Patchwork [google/4.6] Fix problems with -gfission (issue5844043)

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Submitter Cary Coutant
Date March 16, 2012, 2:07 a.m.
Message ID <20120316020700.3203DE0482@ccoutant.mtv.corp.google.com>
Download mbox | patch
Permalink /patch/147128/
State New
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Comments

Cary Coutant - March 16, 2012, 2:07 a.m.
For google/gcc-4_6 branch.

This patch fixes several problems with -gfission:
 - Bad index for range list in the compile unit DIE.
 - DW_AT_ranges attribute for compile unit in the wrong file.
 - Incorrect size for skeleton type unit DIEs.
 - Wrote location expression using DW_OP_addr to DWO file.
 - Emitted skeleton debug section even when there is no debug info.

Tested: bootstrap, gcc regression tests, hand testing on -gfission
test cases.


include/

2012-03-15   Sterling Augustine  <saugustine@google.com>
	     Cary Coutant  <ccoutant@google.com>

	* dwarf2.h (enum dwarf_location_atom): Add
	DW_OP_GNU_addr_index.

gcc/

2012-03-15   Sterling Augustine  <saugustine@google.com>
	     Cary Coutant  <ccoutant@google.com>

	* dwarf2out.c (dwarf_stack_op_name): Add DW_OP_GNU_addr_index.
	(size_of_loc_descr): Likewise.
	(output_loc_operands): Likewise.
	(output_loc_operands_raw): Likewise.
	(new_addr_loc_descr): New function.
	(add_AT_range_list): Store index in AT_index.
	(size_of_die): For range_list, use AT_index for index value.
	(add_top_level_skeleton_die_attrs): Don't add DW_AT_stmt_list here.
	(get_skeleton_type_unit): New function.
	(output_skeleton_debug_sections): Add comp_unit parameter; adjust
	caller.  Don't allocate new comp unit DIE here.  Move allocation
	of debug_skeleton_info_section_label and
	debug_skeleton_abbrev_section_label to dwarf2out_init.  Call
	get_skeleton_type_unit.
	(output_comdat_type_unit): Remove assert; call get_skeleton_type_unit.
	(mem_loc_descriptor): Call new_addr_loc_desc.
	(loc_descriptor): Likewise.
	(loc_list_from_tree): Likewise.
	(add_const_value_attribute): Likewise.
	(dwarf2out_init): Allocate debug_skeleton_info_section_label and
	debug_skeleton_abbrev_section_label.
	(output_indirect_string): Check for DW_FORM_strp instead of label
	and refcount.
	(output_addr_table): Add case for dw_val_class_loc.
	(resolve_addr_in_expr): Handle DW_OP_addr_index.
	(hash_loc_operands): Likewise.
	(compare_loc_operands): Likewise.
	(dwarf2out_finish): Allocate skeleton compile unit DIE here; add
	range lists, DW_AT_stmt_list, and DW_AT_macro_info to it instead
	of dwo compile unit DIE.  Output skeleton debug info section only
	if there is debug info.



--
This patch is available for review at http://codereview.appspot.com/5844043

Patch

Index: include/dwarf2.h
===================================================================
--- include/dwarf2.h	(revision 185451)
+++ include/dwarf2.h	(working copy)
@@ -547,6 +547,8 @@  enum dwarf_location_atom
     DW_OP_GNU_uninit     = 0xf0,
     DW_OP_GNU_encoded_addr = 0xf1,
     DW_OP_GNU_implicit_pointer = 0xf2,
+    /* Extension for Fission.  See http://gcc.gnu.org/wiki/DebugFission.  */
+    DW_OP_GNU_addr_index = 0xfb,
     /* HP extensions.  */
     DW_OP_HP_unknown     = 0xe0, /* Ouch, the same as GNU_push_tls_address.  */
     DW_OP_HP_is_value    = 0xe1,
Index: gcc/dwarf2out.c
===================================================================
--- gcc/dwarf2out.c	(revision 185451)
+++ gcc/dwarf2out.c	(working copy)
@@ -4779,6 +4779,8 @@  dwarf_stack_op_name (unsigned int op)
       return "DW_OP_GNU_encoded_addr";
     case DW_OP_GNU_implicit_pointer:
       return "DW_OP_GNU_implicit_pointer";
+    case DW_OP_GNU_addr_index:
+      return "DW_OP_GNU_addr_index";
 
     default:
       return "OP_<unknown>";
@@ -4897,6 +4899,9 @@  size_of_loc_descr (dw_loc_descr_ref loc)
     case DW_OP_addr:
       size += DWARF2_ADDR_SIZE;
       break;
+    case DW_OP_GNU_addr_index:
+      size += size_of_uleb128 (loc->dw_loc_oprnd1.v.val_unsigned);
+      break;
     case DW_OP_const1u:
     case DW_OP_const1s:
       size += 1;
@@ -5275,6 +5280,11 @@  output_loc_operands (dw_loc_descr_ref lo
 	}
       break;
 
