1 //===-- CGValue.h - LLVM CodeGen wrappers for llvm::Value* ------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // These classes implement wrappers around llvm::Value in order to
11 // fully represent the range of values for C L- and R- values.
13 //===----------------------------------------------------------------------===//
15 #ifndef LLVM_CLANG_LIB_CODEGEN_CGVALUE_H
16 #define LLVM_CLANG_LIB_CODEGEN_CGVALUE_H
18 #include "clang/AST/ASTContext.h"
19 #include "clang/AST/Type.h"
20 #include "llvm/IR/Value.h"
21 #include "llvm/IR/Type.h"
23 #include "CodeGenTBAA.h"
33 struct CGBitFieldInfo;
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.
40 enum Flavor { Scalar, Complex, Aggregate };
42 // The shift to make to an aggregate's alignment to make it look
44 enum { AggAlignShift = 4 };
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;
52 bool isScalar() const { return V1.getInt() == Scalar; }
53 bool isComplex() const { return V1.getInt() == Complex; }
54 bool isAggregate() const { return V1.getInt() == Aggregate; }
56 bool isVolatileQualified() const { return V2.getInt(); }
58 /// getScalarVal() - Return the Value* of this scalar value.
59 llvm::Value *getScalarVal() const {
60 assert(isScalar() && "Not a scalar!");
61 return V1.getPointer();
64 /// getComplexVal - Return the real/imag components of this complex value.
66 std::pair<llvm::Value *, llvm::Value *> getComplexVal() const {
67 return std::make_pair(V1.getPointer(), V2.getPointer());
70 /// getAggregateAddr() - Return the Value* of the address of the aggregate.
71 Address getAggregateAddress() const {
72 assert(isAggregate() && "Not an aggregate!");
73 auto align = reinterpret_cast<uintptr_t>(V2.getPointer()) >> AggAlignShift;
74 return Address(V1.getPointer(), CharUnits::fromQuantity(align));
76 llvm::Value *getAggregatePointer() const {
77 assert(isAggregate() && "Not an aggregate!");
78 return V1.getPointer();
81 static RValue getIgnored() {
82 // FIXME: should we make this a more explicit state?
86 static RValue get(llvm::Value *V) {
93 static RValue getComplex(llvm::Value *V1, llvm::Value *V2) {
97 ER.V1.setInt(Complex);
101 static RValue getComplex(const std::pair<llvm::Value *, llvm::Value *> &C) {
102 return getComplex(C.first, C.second);
104 // FIXME: Aggregate rvalues need to retain information about whether they are
105 // volatile or not. Remove default to find all places that probably get this
107 static RValue getAggregate(Address addr, bool isVolatile = false) {
109 ER.V1.setPointer(addr.getPointer());
110 ER.V1.setInt(Aggregate);
112 auto align = static_cast<uintptr_t>(addr.getAlignment().getQuantity());
113 ER.V2.setPointer(reinterpret_cast<llvm::Value*>(align << AggAlignShift));
114 ER.V2.setInt(isVolatile);
119 /// Does an ARC strong l-value have precise lifetime?
120 enum ARCPreciseLifetime_t {
121 ARCImpreciseLifetime, ARCPreciseLifetime
124 /// The source of the alignment of an l-value; an expression of
125 /// confidence in the alignment actually matching the estimate.
126 enum class AlignmentSource {
127 /// The l-value was an access to a declared entity or something
128 /// equivalently strong, like the address of an array allocated by a
129 /// language runtime.
132 /// The l-value was considered opaque, so the alignment was
133 /// determined from a type, but that type was an explicitly-aligned
137 /// The l-value was considered opaque, so the alignment was
138 /// determined from a type.
142 /// Given that the base address has the given alignment source, what's
143 /// our confidence in the alignment of the field?
144 static inline AlignmentSource getFieldAlignmentSource(AlignmentSource Source) {
145 // For now, we don't distinguish fields of opaque pointers from
146 // top-level declarations, but maybe we should.
