CGCall.cpp revision b5a03b6217cd6c3eecdc1aa4df03060cf51ac942 
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 "CGCXXABI.h"
17#include "ABIInfo.h"
18#include "CodeGenFunction.h"
19#include "CodeGenModule.h"
20#include "clang/Basic/TargetInfo.h"
21#include "clang/AST/Decl.h"
22#include "clang/AST/DeclCXX.h"
23#include "clang/AST/DeclObjC.h"
24#include "clang/Frontend/CodeGenOptions.h"
25#include "llvm/Attributes.h"
26#include "llvm/Support/CallSite.h"
27#include "llvm/Target/TargetData.h"
28using namespace clang;
29using namespace CodeGen;
30
31/***/
32
33static unsigned ClangCallConvToLLVMCallConv(CallingConv CC) {
34  switch (CC) {
35  default: return llvm::CallingConv::C;
36  case CC_X86StdCall: return llvm::CallingConv::X86_StdCall;
37  case CC_X86FastCall: return llvm::CallingConv::X86_FastCall;
38  case CC_X86ThisCall: return llvm::CallingConv::X86_ThisCall;
39  case CC_AAPCS: return llvm::CallingConv::ARM_AAPCS;
40  case CC_AAPCS_VFP: return llvm::CallingConv::ARM_AAPCS_VFP;
41  // TODO: add support for CC_X86Pascal to llvm
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                              bool IsRecursive) {
70  return getFunctionInfo(FTNP->getResultType().getUnqualifiedType(),
71                         llvm::SmallVector<CanQualType, 16>(),
72                         FTNP->getExtInfo(), IsRecursive);
73}
74
75/// \param Args - contains any initial parameters besides those
76///   in the formal type
77static const CGFunctionInfo &getFunctionInfo(CodeGenTypes &CGT,
78                                  llvm::SmallVectorImpl<CanQualType> &ArgTys,
79                                             CanQual<FunctionProtoType> FTP,
80                                             bool IsRecursive = false) {
81  // FIXME: Kill copy.
82  for (unsigned i = 0, e = FTP->getNumArgs(); i != e; ++i)
83    ArgTys.push_back(FTP->getArgType(i));
84  CanQualType ResTy = FTP->getResultType().getUnqualifiedType();
85  return CGT.getFunctionInfo(ResTy, ArgTys, FTP->getExtInfo(), IsRecursive);
86}
87
88const CGFunctionInfo &
89CodeGenTypes::getFunctionInfo(CanQual<FunctionProtoType> FTP,
90                              bool IsRecursive) {
91  llvm::SmallVector<CanQualType, 16> ArgTys;
92  return ::getFunctionInfo(*this, ArgTys, FTP, IsRecursive);
93}
94
95static CallingConv getCallingConventionForDecl(const Decl *D) {
96  // Set the appropriate calling convention for the Function.
97  if (D->hasAttr<StdCallAttr>())
98    return CC_X86StdCall;
99
100  if (D->hasAttr<FastCallAttr>())
101    return CC_X86FastCall;
102
103  if (D->hasAttr<ThisCallAttr>())
104    return CC_X86ThisCall;
105
106  if (D->hasAttr<PascalAttr>())
107    return CC_X86Pascal;
108
109  if (PcsAttr *PCS = D->getAttr<PcsAttr>())
110    return (PCS->getPCS() == PcsAttr::AAPCS ? CC_AAPCS : CC_AAPCS_VFP);
111
112  return CC_C;
113}
114
115const CGFunctionInfo &CodeGenTypes::getFunctionInfo(const CXXRecordDecl *RD,
116                                                 const FunctionProtoType *FTP) {
117  llvm::SmallVector<CanQualType, 16> ArgTys;
118
119  // Add the 'this' pointer.
120  ArgTys.push_back(GetThisType(Context, RD));
121
122  return ::getFunctionInfo(*this, ArgTys,
123              FTP->getCanonicalTypeUnqualified().getAs<FunctionProtoType>());
124}
125
126const CGFunctionInfo &CodeGenTypes::getFunctionInfo(const CXXMethodDecl *MD) {
127  llvm::SmallVector<CanQualType, 16> ArgTys;
128
129  assert(!isa<CXXConstructorDecl>(MD) && "wrong method for contructors!");
130  assert(!isa<CXXDestructorDecl>(MD) && "wrong method for destructors!");
131
132  // Add the 'this' pointer unless this is a static method.
133  if (MD->isInstance())
134    ArgTys.push_back(GetThisType(Context, MD->getParent()));
135
136  return ::getFunctionInfo(*this, ArgTys, GetFormalType(MD));
137}
138
139const CGFunctionInfo &CodeGenTypes::getFunctionInfo(const CXXConstructorDecl *D,
140                                                    CXXCtorType Type) {
141  llvm::SmallVector<CanQualType, 16> ArgTys;
142  ArgTys.push_back(GetThisType(Context, D->getParent()));
143  CanQualType ResTy = Context.VoidTy;
144
145  TheCXXABI.BuildConstructorSignature(D, Type, ResTy, ArgTys);
146
147  CanQual<FunctionProtoType> FTP = GetFormalType(D);
148
149  // Add the formal parameters.
150  for (unsigned i = 0, e = FTP->getNumArgs(); i != e; ++i)
151    ArgTys.push_back(FTP->getArgType(i));
152
153  return getFunctionInfo(ResTy, ArgTys, FTP->getExtInfo());
154}
155
156const CGFunctionInfo &CodeGenTypes::getFunctionInfo(const CXXDestructorDecl *D,
157                                                    CXXDtorType Type) {
158  llvm::SmallVector<CanQualType, 2> ArgTys;
159  ArgTys.push_back(GetThisType(Context, D->getParent()));
160  CanQualType ResTy = Context.VoidTy;
161
162  TheCXXABI.BuildDestructorSignature(D, Type, ResTy, ArgTys);
163
164  CanQual<FunctionProtoType> FTP = GetFormalType(D);
165  assert(FTP->getNumArgs() == 0 && "dtor with formal parameters");
166
167  return getFunctionInfo(ResTy, ArgTys, FTP->getExtInfo());
168}
169
170const CGFunctionInfo &CodeGenTypes::getFunctionInfo(const FunctionDecl *FD) {
171  if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD))
172    if (MD->isInstance())
173      return getFunctionInfo(MD);
174
175  CanQualType FTy = FD->getType()->getCanonicalTypeUnqualified();
176  assert(isa<FunctionType>(FTy));
177  if (isa<FunctionNoProtoType>(FTy))
178    return getFunctionInfo(FTy.getAs<FunctionNoProtoType>());
179  assert(isa<FunctionProtoType>(FTy));
180  return getFunctionInfo(FTy.getAs<FunctionProtoType>());
181}
182
183const CGFunctionInfo &CodeGenTypes::getFunctionInfo(const ObjCMethodDecl *MD) {
184  llvm::SmallVector<CanQualType, 16> ArgTys;
185  ArgTys.push_back(Context.getCanonicalParamType(MD->getSelfDecl()->getType()));
186  ArgTys.push_back(Context.getCanonicalParamType(Context.getObjCSelType()));
187  // FIXME: Kill copy?
188  for (ObjCMethodDecl::param_iterator i = MD->param_begin(),
189         e = MD->param_end(); i != e; ++i) {
190    ArgTys.push_back(Context.getCanonicalParamType((*i)->getType()));
191  }
192  return getFunctionInfo(GetReturnType(MD->getResultType()),
193                         ArgTys,
194                         FunctionType::ExtInfo(
195                             /*NoReturn*/ false,
196                             /*HasRegParm*/ false,
197                             /*RegParm*/ 0,
198                             getCallingConventionForDecl(MD)));
199}
200
201const CGFunctionInfo &CodeGenTypes::getFunctionInfo(GlobalDecl GD) {
202  // FIXME: Do we need to handle ObjCMethodDecl?
203  const FunctionDecl *FD = cast<FunctionDecl>(GD.getDecl());
204
205  if (const CXXConstructorDecl *CD = dyn_cast<CXXConstructorDecl>(FD))
206    return getFunctionInfo(CD, GD.getCtorType());
207
208  if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(FD))
209    return getFunctionInfo(DD, GD.getDtorType());
210
211  return getFunctionInfo(FD);
212}
213
214const CGFunctionInfo &CodeGenTypes::getFunctionInfo(QualType ResTy,
215                                                    const CallArgList &Args,
216                                            const FunctionType::ExtInfo &Info) {
217  // FIXME: Kill copy.
