487482 - Implement policy for flushing and reusing JIT code memory

Status: RESOLVED WONTFIX

(Tamarin Graveyard :: Baseline JIT (CodegenLIR), defect)

Description

[Edwin Smith]

Tracking bug for adding support for flushing cold code from jit memory

Comment 1

[Edwin Smith]

Attachment: use premark() callback to flush jitted code that isn't active on stack.

* depends on the patches that are in dependent bugs.
* conservative mark-sweep of stack to find active code.
* known bug: the ExceptionHandlers object from jitted code sticks around when method is later interpreted.

Comment 2

[Edwin Smith]

working repo is
http://hg.mozilla.org/users/edwsmith_adobe.com/users/deopt

Comment 3

[Tom Harwood]

Found the repo at http://hg.mozilla.org/users/edwsmith_adobe.com/deopt

Comment 4

[Lars T Hansen]

Comment on attachment 376272 [details] [diff] [review]
use premark() callback to flush jitted code that isn't active on stack.

Looks reasonable to me.

(In sweep, the accounting only needs happen for verbose code, which may matter if CodeAlloc::size is anything but trivial.

Another performance hack is that if sweeping will discard all unmarked methods /and/ there is an expectation of many active methods so that sweep has relatively low efficiency then you can dispense with sweeping altogether by having the marker unlink pinned methods from the method list (and add them to a secondary list); sweeping then just deletes everything remaining on the list and swaps in the secondary list for the first list.  But that seems minor.)

Comment 5

[Lars T Hansen]

Status on this?

Comment 6

[Edwin Smith]

Work in progress in these repos:
https://hg.mozilla.org/users/edwsmith_adobe.com/deopt
https://hg.mozilla.org/users/edwsmith_adobe.com/fragmentation
https://hg.mozilla.org/users/edwsmith_adobe.com/second-jit

all are ~3 months stale and need rebasing.

* CodeAlloc fragmentation has been addressed in tamarin-redux
* pointer classification may no longer be necessary; new MethodFrame gives us a way to exactly walk the AS3 stack and mark jit'd functions.

Comment 7

[Michael Kohler [:mkohler]]

This is a mass change. Every comment has "assigned-to-new" in it.

I didn't look through the bugs, so I'm sorry if I change a bug which shouldn't be changed. But I guess these bugs are just bugs that were once assigned and people forgot to change the Status back when unassigning.

Comment 8

[Sylvestre Ledru [:Sylvestre]]

Tamarin is a dead project now. Mass WONTFIX.

Comment 9

[Sylvestre Ledru [:Sylvestre]]

Tamarin isn't maintained anymore. WONTFIX remaining bugs.