CGCall.cpp revision 046c294a43024874ff35656c6e785b64e72f1f36 
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  }
42}
43
44/// Derives the 'this' type for codegen purposes, i.e. ignoring method
45/// qualification.
46/// FIXME: address space qualification?
47static CanQualType GetThisType(ASTContext &Context, const CXXRecordDecl *RD) {
48  QualType RecTy = Context.getTagDeclType(RD)->getCanonicalTypeInternal();
49  return Context.getPointerType(CanQualType::CreateUnsafe(RecTy));
50}
51
52/// Returns the canonical formal type of the given C++ method.
53static CanQual<FunctionProtoType> GetFormalType(const CXXMethodDecl *MD) {
54  return MD->getType()->getCanonicalTypeUnqualified()
55           .getAs<FunctionProtoType>();
56}
57
58/// Returns the "extra-canonicalized" return type, which discards
59/// qualifiers on the return type.  Codegen doesn't care about them,
60/// and it makes ABI code a little easier to be able to assume that
61/// all parameter and return types are top-level unqualified.
62static CanQualType GetReturnType(QualType RetTy) {
63  return RetTy->getCanonicalTypeUnqualified().getUnqualifiedType();
64}
65
66const CGFunctionInfo &
67CodeGenTypes::getFunctionInfo(CanQual<FunctionNoProtoType> FTNP) {
68  return getFunctionInfo(FTNP->getResultType().getUnqualifiedType(),
69                         llvm::SmallVector<CanQualType, 16>(),
70                         FTNP->getExtInfo());
71}
72
73/// \param Args - contains any initial parameters besides those
74///   in the formal type
75static const CGFunctionInfo &getFunctionInfo(CodeGenTypes &CGT,
76                                  llvm::SmallVectorImpl<CanQualType> &ArgTys,
77                                             CanQual<FunctionProtoType> FTP) {
78  // FIXME: Kill copy.
79  for (unsigned i = 0, e = FTP->getNumArgs(); i != e; ++i)
80    ArgTys.push_back(FTP->getArgType(i));
81  CanQualType ResTy = FTP->getResultType().getUnqualifiedType();
82  return CGT.getFunctionInfo(ResTy, ArgTys,
83                             FTP->getExtInfo());
84}
85
86const CGFunctionInfo &
87CodeGenTypes::getFunctionInfo(CanQual<FunctionProtoType> FTP) {
88  llvm::SmallVector<CanQualType, 16> ArgTys;
89  return ::getFunctionInfo(*this, ArgTys, FTP);
90}
91
92static CallingConv getCallingConventionForDecl(const Decl *D) {
93  // Set the appropriate calling convention for the Function.
94  if (D->hasAttr<StdCallAttr>())
95    return CC_X86StdCall;
96
97  if (D->hasAttr<FastCallAttr>())
98    return CC_X86FastCall;
99
100  return CC_C;
101}
102
103const CGFunctionInfo &CodeGenTypes::getFunctionInfo(const CXXRecordDecl *RD,
104                                                 const FunctionProtoType *FTP) {
105  llvm::SmallVector<CanQualType, 16> ArgTys;
106
107  // Add the 'this' pointer.
108  ArgTys.push_back(GetThisType(Context, RD));
109
110  return ::getFunctionInfo(*this, ArgTys,
111              FTP->getCanonicalTypeUnqualified().getAs<FunctionProtoType>());
112}
113
114const CGFunctionInfo &CodeGenTypes::getFunctionInfo(const CXXMethodDecl *MD) {
115  llvm::SmallVector<CanQualType, 16> ArgTys;
116
117  // Add the 'this' pointer unless this is a static method.
118  if (MD->isInstance())
119    ArgTys.push_back(GetThisType(Context, MD->getParent()));
120
121  return ::getFunctionInfo(*this, ArgTys, GetFormalType(MD));
122}
123
124const CGFunctionInfo &CodeGenTypes::getFunctionInfo(const CXXConstructorDecl *D,
125                                                    CXXCtorType Type) {
126  llvm::SmallVector<CanQualType, 16> ArgTys;
127
128  // Add the 'this' pointer.
129  ArgTys.push_back(GetThisType(Context, D->getParent()));
130
131  // Check if we need to add a VTT parameter (which has type void **).
132  if (Type == Ctor_Base && D->getParent()->getNumVBases() != 0)
133    ArgTys.push_back(Context.getPointerType(Context.VoidPtrTy));
134
135  return ::getFunctionInfo(*this, ArgTys, GetFormalType(D));
136}
137
138const CGFunctionInfo &CodeGenTypes::getFunctionInfo(const CXXDestructorDecl *D,
139                                                    CXXDtorType Type) {
140  llvm::SmallVector<CanQualType, 16> ArgTys;
141
142  // Add the 'this' pointer.
143  ArgTys.push_back(GetThisType(Context, D->getParent()));
144
145  // Check if we need to add a VTT parameter (which has type void **).
146  if (Type == Dtor_Base && D->getParent()->getNumVBases() != 0)
147    ArgTys.push_back(Context.getPointerType(Context.VoidPtrTy));
148
149  return ::getFunctionInfo(*this, ArgTys, GetFormalType(D));
150}
151
152const CGFunctionInfo &CodeGenTypes::getFunctionInfo(const FunctionDecl *FD) {
153  if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD))
154    if (MD->isInstance())
155      return getFunctionInfo(MD);
156
157  CanQualType FTy = FD->getType()->getCanonicalTypeUnqualified();
158  assert(isa<FunctionType>(FTy));
159  if (isa<FunctionNoProtoType>(FTy))
160    return getFunctionInfo(FTy.getAs<FunctionNoProtoType>());
161  assert(isa<FunctionProtoType>(FTy));
162  return getFunctionInfo(FTy.getAs<FunctionProtoType>());
163}
164
165const CGFunctionInfo &CodeGenTypes::getFunctionInfo(const ObjCMethodDecl *MD) {
166  llvm::SmallVector<CanQualType, 16> ArgTys;
167  ArgTys.push_back(Context.getCanonicalParamType(MD->getSelfDecl()->getType()));
168  ArgTys.push_back(Context.getCanonicalParamType(Context.getObjCSelType()));
169  // FIXME: Kill copy?
