Patchwork [google/gcc-4_7] Backport pending Fission patch (issue6443043)

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Submitter Cary Coutant
Date July 25, 2012, 12:08 a.m.
Message ID <20120725000844.6CCD9E0F80@ccoutant.mtv.corp.google.com>
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Permalink /patch/173083/
State New
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Cary Coutant - July 25, 2012, 12:08 a.m.
This patch is for the google/gcc-4_7 branch.

Backport Fission patches from trunk at r186934, r187061, and r188759.
Backport pending Fission patch at http://codereview.appspot.com/6305113.
    
Patches for include/dwarf2.def have been backported to include/dwarf2.h.

Tested by bootstrap and regression testing.

    
    2012-07-18  Sterling Augustine <saugustine@google.com>
                Cary Coutant <ccoutant@google.com>
    
    include/
    	* dwarf2.h (dwarf_location_list_entry_type): New enum with enumerators
    	DW_LLE_end_of_list_entry, DW_LLE_base_address_selection_entry,
    	DW_LLE_start_end_entry, DW_LLE_start_length_entry.
    
    gcc/
    	* common.opt (gno-split-dwarf, gsplit-dwarf): New switches.
    	* doc/invoke.texi (Debugging Options): Document them.
    	* opts.c (finish_options): Make gsplit-dwarf imply -gpubnames.
    	* dwarf2out.h (dw_val_struct): New field val_index.
    	* dwarf2out.c (debug_skeleton_info_section,
    	debug_skeleton_abbrev_section, debug_addr_section,
    	debug_skeleton_line_section, debug_str_offsets_section): New sections.
    	(indirect_string_node): Add index field.
    	(dw_loc_list_node): Add begin_index field.
    	(dw_addr_op, new_addr_loc_descr, AT_index, set_AT_index,
    	add_addr_table_entry, remove_addr_table_entry, output_range_list_offset,
    	output_loc_list_offset, output_attr_index_or_value,
    	remove_loc_list_addr_table_entries, output_die_abbrevs,
    	add_top_level_skeleton_die_attrs, get_skeleton_type_unit,
    	output_skeleton_debug_sections, output_index_strings,
    	output_addr_table, index_location_lists): New functions.
    	(DEBUG_DWO_INFO_SECTION, DEBUG_DWO_ABBREV_SECTION, DEBUG_ADDR_SECTION,
    	DEBUG_NORM_MACINFO_SECTION, DEBUG_DWO_MACINFO_SECTION,
    	DEBUG_DWO_LINE_SECTION, DEBUG_DWO_LOC_SECTION,
    	DEBUG_NORM_STR_OFFSETS_SECTION, DEBUG_DWO_STR_SECTION,
    	DEBUG_MACRO_SECTION_FLAGS, DEBUG_SKELETON_LINE_SECTION_LABEL,
    	DEBUG_SKELETON_INFO_SECTION_LABEL, DEBUG_SKELETON_ABBREV_SECTION_LABEL,
    	DEBUG_ADDR_SECTIN_LABEL, SKELETON_COMP_DIE_ABBREV,
    	SKELETON_TYPE_DIE_ABBREV): New defines.
    	(DEBUG_MACINFO_SECTION, DEBUG_MACRO_SECTION, DEBUG_STR_SECTION
    	DEBUG_STR_SECTION_FLAGS): Adjust definitions.
    	(TEXT_SECTION_LABEL, COLD_TEXT_SECTION_LABEL, DEBUG_INFO_SECTION_LABEL,
    	DEBUG_ABBREV_SECTION_LABEL, DEBUG_LOC_SECTION_LABEL,
    	DEBUG_RANGES_SECTION_LABEL, DEBUG_MACINFO_SECTION_LABEL,
    	DEBUG_MACRO_SECTION_LABEL): Adjust indentation.
    	(debug_skeleton_info_section_label, debug_skeleton_abbrev_section_label,
    	debug_addr_section_label, debug_skeleton_line_section_label,
    	dw_id_placeholder): New	global variables.
    	(add_AT_lbl_id): Add force_direct parameter.  Adjust calls throughout
    	file.  Handle dwarf_split_debug_info.
    	(add_AT_addr). Likewise.  Initialize val_index_field.
    	(add_AT_range_list): Add force parameter.  Adjust calls throughout file.
    	Initialize val_index field.
    	(add_ranges_by_labels): Add and handle force_direct parameter.  Adjust
    	calls throughout file.
    	(size_of_die): New variable form.  Handle dwarf_split_debug_info and
    	call AT_index.
    	(value_format): Use AT_class instead of calling val_class directly.
    	Handle DW_FORM_addr and dw_val_class_lbl_id appropriately for
    	dwarf_split_debug_info and AT_index.
    	(output_abbrev_section): Move most code to new function
    	output_die_abbrevs.
    	(output_loc_list): Handle dwarf_split_debug_info by using
    	DW_LLE_start_length_entry and DW_LLE_end_of_list_entry.
    	(output_die): Call output_attr_index_or_value, output_range_list_offset,
    	Fix format string.  Check val_str->form directly to avoid side effect.
    	(add_pubtype): Fix indention.
    	(output_comdat_type_unit): Handle dwarf_split_debug_info.
    	(output_pubnames): Likewise.
    	(output_aranges): Likewise.
    	(output_mac_info): Likewise.
    	(output_line_info): New parameter prologue_only.  Adjust calls
    	throughout file.
    	(mem_loc_descriptor): Call new_addr_loc_descr.
    	(loc_descriptor): Likewise.
    	(add_const_value_attribute): Likewise.
    	(loc_list_from_tree): Replace first_op and second_op with tls_op.
    	Update associated logic.  Call new_addr_loc_descr.
    	(dwarf2out_init): Handle dwarf_split_debug_info.  Initialize
    	debug_skeleton_info_section, debug_skeleton_abbrev_section,
    	debug_addr_section, debug_skeleton_line_section,
    	debug_str_offsets_section, debug_skeleton_info_section_label,
    	debug_skeleton_abbrev_section_label, debug_addr_section_label and
    	debug_skeleton_line_section_label.  Use DEBUG_MACRO_SECTION_FLAGS.
    	(new_loc_descr, build_cfa_loc, add_AT_flag, add_AT_int, add_AT_unsigned,
    	add_AT_double, add_AT_vec, add_AT_data8, add_AT_string, add_AT_die_ref,
    	add_AT_fde_ref, add_AT_loc, add_AT_loc_list, add_AT_file,
    	add_AT_vms_delta, add_AT_lineptr, add_AT_macptr, add_AT_offset):
    	Initialize val_index field.
    	(size_of_loc_descr, output_loc_operands, output_loc_operands_raw,
    	resolve_addr_in_expression, hash_loc_operands):	Handle
    	DW_OP_GNU_addr_index and DW_OP_GNU_const_index.
    	(compare_loc_operands):  Likewise.  Adjust assertion.
    	(AT_string_form): Handle dwarf_split_debug_info.
    	(resolve_addr): New local variable l.  Check val_index.  Call
    	remove_addr_table_entry and remove_loc_list_addr_table_entries.
    	(dwarf2out_finish): Handle dwarf_split_debug_info.  New variable
    	main_comp_unit_die.  Call index_location_lists, add_AT_data8,
    	add_AT_lineptr, output_skeleton_debug_sections, output_addr_table.  Move
    	call to	ASM_GENERATE_INTERNAL_LABEL to dwarf2out_init.  Call
    	ASM_OUTPUT_LABEL for debug_skeleton_line_section_label and
    	debug_addr_section_label.  Adjust comment.
    	* gcc.c (replace_extension_spec_func):  New function.
    	(ASM_FINAL_SPEC): Adjust.  Fix related comments.
    	(check_live_switch): Likewise.
    
    2012-06-18  Doug Evans  <dje@google.com>
    
            * dwarf2.def (DW_OP): Add DW_OP_GNU_const_index.
    
    2012-05-02  Cary Coutant  <ccoutant@google.com>
    
            * dwarf2.def: Remove DW_FORM_GNU_ref_index,
            replace DW_AT_GNU_ref_base with DW_AT_GNU_ranges_base.
    
    2012-04-28  Doug Evans  <dje@google.com>
    
            * dwarf2.def (DW_OP): Add DW_OP_GNU_addr_index.


--
This patch is available for review at http://codereview.appspot.com/6443043
Cary Coutant - July 25, 2012, 12:34 a.m.
> This is OK for Google 4.7

Thanks, committed at r189833.

-cary
Sterling Augustine - July 25, 2012, 12:42 a.m.
On Tue, Jul 24, 2012 at 5:08 PM, Cary Coutant <ccoutant@google.com> wrote:
> This patch is for the google/gcc-4_7 branch.
>
> Backport Fission patches from trunk at r186934, r187061, and r188759.
> Backport pending Fission patch at http://codereview.appspot.com/6305113.
>
> Patches for include/dwarf2.def have been backported to include/dwarf2.h.

This is OK for google 4.7.

Sterling

Patch

Index: include/dwarf2.h
===================================================================
--- include/dwarf2.h	(revision 189829)
+++ include/dwarf2.h	(working copy)
@@ -190,7 +190,6 @@  enum dwarf_form
     DW_FORM_flag_present = 0x19,
     DW_FORM_ref_sig8 = 0x20,
     /* Extensions for Fission.  See http://gcc.gnu.org/wiki/DebugFission.  */
-    DW_FORM_GNU_ref_index = 0x1f00,
     DW_FORM_GNU_addr_index = 0x1f01,
     DW_FORM_GNU_str_index = 0x1f02
   };
@@ -375,7 +374,7 @@  enum dwarf_attribute
     /* Extensions for Fission.  See http://gcc.gnu.org/wiki/DebugFission.  */
     DW_AT_GNU_dwo_name = 0x2130,
     DW_AT_GNU_dwo_id = 0x2131,
-    DW_AT_GNU_ref_base = 0x2132,
+    DW_AT_GNU_ranges_base = 0x2132,
     DW_AT_GNU_addr_base = 0x2133,
     DW_AT_GNU_pubnames = 0x2134,
     DW_AT_GNU_pubtypes = 0x2135,
@@ -578,6 +577,9 @@  enum dwarf_location_atom
     DW_OP_GNU_reinterpret = 0xf9,
     /* The GNU parameter ref extension.  */
     DW_OP_GNU_parameter_ref = 0xfa,
+    /* Extensions for Fission.  See http://gcc.gnu.org/wiki/DebugFission.  */
+    DW_OP_GNU_addr_index = 0xfb,
+    DW_OP_GNU_const_index = 0xfc,
     /* HP extensions.  */
     DW_OP_HP_unknown     = 0xe0, /* Ouch, the same as GNU_push_tls_address.  */
     DW_OP_HP_is_value    = 0xe1,
@@ -829,6 +831,17 @@  enum dwarf_call_frame_info
     DW_CFA_GNU_negative_offset_extended = 0x2f
   };
 
+/* Type codes for location list entries.
+   Extension for Fission.  See http://gcc.gnu.org/wiki/DebugFission.  */
+
+enum dwarf_location_list_entry_type
+  {
+    DW_LLE_end_of_list_entry = 0,
+    DW_LLE_base_address_selection_entry = 1,
+    DW_LLE_start_end_entry = 2,
+    DW_LLE_start_length_entry = 3
+  };
+
 #define DW_CIE_ID	  0xffffffff
 #define DW64_CIE_ID	  0xffffffffffffffffULL
 #define DW_CIE_VERSION	  1
Index: gcc/doc/invoke.texi
===================================================================
--- gcc/doc/invoke.texi	(revision 189829)
+++ gcc/doc/invoke.texi	(working copy)
@@ -4952,6 +4952,14 @@  it reasonable to use the optimizer for p
 The following options are useful when GCC is generated with the
 capability for more than one debugging format.
 
+@item -gsplit-dwarf
+@opindex gsplit-dwarf
+Separate as much dwarf debugging information as possible into a
+separate output file with the extension .dwo.  This option allows
+the build system to avoid linking files with debug information.  To
+be useful, this option requires a debugger capable of reading .dwo
+files.
+
 @item -ggdb
 @opindex ggdb
 Produce debugging information for use by GDB@.  This means to use the
Index: gcc/gcc.c
===================================================================
--- gcc/gcc.c	(revision 189829)
+++ gcc/gcc.c	(working copy)
@@ -267,6 +267,7 @@  static const char *compare_debug_dump_op
 static const char *compare_debug_self_opt_spec_function (int, const char **);
 static const char *compare_debug_auxbase_opt_spec_function (int, const char **);
 static const char *pass_through_libs_spec_func (int, const char **);
+static const char *replace_extension_spec_func (int, const char **);
 
 /* The Specs Language
 
@@ -446,7 +447,7 @@  ignored.  White space may also appear an
 colon in these constructs, except between . or * and the corresponding
 word.
 
-The -O, -f, -m, and -W switches are handled specifically in these
+The -O, -f, -g, -m, and -W switches are handled specifically in these
 constructs.  If another value of -O or the negated form of a -f, -m, or
 -W switch is found later in the command line, the earlier switch
 value is ignored, except with {S*} where S is just one letter; this
@@ -479,7 +480,14 @@  proper position among the other output f
 /* config.h can define ASM_FINAL_SPEC to run a post processor after
    the assembler has run.  */
 #ifndef ASM_FINAL_SPEC
-#define ASM_FINAL_SPEC ""
+#define ASM_FINAL_SPEC \
+  "%{gsplit-dwarf: \n\
+       objcopy --extract-dwo \
+	 %{c:%{o*:%*}%{!o*:%b%O}}%{!c:%U%O} \
+	 %{c:%{o*:%:replace-extension(%{o*:%*} .dwo)}%{!o*:%b.dwo}}%{!c:%b.dwo} \n\
+       objcopy --strip-dwo \
+	 %{c:%{o*:%*}%{!o*:%b%O}}%{!c:%U%O} \
+    }"
 #endif
 
 /* config.h can define CPP_SPEC to provide extra args to the C preprocessor
@@ -1276,6 +1284,7 @@  static const struct spec_function static
   { "compare-debug-self-opt",	compare_debug_self_opt_spec_function },
   { "compare-debug-auxbase-opt", compare_debug_auxbase_opt_spec_function },
   { "pass-through-libs",	pass_through_libs_spec_func },
+  { "replace-extension",	replace_extension_spec_func },
 #ifdef EXTRA_SPEC_FUNCTIONS
   EXTRA_SPEC_FUNCTIONS
 #endif
@@ -5783,7 +5792,7 @@  process_brace_body (const char *p, const
    on the command line.  PREFIX_LENGTH is the length of XXX in an {XXX*}
    spec, or -1 if either exact match or %* is used.
 
