[ARM] Add Cortex-X1C Support for Clang and LLVM

[stuij]

Summary

This patch upstreams support for the Arm-v8 Cortex-X1C processor for AArch64 and
ARM.

For more information, see:

• https://community.arm.com/arm-community-blogs/b/announcements/posts/arm-cortex-x1c
• https://developer.arm.com/documentation/101968/0002/Functional-description/Technical-overview/Components

The following people contributed to this patch:

• Simon Tatham
• Ties Stuij

[dmgreen]

llvm/include/llvm/Support/AArch64TargetParser.def

205

Should this have the same features as the cortex-x1? AEK_DOTPROD and AEK_FP16 and the rest?

llvm/lib/Target/AArch64/AArch64.td

719

This can be the same as TuneX1. It might be worth using the same TuneX1 in both the cortex-x1 and cortex-x1c.

978

Should this have dotprod and RCPC?

The TRM isn't super clear on what features are present. Is FP16FML present?

[stuij]

llvm/include/llvm/Support/AArch64TargetParser.def

205

Yes, you're right. I've added these.

llvm/lib/Target/AArch64/AArch64.td

978

Right, the addition of FP16FML must have been copied from the X1, which was later removed when upstreaming. I removed it here, and I added dotard and RCPC. The only relevant change from X1 to X1C is the addition of PAUTH, as per the TRM.

[stuij]

addressed review comments

[dmgreen]

Thanks for the update. Same(ish) questions for the Arm side. Otherwise this LGTM

llvm/include/llvm/Support/ARMTargetParser.def

332

Should this match the ARM::AEK_FP16 | ARM::AEK_DOTPROD from cortex-x1 too?

llvm/lib/Target/ARM/ARM.td

1446

Should this have ProcX1C added?

[dmgreen]

Oh, also is there an ID for this CPU that is worth adding to getHostCPUNameForARM in Host.cpp?

[stuij]

Thanks for the update. Same(ish) questions for the Arm side. Otherwise this LGTM

Ai, thanks. Should have checked Arm as well.

Oh, also is there an ID for this CPU that is worth adding to getHostCPUNameForARM in Host.cpp?

Yup, thanks. Added.

llvm/lib/Target/ARM/ARM.td

1446

yes :)

[stuij]

addressed review comments

[dmgreen]

Thanks. LGTM