| From: | Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> |
|---|---|
| To: | Ranier Vilela <ranier(dot)vf(at)gmail(dot)com> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Peter Geoghegan <pg(at)bowt(dot)ie>, Noah Misch <noah(at)leadboat(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: Clang UndefinedBehaviorSanitize (Postgres14) Detected undefined-behavior |
| Date: | 2020-08-31 17:00:50 |
| Message-ID: | 20200831170050.GA3569@alvherre.pgsql |
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| Lists: | pgsql-hackers |
On 2020-Aug-31, Ranier Vilela wrote:
> More troubles with undefined-behavior.
>
> This type of code can leaves overflow:
> var = (cast) (expression);
> diff = (int32) (id1 - id2);
>
> See:
> diff64 = ((long int) d1 - (long int) d2);
> diff64=-4294901760
Did you compile this with gcc -fwrapv?
--
Álvaro Herrera https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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