CGExpr.cpp revision 774e7c6881ee6cb970cd42239d700dce87ed402a 
1//===--- CGExpr.cpp - Emit LLVM Code from Expressions ---------------------===//
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// This contains code to emit Expr nodes as LLVM code.
11//
12//===----------------------------------------------------------------------===//
13
14#include "CodeGenFunction.h"
15#include "CodeGenModule.h"
16#include "CGCall.h"
17#include "CGObjCRuntime.h"
18#include "clang/AST/ASTContext.h"
19#include "clang/AST/DeclObjC.h"
20#include "llvm/Target/TargetData.h"
21using namespace clang;
22using namespace CodeGen;
23
24//===--------------------------------------------------------------------===//
25//                        Miscellaneous Helper Methods
26//===--------------------------------------------------------------------===//
27
28/// CreateTempAlloca - This creates a alloca and inserts it into the entry
29/// block.
30llvm::AllocaInst *CodeGenFunction::CreateTempAlloca(const llvm::Type *Ty,
31                                                    const char *Name) {
32  if (!Builder.isNamePreserving())
33    Name = "";
34  return new llvm::AllocaInst(Ty, 0, Name, AllocaInsertPt);
35}
36
37/// EvaluateExprAsBool - Perform the usual unary conversions on the specified
38/// expression and compare the result against zero, returning an Int1Ty value.
39llvm::Value *CodeGenFunction::EvaluateExprAsBool(const Expr *E) {
40  QualType BoolTy = getContext().BoolTy;
41  if (!E->getType()->isAnyComplexType())
42    return EmitScalarConversion(EmitScalarExpr(E), E->getType(), BoolTy);
43
44  return EmitComplexToScalarConversion(EmitComplexExpr(E), E->getType(),BoolTy);
45}
46
47/// EmitAnyExpr - Emit code to compute the specified expression which can have
48/// any type.  The result is returned as an RValue struct.  If this is an
49/// aggregate expression, the aggloc/agglocvolatile arguments indicate where
50/// the result should be returned.
51RValue CodeGenFunction::EmitAnyExpr(const Expr *E, llvm::Value *AggLoc,
52                                    bool isAggLocVolatile) {
53  if (!hasAggregateLLVMType(E->getType()))
54    return RValue::get(EmitScalarExpr(E));
55  else if (E->getType()->isAnyComplexType())
56    return RValue::getComplex(EmitComplexExpr(E));
57
58  EmitAggExpr(E, AggLoc, isAggLocVolatile);
59  return RValue::getAggregate(AggLoc);
60}
61
62/// EmitAnyExprToTemp - Similary to EmitAnyExpr(), however, the result
63/// will always be accessible even if no aggregate location is
64/// provided.
65RValue CodeGenFunction::EmitAnyExprToTemp(const Expr *E, llvm::Value *AggLoc,
66                                          bool isAggLocVolatile) {
67  if (!AggLoc && hasAggregateLLVMType(E->getType()) &&
68      !E->getType()->isAnyComplexType())
69    AggLoc = CreateTempAlloca(ConvertType(E->getType()), "agg.tmp");
70  return EmitAnyExpr(E, AggLoc, isAggLocVolatile);
71}
72
73/// getAccessedFieldNo - Given an encoded value and a result number, return
74/// the input field number being accessed.
75unsigned CodeGenFunction::getAccessedFieldNo(unsigned Idx,
76                                             const llvm::Constant *Elts) {
77  if (isa<llvm::ConstantAggregateZero>(Elts))
78    return 0;
79
80  return cast<llvm::ConstantInt>(Elts->getOperand(Idx))->getZExtValue();
81}
82
83
84//===----------------------------------------------------------------------===//
85//                         LValue Expression Emission
86//===----------------------------------------------------------------------===//
87
88RValue CodeGenFunction::GetUndefRValue(QualType Ty) {
89  if (Ty->isVoidType()) {
90    return RValue::get(0);
91  } else if (const ComplexType *CTy = Ty->getAsComplexType()) {
92    const llvm::Type *EltTy = ConvertType(CTy->getElementType());
93    llvm::Value *U = llvm::UndefValue::get(EltTy);
94    return RValue::getComplex(std::make_pair(U, U));
95  } else if (hasAggregateLLVMType(Ty)) {
96    const llvm::Type *LTy = llvm::PointerType::getUnqual(ConvertType(Ty));
97    return RValue::getAggregate(llvm::UndefValue::get(LTy));
98  } else {
99    return RValue::get(llvm::UndefValue::get(ConvertType(Ty)));
100  }
101}
102
103RValue CodeGenFunction::EmitUnsupportedRValue(const Expr *E,
104                                              const char *Name) {
105  ErrorUnsupported(E, Name);
106  return GetUndefRValue(E->getType());
107}
108
109LValue CodeGenFunction::EmitUnsupportedLValue(const Expr *E,
110                                              const char *Name) {
111  ErrorUnsupported(E, Name);
112  llvm::Type *Ty = llvm::PointerType::getUnqual(ConvertType(E->getType()));
113  return LValue::MakeAddr(llvm::UndefValue::get(Ty),
114                          E->getType().getCVRQualifiers(),
115                          getContext().getObjCGCAttrKind(E->getType()));
116}
117
118/// EmitLValue - Emit code to compute a designator that specifies the location
119/// of the expression.
120///
121/// This can return one of two things: a simple address or a bitfield
122/// reference.  In either case, the LLVM Value* in the LValue structure is
123/// guaranteed to be an LLVM pointer type.
124///
125/// If this returns a bitfield reference, nothing about the pointee type of
126/// the LLVM value is known: For example, it may not be a pointer to an
127/// integer.
128///
129/// If this returns a normal address, and if the lvalue's C type is fixed
130/// size, this method guarantees that the returned pointer type will point to
131/// an LLVM type of the same size of the lvalue's type.  If the lvalue has a
132/// variable length type, this is not possible.
