CGExprAgg.cpp revision d97927d69b277120f8d403580c44acd84907d7b4 
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  AggValueSlot Dest;
36  bool IgnoreResult;
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
59public:
60  AggExprEmitter(CodeGenFunction &cgf, AggValueSlot Dest,
61                 bool ignore)
62    : CGF(cgf), Builder(CGF.Builder), Dest(Dest),
63      IgnoreResult(ignore) {
64  }
65
66  //===--------------------------------------------------------------------===//
67  //                               Utilities
68  //===--------------------------------------------------------------------===//
69
70  /// EmitAggLoadOfLValue - Given an expression with aggregate type that
71  /// represents a value lvalue, this method emits the address of the lvalue,
72  /// then loads the result into DestPtr.
73  void EmitAggLoadOfLValue(const Expr *E);
74
75  /// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired.
76  void EmitFinalDestCopy(const Expr *E, LValue Src, bool Ignore = false);
77  void EmitFinalDestCopy(const Expr *E, RValue Src, bool Ignore = false,
78                         unsigned Alignment = 0);
79
80  void EmitMoveFromReturnSlot(const Expr *E, RValue Src);
81
82  AggValueSlot::NeedsGCBarriers_t needsGC(QualType T) {
83    if (CGF.getLangOptions().getGC() && TypeRequiresGCollection(T))
84      return AggValueSlot::NeedsGCBarriers;
85    return AggValueSlot::DoesNotNeedGCBarriers;
86  }
87
88  bool TypeRequiresGCollection(QualType T);
89
90  //===--------------------------------------------------------------------===//
91  //                            Visitor Methods
92  //===--------------------------------------------------------------------===//
93
94  void VisitStmt(Stmt *S) {
95    CGF.ErrorUnsupported(S, "aggregate expression");
96  }
97  void VisitParenExpr(ParenExpr *PE) { Visit(PE->getSubExpr()); }
98  void VisitGenericSelectionExpr(GenericSelectionExpr *GE) {
99    Visit(GE->getResultExpr());
100  }
101  void VisitUnaryExtension(UnaryOperator *E) { Visit(E->getSubExpr()); }
102  void VisitSubstNonTypeTemplateParmExpr(SubstNonTypeTemplateParmExpr *E) {
103    return Visit(E->getReplacement());
104  }
105
106  // l-values.
107  void VisitDeclRefExpr(DeclRefExpr *DRE) { EmitAggLoadOfLValue(DRE); }
108  void VisitMemberExpr(MemberExpr *ME) { EmitAggLoadOfLValue(ME); }
109  void VisitUnaryDeref(UnaryOperator *E) { EmitAggLoadOfLValue(E); }
110  void VisitStringLiteral(StringLiteral *E) { EmitAggLoadOfLValue(E); }
111  void VisitCompoundLiteralExpr(CompoundLiteralExpr *E);
112  void VisitArraySubscriptExpr(ArraySubscriptExpr *E) {
113    EmitAggLoadOfLValue(E);
114  }
115  void VisitBlockDeclRefExpr(const BlockDeclRefExpr *E) {
116    EmitAggLoadOfLValue(E);
117  }
118  void VisitPredefinedExpr(const PredefinedExpr *E) {
119    EmitAggLoadOfLValue(E);
120  }
121
122  // Operators.
123  void VisitCastExpr(CastExpr *E);
124  void VisitCallExpr(const CallExpr *E);
125  void VisitStmtExpr(const StmtExpr *E);
126  void VisitBinaryOperator(const BinaryOperator *BO);
127  void VisitPointerToDataMemberBinaryOperator(const BinaryOperator *BO);
128  void VisitBinAssign(const BinaryOperator *E);
129  void VisitBinComma(const BinaryOperator *E);
130
131  void VisitObjCMessageExpr(ObjCMessageExpr *E);
132  void VisitObjCIvarRefExpr(ObjCIvarRefExpr *E) {
133    EmitAggLoadOfLValue(E);
134  }
135
136  void VisitAbstractConditionalOperator(const AbstractConditionalOperator *CO);
137  void VisitChooseExpr(const ChooseExpr *CE);
138  void VisitInitListExpr(InitListExpr *E);
139  void VisitImplicitValueInitExpr(ImplicitValueInitExpr *E);
140  void VisitCXXDefaultArgExpr(CXXDefaultArgExpr *DAE) {
141    Visit(DAE->getExpr());
142  }
143  void VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E);
144  void VisitCXXConstructExpr(const CXXConstructExpr *E);
145  void VisitExprWithCleanups(ExprWithCleanups *E);
146  void VisitCXXScalarValueInitExpr(CXXScalarValueInitExpr *E);
147  void VisitCXXTypeidExpr(CXXTypeidExpr *E) { EmitAggLoadOfLValue(E); }
148  void VisitMaterializeTemporaryExpr(MaterializeTemporaryExpr *E);
149  void VisitOpaqueValueExpr(OpaqueValueExpr *E);
150
151  void VisitPseudoObjectExpr(PseudoObjectExpr *E) {
152    if (E->isGLValue()) {
153      LValue LV = CGF.EmitPseudoObjectLValue(E);
154      return EmitFinalDestCopy(E, LV);
155    }
156
157    CGF.EmitPseudoObjectRValue(E, EnsureSlot(E->getType()));
158  }
159
160  void VisitVAArgExpr(VAArgExpr *E);
161
162  void EmitInitializationToLValue(Expr *E, LValue Address);
163  void EmitNullInitializationToLValue(LValue Address);
164  //  case Expr::ChooseExprClass:
165  void VisitCXXThrowExpr(const CXXThrowExpr *E) { CGF.EmitCXXThrowExpr(E); }
166  void VisitAtomicExpr(AtomicExpr *E) {
167    CGF.EmitAtomicExpr(E, EnsureSlot(E->getType()).getAddr());
168  }
169};
170}  // end anonymous namespace.
171
172//===----------------------------------------------------------------------===//
173//                                Utilities
174//===----------------------------------------------------------------------===//
175
176/// EmitAggLoadOfLValue - Given an expression with aggregate type that
177/// represents a value lvalue, this method emits the address of the lvalue,
178/// then loads the result into DestPtr.
179void AggExprEmitter::EmitAggLoadOfLValue(const Expr *E) {
180  LValue LV = CGF.EmitLValue(E);
181  EmitFinalDestCopy(E, LV);
182}
183
184/// \brief True if the given aggregate type requires special GC API calls.
