GCC Compiler Optimization ignores or mistreats MFENCE memory barrier related instruction

[Umesh Kalappa]

Ok, thanks for the clarification jakub.

Umesg

On Mon, May 7, 2018, 2:08 PM Jakub Jelinek <jakub@redhat.com> wrote:

> On Mon, May 07, 2018 at 01:58:48PM +0530, Umesh Kalappa wrote:
> > CCed Jakub,
>
> > > Agree that float division don't touch memory ,but fdiv  result (stack
> > > register ) is stored  back to a memory i.e fResult .
>
> That doesn't really matter.  It is stored to a stack spill slot, something
> that doesn't have address taken and other code (e.g. in other threads)
> can't
> in a valid program access it.  That is not considered memory for the
> inline-asm, only objects that must live in memory count.
>
>         Jakub
>