Implement P0513R0 - "Poisoning the Hash"
Summary:
Exactly what the title says.
This patch also adds a `std::hash<nullptr_t>` specialization in C++17, but it was not added by this paper and I can't find the actual paper that adds it.
See http://wg21.link/P0513R0 for more info.
If there are no comments in the next couple of days I'll commit this
Reviewers: mclow.lists, K-ballo, EricWF
Reviewed By: EricWF
Subscribers: cfe-commits
Differential Revision: https://reviews.llvm.org/D28938
llvm-svn: 292684
diff --git a/libcxx/include/utility b/libcxx/include/utility
index cc0646c..c230511 100644
--- a/libcxx/include/utility
+++ b/libcxx/include/utility
@@ -198,6 +198,9 @@
#include <__tuple>
#include <type_traits>
#include <initializer_list>
+#include <cstddef>
+#include <cstring>
+#include <cstdint>
#include <__debug>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
@@ -930,6 +933,643 @@
#endif // _LIBCPP_STD_VER > 14
+template <class _Arg, class _Result>
+struct _LIBCPP_TEMPLATE_VIS unary_function
+{
+ typedef _Arg argument_type;
+ typedef _Result result_type;
+};
+
+template <class _Size>
+inline _LIBCPP_INLINE_VISIBILITY
+_Size
+__loadword(const void* __p)
+{
+ _Size __r;
+ std::memcpy(&__r, __p, sizeof(__r));
+ return __r;
+}
+
+// We use murmur2 when size_t is 32 bits, and cityhash64 when size_t
+// is 64 bits. This is because cityhash64 uses 64bit x 64bit
+// multiplication, which can be very slow on 32-bit systems.
+template <class _Size, size_t = sizeof(_Size)*__CHAR_BIT__>
+struct __murmur2_or_cityhash;
+
+template <class _Size>
+struct __murmur2_or_cityhash<_Size, 32>
+{
+ _Size operator()(const void* __key, _Size __len);
+};
+
+// murmur2
+template <class _Size>
+_Size
+__murmur2_or_cityhash<_Size, 32>::operator()(const void* __key, _Size __len) _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK
+{
+ const _Size __m = 0x5bd1e995;
+ const _Size __r = 24;
+ _Size __h = __len;
+ const unsigned char* __data = static_cast<const unsigned char*>(__key);
+ for (; __len >= 4; __data += 4, __len -= 4)
+ {
+ _Size __k = __loadword<_Size>(__data);
+ __k *= __m;
+ __k ^= __k >> __r;
+ __k *= __m;
+ __h *= __m;
+ __h ^= __k;
+ }
+ switch (__len)
+ {
+ case 3:
+ __h ^= __data[2] << 16;
+ case 2:
+ __h ^= __data[1] << 8;
+ case 1:
+ __h ^= __data[0];
+ __h *= __m;
+ }
+ __h ^= __h >> 13;
+ __h *= __m;
+ __h ^= __h >> 15;
+ return __h;
+}
+
+template <class _Size>
+struct __murmur2_or_cityhash<_Size, 64>
+{
+ _Size operator()(const void* __key, _Size __len);
+
+ private:
+ // Some primes between 2^63 and 2^64.
