Dead Vtbody Elimination

Similar to dead code elimination in optimizing compilers. Dead Vtbody Elimination removes a vtbody that is not called by other vtbodies. An automated version of the transformation is also available that removes all vtbodies not called by others. For example, applying Dead Vtbody Elimination to the VT on the right side of Figure 3-2 would remove vtbody V2 B, which is no longer referenced by other vtbodies. This transformation is typically applied after Vtbody Inline Expansion. 

First, unnecessary microsubroutine calls can be eliminated by using Vtbody Inline Expansion to recursively expand all vtbodies inline, producing a single large vtbody if possible. Once this expansion has been performed. Dead Vtbody Elimination can be used to remove the vtbodies that are no longer referenced. 

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