989011 - Factor this-computation for arrow functions out of JSOP_LAMBDA

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

[Jan de Mooij [:jandem]]

For arrow functions, js::Lambda currently uses ComputeThis to compute |this| for the current Baseline/interpreter frame.

Computing |this| for Ion frames is a bit more complicated, see IonBuilder::jsop_this.

It'd be nice if we could just emit JSOP_THIS followed by JSOP_LAMBDA_ARROW, this should also be more efficient for Baseline.

Comment 1

[Jan de Mooij [:jandem]]

Attachment: Patch

This patch adds JSOP_LAMBDA_ARROW and emits it for arrow functions. This op is always preceded by JSOP_THIS, this is nice because it means we get the (optimized) compute-this logic for free. Ion-compiling this op will be straight-forward.

It should also be slightly faster, because we no longer need the GetTopBaselineFrame stuff etc.

Comment 2

[Jason Orendorff [:jorendorff]]

Comment on attachment 8398118 [details] [diff] [review]
Patch

Review of attachment 8398118 [details] [diff] [review]:
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Looks good.

Comment 3

[Jan de Mooij [:jandem]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/5caacc7b8fa5

Pushed to Try last week for bug 989204, 'twas green.

Comment 4

[Wes Kocher (:KWierso) (Not reading bugmail; email directly if needed)]

https://hg.mozilla.org/mozilla-central/rev/5caacc7b8fa5