[PATCH] D110258: [AArch64] Always add -tune-cpu argument to -cc1 driver

Mon Sep 27 02:35:16 PDT 2021

david-arm added a comment.

In D110258#3023818 <https://reviews.llvm.org/D110258#3023818>, @dmgreen wrote:

> Sounds great.  Glad to see us taking this route.
>
> Unfortunately I think we do need to split the subtargetfeatures up into arch flags and tune flags. Same for the details in AArch64Subtarget::initializeProperties. It is hopefully a fairly mechanical process, but they are an important part of tuning and without them -mtune is only a half-working option.
>
> Are you happy to give that a go too?

Hi @dmgreen, sure I can try. The only problem is that I don't really understand what to do here. I used the X86Subtarget as a guidance and the TuneCPU flag only seems to be used for scheduling and nothing else. It's not obvious to me how the TuneCPU flag decides the features as I thought it was purely for scheduling?

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https://reviews.llvm.org/D110258