[JSC] Immutable Load should look for the CSE target in dominators

[Constellation]

62300f8

[JSC] Immutable Load should look for the CSE target in dominators
https://bugs.webkit.org/show_bug.cgi?id=299504
rdar://161294228

Reviewed by Yijia Huang.

Previous one 300327@main worked for the same basic block's load,
but it didn't work for the load in dominators. This patch updates CSE
rules to make immutable load elimination work with dominators' load.

Like,

    BB#0
    @0: Load(@x, immutable)
    @1: CCall(...) # potentially clobber everything
    Branch ... #1, #2

    BB#1
    @2: CCall(...) # potentially clobber everything
    Jump #3

    BB#2
    @3: CCall(...) # potentially clobber everything
    Jump #3

    BB#3
    @4: Load(@x, immutable)
    ...

Then @4 should be replaced with Identity(@0) as dominator BB#0 is having
immutable load @0 matching to @4.

Tests: Source/JavaScriptCore/b3/testb3_1.cpp
       Source/JavaScriptCore/b3/testb3_8.cpp
* Source/JavaScriptCore/b3/B3EliminateCommonSubexpressions.cpp:
* Source/JavaScriptCore/b3/testb3.h:
* Source/JavaScriptCore/b3/testb3_1.cpp:
(run):
* Source/JavaScriptCore/b3/testb3_8.cpp:
(testLoadImmutableDominated):
(testLoadImmutableNonDominated):

Canonical link: https://commits.webkit.org/300562@main

7552a9a

Misc	iOS, visionOS, tvOS & watchOS	macOS	Linux	Windows	Apple Internal
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 win	✅ 🛠 ios-apple
	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2	✅ 🧪 win-tests	✅ 🛠 mac-apple
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe		✅ 🛠 vision-apple
	✅ 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🛠 wpe-cairo
✅ 🛠 🧪 jsc	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🛠 gtk
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	✅ 🛠 vision-sim	✅ 🧪 mac-wk2-stress	❌ 🧪 api-gtk
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✅ 🛠 🧪 unsafe-merge	✅ 🛠 tv	✅ 🛠 mac-safer-cpp	✅ 🛠 jsc-armv7
	✅ 🛠 tv-sim		✅ 🧪 jsc-armv7-tests
	✅ 🛠 watch
	✅ 🛠 watch-sim

[webkit-early-warning-system]

EWS run on previous version of this PR (hash 8dee5a9)

Misc	iOS, visionOS, tvOS & watchOS	macOS	Linux	Windows	Apple Internal
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 win	✅ 🛠 ios-apple
	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	❌ 🧪 wpe-wk2	✅ 🧪 win-tests	✅ 🛠 mac-apple
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe		✅ 🛠 vision-apple
	✅ 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🛠 wpe-cairo
✅ 🛠 🧪 jsc	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🛠 gtk
✅ 🛠 🧪 jsc-arm64	✅ 🛠 vision	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 gtk-wk2
	✅ 🛠 vision-sim	✅ 🧪 mac-wk2-stress	❌ 🧪 api-gtk
	✅ 🧪 vision-wk2	✅ 🧪 mac-intel-wk2	✅ 🛠 playstation
	✅ 🛠 tv	✅ 🛠 mac-safer-cpp	✅ 🛠 jsc-armv7
	✅ 🛠 tv-sim		❌ 🧪 jsc-armv7-tests
	✅ 🛠 watch
	✅ 🛠 watch-sim

[webkit-early-warning-system]

EWS run on previous version of this PR (hash 9ceb71a)

Misc	iOS, visionOS, tvOS & watchOS	macOS	Linux	Windows	Apple Internal
✅ 🧪 style	🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	🛠 win	✅ 🛠 ios-apple
	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	⏳ 🧪 wpe-wk2	🧪 win-tests	✅ 🛠 mac-apple
✅ 🧪 webkitperl	🧪 ios-wk2	⏳ 🧪 api-mac	⏳ 🧪 api-wpe		✅ 🛠 vision-apple
	⏳ 🧪 ios-wk2-wpt	⏳ 🧪 mac-wk1	🛠 wpe-cairo
🛠 🧪 jsc	🧪 api-ios	✅ 🧪 mac-wk2	✅ 🛠 gtk
✅ 🛠 🧪 jsc-arm64	🛠 vision	🧪 mac-AS-debug-wk2	⏳ 🧪 gtk-wk2
	🛠 vision-sim	✅ 🧪 mac-wk2-stress	⏳ 🧪 api-gtk
	⏳ 🧪 vision-wk2	⏳ 🧪 mac-intel-wk2	🛠 playstation
	🛠 tv	🛠 mac-safer-cpp	✅ 🛠 jsc-armv7
	🛠 tv-sim		⏳ 🧪 jsc-armv7-tests
	🛠 watch
	🛠 watch-sim

[webkit-early-warning-system]

EWS run on current version of this PR (hash 7552a9a)

Misc	iOS, visionOS, tvOS & watchOS	macOS	Linux	Windows	Apple Internal
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 win	✅ 🛠 ios-apple
	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2	✅ 🧪 win-tests	✅ 🛠 mac-apple
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe		✅ 🛠 vision-apple
	✅ 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🛠 wpe-cairo
✅ 🛠 🧪 jsc	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🛠 gtk
✅ 🛠 🧪 jsc-arm64	✅ 🛠 vision	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 gtk-wk2
	✅ 🛠 vision-sim	✅ 🧪 mac-wk2-stress	❌ 🧪 api-gtk
	✅ 🧪 vision-wk2	✅ 🧪 mac-intel-wk2	✅ 🛠 playstation
✅ 🛠 🧪 unsafe-merge	✅ 🛠 tv	✅ 🛠 mac-safer-cpp	✅ 🛠 jsc-armv7
	✅ 🛠 tv-sim		✅ 🧪 jsc-armv7-tests
	✅ 🛠 watch
	✅ 🛠 watch-sim

[hyjorc1]

r=me

[webkit-commit-queue]

Committed 300562@main (62300f8): https://commits.webkit.org/300562@main

Reviewed commits have been landed. Closing PR #51299 and removing active labels.