-   A -O switch is obsoleted by a later -O switch.  A -f, -m, or -W switch
+   A -O switch is obsoleted by a later -O switch.  A -f, -g, -m, or -W switch
    whose value does not begin with "no-" is obsoleted by the same value
    with the "no-", similarly for a switch with the "no-" prefix.  */
 
@@ -5820,7 +5829,7 @@  check_live_switch (int switchnum, int pr
 	  }
       break;
 
-    case 'W':  case 'f':  case 'm':
+    case 'W':  case 'f':  case 'm': case 'g':
       if (! strncmp (name + 1, "no-", 3))
 	{
 	  /* We have Xno-YYY, search for XYYY.  */
@@ -8394,3 +8403,27 @@  pass_through_libs_spec_func (int argc, c
     }
   return prepended;
 }
+
+/* %:replace-extension spec function.  Replaces the extension of the
+   first argument with the second argument.  */
+
+const char *
+replace_extension_spec_func (int argc, const char **argv)
+{
+  char *name;
+  char *p;
+  char *result;
+
+  if (argc != 2)
+    fatal_error ("too few arguments to %%:replace-extension");
+
+  name = xstrdup (argv[0]);
+  p = strrchr (name, '.');
+  if (p != NULL)
+      *p = '\0';
+
+  result = concat (name, argv[1], NULL);
+
+  free (name);
+  return result;
+}
Index: gcc/dwarf2out.c
===================================================================
--- gcc/dwarf2out.c	(revision 189829)
+++ gcc/dwarf2out.c	(working copy)
@@ -153,14 +153,19 @@  static GTY(()) VEC(tree,gc) *decl_scope_
 
 /* Pointers to various DWARF2 sections.  */
 static GTY(()) section *debug_info_section;
+static GTY(()) section *debug_skeleton_info_section;
 static GTY(()) section *debug_abbrev_section;
+static GTY(()) section *debug_skeleton_abbrev_section;
 static GTY(()) section *debug_aranges_section;
+static GTY(()) section *debug_addr_section;
 static GTY(()) section *debug_macinfo_section;
 static GTY(()) section *debug_line_section;
+static GTY(()) section *debug_skeleton_line_section;
 static GTY(()) section *debug_loc_section;
 static GTY(()) section *debug_pubnames_section;
 static GTY(()) section *debug_pubtypes_section;
 static GTY(()) section *debug_str_section;
+static GTY(()) section *debug_str_offsets_section;
 static GTY(()) section *debug_ranges_section;
 static GTY(()) section *debug_frame_section;
 
@@ -203,6 +208,7 @@  struct GTY(()) indirect_string_node {
   unsigned int refcount;
   enum dwarf_form form;
   char *label;
+  unsigned int index;
 };
 
 static GTY ((param_is (struct indirect_string_node))) htab_t debug_str_hash;
@@ -1214,7 +1220,8 @@  DEF_VEC_ALLOC_P(dw_die_ref,heap);
    their entire life.  */
 typedef struct GTY(()) dw_loc_list_struct {
   dw_loc_list_ref dw_loc_next;
-  const char *begin; /* Label for begin address of range */
+  const char *begin; /* Label and index for begin address of range */
+  unsigned int begin_index;
   const char *end;  /* Label for end address of range */
   char *ll_symbol; /* Label for beginning of location list.
 		      Only on head of list */
@@ -1591,8 +1598,10 @@  new_loc_descr (enum dwarf_location_atom 
 
   descr->dw_loc_opc = op;
   descr->dw_loc_oprnd1.val_class = dw_val_class_unsigned_const;
+  descr->dw_loc_oprnd1.val_index = -1U;
   descr->dw_loc_oprnd1.v.val_unsigned = oprnd1;
   descr->dw_loc_oprnd2.val_class = dw_val_class_unsigned_const;
+  descr->dw_loc_oprnd2.val_index = -1U;
   descr->dw_loc_oprnd2.v.val_unsigned = oprnd2;
 
   return descr;
@@ -1796,6 +1805,10 @@  size_of_loc_descr (dw_loc_descr_ref loc)
     case DW_OP_addr:
       size += DWARF2_ADDR_SIZE;
       break;
+    case DW_OP_GNU_addr_index:
+    case DW_OP_GNU_const_index:
+      size += size_of_uleb128 (loc->dw_loc_oprnd1.val_index);
+      break;
     case DW_OP_const1u:
     case DW_OP_const1s:
       size += 1;
@@ -2232,6 +2245,12 @@  output_loc_operands (dw_loc_descr_ref lo
 	}
       break;
 
+    case DW_OP_GNU_addr_index:
+    case DW_OP_GNU_const_index:
+      dw2_asm_output_data_uleb128 (loc->dw_loc_oprnd1.val_index,
+                                   "(index into .debug_addr)");
+      break;
+
     case DW_OP_GNU_implicit_pointer:
       {
 	char label[MAX_ARTIFICIAL_LABEL_BYTES
@@ -2407,6 +2426,8 @@  output_loc_operands_raw (dw_loc_descr_re
   switch (loc->dw_loc_opc)
     {
     case DW_OP_addr:
+    case DW_OP_GNU_addr_index:
+    case DW_OP_GNU_const_index:
     case DW_OP_implicit_value:
       /* We cannot output addresses in .cfi_escape, only bytes.  */
       gcc_unreachable ();
@@ -2590,6 +2611,7 @@  build_cfa_loc (dw_cfa_location *cfa, HOS
     {
       head = new_reg_loc_descr (cfa->reg, cfa->base_offset);
       head->dw_loc_oprnd1.val_class = dw_val_class_const;
+      head->dw_loc_oprnd1.val_index = -1U;
       tmp = new_loc_descr (DW_OP_deref, 0, 0);
       add_loc_descr (&head, tmp);
       if (offset != 0)
@@ -3217,6 +3239,8 @@  static tree decl_ultimate_origin (const_
 static tree decl_class_context (tree);
 static void add_dwarf_attr (dw_die_ref, dw_attr_ref);
 static inline enum dw_val_class AT_class (dw_attr_ref);
+static inline unsigned int AT_index (dw_attr_ref);
+static inline void set_AT_index (dw_attr_ref, unsigned int);
 static void add_AT_flag (dw_die_ref, enum dwarf_attribute, unsigned);
 static inline unsigned AT_flag (dw_attr_ref);
 static void add_AT_int (dw_die_ref, enum dwarf_attribute, HOST_WIDE_INT);
@@ -3244,15 +3268,18 @@  static inline dw_loc_descr_ref AT_loc (d
 static void add_AT_loc_list (dw_die_ref, enum dwarf_attribute,
 			     dw_loc_list_ref);
 static inline dw_loc_list_ref AT_loc_list (dw_attr_ref);
-static void add_AT_addr (dw_die_ref, enum dwarf_attribute, rtx);
+static unsigned int add_addr_table_entry (dw_attr_node *);
+static void remove_addr_table_entry (unsigned int);
+static void add_AT_addr (dw_die_ref, enum dwarf_attribute, rtx, bool);
 static inline rtx AT_addr (dw_attr_ref);
-static void add_AT_lbl_id (dw_die_ref, enum dwarf_attribute, const char *);
+static void add_AT_lbl_id (dw_die_ref, enum dwarf_attribute, const char *,
+			   bool);
 static void add_AT_lineptr (dw_die_ref, enum dwarf_attribute, const char *);
 static void add_AT_macptr (dw_die_ref, enum dwarf_attribute, const char *);
 static void add_AT_offset (dw_die_ref, enum dwarf_attribute,
 			   unsigned HOST_WIDE_INT);
 static void add_AT_range_list (dw_die_ref, enum dwarf_attribute,
-			       unsigned long);
+			       unsigned long, bool);
 static inline const char *AT_lbl (dw_attr_ref);
 static dw_attr_ref get_AT (dw_die_ref, enum dwarf_attribute);
 static const char *get_AT_low_pc (dw_die_ref);
@@ -3347,6 +3374,7 @@  static unsigned long size_of_aranges (vo
 static enum dwarf_form value_format (dw_attr_ref);
 static void output_value_format (dw_attr_ref);
 static void output_abbrev_section (void);
+static void output_die_abbrevs (unsigned long, dw_die_ref);
 static void output_die_symbol (dw_die_ref);
 static void output_die (dw_die_ref);
 static void output_compilation_unit_header (void);
@@ -3362,10 +3390,10 @@  static void output_aranges (unsigned lon
 static unsigned int add_ranges_num (int);
 static unsigned int add_ranges (const_tree);
 static void add_ranges_by_labels (dw_die_ref, const char *, const char *,
-				  bool *);
+				  bool *, bool);
 static void output_ranges (void);
 static dw_line_info_table *new_line_info_table (void);
-static void output_line_info (void);
+static void output_line_info (bool);
 static void output_file_names (void);
 static dw_die_ref base_type_die (tree);
 static int is_base_type (tree);
@@ -3504,36 +3532,124 @@  static bool generic_type_p (tree);
 static void schedule_generic_params_dies_gen (tree t);
 static void gen_scheduled_generic_parms_dies (void);
 
+/* Return the operator to use for an address of a variable.
+   DTPREL is true for thread-local variables whose address
+   is really an offset relative to the TLS pointer, which
+   will need link-time relocation, but will not need relocation 
+   by the DWARF consumer.  For those, we use DW_OP_const*.
+   For regular variables, which need both link-time relocation
+   and consumer-level relocation (e.g., to account for
+   shared objects loaded at a random address), we use 
+   DW_OP_addr*.  */
+
+static inline enum dwarf_location_atom dw_addr_op (bool dtprel)
+{
+  if (dtprel)
+    return (dwarf_split_debug_info ? DW_OP_GNU_const_index
+            : (DWARF2_ADDR_SIZE == 4 ? DW_OP_const4u : DW_OP_const8u));
+  else
+    return (dwarf_split_debug_info ? DW_OP_GNU_addr_index : DW_OP_addr);
+}
+
+/* Return a pointer to a newly allocated address location description.  If
+   dwarf_split_debug_info is true, then record the address with the appropriate
+   relocation.  */
+static inline dw_loc_descr_ref
+new_addr_loc_descr (rtx addr, int dtprel)
+{
+  dw_loc_descr_ref ref = new_loc_descr (dw_addr_op (dtprel), 0, 0);
+
+  ref->dw_loc_oprnd1.val_class = dw_val_class_addr;
+  ref->dw_loc_oprnd1.val_index = -1U;
+  ref->dw_loc_oprnd1.v.val_addr = addr;
+  ref->dtprel = dtprel;
+  if (dwarf_split_debug_info)
+    {
+      dw_attr_node attr;
+
+      attr.dw_attr = DW_AT_location;
+      attr.dw_attr_val.val_class = (dtprel
+                                    ? dw_val_class_loc : dw_val_class_addr);
+      attr.dw_attr_val.val_index = -1U;
+      attr.dw_attr_val.v.val_addr = addr;
+
+      ref->dw_loc_oprnd1.val_index = add_addr_table_entry (&attr);
+    }
+  return ref;
+}
+
 /* Section names used to hold DWARF debugging information.  */
+
 #ifndef DEBUG_INFO_SECTION
 #define DEBUG_INFO_SECTION	".debug_info"
 #endif
+#ifndef DEBUG_DWO_INFO_SECTION
+#define DEBUG_DWO_INFO_SECTION	".debug_info.dwo"
+#endif
 #ifndef DEBUG_ABBREV_SECTION
 #define DEBUG_ABBREV_SECTION	".debug_abbrev"
 #endif
+#ifndef DEBUG_DWO_ABBREV_SECTION
+#define DEBUG_DWO_ABBREV_SECTION ".debug_abbrev.dwo"
+#endif
 #ifndef DEBUG_ARANGES_SECTION
 #define DEBUG_ARANGES_SECTION	".debug_aranges"
 #endif
+#ifndef DEBUG_ADDR_SECTION
+#define DEBUG_ADDR_SECTION	".debug_addr"
+#endif
+#ifndef DEBUG_NORM_MACINFO_SECTION
+#define DEBUG_NORM_MACINFO_SECTION	".debug_macinfo"
+#endif
+#ifndef DEBUG_DWO_MACINFO_SECTION
+#define DEBUG_DWO_MACINFO_SECTION	".debug_macinfo.dwo"
+#endif
 #ifndef DEBUG_MACINFO_SECTION
-#define DEBUG_MACINFO_SECTION	".debug_macinfo"
+#define DEBUG_MACINFO_SECTION                                           \
+  (!dwarf_split_debug_info                                              \
+   ? (DEBUG_NORM_MACINFO_SECTION) : (DEBUG_DWO_MACINFO_SECTION))
+#endif
+#ifndef DEBUG_NORM_MACRO_SECTION
+#define DEBUG_NORM_MACRO_SECTION ".debug_macro"
+#endif
+#ifndef DEBUG_DWO_MACRO_SECTION
+#define DEBUG_DWO_MACRO_SECTION	".debug_macro.dwo"
 #endif
 #ifndef DEBUG_MACRO_SECTION
-#define DEBUG_MACRO_SECTION	".debug_macro"
+#define DEBUG_MACRO_SECTION                                             \
+  (!dwarf_split_debug_info                                              \
+   ? (DEBUG_NORM_MACRO_SECTION) : (DEBUG_DWO_MACRO_SECTION))
 #endif
 #ifndef DEBUG_LINE_SECTION
 #define DEBUG_LINE_SECTION	".debug_line"
 #endif
+#ifndef DEBUG_DWO_LINE_SECTION
+#define DEBUG_DWO_LINE_SECTION	".debug_line.dwo"
+#endif
 #ifndef DEBUG_LOC_SECTION
 #define DEBUG_LOC_SECTION	".debug_loc"
 #endif
+#ifndef DEBUG_DWO_LOC_SECTION
+#define DEBUG_DWO_LOC_SECTION	".debug_loc.dwo"
+#endif
 #ifndef DEBUG_PUBNAMES_SECTION
 #define DEBUG_PUBNAMES_SECTION	".debug_pubnames"
 #endif
 #ifndef DEBUG_PUBTYPES_SECTION
 #define DEBUG_PUBTYPES_SECTION	".debug_pubtypes"
 #endif
+#define DEBUG_NORM_STR_OFFSETS_SECTION ".debug_str_offsets"
+#define DEBUG_DWO_STR_OFFSETS_SECTION ".debug_str_offsets.dwo"
+#ifndef DEBUG_STR_OFFSETS_SECTION
+#define DEBUG_STR_OFFSETS_SECTION                                       \
+  (!dwarf_split_debug_info                                              \
+   ? (DEBUG_NORM_STR_OFFSETS_SECTION) : (DEBUG_DWO_STR_OFFSETS_SECTION))
+#endif
+#define DEBUG_DWO_STR_SECTION   ".debug_str.dwo"
+#define DEBUG_NORM_STR_SECTION  ".debug_str"
 #ifndef DEBUG_STR_SECTION
-#define DEBUG_STR_SECTION	".debug_str"
+#define DEBUG_STR_SECTION                               \
+  (!dwarf_split_debug_info ? (DEBUG_NORM_STR_SECTION) : (DEBUG_DWO_STR_SECTION))
 #endif
 #ifndef DEBUG_RANGES_SECTION
 #define DEBUG_RANGES_SECTION	".debug_ranges"
@@ -3544,11 +3660,17 @@  static void gen_scheduled_generic_parms_
 #define TEXT_SECTION_NAME	".text"
 #endif
 
