Home Original page

RFC: Speeding up libstdc++.so with --dynamic-list-data

H. J. Lu hjl@lucon.org
Tue Jan 9 02:26:00 GMT 2007 
I am enclosing a patch to implement a new linker swicth,
--dynamic-list-data. It is -Bsymbolic for function symbols only.
I tried it with C, C++, Java and Fortran on Linux/ia32, Linux/x86-64
and Linux/ia64. There are only a few regressions. The function calls
within the new resulting DSOs will bind locally. It speeds up
the enclosed C++ testcase by

1. 23% on ia64.
2. 6% on ia32.
3. 3% on x86-64.

Should we consider such optimization?


H.J.
-------------- next part --------------
bfd/

2007-01-05 H.J. Lu  <hongjiu.lu@intel.com>

	PR ld/3831
	* elf-bfd.h (bfd_elf_link_mark_dynamic_symbol): Add an
	argument, Elf_Internal_Sym *.

	* elflink.c (bfd_elf_link_mark_dynamic_symbol): Mark a data
	symbol dynamic if info->dynamic_data is TRUE.
	(bfd_elf_record_link_assignment): Updated call to
	bfd_elf_record_link_assignment.
	(_bfd_elf_merge_symbol): Likewise.  Always call
	bfd_elf_link_mark_dynamic_symbol.

include/

2007-01-05 H.J. Lu  <hongjiu.lu@intel.com>

	PR ld/3831
	* bfdlink.h (bfd_link_info): Rename dynamic to dynamic_list.
	Add dynamic and dynamic_data. 

ld/

2007-01-05 H.J. Lu  <hongjiu.lu@intel.com>

	PR ld/3831
	* ldlang.c (lang_process): Change link_info.dynamic to
	link_info.dynamic_list.
	(lang_append_dynamic_list): Likewise.
	* ldmain.c (main): Likewise.  Initialize link_info.dynamic and
	link_info.dynamic_data to FALSE.

	* lexsup.c (option_values): Add OPTION_DYNAMIC_LIST_DATA.
	(ld_options): --dynamic-list-data.
	(parse_args): Change link_info.dynamic to
	link_info.dynamic_list.  Set link_info.dynamic_data to TRUE for
	--dynamic-list-data.  Set link_info.dynamic to TRUE for
	--dynamuc-list*.

--- binutils/bfd/elf-bfd.h.data	2007-01-08 10:05:49.000000000 -0800
+++ binutils/bfd/elf-bfd.h	2007-01-08 10:05:49.000000000 -0800
@@ -1858,7 +1858,8 @@ extern int bfd_elf_link_record_local_dyn
   (struct bfd_link_info *, bfd *, long);
 
 extern void bfd_elf_link_mark_dynamic_symbol
-  (struct bfd_link_info *, struct elf_link_hash_entry *);
+  (struct bfd_link_info *, struct elf_link_hash_entry *,
+   Elf_Internal_Sym *);
 
 extern bfd_boolean _bfd_elf_close_and_cleanup
   (bfd *);
--- binutils/bfd/elflink.c.data	2007-01-08 10:05:49.000000000 -0800
+++ binutils/bfd/elflink.c	2007-01-08 17:42:35.000000000 -0800
@@ -454,14 +454,22 @@ bfd_elf_link_record_dynamic_symbol (stru
 
 void
 bfd_elf_link_mark_dynamic_symbol (struct bfd_link_info *info,
-				  struct elf_link_hash_entry *h)
+				  struct elf_link_hash_entry *h,
+				  Elf_Internal_Sym *sym)
 {
-  struct bfd_elf_dynamic_list *d = info->dynamic;
+  struct bfd_elf_dynamic_list *d = info->dynamic_list;
 
-  if (d == NULL || info->relocatable)
+  /* It may be called more than once on the same H.  */
+  if(h->dynamic || info->relocatable)
     return;
 
