Import LLVM, at r72732.

1 files changed, 142 insertions, 0 deletions

diff --git a/include/llvm/Constant.h b/include/llvm/Constant.h
new file mode 100644
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--- /dev/null
+++ b/include/llvm/Constant.h
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+//===-- llvm/Constant.h - Constant class definition -------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains the declaration of the Constant class.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CONSTANT_H
+#define LLVM_CONSTANT_H
+
+#include "llvm/User.h"
+
+namespace llvm {
+  template<typename T> class SmallVectorImpl;
+
+  /// If object contains references to other objects, then relocations are
+  /// usually required for emission of such object (especially in PIC mode). One
+  /// usually distinguishes local and global relocations. Local relocations are
+  /// made wrt objects in the same module and these objects have local (internal
+  /// or private) linkage. Global relocations are made wrt externally visible
+  /// objects. In most cases local relocations can be resolved via so-called
+  /// 'pre-link' technique.
+  namespace Reloc {
+    const unsigned None   = 0;
+    const unsigned Local  = 1 << 0; ///< Local relocations are required
+    const unsigned Global = 1 << 1; ///< Global relocations are required
+    const unsigned LocalOrGlobal = Local | Global;
+  }
+
+/// This is an important base class in LLVM. It provides the common facilities
+/// of all constant values in an LLVM program. A constant is a value that is
+/// immutable at runtime. Functions are constants because their address is
+/// immutable. Same with global variables. 
+/// 
+/// All constants share the capabilities provided in this class. All constants
+/// can have a null value. They can have an operand list. Constants can be
+/// simple (integer and floating point values), complex (arrays and structures),
+/// or expression based (computations yielding a constant value composed of 
+/// only certain operators and other constant values).
+/// 
+/// Note that Constants are immutable (once created they never change) 
+/// and are fully shared by structural equivalence.  This means that two 
+/// structurally equivalent constants will always have the same address.  
+/// Constants are created on demand as needed and never deleted: thus clients 
+/// don't have to worry about the lifetime of the objects.
+/// @brief LLVM Constant Representation
+class Constant : public User {
+  void operator=(const Constant &);     // Do not implement
+  Constant(const Constant &);           // Do not implement
+protected:
+  Constant(const Type *ty, ValueTy vty, Use *Ops, unsigned NumOps)
+    : User(ty, vty, Ops, NumOps) {}
+
+  void destroyConstantImpl();
+public:
+  /// Static constructor to get a '0' constant of arbitrary type...
+  ///
+  static Constant *getNullValue(const Type *Ty);
+
+  /// Static constructor to get a '-1' constant.  This supports integers and
+  /// vectors.
+  ///
+  static Constant *getAllOnesValue(const Type *Ty);
+  
+  /// isNullValue - Return true if this is the value that would be returned by
+  /// getNullValue.
+  virtual bool isNullValue() const = 0;
+
+  /// canTrap - Return true if evaluation of this constant could trap.  This is
+  /// true for things like constant expressions that could divide by zero.
+  bool canTrap() const;
+
+  /// ContainsRelocations - Return true if the constant value contains
+  /// relocations which cannot be resolved at compile time. Note that answer is
+  /// not exclusive: there can be possibility that relocations of other kind are
+  /// required as well.
+  bool ContainsRelocations(unsigned Kind = Reloc::LocalOrGlobal) const;
+
+  // Specialize get/setOperand for Constants as their operands are always
+  // constants as well.
+  Constant *getOperand(unsigned i) {
+    return static_cast<Constant*>(User::getOperand(i));
+  }
+  const Constant *getOperand(unsigned i) const {
+    return static_cast<const Constant*>(User::getOperand(i));
+  }
+  void setOperand(unsigned i, Constant *C) {
+    User::setOperand(i, C);
+  }
+  
+  /// getVectorElements - This method, which is only valid on constant of vector
+  /// type, returns the elements of the vector in the specified smallvector.
+  /// This handles breaking down a vector undef into undef elements, etc.  For
+  /// constant exprs and other cases we can't handle, we return an empty vector.
+  void getVectorElements(SmallVectorImpl<Constant*> &Elts) const;
+
+  /// destroyConstant - Called if some element of this constant is no longer
+  /// valid.  At this point only other constants may be on the use_list for this
+  /// constant.  Any constants on our Use list must also be destroy'd.  The
+  /// implementation must be sure to remove the constant from the list of
+  /// available cached constants.  Implementations should call
+  /// destroyConstantImpl as the last thing they do, to destroy all users and
+  /// delete this.
+  virtual void destroyConstant() { assert(0 && "Not reached!"); }
+
+  //// Methods for support type inquiry through isa, cast, and dyn_cast:
+  static inline bool classof(const Constant *) { return true; }
+  static inline bool classof(const GlobalValue *) { return true; }
+  static inline bool classof(const Value *V) {
+    return V->getValueID() >= ConstantFirstVal &&
+           V->getValueID() <= ConstantLastVal;
+  }
+
+  /// replaceUsesOfWithOnConstant - This method is a special form of
+  /// User::replaceUsesOfWith (which does not work on constants) that does work
+  /// on constants.  Basically this method goes through the trouble of building
+  /// a new constant that is equivalent to the current one, with all uses of
+  /// From replaced with uses of To.  After this construction is completed, all
+  /// of the users of 'this' are replaced to use the new constant, and then
+  /// 'this' is deleted.  In general, you should not call this method, instead,
+  /// use Value::replaceAllUsesWith, which automatically dispatches to this
+  /// method as needed.
+  ///
+  virtual void replaceUsesOfWithOnConstant(Value *, Value *, Use *) {
+    // Provide a default implementation for constants (like integers) that
+    // cannot use any other values.  This cannot be called at runtime, but needs
+    // to be here to avoid link errors.
+    assert(getNumOperands() == 0 && "replaceUsesOfWithOnConstant must be "
+           "implemented for all constants that have operands!");
+    assert(0 && "Constants that do not have operands cannot be using 'From'!");
+  }
+};
+
+} // End llvm namespace
+
+#endif