This patch overloads GCC option -freorder-functions with -freoder-functions=*
which will invoke the linker plugin libfunction_reordering_plugin.so. For now,
the only accepted option is -freoder-functions=cgedge, where the functions
which are connected by hot callgraph edges are placed closer. When
-freorder-functions is specified without the '=', the original behaviour is
maintained. This patch also removes the -fcallgraph-profiles-sections option.
For context, the function_reordering_plugin is only available in gcc-4_6
branch. I am working on porting this to trunk and will send out a patch soon.
* cgraphbuild.c (remove_cgraph_callee_edges): Replace
flag_callgraph_profiles_sections with flag_reorder_functions.
* final.c (rest_of_handle_final): Ditto.
* configure: Regenerate.
* config.in: undef FRPLUGINSONAME.
* congifure.ac: Define FRPLUGINSONAME.
* config.host: Set host_function_reordering_plugin_soname.
* gcc.c: Invoke function_reordering linker plugin with
-freorder-functions=* option.
(set_func_reorder_linker_plugin_spec): New function.
(main): Call set_func_reorder_linker_plugin_spec when
-freorder-functions=* option is seen.
* common.opt (fcallgraph-profiles-sections): Remove.
(freorder-functions=): New option.
* function_reordering_plugin.c (register_claim_file_hook): New function
pointer.
(register_all_symbols_read_hook): Ditto.
(no_op): New global.
(out_file): Make static.
(is_api_exist): Make static.
(process_option): New function.
(onload): Return if no_op is set. Do not register handlers until
necessary.
Index: function_reordering_plugin/function_reordering_plugin.c
===================================================================
--- function_reordering_plugin/function_reordering_plugin.c (revision
185372)
+++ function_reordering_plugin/function_reordering_plugin.c (working copy)
@@ -64,6 +64,9 @@ enum ld_plugin_status claim_file_hook (const struc
int *claimed);
enum ld_plugin_status all_symbols_read_hook ();
+static ld_plugin_register_claim_file register_claim_file_hook = NULL;
+static ld_plugin_register_all_symbols_read
+ register_all_symbols_read_hook = NULL;
static ld_plugin_get_input_section_count get_input_section_count = NULL;
static ld_plugin_get_input_section_type get_input_section_type = NULL;
static ld_plugin_get_input_section_name get_input_section_name = NULL;
@@ -73,12 +76,16 @@ static ld_plugin_allow_section_ordering allow_sect
/* The file where the final function order will be stored.
It is "./final_layout.txt". It can be changed by passing
- new name to --plugin-opt */
+ new name to --plugin-opt as --plugin-opt "file=<name>".
+ To dump to stderr, say --plugin-opt "file=stderr". */
-char *out_file = "./final_layout.txt";
+static char *out_file = "./final_layout.txt";
-int is_api_exist = 0;
+static int is_api_exist = 0;
+/* The plugin does nothing when no-op is 1. */
+static int no_op = 0;
+
/* Copies new output file name out_file */
void get_filename (const char *name)
{
@@ -91,6 +98,39 @@ void get_filename (const char *name)
strcpy (out_file, name);
}
+/* Process options to plugin. Options with prefix "group=" are special.
