changeset 15367:1fcefbcdd542

8163878: Remove unnecessary bridge methods, allocations in java.lang.invoke Reviewed-by: mhaupt, shade
author redestad
date Fri, 12 Aug 2016 11:30:23 +0200
parents d8b8b4cdc2fc
children d755483dc031
files src/java.base/share/classes/java/lang/invoke/BoundMethodHandle.java src/java.base/share/classes/java/lang/invoke/DirectMethodHandle.java src/java.base/share/classes/java/lang/invoke/InvokerBytecodeGenerator.java src/java.base/share/classes/java/lang/invoke/LambdaForm.java src/java.base/share/classes/java/lang/invoke/MemberName.java src/java.base/share/classes/java/lang/invoke/MethodHandleImpl.java src/java.base/share/classes/java/lang/invoke/MethodHandles.java src/java.base/share/classes/java/lang/invoke/MethodType.java src/java.base/share/classes/java/lang/invoke/StringConcatFactory.java src/java.base/share/classes/java/lang/invoke/VarForm.java src/java.base/share/classes/sun/invoke/util/VerifyAccess.java
diffstat 11 files changed, 261 insertions(+), 229 deletions(-) [+]
line wrap: on
line diff
--- a/src/java.base/share/classes/java/lang/invoke/BoundMethodHandle.java	Fri Aug 12 14:38:02 2016 +0800
+++ b/src/java.base/share/classes/java/lang/invoke/BoundMethodHandle.java	Fri Aug 12 11:30:23 2016 +0200
@@ -846,7 +846,7 @@
         }
     }
 
-    private static final Lookup LOOKUP = Lookup.IMPL_LOOKUP;
+    static final Lookup LOOKUP = Lookup.IMPL_LOOKUP;
 
     /**
      * All subclasses must provide such a value describing their type signature.
--- a/src/java.base/share/classes/java/lang/invoke/DirectMethodHandle.java	Fri Aug 12 14:38:02 2016 +0800
+++ b/src/java.base/share/classes/java/lang/invoke/DirectMethodHandle.java	Fri Aug 12 11:30:23 2016 +0200
@@ -259,7 +259,7 @@
     }
 
     private static void maybeCompile(LambdaForm lform, MemberName m) {
-        if (VerifyAccess.isSamePackage(m.getDeclaringClass(), MethodHandle.class))
+        if (lform.vmentry == null && VerifyAccess.isSamePackage(m.getDeclaringClass(), MethodHandle.class))
             // Help along bootstrapping...
             lform.compileToBytecode();
     }
@@ -562,25 +562,36 @@
         return lform;
     }
 
+    private static final Wrapper[] ALL_WRAPPERS = Wrapper.values();
+
     private static LambdaForm makePreparedFieldLambdaForm(byte formOp, boolean isVolatile, int ftypeKind) {
         boolean isGetter  = (formOp & 1) == (AF_GETFIELD & 1);
         boolean isStatic  = (formOp >= AF_GETSTATIC);
         boolean needsInit = (formOp >= AF_GETSTATIC_INIT);
         boolean needsCast = (ftypeKind == FT_CHECKED_REF);
-        Wrapper fw = (needsCast ? Wrapper.OBJECT : Wrapper.values()[ftypeKind]);
+        Wrapper fw = (needsCast ? Wrapper.OBJECT : ALL_WRAPPERS[ftypeKind]);
         Class<?> ft = fw.primitiveType();
         assert(ftypeKind(needsCast ? String.class : ft) == ftypeKind);
-        String tname  = fw.primitiveSimpleName();
-        String ctname = Character.toUpperCase(tname.charAt(0)) + tname.substring(1);
-        if (isVolatile)  ctname += "Volatile";
-        String getOrPut = (isGetter ? "get" : "put");
-        String linkerName = (getOrPut + ctname);  // getObject, putIntVolatile, etc.
+
+        // getObject, putIntVolatile, etc.
+        StringBuilder nameBuilder = new StringBuilder();
+        if (isGetter) {
+            nameBuilder.append("get");
+        } else {
+            nameBuilder.append("put");
+        }
+        nameBuilder.append(fw.primitiveSimpleName());
+        nameBuilder.setCharAt(3, Character.toUpperCase(nameBuilder.charAt(3)));
+        if (isVolatile) {
+            nameBuilder.append("Volatile");
+        }
+
         MethodType linkerType;
         if (isGetter)
             linkerType = MethodType.methodType(ft, Object.class, long.class);
         else
             linkerType = MethodType.methodType(void.class, Object.class, long.class, ft);
-        MemberName linker = new MemberName(Unsafe.class, linkerName, linkerType, REF_invokeVirtual);
+        MemberName linker = new MemberName(Unsafe.class, nameBuilder.toString(), linkerType, REF_invokeVirtual);
         try {
             linker = IMPL_NAMES.resolveOrFail(REF_invokeVirtual, linker, null, NoSuchMethodException.class);
         } catch (ReflectiveOperationException ex) {
@@ -635,11 +646,16 @@
         if (needsCast && isGetter)
             names[POST_CAST] = new Name(NF_checkCast, names[DMH_THIS], names[LINKER_CALL]);
         for (Name n : names)  assert(n != null);
-        String fieldOrStatic = (isStatic ? "Static" : "Field");
-        String lambdaName = (linkerName + fieldOrStatic);  // significant only for debugging
-        if (needsCast)  lambdaName += "Cast";
-        if (needsInit)  lambdaName += "Init";
-        return new LambdaForm(lambdaName, ARG_LIMIT, names, RESULT);
+        // add some detail to the lambdaForm debugname,
+        // significant only for debugging
+        if (isStatic) {
+            nameBuilder.append("Static");
+        } else {
+            nameBuilder.append("Field");
+        }
+        if (needsCast)  nameBuilder.append("Cast");
+        if (needsInit)  nameBuilder.append("Init");
+        return new LambdaForm(nameBuilder.toString(), ARG_LIMIT, names, RESULT);
     }
 
