CGExprAgg.cpp revision 2710c4159ff4761ba9867aca18f60a178b297686 
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/Support/Compiler.h"
24#include "llvm/Intrinsics.h"
25using namespace clang;
26using namespace CodeGen;
27
28//===----------------------------------------------------------------------===//
29//                        Aggregate Expression Emitter
30//===----------------------------------------------------------------------===//
31
32namespace  {
33class VISIBILITY_HIDDEN AggExprEmitter : public StmtVisitor<AggExprEmitter> {
34  CodeGenFunction &CGF;
35  CGBuilderTy &Builder;
36  llvm::Value *DestPtr;
37  bool VolatileDest;
38  bool IgnoreResult;
39  bool IsInitializer;
40  bool RequiresGCollection;
41public:
42  AggExprEmitter(CodeGenFunction &cgf, llvm::Value *destPtr, bool v,
43                 bool ignore, bool isinit, bool requiresGCollection)
44    : CGF(cgf), Builder(CGF.Builder),
45      DestPtr(destPtr), VolatileDest(v), IgnoreResult(ignore),
46      IsInitializer(isinit), RequiresGCollection(requiresGCollection) {
47  }
48
49  //===--------------------------------------------------------------------===//
50  //                               Utilities
51  //===--------------------------------------------------------------------===//
52
53  /// EmitAggLoadOfLValue - Given an expression with aggregate type that
54  /// represents a value lvalue, this method emits the address of the lvalue,
55  /// then loads the result into DestPtr.
56  void EmitAggLoadOfLValue(const Expr *E);
57
58  /// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired.
59  void EmitFinalDestCopy(const Expr *E, LValue Src, bool Ignore = false);
60  void EmitFinalDestCopy(const Expr *E, RValue Src, bool Ignore = false);
61
62  //===--------------------------------------------------------------------===//
63  //                            Visitor Methods
64  //===--------------------------------------------------------------------===//
65
66  void VisitStmt(Stmt *S) {
67    CGF.ErrorUnsupported(S, "aggregate expression");
68  }
69  void VisitParenExpr(ParenExpr *PE) { Visit(PE->getSubExpr()); }
70  void VisitUnaryExtension(UnaryOperator *E) { Visit(E->getSubExpr()); }
71
72  // l-values.
73  void VisitDeclRefExpr(DeclRefExpr *DRE) { EmitAggLoadOfLValue(DRE); }
74  void VisitMemberExpr(MemberExpr *ME) { EmitAggLoadOfLValue(ME); }
75  void VisitUnaryDeref(UnaryOperator *E) { EmitAggLoadOfLValue(E); }
76  void VisitStringLiteral(StringLiteral *E) { EmitAggLoadOfLValue(E); }
77  void VisitCompoundLiteralExpr(CompoundLiteralExpr *E) {
78    EmitAggLoadOfLValue(E);
79  }
80  void VisitArraySubscriptExpr(ArraySubscriptExpr *E) {
81    EmitAggLoadOfLValue(E);
82  }
83  void VisitBlockDeclRefExpr(const BlockDeclRefExpr *E) {
84    EmitAggLoadOfLValue(E);
85  }
86  void VisitPredefinedExpr(const PredefinedExpr *E) {
87    EmitAggLoadOfLValue(E);
88  }
89
90  // Operators.
91  void VisitCastExpr(CastExpr *E);
92  void VisitCallExpr(const CallExpr *E);
93  void VisitStmtExpr(const StmtExpr *E);
94  void VisitBinaryOperator(const BinaryOperator *BO);
95  void VisitPointerToDataMemberBinaryOperator(const BinaryOperator *BO);
96  void VisitBinAssign(const BinaryOperator *E);
97  void VisitBinComma(const BinaryOperator *E);
98  void VisitUnaryAddrOf(const UnaryOperator *E);
99
100  void VisitObjCMessageExpr(ObjCMessageExpr *E);
101  void VisitObjCIvarRefExpr(ObjCIvarRefExpr *E) {
102    EmitAggLoadOfLValue(E);
103  }
104  void VisitObjCPropertyRefExpr(ObjCPropertyRefExpr *E);
105  void VisitObjCImplicitSetterGetterRefExpr(ObjCImplicitSetterGetterRefExpr *E);
106
107  void VisitConditionalOperator(const ConditionalOperator *CO);
108  void VisitChooseExpr(const ChooseExpr *CE);
109  void VisitInitListExpr(InitListExpr *E);
110  void VisitCXXDefaultArgExpr(CXXDefaultArgExpr *DAE) {
111    Visit(DAE->getExpr());
112  }
113  void VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E);
114  void VisitCXXConstructExpr(const CXXConstructExpr *E);
115  void VisitCXXExprWithTemporaries(CXXExprWithTemporaries *E);
116  void VisitCXXZeroInitValueExpr(CXXZeroInitValueExpr *E);
117  void VisitCXXTypeidExpr(CXXTypeidExpr *E) { EmitAggLoadOfLValue(E); }
118
119  void VisitVAArgExpr(VAArgExpr *E);
120
121  void EmitInitializationToLValue(Expr *E, LValue Address);
122  void EmitNullInitializationToLValue(LValue Address, QualType T);
123  //  case Expr::ChooseExprClass:
124
125};
126}  // end anonymous namespace.
