Re: [Qemu-devel] [PATCH v2 02/26] armv7m: Undo armv7m.hack

[Michael Davidsaver]

On 12/17/2015 10:38 AM, Peter Maydell wrote:
> We could use a comment here (a) explaining what we're doing and (b)
> mentioning that this isn't architecturally correct -- ideally we should
> catch these exception exits on execution of the jump insn, not by
> letting the jump execute and then trapping when we actually try to
> execute at the magic addresses.

I had an instructive little digression to investigate doing things the
"right way" (in tcg).  I can see how it would be done by adding a
conditional every time the PC could be updated.  To me the unassigned
handler trick/hack seems simpler (less likely to add a bug) and avoids
emitting more code for every ldm/pop instruction.