| /* |
| * Copyright (c) 2004, 2010, 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_PRIMS_JNIFASTGETFIELD_HPP |
| #define SHARE_VM_PRIMS_JNIFASTGETFIELD_HPP |
| |
| #include "memory/allocation.hpp" |
| #include "prims/jvm_misc.hpp" |
| |
| // Basic logic of a fast version of jni_Get<Primitive>Field: |
| // |
| // (See safepoint.hpp for a description of _safepoint_counter) |
| // |
| // load _safepoint_counter into old_counter |
| // IF old_counter is odd THEN |
| // a safepoint is going on, return jni_GetXXXField |
| // ELSE |
| // load the primitive field value into result (speculatively) |
| // load _safepoint_counter into new_counter |
| // IF (old_counter == new_counter) THEN |
| // no safepoint happened during the field access, return result |
| // ELSE |
| // a safepoint might have happened in-between, return jni_GetXXXField() |
| // ENDIF |
| // ENDIF |
| // |
| // LoadLoad membars to maintain the load order may be necessary |
| // for some platforms. |
| // |
| // The fast versions don't check for pending suspension request. |
| // This is fine since it's totally read-only and doesn't create new race. |
| // |
| // There is a hypothetical safepoint counter wraparound. But it's not |
| // a practical concern. |
| |
| class JNI_FastGetField : AllStatic { |
| private: |
| enum { LIST_CAPACITY = 40 }; // a conservative number for the number of |
| // speculative loads on all the platforms |
| static address speculative_load_pclist []; |
| static address slowcase_entry_pclist []; |
| static int count; |
| |
| static address generate_fast_get_int_field0(BasicType type); |
| static address generate_fast_get_float_field0(BasicType type); |
| |
| public: |
| #if defined(_WINDOWS) && !defined(_WIN64) |
| static GetBooleanField_t jni_fast_GetBooleanField_fp; |
| static GetByteField_t jni_fast_GetByteField_fp; |
| static GetCharField_t jni_fast_GetCharField_fp; |
| static GetShortField_t jni_fast_GetShortField_fp; |
| static GetIntField_t jni_fast_GetIntField_fp; |
| static GetLongField_t jni_fast_GetLongField_fp; |
| static GetFloatField_t jni_fast_GetFloatField_fp; |
| static GetDoubleField_t jni_fast_GetDoubleField_fp; |
| #endif |
| |
| static address generate_fast_get_boolean_field(); |
| static address generate_fast_get_byte_field(); |
| static address generate_fast_get_char_field(); |
| static address generate_fast_get_short_field(); |
| static address generate_fast_get_int_field(); |
| static address generate_fast_get_long_field(); |
| static address generate_fast_get_float_field(); |
| static address generate_fast_get_double_field(); |
| |
| // If pc is in speculative_load_pclist, return the corresponding |
| // slow case entry pc. Otherwise, return -1. |
| // This is used by signal/exception handler to handle such case: |
| // After an even safepoint counter is loaded and a fast field access |
| // is about to begin, a GC kicks in and shrinks the heap. Then the |
| // field access may fault. The signal/exception handler needs to |
| // return to the slow case. |
| // |
| // The GC may decide to temporarily stuff some bad values into handles, |
| // for example, for debugging purpose, in which case we need the mapping also. |
| static address find_slowcase_pc(address pc); |
| }; |
| |
| #endif // SHARE_VM_PRIMS_JNIFASTGETFIELD_HPP |