Remove underflow error in float division with infinite divisor.
authorTom Lane <tgl@sss.pgh.pa.us>
Wed, 4 Nov 2020 23:11:15 +0000 (18:11 -0500)
committerTom Lane <tgl@sss.pgh.pa.us>
Wed, 4 Nov 2020 23:11:15 +0000 (18:11 -0500)
commitfac83dbd6fe1ac3d4125bfa39f287f95bffe6cda
treeb337e030c78f731557298585647d572728c3d973
parent9e38c2bb5093ceb0c04d6315ccd8975bd17add66
Remove underflow error in float division with infinite divisor.

float4_div and float8_div correctly produced zero for zero divided
by infinity, but threw an underflow error for nonzero finite values
divided by infinity.  This seems wrong; at the very least it's
inconsistent with the behavior recently implemented for numeric
infinities.  Remove the error and allow zero to be returned.

This patch also removes a useless isinf() test from the overflow
checks in these functions (non-Inf divided by Inf can't produce Inf).

Extracted from a larger patch; this seems significant outside the
context of geometric operators, so it deserves its own commit.

Kyotaro Horiguchi

Discussion: https://postgr.es/m/CAGf+fX70rWFOk5cd00uMfa__0yP+vtQg5ck7c2Onb-Yczp0URA@mail.gmail.com
src/include/utils/float.h
src/test/regress/expected/float4-misrounded-input.out
src/test/regress/expected/float4.out
src/test/regress/expected/float8.out
src/test/regress/sql/float4.sql
src/test/regress/sql/float8.sql