185bool AggExprEmitter::TypeRequiresGCollection(QualType T) {
186  // Only record types have members that might require garbage collection.
187  const RecordType *RecordTy = T->getAs<RecordType>();
188  if (!RecordTy) return false;
189
190  // Don't mess with non-trivial C++ types.
191  RecordDecl *Record = RecordTy->getDecl();
192  if (isa<CXXRecordDecl>(Record) &&
193      (!cast<CXXRecordDecl>(Record)->hasTrivialCopyConstructor() ||
194       !cast<CXXRecordDecl>(Record)->hasTrivialDestructor()))
195    return false;
196
197  // Check whether the type has an object member.
198  return Record->hasObjectMember();
199}
200
201/// \brief Perform the final move to DestPtr if for some reason
202/// getReturnValueSlot() didn't use it directly.
203///
204/// The idea is that you do something like this:
205///   RValue Result = EmitSomething(..., getReturnValueSlot());
206///   EmitMoveFromReturnSlot(E, Result);
207///
208/// If nothing interferes, this will cause the result to be emitted
209/// directly into the return value slot.  Otherwise, a final move
210/// will be performed.
211void AggExprEmitter::EmitMoveFromReturnSlot(const Expr *E, RValue Src) {
212  if (shouldUseDestForReturnSlot()) {
213    // Logically, Dest.getAddr() should equal Src.getAggregateAddr().
214    // The possibility of undef rvalues complicates that a lot,
215    // though, so we can't really assert.
216    return;
217  }
218
219  // Otherwise, do a final copy,
220  assert(Dest.getAddr() != Src.getAggregateAddr());
221  EmitFinalDestCopy(E, Src, /*Ignore*/ true);
222}
223
224/// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired.
225void AggExprEmitter::EmitFinalDestCopy(const Expr *E, RValue Src, bool Ignore,
226                                       unsigned Alignment) {
227  assert(Src.isAggregate() && "value must be aggregate value!");
228
229  // If Dest is ignored, then we're evaluating an aggregate expression
230  // in a context (like an expression statement) that doesn't care
231  // about the result.  C says that an lvalue-to-rvalue conversion is
232  // performed in these cases; C++ says that it is not.  In either
233  // case, we don't actually need to do anything unless the value is
234  // volatile.
235  if (Dest.isIgnored()) {
236    if (!Src.isVolatileQualified() ||
237        CGF.CGM.getLangOptions().CPlusPlus ||
238        (IgnoreResult && Ignore))
239      return;
240
241    // If the source is volatile, we must read from it; to do that, we need
242    // some place to put it.
243    Dest = CGF.CreateAggTemp(E->getType(), "agg.tmp");
244  }
245
246  if (Dest.requiresGCollection()) {
247    CharUnits size = CGF.getContext().getTypeSizeInChars(E->getType());
248    llvm::Type *SizeTy = CGF.ConvertType(CGF.getContext().getSizeType());
249    llvm::Value *SizeVal = llvm::ConstantInt::get(SizeTy, size.getQuantity());
250    CGF.CGM.getObjCRuntime().EmitGCMemmoveCollectable(CGF,
251                                                      Dest.getAddr(),
252                                                      Src.getAggregateAddr(),
253                                                      SizeVal);
254    return;
255  }
256  // If the result of the assignment is used, copy the LHS there also.
257  // FIXME: Pass VolatileDest as well.  I think we also need to merge volatile
258  // from the source as well, as we can't eliminate it if either operand
259  // is volatile, unless copy has volatile for both source and destination..
260  CGF.EmitAggregateCopy(Dest.getAddr(), Src.getAggregateAddr(), E->getType(),
261                        Dest.isVolatile()|Src.isVolatileQualified(),
262                        Alignment);
263}
264
265/// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired.
266void AggExprEmitter::EmitFinalDestCopy(const Expr *E, LValue Src, bool Ignore) {
267  assert(Src.isSimple() && "Can't have aggregate bitfield, vector, etc");
268
269  CharUnits Alignment = std::min(Src.getAlignment(), Dest.getAlignment());
270  EmitFinalDestCopy(E, Src.asAggregateRValue(), Ignore, Alignment.getQuantity());
271}
272
273//===----------------------------------------------------------------------===//
274//                            Visitor Methods
275//===----------------------------------------------------------------------===//
276
277void AggExprEmitter::VisitMaterializeTemporaryExpr(MaterializeTemporaryExpr *E){
278  Visit(E->GetTemporaryExpr());
279}
280
281void AggExprEmitter::VisitOpaqueValueExpr(OpaqueValueExpr *e) {
282  EmitFinalDestCopy(e, CGF.getOpaqueLValueMapping(e));
283}
284
285void
286AggExprEmitter::VisitCompoundLiteralExpr(CompoundLiteralExpr *E) {
287  if (E->getType().isPODType(CGF.getContext())) {
288    // For a POD type, just emit a load of the lvalue + a copy, because our
289    // compound literal might alias the destination.
290    // FIXME: This is a band-aid; the real problem appears to be in our handling
291    // of assignments, where we store directly into the LHS without checking
292    // whether anything in the RHS aliases.
293    EmitAggLoadOfLValue(E);
294    return;
295  }
296
297  AggValueSlot Slot = EnsureSlot(E->getType());
298  CGF.EmitAggExpr(E->getInitializer(), Slot);
299}
300
301
302void AggExprEmitter::VisitCastExpr(CastExpr *E) {
303  switch (E->getCastKind()) {
304  case CK_Dynamic: {
305    assert(isa<CXXDynamicCastExpr>(E) && "CK_Dynamic without a dynamic_cast?");
306    LValue LV = CGF.EmitCheckedLValue(E->getSubExpr());
307    // FIXME: Do we also need to handle property references here?
