8267870: Remove unnecessary char_converter during class loading

Reviewed-by: dholmes, iklam

src/hotspot/share/cds/classListParser.cpp

@@ -614,9 +614,8 @@ Klass* ClassListParser::load_current_class(Symbol* class_name_symbol, TRAPS) {
     // delegate to the correct loader (boot, platform or app) depending on
     // the package name.
 
-    Handle s = java_lang_String::create_from_symbol(class_name_symbol, CHECK_NULL);
     // ClassLoader.loadClass() wants external class name format, i.e., convert '/' chars to '.'
-    Handle ext_class_name = java_lang_String::externalize_classname(s, CHECK_NULL);
+    Handle ext_class_name = java_lang_String::externalize_classname(class_name_symbol, CHECK_NULL);
     Handle loader = Handle(THREAD, SystemDictionary::java_system_loader());
 
     JavaCalls::call_virtual(&result,

src/hotspot/share/classfile/javaAssertions.cpp

@@ -25,6 +25,7 @@
 #include "precompiled.hpp"
 #include "classfile/javaAssertions.hpp"
 #include "classfile/javaClasses.hpp"
+#include "classfile/symbolTable.hpp"
 #include "classfile/systemDictionary.hpp"
 #include "classfile/vmClasses.hpp"
 #include "classfile/vmSymbols.hpp"
@@ -127,7 +128,8 @@ oop JavaAssertions::createAssertionStatusDirectives(TRAPS) {
 }
 
 void JavaAssertions::fillJavaArrays(const OptionList* p, int len,
-objArrayHandle names, typeArrayHandle enabled, TRAPS) {
+                                    objArrayHandle names,
+                                    typeArrayHandle enabled, TRAPS) {
   // Fill in the parallel names and enabled (boolean) arrays.  Start at the end
   // of the array and work backwards, so the order of items in the arrays
   // matches the order on the command line (the list is in reverse order, since
@@ -135,8 +137,8 @@ objArrayHandle names, typeArrayHandle enabled, TRAPS) {
   int index;
   for (index = len - 1; p != 0; p = p->next(), --index) {
     assert(index >= 0, "length does not match list");
-    Handle s = java_lang_String::create_from_str(p->name(), CHECK);
-    s = java_lang_String::char_converter(s, JVM_SIGNATURE_SLASH, JVM_SIGNATURE_DOT, CHECK);
+    TempNewSymbol name = SymbolTable::new_symbol(p->name());
+    Handle s = java_lang_String::externalize_classname(name, CHECK);
     names->obj_at_put(index, s());
     enabled->bool_at_put(index, p->enabled());
   }

src/hotspot/share/classfile/javaClasses.cpp

@@ -469,70 +469,9 @@ char* java_lang_String::as_platform_dependent_str(Handle java_string, TRAPS) {
   return native_platform_string;
 }
 
-Handle java_lang_String::char_converter(Handle java_string, jchar from_char, jchar to_char, TRAPS) {
-  oop          obj    = java_string();
-  // Typical usage is to convert all '/' to '.' in string.
-  typeArrayOop value  = java_lang_String::value(obj);
-  int          length = java_lang_String::length(obj, value);
-  bool      is_latin1 = java_lang_String::is_latin1(obj);
-
-  // First check if any from_char exist
-  int index; // Declared outside, used later
-  for (index = 0; index < length; index++) {
-    jchar c = !is_latin1 ? value->char_at(index) :
-                  ((jchar) value->byte_at(index)) & 0xff;
-    if (c == from_char) {
-      break;
-    }
-  }
-  if (index == length) {
-    // No from_char, so do not copy.
-    return java_string;
-  }
-
-  // Check if result string will be latin1
-  bool to_is_latin1 = false;
-
-  // Replacement char must be latin1
-  if (CompactStrings && UNICODE::is_latin1(to_char)) {
-    if (is_latin1) {
-      // Source string is latin1 as well
-      to_is_latin1 = true;
-    } else if (!UNICODE::is_latin1(from_char)) {
-      // We are replacing an UTF16 char. Scan string to
-      // check if result can be latin1 encoded.
-      to_is_latin1 = true;
-      for (index = 0; index < length; index++) {
-        jchar c = value->char_at(index);
-        if (c != from_char && !UNICODE::is_latin1(c)) {
-          to_is_latin1 = false;
-          break;
-        }
-      }
-    }
-  }
-
-  // Create new UNICODE (or byte) buffer. Must handlize value because GC
-  // may happen during String and char array creation.
-  typeArrayHandle h_value(THREAD, value);
-  Handle string = basic_create(length, to_is_latin1, CHECK_NH);
-  typeArrayOop from_buffer = h_value();
-  typeArrayOop to_buffer = java_lang_String::value(string());
-
-  // Copy contents
-  for (index = 0; index < length; index++) {
-    jchar c = (!is_latin1) ? from_buffer->char_at(index) :
-                    ((jchar) from_buffer->byte_at(index)) & 0xff;
-    if (c == from_char) {
-      c = to_char;
-    }
-    if (!to_is_latin1) {
-      to_buffer->char_at_put(index, c);
-    } else {
-      to_buffer->byte_at_put(index, (jbyte) c);
-    }
-  }
-  return string;
+Handle java_lang_String::externalize_classname(Symbol* java_name, TRAPS) {
+  ResourceMark rm(THREAD);
+  return create_from_str(java_name->as_klass_external_name(), THREAD);
 }
 
 jchar* java_lang_String::as_unicode_string(oop java_string, int& length, TRAPS) {

src/hotspot/share/classfile/javaClasses.hpp

@@ -145,7 +145,6 @@ class java_lang_String : AllStatic {
   static oop    create_oop_from_str(const char* utf8_str, TRAPS);
   static Handle create_from_symbol(Symbol* symbol, TRAPS);
   static Handle create_from_platform_dependent_str(const char* str, TRAPS);
-  static Handle char_converter(Handle java_string, jchar from_char, jchar to_char, TRAPS);
 
   static void set_compact_strings(bool value);
 
@@ -228,10 +227,8 @@ class java_lang_String : AllStatic {
   static bool equals(oop str1, oop str2);
   static inline bool value_equals(typeArrayOop str_value1, typeArrayOop str_value2);
 
-  // Conversion between '.' and '/' formats
-  static Handle externalize_classname(Handle java_string, TRAPS) {
-    return char_converter(java_string, JVM_SIGNATURE_SLASH, JVM_SIGNATURE_DOT, THREAD);
-  }
+  // Conversion between '.' and '/' formats, and allocate a String from the result.
+  static Handle externalize_classname(Symbol* java_name, TRAPS);
 
   // Conversion
   static Symbol* as_symbol(oop java_string);

src/hotspot/share/classfile/systemDictionary.cpp

@@ -1309,9 +1309,8 @@ InstanceKlass* SystemDictionary::load_instance_class_impl(Symbol* class_name, Ha
                                jt->get_thread_stat()->perf_timers_addr(),
                                PerfClassTraceTime::CLASS_LOAD);
 
-    Handle s = java_lang_String::create_from_symbol(class_name, CHECK_NULL);
     // Translate to external class name format, i.e., convert '/' chars to '.'
-    Handle string = java_lang_String::externalize_classname(s, CHECK_NULL);
+    Handle string = java_lang_String::externalize_classname(class_name, CHECK_NULL);
 
     JavaValue result(T_OBJECT);