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libjava optimized int->String conversion


I checked in the following (into the trunk only).  This optimizes
String.valueOf(int), Integer.toString(), and Stringbuffer.append(int)
to avoid needless allocation of temporary char[] buffers and Strings.
Instead, they use a stack-allocated 22-byte (11 jchars) buffer and the
new _Jv_FormatInt, as discussed in recent mail.

2001-05-21  Per Bothner  <per@bothner.com>

	* gcj/javaprims.h (_Jv_FormatInt):  New declaration.
	* java/lang/natString.cc (_JvFormatInt):  New primitive, with logic
	taken from old Integer.toString code.
	(Integer::valueOf):  Use _Jv_FormatInt.
	* java/lang/Integer.java (toString):  Just use call String.valueOf.
	* java/lang/Long.java (toString):  Fix typo in comment.
	* java/lang/String.java (valueOf(int)):  Make native.
	* java/lang/StringBuffer.java (append(int)):  Make native.
	* java/lang/natStringBuffer.cc:  New file, for append(jint).
	* Makefile.am (ant_source_files):  Add java/lang/natStringBuffer.cc.

Index: gcj/javaprims.h
===================================================================
RCS file: /cvs/gcc/gcc/libjava/gcj/javaprims.h,v
retrieving revision 1.19
diff -u -r1.19 javaprims.h
--- javaprims.h	2001/05/18 06:29:11	1.19
+++ javaprims.h	2001/05/22 04:35:07
@@ -371,6 +371,7 @@
 extern "C" jstring _Jv_AllocString(jsize) __attribute__((__malloc__));
 extern "C" jstring _Jv_NewString (const jchar*, jsize)
   __attribute__((__malloc__));
+extern jint _Jv_FormatInt (jchar* bufend, jint num);
 extern "C" jchar* _Jv_GetStringChars (jstring str);
 extern "C" jint _Jv_MonitorEnter (jobject);
 extern "C" jint _Jv_MonitorExit (jobject);
Index: java/lang/natString.cc
===================================================================
RCS file: /cvs/gcc/gcc/libjava/java/lang/natString.cc,v
retrieving revision 1.20
diff -u -r1.20 natString.cc
--- natString.cc	2001/04/10 22:46:11	1.20
+++ natString.cc	2001/05/22 04:35:08
@@ -341,6 +341,52 @@
   return dptr - buf;
 }
 
+/* Put printed (decimal) representation of NUM in a buffer.
+   BUFEND marks the end of the buffer, which must be at least 11 jchars long.
+   Returns the COUNT of jchars written.  The result is in
+   (BUFEND - COUNT) (inclusive) upto (BUFEND) (exclusive). */
+
+jint
+_Jv_FormatInt (jchar* bufend, jint num)
+{
+  register jchar* ptr = bufend;
+  jboolean isNeg;
+  if (num < 0)
+    {
+      isNeg = true;
+      num = -(num);
+      if (num < 0)
+	{
+	  // Must be MIN_VALUE, so handle this special case.
+	  // FIXME use 'unsigned jint' for num.
+	  *--ptr = '8';
+	  num = 214748364;
+	}
+      }
+    else
+      isNeg = false;
+
+    do
+      {
+        *--ptr = (jchar) ((int) '0' + (num % 10));
+        num /= 10;
+      }
+    while (num > 0);
+
+    if (isNeg)
+      *--ptr = '-';
+    return bufend - ptr;
+}
+
+jstring
+java::lang::String::valueOf (jint num)
+{
+  // Use an array large enough for "-2147483648"; i.e. 11 chars.
+  jchar buffer[11];
+  int i = _Jv_FormatInt (buffer+11, num);
+  return _Jv_NewString (buffer+11-i, i);
+}
+
 jstring
 _Jv_AllocString(jsize len)
 {
Index: java/lang/Integer.java
===================================================================
RCS file: /cvs/gcc/gcc/libjava/java/lang/Integer.java,v
retrieving revision 1.7
diff -u -r1.7 Integer.java
--- Integer.java	2001/02/19 03:43:12	1.7
+++ Integer.java	2001/05/22 04:35:08
@@ -267,35 +267,7 @@
 
   public static String toString(int num)
   {
-    // Use an arrary large enough for "-2147483648"; i.e. 11 chars.
-    char[] buffer = new char[11];
-    int i = 11;
-    boolean isNeg;
-    if (num < 0)
-      {
-        isNeg = true;
-        num = -(num);
-        if (num < 0)
-          {
-            // Must be MIN_VALUE, so handle this special case.
-            buffer[--i] = '8';
-            num = 214748364;
-          }
-      }
-    else
-      isNeg = false;
-
-    do
-      {
-        buffer[--i] = (char) ((int) '0' + (num % 10));
-        num /= 10;
-      }
-    while (num > 0);
-
-    if (isNeg)
-      buffer[--i] = '-';
-
-    return String.valueOf(buffer, i, 11-i);
+    return String.valueOf (num);
   }
 
   public static String toString(int num, int radix)
Index: java/lang/Long.java
===================================================================
RCS file: /cvs/gcc/gcc/libjava/java/lang/Long.java,v
retrieving revision 1.7
diff -u -r1.7 Long.java
--- Long.java	2001/02/19 03:43:12	1.7
+++ Long.java	2001/05/22 04:35:08
@@ -273,7 +273,7 @@
     if (num <= Integer.MAX_VALUE && num >= Integer.MIN_VALUE)
       return Integer.toString((int) num);
 
