605196 - Need switch to enable/disable specializations and inlining at JIT-time

Status: RESOLVED FIXED

(Tamarin Graveyard :: Baseline JIT (CodegenLIR), defect, P2)

Description

[William Maddox]

Ongoing optimization work has lead to more code paths and greater subtlety in how a given opcode or builtin is translated.  In order to rapidly isolate bugs arising from this new machinery, it should be possible to quickly disable it.

- At a minimum, there should be a way to turn off all the "fancy stuff" from the command-line to aid in bug triage.

- It would be helpful to allow fine-grained control of which optimizations are performed to facilitate performance studies.

- Inlining increases code size and puts pressure on analysis algorithms (e.g., deadvars) that are sensitive to the number of branches and labels in the code.  In some cases, we may need to fall back to a less aggressive space-for-speed tradeoff in order to control code size and/or compilation time.

Comment 1

[Edwin Smith]

Arguably we also need a mm.cfg switch for Flash.

Comment 2

[Steven Johnson]

(In reply to comment #1)
> Arguably we also need a mm.cfg switch for Flash.

mms.cfg, actually

Comment 3

[William Maddox]

Command line switches -osr and -noinline were included in tr-spicy as part of the following patches:

https://bugzilla.mozilla.org/attachment.cgi?id=489290&action=diff
https://bugzilla.mozilla.org/attachment.cgi?id=491050&action=diff

Flash mms.cfg support has also been added for these in Spicier.

Leaving the bug open until these make it into TR, and fine-grained control issues are addressed.  Retargeting for Serrano.

Comment 4

[Andre Kruetzfeldt]

Bill: is this part of the current work?

Comment 5

[William Maddox]

(In reply to comment #4)
> Bill: is this part of the current work?

The -noinline switch in tr-spicy and mentioned in comment 3 has landed in TR as part of the port of OSR from tr-spicy:

http://hg.mozilla.org/tamarin-redux/rev/ff7c627718e8

The FP work that will be needed once TR is next integrated into FRMain is covered by WE 2793437.

There is no longer any particular urgency to this bug, but it remains desirable that have more fine-grained control for performance studies.

Comment 6

[William Maddox]

Attachment: Make inlining of fused add and vector index conditional on inlineFastpath flag

TR has added an additional inlining optimization since the -Dnoinline switch and the internal inlineFastpath flag were added to tr-spicy.

The patch merely wraps an 'if (inlineFastpath)' around a couple of blocks of code that were already guarded by compile-time conditionalization -- the rest is just indentation.

Comment 7

[Rick Reitmaier]

Comment on attachment 527604 [details] [diff] [review]
Make inlining of fused add and vector index conditional on inlineFastpath flag

r+

Comment 8

[Tamarin Bot]

changeset: 6219:f432ac087cde
user:      William Maddox <[e-mail]>
summary:   Bug 605196 - followup: allow inlining enable/disable mechanism to control fused add + vector-index (r=rreitmai)

http://hg.mozilla.org/tamarin-redux/rev/f432ac087cde