view src/share/vm/code/exceptionHandlerTable.cpp @ 20543:e7d0505c8a30

8059758: Footprint regressions with JDK-8038423 Summary: Changes in JDK-8038423 always initialize (zero out) virtual memory used for auxiliary data structures. This causes a footprint regression for G1 in startup benchmarks. This is because they do not touch that memory at all, so the operating system does not actually commit these pages. The fix is to, if the initialization value of the data structures matches the default value of just committed memory (=0), do not do anything. Reviewed-by: jwilhelm, brutisso
author tschatzl
date Fri, 10 Oct 2014 15:51:58 +0200
parents 78bbf4d43a14
children
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/*
 * Copyright (c) 1998, 2014, 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 "code/exceptionHandlerTable.hpp"
#include "code/nmethod.hpp"
#include "memory/allocation.inline.hpp"

PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC

void ExceptionHandlerTable::add_entry(HandlerTableEntry entry) {
  _nesting.check();
  if (_length >= _size) {
    // not enough space => grow the table (amortized growth, double its size)
    guarantee(_size > 0, "no space allocated => cannot grow the table since it is part of nmethod");
    int new_size = _size * 2;
    _table = REALLOC_RESOURCE_ARRAY(HandlerTableEntry, _table, _size, new_size);
    _size = new_size;
  }
  assert(_length < _size, "sanity check");
  _table[_length++] = entry;
}


HandlerTableEntry* ExceptionHandlerTable::subtable_for(int catch_pco) const {
  int i = 0;
  while (i < _length) {
    HandlerTableEntry* t = _table + i;
    if (t->pco() == catch_pco) {
      // found subtable matching the catch_pco
      return t;
    } else {
      // advance to next subtable
      i += t->len() + 1; // +1 for header
    }
  }
  return NULL;
}


ExceptionHandlerTable::ExceptionHandlerTable(int initial_size) {
  guarantee(initial_size > 0, "initial size must be > 0");
  _table  = NEW_RESOURCE_ARRAY(HandlerTableEntry, initial_size);
  _length = 0;
  _size   = initial_size;
}


ExceptionHandlerTable::ExceptionHandlerTable(const nmethod* nm) {
  _table  = (HandlerTableEntry*)nm->handler_table_begin();
  _length = nm->handler_table_size() / sizeof(HandlerTableEntry);
  _size   = 0; // no space allocated by ExeptionHandlerTable!
}


void ExceptionHandlerTable::add_subtable(
  int                 catch_pco,
  GrowableArray<intptr_t>* handler_bcis,
  GrowableArray<intptr_t>* scope_depths_from_top_scope,
  GrowableArray<intptr_t>* handler_pcos
) {
  assert(subtable_for(catch_pco) == NULL, "catch handlers for this catch_pco added twice");
  assert(handler_bcis->length() == handler_pcos->length(), "bci & pc table have different length");
  assert(scope_depths_from_top_scope == NULL || handler_bcis->length() == scope_depths_from_top_scope->length(), "bci & scope_depths table have different length");
  if (handler_bcis->length() > 0) {
    // add subtable header
    add_entry(HandlerTableEntry(handler_bcis->length(), catch_pco, 0));
    // add individual entries
    for (int i = 0; i < handler_bcis->length(); i++) {
      intptr_t scope_depth = 0;
      if (scope_depths_from_top_scope != NULL) {
        scope_depth = scope_depths_from_top_scope->at(i);
      }
      add_entry(HandlerTableEntry(handler_bcis->at(i), handler_pcos->at(i), scope_depth));
      assert(entry_for(catch_pco, handler_bcis->at(i), scope_depth)->pco() == handler_pcos->at(i), "entry not added correctly (1)");
      assert(entry_for(catch_pco, handler_bcis->at(i), scope_depth)->scope_depth() == scope_depth, "entry not added correctly (2)");
    }
  }
}


void ExceptionHandlerTable::copy_to(nmethod* nm) {
  assert(size_in_bytes() == nm->handler_table_size(), "size of space allocated in nmethod incorrect");
  memmove(nm->handler_table_begin(), _table, size_in_bytes());
}


