Mercurial > hg > truffle
diff 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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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/share/vm/runtime/jfieldIDWorkaround.hpp Sat Dec 01 00:00:00 2007 +0000 @@ -0,0 +1,159 @@ +/* + * 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); + } + } +};