src/hotspot/share/code/exceptionHandlerTable.hpp
changeset 47216 71c04702a3d5
parent 46625 edefffab74e2
child 49373 47b5652f2928
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/code/exceptionHandlerTable.hpp	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,166 @@
+/*
+ * 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 VALUE_OBJ_CLASS_SPEC {
+ 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<intptr_t>* handler_bcis, // the exception handler entry point bcis
+    GrowableArray<intptr_t>* 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<intptr_t>* 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 <excp-offset, const-offset>.
+
+// Use 32-bit representation for offsets
+typedef  uint              implicit_null_entry;
+
+class ImplicitExceptionTable VALUE_OBJ_CLASS_SPEC {
+  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