[PATCH v3] explicit_bzero yet again

[Zack Weinberg]

On Mon, Dec 7, 2015 at 10:18 AM, Szabolcs Nagy <szabolcs.nagy@arm.com> wrote:
> On 07/12/15 14:13, Zack Weinberg wrote:
>> On 11/19/2015 10:55 AM, Rich Felker wrote:
>>>
>>> Perhaps glibc explicitly does not support LTO, but with LTO this is
>>> trivially removable by the compiler. IMO from the beginning there
>>> should be asm constraints to make it impossible to remove the code
>>> even if it's inlined.
>>
>> Presently there *is* no such asm construct [...] However, presently no
>> compiler will LTO-optimize across shared library boundaries [...]
>
> obviously the concern is about static linking.

That didn't occur to me at all.

glibc explicitly doesn't support being statically linked, but I prefer
to keep it working where possible -- unfortunately, as I said, there
is no existing asm construct or compiler intrinsic that fits the bill.
I'd _like_ there to be something like
__builtin_use_memory(untyped-pointer, size) but I don't have time to
implement it myself -- this project is already way, way over the time
budget I originally allocated it -- and in any case it would only
become available in bleeding-edge compilers.

zw