[Valgrind-users] Preliminary little speedup patch (seen 7% speedup)

[Christian L. <chr...@le...>]

Hello,

first let me say:

valgrind is absolutly great, thank you for it!
It saved me allready often.

Because I was not able to add MMX support (seems not to be exactly
easy).
I saw this realy big switch(opt){case 0x00....} statement and thought
"this must be slow".

So I tried the "Labels as Values" feature of the gcc.
(http://www.dis.com/gnu/gcc/gcc_79.html#SEC79)
Yes it is a gcc feature, but because is specially for x86/Linux I can't
see a problem.

"benchmark":
core:/home/ijuz/Mail/la# ls -l
total 4508
-rw-------    1 ijuz     ijuz      4602189 Mar 17 11:56
politech_at_politechbot_com

core:/home/ijuz/Mail/la# nice -n -10 time /work/dev/val/bin/valgrind
gzip -9 politech_at_politechbot_com

normali-cvs:
13.57user 0.09system 0:14.07elapsed 97%CPU (0avgtext+0avgdata
0maxresident)k
13.51user 0.08system 0:14.01elapsed 96%CPU (0avgtext+0avgdata
0maxresident)k

patched-cvs:
12.54user 0.06system 0:13.07elapsed 96%CPU (0avgtext+0avgdata
0maxresident)k
12.56user 0.06system 0:12.97elapsed 97%CPU (0avgtext+0avgdata
0maxresident)k

this means (average):

13.54 -> 12.55
that is a speedup of about 7% in this case

If you (Julian or Nick) are perhaps interested in it, I would clean it up
further and remove this one switch() { } statement.

I appended the patch, I hope nobody objects because of this few kb.
(It is against the cvs from now)

Regards,
Christian Leber

-- 
  "Omnis enim res, quae dando non deficit, dum habetur et non datur,
   nondum habetur, quomodo habenda est."       (Aurelius Augustinus)
  Translation: <http://gnuhh.org/work/fsf-europe/augustinus.html>