if (const CXXConstructorDecl *CD = dyn_cast<CXXConstructorDecl>(FD))
191    return getFunctionInfo(CD, GD.getCtorType());
192
193  if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(FD))
194    return getFunctionInfo(DD, GD.getDtorType());
195
196  return getFunctionInfo(FD);
197}
198
199const CGFunctionInfo &CodeGenTypes::getFunctionInfo(QualType ResTy,
200                                                    const CallArgList &Args,
201                                            const FunctionType::ExtInfo &Info) {
202  // FIXME: Kill copy.
203  llvm::SmallVector<CanQualType, 16> ArgTys;
204  for (CallArgList::const_iterator i = Args.begin(), e = Args.end();
205       i != e; ++i)
206    ArgTys.push_back(Context.getCanonicalParamType(i->second));
207  return getFunctionInfo(GetReturnType(ResTy), ArgTys, Info);
208}
209
210const CGFunctionInfo &CodeGenTypes::getFunctionInfo(QualType ResTy,
211                                                    const FunctionArgList &Args,
212                                            const FunctionType::ExtInfo &Info) {
213  // FIXME: Kill copy.
214  llvm::SmallVector<CanQualType, 16> ArgTys;
215  for (FunctionArgList::const_iterator i = Args.begin(), e = Args.end();
216       i != e; ++i)
217    ArgTys.push_back(Context.getCanonicalParamType(i->second));
218  return getFunctionInfo(GetReturnType(ResTy), ArgTys, Info);
219}
220
221const CGFunctionInfo &CodeGenTypes::getFunctionInfo(CanQualType ResTy,
222                           const llvm::SmallVectorImpl<CanQualType> &ArgTys,
223                                            const FunctionType::ExtInfo &Info) {
224#ifndef NDEBUG
225  for (llvm::SmallVectorImpl<CanQualType>::const_iterator
226         I = ArgTys.begin(), E = ArgTys.end(); I != E; ++I)
227    assert(I->isCanonicalAsParam());
228#endif
229
230  unsigned CC = ClangCallConvToLLVMCallConv(Info.getCC());
231
232  // Lookup or create unique function info.
233  llvm::FoldingSetNodeID ID;
234  CGFunctionInfo::Profile(ID, Info, ResTy,
235                          ArgTys.begin(), ArgTys.end());
236
237  void *InsertPos = 0;
238  CGFunctionInfo *FI = FunctionInfos.FindNodeOrInsertPos(ID, InsertPos);
239  if (FI)
240    return *FI;
241
242  // Construct the function info.
243  FI = new CGFunctionInfo(CC, Info.getNoReturn(), Info.getRegParm(), ResTy, ArgTys);
244  FunctionInfos.InsertNode(FI, InsertPos);
245
246  // Compute ABI information.
247  getABIInfo().computeInfo(*FI, getContext(), TheModule.getContext());
248
249  return *FI;
250}
251
252CGFunctionInfo::CGFunctionInfo(unsigned _CallingConvention,
253                               bool _NoReturn,
254                               unsigned _RegParm,
255                               CanQualType ResTy,
256                               const llvm::SmallVectorImpl<CanQualType> &ArgTys)
257  : CallingConvention(_CallingConvention),
258    EffectiveCallingConvention(_CallingConvention),
259    NoReturn(_NoReturn), RegParm(_RegParm)
260{
261  NumArgs = ArgTys.size();
262  Args = new ArgInfo[1 + NumArgs];
263  Args[0].type = ResTy;
264  for (unsigned i = 0; i < NumArgs; ++i)
265    Args[1 + i].type = ArgTys[i];
266}
267
268/***/
269
270void CodeGenTypes::GetExpandedTypes(QualType Ty,
271                                    std::vector<const llvm::Type*> &ArgTys) {
272  const RecordType *RT = Ty->getAsStructureType();
273  assert(RT && "Can only expand structure types.");
274  const RecordDecl *RD = RT->getDecl();
275  assert(!RD->hasFlexibleArrayMember() &&
276         "Cannot expand structure with flexible array.");
277
278  for (RecordDecl::field_iterator i = RD->field_begin(), e = RD->field_end();
279         i != e; ++i) {
280    const FieldDecl *FD = *i;
281    assert(!FD->isBitField() &&
282           "Cannot expand structure with bit-field members.");
283
284    QualType FT = FD->getType();
285    if (CodeGenFunction::hasAggregateLLVMType(FT)) {
286      GetExpandedTypes(FT, ArgTys);
287    } else {
288      ArgTys.push_back(ConvertType(FT));
289    }
290  }
291}
292
293llvm::Function::arg_iterator
294CodeGenFunction::ExpandTypeFromArgs(QualType Ty, LValue LV,
295                                    llvm::Function::arg_iterator AI) {
296  const RecordType *RT = Ty->getAsStructureType();
297  assert(RT && "Can only expand structure types.");
298
299  RecordDecl *RD = RT->getDecl();
300  assert(LV.isSimple() &&
301         "Unexpected non-simple lvalue during struct expansion.");
302  llvm::Value *Addr = LV.getAddress();
303  for (RecordDecl::field_iterator i = RD->field_begin(), e = RD->field_end();
304         i != e; ++i) {
305    FieldDecl *FD = *i;
306    QualType FT = FD->getType();
307
308    // FIXME: What are the right qualifiers here?