133///
134LValue CodeGenFunction::EmitLValue(const Expr *E) {
135  switch (E->getStmtClass()) {
136  default: return EmitUnsupportedLValue(E, "l-value expression");
137
138  case Expr::BinaryOperatorClass:
139    return EmitBinaryOperatorLValue(cast<BinaryOperator>(E));
140  case Expr::CallExprClass:
141  case Expr::CXXOperatorCallExprClass:
142    return EmitCallExprLValue(cast<CallExpr>(E));
143  case Expr::VAArgExprClass:
144    return EmitVAArgExprLValue(cast<VAArgExpr>(E));
145  case Expr::DeclRefExprClass:
146  case Expr::QualifiedDeclRefExprClass:
147    return EmitDeclRefLValue(cast<DeclRefExpr>(E));
148  case Expr::ParenExprClass:return EmitLValue(cast<ParenExpr>(E)->getSubExpr());
149  case Expr::PredefinedExprClass:
150    return EmitPredefinedLValue(cast<PredefinedExpr>(E));
151  case Expr::StringLiteralClass:
152    return EmitStringLiteralLValue(cast<StringLiteral>(E));
153  case Expr::ObjCEncodeExprClass:
154    return EmitObjCEncodeExprLValue(cast<ObjCEncodeExpr>(E));
155
156  case Expr::BlockDeclRefExprClass:
157    return EmitBlockDeclRefLValue(cast<BlockDeclRefExpr>(E));
158
159  case Expr::CXXConditionDeclExprClass:
160    return EmitCXXConditionDeclLValue(cast<CXXConditionDeclExpr>(E));
161
162  case Expr::ObjCMessageExprClass:
163    return EmitObjCMessageExprLValue(cast<ObjCMessageExpr>(E));
164  case Expr::ObjCIvarRefExprClass:
165    return EmitObjCIvarRefLValue(cast<ObjCIvarRefExpr>(E));
166  case Expr::ObjCPropertyRefExprClass:
167    return EmitObjCPropertyRefLValue(cast<ObjCPropertyRefExpr>(E));
168  case Expr::ObjCKVCRefExprClass:
169    return EmitObjCKVCRefLValue(cast<ObjCKVCRefExpr>(E));
170  case Expr::ObjCSuperExprClass:
171    return EmitObjCSuperExpr(cast<ObjCSuperExpr>(E));
172
173  case Expr::UnaryOperatorClass:
174    return EmitUnaryOpLValue(cast<UnaryOperator>(E));
175  case Expr::ArraySubscriptExprClass:
176    return EmitArraySubscriptExpr(cast<ArraySubscriptExpr>(E));
177  case Expr::ExtVectorElementExprClass:
178    return EmitExtVectorElementExpr(cast<ExtVectorElementExpr>(E));
179  case Expr::MemberExprClass: return EmitMemberExpr(cast<MemberExpr>(E));
180  case Expr::CompoundLiteralExprClass:
181    return EmitCompoundLiteralLValue(cast<CompoundLiteralExpr>(E));
182  case Expr::ConditionalOperatorClass:
183    return EmitConditionalOperator(cast<ConditionalOperator>(E));
184  case Expr::ChooseExprClass:
185    return EmitLValue(cast<ChooseExpr>(E)->getChosenSubExpr(getContext()));
186  case Expr::ImplicitCastExprClass:
187  case Expr::CStyleCastExprClass:
188  case Expr::CXXFunctionalCastExprClass:
189  case Expr::CXXStaticCastExprClass:
190  case Expr::CXXDynamicCastExprClass:
191  case Expr::CXXReinterpretCastExprClass:
192  case Expr::CXXConstCastExprClass:
193    return EmitCastLValue(cast<CastExpr>(E));
194  }
195}
196
197llvm::Value *CodeGenFunction::EmitLoadOfScalar(llvm::Value *Addr, bool Volatile,
198                                               QualType Ty) {
199  llvm::Value *V = Builder.CreateLoad(Addr, Volatile, "tmp");
200
201  // Bool can have different representation in memory than in
202  // registers.
203  if (Ty->isBooleanType())
204    if (V->getType() != llvm::Type::Int1Ty)
205      V = Builder.CreateTrunc(V, llvm::Type::Int1Ty, "tobool");
206
207  return V;
208}
209
210void CodeGenFunction::EmitStoreOfScalar(llvm::Value *Value, llvm::Value *Addr,
211                                        bool Volatile) {
212  // Handle stores of types which have different representations in
213  // memory and as LLVM values.
214
215  // FIXME: We shouldn't be this loose, we should only do this
216  // conversion when we have a type we know has a different memory
217  // representation (e.g., bool).
218
219  const llvm::Type *SrcTy = Value->getType();
220  const llvm::PointerType *DstPtr = cast<llvm::PointerType>(Addr->getType());
221  if (DstPtr->getElementType() != SrcTy) {
222    const llvm::Type *MemTy =
223      llvm::PointerType::get(SrcTy, DstPtr->getAddressSpace());
224    Addr = Builder.CreateBitCast(Addr, MemTy, "storetmp");
225  }
226
227  Builder.CreateStore(Value, Addr, Volatile);
228}
229
230/// EmitLoadOfLValue - Given an expression that represents a value lvalue,
231/// this method emits the address of the lvalue, then loads the result as an
232/// rvalue, returning the rvalue.
233RValue CodeGenFunction::EmitLoadOfLValue(LValue LV, QualType ExprType) {
234  if (LV.isObjCWeak()) {
235    // load of a __weak object.
236    llvm::Value *AddrWeakObj = LV.getAddress();
237    llvm::Value *read_weak = CGM.getObjCRuntime().EmitObjCWeakRead(*this,
238                                                                   AddrWeakObj);
239    return RValue::get(read_weak);
240  }
241
242  if (LV.isSimple()) {
243    llvm::Value *Ptr = LV.getAddress();
244    const llvm::Type *EltTy =
245      cast<llvm::PointerType>(Ptr->getType())->getElementType();
246
247    // Simple scalar l-value.
248    if (EltTy->isSingleValueType())
249      return RValue::get(EmitLoadOfScalar(Ptr, LV.isVolatileQualified(),
250                                          ExprType));
251
252    assert(ExprType->isFunctionType() && "Unknown scalar value");
253    return RValue::get(Ptr);
254  }
255
256  if (LV.isVectorElt()) {
257    llvm::Value *Vec = Builder.CreateLoad(LV.getVectorAddr(),
258                                          LV.isVolatileQualified(), "tmp");
259    return RValue::get(Builder.CreateExtractElement(Vec, LV.getVectorIdx(),
260                                                    "vecext"));
261  }
262
263  // If this is a reference to a subset of the elements of a vector, either
264  // shuffle the input or extract/insert them as appropriate.
265  if (LV.isExtVectorElt())
266    return EmitLoadOfExtVectorElementLValue(LV, ExprType);
267
268  if (LV.isBitfield())
269    return EmitLoadOfBitfieldLValue(LV, ExprType);
270
271  if (LV.isPropertyRef())
272    return EmitLoadOfPropertyRefLValue(LV, ExprType);
273
274  assert(LV.isKVCRef() && "Unknown LValue type!");
275  return EmitLoadOfKVCRefLValue(LV, ExprType);
276}
277
278RValue CodeGenFunction::EmitLoadOfBitfieldLValue(LValue LV,
279                                                 QualType ExprType) {
280  unsigned StartBit = LV.getBitfieldStartBit();
281  unsigned BitfieldSize = LV.getBitfieldSize();
282  llvm::Value *Ptr = LV.getBitfieldAddr();
283
284  const llvm::Type *EltTy =
285    cast<llvm::PointerType>(Ptr->getType())->getElementType();
286  unsigned EltTySize = CGM.getTargetData().getTypeSizeInBits(EltTy);
287
288  // In some cases the bitfield may straddle two memory locations.
289  // Currently we load the entire bitfield, then do the magic to
290  // sign-extend it if necessary. This results in somewhat more code
291  // than necessary for the common case (one load), since two shifts
292  // accomplish both the masking and sign extension.
293  unsigned LowBits = std::min(BitfieldSize, EltTySize - StartBit);
294  llvm::Value *Val = Builder.CreateLoad(Ptr, LV.isVolatileQualified(), "tmp");
295
296  // Shift to proper location.
297  if (StartBit)
298    Val = Builder.CreateLShr(Val, llvm::ConstantInt::get(EltTy, StartBit),
299                             "bf.lo");
300
301  // Mask off unused bits.
302  llvm::Constant *LowMask =
303    llvm::ConstantInt::get(llvm::APInt::getLowBitsSet(EltTySize, LowBits));
304  Val = Builder.CreateAnd(Val, LowMask, "bf.lo.cleared");
305
306  // Fetch the high bits if necessary.
307  if (LowBits < BitfieldSize) {
308    unsigned HighBits = BitfieldSize - LowBits;
309    llvm::Value *HighPtr =
310      Builder.CreateGEP(Ptr, llvm::ConstantInt::get(llvm::Type::Int32Ty, 1),
311                        "bf.ptr.hi");
312    llvm::Value *HighVal = Builder.CreateLoad(HighPtr,
313                                              LV.isVolatileQualified(),
314                                              "tmp");
315
316    // Mask off unused bits.
