ping x3 : latch mem to reg before multi-access in convert_move

[Olivier Hainque <hainque at adacore dot com>]

Hello,

ping # 3 for http://gcc.gnu.org/ml/gcc-patches/2012-04/msg00298.html

This is related to convert-move possibly emitting a sequence
with multiple accesses to one input, triggering multiple memory
accesses when that input happens to be a mem.

> The original problem we had with this was the introduction of an
> artificial race condition in addition to the potential performance
> impact.

> While our original testcases don't expose the problem with current
> versions of the compiler, the issue appears to remain latent and the
> change still looks sensible in any case.
...
>       * expr.c (convert_move): Latch mem integer inputs into a
>       register before expanding a multi-instructions sequence.

Thanks in advance,

Olivier