308    if (LV.isSimple())
309      CGF.EmitDynamicCast(LV.getAddress(), cast<CXXDynamicCastExpr>(E));
310    else
311      CGF.CGM.ErrorUnsupported(E, "non-simple lvalue dynamic_cast");
312
313    if (!Dest.isIgnored())
314      CGF.CGM.ErrorUnsupported(E, "lvalue dynamic_cast with a destination");
315    break;
316  }
317
318  case CK_ToUnion: {
319    if (Dest.isIgnored()) break;
320
321    // GCC union extension
322    QualType Ty = E->getSubExpr()->getType();
323    QualType PtrTy = CGF.getContext().getPointerType(Ty);
324    llvm::Value *CastPtr = Builder.CreateBitCast(Dest.getAddr(),
325                                                 CGF.ConvertType(PtrTy));
326    EmitInitializationToLValue(E->getSubExpr(),
327                               CGF.MakeAddrLValue(CastPtr, Ty));
328    break;
329  }
330
331  case CK_DerivedToBase:
332  case CK_BaseToDerived:
333  case CK_UncheckedDerivedToBase: {
334    llvm_unreachable("cannot perform hierarchy conversion in EmitAggExpr: "
335                "should have been unpacked before we got here");
336  }
337
338  case CK_LValueToRValue: // hope for downstream optimization
339  case CK_NoOp:
340  case CK_UserDefinedConversion:
341  case CK_ConstructorConversion:
342    assert(CGF.getContext().hasSameUnqualifiedType(E->getSubExpr()->getType(),
343                                                   E->getType()) &&
344           "Implicit cast types must be compatible");
345    Visit(E->getSubExpr());
346    break;
347
348  case CK_LValueBitCast:
349    llvm_unreachable("should not be emitting lvalue bitcast as rvalue");
350    break;
351
352  case CK_Dependent:
353  case CK_BitCast:
354  case CK_ArrayToPointerDecay:
355  case CK_FunctionToPointerDecay:
356  case CK_NullToPointer:
357  case CK_NullToMemberPointer:
358  case CK_BaseToDerivedMemberPointer:
359  case CK_DerivedToBaseMemberPointer:
360  case CK_MemberPointerToBoolean:
361  case CK_IntegralToPointer:
362  case CK_PointerToIntegral:
363  case CK_PointerToBoolean:
364  case CK_ToVoid:
365  case CK_VectorSplat:
366  case CK_IntegralCast:
367  case CK_IntegralToBoolean:
368  case CK_IntegralToFloating:
369  case CK_FloatingToIntegral:
370  case CK_FloatingToBoolean:
371  case CK_FloatingCast:
372  case CK_CPointerToObjCPointerCast:
373  case CK_BlockPointerToObjCPointerCast:
374  case CK_AnyPointerToBlockPointerCast:
375  case CK_ObjCObjectLValueCast:
376  case CK_FloatingRealToComplex:
377  case CK_FloatingComplexToReal:
378  case CK_FloatingComplexToBoolean:
379  case CK_FloatingComplexCast:
380  case CK_FloatingComplexToIntegralComplex:
381  case CK_IntegralRealToComplex:
382  case CK_IntegralComplexToReal:
383  case CK_IntegralComplexToBoolean:
384  case CK_IntegralComplexCast:
385  case CK_IntegralComplexToFloatingComplex:
386  case CK_ARCProduceObject:
387  case CK_ARCConsumeObject:
388  case CK_ARCReclaimReturnedObject:
389  case CK_ARCExtendBlockObject:
390    llvm_unreachable("cast kind invalid for aggregate types");
391  }
392}
393
394void AggExprEmitter::VisitCallExpr(const CallExpr *E) {
395  if (E->getCallReturnType()->isReferenceType()) {
396    EmitAggLoadOfLValue(E);
397    return;
398  }
399
400  RValue RV = CGF.EmitCallExpr(E, getReturnValueSlot());
401  EmitMoveFromReturnSlot(E, RV);
402}
403
404void AggExprEmitter::VisitObjCMessageExpr(ObjCMessageExpr *E) {
405  RValue RV = CGF.EmitObjCMessageExpr(E, getReturnValueSlot());
406  EmitMoveFromReturnSlot(E, RV);
407}
408
409void AggExprEmitter::VisitBinComma(const BinaryOperator *E) {
410  CGF.EmitIgnoredExpr(E->getLHS());
411  Visit(E->getRHS());
412}
413
414void AggExprEmitter::VisitStmtExpr(const StmtExpr *E) {
415  CodeGenFunction::StmtExprEvaluation eval(CGF);
416  CGF.EmitCompoundStmt(*E->getSubStmt(), true, Dest);
417}
418
419void AggExprEmitter::VisitBinaryOperator(const BinaryOperator *E) {
420  if (E->getOpcode() == BO_PtrMemD || E->getOpcode() == BO_PtrMemI)
421    VisitPointerToDataMemberBinaryOperator(E);
422  else
423    CGF.ErrorUnsupported(E, "aggregate binary expression");
424}
425
426void AggExprEmitter::VisitPointerToDataMemberBinaryOperator(
427                                                    const BinaryOperator *E) {
428  LValue LV = CGF.EmitPointerToDataMemberBinaryExpr(E);
429  EmitFinalDestCopy(E, LV);
430}
431
432void AggExprEmitter::VisitBinAssign(const BinaryOperator *E) {
433  // For an assignment to work, the value on the right has
434  // to be compatible with the value on the left.
435  assert(CGF.getContext().hasSameUnqualifiedType(E->getLHS()->getType(),
436                                                 E->getRHS()->getType())
437         && "Invalid assignment");
438
439  if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E->getLHS()))
440    if (const VarDecl *VD = dyn_cast<VarDecl>(DRE->getDecl()))
441      if (VD->hasAttr<BlocksAttr>() &&
442          E->getRHS()->HasSideEffects(CGF.getContext())) {
443        // When __block variable on LHS, the RHS must be evaluated first
444        // as it may change the 'forwarding' field via call to Block_copy.
445        LValue RHS = CGF.EmitLValue(E->getRHS());
446        LValue LHS = CGF.EmitLValue(E->getLHS());
447        Dest = AggValueSlot::forLValue(LHS, AggValueSlot::IsDestructed,
448                                       needsGC(E->getLHS()->getType()),
449                                       AggValueSlot::IsAliased);
450        EmitFinalDestCopy(E, RHS, true);
451        return;
452      }
453
454  LValue LHS = CGF.EmitLValue(E->getLHS());
455
456  // Codegen the RHS so that it stores directly into the LHS.
