CGExprAgg.cpp revision ef072fd2f3347cfd857d6eb787b245b950771430 
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;
40
41  ReturnValueSlot getReturnValueSlot() const {
42    return ReturnValueSlot(DestPtr, VolatileDest);
43  }
44public:
45  AggExprEmitter(CodeGenFunction &cgf, llvm::Value *destPtr, bool v,
46                 bool ignore, bool isinit, bool requiresGCollection)
47    : CGF(cgf), Builder(CGF.Builder),
48      DestPtr(destPtr), VolatileDest(v), IgnoreResult(ignore),
49      IsInitializer(isinit), RequiresGCollection(requiresGCollection) {
50  }
51
52  //===--------------------------------------------------------------------===//
53  //                               Utilities
54  //===--------------------------------------------------------------------===//
55
56  /// EmitAggLoadOfLValue - Given an expression with aggregate type that
57  /// represents a value lvalue, this method emits the address of the lvalue,
58  /// then loads the result into DestPtr.
59  void EmitAggLoadOfLValue(const Expr *E);
60
61  /// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired.
62  void EmitFinalDestCopy(const Expr *E, LValue Src, bool Ignore = false);
63  void EmitFinalDestCopy(const Expr *E, RValue Src, bool Ignore = false);
64
65  //===--------------------------------------------------------------------===//
66  //                            Visitor Methods
67  //===--------------------------------------------------------------------===//
68
69  void VisitStmt(Stmt *S) {
70    CGF.ErrorUnsupported(S, "aggregate expression");
71  }
72  void VisitParenExpr(ParenExpr *PE) { Visit(PE->getSubExpr()); }
73  void VisitUnaryExtension(UnaryOperator *E) { Visit(E->getSubExpr()); }
74
75  // l-values.
76  void VisitDeclRefExpr(DeclRefExpr *DRE) { EmitAggLoadOfLValue(DRE); }
77  void VisitMemberExpr(MemberExpr *ME) { EmitAggLoadOfLValue(ME); }
78  void VisitUnaryDeref(UnaryOperator *E) { EmitAggLoadOfLValue(E); }
79  void VisitStringLiteral(StringLiteral *E) { EmitAggLoadOfLValue(E); }
80  void VisitCompoundLiteralExpr(CompoundLiteralExpr *E) {
81    EmitAggLoadOfLValue(E);
82  }
83  void VisitArraySubscriptExpr(ArraySubscriptExpr *E) {
84    EmitAggLoadOfLValue(E);
85  }
86  void VisitBlockDeclRefExpr(const BlockDeclRefExpr *E) {
87    EmitAggLoadOfLValue(E);
88  }
89  void VisitPredefinedExpr(const PredefinedExpr *E) {
90    EmitAggLoadOfLValue(E);
91  }
92
93  // Operators.
94  void VisitCastExpr(CastExpr *E);
95  void VisitCallExpr(const CallExpr *E);
96  void VisitStmtExpr(const StmtExpr *E);
97  void VisitBinaryOperator(const BinaryOperator *BO);
98  void VisitPointerToDataMemberBinaryOperator(const BinaryOperator *BO);
99  void VisitBinAssign(const BinaryOperator *E);
100  void VisitBinComma(const BinaryOperator *E);
101  void VisitUnaryAddrOf(const UnaryOperator *E);
102
103  void VisitObjCMessageExpr(ObjCMessageExpr *E);
104  void VisitObjCIvarRefExpr(ObjCIvarRefExpr *E) {
105    EmitAggLoadOfLValue(E);
106  }
107  void VisitObjCPropertyRefExpr(ObjCPropertyRefExpr *E);
108  void VisitObjCImplicitSetterGetterRefExpr(ObjCImplicitSetterGetterRefExpr *E);
109
110  void VisitConditionalOperator(const ConditionalOperator *CO);
111  void VisitChooseExpr(const ChooseExpr *CE);
112  void VisitInitListExpr(InitListExpr *E);
113  void VisitImplicitValueInitExpr(ImplicitValueInitExpr *E);
114  void VisitCXXDefaultArgExpr(CXXDefaultArgExpr *DAE) {
115    Visit(DAE->getExpr());
116  }
117  void VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E);
118  void VisitCXXConstructExpr(const CXXConstructExpr *E);
119  void VisitCXXExprWithTemporaries(CXXExprWithTemporaries *E);
120  void VisitCXXZeroInitValueExpr(CXXZeroInitValueExpr *E);
121  void VisitCXXTypeidExpr(CXXTypeidExpr *E) { EmitAggLoadOfLValue(E); }
122
123  void VisitVAArgExpr(VAArgExpr *E);
124
125  void EmitInitializationToLValue(Expr *E, LValue Address, QualType T);
126  void EmitNullInitializationToLValue(LValue Address, QualType T);
127  //  case Expr::ChooseExprClass:
128  void VisitCXXThrowExpr(const CXXThrowExpr *E) { CGF.EmitCXXThrowExpr(E); }
129};
130}  // end anonymous namespace.