     /**
--- a/src/java.base/share/classes/java/lang/invoke/InvokerBytecodeGenerator.java	Fri Aug 12 14:38:02 2016 +0800
+++ b/src/java.base/share/classes/java/lang/invoke/InvokerBytecodeGenerator.java	Fri Aug 12 11:30:23 2016 +0200
@@ -40,8 +40,8 @@
 import java.io.IOException;
 import java.lang.reflect.Modifier;
 import java.util.Arrays;
+import java.util.ArrayList;
 import java.util.HashMap;
-import java.util.Map;
 import java.util.stream.Stream;
 
 import static java.lang.invoke.LambdaForm.*;
@@ -68,6 +68,7 @@
     private static final String LFN_SIG = "L" + LFN + ";";
     private static final String LL_SIG  = "(L" + OBJ + ";)L" + OBJ + ";";
     private static final String LLV_SIG = "(L" + OBJ + ";L" + OBJ + ";)V";
+    private static final String CLASS_PREFIX = LF + "$";
 
     /** Name of its super class*/
     static final String INVOKER_SUPER_NAME = OBJ;
@@ -96,15 +97,15 @@
     /** Main constructor; other constructors delegate to this one. */
     private InvokerBytecodeGenerator(LambdaForm lambdaForm, int localsMapSize,
                                      String className, String invokerName, MethodType invokerType) {
-        if (invokerName.contains(".")) {
-            int p = invokerName.indexOf('.');
+        int p = invokerName.indexOf('.');
+        if (p > -1) {
             className = invokerName.substring(0, p);
-            invokerName = invokerName.substring(p+1);
+            invokerName = invokerName.substring(p + 1);
         }
         if (DUMP_CLASS_FILES) {
             className = makeDumpableClassName(className);
         }
-        this.className  = LF + "$" + className;
+        this.className  = CLASS_PREFIX + className;
         this.sourceFile = "LambdaForm$" + className;
         this.lambdaForm = lambdaForm;
         this.invokerName = invokerName;
@@ -201,38 +202,34 @@
 
     class CpPatch {
         final int index;
-        final String placeholder;
         final Object value;
-        CpPatch(int index, String placeholder, Object value) {
+        CpPatch(int index, Object value) {
             this.index = index;
-            this.placeholder = placeholder;
             this.value = value;
         }
         public String toString() {
-            return "CpPatch/index="+index+",placeholder="+placeholder+",value="+value;
+            return "CpPatch/index="+index+",value="+value;
         }
     }
 
-    Map<Object, CpPatch> cpPatches = new HashMap<>();
+    private final ArrayList<CpPatch> cpPatches = new ArrayList<>();
 
-    int cph = 0;  // for counting constant placeholders
+    private int cph = 0;  // for counting constant placeholders
 
     String constantPlaceholder(Object arg) {
         String cpPlaceholder = "CONSTANT_PLACEHOLDER_" + cph++;
-        if (DUMP_CLASS_FILES) cpPlaceholder += " <<" + debugString(arg) + ">>";  // debugging aid
-        if (cpPatches.containsKey(cpPlaceholder)) {
-            throw new InternalError("observed CP placeholder twice: " + cpPlaceholder);
-        }
+        if (DUMP_CLASS_FILES) cpPlaceholder += " <<" + debugString(arg) + ">>";
+        // TODO check if arg is already in the constant pool
         // insert placeholder in CP and remember the patch
-        int index = cw.newConst((Object) cpPlaceholder);  // TODO check if already in the constant pool
-        cpPatches.put(cpPlaceholder, new CpPatch(index, cpPlaceholder, arg));
+        int index = cw.newConst((Object) cpPlaceholder);
+        cpPatches.add(new CpPatch(index, arg));
         return cpPlaceholder;
     }
 
     Object[] cpPatches(byte[] classFile) {
         int size = getConstantPoolSize(classFile);
         Object[] res = new Object[size];
-        for (CpPatch p : cpPatches.values()) {
+        for (CpPatch p : cpPatches) {
             if (p.index >= size)
                 throw new InternalError("in cpool["+size+"]: "+p+"\n"+Arrays.toString(Arrays.copyOf(classFile, 20)));
             res[p.index] = p.value;
@@ -741,7 +738,7 @@
                     continue;
                 case IDENTITY:
                     assert(name.arguments.length == 1);
-                    emitPushArguments(name);
+                    emitPushArguments(name, 0);
                     continue;
                 case ZERO:
                     assert(name.arguments.length == 0);
@@ -795,7 +792,7 @@
         assert arrayOpcode == Opcodes.AALOAD || arrayOpcode == Opcodes.AASTORE || arrayOpcode == Opcodes.ARRAYLENGTH;
         Class<?> elementType = name.function.methodType().parameterType(0).getComponentType();
         assert elementType != null;
-        emitPushArguments(name);
+        emitPushArguments(name, 0);
         if (arrayOpcode != Opcodes.ARRAYLENGTH && elementType.isPrimitive()) {
             Wrapper w = Wrapper.forPrimitiveType(elementType);
             arrayOpcode = arrayInsnOpcode(arrayTypeCode(w), arrayOpcode);
@@ -824,7 +821,7 @@
         }
 
         // push arguments
-        emitPushArguments(name);
+        emitPushArguments(name, 0);
 
         // invocation
         MethodType type = name.function.methodType();
@@ -923,7 +920,7 @@
         assert(!(member.getDeclaringClass().isInterface() && refKind == REF_invokeVirtual));
 
         // push arguments
-        emitPushArguments(name);
+        emitPushArguments(name, 0);
 
         // invocation
         if (member.isMethod()) {
@@ -1444,13 +1441,10 @@
         }
     }
 
-    private void emitPushArguments(Name args) {
-        emitPushArguments(args, 0);
-    }
-
     private void emitPushArguments(Name args, int start) {
+        MethodType type = args.function.methodType();
         for (int i = start; i < args.arguments.length; i++) {
-            emitPushArgument(args, i);
+            emitPushArgument(type.parameterType(i), args.arguments[i]);
         }
     }
 
--- a/src/java.base/share/classes/java/lang/invoke/LambdaForm.java	Fri Aug 12 14:38:02 2016 +0800
+++ b/src/java.base/share/classes/java/lang/invoke/LambdaForm.java	Fri Aug 12 11:30:23 2016 +0200
@@ -149,9 +149,9 @@
         static final int ARG_TYPE_LIMIT = ARG_TYPES.length;
         static final int TYPE_LIMIT = ALL_TYPES.length;
 
-        private final char btChar;
-        private final Class<?> btClass;
-        private final Wrapper btWrapper;
+        final char btChar;
+        final Class<?> btClass;
+        final Wrapper btWrapper;
 
         private BasicType(char btChar, Class<?> btClass, Wrapper wrapper) {
             this.btChar = btChar;
@@ -1366,10 +1366,11 @@
     }
 
     public static String basicTypeSignature(MethodType type) {
-        char[] sig = new char[type.parameterCount() + 2];
+        int params = type.parameterCount();
+        char[] sig = new char[params + 2];
         int sigp = 0;
-        for (Class<?> pt : type.parameterList()) {
-            sig[sigp++] = basicTypeChar(pt);
+        while (sigp < params) {
+            sig[sigp] = basicTypeChar(type.parameterType(sigp++));
         }
         sig[sigp++] = '_';
         sig[sigp++] = basicTypeChar(type.returnType());
@@ -1407,7 +1408,7 @@
 
     static final class Name {
         final BasicType type;
-        private short index;
+        @Stable short index;
         final NamedFunction function;
         final Object constraint;  // additional type information, if not null
         @Stable final Object[] arguments;
--- a/src/java.base/share/classes/java/lang/invoke/MemberName.java	Fri Aug 12 14:38:02 2016 +0800
+++ b/src/java.base/share/classes/java/lang/invoke/MemberName.java	Fri Aug 12 11:30:23 2016 +0200
@@ -78,7 +78,7 @@
     private int      flags;       // modifier bits; see reflect.Modifier
     //@Injected JVM_Method* vmtarget;
     //@Injected int         vmindex;
-    private Object   resolution;  // if null, this guy is resolved
+    Object   resolution;  // if null, this guy is resolved
 
     /** Return the declaring class of this member.
      *  In the case of a bare name and type, the declaring class will be null.
@@ -826,7 +826,7 @@
         return resolution == null;
     }
 
-    private void initResolved(boolean isResolved) {
+    void initResolved(boolean isResolved) {
         assert(this.resolution == null);  // not initialized yet!
         if (!isResolved)
             this.resolution = this;
--- a/src/java.base/share/classes/java/lang/invoke/MethodHandleImpl.java	Fri Aug 12 14:38:02 2016 +0800
+++ b/src/java.base/share/classes/java/lang/invoke/MethodHandleImpl.java	Fri Aug 12 11:30:23 2016 +0200
@@ -38,10 +38,9 @@
 import sun.invoke.util.ValueConversions;
 import sun.invoke.util.VerifyType;
 import sun.invoke.util.Wrapper;
+import sun.security.action.GetPropertyAction;
 
 import java.lang.reflect.Array;
-import java.security.AccessController;
-import java.security.PrivilegedAction;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.Iterator;
@@ -61,18 +60,9 @@
  */
 /*non-public*/ abstract class MethodHandleImpl {
     // Do not adjust this except for special platforms:
-    private static final int MAX_ARITY;
-    static {
-        final Object[] values = { 255 };
-        AccessController.doPrivileged(new PrivilegedAction<>() {
-            @Override
-            public Void run() {
-                values[0] = Integer.getInteger(MethodHandleImpl.class.getName()+".MAX_ARITY", 255);
-                return null;
-            }
-        });
-        MAX_ARITY = (Integer) values[0];
-    }
+    private static final int MAX_ARITY = Integer.decode(
+                GetPropertyAction.privilegedGetProperty(
+                        MethodHandleImpl.class.getName()+".MAX_ARITY", "255"));
 
     /// Factory methods to create method handles:
 
