JSStackFrame Evisceration

This would leave sizeof(JSStackFrame) == 6 words.

Members to remove

Sorted in estimated order of benefit / difficulty:

Task Size (wks) Assignee Note
argc/argv/fun/script/thisv 3 lw Requires StackSegment changes.
ncode 3 dvander 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.
annotation 3 sayrer Trivial if we can remove callers in nsScriptSecurityManager. Alas, that is not trivial, so this is going to take a while.
callerVersion .5 cdleary Mostly the challenge is just understanding the actual use case.
XblockChain 1 A bit tricky
rval 1 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.
imacpc 1 cdleary Leave uninitialized in call path and use JSStackFrame::flags to indicate whether there is or is not an imacpc.

Method-jit changes

  • PIC for fast natives calls
  • PIC/fast path for interpreted inline call