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 LLVM_CLANG_LIB_CODEGEN_CGVALUE_H
16#define LLVM_CLANG_LIB_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#include "llvm/IR/Type.h"
23
24namespace llvm {
25  class Constant;
26  class MDNode;
27}
28
29namespace clang {
30namespace CodeGen {
31  class AggValueSlot;
32  struct CGBitFieldInfo;
33
34/// RValue - This trivial value class is used to represent the result of an
35/// expression that is evaluated.  It can be one of three things: either a
36/// simple LLVM SSA value, a pair of SSA values for complex numbers, or the
37/// address of an aggregate value in memory.
38class RValue {
39  enum Flavor { Scalar, Complex, Aggregate };
40
41  // Stores first value and flavor.
42  llvm::PointerIntPair<llvm::Value *, 2, Flavor> V1;
43  // Stores second value and volatility.
44  llvm::PointerIntPair<llvm::Value *, 1, bool> V2;
45
46public:
47  bool isScalar() const { return V1.getInt() == Scalar; }
48  bool isComplex() const { return V1.getInt() == Complex; }
49  bool isAggregate() const { return V1.getInt() == Aggregate; }
50
51  bool isVolatileQualified() const { return V2.getInt(); }
52
53  /// getScalarVal() - Return the Value* of this scalar value.
54  llvm::Value *getScalarVal() const {
55    assert(isScalar() && "Not a scalar!");
56    return V1.getPointer();
57  }
58
59  /// getComplexVal - Return the real/imag components of this complex value.
60  ///
61  std::pair<llvm::Value *, llvm::Value *> getComplexVal() const {
62    return std::make_pair(V1.getPointer(), V2.getPointer());
63  }
64
65  /// getAggregateAddr() - Return the Value* of the address of the aggregate.
66  llvm::Value *getAggregateAddr() const {
67    assert(isAggregate() && "Not an aggregate!");
68    return V1.getPointer();
69  }
70
71  static RValue get(llvm::Value *V) {
72    RValue ER;
73    ER.V1.setPointer(V);
74    ER.V1.setInt(Scalar);
75    ER.V2.setInt(false);
76    return ER;
77  }
78  static RValue getComplex(llvm::Value *V1, llvm::Value *V2) {
79    RValue ER;
80    ER.V1.setPointer(V1);
81    ER.V2.setPointer(V2);
82    ER.V1.setInt(Complex);
83    ER.V2.setInt(false);
84    return ER;
85  }
86  static RValue getComplex(const std::pair<llvm::Value *, llvm::Value *> &C) {
87    return getComplex(C.first, C.second);
88  }
89  // FIXME: Aggregate rvalues need to retain information about whether they are
90  // volatile or not.  Remove default to find all places that probably get this
91  // wrong.
92  static RValue getAggregate(llvm::Value *V, bool Volatile = false) {
93    RValue ER;
94    ER.V1.setPointer(V);
95    ER.V1.setInt(Aggregate);
96    ER.V2.setInt(Volatile);
97    return ER;
98  }
99};
100
101/// Does an ARC strong l-value have precise lifetime?
102enum ARCPreciseLifetime_t {
103  ARCImpreciseLifetime, ARCPreciseLifetime
104};
105
106/// LValue - This represents an lvalue references.  Because C/C++ allow
107/// bitfields, this is not a simple LLVM pointer, it may be a pointer plus a
108/// bitrange.
109class LValue {
110  enum {
111    Simple,       // This is a normal l-value, use getAddress().
112    VectorElt,    // This is a vector element l-value (V[i]), use getVector*
113    BitField,     // This is a bitfield l-value, use getBitfield*.
114    ExtVectorElt, // This is an extended vector subset, use getExtVectorComp
115    GlobalReg     // This is a register l-value, use getGlobalReg()
116  } LVType;
117
118  llvm::Value *V;
119
120  union {
121    // Index into a vector subscript: V[i]
122    llvm::Value *VectorIdx;
123
124    // ExtVector element subset: V.xyx
125    llvm::Constant *VectorElts;
126
127    // BitField start bit and size
128    const CGBitFieldInfo *BitFieldInfo;
129  };
130
131  QualType Type;
132
133  // 'const' is unused here
134  Qualifiers Quals;
135
136  // The alignment to use when accessing this lvalue.  (For vector elements,
137  // this is the alignment of the whole vector.)
138  int64_t Alignment;
139
140  // objective-c's ivar
141  bool Ivar:1;
142
143  // objective-c's ivar is an array
144  bool ObjIsArray:1;
145
146  // LValue is non-gc'able for any reason, including being a parameter or local
147  // variable.