170  for (ObjCMethodDecl::param_iterator i = MD->param_begin(),
171         e = MD->param_end(); i != e; ++i) {
172    ArgTys.push_back(Context.getCanonicalParamType((*i)->getType()));
173  }
174  return getFunctionInfo(GetReturnType(MD->getResultType()),
175                         ArgTys,
176                         FunctionType::ExtInfo(
177                             /*NoReturn*/ false,
178                             /*RegParm*/ 0,
179                             getCallingConventionForDecl(MD)));
180}
181
182const CGFunctionInfo &CodeGenTypes::getFunctionInfo(GlobalDecl GD) {
183  // FIXME: Do we need to handle ObjCMethodDecl?
184  const FunctionDecl *FD = cast<FunctionDecl>(GD.getDecl());
185
186  if (const CXXConstructorDecl *CD = dyn_cast<CXXConstructorDecl>(FD))
187    return getFunctionInfo(CD, GD.getCtorType());
188
189  if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(FD))
190    return getFunctionInfo(DD, GD.getDtorType());
191
192  return getFunctionInfo(FD);
193}
194
195const CGFunctionInfo &CodeGenTypes::getFunctionInfo(QualType ResTy,
196                                                    const CallArgList &Args,
197                                            const FunctionType::ExtInfo &Info) {
198  // FIXME: Kill copy.
199  llvm::SmallVector<CanQualType, 16> ArgTys;
200  for (CallArgList::const_iterator i = Args.begin(), e = Args.end();
201       i != e; ++i)
202    ArgTys.push_back(Context.getCanonicalParamType(i->second));
203  return getFunctionInfo(GetReturnType(ResTy), ArgTys, Info);
204}
205
206const CGFunctionInfo &CodeGenTypes::getFunctionInfo(QualType ResTy,
207                                                    const FunctionArgList &Args,
208                                            const FunctionType::ExtInfo &Info) {
209  // FIXME: Kill copy.
210  llvm::SmallVector<CanQualType, 16> ArgTys;
211  for (FunctionArgList::const_iterator i = Args.begin(), e = Args.end();
212       i != e; ++i)
213    ArgTys.push_back(Context.getCanonicalParamType(i->second));
214  return getFunctionInfo(GetReturnType(ResTy), ArgTys, Info);
215}
216
217const CGFunctionInfo &CodeGenTypes::getFunctionInfo(CanQualType ResTy,
218                           const llvm::SmallVectorImpl<CanQualType> &ArgTys,
219                                            const FunctionType::ExtInfo &Info) {
220#ifndef NDEBUG
221  for (llvm::SmallVectorImpl<CanQualType>::const_iterator
222         I = ArgTys.begin(), E = ArgTys.end(); I != E; ++I)
223    assert(I->isCanonicalAsParam());
224#endif
225
226  unsigned CC = ClangCallConvToLLVMCallConv(Info.getCC());
227
228  // Lookup or create unique function info.
229  llvm::FoldingSetNodeID ID;
230  CGFunctionInfo::Profile(ID, Info, ResTy,
231                          ArgTys.begin(), ArgTys.end());
232
233  void *InsertPos = 0;
234  CGFunctionInfo *FI = FunctionInfos.FindNodeOrInsertPos(ID, InsertPos);
235  if (FI)
236    return *FI;
237
238  // Construct the function info.
239  FI = new CGFunctionInfo(CC, Info.getNoReturn(), Info.getRegParm(), ResTy, ArgTys);
240  FunctionInfos.InsertNode(FI, InsertPos);
241
242  // Compute ABI information.
243  getABIInfo().computeInfo(*FI, getContext(), TheModule.getContext());
244
245  return *FI;
246}
247
248CGFunctionInfo::CGFunctionInfo(unsigned _CallingConvention,
249                               bool _NoReturn,
250                               unsigned _RegParm,
251                               CanQualType ResTy,
252                               const llvm::SmallVectorImpl<CanQualType> &ArgTys)
253  : CallingConvention(_CallingConvention),
254    EffectiveCallingConvention(_CallingConvention),
255    NoReturn(_NoReturn), RegParm(_RegParm)
256{
257  NumArgs = ArgTys.size();
258  Args = new ArgInfo[1 + NumArgs];
259  Args[0].type = ResTy;
260  for (unsigned i = 0; i < NumArgs; ++i)
261    Args[1 + i].type = ArgTys[i];
262}
263
264/***/
265
266void CodeGenTypes::GetExpandedTypes(QualType Ty,
267                                    std::vector<const llvm::Type*> &ArgTys) {
268  const RecordType *RT = Ty->getAsStructureType();
269  assert(RT && "Can only expand structure types.");
270  const RecordDecl *RD = RT->getDecl();
271  assert(!RD->hasFlexibleArrayMember() &&
272         "Cannot expand structure with flexible array.");
273
274  for (RecordDecl::field_iterator i = RD->field_begin(), e = RD->field_end();
275         i != e; ++i) {
276    const FieldDecl *FD = *i;
277    assert(!FD->isBitField() &&
278           "Cannot expand structure with bit-field members.");
279
280    QualType FT = FD->getType();
281    if (CodeGenFunction::hasAggregateLLVMType(FT)) {
282      GetExpandedTypes(FT, ArgTys);
283    } else {
284      ArgTys.push_back(ConvertType(FT));
285    }
286  }
287}
288
289llvm::Function::arg_iterator
290CodeGenFunction::ExpandTypeFromArgs(QualType Ty, LValue LV,
291                                    llvm::Function::arg_iterator AI) {
292  const RecordType *RT = Ty->getAsStructureType();
293  assert(RT && "Can only expand structure types.");
294
295  RecordDecl *RD = RT->getDecl();
296  assert(LV.isSimple() &&
297         "Unexpected non-simple lvalue during struct expansion.");
298  llvm::Value *Addr = LV.getAddress();
299  for (RecordDecl::field_iterator i = RD->field_begin(), e = RD->field_end();
300         i != e; ++i) {
301    FieldDecl *FD = *i;
302    QualType FT = FD->getType();
303
304    // FIXME: What are the right qualifiers here?
