Unmanaged execution-context records

Date: 2026-08-26 Area: runtime, bytecode

TGocciaExecutionContext stays an unmanaged record. Source paths are interned to stable UnicodeString nodes and stored as pointers, so Push/Pop copy only pointers instead of FPC_COPY of a managed string on every call.

Richards host samples of the production bytecode loader were dominated by SetupNewFrame / TeardownCurrentFrame paying FPC_COPY because the context record still carried SourcePath: string. After this change, interleaved AWFY on darwin/aarch64 moved Richards about 18% versus the previous stack tip, and the eight-guard geomean goccia_over_qjs from about 15.0 to 14.1. The reader API is unchanged: SourcePath remains a string property.

This is not guest-string interning. ADR 0013 rejected content-keyed caches of TGocciaStringLiteralValue on RuntimeCopy. The intern here is a native, thread-local list of diagnostic file paths so the execution-context record can stay unmanaged. It does not sit on RuntimeCopy and does not intern guest strings.

Making the diagnostic TGocciaCallFrame unmanaged the same way was measured on the same host and rejected: Richards did not move (median ratio 0.9998). bytecode-vm.md.