147 return AlignmentSource::Decl;
150 class LValueBaseInfo {
151 AlignmentSource AlignSource;
154 explicit LValueBaseInfo(AlignmentSource Source = AlignmentSource::Type)
155 : AlignSource(Source) {}
156 AlignmentSource getAlignmentSource() const { return AlignSource; }
157 void setAlignmentSource(AlignmentSource Source) { AlignSource = Source; }
159 void mergeForCast(const LValueBaseInfo &Info) {
160 setAlignmentSource(Info.getAlignmentSource());
164 /// LValue - This represents an lvalue references. Because C/C++ allow
165 /// bitfields, this is not a simple LLVM pointer, it may be a pointer plus a
169 Simple, // This is a normal l-value, use getAddress().
170 VectorElt, // This is a vector element l-value (V[i]), use getVector*
171 BitField, // This is a bitfield l-value, use getBitfield*.
172 ExtVectorElt, // This is an extended vector subset, use getExtVectorComp
173 GlobalReg // This is a register l-value, use getGlobalReg()
179 // Index into a vector subscript: V[i]
180 llvm::Value *VectorIdx;
182 // ExtVector element subset: V.xyx
183 llvm::Constant *VectorElts;
185 // BitField start bit and size
186 const CGBitFieldInfo *BitFieldInfo;
191 // 'const' is unused here
194 // The alignment to use when accessing this lvalue. (For vector elements,
195 // this is the alignment of the whole vector.)
198 // objective-c's ivar
201 // objective-c's ivar is an array
204 // LValue is non-gc'able for any reason, including being a parameter or local
208 // Lvalue is a global reference of an objective-c object
209 bool GlobalObjCRef : 1;
211 // Lvalue is a thread local reference
212 bool ThreadLocalRef : 1;
214 // Lvalue has ARC imprecise lifetime. We store this inverted to try
215 // to make the default bitfield pattern all-zeroes.
216 bool ImpreciseLifetime : 1;
218 LValueBaseInfo BaseInfo;
219 TBAAAccessInfo TBAAInfo;
221 // This flag shows if a nontemporal load/stores should be used when accessing
223 bool Nontemporal : 1;
228 void Initialize(QualType Type, Qualifiers Quals, CharUnits Alignment,
229 LValueBaseInfo BaseInfo, TBAAAccessInfo TBAAInfo) {
230 assert((!Alignment.isZero() || Type->isIncompleteType()) &&
231 "initializing l-value with zero alignment!");
234 this->Alignment = Alignment.getQuantity();
235 assert(this->Alignment == Alignment.getQuantity() &&
236 "Alignment exceeds allowed max!");
237 this->BaseInfo = BaseInfo;
238 this->TBAAInfo = TBAAInfo;
240 // Initialize Objective-C flags.
241 this->Ivar = this->ObjIsArray = this->NonGC = this->GlobalObjCRef = false;
242 this->ImpreciseLifetime = false;
243 this->Nontemporal = false;
244 this->ThreadLocalRef = false;
245 this->BaseIvarExp = nullptr;
249 bool isSimple() const { return LVType == Simple; }
250 bool isVectorElt() const { return LVType == VectorElt; }
251 bool isBitField() const { return LVType == BitField; }
252 bool isExtVectorElt() const { return LVType == ExtVectorElt; }
253 bool isGlobalReg() const { return LVType == GlobalReg; }
255 bool isVolatileQualified() const { return Quals.hasVolatile(); }
256 bool isRestrictQualified() const { return Quals.hasRestrict(); }
257 unsigned getVRQualifiers() const {
258 return Quals.getCVRQualifiers() & ~Qualifiers::Const;
261 QualType getType() const { return Type; }
263 Qualifiers::ObjCLifetime getObjCLifetime() const {
264 return Quals.getObjCLifetime();
267 bool isObjCIvar() const { return Ivar; }
268 void setObjCIvar(bool Value) { Ivar = Value; }
270 bool isObjCArray() const { return ObjIsArray; }
271 void setObjCArray(bool Value) { ObjIsArray = Value; }
273 bool isNonGC () const { return NonGC; }
274 void setNonGC(bool Value) { NonGC = Value; }
276 bool isGlobalObjCRef() const { return GlobalObjCRef; }
277 void setGlobalObjCRef(bool Value) { GlobalObjCRef = Value; }
279 bool isThreadLocalRef() const { return ThreadLocalRef; }
280 void setThreadLocalRef(bool Value) { ThreadLocalRef = Value;}
282 ARCPreciseLifetime_t isARCPreciseLifetime() const {
283 return ARCPreciseLifetime_t(!ImpreciseLifetime);
285 void setARCPreciseLifetime(ARCPreciseLifetime_t value) {
286 ImpreciseLifetime = (value == ARCImpreciseLifetime);
288 bool isNontemporal() const { return Nontemporal; }
289 void setNontemporal(bool Value) { Nontemporal = Value; }
