[google] Add options to pattern match function name for hotness attributes

[Dehao Chen]

I've updated the patch using deferred option.

http://codereview.appspot.com/6281047

Thanks,
Dehao

The new patch:

2012-06-01  Dehao Chen  <dehao@google.com>

	* gcc/cgraph.c (cgraph_match_attribute_by_name): New function.
	(cgraph_node): Add attribute to function decl.
	* gcc/opts-global.c (add_attribute_list_to_vector): New function.
	(handle_common_deferred_options): Handle new options.
	* gcc/opts.c (common_handle_option): Handle new options.
	* gcc/opts.h (attribute_pair): New type.
	* gcc/common.opt (flag_function_attribute_list): New option.
Index: gcc/doc/invoke.texi
===================================================================
--- gcc/doc/invoke.texi	(revision 188050)
+++ gcc/doc/invoke.texi	(working copy)
@@ -362,7 +362,8 @@
 -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-attribute-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 +8586,10 @@
 specify this option and you may have problems with debugging if
 you specify both this option and @option{-g}.

+@item -ffunction-attribute-list
+@opindex ffunction-attribute-list
+List of function name patterns that will be applied specified 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)
@@ -99,6 +99,7 @@
 #include "ipa-utils.h"
 #include "lto-streamer.h"
 #include "l-ipo.h"
+#include "opts.h"

 const char * const ld_plugin_symbol_resolution_names[]=
 {
@@ -520,6 +521,32 @@
     }
 }

+/* Match FNDECL's name with user specified patterns. If match is found, add
+   attributes 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 void
+cgraph_match_attribute_by_name (tree fndecl)
+{
+  unsigned i;
+  attribute_pair_p p;
+  const char *name = lang_hooks.decl_printable_name(fndecl, 0);
+
+  if (!name)
+    return;
+
+  FOR_EACH_VEC_ELT (attribute_pair_p, function_attribute_list, i, p)
+    {
+      char *n = p->name;
+      int len = strlen (n);
+      if ((n[len - 1] == '*' && !strncmp (name, n, len - 1))
+          || !strcmp (name, n))
+        decl_attributes (&fndecl, tree_cons (
+            get_identifier (p->attribute), NULL, NULL), 0);
+    }
+}
+
 /* Return cgraph node assigned to DECL.  Create new one when needed.  */

 struct cgraph_node *
@@ -554,6 +581,7 @@
       node->origin->nested = node;
     }
   cgraph_add_assembler_hash_node (node);
+  cgraph_match_attribute_by_name (decl);
   return node;
 }

Index: gcc/opts.c
===================================================================
--- gcc/opts.c	(revision 188050)
+++ gcc/opts.c	(working copy)
@@ -1647,6 +1647,10 @@
       /* Deferred.  */
       break;

+    case OPT_ffunction_attribute_list_:
+      /* Deferred.  */
+      break;
+
     case OPT_fsched_verbose_:
 #ifdef INSN_SCHEDULING
       /* Handled with Var in common.opt.  */
Index: gcc/opts.h
===================================================================
--- gcc/opts.h	(revision 188050)
+++ gcc/opts.h	(working copy)
@@ -272,6 +272,15 @@
   struct cl_option_handler_func handlers[3];
 };

+typedef struct {
+  char *name;
+  char *attribute;
+} attribute_pair;
+typedef attribute_pair *attribute_pair_p;
+DEF_VEC_P(attribute_pair_p);
+DEF_VEC_ALLOC_P(attribute_pair_p,heap);
+extern VEC(attribute_pair_p,heap) *function_attribute_list;
+
 /* Input file names.  */

 extern const char **in_fnames;
Index: gcc/common.opt
===================================================================
--- gcc/common.opt	(revision 188050)
+++ gcc/common.opt	(working copy)
@@ -1242,6 +1242,10 @@
 Common Report Var(flag_function_sections)
 Place each function into its own section

+ffunction-attribute-list=
+Common Joined RejectNegative Var(common_deferred_options) Defer
+-ffunction-attribute-list=attribute:name,...  Add attribute to named functions
+
 fgcda=
 Common Joined RejectNegative Var(gcov_da_name)
 Set the gcov data file name.
Index: gcc/opts-global.c
===================================================================
--- gcc/opts-global.c	(revision 188050)
+++ gcc/opts-global.c	(working copy)
@@ -50,6 +50,8 @@
 const char **in_fnames;
 unsigned num_in_fnames;

