perf(object): share ordinary property access and slot transactions

[Eric-Song-Nop]

Ordinary own-data assignment previously scanned the prototype chain, materialized complete descriptors and round-tripped through Define. It now locates once, checks writable and updates the existing slot. The same storage owner supports selective Get, value-only Define, presence/enumerability and on-demand prototype traversal. Stacked on #18 (perf/published-vm-execution, fec7519); implements the ordinary-property part of #16.

Storage, ordinary algorithms and observable dispatch have separate responsibilities. Slot positions remain private to a short state borrow; only the needed value/getter/setter is rooted. Set preserves distinct receivers, Proxy completions and rejection identity, Array length conversion order, Arguments, VarRef/AutoInit and cross-runtime checks. Slot replacement retains new references before publication and rolls them back only on pre-publication failure, also fixing Atom ownership after old-edge cleanup failure.

Array and TypedArray regressions are addressed in this version. Genuine Array own slots and directly encoded dense elements share selective value/getter reads; Array misses and non-immediate dense indices retain the existing fallback. Array writes keep their special semantics. TypedArray bounds checking and byte access reuse one owned buffer token, obtained after value conversion for writes; no token is reused across callbacks. The pure bounds calculation is shared with existing state queries.

Performance uses matched Rust 1.94.1 ordinary release builds on a Ryzen 7 7840HS, CPU 2, with identical flags/features. #18's engine is built at documentation-only commit c1dfce3; the final engine is 1cc51bb. Times are fixed-work whole-process wall time, including startup, compilation, setup and teardown. No builds or tests overlap admitted timing.

Ten rotating-order rounds compare #18, the previous #19 engine (9c91663), and the updated engine:

Case	#18 ms	Previous #19 ms	Updated #19 ms	Updated vs #18
prop_read	748.258	648.698	647.334	-13.5%
prop_write	843.843	291.777	291.697	-65.4%
prop_update	870.245	400.179	393.974	-54.7%
array_read	535.363	556.830	438.037	-18.2%
array_length_read	820.210	846.763	583.749	-28.8%
typed_array_read	348.580	372.710	303.577	-12.9%
typed_array_write	311.674	320.219	252.771	-18.9%

The complete 50 microbench + 8 real-program matrix and 38 object diagnostics each use five alternating rounds. The complete tables use the seven ten-round comparisons above for those sensitive cases. No additional over-3% rechecks were needed for the final matrix. Microbench geometric mean time change: -8.6%; real-program change: -12.7%. 8/8 real programs improved. No final matrix or diagnostic case was over 3% slower.

Five alternating rounds of hardware counters support the timing results:

Case	Instructions vs #18	User cycles vs #18
array_length_read	-25.6%	-28.1%
array_read	-8.4%	-17.7%
typed_array_read	-8.8%	-12.6%
typed_array_write	-7.5%	-19.6%
prop_read	-7.7%	-14.4%
prop_write	-61.3%	-65.9%
prop_update	-50.7%	-54.7%

Final-source validation (1cc51bb, Rust 1.88.0):

• Workspace/all-targets with test262-host and the pinned QuickJS oracle: 3,074 passed, 0 failed, 1 existing ignored. Includes the 14 ordinary-property regressions and new dense/slow Array, hole/prototype/receiver, named/Symbol/large-index, conversion resize/detach and shared-buffer coverage.
• QuickJS fixture suites 13/13 and C oracles 19/19; Clippy for default, test262-host and profiling configurations passed. Node/WASM playground passed. Formatting, source layout, architecture scan and all 16 architecture unit tests passed.
• Full Test262: all 102,037 outcomes unchanged (79,982 passes / 80,032 runnable, the same 50 runnable failures). Full TSV and JSONL hashes match frozen receipts after normalizing only the source fingerprint. The strict gate reports fingerprint-related checksum drift; frozen receipts and conformance expectations were not changed. Tested 1cc51bb fingerprint: e4f461c60faf9116313fcbcc6fc062d691f308ad4042e7f98d9a9154d21deea3.
• Documentation head c52d4dc changes only Markdown; Rust sources are byte-identical to tested 1cc51bb. The source-tree fingerprint includes src/engine/object/README.md, so the documentation head has fingerprint 52ff05edb47af54c0a948544156fd7bb7f5509cb84d01096f9c42edbeac53a87; the executable receipts above intentionally identify the immutable tested engine commit.
• The earlier full-plan validation and the independently reproduced perf(vm): reuse publication guarantees in execution #18 Rust 1.94.1 debug native-stack issue are recorded in docs/ordinary-property-plan.md; final correctness checks use the repository's Rust 1.88.0 toolchain.

