gdb/
2014-10-01  Jan Kratochvil  <jan.kratochvil@redhat.com>

	Fix 100x slowdown regression on DWZ files.
	* dwarf2read.c (struct dwarf2_per_objfile): Add lineinfo_hash.
	(struct dwarf2_lineinfo, dwarf2_lineinfo_hash, dwarf2_lineinfo_eq): New.
	(struct dwarf2_cu): Add lineinfo.
	(handle_DW_AT_stmt_list): Use dwarf2_per_objfile->lineinfo_hash, set
	cu->lineinfo.
	(new_symbol_full): Use cu->lineinfo.

diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c
index 9d0ee13..b24c133 100644
--- a/gdb/dwarf2read.c
+++ b/gdb/dwarf2read.c
@@ -309,8 +309,51 @@ struct dwarf2_per_objfile
 
   /* The CUs we recently read.  */
   VEC (dwarf2_per_cu_ptr) *just_read_cus;
+
+  /* Table containing struct dwarf2_lineinfo.  */
+  htab_t lineinfo_hash;
+};
+
+/* Table mapping .debug_line offsets to any symtab where they are
+   instantiated.  */
+
+struct dwarf2_lineinfo
+{
+  /* Offset of line number information in .debug_line section.  */
+  sect_offset offset;
+  unsigned offset_in_dwz : 1;
+
+  /* Number of entries in file_to_symtab array.  */
+  unsigned file_to_symtab_count;
+
+  /* struct is sized to contain FILE_TO_SYMTAB_COUNT elements of this array.
+     Map each DW_AT_decl_file entry to any instantiation of matching symtab.
+     This array is numbered from zero, DW_AT_decl_file is numbered from one.  */
+  struct symtab *file_to_symtab[1];
 };
 
+/* Hash function for a dwarf2_lineinfo.  */
+
+static hashval_t
+dwarf2_lineinfo_hash (const void *item)
+{
+  const struct dwarf2_lineinfo *ofs = item;
+
+  return ofs->offset.sect_off ^ ofs->offset_in_dwz;
+}
+
+/* Equality function for a dwarf2_lineinfo.  */
+
+static int
+dwarf2_lineinfo_eq (const void *item_lhs, const void *item_rhs)
+{
+  const struct dwarf2_lineinfo *ofs_lhs = item_lhs;
+  const struct dwarf2_lineinfo *ofs_rhs = item_rhs;
+
+  return (ofs_lhs->offset.sect_off == ofs_rhs->offset.sect_off
+	  && ofs_lhs->offset_in_dwz == ofs_rhs->offset_in_dwz);
+}
+
 static struct dwarf2_per_objfile *dwarf2_per_objfile;
 
 /* Default names of the debugging sections.  */
@@ -489,6 +532,10 @@ struct dwarf2_cu
   /* Header data from the line table, during full symbol processing.  */
   struct line_header *line_header;
 
+  /* Table mapping .debug_line offsets to any symtab where they are
+     instantiated.  It contains subset of LINE_HEADER information.  */
+  struct dwarf2_lineinfo *lineinfo;
+
   /* A list of methods which need to have physnames computed
      after all type information has been read.  */
   VEC (delayed_method_info) *method_list;
@@ -8975,24 +9022,61 @@ static void
 handle_DW_AT_stmt_list (struct die_info *die, struct dwarf2_cu *cu,
 			const char *comp_dir, CORE_ADDR lowpc) /* ARI: editCase function */
 {
+  struct objfile *objfile = dwarf2_per_objfile->objfile;
   struct attribute *attr;
+  unsigned int line_offset;
+  struct dwarf2_lineinfo lineinfo;
+  struct line_header *line_header;
+  unsigned u;
+  void **slot;
 
   gdb_assert (! cu->per_cu->is_debug_types);
 
   attr = dwarf2_attr (die, DW_AT_stmt_list, cu);
-  if (attr)
+  if (attr == NULL)
+    return;
+
+  line_offset = DW_UNSND (attr);
+
+  if (dwarf2_per_objfile->lineinfo_hash == NULL)
     {
-      unsigned int line_offset = DW_UNSND (attr);
-      struct line_header *line_header
-	= dwarf_decode_line_header (line_offset, cu);
+      dwarf2_per_objfile->lineinfo_hash =
+	htab_create_alloc_ex (127, dwarf2_lineinfo_hash, dwarf2_lineinfo_eq,
+			      NULL, &objfile->objfile_obstack,
+			      hashtab_obstack_allocate,
+			      dummy_obstack_deallocate);
+    }
 
-      if (line_header)
-	{
-	  cu->line_header = line_header;
-	  make_cleanup (free_cu_line_header, cu);
-	  dwarf_decode_lines (line_header, comp_dir, cu, NULL, lowpc);
-	}
+  lineinfo.offset.sect_off = line_offset;
+  lineinfo.offset_in_dwz = cu->per_cu->is_dwz;
+  slot = htab_find_slot (dwarf2_per_objfile->lineinfo_hash, &lineinfo, INSERT);
+
+  /* For DW_TAG_compile_unit we need info like symtab::linetable which
+     is not present in *SLOT.  */
+  if (die->tag == DW_TAG_partial_unit && *slot != NULL)
+    {
+      cu->lineinfo = *slot;
+      return;
     }
+
+  line_header = dwarf_decode_line_header (line_offset, cu);
+  if (line_header == NULL)
+    return;
+  cu->line_header = line_header;
+  make_cleanup (free_cu_line_header, cu);
+  dwarf_decode_lines (line_header, comp_dir, cu, NULL, lowpc);
+
+  cu->lineinfo = obstack_alloc (&objfile->objfile_obstack,
+				(sizeof (*cu->lineinfo)
+				 + (sizeof (*cu->lineinfo->file_to_symtab)
+				    * (line_header->num_file_names - 1))));
+  cu->lineinfo->offset.sect_off = line_offset;
+  cu->lineinfo->offset_in_dwz = cu->per_cu->is_dwz;
+  cu->lineinfo->file_to_symtab_count = line_header->num_file_names;
+  for (u = 0; u < cu->lineinfo->file_to_symtab_count; u++)
+    cu->lineinfo->file_to_symtab[u] = line_header->file_names[u].symtab;
+  if (*slot == NULL)
+    *slot = cu->lineinfo;
 }
 
 /* Process DW_TAG_compile_unit or DW_TAG_partial_unit.  */
@@ -17870,17 +17954,12 @@ new_symbol_full (struct die_info *die, struct type *type, struct dwarf2_cu *cu,
 	{
 	  int file_index = DW_UNSND (attr);
 
-	  if (cu->line_header == NULL
-	      || file_index > cu->line_header->num_file_names)
+	  if (cu->lineinfo == NULL
+	      || file_index > cu->lineinfo->file_to_symtab_count)
 	    complaint (&symfile_complaints,
 		       _("file index out of range"));
 	  else if (file_index > 0)
-	    {
-	      struct file_entry *fe;
-
-	      fe = &cu->line_header->file_names[file_index - 1];
-	      SYMBOL_SYMTAB (sym) = fe->symtab;
-	    }
+	    SYMBOL_SYMTAB (sym) = cu->lineinfo->file_to_symtab[file_index - 1];
 	}
 
       switch (die->tag)