X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=include%2Fllvm%2FConstant.h;h=bfe65a6faa1549278cccd3d71e94c8c04a7041a3;hb=2c783e46c3480c7fa8b91b10610a8e0d92e33ccd;hp=48f1fcce194bedcee9f8bfd9bebc6db4f3be1931;hpb=48486893f46d2e12e926682a3ecb908716bc66c4;p=oota-llvm.git

diff --git a/include/llvm/Constant.h b/include/llvm/Constant.h
index 48f1fcce194..bfe65a6faa1 100644
--- a/include/llvm/Constant.h
+++ b/include/llvm/Constant.h
@@ -1,5 +1,12 @@
 //===-- llvm/Constant.h - Constant class definition -------------*- C++ -*-===//
 //
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
 // This file contains the declaration of the Constant class.
 //
 //===----------------------------------------------------------------------===//
@@ -9,16 +16,34 @@
 
 #include "llvm/User.h"
 
+namespace llvm {
+
+/// 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.  
+/// Constant's 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:
-  inline Constant(const Type *Ty) : User(Ty, Value::ConstantVal) {}
-  ~Constant() {}
+  Constant(const Type *Ty, ValueTy vty, Use *Ops, unsigned NumOps)
+    : User(Ty, vty, Ops, NumOps) {}
 
   void destroyConstantImpl();
 public:
-  // setName - Specialize setName to handle symbol table majik...
-  virtual void setName(const std::string &name, SymbolTable *ST = 0);
-
   /// Static constructor to get a '0' constant of arbitrary type...
   ///
   static Constant *getNullValue(const Type *Ty);
@@ -28,11 +53,27 @@ public:
   virtual bool isNullValue() const = 0;
 
   virtual void print(std::ostream &O) const;
+  void print(std::ostream *O) const { if (O) print(*O); }
+  
+  /// 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;
 
-  /// isConstantExpr - Return true if this is a ConstantExpr
-  ///
-  virtual bool isConstantExpr() const { return false; }
+  /// ContaintsRelocations - Return true if the constant value contains
+  /// relocations which cannot be resolved at compile time.
+  bool ContainsRelocations() const;
 
+  // Specialize get/setOperand for Constant's 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);
+  }
 
   /// 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
@@ -41,20 +82,14 @@ public:
   /// available cached constants.  Implementations should call
   /// destroyConstantImpl as the last thing they do, to destroy all users and
   /// delete this.
-  ///
-  /// Note that this call is only valid on non-primitive constants: You cannot
-  /// destroy an integer constant for example.  This API is used to delete
-  /// constants that have ConstantPointerRef's embeded in them when the module
-  /// is deleted, and it is used by GlobalDCE to remove ConstantPointerRefs that
-  /// are unneeded, allowing globals to be DCE'd.
-  ///
   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->getValueType() == Value::ConstantVal;
+    return V->getValueID() >= ConstantFirstVal &&
+           V->getValueID() <= ConstantLastVal;
   }
 
   /// replaceUsesOfWithOnConstant - This method is a special form of
@@ -67,8 +102,7 @@ public:
   /// use Value::replaceAllUsesWith, which automatically dispatches to this
   /// method as needed.
   ///
-  virtual void replaceUsesOfWithOnConstant(Value *From, Value *To,
-                                           bool DisableChecking = false) {
+  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.
@@ -77,11 +111,14 @@ public:
     assert(0 && "Constants that do not have operands cannot be using 'From'!");
   }
 
-  // WARNING: Only to be used by Bytecode & Assembly Parsers!  USER CODE SHOULD
-  // NOT USE THIS!!
-  // Returns the number of uses of OldV that were replaced.
-  unsigned mutateReferences(Value* OldV, Value *NewV);
-  // END WARNING!!
+  /// getStringValue - Turn an LLVM constant pointer that eventually points to a
+  /// global into a string value.  Return an empty string if we can't do it.
+  /// Parameter Chop determines if the result is chopped at the first null
+  /// terminator.
+  ///
+  std::string getStringValue(bool Chop = true, unsigned Offset = 0);
 };
 
+} // End llvm namespace
+
 #endif