http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56113
Richard Biener <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |jsm28 at gcc dot gnu.org --- Comment #14 from Richard Biener <rguenth at gcc dot gnu.org> 2013-01-29 15:38:24 UTC --- Run till exit from #0 update_label_decls (scope=0x7f32004f6c60) at /space/rguenther/src/svn/trunk/gcc/c/c-decl.c:1023 takes a long time for n = 50000. Seems to be quadratic (# of scopes times # of gotos). Re-writing the function into SSA takes a surprisingly large amount of memory and compile-time as well. I suppose using a special memory variable to factor the goto (one without virtual operands) would make this cheaper. Basically avoid going into SSA for it (avoid the gigantic PHI). Similar rewrite_into_loop_closed_ssa is slow. Next is PTA, but we know that already, the amount of extra memory used is reasonable now. Simple compile-time optimizations seem to be possible (we do a lot of redundant work in find_what_var_points_to by not caching the result for the representative). I have a patch to reduce (n = 10000) tree PTA : 25.37 (24%) usr 0.03 ( 3%) sys 25.44 (24%) wall 3125 kB ( 1%) ggc to tree PTA : 5.06 ( 6%) usr 0.02 ( 2%) sys 5.09 ( 6%) wall 937 kB ( 0%) ggc leaves tree SSA incremental : 34.14 (39%) usr 0.00 ( 0%) sys 34.22 (39%) wall 0 kB ( 0%) ggc as the biggest offender.