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Diffstat (limited to 'contrib/llvm-project/llvm/include/llvm/ADT/Waymarking.h')
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1 files changed, 0 insertions, 322 deletions
diff --git a/contrib/llvm-project/llvm/include/llvm/ADT/Waymarking.h b/contrib/llvm-project/llvm/include/llvm/ADT/Waymarking.h deleted file mode 100644 index 2efbc6f05495..000000000000 --- a/contrib/llvm-project/llvm/include/llvm/ADT/Waymarking.h +++ /dev/null @@ -1,322 +0,0 @@ -//===- Waymarking.h - Array waymarking algorithm ----------------*- C++ -*-===// -// -// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. -// See https://llvm.org/LICENSE.txt for license information. -// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception -// -//===----------------------------------------------------------------------===// -// -// Utility to backtrace an array's head, from a pointer into it. For the -// backtrace to work, we use "Waymarks", which are special tags embedded into -// the array's elements. -// -// A Tag of n-bits (in size) is composed as follows: -// -// bits: | n-1 | n-2 ... 0 | -// .---------.------------------------------------. -// |Stop Mask|(2^(n-1))-ary numeric system - digit| -// '---------'------------------------------------' -// -// Backtracing is done as follows: -// Walk back (starting from a given pointer to an element into the array), until -// a tag with a "Stop Mask" is reached. Then start calculating the "Offset" from -// the array's head, by picking up digits along the way, until another stop is -// reached. The "Offset" is then subtracted from the current pointer, and the -// result is the array's head. -// A special case - if we first encounter a Tag with a Stop and a zero digit, -// then this is already the head. -// -// For example: -// In case of 2 bits: -// -// Tags: -// x0 - binary digit 0 -// x1 - binary digit 1 -// 1x - stop and calculate (s) -// -// Array: -// .---.---.---.---.---.---.---.---.---.---.---.---.---.---.---.---. -// head -> |s0 |s1 | 0 |s1 | 0 | 0 |s1 | 1 | 1 |s1 | 0 | 1 | 0 |s1 | 0 | 1 | -// '---'---'---'---'---'---'---'---'---'---'---'---'---'---'---'---' -// |-1 |-2 |-4 |-7 |-10 |-14 -// <_ | | | | | | -// <_____ | | | | | -// <_____________ | | | | -// <_________________________ | | | -// <_____________________________________ | | -// <_____________________________________________________ | -// -// -// In case of 3 bits: -// -// Tags: -// x00 - quaternary digit 0 -// x01 - quaternary digit 1 -// x10 - quaternary digit 2 -// x11 - quaternary digit 3 -// 1xy - stop and calculate (s) -// -// Array: -// .---.---.---.---.---.---.---.---.---.---.---.---.---.---.---.---. -// head -> |s0 |s1 |s2 |s3 | 0 |s1 | 2 |s1 | 0 |s2 | 2 |s2 | 0 |s3 | 2 |s3 | -// '---'---'---'---'---'---'---'---'---'---'---'---'---'---'---'---' -// |-1 |-2 |-3 |-4 |-6 |-8 |-10 |-12 |-14 |-16 -// <_ | | | | | | | | | | -// <_____ | | | | | | | | | -// <_________ | | | | | | | | -// <_____________ | | | | | | | -// <_____________________ | | | | | | -// <_____________________________ | | | | | -// <_____________________________________ | | | | -// <_____________________________________________ | | | -// <_____________________________________________________ | | -// <_____________________________________________________________ | -// -// -// The API introduce 2 functions: -// 1. fillWaymarks -// 2. followWaymarks -// -// Example: -// int N = 10; -// int M = 5; -// int **A = new int *[N + M]; // Define the array. -// for (int I = 0; I < N + M; ++I) -// A[I] = new int(I); -// -// fillWaymarks(A, A + N); // Set the waymarks for the first N elements -// // of the array. -// // Note that it must be done AFTER we fill -// // the array's elements. -// -// ... // Elements which are not in the range -// // [A, A+N) will not be marked, and we won't -// // be able to call followWaymarks on them. -// -// ... // Elements which will be changed after the -// // call to fillWaymarks, will have to be -// // retagged. -// -// fillWaymarks(A + N, A + N + M, N); // Set the waymarks of the remaining M -// // elements. -// ... -// int **It = A + N + 1; -// int **B = followWaymarks(It); // Find the head of the array containing It. -// assert(B == A); -// -//===----------------------------------------------------------------------===// - -#ifndef LLVM_ADT_WAYMARKING_H -#define LLVM_ADT_WAYMARKING_H - -#include "llvm/ADT/STLExtras.h" -#include "llvm/Support/PointerLikeTypeTraits.h" - -namespace llvm { - -namespace detail { - -template <unsigned NumBits> struct WaymarkingTraits { - enum : unsigned { - // The number of bits of a Waymarking Tag. - NUM_BITS = NumBits, - - // A Tag is composed from a Mark and a Stop mask. - MARK_SIZE = NUM_BITS - 1, - STOP_MASK = (1 << MARK_SIZE), - MARK_MASK = (STOP_MASK - 1), - TAG_MASK = (MARK_MASK | STOP_MASK), - - // The number of pre-computed tags (for fast fill). - NUM_STATIC_TAGS = 32 - }; - -private: - // Add a new tag, calculated from Count and Stop, to the Vals pack, while - // continuing recursively to decrease Len down to 0. - template <unsigned Len, bool Stop, unsigned Count, uint8_t... Vals> - struct AddTag; - - // Delegate to the specialized AddTag according to the need of a Stop mask. - template <unsigned Len, unsigned Count, uint8_t... Vals> struct GenTag { - typedef - typename AddTag<Len, (Count <= MARK_MASK), Count, Vals...>::Xdata Xdata; - }; - - // Start adding tags while calculating the next Count, which is actually the - // number of already calculated tags (equivalent to the position in the - // array). - template <unsigned Len, uint8_t... Vals> struct GenOffset { - typedef typename GenTag<Len, sizeof...(Vals), Vals...>::Xdata Xdata; - }; - - // Add the tag and remove it from Count. - template <unsigned Len, unsigned Count, uint8_t... Vals> - struct AddTag<Len, false, Count, Vals...> { - typedef typename GenTag<Len - 1, (Count >> MARK_SIZE), Vals..., - Count & MARK_MASK>::Xdata Xdata; - }; - - // We have reached the end of this Count, so start with a new Count. - template <unsigned Len, unsigned Count, uint8_t... Vals> - struct AddTag<Len, true, Count, Vals...> { - typedef typename GenOffset<Len - 1, Vals..., - (Count & MARK_MASK) | STOP_MASK>::Xdata Xdata; - }; - - template <unsigned Count, uint8_t... Vals> struct TagsData { - // The remaining number for calculating the next tag, following the last one - // in Values. - static const unsigned Remain = Count; - - // The array of ordered pre-computed Tags. - static const uint8_t Values[sizeof...(Vals)]; - }; - - // Specialize the case when Len equals 0, as the recursion stop condition. - template <unsigned Count, uint8_t... Vals> - struct AddTag<0, false, Count, Vals...> { - typedef TagsData<Count, Vals...> Xdata; - }; - - template <unsigned Count, uint8_t... Vals> - struct AddTag<0, true, Count, Vals...> { - typedef TagsData<Count, Vals...> Xdata; - }; - -public: - typedef typename GenOffset<NUM_STATIC_TAGS>::Xdata Tags; -}; - -template <unsigned NumBits> -template <unsigned Count, uint8_t... Vals> -const uint8_t WaymarkingTraits<NumBits>::TagsData< - Count, Vals...>::Values[sizeof...(Vals)] = {Vals...