Reduce queue size in dead code elimination by eagerly processing live instructions.

Reduce queue size in dead code elimination by eagerly processing live instructions.

BUG=
R=rmcilroy@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=17196

[titzer, 2013-10-14 12:18:53]

Measured an 7x decrease in the memory allocated in the zone during this phase,
from 2.2mb to 0.3mb on benchmarks/run.js. Shouldn't affect performance
significantly, and should generate identical code.

[rmcilroy, 2013-10-14 12:43:29]

lgtm with one nit.

Nice, thanks!

https://codereview.chromium.org/27178002/diff/1/src/hydrogen-dce.cc
File src/hydrogen-dce.cc (right):

https://codereview.chromium.org/27178002/diff/1/src/hydrogen-dce.cc#newcode35
src/hydrogen-dce.cc:35: HValue* instr, ZoneList<HValue*>* worklist) {
add an ASSERT(worklist->is_empty()) here.

[titzer, 2013-10-14 13:19:01]

On 2013/10/14 12:43:29, rmcilroy wrote:
> lgtm with one nit.
> 
> Nice, thanks!
> 
> https://codereview.chromium.org/27178002/diff/1/src/hydrogen-dce.cc
> File src/hydrogen-dce.cc (right):
> 
> https://codereview.chromium.org/27178002/diff/1/src/hydrogen-dce.cc#newcode35
> src/hydrogen-dce.cc:35: HValue* instr, ZoneList<HValue*>* worklist) {
> add an ASSERT(worklist->is_empty()) here.

I've added an ASSERT at the end of the marking phase.

[titzer, 2013-10-14 13:32:10]

Committed patchset #2 manually as r17196 (presubmit successful).