[Bug c/126552] const-qualified local register variable used as an asm operand is silently discarded

[bernie at codewiz dot org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126552

--- Comment #12 from Bernie Innocenti <bernie at codewiz dot org> ---
Would a diagnostic or a warning for code like this be possible?

  const PLANEPTR v2 = 0L;
  register const PLANEPTR n2 __asm("a0") = v2;

Tracking down the silent argument corruption took a long time, since in most
cases a0 randomly happened to contain 0.