1 //===-- CGValue.h - LLVM CodeGen wrappers for llvm::Value* ------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // These classes implement wrappers around llvm::Value in order to
10 // fully represent the range of values for C L- and R- values.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef LLVM_CLANG_LIB_CODEGEN_CGVALUE_H
15 #define LLVM_CLANG_LIB_CODEGEN_CGVALUE_H
16 
17 #include "clang/AST/ASTContext.h"
18 #include "clang/AST/Type.h"
19 #include "llvm/IR/Value.h"
20 #include "llvm/IR/Type.h"
21 #include "Address.h"
22 #include "CodeGenTBAA.h"
23 
24 namespace llvm {
25   class Constant;
26   class MDNode;
27 }
28 
29 namespace clang {
30 namespace CodeGen {
31   class AggValueSlot;
32   class CodeGenFunction;
33   struct CGBitFieldInfo;
34 
35 /// RValue - This trivial value class is used to represent the result of an
36 /// expression that is evaluated.  It can be one of three things: either a
37 /// simple LLVM SSA value, a pair of SSA values for complex numbers, or the
38 /// address of an aggregate value in memory.
39 class RValue {
40   enum Flavor { Scalar, Complex, Aggregate };
41 
42   // The shift to make to an aggregate's alignment to make it look
43   // like a pointer.
44   enum { AggAlignShift = 4 };
45 
46   // Stores first value and flavor.
47   llvm::PointerIntPair<llvm::Value *, 2, Flavor> V1;
48   // Stores second value and volatility.
49   llvm::PointerIntPair<llvm::Value *, 1, bool> V2;
50   // Stores element type for aggregate values.
51   llvm::Type *ElementType;
52 
53 public:
54   bool isScalar() const { return V1.getInt() == Scalar; }
55   bool isComplex() const { return V1.getInt() == Complex; }
56   bool isAggregate() const { return V1.getInt() == Aggregate; }
57 
58   bool isVolatileQualified() const { return V2.getInt(); }
59 
60   /// getScalarVal() - Return the Value* of this scalar value.
61   llvm::Value *getScalarVal() const {
62     assert(isScalar() && "Not a scalar!");
63     return V1.getPointer();
64   }
65 
66   /// getComplexVal - Return the real/imag components of this complex value.
67   ///
68   std::pair<llvm::Value *, llvm::Value *> getComplexVal() const {
69     return std::make_pair(V1.getPointer(), V2.getPointer());
70   }
71 
72   /// getAggregateAddr() - Return the Value* of the address of the aggregate.
73   Address getAggregateAddress() const {
74     assert(isAggregate() && "Not an aggregate!");
75     auto align = reinterpret_cast<uintptr_t>(V2.getPointer()) >> AggAlignShift;
76     return Address(
77         V1.getPointer(), ElementType, CharUnits::fromQuantity(align));
78   }
79   llvm::Value *getAggregatePointer() const {
80     assert(isAggregate() && "Not an aggregate!");
81     return V1.getPointer();
82   }
83 
84   static RValue getIgnored() {
85     // FIXME: should we make this a more explicit state?
86     return get(nullptr);
87   }
88 
89   static RValue get(llvm::Value *V) {
90     RValue ER;
91     ER.V1.setPointer(V);
92     ER.V1.setInt(Scalar);
93     ER.V2.setInt(false);
94     return ER;
95   }
96   static RValue getComplex(llvm::Value *V1, llvm::Value *V2) {
97     RValue ER;
98     ER.V1.setPointer(V1);
99     ER.V2.setPointer(V2);
100     ER.V1.setInt(Complex);
101     ER.V2.setInt(false);
102     return ER;
103   }
104   static RValue getComplex(const std::pair<llvm::Value *, llvm::Value *> &C) {
105     return getComplex(C.first, C.second);
106   }
107   // FIXME: Aggregate rvalues need to retain information about whether they are
108   // volatile or not.  Remove default to find all places that probably get this
109   // wrong.