457  AggValueSlot LHSSlot =
458    AggValueSlot::forLValue(LHS, AggValueSlot::IsDestructed,
459                            needsGC(E->getLHS()->getType()),
460                            AggValueSlot::IsAliased);
461  CGF.EmitAggExpr(E->getRHS(), LHSSlot, false);
462  EmitFinalDestCopy(E, LHS, true);
463}
464
465void AggExprEmitter::
466VisitAbstractConditionalOperator(const AbstractConditionalOperator *E) {
467  llvm::BasicBlock *LHSBlock = CGF.createBasicBlock("cond.true");
468  llvm::BasicBlock *RHSBlock = CGF.createBasicBlock("cond.false");
469  llvm::BasicBlock *ContBlock = CGF.createBasicBlock("cond.end");
470
471  // Bind the common expression if necessary.
472  CodeGenFunction::OpaqueValueMapping binding(CGF, E);
473
474  CodeGenFunction::ConditionalEvaluation eval(CGF);
475  CGF.EmitBranchOnBoolExpr(E->getCond(), LHSBlock, RHSBlock);
476
477  // Save whether the destination's lifetime is externally managed.
478  bool isExternallyDestructed = Dest.isExternallyDestructed();
479
480  eval.begin(CGF);
481  CGF.EmitBlock(LHSBlock);
482  Visit(E->getTrueExpr());
483  eval.end(CGF);
484
485  assert(CGF.HaveInsertPoint() && "expression evaluation ended with no IP!");
486  CGF.Builder.CreateBr(ContBlock);
487
488  // If the result of an agg expression is unused, then the emission
489  // of the LHS might need to create a destination slot.  That's fine
490  // with us, and we can safely emit the RHS into the same slot, but
491  // we shouldn't claim that it's already being destructed.
492  Dest.setExternallyDestructed(isExternallyDestructed);
493
494  eval.begin(CGF);
495  CGF.EmitBlock(RHSBlock);
496  Visit(E->getFalseExpr());
497  eval.end(CGF);
498
499  CGF.EmitBlock(ContBlock);
500}
501
502void AggExprEmitter::VisitChooseExpr(const ChooseExpr *CE) {
503  Visit(CE->getChosenSubExpr(CGF.getContext()));
504}
505
506void AggExprEmitter::VisitVAArgExpr(VAArgExpr *VE) {
507  llvm::Value *ArgValue = CGF.EmitVAListRef(VE->getSubExpr());
508  llvm::Value *ArgPtr = CGF.EmitVAArg(ArgValue, VE->getType());
509
510  if (!ArgPtr) {
511    CGF.ErrorUnsupported(VE, "aggregate va_arg expression");
512    return;
513  }
514
515  EmitFinalDestCopy(VE, CGF.MakeAddrLValue(ArgPtr, VE->getType()));
516}
517
518void AggExprEmitter::VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E) {
519  // Ensure that we have a slot, but if we already do, remember
520  // whether it was externally destructed.
521  bool wasExternallyDestructed = Dest.isExternallyDestructed();
522  Dest = EnsureSlot(E->getType());
523
524  // We're going to push a destructor if there isn't already one.
525  Dest.setExternallyDestructed();
526
527  Visit(E->getSubExpr());
528
529  // Push that destructor we promised.
530  if (!wasExternallyDestructed)
531    CGF.EmitCXXTemporary(E->getTemporary(), E->getType(), Dest.getAddr());
532}
533
534void
535AggExprEmitter::VisitCXXConstructExpr(const CXXConstructExpr *E) {
536  AggValueSlot Slot = EnsureSlot(E->getType());
537  CGF.EmitCXXConstructExpr(E, Slot);
538}
539
540void AggExprEmitter::VisitExprWithCleanups(ExprWithCleanups *E) {
541  CGF.enterFullExpression(E);
542  CodeGenFunction::RunCleanupsScope cleanups(CGF);
543  Visit(E->getSubExpr());
544}
545
546void AggExprEmitter::VisitCXXScalarValueInitExpr(CXXScalarValueInitExpr *E) {
547  QualType T = E->getType();
548  AggValueSlot Slot = EnsureSlot(T);
549  EmitNullInitializationToLValue(CGF.MakeAddrLValue(Slot.getAddr(), T));
550}
551
552void AggExprEmitter::VisitImplicitValueInitExpr(ImplicitValueInitExpr *E) {
553  QualType T = E->getType();
554  AggValueSlot Slot = EnsureSlot(T);
555  EmitNullInitializationToLValue(CGF.MakeAddrLValue(Slot.getAddr(), T));
556}
557
558/// isSimpleZero - If emitting this value will obviously just cause a store of
559/// zero to memory, return true.  This can return false if uncertain, so it just
560/// handles simple cases.
561static bool isSimpleZero(const Expr *E, CodeGenFunction &CGF) {
562  E = E->IgnoreParens();
563
564  // 0
565  if (const IntegerLiteral *IL = dyn_cast<IntegerLiteral>(E))
566    return IL->getValue() == 0;
567  // +0.0
568  if (const FloatingLiteral *FL = dyn_cast<FloatingLiteral>(E))
569    return FL->getValue().isPosZero();
570  // int()
571  if ((isa<ImplicitValueInitExpr>(E) || isa<CXXScalarValueInitExpr>(E)) &&
572      CGF.getTypes().isZeroInitializable(E->getType()))
573    return true;
574  // (int*)0 - Null pointer expressions.
575  if (const CastExpr *ICE = dyn_cast<CastExpr>(E))
576    return ICE->getCastKind() == CK_NullToPointer;
577  // '\0'
578  if (const CharacterLiteral *CL = dyn_cast<CharacterLiteral>(E))
579    return CL->getValue() == 0;
580
581  // Otherwise, hard case: conservatively return false.
582  return false;
583}
584
585
586void
587AggExprEmitter::EmitInitializationToLValue(Expr* E, LValue LV) {
588  QualType type = LV.getType();
589  // FIXME: Ignore result?
590  // FIXME: Are initializers affected by volatile?
591  if (Dest.isZeroed() && isSimpleZero(E, CGF)) {
592    // Storing "i32 0" to a zero'd memory location is a noop.
