1 /*
 2  * Copyright (c) 2018, 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 "code/codeCache.hpp"
27 #include "code/nmethod.hpp"
28 #include "gc/shared/barrierSet.hpp"
29 #include "gc/shared/barrierSetNMethod.hpp"
30 #include "logging/log.hpp"
31 #include "runtime/thread.hpp"
32 #include "utilities/debug.hpp"
33 
34 int BarrierSetNMethod::disarmed_value() const {
35   return *disarmed_value_address();
36 }
37 
38 bool BarrierSetNMethod::supports_entry_barrier(nmethod* nm) {
39   if (nm->method()->is_method_handle_intrinsic()) {
40     return false;
41   }
42 
43   if (!nm->is_native_method() && !nm->is_compiled_by_c2() && !nm->is_compiled_by_c1()) {
44     return false;
45   }
46 
47   return true;
48 }
49 
50 int BarrierSetNMethod::nmethod_stub_entry_barrier(address* return_address_ptr) {
51   address return_address = *return_address_ptr;
52   CodeBlob* cb = CodeCache::find_blob(return_address);
53   assert(cb != NULL, "invariant");
54 
55   nmethod* nm = cb->as_nmethod();
56   BarrierSetNMethod* bs_nm = BarrierSet::barrier_set()->barrier_set_nmethod();
57 
58   if (!bs_nm->is_armed(nm)) {
59     return 0;
60   }
61 
62   assert(!nm->is_osr_method(), "Should not reach here");
63   // Called upon first entry after being armed
64   bool may_enter = bs_nm->nmethod_entry_barrier(nm);
65   if (!may_enter) {
66     log_trace(nmethod, barrier)("Deoptimizing nmethod: " PTR_FORMAT, p2i(nm));
67     bs_nm->deoptimize(nm, return_address_ptr);
68   }
69   return may_enter ? 0 : 1;
70 }
71 
72 bool BarrierSetNMethod::nmethod_osr_entry_barrier(nmethod* nm) {
73   // This check depends on the invariant that all nmethods that are deoptimized / made not entrant
74   // are NOT disarmed.
75   // This invariant is important because a method can be deoptimized after the method have been
76   // resolved / looked up by OSR by another thread. By not deoptimizing them we guarantee that
77   // a deoptimized method will always hit the barrier and come to the same conclusion - deoptimize
78   if (!is_armed(nm)) {
79     return true;
80   }
81 
82   assert(nm->is_osr_method(), "Should not reach here");
83   log_trace(nmethod, barrier)("Running osr nmethod entry barrier: " PTR_FORMAT, p2i(nm));
84   return nmethod_entry_barrier(nm);
85 }