| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | pgsql-committers(at)lists(dot)postgresql(dot)org |
| Subject: | pgsql: Frob numeric.c loop so that clang will auto-vectorize it too. |
| Date: | 2020-09-07 16:03:09 |
| Message-ID: | E1kFJbp-0002kt-AS@gemulon.postgresql.org |
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| Lists: | pgsql-committers |
Frob numeric.c loop so that clang will auto-vectorize it too.
Experimentation shows that clang will auto-vectorize the critical
multiplication loop if the termination condition is written "i2 < limit"
rather than "i2 <= limit". This seems unbelievably stupid, but I've
reproduced it on both clang 9.0.1 (RHEL8) and 11.0.3 (macOS Catalina).
gcc doesn't care, so tweak the code to do it that way.
Discussion: https://postgr.es/m/CAJ3gD9evtA_vBo+WMYMyT-u=keHX7-r8p2w7OSRfXf42LTwCZQ@mail.gmail.com
Branch
------
master
Details
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https://git.postgresql.org/pg/commitdiff/9c79e646c6f0f8df06d966c536d0c6aa33bf1b06
Modified Files
--------------
src/backend/utils/adt/numeric.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)
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