1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/share/vm/ci/ciField.cpp Wed Apr 27 01:25:04 2016 +0800
1.3 @@ -0,0 +1,409 @@
1.4 +/*
1.5 + * Copyright (c) 1999, 2013, Oracle and/or its affiliates. All rights reserved.
1.6 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.7 + *
1.8 + * This code is free software; you can redistribute it and/or modify it
1.9 + * under the terms of the GNU General Public License version 2 only, as
1.10 + * published by the Free Software Foundation.
1.11 + *
1.12 + * This code is distributed in the hope that it will be useful, but WITHOUT
1.13 + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.14 + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.15 + * version 2 for more details (a copy is included in the LICENSE file that
1.16 + * accompanied this code).
1.17 + *
1.18 + * You should have received a copy of the GNU General Public License version
1.19 + * 2 along with this work; if not, write to the Free Software Foundation,
1.20 + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.21 + *
1.22 + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
1.23 + * or visit www.oracle.com if you need additional information or have any
1.24 + * questions.
1.25 + *
1.26 + */
1.27 +
1.28 +#include "precompiled.hpp"
1.29 +#include "ci/ciField.hpp"
1.30 +#include "ci/ciInstanceKlass.hpp"
1.31 +#include "ci/ciUtilities.hpp"
1.32 +#include "classfile/systemDictionary.hpp"
1.33 +#include "gc_interface/collectedHeap.inline.hpp"
1.34 +#include "interpreter/linkResolver.hpp"
1.35 +#include "memory/universe.inline.hpp"
1.36 +#include "oops/oop.inline.hpp"
1.37 +#include "oops/oop.inline2.hpp"
1.38 +#include "runtime/fieldDescriptor.hpp"
1.39 +
1.40 +// ciField
1.41 +//
1.42 +// This class represents the result of a field lookup in the VM.
1.43 +// The lookup may not succeed, in which case the information in
1.44 +// the ciField will be incomplete.
1.45 +
1.46 +// The ciObjectFactory cannot create circular data structures in one query.
1.47 +// To avoid vicious circularities, we initialize ciField::_type to NULL
1.48 +// for reference types and derive it lazily from the ciField::_signature.
1.49 +// Primitive types are eagerly initialized, and basic layout queries
1.50 +// can succeed without initialization, using only the BasicType of the field.
1.51 +
1.52 +// Notes on bootstrapping and shared CI objects: A field is shared if and
1.53 +// only if it is (a) non-static and (b) declared by a shared instance klass.
1.54 +// This allows non-static field lists to be cached on shared types.
1.55 +// Because the _type field is lazily initialized, however, there is a
1.56 +// special restriction that a shared field cannot cache an unshared type.
1.57 +// This puts a small performance penalty on shared fields with unshared
1.58 +// types, such as StackTraceElement[] Throwable.stackTrace.
1.59 +// (Throwable is shared because ClassCastException is shared, but
1.60 +// StackTraceElement is not presently shared.)
1.61 +
1.62 +// It is not a vicious circularity for a ciField to recursively create
1.63 +// the ciSymbols necessary to represent its name and signature.
1.64 +// Therefore, these items are created eagerly, and the name and signature
1.65 +// of a shared field are themselves shared symbols. This somewhat
1.66 +// pollutes the set of shared CI objects: It grows from 50 to 93 items,
1.67 +// with all of the additional 43 being uninteresting shared ciSymbols.
1.68 +// This adds at most one step to the binary search, an amount which
1.69 +// decreases for complex compilation tasks.
1.70 +
1.71 +// ------------------------------------------------------------------
1.72 +// ciField::ciField
1.73 +ciField::ciField(ciInstanceKlass* klass, int index): _known_to_link_with_put(NULL), _known_to_link_with_get(NULL) {
1.74 + ASSERT_IN_VM;
1.75 + CompilerThread *thread = CompilerThread::current();
1.76 +
1.77 + assert(ciObjectFactory::is_initialized(), "not a shared field");
1.78 +
1.79 + assert(klass->get_instanceKlass()->is_linked(), "must be linked before using its constan-pool");
1.80 +
1.81 + constantPoolHandle cpool(thread, klass->get_instanceKlass()->constants());
1.82 +
1.83 + // Get the field's name, signature, and type.
1.84 + Symbol* name = cpool->name_ref_at(index);
1.85 + _name = ciEnv::current(thread)->get_symbol(name);
1.86 +
1.87 + int nt_index = cpool->name_and_type_ref_index_at(index);
1.88 + int sig_index = cpool->signature_ref_index_at(nt_index);
1.89 + Symbol* signature = cpool->symbol_at(sig_index);
1.90 + _signature = ciEnv::current(thread)->get_symbol(signature);
1.91 +
1.92 + BasicType field_type = FieldType::basic_type(signature);
1.93 +
1.94 + // If the field is a pointer type, get the klass of the
1.95 + // field.