110   static RValue getAggregate(Address addr, bool isVolatile = false) {
111     RValue ER;
112     ER.V1.setPointer(addr.getPointer());
113     ER.V1.setInt(Aggregate);
114     ER.ElementType = addr.getElementType();
115 
116     auto align = static_cast<uintptr_t>(addr.getAlignment().getQuantity());
117     ER.V2.setPointer(reinterpret_cast<llvm::Value*>(align << AggAlignShift));
118     ER.V2.setInt(isVolatile);
119     return ER;
120   }
121 };
122 
123 /// Does an ARC strong l-value have precise lifetime?
124 enum ARCPreciseLifetime_t {
125   ARCImpreciseLifetime, ARCPreciseLifetime
126 };
127 
128 /// The source of the alignment of an l-value; an expression of
129 /// confidence in the alignment actually matching the estimate.
130 enum class AlignmentSource {
131   /// The l-value was an access to a declared entity or something
132   /// equivalently strong, like the address of an array allocated by a
133   /// language runtime.
134   Decl,
135 
136   /// The l-value was considered opaque, so the alignment was
137   /// determined from a type, but that type was an explicitly-aligned
138   /// typedef.
139   AttributedType,
140 
141   /// The l-value was considered opaque, so the alignment was
142   /// determined from a type.
143   Type
144 };
145 
146 /// Given that the base address has the given alignment source, what's
147 /// our confidence in the alignment of the field?
148 static inline AlignmentSource getFieldAlignmentSource(AlignmentSource Source) {
149   // For now, we don't distinguish fields of opaque pointers from
150   // top-level declarations, but maybe we should.
151   return AlignmentSource::Decl;
152 }
153 
154 class LValueBaseInfo {
155   AlignmentSource AlignSource;
156 
157 public:
158   explicit LValueBaseInfo(AlignmentSource Source = AlignmentSource::Type)
159     : AlignSource(Source) {}
160   AlignmentSource getAlignmentSource() const { return AlignSource; }
161   void setAlignmentSource(AlignmentSource Source) { AlignSource = Source; }
162 
163   void mergeForCast(const LValueBaseInfo &Info) {
164     setAlignmentSource(Info.getAlignmentSource());
165   }
166 };
167 
168 /// LValue - This represents an lvalue references.  Because C/C++ allow
169 /// bitfields, this is not a simple LLVM pointer, it may be a pointer plus a
170 /// bitrange.
171 class LValue {
172   enum {
173     Simple,       // This is a normal l-value, use getAddress().
174     VectorElt,    // This is a vector element l-value (V[i]), use getVector*
175     BitField,     // This is a bitfield l-value, use getBitfield*.
176     ExtVectorElt, // This is an extended vector subset, use getExtVectorComp
177     GlobalReg,    // This is a register l-value, use getGlobalReg()
178     MatrixElt     // This is a matrix element, use getVector*
179   } LVType;
180 
181   llvm::Value *V;
182   llvm::Type *ElementType;
183 
184   union {
185     // Index into a vector subscript: V[i]
186     llvm::Value *VectorIdx;
187 
188     // ExtVector element subset: V.xyx
189     llvm::Constant *VectorElts;
190 
191     // BitField start bit and size
192     const CGBitFieldInfo *BitFieldInfo;
193   };
194 
195   QualType Type;
196 
197   // 'const' is unused here
198   Qualifiers Quals;
199 
200   // The alignment to use when accessing this lvalue.  (For vector elements,
201   // this is the alignment of the whole vector.)
202   unsigned Alignment;
203 
204   // objective-c's ivar
205   bool Ivar:1;
206 
207   // objective-c's ivar is an array
208   bool ObjIsArray:1;
209 
210   // LValue is non-gc'able for any reason, including being a parameter or local
211   // variable.
212   bool NonGC: 1;
213 
214   // Lvalue is a global reference of an objective-c object
215   bool GlobalObjCRef : 1;
216 
217   // Lvalue is a thread local reference
218   bool ThreadLocalRef : 1;
219 
220   // Lvalue has ARC imprecise lifetime.  We store this inverted to try
221   // to make the default bitfield pattern all-zeroes.
