[codex] Hoist invariant numeric array reads in inner loops

[andrewtdiz]

Summary

• hoist invariant numeric arr[i] reads out of eligible inner for (...; j < arr.length; j++) loops
• split the inner-loop CFG so only first entry runs the hoisted guard load; backedges skip the prebody
• add bulk typed-feedback fast-pass accounting for skipped guard calls, plus positive and negative IR tests

Benchmarks

Baseline is ec79e68ff on codex/perry-i32-array-index-lowering; current commit is 5895ca8e7.

• direct 10_nested_loops: 221ms -> 102ms median, sum 26991000000 throughout
• perf stat direct nested: 813.9M -> 422.6M cycles, 3.64B -> 1.84B instructions, 820.6M -> 415.4M branches
• typed-feedback trace: both numeric array get sites still report 9,000,000 observations/passes, 0 failures, 0 fallbacks
• benchmarks/quick.sh: nested_loops 202ms -> 124ms; matrix_multiply stayed in range at 387ms -> 390ms
• benchmarks/compare.sh --quick --runs 3 --warn-only: nested_loops 214ms -> 101ms; JSON at /tmp/perry-compare-invariant-hoist-final.json

Note: local Node.js cannot execute .ts benchmark inputs here, so Node columns/correctness checks were skipped by the harness. benchmarks/baseline.json is stale for this Linux environment, so compare was run with --warn-only and PR deltas use the captured local #5310 baseline.

Validation

• cargo fmt --check
• git diff --check
• cargo test -p perry-codegen --test typed_feedback
• cargo test -p perry-codegen --test typed_shape_descriptors
• PERRY_BIN=target/release/perry python3 tests/test_typed_feedback_runtime_evidence.py
• tests/test_benchmark_output_verifier.sh
• cargo build --release

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[proggeramlug]

Closing as superseded. Since this codex stack was cut, main advanced 52+ commits and independently evolved the same hot codegen/runtime paths. This PR is one link in a 13-deep linear stack that conflicts with diverged, correctness-sensitive codegen and was never reviewed; landing it would mean rebasing the whole stack. It was also flagged as borderline in per-PR review (narrow win and/or unrelated scope creep bundled in).

Specific: bespoke split-CFG (for.prebody/for.cond.backedge) for a narrow single-expression inner-loop shape; high maintenance surface for a benchmark-specific win. A general LICM pass is preferable.