CGExprAgg.cpp revision e8a81f7e8e26275d91c073bf908a7d6d246106c5 
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 VisitImplicitValueInitExpr(ImplicitValueInitExpr *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, QualType T);
122  void EmitNullInitializationToLValue(LValue Address, QualType T);
123  //  case Expr::ChooseExprClass:
124  void VisitCXXThrowExpr(const CXXThrowExpr *E) { CGF.EmitCXXThrowExpr(E); }
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                               E->getType());
193    break;
194  }
195
196  // FIXME: Remove the CK_Unknown check here.
197  case CastExpr::CK_Unknown:
198  case CastExpr::CK_NoOp:
199  case CastExpr::CK_UserDefinedConversion:
200  case CastExpr::CK_ConstructorConversion:
201    assert(CGF.getContext().hasSameUnqualifiedType(E->getSubExpr()->getType(),
202                                                   E->getType()) &&
203           "Implicit cast types must be compatible");
204    Visit(E->getSubExpr());
205    break;
206
207  case CastExpr::CK_NullToMemberPointer: {
208    const llvm::Type *PtrDiffTy =
209      CGF.ConvertType(CGF.getContext().getPointerDiffType());
210
211    llvm::Value *NullValue = llvm::Constant::getNullValue(PtrDiffTy);
212    llvm::Value *Ptr = Builder.CreateStructGEP(DestPtr, 0, "ptr");
213    Builder.CreateStore(NullValue, Ptr, VolatileDest);
214
215    llvm::Value *Adj = Builder.CreateStructGEP(DestPtr, 1, "adj");
216    Builder.CreateStore(NullValue, Adj, VolatileDest);
217
218    break;
219  }
220
221  case CastExpr::CK_BitCast: {
222    // This must be a member function pointer cast.
223    Visit(E->getSubExpr());
224    break;
225  }
226
227  case CastExpr::CK_DerivedToBaseMemberPointer:
228  case CastExpr::CK_BaseToDerivedMemberPointer: {
229    QualType SrcType = E->getSubExpr()->getType();
230
231    llvm::Value *Src = CGF.CreateTempAlloca(CGF.ConvertTypeForMem(SrcType),
232                                            "tmp");
233    CGF.EmitAggExpr(E->getSubExpr(), Src, SrcType.isVolatileQualified());
234
235    llvm::Value *SrcPtr = Builder.CreateStructGEP(Src, 0, "src.ptr");
236    SrcPtr = Builder.CreateLoad(SrcPtr);
237
238    llvm::Value *SrcAdj = Builder.CreateStructGEP(Src, 1, "src.adj");
239    SrcAdj = Builder.CreateLoad(SrcAdj);
240
241    llvm::Value *DstPtr = Builder.CreateStructGEP(DestPtr, 0, "dst.ptr");
242    Builder.CreateStore(SrcPtr, DstPtr, VolatileDest);
243
244    llvm::Value *DstAdj = Builder.CreateStructGEP(DestPtr, 1, "dst.adj");
245
246    // Now See if we need to update the adjustment.
247    const CXXRecordDecl *BaseDecl =
248      cast<CXXRecordDecl>(SrcType->getAs<MemberPointerType>()->
249                          getClass()->getAs<RecordType>()->getDecl());
250    const CXXRecordDecl *DerivedDecl =
251      cast<CXXRecordDecl>(E->getType()->getAs<MemberPointerType>()->
252                          getClass()->getAs<RecordType>()->getDecl());
253    if (E->getCastKind() == CastExpr::CK_DerivedToBaseMemberPointer)
254      std::swap(DerivedDecl, BaseDecl);
255
256    if (llvm::Constant *Adj =
257          CGF.CGM.GetNonVirtualBaseClassOffset(DerivedDecl, BaseDecl)) {
258      if (E->getCastKind() == CastExpr::CK_DerivedToBaseMemberPointer)
259        SrcAdj = Builder.CreateSub(SrcAdj, Adj, "adj");
260      else
261        SrcAdj = Builder.CreateAdd(SrcAdj, Adj, "adj");
262    }
263
264    Builder.CreateStore(SrcAdj, DstAdj, VolatileDest);
265    break;
266  }
267  }
268}
269
270void AggExprEmitter::VisitCallExpr(const CallExpr *E) {
271  if (E->getCallReturnType()->isReferenceType()) {
272    EmitAggLoadOfLValue(E);
273    return;
274  }
275
276  // If the struct doesn't require GC, we can just pass the destination
277  // directly to EmitCall.
