[libc++] Instantiate hash function externally (#127040)
This has multiple benefits:
- There is a single instance of our hash function, reducing object file
size
- The hash implementation isn't instantiated in every TU anymore,
reducing compile times
- Behind an ABI configuration macro it would be possible to salt the
hash
diff --git a/libcxx/include/__configuration/availability.h b/libcxx/include/__configuration/availability.h
index 261cf9c..7e2ad79 100644
--- a/libcxx/include/__configuration/availability.h
+++ b/libcxx/include/__configuration/availability.h
@@ -78,6 +78,9 @@
// in all versions of the library are available.
#if !_LIBCPP_HAS_VENDOR_AVAILABILITY_ANNOTATIONS
+# define _LIBCPP_INTRODUCED_IN_LLVM_21 1
+# define _LIBCPP_INTRODUCED_IN_LLVM_21_ATTRIBUTE /* nothing */
+
# define _LIBCPP_INTRODUCED_IN_LLVM_20 1
# define _LIBCPP_INTRODUCED_IN_LLVM_20_ATTRIBUTE /* nothing */
@@ -114,6 +117,11 @@
// clang-format off
+// LLVM 21
+// TODO: Fill this in
+# define _LIBCPP_INTRODUCED_IN_LLVM_21 0
+# define _LIBCPP_INTRODUCED_IN_LLVM_21_ATTRIBUTE __attribute__((unavailable))
+
// LLVM 20
// TODO: Fill this in
# define _LIBCPP_INTRODUCED_IN_LLVM_20 0
@@ -359,6 +367,11 @@
#define _LIBCPP_AVAILABILITY_HAS_FROM_CHARS_FLOATING_POINT _LIBCPP_INTRODUCED_IN_LLVM_20
#define _LIBCPP_AVAILABILITY_FROM_CHARS_FLOATING_POINT _LIBCPP_INTRODUCED_IN_LLVM_20_ATTRIBUTE
+// This controls whether `std::__hash_memory` is available in the dylib, which
+// is used for some `std::hash` specializations.
+#define _LIBCPP_AVAILABILITY_HAS_HASH_MEMORY _LIBCPP_INTRODUCED_IN_LLVM_21
+// No attribute, since we've had hash in the headers before
+
// Define availability attributes that depend on _LIBCPP_HAS_EXCEPTIONS.
// Those are defined in terms of the availability attributes above, and
// should not be vendor-specific.
diff --git a/libcxx/include/__functional/hash.h b/libcxx/include/__functional/hash.h
index df654c8..a191748 100644
--- a/libcxx/include/__functional/hash.h
+++ b/libcxx/include/__functional/hash.h
@@ -238,6 +238,14 @@
}
};
+#if _LIBCPP_AVAILABILITY_HAS_HASH_MEMORY
+[[__gnu__::__pure__]] _LIBCPP_EXPORTED_FROM_ABI size_t __hash_memory(_LIBCPP_NOESCAPE const void*, size_t) _NOEXCEPT;
+#else
+_LIBCPP_HIDE_FROM_ABI inline size_t __hash_memory(const void* __ptr, size_t __size) _NOEXCEPT {
+ return __murmur2_or_cityhash<size_t>()(__ptr, __size);
+}
+#endif
+
template <class _Tp, size_t = sizeof(_Tp) / sizeof(size_t)>
struct __scalar_hash;
@@ -277,7 +285,7 @@
} __s;
} __u;
__u.__t = __v;
- return __murmur2_or_cityhash<size_t>()(std::addressof(__u), sizeof(__u));
+ return std::__hash_memory(std::addressof(__u), sizeof(__u));
}
};
@@ -293,7 +301,7 @@
} __s;
} __u;
__u.__t = __v;
- return __murmur2_or_cityhash<size_t>()(std::addressof(__u), sizeof(__u));
+ return std::__hash_memory(std::addressof(__u), sizeof(__u));
}
};
@@ -310,7 +318,7 @@
} __s;
} __u;
__u.__t = __v;
- return __murmur2_or_cityhash<size_t>()(std::addressof(__u), sizeof(__u));
+ return std::__hash_memory(std::addressof(__u), sizeof(__u));
}
};
@@ -333,7 +341,7 @@
size_t __a;
} __u;
__u.__t = __v;
- return __murmur2_or_cityhash<size_t>()(std::addressof(__u), sizeof(__u));
+ return std::__hash_memory(std::addressof(__u), sizeof(__u));
}
};
diff --git a/libcxx/include/__string/char_traits.h b/libcxx/include/__string/char_traits.h
index 9574cde..29586bf 100644
--- a/libcxx/include/__string/char_traits.h
+++ b/libcxx/include/__string/char_traits.h
@@ -534,7 +534,7 @@
template <class _Ptr>
inline _LIBCPP_HIDE_FROM_ABI size_t __do_string_hash(_Ptr __p, _Ptr __e) {
typedef typename iterator_traits<_Ptr>::value_type value_type;
- return __murmur2_or_cityhash<size_t>()(__p, (__e - __p) * sizeof(value_type));
+ return std::__hash_memory(__p, (__e - __p) * sizeof(value_type));
}
_LIBCPP_END_NAMESPACE_STD
diff --git a/libcxx/lib/abi/CHANGELOG.TXT b/libcxx/lib/abi/CHANGELOG.TXT
index 2b490d0..bba9163 100644
--- a/libcxx/lib/abi/CHANGELOG.TXT
+++ b/libcxx/lib/abi/CHANGELOG.TXT
@@ -13,6 +13,21 @@
New entries should be added directly below the "Version" header.