222   bool ImpreciseLifetime : 1;
223 
224   // This flag shows if a nontemporal load/stores should be used when accessing
225   // this lvalue.
226   bool Nontemporal : 1;
227 
228   // The pointer is known not to be null.
229   bool IsKnownNonNull : 1;
230 
231   LValueBaseInfo BaseInfo;
232   TBAAAccessInfo TBAAInfo;
233 
234   Expr *BaseIvarExp;
235 
236 private:
237   void Initialize(QualType Type, Qualifiers Quals, CharUnits Alignment,
238                   LValueBaseInfo BaseInfo, TBAAAccessInfo TBAAInfo) {
239     assert((!Alignment.isZero() || Type->isIncompleteType()) &&
240            "initializing l-value with zero alignment!");
241     if (isGlobalReg())
242       assert(ElementType == nullptr && "Global reg does not store elem type");
243     else
244       assert(ElementType != nullptr && "Must have elem type");
245 
246     this->Type = Type;
247     this->Quals = Quals;
248     const unsigned MaxAlign = 1U << 31;
249     this->Alignment = Alignment.getQuantity() <= MaxAlign
250                           ? Alignment.getQuantity()
251                           : MaxAlign;
252     assert(this->Alignment == Alignment.getQuantity() &&
253            "Alignment exceeds allowed max!");
254     this->BaseInfo = BaseInfo;
255     this->TBAAInfo = TBAAInfo;
256 
257     // Initialize Objective-C flags.
258     this->Ivar = this->ObjIsArray = this->NonGC = this->GlobalObjCRef = false;
259     this->ImpreciseLifetime = false;
260     this->Nontemporal = false;
261     this->ThreadLocalRef = false;
262     this->BaseIvarExp = nullptr;
263   }
264 
265 public:
266   bool isSimple() const { return LVType == Simple; }
267   bool isVectorElt() const { return LVType == VectorElt; }
268   bool isBitField() const { return LVType == BitField; }
269   bool isExtVectorElt() const { return LVType == ExtVectorElt; }
270   bool isGlobalReg() const { return LVType == GlobalReg; }
271   bool isMatrixElt() const { return LVType == MatrixElt; }
272 
273   bool isVolatileQualified() const { return Quals.hasVolatile(); }
274   bool isRestrictQualified() const { return Quals.hasRestrict(); }
275   unsigned getVRQualifiers() const {
276     return Quals.getCVRQualifiers() & ~Qualifiers::Const;
277   }
278 
279   QualType getType() const { return Type; }
280 
281   Qualifiers::ObjCLifetime getObjCLifetime() const {
282     return Quals.getObjCLifetime();
283   }
284 
285   bool isObjCIvar() const { return Ivar; }
286   void setObjCIvar(bool Value) { Ivar = Value; }
287 
288   bool isObjCArray() const { return ObjIsArray; }
289   void setObjCArray(bool Value) { ObjIsArray = Value; }
290 
291   bool isNonGC () const { return NonGC; }
292   void setNonGC(bool Value) { NonGC = Value; }
293 
294   bool isGlobalObjCRef() const { return GlobalObjCRef; }
295   void setGlobalObjCRef(bool Value) { GlobalObjCRef = Value; }
296 
297   bool isThreadLocalRef() const { return ThreadLocalRef; }
298   void setThreadLocalRef(bool Value) { ThreadLocalRef = Value;}
299 
