[PATCH 2/2] z80-elf: support complex relocation symbols

[H. Peter Anvin]

On 2025-10-17 05:22, Jan Beulich wrote:
> On 13.10.2025 22:25, H. Peter Anvin wrote:
>> Some Z80 code, like the z88dk libc, does rely on being able to do
>> computation between external symbols.
>>
>> Enable complex relocation support (expression symbols) on Z80.
>>
>> [ Is there any fundamental reason not to do this globally? ]
> 
> Both for Z80 and for the more general question: Is the rest of the toolchain
> capable of dealing with that without any adjustments? Are other tools on the
> target (non-GNU linkers etc) capable of (correctly) consuming such objects?
> 
> Furthermore, looking at just symbol_relc_make_sym(), I can't help the
> impression that the symbol names produced there could conflict with (quoted)
> ordinary symbols. Such potential conflicts would be a reason to be careful
> with enabling of this functionality.
> 
> In any event such enabling would imo not only want but need to come with at
> least one testcase.
> 

So can we separate out Z80 -- a niche architecture for which I believe no
other ELF toolchain exists -- and the general case for a bit?

OBJ_COMPLEX_RELC is enabled on MEP (Toshiba Media Processor) and has been for
a long time. Are there no test cases there?

I didn't come up with the complex symbol format, but presumably, yes, they
could be created by hand if desired, although the likelihood of an actual
conflict seems very remote.

Note again that if that is a problem, *then it already exists*. The linker
*already* consumes expression symbols unconditionally on all architectures --
I have verified this.  The only effect of OBJ_COMPLEX_RELC is whether or not
gas can generate such symbols.

	-hpa