218  llvm::SmallVector<CanQualType, 16> ArgTys;
219  for (CallArgList::const_iterator i = Args.begin(), e = Args.end();
220       i != e; ++i)
221    ArgTys.push_back(Context.getCanonicalParamType(i->Ty));
222  return getFunctionInfo(GetReturnType(ResTy), ArgTys, Info);
223}
224
225const CGFunctionInfo &CodeGenTypes::getFunctionInfo(QualType ResTy,
226                                                    const FunctionArgList &Args,
227                                            const FunctionType::ExtInfo &Info) {
228  // FIXME: Kill copy.
229  llvm::SmallVector<CanQualType, 16> ArgTys;
230  for (FunctionArgList::const_iterator i = Args.begin(), e = Args.end();
231       i != e; ++i)
232    ArgTys.push_back(Context.getCanonicalParamType((*i)->getType()));
233  return getFunctionInfo(GetReturnType(ResTy), ArgTys, Info);
234}
235
236const CGFunctionInfo &CodeGenTypes::getNullaryFunctionInfo() {
237  llvm::SmallVector<CanQualType, 1> args;
238  return getFunctionInfo(getContext().VoidTy, args, FunctionType::ExtInfo());
239}
240
241const CGFunctionInfo &CodeGenTypes::getFunctionInfo(CanQualType ResTy,
242                           const llvm::SmallVectorImpl<CanQualType> &ArgTys,
243                                            const FunctionType::ExtInfo &Info,
244                                                    bool IsRecursive) {
245#ifndef NDEBUG
246  for (llvm::SmallVectorImpl<CanQualType>::const_iterator
247         I = ArgTys.begin(), E = ArgTys.end(); I != E; ++I)
248    assert(I->isCanonicalAsParam());
249#endif
250
251  unsigned CC = ClangCallConvToLLVMCallConv(Info.getCC());
252
253  // Lookup or create unique function info.
254  llvm::FoldingSetNodeID ID;
255  CGFunctionInfo::Profile(ID, Info, ResTy,
256                          ArgTys.begin(), ArgTys.end());
257
258  void *InsertPos = 0;
259  CGFunctionInfo *FI = FunctionInfos.FindNodeOrInsertPos(ID, InsertPos);
260  if (FI)
261    return *FI;
262
263  // Construct the function info.
264  FI = new CGFunctionInfo(CC, Info.getNoReturn(), Info.getHasRegParm(), Info.getRegParm(), ResTy,
265                          ArgTys.data(), ArgTys.size());
266  FunctionInfos.InsertNode(FI, InsertPos);
267
268  // Compute ABI information.
269  getABIInfo().computeInfo(*FI);
270
271  // Loop over all of the computed argument and return value info.  If any of
272  // them are direct or extend without a specified coerce type, specify the
273  // default now.
274  ABIArgInfo &RetInfo = FI->getReturnInfo();
275  if (RetInfo.canHaveCoerceToType() && RetInfo.getCoerceToType() == 0)
276    RetInfo.setCoerceToType(ConvertTypeRecursive(FI->getReturnType()));
277
278  for (CGFunctionInfo::arg_iterator I = FI->arg_begin(), E = FI->arg_end();
279       I != E; ++I)
280    if (I->info.canHaveCoerceToType() && I->info.getCoerceToType() == 0)
281      I->info.setCoerceToType(ConvertTypeRecursive(I->type));
282
283  // If this is a top-level call and ConvertTypeRecursive hit unresolved pointer
284  // types, resolve them now.  These pointers may point to this function, which
285  // we *just* filled in the FunctionInfo for.
286  if (!IsRecursive && !PointersToResolve.empty())
287    HandleLateResolvedPointers();
288
289  return *FI;
290}
291
292CGFunctionInfo::CGFunctionInfo(unsigned _CallingConvention,
293                               bool _NoReturn, bool _HasRegParm, unsigned _RegParm,
294                               CanQualType ResTy,
295                               const CanQualType *ArgTys,
296                               unsigned NumArgTys)
297  : CallingConvention(_CallingConvention),
298    EffectiveCallingConvention(_CallingConvention),
299    NoReturn(_NoReturn), HasRegParm(_HasRegParm), RegParm(_RegParm)
300{
301  NumArgs = NumArgTys;
302
303  // FIXME: Coallocate with the CGFunctionInfo object.
304  Args = new ArgInfo[1 + NumArgTys];
305  Args[0].type = ResTy;
306  for (unsigned i = 0; i != NumArgTys; ++i)
307    Args[1 + i].type = ArgTys[i];
308}
309
310/***/
311
312void CodeGenTypes::GetExpandedTypes(QualType Ty,
313                                    std::vector<const llvm::Type*> &ArgTys,
314                                    bool IsRecursive) {
315  const RecordType *RT = Ty->getAsStructureType();
316  assert(RT && "Can only expand structure types.");
317  const RecordDecl *RD = RT->getDecl();
318  assert(!RD->hasFlexibleArrayMember() &&
319         "Cannot expand structure with flexible array.");
320
321  for (RecordDecl::field_iterator i = RD->field_begin(), e = RD->field_end();
322         i != e; ++i) {
323    const FieldDecl *FD = *i;
324    assert(!FD->isBitField() &&
325           "Cannot expand structure with bit-field members.");
326
327    QualType FT = FD->getType();
328    if (CodeGenFunction::hasAggregateLLVMType(FT))
329      GetExpandedTypes(FT, ArgTys, IsRecursive);
330    else
331      ArgTys.push_back(ConvertType(FT, IsRecursive));
332  }
333}
334
335llvm::Function::arg_iterator
336CodeGenFunction::ExpandTypeFromArgs(QualType Ty, LValue LV,
337                                    llvm::Function::arg_iterator AI) {
338  const RecordType *RT = Ty->getAsStructureType();
339  assert(RT && "Can only expand structure types.");
340
341  RecordDecl *RD = RT->getDecl();
342  assert(LV.isSimple() &&
343         "Unexpected non-simple lvalue during struct expansion.");
344  llvm::Value *Addr = LV.getAddress();
345  for (RecordDecl::field_iterator i = RD->field_begin(), e = RD->field_end();
346         i != e; ++i) {
347    FieldDecl *FD = *i;
348    QualType FT = FD->getType();
349
350    // FIXME: What are the right qualifiers here?
351    LValue LV = EmitLValueForField(Addr, FD, 0);
352    if (CodeGenFunction::hasAggregateLLVMType(FT)) {
353      AI = ExpandTypeFromArgs(FT, LV, AI);
354    } else {
355      EmitStoreThroughLValue(RValue::get(AI), LV, FT);
356      ++AI;
357    }
358  }
359
360  return AI;
361}
362
363void
364CodeGenFunction::ExpandTypeToArgs(QualType Ty, RValue RV,
365                                  llvm::SmallVector<llvm::Value*, 16> &Args) {
366  const RecordType *RT = Ty->getAsStructureType();
367  assert(RT && "Can only expand structure types.");
368
369  RecordDecl *RD = RT->getDecl();
370  assert(RV.isAggregate() && "Unexpected rvalue during struct expansion");
371  llvm::Value *Addr = RV.getAggregateAddr();
372  for (RecordDecl::field_iterator i = RD->field_begin(), e = RD->field_end();
373         i != e; ++i) {
374    FieldDecl *FD = *i;
375    QualType FT = FD->getType();
376
377    // FIXME: What are the right qualifiers here?
378    LValue LV = EmitLValueForField(Addr, FD, 0);
379    if (CodeGenFunction::hasAggregateLLVMType(FT)) {
380      ExpandTypeToArgs(FT, RValue::getAggregate(LV.getAddress()), Args);
381    } else {
382      RValue RV = EmitLoadOfLValue(LV, FT);
383      assert(RV.isScalar() &&
384             "Unexpected non-scalar rvalue during struct expansion.");
385      Args.push_back(RV.getScalarVal());
386    }
387  }
388}
389
390/// EnterStructPointerForCoercedAccess - Given a struct pointer that we are
391/// accessing some number of bytes out of it, try to gep into the struct to get
392/// at its inner goodness.  Dive as deep as possible without entering an element
393/// with an in-memory size smaller than DstSize.
