Fri, 03 Dec 2010 15:53:57 -0800
7001379: bootstrap method data needs to be moved from constant pool to a classfile attribute
Reviewed-by: twisti
1 /*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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23 */
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"
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 case JVM_CONSTANT_InvokeDynamicTrans: // fall through
56 add_cp_cache_entry(i);
57 break;
58 }
59 }
61 guarantee((int)_cp_cache_map.length()-1 <= (int)((u2)-1),
62 "all cp cache indexes fit in a u2");
64 _have_invoke_dynamic = ((tag_mask & (1 << JVM_CONSTANT_InvokeDynamic)) != 0);
65 _have_invoke_dynamic |= ((tag_mask & (1 << JVM_CONSTANT_InvokeDynamicTrans)) != 0);
66 }
69 // Creates a constant pool cache given a CPC map
70 // This creates the constant pool cache initially in a state
71 // that is unsafe for concurrent GC processing but sets it to
72 // a safe mode before the constant pool cache is returned.
73 void Rewriter::make_constant_pool_cache(TRAPS) {
74 const int length = _cp_cache_map.length();
75 constantPoolCacheOop cache =
76 oopFactory::new_constantPoolCache(length, methodOopDesc::IsUnsafeConc, CHECK);
77 cache->initialize(_cp_cache_map);
79 // Don't bother with the next pass if there is no JVM_CONSTANT_InvokeDynamic.
80 if (_have_invoke_dynamic) {
81 for (int i = 0; i < length; i++) {
82 int pool_index = cp_cache_entry_pool_index(i);
83 if (pool_index >= 0 &&
84 _pool->tag_at(pool_index).is_invoke_dynamic()) {
85 int bsm_index = _pool->invoke_dynamic_bootstrap_method_ref_index_at(pool_index);
86 if (bsm_index != 0) {
87 assert(_pool->tag_at(bsm_index).is_method_handle(), "must be a MH constant");
88 // There is a CP cache entry holding the BSM for these calls.
89 int bsm_cache_index = cp_entry_to_cp_cache(bsm_index);
90 cache->entry_at(i)->initialize_bootstrap_method_index_in_cache(bsm_cache_index);
91 } else {
92 // There is no CP cache entry holding the BSM for these calls.
93 // We will need to look for a class-global BSM, later.
94 guarantee(AllowTransitionalJSR292, "");
95 }
96 }
97 }
98 }
100 _pool->set_cache(cache);
101 cache->set_constant_pool(_pool());
102 }
106 // The new finalization semantics says that registration of
107 // finalizable objects must be performed on successful return from the
108 // Object.<init> constructor. We could implement this trivially if
109 // <init> were never rewritten but since JVMTI allows this to occur, a
110 // more complicated solution is required. A special return bytecode
111 // is used only by Object.<init> to signal the finalization
112 // registration point. Additionally local 0 must be preserved so it's
113 // available to pass to the registration function. For simplicty we
114 // require that local 0 is never overwritten so it's available as an
115 // argument for registration.
117 void Rewriter::rewrite_Object_init(methodHandle method, TRAPS) {
118 RawBytecodeStream bcs(method);
119 while (!bcs.is_last_bytecode()) {
120 Bytecodes::Code opcode = bcs.raw_next();
121 switch (opcode) {
122 case Bytecodes::_return: *bcs.bcp() = Bytecodes::_return_register_finalizer; break;
124 case Bytecodes::_istore:
125 case Bytecodes::_lstore:
126 case Bytecodes::_fstore:
127 case Bytecodes::_dstore:
128 case Bytecodes::_astore:
129 if (bcs.get_index() != 0) continue;
131 // fall through
132 case Bytecodes::_istore_0:
133 case Bytecodes::_lstore_0:
134 case Bytecodes::_fstore_0:
135 case Bytecodes::_dstore_0:
136 case Bytecodes::_astore_0:
137 THROW_MSG(vmSymbols::java_lang_IncompatibleClassChangeError(),
138 "can't overwrite local 0 in Object.<init>");
139 break;
140 }
141 }
142 }
145 // Rewrite a classfile-order CP index into a native-order CPC index.
146 void Rewriter::rewrite_member_reference(address bcp, int offset) {
147 address p = bcp + offset;
148 int cp_index = Bytes::get_Java_u2(p);
149 int cache_index = cp_entry_to_cp_cache(cp_index);
150 Bytes::put_native_u2(p, cache_index);
151 }
154 void Rewriter::rewrite_invokedynamic(address bcp, int offset) {
155 address p = bcp + offset;
156 assert(p[-1] == Bytecodes::_invokedynamic, "");
157 int cp_index = Bytes::get_Java_u2(p);
158 int cpc = maybe_add_cp_cache_entry(cp_index); // add lazily
159 int cpc2 = add_secondary_cp_cache_entry(cpc);
161 // Replace the trailing four bytes with a CPC index for the dynamic
162 // call site. Unlike other CPC entries, there is one per bytecode,
163 // not just one per distinct CP entry. In other words, the
164 // CPC-to-CP relation is many-to-one for invokedynamic entries.