+VEC(attribute_pair_p,heap) *function_attribute_list;
+
 /* Return a malloced slash-separated list of languages in MASK.  */

 static char *
@@ -79,6 +81,66 @@
   return result;
 }

+/* Add strings like attribute_str:name1,name2... to a char_pair_p vector.  */
+
+static void
+add_attribute_list_to_vector (void **pvec, const char *arg)
+{
+  char *tmp;
+  char *r;
+  char *w;
+  char *token_start;
+  char *attribute;
+  VEC(attribute_pair_p,heap) *vec = (VEC(attribute_pair_p,heap) *) *pvec;
+
+  /* We never free this string.  */
+  tmp = xstrdup (arg);
+  attribute = tmp;
+
+  for (r = tmp; *r != '\0' && *r != ':'; ++r)
+    ;
+
+  if (*r != ':')
+    return;
+
+  *r = '\0';
+  ++r;
+  w = r;
+  token_start = r;
+
+  while (*r != '\0')
+    {
+      if (*r == ',')
+	{
+	  attribute_pair_p p =
+	      (attribute_pair_p) xmalloc (sizeof (attribute_pair));
+	  p->name = token_start;
+	  p->attribute = attribute;
+	  *w++ = '\0';
+	  ++r;
+	  VEC_safe_push (attribute_pair_p, heap, vec, p);
+	  token_start = w;
+	}
+      if (*r == '\\' && r[1] == ',')
+	{
+	  *w++ = ',';
+	  r += 2;
+	}
+      else
+	*w++ = *r++;
+    }
+  if (*token_start != '\0')
+    {
+      attribute_pair_p p =
+	  (attribute_pair_p) xmalloc (sizeof (attribute_pair));
+      p->name = token_start;
+      p->attribute = attribute;
+      VEC_safe_push (attribute_pair_p, heap, vec, p);
+    }
+
+  *pvec = vec;
+}
+
 /* Complain that switch DECODED does not apply to this front end (mask
    LANG_MASK).  */

@@ -452,6 +514,10 @@
 	  set_random_seed (opt->arg);
 	  break;

+	case OPT_ffunction_attribute_list_:
+	  add_attribute_list_to_vector(&function_attribute_list, opt->arg);
+	  break;
+
 	case OPT_fstack_limit:
 	  /* The real switch is -fno-stack-limit.  */
 	  if (!opt->value)

On Sun, Jun 3, 2012 at 9:14 PM, Dehao Chen <dehao@google.com> wrote:
> Thank you guys for the comments, I'll update the patch to :
>
> 1. generalize the flag to enable other annotations such always_inline.
> 2. change to use deferred option.
>
> Thanks,
> Dehao
>
> On Sun, Jun 3, 2012 at 12:40 PM, Xinliang David Li <davidxl@google.com> wrote:
>> On Sat, Jun 2, 2012 at 11:11 AM, Jan Hubicka <hubicka@ucw.cz> wrote:
>>>> Actually Dehao also plans to teach the static predictor to understand
>>>> standard library functions more (e.g IO functions) and add more naming
>>>
>>> How this differ from annotating the library?
>>
>> I find them more suitable to be compiler heuristic than being
>> function's attribute -- attribute is a much stronger assertion.
>>
>>>
>>> There are indeed quite some possibilities to do about library calls....
>>>
>>> One thing I always wondered about is how to tell predictor that paths containing
>>> heavy IO functions don't need to be really opimized to death, since their execution
>>> time is dominated by the IO...
>>>
>>
>> Yes -- if branch predictor does the right thing and if function
>> splitter is powerful enough, the IO code can be outlined and optimized
>> for size :)
>>
>>
>>>> based heuristics such as 'error, success, failure, fatal etc).
>>>
>>> yeah, this is also mentioned by some branch prediction papers. It is bit kludgy
>>> in nature (i.e. it won't understand programs written in Czech language) but it
>>> is an heuristics after all.
>>>
>>
>> right.
>>
>> thanks,
>>
>> David
>>
>>> Honza
>>>>
>>>> thanks,
>>>>
>>>> David
>>>>
>>>> > Honza
>>>> >>
>>>> >> thanks,
>>>> >>
>>>> >> David
>>>> >> > Honza