In general, deleting a property from a fast-properties object
requires transitioning the object to dictionary mode. However,
when the most-recently-added property is deleted, we can simply
roll back the last map transition that the object went through.
This is a performance experiment: it should make things faster,
but if it turns out to have more negative than positive impact,
we will have to revert it.
TBR=bmeurer@chromium.org (just adding a comment)
Previously reviewed at https://codereview.chromium.org/2830093002
Previously landed as 98acfb36e1 / r44799
Review-Url: https://codereview.chromium.org/2840583002
Cr-Commit-Position: refs/heads/master@{#44808}
In general, deleting a property from a fast-properties object
requires transitioning the object to dictionary mode. However,
when the most-recently-added property is deleted, we can simply
roll back the last map transition that the object went through.
This is a performance experiment: it should make things faster,
but if it turns out to have more negative than positive impact,
we will have to revert it.
TBR=bmeurer@chromium.org (just adding a comment)
Review-Url: https://codereview.chromium.org/2830093002
Cr-Commit-Position: refs/heads/master@{#44799}
Adding properties to prototypes is faster when we don't force their
maps into fast mode yet. Once a prototype shows up in the IC system,
its setup phase is likely over, and it makes sense to transition it
to fast properties.
This patch speeds up the microbenchmark in the bug by 20x.
Octane-Typescript sees a 3% improvement.
BUG=chromium:607010
Review-Url: https://codereview.chromium.org/2036493006
Cr-Commit-Position: refs/heads/master@{#36828}