+    case DW_OP_GNU_addr_index:
+      dw2_asm_output_data_uleb128 (loc->dw_loc_oprnd1.v.val_unsigned,
+                                   "(address index)");
+      break;
+
     case DW_OP_GNU_implicit_pointer:
       {
 	char label[MAX_ARTIFICIAL_LABEL_BYTES
@@ -5343,6 +5353,7 @@  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_implicit_value:
       /* We cannot output addresses in .cfi_escape, only bytes.  */
       gcc_unreachable ();
@@ -6314,6 +6325,7 @@  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 unsigned int add_addr_table_entry (dw_attr_node *);
 static void add_AT_addr (dw_die_ref, enum dwarf_attribute, rtx);
 static inline rtx AT_addr (dw_attr_ref);
 static void add_AT_lbl_id (dw_die_ref, enum dwarf_attribute, const char *);
@@ -6571,6 +6583,31 @@  static bool generic_type_p (tree);
 static void schedule_generic_params_dies_gen (tree t);
 static void gen_scheduled_generic_parms_dies (void);
 
+/* 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_OP_addr, 0, 0);
+
+  ref->dw_loc_oprnd1.val_class = dw_val_class_addr;
+  ref->dw_loc_oprnd1.v.val_addr = addr;
+  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.v.val_addr = addr;
+
+      ref->dw_loc_opc = DW_OP_GNU_addr_index;
+      ref->dw_loc_oprnd1.v.val_unsigned = add_addr_table_entry (&attr);
+    }
+  return ref;
+}
+
 /* Section names used to hold DWARF debugging information.  */
 
 #ifndef DEBUG_INFO_SECTION
@@ -7358,7 +7395,7 @@  AT_class (dw_attr_ref a)
 }
 
 /* Return the index for any attribute that will be referenced with a
-   DW_FORM_GNU_ref_index of DW_FORM_GNU_addr_index.  Strings have their
+   DW_FORM_GNU_ref_index or DW_FORM_GNU_addr_index.  Strings have their
    indices handled differently to account for reference counting
    pruning.  */
 
@@ -7372,7 +7409,7 @@  AT_index (dw_attr_ref a)
 }
 
 /* Set the index for any attribute that will be referenced with a
-   DW_FORM_GNU_ref_index of DW_FORM_GNU_addr_index.  */
+   DW_FORM_GNU_ref_index or DW_FORM_GNU_addr_index.  */
 
 static inline void
 set_AT_index (dw_attr_ref a, unsigned int index)
@@ -7905,7 +7942,7 @@  add_ref_table_entry (dw_attr_node *attr)
   return 0;
 }
 
-/* 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,
@@ -7919,11 +7956,12 @@  add_AT_range_list (dw_die_ref die, enum 
   add_dwarf_attr (die, &attr);
   if (dwarf_split_debug_info)
     {
+      dw_attr_ref a = get_AT (die, DW_AT_ranges);
+
       /* There will be two copies of the attr, one in the die, and one in the
-         ref table. Substitute the index for the actual offset in the die, and
-         save the actual offset in the ref table.  */
-      get_AT (die, DW_AT_ranges)->dw_attr_val.v.val_offset
-          = add_ref_table_entry (&attr);
+         ref table. Store the index in the die, and save the actual offset
+         in the ref table.  */
+      set_AT_index (a, add_ref_table_entry (&attr));
     }
 }
 
@@ -10901,14 +10939,9 @@  size_of_die (dw_die_ref die)
 	  }
 	  break;
 	case dw_val_class_loc_list:
-          if (dwarf_split_debug_info)
-            size += size_of_uleb128 (AT_index (a));
-          else
-            size += DWARF_OFFSET_SIZE;
-	  break;
 	case dw_val_class_range_list:
           if (dwarf_split_debug_info)
-            size += size_of_uleb128 (a->dw_attr_val.v.val_offset);
+            size += size_of_uleb128 (AT_index (a));
           else
             size += DWARF_OFFSET_SIZE;
 	  break;
@@ -11867,12 +11900,9 @@  add_AT_pubnames (dw_die_ref die)
 static void
 add_top_level_skeleton_die_attrs (dw_die_ref die)
 {
-  /* The splitter will fill in the file name.  It would be good to allocate
-     a fairly large string here to make it easy for the splitter though.  */
   const char *dwo_file_name = concat (aux_base_name, ".dwo", NULL);
   dw_attr_ref attr;
 