394static llvm::Value *
395EnterStructPointerForCoercedAccess(llvm::Value *SrcPtr,
396                                   const llvm::StructType *SrcSTy,
397                                   uint64_t DstSize, CodeGenFunction &CGF) {
398  // We can't dive into a zero-element struct.
399  if (SrcSTy->getNumElements() == 0) return SrcPtr;
400
401  const llvm::Type *FirstElt = SrcSTy->getElementType(0);
402
403  // If the first elt is at least as large as what we're looking for, or if the
404  // first element is the same size as the whole struct, we can enter it.
405  uint64_t FirstEltSize =
406    CGF.CGM.getTargetData().getTypeAllocSize(FirstElt);
407  if (FirstEltSize < DstSize &&
408      FirstEltSize < CGF.CGM.getTargetData().getTypeAllocSize(SrcSTy))
409    return SrcPtr;
410
411  // GEP into the first element.
412  SrcPtr = CGF.Builder.CreateConstGEP2_32(SrcPtr, 0, 0, "coerce.dive");
413
414  // If the first element is a struct, recurse.
415  const llvm::Type *SrcTy =
416    cast<llvm::PointerType>(SrcPtr->getType())->getElementType();
417  if (const llvm::StructType *SrcSTy = dyn_cast<llvm::StructType>(SrcTy))
418    return EnterStructPointerForCoercedAccess(SrcPtr, SrcSTy, DstSize, CGF);
419
420  return SrcPtr;
421}
422
423/// CoerceIntOrPtrToIntOrPtr - Convert a value Val to the specific Ty where both
424/// are either integers or pointers.  This does a truncation of the value if it
425/// is too large or a zero extension if it is too small.
426static llvm::Value *CoerceIntOrPtrToIntOrPtr(llvm::Value *Val,
427                                             const llvm::Type *Ty,
428                                             CodeGenFunction &CGF) {
429  if (Val->getType() == Ty)
430    return Val;
431
432  if (isa<llvm::PointerType>(Val->getType())) {
433    // If this is Pointer->Pointer avoid conversion to and from int.
434    if (isa<llvm::PointerType>(Ty))
435      return CGF.Builder.CreateBitCast(Val, Ty, "coerce.val");
436
437    // Convert the pointer to an integer so we can play with its width.
438    Val = CGF.Builder.CreatePtrToInt(Val, CGF.IntPtrTy, "coerce.val.pi");
439  }
440
441  const llvm::Type *DestIntTy = Ty;
442  if (isa<llvm::PointerType>(DestIntTy))
443    DestIntTy = CGF.IntPtrTy;
444
445  if (Val->getType() != DestIntTy)
446    Val = CGF.Builder.CreateIntCast(Val, DestIntTy, false, "coerce.val.ii");
447
448  if (isa<llvm::PointerType>(Ty))
449    Val = CGF.Builder.CreateIntToPtr(Val, Ty, "coerce.val.ip");
450  return Val;
451}
452
453
454
455/// CreateCoercedLoad - Create a load from \arg SrcPtr interpreted as
456/// a pointer to an object of type \arg Ty.
457///
458/// This safely handles the case when the src type is smaller than the
459/// destination type; in this situation the values of bits which not
460/// present in the src are undefined.
461static llvm::Value *CreateCoercedLoad(llvm::Value *SrcPtr,
462                                      const llvm::Type *Ty,
463                                      CodeGenFunction &CGF) {
464  const llvm::Type *SrcTy =
465    cast<llvm::PointerType>(SrcPtr->getType())->getElementType();
466
467  // If SrcTy and Ty are the same, just do a load.
468  if (SrcTy == Ty)
469    return CGF.Builder.CreateLoad(SrcPtr);
470
471  uint64_t DstSize = CGF.CGM.getTargetData().getTypeAllocSize(Ty);
472
473  if (const llvm::StructType *SrcSTy = dyn_cast<llvm::StructType>(SrcTy)) {
474    SrcPtr = EnterStructPointerForCoercedAccess(SrcPtr, SrcSTy, DstSize, CGF);
475    SrcTy = cast<llvm::PointerType>(SrcPtr->getType())->getElementType();
476  }
477
478  uint64_t SrcSize = CGF.CGM.getTargetData().getTypeAllocSize(SrcTy);
479
480  // If the source and destination are integer or pointer types, just do an
481  // extension or truncation to the desired type.
482  if ((isa<llvm::IntegerType>(Ty) || isa<llvm::PointerType>(Ty)) &&
483      (isa<llvm::IntegerType>(SrcTy) || isa<llvm::PointerType>(SrcTy))) {
484    llvm::LoadInst *Load = CGF.Builder.CreateLoad(SrcPtr);
485    return CoerceIntOrPtrToIntOrPtr(Load, Ty, CGF);
486  }
487
488  // If load is legal, just bitcast the src pointer.
489  if (SrcSize >= DstSize) {
490    // Generally SrcSize is never greater than DstSize, since this means we are
491    // losing bits. However, this can happen in cases where the structure has
492    // additional padding, for example due to a user specified alignment.
493    //
494    // FIXME: Assert that we aren't truncating non-padding bits when have access
495    // to that information.
496    llvm::Value *Casted =
497      CGF.Builder.CreateBitCast(SrcPtr, llvm::PointerType::getUnqual(Ty));
498    llvm::LoadInst *Load = CGF.Builder.CreateLoad(Casted);
499    // FIXME: Use better alignment / avoid requiring aligned load.
500    Load->setAlignment(1);
501    return Load;
502  }
503
504  // Otherwise do coercion through memory. This is stupid, but
505  // simple.
506  llvm::Value *Tmp = CGF.CreateTempAlloca(Ty);
507  llvm::Value *Casted =
508    CGF.Builder.CreateBitCast(Tmp, llvm::PointerType::getUnqual(SrcTy));
509  llvm::StoreInst *Store =
510    CGF.Builder.CreateStore(CGF.Builder.CreateLoad(SrcPtr), Casted);
511  // FIXME: Use better alignment / avoid requiring aligned store.
512  Store->setAlignment(1);
513  return CGF.Builder.CreateLoad(Tmp);
514}
515
516/// CreateCoercedStore - Create a store to \arg DstPtr from \arg Src,
517/// where the source and destination may have different types.
518///
519/// This safely handles the case when the src type is larger than the
520/// destination type; the upper bits of the src will be lost.
521static void CreateCoercedStore(llvm::Value *Src,
522                               llvm::Value *DstPtr,
523                               bool DstIsVolatile,
524                               CodeGenFunction &CGF) {
525  const llvm::Type *SrcTy = Src->getType();
526  const llvm::Type *DstTy =
527    cast<llvm::PointerType>(DstPtr->getType())->getElementType();
528  if (SrcTy == DstTy) {
529    CGF.Builder.CreateStore(Src, DstPtr, DstIsVolatile);
530    return;
531  }
532
533  uint64_t SrcSize = CGF.CGM.getTargetData().getTypeAllocSize(SrcTy);
534
535  if (const llvm::StructType *DstSTy = dyn_cast<llvm::StructType>(DstTy)) {
536    DstPtr = EnterStructPointerForCoercedAccess(DstPtr, DstSTy, SrcSize, CGF);
537    DstTy = cast<llvm::PointerType>(DstPtr->getType())->getElementType();
538  }
539
540  // If the source and destination are integer or pointer types, just do an
541  // extension or truncation to the desired type.
542  if ((isa<llvm::IntegerType>(SrcTy) || isa<llvm::PointerType>(SrcTy)) &&
543      (isa<llvm::IntegerType>(DstTy) || isa<llvm::PointerType>(DstTy))) {
544    Src = CoerceIntOrPtrToIntOrPtr(Src, DstTy, CGF);
545    CGF.Builder.CreateStore(Src, DstPtr, DstIsVolatile);
546    return;
547  }
548
549  uint64_t DstSize = CGF.CGM.getTargetData().getTypeAllocSize(DstTy);
550
551  // If store is legal, just bitcast the src pointer.
552  if (SrcSize <= DstSize) {
553    llvm::Value *Casted =
554      CGF.Builder.CreateBitCast(DstPtr, llvm::PointerType::getUnqual(SrcTy));
555    // FIXME: Use better alignment / avoid requiring aligned store.
