Invalid local.set generation after store in `to_wasm_bytes`.

[SiebenCorgie]

Hi, I'm currently trying to generate WASM for a function-call with pass-by-reference arguments.
However, somehow the generated WASM does not match the Waffle-IR.

My function looks like this in pseudo Rust (the source language is a custom DSL):

fn my_function(a: &[f32; 3], result: &mut f32){
   //something interesting that writes to `result`
}

//the function that is compiled:
fn myfield(a: [f32; 3]) -> f32{
   let mut value;
   my_function(&a, &mut value);
   value - 1.0
} 

The following waffle print-out for the compiled function:

 function(f32, f32, f32) -> f32 {
   block0(v0: f32, v1: f32, v2: f32): #
     # preds:
     # succs:
     v3 = f32const<1065353216>  #
     v4 = i32const<1114112>  #
     v5 = f32store<memory0, align=0, offset=0> v4, v0 # i32, f32
     v6 = f32store<memory0, align=0, offset=4> v4, v1 # i32, f32
     v7 = f32store<memory0, align=0, offset=8> v4, v2 # i32, f32
     v8 = i32const<1114124>  #
     v9 = call<func156> v4, v8 # i32, i32
     v10 = f32load<memory0, align=0, offset=0> v8 # i32
     v11 = f32sub v10, v3 # f32, f32
     return v11
 }

However, after calling to_wasm_bytes I get the following invalid function via wasm-tools print:

(;@20451 ;)  (func $myfield (;334;) (type 5) (param f32 f32 f32) (result f32)
(;@20452 ;)    (local f32 f32 i32 i32)
(;@2045a ;)    i32.const 1114112
(;@2045f ;)    local.get 0
(;@20461 ;)    f32.store align=1
(;@20464 ;)    local.set 6
(;@20466 ;)    local.set 4
(;@20468 ;)    i32.const 1114112
(;@2046d ;)    local.get 1
(;@2046f ;)    f32.store offset=4 align=1
(;@20472 ;)    local.set 6
(;@20474 ;)    local.set 4
(;@20476 ;)    i32.const 1114112
(;@2047b ;)    local.get 2
(;@2047d ;)    f32.store offset=8 align=1
(;@20480 ;)    local.set 6
(;@20482 ;)    local.set 4
(;@20484 ;)    i32.const 1114112
(;@20489 ;)    i32.const 1114124
(;@2048e ;)    call $my_function
(;@20491 ;)    local.set 5
(;@20493 ;)    local.set 6
(;@20495 ;)    i32.const 1114124
(;@2049a ;)    f32.load align=1
(;@2049d ;)    f32.const 0x1p+0 (;=1;)
(;@204a2 ;)    f32.sub
(;@204a3 ;)    local.set 3
(;@204a5 ;)    local.set 4
(;@204a7 ;)    local.get 3
(;@204a9 ;)    return
             )

According to wasm-tools validate at 0x20464 the local.set6 is invalid, which is indeed true, since the first f32.store at 20461 consumed the static address, and the f32-value, and there is nothing on the stack anymore.

I'm aware that the mistake is probably on my site in the way I'm using waffle, but I don't see anything wrong with the waffle-IR snipped. As far as I'm aware f32.store does not push a value onto the stack, so there shouldn't be any stack-handling after that. Even if it would do so, the following local.set 4 would be wrong too.