X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=include%2Fllvm%2FGlobalVariable.h;h=597583b2ceed10dc0f2f1af8efd7e58e85869db4;hb=0f899c78e18e39a8ccd08386aaa493a1b9a712a3;hp=28eaa624e9d2b2e710cce9d0f0568748712b5696;hpb=e9b11b431308f4766b73cda93e38ec930c912122;p=oota-llvm.git

diff --git a/include/llvm/GlobalVariable.h b/include/llvm/GlobalVariable.h
index 28eaa624e9d..597583b2cee 100644
--- a/include/llvm/GlobalVariable.h
+++ b/include/llvm/GlobalVariable.h
@@ -23,12 +23,12 @@
 #include "llvm/GlobalValue.h"
 #include "llvm/OperandTraits.h"
 #include "llvm/ADT/ilist_node.h"
+#include "llvm/ADT/Twine.h"
 
 namespace llvm {
 
 class Module;
 class Constant;
-class LLVMContext;
 template<typename ValueSubClass, typename ItemParentClass>
   class SymbolTableListTraits;
 
@@ -50,15 +50,14 @@ public:
   }
   /// GlobalVariable ctor - If a parent module is specified, the global is
   /// automatically inserted into the end of the specified modules global list.
-  GlobalVariable(LLVMContext &Context, const Type *Ty, bool isConstant,
-                 LinkageTypes Linkage,
-                 Constant *Initializer = 0, const std::string &Name = "",
+  GlobalVariable(const Type *Ty, bool isConstant, LinkageTypes Linkage,
+                 Constant *Initializer = 0, const Twine &Name = "",
                  bool ThreadLocal = false, unsigned AddressSpace = 0);
   /// GlobalVariable ctor - This creates a global and inserts it before the
   /// specified other global.
   GlobalVariable(Module &M, const Type *Ty, bool isConstant,
                  LinkageTypes Linkage, Constant *Initializer,
-                 const std::string &Name,
+                 const Twine &Name,
                  GlobalVariable *InsertBefore = 0, bool ThreadLocal = false,
                  unsigned AddressSpace = 0);
 
@@ -69,7 +68,7 @@ public:
   /// Provide fast operand accessors
   DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
 
-  /// isDeclaration - Is this global variable lacking an initializer?  If so, 
+  /// isDeclaration - Is this global variable lacking an initializer?  If so,
   /// the global variable is defined in some other translation unit, and is thus
   /// only a declaration here.
   virtual bool isDeclaration() const { return getNumOperands() == 0; }
@@ -81,7 +80,21 @@ public:
   inline bool hasInitializer() const { return !isDeclaration(); }
 
   /// hasDefinitiveInitializer - Whether the global variable has an initializer,
-  /// and this is the initializer that will be used in the final executable.
+  /// and any other instances of the global (this can happen due to weak
+  /// linkage) are guaranteed to have the same initializer.
+  ///
+  /// Note that if you want to transform a global, you must use
+  /// hasUniqueInitializer() instead, because of the *_odr linkage type.
+  ///
+  /// Example:
+  ///
+  /// @a = global SomeType* null - Initializer is both definitive and unique.
+  ///
+  /// @b = global weak SomeType* null - Initializer is neither definitive nor
+  /// unique.
+  ///
+  /// @c = global weak_odr SomeType* null - Initializer is definitive, but not
+  /// unique.
   inline bool hasDefinitiveInitializer() const {
     return hasInitializer() &&
       // The initializer of a global variable with weak linkage may change at
@@ -89,6 +102,19 @@ public:
       !mayBeOverridden();
   }
 
+  /// hasUniqueInitializer - Whether the global variable has an initializer, and
+  /// any changes made to the initializer will turn up in the final executable.
+  inline bool hasUniqueInitializer() const {
+    return hasInitializer() &&
+      // It's not safe to modify initializers of global variables with weak
+      // linkage, because the linker might choose to discard the initializer and
+      // use the initializer from another instance of the global variable
+      // instead. It is wrong to modify the initializer of a global variable
+      // with *_odr linkage because then different instances of the global may
+      // have different initializers, breaking the One Definition Rule.
+      !isWeakForLinker();
+  }
+
   /// getInitializer - Return the initializer for this global variable.  It is
   /// illegal to call this method if the global is external, because we cannot
   /// tell what the value is initialized to!
@@ -101,18 +127,10 @@ public:
     assert(hasInitializer() && "GV doesn't have initializer!");
     return static_cast<Constant*>(Op<0>().get());
   }
-  inline void setInitializer(Constant *CPV) {
-    if (CPV == 0) {
-      if (hasInitializer()) {
-        Op<0>().set(0);
-        NumOperands = 0;
-      }
-    } else {
-      if (!hasInitializer())
-        NumOperands = 1;
-      Op<0>().set(CPV);
-    }
-  }
+  /// setInitializer - Sets the initializer for this global variable, removing
+  /// any existing initializer if InitVal==NULL.  If this GV has type T*, the
+  /// initializer must have type T.
+  void setInitializer(Constant *InitVal);
 
   /// If the value is a global constant, its value is immutable throughout the
   /// runtime execution of the program.  Assigning a value into the constant
@@ -151,7 +169,7 @@ public:
 };
 
 template <>
-struct OperandTraits<GlobalVariable> : OptionalOperandTraits<> {
+struct OperandTraits<GlobalVariable> : public OptionalOperandTraits<> {
 };
 
 DEFINE_TRANSPARENT_OPERAND_ACCESSORS(GlobalVariable, Value)