Local-player analysis: build it only for the passes which use it

[Frotty]

The client-local analysis (LocalPlayerContextAnalyzer) is a whole-program analysis. A Lua build of castle fight or zombie defense made it five times. Two of those five were built for passes which never use it: about a third of the analysis time on both maps.

What changes

• The function splitter runs the copy propagation and the local merger on the compile-time state before splitting it. Both passes ask the analysis only about locals, and a split function has no parameters. The compile-time state of both maps has no locals at all after the flatten (266 and 38,283 elements, 0 locals), so neither pass asked anything. The analysis is now made only when the function has a local, so the output is identical.
• The old-generics cast temporaries (LuaOldGenericsCasts) went through the local merger with a fresh analysis, right before the Lua translation. The merger keeps a client-local value and a synchronized one in separate locals so that the analysis made before it stays true for the passes which use it afterwards (a merged local would hold both values while the analysis still answers for each). This is the last pass and nothing reads an analysis after it, so it now merges without one. Merging only renames locals, so the program does the same, and a client-local local may share its slot with a dead synchronized one.
• isLocalPlayerSource is a lookup in a fixed list of natives. It is now static, so the inliner no longer builds the whole analysis to ask it.
• The merger's barrier now has a comment saying why it is there.

Effect

	castle fight Lua	zombie defense Lua
analyses made	5 → 3	5 → 3
CPU of all analyses per build (two master runs → change)	3.36 / 2.61 s → 1.89 s	1.42 / 1.47 s → 0.95 s
script	identical	3 fewer locals, 344 bytes smaller, same 384,391 instructions (luac)

The zombie defense difference is only merging. Three functions lose one local each; every other function differs only in the numbering of names. Both scripts pass luac -p. The CPU times come from a temporary probe around the constructor (thread CPU time, not committed); a whole build varies more than this from run to run, so no wall time is quoted. Not run in game.

Tests

• oldGenericsCastMergeIgnoresLocality (new, LuaBackendAuditTests): a function with a client-local integer, a synchronized one and an old-generics cast. It checks that the client-local local is reused for a synchronized value. It fails on master, where the client-local value keeps a third local.
• clientLocalNativeValuesAreLocalitySources calls the source list directly and no longer builds an analysis around it.
• Passed (495 tests): LuaBackendAuditTests, OptimizerTests, LocalPlayerContextAnalyzerTests, CompiletimeTests, CompiletimeHashtableTests, CompiletimeNativesTest, LuaTypecastingTests. The full suite is left to CI.

[chatgpt-codex-connector]

Codex Review Summary

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Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-10-11T07:57:07.413536Z	ccfa7c9	Manual request

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[Frotty]

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[chatgpt-codex-connector]

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Reviewed commit: a4b67c740c

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[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. What shall we delve into next?

Reviewed commit: ccfa7c9795

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