Quelle rewriter.cpp Sprache: C

/*
* Copyright (c) 1998, 2022, 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
* questions.
*
*/

#include "precompiled.hpp"
#include "cds/metaspaceShared.hpp"
#include "classfile/vmClasses.hpp"
#include "interpreter/bytecodes.hpp"
#include "interpreter/interpreter.hpp"
#include "interpreter/rewriter.hpp"
#include "memory/metadataFactory.hpp"
#include "memory/resourceArea.hpp"
#include "oops/constantPool.hpp"
#include "oops/generateOopMap.hpp"
#include "prims/methodHandles.hpp"
#include "runtime/arguments.hpp"
#include "runtime/fieldDescriptor.inline.hpp"
#include "runtime/handles.inline.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_Dynamic:
        assert(_pool->has_dynamic_constant(), "constant pool's _has_dynamic_constant flag not set");
        add_resolved_references_entry(i);
        break;
      case JVM_CONSTANT_String            : // fall through
      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() ||
            _pool->symbol_at(i) == vmSymbols::java_lang_invoke_VarHandle()) {
          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.at_grow(length, 0);
  }
}

// Unrewrite the bytecodes if an error occurs.
void Rewriter::restore_bytecodes(Thread* thread) {
  int len = _methods->length();
  bool invokespecial_error = false;

  for (int i = len-1; i >= 0; i--) {
    Method* method = _methods->at(i);
    scan_method(thread, method, true, &invokespecial_error);
    assert(!invokespecial_error, "reversing should not get an invokespecial error");
  }
}

// Creates a constant pool cache given a CPC map
void Rewriter::make_constant_pool_cache(TRAPS) {
  ClassLoaderData* loader_data = _pool->pool_holder()->class_loader_data();
  ConstantPoolCache* cache =
      ConstantPoolCache::allocate(loader_data, _cp_cache_map,
                                  _invokedynamic_cp_cache_map,
                                  _invokedynamic_references_map, CHECK);

  // initialize object cache in constant pool
  _pool->set_cache(cache);
  cache->set_constant_pool(_pool());

  // _resolved_references is stored in pool->cache(), so need to be done after
  // the above lines.
  _pool->initialize_resolved_references(loader_data, _resolved_references_map,
                                        _resolved_reference_limit,
                                        THREAD);
#if INCLUDE_CDS
  if (!HAS_PENDING_EXCEPTION && Arguments::is_dumping_archive()) {
    if (_pool->pool_holder()->is_shared()) {
      assert(DynamicDumpSharedSpaces, "must be");
      // We are linking a shared class from the base archive. This
      // class won't be written into the dynamic archive, so there's no
      // need to save its CpCaches.
    } else {
      cache->save_for_archive(THREAD);
    }
  }
#endif

  // Clean up constant pool cache if initialize_resolved_references() failed.
  if (HAS_PENDING_EXCEPTION) {
    MetadataFactory::free_metadata(loader_data, cache);
    _pool->set_cache(NULL);  // so the verifier isn't confused
  }
}

// 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 simplicity we
// require that local 0 is never overwritten so it's available as an
// argument for registration.

void Rewriter::rewrite_Object_init(const 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.");
        break;

