Profiler: resolve top of stack address to a function

Profiler: resolve top of stack address to a function

When we cannot map top frame's pc to a code object and top frame is JS frame we now assume that it was a frameless invocation of a native function (e.g. __fmod) and try to resolve address on top of the stack into a JS function.

BUG=chromium:529931
LOG=Y

Committed: https://crrev.com/aee75623aad0af2d43135b8dbbfe948168ce2a24
Cr-Commit-Position: refs/heads/master@{#30688}

[yurys, 2015-09-10 01:33:52]

yurys@chromium.org changed reviewers:
+ alph@chromium.org

[yurys, 2015-09-10 01:33:58]

The CQ bit was checked by yurys@chromium.org to run a CQ dry run

[yurys, 2015-09-10 01:34:03]

The CQ bit was unchecked by yurys@chromium.org

[yurys, 2015-09-10 01:37:26]

The CQ bit was checked by yurys@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-09-10 01:37:34]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1315683007/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1315683007/1

[commit-bot: I haz the power, 2015-09-10 01:40:23]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-09-10 01:40:24]

Dry run: Try jobs failed on following builders:
  v8_presubmit on tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_presubmit/builds/5662)

[yurys, 2015-09-10 01:45:04]

yurys@chromium.org changed reviewers:
+ jkummerow@chromium.org

[alph, 2015-09-10 06:20:36]

lgtm

https://codereview.chromium.org/1315683007/diff/1/src/profile-generator.cc
File src/profile-generator.cc (right):

https://codereview.chromium.org/1315683007/diff/1/src/profile-generator.cc#ne...
src/profile-generator.cc:645: *entry++ = code_map_.FindEntry(sample.tos,
&start);
You can omit the second argument.

[Jakob Kummerow, 2015-09-10 10:51:06]

What happens if sample.tos is not a valid pc? For example, we might be in a
frameless stub invocation, and the stub may have pushed a value onto the stack
(which it'll pop before it returns); this happens frequently on ia32 where we
have very few registers.

LGTM if such cases don't cause trouble.

[yurys, 2015-09-10 15:58:49]

On 2015/09/10 10:51:06, Jakob wrote:
> What happens if sample.tos is not a valid pc? For example, we might be in a
> frameless stub invocation, and the stub may have pushed a value onto the stack
> (which it'll pop before it returns); this happens frequently on ia32 where we
> have very few registers.
> 
> LGTM if such cases don't cause trouble.

This is possible though seems unlikely since the value on top of the stack
should be a valid address of generated code, otherwise code_map_.FindEntry will
return NULL and we are fine. We decided that it is a reasonable trade-off.

https://codereview.chromium.org/1315683007/diff/1/src/profile-generator.cc
File src/profile-generator.cc (right):

https://codereview.chromium.org/1315683007/diff/1/src/profile-generator.cc#ne...
src/profile-generator.cc:645: *entry++ = code_map_.FindEntry(sample.tos,
&start);
On 2015/09/10 06:20:36, alph wrote:
> You can omit the second argument.

Done. Also I did more clean-up in another CL:
https://codereview.chromium.org/1332683002/

[yurys, 2015-09-10 16:01:06]

The CQ bit was checked by yurys@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-09-10 16:01:17]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1315683007/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1315683007/20001

[commit-bot: I haz the power, 2015-09-10 16:50:07]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-09-10 16:50:08]

Dry run: This issue passed the CQ dry run.

[yurys, 2015-09-10 17:43:26]

The CQ bit was checked by yurys@chromium.org

[yurys, 2015-09-10 17:43:27]

The patchset sent to the CQ was uploaded after l-g-t-m from alph@chromium.org,
jkummerow@chromium.org
Link to the patchset: https://codereview.chromium.org/1315683007/#ps20001
(title: "moved tos analysis before line number resolution")

[commit-bot: I haz the power, 2015-09-10 17:43:31]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1315683007/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1315683007/20001

[commit-bot: I haz the power, 2015-09-10 17:45:45]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-09-10 17:46:01]

Patchset 2 (id:??) landed as
https://crrev.com/aee75623aad0af2d43135b8dbbfe948168ce2a24
Cr-Commit-Position: refs/heads/master@{#30688}

[Michael Achenbach, 2015-09-21 14:01:12]

We're getting a new msan flake once in a while since this change. See e.g.:
http://build.chromium.org/p/client.v8/builders/V8%20Linux%20-%20arm64%20-%20s...
http://build.chromium.org/p/client.v8/builders/V8%20Linux%20-%20arm64%20-%20s...

Could you take a look if there's a connection?