Re: min/max macros

[Marc Lehmann <pcg at goof dot com>]

> > so egcs isn't a decent compiler?
> > 
> > for example, the macro-max(2,3) will be evaluated at compile time,
> > while the function-max(2,3) won't...
> 
> The function max(2,3) will indeed be evaluated at compile time, if it is
> inlined.

sorry, I was just too fast here in replyÄing (and I left the [EGCS] in, soory again ;)

> > this get's even worse on things like:
> > 
> > int mult(int a, int b) { return a*b; };
> > 
> > mult(a,3) will result in an "imul 3" on x86... definitely
> > slower than a lea, for example.
> 
> Same for mult: if it is inlined, it will be evaluated at compile time if
> given constant arguments.

no, mult(a,3) results in:

        movl 4(%esp),%eax
        imull $3,%eax,%eax
        ret

which is highly suboptimal.. a mult(4,5), though, will be evaluated at compile
time. But macros *are* faster than inline functions, despite what the
documentation tells us.


  ---------------------------------------------------------------------

      for a pentium-optimizing gcc, look at http://www.gcc.ml.org/

      -----==-                                              |
      ----==-- _                                            |
      ---==---(_)__  __ ____  __       Marc Lehmann       +--
      --==---/ / _ \/ // /\ \/ /       pcg@goof.com       |e|
      -=====/_/_//_/\_,_/ /_/\_\                          --+
    The choice of a GNU generation                        |
                                                          |