317    llvm::Constant *HighMask =
318      llvm::ConstantInt::get(llvm::APInt::getLowBitsSet(EltTySize, HighBits));
319    HighVal = Builder.CreateAnd(HighVal, HighMask, "bf.lo.cleared");
320
321    // Shift to proper location and or in to bitfield value.
322    HighVal = Builder.CreateShl(HighVal,
323                                llvm::ConstantInt::get(EltTy, LowBits));
324    Val = Builder.CreateOr(Val, HighVal, "bf.val");
325  }
326
327  // Sign extend if necessary.
328  if (LV.isBitfieldSigned()) {
329    llvm::Value *ExtraBits = llvm::ConstantInt::get(EltTy,
330                                                    EltTySize - BitfieldSize);
331    Val = Builder.CreateAShr(Builder.CreateShl(Val, ExtraBits),
332                             ExtraBits, "bf.val.sext");
333  }
334
335  // The bitfield type and the normal type differ when the storage sizes
336  // differ (currently just _Bool).
337  Val = Builder.CreateIntCast(Val, ConvertType(ExprType), false, "tmp");
338
339  return RValue::get(Val);
340}
341
342RValue CodeGenFunction::EmitLoadOfPropertyRefLValue(LValue LV,
343                                                    QualType ExprType) {
344  return EmitObjCPropertyGet(LV.getPropertyRefExpr());
345}
346
347RValue CodeGenFunction::EmitLoadOfKVCRefLValue(LValue LV,
348                                               QualType ExprType) {
349  return EmitObjCPropertyGet(LV.getKVCRefExpr());
350}
351
352// If this is a reference to a subset of the elements of a vector, create an
353// appropriate shufflevector.
354RValue CodeGenFunction::EmitLoadOfExtVectorElementLValue(LValue LV,
355                                                         QualType ExprType) {
356  llvm::Value *Vec = Builder.CreateLoad(LV.getExtVectorAddr(),
357                                        LV.isVolatileQualified(), "tmp");
358
359  const llvm::Constant *Elts = LV.getExtVectorElts();
360
361  // If the result of the expression is a non-vector type, we must be
362  // extracting a single element.  Just codegen as an extractelement.
363  const VectorType *ExprVT = ExprType->getAsVectorType();
364  if (!ExprVT) {
365    unsigned InIdx = getAccessedFieldNo(0, Elts);
366    llvm::Value *Elt = llvm::ConstantInt::get(llvm::Type::Int32Ty, InIdx);
367    return RValue::get(Builder.CreateExtractElement(Vec, Elt, "tmp"));
368  }
369
370  // Always use shuffle vector to try to retain the original program structure
371  unsigned NumResultElts = ExprVT->getNumElements();
372
373  llvm::SmallVector<llvm::Constant*, 4> Mask;
374  for (unsigned i = 0; i != NumResultElts; ++i) {
375    unsigned InIdx = getAccessedFieldNo(i, Elts);
376    Mask.push_back(llvm::ConstantInt::get(llvm::Type::Int32Ty, InIdx));
377  }
378
379  llvm::Value *MaskV = llvm::ConstantVector::get(&Mask[0], Mask.size());
380  Vec = Builder.CreateShuffleVector(Vec,
381                                    llvm::UndefValue::get(Vec->getType()),
382                                    MaskV, "tmp");
383  return RValue::get(Vec);
384}
385
386
387
388/// EmitStoreThroughLValue - Store the specified rvalue into the specified
389/// lvalue, where both are guaranteed to the have the same type, and that type
390/// is 'Ty'.
391void CodeGenFunction::EmitStoreThroughLValue(RValue Src, LValue Dst,
392                                             QualType Ty) {
393  if (!Dst.isSimple()) {
394    if (Dst.isVectorElt()) {
395      // Read/modify/write the vector, inserting the new element.
396      llvm::Value *Vec = Builder.CreateLoad(Dst.getVectorAddr(),
397                                            Dst.isVolatileQualified(), "tmp");
398      Vec = Builder.CreateInsertElement(Vec, Src.getScalarVal(),
399                                        Dst.getVectorIdx(), "vecins");
400      Builder.CreateStore(Vec, Dst.getVectorAddr(),Dst.isVolatileQualified());
401      return;
402    }
403
404    // If this is an update of extended vector elements, insert them as
405    // appropriate.
406    if (Dst.isExtVectorElt())
407      return EmitStoreThroughExtVectorComponentLValue(Src, Dst, Ty);
408
409    if (Dst.isBitfield())
410      return EmitStoreThroughBitfieldLValue(Src, Dst, Ty);
411
412    if (Dst.isPropertyRef())
413      return EmitStoreThroughPropertyRefLValue(Src, Dst, Ty);
414
415    if (Dst.isKVCRef())
416      return EmitStoreThroughKVCRefLValue(Src, Dst, Ty);
417
418    assert(0 && "Unknown LValue type");
419  }
420
421  if (Dst.isObjCWeak() && !Dst.isNonGC()) {
422    // load of a __weak object.
423    llvm::Value *LvalueDst = Dst.getAddress();
424    llvm::Value *src = Src.getScalarVal();
425    CGM.getObjCRuntime().EmitObjCWeakAssign(*this, src, LvalueDst);
426    return;
427  }
428
429  if (Dst.isObjCStrong() && !Dst.isNonGC()) {
430    // load of a __strong object.
431    llvm::Value *LvalueDst = Dst.getAddress();
432    llvm::Value *src = Src.getScalarVal();
433#if 0
434    // FIXME. We cannot positively determine if we have an
435    // 'ivar' assignment, object assignment or an unknown
436    // assignment. For now, generate call to objc_assign_strongCast
437    // assignment which is a safe, but consevative assumption.
438    if (Dst.isObjCIvar())
439      CGM.getObjCRuntime().EmitObjCIvarAssign(*this, src, LvalueDst);
440    else
441      CGM.getObjCRuntime().EmitObjCGlobalAssign(*this, src, LvalueDst);
442#endif
443    CGM.getObjCRuntime().EmitObjCStrongCastAssign(*this, src, LvalueDst);
444    return;
445  }
446
447  assert(Src.isScalar() && "Can't emit an agg store with this method");
448  EmitStoreOfScalar(Src.getScalarVal(), Dst.getAddress(),
449                    Dst.isVolatileQualified());
450}
451
452void CodeGenFunction::EmitStoreThroughBitfieldLValue(RValue Src, LValue Dst,
453                                                     QualType Ty,
454                                                     llvm::Value **Result) {
455  unsigned StartBit = Dst.getBitfieldStartBit();
456  unsigned BitfieldSize = Dst.getBitfieldSize();
457  llvm::Value *Ptr = Dst.getBitfieldAddr();
458
459  const llvm::Type *EltTy =
460    cast<llvm::PointerType>(Ptr->getType())->getElementType();
461  unsigned EltTySize = CGM.getTargetData().getTypeSizeInBits(EltTy);
462
463  // Get the new value, cast to the appropriate type and masked to
464  // exactly the size of the bit-field.
465  llvm::Value *SrcVal = Src.getScalarVal();
466  llvm::Value *NewVal = Builder.CreateIntCast(SrcVal, EltTy, false, "tmp");
467  llvm::Constant *Mask =
468    llvm::ConstantInt::get(llvm::APInt::getLowBitsSet(EltTySize, BitfieldSize));
469  NewVal = Builder.CreateAnd(NewVal, Mask, "bf.value");
470
471  // Return the new value of the bit-field, if requested.
