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Re: GCC Compiler Optimization ignores or mistreats MFENCE memory barrier related instruction
- From: Umesh Kalappa <umesh dot kalappa0 at gmail dot com>
- To: Jakub Jelinek <jakub at redhat dot com>
- Cc: Alexander Monakov <amonakov at ispras dot ru>, gcc at gcc dot gnu dot org
- Date: Tue, 29 May 2018 09:49:49 +0530
- Subject: Re: GCC Compiler Optimization ignores or mistreats MFENCE memory barrier related instruction
- References: <CAGfacvSeTBiT=zofrzZ-TvVia8t+fBo=dhNpKMnCdmAngo4nLA@mail.gmail.com> <20180507083830.GF8577@tucnak>
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
>