CGExprAgg.cpp revision 200583 
1//===--- CGExprAgg.cpp - Emit LLVM Code from Aggregate 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 Aggregate Expr nodes as LLVM code.
11//
12//===----------------------------------------------------------------------===//
13
14#include "CodeGenFunction.h"
15#include "CodeGenModule.h"
16#include "CGObjCRuntime.h"
17#include "clang/AST/ASTContext.h"
18#include "clang/AST/DeclCXX.h"
19#include "clang/AST/StmtVisitor.h"
20#include "llvm/Constants.h"
21#include "llvm/Function.h"
22#include "llvm/GlobalVariable.h"
23#include "llvm/Intrinsics.h"
24using namespace clang;
25using namespace CodeGen;
26
27//===----------------------------------------------------------------------===//
28//                        Aggregate Expression Emitter
29//===----------------------------------------------------------------------===//
30
31namespace  {
32class AggExprEmitter : public StmtVisitor<AggExprEmitter> {
33  CodeGenFunction &CGF;
34  CGBuilderTy &Builder;
35  llvm::Value *DestPtr;
36  bool VolatileDest;
37  bool IgnoreResult;
38  bool IsInitializer;
39  bool RequiresGCollection;
40public:
41  AggExprEmitter(CodeGenFunction &cgf, llvm::Value *destPtr, bool v,
42                 bool ignore, bool isinit, bool requiresGCollection)
43    : CGF(cgf), Builder(CGF.Builder),
44      DestPtr(destPtr), VolatileDest(v), IgnoreResult(ignore),
45      IsInitializer(isinit), RequiresGCollection(requiresGCollection) {
46  }
47
48  //===--------------------------------------------------------------------===//
49  //                               Utilities
50  //===--------------------------------------------------------------------===//
51
52  /// EmitAggLoadOfLValue - Given an expression with aggregate type that
53  /// represents a value lvalue, this method emits the address of the lvalue,
54  /// then loads the result into DestPtr.
55  void EmitAggLoadOfLValue(const Expr *E);
56
57  /// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired.
58  void EmitFinalDestCopy(const Expr *E, LValue Src, bool Ignore = false);
59  void EmitFinalDestCopy(const Expr *E, RValue Src, bool Ignore = false);
60
61  //===--------------------------------------------------------------------===//
62  //                            Visitor Methods
63  //===--------------------------------------------------------------------===//
64
65  void VisitStmt(Stmt *S) {
66    CGF.ErrorUnsupported(S, "aggregate expression");
67  }
68  void VisitParenExpr(ParenExpr *PE) { Visit(PE->getSubExpr()); }
69  void VisitUnaryExtension(UnaryOperator *E) { Visit(E->getSubExpr()); }
70
71  // l-values.
72  void VisitDeclRefExpr(DeclRefExpr *DRE) { EmitAggLoadOfLValue(DRE); }
73  void VisitMemberExpr(MemberExpr *ME) { EmitAggLoadOfLValue(ME); }
74  void VisitUnaryDeref(UnaryOperator *E) { EmitAggLoadOfLValue(E); }
75  void VisitStringLiteral(StringLiteral *E) { EmitAggLoadOfLValue(E); }
76  void VisitCompoundLiteralExpr(CompoundLiteralExpr *E) {
77    EmitAggLoadOfLValue(E);
78  }
79  void VisitArraySubscriptExpr(ArraySubscriptExpr *E) {
80    EmitAggLoadOfLValue(E);
81  }
82  void VisitBlockDeclRefExpr(const BlockDeclRefExpr *E) {
83    EmitAggLoadOfLValue(E);
84  }
85  void VisitPredefinedExpr(const PredefinedExpr *E) {
86    EmitAggLoadOfLValue(E);
87  }
88
89  // Operators.
