* Fix profile_count::apply_probability
@ 2023-07-27 14:19 Jan Hubicka
0 siblings, 0 replies; only message in thread
From: Jan Hubicka @ 2023-07-27 14:19 UTC (permalink / raw)
To: gcc-patches
Hi,
profile_count::apply_probability misses check for uninitialized
probability which leads to completely random results on applying
uninitialized probability to initialized scale. This can make
difference when i.e. inlining -fno-guess-branch-probability function to
-fguess-branch-probability one.
Boootstrapped/regtested x86_64-linux, commited.
gcc/ChangeLog:
* profile-count.h (profile_count::apply_probability): Fix
handling of uninitialized probabilities, optimize scaling
by probability 1.
diff --git a/gcc/profile-count.h b/gcc/profile-count.h
index bf1136782a3..e860c5db540 100644
--- a/gcc/profile-count.h
+++ b/gcc/profile-count.h
@@ -1129,11 +1132,11 @@ public:
/* Scale counter according to PROB. */
profile_count apply_probability (profile_probability prob) const
{
- if (*this == zero ())
+ if (*this == zero () || prob == profile_probability::always ())
return *this;
if (prob == profile_probability::never ())
return zero ();
- if (!initialized_p ())
+ if (!initialized_p () || !prob.initialized_p ())
return uninitialized ();
profile_count ret;
uint64_t tmp;
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