[libbase][adt] Add pointer utility typesHEADmaster

1 files changed, 301 insertions, 0 deletions

diff --git a/libbase/include/core/adt/PointerIntPair.h b/libbase/include/core/adt/PointerIntPair.h
new file mode 100644
index 0000000..6a7f5db
--- /dev/null
+++ b/libbase/include/core/adt/PointerIntPair.h
@@ -0,0 +1,301 @@
+/*
+ RCC-Project
+
+ Copyright (C) 2026 Richard Qin
+
+ This file is part of RCC-Project.
+
+ RCC-Project is free software; you can redistribute it and/or modify it under
+ the terms of the GNU General Public License as published by the Free
+ Software Foundation; either version 3 of the License, or (at your option) any
+ later version.
+
+ RCC-Project 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 for more details.
+
+ You should have received a copy of the GNU General Public License along with
+ RCC-Project; see the file COPYING. If not see
+ <http://www.gnu.org/licenses/>.
+*/
+
+//===- core/adt/PointerIntPair.h - Pair for pointer and int -----*- 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
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file defines the PointerIntPair class.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LIBBASE_ADT_POINTERINTPAIR_H
+#define LIBBASE_ADT_POINTERINTPAIR_H
+
+#include "core/compiler/Compiler.h"
+#include "core/adt/PointerLikeTypeTraits.h"
+#include <cassert>
+#include <cstdint>
+#include <cstring>
+#include <limits>
+#include <type_traits>
+
+namespace libbase {
+
+namespace detail {
+template <typename Ptr> struct PunnedPointer {
+  static_assert(sizeof(Ptr) == sizeof(intptr_t), "");
+
+  // Asserts that allow us to let the compiler implement the destructor and
+  // copy/move constructors
+  static_assert(std::is_trivially_destructible<Ptr>::value, "");
+  static_assert(std::is_trivially_copy_constructible<Ptr>::value, "");
+  static_assert(std::is_trivially_move_constructible<Ptr>::value, "");
+
+  explicit constexpr PunnedPointer(intptr_t i = 0) { *this = i; }
+
+  constexpr intptr_t asInt() const {
+    intptr_t R = 0;
+    std::memcpy(&R, Data, sizeof(R));
+    return R;
+  }
+
+  constexpr operator intptr_t() const { return asInt(); }
+
+  constexpr PunnedPointer &operator=(intptr_t V) {
+    std::memcpy(Data, &V, sizeof(Data));
+    return *this;
+  }
+
+  Ptr *getPointerAddress() { return reinterpret_cast<Ptr *>(Data); }
+  const Ptr *getPointerAddress() const { return reinterpret_cast<Ptr *>(Data); }
+
+private:
+  alignas(Ptr) unsigned char Data[sizeof(Ptr)];
+};
+} // namespace detail
+
+template <typename T, typename Enable> struct DenseMapInfo;
+template <typename PointerT, unsigned IntBits, typename PtrTraits>
+struct PointerIntPairInfo;
+
+/// PointerIntPair - This class implements a pair of a pointer and small
+/// integer.  It is designed to represent this in the space required by one
+/// pointer by bitmangling the integer into the low part of the pointer.  This
+/// can only be done for small integers: typically up to 3 bits, but it depends
+/// on the number of bits available according to PointerLikeTypeTraits for the
+/// type.
+///
+/// Note that PointerIntPair always puts the IntVal part in the highest bits
+/// possible.  For example, PointerIntPair<void*, 1, bool> will put the bit for
+/// the bool into bit #2, not bit #0, which allows the low two bits to be used
+/// for something else.  For example, this allows:
+///   PointerIntPair<PointerIntPair<void*, 1, bool>, 1, bool>
+/// ... and the two bools will land in different bits.
+template <typename PointerTy, unsigned IntBits, typename IntType = unsigned,
+          typename PtrTraits = PointerLikeTypeTraits<PointerTy>,
+          typename Info = PointerIntPairInfo<PointerTy, IntBits, PtrTraits>>
+class PointerIntPair {
+  // Used by MSVC visualizer and generally helpful for debugging/visualizing.
