CGExprAgg.cpp revision e6b9d802fb7b16d93474c4f1c179ab36202e8a8b 
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 "CGObjCRuntime.h"
16#include "CodeGenModule.h"
17#include "clang/AST/ASTContext.h"
18#include "clang/AST/DeclCXX.h"
19#include "clang/AST/DeclTemplate.h"
20#include "clang/AST/StmtVisitor.h"
21#include "llvm/IR/Constants.h"
22#include "llvm/IR/Function.h"
23#include "llvm/IR/GlobalVariable.h"
24#include "llvm/IR/Intrinsics.h"
25using namespace clang;
26using namespace CodeGen;
27
28//===----------------------------------------------------------------------===//
29//                        Aggregate Expression Emitter
30//===----------------------------------------------------------------------===//
31
32namespace  {
33class AggExprEmitter : public StmtVisitor<AggExprEmitter> {
34  CodeGenFunction &CGF;
35  CGBuilderTy &Builder;
36  AggValueSlot Dest;
37
38  /// We want to use 'dest' as the return slot except under two
39  /// conditions:
40  ///   - The destination slot requires garbage collection, so we
41  ///     need to use the GC API.
42  ///   - The destination slot is potentially aliased.
43  bool shouldUseDestForReturnSlot() const {
44    return !(Dest.requiresGCollection() || Dest.isPotentiallyAliased());
45  }
46
47  ReturnValueSlot getReturnValueSlot() const {
48    if (!shouldUseDestForReturnSlot())
49      return ReturnValueSlot();
50
51    return ReturnValueSlot(Dest.getAddr(), Dest.isVolatile());
52  }
53
54  AggValueSlot EnsureSlot(QualType T) {
55    if (!Dest.isIgnored()) return Dest;
56    return CGF.CreateAggTemp(T, "agg.tmp.ensured");
57  }
58  void EnsureDest(QualType T) {
59    if (!Dest.isIgnored()) return;
60    Dest = CGF.CreateAggTemp(T, "agg.tmp.ensured");
61  }
62
63public:
64  AggExprEmitter(CodeGenFunction &cgf, AggValueSlot Dest)
65    : CGF(cgf), Builder(CGF.Builder), Dest(Dest) {
66  }
67
68  //===--------------------------------------------------------------------===//
69  //                               Utilities
70  //===--------------------------------------------------------------------===//
71
72  /// EmitAggLoadOfLValue - Given an expression with aggregate type that
73  /// represents a value lvalue, this method emits the address of the lvalue,
74  /// then loads the result into DestPtr.
75  void EmitAggLoadOfLValue(const Expr *E);
76
77  /// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired.
78  void EmitFinalDestCopy(QualType type, const LValue &src);
79  void EmitFinalDestCopy(QualType type, RValue src,
80                         CharUnits srcAlignment = CharUnits::Zero());
81  void EmitCopy(QualType type, const AggValueSlot &dest,
82                const AggValueSlot &src);
83
84  void EmitMoveFromReturnSlot(const Expr *E, RValue Src);
85
86  void EmitStdInitializerList(llvm::Value *DestPtr, InitListExpr *InitList);
87  void EmitArrayInit(llvm::Value *DestPtr, llvm::ArrayType *AType,
88                     QualType elementType, InitListExpr *E);
89
90  AggValueSlot::NeedsGCBarriers_t needsGC(QualType T) {
91    if (CGF.getLangOpts().getGC() && TypeRequiresGCollection(T))
92      return AggValueSlot::NeedsGCBarriers;
93    return AggValueSlot::DoesNotNeedGCBarriers;
94  }
95
96  bool TypeRequiresGCollection(QualType T);
97
98  //===--------------------------------------------------------------------===//
99  //                            Visitor Methods
100  //===--------------------------------------------------------------------===//
101
102  void VisitStmt(Stmt *S) {
103    CGF.ErrorUnsupported(S, "aggregate expression");
104  }
105  void VisitParenExpr(ParenExpr *PE) { Visit(PE->getSubExpr()); }
106  void VisitGenericSelectionExpr(GenericSelectionExpr *GE) {
107    Visit(GE->getResultExpr());
108  }
109  void VisitUnaryExtension(UnaryOperator *E) { Visit(E->getSubExpr()); }
110  void VisitSubstNonTypeTemplateParmExpr(SubstNonTypeTemplateParmExpr *E) {
111    return Visit(E->getReplacement());
112  }
113
114  // l-values.
115  void VisitDeclRefExpr(DeclRefExpr *E) {
116    // For aggregates, we should always be able to emit the variable
117    // as an l-value unless it's a reference.  This is due to the fact
118    // that we can't actually ever see a normal l2r conversion on an
119    // aggregate in C++, and in C there's no language standard
120    // actively preventing us from listing variables in the captures
121    // list of a block.
122    if (E->getDecl()->getType()->isReferenceType()) {
123      if (CodeGenFunction::ConstantEmission result
124            = CGF.tryEmitAsConstant(E)) {
125        EmitFinalDestCopy(E->getType(), result.getReferenceLValue(CGF, E));
126        return;
127      }
128    }
129
130    EmitAggLoadOfLValue(E);
131  }
132
133  void VisitMemberExpr(MemberExpr *ME) { EmitAggLoadOfLValue(ME); }
134  void VisitUnaryDeref(UnaryOperator *E) { EmitAggLoadOfLValue(E); }
135  void VisitStringLiteral(StringLiteral *E) { EmitAggLoadOfLValue(E); }
136  void VisitCompoundLiteralExpr(CompoundLiteralExpr *E);
137  void VisitArraySubscriptExpr(ArraySubscriptExpr *E) {
138    EmitAggLoadOfLValue(E);
139  }
140  void VisitPredefinedExpr(const PredefinedExpr *E) {
141    EmitAggLoadOfLValue(E);
142  }
143
144  // Operators.
145  void VisitCastExpr(CastExpr *E);
146  void VisitCallExpr(const CallExpr *E);
147  void VisitStmtExpr(const StmtExpr *E);
148  void VisitBinaryOperator(const BinaryOperator *BO);
149  void VisitPointerToDataMemberBinaryOperator(const BinaryOperator *BO);
150  void VisitBinAssign(const BinaryOperator *E);
151  void VisitBinComma(const BinaryOperator *E);
152
153  void VisitObjCMessageExpr(ObjCMessageExpr *E);
154  void VisitObjCIvarRefExpr(ObjCIvarRefExpr *E) {
155    EmitAggLoadOfLValue(E);
156  }
157
158  void VisitAbstractConditionalOperator(const AbstractConditionalOperator *CO);
159  void VisitChooseExpr(const ChooseExpr *CE);
160  void VisitInitListExpr(InitListExpr *E);
161  void VisitImplicitValueInitExpr(ImplicitValueInitExpr *E);
162  void VisitCXXDefaultArgExpr(CXXDefaultArgExpr *DAE) {
163    Visit(DAE->getExpr());
164  }
165  void VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E);
166  void VisitCXXConstructExpr(const CXXConstructExpr *E);
167  void VisitLambdaExpr(LambdaExpr *E);
168  void VisitExprWithCleanups(ExprWithCleanups *E);
169  void VisitCXXScalarValueInitExpr(CXXScalarValueInitExpr *E);
170  void VisitCXXTypeidExpr(CXXTypeidExpr *E) { EmitAggLoadOfLValue(E); }
171  void VisitMaterializeTemporaryExpr(MaterializeTemporaryExpr *E);
172  void VisitOpaqueValueExpr(OpaqueValueExpr *E);
173
174  void VisitPseudoObjectExpr(PseudoObjectExpr *E) {
175    if (E->isGLValue()) {
176      LValue LV = CGF.EmitPseudoObjectLValue(E);
177      return EmitFinalDestCopy(E->getType(), LV);
178    }
179
180    CGF.EmitPseudoObjectRValue(E, EnsureSlot(E->getType()));
181  }
182
183  void VisitVAArgExpr(VAArgExpr *E);
184
185  void EmitInitializationToLValue(Expr *E, LValue Address);
186  void EmitNullInitializationToLValue(LValue Address);
187  //  case Expr::ChooseExprClass:
188  void VisitCXXThrowExpr(const CXXThrowExpr *E) { CGF.EmitCXXThrowExpr(E); }
189  void VisitAtomicExpr(AtomicExpr *E) {
190    CGF.EmitAtomicExpr(E, EnsureSlot(E->getType()).getAddr());
191  }
192};
193}  // end anonymous namespace.
