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Re: Need Help for GCC- common subexpression elimination


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On Mon, Oct 19, 2009 at 11:00, Adarsh malu <adarsh_there@yahoo.co.in> wrote:
>
> Hello,
> ÂÂÂÂÂÂ We are working on project with the target of Implement a pass to do available expression analysis & Using above information, implement a pass to add Common subexpression elimination optimization.
>  However we are unable to find documentation on the same and its being difficult for us to get througs the pass of cse.c , gcse.c as they being huge loc . Could you please elaborate us how to proceed and carry the project ahead.
> ÂÂÂÂÂ Any of your suggestion would really help us.

For available expressions, you may want to look at the code in
tree-ssa-pre.c and tree-ssa-sccvn.c.  They work on GIMPLE (a higher
level IL than RTL) which may be closer to what you are looking for.
The first file implements PRE and the second are routines used to
compute value numbers on gimple expressions.

You can see the effects of PRE with -fdump-tree-pre.

General documentation on GCC internals is available via
http://gcc.gnu.org/wiki/GettingStarted/


Diego.


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