Re: [v8-users] ArrayBuffer fast access
> I couldn't find any fast access defined in the JIT compiler There are fast paths for typed arrays inside V8, they are just not called typed arrays :-) Look for "external arrays" instead. For them V8 has both specialized IC stubs (e.g. load stub: https://github.com/v8/v8/blob/master/src/ia32/stub-cache-ia32.cc#L3508 ) and support in optimizing compiler pipeline (see IR instructions: LoadExternalArrayPointer, LoadKeyedSpecializedArrayElement, StoreKeyedSpecializedArrayElement). I always use typed arrays when they are available (this communicates my intent both to the JIT compiler and to a person reading my code). -- Vyacheslav Egorov On Sat, Jun 16, 2012 at 5:44 PM, Pablo Sole wrote: > Hello there, > > I'm embedding v8 into a binary instrumentation framework and I'm trying > to use an ArrayBuffer/TypedBuffer for fast memory operations (like > Tamarin/ActionScript does for the Memory object operations), but I > couldn't find any fast access defined in the JIT compiler, so I suppose > that a read/write to a TypedBuffer goes all the way of an object and > property resolution. Although, for this case it could just be a range > check and a memory load/store operation. > > So, would it be faster to use a regular array of SMIs (SMIs in the > indexes and in the values) without holes faster than an ArrayBuffer? Is > there any plan to provide a fast path for this case? > > Thanks, > > pablo. > > -- > v8-users mailing list > v8-users@googlegroups.com > http://groups.google.com/group/v8-users -- v8-users mailing list v8-users@googlegroups.com http://groups.google.com/group/v8-users
Re: [v8-users] ArrayBuffer fast access
Accessing TypedArrays is at least as fast as accessing regular JSArrays, since they never contain holes and the optimizing compiler knows what types to expect from their elements. Basically the recently introduced special handling of SMI arrays without holes is an attempt to get them closer to TypedArray performance. Note that TypedArrays (a.k.a. "external arrays") are not defined in V8 itself. They are implemented by the embedder, e.g. the developer shell "d8" or the WebKit V8 bindings. Look at these two examples for how to do that. On Sat, Jun 16, 2012 at 5:44 PM, Pablo Sole wrote: > Hello there, > > I'm embedding v8 into a binary instrumentation framework and I'm trying > to use an ArrayBuffer/TypedBuffer for fast memory operations (like > Tamarin/ActionScript does for the Memory object operations), but I > couldn't find any fast access defined in the JIT compiler, so I suppose > that a read/write to a TypedBuffer goes all the way of an object and > property resolution. Although, for this case it could just be a range > check and a memory load/store operation. > > So, would it be faster to use a regular array of SMIs (SMIs in the > indexes and in the values) without holes faster than an ArrayBuffer? Is > there any plan to provide a fast path for this case? > > Thanks, > > pablo. > > -- v8-users mailing list v8-users@googlegroups.com http://groups.google.com/group/v8-users
[v8-users] ArrayBuffer fast access
Hello there, I'm embedding v8 into a binary instrumentation framework and I'm trying to use an ArrayBuffer/TypedBuffer for fast memory operations (like Tamarin/ActionScript does for the Memory object operations), but I couldn't find any fast access defined in the JIT compiler, so I suppose that a read/write to a TypedBuffer goes all the way of an object and property resolution. Although, for this case it could just be a range check and a memory load/store operation. So, would it be faster to use a regular array of SMIs (SMIs in the indexes and in the values) without holes faster than an ArrayBuffer? Is there any plan to provide a fast path for this case? Thanks, pablo. -- v8-users mailing list v8-users@googlegroups.com http://groups.google.com/group/v8-users
