julia

03f7bcd5 - fix false-positive `multiloc` in AllocOpt escape analysis (#61131)

fix false-positive `multiloc` in AllocOpt escape analysis (#61131) discovered via automated Claude audit for typos and other minor / obvious bugs. I manually reviewed each result if anybody is getting annoyed at the amount of AI code I am pushing please let me know! it seems to be doing a good job and I am doing my best to clean it all up + be camera ready, but I just want to double check. example benchmark: ``` julia> using BenchmarkTools julia> mutable struct AnyBox val::Any end julia> function preserve_any(x) b = AnyBox(x) GC.@preserve b begin return b.val end end julia> function loop(n) s = "v" for _ in 1:n s = preserve_any(s)::String end s end julia> @benchmark loop(10) ### master BenchmarkTools.Trial: 10000 samples with 996 evaluations per sample. Range (min … max): 25.979 ns … 1.413 μs ┊ GC (min … max): 0.00% … 96.22% Time (median): 28.908 ns ┊ GC (median): 0.00% Time (mean ± σ): 31.487 ns ± 24.859 ns ┊ GC (mean ± σ): 6.74% ± 9.68% ▃█▅▃ ▁ █████▇▇▆▆▅▅▅▅▁▄▃▄▃▁▃▁▁▅▁▁▁▃▄▃▁▁▃▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▄▅▆▇▆▆▆ █ 26 ns Histogram: log(frequency) by time 134 ns < Memory estimate: 144 bytes, allocs estimate: 9. ### PR BenchmarkTools.Trial: 10000 samples with 1000 evaluations per sample. Range (min … max): 2.084 ns … 45.042 ns ┊ GC (min … max): 0.00% … 0.00% Time (median): 2.167 ns ┊ GC (median): 0.00% Time (mean ± σ): 2.204 ns ± 0.560 ns ┊ GC (mean ± σ): 0.00% ± 0.00% ▂ █ ▆ ▅ ▂ ▂ ▁ ▃▁▁▁▁▁▁█▁▁▁▁▁▁█▁▁▁▁▁▁█▁▁▁▁▁▁█▁▁▁▁▁▁▁█▁▁▁▁▁▁█▁▁▁▁▁▁█▁▁▁▁▁▁▆ █ 2.08 ns Histogram: log(frequency) by time 2.42 ns < Memory estimate: 0 bytes, allocs estimate: 0. ``` this is technically two different bugfixes in one. claude found the `?` precedence one first, then found the other while attempting to write a test for it. description: Fix a false-positive `multiloc` flag in `addMemOp` that prevented AllocOptPass from stack-promoting any allocation with GC-pointer fields. The `hasobjref` flag is initialized to `false` in the Field constructor but only set to `true` after the `multiloc` check, so the first access to a new objref field always triggered `multiloc = true`. Guard the check with `!field.second.accesses.empty()` so it only fires when there is a prior access with a different ref/bits kind. This caused AllocOptPass to bail with "unusual object reference" on every non-escaping mutable struct with a reference-typed field (Any, String, Vector, etc.), blocking both `splitOnStack` and `moveToStack`. Also fix an operator precedence bug in the atomicrmw/cmpxchg escape check: `!=`bound tighter than `?:` https://github.com/JuliaLang/julia/blob/74b7adc233b6a23a8f38eedd3830ee99cc6ac161/src/llvm-alloc-helpers.cpp#L321 --------- Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>