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Implement P0513R0 - "Poisoning the Hash"

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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

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@292684 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Eric Fiselier
2017-01-21 00:02:12 +00:00
parent ee856f131d
commit 952eaecfc6
31 changed files with 1470 additions and 653 deletions
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358
include/memory
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@@ -3021,360 +3021,13 @@ template<class _Tp, class... _Args>
#endif // _LIBCPP_STD_VER > 11
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 <class _Tp, class _Dp>
#ifdef _LIBCPP_CXX03_LANG
struct _LIBCPP_TEMPLATE_VIS hash<unique_ptr<_Tp, _Dp> >
#else
struct _LIBCPP_TEMPLATE_VIS hash<__enable_hash_helper<
unique_ptr<_Tp, _Dp>, typename unique_ptr<_Tp, _Dp>::pointer>>
#endif
{
typedef unique_ptr<_Tp, _Dp> argument_type;
typedef size_t result_type;
@@ -5540,6 +5193,7 @@ struct _LIBCPP_TEMPLATE_VIS hash<shared_ptr<_Tp> >
{
typedef shared_ptr<_Tp> argument_type;
typedef size_t result_type;
_LIBCPP_INLINE_VISIBILITY
result_type operator()(const argument_type& __ptr) const _NOEXCEPT
{