Turn dead code elimination into a proper HPhase.

Turn dead code elimination into a proper HPhase.

R=dslomov@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=15529

[Dmitry Lomov (no reviews), 2013-07-05 19:06:20]

https://codereview.chromium.org/18791002/diff/1/src/hydrogen-dce.h
File src/hydrogen-dce.h (right):

https://codereview.chromium.org/18791002/diff/1/src/hydrogen-dce.h#newcode53
src/hydrogen-dce.h:53: ZoneList<HValue*> worklist_;
It looks like the uses of worklist_ inside MarkLiveInstructions and
RemoveDeadInstructions are completely independent, and they both assert that
they start with empty worklist.
Let's not introduce the state where there is no state - keep worklist local to
each function and pass it to MarkLive. Maybe even better, make MarkList return
boolean and keep addition to worklist local to MarkLiveInstructions.

[Benedikt Meurer, 2013-07-06 07:30:42]

https://codereview.chromium.org/18791002/diff/1/src/hydrogen-dce.h
File src/hydrogen-dce.h (right):

https://codereview.chromium.org/18791002/diff/1/src/hydrogen-dce.h#newcode53
src/hydrogen-dce.h:53: ZoneList<HValue*> worklist_;
On 2013/07/05 19:06:20, Dmitry Lomov (chromium) wrote:
> It looks like the uses of worklist_ inside MarkLiveInstructions and
> RemoveDeadInstructions are completely independent, and they both assert that
> they start with empty worklist.
> Let's not introduce the state where there is no state - keep worklist local to
> each function and pass it to MarkLive. Maybe even better, make MarkList return
> boolean and keep addition to worklist local to MarkLiveInstructions.

Done.

[Dmitry Lomov (no reviews), 2013-07-07 00:09:22]

lgtm

[Benedikt Meurer, 2013-07-07 06:00:23]

Committed patchset #2 manually as r15529 (presubmit successful).