131
132//===----------------------------------------------------------------------===//
133//                                Utilities
134//===----------------------------------------------------------------------===//
135
136/// EmitAggLoadOfLValue - Given an expression with aggregate type that
137/// represents a value lvalue, this method emits the address of the lvalue,
138/// then loads the result into DestPtr.
139void AggExprEmitter::EmitAggLoadOfLValue(const Expr *E) {
140  LValue LV = CGF.EmitLValue(E);
141  EmitFinalDestCopy(E, LV);
142}
143
144/// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired.
145void AggExprEmitter::EmitFinalDestCopy(const Expr *E, RValue Src, bool Ignore) {
146  assert(Src.isAggregate() && "value must be aggregate value!");
147
148  // If the result is ignored, don't copy from the value.
149  if (DestPtr == 0) {
150    if (!Src.isVolatileQualified() || (IgnoreResult && Ignore))
151      return;
152    // If the source is volatile, we must read from it; to do that, we need
153    // some place to put it.
154    DestPtr = CGF.CreateMemTemp(E->getType(), "agg.tmp");
155  }
156
157  if (RequiresGCollection) {
158    CGF.CGM.getObjCRuntime().EmitGCMemmoveCollectable(CGF,
159                                              DestPtr, Src.getAggregateAddr(),
160                                              E->getType());
161    return;
162  }
163  // If the result of the assignment is used, copy the LHS there also.
164  // FIXME: Pass VolatileDest as well.  I think we also need to merge volatile
165  // from the source as well, as we can't eliminate it if either operand
166  // is volatile, unless copy has volatile for both source and destination..
167  CGF.EmitAggregateCopy(DestPtr, Src.getAggregateAddr(), E->getType(),
168                        VolatileDest|Src.isVolatileQualified());
169}
170
171/// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired.
172void AggExprEmitter::EmitFinalDestCopy(const Expr *E, LValue Src, bool Ignore) {
173  assert(Src.isSimple() && "Can't have aggregate bitfield, vector, etc");
174
175  EmitFinalDestCopy(E, RValue::getAggregate(Src.getAddress(),
176                                            Src.isVolatileQualified()),
177                    Ignore);
178}
179
180//===----------------------------------------------------------------------===//
181//                            Visitor Methods
182//===----------------------------------------------------------------------===//
183
184void AggExprEmitter::VisitCastExpr(CastExpr *E) {
185  if (!DestPtr && E->getCastKind() != CastExpr::CK_Dynamic) {
186    Visit(E->getSubExpr());
187    return;
188  }
189
190  switch (E->getCastKind()) {
191  default: assert(0 && "Unhandled cast kind!");
192
193  case CastExpr::CK_Dynamic: {
194    assert(isa<CXXDynamicCastExpr>(E) && "CK_Dynamic without a dynamic_cast?");
195    LValue LV = CGF.EmitCheckedLValue(E->getSubExpr());
196    // FIXME: Do we also need to handle property references here?
197    if (LV.isSimple())
198      CGF.EmitDynamicCast(LV.getAddress(), cast<CXXDynamicCastExpr>(E));
199    else
200      CGF.CGM.ErrorUnsupported(E, "non-simple lvalue dynamic_cast");
201
202    if (DestPtr)
203      CGF.CGM.ErrorUnsupported(E, "lvalue dynamic_cast with a destination");
204    break;
205  }
206
207  case CastExpr::CK_ToUnion: {
208    // GCC union extension
209    QualType PtrTy =
210    CGF.getContext().getPointerType(E->getSubExpr()->getType());
211    llvm::Value *CastPtr = Builder.CreateBitCast(DestPtr,
212                                                 CGF.ConvertType(PtrTy));
213    EmitInitializationToLValue(E->getSubExpr(),
214                               LValue::MakeAddr(CastPtr, Qualifiers()),
215                               E->getSubExpr()->getType());
216    break;
217  }
218
219  // FIXME: Remove the CK_Unknown check here.
220  case CastExpr::CK_Unknown:
221  case CastExpr::CK_NoOp:
222  case CastExpr::CK_UserDefinedConversion:
223  case CastExpr::CK_ConstructorConversion:
224    assert(CGF.getContext().hasSameUnqualifiedType(E->getSubExpr()->getType(),
225                                                   E->getType()) &&
226           "Implicit cast types must be compatible");
227    Visit(E->getSubExpr());
228    break;
229
230  case CastExpr::CK_NullToMemberPointer: {
231    // If the subexpression's type is the C++0x nullptr_t, emit the
232    // subexpression, which may have side effects.
