PATCH RFC: More control over which functions are instrumented

[Ian Lance Taylor <iant at google dot com>]

We've had a -finstrument-functions option for a while, which inserts
calls to __cyg_profile_func_enter and __cyg_profile_func_exit at the
start and end of each function.  This can be handy, but it is rather
less handy in practice with C++.  The issue is simply that there are a
bunch of inline functions which it is uninteresting to instrument, and
these functions come from standard headers so you can't really avoid
compiling them with -finstrument-functions.

This patch was developed a while back by Yaz Saito at Google.  It adds
two new options: -finstrument-functions-exclude-file-list and
-finstrument-functions-exclude-function-list which give more control
over which functions are instrumented.

This patch is all middle-end, which is in my bailiwick, but I'd like
to see whether there are any comments on this approach.

Bootstrapped and tested on i686-pc-linux-gnu.

Ian


2007-08-01  Yaz Saito  <saito@google.com>
	    Ian Lance Taylor  <iant@google.com>

	* common.opt (finstrument-functions-exclude-function-list): New
	option.
	(finstrument-functions-exclude-file-list): New option.
	* opts.c (char_p): Define and DEF_VEC.
	(flag_instrument_functions_exclude_functions): New static
	variable.
	(flag_instrument_functions_exclude_files): New static variable.
	(add_instrument_functions_exclude_list): New static function.
	(flag_instrument_functions_exclude_p): New function.
	(common_handle_option): Handle new options.
	* flags.h (flag_instrument_functions_exclude_p): Declare.
	* gimplify.c (gimplify_function_tree): Call
	flag_instrument_functions_exclude_p.
	* doc/invoke.texi (Option Summary): Mention new options.
	(Code Gen Options): Document new options.


Index: doc/invoke.texi
===================================================================
--- doc/invoke.texi	(revision 127073)
+++ doc/invoke.texi	(working copy)
@@ -810,6 +810,8 @@ See S/390 and zSeries Options.
 -fnon-call-exceptions  -funwind-tables @gol
 -fasynchronous-unwind-tables @gol
 -finhibit-size-directive  -finstrument-functions @gol
+-finstrument-functions-exclude-function-list=@var{sym},@var{sym},@dots{} @gol
+-finstrument-functions-exclude-file-list=@var{file},@var{file},@dots{} @gol
 -fno-common  -fno-ident @gol
 -fpcc-struct-return  -fpic  -fPIC -fpie -fPIE @gol
 -fno-jump-tables @gol
@@ -14664,6 +14666,37 @@ interrupt routines, and any functions fr
 cannot safely be called (perhaps signal handlers, if the profiling
 routines generate output or allocate memory).
 
+@item -finstrument-functions-exclude-file-list=@var{file},@var{file},@dots{}
+@opindex finstrument-functions-exclude-file-list
+
+Set the list of functions that are excluded from instrumentation (see
+the description of @code{-finstrument-functions}).  If the file that
+contains a function definition matches with one of @var{file}, then
+that function is not instrumented.  The match is done on substrings:
+if the @var{file} parameter is a substring of the file name, it is
+considered to be a match.
+
+For example,
+@code{-finstrument-functions-exclude-file-list=/bits/stl,include/sys}
+will exclude any inline function defined in files whose pathnames
+contain @code{/bits/stl} or @code{include/sys}.
+
+If, for some reason, you want to include letter @code{','} in one of
+@var{sym}, write @code{'\,'}. For example,
+@code{-finstrument-functions-exclude-file-list='\,\,tmp'}
+(note the single quote surrounding the option).
+
+@item -finstrument-functions-exclude-function-list=@var{sym},@var{sym},@dots{}
+@opindex finstrument-functions-exclude-function-list
+
+This is similar to @code{-finstrument-functions-exclude-file-list},
+but this option sets the list of function names to be excluded from
+instrumentation.  The function name to be matched is its user-visible
+name, such as @code{vector<int> blah(const vector<int> &)}, not the
+internal mangled name (e.g., @code{_Z4blahRSt6vectorIiSaIiEE}).  The
+match is done on substrings: if the @var{sym} parameter is a substring
+of the function name, it is considered to be a match.
+
 @item -fstack-check
 @opindex fstack-check
 Generate code to verify that you do not go beyond the boundary of the
Index: flags.h
===================================================================
--- flags.h	(revision 127073)
+++ flags.h	(working copy)
@@ -281,6 +281,10 @@ extern bool flag_speculative_prefetching
 #define abi_version_at_least(N) \
   (flag_abi_version == 0 || flag_abi_version >= (N))
 
+/* Return whether the function should be excluded from
+   instrumentation.  */
+extern bool flag_instrument_functions_exclude_p (tree fndecl);
+
 /* True if the given mode has a NaN representation and the treatment of
    NaN operands is important.  Certain optimizations, such as folding
    x * 0 into 0, are not correct for NaN operands, and are normally
Index: opts.c
===================================================================
--- opts.c	(revision 127073)
+++ opts.c	(working copy)
@@ -353,6 +353,15 @@ static bool flag_unroll_loops_set, flag_
 static bool flag_value_profile_transformations_set;
 static bool flag_peel_loops_set, flag_branch_probabilities_set;
 
