1 /*
2 * Copyright (c) 1998, 2010, 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 "interpreter/bytecodes.hpp"
27 #include "interpreter/interpreter.hpp"
28 #include "interpreter/rewriter.hpp"
29 #include "memory/gcLocker.hpp"
30 #include "memory/oopFactory.hpp"
31 #include "memory/resourceArea.hpp"
32 #include "oops/generateOopMap.hpp"
33 #include "oops/objArrayOop.hpp"
34 #include "oops/oop.inline.hpp"
35 #include "prims/methodComparator.hpp"
36
37 // Computes a CPC map (new_index -> original_index) for constant pool entries
38 // that are referred to by the interpreter at runtime via the constant pool cache.
39 // Also computes a CP map (original_index -> new_index).
40 // Marks entries in CP which require additional processing.
41 void Rewriter::compute_index_maps() {
42 const int length = _pool->length();
43 init_cp_map(length);
44 jint tag_mask = 0;
45 for (int i = 0; i < length; i++) {
46 int tag = _pool->tag_at(i).value();
47 tag_mask |= (1 << tag);
48 switch (tag) {
49 case JVM_CONSTANT_InterfaceMethodref:
50 case JVM_CONSTANT_Fieldref : // fall through
51 case JVM_CONSTANT_Methodref : // fall through
52 case JVM_CONSTANT_MethodHandle : // fall through
53 case JVM_CONSTANT_MethodType : // fall through
54 case JVM_CONSTANT_InvokeDynamic : // fall through
55 add_cp_cache_entry(i);
56 break;
57 }
58 }
59
60 guarantee((int)_cp_cache_map.length()-1 <= (int)((u2)-1),
61 "all cp cache indexes fit in a u2");
62
63 _have_invoke_dynamic = ((tag_mask & (1 << JVM_CONSTANT_InvokeDynamic)) != 0);
64 }
65
66
67 // Creates a constant pool cache given a CPC map
68 // This creates the constant pool cache initially in a state
69 // that is unsafe for concurrent GC processing but sets it to
70 // a safe mode before the constant pool cache is returned.
71 void Rewriter::make_constant_pool_cache(TRAPS) {
72 const int length = _cp_cache_map.length();
73 constantPoolCacheOop cache =
74 oopFactory::new_constantPoolCache(length, methodOopDesc::IsUnsafeConc, CHECK);
75 cache->initialize(_cp_cache_map);
76
77 // Don't bother to the next pass if there is no JVM_CONSTANT_InvokeDynamic.
78 if (_have_invoke_dynamic) {
79 for (int i = 0; i < length; i++) {
80 int pool_index = cp_cache_entry_pool_index(i);
81 if (pool_index >= 0 &&
82 _pool->tag_at(pool_index).is_invoke_dynamic()) {
83 int bsm_index = _pool->invoke_dynamic_bootstrap_method_ref_index_at(pool_index);
84 if (bsm_index != 0) {
85 assert(_pool->tag_at(bsm_index).is_method_handle(), "must be a MH constant");
86 // There is a CP cache entry holding the BSM for these calls.
87 int bsm_cache_index = cp_entry_to_cp_cache(bsm_index);
88 cache->entry_at(i)->initialize_bootstrap_method_index_in_cache(bsm_cache_index);
89 } else {
90 // There is no CP cache entry holding the BSM for these calls.
91 // We will need to look for a class-global BSM, later.
92 guarantee(AllowTransitionalJSR292, "");
93 }
94 }
95 }
96 }
97
98 _pool->set_cache(cache);
99 cache->set_constant_pool(_pool());
100 }
101
102
103
104 // The new finalization semantics says that registration of
105 // finalizable objects must be performed on successful return from the
106 // Object.<init> constructor. We could implement this trivially if
107 // <init> were never rewritten but since JVMTI allows this to occur, a
108 // more complicated solution is required. A special return bytecode
109 // is used only by Object.<init> to signal the finalization
110 // registration point. Additionally local 0 must be preserved so it's
111 // available to pass to the registration function. For simplicty we
112 // require that local 0 is never overwritten so it's available as an
113 // argument for registration.
114
115 void Rewriter::rewrite_Object_init(methodHandle method, TRAPS) {
116 RawBytecodeStream bcs(method);
117 while (!bcs.is_last_bytecode()) {
118 Bytecodes::Code opcode = bcs.raw_next();
119 switch (opcode) {
120 case Bytecodes::_return: *bcs.bcp() = Bytecodes::_return_register_finalizer; break;
121
122 case Bytecodes::_istore:
123 case Bytecodes::_lstore:
124 case Bytecodes::_fstore:
125 case Bytecodes::_dstore:
126 case Bytecodes::_astore:
127 if (bcs.get_index() != 0) continue;
128
129 // fall through
130 case Bytecodes::_istore_0:
131 case Bytecodes::_lstore_0:
132 case Bytecodes::_fstore_0:
133 case Bytecodes::_dstore_0:
134 case Bytecodes::_astore_0:
135 THROW_MSG(vmSymbols::java_lang_IncompatibleClassChangeError(),
136 "can't overwrite local 0 in Object.<init>");
137 break;
138 }
139 }
140 }
141
142
143 // Rewrite a classfile-order CP index into a native-order CPC index.