556    CGF.Builder.CreateStore(Src, Casted, DstIsVolatile)->setAlignment(1);
557  } else {
558    // Otherwise do coercion through memory. This is stupid, but
559    // simple.
560
561    // Generally SrcSize is never greater than DstSize, since this means we are
562    // losing bits. However, this can happen in cases where the structure has
563    // additional padding, for example due to a user specified alignment.
564    //
565    // FIXME: Assert that we aren't truncating non-padding bits when have access
566    // to that information.
567    llvm::Value *Tmp = CGF.CreateTempAlloca(SrcTy);
568    CGF.Builder.CreateStore(Src, Tmp);
569    llvm::Value *Casted =
570      CGF.Builder.CreateBitCast(Tmp, llvm::PointerType::getUnqual(DstTy));
571    llvm::LoadInst *Load = CGF.Builder.CreateLoad(Casted);
572    // FIXME: Use better alignment / avoid requiring aligned load.
573    Load->setAlignment(1);
574    CGF.Builder.CreateStore(Load, DstPtr, DstIsVolatile);
575  }
576}
577
578/***/
579
580bool CodeGenModule::ReturnTypeUsesSRet(const CGFunctionInfo &FI) {
581  return FI.getReturnInfo().isIndirect();
582}
583
584bool CodeGenModule::ReturnTypeUsesFPRet(QualType ResultType) {
585  if (const BuiltinType *BT = ResultType->getAs<BuiltinType>()) {
586    switch (BT->getKind()) {
587    default:
588      return false;
589    case BuiltinType::Float:
590      return getContext().Target.useObjCFPRetForRealType(TargetInfo::Float);
591    case BuiltinType::Double:
592      return getContext().Target.useObjCFPRetForRealType(TargetInfo::Double);
593    case BuiltinType::LongDouble:
594      return getContext().Target.useObjCFPRetForRealType(
595        TargetInfo::LongDouble);
596    }
597  }
598
599  return false;
600}
601
602const llvm::FunctionType *CodeGenTypes::GetFunctionType(GlobalDecl GD) {
603  const CGFunctionInfo &FI = getFunctionInfo(GD);
604
605  // For definition purposes, don't consider a K&R function variadic.
606  bool Variadic = false;
607  if (const FunctionProtoType *FPT =
608        cast<FunctionDecl>(GD.getDecl())->getType()->getAs<FunctionProtoType>())
609    Variadic = FPT->isVariadic();
610
611  return GetFunctionType(FI, Variadic, false);
612}
613
614const llvm::FunctionType *
615CodeGenTypes::GetFunctionType(const CGFunctionInfo &FI, bool IsVariadic,
616                              bool IsRecursive) {
617  std::vector<const llvm::Type*> ArgTys;
618
619  const llvm::Type *ResultType = 0;
620
621  QualType RetTy = FI.getReturnType();
622  const ABIArgInfo &RetAI = FI.getReturnInfo();
623  switch (RetAI.getKind()) {
624  case ABIArgInfo::Expand:
625    assert(0 && "Invalid ABI kind for return argument");
626
627  case ABIArgInfo::Extend:
628  case ABIArgInfo::Direct:
629    ResultType = RetAI.getCoerceToType();
630    break;
631
632  case ABIArgInfo::Indirect: {
633    assert(!RetAI.getIndirectAlign() && "Align unused on indirect return.");
634    ResultType = llvm::Type::getVoidTy(getLLVMContext());
635    const llvm::Type *STy = ConvertType(RetTy, IsRecursive);
636    unsigned AS = Context.getTargetAddressSpace(RetTy);
637    ArgTys.push_back(llvm::PointerType::get(STy, AS));
638    break;
639  }
640
641  case ABIArgInfo::Ignore:
642    ResultType = llvm::Type::getVoidTy(getLLVMContext());
643    break;
644  }
645
646  for (CGFunctionInfo::const_arg_iterator it = FI.arg_begin(),
647         ie = FI.arg_end(); it != ie; ++it) {
648    const ABIArgInfo &AI = it->info;
649
650    switch (AI.getKind()) {
651    case ABIArgInfo::Ignore:
652      break;
653
654    case ABIArgInfo::Indirect: {
655      // indirect arguments are always on the stack, which is addr space #0.
656      const llvm::Type *LTy = ConvertTypeForMem(it->type, IsRecursive);
657      ArgTys.push_back(llvm::PointerType::getUnqual(LTy));
658      break;
659    }
660
661    case ABIArgInfo::Extend:
662    case ABIArgInfo::Direct: {
663      // If the coerce-to type is a first class aggregate, flatten it.  Either
664      // way is semantically identical, but fast-isel and the optimizer
665      // generally likes scalar values better than FCAs.
666      const llvm::Type *ArgTy = AI.getCoerceToType();
667      if (const llvm::StructType *STy = dyn_cast<llvm::StructType>(ArgTy)) {
668        for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i)
669          ArgTys.push_back(STy->getElementType(i));
670      } else {
671        ArgTys.push_back(ArgTy);
672      }
673      break;
674    }
675
676    case ABIArgInfo::Expand:
677      GetExpandedTypes(it->type, ArgTys, IsRecursive);
678      break;
679    }
680  }
681
682  return llvm::FunctionType::get(ResultType, ArgTys, IsVariadic);
683}
684
685const llvm::Type *CodeGenTypes::GetFunctionTypeForVTable(GlobalDecl GD) {
686  const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());
687  const FunctionProtoType *FPT = MD->getType()->getAs<FunctionProtoType>();
688
689  if (!VerifyFuncTypeComplete(FPT)) {
690    const CGFunctionInfo *Info;
691    if (isa<CXXDestructorDecl>(MD))
692      Info = &getFunctionInfo(cast<CXXDestructorDecl>(MD), GD.getDtorType());
693    else
694      Info = &getFunctionInfo(MD);
695    return GetFunctionType(*Info, FPT->isVariadic(), false);
696  }
697
698  return llvm::OpaqueType::get(getLLVMContext());
699}
700
701void CodeGenModule::ConstructAttributeList(const CGFunctionInfo &FI,
702                                           const Decl *TargetDecl,
703                                           AttributeListType &PAL,
704                                           unsigned &CallingConv) {
705  unsigned FuncAttrs = 0;
706  unsigned RetAttrs = 0;
707
708  CallingConv = FI.getEffectiveCallingConvention();
709
710  if (FI.isNoReturn())
711    FuncAttrs |= llvm::Attribute::NoReturn;
712
713  // FIXME: handle sseregparm someday...
714  if (TargetDecl) {
715    if (TargetDecl->hasAttr<NoThrowAttr>())
716      FuncAttrs |= llvm::Attribute::NoUnwind;
717    else if (const FunctionDecl *Fn = dyn_cast<FunctionDecl>(TargetDecl)) {
718      const FunctionProtoType *FPT = Fn->getType()->getAs<FunctionProtoType>();
719      if (FPT && FPT->isNothrow(getContext()))
720        FuncAttrs |= llvm::Attribute::NoUnwind;
721    }
722
723    if (TargetDecl->hasAttr<NoReturnAttr>())
724      FuncAttrs |= llvm::Attribute::NoReturn;
725    if (TargetDecl->hasAttr<ConstAttr>())
726      FuncAttrs |= llvm::Attribute::ReadNone;
727    else if (TargetDecl->hasAttr<PureAttr>())
728      FuncAttrs |= llvm::Attribute::ReadOnly;
729    if (TargetDecl->hasAttr<MallocAttr>())
730      RetAttrs |= llvm::Attribute::NoAlias;
731  }
732
733  if (CodeGenOpts.OptimizeSize)
734    FuncAttrs |= llvm::Attribute::OptimizeForSize;
735  if (CodeGenOpts.DisableRedZone)
736    FuncAttrs |= llvm::Attribute::NoRedZone;
737  if (CodeGenOpts.NoImplicitFloat)
738    FuncAttrs |= llvm::Attribute::NoImplicitFloat;
739
740  QualType RetTy = FI.getReturnType();
741  unsigned Index = 1;
742  const ABIArgInfo &RetAI = FI.getReturnInfo();
743  switch (RetAI.getKind()) {
744  case ABIArgInfo::Extend:
745   if (RetTy->hasSignedIntegerRepresentation())
746     RetAttrs |= llvm::Attribute::SExt;
747   else if (RetTy->hasUnsignedIntegerRepresentation())
748     RetAttrs |= llvm::Attribute::ZExt;
749    break;
750  case ABIArgInfo::Direct:
751  case ABIArgInfo::Ignore:
752    break;
753
754  case ABIArgInfo::Indirect:
755    PAL.push_back(llvm::AttributeWithIndex::get(Index,
756                                                llvm::Attribute::StructRet));
757    ++Index;
758    // sret disables readnone and readonly
759    FuncAttrs &= ~(llvm::Attribute::ReadOnly |
760                   llvm::Attribute::ReadNone);
761    break;
762
763  case ABIArgInfo::Expand:
764    assert(0 && "Invalid ABI kind for return argument");
765  }
766
767  if (RetAttrs)
768    PAL.push_back(llvm::AttributeWithIndex::get(0, RetAttrs));
769
770  // FIXME: RegParm should be reduced in case of global register variable.
