diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index cb04eb19beb..281d39ad271 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -2415,18 +2415,36 @@ dwarf2_per_objfile::get_tu (int index)
   return this->all_type_units[index];
 }
 
+/* See read.h.  */
+
+dwarf2_per_cu_data *
+dwarf2_per_objfile::allocate_per_cu ()
+{
+  dwarf2_per_cu_data *result = OBSTACK_ZALLOC (&obstack, dwarf2_per_cu_data);
+  result->index = num_psymtabs++;
+  return result;
+}
+
+/* See read.h.  */
+
+signatured_type *
+dwarf2_per_objfile::allocate_signatured_type ()
+{
+  signatured_type *result = OBSTACK_ZALLOC (&obstack, signatured_type);
+  result->per_cu.index = num_psymtabs++;
+  return result;
+}
+
 /* Return a new dwarf2_per_cu_data allocated on the dwarf2_per_objfile
    obstack, and constructed with the specified field values.  */
 
 static dwarf2_per_cu_data *
 create_cu_from_index_list (struct dwarf2_per_objfile *dwarf2_per_objfile,
-                          struct dwarf2_section_info *section,
-                          int is_dwz,
-                          sect_offset sect_off, ULONGEST length)
+			   struct dwarf2_section_info *section,
+			   int is_dwz,
+			   sect_offset sect_off, ULONGEST length)
 {
-  dwarf2_per_cu_data *the_cu
-    = OBSTACK_ZALLOC (&dwarf2_per_objfile->obstack,
-                     struct dwarf2_per_cu_data);
+  dwarf2_per_cu_data *the_cu = dwarf2_per_objfile->allocate_per_cu ();
   the_cu->sect_off = sect_off;
   the_cu->length = length;
   the_cu->dwarf2_per_objfile = dwarf2_per_objfile;
@@ -2517,8 +2535,7 @@ create_signatured_type_table_from_index
       signature = extract_unsigned_integer (bytes + 16, 8, BFD_ENDIAN_LITTLE);
       bytes += 3 * 8;
 
-      sig_type = OBSTACK_ZALLOC (&dwarf2_per_objfile->obstack,
-				 struct signatured_type);
+      sig_type = dwarf2_per_objfile->allocate_signatured_type ();
       sig_type->signature = signature;
       sig_type->type_offset_in_tu = type_offset_in_tu;
       sig_type->per_cu.is_debug_types = 1;
@@ -2574,8 +2591,7 @@ create_signatured_type_table_from_debug_names
 				     section->buffer + to_underlying (sect_off),
 				     rcuh_kind::TYPE);
 
-      sig_type = OBSTACK_ZALLOC (&dwarf2_per_objfile->obstack,
-				 struct signatured_type);
+      sig_type = dwarf2_per_objfile->allocate_signatured_type ();
       sig_type->signature = cu_header.signature;
       sig_type->type_offset_in_tu = cu_header.type_cu_offset_in_tu;
       sig_type->per_cu.is_debug_types = 1;
@@ -6091,8 +6107,7 @@ create_debug_type_hash_table (struct dwarf2_per_objfile *dwarf2_per_objfile,
 	  /* N.B.: type_offset is not usable if this type uses a DWO file.
 	     The real type_offset is in the DWO file.  */
 	  dwo_tu = NULL;
-	  sig_type = OBSTACK_ZALLOC (&dwarf2_per_objfile->obstack,
-				     struct signatured_type);
+	  sig_type = dwarf2_per_objfile->allocate_signatured_type ();
 	  sig_type->signature = header.signature;
 	  sig_type->type_offset_in_tu = header.type_cu_offset_in_tu;
 	  sig_type->per_cu.dwarf2_per_objfile = dwarf2_per_objfile;
@@ -6207,8 +6222,7 @@ add_type_unit (struct dwarf2_per_objfile *dwarf2_per_objfile, ULONGEST sig,
       == dwarf2_per_objfile->all_type_units.capacity ())
     ++dwarf2_per_objfile->tu_stats.nr_all_type_units_reallocs;
 
-  signatured_type *sig_type = OBSTACK_ZALLOC (&dwarf2_per_objfile->obstack,
-					      struct signatured_type);
+  signatured_type *sig_type = dwarf2_per_objfile->allocate_signatured_type ();
 
   dwarf2_per_objfile->all_type_units.push_back (sig_type);
   sig_type->signature = sig;
@@ -7835,16 +7849,10 @@ read_comp_units_from_section (struct dwarf2_per_objfile *dwarf2_per_objfile,
 
       /* Save the compilation unit for later lookup.  */
       if (cu_header.unit_type != DW_UT_type)
-	{
-	  this_cu = XOBNEW (&dwarf2_per_objfile->obstack,
-			    struct dwarf2_per_cu_data);
-	  memset (this_cu, 0, sizeof (*this_cu));
-	}
+	this_cu = dwarf2_per_objfile->allocate_per_cu ();
       else
 	{
-	  auto sig_type = XOBNEW (&dwarf2_per_objfile->obstack,
-				  struct signatured_type);
-	  memset (sig_type, 0, sizeof (*sig_type));
+	  auto sig_type = dwarf2_per_objfile->allocate_signatured_type ();
 	  sig_type->signature = cu_header.signature;
 	  sig_type->type_offset_in_tu = cu_header.type_cu_offset_in_tu;
 	  this_cu = &sig_type->per_cu;
diff --git a/gdb/dwarf2/read.h b/gdb/dwarf2/read.h
index 06a0fa3a19a..5fc7f7f72e5 100644
--- a/gdb/dwarf2/read.h
+++ b/gdb/dwarf2/read.h
@@ -128,6 +128,17 @@ struct dwarf2_per_objfile
 
   /* Free all cached compilation units.  */
   void free_cached_comp_units ();
+
+  /* A convenience function to allocate a dwarf2_per_cu_data (or
+     object holding one, using C-style derivation).  The returned
+     object has its "index" field set properly.  The object is
+     allocated on the dwarf2_per_objfile obstack.  FIXME the index
+     here is weird since it may not (!?!?) be the same as the other
+     index  */
+  dwarf2_per_cu_data *allocate_per_cu ();
+
+  signatured_type *allocate_signatured_type ();
+
 private:
   /* This function is mapped across the sections and remembers the
      offset and size of each of the debugging sections we are
@@ -255,6 +266,10 @@ public:
   /* CUs that are queued to be read.  */
   std::queue<dwarf2_queue_item> queue;
 
+  /* The total number of per_cu and signatured_type objects that have
+     been created for this reader.  */
+  size_t num_psymtabs = 0;
+
   /* State that cannot be shared across objfiles.  This is normally
      nullptr and is temporarily set to the correct value at the entry
      points of the reader.  */
@@ -336,6 +351,9 @@ struct dwarf2_per_cu_data
      This flag is only valid if is_debug_types is true.  */
   unsigned int tu_read : 1;
 
+  /* Our index in the unshared "all_cutus" vector.  */
+  unsigned index;
+
   /* The section this CU/TU lives in.
      If the DIE refers to a DWO file, this is always the original die,
      not the DWO file.  */