144 void Rewriter::rewrite_member_reference(address bcp, int offset) {
145 address p = bcp + offset;
146 int cp_index = Bytes::get_Java_u2(p);
147 int cache_index = cp_entry_to_cp_cache(cp_index);
148 Bytes::put_native_u2(p, cache_index);
149 }
150
151
152 void Rewriter::rewrite_invokedynamic(address bcp, int offset) {
153 address p = bcp + offset;
154 assert(p[-1] == Bytecodes::_invokedynamic, "");
155 int cp_index = Bytes::get_Java_u2(p);
156 int cpc = maybe_add_cp_cache_entry(cp_index); // add lazily
157 int cpc2 = add_secondary_cp_cache_entry(cpc);
158
159 // Replace the trailing four bytes with a CPC index for the dynamic
160 // call site. Unlike other CPC entries, there is one per bytecode,
161 // not just one per distinct CP entry. In other words, the
162 // CPC-to-CP relation is many-to-one for invokedynamic entries.
163 // This means we must use a larger index size than u2 to address
164 // all these entries. That is the main reason invokedynamic
165 // must have a five-byte instruction format. (Of course, other JVM
166 // implementations can use the bytes for other purposes.)
167 Bytes::put_native_u4(p, constantPoolCacheOopDesc::encode_secondary_index(cpc2));
168 // Note: We use native_u4 format exclusively for 4-byte indexes.
169 }
170
171
172 // Rewrite some ldc bytecodes to _fast_aldc
173 void Rewriter::maybe_rewrite_ldc(address bcp, int offset, bool is_wide) {
174 assert((*bcp) == (is_wide ? Bytecodes::_ldc_w : Bytecodes::_ldc), "");
175 address p = bcp + offset;
176 int cp_index = is_wide ? Bytes::get_Java_u2(p) : (u1)(*p);
177 constantTag tag = _pool->tag_at(cp_index).value();
178 if (tag.is_method_handle() || tag.is_method_type()) {
179 int cache_index = cp_entry_to_cp_cache(cp_index);
180 if (is_wide) {
181 (*bcp) = Bytecodes::_fast_aldc_w;
182 assert(cache_index == (u2)cache_index, "");
183 Bytes::put_native_u2(p, cache_index);
184 } else {
185 (*bcp) = Bytecodes::_fast_aldc;
186 assert(cache_index == (u1)cache_index, "");
187 (*p) = (u1)cache_index;
188 }
189 }
190 }
191
192
193 // Rewrites a method given the index_map information
194 void Rewriter::scan_method(methodOop method) {
195
196 int nof_jsrs = 0;
197 bool has_monitor_bytecodes = false;
198
199 {
200 // We cannot tolerate a GC in this block, because we've
201 // cached the bytecodes in 'code_base'. If the methodOop
202 // moves, the bytecodes will also move.
203 No_Safepoint_Verifier nsv;
204 Bytecodes::Code c;
205
206 // Bytecodes and their length
207 const address code_base = method->code_base();
208 const int code_length = method->code_size();
209
210 int bc_length;
211 for (int bci = 0; bci < code_length; bci += bc_length) {
212 address bcp = code_base + bci;
213 int prefix_length = 0;
214 c = (Bytecodes::Code)(*bcp);
215
216 // Since we have the code, see if we can get the length
217 // directly. Some more complicated bytecodes will report
218 // a length of zero, meaning we need to make another method
219 // call to calculate the length.
220 bc_length = Bytecodes::length_for(c);
221 if (bc_length == 0) {
222 bc_length = Bytecodes::length_at(bcp);
223
224 // length_at will put us at the bytecode after the one modified
225 // by 'wide'. We don't currently examine any of the bytecodes
226 // modified by wide, but in case we do in the future...
227 if (c == Bytecodes::_wide) {
228 prefix_length = 1;
229 c = (Bytecodes::Code)bcp[1];
230 }
231 }
232
233 assert(bc_length != 0, "impossible bytecode length");
234
235 switch (c) {
236 case Bytecodes::_lookupswitch : {
237 #ifndef CC_INTERP
238 Bytecode_lookupswitch* bc = Bytecode_lookupswitch_at(bcp);
239 (*bcp) = (
240 bc->number_of_pairs() < BinarySwitchThreshold
241 ? Bytecodes::_fast_linearswitch
242 : Bytecodes::_fast_binaryswitch
243 );
244 #endif
245 break;
246 }
247 case Bytecodes::_getstatic : // fall through
248 case Bytecodes::_putstatic : // fall through
249 case Bytecodes::_getfield : // fall through
250 case Bytecodes::_putfield : // fall through
251 case Bytecodes::_invokevirtual : // fall through
252 case Bytecodes::_invokespecial : // fall through
253 case Bytecodes::_invokestatic :
254 case Bytecodes::_invokeinterface:
255 rewrite_member_reference(bcp, prefix_length+1);
256 break;
257 case Bytecodes::_invokedynamic:
258 rewrite_invokedynamic(bcp, prefix_length+1);
259 break;
260 case Bytecodes::_ldc:
261 maybe_rewrite_ldc(bcp, prefix_length+1, false);
262 break;
263 case Bytecodes::_ldc_w:
264 maybe_rewrite_ldc(bcp, prefix_length+1, true);
265 break;
266 case Bytecodes::_jsr : // fall through
267 case Bytecodes::_jsr_w : nof_jsrs++; break;
268 case Bytecodes::_monitorenter : // fall through
269 case Bytecodes::_monitorexit : has_monitor_bytecodes = true; break;
270 }
271 }
272 }
273
274 // Update access flags
275 if (has_monitor_bytecodes) {
276 method->set_has_monitor_bytecodes();
277 }
278
279 // The present of a jsr bytecode implies that the method might potentially
280 // have to be rewritten, so we run the oopMapGenerator on the method
281 if (nof_jsrs > 0) {
282 method->set_has_jsrs();
283 // Second pass will revisit this method.
