Extra pass for v128 operands in exported functions and globals?

At current moment, we can produce such code:

(func (export "a") $a (param $0 v128) (result v128) ;; [v128] -> [v128]
  local.get $0
  local.get $0
  i32x4.mul
 )

But web engines can't call functions with such signature. I'm not sure about standalone runtimes like wasmtime / wasmer, but web engines definitely not.

So I propose to add a new separate pass (at the end of pass pipeline) that would modify the code and the signature as follows:

(module
  (memory $0 1)
  ;; reserve temp data for return value of $a
  (data (i32.const 16) "\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00")
  
  (func (export "a") $a (param $0 i32) (result i32) ;; [i32] -> [i32]
    (local $1 v128)
    i32.const 16
    local.get $0
    v128.load
    local.tee $1
    local.get $1
    i32x4.mul
    v128.store
    i32.const 16
  )
 )

That is, now v128 values are stored and loaded from linear memory. WDYT?

No files, tests, or entry points are named. Start by locating the end of Binaryen’s pass pipeline and the handling of exported function and global signatures, then check the proposal against web-engine constraints. Done would require an agreed design and coverage for v128 operands in exported interfaces.