From 72895656c7582d3d5007dac363d877f0bd1a0c67 Mon Sep 17 00:00:00 2001
From: NAKAMURA Takumi <geek4civic@gmail.com>
Date: Fri, 13 Jan 2017 01:13:10 +0000
Subject: [PATCH] Revert r291503, "Lift the 10-type limit for
 AlignedCharArrayUnion", and followings.

  r291503, "Lift the 10-type limit for AlignedCharArrayUnion"
  r291514, "Fix MSVC build of AlignedCharArrayUnion"
  r291515, "Revert the attempt to optimize the constexpr functions. MSVC does not handle this yet"
  r291519, "Try once again to fix the MSVC build of AlignedCharArrayUnion"

They has been failing on i686-linux.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@291875 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/Support/AlignOf.h    | 52 ++++++++++++++++++-------------
 unittests/Support/AlignOfTest.cpp | 18 -----------
 2 files changed, 30 insertions(+), 40 deletions(-)

diff --git a/include/llvm/Support/AlignOf.h b/include/llvm/Support/AlignOf.h
index 2d8297ee87d..abd19afa22f 100644
--- a/include/llvm/Support/AlignOf.h
+++ b/include/llvm/Support/AlignOf.h
@@ -102,37 +102,45 @@ LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(128)
 
 #endif // _MSC_VER
 
-// This code implements the equivalent of std::aligned_union from C++11.
-// That is supported by Visual Studio 2015 and GCC 5.1.
-// Once these are the baselines for LLVM, we can use std::aligned_union instead.
-
-namespace support {
 namespace detail {
-template <typename T1> constexpr size_t aligner() { return alignof(T1); }
+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 T1, typename T2, typename... Ts> constexpr size_t aligner() {
-  return (alignof(T1) > aligner<T2, Ts...>()) ? alignof(T1)
-                                              : aligner<T2, Ts...>();
-}
+  AlignerImpl() = delete;
+};
 
-template <typename T1> constexpr size_t sizer() { return sizeof(T1); }
-
-template <typename T1, typename T2, typename... Ts> constexpr size_t sizer() {
-  return (sizeof(T1) > sizer<T2, Ts...>()) ? sizeof(T1) : sizer<T2, Ts...>();
-}
+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)];
+};
 } // end namespace detail
-} // end namespace support
 
 /// \brief This union template exposes a suitably aligned and sized character
-/// array member which can hold elements of any of a number of types.
+/// array member which can hold elements of any of up to ten types.
 ///
 /// 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.
-template <typename... Ts>
-struct AlignedCharArrayUnion
-    : llvm::AlignedCharArray<support::detail::aligner<Ts...>(),
-                             support::detail::sizer<Ts...>()> {};
+/// 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>)> {
+};
 } // end namespace llvm
 
 #endif // LLVM_SUPPORT_ALIGNOF_H
diff --git a/unittests/Support/AlignOfTest.cpp b/unittests/Support/AlignOfTest.cpp
index dfcdc1484b3..388ca11b776 100644
--- a/unittests/Support/AlignOfTest.cpp
+++ b/unittests/Support/AlignOfTest.cpp
@@ -91,24 +91,6 @@ V8::~V8() {}
 
 template <typename M> struct T { M m; };
 
-typedef uint8_t t1;
-typedef uint16_t t2;
-typedef uint32_t t3;
-typedef uint64_t t4;
-typedef int8_t t5;
-typedef int16_t t6;
-typedef int32_t t7;
-typedef int64_t t8;
-typedef struct { uint8_t bytes[16]; } t9;
-typedef struct { uint16_t words[16]; } t10;
-typedef struct { uint32_t words[16]; } t11;
-typedef struct { uint64_t words[16]; } t12;
-
-typedef AlignedCharArrayUnion<t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12> U;
-
-static_assert(sizeof(U) == sizeof(uint64_t[16]), "Statically-computed size must be right");
-static_assert(alignof(U) == alignof(uint64_t), "Statically-computed alignment must be right");
-
 TEST(AlignOfTest, BasicAlignedArray) {
   EXPECT_LE(1u, alignof(AlignedCharArrayUnion<A1>));
   EXPECT_LE(2u, alignof(AlignedCharArrayUnion<A2>));