1//===-- CGValue.h - LLVM CodeGen wrappers for llvm::Value* ------*- C++ -*-===//
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// These classes implement wrappers around llvm::Value in order to
11// fully represent the range of values for C L- and R- values.
12//
13//===----------------------------------------------------------------------===//
14
15#ifndef CLANG_CODEGEN_CGVALUE_H
16#define CLANG_CODEGEN_CGVALUE_H
17
18#include "clang/AST/ASTContext.h"
19#include "clang/AST/CharUnits.h"
20#include "clang/AST/Type.h"
21#include "llvm/IR/Value.h"
22
23namespace llvm {
24  class Constant;
25  class MDNode;
26}
27
28namespace clang {
29namespace CodeGen {
30  class AggValueSlot;
31  struct CGBitFieldInfo;
32
33/// RValue - This trivial value class is used to represent the result of an
34/// expression that is evaluated.  It can be one of three things: either a
35/// simple LLVM SSA value, a pair of SSA values for complex numbers, or the
36/// address of an aggregate value in memory.
37class RValue {
38  enum Flavor { Scalar, Complex, Aggregate };
39
40  // Stores first value and flavor.
41  llvm::PointerIntPair<llvm::Value *, 2, Flavor> V1;
42  // Stores second value and volatility.
43  llvm::PointerIntPair<llvm::Value *, 1, bool> V2;
44
45public:
46  bool isScalar() const { return V1.getInt() == Scalar; }
47  bool isComplex() const { return V1.getInt() == Complex; }
48  bool isAggregate() const { return V1.getInt() == Aggregate; }
49
50  bool isVolatileQualified() const { return V2.getInt(); }
51
52  /// getScalarVal() - Return the Value* of this scalar value.
53  llvm::Value *getScalarVal() const {
54    assert(isScalar() && "Not a scalar!");
55    return V1.getPointer();
56  }
57
58  /// getComplexVal - Return the real/imag components of this complex value.
59  ///
60  std::pair<llvm::Value *, llvm::Value *> getComplexVal() const {
61    return std::make_pair(V1.getPointer(), V2.getPointer());
62  }
63
64  /// getAggregateAddr() - Return the Value* of the address of the aggregate.
65  llvm::Value *getAggregateAddr() const {
66    assert(isAggregate() && "Not an aggregate!");
67    return V1.getPointer();
68  }
69
70  static RValue get(llvm::Value *V) {
71    RValue ER;
72    ER.V1.setPointer(V);
73    ER.V1.setInt(Scalar);
74    ER.V2.setInt(false);
75    return ER;
76  }
77  static RValue getComplex(llvm::Value *V1, llvm::Value *V2) {
78    RValue ER;
79    ER.V1.setPointer(V1);
80    ER.V2.setPointer(V2);
81    ER.V1.setInt(Complex);
82    ER.V2.setInt(false);
83    return ER;
84  }
85  static RValue getComplex(const std::pair<llvm::Value *, llvm::Value *> &C) {
86    return getComplex(C.first, C.second);
87  }
88  // FIXME: Aggregate rvalues need to retain information about whether they are
89  // volatile or not.  Remove default to find all places that probably get this
90  // wrong.
91  static RValue getAggregate(llvm::Value *V, bool Volatile = false) {
92    RValue ER;
93    ER.V1.setPointer(V);
94    ER.V1.setInt(Aggregate);
95    ER.V2.setInt(Volatile);
96    return ER;
97  }
98};
99
100/// Does an ARC strong l-value have precise lifetime?
101enum ARCPreciseLifetime_t {
102  ARCImpreciseLifetime, ARCPreciseLifetime
103};
104
105/// LValue - This represents an lvalue references.  Because C/C++ allow
106/// bitfields, this is not a simple LLVM pointer, it may be a pointer plus a
107/// bitrange.
108class LValue {
109  enum {
110    Simple,       // This is a normal l-value, use getAddress().
111    VectorElt,    // This is a vector element l-value (V[i]), use getVector*
112    BitField,     // This is a bitfield l-value, use getBitfield*.
113    ExtVectorElt  // This is an extended vector subset, use getExtVectorComp
114  } LVType;
115
116  llvm::Value *V;
117
118  union {
119    // Index into a vector subscript: V[i]
120    llvm::Value *VectorIdx;
121
122    // ExtVector element subset: V.xyx
123    llvm::Constant *VectorElts;
124
125    // BitField start bit and size
126    const CGBitFieldInfo *BitFieldInfo;
127  };
128
129  QualType Type;
130
131  // 'const' is unused here
132  Qualifiers Quals;
133
134  // The alignment to use when accessing this lvalue.  (For vector elements,
135  // this is the alignment of the whole vector.)
