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 /*

  * Copyright (c) 1998, 2013, Oracle and/or its affiliates. All rights reserved.

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

  *

  * This code is free software; you can redistribute it and/or modify it

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

  * version 2 for more details (a copy is included in the LICENSE file that

  * accompanied this code).

  *

  * You should have received a copy of the GNU General Public License version

  * 2 along with this work; if not, write to the Free Software Foundation,

  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

  *

  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

  * or visit www.oracle.com if you need additional information or have any

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  */

 #include "precompiled.hpp"

 #include "interpreter/bytecodes.hpp"

 #include "interpreter/interpreter.hpp"

 #include "interpreter/rewriter.hpp"

 #include "memory/gcLocker.hpp"

 #include "memory/resourceArea.hpp"

 #include "oops/generateOopMap.hpp"

 #include "prims/methodHandles.hpp"

 // Computes a CPC map (new_index -> original_index) for constant pool entries

 // that are referred to by the interpreter at runtime via the constant pool cache.

 // Also computes a CP map (original_index -> new_index).

 // Marks entries in CP which require additional processing.

 void Rewriter::compute_index_maps() {

   const int length  = _pool->length();

   init_maps(length);

   bool saw_mh_symbol = false;

   for (int i = 0; i < length; i++) {

     int tag = _pool->tag_at(i).value();

     switch (tag) {

       case JVM_CONSTANT_InterfaceMethodref:

       case JVM_CONSTANT_Fieldref          : // fall through

       case JVM_CONSTANT_Methodref         : // fall through

         add_cp_cache_entry(i);

         break;

       case JVM_CONSTANT_String:

       case JVM_CONSTANT_MethodHandle      : // fall through

       case JVM_CONSTANT_MethodType        : // fall through

         add_resolved_references_entry(i);

         break;

       case JVM_CONSTANT_Utf8:

         if (_pool->symbol_at(i) == vmSymbols::java_lang_invoke_MethodHandle())

           saw_mh_symbol = true;

         break;

     }

   }

   // Record limits of resolved reference map for constant pool cache indices

   record_map_limits();

   guarantee((int)_cp_cache_map.length()-1 <= (int)((u2)-1),

             "all cp cache indexes fit in a u2");

   if (saw_mh_symbol)

     _method_handle_invokers.initialize(length, (int)0);

 }

 // Unrewrite the bytecodes if an error occurs.

 void Rewriter::restore_bytecodes() {

   int len = _methods->length();

   for (int i = len-1; i >= 0; i--) {

     Method* method = _methods->at(i);

     scan_method(method, true);

   }

 }

 // Creates a constant pool cache given a CPC map

 void Rewriter::make_constant_pool_cache(TRAPS) {

   const int length = _cp_cache_map.length();

   ClassLoaderData* loader_data = _pool->pool_holder()->class_loader_data();

   ConstantPoolCache* cache =

       ConstantPoolCache::allocate(loader_data, length, _cp_cache_map,

                                   _invokedynamic_references_map, CHECK);

   // initialize object cache in constant pool

   _pool->initialize_resolved_references(loader_data, _resolved_references_map,

                                         _resolved_reference_limit,

                                         CHECK);

   _pool->set_cache(cache);

   cache->set_constant_pool(_pool());

 }

 // The new finalization semantics says that registration of

 // finalizable objects must be performed on successful return from the

 // Object.<init> constructor.  We could implement this trivially if

 // <init> were never rewritten but since JVMTI allows this to occur, a

 // more complicated solution is required.  A special return bytecode

 // is used only by Object.<init> to signal the finalization

 // registration point.  Additionally local 0 must be preserved so it's

 // available to pass to the registration function.  For simplicty we

 // require that local 0 is never overwritten so it's available as an

 // argument for registration.

 void Rewriter::rewrite_Object_init(methodHandle method, TRAPS) {

   RawBytecodeStream bcs(method);

   while (!bcs.is_last_bytecode()) {

     Bytecodes::Code opcode = bcs.raw_next();

     switch (opcode) {

       case Bytecodes::_return: *bcs.bcp() = Bytecodes::_return_register_finalizer; break;

       case Bytecodes::_istore:

       case Bytecodes::_lstore:

       case Bytecodes::_fstore:

       case Bytecodes::_dstore:

       case Bytecodes::_astore:

         if (bcs.get_index() != 0) continue;

         // fall through

       case Bytecodes::_istore_0:

       case Bytecodes::_lstore_0:

       case Bytecodes::_fstore_0:

       case Bytecodes::_dstore_0:

       case Bytecodes::_astore_0:

         THROW_MSG(vmSymbols::java_lang_IncompatibleClassChangeError(),

                   "can't overwrite local 0 in Object.<init>");

         break;

     }

   }

 }

 // Rewrite a classfile-order CP index into a native-order CPC index.

 void Rewriter::rewrite_member_reference(address bcp, int offset, bool reverse) {

   address p = bcp + offset;

   if (!reverse) {

     int  cp_index    = Bytes::get_Java_u2(p);

     int  cache_index = cp_entry_to_cp_cache(cp_index);

     Bytes::put_native_u2(p, cache_index);

     if (!_method_handle_invokers.is_empty())

       maybe_rewrite_invokehandle(p - 1, cp_index, cache_index, reverse);

   } else {

     int cache_index = Bytes::get_native_u2(p);

     int pool_index = cp_cache_entry_pool_index(cache_index);

     Bytes::put_Java_u2(p, pool_index);

     if (!_method_handle_invokers.is_empty())

       maybe_rewrite_invokehandle(p - 1, pool_index, cache_index, reverse);

   }

 }

 // Adjust the invocation bytecode for a signature-polymorphic method (MethodHandle.invoke, etc.)

 void Rewriter::maybe_rewrite_invokehandle(address opc, int cp_index, int cache_index, bool reverse) {

   if (!reverse) {

     if ((*opc) == (u1)Bytecodes::_invokevirtual ||

         // allow invokespecial as an alias, although it would be very odd:

         (*opc) == (u1)Bytecodes::_invokespecial) {

       assert(_pool->tag_at(cp_index).is_method(), "wrong index");

       // Determine whether this is a signature-polymorphic method.

       if (cp_index >= _method_handle_invokers.length())  return;

       int status = _method_handle_invokers[cp_index];

       assert(status >= -1 && status <= 1, "oob tri-state");

       if (status == 0) {

         if (_pool->klass_ref_at_noresolve(cp_index) == vmSymbols::java_lang_invoke_MethodHandle() &&

             MethodHandles::is_signature_polymorphic_name(SystemDictionary::MethodHandle_klass(),

                                                          _pool->name_ref_at(cp_index))) {

           // we may need a resolved_refs entry for the appendix

           add_invokedynamic_resolved_references_entries(cp_index, cache_index);

           status = +1;

         } else {

           status = -1;

         }

         _method_handle_invokers[cp_index] = status;

       }

       // We use a special internal bytecode for such methods (if non-static).

       // The basic reason for this is that such methods need an extra "appendix" argument

       // to transmit the call site's intended call type.

       if (status > 0) {

         (*opc) = (u1)Bytecodes::_invokehandle;

       }

     }

   } else {

     // Do not need to look at cp_index.

     if ((*opc) == (u1)Bytecodes::_invokehandle) {

       (*opc) = (u1)Bytecodes::_invokevirtual;

       // Ignore corner case of original _invokespecial instruction.

       // This is safe because (a) the signature polymorphic method was final, and

       // (b) the implementation of MethodHandle will not call invokespecial on it.

     }

   }

 }

 void Rewriter::rewrite_invokedynamic(address bcp, int offset, bool reverse) {

   address p = bcp + offset;

   assert(p[-1] == Bytecodes::_invokedynamic, "not invokedynamic bytecode");

   if (!reverse) {

     int cp_index = Bytes::get_Java_u2(p);

     int cache_index = add_invokedynamic_cp_cache_entry(cp_index);

     add_invokedynamic_resolved_references_entries(cp_index, cache_index);

     // Replace the trailing four bytes with a CPC index for the dynamic

     // call site.  Unlike other CPC entries, there is one per bytecode,

     // not just one per distinct CP entry.  In other words, the

     // CPC-to-CP relation is many-to-one for invokedynamic entries.

     // This means we must use a larger index size than u2 to address

     // all these entries.  That is the main reason invokedynamic

     // must have a five-byte instruction format.  (Of course, other JVM

     // implementations can use the bytes for other purposes.)

     Bytes::put_native_u4(p, ConstantPool::encode_invokedynamic_index(cache_index));

     // Note: We use native_u4 format exclusively for 4-byte indexes.

