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[PATCH] Fix PR53471, remove DECL_ASSEMBLER_NAME deferred compute


This removes defering DECL_ASSEMBLER_NAME computation inside dwarf2out.c,
something which is not possible when LTO is enabled during compilation
as we free up tree fields after we think the frontend is finished - but
DECL_ASSEMBLER_NAME computation involves a langhook and frontend specific
data.  In theory we try hard to properly assign assembler names for
everything reachable in free_lang_data, but the frontend hands even
"unreachable" types to dwarf2out via rest_of_type_compilation
and debug_hooks->type_decl.

Another approach would be to only call add_linkage_attr if the
assembler name was set meanwhile by other means, thus

Index: gcc/dwarf2out.c
===================================================================
--- gcc/dwarf2out.c     (revision 188063)
+++ gcc/dwarf2out.c     (working copy)
@@ -22158,7 +22158,8 @@ dwarf2out_finish (const char *filename)
   for (node = deferred_asm_name; node; node = node->next)
     {
       tree decl = node->created_for;
-      if (DECL_ASSEMBLER_NAME (decl) != DECL_NAME (decl))
+      if (DECL_ASSEMBLER_NAME_SET_P (decl)
+         && DECL_ASSEMBLER_NAME (decl) != DECL_NAME (decl))
        {
          add_linkage_attr (node->die, decl);
          move_linkage_attr (node->die);

But I bootstrapped and tested the following variant instead
which generates the same code and debuginfo with -O0 -g for
tramp3d at the cost of a 0.01% compile-time hit (not sure,
but I suppose the deferral was for a reason?).

Ok?

Thanks,
Richard.

2012-05-31  Richard Guenther  <rguenther@suse.de>

	PR debug/53471
	* dwarf2out.c (deferred_asm_name): Remove.
	(add_linkage_name): Force DECL_ASSEMBLER_NAME creation here.
	(move_linkage_attr): Remove.
	(dwarf2out_finish): Do not process deferred_asm_name.

Index: gcc/dwarf2out.c
===================================================================
--- gcc/dwarf2out.c	(revision 188056)
+++ gcc/dwarf2out.c	(working copy)
@@ -2652,10 +2652,6 @@ static GTY(()) comdat_type_node *comdat_
 /* A list of DIEs with a NULL parent waiting to be relocated.  */
 static GTY(()) limbo_die_node *limbo_die_list;
 
-/* A list of DIEs for which we may have to generate
-   DW_AT_{,MIPS_}linkage_name once their DECL_ASSEMBLER_NAMEs are set.  */
-static GTY(()) limbo_die_node *deferred_asm_name;
-
 /* Filenames referenced by this compilation unit.  */
 static GTY((param_is (struct dwarf_file_data))) htab_t file_table;
 
@@ -15394,22 +15390,9 @@ add_linkage_name (dw_die_ref die, tree d
        && TREE_PUBLIC (decl)
        && !DECL_ABSTRACT (decl)
        && !(TREE_CODE (decl) == VAR_DECL && DECL_REGISTER (decl))
-       && die->die_tag != DW_TAG_member)
-    {
-      /* Defer until we have an assembler name set.  */
-      if (!DECL_ASSEMBLER_NAME_SET_P (decl))
-	{
-	  limbo_die_node *asm_name;
-
-	  asm_name = ggc_alloc_cleared_limbo_die_node ();
-	  asm_name->die = die;
-	  asm_name->created_for = decl;
-	  asm_name->next = deferred_asm_name;
-	  deferred_asm_name = asm_name;
-	}
-      else if (DECL_ASSEMBLER_NAME (decl) != DECL_NAME (decl))
-	add_linkage_attr (die, decl);
-    }
+       && die->die_tag != DW_TAG_member
+       && DECL_ASSEMBLER_NAME (decl) != DECL_NAME (decl))
+    add_linkage_attr (die, decl);
 }
 
 /* Add a DW_AT_name attribute and source coordinate attribute for the
@@ -21161,37 +21144,6 @@ htab_ct_eq (const void *of1, const void
                     DWARF_TYPE_SIGNATURE_SIZE));
 }
 
-/* Move a DW_AT_{,MIPS_}linkage_name attribute just added to dw_die_ref
-   to the location it would have been added, should we know its
-   DECL_ASSEMBLER_NAME when we added other attributes.  This will
-   probably improve compactness of debug info, removing equivalent
-   abbrevs, and hide any differences caused by deferring the
-   computation of the assembler name, triggered by e.g. PCH.  */
-
-static inline void
-move_linkage_attr (dw_die_ref die)
-{
-  unsigned ix = VEC_length (dw_attr_node, die->die_attr);
-  dw_attr_node linkage = *VEC_index (dw_attr_node, die->die_attr, ix - 1);
-
-  gcc_assert (linkage.dw_attr == DW_AT_linkage_name
-	      || linkage.dw_attr == DW_AT_MIPS_linkage_name);
-
-  while (--ix > 0)
-    {
-      dw_attr_node *prev = VEC_index (dw_attr_node, die->die_attr, ix - 1);
-
-      if (prev->dw_attr == DW_AT_decl_line || prev->dw_attr == DW_AT_name)
-	break;
-    }
-
-  if (ix != VEC_length (dw_attr_node, die->die_attr) - 1)
-    {
-      VEC_pop (dw_attr_node, die->die_attr);
-      VEC_quick_insert (dw_attr_node, die->die_attr, ix, &linkage);
-    }
-}
-
 /* Helper function for resolve_addr, mark DW_TAG_base_type nodes
    referenced from typed stack ops and count how often they are used.  */
 
@@ -22155,18 +22107,6 @@ dwarf2out_finish (const char *filename)
   resolve_addr (comp_unit_die ());
   move_marked_base_types ();
 
-  for (node = deferred_asm_name; node; node = node->next)
-    {
-      tree decl = node->created_for;
-      if (DECL_ASSEMBLER_NAME (decl) != DECL_NAME (decl))
-	{
-	  add_linkage_attr (node->die, decl);
-	  move_linkage_attr (node->die);
-	}
-    }
-
-  deferred_asm_name = NULL;
-
   /* Walk through the list of incomplete types again, trying once more to
      emit full debugging info for them.  */
   retry_incomplete_types ();


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