127
128//===----------------------------------------------------------------------===//
129//                                Utilities
130//===----------------------------------------------------------------------===//
131
132/// EmitAggLoadOfLValue - Given an expression with aggregate type that
133/// represents a value lvalue, this method emits the address of the lvalue,
134/// then loads the result into DestPtr.
135void AggExprEmitter::EmitAggLoadOfLValue(const Expr *E) {
136  LValue LV = CGF.EmitLValue(E);
137  EmitFinalDestCopy(E, LV);
138}
139
140/// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired.
141void AggExprEmitter::EmitFinalDestCopy(const Expr *E, RValue Src, bool Ignore) {
142  assert(Src.isAggregate() && "value must be aggregate value!");
143
144  // If the result is ignored, don't copy from the value.
145  if (DestPtr == 0) {
146    if (!Src.isVolatileQualified() || (IgnoreResult && Ignore))
147      return;
148    // If the source is volatile, we must read from it; to do that, we need
149    // some place to put it.
150    DestPtr = CGF.CreateTempAlloca(CGF.ConvertType(E->getType()), "agg.tmp");
151  }
152
153  if (RequiresGCollection) {
154    CGF.CGM.getObjCRuntime().EmitGCMemmoveCollectable(CGF,
155                                              DestPtr, Src.getAggregateAddr(),
156                                              E->getType());
157    return;
158  }
159  // If the result of the assignment is used, copy the LHS there also.
160  // FIXME: Pass VolatileDest as well.  I think we also need to merge volatile
161  // from the source as well, as we can't eliminate it if either operand
162  // is volatile, unless copy has volatile for both source and destination..
163  CGF.EmitAggregateCopy(DestPtr, Src.getAggregateAddr(), E->getType(),
164                        VolatileDest|Src.isVolatileQualified());
165}
166
167/// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired.
168void AggExprEmitter::EmitFinalDestCopy(const Expr *E, LValue Src, bool Ignore) {
169  assert(Src.isSimple() && "Can't have aggregate bitfield, vector, etc");
170
171  EmitFinalDestCopy(E, RValue::getAggregate(Src.getAddress(),
172                                            Src.isVolatileQualified()),
173                    Ignore);
174}
175
176//===----------------------------------------------------------------------===//
177//                            Visitor Methods
178//===----------------------------------------------------------------------===//
179
180void AggExprEmitter::VisitCastExpr(CastExpr *E) {
181  switch (E->getCastKind()) {
182  default: assert(0 && "Unhandled cast kind!");
183
184  case CastExpr::CK_ToUnion: {
185    // GCC union extension
186    QualType PtrTy =
187    CGF.getContext().getPointerType(E->getSubExpr()->getType());
188    llvm::Value *CastPtr = Builder.CreateBitCast(DestPtr,
189                                                 CGF.ConvertType(PtrTy));
190    EmitInitializationToLValue(E->getSubExpr(),
191                               LValue::MakeAddr(CastPtr, Qualifiers()));
192    break;
193  }
194
195  // FIXME: Remove the CK_Unknown check here.
