CGExpr.cpp revision 14108da7f7fc059772711e4ffee1322a27b152a7 
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  Builder.CreateStore(Value, Addr, Volatile);
261}
262
263/// EmitLoadOfLValue - Given an expression that represents a value lvalue,
264/// this method emits the address of the lvalue, then loads the result as an
265/// rvalue, returning the rvalue.
266RValue CodeGenFunction::EmitLoadOfLValue(LValue LV, QualType ExprType) {
267  if (LV.isObjCWeak()) {
268    // load of a __weak object.
269    llvm::Value *AddrWeakObj = LV.getAddress();
270    llvm::Value *read_weak = CGM.getObjCRuntime().EmitObjCWeakRead(*this,
271                                                                   AddrWeakObj);
272    return RValue::get(read_weak);
273  }
274
275  if (LV.isSimple()) {
276    llvm::Value *Ptr = LV.getAddress();
277    const llvm::Type *EltTy =
278      cast<llvm::PointerType>(Ptr->getType())->getElementType();
279
280    // Simple scalar l-value.
281    if (EltTy->isSingleValueType())
282      return RValue::get(EmitLoadOfScalar(Ptr, LV.isVolatileQualified(),
283                                          ExprType));
284
285    assert(ExprType->isFunctionType() && "Unknown scalar value");
286    return RValue::get(Ptr);
287  }
288
289  if (LV.isVectorElt()) {
290    llvm::Value *Vec = Builder.CreateLoad(LV.getVectorAddr(),
291                                          LV.isVolatileQualified(), "tmp");
292    return RValue::get(Builder.CreateExtractElement(Vec, LV.getVectorIdx(),
293                                                    "vecext"));
294  }
295
296  // If this is a reference to a subset of the elements of a vector, either
297  // shuffle the input or extract/insert them as appropriate.
298  if (LV.isExtVectorElt())
299    return EmitLoadOfExtVectorElementLValue(LV, ExprType);
300
301  if (LV.isBitfield())
302    return EmitLoadOfBitfieldLValue(LV, ExprType);
303
304  if (LV.isPropertyRef())
305    return EmitLoadOfPropertyRefLValue(LV, ExprType);
306
307  assert(LV.isKVCRef() && "Unknown LValue type!");
308  return EmitLoadOfKVCRefLValue(LV, ExprType);
309}
310
311RValue CodeGenFunction::EmitLoadOfBitfieldLValue(LValue LV,
312                                                 QualType ExprType) {
313  unsigned StartBit = LV.getBitfieldStartBit();
314  unsigned BitfieldSize = LV.getBitfieldSize();
315  llvm::Value *Ptr = LV.getBitfieldAddr();
316
317  const llvm::Type *EltTy =
318    cast<llvm::PointerType>(Ptr->getType())->getElementType();
319  unsigned EltTySize = CGM.getTargetData().getTypeSizeInBits(EltTy);
320
321  // In some cases the bitfield may straddle two memory locations.
322  // Currently we load the entire bitfield, then do the magic to
323  // sign-extend it if necessary. This results in somewhat more code
324  // than necessary for the common case (one load), since two shifts
325  // accomplish both the masking and sign extension.
326  unsigned LowBits = std::min(BitfieldSize, EltTySize - StartBit);
327  llvm::Value *Val = Builder.CreateLoad(Ptr, LV.isVolatileQualified(), "tmp");
328
329  // Shift to proper location.
330  if (StartBit)
331    Val = Builder.CreateLShr(Val, llvm::ConstantInt::get(EltTy, StartBit),
332                             "bf.lo");
333
334  // Mask off unused bits.
335  llvm::Constant *LowMask =
336    llvm::ConstantInt::get(llvm::APInt::getLowBitsSet(EltTySize, LowBits));
337  Val = Builder.CreateAnd(Val, LowMask, "bf.lo.cleared");
338
339  // Fetch the high bits if necessary.
340  if (LowBits < BitfieldSize) {
341    unsigned HighBits = BitfieldSize - LowBits;
342    llvm::Value *HighPtr =
343      Builder.CreateGEP(Ptr, llvm::ConstantInt::get(llvm::Type::Int32Ty, 1),
344                        "bf.ptr.hi");
345    llvm::Value *HighVal = Builder.CreateLoad(HighPtr,
346                                              LV.isVolatileQualified(),
347                                              "tmp");
348
349    // Mask off unused bits.
350    llvm::Constant *HighMask =
351      llvm::ConstantInt::get(llvm::APInt::getLowBitsSet(EltTySize, HighBits));
352    HighVal = Builder.CreateAnd(HighVal, HighMask, "bf.lo.cleared");
353
354    // Shift to proper location and or in to bitfield value.
355    HighVal = Builder.CreateShl(HighVal,
356                                llvm::ConstantInt::get(EltTy, LowBits));
357    Val = Builder.CreateOr(Val, HighVal, "bf.val");
358  }
359
360  // Sign extend if necessary.
361  if (LV.isBitfieldSigned()) {
362    llvm::Value *ExtraBits = llvm::ConstantInt::get(EltTy,
363                                                    EltTySize - BitfieldSize);
364    Val = Builder.CreateAShr(Builder.CreateShl(Val, ExtraBits),
365                             ExtraBits, "bf.val.sext");
366  }
367
368  // The bitfield type and the normal type differ when the storage sizes
369  // differ (currently just _Bool).
370  Val = Builder.CreateIntCast(Val, ConvertType(ExprType), false, "tmp");
371
372  return RValue::get(Val);
373}
374
375RValue CodeGenFunction::EmitLoadOfPropertyRefLValue(LValue LV,
376                                                    QualType ExprType) {
377  return EmitObjCPropertyGet(LV.getPropertyRefExpr());
378}
379
380RValue CodeGenFunction::EmitLoadOfKVCRefLValue(LValue LV,
381                                               QualType ExprType) {
382  return EmitObjCPropertyGet(LV.getKVCRefExpr());
383}
384
385// If this is a reference to a subset of the elements of a vector, create an
386// appropriate shufflevector.
