[PATCH] D129677: Disable machine function splitting for functions with inline asm br

[Adrian Tong via Phabricator via llvm-commits]

adriantong1024 added a comment.

In D129677#3653328 <https://reviews.llvm.org/D129677#3653328>, @efriedma wrote:

> AArch64 "b" has a range of +-128MB.  Which isn't enough for arbitrary programs.  So in general, you need a sequence like the following (assuming small code model):
>
>   adrp x0, dest
>   add x0, x0, :lo12:dest
>   blr x0
>
> That is, unless you're okay with the restriction that your binary is at most 128MB.  Which might be reasonable for the Linux kernel, I guess.  But again, something you'd want to document...
>
> ------
>
> That said, I'm surprised machine function splitting on aarch64 works without any other changes; currently, branch relaxation isn't aware of section markings at all.  Or do you have some other out-of-tree patches?

I think in case 128MB is not enough, the linker will help here. https://reviews.llvm.org/D39744

MFS does not work on AArch64, I am trying to make it work. I extended branch relaxation to handle cross-section branches. I plan to send out a RFC before sending up the out-of-tree patches I have.

Thanks !


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https://reviews.llvm.org/D129677