771  signed RegParm;
772  if (FI.getHasRegParm())
773    RegParm = FI.getRegParm();
774  else
775    RegParm = CodeGenOpts.NumRegisterParameters;
776
777  unsigned PointerWidth = getContext().Target.getPointerWidth(0);
778  for (CGFunctionInfo::const_arg_iterator it = FI.arg_begin(),
779         ie = FI.arg_end(); it != ie; ++it) {
780    QualType ParamType = it->type;
781    const ABIArgInfo &AI = it->info;
782    unsigned Attributes = 0;
783
784    // 'restrict' -> 'noalias' is done in EmitFunctionProlog when we
785    // have the corresponding parameter variable.  It doesn't make
786    // sense to do it here because parameters are so messed up.
787    switch (AI.getKind()) {
788    case ABIArgInfo::Extend:
789      if (ParamType->isSignedIntegerType())
790        Attributes |= llvm::Attribute::SExt;
791      else if (ParamType->isUnsignedIntegerType())
792        Attributes |= llvm::Attribute::ZExt;
793      // FALL THROUGH
794    case ABIArgInfo::Direct:
795      if (RegParm > 0 &&
796          (ParamType->isIntegerType() || ParamType->isPointerType())) {
797        RegParm -=
798        (Context.getTypeSize(ParamType) + PointerWidth - 1) / PointerWidth;
799        if (RegParm >= 0)
800          Attributes |= llvm::Attribute::InReg;
801      }
802      // FIXME: handle sseregparm someday...
803
804      if (const llvm::StructType *STy =
805            dyn_cast<llvm::StructType>(AI.getCoerceToType()))
806        Index += STy->getNumElements()-1;  // 1 will be added below.
807      break;
808
809    case ABIArgInfo::Indirect:
810      if (AI.getIndirectByVal())
811        Attributes |= llvm::Attribute::ByVal;
812
813      Attributes |=
814        llvm::Attribute::constructAlignmentFromInt(AI.getIndirectAlign());
815      // byval disables readnone and readonly.
816      FuncAttrs &= ~(llvm::Attribute::ReadOnly |
817                     llvm::Attribute::ReadNone);
818      break;
819
820    case ABIArgInfo::Ignore:
821      // Skip increment, no matching LLVM parameter.
822      continue;
823
824    case ABIArgInfo::Expand: {
825      std::vector<const llvm::Type*> Tys;
826      // FIXME: This is rather inefficient. Do we ever actually need to do
827      // anything here? The result should be just reconstructed on the other
828      // side, so extension should be a non-issue.
829      getTypes().GetExpandedTypes(ParamType, Tys, false);
830      Index += Tys.size();
831      continue;
832    }
833    }
834
835    if (Attributes)
836      PAL.push_back(llvm::AttributeWithIndex::get(Index, Attributes));
837    ++Index;
838  }
839  if (FuncAttrs)
840    PAL.push_back(llvm::AttributeWithIndex::get(~0, FuncAttrs));
841}
842
843/// An argument came in as a promoted argument; demote it back to its
844/// declared type.
845static llvm::Value *emitArgumentDemotion(CodeGenFunction &CGF,
846                                         const VarDecl *var,
847                                         llvm::Value *value) {
848  const llvm::Type *varType = CGF.ConvertType(var->getType());
849
850  // This can happen with promotions that actually don't change the
851  // underlying type, like the enum promotions.
852  if (value->getType() == varType) return value;
853
854  assert((varType->isIntegerTy() || varType->isFloatingPointTy())
855         && "unexpected promotion type");
856
857  if (isa<llvm::IntegerType>(varType))
858    return CGF.Builder.CreateTrunc(value, varType, "arg.unpromote");
859
860  return CGF.Builder.CreateFPCast(value, varType, "arg.unpromote");
861}
862
863void CodeGenFunction::EmitFunctionProlog(const CGFunctionInfo &FI,
864                                         llvm::Function *Fn,
865                                         const FunctionArgList &Args) {
866  // If this is an implicit-return-zero function, go ahead and
867  // initialize the return value.  TODO: it might be nice to have
868  // a more general mechanism for this that didn't require synthesized
869  // return statements.
870  if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(CurFuncDecl)) {
871    if (FD->hasImplicitReturnZero()) {
872      QualType RetTy = FD->getResultType().getUnqualifiedType();
873      const llvm::Type* LLVMTy = CGM.getTypes().ConvertType(RetTy);
874      llvm::Constant* Zero = llvm::Constant::getNullValue(LLVMTy);
875      Builder.CreateStore(Zero, ReturnValue);
876    }
877  }
878
879  // FIXME: We no longer need the types from FunctionArgList; lift up and
880  // simplify.
881
882  // Emit allocs for param decls.  Give the LLVM Argument nodes names.
883  llvm::Function::arg_iterator AI = Fn->arg_begin();
884
885  // Name the struct return argument.
886  if (CGM.ReturnTypeUsesSRet(FI)) {
887    AI->setName("agg.result");
888    ++AI;
889  }
890
891  assert(FI.arg_size() == Args.size() &&
892         "Mismatch between function signature & arguments.");
893  unsigned ArgNo = 1;
894  CGFunctionInfo::const_arg_iterator info_it = FI.arg_begin();
895  for (FunctionArgList::const_iterator i = Args.begin(), e = Args.end();
896       i != e; ++i, ++info_it, ++ArgNo) {
897    const VarDecl *Arg = *i;
898    QualType Ty = info_it->type;
899    const ABIArgInfo &ArgI = info_it->info;
900
901    bool isPromoted =
902      isa<ParmVarDecl>(Arg) && cast<ParmVarDecl>(Arg)->isKNRPromoted();
903
904    switch (ArgI.getKind()) {
905    case ABIArgInfo::Indirect: {
906      llvm::Value *V = AI;
907
908      if (hasAggregateLLVMType(Ty)) {
909        // Aggregates and complex variables are accessed by reference.  All we
910        // need to do is realign the value, if requested
911        if (ArgI.getIndirectRealign()) {
912          llvm::Value *AlignedTemp = CreateMemTemp(Ty, "coerce");
913
914          // Copy from the incoming argument pointer to the temporary with the
915          // appropriate alignment.
916          //
917          // FIXME: We should have a common utility for generating an aggregate
918          // copy.
919          const llvm::Type *I8PtrTy = Builder.getInt8PtrTy();
920          CharUnits Size = getContext().getTypeSizeInChars(Ty);
921          llvm::Value *Dst = Builder.CreateBitCast(AlignedTemp, I8PtrTy);
922          llvm::Value *Src = Builder.CreateBitCast(V, I8PtrTy);
923          Builder.CreateMemCpy(Dst,
924                               Src,
925                               llvm::ConstantInt::get(IntPtrTy,
926                                                      Size.getQuantity()),
927                               ArgI.getIndirectAlign(),
928                               false);
929          V = AlignedTemp;
930        }
931      } else {
932        // Load scalar value from indirect argument.
933        CharUnits Alignment = getContext().getTypeAlignInChars(Ty);
934        V = EmitLoadOfScalar(V, false, Alignment.getQuantity(), Ty);
935
936        if (isPromoted)
937          V = emitArgumentDemotion(*this, Arg, V);
938      }
939      EmitParmDecl(*Arg, V, ArgNo);
940      break;
941    }
942
943    case ABIArgInfo::Extend:
944    case ABIArgInfo::Direct: {
945      // If we have the trivial case, handle it with no muss and fuss.