387RValue CodeGenFunction::EmitLoadOfExtVectorElementLValue(LValue LV,
388                                                         QualType ExprType) {
389  llvm::Value *Vec = Builder.CreateLoad(LV.getExtVectorAddr(),
390                                        LV.isVolatileQualified(), "tmp");
391
392  const llvm::Constant *Elts = LV.getExtVectorElts();
393
394  // If the result of the expression is a non-vector type, we must be
395  // extracting a single element.  Just codegen as an extractelement.
396  const VectorType *ExprVT = ExprType->getAsVectorType();
397  if (!ExprVT) {
398    unsigned InIdx = getAccessedFieldNo(0, Elts);
399    llvm::Value *Elt = llvm::ConstantInt::get(llvm::Type::Int32Ty, InIdx);
400    return RValue::get(Builder.CreateExtractElement(Vec, Elt, "tmp"));
401  }
402
403  // Always use shuffle vector to try to retain the original program structure
404  unsigned NumResultElts = ExprVT->getNumElements();
405
406  llvm::SmallVector<llvm::Constant*, 4> Mask;
407  for (unsigned i = 0; i != NumResultElts; ++i) {
408    unsigned InIdx = getAccessedFieldNo(i, Elts);
409    Mask.push_back(llvm::ConstantInt::get(llvm::Type::Int32Ty, InIdx));
410  }
411
412  llvm::Value *MaskV = llvm::ConstantVector::get(&Mask[0], Mask.size());
413  Vec = Builder.CreateShuffleVector(Vec,
414                                    llvm::UndefValue::get(Vec->getType()),
415                                    MaskV, "tmp");
416  return RValue::get(Vec);
417}
418
419
420
421/// EmitStoreThroughLValue - Store the specified rvalue into the specified
422/// lvalue, where both are guaranteed to the have the same type, and that type
423/// is 'Ty'.
424void CodeGenFunction::EmitStoreThroughLValue(RValue Src, LValue Dst,
425                                             QualType Ty) {
426  if (!Dst.isSimple()) {
427    if (Dst.isVectorElt()) {
428      // Read/modify/write the vector, inserting the new element.
429      llvm::Value *Vec = Builder.CreateLoad(Dst.getVectorAddr(),
430                                            Dst.isVolatileQualified(), "tmp");
431      Vec = Builder.CreateInsertElement(Vec, Src.getScalarVal(),
432                                        Dst.getVectorIdx(), "vecins");
433      Builder.CreateStore(Vec, Dst.getVectorAddr(),Dst.isVolatileQualified());
434      return;
435    }
436
437    // If this is an update of extended vector elements, insert them as
438    // appropriate.
439    if (Dst.isExtVectorElt())
440      return EmitStoreThroughExtVectorComponentLValue(Src, Dst, Ty);
441
442    if (Dst.isBitfield())
443      return EmitStoreThroughBitfieldLValue(Src, Dst, Ty);
444
445    if (Dst.isPropertyRef())
446      return EmitStoreThroughPropertyRefLValue(Src, Dst, Ty);
447
448    if (Dst.isKVCRef())
449      return EmitStoreThroughKVCRefLValue(Src, Dst, Ty);
450
451    assert(0 && "Unknown LValue type");
452  }
453
454  if (Dst.isObjCWeak() && !Dst.isNonGC()) {
455    // load of a __weak object.
456    llvm::Value *LvalueDst = Dst.getAddress();
457    llvm::Value *src = Src.getScalarVal();
458     CGM.getObjCRuntime().EmitObjCWeakAssign(*this, src, LvalueDst);
459    return;
460  }
461
462  if (Dst.isObjCStrong() && !Dst.isNonGC()) {
463    // load of a __strong object.
464    llvm::Value *LvalueDst = Dst.getAddress();
465    llvm::Value *src = Src.getScalarVal();
466#if 0
467    // FIXME. We cannot positively determine if we have an 'ivar' assignment,
468    // object assignment or an unknown assignment. For now, generate call to
469    // objc_assign_strongCast assignment which is a safe, but consevative
470    // assumption.
471    if (Dst.isObjCIvar())
472      CGM.getObjCRuntime().EmitObjCIvarAssign(*this, src, LvalueDst);
473    else
474      CGM.getObjCRuntime().EmitObjCGlobalAssign(*this, src, LvalueDst);
475#endif
476    if (Dst.isGlobalObjCRef())
477      CGM.getObjCRuntime().EmitObjCGlobalAssign(*this, src, LvalueDst);
478    else
479      CGM.getObjCRuntime().EmitObjCStrongCastAssign(*this, src, LvalueDst);
480    return;
481  }
482
483  assert(Src.isScalar() && "Can't emit an agg store with this method");
484  EmitStoreOfScalar(Src.getScalarVal(), Dst.getAddress(),
485                    Dst.isVolatileQualified(), Ty);
486}
487
488void CodeGenFunction::EmitStoreThroughBitfieldLValue(RValue Src, LValue Dst,
489                                                     QualType Ty,
490                                                     llvm::Value **Result) {
491  unsigned StartBit = Dst.getBitfieldStartBit();
492  unsigned BitfieldSize = Dst.getBitfieldSize();
493  llvm::Value *Ptr = Dst.getBitfieldAddr();
494
495  const llvm::Type *EltTy =
496    cast<llvm::PointerType>(Ptr->getType())->getElementType();
497  unsigned EltTySize = CGM.getTargetData().getTypeSizeInBits(EltTy);
498
499  // Get the new value, cast to the appropriate type and masked to
500  // exactly the size of the bit-field.
501  llvm::Value *SrcVal = Src.getScalarVal();
502  llvm::Value *NewVal = Builder.CreateIntCast(SrcVal, EltTy, false, "tmp");
503  llvm::Constant *Mask =
504    llvm::ConstantInt::get(llvm::APInt::getLowBitsSet(EltTySize, BitfieldSize));
505  NewVal = Builder.CreateAnd(NewVal, Mask, "bf.value");
506
507  // Return the new value of the bit-field, if requested.
508  if (Result) {
509    // Cast back to the proper type for result.
510    const llvm::Type *SrcTy = SrcVal->getType();
511    llvm::Value *SrcTrunc = Builder.CreateIntCast(NewVal, SrcTy, false,
512                                                  "bf.reload.val");
513
514    // Sign extend if necessary.