-  add_AT_lineptr (die, DW_AT_stmt_list, debug_line_section_label);
   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
@@ -11882,17 +11912,31 @@  add_top_level_skeleton_die_attrs (dw_die
   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;
-  /* The post compile splitter will fill in this value.  */
+
   add_AT_pubnames (die);
   add_AT_lineptr (die, DW_AT_GNU_ref_base, debug_ref_section_label);
   add_AT_lineptr (die, DW_AT_GNU_addr_base, debug_addr_section_label);
 }
 
-/* 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.  */
+/* Return the single type-unit die for skeleton type units.  */
 
-static dw_die_ref skeleton_type_unit = NULL;
+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.  */
 
@@ -11901,21 +11945,19 @@  unsigned char dwo_id_placeholder[8] = { 
 /* Output skeleton debug sections that point to the dwo file.  */
 
 static void
-output_skeleton_debug_sections (void)
+output_skeleton_debug_sections (dw_die_ref comp_unit)
 {
-  dw_die_ref comp_unit = gen_compile_unit_die (NULL);
-
   /* 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);
-  /* Only the compilation unit gets the dwo_id.  */
+
+  /* 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_GENERATE_INTERNAL_LABEL (debug_skeleton_info_section_label,
-                               DEBUG_SKELETON_INFO_SECTION_LABEL, 0);
   ASM_OUTPUT_LABEL (asm_out_file, debug_skeleton_info_section_label);
 
   /* Produce the skeleton compilation-unit header.  This one differs enough from
@@ -11932,8 +11974,6 @@  output_skeleton_debug_sections (void)
                        + size_of_die (comp_unit) + 1,
 		       "Length of Compilation Unit Info");
   dw2_asm_output_data (2, dwarf_version, "DWARF version number");
-  ASM_GENERATE_INTERNAL_LABEL (debug_skeleton_abbrev_section_label,
-                               DEBUG_SKELETON_ABBREV_SECTION_LABEL, 0);
   dw2_asm_output_offset (DWARF_OFFSET_SIZE, debug_skeleton_abbrev_section_label,
 			 debug_abbrev_section,
 			 "Offset Into Abbrev. Section");
@@ -11950,14 +11990,7 @@  output_skeleton_debug_sections (void)
 
   output_die_abbrevs (SKELETON_COMP_DIE_ABBREV, comp_unit);
   if (dwarf_version >= 4)
-    {
-      /* Because all skeleton type_units have identical dies, just generate
-         one, and output it repeatedly.  */
-      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;
-      output_die_abbrevs (SKELETON_TYPE_DIE_ABBREV, skeleton_type_unit);
-    }
+    output_die_abbrevs (SKELETON_TYPE_DIE_ABBREV, get_skeleton_type_unit ());
 
   dw2_asm_output_data (1, 0, "end of skeleton .debug_abbrev");
 }
@@ -12020,7 +12053,6 @@  output_comdat_type_unit (comdat_type_nod
     {
       /* Produce the skeleton type-unit header.  */
       const char *secname = ".debug_types";
-      gcc_assert (skeleton_type_unit);
 
       targetm.asm_out.named_section (secname,
                                      SECTION_DEBUG | SECTION_LINKONCE,
@@ -12033,7 +12065,7 @@  output_comdat_type_unit (comdat_type_nod
       dw2_asm_output_data (DWARF_OFFSET_SIZE,
                            DWARF_COMPILE_UNIT_HEADER_SIZE
                            - DWARF_INITIAL_LENGTH_SIZE
-                           + size_of_die (skeleton_type_unit)
+                           + 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");
@@ -12045,7 +12077,7 @@  output_comdat_type_unit (comdat_type_nod
       output_signature (node->signature, "Type Signature");
       dw2_asm_output_data (DWARF_OFFSET_SIZE, 0, "Offset to Type DIE");
 
-      output_die (skeleton_type_unit);
+      output_die (get_skeleton_type_unit ());
       /* dw2_asm_output_data (1, 0, "end of skeleton .debug_types"); */
     }
 }
@@ -14477,9 +14509,7 @@  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;
 
