| /* |
| * Copyright (c) 1999, 2015, 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 "ci/ciField.hpp" |
| #include "ci/ciInstanceKlass.hpp" |
| #include "ci/ciUtilities.hpp" |
| #include "classfile/systemDictionary.hpp" |
| #include "gc/shared/collectedHeap.inline.hpp" |
| #include "interpreter/linkResolver.hpp" |
| #include "memory/universe.inline.hpp" |
| #include "oops/oop.inline.hpp" |
| #include "runtime/fieldDescriptor.hpp" |
| |
| // 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_put(NULL), _known_to_link_with_get(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 constant-pool"); |
| |
| constantPoolHandle cpool(thread, klass->get_instanceKlass()->constants()); |
| |
| // Get the field's name, signature, and type. |
| Symbol* name = cpool->name_ref_at(index); |
| _name = ciEnv::current(thread)->get_symbol(name); |
| |
| int nt_index = cpool->name_and_type_ref_index_at(index); |
| int sig_index = cpool->signature_ref_index_at(nt_index); |
| Symbol* signature = cpool->symbol_at(sig_index); |
| _signature = ciEnv::current(thread)->get_symbol(signature); |
| |
| 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_symbol(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; |
| |
| ciKlass* generic_declared_holder = ciEnv::current(thread)->get_klass_by_index(cpool, holder_index, |
| holder_is_accessible, |
| klass); |
| |
| if (generic_declared_holder->is_array_klass()) { |
| // If the declared holder of the field is an array class, assume that |
| // the canonical holder of that field is java.lang.Object. Arrays |
| // do not have fields; java.lang.Object is the only supertype of an |
| // array type that can declare fields and is therefore the canonical |
| // holder of the array type. |
| // |
| // Furthermore, the compilers assume that java.lang.Object does not |
| // have any fields. Therefore, the field is not looked up. Instead, |
| // the method returns partial information that will trigger special |
| // handling in ciField::will_link and will result in a |
| // java.lang.NoSuchFieldError exception being thrown by the compiled |
| // code (the expected behavior in this case). |
| _holder = ciEnv::current(thread)->Object_klass(); |
| _offset = -1; |
| _is_constant = false; |
| return; |
| } |
| |
| ciInstanceKlass* declared_holder = generic_declared_holder->as_instance_klass(); |
| |
| // The declared holder of this field may not have been loaded. |
| // Bail out with partial field information. |
| if (!holder_is_accessible) { |
| // _type has 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; |
| Klass* 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; |
| } |
| |
| // Access check based on declared_holder. canonical_holder should not be used |
| // to check access because it can erroneously succeed. If this check fails, |
| // propagate the declared holder to will_link() which in turn will bail out |
| // compilation for this field access. |
| if (!Reflection::verify_field_access(klass->get_Klass(), declared_holder->get_Klass(), canonical_holder, field_desc.access_flags(), true)) { |
| _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_put(NULL), _known_to_link_with_get(NULL) { |
| ASSERT_IN_VM; |
| |
| // Get the field's name, signature, and type. |
| ciEnv* env = CURRENT_ENV; |
| _name = env->get_symbol(fd->name()); |
| _signature = env->get_symbol(fd->signature()); |
| |
| 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/lang/invoke") || holder->is_in_package("sun/invoke")) |
| return true; |
| // Trust VM anonymous classes. They are private API (sun.misc.Unsafe) and can't be serialized, |
| // so there is no hacking of finals going on with them. |
| if (holder->is_anonymous()) |
| return true; |
| // Trust final fields in all boxed classes |
| if (holder->is_box_klass()) |
| return true; |
| // Trust final fields in String |
| if (holder->name() == ciSymbol::java_lang_String()) |
| return true; |
| // Trust Atomic*FieldUpdaters: they are very important for performance, and make up one |
| // more reason not to use Unsafe, if their final fields are trusted. See more in JDK-8140483. |
| if (holder->name() == ciSymbol::java_util_concurrent_atomic_AtomicIntegerFieldUpdater_Impl() || |
| holder->name() == ciSymbol::java_util_concurrent_atomic_AtomicLongFieldUpdater_CASUpdater() || |
| holder->name() == ciSymbol::java_util_concurrent_atomic_AtomicLongFieldUpdater_LockedUpdater() || |
| holder->name() == ciSymbol::java_util_concurrent_atomic_AtomicReferenceFieldUpdater_Impl()) { |
| 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_instance_klass(fd->field_holder()); |
| |
| // Check to see if the field is constant. |
| Klass* k = _holder->get_Klass(); |
| bool is_stable_field = FoldStableValues && is_stable(); |
| if ((is_final() && !has_initialized_final_update()) || is_stable_field) { |
