diff mbox

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

Message ID 20140808203445.AB8EF160B77@ccoutant.mtv.corp.google.com
State New
Headers show

Commit Message

Cary Coutant Aug. 8, 2014, 8:34 p.m. UTC 
This patch removes 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%.

I've run both GCC and GDB tests, and found no new regressions.

Committed as r213765.

-cary


2014-08-08  Cary Coutant  <ccoutant@google.com>

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

Patch

Index: gcc/dwarf2out.c
===================================================================
--- gcc/dwarf2out.c	(revision 213764)
+++ gcc/dwarf2out.c	(working copy)
@@ -9069,26 +9069,6 @@  add_top_level_skeleton_die_attrs (dw_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_r
   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_nod
   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);
     }