On Thu, Oct 05, 2023 at 03:04:55PM +0200, Jan Hubicka wrote:
> > diff --git a/gcc/ipa-utils.cc b/gcc/ipa-utils.cc
> > index 956c6294fd7..1355ccac6f0 100644
> > --- a/gcc/ipa-utils.cc
> > +++ b/gcc/ipa-utils.cc
> > @@ -651,13 +651,16 @@ ipa_merge_profiles (struct cgraph_node *dst,
> > {
> > edge srce = EDGE_SUCC (srcbb, i);
> > edge dste = EDGE_SUCC (dstbb, i);
> > - dste->probability =
> > - dste->probability * dstbb->count.ipa ().probability_in
> > -(dstbb->count.ipa ()
> > - + srccount.ipa ())
> > - + srce->probability * srcbb->count.ipa ().probability_in
> > -(dstbb->count.ipa ()
> > - + srccount.ipa ());
> > + profile_count sum =
> > + dstbb->count.ipa () + srccount.ipa ();
> > + if (sum.nonzero_p ())
> > + dste->probability =
> > + dste->probability * dstbb->count.ipa ().probability_in
> > + (dstbb->count.ipa ()
> > + + srccount.ipa ())
> > + + srce->probability * srcbb->count.ipa ().probability_in
> > + (dstbb->count.ipa ()
> > + + srccount.ipa ());
>
> looks good. You can use probability_in (sum)
> in both of the places.
Oh, great point! Completely forgot about it. Attached v4.
If it still looks reasonable I'll check again if `python` and
`profiledbootstrap` still survives it and will push.
--
Sergei
>From cb9852216b5b2524f72964b399c133557ec98df0 Mon Sep 17 00:00:00 2001
From: Sergei Trofimovich
Date: Wed, 27 Sep 2023 14:29:12 +0100
Subject: [PATCH v4] ipa-utils: avoid uninitialized probabilities on ICF
[PR111559]
r14-3459-g0c78240fd7d519 "Check that passes do not forget to define profile"
exposed check failures in cases when gcc produces uninitialized profile
probabilities. In case of PR/111559 uninitialized profile is generated
by edges executed 0 times reported by IPA profile:
$ gcc -O2 -fprofile-generate pr111559.c -o b -fopt-info
$ ./b
$ gcc -O2 -fprofile-use -fprofile-correction pr111559.c -o b -fopt-info
pr111559.c: In function 'rule1':
pr111559.c:6:13: error: probability of edge 3->4 not initialized
6 | static void rule1(void) { if (p) edge(); }
| ^
during GIMPLE pass: fixup_cfg
pr111559.c:6:13: internal compiler error: verify_flow_info failed
The change conservatively ignores updates with zero execution counts and
uses initially assigned probabilities (`always` probability in case of
the example).
PR ipa/111283
PR gcov-profile/111559
gcc/
* ipa-utils.cc (ipa_merge_profiles): Avoid producing
uninitialized probabilities when merging counters with zero
denominators.
gcc/testsuite/
* gcc.dg/tree-prof/pr111559.c: New test.
---
gcc/ipa-utils.cc | 15 ---
gcc/testsuite/gcc.dg/tree-prof/pr111559.c | 16
2 files changed, 24 insertions(+), 7 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/tree-prof/pr111559.c
diff --git a/gcc/ipa-utils.cc b/gcc/ipa-utils.cc
index 956c6294fd7..6024ac69cc2 100644
--- a/gcc/ipa-utils.cc
+++ b/gcc/ipa-utils.cc
@@ -651,13 +651,14 @@ ipa_merge_profiles (struct cgraph_node *dst,
{
edge srce = EDGE_SUCC (srcbb, i);
edge dste = EDGE_SUCC (dstbb, i);
- dste->probability =
- dste->probability * dstbb->count.ipa ().probability_in
-(dstbb->count.ipa ()
- + srccount.ipa ())
- + srce->probability * srcbb->count.ipa ().probability_in
-(dstbb->count.ipa ()
- + srccount.ipa ());
+ profile_count sum =
+ dstbb->count.ipa () + srccount.ipa ();
+ if (sum.nonzero_p ())
+ dste->probability =
+ dste->probability * dstbb->count.ipa ().probability_in
+ (sum)
+ + srce->probability * srcbb->count.ipa ().probability_in
+ (sum);
}
dstbb->count = dstbb->count.ipa () + srccount.ipa ();
