CGExpr.cpp revision 5db7ae59bb0115ccc420ff1d688abc8706559b57 
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  if (!hasAggregateLLVMType(E->getType()))
54    return RValue::get(EmitScalarExpr(E, IgnoreResult));
55  else if (E->getType()->isAnyComplexType())
56    return RValue::getComplex(EmitComplexExpr(E, false, false,
57                                              IgnoreResult, IgnoreResult));
58
59  EmitAggExpr(E, AggLoc, isAggLocVolatile, IgnoreResult);
60  return RValue::getAggregate(AggLoc, isAggLocVolatile);
61}
62
63/// EmitAnyExprToTemp - Similary to EmitAnyExpr(), however, the result
64/// will always be accessible even if no aggregate location is
65/// provided.
66RValue CodeGenFunction::EmitAnyExprToTemp(const Expr *E, llvm::Value *AggLoc,
67                                          bool isAggLocVolatile) {
68  if (!AggLoc && hasAggregateLLVMType(E->getType()) &&
69      !E->getType()->isAnyComplexType())
70    AggLoc = CreateTempAlloca(ConvertType(E->getType()), "agg.tmp");
71  return EmitAnyExpr(E, AggLoc, isAggLocVolatile);
72}
73
74RValue CodeGenFunction::EmitReferenceBindingToExpr(const Expr* E,
75                                                   QualType DestType) {
76  RValue Val;
77  if (E->isLvalue(getContext()) == Expr::LV_Valid) {
78    // Emit the expr as an lvalue.
79    LValue LV = EmitLValue(E);
80    if (LV.isSimple())
81      return RValue::get(LV.getAddress());
82    Val = EmitLoadOfLValue(LV, E->getType());
83  } else {
84    Val = EmitAnyExprToTemp(E);
85  }
86
87  if (Val.isAggregate()) {
88    Val = RValue::get(Val.getAggregateAddr());
89  } else {
90    // Create a temporary variable that we can bind the reference to.
91    llvm::Value *Temp = CreateTempAlloca(ConvertTypeForMem(E->getType()),
92                                         "reftmp");
93    if (Val.isScalar())
94      EmitStoreOfScalar(Val.getScalarVal(), Temp, false, E->getType());
95    else
96      StoreComplexToAddr(Val.getComplexVal(), Temp, false);
97    Val = RValue::get(Temp);
98  }
99
100  return Val;
101}
102
103
104/// getAccessedFieldNo - Given an encoded value and a result number, return
105/// the input field number being accessed.
106unsigned CodeGenFunction::getAccessedFieldNo(unsigned Idx,
107                                             const llvm::Constant *Elts) {
108  if (isa<llvm::ConstantAggregateZero>(Elts))
109    return 0;
110
111  return cast<llvm::ConstantInt>(Elts->getOperand(Idx))->getZExtValue();
112}
113
114
115//===----------------------------------------------------------------------===//
116//                         LValue Expression Emission
117//===----------------------------------------------------------------------===//
118
119RValue CodeGenFunction::GetUndefRValue(QualType Ty) {
120  if (Ty->isVoidType()) {
121    return RValue::get(0);
122  } else if (const ComplexType *CTy = Ty->getAsComplexType()) {
123    const llvm::Type *EltTy = ConvertType(CTy->getElementType());
124    llvm::Value *U = llvm::UndefValue::get(EltTy);
125    return RValue::getComplex(std::make_pair(U, U));
126  } else if (hasAggregateLLVMType(Ty)) {
127    const llvm::Type *LTy = llvm::PointerType::getUnqual(ConvertType(Ty));
128    return RValue::getAggregate(llvm::UndefValue::get(LTy));
129  } else {
130    return RValue::get(llvm::UndefValue::get(ConvertType(Ty)));
131  }
132}
133
134RValue CodeGenFunction::EmitUnsupportedRValue(const Expr *E,
135                                              const char *Name) {
136  ErrorUnsupported(E, Name);
137  return GetUndefRValue(E->getType());
138}
139
140LValue CodeGenFunction::EmitUnsupportedLValue(const Expr *E,
141                                              const char *Name) {
142  ErrorUnsupported(E, Name);
143  llvm::Type *Ty = llvm::PointerType::getUnqual(ConvertType(E->getType()));
144  return LValue::MakeAddr(llvm::UndefValue::get(Ty),
145                          E->getType().getCVRQualifiers(),
146                          getContext().getObjCGCAttrKind(E->getType()));
147}
148
149/// EmitLValue - Emit code to compute a designator that specifies the location
150/// of the expression.
151///
152/// This can return one of two things: a simple address or a bitfield
153/// reference.  In either case, the LLVM Value* in the LValue structure is
154/// guaranteed to be an LLVM pointer type.
155///
156/// If this returns a bitfield reference, nothing about the pointee type of
157/// the LLVM value is known: For example, it may not be a pointer to an
158/// integer.
159///
160/// If this returns a normal address, and if the lvalue's C type is fixed
161/// size, this method guarantees that the returned pointer type will point to
162/// an LLVM type of the same size of the lvalue's type.  If the lvalue has a
163/// variable length type, this is not possible.
164///
165LValue CodeGenFunction::EmitLValue(const Expr *E) {
166  switch (E->getStmtClass()) {
167  default: return EmitUnsupportedLValue(E, "l-value expression");
168
169  case Expr::BinaryOperatorClass:
170    return EmitBinaryOperatorLValue(cast<BinaryOperator>(E));
171  case Expr::CallExprClass:
172  case Expr::CXXOperatorCallExprClass:
173    return EmitCallExprLValue(cast<CallExpr>(E));
174  case Expr::VAArgExprClass:
175    return EmitVAArgExprLValue(cast<VAArgExpr>(E));
176  case Expr::DeclRefExprClass:
177  case Expr::QualifiedDeclRefExprClass:
178    return EmitDeclRefLValue(cast<DeclRefExpr>(E));
179  case Expr::ParenExprClass:return EmitLValue(cast<ParenExpr>(E)->getSubExpr());
180  case Expr::PredefinedExprClass:
181    return EmitPredefinedLValue(cast<PredefinedExpr>(E));
182  case Expr::StringLiteralClass:
183    return EmitStringLiteralLValue(cast<StringLiteral>(E));
184  case Expr::ObjCEncodeExprClass:
185    return EmitObjCEncodeExprLValue(cast<ObjCEncodeExpr>(E));
186
187  case Expr::BlockDeclRefExprClass:
188    return EmitBlockDeclRefLValue(cast<BlockDeclRefExpr>(E));
189
190  case Expr::CXXConditionDeclExprClass:
191    return EmitCXXConditionDeclLValue(cast<CXXConditionDeclExpr>(E));
192  case Expr::CXXTemporaryObjectExprClass:
193  case Expr::CXXConstructExprClass:
194    return EmitCXXConstructLValue(cast<CXXConstructExpr>(E));
195  case Expr::CXXBindTemporaryExprClass:
196    return EmitCXXBindTemporaryLValue(cast<CXXBindTemporaryExpr>(E));
197
198  case Expr::ObjCMessageExprClass:
199    return EmitObjCMessageExprLValue(cast<ObjCMessageExpr>(E));
200  case Expr::ObjCIvarRefExprClass:
201    return EmitObjCIvarRefLValue(cast<ObjCIvarRefExpr>(E));
202  case Expr::ObjCPropertyRefExprClass:
203    return EmitObjCPropertyRefLValue(cast<ObjCPropertyRefExpr>(E));
204  case Expr::ObjCKVCRefExprClass:
205    return EmitObjCKVCRefLValue(cast<ObjCKVCRefExpr>(E));
206  case Expr::ObjCSuperExprClass:
207    return EmitObjCSuperExprLValue(cast<ObjCSuperExpr>(E));
208
209  case Expr::StmtExprClass:
210    return EmitStmtExprLValue(cast<StmtExpr>(E));
211  case Expr::UnaryOperatorClass:
212    return EmitUnaryOpLValue(cast<UnaryOperator>(E));
213  case Expr::ArraySubscriptExprClass:
214    return EmitArraySubscriptExpr(cast<ArraySubscriptExpr>(E));
215  case Expr::ExtVectorElementExprClass:
216    return EmitExtVectorElementExpr(cast<ExtVectorElementExpr>(E));
217  case Expr::MemberExprClass: return EmitMemberExpr(cast<MemberExpr>(E));
218  case Expr::CompoundLiteralExprClass:
219    return EmitCompoundLiteralLValue(cast<CompoundLiteralExpr>(E));
220  case Expr::ConditionalOperatorClass:
221    return EmitConditionalOperator(cast<ConditionalOperator>(E));
222  case Expr::ChooseExprClass:
223    return EmitLValue(cast<ChooseExpr>(E)->getChosenSubExpr(getContext()));
224  case Expr::ImplicitCastExprClass:
225  case Expr::CStyleCastExprClass:
226  case Expr::CXXFunctionalCastExprClass:
227  case Expr::CXXStaticCastExprClass:
228  case Expr::CXXDynamicCastExprClass:
229  case Expr::CXXReinterpretCastExprClass:
230  case Expr::CXXConstCastExprClass:
231    return EmitCastLValue(cast<CastExpr>(E));
232  }
233}
234
235llvm::Value *CodeGenFunction::EmitLoadOfScalar(llvm::Value *Addr, bool Volatile,
236                                               QualType Ty) {
237  llvm::Value *V = Builder.CreateLoad(Addr, Volatile, "tmp");
238
239  // Bool can have different representation in memory than in registers.
