CGExpr.cpp revision aa771a838a8f39633947ccc597e11d57e2839089 
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    bool GCable = VD->hasLocalStorage() && !VD->hasAttr<BlocksAttr>();
635    if (VD->hasExternalStorage()) {
636      LV = LValue::MakeAddr(CGM.GetAddrOfGlobalVar(VD),
637                            E->getType().getCVRQualifiers(),
638                            getContext().getObjCGCAttrKind(E->getType()));
639    }
640    else {
641      llvm::Value *V = LocalDeclMap[VD];
642      assert(V && "DeclRefExpr not entered in LocalDeclMap?");
643      // local variables do not get their gc attribute set.
644      QualType::GCAttrTypes attr = QualType::GCNone;
645      // local static?
646      if (!GCable)
647        attr = getContext().getObjCGCAttrKind(E->getType());
648      if (VD->hasAttr<BlocksAttr>()) {
649        bool needsCopyDispose = BlockRequiresCopying(VD->getType());
650        const llvm::Type *PtrStructTy = V->getType();
651        const llvm::Type *Ty = PtrStructTy;
652        Ty = llvm::PointerType::get(Ty, 0);
653        V = Builder.CreateStructGEP(V, 1, "forwarding");
654        V = Builder.CreateBitCast(V, Ty);
655        V = Builder.CreateLoad(V, false);
656        V = Builder.CreateBitCast(V, PtrStructTy);
657        V = Builder.CreateStructGEP(V, needsCopyDispose*2 + 4, "x");
658      }
659      LV = LValue::MakeAddr(V, E->getType().getCVRQualifiers(), attr);
660    }
661    LValue::SetObjCNonGC(LV, GCable);
662    return LV;
663  } else if (VD && VD->isFileVarDecl()) {
664    LValue LV = LValue::MakeAddr(CGM.GetAddrOfGlobalVar(VD),
665                                 E->getType().getCVRQualifiers(),
666                                 getContext().getObjCGCAttrKind(E->getType()));
667    return LV;
668  } else if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(E->getDecl())) {
669    return LValue::MakeAddr(CGM.GetAddrOfFunction(FD),
670                            E->getType().getCVRQualifiers(),
671                            getContext().getObjCGCAttrKind(E->getType()));
672  }
673  else if (const ImplicitParamDecl *IPD =
674      dyn_cast<ImplicitParamDecl>(E->getDecl())) {
675    llvm::Value *V = LocalDeclMap[IPD];
676    assert(V && "BlockVarDecl not entered in LocalDeclMap?");
677    return LValue::MakeAddr(V, E->getType().getCVRQualifiers(),
678                            getContext().getObjCGCAttrKind(E->getType()));
679  }
680  assert(0 && "Unimp declref");
681  //an invalid LValue, but the assert will
682  //ensure that this point is never reached.
683  return LValue();
684}
685
686LValue CodeGenFunction::EmitBlockDeclRefLValue(const BlockDeclRefExpr *E) {
687  return LValue::MakeAddr(GetAddrOfBlockDecl(E), 0);
688}
689
690LValue CodeGenFunction::EmitUnaryOpLValue(const UnaryOperator *E) {
691  // __extension__ doesn't affect lvalue-ness.
692  if (E->getOpcode() == UnaryOperator::Extension)
693    return EmitLValue(E->getSubExpr());
694
695  QualType ExprTy = getContext().getCanonicalType(E->getSubExpr()->getType());
696  switch (E->getOpcode()) {
697  default: assert(0 && "Unknown unary operator lvalue!");
698  case UnaryOperator::Deref:
699    {
700      QualType T =
701        E->getSubExpr()->getType()->getAsPointerType()->getPointeeType();
702      LValue LV = LValue::MakeAddr(EmitScalarExpr(E->getSubExpr()),
703                                   ExprTy->getAsPointerType()->getPointeeType()
704                                      .getCVRQualifiers(),
705                                   getContext().getObjCGCAttrKind(T));
706     // We should not generate __weak write barrier on indirect reference
707     // of a pointer to object; as in void foo (__weak id *param); *param = 0;
708     // But, we continue to generate __strong write barrier on indirect write
709     // into a pointer to object.