309    LValue LV = EmitLValueForField(Addr, FD, 0);
310    if (CodeGenFunction::hasAggregateLLVMType(FT)) {
311      AI = ExpandTypeFromArgs(FT, LV, AI);
312    } else {
313      EmitStoreThroughLValue(RValue::get(AI), LV, FT);
314      ++AI;
315    }
316  }
317
318  return AI;
319}
320
321void
322CodeGenFunction::ExpandTypeToArgs(QualType Ty, RValue RV,
323                                  llvm::SmallVector<llvm::Value*, 16> &Args) {
324  const RecordType *RT = Ty->getAsStructureType();
325  assert(RT && "Can only expand structure types.");
326
327  RecordDecl *RD = RT->getDecl();
328  assert(RV.isAggregate() && "Unexpected rvalue during struct expansion");
329  llvm::Value *Addr = RV.getAggregateAddr();
330  for (RecordDecl::field_iterator i = RD->field_begin(), e = RD->field_end();
331         i != e; ++i) {
332    FieldDecl *FD = *i;
333    QualType FT = FD->getType();
334
335    // FIXME: What are the right qualifiers here?
336    LValue LV = EmitLValueForField(Addr, FD, 0);
337    if (CodeGenFunction::hasAggregateLLVMType(FT)) {
338      ExpandTypeToArgs(FT, RValue::getAggregate(LV.getAddress()), Args);
339    } else {
340      RValue RV = EmitLoadOfLValue(LV, FT);
341      assert(RV.isScalar() &&
342             "Unexpected non-scalar rvalue during struct expansion.");
343      Args.push_back(RV.getScalarVal());
344    }
345  }
346}
347
348/// CreateCoercedLoad - Create a load from \arg SrcPtr interpreted as
349/// a pointer to an object of type \arg Ty.
350///
351/// This safely handles the case when the src type is smaller than the
352/// destination type; in this situation the values of bits which not
353/// present in the src are undefined.
354static llvm::Value *CreateCoercedLoad(llvm::Value *SrcPtr,
355                                      const llvm::Type *Ty,
356                                      CodeGenFunction &CGF) {
357  const llvm::Type *SrcTy =
358    cast<llvm::PointerType>(SrcPtr->getType())->getElementType();
359  uint64_t SrcSize = CGF.CGM.getTargetData().getTypeAllocSize(SrcTy);
360  uint64_t DstSize = CGF.CGM.getTargetData().getTypeAllocSize(Ty);
361
362  // If load is legal, just bitcast the src pointer.
363  if (SrcSize >= DstSize) {
364    // Generally SrcSize is never greater than DstSize, since this means we are
365    // losing bits. However, this can happen in cases where the structure has
366    // additional padding, for example due to a user specified alignment.
367    //
368    // FIXME: Assert that we aren't truncating non-padding bits when have access
369    // to that information.
370    llvm::Value *Casted =
371      CGF.Builder.CreateBitCast(SrcPtr, llvm::PointerType::getUnqual(Ty));
372    llvm::LoadInst *Load = CGF.Builder.CreateLoad(Casted);
373    // FIXME: Use better alignment / avoid requiring aligned load.
374    Load->setAlignment(1);
375    return Load;
376  } else {
377    // Otherwise do coercion through memory. This is stupid, but
378    // simple.
379    llvm::Value *Tmp = CGF.CreateTempAlloca(Ty);
380    llvm::Value *Casted =
381      CGF.Builder.CreateBitCast(Tmp, llvm::PointerType::getUnqual(SrcTy));
382    llvm::StoreInst *Store =
383      CGF.Builder.CreateStore(CGF.Builder.CreateLoad(SrcPtr), Casted);
384    // FIXME: Use better alignment / avoid requiring aligned store.
385    Store->setAlignment(1);
386    return CGF.Builder.CreateLoad(Tmp);
387  }
388}
389
390/// CreateCoercedStore - Create a store to \arg DstPtr from \arg Src,
391/// where the source and destination may have different types.
392///
393/// This safely handles the case when the src type is larger than the
394/// destination type; the upper bits of the src will be lost.
395static void CreateCoercedStore(llvm::Value *Src,
396                               llvm::Value *DstPtr,
397                               bool DstIsVolatile,
398                               CodeGenFunction &CGF) {
399  const llvm::Type *SrcTy = Src->getType();
400  const llvm::Type *DstTy =
401    cast<llvm::PointerType>(DstPtr->getType())->getElementType();
402
403  uint64_t SrcSize = CGF.CGM.getTargetData().getTypeAllocSize(SrcTy);
404  uint64_t DstSize = CGF.CGM.getTargetData().getTypeAllocSize(DstTy);
405
406  // If store is legal, just bitcast the src pointer.
407  if (SrcSize <= DstSize) {
408    llvm::Value *Casted =
409      CGF.Builder.CreateBitCast(DstPtr, llvm::PointerType::getUnqual(SrcTy));
410    // FIXME: Use better alignment / avoid requiring aligned store.