-  if ((*d->match) (&d->head, NULL, h->root.root.string))
+  if ((info->dynamic_data
+       && (h->type == STT_OBJECT
+	   || (sym != NULL
+	       && ELF_ST_TYPE (sym->st_info) == STT_OBJECT)))
+      || (d != NULL 
+	  && h->root.type == bfd_link_hash_new
+	  && (*d->match) (&d->head, NULL, h->root.root.string)))
     h->dynamic = 1;
 }
 
@@ -499,7 +507,7 @@ bfd_elf_record_link_assignment (bfd *out
 
   if (h->root.type == bfd_link_hash_new)
     {
-      bfd_elf_link_mark_dynamic_symbol (info, h);
+      bfd_elf_link_mark_dynamic_symbol (info, h, NULL);
       h->non_elf = 0;
     }
 
@@ -906,13 +914,17 @@ _bfd_elf_merge_symbol (bfd *abfd,
 	 || h->root.type == bfd_link_hash_warning)
     h = (struct elf_link_hash_entry *) h->root.u.i.link;
 
+  /* We have to check it for every instance since the first few may be
+     refereences and not all compilers emit symbol type for undefined
+     symbols.  */
+  bfd_elf_link_mark_dynamic_symbol (info, h, sym);
+
   /* If we just created the symbol, mark it as being an ELF symbol.
      Other than that, there is nothing to do--there is no merge issue
      with a newly defined symbol--so we just return.  */
 
   if (h->root.type == bfd_link_hash_new)
     {
-      bfd_elf_link_mark_dynamic_symbol (info, h);
       h->non_elf = 0;
       return TRUE;
     }
--- binutils/include/bfdlink.h.data	2006-10-30 15:25:51.000000000 -0800
+++ binutils/include/bfdlink.h	2007-01-08 10:05:49.000000000 -0800
@@ -340,6 +340,13 @@ struct bfd_link_info
      caching ELF symbol buffer.  */
   unsigned int reduce_memory_overheads: 1;
 
+  /* TRUE if all data symbols should be dynamic.  */
+  unsigned int dynamic_data: 1;
+
+  /* TRUE if some symbols have to be dynamic, controlled by
+     --dynamic-list command line options.  */
+  unsigned int dynamic: 1;
+
   /* What to do with unresolved symbols in an object file.
      When producing executables the default is GENERATE_ERROR.
      When producing shared libraries the default is IGNORE.  The
@@ -440,7 +447,7 @@ struct bfd_link_info
   bfd_vma relro_start, relro_end;
 
   /* List of symbols should be dynamic.  */
-  struct bfd_elf_dynamic_list *dynamic;
+  struct bfd_elf_dynamic_list *dynamic_list;
 };
 
 /* This structures holds a set of callback functions.  These are
--- binutils/ld/ldlang.c.data	2007-01-08 10:05:49.000000000 -0800
+++ binutils/ld/ldlang.c	2007-01-08 10:05:49.000000000 -0800
@@ -5732,8 +5732,8 @@ void
 lang_process (void)
 {
   /* Finalize dynamic list.  */
-  if (link_info.dynamic)
-    lang_finalize_version_expr_head (&link_info.dynamic->head);
+  if (link_info.dynamic_list)
+    lang_finalize_version_expr_head (&link_info.dynamic_list->head);
 
   current_target = default_target;
 
@@ -7047,13 +7047,13 @@ lang_add_unique (const char *name)
 void
 lang_append_dynamic_list (struct bfd_elf_version_expr *dynamic)
 {
-  if (link_info.dynamic)
+  if (link_info.dynamic_list)
     {
       struct bfd_elf_version_expr *tail;
       for (tail = dynamic; tail->next != NULL; tail = tail->next)
 	;
-      tail->next = link_info.dynamic->head.list;
-      link_info.dynamic->head.list = dynamic;
+      tail->next = link_info.dynamic_list->head.list;
+      link_info.dynamic_list->head.list = dynamic;
     }
   else
     {
@@ -7062,7 +7062,7 @@ lang_append_dynamic_list (struct bfd_elf
       d = xcalloc (1, sizeof *d);
       d->head.list = dynamic;
       d->match = lang_vers_match;
-      link_info.dynamic = d;
+      link_info.dynamic_list = d;
     }
 }
 