148  bool NonGC: 1;
149
150  // Lvalue is a global reference of an objective-c object
151  bool GlobalObjCRef : 1;
152
153  // Lvalue is a thread local reference
154  bool ThreadLocalRef : 1;
155
156  // Lvalue has ARC imprecise lifetime.  We store this inverted to try
157  // to make the default bitfield pattern all-zeroes.
158  bool ImpreciseLifetime : 1;
159
160  Expr *BaseIvarExp;
161
162  /// Used by struct-path-aware TBAA.
163  QualType TBAABaseType;
164  /// Offset relative to the base type.
165  uint64_t TBAAOffset;
166
167  /// TBAAInfo - TBAA information to attach to dereferences of this LValue.
168  llvm::MDNode *TBAAInfo;
169
170private:
171  void Initialize(QualType Type, Qualifiers Quals,
172                  CharUnits Alignment,
173                  llvm::MDNode *TBAAInfo = nullptr) {
174    this->Type = Type;
175    this->Quals = Quals;
176    this->Alignment = Alignment.getQuantity();
177    assert(this->Alignment == Alignment.getQuantity() &&
178           "Alignment exceeds allowed max!");
179
180    // Initialize Objective-C flags.
181    this->Ivar = this->ObjIsArray = this->NonGC = this->GlobalObjCRef = false;
182    this->ImpreciseLifetime = false;
183    this->ThreadLocalRef = false;
184    this->BaseIvarExp = nullptr;
185
186    // Initialize fields for TBAA.
187    this->TBAABaseType = Type;
188    this->TBAAOffset = 0;
189    this->TBAAInfo = TBAAInfo;
190  }
191
192public:
193  bool isSimple() const { return LVType == Simple; }
194  bool isVectorElt() const { return LVType == VectorElt; }
195  bool isBitField() const { return LVType == BitField; }
196  bool isExtVectorElt() const { return LVType == ExtVectorElt; }
197  bool isGlobalReg() const { return LVType == GlobalReg; }
198
199  bool isVolatileQualified() const { return Quals.hasVolatile(); }
200  bool isRestrictQualified() const { return Quals.hasRestrict(); }
201  unsigned getVRQualifiers() const {
202    return Quals.getCVRQualifiers() & ~Qualifiers::Const;
203  }
204
205  QualType getType() const { return Type; }
206
207  Qualifiers::ObjCLifetime getObjCLifetime() const {
208    return Quals.getObjCLifetime();
209  }
210
211  bool isObjCIvar() const { return Ivar; }
212  void setObjCIvar(bool Value) { Ivar = Value; }
213
214  bool isObjCArray() const { return ObjIsArray; }
215  void setObjCArray(bool Value) { ObjIsArray = Value; }
216
217  bool isNonGC () const { return NonGC; }
218  void setNonGC(bool Value) { NonGC = Value; }
219
220  bool isGlobalObjCRef() const { return GlobalObjCRef; }
221  void setGlobalObjCRef(bool Value) { GlobalObjCRef = Value; }
222
223  bool isThreadLocalRef() const { return ThreadLocalRef; }
224  void setThreadLocalRef(bool Value) { ThreadLocalRef = Value;}
225
226  ARCPreciseLifetime_t isARCPreciseLifetime() const {
227    return ARCPreciseLifetime_t(!ImpreciseLifetime);
228  }
229  void setARCPreciseLifetime(ARCPreciseLifetime_t value) {
230    ImpreciseLifetime = (value == ARCImpreciseLifetime);
231  }
232
233  bool isObjCWeak() const {
234    return Quals.getObjCGCAttr() == Qualifiers::Weak;
235  }
236  bool isObjCStrong() const {
237    return Quals.getObjCGCAttr() == Qualifiers::Strong;
238  }
239
240  bool isVolatile() const {
241    return Quals.hasVolatile();
242  }
243
244  Expr *getBaseIvarExp() const { return BaseIvarExp; }
245  void setBaseIvarExp(Expr *V) { BaseIvarExp = V; }
246
247  QualType getTBAABaseType() const { return TBAABaseType; }
248  void setTBAABaseType(QualType T) { TBAABaseType = T; }
249
250  uint64_t getTBAAOffset() const { return TBAAOffset; }
251  void setTBAAOffset(uint64_t O) { TBAAOffset = O; }
252
253  llvm::MDNode *getTBAAInfo() const { return TBAAInfo; }
254  void setTBAAInfo(llvm::MDNode *N) { TBAAInfo = N; }
255
256  const Qualifiers &getQuals() const { return Quals; }
257  Qualifiers &getQuals() { return Quals; }
258
259  unsigned getAddressSpace() const { return Quals.getAddressSpace(); }
260
261  CharUnits getAlignment() const { return CharUnits::fromQuantity(Alignment); }
262  void setAlignment(CharUnits A) { Alignment = A.getQuantity(); }
263
264  // simple lvalue
265  llvm::Value *getAddress() const { assert(isSimple()); return V; }
266  void setAddress(llvm::Value *address) {
267    assert(isSimple());
268    V = address;
269  }
270
271  // vector elt lvalue
272  llvm::Value *getVectorAddr() const { assert(isVectorElt()); return V; }
273  llvm::Value *getVectorIdx() const { assert(isVectorElt()); return VectorIdx; }
274
275  // extended vector elements.
