long_by_long_mulhi() rewritten and commented

[Christian Thalinger]

On Mon, 2009-02-02 at 15:05 -0800, John Rose wrote:

> A couple of comments:
> > + Node *v1 = phase->longcon(magic_const >> N / 2);
> 
> should be:
> > + Node* v1 = phase->longcon(magic_const >> (N / 2));
> 
> We use parens liberally, especially when the operator precedences are
> not from simple algebra.

Good point.

> 
> Also (this is more of a judgement call for you) when renovating code,
> I suggest moving toward the majority style "T* " instead of "T *", the
> latter of which is peculiar to old opto code.

Normally I use T* but I thought HotSpot code does it differently.  I
will change that and use it from now on.

> 
> I spot-checked the details, but did not prove equivalence.  I would
> run a few test cases before and after the change, and look at the
> disassembled code to be sure all is well.

Yeah, I will run some tests in a minute.

-- Christian