240  if (Ty->isBooleanType())
241    if (V->getType() != llvm::Type::Int1Ty)
242      V = Builder.CreateTrunc(V, llvm::Type::Int1Ty, "tobool");
243
244  return V;
245}
246
247void CodeGenFunction::EmitStoreOfScalar(llvm::Value *Value, llvm::Value *Addr,
248                                        bool Volatile, QualType Ty) {
249
250  if (Ty->isBooleanType()) {
251    // Bool can have different representation in memory than in registers.
252    const llvm::Type *SrcTy = Value->getType();
253    const llvm::PointerType *DstPtr = cast<llvm::PointerType>(Addr->getType());
254    if (DstPtr->getElementType() != SrcTy) {
255      const llvm::Type *MemTy =
256        llvm::PointerType::get(SrcTy, DstPtr->getAddressSpace());
257      Addr = Builder.CreateBitCast(Addr, MemTy, "storetmp");
258    }
259  }
260
261  Builder.CreateStore(Value, Addr, Volatile);
262}
263
264/// EmitLoadOfLValue - Given an expression that represents a value lvalue,
265/// this method emits the address of the lvalue, then loads the result as an
266/// rvalue, returning the rvalue.
267RValue CodeGenFunction::EmitLoadOfLValue(LValue LV, QualType ExprType) {
268  if (LV.isObjCWeak()) {
269    // load of a __weak object.
270    llvm::Value *AddrWeakObj = LV.getAddress();
271    llvm::Value *read_weak = CGM.getObjCRuntime().EmitObjCWeakRead(*this,
272                                                                   AddrWeakObj);
273    return RValue::get(read_weak);
274  }
275
276  if (LV.isSimple()) {
277    llvm::Value *Ptr = LV.getAddress();
278    const llvm::Type *EltTy =
279      cast<llvm::PointerType>(Ptr->getType())->getElementType();
280
281    // Simple scalar l-value.
282    if (EltTy->isSingleValueType())
283      return RValue::get(EmitLoadOfScalar(Ptr, LV.isVolatileQualified(),
284                                          ExprType));
285
286    assert(ExprType->isFunctionType() && "Unknown scalar value");
287    return RValue::get(Ptr);
288  }
289
290  if (LV.isVectorElt()) {
291    llvm::Value *Vec = Builder.CreateLoad(LV.getVectorAddr(),
292                                          LV.isVolatileQualified(), "tmp");
293    return RValue::get(Builder.CreateExtractElement(Vec, LV.getVectorIdx(),
294                                                    "vecext"));
295  }
296
297  // If this is a reference to a subset of the elements of a vector, either
298  // shuffle the input or extract/insert them as appropriate.
299  if (LV.isExtVectorElt())
300    return EmitLoadOfExtVectorElementLValue(LV, ExprType);
301
302  if (LV.isBitfield())
303    return EmitLoadOfBitfieldLValue(LV, ExprType);
304
305  if (LV.isPropertyRef())
306    return EmitLoadOfPropertyRefLValue(LV, ExprType);
307
308  assert(LV.isKVCRef() && "Unknown LValue type!");
309  return EmitLoadOfKVCRefLValue(LV, ExprType);
310}
311
312RValue CodeGenFunction::EmitLoadOfBitfieldLValue(LValue LV,
313                                                 QualType ExprType) {
314  unsigned StartBit = LV.getBitfieldStartBit();
315  unsigned BitfieldSize = LV.getBitfieldSize();
316  llvm::Value *Ptr = LV.getBitfieldAddr();
317
318  const llvm::Type *EltTy =
319    cast<llvm::PointerType>(Ptr->getType())->getElementType();
320  unsigned EltTySize = CGM.getTargetData().getTypeSizeInBits(EltTy);
321
322  // In some cases the bitfield may straddle two memory locations.
323  // Currently we load the entire bitfield, then do the magic to
324  // sign-extend it if necessary. This results in somewhat more code
325  // than necessary for the common case (one load), since two shifts
326  // accomplish both the masking and sign extension.
327  unsigned LowBits = std::min(BitfieldSize, EltTySize - StartBit);
328  llvm::Value *Val = Builder.CreateLoad(Ptr, LV.isVolatileQualified(), "tmp");
329
330  // Shift to proper location.
331  if (StartBit)
332    Val = Builder.CreateLShr(Val, llvm::ConstantInt::get(EltTy, StartBit),
333                             "bf.lo");
334
335  // Mask off unused bits.
336  llvm::Constant *LowMask =
337    llvm::ConstantInt::get(llvm::APInt::getLowBitsSet(EltTySize, LowBits));
338  Val = Builder.CreateAnd(Val, LowMask, "bf.lo.cleared");
339
340  // Fetch the high bits if necessary.
341  if (LowBits < BitfieldSize) {
342    unsigned HighBits = BitfieldSize - LowBits;
343    llvm::Value *HighPtr =
344      Builder.CreateGEP(Ptr, llvm::ConstantInt::get(llvm::Type::Int32Ty, 1),
345                        "bf.ptr.hi");
346    llvm::Value *HighVal = Builder.CreateLoad(HighPtr,
347                                              LV.isVolatileQualified(),
348                                              "tmp");
349
350    // Mask off unused bits.
351    llvm::Constant *HighMask =
352      llvm::ConstantInt::get(llvm::APInt::getLowBitsSet(EltTySize, HighBits));
353    HighVal = Builder.CreateAnd(HighVal, HighMask, "bf.lo.cleared");
354
355    // Shift to proper location and or in to bitfield value.
356    HighVal = Builder.CreateShl(HighVal,
357                                llvm::ConstantInt::get(EltTy, LowBits));
358    Val = Builder.CreateOr(Val, HighVal, "bf.val");
359  }
360
361  // Sign extend if necessary.
362  if (LV.isBitfieldSigned()) {
363    llvm::Value *ExtraBits = llvm::ConstantInt::get(EltTy,
364                                                    EltTySize - BitfieldSize);
365    Val = Builder.CreateAShr(Builder.CreateShl(Val, ExtraBits),
366                             ExtraBits, "bf.val.sext");
367  }
368
369  // The bitfield type and the normal type differ when the storage sizes
370  // differ (currently just _Bool).