472  if (Result) {
473    // Cast back to the proper type for result.
474    const llvm::Type *SrcTy = SrcVal->getType();
475    llvm::Value *SrcTrunc = Builder.CreateIntCast(NewVal, SrcTy, false,
476                                                  "bf.reload.val");
477
478    // Sign extend if necessary.
479    if (Dst.isBitfieldSigned()) {
480      unsigned SrcTySize = CGM.getTargetData().getTypeSizeInBits(SrcTy);
481      llvm::Value *ExtraBits = llvm::ConstantInt::get(SrcTy,
482                                                      SrcTySize - BitfieldSize);
483      SrcTrunc = Builder.CreateAShr(Builder.CreateShl(SrcTrunc, ExtraBits),
484                                    ExtraBits, "bf.reload.sext");
485    }
486
487    *Result = SrcTrunc;
488  }
489
490  // In some cases the bitfield may straddle two memory locations.
491  // Emit the low part first and check to see if the high needs to be
492  // done.
493  unsigned LowBits = std::min(BitfieldSize, EltTySize - StartBit);
494  llvm::Value *LowVal = Builder.CreateLoad(Ptr, Dst.isVolatileQualified(),
495                                           "bf.prev.low");
496
497  // Compute the mask for zero-ing the low part of this bitfield.
498  llvm::Constant *InvMask =
499    llvm::ConstantInt::get(~llvm::APInt::getBitsSet(EltTySize, StartBit,
500                                                    StartBit + LowBits));
501
502  // Compute the new low part as
503  //   LowVal = (LowVal & InvMask) | (NewVal << StartBit),
504  // with the shift of NewVal implicitly stripping the high bits.
505  llvm::Value *NewLowVal =
506    Builder.CreateShl(NewVal, llvm::ConstantInt::get(EltTy, StartBit),
507                      "bf.value.lo");
508  LowVal = Builder.CreateAnd(LowVal, InvMask, "bf.prev.lo.cleared");
509  LowVal = Builder.CreateOr(LowVal, NewLowVal, "bf.new.lo");
510
511  // Write back.
512  Builder.CreateStore(LowVal, Ptr, Dst.isVolatileQualified());
513
514  // If the low part doesn't cover the bitfield emit a high part.
515  if (LowBits < BitfieldSize) {
516    unsigned HighBits = BitfieldSize - LowBits;
517    llvm::Value *HighPtr =
518      Builder.CreateGEP(Ptr, llvm::ConstantInt::get(llvm::Type::Int32Ty, 1),
519                        "bf.ptr.hi");
520    llvm::Value *HighVal = Builder.CreateLoad(HighPtr,
521                                              Dst.isVolatileQualified(),
522                                              "bf.prev.hi");
523
524    // Compute the mask for zero-ing the high part of this bitfield.
525    llvm::Constant *InvMask =
526      llvm::ConstantInt::get(~llvm::APInt::getLowBitsSet(EltTySize, HighBits));
527
528    // Compute the new high part as
529    //   HighVal = (HighVal & InvMask) | (NewVal lshr LowBits),
530    // where the high bits of NewVal have already been cleared and the
531    // shift stripping the low bits.
532    llvm::Value *NewHighVal =
533      Builder.CreateLShr(NewVal, llvm::ConstantInt::get(EltTy, LowBits),
534                        "bf.value.high");
535    HighVal = Builder.CreateAnd(HighVal, InvMask, "bf.prev.hi.cleared");
536    HighVal = Builder.CreateOr(HighVal, NewHighVal, "bf.new.hi");
537
538    // Write back.
539    Builder.CreateStore(HighVal, HighPtr, Dst.isVolatileQualified());
540  }
541}
542
543void CodeGenFunction::EmitStoreThroughPropertyRefLValue(RValue Src,
544                                                        LValue Dst,
545                                                        QualType Ty) {
546  EmitObjCPropertySet(Dst.getPropertyRefExpr(), Src);
547}
548
549void CodeGenFunction::EmitStoreThroughKVCRefLValue(RValue Src,
550                                                   LValue Dst,
551                                                   QualType Ty) {
552  EmitObjCPropertySet(Dst.getKVCRefExpr(), Src);
553}
554
555void CodeGenFunction::EmitStoreThroughExtVectorComponentLValue(RValue Src,
556                                                               LValue Dst,
557                                                               QualType Ty) {
558  // This access turns into a read/modify/write of the vector.  Load the input
559  // value now.
560  llvm::Value *Vec = Builder.CreateLoad(Dst.getExtVectorAddr(),
561                                        Dst.isVolatileQualified(), "tmp");
562  const llvm::Constant *Elts = Dst.getExtVectorElts();
563
564  llvm::Value *SrcVal = Src.getScalarVal();
565
566  if (const VectorType *VTy = Ty->getAsVectorType()) {
567    unsigned NumSrcElts = VTy->getNumElements();
568    unsigned NumDstElts =
569       cast<llvm::VectorType>(Vec->getType())->getNumElements();
570    if (NumDstElts == NumSrcElts) {
571      // Use shuffle vector is the src and destination are the same number
572      // of elements
573      llvm::SmallVector<llvm::Constant*, 4> Mask;
574      for (unsigned i = 0; i != NumSrcElts; ++i) {
575        unsigned InIdx = getAccessedFieldNo(i, Elts);
576        Mask.push_back(llvm::ConstantInt::get(llvm::Type::Int32Ty, InIdx));
577      }
578
579      llvm::Value *MaskV = llvm::ConstantVector::get(&Mask[0], Mask.size());
580      Vec = Builder.CreateShuffleVector(SrcVal,
581                                        llvm::UndefValue::get(Vec->getType()),
582                                        MaskV, "tmp");
583    }
584    else if (NumDstElts > NumSrcElts) {
585      // Extended the source vector to the same length and then shuffle it
586      // into the destination.
587      // FIXME: since we're shuffling with undef, can we just use the indices
588      //        into that?  This could be simpler.
589      llvm::SmallVector<llvm::Constant*, 4> ExtMask;
590      unsigned i;
591      for (i = 0; i != NumSrcElts; ++i)
592        ExtMask.push_back(llvm::ConstantInt::get(llvm::Type::Int32Ty, i));
593      for (; i != NumDstElts; ++i)
594        ExtMask.push_back(llvm::UndefValue::get(llvm::Type::Int32Ty));
595      llvm::Value *ExtMaskV = llvm::ConstantVector::get(&ExtMask[0],
596                                                        ExtMask.size());
597      llvm::Value *ExtSrcVal =
598        Builder.CreateShuffleVector(SrcVal,
599                                    llvm::UndefValue::get(SrcVal->getType()),
600                                    ExtMaskV, "tmp");
601      // build identity
602      llvm::SmallVector<llvm::Constant*, 4> Mask;
603      for (unsigned i = 0; i != NumDstElts; ++i) {
604        Mask.push_back(llvm::ConstantInt::get(llvm::Type::Int32Ty, i));
605      }
606      // modify when what gets shuffled in
607      for (unsigned i = 0; i != NumSrcElts; ++i) {
608        unsigned Idx = getAccessedFieldNo(i, Elts);
609        Mask[Idx] =llvm::ConstantInt::get(llvm::Type::Int32Ty, i+NumDstElts);
610      }
611      llvm::Value *MaskV = llvm::ConstantVector::get(&Mask[0], Mask.size());
612      Vec = Builder.CreateShuffleVector(Vec, ExtSrcVal, MaskV, "tmp");
613    }
614    else {
615      // We should never shorten the vector
616      assert(0 && "unexpected shorten vector length");
617    }
618  } else {
619    // If the Src is a scalar (not a vector) it must be updating one element.
