Qsort swap code aliases the sorted array elements to ints and longs in
order to do swap by machine words. Unfortunately this breaks with the
full code optimization, e.g. LTO.
See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83201 which seems to
reference code directly copied from libc/stdlib/qsort.c.
PR: 228780
Reported by: mliska@suse.cz
Reviewed by: brooks
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
Differential revision: https://reviews.freebsd.org/D15714
Mainly focus on files that use BSD 3-Clause license.
The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.
Special thanks to Wind River for providing access to "The Duke of
Highlander" tool: an older (2014) run over FreeBSD tree was useful as a
starting point.
always perform recursion on the left partition, then use a tail call to
handle the right partition. In the worst case this could require O(N)
levels of recursions.
Reduce the possible recursion level to log2(N) by always recursing on the
smaller partition instead.
Obtained from: PostgreSQL 9d6077abf9d6efd992a59f05ef5aba981ea32096
Implement a small enhancement to the original qsort implementation:
If the data is 32 bit aligned we can side-step the long type
version and use int instead.
The change brings a modest but significant improvement in
32 bit workloads.
Relnotes: yes
PR: 135718
Taken from: ache
into slowsort for some sequences because different parts of the
code used 'r' to store two different things, one of which was
signed. Clean things up by splitting 'r' into two variables, and
use a more meaningful name.
This will make a number of things easier in the future, as well as (finally!)
avoiding the Id-smashing problem which has plagued developers for so long.
Boy, I'm glad we're not using sup anymore. This update would have been
insane otherwise.
