[PATCH v2] Use integer constants in mpa.c

[Ondřej Bílka]

On Tue, Mar 26, 2013 at 07:19:23PM +0530, Siddhesh Poyarekar wrote:
> hi,
> 
> Here's v2 of this patch, which is much simpler.  The patch replaces
> all instances of constant doubles to their integer counterparts.  This
> is good for architectures that benefit from using an integral mantissa
> since the compiler ends up adding additional instructions to perform
> operations in fp mode when the constants are expressed as doubles.
> powerpc (which is currently the only arch that uses double mantissa)
> sees no appreciable difference due to this patch since the compiler is
> smart enough to use the double form of the constants in this case.
> 
> No regressions noted as a result of this change and a ~10% improvement
> in performance in x86_64 as seen in the benchmark.  OK to commit?
>
Did you try compile with latest gcc? In some parts it is optimization
that gcc should do. I am not entirely sure where it is possible due sNAN
but gcc should certainly transform assignments.
> Siddhesh
> 
> 	* sysdeps/ieee754/dbl-64/mpa.c (__acr): Use integral
> 	constants.
> 	(norm): Likewise.
> 	(denorm): Likewise.
> 	(__dbl_mp): Likewise.
> 	(add_magnitudes): Likewise.
> 	(sub_magnitudes): Likewise.
> 	(__add): Likewise.
> 	(__sub): Likewise.
> 	(__mul): Likewise.
> 	(__sqr): Likewise.
> 	(__inv): Likewise.
> 	(__dvd): Likewise.
>