Wed, 09 Jun 2010 18:50:45 -0700
6939203: JSR 292 needs method handle constants
Summary: Add new CP types CONSTANT_MethodHandle, CONSTANT_MethodType; extend 'ldc' bytecode.
Reviewed-by: twisti, never
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25 # include "incls/_precompiled.incl"
26 # include "incls/_rewriter.cpp.incl"
28 // Computes a CPC map (new_index -> original_index) for constant pool entries
29 // that are referred to by the interpreter at runtime via the constant pool cache.
30 // Also computes a CP map (original_index -> new_index).
31 // Marks entries in CP which require additional processing.
32 void Rewriter::compute_index_maps() {
33 const int length = _pool->length();
34 init_cp_map(length);
35 for (int i = 0; i < length; i++) {
36 int tag = _pool->tag_at(i).value();
37 switch (tag) {
38 case JVM_CONSTANT_InterfaceMethodref:
39 case JVM_CONSTANT_Fieldref : // fall through
40 case JVM_CONSTANT_Methodref : // fall through
41 case JVM_CONSTANT_MethodHandle : // fall through
42 case JVM_CONSTANT_MethodType : // fall through
43 add_cp_cache_entry(i);
44 break;
45 }
46 }
48 guarantee((int)_cp_cache_map.length()-1 <= (int)((u2)-1),
49 "all cp cache indexes fit in a u2");
50 }
53 // Creates a constant pool cache given a CPC map
54 // This creates the constant pool cache initially in a state
55 // that is unsafe for concurrent GC processing but sets it to
56 // a safe mode before the constant pool cache is returned.
57 void Rewriter::make_constant_pool_cache(TRAPS) {
58 const int length = _cp_cache_map.length();
59 constantPoolCacheOop cache =
60 oopFactory::new_constantPoolCache(length, methodOopDesc::IsUnsafeConc, CHECK);
61 cache->initialize(_cp_cache_map);
62 _pool->set_cache(cache);
63 cache->set_constant_pool(_pool());
64 }
68 // The new finalization semantics says that registration of
69 // finalizable objects must be performed on successful return from the
70 // Object.<init> constructor. We could implement this trivially if
71 // <init> were never rewritten but since JVMTI allows this to occur, a
72 // more complicated solution is required. A special return bytecode
73 // is used only by Object.<init> to signal the finalization
74 // registration point. Additionally local 0 must be preserved so it's
75 // available to pass to the registration function. For simplicty we
76 // require that local 0 is never overwritten so it's available as an
77 // argument for registration.
79 void Rewriter::rewrite_Object_init(methodHandle method, TRAPS) {
80 RawBytecodeStream bcs(method);
81 while (!bcs.is_last_bytecode()) {
82 Bytecodes::Code opcode = bcs.raw_next();
83 switch (opcode) {
84 case Bytecodes::_return: *bcs.bcp() = Bytecodes::_return_register_finalizer; break;
86 case Bytecodes::_istore:
87 case Bytecodes::_lstore:
88 case Bytecodes::_fstore:
89 case Bytecodes::_dstore:
90 case Bytecodes::_astore:
91 if (bcs.get_index() != 0) continue;
93 // fall through
94 case Bytecodes::_istore_0:
95 case Bytecodes::_lstore_0:
96 case Bytecodes::_fstore_0:
97 case Bytecodes::_dstore_0:
98 case Bytecodes::_astore_0:
99 THROW_MSG(vmSymbols::java_lang_IncompatibleClassChangeError(),
100 "can't overwrite local 0 in Object.<init>");
101 break;
102 }
103 }
104 }
107 // Rewrite a classfile-order CP index into a native-order CPC index.
108 void Rewriter::rewrite_member_reference(address bcp, int offset) {
109 address p = bcp + offset;
110 int cp_index = Bytes::get_Java_u2(p);
111 int cache_index = cp_entry_to_cp_cache(cp_index);
112 Bytes::put_native_u2(p, cache_index);
113 }
116 void Rewriter::rewrite_invokedynamic(address bcp, int offset) {
117 address p = bcp + offset;
118 assert(p[-1] == Bytecodes::_invokedynamic, "");
119 int cp_index = Bytes::get_Java_u2(p);
120 int cpc = maybe_add_cp_cache_entry(cp_index); // add lazily
121 int cpc2 = add_secondary_cp_cache_entry(cpc);
123 // Replace the trailing four bytes with a CPC index for the dynamic
124 // call site. Unlike other CPC entries, there is one per bytecode,
125 // not just one per distinct CP entry. In other words, the
126 // CPC-to-CP relation is many-to-one for invokedynamic entries.
