Loop unrolling

Mike Stump mrs@wrs.com
Fri Jun 12 18:49:00 GMT 1998


> To: Richard Henderson <rth@cygnus.com>
> Cc: Mike Stump <mrs@wrs.com>, amylaar@cygnus.co.uk, egcs-patches@cygnus.com,
>         egcs@cygnus.com, pfeifer@dbai.tuwien.ac.at
> From: Alexandre Oliva <oliva@dcc.unicamp.br>
> Date: 12 Jun 1998 17:16:24 -0300
> X-Emacs: 20.4 "Emerald" XEmacs  Lucid without mule

> Richard Henderson <rth@cygnus.com> writes:

> Someone once has suggested a special syntax to denote an empty loop:

> for (i=0; i<10; ++i) {{;;}}

> The {{;;}} sequence would be recognized by gcc as a special token,
> that expanded to a special RTL node that marked the enclosing loop as
> non-removable.

This is wrong.  It was that we wanted the simple form to be
non-removable.  If we decide to change this, then we will just to to
remove any and all special handling, and just require the use
volatile...  not do anything like the above.

Now, if you want it to be removable, then we can make the above be
removable, and make only the ``;'' and ``{}'' forms non-removable, or
maybe just the ``;'' form.



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