Hi,
This patch adds 4 flags to enable user to type in a list of name
patterns. Compiler will match the function name with the given
patterns, and add "hot", "cold", "likely_hot", "likely_cold"
attributes to function declaration. The static branch prediction
checks if a basic block contains call to a annotated function, and set
the branch probability accordingly.
Bootstrapped and passed gcc testsuites.
Ok for google branches?
Thanks,
Dehao
gcc/ChangeLog.google-4_6
2012-06-01 Dehao Chen <de...@google.com>
* gcc/cgraph.c (cgraph_match_hotness_by_name): New function.
(cgraph_add_hotness_attribute): New function.
(cgraph_node): Add hotness attribute to function decl.
* gcc/opts.c (common_handle_option): Handle new options.
* gcc/predict.c (tree_bb_level_predictions): New prediction.
* gcc/predict.def (PRED_LIKELY_COLD_FUNCTION): New prediction.
* gcc/common.opt (flag_function_hot_list): New option.
(flag_function_cold_list): New option.
(flag_function_likely_hot_list): New option.
(flag_function_likely_cold_list): New option.
Index: gcc/doc/invoke.texi
===================================================================
--- gcc/doc/invoke.texi (revision 188050)
+++ gcc/doc/invoke.texi (working copy)
@@ -362,7 +362,9 @@
-fdelete-null-pointer-checks -fdse -fdevirtualize -fdse @gol
-fearly-inlining -fipa-sra -fexpensive-optimizations -ffast-math @gol
-ffinite-math-only -ffloat-store -fexcess-precision=@var{style} @gol
--fforward-propagate -ffp-contract=@var{style} -ffunction-sections @gol
+-fforward-propagate -ffp-contract=@var{style} @gol
+-ffunction-cold-list -ffunction-hot-list -ffunction-likely-cold-list @gol
+-ffunction-likely-hot-list -ffunction-sections @gol
-fgcse -fgcse-after-reload -fgcse-las -fgcse-lm -fgraphite-identity @gol
-fgcse-sm -fif-conversion -fif-conversion2 -findirect-inlining @gol
-finline-functions -finline-functions-called-once -finline-limit=@var{n} @gol
@@ -8585,6 +8587,22 @@
specify this option and you may have problems with debugging if
you specify both this option and @option{-g}.
+@item -ffunction-cold-list
+@opindex ffunction-cold-list
+List of function name patterns that will be applied "cold" attribute.
+
+@item -ffunction-hot-list
+@opindex ffunction-hot-list
+List of function name patterns that will be applied "hot" attribute.
+
+@item -ffunction-likely-cold-list
+@opindex ffunction-likely-cold-list
+List of function name patterns that will be applied "likely_cold" attribute.
+
+@item -ffunction-likely-hot-list
+@opindex ffunction-likely-hot-list
+List of function name patterns that will be applied "likely_hot" attribute.
+
@item -fbranch-target-load-optimize
@opindex fbranch-target-load-optimize
Perform branch target register load optimization before prologue / epilogue
Index: gcc/cgraph.c
===================================================================
--- gcc/cgraph.c (revision 188050)
+++ gcc/cgraph.c (working copy)
@@ -520,6 +520,70 @@
}
}
+typedef char *char_pointer;
+DEF_VEC_P(char_pointer);
+DEF_VEC_ALLOC_P(char_pointer,heap);
+
+/* Match FNDECL's name with PATTERNS. If matched, add HOTNESS attribute
+ to FNDECL.