+ They specify the type of grouping. The option "group=none" makes the
+ plugin do nothing. Options with prefix "file=" set the output file
+ where the final function order must be stored. */
+void
+process_option (const char *name)
+{
+ const char *option_group = "group=";
+ const char *option_file = "file=";
+
+ /* Check if option is "group=" */
+ if (strncmp (name, option_group, strlen (option_group)) == 0)
+ {
+ if (strcmp (name + strlen (option_group), "none") == 0)
+ no_op = 1;
+ else
+ no_op = 0;
+ return;
+ }
+
+ /* Check if option is "file=" */
+ if (strncmp (name, option_file, strlen (option_file)) == 0)
+ {
+ get_filename (name + strlen (option_file));
+ return;
+ }
+
+ /* Unknown option, set no_op to 1. */
+ no_op = 1;
+ fprintf (stderr, "Unknown option to function reordering plugin :%s\n",
+ name);
+}
+
/* Plugin entry point. */
enum ld_plugin_status
onload (struct ld_plugin_tv *tv)
@@ -105,14 +145,16 @@ onload (struct ld_plugin_tv *tv)
case LDPT_GOLD_VERSION:
break;
case LDPT_OPTION:
- get_filename (entry->tv_u.tv_string);
+ process_option (entry->tv_u.tv_string);
+ /* If no_op is set, do not do anything else. */
+ if (no_op) return LDPS_OK;
break;
case LDPT_REGISTER_CLAIM_FILE_HOOK:
- assert ((*entry->tv_u.tv_register_claim_file) (claim_file_hook) ==
LDPS_OK);
+ register_claim_file_hook = *entry->tv_u.tv_register_claim_file;
break;
case LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK:
- assert ((*entry->tv_u.tv_register_all_symbols_read)
(all_symbols_read_hook)
- == LDPS_OK);
+ register_all_symbols_read_hook
+ = *entry->tv_u.tv_register_all_symbols_read;
break;
case LDPT_GET_INPUT_SECTION_COUNT:
get_input_section_count = *entry->tv_u.tv_get_input_section_count;
@@ -137,14 +179,25 @@ onload (struct ld_plugin_tv *tv)
}
}
- if (get_input_section_count != NULL
+ assert (!no_op);
+
+ if (register_all_symbols_read_hook != NULL
+ && register_claim_file_hook != NULL
+ && get_input_section_count != NULL
&& get_input_section_type != NULL
&& get_input_section_name != NULL
&& get_input_section_contents != NULL
&& update_section_order != NULL
&& allow_section_ordering != NULL)
is_api_exist = 1;
+ else
+ return LDPS_OK;
+ /* Register handlers. */
+ assert ((*register_all_symbols_read_hook) (all_symbols_read_hook)
+ == LDPS_OK);
+ assert ((*register_claim_file_hook) (claim_file_hook)
+ == LDPS_OK);
return LDPS_OK;
}
@@ -161,9 +214,8 @@ claim_file_hook (const struct ld_plugin_input_file
(void) claimed;
- /* Silently return if the plugin APIs are not supported. */
- if (!is_api_exist)
- return LDPS_OK;
+ /* Plugin APIs are supported if this is called. */
+ assert (is_api_exist);
if (is_ordering_specified == 0)
{
@@ -221,9 +273,8 @@ all_symbols_read_hook (void)
unsigned int *shndx;
FILE *fp;
- /* Silently return if the plugin APIs are not supported. */
- if (!is_api_exist)
- return LDPS_OK;
+ /* Plugin APIs are supported if this is called. */
+ assert (is_api_exist);
if (is_callgraph_empty ())
return LDPS_OK;
Index: function_reordering_plugin/ChangeLog.google-4_6
===================================================================
--- function_reordering_plugin/ChangeLog.google-4_6 (revision 185372)
+++ function_reordering_plugin/ChangeLog.google-4_6 (working copy)
@@ -1,3 +1,15 @@
+2012-03-14 Sriraman Tallam <tmsri...@google.com>
+
+ * function_reordering_plugin.c (register_claim_file_hook): New function
+ pointer.
+ (register_all_symbols_read_hook): Ditto.
+ (no_op): New global.
+ (out_file): Make static.
+ (is_api_exist): Make static.
+ (process_option): New function.
+ (onload): Return if no_op is set. Do not register handlers until
+ necessary.
+
2012-02-25 Sriraman Tallam <tmsri...@google.com>
* function_reordering_plugin.c: Check for presence of elf.h.
