--- a/langtools/src/share/classes/com/sun/tools/javac/comp/Check.java	Mon Feb 13 16:01:43 2012 -0800
+++ b/langtools/src/share/classes/com/sun/tools/javac/comp/Check.java	Tue Feb 14 15:43:52 2012 -0800
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1999, 2011, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1999, 2012, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -2114,25 +2114,26 @@
      */
     void checkOverrideClashes(DiagnosticPosition pos, Type site, MethodSymbol sym) {
          ClashFilter cf = new ClashFilter(site);
-         //for each method m1 that is a member of 'site'...
-         for (Symbol s1 : types.membersClosure(site, false).getElementsByName(sym.name, cf)) {
-            //...find another method m2 that is overridden (directly or indirectly)
-            //by method 'sym' in 'site'
-            for (Symbol s2 : types.membersClosure(site, false).getElementsByName(sym.name, cf)) {
-                if (s1 == s2 || !sym.overrides(s2, site.tsym, types, false)) continue;
+        //for each method m1 that is overridden (directly or indirectly)
+        //by method 'sym' in 'site'...
+        for (Symbol m1 : types.membersClosure(site, false).getElementsByName(sym.name, cf)) {
+            if (!sym.overrides(m1, site.tsym, types, false)) continue;
+             //...check each method m2 that is a member of 'site'
+             for (Symbol m2 : types.membersClosure(site, false).getElementsByName(sym.name, cf)) {
+                if (m2 == m1) continue;
                 //if (i) the signature of 'sym' is not a subsignature of m1 (seen as
                 //a member of 'site') and (ii) m1 has the same erasure as m2, issue an error
-                if (!types.isSubSignature(sym.type, types.memberType(site, s1), false) &&
-                        types.hasSameArgs(s1.erasure(types), s2.erasure(types))) {
+                if (!types.isSubSignature(sym.type, types.memberType(site, m2), false) &&
+                        types.hasSameArgs(m2.erasure(types), m1.erasure(types))) {
                     sym.flags_field |= CLASH;
-                    String key = s2 == sym ?
+                    String key = m1 == sym ?
                             "name.clash.same.erasure.no.override" :
                             "name.clash.same.erasure.no.override.1";
                     log.error(pos,
                             key,
                             sym, sym.location(),
-                            s1, s1.location(),
-                            s2, s2.location());
+                            m2, m2.location(),
+                            m1, m1.location());
                     return;
                 }
             }

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/langtools/test/tools/javac/7142086/T7142086.java	Tue Feb 14 15:43:52 2012 -0800
@@ -0,0 +1,115 @@
+/*
+ * Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test
+ * @bug 7142086
+ * @summary performance problem in Check.checkOverrideClashes(...)
+ * @run main/timeout=10 T7142086
+ */
+
+import com.sun.source.util.JavacTask;
+import java.net.URI;
+import java.util.List;
+import java.util.ArrayList;
+import java.util.Locale;
+import javax.tools.Diagnostic;
+import javax.tools.JavaCompiler;
+import javax.tools.JavaFileObject;
+import javax.tools.SimpleJavaFileObject;
+import javax.tools.StandardJavaFileManager;
+import javax.tools.ToolProvider;
+
+public class T7142086 {
+
+    final static int N_METHODS = 1000;
+
+    static class TestClass extends SimpleJavaFileObject {
+
+        String methTemplate = "abstract void m(A#N p);";
+        String classTemplate = "abstract class Test { #M }";
+
+        String source;
+
+        public TestClass() {
+            super(URI.create("myfo:/Test.java"), JavaFileObject.Kind.SOURCE);
+            StringBuilder buf = new StringBuilder();
+            for (int i = 0 ; i < N_METHODS ; i++) {
+                buf.append(methTemplate.replace("#N", String.valueOf(i)));
+                buf.append("\n");
+            }
+            source = classTemplate.replace("#M", buf.toString());
+        }
+
+        @Override
+        public CharSequence getCharContent(boolean ignoreEncodingErrors) {
+            return source;
+        }
+    }
+
+    static class AnSource extends SimpleJavaFileObject {
+
+        String classTemplate = "abstract class A#N { }";
+
+        String source;
+
+        public AnSource(int n) {
+            super(URI.create("myfo:/Test.java"), JavaFileObject.Kind.SOURCE);
+            source = classTemplate.replace("#N", String.valueOf(n));
+        }
+
+        @Override
+        public CharSequence getCharContent(boolean ignoreEncodingErrors) {
+            return source;
+        }
+    }
+
+    public static void main(String... args) throws Exception {
+        ArrayList<JavaFileObject> sources = new ArrayList<>();
+        for (int i = 0 ; i < N_METHODS ; i++) {
+            sources.add(new AnSource(i));
+        }
+        sources.add(new TestClass());
+        new T7142086().run(sources);
+    }
+
+    void run(List<JavaFileObject> sources) throws Exception {
+        DiagnosticChecker dc = new DiagnosticChecker();
+        JavaCompiler comp = ToolProvider.getSystemJavaCompiler();
+        StandardJavaFileManager fm = comp.getStandardFileManager(null, null, null);
+        JavacTask ct = (JavacTask)comp.getTask(null, fm, dc,
+                null, null, sources);
+        ct.analyze();
+    }
+
+    static class DiagnosticChecker implements javax.tools.DiagnosticListener<JavaFileObject> {
+
+        boolean errorFound;
+
+        public void report(Diagnostic<? extends JavaFileObject> diagnostic) {
+            if (diagnostic.getKind() == Diagnostic.Kind.ERROR) {
+                throw new AssertionError("unexpected diagnostic: " + diagnostic.getMessage(Locale.getDefault()));
+            }
+        }
+    }
+}