371  Val = Builder.CreateIntCast(Val, ConvertType(ExprType), false, "tmp");
372
373  return RValue::get(Val);
374}
375
376RValue CodeGenFunction::EmitLoadOfPropertyRefLValue(LValue LV,
377                                                    QualType ExprType) {
378  return EmitObjCPropertyGet(LV.getPropertyRefExpr());
379}
380
381RValue CodeGenFunction::EmitLoadOfKVCRefLValue(LValue LV,
382                                               QualType ExprType) {
383  return EmitObjCPropertyGet(LV.getKVCRefExpr());
384}
385
386// If this is a reference to a subset of the elements of a vector, create an
387// appropriate shufflevector.
388RValue CodeGenFunction::EmitLoadOfExtVectorElementLValue(LValue LV,
389                                                         QualType ExprType) {
390  llvm::Value *Vec = Builder.CreateLoad(LV.getExtVectorAddr(),
391                                        LV.isVolatileQualified(), "tmp");
392
393  const llvm::Constant *Elts = LV.getExtVectorElts();
394
395  // If the result of the expression is a non-vector type, we must be
396  // extracting a single element.  Just codegen as an extractelement.
397  const VectorType *ExprVT = ExprType->getAsVectorType();
398  if (!ExprVT) {
399    unsigned InIdx = getAccessedFieldNo(0, Elts);
400    llvm::Value *Elt = llvm::ConstantInt::get(llvm::Type::Int32Ty, InIdx);
401    return RValue::get(Builder.CreateExtractElement(Vec, Elt, "tmp"));
402  }
403
404  // Always use shuffle vector to try to retain the original program structure
405  unsigned NumResultElts = ExprVT->getNumElements();
406
407  llvm::SmallVector<llvm::Constant*, 4> Mask;
408  for (unsigned i = 0; i != NumResultElts; ++i) {
409    unsigned InIdx = getAccessedFieldNo(i, Elts);
410    Mask.push_back(llvm::ConstantInt::get(llvm::Type::Int32Ty, InIdx));
411  }
412
413  llvm::Value *MaskV = llvm::ConstantVector::get(&Mask[0], Mask.size());
414  Vec = Builder.CreateShuffleVector(Vec,
415                                    llvm::UndefValue::get(Vec->getType()),
416                                    MaskV, "tmp");
417  return RValue::get(Vec);
418}
419
420
421
422/// EmitStoreThroughLValue - Store the specified rvalue into the specified
423/// lvalue, where both are guaranteed to the have the same type, and that type
424/// is 'Ty'.
425void CodeGenFunction::EmitStoreThroughLValue(RValue Src, LValue Dst,
426                                             QualType Ty) {
427  if (!Dst.isSimple()) {
428    if (Dst.isVectorElt()) {
429      // Read/modify/write the vector, inserting the new element.
430      llvm::Value *Vec = Builder.CreateLoad(Dst.getVectorAddr(),
431                                            Dst.isVolatileQualified(), "tmp");
432      Vec = Builder.CreateInsertElement(Vec, Src.getScalarVal(),
433                                        Dst.getVectorIdx(), "vecins");
434      Builder.CreateStore(Vec, Dst.getVectorAddr(),Dst.isVolatileQualified());
435      return;
436    }
437
438    // If this is an update of extended vector elements, insert them as
439    // appropriate.
440    if (Dst.isExtVectorElt())
441      return EmitStoreThroughExtVectorComponentLValue(Src, Dst, Ty);
442
443    if (Dst.isBitfield())
444      return EmitStoreThroughBitfieldLValue(Src, Dst, Ty);
445
446    if (Dst.isPropertyRef())
447      return EmitStoreThroughPropertyRefLValue(Src, Dst, Ty);
448
449    if (Dst.isKVCRef())
450      return EmitStoreThroughKVCRefLValue(Src, Dst, Ty);
451
452    assert(0 && "Unknown LValue type");
453  }
454
455  if (Dst.isObjCWeak() && !Dst.isNonGC()) {
456    // load of a __weak object.
457    llvm::Value *LvalueDst = Dst.getAddress();
458    llvm::Value *src = Src.getScalarVal();
459     CGM.getObjCRuntime().EmitObjCWeakAssign(*this, src, LvalueDst);
460    return;
461  }
462
463  if (Dst.isObjCStrong() && !Dst.isNonGC()) {
464    // load of a __strong object.
465    llvm::Value *LvalueDst = Dst.getAddress();
466    llvm::Value *src = Src.getScalarVal();
467#if 0
468    // FIXME. We cannot positively determine if we have an 'ivar' assignment,
469    // object assignment or an unknown assignment. For now, generate call to
470    // objc_assign_strongCast assignment which is a safe, but consevative
471    // assumption.
472    if (Dst.isObjCIvar())
473      CGM.getObjCRuntime().EmitObjCIvarAssign(*this, src, LvalueDst);
474    else
475      CGM.getObjCRuntime().EmitObjCGlobalAssign(*this, src, LvalueDst);
476#endif
477    if (Dst.isGlobalObjCRef())
478      CGM.getObjCRuntime().EmitObjCGlobalAssign(*this, src, LvalueDst);
479    else
480      CGM.getObjCRuntime().EmitObjCStrongCastAssign(*this, src, LvalueDst);
481    return;
482  }
483
484  assert(Src.isScalar() && "Can't emit an agg store with this method");
485  EmitStoreOfScalar(Src.getScalarVal(), Dst.getAddress(),
486                    Dst.isVolatileQualified(), Ty);
487}
488
489void CodeGenFunction::EmitStoreThroughBitfieldLValue(RValue Src, LValue Dst,
490                                                     QualType Ty,
491                                                     llvm::Value **Result) {
492  unsigned StartBit = Dst.getBitfieldStartBit();
493  unsigned BitfieldSize = Dst.getBitfieldSize();
494  llvm::Value *Ptr = Dst.getBitfieldAddr();
495
496  const llvm::Type *EltTy =
497    cast<llvm::PointerType>(Ptr->getType())->getElementType();
498  unsigned EltTySize = CGM.getTargetData().getTypeSizeInBits(EltTy);
499
500  // Get the new value, cast to the appropriate type and masked to
501  // exactly the size of the bit-field.
502  llvm::Value *SrcVal = Src.getScalarVal();
503  llvm::Value *NewVal = Builder.CreateIntCast(SrcVal, EltTy, false, "tmp");
504  llvm::Constant *Mask =
505    llvm::ConstantInt::get(llvm::APInt::getLowBitsSet(EltTySize, BitfieldSize));
506  NewVal = Builder.CreateAnd(NewVal, Mask, "bf.value");
507
508  // Return the new value of the bit-field, if requested.
509  if (Result) {
510    // Cast back to the proper type for result.
511    const llvm::Type *SrcTy = SrcVal->getType();
512    llvm::Value *SrcTrunc = Builder.CreateIntCast(NewVal, SrcTy, false,
513                                                  "bf.reload.val");
514
515    // Sign extend if necessary.
516    if (Dst.isBitfieldSigned()) {
517      unsigned SrcTySize = CGM.getTargetData().getTypeSizeInBits(SrcTy);
518      llvm::Value *ExtraBits = llvm::ConstantInt::get(SrcTy,
519                                                      SrcTySize - BitfieldSize);
520      SrcTrunc = Builder.CreateAShr(Builder.CreateShl(SrcTrunc, ExtraBits),
521                                    ExtraBits, "bf.reload.sext");
522    }
523
524    *Result = SrcTrunc;
525  }
526
527  // In some cases the bitfield may straddle two memory locations.
528  // Emit the low part first and check to see if the high needs to be
529  // done.
530  unsigned LowBits = std::min(BitfieldSize, EltTySize - StartBit);
531  llvm::Value *LowVal = Builder.CreateLoad(Ptr, Dst.isVolatileQualified(),
532                                           "bf.prev.low");
533
534  // Compute the mask for zero-ing the low part of this bitfield.
