JDK14/Java14源码在线阅读

/*
 * Copyright (c) 2016, 2017, 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.
 *
 */

#include "precompiled.hpp"
#include "asm/macroAssembler.hpp"
#include "runtime/sharedRuntime.hpp"
#include "vmreg_x86.inline.hpp"
#ifdef COMPILER1
#include "c1/c1_Runtime1.hpp"
#endif //COMPILER1

#define __ masm->

#ifdef COMPILER1
// ---------------------------------------------------------------------------
// Object.hashCode, System.identityHashCode can pull the hashCode from the
// header word instead of doing a full VM transition once it's been computed.
// Since hashCode is usually polymorphic at call sites we can't do this
// optimization at the call site without a lot of work.
void SharedRuntime::inline_check_hashcode_from_object_header(MacroAssembler* masm,
                                 const methodHandle& method,
                                 Register obj_reg,
                                 Register result) {
  Label slowCase;

  // Unlike for Object.hashCode, System.identityHashCode is static method and
  // gets object as argument instead of the receiver.
  if (method->intrinsic_id() == vmIntrinsics::_identityHashCode) {
    Label Continue;
    // return 0 for null reference input
    __ cmpptr(obj_reg, (int32_t)NULL_WORD);
    __ jcc(Assembler::notEqual, Continue);
    __ xorptr(result, result);
    __ ret(0);
    __ bind(Continue);
  }

  __ movptr(result, Address(obj_reg, oopDesc::mark_offset_in_bytes()));

  // check if locked
  __ testptr(result, markWord::unlocked_value);
  __ jcc(Assembler::zero, slowCase);

  if (UseBiasedLocking) {
    // Check if biased and fall through to runtime if so
    __ testptr(result, markWord::biased_lock_bit_in_place);
    __ jcc(Assembler::notZero, slowCase);
  }

  // get hash
#ifdef _LP64
  // Read the header and build a mask to get its hash field.
  // Depend on hash_mask being at most 32 bits and avoid the use of hash_mask_in_place
  // because it could be larger than 32 bits in a 64-bit vm. See markWord.hpp.

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