+/* Section flags for .debug_macinfo/.debug_macro section.  */
+#define DEBUG_MACRO_SECTION_FLAGS \
+  (dwarf_split_debug_info ? SECTION_DEBUG | SECTION_EXCLUDE : SECTION_DEBUG)
+
 /* Section flags for .debug_str section.  */
 #define DEBUG_STR_SECTION_FLAGS \
-  (HAVE_GAS_SHF_MERGE && flag_merge_debug_strings		\
-   ? SECTION_DEBUG | SECTION_MERGE | SECTION_STRINGS | 1	\
-   : SECTION_DEBUG)
+  (dwarf_split_debug_info \
+   ? SECTION_DEBUG | SECTION_EXCLUDE \
+   : (HAVE_GAS_SHF_MERGE && flag_merge_debug_strings \
+      ? SECTION_DEBUG | SECTION_MERGE | SECTION_STRINGS | 1        \
+      : SECTION_DEBUG))
 
 /* Labels we insert at beginning sections we can reference instead of
    the section names themselves.  */
@@ -3568,12 +3690,24 @@  static void gen_scheduled_generic_parms_
 #ifndef DEBUG_LINE_SECTION_LABEL
 #define DEBUG_LINE_SECTION_LABEL	"Ldebug_line"
 #endif
+#ifndef DEBUG_SKELETON_LINE_SECTION_LABEL
+#define DEBUG_SKELETON_LINE_SECTION_LABEL   "Lskeleton_debug_line"
+#endif
 #ifndef DEBUG_INFO_SECTION_LABEL
 #define DEBUG_INFO_SECTION_LABEL	"Ldebug_info"
 #endif
+#ifndef DEBUG_SKELETON_INFO_SECTION_LABEL
+#define DEBUG_SKELETON_INFO_SECTION_LABEL   "Lskeleton_debug_info"
+#endif
 #ifndef DEBUG_ABBREV_SECTION_LABEL
 #define DEBUG_ABBREV_SECTION_LABEL	"Ldebug_abbrev"
 #endif
+#ifndef DEBUG_SKELETON_ABBREV_SECTION_LABEL
+#define DEBUG_SKELETON_ABBREV_SECTION_LABEL "Lskeleton_debug_abbrev"
+#endif
+#ifndef DEBUG_ADDR_SECTION_LABEL
+#define DEBUG_ADDR_SECTION_LABEL	    "Ldebug_addr"
+#endif
 #ifndef DEBUG_LOC_SECTION_LABEL
 #define DEBUG_LOC_SECTION_LABEL		"Ldebug_loc"
 #endif
@@ -3587,6 +3721,9 @@  static void gen_scheduled_generic_parms_
 #define DEBUG_MACRO_SECTION_LABEL	"Ldebug_macro"
 #endif
 
+#define SKELETON_COMP_DIE_ABBREV 1
+#define SKELETON_TYPE_DIE_ABBREV 2
+
 
 /* Definitions of defaults for formats and names of various special
    (artificial) labels which may be generated within this file (when the -g
@@ -3600,7 +3737,11 @@  static char cold_text_section_label[MAX_
 static char cold_end_label[MAX_ARTIFICIAL_LABEL_BYTES];
 static char abbrev_section_label[MAX_ARTIFICIAL_LABEL_BYTES];
 static char debug_info_section_label[MAX_ARTIFICIAL_LABEL_BYTES];
+static char debug_skeleton_info_section_label[MAX_ARTIFICIAL_LABEL_BYTES];
+static char debug_skeleton_abbrev_section_label[MAX_ARTIFICIAL_LABEL_BYTES];
 static char debug_line_section_label[MAX_ARTIFICIAL_LABEL_BYTES];
+static char debug_addr_section_label[MAX_ARTIFICIAL_LABEL_BYTES];
+static char debug_skeleton_line_section_label[MAX_ARTIFICIAL_LABEL_BYTES];
 static char debug_pubnames_section_label[MAX_ARTIFICIAL_LABEL_BYTES];
 static char debug_pubtypes_section_label[MAX_ARTIFICIAL_LABEL_BYTES];
 static char macinfo_section_label[MAX_ARTIFICIAL_LABEL_BYTES];
@@ -4271,6 +4412,31 @@  AT_class (dw_attr_ref a)
   return a->dw_attr_val.val_class;
 }
 
+/* Return the index for any attribute that will be referenced with a
+   DW_FORM_GNU_addr_index.  Strings have their indices handled differently to
+   account for reference counting pruning.  */
+
+static inline unsigned int
+AT_index (dw_attr_ref a)
+{
+  if (AT_class (a) == dw_val_class_str)
+    return a->dw_attr_val.v.val_str->index;
+  else
+    return a->dw_attr_val.val_index;
+}
+
+/* Set the index for any attribute that will be referenced with a
+   DW_FORM_GNU_addr_index.  */
+
+static inline void
+set_AT_index (dw_attr_ref a, unsigned int index)
+{
+  if (AT_class (a) == dw_val_class_str)
+    a->dw_attr_val.v.val_str->index = index;
+  else
+    a->dw_attr_val.val_index = index;
+}
+
 /* Add a flag value attribute to a DIE.  */
 
 static inline void
@@ -4280,6 +4446,7 @@  add_AT_flag (dw_die_ref die, enum dwarf_
 
   attr.dw_attr = attr_kind;
   attr.dw_attr_val.val_class = dw_val_class_flag;
+  attr.dw_attr_val.val_index = -1U;
   attr.dw_attr_val.v.val_flag = flag;
   add_dwarf_attr (die, &attr);
 }
@@ -4300,6 +4467,7 @@  add_AT_int (dw_die_ref die, enum dwarf_a
 
   attr.dw_attr = attr_kind;
   attr.dw_attr_val.val_class = dw_val_class_const;
+  attr.dw_attr_val.val_index = -1U;
   attr.dw_attr_val.v.val_int = int_val;
   add_dwarf_attr (die, &attr);
 }
@@ -4321,6 +4489,7 @@  add_AT_unsigned (dw_die_ref die, enum dw
 
   attr.dw_attr = attr_kind;
   attr.dw_attr_val.val_class = dw_val_class_unsigned_const;
+  attr.dw_attr_val.val_index = -1U;
   attr.dw_attr_val.v.val_unsigned = unsigned_val;
   add_dwarf_attr (die, &attr);
 }
@@ -4342,6 +4511,7 @@  add_AT_double (dw_die_ref die, enum dwar
 
   attr.dw_attr = attr_kind;
   attr.dw_attr_val.val_class = dw_val_class_const_double;
+  attr.dw_attr_val.val_index = -1U;
   attr.dw_attr_val.v.val_double.high = high;
   attr.dw_attr_val.v.val_double.low = low;
   add_dwarf_attr (die, &attr);
@@ -4357,6 +4527,7 @@  add_AT_vec (dw_die_ref die, enum dwarf_a
 
   attr.dw_attr = attr_kind;
   attr.dw_attr_val.val_class = dw_val_class_vec;
+  attr.dw_attr_val.val_index = -1U;
   attr.dw_attr_val.v.val_vec.length = length;
   attr.dw_attr_val.v.val_vec.elt_size = elt_size;
   attr.dw_attr_val.v.val_vec.array = array;
@@ -4373,6 +4544,7 @@  add_AT_data8 (dw_die_ref die, enum dwarf
 
   attr.dw_attr = attr_kind;
   attr.dw_attr_val.val_class = dw_val_class_data8;
+  attr.dw_attr_val.val_index = -1U;
   memcpy (attr.dw_attr_val.v.val_data8, data8, 8);
   add_dwarf_attr (die, &attr);
 }
@@ -4431,6 +4603,7 @@  add_AT_string (dw_die_ref die, enum dwar
 
   attr.dw_attr = attr_kind;
   attr.dw_attr_val.val_class = dw_val_class_str;
+  attr.dw_attr_val.val_index = -1U;
   attr.dw_attr_val.v.val_str = node;
   add_dwarf_attr (die, &attr);
 }
@@ -4442,12 +4615,20 @@  AT_string (dw_attr_ref a)
   return a->dw_attr_val.v.val_str->str;
 }
 
+/* A vector for a table of strings in the form DW_FORM_GNU_index_str.  */
+
+typedef struct indirect_string_node indirect_string_node;
+DEF_VEC_O(indirect_string_node);
+DEF_VEC_ALLOC_O(indirect_string_node, gc);
+static GTY (()) VEC (indirect_string_node, gc) *index_string_table;
+
 /* Find out whether a string should be output inline in DIE
    or out-of-line in .debug_str section.  */
 
 static enum dwarf_form
 AT_string_form (dw_attr_ref a)
 {
+  static unsigned int index_string_count = 0;
   struct indirect_string_node *node;
   unsigned int len;
   char label[32];
@@ -4477,7 +4658,17 @@  AT_string_form (dw_attr_ref a)
   ++dw2_string_counter;
   node->label = xstrdup (label);
 
-  return node->form = DW_FORM_strp;
+  if (!dwarf_split_debug_info)
+    node->form = DW_FORM_strp;
+  else
+    {
+      node->form = DW_FORM_GNU_str_index;
+      set_AT_index (a, index_string_count);
+      index_string_count++;
+      VEC_safe_push (indirect_string_node, gc, index_string_table, node);
+    }
+
+  return node->form;
 }
 
 /* Add a DIE reference attribute value to a DIE.  */
@@ -4498,6 +4689,7 @@  add_AT_die_ref (dw_die_ref die, enum dwa
 
   attr.dw_attr = attr_kind;
   attr.dw_attr_val.val_class = dw_val_class_die_ref;
+  attr.dw_attr_val.val_index = -1U;
   attr.dw_attr_val.v.val_die_ref.die = targ_die;
   attr.dw_attr_val.v.val_die_ref.external = 0;
   add_dwarf_attr (die, &attr);
@@ -4546,6 +4738,7 @@  add_AT_fde_ref (dw_die_ref die, enum dwa
 
   attr.dw_attr = attr_kind;
   attr.dw_attr_val.val_class = dw_val_class_fde_ref;
+  attr.dw_attr_val.val_index = -1U;
   attr.dw_attr_val.v.val_fde_index = targ_fde;
   add_dwarf_attr (die, &attr);
 }
@@ -4559,6 +4752,7 @@  add_AT_loc (dw_die_ref die, enum dwarf_a
 
   attr.dw_attr = attr_kind;
   attr.dw_attr_val.val_class = dw_val_class_loc;
+  attr.dw_attr_val.val_index = -1U;
   attr.dw_attr_val.v.val_loc = loc;
   add_dwarf_attr (die, &attr);
 }
@@ -4577,6 +4771,7 @@  add_AT_loc_list (dw_die_ref die, enum dw
 
   attr.dw_attr = attr_kind;
   attr.dw_attr_val.val_class = dw_val_class_loc_list;
+  attr.dw_attr_val.val_index = -1U;
   attr.dw_attr_val.v.val_loc_list = loc_list;
   add_dwarf_attr (die, &attr);
   have_location_lists = true;
@@ -4596,17 +4791,64 @@  AT_loc_list_ptr (dw_attr_ref a)
   return &a->dw_attr_val.v.val_loc_list;
 }
 