411    CGF.Builder.CreateStore(Src, Casted, DstIsVolatile)->setAlignment(1);
412  } else {
413    // Otherwise do coercion through memory. This is stupid, but
414    // simple.
415
416    // Generally SrcSize is never greater than DstSize, since this means we are
417    // losing bits. However, this can happen in cases where the structure has
418    // additional padding, for example due to a user specified alignment.
419    //
420    // FIXME: Assert that we aren't truncating non-padding bits when have access
421    // to that information.
422    llvm::Value *Tmp = CGF.CreateTempAlloca(SrcTy);
423    CGF.Builder.CreateStore(Src, Tmp);
424    llvm::Value *Casted =
425      CGF.Builder.CreateBitCast(Tmp, llvm::PointerType::getUnqual(DstTy));
426    llvm::LoadInst *Load = CGF.Builder.CreateLoad(Casted);
427    // FIXME: Use better alignment / avoid requiring aligned load.
428    Load->setAlignment(1);
429    CGF.Builder.CreateStore(Load, DstPtr, DstIsVolatile);
430  }
431}
432
433/***/
434
435bool CodeGenModule::ReturnTypeUsesSret(const CGFunctionInfo &FI) {
436  return FI.getReturnInfo().isIndirect();
437}
438
439const llvm::FunctionType *CodeGenTypes::GetFunctionType(GlobalDecl GD) {
440  const CGFunctionInfo &FI = getFunctionInfo(GD);
441
442  // For definition purposes, don't consider a K&R function variadic.
443  bool Variadic = false;
444  if (const FunctionProtoType *FPT =
445        cast<FunctionDecl>(GD.getDecl())->getType()->getAs<FunctionProtoType>())
446    Variadic = FPT->isVariadic();
447
448  return GetFunctionType(FI, Variadic);
449}
450
451const llvm::FunctionType *
452CodeGenTypes::GetFunctionType(const CGFunctionInfo &FI, bool IsVariadic) {
453  std::vector<const llvm::Type*> ArgTys;
454
455  const llvm::Type *ResultType = 0;
456
457  QualType RetTy = FI.getReturnType();
458  const ABIArgInfo &RetAI = FI.getReturnInfo();
459  switch (RetAI.getKind()) {
460  case ABIArgInfo::Expand:
461    assert(0 && "Invalid ABI kind for return argument");
462
463  case ABIArgInfo::Extend:
464  case ABIArgInfo::Direct:
465    ResultType = ConvertType(RetTy);
466    break;
467
468  case ABIArgInfo::Indirect: {
469    assert(!RetAI.getIndirectAlign() && "Align unused on indirect return.");
470    ResultType = llvm::Type::getVoidTy(getLLVMContext());
471    const llvm::Type *STy = ConvertType(RetTy);
472    ArgTys.push_back(llvm::PointerType::get(STy, RetTy.getAddressSpace()));
473    break;
474  }
475
476  case ABIArgInfo::Ignore:
477    ResultType = llvm::Type::getVoidTy(getLLVMContext());
478    break;
479
480  case ABIArgInfo::Coerce:
481    ResultType = RetAI.getCoerceToType();
482    break;
483  }
484
485  for (CGFunctionInfo::const_arg_iterator it = FI.arg_begin(),
486         ie = FI.arg_end(); it != ie; ++it) {
487    const ABIArgInfo &AI = it->info;
488
489    switch (AI.getKind()) {
490    case ABIArgInfo::Ignore:
491      break;
492
493    case ABIArgInfo::Coerce:
494      ArgTys.push_back(AI.getCoerceToType());
495      break;
496
497    case ABIArgInfo::Indirect: {
498      // indirect arguments are always on the stack, which is addr space #0.
499      const llvm::Type *LTy = ConvertTypeForMem(it->type);
500      ArgTys.push_back(llvm::PointerType::getUnqual(LTy));
501      break;
502    }
503
504    case ABIArgInfo::Extend:
505    case ABIArgInfo::Direct:
506      ArgTys.push_back(ConvertType(it->type));
507      break;
508
509    case ABIArgInfo::Expand:
510      GetExpandedTypes(it->type, ArgTys);
511      break;
512    }
513  }
514
515  return llvm::FunctionType::get(ResultType, ArgTys, IsVariadic);
516}
517
518static bool HasIncompleteReturnTypeOrArgumentTypes(const FunctionProtoType *T) {
519  if (const TagType *TT = T->getResultType()->getAs<TagType>()) {
520    if (!TT->getDecl()->isDefinition())
521      return true;
522  }
523
524  for (unsigned i = 0, e = T->getNumArgs(); i != e; ++i) {
525    if (const TagType *TT = T->getArgType(i)->getAs<TagType>()) {
526      if (!TT->getDecl()->isDefinition())
527        return true;
528    }
529  }
530
531  return false;
532}
533
534const llvm::Type *
535CodeGenTypes::GetFunctionTypeForVTable(const CXXMethodDecl *MD) {
536  const FunctionProtoType *FPT = MD->getType()->getAs<FunctionProtoType>();
537
538  if (!HasIncompleteReturnTypeOrArgumentTypes(FPT))
539    return GetFunctionType(getFunctionInfo(MD), FPT->isVariadic());
540
541  return llvm::OpaqueType::get(getLLVMContext());
542}
543
544void CodeGenModule::ConstructAttributeList(const CGFunctionInfo &FI,
545                                           const Decl *TargetDecl,
546                                           AttributeListType &PAL,
547                                           unsigned &CallingConv) {
548  unsigned FuncAttrs = 0;
549  unsigned RetAttrs = 0;
550
551  CallingConv = FI.getEffectiveCallingConvention();
552
553  if (FI.isNoReturn())
554    FuncAttrs |= llvm::Attribute::NoReturn;
555
556  // FIXME: handle sseregparm someday...
