This checkin basically amounts to a complete rewrite of the type-resolution

machinery.  This dramatically simplifies how things works, removes irritating
little corner cases, and overall improves speed and reliability.

Highlights of this change are:

1. The exponential algorithm built into the code is now gone.  For example
   the time to disassemble one bytecode file from the mesa benchmark went
   from taking 12.5s to taking 0.16s.
2. The linker bugs should be dramatically reduced.  The one remaining bug
   has to do with constant handling, which I actually introduced in
   "union-find" checkins.
3. The code is much easier to follow, as a result of fewer special cases.
   It's probably also smaller.  yaay.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@8842 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 12 insertions, 16 deletions

diff --git a/include/llvm/AbstractTypeUser.h b/include/llvm/AbstractTypeUser.h
index b9e5f1c659..e4096787f4 100644
--- a/include/llvm/AbstractTypeUser.h
+++ b/include/llvm/AbstractTypeUser.h
@@ -38,24 +38,20 @@ protected:
   virtual ~AbstractTypeUser() {}                        // Derive from me
 public:
 
-  // refineAbstractType - The callback method invoked when an abstract type
-  // has been found to be more concrete.  A class must override this method to
-  // update its internal state to reference NewType instead of OldType.  Soon
-  // after this method is invoked, OldType shall be deleted, so referencing it
-  // is quite unwise.
-  //
-  // Another case that is important to consider is when a type is refined, but
-  // stays in the same place in memory.  In this case OldTy will equal NewTy.
-  // This callback just notifies ATU's that the underlying structure of the type
-  // has changed... but any previously used properties are still valid.
-  //
-  // Note that it is possible to refine a type with parameters OldTy==NewTy, and
-  // OldTy is no longer abstract.  In this case, abstract type users should
-  // release their hold on a type, because it went from being abstract to
-  // concrete.
-  //
+  /// refineAbstractType - The callback method invoked when an abstract type is
+  /// resolved to another type.  An object must override this method to update
+  /// its internal state to reference NewType instead of OldType.
+  ///
   virtual void refineAbstractType(const DerivedType *OldTy,
 				  const Type *NewTy) = 0;
+
+  /// The other case which AbstractTypeUsers must be aware of is when a type
+  /// makes the transition from being abstract (where it has clients on it's
+  /// AbstractTypeUsers list) to concrete (where it does not).  This method
+  /// notifies ATU's when this occurs for a type.
+  ///
+  virtual void typeBecameConcrete(const DerivedType *AbsTy) = 0;
+
   // for debugging...
   virtual void dump() const = 0;
 };