535  llvm::Constant *InvMask =
536    llvm::ConstantInt::get(~llvm::APInt::getBitsSet(EltTySize, StartBit,
537                                                    StartBit + LowBits));
538
539  // Compute the new low part as
540  //   LowVal = (LowVal & InvMask) | (NewVal << StartBit),
541  // with the shift of NewVal implicitly stripping the high bits.
542  llvm::Value *NewLowVal =
543    Builder.CreateShl(NewVal, llvm::ConstantInt::get(EltTy, StartBit),
544                      "bf.value.lo");
545  LowVal = Builder.CreateAnd(LowVal, InvMask, "bf.prev.lo.cleared");
546  LowVal = Builder.CreateOr(LowVal, NewLowVal, "bf.new.lo");
547
548  // Write back.
549  Builder.CreateStore(LowVal, Ptr, Dst.isVolatileQualified());
550
551  // If the low part doesn't cover the bitfield emit a high part.
552  if (LowBits < BitfieldSize) {
553    unsigned HighBits = BitfieldSize - LowBits;
554    llvm::Value *HighPtr =
555      Builder.CreateGEP(Ptr, llvm::ConstantInt::get(llvm::Type::Int32Ty, 1),
556                        "bf.ptr.hi");
557    llvm::Value *HighVal = Builder.CreateLoad(HighPtr,
558                                              Dst.isVolatileQualified(),
559                                              "bf.prev.hi");
560
561    // Compute the mask for zero-ing the high part of this bitfield.
562    llvm::Constant *InvMask =
563      llvm::ConstantInt::get(~llvm::APInt::getLowBitsSet(EltTySize, HighBits));
564
565    // Compute the new high part as
566    //   HighVal = (HighVal & InvMask) | (NewVal lshr LowBits),
567    // where the high bits of NewVal have already been cleared and the
568    // shift stripping the low bits.
569    llvm::Value *NewHighVal =
570      Builder.CreateLShr(NewVal, llvm::ConstantInt::get(EltTy, LowBits),
571                        "bf.value.high");
572    HighVal = Builder.CreateAnd(HighVal, InvMask, "bf.prev.hi.cleared");
573    HighVal = Builder.CreateOr(HighVal, NewHighVal, "bf.new.hi");
574
575    // Write back.
576    Builder.CreateStore(HighVal, HighPtr, Dst.isVolatileQualified());
577  }
578}
579
580void CodeGenFunction::EmitStoreThroughPropertyRefLValue(RValue Src,
581                                                        LValue Dst,
582                                                        QualType Ty) {
583  EmitObjCPropertySet(Dst.getPropertyRefExpr(), Src);
584}
585
586void CodeGenFunction::EmitStoreThroughKVCRefLValue(RValue Src,
587                                                   LValue Dst,
588                                                   QualType Ty) {
589  EmitObjCPropertySet(Dst.getKVCRefExpr(), Src);
590}
591
592void CodeGenFunction::EmitStoreThroughExtVectorComponentLValue(RValue Src,
593                                                               LValue Dst,
594                                                               QualType Ty) {
595  // This access turns into a read/modify/write of the vector.  Load the input
596  // value now.
597  llvm::Value *Vec = Builder.CreateLoad(Dst.getExtVectorAddr(),
598                                        Dst.isVolatileQualified(), "tmp");
599  const llvm::Constant *Elts = Dst.getExtVectorElts();
600
601  llvm::Value *SrcVal = Src.getScalarVal();
602
603  if (const VectorType *VTy = Ty->getAsVectorType()) {
604    unsigned NumSrcElts = VTy->getNumElements();
605    unsigned NumDstElts =
606       cast<llvm::VectorType>(Vec->getType())->getNumElements();
607    if (NumDstElts == NumSrcElts) {
608      // Use shuffle vector is the src and destination are the same number
609      // of elements
610      llvm::SmallVector<llvm::Constant*, 4> Mask;
611      for (unsigned i = 0; i != NumSrcElts; ++i) {
612        unsigned InIdx = getAccessedFieldNo(i, Elts);
613        Mask.push_back(llvm::ConstantInt::get(llvm::Type::Int32Ty, InIdx));
614      }
615
616      llvm::Value *MaskV = llvm::ConstantVector::get(&Mask[0], Mask.size());
617      Vec = Builder.CreateShuffleVector(SrcVal,
618                                        llvm::UndefValue::get(Vec->getType()),
619                                        MaskV, "tmp");
620    }
621    else if (NumDstElts > NumSrcElts) {
622      // Extended the source vector to the same length and then shuffle it
623      // into the destination.
624      // FIXME: since we're shuffling with undef, can we just use the indices
625      //        into that?  This could be simpler.
626      llvm::SmallVector<llvm::Constant*, 4> ExtMask;
627      unsigned i;
628      for (i = 0; i != NumSrcElts; ++i)
629        ExtMask.push_back(llvm::ConstantInt::get(llvm::Type::Int32Ty, i));
630      for (; i != NumDstElts; ++i)
631        ExtMask.push_back(llvm::UndefValue::get(llvm::Type::Int32Ty));
632      llvm::Value *ExtMaskV = llvm::ConstantVector::get(&ExtMask[0],
633                                                        ExtMask.size());
634      llvm::Value *ExtSrcVal =
635        Builder.CreateShuffleVector(SrcVal,
636                                    llvm::UndefValue::get(SrcVal->getType()),
637                                    ExtMaskV, "tmp");
638      // build identity
639      llvm::SmallVector<llvm::Constant*, 4> Mask;
640      for (unsigned i = 0; i != NumDstElts; ++i) {
641        Mask.push_back(llvm::ConstantInt::get(llvm::Type::Int32Ty, i));
642      }
643      // modify when what gets shuffled in
644      for (unsigned i = 0; i != NumSrcElts; ++i) {
645        unsigned Idx = getAccessedFieldNo(i, Elts);
646        Mask[Idx] =llvm::ConstantInt::get(llvm::Type::Int32Ty, i+NumDstElts);
647      }
648      llvm::Value *MaskV = llvm::ConstantVector::get(&Mask[0], Mask.size());
649      Vec = Builder.CreateShuffleVector(Vec, ExtSrcVal, MaskV, "tmp");
650    }
651    else {
652      // We should never shorten the vector
653      assert(0 && "unexpected shorten vector length");
654    }
655  } else {
656    // If the Src is a scalar (not a vector) it must be updating one element.
657    unsigned InIdx = getAccessedFieldNo(0, Elts);
658    llvm::Value *Elt = llvm::ConstantInt::get(llvm::Type::Int32Ty, InIdx);
659    Vec = Builder.CreateInsertElement(Vec, SrcVal, Elt, "tmp");
660  }
661
662  Builder.CreateStore(Vec, Dst.getExtVectorAddr(), Dst.isVolatileQualified());
663}
664
665LValue CodeGenFunction::EmitDeclRefLValue(const DeclRefExpr *E) {
666  const VarDecl *VD = dyn_cast<VarDecl>(E->getDecl());
667
668  if (VD && (VD->isBlockVarDecl() || isa<ParmVarDecl>(VD) ||
669        isa<ImplicitParamDecl>(VD))) {
670    LValue LV;
671    bool NonGCable = VD->hasLocalStorage() && !VD->hasAttr<BlocksAttr>();
672    if (VD->hasExternalStorage()) {
673      llvm::Value *V = CGM.GetAddrOfGlobalVar(VD);
674      if (VD->getType()->isReferenceType())
675        V = Builder.CreateLoad(V, "tmp");
676      LV = LValue::MakeAddr(V, E->getType().getCVRQualifiers(),
677                            getContext().getObjCGCAttrKind(E->getType()));
678    }
679    else {
680      llvm::Value *V = LocalDeclMap[VD];
681      assert(V && "DeclRefExpr not entered in LocalDeclMap?");
682      // local variables do not get their gc attribute set.
