[libc-commits] [libc] 917e0d9 - [libc][NFC] Rework generic memory operations
Guillaume Chatelet via libc-commits
libc-commits at lists.llvm.org
Wed Apr 5 11:48:13 PDT 2023
Author: Guillaume Chatelet
Date: 2023-04-05T18:48:04Z
New Revision: 917e0d9c42c5aee3a90105fbbf108485c5c7e657
URL: https://github.com/llvm/llvm-project/commit/917e0d9c42c5aee3a90105fbbf108485c5c7e657
DIFF: https://github.com/llvm/llvm-project/commit/917e0d9c42c5aee3a90105fbbf108485c5c7e657.diff
LOG: [libc][NFC] Rework generic memory operations
Added:
Modified:
libc/src/string/memory_utils/op_generic.h
Removed:
################################################################################
diff --git a/libc/src/string/memory_utils/op_generic.h b/libc/src/string/memory_utils/op_generic.h
index 03c6cab46e870..02d90a1b29296 100644
--- a/libc/src/string/memory_utils/op_generic.h
+++ b/libc/src/string/memory_utils/op_generic.h
@@ -35,35 +35,11 @@
namespace __llvm_libc::generic {
-// CTPair and CTMap below implement a compile time map.
-// This is useful to map from a Size to a type handling this size.
-//
-// Example usage:
-// using MyMap = CTMap<CTPair<1, uint8_t>,
-// CTPair<2, uint16_t>,
-// >;
-// ...
-// using UInt8T = MyMap::find_type<1>;
-template <size_t I, typename T> struct CTPair {
- using type = T;
- LIBC_INLINE static CTPair get_pair(cpp::integral_constant<size_t, I>) {
- return {};
- }
-};
-template <typename... Pairs> struct CTMap : public Pairs... {
- using Pairs::get_pair...;
- template <size_t I>
- using find_type =
- typename decltype(get_pair(cpp::integral_constant<size_t, I>{}))::type;
-};
-
-// Helper to test if a type is void.
-template <typename T> inline constexpr bool is_void_v = cpp::is_same_v<T, void>;
-
-// Implements load, store and splat for unsigned integral types.
+// Implements generic load, store, splat and set for unsigned integral types.
template <typename T> struct ScalarType {
+ static_assert(cpp::is_integral_v<T> && !cpp::is_signed_v<T>);
using Type = T;
- static_assert(cpp::is_integral_v<Type> && !cpp::is_signed_v<Type>);
+ static constexpr size_t SIZE = sizeof(Type);
LIBC_INLINE static Type load(CPtr src) {
return ::__llvm_libc::load<Type>(src);
@@ -74,6 +50,9 @@ template <typename T> struct ScalarType {
LIBC_INLINE static Type splat(uint8_t value) {
return Type(~0) / Type(0xFF) * Type(value);
}
+ LIBC_INLINE static void set(Ptr dst, uint8_t value) {
+ store(dst, splat(value));
+ }
};
// GCC can only take literals as __vector_size__ argument so we have to use
@@ -101,9 +80,10 @@ template <> struct VectorValueType<64> {
using type = uint8_t __attribute__((__vector_size__(64)));
};
-// Implements load, store and splat for vector types.
+// Implements generic load, store, splat and set for vector types.
template <size_t Size> struct VectorType {
using Type = typename VectorValueType<Size>::type;
+ static constexpr size_t SIZE = Size;
LIBC_INLINE static Type load(CPtr src) {
return ::__llvm_libc::load<Type>(src);
}
@@ -117,35 +97,17 @@ template <size_t Size> struct VectorType {
Out[i] = static_cast<uint8_t>(value);
return Out;
}
+ LIBC_INLINE static void set(Ptr dst, uint8_t value) {
+ store(dst, splat(value));
+ }
};
-static_assert((UINTPTR_MAX == 4294967295U) ||
- (UINTPTR_MAX == 18446744073709551615UL),
- "We currently only support 32- or 64-bit platforms");
-
-#if defined(LIBC_TARGET_ARCH_IS_X86_64) || defined(LIBC_TARGET_ARCH_IS_AARCH64)
-#define LLVM_LIBC_HAS_UINT64
-#endif
-
-// Map from sizes to structures offering static load, store and splat methods.
