changeset 433:2a2a02876510

anno-stable.patch: first cut at @Stable, for method handle optimization
author jrose
date Wed, 26 Sep 2012 00:10:40 -0700
parents 0a42ce213e8b
children 3e703c2acebc
files anno-stable.patch series
diffstat 2 files changed, 82 insertions(+), 0 deletions(-) [+]
line wrap: on
line diff
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/anno-stable.patch	Wed Sep 26 00:10:40 2012 -0700
@@ -0,0 +1,81 @@
+Summary: @Stable annotation for constant folding of lazily evaluated variables.
+
+diff --git a/src/share/classes/java/lang/invoke/Stable.java b/src/share/classes/java/lang/invoke/Stable.java
+new file mode 100644
+--- /dev/null
++++ b/src/share/classes/java/lang/invoke/Stable.java
+@@ -0,0 +1,74 @@
++/*
++ * 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.  Oracle designates this
++ * particular file as subject to the "Classpath" exception as provided
++ * by Oracle in the LICENSE file that accompanied this code.
++ *
++ * 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.
++ */
++
++package java.lang.invoke;
++
++import java.lang.annotation.*;
++
++/**
++ * Internal marker for some methods in the JSR 292 implementation.
++ * A field may be annotated as stable if all of its component variables
++ * changes value at most once.
++ * A field's value counts as its component value.
++ * If the field is typed as an array, then all the non-null components
++ * of the array, of depth up to the rank of the field's array type,
++ * also count as component values.
++ * By extension, any variable (either array or field) which has annotated
++ * as stable is called a stable variable, and its non-null or non-zero
++ * value is called a stable value.
++ * <p>
++ * Since all fields begin with a default value of null for references
++ * (resp., zero for primitives), it follows that this annotation indicates
++ * that the first non-null (resp., non-zero) value stored in the field
++ * will never be changed.
++ * <p>
++ * If the field is not of an array type, there are no array elements,
++ * then the value indicated as stable is simply the value of the field.
++ * If the dynamic type of the field value is an array but the static type
++ * is not, the components of the array are <em>not</em> regarded as stable.
++ * <p>
++ * If the field is an array type, then both the field value and
++ * all the components of the field value (if the field value is non-null)
++ * are indicated to be stable.
++ * If the field type is an array type with rank {@code N &gt; 1},
++ * then each component of the field value (if the field value is non-null),
++ * is regarded as a stable array of rank {@code N-1}.
++ * <p>
++ * Fields which are declared {@code final} may also be annotated as stable.
++ * Since final fields already behave as stable values, such an annotation
++ * indicates no additional information, unless the type of the field is
++ * an array type.
++ * <p>
++ * It is (currently) undefined what happens if a field annotated as stable
++ * is given a third value.  In practice, if the JVM relies on this annotation
++ * to promote a field reference to a constant, it may be that the Java memory
++ * model would appear to be broken, if such a constant (the second value of the field)
++ * is used as the value of the field even after the field value has changed.
++ */
++/*non-public*/
++@Target(ElementType.FIELD)
++@Retention(RetentionPolicy.RUNTIME)
++@interface Stable {
++}
--- a/series	Sat Sep 22 01:48:39 2012 -0700
+++ b/series	Wed Sep 26 00:10:40 2012 -0700
@@ -6,6 +6,7 @@
 # review pending before push to hotspot-comp:
 
 # non-pushed files are under review or development, or merely experimental:
+anno-stable.patch               #-/meth #+1dde94130b0c #-buildable
 meth-info-7087570.patch         #-/meth #+1dde94130b0c
 meth.patch                      #-/meth #+1dde94130b0c
 meth-7177472.patch              #-/meth #+1dde94130b0c #-buildable