Index: gcc/cgraphbuild.c
===================================================================
--- gcc/cgraphbuild.c (revision 185372)
+++ gcc/cgraphbuild.c (working copy)
@@ -703,10 +703,10 @@ extern bool cgraph_callee_edges_final_cleanup;
static unsigned int
remove_cgraph_callee_edges (void)
{
- /* The -fcallgraph-profiles-sections flag needs the call-graph preserved
+ /* The -freorder-functions=* flag needs the call-graph preserved
till pass_final. */
if (cgraph_callee_edges_final_cleanup
- && flag_callgraph_profiles_sections)
+ && flag_reorder_functions > 1)
return 0;
cgraph_node_remove_callees (cgraph_node (current_function_decl));
Index: gcc/configure
===================================================================
--- gcc/configure (revision 185372)
+++ gcc/configure (working copy)
@@ -4861,7 +4861,7 @@ fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $acx_cv_cc_gcc_supports_ada"
>&5
$as_echo "$acx_cv_cc_gcc_supports_ada" >&6; }
-if test x$GNATBIND != xno && test x$GNATMAKE != xno && test
x$acx_cv_cc_gcc_supports_ada != xno; then
+if test "x$GNATBIND" != xno && test "x$GNATMAKE" != xno && test
x$acx_cv_cc_gcc_supports_ada != xno; then
have_gnat=yes
else
have_gnat=no
@@ -11480,6 +11480,12 @@ esac
cat >>confdefs.h <<_ACEOF
+#define FRPLUGINSONAME "${host_function_reordering_plugin_soname}"
+_ACEOF
+
+
+
+cat >>confdefs.h <<_ACEOF
#define LTOPLUGINSONAME "${host_lto_plugin_soname}"
_ACEOF
@@ -17572,7 +17578,7 @@ else
lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
lt_status=$lt_dlunknown
cat > conftest.$ac_ext <<_LT_EOF
-#line 17575 "configure"
+#line 17581 "configure"
#include "confdefs.h"
#if HAVE_DLFCN_H
@@ -17678,7 +17684,7 @@ else
lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
lt_status=$lt_dlunknown
cat > conftest.$ac_ext <<_LT_EOF
-#line 17681 "configure"
+#line 17687 "configure"
#include "confdefs.h"
#if HAVE_DLFCN_H
Index: gcc/final.c
===================================================================
--- gcc/final.c (revision 185372)
+++ gcc/final.c (working copy)
@@ -4421,9 +4421,9 @@ rest_of_handle_final (void)
decl_fini_priority_lookup
(current_function_decl));
- /* With -fcallgraph-profiles-sections, add ".gnu.callgraph.text" section
+ /* With -freorder-functions=, add ".gnu.callgraph.text" section
for storing profiling information. */
- if (flag_callgraph_profiles_sections
+ if (flag_reorder_functions > 1
&& flag_profile_use
&& cgraph_node (current_function_decl) != NULL
&& (cgraph_node (current_function_decl))->callees != NULL)
Index: gcc/gcc.c
===================================================================
--- gcc/gcc.c (revision 185372)
+++ gcc/gcc.c (working copy)
@@ -663,6 +663,9 @@ proper position among the other output files. */
-plugin-opt=-fresolution=%u.res \
%{!nostdlib:%{!nodefaultlibs:%:pass-through-libs(%(link_gcc_c_sequence))}}
\
}"PLUGIN_COND_CLOSE" \
+ %{freorder-functions=*: \
+ -plugin %(func_reorder_linker_plugin_file) \
+ -plugin-opt=%(func_reorder_linker_plugin_opt)} \
%{flto|flto=*:%<fcompare-debug*} \
%{flto} %{flto=*} %l " LINK_PIE_SPEC \
"%{fuse-ld=gold:%{fuse-ld=bfd:%e-fuse-ld=gold and -fuse-ld=bfd may not be
used together}} \
@@ -717,6 +720,8 @@ static const char *endfile_spec = ENDFILE_SPEC;
static const char *startfile_spec = STARTFILE_SPEC;
static const char *linker_name_spec = LINKER_NAME;
static const char *linker_plugin_file_spec = "";
+static const char *func_reorder_linker_plugin_file_spec = "";
+static const char *func_reorder_linker_plugin_opt = "";
static const char *lto_wrapper_spec = "";
static const char *lto_gcc_spec = "";
static const char *link_command_spec = LINK_COMMAND_SPEC;