683      QualType::GCAttrTypes attr = QualType::GCNone;
684      // local static?
685      if (!NonGCable)
686        attr = getContext().getObjCGCAttrKind(E->getType());
687      if (VD->hasAttr<BlocksAttr>()) {
688        bool needsCopyDispose = BlockRequiresCopying(VD->getType());
689        const llvm::Type *PtrStructTy = V->getType();
690        const llvm::Type *Ty = PtrStructTy;
691        Ty = llvm::PointerType::get(Ty, 0);
692        V = Builder.CreateStructGEP(V, 1, "forwarding");
693        V = Builder.CreateBitCast(V, Ty);
694        V = Builder.CreateLoad(V, false);
695        V = Builder.CreateBitCast(V, PtrStructTy);
696        V = Builder.CreateStructGEP(V, needsCopyDispose*2 + 4, "x");
697      }
698      if (VD->getType()->isReferenceType())
699        V = Builder.CreateLoad(V, "tmp");
700      LV = LValue::MakeAddr(V, E->getType().getCVRQualifiers(), attr);
701    }
702    LValue::SetObjCNonGC(LV, NonGCable);
703    return LV;
704  } else if (VD && VD->isFileVarDecl()) {
705    llvm::Value *V = CGM.GetAddrOfGlobalVar(VD);
706    if (VD->getType()->isReferenceType())
707      V = Builder.CreateLoad(V, "tmp");
708    LValue LV = LValue::MakeAddr(V, E->getType().getCVRQualifiers(),
709                                 getContext().getObjCGCAttrKind(E->getType()));
710    if (LV.isObjCStrong())
711      LV.SetGlobalObjCRef(LV, true);
712    return LV;
713  } else if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(E->getDecl())) {
714    llvm::Value* V = CGM.GetAddrOfFunction(GlobalDecl(FD));
715    if (!FD->hasPrototype()) {
716      if (const FunctionProtoType *Proto =
717              FD->getType()->getAsFunctionProtoType()) {
718        // Ugly case: for a K&R-style definition, the type of the definition
719        // isn't the same as the type of a use.  Correct for this with a
720        // bitcast.
721        QualType NoProtoType =
722            getContext().getFunctionNoProtoType(Proto->getResultType());
723        NoProtoType = getContext().getPointerType(NoProtoType);
724        V = Builder.CreateBitCast(V, ConvertType(NoProtoType), "tmp");
725      }
726    }
727    return LValue::MakeAddr(V, E->getType().getCVRQualifiers(),
728                            getContext().getObjCGCAttrKind(E->getType()));
729  }
730  else if (const ImplicitParamDecl *IPD =
731      dyn_cast<ImplicitParamDecl>(E->getDecl())) {
732    llvm::Value *V = LocalDeclMap[IPD];
733    assert(V && "BlockVarDecl not entered in LocalDeclMap?");
734    return LValue::MakeAddr(V, E->getType().getCVRQualifiers(),
735                            getContext().getObjCGCAttrKind(E->getType()));
736  }
737  assert(0 && "Unimp declref");
738  //an invalid LValue, but the assert will
739  //ensure that this point is never reached.
740  return LValue();
741}
742
743LValue CodeGenFunction::EmitBlockDeclRefLValue(const BlockDeclRefExpr *E) {
744  return LValue::MakeAddr(GetAddrOfBlockDecl(E),
745                          E->getType().getCVRQualifiers(),
746                          getContext().getObjCGCAttrKind(E->getType()));
747}
748
749LValue CodeGenFunction::EmitUnaryOpLValue(const UnaryOperator *E) {
750  // __extension__ doesn't affect lvalue-ness.
751  if (E->getOpcode() == UnaryOperator::Extension)
752    return EmitLValue(E->getSubExpr());
753
754  QualType ExprTy = getContext().getCanonicalType(E->getSubExpr()->getType());
755  switch (E->getOpcode()) {
756  default: assert(0 && "Unknown unary operator lvalue!");
757  case UnaryOperator::Deref:
758    {
759      QualType T =
760        E->getSubExpr()->getType()->getAsPointerType()->getPointeeType();
761      LValue LV = LValue::MakeAddr(EmitScalarExpr(E->getSubExpr()),
762                                   ExprTy->getAsPointerType()->getPointeeType()
763                                      .getCVRQualifiers(),
764                                   getContext().getObjCGCAttrKind(T));
765     // We should not generate __weak write barrier on indirect reference
766     // of a pointer to object; as in void foo (__weak id *param); *param = 0;
767     // But, we continue to generate __strong write barrier on indirect write
768     // into a pointer to object.
769     if (getContext().getLangOptions().ObjC1 &&
770         getContext().getLangOptions().getGCMode() != LangOptions::NonGC &&
771         LV.isObjCWeak())
772       LValue::SetObjCNonGC(LV, !E->isOBJCGCCandidate(getContext()));
773     return LV;
774    }
775  case UnaryOperator::Real:
776  case UnaryOperator::Imag:
777    LValue LV = EmitLValue(E->getSubExpr());
778    unsigned Idx = E->getOpcode() == UnaryOperator::Imag;
779    return LValue::MakeAddr(Builder.CreateStructGEP(LV.getAddress(),
780                                                    Idx, "idx"),
781                            ExprTy.getCVRQualifiers());
782  }
783}
784
785LValue CodeGenFunction::EmitStringLiteralLValue(const StringLiteral *E) {
786  return LValue::MakeAddr(CGM.GetAddrOfConstantStringFromLiteral(E), 0);
787}
788
789LValue CodeGenFunction::EmitObjCEncodeExprLValue(const ObjCEncodeExpr *E) {
790  return LValue::MakeAddr(CGM.GetAddrOfConstantStringFromObjCEncode(E), 0);
791}
792
793
794LValue CodeGenFunction::EmitPredefinedFunctionName(unsigned Type) {
795  std::string GlobalVarName;
796
797  switch (Type) {
798  default:
799    assert(0 && "Invalid type");
800  case PredefinedExpr::Func:
801    GlobalVarName = "__func__.";
802    break;
803  case PredefinedExpr::Function:
804    GlobalVarName = "__FUNCTION__.";
805    break;
806  case PredefinedExpr::PrettyFunction:
807    // FIXME:: Demangle C++ method names
808    GlobalVarName = "__PRETTY_FUNCTION__.";
809    break;
810  }
811
812  // FIXME: This isn't right at all.  The logic for computing this should go
813  // into a method on PredefinedExpr.  This would allow sema and codegen to be
814  // consistent for things like sizeof(__func__) etc.
815  std::string FunctionName;
816  if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(CurCodeDecl)) {
817    FunctionName = CGM.getMangledName(FD);
818  } else {
819    // Just get the mangled name; skipping the asm prefix if it
820    // exists.
821    FunctionName = CurFn->getName();
822    if (FunctionName[0] == '\01')
823      FunctionName = FunctionName.substr(1, std::string::npos);
824  }
825
826  GlobalVarName += FunctionName;
827  llvm::Constant *C =
828    CGM.GetAddrOfConstantCString(FunctionName, GlobalVarName.c_str());
829  return LValue::MakeAddr(C, 0);
830}
831
832LValue CodeGenFunction::EmitPredefinedLValue(const PredefinedExpr *E) {
833  switch (E->getIdentType()) {
834  default:
835    return EmitUnsupportedLValue(E, "predefined expression");
836  case PredefinedExpr::Func:
837  case PredefinedExpr::Function:
838  case PredefinedExpr::PrettyFunction:
839    return EmitPredefinedFunctionName(E->getIdentType());
840  }
841}
842
843LValue CodeGenFunction::EmitArraySubscriptExpr(const ArraySubscriptExpr *E) {
844  // The index must always be an integer, which is not an aggregate.  Emit it.