946      if (!isa<llvm::StructType>(ArgI.getCoerceToType()) &&
947          ArgI.getCoerceToType() == ConvertType(Ty) &&
948          ArgI.getDirectOffset() == 0) {
949        assert(AI != Fn->arg_end() && "Argument mismatch!");
950        llvm::Value *V = AI;
951
952        if (Arg->getType().isRestrictQualified())
953          AI->addAttr(llvm::Attribute::NoAlias);
954
955        if (isPromoted)
956          V = emitArgumentDemotion(*this, Arg, V);
957
958        EmitParmDecl(*Arg, V, ArgNo);
959        break;
960      }
961
962      llvm::AllocaInst *Alloca = CreateMemTemp(Ty, "coerce");
963
964      // The alignment we need to use is the max of the requested alignment for
965      // the argument plus the alignment required by our access code below.
966      unsigned AlignmentToUse =
967        CGM.getTargetData().getABITypeAlignment(ArgI.getCoerceToType());
968      AlignmentToUse = std::max(AlignmentToUse,
969                        (unsigned)getContext().getDeclAlign(Arg).getQuantity());
970
971      Alloca->setAlignment(AlignmentToUse);
972      llvm::Value *V = Alloca;
973      llvm::Value *Ptr = V;    // Pointer to store into.
974
975      // If the value is offset in memory, apply the offset now.
976      if (unsigned Offs = ArgI.getDirectOffset()) {
977        Ptr = Builder.CreateBitCast(Ptr, Builder.getInt8PtrTy());
978        Ptr = Builder.CreateConstGEP1_32(Ptr, Offs);
979        Ptr = Builder.CreateBitCast(Ptr,
980                          llvm::PointerType::getUnqual(ArgI.getCoerceToType()));
981      }
982
983      // If the coerce-to type is a first class aggregate, we flatten it and
984      // pass the elements. Either way is semantically identical, but fast-isel
985      // and the optimizer generally likes scalar values better than FCAs.
986      if (const llvm::StructType *STy =
987            dyn_cast<llvm::StructType>(ArgI.getCoerceToType())) {
988        Ptr = Builder.CreateBitCast(Ptr, llvm::PointerType::getUnqual(STy));
989
990        for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
991          assert(AI != Fn->arg_end() && "Argument mismatch!");
992          AI->setName(Arg->getName() + ".coerce" + llvm::Twine(i));
993          llvm::Value *EltPtr = Builder.CreateConstGEP2_32(Ptr, 0, i);
994          Builder.CreateStore(AI++, EltPtr);
995        }
996      } else {
997        // Simple case, just do a coerced store of the argument into the alloca.
998        assert(AI != Fn->arg_end() && "Argument mismatch!");
999        AI->setName(Arg->getName() + ".coerce");
1000        CreateCoercedStore(AI++, Ptr, /*DestIsVolatile=*/false, *this);
1001      }
1002
1003
1004      // Match to what EmitParmDecl is expecting for this type.
1005      if (!CodeGenFunction::hasAggregateLLVMType(Ty)) {
1006        V = EmitLoadOfScalar(V, false, AlignmentToUse, Ty);
1007        if (isPromoted)
1008          V = emitArgumentDemotion(*this, Arg, V);
1009      }
1010      EmitParmDecl(*Arg, V, ArgNo);
1011      continue;  // Skip ++AI increment, already done.
1012    }
1013
1014    case ABIArgInfo::Expand: {
1015      // If this structure was expanded into multiple arguments then
1016      // we need to create a temporary and reconstruct it from the
1017      // arguments.
1018      llvm::Value *Temp = CreateMemTemp(Ty, Arg->getName() + ".addr");
1019      llvm::Function::arg_iterator End =
1020        ExpandTypeFromArgs(Ty, MakeAddrLValue(Temp, Ty), AI);
1021      EmitParmDecl(*Arg, Temp, ArgNo);
1022
1023      // Name the arguments used in expansion and increment AI.
1024      unsigned Index = 0;
1025      for (; AI != End; ++AI, ++Index)
1026        AI->setName(Arg->getName() + "." + llvm::Twine(Index));
1027      continue;
1028    }
1029
1030    case ABIArgInfo::Ignore:
1031      // Initialize the local variable appropriately.
1032      if (hasAggregateLLVMType(Ty))
1033        EmitParmDecl(*Arg, CreateMemTemp(Ty), ArgNo);
1034      else
1035        EmitParmDecl(*Arg, llvm::UndefValue::get(ConvertType(Arg->getType())),
1036                     ArgNo);
1037
1038      // Skip increment, no matching LLVM parameter.
1039      continue;
1040    }
1041
1042    ++AI;
1043  }
1044  assert(AI == Fn->arg_end() && "Argument mismatch!");
1045}
1046
1047void CodeGenFunction::EmitFunctionEpilog(const CGFunctionInfo &FI) {
1048  // Functions with no result always return void.
1049  if (ReturnValue == 0) {
1050    Builder.CreateRetVoid();
1051    return;
1052  }
1053
1054  llvm::DebugLoc RetDbgLoc;
1055  llvm::Value *RV = 0;
1056  QualType RetTy = FI.getReturnType();
1057  const ABIArgInfo &RetAI = FI.getReturnInfo();
1058
1059  switch (RetAI.getKind()) {
1060  case ABIArgInfo::Indirect: {
1061    unsigned Alignment = getContext().getTypeAlignInChars(RetTy).getQuantity();
1062    if (RetTy->isAnyComplexType()) {
1063      ComplexPairTy RT = LoadComplexFromAddr(ReturnValue, false);
1064      StoreComplexToAddr(RT, CurFn->arg_begin(), false);
1065    } else if (CodeGenFunction::hasAggregateLLVMType(RetTy)) {
1066      // Do nothing; aggregrates get evaluated directly into the destination.
1067    } else {
1068      EmitStoreOfScalar(Builder.CreateLoad(ReturnValue), CurFn->arg_begin(),
1069                        false, Alignment, RetTy);
1070    }
1071    break;
1072  }
1073
1074  case ABIArgInfo::Extend:
1075  case ABIArgInfo::Direct:
1076    if (RetAI.getCoerceToType() == ConvertType(RetTy) &&
1077        RetAI.getDirectOffset() == 0) {
1078      // The internal return value temp always will have pointer-to-return-type
1079      // type, just do a load.
1080
1081      // If the instruction right before the insertion point is a store to the
1082      // return value, we can elide the load, zap the store, and usually zap the
1083      // alloca.
1084      llvm::BasicBlock *InsertBB = Builder.GetInsertBlock();
1085      llvm::StoreInst *SI = 0;
1086      if (InsertBB->empty() ||
1087          !(SI = dyn_cast<llvm::StoreInst>(&InsertBB->back())) ||
1088          SI->getPointerOperand() != ReturnValue || SI->isVolatile()) {
1089        RV = Builder.CreateLoad(ReturnValue);
1090      } else {
1091        // Get the stored value and nuke the now-dead store.
1092        RetDbgLoc = SI->getDebugLoc();
1093        RV = SI->getValueOperand();
1094        SI->eraseFromParent();
1095
1096        // If that was the only use of the return value, nuke it as well now.
1097        if (ReturnValue->use_empty() && isa<llvm::AllocaInst>(ReturnValue)) {
1098          cast<llvm::AllocaInst>(ReturnValue)->eraseFromParent();
1099          ReturnValue = 0;
1100        }
1101      }
1102    } else {
1103      llvm::Value *V = ReturnValue;
1104      // If the value is offset in memory, apply the offset now.
1105      if (unsigned Offs = RetAI.getDirectOffset()) {
1106        V = Builder.CreateBitCast(V, Builder.getInt8PtrTy());
1107        V = Builder.CreateConstGEP1_32(V, Offs);
1108        V = Builder.CreateBitCast(V,
1109                         llvm::PointerType::getUnqual(RetAI.getCoerceToType()));
1110      }
1111
1112      RV = CreateCoercedLoad(V, RetAI.getCoerceToType(), *this);
1113    }
1114    break;
1115
1116  case ABIArgInfo::Ignore:
1117    break;
1118
1119  case ABIArgInfo::Expand:
1120    assert(0 && "Invalid ABI kind for return argument");
1121  }
1122
1123  llvm::Instruction *Ret = RV ? Builder.CreateRet(RV) : Builder.CreateRetVoid();
1124  if (!RetDbgLoc.isUnknown())
1125    Ret->setDebugLoc(RetDbgLoc);
1126}
1127
1128void CodeGenFunction::EmitDelegateCallArg(CallArgList &args,
1129                                          const VarDecl *param) {
1130  // StartFunction converted the ABI-lowered parameter(s) into a
1131  // local alloca.  We need to turn that into an r-value suitable
1132  // for EmitCall.
