CGExpr.cpp revision 77b89b87c3b9220fea1bc80f6d6598d2003cc8a8 
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 "CGRecordLayout.h"
18#include "CGObjCRuntime.h"
19#include "clang/AST/ASTContext.h"
20#include "clang/AST/DeclObjC.h"
21#include "llvm/Intrinsics.h"
22#include "clang/Frontend/CodeGenOptions.h"
23#include "llvm/Target/TargetData.h"
24using namespace clang;
25using namespace CodeGen;
26
27//===--------------------------------------------------------------------===//
28//                        Miscellaneous Helper Methods
29//===--------------------------------------------------------------------===//
30
31/// CreateTempAlloca - This creates a alloca and inserts it into the entry
32/// block.
33llvm::AllocaInst *CodeGenFunction::CreateTempAlloca(const llvm::Type *Ty,
34                                                    const llvm::Twine &Name) {
35  if (!Builder.isNamePreserving())
36    return new llvm::AllocaInst(Ty, 0, "", AllocaInsertPt);
37  return new llvm::AllocaInst(Ty, 0, Name, AllocaInsertPt);
38}
39
40void CodeGenFunction::InitTempAlloca(llvm::AllocaInst *Var,
41                                     llvm::Value *Init) {
42  llvm::StoreInst *Store = new llvm::StoreInst(Init, Var);
43  llvm::BasicBlock *Block = AllocaInsertPt->getParent();
44  Block->getInstList().insertAfter(&*AllocaInsertPt, Store);
45}
46
47llvm::Value *CodeGenFunction::CreateIRTemp(QualType Ty,
48                                           const llvm::Twine &Name) {
49  llvm::AllocaInst *Alloc = CreateTempAlloca(ConvertType(Ty), Name);
50  // FIXME: Should we prefer the preferred type alignment here?
51  CharUnits Align = getContext().getTypeAlignInChars(Ty);
52  Alloc->setAlignment(Align.getQuantity());
53  return Alloc;
54}
55
56llvm::Value *CodeGenFunction::CreateMemTemp(QualType Ty,
57                                            const llvm::Twine &Name) {
58  llvm::AllocaInst *Alloc = CreateTempAlloca(ConvertTypeForMem(Ty), Name);
59  // FIXME: Should we prefer the preferred type alignment here?
60  CharUnits Align = getContext().getTypeAlignInChars(Ty);
61  Alloc->setAlignment(Align.getQuantity());
62  return Alloc;
63}
64
65/// EvaluateExprAsBool - Perform the usual unary conversions on the specified
66/// expression and compare the result against zero, returning an Int1Ty value.
67llvm::Value *CodeGenFunction::EvaluateExprAsBool(const Expr *E) {
68  QualType BoolTy = getContext().BoolTy;
69  if (E->getType()->isMemberFunctionPointerType()) {
70    LValue LV = EmitAggExprToLValue(E);
71
72    // Get the pointer.
73    llvm::Value *FuncPtr = Builder.CreateStructGEP(LV.getAddress(), 0,
74                                                   "src.ptr");
75    FuncPtr = Builder.CreateLoad(FuncPtr);
76
77    llvm::Value *IsNotNull =
78      Builder.CreateICmpNE(FuncPtr,
79                            llvm::Constant::getNullValue(FuncPtr->getType()),
80                            "tobool");
81
82    return IsNotNull;
83  }
84  if (!E->getType()->isAnyComplexType())
85    return EmitScalarConversion(EmitScalarExpr(E), E->getType(), BoolTy);
86
87  return EmitComplexToScalarConversion(EmitComplexExpr(E), E->getType(),BoolTy);
88}
89
90/// EmitAnyExpr - Emit code to compute the specified expression which can have
91/// any type.  The result is returned as an RValue struct.  If this is an
92/// aggregate expression, the aggloc/agglocvolatile arguments indicate where the
93/// result should be returned.
94RValue CodeGenFunction::EmitAnyExpr(const Expr *E, llvm::Value *AggLoc,
95                                    bool IsAggLocVolatile, bool IgnoreResult,
96                                    bool IsInitializer) {
97  if (!hasAggregateLLVMType(E->getType()))
98    return RValue::get(EmitScalarExpr(E, IgnoreResult));
99  else if (E->getType()->isAnyComplexType())
100    return RValue::getComplex(EmitComplexExpr(E, false, false,
101                                              IgnoreResult, IgnoreResult));
102
103  EmitAggExpr(E, AggLoc, IsAggLocVolatile, IgnoreResult, IsInitializer);
104  return RValue::getAggregate(AggLoc, IsAggLocVolatile);
105}
106
107/// EmitAnyExprToTemp - Similary to EmitAnyExpr(), however, the result will
108/// always be accessible even if no aggregate location is provided.
109RValue CodeGenFunction::EmitAnyExprToTemp(const Expr *E,
110                                          bool IsAggLocVolatile,
111                                          bool IsInitializer) {
112  llvm::Value *AggLoc = 0;
113
114  if (hasAggregateLLVMType(E->getType()) &&
115      !E->getType()->isAnyComplexType())
116    AggLoc = CreateMemTemp(E->getType(), "agg.tmp");
117  return EmitAnyExpr(E, AggLoc, IsAggLocVolatile, /*IgnoreResult=*/false,
118                     IsInitializer);
119}
120
121/// EmitAnyExprToMem - Evaluate an expression into a given memory
122/// location.
123void CodeGenFunction::EmitAnyExprToMem(const Expr *E,
124                                       llvm::Value *Location,
125                                       bool IsLocationVolatile,
126                                       bool IsInit) {
127  if (E->getType()->isComplexType())
128    EmitComplexExprIntoAddr(E, Location, IsLocationVolatile);
129  else if (hasAggregateLLVMType(E->getType()))
130    EmitAggExpr(E, Location, IsLocationVolatile, /*Ignore*/ false, IsInit);
131  else {
132    RValue RV = RValue::get(EmitScalarExpr(E, /*Ignore*/ false));
133    LValue LV = LValue::MakeAddr(Location, MakeQualifiers(E->getType()));
134    EmitStoreThroughLValue(RV, LV, E->getType());
135  }
136}
137
138/// \brief An adjustment to be made to the temporary created when emitting a
139/// reference binding, which accesses a particular subobject of that temporary.
140struct SubobjectAdjustment {
141  enum { DerivedToBaseAdjustment, FieldAdjustment } Kind;
142
143  union {
144    struct {
145      const CXXBaseSpecifierArray *BasePath;
146      const CXXRecordDecl *DerivedClass;
147    } DerivedToBase;
148
149    struct {
150      FieldDecl *Field;
151      unsigned CVRQualifiers;
152    } Field;
153  };
154
155  SubobjectAdjustment(const CXXBaseSpecifierArray *BasePath,
156                      const CXXRecordDecl *DerivedClass)
157    : Kind(DerivedToBaseAdjustment)
158  {
159    DerivedToBase.BasePath = BasePath;
160    DerivedToBase.DerivedClass = DerivedClass;
161  }
162
163  SubobjectAdjustment(FieldDecl *Field, unsigned CVRQualifiers)
164    : Kind(FieldAdjustment)
165  {
166    this->Field.Field = Field;
167    this->Field.CVRQualifiers = CVRQualifiers;
168  }
169};
170
171RValue
172CodeGenFunction::EmitReferenceBindingToExpr(const Expr* E,
173                                            const NamedDecl *InitializedDecl) {
174  bool IsInitializer = InitializedDecl;
175
176  bool ShouldDestroyTemporaries = false;
177  unsigned OldNumLiveTemporaries = 0;
178
179  if (const CXXDefaultArgExpr *DAE = dyn_cast<CXXDefaultArgExpr>(E))
180    E = DAE->getExpr();
181
182  if (const CXXExprWithTemporaries *TE = dyn_cast<CXXExprWithTemporaries>(E)) {
183    ShouldDestroyTemporaries = true;
184
185    // Keep track of the current cleanup stack depth.
186    OldNumLiveTemporaries = LiveTemporaries.size();
187
188    E = TE->getSubExpr();
189  }
190
191  RValue Val;
192  if (E->isLvalue(getContext()) == Expr::LV_Valid) {
193    // Emit the expr as an lvalue.
194    LValue LV = EmitLValue(E);
195    if (LV.isSimple()) {
196      if (ShouldDestroyTemporaries) {
197        // Pop temporaries.
198        while (LiveTemporaries.size() > OldNumLiveTemporaries)
199          PopCXXTemporary();
200      }
201
202      return RValue::get(LV.getAddress());
203    }
204
205    Val = EmitLoadOfLValue(LV, E->getType());
206
207    if (ShouldDestroyTemporaries) {
208      // Pop temporaries.
209      while (LiveTemporaries.size() > OldNumLiveTemporaries)
210        PopCXXTemporary();
211    }
212  } else {
213    QualType ResultTy = E->getType();
214
215    llvm::SmallVector<SubobjectAdjustment, 2> Adjustments;
216    do {
217      if (const ParenExpr *PE = dyn_cast<ParenExpr>(E)) {
218        E = PE->getSubExpr();
219        continue;
220      }
221
222      if (const CastExpr *CE = dyn_cast<CastExpr>(E)) {
223        if ((CE->getCastKind() == CastExpr::CK_DerivedToBase ||
224             CE->getCastKind() == CastExpr::CK_UncheckedDerivedToBase) &&
225            E->getType()->isRecordType()) {
226          E = CE->getSubExpr();
227          CXXRecordDecl *Derived
228            = cast<CXXRecordDecl>(E->getType()->getAs<RecordType>()->getDecl());
229          Adjustments.push_back(SubobjectAdjustment(&CE->getBasePath(),
230                                                    Derived));
231          continue;
232        }
233
234        if (CE->getCastKind() == CastExpr::CK_NoOp) {
235          E = CE->getSubExpr();
236          continue;
237        }
238      } else if (const MemberExpr *ME = dyn_cast<MemberExpr>(E)) {
239        if (ME->getBase()->isLvalue(getContext()) != Expr::LV_Valid &&
240            ME->getBase()->getType()->isRecordType()) {
241          if (FieldDecl *Field = dyn_cast<FieldDecl>(ME->getMemberDecl())) {
242            E = ME->getBase();
243            Adjustments.push_back(SubobjectAdjustment(Field,
244                                              E->getType().getCVRQualifiers()));
245            continue;
246          }
247        }
248      }
249
250      // Nothing changed.
251      break;
252    } while (true);
253
254    Val = EmitAnyExprToTemp(E, /*IsAggLocVolatile=*/false,
255                            IsInitializer);
256
257    if (ShouldDestroyTemporaries) {
258      // Pop temporaries.
259      while (LiveTemporaries.size() > OldNumLiveTemporaries)
260        PopCXXTemporary();
261    }
262
263    if (IsInitializer) {
264      // We might have to destroy the temporary variable.
265      if (const RecordType *RT = E->getType()->getAs<RecordType>()) {
266        if (CXXRecordDecl *ClassDecl = dyn_cast<CXXRecordDecl>(RT->getDecl())) {
267          if (!ClassDecl->hasTrivialDestructor()) {
268            const CXXDestructorDecl *Dtor =
269              ClassDecl->getDestructor(getContext());
270
271            {
272              DelayedCleanupBlock Scope(*this);
273              EmitCXXDestructorCall(Dtor, Dtor_Complete,
274                                    /*ForVirtualBase=*/false,
275                                    Val.getAggregateAddr());
276
277              // Make sure to jump to the exit block.
278              EmitBranch(Scope.getCleanupExitBlock());
279            }
280            if (Exceptions) {
281              EHCleanupBlock Cleanup(*this);
282              EmitCXXDestructorCall(Dtor, Dtor_Complete,
283                                    /*ForVirtualBase=*/false,
284                                    Val.getAggregateAddr());
285            }
286          }
287        }
288      }
289    }
290
291    // Check if need to perform derived-to-base casts and/or field accesses, to
292    // get from the temporary object we created (and, potentially, for which we
293    // extended the lifetime) to the subobject we're binding the reference to.
