This patch introduces infrastructure for the rule tree, and constructs it.
We don't use it yet, nor have good heuristics for GC'ing it, but this should not
happen anymore once we store the rule node reference in the node.
I haven't messed up with memory orders because I want to do a try run with it,
then mess with them.
Take down the ApplicableDeclarationsCache, use the rule tree for doing the cascade.
We also make sure that an element never has an ElementData with ElementDataStyles::Uninitialized,
and eagerly call prepare_for_styling whenever an ElementData is instantiated.
MozReview-Commit-ID: 9YP6eSmdMt0
Instead of maintaining a dummy restyle damage field for text nodes, we can just
perform the necessary parent inheritance and is_changed adjustments on the fly
in ThreadSafeLayoutNode, simplifying the requirements on the style system.
MozReview-Commit-ID: DCqiCRLsLUF
A couple of changes here:
* Remove the option to unset with the dirty bit setters.
* Add an explicit API for setting text node style.
* Hoist has_changed handling into the restyle damage setter and text node style setter.
* Make set_style take a non-Option.
The current semantics make it very difficult to figure out when the existing
style is mutated and what code depends on it. This is problematic for the
new incremental restyle architecture, where the cascade logic no longer has
direct access to |data|.
The cache is never effective in this case since a style attribute
adds to the set of applicable declarations.
This also avoid avoids the cache giving out-dated (incorrect) results
when `PropertyDeclarationBlock` becomes mutable in a later commit.
This is sufficient for now since CSSOM is only implemented for
`Element.style`. When StyleRule mutation is added,
some additional mechanism (such as evicting the cache) will be needed.
Flush style sharing cache on parent mismatch.
Fixes#12913. No new tests were added, but we should at least make sure existing tests still pass.
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stylo: Don't calculate restyle damage on text nodes
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Cached element class names in style sharing cache with lazy computation
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Fixes#12912
Added a field to StyleSharingCandidate to lazily compute and cache the class names.
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The style candidate cache had regressed a few times (see #12534), and my
intuition is that being able to disable all style sharing with a single rule in
the page is really unfortunate.
This commit redesigns the style sharing cache in order to be a optimistic cache,
but then reject candidates if they match different sibling-affecting selectors
in the page, for example.
So far the numbers have improved, but not so much as I'd wanted (~10%/20% of
non-incremental restyling time in general). The current implementation is really
dumb though (we recompute and re-match a lot of stuff), so we should be able to
optimise it quite a bit.
I have different ideas for improving it (that may or may not work), apart of the
low-hanging fruit like don't re-matching candidates all the time but I have to
measure the real impact.
Also, I need to verify it against try.
In the Gecko case, this style source would be the style context. In the servo
case, it will be always the computed values.
We could optimise this further in the case of stylo (from three FFI calls to
one) if we use an API of the form CalcAndStore(node, new_cv). But that would
imply borrowing the data twice from Servo (we also have borrow_data_unchecked
fwiw, but...).
