Is it possible to specify a hexadecimal number in LLVM IR code?

Question

For example:

error: floating point constant invalid for type
      %3 = and i8 0x80, %2
                  ^

Answer 1

From a scan of the IR reference manual, it looks like hexadecimal literals are reserved for the representation of floating point numbers that cannot be exactly represented in a reasonable number of digits.

Which explains why your error message says that the floating point constant is invalid.