278  if (!RequiresGCollection) {
279    CGF.EmitCallExpr(E, ReturnValueSlot(DestPtr, VolatileDest));
280    return;
281  }
282
283  RValue RV = CGF.EmitCallExpr(E);
284  EmitFinalDestCopy(E, RV);
285}
286
287void AggExprEmitter::VisitObjCMessageExpr(ObjCMessageExpr *E) {
288  RValue RV = CGF.EmitObjCMessageExpr(E);
289  EmitFinalDestCopy(E, RV);
290}
291
292void AggExprEmitter::VisitObjCPropertyRefExpr(ObjCPropertyRefExpr *E) {
293  RValue RV = CGF.EmitObjCPropertyGet(E);
294  EmitFinalDestCopy(E, RV);
295}
296
297void AggExprEmitter::VisitObjCImplicitSetterGetterRefExpr(
298                                   ObjCImplicitSetterGetterRefExpr *E) {
299  RValue RV = CGF.EmitObjCPropertyGet(E);
300  EmitFinalDestCopy(E, RV);
301}
302
303void AggExprEmitter::VisitBinComma(const BinaryOperator *E) {
304  CGF.EmitAnyExpr(E->getLHS(), 0, false, true);
305  CGF.EmitAggExpr(E->getRHS(), DestPtr, VolatileDest,
306                  /*IgnoreResult=*/false, IsInitializer);
307}
308
309void AggExprEmitter::VisitUnaryAddrOf(const UnaryOperator *E) {
310  // We have a member function pointer.
311  const MemberPointerType *MPT = E->getType()->getAs<MemberPointerType>();
312  (void) MPT;
313  assert(MPT->getPointeeType()->isFunctionProtoType() &&
314         "Unexpected member pointer type!");
315
316  const DeclRefExpr *DRE = cast<DeclRefExpr>(E->getSubExpr());
317  const CXXMethodDecl *MD =
318    cast<CXXMethodDecl>(DRE->getDecl())->getCanonicalDecl();
319
320  const llvm::Type *PtrDiffTy =
321    CGF.ConvertType(CGF.getContext().getPointerDiffType());
322
323  llvm::Value *DstPtr = Builder.CreateStructGEP(DestPtr, 0, "dst.ptr");
324  llvm::Value *FuncPtr;
325
326  if (MD->isVirtual()) {
327    int64_t Index =
328      CGF.CGM.getVtableInfo().getMethodVtableIndex(MD);
329
330    // Itanium C++ ABI 2.3:
331    //   For a non-virtual function, this field is a simple function pointer.
332    //   For a virtual function, it is 1 plus the virtual table offset
333    //   (in bytes) of the function, represented as a ptrdiff_t.
334    FuncPtr = llvm::ConstantInt::get(PtrDiffTy, (Index * 8) + 1);
335  } else {
336    FuncPtr = llvm::ConstantExpr::getPtrToInt(CGF.CGM.GetAddrOfFunction(MD),
337                                              PtrDiffTy);
338  }
339  Builder.CreateStore(FuncPtr, DstPtr, VolatileDest);
340
341  llvm::Value *AdjPtr = Builder.CreateStructGEP(DestPtr, 1, "dst.adj");
342
343  // The adjustment will always be 0.
344  Builder.CreateStore(llvm::ConstantInt::get(PtrDiffTy, 0), AdjPtr,
345                      VolatileDest);
346}
347
348void AggExprEmitter::VisitStmtExpr(const StmtExpr *E) {
349  CGF.EmitCompoundStmt(*E->getSubStmt(), true, DestPtr, VolatileDest);
350}
351
352void AggExprEmitter::VisitBinaryOperator(const BinaryOperator *E) {
353  if (E->getOpcode() == BinaryOperator::PtrMemD ||
354      E->getOpcode() == BinaryOperator::PtrMemI)
355    VisitPointerToDataMemberBinaryOperator(E);
356  else
357    CGF.ErrorUnsupported(E, "aggregate binary expression");
358}
359
360void AggExprEmitter::VisitPointerToDataMemberBinaryOperator(
361                                                    const BinaryOperator *E) {
362  LValue LV = CGF.EmitPointerToDataMemberBinaryExpr(E);
363  EmitFinalDestCopy(E, LV);
364}
365
366void AggExprEmitter::VisitBinAssign(const BinaryOperator *E) {
367  // For an assignment to work, the value on the right has
368  // to be compatible with the value on the left.