+  using InfoTy = Info;
+  detail::PunnedPointer<PointerTy> Value;
+
+public:
+  constexpr PointerIntPair() = default;
+
+  PointerIntPair(PointerTy PtrVal, IntType IntVal) {
+    setPointerAndInt(PtrVal, IntVal);
+  }
+
+  explicit PointerIntPair(PointerTy PtrVal) { initWithPointer(PtrVal); }
+
+  PointerTy getPointer() const { return Info::getPointer(Value); }
+
+  IntType getInt() const { return (IntType)Info::getInt(Value); }
+
+  void setPointer(PointerTy PtrVal) & {
+    Value = Info::updatePointer(Value, PtrVal);
+  }
+
+  void setInt(IntType IntVal) & {
+    Value = Info::updateInt(Value, static_cast<intptr_t>(IntVal));
+  }
+
+  void initWithPointer(PointerTy PtrVal) & {
+    Value = Info::updatePointer(0, PtrVal);
+  }
+
+  void setPointerAndInt(PointerTy PtrVal, IntType IntVal) & {
+    Value = Info::updateInt(Info::updatePointer(0, PtrVal),
+                            static_cast<intptr_t>(IntVal));
+  }
+
+  PointerTy const *getAddrOfPointer() const {
+    return const_cast<PointerIntPair *>(this)->getAddrOfPointer();
+  }
+
+  PointerTy *getAddrOfPointer() {
+    assert(Value == reinterpret_cast<intptr_t>(getPointer()) &&
+           "Can only return the address if IntBits is cleared and "
+           "PtrTraits doesn't change the pointer");
+    return Value.getPointerAddress();
+  }
+
+  void *getOpaqueValue() const {
+    return reinterpret_cast<void *>(Value.asInt());
+  }
+
+  void setFromOpaqueValue(void *Val) & {
+    Value = reinterpret_cast<intptr_t>(Val);
+  }
+
+  static PointerIntPair getFromOpaqueValue(void *V) {
+    PointerIntPair P;
+    P.setFromOpaqueValue(V);
+    return P;
+  }
+
+  // Allow PointerIntPairs to be created from const void * if and only if the
+  // pointer type could be created from a const void *.
+  static PointerIntPair getFromOpaqueValue(const void *V) {
+    (void)PtrTraits::getFromVoidPointer(V);
+    return getFromOpaqueValue(const_cast<void *>(V));
+  }
+
+  bool operator==(const PointerIntPair &RHS) const {
+    return Value == RHS.Value;
+  }
+
+  bool operator!=(const PointerIntPair &RHS) const {
+    return Value != RHS.Value;
+  }
+
+  bool operator<(const PointerIntPair &RHS) const { return Value < RHS.Value; }
+  bool operator>(const PointerIntPair &RHS) const { return Value > RHS.Value; }
+
+  bool operator<=(const PointerIntPair &RHS) const {
+    return Value <= RHS.Value;
+  }
+
+  bool operator>=(const PointerIntPair &RHS) const {
+    return Value >= RHS.Value;
+  }
+};
+
+template <typename PointerT, unsigned IntBits, typename PtrTraits>
+struct PointerIntPairInfo {
+  static_assert(PtrTraits::NumLowBitsAvailable <
+                    std::numeric_limits<uintptr_t>::digits,
+                "cannot use a pointer type that has all bits free");
+  static_assert(IntBits <= PtrTraits::NumLowBitsAvailable,
+                "PointerIntPair with integer size too large for pointer");
+  enum MaskAndShiftConstants : uintptr_t {
+    /// PointerBitMask - The bits that come from the pointer.
+    PointerBitMask = (~(uintptr_t)0) << PtrTraits::NumLowBitsAvailable,
+
+    /// IntShift - The number of low bits that we reserve for other uses, and
+    /// keep zero.
+    IntShift = (uintptr_t)PtrTraits::NumLowBitsAvailable - IntBits,
+
+    /// IntMask - This is the unshifted mask for valid bits of the int type.
+    IntMask = ((uintptr_t)1 << IntBits) - 1,
+
+    // ShiftedIntMask - This is the bits for the integer shifted in place.