557  if (TargetDecl) {
558    if (TargetDecl->hasAttr<NoThrowAttr>())
559      FuncAttrs |= llvm::Attribute::NoUnwind;
560    if (TargetDecl->hasAttr<NoReturnAttr>())
561      FuncAttrs |= llvm::Attribute::NoReturn;
562    if (TargetDecl->hasAttr<ConstAttr>())
563      FuncAttrs |= llvm::Attribute::ReadNone;
564    else if (TargetDecl->hasAttr<PureAttr>())
565      FuncAttrs |= llvm::Attribute::ReadOnly;
566    if (TargetDecl->hasAttr<MallocAttr>())
567      RetAttrs |= llvm::Attribute::NoAlias;
568  }
569
570  if (CodeGenOpts.OptimizeSize)
571    FuncAttrs |= llvm::Attribute::OptimizeForSize;
572  if (CodeGenOpts.DisableRedZone)
573    FuncAttrs |= llvm::Attribute::NoRedZone;
574  if (CodeGenOpts.NoImplicitFloat)
575    FuncAttrs |= llvm::Attribute::NoImplicitFloat;
576
577  QualType RetTy = FI.getReturnType();
578  unsigned Index = 1;
579  const ABIArgInfo &RetAI = FI.getReturnInfo();
580  switch (RetAI.getKind()) {
581  case ABIArgInfo::Extend:
582   if (RetTy->isSignedIntegerType()) {
583     RetAttrs |= llvm::Attribute::SExt;
584   } else if (RetTy->isUnsignedIntegerType()) {
585     RetAttrs |= llvm::Attribute::ZExt;
586   }
587   // FALLTHROUGH
588  case ABIArgInfo::Direct:
589    break;
590
591  case ABIArgInfo::Indirect:
592    PAL.push_back(llvm::AttributeWithIndex::get(Index,
593                                                llvm::Attribute::StructRet));
594    ++Index;
595    // sret disables readnone and readonly
596    FuncAttrs &= ~(llvm::Attribute::ReadOnly |
597                   llvm::Attribute::ReadNone);
598    break;
599
600  case ABIArgInfo::Ignore:
601  case ABIArgInfo::Coerce:
602    break;
603
604  case ABIArgInfo::Expand:
605    assert(0 && "Invalid ABI kind for return argument");
606  }
607
608  if (RetAttrs)
609    PAL.push_back(llvm::AttributeWithIndex::get(0, RetAttrs));
610
611  // FIXME: we need to honour command line settings also...
612  // FIXME: RegParm should be reduced in case of nested functions and/or global
613  // register variable.
614  signed RegParm = FI.getRegParm();
615
616  unsigned PointerWidth = getContext().Target.getPointerWidth(0);
617  for (CGFunctionInfo::const_arg_iterator it = FI.arg_begin(),
618         ie = FI.arg_end(); it != ie; ++it) {
619    QualType ParamType = it->type;
620    const ABIArgInfo &AI = it->info;
621    unsigned Attributes = 0;
622
623    // 'restrict' -> 'noalias' is done in EmitFunctionProlog when we
624    // have the corresponding parameter variable.  It doesn't make
625    // sense to do it here because parameters are so fucked up.
626
627    switch (AI.getKind()) {
628    case ABIArgInfo::Coerce:
629      break;
630
631    case ABIArgInfo::Indirect:
632      if (AI.getIndirectByVal())
633        Attributes |= llvm::Attribute::ByVal;
634
635      Attributes |=
636        llvm::Attribute::constructAlignmentFromInt(AI.getIndirectAlign());
637      // byval disables readnone and readonly.
638      FuncAttrs &= ~(llvm::Attribute::ReadOnly |
639                     llvm::Attribute::ReadNone);
640      break;
641
642    case ABIArgInfo::Extend:
643     if (ParamType->isSignedIntegerType()) {
644       Attributes |= llvm::Attribute::SExt;
645     } else if (ParamType->isUnsignedIntegerType()) {
646       Attributes |= llvm::Attribute::ZExt;
647     }
648     // FALLS THROUGH
649    case ABIArgInfo::Direct:
650      if (RegParm > 0 &&
651          (ParamType->isIntegerType() || ParamType->isPointerType())) {
652        RegParm -=
653          (Context.getTypeSize(ParamType) + PointerWidth - 1) / PointerWidth;
654        if (RegParm >= 0)
655          Attributes |= llvm::Attribute::InReg;
656      }
657      // FIXME: handle sseregparm someday...