+/* A table of entries into the .debug_addr section.  */
+
+static GTY (()) VEC (dw_attr_node,gc) * addr_index_table;
+
+static unsigned int
+add_addr_table_entry (dw_attr_node *attr)
+{
+  gcc_assert (dwarf_split_debug_info);
+
+  VEC_safe_push (dw_attr_node, gc, addr_index_table, attr);
+  return VEC_length (dw_attr_node, addr_index_table) - 1;
+}
+
+/* Remove an entry from the addr table.  Since we have already numbered
+   all the entries, the best we can do here is null it out.  */
+
+static void
+remove_addr_table_entry (unsigned int i)
+{
+  dw_attr_node *attr;
+
+  gcc_assert (dwarf_split_debug_info);
+  gcc_assert (i < VEC_length (dw_attr_node, addr_index_table));
+
+  attr = VEC_index (dw_attr_node, addr_index_table, i);
+  attr->dw_attr = (enum dwarf_attribute) 0;
+}
+
+/* Given a location list, remove all addresses it refers to from the
+   address_table.  */
+
+static void
+remove_loc_list_addr_table_entries (dw_loc_list_ref loc)
+{
+  dw_loc_descr_ref descr;
+
+  gcc_assert (loc->replaced);
+
+  for (descr = loc->expr; descr; descr = descr->dw_loc_next)
+    if (descr->dw_loc_oprnd1.val_index != -1U)
+      remove_addr_table_entry (descr->dw_loc_oprnd1.val_index);
+}
+
 /* Add an address constant attribute value to a DIE.  */
 
 static inline void
-add_AT_addr (dw_die_ref die, enum dwarf_attribute attr_kind, rtx addr)
+add_AT_addr (dw_die_ref die, enum dwarf_attribute attr_kind, rtx addr,
+	     bool force_direct)
 {
   dw_attr_node attr;
 
   attr.dw_attr = attr_kind;
   attr.dw_attr_val.val_class = dw_val_class_addr;
+  attr.dw_attr_val.val_index = -1U;
   attr.dw_attr_val.v.val_addr = addr;
   add_dwarf_attr (die, &attr);
+  if (dwarf_split_debug_info && !force_direct)
+    set_AT_index (get_AT (die, attr_kind), add_addr_table_entry (&attr));
 }
 
 /* Get the RTX from to an address DIE attribute.  */
@@ -4628,6 +4870,7 @@  add_AT_file (dw_die_ref die, enum dwarf_
 
   attr.dw_attr = attr_kind;
   attr.dw_attr_val.val_class = dw_val_class_file;
+  attr.dw_attr_val.val_index = -1U;
   attr.dw_attr_val.v.val_file = fd;
   add_dwarf_attr (die, &attr);
 }
@@ -4651,6 +4894,7 @@  add_AT_vms_delta (dw_die_ref die, enum d
 
   attr.dw_attr = attr_kind;
   attr.dw_attr_val.val_class = dw_val_class_vms_delta;
+  attr.dw_attr_val.val_index = -1U;
   attr.dw_attr_val.v.val_vms_delta.lbl1 = xstrdup (lbl1);
   attr.dw_attr_val.v.val_vms_delta.lbl2 = xstrdup (lbl2);
   add_dwarf_attr (die, &attr);
@@ -4659,14 +4903,18 @@  add_AT_vms_delta (dw_die_ref die, enum d
 /* Add a label identifier attribute value to a DIE.  */
 
 static inline void
-add_AT_lbl_id (dw_die_ref die, enum dwarf_attribute attr_kind, const char *lbl_id)
+add_AT_lbl_id (dw_die_ref die, enum dwarf_attribute attr_kind,
+	       const char *lbl_id, bool force_direct)
 {
   dw_attr_node attr;
 
   attr.dw_attr = attr_kind;
   attr.dw_attr_val.val_class = dw_val_class_lbl_id;
+  attr.dw_attr_val.val_index = -1U;
   attr.dw_attr_val.v.val_lbl_id = xstrdup (lbl_id);
   add_dwarf_attr (die, &attr);
+  if (dwarf_split_debug_info && !force_direct)
+    set_AT_index (get_AT (die, attr_kind), add_addr_table_entry (&attr));
 }
 
 /* Add a section offset attribute value to a DIE, an offset into the
@@ -4680,6 +4928,7 @@  add_AT_lineptr (dw_die_ref die, enum dwa
 
   attr.dw_attr = attr_kind;
   attr.dw_attr_val.val_class = dw_val_class_lineptr;
+  attr.dw_attr_val.val_index = -1U;
   attr.dw_attr_val.v.val_lbl_id = xstrdup (label);
   add_dwarf_attr (die, &attr);
 }
@@ -4695,6 +4944,7 @@  add_AT_macptr (dw_die_ref die, enum dwar
 
   attr.dw_attr = attr_kind;
   attr.dw_attr_val.val_class = dw_val_class_macptr;
+  attr.dw_attr_val.val_index = -1U;
   attr.dw_attr_val.v.val_lbl_id = xstrdup (label);
   add_dwarf_attr (die, &attr);
 }
@@ -4709,20 +4959,25 @@  add_AT_offset (dw_die_ref die, enum dwar
 
   attr.dw_attr = attr_kind;
   attr.dw_attr_val.val_class = dw_val_class_offset;
+  attr.dw_attr_val.val_index = -1U;
   attr.dw_attr_val.v.val_offset = offset;
   add_dwarf_attr (die, &attr);
 }
 
-/* Add an range_list attribute value to a DIE.  */
+/* Add a range_list attribute value to a DIE.  */
 
 static void
 add_AT_range_list (dw_die_ref die, enum dwarf_attribute attr_kind,
-		   long unsigned int offset)
+		   long unsigned int offset, bool force_direct)
 {
   dw_attr_node attr;
 
   attr.dw_attr = attr_kind;
   attr.dw_attr_val.val_class = dw_val_class_range_list;
+  /* This is a bit of a misnomer--the offset isn't an index, but we need to
+     save force_direct for output.  */
+  attr.dw_attr_val.val_index
+      = (dwarf_split_debug_info && !force_direct) ? offset : -1U;
   attr.dw_attr_val.v.val_offset = offset;
   add_dwarf_attr (die, &attr);
 }
@@ -7716,6 +7971,7 @@  size_of_die (dw_die_ref die)
   unsigned long size = 0;
   dw_attr_ref a;
   unsigned ix;
+  enum dwarf_form form;
 
   size += size_of_uleb128 (die->die_abbrev);
   FOR_EACH_VEC_ELT (dw_attr_node, die->die_attr, ix, a)
@@ -7723,7 +7979,10 @@  size_of_die (dw_die_ref die)
       switch (AT_class (a))
 	{
 	case dw_val_class_addr:
-	  size += DWARF2_ADDR_SIZE;
+          if (dwarf_split_debug_info && AT_index (a) != -1U)
+            size += size_of_uleb128 (AT_index (a));
+          else
+            size += DWARF2_ADDR_SIZE;
 	  break;
 	case dw_val_class_offset:
 	  size += DWARF_OFFSET_SIZE;
@@ -7741,10 +8000,13 @@  size_of_die (dw_die_ref die)
 	  }
 	  break;
 	case dw_val_class_loc_list:
-	  size += DWARF_OFFSET_SIZE;
+          if (dwarf_split_debug_info && AT_index (a) != -1U)
+            size += size_of_uleb128 (AT_index (a));
+          else
+            size += DWARF_OFFSET_SIZE;
 	  break;
 	case dw_val_class_range_list:
-	  size += DWARF_OFFSET_SIZE;
+          size += DWARF_OFFSET_SIZE;
 	  break;
 	case dw_val_class_const:
 	  size += size_of_sleb128 (AT_int (a));
@@ -7804,15 +8066,21 @@  size_of_die (dw_die_ref die)
 	  size += DWARF_OFFSET_SIZE;
 	  break;
 	case dw_val_class_lbl_id:
-	  size += DWARF2_ADDR_SIZE;
+          if (dwarf_split_debug_info && AT_index (a) != -1U)
+            size += size_of_uleb128 (AT_index (a));
+          else
+            size += DWARF2_ADDR_SIZE;
 	  break;
 	case dw_val_class_lineptr:
 	case dw_val_class_macptr:
-	  size += DWARF_OFFSET_SIZE;
+          size += DWARF_OFFSET_SIZE;
 	  break;
 	case dw_val_class_str:
-	  if (AT_string_form (a) == DW_FORM_strp)
+          form = AT_string_form (a);
+          if (form == DW_FORM_strp)
 	    size += DWARF_OFFSET_SIZE;
+	  else if (form == DW_FORM_GNU_str_index)
+            size += size_of_uleb128 (AT_index (a));
 	  else
 	    size += strlen (a->dw_attr_val.v.val_str->str) + 1;
 	  break;
@@ -7994,7 +8262,7 @@  size_of_aranges (void)
 static enum dwarf_form
 value_format (dw_attr_ref a)
 {
-  switch (a->dw_attr_val.val_class)
+  switch (AT_class (a))
     {
     case dw_val_class_addr:
       /* Only very few attributes allow DW_FORM_addr.  */
@@ -8004,7 +8272,8 @@  value_format (dw_attr_ref a)
 	case DW_AT_high_pc:
 	case DW_AT_entry_pc:
 	case DW_AT_trampoline:
-	  return DW_FORM_addr;
+          return (dwarf_split_debug_info && AT_index (a) != -1U
+		  ? DW_FORM_GNU_addr_index : DW_FORM_addr);
 	default:
 	  break;
 	}
@@ -8023,7 +8292,7 @@  value_format (dw_attr_ref a)
 	}
     case dw_val_class_range_list:
     case dw_val_class_loc_list:
-      if (dwarf_version >= 4)
+      if (dwarf_version >= 4 || dwarf_split_debug_info)
 	return DW_FORM_sec_offset;
       /* FALLTHRU */
     case dw_val_class_vms_delta:
@@ -8120,7 +8389,8 @@  value_format (dw_attr_ref a)
     case dw_val_class_fde_ref:
       return DW_FORM_data;
     case dw_val_class_lbl_id:
-      return DW_FORM_addr;
+      return (dwarf_split_debug_info && AT_index (a) != -1U
+	      ? DW_FORM_GNU_addr_index : DW_FORM_addr);
     case dw_val_class_lineptr:
     case dw_val_class_macptr:
       return dwarf_version >= 4 ? DW_FORM_sec_offset : DW_FORM_data;
@@ -8157,40 +8427,46 @@  output_value_format (dw_attr_ref a)
   dw2_asm_output_data_uleb128 (form, "(%s)", dwarf_form_name (form));
 }
 
-/* Output the .debug_abbrev section which defines the DIE abbreviation
-   table.  */
+/* Given a die and id, produce the appropriate abbreviations.  */
 
 static void
-output_abbrev_section (void)
+output_die_abbrevs (unsigned long abbrev_id, dw_die_ref abbrev)
 {
-  unsigned long abbrev_id;
+  unsigned ix;
+  dw_attr_ref a_attr;
 
-  for (abbrev_id = 1; abbrev_id < abbrev_die_table_in_use; ++abbrev_id)
+  dw2_asm_output_data_uleb128 (abbrev_id, "(abbrev code)");
+  dw2_asm_output_data_uleb128 (abbrev->die_tag, "(TAG: %s)",
+                               dwarf_tag_name (abbrev->die_tag));
+
+  if (abbrev->die_child != NULL)
+    dw2_asm_output_data (1, DW_children_yes, "DW_children_yes");
+  else
+    dw2_asm_output_data (1, DW_children_no, "DW_children_no");
+
+  for (ix = 0; VEC_iterate (dw_attr_node, abbrev->die_attr, ix, a_attr);
+       ix++)
     {
-      dw_die_ref abbrev = abbrev_die_table[abbrev_id];
-      unsigned ix;
-      dw_attr_ref a_attr;
+      dw2_asm_output_data_uleb128 (a_attr->dw_attr, "(%s)",
+                                   dwarf_attr_name (a_attr->dw_attr));
+      output_value_format (a_attr);
+    }
+
+  dw2_asm_output_data (1, 0, NULL);
+  dw2_asm_output_data (1, 0, NULL);
+}
 
-      dw2_asm_output_data_uleb128 (abbrev_id, "(abbrev code)");
-      dw2_asm_output_data_uleb128 (abbrev->die_tag, "(TAG: %s)",
-				   dwarf_tag_name (abbrev->die_tag));
 
-      if (abbrev->die_child != NULL)
-	dw2_asm_output_data (1, DW_children_yes, "DW_children_yes");
-      else
-	dw2_asm_output_data (1, DW_children_no, "DW_children_no");
+/* Output the .debug_abbrev section which defines the DIE abbreviation
+   table.  */
 
-      for (ix = 0; VEC_iterate (dw_attr_node, abbrev->die_attr, ix, a_attr);
-	   ix++)
-	{
-	  dw2_asm_output_data_uleb128 (a_attr->dw_attr, "(%s)",
-				       dwarf_attr_name (a_attr->dw_attr));
-	  output_value_format (a_attr);
-	}
+static void
+output_abbrev_section (void)
+{
+  unsigned long abbrev_id;
 
-      dw2_asm_output_data (1, 0, NULL);
-      dw2_asm_output_data (1, 0, NULL);
-    }
+  for (abbrev_id = 1; abbrev_id < abbrev_die_table_in_use; ++abbrev_id)
+    output_die_abbrevs (abbrev_id, abbrev_die_table[abbrev_id]);
 
   /* Terminate the table.  */
   dw2_asm_output_data (1, 0, NULL);
@@ -8225,6 +8501,7 @@  new_loc_list (dw_loc_descr_ref expr, con
   dw_loc_list_ref retlist = ggc_alloc_cleared_dw_loc_list_node ();
 
   retlist->begin = begin;
+  retlist->begin_index = -1U;
   retlist->end = end;
   retlist->expr = expr;
   retlist->section = section;
@@ -8269,7 +8546,22 @@  output_loc_list (dw_loc_list_ref list_he
 	 in a single range are unlikely very useful.  */
       if (size > 0xffff)
 	continue;
-      if (!have_multiple_function_sections)
+      if (dwarf_split_debug_info)
+        {
+          dw2_asm_output_data (1, DW_LLE_start_length_entry,
+                               "Location list start/length entry (%s)",
+                               list_head->ll_symbol);
+          dw2_asm_output_data_uleb128 (curr->begin_index,
+                                       "Location list range start index (%s)",
+                                       curr->begin);
+          /* The length field is 4 bytes.  If we ever need to support
+	     an 8-byte length, we can add a new DW_LLE code or fall back
+	     to DW_LLE_start_end_entry.  */
+          dw2_asm_output_delta (4, curr->end, curr->begin,
+				"Location list range length (%s)",
+				list_head->ll_symbol);
+        }
+      else if (!have_multiple_function_sections)
 	{
 	  dw2_asm_output_delta (DWARF2_ADDR_SIZE, curr->begin, curr->section,
 				"Location list begin address (%s)",
@@ -8295,12 +8587,83 @@  output_loc_list (dw_loc_list_ref list_he
       output_loc_sequence (curr->expr, -1);
     }
 
