CGExpr.cpp revision 0979c805475d1ba49b5d6ef93c4d2ce6d2eab6ed 
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, bool IgnoreResult,
53                                    bool IsInitializer) {
54  if (!hasAggregateLLVMType(E->getType()))
55    return RValue::get(EmitScalarExpr(E, IgnoreResult));
56  else if (E->getType()->isAnyComplexType())
57    return RValue::getComplex(EmitComplexExpr(E, false, false,
58                                              IgnoreResult, IgnoreResult));
59
60  EmitAggExpr(E, AggLoc, IsAggLocVolatile, IgnoreResult, IsInitializer);
61  return RValue::getAggregate(AggLoc, IsAggLocVolatile);
62}
63
64/// EmitAnyExprToTemp - Similary to EmitAnyExpr(), however, the result
65/// will always be accessible even if no aggregate location is
66/// provided.
67RValue CodeGenFunction::EmitAnyExprToTemp(const Expr *E,
68                                          bool IsAggLocVolatile,
69                                          bool IsInitializer) {
70  llvm::Value *AggLoc = 0;
71
72  if (hasAggregateLLVMType(E->getType()) &&
73      !E->getType()->isAnyComplexType())
74    AggLoc = CreateTempAlloca(ConvertType(E->getType()), "agg.tmp");
75  return EmitAnyExpr(E, AggLoc, IsAggLocVolatile, /*IgnoreResult=*/false,
76                     IsInitializer);
77}
78
79RValue CodeGenFunction::EmitReferenceBindingToExpr(const Expr* E,
80                                                   QualType DestType,
81                                                   bool IsInitializer) {
82  RValue Val;
83  if (E->isLvalue(getContext()) == Expr::LV_Valid) {
84    // Emit the expr as an lvalue.
85    LValue LV = EmitLValue(E);
86    if (LV.isSimple())
87      return RValue::get(LV.getAddress());
88    Val = EmitLoadOfLValue(LV, E->getType());
89  } else {
90    // FIXME: Initializers don't work with casts yet. For example
91    // const A& a = B();
92    // if B inherits from A.
93    Val = EmitAnyExprToTemp(E, /*IsAggLocVolatile=*/false,
94                            IsInitializer);
95
96    if (IsInitializer) {
97      // We might have to destroy the temporary variable.
98      if (const RecordType *RT = E->getType()->getAs<RecordType>()) {
99        if (CXXRecordDecl *ClassDecl = dyn_cast<CXXRecordDecl>(RT->getDecl())) {
100          if (!ClassDecl->hasTrivialDestructor()) {
101            const CXXDestructorDecl *Dtor =
102              ClassDecl->getDestructor(getContext());
103
104            CleanupScope scope(*this);
105            EmitCXXDestructorCall(Dtor, Dtor_Complete, Val.getAggregateAddr());
106          }
107        }
108      }
109    }
110  }
111
112  if (Val.isAggregate()) {
113    Val = RValue::get(Val.getAggregateAddr());
114  } else {
115    // Create a temporary variable that we can bind the reference to.
116    llvm::Value *Temp = CreateTempAlloca(ConvertTypeForMem(E->getType()),
117                                         "reftmp");
118    if (Val.isScalar())
119      EmitStoreOfScalar(Val.getScalarVal(), Temp, false, E->getType());
120    else
121      StoreComplexToAddr(Val.getComplexVal(), Temp, false);
122    Val = RValue::get(Temp);
123  }
124
125  return Val;
126}
127
128
129/// getAccessedFieldNo - Given an encoded value and a result number, return
130/// the input field number being accessed.
131unsigned CodeGenFunction::getAccessedFieldNo(unsigned Idx,
132                                             const llvm::Constant *Elts) {
133  if (isa<llvm::ConstantAggregateZero>(Elts))
134    return 0;
135
136  return cast<llvm::ConstantInt>(Elts->getOperand(Idx))->getZExtValue();
137}
138
139
140//===----------------------------------------------------------------------===//
141//                         LValue Expression Emission
142//===----------------------------------------------------------------------===//
143
144RValue CodeGenFunction::GetUndefRValue(QualType Ty) {
145  if (Ty->isVoidType()) {
146    return RValue::get(0);
147  } else if (const ComplexType *CTy = Ty->getAsComplexType()) {
148    const llvm::Type *EltTy = ConvertType(CTy->getElementType());
149    llvm::Value *U = llvm::UndefValue::get(EltTy);
150    return RValue::getComplex(std::make_pair(U, U));
151  } else if (hasAggregateLLVMType(Ty)) {
152    const llvm::Type *LTy = llvm::PointerType::getUnqual(ConvertType(Ty));
153    return RValue::getAggregate(llvm::UndefValue::get(LTy));
154  } else {
155    return RValue::get(llvm::UndefValue::get(ConvertType(Ty)));
156  }
157}
158
159RValue CodeGenFunction::EmitUnsupportedRValue(const Expr *E,
160                                              const char *Name) {
161  ErrorUnsupported(E, Name);
162  return GetUndefRValue(E->getType());
163}
164
165LValue CodeGenFunction::EmitUnsupportedLValue(const Expr *E,
166                                              const char *Name) {
167  ErrorUnsupported(E, Name);
168  llvm::Type *Ty = llvm::PointerType::getUnqual(ConvertType(E->getType()));
169  return LValue::MakeAddr(llvm::UndefValue::get(Ty),
170                          E->getType().getCVRQualifiers(),
171                          getContext().getObjCGCAttrKind(E->getType()),
172                          E->getType().getAddressSpace());
173}
174
175/// EmitLValue - Emit code to compute a designator that specifies the location
176/// of the expression.
177///
178/// This can return one of two things: a simple address or a bitfield
179/// reference.  In either case, the LLVM Value* in the LValue structure is
180/// guaranteed to be an LLVM pointer type.
181///
182/// If this returns a bitfield reference, nothing about the pointee type of
183/// the LLVM value is known: For example, it may not be a pointer to an
184/// integer.
185///
186/// If this returns a normal address, and if the lvalue's C type is fixed
187/// size, this method guarantees that the returned pointer type will point to
188/// an LLVM type of the same size of the lvalue's type.  If the lvalue has a
189/// variable length type, this is not possible.
