Don't cause ICEs when auto profile file is not found with checking

Currently, on a checking enabled compiler when -fauto-profile does
not find the profile feedback file it errors out with assertation
failures. Add proper errors for this case.

gcc/:

2016-05-30  Andi Kleen  <ak@linux.intel.com>

	* auto-profile.c (read_profile): Replace asserts with errors
	when file does not exist.
	* gcov-io.c (gcov_read_words): Dito.

From-SVN: r236894

gcc/ChangeLog

+2016-05-30  Andi Kleen  <ak@linux.intel.com>
+
+	* auto-profile.c (read_profile): Replace asserts with errors
+	when file does not exist.
+	* gcov-io.c (gcov_read_words): Dito.
+
 2016-05-30  Jan Hubicka  <hubicka@ucw.cz>
 	
 	* tree-cfg.c (print_loop): Print likely upper bounds.

gcc/auto-profile.c

@@ -884,16 +884,25 @@ static void
 read_profile (void)
 {
   if (gcov_open (auto_profile_file, 1) == 0)
-    error ("Cannot open profile file %s.", auto_profile_file);
+    {
+      error ("Cannot open profile file %s.", auto_profile_file);
+      return;
+    }
 
   if (gcov_read_unsigned () != GCOV_DATA_MAGIC)
-    error ("AutoFDO profile magic number does not mathch.");
+    {
+      error ("AutoFDO profile magic number does not match.");
+      return;
+    }
 
   /* Skip the version number.  */
   unsigned version = gcov_read_unsigned ();
   if (version != AUTO_PROFILE_VERSION)
-    error ("AutoFDO profile version %u does match %u.",
-           version, AUTO_PROFILE_VERSION);
+    {
+      error ("AutoFDO profile version %u does match %u.",
+	     version, AUTO_PROFILE_VERSION);
+      return;
+    }
 
   /* Skip the empty integer.  */
   gcov_read_unsigned ();
@@ -901,19 +910,28 @@ read_profile (void)
   /* string_table.  */
   afdo_string_table = new string_table ();
   if (!afdo_string_table->read())
-    error ("Cannot read string table from %s.", auto_profile_file);
+    {
+      error ("Cannot read string table from %s.", auto_profile_file);
+      return;
+    }
 
   /* autofdo_source_profile.  */
   afdo_source_profile = autofdo_source_profile::create ();
   if (afdo_source_profile == NULL)
-    error ("Cannot read function profile from %s.", auto_profile_file);
+    {
+      error ("Cannot read function profile from %s.", auto_profile_file);
+      return;
+    }
 
   /* autofdo_module_profile.  */
   fake_read_autofdo_module_profile ();
 
   /* Read in the working set.  */
   if (gcov_read_unsigned () != GCOV_TAG_AFDO_WORKING_SET)
-    error ("Cannot read working set from %s.", auto_profile_file);
+    {
+      error ("Cannot read working set from %s.", auto_profile_file);
+      return;
+    }
 
   /* Skip the length of the section.  */
   gcov_read_unsigned ();

gcc/gcov-io.c

@@ -493,7 +493,9 @@ gcov_read_words (unsigned words)
   const gcov_unsigned_t *result;
   unsigned excess = gcov_var.length - gcov_var.offset;
 
-  gcov_nonruntime_assert (gcov_var.mode > 0);
+  if (gcov_var.mode <= 0)
+    return NULL;
+
   if (excess < words)
     {
       gcov_var.start += gcov_var.offset;