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