Re: RFC: Maintaining a per-macro invocation count

[Fangrui Song <i@maskray.me>]

On 2024-05-08, Nick Clifton wrote:
>Hi Guys,
>
>  The attached patch implements a extension to the assembler's macro
>  syntax, allowing a macro to access a count of the number of times that
>  it has been executed via the \+ pseudo-variable.  ie like this:
>
>    .macro foo
>      .print "I have been invoked \+ times"
>    .endm
>
>  This syntax is similar to the already supported \@ pseudo-variable,
>  except that the count is maintained on a per-macro basis.
>
>  The drive for this extension is that I want to be able to generate
>  N references to unique symbols in file A and then N definitions of
>  those symbols in file B.  Using assembler macros makes this easy,
>  providing that I can ensure that the names in file A will match those
>  in file B.  ie:
>
>  fileA.s:
>    .macro gen_refs count
>    .dc.a ref_\+
>    .if \count > 1
>    gen_refs \count-1
>    .endif
>    .endm
>
>    gen_refs 1000
>
>  fileB.s:
>    .macro gen_defs count
>    .global ref_\+
>    ref_\+ :
>    .if \count > 1
>    gen_defs \count-1
>    .endif
>    .endm
>
>    gen_defs 1000
>
>  (This is part of a larger exercise to generate some micro benchmarks
>  for the assembler that exercise various different features.  In this
>  case I am looking into relocation processing).

    (
    I am curious how intrusive it would be to support a new relocation
    format
    https://maskray.me/blog/2024-03-09-a-compact-relocation-format-for-elf#crel-relocation-format
    )

>  Comments, suggestions ?
>
>Cheers
>  Nick
>
>PS. In the course of creating this patch I noticed that the altmacto
>test (gas/testsuite/gas/macros/altmacro.d) does not appear to be run.
>So I have fixed that as well.
>


Thanks for the patch https://sourceware.org/cgit/binutils-gdb/commit/?id=83b972fc272db31ab48aa5cde84f47c98868d7c8
and the test fix!
This feature looks very useful, which resembles
https://gcc.gnu.org/onlinedocs/gcc/Extended-Asm.html#Special-format-strings

> ‘%=’
>
> Outputs a number that is unique to each instance of the asm statement in
> the entire compilation. This option is useful when creating local labels
> and referring to them multiple times in a single template that generates
> multiple assembler instructions.