233    if (E->getSubExpr()->getType()->isNullPtrType())
234      Visit(E->getSubExpr());
235
236    const llvm::Type *PtrDiffTy =
237      CGF.ConvertType(CGF.getContext().getPointerDiffType());
238
239    llvm::Value *NullValue = llvm::Constant::getNullValue(PtrDiffTy);
240    llvm::Value *Ptr = Builder.CreateStructGEP(DestPtr, 0, "ptr");
241    Builder.CreateStore(NullValue, Ptr, VolatileDest);
242
243    llvm::Value *Adj = Builder.CreateStructGEP(DestPtr, 1, "adj");
244    Builder.CreateStore(NullValue, Adj, VolatileDest);
245
246    break;
247  }
248
249  case CastExpr::CK_BitCast: {
250    // This must be a member function pointer cast.
251    Visit(E->getSubExpr());
252    break;
253  }
254
255  case CastExpr::CK_DerivedToBaseMemberPointer:
256  case CastExpr::CK_BaseToDerivedMemberPointer: {
257    QualType SrcType = E->getSubExpr()->getType();
258
259    llvm::Value *Src = CGF.CreateMemTemp(SrcType, "tmp");
260    CGF.EmitAggExpr(E->getSubExpr(), Src, SrcType.isVolatileQualified());
261
262    llvm::Value *SrcPtr = Builder.CreateStructGEP(Src, 0, "src.ptr");
263    SrcPtr = Builder.CreateLoad(SrcPtr);
264
265    llvm::Value *SrcAdj = Builder.CreateStructGEP(Src, 1, "src.adj");
266    SrcAdj = Builder.CreateLoad(SrcAdj);
267
268    llvm::Value *DstPtr = Builder.CreateStructGEP(DestPtr, 0, "dst.ptr");
269    Builder.CreateStore(SrcPtr, DstPtr, VolatileDest);
270
271    llvm::Value *DstAdj = Builder.CreateStructGEP(DestPtr, 1, "dst.adj");
272
273    // Now See if we need to update the adjustment.
274    const CXXRecordDecl *BaseDecl =
275      cast<CXXRecordDecl>(SrcType->getAs<MemberPointerType>()->
276                          getClass()->getAs<RecordType>()->getDecl());
277    const CXXRecordDecl *DerivedDecl =
278      cast<CXXRecordDecl>(E->getType()->getAs<MemberPointerType>()->
279                          getClass()->getAs<RecordType>()->getDecl());
280    if (E->getCastKind() == CastExpr::CK_DerivedToBaseMemberPointer)
281      std::swap(DerivedDecl, BaseDecl);
282
283    if (llvm::Constant *Adj =
284          CGF.CGM.GetNonVirtualBaseClassOffset(DerivedDecl, E->getBasePath())) {
285      if (E->getCastKind() == CastExpr::CK_DerivedToBaseMemberPointer)
286        SrcAdj = Builder.CreateSub(SrcAdj, Adj, "adj");
287      else
288        SrcAdj = Builder.CreateAdd(SrcAdj, Adj, "adj");
289    }
290
291    Builder.CreateStore(SrcAdj, DstAdj, VolatileDest);
292    break;
293  }
294  }
295}
296
297void AggExprEmitter::VisitCallExpr(const CallExpr *E) {
298  if (E->getCallReturnType()->isReferenceType()) {
299    EmitAggLoadOfLValue(E);
300    return;
301  }
302
303  // If the struct doesn't require GC, we can just pass the destination
304  // directly to EmitCall.
305  if (!RequiresGCollection) {
306    CGF.EmitCallExpr(E, getReturnValueSlot());
307    return;
308  }
309
310  RValue RV = CGF.EmitCallExpr(E);
311  EmitFinalDestCopy(E, RV);
312}
313
314void AggExprEmitter::VisitObjCMessageExpr(ObjCMessageExpr *E) {
315  CGF.EmitObjCMessageExpr(E, getReturnValueSlot());
316}
317
318void AggExprEmitter::VisitObjCPropertyRefExpr(ObjCPropertyRefExpr *E) {
319  CGF.EmitObjCPropertyGet(E, getReturnValueSlot());
320}
321
322void AggExprEmitter::VisitObjCImplicitSetterGetterRefExpr(
323                                   ObjCImplicitSetterGetterRefExpr *E) {
324  CGF.EmitObjCPropertyGet(E, getReturnValueSlot());
325}
326
327void AggExprEmitter::VisitBinComma(const BinaryOperator *E) {
328  CGF.EmitAnyExpr(E->getLHS(), 0, false, true);
329  CGF.EmitAggExpr(E->getRHS(), DestPtr, VolatileDest,
330                  /*IgnoreResult=*/false, IsInitializer);
331}
332
333void AggExprEmitter::VisitUnaryAddrOf(const UnaryOperator *E) {
334  // We have a member function pointer.
