preserving local: N to slot: N, m3NotImplemented about wasm3

[kgdev]

Both "local.get $1" would be replaced to a slot, saying 40. So slot 40 is referenced twice. When deallocating slot 40, we need to keep a count instead of just 1 or 0. Otherwise, I would get a Assertion failed: (o->m3Slots [i_slotIndex]), function DeallocateSlot.

Also the implementation of PreserveArgsAndLocals could be made more efficient. Instead of number of locals (n) x number of references (m), we could just use O(m) time.

[vshymanskyy]

@soundandform I think I have hit this a few times already, when working on self-hosting.

[kgdev]

Anyway I can help on this?

[soundandform]

I can fix. I had been waiting for this case to come up in an actual .wasm file.

[kgdev]

(module
  (type (func))
  (func (type 0)
    (local i32)
    local.get 0
    block
      i32.const 0
      local.set 0
    end
    drop
  )
  (memory 1)
)

[soundandform]

Hah. Thanks. Yeah, a contrived wasm file was the runner up option :)

[kgdev]

The sample actually comes from a real wasm of a game :)

[kgdev]

It seems that we have to insert the "preserve" local operation before the previous block. What's the best way to do that?

[kgdev]

Or just preserve all locals just before a block?

[kgdev]

#42

[kgdev]

@soundandform 4783048 doesn't seem to be right. For a "if" branch, the SetLocal could run or just not. In the latter case, replacing the local index in the stack would be wrong.

[soundandform]

@kgdev I haven't addressed loop and if yet which is why I said it was "partial."

[vshymanskyy]

I believe this is fixed now. @kgdev please verify

[vshymanskyy]

Should be OK now. Please report it still have problems with this