-// Note: On platforms lacking vector support, we use the ArrayType below and
-// decompose the operation in smaller pieces.
-using NativeTypeMap =
- CTMap<CTPair<1, ScalarType<uint8_t>>, //
- CTPair<2, ScalarType<uint16_t>>, //
- CTPair<4, ScalarType<uint32_t>>, //
-#if defined(LLVM_LIBC_HAS_UINT64)
- CTPair<8, ScalarType<uint64_t>>, // Not available on 32bit
-#endif //
- CTPair<16, VectorType<16>>, //
- CTPair<32, VectorType<32>>, //
- CTPair<64, VectorType<64>>>;
-
-// Implements load, store and splat for sizes not natively supported by the
+// Implements load, store and set for sizes not natively supported by the
// platform. SubType is either ScalarType or VectorType.
template <typename SubType, size_t ArraySize> struct ArrayType {
using Type = cpp::array<typename SubType::Type, ArraySize>;
- static constexpr size_t SizeOfElement = sizeof(typename SubType::Type);
+ static constexpr size_t SizeOfElement = SubType::SIZE;
+ static constexpr size_t SIZE = SizeOfElement * ArraySize;
LIBC_INLINE static Type load(CPtr src) {
Type Value;
for (size_t I = 0; I < ArraySize; ++I)
@@ -156,27 +118,106 @@ template <typename SubType, size_t ArraySize> struct ArrayType {
for (size_t I = 0; I < ArraySize; ++I)
SubType::store(dst + (I * SizeOfElement), Value[I]);
}
- LIBC_INLINE static Type splat(uint8_t value) {
- Type Out;
+ LIBC_INLINE static void set(Ptr dst, uint8_t value) {
+ const auto Splat = SubType::splat(value);
for (size_t I = 0; I < ArraySize; ++I)
- Out[I] = SubType::splat(value);
- return Out;
+ SubType::store(dst + (I * SizeOfElement), Splat);
}
};
-// Checks whether we should use an ArrayType.
+static_assert((UINTPTR_MAX == 4294967295U) ||
+ (UINTPTR_MAX == 18446744073709551615UL),
+ "We currently only support 32- or 64-bit platforms");
+
+#if defined(LIBC_TARGET_ARCH_IS_X86_64) || defined(LIBC_TARGET_ARCH_IS_AARCH64)
+#define LLVM_LIBC_HAS_UINT64
+#endif
+
+namespace details {
+// Checks that each type's SIZE is sorted in strictly decreasing order.
+// i.e. First::SIZE > Second::SIZE > ... > Last::SIZE
+template <typename First, typename Second, typename... Next>
+constexpr bool is_decreasing_size() {
+ if constexpr (sizeof...(Next) > 0) {
+ return (First::SIZE > Second::SIZE) &&
+ is_decreasing_size<Second, Next...>();
+ } else {
+ return First::SIZE > Second::SIZE;
+ }
+}
+
+// Helper to test if a type is void.
+template <typename T> inline constexpr bool is_void_v = cpp::is_same_v<T, void>;
+
+} // namespace details
+
+// 'SupportedTypes' holds a list of natively supported types.
+// The types are instanciations of ScalarType or VectorType.
+// They should be ordered in strictly decreasing order.
+// The 'TypeFor<Size>' type retrieves is the largest supported type that can
+// handle 'Size' bytes. e.g.
