Closed Bug 584293 Opened 9 years ago Closed 9 years ago

Speed up .style on HTML and XUL elements


(Core :: DOM: Core & HTML, defect, P1)




Tracking Status
blocking2.0 --- beta4+


(Reporter: bzbarsky, Assigned: bzbarsky)


(Blocks 1 open bug)



(1 file, 1 obsolete file)

As the summary says: make .style faster.  Measurements suggest the upcoming patch makes it 3.5x faster.

The change to nsXULElement::GetStyle overlaps with a similar change in bug 569719; hence the dependency.  Zack should land his stuff first.
Attached patch Fix (obsolete) — Splinter Review
Two notes:

1)  This doesn't handle SVG elements.  That's a different interface, but would be easy to do if we have a lot of free bits in the typemapping.  Do we?

2)  This is still slower than webkit.  Remaining time spent is 55% under xpc_qsXPCOMObjectToJsval (self time, time in NativeInterface2JSObject, time in FindInJSObjectScope, QI on the decl).  22% is spent in the GetStyle quickstub (a lot of this setting up the ToJsval function call with its many arguments).  5% is spent calling GetStyle on the element.  9% is spent in trace-generated code, and 6% in GetPropertyWithNativeGetter.
Attachment #462694 - Flags: review?(peterv)
Attachment #462694 - Flags: approval2.0?
Depends on: 569719
Summary: Speed up .style on HTML and XUL elements → [FIX]Speed up .style on HTML and XUL elements
Comment on attachment 462694 [details] [diff] [review]

>+nsStyledElement::GetStyle(nsresult* retval)
> {
>+  nsXULElement* xulElement = nsXULElement::FromContent(this);
>+  if (xulElement) {
>+    nsresult rv = xulElement->EnsureLocalStyle();
>+    if (NS_FAILED(rv)) {

It would be nice if EnsureLocalStyle returned void (all it throws is OUT_OF_MEMORY?). Oh well.

>   nsGenericElement::nsDOMSlots *slots = GetDOMSlots();
>+  if (!slots) {

I don't think this can happen anymore?

>diff --git a/content/html/content/src/nsGenericHTMLElement.cpp b/content/html/content/src/nsGenericHTMLElement.cpp

>+  NS_IMETHOD GetStyle(nsIDOMCSSStyleDeclaration** aStyle) {

Brace on its own line.

>diff --git a/content/xul/content/src/nsXULElement.cpp b/content/xul/content/src/nsXULElement.cpp

>+  NS_IMETHOD GetStyle(nsIDOMCSSStyleDeclaration** aStyle) {

Same here.

The bitmap has 32 bits. Adding nsSVGStylableElement looks fine to me.
Attachment #462694 - Flags: review?(peterv) → review+
> all it throws is OUT_OF_MEMORY?

I think so, but I don't think it's following infallible-only codepaths yet.  Once it is, I'd hope static analysis would win for us.

> I don't think this can happen anymore?

Indeed.  Took that null-check out.

> Brace on its own line.

Done, both places.

I added nsSVGStylableElement.
Attachment #462694 - Attachment is obsolete: true
Attachment #462819 - Flags: approval2.0?
Attachment #462694 - Flags: approval2.0?
Summary: [FIX]Speed up .style on HTML and XUL elements → Speed up .style on HTML and XUL elements
Whiteboard: [need approval]
blocking2.0: --- → beta4+
Attachment #462819 - Flags: approval2.0?
Whiteboard: [need approval] → [need landing]
Closed: 9 years ago
Flags: in-testsuite-
Resolution: --- → FIXED
Whiteboard: [need landing]
Target Milestone: --- → mozilla2.0b4
Some combination of this and bug 584287 gave us a 5% win on Dromaeo (DOM) on tinderbox on Linux and Mac.
Depends on: 585745
Depends on: 628794
Component: DOM → DOM: Core & HTML
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