620    unsigned InIdx = getAccessedFieldNo(0, Elts);
621    llvm::Value *Elt = llvm::ConstantInt::get(llvm::Type::Int32Ty, InIdx);
622    Vec = Builder.CreateInsertElement(Vec, SrcVal, Elt, "tmp");
623  }
624
625  Builder.CreateStore(Vec, Dst.getExtVectorAddr(), Dst.isVolatileQualified());
626}
627
628LValue CodeGenFunction::EmitDeclRefLValue(const DeclRefExpr *E) {
629  const VarDecl *VD = dyn_cast<VarDecl>(E->getDecl());
630
631  if (VD && (VD->isBlockVarDecl() || isa<ParmVarDecl>(VD) ||
632        isa<ImplicitParamDecl>(VD))) {
633    LValue LV;
634    if (VD->getStorageClass() == VarDecl::Extern) {
635      LV = LValue::MakeAddr(CGM.GetAddrOfGlobalVar(VD),
636                            E->getType().getCVRQualifiers(),
637                            getContext().getObjCGCAttrKind(E->getType()));
638    }
639    else {
640      llvm::Value *V = LocalDeclMap[VD];
641      assert(V && "DeclRefExpr not entered in LocalDeclMap?");
642      // local variables do not get their gc attribute set.
643      QualType::GCAttrTypes attr = QualType::GCNone;
644      // local static?
645      if (!VD->hasLocalStorage())
646        attr = getContext().getObjCGCAttrKind(E->getType());
647      if (VD->getAttr<BlocksAttr>()) {
648        bool needsCopyDispose = BlockRequiresCopying(VD->getType());
649        const llvm::Type *PtrStructTy = V->getType();
650        const llvm::Type *Ty = PtrStructTy;
651        Ty = llvm::PointerType::get(Ty, 0);
652        V = Builder.CreateStructGEP(V, 1, "forwarding");
653        V = Builder.CreateBitCast(V, Ty);
654        V = Builder.CreateLoad(V, false);
655        V = Builder.CreateBitCast(V, PtrStructTy);
656        V = Builder.CreateStructGEP(V, needsCopyDispose*2 + 4, "x");
657      }
658      LV = LValue::MakeAddr(V, E->getType().getCVRQualifiers(), attr);
659    }
660    LValue::SetObjCNonGC(LV, VD->hasLocalStorage());
661    return LV;
662  } else if (VD && VD->isFileVarDecl()) {
663    LValue LV = LValue::MakeAddr(CGM.GetAddrOfGlobalVar(VD),
664                                 E->getType().getCVRQualifiers(),
665                                 getContext().getObjCGCAttrKind(E->getType()));
666    return LV;
667  } else if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(E->getDecl())) {
668    return LValue::MakeAddr(CGM.GetAddrOfFunction(FD),
669                            E->getType().getCVRQualifiers(),
670                            getContext().getObjCGCAttrKind(E->getType()));
671  }
672  else if (const ImplicitParamDecl *IPD =
673      dyn_cast<ImplicitParamDecl>(E->getDecl())) {
674    llvm::Value *V = LocalDeclMap[IPD];
675    assert(V && "BlockVarDecl not entered in LocalDeclMap?");
676    return LValue::MakeAddr(V, E->getType().getCVRQualifiers(),
677                            getContext().getObjCGCAttrKind(E->getType()));
678  }
679  assert(0 && "Unimp declref");
680  //an invalid LValue, but the assert will
681  //ensure that this point is never reached.
682  return LValue();
683}
684
685LValue CodeGenFunction::EmitBlockDeclRefLValue(const BlockDeclRefExpr *E) {
686  return LValue::MakeAddr(GetAddrOfBlockDecl(E), 0);
687}
688
689LValue CodeGenFunction::EmitUnaryOpLValue(const UnaryOperator *E) {
690  // __extension__ doesn't affect lvalue-ness.
691  if (E->getOpcode() == UnaryOperator::Extension)
692    return EmitLValue(E->getSubExpr());
693
694  QualType ExprTy = getContext().getCanonicalType(E->getSubExpr()->getType());
695  switch (E->getOpcode()) {
696  default: assert(0 && "Unknown unary operator lvalue!");
697  case UnaryOperator::Deref:
698    {
699      QualType T =
700        E->getSubExpr()->getType()->getAsPointerType()->getPointeeType();
701      LValue LV = LValue::MakeAddr(EmitScalarExpr(E->getSubExpr()),
702                                   ExprTy->getAsPointerType()->getPointeeType()
703                                      .getCVRQualifiers(),
704                                   getContext().getObjCGCAttrKind(T));
705     // We should not generate __weak write barrier on indirect reference
706     // of a pointer to object; as in void foo (__weak id *param); *param = 0;
707     // But, we continue to generate __strong write barrier on indirect write
708     // into a pointer to object.
709     if (getContext().getLangOptions().ObjC1 &&
710         getContext().getLangOptions().getGCMode() != LangOptions::NonGC &&
711         LV.isObjCWeak())
712       LValue::SetObjCNonGC(LV, !E->isOBJCGCCandidate());
713     return LV;
714    }
715  case UnaryOperator::Real:
716  case UnaryOperator::Imag:
717    LValue LV = EmitLValue(E->getSubExpr());
718    unsigned Idx = E->getOpcode() == UnaryOperator::Imag;
719    return LValue::MakeAddr(Builder.CreateStructGEP(LV.getAddress(),
720                                                    Idx, "idx"),
721                            ExprTy.getCVRQualifiers());
722  }
723}
724
725LValue CodeGenFunction::EmitStringLiteralLValue(const StringLiteral *E) {
726  return LValue::MakeAddr(CGM.GetAddrOfConstantStringFromLiteral(E), 0);
727}
728
729LValue CodeGenFunction::EmitObjCEncodeExprLValue(const ObjCEncodeExpr *E) {
730  return LValue::MakeAddr(CGM.GetAddrOfConstantStringFromObjCEncode(E), 0);
731}
732
733
734LValue CodeGenFunction::EmitPredefinedFunctionName(unsigned Type) {
735  std::string GlobalVarName;
736
737  switch (Type) {
738  default:
739    assert(0 && "Invalid type");
740  case PredefinedExpr::Func:
741    GlobalVarName = "__func__.";
742    break;
743  case PredefinedExpr::Function:
744    GlobalVarName = "__FUNCTION__.";
745    break;
746  case PredefinedExpr::PrettyFunction:
747    // FIXME:: Demangle C++ method names
748    GlobalVarName = "__PRETTY_FUNCTION__.";
749    break;
750  }
751
752  std::string FunctionName;
753  if(const FunctionDecl *FD = dyn_cast<FunctionDecl>(CurFuncDecl)) {
754    FunctionName = CGM.getMangledName(FD);
755  } else {
756    // Just get the mangled name.
