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, 2 insertions, 6 deletions

diff --git a/gdb/dwarf2loc.c b/gdb/dwarf2loc.c
index e9b41a1..633a459 100644
--- a/gdb/dwarf2loc.c
+++ b/gdb/dwarf2loc.c
@@ -2790,16 +2790,14 @@ dwarf2_loc_desc_get_symbol_read_needs (const gdb_byte *data, size_t size,
 				       struct dwarf2_per_cu_data *per_cu)
 {
   int in_reg;
-  struct cleanup *old_chain;
   struct objfile *objfile = dwarf2_per_cu_objfile (per_cu);
 
+  scoped_value_mark free_values;
+
   symbol_needs_eval_context ctx;
 
   ctx.needs = SYMBOL_NEEDS_NONE;
   ctx.per_cu = per_cu;
-
-  old_chain = make_cleanup_value_free_to_mark (value_mark ());
-
   ctx.gdbarch = get_objfile_arch (objfile);
   ctx.addr_size = dwarf2_per_cu_addr_size (per_cu);
   ctx.ref_addr_size = dwarf2_per_cu_ref_addr_size (per_cu);
@@ -2820,8 +2818,6 @@ dwarf2_loc_desc_get_symbol_read_needs (const gdb_byte *data, size_t size,
           in_reg = 1;
     }
 
-  do_cleanups (old_chain);
-
   if (in_reg)
     ctx.needs = SYMBOL_NEEDS_FRAME;
   return ctx.needs;