136  int64_t Alignment;
137
138  // objective-c's ivar
139  bool Ivar:1;
140
141  // objective-c's ivar is an array
142  bool ObjIsArray:1;
143
144  // LValue is non-gc'able for any reason, including being a parameter or local
145  // variable.
146  bool NonGC: 1;
147
148  // Lvalue is a global reference of an objective-c object
149  bool GlobalObjCRef : 1;
150
151  // Lvalue is a thread local reference
152  bool ThreadLocalRef : 1;
153
154  // Lvalue has ARC imprecise lifetime.  We store this inverted to try
155  // to make the default bitfield pattern all-zeroes.
156  bool ImpreciseLifetime : 1;
157
158  Expr *BaseIvarExp;
159
160  /// Used by struct-path-aware TBAA.
161  QualType TBAABaseType;
162  /// Offset relative to the base type.
163  uint64_t TBAAOffset;
164
165  /// TBAAInfo - TBAA information to attach to dereferences of this LValue.
166  llvm::MDNode *TBAAInfo;
167
168private:
169  void Initialize(QualType Type, Qualifiers Quals,
170                  CharUnits Alignment,
171                  llvm::MDNode *TBAAInfo = 0) {
172    this->Type = Type;
173    this->Quals = Quals;
174    this->Alignment = Alignment.getQuantity();
175    assert(this->Alignment == Alignment.getQuantity() &&
176           "Alignment exceeds allowed max!");
177
178    // Initialize Objective-C flags.
179    this->Ivar = this->ObjIsArray = this->NonGC = this->GlobalObjCRef = false;
180    this->ImpreciseLifetime = false;
181    this->ThreadLocalRef = false;
182    this->BaseIvarExp = 0;
183
184    // Initialize fields for TBAA.
185    this->TBAABaseType = Type;
186    this->TBAAOffset = 0;
187    this->TBAAInfo = TBAAInfo;
188  }
189
190public:
191  bool isSimple() const { return LVType == Simple; }
192  bool isVectorElt() const { return LVType == VectorElt; }
193  bool isBitField() const { return LVType == BitField; }
194  bool isExtVectorElt() const { return LVType == ExtVectorElt; }
195
196  bool isVolatileQualified() const { return Quals.hasVolatile(); }
197  bool isRestrictQualified() const { return Quals.hasRestrict(); }
198  unsigned getVRQualifiers() const {
199    return Quals.getCVRQualifiers() & ~Qualifiers::Const;
200  }
201
202  QualType getType() const { return Type; }
203
204  Qualifiers::ObjCLifetime getObjCLifetime() const {
205    return Quals.getObjCLifetime();
206  }
207
208  bool isObjCIvar() const { return Ivar; }
209  void setObjCIvar(bool Value) { Ivar = Value; }
210
211  bool isObjCArray() const { return ObjIsArray; }
212  void setObjCArray(bool Value) { ObjIsArray = Value; }
213
214  bool isNonGC () const { return NonGC; }
215  void setNonGC(bool Value) { NonGC = Value; }
216
217  bool isGlobalObjCRef() const { return GlobalObjCRef; }
218  void setGlobalObjCRef(bool Value) { GlobalObjCRef = Value; }
219
220  bool isThreadLocalRef() const { return ThreadLocalRef; }
221  void setThreadLocalRef(bool Value) { ThreadLocalRef = Value;}
222
223  ARCPreciseLifetime_t isARCPreciseLifetime() const {
224    return ARCPreciseLifetime_t(!ImpreciseLifetime);
225  }
226  void setARCPreciseLifetime(ARCPreciseLifetime_t value) {
227    ImpreciseLifetime = (value == ARCImpreciseLifetime);
228  }
229
230  bool isObjCWeak() const {
231    return Quals.getObjCGCAttr() == Qualifiers::Weak;
232  }
233  bool isObjCStrong() const {
234    return Quals.getObjCGCAttr() == Qualifiers::Strong;
235  }
236
237  bool isVolatile() const {
238    return Quals.hasVolatile();
239  }
240
241  Expr *getBaseIvarExp() const { return BaseIvarExp; }
242  void setBaseIvarExp(Expr *V) { BaseIvarExp = V; }
243
244  QualType getTBAABaseType() const { return TBAABaseType; }
245  void setTBAABaseType(QualType T) { TBAABaseType = T; }
246
247  uint64_t getTBAAOffset() const { return TBAAOffset; }
248  void setTBAAOffset(uint64_t O) { TBAAOffset = O; }
249
250  llvm::MDNode *getTBAAInfo() const { return TBAAInfo; }
251  void setTBAAInfo(llvm::MDNode *N) { TBAAInfo = N; }
252
253  const Qualifiers &getQuals() const { return Quals; }
254  Qualifiers &getQuals() { return Quals; }
255
256  unsigned getAddressSpace() const { return Quals.getAddressSpace(); }
257
258  CharUnits getAlignment() const { return CharUnits::fromQuantity(Alignment); }
259  void setAlignment(CharUnits A) { Alignment = A.getQuantity(); }
260
261  // simple lvalue
262  llvm::Value *getAddress() const { assert(isSimple()); return V; }
263  void setAddress(llvm::Value *address) {
264    assert(isSimple());
265    V = address;
266  }
267
268  // vector elt lvalue
269  llvm::Value *getVectorAddr() const { assert(isVectorElt()); return V; }
270  llvm::Value *getVectorIdx() const { assert(isVectorElt()); return VectorIdx; }
271
272  // extended vector elements.
