//
//===----------------------------------------------------------------------===//
//
-// This file defines utilities for computing hash values for various data types.
+// This file implements the newly proposed standard C++ interfaces for hashing
+// arbitrary data and building hash functions for user-defined types. This
+// interface was originally proposed in N3333[1] and is currently under review
+// for inclusion in a future TR and/or standard.
+//
+// The primary interfaces provide are comprised of one type and three functions:
+//
+// -- 'hash_code' class is an opaque type representing the hash code for some
+// data. It is the intended product of hashing, and can be used to implement
+// hash tables, checksumming, and other common uses of hashes. It is not an
+// integer type (although it can be converted to one) because it is risky
+// to assume much about the internals of a hash_code. In particular, each
+// execution of the program has a high probability of producing a different
+// hash_code for a given input. Thus their values are not stable to save or
+// persist, and should only be used during the execution for the
+// construction of hashing datastructures.
+//
+// -- 'hash_value' is a function designed to be overloaded for each
+// user-defined type which wishes to be used within a hashing context. It
+// should be overloaded within the user-defined type's namespace and found
+// via ADL. Overloads for primitive types are provided by this library.
+//
+// -- 'hash_combine' and 'hash_combine_range' are functions designed to aid
+// programmers in easily and intuitively combining a set of data into
+// a single hash_code for their object. They should only logically be used
+// within the implementation of a 'hash_value' routine or similar context.
+//
+// Note that 'hash_combine_range' contains very special logic for hashing
+// a contiguous array of integers or pointers. This logic is *extremely* fast,
+// on a modern Intel "Gainestown" Xeon (Nehalem uarch) @2.2 GHz, these were
+// benchmarked at over 6.5 GiB/s for large keys, and <20 cycles/hash for keys
+// under 32-bytes.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ADT_HASHING_H
#define LLVM_ADT_HASHING_H
-#include "llvm/ADT/ArrayRef.h"
-#include "llvm/ADT/StringRef.h"
-#include "llvm/Support/AlignOf.h"
-#include "llvm/Support/Compiler.h"
+#include "llvm/ADT/STLExtras.h"
#include "llvm/Support/DataTypes.h"
+#include "llvm/Support/Host.h"
+#include "llvm/Support/SwapByteOrder.h"
+#include "llvm/Support/type_traits.h"
+#include <algorithm>
+#include <cassert>
#include <cstring>
+#include <iterator>
+#include <utility>
+
+// Allow detecting C++11 feature availability when building with Clang without
+// breaking other compilers.
+#ifndef __has_feature
+# define __has_feature(x) 0
+#endif
namespace llvm {
-/// Class to compute a hash value from multiple data fields of arbitrary
-/// types. Note that if you are hashing a single data type, such as a
-/// string, it may be cheaper to use a hash algorithm that is tailored
-/// for that specific data type.
-/// Typical Usage:
-/// GeneralHash Hash;
-/// Hash.add(someValue);
-/// Hash.add(someOtherValue);
-/// return Hash.finish();
-/// Adapted from MurmurHash2 by Austin Appleby
-class GeneralHash {
-private:
- enum {
- M = 0x5bd1e995
- };
- unsigned Hash;
- unsigned Count;
+/// \brief An opaque object representing a hash code.
+///
+/// This object represents the result of hashing some entity. It is intended to
+/// be used to implement hashtables or other hashing-based data structures.
+/// While it wraps and exposes a numeric value, this value should not be
+/// trusted to be stable or predictable across processes or executions.
+///
+/// In order to obtain the hash_code for an object 'x':
+/// \code
+/// using llvm::hash_value;
+/// llvm::hash_code code = hash_value(x);
+/// \endcode
+class hash_code {
+ size_t value;
+
public:
- GeneralHash(unsigned Seed = 0) : Hash(Seed), Count(0) {}
+ /// \brief Default construct a hash_code.
+ /// Note that this leaves the value uninitialized.
+ hash_code() {}
+
+ /// \brief Form a hash code directly from a numerical value.
+ hash_code(size_t value) : value(value) {}
+
+ /// \brief Convert the hash code to its numerical value for use.
+ /*explicit*/ operator size_t() const { return value; }
- /// Add a pointer value.
- /// Note: this adds pointers to the hash using sizes and endianness that
- /// depend on the host. It doesn't matter however, because hashing on
- /// pointer values is inherently unstable.
- template<typename T>
- GeneralHash& add(const T *PtrVal) {
- addBits(&PtrVal, &PtrVal + 1);
- return *this;
+ friend bool operator==(const hash_code &lhs, const hash_code &rhs) {
+ return lhs.value == rhs.value;
}
-
- /// Add an ArrayRef of arbitrary data.
