On 06/03/2016 02:26 PM, Torvald Riegel wrote:
On Fri, 2016-06-03 at 12:03 +0200, Jakub Jelinek wrote:
I guess it is a tough decision. If you don't have HW instruction to read
say double word aligned integer atomically, if you don't implement atomic
load on it through compare and swap (which ind
On 06/03/2016 05:32 AM, Jakub Jelinek wrote:
A change from wide CAS to locking would be an ABI change I suppose, but
it could also be considered a necessary bugfix if we don't want to write
to read-only memory. Does this affect anything but i686?
Also x86_64 (for 128-bit atomics), clearly also
On Fri, 2016-06-03 at 13:46 +0100, Kyrill Tkachov wrote:
> Hi Jakub, Torvald,
>
> On 03/06/16 13:32, Jakub Jelinek wrote:
> > On Fri, Jun 03, 2016 at 02:26:09PM +0200, Torvald Riegel wrote:
> >> And that would be fine, IMO. If you can't even load atomically, doing
> >> something useful with this
On Fri, 2016-06-03 at 14:32 +0200, Jakub Jelinek wrote:
> On Fri, Jun 03, 2016 at 02:26:09PM +0200, Torvald Riegel wrote:
> > And that would be fine, IMO. If you can't even load atomically, doing
> > something useful with this type will be hard except in special cases.
> > Also, doing a CAS (compa
Hi Jakub, Torvald,
On 03/06/16 13:32, Jakub Jelinek wrote:
On Fri, Jun 03, 2016 at 02:26:09PM +0200, Torvald Riegel wrote:
And that would be fine, IMO. If you can't even load atomically, doing
something useful with this type will be hard except in special cases.
Also, doing a CAS (compare-and-
On Fri, Jun 03, 2016 at 02:26:09PM +0200, Torvald Riegel wrote:
> And that would be fine, IMO. If you can't even load atomically, doing
> something useful with this type will be hard except in special cases.
> Also, doing a CAS (compare-and-swap) and thus potentially bringing in
> the cache line i
On Fri, 2016-06-03 at 12:03 +0200, Jakub Jelinek wrote:
> On Fri, Jun 03, 2016 at 10:34:15AM +0100, Kyrill Tkachov wrote:
> > expand_atomic_load in optabs.c tries to expand a wide atomic load using an
> > atomic_compare_and_swap
> > with the comment saying that sometimes a redundant harmless store
On Fri, Jun 03, 2016 at 10:34:15AM +0100, Kyrill Tkachov wrote:
> expand_atomic_load in optabs.c tries to expand a wide atomic load using an
> atomic_compare_and_swap
> with the comment saying that sometimes a redundant harmless store may be
> performed.
> Is the store really valid if the memory