305    LValue LV = EmitLValueForField(Addr, FD, 0);
306    if (CodeGenFunction::hasAggregateLLVMType(FT)) {
307      AI = ExpandTypeFromArgs(FT, LV, AI);
308    } else {
309      EmitStoreThroughLValue(RValue::get(AI), LV, FT);
310      ++AI;
311    }
312  }
313
314  return AI;
315}
316
317void
318CodeGenFunction::ExpandTypeToArgs(QualType Ty, RValue RV,
319                                  llvm::SmallVector<llvm::Value*, 16> &Args) {
320  const RecordType *RT = Ty->getAsStructureType();
321  assert(RT && "Can only expand structure types.");
322
323  RecordDecl *RD = RT->getDecl();
324  assert(RV.isAggregate() && "Unexpected rvalue during struct expansion");
325  llvm::Value *Addr = RV.getAggregateAddr();
326  for (RecordDecl::field_iterator i = RD->field_begin(), e = RD->field_end();
327         i != e; ++i) {
328    FieldDecl *FD = *i;
329    QualType FT = FD->getType();
330
331    // FIXME: What are the right qualifiers here?
332    LValue LV = EmitLValueForField(Addr, FD, 0);
333    if (CodeGenFunction::hasAggregateLLVMType(FT)) {
334      ExpandTypeToArgs(FT, RValue::getAggregate(LV.getAddress()), Args);
335    } else {
336      RValue RV = EmitLoadOfLValue(LV, FT);
337      assert(RV.isScalar() &&
338             "Unexpected non-scalar rvalue during struct expansion.");
339      Args.push_back(RV.getScalarVal());
340    }
341  }
342}
343
344/// CreateCoercedLoad - Create a load from \arg SrcPtr interpreted as
345/// a pointer to an object of type \arg Ty.
346///
347/// This safely handles the case when the src type is smaller than the
348/// destination type; in this situation the values of bits which not
349/// present in the src are undefined.
350static llvm::Value *CreateCoercedLoad(llvm::Value *SrcPtr,
351                                      const llvm::Type *Ty,
352                                      CodeGenFunction &CGF) {
353  const llvm::Type *SrcTy =
354    cast<llvm::PointerType>(SrcPtr->getType())->getElementType();
355  uint64_t SrcSize = CGF.CGM.getTargetData().getTypeAllocSize(SrcTy);
356  uint64_t DstSize = CGF.CGM.getTargetData().getTypeAllocSize(Ty);
357
358  // If load is legal, just bitcast the src pointer.
359  if (SrcSize >= DstSize) {
360    // Generally SrcSize is never greater than DstSize, since this means we are
361    // losing bits. However, this can happen in cases where the structure has
362    // additional padding, for example due to a user specified alignment.
363    //
364    // FIXME: Assert that we aren't truncating non-padding bits when have access
365    // to that information.
366    llvm::Value *Casted =
367      CGF.Builder.CreateBitCast(SrcPtr, llvm::PointerType::getUnqual(Ty));
368    llvm::LoadInst *Load = CGF.Builder.CreateLoad(Casted);
369    // FIXME: Use better alignment / avoid requiring aligned load.
370    Load->setAlignment(1);
371    return Load;
372  } else {
373    // Otherwise do coercion through memory. This is stupid, but
374    // simple.
375    llvm::Value *Tmp = CGF.CreateTempAlloca(Ty);
376    llvm::Value *Casted =
377      CGF.Builder.CreateBitCast(Tmp, llvm::PointerType::getUnqual(SrcTy));
378    llvm::StoreInst *Store =
379      CGF.Builder.CreateStore(CGF.Builder.CreateLoad(SrcPtr), Casted);
380    // FIXME: Use better alignment / avoid requiring aligned store.
381    Store->setAlignment(1);
382    return CGF.Builder.CreateLoad(Tmp);
383  }
384}
385
386/// CreateCoercedStore - Create a store to \arg DstPtr from \arg Src,
387/// where the source and destination may have different types.
388///
389/// This safely handles the case when the src type is larger than the
390/// destination type; the upper bits of the src will be lost.
391static void CreateCoercedStore(llvm::Value *Src,
392                               llvm::Value *DstPtr,
393                               bool DstIsVolatile,
394                               CodeGenFunction &CGF) {
395  const llvm::Type *SrcTy = Src->getType();
396  const llvm::Type *DstTy =
397    cast<llvm::PointerType>(DstPtr->getType())->getElementType();
398
399  uint64_t SrcSize = CGF.CGM.getTargetData().getTypeAllocSize(SrcTy);
400  uint64_t DstSize = CGF.CGM.getTargetData().getTypeAllocSize(DstTy);
401
402  // If store is legal, just bitcast the src pointer.
403  if (SrcSize <= DstSize) {
404    llvm::Value *Casted =
405      CGF.Builder.CreateBitCast(DstPtr, llvm::PointerType::getUnqual(SrcTy));
406    // FIXME: Use better alignment / avoid requiring aligned store.
