1 /*
   2  * Copyright (c) 2016, 2017, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "asm/macroAssembler.hpp"
  27 #include "runtime/sharedRuntime.hpp"
  28 #include "vmreg_x86.inline.hpp"
  29 #ifdef COMPILER1
  30 #include "c1/c1_Runtime1.hpp"
  31 #endif //COMPILER1
  32 
  33 #define __ masm->
  34 
  35 #ifdef COMPILER1
  36 // ---------------------------------------------------------------------------
  37 // Object.hashCode, System.identityHashCode can pull the hashCode from the
  38 // header word instead of doing a full VM transition once it's been computed.
  39 // Since hashCode is usually polymorphic at call sites we can't do this
  40 // optimization at the call site without a lot of work.
  41 void SharedRuntime::inline_check_hashcode_from_object_header(MacroAssembler* masm,
  42                                  const methodHandle& method,
  43                                  Register obj_reg,
  44                                  Register result) {
  45   Label slowCase;
  46 
  47   // Unlike for Object.hashCode, System.identityHashCode is static method and
  48   // gets object as argument instead of the receiver.
  49   if (method->intrinsic_id() == vmIntrinsics::_identityHashCode) {
  50     Label Continue;
  51     // return 0 for null reference input
  52     __ cmpptr(obj_reg, (int32_t)NULL_WORD);
  53     __ jcc(Assembler::notEqual, Continue);
  54     __ xorptr(result, result);
  55     __ ret(0);
  56     __ bind(Continue);
  57   }
  58 
  59   __ movptr(result, Address(obj_reg, oopDesc::mark_offset_in_bytes()));
  60 
  61   // check if locked
  62   __ testptr(result, markOopDesc::unlocked_value);
  63   __ jcc(Assembler::zero, slowCase);
  64 
  65   if (UseBiasedLocking) {
  66     // Check if biased and fall through to runtime if so
  67     __ testptr(result, markOopDesc::biased_lock_bit_in_place);
  68     __ jcc(Assembler::notZero, slowCase);
  69   }
  70 
  71   // get hash
  72 #ifdef _LP64
  73   // Read the header and build a mask to get its hash field.
  74   // Depend on hash_mask being at most 32 bits and avoid the use of hash_mask_in_place
  75   // because it could be larger than 32 bits in a 64-bit vm. See markOop.hpp.
  76   __ shrptr(result, markOopDesc::hash_shift);
  77   __ andptr(result, markOopDesc::hash_mask);
  78 #else
  79   __ andptr(result, markOopDesc::hash_mask_in_place);
  80 #endif //_LP64
  81 
  82   // test if hashCode exists
  83   __ jcc(Assembler::zero, slowCase);
  84 #ifndef _LP64
  85   __ shrptr(result, markOopDesc::hash_shift);
  86 #endif
  87   __ ret(0);
  88   __ bind(slowCase);
  89 }
  90 #endif //COMPILER1
  91