   } else {

     // callsite index

     int cache_index = ConstantPool::decode_invokedynamic_index(

                         Bytes::get_native_u4(p));

     int cp_index = cp_cache_entry_pool_index(cache_index);

     assert(_pool->tag_at(cp_index).is_invoke_dynamic(), "wrong index");

     // zero out 4 bytes

     Bytes::put_Java_u4(p, 0);

     Bytes::put_Java_u2(p, cp_index);

   }

 }

 // Rewrite some ldc bytecodes to _fast_aldc

 void Rewriter::maybe_rewrite_ldc(address bcp, int offset, bool is_wide,

                                  bool reverse) {

   if (!reverse) {

     assert((*bcp) == (is_wide ? Bytecodes::_ldc_w : Bytecodes::_ldc), "not ldc bytecode");

     address p = bcp + offset;

     int cp_index = is_wide ? Bytes::get_Java_u2(p) : (u1)(*p);

     constantTag tag = _pool->tag_at(cp_index).value();

     if (tag.is_method_handle() || tag.is_method_type() || tag.is_string()) {

       int ref_index = cp_entry_to_resolved_references(cp_index);

       if (is_wide) {

         (*bcp) = Bytecodes::_fast_aldc_w;

         assert(ref_index == (u2)ref_index, "index overflow");

         Bytes::put_native_u2(p, ref_index);

       } else {

         (*bcp) = Bytecodes::_fast_aldc;

         assert(ref_index == (u1)ref_index, "index overflow");

         (*p) = (u1)ref_index;

       }

     }

   } else {

     Bytecodes::Code rewritten_bc =

               (is_wide ? Bytecodes::_fast_aldc_w : Bytecodes::_fast_aldc);

     if ((*bcp) == rewritten_bc) {

       address p = bcp + offset;

       int ref_index = is_wide ? Bytes::get_native_u2(p) : (u1)(*p);

       int pool_index = resolved_references_entry_to_pool_index(ref_index);

       if (is_wide) {

         (*bcp) = Bytecodes::_ldc_w;

         assert(pool_index == (u2)pool_index, "index overflow");

         Bytes::put_Java_u2(p, pool_index);

       } else {

         (*bcp) = Bytecodes::_ldc;

         assert(pool_index == (u1)pool_index, "index overflow");

         (*p) = (u1)pool_index;

       }

     }

   }

 }

 // Rewrites a method given the index_map information

 void Rewriter::scan_method(Method* method, bool reverse) {

   int nof_jsrs = 0;

   bool has_monitor_bytecodes = false;

   {

     // We cannot tolerate a GC in this block, because we've

     // cached the bytecodes in 'code_base'. If the Method*

     // moves, the bytecodes will also move.

     No_Safepoint_Verifier nsv;

     Bytecodes::Code c;

     // Bytecodes and their length

     const address code_base = method->code_base();

     const int code_length = method->code_size();

     int bc_length;

     for (int bci = 0; bci < code_length; bci += bc_length) {

       address bcp = code_base + bci;

       int prefix_length = 0;

       c = (Bytecodes::Code)(*bcp);

       // Since we have the code, see if we can get the length

       // directly. Some more complicated bytecodes will report

       // a length of zero, meaning we need to make another method

       // call to calculate the length.

       bc_length = Bytecodes::length_for(c);

       if (bc_length == 0) {

         bc_length = Bytecodes::length_at(method, bcp);

         // length_at will put us at the bytecode after the one modified

         // by 'wide'. We don't currently examine any of the bytecodes

         // modified by wide, but in case we do in the future...

         if (c == Bytecodes::_wide) {

           prefix_length = 1;

           c = (Bytecodes::Code)bcp[1];

         }

       }

       assert(bc_length != 0, "impossible bytecode length");

       switch (c) {

         case Bytecodes::_lookupswitch   : {

 #ifndef CC_INTERP

           Bytecode_lookupswitch bc(method, bcp);

           (*bcp) = (

             bc.number_of_pairs() < BinarySwitchThreshold

             ? Bytecodes::_fast_linearswitch

             : Bytecodes::_fast_binaryswitch

           );

 #endif

           break;

         }

         case Bytecodes::_fast_linearswitch:

         case Bytecodes::_fast_binaryswitch: {

 #ifndef CC_INTERP

           (*bcp) = Bytecodes::_lookupswitch;

 #endif

           break;

