Re: Intermodule constant propagation

[Andrew Pinski <pinskia@physics.uc.edu>]

On Nov 24, 2003, at 00:13, Mircea Namolaru wrote:
> We would like to add several interprocedural optimizations to gcc, 
> starting
> with constant propagation.
>
> We are thinking of implementing a flow insensitive form of the
> interprocedural
> constant propagation algorithm described in [1][2], based on the new
> intermodule code 
> (http://gcc.gnu.org/ml/gcc-patches/2003-05/msg01665.html).
>
> We would appreciate any feedback regarding gcc interprocedural
> optimizations
> (work done or in development, potential problems etc).


Jan Hubicka and I were just talking about this on IRC today.

Here is the ideas both Jan and I agreed on (for the tree-ssa branch):
Have a flag called -fwhole-prgram which tells GCC that the whole
program is being compiled at this point and have variables which
were global be static.

Have the code in callgraph (aka cgraph.c) do some of the work:
Have cgraph_analyze_function to collect the assigments and uses
of variables.

And have any changes to the functions happen in cgraph_expand_fuction.

The down side at this point is that the trees here are in generic and 
not
gimple but Jan is working on getting this problem solved.

I might have some work done by the end of the week on this front and 
basic
constant propagation IPA.

Thanks,
Andrew Pinski
pinskia@physics.uc.edu
pinskia@gcc.gnu.org
apinski@apple.com