-  dw2_asm_output_data (DWARF2_ADDR_SIZE, 0,
-		       "Location list terminator begin (%s)",
-		       list_head->ll_symbol);
-  dw2_asm_output_data (DWARF2_ADDR_SIZE, 0,
-		       "Location list terminator end (%s)",
-		       list_head->ll_symbol);
+  if (dwarf_split_debug_info)
+    dw2_asm_output_data (1, DW_LLE_end_of_list_entry,
+			 "Location list terminator (%s)",
+			 list_head->ll_symbol);
+  else
+    {
+      dw2_asm_output_data (DWARF2_ADDR_SIZE, 0,
+			   "Location list terminator begin (%s)",
+			   list_head->ll_symbol);
+      dw2_asm_output_data (DWARF2_ADDR_SIZE, 0,
+			   "Location list terminator end (%s)",
+			   list_head->ll_symbol);
+    }
+}
+
+/* Output the offset into the debug_range section.  */
+
+static void
+output_range_list_offset (dw_attr_ref a)
+{
+  const char *name = dwarf_attr_name (a->dw_attr);
+
+  if (!dwarf_split_debug_info || AT_index (a) == -1U)
+    {
+      char *p = strchr (ranges_section_label, '\0');
+      sprintf (p, "+" HOST_WIDE_INT_PRINT_HEX, a->dw_attr_val.v.val_offset);
+      dw2_asm_output_offset (DWARF_OFFSET_SIZE, ranges_section_label,
+                             debug_ranges_section, "%s", name);
+      *p = '\0';
+    }
+  else
+    dw2_asm_output_data (DWARF_OFFSET_SIZE, a->dw_attr_val.v.val_offset,
+                         "%s (offset from %s)", name, ranges_section_label);
+}
+
+/* Output the offset into the debug_loc section.  */
+
+static void
+output_loc_list_offset (dw_attr_ref a)
+{
+  char *sym = AT_loc_list (a)->ll_symbol;
+
+  gcc_assert (sym);
+  if (dwarf_split_debug_info)
+    dw2_asm_output_delta (DWARF_OFFSET_SIZE, sym, loc_section_label,
+                          "%s", dwarf_attr_name (a->dw_attr));
+  else
+    dw2_asm_output_offset (DWARF_OFFSET_SIZE, sym, debug_loc_section,
+                           "%s", dwarf_attr_name (a->dw_attr));
+}
+
+/* Output an attribute's index or value appropriately.  */
+
+static void
+output_attr_index_or_value (dw_attr_ref a)
+{
+  const char *name = dwarf_attr_name (a->dw_attr);
+
+  if (dwarf_split_debug_info && AT_index (a) != -1U)
+    {
+      dw2_asm_output_data_uleb128 (AT_index (a), "%s", name);
+      return;
+    }
+  switch (AT_class (a))
+    {
+      case dw_val_class_addr:
+        dw2_asm_output_addr_rtx (DWARF2_ADDR_SIZE, AT_addr (a), "%s", name);
+        break;
+      case dw_val_class_lbl_id:
+        dw2_asm_output_addr (DWARF2_ADDR_SIZE, AT_lbl (a), "%s", name);
+        break;
+      case dw_val_class_loc_list:
+        output_loc_list_offset (a);
+        break;
+      default:
+        gcc_unreachable ();
+    }
 }
 
 /* Output a type signature.  */
@@ -8341,7 +8704,7 @@  output_die (dw_die_ref die)
       switch (AT_class (a))
 	{
 	case dw_val_class_addr:
-	  dw2_asm_output_addr_rtx (DWARF2_ADDR_SIZE, AT_addr (a), "%s", name);
+          output_attr_index_or_value (a);
 	  break;
 
 	case dw_val_class_offset:
@@ -8350,15 +8713,7 @@  output_die (dw_die_ref die)
 	  break;
 
 	case dw_val_class_range_list:
-	  {
-	    char *p = strchr (ranges_section_label, '\0');
-
-	    sprintf (p, "+" HOST_WIDE_INT_PRINT_HEX,
-		     a->dw_attr_val.v.val_offset);
-	    dw2_asm_output_offset (DWARF_OFFSET_SIZE, ranges_section_label,
-				   debug_ranges_section, "%s", name);
-	    *p = '\0';
-	  }
+          output_range_list_offset (a);
 	  break;
 
 	case dw_val_class_loc:
@@ -8414,7 +8769,7 @@  output_die (dw_die_ref die)
 	      }
 
 	    dw2_asm_output_data (HOST_BITS_PER_WIDE_INT / HOST_BITS_PER_CHAR,
-				 first, name);
+				 first, "%s", name);
 	    dw2_asm_output_data (HOST_BITS_PER_WIDE_INT / HOST_BITS_PER_CHAR,
 				 second, NULL);
 	  }
@@ -8461,13 +8816,7 @@  output_die (dw_die_ref die)
 	  break;
 
 	case dw_val_class_loc_list:
-	  {
-	    char *sym = AT_loc_list (a)->ll_symbol;
-
-	    gcc_assert (sym);
-	    dw2_asm_output_offset (DWARF_OFFSET_SIZE, sym, debug_loc_section,
-				   "%s", name);
-	  }
+          output_attr_index_or_value (a);
 	  break;
 
 	case dw_val_class_die_ref:
@@ -8524,7 +8873,7 @@  output_die (dw_die_ref die)
 	  break;
 
 	case dw_val_class_lbl_id:
-	  dw2_asm_output_addr (DWARF2_ADDR_SIZE, AT_lbl (a), "%s", name);
+          output_attr_index_or_value (a);
 	  break;
 
 	case dw_val_class_lineptr:
@@ -8538,12 +8887,15 @@  output_die (dw_die_ref die)
 	  break;
 
 	case dw_val_class_str:
-	  if (AT_string_form (a) == DW_FORM_strp)
+	  if (a->dw_attr_val.v.val_str->form == DW_FORM_strp)
 	    dw2_asm_output_offset (DWARF_OFFSET_SIZE,
 				   a->dw_attr_val.v.val_str->label,
 				   debug_str_section,
 				   "%s: \"%s\"", name, AT_string (a));
-	  else
+	  else if (a->dw_attr_val.v.val_str->form == DW_FORM_GNU_str_index)
+            dw2_asm_output_data_uleb128 (AT_index (a),
+                                         "%s: \"%s\"", name, AT_string (a));
+          else
 	    dw2_asm_output_nstring (AT_string (a), -1, "%s", name);
 	  break;
 
@@ -8683,6 +9035,103 @@  add_AT_pubnames (dw_die_ref die)
     }
 }
 
+/* Helper function to generate top-level dies for skeleton debug_info and
+   debug_types.  */
+
+static void
+add_top_level_skeleton_die_attrs (dw_die_ref die)
+{
+  const char *dwo_file_name = concat (aux_base_name, ".dwo", NULL);
+  dw_attr_ref attr;
+
+  add_comp_dir_attribute (die);
+  add_AT_string (die, DW_AT_GNU_dwo_name, dwo_file_name);
+  /* The specification suggests that these attributes be inline to avoid
+     having a .debug_str section.  We know that they exist in the die because
+     we just added them.  */
+  attr = get_AT (die, DW_AT_GNU_dwo_name);
+  attr->dw_attr_val.v.val_str->form = DW_FORM_string;
+  attr = get_AT (die, DW_AT_comp_dir);
+  attr->dw_attr_val.v.val_str->form = DW_FORM_string;
+
+  add_AT_pubnames (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 split_debug_sections with use_type info, all type units int 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;
+}
+
+/* The splitter will fill in this value.  */
+
+unsigned char dwo_id_placeholder[8] = { 0, 0, 0, 0, 0, 0, 0, 0 };
+
+/* Output skeleton debug sections that point to the dwo file.  */
+
+static void
+output_skeleton_debug_sections (dw_die_ref comp_unit)
+{
+  /* These attributes will be found in the full debug_info section.  */
+  remove_AT (comp_unit, DW_AT_producer);
+  remove_AT (comp_unit, DW_AT_language);
+
+  /* Add attributes common to skeleton compile_units and type_units.  */
+  add_top_level_skeleton_die_attrs (comp_unit);
+
+  /* The dwo_id is only for compile_units.  */
+  add_AT_data8 (comp_unit, DW_AT_GNU_dwo_id, dwo_id_placeholder);
+
+  switch_to_section (debug_skeleton_info_section);
+  ASM_OUTPUT_LABEL (asm_out_file, debug_skeleton_info_section_label);
+
+  /* Produce the skeleton compilation-unit header.  This one differs enough from
+     a normal CU header that it's better not to call output_compilation_unit
+     header.  */
+  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 (comp_unit),
+		       "Length of Compilation 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)");
+
+  comp_unit->die_abbrev = 1;
+  output_die (comp_unit);
+
+  /* Build the skeleton debug_abbrev section.  */
+  switch_to_section (debug_skeleton_abbrev_section);
+  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");
+}
+
 /* Output a comdat type unit DIE and its children.  */
 
 static void
@@ -8705,7 +9154,11 @@  output_comdat_type_unit (comdat_type_nod
   calc_die_sizes (node->root_die);
 
 #if defined (OBJECT_FORMAT_ELF)
-  secname = ".debug_types";
+  if (!dwarf_split_debug_info)
+    secname = ".debug_types";
+  else
+    secname = ".debug_types.dwo";
+
   tmp = XALLOCAVEC (char, 4 + DWARF_TYPE_SIGNATURE_SIZE * 2);
   sprintf (tmp, "wt.");
   for (i = 0; i < DWARF_TYPE_SIGNATURE_SIZE; i++)
@@ -8714,6 +9167,7 @@  output_comdat_type_unit (comdat_type_nod
   targetm.asm_out.named_section (secname,
                                  SECTION_DEBUG | SECTION_LINKONCE,
                                  comdat_key);
+
 #else
   tmp = XALLOCAVEC (char, 18 + DWARF_TYPE_SIGNATURE_SIZE * 2);
   sprintf (tmp, ".gnu.linkonce.wt.");
@@ -8731,6 +9185,37 @@  output_comdat_type_unit (comdat_type_nod
   output_die (node->root_die);
 
   unmark_dies (node->root_die);
+
+  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");
+
+      /* One for the terminating NULL byte.  */
+      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 ());
+    }
 }
 
 /* Return the DWARF2/3 pubname associated with a decl.  */
@@ -8880,9 +9365,14 @@  output_pubnames (VEC (pubname_entry, gc)
 			 "Length of Public Type Names Info");
   /* Version number for pubnames/pubtypes is still 2, even in DWARF3.  */
   dw2_asm_output_data (2, 2, "DWARF Version");
-  dw2_asm_output_offset (DWARF_OFFSET_SIZE, debug_info_section_label,
-			 debug_info_section,
-			 "Offset of Compilation Unit Info");
+  if (dwarf_split_debug_info)
+    dw2_asm_output_offset (DWARF_OFFSET_SIZE, debug_skeleton_info_section_label,
+                           debug_skeleton_info_section,
+                           "Offset of Compilation Unit Info");
+  else
+    dw2_asm_output_offset (DWARF_OFFSET_SIZE, debug_info_section_label,
+                           debug_info_section,
+                           "Offset of Compilation Unit Info");
   dw2_asm_output_data (DWARF_OFFSET_SIZE, next_die_offset,
 		       "Compilation Unit Length");
 
@@ -8937,9 +9427,14 @@  output_aranges (unsigned long aranges_le
 		       "Length of Address Ranges Info");
   /* Version number for aranges is still 2, even in DWARF3.  */
   dw2_asm_output_data (2, 2, "DWARF Version");
-  dw2_asm_output_offset (DWARF_OFFSET_SIZE, debug_info_section_label,
-			 debug_info_section,
-			 "Offset of Compilation Unit Info");
+  if (dwarf_split_debug_info)
+    dw2_asm_output_offset (DWARF_OFFSET_SIZE, debug_skeleton_info_section_label,
+                           debug_skeleton_info_section,
+                           "Offset of Compilation Unit Info");
+  else
+    dw2_asm_output_offset (DWARF_OFFSET_SIZE, debug_info_section_label,
+                           debug_info_section,
+                           "Offset of Compilation Unit Info");
   dw2_asm_output_data (1, DWARF2_ADDR_SIZE, "Size of Address");
   dw2_asm_output_data (1, 0, "Size of Segment Descriptor");
 
@@ -9039,7 +9534,7 @@  add_ranges (const_tree block)
 
 static void
 add_ranges_by_labels (dw_die_ref die, const char *begin, const char *end,
-		      bool *added)
+		      bool *added, bool force_direct)
 {
   unsigned int in_use = ranges_by_label_in_use;
   unsigned int offset;
@@ -9062,7 +9557,7 @@  add_ranges_by_labels (dw_die_ref die, co
   offset = add_ranges_num (-(int)in_use - 1);
   if (!*added)
     {
-      add_AT_range_list (die, DW_AT_ranges, offset);
+      add_AT_range_list (die, DW_AT_ranges, offset, force_direct);
       *added = true;
     }
 }
@@ -9599,7 +10094,7 @@  output_one_line_info_table (dw_line_info
    information goes into the .debug_line section.  */
 
 static void
-output_line_info (void)
+output_line_info (bool prologue_only)
 {
   char l1[20], l2[20], p1[20], p2[20];
   int ver = dwarf_version;
@@ -9669,6 +10164,12 @@  output_line_info (void)
   /* Write out the information about the files we use.  */
   output_file_names ();
   ASM_OUTPUT_LABEL (asm_out_file, p2);
+  if (prologue_only)
+    {
+      /* Output the marker for the end of the line number info.  */
+      ASM_OUTPUT_LABEL (asm_out_file, l2);
+      return;
+    }
 
   if (separate_line_info)
     {
@@ -11975,14 +12476,7 @@  mem_loc_descriptor (rtx rtl, enum machin
 	  if (!targetm.have_tls || !targetm.asm_out.output_dwarf_dtprel)
 	    break;
 
