invoke.texi (-Wcoverage-mismatch): Document.

2007-01-25  Richard Guenther  <rguenther@suse.de>

	* doc/invoke.texi (-Wcoverage-mismatch): Document.
	* common.opt (-Wcoverage-mismatch): New warning option.
	* coverage.c (get_coverage_counts): Ignore coverage mismatch
	if -Wcoverage-mismatch is given.

	* gcc.dg/tree-prof/tree-prof.exp: Define _PROFILE_GENERATE
	and _PROFILE_USE.
	* gcc.dg/tree-prof/wcoverage-mismatch.c: New testcase.

From-SVN: r121169

gcc/ChangeLog

@@ -1,3 +1,10 @@
+2007-01-25  Richard Guenther  <rguenther@suse.de>
+
+	* doc/invoke.texi (-Wcoverage-mismatch): Document.
+	* common.opt (-Wcoverage-mismatch): New warning option.
+	* coverage.c (get_coverage_counts): Ignore coverage mismatch
+	if -Wcoverage-mismatch is given.
+
 2007-01-25  Razya Ladelsky  <razya@il.ibm.com>
 
         * ipa-cp.c (ipcp_insert_stage, ipcp_driver): Support for SSA. 

gcc/common.opt

@@ -197,6 +197,10 @@ Wvolatile-register-var
 Common Var(warn_register_var)
 Warn when a register variable is declared volatile
 
+Wcoverage-mismatch
+Common RejectNegative Var(warn_coverage_mismatch)
+Warn instead of error in case profiles in -fprofile-use do not match
+
 aux-info
 Common Separate
 -aux-info <file>	Emit declaration information into <file>

gcc/coverage.c

@@ -347,25 +347,46 @@ get_coverage_counts (unsigned counter, unsigned expected,
     {
       warning (0, "no coverage for function %qs found", IDENTIFIER_POINTER
 	       (DECL_ASSEMBLER_NAME (current_function_decl)));
-      return 0;
+      return NULL;
     }
 
   checksum = compute_checksum ();
-  if (entry->checksum != checksum)
+  if (entry->checksum != checksum
+      || entry->summary.num != expected)
     {
-      error ("coverage mismatch for function %qs while reading counter %qs",
-	     IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (current_function_decl)),
-	     ctr_names[counter]);
-      error ("checksum is %x instead of %x", entry->checksum, checksum);
-      return 0;
-    }
-  else if (entry->summary.num != expected)
-    {
-      error ("coverage mismatch for function %qs while reading counter %qs",
-	     IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (current_function_decl)),
-	     ctr_names[counter]);
-      error ("number of counters is %d instead of %d", entry->summary.num, expected);
-      return 0;
+      static int warned = 0;
+      const char *id = IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME
+			 (current_function_decl));
+
+      if (warn_coverage_mismatch)
+	warning (OPT_Wcoverage_mismatch, "coverage mismatch for function "
+		 "%qs while reading counter %qs", id, ctr_names[counter]);
+      else
+	error ("coverage mismatch for function %qs while reading counter %qs",
+	       id, ctr_names[counter]);
+
+      if (!inhibit_warnings)
+	{
+	  if (entry->checksum != checksum)
+	    inform ("checksum is %x instead of %x", entry->checksum, checksum);
+	  else
+	    inform ("number of counters is %d instead of %d",
+		    entry->summary.num, expected);
+	}
+
+      if (warn_coverage_mismatch
+	  && !inhibit_warnings
+	  && !warned++)
+	{
+	  inform ("coverage mismatch ignored due to -Wcoverage-mismatch");
+	  inform (flag_guess_branch_prob
+		  ? "execution counts estimated"
+		  : "execution counts assumed to be zero");
+	  if (!flag_guess_branch_prob)
+	    inform ("this can result in poorly optimized code");
+	}
+
+      return NULL;
     }
 
   if (summary)

