Implement tagging of profiler log event blocks.

src/checks.h

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 107 matching lines @@
 
 
 // Helper function used by the CHECK function when given string
 // arguments.  Should not be called directly.
 static inline void CheckEqualsHelper(const char* file,
                                      int line,
                                      const char* expected_source,
                                      const char* expected,
                                      const char* value_source,
                                      const char* value) {
-  if (strcmp(expected, value) != 0) {
+  if ((expected == NULL && value != NULL) ||
+      (expected != NULL && value == NULL) ||
+      (expected != NULL && value != NULL && strcmp(expected, value) != 0)) {
     V8_Fatal(file, line,
              "CHECK_EQ(%s, %s) failed\n#   Expected: %s\n#   Found: %s",
              expected_source, value_source, expected, value);
   }
 }
 
 
 static inline void CheckNonEqualsHelper(const char* file,
                                         int line,
                                         const char* expected_source,
@@ skipping 136 matching lines @@
 
 
 #define ASSERT_TAG_ALIGNED(address) \
   ASSERT((reinterpret_cast<intptr_t>(address) & kHeapObjectTagMask) == 0)
 
 #define ASSERT_SIZE_TAG_ALIGNED(size) ASSERT((size & kHeapObjectTagMask) == 0)
 
 #define ASSERT_NOT_NULL(p)  ASSERT_NE(NULL, p)
 
 #endif  // V8_CHECKS_H_