@@ -652,7 +642,7 @@
         MethodType srcType = targetType                 // (a..., [b...])=>r
                 .dropParameterTypes(collectArgPos, collectArgPos+collectValCount);
         if (!retainOriginalArgs) {                      // (a..., b...)=>r
-            srcType = srcType.insertParameterTypes(collectArgPos, collectorType.parameterList());
+            srcType = srcType.insertParameterTypes(collectArgPos, collectorType.parameterArray());
         }
         // in  arglist: [0: ...keep1 | cpos: collect...  | cpos+cacount: keep2... ]
         // out arglist: [0: ...keep1 | cpos: collectVal? | cpos+cvcount: keep2... ]
@@ -1097,7 +1087,7 @@
         int arity = type.parameterCount();
         if (arity > 1) {
             MethodHandle mh = throwException(type.dropParameterTypes(1, arity));
-            mh = MethodHandles.dropArguments(mh, 1, type.parameterList().subList(1, arity));
+            mh = MethodHandles.dropArguments(mh, 1, Arrays.copyOfRange(type.parameterArray(), 1, arity));
             return mh;
         }
         return makePairwiseConvert(NF_throwException.resolvedHandle(), type, false, true);
--- a/src/java.base/share/classes/java/lang/invoke/MethodHandles.java	Fri Aug 12 14:38:02 2016 +0800
+++ b/src/java.base/share/classes/java/lang/invoke/MethodHandles.java	Fri Aug 12 11:30:23 2016 +0200
@@ -77,7 +77,7 @@
 
     private MethodHandles() { }  // do not instantiate
 
-    private static final MemberName.Factory IMPL_NAMES = MemberName.getFactory();
+    static final MemberName.Factory IMPL_NAMES = MemberName.getFactory();
 
     // See IMPL_LOOKUP below.
 
@@ -3268,12 +3268,11 @@
      */
     public static
     MethodHandle dropArguments(MethodHandle target, int pos, List<Class<?>> valueTypes) {
-        return dropArguments0(target, pos, copyTypes(valueTypes));
+        return dropArguments0(target, pos, copyTypes(valueTypes.toArray()));
     }
 
-    private static List<Class<?>> copyTypes(List<Class<?>> types) {
-        Object[] a = types.toArray();
-        return Arrays.asList(Arrays.copyOf(a, a.length, Class[].class));
+    private static List<Class<?>> copyTypes(Object[] array) {
+        return Arrays.asList(Arrays.copyOf(array, array.length, Class[].class));
     }
 
     private static
@@ -3352,13 +3351,13 @@
      */
     public static
     MethodHandle dropArguments(MethodHandle target, int pos, Class<?>... valueTypes) {
-        return dropArguments(target, pos, Arrays.asList(valueTypes));
+        return dropArguments0(target, pos, copyTypes(valueTypes));
     }
 
     // private version which allows caller some freedom with error handling
     private static MethodHandle dropArgumentsToMatch(MethodHandle target, int skip, List<Class<?>> newTypes, int pos,
                                       boolean nullOnFailure) {
-        newTypes = copyTypes(newTypes);
+        newTypes = copyTypes(newTypes.toArray());
         List<Class<?>> oldTypes = target.type().parameterList();
         int match = oldTypes.size();
         if (skip != 0) {
@@ -3900,10 +3899,14 @@
         int foldVals = rtype == void.class ? 0 : 1;
         int afterInsertPos = foldPos + foldVals;
         boolean ok = (targetType.parameterCount() >= afterInsertPos + foldArgs);
-        if (ok && !(combinerType.parameterList()
-                    .equals(targetType.parameterList().subList(afterInsertPos,
-                                                               afterInsertPos + foldArgs))))
-            ok = false;
+        if (ok) {
+            for (int i = 0; i < foldArgs; i++) {
+                if (combinerType.parameterType(i) != targetType.parameterType(i + afterInsertPos)) {
+                    ok = false;
+                    break;
+                }
+            }
+        }
         if (ok && foldVals != 0 && combinerType.returnType() != targetType.parameterType(foldPos))
             ok = false;
         if (!ok)
--- a/src/java.base/share/classes/java/lang/invoke/MethodType.java	Fri Aug 12 14:38:02 2016 +0800
+++ b/src/java.base/share/classes/java/lang/invoke/MethodType.java	Fri Aug 12 11:30:23 2016 +0200
@@ -539,10 +539,10 @@
             return res;
         } else {
             // insert after (if need be), then before
-            if (pos < parameterList().size() - 1) {
-                res = res.insertParameterTypes(arrayLength, parameterList().subList(pos + 1, parameterList().size()));
+            if (pos < ptypes.length - 1) {
+                res = res.insertParameterTypes(arrayLength, Arrays.copyOfRange(ptypes, pos + 1, ptypes.length));
             }
-            return res.insertParameterTypes(0, parameterList().subList(0, pos));
+            return res.insertParameterTypes(0, Arrays.copyOf(ptypes, pos));
         }
     }
 
--- a/src/java.base/share/classes/java/lang/invoke/StringConcatFactory.java	Fri Aug 12 14:38:02 2016 +0800
+++ b/src/java.base/share/classes/java/lang/invoke/StringConcatFactory.java	Fri Aug 12 11:30:23 2016 +0200
@@ -285,7 +285,7 @@
                         el.add(new RecipeElement(argC++));
                     }
                 } else {
-                    // Not a special characters, this is a constant embedded into
+                    // Not a special character, this is a constant embedded into
                     // the recipe itself.
                     acc.append(c);
                 }
@@ -321,30 +321,32 @@
     private static final class RecipeElement {
         private final Object value;
         private final int argPos;
+        private final char tag;
 
         public RecipeElement(Object cnst) {
             this.value = Objects.requireNonNull(cnst);
             this.argPos = -1;
+            this.tag = TAG_CONST;
         }
 
         public RecipeElement(int arg) {
             this.value = null;
-            assert (arg >= 0);
             this.argPos = arg;
+            this.tag = TAG_ARG;
         }
 
         public Object getValue() {
-            assert (isConst());
+            assert (tag == TAG_CONST);
             return value;
         }
 
         public int getArgPos() {
-            assert (!isConst());
+            assert (tag == TAG_ARG);
             return argPos;
         }
 
-        public boolean isConst() {
-            return argPos == -1;
+        public char getTag() {
+            return tag;
         }
 
         @Override
@@ -354,16 +356,15 @@
 
             RecipeElement that = (RecipeElement) o;
 
-            boolean isConst = isConst();
-            if (isConst != that.isConst()) return false;
-            if (isConst && (!value.equals(that.value))) return false;
-            if (!isConst && (argPos != that.argPos)) return false;
+            if (this.tag != that.tag) return false;
+            if (this.tag == TAG_CONST && (!value.equals(that.value))) return false;
+            if (this.tag == TAG_ARG && (argPos != that.argPos)) return false;
             return true;
         }
 
         @Override
         public int hashCode() {
-            return argPos;
+            return (int)tag;
         }
     }
 
@@ -643,19 +644,20 @@
      * @return argument types the strategy is going to use
      */
     private static MethodType adaptType(MethodType args) {
-        Class<?>[] ptypes = args.parameterArray();
-        boolean changed = false;
-        for (int i = 0; i < ptypes.length; i++) {
-            Class<?> ptype = ptypes[i];
+        Class<?>[] ptypes = null;
+        for (int i = 0; i < args.parameterCount(); i++) {
+            Class<?> ptype = args.parameterType(i);
             if (!ptype.isPrimitive() &&
                     ptype != String.class &&
                     ptype != Object.class) { // truncate to Object
+                if (ptypes == null) {
+                    ptypes = args.parameterArray();
+                }
                 ptypes[i] = Object.class;
-                changed = true;
             }
             // else other primitives or String or Object (unchanged)
         }
-        return changed
+        return (ptypes != null)
                 ? MethodType.methodType(args.returnType(), ptypes)
                 : args;
     }
@@ -874,24 +876,29 @@
 
                 int off = 0;
                 for (RecipeElement el : recipe.getElements()) {
-                    if (el.isConst()) {
-                        // Guaranteed non-null, no null check required.
-                    } else {
-                        // Null-checks are needed only for String arguments, and when a previous stage
-                        // did not do implicit null-checks. If a String is null, we eagerly replace it
-                        // with "null" constant. Note, we omit Objects here, because we don't call
-                        // .length() on them down below.
-                        int ac = el.getArgPos();
-                        Class<?> cl = arr[ac];
-                        if (cl == String.class && !guaranteedNonNull[ac]) {
-                            Label l0 = new Label();
-                            mv.visitIntInsn(ALOAD, off);
-                            mv.visitJumpInsn(IFNONNULL, l0);
-                            mv.visitLdcInsn("null");
-                            mv.visitIntInsn(ASTORE, off);
-                            mv.visitLabel(l0);
-                        }
-                        off += getParameterSize(cl);
+                    switch (el.getTag()) {
+                        case TAG_CONST:
+                            // Guaranteed non-null, no null check required.
+                            break;
+                        case TAG_ARG:
+                            // Null-checks are needed only for String arguments, and when a previous stage
+                            // did not do implicit null-checks. If a String is null, we eagerly replace it
+                            // with "null" constant. Note, we omit Objects here, because we don't call
+                            // .length() on them down below.
+                            int ac = el.getArgPos();
+                            Class<?> cl = arr[ac];
+                            if (cl == String.class && !guaranteedNonNull[ac]) {
+                                Label l0 = new Label();
+                                mv.visitIntInsn(ALOAD, off);
+                                mv.visitJumpInsn(IFNONNULL, l0);
+                                mv.visitLdcInsn("null");
+                                mv.visitIntInsn(ASTORE, off);
+                                mv.visitLabel(l0);
+                            }
+                            off += getParameterSize(cl);
+                            break;
+                        default:
+                            throw new StringConcatException("Unhandled tag: " + el.getTag());
                     }
                 }
             }
@@ -912,30 +919,35 @@
                 mv.visitInsn(ICONST_0);
 
                 for (RecipeElement el : recipe.getElements()) {
-                    if (el.isConst()) {
-                        Object cnst = el.getValue();
-                        len += cnst.toString().length();
-                    } else {
-                        /*
-                            If an argument is String, then we can call .length() on it. Sized/Exact modes have
-                            converted arguments for us. If an argument is primitive, we can provide a guess
-                            for its String representation size.
-                        */
-                        Class<?> cl = arr[el.getArgPos()];
-                        if (cl == String.class) {
-                            mv.visitIntInsn(ALOAD, off);
-                            mv.visitMethodInsn(
-                                    INVOKEVIRTUAL,
-                                    "java/lang/String",
-                                    "length",
-                                    "()I",
-                                    false
-                            );
-                            mv.visitInsn(IADD);
-                        } else if (cl.isPrimitive()) {
-                            len += estimateSize(cl);
-                        }
-                        off += getParameterSize(cl);
+                    switch (el.getTag()) {
+                        case TAG_CONST:
+                            Object cnst = el.getValue();
+                            len += cnst.toString().length();
+                            break;
+                        case TAG_ARG:
+                            /*
+                                If an argument is String, then we can call .length() on it. Sized/Exact modes have
+                                converted arguments for us. If an argument is primitive, we can provide a guess
+                                for its String representation size.
+                            */
+                            Class<?> cl = arr[el.getArgPos()];
+                            if (cl == String.class) {
+                                mv.visitIntInsn(ALOAD, off);
+                                mv.visitMethodInsn(
+                                        INVOKEVIRTUAL,
+                                        "java/lang/String",
+                                        "length",
+                                        "()I",
+                                        false
+                                );
+                                mv.visitInsn(IADD);
+                            } else if (cl.isPrimitive()) {
+                                len += estimateSize(cl);
+                            }
+                            off += getParameterSize(cl);
+                            break;
+                        default:
+                            throw new StringConcatException("Unhandled tag: " + el.getTag());
                     }
                 }
 
@@ -967,15 +979,20 @@
                 int off = 0;
                 for (RecipeElement el : recipe.getElements()) {
                     String desc;
-                    if (el.isConst()) {
-                        Object cnst = el.getValue();
-                        mv.visitLdcInsn(cnst);
-                        desc = getSBAppendDesc(cnst.getClass());
-                    } else {
-                        Class<?> cl = arr[el.getArgPos()];
-                        mv.visitVarInsn(getLoadOpcode(cl), off);
-                        off += getParameterSize(cl);
-                        desc = getSBAppendDesc(cl);
+                    switch (el.getTag()) {
+                        case TAG_CONST:
+                            Object cnst = el.getValue();
+                            mv.visitLdcInsn(cnst);
+                            desc = getSBAppendDesc(cnst.getClass());
+                            break;
+                        case TAG_ARG:
+                            Class<?> cl = arr[el.getArgPos()];
+                            mv.visitVarInsn(getLoadOpcode(cl), off);
+                            off += getParameterSize(cl);
+                            desc = getSBAppendDesc(cl);
+                            break;
+                        default:
+                            throw new StringConcatException("Unhandled tag: " + el.getTag());
                     }
 
                     mv.visitMethodInsn(
@@ -1245,7 +1262,6 @@
                 }
             }
 
-            List<Class<?>> ptypesList = Arrays.asList(ptypes);
             MethodHandle[] lengthers = new MethodHandle[pc];
 
             // Figure out lengths: constants' lengths can be deduced on the spot.
@@ -1253,24 +1269,29 @@
             // call the usual String.length(). Primitive values string sizes can be estimated.
             int initial = 0;
             for (RecipeElement el : recipe.getElements()) {
-                if (el.isConst()) {
-                    Object cnst = el.getValue();
-                    initial += cnst.toString().length();
-                } else {
-                    final int i = el.getArgPos();
-                    Class<?> type = ptypesList.get(i);
-                    if (type.isPrimitive()) {
-                        MethodHandle est = MethodHandles.constant(int.class, estimateSize(type));
-                        est = MethodHandles.dropArguments(est, 0, type);
-                        lengthers[i] = est;
-                    } else {
-                        lengthers[i] = STRING_LENGTH;
-                    }
+                switch (el.getTag()) {
+                    case TAG_CONST:
+                        Object cnst = el.getValue();
+                        initial += cnst.toString().length();
+                        break;
+                    case TAG_ARG:
+                        final int i = el.getArgPos();
+                        Class<?> type = ptypes[i];
+                        if (type.isPrimitive()) {
+                            MethodHandle est = MethodHandles.constant(int.class, estimateSize(type));
+                            est = MethodHandles.dropArguments(est, 0, type);
+                            lengthers[i] = est;
+                        } else {
+                            lengthers[i] = STRING_LENGTH;
+                        }
+                        break;
+                    default:
+                        throw new StringConcatException("Unhandled tag: " + el.getTag());
                 }
             }
 
             // Create (StringBuilder, <args>) shape for appending:
-            MethodHandle builder = MethodHandles.dropArguments(MethodHandles.identity(StringBuilder.class), 1, ptypesList);
+            MethodHandle builder = MethodHandles.dropArguments(MethodHandles.identity(StringBuilder.class), 1, ptypes);
 
             // Compose append calls. This is done in reverse because the application order is
             // reverse as well.
@@ -1278,19 +1299,24 @@
             for (int i = elements.size() - 1; i >= 0; i--) {
                 RecipeElement el = elements.get(i);
                 MethodHandle appender;
-                if (el.isConst()) {
-                    Object constant = el.getValue();
-                    MethodHandle mh = appender(adaptToStringBuilder(constant.getClass()));
-                    appender = MethodHandles.insertArguments(mh, 1, constant);
-                } else {
-                    int ac = el.getArgPos();
-                    appender = appender(ptypesList.get(ac));
+                switch (el.getTag()) {
+                    case TAG_CONST:
+                        Object constant = el.getValue();
+                        MethodHandle mh = appender(adaptToStringBuilder(constant.getClass()));
+                        appender = MethodHandles.insertArguments(mh, 1, constant);
+                        break;
+                    case TAG_ARG:
+                        int ac = el.getArgPos();
+                        appender = appender(ptypes[ac]);
 
-                    // Insert dummy arguments to match the prefix in the signature.
-                    // The actual appender argument will be the ac-ith argument.
-                    if (ac != 0) {
-                        appender = MethodHandles.dropArguments(appender, 1, ptypesList.subList(0, ac));
-                    }
+                        // Insert dummy arguments to match the prefix in the signature.
+                        // The actual appender argument will be the ac-ith argument.
+                        if (ac != 0) {
+                            appender = MethodHandles.dropArguments(appender, 1, Arrays.copyOf(ptypes, ac));
+                        }
+                        break;
+                    default:
+                        throw new StringConcatException("Unhandled tag: " + el.getTag());
                 }
                 builder = MethodHandles.foldArguments(builder, appender);
             }
@@ -1460,7 +1486,6 @@
                     ptypes[i] = filter.type().returnType();
                 }
             }
-            List<Class<?>> ptypesList = Arrays.asList(ptypes);
 
