Introduce var_msym_value_operation

This adds class var_msym_value_operation, which implements
OP_VAR_MSYM_VALUE.  A new method is added to class operation in order
to support a special case in minsym evaluation.

gdb/ChangeLog
2021-03-08  Tom Tromey  <tom@tromey.com>

	* expression.h (class operation) <set_outermost>: New method.
	* expop.h (class var_msym_value_operation): New.
	* eval.c (eval_op_var_msym_value): No longer static.
	(var_msym_value_operation::evaluate_for_address)
	(var_msym_value_operation::evaluate_for_sizeof)
	(var_msym_value_operation::evaluate_for_cast): New methods.
	* ax-gdb.c (var_msym_value_operation::do_generate_ax): New
	method.

1 files changed, 52 insertions, 0 deletions

diff --git a/gdb/expop.h b/gdb/expop.h
index ed883be..345cac2 100644
--- a/gdb/expop.h
+++ b/gdb/expop.h
@@ -45,6 +45,12 @@ extern struct value *eval_op_scope (struct type *expect_type,
 				    struct expression *exp,
 				    enum noside noside,
 				    struct type *type, const char *string);
+extern struct value *eval_op_var_msym_value (struct type *expect_type,
+					     struct expression *exp,
+					     enum noside noside,
+					     bool outermost_p,
+					     minimal_symbol *msymbol,
+					     struct objfile *objfile);
 
 namespace expr
 {
@@ -481,6 +487,52 @@ protected:
     override;
 };
 
+class var_msym_value_operation
+  : public maybe_constant_operation<minimal_symbol *, struct objfile *>
+{
+public:
+
+  using maybe_constant_operation::maybe_constant_operation;
+
+  value *evaluate (struct type *expect_type,
+		   struct expression *exp,
+		   enum noside noside) override
+  {
+    return eval_op_var_msym_value (expect_type, exp, noside, m_outermost,
+				   std::get<0> (m_storage),
+				   std::get<1> (m_storage));
+  }
+
+  value *evaluate_for_sizeof (struct expression *exp, enum noside noside)
+    override;
+
+  value *evaluate_for_address (struct expression *exp, enum noside noside)
+    override;
+
+  value *evaluate_for_cast (struct type *expect_type,
+			    struct expression *exp,
+			    enum noside noside) override;
+
+  enum exp_opcode opcode () const override
+  { return OP_VAR_MSYM_VALUE; }
+
+  void set_outermost () override
+  {
+    m_outermost = true;
+  }
+
+protected:
+
+  /* True if this is the outermost operation in the expression.  */
+  bool m_outermost = false;
+
+  void do_generate_ax (struct expression *exp,
+		       struct agent_expr *ax,
+		       struct axs_value *value,
+		       struct type *cast_type)
+    override;
+};
+
 } /* namespace expr */
 
 #endif /* EXPOP_H */