90  void VisitCastExpr(CastExpr *E);
91  void VisitCallExpr(const CallExpr *E);
92  void VisitStmtExpr(const StmtExpr *E);
93  void VisitBinaryOperator(const BinaryOperator *BO);
94  void VisitPointerToDataMemberBinaryOperator(const BinaryOperator *BO);
95  void VisitBinAssign(const BinaryOperator *E);
96  void VisitBinComma(const BinaryOperator *E);
97  void VisitUnaryAddrOf(const UnaryOperator *E);
98
99  void VisitObjCMessageExpr(ObjCMessageExpr *E);
100  void VisitObjCIvarRefExpr(ObjCIvarRefExpr *E) {
101    EmitAggLoadOfLValue(E);
102  }
103  void VisitObjCPropertyRefExpr(ObjCPropertyRefExpr *E);
104  void VisitObjCImplicitSetterGetterRefExpr(ObjCImplicitSetterGetterRefExpr *E);
105
106  void VisitConditionalOperator(const ConditionalOperator *CO);
107  void VisitChooseExpr(const ChooseExpr *CE);
108  void VisitInitListExpr(InitListExpr *E);
109  void VisitCXXDefaultArgExpr(CXXDefaultArgExpr *DAE) {
110    Visit(DAE->getExpr());
111  }
112  void VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E);
113  void VisitCXXConstructExpr(const CXXConstructExpr *E);
114  void VisitCXXExprWithTemporaries(CXXExprWithTemporaries *E);
115  void VisitCXXZeroInitValueExpr(CXXZeroInitValueExpr *E);
116  void VisitCXXTypeidExpr(CXXTypeidExpr *E) { EmitAggLoadOfLValue(E); }
117
118  void VisitVAArgExpr(VAArgExpr *E);
119
120  void EmitInitializationToLValue(Expr *E, LValue Address);
121  void EmitNullInitializationToLValue(LValue Address, QualType T);
122  //  case Expr::ChooseExprClass:
123  void VisitCXXThrowExpr(const CXXThrowExpr *E) { CGF.EmitCXXThrowExpr(E); }
124};
125}  // end anonymous namespace.
126
127//===----------------------------------------------------------------------===//
128//                                Utilities
129//===----------------------------------------------------------------------===//
130
131/// EmitAggLoadOfLValue - Given an expression with aggregate type that
132/// represents a value lvalue, this method emits the address of the lvalue,
133/// then loads the result into DestPtr.
134void AggExprEmitter::EmitAggLoadOfLValue(const Expr *E) {
135  LValue LV = CGF.EmitLValue(E);
136  EmitFinalDestCopy(E, LV);
137}
138
139/// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired.
140void AggExprEmitter::EmitFinalDestCopy(const Expr *E, RValue Src, bool Ignore) {
141  assert(Src.isAggregate() && "value must be aggregate value!");
142
143  // If the result is ignored, don't copy from the value.
144  if (DestPtr == 0) {
145    if (!Src.isVolatileQualified() || (IgnoreResult && Ignore))
146      return;
147    // If the source is volatile, we must read from it; to do that, we need
148    // some place to put it.
149    DestPtr = CGF.CreateTempAlloca(CGF.ConvertType(E->getType()), "agg.tmp");
150  }
151
152  if (RequiresGCollection) {
153    CGF.CGM.getObjCRuntime().EmitGCMemmoveCollectable(CGF,
154                                              DestPtr, Src.getAggregateAddr(),
155                                              E->getType());
156    return;
157  }
158  // If the result of the assignment is used, copy the LHS there also.
159  // FIXME: Pass VolatileDest as well.  I think we also need to merge volatile
160  // from the source as well, as we can't eliminate it if either operand
161  // is volatile, unless copy has volatile for both source and destination..
162  CGF.EmitAggregateCopy(DestPtr, Src.getAggregateAddr(), E->getType(),
163                        VolatileDest|Src.isVolatileQualified());
164}
165
166/// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired.
