CVS commit: src/lib/libm/src

["Taylor R Campbell" <riastradh%netbsd.org@localhost>]

Module Name:    src
Committed By:   riastradh
Date:           Sat May  4 19:21:51 UTC 2024

Modified Files:
        src/lib/libm/src: s_rintl.c

Log Message:
s_rintl.c: Reduce FreeBSD diff and fix on ld128 platforms.

EXT_FRACBITS, the number of bits in the _binary encoding_ that stores
the trailing significand field, is never 113.  In IEEE 754 binary128,
it is 112, even though there are 113 bits of precision in the set of
floating-point numbers -- the leading 1 bit is implicit in binary128.
So ld128 platforms like aarch64 and sparc64 were skipping the real
definition and just defining rintl as an alias for rint, which is
wrong.

In contrast, LDBL_MANT_DIG, the number of bits of precision in the set
of floating-point numbers (p, in IEEE 754 parlance), is 113 in IEEE 754
binary128.  This is also the constant used in FreeBSD libm anyway.  So
let's just use that instead of trying to translate it to our private
EXT_FRACBITS (not defined in FreeBSD) with a fencepos terror.  And
delete the buggy rintl=rint alias.

PR lib/58054


To generate a diff of this commit:
cvs rdiff -u -r1.6 -r1.7 src/lib/libm/src/s_rintl.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.