jdk8-mips64-public/hotspot: src/share/vm/ci/ciField.cpp@73b22f919c34 (annotated)

src/share/vm/ci/ciField.cpp@73b22f919c34 (annotated)

src/share/vm/ci/ciField.cpp

Wed, 13 Jan 2010 23:05:52 -0800

author: jrose
date: Wed, 13 Jan 2010 23:05:52 -0800
changeset 1608: 73b22f919c34
parent 1577: 4ce7240d622c
child 1907: c18cbe5936b8
permissions: -rw-r--r--

6912065: final fields in objects need to support inlining optimizations for JSR 292
Reviewed-by: twisti, kvn

 /*
  * Copyright 1999-2009 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/_ciField.cpp.incl"
 // ciField
 //
 // This class represents the result of a field lookup in the VM.
 // The lookup may not succeed, in which case the information in
 // the ciField will be incomplete.
 // The ciObjectFactory cannot create circular data structures in one query.
 // To avoid vicious circularities, we initialize ciField::_type to NULL
 // for reference types and derive it lazily from the ciField::_signature.
 // Primitive types are eagerly initialized, and basic layout queries
 // can succeed without initialization, using only the BasicType of the field.
 // Notes on bootstrapping and shared CI objects:  A field is shared if and
 // only if it is (a) non-static and (b) declared by a shared instance klass.
 // This allows non-static field lists to be cached on shared types.
 // Because the _type field is lazily initialized, however, there is a
 // special restriction that a shared field cannot cache an unshared type.
 // This puts a small performance penalty on shared fields with unshared
 // types, such as StackTraceElement[] Throwable.stackTrace.
 // (Throwable is shared because ClassCastException is shared, but
 // StackTraceElement is not presently shared.)
 // It is not a vicious circularity for a ciField to recursively create
 // the ciSymbols necessary to represent its name and signature.
 // Therefore, these items are created eagerly, and the name and signature
 // of a shared field are themselves shared symbols.  This somewhat
 // pollutes the set of shared CI objects:  It grows from 50 to 93 items,
 // with all of the additional 43 being uninteresting shared ciSymbols.
 // This adds at most one step to the binary search, an amount which
 // decreases for complex compilation tasks.
 // ------------------------------------------------------------------
 // ciField::ciField
 ciField::ciField(ciInstanceKlass* klass, int index): _known_to_link_with(NULL) {
   ASSERT_IN_VM;
   CompilerThread *thread = CompilerThread::current();
   assert(ciObjectFactory::is_initialized(), "not a shared field");
   assert(klass->get_instanceKlass()->is_linked(), "must be linked before using its constan-pool");
   _cp_index = index;
   constantPoolHandle cpool(thread, klass->get_instanceKlass()->constants());
   // Get the field's name, signature, and type.
   symbolHandle name  (thread, cpool->name_ref_at(index));
   _name = ciEnv::current(thread)->get_object(name())->as_symbol();
   int nt_index = cpool->name_and_type_ref_index_at(index);
   int sig_index = cpool->signature_ref_index_at(nt_index);
   symbolHandle signature (thread, cpool->symbol_at(sig_index));
   _signature = ciEnv::current(thread)->get_object(signature())->as_symbol();
   BasicType field_type = FieldType::basic_type(signature());
   // If the field is a pointer type, get the klass of the
   // field.
   if (field_type == T_OBJECT || field_type == T_ARRAY) {
     bool ignore;
     // This is not really a class reference; the index always refers to the
     // field's type signature, as a symbol.  Linkage checks do not apply.
     _type = ciEnv::current(thread)->get_klass_by_index(cpool, sig_index, ignore, klass);
   } else {
     _type = ciType::make(field_type);
   }
   _name = (ciSymbol*)ciEnv::current(thread)->get_object(name());
   // Get the field's declared holder.
   //
   // Note: we actually create a ciInstanceKlass for this klass,
   // even though we may not need to.
   int holder_index = cpool->klass_ref_index_at(index);
   bool holder_is_accessible;
   ciInstanceKlass* declared_holder =
     ciEnv::current(thread)->get_klass_by_index(cpool, holder_index,
                                                holder_is_accessible,
                                                klass)->as_instance_klass();
   // The declared holder of this field may not have been loaded.
   // Bail out with partial field information.
