[Bug middle-end/85344] Constant constraint check sign extends unsigned constant input operands

[thopre01 at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85344

--- Comment #3 from Thomas Preud'homme <thopre01 at gcc dot gnu.org> ---
More worrying is that this code compiles without error when it should error
out:

void
foo (void)
{
  __asm( "%0" :: "J" ((unsigned char) 0x80));
}