code review 12650045: cmd/gc: move large stack variables to heap

cmd/gc: move large stack variables to heap

Individual variables bigger than 10 MB are now
moved to the heap, as if they had escaped on
their own.

This avoids ridiculous stacks for programs that
do things like
        x := [1<<30]byte{}
        ... use x ...

If 10 MB is too small, we can raise the limit.

Fixes issue 6077.

[rsc, 2013-08-08 17:46:28]

Hello ken2 (cc: golang-dev@googlegroups.com),

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

[rsc, 2013-08-08 17:46:33]

*** Submitted as https://code.google.com/p/go/source/detail?r=29b6246f5a9c ***

cmd/gc: move large stack variables to heap

Individual variables bigger than 10 MB are now
moved to the heap, as if they had escaped on
their own.

This avoids ridiculous stacks for programs that
do things like
        x := [1<<30]byte{}
        ... use x ...

If 10 MB is too small, we can raise the limit.

Fixes issue 6077.

R=ken2
CC=golang-dev
https://codereview.appspot.com/12650045

[bradfitz, 2013-08-08 17:58:17]

This also fixes part of Issue 6036



On Thu, Aug 8, 2013 at 10:46 AM, <rsc@golang.org> wrote:

> Reviewers: ken2,
>
> Message:
> Hello ken2 (cc: golang-dev@googlegroups.com),
>
> I'd like you to review this change to
> https://code.google.com/p/go/
>
>
> Description:
> cmd/gc: move large stack variables to heap
>
> Individual variables bigger than 10 MB are now
> moved to the heap, as if they had escaped on
> their own.
>
> This avoids ridiculous stacks for programs that
> do things like
>         x := [1<<30]byte{}
>         ... use x ...
>
> If 10 MB is too small, we can raise the limit.
>
> Fixes issue 6077.
>
> Please review this at
https://codereview.appspot.**com/12650045/<https://codereview.appspot.com/126...
>
> Affected files:
>   M src/cmd/gc/go.h
>   M src/cmd/gc/lex.c
>   M src/cmd/gc/pgen.c
>   M test/escape5.go
>   M test/fixedbugs/bug385_64.go
>
>
> --
>
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> To unsubscribe from this group and stop receiving emails from it, send an
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> .
>
>
>

[ken3, 2013-08-08 18:13:49]

On 2013/08/08 17:58:17, bradfitz wrote:
> This also fixes part of Issue 6036
> 
> 
> 
> On Thu, Aug 8, 2013 at 10:46 AM, <mailto:rsc@golang.org> wrote:
> 
> > Reviewers: ken2,
> >
> > Message:
> > Hello ken2 (cc: mailto:golang-dev@googlegroups.com),
> >
> > I'd like you to review this change to
> > https://code.google.com/p/go/
> >
> >
> > Description:
> > cmd/gc: move large stack variables to heap
> >
> > Individual variables bigger than 10 MB are now
> > moved to the heap, as if they had escaped on
> > their own.
> >
> > This avoids ridiculous stacks for programs that
> > do things like
> >         x := [1<<30]byte{}
> >         ... use x ...
> >
> > If 10 MB is too small, we can raise the limit.
> >
> > Fixes issue 6077.
> >
> > Please review this at
>
https://codereview.appspot.**com/12650045/%3Chttps://codereview.appspot.com/1...>
> >
> > Affected files:
> >   M src/cmd/gc/go.h
> >   M src/cmd/gc/lex.c
> >   M src/cmd/gc/pgen.c
> >   M test/escape5.go
> >   M test/fixedbugs/bug385_64.go
> >
> >
> > --
> >
> > ---You received this message because you are subscribed to the Google
> > Groups "golang-dev" group.
> > To unsubscribe from this group and stop receiving emails from it, send an
> > email to
>
mailto:golang-dev+unsubscribe@**googlegroups.com<golang-dev%2Bunsubscribe@googlegroups.com>
> > .
> > For more options, visit
>
https://groups.google.com/**groups/opt_out%3Chttps://groups.google.com/groups...>
> > .
> >
> >
> >

lgtm

10m seems fine, maybe even a
little large.