HandlerTableEntry* ExceptionHandlerTable::entry_for(int catch_pco, int handler_bci, int scope_depth) const {
  HandlerTableEntry* t = subtable_for(catch_pco);
  if (t != NULL) {
    int l = t->len();
    while (l-- > 0) {
      t++;
      if (t->bci() == handler_bci && t->scope_depth() == scope_depth) return t;
    }
  }
  return NULL;
}


void ExceptionHandlerTable::print_subtable(HandlerTableEntry* t) const {
  int l = t->len();
  tty->print_cr("catch_pco = %d (%d entries)", t->pco(), l);
  while (l-- > 0) {
    t++;
    tty->print_cr("  bci %d at scope depth %d -> pco %d", t->bci(), t->scope_depth(), t->pco());
  }
}


void ExceptionHandlerTable::print() const {
  tty->print_cr("ExceptionHandlerTable (size = %d bytes)", size_in_bytes());
  int i = 0;
  while (i < _length) {
    HandlerTableEntry* t = _table + i;
    print_subtable(t);
    // advance to next subtable
    i += t->len() + 1; // +1 for header
  }
}

void ExceptionHandlerTable::print_subtable_for(int catch_pco) const {
  HandlerTableEntry* subtable = subtable_for(catch_pco);

  if( subtable != NULL ) { print_subtable( subtable ); }
}

// ----------------------------------------------------------------------------
// 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>.
void ImplicitExceptionTable::set_size( uint size ) {
  _size = size;
  _data = NEW_RESOURCE_ARRAY(implicit_null_entry, (size*2));
  _len = 0;
}

void ImplicitExceptionTable::append( uint exec_off, uint cont_off ) {
  assert( (sizeof(implicit_null_entry) >= 4) || (exec_off < 65535), "" );
  assert( (sizeof(implicit_null_entry) >= 4) || (cont_off < 65535), "" );
  uint l = len();
  if (l == _size) {
    uint old_size_in_elements = _size*2;
    if (_size == 0) _size = 4;
    _size *= 2;
    uint new_size_in_elements = _size*2;
    _data = REALLOC_RESOURCE_ARRAY(uint, _data, old_size_in_elements, new_size_in_elements);
  }
  *(adr(l)  ) = exec_off;
  *(adr(l)+1) = cont_off;
  _len = l+1;
};

uint ImplicitExceptionTable::at( uint exec_off ) const {
  uint l = len();
  for( uint i=0; i<l; i++ )
    if( *adr(i) == exec_off )
      return *(adr(i)+1);
  return 0;                     // Failed to find any execption offset
}

void ImplicitExceptionTable::print(address base) const {
  tty->print("{");
  for( uint i=0; i<len(); i++ )
    tty->print("< "INTPTR_FORMAT", "INTPTR_FORMAT" > ",base + *adr(i), base + *(adr(i)+1));
  tty->print_cr("}");
}

ImplicitExceptionTable::ImplicitExceptionTable(const nmethod* nm) {
  if (nm->nul_chk_table_size() == 0) {
    _len = 0;
    _data = NULL;
  } else {
    // the first word is the length if non-zero, so read it out and
    // skip to the next word to get the table.
    _data  = (implicit_null_entry*)nm->nul_chk_table_begin();
    _len = _data[0];
    _data++;
  }
  _size = len();
  assert(size_in_bytes() <= nm->nul_chk_table_size(), "size of space allocated in nmethod incorrect");
}

void ImplicitExceptionTable::copy_to( nmethod* nm ) {
  assert(size_in_bytes() <= nm->nul_chk_table_size(), "size of space allocated in nmethod incorrect");
  if (len() != 0) {
    implicit_null_entry* nmdata = (implicit_null_entry*)nm->nul_chk_table_begin();
    // store the length in the first uint
    nmdata[0] = _len;
    nmdata++;
    // copy the table after the length
    memmove( nmdata, _data, 2 * len() * sizeof(implicit_null_entry));
  } else {
    // zero length table takes zero bytes
    assert(size_in_bytes() == 0, "bad size");
    assert(nm->nul_chk_table_size() == 0, "bad size");
  }
}

void ImplicitExceptionTable::verify(nmethod *nm) const {
  for (uint i = 0; i < len(); i++) {
     if ((*adr(i) > (unsigned int)nm->insts_size()) ||
         (*(adr(i)+1) > (unsigned int)nm->insts_size()))
       fatal(err_msg("Invalid offset in ImplicitExceptionTable at " PTR_FORMAT, _data));
  }
}