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* [gcc r15-41] Callers of irange_bitmask must normalize value/mask pairs.
@ 2024-04-28 19:04 Aldy Hernandez
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From: Aldy Hernandez @ 2024-04-28 19:04 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:d71308d5a681de008888ea291136c162e5b46c7c
commit r15-41-gd71308d5a681de008888ea291136c162e5b46c7c
Author: Aldy Hernandez <aldyh@redhat.com>
Date: Tue Apr 23 10:12:56 2024 +0200
Callers of irange_bitmask must normalize value/mask pairs.
As per the documentation, irange_bitmask must have the unknown bits in
the mask set to 0 in the value field. Even though we say we must have
normalized value/mask bits, we don't enforce it, opting to normalize
on the fly in union and intersect. Avoiding this lazy enforcing as
well as the extra saving/restoring involved in returning the changed
status, gives us a performance increase of 1.25% for VRP and 1.51% for
ipa-CP.
gcc/ChangeLog:
* tree-ssa-ccp.cc (ccp_finalize): Normalize before calling
set_bitmask.
* value-range.cc (irange::intersect_bitmask): Calculate changed
irange_bitmask bits on our own.
(irange::union_bitmask): Same.
(irange_bitmask::verify_mask): Verify that bits are normalized.
* value-range.h (irange_bitmask::union_): Do not normalize.
Remove return value.
(irange_bitmask::intersect): Same.
Diff:
---
gcc/tree-ssa-ccp.cc | 1 +
gcc/value-range.cc | 7 +++++--
gcc/value-range.h | 24 ++++++------------------
3 files changed, 12 insertions(+), 20 deletions(-)
diff --git a/gcc/tree-ssa-ccp.cc b/gcc/tree-ssa-ccp.cc
index f6a5cd0ee6e..3749126b5f7 100644
--- a/gcc/tree-ssa-ccp.cc
+++ b/gcc/tree-ssa-ccp.cc
@@ -1024,6 +1024,7 @@ ccp_finalize (bool nonzero_p)
unsigned int precision = TYPE_PRECISION (TREE_TYPE (val->value));
wide_int value = wi::to_wide (val->value);
wide_int mask = wide_int::from (val->mask, precision, UNSIGNED);
+ value = value & ~mask;
set_bitmask (name, value, mask);
}
}
diff --git a/gcc/value-range.cc b/gcc/value-range.cc
index a27de5534e1..ca6d521c625 100644
--- a/gcc/value-range.cc
+++ b/gcc/value-range.cc
@@ -2067,7 +2067,8 @@ irange::intersect_bitmask (const irange &r)
irange_bitmask bm = get_bitmask ();
irange_bitmask save = bm;
- if (!bm.intersect (r.get_bitmask ()))
+ bm.intersect (r.get_bitmask ());
+ if (save == bm)
return false;
m_bitmask = bm;
@@ -2099,7 +2100,8 @@ irange::union_bitmask (const irange &r)
irange_bitmask bm = get_bitmask ();
irange_bitmask save = bm;
- if (!bm.union_ (r.get_bitmask ()))
+ bm.union_ (r.get_bitmask ());
+ if (save == bm)
return false;
m_bitmask = bm;
@@ -2133,6 +2135,7 @@ void
irange_bitmask::verify_mask () const
{
gcc_assert (m_value.get_precision () == m_mask.get_precision ());
+ gcc_checking_assert (wi::bit_and (m_mask, m_value) == 0);
}
void
diff --git a/gcc/value-range.h b/gcc/value-range.h
index 0ab717697f0..11c73faca1b 100644
--- a/gcc/value-range.h
+++ b/gcc/value-range.h
@@ -139,8 +139,8 @@ public:
void set_unknown (unsigned prec);
bool unknown_p () const;
unsigned get_precision () const;
- bool union_ (const irange_bitmask &src);
- bool intersect (const irange_bitmask &src);
+ void union_ (const irange_bitmask &src);
+ void intersect (const irange_bitmask &src);
bool operator== (const irange_bitmask &src) const;
bool operator!= (const irange_bitmask &src) const { return !(*this == src); }
void verify_mask () const;
@@ -233,29 +233,18 @@ irange_bitmask::operator== (const irange_bitmask &src) const
return m_value == src.m_value && m_mask == src.m_mask;
}
-inline bool
-irange_bitmask::union_ (const irange_bitmask &orig_src)
+inline void
+irange_bitmask::union_ (const irange_bitmask &src)
{
- // Normalize mask.
- irange_bitmask src (orig_src.m_value & ~orig_src.m_mask, orig_src.m_mask);
- m_value &= ~m_mask;
-
- irange_bitmask save (*this);
m_mask = (m_mask | src.m_mask) | (m_value ^ src.m_value);
m_value = m_value & src.m_value;
if (flag_checking)
verify_mask ();
- return *this != save;
}
-inline bool
-irange_bitmask::intersect (const irange_bitmask &orig_src)
+inline void
+irange_bitmask::intersect (const irange_bitmask &src)
{
- // Normalize mask.
- irange_bitmask src (orig_src.m_value & ~orig_src.m_mask, orig_src.m_mask);
- m_value &= ~m_mask;
-
- irange_bitmask save (*this);
// If we have two known bits that are incompatible, the resulting
// bit is undefined. It is unclear whether we should set the entire
// range to UNDEFINED, or just a subset of it. For now, set the
@@ -274,7 +263,6 @@ irange_bitmask::intersect (const irange_bitmask &orig_src)
}
if (flag_checking)
verify_mask ();
- return *this != save;
}
// An integer range without any storage.
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