+/* Functions excluded from profiling.  */
+
+typedef char *char_p; /* For DEF_VEC_P.  */
+DEF_VEC_P(char_p);
+DEF_VEC_ALLOC_P(char_p,heap);
+
+static VEC(char_p,heap) *flag_instrument_functions_exclude_functions;
+static VEC(char_p,heap) *flag_instrument_functions_exclude_files;
+
 /* Input file names.  */
 const char **in_fnames;
 unsigned num_in_fnames;
@@ -602,6 +611,87 @@ add_input_filename (const char *filename
   in_fnames[num_in_fnames - 1] = filename;
 }
 
+/* Add functions or file names to a vector of names to exclude from
+   instrumentation.  */
+
+static void
+add_instrument_functions_exclude_list (VEC(char_p,heap) **pvec,
+				       const char* arg)
+{
+  char *tmp;
+  char *r;
+  char *w;
+  char *token_start;
+
+  /* We never free this string.  */
+  tmp = xstrdup (arg);
+
+  r = tmp;
+  w = tmp;
+  token_start = tmp;
+
+  while (*r != '\0')
+    {
+      if (*r == ',')
+	{
+	  *w++ = '\0';
+	  ++r;
+	  VEC_safe_push (char_p, heap, *pvec, token_start);
+	  token_start = w;
+	}
+      if (*r == '\\' && r[1] == ',')
+	{
+	  *w++ = ',';
+	  r += 2;
+	}
+      else
+	*w++ = *r++;
+    }
+  if (*token_start != '\0')
+    VEC_safe_push (char_p, heap, *pvec, token_start);
+}
+
+/* Return whether we should exclude FNDECL from instrumentation.  */
+
+bool
+flag_instrument_functions_exclude_p (tree fndecl)
+{
+  if (VEC_length (char_p, flag_instrument_functions_exclude_functions) > 0)
+    {
+      const char *name;
+      int i;
+      char *s;
+
+      name = lang_hooks.decl_printable_name (fndecl, 0);
+      for (i = 0;
+	   VEC_iterate (char_p, flag_instrument_functions_exclude_functions,
+			i, s);
+	   ++i)
+	{
+	  if (strstr (name, s) != NULL)
+	    return true;
+	}
+    }
+
+  if (VEC_length (char_p, flag_instrument_functions_exclude_files) > 0)
+    {
+      const char *name;
+      int i;
+      char *s;
+
+      name = DECL_SOURCE_FILE (fndecl);
+      for (i = 0;
+	   VEC_iterate (char_p, flag_instrument_functions_exclude_files, i, s);
+	   ++i)
+	{
+	  if (strstr (name, s) != NULL)
+	    return true;
+	}
+    }
+
+  return false;
+}
+
 /* Decode and handle the vector of command line options.  LANG_MASK
    contains has a single bit set representing the current
    language.  */
@@ -1474,6 +1564,16 @@ common_handle_option (size_t scode, cons
       set_param_value ("max-inline-insns-auto", value / 2);
       break;
 
+    case OPT_finstrument_functions_exclude_function_list_:
+      add_instrument_functions_exclude_list
+	(&flag_instrument_functions_exclude_functions, arg);
+      break;
+
+    case OPT_finstrument_functions_exclude_file_list_:
+      add_instrument_functions_exclude_list
+	(&flag_instrument_functions_exclude_files, arg);
+      break;
+
     case OPT_fmessage_length_:
       pp_set_line_maximum_length (global_dc->printer, value);
       break;
Index: gimplify.c
===================================================================
--- gimplify.c	(revision 127073)
+++ gimplify.c	(working copy)
@@ -6494,7 +6494,8 @@ gimplify_function_tree (tree fndecl)
      catch the exit hook.  */
   /* ??? Add some way to ignore exceptions for this TFE.  */
   if (flag_instrument_function_entry_exit
-      && ! DECL_NO_INSTRUMENT_FUNCTION_ENTRY_EXIT (fndecl))
+      && !DECL_NO_INSTRUMENT_FUNCTION_ENTRY_EXIT (fndecl)
+      && !flag_instrument_functions_exclude_p (fndecl))
     {
       tree tf, x, bind;
 
Index: common.opt
===================================================================
--- common.opt	(revision 127073)
+++ common.opt	(working copy)
@@ -575,6 +575,14 @@ finstrument-functions
 Common Report Var(flag_instrument_function_entry_exit)
 Instrument function entry and exit with profiling calls
 
+finstrument-functions-exclude-function-list=
+Common RejectNegative Joined
+-finstrument-functions-exclude-function-list=name,...  Do not instrument listed functions
+
+finstrument-functions-exclude-file-list=
+Common RejectNegative Joined
+-finstrument-functions-exclude-file-list=filename,...  Do not instrument functions listed in files
+
 fipa-cp
 Common Report Var(flag_ipa_cp) Optimization
 Perform Interprocedural constant propagation