407    CGF.Builder.CreateStore(Src, Casted, DstIsVolatile)->setAlignment(1);
408  } else {
409    // Otherwise do coercion through memory. This is stupid, but
410    // simple.
411
412    // Generally SrcSize is never greater than DstSize, since this means we are
413    // losing bits. However, this can happen in cases where the structure has
414    // additional padding, for example due to a user specified alignment.
415    //
416    // FIXME: Assert that we aren't truncating non-padding bits when have access
417    // to that information.
418    llvm::Value *Tmp = CGF.CreateTempAlloca(SrcTy);
419    CGF.Builder.CreateStore(Src, Tmp);
420    llvm::Value *Casted =
421      CGF.Builder.CreateBitCast(Tmp, llvm::PointerType::getUnqual(DstTy));
422    llvm::LoadInst *Load = CGF.Builder.CreateLoad(Casted);
423    // FIXME: Use better alignment / avoid requiring aligned load.
424    Load->setAlignment(1);
425    CGF.Builder.CreateStore(Load, DstPtr, DstIsVolatile);
426  }
427}
428
429/***/
430
431bool CodeGenModule::ReturnTypeUsesSret(const CGFunctionInfo &FI) {
432  return FI.getReturnInfo().isIndirect();
433}
434
435const llvm::FunctionType *CodeGenTypes::GetFunctionType(GlobalDecl GD) {
436  const CGFunctionInfo &FI = getFunctionInfo(GD);
437
438  // For definition purposes, don't consider a K&R function variadic.
439  bool Variadic = false;
440  if (const FunctionProtoType *FPT =
441        cast<FunctionDecl>(GD.getDecl())->getType()->getAs<FunctionProtoType>())
442    Variadic = FPT->isVariadic();
443
444  return GetFunctionType(FI, Variadic);
445}
446
447const llvm::FunctionType *
448CodeGenTypes::GetFunctionType(const CGFunctionInfo &FI, bool IsVariadic) {
449  std::vector<const llvm::Type*> ArgTys;
450
451  const llvm::Type *ResultType = 0;
452
453  QualType RetTy = FI.getReturnType();
454  const ABIArgInfo &RetAI = FI.getReturnInfo();
455  switch (RetAI.getKind()) {
456  case ABIArgInfo::Expand:
457    assert(0 && "Invalid ABI kind for return argument");
458
459  case ABIArgInfo::Extend:
460  case ABIArgInfo::Direct:
461    ResultType = ConvertType(RetTy);
462    break;
463
464  case ABIArgInfo::Indirect: {
465    assert(!RetAI.getIndirectAlign() && "Align unused on indirect return.");
466    ResultType = llvm::Type::getVoidTy(getLLVMContext());
467    const llvm::Type *STy = ConvertType(RetTy);
468    ArgTys.push_back(llvm::PointerType::get(STy, RetTy.getAddressSpace()));
469    break;
470  }
471
472  case ABIArgInfo::Ignore:
473    ResultType = llvm::Type::getVoidTy(getLLVMContext());
474    break;
475
476  case ABIArgInfo::Coerce:
477    ResultType = RetAI.getCoerceToType();
478    break;
479  }
480
481  for (CGFunctionInfo::const_arg_iterator it = FI.arg_begin(),
482         ie = FI.arg_end(); it != ie; ++it) {
483    const ABIArgInfo &AI = it->info;
484
485    switch (AI.getKind()) {
486    case ABIArgInfo::Ignore:
487      break;
488
489    case ABIArgInfo::Coerce:
490      ArgTys.push_back(AI.getCoerceToType());
491      break;
492
493    case ABIArgInfo::Indirect: {
494      // indirect arguments are always on the stack, which is addr space #0.
495      const llvm::Type *LTy = ConvertTypeForMem(it->type);
496      ArgTys.push_back(llvm::PointerType::getUnqual(LTy));
497      break;
498    }
499
500    case ABIArgInfo::Extend:
501    case ABIArgInfo::Direct:
502      ArgTys.push_back(ConvertType(it->type));
503      break;
504
505    case ABIArgInfo::Expand:
506      GetExpandedTypes(it->type, ArgTys);
507      break;
508    }
509  }
510
511  return llvm::FunctionType::get(ResultType, ArgTys, IsVariadic);
512}
513
514static bool HasIncompleteReturnTypeOrArgumentTypes(const FunctionProtoType *T) {
515  if (const TagType *TT = T->getResultType()->getAs<TagType>()) {
516    if (!TT->getDecl()->isDefinition())
517      return true;
518  }
519
520  for (unsigned i = 0, e = T->getNumArgs(); i != e; ++i) {
521    if (const TagType *TT = T->getArgType(i)->getAs<TagType>()) {
522      if (!TT->getDecl()->isDefinition())
523        return true;
524    }
525  }
526
527  return false;
528}
529
530const llvm::Type *
531CodeGenTypes::GetFunctionTypeForVTable(const CXXMethodDecl *MD) {
532  const FunctionProtoType *FPT = MD->getType()->getAs<FunctionProtoType>();
533
534  if (!HasIncompleteReturnTypeOrArgumentTypes(FPT))
535    return GetFunctionType(getFunctionInfo(MD), FPT->isVariadic());
536
537  return llvm::OpaqueType::get(getLLVMContext());
538}
539
540void CodeGenModule::ConstructAttributeList(const CGFunctionInfo &FI,
541                                           const Decl *TargetDecl,
542                                           AttributeListType &PAL,
543                                           unsigned &CallingConv) {
544  unsigned FuncAttrs = 0;
545  unsigned RetAttrs = 0;
546
547  CallingConv = FI.getEffectiveCallingConvention();
548
549  if (FI.isNoReturn())
550    FuncAttrs |= llvm::Attribute::NoReturn;
551
552  // FIXME: handle sseregparm someday...
