[wwwdocs] GCC processor independent install?

[wwwdocs] GCC processor independent install?

[Vru Inbvi]

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Hi,

If I install for instance Ubuntu 22.04 with the default compilers (from apt
install) on computers with AMD and Intel processors, and run my application
I get the same results, bit for bit.

However if I install a different version of GCC and GFORTRAN from source I
get different results.

Which configuration options should I use make my install
processor-independent and get the same results?

VI

Re: [wwwdocs] GCC processor independent install?

[Gabriel Ravier]

On 2/26/24 21:59, Vru Inbvi via Gcc-help wrote:
> Hi,
>
> If I install for instance Ubuntu 22.04 with the default compilers (from apt
> install) on computers with AMD and Intel processors, and run my application
> I get the same results, bit for bit.
>
> However if I install a different version of GCC and GFORTRAN from source I
> get different results.
>
> Which configuration options should I use make my install
> processor-independent and get the same results?
>
> VI


I don't exactly understand what it is you're trying to say here, 
exactly...  If you're installing different versions of GCC (e.g. GCC 12 
and GCC 13) then I would hope it is obvious enough that the different 
versions will pretty much always output different code - even for minor 
version updates this can often occur. If the issue is that your 
application appears to exhibit different behavior (and not just have 
differing executable artifacts) depending on the version this is most 
likely due to a bug in your program, which you might be able to find 
using checkers like `-fsanitize` or others, or, much less likely, there 
is a bug in one of the two versions of GCC you used to compile the code.