- template<typename T>
- GeneralHash& add(ArrayRef<T> ArrayVal) {
- addBits(ArrayVal.begin(), ArrayVal.end());
- return *this;
- }
-
- /// Add a string
- GeneralHash& add(StringRef StrVal) {
- addBits(StrVal.begin(), StrVal.end());
- return *this;
- }
-
- /// Add an signed 32-bit integer.
- GeneralHash& add(int32_t Data) {
- addInt(uint32_t(Data));
- return *this;
- }
-
- /// Add an unsigned 32-bit integer.
- GeneralHash& add(uint32_t Data) {
- addInt(Data);
- return *this;
- }
-
- /// Add an signed 64-bit integer.
- GeneralHash& add(int64_t Data) {
- addInt(uint64_t(Data));
- return *this;
- }
-
- /// Add an unsigned 64-bit integer.
- GeneralHash& add(uint64_t Data) {
- addInt(Data);
- return *this;
- }
-
- /// Add a float
- GeneralHash& add(float Data) {
- union {
- float D; uint32_t I;
- };
- D = Data;
- addInt(I);
- return *this;
- }
-
- /// Add a double
- GeneralHash& add(double Data) {
- union {
- double D; uint64_t I;
- };
- D = Data;
- addInt(I);
- return *this;
- }
-
- // Do a few final mixes of the hash to ensure the last few
- // bytes are well-incorporated.
- unsigned finish() {
- mix(Count);
- Hash ^= Hash >> 13;
- Hash *= M;
- Hash ^= Hash >> 15;
- return Hash;
- }
-
-private:
- void mix(uint32_t Data) {
- ++Count;
- Data *= M;
- Data ^= Data >> 24;
- Data *= M;
- Hash *= M;
- Hash ^= Data;
- }
-
- // Add a single uint32 value
- void addInt(uint32_t Val) {
- mix(Val);
- }
-
- // Add a uint64 value
- void addInt(uint64_t Val) {
- mix(uint32_t(Val >> 32));
- mix(uint32_t(Val));
- }
-
- // Add a range of bytes from I to E.
- void addBytes(const char *I, const char *E) {
- uint32_t Data;
- // Note that aliasing rules forbid us from dereferencing
- // reinterpret_cast<uint32_t *>(I) even if I happens to be suitably
- // aligned, so we use memcpy instead.
- for (; E - I >= ptrdiff_t(sizeof Data); I += sizeof Data) {
- // A clever compiler should be able to turn this memcpy into a single
- // aligned or unaligned load (depending on the alignment of the type T
- // that was used in the call to addBits).
- std::memcpy(&Data, I, sizeof Data);
- mix(Data);
- }
- if (I != E) {
- Data = 0;
- std::memcpy(&Data, I, E - I);
- mix(Data);
+ friend bool operator!=(const hash_code &lhs, const hash_code &rhs) {
+ return lhs.value != rhs.value;
+ }
+
+ /// \brief Allow a hash_code to be directly run through hash_value.
+ friend size_t hash_value(const hash_code &code) { return code.value; }
+};
+
+/// \brief Compute a hash_code for any integer value.
+///
+/// Note that this function is intended to compute the same hash_code for
+/// a particular value without regard to the pre-promotion type. This is in
+/// contrast to hash_combine which may produce different hash_codes for
+/// differing argument types even if they would implicit promote to a common
+/// type without changing the value.
+template <typename T>
+typename enable_if<is_integral_or_enum<T>, hash_code>::type hash_value(T value);
+
+/// \brief Compute a hash_code for a pointer's address.
+///
+/// N.B.: This hashes the *address*. Not the value and not the type.
+template <typename T> hash_code hash_value(const T *ptr);
+
+/// \brief Compute a hash_code for a pair of objects.
+template <typename T, typename U>
+hash_code hash_value(const std::pair<T, U> &arg);
+
+/// \brief Compute a hash_code for a standard string.
+template <typename T>
+hash_code hash_value(const std::basic_string<T> &arg);
+
+
+/// \brief Override the execution seed with a fixed value.
+///
+/// This hashing library uses a per-execution seed designed to change on each
+/// run with high probability in order to ensure that the hash codes are not
+/// attackable and to ensure that output which is intended to be stable does
+/// not rely on the particulars of the hash codes produced.
+///
+/// That said, there are use cases where it is important to be able to
+/// reproduce *exactly* a specific behavior. To that end, we provide a function
+/// which will forcibly set the seed to a fixed value. This must be done at the
+/// start of the program, before any hashes are computed. Also, it cannot be
+/// undone. This makes it thread-hostile and very hard to use outside of
+/// immediately on start of a simple program designed for reproducible
+/// behavior.
