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SubjectRe: [RFC,v2] x86_64: save_args out of line
Andi Kleen wrote:
>> I don't think auto-generation is very a useful angle to take for this any
>> time soon. Explicit (but simple) macros in the assembly is what I favor.
>>
>
> Do you mean macros that generate both the instruction and the CFI
> or separate? The major disadvantage of doing it together in a
> single macro is that it is not really readable for any assembler
> programmer anymore, but starts becoming a Linux specific assembler
> language. Likely not a good thing for maintenance. anyone who
> wants to know the real assembler would need to read objdump -S
> output, which is not nice.
>
> Perhaps it would be a reasonable readability improvement to just use shorter
> cfi macros which are not shouted?

Not really. At the moment we have two parallel assembly languages which
say different things about the same instructions. In practice, almost
nobody understands the cfi parts, so they just get ignored while the x86
instructions change around them, leaving them either stale or missing.

If we had a sensible macro layer which emits both instructions and cfi
annotations, it at least means that people who write plain x86
instructions will simply get no annotations, and people who bother to
learn the (clearly and fully documented) macros will get the best of both.

J


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