Re: dynsym/dynstr sort speedup - patch ...

[michael meeks <michael dot meeks at novell dot com>]

Apologies; patch attached.
-- 
 michael.meeks@novell.com  <><, Pseudo Engineer, itinerant idiot

diff -u -r -x texis -x Makeconfig -x version.h -x '*.o' -x '*.1' -x 'Makefile*' -x 'config*' -x libtool -x '*.info' -x '*.tex' binutils-2.16.91.0.4/bfd/elf-bfd.h binutils.current/bfd/elf-bfd.h
--- binutils-2.16.91.0.4/bfd/elf-bfd.h	2005-12-22 10:42:52.000000000 +0000
+++ binutils.current/bfd/elf-bfd.h	2005-12-22 10:42:56.000000000 +0000
@@ -340,6 +340,10 @@
 {
   struct bfd_link_hash_table root;
 
+  /* Symbol sort order for final traversal at output */
+  unsigned int sorted_size;
+  struct elf_link_hash_entry **sorted;
+
   /* Whether we have created the special dynamic sections required
      when linking against or generating a shared object.  */
   bfd_boolean dynamic_sections_created;
@@ -418,11 +422,16 @@
 /* Traverse an ELF linker hash table.  */
 
 #define elf_link_hash_traverse(table, func, info)			\
-  (bfd_link_hash_traverse						\
-   (&(table)->root,							\
-    (bfd_boolean (*) (struct bfd_link_hash_entry *, void *)) (func),	\
+  (_bfd_elf_link_hash_traverse						\
+   ((table),								\
+    (bfd_boolean (*) (struct elf_link_hash_entry *, void *)) (func),	\
     (info)))
 
+void _bfd_elf_link_hash_traverse
+  (struct elf_link_hash_table *table,
+   bfd_boolean (*func) (struct elf_link_hash_entry *, void *),
+   void *info);
+
 /* Get the ELF linker hash table from a link_info structure.  */
 
 #define elf_hash_table(p) ((struct elf_link_hash_table *) ((p)->hash))
@@ -1593,7 +1602,7 @@
 extern bfd_boolean _bfd_elf_strtab_emit
   (bfd *, struct elf_strtab_hash *);
 extern void _bfd_elf_strtab_finalize
-  (struct elf_strtab_hash *);
+  (struct elf_strtab_hash *, size_t);
 
 extern bfd_boolean _bfd_elf_discard_section_eh_frame
   (bfd *, struct bfd_link_info *, asection *,
diff -u -r -x texis -x Makeconfig -x version.h -x '*.o' -x '*.1' -x 'Makefile*' -x 'config*' -x libtool -x '*.info' -x '*.tex' binutils-2.16.91.0.4/bfd/elf.c binutils.current/bfd/elf.c
--- binutils-2.16.91.0.4/bfd/elf.c	2005-12-22 10:42:52.000000000 +0000
+++ binutils.current/bfd/elf.c	2005-12-22 10:42:56.000000000 +0000
@@ -1560,6 +1560,8 @@
   table->tls_size = 0;
   table->loaded = NULL;
   table->is_relocatable_executable = FALSE;
+  table->sorted = NULL;
+  table->sorted_size = 0;
 
   ret = _bfd_link_hash_table_init (&table->root, abfd, newfunc);
   table->root.type = bfd_link_elf_hash_table;
@@ -2983,7 +2985,7 @@
       _bfd_elf_strtab_addref (elf_shstrtab (abfd), t->strtab_hdr.sh_name);
     }
 
