Mercurial > jdk8-mips64-public > hotspot / file revision

 /*

  * Copyright 1998-2009 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

  * CA 95054 USA or visit www.sun.com if you need additional information or

  * have any questions.

  *

  */

 # include "incls/_precompiled.incl"

 # include "incls/_rewriter.cpp.incl"

 // Computes an index_map (new_index -> original_index) for contant pool entries

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

 void Rewriter::compute_index_maps(constantPoolHandle pool, intArray*& index_map, intStack*& inverse_index_map) {

   const int length  = pool->length();

   index_map         = new intArray(length, -1);

   // Choose an initial value large enough that we don't get frequent

   // calls to grow().

   inverse_index_map = new intStack(length / 2);

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

     switch (pool->tag_at(i).value()) {

       case JVM_CONSTANT_Fieldref          : // fall through

       case JVM_CONSTANT_Methodref         : // fall through

       case JVM_CONSTANT_InterfaceMethodref: {

         index_map->at_put(i, inverse_index_map->length());

         inverse_index_map->append(i);

       }

     }

   }

 }

 // Creates a constant pool cache given an inverse_index_map

 // This creates the constant pool cache initially in a state

 // that is unsafe for concurrent GC processing but sets it to

 // a safe mode before the constant pool cache is returned.

 constantPoolCacheHandle Rewriter::new_constant_pool_cache(intArray& inverse_index_map, TRAPS) {

   const int length = inverse_index_map.length();

   constantPoolCacheOop cache = oopFactory::new_constantPoolCache(length,

                                              methodOopDesc::IsUnsafeConc,

                                              CHECK_(constantPoolCacheHandle()));

   cache->initialize(inverse_index_map);

   return constantPoolCacheHandle(THREAD, cache);

 }

 // 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;

     }

   }

 }

 // Rewrites a method given the index_map information

 methodHandle Rewriter::rewrite_method(methodHandle method, intArray& index_map, TRAPS) {

   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 methodOop

     // 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;

       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(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) {

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

         }

       }

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

       switch (c) {

         case Bytecodes::_lookupswitch   : {

 #ifndef CC_INTERP

           Bytecode_lookupswitch* bc = Bytecode_lookupswitch_at(bcp);

           bc->set_code(

             bc->number_of_pairs() < BinarySwitchThreshold

             ? Bytecodes::_fast_linearswitch

             : Bytecodes::_fast_binaryswitch

           );

 #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   : // fall through

         case Bytecodes::_invokeinterface: {

           address p = bcp + 1;

           Bytes::put_native_u2(p, index_map[Bytes::get_Java_u2(p)]);

           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();

     ResolveOopMapConflicts romc(method);

     methodHandle original_method = method;

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

     if (method() != original_method()) {

       // Insert invalid bytecode into original methodOop and set

       // interpreter entrypoint, so that a executing this method

       // will manifest itself in an easy recognizable form.

       address bcp = original_method->bcp_from(0);

       *bcp = (u1)Bytecodes::_shouldnotreachhere;

       int kind = Interpreter::method_kind(original_method);

       original_method->set_interpreter_kind(kind);

     }

     // Update monitor matching info.

     if (romc.monitor_safe()) {

       method->set_guaranteed_monitor_matching();

     }

   }

   // Setup method entrypoints for compiler and interpreter

   method->link_method(method, CHECK_(methodHandle()));

   return method;

 }

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

   // gather starting points

   ResourceMark rm(THREAD);

   constantPoolHandle pool (THREAD, klass->constants());

   objArrayHandle methods  (THREAD, klass->methods());

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

   // determine index maps for methodOop rewriting

   intArray* index_map         = NULL;

   intStack* inverse_index_map = NULL;

   compute_index_maps(pool, index_map, inverse_index_map);

   // allocate constant pool cache

   constantPoolCacheHandle cache = new_constant_pool_cache(*inverse_index_map, CHECK);

   pool->set_cache(cache());

   cache->set_constant_pool(pool());

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

     int i = methods->length();

     while (i-- > 0) {

       methodOop method = (methodOop)methods->obj_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);

         break;

       }

     }

   }

   // rewrite methods

   { int i = methods->length();

     while (i-- > 0) {

       methodHandle m(THREAD, (methodOop)methods->obj_at(i));

       m = rewrite_method(m, *index_map, CHECK);

       // Method might have gotten rewritten.

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

     }

   }

 }