300   ARCPreciseLifetime_t isARCPreciseLifetime() const {
301     return ARCPreciseLifetime_t(!ImpreciseLifetime);
302   }
303   void setARCPreciseLifetime(ARCPreciseLifetime_t value) {
304     ImpreciseLifetime = (value == ARCImpreciseLifetime);
305   }
306   bool isNontemporal() const { return Nontemporal; }
307   void setNontemporal(bool Value) { Nontemporal = Value; }
308 
309   bool isObjCWeak() const {
310     return Quals.getObjCGCAttr() == Qualifiers::Weak;
311   }
312   bool isObjCStrong() const {
313     return Quals.getObjCGCAttr() == Qualifiers::Strong;
314   }
315 
316   bool isVolatile() const {
317     return Quals.hasVolatile();
318   }
319 
320   Expr *getBaseIvarExp() const { return BaseIvarExp; }
321   void setBaseIvarExp(Expr *V) { BaseIvarExp = V; }
322 
323   TBAAAccessInfo getTBAAInfo() const { return TBAAInfo; }
324   void setTBAAInfo(TBAAAccessInfo Info) { TBAAInfo = Info; }
325 
326   const Qualifiers &getQuals() const { return Quals; }
327   Qualifiers &getQuals() { return Quals; }
328 
329   LangAS getAddressSpace() const { return Quals.getAddressSpace(); }
330 
331   CharUnits getAlignment() const { return CharUnits::fromQuantity(Alignment); }
332   void setAlignment(CharUnits A) { Alignment = A.getQuantity(); }
333 
334   LValueBaseInfo getBaseInfo() const { return BaseInfo; }
335   void setBaseInfo(LValueBaseInfo Info) { BaseInfo = Info; }
336 
337   KnownNonNull_t isKnownNonNull() const {
338     return (KnownNonNull_t)IsKnownNonNull;
339   }
340   LValue setKnownNonNull() {
341     IsKnownNonNull = true;
342     return *this;
343   }
344 
345   // simple lvalue
346   llvm::Value *getPointer(CodeGenFunction &CGF) const {
347     assert(isSimple());
348     return V;
349   }
350   Address getAddress(CodeGenFunction &CGF) const {
351     return Address(getPointer(CGF), ElementType, getAlignment(),
352                    isKnownNonNull());
353   }
354   void setAddress(Address address) {
355     assert(isSimple());
356     V = address.getPointer();
357     ElementType = address.getElementType();
358     Alignment = address.getAlignment().getQuantity();
359     IsKnownNonNull = address.isKnownNonNull();
360   }
361 
362   // vector elt lvalue
363   Address getVectorAddress() const {
364     return Address(getVectorPointer(), ElementType, getAlignment(),
365                    (KnownNonNull_t)isKnownNonNull());
366   }
367   llvm::Value *getVectorPointer() const {
368     assert(isVectorElt());
369     return V;
370   }
371   llvm::Value *getVectorIdx() const {
372     assert(isVectorElt());
373     return VectorIdx;
374   }
375 
376   Address getMatrixAddress() const {
377     return Address(getMatrixPointer(), ElementType, getAlignment(),
378                    (KnownNonNull_t)isKnownNonNull());
379   }
380   llvm::Value *getMatrixPointer() const {
381     assert(isMatrixElt());
382     return V;
383   }
384   llvm::Value *getMatrixIdx() const {
385     assert(isMatrixElt());
386     return VectorIdx;
387   }
388 
389   // extended vector elements.
