------- Additional Comments From uros at kss-loka dot si 2005-09-30 09:39
-------
(In reply to comment #8)
> time for no recip pass (comment #4): 1.43 * 100 / 10.05 = 14.22
The time above is with -ffast-math, with current recip pass disabled
> time for new recip pass (comment #6): 1.85 * 100 / 12.04 = 15.36
The time above is without -ffast-math, with current recip pass enabled
I have done some more measusrement, with gcc version 4.1.0 20050930 and your
patch commited. First results are with recip pass disabled ("&& 0" was added to
gate_cse_reciprocals()). Three runs were performed:
Without recip pass:
povray -display=NONE abyss.pov:
user 0m15.770s
user 0m15.824s
user 0m15.781s
=================
0m15.7917
Next results are with recip pass enabled:
povray_recip -display=NONE abyss.pov:
user 0m15.891s
user 0m15.826s
user 0m15.867s
=================
0m15.8613 (+ 0.44%)
The povray was compiled with:
CFLAGS = -pipe -O3 -msse -mfpmath=387 -ffast-math -D__NO_MATH_INLINES -msse2
-march=pentium4 -mtune=pentium4 -malign-double -minline-all-stringops
CXXFLAGS = -pipe -Wno-multichar -O3 -msse -mfpmath=387 -ffast-math
-D__NO_MATH_INLINES -msse2 -march=pentium4 -mtune=pentium4 -malign-double
-minline-all-stringops
In my case, recip pass marginally increases run times for -mfpmath=387.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24123