-  _bfd_elf_strtab_finalize (elf_shstrtab (abfd));
+  _bfd_elf_strtab_finalize (elf_shstrtab (abfd), 0);
   t->shstrtab_hdr.sh_size = _bfd_elf_strtab_size (elf_shstrtab (abfd));
 
   elf_numsections (abfd) = section_number;
diff -u -r -x texis -x Makeconfig -x version.h -x '*.o' -x '*.1' -x 'Makefile*' -x 'config*' -x libtool -x '*.info' -x '*.tex' binutils-2.16.91.0.4/bfd/elflink.c binutils.current/bfd/elflink.c
--- binutils-2.16.91.0.4/bfd/elflink.c	2005-12-22 10:42:52.000000000 +0000
+++ binutils.current/bfd/elflink.c	2005-12-22 10:42:56.000000000 +0000
@@ -3007,7 +3007,8 @@
   const struct elf_backend_data *bed;
   bfd_byte *extdyn;
 
-  _bfd_elf_strtab_finalize (dynstr);
+  _bfd_elf_strtab_finalize (dynstr,
+			    elf_hash_table (info)->bucketcount);
   size = _bfd_elf_strtab_size (dynstr);
 
   bed = get_elf_backend_data (dynobj);
@@ -4920,6 +4922,125 @@
   return best_size;
 }
 
+void _bfd_elf_link_hash_traverse
+  (struct elf_link_hash_table *table,
+   bfd_boolean (*func) (struct elf_link_hash_entry *, void *),
+   void *info)
+{
+  if (!table->sorted)
+    bfd_link_hash_traverse						\
+      (&(table)->root,							\
+       (bfd_boolean (*) (struct bfd_link_hash_entry *, void *)) (func),	\
+       (info));
+  else
+    {
+      unsigned int i;
+      for (i = 0; i < table->sorted_size; i++)
+        {
+          if (! func (table->sorted[i], info))
+	    return;
+	}
+    }
+}
+
+/* Where is the qsort closure ? */
+static size_t give_me_a_bucket_count = 0;
+
+/* Sort by elf hash value % buckets  */
+static int
+elf_sort_dynsym_hash (const void *arg1, const void *arg2)
+{
+  size_t h1_bucket, h2_bucket;
+  const struct elf_link_hash_entry *h1;
+  const struct elf_link_hash_entry *h2;
+
+  h1 = *(const struct elf_link_hash_entry **) arg1;
+  h2 = *(const struct elf_link_hash_entry **) arg2;
+
+  h1_bucket = h1->u.elf_hash_value % give_me_a_bucket_count;
+  h2_bucket = h2->u.elf_hash_value % give_me_a_bucket_count;
+
+  if (h1_bucket > h2_bucket)
+    return 1;
+  if (h1_bucket < h2_bucket)
+    return -1;
+
+  return 0;
+}
+
+struct elf_dynsym_sort_info
+{
+  bfd_boolean  do_dynsym;
+  unsigned int alloc_size;
+  unsigned int sorted_size;
+  struct elf_link_hash_entry **sorted_syms;
+};
+
+/* collect sym entries into an array for later sorting */
+static bfd_boolean
+elf_sort_collect_dynsyms (struct elf_link_hash_entry *h, void *data)
+{
+  struct elf_dynsym_sort_info *sinfo = data;
+
+  if ((sinfo->do_dynsym && h->dynindx < 0) ||
+      (!sinfo->do_dynsym && h->dynindx >= 0))
+    return TRUE;
+
+  if (sinfo->sorted_size >= sinfo->alloc_size)
+    {
+      sinfo->alloc_size *= 2;
+      /* FIXME: need to free this data too ... */
+      sinfo->sorted_syms = bfd_realloc (sinfo->sorted_syms,
+					 sizeof (struct elf_link_hash_entry *) *
+					 sinfo->alloc_size);
+    }
+  sinfo->sorted_syms [sinfo->sorted_size++] = h;
+
+  return TRUE;
+}
+
+/*
+ * Sort the exported elf symbols by elf_hash % bucketcount to
+ * improve run-time linker cache behavior. Subsequent
+ * elf_link_hash_traverse calls will reflect this new order.
+ */
+static bfd_boolean
+_bfd_elf_sort_dynsyms (struct bfd_link_info *info)
+{
+  struct elf_dynsym_sort_info sinfo;
+
+  sinfo.alloc_size = 8;
+  sinfo.sorted_syms = bfd_malloc (sizeof (struct elf_link_hash_entry *) *
+				  sinfo.alloc_size);
+  if (!sinfo.sorted_syms)
+    return FALSE;
+
+  sinfo.sorted_size = 0;
+
+  /* append dynsyms for sorting */
+  sinfo.do_dynsym = TRUE;
+  elf_link_hash_traverse (elf_hash_table (info), elf_sort_collect_dynsyms, &sinfo);
+
+  /* sort them ... */
+  if (getenv ("DO_SORT_SYMS")) {
+	  fprintf (stderr, "Sorting dynsym\n");
+	  give_me_a_bucket_count = elf_hash_table (info)->bucketcount;
+	  qsort (sinfo.sorted_syms, sinfo.sorted_size,
+		 sizeof (struct elf_link_hash_entry *),
+		 elf_sort_dynsym_hash);
+  }
+
+  /* append everything else */
+  sinfo.do_dynsym = FALSE;
+  elf_link_hash_traverse (elf_hash_table (info), elf_sort_collect_dynsyms, &sinfo);
+
+  /* transfer to the elf hash: FIXME - leaks ... */
+  elf_hash_table (info)->sorted = sinfo.sorted_syms;
+  elf_hash_table (info)->sorted_size = sinfo.sorted_size;
+
+  return TRUE;
+}
+
 /* Set up the sizes and contents of the ELF dynamic sections.  This is
    called by the ELF linker emulation before_allocation routine.  We
    must set the sizes of the sections before the linker sets the
@@ -5686,6 +5807,7 @@
 	 section symbol for each output section, which come first.
 	 Next come all of the back-end allocated local dynamic syms,
 	 followed by the rest of the global symbols.  */
+      /* To sort these optimally we need the correct bucketcount */
 