390   Address getExtVectorAddress() const {
391     return Address(getExtVectorPointer(), ElementType, getAlignment(),
392                    (KnownNonNull_t)isKnownNonNull());
393   }
394   llvm::Value *getExtVectorPointer() const {
395     assert(isExtVectorElt());
396     return V;
397   }
398   llvm::Constant *getExtVectorElts() const {
399     assert(isExtVectorElt());
400     return VectorElts;
401   }
402 
403   // bitfield lvalue
404   Address getBitFieldAddress() const {
405     return Address(getBitFieldPointer(), ElementType, getAlignment(),
406                    (KnownNonNull_t)isKnownNonNull());
407   }
408   llvm::Value *getBitFieldPointer() const { assert(isBitField()); return V; }
409   const CGBitFieldInfo &getBitFieldInfo() const {
410     assert(isBitField());
411     return *BitFieldInfo;
412   }
413 
414   // global register lvalue
415   llvm::Value *getGlobalReg() const { assert(isGlobalReg()); return V; }
416 
417   static LValue MakeAddr(Address address, QualType type, ASTContext &Context,
418                          LValueBaseInfo BaseInfo, TBAAAccessInfo TBAAInfo) {
419     Qualifiers qs = type.getQualifiers();
420     qs.setObjCGCAttr(Context.getObjCGCAttrKind(type));
421 
422     LValue R;
423     R.LVType = Simple;
424     assert(address.getPointer()->getType()->isPointerTy());
425     R.V = address.getPointer();
426     R.ElementType = address.getElementType();
427     R.IsKnownNonNull = address.isKnownNonNull();
428     R.Initialize(type, qs, address.getAlignment(), BaseInfo, TBAAInfo);
429     return R;
430   }
431 
432   static LValue MakeVectorElt(Address vecAddress, llvm::Value *Idx,
433                               QualType type, LValueBaseInfo BaseInfo,
434                               TBAAAccessInfo TBAAInfo) {
435     LValue R;
436     R.LVType = VectorElt;
437     R.V = vecAddress.getPointer();
438     R.ElementType = vecAddress.getElementType();
439     R.VectorIdx = Idx;
440     R.IsKnownNonNull = vecAddress.isKnownNonNull();
441     R.Initialize(type, type.getQualifiers(), vecAddress.getAlignment(),
442                  BaseInfo, TBAAInfo);
443     return R;
444   }
445 
446   static LValue MakeExtVectorElt(Address vecAddress, llvm::Constant *Elts,
447                                  QualType type, LValueBaseInfo BaseInfo,
448                                  TBAAAccessInfo TBAAInfo) {
449     LValue R;
450     R.LVType = ExtVectorElt;
451     R.V = vecAddress.getPointer();
452     R.ElementType = vecAddress.getElementType();
453     R.VectorElts = Elts;
454     R.IsKnownNonNull = vecAddress.isKnownNonNull();
455     R.Initialize(type, type.getQualifiers(), vecAddress.getAlignment(),
456                  BaseInfo, TBAAInfo);
457     return R;
458   }
459 
460   /// Create a new object to represent a bit-field access.
461   ///
462   /// \param Addr - The base address of the bit-field sequence this
463   /// bit-field refers to.
464   /// \param Info - The information describing how to perform the bit-field
465   /// access.
466   static LValue MakeBitfield(Address Addr, const CGBitFieldInfo &Info,
467                              QualType type, LValueBaseInfo BaseInfo,
468                              TBAAAccessInfo TBAAInfo) {
469     LValue R;
470     R.LVType = BitField;
471     R.V = Addr.getPointer();
472     R.ElementType = Addr.getElementType();
473     R.BitFieldInfo = &Info;
474     R.IsKnownNonNull = Addr.isKnownNonNull();
475     R.Initialize(type, type.getQualifiers(), Addr.getAlignment(), BaseInfo,
476                  TBAAInfo);
477     return R;
478   }
479 
480   static LValue MakeGlobalReg(llvm::Value *V, CharUnits alignment,
481                               QualType type) {
482     LValue R;
483     R.LVType = GlobalReg;
484     R.V = V;
485     R.ElementType = nullptr;
486     R.IsKnownNonNull = true;
487     R.Initialize(type, type.getQualifiers(), alignment,
488                  LValueBaseInfo(AlignmentSource::Decl), TBAAAccessInfo());
489     return R;
490   }
491 
492   static LValue MakeMatrixElt(Address matAddress, llvm::Value *Idx,
493                               QualType type, LValueBaseInfo BaseInfo,
494                               TBAAAccessInfo TBAAInfo) {
495     LValue R;
496     R.LVType = MatrixElt;
497     R.V = matAddress.getPointer();
498     R.ElementType = matAddress.getElementType();
499     R.VectorIdx = Idx;
500     R.IsKnownNonNull = matAddress.isKnownNonNull();
501     R.Initialize(type, type.getQualifiers(), matAddress.getAlignment(),
502                  BaseInfo, TBAAInfo);
503     return R;
504   }
505 
506   RValue asAggregateRValue(CodeGenFunction &CGF) const {
507     return RValue::getAggregate(getAddress(CGF), isVolatileQualified());
508   }
509 };
510 
511 /// An aggregate value slot.
