From 08b79b9bbfa96ee6dcbc4d58bf082c9e6df911df Mon Sep 17 00:00:00 2001
From: Chris Robinson <chris.kcat@gmail.com>
Date: Thu, 20 Dec 2018 11:46:40 -0800
Subject: Add an assume_aligned helper

---
 common/almalloc.h | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/common/almalloc.h b/common/almalloc.h
index d9b285fe..7ec07004 100644
--- a/common/almalloc.h
+++ b/common/almalloc.h
@@ -68,6 +68,21 @@ struct allocator : public std::allocator<T> {
     { }
 };
 
+template<size_t alignment, typename T>
+inline T* assume_aligned(T *ptr) noexcept
+{
+    static_assert((alignment & (alignment-1)) == 0, "alignment must be a power of 2");
+#ifdef __GNUC__
+    return reinterpret_cast<T*>(__builtin_assume_aligned(ptr, alignment));
+#elif defined(_MSC_VER)
+    auto ptrval = reinterpret_cast<uintptr_t>(ptr);
+    if((ptrval&(alignment-1)) != 0) __assume(0);
+    return reinterpret_cast<T*>(ptrval);
+#else
+    return ptr;
+#endif
+}
+
 } // namespace al
 
 #endif /* AL_MALLOC_H */
-- 
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