+    ShiftedIntMask = (uintptr_t)(IntMask << IntShift)
+  };
+
+  static PointerT getPointer(intptr_t Value) {
+    return PtrTraits::getFromVoidPointer(
+        reinterpret_cast<void *>(Value & PointerBitMask));
+  }
+
+  static intptr_t getInt(intptr_t Value) {
+    return (Value >> IntShift) & IntMask;
+  }
+
+  static intptr_t updatePointer(intptr_t OrigValue, PointerT Ptr) {
+    intptr_t PtrWord =
+        reinterpret_cast<intptr_t>(PtrTraits::getAsVoidPointer(Ptr));
+    assert((PtrWord & ~PointerBitMask) == 0 &&
+           "Pointer is not sufficiently aligned");
+    // Preserve all low bits, just update the pointer.
+    return PtrWord | (OrigValue & ~PointerBitMask);
+  }
+
+  static intptr_t updateInt(intptr_t OrigValue, intptr_t Int) {
+    assert((Int & ~IntMask) == 0 && "Integer too large for field");
+
+    // Preserve all bits other than the ones we are updating.
+    return (OrigValue & ~ShiftedIntMask) | Int << IntShift;
+  }
+};
+
+// Provide specialization of DenseMapInfo for PointerIntPair.
+template <typename PointerTy, unsigned IntBits, typename IntType>
+struct DenseMapInfo<PointerIntPair<PointerTy, IntBits, IntType>, void> {
+  using Ty = PointerIntPair<PointerTy, IntBits, IntType>;
+
+  static unsigned getHashValue(Ty V) {
+    uintptr_t IV = reinterpret_cast<uintptr_t>(V.getOpaqueValue());
+    return unsigned(IV) ^ unsigned(IV >> 9);
+  }
+
+  static bool isEqual(const Ty &LHS, const Ty &RHS) { return LHS == RHS; }
+};
+
+// Teach SmallPtrSet that PointerIntPair is "basically a pointer".
+template <typename PointerTy, unsigned IntBits, typename IntType,
+          typename PtrTraits>
+struct PointerLikeTypeTraits<
+    PointerIntPair<PointerTy, IntBits, IntType, PtrTraits>> {
+  static inline void *
+  getAsVoidPointer(const PointerIntPair<PointerTy, IntBits, IntType> &P) {
+    return P.getOpaqueValue();
+  }
+
+  static inline PointerIntPair<PointerTy, IntBits, IntType>
+  getFromVoidPointer(void *P) {
+    return PointerIntPair<PointerTy, IntBits, IntType>::getFromOpaqueValue(P);
+  }
+
+  static inline PointerIntPair<PointerTy, IntBits, IntType>
+  getFromVoidPointer(const void *P) {
+    return PointerIntPair<PointerTy, IntBits, IntType>::getFromOpaqueValue(P);
+  }
+
+  static constexpr int NumLowBitsAvailable =
+      PtrTraits::NumLowBitsAvailable - IntBits;
+};
+
+// Allow structured bindings on PointerIntPair.
+template <std::size_t I, typename PointerTy, unsigned IntBits, typename IntType,
+          typename PtrTraits, typename Info>
+decltype(auto)
+get(const PointerIntPair<PointerTy, IntBits, IntType, PtrTraits, Info> &Pair) {
+  static_assert(I < 2);
+  if constexpr (I == 0)
+    return Pair.getPointer();
+  else
+    return Pair.getInt();
+}
+
+} // end namespace libbase
+
+namespace std {
+template <typename PointerTy, unsigned IntBits, typename IntType,
+          typename PtrTraits, typename Info>
+struct tuple_size<
+    libbase::PointerIntPair<PointerTy, IntBits, IntType, PtrTraits, Info>>
+    : std::integral_constant<std::size_t, 2> {};
+
+template <std::size_t I, typename PointerTy, unsigned IntBits, typename IntType,
+          typename PtrTraits, typename Info>
+struct tuple_element<
+    I, libbase::PointerIntPair<PointerTy, IntBits, IntType, PtrTraits, Info>>
+    : std::conditional<I == 0, PointerTy, IntType> {};
+} // namespace std
+
+#endif // LIBBASE_ADT_POINTERINTPAIR_H