From 15ed558a29d8f6e2e2ccaf76eeffb9d148161c6b Mon Sep 17 00:00:00 2001
From: Glen Fernandes <glenfe@live.com>
Date: Sun, 5 Mar 2017 21:39:22 -0500
Subject: [PATCH] Further simplify alignment logic in allocate

---
 .../boost/smart_ptr/allocate_shared_array.hpp | 48 +++++++++----------
 1 file changed, 22 insertions(+), 26 deletions(-)

diff --git a/include/boost/smart_ptr/allocate_shared_array.hpp b/include/boost/smart_ptr/allocate_shared_array.hpp
index 1366aee..2028795 100644
--- a/include/boost/smart_ptr/allocate_shared_array.hpp
+++ b/include/boost/smart_ptr/allocate_shared_array.hpp
@@ -350,40 +350,36 @@ sp_array_default(T* storage, std::size_t size)
 }
 #endif
 
-template<class T, class U>
+template<class T, std::size_t N>
 struct sp_less_align {
     enum {
-        value = (boost::alignment_of<T>::value) <
-            (boost::alignment_of<U>::value)
+        value = (boost::alignment_of<T>::value) < N
     };
 };
 
-template<class T, class U>
+template<class T, std::size_t N>
 BOOST_CONSTEXPR inline
-typename sp_enable<sp_less_align<T, U>::value &&
-    (sizeof(U) % 2 == 0), std::size_t>::type
-sp_align(std::size_t size) BOOST_NOEXCEPT_OR_NOTHROW
+typename sp_enable<sp_less_align<T, N>::value, std::size_t>::type
+sp_align(std::size_t size) BOOST_NOEXCEPT
 {
-    return (sizeof(T) * size + sizeof(U) - 1) & ~(sizeof(U) - 1);
+    return (sizeof(T) * size + N - 1) & ~(N - 1);
 }
 
-template<class T, class U>
+template<class T, std::size_t N>
 BOOST_CONSTEXPR inline
-typename sp_enable<sp_less_align<T, U>::value &&
-    (sizeof(U) % 2 != 0), std::size_t>::type
-sp_align(std::size_t size) BOOST_NOEXCEPT_OR_NOTHROW
-{
-    return (sizeof(T) * size + sizeof(U) - 1) / sizeof(U) * sizeof(U);
-}
-
-template<class T, class U>
-BOOST_CONSTEXPR inline
-typename sp_enable<!sp_less_align<T, U>::value, std::size_t>::type
+typename sp_enable<!sp_less_align<T, N>::value, std::size_t>::type
 sp_align(std::size_t size) BOOST_NOEXCEPT
 {
     return sizeof(T) * size;
 }
 
+template<class T>
+BOOST_CONSTEXPR inline std::size_t
+sp_types(std::size_t size) BOOST_NOEXCEPT
+{
+    return (size + sizeof(T) - 1) / sizeof(T);
+}
+
 template<class T, std::size_t N>
 class sp_size_array_deleter {
 public:
@@ -670,19 +666,19 @@ public:
 
     value_type* allocate(std::size_t count) {
         type_allocator allocator(allocator_);
-        std::size_t head = sp_align<value_type, type>(count);
-        std::size_t tail = sp_align<T, type>(size_);
-        std::size_t size = (head + tail) / sizeof(type);
+        std::size_t head = sp_align<value_type, alignment>(count);
+        std::size_t tail = sizeof(T) * size_;
+        std::size_t size = sp_types<type>(head + tail);
         type* address = allocator.allocate(size);
-        *result_ = address + head / sizeof(type);
+        *result_ = reinterpret_cast<char*>(address) + head;
         return reinterpret_cast<value_type*>(address);
     }
 
     void deallocate(value_type* value, std::size_t count) {
         type_allocator allocator(allocator_);
-        std::size_t head = sp_align<value_type, type>(count);
-        std::size_t tail = sp_align<T, type>(size_);
-        std::size_t size = (head + tail) / sizeof(type);
+        std::size_t head = sp_align<value_type, alignment>(count);
+        std::size_t tail = sizeof(T) * size_;
+        std::size_t size = sp_types<type>(head + tail);
         allocator.deallocate(reinterpret_cast<type*>(value), size);
     }