Commit Graph

1 Commits

Author SHA1 Message Date
Jaroslav Sevcik
06ba822ead Map update for integrity level transitions.
This adds support for integrity level transitions (preventExtensions,
seal and freeze) to MapUpdater and Map::TryUpdate.

In both cases, we first try to detect whether there were integrity
level transitions in the transition tree to the old map and make note
of the most restrictive integrity transition and the map just before
the transition (integrity-source-map). Then we find an appropriate root
(based on integrity-source-map's elements kind) and replay the
transitions based on the integrity-source-map's descriptor
array. Finally, if we saw an integrity level transition in
the beginning, we will find-or-create that transition (on the
updated version of integrity-source-map).

For the following micro-benchmark, we get about 10x speedup.

```
function C() {
  this.x = 1;
  Object.seal(this);
  this.x = 0.1;
}

const start = Date.now();
for (let i = 0; i < 1e7; i++) {
  new C();
}
console.log("Reconfigure sealed: " + (Date.now() - start));
```

Before:
> Reconfigure sealed: 5202

After:
> Reconfigure sealed: 479

Bug: v8:8538
Change-Id: If695be7469d8b6ccd44ac4528be8aa34b65b3e4d
Reviewed-on: https://chromium-review.googlesource.com/c/1442640
Commit-Queue: Jaroslav Sevcik <jarin@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59295}
2019-02-01 14:28:57 +00:00