--- old/src/java.base/share/classes/java/lang/AbstractStringBuilder.java	2017-03-22 23:53:50.000000000 +0300
+++ new/src/java.base/share/classes/java/lang/AbstractStringBuilder.java	2017-03-22 23:53:49.000000000 +0300
@@ -36,6 +36,7 @@
 import static java.lang.String.LATIN1;
 import static java.lang.String.checkIndex;
 import static java.lang.String.checkOffset;
+import static java.lang.String.checkBoundsBeginEnd;
 
 /**
  * A mutable sequence of characters.
@@ -307,6 +308,8 @@
      *             sequence.
      */
     public int codePointAt(int index) {
+        int count = this.count;
+        byte[] value = this.value;
         checkIndex(index, count);
         if (isLatin1()) {
             return value[index] & 0xff;
@@ -560,7 +563,7 @@
             val[count++] = 'l';
             val[count++] = 'l';
         } else {
-            checkOffset(count + 4, val.length >> 1);
+            checkBoundsBeginEnd(count, count + 4, val.length >> 1);
             StringUTF16.putChar(val, count++, 'n');
             StringUTF16.putChar(val, count++, 'u');
             StringUTF16.putChar(val, count++, 'l');
@@ -695,13 +698,13 @@
             }
         } else {
             if (b) {
-                checkOffset(count + 4, val.length >> 1);
+                checkBoundsBeginEnd(count, count + 4, val.length >> 1);
                 StringUTF16.putChar(val, count++, 't');
                 StringUTF16.putChar(val, count++, 'r');
                 StringUTF16.putChar(val, count++, 'u');
                 StringUTF16.putChar(val, count++, 'e');
             } else {
-                checkOffset(count + 5, val.length >> 1);
+                checkBoundsBeginEnd(count, count + 5, val.length >> 1);
                 StringUTF16.putChar(val, count++, 'f');
                 StringUTF16.putChar(val, count++, 'a');
                 StringUTF16.putChar(val, count++, 'l');
@@ -755,16 +758,17 @@
      * @return  a reference to this object.
      */
     public AbstractStringBuilder append(int i) {
+        int count = this.count;
         int spaceNeeded = count + Integer.stringSize(i);
         ensureCapacityInternal(spaceNeeded);
         if (isLatin1()) {
             Integer.getChars(i, spaceNeeded, value);
         } else {
             byte[] val = this.value;
-            checkOffset(spaceNeeded, val.length >> 1);
+            checkBoundsBeginEnd(count, spaceNeeded, val.length >> 1);
             Integer.getCharsUTF16(i, spaceNeeded, val);
         }
-        count = spaceNeeded;
+        this.count = spaceNeeded;
         return this;
     }
 
@@ -781,16 +785,17 @@
      * @return  a reference to this object.
      */
     public AbstractStringBuilder append(long l) {
+        int count = this.count;
         int spaceNeeded = count + Long.stringSize(l);
         ensureCapacityInternal(spaceNeeded);
         if (isLatin1()) {
             Long.getChars(l, spaceNeeded, value);
         } else {
             byte[] val = this.value;
-            checkOffset(spaceNeeded, val.length >> 1);
+            checkBoundsBeginEnd(count, spaceNeeded, val.length >> 1);
             Long.getCharsUTF16(l, spaceNeeded, val);
         }
-        count = spaceNeeded;
+        this.count = spaceNeeded;
         return this;
     }
 
@@ -843,6 +848,7 @@
      *             greater than {@code end}.
      */
     public AbstractStringBuilder delete(int start, int end) {
+        int count = this.count;
         if (end > count) {
             end = count;
         }
@@ -850,7 +856,7 @@
         int len = end - start;
         if (len > 0) {
             shift(end, -len);
-            count -= len;
+            this.count = count - len;
         }
         return this;
     }
@@ -925,6 +931,7 @@
      *             greater than {@code end}.
      */
     public AbstractStringBuilder replace(int start, int end, String str) {
+        int count = this.count;
         if (end > count) {
             end = count;
         }
@@ -933,7 +940,7 @@
         int newCount = count + len - (end - start);
         ensureCapacityInternal(newCount);
         shift(end, newCount - count);
-        count = newCount;
+        this.count = newCount;
         putStringAt(start, str);
         return this;
     }
@@ -1422,6 +1429,10 @@
      *          or {@code -1} if there is no such occurrence.
      */
     public int indexOf(String str, int fromIndex) {
+        byte[] value = this.value;
+        int count = this.count;
+        byte coder = this.coder;
+        checkOffset(count, value.length >> coder);
         return String.indexOf(value, coder, count, str, fromIndex);
     }
 
@@ -1462,6 +1473,10 @@
      *          or {@code -1} if there is no such occurrence.
      */
     public int lastIndexOf(String str, int fromIndex) {
+        byte[] value = this.value;
+        int count = this.count;
+        byte coder = this.coder;
+        checkOffset(count, value.length >> coder);
         return String.lastIndexOf(value, coder, count, str, fromIndex);
     }