1 /*
2 * Copyright (c) 1997, 2020, 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 "code/vtableStubs.hpp"
28 #include "interp_masm_x86.hpp"
29 #include "memory/resourceArea.hpp"
30 #include "oops/compiledICHolder.hpp"
31 #include "oops/instanceKlass.hpp"
32 #include "oops/klassVtable.hpp"
33 #include "runtime/sharedRuntime.hpp"
34 #include "vmreg_x86.inline.hpp"
35 #ifdef COMPILER2
36 #include "opto/runtime.hpp"
37 #endif
38
39 // machine-dependent part of VtableStubs: create VtableStub of correct size and
40 // initialize its code
41
42 #define __ masm->
43
44 #ifndef PRODUCT
45 extern "C" void bad_compiled_vtable_index(JavaThread* thread, oop receiver, int index);
46 #endif
47
48 // These stubs are used by the compiler only.
49 // Argument registers, which must be preserved:
50 // rcx - receiver (always first argument)
51 // rdx - second argument (if any)
52 // Other registers that might be usable:
53 // rax - inline cache register (is interface for itable stub)
54 // rbx - method (used when calling out to interpreter)
55 // Available now, but may become callee-save at some point:
56 // rsi, rdi
57 // Note that rax and rdx are also used for return values.
58
59 VtableStub* VtableStubs::create_vtable_stub(int vtable_index) {
60 // Read "A word on VtableStub sizing" in share/code/vtableStubs.hpp for details on stub sizing.
61 const int stub_code_length = code_size_limit(true);
62 VtableStub* s = new(stub_code_length) VtableStub(true, vtable_index);
63 // Can be NULL if there is no free space in the code cache.
64 if (s == NULL) {
65 return NULL;
66 }
67
68 // Count unused bytes in instruction sequences of variable size.
69 // We add them to the computed buffer size in order to avoid
70 // overflow in subsequently generated stubs.
71 address start_pc;
72 int slop_bytes = 0;
73 int slop_delta = 0;
74 // No variance was detected in vtable stub sizes. Setting index_dependent_slop == 0 will unveil any deviation from this observation.
75 const int index_dependent_slop = 0;
76
77 ResourceMark rm;
78 CodeBuffer cb(s->entry_point(), stub_code_length);
79 MacroAssembler* masm = new MacroAssembler(&cb);
80
81 #if (!defined(PRODUCT) && defined(COMPILER2))
82 if (CountCompiledCalls) {
83 __ incrementl(ExternalAddress((address) SharedRuntime::nof_megamorphic_calls_addr()));
84 }
85 #endif
86
87 // get receiver (need to skip return address on top of stack)
88 assert(VtableStub::receiver_location() == rcx->as_VMReg(), "receiver expected in rcx");
89
90 // get receiver klass
91 address npe_addr = __ pc();
92 __ movptr(rax, Address(rcx, oopDesc::klass_offset_in_bytes()));
93
94 #ifndef PRODUCT
95 if (DebugVtables) {
96 Label L;
97 start_pc = __ pc();
98 // check offset vs vtable length
99 __ cmpl(Address(rax, Klass::vtable_length_offset()), vtable_index*vtableEntry::size());
100 slop_delta = 6 - (__ pc() - start_pc); // cmpl varies in length, depending on data
101 slop_bytes += slop_delta;
102 assert(slop_delta >= 0, "negative slop(%d) encountered, adjust code size estimate!", slop_delta);
103
104 __ jcc(Assembler::greater, L);
105 __ movl(rbx, vtable_index);
106 // VTABLE TODO: find upper bound for call_VM length.
107 start_pc = __ pc();
108 __ call_VM(noreg, CAST_FROM_FN_PTR(address, bad_compiled_vtable_index), rcx, rbx);
109 slop_delta = 500 - (__ pc() - start_pc);
110 slop_bytes += slop_delta;
111 assert(slop_delta >= 0, "negative slop(%d) encountered, adjust code size estimate!", slop_delta);
112 __ bind(L);
113 }
114 #endif // PRODUCT
115
116 const Register method = rbx;
117
118 // load Method* and target address
119 start_pc = __ pc();
120 __ lookup_virtual_method(rax, vtable_index, method);
121 slop_delta = 6 - (int)(__ pc() - start_pc);
122 slop_bytes += slop_delta;
123 assert(slop_delta >= 0, "negative slop(%d) encountered, adjust code size estimate!", slop_delta);
124
125 #ifndef PRODUCT
126 if (DebugVtables) {
127 Label L;
128 __ cmpptr(method, (int32_t)NULL_WORD);
129 __ jcc(Assembler::equal, L);
130 __ cmpptr(Address(method, Method::from_compiled_offset()), (int32_t)NULL_WORD);
131 __ jcc(Assembler::notZero, L);
132 __ stop("Vtable entry is NULL");
133 __ bind(L);
134 }
135 #endif // PRODUCT
136
137 // rax: receiver klass
138 // method (rbx): Method*
139 // rcx: receiver
140 address ame_addr = __ pc();
141 __ jmp( Address(method, Method::from_compiled_offset()));
142
143 masm->flush();
144 slop_bytes += index_dependent_slop; // add'l slop for size variance due to large itable offsets
145 bookkeeping(masm, tty, s, npe_addr, ame_addr, true, vtable_index, slop_bytes, index_dependent_slop);
146
147 return s;
148 }
149
150
151 VtableStub* VtableStubs::create_itable_stub(int itable_index) {
152 // Read "A word on VtableStub sizing" in share/code/vtableStubs.hpp for details on stub sizing.
