Oleg Goldshmidt wrote:
Nzer Zaidenberg <[EMAIL PROTECTED]> writes:
you would say that you expect problems when mixing -ffast-math with
-O9 and optimization?
I wouldn't, but gcc info would:
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.
I do believe you have mis-read the info page.
What the info page said is that no combination of -O will turn on
-ffast-math (or any of its related options). The reason for this is that
-ffast-math changes the way certain functions behave, which means that
program that rely on, for example, sqrt setting errno will not work when
-ffast-math is on. As the compiler cannot know whether your program is
like that or not, it cannot turn fast-math on for a generic optimization
level, such as -O9.
What it does *not* mean, however, is that *you* should expect problems,
should *you* turn it on. If you know your program does not rely on any
functionality that is disabled by fast-math, you can safely turn it on,
and should not expect problems, whether or not you are also using a -O
level.
Shachar
--
Shachar Shemesh
Lingnu Open Source Consulting ltd.
http://www.lingnu.com/
=================================================================
To unsubscribe, send mail to [EMAIL PROTECTED] with
the word "unsubscribe" in the message body, e.g., run the command
echo unsubscribe | mail [EMAIL PROTECTED]