658      break;
659
660    case ABIArgInfo::Ignore:
661      // Skip increment, no matching LLVM parameter.
662      continue;
663
664    case ABIArgInfo::Expand: {
665      std::vector<const llvm::Type*> Tys;
666      // FIXME: This is rather inefficient. Do we ever actually need to do
667      // anything here? The result should be just reconstructed on the other
668      // side, so extension should be a non-issue.
669      getTypes().GetExpandedTypes(ParamType, Tys);
670      Index += Tys.size();
671      continue;
672    }
673    }
674
675    if (Attributes)
676      PAL.push_back(llvm::AttributeWithIndex::get(Index, Attributes));
677    ++Index;
678  }
679  if (FuncAttrs)
680    PAL.push_back(llvm::AttributeWithIndex::get(~0, FuncAttrs));
681}
682
683void CodeGenFunction::EmitFunctionProlog(const CGFunctionInfo &FI,
684                                         llvm::Function *Fn,
685                                         const FunctionArgList &Args) {
686  // If this is an implicit-return-zero function, go ahead and
687  // initialize the return value.  TODO: it might be nice to have
688  // a more general mechanism for this that didn't require synthesized
689  // return statements.
690  if (const FunctionDecl* FD = dyn_cast_or_null<FunctionDecl>(CurFuncDecl)) {
691    if (FD->hasImplicitReturnZero()) {
692      QualType RetTy = FD->getResultType().getUnqualifiedType();
693      const llvm::Type* LLVMTy = CGM.getTypes().ConvertType(RetTy);
694      llvm::Constant* Zero = llvm::Constant::getNullValue(LLVMTy);
695      Builder.CreateStore(Zero, ReturnValue);
696    }
697  }
698
699  // FIXME: We no longer need the types from FunctionArgList; lift up and
700  // simplify.
701
702  // Emit allocs for param decls.  Give the LLVM Argument nodes names.
703  llvm::Function::arg_iterator AI = Fn->arg_begin();
704
705  // Name the struct return argument.
706  if (CGM.ReturnTypeUsesSret(FI)) {
707    AI->setName("agg.result");
708    ++AI;
709  }
710
711  assert(FI.arg_size() == Args.size() &&
712         "Mismatch between function signature & arguments.");
713  CGFunctionInfo::const_arg_iterator info_it = FI.arg_begin();
714  for (FunctionArgList::const_iterator i = Args.begin(), e = Args.end();
715       i != e; ++i, ++info_it) {
716    const VarDecl *Arg = i->first;
717    QualType Ty = info_it->type;
718    const ABIArgInfo &ArgI = info_it->info;
719
720    switch (ArgI.getKind()) {
721    case ABIArgInfo::Indirect: {
722      llvm::Value* V = AI;
723      if (hasAggregateLLVMType(Ty)) {
724        // Do nothing, aggregates and complex variables are accessed by
725        // reference.
726      } else {
727        // Load scalar value from indirect argument.
728        V = EmitLoadOfScalar(V, false, Ty);
729        if (!getContext().typesAreCompatible(Ty, Arg->getType())) {
730          // This must be a promotion, for something like
731          // "void a(x) short x; {..."
732          V = EmitScalarConversion(V, Ty, Arg->getType());
733        }
734      }
735      EmitParmDecl(*Arg, V);
736      break;
737    }
738
739    case ABIArgInfo::Extend:
740    case ABIArgInfo::Direct: {
741      assert(AI != Fn->arg_end() && "Argument mismatch!");
742      llvm::Value* V = AI;
743      if (hasAggregateLLVMType(Ty)) {
744        // Create a temporary alloca to hold the argument; the rest of
745        // codegen expects to access aggregates & complex values by
746        // reference.
747        V = CreateMemTemp(Ty);
748        Builder.CreateStore(AI, V);
749      } else {
750        if (Arg->getType().isRestrictQualified())
751          AI->addAttr(llvm::Attribute::NoAlias);
752
753        if (!getContext().typesAreCompatible(Ty, Arg->getType())) {
754          // This must be a promotion, for something like
755          // "void a(x) short x; {..."
756          V = EmitScalarConversion(V, Ty, Arg->getType());
757        }
758      }
759      EmitParmDecl(*Arg, V);
760      break;
761    }
762
763    case ABIArgInfo::Expand: {
764      // If this structure was expanded into multiple arguments then
765      // we need to create a temporary and reconstruct it from the
766      // arguments.
767      llvm::Value *Temp = CreateMemTemp(Ty, Arg->getName() + ".addr");
768      // FIXME: What are the right qualifiers here?
769      llvm::Function::arg_iterator End =
770        ExpandTypeFromArgs(Ty, LValue::MakeAddr(Temp, Qualifiers()), AI);
771      EmitParmDecl(*Arg, Temp);
772
773      // Name the arguments used in expansion and increment AI.
