Add MSVC support for pg_leftmost_one_pos32() and friends
To allow testing for general support for fast bitscan intrinsics,
add symbols HAVE_BITSCAN_REVERSE and HAVE_BITSCAN_FORWARD.
Also do related cleanup in AllocSetFreeIndex(): Previously, we
tested for HAVE__BUILTIN_CLZ and copied the relevant internals of
pg_leftmost_one_pos32(), with a special fallback that does less
work than the general fallback for that function. Now that we have
a more general test, we just call pg_leftmost_one_pos32() directly
for platforms with intrinsic support. On gcc at least, there is no
difference in the binary for non-assert builds.
Discussion:
https://www.postgresql.org/message-id/CAFBsxsEPc%2BFnX_0vmmQ5DHv60sk4rL_RZJ%2BMD6ei%3D76L0kFMvA%40mail.gmail.com
Branch
------
master
Details
-------
https://git.postgresql.org/pg/commitdiff/67731974644ce77129d282434065c3f0be04be92
Modified Files
--------------
src/backend/utils/mmgr/aset.c | 6 ++--
src/include/port/pg_bitutils.h | 75 +++++++++++++++++++++++++++++++++++++-----
2 files changed, 70 insertions(+), 11 deletions(-)