   if (!holder_is_accessible) {
     // _cp_index and _type have already been set.
     // The default values for _flags and _constant_value will suffice.
     // We need values for _holder, _offset,  and _is_constant,
     _holder = declared_holder;
     _offset = -1;
     _is_constant = false;
     return;
   }
   instanceKlass* loaded_decl_holder = declared_holder->get_instanceKlass();
   // Perform the field lookup.
   fieldDescriptor field_desc;
   klassOop canonical_holder =
     loaded_decl_holder->find_field(name(), signature(), &field_desc);
   if (canonical_holder == NULL) {
     // Field lookup failed.  Will be detected by will_link.
     _holder = declared_holder;
     _offset = -1;
     _is_constant = false;
     return;
   }
   assert(canonical_holder == field_desc.field_holder(), "just checking");
   initialize_from(&field_desc);
 }
 ciField::ciField(fieldDescriptor *fd): _known_to_link_with(NULL) {
   ASSERT_IN_VM;
   _cp_index = -1;
   // Get the field's name, signature, and type.
   ciEnv* env = CURRENT_ENV;
   _name = env->get_object(fd->name())->as_symbol();
   _signature = env->get_object(fd->signature())->as_symbol();
   BasicType field_type = fd->field_type();
   // If the field is a pointer type, get the klass of the
   // field.
   if (field_type == T_OBJECT || field_type == T_ARRAY) {
     _type = NULL;  // must call compute_type on first access
   } else {
     _type = ciType::make(field_type);
   }
   initialize_from(fd);
   // Either (a) it is marked shared, or else (b) we are done bootstrapping.
   assert(is_shared() || ciObjectFactory::is_initialized(),
          "bootstrap classes must not create & cache unshared fields");
 }
 static bool trust_final_non_static_fields(ciInstanceKlass* holder) {
   if (holder == NULL)
     return false;
   if (holder->name() == ciSymbol::java_lang_System())
     // Never trust strangely unstable finals:  System.out, etc.
     return false;
   // Even if general trusting is disabled, trust system-built closures in these packages.
   if (holder->is_in_package("java/dyn") || holder->is_in_package("sun/dyn"))
     return true;
   return TrustFinalNonStaticFields;
 }
 void ciField::initialize_from(fieldDescriptor* fd) {
   // Get the flags, offset, and canonical holder of the field.
   _flags = ciFlags(fd->access_flags());
   _offset = fd->offset();
   _holder = CURRENT_ENV->get_object(fd->field_holder())->as_instance_klass();
   // Check to see if the field is constant.
   if (_holder->is_initialized() && this->is_final()) {
     if (!this->is_static()) {
       // A field can be constant if it's a final static field or if it's
       // a final non-static field of a trusted class ({java,sun}.dyn).
       if (trust_final_non_static_fields(_holder)) {
         _is_constant = true;
         return;
       }
       _is_constant = false;
       return;
     }
     // This field just may be constant.  The only cases where it will
     // not be constant are:
     //
     // 1. The field holds a non-perm-space oop.  The field is, strictly
     //    speaking, constant but we cannot embed non-perm-space oops into
     //    generated code.  For the time being we need to consider the
     //    field to be not constant.
     // 2. The field is a *special* static&final field whose value
     //    may change.  The three examples are java.lang.System.in,
     //    java.lang.System.out, and java.lang.System.err.
     klassOop k = _holder->get_klassOop();
     assert( SystemDictionary::System_klass() != NULL, "Check once per vm");
     if( k == SystemDictionary::System_klass() ) {
       // Check offsets for case 2: System.in, System.out, or System.err
       if( _offset == java_lang_System::in_offset_in_bytes()  ||
           _offset == java_lang_System::out_offset_in_bytes() ||
           _offset == java_lang_System::err_offset_in_bytes() ) {
         _is_constant = false;
         return;
       }
     }
     _is_constant = true;
     switch(type()->basic_type()) {
     case T_BYTE:
       _constant_value = ciConstant(type()->basic_type(), k->byte_field(_offset));
       break;
     case T_CHAR:
       _constant_value = ciConstant(type()->basic_type(), k->char_field(_offset));
       break;
     case T_SHORT:
       _constant_value = ciConstant(type()->basic_type(), k->short_field(_offset));
       break;
     case T_BOOLEAN:
       _constant_value = ciConstant(type()->basic_type(), k->bool_field(_offset));
       break;
     case T_INT:
       _constant_value = ciConstant(type()->basic_type(), k->int_field(_offset));
       break;
     case T_FLOAT:
       _constant_value = ciConstant(k->float_field(_offset));
       break;
     case T_DOUBLE:
       _constant_value = ciConstant(k->double_field(_offset));
       break;
     case T_LONG:
       _constant_value = ciConstant(k->long_field(_offset));
       break;
     case T_OBJECT:
     case T_ARRAY:
       {
         oop o = k->obj_field(_offset);
         // A field will be "constant" if it is known always to be
         // a non-null reference to an instance of a particular class,
         // or to a particular array.  This can happen even if the instance
         // or array is not perm.  In such a case, an "unloaded" ciArray
         // or ciInstance is created.  The compiler may be able to use
         // information about the object's class (which is exact) or length.
         if (o == NULL) {
           _constant_value = ciConstant(type()->basic_type(), ciNullObject::make());
         } else {
           _constant_value = ciConstant(type()->basic_type(), CURRENT_ENV->get_object(o));
           assert(_constant_value.as_object() == CURRENT_ENV->get_object(o), "check interning");
         }
       }
     }
   } else {
     _is_constant = false;
   }
 }
 // ------------------------------------------------------------------
 // ciField::compute_type
 //
 // Lazily compute the type, if it is an instance klass.
 ciType* ciField::compute_type() {
   GUARDED_VM_ENTRY(return compute_type_impl();)
 }
 ciType* ciField::compute_type_impl() {
   ciKlass* type = CURRENT_ENV->get_klass_by_name_impl(_holder, _signature, false);
   if (!type->is_primitive_type() && is_shared()) {
     // We must not cache a pointer to an unshared type, in a shared field.
     bool type_is_also_shared = false;
     if (type->is_type_array_klass()) {
       type_is_also_shared = true;  // int[] etc. are explicitly bootstrapped
     } else if (type->is_instance_klass()) {
       type_is_also_shared = type->as_instance_klass()->is_shared();
     } else {
       // Currently there is no 'shared' query for array types.
       type_is_also_shared = !ciObjectFactory::is_initialized();
     }
     if (!type_is_also_shared)
       return type;              // Bummer.
   }
   _type = type;
   return type;
 }
 // ------------------------------------------------------------------
 // ciField::will_link
 //
 // Can a specific access to this field be made without causing
 // link errors?
 bool ciField::will_link(ciInstanceKlass* accessing_klass,
                         Bytecodes::Code bc) {
   VM_ENTRY_MARK;
   if (_offset == -1) {
     // at creation we couldn't link to our holder so we need to
     // maintain that stance, otherwise there's no safe way to use this
     // ciField.
     return false;
   }
   if (_known_to_link_with == accessing_klass) {
     return true;
   }
   FieldAccessInfo result;
   constantPoolHandle c_pool(THREAD,
                          accessing_klass->get_instanceKlass()->constants());
   LinkResolver::resolve_field(result, c_pool, _cp_index,
                               Bytecodes::java_code(bc),
                               true, false, KILL_COMPILE_ON_FATAL_(false));
   // update the hit-cache, unless there is a problem with memory scoping:
   if (accessing_klass->is_shared() || !is_shared())
     _known_to_link_with = accessing_klass;
   return true;
 }
 // ------------------------------------------------------------------
 // ciField::print
 void ciField::print() {
   tty->print("<ciField ");
   _holder->print_name();
   tty->print(".");
   _name->print_symbol();
   tty->print(" offset=%d type=", _offset);
   if (_type != NULL) _type->print_name();
   else               tty->print("(reference)");
   tty->print(" is_constant=%s", bool_to_str(_is_constant));
   if (_is_constant) {
     tty->print(" constant_value=");
     _constant_value.print();
   }
   tty->print(">");
 }
 // ------------------------------------------------------------------
 // ciField::print_name_on
 //
 // Print the name of this field
 void ciField::print_name_on(outputStream* st) {
   name()->print_symbol_on(st);
 }

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/ci/ciField.cpp@73b22f919c34 (annotated)

src/share/vm/ci/ciField.cpp