553  if (TargetDecl) {
554    if (TargetDecl->hasAttr<NoThrowAttr>())
555      FuncAttrs |= llvm::Attribute::NoUnwind;
556    if (TargetDecl->hasAttr<NoReturnAttr>())
557      FuncAttrs |= llvm::Attribute::NoReturn;
558    if (TargetDecl->hasAttr<ConstAttr>())
559      FuncAttrs |= llvm::Attribute::ReadNone;
560    else if (TargetDecl->hasAttr<PureAttr>())
561      FuncAttrs |= llvm::Attribute::ReadOnly;
562    if (TargetDecl->hasAttr<MallocAttr>())
563      RetAttrs |= llvm::Attribute::NoAlias;
564  }
565
566  if (CodeGenOpts.OptimizeSize)
567    FuncAttrs |= llvm::Attribute::OptimizeForSize;
568  if (CodeGenOpts.DisableRedZone)
569    FuncAttrs |= llvm::Attribute::NoRedZone;
570  if (CodeGenOpts.NoImplicitFloat)
571    FuncAttrs |= llvm::Attribute::NoImplicitFloat;
572
573  QualType RetTy = FI.getReturnType();
574  unsigned Index = 1;
575  const ABIArgInfo &RetAI = FI.getReturnInfo();
576  switch (RetAI.getKind()) {
577  case ABIArgInfo::Extend:
578   if (RetTy->isSignedIntegerType()) {
579     RetAttrs |= llvm::Attribute::SExt;
580   } else if (RetTy->isUnsignedIntegerType()) {
581     RetAttrs |= llvm::Attribute::ZExt;
582   }
583   // FALLTHROUGH
584  case ABIArgInfo::Direct:
585    break;
586
587  case ABIArgInfo::Indirect:
588    PAL.push_back(llvm::AttributeWithIndex::get(Index,
589                                                llvm::Attribute::StructRet |
590                                                llvm::Attribute::NoAlias));
591    ++Index;
592    // sret disables readnone and readonly
593    FuncAttrs &= ~(llvm::Attribute::ReadOnly |
594                   llvm::Attribute::ReadNone);
595    break;
596
597  case ABIArgInfo::Ignore:
598  case ABIArgInfo::Coerce:
599    break;
600
601  case ABIArgInfo::Expand:
602    assert(0 && "Invalid ABI kind for return argument");
603  }
604
605  if (RetAttrs)
606    PAL.push_back(llvm::AttributeWithIndex::get(0, RetAttrs));
607
608  // FIXME: we need to honour command line settings also...
609  // FIXME: RegParm should be reduced in case of nested functions and/or global
610  // register variable.
611  signed RegParm = FI.getRegParm();
612
613  unsigned PointerWidth = getContext().Target.getPointerWidth(0);
614  for (CGFunctionInfo::const_arg_iterator it = FI.arg_begin(),
615         ie = FI.arg_end(); it != ie; ++it) {
616    QualType ParamType = it->type;
617    const ABIArgInfo &AI = it->info;
618    unsigned Attributes = 0;
619
620    // 'restrict' -> 'noalias' is done in EmitFunctionProlog when we
621    // have the corresponding parameter variable.  It doesn't make
622    // sense to do it here because parameters are so fucked up.
623
624    switch (AI.getKind()) {
625    case ABIArgInfo::Coerce:
626      break;
627
628    case ABIArgInfo::Indirect:
629      if (AI.getIndirectByVal())
630        Attributes |= llvm::Attribute::ByVal;
631
632      Attributes |=
633        llvm::Attribute::constructAlignmentFromInt(AI.getIndirectAlign());
634      // byval disables readnone and readonly.
635      FuncAttrs &= ~(llvm::Attribute::ReadOnly |
636                     llvm::Attribute::ReadNone);
637      break;
638
639    case ABIArgInfo::Extend:
640     if (ParamType->isSignedIntegerType()) {
641       Attributes |= llvm::Attribute::SExt;
642     } else if (ParamType->isUnsignedIntegerType()) {
643       Attributes |= llvm::Attribute::ZExt;
644     }
645     // FALLS THROUGH
646    case ABIArgInfo::Direct:
647      if (RegParm > 0 &&
648          (ParamType->isIntegerType() || ParamType->isPointerType())) {
649        RegParm -=
650          (Context.getTypeSize(ParamType) + PointerWidth - 1) / PointerWidth;
651        if (RegParm >= 0)
652          Attributes |= llvm::Attribute::InReg;
653      }
654      // FIXME: handle sseregparm someday...
655      break;
656
657    case ABIArgInfo::Ignore:
658      // Skip increment, no matching LLVM parameter.
659      continue;
660
661    case ABIArgInfo::Expand: {
662      std::vector<const llvm::Type*> Tys;
663      // FIXME: This is rather inefficient. Do we ever actually need to do
664      // anything here? The result should be just reconstructed on the other
665      // side, so extension should be a non-issue.
666      getTypes().GetExpandedTypes(ParamType, Tys);
667      Index += Tys.size();
668      continue;
669    }
670    }
671
672    if (Attributes)
673      PAL.push_back(llvm::AttributeWithIndex::get(Index, Attributes));
674    ++Index;
675  }
676  if (FuncAttrs)
677    PAL.push_back(llvm::AttributeWithIndex::get(~0, FuncAttrs));
678}
679
680void CodeGenFunction::EmitFunctionProlog(const CGFunctionInfo &FI,
681                                         llvm::Function *Fn,
682                                         const FunctionArgList &Args) {
683  // If this is an implicit-return-zero function, go ahead and
684  // initialize the return value.  TODO: it might be nice to have
685  // a more general mechanism for this that didn't require synthesized
686  // return statements.