335  const MemberPointerType *MPT = E->getType()->getAs<MemberPointerType>();
336  (void) MPT;
337  assert(MPT->getPointeeType()->isFunctionProtoType() &&
338         "Unexpected member pointer type!");
339
340  // The creation of member function pointers has no side effects; if
341  // there is no destination pointer, we have nothing to do.
342  if (!DestPtr)
343    return;
344
345  const DeclRefExpr *DRE = cast<DeclRefExpr>(E->getSubExpr());
346  const CXXMethodDecl *MD =
347    cast<CXXMethodDecl>(DRE->getDecl())->getCanonicalDecl();
348
349  const llvm::Type *PtrDiffTy =
350    CGF.ConvertType(CGF.getContext().getPointerDiffType());
351
352
353  llvm::Value *DstPtr = Builder.CreateStructGEP(DestPtr, 0, "dst.ptr");
354  llvm::Value *FuncPtr;
355
356  if (MD->isVirtual()) {
357    int64_t Index = CGF.CGM.getVTables().getMethodVTableIndex(MD);
358
359    // FIXME: We shouldn't use / 8 here.
360    uint64_t PointerWidthInBytes =
361      CGF.CGM.getContext().Target.getPointerWidth(0) / 8;
362
363    // Itanium C++ ABI 2.3:
364    //   For a non-virtual function, this field is a simple function pointer.
365    //   For a virtual function, it is 1 plus the virtual table offset
366    //   (in bytes) of the function, represented as a ptrdiff_t.
367    FuncPtr = llvm::ConstantInt::get(PtrDiffTy,
368                                     (Index * PointerWidthInBytes) + 1);
369  } else {
370    const FunctionProtoType *FPT = MD->getType()->getAs<FunctionProtoType>();
371    const llvm::Type *Ty =
372      CGF.CGM.getTypes().GetFunctionType(CGF.CGM.getTypes().getFunctionInfo(MD),
373                                         FPT->isVariadic());
374    llvm::Constant *Fn = CGF.CGM.GetAddrOfFunction(MD, Ty);
375    FuncPtr = llvm::ConstantExpr::getPtrToInt(Fn, PtrDiffTy);
376  }
377  Builder.CreateStore(FuncPtr, DstPtr, VolatileDest);
378
379  llvm::Value *AdjPtr = Builder.CreateStructGEP(DestPtr, 1, "dst.adj");
380
381  // The adjustment will always be 0.
382  Builder.CreateStore(llvm::ConstantInt::get(PtrDiffTy, 0), AdjPtr,
383                      VolatileDest);
384}
385
386void AggExprEmitter::VisitStmtExpr(const StmtExpr *E) {
387  CGF.EmitCompoundStmt(*E->getSubStmt(), true, DestPtr, VolatileDest);
388}
389
390void AggExprEmitter::VisitBinaryOperator(const BinaryOperator *E) {
391  if (E->getOpcode() == BinaryOperator::PtrMemD ||
392      E->getOpcode() == BinaryOperator::PtrMemI)
393    VisitPointerToDataMemberBinaryOperator(E);
394  else
395    CGF.ErrorUnsupported(E, "aggregate binary expression");
396}
397
398void AggExprEmitter::VisitPointerToDataMemberBinaryOperator(
399                                                    const BinaryOperator *E) {
400  LValue LV = CGF.EmitPointerToDataMemberBinaryExpr(E);
401  EmitFinalDestCopy(E, LV);
402}
403
404void AggExprEmitter::VisitBinAssign(const BinaryOperator *E) {
405  // For an assignment to work, the value on the right has
406  // to be compatible with the value on the left.
407  assert(CGF.getContext().hasSameUnqualifiedType(E->getLHS()->getType(),
408                                                 E->getRHS()->getType())
409         && "Invalid assignment");
410  LValue LHS = CGF.EmitLValue(E->getLHS());
411
412  // We have to special case property setters, otherwise we must have
413  // a simple lvalue (no aggregates inside vectors, bitfields).
