Parents: #475, #479 Related: #461, #493, #602
Problem
IntlDateTimeFormatData.Field is already a closed native enum whose string() method returns one of the ECMA-402 fixed field/style names. Intl.DateTimeFormat.prototype.resolvedOptions() currently turns those enum values back into byte slices and allocates a managed StringCell for every non-empty component and style on every call.
The existing representative_intl_date_time_format_construct_components row performs 3,200 constructor + resolvedOptions() operations per 100 jobs. On current main (e9d641d3), its exact invocation delta after warmup is 140,817 managed-cell allocations and 265,626 backing allocations with checksum 914,759,620. This issue will isolate the enum projections inside that unchanged workload.
Scope
- Add an exact
Valueprojection for every non-emptyIntlDateTimeFormatData.Fieldcase using immutable static StringCells. - Use that projection for resolved component names and
dateStyle/timeStyleonly; locale, calendar, numbering-system, time-zone, and other dynamically owned strings remain on their existing path. - Preserve ECMA-402 property presence and insertion order, component/style exclusivity, exact bytes, forced-GC lifetime, and all constructor option-observation behavior.
- Measure exact-parent cell/backing allocation deltas and order-balanced paired timing on default, component, style, and locale constructor rows.
No-workaround rules
- Do not cache or reuse the observable resolved-options object, skip fields the benchmark does not read, recognize benchmark source/name, intern attacker-controlled strings globally, or weaken GC ownership.
- Do not touch Promise, microtask, Worker, Thread lifecycle, stacks, queues, or jobs code.
Acceptance
- Every emitted Field value is the exact unmanaged static cell for its spec spelling;
.noneremains absent. - The existing workload keeps identical work, option objects, property order, and checksum while exact cell/backing allocations fall by the predicted number of emitted enum strings.
- Exact test262 DateTimeFormat coverage has zero flips/regressions.
- Focused normal/TSan, bounded/moving GC, and full sharded unit gates pass.
- Paired timing and allocation evidence are recorded even if the wall result is neutral; no broad performance claim is made without evidence.
Security boundary
Option objects and call frequency are attacker-controlled. The optimization must only project validated closed enum state and must not introduce mutable global caches, lifetime ambiguity, or any fallback from dynamic string ownership.