Mercurial > hg > graal-compiler
view src/share/vm/prims/jniFastGetField.hpp @ 3405:8cbcd406c42e
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
Summary: Do a one-step look-ahead, when sweeping free or garbage blocks, to avoid overstepping sweep limit, which may become a non-block-boundary because of a heap expansion delta coalescing with a previously co-terminal free block.
Reviewed-by: brutisso, tonyp
author | ysr |
---|---|
date | Fri, 27 May 2011 15:05:33 -0700 |
parents | f95d63e2154a |
children |
line wrap: on
line source
/* * 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