------------
+Version 21.0
+------------
+
+* [libc++] Instantiate hash function externally
+
+ This has multiple benefits:
+ - There is a single instance of our hash function, reducing object file size
+ - The hash implementation isn't instantiated in every TU anymore, reducing compile times
+ - Behind an ABI configuration macro, it would be possible to salt the hash
+
+ All platforms
+ -------------
+ Symbol added: _ZNSt3__113__hash_memoryEPKvm
+
+------------
Version 20.0
------------
diff --git a/libcxx/lib/abi/arm64-apple-darwin.libcxxabi.v1.stable.exceptions.nonew.abilist b/libcxx/lib/abi/arm64-apple-darwin.libcxxabi.v1.stable.exceptions.nonew.abilist
index 7f6d1f3..24cf405 100644
--- a/libcxx/lib/abi/arm64-apple-darwin.libcxxabi.v1.stable.exceptions.nonew.abilist
+++ b/libcxx/lib/abi/arm64-apple-darwin.libcxxabi.v1.stable.exceptions.nonew.abilist
@@ -1305,6 +1305,7 @@
{'is_defined': True, 'name': '__ZNSt3__113shared_futureIvED1Ev', 'type': 'FUNC'}
{'is_defined': True, 'name': '__ZNSt3__113shared_futureIvED2Ev', 'type': 'FUNC'}
{'is_defined': True, 'name': '__ZNSt3__113shared_futureIvEaSERKS1_', 'type': 'FUNC'}
+{'is_defined': True, 'name': '__ZNSt3__113__hash_memoryEPKvm', 'type': 'FUNC'}
{'is_defined': True, 'name': '__ZNSt3__114__num_get_base10__get_baseERNS_8ios_baseE', 'type': 'FUNC'}
{'is_defined': True, 'name': '__ZNSt3__114__num_get_base5__srcE', 'size': 0, 'type': 'OBJECT'}
{'is_defined': True, 'name': '__ZNSt3__114__num_put_base12__format_intEPcPKcbj', 'type': 'FUNC'}
diff --git a/libcxx/lib/abi/i686-linux-android21.libcxxabi.v1.stable.exceptions.nonew.abilist b/libcxx/lib/abi/i686-linux-android21.libcxxabi.v1.stable.exceptions.nonew.abilist
index b38cedb..4b98b19b 100644
--- a/libcxx/lib/abi/i686-linux-android21.libcxxabi.v1.stable.exceptions.nonew.abilist
+++ b/libcxx/lib/abi/i686-linux-android21.libcxxabi.v1.stable.exceptions.nonew.abilist
@@ -941,6 +941,7 @@
{'is_defined': True, 'name': '_ZNSt6__ndk113shared_futureIvED1Ev', 'type': 'FUNC'}
{'is_defined': True, 'name': '_ZNSt6__ndk113shared_futureIvED2Ev', 'type': 'FUNC'}
{'is_defined': True, 'name': '_ZNSt6__ndk113shared_futureIvEaSERKS1_', 'type': 'FUNC'}
+{'is_defined': True, 'name': '_ZNSt6__ndk113__hash_memoryEPKvj', 'type': 'FUNC'}
{'is_defined': True, 'name': '_ZNSt6__ndk114__num_get_base10__get_baseERNS_8ios_baseE', 'type': 'FUNC'}
{'is_defined': True, 'name': '_ZNSt6__ndk114__num_get_base5__srcE', 'size': 33, 'type': 'OBJECT'}
{'is_defined': True, 'name': '_ZNSt6__ndk114__num_put_base12__format_intEPcPKcbj', 'type': 'FUNC'}
diff --git a/libcxx/lib/abi/powerpc-ibm-aix.libcxxabi.v1.stable.exceptions.nonew.abilist b/libcxx/lib/abi/powerpc-ibm-aix.libcxxabi.v1.stable.exceptions.nonew.abilist