276  llvm::Value *getExtVectorAddr() const { assert(isExtVectorElt()); return V; }
277  llvm::Constant *getExtVectorElts() const {
278    assert(isExtVectorElt());
279    return VectorElts;
280  }
281
282  // bitfield lvalue
283  llvm::Value *getBitFieldAddr() const {
284    assert(isBitField());
285    return V;
286  }
287  const CGBitFieldInfo &getBitFieldInfo() const {
288    assert(isBitField());
289    return *BitFieldInfo;
290  }
291
292  // global register lvalue
293  llvm::Value *getGlobalReg() const { assert(isGlobalReg()); return V; }
294
295  static LValue MakeAddr(llvm::Value *address, QualType type,
296                         CharUnits alignment, ASTContext &Context,
297                         llvm::MDNode *TBAAInfo = nullptr) {
298    Qualifiers qs = type.getQualifiers();
299    qs.setObjCGCAttr(Context.getObjCGCAttrKind(type));
300
301    LValue R;
302    R.LVType = Simple;
303    assert(address->getType()->isPointerTy());
304    R.V = address;
305    R.Initialize(type, qs, alignment, TBAAInfo);
306    return R;
307  }
308
309  static LValue MakeVectorElt(llvm::Value *Vec, llvm::Value *Idx,
310                              QualType type, CharUnits Alignment) {
311    LValue R;
312    R.LVType = VectorElt;
313    R.V = Vec;
314    R.VectorIdx = Idx;
315    R.Initialize(type, type.getQualifiers(), Alignment);
316    return R;
317  }
318
319  static LValue MakeExtVectorElt(llvm::Value *Vec, llvm::Constant *Elts,
320                                 QualType type, CharUnits Alignment) {
321    LValue R;
322    R.LVType = ExtVectorElt;
323    R.V = Vec;
324    R.VectorElts = Elts;
325    R.Initialize(type, type.getQualifiers(), Alignment);
326    return R;
327  }
328
329  /// \brief Create a new object to represent a bit-field access.
330  ///
331  /// \param Addr - The base address of the bit-field sequence this
332  /// bit-field refers to.
333  /// \param Info - The information describing how to perform the bit-field
334  /// access.
335  static LValue MakeBitfield(llvm::Value *Addr,
336                             const CGBitFieldInfo &Info,
337                             QualType type, CharUnits Alignment) {
338    LValue R;
339    R.LVType = BitField;
340    R.V = Addr;
341    R.BitFieldInfo = &Info;
342    R.Initialize(type, type.getQualifiers(), Alignment);
343    return R;
344  }
345
346  static LValue MakeGlobalReg(llvm::Value *Reg,
347                              QualType type,
348                              CharUnits Alignment) {
349    LValue R;
350    R.LVType = GlobalReg;
351    R.V = Reg;
352    R.Initialize(type, type.getQualifiers(), Alignment);
353    return R;
354  }
355
356  RValue asAggregateRValue() const {
357    // FIMXE: Alignment
358    return RValue::getAggregate(getAddress(), isVolatileQualified());
359  }
360};
361
362/// An aggregate value slot.
363class AggValueSlot {
364  /// The address.
365  llvm::Value *Addr;
366
367  // Qualifiers
368  Qualifiers Quals;
369
370  unsigned short Alignment;
371
372  /// DestructedFlag - This is set to true if some external code is
373  /// responsible for setting up a destructor for the slot.  Otherwise
374  /// the code which constructs it should push the appropriate cleanup.
375  bool DestructedFlag : 1;
376
377  /// ObjCGCFlag - This is set to true if writing to the memory in the
378  /// slot might require calling an appropriate Objective-C GC
379  /// barrier.  The exact interaction here is unnecessarily mysterious.
380  bool ObjCGCFlag : 1;
381
382  /// ZeroedFlag - This is set to true if the memory in the slot is
383  /// known to be zero before the assignment into it.  This means that
384  /// zero fields don't need to be set.