       dynsymcount = _bfd_elf_link_renumber_dynsyms (output_bfd, info,
 						    &section_sym_count);
@@ -5756,6 +5878,15 @@
       for (dtagcount = 0; dtagcount <= info->spare_dynamic_tags; ++dtagcount)
 	if (!_bfd_elf_add_dynamic_entry (info, DT_NULL, 0))
 	  return FALSE;
+
+      /* Sort .dynsym to accelerate runtime linking */
+      { /* FIXME - make this conditional (?) */
+        if (!_bfd_elf_sort_dynsyms (info))
+          return FALSE;
+	/* reflect the new sorting order */
+	_bfd_elf_link_renumber_dynsyms (output_bfd, info,
+					&section_sym_count);
+      }
     }
 
   return TRUE;
diff -u -r -x texis -x Makeconfig -x version.h -x '*.o' -x '*.1' -x 'Makefile*' -x 'config*' -x libtool -x '*.info' -x '*.tex' binutils-2.16.91.0.4/bfd/elflink.c~ binutils.current/bfd/elflink.c~
--- binutils-2.16.91.0.4/bfd/elflink.c~	2005-12-07 11:20:22.000000000 +0000
+++ binutils.current/bfd/elflink.c~	2005-12-22 09:26:41.000000000 +0000
@@ -3022,7 +3022,8 @@
   const struct elf_backend_data *bed;
   bfd_byte *extdyn;
 
-  _bfd_elf_strtab_finalize (dynstr);
+  _bfd_elf_strtab_finalize (dynstr,
+			    elf_hash_table (info)->bucketcount);
   size = _bfd_elf_strtab_size (dynstr);
 
   bed = get_elf_backend_data (dynobj);
@@ -4983,6 +4986,133 @@
   return best_size;
 }
 