index 9f299d6..368ab7c 100644
--- a/libcxx/lib/abi/powerpc-ibm-aix.libcxxabi.v1.stable.exceptions.nonew.abilist
+++ b/libcxx/lib/abi/powerpc-ibm-aix.libcxxabi.v1.stable.exceptions.nonew.abilist
@@ -418,6 +418,7 @@
{'import_export': 'EXP', 'is_defined': True, 'name': '_ZNSt3__113shared_futureIvED1Ev', 'storage_mapping_class': 'DS', 'type': 'FUNC'}
{'import_export': 'EXP', 'is_defined': True, 'name': '_ZNSt3__113shared_futureIvED2Ev', 'storage_mapping_class': 'DS', 'type': 'FUNC'}
{'import_export': 'EXP', 'is_defined': True, 'name': '_ZNSt3__113shared_futureIvEaSERKS1_', 'storage_mapping_class': 'DS', 'type': 'FUNC'}
+{'import_export': 'EXP', 'is_defined': True, 'name': '_ZNSt3__113__hash_memoryEPKvm', 'storage_mapping_class': 'DS', 'type': 'FUNC'}
{'import_export': 'EXP', 'is_defined': True, 'name': '_ZNSt3__114__num_get_base10__get_baseERNS_8ios_baseE', 'storage_mapping_class': 'DS', 'type': 'FUNC'}
{'import_export': 'EXP', 'is_defined': True, 'name': '_ZNSt3__114__num_get_base5__srcE', 'storage_mapping_class': 'RO', 'type': 'OBJECT'}
{'import_export': 'EXP', 'is_defined': True, 'name': '_ZNSt3__114__num_put_base12__format_intEPcPKcbj', 'storage_mapping_class': 'DS', 'type': 'FUNC'}
diff --git a/libcxx/lib/abi/powerpc64-ibm-aix.libcxxabi.v1.stable.exceptions.nonew.abilist b/libcxx/lib/abi/powerpc64-ibm-aix.libcxxabi.v1.stable.exceptions.nonew.abilist
index 3a071b9..642fcd5 100644
--- a/libcxx/lib/abi/powerpc64-ibm-aix.libcxxabi.v1.stable.exceptions.nonew.abilist
+++ b/libcxx/lib/abi/powerpc64-ibm-aix.libcxxabi.v1.stable.exceptions.nonew.abilist
@@ -418,6 +418,7 @@
{'import_export': 'EXP', 'is_defined': True, 'name': '_ZNSt3__113shared_futureIvED1Ev', 'storage_mapping_class': 'DS', 'type': 'FUNC'}
{'import_export': 'EXP', 'is_defined': True, 'name': '_ZNSt3__113shared_futureIvED2Ev', 'storage_mapping_class': 'DS', 'type': 'FUNC'}
{'import_export': 'EXP', 'is_defined': True, 'name': '_ZNSt3__113shared_futureIvEaSERKS1_', 'storage_mapping_class': 'DS', 'type': 'FUNC'}
+{'import_export': 'EXP', 'is_defined': True, 'name': '_ZNSt3__113__hash_memoryEPKvm', 'storage_mapping_class': 'DS', 'type': 'FUNC'}
{'import_export': 'EXP', 'is_defined': True, 'name': '_ZNSt3__114__num_get_base10__get_baseERNS_8ios_baseE', 'storage_mapping_class': 'DS', 'type': 'FUNC'}
{'import_export': 'EXP', 'is_defined': True, 'name': '_ZNSt3__114__num_get_base5__srcE', 'storage_mapping_class': 'RO', 'type': 'OBJECT'}
{'import_export': 'EXP', 'is_defined': True, 'name': '_ZNSt3__114__num_put_base12__format_intEPcPKcbj', 'storage_mapping_class': 'DS', 'type': 'FUNC'}
diff --git a/libcxx/lib/abi/x86_64-apple-darwin.libcxxabi.v1.stable.exceptions.nonew.abilist b/libcxx/lib/abi/x86_64-apple-darwin.libcxxabi.v1.stable.exceptions.nonew.abilist