515    if (Dst.isBitfieldSigned()) {
516      unsigned SrcTySize = CGM.getTargetData().getTypeSizeInBits(SrcTy);
517      llvm::Value *ExtraBits = llvm::ConstantInt::get(SrcTy,
518                                                      SrcTySize - BitfieldSize);
519      SrcTrunc = Builder.CreateAShr(Builder.CreateShl(SrcTrunc, ExtraBits),
520                                    ExtraBits, "bf.reload.sext");
521    }
522
523    *Result = SrcTrunc;
524  }
525
526  // In some cases the bitfield may straddle two memory locations.
527  // Emit the low part first and check to see if the high needs to be
528  // done.
529  unsigned LowBits = std::min(BitfieldSize, EltTySize - StartBit);
530  llvm::Value *LowVal = Builder.CreateLoad(Ptr, Dst.isVolatileQualified(),
531                                           "bf.prev.low");
532
533  // Compute the mask for zero-ing the low part of this bitfield.
534  llvm::Constant *InvMask =
535    llvm::ConstantInt::get(~llvm::APInt::getBitsSet(EltTySize, StartBit,
536                                                    StartBit + LowBits));
537
538  // Compute the new low part as
539  //   LowVal = (LowVal & InvMask) | (NewVal << StartBit),
540  // with the shift of NewVal implicitly stripping the high bits.
541  llvm::Value *NewLowVal =
542    Builder.CreateShl(NewVal, llvm::ConstantInt::get(EltTy, StartBit),
543                      "bf.value.lo");
544  LowVal = Builder.CreateAnd(LowVal, InvMask, "bf.prev.lo.cleared");
545  LowVal = Builder.CreateOr(LowVal, NewLowVal, "bf.new.lo");
546
547  // Write back.
548  Builder.CreateStore(LowVal, Ptr, Dst.isVolatileQualified());
549
550  // If the low part doesn't cover the bitfield emit a high part.
551  if (LowBits < BitfieldSize) {
552    unsigned HighBits = BitfieldSize - LowBits;
553    llvm::Value *HighPtr =
554      Builder.CreateGEP(Ptr, llvm::ConstantInt::get(llvm::Type::Int32Ty, 1),
555                        "bf.ptr.hi");
556    llvm::Value *HighVal = Builder.CreateLoad(HighPtr,
557                                              Dst.isVolatileQualified(),
558                                              "bf.prev.hi");
559
560    // Compute the mask for zero-ing the high part of this bitfield.
561    llvm::Constant *InvMask =
562      llvm::ConstantInt::get(~llvm::APInt::getLowBitsSet(EltTySize, HighBits));
563
564    // Compute the new high part as
565    //   HighVal = (HighVal & InvMask) | (NewVal lshr LowBits),
566    // where the high bits of NewVal have already been cleared and the
567    // shift stripping the low bits.
568    llvm::Value *NewHighVal =
569      Builder.CreateLShr(NewVal, llvm::ConstantInt::get(EltTy, LowBits),
570                        "bf.value.high");
571    HighVal = Builder.CreateAnd(HighVal, InvMask, "bf.prev.hi.cleared");
572    HighVal = Builder.CreateOr(HighVal, NewHighVal, "bf.new.hi");
573
574    // Write back.
575    Builder.CreateStore(HighVal, HighPtr, Dst.isVolatileQualified());
576  }
577}
578
579void CodeGenFunction::EmitStoreThroughPropertyRefLValue(RValue Src,
580                                                        LValue Dst,
581                                                        QualType Ty) {
582  EmitObjCPropertySet(Dst.getPropertyRefExpr(), Src);
583}
584
585void CodeGenFunction::EmitStoreThroughKVCRefLValue(RValue Src,
586                                                   LValue Dst,
587                                                   QualType Ty) {
588  EmitObjCPropertySet(Dst.getKVCRefExpr(), Src);
589}
590
591void CodeGenFunction::EmitStoreThroughExtVectorComponentLValue(RValue Src,
592                                                               LValue Dst,
593                                                               QualType Ty) {
594  // This access turns into a read/modify/write of the vector.  Load the input
595  // value now.
596  llvm::Value *Vec = Builder.CreateLoad(Dst.getExtVectorAddr(),
597                                        Dst.isVolatileQualified(), "tmp");
598  const llvm::Constant *Elts = Dst.getExtVectorElts();
599
600  llvm::Value *SrcVal = Src.getScalarVal();
601
602  if (const VectorType *VTy = Ty->getAsVectorType()) {
603    unsigned NumSrcElts = VTy->getNumElements();
604    unsigned NumDstElts =
605       cast<llvm::VectorType>(Vec->getType())->getNumElements();
606    if (NumDstElts == NumSrcElts) {
607      // Use shuffle vector is the src and destination are the same number
608      // of elements and restore the vector mask since it is on the side
609      // it will be stored.
610      llvm::SmallVector<llvm::Constant*, 4> Mask(NumDstElts);
611      for (unsigned i = 0; i != NumSrcElts; ++i) {
612        unsigned InIdx = getAccessedFieldNo(i, Elts);
613        Mask[InIdx] = llvm::ConstantInt::get(llvm::Type::Int32Ty, i);
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() &&
672      !VD->hasAttr<BlocksAttr>();
673    if (VD->hasExternalStorage()) {
674      llvm::Value *V = CGM.GetAddrOfGlobalVar(VD);
675      if (VD->getType()->isReferenceType())
676        V = Builder.CreateLoad(V, "tmp");
677      LV = LValue::MakeAddr(V, E->getType().getCVRQualifiers(),
678                            getContext().getObjCGCAttrKind(E->getType()));
679    }
680    else {
681      llvm::Value *V = LocalDeclMap[VD];
682      assert(V && "DeclRefExpr not entered in LocalDeclMap?");
683      // local variables do not get their gc attribute set.
684      QualType::GCAttrTypes attr = QualType::GCNone;
685      // local static?
