Re: [Bug math/15384] New: One constant fewer in ieee754/dbl-64/wordsize-64/s_finite.c

["Ondřej Bílka" <neleai@seznam.cz>]

On Sun, Apr 21, 2013 at 10:06:00AM +0000, marc.glisse at normalesup dot org wrote:
> http://sourceware.org/bugzilla/show_bug.cgi?id=15384
> 
>              Bug #: 15384
>            Summary: One constant fewer in
>                     ieee754/dbl-64/wordsize-64/s_finite.c
>            Product: glibc
>            Version: unspecified
>             Status: NEW
>           Severity: enhancement
>           Priority: P2
>          Component: math
>         AssignedTo: unassigned@sourceware.org
>         ReportedBy: marc.glisse@normalesup.org
>     Classification: Unclassified
> 
> 
> Hello,
> 
> this is very minor, and I don't even know what platforms use this file, but in
> ieee754/dbl-64/wordsize-64/s_finite.c:
> 
> int
> __finite(double x)
> {
>   int64_t lx;
>   EXTRACT_WORDS64(lx,x);
>   return
> (int)((uint64_t)((lx&INT64_C(0x7fffffffffffffff))-INT64_C(0x7ff0000000000000))>>63);
> }
>
It could be simplified more. Constants are  not necessary here. I will
post patch to libc-alpha. 
> The first constant 0x7fffffffffffffff is unnecessary, it would work just as
> well with 0x7ff0000000000000, so there is only one constant loaded. The same
> applies to the 32 bit version, but for platforms like x86 that embed 32 bit
> constants in the instruction it probably wouldn't matter.
> 
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