Add --trace-hydrogen-filter flag.

src/objects.cc

Index: src/objects.cc
diff --git a/src/objects.cc b/src/objects.cc
index daa5a4a5bdad825e7d73fc42531df9e23ac848b6..2a5fea22ee8b2be93e441c241fa4cc9ccac1a843 100644
--- a/src/objects.cc
+++ b/src/objects.cc
@@ -9032,6 +9032,23 @@ void String::PrintOn(FILE* file) {
 }
 
 
+bool String::PassesFilter(const char* raw_filter) {
+  if (*raw_filter == '*') return true;
+  Vector<const char> filter = CStrVector(raw_filter);
+  if (filter.length() == 0) return this->length() == 0;
+  if (filter[0] != '-' && this->IsUtf8EqualTo(filter)) return true;
+  if (filter[0] == '-' &&
+      !this->IsUtf8EqualTo(filter.SubVector(1, filter.length()))) {
+    return true;
+  }
+  if (filter[filter.length() - 1] == '*' &&
+      this->IsUtf8EqualTo(filter.SubVector(0, filter.length() - 1), true)) {
+    return true;
+  }
+  return false;
+}
+
+
 static void TrimEnumCache(Heap* heap, Map* map, DescriptorArray* descriptors) {
   int live_enum = map->EnumLength();
   if (live_enum == Map::kInvalidEnumCache) {
@@ -9621,30 +9638,7 @@ Context* JSFunction::NativeContextFromLiterals(FixedArray* literals) {
 
 
 bool JSFunction::PassesHydrogenFilter() {
-  String* name = shared()->DebugName();
-  // The filter string is a pattern that matches functions in this way:
-  //   "*"      all; the default
-  //   "-"      all but the top-level function
-  //   "-name"  all but the function "name"
-  //   ""       only the top-level function
-  //   "name"   only the function "name"
-  //   "name*"  only functions starting with "name"
-  if (*FLAG_hydrogen_filter != '*') {
-    Vector<const char> filter = CStrVector(FLAG_hydrogen_filter);
-    if (filter.length() == 0) return name->length() == 0;
-    if (filter[0] != '-' && name->IsUtf8EqualTo(filter)) return true;
-    if (filter[0] == '-' &&
-        !name->IsUtf8EqualTo(filter.SubVector(1, filter.length()))) {
-      return true;
-    }
-    if (filter[filter.length() - 1] == '*' &&
-        name->IsUtf8EqualTo(filter.SubVector(0, filter.length() - 1), true)) {
-      return true;
-    }
-    return false;
-  }
-
-  return true;
+  return shared()->DebugName()->PassesFilter(FLAG_hydrogen_filter);
 }