      default:
        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);
  }
}

// If the constant pool entry for invokespecial is InterfaceMethodref,
// we need to add a separate cpCache entry for its resolution, because it is
// different than the resolution for invokeinterface with InterfaceMethodref.
// These cannot share cpCache entries.
void Rewriter::rewrite_invokespecial(address bcp, int offset, bool reverse, bool* invokespecial_error) {
  address p = bcp + offset;
  if (!reverse) {
    int cp_index = Bytes::get_Java_u2(p);
    if (_pool->tag_at(cp_index).is_interface_method()) {
      int cache_index = add_invokespecial_cp_cache_entry(cp_index);
      if (cache_index != (int)(jushort) cache_index) {
        *invokespecial_error = true;
      }
      Bytes::put_native_u2(p, cache_index);
    } else {
      rewrite_member_reference(bcp, offset, reverse);
    }
  } else {
    rewrite_member_reference(bcp, offset, 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.at(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(vmClasses::MethodHandle_klass(),
                                                         _pool->name_ref_at(cp_index))) {
          // we may need a resolved_refs entry for the appendix
          add_invokedynamic_resolved_references_entry(cp_index, cache_index);
          status = +1;
        } else if (_pool->klass_ref_at_noresolve(cp_index) == vmSymbols::java_lang_invoke_VarHandle() &&
                   MethodHandles::is_signature_polymorphic_name(vmClasses::VarHandle_klass(),
                                                                _pool->name_ref_at(cp_index))) {
          // we may need a resolved_refs entry for the appendix
          add_invokedynamic_resolved_references_entry(cp_index, cache_index);
          status = +1;
        } else {
          status = -1;
        }
        _method_handle_invokers.at(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);
    int resolved_index = add_invokedynamic_resolved_references_entry(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.)
    // Note: We use native_u4 format exclusively for 4-byte indexes.
    Bytes::put_native_u4(p, ConstantPool::encode_invokedynamic_index(cache_index));
    // add the bcp in case we need to patch this bytecode if we also find a
    // invokespecial/InterfaceMethodref in the bytecode stream
    _patch_invokedynamic_bcps->push(p);
    _patch_invokedynamic_refs->push(resolved_index);
  } else {
    int cache_index = ConstantPool::decode_invokedynamic_index(
                        Bytes::get_native_u4(p));
    // We will reverse the bytecode rewriting _after_ adjusting them.
    // Adjust the cache index by offset to the invokedynamic entries in the
    // cpCache plus the delta if the invokedynamic bytecodes were adjusted.
    int adjustment = cp_cache_delta() + _first_iteration_cp_cache_limit;
    int cp_index = invokedynamic_cp_cache_entry_pool_index(cache_index - adjustment);
    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);
  }
}

void Rewriter::patch_invokedynamic_bytecodes() {
  // If the end of the cp_cache is the same as after initializing with the
  // cpool, nothing needs to be done.  Invokedynamic bytecodes are at the
  // correct offsets. ie. no invokespecials added
  int delta = cp_cache_delta();
  if (delta > 0) {
    int length = _patch_invokedynamic_bcps->length();
    assert(length == _patch_invokedynamic_refs->length(),
           "lengths should match");
    for (int i = 0; i < length; i++) {
      address p = _patch_invokedynamic_bcps->at(i);
      int cache_index = ConstantPool::decode_invokedynamic_index(
                          Bytes::get_native_u4(p));
      Bytes::put_native_u4(p, ConstantPool::encode_invokedynamic_index(cache_index + delta));

      // invokedynamic resolved references map also points to cp cache and must
      // add delta to each.
      int resolved_index = _patch_invokedynamic_refs->at(i);
        assert(_invokedynamic_references_map.at(resolved_index) == cache_index,
             "should be the same index");
        _invokedynamic_references_map.at_put(resolved_index, cache_index + delta);
    }
  }
}

// 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() ||
        (tag.is_dynamic_constant() &&
         // keep regular ldc interpreter logic for condy primitives
         is_reference_type(Signature::basic_type(_pool->uncached_signature_ref_at(cp_index))))
        ) {
      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(Thread* thread, Method* method, bool reverse, bool* invokespecial_error) {

  int nof_jsrs = 0;
  bool has_monitor_bytecodes = false;
  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];
      }
    }

    // Continuing with an invalid bytecode will fail in the loop below.
    // So guarantee here.
    guarantee(bc_length > 0, "Verifier should have caught this invalid bytecode");

    switch (c) {
      case Bytecodes::_lookupswitch   : {
#ifndef ZERO
        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 ZERO
        (*bcp) = Bytecodes::_lookupswitch;
#endif
        break;
      }

      case Bytecodes::_invokespecial  : {
        rewrite_invokespecial(bcp, prefix_length+1, reverse, invokespecial_error);
        break;
      }

      case Bytecodes::_putstatic      :
      case Bytecodes::_putfield       : {
        if (!reverse) {
          // Check if any final field of the class given as parameter is modified
          // outside of initializer methods of the class. Fields that are modified
          // are marked with a flag. For marked fields, the compilers do not perform
          // constant folding (as the field can be changed after initialization).
          //
          // The check is performed after verification and only if verification has
          // succeeded. Therefore, the class is guaranteed to be well-formed.
          InstanceKlass* klass = method->method_holder();
          u2 bc_index = Bytes::get_Java_u2(bcp + prefix_length + 1);
          constantPoolHandle cp(thread, method->constants());
          Symbol* ref_class_name = cp->klass_name_at(cp->klass_ref_index_at(bc_index));

