Bug 297843 – Use ComplexTextController even for the simple text code path for GTK and WPE ports

• Status: RESOLVED
• Resolution: FIXED
• Component: Text

[Fujii Hironori]

200076@main changed to always use the complex text code path for GTK and WPE ports.
This was done by using `FontCascade::setCodePath(CodePath::Complex)` to choose the complex text code path.
However, this approach involves a unnecessary performance regression.

In most of layout perf test cases, the complex and simple text code paths consume only a tiny portion of time.
In WebCore layout and rendering code, there are some conditions checking the code path like `if (fontCascade.codePath(TextRun(content)) == FontCascade::CodePath::Complex)`.
This yields the difference in performance.
For example, this is a condition making the difference.
https://github.com/WebKit/WebKit/blob/5b46346c7d149fbccefc7835cdce797b999de794/Source/WebCore/layout/formattingContexts/inline/InlineLineBoxBuilder.cpp#L82

Thus, we shouldn't use `FontCascade::setCodePath()` to choose the code path.

In bug#297088, I studied the possibility of implementing Font::applyTransforms with HarfBuzz.
However, HarfBuzz doesn't have an API to implement Font::applyTransforms efficiently.

I'm going to ComplexTextController even for the simple text code path for GTK and WPE ports

the perf test result of bug#297088 comment#12 compares complex, simple and complex-only.

[Fujii Hironori]

Pull request: https://github.com/WebKit/WebKit/pull/49831

[EWS]

Committed 299354@main (23619bf93e9c): <https://commits.webkit.org/299354@main>

Reviewed commits have been landed. Closing PR #49831 and removing active labels.

[Radar WebKit Bug Importer]

<rdar://problem/159499112>