Proper data alignment for allocator and lazy constructor

libuavcan/include/uavcan/dynamic_memory.hpp

@@ -117,7 +117,13 @@ class PoolAllocator : public IPoolAllocator, Noncopyable
     };
 
     Node* free_list_;
-    uint8_t pool_[PoolSize] __attribute__((aligned(16)));  // TODO: compiler-independent alignment
+    union
+    {
+         uint8_t bytes[PoolSize];
+         long double _aligner1;
+         long long _aligner2;
+         Node _aligner3;
+    } pool_;
 
     // Noncopyable
     PoolAllocator(const PoolAllocator&);
@@ -127,9 +133,9 @@ public:
     static const int NumBlocks = int(PoolSize / BlockSize);
 
     PoolAllocator()
-        : free_list_(reinterpret_cast<Node*>(pool_)) // TODO: alignment
+        : free_list_(reinterpret_cast<Node*>(pool_.bytes))
     {
-        memset(pool_, 0, PoolSize);
+        memset(pool_.bytes, 0, PoolSize);
         for (int i = 0; i < NumBlocks - 1; i++)
         {
             free_list_[i].next = free_list_ + i + 1;
@@ -165,8 +171,8 @@ public:
     bool isInPool(const void* ptr) const
     {
         return
-            ptr >= pool_ &&
+            ptr >= pool_.bytes &&
-            ptr < (pool_ + PoolSize);
+            ptr < (pool_.bytes + PoolSize);
     }
 
     std::size_t getBlockSize() const { return BlockSize; }

libuavcan/include/uavcan/util/lazy_constructor.hpp

@@ -18,7 +18,13 @@ namespace uavcan
 template <typename T>
 class LazyConstructor
 {
-    unsigned char data_[sizeof(T)] __attribute__((aligned(16)));  // TODO: compiler-independent alignment
+    union
+    {
+        unsigned char pool[sizeof(T)];
+        long double _aligner1;
+        long long _aligner2;
+    } data_;
+
     T* ptr_;
 
     void ensureConstructed() const
@@ -47,13 +53,13 @@ public:
     LazyConstructor()
         : ptr_(NULL)
     {
-        std::fill(data_, data_ + sizeof(T), 0);
+        std::fill(data_.pool, data_.pool + sizeof(T), 0);
     }
 
     LazyConstructor(const LazyConstructor<T>& rhs)
         : ptr_(NULL)
     {
-        std::fill(data_, data_ + sizeof(T), 0);
+        std::fill(data_.pool, data_.pool + sizeof(T), 0);
         if (rhs)
         {
             construct<const T&>(*rhs);  // Invoke copy constructor
@@ -89,13 +95,13 @@ public:
             ptr_->~T();
         }
         ptr_ = NULL;
-        std::fill(data_, data_ + sizeof(T), 0);
+        std::fill(data_.pool, data_.pool + sizeof(T), 0);
     }
 
     void construct()
     {
         ensureNotConstructed();
-        ptr_ = new (static_cast<void*>(data_)) T();
+        ptr_ = new (static_cast<void*>(data_.pool)) T();
     }
 
 // MAX_ARGS = 6
@@ -104,7 +110,7 @@ public:
 //     void construct(%s)
 //     {
 //         ensureNotConstructed();
-//         ptr_ = new (static_cast<void*>(data_)) T(%s);
+//         ptr_ = new (static_cast<void*>(data_.pool)) T(%s);
 //     }'''
 // for nargs in range(1, MAX_ARGS + 1):
 //     nums = [(x + 1) for x in range(nargs)]
@@ -117,21 +123,21 @@ public:
     void construct(typename ParamType<P1>::Type p1)
     {
         ensureNotConstructed();
-        ptr_ = new (static_cast<void*>(data_)) T(p1);
+        ptr_ = new (static_cast<void*>(data_.pool)) T(p1);
     }
 
     template <typename P1, typename P2>
     void construct(typename ParamType<P1>::Type p1, typename ParamType<P2>::Type p2)
     {
         ensureNotConstructed();
-        ptr_ = new (static_cast<void*>(data_)) T(p1, p2);
+        ptr_ = new (static_cast<void*>(data_.pool)) T(p1, p2);
     }
 
     template <typename P1, typename P2, typename P3>
     void construct(typename ParamType<P1>::Type p1, typename ParamType<P2>::Type p2, typename ParamType<P3>::Type p3)
     {
         ensureNotConstructed();
-        ptr_ = new (static_cast<void*>(data_)) T(p1, p2, p3);
+        ptr_ = new (static_cast<void*>(data_.pool)) T(p1, p2, p3);
     }
 
     template <typename P1, typename P2, typename P3, typename P4>
@@ -139,7 +145,7 @@ public:
                    typename ParamType<P4>::Type p4)
     {
         ensureNotConstructed();
-        ptr_ = new (static_cast<void*>(data_)) T(p1, p2, p3, p4);
+        ptr_ = new (static_cast<void*>(data_.pool)) T(p1, p2, p3, p4);
     }
 
     template <typename P1, typename P2, typename P3, typename P4, typename P5>
@@ -147,7 +153,7 @@ public:
                    typename ParamType<P4>::Type p4, typename ParamType<P5>::Type p5)
     {
         ensureNotConstructed();
-        ptr_ = new (static_cast<void*>(data_)) T(p1, p2, p3, p4, p5);
+        ptr_ = new (static_cast<void*>(data_.pool)) T(p1, p2, p3, p4, p5);
     }
 
     template <typename P1, typename P2, typename P3, typename P4, typename P5, typename P6>
@@ -155,7 +161,7 @@ public:
                    typename ParamType<P4>::Type p4, typename ParamType<P5>::Type p5, typename ParamType<P6>::Type p6)
     {
         ensureNotConstructed();
-        ptr_ = new (static_cast<void*>(data_)) T(p1, p2, p3, p4, p5, p6);
+        ptr_ = new (static_cast<void*>(data_.pool)) T(p1, p2, p3, p4, p5, p6);
     }
 };