Reproduce object diagnostics with python3 scripts/benchmark/ordinary_workloads.py --output target/ordinary-diagnostics. Use that manifest or docs/reports/data-structure-fixed-final.json with scripts/benchmark/fixed.py, the plain before/after binaries and --cpu 2 --repeat 5 (10 for rechecks). Build with scripts/benchmark/build.py to record compiler, flags, commit and ELF hashes.

Final receipts, raw stdout/stderr, distributions, counters and verification logs are retained locally under target/property-regfix3-*; these are not public downloads. Before ELF SHA-256: 66b89405a2a283816c5840fef3152a443bd96be2f0723a663198a15f32b0a765. After ELF SHA-256: 4221d5aed8ab9df7f5c8a6992acc6562d6760b2dde9e3376d5f23cf0b4f594a3. The inline-only experiment was reverted. Intermediate dense-read versions exposed a named-property regression and were superseded; their timings are not used in these final tables.

Complete 50 + 8 matrix: median [min–max], ms

Case	#18 ms	This PR ms	Change	Rounds
empty_loop	502.406 [500.764–504.312]	506.895 [501.313–519.338]	+0.9%	5
empty_down_loop	419.087 [415.815–419.857]	421.081 [417.759–422.347]	+0.5%	5
prop_read	748.258 [741.550–778.652]	647.334 [640.247–671.020]	-13.5%	10
prop_write	843.843 [835.460–860.296]	291.697 [288.678–304.183]	-65.4%	10
prop_update	870.245 [863.301–903.509]	393.974 [391.114–397.349]	-54.7%	10
prop_create	408.962 [407.461–411.989]	377.962 [370.945–385.903]	-7.6%	5
prop_clone	340.157 [337.522–341.834]	322.395 [320.503–324.255]	-5.2%	5
prop_delete	407.744 [405.521–408.924]	390.336 [387.917–393.422]	-4.3%	5
array_read	535.363 [526.160–648.324]	438.037 [435.427–484.526]	-18.2%	10
array_write	489.560 [488.540–497.046]	454.425 [454.024–488.040]	-7.2%	5
array_update	499.559 [496.372–508.118]	451.312 [447.844–451.819]	-9.7%	5
array_prop_create	611.453 [606.182–617.473]	579.615 [574.382–595.633]	-5.2%	5
array_slice	407.663 [403.657–417.738]	375.594 [370.895–390.123]	-7.9%	5
array_length_read	820.210 [814.272–855.172]	583.749 [576.050–652.914]	-28.8%	10
array_length_decr	598.094 [595.501–622.540]	558.162 [543.190–568.918]	-6.7%	5
array_push	675.498 [670.628–701.489]	628.085 [615.887–636.804]	-7.0%	5
array_pop	638.804 [632.450–639.975]	567.445 [564.239–578.878]	-11.2%	5
typed_array_read	348.580 [341.478–401.785]	303.577 [298.781–309.167]	-12.9%	10
typed_array_write	311.674 [305.945–393.110]	252.771 [251.125–269.446]	-18.9%	10
arguments_read	356.730 [353.113–365.391]	354.719 [350.656–376.153]	-0.6%	5
arguments_strict_read	333.262 [330.532–338.132]	335.186 [327.758–337.504]	+0.6%	5
global_read	352.271 [349.643–353.321]	351.719 [350.959–354.401]	-0.2%	5
