Wasm Support

[John_McCall]

@kateinoigakukun

Upstream unconditional absolute addressing

Sounds good. Just for data-to-code references, right?

@kateinoigakukun

Evolve the toolchain for PIC support and linker for fitting 64bit address in 32bit field by the time when wasm64 and dynamic linking ABI will become stable

Please do push the dynamic-linker people to add an easy image-base lookup function.

@kateinoigakukun

Adopt 64bit and PIC based on the evolution

Sounds good.

@kateinoigakukun

We can think like the following layout which embeds discriminator bits, isSmall and isPIC, in a 32bit to utilize absolute pointer and relative pointer.

Yeah, I like this quite a bit.