167void AggExprEmitter::EmitFinalDestCopy(const Expr *E, LValue Src, bool Ignore) {
168  assert(Src.isSimple() && "Can't have aggregate bitfield, vector, etc");
169
170  EmitFinalDestCopy(E, RValue::getAggregate(Src.getAddress(),
171                                            Src.isVolatileQualified()),
172                    Ignore);
173}
174
175//===----------------------------------------------------------------------===//
176//                            Visitor Methods
177//===----------------------------------------------------------------------===//
178
179void AggExprEmitter::VisitCastExpr(CastExpr *E) {
180  switch (E->getCastKind()) {
181  default: assert(0 && "Unhandled cast kind!");
182
183  case CastExpr::CK_ToUnion: {
184    // GCC union extension
185    QualType PtrTy =
186    CGF.getContext().getPointerType(E->getSubExpr()->getType());
187    llvm::Value *CastPtr = Builder.CreateBitCast(DestPtr,
188                                                 CGF.ConvertType(PtrTy));
189    EmitInitializationToLValue(E->getSubExpr(),
190                               LValue::MakeAddr(CastPtr, Qualifiers()));
191    break;
192  }
193
194  // FIXME: Remove the CK_Unknown check here.
195  case CastExpr::CK_Unknown:
196  case CastExpr::CK_NoOp:
197  case CastExpr::CK_UserDefinedConversion:
198  case CastExpr::CK_ConstructorConversion:
199    assert(CGF.getContext().hasSameUnqualifiedType(E->getSubExpr()->getType(),
200                                                   E->getType()) &&
201           "Implicit cast types must be compatible");
202    Visit(E->getSubExpr());
203    break;
204
205  case CastExpr::CK_NullToMemberPointer: {
206    const llvm::Type *PtrDiffTy =
207      CGF.ConvertType(CGF.getContext().getPointerDiffType());
208
209    llvm::Value *NullValue = llvm::Constant::getNullValue(PtrDiffTy);
210    llvm::Value *Ptr = Builder.CreateStructGEP(DestPtr, 0, "ptr");
211    Builder.CreateStore(NullValue, Ptr, VolatileDest);
212
213    llvm::Value *Adj = Builder.CreateStructGEP(DestPtr, 1, "adj");
214    Builder.CreateStore(NullValue, Adj, VolatileDest);
215
216    break;
217  }
218
219  case CastExpr::CK_BitCast: {
220    // This must be a member function pointer cast.
221    Visit(E->getSubExpr());
222    break;
223  }
224
225  case CastExpr::CK_DerivedToBaseMemberPointer:
226  case CastExpr::CK_BaseToDerivedMemberPointer: {
227    QualType SrcType = E->getSubExpr()->getType();
228
229    llvm::Value *Src = CGF.CreateTempAlloca(CGF.ConvertTypeForMem(SrcType),
230                                            "tmp");
231    CGF.EmitAggExpr(E->getSubExpr(), Src, SrcType.isVolatileQualified());
232
233    llvm::Value *SrcPtr = Builder.CreateStructGEP(Src, 0, "src.ptr");
234    SrcPtr = Builder.CreateLoad(SrcPtr);
235
236    llvm::Value *SrcAdj = Builder.CreateStructGEP(Src, 1, "src.adj");
237    SrcAdj = Builder.CreateLoad(SrcAdj);
238
239    llvm::Value *DstPtr = Builder.CreateStructGEP(DestPtr, 0, "dst.ptr");
240    Builder.CreateStore(SrcPtr, DstPtr, VolatileDest);
241
242    llvm::Value *DstAdj = Builder.CreateStructGEP(DestPtr, 1, "dst.adj");
243
244    // Now See if we need to update the adjustment.
