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[oota-llvm.git] / include / llvm / GlobalValue.h

diff --git a/include/llvm/GlobalValue.h b/include/llvm/GlobalValue.h
index 942d9b9a4081ded2b6e951a24dfbea4943ba8d43..ca189b2cbe166d5a5d3f1bf497ee9d089fdc7a53 100644 (file)
--- a/include/llvm/GlobalValue.h
+++ b/include/llvm/GlobalValue.h
@@ -1,10 +1,10 @@
 //===-- llvm/GlobalValue.h - Class to represent a global value --*- 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 is a common base class of all globally definable objects.  As such,
@@ -17,32 +17,55 @@
 #ifndef LLVM_GLOBALVALUE_H
 #define LLVM_GLOBALVALUE_H
 
-#include "llvm/User.h"
+#include "llvm/Constant.h"
 
 namespace llvm {
 
 class PointerType;
 class Module;
 
-class GlobalValue : public User {
+class GlobalValue : public Constant {
   GlobalValue(const GlobalValue &);             // do not implement
 public:
   enum LinkageTypes {
-    ExternalLinkage,   // Externally visible function
-    LinkOnceLinkage,   // Keep one copy of named function when linking (inline)
-    WeakLinkage,       // Keep one copy of named function when linking (weak)
-    AppendingLinkage,  // Special purpose, only applies to global arrays
-    InternalLinkage    // Rename collisions when linking (static functions)
+    ExternalLinkage,   /// Externally visible function
+    LinkOnceLinkage,   /// Keep one copy of named function when linking (inline)
+    WeakLinkage,       /// Keep one copy of named function when linking (weak)
+    AppendingLinkage,  /// Special purpose, only applies to global arrays
+    InternalLinkage,   /// Rename collisions when linking (static functions)
+    GhostLinkage       /// Stand-in functions for streaming fns from BC files
   };
 protected:
-  GlobalValue(const Type *Ty, ValueTy vty, LinkageTypes linkage,
-             const std::string &name = "")
-    : User(Ty, vty, name), Linkage(linkage), Parent(0) {}
+  GlobalValue(const Type *Ty, ValueTy vty, Use *Ops, unsigned NumOps,
+              LinkageTypes linkage, const std::string &name = "")
+    : Constant(Ty, vty, Ops, NumOps, name), 
+      Parent(0), Linkage(linkage), Alignment(0) { }
 
-  LinkageTypes Linkage;   // The linkage of this global
   Module *Parent;
+  LinkageTypes Linkage;   // The linkage of this global
+  unsigned Alignment;     // Alignment of this symbol, must be power of two
+  std::string Section;    // Section to emit this into, empty mean default
 public:
-  ~GlobalValue() {}
+  ~GlobalValue() {
+    removeDeadConstantUsers();   // remove any dead constants using this.
+  }
+
+  unsigned getAlignment() const { return Alignment; }
+  void setAlignment(unsigned Align) {
+    assert((Align & (Align-1)) == 0 && "Alignment is not a power of 2!");
+    Alignment = Align;
+  }
+  
+  bool hasSection() const { return !Section.empty(); }
+  const std::string &getSection() const { return Section; }
+  void setSection(const std::string &S) { Section = S; }
+  
+  /// If the usage is empty (except transitively dead constants), then this
+  /// global value can can be safely deleted since the destructor will
+  /// delete the dead constants as well.
+  /// @brief Determine if the usage of this global value is empty except
+  /// for transitively dead constants.
+  bool use_empty_except_constants();
 
   /// getType - Global values are always pointers.
   inline const PointerType *getType() const {
@@ -57,6 +80,20 @@ public:
   void setLinkage(LinkageTypes LT) { Linkage = LT; }
   LinkageTypes getLinkage() const { return Linkage; }
 
+  /// hasNotBeenReadFromBytecode - If a module provider is being used to lazily
+  /// stream in functions from disk, this method can be used to check to see if
+  /// the function has been read in yet or not.  Unless you are working on the
+  /// JIT or something else that streams stuff in lazily, you don't need to
+  /// worry about this.
+  bool hasNotBeenReadFromBytecode() const { return Linkage == GhostLinkage; }
+
+  /// Override from Constant class. No GlobalValue's are null values so this
+  /// always returns false.
+  virtual bool isNullValue() const { return false; }
+
+  /// Override from Constant class.
+  virtual void destroyConstant();
+
   /// isExternal - Return true if the primary definition of this global value is
   /// outside of the current translation unit...
   virtual bool isExternal() const = 0;
@@ -66,10 +103,20 @@ public:
   inline Module *getParent() { return Parent; }
   inline const Module *getParent() const { return Parent; }
 
+  /// removeDeadConstantUsers - If there are any dead constant users dangling
+  /// off of this global value, remove them.  This method is useful for clients
+  /// that want to check to see if a global is unused, but don't want to deal
+  /// with potentially dead constants hanging off of the globals.
+  ///
+  /// This method tries to make the global dead.  If it detects a user that
+  /// would prevent it from becoming completely dead, it gives up early,
+  /// potentially leaving some dead constant users around.
+  void removeDeadConstantUsers();
+
   // Methods for support type inquiry through isa, cast, and dyn_cast:
-  static inline bool classof(const GlobalValue *T) { return true; }
+  static inline bool classof(const GlobalValue *) { return true; }
   static inline bool classof(const Value *V) {
-    return V->getValueType() == Value::FunctionVal || 
+    return V->getValueType() == Value::FunctionVal ||
            V->getValueType() == Value::GlobalVariableVal;
   }
 };