Add scoped_value_mark

This adds a scoped_value_mark class, that records the value mark in
the constructor and then calls value_free_to_mark in the destructor.
It then updates various spots in gdb to use this class, rather than a
cleanup.

It would be better overall to replace "struct value *" with a
shared_ptr, maybe eliminating the need for this class (watchpoints
would perhaps need some new mechanism as well).  However, that's
difficult to do.

2017-01-10  Tom Tromey  <tom@tromey.com>

	* python/py-value.c (valpy_dereference, valpy_referenced_value)
	(valpy_reference_value, valpy_const_value, valpy_get_address)
	(valpy_get_dynamic_type, valpy_lazy_string, valpy_do_cast)
	(valpy_getitem, valpy_call, valpy_binop_throw, valpy_negative)
	(valpy_absolute, valpy_richcompare_throw): Use scoped_value_mark.
	* dwarf2loc.c (dwarf2_loc_desc_get_symbol_read_needs): Use
	scoped_value_mark.
	* dwarf2-frame.c (execute_stack_op): Use scoped_value_mark.
	* value.h (scoped_value_mark): New class.

1 files changed, 18 insertions, 44 deletions

diff --git a/gdb/python/py-value.c b/gdb/python/py-value.c
index 97136e3141..8f3164b53c 100644
--- a/gdb/python/py-value.c
+++ b/gdb/python/py-value.c
@@ -178,11 +178,10 @@ valpy_dereference (PyObject *self, PyObject *args)
   TRY
     {
       struct value *res_val;
-      struct cleanup *cleanup = make_cleanup_value_free_to_mark (value_mark ());
+      scoped_value_mark free_values;
 
       res_val = value_ind (((value_object *) self)->value);
       result = value_to_value_object (res_val);
-      do_cleanups (cleanup);
     }
   CATCH (except, RETURN_MASK_ALL)
     {
@@ -209,7 +208,7 @@ valpy_referenced_value (PyObject *self, PyObject *args)
   TRY
     {
       struct value *self_val, *res_val;
-      struct cleanup *cleanup = make_cleanup_value_free_to_mark (value_mark ());
+      scoped_value_mark free_values;
 
       self_val = ((value_object *) self)->value;
       switch (TYPE_CODE (check_typedef (value_type (self_val))))
@@ -226,7 +225,6 @@ valpy_referenced_value (PyObject *self, PyObject *args)
         }
 
       result = value_to_value_object (res_val);
-      do_cleanups (cleanup);
     }
   CATCH (except, RETURN_MASK_ALL)
     {
@@ -247,12 +245,10 @@ valpy_reference_value (PyObject *self, PyObject *args)
   TRY
     {
       struct value *self_val;
-      struct cleanup *cleanup = make_cleanup_value_free_to_mark (value_mark ());
+      scoped_value_mark free_values;
 
       self_val = ((value_object *) self)->value;
       result = value_to_value_object (value_ref (self_val));
-
-      do_cleanups (cleanup);
     }
   CATCH (except, RETURN_MASK_ALL)
     {
@@ -273,13 +269,11 @@ valpy_const_value (PyObject *self, PyObject *args)
   TRY
     {
       struct value *self_val, *res_val;
-      struct cleanup *cleanup = make_cleanup_value_free_to_mark (value_mark ());
+      scoped_value_mark free_values;
 
       self_val = ((value_object *) self)->value;
       res_val = make_cv_value (1, 0, self_val);
       result = value_to_value_object (res_val);
-
-      do_cleanups (cleanup);
     }
   CATCH (except, RETURN_MASK_ALL)
     {
@@ -301,12 +295,10 @@ valpy_get_address (PyObject *self, void *closure)
       TRY
 	{
 	  struct value *res_val;
-	  struct cleanup *cleanup
-	    = make_cleanup_value_free_to_mark (value_mark ());
+	  scoped_value_mark free_values;
 
 	  res_val = value_addr (val_obj->value);
 	  val_obj->address = value_to_value_object (res_val);
-	  do_cleanups (cleanup);
 	}
       CATCH (except, RETURN_MASK_ALL)
 	{
@@ -354,7 +346,7 @@ valpy_get_dynamic_type (PyObject *self, void *closure)
   TRY
     {
       struct value *val = obj->value;
-      struct cleanup *cleanup = make_cleanup_value_free_to_mark (value_mark ());
+      scoped_value_mark free_values;
 
       type = value_type (val);
       type = check_typedef (type);
@@ -387,8 +379,6 @@ valpy_get_dynamic_type (PyObject *self, void *closure)
 	  /* Re-use object's static type.  */
 	  type = NULL;
 	}
-
-      do_cleanups (cleanup);
     }
   CATCH (except, RETURN_MASK_ALL)
     {
@@ -428,7 +418,7 @@ valpy_lazy_string (PyObject *self, PyObject *args, PyObject *kw)
 
