JSStackFrame Evisceration: Difference between revisions

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| Requires StackSegment [https://bugzilla.mozilla.org/show_bug.cgi?id=579183 changes].
| Requires StackSegment [https://bugzilla.mozilla.org/show_bug.cgi?id=579183 changes].
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|-
| ncode
| [https://bugzilla.mozilla.org/show_bug.cgi?id=595073 ncode]
| 3
| 3
| dvander/bhackett
| dvander/bhackett
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| A bit tricky
| A bit tricky
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|-
| [https://bugzilla.mozilla.org/show_bug.cgi?id=550639 rval]
| [https://bugzilla.mozilla.org/show_bug.cgi?id=595073 rval]
| 1
| 1
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| Probably more trouble than its worth to remove, just lazily initialize with a JSStackFrame::flags bit and avoid ever writing in the hot JM call/return paths.
| Lazily initialize with a JSStackFrame::flags bit and avoid ever writing in the hot JM call/return paths.
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|-
| X[https://bugzilla.mozilla.org/show_bug.cgi?id=586358 imacpc]
| X[https://bugzilla.mozilla.org/show_bug.cgi?id=586358 imacpc]

Revision as of 04:50, 10 September 2010

This leaves sizeof(JSStackFrame) == 10 words (11 on 32-bit), but we only need to initialize 5 of those words on the call path; the rest can be lazily (or never) initialized.

Members to remove

Sorted in estimated order of benefit / difficulty:

Task Size (wks) Assignee Note
Xargc/argv/fun/script/thisv 3 lw Requires StackSegment changes.
ncode 3 dvander/bhackett Merge it with savedPC in method-jit. Requires building map HW PC --> bytecode (which we sortof already heave
XdisplaySave 1 cdleary Remove display optimization for great justice!
XhookData .1 Lazily initialize using JSStackFrame::flags. Included in bug 539144.
Xannotation 3 sayrer Trivial if we can remove callers in nsScriptSecurityManager. Alas, that is not trivial, so this is going to take a while. For now, we lazily initialize which gives practically all the benefit.
XcallerVersion .5 cdleary Mostly the challenge is just understanding the actual use case.
XblockChain 1 A bit tricky
rval 1 Lazily initialize with a JSStackFrame::flags bit and avoid ever writing in the hot JM call/return paths.
Ximacpc 1 cdleary Leave uninitialized in call path and use JSStackFrame::flags to indicate whether there is or is not an imacpc.