512 class AggValueSlot {
513   /// The address.
514   Address Addr;
515 
516   // Qualifiers
517   Qualifiers Quals;
518 
519   /// DestructedFlag - This is set to true if some external code is
520   /// responsible for setting up a destructor for the slot.  Otherwise
521   /// the code which constructs it should push the appropriate cleanup.
522   bool DestructedFlag : 1;
523 
524   /// ObjCGCFlag - This is set to true if writing to the memory in the
525   /// slot might require calling an appropriate Objective-C GC
526   /// barrier.  The exact interaction here is unnecessarily mysterious.
527   bool ObjCGCFlag : 1;
528 
529   /// ZeroedFlag - This is set to true if the memory in the slot is
530   /// known to be zero before the assignment into it.  This means that
531   /// zero fields don't need to be set.
532   bool ZeroedFlag : 1;
533 
534   /// AliasedFlag - This is set to true if the slot might be aliased
535   /// and it's not undefined behavior to access it through such an
536   /// alias.  Note that it's always undefined behavior to access a C++
537   /// object that's under construction through an alias derived from
538   /// outside the construction process.
539   ///
540   /// This flag controls whether calls that produce the aggregate
541   /// value may be evaluated directly into the slot, or whether they
542   /// must be evaluated into an unaliased temporary and then memcpy'ed
543   /// over.  Since it's invalid in general to memcpy a non-POD C++
544   /// object, it's important that this flag never be set when
545   /// evaluating an expression which constructs such an object.
546   bool AliasedFlag : 1;
547 
548   /// This is set to true if the tail padding of this slot might overlap
549   /// another object that may have already been initialized (and whose
550   /// value must be preserved by this initialization). If so, we may only
551   /// store up to the dsize of the type. Otherwise we can widen stores to
552   /// the size of the type.
553   bool OverlapFlag : 1;
554 
555   /// If is set to true, sanitizer checks are already generated for this address
556   /// or not required. For instance, if this address represents an object
557   /// created in 'new' expression, sanitizer checks for memory is made as a part
558   /// of 'operator new' emission and object constructor should not generate
559   /// them.
560   bool SanitizerCheckedFlag : 1;
561 
562   AggValueSlot(Address Addr, Qualifiers Quals, bool DestructedFlag,
563                bool ObjCGCFlag, bool ZeroedFlag, bool AliasedFlag,
564                bool OverlapFlag, bool SanitizerCheckedFlag)
565       : Addr(Addr), Quals(Quals), DestructedFlag(DestructedFlag),
566         ObjCGCFlag(ObjCGCFlag), ZeroedFlag(ZeroedFlag),
567         AliasedFlag(AliasedFlag), OverlapFlag(OverlapFlag),
568         SanitizerCheckedFlag(SanitizerCheckedFlag) {}
569 
570 public:
571   enum IsAliased_t { IsNotAliased, IsAliased };
572   enum IsDestructed_t { IsNotDestructed, IsDestructed };
573   enum IsZeroed_t { IsNotZeroed, IsZeroed };
574   enum Overlap_t { DoesNotOverlap, MayOverlap };
575   enum NeedsGCBarriers_t { DoesNotNeedGCBarriers, NeedsGCBarriers };
576   enum IsSanitizerChecked_t { IsNotSanitizerChecked, IsSanitizerChecked };
577 
578   /// ignored - Returns an aggregate value slot indicating that the
579   /// aggregate value is being ignored.
580   static AggValueSlot ignored() {
581     return forAddr(Address::invalid(), Qualifiers(), IsNotDestructed,
582                    DoesNotNeedGCBarriers, IsNotAliased, DoesNotOverlap);
583   }
584 
585   /// forAddr - Make a slot for an aggregate value.