127 // This means we must use a larger index size than u2 to address
128 // all these entries. That is the main reason invokedynamic
129 // must have a five-byte instruction format. (Of course, other JVM
130 // implementations can use the bytes for other purposes.)
131 Bytes::put_native_u4(p, constantPoolCacheOopDesc::encode_secondary_index(cpc2));
132 // Note: We use native_u4 format exclusively for 4-byte indexes.
133 }
136 // Rewrite some ldc bytecodes to _fast_aldc
137 void Rewriter::maybe_rewrite_ldc(address bcp, int offset, bool is_wide) {
138 assert((*bcp) == (is_wide ? Bytecodes::_ldc_w : Bytecodes::_ldc), "");
139 address p = bcp + offset;
140 int cp_index = is_wide ? Bytes::get_Java_u2(p) : (u1)(*p);
141 constantTag tag = _pool->tag_at(cp_index).value();
142 if (tag.is_method_handle() || tag.is_method_type()) {
143 int cache_index = cp_entry_to_cp_cache(cp_index);
144 if (is_wide) {
145 (*bcp) = Bytecodes::_fast_aldc_w;
146 assert(cache_index == (u2)cache_index, "");
147 Bytes::put_native_u2(p, cache_index);
148 } else {
149 (*bcp) = Bytecodes::_fast_aldc;
150 assert(cache_index == (u1)cache_index, "");
151 (*p) = (u1)cache_index;
152 }
153 }
154 }
157 // Rewrites a method given the index_map information
158 void Rewriter::scan_method(methodOop method) {
160 int nof_jsrs = 0;
161 bool has_monitor_bytecodes = false;
163 {
164 // We cannot tolerate a GC in this block, because we've
165 // cached the bytecodes in 'code_base'. If the methodOop
166 // moves, the bytecodes will also move.
167 No_Safepoint_Verifier nsv;
168 Bytecodes::Code c;
170 // Bytecodes and their length
171 const address code_base = method->code_base();
172 const int code_length = method->code_size();
174 int bc_length;
175 for (int bci = 0; bci < code_length; bci += bc_length) {
176 address bcp = code_base + bci;
177 int prefix_length = 0;
178 c = (Bytecodes::Code)(*bcp);
180 // Since we have the code, see if we can get the length
181 // directly. Some more complicated bytecodes will report
182 // a length of zero, meaning we need to make another method
183 // call to calculate the length.
184 bc_length = Bytecodes::length_for(c);
185 if (bc_length == 0) {
186 bc_length = Bytecodes::length_at(bcp);
188 // length_at will put us at the bytecode after the one modified
189 // by 'wide'. We don't currently examine any of the bytecodes
190 // modified by wide, but in case we do in the future...
191 if (c == Bytecodes::_wide) {
192 prefix_length = 1;
193 c = (Bytecodes::Code)bcp[1];
194 }
195 }
197 assert(bc_length != 0, "impossible bytecode length");
199 switch (c) {
200 case Bytecodes::_lookupswitch : {
201 #ifndef CC_INTERP
202 Bytecode_lookupswitch* bc = Bytecode_lookupswitch_at(bcp);
203 (*bcp) = (
204 bc->number_of_pairs() < BinarySwitchThreshold
205 ? Bytecodes::_fast_linearswitch
206 : Bytecodes::_fast_binaryswitch
207 );
208 #endif
209 break;
210 }
211 case Bytecodes::_getstatic : // fall through
212 case Bytecodes::_putstatic : // fall through
213 case Bytecodes::_getfield : // fall through
214 case Bytecodes::_putfield : // fall through
215 case Bytecodes::_invokevirtual : // fall through
216 case Bytecodes::_invokespecial : // fall through
217 case Bytecodes::_invokestatic :
218 case Bytecodes::_invokeinterface:
219 rewrite_member_reference(bcp, prefix_length+1);
220 break;
221 case Bytecodes::_invokedynamic:
222 rewrite_invokedynamic(bcp, prefix_length+1);
223 break;
224 case Bytecodes::_ldc:
225 maybe_rewrite_ldc(bcp, prefix_length+1, false);
226 break;
227 case Bytecodes::_ldc_w:
228 maybe_rewrite_ldc(bcp, prefix_length+1, true);
229 break;
230 case Bytecodes::_jsr : // fall through
231 case Bytecodes::_jsr_w : nof_jsrs++; break;
232 case Bytecodes::_monitorenter : // fall through
233 case Bytecodes::_monitorexit : has_monitor_bytecodes = true; break;
234 }
235 }
236 }
238 // Update access flags
239 if (has_monitor_bytecodes) {
240 method->set_has_monitor_bytecodes();
241 }
243 // The present of a jsr bytecode implies that the method might potentially
244 // have to be rewritten, so we run the oopMapGenerator on the method
245 if (nof_jsrs > 0) {
246 method->set_has_jsrs();
247 // Second pass will revisit this method.