245    const CXXRecordDecl *BaseDecl =
246      cast<CXXRecordDecl>(SrcType->getAs<MemberPointerType>()->
247                          getClass()->getAs<RecordType>()->getDecl());
248    const CXXRecordDecl *DerivedDecl =
249      cast<CXXRecordDecl>(E->getType()->getAs<MemberPointerType>()->
250                          getClass()->getAs<RecordType>()->getDecl());
251    if (E->getCastKind() == CastExpr::CK_DerivedToBaseMemberPointer)
252      std::swap(DerivedDecl, BaseDecl);
253
254    llvm::Constant *Adj = CGF.CGM.GetCXXBaseClassOffset(DerivedDecl, BaseDecl);
255    if (Adj) {
256      if (E->getCastKind() == CastExpr::CK_DerivedToBaseMemberPointer)
257        SrcAdj = Builder.CreateSub(SrcAdj, Adj, "adj");
258      else
259        SrcAdj = Builder.CreateAdd(SrcAdj, Adj, "adj");
260    }
261
262    Builder.CreateStore(SrcAdj, DstAdj, VolatileDest);
263    break;
264  }
265  }
266}
267
268void AggExprEmitter::VisitCallExpr(const CallExpr *E) {
269  if (E->getCallReturnType()->isReferenceType()) {
270    EmitAggLoadOfLValue(E);
271    return;
272  }
273
274  RValue RV = CGF.EmitCallExpr(E);
275  EmitFinalDestCopy(E, RV);
276}
277
278void AggExprEmitter::VisitObjCMessageExpr(ObjCMessageExpr *E) {
279  RValue RV = CGF.EmitObjCMessageExpr(E);
280  EmitFinalDestCopy(E, RV);
281}
282
283void AggExprEmitter::VisitObjCPropertyRefExpr(ObjCPropertyRefExpr *E) {
284  RValue RV = CGF.EmitObjCPropertyGet(E);
285  EmitFinalDestCopy(E, RV);
286}
287
288void AggExprEmitter::VisitObjCImplicitSetterGetterRefExpr(
289                                   ObjCImplicitSetterGetterRefExpr *E) {
290  RValue RV = CGF.EmitObjCPropertyGet(E);
291  EmitFinalDestCopy(E, RV);
292}
293
294void AggExprEmitter::VisitBinComma(const BinaryOperator *E) {
295  CGF.EmitAnyExpr(E->getLHS(), 0, false, true);
296  CGF.EmitAggExpr(E->getRHS(), DestPtr, VolatileDest,
297                  /*IgnoreResult=*/false, IsInitializer);
298}
299
300void AggExprEmitter::VisitUnaryAddrOf(const UnaryOperator *E) {
301  // We have a member function pointer.
302  const MemberPointerType *MPT = E->getType()->getAs<MemberPointerType>();
303  (void) MPT;
304  assert(MPT->getPointeeType()->isFunctionProtoType() &&
305         "Unexpected member pointer type!");
306
307  const DeclRefExpr *DRE = cast<DeclRefExpr>(E->getSubExpr());
308  const CXXMethodDecl *MD = cast<CXXMethodDecl>(DRE->getDecl());
309
310  const llvm::Type *PtrDiffTy =
311    CGF.ConvertType(CGF.getContext().getPointerDiffType());
312
313  llvm::Value *DstPtr = Builder.CreateStructGEP(DestPtr, 0, "dst.ptr");
314  llvm::Value *FuncPtr;
315
316  if (MD->isVirtual()) {
317    int64_t Index =
318      CGF.CGM.getVtableInfo().getMethodVtableIndex(MD);
319
320    FuncPtr = llvm::ConstantInt::get(PtrDiffTy, Index + 1);
321  } else {
322    FuncPtr = llvm::ConstantExpr::getPtrToInt(CGF.CGM.GetAddrOfFunction(MD),
323                                              PtrDiffTy);
324  }
325  Builder.CreateStore(FuncPtr, DstPtr, VolatileDest);
326
327  llvm::Value *AdjPtr = Builder.CreateStructGEP(DestPtr, 1, "dst.adj");
328
329  // The adjustment will always be 0.
330  Builder.CreateStore(llvm::ConstantInt::get(PtrDiffTy, 0), AdjPtr,
331                      VolatileDest);
332}
333
334void AggExprEmitter::VisitStmtExpr(const StmtExpr *E) {
335  CGF.EmitCompoundStmt(*E->getSubStmt(), true, DestPtr, VolatileDest);
336}
337
338void AggExprEmitter::VisitBinaryOperator(const BinaryOperator *E) {
339  if (E->getOpcode() == BinaryOperator::PtrMemD ||
340      E->getOpcode() == BinaryOperator::PtrMemI)
341    VisitPointerToDataMemberBinaryOperator(E);
342  else
343    CGF.ErrorUnsupported(E, "aggregate binary expression");
344}
345
346void AggExprEmitter::VisitPointerToDataMemberBinaryOperator(
347                                                    const BinaryOperator *E) {
348  LValue LV = CGF.EmitPointerToDataMemberBinaryExpr(E);
349  EmitFinalDestCopy(E, LV);
350}
351
352void AggExprEmitter::VisitBinAssign(const BinaryOperator *E) {
353  // For an assignment to work, the value on the right has
354  // to be compatible with the value on the left.
