> Well - we usually don't grab bits off the tree nodes lightly.  Especially if
> the cgraph seems to be more fit.
>
>> If this is a suggestion, I can put it on my laundry list of future things
>> todo (after merge, 4.8?, etc).
>
> There are not many consumers of the flag, so fixing it shouldn't be hard.
> For 4.7 definitely.

Fair enough.

The following patch puts the bit in the cgraph structure.

There was a comment originally that we may be able to calculate this bit 
from the CFG, but I'm not sure whether this applies any more, or how 
much work it would be.  I left the comment in.

Tested on x86-64 Linux.

OK for branch?