gdb/

	Fix crash if referenced CU is aged out.
	* dwarf2loc.c (per_cu_dwarf_call): New variable back_to, use to for
	xfree of block.data.
	(indirect_pieced_value): New variable back_to, use to for xfree of
	baton.data.
	(dwarf2_compile_expr_to_ax): New variable back_to, use to for xfree of
	block.data.
	* dwarf2read.c (dwarf2_find_base_address): New prototype.
	(load_cu): New function from ...
	(dw2_do_instantiate_symtab): ... the code here ...
	(process_full_comp_unit): ... and here.
	(dwarf2_fetch_die_location_block): Call load_cu first.  Call xmemdup on
	retval.data.

gdb/testsuite/
	Fix crash if referenced CU is aged out.
	* gdb.dwarf2/dw2-op-call.exp (maintenance set dwarf2 max-cache-age 0):
	New.
	* gdb.dwarf2/implptr.exp: Likewise.

1 files changed, 34 insertions, 8 deletions

diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c
index da82a2e..a84d356 100644
--- a/gdb/dwarf2read.c
+++ b/gdb/dwarf2read.c
@@ -884,6 +884,9 @@ static void dwarf2_locate_sections (bfd *, asection *, void *);
 static void dwarf2_create_include_psymtab (char *, struct partial_symtab *,
                                            struct objfile *);
 
+static void dwarf2_find_base_address (struct die_info *die,
+				      struct dwarf2_cu *cu);
+
 static void dwarf2_build_psymtabs_hard (struct objfile *);
 
 static void scan_partial_symbols (struct partial_die_info *,
@@ -1788,6 +1791,23 @@ create_quick_file_names_table (unsigned int nr_initial_entries)
 			    delete_file_name_entry, xcalloc, xfree);
 }
 
+/* Read in PER_CU->CU.  This function is unrelated to symtabs, symtab would
+   have to be created afterwards.  You should call age_cached_comp_units after
+   processing PER_CU->CU.  dw2_setup must have been already called.  */
+
+static void
+load_cu (struct dwarf2_per_cu_data *per_cu)
+{
+  if (per_cu->from_debug_types)
+    read_signatured_type_at_offset (per_cu->objfile, per_cu->offset);
+  else
+    load_full_comp_unit (per_cu, per_cu->objfile);
+
+  dwarf2_find_base_address (per_cu->cu->dies, per_cu->cu);
+
+  gdb_assert (per_cu->cu != NULL);
+}
+
 /* Read in the symbols for PER_CU.  OBJFILE is the objfile from which
    this CU came.  */
 
@@ -1801,10 +1821,7 @@ dw2_do_instantiate_symtab (struct objfile *objfile,
 
   queue_comp_unit (per_cu, objfile);
 
-  if (per_cu->from_debug_types)
-    read_signatured_type_at_offset (objfile, per_cu->offset);
-  else
-    load_full_comp_unit (per_cu, objfile);
+  load_cu (per_cu);
 
   process_queue (objfile);
 
@@ -4714,8 +4731,6 @@ process_full_comp_unit (struct dwarf2_per_cu_data *per_cu)
 
   cu->list_in_scope = &file_symbols;
 
-  dwarf2_find_base_address (cu->dies, cu);
-
   /* Do line number decoding in read_file_scope () */
   process_die (cu->dies, cu);
 
@@ -13813,7 +13828,8 @@ follow_die_ref (struct die_info *src_die, struct attribute *attr,
 }
 
 /* Return DWARF block and its CU referenced by OFFSET at PER_CU.  Returned
-   value is intended for DW_OP_call*.  */
+   value is intended for DW_OP_call*.  You must call xfree on returned
+   dwarf2_locexpr_baton->data.  */
 
 struct dwarf2_locexpr_baton
 dwarf2_fetch_die_location_block (unsigned int offset,
@@ -13821,13 +13837,17 @@ dwarf2_fetch_die_location_block (unsigned int offset,
 				 CORE_ADDR (*get_frame_pc) (void *baton),
 				 void *baton)
 {
-  struct dwarf2_cu *cu = per_cu->cu;
+  struct dwarf2_cu *cu;
   struct die_info *die;
   struct attribute *attr;
   struct dwarf2_locexpr_baton retval;
 
   dw2_setup (per_cu->objfile);
 
+  if (per_cu->cu == NULL)
+    load_cu (per_cu);
+  cu = per_cu->cu;
+
   die = follow_die_offset (offset, &cu);
   if (!die)
     error (_("Dwarf Error: Cannot find DIE at 0x%x referenced in module %s"),
@@ -13864,6 +13884,12 @@ dwarf2_fetch_die_location_block (unsigned int offset,
       retval.size = DW_BLOCK (attr)->size;
     }
   retval.per_cu = cu->per_cu;
+
+  if (retval.data)
+    retval.data = xmemdup (retval.data, retval.size, retval.size);
+
+  age_cached_comp_units ();
+
   return retval;
 }