perf: array forwarding compression, shared add-tree guards, packed shape guards

[proggeramlug]

Lands three reviewed PRs as one squash: #8674, #8675, #8676.

• perf(runtime): compress array forwarding chains #8674 — compress array forwarding chains (clean_arr_ptr multi-hop walk)
• perf(codegen): share numeric guards across dynamic add trees #8675 — share numeric guards across dynamic add trees
• perf(codegen): pack monomorphic method shape guards #8676 — pack monomorphic method shape guards

Why #8672 is not in this batch

All four were authored as one stack on top of #8672, so each PR head carries #8672's commit. Their contents, however, touch disjoint files, so these three are cherry-picked onto main on their own.

#8672 is held deliberately. It defines its own is_bound_native_method_closure_value, which returns true for any bound native-module export with a non-empty module name. main (via #8662) superseded that with is_bound_native_constructor_closure_value, which returns true only for an actual constructor, gated on explicit constructor metadata:

// p8672                                  // main
bound_native_callable_module_and_method   bound_native_callable_is_constructor_value(value)
  .map(|(module, _)| !module.is_empty())

Different truth sets — main's is strictly narrower. Substituting one for the other is a behavioural change at every call site, not a mechanical rename, so it needs the author's judgment rather than mine.

File-size cap

#8674 pushed array/tests.rs from 1998 to 2034 lines, over the 2000-line gate. Split the growth-forwarding group (install_array_growth_forwarding_* plus the three clean_arr_ptr chain-walk tests) into an array/forwarding_tests.rs sibling, following the existing subclass_tests pattern. Pure relocation.

Validation (on the merged result)

• 9 ratchet gates + cargo fmt --all --check: pass
• perry-codegen --lib: 1198 passed, 0 failed (+4)
• perry-runtime --lib (RUST_TEST_THREADS=1): 2652 passed, 0 failed (+1)
• Split proven non-vacuous: all 5 relocated tests verified running under array::forwarding_tests::*, crate total unchanged
• Squashed tree verified byte-identical to the merged tree before push

No version-file changes; three changelog.d/ fragments carried through.

Summary by CodeRabbit

• Performance Improvements

  • Improved array forwarding-chain resolution by compressing validated multi-step chains for faster indexed access.
  • Optimized numeric execution for dynamic additions involving three or more values while preserving existing behavior for non-numeric values.
  • Reduced overhead for packed direct-method checks through consolidated validation.

• Reliability

  • Expanded validation and coverage for array growth, forwarding chains, method guards, and dynamic addition behavior.
  • Preserved safeguards against invalid forwarding targets and cycles.

[coderabbitai]

Caution

Review failed

The pull request is closed.

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 8ee41765-b41c-429c-9983-6daca778b580

📥 Commits

Reviewing files that changed from the base of the PR and between 81ddd46 and 40088b0.

📒 Files selected for processing (12)

• changelog.d/8674-array-forwarding-path-compression.md
• changelog.d/8675-dynamic-add-tree-guard.md
• changelog.d/8676-packed-method-shape-guard.md
• crates/perry-codegen/src/collectors/proven_this_routing_tests.rs
• crates/perry-codegen/src/expr/binary.rs
• crates/perry-codegen/src/expr/dynamic_add_tree_tests.rs
• crates/perry-codegen/src/expr/mod.rs
• crates/perry-codegen/src/lower_call/method_override.rs
• crates/perry-runtime/src/array/forwarding_tests.rs
• crates/perry-runtime/src/array/header.rs
• crates/perry-runtime/src/array/mod.rs
• crates/perry-runtime/src/array/tests.rs

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📝 Walkthrough

Walkthrough

Changes

The PR adds three performance changes: array forwarding-chain compression, shared numeric guards for dynamic addition trees, and packed method-shape validation. Each change includes focused tests or updated assertions and a performance changelog entry.

Array forwarding compression

Layer / File(s)	Summary
Forwarding resolution and validation crates/perry-runtime/src/array/header.rs, crates/perry-runtime/src/array/forwarding_tests.rs, crates/perry-runtime/src/array/tests.rs, crates/perry-runtime/src/array/mod.rs, changelog.d/8674-array-forwarding-path-compression.md	clean_arr_ptr compresses validated multi-hop forwarding chains. Tests cover growth, injected headers, cycles, untracked targets, and chain compression. Existing comments and assertions describe the compressed path.

Dynamic addition tree lowering

Layer / File(s)	Summary
Shared guarded addition lowering crates/perry-codegen/src/expr/binary.rs, crates/perry-codegen/src/expr/dynamic_add_tree_tests.rs, crates/perry-codegen/src/expr/mod.rs, changelog.d/8675-dynamic-add-tree-guard.md	Dynamic + trees with at least three leaves use one shared numeric guard when safe. Tests verify floating-point fast paths, dynamic fallback calls, and direct dispatch for two-leaf trees.

Packed method-shape guards

Layer / File(s)	Summary
Packed header guard validation crates/perry-codegen/src/lower_call/method_override.rs, crates/perry-codegen/src/collectors/proven_this_routing_tests.rs, changelog.d/8676-packed-method-shape-guard.md	Method guards use masked packed header checks and packed class/ShapeId comparisons. Tests verify GC masks, little-endian field layout, and updated inline guard assertions.

Estimated code review effort: 3 (Moderate) | ~25 minutes

Suggested reviewers: thehypnoo, jdalton

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch merge/b8

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