[PATCH] D157269: [Clang][AArch64] Diagnostics for SME attributes when target doesn't have 'sme'

[Aaron Ballman via Phabricator via cfe-commits]

aaron.ballman added a comment.

Clang bits generally LGTM aside from a minor request; I'll leave the final sign-off to an LLVM person so those changes can also be reviewed.



================
Comment at: clang/lib/Sema/SemaDecl.cpp:12092
+               diag::err_sme_definition_using_sm_in_non_sme_target);
+        if (UsesZA)
+          Diag(NewFD->getLocation(),
----------------
rsandifo-arm wrote:
> Suggest making this an `else if`.  We only need to give one error for a call to a streaming shared-ZA function, since the underlying error is the same.
Agreed; I think we need only one diagnostic in that case.


================
Comment at: clang/test/Sema/aarch64-sme-func-attrs-without-target-feature.cpp:20
+
+// No code is generated for declarations, so it should be fine to declare using the attribute.
+void streaming_compatible_decl() __arm_streaming_compatible; // OK
----------------
rsandifo-arm wrote:
> aaron.ballman wrote:
> > Is this a requirement of the specification? I guess I was surprised we're going to these lengths rather than diagnosing the attribute in SemaDeclAttr.cpp when sme is not enabled.
> Yeah.  The problem is that it's possible (and reasonable!) to enable SME for only part of a translation unit.  E.g. an ifunc might have SME and non-SME implementations, with those implementations being in the same translation unit.  Things like the `target` and `target_version` attributes exist to allow this.
> 
> A function that's compiled with SME enabled might want to call streaming functions.  There therefore needs to be a way of declaring streaming functions without assuming that the whole TU is SME.
Ah, thank you for the explanation, then this extra effort makes a lot more sense.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D157269/new/

https://reviews.llvm.org/D157269