Track global cells as special side effects in GVN.

Track global cells as special side effects in GVN.

R=mstarzinger@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=19713

[Benedikt Meurer, 2014-03-06 11:41:31]

Hey Michi,
This is a generalization of the inobject field tracking for GVN. It also
considers up to four global vars now.
PTAL
-- Benedikt

[Michael Starzinger, 2014-03-06 15:45:28]

LGTM with one comment.

https://codereview.chromium.org/188543004/diff/1/src/hydrogen-gvn.cc
File src/hydrogen-gvn.cc (right):

https://codereview.chromium.org/188543004/diff/1/src/hydrogen-gvn.cc#newcode453
src/hydrogen-gvn.cc:453: stream->Add("[%p]", *global_vars_[index].handle());
See comment below.

https://codereview.chromium.org/188543004/diff/1/src/hydrogen-gvn.cc#newcode479
src/hydrogen-gvn.cc:479: *cell.handle(), num_global_vars_);
Dereferencing the handle here will not work if we are on the compiler thread. We
could print the hashcode of the Unique instead. On the other hand, cells are not
relocated, so we could broaden the assert.

[Benedikt Meurer, 2014-03-07 06:23:58]

https://codereview.chromium.org/188543004/diff/1/src/hydrogen-gvn.cc
File src/hydrogen-gvn.cc (right):

https://codereview.chromium.org/188543004/diff/1/src/hydrogen-gvn.cc#newcode453
src/hydrogen-gvn.cc:453: stream->Add("[%p]", *global_vars_[index].handle());
On 2014/03/06 15:45:28, Michael Starzinger wrote:
> See comment below.

Done.

https://codereview.chromium.org/188543004/diff/1/src/hydrogen-gvn.cc#newcode479
src/hydrogen-gvn.cc:479: *cell.handle(), num_global_vars_);
On 2014/03/06 15:45:28, Michael Starzinger wrote:
> Dereferencing the handle here will not work if we are on the compiler thread.
We
> could print the hashcode of the Unique instead. On the other hand, cells are
not
> relocated, so we could broaden the assert.

Done.

[Benedikt Meurer, 2014-03-07 10:14:10]

Committed patchset #2 manually as r19713 (presubmit successful).