@@ -15341,9 +15371,7 @@  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);
 	}
@@ -16084,9 +16112,15 @@  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;
+          if (dwarf_split_debug_info && first_op == DW_OP_addr)
+            ret = new_addr_loc_descr (rtl, dtprel);
+          else
+            {
+              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);
@@ -16134,11 +16168,7 @@  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;
@@ -17072,9 +17102,7 @@  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);
@@ -20211,7 +20239,7 @@  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
@@ -22956,6 +22984,8 @@  dwarf2out_init (const char *filename ATT
                                                  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.  */
@@ -22965,6 +22995,8 @@  dwarf2out_init (const char *filename ATT
                                    DEBUG_SKELETON_LINE_SECTION_LABEL, 0);
       debug_str_offsets_section = get_section (DEBUG_STR_OFFSETS_SECTION,
                                                SECTION_DEBUG, NULL);
+      ASM_GENERATE_INTERNAL_LABEL (debug_skeleton_info_section_label,
+                                   DEBUG_SKELETON_INFO_SECTION_LABEL, 0);
     }
   debug_aranges_section = get_section (DEBUG_ARANGES_SECTION,
 				       SECTION_DEBUG, NULL);
@@ -23042,7 +23074,7 @@  output_indirect_string (void **h, void *
 {
   struct indirect_string_node *node = (struct indirect_string_node *) *h;
 
-  if (node->label && node->refcount)
+  if (node->form == DW_FORM_strp)
     {
       switch_to_section (debug_str_section);
       ASM_OUTPUT_LABEL (asm_out_file, node->label);
@@ -23124,6 +23156,12 @@  output_addr_table (void)
             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,
+                                                 AT_addr (node));
+            break;
           case dw_val_class_lbl_id:
             dw2_asm_output_addr (DWARF2_ADDR_SIZE, AT_lbl (node), "%s", name);
             break;
@@ -23629,23 +23667,32 @@  static bool
 resolve_addr_in_expr (dw_loc_descr_ref loc)
 {
   for (; loc; loc = loc->dw_loc_next)
-    if (((loc->dw_loc_opc == DW_OP_addr || loc->dtprel)
-	 && resolve_one_addr (&loc->dw_loc_oprnd1.v.val_addr, NULL))
-	|| (loc->dw_loc_opc == DW_OP_implicit_value
-	    && loc->dw_loc_oprnd2.val_class == dw_val_class_addr
-	    && resolve_one_addr (&loc->dw_loc_oprnd2.v.val_addr, NULL)))
-      return false;
-    else if (loc->dw_loc_opc == DW_OP_GNU_implicit_pointer
-	     && loc->dw_loc_oprnd1.val_class == dw_val_class_decl_ref)
-      {
-	dw_die_ref ref
-	  = lookup_decl_die (loc->dw_loc_oprnd1.v.val_decl_ref);
-	if (ref == NULL)
-	  return false;
-	loc->dw_loc_oprnd1.val_class = dw_val_class_die_ref;
-	loc->dw_loc_oprnd1.v.val_die_ref.die = ref;
-	loc->dw_loc_oprnd1.v.val_die_ref.external = 0;
-      }
+    {
+      if (loc->dw_loc_opc == DW_OP_GNU_addr_index)
+	{
+          unsigned int idx = loc->dw_loc_oprnd1.v.val_unsigned;
+          dw_attr_node *node = VEC_index (dw_attr_node, addr_index_table, idx);
+          if (resolve_one_addr (&node->dw_attr_val.v.val_addr, NULL))
+            return false;
+	}
+      else if (((loc->dw_loc_opc == DW_OP_addr || loc->dtprel)
+		&& resolve_one_addr (&loc->dw_loc_oprnd1.v.val_addr, NULL))
+	       || (loc->dw_loc_opc == DW_OP_implicit_value
+		   && loc->dw_loc_oprnd2.val_class == dw_val_class_addr
+		   && resolve_one_addr (&loc->dw_loc_oprnd2.v.val_addr, NULL)))
+	return false;
+      else if (loc->dw_loc_opc == DW_OP_GNU_implicit_pointer
+	       && loc->dw_loc_oprnd1.val_class == dw_val_class_decl_ref)
+	{
+	  dw_die_ref ref
+	    = lookup_decl_die (loc->dw_loc_oprnd1.v.val_decl_ref);
+	  if (ref == NULL)
+	    return false;
+	  loc->dw_loc_oprnd1.val_class = dw_val_class_die_ref;
+	  loc->dw_loc_oprnd1.v.val_die_ref.die = ref;
+	  loc->dw_loc_oprnd1.v.val_die_ref.external = 0;
+	}
+    }
   return true;
 }
 