710     if (getContext().getLangOptions().ObjC1 &&
711         getContext().getLangOptions().getGCMode() != LangOptions::NonGC &&
712         LV.isObjCWeak())
713       LValue::SetObjCNonGC(LV, !E->isOBJCGCCandidate());
714     return LV;
715    }
716  case UnaryOperator::Real:
717  case UnaryOperator::Imag:
718    LValue LV = EmitLValue(E->getSubExpr());
719    unsigned Idx = E->getOpcode() == UnaryOperator::Imag;
720    return LValue::MakeAddr(Builder.CreateStructGEP(LV.getAddress(),
721                                                    Idx, "idx"),
722                            ExprTy.getCVRQualifiers());
723  }
724}
725
726LValue CodeGenFunction::EmitStringLiteralLValue(const StringLiteral *E) {
727  return LValue::MakeAddr(CGM.GetAddrOfConstantStringFromLiteral(E), 0);
728}
729
730LValue CodeGenFunction::EmitObjCEncodeExprLValue(const ObjCEncodeExpr *E) {
731  return LValue::MakeAddr(CGM.GetAddrOfConstantStringFromObjCEncode(E), 0);
732}
733
734
735LValue CodeGenFunction::EmitPredefinedFunctionName(unsigned Type) {
736  std::string GlobalVarName;
737
738  switch (Type) {
739  default:
740    assert(0 && "Invalid type");
741  case PredefinedExpr::Func:
742    GlobalVarName = "__func__.";
743    break;
744  case PredefinedExpr::Function:
745    GlobalVarName = "__FUNCTION__.";
746    break;
747  case PredefinedExpr::PrettyFunction:
748    // FIXME:: Demangle C++ method names
749    GlobalVarName = "__PRETTY_FUNCTION__.";
750    break;
751  }
752
753  std::string FunctionName;
754  if(const FunctionDecl *FD = dyn_cast<FunctionDecl>(CurFuncDecl)) {
755    FunctionName = CGM.getMangledName(FD);
756  } else {
757    // Just get the mangled name; skipping the asm prefix if it
758    // exists.
759    FunctionName = CurFn->getName();
760    if (FunctionName[0] == '\01')
761      FunctionName = FunctionName.substr(1, std::string::npos);
762  }
763
764  GlobalVarName += FunctionName;
765  llvm::Constant *C =
766    CGM.GetAddrOfConstantCString(FunctionName, GlobalVarName.c_str());
767  return LValue::MakeAddr(C, 0);
768}
769
770LValue CodeGenFunction::EmitPredefinedLValue(const PredefinedExpr *E) {
771  switch (E->getIdentType()) {
772  default:
773    return EmitUnsupportedLValue(E, "predefined expression");
774  case PredefinedExpr::Func:
775  case PredefinedExpr::Function:
776  case PredefinedExpr::PrettyFunction:
777    return EmitPredefinedFunctionName(E->getIdentType());
778  }
779}
780
781LValue CodeGenFunction::EmitArraySubscriptExpr(const ArraySubscriptExpr *E) {
782  // The index must always be an integer, which is not an aggregate.  Emit it.
783  llvm::Value *Idx = EmitScalarExpr(E->getIdx());
784
785  // If the base is a vector type, then we are forming a vector element lvalue
786  // with this subscript.
787  if (E->getBase()->getType()->isVectorType()) {
788    // Emit the vector as an lvalue to get its address.
789    LValue LHS = EmitLValue(E->getBase());
790    assert(LHS.isSimple() && "Can only subscript lvalue vectors here!");
791    // FIXME: This should properly sign/zero/extend or truncate Idx to i32.
792    return LValue::MakeVectorElt(LHS.getAddress(), Idx,
793      E->getBase()->getType().getCVRQualifiers());
794  }
795
796  // The base must be a pointer, which is not an aggregate.  Emit it.
797  llvm::Value *Base = EmitScalarExpr(E->getBase());
798
799  // Extend or truncate the index type to 32 or 64-bits.
800  QualType IdxTy  = E->getIdx()->getType();
801  bool IdxSigned = IdxTy->isSignedIntegerType();
802  unsigned IdxBitwidth = cast<llvm::IntegerType>(Idx->getType())->getBitWidth();
803
804  // If Pointer width is less than 32 than extend to 32.
