[Bug c/59615] "asm goto" output or at least clobbered operands

[hpa at zytor dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59615

--- Comment #5 from H. Peter Anvin <hpa at zytor dot com> ---
Please don't get hung up on the specific example; I just picked one that was
small and self-contained.

The biggest reason we can't use gcc's native bits in the kernel are items where
we have to use the kernel's "alternative" feature, where the code is
dynamically patched.