Mercurial > hg > graal-jvmci-8
diff src/share/vm/ci/ciField.cpp @ 0:a61af66fc99e jdk7-b24
Initial load
author | duke |
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date | Sat, 01 Dec 2007 00:00:00 +0000 |
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children | dd57230ba8fe |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/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); +}