196  case CastExpr::CK_Unknown:
197  case CastExpr::CK_NoOp:
198  case CastExpr::CK_UserDefinedConversion:
199  case CastExpr::CK_ConstructorConversion:
200    assert(CGF.getContext().hasSameUnqualifiedType(E->getSubExpr()->getType(),
201                                                   E->getType()) &&
202           "Implicit cast types must be compatible");
203    Visit(E->getSubExpr());
204    break;
205
206  case CastExpr::CK_NullToMemberPointer: {
207    const llvm::Type *PtrDiffTy =
208      CGF.ConvertType(CGF.getContext().getPointerDiffType());
209
210    llvm::Value *NullValue = llvm::Constant::getNullValue(PtrDiffTy);
211    llvm::Value *Ptr = Builder.CreateStructGEP(DestPtr, 0, "ptr");
212    Builder.CreateStore(NullValue, Ptr, VolatileDest);
213
214    llvm::Value *Adj = Builder.CreateStructGEP(DestPtr, 1, "adj");
215    Builder.CreateStore(NullValue, Adj, VolatileDest);
216
217    break;
218  }
219
220  case CastExpr::CK_BitCast: {
221    // This must be a member function pointer cast.
222    Visit(E->getSubExpr());
223    break;
224  }
225
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 *SrcDecl =
246      cast<CXXRecordDecl>(SrcType->getAs<MemberPointerType>()->
247                          getClass()->getAs<RecordType>()->getDecl());
248    const CXXRecordDecl *DstDecl =
249      cast<CXXRecordDecl>(E->getType()->getAs<MemberPointerType>()->
250                          getClass()->getAs<RecordType>()->getDecl());
251
252    llvm::Constant *Adj = CGF.CGM.GetCXXBaseClassOffset(DstDecl, SrcDecl);
253    if (Adj)
254      SrcAdj = Builder.CreateAdd(SrcAdj, Adj, "adj");
255
256    Builder.CreateStore(SrcAdj, DstAdj, VolatileDest);
257    break;
258  }
259  }
260}
261
262void AggExprEmitter::VisitCallExpr(const CallExpr *E) {
263  if (E->getCallReturnType()->isReferenceType()) {
264    EmitAggLoadOfLValue(E);
265    return;
266  }
267
268  RValue RV = CGF.EmitCallExpr(E);
269  EmitFinalDestCopy(E, RV);
270}
271
272void AggExprEmitter::VisitObjCMessageExpr(ObjCMessageExpr *E) {
273  RValue RV = CGF.EmitObjCMessageExpr(E);
274  EmitFinalDestCopy(E, RV);
275}
276
277void AggExprEmitter::VisitObjCPropertyRefExpr(ObjCPropertyRefExpr *E) {
278  RValue RV = CGF.EmitObjCPropertyGet(E);
279  EmitFinalDestCopy(E, RV);
280}
281
282void AggExprEmitter::VisitObjCImplicitSetterGetterRefExpr(
283                                   ObjCImplicitSetterGetterRefExpr *E) {
284  RValue RV = CGF.EmitObjCPropertyGet(E);
285  EmitFinalDestCopy(E, RV);
286}
287
288void AggExprEmitter::VisitBinComma(const BinaryOperator *E) {
289  CGF.EmitAnyExpr(E->getLHS(), 0, false, true);
290  CGF.EmitAggExpr(E->getRHS(), DestPtr, VolatileDest,
291                  /*IgnoreResult=*/false, IsInitializer);
292}
293
294void AggExprEmitter::VisitUnaryAddrOf(const UnaryOperator *E) {
295  // We have a member function pointer.
296  const MemberPointerType *MPT = E->getType()->getAs<MemberPointerType>();
297  (void) MPT;
298  assert(MPT->getPointeeType()->isFunctionProtoType() &&
299         "Unexpected member pointer type!");
300
301  const DeclRefExpr *DRE = cast<DeclRefExpr>(E->getSubExpr());
302  const CXXMethodDecl *MD = cast<CXXMethodDecl>(DRE->getDecl());
303
304  const llvm::Type *PtrDiffTy =
305    CGF.ConvertType(CGF.getContext().getPointerDiffType());
306
307  llvm::Value *DstPtr = Builder.CreateStructGEP(DestPtr, 0, "dst.ptr");
308  llvm::Value *FuncPtr;
309
310  if (MD->isVirtual()) {
311    int64_t Index =
312      CGF.CGM.getVtableInfo().getMethodVtableIndex(MD);
313
314    FuncPtr = llvm::ConstantInt::get(PtrDiffTy, Index + 1);
315  } else {
316    FuncPtr = llvm::ConstantExpr::getPtrToInt(CGF.CGM.GetAddrOfFunction(MD),
317                                              PtrDiffTy);
318  }
319  Builder.CreateStore(FuncPtr, DstPtr, VolatileDest);
320
321  llvm::Value *AdjPtr = Builder.CreateStructGEP(DestPtr, 1, "dst.adj");
322
323  // The adjustment will always be 0.
