Foating point: tracking change in between gcc 4.4.7 and gcc 4.9.2

Mathieu Malaterre mathieu.malaterre@gmail.com
Thu Dec 10 14:26:00 GMT 2015


On Thu, Dec 10, 2015 at 12:08 PM, Mathieu Malaterre
<mathieu.malaterre@gmail.com> wrote:
> Hi,
>
> I am trying to track a change in behavior in between gcc 4.4.7
> (CentOS/x86_64) and gcc 4.9.2 (fedora/x86_64). The result of a complex
> computation (floating point involved) is slightly different in between
> those two.
>
> Does anyone knows if there was a major change in floating point
> computation of std::log, std::pow, std::ceil, std::sqrt or std::exp in
> between those versions? My input is a raw binary (no ASCII parsing
> involved anywhere in the code). I've compiled code in debug on both
> side (only option -g is used nothing else).
>
> Sorry if this is very broad, I need pointer to get started.

Just for reference. I've scp'ed the executable file from CentOS over
my fedora installation and it runs as expected. So the issue is within
one of the system lib on CentOS (libc/libm/libstdc++6 ?)

-- 
Mathieu



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