414  if (LHS.isPropertyRef()) {
415    llvm::Value *AggLoc = DestPtr;
416    if (!AggLoc)
417      AggLoc = CGF.CreateMemTemp(E->getRHS()->getType());
418    CGF.EmitAggExpr(E->getRHS(), AggLoc, VolatileDest);
419    CGF.EmitObjCPropertySet(LHS.getPropertyRefExpr(),
420                            RValue::getAggregate(AggLoc, VolatileDest));
421  } else if (LHS.isKVCRef()) {
422    llvm::Value *AggLoc = DestPtr;
423    if (!AggLoc)
424      AggLoc = CGF.CreateMemTemp(E->getRHS()->getType());
425    CGF.EmitAggExpr(E->getRHS(), AggLoc, VolatileDest);
426    CGF.EmitObjCPropertySet(LHS.getKVCRefExpr(),
427                            RValue::getAggregate(AggLoc, VolatileDest));
428  } else {
429    bool RequiresGCollection = false;
430    if (CGF.getContext().getLangOptions().NeXTRuntime) {
431      QualType LHSTy = E->getLHS()->getType();
432      if (const RecordType *FDTTy = LHSTy.getTypePtr()->getAs<RecordType>())
433        RequiresGCollection = FDTTy->getDecl()->hasObjectMember();
434    }
435    // Codegen the RHS so that it stores directly into the LHS.
436    CGF.EmitAggExpr(E->getRHS(), LHS.getAddress(), LHS.isVolatileQualified(),
437                    false, false, RequiresGCollection);
438    EmitFinalDestCopy(E, LHS, true);
439  }
440}
441
442void AggExprEmitter::VisitConditionalOperator(const ConditionalOperator *E) {
443  if (!E->getLHS()) {
444    CGF.ErrorUnsupported(E, "conditional operator with missing LHS");
445    return;
446  }
447
448  llvm::BasicBlock *LHSBlock = CGF.createBasicBlock("cond.true");
449  llvm::BasicBlock *RHSBlock = CGF.createBasicBlock("cond.false");
450  llvm::BasicBlock *ContBlock = CGF.createBasicBlock("cond.end");
451
452  CGF.EmitBranchOnBoolExpr(E->getCond(), LHSBlock, RHSBlock);
453
454  CGF.BeginConditionalBranch();
455  CGF.EmitBlock(LHSBlock);
456
457  // Handle the GNU extension for missing LHS.
458  assert(E->getLHS() && "Must have LHS for aggregate value");
459
460  Visit(E->getLHS());
461  CGF.EndConditionalBranch();
462  CGF.EmitBranch(ContBlock);
463
464  CGF.BeginConditionalBranch();
465  CGF.EmitBlock(RHSBlock);
466
467  Visit(E->getRHS());
468  CGF.EndConditionalBranch();
469  CGF.EmitBranch(ContBlock);
470
471  CGF.EmitBlock(ContBlock);
472}
473
474void AggExprEmitter::VisitChooseExpr(const ChooseExpr *CE) {
475  Visit(CE->getChosenSubExpr(CGF.getContext()));
476}
477
478void AggExprEmitter::VisitVAArgExpr(VAArgExpr *VE) {
479  llvm::Value *ArgValue = CGF.EmitVAListRef(VE->getSubExpr());
480  llvm::Value *ArgPtr = CGF.EmitVAArg(ArgValue, VE->getType());
481
482  if (!ArgPtr) {
483    CGF.ErrorUnsupported(VE, "aggregate va_arg expression");
484    return;
485  }
486
487  EmitFinalDestCopy(VE, LValue::MakeAddr(ArgPtr, Qualifiers()));
488}
489
490void AggExprEmitter::VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E) {
491  llvm::Value *Val = DestPtr;
492
493  if (!Val) {
494    // Create a temporary variable.
495    Val = CGF.CreateMemTemp(E->getType(), "tmp");
496
497    // FIXME: volatile
498    CGF.EmitAggExpr(E->getSubExpr(), Val, false);
499  } else
500    Visit(E->getSubExpr());
501
502  // Don't make this a live temporary if we're emitting an initializer expr.
503  if (!IsInitializer)
504    CGF.PushCXXTemporary(E->getTemporary(), Val);
505}
506
507void
508AggExprEmitter::VisitCXXConstructExpr(const CXXConstructExpr *E) {
509  llvm::Value *Val = DestPtr;
510
511  if (!Val) {
512    // Create a temporary variable.
513    Val = CGF.CreateMemTemp(E->getType(), "tmp");
514  }
515
516  if (E->requiresZeroInitialization())
517    EmitNullInitializationToLValue(LValue::MakeAddr(Val,
518                                                    // FIXME: Qualifiers()?
519                                                 E->getType().getQualifiers()),
520                                   E->getType());
521
522  CGF.EmitCXXConstructExpr(Val, E);
523}
524
525void AggExprEmitter::VisitCXXExprWithTemporaries(CXXExprWithTemporaries *E) {
526  llvm::Value *Val = DestPtr;
527
528  CGF.EmitCXXExprWithTemporaries(E, Val, VolatileDest, IsInitializer);
529}
530
531void AggExprEmitter::VisitCXXZeroInitValueExpr(CXXZeroInitValueExpr *E) {
532  llvm::Value *Val = DestPtr;
533
534  if (!Val) {
535    // Create a temporary variable.