| if (is_static()) { |
| // This field just may be constant. The only case where it will |
| // not be constant is when 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. |
| 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; |
| } else { |
| // An instance field can be constant if it's a final static field or if |
| // it's a final non-static field of a trusted class (classes in |
| // java.lang.invoke and sun.invoke packages and subpackages). |
| _is_constant = is_stable_field || trust_final_non_static_fields(_holder); |
| } |
| } else { |
| // For CallSite objects treat the target field as a compile time constant. |
| assert(SystemDictionary::CallSite_klass() != NULL, "should be already initialized"); |
| if (k == SystemDictionary::CallSite_klass() && |
| _offset == java_lang_invoke_CallSite::target_offset_in_bytes()) { |
| assert(!has_initialized_final_update(), "CallSite is not supposed to have writes to final fields outside initializers"); |
| _is_constant = true; |
| } else { |
| // Non-final & non-stable fields are not constants. |
| _is_constant = false; |
| } |
| } |
| } |
| |
| // ------------------------------------------------------------------ |
| // ciField::constant_value |
| // Get the constant value of a this static field. |
| ciConstant ciField::constant_value() { |
| assert(is_static() && is_constant(), "illegal call to constant_value()"); |
| if (!_holder->is_initialized()) { |
| return ciConstant(); // Not initialized yet |
| } |
| if (_constant_value.basic_type() == T_ILLEGAL) { |
| // Static fields are placed in mirror objects. |
| VM_ENTRY_MARK; |
| ciInstance* mirror = CURRENT_ENV->get_instance(_holder->get_Klass()->java_mirror()); |
| _constant_value = mirror->field_value_impl(type()->basic_type(), offset()); |
| } |
| if (FoldStableValues && is_stable() && _constant_value.is_null_or_zero()) { |
| return ciConstant(); |
| } |
| return _constant_value; |
| } |
| |
| // ------------------------------------------------------------------ |
| // ciField::constant_value_of |
| // Get the constant value of non-static final field in the given object. |
| ciConstant ciField::constant_value_of(ciObject* object) { |
| assert(!is_static() && is_constant(), "only if field is non-static constant"); |
| assert(object->is_instance(), "must be instance"); |
| ciConstant field_value = object->as_instance()->field_value(this); |
| if (FoldStableValues && is_stable() && field_value.is_null_or_zero()) { |
| return ciConstant(); |
| } |
| return field_value; |
| } |
| |
| // ------------------------------------------------------------------ |
| // 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, constantPoolHandle(), _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(ciMethod* accessing_method, |
| Bytecodes::Code bc) { |
| VM_ENTRY_MARK; |
| assert(bc == Bytecodes::_getstatic || bc == Bytecodes::_putstatic || |
| bc == Bytecodes::_getfield || bc == Bytecodes::_putfield, |
| "unexpected bytecode"); |
| |
| 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; |
| } |
| |
| // Check for static/nonstatic mismatch |
| bool is_static = (bc == Bytecodes::_getstatic || bc == Bytecodes::_putstatic); |
| if (is_static != this->is_static()) { |
| return false; |
| } |
| |
| // Get and put can have different accessibility rules |
| bool is_put = (bc == Bytecodes::_putfield || bc == Bytecodes::_putstatic); |
| if (is_put) { |
| if (_known_to_link_with_put == accessing_method) { |
| return true; |
| } |
| } else { |
| if (_known_to_link_with_get == accessing_method->holder()) { |
| return true; |
| } |
| } |
| |
| LinkInfo link_info(_holder->get_instanceKlass(), |
| _name->get_symbol(), _signature->get_symbol(), |
| accessing_method->get_Method()); |
| fieldDescriptor result; |
| LinkResolver::resolve_field(result, link_info, bc, false, KILL_COMPILE_ON_FATAL_(false)); |
| |
| // update the hit-cache, unless there is a problem with memory scoping: |
| if (accessing_method->holder()->is_shared() || !is_shared()) { |
| if (is_put) { |
| _known_to_link_with_put = accessing_method; |
| } else { |
| _known_to_link_with_get = accessing_method->holder(); |
| } |
| } |
| |
| return true; |
| } |
| |
| // ------------------------------------------------------------------ |
| // ciField::print |
| void ciField::print() { |
| tty->print("<ciField name="); |
| _holder->print_name(); |
| tty->print("."); |
| _name->print_symbol(); |
| tty->print(" signature="); |
| _signature->print_symbol(); |
| tty->print(" offset=%d type=", _offset); |
| if (_type != NULL) |
| _type->print_name(); |
| else |
| tty->print("(reference)"); |
| tty->print(" flags=%04x", flags().as_int()); |
| tty->print(" is_constant=%s", bool_to_str(_is_constant)); |
| if (_is_constant && is_static()) { |
| 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); |
| } |