1133  llvm::Value *local = GetAddrOfLocalVar(param);
1134
1135  QualType type = param->getType();
1136
1137  // For the most part, we just need to load the alloca, except:
1138  // 1) aggregate r-values are actually pointers to temporaries, and
1139  // 2) references to aggregates are pointers directly to the aggregate.
1140  // I don't know why references to non-aggregates are different here.
1141  if (const ReferenceType *ref = type->getAs<ReferenceType>()) {
1142    if (hasAggregateLLVMType(ref->getPointeeType()))
1143      return args.add(RValue::getAggregate(local), type);
1144
1145    // Locals which are references to scalars are represented
1146    // with allocas holding the pointer.
1147    return args.add(RValue::get(Builder.CreateLoad(local)), type);
1148  }
1149
1150  if (type->isAnyComplexType()) {
1151    ComplexPairTy complex = LoadComplexFromAddr(local, /*volatile*/ false);
1152    return args.add(RValue::getComplex(complex), type);
1153  }
1154
1155  if (hasAggregateLLVMType(type))
1156    return args.add(RValue::getAggregate(local), type);
1157
1158  unsigned alignment = getContext().getDeclAlign(param).getQuantity();
1159  llvm::Value *value = EmitLoadOfScalar(local, false, alignment, type);
1160  return args.add(RValue::get(value), type);
1161}
1162
1163void CodeGenFunction::EmitCallArg(CallArgList &args, const Expr *E,
1164                                  QualType type) {
1165  if (type->isReferenceType())
1166    return args.add(EmitReferenceBindingToExpr(E, /*InitializedDecl=*/0),
1167                    type);
1168
1169  if (hasAggregateLLVMType(type) && isa<ImplicitCastExpr>(E) &&
1170      cast<CastExpr>(E)->getCastKind() == CK_LValueToRValue) {
1171    LValue L = EmitLValue(cast<CastExpr>(E)->getSubExpr());
1172    assert(L.isSimple());
1173    args.add(RValue::getAggregate(L.getAddress(), L.isVolatileQualified()),
1174             type, /*NeedsCopy*/true);
1175    return;
1176  }
1177
1178  args.add(EmitAnyExprToTemp(E), type);
1179}
1180
1181/// Emits a call or invoke instruction to the given function, depending
1182/// on the current state of the EH stack.
1183llvm::CallSite
1184CodeGenFunction::EmitCallOrInvoke(llvm::Value *Callee,
1185                                  llvm::Value * const *ArgBegin,
1186                                  llvm::Value * const *ArgEnd,
1187                                  const llvm::Twine &Name) {
1188  llvm::BasicBlock *InvokeDest = getInvokeDest();
1189  if (!InvokeDest)
1190    return Builder.CreateCall(Callee, ArgBegin, ArgEnd, Name);
1191
1192  llvm::BasicBlock *ContBB = createBasicBlock("invoke.cont");
1193  llvm::InvokeInst *Invoke = Builder.CreateInvoke(Callee, ContBB, InvokeDest,
1194                                                  ArgBegin, ArgEnd, Name);
1195  EmitBlock(ContBB);
1196  return Invoke;
1197}
1198
1199RValue CodeGenFunction::EmitCall(const CGFunctionInfo &CallInfo,
1200                                 llvm::Value *Callee,
1201                                 ReturnValueSlot ReturnValue,
1202                                 const CallArgList &CallArgs,
1203                                 const Decl *TargetDecl,
1204                                 llvm::Instruction **callOrInvoke) {
1205  // FIXME: We no longer need the types from CallArgs; lift up and simplify.
1206  llvm::SmallVector<llvm::Value*, 16> Args;
1207
1208  // Handle struct-return functions by passing a pointer to the
1209  // location that we would like to return into.
1210  QualType RetTy = CallInfo.getReturnType();
1211  const ABIArgInfo &RetAI = CallInfo.getReturnInfo();
1212
1213
1214  // If the call returns a temporary with struct return, create a temporary
1215  // alloca to hold the result, unless one is given to us.
1216  if (CGM.ReturnTypeUsesSRet(CallInfo)) {
1217    llvm::Value *Value = ReturnValue.getValue();
1218    if (!Value)
1219      Value = CreateMemTemp(RetTy);
1220    Args.push_back(Value);
1221  }
1222
1223  assert(CallInfo.arg_size() == CallArgs.size() &&
1224         "Mismatch between function signature & arguments.");
1225  CGFunctionInfo::const_arg_iterator info_it = CallInfo.arg_begin();
1226  for (CallArgList::const_iterator I = CallArgs.begin(), E = CallArgs.end();
1227       I != E; ++I, ++info_it) {
1228    const ABIArgInfo &ArgInfo = info_it->info;
1229    RValue RV = I->RV;
1230
1231    unsigned Alignment =
1232      getContext().getTypeAlignInChars(I->Ty).getQuantity();
1233    switch (ArgInfo.getKind()) {
1234    case ABIArgInfo::Indirect: {
1235      if (RV.isScalar() || RV.isComplex()) {
1236        // Make a temporary alloca to pass the argument.
1237        Args.push_back(CreateMemTemp(I->Ty));
1238        if (RV.isScalar())
1239          EmitStoreOfScalar(RV.getScalarVal(), Args.back(), false,
1240                            Alignment, I->Ty);
1241        else
1242          StoreComplexToAddr(RV.getComplexVal(), Args.back(), false);
1243      } else if (I->NeedsCopy && !ArgInfo.getIndirectByVal()) {
1244        Args.push_back(CreateMemTemp(I->Ty));
1245        EmitAggregateCopy(Args.back(), RV.getAggregateAddr(), I->Ty,
1246                          RV.isVolatileQualified());
1247      } else {
1248        Args.push_back(RV.getAggregateAddr());
1249      }
1250      break;
1251    }
1252
1253    case ABIArgInfo::Ignore:
1254      break;
1255
1256    case ABIArgInfo::Extend:
1257    case ABIArgInfo::Direct: {
1258      if (!isa<llvm::StructType>(ArgInfo.getCoerceToType()) &&
1259          ArgInfo.getCoerceToType() == ConvertType(info_it->type) &&
1260          ArgInfo.getDirectOffset() == 0) {
1261        if (RV.isScalar())
1262          Args.push_back(RV.getScalarVal());
1263        else
1264          Args.push_back(Builder.CreateLoad(RV.getAggregateAddr()));
1265        break;
1266      }
1267
1268      // FIXME: Avoid the conversion through memory if possible.
1269      llvm::Value *SrcPtr;
1270      if (RV.isScalar()) {
1271        SrcPtr = CreateMemTemp(I->Ty, "coerce");
1272        EmitStoreOfScalar(RV.getScalarVal(), SrcPtr, false, Alignment, I->Ty);
1273      } else if (RV.isComplex()) {
1274        SrcPtr = CreateMemTemp(I->Ty, "coerce");
1275        StoreComplexToAddr(RV.getComplexVal(), SrcPtr, false);
1276      } else
1277        SrcPtr = RV.getAggregateAddr();
1278
1279      // If the value is offset in memory, apply the offset now.
1280      if (unsigned Offs = ArgInfo.getDirectOffset()) {
1281        SrcPtr = Builder.CreateBitCast(SrcPtr, Builder.getInt8PtrTy());
1282        SrcPtr = Builder.CreateConstGEP1_32(SrcPtr, Offs);
1283        SrcPtr = Builder.CreateBitCast(SrcPtr,
1284                       llvm::PointerType::getUnqual(ArgInfo.getCoerceToType()));
1285
1286      }
1287
1288      // If the coerce-to type is a first class aggregate, we flatten it and
1289      // pass the elements. Either way is semantically identical, but fast-isel
1290      // and the optimizer generally likes scalar values better than FCAs.
