6024e5c395
clang 20.0.0 (based on r547379) from build 12806354. Bug: http://b/379133546 Test: N/A Change-Id: I2eb8938af55d809de674be63cb30cf27e801862b Upstream-Commit: ad834e67b1105d15ef907f6255d4c96e8e733f57
72 lines
2.5 KiB
C++
72 lines
2.5 KiB
C++
//===- DenseMapInfoVariant.h - Type traits for DenseMap<variant> *- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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///
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/// \file
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/// This file defines DenseMapInfo traits for DenseMap<std::variant<Ts...>>.
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///
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_ADT_DENSEMAPINFOVARIANT_H
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#define LLVM_ADT_DENSEMAPINFOVARIANT_H
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#include "llvm/ADT/DenseMapInfo.h"
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#include <utility>
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#include <variant>
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namespace llvm {
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// Provide DenseMapInfo for variants whose all alternatives have DenseMapInfo.
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template <typename... Ts> struct DenseMapInfo<std::variant<Ts...>> {
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using Variant = std::variant<Ts...>;
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using FirstT = std::variant_alternative_t<0, Variant>;
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static inline Variant getEmptyKey() {
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return Variant(std::in_place_index<0>, DenseMapInfo<FirstT>::getEmptyKey());
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}
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static inline Variant getTombstoneKey() {
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return Variant(std::in_place_index<0>,
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DenseMapInfo<FirstT>::getTombstoneKey());
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}
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static unsigned getHashValue(const Variant &Val) {
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return std::visit(
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[&Val](auto &&Alternative) {
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using T = std::decay_t<decltype(Alternative)>;
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// Include index in hash to make sure same value as different
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// alternatives don't collide.
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return DenseMapInfo<std::pair<size_t, T>>::getHashValuePiecewise(
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Val.index(), Alternative);
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},
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Val);
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}
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static bool isEqual(const Variant &LHS, const Variant &RHS) {
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if (LHS.index() != RHS.index())
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return false;
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if (LHS.valueless_by_exception())
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return true;
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// We want to dispatch to DenseMapInfo<T>::isEqual(LHS.get(I), RHS.get(I))
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// We know the types are the same, but std::visit(V, LHS, RHS) doesn't.
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// We erase the type held in LHS to void*, and dispatch over RHS.
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const void *ErasedLHS =
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std::visit([](const auto &LHS) -> const void * { return &LHS; }, LHS);
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return std::visit(
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[&](const auto &RHS) -> bool {
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using T = std::remove_cv_t<std::remove_reference_t<decltype(RHS)>>;
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return DenseMapInfo<T>::isEqual(*static_cast<const T *>(ErasedLHS),
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RHS);
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},
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RHS);
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}
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};
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} // end namespace llvm
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#endif // LLVM_ADT_DENSEMAPINFOVARIANT_H
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