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[patch] passes.c: Don't call cleanup_cfg fromrest_of_handle_loop_optimize.


Hi,

Attached is a patch to remove a call to cleanup_cfg at the beginning
of rest_of_handle_loop_optimize.

Both rest_of_handle_cse and rest_of_handle_gcse call cleanup_cfg if
they change CFG.  Also, rest_of_handle_jump2 unconditoinally calls
cleanup_cfg, so rest_of_handle_loop does not need to call cleanup_cfg
at its beginning.  Since cleanup_cfg is a fixed point operation,
calling it twice in a row doesn't do any good.  Since
delete_dead_jumptables is part of cleanup_cfg, it doesn't make sense
to call it right after calling cleanup_cfg.

The patch removes the two calls delete_dead_jumptables and cleanup_cfg
at the beginning of rest_of_handle_loop_optimize.

Here is a timing in second for five runs of ./cc1 -quiet -O2 -o
/dev/null.

             original patched   diff%
c-common.i     17.955  17.940 -0.083%
combine.i      17.049  17.027 -0.129%
fold-const.i   37.434  37.398 -0.096%
insn-attrtab.i 46.702  46.281 -0.901%
reload1.i      13.321  13.267 -0.405%
reload.i       12.231  12.213 -0.147%
cc1-i files   216.464 216.327 -0.063%

I also confirmed that this patch makes no difference in the generated
code for cc1-i files, Linux kernel, generate-3.4.ii, tramp3d-v3.ii,
MICO, and POOMA.

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

Kazu Hirata

2005-02-14  Kazu Hirata  <kazu@cs.umass.edu>

	* passes.c (rest_of_handle_loop_optimize): Remove calls to
	delete_dead_jumptables and cleanup_cfg.

Index: passes.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/passes.c,v
retrieving revision 2.67
diff -u -d -p -r2.67 passes.c
--- passes.c	13 Feb 2005 03:58:21 -0000	2.67
+++ passes.c	14 Feb 2005 14:35:22 -0000
@@ -1075,8 +1075,6 @@ rest_of_handle_loop_optimize (void)
   int do_prefetch;
 
   timevar_push (TV_LOOP);
-  delete_dead_jumptables ();
-  cleanup_cfg (CLEANUP_EXPENSIVE | CLEANUP_PRE_LOOP);
   open_dump_file (DFI_loop, current_function_decl);
 
   /* CFG is no longer maintained up-to-date.  */


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