+ static const _Size __k0 = 0xc3a5c85c97cb3127ULL;
+ static const _Size __k1 = 0xb492b66fbe98f273ULL;
+ static const _Size __k2 = 0x9ae16a3b2f90404fULL;
+ static const _Size __k3 = 0xc949d7c7509e6557ULL;
+
+ static _Size __rotate(_Size __val, int __shift) {
+ return __shift == 0 ? __val : ((__val >> __shift) | (__val << (64 - __shift)));
+ }
+
+ static _Size __rotate_by_at_least_1(_Size __val, int __shift) {
+ return (__val >> __shift) | (__val << (64 - __shift));
+ }
+
+ static _Size __shift_mix(_Size __val) {
+ return __val ^ (__val >> 47);
+ }
+
+ static _Size __hash_len_16(_Size __u, _Size __v) {
+ const _Size __mul = 0x9ddfea08eb382d69ULL;
+ _Size __a = (__u ^ __v) * __mul;
+ __a ^= (__a >> 47);
+ _Size __b = (__v ^ __a) * __mul;
+ __b ^= (__b >> 47);
+ __b *= __mul;
+ return __b;
+ }
+
+ static _Size __hash_len_0_to_16(const char* __s, _Size __len) {
+ if (__len > 8) {
+ const _Size __a = __loadword<_Size>(__s);
+ const _Size __b = __loadword<_Size>(__s + __len - 8);
+ return __hash_len_16(__a, __rotate_by_at_least_1(__b + __len, __len)) ^ __b;
+ }
+ if (__len >= 4) {
+ const uint32_t __a = __loadword<uint32_t>(__s);
+ const uint32_t __b = __loadword<uint32_t>(__s + __len - 4);
+ return __hash_len_16(__len + (__a << 3), __b);
+ }
+ if (__len > 0) {
+ const unsigned char __a = __s[0];
+ const unsigned char __b = __s[__len >> 1];
+ const unsigned char __c = __s[__len - 1];
+ const uint32_t __y = static_cast<uint32_t>(__a) +
+ (static_cast<uint32_t>(__b) << 8);
+ const uint32_t __z = __len + (static_cast<uint32_t>(__c) << 2);
+ return __shift_mix(__y * __k2 ^ __z * __k3) * __k2;
+ }
+ return __k2;
+ }
+
+ static _Size __hash_len_17_to_32(const char *__s, _Size __len) {
+ const _Size __a = __loadword<_Size>(__s) * __k1;
+ const _Size __b = __loadword<_Size>(__s + 8);
+ const _Size __c = __loadword<_Size>(__s + __len - 8) * __k2;
+ const _Size __d = __loadword<_Size>(__s + __len - 16) * __k0;
+ return __hash_len_16(__rotate(__a - __b, 43) + __rotate(__c, 30) + __d,
+ __a + __rotate(__b ^ __k3, 20) - __c + __len);
+ }
+
+ // Return a 16-byte hash for 48 bytes. Quick and dirty.
+ // Callers do best to use "random-looking" values for a and b.
+ static pair<_Size, _Size> __weak_hash_len_32_with_seeds(
+ _Size __w, _Size __x, _Size __y, _Size __z, _Size __a, _Size __b) {
+ __a += __w;
+ __b = __rotate(__b + __a + __z, 21);
+ const _Size __c = __a;
+ __a += __x;
+ __a += __y;
+ __b += __rotate(__a, 44);
+ return pair<_Size, _Size>(__a + __z, __b + __c);
+ }
+
+ // Return a 16-byte hash for s[0] ... s[31], a, and b. Quick and dirty.
+ static pair<_Size, _Size> __weak_hash_len_32_with_seeds(
+ const char* __s, _Size __a, _Size __b) {
+ return __weak_hash_len_32_with_seeds(__loadword<_Size>(__s),
+ __loadword<_Size>(__s + 8),
+ __loadword<_Size>(__s + 16),
+ __loadword<_Size>(__s + 24),
+ __a,
+ __b);
+ }
+
+ // Return an 8-byte hash for 33 to 64 bytes.