774      unsigned Index = 0;
775      for (; AI != End; ++AI, ++Index)
776        AI->setName(Arg->getName() + "." + llvm::Twine(Index));
777      continue;
778    }
779
780    case ABIArgInfo::Ignore:
781      // Initialize the local variable appropriately.
782      if (hasAggregateLLVMType(Ty)) {
783        EmitParmDecl(*Arg, CreateMemTemp(Ty));
784      } else {
785        EmitParmDecl(*Arg, llvm::UndefValue::get(ConvertType(Arg->getType())));
786      }
787
788      // Skip increment, no matching LLVM parameter.
789      continue;
790
791    case ABIArgInfo::Coerce: {
792      assert(AI != Fn->arg_end() && "Argument mismatch!");
793      // FIXME: This is very wasteful; EmitParmDecl is just going to drop the
794      // result in a new alloca anyway, so we could just store into that
795      // directly if we broke the abstraction down more.
796      llvm::Value *V = CreateMemTemp(Ty, "coerce");
797      CreateCoercedStore(AI, V, /*DestIsVolatile=*/false, *this);
798      // Match to what EmitParmDecl is expecting for this type.
799      if (!CodeGenFunction::hasAggregateLLVMType(Ty)) {
800        V = EmitLoadOfScalar(V, false, Ty);
801        if (!getContext().typesAreCompatible(Ty, Arg->getType())) {
802          // This must be a promotion, for something like
803          // "void a(x) short x; {..."
804          V = EmitScalarConversion(V, Ty, Arg->getType());
805        }
806      }
807      EmitParmDecl(*Arg, V);
808      break;
809    }
810    }
811
812    ++AI;
813  }
814  assert(AI == Fn->arg_end() && "Argument mismatch!");
815}
816
817void CodeGenFunction::EmitFunctionEpilog(const CGFunctionInfo &FI,
818                                         llvm::Value *ReturnValue) {
819  llvm::Value *RV = 0;
820
821  // Functions with no result always return void.
822  if (ReturnValue) {
823    QualType RetTy = FI.getReturnType();
824    const ABIArgInfo &RetAI = FI.getReturnInfo();
825
826    switch (RetAI.getKind()) {
827    case ABIArgInfo::Indirect:
828      if (RetTy->isAnyComplexType()) {
829        ComplexPairTy RT = LoadComplexFromAddr(ReturnValue, false);
830        StoreComplexToAddr(RT, CurFn->arg_begin(), false);
831      } else if (CodeGenFunction::hasAggregateLLVMType(RetTy)) {
832        // Do nothing; aggregrates get evaluated directly into the destination.
833      } else {
834        EmitStoreOfScalar(Builder.CreateLoad(ReturnValue), CurFn->arg_begin(),
835                          false, RetTy);
836      }
837      break;
838
839    case ABIArgInfo::Extend:
840    case ABIArgInfo::Direct:
841      // The internal return value temp always will have
842      // pointer-to-return-type type.
843      RV = Builder.CreateLoad(ReturnValue);
844      break;
845
846    case ABIArgInfo::Ignore:
847      break;
848
849    case ABIArgInfo::Coerce:
850      RV = CreateCoercedLoad(ReturnValue, RetAI.getCoerceToType(), *this);
851      break;
852
853    case ABIArgInfo::Expand:
854      assert(0 && "Invalid ABI kind for return argument");
855    }
856  }
857
858  if (RV) {
859    Builder.CreateRet(RV);
860  } else {
861    Builder.CreateRetVoid();
862  }
863}
864
865RValue CodeGenFunction::EmitDelegateCallArg(const VarDecl *Param) {
866  // StartFunction converted the ABI-lowered parameter(s) into a
867  // local alloca.  We need to turn that into an r-value suitable
868  // for EmitCall.
869  llvm::Value *Local = GetAddrOfLocalVar(Param);
870
871  QualType ArgType = Param->getType();
872
873  // For the most part, we just need to load the alloca, except:
874  // 1) aggregate r-values are actually pointers to temporaries, and
875  // 2) references to aggregates are pointers directly to the aggregate.
876  // I don't know why references to non-aggregates are different here.
877  if (const ReferenceType *RefType = ArgType->getAs<ReferenceType>()) {
878    if (hasAggregateLLVMType(RefType->getPointeeType()))
879      return RValue::getAggregate(Local);
880
881    // Locals which are references to scalars are represented
882    // with allocas holding the pointer.
883    return RValue::get(Builder.CreateLoad(Local));
884  }
885
886  if (ArgType->isAnyComplexType())
887    return RValue::getComplex(LoadComplexFromAddr(Local, /*volatile*/ false));
888
889  if (hasAggregateLLVMType(ArgType))
890    return RValue::getAggregate(Local);
891
892  return RValue::get(EmitLoadOfScalar(Local, false, ArgType));
893}
894
895RValue CodeGenFunction::EmitCallArg(const Expr *E, QualType ArgType) {
896  if (ArgType->isReferenceType())
897    return EmitReferenceBindingToExpr(E);
898
899  return EmitAnyExprToTemp(E);
900}
901
902RValue CodeGenFunction::EmitCall(const CGFunctionInfo &CallInfo,
903                                 llvm::Value *Callee,
904                                 ReturnValueSlot ReturnValue,
905                                 const CallArgList &CallArgs,
906                                 const Decl *TargetDecl,
907                                 llvm::Instruction **callOrInvoke) {
908  // FIXME: We no longer need the types from CallArgs; lift up and simplify.
