Re: [wwwdocs] gcc-13/changes.html: Document C++ -fexcess-precision=standard

[Gerald Pfeifer <gerald@pfeifer.com>]

On Thu, 9 Feb 2023, Jakub Jelinek wrote:
> Martin Liska mentioned that porting_to.html doesn't mention
> the C++ excess precision changes.  Not really sure if porting_to
> should document those, but I think changes.html certainly should.

Do you think this is a widely spread issue for existing software? Did 
it materialize a couple of times building/testing Fedora with GCC 13 
snapshots (assuming you have done so as in the past)?

> Ok for wwwdocs?

Yes, thank you! Two minor suggestions/questions below:

> --- a/htdocs/gcc-13/changes.html
> +++ b/htdocs/gcc-13/changes.html
> +      <code>-fexcess-precision=fast</code>.  The option affects mainly

Here I'd say "mainly affects".

> +      IA-32/x86-64 where when defaulting to x87 math and in some cases on
> +      Motorola 68000 <code>float</code> and <code>double</code> expressions
> +      are evaluated in <code>long double</code> precision and S/390, System z,
> +      IBM z Systems where <code>float</code> expressions are evaluated in
> +      <code>double</code> precision.

The "where when" part proved a bit tricky for my brain. :-) 

I think it is precise, but am wondering whether

  ...IA-32/x64 using x87 math and in some cases on Motorola 68000, where
  <code>float</code> and <code>double</code> expressions are evaluated...

might work? What do you think?

Gerald