jfb updated this revision to Diff 212252.
jfb added a comment.
Significantly simplify the patch.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D65249/new/
https://reviews.llvm.org/D65249
Files:
llvm/include/llvm/Support/AlignOf.h
llvm/unittests/Support/AlignOfTest.cpp
Index: llvm/unittests/Support/AlignOfTest.cpp
===================================================================
--- llvm/unittests/Support/AlignOfTest.cpp
+++ llvm/unittests/Support/AlignOfTest.cpp
@@ -233,16 +233,5 @@
#ifndef _MSC_VER
EXPECT_EQ(sizeof(V8), sizeof(AlignedCharArrayUnion<V8>));
#endif
-
- EXPECT_EQ(1u, (alignof(AlignedCharArray<1, 1>)));
- EXPECT_EQ(2u, (alignof(AlignedCharArray<2, 1>)));
- EXPECT_EQ(4u, (alignof(AlignedCharArray<4, 1>)));
- EXPECT_EQ(8u, (alignof(AlignedCharArray<8, 1>)));
- EXPECT_EQ(16u, (alignof(AlignedCharArray<16, 1>)));
-
- EXPECT_EQ(1u, sizeof(AlignedCharArray<1, 1>));
- EXPECT_EQ(7u, sizeof(AlignedCharArray<1, 7>));
- EXPECT_EQ(2u, sizeof(AlignedCharArray<2, 2>));
- EXPECT_EQ(16u, sizeof(AlignedCharArray<2, 16>));
}
} // end anonymous namespace
Index: llvm/include/llvm/Support/AlignOf.h
===================================================================
--- llvm/include/llvm/Support/AlignOf.h
+++ llvm/include/llvm/Support/AlignOf.h
@@ -6,7 +6,7 @@
//
//===----------------------------------------------------------------------===//
//
-// This file defines the AlignedCharArray and AlignedCharArrayUnion classes.
+// This file defines the AlignedCharArrayUnion class.
//
//===----------------------------------------------------------------------===//
@@ -18,128 +18,38 @@
namespace llvm {
-/// \struct AlignedCharArray
-/// Helper for building an aligned character array type.
-///
-/// This template is used to explicitly build up a collection of aligned
-/// character array types. We have to build these up using a macro and explicit
-/// specialization to cope with MSVC (at least till 2015) where only an
-/// integer literal can be used to specify an alignment constraint. Once built
-/// up here, we can then begin to indirect between these using normal C++
-/// template parameters.
-
-// MSVC requires special handling here.
-#ifndef _MSC_VER
-
-template<std::size_t Alignment, std::size_t Size>
-struct AlignedCharArray {
- alignas(Alignment) char buffer[Size];
-};
-
-#else // _MSC_VER
-
-/// Create a type with an aligned char buffer.
-template<std::size_t Alignment, std::size_t Size>
-struct AlignedCharArray;
-
-// We provide special variations of this template for the most common
-// alignments because __declspec(align(...)) doesn't actually work when it is
-// a member of a by-value function argument in MSVC, even if the alignment
-// request is something reasonably like 8-byte or 16-byte. Note that we can't
-// even include the declspec with the union that forces the alignment because
-// MSVC warns on the existence of the declspec despite the union member forcing
-// proper alignment.
-
-template<std::size_t Size>
-struct AlignedCharArray<1, Size> {
- union {
- char aligned;
- char buffer[Size];
- };
-};
-
-template<std::size_t Size>
-struct AlignedCharArray<2, Size> {
- union {
- short aligned;
- char buffer[Size];
- };
-};
-
-template<std::size_t Size>
-struct AlignedCharArray<4, Size> {
- union {
- int aligned;
- char buffer[Size];
- };
-};
+namespace detail {
-template<std::size_t Size>
-struct AlignedCharArray<8, Size> {
- union {
- double aligned;
- char buffer[Size];
- };
+template <typename T, typename... Ts> class AlignerImpl {
+ T t;
+ AlignerImpl<Ts...> rest;
+ AlignerImpl() = delete;
};
-
-// The rest of these are provided with a __declspec(align(...)) and we simply
-// can't pass them by-value as function arguments on MSVC.
-
-#define LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(x) \
- template<std::size_t Size> \
- struct AlignedCharArray<x, Size> { \
- __declspec(align(x)) char buffer[Size]; \
- };
-
-LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(16)
-LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(32)
-LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(64)
-LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(128)
-
-#undef LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT
-
-#endif // _MSC_VER
-
-namespace detail {
-template <typename T1,
- typename T2 = char, typename T3 = char, typename T4 = char,
- typename T5 = char, typename T6 = char, typename T7 = char,
- typename T8 = char, typename T9 = char, typename T10 = char>
-class AlignerImpl {
- T1 t1; T2 t2; T3 t3; T4 t4; T5 t5; T6 t6; T7 t7; T8 t8; T9 t9; T10 t10;
-
+template <typename T> class AlignerImpl<T> {
+ T t;
AlignerImpl() = delete;
};
-template <typename T1,
- typename T2 = char, typename T3 = char, typename T4 = char,
- typename T5 = char, typename T6 = char, typename T7 = char,
- typename T8 = char, typename T9 = char, typename T10 = char>
-union SizerImpl {
- char arr1[sizeof(T1)], arr2[sizeof(T2)], arr3[sizeof(T3)], arr4[sizeof(T4)],
- arr5[sizeof(T5)], arr6[sizeof(T6)], arr7[sizeof(T7)], arr8[sizeof(T8)],
- arr9[sizeof(T9)], arr10[sizeof(T10)];
+template <typename T, typename... Ts> union SizerImpl {
+ char arr[sizeof(T)];
+ SizerImpl<Ts...> rest;
};
+
+template <typename T> union SizerImpl<T> { char arr[sizeof(T)]; };
} // end namespace detail
-/// This union template exposes a suitably aligned and sized character
-/// array member which can hold elements of any of up to ten types.
+/// A suitably aligned and sized character array member which can hold elements
+/// of any type.
///
-/// These types may be arrays, structs, or any other types. The goal is to
-/// expose a char array buffer member which can be used as suitable storage for
-/// a placement new of any of these types. Support for more than ten types can
-/// be added at the cost of more boilerplate.
-template <typename T1,
- typename T2 = char, typename T3 = char, typename T4 = char,
- typename T5 = char, typename T6 = char, typename T7 = char,
- typename T8 = char, typename T9 = char, typename T10 = char>
-struct AlignedCharArrayUnion : llvm::AlignedCharArray<
- alignof(llvm::detail::AlignerImpl<T1, T2, T3, T4, T5,
- T6, T7, T8, T9, T10>),
- sizeof(::llvm::detail::SizerImpl<T1, T2, T3, T4, T5,
- T6, T7, T8, T9, T10>)> {
+/// These types may be arrays, structs, or any other types. This exposes a
+/// `buffer` member which can be used as suitable storage for a placement new of
+/// any of these types.
+template <typename T, typename... Ts> struct AlignedCharArrayUnion {
+ alignas(::llvm::detail::AlignerImpl<T, Ts...>) char buffer[sizeof(
+ llvm::detail::SizerImpl<T, Ts...>)];
};
+
} // end namespace llvm
#endif // LLVM_SUPPORT_ALIGNOF_H
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