aoqi@0: /*
aoqi@0:  * Copyright (c) 2004, 2010, Oracle and/or its affiliates. All rights reserved.
aoqi@0:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
aoqi@0:  *
aoqi@0:  * This code is free software; you can redistribute it and/or modify it
aoqi@0:  * under the terms of the GNU General Public License version 2 only, as
aoqi@0:  * published by the Free Software Foundation.
aoqi@0:  *
aoqi@0:  * This code is distributed in the hope that it will be useful, but WITHOUT
aoqi@0:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
aoqi@0:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
aoqi@0:  * version 2 for more details (a copy is included in the LICENSE file that
aoqi@0:  * accompanied this code).
aoqi@0:  *
aoqi@0:  * You should have received a copy of the GNU General Public License version
aoqi@0:  * 2 along with this work; if not, write to the Free Software Foundation,
aoqi@0:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
aoqi@0:  *
aoqi@0:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
aoqi@0:  * or visit www.oracle.com if you need additional information or have any
aoqi@0:  * questions.
aoqi@0:  *
aoqi@0:  */
aoqi@0: 
aoqi@0: #ifndef SHARE_VM_PRIMS_JNIFASTGETFIELD_HPP
aoqi@0: #define SHARE_VM_PRIMS_JNIFASTGETFIELD_HPP
aoqi@0: 
aoqi@0: #include "memory/allocation.hpp"
aoqi@0: #include "prims/jvm_misc.hpp"
aoqi@0: 
aoqi@0: // Basic logic of a fast version of jni_Get<Primitive>Field:
aoqi@0: //
aoqi@0: // (See safepoint.hpp for a description of _safepoint_counter)
aoqi@0: //
aoqi@0: // load _safepoint_counter into old_counter
aoqi@0: // IF old_counter is odd THEN
aoqi@0: //   a safepoint is going on, return jni_GetXXXField
aoqi@0: // ELSE
aoqi@0: //   load the primitive field value into result (speculatively)
aoqi@0: //   load _safepoint_counter into new_counter
aoqi@0: //   IF (old_counter == new_counter) THEN
aoqi@0: //     no safepoint happened during the field access, return result
aoqi@0: //   ELSE
aoqi@0: //     a safepoint might have happened in-between, return jni_GetXXXField()
aoqi@0: //   ENDIF
aoqi@0: // ENDIF
aoqi@0: //
aoqi@0: // LoadLoad membars to maintain the load order may be necessary
aoqi@0: // for some platforms.
aoqi@0: //
aoqi@0: // The fast versions don't check for pending suspension request.
aoqi@0: // This is fine since it's totally read-only and doesn't create new race.
aoqi@0: //
aoqi@0: // There is a hypothetical safepoint counter wraparound. But it's not
aoqi@0: // a practical concern.
aoqi@0: 
aoqi@0: class JNI_FastGetField : AllStatic {
aoqi@0:  private:
aoqi@0:   enum { LIST_CAPACITY = 40 };      // a conservative number for the number of
aoqi@0:                                     // speculative loads on all the platforms
aoqi@0:   static address speculative_load_pclist [];
aoqi@0:   static address slowcase_entry_pclist   [];
aoqi@0:   static int     count;
aoqi@0: 
aoqi@0:   static address generate_fast_get_int_field0(BasicType type);
aoqi@0:   static address generate_fast_get_float_field0(BasicType type);
aoqi@0: 
aoqi@0:  public:
aoqi@0: #if defined(_WINDOWS) && !defined(_WIN64)
aoqi@0:   static GetBooleanField_t jni_fast_GetBooleanField_fp;
aoqi@0:   static GetByteField_t    jni_fast_GetByteField_fp;
aoqi@0:   static GetCharField_t    jni_fast_GetCharField_fp;
aoqi@0:   static GetShortField_t   jni_fast_GetShortField_fp;
aoqi@0:   static GetIntField_t     jni_fast_GetIntField_fp;
aoqi@0:   static GetLongField_t    jni_fast_GetLongField_fp;
aoqi@0:   static GetFloatField_t   jni_fast_GetFloatField_fp;
aoqi@0:   static GetDoubleField_t  jni_fast_GetDoubleField_fp;
aoqi@0: #endif
aoqi@0: 
aoqi@0:   static address generate_fast_get_boolean_field();
aoqi@0:   static address generate_fast_get_byte_field();
aoqi@0:   static address generate_fast_get_char_field();
aoqi@0:   static address generate_fast_get_short_field();
aoqi@0:   static address generate_fast_get_int_field();
aoqi@0:   static address generate_fast_get_long_field();
aoqi@0:   static address generate_fast_get_float_field();
aoqi@0:   static address generate_fast_get_double_field();
aoqi@0: 
aoqi@0:   // If pc is in speculative_load_pclist, return the corresponding
aoqi@0:   // slow case entry pc. Otherwise, return -1.
aoqi@0:   // This is used by signal/exception handler to handle such case:
aoqi@0:   // After an even safepoint counter is loaded and a fast field access
aoqi@0:   // is about to begin, a GC kicks in and shrinks the heap. Then the
aoqi@0:   // field access may fault. The signal/exception handler needs to
aoqi@0:   // return to the slow case.
aoqi@0:   //
aoqi@0:   // The GC may decide to temporarily stuff some bad values into handles,
aoqi@0:   // for example, for debugging purpose, in which case we need the mapping also.
aoqi@0:   static address find_slowcase_pc(address pc);
aoqi@0: };
aoqi@0: 
aoqi@0: #endif // SHARE_VM_PRIMS_JNIFASTGETFIELD_HPP