+ static _Size __hash_len_33_to_64(const char *__s, size_t __len) {
+ _Size __z = __loadword<_Size>(__s + 24);
+ _Size __a = __loadword<_Size>(__s) +
+ (__len + __loadword<_Size>(__s + __len - 16)) * __k0;
+ _Size __b = __rotate(__a + __z, 52);
+ _Size __c = __rotate(__a, 37);
+ __a += __loadword<_Size>(__s + 8);
+ __c += __rotate(__a, 7);
+ __a += __loadword<_Size>(__s + 16);
+ _Size __vf = __a + __z;
+ _Size __vs = __b + __rotate(__a, 31) + __c;
+ __a = __loadword<_Size>(__s + 16) + __loadword<_Size>(__s + __len - 32);
+ __z += __loadword<_Size>(__s + __len - 8);
+ __b = __rotate(__a + __z, 52);
+ __c = __rotate(__a, 37);
+ __a += __loadword<_Size>(__s + __len - 24);
+ __c += __rotate(__a, 7);
+ __a += __loadword<_Size>(__s + __len - 16);
+ _Size __wf = __a + __z;
+ _Size __ws = __b + __rotate(__a, 31) + __c;
+ _Size __r = __shift_mix((__vf + __ws) * __k2 + (__wf + __vs) * __k0);
+ return __shift_mix(__r * __k0 + __vs) * __k2;
+ }
+};
+
+// cityhash64
+template <class _Size>
+_Size
+__murmur2_or_cityhash<_Size, 64>::operator()(const void* __key, _Size __len) _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK
+{
+ const char* __s = static_cast<const char*>(__key);
+ if (__len <= 32) {
+ if (__len <= 16) {
+ return __hash_len_0_to_16(__s, __len);
+ } else {
+ return __hash_len_17_to_32(__s, __len);
+ }
+ } else if (__len <= 64) {
+ return __hash_len_33_to_64(__s, __len);
+ }
+
+ // For strings over 64 bytes we hash the end first, and then as we
+ // loop we keep 56 bytes of state: v, w, x, y, and z.
+ _Size __x = __loadword<_Size>(__s + __len - 40);
+ _Size __y = __loadword<_Size>(__s + __len - 16) +
+ __loadword<_Size>(__s + __len - 56);
+ _Size __z = __hash_len_16(__loadword<_Size>(__s + __len - 48) + __len,
+ __loadword<_Size>(__s + __len - 24));
+ pair<_Size, _Size> __v = __weak_hash_len_32_with_seeds(__s + __len - 64, __len, __z);
+ pair<_Size, _Size> __w = __weak_hash_len_32_with_seeds(__s + __len - 32, __y + __k1, __x);
+ __x = __x * __k1 + __loadword<_Size>(__s);
+
+ // Decrease len to the nearest multiple of 64, and operate on 64-byte chunks.
+ __len = (__len - 1) & ~static_cast<_Size>(63);
+ do {
+ __x = __rotate(__x + __y + __v.first + __loadword<_Size>(__s + 8), 37) * __k1;
+ __y = __rotate(__y + __v.second + __loadword<_Size>(__s + 48), 42) * __k1;
+ __x ^= __w.second;
+ __y += __v.first + __loadword<_Size>(__s + 40);
+ __z = __rotate(__z + __w.first, 33) * __k1;
+ __v = __weak_hash_len_32_with_seeds(__s, __v.second * __k1, __x + __w.first);
+ __w = __weak_hash_len_32_with_seeds(__s + 32, __z + __w.second,
+ __y + __loadword<_Size>(__s + 16));
+ std::swap(__z, __x);
+ __s += 64;
+ __len -= 64;
+ } while (__len != 0);
+ return __hash_len_16(
+ __hash_len_16(__v.first, __w.first) + __shift_mix(__y) * __k1 + __z,
+ __hash_len_16(__v.second, __w.second) + __x);
+}
+
+template <class _Tp, size_t = sizeof(_Tp) / sizeof(size_t)>
+struct __scalar_hash;
+
+template <class _Tp>
