while-loop.zir

fn entry(start_index: usize, slice: []usize, value: usize) ?usize {
    var i: usize = start_index;

    while (i >= 0) : (i -= 1) {
        if (slice[i] == value) {
            return i;
        }
    }

    return null;
}


@v = voidvalue()
@usize = primitive(usize)
@OptUsize = optionaltype(@usize)
@Slice = slicetype(@usize)
@0 = int(0)
@1 = int(1)
@Fn = fntype([@usize, @Slice, @usize], @OptUsize)
@2 = fn(@Fn, {
  %i_ptr = alloca(@usize)
  %start_index = deref(%0)
  store(%i_ptr, %start_index)
  label(break, {
    loop({
      label(continue, {
        %i = deref(%i_ptr)
        %cond = cmp(%i, gte, @0)
        condbr(%cond, {
          ; loop body

          %eptr = elemptr(%1, %i)
          %elem = deref(%eptr)
          %value = deref(%2)
          %eq = cmp(%elem, eq, %value)
          label(if, {
            condbr(%eq, {
              return(%i)
            }, {
              merge(if, @v)
            })
          })

          merge(continue, @v)
        }, {
          merge(break, @v)
        })
      })
      %i = deref(%i_ptr)
      %new_i = add(%i, @1)
      store(%i_ptr, %new_i)
      repeat()
    })
  })
  %null = null()
  return(%null)
})
@3 = str("entry")
@4 = export(@3, @2)