190///
191LValue CodeGenFunction::EmitLValue(const Expr *E) {
192  switch (E->getStmtClass()) {
193  default: return EmitUnsupportedLValue(E, "l-value expression");
194
195  case Expr::BinaryOperatorClass:
196    return EmitBinaryOperatorLValue(cast<BinaryOperator>(E));
197  case Expr::CallExprClass:
198  case Expr::CXXOperatorCallExprClass:
199    return EmitCallExprLValue(cast<CallExpr>(E));
200  case Expr::VAArgExprClass:
201    return EmitVAArgExprLValue(cast<VAArgExpr>(E));
202  case Expr::DeclRefExprClass:
203  case Expr::QualifiedDeclRefExprClass:
204    return EmitDeclRefLValue(cast<DeclRefExpr>(E));
205  case Expr::ParenExprClass:return EmitLValue(cast<ParenExpr>(E)->getSubExpr());
206  case Expr::PredefinedExprClass:
207    return EmitPredefinedLValue(cast<PredefinedExpr>(E));
208  case Expr::StringLiteralClass:
209    return EmitStringLiteralLValue(cast<StringLiteral>(E));
210  case Expr::ObjCEncodeExprClass:
211    return EmitObjCEncodeExprLValue(cast<ObjCEncodeExpr>(E));
212
213  case Expr::BlockDeclRefExprClass:
214    return EmitBlockDeclRefLValue(cast<BlockDeclRefExpr>(E));
215
216  case Expr::CXXConditionDeclExprClass:
217    return EmitCXXConditionDeclLValue(cast<CXXConditionDeclExpr>(E));
218  case Expr::CXXTemporaryObjectExprClass:
219  case Expr::CXXConstructExprClass:
220    return EmitCXXConstructLValue(cast<CXXConstructExpr>(E));
221  case Expr::CXXBindTemporaryExprClass:
222    return EmitCXXBindTemporaryLValue(cast<CXXBindTemporaryExpr>(E));
223
224  case Expr::ObjCMessageExprClass:
225    return EmitObjCMessageExprLValue(cast<ObjCMessageExpr>(E));
226  case Expr::ObjCIvarRefExprClass:
227    return EmitObjCIvarRefLValue(cast<ObjCIvarRefExpr>(E));
228  case Expr::ObjCPropertyRefExprClass:
229    return EmitObjCPropertyRefLValue(cast<ObjCPropertyRefExpr>(E));
230  case Expr::ObjCImplicitSetterGetterRefExprClass:
231    return EmitObjCKVCRefLValue(cast<ObjCImplicitSetterGetterRefExpr>(E));
232  case Expr::ObjCSuperExprClass:
233    return EmitObjCSuperExprLValue(cast<ObjCSuperExpr>(E));
234
235  case Expr::StmtExprClass:
236    return EmitStmtExprLValue(cast<StmtExpr>(E));
237  case Expr::UnaryOperatorClass:
238    return EmitUnaryOpLValue(cast<UnaryOperator>(E));
239  case Expr::ArraySubscriptExprClass:
240    return EmitArraySubscriptExpr(cast<ArraySubscriptExpr>(E));
241  case Expr::ExtVectorElementExprClass:
242    return EmitExtVectorElementExpr(cast<ExtVectorElementExpr>(E));
243  case Expr::MemberExprClass:
244  case Stmt::CXXAdornedMemberExprClass:
245    return EmitMemberExpr(cast<MemberExpr>(E));
246  case Expr::CompoundLiteralExprClass:
247    return EmitCompoundLiteralLValue(cast<CompoundLiteralExpr>(E));
248  case Expr::ConditionalOperatorClass:
249    return EmitConditionalOperator(cast<ConditionalOperator>(E));
250  case Expr::ChooseExprClass:
251    return EmitLValue(cast<ChooseExpr>(E)->getChosenSubExpr(getContext()));
252  case Expr::ImplicitCastExprClass:
253  case Expr::CStyleCastExprClass:
254  case Expr::CXXFunctionalCastExprClass:
255  case Expr::CXXStaticCastExprClass:
256  case Expr::CXXDynamicCastExprClass:
257  case Expr::CXXReinterpretCastExprClass:
258  case Expr::CXXConstCastExprClass:
259    return EmitCastLValue(cast<CastExpr>(E));
260  }
261}
262
263llvm::Value *CodeGenFunction::EmitLoadOfScalar(llvm::Value *Addr, bool Volatile,
264                                               QualType Ty) {
265  llvm::Value *V = Builder.CreateLoad(Addr, Volatile, "tmp");
266
267  // Bool can have different representation in memory than in registers.
268  if (Ty->isBooleanType())
269    if (V->getType() != llvm::Type::getInt1Ty(VMContext))
270      V = Builder.CreateTrunc(V, llvm::Type::getInt1Ty(VMContext), "tobool");
271
272  return V;
273}
274
275void CodeGenFunction::EmitStoreOfScalar(llvm::Value *Value, llvm::Value *Addr,
276                                        bool Volatile, QualType Ty) {
277
278  if (Ty->isBooleanType()) {
279    // Bool can have different representation in memory than in registers.
280    const llvm::Type *SrcTy = Value->getType();
281    const llvm::PointerType *DstPtr = cast<llvm::PointerType>(Addr->getType());
282    if (DstPtr->getElementType() != SrcTy) {
283      const llvm::Type *MemTy =
284        llvm::PointerType::get(SrcTy, DstPtr->getAddressSpace());
285      Addr = Builder.CreateBitCast(Addr, MemTy, "storetmp");
286    }
287  }
288  Builder.CreateStore(Value, Addr, Volatile);
289}
290
291/// EmitLoadOfLValue - Given an expression that represents a value lvalue,
292/// this method emits the address of the lvalue, then loads the result as an
293/// rvalue, returning the rvalue.
294RValue CodeGenFunction::EmitLoadOfLValue(LValue LV, QualType ExprType) {
295  if (LV.isObjCWeak()) {
296    // load of a __weak object.
297    llvm::Value *AddrWeakObj = LV.getAddress();
298    llvm::Value *read_weak = CGM.getObjCRuntime().EmitObjCWeakRead(*this,
299                                                                   AddrWeakObj);
300    return RValue::get(read_weak);
301  }
302
303  if (LV.isSimple()) {
304    llvm::Value *Ptr = LV.getAddress();
305    const llvm::Type *EltTy =
306      cast<llvm::PointerType>(Ptr->getType())->getElementType();
307
308    // Simple scalar l-value.
309    if (EltTy->isSingleValueType())
310      return RValue::get(EmitLoadOfScalar(Ptr, LV.isVolatileQualified(),
311                                          ExprType));
312
313    assert(ExprType->isFunctionType() && "Unknown scalar value");
314    return RValue::get(Ptr);
315  }
316
317  if (LV.isVectorElt()) {
318    llvm::Value *Vec = Builder.CreateLoad(LV.getVectorAddr(),
319                                          LV.isVolatileQualified(), "tmp");
320    return RValue::get(Builder.CreateExtractElement(Vec, LV.getVectorIdx(),
321                                                    "vecext"));
322  }
323
324  // If this is a reference to a subset of the elements of a vector, either
325  // shuffle the input or extract/insert them as appropriate.
326  if (LV.isExtVectorElt())
327    return EmitLoadOfExtVectorElementLValue(LV, ExprType);
328
329  if (LV.isBitfield())
330    return EmitLoadOfBitfieldLValue(LV, ExprType);
331
332  if (LV.isPropertyRef())
333    return EmitLoadOfPropertyRefLValue(LV, ExprType);
334
335  assert(LV.isKVCRef() && "Unknown LValue type!");
336  return EmitLoadOfKVCRefLValue(LV, ExprType);
337}
338
339RValue CodeGenFunction::EmitLoadOfBitfieldLValue(LValue LV,
340                                                 QualType ExprType) {
341  unsigned StartBit = LV.getBitfieldStartBit();
342  unsigned BitfieldSize = LV.getBitfieldSize();
343  llvm::Value *Ptr = LV.getBitfieldAddr();
344
345  const llvm::Type *EltTy =
346    cast<llvm::PointerType>(Ptr->getType())->getElementType();
347  unsigned EltTySize = CGM.getTargetData().getTypeSizeInBits(EltTy);
348
349  // In some cases the bitfield may straddle two memory locations.
350  // Currently we load the entire bitfield, then do the magic to
351  // sign-extend it if necessary. This results in somewhat more code
352  // than necessary for the common case (one load), since two shifts
353  // accomplish both the masking and sign extension.
354  unsigned LowBits = std::min(BitfieldSize, EltTySize - StartBit);
355  llvm::Value *Val = Builder.CreateLoad(Ptr, LV.isVolatileQualified(), "tmp");
356
357  // Shift to proper location.
358  if (StartBit)
359    Val = Builder.CreateLShr(Val, llvm::ConstantInt::get(EltTy, StartBit),
360                             "bf.lo");
361
362  // Mask off unused bits.
363  llvm::Constant *LowMask = llvm::ConstantInt::get(VMContext,
364                                llvm::APInt::getLowBitsSet(EltTySize, LowBits));
365  Val = Builder.CreateAnd(Val, LowMask, "bf.lo.cleared");
366
367  // Fetch the high bits if necessary.
368  if (LowBits < BitfieldSize) {
369    unsigned HighBits = BitfieldSize - LowBits;
370    llvm::Value *HighPtr = Builder.CreateGEP(Ptr, llvm::ConstantInt::get(
371                            llvm::Type::getInt32Ty(VMContext), 1), "bf.ptr.hi");
372    llvm::Value *HighVal = Builder.CreateLoad(HighPtr,
373                                              LV.isVolatileQualified(),
374                                              "tmp");
375
376    // Mask off unused bits.
377    llvm::Constant *HighMask = llvm::ConstantInt::get(VMContext,
378                               llvm::APInt::getLowBitsSet(EltTySize, HighBits));
379    HighVal = Builder.CreateAnd(HighVal, HighMask, "bf.lo.cleared");
380
381    // Shift to proper location and or in to bitfield value.
382    HighVal = Builder.CreateShl(HighVal,
383                                llvm::ConstantInt::get(EltTy, LowBits));
384    Val = Builder.CreateOr(Val, HighVal, "bf.val");
385  }
386
387  // Sign extend if necessary.