369  assert(CGF.getContext().hasSameUnqualifiedType(E->getLHS()->getType(),
370                                                 E->getRHS()->getType())
371         && "Invalid assignment");
372  LValue LHS = CGF.EmitLValue(E->getLHS());
373
374  // We have to special case property setters, otherwise we must have
375  // a simple lvalue (no aggregates inside vectors, bitfields).
376  if (LHS.isPropertyRef()) {
377    llvm::Value *AggLoc = DestPtr;
378    if (!AggLoc)
379      AggLoc = CGF.CreateTempAlloca(CGF.ConvertType(E->getRHS()->getType()));
380    CGF.EmitAggExpr(E->getRHS(), AggLoc, VolatileDest);
381    CGF.EmitObjCPropertySet(LHS.getPropertyRefExpr(),
382                            RValue::getAggregate(AggLoc, VolatileDest));
383  } else if (LHS.isKVCRef()) {
384    llvm::Value *AggLoc = DestPtr;
385    if (!AggLoc)
386      AggLoc = CGF.CreateTempAlloca(CGF.ConvertType(E->getRHS()->getType()));
387    CGF.EmitAggExpr(E->getRHS(), AggLoc, VolatileDest);
388    CGF.EmitObjCPropertySet(LHS.getKVCRefExpr(),
389                            RValue::getAggregate(AggLoc, VolatileDest));
390  } else {
391    bool RequiresGCollection = false;
392    if (CGF.getContext().getLangOptions().NeXTRuntime) {
393      QualType LHSTy = E->getLHS()->getType();
394      if (const RecordType *FDTTy = LHSTy.getTypePtr()->getAs<RecordType>())
395        RequiresGCollection = FDTTy->getDecl()->hasObjectMember();
396    }
397    // Codegen the RHS so that it stores directly into the LHS.
398    CGF.EmitAggExpr(E->getRHS(), LHS.getAddress(), LHS.isVolatileQualified(),
399                    false, false, RequiresGCollection);
400    EmitFinalDestCopy(E, LHS, true);
401  }
402}
403
404void AggExprEmitter::VisitConditionalOperator(const ConditionalOperator *E) {
405  if (!E->getLHS()) {
406    CGF.ErrorUnsupported(E, "conditional operator with missing LHS");
407    return;
408  }
409
410  llvm::BasicBlock *LHSBlock = CGF.createBasicBlock("cond.true");
411  llvm::BasicBlock *RHSBlock = CGF.createBasicBlock("cond.false");
412  llvm::BasicBlock *ContBlock = CGF.createBasicBlock("cond.end");
413
414  CGF.EmitBranchOnBoolExpr(E->getCond(), LHSBlock, RHSBlock);
415
416  CGF.StartConditionalBranch();
417  CGF.EmitBlock(LHSBlock);
418
419  // Handle the GNU extension for missing LHS.
420  assert(E->getLHS() && "Must have LHS for aggregate value");
421
422  Visit(E->getLHS());
423  CGF.FinishConditionalBranch();
424  CGF.EmitBranch(ContBlock);
425
426  CGF.StartConditionalBranch();
427  CGF.EmitBlock(RHSBlock);
428
429  Visit(E->getRHS());
430  CGF.FinishConditionalBranch();
431  CGF.EmitBranch(ContBlock);
432
433  CGF.EmitBlock(ContBlock);
434}
435
436void AggExprEmitter::VisitChooseExpr(const ChooseExpr *CE) {
437  Visit(CE->getChosenSubExpr(CGF.getContext()));
438}
439
440void AggExprEmitter::VisitVAArgExpr(VAArgExpr *VE) {
441  llvm::Value *ArgValue = CGF.EmitVAListRef(VE->getSubExpr());
442  llvm::Value *ArgPtr = CGF.EmitVAArg(ArgValue, VE->getType());
443
444  if (!ArgPtr) {
445    CGF.ErrorUnsupported(VE, "aggregate va_arg expression");
446    return;
447  }
448
449  EmitFinalDestCopy(VE, LValue::MakeAddr(ArgPtr, Qualifiers()));
450}
451
452void AggExprEmitter::VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *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    // FIXME: volatile
460    CGF.EmitAggExpr(E->getSubExpr(), Val, false);
461  } else
462    Visit(E->getSubExpr());
463
464  // Don't make this a live temporary if we're emitting an initializer expr.
