/* * Copyright (c) 1998, 2016, 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. * */ #ifndef SHARE_VM_CODE_EXCEPTIONHANDLERTABLE_HPP #define SHARE_VM_CODE_EXCEPTIONHANDLERTABLE_HPP #include "memory/allocation.hpp" #include "oops/method.hpp" #include "utilities/align.hpp" // A HandlerTableEntry describes an individual entry of a subtable // of ExceptionHandlerTable. An entry consists of a pair(bci, pco), // where bci is the exception handler bci, and pco is the pc offset // relative to the nmethod code start for the compiled exception // handler corresponding to the (interpreted) exception handler // starting at bci. // // The first HandlerTableEntry of each subtable holds the length // and catch_pco for the subtable (the length is the number of // subtable entries w/o header). class HandlerTableEntry { private: int _bci; int _pco; int _scope_depth; public: HandlerTableEntry(int bci, int pco, int scope_depth) { assert( 0 <= pco, "pco must be positive"); assert( 0 <= scope_depth, "scope_depth must be positive"); _bci = bci; _pco = pco; _scope_depth = scope_depth; } int len() const { return _bci; } // for entry at subtable begin int bci() const { return _bci; } int pco() const { return _pco; } int scope_depth() const { return _scope_depth; } }; // An ExceptionHandlerTable is an abstraction over a list of subtables // of exception handlers for CatchNodes. Each subtable has a one-entry // header holding length and catch_pco of the subtable, followed // by 'length' entries for each exception handler that can be reached // from the corresponding CatchNode. The catch_pco is the pc offset of // the CatchNode in the corresponding nmethod. Empty subtables are dis- // carded. // // Structure of the table: // // table = { subtable }. // subtable = header entry { entry }. // header = a pair (number of subtable entries, catch pc offset, [unused]) // entry = a pair (handler bci, handler pc offset, scope depth) // // An ExceptionHandlerTable can be created from scratch, in which case // it is possible to add subtables. It can also be created from an // nmethod (for lookup purposes) in which case the table cannot be // modified. class nmethod; class ExceptionHandlerTable { private: HandlerTableEntry* _table; // the table int _length; // the current length of the table int _size; // the number of allocated entries ReallocMark _nesting; // assertion check for reallocations public: // add the entry & grow the table if needed void add_entry(HandlerTableEntry entry); HandlerTableEntry* subtable_for(int catch_pco) const; // (compile-time) construction within compiler ExceptionHandlerTable(int initial_size = 8); // (run-time) construction from nmethod ExceptionHandlerTable(const CompiledMethod* nm); // (compile-time) add entries void add_subtable( int catch_pco, // the pc offset for the CatchNode GrowableArray* handler_bcis, // the exception handler entry point bcis GrowableArray* scope_depths_from_top_scope, // if representing exception handlers in multiple // inlined scopes, indicates which scope relative to // the youngest/innermost one in which we are performing // the lookup; zero (or null GrowableArray) indicates // innermost scope GrowableArray* handler_pcos // pc offsets for the compiled handlers ); // nmethod support int size_in_bytes() const { return align_up(_length * (int)sizeof(HandlerTableEntry), oopSize); } void copy_to(CompiledMethod* nm); void copy_bytes_to(address addr); // lookup HandlerTableEntry* entry_for(int catch_pco, int handler_bci, int scope_depth) const; // debugging void print_subtable(HandlerTableEntry* t) const; void print() const; void print_subtable_for(int catch_pco) const; }; // ---------------------------------------------------------------------------- // Implicit null exception tables. Maps an exception PC offset to a // continuation PC offset. During construction it's a variable sized // array with a max size and current length. When stored inside an // nmethod a zero length table takes no space. This is detected by // nul_chk_table_size() == 0. Otherwise the table has a length word // followed by pairs of . // Use 32-bit representation for offsets typedef uint implicit_null_entry; class ImplicitExceptionTable { uint _size; uint _len; implicit_null_entry *_data; implicit_null_entry *adr( uint idx ) const { return &_data[2*idx]; } ReallocMark _nesting; // assertion check for reallocations public: ImplicitExceptionTable( ) : _data(0), _size(0), _len(0) { } // (run-time) construction from nmethod ImplicitExceptionTable( const nmethod *nm ); void set_size( uint size ); void append( uint exec_off, uint cont_off ); uint at( uint exec_off ) const; uint len() const { return _len; } int size_in_bytes() const { return len() == 0 ? 0 : ((2 * len() + 1) * sizeof(implicit_null_entry)); } void copy_to(nmethod* nm); void print(address base) const; void verify(nmethod *nm) const; }; #endif // SHARE_VM_CODE_EXCEPTIONHANDLERTABLE_HPP