[PATCH] D61437: [AArch64] Static (de)allocation of SVE stack objects.

[Eli Friedman via Phabricator via llvm-commits]

efriedma added a comment.

> Does LLVM need this information to be available before register allocation so it knows whether to use the register or not?

You have to decide whether the register is reserved before register allocation, so the register allocator doesn't decide to use it, yes.  You should be able to change the answer after register allocation: basically, reserve the register through register allocation, then decide after register allocation you don't really need it and "unreserve" it.

I wouldn't really worry about optimizing this; dynamic stack allocation is rare in most C and C++ codebases, and one integer register likely doesn't matter much.

> Okay, so we should always use the FP if the function needs unwind table entries and has SVE spills/locals.

Yes.  Granted, you probably want a frame pointer anyway for functions with SVE spills/locals.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D61437/new/

https://reviews.llvm.org/D61437