687  if (const FunctionDecl* FD = dyn_cast_or_null<FunctionDecl>(CurFuncDecl)) {
688    if (FD->hasImplicitReturnZero()) {
689      QualType RetTy = FD->getResultType().getUnqualifiedType();
690      const llvm::Type* LLVMTy = CGM.getTypes().ConvertType(RetTy);
691      llvm::Constant* Zero = llvm::Constant::getNullValue(LLVMTy);
692      Builder.CreateStore(Zero, ReturnValue);
693    }
694  }
695
696  // FIXME: We no longer need the types from FunctionArgList; lift up and
697  // simplify.
698
699  // Emit allocs for param decls.  Give the LLVM Argument nodes names.
700  llvm::Function::arg_iterator AI = Fn->arg_begin();
701
702  // Name the struct return argument.
703  if (CGM.ReturnTypeUsesSret(FI)) {
704    AI->setName("agg.result");
705    ++AI;
706  }
707
708  assert(FI.arg_size() == Args.size() &&
709         "Mismatch between function signature & arguments.");
710  CGFunctionInfo::const_arg_iterator info_it = FI.arg_begin();
711  for (FunctionArgList::const_iterator i = Args.begin(), e = Args.end();
712       i != e; ++i, ++info_it) {
713    const VarDecl *Arg = i->first;
714    QualType Ty = info_it->type;
715    const ABIArgInfo &ArgI = info_it->info;
716
717    switch (ArgI.getKind()) {
718    case ABIArgInfo::Indirect: {
719      llvm::Value* V = AI;
720      if (hasAggregateLLVMType(Ty)) {
721        // Do nothing, aggregates and complex variables are accessed by
722        // reference.
723      } else {
724        // Load scalar value from indirect argument.
725        V = EmitLoadOfScalar(V, false, Ty);
726        if (!getContext().typesAreCompatible(Ty, Arg->getType())) {
727          // This must be a promotion, for something like
728          // "void a(x) short x; {..."
729          V = EmitScalarConversion(V, Ty, Arg->getType());
730        }
731      }
732      EmitParmDecl(*Arg, V);
733      break;
734    }
735
736    case ABIArgInfo::Extend:
737    case ABIArgInfo::Direct: {
738      assert(AI != Fn->arg_end() && "Argument mismatch!");
739      llvm::Value* V = AI;
740      if (hasAggregateLLVMType(Ty)) {
741        // Create a temporary alloca to hold the argument; the rest of
742        // codegen expects to access aggregates & complex values by
743        // reference.
744        V = CreateMemTemp(Ty);
745        Builder.CreateStore(AI, V);
746      } else {
747        if (Arg->getType().isRestrictQualified())
748          AI->addAttr(llvm::Attribute::NoAlias);
749
750        if (!getContext().typesAreCompatible(Ty, Arg->getType())) {
751          // This must be a promotion, for something like
752          // "void a(x) short x; {..."
753          V = EmitScalarConversion(V, Ty, Arg->getType());
754        }
755      }
756      EmitParmDecl(*Arg, V);
757      break;
758    }
759
760    case ABIArgInfo::Expand: {
761      // If this structure was expanded into multiple arguments then
762      // we need to create a temporary and reconstruct it from the
763      // arguments.
764      llvm::Value *Temp = CreateMemTemp(Ty, Arg->getName() + ".addr");
765      // FIXME: What are the right qualifiers here?
766      llvm::Function::arg_iterator End =
767        ExpandTypeFromArgs(Ty, LValue::MakeAddr(Temp, Qualifiers()), AI);
768      EmitParmDecl(*Arg, Temp);
769
770      // Name the arguments used in expansion and increment AI.
771      unsigned Index = 0;
772      for (; AI != End; ++AI, ++Index)
773        AI->setName(Arg->getName() + "." + llvm::Twine(Index));
774      continue;
775    }
776
777    case ABIArgInfo::Ignore:
778      // Initialize the local variable appropriately.
779      if (hasAggregateLLVMType(Ty)) {
780        EmitParmDecl(*Arg, CreateMemTemp(Ty));
781      } else {
782        EmitParmDecl(*Arg, llvm::UndefValue::get(ConvertType(Arg->getType())));
783      }
784
785      // Skip increment, no matching LLVM parameter.
786      continue;
787
788    case ABIArgInfo::Coerce: {
789      assert(AI != Fn->arg_end() && "Argument mismatch!");
790      // FIXME: This is very wasteful; EmitParmDecl is just going to drop the
791      // result in a new alloca anyway, so we could just store into that
792      // directly if we broke the abstraction down more.
793      llvm::Value *V = CreateMemTemp(Ty, "coerce");
794      CreateCoercedStore(AI, V, /*DestIsVolatile=*/false, *this);
795      // Match to what EmitParmDecl is expecting for this type.
796      if (!CodeGenFunction::hasAggregateLLVMType(Ty)) {
797        V = EmitLoadOfScalar(V, false, Ty);
798        if (!getContext().typesAreCompatible(Ty, Arg->getType())) {
799          // This must be a promotion, for something like
800          // "void a(x) short x; {..."
801          V = EmitScalarConversion(V, Ty, Arg->getType());
802        }
803      }
804      EmitParmDecl(*Arg, V);
805      break;
806    }
807    }
808
809    ++AI;
810  }
811  assert(AI == Fn->arg_end() && "Argument mismatch!");
812}
813
814void CodeGenFunction::EmitFunctionEpilog(const CGFunctionInfo &FI,
815                                         llvm::Value *ReturnValue) {
816  llvm::Value *RV = 0;
817
818  // Functions with no result always return void.
