@@ -651,13 +651,17 @@ ipa_merge_profiles (struct cgraph_node *dst,
{
edge srce = EDGE_SUCC (srcbb, i);
edge dste = EDGE_SUCC (dstbb, i);
- dste->probability =
+ profile_probability merged =
dste->probability * dstbb->count.ipa ().probability_in
(dstbb->count.ipa ()
+ srccount.ipa ())
+ srce->probability * srcbb->count.ipa ().probability_in
(dstbb->count.ipa ()
+ srccount.ipa ());
+ /* We produce uninitialized probabilities when
+ denominator is zero: https://gcc.gnu.org/PR111559. */
+ if (merged.initialized_p ())
+ dste->probability = merged;
}
dstbb->count = dstbb->count.ipa () + srccount.ipa ();
}
From: Sergei Trofimovich <siarheit@google.com> 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 during profile: __attribute__((noipa)) static void edge(void) {} int p = 0; __attribute__((noinline)) static void rule1(void) { if (p) edge(); } __attribute__((noinline)) static void rule1_same(void) { if (p) edge(); } __attribute__((noipa)) int main(void) { rule1(); rule1_same(); } $ gcc -O2 -fprofile-generate bug.c -o b -fopt-info $ ./b $ gcc -O2 -fprofile-use -fprofile-correction bug.c -o b -fopt-info bug.c: In function 'rule1': bug.c:6:13: error: probability of edge 3->4 not initialized 6 | static void rule1(void) { if (p) edge(); } | ^~~~~ during GIMPLE pass: fixup_cfg bug.c:6:13: internal compiler error: verify_flow_info failed The change conservatively ignores updates with uninitialized values and uses initially assigned probabilities (`always` probability in case of the example). gcc/ PR/111283 PR/111559 * ipa-utils.cc (ipa_merge_profiles): Avoid producing uninitialized probabilities when merging counters with zero denominators. --- gcc/ipa-utils.cc | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)