--- binutils/ld/ldmain.c.data	2006-10-30 15:25:51.000000000 -0800
+++ binutils/ld/ldmain.c	2007-01-08 10:05:49.000000000 -0800
@@ -318,7 +318,9 @@ main (int argc, char **argv)
   link_info.warn_shared_textrel = FALSE;
   link_info.gc_sections = FALSE;
   link_info.print_gc_sections = FALSE;
-  link_info.dynamic = NULL;
+  link_info.dynamic = FALSE;
+  link_info.dynamic_list = NULL;
+  link_info.dynamic_data = FALSE;
   link_info.reduce_memory_overheads = FALSE;
 
   config.maxpagesize = 0;
--- binutils/ld/lexsup.c.data	2006-10-30 15:25:51.000000000 -0800
+++ binutils/ld/lexsup.c	2007-01-08 10:05:49.000000000 -0800
@@ -109,6 +109,7 @@ enum option_values
   OPTION_VERSION_EXPORTS_SECTION,
   OPTION_DYNAMIC_LIST,
   OPTION_DYNAMIC_LIST_CPP_TYPEINFO,
+  OPTION_DYNAMIC_LIST_DATA,
   OPTION_WARN_COMMON,
   OPTION_WARN_CONSTRUCTORS,
   OPTION_WARN_FATAL,
@@ -507,6 +508,8 @@ static const struct ld_option ld_options
     '\0', NULL, N_("Use C++ typeinfo dynamic list"), TWO_DASHES },
   { {"dynamic-list", required_argument, NULL, OPTION_DYNAMIC_LIST},
     '\0', N_("FILE"), N_("Read dynamic list"), TWO_DASHES },
+  { {"dynamic-list-data", no_argument, NULL, OPTION_DYNAMIC_LIST_DATA},
+    '\0', NULL, N_("Add data symbols to dynamic list"), TWO_DASHES },
   { {"warn-common", no_argument, NULL, OPTION_WARN_COMMON},
     '\0', NULL, N_("Warn about duplicate common symbols"), TWO_DASHES },
   { {"warn-constructors", no_argument, NULL, OPTION_WARN_CONSTRUCTORS},
@@ -1244,8 +1247,13 @@ parse_args (unsigned argc, char **argv)
 	     .exports sections.  */
 	  command_line.version_exports_section = optarg;
 	  break;
+	case OPTION_DYNAMIC_LIST_DATA:
+	  link_info.dynamic_data = TRUE;
+	  link_info.dynamic = TRUE;
+	  break;
 	case OPTION_DYNAMIC_LIST_CPP_TYPEINFO:
 	  lang_append_dynamic_list_cpp_typeinfo ();
+	  link_info.dynamic = TRUE;
 	  break;
 	case OPTION_DYNAMIC_LIST:
 	  /* This option indicates a small script that only specifies
@@ -1260,6 +1268,7 @@ parse_args (unsigned argc, char **argv)
 	    parser_input = input_dynamic_list;
 	    yyparse ();
 	  }
+	  link_info.dynamic = TRUE;
 	  break;
 	case OPTION_WARN_COMMON:
 	  config.warn_common = TRUE;
-------------- next part --------------
#include <set>
#include <cstdio>
#include <cstdlib>

using namespace std;

int
main(int argc, char **argv)
{
    int n = argc == 2 ? atoi(argv[1]) : 10000;
    set<int> s;
    for(int i = 0; i < n; i++)
        s.insert(rand());
    for(int i = 0; i < 10000; i++){
        for(set<int>::iterator it = s.begin(); it != s.end(); ++it){
            if(*it < 0) return 1;
        }
    }
//    printf("set size: %d\n", (int)s.size());
}
More information about the Binutils mailing list