324  Builder.CreateStore(llvm::ConstantInt::get(PtrDiffTy, 0), AdjPtr,
325                      VolatileDest);
326}
327
328void AggExprEmitter::VisitStmtExpr(const StmtExpr *E) {
329  CGF.EmitCompoundStmt(*E->getSubStmt(), true, DestPtr, VolatileDest);
330}
331
332void AggExprEmitter::VisitBinaryOperator(const BinaryOperator *E) {
333  if (E->getOpcode() == BinaryOperator::PtrMemD ||
334      E->getOpcode() == BinaryOperator::PtrMemI)
335    VisitPointerToDataMemberBinaryOperator(E);
336  else
337    CGF.ErrorUnsupported(E, "aggregate binary expression");
338}
339
340void AggExprEmitter::VisitPointerToDataMemberBinaryOperator(
341                                                    const BinaryOperator *E) {
342  LValue LV = CGF.EmitPointerToDataMemberBinaryExpr(E);
343  EmitFinalDestCopy(E, LV);
344}
345
346void AggExprEmitter::VisitBinAssign(const BinaryOperator *E) {
347  // For an assignment to work, the value on the right has
348  // to be compatible with the value on the left.
349  assert(CGF.getContext().hasSameUnqualifiedType(E->getLHS()->getType(),
350                                                 E->getRHS()->getType())
351         && "Invalid assignment");
352  LValue LHS = CGF.EmitLValue(E->getLHS());
353
354  // We have to special case property setters, otherwise we must have
355  // a simple lvalue (no aggregates inside vectors, bitfields).
356  if (LHS.isPropertyRef()) {
357    llvm::Value *AggLoc = DestPtr;
358    if (!AggLoc)
359      AggLoc = CGF.CreateTempAlloca(CGF.ConvertType(E->getRHS()->getType()));
360    CGF.EmitAggExpr(E->getRHS(), AggLoc, VolatileDest);
361    CGF.EmitObjCPropertySet(LHS.getPropertyRefExpr(),
362                            RValue::getAggregate(AggLoc, VolatileDest));
363  } else if (LHS.isKVCRef()) {
364    llvm::Value *AggLoc = DestPtr;
365    if (!AggLoc)
366      AggLoc = CGF.CreateTempAlloca(CGF.ConvertType(E->getRHS()->getType()));
367    CGF.EmitAggExpr(E->getRHS(), AggLoc, VolatileDest);
368    CGF.EmitObjCPropertySet(LHS.getKVCRefExpr(),
369                            RValue::getAggregate(AggLoc, VolatileDest));
370  } else {
371    bool RequiresGCollection = false;
372    if (CGF.getContext().getLangOptions().NeXTRuntime) {
373      QualType LHSTy = E->getLHS()->getType();
374      if (const RecordType *FDTTy = LHSTy.getTypePtr()->getAs<RecordType>())
375        RequiresGCollection = FDTTy->getDecl()->hasObjectMember();
376    }
377    // Codegen the RHS so that it stores directly into the LHS.
378    CGF.EmitAggExpr(E->getRHS(), LHS.getAddress(), LHS.isVolatileQualified(),
379                    false, false, RequiresGCollection);
380    EmitFinalDestCopy(E, LHS, true);
381  }
382}
383
384void AggExprEmitter::VisitConditionalOperator(const ConditionalOperator *E) {
385  llvm::BasicBlock *LHSBlock = CGF.createBasicBlock("cond.true");
386  llvm::BasicBlock *RHSBlock = CGF.createBasicBlock("cond.false");
387  llvm::BasicBlock *ContBlock = CGF.createBasicBlock("cond.end");
388
389  llvm::Value *Cond = CGF.EvaluateExprAsBool(E->getCond());
390  Builder.CreateCondBr(Cond, LHSBlock, RHSBlock);
391
392  CGF.PushConditionalTempDestruction();
393  CGF.EmitBlock(LHSBlock);
394
395  // Handle the GNU extension for missing LHS.