-	  /* We used to emit DW_OP_addr here, but that's wrong, since
-	     DW_OP_addr should be relocated by the debug info consumer,
-	     while DW_OP_GNU_push_tls_address operand should not.  */
-	  temp = new_loc_descr (DWARF2_ADDR_SIZE == 4
-				? DW_OP_const4u : DW_OP_const8u, 0, 0);
-	  temp->dw_loc_oprnd1.val_class = dw_val_class_addr;
-	  temp->dw_loc_oprnd1.v.val_addr = rtl;
-	  temp->dtprel = true;
+          temp = new_addr_loc_descr (rtl, true);
 
 	  mem_loc_result = new_loc_descr (DW_OP_GNU_push_tls_address, 0, 0);
 	  add_loc_descr (&mem_loc_result, temp);
@@ -11994,9 +12488,7 @@  mem_loc_descriptor (rtx rtl, enum machin
 	break;
 
     symref:
-      mem_loc_result = new_loc_descr (DW_OP_addr, 0, 0);
-      mem_loc_result->dw_loc_oprnd1.val_class = dw_val_class_addr;
-      mem_loc_result->dw_loc_oprnd1.v.val_addr = rtl;
+      mem_loc_result = new_addr_loc_descr (rtl, 0);
       VEC_safe_push (rtx, gc, used_rtx_array, rtl);
       break;
 
@@ -12898,9 +13390,7 @@  loc_descriptor (rtx rtl, enum machine_mo
       if (mode != VOIDmode && GET_MODE_SIZE (mode) == DWARF2_ADDR_SIZE
 	  && (dwarf_version >= 4 || !dwarf_strict))
 	{
-	  loc_result = new_loc_descr (DW_OP_addr, 0, 0);
-	  loc_result->dw_loc_oprnd1.val_class = dw_val_class_addr;
-	  loc_result->dw_loc_oprnd1.v.val_addr = rtl;
+	  loc_result = new_addr_loc_descr (rtl, 0);
 	  add_loc_descr (&loc_result, new_loc_descr (DW_OP_stack_value, 0, 0));
 	  VEC_safe_push (rtx, gc, used_rtx_array, rtl);
 	}
@@ -13601,8 +14091,7 @@  loc_list_from_tree (tree loc, int want_a
       if (DECL_THREAD_LOCAL_P (loc))
 	{
 	  rtx rtl;
-	  enum dwarf_location_atom first_op;
-	  enum dwarf_location_atom second_op;
+	  enum dwarf_location_atom tls_op;
 	  bool dtprel = false;
 
 	  if (targetm.have_tls)
@@ -13620,9 +14109,8 @@  loc_list_from_tree (tree loc, int want_a
 		  operand shouldn't be.  */
 	      if (DECL_EXTERNAL (loc) && !targetm.binds_local_p (loc))
 		return 0;
-	      first_op = DWARF2_ADDR_SIZE == 4 ? DW_OP_const4u : DW_OP_const8u;
 	      dtprel = true;
-	      second_op = DW_OP_GNU_push_tls_address;
+	      tls_op = DW_OP_GNU_push_tls_address;
 	    }
 	  else
 	    {
@@ -13634,8 +14122,7 @@  loc_list_from_tree (tree loc, int want_a
 		 no longer appear in gimple code.  We used the control
 		 variable in specific so that we could pick it up here.  */
 	      loc = DECL_VALUE_EXPR (loc);
-	      first_op = DW_OP_addr;
-	      second_op = DW_OP_form_tls_address;
+	      tls_op = DW_OP_form_tls_address;
 	    }
 
 	  rtl = rtl_for_decl_location (loc);
@@ -13648,12 +14135,8 @@  loc_list_from_tree (tree loc, int want_a
 	  if (! CONSTANT_P (rtl))
 	    return 0;
 
-	  ret = new_loc_descr (first_op, 0, 0);
-	  ret->dw_loc_oprnd1.val_class = dw_val_class_addr;
-	  ret->dw_loc_oprnd1.v.val_addr = rtl;
-	  ret->dtprel = dtprel;
-
-	  ret1 = new_loc_descr (second_op, 0, 0);
+          ret = new_addr_loc_descr (rtl, dtprel);
+	  ret1 = new_loc_descr (tls_op, 0, 0);
 	  add_loc_descr (&ret, ret1);
 
 	  have_address = 1;
@@ -13698,11 +14181,7 @@  loc_list_from_tree (tree loc, int want_a
 	    return 0;
 	  }
 	else if (CONSTANT_P (rtl) && const_ok_for_output (rtl))
-	  {
-	    ret = new_loc_descr (DW_OP_addr, 0, 0);
-	    ret->dw_loc_oprnd1.val_class = dw_val_class_addr;
-	    ret->dw_loc_oprnd1.v.val_addr = rtl;
-	  }
+          ret = new_addr_loc_descr (rtl, 0);
 	else
 	  {
 	    enum machine_mode mode, mem_mode;
@@ -14640,9 +15119,7 @@  add_const_value_attribute (dw_die_ref di
 	  dw_loc_descr_ref loc_result;
 	  resolve_one_addr (&rtl, NULL);
 	rtl_addr:
-	  loc_result = new_loc_descr (DW_OP_addr, 0, 0);
-	  loc_result->dw_loc_oprnd1.val_class = dw_val_class_addr;
-	  loc_result->dw_loc_oprnd1.v.val_addr = rtl;
+	  loc_result = new_addr_loc_descr (rtl, 0);
 	  add_loc_descr (&loc_result, new_loc_descr (DW_OP_stack_value, 0, 0));
 	  add_AT_loc (die, DW_AT_location, loc_result);
 	  VEC_safe_push (rtx, gc, used_rtx_array, rtl);
@@ -16151,7 +16628,7 @@  add_name_and_src_coords_attributes (dw_d
   if (TREE_CODE (decl) == FUNCTION_DECL && TREE_ASM_WRITTEN (decl))
     {
       add_AT_addr (die, DW_AT_VMS_rtnbeg_pd_address,
-		   XEXP (DECL_RTL (decl), 0));
+		   XEXP (DECL_RTL (decl), 0), false);
       VEC_safe_push (rtx, gc, used_rtx_array, XEXP (DECL_RTL (decl), 0));
     }
 #endif /* VMS_DEBUGGING_INFO */
@@ -16172,7 +16649,7 @@  dwarf2out_vms_debug_main_pointer (void)
   add_name_attribute (die, VMS_DEBUG_MAIN_POINTER);
   ASM_GENERATE_INTERNAL_LABEL (label, PROLOGUE_END_LABEL,
 			       FUNC_LABEL_ID (cfun));
-  add_AT_lbl_id (die, DW_AT_entry_pc, label);
+  add_AT_lbl_id (die, DW_AT_entry_pc, label, false);
 
   /* Make it the first child of comp_unit_die ().  */
   die->die_parent = comp_unit_die ();
@@ -16759,7 +17236,7 @@  gen_entry_point_die (tree decl, dw_die_r
   if (DECL_ABSTRACT (decl))
     equate_decl_number_to_die (decl, decl_die);
   else
-    add_AT_lbl_id (decl_die, DW_AT_low_pc, decl_start_label (decl));
+    add_AT_lbl_id (decl_die, DW_AT_low_pc, decl_start_label (decl), false);
 }
 #endif
 
@@ -17280,7 +17757,7 @@  gen_call_site_die (tree decl, dw_die_ref
   if (stmt_die == NULL)
     stmt_die = subr_die;
   die = new_die (DW_TAG_GNU_call_site, stmt_die, NULL_TREE);
-  add_AT_lbl_id (die, DW_AT_low_pc, ca_loc->label);
+  add_AT_lbl_id (die, DW_AT_low_pc, ca_loc->label, false);
   if (ca_loc->tail_call_p)
     add_AT_flag (die, DW_AT_GNU_tail_call, 1);
   if (ca_loc->symbol_ref)
@@ -17289,7 +17766,7 @@  gen_call_site_die (tree decl, dw_die_ref
       if (tdie)
 	add_AT_die_ref (die, DW_AT_abstract_origin, tdie);
       else
-	add_AT_addr (die, DW_AT_abstract_origin, ca_loc->symbol_ref);
+	add_AT_addr (die, DW_AT_abstract_origin, ca_loc->symbol_ref, false);
     }
   return die;
 }
@@ -17480,8 +17957,8 @@  gen_subprogram_die (tree decl, dw_die_re
 	  if (fde->dw_fde_begin)
 	    {
 	      /* We have already generated the labels.  */
-	      add_AT_lbl_id (subr_die, DW_AT_low_pc, fde->dw_fde_begin);
-	      add_AT_lbl_id (subr_die, DW_AT_high_pc, fde->dw_fde_end);
+	      add_AT_lbl_id (subr_die, DW_AT_low_pc, fde->dw_fde_begin, false);
+	      add_AT_lbl_id (subr_die, DW_AT_high_pc, fde->dw_fde_end, false);
 	    }
 	  else
 	    {
@@ -17489,10 +17966,10 @@  gen_subprogram_die (tree decl, dw_die_re
 	      char label_id[MAX_ARTIFICIAL_LABEL_BYTES];
 	      ASM_GENERATE_INTERNAL_LABEL (label_id, FUNC_BEGIN_LABEL,
 					   FUNC_LABEL_ID (cfun));
-	      add_AT_lbl_id (subr_die, DW_AT_low_pc, label_id);
+	      add_AT_lbl_id (subr_die, DW_AT_low_pc, label_id, false);
 	      ASM_GENERATE_INTERNAL_LABEL (label_id, FUNC_END_LABEL,
 					   FUNC_LABEL_ID (cfun));
-	      add_AT_lbl_id (subr_die, DW_AT_high_pc, label_id);
+	      add_AT_lbl_id (subr_die, DW_AT_high_pc, label_id, false);
 	    }
 
 #if VMS_DEBUGGING_INFO
@@ -17535,10 +18012,11 @@  gen_subprogram_die (tree decl, dw_die_re
 		     alignment offset.  */
 		  bool range_list_added = false;
 		  add_ranges_by_labels (subr_die, fde->dw_fde_begin,
-					fde->dw_fde_end, &range_list_added);
+					fde->dw_fde_end, &range_list_added,
+					false);
 		  add_ranges_by_labels (subr_die, fde->dw_fde_second_begin,
 					fde->dw_fde_second_end,
-					&range_list_added);
+					&range_list_added, false);
 		  if (range_list_added)
 		    add_ranges (NULL);
 		}
@@ -17557,9 +18035,9 @@  gen_subprogram_die (tree decl, dw_die_re
 
 		  /* Do the 'primary' section.   */
 		  add_AT_lbl_id (subr_die, DW_AT_low_pc,
-				 fde->dw_fde_begin);
+				 fde->dw_fde_begin, false);
 		  add_AT_lbl_id (subr_die, DW_AT_high_pc,
-				 fde->dw_fde_end);
+				 fde->dw_fde_end, false);
 
 		  /* Build a minimal DIE for the secondary section.  */
 		  seg_die = new_die (DW_TAG_subprogram,
@@ -17584,9 +18062,9 @@  gen_subprogram_die (tree decl, dw_die_re
 
 		  name = concat ("__second_sect_of_", name, NULL); 
 		  add_AT_lbl_id (seg_die, DW_AT_low_pc,
-				 fde->dw_fde_second_begin);
+				 fde->dw_fde_second_begin, false);
 		  add_AT_lbl_id (seg_die, DW_AT_high_pc,
-				 fde->dw_fde_second_end);
+				 fde->dw_fde_second_end, false);
 		  add_name_attribute (seg_die, name);
 		  if (want_pubnames ())
 		    add_pubname_string (name, seg_die);
@@ -17594,8 +18072,8 @@  gen_subprogram_die (tree decl, dw_die_re
 	    }
 	  else
 	    {
-	      add_AT_lbl_id (subr_die, DW_AT_low_pc, fde->dw_fde_begin);
-	      add_AT_lbl_id (subr_die, DW_AT_high_pc, fde->dw_fde_end);
+	      add_AT_lbl_id (subr_die, DW_AT_low_pc, fde->dw_fde_begin, false);
+	      add_AT_lbl_id (subr_die, DW_AT_high_pc, fde->dw_fde_end, false);
 	    }
 	}
 
@@ -18039,7 +18517,7 @@  gen_variable_die (tree decl, tree origin
 	    {
 	      /* Optimize the common case.  */
 	      if (single_element_loc_list_p (loc)
-		  && loc->expr->dw_loc_opc == DW_OP_addr
+                  && loc->expr->dw_loc_opc == DW_OP_addr
 		  && loc->expr->dw_loc_next == NULL
 		  && GET_CODE (loc->expr->dw_loc_oprnd1.v.val_addr) == SYMBOL_REF)
 		loc->expr->dw_loc_oprnd1.v.val_addr
@@ -18223,7 +18701,7 @@  gen_label_die (tree decl, dw_die_ref con
 	  gcc_assert (!INSN_DELETED_P (insn));
 
 	  ASM_GENERATE_INTERNAL_LABEL (label, "L", CODE_LABEL_NUMBER (insn));
-	  add_AT_lbl_id (lbl_die, DW_AT_low_pc, label);
+	  add_AT_lbl_id (lbl_die, DW_AT_low_pc, label, false);
 	}
       else if (insn
 	       && NOTE_P (insn)
@@ -18231,7 +18709,7 @@  gen_label_die (tree decl, dw_die_ref con
 	       && CODE_LABEL_NUMBER (insn) != -1)
 	{
 	  ASM_GENERATE_INTERNAL_LABEL (label, "LDL", CODE_LABEL_NUMBER (insn));
-	  add_AT_lbl_id (lbl_die, DW_AT_low_pc, label);
+	  add_AT_lbl_id (lbl_die, DW_AT_low_pc, label, false);
 	}
     }
 }
@@ -18270,10 +18748,10 @@  add_high_low_attributes (tree stmt, dw_d
 	{
 	  ASM_GENERATE_INTERNAL_LABEL (label, BLOCK_BEGIN_LABEL,
 				       BLOCK_NUMBER (stmt));
-	  add_AT_lbl_id (die, DW_AT_entry_pc, label);
+	  add_AT_lbl_id (die, DW_AT_entry_pc, label, false);
 	}
 
