Improve inobject field tracking during GVN.

Improve inobject field tracking during GVN.

Now stores to inobject fields do no longer prevent hoisting
and combining of loads from other inobject fields.

R=mstarzinger@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=19249

[Benedikt Meurer, 2014-02-10 12:39:10]

Hey Michi,
As discussed offline... this is mostly mechanic refactoring to allow for
separate change/depends on flags in HValues. The interesting stuff is the
SideEffects(Scope) in GVN, which extends the current flag tracking to support
special handling for HLoadNamedField and HStoreNamedField with inobject field
accesses.
PTAL
-- Benedikt

[Michael Starzinger, 2014-02-10 14:50:07]

LGTM, only nits.

https://codereview.chromium.org/144423010/diff/1/src/hydrogen-gvn.h
File src/hydrogen-gvn.h (right):

https://codereview.chromium.org/144423010/diff/1/src/hydrogen-gvn.h#newcode39
src/hydrogen-gvn.h:39: class SideEffects V8_FINAL {
A comment that this is merely a GVNFlagSet plus "special" dynamic side effects
and why we need that would be nice.

https://codereview.chromium.org/144423010/diff/1/src/hydrogen-gvn.h#newcode77
src/hydrogen-gvn.h:77: class SideEffectsScope V8_FINAL BASE_EMBEDDED {
Can we have a few comments above this class to explain what it is used for? Also
the name is misleading IMHO, as it sounds like several of these scopes are
stacked (which they aren't). It is only used to track finer-grained side-effects
for loads and stores. How about calling it SideEffectsMap (my favorite),
SideEffectsCache or SideEffectsTracker instead?

[Benedikt Meurer, 2014-02-11 06:40:54]

https://codereview.chromium.org/144423010/diff/1/src/hydrogen-gvn.h
File src/hydrogen-gvn.h (right):

https://codereview.chromium.org/144423010/diff/1/src/hydrogen-gvn.h#newcode39
src/hydrogen-gvn.h:39: class SideEffects V8_FINAL {
On 2014/02/10 14:50:07, Michael Starzinger wrote:
> A comment that this is merely a GVNFlagSet plus "special" dynamic side effects
> and why we need that would be nice.

Done.

https://codereview.chromium.org/144423010/diff/1/src/hydrogen-gvn.h#newcode77
src/hydrogen-gvn.h:77: class SideEffectsScope V8_FINAL BASE_EMBEDDED {
Done.

Went for SideEffectsTracker, because we already have a HSideEffectsMap.

[Benedikt Meurer, 2014-02-11 06:41:15]

Committed patchset #2 manually as r19247 (presubmit successful).

[Benedikt Meurer, 2014-02-11 06:53:22]

Committed patchset #3 manually as r19249 (presubmit successful).