[Bug rtl-optimization/19780] Floating point computation far slower for -mfpmath=sse

[amacleod at redhat dot com]

------- Comment #19 from amacleod at redhat dot com  2007-04-05 17:24 -------
what are you using for a compiler? Im using a mainline from mid march, and with
it, my .optimized files diff exactly the same, and I get the aforementioned
time differences in the executables.
(sse.c and sse-bad.c are same, just different names to get different output
files)

2007-03-13/gcc> diff sse.c sse-bad.c

2007-03-13/gcc>./xgcc -B./ sse.c -fdump-tree-optimized -O3 -march=pentium4 -o
sse

2007-03-13/gcc>./xgcc -B./ sse-bad.c -fdump-tree-optimized -O3 -march=pentium4
-mfpmath=sse -o sse-bad

2007-03-13/gcc>ls -l sse*optimized

-rw-rw-r--  1 amacleod amacleod 864 Apr  5 12:16 sse-bad.c.116t.optimized
-rw-rw-r--  1 amacleod amacleod 864 Apr  5 12:16 sse.c.116t.optimized

2007-03-13/gcc>diff sse.c.116t.optimized sse-bad.c.116t.optimized

2007-03-13/gcc>time ./sse

Start?
Stop!
Result = 0.000000, 0.000000, 1.000000

real    0m0.630s
user    0m0.572s
sys     0m0.000s

2007-03-13/gcc>time ./sse-bad

Start?
Stop!
Result = 0.000000, 0.000000, 1.000000

real    0m0.883s
user    0m0.780s
sys     0m0.000s


Is this just with earlier compilers, what version are you using?  It at least
seems to indicate that the problem isn't before out-of-ssa since the time issue
is still there with identical outputs from .optimized


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19780