https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83497
Bug ID: 83497
Summary: CPU2000 172.mgrid starts failing with r254730
Product: gcc
Version: 8.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: other
Assignee: unassigned at gcc dot gnu.org
Reporter: pthaugen at gcc dot gnu.org
CC: dje at gcc dot gnu.org, hubicka at gcc dot gnu.org,
rguenth at gcc dot gnu.org, segher at gcc dot gnu.org,
wschmidt at gcc dot gnu.org
Target Milestone: ---
Host: powerpc64-unknown-linux-gnu
Target: powerpc64-unknown-linux-gnu
Build: powerpc64-unknown-linux-gnu
mgrid started failing (output miscompare) with r254730. The following options
demonstrate the failure "-O3 -mcpu=power6 -ffast-math". The miscompared output
is...
29748: -0.839533E-12
0.182462E-12
^
29749: -0.839533E-12
0.182462E-12
^
29750: -0.849589E-12
0.184648E-12
^
29751: -0.849589E-12
0.184648E-12
^
29752: -0.852151E-12
0.185205E-12
^
29753: -0.852151E-12
0.185205E-12
^
29754: -0.852839E-12
0.185354E-12
^
A little brief history on this since it's come and gone a couple times. All
revisions deal with CFG/inlining issues.
r254730 - initial failure
r254937 - started working, only because this inadvertently disabled some
inlining
r254946 - fixed inlining from 254937, benchmark started failing again
r255103 - started working
So even though it's currently working on trunk I think there's an issue in
r255103 which I've emailed Honza about separately. If I apply the following
(which hopefully Honza will confirm is the desired behavior) to current trunk
the benchmark fails again.
Index: gcc/ipa-inline.c
===================================================================
--- gcc/ipa-inline.c (revision 255838)
+++ gcc/ipa-inline.c (working copy)
@@ -691,7 +691,7 @@
sreal time = compute_uninlined_call_time (e, unspec_time);
sreal inlined_time = compute_inlined_call_time (e, spec_time);
- if (time - inlined_time * 100
+ if ((time - inlined_time) * 100
> (sreal) (time * PARAM_VALUE (PARAM_INLINE_MIN_SPEEDUP)))
return true;
return false;
