Add overflow API for plus minus mult on range

In previous reviews, adding overflow APIs to range-op would be useful.
Those APIs could help to check if overflow happens when operating
between two 'range's, like: plus, minus, and mult.

Previous discussions are here:
https://gcc.gnu.org/pipermail/gcc-patches/2023-July/624067.html
https://gcc.gnu.org/pipermail/gcc-patches/2023-July/624701.html

gcc/ChangeLog:

	* range-op-mixed.h (operator_plus::overflow_free_p): New declare.
	(operator_minus::overflow_free_p): New declare.
	(operator_mult::overflow_free_p): New declare.
	* range-op.cc (range_op_handler::overflow_free_p): New function.
	(range_operator::overflow_free_p): New default function.
	(operator_plus::overflow_free_p): New function.
	(operator_minus::overflow_free_p): New function.
	(operator_mult::overflow_free_p): New function.
	* range-op.h (range_op_handler::overflow_free_p): New declare.
	(range_operator::overflow_free_p): New declare.
	* value-range.cc (irange::nonnegative_p): New function.
	(irange::nonpositive_p): New function.
	* value-range.h (irange::nonnegative_p): New declare.
	(irange::nonpositive_p): New declare.

1 files changed, 124 insertions, 0 deletions

diff --git a/gcc/range-op.cc b/gcc/range-op.cc
index 268f6b6..619979f 100644
--- a/gcc/range-op.cc
+++ b/gcc/range-op.cc
@@ -377,6 +377,22 @@ range_op_handler::op1_op2_relation (const vrange &lhs,
     }
 }
 
+bool
+range_op_handler::overflow_free_p (const vrange &lh,
+				   const vrange &rh,
+				   relation_trio rel) const
+{
+  gcc_checking_assert (m_operator);
+  switch (dispatch_kind (lh, lh, rh))
+    {
+      case RO_III:
+	return m_operator->overflow_free_p(as_a <irange> (lh),
+					   as_a <irange> (rh),
+					   rel);
+      default:
+	return false;
+    }
+}
 
 // Update the known bitmasks in R when applying the operation CODE to
 // LH and RH.
@@ -706,6 +722,13 @@ range_operator::op1_op2_relation_effect (irange &lhs_range ATTRIBUTE_UNUSED,
   return false;
 }
 
+bool
+range_operator::overflow_free_p (const irange &, const irange &,
+				 relation_trio) const
+{
+  return false;
+}
+
 // Apply any known bitmask updates based on this operator.
 
 void
@@ -4364,6 +4387,107 @@ range_op_table::initialize_integral_ops ()
 
 }
 
+bool
+operator_plus::overflow_free_p (const irange &lh, const irange &rh,
+				relation_trio) const
+{
+  if (lh.undefined_p () || rh.undefined_p ())
+    return false;
+
+  tree type = lh.type ();
+  if (TYPE_OVERFLOW_UNDEFINED (type))
+    return true;
+
+  wi::overflow_type ovf;
+  signop sgn = TYPE_SIGN (type);
+  wide_int wmax0 = lh.upper_bound ();
+  wide_int wmax1 = rh.upper_bound ();
+  wi::add (wmax0, wmax1, sgn, &ovf);
+  if (ovf != wi::OVF_NONE)
+    return false;
+
+  if (TYPE_UNSIGNED (type))
+    return true;
+
+  wide_int wmin0 = lh.lower_bound ();
+  wide_int wmin1 = rh.lower_bound ();
+  wi::add (wmin0, wmin1, sgn, &ovf);
+  if (ovf != wi::OVF_NONE)
+    return false;
+
+  return true;
+}
+
+bool
+operator_minus::overflow_free_p (const irange &lh, const irange &rh,
+				 relation_trio) const
+{
+  if (lh.undefined_p () || rh.undefined_p ())
+    return false;
+
+  tree type = lh.type ();
+  if (TYPE_OVERFLOW_UNDEFINED (type))
+    return true;
+
+  wi::overflow_type ovf;
+  signop sgn = TYPE_SIGN (type);
+  wide_int wmin0 = lh.lower_bound ();
+  wide_int wmax1 = rh.upper_bound ();
+  wi::sub (wmin0, wmax1, sgn, &ovf);
+  if (ovf != wi::OVF_NONE)
+    return false;
+
+  if (TYPE_UNSIGNED (type))
+    return true;
+
+  wide_int wmax0 = lh.upper_bound ();
+  wide_int wmin1 = rh.lower_bound ();
+  wi::sub (wmax0, wmin1, sgn, &ovf);
+  if (ovf != wi::OVF_NONE)
+    return false;
+
+  return true;
+}
+
+bool
+operator_mult::overflow_free_p (const irange &lh, const irange &rh,
+				relation_trio) const
+{
+  if (lh.undefined_p () || rh.undefined_p ())
+    return false;
+
+  tree type = lh.type ();
+  if (TYPE_OVERFLOW_UNDEFINED (type))
+    return true;
+
+  wi::overflow_type ovf;
+  signop sgn = TYPE_SIGN (type);
+  wide_int wmax0 = lh.upper_bound ();
+  wide_int wmax1 = rh.upper_bound ();
+  wi::mul (wmax0, wmax1, sgn, &ovf);
+  if (ovf != wi::OVF_NONE)
+    return false;
+
+  if (TYPE_UNSIGNED (type))
+    return true;
+
+  wide_int wmin0 = lh.lower_bound ();
+  wide_int wmin1 = rh.lower_bound ();
+  wi::mul (wmin0, wmin1, sgn, &ovf);
+  if (ovf != wi::OVF_NONE)
+    return false;
+
+  wi::mul (wmin0, wmax1, sgn, &ovf);
+  if (ovf != wi::OVF_NONE)
+    return false;
+
+  wi::mul (wmax0, wmin1, sgn, &ovf);
+  if (ovf != wi::OVF_NONE)
+    return false;
+
+  return true;
+}
+
 #if CHECKING_P
 #include "selftest.h"