-      add_AT_range_list (die, DW_AT_ranges, add_ranges (stmt));
+      add_AT_range_list (die, DW_AT_ranges, add_ranges (stmt), false);
 
       chain = BLOCK_FRAGMENT_CHAIN (stmt);
       do
@@ -18288,10 +18766,10 @@  add_high_low_attributes (tree stmt, dw_d
     {
       ASM_GENERATE_INTERNAL_LABEL (label, BLOCK_BEGIN_LABEL,
 				   BLOCK_NUMBER (stmt));
-      add_AT_lbl_id (die, DW_AT_low_pc, label);
+      add_AT_lbl_id (die, DW_AT_low_pc, label, false);
       ASM_GENERATE_INTERNAL_LABEL (label, BLOCK_END_LABEL,
 				   BLOCK_NUMBER (stmt));
-      add_AT_lbl_id (die, DW_AT_high_pc, label);
+      add_AT_lbl_id (die, DW_AT_high_pc, label, false);
     }
 }
 
@@ -20943,6 +21421,7 @@  output_macinfo_op (macinfo_entry *ref)
     case DW_MACRO_GNU_define_indirect:
     case DW_MACRO_GNU_undef_indirect:
       node = find_AT_string (ref->info);
+      /* FIXME: needs to change for dwarf_split_debug_info.  */
       if (node->form != DW_FORM_strp)
 	{
 	  char label[32];
@@ -21130,8 +21609,10 @@  output_macinfo (void)
 	dw2_asm_output_data (1, 3, "Flags: 64-bit, lineptr present");
       else
 	dw2_asm_output_data (1, 2, "Flags: 32-bit, lineptr present");
-      dw2_asm_output_offset (DWARF_OFFSET_SIZE, debug_line_section_label,
-			     debug_line_section, NULL);
+      dw2_asm_output_offset (DWARF_OFFSET_SIZE,
+                             (!dwarf_split_debug_info ? debug_line_section_label
+                              : debug_skeleton_line_section_label),
+                             debug_line_section, NULL);
     }
 
   /* In the first loop, it emits the primary .debug_macinfo section
@@ -21270,26 +21751,60 @@  dwarf2out_init (const char *filename ATT
 
   used_rtx_array = VEC_alloc (rtx, gc, 32);
 
-  debug_info_section = get_section (DEBUG_INFO_SECTION,
-				    SECTION_DEBUG, NULL);
-  debug_abbrev_section = get_section (DEBUG_ABBREV_SECTION,
-				      SECTION_DEBUG, NULL);
+  if (!dwarf_split_debug_info)
+    {
+      debug_info_section = get_section (DEBUG_INFO_SECTION,
+                                        SECTION_DEBUG, NULL);
+      debug_abbrev_section = get_section (DEBUG_ABBREV_SECTION,
+                                          SECTION_DEBUG, NULL);
+      debug_loc_section = get_section (DEBUG_LOC_SECTION,
+                                       SECTION_DEBUG, NULL);
+    }
+  else
+    {
+      debug_info_section = get_section (DEBUG_DWO_INFO_SECTION,
+                                        SECTION_DEBUG | SECTION_EXCLUDE, NULL);
+      debug_abbrev_section = get_section (DEBUG_DWO_ABBREV_SECTION,
+                                          SECTION_DEBUG | SECTION_EXCLUDE,
+                                          NULL);
+      debug_addr_section = get_section (DEBUG_ADDR_SECTION,
+                                        SECTION_DEBUG, NULL);
+      debug_skeleton_info_section = get_section (DEBUG_INFO_SECTION,
+                                                 SECTION_DEBUG, NULL);
+      debug_skeleton_abbrev_section = get_section (DEBUG_ABBREV_SECTION,
+                                                   SECTION_DEBUG, NULL);
+      ASM_GENERATE_INTERNAL_LABEL (debug_skeleton_abbrev_section_label,
+				   DEBUG_SKELETON_ABBREV_SECTION_LABEL, 0);
+
+      /* Somewhat confusing detail: The skeleton_[abbrev|info] sections stay in
+         the main .o, but the skeleton_line goes into the split off dwo.  */
+      debug_skeleton_line_section
+          = get_section (DEBUG_DWO_LINE_SECTION,
+                         SECTION_DEBUG | SECTION_EXCLUDE, NULL);
+      ASM_GENERATE_INTERNAL_LABEL (debug_skeleton_line_section_label,
+                                   DEBUG_SKELETON_LINE_SECTION_LABEL, 0);
+      debug_str_offsets_section = get_section (DEBUG_STR_OFFSETS_SECTION,
+                                               SECTION_DEBUG | SECTION_EXCLUDE,
+                                               NULL);
+      ASM_GENERATE_INTERNAL_LABEL (debug_skeleton_info_section_label,
+                                   DEBUG_SKELETON_INFO_SECTION_LABEL, 0);
+      debug_loc_section = get_section (DEBUG_DWO_LOC_SECTION,
+                                       SECTION_DEBUG | SECTION_EXCLUDE, NULL);
+    }
   debug_aranges_section = get_section (DEBUG_ARANGES_SECTION,
 				       SECTION_DEBUG, NULL);
   debug_macinfo_section = get_section (dwarf_strict
 				       ? DEBUG_MACINFO_SECTION
 				       : DEBUG_MACRO_SECTION,
-				       SECTION_DEBUG, NULL);
+				       DEBUG_MACRO_SECTION_FLAGS, NULL);
   debug_line_section = get_section (DEBUG_LINE_SECTION,
 				    SECTION_DEBUG, NULL);
-  debug_loc_section = get_section (DEBUG_LOC_SECTION,
-				   SECTION_DEBUG, NULL);
   debug_pubnames_section = get_section (DEBUG_PUBNAMES_SECTION,
 					SECTION_DEBUG, NULL);
   debug_pubtypes_section = get_section (DEBUG_PUBTYPES_SECTION,
 					SECTION_DEBUG, NULL);
   debug_str_section = get_section (DEBUG_STR_SECTION,
-				   DEBUG_STR_SECTION_FLAGS, NULL);
+                                   DEBUG_STR_SECTION_FLAGS, NULL);
   debug_ranges_section = get_section (DEBUG_RANGES_SECTION,
 				      SECTION_DEBUG, NULL);
   debug_frame_section = get_section (DEBUG_FRAME_SECTION,
@@ -21313,10 +21828,13 @@  dwarf2out_init (const char *filename ATT
 			       DEBUG_LINE_SECTION_LABEL, 0);
   ASM_GENERATE_INTERNAL_LABEL (ranges_section_label,
 			       DEBUG_RANGES_SECTION_LABEL, 0);
+  ASM_GENERATE_INTERNAL_LABEL (debug_addr_section_label,
+			       DEBUG_ADDR_SECTION_LABEL, 0);
   ASM_GENERATE_INTERNAL_LABEL (macinfo_section_label,
 			       dwarf_strict
 			       ? DEBUG_MACINFO_SECTION_LABEL
 			       : DEBUG_MACRO_SECTION_LABEL, 0);
+  ASM_GENERATE_INTERNAL_LABEL (loc_section_label, DEBUG_LOC_SECTION_LABEL, 0);
 
   if (debug_info_level >= DINFO_LEVEL_VERBOSE)
     macinfo_table = VEC_alloc (macinfo_entry, gc, 64);
@@ -21360,6 +21878,79 @@  output_indirect_string (void **h, void *
   return 1;
 }
 
+static void
+output_index_strings (void)
+{
+  unsigned int i;
+  unsigned int len = 0;
+  struct indirect_string_node *node;
+
+  if (VEC_empty (indirect_string_node, index_string_table))
+    return;
+
+  switch_to_section (debug_str_offsets_section);
+  for (i = 0; VEC_iterate (indirect_string_node, index_string_table, i, node);
+       i++)
+    {
+      gcc_assert (node->form == DW_FORM_GNU_str_index);
+      dw2_asm_output_data (DWARF_OFFSET_SIZE, len,
+                           "indexed string 0x%x: %s", i, node->str);
+      len += strlen (node->str) + 1;
+    }
+  switch_to_section (debug_str_section);
+  for (i = 0; VEC_iterate (indirect_string_node, index_string_table, i, node);
+       i++)
+    {
+      ASM_OUTPUT_LABEL (asm_out_file, node->label);
+      assemble_string (node->str, strlen (node->str) + 1);
+    }
+}
+
+/* Write the index table.  */
+
+static void
+output_addr_table (void)
+{
+  unsigned int i;
+  dw_attr_node *node;
+
+  if (VEC_empty (dw_attr_node, addr_index_table))
+    return;
+
+  switch_to_section (debug_addr_section);
+  for (i = 0; VEC_iterate (dw_attr_node, addr_index_table, i, node); i++)
+    {
+      const char *name;
+
+      if (node->dw_attr == 0)
+	{
+	  dw2_asm_output_data (DWARF2_ADDR_SIZE, 0, "<Removed entry>");
+	  continue;
+	}
+
+      name = dwarf_attr_name (node->dw_attr);
+      switch (AT_class (node))
+        {
+          case dw_val_class_addr:
+            dw2_asm_output_addr_rtx (DWARF2_ADDR_SIZE, AT_addr (node),
+                                     "%s", name);
+            break;
+          case dw_val_class_loc:
+            gcc_assert (targetm.asm_out.output_dwarf_dtprel);
+            targetm.asm_out.output_dwarf_dtprel (asm_out_file,
+                                                 DWARF2_ADDR_SIZE,
+                                                 node->dw_attr_val.v.val_addr);
+            fputc ('\n', asm_out_file);
+            break;
+          case dw_val_class_lbl_id:
+            dw2_asm_output_addr (DWARF2_ADDR_SIZE, AT_lbl (node), "%s", name);
+            break;
+          default:
+            gcc_unreachable ();
+        }
+    }
+}
+
 #if ENABLE_ASSERT_CHECKING
 /* Verify that all marks are clear.  */
 
@@ -21964,6 +22555,17 @@  resolve_addr_in_expr (dw_loc_descr_ref l
 	if (resolve_one_addr (&loc->dw_loc_oprnd1.v.val_addr, NULL))
 	  return false;
 	break;
+      case DW_OP_GNU_addr_index:
+      case DW_OP_GNU_const_index:
+        {
+          unsigned int idx = loc->dw_loc_oprnd1.val_index;
+          dw_attr_node *node = VEC_index (dw_attr_node, addr_index_table, idx);
+          if ((loc->dw_loc_opc == DW_OP_GNU_addr_index
+               || (loc->dw_loc_opc == DW_OP_GNU_const_index && loc->dtprel))
+              && resolve_one_addr (&node->dw_attr_val.v.val_addr, NULL))
+            return false;
+        }
+	break;
       case DW_OP_const4u:
       case DW_OP_const8u:
 	if (loc->dtprel
@@ -22098,11 +22700,15 @@  resolve_addr (dw_die_ref die)
 		if (!resolve_addr_in_expr ((*curr)->expr))
 		  {
 		    dw_loc_list_ref next = (*curr)->dw_loc_next;
+		    dw_loc_descr_ref l = (*curr)->expr;
+
 		    if (next && (*curr)->ll_symbol)
 		      {
 			gcc_assert (!next->ll_symbol);
 			next->ll_symbol = (*curr)->ll_symbol;
 		      }
+		    if (l->dw_loc_oprnd1.val_index != -1U)
+		      remove_addr_table_entry (l->dw_loc_oprnd1.val_index);
 		    *curr = next;
 		  }
 		else
@@ -22116,6 +22722,8 @@  resolve_addr (dw_die_ref die)
 	    else
 	      {
 		loc->replaced = 1;
+                if (dwarf_split_debug_info)
+                  remove_loc_list_addr_table_entries (loc);
 		loc->dw_loc_next = *start;
 	      }
 	  }
@@ -22140,6 +22748,8 @@  resolve_addr (dw_die_ref die)
 	       || l->dw_loc_next != NULL)
 	      && !resolve_addr_in_expr (l))
 	    {
+	      if (l->dw_loc_oprnd1.val_index != -1U)
+		remove_addr_table_entry (l->dw_loc_oprnd1.val_index);
 	      remove_AT (die, a->dw_attr);
 	      ix--;
 	    }
@@ -22151,6 +22761,8 @@  resolve_addr (dw_die_ref die)
 	if (a->dw_attr == DW_AT_const_value
 	    && resolve_one_addr (&a->dw_attr_val.v.val_addr, NULL))
 	  {
+	    if (AT_index (a) != -1U)
+	      remove_addr_table_entry (AT_index (a));
 	    remove_AT (die, a->dw_attr);
 	    ix--;
 	  }
@@ -22174,6 +22786,8 @@  resolve_addr (dw_die_ref die)
 	      }
 	    else
 	      {
+		if (AT_index (a) != -1U)
+		  remove_addr_table_entry (AT_index (a));
 		remove_AT (die, a->dw_attr);
 		ix--;
 	      }
@@ -22307,6 +22921,19 @@  hash_loc_operands (dw_loc_descr_ref loc,
 	}
       hash = iterative_hash_rtx (val1->v.val_addr, hash);
       break;
+    case DW_OP_GNU_addr_index:
+    case DW_OP_GNU_const_index:
+      {
+        dw_attr_ref attr = VEC_index (dw_attr_node, addr_index_table,
+                                      val1->val_index);
+        if (loc->dtprel)
+	  {
+            unsigned char dtprel = 0xd1;
+            hash = iterative_hash_object (dtprel, hash);
+          }
+        hash = iterative_hash_rtx (attr->dw_attr_val.v.val_addr, hash);
+      }
+      break;
     case DW_OP_GNU_implicit_pointer:
       hash = iterative_hash_object (val2->v.val_int, hash);
       break;
@@ -22488,9 +23115,12 @@  compare_loc_operands (dw_loc_descr_ref x
       return valx1->v.val_int == valy1->v.val_int;
     case DW_OP_skip:
     case DW_OP_bra:
+      /* If splitting debug info, the use of DW_OP_GNU_addr_index
+	 can cause irrelevant differences in dw_loc_addr.  */
       gcc_assert (valx1->val_class == dw_val_class_loc
 		  && valy1->val_class == dw_val_class_loc
-		  && x->dw_loc_addr == y->dw_loc_addr);
+		  && (dwarf_split_debug_info
+		      || x->dw_loc_addr == y->dw_loc_addr));
       return valx1->v.val_loc->dw_loc_addr == valy1->v.val_loc->dw_loc_addr;
     case DW_OP_implicit_value:
       if (valx1->v.val_unsigned != valy1->v.val_unsigned
@@ -22521,6 +23151,18 @@  compare_loc_operands (dw_loc_descr_ref x
     case DW_OP_addr:
     hash_addr:
       return rtx_equal_p (valx1->v.val_addr, valy1->v.val_addr);
+    case DW_OP_GNU_addr_index:
+    case DW_OP_GNU_const_index:
+      {
+        dw_attr_node *attrx1 = VEC_index (dw_attr_node,
+                                          addr_index_table,
+                                          valx1->val_index);
+        dw_attr_node *attry1 = VEC_index (dw_attr_node,
+                                          addr_index_table,
+                                          valy1->val_index);
+        return rtx_equal_p (attrx1->dw_attr_val.v.val_addr,
+                            attry1->dw_attr_val.v.val_addr);
+      }
     case DW_OP_GNU_implicit_pointer:
       return valx1->val_class == dw_val_class_die_ref
 	     && valx1->val_class == valy1->val_class
@@ -22634,7 +23276,7 @@  optimize_location_lists_1 (dw_die_ref di
 	if (*slot == NULL)
 	  *slot = (void *) list;
 	else
-	  a->dw_attr_val.v.val_loc_list = (dw_loc_list_ref) *slot;
+          a->dw_attr_val.v.val_loc_list = (dw_loc_list_ref) *slot;
       }
 
