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/*
* Copyright (c) 2013, 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_GC_IMPLEMENTATION_G1_G1BIASEDARRAY_HPP
#define SHARE_VM_GC_IMPLEMENTATION_G1_G1BIASEDARRAY_HPP
#include "memory/allocation.hpp"
#include "utilities/debug.hpp"
// Implements the common base functionality for arrays that contain provisions
// for accessing its elements using a biased index.
// The element type is defined by the instantiating the template.
class G1BiasedMappedArrayBase VALUE_OBJ_CLASS_SPEC {
friend class VMStructs;
public:
typedef size_t idx_t;
protected:
address _base; // the real base address
size_t _length; // the length of the array
address _biased_base; // base address biased by "bias" elements
size_t _bias; // the bias, i.e. the offset biased_base is located to the right in elements
uint _shift_by; // the amount of bits to shift right when mapping to an index of the array.
protected:
G1BiasedMappedArrayBase() : _base(NULL), _length(0), _biased_base(NULL),
_bias(0), _shift_by(0) { }
// Allocate a new array, generic version.
static address create_new_base_array(size_t length, size_t elem_size);
// Initialize the members of this class. The biased start address of this array
// is the bias (in elements) multiplied by the element size.
void initialize_base(address base, size_t length, size_t bias, size_t elem_size, uint shift_by) {
assert(base != NULL, "just checking");
assert(length > 0, "just checking");
assert(shift_by < sizeof(uintptr_t) * 8, err_msg("Shifting by %zd, larger than word size?", shift_by));
_base = base;
_length = length;
_biased_base = base - (bias * elem_size);
_bias = bias;
_shift_by = shift_by;
}
// Allocate and initialize this array to cover the heap addresses in the range
// of [bottom, end).
void initialize(HeapWord* bottom, HeapWord* end, size_t target_elem_size_in_bytes, size_t mapping_granularity_in_bytes) {
assert(mapping_granularity_in_bytes > 0, "just checking");
assert(is_power_of_2(mapping_granularity_in_bytes),
err_msg("mapping granularity must be power of 2, is %zd", mapping_granularity_in_bytes));
assert((uintptr_t)bottom % mapping_granularity_in_bytes == 0,
err_msg("bottom mapping area address must be a multiple of mapping granularity %zd, is "PTR_FORMAT,
mapping_granularity_in_bytes, bottom));
assert((uintptr_t)end % mapping_granularity_in_bytes == 0,
err_msg("end mapping area address must be a multiple of mapping granularity %zd, is "PTR_FORMAT,
mapping_granularity_in_bytes, end));
size_t num_target_elems = (end - bottom) / (mapping_granularity_in_bytes / HeapWordSize);
idx_t bias = (uintptr_t)bottom / mapping_granularity_in_bytes;
address base = create_new_base_array(num_target_elems, target_elem_size_in_bytes);
initialize_base(base, num_target_elems, bias, target_elem_size_in_bytes, log2_intptr(mapping_granularity_in_bytes));
}
size_t bias() const { return _bias; }
uint shift_by() const { return _shift_by; }
void verify_index(idx_t index) const PRODUCT_RETURN;
void verify_biased_index(idx_t biased_index) const PRODUCT_RETURN;
void verify_biased_index_inclusive_end(idx_t biased_index) const PRODUCT_RETURN;
public:
// Return the length of the array in elements.
size_t length() const { return _length; }
};
// Array that provides biased access and mapping from (valid) addresses in the
// heap into this array.
template<class T>
class G1BiasedMappedArray : public G1BiasedMappedArrayBase {
public:
typedef G1BiasedMappedArrayBase::idx_t idx_t;
T* base() const { return (T*)G1BiasedMappedArrayBase::_base; }
// Return the element of the given array at the given index. Assume
// the index is valid. This is a convenience method that does sanity
// checking on the index.
T get_by_index(idx_t index) const {
verify_index(index);
return this->base()[index];
}
// Set the element of the given array at the given index to the
// given value. Assume the index is valid. This is a convenience
// method that does sanity checking on the index.
void set_by_index(idx_t index, T value) {
verify_index(index);
this->base()[index] = value;
}
// The raw biased base pointer.
T* biased_base() const { return (T*)G1BiasedMappedArrayBase::_biased_base; }
// Return the element of the given array that covers the given word in the
// heap. Assumes the index is valid.
T get_by_address(HeapWord* value) const {
idx_t biased_index = ((uintptr_t)value) >> this->shift_by();
this->verify_biased_index(biased_index);
return biased_base()[biased_index];
}
// Set the value of the array entry that corresponds to the given array.
void set_by_address(HeapWord * address, T value) {
idx_t biased_index = ((uintptr_t)address) >> this->shift_by();
this->verify_biased_index(biased_index);
biased_base()[biased_index] = value;
}
protected:
// Returns the address of the element the given address maps to
T* address_mapped_to(HeapWord* address) {
idx_t biased_index = ((uintptr_t)address) >> this->shift_by();
this->verify_biased_index_inclusive_end(biased_index);
return biased_base() + biased_index;
}
public:
// Return the smallest address (inclusive) in the heap that this array covers.
HeapWord* bottom_address_mapped() const {
return (HeapWord*) ((uintptr_t)this->bias() << this->shift_by());
}
// Return the highest address (exclusive) in the heap that this array covers.
HeapWord* end_address_mapped() const {
return (HeapWord*) ((uintptr_t)(this->bias() + this->length()) << this->shift_by());
}
protected:
virtual T default_value() const = 0;
// Set all elements of the given array to the given value.
void clear() {
T value = default_value();
for (idx_t i = 0; i < length(); i++) {
set_by_index(i, value);
}
}
public:
G1BiasedMappedArray() {}
// Allocate and initialize this array to cover the heap addresses in the range
// of [bottom, end).
void initialize(HeapWord* bottom, HeapWord* end, size_t mapping_granularity) {
G1BiasedMappedArrayBase::initialize(bottom, end, sizeof(T), mapping_granularity);
this->clear();
}
};
#endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1BIASEDARRAY_HPP
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