[PATCH] D127798: [AArch64] Define __ARM_FEATURE_RCPC

Wed Jun 15 10:49:52 PDT 2022

mingmingl added a comment.

In D127798#3585025 <https://reviews.llvm.org/D127798#3585025>, @tyb0807 wrote:

> The patch looks correct to me, but looking at https://github.com/ARM-software/acle/blob/main/main/acle.md where all the ACLE macros are defined, I'm not sure that `__ARM_FEATURE_RCPC` is there currently. Maybe you also want to submit a patch there, or at least explain the context of this change please?

thanks for taking a look!

Before this patch, there is a piece of inline assembly like [1] that uses `LDAPR` and guarded by `#if defined(__aarch64__)`. Since not all aarch64 platforms support `LDAPR`, we want to further guard the usage of `LDAPR` by MACRO `__ARM_FEATURE_RCPC`. May I know if there are alternatives for this use case, if introducing `__ARM_FEATURE_RCPC` sounds ad-hoc?

I'm glad to send a patch to add  `__ARM_FEATURE_RCPC` to https://github.com/ARM-software/acle/blob/main/main/acle.md if it's conventional to do so. Just let me know your suggestions!

[1]

  add x6, x1, x4
  ldapr x5, [x6]

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D127798/new/

https://reviews.llvm.org/D127798