This is the mail archive of the
gcc-help@gcc.gnu.org
mailing list for the GCC project.
Re: Ask for help
- From: Andrew Haley <aph at redhat dot com>
- To: wanxia dot wei at unb dot ca
- Cc: gcc-help at gcc dot gnu dot org
- Date: Tue, 17 Mar 2009 14:51:06 +0000
- Subject: Re: Ask for help
- References: <1237301131.49bfb78bd12ec@webmail.unb.ca>
Wei, Wanxia wrote:
> Dear Sir/Madam:
>
> I am sorry I met a problem when I used gcc to compile my C program and ran the
> executables on servers. I compiled my C program with the following two different ways
> with different options.
>
> gcc -m32 -O3 -DNDEBUG -fno-strict-aliasing -static âlm
>
> gcc -m32 âO3 âlm
>
> My problem is that the two executables obtained by using the above two ways have the
> same performance on some inputs but have different performance on other inputs.
I'd expect that. -fno-strict-aliasing has some performance impact.
> If two executables with different options should always have the same performance,
Certainly not, no, especially when one of the options controls optimization.
Andrew.