pgsql: pg_attribute_no_sanitize_alignment() macro

pg_attribute_no_sanitize_alignment() macro

Modern gcc and clang compilers offer alignment sanitizers, which help to detect
pointer misalignment. However, our codebase already contains x86-specific
crc32 computation code, which uses unalignment access. Thankfully, those
compilers also support the attribute, which disables alignment sanitizers at
the function level. This commit adds pg_attribute_no_sanitize_alignment(),
which wraps this attribute, and applies it to pg_comp_crc32c_sse42() function.

Discussion: https://postgr.es/m/CAPpHfdsne3%3DT%3DfMNU45PtxdhSL_J2PjLTeS8rwKnJzUR4YNd4w%40mail.gmail.com
Discussion: https://postgr.es/m/475514.1612745257%40sss.pgh.pa.us
Author: Alexander Korotkov, revised by Tom Lane
Reviewed-by: Tom Lane

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/993bdb9f935a751935a03c80d30857150ba2b645

Modified Files
--------------
src/include/c.h | 12 ++++++++++++
src/port/pg_crc32c_sse42.c | 1 +
2 files changed, 13 insertions(+)