465  if (!IsInitializer)
466    CGF.PushCXXTemporary(E->getTemporary(), Val);
467}
468
469void
470AggExprEmitter::VisitCXXConstructExpr(const CXXConstructExpr *E) {
471  llvm::Value *Val = DestPtr;
472
473  if (!Val) {
474    // Create a temporary variable.
475    Val = CGF.CreateTempAlloca(CGF.ConvertTypeForMem(E->getType()), "tmp");
476  }
477
478  if (E->requiresZeroInitialization())
479    EmitNullInitializationToLValue(LValue::MakeAddr(Val,
480                                                    // FIXME: Qualifiers()?
481                                                 E->getType().getQualifiers()),
482                                   E->getType());
483
484  CGF.EmitCXXConstructExpr(Val, E);
485}
486
487void AggExprEmitter::VisitCXXExprWithTemporaries(CXXExprWithTemporaries *E) {
488  llvm::Value *Val = DestPtr;
489
490  if (!Val) {
491    // Create a temporary variable.
492    Val = CGF.CreateTempAlloca(CGF.ConvertTypeForMem(E->getType()), "tmp");
493  }
494  CGF.EmitCXXExprWithTemporaries(E, Val, VolatileDest, IsInitializer);
495}
496
497void AggExprEmitter::VisitCXXZeroInitValueExpr(CXXZeroInitValueExpr *E) {
498  llvm::Value *Val = DestPtr;
499
500  if (!Val) {
501    // Create a temporary variable.
502    Val = CGF.CreateTempAlloca(CGF.ConvertTypeForMem(E->getType()), "tmp");
503  }
504  LValue LV = LValue::MakeAddr(Val, Qualifiers());
505  EmitNullInitializationToLValue(LV, E->getType());
506}
507
508void AggExprEmitter::VisitImplicitValueInitExpr(ImplicitValueInitExpr *E) {
509  llvm::Value *Val = DestPtr;
510
511  if (!Val) {
512    // Create a temporary variable.
513    Val = CGF.CreateTempAlloca(CGF.ConvertTypeForMem(E->getType()), "tmp");
514  }
515  LValue LV = LValue::MakeAddr(Val, Qualifiers());
516  EmitNullInitializationToLValue(LV, E->getType());
517}
518
519void
520AggExprEmitter::EmitInitializationToLValue(Expr* E, LValue LV, QualType T) {
521  // FIXME: Ignore result?
522  // FIXME: Are initializers affected by volatile?
523  if (isa<ImplicitValueInitExpr>(E)) {
524    EmitNullInitializationToLValue(LV, T);
525  } else if (T->isReferenceType()) {
526    RValue RV = CGF.EmitReferenceBindingToExpr(E, /*IsInitializer=*/false);
527    CGF.EmitStoreThroughLValue(RV, LV, T);
528  } else if (T->isAnyComplexType()) {
529    CGF.EmitComplexExprIntoAddr(E, LV.getAddress(), false);
530  } else if (CGF.hasAggregateLLVMType(T)) {
531    CGF.EmitAnyExpr(E, LV.getAddress(), false);
532  } else {
533    CGF.EmitStoreThroughLValue(CGF.EmitAnyExpr(E), LV, T);
534  }
535}
536
537void AggExprEmitter::EmitNullInitializationToLValue(LValue LV, QualType T) {
538  if (!CGF.hasAggregateLLVMType(T)) {
539    // For non-aggregates, we can store zero
540    llvm::Value *Null = llvm::Constant::getNullValue(CGF.ConvertType(T));
541    CGF.EmitStoreThroughLValue(RValue::get(Null), LV, T);
542  } else {
543    // Otherwise, just memset the whole thing to zero.  This is legal
544    // because in LLVM, all default initializers are guaranteed to have a
545    // bit pattern of all zeros.
546    // FIXME: That isn't true for member pointers!
547    // There's a potential optimization opportunity in combining
548    // memsets; that would be easy for arrays, but relatively
549    // difficult for structures with the current code.
550    CGF.EmitMemSetToZero(LV.getAddress(), T);
551  }
552}
553
554void AggExprEmitter::VisitInitListExpr(InitListExpr *E) {
555#if 0
556  // FIXME: Assess perf here?  Figure out what cases are worth optimizing here
557  // (Length of globals? Chunks of zeroed-out space?).
