8185925: StackFrameInfo::walker field can be replaced with bitmap to save footprint

8153682: StackFrameInfo.declaringClass could be removed

Reviewed-by: coleenp, mchung

src/java.base/share/classes/java/lang/StackFrameInfo.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, 2016, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2015, 2017, 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
@@ -32,14 +32,12 @@ import java.lang.StackWalker.StackFrame;
 import java.lang.invoke.MethodType;
 
 class StackFrameInfo implements StackFrame {
+    private final byte RETAIN_CLASS_REF = 0x01;
+
     private final static JavaLangInvokeAccess JLIA =
         SharedSecrets.getJavaLangInvokeAccess();
 
-    // Footprint improvement: MemberName::clazz can replace
-    // StackFrameInfo::declaringClass.
-
-    private final StackWalker walker;
-    private final Class<?> declaringClass;
+    private final byte flags;
     private final Object memberName;
     private final short bci;
     private volatile StackTraceElement ste;
@@ -49,8 +47,7 @@ class StackFrameInfo implements StackFrame {
      * to use
      */
     StackFrameInfo(StackWalker walker) {
-        this.walker = walker;
-        this.declaringClass = null;
+        this.flags = walker.retainClassRef ? RETAIN_CLASS_REF : 0;
         this.bci = -1;
         this.memberName = JLIA.newMemberName();
     }
@@ -58,20 +55,20 @@ class StackFrameInfo implements StackFrame {
     // package-private called by StackStreamFactory to skip
     // the capability check
     Class<?> declaringClass() {
-        return declaringClass;
+        return JLIA.getDeclaringClass(memberName);
     }
 
     // ----- implementation of StackFrame methods
 
     @Override
     public String getClassName() {
-        return declaringClass.getName();
+        return declaringClass().getName();
     }
 
     @Override
     public Class<?> getDeclaringClass() {
-        walker.ensureAccessEnabled(RETAIN_CLASS_REFERENCE);
-        return declaringClass;
+        ensureRetainClassRefEnabled();
+        return declaringClass();
     }
 
     @Override
@@ -81,7 +78,7 @@ class StackFrameInfo implements StackFrame {
 
     @Override
     public MethodType getMethodType() {
-        walker.ensureAccessEnabled(RETAIN_CLASS_REFERENCE);
+        ensureRetainClassRefEnabled();
         return JLIA.getMethodType(memberName);
     }
 
@@ -137,4 +134,10 @@ class StackFrameInfo implements StackFrame {
         }
         return s;
     }
+
+    private void ensureRetainClassRefEnabled() {
+        if ((flags & RETAIN_CLASS_REF) == 0) {
+            throw new UnsupportedOperationException("No access to RETAIN_CLASS_REFERENCE");
+        }
+    }
 }

src/java.base/share/classes/java/lang/StackWalker.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, 2016, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2015, 2017, 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
@@ -296,6 +296,7 @@ public final class StackWalker {
     private final Set<Option> options;
     private final ExtendedOption extendedOption;
     private final int estimateDepth;
+    final boolean retainClassRef; // cached for performance
 
     /**
      * Returns a {@code StackWalker} instance.
@@ -412,6 +413,7 @@ public final class StackWalker {
         this.options = options;
         this.estimateDepth = estimateDepth;
         this.extendedOption = extendedOption;
+        this.retainClassRef = hasOption(Option.RETAIN_CLASS_REFERENCE);
     }
 
     private static void checkPermission(Set<Option> options) {
@@ -590,7 +592,7 @@ public final class StackWalker {
      */
     @CallerSensitive
     public Class<?> getCallerClass() {
-        if (!options.contains(Option.RETAIN_CLASS_REFERENCE)) {
+        if (!retainClassRef) {
             throw new UnsupportedOperationException("This stack walker " +
                     "does not have RETAIN_CLASS_REFERENCE access");
         }
@@ -617,11 +619,4 @@ public final class StackWalker {
     boolean hasLocalsOperandsOption() {
         return extendedOption == ExtendedOption.LOCALS_AND_OPERANDS;
     }
-
-    void ensureAccessEnabled(Option access) {
-        if (!hasOption(access)) {
-            throw new UnsupportedOperationException("No access to " + access +
-                    ": " + options.toString());
-        }
-    }
 }

src/java.base/share/classes/java/lang/invoke/MethodHandleImpl.java

@@ -1784,6 +1784,11 @@ import static jdk.internal.org.objectweb.asm.Opcodes.*;
                 MemberName memberName = (MemberName)mname;
                 return memberName.getName();
             }
+            @Override
+            public Class<?> getDeclaringClass(Object mname) {
+                MemberName memberName = (MemberName)mname;
+                return memberName.getDeclaringClass();
+            }
 
             @Override
             public MethodType getMethodType(Object mname) {