Optimization of Array.push()

[dan1wang]

After I reported Issue #3211, I discovered Closure Compiler (ADVANCED_OPTIMIZATIONS) also doesn't optimize push().

I had

      obj.arrayProp.push( offsetSegment(mask, offsetX, 0) );
      obj.arrayProp.push( offsetSegment(mirroredMask, offsetX, 0) );

and I get

a.f.push(offsetSegment(c,d,0)),
a.f.push(offsetSegment(h,d,0)),

instead of
a.f.push(offsetSegment(c,d,0),offsetSegment(h,d,0)),

[tjgq]

Created Google internal issue b/123406223

[ChadKillingsworth]

This would be a pretty good first contribution. It can be done with a peephole optimization.

[cshung]

I wanted to attempt this one.

[brad4d]

Once I looked more closely at the PR proposed to fix this issue, I realized it wasn't really an optimization we should add.

From the discussion on that PR:

Overall this optimization doesn't strike me as a very useful one.
It's not likely that a human author would put a lot of array.push(), right next to each other,
so I'd think this would only be useful if other optimizations ended up putting them together, which
then allowed this optimization to do something useful. That also seems likely to be a rare thing to me.

Execution time is precious for large projects.