truffle: src/share/vm/ci/ciField.cpp comparison

comparison src/share/vm/ci/ciField.cpp @ 0:a61af66fc99e jdk7-b24

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author	duke
date	Sat, 01 Dec 2007 00:00:00 +0000
parents
children	dd57230ba8fe

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+:a61af66fc99e
+/*
+* 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);
+}

Mercurial > hg > truffle

comparison src/share/vm/ci/ciField.cpp @ 0:a61af66fc99e jdk7-b24