/*

 * Copyright (c) 2019, 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 "aot/aotLoader.hpp"

#include "logging/log.hpp"

#include "logging/logStream.hpp"

#include "memory/memRegion.hpp"

#include "memory/universe.hpp"

#include "oops/compressedOops.hpp"

#include "gc/shared/collectedHeap.hpp"

#include "runtime/globals.hpp"

// For UseCompressedOops.

NarrowPtrStruct CompressedOops::_narrow_oop = { NULL, 0, true };

address CompressedOops::_narrow_ptrs_base;

// Choose the heap base address and oop encoding mode

// when compressed oops are used:

// Unscaled  - Use 32-bits oops without encoding when

//     NarrowOopHeapBaseMin + heap_size < 4Gb

// ZeroBased - Use zero based compressed oops with encoding when

//     NarrowOopHeapBaseMin + heap_size < 32Gb

// HeapBased - Use compressed oops with heap base + encoding.

void CompressedOops::initialize() {

#ifdef _LP64

  if (UseCompressedOops) {

    // Subtract a page because something can get allocated at heap base.

    // This also makes implicit null checking work, because the

    // memory+1 page below heap_base needs to cause a signal.

    // See needs_explicit_null_check.

    // Only set the heap base for compressed oops because it indicates

    // compressed oops for pstack code.

    if ((uint64_t)Universe::heap()->reserved_region().end() > UnscaledOopHeapMax) {

      // Didn't reserve heap below 4Gb.  Must shift.

      set_shift(LogMinObjAlignmentInBytes);

    }

    if ((uint64_t)Universe::heap()->reserved_region().end() <= OopEncodingHeapMax) {

      // Did reserve heap below 32Gb. Can use base == 0;

      set_base(0);

    }

    AOTLoader::set_narrow_oop_shift();

    set_ptrs_base(base());

    LogTarget(Info, gc, heap, coops) lt;

    if (lt.is_enabled()) {

      ResourceMark rm;

      LogStream ls(lt);

      print_mode(&ls);

    }

    // Tell tests in which mode we run.

    Arguments::PropertyList_add(new SystemProperty("java.vm.compressedOopsMode",

                                                   mode_to_string(mode()),

                                                   false));

  }

  // base() is one page below the heap.

  assert((intptr_t)base() <= (intptr_t)(Universe::heap()->base() - os::vm_page_size()) ||

         base() == NULL, "invalid value");

  assert(shift() == LogMinObjAlignmentInBytes ||

         shift() == 0, "invalid value");

#endif

}

void CompressedOops::set_base(address base) {

  assert(UseCompressedOops, "no compressed oops?");

  _narrow_oop._base    = base;

}

void CompressedOops::set_shift(int shift) {

  _narrow_oop._shift   = shift;

}

void CompressedOops::set_use_implicit_null_checks(bool use) {

  assert(UseCompressedOops, "no compressed ptrs?");

  _narrow_oop._use_implicit_null_checks   = use;

}

void CompressedOops::set_ptrs_base(address addr) {

  _narrow_ptrs_base = addr;

}

CompressedOops::Mode CompressedOops::mode() {

  if (base_disjoint()) {

    return DisjointBaseNarrowOop;

  }

  if (base() != 0) {

    return HeapBasedNarrowOop;

  }

  if (shift() != 0) {

    return ZeroBasedNarrowOop;

  }

  return UnscaledNarrowOop;

}

const char* CompressedOops::mode_to_string(Mode mode) {

  switch (mode) {

    case UnscaledNarrowOop:

      return "32-bit";

    case ZeroBasedNarrowOop:

      return "Zero based";

    case DisjointBaseNarrowOop:

      return "Non-zero disjoint base";

    case HeapBasedNarrowOop:

      return "Non-zero based";

    default:

      ShouldNotReachHere();

      return "";

  }

}

// Test whether bits of addr and possible offsets into the heap overlap.

bool CompressedOops::is_disjoint_heap_base_address(address addr) {

  return (((uint64_t)(intptr_t)addr) &

          (((uint64_t)UCONST64(0xFFFFffffFFFFffff)) >> (32-LogMinObjAlignmentInBytes))) == 0;

}

// Check for disjoint base compressed oops.

bool CompressedOops::base_disjoint() {

  return _narrow_oop._base != NULL && is_disjoint_heap_base_address(_narrow_oop._base);

}

// Check for real heapbased compressed oops.

// We must subtract the base as the bits overlap.

// If we negate above function, we also get unscaled and zerobased.

bool CompressedOops::base_overlaps() {

  return _narrow_oop._base != NULL && !is_disjoint_heap_base_address(_narrow_oop._base);

}

void CompressedOops::print_mode(outputStream* st) {

  st->print("Heap address: " PTR_FORMAT ", size: " SIZE_FORMAT " MB",

            p2i(Universe::heap()->base()), Universe::heap()->reserved_region().byte_size()/M);

  st->print(", Compressed Oops mode: %s", mode_to_string(mode()));

  if (base() != 0) {

    st->print(": " PTR_FORMAT, p2i(base()));

  }

  if (shift() != 0) {

    st->print(", Oop shift amount: %d", shift());

  }

  if (!use_implicit_null_checks()) {

    st->print(", no protected page in front of the heap");

  }

  st->cr();

}

// For UseCompressedClassPointers.

NarrowPtrStruct CompressedKlassPointers::_narrow_klass = { NULL, 0, true };

// CompressedClassSpaceSize set to 1GB, but appear 3GB away from _narrow_ptrs_base during CDS dump.

uint64_t CompressedKlassPointers::_narrow_klass_range = (uint64_t(max_juint)+1);;

void CompressedKlassPointers::set_base(address base) {

  assert(UseCompressedClassPointers, "no compressed klass ptrs?");

  _narrow_klass._base   = base;

}

void CompressedKlassPointers::set_shift(int shift)       {

  assert(shift == 0 || shift == LogKlassAlignmentInBytes, "invalid shift for klass ptrs");

  _narrow_klass._shift   = shift;

}

void CompressedKlassPointers::set_range(uint64_t range) {

  assert(UseCompressedClassPointers, "no compressed klass ptrs?");

  _narrow_klass_range = range;

}