909  llvm::SmallVector<llvm::Value*, 16> Args;
910
911  // Handle struct-return functions by passing a pointer to the
912  // location that we would like to return into.
913  QualType RetTy = CallInfo.getReturnType();
914  const ABIArgInfo &RetAI = CallInfo.getReturnInfo();
915
916
917  // If the call returns a temporary with struct return, create a temporary
918  // alloca to hold the result, unless one is given to us.
919  if (CGM.ReturnTypeUsesSret(CallInfo)) {
920    llvm::Value *Value = ReturnValue.getValue();
921    if (!Value)
922      Value = CreateMemTemp(RetTy);
923    Args.push_back(Value);
924  }
925
926  assert(CallInfo.arg_size() == CallArgs.size() &&
927         "Mismatch between function signature & arguments.");
928  CGFunctionInfo::const_arg_iterator info_it = CallInfo.arg_begin();
929  for (CallArgList::const_iterator I = CallArgs.begin(), E = CallArgs.end();
930       I != E; ++I, ++info_it) {
931    const ABIArgInfo &ArgInfo = info_it->info;
932    RValue RV = I->first;
933
934    switch (ArgInfo.getKind()) {
935    case ABIArgInfo::Indirect:
936      if (RV.isScalar() || RV.isComplex()) {
937        // Make a temporary alloca to pass the argument.
938        Args.push_back(CreateMemTemp(I->second));
939        if (RV.isScalar())
940          EmitStoreOfScalar(RV.getScalarVal(), Args.back(), false, I->second);
941        else
942          StoreComplexToAddr(RV.getComplexVal(), Args.back(), false);
943      } else {
944        Args.push_back(RV.getAggregateAddr());
945      }
946      break;
947
948    case ABIArgInfo::Extend:
949    case ABIArgInfo::Direct:
950      if (RV.isScalar()) {
951        Args.push_back(RV.getScalarVal());
952      } else if (RV.isComplex()) {
953        llvm::Value *Tmp = llvm::UndefValue::get(ConvertType(I->second));
954        Tmp = Builder.CreateInsertValue(Tmp, RV.getComplexVal().first, 0);
955        Tmp = Builder.CreateInsertValue(Tmp, RV.getComplexVal().second, 1);
956        Args.push_back(Tmp);
957      } else {
958        Args.push_back(Builder.CreateLoad(RV.getAggregateAddr()));
959      }
960      break;
961
962    case ABIArgInfo::Ignore:
963      break;
964
965    case ABIArgInfo::Coerce: {
966      // FIXME: Avoid the conversion through memory if possible.
967      llvm::Value *SrcPtr;
968      if (RV.isScalar()) {
969        SrcPtr = CreateMemTemp(I->second, "coerce");
970        EmitStoreOfScalar(RV.getScalarVal(), SrcPtr, false, I->second);
971      } else if (RV.isComplex()) {
972        SrcPtr = CreateMemTemp(I->second, "coerce");
973        StoreComplexToAddr(RV.getComplexVal(), SrcPtr, false);
974      } else
975        SrcPtr = RV.getAggregateAddr();
976      Args.push_back(CreateCoercedLoad(SrcPtr, ArgInfo.getCoerceToType(),
977                                       *this));
978      break;
979    }
980
981    case ABIArgInfo::Expand:
982      ExpandTypeToArgs(I->second, RV, Args);
983      break;
984    }
985  }
986
987  // If the callee is a bitcast of a function to a varargs pointer to function
988  // type, check to see if we can remove the bitcast.  This handles some cases
989  // with unprototyped functions.
990  if (llvm::ConstantExpr *CE = dyn_cast<llvm::ConstantExpr>(Callee))
991    if (llvm::Function *CalleeF = dyn_cast<llvm::Function>(CE->getOperand(0))) {
992      const llvm::PointerType *CurPT=cast<llvm::PointerType>(Callee->getType());
993      const llvm::FunctionType *CurFT =
994        cast<llvm::FunctionType>(CurPT->getElementType());
995      const llvm::FunctionType *ActualFT = CalleeF->getFunctionType();
996
997      if (CE->getOpcode() == llvm::Instruction::BitCast &&
998          ActualFT->getReturnType() == CurFT->getReturnType() &&
999          ActualFT->getNumParams() == CurFT->getNumParams() &&
1000          ActualFT->getNumParams() == Args.size()) {
1001        bool ArgsMatch = true;
1002        for (unsigned i = 0, e = ActualFT->getNumParams(); i != e; ++i)
1003          if (ActualFT->getParamType(i) != CurFT->getParamType(i)) {
1004            ArgsMatch = false;
1005            break;
1006          }
1007
1008        // Strip the cast if we can get away with it.  This is a nice cleanup,
1009        // but also allows us to inline the function at -O0 if it is marked
1010        // always_inline.
