Fix finding reg-sets of call insn in collect_fn_hard_reg_usage

[Richard Henderson]

On 06/19/2014 09:40 AM, Richard Henderson wrote:
> It appears that regs_ever_live includes any register mentioned explicitly, and
> thus the only registers it doesn't contain are those killed by the callees.
> That should be an easier scan than the rtl, since we have those already
> collected in the cgraph.

And I forgot to mention it might be worth while to notice simple recursion.
Avoid the early exit path if caller == callee, despite the caller-save info not
being valid.


r~