$ cat labs.c extern long int labs (long int __x) __attribute__ ((__const__));
int main() { int a,b; foo(&a, &b); if (labs(a) > b) return 1; else return 0; } is translated with $ gcc -O3 -fdump-tree-optimized -S labs.c into <bb 0>: foo (&a, &b); return (int) (ABS_EXPR <(long int) a> > (long int) b); The casts aren't necessary in this case. -- Summary: Unnecessary casts for comparison Product: gcc Version: 4.1.0 Status: UNCONFIRMED Keywords: missed-optimization Severity: enhancement Priority: P2 Component: tree-optimization AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: tkoenig at gcc dot gnu dot org CC: gcc-bugs at gcc dot gnu dot org http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22199