On Mon, Oct 30, 2017 at 4:57 PM, Andres Freund <and...@anarazel.de> wrote: > 0001) Introduces pg_{add,sub,mul}{16,32,64}_overflow(a, b, *result) > These use compiler intrinsics on gcc/clang. If that's not > available, they cast to a wider type and to overflow checks. For > 64bit there's a fallback for the case 128bit math is not > available (here I stole from an old patch of Greg's). > > These fallbacks are, as far as I can tell, C free of overflow > related undefined behaviour.
Looks nice. > Perhaps it should rather be pg_add_s32_overflow, or a similar > naming scheme? Not sure what the s is supposed to be? Signed? > 0002) Converts int.c, int8.c and a smattering of other functions to use > the new facilities. This removes a fair amount of code. > > It might make sense to split this up further, but right now that's > the set of functions that either are affected performancewise by > previous overflow checks, and/or relied on wraparound > overflow. There's probably more places, but this is what I found > by visual inspection and compiler warnings. I lack the patience to review this tonight. > 0003) Removes -fwrapv. I'm *NOT* suggesting we apply this right now, but > it seems like an important test for the new facilities. Without > 0002, tests would fail after this, after it all tests run > successfully. I suggest that if we think we don't need -fwrapv any more, we ought to remove it. Otherwise, we won't find out if we're wrong. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers