1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/share/vm/prims/jniFastGetField.hpp Sat Dec 01 00:00:00 2007 +0000
1.3 @@ -0,0 +1,94 @@
1.4 +/*
1.5 + * Copyright 2004 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
1.23 + * CA 95054 USA or visit www.sun.com if you need additional information or
1.24 + * have any questions.
1.25 + *
1.26 + */
1.27 +
1.28 +// Basic logic of a fast version of jni_Get<Primitive>Field:
1.29 +//
1.30 +// (See safepoint.hpp for a description of _safepoint_counter)
1.31 +//
1.32 +// load _safepoint_counter into old_counter
1.33 +// IF old_counter is odd THEN
1.34 +// a safepoint is going on, return jni_GetXXXField
1.35 +// ELSE
1.36 +// load the primitive field value into result (speculatively)
1.37 +// load _safepoint_counter into new_counter
1.38 +// IF (old_counter == new_counter) THEN
1.39 +// no safepoint happened during the field access, return result
1.40 +// ELSE
1.41 +// a safepoint might have happened in-between, return jni_GetXXXField()
1.42 +// ENDIF
1.43 +// ENDIF
1.44 +//
1.45 +// LoadLoad membars to maintain the load order may be necessary
1.46 +// for some platforms.
1.47 +//
1.48 +// The fast versions don't check for pending suspension request.
1.49 +// This is fine since it's totally read-only and doesn't create new race.
1.50 +//
1.51 +// There is a hypothetical safepoint counter wraparound. But it's not
1.52 +// a practical concern.
1.53 +
1.54 +class JNI_FastGetField : AllStatic {
1.55 + private:
1.56 + enum { LIST_CAPACITY = 40 }; // a conservative number for the number of
1.57 + // speculative loads on all the platforms
1.58 + static address speculative_load_pclist [];
1.59 + static address slowcase_entry_pclist [];
1.60 + static int count;
1.61 +
1.62 + static address generate_fast_get_int_field0(BasicType type);
1.63 + static address generate_fast_get_float_field0(BasicType type);
1.64 +
1.65 + public:
1.66 +#if defined(_WINDOWS) && !defined(_WIN64)
1.67 + static GetBooleanField_t jni_fast_GetBooleanField_fp;
1.68 + static GetByteField_t jni_fast_GetByteField_fp;
1.69 + static GetCharField_t jni_fast_GetCharField_fp;
1.70 + static GetShortField_t jni_fast_GetShortField_fp;
1.71 + static GetIntField_t jni_fast_GetIntField_fp;
1.72 + static GetLongField_t jni_fast_GetLongField_fp;
1.73 + static GetFloatField_t jni_fast_GetFloatField_fp;
1.74 + static GetDoubleField_t jni_fast_GetDoubleField_fp;
1.75 +#endif
1.76 +
1.77 + static address generate_fast_get_boolean_field();
1.78 + static address generate_fast_get_byte_field();
1.79 + static address generate_fast_get_char_field();
1.80 + static address generate_fast_get_short_field();
1.81 + static address generate_fast_get_int_field();
1.82 + static address generate_fast_get_long_field();
1.83 + static address generate_fast_get_float_field();
1.84 + static address generate_fast_get_double_field();
1.85 +
1.86 + // If pc is in speculative_load_pclist, return the corresponding
1.87 + // slow case entry pc. Otherwise, return -1.
1.88 + // This is used by signal/exception handler to handle such case:
1.89 + // After an even safepoint counter is loaded and a fast field access
1.90 + // is about to begin, a GC kicks in and shrinks the heap. Then the
1.91 + // field access may fault. The signal/exception handler needs to
1.92 + // return to the slow case.
1.93 + //
1.94 + // The GC may decide to temporarily stuff some bad values into handles,
1.95 + // for example, for debugging purpose, in which case we need the mapping also.
1.96 + static address find_slowcase_pc(address pc);
1.97 +};