805  unsigned IdxValidWidth = (LLVMPointerWidth < 32 ) ? 32 : LLVMPointerWidth;
806  if (IdxBitwidth != IdxValidWidth)
807    Idx = Builder.CreateIntCast(Idx, llvm::IntegerType::get(IdxValidWidth),
808                                IdxSigned, "idxprom");
809
810  // We know that the pointer points to a type of the correct size, unless the
811  // size is a VLA.
812  if (const VariableArrayType *VAT =
813        getContext().getAsVariableArrayType(E->getType())) {
814    llvm::Value *VLASize = VLASizeMap[VAT];
815
816    Idx = Builder.CreateMul(Idx, VLASize);
817
818    QualType BaseType = getContext().getBaseElementType(VAT);
819
820    uint64_t BaseTypeSize = getContext().getTypeSize(BaseType) / 8;
821    Idx = Builder.CreateUDiv(Idx,
822                             llvm::ConstantInt::get(Idx->getType(),
823                                                    BaseTypeSize));
824  }
825
826  QualType T = E->getBase()->getType();
827  QualType ExprTy = getContext().getCanonicalType(T);
828  T = T->getAsPointerType()->getPointeeType();
829  LValue LV =
830           LValue::MakeAddr(Builder.CreateGEP(Base, Idx, "arrayidx"),
831           ExprTy->getAsPointerType()->getPointeeType().getCVRQualifiers(),
832           getContext().getObjCGCAttrKind(T));
833  if (getContext().getLangOptions().ObjC1 &&
834      getContext().getLangOptions().getGCMode() != LangOptions::NonGC)
835    LValue::SetObjCNonGC(LV, !E->isOBJCGCCandidate());
836  return LV;
837}
838
839static
840llvm::Constant *GenerateConstantVector(llvm::SmallVector<unsigned, 4> &Elts) {
841  llvm::SmallVector<llvm::Constant *, 4> CElts;
842
843  for (unsigned i = 0, e = Elts.size(); i != e; ++i)
844    CElts.push_back(llvm::ConstantInt::get(llvm::Type::Int32Ty, Elts[i]));
845
846  return llvm::ConstantVector::get(&CElts[0], CElts.size());
847}
848
849LValue CodeGenFunction::
850EmitExtVectorElementExpr(const ExtVectorElementExpr *E) {
851  // Emit the base vector as an l-value.
852  LValue Base;
853
854  // ExtVectorElementExpr's base can either be a vector or pointer to vector.
855  if (!E->isArrow()) {
856    assert(E->getBase()->getType()->isVectorType());
857    Base = EmitLValue(E->getBase());
858  } else {
859    const PointerType *PT = E->getBase()->getType()->getAsPointerType();
860    llvm::Value *Ptr = EmitScalarExpr(E->getBase());
861    Base = LValue::MakeAddr(Ptr, PT->getPointeeType().getCVRQualifiers());
862  }
863
864  // Encode the element access list into a vector of unsigned indices.
865  llvm::SmallVector<unsigned, 4> Indices;
866  E->getEncodedElementAccess(Indices);
867
868  if (Base.isSimple()) {
869    llvm::Constant *CV = GenerateConstantVector(Indices);
870    return LValue::MakeExtVectorElt(Base.getAddress(), CV,
871                                    Base.getQualifiers());
872  }
873  assert(Base.isExtVectorElt() && "Can only subscript lvalue vec elts here!");
874
875  llvm::Constant *BaseElts = Base.getExtVectorElts();
876  llvm::SmallVector<llvm::Constant *, 4> CElts;
877
878  for (unsigned i = 0, e = Indices.size(); i != e; ++i) {
879    if (isa<llvm::ConstantAggregateZero>(BaseElts))
880      CElts.push_back(llvm::ConstantInt::get(llvm::Type::Int32Ty, 0));
881    else
882      CElts.push_back(BaseElts->getOperand(Indices[i]));
883  }
884  llvm::Constant *CV = llvm::ConstantVector::get(&CElts[0], CElts.size());
885  return LValue::MakeExtVectorElt(Base.getExtVectorAddr(), CV,
886                                  Base.getQualifiers());
887}
888
889LValue CodeGenFunction::EmitMemberExpr(const MemberExpr *E) {
890  bool isUnion = false;
891  bool isIvar = false;
892  bool isNonGC = false;
893  Expr *BaseExpr = E->getBase();
894  llvm::Value *BaseValue = NULL;
895  unsigned CVRQualifiers=0;
896
897  // If this is s.x, emit s as an lvalue.  If it is s->x, emit s as a scalar.