+void set_fixed_execution_hash_seed(size_t fixed_value);
+
+
+// All of the implementation details of actually computing the various hash
+// code values are held within this namespace. These routines are included in
+// the header file mainly to allow inlining and constant propagation.
+namespace hashing {
+namespace detail {
+
+inline uint64_t fetch64(const char *p) {
+ uint64_t result;
+ memcpy(&result, p, sizeof(result));
+ if (sys::IsBigEndianHost)
+ return sys::SwapByteOrder(result);
+ return result;
+}
+
+inline uint32_t fetch32(const char *p) {
+ uint32_t result;
+ memcpy(&result, p, sizeof(result));
+ if (sys::IsBigEndianHost)
+ return sys::SwapByteOrder(result);
+ return result;
+}
+
+/// Some primes between 2^63 and 2^64 for various uses.
+static const uint64_t k0 = 0xc3a5c85c97cb3127ULL;
+static const uint64_t k1 = 0xb492b66fbe98f273ULL;
+static const uint64_t k2 = 0x9ae16a3b2f90404fULL;
+static const uint64_t k3 = 0xc949d7c7509e6557ULL;
+
+/// \brief Bitwise right rotate.
+/// Normally this will compile to a single instruction, especially if the
+/// shift is a manifest constant.
+inline uint64_t rotate(uint64_t val, size_t shift) {
+ // Avoid shifting by 64: doing so yields an undefined result.
+ return shift == 0 ? val : ((val >> shift) | (val << (64 - shift)));
+}
+
+inline uint64_t shift_mix(uint64_t val) {
+ return val ^ (val >> 47);
+}
+
+inline uint64_t hash_16_bytes(uint64_t low, uint64_t high) {
+ // Murmur-inspired hashing.
+ const uint64_t kMul = 0x9ddfea08eb382d69ULL;
+ uint64_t a = (low ^ high) * kMul;
+ a ^= (a >> 47);
+ uint64_t b = (high ^ a) * kMul;
+ b ^= (b >> 47);
+ b *= kMul;
+ return b;
+}
+
+inline uint64_t hash_1to3_bytes(const char *s, size_t len, uint64_t seed) {
+ uint8_t a = s[0];
+ uint8_t b = s[len >> 1];
+ uint8_t c = s[len - 1];
+ uint32_t y = static_cast<uint32_t>(a) + (static_cast<uint32_t>(b) << 8);
+ uint32_t z = len + (static_cast<uint32_t>(c) << 2);
+ return shift_mix(y * k2 ^ z * k3 ^ seed) * k2;
+}
+
+inline uint64_t hash_4to8_bytes(const char *s, size_t len, uint64_t seed) {
+ uint64_t a = fetch32(s);
+ return hash_16_bytes(len + (a << 3), seed ^ fetch32(s + len - 4));
+}
+
+inline uint64_t hash_9to16_bytes(const char *s, size_t len, uint64_t seed) {
+ uint64_t a = fetch64(s);
+ uint64_t b = fetch64(s + len - 8);
+ return hash_16_bytes(seed ^ a, rotate(b + len, len)) ^ b;
+}
+
+inline uint64_t hash_17to32_bytes(const char *s, size_t len, uint64_t seed) {
+ uint64_t a = fetch64(s) * k1;
+ uint64_t b = fetch64(s + 8);
+ uint64_t c = fetch64(s + len - 8) * k2;
+ uint64_t d = fetch64(s + len - 16) * k0;
+ return hash_16_bytes(rotate(a - b, 43) + rotate(c ^ seed, 30) + d,
+ a + rotate(b ^ k3, 20) - c + len + seed);
+}
+
+inline uint64_t hash_33to64_bytes(const char *s, size_t len, uint64_t seed) {
+ uint64_t z = fetch64(s + 24);
+ uint64_t a = fetch64(s) + (len + fetch64(s + len - 16)) * k0;
+ uint64_t b = rotate(a + z, 52);
+ uint64_t c = rotate(a, 37);
+ a += fetch64(s + 8);
+ c += rotate(a, 7);
+ a += fetch64(s + 16);
+ uint64_t vf = a + z;
+ uint64_t vs = b + rotate(a, 31) + c;
+ a = fetch64(s + 16) + fetch64(s + len - 32);
+ z = fetch64(s + len - 8);
+ b = rotate(a + z, 52);
+ c = rotate(a, 37);
+ a += fetch64(s + len - 24);
+ c += rotate(a, 7);
+ a += fetch64(s + len - 16);
+ uint64_t wf = a + z;
+ uint64_t ws = b + rotate(a, 31) + c;
+ uint64_t r = shift_mix((vf + ws) * k2 + (wf + vs) * k0);
+ return shift_mix((seed ^ (r * k0)) + vs) * k2;
+}
+
+inline uint64_t hash_short(const char *s, size_t length, uint64_t seed) {
+ if (length >= 4 && length <= 8)
+ return hash_4to8_bytes(s, length, seed);
+ if (length > 8 && length <= 16)
+ return hash_9to16_bytes(s, length, seed);
+ if (length > 16 && length <= 32)
+ return hash_17to32_bytes(s, length, seed);
+ if (length > 32)
+ return hash_33to64_bytes(s, length, seed);
+ if (length != 0)
+ return hash_1to3_bytes(s, length, seed);
+
+ return k2 ^ seed;
+}
+
+/// \brief The intermediate state used during hashing.
