FULL PRODUCT VERSION :
java version "1.7.0_51"
Java(TM) SE Runtime Environment (build 1.7.0_51-b13)
Java HotSpot(TM) Client VM (build 24.51-b03, mixed mode, sharing)

ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows [Version 6.1.7601] (Windows 7)

A DESCRIPTION OF THE PROBLEM :
Pattern$BnM.optimize will optimize a Pattern$Slice or Pattern$SliceS (match a fixed string) to use Boyer-Moore algorithm. However, due to a bug in the type check, only Pattern$Slice (BMP version) is optimized; Pattern$SliceS (supplementary version) is never optimized.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1) Write a pattern that matches a fixed string, which contains supplementary characters. There must be >= 4 code points.
2) Access the internal structure of the Pattern via reflection. Access the Pattern.root field.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
The first Node (which is in Pattern.root) should be an instance of Pattern$BnMS class.
ACTUAL -
An instance of Pattern$StartS class is found instead. Which means the search is not optimized.

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
/* Author: Hong Dai Thanh/nhahtdh */

import java.lang.reflect.Field;
import java.util.regex.Pattern;

class BugRegexBnMS {

    public static void dissect(Pattern pattern) throws Exception {
          
        Field rootField = Pattern.class.getDeclaredField("root");
        rootField.setAccessible(true);
        
        Object rootNode = rootField.get(pattern);
        Object currNode = rootNode;
        
        Class nodeClass = rootField.getType();
        Field nextField = nodeClass.getDeclaredField("next");
        nextField.setAccessible(true);
        
        while (currNode != null) {
            System.out.println(currNode.getClass().getName());
            
            currNode = nextField.get(currNode);
        }
        
        System.out.println();
    }
    
    public static void main(String args[]) throws Exception {
        // Match a fixed string with only BMP code points.
        // The first node is an instance of Pattern$BnM as expected
        dissect(Pattern.compile("\\QNikropoeka*Syn34@ma{re}lgin'Skper?\\E"));
        
        // Match a fixed string with supplementary code points
        // EXPECTED: The first node should be an instance of Pattern$BnMS class
        // ACTUAL: The first node is an instance of Pattern$StartS class, and the next one is an instance of Pattern$SliceS class
        dissect(Pattern.compile("abf\uD83C\uDC04\uD83C\uDC05\uD83C\uDC06\uD83C\uDC04\uD83C\uDC04abfgh\uD83C\uDC06\uD83C\uDC04\uD83C\uDC04\uD83C\uDC04\uD83C\uDC04"));
    }
}
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
The error comes from the check in Pattern$BnM class:

static Node optimize(Node node) {
    if (!(node instanceof Slice)) {
        return node;
    }

Pattern$Slice and Pattern$SliceS are child class of Pattern$SliceNode. This check excludes Pattern$SliceS from being optimized.

The simplest fix is to check whether node is instanceof SliceS also.