388  if (LV.isBitfieldSigned()) {
389    llvm::Value *ExtraBits = llvm::ConstantInt::get(EltTy,
390                                                    EltTySize - BitfieldSize);
391    Val = Builder.CreateAShr(Builder.CreateShl(Val, ExtraBits),
392                             ExtraBits, "bf.val.sext");
393  }
394
395  // The bitfield type and the normal type differ when the storage sizes
396  // differ (currently just _Bool).
397  Val = Builder.CreateIntCast(Val, ConvertType(ExprType), false, "tmp");
398
399  return RValue::get(Val);
400}
401
402RValue CodeGenFunction::EmitLoadOfPropertyRefLValue(LValue LV,
403                                                    QualType ExprType) {
404  return EmitObjCPropertyGet(LV.getPropertyRefExpr());
405}
406
407RValue CodeGenFunction::EmitLoadOfKVCRefLValue(LValue LV,
408                                               QualType ExprType) {
409  return EmitObjCPropertyGet(LV.getKVCRefExpr());
410}
411
412// If this is a reference to a subset of the elements of a vector, create an
413// appropriate shufflevector.
414RValue CodeGenFunction::EmitLoadOfExtVectorElementLValue(LValue LV,
415                                                         QualType ExprType) {
416  llvm::Value *Vec = Builder.CreateLoad(LV.getExtVectorAddr(),
417                                        LV.isVolatileQualified(), "tmp");
418
419  const llvm::Constant *Elts = LV.getExtVectorElts();
420
421  // If the result of the expression is a non-vector type, we must be
422  // extracting a single element.  Just codegen as an extractelement.
423  const VectorType *ExprVT = ExprType->getAsVectorType();
424  if (!ExprVT) {
425    unsigned InIdx = getAccessedFieldNo(0, Elts);
426    llvm::Value *Elt = llvm::ConstantInt::get(
427                                      llvm::Type::getInt32Ty(VMContext), InIdx);
428    return RValue::get(Builder.CreateExtractElement(Vec, Elt, "tmp"));
429  }
430
431  // Always use shuffle vector to try to retain the original program structure
432  unsigned NumResultElts = ExprVT->getNumElements();
433
434  llvm::SmallVector<llvm::Constant*, 4> Mask;
435  for (unsigned i = 0; i != NumResultElts; ++i) {
436    unsigned InIdx = getAccessedFieldNo(i, Elts);
437    Mask.push_back(llvm::ConstantInt::get(
438                                     llvm::Type::getInt32Ty(VMContext), InIdx));
439  }
440
441  llvm::Value *MaskV = llvm::ConstantVector::get(&Mask[0], Mask.size());
442  Vec = Builder.CreateShuffleVector(Vec,
443                                    llvm::UndefValue::get(Vec->getType()),
444                                    MaskV, "tmp");
445  return RValue::get(Vec);
446}
447
448
449
450/// EmitStoreThroughLValue - Store the specified rvalue into the specified
451/// lvalue, where both are guaranteed to the have the same type, and that type
452/// is 'Ty'.
453void CodeGenFunction::EmitStoreThroughLValue(RValue Src, LValue Dst,
454                                             QualType Ty) {
455  if (!Dst.isSimple()) {
456    if (Dst.isVectorElt()) {
457      // Read/modify/write the vector, inserting the new element.
458      llvm::Value *Vec = Builder.CreateLoad(Dst.getVectorAddr(),
459                                            Dst.isVolatileQualified(), "tmp");
460      Vec = Builder.CreateInsertElement(Vec, Src.getScalarVal(),
461                                        Dst.getVectorIdx(), "vecins");
462      Builder.CreateStore(Vec, Dst.getVectorAddr(),Dst.isVolatileQualified());
463      return;
464    }
465
466    // If this is an update of extended vector elements, insert them as
467    // appropriate.
468    if (Dst.isExtVectorElt())
469      return EmitStoreThroughExtVectorComponentLValue(Src, Dst, Ty);
470
471    if (Dst.isBitfield())
472      return EmitStoreThroughBitfieldLValue(Src, Dst, Ty);
473
474    if (Dst.isPropertyRef())
475      return EmitStoreThroughPropertyRefLValue(Src, Dst, Ty);
476
477    if (Dst.isKVCRef())
478      return EmitStoreThroughKVCRefLValue(Src, Dst, Ty);
479
480    assert(0 && "Unknown LValue type");
481  }
482
483  if (Dst.isObjCWeak() && !Dst.isNonGC()) {
484    // load of a __weak object.
485    llvm::Value *LvalueDst = Dst.getAddress();
486    llvm::Value *src = Src.getScalarVal();
487     CGM.getObjCRuntime().EmitObjCWeakAssign(*this, src, LvalueDst);
488    return;
489  }
490
491  if (Dst.isObjCStrong() && !Dst.isNonGC()) {
492    // load of a __strong object.
493    llvm::Value *LvalueDst = Dst.getAddress();
494    llvm::Value *src = Src.getScalarVal();
495#if 0
496    // FIXME. We cannot positively determine if we have an 'ivar' assignment,
497    // object assignment or an unknown assignment. For now, generate call to
498    // objc_assign_strongCast assignment which is a safe, but consevative
499    // assumption.
500    if (Dst.isObjCIvar())
501      CGM.getObjCRuntime().EmitObjCIvarAssign(*this, src, LvalueDst);
502    else
503      CGM.getObjCRuntime().EmitObjCGlobalAssign(*this, src, LvalueDst);
504#endif
505    if (Dst.isGlobalObjCRef())
506      CGM.getObjCRuntime().EmitObjCGlobalAssign(*this, src, LvalueDst);
507    else
508      CGM.getObjCRuntime().EmitObjCStrongCastAssign(*this, src, LvalueDst);
509    return;
510  }
511
512  assert(Src.isScalar() && "Can't emit an agg store with this method");
513  EmitStoreOfScalar(Src.getScalarVal(), Dst.getAddress(),
514                    Dst.isVolatileQualified(), Ty);
515}
516
517void CodeGenFunction::EmitStoreThroughBitfieldLValue(RValue Src, LValue Dst,
518                                                     QualType Ty,
519                                                     llvm::Value **Result) {
520  unsigned StartBit = Dst.getBitfieldStartBit();
521  unsigned BitfieldSize = Dst.getBitfieldSize();
522  llvm::Value *Ptr = Dst.getBitfieldAddr();
523
524  const llvm::Type *EltTy =
525    cast<llvm::PointerType>(Ptr->getType())->getElementType();
526  unsigned EltTySize = CGM.getTargetData().getTypeSizeInBits(EltTy);
527
528  // Get the new value, cast to the appropriate type and masked to
529  // exactly the size of the bit-field.
530  llvm::Value *SrcVal = Src.getScalarVal();
531  llvm::Value *NewVal = Builder.CreateIntCast(SrcVal, EltTy, false, "tmp");
532  llvm::Constant *Mask = llvm::ConstantInt::get(VMContext,
533                           llvm::APInt::getLowBitsSet(EltTySize, BitfieldSize));
534  NewVal = Builder.CreateAnd(NewVal, Mask, "bf.value");
535
536  // Return the new value of the bit-field, if requested.
537  if (Result) {
538    // Cast back to the proper type for result.
539    const llvm::Type *SrcTy = SrcVal->getType();
540    llvm::Value *SrcTrunc = Builder.CreateIntCast(NewVal, SrcTy, false,
541                                                  "bf.reload.val");
542
543    // Sign extend if necessary.
544    if (Dst.isBitfieldSigned()) {
545      unsigned SrcTySize = CGM.getTargetData().getTypeSizeInBits(SrcTy);
546      llvm::Value *ExtraBits = llvm::ConstantInt::get(SrcTy,
547                                                      SrcTySize - BitfieldSize);
548      SrcTrunc = Builder.CreateAShr(Builder.CreateShl(SrcTrunc, ExtraBits),
549                                    ExtraBits, "bf.reload.sext");
550    }
551
552    *Result = SrcTrunc;
553  }
554
555  // In some cases the bitfield may straddle two memory locations.
556  // Emit the low part first and check to see if the high needs to be
557  // done.
558  unsigned LowBits = std::min(BitfieldSize, EltTySize - StartBit);
559  llvm::Value *LowVal = Builder.CreateLoad(Ptr, Dst.isVolatileQualified(),
560                                           "bf.prev.low");
561
562  // Compute the mask for zero-ing the low part of this bitfield.
