/*

 * Copyright 1998-2005 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

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

  const int length = inverse_index_map.length();

  constantPoolCacheOop cache = oopFactory::new_constantPoolCache(length, 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());

    }

  }

}