273  llvm::Value *getExtVectorAddr() const { assert(isExtVectorElt()); return V; }
274  llvm::Constant *getExtVectorElts() const {
275    assert(isExtVectorElt());
276    return VectorElts;
277  }
278
279  // bitfield lvalue
280  llvm::Value *getBitFieldAddr() const {
281    assert(isBitField());
282    return V;
283  }
284  const CGBitFieldInfo &getBitFieldInfo() const {
285    assert(isBitField());
286    return *BitFieldInfo;
287  }
288
289  static LValue MakeAddr(llvm::Value *address, QualType type,
290                         CharUnits alignment, ASTContext &Context,
291                         llvm::MDNode *TBAAInfo = 0) {
292    Qualifiers qs = type.getQualifiers();
293    qs.setObjCGCAttr(Context.getObjCGCAttrKind(type));
294
295    LValue R;
296    R.LVType = Simple;
297    R.V = address;
298    R.Initialize(type, qs, alignment, TBAAInfo);
299    return R;
300  }
301
302  static LValue MakeVectorElt(llvm::Value *Vec, llvm::Value *Idx,
303                              QualType type, CharUnits Alignment) {
304    LValue R;
305    R.LVType = VectorElt;
306    R.V = Vec;
307    R.VectorIdx = Idx;
308    R.Initialize(type, type.getQualifiers(), Alignment);
309    return R;
310  }
311
312  static LValue MakeExtVectorElt(llvm::Value *Vec, llvm::Constant *Elts,
313                                 QualType type, CharUnits Alignment) {
314    LValue R;
315    R.LVType = ExtVectorElt;
316    R.V = Vec;
317    R.VectorElts = Elts;
318    R.Initialize(type, type.getQualifiers(), Alignment);
319    return R;
320  }
321
322  /// \brief Create a new object to represent a bit-field access.
323  ///
324  /// \param Addr - The base address of the bit-field sequence this
325  /// bit-field refers to.
326  /// \param Info - The information describing how to perform the bit-field
327  /// access.
328  static LValue MakeBitfield(llvm::Value *Addr,
329                             const CGBitFieldInfo &Info,
330                             QualType type, CharUnits Alignment) {
331    LValue R;
332    R.LVType = BitField;
333    R.V = Addr;
334    R.BitFieldInfo = &Info;
335    R.Initialize(type, type.getQualifiers(), Alignment);
336    return R;
337  }
338
339  RValue asAggregateRValue() const {
340    // FIMXE: Alignment
341    return RValue::getAggregate(getAddress(), isVolatileQualified());
342  }
343};
344
345/// An aggregate value slot.
346class AggValueSlot {
347  /// The address.
348  llvm::Value *Addr;
349
350  // Qualifiers
351  Qualifiers Quals;
352
353  unsigned short Alignment;
354
355  /// DestructedFlag - This is set to true if some external code is
356  /// responsible for setting up a destructor for the slot.  Otherwise
357  /// the code which constructs it should push the appropriate cleanup.
358  bool DestructedFlag : 1;
359
360  /// ObjCGCFlag - This is set to true if writing to the memory in the
361  /// slot might require calling an appropriate Objective-C GC
362  /// barrier.  The exact interaction here is unnecessarily mysterious.
363  bool ObjCGCFlag : 1;
364
365  /// ZeroedFlag - This is set to true if the memory in the slot is
366  /// known to be zero before the assignment into it.  This means that
367  /// zero fields don't need to be set.
