[PATCH] Fix ifcvt ICE

[Eric Botcazou]

> So this patch is quite simple: implement two replacement functions
> find_active_insn_before/after() that correct the above mentioned
> behavior, and use them in ifcvt.

OK on principle, but the implementation isn't fully correct because it uses 
BLOCK_FOR_INSN and this isn't defined for BARRIERs.

Please add a BB parameter to both functions and test against BB_HEAD or BB_END 
to stop the iteration, like in first_active_insn/last_active_insn.

-- 
Eric Botcazou