757    FunctionName = CurFn->getName();
758  }
759
760  GlobalVarName += FunctionName;
761  llvm::Constant *C =
762    CGM.GetAddrOfConstantCString(FunctionName, GlobalVarName.c_str());
763  return LValue::MakeAddr(C, 0);
764}
765
766LValue CodeGenFunction::EmitPredefinedLValue(const PredefinedExpr *E) {
767  switch (E->getIdentType()) {
768  default:
769    return EmitUnsupportedLValue(E, "predefined expression");
770  case PredefinedExpr::Func:
771  case PredefinedExpr::Function:
772  case PredefinedExpr::PrettyFunction:
773    return EmitPredefinedFunctionName(E->getIdentType());
774  }
775}
776
777LValue CodeGenFunction::EmitArraySubscriptExpr(const ArraySubscriptExpr *E) {
778  // The index must always be an integer, which is not an aggregate.  Emit it.
779  llvm::Value *Idx = EmitScalarExpr(E->getIdx());
780
781  // If the base is a vector type, then we are forming a vector element lvalue
782  // with this subscript.
783  if (E->getBase()->getType()->isVectorType()) {
784    // Emit the vector as an lvalue to get its address.
785    LValue LHS = EmitLValue(E->getBase());
786    assert(LHS.isSimple() && "Can only subscript lvalue vectors here!");
787    // FIXME: This should properly sign/zero/extend or truncate Idx to i32.
788    return LValue::MakeVectorElt(LHS.getAddress(), Idx,
789      E->getBase()->getType().getCVRQualifiers());
790  }
791
792  // The base must be a pointer, which is not an aggregate.  Emit it.
793  llvm::Value *Base = EmitScalarExpr(E->getBase());
794
795  // Extend or truncate the index type to 32 or 64-bits.
796  QualType IdxTy  = E->getIdx()->getType();
797  bool IdxSigned = IdxTy->isSignedIntegerType();
798  unsigned IdxBitwidth = cast<llvm::IntegerType>(Idx->getType())->getBitWidth();
799  if (IdxBitwidth != LLVMPointerWidth)
800    Idx = Builder.CreateIntCast(Idx, llvm::IntegerType::get(LLVMPointerWidth),
801                                IdxSigned, "idxprom");
802
803  // We know that the pointer points to a type of the correct size, unless the
804  // size is a VLA.
805  if (const VariableArrayType *VAT =
806        getContext().getAsVariableArrayType(E->getType())) {
807    llvm::Value *VLASize = VLASizeMap[VAT];
808
809    Idx = Builder.CreateMul(Idx, VLASize);
810
811    QualType BaseType = getContext().getBaseElementType(VAT);
812
813    uint64_t BaseTypeSize = getContext().getTypeSize(BaseType) / 8;
814    Idx = Builder.CreateUDiv(Idx,
815                             llvm::ConstantInt::get(Idx->getType(),
816                                                    BaseTypeSize));
817  }
818
819  QualType T = E->getBase()->getType();
820  QualType ExprTy = getContext().getCanonicalType(T);
821  T = T->getAsPointerType()->getPointeeType();
822  LValue LV =
823           LValue::MakeAddr(Builder.CreateGEP(Base, Idx, "arrayidx"),
824           ExprTy->getAsPointerType()->getPointeeType().getCVRQualifiers(),
825           getContext().getObjCGCAttrKind(T));
826  if (getContext().getLangOptions().ObjC1 &&
827      getContext().getLangOptions().getGCMode() != LangOptions::NonGC)
828    LValue::SetObjCNonGC(LV, !E->isOBJCGCCandidate());
829  return LV;
830}
831
832static
833llvm::Constant *GenerateConstantVector(llvm::SmallVector<unsigned, 4> &Elts) {
834  llvm::SmallVector<llvm::Constant *, 4> CElts;
835
836  for (unsigned i = 0, e = Elts.size(); i != e; ++i)
837    CElts.push_back(llvm::ConstantInt::get(llvm::Type::Int32Ty, Elts[i]));
838
839  return llvm::ConstantVector::get(&CElts[0], CElts.size());
840}
841
842LValue CodeGenFunction::
843EmitExtVectorElementExpr(const ExtVectorElementExpr *E) {
844  // Emit the base vector as an l-value.
845  LValue Base;
846
847  // ExtVectorElementExpr's base can either be a vector or pointer to vector.
848  if (!E->isArrow()) {
849    assert(E->getBase()->getType()->isVectorType());
850    Base = EmitLValue(E->getBase());
851  } else {
852    const PointerType *PT = E->getBase()->getType()->getAsPointerType();
853    llvm::Value *Ptr = EmitScalarExpr(E->getBase());
854    Base = LValue::MakeAddr(Ptr, PT->getPointeeType().getCVRQualifiers());
855  }
856
857  // Encode the element access list into a vector of unsigned indices.
858  llvm::SmallVector<unsigned, 4> Indices;
859  E->getEncodedElementAccess(Indices);
860
861  if (Base.isSimple()) {
862    llvm::Constant *CV = GenerateConstantVector(Indices);
863    return LValue::MakeExtVectorElt(Base.getAddress(), CV,
864                                    Base.getQualifiers());
865  }
866  assert(Base.isExtVectorElt() && "Can only subscript lvalue vec elts here!");
867
868  llvm::Constant *BaseElts = Base.getExtVectorElts();
869  llvm::SmallVector<llvm::Constant *, 4> CElts;
870
871  for (unsigned i = 0, e = Indices.size(); i != e; ++i) {
872    if (isa<llvm::ConstantAggregateZero>(BaseElts))
873      CElts.push_back(llvm::ConstantInt::get(llvm::Type::Int32Ty, 0));
874    else
875      CElts.push_back(BaseElts->getOperand(Indices[i]));
876  }
877  llvm::Constant *CV = llvm::ConstantVector::get(&CElts[0], CElts.size());
878  return LValue::MakeExtVectorElt(Base.getExtVectorAddr(), CV,
879                                  Base.getQualifiers());
880}
881
882LValue CodeGenFunction::EmitMemberExpr(const MemberExpr *E) {
883  bool isUnion = false;
884  bool isIvar = false;
885  bool isNonGC = false;
886  Expr *BaseExpr = E->getBase();
887  llvm::Value *BaseValue = NULL;
888  unsigned CVRQualifiers=0;
889
890  // If this is s.x, emit s as an lvalue.  If it is s->x, emit s as a scalar.
891  if (E->isArrow()) {
892    BaseValue = EmitScalarExpr(BaseExpr);
893    const PointerType *PTy =
894      cast<PointerType>(getContext().getCanonicalType(BaseExpr->getType()));
895    if (PTy->getPointeeType()->isUnionType())
896      isUnion = true;
897    CVRQualifiers = PTy->getPointeeType().getCVRQualifiers();
898  } else if (isa<ObjCPropertyRefExpr>(BaseExpr) ||
899             isa<ObjCKVCRefExpr>(BaseExpr)) {
900    RValue RV = EmitObjCPropertyGet(BaseExpr);
901    BaseValue = RV.getAggregateAddr();
902    if (BaseExpr->getType()->isUnionType())
903      isUnion = true;
904    CVRQualifiers = BaseExpr->getType().getCVRQualifiers();
905  } else {
906    LValue BaseLV = EmitLValue(BaseExpr);
907    if (BaseLV.isObjCIvar())
908      isIvar = true;
909    if (BaseLV.isNonGC())
910      isNonGC = true;
911    // FIXME: this isn't right for bitfields.
