1 /*
2 * Copyright (c) 2020, 2024, 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 "opto/c2_MacroAssembler.hpp"
27 #include "opto/c2_CodeStubs.hpp"
28 #include "runtime/objectMonitor.hpp"
29 #include "runtime/sharedRuntime.hpp"
30 #include "runtime/stubRoutines.hpp"
31
32 #define __ masm.
33
34 int C2SafepointPollStub::max_size() const {
35 return 33;
36 }
37
38 void C2SafepointPollStub::emit(C2_MacroAssembler& masm) {
39 assert(SharedRuntime::polling_page_return_handler_blob() != nullptr,
40 "polling page return stub not created yet");
41 address stub = SharedRuntime::polling_page_return_handler_blob()->entry_point();
42
43 RuntimeAddress callback_addr(stub);
44
45 __ bind(entry());
46 InternalAddress safepoint_pc(masm.pc() - masm.offset() + _safepoint_offset);
47 #ifdef _LP64
48 __ lea(rscratch1, safepoint_pc);
49 __ movptr(Address(r15_thread, JavaThread::saved_exception_pc_offset()), rscratch1);
50 #else
51 const Register tmp1 = rcx;
52 const Register tmp2 = rdx;
53 __ push(tmp1);
54 __ push(tmp2);
55
56 __ lea(tmp1, safepoint_pc);
57 __ get_thread(tmp2);
58 __ movptr(Address(tmp2, JavaThread::saved_exception_pc_offset()), tmp1);
59
60 __ pop(tmp2);
61 __ pop(tmp1);
62 #endif
63 __ jump(callback_addr);
64 }
65
66 int C2EntryBarrierStub::max_size() const {
67 return 10;
68 }
69
70 void C2EntryBarrierStub::emit(C2_MacroAssembler& masm) {
71 __ bind(entry());
72 __ call(RuntimeAddress(StubRoutines::method_entry_barrier()));
73 __ jmp(continuation(), false /* maybe_short */);
74 }
75
76 int C2FastUnlockLightweightStub::max_size() const {
77 return 128;
78 }
79
80 void C2FastUnlockLightweightStub::emit(C2_MacroAssembler& masm) {
81 assert(_t == rax, "must be");
82
83 Label restore_held_monitor_count_and_slow_path;
84
85 { // Restore lock-stack and handle the unlock in runtime.
86
87 __ bind(_push_and_slow_path);
88 #ifdef ASSERT
89 // The obj was only cleared in debug.
90 __ movl(_t, Address(_thread, JavaThread::lock_stack_top_offset()));
91 __ movptr(Address(_thread, _t), _obj);
92 #endif
93 __ addl(Address(_thread, JavaThread::lock_stack_top_offset()), oopSize);
94 }
95
96 { // Restore held monitor count and slow path.
97
98 __ bind(restore_held_monitor_count_and_slow_path);
99 // Restore held monitor count.
100 __ increment(Address(_thread, JavaThread::held_monitor_count_offset()));
101 // increment will always result in ZF = 0 (no overflows).
102 __ jmp(slow_path_continuation());
103 }
104
105 { // Handle monitor medium path.
106
107 __ bind(_check_successor);
108
109 Label fix_zf_and_unlocked;
110 const Register monitor = _mark;
111
112 #ifndef _LP64
113 __ jmpb(restore_held_monitor_count_and_slow_path);
114 #else // _LP64
115 // successor null check.
116 __ cmpptr(Address(monitor, OM_OFFSET_NO_MONITOR_VALUE_TAG(succ)), NULL_WORD);
117 __ jccb(Assembler::equal, restore_held_monitor_count_and_slow_path);
118
119 // Release lock.
120 __ movptr(Address(monitor, OM_OFFSET_NO_MONITOR_VALUE_TAG(owner)), NULL_WORD);
121
122 // Fence.
123 // Instead of MFENCE we use a dummy locked add of 0 to the top-of-stack.
124 __ lock(); __ addl(Address(rsp, 0), 0);
125
126 // Recheck successor.
127 __ cmpptr(Address(monitor, OM_OFFSET_NO_MONITOR_VALUE_TAG(succ)), NULL_WORD);
128 // Observed a successor after the release -> fence we have handed off the monitor
129 __ jccb(Assembler::notEqual, fix_zf_and_unlocked);
130
131 // Try to relock, if it fails the monitor has been handed over
132 // TODO: Caveat, this may fail due to deflation, which does
133 // not handle the monitor handoff. Currently only works
134 // due to the responsible thread.
135 __ xorptr(rax, rax);
136 __ lock(); __ cmpxchgptr(_thread, Address(monitor, OM_OFFSET_NO_MONITOR_VALUE_TAG(owner)));
137 __ jccb (Assembler::equal, restore_held_monitor_count_and_slow_path);
138 #endif
139
140 __ bind(fix_zf_and_unlocked);
141 __ xorl(rax, rax);
142 __ jmp(unlocked_continuation());
143 }
144 }
145
146 #undef __