path: root/lib/CodeGen/CGValue.h

//===-- CGValue.h - LLVM CodeGen wrappers for llvm::Value* ------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// These classes implement wrappers around llvm::Value in order to
// fully represent the range of values for C L- and R- values.
//
//===----------------------------------------------------------------------===//

#ifndef CLANG_CODEGEN_CGVALUE_H
#define CLANG_CODEGEN_CGVALUE_H

#include "clang/AST/ASTContext.h"
#include "clang/AST/CharUnits.h"
#include "clang/AST/Type.h"
#include "llvm/IR/Value.h"

namespace llvm {
  class Constant;
  class MDNode;
}

namespace clang {
namespace CodeGen {
  class AggValueSlot;
  struct CGBitFieldInfo;

/// RValue - This trivial value class is used to represent the result of an
/// expression that is evaluated.  It can be one of three things: either a
/// simple LLVM SSA value, a pair of SSA values for complex numbers, or the
/// address of an aggregate value in memory.
class RValue {
  enum Flavor { Scalar, Complex, Aggregate };

  // Stores first value and flavor.
  llvm::PointerIntPair<llvm::Value *, 2, Flavor> V1;
  // Stores second value and volatility.
  llvm::PointerIntPair<llvm::Value *, 1, bool> V2;

public:
  bool isScalar() const { return V1.getInt() == Scalar; }
  bool isComplex() const { return V1.getInt() == Complex; }
  bool isAggregate() const { return V1.getInt() == Aggregate; }

  bool isVolatileQualified() const { return V2.getInt(); }

  /// getScalarVal() - Return the Value* of this scalar value.
  llvm::Value *getScalarVal() const {
    assert(isScalar() && "Not a scalar!");
    return V1.getPointer();
  }

  /// getComplexVal - Return the real/imag components of this complex value.
  ///
  std::pair<llvm::Value *, llvm::Value *> getComplexVal() const {
    return std::make_pair(V1.getPointer(), V2.getPointer());
  }

  /// getAggregateAddr() - Return the Value* of the address of the aggregate.
  llvm::Value *getAggregateAddr() const {
    assert(isAggregate() && "Not an aggregate!");
    return V1.getPointer();
  }

  static RValue get(llvm::Value *V) {
    RValue ER;
    ER.V1.setPointer(V);
    ER.V1.setInt(Scalar);
    ER.V2.setInt(false);
    return ER;
  }
  static RValue getComplex(llvm::Value *V1, llvm::Value *V2) {
    RValue ER;
    ER.V1.setPointer(V1);
    ER.V2.setPointer(V2);
    ER.V1.setInt(Complex);
    ER.V2.setInt(false);
    return ER;
  }
  static RValue getComplex(const std::pair<llvm::Value *, llvm::Value *> &C) {
    return getComplex(C.first, C.second);
  }
  // FIXME: Aggregate rvalues need to retain information about whether they are
  // volatile or not.  Remove default to find all places that probably get this
  // wrong.
  static RValue getAggregate(llvm::Value *V, bool Volatile = false) {
    RValue ER;
    ER.V1.setPointer(V);
    ER.V1.setInt(Aggregate);
    ER.V2.setInt(Volatile);
    return ER;
  }
};

/// Does an ARC strong l-value have precise lifetime?
enum ARCPreciseLifetime_t {
  ARCImpreciseLifetime, ARCPreciseLifetime
};

/// LValue - This represents an lvalue references.  Because C/C++ allow
/// bitfields, this is not a simple LLVM pointer, it may be a pointer plus a
/// bitrange.
class LValue {
  enum {
    Simple,       // This is a normal l-value, use getAddress().
    VectorElt,    // This is a vector element l-value (V[i]), use getVector*
    BitField,     // This is a bitfield l-value, use getBitfield*.
    ExtVectorElt  // This is an extended vector subset, use getExtVectorComp
  } LVType;

  llvm::Value *V;

  union {
    // Index into a vector subscript: V[i]
    llvm::Value *VectorIdx;