194
195//===----------------------------------------------------------------------===//
196//                                Utilities
197//===----------------------------------------------------------------------===//
198
199/// EmitAggLoadOfLValue - Given an expression with aggregate type that
200/// represents a value lvalue, this method emits the address of the lvalue,
201/// then loads the result into DestPtr.
202void AggExprEmitter::EmitAggLoadOfLValue(const Expr *E) {
203  LValue LV = CGF.EmitLValue(E);
204  EmitFinalDestCopy(E->getType(), LV);
205}
206
207/// \brief True if the given aggregate type requires special GC API calls.
208bool AggExprEmitter::TypeRequiresGCollection(QualType T) {
209  // Only record types have members that might require garbage collection.
210  const RecordType *RecordTy = T->getAs<RecordType>();
211  if (!RecordTy) return false;
212
213  // Don't mess with non-trivial C++ types.
214  RecordDecl *Record = RecordTy->getDecl();
215  if (isa<CXXRecordDecl>(Record) &&
216      (cast<CXXRecordDecl>(Record)->hasNonTrivialCopyConstructor() ||
217       !cast<CXXRecordDecl>(Record)->hasTrivialDestructor()))
218    return false;
219
220  // Check whether the type has an object member.
221  return Record->hasObjectMember();
222}
223
224/// \brief Perform the final move to DestPtr if for some reason
225/// getReturnValueSlot() didn't use it directly.
226///
227/// The idea is that you do something like this:
228///   RValue Result = EmitSomething(..., getReturnValueSlot());
229///   EmitMoveFromReturnSlot(E, Result);
230///
231/// If nothing interferes, this will cause the result to be emitted
232/// directly into the return value slot.  Otherwise, a final move
233/// will be performed.
234void AggExprEmitter::EmitMoveFromReturnSlot(const Expr *E, RValue src) {
235  if (shouldUseDestForReturnSlot()) {
236    // Logically, Dest.getAddr() should equal Src.getAggregateAddr().
237    // The possibility of undef rvalues complicates that a lot,
238    // though, so we can't really assert.
239    return;
240  }
241
242  // Otherwise, copy from there to the destination.
243  assert(Dest.getAddr() != src.getAggregateAddr());
244  std::pair<CharUnits, CharUnits> typeInfo =
245    CGF.getContext().getTypeInfoInChars(E->getType());
246  EmitFinalDestCopy(E->getType(), src, typeInfo.second);
247}
248
249/// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired.
250void AggExprEmitter::EmitFinalDestCopy(QualType type, RValue src,
251                                       CharUnits srcAlign) {
252  assert(src.isAggregate() && "value must be aggregate value!");
253  LValue srcLV = CGF.MakeAddrLValue(src.getAggregateAddr(), type, srcAlign);
254  EmitFinalDestCopy(type, srcLV);
255}
256
257/// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired.
258void AggExprEmitter::EmitFinalDestCopy(QualType type, const LValue &src) {
259  // If Dest is ignored, then we're evaluating an aggregate expression
260  // in a context that doesn't care about the result.  Note that loads
261  // from volatile l-values force the existence of a non-ignored
262  // destination.
263  if (Dest.isIgnored())
264    return;
265
266  AggValueSlot srcAgg =
267    AggValueSlot::forLValue(src, AggValueSlot::IsDestructed,
268                            needsGC(type), AggValueSlot::IsAliased);
269  EmitCopy(type, Dest, srcAgg);
270}
271
272/// Perform a copy from the source into the destination.
273///
274/// \param type - the type of the aggregate being copied; qualifiers are
275///   ignored
276void AggExprEmitter::EmitCopy(QualType type, const AggValueSlot &dest,
277                              const AggValueSlot &src) {
278  if (dest.requiresGCollection()) {
279    CharUnits sz = CGF.getContext().getTypeSizeInChars(type);
280    llvm::Value *size = llvm::ConstantInt::get(CGF.SizeTy, sz.getQuantity());
281    CGF.CGM.getObjCRuntime().EmitGCMemmoveCollectable(CGF,
282                                                      dest.getAddr(),
283                                                      src.getAddr(),
284                                                      size);
285    return;
286  }
287
288  // If the result of the assignment is used, copy the LHS there also.
289  // It's volatile if either side is.  Use the minimum alignment of
290  // the two sides.
291  CGF.EmitAggregateCopy(dest.getAddr(), src.getAddr(), type,
292                        dest.isVolatile() || src.isVolatile(),
293                        std::min(dest.getAlignment(), src.getAlignment()));
294}
295
296static QualType GetStdInitializerListElementType(QualType T) {
297  // Just assume that this is really std::initializer_list.
298  ClassTemplateSpecializationDecl *specialization =
299      cast<ClassTemplateSpecializationDecl>(T->castAs<RecordType>()->getDecl());
300  return specialization->getTemplateArgs()[0].getAsType();
301}
302
303/// \brief Prepare cleanup for the temporary array.
304static void EmitStdInitializerListCleanup(CodeGenFunction &CGF,
305                                          QualType arrayType,
306                                          llvm::Value *addr,
307                                          const InitListExpr *initList) {
308  QualType::DestructionKind dtorKind = arrayType.isDestructedType();
309  if (!dtorKind)
310    return; // Type doesn't need destroying.
311  if (dtorKind != QualType::DK_cxx_destructor) {
312    CGF.ErrorUnsupported(initList, "ObjC ARC type in initializer_list");
313    return;
314  }
315
316  CodeGenFunction::Destroyer *destroyer = CGF.getDestroyer(dtorKind);
317  CGF.pushDestroy(NormalAndEHCleanup, addr, arrayType, destroyer,
318                  /*EHCleanup=*/true);
319}
320
321/// \brief Emit the initializer for a std::initializer_list initialized with a
322/// real initializer list.
323void AggExprEmitter::EmitStdInitializerList(llvm::Value *destPtr,
324                                            InitListExpr *initList) {
325  // We emit an array containing the elements, then have the init list point
326  // at the array.
327  ASTContext &ctx = CGF.getContext();
328  unsigned numInits = initList->getNumInits();
329  QualType element = GetStdInitializerListElementType(initList->getType());
330  llvm::APInt size(ctx.getTypeSize(ctx.getSizeType()), numInits);
331  QualType array = ctx.getConstantArrayType(element, size, ArrayType::Normal,0);
332  llvm::Type *LTy = CGF.ConvertTypeForMem(array);
333  llvm::AllocaInst *alloc = CGF.CreateTempAlloca(LTy);
334  alloc->setAlignment(ctx.getTypeAlignInChars(array).getQuantity());
335  alloc->setName(".initlist.");
336
337  EmitArrayInit(alloc, cast<llvm::ArrayType>(LTy), element, initList);
338
339  // FIXME: The diagnostics are somewhat out of place here.
340  RecordDecl *record = initList->getType()->castAs<RecordType>()->getDecl();
341  RecordDecl::field_iterator field = record->field_begin();
342  if (field == record->field_end()) {
343    CGF.ErrorUnsupported(initList, "weird std::initializer_list");
344    return;
345  }
346
347  QualType elementPtr = ctx.getPointerType(element.withConst());
348
349  // Start pointer.
350  if (!ctx.hasSameType(field->getType(), elementPtr)) {
351    CGF.ErrorUnsupported(initList, "weird std::initializer_list");
352    return;
353  }
354  LValue DestLV = CGF.MakeNaturalAlignAddrLValue(destPtr, initList->getType());
355  LValue start = CGF.EmitLValueForFieldInitialization(DestLV, *field);
356  llvm::Value *arrayStart = Builder.CreateStructGEP(alloc, 0, "arraystart");
357  CGF.EmitStoreThroughLValue(RValue::get(arrayStart), start);
358  ++field;
359
360  if (field == record->field_end()) {
361    CGF.ErrorUnsupported(initList, "weird std::initializer_list");
362    return;
363  }
364  LValue endOrLength = CGF.EmitLValueForFieldInitialization(DestLV, *field);
365  if (ctx.hasSameType(field->getType(), elementPtr)) {
366    // End pointer.