368  bool ZeroedFlag : 1;
369
370  /// AliasedFlag - This is set to true if the slot might be aliased
371  /// and it's not undefined behavior to access it through such an
372  /// alias.  Note that it's always undefined behavior to access a C++
373  /// object that's under construction through an alias derived from
374  /// outside the construction process.
375  ///
376  /// This flag controls whether calls that produce the aggregate
377  /// value may be evaluated directly into the slot, or whether they
378  /// must be evaluated into an unaliased temporary and then memcpy'ed
379  /// over.  Since it's invalid in general to memcpy a non-POD C++
380  /// object, it's important that this flag never be set when
381  /// evaluating an expression which constructs such an object.
382  bool AliasedFlag : 1;
383
384public:
385  enum IsAliased_t { IsNotAliased, IsAliased };
386  enum IsDestructed_t { IsNotDestructed, IsDestructed };
387  enum IsZeroed_t { IsNotZeroed, IsZeroed };
388  enum NeedsGCBarriers_t { DoesNotNeedGCBarriers, NeedsGCBarriers };
389
390  /// ignored - Returns an aggregate value slot indicating that the
391  /// aggregate value is being ignored.
392  static AggValueSlot ignored() {
393    return forAddr(0, CharUnits(), Qualifiers(), IsNotDestructed,
394                   DoesNotNeedGCBarriers, IsNotAliased);
395  }
396
397  /// forAddr - Make a slot for an aggregate value.
398  ///
399  /// \param quals - The qualifiers that dictate how the slot should
400  /// be initialied. Only 'volatile' and the Objective-C lifetime
401  /// qualifiers matter.
402  ///
403  /// \param isDestructed - true if something else is responsible
404  ///   for calling destructors on this object
405  /// \param needsGC - true if the slot is potentially located
406  ///   somewhere that ObjC GC calls should be emitted for
407  static AggValueSlot forAddr(llvm::Value *addr, CharUnits align,
408                              Qualifiers quals,
409                              IsDestructed_t isDestructed,
410                              NeedsGCBarriers_t needsGC,
411                              IsAliased_t isAliased,
412                              IsZeroed_t isZeroed = IsNotZeroed) {
413    AggValueSlot AV;
414    AV.Addr = addr;
415    AV.Alignment = align.getQuantity();
416    AV.Quals = quals;
417    AV.DestructedFlag = isDestructed;
418    AV.ObjCGCFlag = needsGC;
419    AV.ZeroedFlag = isZeroed;
420    AV.AliasedFlag = isAliased;
421    return AV;
422  }
423
424  static AggValueSlot forLValue(const LValue &LV,
425                                IsDestructed_t isDestructed,
426                                NeedsGCBarriers_t needsGC,
427                                IsAliased_t isAliased,
428                                IsZeroed_t isZeroed = IsNotZeroed) {
429    return forAddr(LV.getAddress(), LV.getAlignment(),
430                   LV.getQuals(), isDestructed, needsGC, isAliased, isZeroed);
431  }
432
433  IsDestructed_t isExternallyDestructed() const {
434    return IsDestructed_t(DestructedFlag);
435  }
436  void setExternallyDestructed(bool destructed = true) {
437    DestructedFlag = destructed;
438  }
439
440  Qualifiers getQualifiers() const { return Quals; }
441
442  bool isVolatile() const {
443    return Quals.hasVolatile();
444  }
445
446  void setVolatile(bool flag) {
447    Quals.setVolatile(flag);
448  }
449
450  Qualifiers::ObjCLifetime getObjCLifetime() const {
451    return Quals.getObjCLifetime();
452  }
453
454  NeedsGCBarriers_t requiresGCollection() const {
455    return NeedsGCBarriers_t(ObjCGCFlag);
456  }
457
458  llvm::Value *getAddr() const {
459    return Addr;
460  }
461
462  bool isIgnored() const {
463    return Addr == 0;
464  }
465
466  CharUnits getAlignment() const {
467    return CharUnits::fromQuantity(Alignment);
468  }
469
470  IsAliased_t isPotentiallyAliased() const {
471    return IsAliased_t(AliasedFlag);
472  }
473
474  // FIXME: Alignment?
475  RValue asRValue() const {
476    return RValue::getAggregate(getAddr(), isVolatile());
477  }
478
479  void setZeroed(bool V = true) { ZeroedFlag = V; }
480  IsZeroed_t isZeroed() const {
481    return IsZeroed_t(ZeroedFlag);
482  }
483};
484
485}  // end namespace CodeGen
486}  // end namespace clang
487
488#endif
489