563  llvm::Constant *InvMask =
564    llvm::ConstantInt::get(VMContext,
565             ~llvm::APInt::getBitsSet(EltTySize, StartBit, StartBit + LowBits));
566
567  // Compute the new low part as
568  //   LowVal = (LowVal & InvMask) | (NewVal << StartBit),
569  // with the shift of NewVal implicitly stripping the high bits.
570  llvm::Value *NewLowVal =
571    Builder.CreateShl(NewVal, llvm::ConstantInt::get(EltTy, StartBit),
572                      "bf.value.lo");
573  LowVal = Builder.CreateAnd(LowVal, InvMask, "bf.prev.lo.cleared");
574  LowVal = Builder.CreateOr(LowVal, NewLowVal, "bf.new.lo");
575
576  // Write back.
577  Builder.CreateStore(LowVal, Ptr, Dst.isVolatileQualified());
578
579  // If the low part doesn't cover the bitfield emit a high part.
580  if (LowBits < BitfieldSize) {
581    unsigned HighBits = BitfieldSize - LowBits;
582    llvm::Value *HighPtr =  Builder.CreateGEP(Ptr, llvm::ConstantInt::get(
583                            llvm::Type::getInt32Ty(VMContext), 1), "bf.ptr.hi");
584    llvm::Value *HighVal = Builder.CreateLoad(HighPtr,
585                                              Dst.isVolatileQualified(),
586                                              "bf.prev.hi");
587
588    // Compute the mask for zero-ing the high part of this bitfield.
589    llvm::Constant *InvMask =
590      llvm::ConstantInt::get(VMContext, ~llvm::APInt::getLowBitsSet(EltTySize,
591                               HighBits));
592
593    // Compute the new high part as
594    //   HighVal = (HighVal & InvMask) | (NewVal lshr LowBits),
595    // where the high bits of NewVal have already been cleared and the
596    // shift stripping the low bits.
597    llvm::Value *NewHighVal =
598      Builder.CreateLShr(NewVal, llvm::ConstantInt::get(EltTy, LowBits),
599                        "bf.value.high");
600    HighVal = Builder.CreateAnd(HighVal, InvMask, "bf.prev.hi.cleared");
601    HighVal = Builder.CreateOr(HighVal, NewHighVal, "bf.new.hi");
602
603    // Write back.
604    Builder.CreateStore(HighVal, HighPtr, Dst.isVolatileQualified());
605  }
606}
607
608void CodeGenFunction::EmitStoreThroughPropertyRefLValue(RValue Src,
609                                                        LValue Dst,
610                                                        QualType Ty) {
611  EmitObjCPropertySet(Dst.getPropertyRefExpr(), Src);
612}
613
614void CodeGenFunction::EmitStoreThroughKVCRefLValue(RValue Src,
615                                                   LValue Dst,
616                                                   QualType Ty) {
617  EmitObjCPropertySet(Dst.getKVCRefExpr(), Src);
618}
619
620void CodeGenFunction::EmitStoreThroughExtVectorComponentLValue(RValue Src,
621                                                               LValue Dst,
622                                                               QualType Ty) {
623  // This access turns into a read/modify/write of the vector.  Load the input
624  // value now.
625  llvm::Value *Vec = Builder.CreateLoad(Dst.getExtVectorAddr(),
626                                        Dst.isVolatileQualified(), "tmp");
627  const llvm::Constant *Elts = Dst.getExtVectorElts();
628
629  llvm::Value *SrcVal = Src.getScalarVal();
630
631  if (const VectorType *VTy = Ty->getAsVectorType()) {
632    unsigned NumSrcElts = VTy->getNumElements();
633    unsigned NumDstElts =
634       cast<llvm::VectorType>(Vec->getType())->getNumElements();
635    if (NumDstElts == NumSrcElts) {
636      // Use shuffle vector is the src and destination are the same number
637      // of elements and restore the vector mask since it is on the side
638      // it will be stored.
639      llvm::SmallVector<llvm::Constant*, 4> Mask(NumDstElts);
640      for (unsigned i = 0; i != NumSrcElts; ++i) {
641        unsigned InIdx = getAccessedFieldNo(i, Elts);
642        Mask[InIdx] = llvm::ConstantInt::get(
643                                          llvm::Type::getInt32Ty(VMContext), i);
644      }
645
646      llvm::Value *MaskV = llvm::ConstantVector::get(&Mask[0], Mask.size());
647      Vec = Builder.CreateShuffleVector(SrcVal,
648                                        llvm::UndefValue::get(Vec->getType()),
649                                        MaskV, "tmp");
650    } else if (NumDstElts > NumSrcElts) {
651      // Extended the source vector to the same length and then shuffle it
652      // into the destination.
653      // FIXME: since we're shuffling with undef, can we just use the indices
654      //        into that?  This could be simpler.
655      llvm::SmallVector<llvm::Constant*, 4> ExtMask;
656      unsigned i;
657      for (i = 0; i != NumSrcElts; ++i)
658        ExtMask.push_back(llvm::ConstantInt::get(
659                                         llvm::Type::getInt32Ty(VMContext), i));
660      for (; i != NumDstElts; ++i)
661        ExtMask.push_back(llvm::UndefValue::get(
662                                            llvm::Type::getInt32Ty(VMContext)));
663      llvm::Value *ExtMaskV = llvm::ConstantVector::get(&ExtMask[0],
664                                                        ExtMask.size());
665      llvm::Value *ExtSrcVal =
666        Builder.CreateShuffleVector(SrcVal,
667                                    llvm::UndefValue::get(SrcVal->getType()),
668                                    ExtMaskV, "tmp");
669      // build identity
670      llvm::SmallVector<llvm::Constant*, 4> Mask;
671      for (unsigned i = 0; i != NumDstElts; ++i) {
672        Mask.push_back(llvm::ConstantInt::get(
673                                        llvm::Type::getInt32Ty(VMContext), i));
674      }
675      // modify when what gets shuffled in
676      for (unsigned i = 0; i != NumSrcElts; ++i) {
677        unsigned Idx = getAccessedFieldNo(i, Elts);
678        Mask[Idx] = llvm::ConstantInt::get(
679                               llvm::Type::getInt32Ty(VMContext), i+NumDstElts);
680      }
681      llvm::Value *MaskV = llvm::ConstantVector::get(&Mask[0], Mask.size());
682      Vec = Builder.CreateShuffleVector(Vec, ExtSrcVal, MaskV, "tmp");
683    } else {
684      // We should never shorten the vector
685      assert(0 && "unexpected shorten vector length");
686    }
687  } else {
688    // If the Src is a scalar (not a vector) it must be updating one element.
689    unsigned InIdx = getAccessedFieldNo(0, Elts);
690    llvm::Value *Elt = llvm::ConstantInt::get(
691                                      llvm::Type::getInt32Ty(VMContext), InIdx);
692    Vec = Builder.CreateInsertElement(Vec, SrcVal, Elt, "tmp");
693  }
694
695  Builder.CreateStore(Vec, Dst.getExtVectorAddr(), Dst.isVolatileQualified());
696}
697
698LValue CodeGenFunction::EmitDeclRefLValue(const DeclRefExpr *E) {
699  const VarDecl *VD = dyn_cast<VarDecl>(E->getDecl());
700
701  if (VD && (VD->isBlockVarDecl() || isa<ParmVarDecl>(VD) ||
702        isa<ImplicitParamDecl>(VD))) {
703    LValue LV;
704    bool NonGCable = VD->hasLocalStorage() &&
705      !VD->hasAttr<BlocksAttr>();
706    if (VD->hasExternalStorage()) {
707      llvm::Value *V = CGM.GetAddrOfGlobalVar(VD);
708      if (VD->getType()->isReferenceType())
709        V = Builder.CreateLoad(V, "tmp");
710      LV = LValue::MakeAddr(V, E->getType().getCVRQualifiers(),
711                            getContext().getObjCGCAttrKind(E->getType()),
712                            E->getType().getAddressSpace());
713    } else {
714      llvm::Value *V = LocalDeclMap[VD];
715      assert(V && "DeclRefExpr not entered in LocalDeclMap?");
716      // local variables do not get their gc attribute set.
717      QualType::GCAttrTypes attr = QualType::GCNone;
718      // local static?
