543119 - typed array tracing should be more const than it is

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

[Vladimir Vukicevic [:vlad] [:vladv] (needinfo me, slow to respond)]

Attachment: use const loads where appropriate

Many of the components involved in typed arrays (classword, length, data pointer) are actually constant per object and so should be loaded using ldc variants so that CSE can take full effect.

Doing this is a massive perf speedup -- my matrix mult benchmark goes from 250ms -> 140ms.  (Native SSE2-optimized C++ code is around 30ms.)

Comment 1

[Andreas Gal :gal]

Comment on attachment 424328 [details] [diff] [review]
use const loads where appropriate

Comment with link to better cse bug and explanation would be nice.

Comment 2

[Vladimir Vukicevic [:vlad] [:vladv] (needinfo me, slow to respond)]

http://hg.mozilla.org/tracemonkey/rev/a8dc506b2460

Comment 3

[Brendan Eich [:brendan]]

Attachment: cleanup, share source of TR::guardClass instead of copy/pasting it with ldcp tweak; else after return; RETURN_STOP_A; etc.

Converted old STOBJ_GET_CLASS(obj) to obj->getClass() too.

/be

Comment 4

[Brendan Eich [:brendan]]

Do you want a typed-array JSOP_LENGTH special case in the interpreter (jsops.cpp)?

/be

Comment 5

[Vladimir Vukicevic [:vlad] [:vladv] (needinfo me, slow to respond)]

Comment on attachment 424514 [details] [diff] [review]
cleanup, share source of TR::guardClass instead of copy/pasting it with ldcp tweak; else after return; RETURN_STOP_A; etc.

Probably should special-case it in the interpreter as well for consistency.. I can do the patch shortly.

Comment 6

[Brendan Eich [:brendan]]

Followup:

http://hg.mozilla.org/tracemonkey/rev/a24c3eeac2f3

/be