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Re: Add quality tracking for profile counter
- From: Jan Hubicka <hubicka at ucw dot cz>
- To: Andreas Schwab <schwab at suse dot de>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Thu, 22 Jun 2017 16:51:36 +0200
- Subject: Re: Add quality tracking for profile counter
- Authentication-results: sourceware.org; auth=none
- References: <20170619094949.GA49407@kam.mff.cuni.cz> <mvmk245bxg3.fsf@suse.de>
Hi,
I proofread the code and noticed that in some cases I may trigger division by 0 that may
get different outputs depending on optimization setting on Itanium.
This is what I comitted after profiledbootstrap and regtesting at x86_64.
* profile-count.h (apply_probability,
apply_scale, probability_in): Fix checks for zero.
Index: profile-count.h
===================================================================
--- profile-count.h (revision 249364)
+++ profile-count.h (working copy)
@@ -255,7 +255,7 @@ public:
profile_count apply_probability (int prob) const
{
gcc_checking_assert (prob >= 0 && prob <= REG_BR_PROB_BASE);
- if (*this == profile_count::zero ())
+ if (m_val == 0)
return *this;
if (!initialized_p ())
return profile_count::uninitialized ();
@@ -267,24 +267,25 @@ public:
/* Return *THIS * NUM / DEN. */
profile_count apply_scale (int64_t num, int64_t den) const
{
- if (*this == profile_count::zero ())
+ if (m_val == 0)
return *this;
if (!initialized_p ())
return profile_count::uninitialized ();
profile_count ret;
+ gcc_checking_assert (num >= 0 && den > 0);
/* FIXME: shrink wrapping violates this sanity check. */
- gcc_checking_assert ((num >= 0
- && (num <= REG_BR_PROB_BASE
- || den <= REG_BR_PROB_BASE)
- && den > 0) || 1);
+ gcc_checking_assert ((num <= REG_BR_PROB_BASE
+ || den <= REG_BR_PROB_BASE) || 1);
ret.m_val = RDIV (m_val * num, den);
ret.m_quality = MIN (m_quality, count_adjusted);
return ret;
}
profile_count apply_scale (profile_count num, profile_count den) const
{
- if (*this == profile_count::zero () || num == profile_count::zero ())
- return profile_count::zero ();
+ if (m_val == 0)
+ return *this;
+ if (num.m_val == 0)
+ return num;
if (!initialized_p () || !num.initialized_p () || !den.initialized_p ())
return profile_count::uninitialized ();
gcc_checking_assert (den > 0);
@@ -306,7 +307,7 @@ public:
OVERALL. */
int probability_in (profile_count overall)
{
- if (*this == profile_count::zero ())
+ if (!m_val)
return 0;
if (!initialized_p () || !overall.initialized_p ())
return REG_BR_PROB_BASE / 2;