536    Val = CGF.CreateMemTemp(E->getType(), "tmp");
537  }
538  LValue LV = LValue::MakeAddr(Val, Qualifiers());
539  EmitNullInitializationToLValue(LV, E->getType());
540}
541
542void AggExprEmitter::VisitImplicitValueInitExpr(ImplicitValueInitExpr *E) {
543  llvm::Value *Val = DestPtr;
544
545  if (!Val) {
546    // Create a temporary variable.
547    Val = CGF.CreateMemTemp(E->getType(), "tmp");
548  }
549  LValue LV = LValue::MakeAddr(Val, Qualifiers());
550  EmitNullInitializationToLValue(LV, E->getType());
551}
552
553void
554AggExprEmitter::EmitInitializationToLValue(Expr* E, LValue LV, QualType T) {
555  // FIXME: Ignore result?
556  // FIXME: Are initializers affected by volatile?
557  if (isa<ImplicitValueInitExpr>(E)) {
558    EmitNullInitializationToLValue(LV, T);
559  } else if (T->isReferenceType()) {
560    RValue RV = CGF.EmitReferenceBindingToExpr(E, /*IsInitializer=*/false);
561    CGF.EmitStoreThroughLValue(RV, LV, T);
562  } else if (T->isAnyComplexType()) {
563    CGF.EmitComplexExprIntoAddr(E, LV.getAddress(), false);
564  } else if (CGF.hasAggregateLLVMType(T)) {
565    CGF.EmitAnyExpr(E, LV.getAddress(), false);
566  } else {
567    CGF.EmitStoreThroughLValue(CGF.EmitAnyExpr(E), LV, T);
568  }
569}
570
571void AggExprEmitter::EmitNullInitializationToLValue(LValue LV, QualType T) {
572  if (!CGF.hasAggregateLLVMType(T)) {
573    // For non-aggregates, we can store zero
574    llvm::Value *Null = llvm::Constant::getNullValue(CGF.ConvertType(T));
575    CGF.EmitStoreThroughLValue(RValue::get(Null), LV, T);
576  } else {
577    // Otherwise, just memset the whole thing to zero.  This is legal
578    // because in LLVM, all default initializers are guaranteed to have a
579    // bit pattern of all zeros.
580    // FIXME: That isn't true for member pointers!
581    // There's a potential optimization opportunity in combining
582    // memsets; that would be easy for arrays, but relatively
583    // difficult for structures with the current code.
584    CGF.EmitMemSetToZero(LV.getAddress(), T);
585  }
586}
587
588void AggExprEmitter::VisitInitListExpr(InitListExpr *E) {
589#if 0
590  // FIXME: Assess perf here?  Figure out what cases are worth optimizing here
591  // (Length of globals? Chunks of zeroed-out space?).
592  //
593  // If we can, prefer a copy from a global; this is a lot less code for long
594  // globals, and it's easier for the current optimizers to analyze.
595  if (llvm::Constant* C = CGF.CGM.EmitConstantExpr(E, E->getType(), &CGF)) {
596    llvm::GlobalVariable* GV =
597    new llvm::GlobalVariable(CGF.CGM.getModule(), C->getType(), true,
598                             llvm::GlobalValue::InternalLinkage, C, "");
599    EmitFinalDestCopy(E, LValue::MakeAddr(GV, Qualifiers()));
600    return;
601  }
602#endif
603  if (E->hadArrayRangeDesignator()) {
604    CGF.ErrorUnsupported(E, "GNU array range designator extension");
605  }
606
607  // Handle initialization of an array.
608  if (E->getType()->isArrayType()) {
609    const llvm::PointerType *APType =
610      cast<llvm::PointerType>(DestPtr->getType());
611    const llvm::ArrayType *AType =
612      cast<llvm::ArrayType>(APType->getElementType());
613
614    uint64_t NumInitElements = E->getNumInits();
615
616    if (E->getNumInits() > 0) {
617      QualType T1 = E->getType();
618      QualType T2 = E->getInit(0)->getType();
619      if (CGF.getContext().hasSameUnqualifiedType(T1, T2)) {
620        EmitAggLoadOfLValue(E->getInit(0));
621        return;
622      }
623    }
624
625    uint64_t NumArrayElements = AType->getNumElements();
626    QualType ElementType = CGF.getContext().getCanonicalType(E->getType());
627    ElementType = CGF.getContext().getAsArrayType(ElementType)->getElementType();
628
629    // FIXME: were we intentionally ignoring address spaces and GC attributes?
