+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 : uintptr_t {
+ /// PointerBitMask - The bits that come from the pointer.
+ PointerBitMask =
+ ~(uintptr_t)(((intptr_t)1 << PtrTraits::NumLowBitsAvailable) - 1),
+
+ /// 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)(((intptr_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) {
+ intptr_t IntWord = static_cast<intptr_t>(Int);
+ assert((IntWord & ~IntMask) == 0 && "Integer too large for field");
+
+ // Preserve all bits other than the ones we are updating.
+ return (OrigValue & ~ShiftedIntMask) | IntWord << IntShift;
+ }
+};
+