Mercurial > hg > graal-compiler
view src/share/vm/runtime/jfieldIDWorkaround.hpp @ 0:a61af66fc99e jdk7-b24
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author | duke |
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date | Sat, 01 Dec 2007 00:00:00 +0000 |
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children | c18cbe5936b8 |
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/* * Copyright 2003-2005 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, * CA 95054 USA or visit www.sun.com if you need additional information or * have any questions. * */ 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(klassOop k, intptr_t offset); static bool klass_hash_ok(klassOop k, jfieldID id); static void verify_instance_jfieldID(klassOop k, jfieldID id); public: static bool is_valid_jfieldID(klassOop k, jfieldID id); static bool is_instance_jfieldID(klassOop 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(klassOop 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(klassOop 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(instanceKlassHandle 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); } } };