[COMMITTED] Normalize irange_bitmask before union/intersect.

[COMMITTED] Normalize irange_bitmask before union/intersect.

[Aldy Hernandez]

The bit twiddling in union/intersect for the value/mask pair must be
normalized to have the unknown bits with a value of 0 in order to make
the math simpler.  Normalizing at construction slowed VRP by 1.5% so I
opted to normalize before updating the bitmask in range-ops, since it
was the only user.  However, with upcoming changes there will be
multiple setters of the mask (IPA and CCP), so we need something more
general.

I played with various alternatives, and settled on normalizing before
union/intersect which were the ones needing the bits cleared.  With
this patch, there's no noticeable difference in performance either in
VRP or in overall compilation.

gcc/ChangeLog:

	* value-range.cc (irange_bitmask::verify_mask): Mask need not be
	normalized.
	* value-range.h (irange_bitmask::union_): Normalize beforehand.
	(irange_bitmask::intersect): Same.
---
 gcc/value-range.cc |  3 ---
 gcc/value-range.h  | 12 ++++++++++--
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/gcc/value-range.cc b/gcc/value-range.cc
index 011bdbdeae6..2abf57bcee8 100644
--- a/gcc/value-range.cc
+++ b/gcc/value-range.cc
@@ -1953,9 +1953,6 @@ void
 irange_bitmask::verify_mask () const
 {
   gcc_assert (m_value.get_precision () == m_mask.get_precision ());
-  // Unknown bits must have their corresponding value bits cleared as
-  // it simplifies union and intersect.
-  gcc_assert (wi::bit_and (m_mask, m_value) == 0);
 }
 
 void
diff --git a/gcc/value-range.h b/gcc/value-range.h
index 0170188201b..d8af6fca7d7 100644
--- a/gcc/value-range.h
+++ b/gcc/value-range.h
@@ -211,8 +211,12 @@ irange_bitmask::operator== (const irange_bitmask &src) const
 }
 
 inline bool
-irange_bitmask::union_ (const irange_bitmask &src)
+irange_bitmask::union_ (const irange_bitmask &orig_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;
@@ -222,8 +226,12 @@ irange_bitmask::union_ (const irange_bitmask &src)
 }
 
 inline bool
-irange_bitmask::intersect (const irange_bitmask &src)
+irange_bitmask::intersect (const irange_bitmask &orig_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
-- 
2.40.1

[COMMITTED] Add global setter for value/mask pair for SSA names.

[Aldy Hernandez]

This patch provides a way to set the value/mask pair of known bits
globally, similarly to how we can use set_nonzero_bits for known 0
bits.  This can then be used by CCP and IPA to set value/mask info
instead of throwing away the known 1 bits.

In further clean-ups, I will see if it makes sense to remove
set_nonzero_bits altogether, since it is subsumed by value/mask.

gcc/ChangeLog:

	* tree-ssanames.cc (set_bitmask): New.
	* tree-ssanames.h (set_bitmask): New.
---
 gcc/tree-ssanames.cc | 15 +++++++++++++++
 gcc/tree-ssanames.h  |  1 +
 2 files changed, 16 insertions(+)

diff --git a/gcc/tree-ssanames.cc b/gcc/tree-ssanames.cc
index 5fdb6a37e9f..f54394363a0 100644
--- a/gcc/tree-ssanames.cc
+++ b/gcc/tree-ssanames.cc
@@ -465,6 +465,21 @@ set_nonzero_bits (tree name, const wide_int &mask)
   set_range_info (name, r);
 }
 
+/* Update the known bits of NAME.
+
+   Zero bits in MASK cover constant values.  Set bits in MASK cover
+   unknown values.  VALUE are the known bits.  */
+
+void
+set_bitmask (tree name, const wide_int &value, const wide_int &mask)
+{
+  gcc_assert (!POINTER_TYPE_P (TREE_TYPE (name)));
+
+  int_range<2> r (TREE_TYPE (name));
+  r.update_bitmask (irange_bitmask (value, mask));
+  set_range_info (name, r);
+}
+
 /* Return a widest_int with potentially non-zero bits in SSA_NAME
    NAME, the constant for INTEGER_CST, or -1 if unknown.  */
 
diff --git a/gcc/tree-ssanames.h b/gcc/tree-ssanames.h
index f3fa609208a..b5e3f228ee8 100644
--- a/gcc/tree-ssanames.h
+++ b/gcc/tree-ssanames.h
@@ -59,6 +59,7 @@ struct GTY(()) ptr_info_def
 /* Sets the value range to SSA.  */
 extern bool set_range_info (tree, const vrange &);
 extern void set_nonzero_bits (tree, const wide_int &);
+extern void set_bitmask (tree, const wide_int &value, const wide_int &mask);
 extern wide_int get_nonzero_bits (const_tree);
 extern bool ssa_name_has_boolean_range (tree);
 extern void init_ssanames (struct function *, int);
-- 
2.40.1