+ name matches with pattern, iff one of the following conditions satisfy:
+ 1. strcmp (name, pattern) != 0
+ 2. pattern[len - 1] = '*' && strncmp (name, pattern, len - 1) != 0 */
+static bool
+cgraph_match_hotness_by_name (tree fndecl,
+ VEC(char_pointer, heap) *patterns,
+ const char *hotness)
+{
+ unsigned i;
+ char_pointer n;
+ const char *name = lang_hooks.decl_printable_name(fndecl, 0);
+
+ if (!name)
+ return false;
+
+ FOR_EACH_VEC_ELT (char_pointer, patterns, i, n)
+ {
+ int len = strlen (n);
+ if ((n[len - 1] == '*' && !strncmp (name, n, len - 1))
+ || !strcmp (name, n))
+ {
+ decl_attributes (&fndecl, tree_cons (
+ get_identifier (hotness), NULL, NULL), 0);
+ return true;
+ }
+ }
+ return false;
+}
+
+/* Add hotness attributes to FNDECL. */
+static void
+cgraph_add_hotness_attribute (tree fndecl)
+{
+ if (lookup_attribute ("cold", DECL_ATTRIBUTES (fndecl))
+ || lookup_attribute ("hot", DECL_ATTRIBUTES (fndecl))
+ || lookup_attribute ("likely_cold", DECL_ATTRIBUTES (fndecl))
+ || lookup_attribute ("likely_hot", DECL_ATTRIBUTES (fndecl)))
+ return;
+
+ if (cgraph_match_hotness_by_name (fndecl,
+ (VEC(char_pointer, heap) *) flag_function_cold_list, "cold"))
+ return;
+
+ if (cgraph_match_hotness_by_name (fndecl,
+ (VEC(char_pointer, heap) *) flag_function_hot_list, "hot"))
+ return;
+
+ if (cgraph_match_hotness_by_name (fndecl,
+ (VEC(char_pointer, heap) *) flag_function_likely_cold_list,
+ "likely_cold"))
+ return;
+
+ if (cgraph_match_hotness_by_name (fndecl,
+ (VEC(char_pointer, heap) *) flag_function_likely_hot_list,
+ "likely_hot"))
+ return;
+}
+
/* Return cgraph node assigned to DECL. Create new one when needed. */
struct cgraph_node *
@@ -554,6 +618,7 @@
node->origin->nested = node;
}
cgraph_add_assembler_hash_node (node);
+ cgraph_add_hotness_attribute (decl);
return node;
}
Index: gcc/opts.c
===================================================================
--- gcc/opts.c (revision 188050)
+++ gcc/opts.c (working copy)
@@ -1539,6 +1539,26 @@
(&opts->x_flag_instrument_functions_exclude_files, arg);
break;
+ case OPT_ffunction_hot_list_:
+ add_comma_separated_to_vector
+ (&opts->x_flag_function_hot_list, arg);
+ break;
+
+ case OPT_ffunction_cold_list_:
+ add_comma_separated_to_vector
+ (&opts->x_flag_function_cold_list, arg);
+ break;
+
+ case OPT_ffunction_likely_hot_list_:
+ add_comma_separated_to_vector
+ (&opts->x_flag_function_likely_hot_list, arg);
+ break;
+
+ case OPT_ffunction_likely_cold_list_:
+ add_comma_separated_to_vector
+ (&opts->x_flag_function_likely_cold_list, arg);
+ break;
+
case OPT_fmessage_length_:
pp_set_line_maximum_length (dc->printer, value);
break;
Index: gcc/predict.c
===================================================================
--- gcc/predict.c (revision 188050)
+++ gcc/predict.c (working copy)
@@ -2070,11 +2070,22 @@
predict_paths_leading_to (bb, PRED_NORETURN,
NOT_TAKEN);
decl = gimple_call_fndecl (stmt);
- if (decl
- && lookup_attribute ("cold",
- DECL_ATTRIBUTES (decl)))
- predict_paths_leading_to (bb, PRED_COLD_FUNCTION,
- NOT_TAKEN);
+ if (decl)
+ {
+ tree attr = DECL_ATTRIBUTES (decl);
+ if (lookup_attribute ("cold", attr))
+ predict_paths_leading_to (bb, PRED_COLD_FUNCTION,
+ NOT_TAKEN);
+ else if (lookup_attribute ("hot", attr))
+ predict_paths_leading_to (bb, PRED_COLD_FUNCTION,
+ TAKEN);
+ else if (lookup_attribute ("likely_cold", attr))
+ predict_paths_leading_to (bb, PRED_LIKELY_COLD_FUNCTION,
+ NOT_TAKEN);
+ else if (lookup_attribute ("likely_hot", attr))
+ predict_paths_leading_to (bb, PRED_LIKELY_COLD_FUNCTION,
+ TAKEN);
+ }
}
else if (gimple_code (stmt) == GIMPLE_PREDICT)
{
Index: gcc/ChangeLog.google-4_6
===================================================================
--- gcc/ChangeLog.google-4_6 (revision 188050)
+++ gcc/ChangeLog.google-4_6 (working copy)
@@ -1,3 +1,16 @@
+2012-06-01 Dehao Chen <de...@google.com>
+
+ * gcc/cgraph.c (cgraph_match_hotness_by_name): New function.
