WASM is _designed_ to be easily jitted, without the expensive machinery we had to put in place to do this for x86, so the whole point is not require a new architecture.
Because of this I find WASM to be the best direction yet for a "universal ISA" as it's very feasible to translate to most strange new radical architecture (like EDGE, Prodigy, etc). (Introducing a new ISA is almost impossible due to the cost of porting the world. RISC-V might be the last to succeed).
"WASM is _designed_ to be easily jitted, without the expensive machinery we had to put in place to do this for x86"
I'm not sure this is actually true, given that the original intent was for WASM to be easy to compile using existing JS infrastructure, not in general. So given that, it would make sense to carry over JS fp->int semantics into WASM. WASM is in effect a successor to asm.js.
It's certainly also not too hard to compile/jit for new architectures, but that was not the initial intent or what guided the early/mid-stage design process.
If you examine the current WASM spec, it doesn't appear to specify semantics at all for trunc. I would expect it inherits the exact behavior from JS.
True, but wasn't my point with "expensive machinery". By that I was referring to
* discovering which instructions are executed (tracking control flow),
* mapping x86 code addresses to translated addresses,
* discovering the shape of the CFG and finding loops,
* purging translations that get invalidated by overwrites (like self-modifying code),
* sprinkling the translated code full of guards so we can make assumptions about the original code
etc. All this is unnecessary for WASM and you can in fact make a quick and dirty one-pass translation for the 1st gear. I don't know, but it seems reasonable that they would keep the same FP->Int semantics as JS, but you rarely do that in non-JS code.
Because of this I find WASM to be the best direction yet for a "universal ISA" as it's very feasible to translate to most strange new radical architecture (like EDGE, Prodigy, etc). (Introducing a new ISA is almost impossible due to the cost of porting the world. RISC-V might be the last to succeed).