[PATCH] D107902: [AArch64][SME] Disable NEON on generic CPU for streaming mode

[Cullen Rhodes via Phabricator via llvm-commits]

c-rhodes marked an inline comment as done.
c-rhodes added inline comments.


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Comment at: llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCTargetDesc.cpp:60
 
-  return createAArch64MCSubtargetInfoImpl(TT, CPU, /*TuneCPU*/ CPU, FS);
+  // Most of the NEON instruction set isn't supported in streaming mode on SME
+  // targets, but if no CPU is specified the default is "generic", which
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paulwalker-arm wrote:
> Does this need to be dependent on `CPU="Generic"`? I'm thinking you may still need to disable NEON even when targeting a known cpu.
> 
> I guess I expected some explicit opting in to the fact NEON will be disabled.  That's to say I figured the user would explicitly ask for `+streaming-sve` and by not also explicitly asking for `+neon` then they are making a conscious choice to disable NEON.
> Does this need to be dependent on `CPU="Generic"`? I'm thinking you may still need to disable NEON even when targeting a known cpu.

CPUs with SME support will be defined without `FeatureNEON` in the features, so this won't be an issue?

> I guess I expected some explicit opting in to the fact NEON will be disabled.  That's to say I figured the user would explicitly ask for `+streaming-sve` and by not also explicitly asking for `+neon` then they are making a conscious choice to disable NEON.

That's what this change implements?


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D107902/new/

https://reviews.llvm.org/D107902