+/// Currently, the algorithm for computing hash codes is based on CityHash and
+/// keeps 56 bytes of arbitrary state.
+struct hash_state {
+ uint64_t h0, h1, h2, h3, h4, h5, h6;
+ uint64_t seed;
+
+ /// \brief Create a new hash_state structure and initialize it based on the
+ /// seed and the first 64-byte chunk.
+ /// This effectively performs the initial mix.
+ static hash_state create(const char *s, uint64_t seed) {
+ hash_state state = {
+ 0, seed, hash_16_bytes(seed, k1), rotate(seed ^ k1, 49),
+ seed * k1, shift_mix(seed), 0, seed };
+ state.h6 = hash_16_bytes(state.h4, state.h5);
+ state.mix(s);
+ return state;
+ }
+
+ /// \brief Mix 32-bytes from the input sequence into the 16-bytes of 'a'
+ /// and 'b', including whatever is already in 'a' and 'b'.
+ static void mix_32_bytes(const char *s, uint64_t &a, uint64_t &b) {
+ a += fetch64(s);
+ uint64_t c = fetch64(s + 24);
+ b = rotate(b + a + c, 21);
+ uint64_t d = a;
+ a += fetch64(s + 8) + fetch64(s + 16);
+ b += rotate(a, 44) + d;
+ a += c;
+ }
+
+ /// \brief Mix in a 64-byte buffer of data.
+ /// We mix all 64 bytes even when the chunk length is smaller, but we
+ /// record the actual length.
+ void mix(const char *s) {
+ h0 = rotate(h0 + h1 + h3 + fetch64(s + 8), 37) * k1;
+ h1 = rotate(h1 + h4 + fetch64(s + 48), 42) * k1;
+ h0 ^= h6;
+ h1 += h3 + fetch64(s + 40);
+ h2 = rotate(h2 + h5, 33) * k1;
+ h3 = h4 * k1;
+ h4 = h0 + h5;
+ mix_32_bytes(s, h3, h4);
+ h5 = h2 + h6;
+ h6 = h1 + fetch64(s + 16);
+ mix_32_bytes(s + 32, h5, h6);
+ std::swap(h2, h0);
+ }
+
+ /// \brief Compute the final 64-bit hash code value based on the current
+ /// state and the length of bytes hashed.
+ uint64_t finalize(size_t length) {
+ return hash_16_bytes(hash_16_bytes(h3, h5) + shift_mix(h1) * k1 + h2,
+ hash_16_bytes(h4, h6) + shift_mix(length) * k1 + h0);
+ }
+};
+
+
+/// \brief A global, fixed seed-override variable.
+///
+/// This variable can be set using the \see llvm::set_fixed_execution_seed
+/// function. See that function for details. Do not, under any circumstances,
+/// set or read this variable.
+extern size_t fixed_seed_override;
+
+inline size_t get_execution_seed() {
+ // FIXME: This needs to be a per-execution seed. This is just a placeholder
+ // implementation. Switching to a per-execution seed is likely to flush out
+ // instability bugs and so will happen as its own commit.
+ //
+ // However, if there is a fixed seed override set the first time this is
+ // called, return that instead of the per-execution seed.
+ const uint64_t seed_prime = 0xff51afd7ed558ccdULL;
+ static size_t seed = fixed_seed_override ? fixed_seed_override
+ : (size_t)seed_prime;
+ return seed;
+}
+
+
+/// \brief Trait to indicate whether a type's bits can be hashed directly.
+///
+/// A type trait which is true if we want to combine values for hashing by
+/// reading the underlying data. It is false if values of this type must
+/// first be passed to hash_value, and the resulting hash_codes combined.