719      if (!NonGCable)
720        attr = getContext().getObjCGCAttrKind(E->getType());
721      if (VD->hasAttr<BlocksAttr>()) {
722        bool needsCopyDispose = BlockRequiresCopying(VD->getType());
723        const llvm::Type *PtrStructTy = V->getType();
724        const llvm::Type *Ty = PtrStructTy;
725        Ty = llvm::PointerType::get(Ty, 0);
726        V = Builder.CreateStructGEP(V, 1, "forwarding");
727        V = Builder.CreateBitCast(V, Ty);
728        V = Builder.CreateLoad(V, false);
729        V = Builder.CreateBitCast(V, PtrStructTy);
730        V = Builder.CreateStructGEP(V, needsCopyDispose*2 + 4, "x");
731      }
732      if (VD->getType()->isReferenceType())
733        V = Builder.CreateLoad(V, "tmp");
734      LV = LValue::MakeAddr(V, E->getType().getCVRQualifiers(), attr,
735                            E->getType().getAddressSpace());
736    }
737    LValue::SetObjCNonGC(LV, NonGCable);
738    return LV;
739  } else if (VD && VD->isFileVarDecl()) {
740    llvm::Value *V = CGM.GetAddrOfGlobalVar(VD);
741    if (VD->getType()->isReferenceType())
742      V = Builder.CreateLoad(V, "tmp");
743    LValue LV = LValue::MakeAddr(V, E->getType().getCVRQualifiers(),
744                                 getContext().getObjCGCAttrKind(E->getType()),
745                                 E->getType().getAddressSpace());
746    if (LV.isObjCStrong())
747      LV.SetGlobalObjCRef(LV, true);
748    return LV;
749  } else if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(E->getDecl())) {
750    llvm::Value* V = CGM.GetAddrOfFunction(GlobalDecl(FD));
751    if (!FD->hasPrototype()) {
752      if (const FunctionProtoType *Proto =
753              FD->getType()->getAsFunctionProtoType()) {
754        // Ugly case: for a K&R-style definition, the type of the definition
755        // isn't the same as the type of a use.  Correct for this with a
756        // bitcast.
757        QualType NoProtoType =
758            getContext().getFunctionNoProtoType(Proto->getResultType());
759        NoProtoType = getContext().getPointerType(NoProtoType);
760        V = Builder.CreateBitCast(V, ConvertType(NoProtoType), "tmp");
761      }
762    }
763    return LValue::MakeAddr(V, E->getType().getCVRQualifiers(),
764                            getContext().getObjCGCAttrKind(E->getType()),
765                            E->getType().getAddressSpace());
766  } else if (const ImplicitParamDecl *IPD =
767      dyn_cast<ImplicitParamDecl>(E->getDecl())) {
768    llvm::Value *V = LocalDeclMap[IPD];
769    assert(V && "BlockVarDecl not entered in LocalDeclMap?");
770    return LValue::MakeAddr(V, E->getType().getCVRQualifiers(),
771                            getContext().getObjCGCAttrKind(E->getType()),
772                            E->getType().getAddressSpace());
773  }
774  assert(0 && "Unimp declref");
775  //an invalid LValue, but the assert will
776  //ensure that this point is never reached.
777  return LValue();
778}
779
780LValue CodeGenFunction::EmitBlockDeclRefLValue(const BlockDeclRefExpr *E) {
781  return LValue::MakeAddr(GetAddrOfBlockDecl(E),
782                          E->getType().getCVRQualifiers(),
783                          getContext().getObjCGCAttrKind(E->getType()),
784                          E->getType().getAddressSpace());
785}
786
787LValue CodeGenFunction::EmitUnaryOpLValue(const UnaryOperator *E) {
788  // __extension__ doesn't affect lvalue-ness.
789  if (E->getOpcode() == UnaryOperator::Extension)
790    return EmitLValue(E->getSubExpr());
791
792  QualType ExprTy = getContext().getCanonicalType(E->getSubExpr()->getType());
793  switch (E->getOpcode()) {
794  default: assert(0 && "Unknown unary operator lvalue!");
795  case UnaryOperator::Deref:
796    {
797      QualType T = E->getSubExpr()->getType()->getPointeeType();
798      assert(!T.isNull() && "CodeGenFunction::EmitUnaryOpLValue: Illegal type");
799
800      LValue LV = LValue::MakeAddr(EmitScalarExpr(E->getSubExpr()),
801                                   T.getCVRQualifiers(),
802                                   getContext().getObjCGCAttrKind(T),
803                                   ExprTy.getAddressSpace());
804     // We should not generate __weak write barrier on indirect reference
805     // of a pointer to object; as in void foo (__weak id *param); *param = 0;
806     // But, we continue to generate __strong write barrier on indirect write
807     // into a pointer to object.
808     if (getContext().getLangOptions().ObjC1 &&
809         getContext().getLangOptions().getGCMode() != LangOptions::NonGC &&
810         LV.isObjCWeak())
811       LValue::SetObjCNonGC(LV, !E->isOBJCGCCandidate(getContext()));
812     return LV;
813    }
814  case UnaryOperator::Real:
815  case UnaryOperator::Imag:
816    LValue LV = EmitLValue(E->getSubExpr());
817    unsigned Idx = E->getOpcode() == UnaryOperator::Imag;
818    return LValue::MakeAddr(Builder.CreateStructGEP(LV.getAddress(),
819                                                    Idx, "idx"),
820                            ExprTy.getCVRQualifiers(),
821                            QualType::GCNone,
822                            ExprTy.getAddressSpace());
823  }
824}
825
826LValue CodeGenFunction::EmitStringLiteralLValue(const StringLiteral *E) {
827  return LValue::MakeAddr(CGM.GetAddrOfConstantStringFromLiteral(E), 0);
828}
829
830LValue CodeGenFunction::EmitObjCEncodeExprLValue(const ObjCEncodeExpr *E) {
831  return LValue::MakeAddr(CGM.GetAddrOfConstantStringFromObjCEncode(E), 0);
832}
833
834
835LValue CodeGenFunction::EmitPredefinedFunctionName(unsigned Type) {
836  std::string GlobalVarName;
837
838  switch (Type) {
839  default:
840    assert(0 && "Invalid type");
841  case PredefinedExpr::Func:
842    GlobalVarName = "__func__.";
843    break;
844  case PredefinedExpr::Function:
845    GlobalVarName = "__FUNCTION__.";
846    break;
847  case PredefinedExpr::PrettyFunction:
848    // FIXME:: Demangle C++ method names
849    GlobalVarName = "__PRETTY_FUNCTION__.";
850    break;
851  }
852
853  // FIXME: This isn't right at all.  The logic for computing this should go
854  // into a method on PredefinedExpr.  This would allow sema and codegen to be
855  // consistent for things like sizeof(__func__) etc.
856  std::string FunctionName;
857  if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(CurCodeDecl)) {
858    FunctionName = CGM.getMangledName(FD);
859  } else {
860    // Just get the mangled name; skipping the asm prefix if it
861    // exists.
862    FunctionName = CurFn->getName();
863    if (FunctionName[0] == '\01')
864      FunctionName = FunctionName.substr(1, std::string::npos);
865  }
866
867  GlobalVarName += FunctionName;
868  llvm::Constant *C =
869    CGM.GetAddrOfConstantCString(FunctionName, GlobalVarName.c_str());
870  return LValue::MakeAddr(C, 0);
871}
872
873LValue CodeGenFunction::EmitPredefinedLValue(const PredefinedExpr *E) {
874  switch (E->getIdentType()) {
875  default:
876    return EmitUnsupportedLValue(E, "predefined expression");
877  case PredefinedExpr::Func:
878  case PredefinedExpr::Function:
879  case PredefinedExpr::PrettyFunction:
880    return EmitPredefinedFunctionName(E->getIdentType());
881  }
882}
883
884LValue CodeGenFunction::EmitArraySubscriptExpr(const ArraySubscriptExpr *E) {
885  // The index must always be an integer, which is not an aggregate.  Emit it.
886  llvm::Value *Idx = EmitScalarExpr(E->getIdx());
887  QualType IdxTy  = E->getIdx()->getType();
888  bool IdxSigned = IdxTy->isSignedIntegerType();
889
890  // If the base is a vector type, then we are forming a vector element lvalue
891  // with this subscript.
892  if (E->getBase()->getType()->isVectorType()) {
893    // Emit the vector as an lvalue to get its address.
