[Bug rtl-optimization/69887] [4.9/5/6 Regression] gcc ICE at -O1 and above on x86_64-linux-gnu in mark_jump_label_1

[ebotcazou at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69887

--- Comment #5 from Eric Botcazou <ebotcazou at gcc dot gnu.org> ---
> But we shouldn't ICE on this.  It is fine to reject it with error.

See the discussion under PR c/59039.  These builtins are undocumented and
people must know what they are doing if they use them, which is obviously not
the case here since the buffer would already be overrun...

HJ's proposed patch for PR c/59039 does document the restriction.