1.96 + if (field_type == T_OBJECT || field_type == T_ARRAY) {
1.97 + bool ignore;
1.98 + // This is not really a class reference; the index always refers to the
1.99 + // field's type signature, as a symbol. Linkage checks do not apply.
1.100 + _type = ciEnv::current(thread)->get_klass_by_index(cpool, sig_index, ignore, klass);
1.101 + } else {
1.102 + _type = ciType::make(field_type);
1.103 + }
1.104 +
1.105 + _name = (ciSymbol*)ciEnv::current(thread)->get_symbol(name);
1.106 +
1.107 + // Get the field's declared holder.
1.108 + //
1.109 + // Note: we actually create a ciInstanceKlass for this klass,
1.110 + // even though we may not need to.
1.111 + int holder_index = cpool->klass_ref_index_at(index);
1.112 + bool holder_is_accessible;
1.113 + ciInstanceKlass* declared_holder =
1.114 + ciEnv::current(thread)->get_klass_by_index(cpool, holder_index,
1.115 + holder_is_accessible,
1.116 + klass)->as_instance_klass();
1.117 +
1.118 + // The declared holder of this field may not have been loaded.
1.119 + // Bail out with partial field information.
1.120 + if (!holder_is_accessible) {
1.121 + // _type has already been set.
1.122 + // The default values for _flags and _constant_value will suffice.
1.123 + // We need values for _holder, _offset, and _is_constant,
1.124 + _holder = declared_holder;
1.125 + _offset = -1;
1.126 + _is_constant = false;
1.127 + return;
1.128 + }
1.129 +
1.130 + InstanceKlass* loaded_decl_holder = declared_holder->get_instanceKlass();
1.131 +
1.132 + // Perform the field lookup.
1.133 + fieldDescriptor field_desc;
1.134 + Klass* canonical_holder =
1.135 + loaded_decl_holder->find_field(name, signature, &field_desc);
1.136 + if (canonical_holder == NULL) {
1.137 + // Field lookup failed. Will be detected by will_link.
1.138 + _holder = declared_holder;
1.139 + _offset = -1;
1.140 + _is_constant = false;
1.141 + return;
1.142 + }
1.143 +
1.144 + // Access check based on declared_holder. canonical_holder should not be used
1.145 + // to check access because it can erroneously succeed. If this check fails,
1.146 + // propagate the declared holder to will_link() which in turn will bail out
1.147 + // compilation for this field access.
1.148 + if (!Reflection::verify_field_access(klass->get_Klass(), declared_holder->get_Klass(), canonical_holder, field_desc.access_flags(), true)) {
1.149 + _holder = declared_holder;
1.150 + _offset = -1;
1.151 + _is_constant = false;
1.152 + return;
1.153 + }
1.154 +
1.155 + assert(canonical_holder == field_desc.field_holder(), "just checking");
1.156 + initialize_from(&field_desc);
1.157 +}
1.158 +
1.159 +ciField::ciField(fieldDescriptor *fd): _known_to_link_with_put(NULL), _known_to_link_with_get(NULL) {
1.160 + ASSERT_IN_VM;
1.161 +
1.162 + // Get the field's name, signature, and type.
1.163 + ciEnv* env = CURRENT_ENV;
1.164 + _name = env->get_symbol(fd->name());
1.165 + _signature = env->get_symbol(fd->signature());
1.166 +
1.167 + BasicType field_type = fd->field_type();
1.168 +
1.169 + // If the field is a pointer type, get the klass of the
1.170 + // field.
1.171 + if (field_type == T_OBJECT || field_type == T_ARRAY) {
1.172 + _type = NULL; // must call compute_type on first access
1.173 + } else {
1.174 + _type = ciType::make(field_type);
1.175 + }
1.176 +
1.177 + initialize_from(fd);
1.178 +
1.179 + // Either (a) it is marked shared, or else (b) we are done bootstrapping.
1.180 + assert(is_shared() || ciObjectFactory::is_initialized(),
1.181 + "bootstrap classes must not create & cache unshared fields");
1.182 +}
1.183 +
1.184 +static bool trust_final_non_static_fields(ciInstanceKlass* holder) {
1.185 + if (holder == NULL)
1.186 + return false;
1.187 + if (holder->name() == ciSymbol::java_lang_System())
1.188 + // Never trust strangely unstable finals: System.out, etc.
1.189 + return false;
1.190 + // Even if general trusting is disabled, trust system-built closures in these packages.
1.191 + if (holder->is_in_package("java/lang/invoke") || holder->is_in_package("sun/invoke"))
1.192 + return true;
1.193 + return TrustFinalNonStaticFields;
1.194 +}
1.195 +
1.196 +void ciField::initialize_from(fieldDescriptor* fd) {
1.197 + // Get the flags, offset, and canonical holder of the field.