+void _bfd_elf_link_hash_traverse
+  (struct elf_link_hash_table *table,
+   bfd_boolean (*func) (struct elf_link_hash_entry *, void *),
+   void *info)
+{
+  if (!table->sorted)
+    bfd_link_hash_traverse						\
+      (&(table)->root,							\
+       (bfd_boolean (*) (struct bfd_link_hash_entry *, void *)) (func),	\
+       (info));
+  else
+    {
+      int i;
+      for (i = 0; i < table->sorted_size; i++)
+        {
+          if (! func (table->sorted[i], info))
+	    return;
+	}
+    }
+}
+
+/* Where is the qsort closure ? */
+static size_t give_me_a_bucket_count = 0;
+
+/* Sort by elf hash value % buckets  */
+static int
+elf_sort_dynsym_hash (const void *arg1, const void *arg2)
+{
+  size_t h1_bucket, h2_bucket;
+  const struct elf_link_hash_entry *h1;
+  const struct elf_link_hash_entry *h2;
+
+  h1 = *(const struct elf_link_hash_entry **) arg1;
+  h2 = *(const struct elf_link_hash_entry **) arg2;
+
+  h1_bucket = h1->u.elf_hash_value % give_me_a_bucket_count;
+  h2_bucket = h2->u.elf_hash_value % give_me_a_bucket_count;
+
+  /*  fprintf (stderr, "Sort: '%s'(0x%x) <> '%s'(0x%x) (%d)\n",
+	   h1->root.root.string, h1_bucket,
+	   h2->root.root.string, h2_bucket,
+	   give_me_a_bucket_count); */
+
+  /* Hack to test with objdump */
+  /*  return strcmp (h1->root.root.string, h2->root.root.string); */
+
+  if (h1_bucket > h2_bucket)
+    return 1;
+  if (h1_bucket < h2_bucket)
+    return -1;
+
+  return 0;
+}
+
+struct elf_dynsym_sort_info
+{
+  bfd_boolean  do_dynsym;
+  unsigned int alloc_size;
+  unsigned int sorted_size;
+  struct elf_link_hash_entry **sorted_syms;
+};
+
+/* collect sym entries into an array for later sorting */
+static bfd_boolean
+elf_sort_collect_dynsyms (struct elf_link_hash_entry *h, void *data)
+{
+  struct elf_dynsym_sort_info *sinfo = data;
+
+  if ((sinfo->do_dynsym && h->dynindx < 0) ||
+      (!sinfo->do_dynsym && h->dynindx >= 0))
+    return TRUE;
+
+  if (sinfo->sorted_size >= sinfo->alloc_size)
+    {
+      sinfo->alloc_size *= 2;
+      /* FIXME: need to free this data too ... */
+      sinfo->sorted_syms = bfd_realloc (sinfo->sorted_syms,
+					 sizeof (struct elf_link_hash_entry *) *
+					 sinfo->alloc_size);
+    }
+  sinfo->sorted_syms [sinfo->sorted_size++] = h;
+
+  return TRUE;
+}
+
+/*
+ * Sort the exported elf symbols by elf_hash % bucketcount to
+ * improve run-time linker cache behavior. Subsequent
+ * elf_link_hash_traverse calls will reflect this new order.
+ */
+static bfd_boolean
+_bfd_elf_sort_dynsyms (struct bfd_link_info *info)
+{
+  struct elf_dynsym_sort_info sinfo;
+
+  sinfo.alloc_size = 8;
+  sinfo.sorted_syms = bfd_malloc (sizeof (struct elf_link_hash_entry *) *
+				  sinfo.alloc_size);
+  if (!sinfo.sorted_syms)
+    return FALSE;
+
+  sinfo.sorted_size = 0;
+
+  /* append dynsyms for sorting */
+  sinfo.do_dynsym = TRUE;
+  elf_link_hash_traverse (elf_hash_table (info), elf_sort_collect_dynsyms, &sinfo);
+
+  /* sort them ... */
+  if (getenv ("DO_SORT_SYMS")) {
+	  fprintf (stderr, "sort dynsym\n");
+	  give_me_a_bucket_count = elf_hash_table (info)->bucketcount;
+	  qsort (sinfo.sorted_syms, sinfo.sorted_size,
+		 sizeof (struct elf_link_hash_entry *),
+		 elf_sort_dynsym_hash);
+  }
+
+  /* append everything else */
+  sinfo.do_dynsym = FALSE;
+  elf_link_hash_traverse (elf_hash_table (info), elf_sort_collect_dynsyms, &sinfo);
+
+  /* transfer to the elf hash: FIXME - leaks ... */
+  elf_hash_table (info)->sorted = sinfo.sorted_syms;
+  elf_hash_table (info)->sorted_size = sinfo.sorted_size;
+
+  return TRUE;
+}
+
 /* Set up the sizes and contents of the ELF dynamic sections.  This is
    called by the ELF linker emulation before_allocation routine.  We
    must set the sizes of the sections before the linker sets the
@@ -5749,6 +5880,7 @@
 	 section symbol for each output section, which come first.
 	 Next come all of the back-end allocated local dynamic syms,
 	 followed by the rest of the global symbols.  */
+      /* To sort these optimally we need the correct bucketcount */
 