367    llvm::Value *arrayEnd = Builder.CreateStructGEP(alloc,numInits, "arrayend");
368    CGF.EmitStoreThroughLValue(RValue::get(arrayEnd), endOrLength);
369  } else if(ctx.hasSameType(field->getType(), ctx.getSizeType())) {
370    // Length.
371    CGF.EmitStoreThroughLValue(RValue::get(Builder.getInt(size)), endOrLength);
372  } else {
373    CGF.ErrorUnsupported(initList, "weird std::initializer_list");
374    return;
375  }
376
377  if (!Dest.isExternallyDestructed())
378    EmitStdInitializerListCleanup(CGF, array, alloc, initList);
379}
380
381/// \brief Emit initialization of an array from an initializer list.
382void AggExprEmitter::EmitArrayInit(llvm::Value *DestPtr, llvm::ArrayType *AType,
383                                   QualType elementType, InitListExpr *E) {
384  uint64_t NumInitElements = E->getNumInits();
385
386  uint64_t NumArrayElements = AType->getNumElements();
387  assert(NumInitElements <= NumArrayElements);
388
389  // DestPtr is an array*.  Construct an elementType* by drilling
390  // down a level.
391  llvm::Value *zero = llvm::ConstantInt::get(CGF.SizeTy, 0);
392  llvm::Value *indices[] = { zero, zero };
393  llvm::Value *begin =
394    Builder.CreateInBoundsGEP(DestPtr, indices, "arrayinit.begin");
395
396  // Exception safety requires us to destroy all the
397  // already-constructed members if an initializer throws.
398  // For that, we'll need an EH cleanup.
399  QualType::DestructionKind dtorKind = elementType.isDestructedType();
400  llvm::AllocaInst *endOfInit = 0;
401  EHScopeStack::stable_iterator cleanup;
402  llvm::Instruction *cleanupDominator = 0;
403  if (CGF.needsEHCleanup(dtorKind)) {
404    // In principle we could tell the cleanup where we are more
405    // directly, but the control flow can get so varied here that it
406    // would actually be quite complex.  Therefore we go through an
407    // alloca.
408    endOfInit = CGF.CreateTempAlloca(begin->getType(),
409                                     "arrayinit.endOfInit");
410    cleanupDominator = Builder.CreateStore(begin, endOfInit);
411    CGF.pushIrregularPartialArrayCleanup(begin, endOfInit, elementType,
412                                         CGF.getDestroyer(dtorKind));
413    cleanup = CGF.EHStack.stable_begin();
414
415  // Otherwise, remember that we didn't need a cleanup.
416  } else {
417    dtorKind = QualType::DK_none;
418  }
419
420  llvm::Value *one = llvm::ConstantInt::get(CGF.SizeTy, 1);
421
422  // The 'current element to initialize'.  The invariants on this
423  // variable are complicated.  Essentially, after each iteration of
424  // the loop, it points to the last initialized element, except
425  // that it points to the beginning of the array before any
426  // elements have been initialized.
427  llvm::Value *element = begin;
428
429  // Emit the explicit initializers.
430  for (uint64_t i = 0; i != NumInitElements; ++i) {
431    // Advance to the next element.
432    if (i > 0) {
433      element = Builder.CreateInBoundsGEP(element, one, "arrayinit.element");
434
435      // Tell the cleanup that it needs to destroy up to this
436      // element.  TODO: some of these stores can be trivially
437      // observed to be unnecessary.
438      if (endOfInit) Builder.CreateStore(element, endOfInit);
439    }
440
441    // If these are nested std::initializer_list inits, do them directly,
442    // because they are conceptually the same "location".
443    InitListExpr *initList = dyn_cast<InitListExpr>(E->getInit(i));
444    if (initList && initList->initializesStdInitializerList()) {
445      EmitStdInitializerList(element, initList);
446    } else {
447      LValue elementLV = CGF.MakeAddrLValue(element, elementType);
448      EmitInitializationToLValue(E->getInit(i), elementLV);
449    }
450  }
451
452  // Check whether there's a non-trivial array-fill expression.
453  // Note that this will be a CXXConstructExpr even if the element
454  // type is an array (or array of array, etc.) of class type.
455  Expr *filler = E->getArrayFiller();
456  bool hasTrivialFiller = true;
457  if (CXXConstructExpr *cons = dyn_cast_or_null<CXXConstructExpr>(filler)) {
458    assert(cons->getConstructor()->isDefaultConstructor());
459    hasTrivialFiller = cons->getConstructor()->isTrivial();
460  }
461
462  // Any remaining elements need to be zero-initialized, possibly
463  // using the filler expression.  We can skip this if the we're
464  // emitting to zeroed memory.
465  if (NumInitElements != NumArrayElements &&
466      !(Dest.isZeroed() && hasTrivialFiller &&
467        CGF.getTypes().isZeroInitializable(elementType))) {
468
469    // Use an actual loop.  This is basically
470    //   do { *array++ = filler; } while (array != end);
471
472    // Advance to the start of the rest of the array.
473    if (NumInitElements) {
474      element = Builder.CreateInBoundsGEP(element, one, "arrayinit.start");
475      if (endOfInit) Builder.CreateStore(element, endOfInit);
476    }
477
478    // Compute the end of the array.
479    llvm::Value *end = Builder.CreateInBoundsGEP(begin,
480                      llvm::ConstantInt::get(CGF.SizeTy, NumArrayElements),
481                                                 "arrayinit.end");
482
483    llvm::BasicBlock *entryBB = Builder.GetInsertBlock();
484    llvm::BasicBlock *bodyBB = CGF.createBasicBlock("arrayinit.body");
485
486    // Jump into the body.
487    CGF.EmitBlock(bodyBB);
488    llvm::PHINode *currentElement =
489      Builder.CreatePHI(element->getType(), 2, "arrayinit.cur");
490    currentElement->addIncoming(element, entryBB);
491
492    // Emit the actual filler expression.
493    LValue elementLV = CGF.MakeAddrLValue(currentElement, elementType);
494    if (filler)
495      EmitInitializationToLValue(filler, elementLV);
496    else
497      EmitNullInitializationToLValue(elementLV);
498
499    // Move on to the next element.
500    llvm::Value *nextElement =
501      Builder.CreateInBoundsGEP(currentElement, one, "arrayinit.next");
502
503    // Tell the EH cleanup that we finished with the last element.
504    if (endOfInit) Builder.CreateStore(nextElement, endOfInit);
505
506    // Leave the loop if we're done.
507    llvm::Value *done = Builder.CreateICmpEQ(nextElement, end,
508                                             "arrayinit.done");
509    llvm::BasicBlock *endBB = CGF.createBasicBlock("arrayinit.end");
510    Builder.CreateCondBr(done, endBB, bodyBB);
511    currentElement->addIncoming(nextElement, Builder.GetInsertBlock());
512
513    CGF.EmitBlock(endBB);
514  }
515
516  // Leave the partial-array cleanup if we entered one.
517  if (dtorKind) CGF.DeactivateCleanupBlock(cleanup, cleanupDominator);
518}
519
520//===----------------------------------------------------------------------===//
521//                            Visitor Methods
522//===----------------------------------------------------------------------===//
523
524void AggExprEmitter::VisitMaterializeTemporaryExpr(MaterializeTemporaryExpr *E){
525  Visit(E->GetTemporaryExpr());
526}
527
528void AggExprEmitter::VisitOpaqueValueExpr(OpaqueValueExpr *e) {
529  EmitFinalDestCopy(e->getType(), CGF.getOpaqueLValueMapping(e));
530}
531
532void
533AggExprEmitter::VisitCompoundLiteralExpr(CompoundLiteralExpr *E) {
534  if (E->getType().isPODType(CGF.getContext())) {
535    // For a POD type, just emit a load of the lvalue + a copy, because our
536    // compound literal might alias the destination.
537    // FIXME: This is a band-aid; the real problem appears to be in our handling
538    // of assignments, where we store directly into the LHS without checking
539    // whether anything in the RHS aliases.
540    EmitAggLoadOfLValue(E);
541    return;
542  }
543
544  AggValueSlot Slot = EnsureSlot(E->getType());
545  CGF.EmitAggExpr(E->getInitializer(), Slot);
546}
547
548
549void AggExprEmitter::VisitCastExpr(CastExpr *E) {
550  switch (E->getCastKind()) {
551  case CK_Dynamic: {
552    // FIXME: Can this actually happen? We have no test coverage for it.
