[Feature] Optimize logical operators for non-expression arguments

[MaxGraey]

Not sure is this optimization logic should be part of binaryen, because it can optimize simple low-level operations. Let me describe what I mean. Suppose we have a logical operation on two variables (not expressions), then we could easily optimize such an operation to a bitwise operations:

export function nonOptimal1(a: u32, b: u32): bool {
  return (a || b) ? true : false;
}

export function nonOptimal2(a: u32, b: u32): bool {
  return <bool>(a || b);
}

export function optimal(a: u32, b: u32): bool {
  return <bool>(a | b);
}

Output for nonOptimal1 (-O3):

(func $main/nonOptimal1 (export "nonOptimal1") (type $t0) (param $p0 i32) (param $p1 i32) (result i32)
    get_local $p0
    i32.eqz
    if $I0
      get_local $p1
      set_local $p0
    end
    get_local $p0
    if $I1 (result i32)
      i32.const 1
    else
      i32.const 0
    end
    tee_local $p0)

Output for optimal (-O3):

(func $main/optimal (export "optimal") (type $t0) (param $p0 i32) (param $p1 i32) (result i32)
    get_local $p0
    get_local $p1
    i32.or
    i32.const 0
    i32.ne)

[MaxGraey]

Similar code on Rust:

#[no_mangle]
pub extern "C" fn worstest(a: u32, b: u32) -> bool {
  return if a != 0 || b != 0 { true } else { false };
}

Output:

(func $worstest (export "worstest") (type $t0) (param $p0 i32) (param $p1 i32) (result i32)
    get_local $p1
    get_local $p0
    i32.or
    i32.const 0
    i32.ne)

[dcodeIO]

@MaxGraey Should this remain open, or has this meanwhile been escalated to the Binaryen side of things?

[MaxGraey]

Hmm, good question. It will try handle this on binaryen side. So you could close this