898  if (E->isArrow()) {
899    BaseValue = EmitScalarExpr(BaseExpr);
900    const PointerType *PTy =
901      cast<PointerType>(getContext().getCanonicalType(BaseExpr->getType()));
902    if (PTy->getPointeeType()->isUnionType())
903      isUnion = true;
904    CVRQualifiers = PTy->getPointeeType().getCVRQualifiers();
905  } else if (isa<ObjCPropertyRefExpr>(BaseExpr) ||
906             isa<ObjCKVCRefExpr>(BaseExpr)) {
907    RValue RV = EmitObjCPropertyGet(BaseExpr);
908    BaseValue = RV.getAggregateAddr();
909    if (BaseExpr->getType()->isUnionType())
910      isUnion = true;
911    CVRQualifiers = BaseExpr->getType().getCVRQualifiers();
912  } else {
913    LValue BaseLV = EmitLValue(BaseExpr);
914    if (BaseLV.isObjCIvar())
915      isIvar = true;
916    if (BaseLV.isNonGC())
917      isNonGC = true;
918    // FIXME: this isn't right for bitfields.
919    BaseValue = BaseLV.getAddress();
920    if (BaseExpr->getType()->isUnionType())
921      isUnion = true;
922    CVRQualifiers = BaseExpr->getType().getCVRQualifiers();
923  }
924
925  FieldDecl *Field = dyn_cast<FieldDecl>(E->getMemberDecl());
926  // FIXME: Handle non-field member expressions
927  assert(Field && "No code generation for non-field member references");
928  LValue MemExpLV = EmitLValueForField(BaseValue, Field, isUnion,
929                                       CVRQualifiers);
930  LValue::SetObjCIvar(MemExpLV, isIvar);
931  LValue::SetObjCNonGC(MemExpLV, isNonGC);
932  return MemExpLV;
933}
934
935LValue CodeGenFunction::EmitLValueForBitfield(llvm::Value* BaseValue,
936                                              FieldDecl* Field,
937                                              unsigned CVRQualifiers) {
938   unsigned idx = CGM.getTypes().getLLVMFieldNo(Field);
939  // FIXME: CodeGenTypes should expose a method to get the appropriate
940  // type for FieldTy (the appropriate type is ABI-dependent).
941  const llvm::Type *FieldTy =
942    CGM.getTypes().ConvertTypeForMem(Field->getType());
943  const llvm::PointerType *BaseTy =
944  cast<llvm::PointerType>(BaseValue->getType());
945  unsigned AS = BaseTy->getAddressSpace();
946  BaseValue = Builder.CreateBitCast(BaseValue,
947                                    llvm::PointerType::get(FieldTy, AS),
948                                    "tmp");
949  llvm::Value *V = Builder.CreateGEP(BaseValue,
950                              llvm::ConstantInt::get(llvm::Type::Int32Ty, idx),
951                              "tmp");
952
953  CodeGenTypes::BitFieldInfo bitFieldInfo =
954    CGM.getTypes().getBitFieldInfo(Field);
955  return LValue::MakeBitfield(V, bitFieldInfo.Begin, bitFieldInfo.Size,
956                              Field->getType()->isSignedIntegerType(),
957                            Field->getType().getCVRQualifiers()|CVRQualifiers);
958}
959
960LValue CodeGenFunction::EmitLValueForField(llvm::Value* BaseValue,
961                                           FieldDecl* Field,
962                                           bool isUnion,
963                                           unsigned CVRQualifiers)
964{
965  if (Field->isBitField())
966    return EmitLValueForBitfield(BaseValue, Field, CVRQualifiers);
967
968  unsigned idx = CGM.getTypes().getLLVMFieldNo(Field);
969  llvm::Value *V = Builder.CreateStructGEP(BaseValue, idx, "tmp");
970
971  // Match union field type.