553    assert(isa<CXXDynamicCastExpr>(E) && "CK_Dynamic without a dynamic_cast?");
554    LValue LV = CGF.EmitCheckedLValue(E->getSubExpr(),
555                                      CodeGenFunction::TCK_Load);
556    // FIXME: Do we also need to handle property references here?
557    if (LV.isSimple())
558      CGF.EmitDynamicCast(LV.getAddress(), cast<CXXDynamicCastExpr>(E));
559    else
560      CGF.CGM.ErrorUnsupported(E, "non-simple lvalue dynamic_cast");
561
562    if (!Dest.isIgnored())
563      CGF.CGM.ErrorUnsupported(E, "lvalue dynamic_cast with a destination");
564    break;
565  }
566
567  case CK_ToUnion: {
568    if (Dest.isIgnored()) break;
569
570    // GCC union extension
571    QualType Ty = E->getSubExpr()->getType();
572    QualType PtrTy = CGF.getContext().getPointerType(Ty);
573    llvm::Value *CastPtr = Builder.CreateBitCast(Dest.getAddr(),
574                                                 CGF.ConvertType(PtrTy));
575    EmitInitializationToLValue(E->getSubExpr(),
576                               CGF.MakeAddrLValue(CastPtr, Ty));
577    break;
578  }
579
580  case CK_DerivedToBase:
581  case CK_BaseToDerived:
582  case CK_UncheckedDerivedToBase: {
583    llvm_unreachable("cannot perform hierarchy conversion in EmitAggExpr: "
584                "should have been unpacked before we got here");
585  }
586
587  case CK_LValueToRValue:
588    // If we're loading from a volatile type, force the destination
589    // into existence.
590    if (E->getSubExpr()->getType().isVolatileQualified()) {
591      EnsureDest(E->getType());
592      return Visit(E->getSubExpr());
593    }
594    // fallthrough
595
596  case CK_NoOp:
597  case CK_AtomicToNonAtomic:
598  case CK_NonAtomicToAtomic:
599  case CK_UserDefinedConversion:
600  case CK_ConstructorConversion:
601    assert(CGF.getContext().hasSameUnqualifiedType(E->getSubExpr()->getType(),
602                                                   E->getType()) &&
603           "Implicit cast types must be compatible");
604    Visit(E->getSubExpr());
605    break;
606
607  case CK_LValueBitCast:
608    llvm_unreachable("should not be emitting lvalue bitcast as rvalue");
609
610  case CK_Dependent:
611  case CK_BitCast:
612  case CK_ArrayToPointerDecay:
613  case CK_FunctionToPointerDecay:
614  case CK_NullToPointer:
615  case CK_NullToMemberPointer:
616  case CK_BaseToDerivedMemberPointer:
617  case CK_DerivedToBaseMemberPointer:
618  case CK_MemberPointerToBoolean:
619  case CK_ReinterpretMemberPointer:
620  case CK_IntegralToPointer:
621  case CK_PointerToIntegral:
622  case CK_PointerToBoolean:
623  case CK_ToVoid:
624  case CK_VectorSplat:
625  case CK_IntegralCast:
626  case CK_IntegralToBoolean:
627  case CK_IntegralToFloating:
628  case CK_FloatingToIntegral:
629  case CK_FloatingToBoolean:
630  case CK_FloatingCast:
631  case CK_CPointerToObjCPointerCast:
632  case CK_BlockPointerToObjCPointerCast:
633  case CK_AnyPointerToBlockPointerCast:
634  case CK_ObjCObjectLValueCast:
635  case CK_FloatingRealToComplex:
636  case CK_FloatingComplexToReal:
637  case CK_FloatingComplexToBoolean:
638  case CK_FloatingComplexCast:
639  case CK_FloatingComplexToIntegralComplex:
640  case CK_IntegralRealToComplex:
641  case CK_IntegralComplexToReal:
642  case CK_IntegralComplexToBoolean:
643  case CK_IntegralComplexCast:
644  case CK_IntegralComplexToFloatingComplex:
645  case CK_ARCProduceObject:
646  case CK_ARCConsumeObject:
647  case CK_ARCReclaimReturnedObject:
648  case CK_ARCExtendBlockObject:
649  case CK_CopyAndAutoreleaseBlockObject:
650  case CK_BuiltinFnToFnPtr:
651  case CK_ZeroToOCLEvent:
652    llvm_unreachable("cast kind invalid for aggregate types");
653  }
654}
655
656void AggExprEmitter::VisitCallExpr(const CallExpr *E) {
657  if (E->getCallReturnType()->isReferenceType()) {
658    EmitAggLoadOfLValue(E);
659    return;
660  }
661
662  RValue RV = CGF.EmitCallExpr(E, getReturnValueSlot());
663  EmitMoveFromReturnSlot(E, RV);
664}
665
666void AggExprEmitter::VisitObjCMessageExpr(ObjCMessageExpr *E) {
667  RValue RV = CGF.EmitObjCMessageExpr(E, getReturnValueSlot());
668  EmitMoveFromReturnSlot(E, RV);
669}
670
671void AggExprEmitter::VisitBinComma(const BinaryOperator *E) {
672  CGF.EmitIgnoredExpr(E->getLHS());
673  Visit(E->getRHS());
674}
675
676void AggExprEmitter::VisitStmtExpr(const StmtExpr *E) {
677  CodeGenFunction::StmtExprEvaluation eval(CGF);
678  CGF.EmitCompoundStmt(*E->getSubStmt(), true, Dest);
679}
680
681void AggExprEmitter::VisitBinaryOperator(const BinaryOperator *E) {
682  if (E->getOpcode() == BO_PtrMemD || E->getOpcode() == BO_PtrMemI)
683    VisitPointerToDataMemberBinaryOperator(E);
684  else
685    CGF.ErrorUnsupported(E, "aggregate binary expression");
686}
687
688void AggExprEmitter::VisitPointerToDataMemberBinaryOperator(
689                                                    const BinaryOperator *E) {
690  LValue LV = CGF.EmitPointerToDataMemberBinaryExpr(E);
691  EmitFinalDestCopy(E->getType(), LV);
692}
693
694/// Is the value of the given expression possibly a reference to or
695/// into a __block variable?
696static bool isBlockVarRef(const Expr *E) {
697  // Make sure we look through parens.
698  E = E->IgnoreParens();
699
700  // Check for a direct reference to a __block variable.
701  if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) {
702    const VarDecl *var = dyn_cast<VarDecl>(DRE->getDecl());
703    return (var && var->hasAttr<BlocksAttr>());
704  }
705
706  // More complicated stuff.
707
708  // Binary operators.
709  if (const BinaryOperator *op = dyn_cast<BinaryOperator>(E)) {
710    // For an assignment or pointer-to-member operation, just care
711    // about the LHS.
712    if (op->isAssignmentOp() || op->isPtrMemOp())
713      return isBlockVarRef(op->getLHS());
714
715    // For a comma, just care about the RHS.
716    if (op->getOpcode() == BO_Comma)
717      return isBlockVarRef(op->getRHS());
718
719    // FIXME: pointer arithmetic?
720    return false;
721
722  // Check both sides of a conditional operator.
723  } else if (const AbstractConditionalOperator *op
724               = dyn_cast<AbstractConditionalOperator>(E)) {
725    return isBlockVarRef(op->getTrueExpr())
726        || isBlockVarRef(op->getFalseExpr());
727
728  // OVEs are required to support BinaryConditionalOperators.
729  } else if (const OpaqueValueExpr *op
730               = dyn_cast<OpaqueValueExpr>(E)) {
731    if (const Expr *src = op->getSourceExpr())
732      return isBlockVarRef(src);
733
734  // Casts are necessary to get things like (*(int*)&var) = foo().
735  // We don't really care about the kind of cast here, except
736  // we don't want to look through l2r casts, because it's okay
737  // to get the *value* in a __block variable.
738  } else if (const CastExpr *cast = dyn_cast<CastExpr>(E)) {
739    if (cast->getCastKind() == CK_LValueToRValue)
740      return false;
741    return isBlockVarRef(cast->getSubExpr());
742
743  // Handle unary operators.  Again, just aggressively look through
744  // it, ignoring the operation.
