- Extract core StringPrototypeRepeat code into a TFS builtin (StringRepeat)
- Assumes arguments are a string and smi (no range checks)
- Add StringPrototypePadStart and StringPrototypePadEnd TFJ builtins
- Added StringPadAssembler to ensure common behavior
- Removed functionality from string.js
A quick benchmark shows significant performance gains for unoptimized
code (2.1x to 2.46x) and optimized code (1.03x - 1.56x).
https: //github.com/peterwmwong/v8-perf/blob/master/string-pad/README.md
Bug: v8:5049
Change-Id: I6e4fe99fb62a3edb3d6906fd4f78b3576b5b0d13
Reviewed-on: https://chromium-review.googlesource.com/720067
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48595}
The attached chromium bug suggests that turning this on via a flag
regressed a perf test. Having previously run into slowdowns due
to experimental JS natives, my suspicion is that this regression
can be fixed by including the new builtins in the snapshot.
My intention is to land this patch to see if the regression
goes away on the bots.
Given the nature of this feature, it seems low-risk to remove
the runtime flag. If need be, it would be trivial to craft
a patch to remove these two methods from String.prototype
if we run into web compat issues during the release (note
that no release branch has yet picked up this feature).
BUG=v8:4954, chromium:677444
Review-Url: https://codereview.chromium.org/2610853010
Cr-Commit-Position: refs/heads/master@{#42111}
Return the empty string from StringPad if the filler argument is the empty
string, effectively returning the string unchanged in StringPadStart and
StringPadEnd.
```
"foo".padStart(100000, "") -> "foo"
```
BUG=v8:4957, v8:4954
LOG=N
R=littledan@chromium.org
Review-Url: https://codereview.chromium.org/1926773003
Cr-Commit-Position: refs/heads/master@{#35837}