+struct __scalar_hash<_Tp, 0>
+ : public unary_function<_Tp, size_t>
+{
+ _LIBCPP_INLINE_VISIBILITY
+ size_t operator()(_Tp __v) const _NOEXCEPT
+ {
+ union
+ {
+ _Tp __t;
+ size_t __a;
+ } __u;
+ __u.__a = 0;
+ __u.__t = __v;
+ return __u.__a;
+ }
+};
+
+template <class _Tp>
+struct __scalar_hash<_Tp, 1>
+ : public unary_function<_Tp, size_t>
+{
+ _LIBCPP_INLINE_VISIBILITY
+ size_t operator()(_Tp __v) const _NOEXCEPT
+ {
+ union
+ {
+ _Tp __t;
+ size_t __a;
+ } __u;
+ __u.__t = __v;
+ return __u.__a;
+ }
+};
+
+template <class _Tp>
+struct __scalar_hash<_Tp, 2>
+ : public unary_function<_Tp, size_t>
+{
+ _LIBCPP_INLINE_VISIBILITY
+ size_t operator()(_Tp __v) const _NOEXCEPT
+ {
+ union
+ {
+ _Tp __t;
+ struct
+ {
+ size_t __a;
+ size_t __b;
+ } __s;
+ } __u;
+ __u.__t = __v;
+ return __murmur2_or_cityhash<size_t>()(&__u, sizeof(__u));
+ }
+};
+
+template <class _Tp>
+struct __scalar_hash<_Tp, 3>
+ : public unary_function<_Tp, size_t>
+{
+ _LIBCPP_INLINE_VISIBILITY
+ size_t operator()(_Tp __v) const _NOEXCEPT
+ {
+ union
+ {
+ _Tp __t;
+ struct
+ {
+ size_t __a;
+ size_t __b;
+ size_t __c;
+ } __s;
+ } __u;
+ __u.__t = __v;
+ return __murmur2_or_cityhash<size_t>()(&__u, sizeof(__u));
+ }
+};
+
+template <class _Tp>
+struct __scalar_hash<_Tp, 4>
+ : public unary_function<_Tp, size_t>
+{
+ _LIBCPP_INLINE_VISIBILITY
+ size_t operator()(_Tp __v) const _NOEXCEPT
+ {
+ union
+ {
+ _Tp __t;
+ struct
+ {
+ size_t __a;
+ size_t __b;
+ size_t __c;
+ size_t __d;
+ } __s;
+ } __u;
+ __u.__t = __v;
+ return __murmur2_or_cityhash<size_t>()(&__u, sizeof(__u));
+ }
+};
+
+struct _PairT {
+ size_t first;
+ size_t second;
+};
+
+_LIBCPP_INLINE_VISIBILITY
+inline size_t __hash_combine(size_t __lhs, size_t __rhs) _NOEXCEPT {
+ typedef __scalar_hash<_PairT> _HashT;
+ const _PairT __p = {__lhs, __rhs};
+ return _HashT()(__p);
+}
+
+template<class _Tp>
+struct _LIBCPP_TEMPLATE_VIS hash<_Tp*>
+ : public unary_function<_Tp*, size_t>
+{
+ _LIBCPP_INLINE_VISIBILITY
+ size_t operator()(_Tp* __v) const _NOEXCEPT
+ {
+ union
+ {
+ _Tp* __t;
+ size_t __a;
+ } __u;
+ __u.__t = __v;
+ return __murmur2_or_cityhash<size_t>()(&__u, sizeof(__u));
+ }
+};
+
+
+template <>
+struct _LIBCPP_TEMPLATE_VIS hash<bool>
+ : public unary_function<bool, size_t>
+{
+ _LIBCPP_INLINE_VISIBILITY
+ size_t operator()(bool __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
+};
+
+template <>
+struct _LIBCPP_TEMPLATE_VIS hash<char>
+ : public unary_function<char, size_t>
+{
+ _LIBCPP_INLINE_VISIBILITY
+ size_t operator()(char __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
+};
+
+template <>
+struct _LIBCPP_TEMPLATE_VIS hash<signed char>
+ : public unary_function<signed char, size_t>
+{
+ _LIBCPP_INLINE_VISIBILITY
+ size_t operator()(signed char __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
+};
+
+template <>
+struct _LIBCPP_TEMPLATE_VIS hash<unsigned char>
+ : public unary_function<unsigned char, size_t>
+{
+ _LIBCPP_INLINE_VISIBILITY