         }

         case Bytecodes::_getstatic      : // fall through

         case Bytecodes::_putstatic      : // fall through

         case Bytecodes::_getfield       : // fall through

         case Bytecodes::_putfield       : // fall through

         case Bytecodes::_invokevirtual  : // fall through

         case Bytecodes::_invokespecial  : // fall through

         case Bytecodes::_invokestatic   :

         case Bytecodes::_invokeinterface:

         case Bytecodes::_invokehandle   : // if reverse=true

           rewrite_member_reference(bcp, prefix_length+1, reverse);

           break;

         case Bytecodes::_invokedynamic:

           rewrite_invokedynamic(bcp, prefix_length+1, reverse);

           break;

         case Bytecodes::_ldc:

         case Bytecodes::_fast_aldc:  // if reverse=true

           maybe_rewrite_ldc(bcp, prefix_length+1, false, reverse);

           break;

         case Bytecodes::_ldc_w:

         case Bytecodes::_fast_aldc_w:  // if reverse=true

           maybe_rewrite_ldc(bcp, prefix_length+1, true, reverse);

           break;

         case Bytecodes::_jsr            : // fall through

         case Bytecodes::_jsr_w          : nof_jsrs++;                   break;

         case Bytecodes::_monitorenter   : // fall through

         case Bytecodes::_monitorexit    : has_monitor_bytecodes = true; break;

       }

     }

   }

   // Update access flags

   if (has_monitor_bytecodes) {

     method->set_has_monitor_bytecodes();

   }

   // The present of a jsr bytecode implies that the method might potentially

   // have to be rewritten, so we run the oopMapGenerator on the method

   if (nof_jsrs > 0) {

     method->set_has_jsrs();

     // Second pass will revisit this method.

     assert(method->has_jsrs(), "didn't we just set this?");

   }

 }

 // After constant pool is created, revisit methods containing jsrs.

 methodHandle Rewriter::rewrite_jsrs(methodHandle method, TRAPS) {

   ResourceMark rm(THREAD);

   ResolveOopMapConflicts romc(method);

   methodHandle original_method = method;

   method = romc.do_potential_rewrite(CHECK_(methodHandle()));

   // Update monitor matching info.

   if (romc.monitor_safe()) {

     method->set_guaranteed_monitor_matching();

   }

   return method;

 }

 void Rewriter::rewrite(instanceKlassHandle klass, TRAPS) {

   ResourceMark rm(THREAD);

   Rewriter     rw(klass, klass->constants(), klass->methods(), CHECK);

   // (That's all, folks.)

 }

 Rewriter::Rewriter(instanceKlassHandle klass, constantPoolHandle cpool, Array<Method*>* methods, TRAPS)

   : _klass(klass),

     _pool(cpool),

     _methods(methods)

 {

   assert(_pool->cache() == NULL, "constant pool cache must not be set yet");

   // determine index maps for Method* rewriting

   compute_index_maps();

   if (RegisterFinalizersAtInit && _klass->name() == vmSymbols::java_lang_Object()) {

     bool did_rewrite = false;

     int i = _methods->length();

     while (i-- > 0) {

       Method* method = _methods->at(i);

       if (method->intrinsic_id() == vmIntrinsics::_Object_init) {

         // rewrite the return bytecodes of Object.<init> to register the

         // object for finalization if needed.

         methodHandle m(THREAD, method);

         rewrite_Object_init(m, CHECK);

         did_rewrite = true;

         break;

       }

     }

     assert(did_rewrite, "must find Object::<init> to rewrite it");

   }

   // rewrite methods, in two passes

   int len = _methods->length();

   for (int i = len-1; i >= 0; i--) {

     Method* method = _methods->at(i);

     scan_method(method);

   }

   // allocate constant pool cache, now that we've seen all the bytecodes

   make_constant_pool_cache(THREAD);

   // Restore bytecodes to their unrewritten state if there are exceptions

   // rewriting bytecodes or allocating the cpCache

   if (HAS_PENDING_EXCEPTION) {

     restore_bytecodes();

     return;

   }

   // Relocate after everything, but still do this under the is_rewritten flag,

   // so methods with jsrs in custom class lists in aren't attempted to be

   // rewritten in the RO section of the shared archive.

   // Relocated bytecodes don't have to be restored, only the cp cache entries

   for (int i = len-1; i >= 0; i--) {

     methodHandle m(THREAD, _methods->at(i));

     if (m->has_jsrs()) {

       m = rewrite_jsrs(m, THREAD);

       // Restore bytecodes to their unrewritten state if there are exceptions

       // relocating bytecodes.  If some are relocated, that is ok because that

       // doesn't affect constant pool to cpCache rewriting.

       if (HAS_PENDING_EXCEPTION) {

         restore_bytecodes();

         return;

       }

       // Method might have gotten rewritten.

       methods->at_put(i, m());

     }

   }

 }