code review 98640043: runtime: improve stack frame layout comment

runtime: improve stack frame layout comment
The idea is as follows:
- each line (except +------------------+) represents a word of memory
- regions that can consist of several words occupy several lines
- variables (argp/varp/sp) point with <- at first/last word of the region (instead of "somewhere in between")
It's much more readable for me in this form. Does it make sense to you?

[dvyukov, 2014-05-27 17:55:14]

Hello golang-codereviews@googlegroups.com (cc: khr@golang.org, rsc@golang.org),

I'd like you to review this change to
https://dvyukov%40google.com@code.google.com/p/go/

[r, 2014-05-27 18:23:39]

LGTM
I like this but wait to see if rsc and khr agree

[khr1, 2014-05-27 19:53:15]

I'm still a fan of having sp/argp/varp be borders between regions, not
pointing to any particular word.



On Tue, May 27, 2014 at 11:23 AM, <r@golang.org> wrote:

> LGTM
> I like this but wait to see if rsc and khr agree
>
> https://codereview.appspot.com/98640043/
>

[dvyukov, 2014-05-27 21:00:55]

But it's not possible for a pointer to point in between words. It can point
either at last word of locals or first word of args. This is critical for
checking for off-by-one bugs.
I've especially made these regions 3 lines, so it's also clear close to what
boundary a pointer points to.


On 2014/05/27 19:53:15, khr1 wrote:
> I'm still a fan of having sp/argp/varp be borders between regions, not
> pointing to any particular word.
> 
> 
> 
> On Tue, May 27, 2014 at 11:23 AM, <mailto:r@golang.org> wrote:
> 
> > LGTM
> > I like this but wait to see if rsc and khr agree
> >
> > https://codereview.appspot.com/98640043/
> >

[rsc, 2014-05-27 22:58:29]

not lgtm

pointers between words do make sense. the rewrite is not obviously better, so we
should leave it as is.

[rsc, 2014-05-27 22:59:06]

if you want to read the picture as pointing to the very beginning of the word,
do so. 
it doesn't point into the middle of the word, which is what the rewrite looks
like.

[dvyukov, 2014-06-10 19:05:27]

*** Abandoned ***