+ size_t operator()(unsigned char __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
+};
+
+#ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
+
+template <>
+struct _LIBCPP_TEMPLATE_VIS hash<char16_t>
+ : public unary_function<char16_t, size_t>
+{
+ _LIBCPP_INLINE_VISIBILITY
+ size_t operator()(char16_t __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
+};
+
+template <>
+struct _LIBCPP_TEMPLATE_VIS hash<char32_t>
+ : public unary_function<char32_t, size_t>
+{
+ _LIBCPP_INLINE_VISIBILITY
+ size_t operator()(char32_t __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
+};
+
+#endif // _LIBCPP_HAS_NO_UNICODE_CHARS
+
+template <>
+struct _LIBCPP_TEMPLATE_VIS hash<wchar_t>
+ : public unary_function<wchar_t, size_t>
+{
+ _LIBCPP_INLINE_VISIBILITY
+ size_t operator()(wchar_t __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
+};
+
+template <>
+struct _LIBCPP_TEMPLATE_VIS hash<short>
+ : public unary_function<short, size_t>
+{
+ _LIBCPP_INLINE_VISIBILITY
+ size_t operator()(short __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
+};
+
+template <>
+struct _LIBCPP_TEMPLATE_VIS hash<unsigned short>
+ : public unary_function<unsigned short, size_t>
+{
+ _LIBCPP_INLINE_VISIBILITY
+ size_t operator()(unsigned short __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
+};
+
+template <>
+struct _LIBCPP_TEMPLATE_VIS hash<int>
+ : public unary_function<int, size_t>
+{
+ _LIBCPP_INLINE_VISIBILITY
+ size_t operator()(int __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
+};
+
+template <>
+struct _LIBCPP_TEMPLATE_VIS hash<unsigned int>
+ : public unary_function<unsigned int, size_t>
+{
+ _LIBCPP_INLINE_VISIBILITY
+ size_t operator()(unsigned int __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
+};
+
+template <>
+struct _LIBCPP_TEMPLATE_VIS hash<long>
+ : public unary_function<long, size_t>
+{
+ _LIBCPP_INLINE_VISIBILITY
+ size_t operator()(long __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
+};
+
+template <>
+struct _LIBCPP_TEMPLATE_VIS hash<unsigned long>
+ : public unary_function<unsigned long, size_t>
+{
+ _LIBCPP_INLINE_VISIBILITY
+ size_t operator()(unsigned long __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
+};
+
+template <>
+struct _LIBCPP_TEMPLATE_VIS hash<long long>
+ : public __scalar_hash<long long>
+{
+};
+
+template <>
+struct _LIBCPP_TEMPLATE_VIS hash<unsigned long long>
+ : public __scalar_hash<unsigned long long>
+{
+};
+
+#ifndef _LIBCPP_HAS_NO_INT128
+
+template <>
+struct _LIBCPP_TEMPLATE_VIS hash<__int128_t>
+ : public __scalar_hash<__int128_t>
+{
+};
+
+template <>
+struct _LIBCPP_TEMPLATE_VIS hash<__uint128_t>
+ : public __scalar_hash<__uint128_t>
+{
+};
+
+#endif
+
+template <>
+struct _LIBCPP_TEMPLATE_VIS hash<float>
+ : public __scalar_hash<float>
+{
+ _LIBCPP_INLINE_VISIBILITY
+ size_t operator()(float __v) const _NOEXCEPT
+ {
+ // -0.0 and 0.0 should return same hash
+ if (__v == 0)
+ return 0;