745  } else if (const UnaryOperator *uop = dyn_cast<UnaryOperator>(E)) {
746    return isBlockVarRef(uop->getSubExpr());
747
748  // Look into the base of a field access.
749  } else if (const MemberExpr *mem = dyn_cast<MemberExpr>(E)) {
750    return isBlockVarRef(mem->getBase());
751
752  // Look into the base of a subscript.
753  } else if (const ArraySubscriptExpr *sub = dyn_cast<ArraySubscriptExpr>(E)) {
754    return isBlockVarRef(sub->getBase());
755  }
756
757  return false;
758}
759
760void AggExprEmitter::VisitBinAssign(const BinaryOperator *E) {
761  // For an assignment to work, the value on the right has
762  // to be compatible with the value on the left.
763  assert(CGF.getContext().hasSameUnqualifiedType(E->getLHS()->getType(),
764                                                 E->getRHS()->getType())
765         && "Invalid assignment");
766
767  // If the LHS might be a __block variable, and the RHS can
768  // potentially cause a block copy, we need to evaluate the RHS first
769  // so that the assignment goes the right place.
770  // This is pretty semantically fragile.
771  if (isBlockVarRef(E->getLHS()) &&
772      E->getRHS()->HasSideEffects(CGF.getContext())) {
773    // Ensure that we have a destination, and evaluate the RHS into that.
774    EnsureDest(E->getRHS()->getType());
775    Visit(E->getRHS());
776
777    // Now emit the LHS and copy into it.
778    LValue LHS = CGF.EmitCheckedLValue(E->getLHS(), CodeGenFunction::TCK_Store);
779
780    EmitCopy(E->getLHS()->getType(),
781             AggValueSlot::forLValue(LHS, AggValueSlot::IsDestructed,
782                                     needsGC(E->getLHS()->getType()),
783                                     AggValueSlot::IsAliased),
784             Dest);
785    return;
786  }
787
788  LValue LHS = CGF.EmitLValue(E->getLHS());
789
790  // Codegen the RHS so that it stores directly into the LHS.
791  AggValueSlot LHSSlot =
792    AggValueSlot::forLValue(LHS, AggValueSlot::IsDestructed,
793                            needsGC(E->getLHS()->getType()),
794                            AggValueSlot::IsAliased);
795  CGF.EmitAggExpr(E->getRHS(), LHSSlot);
796
797  // Copy into the destination if the assignment isn't ignored.
798  EmitFinalDestCopy(E->getType(), LHS);
799}
800
801void AggExprEmitter::
802VisitAbstractConditionalOperator(const AbstractConditionalOperator *E) {
803  llvm::BasicBlock *LHSBlock = CGF.createBasicBlock("cond.true");
804  llvm::BasicBlock *RHSBlock = CGF.createBasicBlock("cond.false");
805  llvm::BasicBlock *ContBlock = CGF.createBasicBlock("cond.end");
806
807  // Bind the common expression if necessary.
808  CodeGenFunction::OpaqueValueMapping binding(CGF, E);
809
810  CodeGenFunction::ConditionalEvaluation eval(CGF);
811  CGF.EmitBranchOnBoolExpr(E->getCond(), LHSBlock, RHSBlock);
812
813  // Save whether the destination's lifetime is externally managed.
814  bool isExternallyDestructed = Dest.isExternallyDestructed();
815
816  eval.begin(CGF);
817  CGF.EmitBlock(LHSBlock);
818  Visit(E->getTrueExpr());
819  eval.end(CGF);
820
821  assert(CGF.HaveInsertPoint() && "expression evaluation ended with no IP!");
822  CGF.Builder.CreateBr(ContBlock);
823
824  // If the result of an agg expression is unused, then the emission
825  // of the LHS might need to create a destination slot.  That's fine
826  // with us, and we can safely emit the RHS into the same slot, but
827  // we shouldn't claim that it's already being destructed.
828  Dest.setExternallyDestructed(isExternallyDestructed);
829
830  eval.begin(CGF);
831  CGF.EmitBlock(RHSBlock);
832  Visit(E->getFalseExpr());
833  eval.end(CGF);
834
835  CGF.EmitBlock(ContBlock);
836}
837
838void AggExprEmitter::VisitChooseExpr(const ChooseExpr *CE) {
839  Visit(CE->getChosenSubExpr(CGF.getContext()));
840}
841
842void AggExprEmitter::VisitVAArgExpr(VAArgExpr *VE) {
843  llvm::Value *ArgValue = CGF.EmitVAListRef(VE->getSubExpr());
844  llvm::Value *ArgPtr = CGF.EmitVAArg(ArgValue, VE->getType());
845
846  if (!ArgPtr) {
847    CGF.ErrorUnsupported(VE, "aggregate va_arg expression");
848    return;
849  }
850
851  EmitFinalDestCopy(VE->getType(), CGF.MakeAddrLValue(ArgPtr, VE->getType()));
852}
853
854void AggExprEmitter::VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E) {
855  // Ensure that we have a slot, but if we already do, remember
856  // whether it was externally destructed.
857  bool wasExternallyDestructed = Dest.isExternallyDestructed();
858  EnsureDest(E->getType());
859
860  // We're going to push a destructor if there isn't already one.
861  Dest.setExternallyDestructed();
862
863  Visit(E->getSubExpr());
864
865  // Push that destructor we promised.
866  if (!wasExternallyDestructed)
867    CGF.EmitCXXTemporary(E->getTemporary(), E->getType(), Dest.getAddr());
868}
869
870void
871AggExprEmitter::VisitCXXConstructExpr(const CXXConstructExpr *E) {
872  AggValueSlot Slot = EnsureSlot(E->getType());
873  CGF.EmitCXXConstructExpr(E, Slot);
874}
875
876void
877AggExprEmitter::VisitLambdaExpr(LambdaExpr *E) {
878  AggValueSlot Slot = EnsureSlot(E->getType());
879  CGF.EmitLambdaExpr(E, Slot);
880}
881
882void AggExprEmitter::VisitExprWithCleanups(ExprWithCleanups *E) {
883  CGF.enterFullExpression(E);
884  CodeGenFunction::RunCleanupsScope cleanups(CGF);
885  Visit(E->getSubExpr());
886}
887
888void AggExprEmitter::VisitCXXScalarValueInitExpr(CXXScalarValueInitExpr *E) {
889  QualType T = E->getType();
890  AggValueSlot Slot = EnsureSlot(T);
891  EmitNullInitializationToLValue(CGF.MakeAddrLValue(Slot.getAddr(), T));
892}
893
894void AggExprEmitter::VisitImplicitValueInitExpr(ImplicitValueInitExpr *E) {
895  QualType T = E->getType();
896  AggValueSlot Slot = EnsureSlot(T);
897  EmitNullInitializationToLValue(CGF.MakeAddrLValue(Slot.getAddr(), T));
898}
899
900/// isSimpleZero - If emitting this value will obviously just cause a store of
901/// zero to memory, return true.  This can return false if uncertain, so it just
902/// handles simple cases.
903static bool isSimpleZero(const Expr *E, CodeGenFunction &CGF) {
904  E = E->IgnoreParens();
905
906  // 0
907  if (const IntegerLiteral *IL = dyn_cast<IntegerLiteral>(E))
908    return IL->getValue() == 0;
909  // +0.0
910  if (const FloatingLiteral *FL = dyn_cast<FloatingLiteral>(E))
911    return FL->getValue().isPosZero();
912  // int()
913  if ((isa<ImplicitValueInitExpr>(E) || isa<CXXScalarValueInitExpr>(E)) &&
914      CGF.getTypes().isZeroInitializable(E->getType()))
915    return true;
916  // (int*)0 - Null pointer expressions.
917  if (const CastExpr *ICE = dyn_cast<CastExpr>(E))
918    return ICE->getCastKind() == CK_NullToPointer;
919  // '\0'
920  if (const CharacterLiteral *CL = dyn_cast<CharacterLiteral>(E))
921    return CL->getValue() == 0;
922
923  // Otherwise, hard case: conservatively return false.