291 bool isObjCWeak() const {
292 return Quals.getObjCGCAttr() == Qualifiers::Weak;
294 bool isObjCStrong() const {
295 return Quals.getObjCGCAttr() == Qualifiers::Strong;
298 bool isVolatile() const {
299 return Quals.hasVolatile();
302 Expr *getBaseIvarExp() const { return BaseIvarExp; }
303 void setBaseIvarExp(Expr *V) { BaseIvarExp = V; }
305 TBAAAccessInfo getTBAAInfo() const { return TBAAInfo; }
306 void setTBAAInfo(TBAAAccessInfo Info) { TBAAInfo = Info; }
308 const Qualifiers &getQuals() const { return Quals; }
309 Qualifiers &getQuals() { return Quals; }
311 LangAS getAddressSpace() const { return Quals.getAddressSpace(); }
313 CharUnits getAlignment() const { return CharUnits::fromQuantity(Alignment); }
314 void setAlignment(CharUnits A) { Alignment = A.getQuantity(); }
316 LValueBaseInfo getBaseInfo() const { return BaseInfo; }
317 void setBaseInfo(LValueBaseInfo Info) { BaseInfo = Info; }
320 llvm::Value *getPointer() const {
324 Address getAddress() const { return Address(getPointer(), getAlignment()); }
325 void setAddress(Address address) {
327 V = address.getPointer();
328 Alignment = address.getAlignment().getQuantity();
332 Address getVectorAddress() const {
333 return Address(getVectorPointer(), getAlignment());
335 llvm::Value *getVectorPointer() const { assert(isVectorElt()); return V; }
336 llvm::Value *getVectorIdx() const { assert(isVectorElt()); return VectorIdx; }
338 // extended vector elements.
339 Address getExtVectorAddress() const {
340 return Address(getExtVectorPointer(), getAlignment());
342 llvm::Value *getExtVectorPointer() const {
343 assert(isExtVectorElt());
346 llvm::Constant *getExtVectorElts() const {
347 assert(isExtVectorElt());
352 Address getBitFieldAddress() const {
353 return Address(getBitFieldPointer(), getAlignment());
355 llvm::Value *getBitFieldPointer() const { assert(isBitField()); return V; }
356 const CGBitFieldInfo &getBitFieldInfo() const {
357 assert(isBitField());
358 return *BitFieldInfo;
361 // global register lvalue
362 llvm::Value *getGlobalReg() const { assert(isGlobalReg()); return V; }
364 static LValue MakeAddr(Address address, QualType type, ASTContext &Context,
365 LValueBaseInfo BaseInfo, TBAAAccessInfo TBAAInfo) {
366 Qualifiers qs = type.getQualifiers();
367 qs.setObjCGCAttr(Context.getObjCGCAttrKind(type));
371 assert(address.getPointer()->getType()->isPointerTy());
372 R.V = address.getPointer();
373 R.Initialize(type, qs, address.getAlignment(), BaseInfo, TBAAInfo);
377 static LValue MakeVectorElt(Address vecAddress, llvm::Value *Idx,
378 QualType type, LValueBaseInfo BaseInfo,
379 TBAAAccessInfo TBAAInfo) {
381 R.LVType = VectorElt;
382 R.V = vecAddress.getPointer();
384 R.Initialize(type, type.getQualifiers(), vecAddress.getAlignment(),
389 static LValue MakeExtVectorElt(Address vecAddress, llvm::Constant *Elts,
390 QualType type, LValueBaseInfo BaseInfo,
391 TBAAAccessInfo TBAAInfo) {
393 R.LVType = ExtVectorElt;
394 R.V = vecAddress.getPointer();
396 R.Initialize(type, type.getQualifiers(), vecAddress.getAlignment(),
401 /// \brief Create a new object to represent a bit-field access.
403 /// \param Addr - The base address of the bit-field sequence this
404 /// bit-field refers to.
405 /// \param Info - The information describing how to perform the bit-field
407 static LValue MakeBitfield(Address Addr, const CGBitFieldInfo &Info,
408 QualType type, LValueBaseInfo BaseInfo,
409 TBAAAccessInfo TBAAInfo) {
412 R.V = Addr.getPointer();
413 R.BitFieldInfo = &Info;
414 R.Initialize(type, type.getQualifiers(), Addr.getAlignment(), BaseInfo,
419 static LValue MakeGlobalReg(Address Reg, QualType type) {
421 R.LVType = GlobalReg;
422 R.V = Reg.getPointer();
423 R.Initialize(type, type.getQualifiers(), Reg.getAlignment(),
424 LValueBaseInfo(AlignmentSource::Decl), TBAAAccessInfo());
428 RValue asAggregateRValue() const {
429 return RValue::getAggregate(getAddress(), isVolatileQualified());
433 /// An aggregate value slot.
443 /// DestructedFlag - This is set to true if some external code is
444 /// responsible for setting up a destructor for the slot. Otherwise
445 /// the code which constructs it should push the appropriate cleanup.
