Optimization for StringBuilder append boolean and null

src/java.base/share/classes/java/lang/AbstractStringBuilder.java

@@ -61,6 +61,7 @@
  */
 abstract sealed class AbstractStringBuilder implements Appendable, CharSequence
     permits StringBuilder, StringBuffer {
+
     /**
      * The value is used for character storage.
      */
@@ -635,18 +636,21 @@ public AbstractStringBuilder append(CharSequence s) {
     }
 
     private AbstractStringBuilder appendNull() {
-        ensureCapacityInternal(count + 4);
         int count = this.count;
+        ensureCapacityInternal(count + 4);
         byte[] val = this.value;
         if (isLatin1()) {
-            val[count++] = 'n';
-            val[count++] = 'u';
-            val[count++] = 'l';
-            val[count++] = 'l';
+            val[count] = 'n';
+            val[count + 1] = 'u';
+            val[count + 2] = 'l';
+            val[count + 3] = 'l';
         } else {
-            count = StringUTF16.putCharsAt(val, count, 'n', 'u', 'l', 'l');
+            StringUTF16.putChar(val, count, 'n');
+            StringUTF16.putChar(val, count + 1, 'u');
+            StringUTF16.putChar(val, count + 2, 'l');
+            StringUTF16.putChar(val, count + 3, 'l');
         }
-        this.count = count;
+        this.count = count + 4;
         return this;
     }
 
@@ -766,30 +770,38 @@ public AbstractStringBuilder append(char[] str, int offset, int len) {
      * @return  a reference to this object.
      */
     public AbstractStringBuilder append(boolean b) {
-        ensureCapacityInternal(count + (b ? 4 : 5));
         int count = this.count;
+        int spaceNeeded = count + (b ? 4 : 5);
+        ensureCapacityInternal(spaceNeeded);
         byte[] val = this.value;
         if (isLatin1()) {
             if (b) {
-                val[count++] = 't';
-                val[count++] = 'r';
-                val[count++] = 'u';
-                val[count++] = 'e';
+                val[count] = 't';
+                val[count + 1] = 'r';
+                val[count + 2] = 'u';
+                val[count + 3] = 'e';
             } else {
-                val[count++] = 'f';
-                val[count++] = 'a';
-                val[count++] = 'l';
-                val[count++] = 's';
-                val[count++] = 'e';
+                val[count] = 'f';
+                val[count + 1] = 'a';
+                val[count + 2] = 'l';
+                val[count + 3] = 's';
+                val[count + 4] = 'e';
             }
         } else {
             if (b) {
-                count = StringUTF16.putCharsAt(val, count, 't', 'r', 'u', 'e');
+                StringUTF16.putChar(val, count, 't');
+                StringUTF16.putChar(val, count + 1, 'r');
+                StringUTF16.putChar(val, count + 2, 'u');
+                StringUTF16.putChar(val, count + 3, 'e');
             } else {
-                count = StringUTF16.putCharsAt(val, count, 'f', 'a', 'l', 's', 'e');
+                StringUTF16.putChar(val, count, 'f');
+                StringUTF16.putChar(val, count + 1, 'a');
+                StringUTF16.putChar(val, count + 2, 'l');
+                StringUTF16.putChar(val, count + 3, 's');
+                StringUTF16.putChar(val, count + 4, 'e');
             }
         }
-        this.count = count;
+        this.count = spaceNeeded;
         return this;
     }
 

src/java.base/share/classes/java/lang/StringUTF16.java

@@ -1552,29 +1552,6 @@ public static boolean contentEquals(byte[] value, CharSequence cs, int len) {
         return true;
     }
 
-    public static int putCharsAt(byte[] value, int i, char c1, char c2, char c3, char c4) {
-        int end = i + 4;
-        checkBoundsBeginEnd(i, end, value);
-        putChar(value, i++, c1);
-        putChar(value, i++, c2);
-        putChar(value, i++, c3);
-        putChar(value, i++, c4);
-        assert(i == end);
-        return end;
-    }
-
-    public static int putCharsAt(byte[] value, int i, char c1, char c2, char c3, char c4, char c5) {
-        int end = i + 5;
-        checkBoundsBeginEnd(i, end, value);
-        putChar(value, i++, c1);
-        putChar(value, i++, c2);
-        putChar(value, i++, c3);
-        putChar(value, i++, c4);
-        putChar(value, i++, c5);
-        assert(i == end);
-        return end;
-    }
-
     public static char charAt(byte[] value, int index) {
         checkIndex(index, value);
         return getChar(value, index);

test/hotspot/jtreg/compiler/intrinsics/string/TestStringUTF16IntrinsicRangeChecks.java

