perf(codegen): guard direct Uint32Array RMW

benchmarks/issue-8692/RESULTS.md

@@ -0,0 +1,66 @@
+# Issue #8692 benchmark evidence
+
+Measured 2026-08-24 on an Apple M1 Max running Darwin 25.5.0. The issue
+worktree is based on commit `8224d879a`; the baseline arm uses the same branch
+build with `PERRY_TYPED_ARRAY_RMW=0`. Node is v26.5.1. All Perry inputs were
+compiled with `PERRY_NO_AUTO_OPTIMIZE=1`, the release runtime, `--no-cache`, and
+no PGO.
+
+## Reduced reproduction
+
+The input is `repro.js`: 1,000 `Uint32Array` elements, 2,000 iterations, and
+2,000,000 total dynamic indexed updates. Both arms and Node returned checksum
+`2000`.
+
+Protocol: three warmups followed by 11 alternating enabled/disabled process
+pairs. Times below are medians of the elapsed time measured inside the program.
+RSS is the median of three `/usr/bin/time -l` process runs. Binary sizes are
+exact bytes.
+
+| Build | Median | Paired wins | RSS | Executable |
+| --- | ---: | ---: | ---: | ---: |
+| `PERRY_TYPED_ARRAY_RMW=0` | 80.315 ms | — | 13,500,416 B | 14,734,768 B |
+| guarded direct RMW | 14.760 ms | 11/11 | 13,565,952 B | 14,734,768 B |
+| Node v26.5.1 | 2.620 ms | — | — | — |
+
+The guarded lowering is **5.30x faster** than the disabled baseline. RSS rises
+by 65,536 bytes (0.49%) and executable-size delta is zero. This result does not
+claim Node parity.
+
+The optimized specialized function's `ta.rmw.load`/`ta.rmw.store` blocks contain
+`load i32`, `uitofp`, `fadd`, and `store i32`; they contain none of
+`js_typed_array_index_get_dynamic`, `js_dynamic_string_or_number_add`, or
+`js_typed_array_index_set_dynamic`. The emitted IR retains a full generic
+get/add/set block for precondition failure and a set-only block for post-RHS
+invalidation. The native-representation artifact records
+`TypedArrayRmw.guarded_direct_uint32_add` as `checked_native`, its exact-index and
+bounds guard, the GC-visible receiver reload, and a separate explicit dynamic
+fallback record. A compiler test also records the rejection reason
+`rhs_not_canonical_number`.
+
+## `ecs-benchmark` simple iteration
+
+Source: `ooflorent/ecs-benchmark` at
+`7b53a36606118e8b2a450a2ba4919939c86bbd2e`. Each wrapper imports the repository's
+unchanged `simple_iter` case and calls `setup(1000)`. Iteration counts were
+calibrated per case to keep Perry samples near the upstream harness's roughly
+500 ms target. Node, enabled Perry, and disabled Perry all returned the same
+case name, iteration count, and `semantic: "completed"` record.
+
+After one process warmup, seven enabled/disabled pairs ran simultaneously so
+both arms saw the same shared-host load; child creation order alternated. RSS
+was captured on every measured process. The table reports the median elapsed
+time of each arm. The upstream README documents typical run-to-run variance of
+1–4%, so the increases below are neutral. More decisively, the final Mach-O
+`__text` section is byte-identical between enabled and disabled binaries for all
+four cases: this optimization is not selected by these workloads.
+
+| Case | Iterations | Disabled | Enabled | Delta | Disabled / enabled RSS | Size delta | `__text` SHA-256 |
+| --- | ---: | ---: | ---: | ---: | ---: | ---: | --- |
+| `wolf-ecs/simple_iter` | 250 | 254.540 ms | 259.059 ms | +1.78% | 202,113,024 / 202,244,096 B | 0 B | `b2987e304a8b402d699d80d145a1a1b01391e83591a36e130a4591ffcd9424f6` |
+| `becsy/simple_iter` | 15 | 169.343 ms | 167.251 ms | -1.24% | 46,415,872 / 46,432,256 B | 0 B | `8bdfe53cc561edd2d268b5ec61939ca46bd2140f98303471496b81ab7f7302b1` |
+| `javelin-ecs/simple_iter` | 15 | 284.079 ms | 287.036 ms | +1.04% | 93,716,480 / 93,749,248 B | 0 B | `ec44c45d2a942a29877795c85b68ed218b13c7c0f0073892ad90437485b5cc46` |
+| `piecs/simple_iter` | 1,500 | 736.326 ms | 751.261 ms | +2.03% | 16,171,008 / 16,203,776 B | 0 B | `cd1d310b8ad30a1f90e6dba95ca82dbe4cd8d344188a3868f9744168a7336b8a` |
+
+Exact enabled/disabled executable sizes were respectively 14,949,648;
+16,436,632; 26,191,360; and 14,966,232 bytes for the four rows.

benchmarks/issue-8692/repro.js

@@ -0,0 +1,32 @@
+// Reduced wolf-ecs kernel from https://github.com/PerryTS/perry/issues/8692.
+// Compile with `PERRY_NO_AUTO_OPTIMIZE=1` for the ticket's stable A/B protocol.
+class Query extends Array {
+  archetypes = this;
+}
+
+class Archetype extends Array {
+  entities = this;
+}
+
+const entityCount = 1_000;
+const iterations = 2_000;
+const query = new Query();
+const archetype = new Archetype();
+for (let i = 0; i < entityCount; i++) archetype.push(i);
+query.push(archetype);
+
+const components = new Uint32Array(entityCount);
+
+function system(values) {
+  for (let i = 0, length = query.length; i < length; i++) {
+    const current = query[i];
+    for (let j = 0, length = current.length; j < length; j++) {
+      values[current[j]] += 1;
+    }
+  }
+}
+
+const start = performance.now();
+for (let i = 0; i < iterations; i++) system(components);
+const elapsedMs = performance.now() - start;
+console.log(JSON.stringify({ elapsedMs, checksum: components[0] }));

changelog.d/8692-guarded-uint32-rmw.md

@@ -0,0 +1,7 @@
+### Performance
+
+- Fuse dynamic-index `Uint32Array` numeric read-modify-write expressions behind
+  explicit representation, backing-store, exact-index, and bounds guards. The
+  hot arm keeps the load/add/store in native SSA, while precondition failure and
+  post-RHS invalidation retain full JavaScript evaluation order and conversion
+  semantics through explicit generic fallbacks.

crates/perry-codegen/src/expr/index_set.rs

@@ -754,6 +754,14 @@ pub(crate) fn lower(
             index,
             value,
         } => {
+            if let Some(result) =
+                super::typed_array_rmw::try_lower_guarded_uint32_add(ctx, object, index, value)?
+            {
+                if value_discarded {
+                    return Ok(double_literal(0.0));
+                }
+                return Ok(result);
+            }
             // Issue #611: `globalThis[<key>] = value` writes to the
             // persistent global-this singleton (see the matching IndexGet
             // arm above for context).

crates/perry-codegen/src/expr/mod.rs

@@ -2183,6 +2183,7 @@ mod index_set_guarded;
 mod index_set_typed_array;
 mod instance_misc1;
 mod member_update;
+mod typed_array_rmw;
 pub(crate) use instance_misc1::builtin_parent_reserved_class_id;
 pub(crate) mod class_field_inline_guard;
 pub(crate) mod element_shape_guard;