Handle VIEW_CONVERT_EXPR for non-floats.

Handle VIEW_CONVERT_EXPR for ranges as if it were a cast.

	PR tree-optimization/91191
	gcc/
	* gimple-range-op.cc (gimple_range_op_handler): Descend one
	operand lower for a VIEW_CONVERT_EXPR.
	* range-op-mixed.h (class operator_view): New.
	* range-op.cc (range_op_table): Add VIEW_CONVERT_EXPR case.
	(operator_view::fold_range): New.
	(operator_view::op1_range): New.
	(operator_view::update_bitmask): New.

	gcc/testsuite/
	* gcc.dg/pr91191.c: New.

4 files changed, 141 insertions, 0 deletions

diff --git a/gcc/gimple-range-op.cc b/gcc/gimple-range-op.cc
index c9bc5c0..3a22606 100644
--- a/gcc/gimple-range-op.cc
+++ b/gcc/gimple-range-op.cc
@@ -150,6 +150,10 @@ gimple_range_op_handler::gimple_range_op_handler (gimple *s)
 	      if (TREE_CODE (ssa) == SSA_NAME)
 		m_op1 = ssa;
 	    }
+	  // VIEW_CONVERT_EXPR needs to descend one level deeper to pick
+	  // up the symbolic operand.
+	  if (TREE_CODE (m_op1) == VIEW_CONVERT_EXPR)
+	    m_op1 = TREE_OPERAND (m_op1, 0);
 	  if (gimple_num_ops (m_stmt) >= 3)
 	    m_op2 = gimple_assign_rhs2 (m_stmt);
 	  // Check that operands are supported types.  One check is enough.
diff --git a/gcc/range-op-mixed.h b/gcc/range-op-mixed.h
index 567b0cd..db31c2b 100644
--- a/gcc/range-op-mixed.h
+++ b/gcc/range-op-mixed.h
@@ -527,6 +527,47 @@ private:
 			   const irange &outer) const;
 };
 
+
+class operator_view : public range_operator
+{
+public:
+  using range_operator::fold_range;
+  using range_operator::op1_range;
+  using range_operator::update_bitmask;
+  bool fold_range (irange &r, tree type,
+		   const irange &op1, const irange &op2,
+		   relation_trio rel = TRIO_VARYING) const override;
+  bool fold_range (prange &r, tree type,
+		   const prange &op1, const prange &op2,
+		   relation_trio rel = TRIO_VARYING) const final override;
+  bool fold_range (irange &r, tree type,
+		   const prange &op1, const irange &op2,
+		   relation_trio rel = TRIO_VARYING) const final override;
+  bool fold_range (prange &r, tree type,
+		   const irange &op1, const prange &op2,
+		   relation_trio rel = TRIO_VARYING) const final override;
+
+  bool op1_range (irange &r, tree type,
+		  const irange &lhs, const irange &op2,
+		  relation_trio rel = TRIO_VARYING) const override;
+  bool op1_range (prange &r, tree type,
+		  const prange &lhs, const prange &op2,
+		  relation_trio rel = TRIO_VARYING) const final override;
+  bool op1_range (irange &r, tree type,
+		  const prange &lhs, const irange &op2,
+		  relation_trio rel = TRIO_VARYING) const final override;
+  bool op1_range (prange &r, tree type,
+		  const irange &lhs, const prange &op2,
+		  relation_trio rel = TRIO_VARYING) const final override;
+
+  void update_bitmask (irange &r, const irange &lh,
+		       const irange &) const final override;
+private:
+// VIEW_CONVERT_EXPR works much like a cast between integral values, so use
+// the cast operator.  Non-integrals are not handled as yet.
+  operator_cast m_cast;
+};
+
 class operator_plus : public range_operator
 {
 public:
diff --git a/gcc/range-op.cc b/gcc/range-op.cc
index 6b6bf78..cf5b8fe 100644
--- a/gcc/range-op.cc
+++ b/gcc/range-op.cc
@@ -60,6 +60,7 @@ operator_ge op_ge;
 operator_identity op_ident;
 operator_cst op_cst;
 operator_cast op_cast;
+operator_view op_view;
 operator_plus op_plus;
 operator_abs op_abs;
 operator_minus op_minus;
@@ -97,6 +98,7 @@ range_op_table::range_op_table ()
   set (INTEGER_CST, op_cst);
   set (NOP_EXPR, op_cast);
   set (CONVERT_EXPR, op_cast);
+  set (VIEW_CONVERT_EXPR, op_view);
   set (FLOAT_EXPR, op_cast);
   set (FIX_TRUNC_EXPR, op_cast);
   set (PLUS_EXPR, op_plus);
@@ -3247,6 +3249,80 @@ operator_cast::op1_range (irange &r, tree type,
   return true;
 }
 
+// VIEW_CONVERT_EXPR works like a cast between integral values.
+// If the number of bits are not the same, behaviour is undefined,
+// so cast behaviour still works.
+
+bool
+operator_view::fold_range (irange &r, tree type,
+			   const irange &op1, const irange &op2,
+			   relation_trio rel) const
+{
+  return m_cast.fold_range (r, type, op1, op2, rel);
+}
+
+bool
+operator_view::fold_range (prange &r, tree type,
+			   const prange &op1, const prange &op2,
+			   relation_trio rel) const
+{
+  return m_cast.fold_range (r, type, op1, op2, rel);
+}
+bool
+operator_view::fold_range (irange &r, tree type,
+			   const prange &op1, const irange &op2,
+			   relation_trio rel) const
+{
+  return m_cast.fold_range (r, type, op1, op2, rel);
+}
+
+bool
+operator_view::fold_range (prange &r, tree type,
+			   const irange &op1, const prange &op2,
+			   relation_trio rel) const
+{
+  return m_cast.fold_range (r, type, op1, op2, rel);
+}
+
+bool
+operator_view::op1_range (irange &r, tree type,
+			  const irange &lhs, const irange &op2,
+			  relation_trio rel) const
+{
+  return m_cast.op1_range (r, type, lhs, op2, rel);
+}
+
+bool
+operator_view::op1_range (prange &r, tree type,
+			  const prange &lhs, const prange &op2,
+			  relation_trio rel) const
+{
+  return m_cast.op1_range (r, type, lhs, op2, rel);
+}
+
+bool
+operator_view::op1_range (irange &r, tree type,
+			  const prange &lhs, const irange &op2,
+			  relation_trio rel) const
+{
+  return m_cast.op1_range (r, type, lhs, op2, rel);
+}
+
+bool
+operator_view::op1_range (prange &r, tree type,
+			  const irange &lhs, const prange &op2,
+			  relation_trio rel) const
+{
+  return m_cast.op1_range (r, type, lhs, op2, rel);
+}
+
+void
+operator_view::update_bitmask (irange &r, const irange &lh,
+			       const irange &rh) const
+{
+  m_cast.update_bitmask (r, lh, rh);
+}
+
 
 class operator_logical_and : public range_operator
 {
diff --git a/gcc/testsuite/gcc.dg/pr91191.c b/gcc/testsuite/gcc.dg/pr91191.c
new file mode 100644
index 0000000..7bf727e
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr91191.c
@@ -0,0 +1,20 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-evrp" } */
+
+unsigned char reg(_Bool b) {
+    union U {
+        unsigned char f0;
+        _Bool f1;
+    };
+    union U u;
+    u.f1 = b;
+    if (u.f0 > 1) {
+        // This cannot happen
+        // if b is only allowed
+        // to be 0 or 1:
+        return 42;
+    }
+    return 13;
+}
+
+/* { dg-final { scan-tree-dump "return 13"  "evrp" } } */