Re: DEFAULT CFLAGS SETTING
On Thursday March 08, 2007 at 07:45:06 (PM) Christian Walther wrote: CFLAGS can be defined in /etc/make.conf My CFLAGS is set to -O2 -pipe. You might want to take a look at CPUTYPE, too. This can be set to match your CPU type, which means you'll get the most of it. You can find some examples in /usr/share/examples/etc/make.conf Thanks, but that is not exactly what I was looking for. I was attempting to find out what the default setting is in FreeBSD-6.2. I heard it was '02' but I have not been able to confirm that. -- Gerard ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: DEFAULT CFLAGS SETTING
On Fri, 09 Mar 2007 07:53:00 -0500 Gerard [EMAIL PROTECTED] wrote: On Thursday March 08, 2007 at 07:45:06 (PM) Christian Walther wrote: CFLAGS can be defined in /etc/make.conf My CFLAGS is set to -O2 -pipe. You might want to take a look at CPUTYPE, too. This can be set to match your CPU type, which means you'll get the most of it. You can find some examples in /usr/share/examples/etc/make.conf Thanks, but that is not exactly what I was looking for. I was attempting to find out what the default setting is in FreeBSD-6.2. I heard it was '02' but I have not been able to confirm that. In my case: $ make -V CFLAGS -O2 -fno-strict-aliasing -pipe -march=athlon-mp but run it on your own machine as it depends on what you set as CPUTYPE in make.conf ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: DEFAULT CFLAGS SETTING
On Thu, 08 Mar 2007 21:04:50 -0800 Garrett Cooper [EMAIL PROTECTED] wrote: Christian Walther wrote: On 08/03/07, White Hat [EMAIL PROTECTED] wrote: What is the default CFLAGS setting in FBSD-6.2 and would it improve performance any to set CFLAGS=Os as opposed to the default setting? CFLAGS can be defined in /etc/make.conf My CFLAGS is set to -O2 -pipe. Note that by explicitly defining CFLAGS, you override the -fno-strict-aliasing that's set by default. FreeBSD provides sensible defaults for all of these things, based on CPUTYPE. As mentioned when I asked the question a while back, be careful about how you optimize freebsd. ... I was told to add -fno-strict-aliasing, ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: DEFAULT CFLAGS SETTING
On 09/03/07, RW [EMAIL PROTECTED] wrote: On Thu, 08 Mar 2007 21:04:50 -0800 Garrett Cooper [EMAIL PROTECTED] wrote: Christian Walther wrote: On 08/03/07, White Hat [EMAIL PROTECTED] wrote: [...] CFLAGS can be defined in /etc/make.conf My CFLAGS is set to -O2 -pipe. Note that by explicitly defining CFLAGS, you override the -fno-strict-aliasing that's set by default. FreeBSD provides sensible defaults for all of these things, based on CPUTYPE. Thanks for pointing this out. I did read /usr/share/examples/etc/make.conf to get some sensible settings, which is why I've chosen it to set CFLAGS like I did. Since -fno-strict-aliasing is that important, it should probably be mentioned in /usr/share/examples/etc/make.conf Just my 2 cents Christian ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
DEFAULT CFLAGS SETTING
What is the default CFLAGS setting in FBSD-6.2 and would it improve performance any to set CFLAGS=Os as opposed to the default setting? -- White Hat [EMAIL PROTECTED] Not only is life a bItch, it has puppies. Adrienne E. Gusoff We won't tell. Get more on shows you hate to love (and love to hate): Yahoo! TV's Guilty Pleasures list. http://tv.yahoo.com/collections/265 ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: DEFAULT CFLAGS SETTING
On 08/03/07, White Hat [EMAIL PROTECTED] wrote: What is the default CFLAGS setting in FBSD-6.2 and would it improve performance any to set CFLAGS=Os as opposed to the default setting? CFLAGS can be defined in /etc/make.conf My CFLAGS is set to -O2 -pipe. You might want to take a look at CPUTYPE, too. This can be set to match your CPU type, which means you'll get the most of it. You can find some examples in /usr/share/examples/etc/make.conf HTH Christian ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: DEFAULT CFLAGS SETTING
Christian Walther wrote:
On 08/03/07, White Hat [EMAIL PROTECTED] wrote:
What is the default CFLAGS setting in FBSD-6.2 and would it improve
performance any to set
CFLAGS=Os
as opposed to the default setting?
CFLAGS can be defined in /etc/make.conf
My CFLAGS is set to -O2 -pipe. You might want to take a look at
CPUTYPE, too. This can be set to match your CPU type, which means
you'll get the most of it.
You can find some examples in /usr/share/examples/etc/make.conf
HTH
Christian
As mentioned when I asked the question a while back, be careful about
how you optimize freebsd. Adding additional options beyond -O2 -pipe
-fno-strict-aliasing isn't really supported so much and is discouraged
by many on this list (AFAIK) and a lot of people on the hackers@ list
(that I do know). Unlike some linux distributions where using CFLAGS and
CXXFLAGS are encouraged, it's discouraged here because it generates a
lot more variation in having to check through errors, and many times the
levels of optimization used my system users is counterproductive to the
purpose of optimizing.
I was told to add -fno-strict-aliasing, because it's an option to allow
some programs and code compile that are improperly developed or use
deprecated code / features.
From gcc(1):
-fstrict-aliasing
Allows the compiler to assume the strictest aliasing rules
applicable to the language being compiled. For C (and C++),
this activates optimizations based on the type of
expressions. In particular, an object of one type is assumed
never to reside at the same address as an object of a
different type, unless the types are almost the same. For
example, an unsigned int can alias an int, but not a
void* or a double. A character type may alias any other
type.
Pay special attention to code like this:
union a_union {
int i;
double d;
};
int f() {
a_union t;
t.d = 3.0;
return t.i;
}
The practice of reading from a different union member than
the one most recently written to (called ``type-punning'') is
common. Even with -fstrict-aliasing, type-punning is
allowed, provided the memory is accessed through the union
type. So, the code above will work as expected. However,
this code might not:
int f() {
a_union t;
int* ip;
t.d = 3.0;
ip = t.i;
return *ip;
}
Every language that wishes to perform language-specific alias
analysis should define a function that computes, given an
tree node, an alias set for the node. Nodes in different
alias sets are not allowed to alias. For an example, see the
C front-end function c_get_alias_set.
Enabled at levels -O2, -O3, -Os.
Just provide inverse logic of the above set of statements.
Definitely set CPUTYPE though--this will help since it gets passed to
gcc as -march=$CPUTYPE. However, since the version of gcc the base
system works with isn't bleeding edge it won't support all processor
types / optimizations available in later versions of gcc. There is an
examples of a make.conf file in /usr/share/etc/make.conf.example.
-Garrett
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