diff -r 000000000000 -r f90c822e73f8 src/share/vm/ci/ciField.cpp --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/share/vm/ci/ciField.cpp Wed Apr 27 01:25:04 2016 +0800 @@ -0,0 +1,409 @@ +/* + * Copyright (c) 1999, 2013, 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_interface/collectedHeap.inline.hpp" +#include "interpreter/linkResolver.hpp" +#include "memory/universe.inline.hpp" +#include "oops/oop.inline.hpp" +#include "oops/oop.inline2.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 constan-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; + ciInstanceKlass* declared_holder = + ciEnv::current(thread)->get_klass_by_index(cpool, holder_index, + holder_is_accessible, + klass)->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; + 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. + bool is_final = this->is_final(); + bool is_stable = FoldStableValues && this->is_stable(); + if (_holder->is_initialized() && (is_final || is_stable)) { + if (!this->is_static()) { + // A 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). + if (is_stable || trust_final_non_static_fields(_holder)) { + _is_constant = true; + return; + } + _is_constant = false; + return; + } + + // 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. + + KlassHandle k = _holder->get_Klass(); + 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; + } + } + + Handle mirror = k->java_mirror(); + + switch(type()->basic_type()) { + case T_BYTE: + _constant_value = ciConstant(type()->basic_type(), mirror->byte_field(_offset)); + break; + case T_CHAR: + _constant_value = ciConstant(type()->basic_type(), mirror->char_field(_offset)); + break; + case T_SHORT: + _constant_value = ciConstant(type()->basic_type(), mirror->short_field(_offset)); + break; + case T_BOOLEAN: + _constant_value = ciConstant(type()->basic_type(), mirror->bool_field(_offset)); + break; + case T_INT: + _constant_value = ciConstant(type()->basic_type(), mirror->int_field(_offset)); + break; + case T_FLOAT: + _constant_value = ciConstant(mirror->float_field(_offset)); + break; + case T_DOUBLE: + _constant_value = ciConstant(mirror->double_field(_offset)); + break; + case T_LONG: + _constant_value = ciConstant(mirror->long_field(_offset)); + break; + case T_OBJECT: + case T_ARRAY: + { + oop o = mirror->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"); + } + } + } + if (is_stable && _constant_value.is_null_or_zero()) { + // It is not a constant after all; treat it as uninitialized. + _is_constant = false; + } else { + _is_constant = true; + } + } 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, 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(ciInstanceKlass* accessing_klass, + 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_klass) { + return true; + } + } else { + if (_known_to_link_with_get == accessing_klass) { + return true; + } + } + + fieldDescriptor result; + LinkResolver::resolve_field(result, _holder->get_instanceKlass(), + _name->get_symbol(), _signature->get_symbol(), + accessing_klass->get_Klass(), 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()) { + if (is_put) { + _known_to_link_with_put = accessing_klass; + } else { + _known_to_link_with_get = accessing_klass; + } + } + + return true; +} + +// ------------------------------------------------------------------ +// ciField::print +void ciField::print() { + tty->print("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); +}