Re: Scripted pass manager

["Rob Quill" <rob dot quill at gmail dot com>]

On 29/11/2007, Richard Guenther <richard.guenther@gmail.com> wrote:
> On Nov 27, 2007 2:39 PM, Richard Guenther <richard.guenther@gmail.com> wrote:
> >
> > On Nov 26, 2007 11:20 PM, Rob Quill <rob.quill@gmail.com> wrote:
> > > Hi all,
> > >
> > > This patch scripts the pass manager in a way similar to the the
> > > options.c and options.h are generated. It shows no regressions against
> > > the current mainline on x86_64-linux.
> >
> > ;)
> >
> > With a "scripted pass manager" I of course ment a pass manager that
> > allows re-configuration of the pass pipeline without re-compiling.  For
> > example by embeding LUA (or another tiny scripting language).  With
> > control flow you should be able to experiment with looping over
> > optimization passes until nothing changes, etc., much like a simple
> > "plugin" interface without actually having plugins.
>
> Let me elaborate a bit on what I want from a 'scripted pass manager'.
> The statically specified pass pipeline is a limitation for experiments with
> pass ordering - so as a first thing I'd like to dynamically initialize the
> pass pipeline from - say - a textual description - that is either specified
> on the command-line or by looking up a default (which would match
> the current pipeline configuration) which is statically built into gcc.

So, as a starting point it would be better if the pass order was
decided at run time by a script instead of at compile time. So, to
check we're thinking along the same lines, I'm imagining that some
function/script would read the passes.def file at run-time and build
the pass list from this, e.g. very roughly

while(not EOF)
{
     char *s = read_next_line("passes.def");
     make_next_pass(s);
}

although if it was done from the command line, I suppose we would just
have for instance, some list of passes at run-time and turn these
somehow into the actually pass list? Is that would you had in mind?

Rob