Hi! On Wed, Aug 12, 2020 at 09:03:35PM +0200, Richard Biener wrote: > On August 12, 2020 7:53:07 PM GMT+02:00, Jan Hubicka <hubi...@ucw.cz> wrote: > >> From: Xiong Hu Luo <luo...@linux.ibm.com> > >> 523.xalancbmk_r +1.32% > >> 541.leela_r +1.51% > >> 548.exchange2_r +31.87% > >> 507.cactuBSSN_r +0.80% > >> 526.blender_r +1.25% > >> 538.imagick_r +1.82%
> >> diff --git a/gcc/cgraph.h b/gcc/cgraph.h > >> index 0211f08964f..11903ac1960 100644 > >> --- a/gcc/cgraph.h > >> +++ b/gcc/cgraph.h > >> @@ -3314,6 +3314,8 @@ cgraph_edge::recursive_p (void) > >> cgraph_node *c = callee->ultimate_alias_target (); > >> if (caller->inlined_to) > >> return caller->inlined_to->decl == c->decl; > >> + else if (caller->clone_of && c->clone_of) > >> + return caller->clone_of->decl == c->clone_of->decl; > >> else > >> return caller->decl == c->decl; > > > >If you clone the function so it is no longer self recursive, it does > >not > >make much sense to lie to optimizers that the function is still > >recursive. Like Richard says below (if I understand him right, sorry if not), the function still *is* recursive in its group of clones. > >The inlining would be harmful even if the programer did cloning by > >hand. > >I guess main problem is the extreme register pressure issue combining > >loop depth of 10 in caller with loop depth of 10 in callee just because > >the function is called once. > > > >The negative effect is most likely also due to wrong profile estimate > >which drives IRA to optimize wrong spot. But I wonder if we simply > >don't want to teach inlining function called once to not construct > >large > >loop depths? Something like do not inline if caller&callee loop depth > >is over 3 or so? > > I don't think that's good by itself (consider leaf functions and x86 xmm reg > ABI across calls). Even with large loop depth abstraction penalty removal can > make inlining worth it. For the testcase the recursiveness is what looks > special (recursion from a deeper loop nest level). Yes, the loop stuff / register pressure issues might help for the exchange result, but what about the other five above? Segher
