duke@435: /*
drchase@5732:  * Copyright (c) 1999, 2013, Oracle and/or its affiliates. All rights reserved.
duke@435:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@435:  *
duke@435:  * This code is free software; you can redistribute it and/or modify it
duke@435:  * under the terms of the GNU General Public License version 2 only, as
duke@435:  * published by the Free Software Foundation.
duke@435:  *
duke@435:  * This code is distributed in the hope that it will be useful, but WITHOUT
duke@435:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@435:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
duke@435:  * version 2 for more details (a copy is included in the LICENSE file that
duke@435:  * accompanied this code).
duke@435:  *
duke@435:  * You should have received a copy of the GNU General Public License version
duke@435:  * 2 along with this work; if not, write to the Free Software Foundation,
duke@435:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@435:  *
trims@1907:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
trims@1907:  * or visit www.oracle.com if you need additional information or have any
trims@1907:  * questions.
duke@435:  *
duke@435:  */
duke@435: 
stefank@2314: #include "precompiled.hpp"
stefank@2314: #include "ci/ciField.hpp"
stefank@2314: #include "ci/ciInstanceKlass.hpp"
stefank@2314: #include "ci/ciUtilities.hpp"
stefank@2314: #include "classfile/systemDictionary.hpp"
stefank@2314: #include "gc_interface/collectedHeap.inline.hpp"
stefank@2314: #include "interpreter/linkResolver.hpp"
stefank@2314: #include "memory/universe.inline.hpp"
stefank@2314: #include "oops/oop.inline.hpp"
stefank@2314: #include "oops/oop.inline2.hpp"
stefank@2314: #include "runtime/fieldDescriptor.hpp"
duke@435: 
duke@435: // ciField
duke@435: //
duke@435: // This class represents the result of a field lookup in the VM.
duke@435: // The lookup may not succeed, in which case the information in
duke@435: // the ciField will be incomplete.
duke@435: 
duke@435: // The ciObjectFactory cannot create circular data structures in one query.
duke@435: // To avoid vicious circularities, we initialize ciField::_type to NULL
duke@435: // for reference types and derive it lazily from the ciField::_signature.
duke@435: // Primitive types are eagerly initialized, and basic layout queries
duke@435: // can succeed without initialization, using only the BasicType of the field.
duke@435: 
duke@435: // Notes on bootstrapping and shared CI objects:  A field is shared if and
duke@435: // only if it is (a) non-static and (b) declared by a shared instance klass.
duke@435: // This allows non-static field lists to be cached on shared types.
duke@435: // Because the _type field is lazily initialized, however, there is a
duke@435: // special restriction that a shared field cannot cache an unshared type.
duke@435: // This puts a small performance penalty on shared fields with unshared
duke@435: // types, such as StackTraceElement[] Throwable.stackTrace.
duke@435: // (Throwable is shared because ClassCastException is shared, but
duke@435: // StackTraceElement is not presently shared.)
duke@435: 
duke@435: // It is not a vicious circularity for a ciField to recursively create
duke@435: // the ciSymbols necessary to represent its name and signature.
duke@435: // Therefore, these items are created eagerly, and the name and signature
duke@435: // of a shared field are themselves shared symbols.  This somewhat
duke@435: // pollutes the set of shared CI objects:  It grows from 50 to 93 items,
duke@435: // with all of the additional 43 being uninteresting shared ciSymbols.
duke@435: // This adds at most one step to the binary search, an amount which
duke@435: // decreases for complex compilation tasks.
duke@435: 
duke@435: // ------------------------------------------------------------------
duke@435: // ciField::ciField
never@3854: ciField::ciField(ciInstanceKlass* klass, int index): _known_to_link_with_put(NULL), _known_to_link_with_get(NULL) {
duke@435:   ASSERT_IN_VM;
duke@435:   CompilerThread *thread = CompilerThread::current();
duke@435: 
duke@435:   assert(ciObjectFactory::is_initialized(), "not a shared field");
duke@435: 
duke@435:   assert(klass->get_instanceKlass()->is_linked(), "must be linked before using its constan-pool");
duke@435: 
duke@435:   constantPoolHandle cpool(thread, klass->get_instanceKlass()->constants());
duke@435: 
duke@435:   // Get the field's name, signature, and type.
