diff --git a/buffer/src/main/java/io/netty/buffer/AbstractByteBuf.java b/buffer/src/main/java/io/netty/buffer/AbstractByteBuf.java
index 8e210a6cbf..4157356214 100644
--- a/buffer/src/main/java/io/netty/buffer/AbstractByteBuf.java
+++ b/buffer/src/main/java/io/netty/buffer/AbstractByteBuf.java
@@ -232,9 +232,13 @@ public abstract class AbstractByteBuf extends ByteBuf {
             throw new IllegalArgumentException(String.format(
                     "minWritableBytes: %d (expected: >= 0)", minWritableBytes));
         }
+        ensureWritable0(minWritableBytes);
+        return this;
+    }
 
+    private void ensureWritable0(int minWritableBytes) {
         if (minWritableBytes <= writableBytes()) {
-            return this;
+            return;
         }
 
         if (minWritableBytes > maxCapacity - writerIndex) {
@@ -248,7 +252,6 @@ public abstract class AbstractByteBuf extends ByteBuf {
 
         // Adjust to the new capacity.
         capacity(newCapacity);
-        return this;
     }
 
     @Override
@@ -543,21 +546,22 @@ public abstract class AbstractByteBuf extends ByteBuf {
         int nLong = length >>> 3;
         int nBytes = length & 7;
         for (int i = nLong; i > 0; i --) {
-            setLong(index, 0);
+            _setLong(index, 0);
             index += 8;
         }
         if (nBytes == 4) {
-            setInt(index, 0);
+            _setInt(index, 0);
+            // Not need to update the index as we not will use it after this.
         } else if (nBytes < 4) {
             for (int i = nBytes; i > 0; i --) {
-                setByte(index, (byte) 0);
+                _setByte(index, (byte) 0);
                 index ++;
             }
         } else {
-            setInt(index, 0);
+            _setInt(index, 0);
             index += 4;
             for (int i = nBytes - 4; i > 0; i --) {
-                setByte(index, (byte) 0);
+                _setByte(index, (byte) 0);
                 index ++;
             }
         }
@@ -566,9 +570,9 @@ public abstract class AbstractByteBuf extends ByteBuf {
 
     @Override
     public byte readByte() {
-        checkReadableBytes(1);
+        checkReadableBytes0(1);
         int i = readerIndex;
-        byte b = getByte(i);
+        byte b = _getByte(i);
         readerIndex = i + 1;
         return b;
     }
@@ -585,7 +589,7 @@ public abstract class AbstractByteBuf extends ByteBuf {
 
     @Override
     public short readShort() {
-        checkReadableBytes(2);
+        checkReadableBytes0(2);
         short v = _getShort(readerIndex);
         readerIndex += 2;
         return v;
@@ -607,7 +611,7 @@ public abstract class AbstractByteBuf extends ByteBuf {
 
     @Override
     public int readUnsignedMedium() {
-        checkReadableBytes(3);
+        checkReadableBytes0(3);
         int v = _getUnsignedMedium(readerIndex);
         readerIndex += 3;
         return v;
@@ -615,7 +619,7 @@ public abstract class AbstractByteBuf extends ByteBuf {
 
     @Override
     public int readInt() {
-        checkReadableBytes(4);
+        checkReadableBytes0(4);
         int v = _getInt(readerIndex);
         readerIndex += 4;
         return v;
@@ -628,7 +632,7 @@ public abstract class AbstractByteBuf extends ByteBuf {
 
     @Override
     public long readLong() {
-        checkReadableBytes(8);
+        checkReadableBytes0(8);
         long v = _getLong(readerIndex);
         readerIndex += 8;
         return v;
@@ -751,7 +755,7 @@ public abstract class AbstractByteBuf extends ByteBuf {
     @Override
     public ByteBuf writeByte(int value) {
         ensureAccessible();
-        ensureWritable(1);
+        ensureWritable0(1);
         _setByte(writerIndex++, value);
         return this;
     }
@@ -759,7 +763,7 @@ public abstract class AbstractByteBuf extends ByteBuf {
     @Override
     public ByteBuf writeShort(int value) {
         ensureAccessible();
-        ensureWritable(2);
+        ensureWritable0(2);
         _setShort(writerIndex, value);
         writerIndex += 2;
         return this;
@@ -768,7 +772,7 @@ public abstract class AbstractByteBuf extends ByteBuf {
     @Override
     public ByteBuf writeMedium(int value) {
         ensureAccessible();
-        ensureWritable(3);
+        ensureWritable0(3);
         _setMedium(writerIndex, value);
         writerIndex += 3;
         return this;
@@ -777,7 +781,7 @@ public abstract class AbstractByteBuf extends ByteBuf {
     @Override
     public ByteBuf writeInt(int value) {
         ensureAccessible();
-        ensureWritable(4);
+        ensureWritable0(4);
         _setInt(writerIndex, value);
         writerIndex += 4;
         return this;
@@ -786,7 +790,7 @@ public abstract class AbstractByteBuf extends ByteBuf {
     @Override
     public ByteBuf writeLong(long value) {
         ensureAccessible();
-        ensureWritable(8);
+        ensureWritable0(8);
         _setLong(writerIndex, value);
         writerIndex += 8;
         return this;
@@ -891,25 +895,32 @@ public abstract class AbstractByteBuf extends ByteBuf {
         }
 