294    if (!Adjustments.empty()) {
295      llvm::Value *Object = Val.getAggregateAddr();
296      for (unsigned I = Adjustments.size(); I != 0; --I) {
297        SubobjectAdjustment &Adjustment = Adjustments[I-1];
298        switch (Adjustment.Kind) {
299        case SubobjectAdjustment::DerivedToBaseAdjustment:
300          Object = GetAddressOfBaseClass(Object,
301                                         Adjustment.DerivedToBase.DerivedClass,
302                                         *Adjustment.DerivedToBase.BasePath,
303                                         /*NullCheckValue=*/false);
304          break;
305
306        case SubobjectAdjustment::FieldAdjustment: {
307          unsigned CVR = Adjustment.Field.CVRQualifiers;
308          LValue LV = EmitLValueForField(Object, Adjustment.Field.Field, CVR);
309          if (LV.isSimple()) {
310            Object = LV.getAddress();
311            break;
312          }
313
314          // For non-simple lvalues, we actually have to create a copy of
315          // the object we're binding to.
316          QualType T = Adjustment.Field.Field->getType().getNonReferenceType()
317                                                        .getUnqualifiedType();
318          Object = CreateTempAlloca(ConvertType(T), "lv");
319          EmitStoreThroughLValue(EmitLoadOfLValue(LV, T),
320                                 LValue::MakeAddr(Object,
321                                                  Qualifiers::fromCVRMask(CVR)),
322                                 T);
323          break;
324        }
325        }
326      }
327
328      const llvm::Type *ResultPtrTy
329        = llvm::PointerType::get(ConvertType(ResultTy), 0);
330      Object = Builder.CreateBitCast(Object, ResultPtrTy, "temp");
331      return RValue::get(Object);
332    }
333  }
334
335  if (Val.isAggregate()) {
336    Val = RValue::get(Val.getAggregateAddr());
337  } else {
338    // Create a temporary variable that we can bind the reference to.
339    llvm::Value *Temp = CreateMemTemp(E->getType(), "reftmp");
340    if (Val.isScalar())
341      EmitStoreOfScalar(Val.getScalarVal(), Temp, false, E->getType());
342    else
343      StoreComplexToAddr(Val.getComplexVal(), Temp, false);
344    Val = RValue::get(Temp);
345  }
346
347  return Val;
348}
349
350
351/// getAccessedFieldNo - Given an encoded value and a result number, return the
352/// input field number being accessed.
353unsigned CodeGenFunction::getAccessedFieldNo(unsigned Idx,
354                                             const llvm::Constant *Elts) {
355  if (isa<llvm::ConstantAggregateZero>(Elts))
356    return 0;
357
358  return cast<llvm::ConstantInt>(Elts->getOperand(Idx))->getZExtValue();
359}
360
361void CodeGenFunction::EmitCheck(llvm::Value *Address, unsigned Size) {
362  if (!CatchUndefined)
363    return;
364
365  Address = Builder.CreateBitCast(Address, PtrToInt8Ty);
366
367  const llvm::Type *IntPtrT = IntPtrTy;
368  llvm::Value *F = CGM.getIntrinsic(llvm::Intrinsic::objectsize, &IntPtrT, 1);
369  const llvm::IntegerType *Int1Ty = llvm::Type::getInt1Ty(VMContext);
370
371  // In time, people may want to control this and use a 1 here.
372  llvm::Value *Arg = llvm::ConstantInt::get(Int1Ty, 0);
373  llvm::Value *C = Builder.CreateCall2(F, Address, Arg);
374  llvm::BasicBlock *Cont = createBasicBlock();
375  llvm::BasicBlock *Check = createBasicBlock();
376  llvm::Value *NegativeOne = llvm::ConstantInt::get(IntPtrTy, -1ULL);
377  Builder.CreateCondBr(Builder.CreateICmpEQ(C, NegativeOne), Cont, Check);
378
379  EmitBlock(Check);
380  Builder.CreateCondBr(Builder.CreateICmpUGE(C,
381                                        llvm::ConstantInt::get(IntPtrTy, Size)),
382                       Cont, getTrapBB());
383  EmitBlock(Cont);
384}
385
386
387CodeGenFunction::ComplexPairTy CodeGenFunction::
388EmitComplexPrePostIncDec(const UnaryOperator *E, LValue LV,
389                         bool isInc, bool isPre) {
390  ComplexPairTy InVal = LoadComplexFromAddr(LV.getAddress(),
391                                            LV.isVolatileQualified());
392
393  llvm::Value *NextVal;
394  if (isa<llvm::IntegerType>(InVal.first->getType())) {
395    uint64_t AmountVal = isInc ? 1 : -1;
396    NextVal = llvm::ConstantInt::get(InVal.first->getType(), AmountVal, true);
397
398    // Add the inc/dec to the real part.
399    NextVal = Builder.CreateAdd(InVal.first, NextVal, isInc ? "inc" : "dec");
400  } else {
401    QualType ElemTy = E->getType()->getAs<ComplexType>()->getElementType();
402    llvm::APFloat FVal(getContext().getFloatTypeSemantics(ElemTy), 1);
403    if (!isInc)
404      FVal.changeSign();
405    NextVal = llvm::ConstantFP::get(getLLVMContext(), FVal);
406
407    // Add the inc/dec to the real part.
408    NextVal = Builder.CreateFAdd(InVal.first, NextVal, isInc ? "inc" : "dec");
409  }
410
411  ComplexPairTy IncVal(NextVal, InVal.second);
412
413  // Store the updated result through the lvalue.
414  StoreComplexToAddr(IncVal, LV.getAddress(), LV.isVolatileQualified());
415
416  // If this is a postinc, return the value read from memory, otherwise use the
417  // updated value.
418  return isPre ? IncVal : InVal;
419}
420
421
422//===----------------------------------------------------------------------===//
423//                         LValue Expression Emission
424//===----------------------------------------------------------------------===//
425
426RValue CodeGenFunction::GetUndefRValue(QualType Ty) {
427  if (Ty->isVoidType())
428    return RValue::get(0);
429
430  if (const ComplexType *CTy = Ty->getAs<ComplexType>()) {
431    const llvm::Type *EltTy = ConvertType(CTy->getElementType());
432    llvm::Value *U = llvm::UndefValue::get(EltTy);
433    return RValue::getComplex(std::make_pair(U, U));
434  }
435
436  if (hasAggregateLLVMType(Ty)) {
437    const llvm::Type *LTy = llvm::PointerType::getUnqual(ConvertType(Ty));
438    return RValue::getAggregate(llvm::UndefValue::get(LTy));
439  }
440
441  return RValue::get(llvm::UndefValue::get(ConvertType(Ty)));
442}
443
444RValue CodeGenFunction::EmitUnsupportedRValue(const Expr *E,
445                                              const char *Name) {
446  ErrorUnsupported(E, Name);
447  return GetUndefRValue(E->getType());
448}
449
450LValue CodeGenFunction::EmitUnsupportedLValue(const Expr *E,
451                                              const char *Name) {
452  ErrorUnsupported(E, Name);
453  llvm::Type *Ty = llvm::PointerType::getUnqual(ConvertType(E->getType()));
454  return LValue::MakeAddr(llvm::UndefValue::get(Ty),
455                          MakeQualifiers(E->getType()));
456}
457
458LValue CodeGenFunction::EmitCheckedLValue(const Expr *E) {
459  LValue LV = EmitLValue(E);
460  if (!isa<DeclRefExpr>(E) && !LV.isBitField() && LV.isSimple())
461    EmitCheck(LV.getAddress(), getContext().getTypeSize(E->getType()) / 8);
462  return LV;
463}
464
465/// EmitLValue - Emit code to compute a designator that specifies the location
466/// of the expression.
467///
468/// This can return one of two things: a simple address or a bitfield reference.
469/// In either case, the LLVM Value* in the LValue structure is guaranteed to be
470/// an LLVM pointer type.
471///
472/// If this returns a bitfield reference, nothing about the pointee type of the
473/// LLVM value is known: For example, it may not be a pointer to an integer.
474///
475/// If this returns a normal address, and if the lvalue's C type is fixed size,
476/// this method guarantees that the returned pointer type will point to an LLVM
477/// type of the same size of the lvalue's type.  If the lvalue has a variable
478/// length type, this is not possible.
479///
480LValue CodeGenFunction::EmitLValue(const Expr *E) {
481  switch (E->getStmtClass()) {
482  default: return EmitUnsupportedLValue(E, "l-value expression");
483
484  case Expr::ObjCSelectorExprClass:
485  return EmitObjCSelectorLValue(cast<ObjCSelectorExpr>(E));
486  case Expr::ObjCIsaExprClass:
487    return EmitObjCIsaExpr(cast<ObjCIsaExpr>(E));
488  case Expr::BinaryOperatorClass:
489    return EmitBinaryOperatorLValue(cast<BinaryOperator>(E));
490  case Expr::CompoundAssignOperatorClass:
491    return EmitCompoundAssignOperatorLValue(cast<CompoundAssignOperator>(E));
492  case Expr::CallExprClass:
493  case Expr::CXXMemberCallExprClass:
494  case Expr::CXXOperatorCallExprClass:
495    return EmitCallExprLValue(cast<CallExpr>(E));
496  case Expr::VAArgExprClass:
497    return EmitVAArgExprLValue(cast<VAArgExpr>(E));
498  case Expr::DeclRefExprClass:
499    return EmitDeclRefLValue(cast<DeclRefExpr>(E));
500  case Expr::ParenExprClass:return EmitLValue(cast<ParenExpr>(E)->getSubExpr());
501  case Expr::PredefinedExprClass:
502    return EmitPredefinedLValue(cast<PredefinedExpr>(E));
503  case Expr::StringLiteralClass:
504    return EmitStringLiteralLValue(cast<StringLiteral>(E));
505  case Expr::ObjCEncodeExprClass:
506    return EmitObjCEncodeExprLValue(cast<ObjCEncodeExpr>(E));
507
508  case Expr::BlockDeclRefExprClass:
509    return EmitBlockDeclRefLValue(cast<BlockDeclRefExpr>(E));
510
511  case Expr::CXXTemporaryObjectExprClass:
512  case Expr::CXXConstructExprClass:
513    return EmitCXXConstructLValue(cast<CXXConstructExpr>(E));
514  case Expr::CXXBindTemporaryExprClass:
515    return EmitCXXBindTemporaryLValue(cast<CXXBindTemporaryExpr>(E));
516  case Expr::CXXExprWithTemporariesClass:
517    return EmitCXXExprWithTemporariesLValue(cast<CXXExprWithTemporaries>(E));
518  case Expr::CXXZeroInitValueExprClass:
519    return EmitNullInitializationLValue(cast<CXXZeroInitValueExpr>(E));
520  case Expr::CXXDefaultArgExprClass:
521    return EmitLValue(cast<CXXDefaultArgExpr>(E)->getExpr());
522  case Expr::CXXTypeidExprClass:
523    return EmitCXXTypeidLValue(cast<CXXTypeidExpr>(E));
524
525  case Expr::ObjCMessageExprClass:
526    return EmitObjCMessageExprLValue(cast<ObjCMessageExpr>(E));
527  case Expr::ObjCIvarRefExprClass:
528    return EmitObjCIvarRefLValue(cast<ObjCIvarRefExpr>(E));
529  case Expr::ObjCPropertyRefExprClass:
530    return EmitObjCPropertyRefLValue(cast<ObjCPropertyRefExpr>(E));
531  case Expr::ObjCImplicitSetterGetterRefExprClass:
532    return EmitObjCKVCRefLValue(cast<ObjCImplicitSetterGetterRefExpr>(E));
533  case Expr::ObjCSuperExprClass:
534    return EmitObjCSuperExprLValue(cast<ObjCSuperExpr>(E));
535
536  case Expr::StmtExprClass:
537    return EmitStmtExprLValue(cast<StmtExpr>(E));
538  case Expr::UnaryOperatorClass:
539    return EmitUnaryOpLValue(cast<UnaryOperator>(E));
540  case Expr::ArraySubscriptExprClass:
541    return EmitArraySubscriptExpr(cast<ArraySubscriptExpr>(E));
542  case Expr::ExtVectorElementExprClass:
543    return EmitExtVectorElementExpr(cast<ExtVectorElementExpr>(E));
544  case Expr::MemberExprClass:
545    return EmitMemberExpr(cast<MemberExpr>(E));
546  case Expr::CompoundLiteralExprClass:
547    return EmitCompoundLiteralLValue(cast<CompoundLiteralExpr>(E));
548  case Expr::ConditionalOperatorClass:
549    return EmitConditionalOperatorLValue(cast<ConditionalOperator>(E));
550  case Expr::ChooseExprClass:
551    return EmitLValue(cast<ChooseExpr>(E)->getChosenSubExpr(getContext()));
552  case Expr::ImplicitCastExprClass:
553  case Expr::CStyleCastExprClass:
554  case Expr::CXXFunctionalCastExprClass:
555  case Expr::CXXStaticCastExprClass:
556  case Expr::CXXDynamicCastExprClass:
557  case Expr::CXXReinterpretCastExprClass:
558  case Expr::CXXConstCastExprClass:
559    return EmitCastLValue(cast<CastExpr>(E));
560  }
561}
562
563llvm::Value *CodeGenFunction::EmitLoadOfScalar(llvm::Value *Addr, bool Volatile,
564                                               QualType Ty) {
565  llvm::LoadInst *Load = Builder.CreateLoad(Addr, "tmp");
566  if (Volatile)
567    Load->setVolatile(true);
568
569  // Bool can have different representation in memory than in registers.