global_write	375.583 [370.340–375.934]	369.073 [366.129–377.750]	-1.7%	5
local_destruct	152.735 [150.857–158.109]	135.726 [134.745–138.372]	-11.1%	5
global_func_call	709.794 [701.918–729.608]	694.555 [690.559–721.977]	-2.1%	5
func_call	672.875 [667.101–682.666]	664.429 [662.273–665.137]	-1.3%	5
func_closure_call	775.522 [770.221–779.774]	779.107 [765.093–804.749]	+0.5%	5
int_arith	570.941 [567.987–577.142]	573.259 [569.963–584.742]	+0.4%	5
float_arith	602.843 [596.944–606.157]	603.462 [594.720–606.697]	+0.1%	5
bigint64_arith	460.271 [454.327–470.170]	470.916 [458.815–493.474]	+2.3%	5
map_set_string	38.699 [37.831–40.006]	36.855 [36.730–37.591]	-4.8%	5
map_set_int	50.960 [50.632–51.935]	49.252 [48.650–49.638]	-3.4%	5
map_delete	60.183 [59.715–60.972]	57.882 [57.493–60.089]	-3.8%	5
weak_map_set	360.713 [354.055–372.849]	334.050 [330.305–420.837]	-7.4%	5
array_for	457.622 [450.861–471.152]	401.152 [394.642–435.158]	-12.3%	5
array_for_in	843.188 [826.314–866.890]	790.905 [787.203–801.680]	-6.2%	5
array_for_of	654.967 [650.707–665.062]	547.880 [544.744–559.739]	-16.3%	5
math_min	790.743 [786.076–816.525]	748.583 [744.555–766.092]	-5.3%	5
regexp_ascii	420.005 [417.600–429.590]	411.431 [410.357–422.147]	-2.0%	5
regexp_utf16	428.251 [422.706–431.097]	421.987 [416.174–426.184]	-1.5%	5
regexp_replace	801.649 [788.485–862.689]	789.754 [777.905–813.060]	-1.5%	5
string_length	594.695 [591.361–603.856]	605.354 [596.827–627.788]	+1.8%	5
string_build1	295.764 [287.950–341.877]	290.007 [286.942–293.717]	-1.9%	5
string_build3	298.293 [296.623–306.697]	298.619 [295.937–308.984]	+0.1%	5
string_build_large1	315.879 [313.288–330.326]	313.945 [311.479–319.679]	-0.6%	5
string_build_large2	317.897 [313.194–325.466]	315.924 [313.683–362.060]	-0.6%	5
int_to_string	281.037 [277.610–289.134]	282.269 [280.617–283.262]	+0.4%	5
float_to_string	1537.538 [1535.385–1556.252]	1564.000 [1561.732–1581.290]	+1.7%	5
string_to_int	162.293 [158.519–163.350]	160.058 [155.575–161.067]	-1.4%	5
string_to_float	139.732 [136.064–145.904]	136.180 [134.180–137.562]	-2.5%	5
v8-richards	111.232 [110.159–113.185]	75.598 [75.164–76.554]	-32.0%	5
v8-deltablue	168.644 [166.223–170.333]	134.763 [133.355–138.549]	-20.1%	5
v8-crypto	2298.372 [2273.651–2341.691]	2042.633 [2029.883–2062.143]	-11.1%	5
v8-raytrace	1012.814 [1002.123–1013.397]	928.652 [922.374–936.758]	-8.3%	5
v8-earley-boyer	2659.756 [2646.421–2674.981]	2551.708 [2543.191–2565.736]	-4.1%	5
v8-regexp	5628.493 [5587.969–5648.373]	5484.431 [5458.627–5512.847]	-2.6%	5
v8-splay	3406.722 [3368.120–3441.305]	3136.662 [3121.869–3150.973]	-7.9%	5
v8-navier-stokes	1908.416 [1893.673–2488.604]	1691.208 [1678.671–1743.124]	-11.4%	5