686      if (!NonGCable)
687        attr = getContext().getObjCGCAttrKind(E->getType());
688      if (VD->hasAttr<BlocksAttr>()) {
689        bool needsCopyDispose = BlockRequiresCopying(VD->getType());
690        const llvm::Type *PtrStructTy = V->getType();
691        const llvm::Type *Ty = PtrStructTy;
692        Ty = llvm::PointerType::get(Ty, 0);
693        V = Builder.CreateStructGEP(V, 1, "forwarding");
694        V = Builder.CreateBitCast(V, Ty);
695        V = Builder.CreateLoad(V, false);
696        V = Builder.CreateBitCast(V, PtrStructTy);
697        V = Builder.CreateStructGEP(V, needsCopyDispose*2 + 4, "x");
698      }
699      if (VD->getType()->isReferenceType())
700        V = Builder.CreateLoad(V, "tmp");
701      LV = LValue::MakeAddr(V, E->getType().getCVRQualifiers(), attr);
702    }
703    LValue::SetObjCNonGC(LV, NonGCable);
704    return LV;
705  } else if (VD && VD->isFileVarDecl()) {
706    llvm::Value *V = CGM.GetAddrOfGlobalVar(VD);
707    if (VD->getType()->isReferenceType())
708      V = Builder.CreateLoad(V, "tmp");
709    LValue LV = LValue::MakeAddr(V, E->getType().getCVRQualifiers(),
710                                 getContext().getObjCGCAttrKind(E->getType()));
711    if (LV.isObjCStrong())
712      LV.SetGlobalObjCRef(LV, true);
713    return LV;
714  } else if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(E->getDecl())) {
715    llvm::Value* V = CGM.GetAddrOfFunction(GlobalDecl(FD));
716    if (!FD->hasPrototype()) {
717      if (const FunctionProtoType *Proto =
718              FD->getType()->getAsFunctionProtoType()) {
719        // Ugly case: for a K&R-style definition, the type of the definition
720        // isn't the same as the type of a use.  Correct for this with a
721        // bitcast.
722        QualType NoProtoType =
723            getContext().getFunctionNoProtoType(Proto->getResultType());
724        NoProtoType = getContext().getPointerType(NoProtoType);
725        V = Builder.CreateBitCast(V, ConvertType(NoProtoType), "tmp");
726      }
727    }
728    return LValue::MakeAddr(V, E->getType().getCVRQualifiers(),
729                            getContext().getObjCGCAttrKind(E->getType()));
730  }
731  else if (const ImplicitParamDecl *IPD =
732      dyn_cast<ImplicitParamDecl>(E->getDecl())) {
733    llvm::Value *V = LocalDeclMap[IPD];
734    assert(V && "BlockVarDecl not entered in LocalDeclMap?");
735    return LValue::MakeAddr(V, E->getType().getCVRQualifiers(),
736                            getContext().getObjCGCAttrKind(E->getType()));
737  }
738  assert(0 && "Unimp declref");
739  //an invalid LValue, but the assert will
740  //ensure that this point is never reached.
741  return LValue();
742}
743
744LValue CodeGenFunction::EmitBlockDeclRefLValue(const BlockDeclRefExpr *E) {
745  return LValue::MakeAddr(GetAddrOfBlockDecl(E),
746                          E->getType().getCVRQualifiers(),
747                          getContext().getObjCGCAttrKind(E->getType()));
748}
749
750LValue CodeGenFunction::EmitUnaryOpLValue(const UnaryOperator *E) {
751  // __extension__ doesn't affect lvalue-ness.
752  if (E->getOpcode() == UnaryOperator::Extension)
753    return EmitLValue(E->getSubExpr());
754
755  QualType ExprTy = getContext().getCanonicalType(E->getSubExpr()->getType());
756  switch (E->getOpcode()) {
757  default: assert(0 && "Unknown unary operator lvalue!");
758  case UnaryOperator::Deref:
759    {
760      QualType T = E->getSubExpr()->getType()->getPointeeType();
761      assert(!T.isNull() && "CodeGenFunction::EmitUnaryOpLValue: Illegal type");
762
763      LValue LV = LValue::MakeAddr(EmitScalarExpr(E->getSubExpr()),
764                                   T.getCVRQualifiers(),
765                                   getContext().getObjCGCAttrKind(T));
766     // We should not generate __weak write barrier on indirect reference
767     // of a pointer to object; as in void foo (__weak id *param); *param = 0;
768     // But, we continue to generate __strong write barrier on indirect write
769     // into a pointer to object.
770     if (getContext().getLangOptions().ObjC1 &&
771         getContext().getLangOptions().getGCMode() != LangOptions::NonGC &&
772         LV.isObjCWeak())
773       LValue::SetObjCNonGC(LV, !E->isOBJCGCCandidate(getContext()));
774     return LV;
775    }
776  case UnaryOperator::Real:
777  case UnaryOperator::Imag:
778    LValue LV = EmitLValue(E->getSubExpr());
779    unsigned Idx = E->getOpcode() == UnaryOperator::Imag;
780    return LValue::MakeAddr(Builder.CreateStructGEP(LV.getAddress(),
781                                                    Idx, "idx"),
782                            ExprTy.getCVRQualifiers());
783  }
784}
785
786LValue CodeGenFunction::EmitStringLiteralLValue(const StringLiteral *E) {
787  return LValue::MakeAddr(CGM.GetAddrOfConstantStringFromLiteral(E), 0);
788}
789
790LValue CodeGenFunction::EmitObjCEncodeExprLValue(const ObjCEncodeExpr *E) {
791  return LValue::MakeAddr(CGM.GetAddrOfConstantStringFromObjCEncode(E), 0);
792}
793
794
795LValue CodeGenFunction::EmitPredefinedFunctionName(unsigned Type) {
796  std::string GlobalVarName;
797
798  switch (Type) {
799  default:
800    assert(0 && "Invalid type");
801  case PredefinedExpr::Func:
802    GlobalVarName = "__func__.";
803    break;
804  case PredefinedExpr::Function:
805    GlobalVarName = "__FUNCTION__.";
806    break;
807  case PredefinedExpr::PrettyFunction:
808    // FIXME:: Demangle C++ method names
809    GlobalVarName = "__PRETTY_FUNCTION__.";
810    break;
811  }
812
813  // FIXME: This isn't right at all.  The logic for computing this should go
814  // into a method on PredefinedExpr.  This would allow sema and codegen to be
815  // consistent for things like sizeof(__func__) etc.
816  std::string FunctionName;
817  if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(CurCodeDecl)) {
818    FunctionName = CGM.getMangledName(FD);
819  } else {
820    // Just get the mangled name; skipping the asm prefix if it
821    // exists.
