--- /dev/null 2019-01-28 17:48:08.000000000 +0800 +++ new/src/share/vm/jfr/utilities/jfrBigEndian.hpp 2019-01-28 17:48:08.000000000 +0800 @@ -0,0 +1,136 @@ +/* + * Copyright (c) 2012, 2019, 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_JFR_UTILITIES_JFRBIGENDIAN_HPP +#define SHARE_VM_JFR_UTILITIES_JFRBIGENDIAN_HPP + +#include "memory/allocation.hpp" +#include "utilities/bytes.hpp" +#include "utilities/macros.hpp" + +#ifndef VM_LITTLE_ENDIAN +# define bigendian_16(x) (x) +# define bigendian_32(x) (x) +# define bigendian_64(x) (x) +#else +# define bigendian_16(x) Bytes::swap_u2(x) +# define bigendian_32(x) Bytes::swap_u4(x) +# define bigendian_64(x) Bytes::swap_u8(x) +#endif + +class JfrBigEndian : AllStatic { + private: + template + static T read_bytes(const address location); + template + static T read_unaligned(const address location); + public: + static bool platform_supports_unaligned_reads(void); + static bool is_aligned(const void* location, size_t size); + template + static T read(const void* location); +}; + +inline bool JfrBigEndian::is_aligned(const void* location, size_t size) { + assert(size <= sizeof(u8), "just checking"); + if (size == sizeof(u1)) { + return true; + } + // check address alignment for datum access + return (((uintptr_t)location & (size -1)) == 0); +} + +template <> +inline u1 JfrBigEndian::read_bytes(const address location) { + return (*location & 0xFF); +} + +template <> +inline u2 JfrBigEndian::read_bytes(const address location) { + return Bytes::get_Java_u2(location); +} + +template <> +inline u4 JfrBigEndian::read_bytes(const address location) { + return Bytes::get_Java_u4(location); +} + +template <> +inline u8 JfrBigEndian::read_bytes(const address location) { + return Bytes::get_Java_u8(location); +} + +template +inline T JfrBigEndian::read_unaligned(const address location) { + assert(location != NULL, "just checking"); + switch (sizeof(T)) { + case sizeof(u1) : + return read_bytes(location); + case sizeof(u2): + return read_bytes(location); + case sizeof(u4): + return read_bytes(location); + case sizeof(u8): + return read_bytes(location); + default: + assert(false, "not reach"); + } + return 0; +} + +inline bool JfrBigEndian::platform_supports_unaligned_reads(void) { +#if defined(IA32) || defined(AMD64) + return true; +#elif defined(SPARC) || defined(ARM) || defined(AARCH64) + return false; +#else + #warning "Unconfigured platform" + return false; +#endif +} + +template +inline T JfrBigEndian::read(const void* location) { + assert(location != NULL, "just checking"); + assert(sizeof(T) <= sizeof(u8), "no support for arbitrary sizes"); + if (sizeof(T) == sizeof(u1)) { + return *(T*)location; + } + if (is_aligned(location, sizeof(T)) || platform_supports_unaligned_reads()) { + // fastest case + switch (sizeof(T)) { + case sizeof(u1): + return *(T*)location; + case sizeof(u2): + return bigendian_16(*(T*)(location)); + case sizeof(u4): + return bigendian_32(*(T*)(location)); + case sizeof(u8): + return bigendian_64(*(T*)(location)); + } + } + return read_unaligned((const address)location); +} + +#endif // SHARE_VM_JFR_UTILITIES_JFRBIGENDIAN_HPP