             // Start building the combinator tree. The tree "starts" with (<parameters>)String, and "finishes"
             // with the (int, byte[], byte)String in String helper. The combinators are assembled bottom-up,
@@ -1481,12 +1506,17 @@
             // *ending* index.
             for (RecipeElement el : recipe.getElements()) {
                 MethodHandle prepender;
-                if (el.isConst()) {
-                    Object cnst = el.getValue();
-                    prepender = MethodHandles.insertArguments(prepender(cnst.getClass()), 3, cnst);
-                } else {
-                    int pos = el.getArgPos();
-                    prepender = selectArgument(prepender(ptypesList.get(pos)), 3, ptypesList, pos);
+                switch (el.getTag()) {
+                    case TAG_CONST:
+                        Object cnst = el.getValue();
+                        prepender = MethodHandles.insertArguments(prepender(cnst.getClass()), 3, cnst);
+                        break;
+                    case TAG_ARG:
+                        int pos = el.getArgPos();
+                        prepender = selectArgument(prepender(ptypes[pos]), 3, ptypes, pos);
+                        break;
+                    default:
+                        throw new StringConcatException("Unhandled tag: " + el.getTag());
                 }
 
                 // Remove "old" index from arguments
@@ -1507,7 +1537,7 @@
             }
 
             // Fold in byte[] instantiation at argument 0.
-            MethodHandle combiner = MethodHandles.dropArguments(NEW_ARRAY, 2, ptypesList);
+            MethodHandle combiner = MethodHandles.dropArguments(NEW_ARRAY, 2, ptypes);
             mh = MethodHandles.foldArguments(mh, combiner);
 
             // Start combining length and coder mixers.
@@ -1526,36 +1556,41 @@
             byte initialCoder = INITIAL_CODER;
             int initialLen = 0;    // initial length, in characters
             for (RecipeElement el : recipe.getElements()) {
-                if (el.isConst()) {
-                    Object constant = el.getValue();
-                    String s = constant.toString();
-                    initialCoder = (byte) coderMixer(String.class).invoke(initialCoder, s);
-                    initialLen += s.length();
-                } else {
-                    int ac = el.getArgPos();
+                switch (el.getTag()) {
+                    case TAG_CONST:
+                        Object constant = el.getValue();
+                        String s = constant.toString();
+                        initialCoder = (byte) coderMixer(String.class).invoke(initialCoder, s);
+                        initialLen += s.length();
+                        break;
+                    case TAG_ARG:
+                        int ac = el.getArgPos();
 
-                    Class<?> argClass = ptypesList.get(ac);
-                    MethodHandle lm = selectArgument(lengthMixer(argClass), 1, ptypesList, ac);
-                    lm = MethodHandles.dropArguments(lm, 0, byte.class); // (*)
-                    lm = MethodHandles.dropArguments(lm, 2, byte.class);
+                        Class<?> argClass = ptypes[ac];
+                        MethodHandle lm = selectArgument(lengthMixer(argClass), 1, ptypes, ac);
+                        lm = MethodHandles.dropArguments(lm, 0, byte.class); // (*)
+                        lm = MethodHandles.dropArguments(lm, 2, byte.class);
 
-                    MethodHandle cm = selectArgument(coderMixer(argClass),  1, ptypesList, ac);
-                    cm = MethodHandles.dropArguments(cm, 0, int.class);  // (**)
+                        MethodHandle cm = selectArgument(coderMixer(argClass),  1, ptypes, ac);
+                        cm = MethodHandles.dropArguments(cm, 0, int.class);  // (**)
 
-                    // Read this bottom up:
+                        // Read this bottom up:
 
-                    // 4. Drop old index and coder, producing ("new-index", "new-coder", <args>)
-                    mh = MethodHandles.dropArguments(mh, 2, int.class, byte.class);
+                        // 4. Drop old index and coder, producing ("new-index", "new-coder", <args>)
+                        mh = MethodHandles.dropArguments(mh, 2, int.class, byte.class);
 
-                    // 3. Compute "new-index", producing ("new-index", "new-coder", "old-index", "old-coder", <args>)
-                    //    Length mixer ignores both "new-coder" and "old-coder" due to dropArguments above (*)
-                    mh = MethodHandles.foldArguments(mh, lm);
+                        // 3. Compute "new-index", producing ("new-index", "new-coder", "old-index", "old-coder", <args>)
+                        //    Length mixer ignores both "new-coder" and "old-coder" due to dropArguments above (*)
+                        mh = MethodHandles.foldArguments(mh, lm);
 
-                    // 2. Compute "new-coder", producing ("new-coder", "old-index", "old-coder", <args>)
-                    //    Coder mixer ignores the "old-index" arg due to dropArguments above (**)
-                    mh = MethodHandles.foldArguments(mh, cm);
+                        // 2. Compute "new-coder", producing ("new-coder", "old-index", "old-coder", <args>)
+                        //    Coder mixer ignores the "old-index" arg due to dropArguments above (**)
+                        mh = MethodHandles.foldArguments(mh, cm);
 
-                    // 1. The mh shape here is ("old-index", "old-coder", <args>)
+                        // 1. The mh shape here is ("old-index", "old-coder", <args>)
+                        break;
+                    default:
+                        throw new StringConcatException("Unhandled tag: " + el.getTag());
                 }
             }
 
