[Bug tree-optimization/38789] [4.4 Regression] __builtin_constant_p appears to eveluate to true for non-constant arguments.

[daney at gcc dot gnu dot org]

------- Comment #5 from daney at gcc dot gnu dot org  2009-01-09 22:00 -------
You have to be able to do one of the original test case or this:

$ cat foo1.c

void baz(int v)
{
        unsigned a;

        a = (v == 1) ? 1 : 2;

        if (__builtin_constant_p(a)) {
                asm volatile ("you lose. %0" : : "i" (a));
        } else {
                asm volatile ("you win. %0" : : "i" (a));
        }
}
$ gcc -O2 -S foo1.c
foo1.c: In function ‘baz’:
foo1.c:9: warning: asm operand 0 probably doesn’t match constraints
foo1.c:9: error: impossible constraint in ‘asm’


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38789