ast: build the lowering context on first use - #63067
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`jl_init_flisp` loaded the flisp system image at every start. A program that never lowers an expression never needs it, and `jl_ast_ctx_enter` already builds a context when its free list is empty, so the eager call becomes the mutex initialization alone. `julia --startup-file=no -e ''`: 76.4 → 66.2 ms, minimum of 15 pinned runs. A REPL or a script lowers immediately and is unaffected; a compiled program gains the same 7 ms. Assisted-by: Claude Code (Opus 5)
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This was referenced Sep 8, 2026
jl_init_flisp builds the lowering context at every start, and a compiled program never lowers
#63066
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jl_init_flisploads the flisp system image at every start. A program that never lowers an expression never needs it, andjl_ast_ctx_enteralready builds a context when its free list is empty. The eager build becomes the mutex initialization alone, and the static context goes away.julia --startup-file=no -e '': 76.4 → 66.2 ms, minimum of 15 pinned runs (median 77.2 → 66.9). A script or a REPL lowers immediately and gains nothing; a compiled program gains the same 7 ms.The context is built inside
JL_SIGATOMIC_BEGIN, as the free-list path already did.syntax,metaandcorepass.Fixes #63066. Part of #63065.
Disclosure: developed with Claude Code (Opus 5) under my direction. It wrote the code and this text; the measurements were run on my machine. I reviewed the changes. The commits carry an
Assisted-bytrailer.