165 // This means we must use a larger index size than u2 to address
166 // all these entries. That is the main reason invokedynamic
167 // must have a five-byte instruction format. (Of course, other JVM
168 // implementations can use the bytes for other purposes.)
169 Bytes::put_native_u4(p, constantPoolCacheOopDesc::encode_secondary_index(cpc2));
170 // Note: We use native_u4 format exclusively for 4-byte indexes.
171 }
174 // Rewrite some ldc bytecodes to _fast_aldc
175 void Rewriter::maybe_rewrite_ldc(address bcp, int offset, bool is_wide) {
176 assert((*bcp) == (is_wide ? Bytecodes::_ldc_w : Bytecodes::_ldc), "");
177 address p = bcp + offset;
178 int cp_index = is_wide ? Bytes::get_Java_u2(p) : (u1)(*p);
179 constantTag tag = _pool->tag_at(cp_index).value();
180 if (tag.is_method_handle() || tag.is_method_type()) {
181 int cache_index = cp_entry_to_cp_cache(cp_index);
182 if (is_wide) {
183 (*bcp) = Bytecodes::_fast_aldc_w;
184 assert(cache_index == (u2)cache_index, "");
185 Bytes::put_native_u2(p, cache_index);
186 } else {
187 (*bcp) = Bytecodes::_fast_aldc;
188 assert(cache_index == (u1)cache_index, "");
189 (*p) = (u1)cache_index;
190 }
191 }
192 }
195 // Rewrites a method given the index_map information
196 void Rewriter::scan_method(methodOop method) {
198 int nof_jsrs = 0;
199 bool has_monitor_bytecodes = false;
201 {
202 // We cannot tolerate a GC in this block, because we've
203 // cached the bytecodes in 'code_base'. If the methodOop
204 // moves, the bytecodes will also move.
205 No_Safepoint_Verifier nsv;
206 Bytecodes::Code c;
208 // Bytecodes and their length
209 const address code_base = method->code_base();
210 const int code_length = method->code_size();
212 int bc_length;
213 for (int bci = 0; bci < code_length; bci += bc_length) {
214 address bcp = code_base + bci;
215 int prefix_length = 0;
216 c = (Bytecodes::Code)(*bcp);
218 // Since we have the code, see if we can get the length
219 // directly. Some more complicated bytecodes will report
220 // a length of zero, meaning we need to make another method
221 // call to calculate the length.
222 bc_length = Bytecodes::length_for(c);
223 if (bc_length == 0) {
224 bc_length = Bytecodes::length_at(bcp);
226 // length_at will put us at the bytecode after the one modified
227 // by 'wide'. We don't currently examine any of the bytecodes
228 // modified by wide, but in case we do in the future...
229 if (c == Bytecodes::_wide) {
230 prefix_length = 1;
231 c = (Bytecodes::Code)bcp[1];
232 }
233 }
235 assert(bc_length != 0, "impossible bytecode length");
237 switch (c) {
238 case Bytecodes::_lookupswitch : {
239 #ifndef CC_INTERP
240 Bytecode_lookupswitch* bc = Bytecode_lookupswitch_at(bcp);
241 (*bcp) = (
242 bc->number_of_pairs() < BinarySwitchThreshold
243 ? Bytecodes::_fast_linearswitch
244 : Bytecodes::_fast_binaryswitch
245 );
246 #endif
247 break;
248 }
249 case Bytecodes::_getstatic : // fall through
250 case Bytecodes::_putstatic : // fall through
251 case Bytecodes::_getfield : // fall through
252 case Bytecodes::_putfield : // fall through
253 case Bytecodes::_invokevirtual : // fall through
254 case Bytecodes::_invokespecial : // fall through
255 case Bytecodes::_invokestatic :
256 case Bytecodes::_invokeinterface:
257 rewrite_member_reference(bcp, prefix_length+1);
258 break;
259 case Bytecodes::_invokedynamic:
260 rewrite_invokedynamic(bcp, prefix_length+1);
261 break;
262 case Bytecodes::_ldc:
263 maybe_rewrite_ldc(bcp, prefix_length+1, false);
264 break;
265 case Bytecodes::_ldc_w:
266 maybe_rewrite_ldc(bcp, prefix_length+1, true);
267 break;
268 case Bytecodes::_jsr : // fall through
269 case Bytecodes::_jsr_w : nof_jsrs++; break;
270 case Bytecodes::_monitorenter : // fall through
271 case Bytecodes::_monitorexit : has_monitor_bytecodes = true; break;
272 }
273 }
274 }
276 // Update access flags
277 if (has_monitor_bytecodes) {
278 method->set_has_monitor_bytecodes();
279 }
281 // The present of a jsr bytecode implies that the method might potentially
282 // have to be rewritten, so we run the oopMapGenerator on the method
283 if (nof_jsrs > 0) {
284 method->set_has_jsrs();
285 // Second pass will revisit this method.
