[PATCH] Use returns_nonnull in BumpPtrAllocator and MallocAllocator to avoid null-check in placement new

[Chandler Carruth]

Regardless of whether we can add more portable tricks, this seems like a strict improvement in the allocation API. Awesome speedups too!

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Comment at: include/llvm/Support/Allocator.h:93
@@ -92,2 +92,3 @@
 
-  void *Allocate(size_t Size, size_t /*Alignment*/) { return malloc(Size); }
+  void LLVM_ATTRIBUTE_RETURNS_NONNULL *Allocate(size_t Size,
+                                                size_t /*Alignment*/) {
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Why is this attribute in a different location?

http://reviews.llvm.org/D4989