819  if (ReturnValue) {
820    QualType RetTy = FI.getReturnType();
821    const ABIArgInfo &RetAI = FI.getReturnInfo();
822
823    switch (RetAI.getKind()) {
824    case ABIArgInfo::Indirect:
825      if (RetTy->isAnyComplexType()) {
826        ComplexPairTy RT = LoadComplexFromAddr(ReturnValue, false);
827        StoreComplexToAddr(RT, CurFn->arg_begin(), false);
828      } else if (CodeGenFunction::hasAggregateLLVMType(RetTy)) {
829        // Do nothing; aggregrates get evaluated directly into the destination.
830      } else {
831        EmitStoreOfScalar(Builder.CreateLoad(ReturnValue), CurFn->arg_begin(),
832                          false, RetTy);
833      }
834      break;
835
836    case ABIArgInfo::Extend:
837    case ABIArgInfo::Direct:
838      // The internal return value temp always will have
839      // pointer-to-return-type type.
840      RV = Builder.CreateLoad(ReturnValue);
841      break;
842
843    case ABIArgInfo::Ignore:
844      break;
845
846    case ABIArgInfo::Coerce:
847      RV = CreateCoercedLoad(ReturnValue, RetAI.getCoerceToType(), *this);
848      break;
849
850    case ABIArgInfo::Expand:
851      assert(0 && "Invalid ABI kind for return argument");
852    }
853  }
854
855  if (RV) {
856    Builder.CreateRet(RV);
857  } else {
858    Builder.CreateRetVoid();
859  }
860}
861
862RValue CodeGenFunction::EmitCallArg(const Expr *E, QualType ArgType) {
863  if (ArgType->isReferenceType())
864    return EmitReferenceBindingToExpr(E);
865
866  return EmitAnyExprToTemp(E);
867}
868
869RValue CodeGenFunction::EmitCall(const CGFunctionInfo &CallInfo,
870                                 llvm::Value *Callee,
871                                 ReturnValueSlot ReturnValue,
872                                 const CallArgList &CallArgs,
873                                 const Decl *TargetDecl) {
874  // FIXME: We no longer need the types from CallArgs; lift up and simplify.
875  llvm::SmallVector<llvm::Value*, 16> Args;
876
877  // Handle struct-return functions by passing a pointer to the
878  // location that we would like to return into.
879  QualType RetTy = CallInfo.getReturnType();
880  const ABIArgInfo &RetAI = CallInfo.getReturnInfo();
881
882
883  // If the call returns a temporary with struct return, create a temporary
884  // alloca to hold the result, unless one is given to us.
885  if (CGM.ReturnTypeUsesSret(CallInfo)) {
886    llvm::Value *Value = ReturnValue.getValue();
887    if (!Value)
888      Value = CreateMemTemp(RetTy);
889    Args.push_back(Value);
890  }
891
892  assert(CallInfo.arg_size() == CallArgs.size() &&
893         "Mismatch between function signature & arguments.");
894  CGFunctionInfo::const_arg_iterator info_it = CallInfo.arg_begin();
895  for (CallArgList::const_iterator I = CallArgs.begin(), E = CallArgs.end();
896       I != E; ++I, ++info_it) {
897    const ABIArgInfo &ArgInfo = info_it->info;
898    RValue RV = I->first;
899
900    switch (ArgInfo.getKind()) {
901    case ABIArgInfo::Indirect:
902      if (RV.isScalar() || RV.isComplex()) {
903        // Make a temporary alloca to pass the argument.
904        Args.push_back(CreateMemTemp(I->second));
905        if (RV.isScalar())
906          EmitStoreOfScalar(RV.getScalarVal(), Args.back(), false, I->second);
907        else
908          StoreComplexToAddr(RV.getComplexVal(), Args.back(), false);
909      } else {
910        Args.push_back(RV.getAggregateAddr());
911      }
912      break;
913
914    case ABIArgInfo::Extend:
915    case ABIArgInfo::Direct:
916      if (RV.isScalar()) {
917        Args.push_back(RV.getScalarVal());
918      } else if (RV.isComplex()) {
919        llvm::Value *Tmp = llvm::UndefValue::get(ConvertType(I->second));
920        Tmp = Builder.CreateInsertValue(Tmp, RV.getComplexVal().first, 0);
921        Tmp = Builder.CreateInsertValue(Tmp, RV.getComplexVal().second, 1);
922        Args.push_back(Tmp);
923      } else {
924        Args.push_back(Builder.CreateLoad(RV.getAggregateAddr()));
925      }
926      break;
927
928    case ABIArgInfo::Ignore:
929      break;
930
931    case ABIArgInfo::Coerce: {
932      // FIXME: Avoid the conversion through memory if possible.
933      llvm::Value *SrcPtr;
934      if (RV.isScalar()) {
935        SrcPtr = CreateMemTemp(I->second, "coerce");
936        EmitStoreOfScalar(RV.getScalarVal(), SrcPtr, false, I->second);
937      } else if (RV.isComplex()) {
938        SrcPtr = CreateMemTemp(I->second, "coerce");
939        StoreComplexToAddr(RV.getComplexVal(), SrcPtr, false);
940      } else
941        SrcPtr = RV.getAggregateAddr();
942      Args.push_back(CreateCoercedLoad(SrcPtr, ArgInfo.getCoerceToType(),
943                                       *this));
944      break;
945    }
946
947    case ABIArgInfo::Expand:
948      ExpandTypeToArgs(I->second, RV, Args);
949      break;
950    }
951  }
952
953  // If the callee is a bitcast of a function to a varargs pointer to function
954  // type, check to see if we can remove the bitcast.  This handles some cases
955  // with unprototyped functions.
