> On 1/28/07, Jan Hubicka <[EMAIL PROTECTED]> wrote: > >I am not quite sure what you mean by direct inlining here. At -O2 G++ > Decorating everything in sight with attribute always_inline/noinline > (flatten wasn't an option because it used to be troublesome and not as > 'portable' across compilers).
BTW when inlining seems to make so noticeable difference, did you try to use profile feedback? > > >I would be interested to know about obvious mistakes GCC do - GCC now > >has logic to set cost of inlining "wrapper" functions (ie functions > >doing just one extra call and casts) to at most 0. It might be > >interesting to know if some common scenarios are missed. > I guess i should remove those attribute and see what it looks like. > > >Well, we are working on it ;) > >You can take a look at c++ benchmarks http://www.suse.de/~gcctest the > >work is ongoing since cgraph was implemented in 2003, another retunning > >happen at about 4.0 timeframe, 4.3 has the SSA based IPA that should be > >another improvement. > I'm aware of that progression and some of my code is already being tested > http://www.suse.de/~gcctest/c++bench/raytracer/ ;) I see, we didn't seem to make that much progress on this testcase performance wise yet ;) > >Concerning the frame sizes, we really need some kind of analysis from > >where it is comming - ie whether GCC simply inline too much together, or > >fail to pack well the structures using existing algorithm or it is > >register pressure problem. > I'm out of my league. I know the frontend_loop function isn't as > horrible on x86-64, giving some credit to the register pressure > hypothesis, but then that code isn't doing anything fancy. > > For the other function, which heavily uses SSE vector intrinsics, g++ > is really doing a good job, if only for the, sometimes, duplicated > structures here & there and the larger frame. But you can rule out > g++'s inlining heuristic as it has no (or shouldn't have) any freedom. Hmm, so then it should be esither structure packing or regalloc. I will be able to take a look only after returning from a course. Honza > > If there's anything i can do, do not hesitate. > And thanks for taking notice.