570  llvm::Value *V = Load;
571  if (Ty->isBooleanType())
572    if (V->getType() != llvm::Type::getInt1Ty(VMContext))
573      V = Builder.CreateTrunc(V, llvm::Type::getInt1Ty(VMContext), "tobool");
574
575  return V;
576}
577
578void CodeGenFunction::EmitStoreOfScalar(llvm::Value *Value, llvm::Value *Addr,
579                                        bool Volatile, QualType Ty) {
580
581  if (Ty->isBooleanType()) {
582    // Bool can have different representation in memory than in registers.
583    const llvm::PointerType *DstPtr = cast<llvm::PointerType>(Addr->getType());
584    Value = Builder.CreateIntCast(Value, DstPtr->getElementType(), false);
585  }
586  Builder.CreateStore(Value, Addr, Volatile);
587}
588
589/// EmitLoadOfLValue - Given an expression that represents a value lvalue, this
590/// method emits the address of the lvalue, then loads the result as an rvalue,
591/// returning the rvalue.
592RValue CodeGenFunction::EmitLoadOfLValue(LValue LV, QualType ExprType) {
593  if (LV.isObjCWeak()) {
594    // load of a __weak object.
595    llvm::Value *AddrWeakObj = LV.getAddress();
596    return RValue::get(CGM.getObjCRuntime().EmitObjCWeakRead(*this,
597                                                             AddrWeakObj));
598  }
599
600  if (LV.isSimple()) {
601    llvm::Value *Ptr = LV.getAddress();
602    const llvm::Type *EltTy =
603      cast<llvm::PointerType>(Ptr->getType())->getElementType();
604
605    // Simple scalar l-value.
606    //
607    // FIXME: We shouldn't have to use isSingleValueType here.
608    if (EltTy->isSingleValueType())
609      return RValue::get(EmitLoadOfScalar(Ptr, LV.isVolatileQualified(),
610                                          ExprType));
611
612    assert(ExprType->isFunctionType() && "Unknown scalar value");
613    return RValue::get(Ptr);
614  }
615
616  if (LV.isVectorElt()) {
617    llvm::Value *Vec = Builder.CreateLoad(LV.getVectorAddr(),
618                                          LV.isVolatileQualified(), "tmp");
619    return RValue::get(Builder.CreateExtractElement(Vec, LV.getVectorIdx(),
620                                                    "vecext"));
621  }
622
623  // If this is a reference to a subset of the elements of a vector, either
624  // shuffle the input or extract/insert them as appropriate.
625  if (LV.isExtVectorElt())
626    return EmitLoadOfExtVectorElementLValue(LV, ExprType);
627
628  if (LV.isBitField())
629    return EmitLoadOfBitfieldLValue(LV, ExprType);
630
631  if (LV.isPropertyRef())
632    return EmitLoadOfPropertyRefLValue(LV, ExprType);
633
634  assert(LV.isKVCRef() && "Unknown LValue type!");
635  return EmitLoadOfKVCRefLValue(LV, ExprType);
636}
637
638RValue CodeGenFunction::EmitLoadOfBitfieldLValue(LValue LV,
639                                                 QualType ExprType) {
640  const CGBitFieldInfo &Info = LV.getBitFieldInfo();
641
642  // Get the output type.
643  const llvm::Type *ResLTy = ConvertType(ExprType);
644  unsigned ResSizeInBits = CGM.getTargetData().getTypeSizeInBits(ResLTy);
645
646  // Compute the result as an OR of all of the individual component accesses.
647  llvm::Value *Res = 0;
648  for (unsigned i = 0, e = Info.getNumComponents(); i != e; ++i) {
649    const CGBitFieldInfo::AccessInfo &AI = Info.getComponent(i);
650
651    // Get the field pointer.
652    llvm::Value *Ptr = LV.getBitFieldBaseAddr();
653
654    // Only offset by the field index if used, so that incoming values are not
655    // required to be structures.
656    if (AI.FieldIndex)
657      Ptr = Builder.CreateStructGEP(Ptr, AI.FieldIndex, "bf.field");
658
659    // Offset by the byte offset, if used.
660    if (AI.FieldByteOffset) {
661      const llvm::Type *i8PTy = llvm::Type::getInt8PtrTy(VMContext);
662      Ptr = Builder.CreateBitCast(Ptr, i8PTy);
663      Ptr = Builder.CreateConstGEP1_32(Ptr, AI.FieldByteOffset,"bf.field.offs");
664    }
665
666    // Cast to the access type.
667    const llvm::Type *PTy = llvm::Type::getIntNPtrTy(VMContext, AI.AccessWidth,
668                                                    ExprType.getAddressSpace());
669    Ptr = Builder.CreateBitCast(Ptr, PTy);
670
671    // Perform the load.
672    llvm::LoadInst *Load = Builder.CreateLoad(Ptr, LV.isVolatileQualified());
673    if (AI.AccessAlignment)
674      Load->setAlignment(AI.AccessAlignment);
675
676    // Shift out unused low bits and mask out unused high bits.
677    llvm::Value *Val = Load;
678    if (AI.FieldBitStart)
679      Val = Builder.CreateLShr(Load, AI.FieldBitStart);
680    Val = Builder.CreateAnd(Val, llvm::APInt::getLowBitsSet(AI.AccessWidth,
681                                                            AI.TargetBitWidth),
682                            "bf.clear");
683
684    // Extend or truncate to the target size.
685    if (AI.AccessWidth < ResSizeInBits)
686      Val = Builder.CreateZExt(Val, ResLTy);
687    else if (AI.AccessWidth > ResSizeInBits)
688      Val = Builder.CreateTrunc(Val, ResLTy);
689
690    // Shift into place, and OR into the result.
691    if (AI.TargetBitOffset)
692      Val = Builder.CreateShl(Val, AI.TargetBitOffset);
693    Res = Res ? Builder.CreateOr(Res, Val) : Val;
694  }
695
696  // If the bit-field is signed, perform the sign-extension.
697  //
698  // FIXME: This can easily be folded into the load of the high bits, which
699  // could also eliminate the mask of high bits in some situations.
700  if (Info.isSigned()) {
701    unsigned ExtraBits = ResSizeInBits - Info.getSize();
702    if (ExtraBits)
703      Res = Builder.CreateAShr(Builder.CreateShl(Res, ExtraBits),
704                               ExtraBits, "bf.val.sext");
705  }
706
707  return RValue::get(Res);
708}
709
710RValue CodeGenFunction::EmitLoadOfPropertyRefLValue(LValue LV,
711                                                    QualType ExprType) {
712  return EmitObjCPropertyGet(LV.getPropertyRefExpr());
713}
714
715RValue CodeGenFunction::EmitLoadOfKVCRefLValue(LValue LV,
716                                               QualType ExprType) {
717  return EmitObjCPropertyGet(LV.getKVCRefExpr());
718}
719
720// If this is a reference to a subset of the elements of a vector, create an
721// appropriate shufflevector.
722RValue CodeGenFunction::EmitLoadOfExtVectorElementLValue(LValue LV,
723                                                         QualType ExprType) {
724  llvm::Value *Vec = Builder.CreateLoad(LV.getExtVectorAddr(),
725                                        LV.isVolatileQualified(), "tmp");
726
727  const llvm::Constant *Elts = LV.getExtVectorElts();
728
729  // If the result of the expression is a non-vector type, we must be extracting
730  // a single element.  Just codegen as an extractelement.
731  const VectorType *ExprVT = ExprType->getAs<VectorType>();
732  if (!ExprVT) {
733    unsigned InIdx = getAccessedFieldNo(0, Elts);
734    llvm::Value *Elt = llvm::ConstantInt::get(Int32Ty, InIdx);
735    return RValue::get(Builder.CreateExtractElement(Vec, Elt, "tmp"));
736  }
737
738  // Always use shuffle vector to try to retain the original program structure
739  unsigned NumResultElts = ExprVT->getNumElements();
740
741  llvm::SmallVector<llvm::Constant*, 4> Mask;
742  for (unsigned i = 0; i != NumResultElts; ++i) {
743    unsigned InIdx = getAccessedFieldNo(i, Elts);
744    Mask.push_back(llvm::ConstantInt::get(Int32Ty, InIdx));
745  }
746
747  llvm::Value *MaskV = llvm::ConstantVector::get(&Mask[0], Mask.size());
748  Vec = Builder.CreateShuffleVector(Vec,
749                                    llvm::UndefValue::get(Vec->getType()),
750                                    MaskV, "tmp");
751  return RValue::get(Vec);
752}
753
754
755
756/// EmitStoreThroughLValue - Store the specified rvalue into the specified
757/// lvalue, where both are guaranteed to the have the same type, and that type
758/// is 'Ty'.
759void CodeGenFunction::EmitStoreThroughLValue(RValue Src, LValue Dst,
760                                             QualType Ty) {
761  if (!Dst.isSimple()) {
762    if (Dst.isVectorElt()) {
763      // Read/modify/write the vector, inserting the new element.
764      llvm::Value *Vec = Builder.CreateLoad(Dst.getVectorAddr(),
765                                            Dst.isVolatileQualified(), "tmp");
766      Vec = Builder.CreateInsertElement(Vec, Src.getScalarVal(),
767                                        Dst.getVectorIdx(), "vecins");
768      Builder.CreateStore(Vec, Dst.getVectorAddr(),Dst.isVolatileQualified());
769      return;
770    }
771
772    // If this is an update of extended vector elements, insert them as
773    // appropriate.
774    if (Dst.isExtVectorElt())
775      return EmitStoreThroughExtVectorComponentLValue(Src, Dst, Ty);
776
777    if (Dst.isBitField())
778      return EmitStoreThroughBitfieldLValue(Src, Dst, Ty);
779
780    if (Dst.isPropertyRef())
781      return EmitStoreThroughPropertyRefLValue(Src, Dst, Ty);
782
783    assert(Dst.isKVCRef() && "Unknown LValue type");
784    return EmitStoreThroughKVCRefLValue(Src, Dst, Ty);
785  }
786
787  if (Dst.isObjCWeak() && !Dst.isNonGC()) {
788    // load of a __weak object.
789    llvm::Value *LvalueDst = Dst.getAddress();
790    llvm::Value *src = Src.getScalarVal();
791     CGM.getObjCRuntime().EmitObjCWeakAssign(*this, src, LvalueDst);
792    return;
793  }
794
795  if (Dst.isObjCStrong() && !Dst.isNonGC()) {
796    // load of a __strong object.