558  //
559  // If we can, prefer a copy from a global; this is a lot less code for long
560  // globals, and it's easier for the current optimizers to analyze.
561  if (llvm::Constant* C = CGF.CGM.EmitConstantExpr(E, E->getType(), &CGF)) {
562    llvm::GlobalVariable* GV =
563    new llvm::GlobalVariable(CGF.CGM.getModule(), C->getType(), true,
564                             llvm::GlobalValue::InternalLinkage, C, "");
565    EmitFinalDestCopy(E, LValue::MakeAddr(GV, Qualifiers()));
566    return;
567  }
568#endif
569  if (E->hadArrayRangeDesignator()) {
570    CGF.ErrorUnsupported(E, "GNU array range designator extension");
571  }
572
573  // Handle initialization of an array.
574  if (E->getType()->isArrayType()) {
575    const llvm::PointerType *APType =
576      cast<llvm::PointerType>(DestPtr->getType());
577    const llvm::ArrayType *AType =
578      cast<llvm::ArrayType>(APType->getElementType());
579
580    uint64_t NumInitElements = E->getNumInits();
581
582    if (E->getNumInits() > 0) {
583      QualType T1 = E->getType();
584      QualType T2 = E->getInit(0)->getType();
585      if (CGF.getContext().hasSameUnqualifiedType(T1, T2)) {
586        EmitAggLoadOfLValue(E->getInit(0));
587        return;
588      }
589    }
590
591    uint64_t NumArrayElements = AType->getNumElements();
592    QualType ElementType = CGF.getContext().getCanonicalType(E->getType());
593    ElementType = CGF.getContext().getAsArrayType(ElementType)->getElementType();
594
595    // FIXME: were we intentionally ignoring address spaces and GC attributes?
596    Qualifiers Quals = CGF.MakeQualifiers(ElementType);
597
598    for (uint64_t i = 0; i != NumArrayElements; ++i) {
599      llvm::Value *NextVal = Builder.CreateStructGEP(DestPtr, i, ".array");
600      if (i < NumInitElements)
601        EmitInitializationToLValue(E->getInit(i),
602                                   LValue::MakeAddr(NextVal, Quals),
603                                   ElementType);
604      else
605        EmitNullInitializationToLValue(LValue::MakeAddr(NextVal, Quals),
606                                       ElementType);
607    }
608    return;
609  }
610
611  assert(E->getType()->isRecordType() && "Only support structs/unions here!");
612
613  // Do struct initialization; this code just sets each individual member
614  // to the approprate value.  This makes bitfield support automatic;
615  // the disadvantage is that the generated code is more difficult for
616  // the optimizer, especially with bitfields.
617  unsigned NumInitElements = E->getNumInits();
618  RecordDecl *SD = E->getType()->getAs<RecordType>()->getDecl();
619  unsigned CurInitVal = 0;
620
621  if (E->getType()->isUnionType()) {
622    // Only initialize one field of a union. The field itself is
623    // specified by the initializer list.
624    if (!E->getInitializedFieldInUnion()) {
625      // Empty union; we have nothing to do.
626
627#ifndef NDEBUG
628      // Make sure that it's really an empty and not a failure of
629      // semantic analysis.
630      for (RecordDecl::field_iterator Field = SD->field_begin(),
631                                   FieldEnd = SD->field_end();
632           Field != FieldEnd; ++Field)
633        assert(Field->isUnnamedBitfield() && "Only unnamed bitfields allowed");
634#endif
635      return;
636    }
637
638    // FIXME: volatility
639    FieldDecl *Field = E->getInitializedFieldInUnion();
640    LValue FieldLoc = CGF.EmitLValueForFieldInitialization(DestPtr, Field, 0);
641
642    if (NumInitElements) {
643      // Store the initializer into the field
644      EmitInitializationToLValue(E->getInit(0), FieldLoc, Field->getType());
645    } else {
646      // Default-initialize to null
647      EmitNullInitializationToLValue(FieldLoc, Field->getType());
648    }
649
650    return;
651  }
652
653  // Here we iterate over the fields; this makes it simpler to both
654  // default-initialize fields and skip over unnamed fields.
