[ARM] Fix PR49641

[Bernd Schmidt]

On 10/18/11 14:30, Richard Earnshaw wrote:
> Well, if that's the case why do we need to test for Thumb1 at all?  And
> why do we only enable write-back for Thumb1?  other ISA variants can
> also do that (I know that Thumb1 requires write-back, but it's
> optionally available for the other ISA flavours).

We're not trying to generate a writeback sequence with our peepholes.
The problem is that on Thumb, that's the only instruction available, and
we want to make use of it if possible (i.e. register dead afterwards etc.).


Bernd