Hello, When fwprop gets approved, CSE path following will disappear. We lose virtually no optimization opportunities. Still, it should not be very hard to make CSE work on extended basic blocks (but without rescanning like path following does). All that would be needed is infrastructure in cse.c to do a pre-order walk starting from some basic block, and a way to store and roll-back the state of the various tables that cse.c builds.
I found out long ago that even longer ago Vlad had patches to keep the state for basic blocks and re-using it. The latest message mentioning this work is http://gcc.gnu.org/ml/gcc-patches/2001-02/msg01166.html, and apparently Vlad's patches never made it out of the Cygnus network. So... Does anyone of you pack-rats still have these patches? Maybe there is code in them that I can re-use, or at least learn from because right now, even in my cleaned-up-and-cut-down version of cse.c (down to 5000 lines) I still can't make a whole lot of sense of all the tables that are used in that pass. I hope[*] you can help. Thanks, Gr. Steven [*] I know hope is delayed disappointment, but trying doesn't hurt ;-)