153 const int stub_code_length = code_size_limit(false);
154 VtableStub* s = new(stub_code_length) VtableStub(false, itable_index);
155 // Can be NULL if there is no free space in the code cache.
156 if (s == NULL) {
157 return NULL;
158 }
159 // Count unused bytes in instruction sequences of variable size.
160 // We add them to the computed buffer size in order to avoid
161 // overflow in subsequently generated stubs.
162 address start_pc;
163 int slop_bytes = 0;
164 int slop_delta = 0;
165 const int index_dependent_slop = (itable_index == 0) ? 4 : // code size change with transition from 8-bit to 32-bit constant (@index == 32).
166 (itable_index < 32) ? 3 : 0; // index == 0 generates even shorter code.
167
168 ResourceMark rm;
169 CodeBuffer cb(s->entry_point(), stub_code_length);
170 MacroAssembler* masm = new MacroAssembler(&cb);
171
172 #if (!defined(PRODUCT) && defined(COMPILER2))
173 if (CountCompiledCalls) {
174 __ incrementl(ExternalAddress((address) SharedRuntime::nof_megamorphic_calls_addr()));
175 }
176 #endif /* PRODUCT */
177
178 // Entry arguments:
179 // rax: CompiledICHolder
180 // rcx: Receiver
181
182 // Most registers are in use; we'll use rax, rbx, rsi, rdi
183 // (If we need to make rsi, rdi callee-save, do a push/pop here.)
184 const Register recv_klass_reg = rsi;
185 const Register holder_klass_reg = rax; // declaring interface klass (DECC)
186 const Register resolved_klass_reg = rbx; // resolved interface klass (REFC)
187 const Register temp_reg = rdi;
188
189 const Register icholder_reg = rax;
190 __ movptr(resolved_klass_reg, Address(icholder_reg, CompiledICHolder::holder_klass_offset()));
191 __ movptr(holder_klass_reg, Address(icholder_reg, CompiledICHolder::holder_metadata_offset()));
192
193 Label L_no_such_interface;
194
195 // get receiver klass (also an implicit null-check)
196 assert(VtableStub::receiver_location() == rcx->as_VMReg(), "receiver expected in rcx");
197 address npe_addr = __ pc();
198 __ load_klass(recv_klass_reg, rcx);
199
200 start_pc = __ pc();
201
202 // Receiver subtype check against REFC.
203 // Destroys recv_klass_reg value.
204 __ lookup_interface_method(// inputs: rec. class, interface
205 recv_klass_reg, resolved_klass_reg, noreg,
206 // outputs: scan temp. reg1, scan temp. reg2
207 recv_klass_reg, temp_reg,
208 L_no_such_interface,
209 /*return_method=*/false);
210
211 const ptrdiff_t typecheckSize = __ pc() - start_pc;
212 start_pc = __ pc();
213
214 // Get selected method from declaring class and itable index
215 const Register method = rbx;
216 __ load_klass(recv_klass_reg, rcx); // restore recv_klass_reg
217 __ lookup_interface_method(// inputs: rec. class, interface, itable index
218 recv_klass_reg, holder_klass_reg, itable_index,
219 // outputs: method, scan temp. reg
220 method, temp_reg,
221 L_no_such_interface);
222
223 const ptrdiff_t lookupSize = __ pc() - start_pc;
224
225 // We expect we need index_dependent_slop extra bytes. Reason:
226 // The emitted code in lookup_interface_method changes when itable_index exceeds 31.
227 // For windows, a narrow estimate was found to be 104. Other OSes not tested.
228 const ptrdiff_t estimate = 104;
229 const ptrdiff_t codesize = typecheckSize + lookupSize + index_dependent_slop;
230 slop_delta = (int)(estimate - codesize);
231 slop_bytes += slop_delta;
232 assert(slop_delta >= 0, "itable #%d: Code size estimate (%d) for lookup_interface_method too small, required: %d", itable_index, (int)estimate, (int)codesize);
233
234 // method (rbx): Method*
235 // rcx: receiver
236
237 #ifdef ASSERT
238 if (DebugVtables) {
239 Label L1;
240 __ cmpptr(method, (int32_t)NULL_WORD);
241 __ jcc(Assembler::equal, L1);
242 __ cmpptr(Address(method, Method::from_compiled_offset()), (int32_t)NULL_WORD);
243 __ jcc(Assembler::notZero, L1);
244 __ stop("Method* is null");
245 __ bind(L1);
246 }
247 #endif // ASSERT
248
249 address ame_addr = __ pc();
250 __ jmp(Address(method, Method::from_compiled_offset()));
251
252 __ bind(L_no_such_interface);
253 // Handle IncompatibleClassChangeError in itable stubs.
254 // More detailed error message.
255 // We force resolving of the call site by jumping to the "handle
256 // wrong method" stub, and so let the interpreter runtime do all the
257 // dirty work.
258 __ jump(RuntimeAddress(SharedRuntime::get_handle_wrong_method_stub()));
259
260 masm->flush();
261 slop_bytes += index_dependent_slop; // add'l slop for size variance due to large itable offsets
262 bookkeeping(masm, tty, s, npe_addr, ame_addr, false, itable_index, slop_bytes, index_dependent_slop);
263
264 return s;
265 }
266
267 int VtableStub::pd_code_alignment() {
268 // x86 cache line size is 64 bytes, but we want to limit alignment loss.
269 const unsigned int icache_line_size = wordSize;
270 return icache_line_size;
271 }