630    Qualifiers Quals = CGF.MakeQualifiers(ElementType);
631
632    for (uint64_t i = 0; i != NumArrayElements; ++i) {
633      llvm::Value *NextVal = Builder.CreateStructGEP(DestPtr, i, ".array");
634      if (i < NumInitElements)
635        EmitInitializationToLValue(E->getInit(i),
636                                   LValue::MakeAddr(NextVal, Quals),
637                                   ElementType);
638      else
639        EmitNullInitializationToLValue(LValue::MakeAddr(NextVal, Quals),
640                                       ElementType);
641    }
642    return;
643  }
644
645  assert(E->getType()->isRecordType() && "Only support structs/unions here!");
646
647  // Do struct initialization; this code just sets each individual member
648  // to the approprate value.  This makes bitfield support automatic;
649  // the disadvantage is that the generated code is more difficult for
650  // the optimizer, especially with bitfields.
651  unsigned NumInitElements = E->getNumInits();
652  RecordDecl *SD = E->getType()->getAs<RecordType>()->getDecl();
653  unsigned CurInitVal = 0;
654
655  if (E->getType()->isUnionType()) {
656    // Only initialize one field of a union. The field itself is
657    // specified by the initializer list.
658    if (!E->getInitializedFieldInUnion()) {
659      // Empty union; we have nothing to do.
660
661#ifndef NDEBUG
662      // Make sure that it's really an empty and not a failure of
663      // semantic analysis.
664      for (RecordDecl::field_iterator Field = SD->field_begin(),
665                                   FieldEnd = SD->field_end();
666           Field != FieldEnd; ++Field)
667        assert(Field->isUnnamedBitfield() && "Only unnamed bitfields allowed");
668#endif
669      return;
670    }
671
672    // FIXME: volatility
673    FieldDecl *Field = E->getInitializedFieldInUnion();
674    LValue FieldLoc = CGF.EmitLValueForFieldInitialization(DestPtr, Field, 0);
675
676    if (NumInitElements) {
677      // Store the initializer into the field
678      EmitInitializationToLValue(E->getInit(0), FieldLoc, Field->getType());
679    } else {
680      // Default-initialize to null
681      EmitNullInitializationToLValue(FieldLoc, Field->getType());
682    }
683
684    return;
685  }
686
687  // If we're initializing the whole aggregate, just do it in place.
688  // FIXME: This is a hack around an AST bug (PR6537).
689  if (NumInitElements == 1 && E->getType() == E->getInit(0)->getType()) {
690    EmitInitializationToLValue(E->getInit(0),
691                               LValue::MakeAddr(DestPtr, Qualifiers()),
692                               E->getType());
693    return;
694  }
695
696
697  // Here we iterate over the fields; this makes it simpler to both
698  // default-initialize fields and skip over unnamed fields.
699  for (RecordDecl::field_iterator Field = SD->field_begin(),
700                               FieldEnd = SD->field_end();
701       Field != FieldEnd; ++Field) {
702    // We're done once we hit the flexible array member
703    if (Field->getType()->isIncompleteArrayType())
704      break;
705
706    if (Field->isUnnamedBitfield())
707      continue;
708
709    // FIXME: volatility
710    LValue FieldLoc = CGF.EmitLValueForFieldInitialization(DestPtr, *Field, 0);
711    // We never generate write-barries for initialized fields.
712    LValue::SetObjCNonGC(FieldLoc, true);
713    if (CurInitVal < NumInitElements) {
714      // Store the initializer into the field.
715      EmitInitializationToLValue(E->getInit(CurInitVal++), FieldLoc,
716                                 Field->getType());
717    } else {
718      // We're out of initalizers; default-initialize to null
719      EmitNullInitializationToLValue(FieldLoc, Field->getType());
720    }
721  }
722}
723
724//===----------------------------------------------------------------------===//
725//                        Entry Points into this File
726//===----------------------------------------------------------------------===//
727
728/// EmitAggExpr - Emit the computation of the specified expression of aggregate
729/// type.  The result is computed into DestPtr.  Note that if DestPtr is null,
730/// the value of the aggregate expression is not needed.  If VolatileDest is
731/// true, DestPtr cannot be 0.
732//
733// FIXME: Take Qualifiers object.