       dynsymcount = _bfd_elf_link_renumber_dynsyms (output_bfd, info,
 						    &section_sym_count);
@@ -5837,6 +5969,16 @@
       for (dtagcount = 0; dtagcount <= info->spare_dynamic_tags; ++dtagcount)
 	if (!_bfd_elf_add_dynamic_entry (info, DT_NULL, 0))
 	  return FALSE;
+
+      
+      /* Sort the elf symbols to accelerate linking */
+      { /* HACK - FIXME - make this conditional (?) */
+        if (!_bfd_elf_sort_dynsyms (info))
+          return FALSE;
+	/* reflect the new sorting order */
+	_bfd_elf_link_renumber_dynsyms (output_bfd, info);
+      }
+
     }
 
   return TRUE;
diff -u -r -x texis -x Makeconfig -x version.h -x '*.o' -x '*.1' -x 'Makefile*' -x 'config*' -x libtool -x '*.info' -x '*.tex' binutils-2.16.91.0.4/bfd/elf-strtab.c binutils.current/bfd/elf-strtab.c
--- binutils-2.16.91.0.4/bfd/elf-strtab.c	2005-05-10 23:46:41.000000000 +0100
+++ binutils.current/bfd/elf-strtab.c	2005-12-22 10:40:32.000000000 +0000
@@ -39,6 +39,7 @@
     /* Entry this is a suffix of (if len < 0).  */
     struct elf_strtab_hash_entry *suffix;
   } u;
+  long elf_hash_value;
 };
 
 /* The strtab hash table.  */
@@ -54,6 +55,8 @@
   bfd_size_type sec_size;
   /* Array of pointers to strtab entries.  */
   struct elf_strtab_hash_entry **array;
+  /* Array of pointers to strtab entries.  */
+  struct elf_strtab_hash_entry **array_sorted;
 };
 
 /* Routine to create an entry in a section merge hashtab.  */
@@ -117,6 +120,7 @@
     }
 
   table->array[0] = NULL;
+  table->array_sorted = NULL;
 
   return table;
 }
@@ -128,6 +132,8 @@
 {
   bfd_hash_table_free (&tab->table);
   free (tab->array);
+  if (tab->array_sorted)
+    free (tab->array_sorted);
   free (tab);
 }
 