446 bool DestructedFlag : 1;
448 /// ObjCGCFlag - This is set to true if writing to the memory in the
449 /// slot might require calling an appropriate Objective-C GC
450 /// barrier. The exact interaction here is unnecessarily mysterious.
453 /// ZeroedFlag - This is set to true if the memory in the slot is
454 /// known to be zero before the assignment into it. This means that
455 /// zero fields don't need to be set.
458 /// AliasedFlag - This is set to true if the slot might be aliased
459 /// and it's not undefined behavior to access it through such an
460 /// alias. Note that it's always undefined behavior to access a C++
461 /// object that's under construction through an alias derived from
462 /// outside the construction process.
464 /// This flag controls whether calls that produce the aggregate
465 /// value may be evaluated directly into the slot, or whether they
466 /// must be evaluated into an unaliased temporary and then memcpy'ed
467 /// over. Since it's invalid in general to memcpy a non-POD C++
468 /// object, it's important that this flag never be set when
469 /// evaluating an expression which constructs such an object.
470 bool AliasedFlag : 1;
473 enum IsAliased_t { IsNotAliased, IsAliased };
474 enum IsDestructed_t { IsNotDestructed, IsDestructed };
475 enum IsZeroed_t { IsNotZeroed, IsZeroed };
476 enum NeedsGCBarriers_t { DoesNotNeedGCBarriers, NeedsGCBarriers };
478 /// ignored - Returns an aggregate value slot indicating that the
479 /// aggregate value is being ignored.
480 static AggValueSlot ignored() {
481 return forAddr(Address::invalid(), Qualifiers(), IsNotDestructed,
482 DoesNotNeedGCBarriers, IsNotAliased);
485 /// forAddr - Make a slot for an aggregate value.
487 /// \param quals - The qualifiers that dictate how the slot should
488 /// be initialied. Only 'volatile' and the Objective-C lifetime
489 /// qualifiers matter.
491 /// \param isDestructed - true if something else is responsible
492 /// for calling destructors on this object
493 /// \param needsGC - true if the slot is potentially located
494 /// somewhere that ObjC GC calls should be emitted for
495 static AggValueSlot forAddr(Address addr,
497 IsDestructed_t isDestructed,
498 NeedsGCBarriers_t needsGC,
499 IsAliased_t isAliased,
500 IsZeroed_t isZeroed = IsNotZeroed) {
502 if (addr.isValid()) {
503 AV.Addr = addr.getPointer();
504 AV.Alignment = addr.getAlignment().getQuantity();
510 AV.DestructedFlag = isDestructed;
511 AV.ObjCGCFlag = needsGC;
512 AV.ZeroedFlag = isZeroed;
513 AV.AliasedFlag = isAliased;
517 static AggValueSlot forLValue(const LValue &LV,
518 IsDestructed_t isDestructed,
519 NeedsGCBarriers_t needsGC,
520 IsAliased_t isAliased,
521 IsZeroed_t isZeroed = IsNotZeroed) {
522 return forAddr(LV.getAddress(),
523 LV.getQuals(), isDestructed, needsGC, isAliased, isZeroed);
526 IsDestructed_t isExternallyDestructed() const {
527 return IsDestructed_t(DestructedFlag);
529 void setExternallyDestructed(bool destructed = true) {
530 DestructedFlag = destructed;
533 Qualifiers getQualifiers() const { return Quals; }
535 bool isVolatile() const {
536 return Quals.hasVolatile();
539 void setVolatile(bool flag) {
540 Quals.setVolatile(flag);
543 Qualifiers::ObjCLifetime getObjCLifetime() const {
544 return Quals.getObjCLifetime();
547 NeedsGCBarriers_t requiresGCollection() const {
548 return NeedsGCBarriers_t(ObjCGCFlag);
551 llvm::Value *getPointer() const {
555 Address getAddress() const {
556 return Address(Addr, getAlignment());
559 bool isIgnored() const {
560 return Addr == nullptr;
563 CharUnits getAlignment() const {
564 return CharUnits::fromQuantity(Alignment);
567 IsAliased_t isPotentiallyAliased() const {
568 return IsAliased_t(AliasedFlag);
571 RValue asRValue() const {
573 return RValue::getIgnored();
575 return RValue::getAggregate(getAddress(), isVolatile());
579 void setZeroed(bool V = true) { ZeroedFlag = V; }
580 IsZeroed_t isZeroed() const {
581 return IsZeroed_t(ZeroedFlag);
585 } // end namespace CodeGen
586 } // end namespace clang