https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101938
Bug ID: 101938
Summary: [12 Regression] Wrong code with -fwrapv since
r12-2591-g2e96b5f14e402569
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Keywords: wrong-code
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: marxin at gcc dot gnu.org
CC: aldyh at gcc dot gnu.org, amacleod at redhat dot com
Target Milestone: ---
It's a test-case reduced from postgresql package:
$ cat postgresql.c
#include <stdio.h>
typedef long long int int64;
#define INT64CONST(x) (x##LL)
#define PG_INT64_MIN (-INT64CONST(0x7FFFFFFFFFFFFFFF) - 1)
static int64
__attribute__((noipa))
int8gcd_internal(int64 arg1, int64 arg2)
{
int64 swap;
int64 a1,
a2;
/*
* Put the greater absolute value in arg1.
*
* This would happen automatically in the loop below, but avoids an
* expensive modulo operation, and simplifies the special-case handling
* for INT64_MIN below.
*
* We do this in negative space in order to handle INT64_MIN.
*/
a1 = (arg1 < 0) ? arg1 : -arg1;
a2 = (arg2 < 0) ? arg2 : -arg2;
if (a1 > a2)
{
swap = arg1;
arg1 = arg2;
arg2 = swap;
}
/* Special care needs to be taken with INT64_MIN. See comments above.
*/
if (arg1 == PG_INT64_MIN)
{
if (arg2 == 0 || arg2 == PG_INT64_MIN)
{
__builtin_printf ("ret=out of range\n");
}
/*
* Some machines throw a floating-point exception for INT64_MIN
% -1,
* which is a bit silly since the correct answer is perfectly
* well-defined, namely zero. Guard against this and just
return the
* result, gcd(INT64_MIN, -1) = 1.
*/
if (arg2 == -1) {
__builtin_printf ("ret=%d\n", 1);
return 1;
}
}
/* Use the Euclidean algorithm to find the GCD */
while (arg2 != 0)
{
swap = arg2;
arg2 = arg1 % arg2;
arg1 = swap;
}
/*
* Make sure the result is positive. (We know we don't have INT64_MIN
* anymore).
*/
if (arg1 < 0)
arg1 = -arg1;
__builtin_printf ("ret=%lld\n", arg1);
return arg1;
}
int main()
{
int8gcd_internal (-1, -9223372036854775808ULL);
return 0;
}
$ gcc postgresql.c -fwrapv && ./a.out
ret=1
$ gcc postgresql.c -O2 -fwrapv && ./a.out
Floating point exception (core dumped)