822    FunctionName = CurFn->getName();
823    if (FunctionName[0] == '\01')
824      FunctionName = FunctionName.substr(1, std::string::npos);
825  }
826
827  GlobalVarName += FunctionName;
828  llvm::Constant *C =
829    CGM.GetAddrOfConstantCString(FunctionName, GlobalVarName.c_str());
830  return LValue::MakeAddr(C, 0);
831}
832
833LValue CodeGenFunction::EmitPredefinedLValue(const PredefinedExpr *E) {
834  switch (E->getIdentType()) {
835  default:
836    return EmitUnsupportedLValue(E, "predefined expression");
837  case PredefinedExpr::Func:
838  case PredefinedExpr::Function:
839  case PredefinedExpr::PrettyFunction:
840    return EmitPredefinedFunctionName(E->getIdentType());
841  }
842}
843
844LValue CodeGenFunction::EmitArraySubscriptExpr(const ArraySubscriptExpr *E) {
845  // The index must always be an integer, which is not an aggregate.  Emit it.
846  llvm::Value *Idx = EmitScalarExpr(E->getIdx());
847  QualType IdxTy  = E->getIdx()->getType();
848  bool IdxSigned = IdxTy->isSignedIntegerType();
849
850  // If the base is a vector type, then we are forming a vector element lvalue
851  // with this subscript.
852  if (E->getBase()->getType()->isVectorType()) {
853    // Emit the vector as an lvalue to get its address.
854    LValue LHS = EmitLValue(E->getBase());
855    assert(LHS.isSimple() && "Can only subscript lvalue vectors here!");
856    Idx = Builder.CreateIntCast(Idx, llvm::Type::Int32Ty, IdxSigned, "vidx");
857    return LValue::MakeVectorElt(LHS.getAddress(), Idx,
858      E->getBase()->getType().getCVRQualifiers());
859  }
860
861  // The base must be a pointer, which is not an aggregate.  Emit it.
862  llvm::Value *Base = EmitScalarExpr(E->getBase());
863
864  // Extend or truncate the index type to 32 or 64-bits.
865  unsigned IdxBitwidth = cast<llvm::IntegerType>(Idx->getType())->getBitWidth();
866  if (IdxBitwidth != LLVMPointerWidth)
867    Idx = Builder.CreateIntCast(Idx, llvm::IntegerType::get(LLVMPointerWidth),
868                                IdxSigned, "idxprom");
869
870  // We know that the pointer points to a type of the correct size,
871  // unless the size is a VLA or Objective-C interface.
872  llvm::Value *Address = 0;
873  if (const VariableArrayType *VAT =
874        getContext().getAsVariableArrayType(E->getType())) {
875    llvm::Value *VLASize = VLASizeMap[VAT];
876
877    Idx = Builder.CreateMul(Idx, VLASize);
878
879    QualType BaseType = getContext().getBaseElementType(VAT);
880
881    uint64_t BaseTypeSize = getContext().getTypeSize(BaseType) / 8;
882    Idx = Builder.CreateUDiv(Idx,
883                             llvm::ConstantInt::get(Idx->getType(),
884                                                    BaseTypeSize));
885    Address = Builder.CreateGEP(Base, Idx, "arrayidx");
886  } else if (const ObjCInterfaceType *OIT =
887             dyn_cast<ObjCInterfaceType>(E->getType())) {
888    llvm::Value *InterfaceSize =
889      llvm::ConstantInt::get(Idx->getType(),
890                             getContext().getTypeSize(OIT) / 8);
891
892    Idx = Builder.CreateMul(Idx, InterfaceSize);
893
894    llvm::Type *i8PTy = llvm::PointerType::getUnqual(llvm::Type::Int8Ty);
895    Address = Builder.CreateGEP(Builder.CreateBitCast(Base, i8PTy),
896                                Idx, "arrayidx");
897    Address = Builder.CreateBitCast(Address, Base->getType());
898  } else {
899    Address = Builder.CreateGEP(Base, Idx, "arrayidx");
900  }
901
902  QualType T = E->getBase()->getType()->getPointeeType();
903  assert(!T.isNull() &&
904         "CodeGenFunction::EmitArraySubscriptExpr(): Illegal base type");
905
906  LValue LV = LValue::MakeAddr(Address,
907                               T.getCVRQualifiers(),
908                               getContext().getObjCGCAttrKind(T));
909  if (getContext().getLangOptions().ObjC1 &&
910      getContext().getLangOptions().getGCMode() != LangOptions::NonGC)
911    LValue::SetObjCNonGC(LV, !E->isOBJCGCCandidate(getContext()));
912  return LV;
913}
914
915static
916llvm::Constant *GenerateConstantVector(llvm::SmallVector<unsigned, 4> &Elts) {
917  llvm::SmallVector<llvm::Constant *, 4> CElts;
918
919  for (unsigned i = 0, e = Elts.size(); i != e; ++i)
920    CElts.push_back(llvm::ConstantInt::get(llvm::Type::Int32Ty, Elts[i]));
921
922  return llvm::ConstantVector::get(&CElts[0], CElts.size());
923}
924
925LValue CodeGenFunction::
926EmitExtVectorElementExpr(const ExtVectorElementExpr *E) {
927  // Emit the base vector as an l-value.
928  LValue Base;
929
930  // ExtVectorElementExpr's base can either be a vector or pointer to vector.
931  if (!E->isArrow()) {
932    assert(E->getBase()->getType()->isVectorType());
933    Base = EmitLValue(E->getBase());
934  } else {
935    const PointerType *PT = E->getBase()->getType()->getAsPointerType();
936    llvm::Value *Ptr = EmitScalarExpr(E->getBase());
937    Base = LValue::MakeAddr(Ptr, PT->getPointeeType().getCVRQualifiers());
938  }
939
940  // Encode the element access list into a vector of unsigned indices.