284 assert(method->has_jsrs(), "");
285 }
286 }
287
288 // After constant pool is created, revisit methods containing jsrs.
289 methodHandle Rewriter::rewrite_jsrs(methodHandle method, TRAPS) {
290 ResolveOopMapConflicts romc(method);
291 methodHandle original_method = method;
292 method = romc.do_potential_rewrite(CHECK_(methodHandle()));
293 if (method() != original_method()) {
294 // Insert invalid bytecode into original methodOop and set
295 // interpreter entrypoint, so that a executing this method
296 // will manifest itself in an easy recognizable form.
297 address bcp = original_method->bcp_from(0);
298 *bcp = (u1)Bytecodes::_shouldnotreachhere;
299 int kind = Interpreter::method_kind(original_method);
300 original_method->set_interpreter_kind(kind);
301 }
302
303 // Update monitor matching info.
304 if (romc.monitor_safe()) {
305 method->set_guaranteed_monitor_matching();
306 }
307
308 return method;
309 }
310
311
312 void Rewriter::rewrite(instanceKlassHandle klass, TRAPS) {
313 ResourceMark rm(THREAD);
314 Rewriter rw(klass, klass->constants(), klass->methods(), CHECK);
315 // (That's all, folks.)
316 }
317
318
319 void Rewriter::rewrite(instanceKlassHandle klass, constantPoolHandle cpool, objArrayHandle methods, TRAPS) {
320 ResourceMark rm(THREAD);
321 Rewriter rw(klass, cpool, methods, CHECK);
322 // (That's all, folks.)
323 }
324
325
326 Rewriter::Rewriter(instanceKlassHandle klass, constantPoolHandle cpool, objArrayHandle methods, TRAPS)
327 : _klass(klass),
328 _pool(cpool),
329 _methods(methods)
330 {
331 assert(_pool->cache() == NULL, "constant pool cache must not be set yet");
332
333 // determine index maps for methodOop rewriting
334 compute_index_maps();
335
336 if (RegisterFinalizersAtInit && _klass->name() == vmSymbols::java_lang_Object()) {
337 bool did_rewrite = false;
338 int i = _methods->length();
339 while (i-- > 0) {
340 methodOop method = (methodOop)_methods->obj_at(i);
341 if (method->intrinsic_id() == vmIntrinsics::_Object_init) {
342 // rewrite the return bytecodes of Object.<init> to register the
343 // object for finalization if needed.
344 methodHandle m(THREAD, method);
345 rewrite_Object_init(m, CHECK);
346 did_rewrite = true;
347 break;
348 }
349 }
350 assert(did_rewrite, "must find Object::<init> to rewrite it");
351 }
352
353 // rewrite methods, in two passes
354 int i, len = _methods->length();
355
356 for (i = len; --i >= 0; ) {
357 methodOop method = (methodOop)_methods->obj_at(i);
358 scan_method(method);
359 }
360
361 // allocate constant pool cache, now that we've seen all the bytecodes
362 make_constant_pool_cache(CHECK);
363
364 for (i = len; --i >= 0; ) {
365 methodHandle m(THREAD, (methodOop)_methods->obj_at(i));
366
367 if (m->has_jsrs()) {
368 m = rewrite_jsrs(m, CHECK);
369 // Method might have gotten rewritten.
370 _methods->obj_at_put(i, m());
371 }
372
373 // Set up method entry points for compiler and interpreter.
374 m->link_method(m, CHECK);
375
376 #ifdef ASSERT
377 if (StressMethodComparator) {
378 static int nmc = 0;
379 for (int j = i; j >= 0 && j >= i-4; j--) {
380 if ((++nmc % 1000) == 0) tty->print_cr("Have run MethodComparator %d times...", nmc);
381 bool z = MethodComparator::methods_EMCP(m(), (methodOop)_methods->obj_at(j));
382 if (j == i && !z) {
383 tty->print("MethodComparator FAIL: "); m->print(); m->print_codes();
384 assert(z, "method must compare equal to itself");
385 }
386 }
387 }
388 #endif //ASSERT
389 }
390 }