1.198 + _flags = ciFlags(fd->access_flags());
1.199 + _offset = fd->offset();
1.200 + _holder = CURRENT_ENV->get_instance_klass(fd->field_holder());
1.201 +
1.202 + // Check to see if the field is constant.
1.203 + bool is_final = this->is_final();
1.204 + bool is_stable = FoldStableValues && this->is_stable();
1.205 + if (_holder->is_initialized() && (is_final || is_stable)) {
1.206 + if (!this->is_static()) {
1.207 + // A field can be constant if it's a final static field or if
1.208 + // it's a final non-static field of a trusted class (classes in
1.209 + // java.lang.invoke and sun.invoke packages and subpackages).
1.210 + if (is_stable || trust_final_non_static_fields(_holder)) {
1.211 + _is_constant = true;
1.212 + return;
1.213 + }
1.214 + _is_constant = false;
1.215 + return;
1.216 + }
1.217 +
1.218 + // This field just may be constant. The only cases where it will
1.219 + // not be constant are:
1.220 + //
1.221 + // 1. The field holds a non-perm-space oop. The field is, strictly
1.222 + // speaking, constant but we cannot embed non-perm-space oops into
1.223 + // generated code. For the time being we need to consider the
1.224 + // field to be not constant.
1.225 + // 2. The field is a *special* static&final field whose value
1.226 + // may change. The three examples are java.lang.System.in,
1.227 + // java.lang.System.out, and java.lang.System.err.
1.228 +
1.229 + KlassHandle k = _holder->get_Klass();
1.230 + assert( SystemDictionary::System_klass() != NULL, "Check once per vm");
1.231 + if( k() == SystemDictionary::System_klass() ) {
1.232 + // Check offsets for case 2: System.in, System.out, or System.err
1.233 + if( _offset == java_lang_System::in_offset_in_bytes() ||
1.234 + _offset == java_lang_System::out_offset_in_bytes() ||
1.235 + _offset == java_lang_System::err_offset_in_bytes() ) {
1.236 + _is_constant = false;
1.237 + return;
1.238 + }
1.239 + }
1.240 +
1.241 + Handle mirror = k->java_mirror();
1.242 +
1.243 + switch(type()->basic_type()) {
1.244 + case T_BYTE:
1.245 + _constant_value = ciConstant(type()->basic_type(), mirror->byte_field(_offset));
1.246 + break;
1.247 + case T_CHAR:
1.248 + _constant_value = ciConstant(type()->basic_type(), mirror->char_field(_offset));
1.249 + break;
1.250 + case T_SHORT:
1.251 + _constant_value = ciConstant(type()->basic_type(), mirror->short_field(_offset));
1.252 + break;
1.253 + case T_BOOLEAN:
1.254 + _constant_value = ciConstant(type()->basic_type(), mirror->bool_field(_offset));
1.255 + break;
1.256 + case T_INT:
1.257 + _constant_value = ciConstant(type()->basic_type(), mirror->int_field(_offset));
1.258 + break;
1.259 + case T_FLOAT:
1.260 + _constant_value = ciConstant(mirror->float_field(_offset));
1.261 + break;
1.262 + case T_DOUBLE:
1.263 + _constant_value = ciConstant(mirror->double_field(_offset));
1.264 + break;
1.265 + case T_LONG:
1.266 + _constant_value = ciConstant(mirror->long_field(_offset));
1.267 + break;
1.268 + case T_OBJECT:
1.269 + case T_ARRAY:
1.270 + {
1.271 + oop o = mirror->obj_field(_offset);
1.272 +
1.273 + // A field will be "constant" if it is known always to be
1.274 + // a non-null reference to an instance of a particular class,
1.275 + // or to a particular array. This can happen even if the instance
1.276 + // or array is not perm. In such a case, an "unloaded" ciArray
1.277 + // or ciInstance is created. The compiler may be able to use
1.278 + // information about the object's class (which is exact) or length.
1.279 +
1.280 + if (o == NULL) {
1.281 + _constant_value = ciConstant(type()->basic_type(), ciNullObject::make());
1.282 + } else {
1.283 + _constant_value = ciConstant(type()->basic_type(), CURRENT_ENV->get_object(o));
1.284 + assert(_constant_value.as_object() == CURRENT_ENV->get_object(o), "check interning");
1.285 + }
1.286 + }
1.287 + }
1.288 + if (is_stable && _constant_value.is_null_or_zero()) {
1.289 + // It is not a constant after all; treat it as uninitialized.
1.290 + _is_constant = false;
1.291 + } else {
1.292 + _is_constant = true;
1.293 + }
1.294 + } else {
1.295 + _is_constant = false;
1.296 + }
1.297 +}
1.298 +
1.299 +// ------------------------------------------------------------------
1.300 +// ciField::compute_type
1.301 +//
1.302 +// Lazily compute the type, if it is an instance klass.