845  llvm::Value *Idx = EmitScalarExpr(E->getIdx());
846  QualType IdxTy  = E->getIdx()->getType();
847  bool IdxSigned = IdxTy->isSignedIntegerType();
848
849  // If the base is a vector type, then we are forming a vector element lvalue
850  // with this subscript.
851  if (E->getBase()->getType()->isVectorType()) {
852    // Emit the vector as an lvalue to get its address.
853    LValue LHS = EmitLValue(E->getBase());
854    assert(LHS.isSimple() && "Can only subscript lvalue vectors here!");
855    Idx = Builder.CreateIntCast(Idx, llvm::Type::Int32Ty, IdxSigned, "vidx");
856    return LValue::MakeVectorElt(LHS.getAddress(), Idx,
857      E->getBase()->getType().getCVRQualifiers());
858  }
859
860  // The base must be a pointer, which is not an aggregate.  Emit it.
861  llvm::Value *Base = EmitScalarExpr(E->getBase());
862
863  // Extend or truncate the index type to 32 or 64-bits.
864  unsigned IdxBitwidth = cast<llvm::IntegerType>(Idx->getType())->getBitWidth();
865  if (IdxBitwidth != LLVMPointerWidth)
866    Idx = Builder.CreateIntCast(Idx, llvm::IntegerType::get(LLVMPointerWidth),
867                                IdxSigned, "idxprom");
868
869  // We know that the pointer points to a type of the correct size,
870  // unless the size is a VLA or Objective-C interface.
871  llvm::Value *Address = 0;
872  if (const VariableArrayType *VAT =
873        getContext().getAsVariableArrayType(E->getType())) {
874    llvm::Value *VLASize = VLASizeMap[VAT];
875
876    Idx = Builder.CreateMul(Idx, VLASize);
877
878    QualType BaseType = getContext().getBaseElementType(VAT);
879
880    uint64_t BaseTypeSize = getContext().getTypeSize(BaseType) / 8;
881    Idx = Builder.CreateUDiv(Idx,
882                             llvm::ConstantInt::get(Idx->getType(),
883                                                    BaseTypeSize));
884    Address = Builder.CreateGEP(Base, Idx, "arrayidx");
885  } else if (const ObjCInterfaceType *OIT =
886             dyn_cast<ObjCInterfaceType>(E->getType())) {
887    llvm::Value *InterfaceSize =
888      llvm::ConstantInt::get(Idx->getType(),
889                             getContext().getTypeSize(OIT) / 8);
890
891    Idx = Builder.CreateMul(Idx, InterfaceSize);
892
893    llvm::Type *i8PTy = llvm::PointerType::getUnqual(llvm::Type::Int8Ty);
894    Address = Builder.CreateGEP(Builder.CreateBitCast(Base, i8PTy),
895                                Idx, "arrayidx");
896    Address = Builder.CreateBitCast(Address, Base->getType());
897  } else {
898    Address = Builder.CreateGEP(Base, Idx, "arrayidx");
899  }
900
901  QualType T = E->getBase()->getType()->getAsPointerType()->getPointeeType();
902  LValue LV = LValue::MakeAddr(Address,
903                               T.getCVRQualifiers(),
904                               getContext().getObjCGCAttrKind(T));
905  if (getContext().getLangOptions().ObjC1 &&
906      getContext().getLangOptions().getGCMode() != LangOptions::NonGC)
907    LValue::SetObjCNonGC(LV, !E->isOBJCGCCandidate(getContext()));
908  return LV;
909}
910
911static
912llvm::Constant *GenerateConstantVector(llvm::SmallVector<unsigned, 4> &Elts) {
913  llvm::SmallVector<llvm::Constant *, 4> CElts;
914
915  for (unsigned i = 0, e = Elts.size(); i != e; ++i)
916    CElts.push_back(llvm::ConstantInt::get(llvm::Type::Int32Ty, Elts[i]));
917
918  return llvm::ConstantVector::get(&CElts[0], CElts.size());
919}
920
921LValue CodeGenFunction::
922EmitExtVectorElementExpr(const ExtVectorElementExpr *E) {
923  // Emit the base vector as an l-value.
924  LValue Base;
925
926  // ExtVectorElementExpr's base can either be a vector or pointer to vector.
927  if (!E->isArrow()) {
928    assert(E->getBase()->getType()->isVectorType());
929    Base = EmitLValue(E->getBase());
930  } else {
931    const PointerType *PT = E->getBase()->getType()->getAsPointerType();
932    llvm::Value *Ptr = EmitScalarExpr(E->getBase());
933    Base = LValue::MakeAddr(Ptr, PT->getPointeeType().getCVRQualifiers());
934  }
935
936  // Encode the element access list into a vector of unsigned indices.
937  llvm::SmallVector<unsigned, 4> Indices;
938  E->getEncodedElementAccess(Indices);
939
940  if (Base.isSimple()) {
941    llvm::Constant *CV = GenerateConstantVector(Indices);
942    return LValue::MakeExtVectorElt(Base.getAddress(), CV,
943                                    Base.getQualifiers());
944  }
945  assert(Base.isExtVectorElt() && "Can only subscript lvalue vec elts here!");
946
947  llvm::Constant *BaseElts = Base.getExtVectorElts();
948  llvm::SmallVector<llvm::Constant *, 4> CElts;
949
950  for (unsigned i = 0, e = Indices.size(); i != e; ++i) {
951    if (isa<llvm::ConstantAggregateZero>(BaseElts))
952      CElts.push_back(llvm::ConstantInt::get(llvm::Type::Int32Ty, 0));
953    else
954      CElts.push_back(BaseElts->getOperand(Indices[i]));
955  }
956  llvm::Constant *CV = llvm::ConstantVector::get(&CElts[0], CElts.size());
957  return LValue::MakeExtVectorElt(Base.getExtVectorAddr(), CV,
958                                  Base.getQualifiers());
959}
960
961LValue CodeGenFunction::EmitMemberExpr(const MemberExpr *E) {
962  bool isUnion = false;
963  bool isIvar = false;
964  bool isNonGC = false;
965  Expr *BaseExpr = E->getBase();
966  llvm::Value *BaseValue = NULL;
967  unsigned CVRQualifiers=0;
968
969  // If this is s.x, emit s as an lvalue.  If it is s->x, emit s as a scalar.
970  if (E->isArrow()) {
971    BaseValue = EmitScalarExpr(BaseExpr);
972    const PointerType *PTy =
973      BaseExpr->getType()->getAsPointerType();
974    if (PTy->getPointeeType()->isUnionType())
975      isUnion = true;
976    CVRQualifiers = PTy->getPointeeType().getCVRQualifiers();
977  } else if (isa<ObjCPropertyRefExpr>(BaseExpr) ||
978             isa<ObjCKVCRefExpr>(BaseExpr)) {
979    RValue RV = EmitObjCPropertyGet(BaseExpr);
980    BaseValue = RV.getAggregateAddr();
981    if (BaseExpr->getType()->isUnionType())
982      isUnion = true;
983    CVRQualifiers = BaseExpr->getType().getCVRQualifiers();
984  } else {
985    LValue BaseLV = EmitLValue(BaseExpr);
986    if (BaseLV.isObjCIvar())
987      isIvar = true;
988    if (BaseLV.isNonGC())
989      isNonGC = true;
990    // FIXME: this isn't right for bitfields.
991    BaseValue = BaseLV.getAddress();
992    if (BaseExpr->getType()->isUnionType())
993      isUnion = true;
994    CVRQualifiers = BaseExpr->getType().getCVRQualifiers();
995  }
996
997  FieldDecl *Field = dyn_cast<FieldDecl>(E->getMemberDecl());
998  // FIXME: Handle non-field member expressions
999  assert(Field && "No code generation for non-field member references");
1000  LValue MemExpLV = EmitLValueForField(BaseValue, Field, isUnion,
1001                                       CVRQualifiers);
1002  LValue::SetObjCIvar(MemExpLV, isIvar);
1003  LValue::SetObjCNonGC(MemExpLV, isNonGC);
1004  return MemExpLV;
1005}
1006
1007LValue CodeGenFunction::EmitLValueForBitfield(llvm::Value* BaseValue,
1008                                              FieldDecl* Field,
1009                                              unsigned CVRQualifiers) {
1010   unsigned idx = CGM.getTypes().getLLVMFieldNo(Field);
1011  // FIXME: CodeGenTypes should expose a method to get the appropriate type for
1012  // FieldTy (the appropriate type is ABI-dependent).