355  assert(CGF.getContext().hasSameUnqualifiedType(E->getLHS()->getType(),
356                                                 E->getRHS()->getType())
357         && "Invalid assignment");
358  LValue LHS = CGF.EmitLValue(E->getLHS());
359
360  // We have to special case property setters, otherwise we must have
361  // a simple lvalue (no aggregates inside vectors, bitfields).
362  if (LHS.isPropertyRef()) {
363    llvm::Value *AggLoc = DestPtr;
364    if (!AggLoc)
365      AggLoc = CGF.CreateTempAlloca(CGF.ConvertType(E->getRHS()->getType()));
366    CGF.EmitAggExpr(E->getRHS(), AggLoc, VolatileDest);
367    CGF.EmitObjCPropertySet(LHS.getPropertyRefExpr(),
368                            RValue::getAggregate(AggLoc, VolatileDest));
369  } else if (LHS.isKVCRef()) {
370    llvm::Value *AggLoc = DestPtr;
371    if (!AggLoc)
372      AggLoc = CGF.CreateTempAlloca(CGF.ConvertType(E->getRHS()->getType()));
373    CGF.EmitAggExpr(E->getRHS(), AggLoc, VolatileDest);
374    CGF.EmitObjCPropertySet(LHS.getKVCRefExpr(),
375                            RValue::getAggregate(AggLoc, VolatileDest));
376  } else {
377    bool RequiresGCollection = false;
378    if (CGF.getContext().getLangOptions().NeXTRuntime) {
379      QualType LHSTy = E->getLHS()->getType();
380      if (const RecordType *FDTTy = LHSTy.getTypePtr()->getAs<RecordType>())
381        RequiresGCollection = FDTTy->getDecl()->hasObjectMember();
382    }
383    // Codegen the RHS so that it stores directly into the LHS.
384    CGF.EmitAggExpr(E->getRHS(), LHS.getAddress(), LHS.isVolatileQualified(),
385                    false, false, RequiresGCollection);
386    EmitFinalDestCopy(E, LHS, true);
387  }
388}
389
390void AggExprEmitter::VisitConditionalOperator(const ConditionalOperator *E) {
391  llvm::BasicBlock *LHSBlock = CGF.createBasicBlock("cond.true");
392  llvm::BasicBlock *RHSBlock = CGF.createBasicBlock("cond.false");
393  llvm::BasicBlock *ContBlock = CGF.createBasicBlock("cond.end");
394
395  llvm::Value *Cond = CGF.EvaluateExprAsBool(E->getCond());
396  Builder.CreateCondBr(Cond, LHSBlock, RHSBlock);
397
398  CGF.StartConditionalBranch();
399  CGF.EmitBlock(LHSBlock);
400
401  // Handle the GNU extension for missing LHS.
402  assert(E->getLHS() && "Must have LHS for aggregate value");
403
404  Visit(E->getLHS());
405  CGF.FinishConditionalBranch();
406  CGF.EmitBranch(ContBlock);
407
408  CGF.StartConditionalBranch();
409  CGF.EmitBlock(RHSBlock);
410
411  Visit(E->getRHS());
412  CGF.FinishConditionalBranch();
413  CGF.EmitBranch(ContBlock);
414
415  CGF.EmitBlock(ContBlock);
416}
417
418void AggExprEmitter::VisitChooseExpr(const ChooseExpr *CE) {
419  Visit(CE->getChosenSubExpr(CGF.getContext()));
420}
421
422void AggExprEmitter::VisitVAArgExpr(VAArgExpr *VE) {
423  llvm::Value *ArgValue = CGF.EmitVAListRef(VE->getSubExpr());
424  llvm::Value *ArgPtr = CGF.EmitVAArg(ArgValue, VE->getType());
425
426  if (!ArgPtr) {
427    CGF.ErrorUnsupported(VE, "aggregate va_arg expression");
428    return;
429  }
430
431  EmitFinalDestCopy(VE, LValue::MakeAddr(ArgPtr, Qualifiers()));
432}
433
434void AggExprEmitter::VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E) {
435  llvm::Value *Val = DestPtr;
436
437  if (!Val) {
438    // Create a temporary variable.
