Zdenek Kotala wrote:
>
> Main problem is -fast switch. It modifies behavior of floating point
> operation (it is reason why It is not good option for postgres) and
> use another floating point libraries and some function are inlined. It
> is reason why pow test passed with -fast switch without -lm switch.
>
> Detail description of -fast you can found on
> http://docs.sun.com/source/819-3688/cc_ops.app.html
>
I noticed that the Sun FAQ now has changed from hinting that -fast might
be very beneficial to recomend staying away from it.
Using -fast is an old habit, has been building with it for years. I've
seen that the testsuite breaks (in date/time) with only -fast, but it
seems the only option one has to disable to normalize floating point
enough is -fns. I hope passing the testsuite really means that fp math
behaves correctly. If I'm wrong about that, I'll have to change our
build routine.
Beeing lazy, it is a good bit easier to go with -fast and turn of the
problematic optimization with:
-fast -fns=no
than expanding the -fast macro and having to add all parameters:
-dalign -nofstore -fsimple=2 -fsingle -xalias_level=basic -native
-xdepend -xlibmil -xlibmopt -xO5 -xregs=frameptr
I do understand the recomendation to avoid -fast, the tweaking is both
compiler version and hardware architecture dependant. Doing a make check
is always advisable.
regards,
Andreas
