Horton

Re: pgsql: Provide overflow safe integer math inline functions.

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andres Freund <andres@anarazel.de>
Cc: pgsql-committers@postgresql.org, Michael Paquier <michael.paquier@gmail.com>
Date: 2017-12-17T01:31:01Z
Lists: pgsql-hackers 
Andres Freund <andres@anarazel.de> writes:
> I'm not quite following. Could you check if the same happens without
> -O2? Not because that'd be a solution, but to narrow down how this
> happens?

The committed test looks quite broken to me: it's missing some &
operators.  Not sure how that translates into failing to fail the
configure test, but personally I'd have done this like

volatile PG_INT64_TYPE a = 1;
volatile PG_INT64_TYPE b = 1;
PG_INT64_TYPE result;
__builtin_mul_overflow(a, b, &result);

			regards, tom lane

Commits

  1. Try harder to detect unavailability of __builtin_mul_overflow(int64).

  2. Try to detect runtime unavailability of __builtin_mul_overflow(int64).

  3. Fix a number of copy & paste comment errors in common/int.h.

  4. Provide overflow safe integer math inline functions.