894    LValue LHS = EmitLValue(E->getBase());
895    assert(LHS.isSimple() && "Can only subscript lvalue vectors here!");
896    Idx = Builder.CreateIntCast(Idx,
897                          llvm::Type::getInt32Ty(VMContext), IdxSigned, "vidx");
898    return LValue::MakeVectorElt(LHS.getAddress(), Idx,
899      E->getBase()->getType().getCVRQualifiers());
900  }
901
902  // The base must be a pointer, which is not an aggregate.  Emit it.
903  llvm::Value *Base = EmitScalarExpr(E->getBase());
904
905  // Extend or truncate the index type to 32 or 64-bits.
906  unsigned IdxBitwidth = cast<llvm::IntegerType>(Idx->getType())->getBitWidth();
907  if (IdxBitwidth != LLVMPointerWidth)
908    Idx = Builder.CreateIntCast(Idx,
909                            llvm::IntegerType::get(VMContext, LLVMPointerWidth),
910                                IdxSigned, "idxprom");
911
912  // We know that the pointer points to a type of the correct size,
913  // unless the size is a VLA or Objective-C interface.
914  llvm::Value *Address = 0;
915  if (const VariableArrayType *VAT =
916        getContext().getAsVariableArrayType(E->getType())) {
917    llvm::Value *VLASize = GetVLASize(VAT);
918
919    Idx = Builder.CreateMul(Idx, VLASize);
920
921    QualType BaseType = getContext().getBaseElementType(VAT);
922
923    uint64_t BaseTypeSize = getContext().getTypeSize(BaseType) / 8;
924    Idx = Builder.CreateUDiv(Idx,
925                             llvm::ConstantInt::get(Idx->getType(),
926                                                    BaseTypeSize));
927    Address = Builder.CreateInBoundsGEP(Base, Idx, "arrayidx");
928  } else if (const ObjCInterfaceType *OIT =
929             dyn_cast<ObjCInterfaceType>(E->getType())) {
930    llvm::Value *InterfaceSize =
931      llvm::ConstantInt::get(Idx->getType(),
932                             getContext().getTypeSize(OIT) / 8);
933
934    Idx = Builder.CreateMul(Idx, InterfaceSize);
935
936    llvm::Type *i8PTy =
937            llvm::PointerType::getUnqual(llvm::Type::getInt8Ty(VMContext));
938    Address = Builder.CreateGEP(Builder.CreateBitCast(Base, i8PTy),
939                                Idx, "arrayidx");
940    Address = Builder.CreateBitCast(Address, Base->getType());
941  } else {
942    Address = Builder.CreateInBoundsGEP(Base, Idx, "arrayidx");
943  }
944
945  QualType T = E->getBase()->getType()->getPointeeType();
946  assert(!T.isNull() &&
947         "CodeGenFunction::EmitArraySubscriptExpr(): Illegal base type");
948
949  LValue LV = LValue::MakeAddr(Address,
950                               T.getCVRQualifiers(),
951                               getContext().getObjCGCAttrKind(T),
952                               E->getBase()->getType().getAddressSpace());
953  if (getContext().getLangOptions().ObjC1 &&
954      getContext().getLangOptions().getGCMode() != LangOptions::NonGC)
955    LValue::SetObjCNonGC(LV, !E->isOBJCGCCandidate(getContext()));
956  return LV;
957}
958
959static
960llvm::Constant *GenerateConstantVector(llvm::LLVMContext &VMContext,
961                                       llvm::SmallVector<unsigned, 4> &Elts) {
962  llvm::SmallVector<llvm::Constant *, 4> CElts;
963
964  for (unsigned i = 0, e = Elts.size(); i != e; ++i)
965    CElts.push_back(llvm::ConstantInt::get(
966                                   llvm::Type::getInt32Ty(VMContext), Elts[i]));
967
968  return llvm::ConstantVector::get(&CElts[0], CElts.size());
969}
970
971LValue CodeGenFunction::
972EmitExtVectorElementExpr(const ExtVectorElementExpr *E) {
973  // Emit the base vector as an l-value.
974  LValue Base;
975
976  // ExtVectorElementExpr's base can either be a vector or pointer to vector.
977  if (!E->isArrow()) {
978    assert(E->getBase()->getType()->isVectorType());
979    Base = EmitLValue(E->getBase());
980  } else {
981    const PointerType *PT = E->getBase()->getType()->getAs<PointerType>();
982    llvm::Value *Ptr = EmitScalarExpr(E->getBase());
983    Base = LValue::MakeAddr(Ptr, PT->getPointeeType().getCVRQualifiers(),
984                            QualType::GCNone,
985                            PT->getPointeeType().getAddressSpace());
986  }
987
988  // Encode the element access list into a vector of unsigned indices.
989  llvm::SmallVector<unsigned, 4> Indices;
990  E->getEncodedElementAccess(Indices);
991
992  if (Base.isSimple()) {
993    llvm::Constant *CV = GenerateConstantVector(VMContext, Indices);
994    return LValue::MakeExtVectorElt(Base.getAddress(), CV,
995                                    Base.getQualifiers());
996  }
997  assert(Base.isExtVectorElt() && "Can only subscript lvalue vec elts here!");
998
999  llvm::Constant *BaseElts = Base.getExtVectorElts();
1000  llvm::SmallVector<llvm::Constant *, 4> CElts;
1001
1002  for (unsigned i = 0, e = Indices.size(); i != e; ++i) {
1003    if (isa<llvm::ConstantAggregateZero>(BaseElts))
1004      CElts.push_back(llvm::ConstantInt::get(
1005                                         llvm::Type::getInt32Ty(VMContext), 0));
1006    else
1007      CElts.push_back(BaseElts->getOperand(Indices[i]));
1008  }
1009  llvm::Constant *CV = llvm::ConstantVector::get(&CElts[0], CElts.size());
1010  return LValue::MakeExtVectorElt(Base.getExtVectorAddr(), CV,
1011                                  Base.getQualifiers());
1012}
1013
1014LValue CodeGenFunction::EmitMemberExpr(const MemberExpr *E) {
1015  bool isUnion = false;
1016  bool isIvar = false;
1017  bool isNonGC = false;
1018  Expr *BaseExpr = E->getBase();
1019  llvm::Value *BaseValue = NULL;
1020  unsigned CVRQualifiers=0;
1021
1022  // If this is s.x, emit s as an lvalue.  If it is s->x, emit s as a scalar.
1023  if (E->isArrow()) {
1024    BaseValue = EmitScalarExpr(BaseExpr);
1025    const PointerType *PTy =
1026      BaseExpr->getType()->getAs<PointerType>();
1027    if (PTy->getPointeeType()->isUnionType())
1028      isUnion = true;
1029    CVRQualifiers = PTy->getPointeeType().getCVRQualifiers();
1030  } else if (isa<ObjCPropertyRefExpr>(BaseExpr) ||
1031             isa<ObjCImplicitSetterGetterRefExpr>(BaseExpr)) {
1032    RValue RV = EmitObjCPropertyGet(BaseExpr);
1033    BaseValue = RV.getAggregateAddr();
1034    if (BaseExpr->getType()->isUnionType())
1035      isUnion = true;
1036    CVRQualifiers = BaseExpr->getType().getCVRQualifiers();
1037  } else {
1038    LValue BaseLV = EmitLValue(BaseExpr);
1039    if (BaseLV.isObjCIvar())
1040      isIvar = true;
1041    if (BaseLV.isNonGC())
1042      isNonGC = true;
1043    // FIXME: this isn't right for bitfields.
1044    BaseValue = BaseLV.getAddress();
1045    QualType BaseTy = BaseExpr->getType();
1046    if (BaseTy->isUnionType())
1047      isUnion = true;
1048    CVRQualifiers = BaseTy.getCVRQualifiers();
1049  }
1050
1051  FieldDecl *Field = dyn_cast<FieldDecl>(E->getMemberDecl());
1052  // FIXME: Handle non-field member expressions
1053  assert(Field && "No code generation for non-field member references");
1054  LValue MemExpLV = EmitLValueForField(BaseValue, Field, isUnion,
1055                                       CVRQualifiers);
1056  LValue::SetObjCIvar(MemExpLV, isIvar);
1057  LValue::SetObjCNonGC(MemExpLV, isNonGC);
1058  return MemExpLV;
1059}
1060
1061LValue CodeGenFunction::EmitLValueForBitfield(llvm::Value* BaseValue,
1062                                              FieldDecl* Field,
1063                                              unsigned CVRQualifiers) {
1064  CodeGenTypes::BitFieldInfo Info = CGM.getTypes().getBitFieldInfo(Field);
1065
1066  // FIXME: CodeGenTypes should expose a method to get the appropriate type for
1067  // FieldTy (the appropriate type is ABI-dependent).