593  } else if (isa<ImplicitValueInitExpr>(E)) {
594    EmitNullInitializationToLValue(LV);
595  } else if (type->isReferenceType()) {
596    RValue RV = CGF.EmitReferenceBindingToExpr(E, /*InitializedDecl=*/0);
597    CGF.EmitStoreThroughLValue(RV, LV);
598  } else if (type->isAnyComplexType()) {
599    CGF.EmitComplexExprIntoAddr(E, LV.getAddress(), false);
600  } else if (CGF.hasAggregateLLVMType(type)) {
601    CGF.EmitAggExpr(E, AggValueSlot::forLValue(LV,
602                                               AggValueSlot::IsDestructed,
603                                      AggValueSlot::DoesNotNeedGCBarriers,
604                                               AggValueSlot::IsNotAliased,
605                                               Dest.isZeroed()));
606  } else if (LV.isSimple()) {
607    CGF.EmitScalarInit(E, /*D=*/0, LV, /*Captured=*/false);
608  } else {
609    CGF.EmitStoreThroughLValue(RValue::get(CGF.EmitScalarExpr(E)), LV);
610  }
611}
612
613void AggExprEmitter::EmitNullInitializationToLValue(LValue lv) {
614  QualType type = lv.getType();
615
616  // If the destination slot is already zeroed out before the aggregate is
617  // copied into it, we don't have to emit any zeros here.
618  if (Dest.isZeroed() && CGF.getTypes().isZeroInitializable(type))
619    return;
620
621  if (!CGF.hasAggregateLLVMType(type)) {
622    // For non-aggregates, we can store zero
623    llvm::Value *null = llvm::Constant::getNullValue(CGF.ConvertType(type));
624    CGF.EmitStoreThroughLValue(RValue::get(null), lv);
625  } else {
626    // There's a potential optimization opportunity in combining
627    // memsets; that would be easy for arrays, but relatively
628    // difficult for structures with the current code.
629    CGF.EmitNullInitialization(lv.getAddress(), lv.getType());
630  }
631}
632
633void AggExprEmitter::VisitInitListExpr(InitListExpr *E) {
634#if 0
635  // FIXME: Assess perf here?  Figure out what cases are worth optimizing here
636  // (Length of globals? Chunks of zeroed-out space?).
637  //
638  // If we can, prefer a copy from a global; this is a lot less code for long
639  // globals, and it's easier for the current optimizers to analyze.
640  if (llvm::Constant* C = CGF.CGM.EmitConstantExpr(E, E->getType(), &CGF)) {
641    llvm::GlobalVariable* GV =
642    new llvm::GlobalVariable(CGF.CGM.getModule(), C->getType(), true,
643                             llvm::GlobalValue::InternalLinkage, C, "");
644    EmitFinalDestCopy(E, CGF.MakeAddrLValue(GV, E->getType()));
645    return;
646  }
647#endif
648  if (E->hadArrayRangeDesignator())
649    CGF.ErrorUnsupported(E, "GNU array range designator extension");
650
651  llvm::Value *DestPtr = Dest.getAddr();
652
653  // Handle initialization of an array.
654  if (E->getType()->isArrayType()) {
655    llvm::PointerType *APType =
656      cast<llvm::PointerType>(DestPtr->getType());
657    llvm::ArrayType *AType =
658      cast<llvm::ArrayType>(APType->getElementType());
659
660    uint64_t NumInitElements = E->getNumInits();
661
662    if (E->getNumInits() > 0) {
663      QualType T1 = E->getType();
664      QualType T2 = E->getInit(0)->getType();
665      if (CGF.getContext().hasSameUnqualifiedType(T1, T2)) {
666        EmitAggLoadOfLValue(E->getInit(0));
667        return;
668      }
669    }
670
671    uint64_t NumArrayElements = AType->getNumElements();
672    assert(NumInitElements <= NumArrayElements);
673
674    QualType elementType = E->getType().getCanonicalType();
675    elementType = CGF.getContext().getQualifiedType(
676                    cast<ArrayType>(elementType)->getElementType(),
677                    elementType.getQualifiers() + Dest.getQualifiers());
678
679    // DestPtr is an array*.  Construct an elementType* by drilling
680    // down a level.
681    llvm::Value *zero = llvm::ConstantInt::get(CGF.SizeTy, 0);
682    llvm::Value *indices[] = { zero, zero };
683    llvm::Value *begin =
684      Builder.CreateInBoundsGEP(DestPtr, indices, "arrayinit.begin");
685
686    // Exception safety requires us to destroy all the
687    // already-constructed members if an initializer throws.
688    // For that, we'll need an EH cleanup.
689    QualType::DestructionKind dtorKind = elementType.isDestructedType();
690    llvm::AllocaInst *endOfInit = 0;
691    EHScopeStack::stable_iterator cleanup;
692    llvm::Instruction *cleanupDominator = 0;
693    if (CGF.needsEHCleanup(dtorKind)) {
694      // In principle we could tell the cleanup where we are more
695      // directly, but the control flow can get so varied here that it
696      // would actually be quite complex.  Therefore we go through an
697      // alloca.
698      endOfInit = CGF.CreateTempAlloca(begin->getType(),
699                                       "arrayinit.endOfInit");
700      cleanupDominator = Builder.CreateStore(begin, endOfInit);
701      CGF.pushIrregularPartialArrayCleanup(begin, endOfInit, elementType,
702                                           CGF.getDestroyer(dtorKind));
703      cleanup = CGF.EHStack.stable_begin();
704
705    // Otherwise, remember that we didn't need a cleanup.
706    } else {
707      dtorKind = QualType::DK_none;
708    }
709
710    llvm::Value *one = llvm::ConstantInt::get(CGF.SizeTy, 1);
711
712    // The 'current element to initialize'.  The invariants on this
713    // variable are complicated.  Essentially, after each iteration of
714    // the loop, it points to the last initialized element, except
715    // that it points to the beginning of the array before any
716    // elements have been initialized.
717    llvm::Value *element = begin;
718
719    // Emit the explicit initializers.
720    for (uint64_t i = 0; i != NumInitElements; ++i) {
721      // Advance to the next element.
722      if (i > 0) {
723        element = Builder.CreateInBoundsGEP(element, one, "arrayinit.element");
724
725        // Tell the cleanup that it needs to destroy up to this
726        // element.  TODO: some of these stores can be trivially
727        // observed to be unnecessary.
728        if (endOfInit) Builder.CreateStore(element, endOfInit);
729      }
730
731      LValue elementLV = CGF.MakeAddrLValue(element, elementType);
732      EmitInitializationToLValue(E->getInit(i), elementLV);
733    }
734
735    // Check whether there's a non-trivial array-fill expression.
736    // Note that this will be a CXXConstructExpr even if the element
737    // type is an array (or array of array, etc.) of class type.
