On Mon, Mar 5, 2012 at 9:52 AM, Arnaldo <arnaldo.c...@upr.edu> wrote: > On Mon, Mar 5, 2012 at 10:00 AM, Michael Matz <m...@suse.de> wrote: >> Hi, >> >> On Mon, 5 Mar 2012, Arnaldo wrote: >> >>> I couldn't get cfgexpand.c:basic_block expand_gimple_basic_block >>> (basic_block bb) to work by calling it directly because there is some >>> preprocessing in gimple_expand_cfg() that has to be done first. But >>> calling gimple_expand_cfg() modifies the CFG and asserts will fail later >>> on during compilation. >>> >>> I think the only way to solve this would be to somehow duplicate the >>> current cfun structure when entering the part of Graphite I'm extending, >>> then calling push_cfun(), gimple_expand_cfg(), extracting the BBs with >>> the RTL and calling pop_cfun() before continuing. >> >> Really, you're barking up the wrong tree. graphite doesn't work on the >> RTL IL, it'll work only on gimple. expanding is what we call the process >> of transforming gimple to RTL, and that process destroys gimple. Hence >> you can't do that when still at the gimple side of things as there are >> still passes to run that run in gimple. >> >> Whatever you want to do with graphite, you have to do it at the gimple >> level. >> >> >> Ciao, >> Michael. > > Richard, Michael, > > I have to find a way to generate the RTL because I have profiled an > instruction set and I need access to these costs during my extension > to the Graphite pass. I planed to add these costs as attributes to > the RTX patterns in the machine description file and read the back > from Graphite. Gimple seems to be too high-level to associate its > statements to machine costs. > > I know this is not the way GCC was designed but the optimization I'm > working on needs access to the profile. Maybe there's a better way of > doing this? What I'm attempting to do now is to duplicate the current > cfun so that I can expand and read the RTL attributes and then discard > this cfun before continuing with the compilation.
You can look in the SSA loop optimizations (tree-ssa-loop-ivopts.c?) for some code that basically compiles little snippets from GIMPLE to RTL, computes RTX costs, and then tries to map those back to GIMPLE. It's very ugly and limited accuracy. - David
