Bug 20827

Summary:

the 'typeof' operator is slow

Product:

WebKit

Reporter:

Cameron Zwarich (cpst) <zwarich>

Component:

JavaScriptCore

Assignee:

Cameron Zwarich (cpst) <zwarich>

Status:

RESOLVED FIXED

Severity:

Normal

Priority:

Version:

528+ (Nightly build)

Hardware:

All

OS:

All

Bug Depends on:

Bug Blocks:

20813

Attachments:

Description	Flags
Proposed patch	none
Proposed patch with ChangeLog	none
Proposed patch with ChangeLog	mjs: review+

Description Cameron Zwarich (cpst) 2008-09-13 02:40:43 PDT

The 'typeof' operator now accounts for about 4.7% of the Shark profile of the V8 Earley-Boyer benchmark. We should look at optimizing it, probably taking advantage of StructureIDs. A lot of the examples in Earley-Boyer are of the form

typeof <expression> == <string>

We can optimize these using a peephole optimization in CodeGenerator and some new opcodes. I'll assign this to myself.

Comment 1 Cameron Zwarich (cpst) 2008-09-14 01:26:55 PDT

Created attachment 23407 [details]
Proposed patch

This patch is a 6% speedup on Earley-Boyer, but it unfortunately triggers the Richards compilation-related badness on my machine. I will try again soon.

Comment 2 Cameron Zwarich (cpst) 2008-09-14 16:24:30 PDT

Created attachment 23423 [details]
Proposed patch with ChangeLog

Comment 3 Cameron Zwarich (cpst) 2008-09-14 16:25:06 PDT

Comment on attachment 23423 [details]
Proposed patch with ChangeLog

Oops, I posted the wrong typeof patch.

Comment 4 Cameron Zwarich (cpst) 2008-09-14 16:26:06 PDT

Created attachment 23424 [details]
Proposed patch with ChangeLog

Comment 5 Maciej Stachowiak 2008-09-14 16:58:09 PDT

Comment on attachment 23424 [details]
Proposed patch with ChangeLog

r=me subject to comments from IRC.

Comment 6 Cameron Zwarich (cpst) 2008-09-14 17:26:43 PDT

Landed with requested changes in r36412.