1068  const llvm::Type *FieldTy =
1069    CGM.getTypes().ConvertTypeForMem(Field->getType());
1070  const llvm::PointerType *BaseTy =
1071  cast<llvm::PointerType>(BaseValue->getType());
1072  unsigned AS = BaseTy->getAddressSpace();
1073  BaseValue = Builder.CreateBitCast(BaseValue,
1074                                    llvm::PointerType::get(FieldTy, AS),
1075                                    "tmp");
1076
1077  llvm::Value *Idx =
1078    llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext), Info.FieldNo);
1079  llvm::Value *V = Builder.CreateGEP(BaseValue, Idx, "tmp");
1080
1081  return LValue::MakeBitfield(V, Info.Start, Info.Size,
1082                              Field->getType()->isSignedIntegerType(),
1083                            Field->getType().getCVRQualifiers()|CVRQualifiers);
1084}
1085
1086LValue CodeGenFunction::EmitLValueForField(llvm::Value* BaseValue,
1087                                           FieldDecl* Field,
1088                                           bool isUnion,
1089                                           unsigned CVRQualifiers)
1090{
1091  if (Field->isBitField())
1092    return EmitLValueForBitfield(BaseValue, Field, CVRQualifiers);
1093
1094  unsigned idx = CGM.getTypes().getLLVMFieldNo(Field);
1095  llvm::Value *V = Builder.CreateStructGEP(BaseValue, idx, "tmp");
1096
1097  // Match union field type.
1098  if (isUnion) {
1099    const llvm::Type *FieldTy =
1100      CGM.getTypes().ConvertTypeForMem(Field->getType());
1101    const llvm::PointerType * BaseTy =
1102      cast<llvm::PointerType>(BaseValue->getType());
1103    unsigned AS = BaseTy->getAddressSpace();
1104    V = Builder.CreateBitCast(V,
1105                              llvm::PointerType::get(FieldTy, AS),
1106                              "tmp");
1107  }
1108  if (Field->getType()->isReferenceType())
1109    V = Builder.CreateLoad(V, "tmp");
1110
1111  QualType::GCAttrTypes attr = QualType::GCNone;
1112  if (CGM.getLangOptions().ObjC1 &&
1113      CGM.getLangOptions().getGCMode() != LangOptions::NonGC) {
1114    QualType Ty = Field->getType();
1115    attr = Ty.getObjCGCAttr();
1116    if (attr != QualType::GCNone) {
1117      // __weak attribute on a field is ignored.
1118      if (attr == QualType::Weak)
1119        attr = QualType::GCNone;
1120    } else if (Ty->isObjCObjectPointerType())
1121      attr = QualType::Strong;
1122  }
1123  LValue LV =
1124    LValue::MakeAddr(V,
1125                     Field->getType().getCVRQualifiers()|CVRQualifiers,
1126                     attr,
1127                     Field->getType().getAddressSpace());
1128  return LV;
1129}
1130
1131LValue CodeGenFunction::EmitCompoundLiteralLValue(const CompoundLiteralExpr* E){
1132  const llvm::Type *LTy = ConvertType(E->getType());
1133  llvm::Value *DeclPtr = CreateTempAlloca(LTy, ".compoundliteral");
1134
1135  const Expr* InitExpr = E->getInitializer();
1136  LValue Result = LValue::MakeAddr(DeclPtr, E->getType().getCVRQualifiers(),
1137                                   QualType::GCNone,
1138                                   E->getType().getAddressSpace());
1139
1140  if (E->getType()->isComplexType()) {
1141    EmitComplexExprIntoAddr(InitExpr, DeclPtr, false);
1142  } else if (hasAggregateLLVMType(E->getType())) {
1143    EmitAnyExpr(InitExpr, DeclPtr, false);
1144  } else {
1145    EmitStoreThroughLValue(EmitAnyExpr(InitExpr), Result, E->getType());
1146  }
1147
1148  return Result;
1149}
1150
1151LValue CodeGenFunction::EmitConditionalOperator(const ConditionalOperator* E) {
1152  if (E->isLvalue(getContext()) == Expr::LV_Valid)
1153    return EmitUnsupportedLValue(E, "conditional operator");
1154
1155  // ?: here should be an aggregate.
1156  assert((hasAggregateLLVMType(E->getType()) &&
1157          !E->getType()->isAnyComplexType()) &&
1158         "Unexpected conditional operator!");
1159
1160  llvm::Value *Temp = CreateTempAlloca(ConvertType(E->getType()));
1161  EmitAggExpr(E, Temp, false);
1162
1163  return LValue::MakeAddr(Temp, E->getType().getCVRQualifiers(),
1164                          getContext().getObjCGCAttrKind(E->getType()),
1165                          E->getType().getAddressSpace());
1166
1167}
1168
1169/// EmitCastLValue - Casts are never lvalues.  If a cast is needed by the code
1170/// generator in an lvalue context, then it must mean that we need the address
1171/// of an aggregate in order to access one of its fields.  This can happen for
1172/// all the reasons that casts are permitted with aggregate result, including
1173/// noop aggregate casts, and cast from scalar to union.
1174LValue CodeGenFunction::EmitCastLValue(const CastExpr *E) {
1175  if (E->getCastKind() == CastExpr::CK_UserDefinedConversion) {
1176    if (const CXXFunctionalCastExpr *CXXFExpr =
1177          dyn_cast<CXXFunctionalCastExpr>(E))
1178      return  LValue::MakeAddr(
1179                EmitCXXFunctionalCastExpr(CXXFExpr).getScalarVal(), 0);
1180    assert(isa<CStyleCastExpr>(E) &&
1181           "EmitCastLValue - Expected CStyleCastExpr");
1182    return EmitLValue(E->getSubExpr());
1183  }
1184
1185  // If this is an aggregate-to-aggregate cast, just use the input's address as
1186  // the lvalue.
1187  if (E->getCastKind() == CastExpr::CK_NoOp)
1188    return EmitLValue(E->getSubExpr());
1189
1190  // If this is an lvalue cast, treat it as a no-op.
1191  // FIXME: We shouldn't need to check for this explicitly!
1192  if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E))
1193    if (ICE->isLvalueCast())
1194      return EmitLValue(E->getSubExpr());
1195
1196  // Otherwise, we must have a cast from scalar to union.
1197  assert(E->getCastKind() == CastExpr::CK_ToUnion &&
1198         "Expected scalar-to-union cast");
1199
1200  // Casts are only lvalues when the source and destination types are the same.
1201  llvm::Value *Temp = CreateTempAlloca(ConvertType(E->getType()));
1202  EmitAnyExpr(E->getSubExpr(), Temp, false);
1203
1204  return LValue::MakeAddr(Temp, E->getType().getCVRQualifiers(),
1205                          getContext().getObjCGCAttrKind(E->getType()),
1206                          E->getType().getAddressSpace());
1207}
1208
1209//===--------------------------------------------------------------------===//
1210//                             Expression Emission
1211//===--------------------------------------------------------------------===//
1212
1213
1214RValue CodeGenFunction::EmitCallExpr(const CallExpr *E) {
1215  // Builtins never have block type.
1216  if (E->getCallee()->getType()->isBlockPointerType())
1217    return EmitBlockCallExpr(E);
1218
1219  if (const CXXMemberCallExpr *CE = dyn_cast<CXXMemberCallExpr>(E))
1220    return EmitCXXMemberCallExpr(CE);
1221
1222  const Decl *TargetDecl = 0;
1223  if (const ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(E->getCallee())) {
1224    if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(CE->getSubExpr())) {
1225      TargetDecl = DRE->getDecl();
1226      if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(TargetDecl))
1227        if (unsigned builtinID = FD->getBuiltinID(getContext()))
1228          return EmitBuiltinExpr(FD, builtinID, E);
1229    }
1230  }
1231
1232  if (const CXXOperatorCallExpr *CE = dyn_cast<CXXOperatorCallExpr>(E))
1233    if (const CXXMethodDecl *MD = dyn_cast_or_null<CXXMethodDecl>(TargetDecl))
1234      return EmitCXXOperatorMemberCallExpr(CE, MD);
1235
1236  llvm::Value *Callee = EmitScalarExpr(E->getCallee());
1237  return EmitCall(Callee, E->getCallee()->getType(),
1238                  E->arg_begin(), E->arg_end(), TargetDecl);
1239}
1240
1241LValue CodeGenFunction::EmitBinaryOperatorLValue(const BinaryOperator *E) {
1242  // Comma expressions just emit their LHS then their RHS as an l-value.