1.303 +ciType* ciField::compute_type() {
1.304 + GUARDED_VM_ENTRY(return compute_type_impl();)
1.305 +}
1.306 +
1.307 +ciType* ciField::compute_type_impl() {
1.308 + ciKlass* type = CURRENT_ENV->get_klass_by_name_impl(_holder, constantPoolHandle(), _signature, false);
1.309 + if (!type->is_primitive_type() && is_shared()) {
1.310 + // We must not cache a pointer to an unshared type, in a shared field.
1.311 + bool type_is_also_shared = false;
1.312 + if (type->is_type_array_klass()) {
1.313 + type_is_also_shared = true; // int[] etc. are explicitly bootstrapped
1.314 + } else if (type->is_instance_klass()) {
1.315 + type_is_also_shared = type->as_instance_klass()->is_shared();
1.316 + } else {
1.317 + // Currently there is no 'shared' query for array types.
1.318 + type_is_also_shared = !ciObjectFactory::is_initialized();
1.319 + }
1.320 + if (!type_is_also_shared)
1.321 + return type; // Bummer.
1.322 + }
1.323 + _type = type;
1.324 + return type;
1.325 +}
1.326 +
1.327 +
1.328 +// ------------------------------------------------------------------
1.329 +// ciField::will_link
1.330 +//
1.331 +// Can a specific access to this field be made without causing
1.332 +// link errors?
1.333 +bool ciField::will_link(ciInstanceKlass* accessing_klass,
1.334 + Bytecodes::Code bc) {
1.335 + VM_ENTRY_MARK;
1.336 + assert(bc == Bytecodes::_getstatic || bc == Bytecodes::_putstatic ||
1.337 + bc == Bytecodes::_getfield || bc == Bytecodes::_putfield,
1.338 + "unexpected bytecode");
1.339 +
1.340 + if (_offset == -1) {
1.341 + // at creation we couldn't link to our holder so we need to
1.342 + // maintain that stance, otherwise there's no safe way to use this
1.343 + // ciField.
1.344 + return false;
1.345 + }
1.346 +
1.347 + // Check for static/nonstatic mismatch
1.348 + bool is_static = (bc == Bytecodes::_getstatic || bc == Bytecodes::_putstatic);
1.349 + if (is_static != this->is_static()) {
1.350 + return false;
1.351 + }
1.352 +
1.353 + // Get and put can have different accessibility rules
1.354 + bool is_put = (bc == Bytecodes::_putfield || bc == Bytecodes::_putstatic);
1.355 + if (is_put) {
1.356 + if (_known_to_link_with_put == accessing_klass) {
1.357 + return true;
1.358 + }
1.359 + } else {
1.360 + if (_known_to_link_with_get == accessing_klass) {
1.361 + return true;
1.362 + }
1.363 + }
1.364 +
1.365 + fieldDescriptor result;
1.366 + LinkResolver::resolve_field(result, _holder->get_instanceKlass(),
1.367 + _name->get_symbol(), _signature->get_symbol(),
1.368 + accessing_klass->get_Klass(), bc, true, false,
1.369 + KILL_COMPILE_ON_FATAL_(false));
1.370 +
1.371 + // update the hit-cache, unless there is a problem with memory scoping:
1.372 + if (accessing_klass->is_shared() || !is_shared()) {
1.373 + if (is_put) {
1.374 + _known_to_link_with_put = accessing_klass;
1.375 + } else {
1.376 + _known_to_link_with_get = accessing_klass;
1.377 + }
1.378 + }
1.379 +
1.380 + return true;
1.381 +}
1.382 +
1.383 +// ------------------------------------------------------------------
1.384 +// ciField::print
1.385 +void ciField::print() {
1.386 + tty->print("<ciField name=");
1.387 + _holder->print_name();
1.388 + tty->print(".");
1.389 + _name->print_symbol();
1.390 + tty->print(" signature=");
1.391 + _signature->print_symbol();
1.392 + tty->print(" offset=%d type=", _offset);
1.393 + if (_type != NULL)
1.394 + _type->print_name();
1.395 + else
1.396 + tty->print("(reference)");
1.397 + tty->print(" flags=%04x", flags().as_int());
1.398 + tty->print(" is_constant=%s", bool_to_str(_is_constant));
1.399 + if (_is_constant && is_static()) {
1.400 + tty->print(" constant_value=");
1.401 + _constant_value.print();
1.402 + }
1.403 + tty->print(">");
1.404 +}
1.405 +
1.406 +// ------------------------------------------------------------------
1.407 +// ciField::print_name_on
1.408 +//
1.409 +// Print the name of this field
1.410 +void ciField::print_name_on(outputStream* st) {
1.411 + name()->print_symbol_on(st);
1.412 +}