   TRY
     {
-      struct cleanup *cleanup = make_cleanup_value_free_to_mark (value_mark ());
+      scoped_value_mark free_values;
 
       if (TYPE_CODE (value_type (value)) == TYPE_CODE_PTR)
 	value = value_ind (value);
@@ -436,8 +426,6 @@ valpy_lazy_string (PyObject *self, PyObject *args, PyObject *kw)
       str_obj = gdbpy_create_lazy_string_object (value_address (value), length,
 						 user_encoding,
 						 value_type (value));
-
-      do_cleanups (cleanup);
     }
   CATCH (except, RETURN_MASK_ALL)
     {
@@ -514,7 +502,7 @@ valpy_do_cast (PyObject *self, PyObject *args, enum exp_opcode op)
     {
       struct value *val = ((value_object *) self)->value;
       struct value *res_val;
-      struct cleanup *cleanup = make_cleanup_value_free_to_mark (value_mark ());
+      scoped_value_mark free_values;
 
       if (op == UNOP_DYNAMIC_CAST)
 	res_val = value_dynamic_cast (type, val);
@@ -527,7 +515,6 @@ valpy_do_cast (PyObject *self, PyObject *args, enum exp_opcode op)
 	}
 
       result = value_to_value_object (res_val);
-      do_cleanups (cleanup);
     }
   CATCH (except, RETURN_MASK_ALL)
     {
@@ -737,8 +724,8 @@ valpy_getitem (PyObject *self, PyObject *key)
   TRY
     {
       struct value *tmp = self_value->value;
-      struct cleanup *cleanup = make_cleanup_value_free_to_mark (value_mark ());
       struct value *res_val = NULL;
+      scoped_value_mark free_values;
 
       if (field)
 	res_val = value_struct_elt (&tmp, NULL, field.get (), NULL,
@@ -783,7 +770,6 @@ valpy_getitem (PyObject *self, PyObject *key)
 
       if (res_val)
 	result = value_to_value_object (res_val);
-      do_cleanups (cleanup);
     }
   CATCH (ex, RETURN_MASK_ALL)
     {
@@ -861,12 +847,11 @@ valpy_call (PyObject *self, PyObject *args, PyObject *keywords)
 
   TRY
     {
-      struct cleanup *cleanup = make_cleanup_value_free_to_mark (mark);
+      scoped_value_mark free_values;
       struct value *return_value;
 
       return_value = call_function_by_hand (function, args_count, vargs);
       result = value_to_value_object (return_value);
-      do_cleanups (cleanup);
     }
   CATCH (except, RETURN_MASK_ALL)
     {
@@ -1014,11 +999,12 @@ valpy_binop_throw (enum valpy_opcode opcode, PyObject *self, PyObject *other)
   PyObject *result = NULL;
 
   struct value *arg1, *arg2;
-  struct cleanup *cleanup = make_cleanup_value_free_to_mark (value_mark ());
   struct value *res_val = NULL;
   enum exp_opcode op = OP_NULL;
   int handled = 0;
 
+  scoped_value_mark free_values;
+
   /* If the gdb.Value object is the second operand, then it will be
      passed to us as the OTHER argument, and SELF will be an entirely
      different kind of object, altogether.  Because of this, we can't
@@ -1026,17 +1012,11 @@ valpy_binop_throw (enum valpy_opcode opcode, PyObject *self, PyObject *other)
      python as well.  */
   arg1 = convert_value_from_python (self);
   if (arg1 == NULL)
-    {
-      do_cleanups (cleanup);
-      return NULL;
-    }
+    return NULL;
 
   arg2 = convert_value_from_python (other);
   if (arg2 == NULL)
-    {
-      do_cleanups (cleanup);
-      return NULL;
-    }
+    return NULL;
 
   switch (opcode)
     {
@@ -1130,7 +1110,6 @@ valpy_binop_throw (enum valpy_opcode opcode, PyObject *self, PyObject *other)
   if (res_val)
     result = value_to_value_object (res_val);
 
-  do_cleanups (cleanup);
   return result;
 }
 
@@ -1209,12 +1188,11 @@ valpy_negative (PyObject *self)
   TRY
     {
       /* Perhaps overkill, but consistency has some virtue.  */
-      struct cleanup *cleanup = make_cleanup_value_free_to_mark (value_mark ());
+      scoped_value_mark free_values;
       struct value *val;
 
       val = value_neg (((value_object *) self)->value);
       result = value_to_value_object (val);
-      do_cleanups (cleanup);
     }
   CATCH (except, RETURN_MASK_ALL)
     {
@@ -1239,12 +1217,10 @@ valpy_absolute (PyObject *self)
 
   TRY
     {
-      struct cleanup *cleanup = make_cleanup_value_free_to_mark (value_mark ());
+      scoped_value_mark free_values;
 
       if (value_less (value, value_zero (value_type (value), not_lval)))
 	isabs = 0;
-
-      do_cleanups (cleanup);
     }
   CATCH (except, RETURN_MASK_ALL)
     {
@@ -1362,15 +1338,14 @@ valpy_richcompare_throw (PyObject *self, PyObject *other, int op)
   int result;
   struct value *value_other;
   struct value *value_self;
-  struct value *mark = value_mark ();
   struct cleanup *cleanup;
 
+  scoped_value_mark free_values;
+
   value_other = convert_value_from_python (other);
   if (value_other == NULL)
     return -1;
 
-  cleanup = make_cleanup_value_free_to_mark (mark);
-
   value_self = ((value_object *) self)->value;
 
   switch (op)
@@ -1403,7 +1378,6 @@ valpy_richcompare_throw (PyObject *self, PyObject *other, int op)
       break;
     }
 
-  do_cleanups (cleanup);
   return result;
 }