From: Andi Hellmund <mail@andihellmund.com>
To: kevin diggs <diggskevin38@gmail.com>
Cc: gcc-help@gcc.gnu.org
Subject: Re: options for later passes
Date: Mon, 21 Feb 2011 23:37:00 -0000 [thread overview]
Message-ID: <4D62F0C9.1010305@andihellmund.com> (raw)
In-Reply-To: <AANLkTimyLp9g+y9SXQnd2155j+8hZSaS2-AdBmnBKtY1@mail.gmail.com>
Hey Kevin,
> Is there an easy way to figure out which options need to be passed to
> later compilation passes?
Well, I think it's quite easy: it depends on what you want to build, how
you want to build it and which library it requires. For example,
gcc/linker can't know that function xyz() belongs to libabc.
> What should be used for assembly:
>
> gcc -c ??? gcc1test.s
I doubt that you really need to assemble a file directly, but it also
depends on your needs. I would say that default options (though no
specific options) could be sufficient.
> I am pretty sure the link will need the -fpic.
-fpic _should_ be used when building a shared library.
> Probably also something like -pthread?
Only, if you are building a multi-threaded application. If not, you
don't need to specify -lpthread.
> So as a general rule should it see the cpu (or arch) option?
Sorry, but this also depends. If you for example build an application to
be used by a Linux distro which might run on a various number of CPUs,
you would possible use the "generic" option, but if you are building a
high-performance application, you would specifically tune your
application for the target processor.
> Does anyone else need the -O2?
No, only the compiler (cc1, cc1plus, ...)
> P.S.: Do the order of the optimization options matter: '-O2 -mcpu=750
> -mmultiple' the same as '-mmultiple -mcpu=750 -O2'?
No, it shouldn't. GCC firstly reads in the parameter and then does a
post-processing on the options where necessary.
Best regards,
Andi
next prev parent reply other threads:[~2011-02-21 23:10 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-02-21 20:58 kevin diggs
2011-02-21 23:37 ` Andi Hellmund [this message]
2011-02-22 0:34 ` kevin diggs
2011-02-22 15:47 ` Andi Hellmund
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