1291      if (const llvm::StructType *STy =
1292            dyn_cast<llvm::StructType>(ArgInfo.getCoerceToType())) {
1293        SrcPtr = Builder.CreateBitCast(SrcPtr,
1294                                       llvm::PointerType::getUnqual(STy));
1295        for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
1296          llvm::Value *EltPtr = Builder.CreateConstGEP2_32(SrcPtr, 0, i);
1297          llvm::LoadInst *LI = Builder.CreateLoad(EltPtr);
1298          // We don't know what we're loading from.
1299          LI->setAlignment(1);
1300          Args.push_back(LI);
1301        }
1302      } else {
1303        // In the simple case, just pass the coerced loaded value.
1304        Args.push_back(CreateCoercedLoad(SrcPtr, ArgInfo.getCoerceToType(),
1305                                         *this));
1306      }
1307
1308      break;
1309    }
1310
1311    case ABIArgInfo::Expand:
1312      ExpandTypeToArgs(I->Ty, RV, Args);
1313      break;
1314    }
1315  }
1316
1317  // If the callee is a bitcast of a function to a varargs pointer to function
1318  // type, check to see if we can remove the bitcast.  This handles some cases
1319  // with unprototyped functions.
1320  if (llvm::ConstantExpr *CE = dyn_cast<llvm::ConstantExpr>(Callee))
1321    if (llvm::Function *CalleeF = dyn_cast<llvm::Function>(CE->getOperand(0))) {
1322      const llvm::PointerType *CurPT=cast<llvm::PointerType>(Callee->getType());
1323      const llvm::FunctionType *CurFT =
1324        cast<llvm::FunctionType>(CurPT->getElementType());
1325      const llvm::FunctionType *ActualFT = CalleeF->getFunctionType();
1326
1327      if (CE->getOpcode() == llvm::Instruction::BitCast &&
1328          ActualFT->getReturnType() == CurFT->getReturnType() &&
1329          ActualFT->getNumParams() == CurFT->getNumParams() &&
1330          ActualFT->getNumParams() == Args.size() &&
1331          (CurFT->isVarArg() || !ActualFT->isVarArg())) {
1332        bool ArgsMatch = true;
1333        for (unsigned i = 0, e = ActualFT->getNumParams(); i != e; ++i)
1334          if (ActualFT->getParamType(i) != CurFT->getParamType(i)) {
1335            ArgsMatch = false;
1336            break;
1337          }
1338
1339        // Strip the cast if we can get away with it.  This is a nice cleanup,
1340        // but also allows us to inline the function at -O0 if it is marked
1341        // always_inline.
1342        if (ArgsMatch)
1343          Callee = CalleeF;
1344      }
1345    }
1346
1347
1348  unsigned CallingConv;
1349  CodeGen::AttributeListType AttributeList;
1350  CGM.ConstructAttributeList(CallInfo, TargetDecl, AttributeList, CallingConv);
1351  llvm::AttrListPtr Attrs = llvm::AttrListPtr::get(AttributeList.begin(),
1352                                                   AttributeList.end());
1353
1354  llvm::BasicBlock *InvokeDest = 0;
1355  if (!(Attrs.getFnAttributes() & llvm::Attribute::NoUnwind))
1356    InvokeDest = getInvokeDest();
1357
1358  llvm::CallSite CS;
1359  if (!InvokeDest) {
1360    CS = Builder.CreateCall(Callee, Args.data(), Args.data()+Args.size());
1361  } else {
1362    llvm::BasicBlock *Cont = createBasicBlock("invoke.cont");
1363    CS = Builder.CreateInvoke(Callee, Cont, InvokeDest,
1364                              Args.data(), Args.data()+Args.size());
1365    EmitBlock(Cont);
1366  }
1367  if (callOrInvoke)
1368    *callOrInvoke = CS.getInstruction();
1369
1370  CS.setAttributes(Attrs);
1371  CS.setCallingConv(static_cast<llvm::CallingConv::ID>(CallingConv));
1372
1373  // If the call doesn't return, finish the basic block and clear the
1374  // insertion point; this allows the rest of IRgen to discard
1375  // unreachable code.
1376  if (CS.doesNotReturn()) {
1377    Builder.CreateUnreachable();
1378    Builder.ClearInsertionPoint();
1379
1380    // FIXME: For now, emit a dummy basic block because expr emitters in
1381    // generally are not ready to handle emitting expressions at unreachable
1382    // points.
1383    EnsureInsertPoint();
1384
1385    // Return a reasonable RValue.
1386    return GetUndefRValue(RetTy);
1387  }
1388
1389  llvm::Instruction *CI = CS.getInstruction();
1390  if (Builder.isNamePreserving() && !CI->getType()->isVoidTy())
1391    CI->setName("call");
1392
1393  switch (RetAI.getKind()) {
1394  case ABIArgInfo::Indirect: {
1395    unsigned Alignment = getContext().getTypeAlignInChars(RetTy).getQuantity();
1396    if (RetTy->isAnyComplexType())
1397      return RValue::getComplex(LoadComplexFromAddr(Args[0], false));
1398    if (CodeGenFunction::hasAggregateLLVMType(RetTy))
1399      return RValue::getAggregate(Args[0]);
1400    return RValue::get(EmitLoadOfScalar(Args[0], false, Alignment, RetTy));
1401  }
1402
1403  case ABIArgInfo::Ignore:
1404    // If we are ignoring an argument that had a result, make sure to
1405    // construct the appropriate return value for our caller.
1406    return GetUndefRValue(RetTy);
1407
1408  case ABIArgInfo::Extend:
1409  case ABIArgInfo::Direct: {
1410    if (RetAI.getCoerceToType() == ConvertType(RetTy) &&
1411        RetAI.getDirectOffset() == 0) {
1412      if (RetTy->isAnyComplexType()) {
1413        llvm::Value *Real = Builder.CreateExtractValue(CI, 0);
1414        llvm::Value *Imag = Builder.CreateExtractValue(CI, 1);
1415        return RValue::getComplex(std::make_pair(Real, Imag));
1416      }
1417      if (CodeGenFunction::hasAggregateLLVMType(RetTy)) {
1418        llvm::Value *DestPtr = ReturnValue.getValue();
1419        bool DestIsVolatile = ReturnValue.isVolatile();
1420
1421        if (!DestPtr) {
1422          DestPtr = CreateMemTemp(RetTy, "agg.tmp");
1423          DestIsVolatile = false;
1424        }
1425        Builder.CreateStore(CI, DestPtr, DestIsVolatile);
1426        return RValue::getAggregate(DestPtr);
1427      }
1428      return RValue::get(CI);
1429    }
1430
1431    llvm::Value *DestPtr = ReturnValue.getValue();
1432    bool DestIsVolatile = ReturnValue.isVolatile();
1433
1434    if (!DestPtr) {
1435      DestPtr = CreateMemTemp(RetTy, "coerce");
1436      DestIsVolatile = false;
1437    }
1438
1439    // If the value is offset in memory, apply the offset now.
1440    llvm::Value *StorePtr = DestPtr;
1441    if (unsigned Offs = RetAI.getDirectOffset()) {
1442      StorePtr = Builder.CreateBitCast(StorePtr, Builder.getInt8PtrTy());
1443      StorePtr = Builder.CreateConstGEP1_32(StorePtr, Offs);
1444      StorePtr = Builder.CreateBitCast(StorePtr,
1445                         llvm::PointerType::getUnqual(RetAI.getCoerceToType()));
1446    }
1447    CreateCoercedStore(CI, StorePtr, DestIsVolatile, *this);
1448
1449    unsigned Alignment = getContext().getTypeAlignInChars(RetTy).getQuantity();
1450    if (RetTy->isAnyComplexType())
1451      return RValue::getComplex(LoadComplexFromAddr(DestPtr, false));
1452    if (CodeGenFunction::hasAggregateLLVMType(RetTy))
1453      return RValue::getAggregate(DestPtr);
1454    return RValue::get(EmitLoadOfScalar(DestPtr, false, Alignment, RetTy));
1455  }
1456
1457  case ABIArgInfo::Expand:
1458    assert(0 && "Invalid ABI kind for return argument");
1459  }
1460
1461  assert(0 && "Unhandled ABIArgInfo::Kind");
1462  return RValue::get(0);
1463}
1464
1465/* VarArg handling */
1466
1467llvm::Value *CodeGenFunction::EmitVAArg(llvm::Value *VAListAddr, QualType Ty) {
1468  return CGM.getTypes().getABIInfo().EmitVAArg(VAListAddr, Ty, *this);
1469}
1470