Closed Bug 1360523 Opened 4 years ago Closed 4 years ago
Make the number of reserved slots dynamic for proxy classes
Bug 1237504 hardcoded this to 2 but it should be trivial to change that now. It will let us shrink the size of DOM proxies because they need only 1 reserved slot instead of 2, so combined with the private slot it means we can go from an OBJECT4 allocation to OBJECT2. I also want to use a constexpr template to static_assert the number of slots <= MAX_FIXED_SLOTS.
(In reply to Jan de Mooij [:jandem] from comment #0) > I also want to use a constexpr template to static_assert the number of slots > <= MAX_FIXED_SLOTS. (Slots including the private slot, of course.)
This patch defines the number of slots explicitly for each proxy Class. We can use a constexpr template to assert a few things about our Class flags. I can compile (and start) the browser with this, fingers crossed GCC and MSVC accept this too (I'll do a Try push of course). I verified the static_assert works correctly: if I give a Proxy class 15 slots it compiles and with 16 slots compilation fails. Unfortunately I had to move this code from jsfriendapi.h to js/public/Proxy.h, because we need ProxyValueArray defined there and Proxy.h includes jsfriendapi.h. Sorry about that.
Attachment #8862889 - Flags: review?(bzbarsky)
Comment on attachment 8862889 [details] [diff] [review] Patch >+++ b/dom/base/WindowNamedPropertiesHandler.cpp >+ JSCLASS_HAS_RESERVED_SLOTS(1)), Strictly speaking, this class doesn't need any reserved slots at all. It certainly never uses them. Maybe document that we just have this to keep the SpiderMonkey asserts happy? r=me; thank you for doing this!
Attachment #8862889 - Flags: review?(bzbarsky) → review+
Thanks for the quick review! I'll add the comment and push this later today or tomorrow. (In reply to Jan de Mooij [:jandem] from comment #2) > fingers crossed GCC and MSVC accept this too They do \o/ https://treeherder.mozilla.org/#/jobs?repo=try&revision=7844b2c91af47a2051f6d11943f59ad00bdd7654&group_state=expanded
Pushed by email@example.com: https://hg.mozilla.org/integration/mozilla-inbound/rev/1d5d4015f0c1 Define number of reserved slots explicitly for each proxy js::Class. r=bz
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