Improves performance of allocating unsafe buffers, creating buffers from
an existing ArrayBuffer and creating .slice(...) from existing Buffer by
avoiding deoptimizing change of prototype after Uint8Array allocation
in favor of ES6 native subclassing.
This is done through an internal ES6 class that extends Uint8Array and
is used for allocations, but the regular Buffer function is exposed, so
calling Buffer(...) with or without `new` continues to work as usual
and prototype chains are also preserved.
Performance wins for .slice are +120% (2.2x), and, consequently, for
unsafe allocations up to +95% (1.9x) for small buffers, and for safe
allocations (zero-filled) up to +30% (1.3x).
PR-URL: https://github.com/nodejs/node/pull/7349
Ref: https://github.com/nodejs/node/pull/6893
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Сковорода Никита Андреевич <chalkerx@gmail.com>
Reviewed-By: Trevor Norris <trev.norris@gmail.com>
Ingvar Stepanyan
ac8e1bf609