We have been trying to improve sharing in JSC for a while now. We can share bytecode between realms, but this is mostly about reducing parse time rather than space saving - the bytecode has to be "linked" before a realm uses it, which involves making a copy of most of the data structures.
I don't think that full sharing is impossible in the current language. Turning off the link step - or eliminating the need for a full copy - is almost doable, but would have some cost for variable resolution performance in the early iterations of a function. I've been toying with sharing JIT code at the lowest JIT tier, which would have similar trade offs. Something that JSC does have going for it if we had a larger library footprint is that we interpret bytecode for the first 100 or so executions of any function. Even when we have to splat a copy of the bytecode, it still takes less memory than machine code at any level of optimization. So, I'm curious what issues you were specifically concerned about. -Filip > On Jan 13, 2015, at 4:21 AM, Anne van Kesteren <ann...@annevk.nl> wrote: > > A big challenge with self-hosting is memory consumption. A JavaScript > implementation is tied to a realm and therefore each realm will have > its own implementation. Contrast this with a C++ implementation of the > same feature that can be shared across many realms. The C++ > implementation is much more efficient. > > If we want to get further with turning the web platform into a giant > JavaScript library, we need to tackle this somehow. > > Has anyone been thinking about how to do this and what changes it > would require from JavaScript proper? We're now at the point where we > can implement platform objects in terms of JavaScript, but JavaScript > loses out due to lack of efficiency. > > > PS: Alternative explanation available here: > https://annevankesteren.nl/2015/01/javascript-web-platform > > > -- > https://annevankesteren.nl/ > _______________________________________________ > es-discuss mailing list > es-discuss@mozilla.org > https://mail.mozilla.org/listinfo/es-discuss _______________________________________________ es-discuss mailing list es-discuss@mozilla.org https://mail.mozilla.org/listinfo/es-discuss
