Can modern garbage collectors deal with almost full heaps? There is an urban legend that GC only shows good performance with 50% of memory free, which is certainly unacceptable for microcontrollers. Also, most garbage collectors require boxing which prevents tight packing of heap data. Are all these problems already solved somewhere? Jitter is the least important issue as there are a lot of works on realtime collectors.
Unfortunately I've no idea how the various GCs deal with the trade-offs; my point is that (memory bandwidth / memory size) in these embedded things is high enough that garbage-collection is fast, contrary to popular wisdom. I was looking at OCAPIC for an example, which has a very simple stop and copy gc which takes 1.5ms to collect. The trade-offs would have some 2× impact on some metric, but not change the feasibility of the thing.
My point is that 2x slowdown is critical for many systems - embedded, gamedev, HPC, systems software. Controlled measurement of slow-down and heap slack caused by GC is beyond capabilities of most embedded devs. Academia provided us with some experimental results saying that in half-empty heaps GC is lightning fast, but there's no (recent) data for 90% full heaps and for very large heaps.
I mean high-performance implementations. Techniques to (statically) compile prototypes into efficient code were developed, but they are largely irrelevant to Javascript. High-performance modern implementations of JS rely on tracing JIT.
It is not necessary. With software replacement for MMU possible (see Singularity OS), hardly any hardware safety support is a requirement nowadays. TAL is the way to go - AFAIK it is possible to make plain x86 assembly dependently typable by attaching proof witnesses to EXE.
Well, BitC is not too popular either. Another interesting experiment is Sing#/Singularity, which is a successful attempt to get IO performance of FreeBSD despite designing whole OS in modified dependently-typed C# with usual JIT and garbage collection. The question whether GC is applicable in memory-constrained environments is still open - I couldn't find a single research in this direction.
