code review 7229044: runtime: implement range access functions in race detector.

runtime: implement range access functions in race detector.

Range access functions are already available in TSan library
but were not yet used.

Time for go test -race -short:

Before:
compress/flate 24.244s
exp/norm       >200s
go/printer     78.268s

After:
compress/flate 17.760s
exp/norm        5.537s
go/printer      5.738s

Fixes issue 4250.

[remyoudompheng, 2013-01-27 01:05:31]

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

I'd like you to review this change to
https://go.googlecode.com/hg/

[albert.strasheim, 2013-01-27 04:27:57]

Awesome.

The other one that needed serious help was

code.google.com/p/go.net/idna

What is the effect there?

[remyoudompheng, 2013-01-27 07:33:22]

On 2013/1/27  <fullung@gmail.com> wrote:
> Awesome.
>
> The other one that needed serious help was
>
> code.google.com/p/go.net/idna
>
> What is the effect there?
>
> https://codereview.appspot.com/7229044/

The issue is that old instrumentation of appendslice instruments the
whole slice each time.
It should distinguish between the enough capacity and
not-enough-capacity situations.

strconv.Quote makes many little appendslice, so it becomes quadratic
under race detection.

This is fixed in the patch (I hope it's correct).

Rémy.

[dvyukov, 2013-01-27 10:03:01]

Please add stubs to pkg/runtime/race0.c even if it builds now somehow.

[dvyukov, 2013-01-27 10:49:18]

https://codereview.appspot.com/7229044/diff/4001/src/pkg/runtime/slice.c
File src/pkg/runtime/slice.c (right):

https://codereview.appspot.com/7229044/diff/4001/src/pkg/runtime/slice.c#newc...
src/pkg/runtime/slice.c:84: if(m > x.cap) {
remove {}

https://codereview.appspot.com/7229044/diff/4001/src/pkg/runtime/slice.c#newc...
src/pkg/runtime/slice.c:162: runtime·racewritepc(old.array + i*t->elem->size,
pc, runtime·growslice);
perhaps also handle this one
I guess it must be race*read*

[remyoudompheng, 2013-01-27 18:21:14]

Hello dvyukov@google.com, golang-dev@googlegroups.com, fullung@gmail.com (cc:
golang-dev@googlegroups.com),

Please take another look.

[remyoudompheng, 2013-01-27 18:35:53]

https://codereview.appspot.com/7229044/diff/4001/src/pkg/runtime/slice.c
File src/pkg/runtime/slice.c (right):

https://codereview.appspot.com/7229044/diff/4001/src/pkg/runtime/slice.c#newc...
src/pkg/runtime/slice.c:84: if(m > x.cap) {
On 2013/01/27 10:49:18, dvyukov wrote:
> remove {}

Done.

https://codereview.appspot.com/7229044/diff/4001/src/pkg/runtime/slice.c#newc...
src/pkg/runtime/slice.c:134: runtime·racewriterangepc(ret.array+ret.len, y.len,
1, pc, runtime·appendslice);
fixed typo

https://codereview.appspot.com/7229044/diff/4001/src/pkg/runtime/slice.c#newc...
src/pkg/runtime/slice.c:162: runtime·racewritepc(old.array + i*t->elem->size,
pc, runtime·growslice);
On 2013/01/27 10:49:18, dvyukov wrote:
> perhaps also handle this one
> I guess it must be race*read*

Done.

https://codereview.appspot.com/7229044/diff/4001/src/pkg/runtime/slice.c#newc...
src/pkg/runtime/slice.c:263: runtime·racewriterangepc(to.array, ret, 1, pc,
runtime·appendslice);
fixed typo.

[dvyukov, 2013-01-29 11:08:19]

LGTM++
Thanks!

[remyoudompheng, 2013-01-30 00:55:15]

*** Submitted as https://code.google.com/p/go/source/detail?r=185eb42ac938 ***

runtime: implement range access functions in race detector.

Range access functions are already available in TSan library
but were not yet used.

Time for go test -race -short:

Before:
compress/flate 24.244s
exp/norm       >200s
go/printer     78.268s

After:
compress/flate 17.760s
exp/norm        5.537s
go/printer      5.738s

Fixes issue 4250.

R=dvyukov, golang-dev, fullung
CC=golang-dev
https://codereview.appspot.com/7229044