+ return __scalar_hash<float>::operator()(__v);
+ }
+};
+
+template <>
+struct _LIBCPP_TEMPLATE_VIS hash<double>
+ : public __scalar_hash<double>
+{
+ _LIBCPP_INLINE_VISIBILITY
+ size_t operator()(double __v) const _NOEXCEPT
+ {
+ // -0.0 and 0.0 should return same hash
+ if (__v == 0)
+ return 0;
+ return __scalar_hash<double>::operator()(__v);
+ }
+};
+
+template <>
+struct _LIBCPP_TEMPLATE_VIS hash<long double>
+ : public __scalar_hash<long double>
+{
+ _LIBCPP_INLINE_VISIBILITY
+ size_t operator()(long double __v) const _NOEXCEPT
+ {
+ // -0.0 and 0.0 should return same hash
+ if (__v == 0)
+ return 0;
+#if defined(__i386__)
+ // Zero out padding bits
+ union
+ {
+ long double __t;
+ struct
+ {
+ size_t __a;
+ size_t __b;
+ size_t __c;
+ size_t __d;
+ } __s;
+ } __u;
+ __u.__s.__a = 0;
+ __u.__s.__b = 0;
+ __u.__s.__c = 0;
+ __u.__s.__d = 0;
+ __u.__t = __v;
+ return __u.__s.__a ^ __u.__s.__b ^ __u.__s.__c ^ __u.__s.__d;
+#elif defined(__x86_64__)
+ // Zero out padding bits
+ union
+ {
+ long double __t;
+ struct
+ {
+ size_t __a;
+ size_t __b;
+ } __s;
+ } __u;
+ __u.__s.__a = 0;
+ __u.__s.__b = 0;
+ __u.__t = __v;
+ return __u.__s.__a ^ __u.__s.__b;
+#else
+ return __scalar_hash<long double>::operator()(__v);
+#endif
+ }
+};
+
+#if _LIBCPP_STD_VER > 11
+
+template <class _Tp, bool = is_enum<_Tp>::value>
+struct _LIBCPP_TEMPLATE_VIS __enum_hash
+ : public unary_function<_Tp, size_t>
+{
+ _LIBCPP_INLINE_VISIBILITY
+ size_t operator()(_Tp __v) const _NOEXCEPT
+ {
+ typedef typename underlying_type<_Tp>::type type;
+ return hash<type>{}(static_cast<type>(__v));
+ }
+};
+template <class _Tp>
+struct _LIBCPP_TEMPLATE_VIS __enum_hash<_Tp, false> {
+ __enum_hash() = delete;
+ __enum_hash(__enum_hash const&) = delete;
+ __enum_hash& operator=(__enum_hash const&) = delete;
+};
+
+template <class _Tp>
+struct _LIBCPP_TEMPLATE_VIS hash : public __enum_hash<_Tp>
+{
+};
+#endif
+
+#if _LIBCPP_STD_VER > 14
+
+template <>
+struct _LIBCPP_TEMPLATE_VIS hash<nullptr_t>
+ : public unary_function<nullptr_t, size_t>
+{
+ _LIBCPP_INLINE_VISIBILITY
+ size_t operator()(nullptr_t) const _NOEXCEPT {
+ return 662607004ull;
+ }
+};
+#endif
+
+#ifndef _LIBCPP_CXX03_LANG
+template <class _Key, class _Hash = std::hash<_Key> >
+using __has_enabled_hash = integral_constant<bool,
+ is_default_constructible<_Hash>::value &&
+ is_copy_constructible<_Hash>::value &&
+ is_move_constructible<_Hash>::value &&
+ __invokable_r<size_t, _Hash, _Key const&>::value
+>;
+
+#if _LIBCPP_STD_VER > 14
+template <class _Type, class>
+using __enable_hash_helper_imp = _Type;
+
+template <class _Type, class ..._Keys>
+using __enable_hash_helper = __enable_hash_helper_imp<_Type,
+ typename enable_if<__all<__has_enabled_hash<_Keys>::value...>::value>::type
+>;
+#else
+template <class _Type, class ...>
+using __enable_hash_helper = _Type;
+#endif
+
+#endif // !_LIBCPP_CXX03_LANG
+
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP_UTILITY