@@ -1582,14 +1617,14 @@
         }
 
         // Adapts: (...prefix..., parameter[pos])R -> (...prefix..., ...parameters...)R
-        private static MethodHandle selectArgument(MethodHandle mh, int prefix, List<Class<?>> ptypes, int pos) {
+        private static MethodHandle selectArgument(MethodHandle mh, int prefix, Class<?>[] ptypes, int pos) {
             if (pos == 0) {
-                return MethodHandles.dropArguments(mh, prefix + 1, ptypes.subList(1, ptypes.size()));
-            } else if (pos == ptypes.size() - 1) {
-                return MethodHandles.dropArguments(mh, prefix, ptypes.subList(0, ptypes.size() - 1));
+                return MethodHandles.dropArguments(mh, prefix + 1, Arrays.copyOfRange(ptypes, 1, ptypes.length));
+            } else if (pos == ptypes.length - 1) {
+                return MethodHandles.dropArguments(mh, prefix, Arrays.copyOf(ptypes, ptypes.length - 1));
             } else { // 0 < pos < ptypes.size() - 1
-                MethodHandle t = MethodHandles.dropArguments(mh, prefix, ptypes.subList(0, pos));
-                return MethodHandles.dropArguments(t, prefix + 1 + pos, ptypes.subList(pos + 1, ptypes.size()));
+                MethodHandle t = MethodHandles.dropArguments(mh, prefix, Arrays.copyOf(ptypes, pos));
+                return MethodHandles.dropArguments(t, prefix + 1 + pos, Arrays.copyOfRange(ptypes, pos + 1, ptypes.length));
             }
         }
 
@@ -1648,8 +1683,8 @@
         private static final ConcurrentMap<Class<?>, MethodHandle> PREPENDERS;
         private static final ConcurrentMap<Class<?>, MethodHandle> LENGTH_MIXERS;
         private static final ConcurrentMap<Class<?>, MethodHandle> CODER_MIXERS;
-        private static final Class<?> STRING_HELPER;
         private static final byte INITIAL_CODER;
+        static final Class<?> STRING_HELPER;
 
         static {
             try {
@@ -1751,7 +1786,7 @@
 
     /* ------------------------------- Common utilities ------------------------------------ */
 
-    private static MethodHandle lookupStatic(Lookup lookup, Class<?> refc, String name, Class<?> rtype, Class<?>... ptypes) {
+    static MethodHandle lookupStatic(Lookup lookup, Class<?> refc, String name, Class<?> rtype, Class<?>... ptypes) {
         try {
             return lookup.findStatic(refc, name, MethodType.methodType(rtype, ptypes));
         } catch (NoSuchMethodException | IllegalAccessException e) {
@@ -1759,7 +1794,7 @@
         }
     }
 
-    private static MethodHandle lookupVirtual(Lookup lookup, Class<?> refc, String name, Class<?> rtype, Class<?>... ptypes) {
+    static MethodHandle lookupVirtual(Lookup lookup, Class<?> refc, String name, Class<?> rtype, Class<?>... ptypes) {
         try {
             return lookup.findVirtual(refc, name, MethodType.methodType(rtype, ptypes));
         } catch (NoSuchMethodException | IllegalAccessException e) {
@@ -1767,7 +1802,7 @@
         }
     }
 
-    private static MethodHandle lookupConstructor(Lookup lookup, Class<?> refc, Class<?> ptypes) {
+    static MethodHandle lookupConstructor(Lookup lookup, Class<?> refc, Class<?> ptypes) {
         try {
             return lookup.findConstructor(refc, MethodType.methodType(void.class, ptypes));
         } catch (NoSuchMethodException | IllegalAccessException e) {
@@ -1775,7 +1810,7 @@
         }
     }
 
-    private static int estimateSize(Class<?> cl) {
+    static int estimateSize(Class<?> cl) {
         if (cl == Integer.TYPE) {
             return 11; // "-2147483648"
         } else if (cl == Boolean.TYPE) {
@@ -1797,7 +1832,7 @@
         }
     }
 
-    private static Class<?> adaptToStringBuilder(Class<?> c) {
+    static Class<?> adaptToStringBuilder(Class<?> c) {
         if (c.isPrimitive()) {
             if (c == Byte.TYPE || c == Short.TYPE) {
                 return int.class;
--- a/src/java.base/share/classes/java/lang/invoke/VarForm.java	Fri Aug 12 14:38:02 2016 +0800
+++ b/src/java.base/share/classes/java/lang/invoke/VarForm.java	Fri Aug 12 11:30:23 2016 +0200
@@ -31,7 +31,6 @@
 import java.lang.reflect.Method;
 import java.lang.reflect.Modifier;
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.List;
 
 /**
@@ -54,7 +53,8 @@
         List<Class<?>> l = new ArrayList<>();
         if (receiver != null)
             l.add(receiver);
-        l.addAll(Arrays.asList(intermediate));
+        for (Class<?> c : intermediate)
+            l.add(c);
 
         // (Receiver, <Intermediates>)Value
         methodType_table[VarHandle.AccessType.GET.ordinal()] =
--- a/src/java.base/share/classes/sun/invoke/util/VerifyAccess.java	Fri Aug 12 14:38:02 2016 +0800
+++ b/src/java.base/share/classes/sun/invoke/util/VerifyAccess.java	Fri Aug 12 11:30:23 2016 +0200
@@ -28,6 +28,7 @@
 import java.lang.reflect.Modifier;
 import static java.lang.reflect.Modifier.*;
 import java.lang.reflect.Module;
+import java.util.Objects;
 import jdk.internal.reflect.Reflection;
 
 /**
@@ -330,15 +331,7 @@
             return true;
         if (class1.getClassLoader() != class2.getClassLoader())
             return false;
-        String name1 = class1.getName(), name2 = class2.getName();
-        int dot = name1.lastIndexOf('.');
-        if (dot != name2.lastIndexOf('.'))
-            return false;
-        for (int i = 0; i < dot; i++) {
-            if (name1.charAt(i) != name2.charAt(i))
-                return false;
-        }
-        return true;
+        return Objects.equals(class1.getPackageName(), class2.getPackageName());
     }
 
     /** Return the package name for this class.