[PATCH v4 03/16] powerpc: Use a datatype for instructions

[Nicholas Piggin]

Jordan Niethe's on March 20, 2020 3:17 pm:
> Currently unsigned ints are used to represent instructions on powerpc.
> This has worked well as instructions have always been 4 byte words.
> However, a future ISA version will introduce some changes to
> instructions that mean this scheme will no longer work as well. This
> change is Prefixed Instructions. A prefixed instruction is made up of a
> word prefix followed by a word suffix to make an 8 byte double word
> instruction. No matter the endianess of the system the prefix always
> comes first. Prefixed instructions are only planned for powerpc64.
> 
> Introduce a ppc_inst type to represent both prefixed and word
> instructions on powerpc64 while keeping it possible to exclusively have
> word instructions on powerpc32, A latter patch will expand the type to
> include prefixed instructions but for now just typedef it to a u32.
> 
> Later patches will introduce helper functions and macros for
> manipulating the instructions so that powerpc64 and powerpc32 might
> maintain separate type definitions.

ppc_inst_t I would slightly prefer for a typedef like this.

Reviewed-by: Nicholas Piggin <npiggin at gmail.com>

> 
> Signed-off-by: Jordan Niethe <jniethe5 at gmail.com>