+//
+// using ST = SupportedTypes<ScalarType<uint16_t>, ScalarType<uint8_t>>;
+// using Type = ST::TypeFor<10>;
+// static_assert(cpp:is_same_v<Type, ScalarType<uint16_t>>);
+template <typename First, typename Second, typename... Next>
+struct SupportedTypes {
+ static_assert(details::is_decreasing_size<First, Second, Next...>());
+ using MaxType = First;
+
+ template <size_t Size>
+ using TypeFor = cpp::conditional_t<
+ (Size >= First::SIZE), First,
+ typename SupportedTypes<Second, Next...>::template TypeFor<Size>>;
+};
+
+template <typename First, typename Second>
+struct SupportedTypes<First, Second> {
+ static_assert(details::is_decreasing_size<First, Second>());
+ using MaxType = First;
+
+ template <size_t Size>
+ using TypeFor = cpp::conditional_t<
+ (Size >= First::SIZE), First,
+ cpp::conditional_t<(Size >= Second::SIZE), Second, void>>;
+};
+
+// Map from sizes to structures offering static load, store and splat methods.
+// Note: On platforms lacking vector support, we use the ArrayType below and
+// decompose the operation in smaller pieces.
+
+// Lists a generic native types to use for Memset and Memmove operations.
+// TODO: Inject the native types within Memset and Memmove depending on the
+// target architectures and derive MaxSize from it.
+using NativeTypeMap =
+ SupportedTypes<VectorType<64>, //
+ VectorType<32>, //
+ VectorType<16>,
+#if defined(LLVM_LIBC_HAS_UINT64)
+ ScalarType<uint64_t>, // Not available on 32bit
+#endif
+ ScalarType<uint32_t>, //
+ ScalarType<uint16_t>, //
+ ScalarType<uint8_t>>;
+
+namespace details {
+
+// In case the 'Size' is not supported we can fall back to a sequence of smaller
+// operations using the largest natively supported type.
template <size_t Size, size_t MaxSize> static constexpr bool useArrayType() {
return (Size > MaxSize) && ((Size % MaxSize) == 0) &&
- !is_void_v<NativeTypeMap::find_type<MaxSize>>;
+ !details::is_void_v<NativeTypeMap::TypeFor<MaxSize>>;
}
-// Compute the type to handle an operation of Size bytes knowing that the
+// Compute the type to handle an operation of 'Size' bytes knowing that the
// underlying platform only support native types up to MaxSize bytes.
template <size_t Size, size_t MaxSize>
using getTypeFor = cpp::conditional_t<
useArrayType<Size, MaxSize>(),
- ArrayType<NativeTypeMap::find_type<MaxSize>, Size / MaxSize>,
- NativeTypeMap::find_type<Size>>;
+ ArrayType<NativeTypeMap::TypeFor<MaxSize>, Size / MaxSize>,
+ NativeTypeMap::TypeFor<Size>>;
+
+} // namespace details
///////////////////////////////////////////////////////////////////////////////
// Memcpy
@@ -201,11 +242,11 @@ template <size_t Size, size_t MaxSize> struct Memset {
Memset<1, MaxSize>::block(dst + 2, value);
Memset<2, MaxSize>::block(dst, value);
} else {
- using T = getTypeFor<Size, MaxSize>;
- if constexpr (is_void_v<T>) {
+ using T = details::getTypeFor<Size, MaxSize>;
+ if constexpr (details::is_void_v<T>) {
deferred_static_assert("Unimplemented Size");
} else {
- T::store(dst, T::splat(value));
+ T::set(dst, value);
}
}
}
@@ -230,147 +271,17 @@ template <size_t Size, size_t MaxSize> struct Memset {
}
};
-///////////////////////////////////////////////////////////////////////////////
-// Bcmp