@@ -1206,6 +1211,10 @@ static struct spec_list static_specs[] =
INIT_STATIC_SPEC ("multilib_options", &multilib_options),
INIT_STATIC_SPEC ("linker", &linker_name_spec),
INIT_STATIC_SPEC ("linker_plugin_file", &linker_plugin_file_spec),
+ INIT_STATIC_SPEC ("func_reorder_linker_plugin_file",
+ &func_reorder_linker_plugin_file_spec),
+ INIT_STATIC_SPEC ("func_reorder_linker_plugin_opt",
+ &func_reorder_linker_plugin_opt),
INIT_STATIC_SPEC ("lto_wrapper", <o_wrapper_spec),
INIT_STATIC_SPEC ("lto_gcc", <o_gcc_spec),
INIT_STATIC_SPEC ("link_libgcc", &link_libgcc_spec),
@@ -6108,6 +6117,51 @@ compare_files (char *cmpfile[])
return ret;
}
+/* Set func_reorder_linker_plugin_file_spec and func_reorder_linker_plugin_opt
+ here. This is the linker plugin to do global function reordering and is
+ enabled with -freorder-functions=*. */
+
+static void
+set_func_reorder_linker_plugin_spec (void)
+{
+ int i;
+ const char *plugin_opt_none = "group=none";
+ const char *plugin_opt_cgedge = "group=cgedge";
+
+ /* Find the linker plugin that does function ordering. */
+ func_reorder_linker_plugin_file_spec = find_a_file (&exec_prefixes,
+ FRPLUGINSONAME, R_OK, false);
+
+ if (!func_reorder_linker_plugin_file_spec)
+ fatal_error ("-freorder-functions=*, but "
+ FRPLUGINSONAME " file not found");
+
+ func_reorder_linker_plugin_opt = plugin_opt_none;
+
+ /* Set linker plugin options here. Option ordering is also checked here.
+ -fno-reorder-functions or -freorder-functions should disable any
+ previous -freorder-functions=*. */
+ for (i = 0; (int) i < n_switches; i++)
+ {
+ /* Check for match with "-freorder-functions=cgedge". */
+ if (func_reorder_linker_plugin_opt != plugin_opt_cgedge
+ && !strcmp (switches[i].part1, "freorder-functions=cgedge"))
+ {
+ func_reorder_linker_plugin_opt = plugin_opt_cgedge;
+ continue;
+ }
+ /* Set option to none if it matches -fno-reorder-functions
+ or -freorder-functions */
+ if (func_reorder_linker_plugin_opt != plugin_opt_none
+ && (!strcmp (switches[i].part1, "fno-reorder-functions")
+ || !strcmp (switches[i].part1, "freorder-functions")))
+ {
+ func_reorder_linker_plugin_opt = plugin_opt_none;
+ continue;
+ }
+ }
+}
+
extern int main (int, char **);
int
@@ -6843,6 +6897,8 @@ warranty; not even for MERCHANTABILITY or FITNESS
const char *fuse_linker_plugin = "fuse-linker-plugin";
#endif
+ const char *freorder_functions_ = "freorder-functions=";
+
/* We'll use ld if we can't find collect2. */
if (! strcmp (linker_name_spec, "collect2"))
{
@@ -6866,6 +6922,12 @@ warranty; not even for MERCHANTABILITY or FITNESS
fatal_error ("-fuse-linker-plugin, but " LTOPLUGINSONAME " not
found");
}
lto_gcc_spec = argv[0];
+
+ /* The function reordering linker plugin will be loaded if the option
+ -freorder-functions= is present in the command-line. */
+ if (switch_matches (freorder_functions_,
+ freorder_functions_ + strlen (freorder_functions_),
1))
+ set_func_reorder_linker_plugin_spec ();
/* Rebuild the COMPILER_PATH and LIBRARY_PATH environment variables
for collect. */
Index: gcc/config.in
===================================================================
--- gcc/config.in (revision 185372)
+++ gcc/config.in (working copy)
@@ -1583,13 +1583,18 @@
#endif
+/* Define to the name of the function reordering plugin DSO that must be
+ passed to the linker's -plugin=LIB option. */
+#ifndef USED_FOR_TARGET
+#undef FRPLUGINSONAME
+#endif
+
/* Define to the name of the LTO plugin DSO that must be passed to the
linker's -plugin=LIB option. */
#ifndef USED_FOR_TARGET
#undef LTOPLUGINSONAME
#endif
-
/* Define to the sub-directory in which libtool stores uninstalled libraries.
