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122 lines
4.3 KiB
C++
122 lines
4.3 KiB
C++
/*
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* Copyright (c) 2017, 2023, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*
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*/
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#ifndef SHARE_OOPS_COMPRESSEDOOPS_INLINE_HPP
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#define SHARE_OOPS_COMPRESSEDOOPS_INLINE_HPP
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#include "oops/compressedOops.hpp"
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#include "memory/universe.hpp"
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#include "oops/oop.hpp"
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#include "utilities/align.hpp"
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#include "utilities/globalDefinitions.hpp"
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// Functions for encoding and decoding compressed oops.
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// If the oops are compressed, the type passed to these overloaded functions
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// is narrowOop. All functions are overloaded so they can be called by
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// template functions without conditionals (the compiler instantiates via
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// the right type and inlines the appropriate code).
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// Algorithm for encoding and decoding oops from 64 bit pointers to 32 bit
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// offset from the heap base. Saving the check for null can save instructions
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// in inner GC loops so these are separated.
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inline oop CompressedOops::decode_raw_not_null(narrowOop v) {
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assert(!is_null(v), "narrow oop value can never be zero");
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return decode_raw(v);
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}
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inline oop CompressedOops::decode_raw(narrowOop v) {
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return cast_to_oop((uintptr_t)base() + ((uintptr_t)v << shift()));
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}
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inline oop CompressedOops::decode_not_null(narrowOop v) {
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assert(!is_null(v), "narrow oop value can never be zero");
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oop result = decode_raw(v);
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assert(is_object_aligned(result), "address not aligned: " PTR_FORMAT, p2i(result));
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assert(Universe::is_in_heap(result), "object not in heap " PTR_FORMAT, p2i(result));
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return result;
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}
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inline oop CompressedOops::decode(narrowOop v) {
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return is_null(v) ? nullptr : decode_not_null(v);
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}
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inline narrowOop CompressedOops::encode_not_null(oop v) {
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assert(!is_null(v), "oop value can never be zero");
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assert(is_object_aligned(v), "address not aligned: " PTR_FORMAT, p2i(v));
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assert(is_in(v), "address not in heap range: " PTR_FORMAT, p2i(v));
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uint64_t pd = (uint64_t)(pointer_delta((void*)v, (void*)base(), 1));
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assert(OopEncodingHeapMax > pd, "change encoding max if new encoding");
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narrowOop result = narrow_oop_cast(pd >> shift());
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assert(decode_raw(result) == v, "reversibility");
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return result;
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}
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inline narrowOop CompressedOops::encode(oop v) {
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return is_null(v) ? narrowOop::null : encode_not_null(v);
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}
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inline oop CompressedOops::decode_raw_not_null(oop v) {
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assert(v != nullptr, "object is null");
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return v;
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}
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inline oop CompressedOops::decode_not_null(oop v) {
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assert(Universe::is_in_heap(v), "object not in heap " PTR_FORMAT, p2i(v));
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return v;
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}
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inline oop CompressedOops::decode(oop v) {
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assert(Universe::is_in_heap_or_null(v), "object not in heap " PTR_FORMAT, p2i(v));
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return v;
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}
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inline narrowOop CompressedOops::encode_not_null(narrowOop v) {
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return v;
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}
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inline narrowOop CompressedOops::encode(narrowOop v) {
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return v;
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}
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inline uint32_t CompressedOops::narrow_oop_value(oop o) {
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return narrow_oop_value(encode(o));
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}
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inline uint32_t CompressedOops::narrow_oop_value(narrowOop o) {
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return static_cast<uint32_t>(o);
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}
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template<typename T>
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inline narrowOop CompressedOops::narrow_oop_cast(T i) {
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static_assert(std::is_integral<T>::value, "precondition");
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uint32_t narrow_value = static_cast<uint32_t>(i);
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// Ensure no bits lost in conversion to uint32_t.
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assert(i == static_cast<T>(narrow_value), "narrowOop overflow");
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return static_cast<narrowOop>(narrow_value);
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}
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#endif // SHARE_OOPS_COMPRESSEDOOPS_INLINE_HPP
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