Re: Test suite fails on alpha architecture

Falk Hueffner <falk(at)debian(dot)org> writes:
> Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:
>> It looks to me like Debian's compiler must be allowing the division
>> instruction to be speculatively executed before the if-test branch
>> is taken.

> Can you create a stand-alone testcase for this?

I don't have access to a machine on which the failure occurs, but
perhaps Martin can try it. I'd think it'd be pretty easy, say

#include <stdio.h>
#include <stdlib.h>

void
ereport(const char *msg)
{
fprintf(stderr, "%s\n", msg);
exit(0);
}

int
main(int argc, char **argv)
{
int arg1 = atoi(argv[1]);
int arg2 = atoi(argv[2]);
int result;

if (arg2 == 0)
ereport("division by zero");

result = arg1 / arg2;

printf("%d\n", result);

return 0;
}

cc -g -O2 -fPIC -fno-strict-aliasing -mieee -D_GNU_SOURCE bug.c
./a.out 1 0

I would not be surprised at all if it's compile-switch dependent; these
look to be the switches Martin tested with.

regards, tom lane