498986 - Remove Float Cache

Status: RESOLVED FIXED

(Core :: Layout: Floats, defect)

Description

[fantasai]

roc proposed to remove nsFloatCache &co and store the region on the float frame itself. A bit on nsLineBox would say whether float placeholders exist on the line, to optimize RecoverFloats and other lookups.

RecoverFloats and the CheckPlaceholderInLine call seem to be the main places nsFloatCache is used.
http://mxr.mozilla.org/mozilla-central/source/layout/generic/nsBlockFrame.cpp#3997

Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

The bug assignee is inactive on Bugzilla, so the assignee is being reset.

Comment 2

[Ting-Yu Lin [:TYLin] (PDT, UTC-7)]

Attachment: Bug 498986 Part 1 - Use nsTArray<nsIFrame*> to store float list in nsLineBox and BlockReflowState.

Nowadays, nsFloatCache stores no extra information but nsIFrame*, which makes
nsFloatCacheList and nsFloatCacheFreeList are just singly and Doubly linked
list of frames, respectively.

Most of this patch is a plain rewrite to use nsTArray APIs. There are two
rewrite that need more explanation.

1. BlockReflowState::mFloatCacheFreeList is served as a temporarily list to
   avoid extra allocations of nsFloatCache. It takes the ownership of floats
   from a line via FreeFloats(), and later reuses the cache in AddFloat().
   We don't need this anymore, so we remove it.

2. In PlaceBelowCurrentLineFloats(), the old code removes a float which
   needs to be pushed to next continuation from mBelowCurrentLineFloats.
   After looking through all of the floats, the remaining of
   mBelowCurrentLineFloats are moved to the line because they belong to the
   line. In this patch, rather than removing the pushed floats one by one from
   mBelowCurrentLineFloats, I use a new list to collect the floats that need
   to be added to the line, and just clear mBelowCurrentLineFloats at the
   end of the method.

Comment 3

[Ting-Yu Lin [:TYLin] (PDT, UTC-7)]

Attachment: Bug 498986 Part 2 - Remove unused nsFloatCache, nsFloatCacheList, and nsFloatCacheFreeList.

Also, remove unused LINE_MAX_CHILD_COUNT in nsLineBox.h

Depends on D157976

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/9f2279973623
Part 1 - Use nsTArray<nsIFrame*> to store float list in nsLineBox and BlockReflowState. r=emilio
https://hg.mozilla.org/integration/autoland/rev/cc8d417312b7
Part 2 - Remove unused nsFloatCache, nsFloatCacheList, and nsFloatCacheFreeList. r=emilio

Comment 5

[Sandor Molnar[:smolnar]]

https://hg.mozilla.org/mozilla-central/rev/9f2279973623
https://hg.mozilla.org/mozilla-central/rev/cc8d417312b7