1013  const llvm::Type *FieldTy =
1014    CGM.getTypes().ConvertTypeForMem(Field->getType());
1015  const llvm::PointerType *BaseTy =
1016  cast<llvm::PointerType>(BaseValue->getType());
1017  unsigned AS = BaseTy->getAddressSpace();
1018  BaseValue = Builder.CreateBitCast(BaseValue,
1019                                    llvm::PointerType::get(FieldTy, AS),
1020                                    "tmp");
1021  llvm::Value *V = Builder.CreateGEP(BaseValue,
1022                              llvm::ConstantInt::get(llvm::Type::Int32Ty, idx),
1023                              "tmp");
1024
1025  CodeGenTypes::BitFieldInfo bitFieldInfo =
1026    CGM.getTypes().getBitFieldInfo(Field);
1027  return LValue::MakeBitfield(V, bitFieldInfo.Begin, bitFieldInfo.Size,
1028                              Field->getType()->isSignedIntegerType(),
1029                            Field->getType().getCVRQualifiers()|CVRQualifiers);
1030}
1031
1032LValue CodeGenFunction::EmitLValueForField(llvm::Value* BaseValue,
1033                                           FieldDecl* Field,
1034                                           bool isUnion,
1035                                           unsigned CVRQualifiers)
1036{
1037  if (Field->isBitField())
1038    return EmitLValueForBitfield(BaseValue, Field, CVRQualifiers);
1039
1040  unsigned idx = CGM.getTypes().getLLVMFieldNo(Field);
1041  llvm::Value *V = Builder.CreateStructGEP(BaseValue, idx, "tmp");
1042
1043  // Match union field type.
1044  if (isUnion) {
1045    const llvm::Type *FieldTy =
1046      CGM.getTypes().ConvertTypeForMem(Field->getType());
1047    const llvm::PointerType * BaseTy =
1048      cast<llvm::PointerType>(BaseValue->getType());
1049    unsigned AS = BaseTy->getAddressSpace();
1050    V = Builder.CreateBitCast(V,
1051                              llvm::PointerType::get(FieldTy, AS),
1052                              "tmp");
1053  }
1054  if (Field->getType()->isReferenceType())
1055    V = Builder.CreateLoad(V, "tmp");
1056
1057  QualType::GCAttrTypes attr = QualType::GCNone;
1058  if (CGM.getLangOptions().ObjC1 &&
1059      CGM.getLangOptions().getGCMode() != LangOptions::NonGC) {
1060    QualType Ty = Field->getType();
1061    attr = Ty.getObjCGCAttr();
1062    if (attr != QualType::GCNone) {
1063      // __weak attribute on a field is ignored.
1064      if (attr == QualType::Weak)
1065        attr = QualType::GCNone;
1066    }
1067    else if (getContext().isObjCObjectPointerType(Ty))
1068      attr = QualType::Strong;
1069  }
1070  LValue LV =
1071    LValue::MakeAddr(V,
1072                     Field->getType().getCVRQualifiers()|CVRQualifiers,
1073                     attr);
1074  return LV;
1075}
1076
1077LValue CodeGenFunction::EmitCompoundLiteralLValue(const CompoundLiteralExpr* E){
1078  const llvm::Type *LTy = ConvertType(E->getType());
1079  llvm::Value *DeclPtr = CreateTempAlloca(LTy, ".compoundliteral");
1080
1081  const Expr* InitExpr = E->getInitializer();
1082  LValue Result = LValue::MakeAddr(DeclPtr, E->getType().getCVRQualifiers());
1083
1084  if (E->getType()->isComplexType()) {
1085    EmitComplexExprIntoAddr(InitExpr, DeclPtr, false);
1086  } else if (hasAggregateLLVMType(E->getType())) {
1087    EmitAnyExpr(InitExpr, DeclPtr, false);
1088  } else {
1089    EmitStoreThroughLValue(EmitAnyExpr(InitExpr), Result, E->getType());
1090  }
1091
1092  return Result;
1093}
1094
1095LValue CodeGenFunction::EmitConditionalOperator(const ConditionalOperator* E) {
1096  // We don't handle vectors yet.
1097  if (E->getType()->isVectorType())
1098    return EmitUnsupportedLValue(E, "conditional operator");
1099
1100  // ?: here should be an aggregate.
1101  assert((hasAggregateLLVMType(E->getType()) &&
1102          !E->getType()->isAnyComplexType()) &&
1103         "Unexpected conditional operator!");
1104
1105  llvm::Value *Temp = CreateTempAlloca(ConvertType(E->getType()));
1106  EmitAggExpr(E, Temp, false);
1107
1108  return LValue::MakeAddr(Temp, E->getType().getCVRQualifiers(),
1109                          getContext().getObjCGCAttrKind(E->getType()));
1110
1111}
1112
1113/// EmitCastLValue - Casts are never lvalues.  If a cast is needed by the code
1114/// generator in an lvalue context, then it must mean that we need the address
1115/// of an aggregate in order to access one of its fields.  This can happen for
1116/// all the reasons that casts are permitted with aggregate result, including
1117/// noop aggregate casts, and cast from scalar to union.
1118LValue CodeGenFunction::EmitCastLValue(const CastExpr *E) {
1119  // If this is an aggregate-to-aggregate cast, just use the input's address as
1120  // the lvalue.
1121  if (getContext().hasSameUnqualifiedType(E->getType(),
1122                                          E->getSubExpr()->getType()))
1123    return EmitLValue(E->getSubExpr());
1124
1125  // Otherwise, we must have a cast from scalar to union.
1126  assert(E->getType()->isUnionType() && "Expected scalar-to-union cast");
1127
1128  // Casts are only lvalues when the source and destination types are the same.
1129  llvm::Value *Temp = CreateTempAlloca(ConvertType(E->getType()));
1130  EmitAnyExpr(E->getSubExpr(), Temp, false);
1131
1132  return LValue::MakeAddr(Temp, E->getType().getCVRQualifiers(),
1133                          getContext().getObjCGCAttrKind(E->getType()));
1134}
1135
1136//===--------------------------------------------------------------------===//
1137//                             Expression Emission
1138//===--------------------------------------------------------------------===//
1139
1140
1141RValue CodeGenFunction::EmitCallExpr(const CallExpr *E) {
1142  // Builtins never have block type.
1143  if (E->getCallee()->getType()->isBlockPointerType())
1144    return EmitBlockCallExpr(E);
1145
1146  if (const CXXMemberCallExpr *CE = dyn_cast<CXXMemberCallExpr>(E))
1147    return EmitCXXMemberCallExpr(CE);
1148
1149  const Decl *TargetDecl = 0;
1150  if (const ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(E->getCallee())) {
1151    if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(CE->getSubExpr())) {
1152      TargetDecl = DRE->getDecl();
1153      if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(TargetDecl))
1154        if (unsigned builtinID = FD->getBuiltinID(getContext()))
1155          return EmitBuiltinExpr(FD, builtinID, E);
1156    }
1157  }
1158
1159  if (const CXXOperatorCallExpr *CE = dyn_cast<CXXOperatorCallExpr>(E))
1160    if (const CXXMethodDecl *MD = dyn_cast_or_null<CXXMethodDecl>(TargetDecl))
1161      return EmitCXXOperatorMemberCallExpr(CE, MD);
1162
1163  llvm::Value *Callee = EmitScalarExpr(E->getCallee());
1164  return EmitCall(Callee, E->getCallee()->getType(),
1165                  E->arg_begin(), E->arg_end(), TargetDecl);
1166}
1167
1168LValue CodeGenFunction::EmitBinaryOperatorLValue(const BinaryOperator *E) {
1169  // Comma expressions just emit their LHS then their RHS as an l-value.