index 39e1aae..6571f98 100644
--- a/libcxx/lib/abi/x86_64-apple-darwin.libcxxabi.v1.stable.exceptions.nonew.abilist
+++ b/libcxx/lib/abi/x86_64-apple-darwin.libcxxabi.v1.stable.exceptions.nonew.abilist
@@ -1305,6 +1305,7 @@
{'is_defined': True, 'name': '__ZNSt3__113shared_futureIvED1Ev', 'type': 'FUNC'}
{'is_defined': True, 'name': '__ZNSt3__113shared_futureIvED2Ev', 'type': 'FUNC'}
{'is_defined': True, 'name': '__ZNSt3__113shared_futureIvEaSERKS1_', 'type': 'FUNC'}
+{'is_defined': True, 'name': '__ZNSt3__113__hash_memoryEPKvm', 'type': 'FUNC'}
{'is_defined': True, 'name': '__ZNSt3__114__num_get_base10__get_baseERNS_8ios_baseE', 'type': 'FUNC'}
{'is_defined': True, 'name': '__ZNSt3__114__num_get_base5__srcE', 'size': 0, 'type': 'OBJECT'}
{'is_defined': True, 'name': '__ZNSt3__114__num_put_base12__format_intEPcPKcbj', 'type': 'FUNC'}
diff --git a/libcxx/lib/abi/x86_64-linux-android21.libcxxabi.v1.stable.exceptions.nonew.abilist b/libcxx/lib/abi/x86_64-linux-android21.libcxxabi.v1.stable.exceptions.nonew.abilist
index 5c8329c..c03b4f3 100644
--- a/libcxx/lib/abi/x86_64-linux-android21.libcxxabi.v1.stable.exceptions.nonew.abilist
+++ b/libcxx/lib/abi/x86_64-linux-android21.libcxxabi.v1.stable.exceptions.nonew.abilist
@@ -941,6 +941,7 @@
{'is_defined': True, 'name': '_ZNSt6__ndk113shared_futureIvED1Ev', 'type': 'FUNC'}
{'is_defined': True, 'name': '_ZNSt6__ndk113shared_futureIvED2Ev', 'type': 'FUNC'}
{'is_defined': True, 'name': '_ZNSt6__ndk113shared_futureIvEaSERKS1_', 'type': 'FUNC'}
+{'is_defined': True, 'name': '_ZNSt6__ndk113__hash_memoryEPKvm', 'type': 'FUNC'}
{'is_defined': True, 'name': '_ZNSt6__ndk114__num_get_base10__get_baseERNS_8ios_baseE', 'type': 'FUNC'}
{'is_defined': True, 'name': '_ZNSt6__ndk114__num_get_base5__srcE', 'size': 33, 'type': 'OBJECT'}
{'is_defined': True, 'name': '_ZNSt6__ndk114__num_put_base12__format_intEPcPKcbj', 'type': 'FUNC'}
diff --git a/libcxx/lib/abi/x86_64-unknown-freebsd.libcxxabi.v1.stable.exceptions.nonew.abilist b/libcxx/lib/abi/x86_64-unknown-freebsd.libcxxabi.v1.stable.exceptions.nonew.abilist
index a67dc76..e1579e2 100644
--- a/libcxx/lib/abi/x86_64-unknown-freebsd.libcxxabi.v1.stable.exceptions.nonew.abilist
+++ b/libcxx/lib/abi/x86_64-unknown-freebsd.libcxxabi.v1.stable.exceptions.nonew.abilist
@@ -956,6 +956,7 @@
{'is_defined': True, 'name': '_ZNSt3__113shared_futureIvED1Ev', 'type': 'FUNC'}
{'is_defined': True, 'name': '_ZNSt3__113shared_futureIvED2Ev', 'type': 'FUNC'}
{'is_defined': True, 'name': '_ZNSt3__113shared_futureIvEaSERKS1_', 'type': 'FUNC'}
+{'is_defined': True, 'name': '_ZNSt3__113__hash_memoryEPKvm', 'type': 'FUNC'}
{'is_defined': True, 'name': '_ZNSt3__114__num_get_base10__get_baseERNS_8ios_baseE', 'type': 'FUNC'}