coleenp@2497:   Symbol* name  = cpool->name_ref_at(index);
coleenp@2497:   _name = ciEnv::current(thread)->get_symbol(name);
duke@435: 
duke@435:   int nt_index = cpool->name_and_type_ref_index_at(index);
duke@435:   int sig_index = cpool->signature_ref_index_at(nt_index);
coleenp@2497:   Symbol* signature = cpool->symbol_at(sig_index);
coleenp@2497:   _signature = ciEnv::current(thread)->get_symbol(signature);
duke@435: 
coleenp@2497:   BasicType field_type = FieldType::basic_type(signature);
duke@435: 
duke@435:   // If the field is a pointer type, get the klass of the
duke@435:   // field.
duke@435:   if (field_type == T_OBJECT || field_type == T_ARRAY) {
duke@435:     bool ignore;
duke@435:     // This is not really a class reference; the index always refers to the
duke@435:     // field's type signature, as a symbol.  Linkage checks do not apply.
twisti@1573:     _type = ciEnv::current(thread)->get_klass_by_index(cpool, sig_index, ignore, klass);
duke@435:   } else {
duke@435:     _type = ciType::make(field_type);
duke@435:   }
duke@435: 
coleenp@2497:   _name = (ciSymbol*)ciEnv::current(thread)->get_symbol(name);
duke@435: 
duke@435:   // Get the field's declared holder.
duke@435:   //
duke@435:   // Note: we actually create a ciInstanceKlass for this klass,
duke@435:   // even though we may not need to.
duke@435:   int holder_index = cpool->klass_ref_index_at(index);
duke@435:   bool holder_is_accessible;
duke@435:   ciInstanceKlass* declared_holder =
twisti@1573:     ciEnv::current(thread)->get_klass_by_index(cpool, holder_index,
twisti@1573:                                                holder_is_accessible,
twisti@1573:                                                klass)->as_instance_klass();
duke@435: 
duke@435:   // The declared holder of this field may not have been loaded.
duke@435:   // Bail out with partial field information.
duke@435:   if (!holder_is_accessible) {
drchase@5732:     // _type has already been set.
duke@435:     // The default values for _flags and _constant_value will suffice.
duke@435:     // We need values for _holder, _offset,  and _is_constant,
duke@435:     _holder = declared_holder;
duke@435:     _offset = -1;
duke@435:     _is_constant = false;
duke@435:     return;
duke@435:   }
duke@435: 
coleenp@4037:   InstanceKlass* loaded_decl_holder = declared_holder->get_instanceKlass();
duke@435: 
duke@435:   // Perform the field lookup.
duke@435:   fieldDescriptor field_desc;
coleenp@4037:   Klass* canonical_holder =
coleenp@2497:     loaded_decl_holder->find_field(name, signature, &field_desc);
duke@435:   if (canonical_holder == NULL) {
duke@435:     // Field lookup failed.  Will be detected by will_link.
duke@435:     _holder = declared_holder;
duke@435:     _offset = -1;
duke@435:     _is_constant = false;
duke@435:     return;
duke@435:   }
duke@435: 
duke@435:   assert(canonical_holder == field_desc.field_holder(), "just checking");
duke@435:   initialize_from(&field_desc);
duke@435: }
duke@435: 
never@3854: ciField::ciField(fieldDescriptor *fd): _known_to_link_with_put(NULL), _known_to_link_with_get(NULL) {
duke@435:   ASSERT_IN_VM;
duke@435: 
duke@435:   // Get the field's name, signature, and type.
duke@435:   ciEnv* env = CURRENT_ENV;
coleenp@2497:   _name = env->get_symbol(fd->name());
coleenp@2497:   _signature = env->get_symbol(fd->signature());
duke@435: 
duke@435:   BasicType field_type = fd->field_type();
duke@435: 
duke@435:   // If the field is a pointer type, get the klass of the
duke@435:   // field.