   FOR_EACH_CHILD (die, c, optimize_location_lists_1 (c, htab));
@@ -22650,6 +23292,43 @@  optimize_location_lists (dw_die_ref die)
   optimize_location_lists_1 (die, htab);
   htab_delete (htab);
 }
+
+
+/* Recursively assign each location list a unique index into the debug_addr
+   section.  */
+
+static void
+index_location_lists (dw_die_ref die)
+{
+  dw_die_ref c;
+  dw_attr_ref a;
+  unsigned ix;
+
+  FOR_EACH_VEC_ELT (dw_attr_node, die->die_attr, ix, a)
+    if (AT_class (a) == dw_val_class_loc_list)
+      {
+        dw_loc_list_ref list = AT_loc_list (a);
+        dw_loc_list_ref curr;
+        for (curr = list; curr != NULL; curr = curr->dw_loc_next)
+          {
+            dw_attr_node attr;
+
+            /* Don't index an entry that has already been indexed
+	       or won't be output.  */
+            if (curr->begin_index != -1U
+	        || (strcmp (curr->begin, curr->end) == 0 && !curr->force))
+	      continue;
+
+            attr.dw_attr = DW_AT_location;
+            attr.dw_attr_val.val_class = dw_val_class_lbl_id;
+            attr.dw_attr_val.val_index = -1U;
+            attr.dw_attr_val.v.val_lbl_id = xstrdup (curr->begin);
+            curr->begin_index = add_addr_table_entry (&attr);
+          }
+      }
+
+  FOR_EACH_CHILD (die, c, index_location_lists (c));
+}
 
 /* Output stuff that dwarf requires at the end of every file,
    and generate the DWARF-2 debugging info.  */
@@ -22661,6 +23340,7 @@  dwarf2out_finish (const char *filename)
   comdat_type_node *ctnode;
   htab_t comdat_type_table;
   unsigned int i;
+  dw_die_ref main_comp_unit_die;
 
   /* PCH might result in DW_AT_producer string being restored from the
      header compilation, fix it up if needed.  */
@@ -22814,6 +23494,14 @@  dwarf2out_finish (const char *filename)
   for (ctnode = comdat_type_list; ctnode != NULL; ctnode = ctnode->next)
     add_sibling_attributes (ctnode->root_die);
 
+  /* When splitting DWARF info, we put some attributes in the
+     skeleton compile_unit DIE that remains in the .o, while
+     most attributes go in the DWO compile_unit_die.  */
+  if (dwarf_split_debug_info)
+    main_comp_unit_die = gen_compile_unit_die (NULL);
+  else
+    main_comp_unit_die = comp_unit_die ();
+
   /* Output a terminator label for the .text section.  */
   switch_to_section (text_section);
   targetm.asm_out.internal_label (asm_out_file, TEXT_END_LABEL, 0);
@@ -22831,8 +23519,10 @@  dwarf2out_finish (const char *filename)
       /* Don't add if the CU has no associated code.  */
       if (text_section_used)
 	{
-	  add_AT_lbl_id (comp_unit_die (), DW_AT_low_pc, text_section_label);
-	  add_AT_lbl_id (comp_unit_die (), DW_AT_high_pc, text_end_label);
+	  add_AT_lbl_id (main_comp_unit_die, DW_AT_low_pc, text_section_label,
+			 true);
+	  add_AT_lbl_id (main_comp_unit_die, DW_AT_high_pc, text_end_label,
+			 true);
 	}
     }
   else
@@ -22842,20 +23532,22 @@  dwarf2out_finish (const char *filename)
       bool range_list_added = false;
 
       if (text_section_used)
-	add_ranges_by_labels (comp_unit_die (), text_section_label,
-			      text_end_label, &range_list_added);
+	add_ranges_by_labels (main_comp_unit_die, text_section_label,
+			      text_end_label, &range_list_added, true);
       if (cold_text_section_used)
-	add_ranges_by_labels (comp_unit_die (), cold_text_section_label,
-			      cold_end_label, &range_list_added);
+	add_ranges_by_labels (main_comp_unit_die, cold_text_section_label,
+			      cold_end_label, &range_list_added, true);
 
       FOR_EACH_VEC_ELT (dw_fde_ref, fde_vec, fde_idx, fde)
 	{
 	  if (!fde->in_std_section)
-	    add_ranges_by_labels (comp_unit_die (), fde->dw_fde_begin,
-				  fde->dw_fde_end, &range_list_added);
+	    add_ranges_by_labels (main_comp_unit_die, fde->dw_fde_begin,
+				  fde->dw_fde_end, &range_list_added,
+				  true);
 	  if (fde->dw_fde_second_begin && !fde->second_in_std_section)
-	    add_ranges_by_labels (comp_unit_die (), fde->dw_fde_second_begin,
-				  fde->dw_fde_second_end, &range_list_added);
+	    add_ranges_by_labels (main_comp_unit_die, fde->dw_fde_second_begin,
+				  fde->dw_fde_second_end, &range_list_added,
+				  true);
 	}
 
       if (range_list_added)
@@ -22865,16 +23557,16 @@  dwarf2out_finish (const char *filename)
 	     absolute.  Historically, we've emitted the unexpected
 	     DW_AT_entry_pc instead of DW_AT_low_pc for this purpose.
 	     Emit both to give time for other tools to adapt.  */
-	  add_AT_addr (comp_unit_die (), DW_AT_low_pc, const0_rtx);
+	  add_AT_addr (main_comp_unit_die, DW_AT_low_pc, const0_rtx, true);
 	  if (! dwarf_strict && dwarf_version < 4)
-	    add_AT_addr (comp_unit_die (), DW_AT_entry_pc, const0_rtx);
+	    add_AT_addr (main_comp_unit_die, DW_AT_entry_pc, const0_rtx, true);
 
 	  add_ranges (NULL);
 	}
     }
 
   if (generate_debug_line_table)
-    add_AT_lineptr (comp_unit_die (), DW_AT_stmt_list,
+    add_AT_lineptr (main_comp_unit_die, DW_AT_stmt_list,
 		    debug_line_section_label);
 
   if (have_macinfo)
@@ -22883,7 +23575,11 @@  dwarf2out_finish (const char *filename)
 		   macinfo_section_label);
 
   if (have_location_lists)
-    optimize_location_lists (comp_unit_die ());
+    {
+      optimize_location_lists (comp_unit_die ());
+      if (dwarf_split_debug_info)
+        index_location_lists (comp_unit_die ());
+    }
 
   /* Output all of the compilation units.  We put the main one last so that
      the offsets are available to output_pubnames.  */
@@ -22904,19 +23600,34 @@  dwarf2out_finish (const char *filename)
          attributes.  */
       if (generate_debug_line_table)
         add_AT_lineptr (ctnode->root_die, DW_AT_stmt_list,
-		        debug_line_section_label);
+                        (!dwarf_split_debug_info
+                         ? debug_line_section_label
+                         : debug_skeleton_line_section_label));
 
       output_comdat_type_unit (ctnode);
       *slot = ctnode;
     }
   htab_delete (comdat_type_table);
 
-  add_AT_pubnames (comp_unit_die ());
+  if (!dwarf_split_debug_info)
+    add_AT_pubnames (comp_unit_die ());
+
+  if (dwarf_split_debug_info)
+    {
+      /* Add a place-holder for the dwo_id to the comp-unit die.  */
+      add_AT_data8 (comp_unit_die (), DW_AT_GNU_dwo_id, dwo_id_placeholder);
+      if (ranges_table_in_use)
+	add_AT_lineptr (main_comp_unit_die, DW_AT_GNU_ranges_base,
+			ranges_section_label);
+    }
 
   /* Output the main compilation unit if non-empty or if .debug_macinfo
      or .debug_macro will be emitted.  */
   output_comp_unit (comp_unit_die (), have_macinfo);
 
+  if (dwarf_split_debug_info && info_section_emitted)
+    output_skeleton_debug_sections (main_comp_unit_die);
+
   /* Output the abbreviation table.  */
   if (abbrev_die_table_in_use != 1)
     {
@@ -22930,8 +23641,6 @@  dwarf2out_finish (const char *filename)
     {
       /* Output the location lists info.  */
       switch_to_section (debug_loc_section);
-      ASM_GENERATE_INTERNAL_LABEL (loc_section_label,
-				   DEBUG_LOC_SECTION_LABEL, 0);
       ASM_OUTPUT_LABEL (asm_out_file, loc_section_label);
       output_location_lists (comp_unit_die ());
     }
@@ -22982,10 +23691,22 @@  dwarf2out_finish (const char *filename)
   switch_to_section (debug_line_section);
   ASM_OUTPUT_LABEL (asm_out_file, debug_line_section_label);
   if (! DWARF2_ASM_LINE_DEBUG_INFO)
-    output_line_info ();
+    output_line_info (false);
+
+  if (dwarf_split_debug_info && info_section_emitted)
+    {
+      switch_to_section (debug_skeleton_line_section);
+      ASM_OUTPUT_LABEL (asm_out_file, debug_skeleton_line_section_label);
+      output_line_info (true);
+
+      output_index_strings ();
+
+      switch_to_section (debug_addr_section);
+      ASM_OUTPUT_LABEL (asm_out_file, debug_addr_section_label);
+      output_addr_table ();
+    }
 
-  /* If we emitted any DW_FORM_strp form attribute, output the string
-     table too.  */
+  /* If we emitted any indirect strings, output the string table too.  */
   if (debug_str_hash)
     htab_traverse (debug_str_hash, output_indirect_string, NULL);
 }
Index: gcc/dwarf2out.h
===================================================================
--- gcc/dwarf2out.h	(revision 189829)
+++ gcc/dwarf2out.h	(working copy)
@@ -171,6 +171,7 @@  dw_vec_const;
 
 typedef struct GTY(()) dw_val_struct {
   enum dw_val_class val_class;
+  unsigned int val_index;
   union dw_val_struct_union
     {
       rtx GTY ((tag ("dw_val_class_addr"))) val_addr;
Index: gcc/opts.c
===================================================================
--- gcc/opts.c	(revision 189829)
+++ gcc/opts.c	(working copy)
@@ -865,6 +865,10 @@  finish_options (struct gcc_options *opts
   /* Turn on -ffunction-sections when -freorder-functions=* is used.  */
   if (opts->x_flag_reorder_functions > 1)
     opts->x_flag_function_sections = 1;
+
+  /* The -gsplit-dwarf option requires -gpubnames.  */
+  if (opts->x_dwarf_split_debug_info)
+    opts->x_debug_generate_pub_sections = 1;
 }
 
 #define LEFT_COLUMN	27
@@ -1776,6 +1780,11 @@  common_handle_option (struct gcc_options
       set_debug_level (DWARF2_DEBUG, false, "", opts, opts_set, loc);
       break;
 
+    case OPT_gsplit_dwarf:
+      set_debug_level (NO_DEBUG, DEFAULT_GDB_EXTENSIONS, "", opts, opts_set,
+		       loc);
+      break;
+
     case OPT_ggdb:
       set_debug_level (NO_DEBUG, 2, arg, opts, opts_set, loc);
       break;
Index: gcc/common.opt
===================================================================
--- gcc/common.opt	(revision 189829)
+++ gcc/common.opt	(working copy)
@@ -2432,6 +2432,14 @@  grecord-gcc-switches
 Common RejectNegative Var(dwarf_record_gcc_switches,1)
 Record gcc command line switches in DWARF DW_AT_producer.
 
+gno-split-dwarf
+Common Driver RejectNegative Var(dwarf_split_debug_info,0) Init(0)
+Don't generate debug information in separate .dwo files
+
+gsplit-dwarf
+Common Driver RejectNegative Var(dwarf_split_debug_info,1)
+Generate debug information in separate .dwo files
+
 gstabs
 Common JoinedOrMissing Negative(gstabs+)
 Generate debug information in STABS format