pgsql: Combine two flag tests in GetSnapshotData().

Combine two flag tests in GetSnapshotData().

Previously the code checked PROC_IN_LOGICAL_DECODING and
PROC_IN_VACUUM separately. As the relevant variable is marked as
volatile, the compiler cannot combine the two tests. As
GetSnapshotData() is pretty hot in a number of workloads, it's
worthwhile to fix that.

It'd also be a good idea to get rid of the volatiles altogether. But
for one that's a larger patch, and for another, the code after this
change still seems at least as easy to read as before.

Author: Andres Freund
Discussion: https://postgr.es/m/20181005172955.wyjb4fzcdzqtaxjq@alap3.anarazel.de

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/5fde047f2b41e71706d4ea9e8eb0a401f64192c1

Modified Files
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src/backend/storage/ipc/procarray.c | 11 ++++-------
1 file changed, 4 insertions(+), 7 deletions(-)