long_by_long_mulhi() rewritten and commented

[John Rose]

(Should have CC-ed the list...)

Begin forwarded message:
From: John Rose <john.rose at sun.com>
Date: February 2, 2009 2:54:51 PM PST
To: Christian Thalinger <Christian.Thalinger at Sun.COM>
Subject: Re: Request for review (XS): 6800154: Add comments to  
long_by_long_mulhi() for better understandability

On Feb 2, 2009, at 9:40 AM, Christian Thalinger wrote:

> http://webrev.invokedynamic.info/twisti/6800154/

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.

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.

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.

Nice rewrite; thanks.

-- John

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