[patch] cfghooks.c: Speed up delete_basic_block.

[Kazu Hirata]

Hi,

Attached is a patch to speed up delete_basic_block by removing
meaningless code, namely, code to truncate edge vectors.

Right above these two calls to VEC_truncate, we have code to remove
all incoming and outgoing edges, so we don't need to truncate the edge
vectors.

Tested on i686-pc-linux-gnu.  OK to apply?

Kazu Hirata

2004-11-04  Kazu Hirata  <kazu@cs.umass.edu>

	* cfghooks.c (delete_basic_block): Remove code to truncate
	edge vectors.

Index: cfghooks.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/cfghooks.c,v
retrieving revision 1.17
diff -U5 -d -p -r1.17 cfghooks.c
--- cfghooks.c	16 Oct 2004 16:58:58 -0000	1.17
+++ cfghooks.c	3 Nov 2004 03:41:39 -0000
@@ -366,13 +366,10 @@ delete_basic_block (basic_block bb)
   while (EDGE_COUNT (bb->preds) != 0)
     remove_edge (EDGE_PRED (bb, 0));
   while (EDGE_COUNT (bb->succs) != 0)
     remove_edge (EDGE_SUCC (bb, 0));
 
-  VEC_truncate (edge, bb->preds, 0);
-  VEC_truncate (edge, bb->succs, 0);
-
   if (dom_computed[CDI_DOMINATORS])
     delete_from_dominance_info (CDI_DOMINATORS, bb);
   if (dom_computed[CDI_POST_DOMINATORS])
     delete_from_dominance_info (CDI_POST_DOMINATORS, bb);