[PATCH, alpha]: Wrap {un,}aligned_store sequence with memory blockages.

[Uros Bizjak]

On Mon, Jul 7, 2014 at 5:01 PM, Richard Henderson <rth@redhat.com> wrote:

> Early alpha can't store sub-4-byte quantities.  Altivec can't store anything
> but 16 byte quantities.  In order to perform smaller stores, we have to do a
> read-modify-write sequence on a larger aligned chunk of memory.  Two such RMW
> sequences must conflict, lest we interleave and thus bork the operation.
>
> I don't recall how much we ever did for this, exactly, but it's certainly
> possible to know that some memory operations cannot conflict with these RMW
> sequence.  E.g. through size + alignment of the other memory operation.  E.g.
> on Alpha, a byte RMW store can't conflict with a normal DImode memory access.
>
>> Btw, if the mem is MEM_READONLY_P how can it be part of
>> a {un}aligned_store sequence?
>
> Er... that's an excellent question.  Uros?

This flag is copied from the original memory operand by
alpha_set_memflags to all memory operands in the expanded sequence.

Uros.