912    BaseValue = BaseLV.getAddress();
913    if (BaseExpr->getType()->isUnionType())
914      isUnion = true;
915    CVRQualifiers = BaseExpr->getType().getCVRQualifiers();
916  }
917
918  FieldDecl *Field = dyn_cast<FieldDecl>(E->getMemberDecl());
919  // FIXME: Handle non-field member expressions
920  assert(Field && "No code generation for non-field member references");
921  LValue MemExpLV = EmitLValueForField(BaseValue, Field, isUnion,
922                                       CVRQualifiers);
923  LValue::SetObjCIvar(MemExpLV, isIvar);
924  LValue::SetObjCNonGC(MemExpLV, isNonGC);
925  return MemExpLV;
926}
927
928LValue CodeGenFunction::EmitLValueForBitfield(llvm::Value* BaseValue,
929                                              FieldDecl* Field,
930                                              unsigned CVRQualifiers) {
931   unsigned idx = CGM.getTypes().getLLVMFieldNo(Field);
932  // FIXME: CodeGenTypes should expose a method to get the appropriate
933  // type for FieldTy (the appropriate type is ABI-dependent).
934  const llvm::Type *FieldTy =
935    CGM.getTypes().ConvertTypeForMem(Field->getType());
936  const llvm::PointerType *BaseTy =
937  cast<llvm::PointerType>(BaseValue->getType());
938  unsigned AS = BaseTy->getAddressSpace();
939  BaseValue = Builder.CreateBitCast(BaseValue,
940                                    llvm::PointerType::get(FieldTy, AS),
941                                    "tmp");
942  llvm::Value *V = Builder.CreateGEP(BaseValue,
943                              llvm::ConstantInt::get(llvm::Type::Int32Ty, idx),
944                              "tmp");
945
946  CodeGenTypes::BitFieldInfo bitFieldInfo =
947    CGM.getTypes().getBitFieldInfo(Field);
948  return LValue::MakeBitfield(V, bitFieldInfo.Begin, bitFieldInfo.Size,
949                              Field->getType()->isSignedIntegerType(),
950                            Field->getType().getCVRQualifiers()|CVRQualifiers);
951}
952
953LValue CodeGenFunction::EmitLValueForField(llvm::Value* BaseValue,
954                                           FieldDecl* Field,
955                                           bool isUnion,
956                                           unsigned CVRQualifiers)
957{
958  if (Field->isBitField())
959    return EmitLValueForBitfield(BaseValue, Field, CVRQualifiers);
960
961  unsigned idx = CGM.getTypes().getLLVMFieldNo(Field);
962  llvm::Value *V = Builder.CreateStructGEP(BaseValue, idx, "tmp");
963
964  // Match union field type.
965  if (isUnion) {
966    const llvm::Type *FieldTy =
967      CGM.getTypes().ConvertTypeForMem(Field->getType());
968    const llvm::PointerType * BaseTy =
969      cast<llvm::PointerType>(BaseValue->getType());
970    unsigned AS = BaseTy->getAddressSpace();
971    V = Builder.CreateBitCast(V,
972                              llvm::PointerType::get(FieldTy, AS),
973                              "tmp");
974  }
975
976  QualType::GCAttrTypes attr = QualType::GCNone;
977  if (CGM.getLangOptions().ObjC1 &&
978      CGM.getLangOptions().getGCMode() != LangOptions::NonGC) {
979    QualType Ty = Field->getType();
980    attr = Ty.getObjCGCAttr();
981    if (attr != QualType::GCNone) {
982      // __weak attribute on a field is ignored.
983      if (attr == QualType::Weak)
984        attr = QualType::GCNone;
985    }
986    else if (getContext().isObjCObjectPointerType(Ty))
987      attr = QualType::Strong;
988  }
989  LValue LV =
990    LValue::MakeAddr(V,
991                     Field->getType().getCVRQualifiers()|CVRQualifiers,
992                     attr);
993  return LV;
994}
995
996LValue CodeGenFunction::EmitCompoundLiteralLValue(const CompoundLiteralExpr* E){
997  const llvm::Type *LTy = ConvertType(E->getType());
998  llvm::Value *DeclPtr = CreateTempAlloca(LTy, ".compoundliteral");
999
1000  const Expr* InitExpr = E->getInitializer();
1001  LValue Result = LValue::MakeAddr(DeclPtr, E->getType().getCVRQualifiers());
1002
1003  if (E->getType()->isComplexType()) {
1004    EmitComplexExprIntoAddr(InitExpr, DeclPtr, false);
1005  } else if (hasAggregateLLVMType(E->getType())) {
1006    EmitAnyExpr(InitExpr, DeclPtr, false);
1007  } else {
1008    EmitStoreThroughLValue(EmitAnyExpr(InitExpr), Result, E->getType());
1009  }
1010
1011  return Result;
1012}
1013
1014LValue CodeGenFunction::EmitConditionalOperator(const ConditionalOperator* E) {
1015  // We don't handle vectors yet.
1016  if (E->getType()->isVectorType())
1017    return EmitUnsupportedLValue(E, "conditional operator");
1018
1019  // ?: here should be an aggregate.
1020  assert((hasAggregateLLVMType(E->getType()) &&
1021          !E->getType()->isAnyComplexType()) &&
1022         "Unexpected conditional operator!");
1023
1024  llvm::Value *Temp = CreateTempAlloca(ConvertType(E->getType()));
1025  EmitAggExpr(E, Temp, false);
1026
1027  return LValue::MakeAddr(Temp, E->getType().getCVRQualifiers(),
1028                          getContext().getObjCGCAttrKind(E->getType()));
1029
1030}
1031
1032/// EmitCastLValue - Casts are never lvalues.  If a cast is needed by the code
1033/// generator in an lvalue context, then it must mean that we need the address
1034/// of an aggregate in order to access one of its fields.  This can happen for
1035/// all the reasons that casts are permitted with aggregate result, including
1036/// noop aggregate casts, and cast from scalar to union.
1037LValue CodeGenFunction::EmitCastLValue(const CastExpr *E) {
1038  // If this is an aggregate-to-aggregate cast, just use the input's address as
1039  // the lvalue.
1040  if (getContext().hasSameUnqualifiedType(E->getType(),
1041                                          E->getSubExpr()->getType()))
1042    return EmitLValue(E->getSubExpr());
1043
1044  // Otherwise, we must have a cast from scalar to union.
1045  assert(E->getType()->isUnionType() && "Expected scalar-to-union cast");
1046
1047  // Casts are only lvalues when the source and destination types are the same.
1048  llvm::Value *Temp = CreateTempAlloca(ConvertType(E->getType()));
1049  EmitAnyExpr(E->getSubExpr(), Temp, false);
1050
1051  return LValue::MakeAddr(Temp, E->getType().getCVRQualifiers(),
1052                          getContext().getObjCGCAttrKind(E->getType()));
1053}
1054
1055//===--------------------------------------------------------------------===//
1056//                             Expression Emission
1057//===--------------------------------------------------------------------===//
1058
1059
1060RValue CodeGenFunction::EmitCallExpr(const CallExpr *E) {
1061  // Builtins never have block type.
1062  if (E->getCallee()->getType()->isBlockPointerType())
1063    return EmitBlockCallExpr(E);
1064
1065  if (const CXXMemberCallExpr *CE = dyn_cast<CXXMemberCallExpr>(E))
1066    return EmitCXXMemberCallExpr(CE);
1067
1068  const Decl *TargetDecl = 0;
1069  if (const ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(E->getCallee())) {
1070    if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(CE->getSubExpr())) {
1071      TargetDecl = DRE->getDecl();
1072      if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(TargetDecl))
1073        if (unsigned builtinID = FD->getBuiltinID(getContext()))
1074          return EmitBuiltinExpr(FD, builtinID, E);
1075    }
1076  }
1077
1078  llvm::Value *Callee = EmitScalarExpr(E->getCallee());
1079  return EmitCallExpr(Callee, E->getCallee()->getType(),
1080                      E->arg_begin(), E->arg_end(), TargetDecl);
1081}
1082
1083LValue CodeGenFunction::EmitBinaryOperatorLValue(const BinaryOperator *E) {
1084  // Can only get l-value for binary operator expressions which are a
1085  // simple assignment of aggregate type.
