[Bug rtl-optimization/83913] [6/7/8 Regression] Compile time and memory hog w/ selective scheduling
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83913 --- Comment #4 from Andrey Belevantsev --- Author: abel Date: Mon Apr 9 09:42:25 2018 New Revision: 259230 URL: https://gcc.gnu.org/viewcvs?rev=259230=gcc=rev Log: PR rtl-optimization/83913 * sel-sched-ir.c (merge_expr_data): Choose the middle between two different sched-times when merging exprs. * gcc.dg/pr83913.c: New test. Added: trunk/gcc/testsuite/gcc.dg/pr83913.c Modified: trunk/gcc/ChangeLog trunk/gcc/sel-sched-ir.c trunk/gcc/testsuite/ChangeLog
[Bug rtl-optimization/83913] [6/7/8 Regression] Compile time and memory hog w/ selective scheduling
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83913
Andrey Belevantsev changed:
What|Removed |Added
Assignee|unassigned at gcc dot gnu.org |abel at gcc dot gnu.org
--- Comment #3 from Andrey Belevantsev ---
We've discussed with Alexander about this one. The simpler fix will be never
pipelining anything of priority 0, as this wouldn't give any benefit. The
better fix is to make bookkeeping copies within the pipelined region inherit
sched_times -- the number of times this insn was scheduled. It will not work
for regular scheduling as those new insns have to be scheduled at some point,
but for pipelined regions we're rescheduling blocks with new insns anyways. So
something like below works, but for that kind of patch I will need testing on
ia64 and it takes time.
diff --git a/gcc/sel-sched.c b/gcc/sel-sched.c
index 76092f9587a..58f4ca4016f 100644
--- a/gcc/sel-sched.c
+++ b/gcc/sel-sched.c
@@ -4773,7 +4773,16 @@ emit_bookkeeping_insn (insn_t place_to_insert, expr_t
c_expr, int new_seqno)
insn_t new_insn = emit_insn_from_expr_after (c_expr, new_vinsn, new_seqno,
place_to_insert);
- INSN_SCHED_TIMES (new_insn) = 0;
+ if (pipelining_p && !sel_is_loop_preheader_p (BLOCK_FOR_INSN
(place_to_insert)))
+{
+ int sched_times = EXPR_SCHED_TIMES (c_expr);
+ if (sched_times < 0)
+ sched_times = 0;
+ INSN_SCHED_TIMES (new_insn) = sched_times;
+}
+ else
+INSN_SCHED_TIMES (new_insn) = 0;
+
bitmap_set_bit (current_copies, INSN_UID (new_insn));
return new_insn;
[Bug rtl-optimization/83913] [6/7/8 Regression] Compile time and memory hog w/ selective scheduling
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83913 --- Comment #2 from Alexander Monakov --- Thanks. While I could not find why we blow up with Haswell tuning but not say Sandybridge, the main problem is that with all those -fno-... flags we have a few insns of the form rK = rN where rN is loop-invariant and rK is unused, so the insns are movable anywhere, including across the loop backedge (since pipelining is enabled). We try to fill schedule holes (caused by long-latency integer division insns) by repeatedly pipelining them. Eventually sched_times cut off should prevent that, but it doesn't grow as intended because bookkeeping copies get sched_times 0, and expr merging takes the minimum of two sched_times.
[Bug rtl-optimization/83913] [6/7/8 Regression] Compile time and memory hog w/ selective scheduling
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83913 Richard Biener changed: What|Removed |Added Priority|P3 |P2
[Bug rtl-optimization/83913] [6/7/8 Regression] Compile time and memory hog w/ selective scheduling
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83913 Jakub Jelinek changed: What|Removed |Added Status|UNCONFIRMED |NEW Last reconfirmed||2018-01-17 CC||abel at gcc dot gnu.org, ||amonakov at gcc dot gnu.org, ||hubicka at gcc dot gnu.org, ||jakub at gcc dot gnu.org Target Milestone|--- |6.5 Summary|[8 Regression] Compile time |[6/7/8 Regression] Compile |and memory hog w/ selective |time and memory hog w/ |scheduling |selective scheduling Ever confirmed|0 |1 --- Comment #1 from Jakub Jelinek --- Started with r255395. With additional -mtune=haswell it started in r227740 when the Haswell pipeline description had been added.