924  return false;
925}
926
927
928void
929AggExprEmitter::EmitInitializationToLValue(Expr* E, LValue LV) {
930  QualType type = LV.getType();
931  // FIXME: Ignore result?
932  // FIXME: Are initializers affected by volatile?
933  if (Dest.isZeroed() && isSimpleZero(E, CGF)) {
934    // Storing "i32 0" to a zero'd memory location is a noop.
935  } else if (isa<ImplicitValueInitExpr>(E) || isa<CXXScalarValueInitExpr>(E)) {
936    EmitNullInitializationToLValue(LV);
937  } else if (type->isReferenceType()) {
938    RValue RV = CGF.EmitReferenceBindingToExpr(E, /*InitializedDecl=*/0);
939    CGF.EmitStoreThroughLValue(RV, LV);
940  } else if (type->isAnyComplexType()) {
941    CGF.EmitComplexExprIntoAddr(E, LV.getAddress(), false);
942  } else if (CGF.hasAggregateLLVMType(type)) {
943    CGF.EmitAggExpr(E, AggValueSlot::forLValue(LV,
944                                               AggValueSlot::IsDestructed,
945                                      AggValueSlot::DoesNotNeedGCBarriers,
946                                               AggValueSlot::IsNotAliased,
947                                               Dest.isZeroed()));
948  } else if (LV.isSimple()) {
949    CGF.EmitScalarInit(E, /*D=*/0, LV, /*Captured=*/false);
950  } else {
951    CGF.EmitStoreThroughLValue(RValue::get(CGF.EmitScalarExpr(E)), LV);
952  }
953}
954
955void AggExprEmitter::EmitNullInitializationToLValue(LValue lv) {
956  QualType type = lv.getType();
957
958  // If the destination slot is already zeroed out before the aggregate is
959  // copied into it, we don't have to emit any zeros here.
960  if (Dest.isZeroed() && CGF.getTypes().isZeroInitializable(type))
961    return;
962
963  if (!CGF.hasAggregateLLVMType(type)) {
964    // For non-aggregates, we can store the appropriate null constant.
965    llvm::Value *null = CGF.CGM.EmitNullConstant(type);
966    // Note that the following is not equivalent to
967    // EmitStoreThroughBitfieldLValue for ARC types.
968    if (lv.isBitField()) {
969      CGF.EmitStoreThroughBitfieldLValue(RValue::get(null), lv);
970    } else {
971      assert(lv.isSimple());
972      CGF.EmitStoreOfScalar(null, lv, /* isInitialization */ true);
973    }
974  } else {
975    // There's a potential optimization opportunity in combining
976    // memsets; that would be easy for arrays, but relatively
977    // difficult for structures with the current code.
978    CGF.EmitNullInitialization(lv.getAddress(), lv.getType());
979  }
980}
981
982void AggExprEmitter::VisitInitListExpr(InitListExpr *E) {
983#if 0
984  // FIXME: Assess perf here?  Figure out what cases are worth optimizing here
985  // (Length of globals? Chunks of zeroed-out space?).
986  //
987  // If we can, prefer a copy from a global; this is a lot less code for long
988  // globals, and it's easier for the current optimizers to analyze.
989  if (llvm::Constant* C = CGF.CGM.EmitConstantExpr(E, E->getType(), &CGF)) {
990    llvm::GlobalVariable* GV =
991    new llvm::GlobalVariable(CGF.CGM.getModule(), C->getType(), true,
992                             llvm::GlobalValue::InternalLinkage, C, "");
993    EmitFinalDestCopy(E->getType(), CGF.MakeAddrLValue(GV, E->getType()));
994    return;
995  }
996#endif
997  if (E->hadArrayRangeDesignator())
998    CGF.ErrorUnsupported(E, "GNU array range designator extension");
999
1000  if (E->initializesStdInitializerList()) {
1001    EmitStdInitializerList(Dest.getAddr(), E);
1002    return;
1003  }
1004
1005  AggValueSlot Dest = EnsureSlot(E->getType());
1006  LValue DestLV = CGF.MakeAddrLValue(Dest.getAddr(), E->getType(),
1007                                     Dest.getAlignment());
1008
1009  // Handle initialization of an array.
1010  if (E->getType()->isArrayType()) {
1011    if (E->isStringLiteralInit())
1012      return Visit(E->getInit(0));
1013
1014    QualType elementType =
1015        CGF.getContext().getAsArrayType(E->getType())->getElementType();
1016
1017    llvm::PointerType *APType =
1018      cast<llvm::PointerType>(Dest.getAddr()->getType());
1019    llvm::ArrayType *AType =
1020      cast<llvm::ArrayType>(APType->getElementType());
1021
1022    EmitArrayInit(Dest.getAddr(), AType, elementType, E);
1023    return;
1024  }
1025
1026  assert(E->getType()->isRecordType() && "Only support structs/unions here!");
1027
1028  // Do struct initialization; this code just sets each individual member
1029  // to the approprate value.  This makes bitfield support automatic;
1030  // the disadvantage is that the generated code is more difficult for
1031  // the optimizer, especially with bitfields.
1032  unsigned NumInitElements = E->getNumInits();
1033  RecordDecl *record = E->getType()->castAs<RecordType>()->getDecl();
1034
1035  if (record->isUnion()) {
1036    // Only initialize one field of a union. The field itself is
1037    // specified by the initializer list.
1038    if (!E->getInitializedFieldInUnion()) {
1039      // Empty union; we have nothing to do.
1040
1041#ifndef NDEBUG
1042      // Make sure that it's really an empty and not a failure of
1043      // semantic analysis.
1044      for (RecordDecl::field_iterator Field = record->field_begin(),
1045                                   FieldEnd = record->field_end();
1046           Field != FieldEnd; ++Field)
1047        assert(Field->isUnnamedBitfield() && "Only unnamed bitfields allowed");
1048#endif
1049      return;
1050    }
1051
1052    // FIXME: volatility
1053    FieldDecl *Field = E->getInitializedFieldInUnion();
1054
1055    LValue FieldLoc = CGF.EmitLValueForFieldInitialization(DestLV, Field);
1056    if (NumInitElements) {
1057      // Store the initializer into the field
1058      EmitInitializationToLValue(E->getInit(0), FieldLoc);
1059    } else {
1060      // Default-initialize to null.
1061      EmitNullInitializationToLValue(FieldLoc);
1062    }
1063
1064    return;
1065  }
1066
1067  // We'll need to enter cleanup scopes in case any of the member
1068  // initializers throw an exception.
1069  SmallVector<EHScopeStack::stable_iterator, 16> cleanups;
1070  llvm::Instruction *cleanupDominator = 0;
1071
1072  // Here we iterate over the fields; this makes it simpler to both
1073  // default-initialize fields and skip over unnamed fields.
1074  unsigned curInitIndex = 0;
1075  for (RecordDecl::field_iterator field = record->field_begin(),
1076                               fieldEnd = record->field_end();
1077       field != fieldEnd; ++field) {
1078    // We're done once we hit the flexible array member.
1079    if (field->getType()->isIncompleteArrayType())
1080      break;
1081
1082    // Always skip anonymous bitfields.
1083    if (field->isUnnamedBitfield())
1084      continue;
1085
1086    // We're done if we reach the end of the explicit initializers, we
1087    // have a zeroed object, and the rest of the fields are
1088    // zero-initializable.
1089    if (curInitIndex == NumInitElements && Dest.isZeroed() &&
1090        CGF.getTypes().isZeroInitializable(E->getType()))
1091      break;
1092
1093
1094    LValue LV = CGF.EmitLValueForFieldInitialization(DestLV, *field);
1095    // We never generate write-barries for initialized fields.
1096    LV.setNonGC(true);
1097
1098    if (curInitIndex < NumInitElements) {
1099      // Store the initializer into the field.
1100      EmitInitializationToLValue(E->getInit(curInitIndex++), LV);
1101    } else {
1102      // We're out of initalizers; default-initialize to null
1103      EmitNullInitializationToLValue(LV);
1104    }
1105
1106    // Push a destructor if necessary.
1107    // FIXME: if we have an array of structures, all explicitly
1108    // initialized, we can end up pushing a linear number of cleanups.