797    llvm::Value *LvalueDst = Dst.getAddress();
798    llvm::Value *src = Src.getScalarVal();
799    if (Dst.isObjCIvar()) {
800      assert(Dst.getBaseIvarExp() && "BaseIvarExp is NULL");
801      const llvm::Type *ResultType = ConvertType(getContext().LongTy);
802      llvm::Value *RHS = EmitScalarExpr(Dst.getBaseIvarExp());
803      llvm::Value *dst = RHS;
804      RHS = Builder.CreatePtrToInt(RHS, ResultType, "sub.ptr.rhs.cast");
805      llvm::Value *LHS =
806        Builder.CreatePtrToInt(LvalueDst, ResultType, "sub.ptr.lhs.cast");
807      llvm::Value *BytesBetween = Builder.CreateSub(LHS, RHS, "ivar.offset");
808      CGM.getObjCRuntime().EmitObjCIvarAssign(*this, src, dst,
809                                              BytesBetween);
810    } else if (Dst.isGlobalObjCRef())
811      CGM.getObjCRuntime().EmitObjCGlobalAssign(*this, src, LvalueDst);
812    else
813      CGM.getObjCRuntime().EmitObjCStrongCastAssign(*this, src, LvalueDst);
814    return;
815  }
816
817  assert(Src.isScalar() && "Can't emit an agg store with this method");
818  EmitStoreOfScalar(Src.getScalarVal(), Dst.getAddress(),
819                    Dst.isVolatileQualified(), Ty);
820}
821
822void CodeGenFunction::EmitStoreThroughBitfieldLValue(RValue Src, LValue Dst,
823                                                     QualType Ty,
824                                                     llvm::Value **Result) {
825  const CGBitFieldInfo &Info = Dst.getBitFieldInfo();
826
827  // Get the output type.
828  const llvm::Type *ResLTy = ConvertTypeForMem(Ty);
829  unsigned ResSizeInBits = CGM.getTargetData().getTypeSizeInBits(ResLTy);
830
831  // Get the source value, truncated to the width of the bit-field.
832  llvm::Value *SrcVal = Src.getScalarVal();
833
834  if (Ty->isBooleanType())
835    SrcVal = Builder.CreateIntCast(SrcVal, ResLTy, /*IsSigned=*/false);
836
837  SrcVal = Builder.CreateAnd(SrcVal, llvm::APInt::getLowBitsSet(ResSizeInBits,
838                                                                Info.getSize()),
839                             "bf.value");
840
841  // Return the new value of the bit-field, if requested.
842  if (Result) {
843    // Cast back to the proper type for result.
844    const llvm::Type *SrcTy = Src.getScalarVal()->getType();
845    llvm::Value *ReloadVal = Builder.CreateIntCast(SrcVal, SrcTy, false,
846                                                   "bf.reload.val");
847
848    // Sign extend if necessary.
849    if (Info.isSigned()) {
850      unsigned ExtraBits = ResSizeInBits - Info.getSize();
851      if (ExtraBits)
852        ReloadVal = Builder.CreateAShr(Builder.CreateShl(ReloadVal, ExtraBits),
853                                       ExtraBits, "bf.reload.sext");
854    }
855
856    *Result = ReloadVal;
857  }
858
859  // Iterate over the components, writing each piece to memory.
860  for (unsigned i = 0, e = Info.getNumComponents(); i != e; ++i) {
861    const CGBitFieldInfo::AccessInfo &AI = Info.getComponent(i);
862
863    // Get the field pointer.
864    llvm::Value *Ptr = Dst.getBitFieldBaseAddr();
865
866    // Only offset by the field index if used, so that incoming values are not
867    // required to be structures.
868    if (AI.FieldIndex)
869      Ptr = Builder.CreateStructGEP(Ptr, AI.FieldIndex, "bf.field");
870
871    // Offset by the byte offset, if used.
872    if (AI.FieldByteOffset) {
873      const llvm::Type *i8PTy = llvm::Type::getInt8PtrTy(VMContext);
874      Ptr = Builder.CreateBitCast(Ptr, i8PTy);
875      Ptr = Builder.CreateConstGEP1_32(Ptr, AI.FieldByteOffset,"bf.field.offs");
876    }
877
878    // Cast to the access type.
879    const llvm::Type *PTy = llvm::Type::getIntNPtrTy(VMContext, AI.AccessWidth,
880                                                     Ty.getAddressSpace());
881    Ptr = Builder.CreateBitCast(Ptr, PTy);
882
883    // Extract the piece of the bit-field value to write in this access, limited
884    // to the values that are part of this access.
885    llvm::Value *Val = SrcVal;
886    if (AI.TargetBitOffset)
887      Val = Builder.CreateLShr(Val, AI.TargetBitOffset);
888    Val = Builder.CreateAnd(Val, llvm::APInt::getLowBitsSet(ResSizeInBits,
889                                                            AI.TargetBitWidth));
890
891    // Extend or truncate to the access size.
892    const llvm::Type *AccessLTy =
893      llvm::Type::getIntNTy(VMContext, AI.AccessWidth);
894    if (ResSizeInBits < AI.AccessWidth)
895      Val = Builder.CreateZExt(Val, AccessLTy);
896    else if (ResSizeInBits > AI.AccessWidth)
897      Val = Builder.CreateTrunc(Val, AccessLTy);
898
899    // Shift into the position in memory.
900    if (AI.FieldBitStart)
901      Val = Builder.CreateShl(Val, AI.FieldBitStart);
902
903    // If necessary, load and OR in bits that are outside of the bit-field.
904    if (AI.TargetBitWidth != AI.AccessWidth) {
905      llvm::LoadInst *Load = Builder.CreateLoad(Ptr, Dst.isVolatileQualified());
906      if (AI.AccessAlignment)
907        Load->setAlignment(AI.AccessAlignment);
908
909      // Compute the mask for zeroing the bits that are part of the bit-field.
910      llvm::APInt InvMask =
911        ~llvm::APInt::getBitsSet(AI.AccessWidth, AI.FieldBitStart,
912                                 AI.FieldBitStart + AI.TargetBitWidth);
913
914      // Apply the mask and OR in to the value to write.
915      Val = Builder.CreateOr(Builder.CreateAnd(Load, InvMask), Val);
916    }
917
918    // Write the value.
919    llvm::StoreInst *Store = Builder.CreateStore(Val, Ptr,
920                                                 Dst.isVolatileQualified());
921    if (AI.AccessAlignment)
922      Store->setAlignment(AI.AccessAlignment);
923  }
924}
925
926void CodeGenFunction::EmitStoreThroughPropertyRefLValue(RValue Src,
927                                                        LValue Dst,
928                                                        QualType Ty) {
929  EmitObjCPropertySet(Dst.getPropertyRefExpr(), Src);
930}
931
932void CodeGenFunction::EmitStoreThroughKVCRefLValue(RValue Src,
933                                                   LValue Dst,
934                                                   QualType Ty) {
935  EmitObjCPropertySet(Dst.getKVCRefExpr(), Src);
936}
937
938void CodeGenFunction::EmitStoreThroughExtVectorComponentLValue(RValue Src,
939                                                               LValue Dst,
940                                                               QualType Ty) {
941  // This access turns into a read/modify/write of the vector.  Load the input
942  // value now.
943  llvm::Value *Vec = Builder.CreateLoad(Dst.getExtVectorAddr(),
944                                        Dst.isVolatileQualified(), "tmp");
945  const llvm::Constant *Elts = Dst.getExtVectorElts();
946
947  llvm::Value *SrcVal = Src.getScalarVal();
948
949  if (const VectorType *VTy = Ty->getAs<VectorType>()) {
950    unsigned NumSrcElts = VTy->getNumElements();
951    unsigned NumDstElts =
952       cast<llvm::VectorType>(Vec->getType())->getNumElements();
953    if (NumDstElts == NumSrcElts) {
954      // Use shuffle vector is the src and destination are the same number of
955      // elements and restore the vector mask since it is on the side it will be
956      // stored.
957      llvm::SmallVector<llvm::Constant*, 4> Mask(NumDstElts);
958      for (unsigned i = 0; i != NumSrcElts; ++i) {
959        unsigned InIdx = getAccessedFieldNo(i, Elts);
960        Mask[InIdx] = llvm::ConstantInt::get(Int32Ty, i);
961      }
962
963      llvm::Value *MaskV = llvm::ConstantVector::get(&Mask[0], Mask.size());
964      Vec = Builder.CreateShuffleVector(SrcVal,
965                                        llvm::UndefValue::get(Vec->getType()),
966                                        MaskV, "tmp");
967    } else if (NumDstElts > NumSrcElts) {
968      // Extended the source vector to the same length and then shuffle it
969      // into the destination.
970      // FIXME: since we're shuffling with undef, can we just use the indices
971      //        into that?  This could be simpler.
972      llvm::SmallVector<llvm::Constant*, 4> ExtMask;
973      unsigned i;
974      for (i = 0; i != NumSrcElts; ++i)
975        ExtMask.push_back(llvm::ConstantInt::get(Int32Ty, i));
976      for (; i != NumDstElts; ++i)
977        ExtMask.push_back(llvm::UndefValue::get(Int32Ty));
978      llvm::Value *ExtMaskV = llvm::ConstantVector::get(&ExtMask[0],
979                                                        ExtMask.size());
980      llvm::Value *ExtSrcVal =
981        Builder.CreateShuffleVector(SrcVal,
982                                    llvm::UndefValue::get(SrcVal->getType()),
983                                    ExtMaskV, "tmp");
984      // build identity
985      llvm::SmallVector<llvm::Constant*, 4> Mask;
986      for (unsigned i = 0; i != NumDstElts; ++i)
987        Mask.push_back(llvm::ConstantInt::get(Int32Ty, i));
988
989      // modify when what gets shuffled in
990      for (unsigned i = 0; i != NumSrcElts; ++i) {
991        unsigned Idx = getAccessedFieldNo(i, Elts);
992        Mask[Idx] = llvm::ConstantInt::get(Int32Ty, i+NumDstElts);
993      }
994      llvm::Value *MaskV = llvm::ConstantVector::get(&Mask[0], Mask.size());
995      Vec = Builder.CreateShuffleVector(Vec, ExtSrcVal, MaskV, "tmp");
996    } else {
997      // We should never shorten the vector
998      assert(0 && "unexpected shorten vector length");
999    }
1000  } else {
1001    // If the Src is a scalar (not a vector) it must be updating one element.
1002    unsigned InIdx = getAccessedFieldNo(0, Elts);
1003    llvm::Value *Elt = llvm::ConstantInt::get(Int32Ty, InIdx);
1004    Vec = Builder.CreateInsertElement(Vec, SrcVal, Elt, "tmp");
1005  }
1006
1007  Builder.CreateStore(Vec, Dst.getExtVectorAddr(), Dst.isVolatileQualified());
1008}
1009
1010// setObjCGCLValueClass - sets class of he lvalue for the purpose of
1011// generating write-barries API. It is currently a global, ivar,
1012// or neither.
1013static void setObjCGCLValueClass(const ASTContext &Ctx, const Expr *E,
1014                                 LValue &LV) {
1015  if (Ctx.getLangOptions().getGCMode() == LangOptions::NonGC)
1016    return;
1017
1018  if (isa<ObjCIvarRefExpr>(E)) {
1019    LV.SetObjCIvar(LV, true);
1020    ObjCIvarRefExpr *Exp = cast<ObjCIvarRefExpr>(const_cast<Expr*>(E));
1021    LV.setBaseIvarExp(Exp->getBase());
1022    LV.SetObjCArray(LV, E->getType()->isArrayType());
1023    return;
1024  }
1025
1026  if (const DeclRefExpr *Exp = dyn_cast<DeclRefExpr>(E)) {
1027    if (const VarDecl *VD = dyn_cast<VarDecl>(Exp->getDecl())) {
1028      if ((VD->isBlockVarDecl() && !VD->hasLocalStorage()) ||
1029          VD->isFileVarDecl())
1030        LV.SetGlobalObjCRef(LV, true);
1031    }
1032    LV.SetObjCArray(LV, E->getType()->isArrayType());
1033    return;
1034  }
1035
1036  if (const UnaryOperator *Exp = dyn_cast<UnaryOperator>(E)) {
1037    setObjCGCLValueClass(Ctx, Exp->getSubExpr(), LV);
1038    return;
1039  }
1040
1041  if (const ParenExpr *Exp = dyn_cast<ParenExpr>(E)) {
1042    setObjCGCLValueClass(Ctx, Exp->getSubExpr(), LV);
1043    if (LV.isObjCIvar()) {
1044      // If cast is to a structure pointer, follow gcc's behavior and make it
1045      // a non-ivar write-barrier.