         ensureWritable(length);
-        checkIndex(writerIndex, length);
+        int wIndex = writerIndex;
+        checkIndex(wIndex, length);
 
         int nLong = length >>> 3;
         int nBytes = length & 7;
         for (int i = nLong; i > 0; i --) {
-            writeLong(0);
+            _setLong(wIndex, 0);
+            wIndex += 8;
         }
         if (nBytes == 4) {
-            writeInt(0);
+            _setInt(wIndex, 0);
+            wIndex += 4;
         } else if (nBytes < 4) {
             for (int i = nBytes; i > 0; i --) {
-                writeByte((byte) 0);
+                _setByte(wIndex, (byte) 0);
+                wIndex++;
             }
         } else {
-            writeInt(0);
+            _setInt(wIndex, 0);
+            wIndex += 4;
             for (int i = nBytes - 4; i > 0; i --) {
-                writeByte((byte) 0);
+                _setByte(wIndex, (byte) 0);
+                wIndex++;
             }
         }
+        writerIndex = wIndex;
         return this;
     }
 
@@ -1117,19 +1128,12 @@ public abstract class AbstractByteBuf extends ByteBuf {
     }
 
     protected final void checkIndex(int index) {
-        ensureAccessible();
-        if (index < 0 || index >= capacity()) {
-            throw new IndexOutOfBoundsException(String.format(
-                    "index: %d (expected: range(0, %d))", index, capacity()));
-        }
+        checkIndex(index, 1);
     }
 
     protected final void checkIndex(int index, int fieldLength) {
         ensureAccessible();
-        if (fieldLength < 0) {
-            throw new IllegalArgumentException("length: " + fieldLength + " (expected: >= 0)");
-        }
-        if (index < 0 || index > capacity() - fieldLength) {
+        if (isInvalid(index, fieldLength, capacity())) {
             throw new IndexOutOfBoundsException(String.format(
                     "index: %d, length: %d (expected: range(0, %d))", index, fieldLength, capacity()));
         }
@@ -1137,7 +1141,7 @@ public abstract class AbstractByteBuf extends ByteBuf {
 
     protected final void checkSrcIndex(int index, int length, int srcIndex, int srcCapacity) {
         checkIndex(index, length);
-        if (srcIndex < 0 || srcIndex > srcCapacity - length) {
+        if (isInvalid(srcIndex, length, srcCapacity)) {
             throw new IndexOutOfBoundsException(String.format(
                     "srcIndex: %d, length: %d (expected: range(0, %d))", srcIndex, length, srcCapacity));
         }
@@ -1145,22 +1149,30 @@ public abstract class AbstractByteBuf extends ByteBuf {
 
     protected final void checkDstIndex(int index, int length, int dstIndex, int dstCapacity) {
         checkIndex(index, length);
-        if (dstIndex < 0 || dstIndex > dstCapacity - length) {
+        if (isInvalid(dstIndex, length, dstCapacity)) {
             throw new IndexOutOfBoundsException(String.format(
                     "dstIndex: %d, length: %d (expected: range(0, %d))", dstIndex, length, dstCapacity));
         }
     }
 
+    private static boolean isInvalid(int index, int length, int capacity) {
+        return (index | length | (index + length) | (capacity - (index + length))) < 0;
+    }
+
     /**
      * Throws an {@link IndexOutOfBoundsException} if the current
      * {@linkplain #readableBytes() readable bytes} of this buffer is less
      * than the specified value.
      */
     protected final void checkReadableBytes(int minimumReadableBytes) {
-        ensureAccessible();
         if (minimumReadableBytes < 0) {
             throw new IllegalArgumentException("minimumReadableBytes: " + minimumReadableBytes + " (expected: >= 0)");
         }
+        checkReadableBytes0(minimumReadableBytes);
+    }
+
+    private void checkReadableBytes0(int minimumReadableBytes) {
+        ensureAccessible();
         if (readerIndex > writerIndex - minimumReadableBytes) {
             throw new IndexOutOfBoundsException(String.format(
                     "readerIndex(%d) + length(%d) exceeds writerIndex(%d): %s",