655  for (RecordDecl::field_iterator Field = SD->field_begin(),
656                               FieldEnd = SD->field_end();
657       Field != FieldEnd; ++Field) {
658    // We're done once we hit the flexible array member
659    if (Field->getType()->isIncompleteArrayType())
660      break;
661
662    if (Field->isUnnamedBitfield())
663      continue;
664
665    // FIXME: volatility
666    LValue FieldLoc = CGF.EmitLValueForFieldInitialization(DestPtr, *Field, 0);
667    // We never generate write-barries for initialized fields.
668    LValue::SetObjCNonGC(FieldLoc, true);
669    if (CurInitVal < NumInitElements) {
670      // Store the initializer into the field
671      EmitInitializationToLValue(E->getInit(CurInitVal++), FieldLoc,
672                                 Field->getType());
673    } else {
674      // We're out of initalizers; default-initialize to null
675      EmitNullInitializationToLValue(FieldLoc, Field->getType());
676    }
677  }
678}
679
680//===----------------------------------------------------------------------===//
681//                        Entry Points into this File
682//===----------------------------------------------------------------------===//
683
684/// EmitAggExpr - Emit the computation of the specified expression of aggregate
685/// type.  The result is computed into DestPtr.  Note that if DestPtr is null,
686/// the value of the aggregate expression is not needed.  If VolatileDest is
687/// true, DestPtr cannot be 0.
688void CodeGenFunction::EmitAggExpr(const Expr *E, llvm::Value *DestPtr,
689                                  bool VolatileDest, bool IgnoreResult,
690                                  bool IsInitializer,
691                                  bool RequiresGCollection) {
692  assert(E && hasAggregateLLVMType(E->getType()) &&
693         "Invalid aggregate expression to emit");
694  assert ((DestPtr != 0 || VolatileDest == false)
695          && "volatile aggregate can't be 0");
696
697  AggExprEmitter(*this, DestPtr, VolatileDest, IgnoreResult, IsInitializer,
698                 RequiresGCollection)
699    .Visit(const_cast<Expr*>(E));
700}
701
702void CodeGenFunction::EmitAggregateClear(llvm::Value *DestPtr, QualType Ty) {
703  assert(!Ty->isAnyComplexType() && "Shouldn't happen for complex");
704
705  EmitMemSetToZero(DestPtr, Ty);
706}
707
708void CodeGenFunction::EmitAggregateCopy(llvm::Value *DestPtr,
709                                        llvm::Value *SrcPtr, QualType Ty,
710                                        bool isVolatile) {
711  assert(!Ty->isAnyComplexType() && "Shouldn't happen for complex");
712
713  // Aggregate assignment turns into llvm.memcpy.  This is almost valid per
714  // C99 6.5.16.1p3, which states "If the value being stored in an object is
715  // read from another object that overlaps in anyway the storage of the first
716  // object, then the overlap shall be exact and the two objects shall have
717  // qualified or unqualified versions of a compatible type."
718  //
719  // memcpy is not defined if the source and destination pointers are exactly
720  // equal, but other compilers do this optimization, and almost every memcpy
721  // implementation handles this case safely.  If there is a libc that does not
722  // safely handle this, we can add a target hook.
723  const llvm::Type *BP = llvm::Type::getInt8PtrTy(VMContext);
724  if (DestPtr->getType() != BP)
725    DestPtr = Builder.CreateBitCast(DestPtr, BP, "tmp");
726  if (SrcPtr->getType() != BP)
727    SrcPtr = Builder.CreateBitCast(SrcPtr, BP, "tmp");
728
729  // Get size and alignment info for this aggregate.
730  std::pair<uint64_t, unsigned> TypeInfo = getContext().getTypeInfo(Ty);
731
732  // FIXME: Handle variable sized types.
733  const llvm::Type *IntPtr =
734          llvm::IntegerType::get(VMContext, LLVMPointerWidth);
735
736  // FIXME: If we have a volatile struct, the optimizer can remove what might
737  // appear to be `extra' memory ops:
738  //
739  // volatile struct { int i; } a, b;
740  //
741  // int main() {
742  //   a = b;
743  //   a = b;
744  // }
745  //
746  // we need to use a differnt call here.  We use isVolatile to indicate when
747  // either the source or the destination is volatile.
748  Builder.CreateCall4(CGM.getMemCpyFn(),
749                      DestPtr, SrcPtr,
750                      // TypeInfo.first describes size in bits.
751                      llvm::ConstantInt::get(IntPtr, TypeInfo.first/8),
752                      llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext),
753                                             TypeInfo.second/8));
754}
755