286 assert(method->has_jsrs(), "");
287 }
288 }
290 // After constant pool is created, revisit methods containing jsrs.
291 methodHandle Rewriter::rewrite_jsrs(methodHandle method, TRAPS) {
292 ResolveOopMapConflicts romc(method);
293 methodHandle original_method = method;
294 method = romc.do_potential_rewrite(CHECK_(methodHandle()));
295 if (method() != original_method()) {
296 // Insert invalid bytecode into original methodOop and set
297 // interpreter entrypoint, so that a executing this method
298 // will manifest itself in an easy recognizable form.
299 address bcp = original_method->bcp_from(0);
300 *bcp = (u1)Bytecodes::_shouldnotreachhere;
301 int kind = Interpreter::method_kind(original_method);
302 original_method->set_interpreter_kind(kind);
303 }
305 // Update monitor matching info.
306 if (romc.monitor_safe()) {
307 method->set_guaranteed_monitor_matching();
308 }
310 return method;
311 }
314 void Rewriter::rewrite(instanceKlassHandle klass, TRAPS) {
315 ResourceMark rm(THREAD);
316 Rewriter rw(klass, klass->constants(), klass->methods(), CHECK);
317 // (That's all, folks.)
318 }
321 void Rewriter::rewrite(instanceKlassHandle klass, constantPoolHandle cpool, objArrayHandle methods, TRAPS) {
322 ResourceMark rm(THREAD);
323 Rewriter rw(klass, cpool, methods, CHECK);
324 // (That's all, folks.)
325 }
328 Rewriter::Rewriter(instanceKlassHandle klass, constantPoolHandle cpool, objArrayHandle methods, TRAPS)
329 : _klass(klass),
330 _pool(cpool),
331 _methods(methods)
332 {
333 assert(_pool->cache() == NULL, "constant pool cache must not be set yet");
335 // determine index maps for methodOop rewriting
336 compute_index_maps();
338 if (RegisterFinalizersAtInit && _klass->name() == vmSymbols::java_lang_Object()) {
339 bool did_rewrite = false;
340 int i = _methods->length();
341 while (i-- > 0) {
342 methodOop method = (methodOop)_methods->obj_at(i);
343 if (method->intrinsic_id() == vmIntrinsics::_Object_init) {
344 // rewrite the return bytecodes of Object.<init> to register the
345 // object for finalization if needed.
346 methodHandle m(THREAD, method);
347 rewrite_Object_init(m, CHECK);
348 did_rewrite = true;
349 break;
350 }
351 }
352 assert(did_rewrite, "must find Object::<init> to rewrite it");
353 }
355 // rewrite methods, in two passes
356 int i, len = _methods->length();
358 for (i = len; --i >= 0; ) {
359 methodOop method = (methodOop)_methods->obj_at(i);
360 scan_method(method);
361 }
363 // allocate constant pool cache, now that we've seen all the bytecodes
364 make_constant_pool_cache(CHECK);
366 for (i = len; --i >= 0; ) {
367 methodHandle m(THREAD, (methodOop)_methods->obj_at(i));
369 if (m->has_jsrs()) {
370 m = rewrite_jsrs(m, CHECK);
371 // Method might have gotten rewritten.
372 _methods->obj_at_put(i, m());
373 }
375 // Set up method entry points for compiler and interpreter.
376 m->link_method(m, CHECK);
378 #ifdef ASSERT
379 if (StressMethodComparator) {
380 static int nmc = 0;
381 for (int j = i; j >= 0 && j >= i-4; j--) {
382 if ((++nmc % 1000) == 0) tty->print_cr("Have run MethodComparator %d times...", nmc);
383 bool z = MethodComparator::methods_EMCP(m(), (methodOop)_methods->obj_at(j));
384 if (j == i && !z) {
385 tty->print("MethodComparator FAIL: "); m->print(); m->print_codes();
386 assert(z, "method must compare equal to itself");
387 }
388 }
389 }
390 #endif //ASSERT
391 }
392 }