Complete 38 object diagnostics: median [min–max], ms

Case	#18 ms	This PR ms	Change	Rounds
own-write-depth-0	149.808 [148.661–153.591]	65.600 [65.074–67.650]	-56.2%	5
own-setup-depth-0	5.449 [5.227–5.656]	5.181 [4.639–5.328]	-4.9%	5
own-write-depth-1	155.796 [154.201–160.092]	66.275 [65.784–67.537]	-57.5%	5
own-setup-depth-1	5.569 [4.922–5.704]	5.362 [4.988–5.738]	-3.7%	5
own-write-depth-8	185.814 [182.730–193.822]	66.851 [65.133–68.530]	-64.0%	5
own-setup-depth-8	4.623 [4.535–5.453]	4.674 [4.539–5.241]	+1.1%	5
own-write-depth-64	429.666 [427.662–431.198]	65.454 [65.143–67.628]	-84.8%	5
own-setup-depth-64	5.520 [5.138–5.913]	5.507 [5.462–5.781]	-0.2%	5
own-write-depth-256	1220.011 [1217.383–1303.761]	66.902 [65.828–68.246]	-94.5%	5
own-setup-depth-256	5.754 [5.558–5.823]	5.707 [5.617–5.809]	-0.8%	5
write-width-4-shape	82.197 [79.299–83.791]	35.124 [35.046–36.749]	-57.3%	5
write-width-4-dictionary	80.728 [79.631–81.110]	35.463 [35.053–35.711]	-56.1%	5
write-width-32-shape	80.532 [79.498–82.669]	35.921 [35.190–37.597]	-55.4%	5
write-width-32-dictionary	81.432 [80.070–82.981]	35.669 [34.880–36.197]	-56.2%	5
write-width-256-shape	80.606 [79.490–85.470]	36.524 [35.809–39.700]	-54.7%	5
write-width-256-dictionary	80.078 [79.901–83.130]	35.571 [35.448–38.525]	-55.6%	5
write-width-2048-shape	84.020 [82.341–86.864]	38.364 [37.217–38.920]	-54.3%	5
write-width-2048-dictionary	84.199 [82.534–89.814]	38.385 [37.956–40.687]	-54.4%	5
write-value-int	107.140 [105.531–109.002]	52.914 [52.186–53.754]	-50.6%	5
write-value-float	107.857 [106.285–109.624]	55.174 [52.288–55.758]	-48.8%	5
write-value-string	105.560 [103.553–106.403]	54.240 [52.605–55.798]	-48.6%	5
write-value-symbol	123.178 [121.304–123.677]	58.867 [58.203–60.965]	-52.2%	5
write-value-object	119.666 [118.064–121.858]	56.759 [56.094–57.680]	-52.6%	5
get-data	45.457 [44.602–47.775]	42.727 [41.478–43.590]	-6.0%	5
get-inherited	51.874 [51.179–53.584]	43.294 [42.522–45.402]	-16.5%	5
get-accessor	77.480 [76.982–80.234]	73.245 [73.039–73.440]	-5.5%	5
set-accessor	89.439 [87.619–90.478]	79.640 [78.802–82.770]	-11.0%	5
set-receiver	166.828 [162.737–172.400]	116.598 [114.506–119.489]	-30.1%	5
define-value	414.284 [412.407–415.518]	306.300 [302.843–332.546]	-26.1%	5
has-own	107.882 [105.826–112.852]	104.012 [102.345–105.587]	-3.6%	5
enumerable	113.499 [112.866–113.675]	95.247 [94.209–97.456]	-16.1%	5
proxy-set	42.181 [41.406–44.338]	33.059 [32.499–33.633]	-21.6%	5
missing-get	59.986 [59.021–61.671]	48.347 [46.718–58.165]	-19.4%	5
write-same-value-int	82.576 [81.929–85.610]	37.879 [36.856–38.190]	-54.1%	5
write-same-value-float	82.496 [81.971–91.411]	37.695 [36.235–38.690]	-54.3%	5
write-same-value-string	81.917 [80.424–82.424]	37.581 [36.365–38.291]	-54.1%	5
write-same-value-symbol	99.811 [97.632–103.024]	43.623 [42.295–44.139]	-56.3%	5
write-same-value-object	96.848 [94.583–98.192]	42.214 [42.057–44.598]	-56.4%	5