duke@435:   if (field_type == T_OBJECT || field_type == T_ARRAY) {
duke@435:     _type = NULL;  // must call compute_type on first access
duke@435:   } else {
duke@435:     _type = ciType::make(field_type);
duke@435:   }
duke@435: 
duke@435:   initialize_from(fd);
duke@435: 
duke@435:   // Either (a) it is marked shared, or else (b) we are done bootstrapping.
duke@435:   assert(is_shared() || ciObjectFactory::is_initialized(),
duke@435:          "bootstrap classes must not create & cache unshared fields");
duke@435: }
duke@435: 
jrose@1608: static bool trust_final_non_static_fields(ciInstanceKlass* holder) {
jrose@1608:   if (holder == NULL)
jrose@1608:     return false;
jrose@1608:   if (holder->name() == ciSymbol::java_lang_System())
jrose@1608:     // Never trust strangely unstable finals:  System.out, etc.
jrose@1608:     return false;
jrose@1608:   // Even if general trusting is disabled, trust system-built closures in these packages.
jrose@2639:   if (holder->is_in_package("java/lang/invoke") || holder->is_in_package("sun/invoke"))
jrose@1608:     return true;
jrose@1608:   return TrustFinalNonStaticFields;
jrose@1608: }
jrose@1608: 
duke@435: void ciField::initialize_from(fieldDescriptor* fd) {
duke@435:   // Get the flags, offset, and canonical holder of the field.
duke@435:   _flags = ciFlags(fd->access_flags());
duke@435:   _offset = fd->offset();
coleenp@4037:   _holder = CURRENT_ENV->get_instance_klass(fd->field_holder());
duke@435: 
duke@435:   // Check to see if the field is constant.
vlivanov@5658:   bool is_final = this->is_final();
vlivanov@5658:   bool is_stable = FoldStableValues && this->is_stable();
vlivanov@5658:   if (_holder->is_initialized() && (is_final || is_stable)) {
twisti@1573:     if (!this->is_static()) {
jrose@2639:       // A field can be constant if it's a final static field or if
jrose@2639:       // it's a final non-static field of a trusted class (classes in
jrose@2639:       // java.lang.invoke and sun.invoke packages and subpackages).
vlivanov@5658:       if (is_stable || trust_final_non_static_fields(_holder)) {
twisti@1573:         _is_constant = true;
twisti@1573:         return;
twisti@1573:       }
twisti@1573:       _is_constant = false;
twisti@1573:       return;
twisti@1573:     }
twisti@1573: 
duke@435:     // This field just may be constant.  The only cases where it will
duke@435:     // not be constant are:
duke@435:     //
duke@435:     // 1. The field holds a non-perm-space oop.  The field is, strictly
duke@435:     //    speaking, constant but we cannot embed non-perm-space oops into
duke@435:     //    generated code.  For the time being we need to consider the
duke@435:     //    field to be not constant.
duke@435:     // 2. The field is a *special* static&final field whose value
duke@435:     //    may change.  The three examples are java.lang.System.in,
duke@435:     //    java.lang.System.out, and java.lang.System.err.