248 assert(method->has_jsrs(), "");
249 }
250 }
252 // After constant pool is created, revisit methods containing jsrs.
253 methodHandle Rewriter::rewrite_jsrs(methodHandle method, TRAPS) {
254 ResolveOopMapConflicts romc(method);
255 methodHandle original_method = method;
256 method = romc.do_potential_rewrite(CHECK_(methodHandle()));
257 if (method() != original_method()) {
258 // Insert invalid bytecode into original methodOop and set
259 // interpreter entrypoint, so that a executing this method
260 // will manifest itself in an easy recognizable form.
261 address bcp = original_method->bcp_from(0);
262 *bcp = (u1)Bytecodes::_shouldnotreachhere;
263 int kind = Interpreter::method_kind(original_method);
264 original_method->set_interpreter_kind(kind);
265 }
267 // Update monitor matching info.
268 if (romc.monitor_safe()) {
269 method->set_guaranteed_monitor_matching();
270 }
272 return method;
273 }
276 void Rewriter::rewrite(instanceKlassHandle klass, TRAPS) {
277 ResourceMark rm(THREAD);
278 Rewriter rw(klass, klass->constants(), klass->methods(), CHECK);
279 // (That's all, folks.)
280 }
283 void Rewriter::rewrite(instanceKlassHandle klass, constantPoolHandle cpool, objArrayHandle methods, TRAPS) {
284 ResourceMark rm(THREAD);
285 Rewriter rw(klass, cpool, methods, CHECK);
286 // (That's all, folks.)
287 }
290 Rewriter::Rewriter(instanceKlassHandle klass, constantPoolHandle cpool, objArrayHandle methods, TRAPS)
291 : _klass(klass),
292 _pool(cpool),
293 _methods(methods)
294 {
295 assert(_pool->cache() == NULL, "constant pool cache must not be set yet");
297 // determine index maps for methodOop rewriting
298 compute_index_maps();
300 if (RegisterFinalizersAtInit && _klass->name() == vmSymbols::java_lang_Object()) {
301 bool did_rewrite = false;
302 int i = _methods->length();
303 while (i-- > 0) {
304 methodOop method = (methodOop)_methods->obj_at(i);
305 if (method->intrinsic_id() == vmIntrinsics::_Object_init) {
306 // rewrite the return bytecodes of Object.<init> to register the
307 // object for finalization if needed.
308 methodHandle m(THREAD, method);
309 rewrite_Object_init(m, CHECK);
310 did_rewrite = true;
311 break;
312 }
313 }
314 assert(did_rewrite, "must find Object::<init> to rewrite it");
315 }
317 // rewrite methods, in two passes
318 int i, len = _methods->length();
320 for (i = len; --i >= 0; ) {
321 methodOop method = (methodOop)_methods->obj_at(i);
322 scan_method(method);
323 }
325 // allocate constant pool cache, now that we've seen all the bytecodes
326 make_constant_pool_cache(CHECK);
328 for (i = len; --i >= 0; ) {
329 methodHandle m(THREAD, (methodOop)_methods->obj_at(i));
331 if (m->has_jsrs()) {
332 m = rewrite_jsrs(m, CHECK);
333 // Method might have gotten rewritten.
334 _methods->obj_at_put(i, m());
335 }
337 // Set up method entry points for compiler and interpreter.
338 m->link_method(m, CHECK);
340 #ifdef ASSERT
341 if (StressMethodComparator) {
342 static int nmc = 0;
343 for (int j = i; j >= 0 && j >= i-4; j--) {
344 if ((++nmc % 1000) == 0) tty->print_cr("Have run MethodComparator %d times...", nmc);
345 bool z = MethodComparator::methods_EMCP(m(), (methodOop)_methods->obj_at(j));
346 if (j == i && !z) {
347 tty->print("MethodComparator FAIL: "); m->print(); m->print_codes();
348 assert(z, "method must compare equal to itself");
349 }
350 }
351 }
352 #endif //ASSERT
353 }
354 }