https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71567
Bug ID: 71567
Summary: Incorrect loop optimization
Product: gcc
Version: 4.8.5
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: tyoma.ariv at gmail dot com
Target Milestone: ---
#define NIN 2
struct struct1 {
char ggint[NIN][6];
char dummy;
};
/*----------------------------------------------------------------------*/
int get_struct1cnt(struct struct1 *gr)
{
int i=0 ;
for ( i=0 ; *(gr->ggint[i]) != '\0' && i < NIN ; ++i )
;
return i ;
}
/*----------------------------------------------------------------------*/
int main (int argc, char **argv)
{
struct struct1 grp = {0};
for ( int i=0 ; i < NIN ; i++ )
grp.ggint[i][0] = 'A'+i;
printf("%d\n", get_struct1cnt (&grp));
return 0;
}
When compiled with gcc -O -std=c99 one.c: the program display 1.
When compiled with gcc -std=c99 one.c: the programm display 2 as expcted
If optimization level is -Og or not, the program displays 2, if optimization
level is -O or higher, the program displays 1.
Note: removing dummy field from struct struct1 make this bug not reproducable