-    // Use an arrary large enough for "-9223372036854775808"; i.e. 11 chars.
+    // Use an array large enough for "-9223372036854775808"; i.e. 20 chars.
     char[] buffer = new char[20];
     int i = 20;
     boolean isNeg;
Index: java/lang/String.java
===================================================================
RCS file: /cvs/gcc/gcc/libjava/java/lang/String.java,v
retrieving revision 1.13
diff -u -r1.13 String.java
--- String.java	2001/04/01 21:54:09	1.13
+++ String.java	2001/05/22 04:35:09
@@ -319,10 +319,7 @@
 
   public static native String valueOf (char c);
 
-  public static String valueOf (int i)
-  {
-    return Integer.toString(i);
-  }
+  public static native String valueOf (int i);
 
   public static String valueOf (long l)
   {
Index: java/lang/StringBuffer.java
===================================================================
RCS file: /cvs/gcc/gcc/libjava/java/lang/StringBuffer.java,v
retrieving revision 1.10
diff -u -r1.10 StringBuffer.java
--- StringBuffer.java	2001/01/07 20:01:46	1.10
+++ StringBuffer.java	2001/05/22 04:35:09
@@ -89,10 +89,7 @@
    *  @return this <code>StringBuffer</code>.
    *  @see java.lang.String#valueOf(int)
    */
-  public StringBuffer append (int inum)
-  {
-    return append (String.valueOf(inum));
-  }
+  public native StringBuffer append (int inum);
 
   /** Append the <code>String</code> value of the argument to this <code>StringBuffer</code>.
    *  Uses <code>String.valueOf()</code> to convert to
Index: java/lang/natStringBuffer.cc
===================================================================
RCS file: natStringBuffer.cc
diff -N natStringBuffer.cc
--- /dev/null	Tue May  5 13:32:27 1998
+++ natStringBuffer.cc	Mon May 21 21:35:09 2001
@@ -0,0 +1,30 @@
+// natStringBuffer.cc - Implementation of java.lang.StringBuffer native methods.
+
+/* Copyright (C) 2001  Free Software Foundation
+
+   This file is part of libgcj.
+
+This software is copyrighted work licensed under the terms of the
+Libgcj License.  Please consult the file "LIBGCJ_LICENSE" for
+details.  */
+
+#include <config.h>
+#include <gcj/cni.h>
+#include <java/lang/StringBuffer.h>
+
+java::lang::StringBuffer*
+java::lang::StringBuffer::append (jint num)
+{
+  // Use an array large enough for "-2147483648"; i.e. 11 chars.
+  jchar buffer[11];
+  int i = _Jv_FormatInt (buffer+11, num);
+  JvSynchronize dummy (this);
+  jint needed = count + i;
+  ensureCapacity_unsynchronized (needed);
+  jchar* dst = elements (value) + count;
+  jchar* src = buffer+11-i;
+  while (--i >= 0)
+    *dst++ = *src++;
+  count = needed;
+  return this;
+}
Index: Makefile.am
===================================================================
RCS file: /cvs/gcc/gcc/libjava/Makefile.am,v
retrieving revision 1.144
diff -u -r1.144 Makefile.am
--- Makefile.am	2001/05/18 19:22:05	1.144
+++ Makefile.am	2001/05/22 04:35:10
@@ -1324,6 +1324,7 @@
 java/lang/natObject.cc \
 java/lang/natRuntime.cc	\
 java/lang/natString.cc \
+java/lang/natStringBuffer.cc \
 java/lang/natSystem.cc \
 java/lang/natThread.cc \
 java/lang/natThrowable.cc \
Index: Makefile.in
===================================================================
RCS file: /cvs/gcc/gcc/libjava/Makefile.in,v
retrieving revision 1.154
diff -u -r1.154 Makefile.in
--- Makefile.in	2001/05/18 19:22:05	1.154
+++ Makefile.in	2001/05/22 04:35:12
@@ -1068,6 +1068,7 @@
 java/lang/natObject.cc \
 java/lang/natRuntime.cc	\
 java/lang/natString.cc \
+java/lang/natStringBuffer.cc \
 java/lang/natSystem.cc \
 java/lang/natThread.cc \
 java/lang/natThrowable.cc \
@@ -1224,7 +1225,7 @@
 java/lang/natClass.lo java/lang/natClassLoader.lo \
 java/lang/natConcreteProcess.lo java/lang/natDouble.lo \
 java/lang/natFloat.lo java/lang/natMath.lo java/lang/natObject.lo \
-java/lang/natRuntime.lo java/lang/natString.lo java/lang/natSystem.lo \
+java/lang/natRuntime.lo java/lang/natString.lo java/lang/natStringBuffer.lo java/lang/natSystem.lo \
 java/lang/natThread.lo java/lang/natThrowable.lo \
 java/lang/reflect/natArray.lo java/lang/reflect/natConstructor.lo \
 java/lang/reflect/natField.lo java/lang/reflect/natMethod.lo \
@@ -1632,7 +1633,7 @@
 .deps/java/lang/natClassLoader.P .deps/java/lang/natConcreteProcess.P \
 .deps/java/lang/natDouble.P .deps/java/lang/natFloat.P \
 .deps/java/lang/natMath.P .deps/java/lang/natObject.P \
-.deps/java/lang/natRuntime.P .deps/java/lang/natString.P \
+.deps/java/lang/natRuntime.P .deps/java/lang/natString.P .deps/java/lang/natStringBuffer.P \
 .deps/java/lang/natSystem.P .deps/java/lang/natThread.P \
 .deps/java/lang/natThrowable.P .deps/java/lang/ref/PhantomReference.P \
 .deps/java/lang/ref/Reference.P .deps/java/lang/ref/ReferenceQueue.P \

-- 
	--Per Bothner
per@bothner.com   http://www.bothner.com/per/


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