          if (klass->name() == ref_class_name) {
            Symbol* field_name = cp->name_ref_at(bc_index);
            Symbol* field_sig = cp->signature_ref_at(bc_index);

            fieldDescriptor fd;
            if (klass->find_field(field_name, field_sig, &fd) != NULL) {
              if (fd.access_flags().is_final()) {
                if (fd.access_flags().is_static()) {
                  if (!method->is_static_initializer()) {
                    fd.set_has_initialized_final_update(true);
                  }
                } else {
                  if (!method->is_object_initializer()) {
                    fd.set_has_initialized_final_update(true);
                  }
                }
              }
            }
          }
        }
      }
      // fall through
      case Bytecodes::_getstatic      : // fall through
      case Bytecodes::_getfield       : // fall through
      case Bytecodes::_invokevirtual  : // 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;

      default: 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(const methodHandle& method, TRAPS) {
  ResourceMark rm(THREAD);
  ResolveOopMapConflicts romc(method);
  methodHandle new_method = romc.do_potential_rewrite(CHECK_(methodHandle()));
  // Update monitor matching info.
  if (romc.monitor_safe()) {
    new_method->set_guaranteed_monitor_matching();
  }

  return new_method;
}

void Rewriter::rewrite_bytecodes(TRAPS) {
  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:: to rewrite it");
  }

  // rewrite methods, in two passes
  int len = _methods->length();
  bool invokespecial_error = false;

  for (int i = len-1; i >= 0; i--) {
    Method* method = _methods->at(i);
    scan_method(THREAD, method, false, &invokespecial_error);
    if (invokespecial_error) {
      // If you get an error here, there is no reversing bytecodes
      // This exception is stored for this class and no further attempt is
      // made at verifying or rewriting.
      THROW_MSG(vmSymbols::java_lang_InternalError(),
                "This classfile overflows invokespecial for interfaces "
                "and cannot be loaded");
      return;
     }
  }

  // May have to fix invokedynamic bytecodes if invokestatic/InterfaceMethodref
  // entries had to be added.
  patch_invokedynamic_bytecodes();
}

void Rewriter::rewrite(InstanceKlass* klass, TRAPS) {
#if INCLUDE_CDS
  if (klass->is_shared()) {
    assert(!klass->is_rewritten(), "rewritten shared classes cannot be rewritten again");
  }
#endif // INCLUDE_CDS
  ResourceMark rm(THREAD);
  constantPoolHandle cpool(THREAD, klass->constants());
  Rewriter     rw(klass, cpool, klass->methods(), CHECK);
  // (That's all, folks.)
}

Rewriter::Rewriter(InstanceKlass* klass, const constantPoolHandle& cpool, Array<Method*>* methods, TRAPS)
  : _klass(klass),
    _pool(cpool),
    _methods(methods),
    _cp_map(cpool->length()),
    _cp_cache_map(cpool->length() / 2),
    _reference_map(cpool->length()),
    _resolved_references_map(cpool->length() / 2),
    _invokedynamic_references_map(cpool->length() / 2),
    _method_handle_invokers(cpool->length()),
    _invokedynamic_cp_cache_map(cpool->length() / 4)
{

  // Rewrite bytecodes - exception here exits.
  rewrite_bytecodes(CHECK);

  // Stress restoring bytecodes
  if (StressRewriter) {
    restore_bytecodes(THREAD);
    rewrite_bytecodes(CHECK);
  }

  // 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(THREAD);
    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
  int len = _methods->length();
  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(THREAD);
        return;
      }
      // Method might have gotten rewritten.
      methods->at_put(i, m());
    }
  }
}

quality94%

¤ Dauer der Verarbeitung: 0.16 Sekunden (vorverarbeitet) ¤

Wurzel

Suchen

Beweissystem der NASA

Beweissystem Isabelle

NIST Cobol Testsuite

Cephes Mathematical Library

Wiener Entwicklungsmethode

Haftungshinweis

Die Informationen auf dieser Webseite wurden nach bestem Wissen sorgfältig zusammengestellt. Es wird jedoch weder Vollständigkeit, noch Richtigkeit, noch Qualität der bereit gestellten Informationen zugesichert.

Bemerkung:

Die farbliche Syntaxdarstellung ist noch experimentell.