[ammarahm-ed]

A JS array passed as int[] or double[] was read one element at a time: a handle, a conversion call and a status check per element. The elements are now copied into a double buffer in one pass and converted from there.

• Node-API. New js_get_array_doubles in each engine's jsr.cpp. On V8 it walks the packed backing store with v8::Array::Iterate; the other engines loop over napi_get_element.
• Direct runtime. New Array::copyNumbers on each engine backend, the same split.

If an element is not a number, or a dictionary-mode array skipped a hole, the bulk read reports failure and the existing per-element path runs, so conversion results do not change. For int[] the buffer is also range-checked: a value outside the int range falls back to the per-element path, which applies the engine's own wrapping, instead of a cast that is undefined for out-of-range doubles.

Results

V8 release build on a Sony SO-01M (Android 11, arm64), AOT-compiled with cmd package compile -m speed. One warm-up launch is discarded, then 5 launches; values are the median ns per call.

Case	Node-API before	after	Δ	Direct before	after	Δ
Pass a 16 Int Array	4,668	2,918	-37%	5,262	3,532	-33%
Pass a 16 Double Array	5,012	3,368	-33%	5,931	4,059	-32%
Pass an Int Array	3,264	2,836	-13%	4,135	3,452	-17%
Pass a Double Array	3,134	2,858	-9%	3,970	3,477	-12%
Pass a String Array	5,661	5,401	-5%	6,846	6,693	-2%
Pass a Boolean Array	2,980	3,084	+3%	3,812	3,688	-3%

The 3-element rows and the 16-element rows are the same code path, so the gain grows with the array length. String and boolean arrays do not use this path and are unchanged.

All cases

Case	Node-API before	after	Δ	Direct before	after	Δ
Void Method on instance	662	648	-2%	596	589	-1%
Field on instance	804	855	+6%	835	852	+2%
Int Field on instance	377	370	-2%	386	380	-1%
Get Static Field	813	901	+11%	850	832	-2%
Void Static Method	292	298	+2%	313	311	-1%
multiply(a, b)	486	479	-1%	520	534	+3%
Pass and return string	1,218	1,245	+2%	1,202	1,142	-5%
Return a String	836	804	-4%	760	766	+1%
Return an Int	315	326	+3%	315	320	+2%
Pass a String	700	699	-0%	687	693	+1%
Return a Boolean	313	317	+1%	313	311	-1%
Return a Double	399	391	-2%	395	379	-4%
Pass an Int	415	376	-9%	420	447	+6%
Pass a Double	397	386	-3%	425	436	+3%
Pass a Boolean	480	478	-0%	424	439	+3%
Return an Int Array	27,918	27,821	-0%	20,068	20,322	+1%
Pass an Int Array	3,264	2,836	-13%	4,135	3,452	-17%
Return a String Array	29,130	29,956	+3%	21,210	21,494	+1%
Pass a String Array	5,661	5,401	-5%	6,846	6,693	-2%
Return a Double Array	27,120	27,452	+1%	20,490	21,228	+4%
Pass a Double Array	3,134	2,858	-9%	3,970	3,477	-12%
Return a Boolean Array	26,139	26,138	-0%	19,611	20,402	+4%
Pass a Boolean Array	2,980	3,084	+3%	3,812	3,688	-3%
Int Array[0] read	361	352	-2%	240	240	+0%
String Array[0] read	784	792	+1%	666	670	+1%
Double Array[0] read	426	476	+12%	342	346	+1%
Boolean Array[0] read	350	353	+1%	234	235	+0%
Int Array[0] write	511	462	-10%	364	362	-0%
String Array[0] write	1,220	1,122	-8%	1,072	1,060	-1%
Double Array[0] write	546	465	-15%	373	369	-1%
Boolean Array[0] write	513	475	-7%	367	363	-1%
Return a Date Object	13,411	14,326	+7%	13,814	13,925	+1%
Pass a Date Object	3,688	3,926	+6%	3,749	3,576	-5%
Invoke void callback	7,358	7,692	+5%	6,899	6,890	-0%
Instance add(a, b)	832	812	-2%	796	798	+0%
Pass and return non-ASCII string	1,252	1,253	+0%	1,190	1,125	-5%
Pass and return 1KB string	5,040	5,027	-0%	5,114	5,096	-0%
Return a Char	343	352	+3%	350	350	+0%
Return this	1,261	1,392	+10%	1,354	1,315	-3%
Return a new object	12,744	13,189	+3%	12,359	12,439	+1%
Call a method on a new object	19,368	19,556	+1%	19,891	19,832	-0%
Pass a 16 Int Array	4,668	2,918	-37%	5,262	3,532	-33%
Pass a 16 Double Array	5,012	3,368	-33%	5,931	4,059	-32%
Invoke int callback	10,765	13,802	+28%	10,634	9,772	-8%
Invoke string callback	8,908	9,389	+5%	11,360	8,767	-23%
Native heap after run (MB)	106 MB	106 MB	+0%	97 MB	97 MB	+0%

Only V8 was built and run. The Hermes, JSC, QuickJS-NG and PrimJS readers in this change have not been built or run.

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