1011        if (ArgsMatch)
1012          Callee = CalleeF;
1013      }
1014    }
1015
1016
1017  llvm::BasicBlock *InvokeDest = getInvokeDest();
1018  unsigned CallingConv;
1019  CodeGen::AttributeListType AttributeList;
1020  CGM.ConstructAttributeList(CallInfo, TargetDecl, AttributeList, CallingConv);
1021  llvm::AttrListPtr Attrs = llvm::AttrListPtr::get(AttributeList.begin(),
1022                                                   AttributeList.end());
1023
1024  llvm::CallSite CS;
1025  if (!InvokeDest || (Attrs.getFnAttributes() & llvm::Attribute::NoUnwind)) {
1026    CS = Builder.CreateCall(Callee, Args.data(), Args.data()+Args.size());
1027  } else {
1028    llvm::BasicBlock *Cont = createBasicBlock("invoke.cont");
1029    CS = Builder.CreateInvoke(Callee, Cont, InvokeDest,
1030                              Args.data(), Args.data()+Args.size());
1031    EmitBlock(Cont);
1032  }
1033  if (callOrInvoke) {
1034    *callOrInvoke = CS.getInstruction();
1035  }
1036
1037  CS.setAttributes(Attrs);
1038  CS.setCallingConv(static_cast<llvm::CallingConv::ID>(CallingConv));
1039
1040  // If the call doesn't return, finish the basic block and clear the
1041  // insertion point; this allows the rest of IRgen to discard
1042  // unreachable code.
1043  if (CS.doesNotReturn()) {
1044    Builder.CreateUnreachable();
1045    Builder.ClearInsertionPoint();
1046
1047    // FIXME: For now, emit a dummy basic block because expr emitters in
1048    // generally are not ready to handle emitting expressions at unreachable
1049    // points.
1050    EnsureInsertPoint();
1051
1052    // Return a reasonable RValue.
1053    return GetUndefRValue(RetTy);
1054  }
1055
1056  llvm::Instruction *CI = CS.getInstruction();
1057  if (Builder.isNamePreserving() && !CI->getType()->isVoidTy())
1058    CI->setName("call");
1059
1060  switch (RetAI.getKind()) {
1061  case ABIArgInfo::Indirect:
1062    if (RetTy->isAnyComplexType())
1063      return RValue::getComplex(LoadComplexFromAddr(Args[0], false));
1064    if (CodeGenFunction::hasAggregateLLVMType(RetTy))
1065      return RValue::getAggregate(Args[0]);
1066    return RValue::get(EmitLoadOfScalar(Args[0], false, RetTy));
1067
1068  case ABIArgInfo::Extend:
1069  case ABIArgInfo::Direct:
1070    if (RetTy->isAnyComplexType()) {
1071      llvm::Value *Real = Builder.CreateExtractValue(CI, 0);
1072      llvm::Value *Imag = Builder.CreateExtractValue(CI, 1);
1073      return RValue::getComplex(std::make_pair(Real, Imag));
1074    }
1075    if (CodeGenFunction::hasAggregateLLVMType(RetTy)) {
1076      llvm::Value *DestPtr = ReturnValue.getValue();
1077      bool DestIsVolatile = ReturnValue.isVolatile();
1078
1079      if (!DestPtr) {
1080        DestPtr = CreateMemTemp(RetTy, "agg.tmp");
1081        DestIsVolatile = false;
1082      }
1083      Builder.CreateStore(CI, DestPtr, DestIsVolatile);
1084      return RValue::getAggregate(DestPtr);
1085    }
1086    return RValue::get(CI);
1087
1088  case ABIArgInfo::Ignore:
1089    // If we are ignoring an argument that had a result, make sure to
1090    // construct the appropriate return value for our caller.
1091    return GetUndefRValue(RetTy);
1092
1093  case ABIArgInfo::Coerce: {
1094    llvm::Value *DestPtr = ReturnValue.getValue();
1095    bool DestIsVolatile = ReturnValue.isVolatile();
1096
1097    if (!DestPtr) {
1098      DestPtr = CreateMemTemp(RetTy, "coerce");
1099      DestIsVolatile = false;
1100    }
1101
1102    CreateCoercedStore(CI, DestPtr, DestIsVolatile, *this);
1103    if (RetTy->isAnyComplexType())
1104      return RValue::getComplex(LoadComplexFromAddr(DestPtr, false));
1105    if (CodeGenFunction::hasAggregateLLVMType(RetTy))
1106      return RValue::getAggregate(DestPtr);
1107    return RValue::get(EmitLoadOfScalar(DestPtr, false, RetTy));
1108  }
1109
1110  case ABIArgInfo::Expand:
1111    assert(0 && "Invalid ABI kind for return argument");
1112  }
1113
1114  assert(0 && "Unhandled ABIArgInfo::Kind");
1115  return RValue::get(0);
1116}
1117
1118/* VarArg handling */
1119
1120llvm::Value *CodeGenFunction::EmitVAArg(llvm::Value *VAListAddr, QualType Ty) {
1121  return CGM.getTypes().getABIInfo().EmitVAArg(VAListAddr, Ty, *this);
1122}
1123