duke@435: 
coleenp@4037:     KlassHandle k = _holder->get_Klass();
never@1577:     assert( SystemDictionary::System_klass() != NULL, "Check once per vm");
never@2568:     if( k() == SystemDictionary::System_klass() ) {
duke@435:       // Check offsets for case 2: System.in, System.out, or System.err
duke@435:       if( _offset == java_lang_System::in_offset_in_bytes()  ||
duke@435:           _offset == java_lang_System::out_offset_in_bytes() ||
duke@435:           _offset == java_lang_System::err_offset_in_bytes() ) {
duke@435:         _is_constant = false;
duke@435:         return;
duke@435:       }
duke@435:     }
duke@435: 
never@2658:     Handle mirror = k->java_mirror();
never@2658: 
duke@435:     switch(type()->basic_type()) {
duke@435:     case T_BYTE:
never@2658:       _constant_value = ciConstant(type()->basic_type(), mirror->byte_field(_offset));
duke@435:       break;
duke@435:     case T_CHAR:
never@2658:       _constant_value = ciConstant(type()->basic_type(), mirror->char_field(_offset));
duke@435:       break;
duke@435:     case T_SHORT:
never@2658:       _constant_value = ciConstant(type()->basic_type(), mirror->short_field(_offset));
duke@435:       break;
duke@435:     case T_BOOLEAN:
never@2658:       _constant_value = ciConstant(type()->basic_type(), mirror->bool_field(_offset));
duke@435:       break;
duke@435:     case T_INT:
never@2658:       _constant_value = ciConstant(type()->basic_type(), mirror->int_field(_offset));
duke@435:       break;
duke@435:     case T_FLOAT:
never@2658:       _constant_value = ciConstant(mirror->float_field(_offset));
duke@435:       break;
duke@435:     case T_DOUBLE:
never@2658:       _constant_value = ciConstant(mirror->double_field(_offset));
duke@435:       break;
duke@435:     case T_LONG:
never@2658:       _constant_value = ciConstant(mirror->long_field(_offset));
duke@435:       break;
duke@435:     case T_OBJECT:
duke@435:     case T_ARRAY:
duke@435:       {
never@2658:         oop o = mirror->obj_field(_offset);
duke@435: 
duke@435:         // A field will be "constant" if it is known always to be
duke@435:         // a non-null reference to an instance of a particular class,
duke@435:         // or to a particular array.  This can happen even if the instance
duke@435:         // or array is not perm.  In such a case, an "unloaded" ciArray
duke@435:         // or ciInstance is created.  The compiler may be able to use
duke@435:         // information about the object's class (which is exact) or length.
duke@435: 
duke@435:         if (o == NULL) {
duke@435:           _constant_value = ciConstant(type()->basic_type(), ciNullObject::make());
duke@435:         } else {
duke@435:           _constant_value = ciConstant(type()->basic_type(), CURRENT_ENV->get_object(o));
duke@435:           assert(_constant_value.as_object() == CURRENT_ENV->get_object(o), "check interning");
duke@435:         }
duke@435:       }
duke@435:     }
vlivanov@5658:     if (is_stable && _constant_value.is_null_or_zero()) {
vlivanov@5658:       // It is not a constant after all; treat it as uninitialized.
vlivanov@5658:       _is_constant = false;
vlivanov@5658:     } else {
vlivanov@5658:       _is_constant = true;
vlivanov@5658:     }
duke@435:   } else {
duke@435:     _is_constant = false;
duke@435:   }
duke@435: }
duke@435: 
duke@435: // ------------------------------------------------------------------
duke@435: // ciField::compute_type
duke@435: //
duke@435: // Lazily compute the type, if it is an instance klass.
duke@435: ciType* ciField::compute_type() {
duke@435:   GUARDED_VM_ENTRY(return compute_type_impl();)
duke@435: }
duke@435: 
duke@435: ciType* ciField::compute_type_impl() {
jrose@2982:   ciKlass* type = CURRENT_ENV->get_klass_by_name_impl(_holder, constantPoolHandle(), _signature, false);
duke@435:   if (!type->is_primitive_type() && is_shared()) {
duke@435:     // We must not cache a pointer to an unshared type, in a shared field.
duke@435:     bool type_is_also_shared = false;
duke@435:     if (type->is_type_array_klass()) {
duke@435:       type_is_also_shared = true;  // int[] etc. are explicitly bootstrapped
duke@435:     } else if (type->is_instance_klass()) {
duke@435:       type_is_also_shared = type->as_instance_klass()->is_shared();
duke@435:     } else {
duke@435:       // Currently there is no 'shared' query for array types.
duke@435:       type_is_also_shared = !ciObjectFactory::is_initialized();
duke@435:     }
duke@435:     if (!type_is_also_shared)
duke@435:       return type;              // Bummer.