738    Expr *filler = E->getArrayFiller();
739    bool hasTrivialFiller = true;
740    if (CXXConstructExpr *cons = dyn_cast_or_null<CXXConstructExpr>(filler)) {
741      assert(cons->getConstructor()->isDefaultConstructor());
742      hasTrivialFiller = cons->getConstructor()->isTrivial();
743    }
744
745    // Any remaining elements need to be zero-initialized, possibly
746    // using the filler expression.  We can skip this if the we're
747    // emitting to zeroed memory.
748    if (NumInitElements != NumArrayElements &&
749        !(Dest.isZeroed() && hasTrivialFiller &&
750          CGF.getTypes().isZeroInitializable(elementType))) {
751
752      // Use an actual loop.  This is basically
753      //   do { *array++ = filler; } while (array != end);
754
755      // Advance to the start of the rest of the array.
756      if (NumInitElements) {
757        element = Builder.CreateInBoundsGEP(element, one, "arrayinit.start");
758        if (endOfInit) Builder.CreateStore(element, endOfInit);
759      }
760
761      // Compute the end of the array.
762      llvm::Value *end = Builder.CreateInBoundsGEP(begin,
763                        llvm::ConstantInt::get(CGF.SizeTy, NumArrayElements),
764                                                   "arrayinit.end");
765
766      llvm::BasicBlock *entryBB = Builder.GetInsertBlock();
767      llvm::BasicBlock *bodyBB = CGF.createBasicBlock("arrayinit.body");
768
769      // Jump into the body.
770      CGF.EmitBlock(bodyBB);
771      llvm::PHINode *currentElement =
772        Builder.CreatePHI(element->getType(), 2, "arrayinit.cur");
773      currentElement->addIncoming(element, entryBB);
774
775      // Emit the actual filler expression.
776      LValue elementLV = CGF.MakeAddrLValue(currentElement, elementType);
777      if (filler)
778        EmitInitializationToLValue(filler, elementLV);
779      else
780        EmitNullInitializationToLValue(elementLV);
781
782      // Move on to the next element.
783      llvm::Value *nextElement =
784        Builder.CreateInBoundsGEP(currentElement, one, "arrayinit.next");
785
786      // Tell the EH cleanup that we finished with the last element.
787      if (endOfInit) Builder.CreateStore(nextElement, endOfInit);
788
789      // Leave the loop if we're done.
790      llvm::Value *done = Builder.CreateICmpEQ(nextElement, end,
791                                               "arrayinit.done");
792      llvm::BasicBlock *endBB = CGF.createBasicBlock("arrayinit.end");
793      Builder.CreateCondBr(done, endBB, bodyBB);
794      currentElement->addIncoming(nextElement, Builder.GetInsertBlock());
795
796      CGF.EmitBlock(endBB);
797    }
798
799    // Leave the partial-array cleanup if we entered one.
800    if (dtorKind) CGF.DeactivateCleanupBlock(cleanup, cleanupDominator);
801
802    return;
803  }
804
805  assert(E->getType()->isRecordType() && "Only support structs/unions here!");
806
807  // Do struct initialization; this code just sets each individual member
808  // to the approprate value.  This makes bitfield support automatic;
809  // the disadvantage is that the generated code is more difficult for
810  // the optimizer, especially with bitfields.
811  unsigned NumInitElements = E->getNumInits();
812  RecordDecl *record = E->getType()->castAs<RecordType>()->getDecl();
813
814  if (record->isUnion()) {
815    // Only initialize one field of a union. The field itself is
816    // specified by the initializer list.
817    if (!E->getInitializedFieldInUnion()) {
818      // Empty union; we have nothing to do.
819
820#ifndef NDEBUG
821      // Make sure that it's really an empty and not a failure of
822      // semantic analysis.
823      for (RecordDecl::field_iterator Field = record->field_begin(),
824                                   FieldEnd = record->field_end();
825           Field != FieldEnd; ++Field)
826        assert(Field->isUnnamedBitfield() && "Only unnamed bitfields allowed");
827#endif
828      return;
829    }
830
831    // FIXME: volatility
832    FieldDecl *Field = E->getInitializedFieldInUnion();
833
834    LValue FieldLoc = CGF.EmitLValueForFieldInitialization(DestPtr, Field, 0);
835    if (NumInitElements) {
836      // Store the initializer into the field
837      EmitInitializationToLValue(E->getInit(0), FieldLoc);
838    } else {
839      // Default-initialize to null.
840      EmitNullInitializationToLValue(FieldLoc);
841    }
842
843    return;
844  }
845
846  // We'll need to enter cleanup scopes in case any of the member
847  // initializers throw an exception.
848  SmallVector<EHScopeStack::stable_iterator, 16> cleanups;
849  llvm::Instruction *cleanupDominator = 0;
850
851  // Here we iterate over the fields; this makes it simpler to both
852  // default-initialize fields and skip over unnamed fields.
853  unsigned curInitIndex = 0;
854  for (RecordDecl::field_iterator field = record->field_begin(),
855                               fieldEnd = record->field_end();
856       field != fieldEnd; ++field) {
857    // We're done once we hit the flexible array member.
858    if (field->getType()->isIncompleteArrayType())
859      break;
860
861    // Always skip anonymous bitfields.
862    if (field->isUnnamedBitfield())
863      continue;
864
865    // We're done if we reach the end of the explicit initializers, we
866    // have a zeroed object, and the rest of the fields are
867    // zero-initializable.
868    if (curInitIndex == NumInitElements && Dest.isZeroed() &&
869        CGF.getTypes().isZeroInitializable(E->getType()))
870      break;
871
872    // FIXME: volatility
873    LValue LV = CGF.EmitLValueForFieldInitialization(DestPtr, *field, 0);
874    // We never generate write-barries for initialized fields.
875    LV.setNonGC(true);
876
877    if (curInitIndex < NumInitElements) {
878      // Store the initializer into the field.
879      EmitInitializationToLValue(E->getInit(curInitIndex++), LV);
880    } else {
881      // We're out of initalizers; default-initialize to null
882      EmitNullInitializationToLValue(LV);
883    }
884
885    // Push a destructor if necessary.
886    // FIXME: if we have an array of structures, all explicitly
887    // initialized, we can end up pushing a linear number of cleanups.
