Introduce assign_modify_operation

This adds class assign_modify_operation, which implements
BINOP_ASSIGN_MODIFY.

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

	* expop.h (class assign_modify_operation): New.
	* eval.c (eval_binop_assign_modify): No longer static.
	* ax-gdb.c (assign_modify_operation::do_generate_ax): New method.

1 files changed, 36 insertions, 0 deletions

diff --git a/gdb/expop.h b/gdb/expop.h
index 0f22365..93af40d 100644
--- a/gdb/expop.h
+++ b/gdb/expop.h
@@ -197,6 +197,12 @@ extern struct value *eval_op_memval (struct type *expect_type,
 				     struct expression *exp,
 				     enum noside noside,
 				     struct value *arg1, struct type *type);
+extern struct value *eval_binop_assign_modify (struct type *expect_type,
+					       struct expression *exp,
+					       enum noside noside,
+					       enum exp_opcode op,
+					       struct value *arg1,
+					       struct value *arg2);
 
 namespace expr
 {
@@ -1800,6 +1806,36 @@ protected:
     override;
 };
 
+/* Assignment with modification, like "+=".  */
+class assign_modify_operation
+  : public tuple_holding_operation<exp_opcode, operation_up, operation_up>
+{
+public:
+
+  using tuple_holding_operation::tuple_holding_operation;
+
+  value *evaluate (struct type *expect_type,
+		   struct expression *exp,
+		   enum noside noside) override
+  {
+    value *lhs = std::get<1> (m_storage)->evaluate (nullptr, exp, noside);
+    value *rhs = std::get<2> (m_storage)->evaluate (expect_type, exp, noside);
+    return eval_binop_assign_modify (expect_type, exp, noside,
+				     std::get<0> (m_storage), lhs, rhs);
+  }
+
+  enum exp_opcode opcode () const override
+  { return BINOP_ASSIGN_MODIFY; }
+
+protected:
+
+  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 */