+ (cgraph_add_hotness_attribute): New function.
+ (cgraph_node): Add hotness attribute to function decl.
+ * gcc/opts.c (common_handle_option): Handle new options.
+ * gcc/predict.c (tree_bb_level_predictions): New prediction.
+ * gcc/predict.def (PRED_LIKELY_COLD_FUNCTION): New prediction.
+ * gcc/common.opt (flag_function_hot_list): New option.
+ (flag_function_cold_list): New option.
+ (flag_function_likely_hot_list): New option.
+ (flag_function_likely_cold_list): New option.
+
2012-05-30 Cary Coutant <ccout...@google.com>
* gcc/dwarf2out.c (index_location_lists): Don't index location
Index: gcc/predict.def
===================================================================
--- gcc/predict.def (revision 188050)
+++ gcc/predict.def (working copy)
@@ -76,6 +76,10 @@
DEF_PREDICTOR (PRED_COLD_FUNCTION, "cold function call", PROB_VERY_LIKELY,
PRED_FLAG_FIRST_MATCH)
+/* Branch to basic block containing call marked by likely_cold
function attribute. */
+DEF_PREDICTOR (PRED_LIKELY_COLD_FUNCTION, "likely cold function call",
+ HITRATE (75), PRED_FLAG_FIRST_MATCH)
+
/* Loopback edge is taken. */
DEF_PREDICTOR (PRED_LOOP_BRANCH, "loop branch", HITRATE (86),
PRED_FLAG_FIRST_MATCH)
Index: gcc/common.opt
===================================================================
--- gcc/common.opt (revision 188050)
+++ gcc/common.opt (working copy)
@@ -92,6 +92,20 @@
Variable
void *flag_instrument_functions_exclude_files
+; These four are VEC(char_p,heap) * that indicate function hotness.
+
+Variable
+void *flag_function_hot_list
+
+Variable
+void *flag_function_cold_list
+
+Variable
+void *flag_function_likely_hot_list
+
+Variable
+void *flag_function_likely_cold_list
+
; Generic structs (e.g. templates not explicitly specialized)
; may not have a compilation unit associated with them, and so
; may need to be treated differently from ordinary structs.
@@ -1242,6 +1256,22 @@
Common Report Var(flag_function_sections)
Place each function into its own section
+ffunction-hot-list=
+Common RejectNegative Joined
+-ffunction-hot-list=name,... Predict listed functions as hot
+
+ffunction-cold-list=
+Common RejectNegative Joined
+-ffunction-cold-list=name,... Predict listed functions as cold
+
+ffunction-likely-hot-list=
+Common RejectNegative Joined
+-ffunction-likely-hot-list=name,... Predict listed functions as likely_hot
+
+ffunction-likely-cold-list=
+Common RejectNegative Joined
+-ffunction-likely-cold-list=name,... Predict listed functions as likely_cold
+
fgcda=
Common Joined RejectNegative Var(gcov_da_name)
Set the gcov data file name.