1086  if (E->getOpcode() != BinaryOperator::Assign)
1087    return EmitUnsupportedLValue(E, "binary l-value expression");
1088
1089  llvm::Value *Temp = CreateTempAlloca(ConvertType(E->getType()));
1090  EmitAggExpr(E, Temp, false);
1091  // FIXME: Are these qualifiers correct?
1092  return LValue::MakeAddr(Temp, E->getType().getCVRQualifiers(),
1093                          getContext().getObjCGCAttrKind(E->getType()));
1094}
1095
1096LValue CodeGenFunction::EmitCallExprLValue(const CallExpr *E) {
1097  // Can only get l-value for call expression returning aggregate type
1098  RValue RV = EmitCallExpr(E);
1099  return LValue::MakeAddr(RV.getAggregateAddr(),
1100                          E->getType().getCVRQualifiers(),
1101                          getContext().getObjCGCAttrKind(E->getType()));
1102}
1103
1104LValue CodeGenFunction::EmitVAArgExprLValue(const VAArgExpr *E) {
1105  // FIXME: This shouldn't require another copy.
1106  llvm::Value *Temp = CreateTempAlloca(ConvertType(E->getType()));
1107  EmitAggExpr(E, Temp, false);
1108  return LValue::MakeAddr(Temp, E->getType().getCVRQualifiers());
1109}
1110
1111LValue
1112CodeGenFunction::EmitCXXConditionDeclLValue(const CXXConditionDeclExpr *E) {
1113  EmitLocalBlockVarDecl(*E->getVarDecl());
1114  return EmitDeclRefLValue(E);
1115}
1116
1117LValue CodeGenFunction::EmitObjCMessageExprLValue(const ObjCMessageExpr *E) {
1118  // Can only get l-value for message expression returning aggregate type
1119  RValue RV = EmitObjCMessageExpr(E);
1120  // FIXME: can this be volatile?
1121  return LValue::MakeAddr(RV.getAggregateAddr(),
1122                          E->getType().getCVRQualifiers(),
1123                          getContext().getObjCGCAttrKind(E->getType()));
1124}
1125
1126llvm::Value *CodeGenFunction::EmitIvarOffset(ObjCInterfaceDecl *Interface,
1127                                             const ObjCIvarDecl *Ivar) {
1128  // Objective-C objects are traditionally C structures with their layout
1129  // defined at compile-time.  In some implementations, their layout is not
1130  // defined until run time in order to allow instance variables to be added to
1131  // a class without recompiling all of the subclasses.  If this is the case
1132  // then the CGObjCRuntime subclass must return true to LateBoundIvars and
1133  // implement the lookup itself.
1134  if (CGM.getObjCRuntime().LateBoundIVars())
1135    assert(0 && "late-bound ivars are unsupported");
1136  return CGM.getObjCRuntime().EmitIvarOffset(*this, Interface, Ivar);
1137}
1138
1139LValue CodeGenFunction::EmitLValueForIvar(QualType ObjectTy,
1140                                          llvm::Value *BaseValue,
1141                                          const ObjCIvarDecl *Ivar,
1142                                          const FieldDecl *Field,
1143                                          unsigned CVRQualifiers) {
1144  // See comment in EmitIvarOffset.
1145  if (CGM.getObjCRuntime().LateBoundIVars())
1146    assert(0 && "late-bound ivars are unsupported");
1147
1148  LValue LV = CGM.getObjCRuntime().EmitObjCValueForIvar(*this,
1149                                                        ObjectTy,
1150                                                        BaseValue, Ivar, Field,
1151                                                        CVRQualifiers);
1152  return LV;
1153}
1154
1155LValue CodeGenFunction::EmitObjCIvarRefLValue(const ObjCIvarRefExpr *E) {
1156  // FIXME: A lot of the code below could be shared with EmitMemberExpr.
1157  llvm::Value *BaseValue = 0;
1158  const Expr *BaseExpr = E->getBase();
1159  unsigned CVRQualifiers = 0;
1160  QualType ObjectTy;
1161  if (E->isArrow()) {
1162    BaseValue = EmitScalarExpr(BaseExpr);
1163    const PointerType *PTy =
1164      cast<PointerType>(getContext().getCanonicalType(BaseExpr->getType()));
1165    ObjectTy = PTy->getPointeeType();
1166    CVRQualifiers = ObjectTy.getCVRQualifiers();
1167  } else {
1168    LValue BaseLV = EmitLValue(BaseExpr);
1169    // FIXME: this isn't right for bitfields.
1170    BaseValue = BaseLV.getAddress();
1171    ObjectTy = BaseExpr->getType();
1172    CVRQualifiers = ObjectTy.getCVRQualifiers();
1173  }
1174
1175  return EmitLValueForIvar(ObjectTy, BaseValue, E->getDecl(),
1176                           getContext().getFieldDecl(E), CVRQualifiers);
1177}
1178
1179LValue
1180CodeGenFunction::EmitObjCPropertyRefLValue(const ObjCPropertyRefExpr *E) {
1181  // This is a special l-value that just issues sends when we load or
1182  // store through it.
1183  return LValue::MakePropertyRef(E, E->getType().getCVRQualifiers());
1184}
1185
1186LValue
1187CodeGenFunction::EmitObjCKVCRefLValue(const ObjCKVCRefExpr *E) {
1188  // This is a special l-value that just issues sends when we load or
1189  // store through it.
1190  return LValue::MakeKVCRef(E, E->getType().getCVRQualifiers());
1191}
1192
1193LValue
1194CodeGenFunction::EmitObjCSuperExpr(const ObjCSuperExpr *E) {
1195  return EmitUnsupportedLValue(E, "use of super");
1196}
1197
1198RValue CodeGenFunction::EmitCallExpr(llvm::Value *Callee, QualType CalleeType,
1199                                     CallExpr::const_arg_iterator ArgBeg,
1200                                     CallExpr::const_arg_iterator ArgEnd,
1201                                     const Decl *TargetDecl) {
1202  // Get the actual function type. The callee type will always be a
1203  // pointer to function type or a block pointer type.
1204  QualType ResultType;
1205  if (const BlockPointerType *BPT = dyn_cast<BlockPointerType>(CalleeType)) {
1206    ResultType = BPT->getPointeeType()->getAsFunctionType()->getResultType();
1207  } else {
1208    assert(CalleeType->isFunctionPointerType() &&
1209           "Call must have function pointer type!");
1210    QualType FnType = CalleeType->getAsPointerType()->getPointeeType();
1211    ResultType = FnType->getAsFunctionType()->getResultType();
1212  }
1213
1214  CallArgList Args;
1215  for (CallExpr::const_arg_iterator I = ArgBeg; I != ArgEnd; ++I)
1216    Args.push_back(std::make_pair(EmitAnyExprToTemp(*I),
1217                                  I->getType()));
1218
1219  return EmitCall(CGM.getTypes().getFunctionInfo(ResultType, Args),
1220                  Callee, Args, TargetDecl);
1221}
1222