439    Val = CGF.CreateTempAlloca(CGF.ConvertTypeForMem(E->getType()), "tmp");
440
441    // FIXME: volatile
442    CGF.EmitAggExpr(E->getSubExpr(), Val, false);
443  } else
444    Visit(E->getSubExpr());
445
446  // Don't make this a live temporary if we're emitting an initializer expr.
447  if (!IsInitializer)
448    CGF.PushCXXTemporary(E->getTemporary(), Val);
449}
450
451void
452AggExprEmitter::VisitCXXConstructExpr(const CXXConstructExpr *E) {
453  llvm::Value *Val = DestPtr;
454
455  if (!Val) {
456    // Create a temporary variable.
457    Val = CGF.CreateTempAlloca(CGF.ConvertTypeForMem(E->getType()), "tmp");
458  }
459
460  CGF.EmitCXXConstructExpr(Val, E);
461}
462
463void AggExprEmitter::VisitCXXExprWithTemporaries(CXXExprWithTemporaries *E) {
464  CGF.EmitCXXExprWithTemporaries(E, DestPtr, VolatileDest, IsInitializer);
465}
466
467void AggExprEmitter::VisitCXXZeroInitValueExpr(CXXZeroInitValueExpr *E) {
468  LValue lvalue = LValue::MakeAddr(DestPtr, Qualifiers());
469  EmitNullInitializationToLValue(lvalue, E->getType());
470}
471
472void AggExprEmitter::EmitInitializationToLValue(Expr* E, LValue LV) {
473  // FIXME: Ignore result?
474  // FIXME: Are initializers affected by volatile?
475  if (isa<ImplicitValueInitExpr>(E)) {
476    EmitNullInitializationToLValue(LV, E->getType());
477  } else if (E->getType()->isComplexType()) {
478    CGF.EmitComplexExprIntoAddr(E, LV.getAddress(), false);
479  } else if (CGF.hasAggregateLLVMType(E->getType())) {
480    CGF.EmitAnyExpr(E, LV.getAddress(), false);
481  } else {
482    CGF.EmitStoreThroughLValue(CGF.EmitAnyExpr(E), LV, E->getType());
483  }
484}
485
486void AggExprEmitter::EmitNullInitializationToLValue(LValue LV, QualType T) {
487  if (!CGF.hasAggregateLLVMType(T)) {
488    // For non-aggregates, we can store zero
489    llvm::Value *Null = llvm::Constant::getNullValue(CGF.ConvertType(T));
490    CGF.EmitStoreThroughLValue(RValue::get(Null), LV, T);
491  } else {
492    // Otherwise, just memset the whole thing to zero.  This is legal
493    // because in LLVM, all default initializers are guaranteed to have a
494    // bit pattern of all zeros.
495    // FIXME: That isn't true for member pointers!
496    // There's a potential optimization opportunity in combining
497    // memsets; that would be easy for arrays, but relatively
498    // difficult for structures with the current code.
499    CGF.EmitMemSetToZero(LV.getAddress(), T);
500  }
501}
502
503void AggExprEmitter::VisitInitListExpr(InitListExpr *E) {
504#if 0
505  // FIXME: Assess perf here?  Figure out what cases are worth optimizing here
506  // (Length of globals? Chunks of zeroed-out space?).
507  //
508  // If we can, prefer a copy from a global; this is a lot less code for long
509  // globals, and it's easier for the current optimizers to analyze.