888    bool pushedCleanup = false;
889    if (QualType::DestructionKind dtorKind
890          = field->getType().isDestructedType()) {
891      assert(LV.isSimple());
892      if (CGF.needsEHCleanup(dtorKind)) {
893        if (!cleanupDominator)
894          cleanupDominator = CGF.Builder.CreateUnreachable(); // placeholder
895
896        CGF.pushDestroy(EHCleanup, LV.getAddress(), field->getType(),
897                        CGF.getDestroyer(dtorKind), false);
898        cleanups.push_back(CGF.EHStack.stable_begin());
899        pushedCleanup = true;
900      }
901    }
902
903    // If the GEP didn't get used because of a dead zero init or something
904    // else, clean it up for -O0 builds and general tidiness.
905    if (!pushedCleanup && LV.isSimple())
906      if (llvm::GetElementPtrInst *GEP =
907            dyn_cast<llvm::GetElementPtrInst>(LV.getAddress()))
908        if (GEP->use_empty())
909          GEP->eraseFromParent();
910  }
911
912  // Deactivate all the partial cleanups in reverse order, which
913  // generally means popping them.
914  for (unsigned i = cleanups.size(); i != 0; --i)
915    CGF.DeactivateCleanupBlock(cleanups[i-1], cleanupDominator);
916
917  // Destroy the placeholder if we made one.
918  if (cleanupDominator)
919    cleanupDominator->eraseFromParent();
920}
921
922//===----------------------------------------------------------------------===//
923//                        Entry Points into this File
924//===----------------------------------------------------------------------===//
925
926/// GetNumNonZeroBytesInInit - Get an approximate count of the number of
927/// non-zero bytes that will be stored when outputting the initializer for the
928/// specified initializer expression.
929static CharUnits GetNumNonZeroBytesInInit(const Expr *E, CodeGenFunction &CGF) {
930  E = E->IgnoreParens();
931
932  // 0 and 0.0 won't require any non-zero stores!
933  if (isSimpleZero(E, CGF)) return CharUnits::Zero();
934
935  // If this is an initlist expr, sum up the size of sizes of the (present)
936  // elements.  If this is something weird, assume the whole thing is non-zero.
937  const InitListExpr *ILE = dyn_cast<InitListExpr>(E);
938  if (ILE == 0 || !CGF.getTypes().isZeroInitializable(ILE->getType()))
939    return CGF.getContext().getTypeSizeInChars(E->getType());
940
941  // InitListExprs for structs have to be handled carefully.  If there are
942  // reference members, we need to consider the size of the reference, not the
943  // referencee.  InitListExprs for unions and arrays can't have references.
944  if (const RecordType *RT = E->getType()->getAs<RecordType>()) {
945    if (!RT->isUnionType()) {
946      RecordDecl *SD = E->getType()->getAs<RecordType>()->getDecl();
947      CharUnits NumNonZeroBytes = CharUnits::Zero();
948
949      unsigned ILEElement = 0;
950      for (RecordDecl::field_iterator Field = SD->field_begin(),
951           FieldEnd = SD->field_end(); Field != FieldEnd; ++Field) {
952        // We're done once we hit the flexible array member or run out of
953        // InitListExpr elements.
954        if (Field->getType()->isIncompleteArrayType() ||
955            ILEElement == ILE->getNumInits())
956          break;
957        if (Field->isUnnamedBitfield())
958          continue;
959
960        const Expr *E = ILE->getInit(ILEElement++);
961
962        // Reference values are always non-null and have the width of a pointer.
963        if (Field->getType()->isReferenceType())
964          NumNonZeroBytes += CGF.getContext().toCharUnitsFromBits(
965              CGF.getContext().getTargetInfo().getPointerWidth(0));
966        else
967          NumNonZeroBytes += GetNumNonZeroBytesInInit(E, CGF);
968      }
969
970      return NumNonZeroBytes;
971    }
972  }
973
974
975  CharUnits NumNonZeroBytes = CharUnits::Zero();
976  for (unsigned i = 0, e = ILE->getNumInits(); i != e; ++i)
977    NumNonZeroBytes += GetNumNonZeroBytesInInit(ILE->getInit(i), CGF);
978  return NumNonZeroBytes;
979}
980
981/// CheckAggExprForMemSetUse - If the initializer is large and has a lot of
982/// zeros in it, emit a memset and avoid storing the individual zeros.
983///
984static void CheckAggExprForMemSetUse(AggValueSlot &Slot, const Expr *E,
985                                     CodeGenFunction &CGF) {
986  // If the slot is already known to be zeroed, nothing to do.  Don't mess with
987  // volatile stores.
988  if (Slot.isZeroed() || Slot.isVolatile() || Slot.getAddr() == 0) return;
989
990  // C++ objects with a user-declared constructor don't need zero'ing.
991  if (CGF.getContext().getLangOptions().CPlusPlus)
992    if (const RecordType *RT = CGF.getContext()
993                       .getBaseElementType(E->getType())->getAs<RecordType>()) {
994      const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
995      if (RD->hasUserDeclaredConstructor())
996        return;
997    }
998
999  // If the type is 16-bytes or smaller, prefer individual stores over memset.
1000  std::pair<CharUnits, CharUnits> TypeInfo =
1001    CGF.getContext().getTypeInfoInChars(E->getType());
1002  if (TypeInfo.first <= CharUnits::fromQuantity(16))
1003    return;
1004
1005  // Check to see if over 3/4 of the initializer are known to be zero.  If so,
1006  // we prefer to emit memset + individual stores for the rest.
1007  CharUnits NumNonZeroBytes = GetNumNonZeroBytesInInit(E, CGF);
1008  if (NumNonZeroBytes*4 > TypeInfo.first)
1009    return;
1010
1011  // Okay, it seems like a good idea to use an initial memset, emit the call.
1012  llvm::Constant *SizeVal = CGF.Builder.getInt64(TypeInfo.first.getQuantity());
1013  CharUnits Align = TypeInfo.second;
1014
1015  llvm::Value *Loc = Slot.getAddr();
1016  llvm::Type *BP = llvm::Type::getInt8PtrTy(CGF.getLLVMContext());
1017
1018  Loc = CGF.Builder.CreateBitCast(Loc, BP);
1019  CGF.Builder.CreateMemSet(Loc, CGF.Builder.getInt8(0), SizeVal,
1020                           Align.getQuantity(), false);
1021
1022  // Tell the AggExprEmitter that the slot is known zero.