972  if (isUnion) {
973    const llvm::Type *FieldTy =
974      CGM.getTypes().ConvertTypeForMem(Field->getType());
975    const llvm::PointerType * BaseTy =
976      cast<llvm::PointerType>(BaseValue->getType());
977    unsigned AS = BaseTy->getAddressSpace();
978    V = Builder.CreateBitCast(V,
979                              llvm::PointerType::get(FieldTy, AS),
980                              "tmp");
981  }
982
983  QualType::GCAttrTypes attr = QualType::GCNone;
984  if (CGM.getLangOptions().ObjC1 &&
985      CGM.getLangOptions().getGCMode() != LangOptions::NonGC) {
986    QualType Ty = Field->getType();
987    attr = Ty.getObjCGCAttr();
988    if (attr != QualType::GCNone) {
989      // __weak attribute on a field is ignored.
990      if (attr == QualType::Weak)
991        attr = QualType::GCNone;
992    }
993    else if (getContext().isObjCObjectPointerType(Ty))
994      attr = QualType::Strong;
995  }
996  LValue LV =
997    LValue::MakeAddr(V,
998                     Field->getType().getCVRQualifiers()|CVRQualifiers,
999                     attr);
1000  return LV;
1001}
1002
1003LValue CodeGenFunction::EmitCompoundLiteralLValue(const CompoundLiteralExpr* E){
1004  const llvm::Type *LTy = ConvertType(E->getType());
1005  llvm::Value *DeclPtr = CreateTempAlloca(LTy, ".compoundliteral");
1006
1007  const Expr* InitExpr = E->getInitializer();
1008  LValue Result = LValue::MakeAddr(DeclPtr, E->getType().getCVRQualifiers());
1009
1010  if (E->getType()->isComplexType()) {
1011    EmitComplexExprIntoAddr(InitExpr, DeclPtr, false);
1012  } else if (hasAggregateLLVMType(E->getType())) {
1013    EmitAnyExpr(InitExpr, DeclPtr, false);
1014  } else {
1015    EmitStoreThroughLValue(EmitAnyExpr(InitExpr), Result, E->getType());
1016  }
1017
1018  return Result;
1019}
1020
1021LValue CodeGenFunction::EmitConditionalOperator(const ConditionalOperator* E) {
1022  // We don't handle vectors yet.
1023  if (E->getType()->isVectorType())
1024    return EmitUnsupportedLValue(E, "conditional operator");
1025
1026  // ?: here should be an aggregate.
1027  assert((hasAggregateLLVMType(E->getType()) &&
1028          !E->getType()->isAnyComplexType()) &&
1029         "Unexpected conditional operator!");
1030
1031  llvm::Value *Temp = CreateTempAlloca(ConvertType(E->getType()));
1032  EmitAggExpr(E, Temp, false);
1033
1034  return LValue::MakeAddr(Temp, E->getType().getCVRQualifiers(),
1035                          getContext().getObjCGCAttrKind(E->getType()));
1036
1037}
1038
1039/// EmitCastLValue - Casts are never lvalues.  If a cast is needed by the code
1040/// generator in an lvalue context, then it must mean that we need the address
1041/// of an aggregate in order to access one of its fields.  This can happen for
1042/// all the reasons that casts are permitted with aggregate result, including
1043/// noop aggregate casts, and cast from scalar to union.
1044LValue CodeGenFunction::EmitCastLValue(const CastExpr *E) {
1045  // If this is an aggregate-to-aggregate cast, just use the input's address as
1046  // the lvalue.
1047  if (getContext().hasSameUnqualifiedType(E->getType(),
1048                                          E->getSubExpr()->getType()))
1049    return EmitLValue(E->getSubExpr());
1050
1051  // Otherwise, we must have a cast from scalar to union.
1052  assert(E->getType()->isUnionType() && "Expected scalar-to-union cast");
1053
1054  // Casts are only lvalues when the source and destination types are the same.
