Global store-to-load forwarding

Start by unpacking repro.tar.gz and running the provided wasm-opt command with the listed feature flags. Compare the resulting WAT with the requested transformations and read related issues 8016 and 8002. Done means the immutable global and struct-field loads are forwarded to the shown constants and imported global without changing behavior.

This is similar to https://github.com/WebAssembly/binaryen/issues/8016 & https://github.com/WebAssembly/binaryen/issues/8002

See this repro.tar.gz. The optimized version was obtained via open world compilation

% wasm-opt \
  --enable-gc --enable-reference-types --enable-multivalue --enable-exception-handling --enable-nontrapping-float-to-int \
  --enable-sign-ext --enable-bulk-memory --enable-threads \
 --enable-simd '--no-inline=*<noInline>*' --traps-never-happen \
  -g -Os -Os -Os \
  repro.wasm -o repro.opt.wasm

It leaves the following behind

  (type $JSExternWrapper (sub $Object (struct
    (field $field0 i32)
    (field $field1 (mut i32))
    (field $_externRef externref))))

  (global $.a (import "" "a") (ref extern))
  (global $"C284 \"a\"" (ref $JSExternWrapper) (i32.const 97) (i32.const 0) (global.get $.a) (struct.new $JSExternWrapper))

  (func $"findExact <noInline>" (param $var0 (ref $JSExternWrapper)) (result i64)
    (local $var1 (ref $JSExternWrapper))
    block $label0
      block $label1
        block $label2
          block $label3 (result i32)
            block $label4
              global.get $"C284 \"a\""
              local.tee $var1
              struct.get $JSExternWrapper $field0
              i32.const 97
              i32.ne
              br_if $label4
              local.get $var0
              struct.get $JSExternWrapper $_externRef
              local.get $var1
              struct.get $JSExternWrapper $_externRef
              call $"wasm:js-string.equals (import)"
              i32.eqz
              br_if $label4
              i32.const 1
              br $label3
            end $label4
            i32.const 0
          end $label3
          i32.eqz

Notice that the

• $C284 global is a non mutable global with known values being initialized
• $JSExternWrapper.$field0 is a non mutable i32 field
  Therefore the

              global.get $"C284 \"a\""
              local.tee $var1
              struct.get $JSExternWrapper $field0

should be turned into

              i32.const 97

and the

              local.get $var1
              struct.get $JSExternWrapper $_externRef

should be turned into

             global.get $.a