1023  Slot.setZeroed();
1024}
1025
1026
1027
1028
1029/// EmitAggExpr - Emit the computation of the specified expression of aggregate
1030/// type.  The result is computed into DestPtr.  Note that if DestPtr is null,
1031/// the value of the aggregate expression is not needed.  If VolatileDest is
1032/// true, DestPtr cannot be 0.
1033///
1034/// \param IsInitializer - true if this evaluation is initializing an
1035/// object whose lifetime is already being managed.
1036void CodeGenFunction::EmitAggExpr(const Expr *E, AggValueSlot Slot,
1037                                  bool IgnoreResult) {
1038  assert(E && hasAggregateLLVMType(E->getType()) &&
1039         "Invalid aggregate expression to emit");
1040  assert((Slot.getAddr() != 0 || Slot.isIgnored()) &&
1041         "slot has bits but no address");
1042
1043  // Optimize the slot if possible.
1044  CheckAggExprForMemSetUse(Slot, E, *this);
1045
1046  AggExprEmitter(*this, Slot, IgnoreResult).Visit(const_cast<Expr*>(E));
1047}
1048
1049LValue CodeGenFunction::EmitAggExprToLValue(const Expr *E) {
1050  assert(hasAggregateLLVMType(E->getType()) && "Invalid argument!");
1051  llvm::Value *Temp = CreateMemTemp(E->getType());
1052  LValue LV = MakeAddrLValue(Temp, E->getType());
1053  EmitAggExpr(E, AggValueSlot::forLValue(LV, AggValueSlot::IsNotDestructed,
1054                                         AggValueSlot::DoesNotNeedGCBarriers,
1055                                         AggValueSlot::IsNotAliased));
1056  return LV;
1057}
1058
1059void CodeGenFunction::EmitAggregateCopy(llvm::Value *DestPtr,
1060                                        llvm::Value *SrcPtr, QualType Ty,
1061                                        bool isVolatile, unsigned Alignment) {
1062  assert(!Ty->isAnyComplexType() && "Shouldn't happen for complex");
1063
1064  if (getContext().getLangOptions().CPlusPlus) {
1065    if (const RecordType *RT = Ty->getAs<RecordType>()) {
1066      CXXRecordDecl *Record = cast<CXXRecordDecl>(RT->getDecl());
1067      assert((Record->hasTrivialCopyConstructor() ||
1068              Record->hasTrivialCopyAssignment() ||
1069              Record->hasTrivialMoveConstructor() ||
1070              Record->hasTrivialMoveAssignment()) &&
1071             "Trying to aggregate-copy a type without a trivial copy "
1072             "constructor or assignment operator");
1073      // Ignore empty classes in C++.
1074      if (Record->isEmpty())
1075        return;
1076    }
1077  }
1078
1079  // Aggregate assignment turns into llvm.memcpy.  This is almost valid per
1080  // C99 6.5.16.1p3, which states "If the value being stored in an object is
1081  // read from another object that overlaps in anyway the storage of the first
1082  // object, then the overlap shall be exact and the two objects shall have
1083  // qualified or unqualified versions of a compatible type."
1084  //
1085  // memcpy is not defined if the source and destination pointers are exactly
1086  // equal, but other compilers do this optimization, and almost every memcpy
1087  // implementation handles this case safely.  If there is a libc that does not
1088  // safely handle this, we can add a target hook.
1089
1090  // Get size and alignment info for this aggregate.
1091  std::pair<CharUnits, CharUnits> TypeInfo =
1092    getContext().getTypeInfoInChars(Ty);
1093
1094  if (!Alignment)
1095    Alignment = TypeInfo.second.getQuantity();
1096
1097  // FIXME: Handle variable sized types.
1098
1099  // FIXME: If we have a volatile struct, the optimizer can remove what might
1100  // appear to be `extra' memory ops:
1101  //
1102  // volatile struct { int i; } a, b;
1103  //
1104  // int main() {
1105  //   a = b;
1106  //   a = b;
1107  // }
1108  //
1109  // we need to use a different call here.  We use isVolatile to indicate when
1110  // either the source or the destination is volatile.
1111
1112  llvm::PointerType *DPT = cast<llvm::PointerType>(DestPtr->getType());
1113  llvm::Type *DBP =
1114    llvm::Type::getInt8PtrTy(getLLVMContext(), DPT->getAddressSpace());
1115  DestPtr = Builder.CreateBitCast(DestPtr, DBP);
1116
1117  llvm::PointerType *SPT = cast<llvm::PointerType>(SrcPtr->getType());
1118  llvm::Type *SBP =
1119    llvm::Type::getInt8PtrTy(getLLVMContext(), SPT->getAddressSpace());
1120  SrcPtr = Builder.CreateBitCast(SrcPtr, SBP);
1121
1122  // Don't do any of the memmove_collectable tests if GC isn't set.
1123  if (CGM.getLangOptions().getGC() == LangOptions::NonGC) {
1124    // fall through
1125  } else if (const RecordType *RecordTy = Ty->getAs<RecordType>()) {
1126    RecordDecl *Record = RecordTy->getDecl();
1127    if (Record->hasObjectMember()) {
1128      CharUnits size = TypeInfo.first;
1129      llvm::Type *SizeTy = ConvertType(getContext().getSizeType());
1130      llvm::Value *SizeVal = llvm::ConstantInt::get(SizeTy, size.getQuantity());
1131      CGM.getObjCRuntime().EmitGCMemmoveCollectable(*this, DestPtr, SrcPtr,
1132                                                    SizeVal);
1133      return;
1134    }
1135  } else if (Ty->isArrayType()) {
1136    QualType BaseType = getContext().getBaseElementType(Ty);
1137    if (const RecordType *RecordTy = BaseType->getAs<RecordType>()) {
1138      if (RecordTy->getDecl()->hasObjectMember()) {
1139        CharUnits size = TypeInfo.first;
1140        llvm::Type *SizeTy = ConvertType(getContext().getSizeType());
1141        llvm::Value *SizeVal =
1142          llvm::ConstantInt::get(SizeTy, size.getQuantity());
1143        CGM.getObjCRuntime().EmitGCMemmoveCollectable(*this, DestPtr, SrcPtr,
1144                                                      SizeVal);
1145        return;
1146      }
1147    }
1148  }
1149
1150  Builder.CreateMemCpy(DestPtr, SrcPtr,
1151                       llvm::ConstantInt::get(IntPtrTy,
1152                                              TypeInfo.first.getQuantity()),
1153                       Alignment, isVolatile);
1154}
1155