-///////////////////////////////////////////////////////////////////////////////
-template <size_t Size> struct Bcmp {
- static constexpr size_t SIZE = Size;
- static constexpr size_t MaxSize = LLVM_LIBC_IS_DEFINED(LLVM_LIBC_HAS_UINT64)
- ? sizeof(uint64_t)
- : sizeof(uint32_t);
-
- template <typename T> LIBC_INLINE static uint32_t load_xor(CPtr p1, CPtr p2) {
- return load<T>(p1) ^ load<T>(p2);
- }
-
- template <typename T>
- LIBC_INLINE static uint32_t load_not_equal(CPtr p1, CPtr p2) {
- return load<T>(p1) != load<T>(p2);
- }
-
- LIBC_INLINE static BcmpReturnType block(CPtr p1, CPtr p2) {
- if constexpr (Size == 1) {
- return load_xor<uint8_t>(p1, p2);
- } else if constexpr (Size == 2) {
- return load_xor<uint16_t>(p1, p2);
- } else if constexpr (Size == 4) {
- return load_xor<uint32_t>(p1, p2);
- } else if constexpr (Size == 8) {
- return load_not_equal<uint64_t>(p1, p2);
- } else if constexpr (useArrayType<Size, MaxSize>()) {
- for (size_t offset = 0; offset < Size; offset += MaxSize)
- if (auto value = Bcmp<MaxSize>::block(p1 + offset, p2 + offset))
- return value;
- } else {
- deferred_static_assert("Unimplemented Size");
- }
- return BcmpReturnType::ZERO();
- }
-
- LIBC_INLINE static BcmpReturnType tail(CPtr p1, CPtr p2, size_t count) {
- return block(p1 + count - SIZE, p2 + count - SIZE);
- }
-
- LIBC_INLINE static BcmpReturnType head_tail(CPtr p1, CPtr p2, size_t count) {
- return block(p1, p2) | tail(p1, p2, count);
- }
-
- LIBC_INLINE static BcmpReturnType loop_and_tail(CPtr p1, CPtr p2,
- size_t count) {
- static_assert(Size > 1, "a loop of size 1 does not need tail");
- size_t offset = 0;
- do {
- if (auto value = block(p1 + offset, p2 + offset))
- return value;
- offset += SIZE;
- } while (offset < count - SIZE);
- return tail(p1, p2, count);
- }
-};
-
-///////////////////////////////////////////////////////////////////////////////
-// Memcmp
-///////////////////////////////////////////////////////////////////////////////
-template <size_t Size> struct Memcmp {
- static constexpr size_t SIZE = Size;
- static constexpr size_t MaxSize = LLVM_LIBC_IS_DEFINED(LLVM_LIBC_HAS_UINT64)
- ? sizeof(uint64_t)
- : sizeof(uint32_t);
-
- template <typename T> LIBC_INLINE static T load_be(CPtr ptr) {
- return Endian::to_big_endian(load<T>(ptr));
- }
-
- template <typename T>
- LIBC_INLINE static MemcmpReturnType load_be_
diff (CPtr p1, CPtr p2) {
- return load_be<T>(p1) - load_be<T>(p2);
- }
-
- template <typename T>
- LIBC_INLINE static MemcmpReturnType load_be_cmp(CPtr p1, CPtr p2) {
- const auto la = load_be<T>(p1);
- const auto lb = load_be<T>(p2);
- return la > lb ? 1 : la < lb ? -1 : 0;
- }
-
- LIBC_INLINE static MemcmpReturnType block(CPtr p1, CPtr p2) {
- if constexpr (Size == 1) {
- return load_be_
diff <uint8_t>(p1, p2);
- } else if constexpr (Size == 2) {
- return load_be_
diff <uint16_t>(p1, p2);
- } else if constexpr (Size == 4) {
- return load_be_cmp<uint32_t>(p1, p2);
- } else if constexpr (Size == 8) {
- return load_be_cmp<uint64_t>(p1, p2);
- } else if constexpr (useArrayType<Size, MaxSize>()) {
- for (size_t offset = 0; offset < Size; offset += MaxSize)
- if (Bcmp<MaxSize>::block(p1 + offset, p2 + offset))