duke@435:   }
duke@435:   _type = type;
duke@435:   return type;
duke@435: }
duke@435: 
duke@435: 
duke@435: // ------------------------------------------------------------------
duke@435: // ciField::will_link
duke@435: //
duke@435: // Can a specific access to this field be made without causing
duke@435: // link errors?
duke@435: bool ciField::will_link(ciInstanceKlass* accessing_klass,
duke@435:                         Bytecodes::Code bc) {
duke@435:   VM_ENTRY_MARK;
never@3854:   assert(bc == Bytecodes::_getstatic || bc == Bytecodes::_putstatic ||
never@3854:          bc == Bytecodes::_getfield  || bc == Bytecodes::_putfield,
never@3854:          "unexpected bytecode");
never@3854: 
duke@435:   if (_offset == -1) {
duke@435:     // at creation we couldn't link to our holder so we need to
duke@435:     // maintain that stance, otherwise there's no safe way to use this
duke@435:     // ciField.
duke@435:     return false;
duke@435:   }
duke@435: 
never@3854:   // Check for static/nonstatic mismatch
never@3854:   bool is_static = (bc == Bytecodes::_getstatic || bc == Bytecodes::_putstatic);
never@3854:   if (is_static != this->is_static()) {
never@3854:     return false;
never@3854:   }
never@3854: 
never@3854:   // Get and put can have different accessibility rules
never@3854:   bool is_put    = (bc == Bytecodes::_putfield  || bc == Bytecodes::_putstatic);
never@3854:   if (is_put) {
never@3854:     if (_known_to_link_with_put == accessing_klass) {
never@3854:       return true;
never@3854:     }
never@3856:   } else {
never@3854:     if (_known_to_link_with_get == accessing_klass) {
never@3854:       return true;
never@3854:     }
duke@435:   }
duke@435: 
drchase@5732:   fieldDescriptor result;
drchase@5732:   LinkResolver::resolve_field(result, _holder->get_instanceKlass(),
drchase@5732:                               _name->get_symbol(), _signature->get_symbol(),
drchase@5732:                               accessing_klass->get_Klass(), bc, true, false,
drchase@5732:                               KILL_COMPILE_ON_FATAL_(false));
duke@435: 
duke@435:   // update the hit-cache, unless there is a problem with memory scoping:
never@3854:   if (accessing_klass->is_shared() || !is_shared()) {
never@3854:     if (is_put) {
never@3854:       _known_to_link_with_put = accessing_klass;
never@3854:     } else {
never@3854:       _known_to_link_with_get = accessing_klass;
never@3854:     }
never@3854:   }
duke@435: 
duke@435:   return true;
duke@435: }
duke@435: 
duke@435: // ------------------------------------------------------------------
duke@435: // ciField::print
duke@435: void ciField::print() {
roland@4357:   tty->print("<ciField name=");
duke@435:   _holder->print_name();
duke@435:   tty->print(".");
duke@435:   _name->print_symbol();
roland@4357:   tty->print(" signature=");
roland@4357:   _signature->print_symbol();
duke@435:   tty->print(" offset=%d type=", _offset);
vlivanov@5658:   if (_type != NULL)
vlivanov@5658:     _type->print_name();
vlivanov@5658:   else
vlivanov@5658:     tty->print("(reference)");
vlivanov@5658:   tty->print(" flags=%04x", flags().as_int());
duke@435:   tty->print(" is_constant=%s", bool_to_str(_is_constant));
kvn@2037:   if (_is_constant && is_static()) {
duke@435:     tty->print(" constant_value=");
duke@435:     _constant_value.print();
duke@435:   }
duke@435:   tty->print(">");
duke@435: }
duke@435: 
duke@435: // ------------------------------------------------------------------
duke@435: // ciField::print_name_on
duke@435: //
duke@435: // Print the name of this field
duke@435: void ciField::print_name_on(outputStream* st) {
duke@435:   name()->print_symbol_on(st);
duke@435: }