396  assert(E->getLHS() && "Must have LHS for aggregate value");
397
398  Visit(E->getLHS());
399  CGF.PopConditionalTempDestruction();
400  CGF.EmitBranch(ContBlock);
401
402  CGF.PushConditionalTempDestruction();
403  CGF.EmitBlock(RHSBlock);
404
405  Visit(E->getRHS());
406  CGF.PopConditionalTempDestruction();
407  CGF.EmitBranch(ContBlock);
408
409  CGF.EmitBlock(ContBlock);
410}
411
412void AggExprEmitter::VisitChooseExpr(const ChooseExpr *CE) {
413  Visit(CE->getChosenSubExpr(CGF.getContext()));
414}
415
416void AggExprEmitter::VisitVAArgExpr(VAArgExpr *VE) {
417  llvm::Value *ArgValue = CGF.EmitVAListRef(VE->getSubExpr());
418  llvm::Value *ArgPtr = CGF.EmitVAArg(ArgValue, VE->getType());
419
420  if (!ArgPtr) {
421    CGF.ErrorUnsupported(VE, "aggregate va_arg expression");
422    return;
423  }
424
425  EmitFinalDestCopy(VE, LValue::MakeAddr(ArgPtr, Qualifiers()));
426}
427
428void AggExprEmitter::VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E) {
429  llvm::Value *Val = DestPtr;
430
431  if (!Val) {
432    // Create a temporary variable.
433    Val = CGF.CreateTempAlloca(CGF.ConvertTypeForMem(E->getType()), "tmp");
434
435    // FIXME: volatile
436    CGF.EmitAggExpr(E->getSubExpr(), Val, false);
437  } else
438    Visit(E->getSubExpr());
439
440  // Don't make this a live temporary if we're emitting an initializer expr.
441  if (!IsInitializer)
442    CGF.PushCXXTemporary(E->getTemporary(), Val);
443}
444
445void
446AggExprEmitter::VisitCXXConstructExpr(const CXXConstructExpr *E) {
447  llvm::Value *Val = DestPtr;
448
449  if (!Val) {
450    // Create a temporary variable.
451    Val = CGF.CreateTempAlloca(CGF.ConvertTypeForMem(E->getType()), "tmp");
452  }
453
454  CGF.EmitCXXConstructExpr(Val, E);
455}
456
457void AggExprEmitter::VisitCXXExprWithTemporaries(CXXExprWithTemporaries *E) {
458  CGF.EmitCXXExprWithTemporaries(E, DestPtr, VolatileDest, IsInitializer);
459}
460
461void AggExprEmitter::VisitCXXZeroInitValueExpr(CXXZeroInitValueExpr *E) {
462  LValue lvalue = LValue::MakeAddr(DestPtr, Qualifiers());
463  EmitNullInitializationToLValue(lvalue, E->getType());
464}
465
466void AggExprEmitter::EmitInitializationToLValue(Expr* E, LValue LV) {
467  // FIXME: Ignore result?
468  // FIXME: Are initializers affected by volatile?
469  if (isa<ImplicitValueInitExpr>(E)) {
470    EmitNullInitializationToLValue(LV, E->getType());
471  } else if (E->getType()->isComplexType()) {
472    CGF.EmitComplexExprIntoAddr(E, LV.getAddress(), false);
473  } else if (CGF.hasAggregateLLVMType(E->getType())) {
474    CGF.EmitAnyExpr(E, LV.getAddress(), false);
475  } else {
476    CGF.EmitStoreThroughLValue(CGF.EmitAnyExpr(E), LV, E->getType());
477  }
478}
479
480void AggExprEmitter::EmitNullInitializationToLValue(LValue LV, QualType T) {
481  if (!CGF.hasAggregateLLVMType(T)) {
482    // For non-aggregates, we can store zero
483    llvm::Value *Null = llvm::Constant::getNullValue(CGF.ConvertType(T));
484    CGF.EmitStoreThroughLValue(RValue::get(Null), LV, T);
485  } else {
486    // Otherwise, just memset the whole thing to zero.  This is legal
487    // because in LLVM, all default initializers are guaranteed to have a
488    // bit pattern of all zeros.
489    // FIXME: That isn't true for member pointers!
490    // There's a potential optimization opportunity in combining
491    // memsets; that would be easy for arrays, but relatively
492    // difficult for structures with the current code.
493    CGF.EmitMemSetToZero(LV.getAddress(), T);
494  }
495}
496
497void AggExprEmitter::VisitInitListExpr(InitListExpr *E) {
498#if 0
499  // FIXME: Disabled while we figure out what to do about
500  // test/CodeGen/bitfield.c
501  //
502  // If we can, prefer a copy from a global; this is a lot less code for long
503  // globals, and it's easier for the current optimizers to analyze.