+//
+// FIXME: We want to replace is_integral_or_enum and is_pointer here with
+// a predicate which asserts that comparing the underlying storage of two
+// values of the type for equality is equivalent to comparing the two values
+// for equality. For all the platforms we care about, this holds for integers
+// and pointers, but there are platforms where it doesn't and we would like to
+// support user-defined types which happen to satisfy this property.
+template <typename T> struct is_hashable_data
+ : integral_constant<bool, ((is_integral_or_enum<T>::value ||
+ is_pointer<T>::value) &&
+ 64 % sizeof(T) == 0)> {};
+
+// Special case std::pair to detect when both types are viable and when there
+// is no alignment-derived padding in the pair. This is a bit of a lie because
+// std::pair isn't truly POD, but it's close enough in all reasonable
+// implementations for our use case of hashing the underlying data.
+template <typename T, typename U> struct is_hashable_data<std::pair<T, U> >
+ : integral_constant<bool, (is_hashable_data<T>::value &&
+ is_hashable_data<U>::value &&
+ (sizeof(T) + sizeof(U)) ==
+ sizeof(std::pair<T, U>))> {};
+
+/// \brief Helper to get the hashable data representation for a type.
+/// This variant is enabled when the type itself can be used.
+template <typename T>
+typename enable_if<is_hashable_data<T>, T>::type
+get_hashable_data(const T &value) {
+ return value;
+}
+/// \brief Helper to get the hashable data representation for a type.
+/// This variant is enabled when we must first call hash_value and use the
+/// result as our data.
+template <typename T>
+typename enable_if_c<!is_hashable_data<T>::value, size_t>::type
+get_hashable_data(const T &value) {
+ using ::llvm::hash_value;
+ return hash_value(value);
+}
+
+/// \brief Helper to store data from a value into a buffer and advance the
+/// pointer into that buffer.
+///
+/// This routine first checks whether there is enough space in the provided
+/// buffer, and if not immediately returns false. If there is space, it
+/// copies the underlying bytes of value into the buffer, advances the
+/// buffer_ptr past the copied bytes, and returns true.
+template <typename T>
+bool store_and_advance(char *&buffer_ptr, char *buffer_end, const T& value,
+ size_t offset = 0) {
+ size_t store_size = sizeof(value) - offset;
+ if (buffer_ptr + store_size > buffer_end)
+ return false;
+ const char *value_data = reinterpret_cast<const char *>(&value);
+ memcpy(buffer_ptr, value_data + offset, store_size);
+ buffer_ptr += store_size;
+ return true;
+}
+
+/// \brief Implement the combining of integral values into a hash_code.
+///
+/// This overload is selected when the value type of the iterator is
+/// integral. Rather than computing a hash_code for each object and then
+/// combining them, this (as an optimization) directly combines the integers.
+template <typename InputIteratorT>
+hash_code hash_combine_range_impl(InputIteratorT first, InputIteratorT last) {
+ const size_t seed = get_execution_seed();
+ char buffer[64], *buffer_ptr = buffer;
+ char *const buffer_end = buffer_ptr + array_lengthof(buffer);
+ while (first != last && store_and_advance(buffer_ptr, buffer_end,
+ get_hashable_data(*first)))
+ ++first;
+ if (first == last)
+ return hash_short(buffer, buffer_ptr - buffer, seed);
+ assert(buffer_ptr == buffer_end);
+
+ hash_state state = state.create(buffer, seed);
+ size_t length = 64;
+ while (first != last) {
+ // Fill up the buffer. We don't clear it, which re-mixes the last round
+ // when only a partial 64-byte chunk is left.
+ buffer_ptr = buffer;
+ while (first != last && store_and_advance(buffer_ptr, buffer_end,
+ get_hashable_data(*first)))
+ ++first;
+
+ // Rotate the buffer if we did a partial fill in order to simulate doing
+ // a mix of the last 64-bytes. That is how the algorithm works when we
+ // have a contiguous byte sequence, and we want to emulate that here.
+ std::rotate(buffer, buffer_ptr, buffer_end);
+
+ // Mix this chunk into the current state.
+ state.mix(buffer);
+ length += buffer_ptr - buffer;
+ };
+
+ return state.finalize(length);
+}
+
+/// \brief Implement the combining of integral values into a hash_code.
+///
+/// This overload is selected when the value type of the iterator is integral
+/// and when the input iterator is actually a pointer. Rather than computing
+/// a hash_code for each object and then combining them, this (as an
+/// optimization) directly combines the integers. Also, because the integers
+/// are stored in contiguous memory, this routine avoids copying each value
+/// and directly reads from the underlying memory.
