[PATCH 2/5] range: Make range_op_table a true singleton class [PR116209]

[Andrew Pinski]

This is a small cleanup with respect to the ranger_op_table class.
There should only ever be one instance of ranger_op_table so
this adds a static member function which returns the instance.
A few variables that are defined in range-op.cc should be local
to the file so wrap them with an anonymous namespace.
Also change operator_table into a reference that is initialized to
the singelton.

This has a small extra overhead at intiialization time of the operator_table;
could be improved if we used C++20's consteval. Since this happens only once,
there it should be ok.

Bootstrapped and tested on x86_64-linux-gnu.

        PR tree-optimization/116209
gcc/ChangeLog:

        * range-op.cc (op_equal, op_not_equal, op_lt, op_le, op_gt, op_ge,
        op_ident, op_cst, op_cast, op_plus, op_abs, op_minus, op_negate,
        op_mult, op_addr, op_bitwise_not, op_bitwise_xor, op_bitwise_and,
        op_bitwise_or, op_min, op_max, default_operator): Wrap with anonymous 
namespace.
        (operator_table): Change to reference and initialize with 
range_op_table::singleton.
        (range_op_table::singleton): New function.
        * range-op.h (range_op_table): New method, singleton.
        Make most functions private (rather than protected).
        Make ctor private.

Signed-off-by: Andrew Pinski <quic_apin...@quicinc.com>
---
 gcc/range-op.cc | 19 ++++++++++++++-----
 gcc/range-op.h  |  5 +++--
 2 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/gcc/range-op.cc b/gcc/range-op.cc
index c576f688221..56a014e99bc 100644
--- a/gcc/range-op.cc
+++ b/gcc/range-op.cc
@@ -49,8 +49,9 @@ along with GCC; see the file COPYING3.  If not see
 #include "tree-ssa-ccp.h"
 #include "range-op-mixed.h"
 
-// Instantiate the operators which apply to multiple types here.
+namespace {
 
+// Instantiate the operators which apply to multiple types here.
 operator_equal op_equal;
 operator_not_equal op_not_equal;
 operator_lt op_lt;
@@ -74,7 +75,12 @@ operator_min op_min;
 operator_max op_max;
 
 // Instantaite a range operator table.
-range_op_table operator_table;
+range_op_table &operator_table = range_op_table::singleton();
+
+// Instantiate a default range operator for opcodes with no entry.
+range_operator default_operator;
+
+}
 
 // Invoke the initialization routines for each class of range.
 
@@ -111,9 +117,12 @@ range_op_table::range_op_table ()
   set (MAX_EXPR, op_max);
 }
 
-// Instantiate a default range operator for opcodes with no entry.
-
-range_operator default_operator;
+// Returns the singleton instance of the table.
+range_op_table &range_op_table::singleton()
+{
+  static range_op_table single;
+  return single;
+}
 
 // Create a default range_op_handler.
 
diff --git a/gcc/range-op.h b/gcc/range-op.h
index 8edf967a445..e4e11f89624 100644
--- a/gcc/range-op.h
+++ b/gcc/range-op.h
@@ -391,13 +391,13 @@ extern void wi_set_zero_nonzero_bits (tree type,
 class range_op_table final
 {
 public:
-  range_op_table ();
   inline range_operator *operator[] (unsigned code)
     {
       gcc_checking_assert (code < RANGE_OP_TABLE_SIZE);
       return m_range_tree[code];
     }
-protected:
+  static range_op_table &singleton();
+private:
   inline void set (unsigned code, range_operator &op)
     {
       gcc_checking_assert (code < RANGE_OP_TABLE_SIZE);
@@ -408,6 +408,7 @@ protected:
   void initialize_integral_ops ();
   void initialize_pointer_ops ();
   void initialize_float_ops ();
+  range_op_table ();
 };
 
 #endif // GCC_RANGE_OP_H
-- 
2.43.0