[patch] Improve basic block merging

Diego Novillo dnovillo@redhat.com
Sun Nov 12 16:53:00 GMT 2006

Zdenek Dvorak wrote on 11/11/06 17:27:

> This behavior is overly conservative.  If only symbols are marked for
> renaming (not ssa names), then eliminating the phi nodes is still
> safe (as the phi nodes for the affected symbols are ignored during
> ssa update, anyway).
Well, not "ignored".  They are used if present, and inserted if needed. 
  But your observation is valid.

> 	* tree-flow.h (non_symbol_need_ssa_update_p): Declare.
> 	* tree-into-ssa.c (non_symbol_need_ssa_update_p): New function.
> 	* tree-cfg.c (tree_can_merge_blocks_p): Check
> 	non_symbol_need_ssa_update_p instead of need_ssa_update_p.

> + /* Return true if any non-symbol is registered for ssa updating.  */
> + 
/* Return true if SSA name mappings have been registered for SSA 
updating.  */

OK with those changes.

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