- return Memcmp<MaxSize>::block(p1 + offset, p2 + offset);
- return MemcmpReturnType::ZERO();
- } else if constexpr (Size == 3) {
- if (auto value = Memcmp<2>::block(p1, p2))
- return value;
- return Memcmp<1>::block(p1 + 2, p2 + 2);
- } else {
- deferred_static_assert("Unimplemented Size");
- }
- }
-
- LIBC_INLINE static MemcmpReturnType tail(CPtr p1, CPtr p2, size_t count) {
- return block(p1 + count - SIZE, p2 + count - SIZE);
- }
-
- LIBC_INLINE static MemcmpReturnType head_tail(CPtr p1, CPtr p2,
- size_t count) {
- if (auto value = block(p1, p2))
- return value;
- return tail(p1, p2, count);
- }
-
- LIBC_INLINE static MemcmpReturnType loop_and_tail(CPtr p1, CPtr p2,
- size_t count) {
- static_assert(Size > 1, "a loop of size 1 does not need tail");
- size_t offset = 0;
- do {
- if (auto value = block(p1 + offset, p2 + offset))
- return value;
- offset += SIZE;
- } while (offset < count - SIZE);
- return tail(p1, p2, count);
- }
-};
-
///////////////////////////////////////////////////////////////////////////////
// Memmove
///////////////////////////////////////////////////////////////////////////////
template <size_t Size, size_t MaxSize> struct Memmove {
static_assert(is_power2(MaxSize));
- using T = getTypeFor<Size, MaxSize>;
+ using T = details::getTypeFor<Size, MaxSize>;
static constexpr size_t SIZE = Size;
LIBC_INLINE static void block(Ptr dst, CPtr src) {
- if constexpr (is_void_v<T>) {
+ if constexpr (details::is_void_v<T>) {
deferred_static_assert("Unimplemented Size");
} else {
T::store(dst, T::load(src));
@@ -379,7 +290,7 @@ template <size_t Size, size_t MaxSize> struct Memmove {
LIBC_INLINE static void head_tail(Ptr dst, CPtr src, size_t count) {
const size_t offset = count - Size;
- if constexpr (is_void_v<T>) {
+ if constexpr (details::is_void_v<T>) {
deferred_static_assert("Unimplemented Size");
} else {
// The load and store operations can be performed in any order as long as
@@ -506,6 +417,137 @@ template <size_t Size, size_t MaxSize> struct Memmove {
}
};
+///////////////////////////////////////////////////////////////////////////////
+// Bcmp
+///////////////////////////////////////////////////////////////////////////////
+template <size_t Size> struct Bcmp {
+ static constexpr size_t SIZE = Size;
+ static constexpr size_t MaxSize = LLVM_LIBC_IS_DEFINED(LLVM_LIBC_HAS_UINT64)
+ ? sizeof(uint64_t)
+ : sizeof(uint32_t);
+
+ template <typename T> LIBC_INLINE static uint32_t load_xor(CPtr p1, CPtr p2) {
+ static_assert(sizeof(T) <= sizeof(uint32_t));
+ return load<T>(p1) ^ load<T>(p2);
+ }
+
+ template <typename T>
+ LIBC_INLINE static uint32_t load_not_equal(CPtr p1, CPtr p2) {
+ return load<T>(p1) != load<T>(p2);
+ }
+
+ LIBC_INLINE static BcmpReturnType block(CPtr p1, CPtr p2) {
+ if constexpr (Size == 1) {
+ return load_xor<uint8_t>(p1, p2);
+ } else if constexpr (Size == 2) {
+ return load_xor<uint16_t>(p1, p2);
+ } else if constexpr (Size == 4) {
+ return load_xor<uint32_t>(p1, p2);
+ } else if constexpr (Size == 8) {
+ return load_not_equal<uint64_t>(p1, p2);
+ } else if constexpr (details::useArrayType<Size, MaxSize>()) {
+ for (size_t offset = 0; offset < Size; offset += MaxSize)
+ if (auto value = Bcmp<MaxSize>::block(p1 + offset, p2 + offset))
