[llvm] [IR] Add initial support for the byte type (PR #178666)

[Pedro Lobo via llvm-commits]

================
@@ -4432,6 +4432,40 @@ Examples:
 | ``i1942652``   | a really big integer of over 1 million bits.   |
 +----------------+------------------------------------------------+
 
+.. _t_byte:
+
+Byte Type
+""""""""""""
+
+:Overview:
+
+The byte type represents raw memory data in SSA registers. Each bit can be:
+
+* An integer bit (0 or 1)
+* Part of a pointer value
+* ``poison``
----------------
pedroclobo wrote:

`bytecast b32 %x to float` returns `poison` if any of the bits of `%x` is `poison` (and yes, it probably should have been answered in the RFC, although I noticed it is not totally clear there).

https://github.com/llvm/llvm-project/pull/178666