1109    bool pushedCleanup = false;
1110    if (QualType::DestructionKind dtorKind
1111          = field->getType().isDestructedType()) {
1112      assert(LV.isSimple());
1113      if (CGF.needsEHCleanup(dtorKind)) {
1114        if (!cleanupDominator)
1115          cleanupDominator = CGF.Builder.CreateUnreachable(); // placeholder
1116
1117        CGF.pushDestroy(EHCleanup, LV.getAddress(), field->getType(),
1118                        CGF.getDestroyer(dtorKind), false);
1119        cleanups.push_back(CGF.EHStack.stable_begin());
1120        pushedCleanup = true;
1121      }
1122    }
1123
1124    // If the GEP didn't get used because of a dead zero init or something
1125    // else, clean it up for -O0 builds and general tidiness.
1126    if (!pushedCleanup && LV.isSimple())
1127      if (llvm::GetElementPtrInst *GEP =
1128            dyn_cast<llvm::GetElementPtrInst>(LV.getAddress()))
1129        if (GEP->use_empty())
1130          GEP->eraseFromParent();
1131  }
1132
1133  // Deactivate all the partial cleanups in reverse order, which
1134  // generally means popping them.
1135  for (unsigned i = cleanups.size(); i != 0; --i)
1136    CGF.DeactivateCleanupBlock(cleanups[i-1], cleanupDominator);
1137
1138  // Destroy the placeholder if we made one.
1139  if (cleanupDominator)
1140    cleanupDominator->eraseFromParent();
1141}
1142
1143//===----------------------------------------------------------------------===//
1144//                        Entry Points into this File
1145//===----------------------------------------------------------------------===//
1146
1147/// GetNumNonZeroBytesInInit - Get an approximate count of the number of
1148/// non-zero bytes that will be stored when outputting the initializer for the
1149/// specified initializer expression.
1150static CharUnits GetNumNonZeroBytesInInit(const Expr *E, CodeGenFunction &CGF) {
1151  E = E->IgnoreParens();
1152
1153  // 0 and 0.0 won't require any non-zero stores!
1154  if (isSimpleZero(E, CGF)) return CharUnits::Zero();
1155
1156  // If this is an initlist expr, sum up the size of sizes of the (present)
1157  // elements.  If this is something weird, assume the whole thing is non-zero.
1158  const InitListExpr *ILE = dyn_cast<InitListExpr>(E);
1159  if (ILE == 0 || !CGF.getTypes().isZeroInitializable(ILE->getType()))
1160    return CGF.getContext().getTypeSizeInChars(E->getType());
1161
1162  // InitListExprs for structs have to be handled carefully.  If there are
1163  // reference members, we need to consider the size of the reference, not the
1164  // referencee.  InitListExprs for unions and arrays can't have references.
1165  if (const RecordType *RT = E->getType()->getAs<RecordType>()) {
1166    if (!RT->isUnionType()) {
1167      RecordDecl *SD = E->getType()->getAs<RecordType>()->getDecl();
1168      CharUnits NumNonZeroBytes = CharUnits::Zero();
1169
1170      unsigned ILEElement = 0;
1171      for (RecordDecl::field_iterator Field = SD->field_begin(),
1172           FieldEnd = SD->field_end(); Field != FieldEnd; ++Field) {
1173        // We're done once we hit the flexible array member or run out of
1174        // InitListExpr elements.
1175        if (Field->getType()->isIncompleteArrayType() ||
1176            ILEElement == ILE->getNumInits())
1177          break;
1178        if (Field->isUnnamedBitfield())
1179          continue;
1180
1181        const Expr *E = ILE->getInit(ILEElement++);
1182
1183        // Reference values are always non-null and have the width of a pointer.
1184        if (Field->getType()->isReferenceType())
1185          NumNonZeroBytes += CGF.getContext().toCharUnitsFromBits(
1186              CGF.getContext().getTargetInfo().getPointerWidth(0));
1187        else
1188          NumNonZeroBytes += GetNumNonZeroBytesInInit(E, CGF);
1189      }
1190
1191      return NumNonZeroBytes;
1192    }
1193  }
1194
1195
1196  CharUnits NumNonZeroBytes = CharUnits::Zero();
1197  for (unsigned i = 0, e = ILE->getNumInits(); i != e; ++i)
1198    NumNonZeroBytes += GetNumNonZeroBytesInInit(ILE->getInit(i), CGF);
1199  return NumNonZeroBytes;
1200}
1201
1202/// CheckAggExprForMemSetUse - If the initializer is large and has a lot of
1203/// zeros in it, emit a memset and avoid storing the individual zeros.
1204///
1205static void CheckAggExprForMemSetUse(AggValueSlot &Slot, const Expr *E,
1206                                     CodeGenFunction &CGF) {
1207  // If the slot is already known to be zeroed, nothing to do.  Don't mess with
1208  // volatile stores.
1209  if (Slot.isZeroed() || Slot.isVolatile() || Slot.getAddr() == 0) return;
1210
1211  // C++ objects with a user-declared constructor don't need zero'ing.
1212  if (CGF.getLangOpts().CPlusPlus)
1213    if (const RecordType *RT = CGF.getContext()
1214                       .getBaseElementType(E->getType())->getAs<RecordType>()) {
1215      const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
1216      if (RD->hasUserDeclaredConstructor())
1217        return;
1218    }
1219
1220  // If the type is 16-bytes or smaller, prefer individual stores over memset.
1221  std::pair<CharUnits, CharUnits> TypeInfo =
1222    CGF.getContext().getTypeInfoInChars(E->getType());
1223  if (TypeInfo.first <= CharUnits::fromQuantity(16))
1224    return;
1225
1226  // Check to see if over 3/4 of the initializer are known to be zero.  If so,
1227  // we prefer to emit memset + individual stores for the rest.
1228  CharUnits NumNonZeroBytes = GetNumNonZeroBytesInInit(E, CGF);
1229  if (NumNonZeroBytes*4 > TypeInfo.first)
1230    return;
1231
1232  // Okay, it seems like a good idea to use an initial memset, emit the call.
1233  llvm::Constant *SizeVal = CGF.Builder.getInt64(TypeInfo.first.getQuantity());
1234  CharUnits Align = TypeInfo.second;
1235
1236  llvm::Value *Loc = Slot.getAddr();
1237
1238  Loc = CGF.Builder.CreateBitCast(Loc, CGF.Int8PtrTy);
1239  CGF.Builder.CreateMemSet(Loc, CGF.Builder.getInt8(0), SizeVal,
1240                           Align.getQuantity(), false);
1241
1242  // Tell the AggExprEmitter that the slot is known zero.
1243  Slot.setZeroed();
1244}
1245
1246
1247
1248
1249/// EmitAggExpr - Emit the computation of the specified expression of aggregate
1250/// type.  The result is computed into DestPtr.  Note that if DestPtr is null,
1251/// the value of the aggregate expression is not needed.  If VolatileDest is
1252/// true, DestPtr cannot be 0.
1253void CodeGenFunction::EmitAggExpr(const Expr *E, AggValueSlot Slot) {
1254  assert(E && hasAggregateLLVMType(E->getType()) &&
1255         "Invalid aggregate expression to emit");
1256  assert((Slot.getAddr() != 0 || Slot.isIgnored()) &&
1257         "slot has bits but no address");
1258
1259  // Optimize the slot if possible.
1260  CheckAggExprForMemSetUse(Slot, E, *this);
1261
1262  AggExprEmitter(*this, Slot).Visit(const_cast<Expr*>(E));
1263}
1264
1265LValue CodeGenFunction::EmitAggExprToLValue(const Expr *E) {
1266  assert(hasAggregateLLVMType(E->getType()) && "Invalid argument!");
1267  llvm::Value *Temp = CreateMemTemp(E->getType());
1268  LValue LV = MakeAddrLValue(Temp, E->getType());
1269  EmitAggExpr(E, AggValueSlot::forLValue(LV, AggValueSlot::IsNotDestructed,
1270                                         AggValueSlot::DoesNotNeedGCBarriers,
1271                                         AggValueSlot::IsNotAliased));
1272  return LV;
1273}
1274
1275void CodeGenFunction::EmitAggregateCopy(llvm::Value *DestPtr,
1276                                        llvm::Value *SrcPtr, QualType Ty,
1277                                        bool isVolatile,
1278                                        CharUnits alignment,
1279                                        bool isAssignment) {
1280  assert(!Ty->isAnyComplexType() && "Shouldn't happen for complex");
1281
1282  if (getLangOpts().CPlusPlus) {
1283    if (const RecordType *RT = Ty->getAs<RecordType>()) {
1284      CXXRecordDecl *Record = cast<CXXRecordDecl>(RT->getDecl());
1285      assert((Record->hasTrivialCopyConstructor() ||
1286              Record->hasTrivialCopyAssignment() ||
1287              Record->hasTrivialMoveConstructor() ||
1288              Record->hasTrivialMoveAssignment()) &&
1289             "Trying to aggregate-copy a type without a trivial copy/move "
1290             "constructor or assignment operator");
1291      // Ignore empty classes in C++.
