Reproduction micros

On Jul 21, 2016, at 4:22 PM, Peter Corlett <abuse at cabal.org.uk> wrote: ... A predicated instruction is one that does or does not execute based on some condition. CISC machines generally use condition codes (aka flags), and only have predicated branch instructions. Branch-not-equal, that kind of things. In ARM, *all* instructions can be predicated. Because instructions are 32 bits wide, it has the luxury of allocating four bits to select from one of 16 possible predicates based on the CPU flags. One predicate is "always" so one can also unconditionally execute instructions. An occasionally forgotten feature is that ALU operations also have a S-bit to indicate whether they should update the flags based on the result, or leave them alone.