586   ///
587   /// \param quals - The qualifiers that dictate how the slot should
588   /// be initialied. Only 'volatile' and the Objective-C lifetime
589   /// qualifiers matter.
590   ///
591   /// \param isDestructed - true if something else is responsible
592   ///   for calling destructors on this object
593   /// \param needsGC - true if the slot is potentially located
594   ///   somewhere that ObjC GC calls should be emitted for
595   static AggValueSlot forAddr(Address addr,
596                               Qualifiers quals,
597                               IsDestructed_t isDestructed,
598                               NeedsGCBarriers_t needsGC,
599                               IsAliased_t isAliased,
600                               Overlap_t mayOverlap,
601                               IsZeroed_t isZeroed = IsNotZeroed,
602                        IsSanitizerChecked_t isChecked = IsNotSanitizerChecked) {
603     if (addr.isValid())
604       addr.setKnownNonNull();
605     return AggValueSlot(addr, quals, isDestructed, needsGC, isZeroed, isAliased,
606                         mayOverlap, isChecked);
607   }
608 
609   static AggValueSlot
610   forLValue(const LValue &LV, CodeGenFunction &CGF, IsDestructed_t isDestructed,
611             NeedsGCBarriers_t needsGC, IsAliased_t isAliased,
612             Overlap_t mayOverlap, IsZeroed_t isZeroed = IsNotZeroed,
613             IsSanitizerChecked_t isChecked = IsNotSanitizerChecked) {
614     return forAddr(LV.getAddress(CGF), LV.getQuals(), isDestructed, needsGC,
615                    isAliased, mayOverlap, isZeroed, isChecked);
616   }
617 
618   IsDestructed_t isExternallyDestructed() const {
619     return IsDestructed_t(DestructedFlag);
620   }
621   void setExternallyDestructed(bool destructed = true) {
622     DestructedFlag = destructed;
623   }
624 
625   Qualifiers getQualifiers() const { return Quals; }
626 
627   bool isVolatile() const {
628     return Quals.hasVolatile();
629   }
630 
631   void setVolatile(bool flag) {
632     if (flag)
633       Quals.addVolatile();
634     else
635       Quals.removeVolatile();
636   }
637 
638   Qualifiers::ObjCLifetime getObjCLifetime() const {
639     return Quals.getObjCLifetime();
640   }
641 
642   NeedsGCBarriers_t requiresGCollection() const {
643     return NeedsGCBarriers_t(ObjCGCFlag);
644   }
645 
646   llvm::Value *getPointer() const {
647     return Addr.getPointer();
648   }
649 
650   Address getAddress() const {
651     return Addr;
652   }
653 
654   bool isIgnored() const {
655     return !Addr.isValid();
656   }
657 
658   CharUnits getAlignment() const {
659     return Addr.getAlignment();
660   }
661 
662   IsAliased_t isPotentiallyAliased() const {
663     return IsAliased_t(AliasedFlag);
664   }
665 
666   Overlap_t mayOverlap() const {
667     return Overlap_t(OverlapFlag);
668   }
669 
670   bool isSanitizerChecked() const {
671     return SanitizerCheckedFlag;
672   }
673 
674   RValue asRValue() const {
675     if (isIgnored()) {
676       return RValue::getIgnored();
677     } else {
678       return RValue::getAggregate(getAddress(), isVolatile());
679     }
680   }
681 
682   void setZeroed(bool V = true) { ZeroedFlag = V; }
683   IsZeroed_t isZeroed() const {
684     return IsZeroed_t(ZeroedFlag);
685   }
686 
687   /// Get the preferred size to use when storing a value to this slot. This
688   /// is the type size unless that might overlap another object, in which
689   /// case it's the dsize.
690   CharUnits getPreferredSize(ASTContext &Ctx, QualType Type) const {
691     return mayOverlap() ? Ctx.getTypeInfoDataSizeInChars(Type).Width
692                         : Ctx.getTypeSizeInChars(Type);
693   }
694 };
695 
696 }  // end namespace CodeGen
697 }  // end namespace clang
698 
699 #endif
700