1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/share/vm/prims/jniFastGetField.hpp Wed Apr 27 01:25:04 2016 +0800
1.3 @@ -0,0 +1,102 @@
1.4 +/*
1.5 + * Copyright (c) 2004, 2010, Oracle and/or its affiliates. All rights reserved.
1.6 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.7 + *
1.8 + * This code is free software; you can redistribute it and/or modify it
1.9 + * under the terms of the GNU General Public License version 2 only, as
1.10 + * published by the Free Software Foundation.
1.11 + *
1.12 + * This code is distributed in the hope that it will be useful, but WITHOUT
1.13 + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.14 + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.15 + * version 2 for more details (a copy is included in the LICENSE file that
1.16 + * accompanied this code).
1.17 + *
1.18 + * You should have received a copy of the GNU General Public License version
1.19 + * 2 along with this work; if not, write to the Free Software Foundation,
1.20 + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.21 + *
1.22 + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
1.23 + * or visit www.oracle.com if you need additional information or have any
1.24 + * questions.
1.25 + *
1.26 + */
1.27 +
1.28 +#ifndef SHARE_VM_PRIMS_JNIFASTGETFIELD_HPP
1.29 +#define SHARE_VM_PRIMS_JNIFASTGETFIELD_HPP
1.30 +
1.31 +#include "memory/allocation.hpp"
1.32 +#include "prims/jvm_misc.hpp"
1.33 +
1.34 +// Basic logic of a fast version of jni_Get<Primitive>Field:
1.35 +//
1.36 +// (See safepoint.hpp for a description of _safepoint_counter)
1.37 +//
1.38 +// load _safepoint_counter into old_counter
1.39 +// IF old_counter is odd THEN
1.40 +// a safepoint is going on, return jni_GetXXXField
1.41 +// ELSE
1.42 +// load the primitive field value into result (speculatively)
1.43 +// load _safepoint_counter into new_counter
1.44 +// IF (old_counter == new_counter) THEN
1.45 +// no safepoint happened during the field access, return result
1.46 +// ELSE
1.47 +// a safepoint might have happened in-between, return jni_GetXXXField()
1.48 +// ENDIF
1.49 +// ENDIF
1.50 +//
1.51 +// LoadLoad membars to maintain the load order may be necessary
1.52 +// for some platforms.
1.53 +//
1.54 +// The fast versions don't check for pending suspension request.
1.55 +// This is fine since it's totally read-only and doesn't create new race.
1.56 +//
1.57 +// There is a hypothetical safepoint counter wraparound. But it's not
1.58 +// a practical concern.
1.59 +
1.60 +class JNI_FastGetField : AllStatic {
1.61 + private:
1.62 + enum { LIST_CAPACITY = 40 }; // a conservative number for the number of
1.63 + // speculative loads on all the platforms
1.64 + static address speculative_load_pclist [];
1.65 + static address slowcase_entry_pclist [];
1.66 + static int count;
1.67 +
1.68 + static address generate_fast_get_int_field0(BasicType type);
1.69 + static address generate_fast_get_float_field0(BasicType type);
1.70 +
1.71 + public:
1.72 +#if defined(_WINDOWS) && !defined(_WIN64)
1.73 + static GetBooleanField_t jni_fast_GetBooleanField_fp;
1.74 + static GetByteField_t jni_fast_GetByteField_fp;
1.75 + static GetCharField_t jni_fast_GetCharField_fp;
1.76 + static GetShortField_t jni_fast_GetShortField_fp;
1.77 + static GetIntField_t jni_fast_GetIntField_fp;
1.78 + static GetLongField_t jni_fast_GetLongField_fp;
1.79 + static GetFloatField_t jni_fast_GetFloatField_fp;
1.80 + static GetDoubleField_t jni_fast_GetDoubleField_fp;
1.81 +#endif
1.82 +
1.83 + static address generate_fast_get_boolean_field();
1.84 + static address generate_fast_get_byte_field();
1.85 + static address generate_fast_get_char_field();
1.86 + static address generate_fast_get_short_field();
1.87 + static address generate_fast_get_int_field();
1.88 + static address generate_fast_get_long_field();
1.89 + static address generate_fast_get_float_field();
1.90 + static address generate_fast_get_double_field();
1.91 +
1.92 + // If pc is in speculative_load_pclist, return the corresponding
1.93 + // slow case entry pc. Otherwise, return -1.
1.94 + // This is used by signal/exception handler to handle such case:
1.95 + // After an even safepoint counter is loaded and a fast field access
1.96 + // is about to begin, a GC kicks in and shrinks the heap. Then the
1.97 + // field access may fault. The signal/exception handler needs to
1.98 + // return to the slow case.
1.99 + //
1.100 + // The GC may decide to temporarily stuff some bad values into handles,
1.101 + // for example, for debugging purpose, in which case we need the mapping also.
1.102 + static address find_slowcase_pc(address pc);
1.103 +};
1.104 +
1.105 +#endif // SHARE_VM_PRIMS_JNIFASTGETFIELD_HPP
