[PATCH 0/2] Memory corruption caused by failure to notice architecture change.

Turns out that in a particular use case insight does not spot a change
of architecture, and then starts corrupting memory by accessing off the
end of the register cache.

I've got two patches,

[1/2] - Adds an assert that would detect this bug.

[2/2] - My attempt at a fix.  I've only had a quick look over the tcl
code, (and I'm no tcl expert), so I suspect some feedback on this one.

Cheers,
Andrew