@@ -170,6 +176,12 @@
 
       entry->u.index = tab->size++;
       tab->array[entry->u.index] = entry;
+
+      {
+        if (strrchr (str, ELF_VER_CHR))
+	  fprintf (stderr, "FIXME: Invalid hash generated for '%s'\n", str);
+	entry->elf_hash_value = bfd_elf_hash (str);
+      }
     }
   return entry->u.index;
 }
@@ -229,6 +241,12 @@
 _bfd_elf_strtab_emit (register bfd *abfd, struct elf_strtab_hash *tab)
 {
   bfd_size_type off = 1, i;
+  struct elf_strtab_hash_entry **array;
+
+  if (tab->array_sorted != NULL)
+    array = tab->array_sorted;
+  else
+    array = tab->array;
 
   if (bfd_bwrite ("", 1, abfd) != 1)
     return FALSE;
@@ -238,18 +256,17 @@
       register const char *str;
       register unsigned int len;
 
-      BFD_ASSERT (tab->array[i]->refcount == 0);
-      len = tab->array[i]->len;
+      BFD_ASSERT (array[i]->refcount == 0);
+      len = array[i]->len;
       if ((int) len < 0)
 	continue;
 
-      str = tab->array[i]->root.string;
+      str = array[i]->root.string;
       if (bfd_bwrite (str, len, abfd) != len)
 	return FALSE;
 
       off += len;
     }
-
   BFD_ASSERT (off == tab->sec_size);
   return TRUE;
 }
@@ -278,6 +295,33 @@
   return lenA - lenB;
 }
 
+/* Where is the qsort closure ? */
+static size_t give_me_a_bucket_count = 0;
+
+/* Sort by elf hash value % buckets  */
+static int
+hash_compare (const void *a, const void *b)
+{
+  size_t h1_bucket, h2_bucket;
+  struct elf_strtab_hash_entry *A = *(struct elf_strtab_hash_entry **) a;
+  struct elf_strtab_hash_entry *B = *(struct elf_strtab_hash_entry **) b;
+
+  h1_bucket = A->elf_hash_value % give_me_a_bucket_count;
+  h2_bucket = B->elf_hash_value % give_me_a_bucket_count;
+
+  if (h1_bucket > h2_bucket)
+    return 1;
+  if (h1_bucket < h2_bucket)
+    return -1;
+
+  /* Make qsort faster for lots of identical empty symbols */
+  if (a > b)
+    return 1;
+  if (a < b)
+    return -1;
+  return 0;
+}
+
 static inline int
 is_suffix (const struct elf_strtab_hash_entry *A,
 	   const struct elf_strtab_hash_entry *B)
@@ -293,9 +337,8 @@
 
 /* This function assigns final string table offsets for used strings,
    merging strings matching suffixes of longer strings if possible.  */
-
 void
-_bfd_elf_strtab_finalize (struct elf_strtab_hash *tab)
+_bfd_elf_strtab_finalize (struct elf_strtab_hash *tab, size_t bucket_count)
 {
   struct elf_strtab_hash_entry **array, **a, *e;
   bfd_size_type size, amt;
@@ -361,15 +404,27 @@
 	}
     }
 
-alloc_failure:
-  if (array)
-    free (array);
+  if (bucket_count && !getenv ("DONTSORT_SYMS"))
+    {
+      fprintf (stderr, "Sorting symbols\n");
+      give_me_a_bucket_count = bucket_count;
+      for (i = 0; i < tab->size; ++i)
+        array[i] = tab->array[i];
+      qsort (array + 1, tab->size - 1, sizeof (struct elf_strtab_hash_entry *), hash_compare);
+      tab->array_sorted = array;
+    }
+  else
+    {
+      free (array);
+ alloc_failure:
+      array = tab->array;
+    }
 
   /* Assign positions to the strings we want to keep.  */
   size = 1;
   for (i = 1; i < tab->size; ++i)
     {
-      e = tab->array[i];
+      e = array[i];
       if (e->refcount && e->len > 0)
 	{
 	  e->u.index = size;
@@ -382,7 +437,7 @@
   /* Adjust the rest.  */
   for (i = 1; i < tab->size; ++i)
     {
-      e = tab->array[i];
+      e = array[i];
       if (e->refcount && e->len < 0)
 	e->u.index = e->u.suffix->u.index + (e->u.suffix->len + e->len);
     }