Optimize {__proto__:null} object literal creation #1118
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Speeds up the common pattern of creating prototype-less objects by 40%:
TEST N TIME (ns) REF (ns) SCORE (%)
object_null 20000 124.50
TEST N TIME (ns) REF (ns) SCORE (%)
object_null 50000 74.30
It's so much faster the benchmarker decides to run it 50,000 times
instead of merely 20,000 times. Win.
bnoordhuis
commented
Jun 30, 2025
| @@ -16748,6 +16749,11 @@ static JSValue JS_CallInternal(JSContext *caller_ctx, JSValueConst func_obj, | |||
| if (unlikely(JS_IsException(sp[-1]))) | |||
| goto exception; | |||
| break; | |||
| case OP_SPECIAL_OBJECT_NULL_PROTO: | |||
| *sp++ = JS_NewObjectProtoClass(ctx, JS_NULL, JS_CLASS_OBJECT); | |||
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I tried caching the shape for prototype-less objects on the JSContext (like it's done for ctx->array_shape) and calling JS_NewObjectFromShape(ctx, js_dup_shape(ctx->null_proto_shape), JS_CLASS_OBJECT) but it has no measurable impact on the micro-benchmark.
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Speeds up the common pattern of creating prototype-less objects by 40%:
It's so much faster the benchmarker decides to run it 50,000 times instead of merely 20,000 times. Win.