Re: [patch, Fortran] Fix PR 125914, suboptimal code for (-1.0)**integer(8)

Hello Harald,

Regarding the check for __builtin_powi in power_6.f90: I think it is
fair to check that it is no longer in the optimized dump, but
inlined; therefore I left it in.

> I find your testcase power_10.f90 quite interesting.  It rather tests
> floating-point arithmetic and may fail at different optimization levels
> because of tests like
> 
> +  if (s4 /= 2.30965209) stop 11
> (plus several more).
> 
> Please convince yourself and also test with other compilers.
> Either add a suitable tolerance, or just test what needs to be
> tested.

You're right. While standard Fortran and IEEE semantics would
dictate that this always passes, it may not with -ffast-matth.

I was also surprised to see that ifx (on godbolt) failed one
test with optimization due to a small delta. I actually think
this is an ifx bug, but I changed the test lines to

   if (abs (s8 - 2.3096522811663198_8) > 1e-13_8) stop 3

   if (abs (s4 -  2.30965209) > 1e-5) stop 14

respectively.

Committed as https://gcc.gnu.org/g:5b0da09f0ed5da80734c143d3ce2bacd78dc0c28

Thanks for the helpful review!

Best regards

	Thomas