1046      QualType ExpTy = E->getType();
1047      if (ExpTy->isPointerType())
1048        ExpTy = ExpTy->getAs<PointerType>()->getPointeeType();
1049      if (ExpTy->isRecordType())
1050        LV.SetObjCIvar(LV, false);
1051    }
1052    return;
1053  }
1054  if (const ImplicitCastExpr *Exp = dyn_cast<ImplicitCastExpr>(E)) {
1055    setObjCGCLValueClass(Ctx, Exp->getSubExpr(), LV);
1056    return;
1057  }
1058
1059  if (const CStyleCastExpr *Exp = dyn_cast<CStyleCastExpr>(E)) {
1060    setObjCGCLValueClass(Ctx, Exp->getSubExpr(), LV);
1061    return;
1062  }
1063
1064  if (const ArraySubscriptExpr *Exp = dyn_cast<ArraySubscriptExpr>(E)) {
1065    setObjCGCLValueClass(Ctx, Exp->getBase(), LV);
1066    if (LV.isObjCIvar() && !LV.isObjCArray())
1067      // Using array syntax to assigning to what an ivar points to is not
1068      // same as assigning to the ivar itself. {id *Names;} Names[i] = 0;
1069      LV.SetObjCIvar(LV, false);
1070    else if (LV.isGlobalObjCRef() && !LV.isObjCArray())
1071      // Using array syntax to assigning to what global points to is not
1072      // same as assigning to the global itself. {id *G;} G[i] = 0;
1073      LV.SetGlobalObjCRef(LV, false);
1074    return;
1075  }
1076
1077  if (const MemberExpr *Exp = dyn_cast<MemberExpr>(E)) {
1078    setObjCGCLValueClass(Ctx, Exp->getBase(), LV);
1079    // We don't know if member is an 'ivar', but this flag is looked at
1080    // only in the context of LV.isObjCIvar().
1081    LV.SetObjCArray(LV, E->getType()->isArrayType());
1082    return;
1083  }
1084}
1085
1086static LValue EmitGlobalVarDeclLValue(CodeGenFunction &CGF,
1087                                      const Expr *E, const VarDecl *VD) {
1088  assert((VD->hasExternalStorage() || VD->isFileVarDecl()) &&
1089         "Var decl must have external storage or be a file var decl!");
1090
1091  llvm::Value *V = CGF.CGM.GetAddrOfGlobalVar(VD);
1092  if (VD->getType()->isReferenceType())
1093    V = CGF.Builder.CreateLoad(V, "tmp");
1094  LValue LV = LValue::MakeAddr(V, CGF.MakeQualifiers(E->getType()));
1095  setObjCGCLValueClass(CGF.getContext(), E, LV);
1096  return LV;
1097}
1098
1099static LValue EmitFunctionDeclLValue(CodeGenFunction &CGF,
1100                                      const Expr *E, const FunctionDecl *FD) {
1101  llvm::Value* V = CGF.CGM.GetAddrOfFunction(FD);
1102  if (!FD->hasPrototype()) {
1103    if (const FunctionProtoType *Proto =
1104            FD->getType()->getAs<FunctionProtoType>()) {
1105      // Ugly case: for a K&R-style definition, the type of the definition
1106      // isn't the same as the type of a use.  Correct for this with a
1107      // bitcast.
1108      QualType NoProtoType =
1109          CGF.getContext().getFunctionNoProtoType(Proto->getResultType());
1110      NoProtoType = CGF.getContext().getPointerType(NoProtoType);
1111      V = CGF.Builder.CreateBitCast(V, CGF.ConvertType(NoProtoType), "tmp");
1112    }
1113  }
1114  return LValue::MakeAddr(V, CGF.MakeQualifiers(E->getType()));
1115}
1116
1117LValue CodeGenFunction::EmitDeclRefLValue(const DeclRefExpr *E) {
1118  const NamedDecl *ND = E->getDecl();
1119
1120  if (ND->hasAttr<WeakRefAttr>()) {
1121    const ValueDecl* VD = cast<ValueDecl>(ND);
1122    llvm::Constant *Aliasee = CGM.GetWeakRefReference(VD);
1123
1124    Qualifiers Quals = MakeQualifiers(E->getType());
1125    LValue LV = LValue::MakeAddr(Aliasee, Quals);
1126
1127    return LV;
1128  }
1129
1130  if (const VarDecl *VD = dyn_cast<VarDecl>(ND)) {
1131
1132    // Check if this is a global variable.
1133    if (VD->hasExternalStorage() || VD->isFileVarDecl())
1134      return EmitGlobalVarDeclLValue(*this, E, VD);
1135
1136    bool NonGCable = VD->hasLocalStorage() && !VD->hasAttr<BlocksAttr>();
1137
1138    llvm::Value *V = LocalDeclMap[VD];
1139    if (!V && getContext().getLangOptions().CPlusPlus &&
1140        VD->isStaticLocal())
1141      V = CGM.getStaticLocalDeclAddress(VD);
1142    assert(V && "DeclRefExpr not entered in LocalDeclMap?");
1143
1144    Qualifiers Quals = MakeQualifiers(E->getType());
1145    // local variables do not get their gc attribute set.
1146    // local static?
1147    if (NonGCable) Quals.removeObjCGCAttr();
1148
1149    if (VD->hasAttr<BlocksAttr>()) {
1150      V = Builder.CreateStructGEP(V, 1, "forwarding");
1151      V = Builder.CreateLoad(V);
1152      V = Builder.CreateStructGEP(V, getByRefValueLLVMField(VD),
1153                                  VD->getNameAsString());
1154    }
1155    if (VD->getType()->isReferenceType())
1156      V = Builder.CreateLoad(V, "tmp");
1157    LValue LV = LValue::MakeAddr(V, Quals);
1158    LValue::SetObjCNonGC(LV, NonGCable);
1159    setObjCGCLValueClass(getContext(), E, LV);
1160    return LV;
1161  }
1162
1163  if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(ND))
1164    return EmitFunctionDeclLValue(*this, E, FD);
1165
1166  // FIXME: the qualifier check does not seem sufficient here
1167  if (E->getQualifier()) {
1168    const FieldDecl *FD = cast<FieldDecl>(ND);
1169    llvm::Value *V = CGM.EmitPointerToDataMember(FD);
1170
1171    return LValue::MakeAddr(V, MakeQualifiers(FD->getType()));
1172  }
1173
1174  assert(false && "Unhandled DeclRefExpr");
1175
1176  // an invalid LValue, but the assert will
1177  // ensure that this point is never reached.
1178  return LValue();
1179}
1180
1181LValue CodeGenFunction::EmitBlockDeclRefLValue(const BlockDeclRefExpr *E) {
1182  return LValue::MakeAddr(GetAddrOfBlockDecl(E), MakeQualifiers(E->getType()));
1183}
1184
1185LValue CodeGenFunction::EmitUnaryOpLValue(const UnaryOperator *E) {
1186  // __extension__ doesn't affect lvalue-ness.
1187  if (E->getOpcode() == UnaryOperator::Extension)
1188    return EmitLValue(E->getSubExpr());
1189
1190  QualType ExprTy = getContext().getCanonicalType(E->getSubExpr()->getType());
1191  switch (E->getOpcode()) {
1192  default: assert(0 && "Unknown unary operator lvalue!");
1193  case UnaryOperator::Deref: {
1194    QualType T = E->getSubExpr()->getType()->getPointeeType();
1195    assert(!T.isNull() && "CodeGenFunction::EmitUnaryOpLValue: Illegal type");
1196
1197    Qualifiers Quals = MakeQualifiers(T);
1198    Quals.setAddressSpace(ExprTy.getAddressSpace());
1199
1200    LValue LV = LValue::MakeAddr(EmitScalarExpr(E->getSubExpr()), Quals);
1201    // We should not generate __weak write barrier on indirect reference
1202    // of a pointer to object; as in void foo (__weak id *param); *param = 0;
1203    // But, we continue to generate __strong write barrier on indirect write
1204    // into a pointer to object.
1205    if (getContext().getLangOptions().ObjC1 &&
1206        getContext().getLangOptions().getGCMode() != LangOptions::NonGC &&
1207        LV.isObjCWeak())
1208      LValue::SetObjCNonGC(LV, !E->isOBJCGCCandidate(getContext()));
1209    return LV;
1210  }
1211  case UnaryOperator::Real:
1212  case UnaryOperator::Imag: {
1213    LValue LV = EmitLValue(E->getSubExpr());
1214    unsigned Idx = E->getOpcode() == UnaryOperator::Imag;
1215    return LValue::MakeAddr(Builder.CreateStructGEP(LV.getAddress(),
1216                                                    Idx, "idx"),
1217                            MakeQualifiers(ExprTy));
1218  }
1219  case UnaryOperator::PreInc:
1220  case UnaryOperator::PreDec: {
1221    LValue LV = EmitLValue(E->getSubExpr());
1222    bool isInc = E->getOpcode() == UnaryOperator::PreInc;
1223
1224    if (E->getType()->isAnyComplexType())
1225      EmitComplexPrePostIncDec(E, LV, isInc, true/*isPre*/);
1226    else
1227      EmitScalarPrePostIncDec(E, LV, isInc, true/*isPre*/);
1228    return LV;
1229  }
1230  }
1231}
1232
1233LValue CodeGenFunction::EmitStringLiteralLValue(const StringLiteral *E) {
1234  return LValue::MakeAddr(CGM.GetAddrOfConstantStringFromLiteral(E),
1235                          Qualifiers());
1236}
1237
1238LValue CodeGenFunction::EmitObjCEncodeExprLValue(const ObjCEncodeExpr *E) {
1239  return LValue::MakeAddr(CGM.GetAddrOfConstantStringFromObjCEncode(E),
1240                          Qualifiers());
1241}
1242
1243
1244LValue CodeGenFunction::EmitPredefinedFunctionName(unsigned Type) {
1245  std::string GlobalVarName;
1246
1247  switch (Type) {
1248  default: assert(0 && "Invalid type");
1249  case PredefinedExpr::Func:
1250    GlobalVarName = "__func__.";
1251    break;
1252  case PredefinedExpr::Function:
1253    GlobalVarName = "__FUNCTION__.";
1254    break;
1255  case PredefinedExpr::PrettyFunction:
1256    GlobalVarName = "__PRETTY_FUNCTION__.";
1257    break;
1258  }
1259
1260  llvm::StringRef FnName = CurFn->getName();
1261  if (FnName.startswith("\01"))
1262    FnName = FnName.substr(1);
1263  GlobalVarName += FnName;
1264
1265  std::string FunctionName =
1266    PredefinedExpr::ComputeName((PredefinedExpr::IdentType)Type, CurCodeDecl);
1267
1268  llvm::Constant *C =
1269    CGM.GetAddrOfConstantCString(FunctionName, GlobalVarName.c_str());
1270  return LValue::MakeAddr(C, Qualifiers());
1271}
1272
1273LValue CodeGenFunction::EmitPredefinedLValue(const PredefinedExpr *E) {
1274  switch (E->getIdentType()) {
1275  default:
1276    return EmitUnsupportedLValue(E, "predefined expression");
1277  case PredefinedExpr::Func:
1278  case PredefinedExpr::Function:
1279  case PredefinedExpr::PrettyFunction:
1280    return EmitPredefinedFunctionName(E->getIdentType());
1281  }
1282}
1283
1284llvm::BasicBlock *CodeGenFunction::getTrapBB() {
1285  const CodeGenOptions &GCO = CGM.getCodeGenOpts();
1286
1287  // If we are not optimzing, don't collapse all calls to trap in the function
1288  // to the same call, that way, in the debugger they can see which operation
1289  // did in fact fail.  If we are optimizing, we collpase all call to trap down
1290  // to just one per function to save on codesize.
1291  if (GCO.OptimizationLevel
1292      && TrapBB)
1293    return TrapBB;
1294
1295  llvm::BasicBlock *Cont = 0;
1296  if (HaveInsertPoint()) {
1297    Cont = createBasicBlock("cont");
1298    EmitBranch(Cont);
1299  }
1300  TrapBB = createBasicBlock("trap");
1301  EmitBlock(TrapBB);
1302
1303  llvm::Value *F = CGM.getIntrinsic(llvm::Intrinsic::trap, 0, 0);
1304  llvm::CallInst *TrapCall = Builder.CreateCall(F);
1305  TrapCall->setDoesNotReturn();
1306  TrapCall->setDoesNotThrow();
1307  Builder.CreateUnreachable();
1308
1309  if (Cont)
1310    EmitBlock(Cont);
1311  return TrapBB;
1312}
1313
1314/// isSimpleArrayDecayOperand - If the specified expr is a simple decay from an
1315/// array to pointer, return the array subexpression.