941  llvm::SmallVector<unsigned, 4> Indices;
942  E->getEncodedElementAccess(Indices);
943
944  if (Base.isSimple()) {
945    llvm::Constant *CV = GenerateConstantVector(Indices);
946    return LValue::MakeExtVectorElt(Base.getAddress(), CV,
947                                    Base.getQualifiers());
948  }
949  assert(Base.isExtVectorElt() && "Can only subscript lvalue vec elts here!");
950
951  llvm::Constant *BaseElts = Base.getExtVectorElts();
952  llvm::SmallVector<llvm::Constant *, 4> CElts;
953
954  for (unsigned i = 0, e = Indices.size(); i != e; ++i) {
955    if (isa<llvm::ConstantAggregateZero>(BaseElts))
956      CElts.push_back(llvm::ConstantInt::get(llvm::Type::Int32Ty, 0));
957    else
958      CElts.push_back(BaseElts->getOperand(Indices[i]));
959  }
960  llvm::Constant *CV = llvm::ConstantVector::get(&CElts[0], CElts.size());
961  return LValue::MakeExtVectorElt(Base.getExtVectorAddr(), CV,
962                                  Base.getQualifiers());
963}
964
965LValue CodeGenFunction::EmitMemberExpr(const MemberExpr *E) {
966  bool isUnion = false;
967  bool isIvar = false;
968  bool isNonGC = false;
969  Expr *BaseExpr = E->getBase();
970  llvm::Value *BaseValue = NULL;
971  unsigned CVRQualifiers=0;
972
973  // If this is s.x, emit s as an lvalue.  If it is s->x, emit s as a scalar.
974  if (E->isArrow()) {
975    BaseValue = EmitScalarExpr(BaseExpr);
976    const PointerType *PTy =
977      BaseExpr->getType()->getAsPointerType();
978    if (PTy->getPointeeType()->isUnionType())
979      isUnion = true;
980    CVRQualifiers = PTy->getPointeeType().getCVRQualifiers();
981  } else if (isa<ObjCPropertyRefExpr>(BaseExpr) ||
982             isa<ObjCKVCRefExpr>(BaseExpr)) {
983    RValue RV = EmitObjCPropertyGet(BaseExpr);
984    BaseValue = RV.getAggregateAddr();
985    if (BaseExpr->getType()->isUnionType())
986      isUnion = true;
987    CVRQualifiers = BaseExpr->getType().getCVRQualifiers();
988  } else {
989    LValue BaseLV = EmitLValue(BaseExpr);
990    if (BaseLV.isObjCIvar())
991      isIvar = true;
992    if (BaseLV.isNonGC())
993      isNonGC = true;
994    // FIXME: this isn't right for bitfields.
995    BaseValue = BaseLV.getAddress();
996    if (BaseExpr->getType()->isUnionType())
997      isUnion = true;
998    CVRQualifiers = BaseExpr->getType().getCVRQualifiers();
999  }
1000
1001  FieldDecl *Field = dyn_cast<FieldDecl>(E->getMemberDecl());
1002  // FIXME: Handle non-field member expressions
1003  assert(Field && "No code generation for non-field member references");
1004  LValue MemExpLV = EmitLValueForField(BaseValue, Field, isUnion,
1005                                       CVRQualifiers);
1006  LValue::SetObjCIvar(MemExpLV, isIvar);
1007  LValue::SetObjCNonGC(MemExpLV, isNonGC);
1008  return MemExpLV;
1009}
1010
1011LValue CodeGenFunction::EmitLValueForBitfield(llvm::Value* BaseValue,
1012                                              FieldDecl* Field,
1013                                              unsigned CVRQualifiers) {
1014   unsigned idx = CGM.getTypes().getLLVMFieldNo(Field);
1015  // FIXME: CodeGenTypes should expose a method to get the appropriate type for
1016  // FieldTy (the appropriate type is ABI-dependent).
1017  const llvm::Type *FieldTy =
1018    CGM.getTypes().ConvertTypeForMem(Field->getType());
1019  const llvm::PointerType *BaseTy =
1020  cast<llvm::PointerType>(BaseValue->getType());
1021  unsigned AS = BaseTy->getAddressSpace();
1022  BaseValue = Builder.CreateBitCast(BaseValue,
1023                                    llvm::PointerType::get(FieldTy, AS),
1024                                    "tmp");
1025  llvm::Value *V = Builder.CreateGEP(BaseValue,
1026                              llvm::ConstantInt::get(llvm::Type::Int32Ty, idx),
1027                              "tmp");
1028
1029  CodeGenTypes::BitFieldInfo bitFieldInfo =
1030    CGM.getTypes().getBitFieldInfo(Field);
1031  return LValue::MakeBitfield(V, bitFieldInfo.Begin, bitFieldInfo.Size,
1032                              Field->getType()->isSignedIntegerType(),
1033                            Field->getType().getCVRQualifiers()|CVRQualifiers);
1034}
1035
1036LValue CodeGenFunction::EmitLValueForField(llvm::Value* BaseValue,
1037                                           FieldDecl* Field,
1038                                           bool isUnion,
1039                                           unsigned CVRQualifiers)
1040{
1041  if (Field->isBitField())
1042    return EmitLValueForBitfield(BaseValue, Field, CVRQualifiers);
1043
1044  unsigned idx = CGM.getTypes().getLLVMFieldNo(Field);
1045  llvm::Value *V = Builder.CreateStructGEP(BaseValue, idx, "tmp");
1046
1047  // Match union field type.
1048  if (isUnion) {
1049    const llvm::Type *FieldTy =
1050      CGM.getTypes().ConvertTypeForMem(Field->getType());
1051    const llvm::PointerType * BaseTy =
1052      cast<llvm::PointerType>(BaseValue->getType());
1053    unsigned AS = BaseTy->getAddressSpace();
1054    V = Builder.CreateBitCast(V,
1055                              llvm::PointerType::get(FieldTy, AS),
1056                              "tmp");
1057  }
1058  if (Field->getType()->isReferenceType())
1059    V = Builder.CreateLoad(V, "tmp");
1060
1061  QualType::GCAttrTypes attr = QualType::GCNone;
1062  if (CGM.getLangOptions().ObjC1 &&
1063      CGM.getLangOptions().getGCMode() != LangOptions::NonGC) {
1064    QualType Ty = Field->getType();
1065    attr = Ty.getObjCGCAttr();
1066    if (attr != QualType::GCNone) {
1067      // __weak attribute on a field is ignored.
