RFC: Annotate immediates in x86 disassembly

[Jan Beulich]

On 22.04.2026 11:02, Nick Clifton wrote:
> Hi Guys,
> 
>    Attached is a small potential patch that adds a new target specific
>    option to the x86 and x86_64 disassemblers: "-M annotate-immediates".
>    If enabled immediate operands which match a symbol's value will have
>    the name of that symbol displayed alongside them.
> 
>    For example, without the new option a line of disassembly might look
>    like this:
> 
>       400419:	bf 18 30 40 00       	mov    $0x403018,%edi
> 
>    whereas with the option enabled it could look like this:
> 
>       400419:	bf 18 30 40 00       	mov    $0x403018 [func1],%edi
> 
>    I find this helpful when looking at code that loads function
>    addresses into registers for example.
> 
>    What do you think ?  Would this be a useful addition to the assembler?

For the disassembler - yes, sure.

>    Notes:
>      * The feature is only enabled when disassembling executables as
>        the symbolic addresses in object files too often match small
>        ordinary constants.
> 
>      * The option parser will accept "-M annotate" or "-M
>        annotate-immediates" or "-M annotate<anything>".  I could make it
>        more strict, but I was not sure if it was worth it.

Will something equivalent then also work from the gdb prompt? (I expect
so, as I think per-arch option option parsing covers both, but I'd like
to double check.)

>    I did try to make this a generic option, rather than specific to the
>    x86/x86_64 architecture, but I quickly ran into problems with how
>    different ISAs handle the loading of constant values.  Still if this
>    kind of feature is considered useful it could be added to more
>    backends or a per-architecture basis.

Many architectures can only load range restricted constants in a single
insns, so there may not be that many where this is easily possible.

Jan