| Message ID | 20180126231507.GD2063@tucnak |
|---|---|
| State | New |
| Headers | show |
| Series | Avoid O(n^2) compile time issue in sched2 with debug insns (PR middle-end/84040) | expand |
On 01/26/2018 06:15 PM, Jakub Jelinek wrote: > Hi! > > On a testcase which has 100000 consecutive debug insns sched2 spends > a lot of time calling prev_nonnote_nondebug_insn on each of the debug > insns, even when it is completely useless, because no target wants > to fuse a non-debug insn with some debug insn after it, it makes sense > only for two non-debug insns. > > By returning early for those, we'll just walk the long set of them once when > we process some non-debug instruction after a long block of debug insns. > > Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk? OK. > 2018-01-26 Jakub Jelinek <jakub@redhat.com> > > PR middle-end/84040 > * sched-deps.c (sched_macro_fuse_insns): Return immediately for > debug insns. > > --- gcc/sched-deps.c.jj 2018-01-03 10:19:56.301534141 +0100 > +++ gcc/sched-deps.c 2018-01-26 16:21:01.922414579 +0100 > @@ -2834,10 +2834,16 @@ static void > sched_macro_fuse_insns (rtx_insn *insn) > { > rtx_insn *prev; > + /* No target hook would return true for debug insn as any of the > + hook operand, and with very large sequences of only debug insns > + where on each we call sched_macro_fuse_insns it has quadratic > + compile time complexity. */ > + if (DEBUG_INSN_P (insn)) > + return; > prev = prev_nonnote_nondebug_insn (insn); > if (!prev) > return; > - > + > if (any_condjump_p (insn)) > { > unsigned int condreg1, condreg2;
--- gcc/sched-deps.c.jj 2018-01-03 10:19:56.301534141 +0100 +++ gcc/sched-deps.c 2018-01-26 16:21:01.922414579 +0100 @@ -2834,10 +2834,16 @@ static void sched_macro_fuse_insns (rtx_insn *insn) { rtx_insn *prev; + /* No target hook would return true for debug insn as any of the + hook operand, and with very large sequences of only debug insns + where on each we call sched_macro_fuse_insns it has quadratic + compile time complexity. */ + if (DEBUG_INSN_P (insn)) + return; prev = prev_nonnote_nondebug_insn (insn); if (!prev) return; - + if (any_condjump_p (insn)) { unsigned int condreg1, condreg2;