1068      if (attr == QualType::Weak)
1069        attr = QualType::GCNone;
1070    }
1071    else if (getContext().isObjCObjectPointerType(Ty))
1072      attr = QualType::Strong;
1073  }
1074  LValue LV =
1075    LValue::MakeAddr(V,
1076                     Field->getType().getCVRQualifiers()|CVRQualifiers,
1077                     attr);
1078  return LV;
1079}
1080
1081LValue CodeGenFunction::EmitCompoundLiteralLValue(const CompoundLiteralExpr* E){
1082  const llvm::Type *LTy = ConvertType(E->getType());
1083  llvm::Value *DeclPtr = CreateTempAlloca(LTy, ".compoundliteral");
1084
1085  const Expr* InitExpr = E->getInitializer();
1086  LValue Result = LValue::MakeAddr(DeclPtr, E->getType().getCVRQualifiers());
1087
1088  if (E->getType()->isComplexType()) {
1089    EmitComplexExprIntoAddr(InitExpr, DeclPtr, false);
1090  } else if (hasAggregateLLVMType(E->getType())) {
1091    EmitAnyExpr(InitExpr, DeclPtr, false);
1092  } else {
1093    EmitStoreThroughLValue(EmitAnyExpr(InitExpr), Result, E->getType());
1094  }
1095
1096  return Result;
1097}
1098
1099LValue CodeGenFunction::EmitConditionalOperator(const ConditionalOperator* E) {
1100  // We don't handle vectors yet.
1101  if (E->getType()->isVectorType())
1102    return EmitUnsupportedLValue(E, "conditional operator");
1103
1104  // ?: here should be an aggregate.
1105  assert((hasAggregateLLVMType(E->getType()) &&
1106          !E->getType()->isAnyComplexType()) &&
1107         "Unexpected conditional operator!");
1108
1109  llvm::Value *Temp = CreateTempAlloca(ConvertType(E->getType()));
1110  EmitAggExpr(E, Temp, false);
1111
1112  return LValue::MakeAddr(Temp, E->getType().getCVRQualifiers(),
1113                          getContext().getObjCGCAttrKind(E->getType()));
1114
1115}
1116
1117/// EmitCastLValue - Casts are never lvalues.  If a cast is needed by the code
1118/// generator in an lvalue context, then it must mean that we need the address
1119/// of an aggregate in order to access one of its fields.  This can happen for
1120/// all the reasons that casts are permitted with aggregate result, including
1121/// noop aggregate casts, and cast from scalar to union.
1122LValue CodeGenFunction::EmitCastLValue(const CastExpr *E) {
1123  // If this is an aggregate-to-aggregate cast, just use the input's address as
1124  // the lvalue.
1125  if (getContext().hasSameUnqualifiedType(E->getType(),
1126                                          E->getSubExpr()->getType()))
1127    return EmitLValue(E->getSubExpr());
1128
1129  // Otherwise, we must have a cast from scalar to union.
1130  assert(E->getType()->isUnionType() && "Expected scalar-to-union cast");
1131
1132  // Casts are only lvalues when the source and destination types are the same.
1133  llvm::Value *Temp = CreateTempAlloca(ConvertType(E->getType()));
1134  EmitAnyExpr(E->getSubExpr(), Temp, false);
1135
1136  return LValue::MakeAddr(Temp, E->getType().getCVRQualifiers(),
1137                          getContext().getObjCGCAttrKind(E->getType()));
1138}
1139
1140//===--------------------------------------------------------------------===//
1141//                             Expression Emission
1142//===--------------------------------------------------------------------===//
1143
1144
1145RValue CodeGenFunction::EmitCallExpr(const CallExpr *E) {
1146  // Builtins never have block type.
1147  if (E->getCallee()->getType()->isBlockPointerType())
1148    return EmitBlockCallExpr(E);
1149
1150  if (const CXXMemberCallExpr *CE = dyn_cast<CXXMemberCallExpr>(E))
1151    return EmitCXXMemberCallExpr(CE);
1152
1153  const Decl *TargetDecl = 0;
1154  if (const ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(E->getCallee())) {
1155    if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(CE->getSubExpr())) {
1156      TargetDecl = DRE->getDecl();
1157      if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(TargetDecl))
1158        if (unsigned builtinID = FD->getBuiltinID(getContext()))
1159          return EmitBuiltinExpr(FD, builtinID, E);
1160    }
1161  }
1162
1163  if (const CXXOperatorCallExpr *CE = dyn_cast<CXXOperatorCallExpr>(E))
1164    if (const CXXMethodDecl *MD = dyn_cast_or_null<CXXMethodDecl>(TargetDecl))
1165      return EmitCXXOperatorMemberCallExpr(CE, MD);
1166
1167  llvm::Value *Callee = EmitScalarExpr(E->getCallee());
1168  return EmitCall(Callee, E->getCallee()->getType(),
1169                  E->arg_begin(), E->arg_end(), TargetDecl);
1170}
1171
1172LValue CodeGenFunction::EmitBinaryOperatorLValue(const BinaryOperator *E) {
1173  // Comma expressions just emit their LHS then their RHS as an l-value.
1174  if (E->getOpcode() == BinaryOperator::Comma) {
1175    EmitAnyExpr(E->getLHS());
1176    return EmitLValue(E->getRHS());
1177  }
1178
1179  // Can only get l-value for binary operator expressions which are a
1180  // simple assignment of aggregate type.
1181  if (E->getOpcode() != BinaryOperator::Assign)
1182    return EmitUnsupportedLValue(E, "binary l-value expression");
1183
1184  llvm::Value *Temp = CreateTempAlloca(ConvertType(E->getType()));
1185  EmitAggExpr(E, Temp, false);
1186  // FIXME: Are these qualifiers correct?
1187  return LValue::MakeAddr(Temp, E->getType().getCVRQualifiers(),
1188                          getContext().getObjCGCAttrKind(E->getType()));
1189}
1190
1191LValue CodeGenFunction::EmitCallExprLValue(const CallExpr *E) {
1192  RValue RV = EmitCallExpr(E);
1193
1194  if (RV.isScalar()) {
1195    assert(E->getCallReturnType()->isReferenceType() &&
1196           "Can't have a scalar return unless the return type is a "
1197           "reference type!");
1198
1199    return LValue::MakeAddr(RV.getScalarVal(), E->getType().getCVRQualifiers(),
1200                            getContext().getObjCGCAttrKind(E->getType()));
1201  }
1202
1203  return LValue::MakeAddr(RV.getAggregateAddr(),
1204                          E->getType().getCVRQualifiers(),
1205                          getContext().getObjCGCAttrKind(E->getType()));
1206}
1207
1208LValue CodeGenFunction::EmitVAArgExprLValue(const VAArgExpr *E) {
1209  // FIXME: This shouldn't require another copy.