1055  llvm::Value *Temp = CreateTempAlloca(ConvertType(E->getType()));
1056  EmitAnyExpr(E->getSubExpr(), Temp, false);
1057
1058  return LValue::MakeAddr(Temp, E->getType().getCVRQualifiers(),
1059                          getContext().getObjCGCAttrKind(E->getType()));
1060}
1061
1062//===--------------------------------------------------------------------===//
1063//                             Expression Emission
1064//===--------------------------------------------------------------------===//
1065
1066
1067RValue CodeGenFunction::EmitCallExpr(const CallExpr *E) {
1068  // Builtins never have block type.
1069  if (E->getCallee()->getType()->isBlockPointerType())
1070    return EmitBlockCallExpr(E);
1071
1072  if (const CXXMemberCallExpr *CE = dyn_cast<CXXMemberCallExpr>(E))
1073    return EmitCXXMemberCallExpr(CE);
1074
1075  const Decl *TargetDecl = 0;
1076  if (const ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(E->getCallee())) {
1077    if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(CE->getSubExpr())) {
1078      TargetDecl = DRE->getDecl();
1079      if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(TargetDecl))
1080        if (unsigned builtinID = FD->getBuiltinID(getContext()))
1081          return EmitBuiltinExpr(FD, builtinID, E);
1082    }
1083  }
1084
1085  llvm::Value *Callee = EmitScalarExpr(E->getCallee());
1086  return EmitCallExpr(Callee, E->getCallee()->getType(),
1087                      E->arg_begin(), E->arg_end(), TargetDecl);
1088}
1089
1090LValue CodeGenFunction::EmitBinaryOperatorLValue(const BinaryOperator *E) {
1091  // Can only get l-value for binary operator expressions which are a
1092  // simple assignment of aggregate type.
1093  if (E->getOpcode() != BinaryOperator::Assign)
1094    return EmitUnsupportedLValue(E, "binary l-value expression");
1095
1096  llvm::Value *Temp = CreateTempAlloca(ConvertType(E->getType()));
1097  EmitAggExpr(E, Temp, false);
1098  // FIXME: Are these qualifiers correct?
1099  return LValue::MakeAddr(Temp, E->getType().getCVRQualifiers(),
1100                          getContext().getObjCGCAttrKind(E->getType()));
1101}
1102
1103LValue CodeGenFunction::EmitCallExprLValue(const CallExpr *E) {
1104  // Can only get l-value for call expression returning aggregate type
1105  RValue RV = EmitCallExpr(E);
1106  return LValue::MakeAddr(RV.getAggregateAddr(),
1107                          E->getType().getCVRQualifiers(),
1108                          getContext().getObjCGCAttrKind(E->getType()));
1109}
1110
1111LValue CodeGenFunction::EmitVAArgExprLValue(const VAArgExpr *E) {
1112  // FIXME: This shouldn't require another copy.
1113  llvm::Value *Temp = CreateTempAlloca(ConvertType(E->getType()));
1114  EmitAggExpr(E, Temp, false);
1115  return LValue::MakeAddr(Temp, E->getType().getCVRQualifiers());
1116}
1117
1118LValue
1119CodeGenFunction::EmitCXXConditionDeclLValue(const CXXConditionDeclExpr *E) {
1120  EmitLocalBlockVarDecl(*E->getVarDecl());
1121  return EmitDeclRefLValue(E);
1122}
1123
1124LValue CodeGenFunction::EmitObjCMessageExprLValue(const ObjCMessageExpr *E) {
1125  // Can only get l-value for message expression returning aggregate type
1126  RValue RV = EmitObjCMessageExpr(E);
1127  // FIXME: can this be volatile?
1128  return LValue::MakeAddr(RV.getAggregateAddr(),
1129                          E->getType().getCVRQualifiers(),
1130                          getContext().getObjCGCAttrKind(E->getType()));
1131}
1132
1133llvm::Value *CodeGenFunction::EmitIvarOffset(ObjCInterfaceDecl *Interface,
1134                                             const ObjCIvarDecl *Ivar) {
1135  // Objective-C objects are traditionally C structures with their layout
1136  // defined at compile-time.  In some implementations, their layout is not
1137  // defined until run time in order to allow instance variables to be added to
1138  // a class without recompiling all of the subclasses.  If this is the case
1139  // then the CGObjCRuntime subclass must return true to LateBoundIvars and
1140  // implement the lookup itself.