+ return value;
+ } else {
+ deferred_static_assert("Unimplemented Size");
+ }
+ return BcmpReturnType::ZERO();
+ }
+
+ LIBC_INLINE static BcmpReturnType tail(CPtr p1, CPtr p2, size_t count) {
+ return block(p1 + count - SIZE, p2 + count - SIZE);
+ }
+
+ LIBC_INLINE static BcmpReturnType head_tail(CPtr p1, CPtr p2, size_t count) {
+ return block(p1, p2) | tail(p1, p2, count);
+ }
+
+ LIBC_INLINE static BcmpReturnType loop_and_tail(CPtr p1, CPtr p2,
+ size_t count) {
+ static_assert(Size > 1, "a loop of size 1 does not need tail");
+ size_t offset = 0;
+ do {
+ if (auto value = block(p1 + offset, p2 + offset))
+ return value;
+ offset += SIZE;
+ } while (offset < count - SIZE);
+ return tail(p1, p2, count);
+ }
+};
+
+///////////////////////////////////////////////////////////////////////////////
+// Memcmp
+///////////////////////////////////////////////////////////////////////////////
+template <size_t Size> struct Memcmp {
+ static constexpr size_t SIZE = Size;
+ static constexpr size_t MaxSize = LLVM_LIBC_IS_DEFINED(LLVM_LIBC_HAS_UINT64)
+ ? sizeof(uint64_t)
+ : sizeof(uint32_t);
+
+ template <typename T> LIBC_INLINE static T load_be(CPtr ptr) {
+ return Endian::to_big_endian(load<T>(ptr));
+ }
+
+ template <typename T>
+ LIBC_INLINE static MemcmpReturnType load_be_
diff (CPtr p1, CPtr p2) {
+ return load_be<T>(p1) - load_be<T>(p2);
+ }
+
+ template <typename T>
+ LIBC_INLINE static MemcmpReturnType load_be_cmp(CPtr p1, CPtr p2) {
+ const auto la = load_be<T>(p1);
+ const auto lb = load_be<T>(p2);
+ return la > lb ? 1 : la < lb ? -1 : 0;
+ }
+
+ LIBC_INLINE static MemcmpReturnType block(CPtr p1, CPtr p2) {
+ if constexpr (Size == 1) {
+ return load_be_
diff <uint8_t>(p1, p2);
+ } else if constexpr (Size == 2) {
+ return load_be_
diff <uint16_t>(p1, p2);
+ } else if constexpr (Size == 4) {
+ return load_be_cmp<uint32_t>(p1, p2);
+ } else if constexpr (Size == 8) {
+ return load_be_cmp<uint64_t>(p1, p2);
+ } else if constexpr (details::useArrayType<Size, MaxSize>()) {
+ for (size_t offset = 0; offset < Size; offset += MaxSize)
+ if (Bcmp<MaxSize>::block(p1 + offset, p2 + offset))
+ return Memcmp<MaxSize>::block(p1 + offset, p2 + offset);
+ return MemcmpReturnType::ZERO();
+ } else if constexpr (Size == 3) {
+ if (auto value = Memcmp<2>::block(p1, p2))
+ return value;
+ return Memcmp<1>::block(p1 + 2, p2 + 2);
+ } else {
+ deferred_static_assert("Unimplemented Size");
+ }
+ }
+
+ LIBC_INLINE static MemcmpReturnType tail(CPtr p1, CPtr p2, size_t count) {
+ return block(p1 + count - SIZE, p2 + count - SIZE);
+ }
+
+ LIBC_INLINE static MemcmpReturnType head_tail(CPtr p1, CPtr p2,
+ size_t count) {
+ if (auto value = block(p1, p2))
+ return value;
+ return tail(p1, p2, count);
+ }
+
+ LIBC_INLINE static MemcmpReturnType loop_and_tail(CPtr p1, CPtr p2,
+ size_t count) {
+ static_assert(Size > 1, "a loop of size 1 does not need tail");
+ size_t offset = 0;
+ do {
+ if (auto value = block(p1 + offset, p2 + offset))
+ return value;
+ offset += SIZE;
+ } while (offset < count - SIZE);
+ return tail(p1, p2, count);
+ }
+};
+
} // namespace __llvm_libc::generic
#endif // LLVM_LIBC_SRC_STRING_MEMORY_UTILS_OP_GENERIC_H
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