956  if (llvm::ConstantExpr *CE = dyn_cast<llvm::ConstantExpr>(Callee))
957    if (llvm::Function *CalleeF = dyn_cast<llvm::Function>(CE->getOperand(0))) {
958      const llvm::PointerType *CurPT=cast<llvm::PointerType>(Callee->getType());
959      const llvm::FunctionType *CurFT =
960        cast<llvm::FunctionType>(CurPT->getElementType());
961      const llvm::FunctionType *ActualFT = CalleeF->getFunctionType();
962
963      if (CE->getOpcode() == llvm::Instruction::BitCast &&
964          ActualFT->getReturnType() == CurFT->getReturnType() &&
965          ActualFT->getNumParams() == CurFT->getNumParams() &&
966          ActualFT->getNumParams() == Args.size()) {
967        bool ArgsMatch = true;
968        for (unsigned i = 0, e = ActualFT->getNumParams(); i != e; ++i)
969          if (ActualFT->getParamType(i) != CurFT->getParamType(i)) {
970            ArgsMatch = false;
971            break;
972          }
973
974        // Strip the cast if we can get away with it.  This is a nice cleanup,
975        // but also allows us to inline the function at -O0 if it is marked
976        // always_inline.
977        if (ArgsMatch)
978          Callee = CalleeF;
979      }
980    }
981
982
983  llvm::BasicBlock *InvokeDest = getInvokeDest();
984  unsigned CallingConv;
985  CodeGen::AttributeListType AttributeList;
986  CGM.ConstructAttributeList(CallInfo, TargetDecl, AttributeList, CallingConv);
987  llvm::AttrListPtr Attrs = llvm::AttrListPtr::get(AttributeList.begin(),
988                                                   AttributeList.end());
989
990  llvm::CallSite CS;
991  if (!InvokeDest || (Attrs.getFnAttributes() & llvm::Attribute::NoUnwind)) {
992    CS = Builder.CreateCall(Callee, Args.data(), Args.data()+Args.size());
993  } else {
994    llvm::BasicBlock *Cont = createBasicBlock("invoke.cont");
995    CS = Builder.CreateInvoke(Callee, Cont, InvokeDest,
996                              Args.data(), Args.data()+Args.size());
997    EmitBlock(Cont);
998  }
999
1000  CS.setAttributes(Attrs);
1001  CS.setCallingConv(static_cast<llvm::CallingConv::ID>(CallingConv));
1002
1003  // If the call doesn't return, finish the basic block and clear the
1004  // insertion point; this allows the rest of IRgen to discard
1005  // unreachable code.
1006  if (CS.doesNotReturn()) {
1007    Builder.CreateUnreachable();
1008    Builder.ClearInsertionPoint();
1009
1010    // FIXME: For now, emit a dummy basic block because expr emitters in
1011    // generally are not ready to handle emitting expressions at unreachable
1012    // points.
1013    EnsureInsertPoint();
1014
1015    // Return a reasonable RValue.
1016    return GetUndefRValue(RetTy);
1017  }
1018
1019  llvm::Instruction *CI = CS.getInstruction();
1020  if (Builder.isNamePreserving() && !CI->getType()->isVoidTy())
1021    CI->setName("call");
1022
1023  switch (RetAI.getKind()) {
1024  case ABIArgInfo::Indirect:
1025    if (RetTy->isAnyComplexType())
1026      return RValue::getComplex(LoadComplexFromAddr(Args[0], false));
1027    if (CodeGenFunction::hasAggregateLLVMType(RetTy))
1028      return RValue::getAggregate(Args[0]);
1029    return RValue::get(EmitLoadOfScalar(Args[0], false, RetTy));
1030
1031  case ABIArgInfo::Extend:
1032  case ABIArgInfo::Direct:
1033    if (RetTy->isAnyComplexType()) {
1034      llvm::Value *Real = Builder.CreateExtractValue(CI, 0);
1035      llvm::Value *Imag = Builder.CreateExtractValue(CI, 1);
1036      return RValue::getComplex(std::make_pair(Real, Imag));
1037    }
1038    if (CodeGenFunction::hasAggregateLLVMType(RetTy)) {
1039      llvm::Value *DestPtr = ReturnValue.getValue();
1040      bool DestIsVolatile = ReturnValue.isVolatile();
1041
1042      if (!DestPtr) {
1043        DestPtr = CreateMemTemp(RetTy, "agg.tmp");
1044        DestIsVolatile = false;
1045      }
1046      Builder.CreateStore(CI, DestPtr, DestIsVolatile);
1047      return RValue::getAggregate(DestPtr);
1048    }
1049    return RValue::get(CI);
1050
1051  case ABIArgInfo::Ignore:
1052    // If we are ignoring an argument that had a result, make sure to
1053    // construct the appropriate return value for our caller.
1054    return GetUndefRValue(RetTy);
1055
1056  case ABIArgInfo::Coerce: {
1057    llvm::Value *DestPtr = ReturnValue.getValue();
1058    bool DestIsVolatile = ReturnValue.isVolatile();
1059
1060    if (!DestPtr) {
1061      DestPtr = CreateMemTemp(RetTy, "coerce");
1062      DestIsVolatile = false;
1063    }
1064
1065    CreateCoercedStore(CI, DestPtr, DestIsVolatile, *this);
1066    if (RetTy->isAnyComplexType())
1067      return RValue::getComplex(LoadComplexFromAddr(DestPtr, false));
1068    if (CodeGenFunction::hasAggregateLLVMType(RetTy))
1069      return RValue::getAggregate(DestPtr);
1070    return RValue::get(EmitLoadOfScalar(DestPtr, false, RetTy));
1071  }
1072
1073  case ABIArgInfo::Expand:
1074    assert(0 && "Invalid ABI kind for return argument");
1075  }
1076
1077  assert(0 && "Unhandled ABIArgInfo::Kind");
1078  return RValue::get(0);
1079}
1080
1081/* VarArg handling */
1082
1083llvm::Value *CodeGenFunction::EmitVAArg(llvm::Value *VAListAddr, QualType Ty) {
1084  return CGM.getTypes().getABIInfo().EmitVAArg(VAListAddr, Ty, *this);
1085}
1086