[PATCH 13/14] Move signatured_type::type to unshareable object

[Tom Tromey]

signatured_type has a link to the "struct type".  However, types are
inherently objfile-specific, so once sharing is implemented, this will
be incorrect.

This patch moves the type to a new map in the DWARF unshareable
object.

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

	* dwarf2/read.h (struct dwarf2_unshareable) <type_map>: New
	member.
	(struct signatured_type) <type>: Remove.
	* dwarf2/read.c (get_signatured_type): Use type_map.
---
 gdb/ChangeLog     | 7 +++++++
 gdb/dwarf2/read.c | 7 ++++---
 gdb/dwarf2/read.h | 8 +++-----
 3 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index 765fc4e8272..15813b72005 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -22767,8 +22767,9 @@ get_signatured_type (struct die_info *die, ULONGEST signature,
     }
 
   /* If we already know the type we're done.  */
-  if (sig_type->type != NULL)
-    return sig_type->type;
+  auto iter = dwarf2_per_objfile->unshareable->type_map.find (sig_type);
+  if (iter != dwarf2_per_objfile->unshareable->type_map.end ())
+    return iter->second;
 
   type_cu = cu;
   type_die = follow_die_sig_1 (die, sig_type, &type_cu);
@@ -22795,7 +22796,7 @@ get_signatured_type (struct die_info *die, ULONGEST signature,
 		 objfile_name (dwarf2_per_objfile->objfile));
       type = build_error_marker_type (cu, die);
     }
-  sig_type->type = type;
+  dwarf2_per_objfile->unshareable->type_map[sig_type] = type;
 
   return type;
 }
diff --git a/gdb/dwarf2/read.h b/gdb/dwarf2/read.h
index 18f3c264a0a..241f3c8e71e 100644
--- a/gdb/dwarf2/read.h
+++ b/gdb/dwarf2/read.h
@@ -112,6 +112,9 @@ struct dwarf2_unshareable
      structure.  */
   std::unordered_map<type_unit_group *, std::unique_ptr<type_unit_unshareable>>
     type_units;
+
+  /* Map from signatured types to the corresponding struct type.  */
+  std::unordered_map<signatured_type *, struct type *> type_map;
 };
 
 /* Collection of data recorded per objfile.
@@ -574,11 +577,6 @@ struct signatured_type
      can share them.  This points to the containing symtab.  */
   struct type_unit_group *type_unit_group;
 
-  /* The type.
-     The first time we encounter this type we fully read it in and install it
-     in the symbol tables.  Subsequent times we only need the type.  */
-  struct type *type;
-
   /* Containing DWO unit.
      This field is valid iff per_cu.reading_dwo_directly.  */
   struct dwo_unit *dwo_unit;
-- 
2.17.2