385  bool ZeroedFlag : 1;
386
387  /// AliasedFlag - This is set to true if the slot might be aliased
388  /// and it's not undefined behavior to access it through such an
389  /// alias.  Note that it's always undefined behavior to access a C++
390  /// object that's under construction through an alias derived from
391  /// outside the construction process.
392  ///
393  /// This flag controls whether calls that produce the aggregate
394  /// value may be evaluated directly into the slot, or whether they
395  /// must be evaluated into an unaliased temporary and then memcpy'ed
396  /// over.  Since it's invalid in general to memcpy a non-POD C++
397  /// object, it's important that this flag never be set when
398  /// evaluating an expression which constructs such an object.
399  bool AliasedFlag : 1;
400
401public:
402  enum IsAliased_t { IsNotAliased, IsAliased };
403  enum IsDestructed_t { IsNotDestructed, IsDestructed };
404  enum IsZeroed_t { IsNotZeroed, IsZeroed };
405  enum NeedsGCBarriers_t { DoesNotNeedGCBarriers, NeedsGCBarriers };
406
407  /// ignored - Returns an aggregate value slot indicating that the
408  /// aggregate value is being ignored.
409  static AggValueSlot ignored() {
410    return forAddr(nullptr, CharUnits(), Qualifiers(), IsNotDestructed,
411                   DoesNotNeedGCBarriers, IsNotAliased);
412  }
413
414  /// forAddr - Make a slot for an aggregate value.
415  ///
416  /// \param quals - The qualifiers that dictate how the slot should
417  /// be initialied. Only 'volatile' and the Objective-C lifetime
418  /// qualifiers matter.
419  ///
420  /// \param isDestructed - true if something else is responsible
421  ///   for calling destructors on this object
422  /// \param needsGC - true if the slot is potentially located
423  ///   somewhere that ObjC GC calls should be emitted for
424  static AggValueSlot forAddr(llvm::Value *addr, CharUnits align,
425                              Qualifiers quals,
426                              IsDestructed_t isDestructed,
427                              NeedsGCBarriers_t needsGC,
428                              IsAliased_t isAliased,
429                              IsZeroed_t isZeroed = IsNotZeroed) {
430    AggValueSlot AV;
431    AV.Addr = addr;
432    AV.Alignment = align.getQuantity();
433    AV.Quals = quals;
434    AV.DestructedFlag = isDestructed;
435    AV.ObjCGCFlag = needsGC;
436    AV.ZeroedFlag = isZeroed;
437    AV.AliasedFlag = isAliased;
438    return AV;
439  }
440
441  static AggValueSlot forLValue(const LValue &LV,
442                                IsDestructed_t isDestructed,
443                                NeedsGCBarriers_t needsGC,
444                                IsAliased_t isAliased,
445                                IsZeroed_t isZeroed = IsNotZeroed) {
446    return forAddr(LV.getAddress(), LV.getAlignment(),
447                   LV.getQuals(), isDestructed, needsGC, isAliased, isZeroed);
448  }
449
450  IsDestructed_t isExternallyDestructed() const {
451    return IsDestructed_t(DestructedFlag);
452  }
453  void setExternallyDestructed(bool destructed = true) {
454    DestructedFlag = destructed;
455  }
456
457  Qualifiers getQualifiers() const { return Quals; }
458
459  bool isVolatile() const {
460    return Quals.hasVolatile();
461  }
462
463  void setVolatile(bool flag) {
464    Quals.setVolatile(flag);
465  }
466
467  Qualifiers::ObjCLifetime getObjCLifetime() const {
468    return Quals.getObjCLifetime();
469  }
470
471  NeedsGCBarriers_t requiresGCollection() const {
472    return NeedsGCBarriers_t(ObjCGCFlag);
473  }
474
475  llvm::Value *getAddr() const {
476    return Addr;
477  }
478
479  bool isIgnored() const {
480    return Addr == nullptr;
481  }
482
483  CharUnits getAlignment() const {
484    return CharUnits::fromQuantity(Alignment);
485  }
486
487  IsAliased_t isPotentiallyAliased() const {
488    return IsAliased_t(AliasedFlag);
489  }
490
491  // FIXME: Alignment?
492  RValue asRValue() const {
493    return RValue::getAggregate(getAddr(), isVolatile());
494  }
495
496  void setZeroed(bool V = true) { ZeroedFlag = V; }
497  IsZeroed_t isZeroed() const {
498    return IsZeroed_t(ZeroedFlag);
499  }
500};
501
502}  // end namespace CodeGen
503}  // end namespace clang
504
505#endif
506