    // ExtVector element subset: V.xyx
    llvm::Constant *VectorElts;

    // BitField start bit and size
    const CGBitFieldInfo *BitFieldInfo;
  };

  QualType Type;

  // 'const' is unused here
  Qualifiers Quals;

  // The alignment to use when accessing this lvalue.  (For vector elements,
  // this is the alignment of the whole vector.)
  int64_t Alignment;

  // objective-c's ivar
  bool Ivar:1;
  
  // objective-c's ivar is an array
  bool ObjIsArray:1;

  // LValue is non-gc'able for any reason, including being a parameter or local
  // variable.
  bool NonGC: 1;

  // Lvalue is a global reference of an objective-c object
  bool GlobalObjCRef : 1;
  
  // Lvalue is a thread local reference
  bool ThreadLocalRef : 1;

  // Lvalue has ARC imprecise lifetime.  We store this inverted to try
  // to make the default bitfield pattern all-zeroes.
  bool ImpreciseLifetime : 1;

  Expr *BaseIvarExp;

  /// Used by struct-path-aware TBAA.
  QualType TBAABaseType;
  /// Offset relative to the base type.
  uint64_t TBAAOffset;

  /// TBAAInfo - TBAA information to attach to dereferences of this LValue.
  llvm::MDNode *TBAAInfo;

private:
  void Initialize(QualType Type, Qualifiers Quals,
                  CharUnits Alignment,
                  llvm::MDNode *TBAAInfo = 0) {
    this->Type = Type;
    this->Quals = Quals;
    this->Alignment = Alignment.getQuantity();
    assert(this->Alignment == Alignment.getQuantity() &&
           "Alignment exceeds allowed max!");

    // Initialize Objective-C flags.
    this->Ivar = this->ObjIsArray = this->NonGC = this->GlobalObjCRef = false;
    this->ImpreciseLifetime = false;
    this->ThreadLocalRef = false;
    this->BaseIvarExp = 0;

    // Initialize fields for TBAA.
    this->TBAABaseType = Type;
    this->TBAAOffset = 0;
    this->TBAAInfo = TBAAInfo;
  }

public:
  bool isSimple() const { return LVType == Simple; }
  bool isVectorElt() const { return LVType == VectorElt; }
  bool isBitField() const { return LVType == BitField; }
  bool isExtVectorElt() const { return LVType == ExtVectorElt; }

  bool isVolatileQualified() const { return Quals.hasVolatile(); }
  bool isRestrictQualified() const { return Quals.hasRestrict(); }
  unsigned getVRQualifiers() const {
    return Quals.getCVRQualifiers() & ~Qualifiers::Const;
  }

  QualType getType() const { return Type; }

  Qualifiers::ObjCLifetime getObjCLifetime() const {
    return Quals.getObjCLifetime();
  }

  bool isObjCIvar() const { return Ivar; }
  void setObjCIvar(bool Value) { Ivar = Value; }

  bool isObjCArray() const { return ObjIsArray; }
  void setObjCArray(bool Value) { ObjIsArray = Value; }

  bool isNonGC () const { return NonGC; }
  void setNonGC(bool Value) { NonGC = Value; }

  bool isGlobalObjCRef() const { return GlobalObjCRef; }
  void setGlobalObjCRef(bool Value) { GlobalObjCRef = Value; }

  bool isThreadLocalRef() const { return ThreadLocalRef; }
  void setThreadLocalRef(bool Value) { ThreadLocalRef = Value;}

  ARCPreciseLifetime_t isARCPreciseLifetime() const {
    return ARCPreciseLifetime_t(!ImpreciseLifetime);
  }
  void setARCPreciseLifetime(ARCPreciseLifetime_t value) {
    ImpreciseLifetime = (value == ARCImpreciseLifetime);
  }

  bool isObjCWeak() const {
    return Quals.getObjCGCAttr() == Qualifiers::Weak;
  }
  bool isObjCStrong() const {
    return Quals.getObjCGCAttr() == Qualifiers::Strong;
  }

  bool isVolatile() const {
    return Quals