1170  if (E->getOpcode() == BinaryOperator::Comma) {
1171    EmitAnyExpr(E->getLHS());
1172    return EmitLValue(E->getRHS());
1173  }
1174
1175  // Can only get l-value for binary operator expressions which are a
1176  // simple assignment of aggregate type.
1177  if (E->getOpcode() != BinaryOperator::Assign)
1178    return EmitUnsupportedLValue(E, "binary l-value expression");
1179
1180  llvm::Value *Temp = CreateTempAlloca(ConvertType(E->getType()));
1181  EmitAggExpr(E, Temp, false);
1182  // FIXME: Are these qualifiers correct?
1183  return LValue::MakeAddr(Temp, E->getType().getCVRQualifiers(),
1184                          getContext().getObjCGCAttrKind(E->getType()));
1185}
1186
1187LValue CodeGenFunction::EmitCallExprLValue(const CallExpr *E) {
1188  RValue RV = EmitCallExpr(E);
1189
1190  if (RV.isScalar()) {
1191    assert(E->getCallReturnType()->isReferenceType() &&
1192           "Can't have a scalar return unless the return type is a "
1193           "reference type!");
1194
1195    return LValue::MakeAddr(RV.getScalarVal(), E->getType().getCVRQualifiers(),
1196                            getContext().getObjCGCAttrKind(E->getType()));
1197  }
1198
1199  return LValue::MakeAddr(RV.getAggregateAddr(),
1200                          E->getType().getCVRQualifiers(),
1201                          getContext().getObjCGCAttrKind(E->getType()));
1202}
1203
1204LValue CodeGenFunction::EmitVAArgExprLValue(const VAArgExpr *E) {
1205  // FIXME: This shouldn't require another copy.
1206  llvm::Value *Temp = CreateTempAlloca(ConvertType(E->getType()));
1207  EmitAggExpr(E, Temp, false);
1208  return LValue::MakeAddr(Temp, E->getType().getCVRQualifiers());
1209}
1210
1211LValue
1212CodeGenFunction::EmitCXXConditionDeclLValue(const CXXConditionDeclExpr *E) {
1213  EmitLocalBlockVarDecl(*E->getVarDecl());
1214  return EmitDeclRefLValue(E);
1215}
1216
1217LValue CodeGenFunction::EmitCXXConstructLValue(const CXXConstructExpr *E) {
1218  llvm::Value *Temp = CreateTempAlloca(ConvertTypeForMem(E->getType()), "tmp");
1219  EmitCXXConstructExpr(Temp, E);
1220  return LValue::MakeAddr(Temp, E->getType().getCVRQualifiers());
1221}
1222
1223LValue
1224CodeGenFunction::EmitCXXBindTemporaryLValue(const CXXBindTemporaryExpr *E) {
1225  LValue LV = EmitLValue(E->getSubExpr());
1226
1227  PushCXXTemporary(E->getTemporary(), LV.getAddress());
1228
1229  return LV;
1230}
1231
1232LValue CodeGenFunction::EmitObjCMessageExprLValue(const ObjCMessageExpr *E) {
1233  // Can only get l-value for message expression returning aggregate type
1234  RValue RV = EmitObjCMessageExpr(E);
1235  // FIXME: can this be volatile?
1236  return LValue::MakeAddr(RV.getAggregateAddr(),
1237                          E->getType().getCVRQualifiers(),
1238                          getContext().getObjCGCAttrKind(E->getType()));
1239}
1240
1241llvm::Value *CodeGenFunction::EmitIvarOffset(const ObjCInterfaceDecl *Interface,
1242                                             const ObjCIvarDecl *Ivar) {
1243  return CGM.getObjCRuntime().EmitIvarOffset(*this, Interface, Ivar);
1244}
1245
1246LValue CodeGenFunction::EmitLValueForIvar(QualType ObjectTy,
1247                                          llvm::Value *BaseValue,
1248                                          const ObjCIvarDecl *Ivar,
1249                                          unsigned CVRQualifiers) {
1250  return CGM.getObjCRuntime().EmitObjCValueForIvar(*this, ObjectTy, BaseValue,
1251                                                   Ivar, CVRQualifiers);
1252}
1253
1254LValue CodeGenFunction::EmitObjCIvarRefLValue(const ObjCIvarRefExpr *E) {
1255  // FIXME: A lot of the code below could be shared with EmitMemberExpr.
1256  llvm::Value *BaseValue = 0;
1257  const Expr *BaseExpr = E->getBase();
1258  unsigned CVRQualifiers = 0;
1259  QualType ObjectTy;
1260  if (E->isArrow()) {
1261    BaseValue = EmitScalarExpr(BaseExpr);
1262    const PointerType *PTy = BaseExpr->getType()->getAsPointerType();
1263    ObjectTy = PTy->getPointeeType();
1264    CVRQualifiers = ObjectTy.getCVRQualifiers();
1265  } else {
1266    LValue BaseLV = EmitLValue(BaseExpr);
1267    // FIXME: this isn't right for bitfields.
1268    BaseValue = BaseLV.getAddress();
1269    ObjectTy = BaseExpr->getType();
1270    CVRQualifiers = ObjectTy.getCVRQualifiers();
1271  }
1272
1273  return EmitLValueForIvar(ObjectTy, BaseValue, E->getDecl(), CVRQualifiers);
1274}
1275
1276LValue
1277CodeGenFunction::EmitObjCPropertyRefLValue(const ObjCPropertyRefExpr *E) {
1278  // This is a special l-value that just issues sends when we load or
1279  // store through it.
1280  return LValue::MakePropertyRef(E, E->getType().getCVRQualifiers());
1281}
1282
1283LValue
1284CodeGenFunction::EmitObjCKVCRefLValue(const ObjCKVCRefExpr *E) {
1285  // This is a special l-value that just issues sends when we load or
1286  // store through it.
1287  return LValue::MakeKVCRef(E, E->getType().getCVRQualifiers());
1288}
1289
1290LValue
1291CodeGenFunction::EmitObjCSuperExprLValue(const ObjCSuperExpr *E) {
1292  return EmitUnsupportedLValue(E, "use of super");
1293}
1294
1295LValue CodeGenFunction::EmitStmtExprLValue(const StmtExpr *E) {
1296
1297  // Can only get l-value for message expression returning aggregate type
1298  RValue RV = EmitAnyExprToTemp(E);
1299  // FIXME: can this be volatile?
1300  return LValue::MakeAddr(RV.getAggregateAddr(),
1301                          E->getType().getCVRQualifiers(),
1302                          getContext().getObjCGCAttrKind(E->getType()));
1303}
1304
1305
1306RValue CodeGenFunction::EmitCall(llvm::Value *Callee, QualType CalleeType,
1307                                 CallExpr::const_arg_iterator ArgBeg,
1308                                 CallExpr::const_arg_iterator ArgEnd,
1309                                 const Decl *TargetDecl) {
1310  // Get the actual function type. The callee type will always be a
1311  // pointer to function type or a block pointer type.
1312  assert(CalleeType->isFunctionPointerType() &&
1313         "Call must have function pointer type!");
1314
1315  QualType FnType = CalleeType->getAsPointerType()->getPointeeType();
1316  QualType ResultType = FnType->getAsFunctionType()->getResultType();
1317
1318  CallArgList Args;
1319  EmitCallArgs(Args, FnType->getAsFunctionProtoType(), ArgBeg, ArgEnd);
1320
1321  return EmitCall(CGM.getTypes().getFunctionInfo(ResultType, Args),
1322                  Callee, Args, TargetDecl);
1323}
1324