1243  if (E->getOpcode() == BinaryOperator::Comma) {
1244    EmitAnyExpr(E->getLHS());
1245    return EmitLValue(E->getRHS());
1246  }
1247
1248  // Can only get l-value for binary operator expressions which are a
1249  // simple assignment of aggregate type.
1250  if (E->getOpcode() != BinaryOperator::Assign)
1251    return EmitUnsupportedLValue(E, "binary l-value expression");
1252
1253  llvm::Value *Temp = CreateTempAlloca(ConvertType(E->getType()));
1254  EmitAggExpr(E, Temp, false);
1255  // FIXME: Are these qualifiers correct?
1256  return LValue::MakeAddr(Temp, E->getType().getCVRQualifiers(),
1257                          getContext().getObjCGCAttrKind(E->getType()),
1258                          E->getType().getAddressSpace());
1259}
1260
1261LValue CodeGenFunction::EmitCallExprLValue(const CallExpr *E) {
1262  RValue RV = EmitCallExpr(E);
1263
1264  if (RV.isScalar()) {
1265    assert(E->getCallReturnType()->isReferenceType() &&
1266           "Can't have a scalar return unless the return type is a "
1267           "reference type!");
1268
1269    return LValue::MakeAddr(RV.getScalarVal(), E->getType().getCVRQualifiers(),
1270                            getContext().getObjCGCAttrKind(E->getType()),
1271                            E->getType().getAddressSpace());
1272  }
1273
1274  return LValue::MakeAddr(RV.getAggregateAddr(),
1275                          E->getType().getCVRQualifiers(),
1276                          getContext().getObjCGCAttrKind(E->getType()),
1277                          E->getType().getAddressSpace());
1278}
1279
1280LValue CodeGenFunction::EmitVAArgExprLValue(const VAArgExpr *E) {
1281  // FIXME: This shouldn't require another copy.
1282  llvm::Value *Temp = CreateTempAlloca(ConvertType(E->getType()));
1283  EmitAggExpr(E, Temp, false);
1284  return LValue::MakeAddr(Temp, E->getType().getCVRQualifiers(),
1285                          QualType::GCNone, E->getType().getAddressSpace());
1286}
1287
1288LValue
1289CodeGenFunction::EmitCXXConditionDeclLValue(const CXXConditionDeclExpr *E) {
1290  EmitLocalBlockVarDecl(*E->getVarDecl());
1291  return EmitDeclRefLValue(E);
1292}
1293
1294LValue CodeGenFunction::EmitCXXConstructLValue(const CXXConstructExpr *E) {
1295  llvm::Value *Temp = CreateTempAlloca(ConvertTypeForMem(E->getType()), "tmp");
1296  EmitCXXConstructExpr(Temp, E);
1297  return LValue::MakeAddr(Temp, E->getType().getCVRQualifiers(),
1298                          QualType::GCNone, E->getType().getAddressSpace());
1299}
1300
1301LValue
1302CodeGenFunction::EmitCXXBindTemporaryLValue(const CXXBindTemporaryExpr *E) {
1303  LValue LV = EmitLValue(E->getSubExpr());
1304
1305  PushCXXTemporary(E->getTemporary(), LV.getAddress());
1306
1307  return LV;
1308}
1309
1310LValue CodeGenFunction::EmitObjCMessageExprLValue(const ObjCMessageExpr *E) {
1311  // Can only get l-value for message expression returning aggregate type
1312  RValue RV = EmitObjCMessageExpr(E);
1313  // FIXME: can this be volatile?
1314  return LValue::MakeAddr(RV.getAggregateAddr(),
1315                          E->getType().getCVRQualifiers(),
1316                          getContext().getObjCGCAttrKind(E->getType()),
1317                          E->getType().getAddressSpace());
1318}
1319
1320llvm::Value *CodeGenFunction::EmitIvarOffset(const ObjCInterfaceDecl *Interface,
1321                                             const ObjCIvarDecl *Ivar) {
1322  return CGM.getObjCRuntime().EmitIvarOffset(*this, Interface, Ivar);
1323}
1324
1325LValue CodeGenFunction::EmitLValueForIvar(QualType ObjectTy,
1326                                          llvm::Value *BaseValue,
1327                                          const ObjCIvarDecl *Ivar,
1328                                          unsigned CVRQualifiers) {
1329  return CGM.getObjCRuntime().EmitObjCValueForIvar(*this, ObjectTy, BaseValue,
1330                                                   Ivar, CVRQualifiers);
1331}
1332
1333LValue CodeGenFunction::EmitObjCIvarRefLValue(const ObjCIvarRefExpr *E) {
1334  // FIXME: A lot of the code below could be shared with EmitMemberExpr.
1335  llvm::Value *BaseValue = 0;
1336  const Expr *BaseExpr = E->getBase();
1337  unsigned CVRQualifiers = 0;
1338  QualType ObjectTy;
1339  if (E->isArrow()) {
1340    BaseValue = EmitScalarExpr(BaseExpr);
1341    ObjectTy = BaseExpr->getType()->getPointeeType();
1342    CVRQualifiers = ObjectTy.getCVRQualifiers();
1343  } else {
1344    LValue BaseLV = EmitLValue(BaseExpr);
1345    // FIXME: this isn't right for bitfields.
1346    BaseValue = BaseLV.getAddress();
1347    ObjectTy = BaseExpr->getType();
1348    CVRQualifiers = ObjectTy.getCVRQualifiers();
1349  }
1350
1351  return EmitLValueForIvar(ObjectTy, BaseValue, E->getDecl(), CVRQualifiers);
1352}
1353
1354LValue
1355CodeGenFunction::EmitObjCPropertyRefLValue(const ObjCPropertyRefExpr *E) {
1356  // This is a special l-value that just issues sends when we load or
1357  // store through it.
1358  return LValue::MakePropertyRef(E, E->getType().getCVRQualifiers());
1359}
1360
1361LValue
1362CodeGenFunction::EmitObjCKVCRefLValue(
1363                                const ObjCImplicitSetterGetterRefExpr *E) {
1364  // This is a special l-value that just issues sends when we load or
1365  // store through it.
1366  return LValue::MakeKVCRef(E, E->getType().getCVRQualifiers());
1367}
1368
1369LValue
1370CodeGenFunction::EmitObjCSuperExprLValue(const ObjCSuperExpr *E) {
1371  return EmitUnsupportedLValue(E, "use of super");
1372}
1373
1374LValue CodeGenFunction::EmitStmtExprLValue(const StmtExpr *E) {
1375
1376  // Can only get l-value for message expression returning aggregate type
1377  RValue RV = EmitAnyExprToTemp(E);
1378  // FIXME: can this be volatile?
1379  return LValue::MakeAddr(RV.getAggregateAddr(),
1380                          E->getType().getCVRQualifiers(),
1381                          getContext().getObjCGCAttrKind(E->getType()),
1382                          E->getType().getAddressSpace());
1383}
1384
1385
1386RValue CodeGenFunction::EmitCall(llvm::Value *Callee, QualType CalleeType,
1387                                 CallExpr::const_arg_iterator ArgBeg,
1388                                 CallExpr::const_arg_iterator ArgEnd,
1389                                 const Decl *TargetDecl) {
1390  // Get the actual function type. The callee type will always be a
1391  // pointer to function type or a block pointer type.
1392  assert(CalleeType->isFunctionPointerType() &&
1393         "Call must have function pointer type!");
1394
1395  QualType FnType = CalleeType->getAs<PointerType>()->getPointeeType();
1396  QualType ResultType = FnType->getAsFunctionType()->getResultType();
1397
1398  CallArgList Args;
1399  EmitCallArgs(Args, FnType->getAsFunctionProtoType(), ArgBeg, ArgEnd);
1400
1401  return EmitCall(CGM.getTypes().getFunctionInfo(ResultType, Args),
1402                  Callee, Args, TargetDecl);
1403}
1404