src/java.base/share/classes/java/nio/BufferMismatch.java

*** 32,41 ****
--- 32,43 ----
  final class BufferMismatch {
  
      static int mismatch(ByteBuffer a, int aOff, ByteBuffer b, int bOff, int length) {
          int i = 0;
          if (length > 7) {
+             if (a.get(aOff) != b.get(bOff))
+                 return 0;
              i = ArraysSupport.vectorizedMismatch(
                      a.base(), a.address + aOff,
                      b.base(), b.address + bOff,
                      length,
                      ArraysSupport.LOG2_ARRAY_BYTE_INDEX_SCALE);
*** 54,63 ****
--- 56,67 ----
          // Ensure only heap or off-heap buffer instances use the
          // vectorized mismatch. If either buffer is a StringCharBuffer
          // (order is null) then the slow path is taken
          if (length > 3 && a.charRegionOrder() == b.charRegionOrder()
              && a.charRegionOrder() != null && b.charRegionOrder() != null) {
+             if (a.get(aOff) != b.get(bOff))
+                 return 0;
              i = ArraysSupport.vectorizedMismatch(
                      a.base(), a.address + (aOff << ArraysSupport.LOG2_ARRAY_CHAR_INDEX_SCALE),
                      b.base(), b.address + (bOff << ArraysSupport.LOG2_ARRAY_CHAR_INDEX_SCALE),
                      length,
                      ArraysSupport.LOG2_ARRAY_CHAR_INDEX_SCALE);
*** 72,81 ****
--- 76,87 ----
      }
  
      static int mismatch(ShortBuffer a, int aOff, ShortBuffer b, int bOff, int length) {
          int i = 0;
          if (length > 3 && a.order() == b.order()) {
+             if (a.get(aOff) != b.get(bOff))
+                 return 0;
              i = ArraysSupport.vectorizedMismatch(
                      a.base(), a.address + (aOff << ArraysSupport.LOG2_ARRAY_SHORT_INDEX_SCALE),
                      b.base(), b.address + (bOff << ArraysSupport.LOG2_ARRAY_SHORT_INDEX_SCALE),
                      length,
                      ArraysSupport.LOG2_ARRAY_SHORT_INDEX_SCALE);
*** 90,99 ****
--- 96,107 ----
      }
  
      static int mismatch(IntBuffer a, int aOff, IntBuffer b, int bOff, int length) {
          int i = 0;
          if (length > 1 && a.order() == b.order()) {
+             if (a.get(aOff) != b.get(bOff))
+                 return 0;
              i = ArraysSupport.vectorizedMismatch(
                      a.base(), a.address + (aOff << ArraysSupport.LOG2_ARRAY_INT_INDEX_SCALE),
                      b.base(), b.address + (bOff << ArraysSupport.LOG2_ARRAY_INT_INDEX_SCALE),
                      length,
                      ArraysSupport.LOG2_ARRAY_INT_INDEX_SCALE);
*** 108,122 ****
--- 116,134 ----
      }
  
      static int mismatch(FloatBuffer a, int aOff, FloatBuffer b, int bOff, int length) {
          int i = 0;
          if (length > 1 && a.order() == b.order()) {
+             if (a.get(aOff) != b.get(bOff)) {
+                 i = 0;
+             } else {
                  i = ArraysSupport.vectorizedMismatch(
                          a.base(), a.address + (aOff << ArraysSupport.LOG2_ARRAY_FLOAT_INDEX_SCALE),
                          b.base(), b.address + (bOff << ArraysSupport.LOG2_ARRAY_FLOAT_INDEX_SCALE),
                          length,
                          ArraysSupport.LOG2_ARRAY_FLOAT_INDEX_SCALE);
+             }
              // Mismatched
              if (i >= 0) {
                  // Check if mismatch is not associated with two NaN values; and
                  // is not associated with +0 and -0
                  float av = a.get(aOff + i);
*** 144,153 ****
--- 156,167 ----
      }
  
      static int mismatch(LongBuffer a, int aOff, LongBuffer b, int bOff, int length) {
          int i = 0;
          if (length > 0 && a.order() == b.order()) {
+             if (a.get(aOff) != b.get(bOff))
+                 return 0;
              i = ArraysSupport.vectorizedMismatch(
                      a.base(), a.address + (aOff << ArraysSupport.LOG2_ARRAY_LONG_INDEX_SCALE),
                      b.base(), b.address + (bOff << ArraysSupport.LOG2_ARRAY_LONG_INDEX_SCALE),
                      length,
                      ArraysSupport.LOG2_ARRAY_LONG_INDEX_SCALE);
*** 161,175 ****
--- 175,193 ----
      }
  
      static int mismatch(DoubleBuffer a, int aOff, DoubleBuffer b, int bOff, int length) {
          int i = 0;
          if (length > 0 && a.order() == b.order()) {
+             if (a.get(aOff) != b.get(bOff)) {
+                 i = 0;
+             } else {
                  i = ArraysSupport.vectorizedMismatch(
                          a.base(), a.address + (aOff << ArraysSupport.LOG2_ARRAY_DOUBLE_INDEX_SCALE),
                          b.base(), b.address + (bOff << ArraysSupport.LOG2_ARRAY_DOUBLE_INDEX_SCALE),
                          length,
                          ArraysSupport.LOG2_ARRAY_DOUBLE_INDEX_SCALE);
+             }
              // Mismatched
              if (i >= 0) {
                  // Check if mismatch is not associated with two NaN values; and
                  // is not associated with +0 and -0
                  double av = a.get(aOff + i);