1316static const Expr *isSimpleArrayDecayOperand(const Expr *E) {
1317  // If this isn't just an array->pointer decay, bail out.
1318  const CastExpr *CE = dyn_cast<CastExpr>(E);
1319  if (CE == 0 || CE->getCastKind() != CastExpr::CK_ArrayToPointerDecay)
1320    return 0;
1321
1322  // If this is a decay from variable width array, bail out.
1323  const Expr *SubExpr = CE->getSubExpr();
1324  if (SubExpr->getType()->isVariableArrayType())
1325    return 0;
1326
1327  return SubExpr;
1328}
1329
1330LValue CodeGenFunction::EmitArraySubscriptExpr(const ArraySubscriptExpr *E) {
1331  // The index must always be an integer, which is not an aggregate.  Emit it.
1332  llvm::Value *Idx = EmitScalarExpr(E->getIdx());
1333  QualType IdxTy  = E->getIdx()->getType();
1334  bool IdxSigned = IdxTy->isSignedIntegerType();
1335
1336  // If the base is a vector type, then we are forming a vector element lvalue
1337  // with this subscript.
1338  if (E->getBase()->getType()->isVectorType()) {
1339    // Emit the vector as an lvalue to get its address.
1340    LValue LHS = EmitLValue(E->getBase());
1341    assert(LHS.isSimple() && "Can only subscript lvalue vectors here!");
1342    Idx = Builder.CreateIntCast(Idx, CGF.Int32Ty, IdxSigned, "vidx");
1343    return LValue::MakeVectorElt(LHS.getAddress(), Idx,
1344                                 E->getBase()->getType().getCVRQualifiers());
1345  }
1346
1347  // Extend or truncate the index type to 32 or 64-bits.
1348  if (!Idx->getType()->isIntegerTy(LLVMPointerWidth))
1349    Idx = Builder.CreateIntCast(Idx, IntPtrTy,
1350                                IdxSigned, "idxprom");
1351
1352  // FIXME: As llvm implements the object size checking, this can come out.
1353  if (CatchUndefined) {
1354    if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E->getBase())){
1355      if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(ICE->getSubExpr())) {
1356        if (ICE->getCastKind() == CastExpr::CK_ArrayToPointerDecay) {
1357          if (const ConstantArrayType *CAT
1358              = getContext().getAsConstantArrayType(DRE->getType())) {
1359            llvm::APInt Size = CAT->getSize();
1360            llvm::BasicBlock *Cont = createBasicBlock("cont");
1361            Builder.CreateCondBr(Builder.CreateICmpULE(Idx,
1362                                  llvm::ConstantInt::get(Idx->getType(), Size)),
1363                                 Cont, getTrapBB());
1364            EmitBlock(Cont);
1365          }
1366        }
1367      }
1368    }
1369  }
1370
1371  // We know that the pointer points to a type of the correct size, unless the
1372  // size is a VLA or Objective-C interface.
1373  llvm::Value *Address = 0;
1374  if (const VariableArrayType *VAT =
1375        getContext().getAsVariableArrayType(E->getType())) {
1376    llvm::Value *VLASize = GetVLASize(VAT);
1377
1378    Idx = Builder.CreateMul(Idx, VLASize);
1379
1380    QualType BaseType = getContext().getBaseElementType(VAT);
1381
1382    CharUnits BaseTypeSize = getContext().getTypeSizeInChars(BaseType);
1383    Idx = Builder.CreateUDiv(Idx,
1384                             llvm::ConstantInt::get(Idx->getType(),
1385                                 BaseTypeSize.getQuantity()));
1386
1387    // The base must be a pointer, which is not an aggregate.  Emit it.
1388    llvm::Value *Base = EmitScalarExpr(E->getBase());
1389
1390    Address = Builder.CreateInBoundsGEP(Base, Idx, "arrayidx");
1391  } else if (const ObjCObjectType *OIT = E->getType()->getAs<ObjCObjectType>()){
1392    // Indexing over an interface, as in "NSString *P; P[4];"
1393    llvm::Value *InterfaceSize =
1394      llvm::ConstantInt::get(Idx->getType(),
1395          getContext().getTypeSizeInChars(OIT).getQuantity());
1396
1397    Idx = Builder.CreateMul(Idx, InterfaceSize);
1398
1399    const llvm::Type *i8PTy = llvm::Type::getInt8PtrTy(VMContext);
1400
1401    // The base must be a pointer, which is not an aggregate.  Emit it.
1402    llvm::Value *Base = EmitScalarExpr(E->getBase());
1403    Address = Builder.CreateGEP(Builder.CreateBitCast(Base, i8PTy),
1404                                Idx, "arrayidx");
1405    Address = Builder.CreateBitCast(Address, Base->getType());
1406  } else if (const Expr *Array = isSimpleArrayDecayOperand(E->getBase())) {
1407    // If this is A[i] where A is an array, the frontend will have decayed the
1408    // base to be a ArrayToPointerDecay implicit cast.  While correct, it is
1409    // inefficient at -O0 to emit a "gep A, 0, 0" when codegen'ing it, then a
1410    // "gep x, i" here.  Emit one "gep A, 0, i".
1411    assert(Array->getType()->isArrayType() &&
1412           "Array to pointer decay must have array source type!");
1413    llvm::Value *ArrayPtr = EmitLValue(Array).getAddress();
1414    llvm::Value *Zero = llvm::ConstantInt::get(Int32Ty, 0);
1415    llvm::Value *Args[] = { Zero, Idx };
1416
1417    Address = Builder.CreateInBoundsGEP(ArrayPtr, Args, Args+2, "arrayidx");
1418  } else {
1419    // The base must be a pointer, which is not an aggregate.  Emit it.
1420    llvm::Value *Base = EmitScalarExpr(E->getBase());
1421    Address = Builder.CreateInBoundsGEP(Base, Idx, "arrayidx");
1422  }
1423
1424  QualType T = E->getBase()->getType()->getPointeeType();
1425  assert(!T.isNull() &&
1426         "CodeGenFunction::EmitArraySubscriptExpr(): Illegal base type");
1427
1428  Qualifiers Quals = MakeQualifiers(T);
1429  Quals.setAddressSpace(E->getBase()->getType().getAddressSpace());
1430
1431  LValue LV = LValue::MakeAddr(Address, Quals);
1432  if (getContext().getLangOptions().ObjC1 &&
1433      getContext().getLangOptions().getGCMode() != LangOptions::NonGC) {
1434    LValue::SetObjCNonGC(LV, !E->isOBJCGCCandidate(getContext()));
1435    setObjCGCLValueClass(getContext(), E, LV);
1436  }
1437  return LV;
1438}
1439
1440static
1441llvm::Constant *GenerateConstantVector(llvm::LLVMContext &VMContext,
1442                                       llvm::SmallVector<unsigned, 4> &Elts) {
1443  llvm::SmallVector<llvm::Constant*, 4> CElts;
1444
1445  const llvm::Type *Int32Ty = llvm::Type::getInt32Ty(VMContext);
1446  for (unsigned i = 0, e = Elts.size(); i != e; ++i)
1447    CElts.push_back(llvm::ConstantInt::get(Int32Ty, Elts[i]));
1448
1449  return llvm::ConstantVector::get(&CElts[0], CElts.size());
1450}
1451
1452LValue CodeGenFunction::
1453EmitExtVectorElementExpr(const ExtVectorElementExpr *E) {
1454  // Emit the base vector as an l-value.
1455  LValue Base;
1456
1457  // ExtVectorElementExpr's base can either be a vector or pointer to vector.
1458  if (E->isArrow()) {
1459    // If it is a pointer to a vector, emit the address and form an lvalue with
1460    // it.
1461    llvm::Value *Ptr = EmitScalarExpr(E->getBase());
1462    const PointerType *PT = E->getBase()->getType()->getAs<PointerType>();
1463    Qualifiers Quals = MakeQualifiers(PT->getPointeeType());
1464    Quals.removeObjCGCAttr();
1465    Base = LValue::MakeAddr(Ptr, Quals);
1466  } else if (E->getBase()->isLvalue(getContext()) == Expr::LV_Valid) {
1467    // Otherwise, if the base is an lvalue ( as in the case of foo.x.x),
1468    // emit the base as an lvalue.
1469    assert(E->getBase()->getType()->isVectorType());
1470    Base = EmitLValue(E->getBase());
1471  } else {
1472    // Otherwise, the base is a normal rvalue (as in (V+V).x), emit it as such.
1473    assert(E->getBase()->getType()->getAs<VectorType>() &&
1474           "Result must be a vector");
1475    llvm::Value *Vec = EmitScalarExpr(E->getBase());
1476
1477    // Store the vector to memory (because LValue wants an address).
1478    llvm::Value *VecMem = CreateMemTemp(E->getBase()->getType());
1479    Builder.CreateStore(Vec, VecMem);
1480    Base = LValue::MakeAddr(VecMem, Qualifiers());
1481  }
1482
1483  // Encode the element access list into a vector of unsigned indices.
1484  llvm::SmallVector<unsigned, 4> Indices;
1485  E->getEncodedElementAccess(Indices);
1486
1487  if (Base.isSimple()) {
1488    llvm::Constant *CV = GenerateConstantVector(VMContext, Indices);
1489    return LValue::MakeExtVectorElt(Base.getAddress(), CV,
1490                                    Base.getVRQualifiers());
1491  }
1492  assert(Base.isExtVectorElt() && "Can only subscript lvalue vec elts here!");
1493
1494  llvm::Constant *BaseElts = Base.getExtVectorElts();
1495  llvm::SmallVector<llvm::Constant *, 4> CElts;
1496
1497  for (unsigned i = 0, e = Indices.size(); i != e; ++i) {
1498    if (isa<llvm::ConstantAggregateZero>(BaseElts))
1499      CElts.push_back(llvm::ConstantInt::get(Int32Ty, 0));
1500    else
1501      CElts.push_back(cast<llvm::Constant>(BaseElts->getOperand(Indices[i])));
1502  }
1503  llvm::Constant *CV = llvm::ConstantVector::get(&CElts[0], CElts.size());
1504  return LValue::MakeExtVectorElt(Base.getExtVectorAddr(), CV,
1505                                  Base.getVRQualifiers());
1506}
1507
1508LValue CodeGenFunction::EmitMemberExpr(const MemberExpr *E) {
1509  bool isNonGC = false;
1510  Expr *BaseExpr = E->getBase();
1511  llvm::Value *BaseValue = NULL;
1512  Qualifiers BaseQuals;
1513
1514  // If this is s.x, emit s as an lvalue.  If it is s->x, emit s as a scalar.
1515  if (E->isArrow()) {
1516    BaseValue = EmitScalarExpr(BaseExpr);
1517    const PointerType *PTy =
1518      BaseExpr->getType()->getAs<PointerType>();
1519    BaseQuals = PTy->getPointeeType().getQualifiers();
1520  } else if (isa<ObjCPropertyRefExpr>(BaseExpr->IgnoreParens()) ||
1521             isa<ObjCImplicitSetterGetterRefExpr>(
1522               BaseExpr->IgnoreParens())) {
1523    RValue RV = EmitObjCPropertyGet(BaseExpr);
1524    BaseValue = RV.getAggregateAddr();
1525    BaseQuals = BaseExpr->getType().getQualifiers();
1526  } else {
1527    LValue BaseLV = EmitLValue(BaseExpr);
1528    if (BaseLV.isNonGC())
1529      isNonGC = true;
1530    // FIXME: this isn't right for bitfields.