@@ -108,13 +108,6 @@ public static void main(String[] args) throws Exception {
                 throw new AssertionError("append");
             }
 
-            putCharsAt(val2, -1, '1', '2', '3', '4');
-            putCharsAt(val2,  0, '1', '2', '3', '4');
-            putCharsAt(val2,  2, '1', '2', '3', '4');
-            putCharsAt(val2, -1, '1', '2', '3', '4', '5');
-            putCharsAt(val2,  0, '1', '2', '3', '4', '5');
-            putCharsAt(val2,  2, '1', '2', '3', '4', '5');
-
             reverse(valHigh, -1);
             reverse(valHigh,  2);
             reverse(valLow,  -1);
@@ -248,22 +241,6 @@ static void contentEquals(byte[] v, CharSequence cs, int len) {
         }
     }
 
-    static void putCharsAt(byte[] v, int i, char c1, char c2, char c3, char c4) {
-        try {
-            Helper.putCharsAt(v, i, c1, c2, c3, c4);
-            throw new AssertionError("putCharsAt");
-        } catch (IndexOutOfBoundsException io) {
-        }
-    }
-
-    static void putCharsAt(byte[] v, int i, char c1, char c2, char c3, char c4, char c5) {
-        try {
-            Helper.putCharsAt(v, i, c1, c2, c3, c4, c5);
-            throw new AssertionError("putCharsAt");
-        } catch (IndexOutOfBoundsException io) {
-        }
-    }
-
     static void reverse(byte[] v, int len) {
         try {
             Helper.reverse(v, len);

test/hotspot/jtreg/compiler/patches/java.base/java/lang/Helper.java

@@ -132,14 +132,6 @@ public static boolean contentEquals(byte[] value, CharSequence cs, int len) {
         return StringUTF16.contentEquals(value, cs, len);
     }
 
-    public static int putCharsAt(byte[] value, int i, char c1, char c2, char c3, char c4) {
-        return StringUTF16.putCharsAt(value, i, c1, c2, c3, c4);
-    }
-
-    public static int putCharsAt(byte[] value, int i, char c1, char c2, char c3, char c4, char c5) {
-        return StringUTF16.putCharsAt(value, i, c1, c2, c3, c4, c5);
-    }
-
     public static char charAt(byte[] value, int index) {
         return StringUTF16.charAt(value, index);
     }

test/micro/org/openjdk/bench/java/lang/StringBuilders.java

@@ -240,6 +240,53 @@ public String toStringCharWithBool8() {
     }
 
 
+    @Benchmark
+    public String toStringCharUTF16WithBool8() {
+        StringBuilder result = new StringBuilder()
+                .append('\u6e29');
+        result.append(true);
+        result.append(false);
+        result.append(true);
+        result.append(true);
+        result.append(false);
+        result.append(true);
+        result.append(false);
+        result.append(false);
+        return result.toString();
+    }
+
+
+    @Benchmark
+    public String toStringCharWithNull8() {
+        StringBuilder result = new StringBuilder();
+        result.append((String) null);
+        result.append((String) null);
+        result.append((String) null);
+        result.append((String) null);
+        result.append((String) null);
+        result.append((String) null);
+        result.append((String) null);
+        result.append((String) null);
+        return result.toString();
+    }
+
+
+    @Benchmark
+    public String toStringCharUTF16WithNull8() {
+        StringBuilder result = new StringBuilder()
+                .append('\u6e29');
+        result.append((String) null);
+        result.append((String) null);
+        result.append((String) null);
+        result.append((String) null);
+        result.append((String) null);
+        result.append((String) null);
+        result.append((String) null);
+        result.append((String) null);
+        return result.toString();
+    }
+
+
     @Benchmark
     public String toStringCharWithFloat8() {
         StringBuilder result = new StringBuilder();