Re: [PATCH] intXshr, intXshl: return error on shift count out of range - Mailing list pgsql-hackers

David Rowley <dgrowleyml@gmail.com> writes:
> Have you actually tested this on RISC-V?  Can you share the results of:
> SELECT 1::bigint << 255, 1::bigint << 63;
> Does it actually crash?

I tried this on the gcc compile farm's cfarm95 (said to be 
a Banana Pi BPI-F3 with Spacemit(R) X60 chip; runs Debian trixie).
I see no crash and results consistent with the low-six-bits rule:

regression=# SELECT 1::bigint << 255, 1::bigint << 63;
       ?column?       |       ?column?       
----------------------+----------------------
 -9223372036854775808 | -9223372036854775808
(1 row)

regression=# SELECT 1::bigint << 64, 1::bigint << (-1);
 ?column? |       ?column?       
----------+----------------------
        1 | -9223372036854775808
(1 row)

I rather imagine you can make it crash if you use ASAN configured to
dump core on whatever behavior it considers undefined ... but I
reject the notion that we should let ASAN dictate our choices here.

            regards, tom lane