+template <typename ValueT>
+typename enable_if<is_hashable_data<ValueT>, hash_code>::type
+hash_combine_range_impl(ValueT *first, ValueT *last) {
+ const size_t seed = get_execution_seed();
+ const char *s_begin = reinterpret_cast<const char *>(first);
+ const char *s_end = reinterpret_cast<const char *>(last);
+ const size_t length = std::distance(s_begin, s_end);
+ if (length <= 64)
+ return hash_short(s_begin, length, seed);
+
+ const char *s_aligned_end = s_begin + (length & ~63);
+ hash_state state = state.create(s_begin, seed);
+ s_begin += 64;
+ while (s_begin != s_aligned_end) {
+ state.mix(s_begin);
+ s_begin += 64;
+ }
+ if (length & 63)
+ state.mix(s_end - 64);
+
+ return state.finalize(length);
+}
+
+} // namespace detail
+} // namespace hashing
+
+
+/// \brief Compute a hash_code for a sequence of values.
+///
+/// This hashes a sequence of values. It produces the same hash_code as
+/// 'hash_combine(a, b, c, ...)', but can run over arbitrary sized sequences
+/// and is significantly faster given pointers and types which can be hashed as
+/// a sequence of bytes.
+template <typename InputIteratorT>
+hash_code hash_combine_range(InputIteratorT first, InputIteratorT last) {
+ return ::llvm::hashing::detail::hash_combine_range_impl(first, last);
+}
+
+
+// Implementation details for hash_combine.
+namespace hashing {
+namespace detail {
+
+/// \brief Helper class to manage the recursive combining of hash_combine
+/// arguments.
+///
+/// This class exists to manage the state and various calls involved in the
+/// recursive combining of arguments used in hash_combine. It is particularly
+/// useful at minimizing the code in the recursive calls to ease the pain
+/// caused by a lack of variadic functions.
+struct hash_combine_recursive_helper {
+ char buffer[64];
+ hash_state state;
+ const size_t seed;
+
+public:
+ /// \brief Construct a recursive hash combining helper.
+ ///
+ /// This sets up the state for a recursive hash combine, including getting
+ /// the seed and buffer setup.
+ hash_combine_recursive_helper()
+ : seed(get_execution_seed()) {}
+
+ /// \brief Combine one chunk of data into the current in-flight hash.
+ ///
+ /// This merges one chunk of data into the hash. First it tries to buffer
+ /// the data. If the buffer is full, it hashes the buffer into its
+ /// hash_state, empties it, and then merges the new chunk in. This also
+ /// handles cases where the data straddles the end of the buffer.
+ template <typename T>
+ char *combine_data(size_t &length, char *buffer_ptr, char *buffer_end, T data) {
+ if (!store_and_advance(buffer_ptr, buffer_end, data)) {
+ // Check for skew which prevents the buffer from being packed, and do
+ // a partial store into the buffer to fill it. This is only a concern
+ // with the variadic combine because that formation can have varying
+ // argument types.
+ size_t partial_store_size = buffer_end - buffer_ptr;
+ memcpy(buffer_ptr, &data, partial_store_size);
+
+ // If the store fails, our buffer is full and ready to hash. We have to
+ // either initialize the hash state (on the first full buffer) or mix
+ // this buffer into the existing hash state. Length tracks the *hashed*
+ // length, not the buffered length.
+ if (length == 0) {
+ state = state.create(buffer, seed);
+ length = 64;
+ } else {
+ // Mix this chunk into the current state and bump length up by 64.
+ state.mix(buffer);
+ length += 64;
+ }
+ // Reset the buffer_ptr to the head of the buffer for the next chunk of
+ // data.
+ buffer_ptr = buffer;
+
+ // Try again to store into the buffer -- this cannot fail as we only
+ // store types smaller than the buffer.
+ if (!store_and_advance(buffer_ptr, buffer_end, data,
+ partial_store_size))
+ abort();
}
+ return buffer_ptr;
}
- // Add a range of bits from I to E.
- template<typename T>
- void addBits(const T *I, const T *E) {
- addBytes(reinterpret_cast<const char *>(I),
- reinterpret_cast<const char *>(E));
+#if defined(__has_feature) && __has_feature(__cxx_variadic_templates__)
+
+ /// \brief Recursive, variadic combining method.
+ ///
+ /// This function recurses through each argument, combining that argument
+ /// into a single hash.
+ template <typename T, typename ...Ts>
+ hash_code combine(size_t length, char *buffer_ptr, char *buffer_end,
+ const T &arg, const Ts &...args) {
+ buffer_ptr = combine_data(length, buffer_ptr, buffer_end, get_hashable_data(arg));
+
+ // Recurse to the next argument.
