Quelle sharedRuntime_x86.cpp Sprache: C

/*
* Copyright (c) 2016, 2021, 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
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* 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, 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);

  // 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.
  __ shrptr(result, markWord::hash_shift);
  __ andptr(result, markWord::hash_mask);
#else
  __ andptr(result, markWord::hash_mask_in_place);
#endif //_LP64

  // test if hashCode exists
  __ jcc(Assembler::zero, slowCase);
#ifndef _LP64
  __ shrptr(result, markWord::hash_shift);
#endif
  __ ret(0);
  __ bind(slowCase);
}
#endif //COMPILER1

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