gcc/doc/invoke.texi

@@ -225,7 +225,7 @@ Objective-C and Objective-C++ Dialects}.
 -w  -Wextra  -Wall  -Waggregate-return -Walways-true -Warray-bounds @gol
 -Wno-attributes -Wc++-compat -Wc++0x-compat -Wcast-align  -Wcast-qual  @gol
 -Wchar-subscripts -Wclobbered  -Wcomment @gol
--Wconversion  -Wno-deprecated-declarations @gol
+-Wconversion -Wcoverage-mismatch -Wno-deprecated-declarations @gol
 -Wdisabled-optimization  -Wno-div-by-zero  @gol
 -Wempty-body  -Wno-endif-labels @gol
 -Werror  -Werror-* -Werror-implicit-function-declaration @gol
@@ -2282,6 +2282,20 @@ diagnostic emitted, which indicates which command line option directly
 controls that diagnostic, when such an option is known to the
 diagnostic machinery.
 
+@item -Wcoverage-mismatch
+@opindex Wcoverage-mismatch
+Warn if feedback profiles do not match when using the
+@option{-fprofile-use} option.
+If a source file was changed between @option{-fprofile-gen} and
+@option{-fprofile-use}, the files with the profile feedback can fail
+to match the source file and GCC can not use the profile feedback
+information.  By default, GCC emits an error message in this case.
+The option @option{-Wcoverage-mismatch} emits a warning instead of an
+error.  GCC does not use appropriate feedback profiles, so using this
+option can result in poorly optimized code.  This option is useful
+only in the case of very minor changes such as bugfixes to an
+existing code-base.
+
 @end table
 
 @node Warning Options
@@ -5613,6 +5627,10 @@ generally profitable only with profile feedback available.
 The following options are enabled: @code{-fbranch-probabilities}, @code{-fvpt},
 @code{-funroll-loops}, @code{-fpeel-loops}, @code{-ftracer}
 
+By default, GCC emits an error message if the feedback profiles do not
+match the source code.  This error can be turned into a warning by using
+@option{-Wcoverage-mismatch}.  Note this may result in poorly optimized
+code.
 @end table
 
 The following options control compiler behavior regarding floating

gcc/testsuite/ChangeLog

@@ -1,3 +1,9 @@
+2007-01-25  Richard Guenther  <rguenther@suse.de>
+
+	* gcc.dg/tree-prof/tree-prof.exp: Define _PROFILE_GENERATE
+	and _PROFILE_USE.
+	* gcc.dg/tree-prof/wcoverage-mismatch.c: New testcase.
+
 2007-01-25  Razya Ladelsky  <razya@il.ibm.com>
 
         * gcc.dg/ipa/ipa-1.c: Update scan tree dump.

gcc/testsuite/gcc.dg/tree-prof/tree-prof.exp

@@ -41,8 +41,8 @@ load_lib profopt.exp
 # These are globals used by profopt-execute.  The first is options
 # needed to generate profile data, the second is options to use the
 # profile data.
-set profile_option "-fprofile-generate"
-set feedback_option "-fprofile-use"
+set profile_option "-fprofile-generate -D_PROFILE_GENERATE"
+set feedback_option "-fprofile-use -D_PROFILE_USE"
 
 foreach src [lsort [glob -nocomplain $srcdir/$subdir/*.c]] {
     # If we're only testing specific files and this isn't one of them, skip it.

gcc/testsuite/gcc.dg/tree-prof/wcoverage-mismatch.c

@@ -0,0 +1,20 @@
+/* { dg-options "-O2 -Wcoverage-mismatch -w" } */
+
+int __attribute__((noinline)) bar (void)
+{
+}
+
+int foo (int i)
+{
+#ifdef _PROFILE_USE
+  if (i)
+    bar ();
+#endif
+  return 0;
+}
+
+int main(int argc, char **argv)
+{
+  foo (argc);
+  return 0;
+}