+ return combine(length, buffer_ptr, buffer_end, args...);
+ }
+
+#else
+ // Manually expanded recursive combining methods. See variadic above for
+ // documentation.
+
+ template <typename T1, typename T2, typename T3, typename T4, typename T5,
+ typename T6>
+ hash_code combine(size_t length, char *buffer_ptr, char *buffer_end,
+ const T1 &arg1, const T2 &arg2, const T3 &arg3,
+ const T4 &arg4, const T5 &arg5, const T6 &arg6) {
+ buffer_ptr = combine_data(length, buffer_ptr, buffer_end, get_hashable_data(arg1));
+ return combine(length, buffer_ptr, buffer_end, arg2, arg3, arg4, arg5, arg6);
+ }
+ template <typename T1, typename T2, typename T3, typename T4, typename T5>
+ hash_code combine(size_t length, char *buffer_ptr, char *buffer_end,
+ const T1 &arg1, const T2 &arg2, const T3 &arg3,
+ const T4 &arg4, const T5 &arg5) {
+ buffer_ptr = combine_data(length, buffer_ptr, buffer_end, get_hashable_data(arg1));
+ return combine(length, buffer_ptr, buffer_end, arg2, arg3, arg4, arg5);
+ }
+ template <typename T1, typename T2, typename T3, typename T4>
+ hash_code combine(size_t length, char *buffer_ptr, char *buffer_end,
+ const T1 &arg1, const T2 &arg2, const T3 &arg3,
+ const T4 &arg4) {
+ buffer_ptr = combine_data(length, buffer_ptr, buffer_end, get_hashable_data(arg1));
+ return combine(length, buffer_ptr, buffer_end, arg2, arg3, arg4);
+ }
+ template <typename T1, typename T2, typename T3>
+ hash_code combine(size_t length, char *buffer_ptr, char *buffer_end,
+ const T1 &arg1, const T2 &arg2, const T3 &arg3) {
+ buffer_ptr = combine_data(length, buffer_ptr, buffer_end, get_hashable_data(arg1));
+ return combine(length, buffer_ptr, buffer_end, arg2, arg3);
+ }
+ template <typename T1, typename T2>
+ hash_code combine(size_t length, char *buffer_ptr, char *buffer_end,
+ const T1 &arg1, const T2 &arg2) {
+ buffer_ptr = combine_data(length, buffer_ptr, buffer_end, get_hashable_data(arg1));
+ return combine(length, buffer_ptr, buffer_end, arg2);
+ }
+ template <typename T1>
+ hash_code combine(size_t length, char *buffer_ptr, char *buffer_end,
+ const T1 &arg1) {
+ buffer_ptr = combine_data(length, buffer_ptr, buffer_end, get_hashable_data(arg1));
+ return combine(length, buffer_ptr, buffer_end);
+ }
+
+#endif
+
+ /// \brief Base case for recursive, variadic combining.
+ ///
+ /// The base case when combining arguments recursively is reached when all
+ /// arguments have been handled. It flushes the remaining buffer and
+ /// constructs a hash_code.
+ hash_code combine(size_t length, char *buffer_ptr, char *buffer_end) {
+ // Check whether the entire set of values fit in the buffer. If so, we'll
+ // use the optimized short hashing routine and skip state entirely.
+ if (length == 0)
+ return hash_short(buffer, buffer_ptr - buffer, seed);
+
+ // Mix the final buffer, rotating it if we did a partial fill in order to
+ // simulate doing a mix of the last 64-bytes. That is how the algorithm
+ // works when we have a contiguous byte sequence, and we want to emulate
+ // that here.
+ std::rotate(buffer, buffer_ptr, buffer_end);
+
+ // Mix this chunk into the current state.
+ state.mix(buffer);
+ length += buffer_ptr - buffer;
+
+ return state.finalize(length);
}
};
-} // end namespace llvm
+} // namespace detail
+} // namespace hashing
+
+
+#if __has_feature(__cxx_variadic_templates__)
+
+/// \brief Combine values into a single hash_code.
+///
+/// This routine accepts a varying number of arguments of any type. It will
+/// attempt to combine them into a single hash_code. For user-defined types it
+/// attempts to call a \see hash_value overload (via ADL) for the type. For
+/// integer and pointer types it directly combines their data into the
+/// resulting hash_code.
+///
+/// The result is suitable for returning from a user's hash_value
+/// *implementation* for their user-defined type. Consumers of a type should
+/// *not* call this routine, they should instead call 'hash_value'.