1141  if (CGM.getObjCRuntime().LateBoundIVars())
1142    assert(0 && "late-bound ivars are unsupported");
1143  return CGM.getObjCRuntime().EmitIvarOffset(*this, Interface, Ivar);
1144}
1145
1146LValue CodeGenFunction::EmitLValueForIvar(QualType ObjectTy,
1147                                          llvm::Value *BaseValue,
1148                                          const ObjCIvarDecl *Ivar,
1149                                          const FieldDecl *Field,
1150                                          unsigned CVRQualifiers) {
1151  // See comment in EmitIvarOffset.
1152  if (CGM.getObjCRuntime().LateBoundIVars())
1153    assert(0 && "late-bound ivars are unsupported");
1154
1155  LValue LV = CGM.getObjCRuntime().EmitObjCValueForIvar(*this,
1156                                                        ObjectTy,
1157                                                        BaseValue, Ivar, Field,
1158                                                        CVRQualifiers);
1159  return LV;
1160}
1161
1162LValue CodeGenFunction::EmitObjCIvarRefLValue(const ObjCIvarRefExpr *E) {
1163  // FIXME: A lot of the code below could be shared with EmitMemberExpr.
1164  llvm::Value *BaseValue = 0;
1165  const Expr *BaseExpr = E->getBase();
1166  unsigned CVRQualifiers = 0;
1167  QualType ObjectTy;
1168  if (E->isArrow()) {
1169    BaseValue = EmitScalarExpr(BaseExpr);
1170    const PointerType *PTy =
1171      cast<PointerType>(getContext().getCanonicalType(BaseExpr->getType()));
1172    ObjectTy = PTy->getPointeeType();
1173    CVRQualifiers = ObjectTy.getCVRQualifiers();
1174  } else {
1175    LValue BaseLV = EmitLValue(BaseExpr);
1176    // FIXME: this isn't right for bitfields.
1177    BaseValue = BaseLV.getAddress();
1178    ObjectTy = BaseExpr->getType();
1179    CVRQualifiers = ObjectTy.getCVRQualifiers();
1180  }
1181
1182  return EmitLValueForIvar(ObjectTy, BaseValue, E->getDecl(),
1183                           getContext().getFieldDecl(E), CVRQualifiers);
1184}
1185
1186LValue
1187CodeGenFunction::EmitObjCPropertyRefLValue(const ObjCPropertyRefExpr *E) {
1188  // This is a special l-value that just issues sends when we load or
1189  // store through it.
1190  return LValue::MakePropertyRef(E, E->getType().getCVRQualifiers());
1191}
1192
1193LValue
1194CodeGenFunction::EmitObjCKVCRefLValue(const ObjCKVCRefExpr *E) {
1195  // This is a special l-value that just issues sends when we load or
1196  // store through it.
1197  return LValue::MakeKVCRef(E, E->getType().getCVRQualifiers());
1198}
1199
1200LValue
1201CodeGenFunction::EmitObjCSuperExpr(const ObjCSuperExpr *E) {
1202  return EmitUnsupportedLValue(E, "use of super");
1203}
1204
1205RValue CodeGenFunction::EmitCallExpr(llvm::Value *Callee, QualType CalleeType,
1206                                     CallExpr::const_arg_iterator ArgBeg,
1207                                     CallExpr::const_arg_iterator ArgEnd,
1208                                     const Decl *TargetDecl) {
1209  // Get the actual function type. The callee type will always be a
1210  // pointer to function type or a block pointer type.
1211  assert(CalleeType->isFunctionPointerType() &&
1212         "Call must have function pointer type!");
1213
1214  QualType FnType = CalleeType->getAsPointerType()->getPointeeType();
1215  QualType ResultType = FnType->getAsFunctionType()->getResultType();
1216
1217  CallArgList Args;
1218  EmitCallArgs(Args, FnType->getAsFunctionProtoType(), ArgBeg, ArgEnd);
1219
1220  return EmitCall(CGM.getTypes().getFunctionInfo(ResultType, Args),
1221                  Callee, Args, TargetDecl);
1222}
1223