From: Phrogz <gavin@...>
Date: 2005-06-17T08:00:35+09:00
Subject: Super-scalar Optimizations

I was looking over the shoulder of a C++ coworker yesterday, when he
was writing a hack to only run certain code once. The C++ code was the
equivalent of the following Ruby code:

  already_run = false
  while true
    foo = bar if !already_run
    already_run = true
    do_something( )
  end

I asked him: "Wouldn't it be slightly faster to nest the boolean
assignment inside the if statement?" I was suggesting the equivalent
of:

  already_run = false
  while true
    if !already_run
      foo = bar
      already_run = true
    end
    do_something( )
  end

His answer was "no", and involved discussion of super-scalar
architectures and the fact that the original way ran the assignment in
parallel to the condition evaluation, and so was in fact faster.


The reason I'm posting is - are there any such considerations in Ruby
(when writing Ruby code, not C/C++ components)?

Or am I correct in assuming that the current state of
compilation/interpretation is such that there is no parallel branching
of statements to worry about?