[PATCH] [Support] Add BitHacks.h - generic bit utility functions.

[Alex Rosenberg]

================
Comment at: include/llvm/Support/BitHacks.h:195
@@ +194,3 @@
+template <typename T>
+T reverseBits(T Val) {
+  unsigned char in[sizeof(Val)];
----------------
Some architectures, e.g. ARM, have instructions for this as this operation is typically part of an FFT.


http://llvm-reviews.chandlerc.com/D841