504  // FIXME: Should we really be doing this? Should we try to avoid cases where
505  // we emit a global with a lot of zeros?  Should we try to avoid short
506  // globals?
507  if (E->isConstantInitializer(CGF.getContext(), 0)) {
508    llvm::Constant* C = CGF.CGM.EmitConstantExpr(E, &CGF);
509    llvm::GlobalVariable* GV =
510    new llvm::GlobalVariable(C->getType(), true,
511                             llvm::GlobalValue::InternalLinkage,
512                             C, "", &CGF.CGM.getModule(), 0);
513    EmitFinalDestCopy(E, LValue::MakeAddr(GV, 0));
514    return;
515  }
516#endif
517  if (E->hadArrayRangeDesignator()) {
518    CGF.ErrorUnsupported(E, "GNU array range designator extension");
519  }
520
521  // Handle initialization of an array.
522  if (E->getType()->isArrayType()) {
523    const llvm::PointerType *APType =
524      cast<llvm::PointerType>(DestPtr->getType());
525    const llvm::ArrayType *AType =
526      cast<llvm::ArrayType>(APType->getElementType());
527
528    uint64_t NumInitElements = E->getNumInits();
529
530    if (E->getNumInits() > 0) {
531      QualType T1 = E->getType();
532      QualType T2 = E->getInit(0)->getType();
533      if (CGF.getContext().hasSameUnqualifiedType(T1, T2)) {
534        EmitAggLoadOfLValue(E->getInit(0));
535        return;
536      }
537    }
538
539    uint64_t NumArrayElements = AType->getNumElements();
540    QualType ElementType = CGF.getContext().getCanonicalType(E->getType());
541    ElementType = CGF.getContext().getAsArrayType(ElementType)->getElementType();
542
543    // FIXME: were we intentionally ignoring address spaces and GC attributes?
544    Qualifiers Quals = CGF.MakeQualifiers(ElementType);
545
546    for (uint64_t i = 0; i != NumArrayElements; ++i) {
547      llvm::Value *NextVal = Builder.CreateStructGEP(DestPtr, i, ".array");
548      if (i < NumInitElements)
549        EmitInitializationToLValue(E->getInit(i),
550                                   LValue::MakeAddr(NextVal, Quals));
551      else
552        EmitNullInitializationToLValue(LValue::MakeAddr(NextVal, Quals),
553                                       ElementType);
554    }
555    return;
556  }
557
558  assert(E->getType()->isRecordType() && "Only support structs/unions here!");
559
560  // Do struct initialization; this code just sets each individual member
561  // to the approprate value.  This makes bitfield support automatic;
562  // the disadvantage is that the generated code is more difficult for
563  // the optimizer, especially with bitfields.
564  unsigned NumInitElements = E->getNumInits();
565  RecordDecl *SD = E->getType()->getAs<RecordType>()->getDecl();
566  unsigned CurInitVal = 0;
567
568  if (E->getType()->isUnionType()) {
569    // Only initialize one field of a union. The field itself is
570    // specified by the initializer list.
571    if (!E->getInitializedFieldInUnion()) {
572      // Empty union; we have nothing to do.
573
574#ifndef NDEBUG
575      // Make sure that it's really an empty and not a failure of
576      // semantic analysis.
577      for (RecordDecl::field_iterator Field = SD->field_begin(),
578                                   FieldEnd = SD->field_end();
579           Field != FieldEnd; ++Field)
580        assert(Field->isUnnamedBitfield() && "Only unnamed bitfields allowed");
581#endif
582      return;
583    }
584
585    // FIXME: volatility
586    FieldDecl *Field = E->getInitializedFieldInUnion();
587    LValue FieldLoc = CGF.EmitLValueForField(DestPtr, Field, true, 0);
588
589    if (NumInitElements) {
590      // Store the initializer into the field
591      EmitInitializationToLValue(E->getInit(0), FieldLoc);
592    } else {
593      // Default-initialize to null
594      EmitNullInitializationToLValue(FieldLoc, Field->getType());
595    }
596
597    return;
598  }
599
600  // Here we iterate over the fields; this makes it simpler to both
601  // default-initialize fields and skip over unnamed fields.
