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a64b06ec83
Issue https://dart-review.googlesource.com/c/sdk/+/115701 Change-Id: Ib579f0bbc8d694aec74afd837217316a10baf910 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/115707 Commit-Queue: Martin Kustermann <kustermann@google.com> Reviewed-by: Ryan Macnak <rmacnak@google.com> Reviewed-by: Daco Harkes <dacoharkes@google.com>
33 lines
1 KiB
C++
33 lines
1 KiB
C++
// Copyright (c) 2018, the Dart project authors. Please see the AUTHORS file
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// for details. All rights reserved. Use of this source code is governed by a
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// BSD-style license that can be found in the LICENSE file.
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#ifndef RUNTIME_VM_HASH_H_
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#define RUNTIME_VM_HASH_H_
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#include "platform/globals.h"
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namespace dart {
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inline uint32_t CombineHashes(uint32_t hash, uint32_t other_hash) {
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hash += other_hash;
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hash += hash << 10;
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hash ^= hash >> 6; // Logical shift, unsigned hash.
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return hash;
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}
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inline uint32_t FinalizeHash(uint32_t hash, intptr_t hashbits) {
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hash += hash << 3;
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hash ^= hash >> 11; // Logical shift, unsigned hash.
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hash += hash << 15;
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// FinalizeHash gets called with values for hashbits that are bigger than 31
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// (like kBitsPerWord - 1). Therefore we are careful to use a type
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// (uintptr_t) big enough to avoid undefined behavior with the left shift.
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hash &= (static_cast<uintptr_t>(1) << hashbits) - 1;
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return (hash == 0) ? 1 : hash;
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}
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} // namespace dart
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#endif // RUNTIME_VM_HASH_H_
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