510  if (llvm::Constant* C = CGF.CGM.EmitConstantExpr(E, E->getType(), &CGF)) {
511    llvm::GlobalVariable* GV =
512    new llvm::GlobalVariable(CGF.CGM.getModule(), C->getType(), true,
513                             llvm::GlobalValue::InternalLinkage, C, "");
514    EmitFinalDestCopy(E, LValue::MakeAddr(GV, Qualifiers()));
515    return;
516  }
517#endif
518  if (E->hadArrayRangeDesignator()) {
519    CGF.ErrorUnsupported(E, "GNU array range designator extension");
520  }
521
522  // Handle initialization of an array.
523  if (E->getType()->isArrayType()) {
524    const llvm::PointerType *APType =
525      cast<llvm::PointerType>(DestPtr->getType());
526    const llvm::ArrayType *AType =
527      cast<llvm::ArrayType>(APType->getElementType());
528
529    uint64_t NumInitElements = E->getNumInits();
530
531    if (E->getNumInits() > 0) {
532      QualType T1 = E->getType();
533      QualType T2 = E->getInit(0)->getType();
534      if (CGF.getContext().hasSameUnqualifiedType(T1, T2)) {
535        EmitAggLoadOfLValue(E->getInit(0));
536        return;
537      }
538    }
539
540    uint64_t NumArrayElements = AType->getNumElements();
541    QualType ElementType = CGF.getContext().getCanonicalType(E->getType());
542    ElementType = CGF.getContext().getAsArrayType(ElementType)->getElementType();
543
544    // FIXME: were we intentionally ignoring address spaces and GC attributes?
545    Qualifiers Quals = CGF.MakeQualifiers(ElementType);
546
547    for (uint64_t i = 0; i != NumArrayElements; ++i) {
548      llvm::Value *NextVal = Builder.CreateStructGEP(DestPtr, i, ".array");
549      if (i < NumInitElements)
550        EmitInitializationToLValue(E->getInit(i),
551                                   LValue::MakeAddr(NextVal, Quals));
552      else
553        EmitNullInitializationToLValue(LValue::MakeAddr(NextVal, Quals),
554                                       ElementType);
555    }
556    return;
557  }
558
559  assert(E->getType()->isRecordType() && "Only support structs/unions here!");
560
561  // Do struct initialization; this code just sets each individual member
562  // to the approprate value.  This makes bitfield support automatic;
563  // the disadvantage is that the generated code is more difficult for
564  // the optimizer, especially with bitfields.
565  unsigned NumInitElements = E->getNumInits();
566  RecordDecl *SD = E->getType()->getAs<RecordType>()->getDecl();
567  unsigned CurInitVal = 0;
568
569  if (E->getType()->isUnionType()) {
570    // Only initialize one field of a union. The field itself is
571    // specified by the initializer list.
572    if (!E->getInitializedFieldInUnion()) {
573      // Empty union; we have nothing to do.
574
575#ifndef NDEBUG
576      // Make sure that it's really an empty and not a failure of
577      // semantic analysis.
578      for (RecordDecl::field_iterator Field = SD->field_begin(),
579                                   FieldEnd = SD->field_end();
580           Field != FieldEnd; ++Field)
581        assert(Field->isUnnamedBitfield() && "Only unnamed bitfields allowed");
582#endif
583      return;
584    }
585
586    // FIXME: volatility
587    FieldDecl *Field = E->getInitializedFieldInUnion();
588    LValue FieldLoc = CGF.EmitLValueForField(DestPtr, Field, true, 0);
589
590    if (NumInitElements) {
591      // Store the initializer into the field
592      EmitInitializationToLValue(E->getInit(0), FieldLoc);
593    } else {
594      // Default-initialize to null
595      EmitNullInitializationToLValue(FieldLoc, Field->getType());
596    }
597
598    return;
599  }
600
601  // Here we iterate over the fields; this makes it simpler to both
602  // default-initialize fields and skip over unnamed fields.
603  for (RecordDecl::field_iterator Field = SD->field_begin(),
604                               FieldEnd = SD->field_end();
605       Field != FieldEnd; ++Field) {
606    // We're done once we hit the flexible array member
607    if (Field->getType()->isIncompleteArrayType())
608      break;
609
610    if (Field->isUnnamedBitfield())
611      continue;
612
613    // FIXME: volatility
614    LValue FieldLoc = CGF.EmitLValueForField(DestPtr, *Field, false, 0);
615    // We never generate write-barries for initialized fields.