}; - -} // end namespace detail - -/// This class is responsible for tagging (and retrieving the tag of) a given -/// element of type T. -template <class T, class WTraits = detail::WaymarkingTraits< - PointerLikeTypeTraits<T>::NumLowBitsAvailable>> -struct Waymarker { - using Traits = WTraits; - static void setWaymark(T &N, unsigned Tag) { N.setWaymark(Tag); } - static unsigned getWaymark(const T &N) { return N.getWaymark(); } -}; - -template <class T, class WTraits> struct Waymarker<T *, WTraits> { - using Traits = WTraits; - static void setWaymark(T *&N, unsigned Tag) { - reinterpret_cast<uintptr_t &>(N) |= static_cast<uintptr_t>(Tag); - } - static unsigned getWaymark(const T *N) { - return static_cast<unsigned>(reinterpret_cast<uintptr_t>(N)) & - Traits::TAG_MASK; - } -}; - -/// Sets up the waymarking algorithm's tags for a given range [Begin, End). -/// -/// \param Begin The beginning of the range to mark with tags (inclusive). -/// \param End The ending of the range to mark with tags (exclusive). -/// \param Offset The position in the supposed tags array from which to start -/// marking the given range. -template <class TIter, class Marker = Waymarker< - typename std::iterator_traits<TIter>::value_type>> -void fillWaymarks(TIter Begin, TIter End, size_t Offset = 0) { - if (Begin == End) - return; - - size_t Count = Marker::Traits::Tags::Remain; - if (Offset <= Marker::Traits::NUM_STATIC_TAGS) { - // Start by filling the pre-calculated tags, starting from the given offset. - while (Offset != Marker::Traits::NUM_STATIC_TAGS) { - Marker::setWaymark(*Begin, Marker::Traits::Tags::Values[Offset]); - - ++Offset; - ++Begin; - - if (Begin == End) - return; - } - } else { - // The given offset is larger than the number of pre-computed tags, so we - // must do it the hard way. - // Calculate the next remaining Count, as if we have filled the tags up to - // the given offset. - size_t Off = Marker::Traits::NUM_STATIC_TAGS; - do { - ++Off; - - // If the count can fit into the tag, then the counting must stop. - if (Count <= Marker::Traits::MARK_MASK) { - Count = Off; - } else - Count >>= Marker::Traits::MARK_SIZE; - } while (Off != Offset); - } - - // By now, we have the matching remaining Count for the current offset. - do { - ++Offset; - - unsigned Tag = Count & Marker::Traits::MARK_MASK; - - // If the count can fit into the tag, then the counting must stop. - if (Count <= Marker::Traits::MARK_MASK) { - Tag |= Marker::Traits::STOP_MASK; - Count = Offset; - } else - Count >>= Marker::Traits::MARK_SIZE; - - Marker::setWaymark(*Begin, Tag); - ++Begin; - } while (Begin != End); -} - -/// Sets up the waymarking algorithm's tags for a given range. -/// -/// \param Range The range to mark with tags. -/// \param Offset The position in the supposed tags array from which to start -/// marking the given range. -template <typename R, class Marker = Waymarker<typename std::remove_reference< - decltype(*std::begin(std::declval<R &>()))>::type>> -void fillWaymarks(R &&Range, size_t Offset = 0) { - return fillWaymarks<decltype(std::begin(std::declval<R &>())), Marker>( - adl_begin(Range), adl_end(Range), Offset); -} - -/// Retrieves the element marked with tag of only STOP_MASK, by following the -/// waymarks. This is the first element in a range passed to a previous call to -/// \c fillWaymarks with \c Offset 0. -/// -/// For the trivial usage of calling \c fillWaymarks(Array), and \I is an -/// iterator inside \c Array, this function retrieves the head of \c Array, by -/// following the waymarks. -/// -/// \param I The iterator into an array which was marked by the waymarking tags -/// (by a previous call to \c fillWaymarks). -template <class TIter, class Marker = Waymarker< - typename std::iterator_traits<TIter>::value_type>> -TIter followWaymarks(TIter I) { - unsigned Tag; - do - Tag = Marker::getWaymark(*I--); - while (!(Tag & Marker::Traits::STOP_MASK)); - - // Special case for the first Use. - if (Tag != Marker::Traits::STOP_MASK) { - ptrdiff_t Offset = Tag & Marker::Traits::MARK_MASK; - while (!((Tag = Marker::getWaymark(*I)) & Marker::Traits::STOP_MASK)) { - Offset = (Offset << Marker::Traits::MARK_SIZE) + Tag; - --I; - } - I -= Offset; - } - return ++I; -} - -} // end namespace llvm - -#endif // LLVM_ADT_WAYMARKING_H |