1531    BaseValue = BaseLV.getAddress();
1532    QualType BaseTy = BaseExpr->getType();
1533    BaseQuals = BaseTy.getQualifiers();
1534  }
1535
1536  NamedDecl *ND = E->getMemberDecl();
1537  if (FieldDecl *Field = dyn_cast<FieldDecl>(ND)) {
1538    LValue LV = EmitLValueForField(BaseValue, Field,
1539                                   BaseQuals.getCVRQualifiers());
1540    LValue::SetObjCNonGC(LV, isNonGC);
1541    setObjCGCLValueClass(getContext(), E, LV);
1542    return LV;
1543  }
1544
1545  if (VarDecl *VD = dyn_cast<VarDecl>(ND))
1546    return EmitGlobalVarDeclLValue(*this, E, VD);
1547
1548  if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(ND))
1549    return EmitFunctionDeclLValue(*this, E, FD);
1550
1551  assert(false && "Unhandled member declaration!");
1552  return LValue();
1553}
1554
1555LValue CodeGenFunction::EmitLValueForBitfield(llvm::Value* BaseValue,
1556                                              const FieldDecl* Field,
1557                                              unsigned CVRQualifiers) {
1558  const CGRecordLayout &RL =
1559    CGM.getTypes().getCGRecordLayout(Field->getParent());
1560  const CGBitFieldInfo &Info = RL.getBitFieldInfo(Field);
1561  return LValue::MakeBitfield(BaseValue, Info,
1562                             Field->getType().getCVRQualifiers()|CVRQualifiers);
1563}
1564
1565/// EmitLValueForAnonRecordField - Given that the field is a member of
1566/// an anonymous struct or union buried inside a record, and given
1567/// that the base value is a pointer to the enclosing record, derive
1568/// an lvalue for the ultimate field.
1569LValue CodeGenFunction::EmitLValueForAnonRecordField(llvm::Value *BaseValue,
1570                                                     const FieldDecl *Field,
1571                                                     unsigned CVRQualifiers) {
1572  llvm::SmallVector<const FieldDecl *, 8> Path;
1573  Path.push_back(Field);
1574
1575  while (Field->getParent()->isAnonymousStructOrUnion()) {
1576    const ValueDecl *VD = Field->getParent()->getAnonymousStructOrUnionObject();
1577    if (!isa<FieldDecl>(VD)) break;
1578    Field = cast<FieldDecl>(VD);
1579    Path.push_back(Field);
1580  }
1581
1582  llvm::SmallVectorImpl<const FieldDecl*>::reverse_iterator
1583    I = Path.rbegin(), E = Path.rend();
1584  while (true) {
1585    LValue LV = EmitLValueForField(BaseValue, *I, CVRQualifiers);
1586    if (++I == E) return LV;
1587
1588    assert(LV.isSimple());
1589    BaseValue = LV.getAddress();
1590    CVRQualifiers |= LV.getVRQualifiers();
1591  }
1592}
1593
1594LValue CodeGenFunction::EmitLValueForField(llvm::Value* BaseValue,
1595                                           const FieldDecl* Field,
1596                                           unsigned CVRQualifiers) {
1597  if (Field->isBitField())
1598    return EmitLValueForBitfield(BaseValue, Field, CVRQualifiers);
1599
1600  const CGRecordLayout &RL =
1601    CGM.getTypes().getCGRecordLayout(Field->getParent());
1602  unsigned idx = RL.getLLVMFieldNo(Field);
1603  llvm::Value *V = Builder.CreateStructGEP(BaseValue, idx, "tmp");
1604
1605  // Match union field type.
1606  if (Field->getParent()->isUnion()) {
1607    const llvm::Type *FieldTy =
1608      CGM.getTypes().ConvertTypeForMem(Field->getType());
1609    const llvm::PointerType * BaseTy =
1610      cast<llvm::PointerType>(BaseValue->getType());
1611    unsigned AS = BaseTy->getAddressSpace();
1612    V = Builder.CreateBitCast(V,
1613                              llvm::PointerType::get(FieldTy, AS),
1614                              "tmp");
1615  }
1616  if (Field->getType()->isReferenceType())
1617    V = Builder.CreateLoad(V, "tmp");
1618
1619  Qualifiers Quals = MakeQualifiers(Field->getType());
1620  Quals.addCVRQualifiers(CVRQualifiers);
1621  // __weak attribute on a field is ignored.
1622  if (Quals.getObjCGCAttr() == Qualifiers::Weak)
1623    Quals.removeObjCGCAttr();
1624
1625  return LValue::MakeAddr(V, Quals);
1626}
1627
1628LValue
1629CodeGenFunction::EmitLValueForFieldInitialization(llvm::Value* BaseValue,
1630                                                  const FieldDecl* Field,
1631                                                  unsigned CVRQualifiers) {
1632  QualType FieldType = Field->getType();
1633
1634  if (!FieldType->isReferenceType())
1635    return EmitLValueForField(BaseValue, Field, CVRQualifiers);
1636
1637  const CGRecordLayout &RL =
1638    CGM.getTypes().getCGRecordLayout(Field->getParent());
1639  unsigned idx = RL.getLLVMFieldNo(Field);
1640  llvm::Value *V = Builder.CreateStructGEP(BaseValue, idx, "tmp");
1641
1642  assert(!FieldType.getObjCGCAttr() && "fields cannot have GC attrs");
1643
1644  return LValue::MakeAddr(V, MakeQualifiers(FieldType));
1645}
1646
1647LValue CodeGenFunction::EmitCompoundLiteralLValue(const CompoundLiteralExpr* E){
1648  llvm::Value *DeclPtr = CreateMemTemp(E->getType(), ".compoundliteral");
1649  const Expr* InitExpr = E->getInitializer();
1650  LValue Result = LValue::MakeAddr(DeclPtr, MakeQualifiers(E->getType()));
1651
1652  EmitAnyExprToMem(InitExpr, DeclPtr, /*Volatile*/ false);
1653
1654  return Result;
1655}
1656
1657LValue
1658CodeGenFunction::EmitConditionalOperatorLValue(const ConditionalOperator* E) {
1659  if (E->isLvalue(getContext()) == Expr::LV_Valid) {
1660    if (int Cond = ConstantFoldsToSimpleInteger(E->getCond())) {
1661      Expr *Live = Cond == 1 ? E->getLHS() : E->getRHS();
1662      if (Live)
1663        return EmitLValue(Live);
1664    }
1665
1666    if (!E->getLHS())
1667      return EmitUnsupportedLValue(E, "conditional operator with missing LHS");
1668
1669    llvm::BasicBlock *LHSBlock = createBasicBlock("cond.true");
1670    llvm::BasicBlock *RHSBlock = createBasicBlock("cond.false");
1671    llvm::BasicBlock *ContBlock = createBasicBlock("cond.end");
1672
1673    EmitBranchOnBoolExpr(E->getCond(), LHSBlock, RHSBlock);
1674
1675    // Any temporaries created here are conditional.
1676    BeginConditionalBranch();
1677    EmitBlock(LHSBlock);
1678    LValue LHS = EmitLValue(E->getLHS());
1679    EndConditionalBranch();
1680
1681    if (!LHS.isSimple())
1682      return EmitUnsupportedLValue(E, "conditional operator");
1683
1684    // FIXME: We shouldn't need an alloca for this.
1685    llvm::Value *Temp = CreateTempAlloca(LHS.getAddress()->getType(),"condtmp");
1686    Builder.CreateStore(LHS.getAddress(), Temp);
1687    EmitBranch(ContBlock);
1688
1689    // Any temporaries created here are conditional.
1690    BeginConditionalBranch();
1691    EmitBlock(RHSBlock);
1692    LValue RHS = EmitLValue(E->getRHS());
1693    EndConditionalBranch();
1694    if (!RHS.isSimple())
1695      return EmitUnsupportedLValue(E, "conditional operator");
1696
1697    Builder.CreateStore(RHS.getAddress(), Temp);
1698    EmitBranch(ContBlock);
1699
1700    EmitBlock(ContBlock);
1701
1702    Temp = Builder.CreateLoad(Temp, "lv");
1703    return LValue::MakeAddr(Temp, MakeQualifiers(E->getType()));
1704  }
1705
1706  // ?: here should be an aggregate.
1707  assert((hasAggregateLLVMType(E->getType()) &&
1708          !E->getType()->isAnyComplexType()) &&
1709         "Unexpected conditional operator!");
1710
1711  return EmitAggExprToLValue(E);
1712}
1713
1714/// EmitCastLValue - Casts are never lvalues unless that cast is a dynamic_cast.
1715/// If the cast is a dynamic_cast, we can have the usual lvalue result,
1716/// otherwise if a cast is needed by the code generator in an lvalue context,
1717/// then it must mean that we need the address of an aggregate in order to
1718/// access one of its fields.  This can happen for all the reasons that casts
1719/// are permitted with aggregate result, including noop aggregate casts, and
1720/// cast from scalar to union.
1721LValue CodeGenFunction::EmitCastLValue(const CastExpr *E) {
1722  switch (E->getCastKind()) {
1723  default:
1724    return EmitUnsupportedLValue(E, "unexpected cast lvalue");
1725
1726  case CastExpr::CK_Dynamic: {
1727    LValue LV = EmitLValue(E->getSubExpr());
1728    llvm::Value *V = LV.getAddress();
1729    const CXXDynamicCastExpr *DCE = cast<CXXDynamicCastExpr>(E);
1730    return LValue::MakeAddr(EmitDynamicCast(V, DCE),
1731                            MakeQualifiers(E->getType()));
1732  }
1733
1734  case CastExpr::CK_NoOp: {
1735    LValue LV = EmitLValue(E->getSubExpr());
1736    if (LV.isPropertyRef()) {
1737      QualType QT = E->getSubExpr()->getType();
1738      RValue RV = EmitLoadOfPropertyRefLValue(LV, QT);
1739      assert(!RV.isScalar() && "EmitCastLValue - scalar cast of property ref");
1740      llvm::Value *V = RV.getAggregateAddr();
1741      return LValue::MakeAddr(V, MakeQualifiers(QT));
1742    }
1743    return LV;
1744  }
1745  case CastExpr::CK_ConstructorConversion:
1746  case CastExpr::CK_UserDefinedConversion:
1747  case CastExpr::CK_AnyPointerToObjCPointerCast:
1748    return EmitLValue(E->getSubExpr());
1749
1750  case CastExpr::CK_UncheckedDerivedToBase:
1751  case CastExpr::CK_DerivedToBase: {
1752    const RecordType *DerivedClassTy =
1753      E->getSubExpr()->getType()->getAs<RecordType>();
1754    CXXRecordDecl *DerivedClassDecl =
1755      cast<CXXRecordDecl>(DerivedClassTy->getDecl());
1756
1757    LValue LV = EmitLValue(E->getSubExpr());
1758    llvm::Value *This;
1759    if (LV.isPropertyRef()) {
1760      RValue RV = EmitLoadOfPropertyRefLValue(LV, E->getSubExpr()->getType());
1761      assert (!RV.isScalar() && "EmitCastLValue");
1762      This = RV.getAggregateAddr();
1763    }
1764    else
1765      This = LV.getAddress();
1766
1767    // Perform the derived-to-base conversion
1768    llvm::Value *Base =
1769      GetAddressOfBaseClass(This, DerivedClassDecl,
1770                            E->getBasePath(), /*NullCheckValue=*/false);
1771
1772    return LValue::MakeAddr(Base, MakeQualifiers(E->getType()));
1773  }
1774  case CastExpr::CK_ToUnion:
1775    return EmitAggExprToLValue(E);
1776  case CastExpr::CK_BaseToDerived: {
1777    const RecordType *DerivedClassTy = E->getType()->getAs<RecordType>();
1778    CXXRecordDecl *DerivedClassDecl =
1779      cast<CXXRecordDecl>(DerivedClassTy->getDecl());
1780
1781    LValue LV = EmitLValue(E->getSubExpr());
1782
1783    // Perform the base-to-derived conversion
1784    llvm::Value *Derived =
1785      GetAddressOfDerivedClass(LV.getAddress(), DerivedClassDecl,
1786                               E->getBasePath(),/*NullCheckValue=*/false);
1787
1788    return LValue::MakeAddr(Derived, MakeQualifiers(E->getType()));
1789  }
1790  case CastExpr::CK_BitCast: {
1791    // This must be a reinterpret_cast (or c-style equivalent).
