pgsql: Use branchless comparisons in btint4cmp and btint8cmp, for speed

Use branchless comparisons in btint4cmp and btint8cmp, for speed

The comment on pg_cmp_*() points out that the old form can produce
better code if the comparison is inlined, but that's not a concern
here because btint4cmp() and btint8cmp() are invoked through the
function manager and won't be inlined.

Author: David Geier <geidav(dot)pg(at)gmail(dot)com>
Reviewed-by: Matthias van de Meent <boekewurm+postgres(at)gmail(dot)com>
Reviewed-by: Kirill Reshke <reshkekirill(at)gmail(dot)com>
Reviewed-by: Japin Li <japinli(at)hotmail(dot)com>
Discussion: https://www.postgresql.org/message-id/5d366878-2007-4d31-861e-19294b7a583b@gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/41467b1d88303fbaea4ddd20c21ac4b8ce6b92d7

Modified Files
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src/backend/access/nbtree/nbtcompare.c | 15 +++------------
1 file changed, 3 insertions(+), 12 deletions(-)