+template <typename ...Ts> hash_code hash_combine(const Ts &...args) {
+ // Recursively hash each argument using a helper class.
+ ::llvm::hashing::detail::hash_combine_recursive_helper helper;
+ return helper.combine(0, helper.buffer, helper.buffer + 64, args...);
+}
+
+#else
+
+// What follows are manually exploded overloads for each argument width. See
+// the above variadic definition for documentation and specification.
+
+template <typename T1, typename T2, typename T3, typename T4, typename T5,
+ typename T6>
+hash_code hash_combine(const T1 &arg1, const T2 &arg2, const T3 &arg3,
+ const T4 &arg4, const T5 &arg5, const T6 &arg6) {
+ ::llvm::hashing::detail::hash_combine_recursive_helper helper;
+ return helper.combine(0, helper.buffer, helper.buffer + 64,
+ arg1, arg2, arg3, arg4, arg5, arg6);
+}
+template <typename T1, typename T2, typename T3, typename T4, typename T5>
+hash_code hash_combine(const T1 &arg1, const T2 &arg2, const T3 &arg3,
+ const T4 &arg4, const T5 &arg5) {
+ ::llvm::hashing::detail::hash_combine_recursive_helper helper;
+ return helper.combine(0, helper.buffer, helper.buffer + 64,
+ arg1, arg2, arg3, arg4, arg5);
+}
+template <typename T1, typename T2, typename T3, typename T4>
+hash_code hash_combine(const T1 &arg1, const T2 &arg2, const T3 &arg3,
+ const T4 &arg4) {
+ ::llvm::hashing::detail::hash_combine_recursive_helper helper;
+ return helper.combine(0, helper.buffer, helper.buffer + 64,
+ arg1, arg2, arg3, arg4);
+}
+template <typename T1, typename T2, typename T3>
+hash_code hash_combine(const T1 &arg1, const T2 &arg2, const T3 &arg3) {
+ ::llvm::hashing::detail::hash_combine_recursive_helper helper;
+ return helper.combine(0, helper.buffer, helper.buffer + 64, arg1, arg2, arg3);
+}
+template <typename T1, typename T2>
+hash_code hash_combine(const T1 &arg1, const T2 &arg2) {
+ ::llvm::hashing::detail::hash_combine_recursive_helper helper;
+ return helper.combine(0, helper.buffer, helper.buffer + 64, arg1, arg2);
+}
+template <typename T1>
+hash_code hash_combine(const T1 &arg1) {
+ ::llvm::hashing::detail::hash_combine_recursive_helper helper;
+ return helper.combine(0, helper.buffer, helper.buffer + 64, arg1);
+}
+
+#endif
+
+
+// Implementation details for implementations of hash_value overloads provided
+// here.
+namespace hashing {
+namespace detail {
+
+/// \brief Helper to hash the value of a single integer.
+///
+/// Overloads for smaller integer types are not provided to ensure consistent
+/// behavior in the presence of integral promotions. Essentially,
+/// "hash_value('4')" and "hash_value('0' + 4)" should be the same.
+inline hash_code hash_integer_value(uint64_t value) {
+ // Similar to hash_4to8_bytes but using a seed instead of length.
+ const uint64_t seed = get_execution_seed();
+ const char *s = reinterpret_cast<const char *>(&value);
+ const uint64_t a = fetch32(s);
+ return hash_16_bytes(seed + (a << 3), fetch32(s + 4));
+}
+
+} // namespace detail
+} // namespace hashing
+
+// Declared and documented above, but defined here so that any of the hashing
+// infrastructure is available.
+template <typename T>
+typename enable_if<is_integral_or_enum<T>, hash_code>::type
+hash_value(T value) {
+ return ::llvm::hashing::detail::hash_integer_value(value);
+}
+
+// Declared and documented above, but defined here so that any of the hashing
+// infrastructure is available.
+template <typename T> hash_code hash_value(const T *ptr) {
+ return ::llvm::hashing::detail::hash_integer_value(
+ reinterpret_cast<uintptr_t>(ptr));
+}
+
+// Declared and documented above, but defined here so that any of the hashing
+// infrastructure is available.
+template <typename T, typename U>
+hash_code hash_value(const std::pair<T, U> &arg) {
+ return hash_combine(arg.first, arg.second);
+}
+
+// Declared and documented above, but defined here so that any of the hashing
+// infrastructure is available.
+template <typename T>
+hash_code hash_value(const std::basic_string<T> &arg) {
+ return hash_combine_range(arg.begin(), arg.end());
+}
+
+} // namespace llvm
#endif
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