These stubs are pretty large and it'd be nice if we didn't need to regenerate them for each realm.

I think the main blocker for this is the regexp-match stub because it uses a template object. We can probably change this to use the MacroAssembler object allocation code that doesn't need a template object if we load the shape from the global.

Another issue is the RegExpStatics* we currently bake in. This would have to be loaded from the global.

I noticed while looking at bug 1846777 that the regexp-match stub always allocates a match result with 16 fixed elements, which is usually going to be overkill. While we're touching this code we could look into saving a little bit of memory there.

(In reply to Iain Ireland [:iain] from comment #2)

I noticed while looking at bug 1846777 that the regexp-match stub always allocates a match result with 16 fixed elements, which is usually going to be overkill. While we're touching this code we could look into saving a little bit of memory there.

That's a good point. If we rewrite this to use createArrayWithFixedElements we can fix that pretty easily and that seems worth doing regardless. I filed bug 1847714.

This will let us share the code across realms.

The regexp stubs can be pretty large and this avoids re-generating them for each realm.

It also lets us remove JitRealm in a later patch because it's now empty.

Depends on D185910

Depends on D185911

We've migrated all shared stubs to JitZone or JitRuntime.

Depends on D185912

In MacroAssembler::checkAllocatorState we were checking if the realm has a
metadata hook, but that doesn't work if code is shared across realms.

This patch adds a counter to the zone so that we can check if any realm has a
metadata hook. We now also only check this for object allocations so that string
and bigint allocations can still use the fast path.

Depends on D185913

"PERF" key word?

https://hg.mozilla.org/mozilla-central/rev/74e34f523e79
https://hg.mozilla.org/mozilla-central/rev/46ea212278dc
https://hg.mozilla.org/mozilla-central/rev/189960592ce4
https://hg.mozilla.org/mozilla-central/rev/e9faa0ecf53d
https://hg.mozilla.org/mozilla-central/rev/6853f3c9048b