B3::ReduceStrength is overly conservative at applying specializeSelect

[kmiller68]

3e74b00

B3::ReduceStrength is overly conservative at applying specializeSelect
https://bugs.webkit.org/show_bug.cgi?id=270577
rdar://124146878

Reviewed by Justin Michaud.

Right now it only applies if both outputs from a select are constant. The comment
and testing indicates this is profitable as long as one of the two outputs is a constant.
This looks like a 1.7% speedup on JS3.

* Source/JavaScriptCore/b3/B3ReduceStrength.cpp:

Canonical link: https://commits.webkit.org/275765@main

e6365b5

Misc	iOS, tvOS & watchOS	macOS	Linux	Windows
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	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe
	💥 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🛠 wpe-skia
✅ 🛠 🧪 jsc	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🛠 gtk
✅ 🛠 🧪 jsc-arm64	✅ 🛠 tv	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 gtk-wk2
	✅ 🛠 tv-sim		❌ 🧪 api-gtk
	✅ 🛠 watch		✅ 🛠 jsc-armv7
✅ 🛠 🧪 unsafe-merge	✅ 🛠 watch-sim		✅ 🧪 jsc-armv7-tests

[webkit-early-warning-system]

EWS run on current version of this PR (hash e6365b5)

Misc	iOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 wincairo
	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe
	💥 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🛠 wpe-skia
✅ 🛠 🧪 jsc	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🛠 gtk
✅ 🛠 🧪 jsc-arm64	✅ 🛠 tv	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 gtk-wk2
	✅ 🛠 tv-sim		❌ 🧪 api-gtk
	✅ 🛠 watch		✅ 🛠 jsc-armv7
✅ 🛠 🧪 unsafe-merge	✅ 🛠 watch-sim		✅ 🧪 jsc-armv7-tests

[justinmichaud]

r=me

[webkit-commit-queue]

Committed 275765@main (3e74b00): https://commits.webkit.org/275765@main

Reviewed commits have been landed. Closing PR #25539 and removing active labels.