*/
#ifndef USED_FOR_TARGET
Index: gcc/configure.ac
===================================================================
--- gcc/configure.ac (revision 185372)
+++ gcc/configure.ac (working copy)
@@ -1858,6 +1858,10 @@ case $use_collect2 in
;;
esac
+AC_DEFINE_UNQUOTED(FRPLUGINSONAME,"${host_function_reordering_plugin_soname}",
+[Define to the name of the function reordering plugin DSO that must be
+ passed to the linker's -plugin=LIB option.])
+
AC_DEFINE_UNQUOTED(LTOPLUGINSONAME,"${host_lto_plugin_soname}",
[Define to the name of the LTO plugin DSO that must be
passed to the linker's -plugin=LIB option.])
Index: gcc/ChangeLog.google-4_6
===================================================================
--- gcc/ChangeLog.google-4_6 (revision 185372)
+++ gcc/ChangeLog.google-4_6 (working copy)
@@ -1,3 +1,21 @@
+2012-03-14 Sriraman Tallam <tmsri...@google.com>
+
+ * cgraphbuild.c (remove_cgraph_callee_edges): Replace
+ flag_callgraph_profiles_sections with flag_reorder_functions.
+ * final.c (rest_of_handle_final): Ditto.
+ * configure: Regenerate.
+ * config.in: undef FRPLUGINSONAME.
+ * congifure.ac: Define FRPLUGINSONAME.
+ * config.host: Set host_function_reordering_plugin_soname.
+ * gcc.c: Invoke function_reordering linker plugin with
+ -freorder-functions=* option.
+ (set_func_reorder_linker_plugin_spec): New function.
+ (main): Call set_func_reorder_linker_plugin_spec when
+ -freorder-functions=* option is seen.
+ * common.opt: Add new option -freorder-functions=. Remove
+ -fcallgraph-profiles-sections.
+
+
2012-03-12 Sterling Augustine <saugust...@google.com>
Cary Coutant <ccout...@google.com>
Index: gcc/common.opt
===================================================================
--- gcc/common.opt (revision 185372)
+++ gcc/common.opt (working copy)
@@ -920,10 +920,6 @@ fcaller-saves
Common Report Var(flag_caller_saves) Optimization
Save registers around function calls
-fcallgraph-profiles-sections
-Common Report Var(flag_callgraph_profiles_sections) Init(0)
-Generate .note.callgraph.text sections listing callees and edge counts.
-
fcheck-data-deps
Common Report Var(flag_check_data_deps)
Compare the results of several data dependence analyzers.
@@ -1758,9 +1754,19 @@ Common Report Var(flag_reorder_blocks_and_partitio
Reorder basic blocks and partition into hot and cold sections
freorder-functions
-Common Report Var(flag_reorder_functions) Optimization
+Common Report Var(flag_reorder_functions,1) Init(0) Optimization
Reorder functions to improve code placement
+freorder-functions=
+Common Joined RejectNegative Enum(function_reorder)
Var(flag_reorder_functions) Init(0) Optimization
+-freorder-functions=[cgedge] Select the scheme for function reordering. This
invokes a linker plugin. Generate .note.callgraph.text sections listing
callees and edge counts.
+
+Enum
+Name(function_reorder) Type(int) UnknownError(unrecognized function reorder
value %qs)
+
+EnumValue
+Enum(function_reorder) String(cgedge) Value(2)
+
frerun-cse-after-loop
Common Report Var(flag_rerun_cse_after_loop) Optimization
Add a common subexpression elimination pass after loop optimizations
Index: gcc/config.host
===================================================================
--- gcc/config.host (revision 185372)
+++ gcc/config.host (working copy)
@@ -76,6 +76,7 @@ out_host_hook_obj=host-default.o
host_can_use_collect2=yes
use_long_long_for_widest_fast_int=no
host_lto_plugin_soname=liblto_plugin.so
+host_function_reordering_plugin_soname=libfunction_reordering_plugin.so
# Unsupported hosts list. Generally, only include hosts known to fail here,
# since we allow hosts not listed to be supported generically.
--
This patch is available for review at http://codereview.appspot.com/5825054
