--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/runtime/jfieldIDWorkaround.hpp Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,164 @@
+/*
+ * Copyright (c) 2003, 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
+ * 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.
+ *
+ */
+
+#ifndef SHARE_VM_RUNTIME_JFIELDIDWORKAROUND_HPP
+#define SHARE_VM_RUNTIME_JFIELDIDWORKAROUND_HPP
+
+class jfieldIDWorkaround: AllStatic {
+ // This workaround is because JVMTI doesn't have distinct entry points
+ // for methods that use static jfieldIDs and instance jfieldIDs.
+ // The workaround is to steal a low-order bit:
+ // a 1 means the jfieldID is an instance jfieldID,
+ // and the rest of the word is the offset of the field.
+ // a 0 means the jfieldID is a static jfieldID,
+ // and the rest of the word is the JNIid*.
+ //
+ // Another low-order bit is used to mark if an instance field
+ // is accompanied by an indication of which class it applies to.
+ //
+ // Bit-format of a jfieldID (most significant first):
+ // address:30 instance=0:1 checked=0:1
+ // offset:30 instance=1:1 checked=0:1
+ // klass:23 offset:7 instance=1:1 checked=1:1
+ //
+ // If the offset does not fit in 7 bits, or if the fieldID is
+ // not checked, then the checked bit is zero and the rest of
+ // the word (30 bits) contains only the offset.
+ //
+ private:
+ enum {
+ checked_bits = 1,
+ instance_bits = 1,
+ address_bits = BitsPerWord - checked_bits - instance_bits,
+
+ large_offset_bits = address_bits, // unioned with address
+ small_offset_bits = 7,
+ klass_bits = address_bits - small_offset_bits,
+
+ checked_shift = 0,
+ instance_shift = checked_shift + checked_bits,
+ address_shift = instance_shift + instance_bits,
+
+ offset_shift = address_shift, // unioned with address
+ klass_shift = offset_shift + small_offset_bits,
+
+ checked_mask_in_place = right_n_bits(checked_bits) << checked_shift,
+ instance_mask_in_place = right_n_bits(instance_bits) << instance_shift,
+#ifndef _WIN64
+ large_offset_mask = right_n_bits(large_offset_bits),
+ small_offset_mask = right_n_bits(small_offset_bits),
+ klass_mask = right_n_bits(klass_bits)
+#endif
+ };
+
+#ifdef _WIN64
+ // These values are too big for Win64
+ const static uintptr_t large_offset_mask = right_n_bits(large_offset_bits);
+ const static uintptr_t small_offset_mask = right_n_bits(small_offset_bits);
+ const static uintptr_t klass_mask = right_n_bits(klass_bits);
+#endif
+
+ // helper routines:
+ static bool is_checked_jfieldID(jfieldID id) {
+ uintptr_t as_uint = (uintptr_t) id;
+ return ((as_uint & checked_mask_in_place) != 0);
+ }
+ static intptr_t raw_instance_offset(jfieldID id) {
+ uintptr_t result = (uintptr_t) id >> address_shift;
+ if (VerifyJNIFields && is_checked_jfieldID(id)) {
+ result &= small_offset_mask; // cut off the hash bits
+ }
+ return (intptr_t)result;
+ }
+ static intptr_t encode_klass_hash(Klass* k, intptr_t offset);
+ static bool klass_hash_ok(Klass* k, jfieldID id);
+ static void verify_instance_jfieldID(Klass* k, jfieldID id);
+
+ public:
+ static bool is_valid_jfieldID(Klass* k, jfieldID id);
+
+ static bool is_instance_jfieldID(Klass* k, jfieldID id) {
+ uintptr_t as_uint = (uintptr_t) id;
+ return ((as_uint & instance_mask_in_place) != 0);
+ }
+ static bool is_static_jfieldID(jfieldID id) {
+ uintptr_t as_uint = (uintptr_t) id;
+ return ((as_uint & instance_mask_in_place) == 0);
+ }
+
+ static jfieldID to_instance_jfieldID(Klass* k, int offset) {
+ intptr_t as_uint = ((offset & large_offset_mask) << offset_shift) | instance_mask_in_place;
+ if (VerifyJNIFields) {
+ as_uint |= encode_klass_hash(k, offset);
+ }
+ jfieldID result = (jfieldID) as_uint;
+#ifndef ASSERT
+ // always verify in debug mode; switchable in anything else
+ if (VerifyJNIFields)
+#endif // ASSERT
+ {
+ verify_instance_jfieldID(k, result);
+ }
+ assert(raw_instance_offset(result) == (offset & large_offset_mask), "extract right offset");
+ return result;
+ }
+
+ static intptr_t from_instance_jfieldID(Klass* k, jfieldID id) {
+#ifndef ASSERT
+ // always verify in debug mode; switchable in anything else
+ if (VerifyJNIFields)
+#endif // ASSERT
+ {
+ verify_instance_jfieldID(k, id);
+ }
+ return raw_instance_offset(id);
+ }
+
+ static jfieldID to_static_jfieldID(JNIid* id) {
+ assert(id->is_static_field_id(), "from_JNIid, but not static field id");
+ jfieldID result = (jfieldID) id;
+ assert(from_static_jfieldID(result) == id, "must produce the same static id");
+ return result;
+ }
+
+ static JNIid* from_static_jfieldID(jfieldID id) {
+ assert(jfieldIDWorkaround::is_static_jfieldID(id),
+ "to_JNIid, but not static jfieldID");
+ JNIid* result = (JNIid*) id;
+ assert(result->is_static_field_id(), "to_JNIid, but not static field id");
+ return result;
+ }
+
+ static jfieldID to_jfieldID(InstanceKlass* k, int offset, bool is_static) {
+ if (is_static) {
+ JNIid *id = k->jni_id_for(offset);
+ debug_only(id->set_is_static_field_id());
+ return jfieldIDWorkaround::to_static_jfieldID(id);
+ } else {
+ return jfieldIDWorkaround::to_instance_jfieldID(k, offset);
+ }
+ }
+};
+
+#endif // SHARE_VM_RUNTIME_JFIELDIDWORKAROUND_HPP