Remove skeleton type units that were being produced with -gsplit-dwarf.

These sections were originally intended as targets for .gdb_index
entries that needed to point to type units.  Because of the limitations
of the .debug_gnu_pubnames/pubtypes sections with split DWARF, we were
not able to pass along enough information to the gold linker to generate
those index entries properly, and they had to point to the CU instead.
GDB had to deal with that, and was updated a while ago to no longer
depend on the skeleton TU sections at all. This allows us to reduce
object file sizes with split DWARF by about 30%.

gcc/
	* dwarf2out.c (get_skeleton_type_unit): Remove.
	(output_skeleton_debug_sections): Remove skeleton type units.
	(output_comdat_type_unit): Likewise.
	(dwarf2out_finish): Likewise.

From-SVN: r213765

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 7519b766ad1386bee0799d0c0e45b71df7a6d569..4be17717d74f028516b870d9e92a4cddc6716f88 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2014-08-08  Cary Coutant  <ccoutant@google.com>
+
+       * dwarf2out.c (get_skeleton_type_unit): Remove.
+       (output_skeleton_debug_sections): Remove skeleton type units.
+       (output_comdat_type_unit): Likewise.
+       (dwarf2out_finish): Likewise.
+
 2014-08-07  Yi Yang  <ahyangyi@google.com>
 
        * predict.c (expr_expected_value_1): Remove the redundant assignment.

diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c
index f90329b00cf1af9cd4b4c4367b38592038cc9119..c1aaa8a87f86266a5f39c56732b5b4d5c9bdc13c 100644 (file)
--- a/gcc/dwarf2out.c
+++ b/gcc/dwarf2out.c
@@ -9069,26 +9069,6 @@ add_top_level_skeleton_die_attrs (dw_die_ref die)
   add_AT_lineptr (die, DW_AT_GNU_addr_base, debug_addr_section_label);
 }
 
-/* Return the single type-unit die for skeleton type units.  */
-
-static dw_die_ref
-get_skeleton_type_unit (void)
-{
-  /* For dwarf_split_debug_sections with use_type info, all type units in the
-     skeleton sections have identical dies (but different headers).  This
-     single die will be output many times.  */
-
-  static dw_die_ref skeleton_type_unit = NULL;
-
-  if (skeleton_type_unit == NULL)
-    {
-      skeleton_type_unit = new_die (DW_TAG_type_unit, NULL, NULL);
-      add_top_level_skeleton_die_attrs (skeleton_type_unit);
-      skeleton_type_unit->die_abbrev = SKELETON_TYPE_DIE_ABBREV;
-    }
-  return skeleton_type_unit;
-}
-
 /* Output skeleton debug sections that point to the dwo file.  */
 
 static void
@@ -9127,8 +9107,6 @@ output_skeleton_debug_sections (dw_die_ref comp_unit)
   ASM_OUTPUT_LABEL (asm_out_file, debug_skeleton_abbrev_section_label);
 
   output_die_abbrevs (SKELETON_COMP_DIE_ABBREV, comp_unit);
-  if (use_debug_types)
-    output_die_abbrevs (SKELETON_TYPE_DIE_ABBREV, get_skeleton_type_unit ());
 
   dw2_asm_output_data (1, 0, "end of skeleton .debug_abbrev");
 }
@@ -9190,38 +9168,6 @@ output_comdat_type_unit (comdat_type_node *node)
   output_die (node->root_die);
 
   unmark_dies (node->root_die);
-
-#if defined (OBJECT_FORMAT_ELF)
-  if (dwarf_split_debug_info)
-    {
-      /* Produce the skeleton type-unit header.  */
-      const char *secname = ".debug_types";
-
-      targetm.asm_out.named_section (secname,
-                                     SECTION_DEBUG | SECTION_LINKONCE,
-                                     comdat_key);
-      if (DWARF_INITIAL_LENGTH_SIZE - DWARF_OFFSET_SIZE == 4)
-        dw2_asm_output_data (4, 0xffffffff,
-          "Initial length escape value indicating 64-bit DWARF extension");
-
-      dw2_asm_output_data (DWARF_OFFSET_SIZE,
-                           DWARF_COMPILE_UNIT_HEADER_SIZE
-                           - DWARF_INITIAL_LENGTH_SIZE
-                           + size_of_die (get_skeleton_type_unit ())
-                           + DWARF_TYPE_SIGNATURE_SIZE + DWARF_OFFSET_SIZE,
-                           "Length of Type Unit Info");
-      dw2_asm_output_data (2, dwarf_version, "DWARF version number");
-      dw2_asm_output_offset (DWARF_OFFSET_SIZE,
-                             debug_skeleton_abbrev_section_label,
-                             debug_abbrev_section,
-                             "Offset Into Abbrev. Section");
-      dw2_asm_output_data (1, DWARF2_ADDR_SIZE, "Pointer Size (in bytes)");
-      output_signature (node->signature, "Type Signature");
-      dw2_asm_output_data (DWARF_OFFSET_SIZE, 0, "Offset to Type DIE");
-
-      output_die (get_skeleton_type_unit ());
-    }
-#endif
 }
 
 /* Return the DWARF2/3 pubname associated with a decl.  */
@@ -24430,7 +24376,6 @@ dwarf2out_finish (const char *filename)
          skeleton die attrs are added when the skeleton type unit is
          created, so ensure it is created by this point.  */
       add_top_level_skeleton_die_attrs (main_comp_unit_die);
-      (void) get_skeleton_type_unit ();
       htab_traverse_noresize (debug_str_hash, index_string, &index);
     }