Merge adjacent implicit binding partitions

[Keno]

After:

julia> convert(Core.Binding, GlobalRef(Base, :Intrinsics))
Binding Base.Intrinsics
   617:∞ - implicit `using` resolved to constant Core.Intrinsics
   0:616 - undefined binding - guard entry

julia> convert(Core.Binding, GlobalRef(Base, :Math))
Binding Base.Math
   22128:∞ - constant binding to Base.Math
   0:22127 - backdated constant binding to Base.Math

There is a bit of trickiness here. In particular, the question is, "when do we check" whether the partition next to the one we currently looked at happens to have the same implicit resolution as our current one. The most obvious answer is that we should do it on access, but in practice that would require essentially scanning back and considering every possible world age state at every lookup. This is undesirable - the lookup is not crazy expensive, but it can add up and most world ages we never touch, so it is also wasteful.

This instead implements a different approach where we only perform the resolution for world ages that somebody actually asked about, but can then subsequently merge partitions if we do find that they are identical. The logic for that is a bit involved, since we need to be careful to keep the datastructure valid at every point, but does address the issue.

Fixes #57923

[Copilot]

Pull Request Overview

This PR refactors the mechanism for merging adjacent implicit binding partitions to improve lookup efficiency and reduce unnecessary work. Key changes include refactoring the merging logic in module.c, converting the min_world field to atomic in julia.h, and updating binding partition field metadata in jltypes.c.

Reviewed Changes

Copilot reviewed 3 out of 4 changed files in this pull request and generated no comments.

File	Description
src/module.c	Refactored atomic operations and merging logic for binding partitions.
src/julia.h	Changed min_world to an atomic type to support concurrent access.
src/jltypes.c	Updated bitmask configuration for atomic fields and added constant field settings.

Files not reviewed (1)

• test/rebinding.jl: Language not supported

Comments suppressed due to low confidence (2)

src/jltypes.c:3269

• [nitpick] The comment describing the atomic fields is inconsistent with the previous version. Please update the comment to accurately reflect that fields 1, 2, 3, and 4 are now set as atomic.

const static uint32_t binding_partition_atomicfields[] = { 0b01111 }; // Set fields 1, 2, 3, 4 as atomic

src/module.c:157

• [nitpick] Consider adding tests that validate the behavior of this CAS loop under concurrent modifications to ensure the retry logic for merging partitions functions correctly.

if (!jl_atomic_cmpswap(&prev->next, &next, nextnext)) {