--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/ci/ciField.cpp Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,425 @@
+/*
+ * 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);
+}