1292      if (Record->isEmpty())
1293        return;
1294    }
1295  }
1296
1297  // Aggregate assignment turns into llvm.memcpy.  This is almost valid per
1298  // C99 6.5.16.1p3, which states "If the value being stored in an object is
1299  // read from another object that overlaps in anyway the storage of the first
1300  // object, then the overlap shall be exact and the two objects shall have
1301  // qualified or unqualified versions of a compatible type."
1302  //
1303  // memcpy is not defined if the source and destination pointers are exactly
1304  // equal, but other compilers do this optimization, and almost every memcpy
1305  // implementation handles this case safely.  If there is a libc that does not
1306  // safely handle this, we can add a target hook.
1307
1308  // Get data size and alignment info for this aggregate. If this is an
1309  // assignment don't copy the tail padding. Otherwise copying it is fine.
1310  std::pair<CharUnits, CharUnits> TypeInfo;
1311  if (isAssignment)
1312    TypeInfo = getContext().getTypeInfoDataSizeInChars(Ty);
1313  else
1314    TypeInfo = getContext().getTypeInfoInChars(Ty);
1315
1316  if (alignment.isZero())
1317    alignment = TypeInfo.second;
1318
1319  // FIXME: Handle variable sized types.
1320
1321  // FIXME: If we have a volatile struct, the optimizer can remove what might
1322  // appear to be `extra' memory ops:
1323  //
1324  // volatile struct { int i; } a, b;
1325  //
1326  // int main() {
1327  //   a = b;
1328  //   a = b;
1329  // }
1330  //
1331  // we need to use a different call here.  We use isVolatile to indicate when
1332  // either the source or the destination is volatile.
1333
1334  llvm::PointerType *DPT = cast<llvm::PointerType>(DestPtr->getType());
1335  llvm::Type *DBP =
1336    llvm::Type::getInt8PtrTy(getLLVMContext(), DPT->getAddressSpace());
1337  DestPtr = Builder.CreateBitCast(DestPtr, DBP);
1338
1339  llvm::PointerType *SPT = cast<llvm::PointerType>(SrcPtr->getType());
1340  llvm::Type *SBP =
1341    llvm::Type::getInt8PtrTy(getLLVMContext(), SPT->getAddressSpace());
1342  SrcPtr = Builder.CreateBitCast(SrcPtr, SBP);
1343
1344  // Don't do any of the memmove_collectable tests if GC isn't set.
1345  if (CGM.getLangOpts().getGC() == LangOptions::NonGC) {
1346    // fall through
1347  } else if (const RecordType *RecordTy = Ty->getAs<RecordType>()) {
1348    RecordDecl *Record = RecordTy->getDecl();
1349    if (Record->hasObjectMember()) {
1350      CharUnits size = TypeInfo.first;
1351      llvm::Type *SizeTy = ConvertType(getContext().getSizeType());
1352      llvm::Value *SizeVal = llvm::ConstantInt::get(SizeTy, size.getQuantity());
1353      CGM.getObjCRuntime().EmitGCMemmoveCollectable(*this, DestPtr, SrcPtr,
1354                                                    SizeVal);
1355      return;
1356    }
1357  } else if (Ty->isArrayType()) {
1358    QualType BaseType = getContext().getBaseElementType(Ty);
1359    if (const RecordType *RecordTy = BaseType->getAs<RecordType>()) {
1360      if (RecordTy->getDecl()->hasObjectMember()) {
1361        CharUnits size = TypeInfo.first;
1362        llvm::Type *SizeTy = ConvertType(getContext().getSizeType());
1363        llvm::Value *SizeVal =
1364          llvm::ConstantInt::get(SizeTy, size.getQuantity());
1365        CGM.getObjCRuntime().EmitGCMemmoveCollectable(*this, DestPtr, SrcPtr,
1366                                                      SizeVal);
1367        return;
1368      }
1369    }
1370  }
1371
1372  // Determine the metadata to describe the position of any padding in this
1373  // memcpy, as well as the TBAA tags for the members of the struct, in case
1374  // the optimizer wishes to expand it in to scalar memory operations.
1375  llvm::MDNode *TBAAStructTag = CGM.getTBAAStructInfo(Ty);
1376
1377  Builder.CreateMemCpy(DestPtr, SrcPtr,
1378                       llvm::ConstantInt::get(IntPtrTy,
1379                                              TypeInfo.first.getQuantity()),
1380                       alignment.getQuantity(), isVolatile,
1381                       /*TBAATag=*/0, TBAAStructTag);
1382}
1383
1384void CodeGenFunction::MaybeEmitStdInitializerListCleanup(llvm::Value *loc,
1385                                                         const Expr *init) {
1386  const ExprWithCleanups *cleanups = dyn_cast<ExprWithCleanups>(init);
1387  if (cleanups)
1388    init = cleanups->getSubExpr();
1389
1390  if (isa<InitListExpr>(init) &&
1391      cast<InitListExpr>(init)->initializesStdInitializerList()) {
1392    // We initialized this std::initializer_list with an initializer list.
1393    // A backing array was created. Push a cleanup for it.
1394    EmitStdInitializerListCleanup(loc, cast<InitListExpr>(init));
1395  }
1396}
1397
1398static void EmitRecursiveStdInitializerListCleanup(CodeGenFunction &CGF,
1399                                                   llvm::Value *arrayStart,
1400                                                   const InitListExpr *init) {
1401  // Check if there are any recursive cleanups to do, i.e. if we have
1402  //   std::initializer_list<std::initializer_list<obj>> list = {{obj()}};
1403  // then we need to destroy the inner array as well.
1404  for (unsigned i = 0, e = init->getNumInits(); i != e; ++i) {
1405    const InitListExpr *subInit = dyn_cast<InitListExpr>(init->getInit(i));
1406    if (!subInit || !subInit->initializesStdInitializerList())
1407      continue;
1408
1409    // This one needs to be destroyed. Get the address of the std::init_list.
1410    llvm::Value *offset = llvm::ConstantInt::get(CGF.SizeTy, i);
1411    llvm::Value *loc = CGF.Builder.CreateInBoundsGEP(arrayStart, offset,
1412                                                 "std.initlist");
1413    CGF.EmitStdInitializerListCleanup(loc, subInit);
1414  }
1415}
1416
1417void CodeGenFunction::EmitStdInitializerListCleanup(llvm::Value *loc,
1418                                                    const InitListExpr *init) {
1419  ASTContext &ctx = getContext();
1420  QualType element = GetStdInitializerListElementType(init->getType());
1421  unsigned numInits = init->getNumInits();
1422  llvm::APInt size(ctx.getTypeSize(ctx.getSizeType()), numInits);
1423  QualType array =ctx.getConstantArrayType(element, size, ArrayType::Normal, 0);
1424  QualType arrayPtr = ctx.getPointerType(array);
1425  llvm::Type *arrayPtrType = ConvertType(arrayPtr);
1426
1427  // lvalue is the location of a std::initializer_list, which as its first
1428  // element has a pointer to the array we want to destroy.
1429  llvm::Value *startPointer = Builder.CreateStructGEP(loc, 0, "startPointer");
1430  llvm::Value *startAddress = Builder.CreateLoad(startPointer, "startAddress");
1431
1432  ::EmitRecursiveStdInitializerListCleanup(*this, startAddress, init);
1433
1434  llvm::Value *arrayAddress =
1435      Builder.CreateBitCast(startAddress, arrayPtrType, "arrayAddress");
1436  ::EmitStdInitializerListCleanup(*this, array, arrayAddress, init);
1437}
1438