--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/ci/ciField.cpp Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,333 @@
+/*
+ * Copyright 1999-2007 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(klass, sig_index, ignore);
+ } 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(klass, holder_index,
+ holder_is_accessible)
+ ->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");
+}
+
+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() && this->is_static()) {
+ // 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);
+}