[PATCH v2] Convert mantissa storage in mp_no to int

[Carlos O'Donell]

On 12/20/2012 09:48 PM, Siddhesh Poyarekar wrote:
> Hi,
> 
> Here's v2 of the patch with the problem of truncation of an
> intermediate value fixed as Joseph pointed out.  The code is not used
> by i386, so I couldn't test it to see it break and then fixed.
> 
> Siddhesh
> 
> ChangeLog:
> 
> 2012-12-21  Siddhesh Poyarekar  <siddhesh@redhat.com>
> 
> 	* sysdeps/ieee754/dbl-64/mpa.c (I_RADIX): New macro.
> 	(TWOPOW): Likewise.
> 	(__acr): Juggle logic a bit to make it faster and use int
> 	instead of doubles.
> 	(__mp_dbl): Use int values instead of double.
> 	(__dbl_mp): Likewise.
> 	(add_magnitudes): Likewise.
> 	(sub_magnitudes): Likewise.
> 	(__add): Likewise.
> 	(__sub): Likewise.
> 	(__mul): Likewise.
> 	* sysdeps/ieee754/dbl-64/mpa.h (mp_no): Change type of D to int
> 	array.
> 	* sysdeps/ieee754/dbl-64/mpa.c (__mpatan): Use int values
> 	instead of double.
> 	* sysdeps/ieee754/dbl-64/mpatan2.c (__mpatan2): Likewise.
> 	* sysdeps/ieee754/dbl-64/mpexp.c (__mpexp): Likewise.
> 	* sysdeps/ieee754/dbl-64/mpsqrt.c (__mpsqrt): Likewise.
> 	* sysdeps/ieee754/dbl-64/mptan.c (__mptan): Likewise.
> 	* sysdeps/ieee754/dbl-64/sincos32.c (__c32): Likewise.
> 	(__mpranred): Likewise.
> 	* sysdeps/ieee754/dbl-64/sincos32.h (oofac27): Likewise.
> 	(pi): Likewise.
> 	(hp): Likewise.
> 	* sysdeps/ieee754/dbl-64/slowpow.c (__slowpow): Likewise.

This looks good to me.

Is Power using this code?

What does the performance look like there?

I'm getting more nervous of these kinds of micro-optimizations
in isolation without a global view of our libm performance.

I'd really like to see more progress on a libm micro-benchmark
that we can use to see how these changes impact *ALL* of the
functions in libm. At a minimum we need to test the inputs 
identified in the current testsuite.

Cheers,
Carlos.