@@ -23856,6 +23903,18 @@  hash_loc_operands (dw_loc_descr_ref loc,
 	}
       hash = iterative_hash_rtx (val1->v.val_addr, hash);
       break;
+    case DW_OP_GNU_addr_index:
+      {
+        dw_attr_ref attr = VEC_index (dw_attr_node, addr_index_table,
+                                      val1->v.val_unsigned);
+        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;
@@ -24011,6 +24070,17 @@  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:
+      {
+        dw_attr_node *attrx1 = VEC_index (dw_attr_node,
+                                          addr_index_table,
+                                          valx1->v.val_unsigned);
+        dw_attr_node *attry1 = VEC_index (dw_attr_node,
+                                          addr_index_table,
+                                          valy1->v.val_unsigned);
+        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
@@ -24133,6 +24203,15 @@  dwarf2out_finish (const char *filename)
   comdat_type_node *ctnode;
   htab_t comdat_type_table;
   unsigned int i;
+  dw_die_ref main_comp_unit_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 ();
 
   gen_scheduled_generic_parms_dies ();
   gen_remaining_tmpl_value_param_die_attribute ();
@@ -24305,10 +24384,10 @@  dwarf2out_finish (const char *filename)
       add_AT_addr (comp_unit_die (), DW_AT_entry_pc, const0_rtx);
 
       if (text_section_used)
-	add_ranges_by_labels (comp_unit_die (), text_section_label,
+	add_ranges_by_labels (main_comp_unit_die, text_section_label,
 			      text_end_label, &range_list_added);
       if (cold_text_section_used)
-	add_ranges_by_labels (comp_unit_die (), cold_text_section_label,
+	add_ranges_by_labels (main_comp_unit_die, cold_text_section_label,
 			      cold_end_label, &range_list_added);
 
       for (fde_idx = 0; fde_idx < fde_table_in_use; fde_idx++)
@@ -24316,10 +24395,10 @@  dwarf2out_finish (const char *filename)
 	  dw_fde_ref fde = &fde_table[fde_idx];
 
 	  if (!fde->in_std_section)
-	    add_ranges_by_labels (comp_unit_die (), fde->dw_fde_begin,
+	    add_ranges_by_labels (main_comp_unit_die, fde->dw_fde_begin,
 				  fde->dw_fde_end, &range_list_added);
 	  if (fde->dw_fde_second_begin && !fde->second_in_std_section)
-	    add_ranges_by_labels (comp_unit_die (), fde->dw_fde_second_begin,
+	    add_ranges_by_labels (main_comp_unit_die, fde->dw_fde_second_begin,
 				  fde->dw_fde_second_end, &range_list_added);
 	}
 
@@ -24328,11 +24407,11 @@  dwarf2out_finish (const char *filename)
     }
 
   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 (debug_info_level >= DINFO_LEVEL_VERBOSE)
-    add_AT_macptr (comp_unit_die (), DW_AT_macro_info, macinfo_section_label);
+    add_AT_macptr (main_comp_unit_die, DW_AT_macro_info, macinfo_section_label);
 
   if (have_location_lists)
     {
@@ -24340,15 +24419,6 @@  dwarf2out_finish (const char *filename)
       index_location_lists (comp_unit_die ());
     }
 
-  if (dwarf_split_debug_info)
-    {
-      /* Add a place-holder for the dwo_id to the comp-unit die.  Similarly, the
-         skeleton die gets a placeholder inside
-         output_skeleton_debug_sections.  */
-      add_AT_data8 (comp_unit_die (), DW_AT_GNU_dwo_id, dwo_id_placeholder);
-      output_skeleton_debug_sections ();
-    }
-
   /* Output all of the compilation units.  We put the main one last so that
      the offsets are available to output_pubnames.  */
   for (node = limbo_die_list; node; node = node->next)
@@ -24380,10 +24450,17 @@  dwarf2out_finish (const char *filename)
   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);
+
   /* Output the main compilation unit if non-empty or if .debug_macinfo
      will be emitted.  */
   output_comp_unit (comp_unit_die (), debug_info_level >= DINFO_LEVEL_VERBOSE);
 
+  if (dwarf_split_debug_info && info_section_emitted)
+    output_skeleton_debug_sections (main_comp_unit_die);
+
   /* Output the abbreviation table.  */
   switch_to_section (debug_abbrev_section);
   ASM_OUTPUT_LABEL (asm_out_file, abbrev_section_label);
@@ -24465,7 +24542,7 @@  dwarf2out_finish (const char *filename)
       dw2_asm_output_data (1, 0, "End compilation unit");
     }
 
-  if (dwarf_split_debug_info)
+  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);