runtime: Garbage collector should not recurse

[johanbrandhorst]

At least within the context of WebAssembly, the conservative GC recursing is causing stack overflows on larger heaps. Ideally it should be possible to make it not recurse.

[aykevl]

This will also be an issue on embedded devices but hasn't been so far.

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The MicroPython GC has avoided recursion by using a fixed-size pointer stack and scanning the complete heap in the worst case, which avoids stack overflow but is not very efficient. I'm not aware of a more efficient algorithm and I doubt one can exist in a simple mark-sweep collector.

[CryZe]

iirc tinygo only uses a single wasm page (of 64 KiB) for the stack. It might make sense to bump that value in addition / as an alternative to rewriting the GC. Rust for example is using 1 MiB of stack on wasm, as is usual on other platforms as well.

[niaow]

The fix #1028 has been merged onto dev and will land in v0.13.