[PATCH 09/14] Add objfile member to DWARF batons

[Tom Tromey <tom@tromey.com>]

Various DWARF callbacks expect to be able to fetch the objfile from
the DWARF CU object.  However, this won't be possible once sharing is
implemented.

Because these objects are related to full symbols (e.g., they are used
to implement location expressions), they can simply store the objfile
they need.

This patch adds an objfile member to the various "baton" structures
and arranges to set this value when constructing the baton.

gdb/ChangeLog
2020-02-15  Tom Tromey  <tom@tromey.com>

	* dwarf2/loc.c (struct piece_closure) <objfile>: New member.
	(allocate_piece_closure): Set "objfile" member.
	* dwarf2/read.c (read_call_site_scope)
	(mark_common_block_symbol_computed, attr_to_dynamic_prop)
	(dwarf2_const_value_attr, dwarf2_fetch_die_loc_sect_off)
	(fill_in_loclist_baton, dwarf2_symbol_mark_computed): Set objfile
	member.
	* dwarf2/loc.h (struct dwarf2_locexpr_baton) <objfile>: New
	member.
	(struct dwarf2_loclist_baton) <objfile>: New member.
---
 gdb/ChangeLog     | 13 +++++++++++++
 gdb/dwarf2/loc.c  |  5 +++++
 gdb/dwarf2/loc.h  |  6 ++++++
 gdb/dwarf2/read.c | 12 ++++++++++--
 4 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/gdb/dwarf2/loc.c b/gdb/dwarf2/loc.c
index a9523e9f7ee..4a148c26722 100644
--- a/gdb/dwarf2/loc.c
+++ b/gdb/dwarf2/loc.c
@@ -1544,6 +1544,9 @@ struct piece_closure
   /* Reference count.  */
   int refc = 0;
 
+  /* The objfile from which this closure's expression came.  */
+  struct objfile *objfile = nullptr;
+
   /* The CU from which this closure's expression came.  */
   struct dwarf2_per_cu_data *per_cu = NULL;
 
@@ -1566,6 +1569,8 @@ allocate_piece_closure (struct dwarf2_per_cu_data *per_cu,
   struct piece_closure *c = new piece_closure;
 
   c->refc = 1;
+  /* We must capture this here due to sharing of DWARF state.  */
+  c->objfile = per_cu->objfile ();
   c->per_cu = per_cu;
   c->pieces = std::move (pieces);
   if (frame == NULL)
diff --git a/gdb/dwarf2/loc.h b/gdb/dwarf2/loc.h
index 8fff663ebf9..51bcf6158a8 100644
--- a/gdb/dwarf2/loc.h
+++ b/gdb/dwarf2/loc.h
@@ -166,6 +166,9 @@ struct dwarf2_locexpr_baton
      directly.  */
   bool is_reference;
 
+  /* The objfile that was used when creating this.  */
+  struct objfile *objfile;
+
   /* The compilation unit containing the symbol whose location
      we're computing.  */
   struct dwarf2_per_cu_data *per_cu;
@@ -183,6 +186,9 @@ struct dwarf2_loclist_baton
   /* Length of the location list.  */
   size_t size;
 
+  /* The objfile that was used when creating this.  */
+  struct objfile *objfile;
+
   /* The compilation unit containing the symbol whose location
      we're computing.  */
   struct dwarf2_per_cu_data *per_cu;
diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index 44fdb070e49..7b493f5a227 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -13298,6 +13298,7 @@ read_call_site_scope (struct die_info *die, struct dwarf2_cu *cu)
       dlbaton = XOBNEW (&objfile->objfile_obstack, struct dwarf2_locexpr_baton);
       dlbaton->data = DW_BLOCK (attr)->data;
       dlbaton->size = DW_BLOCK (attr)->size;
+      dlbaton->objfile = objfile;
       dlbaton->per_cu = cu->per_cu;
 
       SET_FIELD_DWARF_BLOCK (call_site->target, dlbaton);
@@ -16018,6 +16019,7 @@ mark_common_block_symbol_computed (struct symbol *sym,
 	      || member_loc->form_is_constant ());
 
   baton = XOBNEW (&objfile->objfile_obstack, struct dwarf2_locexpr_baton);
+  baton->objfile = objfile;
   baton->per_cu = cu->per_cu;
   gdb_assert (baton->per_cu);
 
@@ -17119,8 +17121,8 @@ attr_to_dynamic_prop (const struct attribute *attr, struct die_info *die,
 		      struct type *default_type)
 {
   struct dwarf2_property_baton *baton;
-  struct obstack *obstack
-    = &cu->per_cu->dwarf2_per_objfile->objfile->objfile_obstack;
+  struct objfile *objfile = cu->per_cu->dwarf2_per_objfile->objfile;
+  struct obstack *obstack = &objfile->objfile_obstack;
 
   gdb_assert (default_type != NULL);
 
@@ -17132,6 +17134,7 @@ attr_to_dynamic_prop (const struct attribute *attr, struct die_info *die,
       baton = XOBNEW (obstack, struct dwarf2_property_baton);
       baton->property_type = default_type;
       baton->locexpr.per_cu = cu->per_cu;
+      baton->locexpr.objfile = objfile;
       baton->locexpr.size = DW_BLOCK (attr)->size;
       baton->locexpr.data = DW_BLOCK (attr)->data;
       switch (attr->name)
@@ -17178,6 +17181,7 @@ attr_to_dynamic_prop (const struct attribute *attr, struct die_info *die,
 		baton = XOBNEW (obstack, struct dwarf2_property_baton);
 		baton->property_type = die_type (target_die, target_cu);
 		baton->locexpr.per_cu = cu->per_cu;
+		baton->locexpr.objfile = objfile;
 		baton->locexpr.size = DW_BLOCK (target_attr)->size;
 		baton->locexpr.data = DW_BLOCK (target_attr)->data;
 		baton->locexpr.is_reference = true;
@@ -21037,6 +21041,7 @@ dwarf2_const_value_attr (const struct attribute *attr, struct type *type,
 	   piggyback on the existing location code rather than writing
 	   a new implementation of symbol_computed_ops.  */
 	*baton = XOBNEW (obstack, struct dwarf2_locexpr_baton);
+	(*baton)->objfile = objfile;
 	(*baton)->per_cu = cu->per_cu;
 	gdb_assert ((*baton)->per_cu);
 
@@ -22411,6 +22416,7 @@ dwarf2_fetch_die_loc_sect_off (sect_offset sect_off,
       retval.data = DW_BLOCK (attr)->data;
       retval.size = DW_BLOCK (attr)->size;
     }
+  retval.objfile = objfile;
   retval.per_cu = cu->per_cu;
 
   age_cached_comp_units (dwarf2_per_objfile);
@@ -24051,6 +24057,7 @@ fill_in_loclist_baton (struct dwarf2_cu *cu,
 
   section->read (dwarf2_per_objfile->objfile);
 
+  baton->objfile = dwarf2_per_objfile->objfile;
   baton->per_cu = cu->per_cu;
   gdb_assert (baton->per_cu);
   /* We don't know how long the location list is, but make sure we
@@ -24096,6 +24103,7 @@ dwarf2_symbol_mark_computed (const struct attribute *attr, struct symbol *sym,
       struct dwarf2_locexpr_baton *baton;
 
       baton = XOBNEW (&objfile->objfile_obstack, struct dwarf2_locexpr_baton);
+      baton->objfile = objfile;
       baton->per_cu = cu->per_cu;
       gdb_assert (baton->per_cu);
 
-- 
2.17.2