Disable powf/log2?f/exp2?f optimization for single-precision Arm FPU

[Corinna Vinschen]

On Jan 23 10:43, Thomas Preudhomme wrote:
> Hi,
> 
> New optimized powf, logf, log2f, expf and exp2f yield worse performance
> on Arm targets with only single precision instructions because the double
> precision arithmetic is then implemented via softfloat routines. This
> patch uses the old implementation when double precision instructions are
> not available on Arm targets.
> 
> Testing: Built newlib with GCC's rmprofile Arm multilibs and compared
> before/after -> only the above functions are changed and calls to them
> (name change from logf to __ieee754_logf and similar). Testing the
> changed function on a panel of values yields the same result before the
> original patches to improve them and after this one. Double checking the
> performance by looping the same panel of values being tested on Arm
> Cortex-M4 does show the performance regression is fixed.
> 
> Patch in git format-patch format (has anyone a better way of saying this?) attached.

Just "patch attached" because git format-patch format is standard? :)

Pushed.


Thanks,
Corinna

-- 
Corinna Vinschen
Cygwin Maintainer
Red Hat
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