1792    const ExplicitCastExpr *CE = cast<ExplicitCastExpr>(E);
1793
1794    LValue LV = EmitLValue(E->getSubExpr());
1795    llvm::Value *V = Builder.CreateBitCast(LV.getAddress(),
1796                                           ConvertType(CE->getTypeAsWritten()));
1797    return LValue::MakeAddr(V, MakeQualifiers(E->getType()));
1798  }
1799  }
1800}
1801
1802LValue CodeGenFunction::EmitNullInitializationLValue(
1803                                              const CXXZeroInitValueExpr *E) {
1804  QualType Ty = E->getType();
1805  LValue LV = LValue::MakeAddr(CreateMemTemp(Ty), MakeQualifiers(Ty));
1806  EmitNullInitialization(LV.getAddress(), Ty);
1807  return LV;
1808}
1809
1810//===--------------------------------------------------------------------===//
1811//                             Expression Emission
1812//===--------------------------------------------------------------------===//
1813
1814
1815RValue CodeGenFunction::EmitCallExpr(const CallExpr *E,
1816                                     ReturnValueSlot ReturnValue) {
1817  // Builtins never have block type.
1818  if (E->getCallee()->getType()->isBlockPointerType())
1819    return EmitBlockCallExpr(E, ReturnValue);
1820
1821  if (const CXXMemberCallExpr *CE = dyn_cast<CXXMemberCallExpr>(E))
1822    return EmitCXXMemberCallExpr(CE, ReturnValue);
1823
1824  const Decl *TargetDecl = 0;
1825  if (const ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(E->getCallee())) {
1826    if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(CE->getSubExpr())) {
1827      TargetDecl = DRE->getDecl();
1828      if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(TargetDecl))
1829        if (unsigned builtinID = FD->getBuiltinID())
1830          return EmitBuiltinExpr(FD, builtinID, E);
1831    }
1832  }
1833
1834  if (const CXXOperatorCallExpr *CE = dyn_cast<CXXOperatorCallExpr>(E))
1835    if (const CXXMethodDecl *MD = dyn_cast_or_null<CXXMethodDecl>(TargetDecl))
1836      return EmitCXXOperatorMemberCallExpr(CE, MD, ReturnValue);
1837
1838  if (isa<CXXPseudoDestructorExpr>(E->getCallee()->IgnoreParens())) {
1839    // C++ [expr.pseudo]p1:
1840    //   The result shall only be used as the operand for the function call
1841    //   operator (), and the result of such a call has type void. The only
1842    //   effect is the evaluation of the postfix-expression before the dot or
1843    //   arrow.
1844    EmitScalarExpr(E->getCallee());
1845    return RValue::get(0);
1846  }
1847
1848  llvm::Value *Callee = EmitScalarExpr(E->getCallee());
1849  return EmitCall(E->getCallee()->getType(), Callee, ReturnValue,
1850                  E->arg_begin(), E->arg_end(), TargetDecl);
1851}
1852
1853LValue CodeGenFunction::EmitBinaryOperatorLValue(const BinaryOperator *E) {
1854  // Comma expressions just emit their LHS then their RHS as an l-value.
1855  if (E->getOpcode() == BinaryOperator::Comma) {
1856    EmitAnyExpr(E->getLHS());
1857    EnsureInsertPoint();
1858    return EmitLValue(E->getRHS());
1859  }
1860
1861  if (E->getOpcode() == BinaryOperator::PtrMemD ||
1862      E->getOpcode() == BinaryOperator::PtrMemI)
1863    return EmitPointerToDataMemberBinaryExpr(E);
1864
1865  // Can only get l-value for binary operator expressions which are a
1866  // simple assignment of aggregate type.
1867  if (E->getOpcode() != BinaryOperator::Assign)
1868    return EmitUnsupportedLValue(E, "binary l-value expression");
1869
1870  if (!hasAggregateLLVMType(E->getType())) {
1871    // Emit the LHS as an l-value.
1872    LValue LV = EmitLValue(E->getLHS());
1873
1874    llvm::Value *RHS = EmitScalarExpr(E->getRHS());
1875    EmitStoreOfScalar(RHS, LV.getAddress(), LV.isVolatileQualified(),
1876                      E->getType());
1877    return LV;
1878  }
1879
1880  return EmitAggExprToLValue(E);
1881}
1882
1883LValue CodeGenFunction::EmitCallExprLValue(const CallExpr *E) {
1884  RValue RV = EmitCallExpr(E);
1885
1886  if (!RV.isScalar())
1887    return LValue::MakeAddr(RV.getAggregateAddr(),MakeQualifiers(E->getType()));
1888
1889  assert(E->getCallReturnType()->isReferenceType() &&
1890         "Can't have a scalar return unless the return type is a "
1891         "reference type!");
1892
1893  return LValue::MakeAddr(RV.getScalarVal(), MakeQualifiers(E->getType()));
1894}
1895
1896LValue CodeGenFunction::EmitVAArgExprLValue(const VAArgExpr *E) {
1897  // FIXME: This shouldn't require another copy.
1898  return EmitAggExprToLValue(E);
1899}
1900
1901LValue CodeGenFunction::EmitCXXConstructLValue(const CXXConstructExpr *E) {
1902  llvm::Value *Temp = CreateMemTemp(E->getType(), "tmp");
1903  EmitCXXConstructExpr(Temp, E);
1904  return LValue::MakeAddr(Temp, MakeQualifiers(E->getType()));
1905}
1906
1907LValue
1908CodeGenFunction::EmitCXXTypeidLValue(const CXXTypeidExpr *E) {
1909  llvm::Value *Temp = EmitCXXTypeidExpr(E);
1910  return LValue::MakeAddr(Temp, MakeQualifiers(E->getType()));
1911}
1912
1913LValue
1914CodeGenFunction::EmitCXXBindTemporaryLValue(const CXXBindTemporaryExpr *E) {
1915  LValue LV = EmitLValue(E->getSubExpr());
1916  PushCXXTemporary(E->getTemporary(), LV.getAddress());
1917  return LV;
1918}
1919
1920LValue CodeGenFunction::EmitObjCMessageExprLValue(const ObjCMessageExpr *E) {
1921  RValue RV = EmitObjCMessageExpr(E);
1922
1923  if (!RV.isScalar())
1924    return LValue::MakeAddr(RV.getAggregateAddr(),
1925                            MakeQualifiers(E->getType()));
1926
1927  assert(E->getMethodDecl()->getResultType()->isReferenceType() &&
1928         "Can't have a scalar return unless the return type is a "
1929         "reference type!");
1930
1931  return LValue::MakeAddr(RV.getScalarVal(), MakeQualifiers(E->getType()));
1932}
1933
1934LValue CodeGenFunction::EmitObjCSelectorLValue(const ObjCSelectorExpr *E) {
1935  llvm::Value *V =
1936    CGM.getObjCRuntime().GetSelector(Builder, E->getSelector(), true);
1937  return LValue::MakeAddr(V, MakeQualifiers(E->getType()));
1938}
1939
1940llvm::Value *CodeGenFunction::EmitIvarOffset(const ObjCInterfaceDecl *Interface,
1941                                             const ObjCIvarDecl *Ivar) {
1942  return CGM.getObjCRuntime().EmitIvarOffset(*this, Interface, Ivar);
1943}
1944
1945LValue CodeGenFunction::EmitLValueForIvar(QualType ObjectTy,
1946                                          llvm::Value *BaseValue,
1947                                          const ObjCIvarDecl *Ivar,
1948                                          unsigned CVRQualifiers) {
1949  return CGM.getObjCRuntime().EmitObjCValueForIvar(*this, ObjectTy, BaseValue,
1950                                                   Ivar, CVRQualifiers);
1951}
1952
1953LValue CodeGenFunction::EmitObjCIvarRefLValue(const ObjCIvarRefExpr *E) {
1954  // FIXME: A lot of the code below could be shared with EmitMemberExpr.
1955  llvm::Value *BaseValue = 0;
1956  const Expr *BaseExpr = E->getBase();
1957  Qualifiers BaseQuals;
1958  QualType ObjectTy;
1959  if (E->isArrow()) {
1960    BaseValue = EmitScalarExpr(BaseExpr);
1961    ObjectTy = BaseExpr->getType()->getPointeeType();
1962    BaseQuals = ObjectTy.getQualifiers();
1963  } else {
1964    LValue BaseLV = EmitLValue(BaseExpr);
1965    // FIXME: this isn't right for bitfields.
1966    BaseValue = BaseLV.getAddress();
1967    ObjectTy = BaseExpr->getType();
1968    BaseQuals = ObjectTy.getQualifiers();
1969  }
1970
1971  LValue LV =
1972    EmitLValueForIvar(ObjectTy, BaseValue, E->getDecl(),
1973                      BaseQuals.getCVRQualifiers());
1974  setObjCGCLValueClass(getContext(), E, LV);
1975  return LV;
1976}
1977
1978LValue
1979CodeGenFunction::EmitObjCPropertyRefLValue(const ObjCPropertyRefExpr *E) {
1980  // This is a special l-value that just issues sends when we load or store
1981  // through it.
1982  return LValue::MakePropertyRef(E, E->getType().getCVRQualifiers());
1983}
1984
1985LValue CodeGenFunction::EmitObjCKVCRefLValue(
1986                                const ObjCImplicitSetterGetterRefExpr *E) {
1987  // This is a special l-value that just issues sends when we load or store
1988  // through it.
1989  return LValue::MakeKVCRef(E, E->getType().getCVRQualifiers());
1990}
1991
1992LValue CodeGenFunction::EmitObjCSuperExprLValue(const ObjCSuperExpr *E) {
1993  return EmitUnsupportedLValue(E, "use of super");
1994}
1995
1996LValue CodeGenFunction::EmitStmtExprLValue(const StmtExpr *E) {
1997  // Can only get l-value for message expression returning aggregate type
1998  RValue RV = EmitAnyExprToTemp(E);
1999  return LValue::MakeAddr(RV.getAggregateAddr(), MakeQualifiers(E->getType()));
2000}
2001
2002RValue CodeGenFunction::EmitCall(QualType CalleeType, llvm::Value *Callee,
2003                                 ReturnValueSlot ReturnValue,
2004                                 CallExpr::const_arg_iterator ArgBeg,
2005                                 CallExpr::const_arg_iterator ArgEnd,
2006                                 const Decl *TargetDecl) {
2007  // Get the actual function type. The callee type will always be a pointer to
2008  // function type or a block pointer type.
2009  assert(CalleeType->isFunctionPointerType() &&
2010         "Call must have function pointer type!");
2011
2012  CalleeType = getContext().getCanonicalType(CalleeType);
2013
2014  const FunctionType *FnType
2015    = cast<FunctionType>(cast<PointerType>(CalleeType)->getPointeeType());
2016  QualType ResultType = FnType->getResultType();
2017
2018  CallArgList Args;
2019  EmitCallArgs(Args, dyn_cast<FunctionProtoType>(FnType), ArgBeg, ArgEnd);
2020
2021  return EmitCall(CGM.getTypes().getFunctionInfo(Args, FnType),
2022                  Callee, ReturnValue, Args, TargetDecl);
2023}
2024
2025LValue CodeGenFunction::
2026EmitPointerToDataMemberBinaryExpr(const BinaryOperator *E) {
2027  llvm::Value *BaseV;
2028  if (E->getOpcode() == BinaryOperator::PtrMemI)
2029    BaseV = EmitScalarExpr(E->getLHS());
2030  else
2031    BaseV = EmitLValue(E->getLHS()).getAddress();
2032  const llvm::Type *i8Ty = llvm::Type::getInt8PtrTy(getLLVMContext());
2033  BaseV = Builder.CreateBitCast(BaseV, i8Ty);
2034  llvm::Value *OffsetV = EmitScalarExpr(E->getRHS());
2035  llvm::Value *AddV = Builder.CreateInBoundsGEP(BaseV, OffsetV, "add.ptr");
2036
2037  QualType Ty = E->getRHS()->getType();
2038  Ty = Ty->getAs<MemberPointerType>()->getPointeeType();
2039
2040  const llvm::Type *PType = ConvertType(getContext().getPointerType(Ty));
2041  AddV = Builder.CreateBitCast(AddV, PType);
2042  return LValue::MakeAddr(AddV, MakeQualifiers(Ty));
2043}
2044
2045