https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113734
--- Comment #23 from Tamar Christina <tnfchris at gcc dot gnu.org> ---
small standalone reducer:
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#define N 306
#define NEEDLE 136
__attribute__ ((noipa, noinline))
int use(int x[N])
{
printf("res=%d\n", x[NEEDLE]);
return x[NEEDLE];
}
__attribute__ ((noipa, noinline))
int foo (int i, unsigned short parse_tables_n)
{
int table[N];
memset (table, -1, sizeof (table));
parse_tables_n >>= 9;
parse_tables_n += 11;
while (i < N && parse_tables_n--)
table[i++] = 0;
return use (table);
}
int main ()
{
if (foo (0, 0xFFFF) != 0)
abort ();
return 0;
}
---
> gcc incorrect.c -O3 -o incorrect.exe; and ./incorrect.exe; echo $status
res=-1
1
> gcc incorrect.c -O1 -o incorrect.exe; and ./incorrect.exe; echo $status
res=0
0
> gcc incorrect.c -O3 -fdisable-tree-cunroll -o incorrect.exe; and
> ./incorrect.exe; echo $status
res=0
0