616    LValue::SetObjCNonGC(FieldLoc, true);
617    if (CurInitVal < NumInitElements) {
618      // Store the initializer into the field
619      EmitInitializationToLValue(E->getInit(CurInitVal++), FieldLoc);
620    } else {
621      // We're out of initalizers; default-initialize to null
622      EmitNullInitializationToLValue(FieldLoc, Field->getType());
623    }
624  }
625}
626
627//===----------------------------------------------------------------------===//
628//                        Entry Points into this File
629//===----------------------------------------------------------------------===//
630
631/// EmitAggExpr - Emit the computation of the specified expression of aggregate
632/// type.  The result is computed into DestPtr.  Note that if DestPtr is null,
633/// the value of the aggregate expression is not needed.  If VolatileDest is
634/// true, DestPtr cannot be 0.
635void CodeGenFunction::EmitAggExpr(const Expr *E, llvm::Value *DestPtr,
636                                  bool VolatileDest, bool IgnoreResult,
637                                  bool IsInitializer,
638                                  bool RequiresGCollection) {
639  assert(E && hasAggregateLLVMType(E->getType()) &&
640         "Invalid aggregate expression to emit");
641  assert ((DestPtr != 0 || VolatileDest == false)
642          && "volatile aggregate can't be 0");
643
644  AggExprEmitter(*this, DestPtr, VolatileDest, IgnoreResult, IsInitializer,
645                 RequiresGCollection)
646    .Visit(const_cast<Expr*>(E));
647}
648
649void CodeGenFunction::EmitAggregateClear(llvm::Value *DestPtr, QualType Ty) {
650  assert(!Ty->isAnyComplexType() && "Shouldn't happen for complex");
651
652  EmitMemSetToZero(DestPtr, Ty);
653}
654
655void CodeGenFunction::EmitAggregateCopy(llvm::Value *DestPtr,
656                                        llvm::Value *SrcPtr, QualType Ty,
657                                        bool isVolatile) {
658  assert(!Ty->isAnyComplexType() && "Shouldn't happen for complex");
659
660  // Aggregate assignment turns into llvm.memcpy.  This is almost valid per
661  // C99 6.5.16.1p3, which states "If the value being stored in an object is
662  // read from another object that overlaps in anyway the storage of the first
663  // object, then the overlap shall be exact and the two objects shall have
664  // qualified or unqualified versions of a compatible type."
665  //
666  // memcpy is not defined if the source and destination pointers are exactly
667  // equal, but other compilers do this optimization, and almost every memcpy
668  // implementation handles this case safely.  If there is a libc that does not
669  // safely handle this, we can add a target hook.
670  const llvm::Type *BP = llvm::Type::getInt8PtrTy(VMContext);
671  if (DestPtr->getType() != BP)
672    DestPtr = Builder.CreateBitCast(DestPtr, BP, "tmp");
673  if (SrcPtr->getType() != BP)
674    SrcPtr = Builder.CreateBitCast(SrcPtr, BP, "tmp");
675
676  // Get size and alignment info for this aggregate.
677  std::pair<uint64_t, unsigned> TypeInfo = getContext().getTypeInfo(Ty);
678
679  // FIXME: Handle variable sized types.
680  const llvm::Type *IntPtr =
681          llvm::IntegerType::get(VMContext, LLVMPointerWidth);
682
683  // FIXME: If we have a volatile struct, the optimizer can remove what might
684  // appear to be `extra' memory ops:
685  //
686  // volatile struct { int i; } a, b;
687  //
688  // int main() {
689  //   a = b;
690  //   a = b;
691  // }
692  //
693  // we need to use a differnt call here.  We use isVolatile to indicate when
694  // either the source or the destination is volatile.
695  Builder.CreateCall4(CGM.getMemCpyFn(),
696                      DestPtr, SrcPtr,
697                      // TypeInfo.first describes size in bits.
698                      llvm::ConstantInt::get(IntPtr, TypeInfo.first/8),
699                      llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext),
700                                             TypeInfo.second/8));
701}
702