{'is_defined': True, 'name': '_ZNSt3__114__num_get_base5__srcE', 'size': 33, 'type': 'OBJECT'}
{'is_defined': True, 'name': '_ZNSt3__114__num_put_base12__format_intEPcPKcbj', 'type': 'FUNC'}
diff --git a/libcxx/lib/abi/x86_64-unknown-linux-gnu.libcxxabi.v1.stable.exceptions.nonew.abilist b/libcxx/lib/abi/x86_64-unknown-linux-gnu.libcxxabi.v1.stable.exceptions.nonew.abilist
index 3aa9e50..3a4fb06 100644
--- a/libcxx/lib/abi/x86_64-unknown-linux-gnu.libcxxabi.v1.stable.exceptions.nonew.abilist
+++ b/libcxx/lib/abi/x86_64-unknown-linux-gnu.libcxxabi.v1.stable.exceptions.nonew.abilist
@@ -954,6 +954,7 @@
{'is_defined': True, 'name': '_ZNSt3__113shared_futureIvED1Ev', 'type': 'FUNC'}
{'is_defined': True, 'name': '_ZNSt3__113shared_futureIvED2Ev', 'type': 'FUNC'}
{'is_defined': True, 'name': '_ZNSt3__113shared_futureIvEaSERKS1_', 'type': 'FUNC'}
+{'is_defined': True, 'name': '_ZNSt3__113__hash_memoryEPKvm', 'type': 'FUNC'}
{'is_defined': True, 'name': '_ZNSt3__114__num_get_base10__get_baseERNS_8ios_baseE', 'type': 'FUNC'}
{'is_defined': True, 'name': '_ZNSt3__114__num_get_base5__srcE', 'size': 33, 'type': 'OBJECT'}
{'is_defined': True, 'name': '_ZNSt3__114__num_put_base12__format_intEPcPKcbj', 'type': 'FUNC'}
diff --git a/libcxx/lib/abi/x86_64-unknown-linux-gnu.libcxxabi.v1.stable.noexceptions.nonew.abilist b/libcxx/lib/abi/x86_64-unknown-linux-gnu.libcxxabi.v1.stable.noexceptions.nonew.abilist
index 74681c2..e5ec142 100644
--- a/libcxx/lib/abi/x86_64-unknown-linux-gnu.libcxxabi.v1.stable.noexceptions.nonew.abilist
+++ b/libcxx/lib/abi/x86_64-unknown-linux-gnu.libcxxabi.v1.stable.noexceptions.nonew.abilist
@@ -924,6 +924,7 @@
{'is_defined': True, 'name': '_ZNSt3__113random_deviceclEv', 'type': 'FUNC'}
{'is_defined': True, 'name': '_ZNSt3__113shared_futureIvED1Ev', 'type': 'FUNC'}
{'is_defined': True, 'name': '_ZNSt3__113shared_futureIvED2Ev', 'type': 'FUNC'}
+{'is_defined': True, 'name': '_ZNSt3__113__hash_memoryEPKvm', 'type': 'FUNC'}
{'is_defined': True, 'name': '_ZNSt3__113shared_futureIvEaSERKS1_', 'type': 'FUNC'}
{'is_defined': True, 'name': '_ZNSt3__114__num_get_base10__get_baseERNS_8ios_baseE', 'type': 'FUNC'}
{'is_defined': True, 'name': '_ZNSt3__114__num_get_base5__srcE', 'size': 33, 'type': 'OBJECT'}
diff --git a/libcxx/src/functional.cpp b/libcxx/src/functional.cpp
index ef53e3e..cf585c2 100644
--- a/libcxx/src/functional.cpp
+++ b/libcxx/src/functional.cpp
@@ -16,4 +16,8 @@
const char* bad_function_call::what() const noexcept { return "std::bad_function_call"; }
#endif
+size_t __hash_memory(_LIBCPP_NOESCAPE const void* ptr, size_t size) noexcept {
+ return __murmur2_or_cityhash<size_t>()(ptr, size);
+}
+
_LIBCPP_END_NAMESPACE_STD