602  for (RecordDecl::field_iterator Field = SD->field_begin(),
603                               FieldEnd = SD->field_end();
604       Field != FieldEnd; ++Field) {
605    // We're done once we hit the flexible array member
606    if (Field->getType()->isIncompleteArrayType())
607      break;
608
609    if (Field->isUnnamedBitfield())
610      continue;
611
612    // FIXME: volatility
613    LValue FieldLoc = CGF.EmitLValueForField(DestPtr, *Field, false, 0);
614    // We never generate write-barries for initialized fields.
615    LValue::SetObjCNonGC(FieldLoc, true);
616    if (CurInitVal < NumInitElements) {
617      // Store the initializer into the field
618      EmitInitializationToLValue(E->getInit(CurInitVal++), FieldLoc);
619    } else {
620      // We're out of initalizers; default-initialize to null
621      EmitNullInitializationToLValue(FieldLoc, Field->getType());
622    }
623  }
624}
625
626//===----------------------------------------------------------------------===//
627//                        Entry Points into this File
628//===----------------------------------------------------------------------===//
629
630/// EmitAggExpr - Emit the computation of the specified expression of aggregate
631/// type.  The result is computed into DestPtr.  Note that if DestPtr is null,
632/// the value of the aggregate expression is not needed.  If VolatileDest is
633/// true, DestPtr cannot be 0.
634void CodeGenFunction::EmitAggExpr(const Expr *E, llvm::Value *DestPtr,
635                                  bool VolatileDest, bool IgnoreResult,
636                                  bool IsInitializer,
637                                  bool RequiresGCollection) {
638  assert(E && hasAggregateLLVMType(E->getType()) &&
639         "Invalid aggregate expression to emit");
640  assert ((DestPtr != 0 || VolatileDest == false)
641          && "volatile aggregate can't be 0");
642
643  AggExprEmitter(*this, DestPtr, VolatileDest, IgnoreResult, IsInitializer,
644                 RequiresGCollection)
645    .Visit(const_cast<Expr*>(E));
646}
647
648void CodeGenFunction::EmitAggregateClear(llvm::Value *DestPtr, QualType Ty) {
649  assert(!Ty->isAnyComplexType() && "Shouldn't happen for complex");
650
651  EmitMemSetToZero(DestPtr, Ty);
652}
653
654void CodeGenFunction::EmitAggregateCopy(llvm::Value *DestPtr,
655                                        llvm::Value *SrcPtr, QualType Ty,
656                                        bool isVolatile) {
657  assert(!Ty->isAnyComplexType() && "Shouldn't happen for complex");
658
659  // Aggregate assignment turns into llvm.memcpy.  This is almost valid per
660  // C99 6.5.16.1p3, which states "If the value being stored in an object is
661  // read from another object that overlaps in anyway the storage of the first
662  // object, then the overlap shall be exact and the two objects shall have
663  // qualified or unqualified versions of a compatible type."
664  //
665  // memcpy is not defined if the source and destination pointers are exactly
666  // equal, but other compilers do this optimization, and almost every memcpy
667  // implementation handles this case safely.  If there is a libc that does not
668  // safely handle this, we can add a target hook.
669  const llvm::Type *BP = llvm::Type::getInt8PtrTy(VMContext);
670  if (DestPtr->getType() != BP)
671    DestPtr = Builder.CreateBitCast(DestPtr, BP, "tmp");
672  if (SrcPtr->getType() != BP)
673    SrcPtr = Builder.CreateBitCast(SrcPtr, BP, "tmp");
674
675  // Get size and alignment info for this aggregate.
676  std::pair<uint64_t, unsigned> TypeInfo = getContext().getTypeInfo(Ty);
677
678  // FIXME: Handle variable sized types.
679  const llvm::Type *IntPtr =
680          llvm::IntegerType::get(VMContext, LLVMPointerWidth);
681
682  // FIXME: If we have a volatile struct, the optimizer can remove what might
683  // appear to be `extra' memory ops:
684  //
685  // volatile struct { int i; } a, b;
686  //
687  // int main() {
688  //   a = b;
689  //   a = b;
690  // }
691  //
692  // we need to use a differnt call here.  We use isVolatile to indicate when
693  // either the source or the destination is volatile.
694  Builder.CreateCall4(CGM.getMemCpyFn(),
695                      DestPtr, SrcPtr,
696                      // TypeInfo.first describes size in bits.
697                      llvm::ConstantInt::get(IntPtr, TypeInfo.first/8),
698                      llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext),
699                                             TypeInfo.second/8));
700}
701