734void CodeGenFunction::EmitAggExpr(const Expr *E, llvm::Value *DestPtr,
735                                  bool VolatileDest, bool IgnoreResult,
736                                  bool IsInitializer,
737                                  bool RequiresGCollection) {
738  assert(E && hasAggregateLLVMType(E->getType()) &&
739         "Invalid aggregate expression to emit");
740  assert ((DestPtr != 0 || VolatileDest == false)
741          && "volatile aggregate can't be 0");
742
743  AggExprEmitter(*this, DestPtr, VolatileDest, IgnoreResult, IsInitializer,
744                 RequiresGCollection)
745    .Visit(const_cast<Expr*>(E));
746}
747
748LValue CodeGenFunction::EmitAggExprToLValue(const Expr *E) {
749  assert(hasAggregateLLVMType(E->getType()) && "Invalid argument!");
750  Qualifiers Q = MakeQualifiers(E->getType());
751  llvm::Value *Temp = CreateMemTemp(E->getType());
752  EmitAggExpr(E, Temp, Q.hasVolatile());
753  return LValue::MakeAddr(Temp, Q);
754}
755
756void CodeGenFunction::EmitAggregateCopy(llvm::Value *DestPtr,
757                                        llvm::Value *SrcPtr, QualType Ty,
758                                        bool isVolatile) {
759  assert(!Ty->isAnyComplexType() && "Shouldn't happen for complex");
760
761  if (getContext().getLangOptions().CPlusPlus) {
762    if (const RecordType *RT = Ty->getAs<RecordType>()) {
763      CXXRecordDecl *Record = cast<CXXRecordDecl>(RT->getDecl());
764      assert((Record->hasTrivialCopyConstructor() ||
765              Record->hasTrivialCopyAssignment()) &&
766             "Trying to aggregate-copy a type without a trivial copy "
767             "constructor or assignment operator");
768      // Ignore empty classes in C++.
769      if (Record->isEmpty())
770        return;
771    }
772  }
773
774  // Aggregate assignment turns into llvm.memcpy.  This is almost valid per
775  // C99 6.5.16.1p3, which states "If the value being stored in an object is
776  // read from another object that overlaps in anyway the storage of the first
777  // object, then the overlap shall be exact and the two objects shall have
778  // qualified or unqualified versions of a compatible type."
779  //
780  // memcpy is not defined if the source and destination pointers are exactly
781  // equal, but other compilers do this optimization, and almost every memcpy
782  // implementation handles this case safely.  If there is a libc that does not
783  // safely handle this, we can add a target hook.
784  const llvm::Type *BP = llvm::Type::getInt8PtrTy(VMContext);
785  if (DestPtr->getType() != BP)
786    DestPtr = Builder.CreateBitCast(DestPtr, BP, "tmp");
787  if (SrcPtr->getType() != BP)
788    SrcPtr = Builder.CreateBitCast(SrcPtr, BP, "tmp");
789
790  // Get size and alignment info for this aggregate.
791  std::pair<uint64_t, unsigned> TypeInfo = getContext().getTypeInfo(Ty);
792
793  // FIXME: Handle variable sized types.
794  const llvm::Type *IntPtr =
795          llvm::IntegerType::get(VMContext, LLVMPointerWidth);
796
797  // FIXME: If we have a volatile struct, the optimizer can remove what might
798  // appear to be `extra' memory ops:
799  //
800  // volatile struct { int i; } a, b;
801  //
802  // int main() {
803  //   a = b;
804  //   a = b;
805  // }
806  //
807  // we need to use a different call here.  We use isVolatile to indicate when
808  // either the source or the destination is volatile.
809  const llvm::Type *I1Ty = llvm::Type::getInt1Ty(VMContext);
810  const llvm::Type *I8Ty = llvm::Type::getInt8Ty(VMContext);
811  const llvm::Type *I32Ty = llvm::Type::getInt32Ty(VMContext);
812
813  const llvm::PointerType *DPT = cast<llvm::PointerType>(DestPtr->getType());
814  const llvm::Type *DBP = llvm::PointerType::get(I8Ty, DPT->getAddressSpace());
815  if (DestPtr->getType() != DBP)
816    DestPtr = Builder.CreateBitCast(DestPtr, DBP, "tmp");
817
818  const llvm::PointerType *SPT = cast<llvm::PointerType>(SrcPtr->getType());
819  const llvm::Type *SBP = llvm::PointerType::get(I8Ty, SPT->getAddressSpace());
820  if (SrcPtr->getType() != SBP)
821    SrcPtr = Builder.CreateBitCast(SrcPtr, SBP, "tmp");
822
823  Builder.CreateCall5(CGM.getMemCpyFn(DestPtr->getType(), SrcPtr->getType(),
824                                      IntPtr),
825                      DestPtr, SrcPtr,
826                      // TypeInfo.first describes size in bits.
827                      llvm::ConstantInt::get(IntPtr, TypeInfo.first/8),
828                      llvm::ConstantInt::get(I32Ty,  TypeInfo.second/8),
829                      llvm::ConstantInt::get(I1Ty,  isVolatile));
830}
831