JuliaLang / julia / 1554

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Commit Message

inference: avoid allocating alias groups when no aliasing is possible (#61943)

`compute_alias_groups` unconditionally allocated a `Vector{Int}` on
every
call, even though it is reached from `unionsplitcost` on the inference
hot
path (method matching, `typesubtract`, apply, and tfuncs). In the common
case no arguments alias, so the allocated vector was just the identity
grouping and carried no information.

Add a cheap, non-allocating `any_alias_candidate` pre-check and return
`nothing` when no aliasing is possible. Both callers already treat a
`nothing` grouping identically to the identity grouping, so behavior is
unchanged while the allocation disappears on the no-alias paths.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Coverage Stats

18 of 18 new or added lines in 1 file covered. (100.0%)

2296 existing lines in 68 files now uncovered.

65139 of 84594 relevant lines covered (77.0%)

16032055.04 hits per line