Re: [RFC,v2] x86_64: save_args out of line

From: H. Peter Anvin
Date: Tue Nov 18 2008 - 19:02:53 EST


Andi Kleen wrote:

Hmm, but if the assembler cannot auto generate it how should the assembler
writer know if he should use the macro or the direct instruction without
understanding CFI?

Also what will the assembler reader do? Do they first have to understand
CFI to understand everything? I personally would probably just
resort to objdump -S in this situation.

I think you're saying that for the user the macros would be just
equivalent, but if that's true they could be just auto generated by the assembler. But it's obviously not, so you'll end up
with the Linux magic asm dialect (and its maintenance disadvantages)
and you'll still require CFI knowledge to understand/write everything anyways.


We already have a "Linux magic asm dialect" which require CFI knowledge. Nothing can change that other than dumping the requirement that we have valid CFI data. However, the current code is hard to read and easy to trip up on. We can at least make it easier, especially to read -- and making it easier to read will help writers, too.

-hpa
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