[csw-maintainers] new wiki page Enable Fast Install Information

Mike Watters mwatters at opencsw.org
Mon Mar 16 19:00:32 CET 2009


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Philip Brown wrote:
>> That is just because of the wrong link - if you are logged in
>> you get https-prefix which needs login, http does not.
> [...]
> 
> so, 
> 
> http://apps.sourceforge.net/mediawiki/gar/index.php?title=Fast_Install
> 
> i have some comments:
> "Do not use this option for programs that depend on IEEE standard exception
>  handling; you can get different numerical results, premature program
>  termination, or unexpected SIGFPE signals."

Unfortunately that is the recommendation from the manpage for Sun's cc
I have not looked at any specific C++ only programs to see if it is on or off by default.

it gets better, I just pulled up the man page for gcc the equivilant option is -ffast-math
and it says basically the same thing. I will add the gcc piece to the page as well.

[ ==> Begin Quote <== ]
 -ffast-math
         Sets -fno-math-errno, -funsafe-math-optimizations,
         -fno-trapping-math, -ffinite-math-only,
         -fno-rounding-math and -fno-signaling-nans.

         This option causes the preprocessor macro
         "__FAST_MATH__" to be defined.

         This option should never be turned on by any -O option
         since it can result in incorrect output for programs
         which depend on an exact implementation of IEEE or ISO
         rules/specifications for math functions.
[ ==> End Quote <== ]
it then goes on to explain each of the options set by the flag...

> 
> So basically, "never use -fast, with C++ programs"  :-/
> exception handling is really important with many C++ programs.
> Demons, certainly.
> 
> Also, while at the top, it mentions 
> 
> Macro: AC_DISABLE_FAST_INSTALL

Libtool by default has this option turned off.
The configure scripts that are generated with automake/autoconf
seem to be the ones that default to on.
I will try to make that more clear.



> 
> It does not mention how a maintainer should SET this macro, to disable
> libtoool fast-install
> 
> 
> _______________________________________________
> maintainers mailing list
> maintainers at lists.opencsw.org
> https://lists.opencsw.org/mailman/listinfo/maintainers



- --

Thanks,
Mike

"Any intelligent fool can make things bigger, more complex,
and more violent.  It takes a touch of genius -- and a lot of courage --
to move in the opposite direction."

* Albert Einstein 1879 - 1955
    US German-born Theoretical Physicist
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