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, markWord::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, markWord::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 markWord.hpp.
76   __ shrptr(result, markWord::hash_shift);
77   __ andptr(result, markWord::hash_mask);
78 #else
79   __ andptr(result, markWord::hash_mask_in_place);
80 #endif //_LP64
81 
82   // test if hashCode exists
83   __ jcc(Assembler::zero, slowCase);
84 #ifndef _LP64
85   __ shrptr(result, markWord::hash_shift);
86 #endif
87   __ ret(0);
88   __ bind(slowCase);
89 }
90 #endif //COMPILER1
91