1210  llvm::Value *Temp = CreateTempAlloca(ConvertType(E->getType()));
1211  EmitAggExpr(E, Temp, false);
1212  return LValue::MakeAddr(Temp, E->getType().getCVRQualifiers());
1213}
1214
1215LValue
1216CodeGenFunction::EmitCXXConditionDeclLValue(const CXXConditionDeclExpr *E) {
1217  EmitLocalBlockVarDecl(*E->getVarDecl());
1218  return EmitDeclRefLValue(E);
1219}
1220
1221LValue CodeGenFunction::EmitCXXConstructLValue(const CXXConstructExpr *E) {
1222  llvm::Value *Temp = CreateTempAlloca(ConvertTypeForMem(E->getType()), "tmp");
1223  EmitCXXConstructExpr(Temp, E);
1224  return LValue::MakeAddr(Temp, E->getType().getCVRQualifiers());
1225}
1226
1227LValue
1228CodeGenFunction::EmitCXXBindTemporaryLValue(const CXXBindTemporaryExpr *E) {
1229  LValue LV = EmitLValue(E->getSubExpr());
1230
1231  PushCXXTemporary(E->getTemporary(), LV.getAddress());
1232
1233  return LV;
1234}
1235
1236LValue CodeGenFunction::EmitObjCMessageExprLValue(const ObjCMessageExpr *E) {
1237  // Can only get l-value for message expression returning aggregate type
1238  RValue RV = EmitObjCMessageExpr(E);
1239  // FIXME: can this be volatile?
1240  return LValue::MakeAddr(RV.getAggregateAddr(),
1241                          E->getType().getCVRQualifiers(),
1242                          getContext().getObjCGCAttrKind(E->getType()));
1243}
1244
1245llvm::Value *CodeGenFunction::EmitIvarOffset(const ObjCInterfaceDecl *Interface,
1246                                             const ObjCIvarDecl *Ivar) {
1247  return CGM.getObjCRuntime().EmitIvarOffset(*this, Interface, Ivar);
1248}
1249
1250LValue CodeGenFunction::EmitLValueForIvar(QualType ObjectTy,
1251                                          llvm::Value *BaseValue,
1252                                          const ObjCIvarDecl *Ivar,
1253                                          unsigned CVRQualifiers) {
1254  return CGM.getObjCRuntime().EmitObjCValueForIvar(*this, ObjectTy, BaseValue,
1255                                                   Ivar, CVRQualifiers);
1256}
1257
1258LValue CodeGenFunction::EmitObjCIvarRefLValue(const ObjCIvarRefExpr *E) {
1259  // FIXME: A lot of the code below could be shared with EmitMemberExpr.
1260  llvm::Value *BaseValue = 0;
1261  const Expr *BaseExpr = E->getBase();
1262  unsigned CVRQualifiers = 0;
1263  QualType ObjectTy;
1264  if (E->isArrow()) {
1265    BaseValue = EmitScalarExpr(BaseExpr);
1266    ObjectTy = BaseExpr->getType()->getPointeeType();
1267    CVRQualifiers = ObjectTy.getCVRQualifiers();
1268  } else {
1269    LValue BaseLV = EmitLValue(BaseExpr);
1270    // FIXME: this isn't right for bitfields.
1271    BaseValue = BaseLV.getAddress();
1272    ObjectTy = BaseExpr->getType();
1273    CVRQualifiers = ObjectTy.getCVRQualifiers();
1274  }
1275
1276  return EmitLValueForIvar(ObjectTy, BaseValue, E->getDecl(), CVRQualifiers);
1277}
1278
1279LValue
1280CodeGenFunction::EmitObjCPropertyRefLValue(const ObjCPropertyRefExpr *E) {
1281  // This is a special l-value that just issues sends when we load or
1282  // store through it.
1283  return LValue::MakePropertyRef(E, E->getType().getCVRQualifiers());
1284}
1285
1286LValue
1287CodeGenFunction::EmitObjCKVCRefLValue(const ObjCKVCRefExpr *E) {
1288  // This is a special l-value that just issues sends when we load or
1289  // store through it.
1290  return LValue::MakeKVCRef(E, E->getType().getCVRQualifiers());
1291}
1292
1293LValue
1294CodeGenFunction::EmitObjCSuperExprLValue(const ObjCSuperExpr *E) {
1295  return EmitUnsupportedLValue(E, "use of super");
1296}
1297
1298LValue CodeGenFunction::EmitStmtExprLValue(const StmtExpr *E) {
1299
1300  // Can only get l-value for message expression returning aggregate type
1301  RValue RV = EmitAnyExprToTemp(E);
1302  // FIXME: can this be volatile?
1303  return LValue::MakeAddr(RV.getAggregateAddr(),
1304                          E->getType().getCVRQualifiers(),
1305                          getContext().getObjCGCAttrKind(E->getType()));
1306}
1307
1308
1309RValue CodeGenFunction::EmitCall(llvm::Value *Callee, QualType CalleeType,
1310                                 CallExpr::const_arg_iterator ArgBeg,
1311                                 CallExpr::const_arg_iterator ArgEnd,
1312                                 const Decl *TargetDecl) {
1313  // Get the actual function type. The callee type will always be a
1314  // pointer to function type or a block pointer type.
1315  assert(CalleeType->isFunctionPointerType() &&
1316         "Call must have function pointer type!");
1317
1318  QualType FnType = CalleeType->getAsPointerType()->getPointeeType();
1319  QualType ResultType = FnType->getAsFunctionType()->getResultType();
1320
1321  CallArgList Args;
1322  EmitCallArgs(Args, FnType->getAsFunctionProtoType(), ArgBeg, ArgEnd);
1323
1324  return EmitCall(CGM.getTypes().getFunctionInfo(ResultType, Args),
1325                  Callee, Args, TargetDecl);
1326}
1327