Re: [llvm/llvm-project] A few default FEAT_??? mismatches for cortex-a78a and cortex-x1c (that should be the same for both) (Issue #62383)

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From: Jonathan Thackray <notifications@github.com>
Subject: Re: [llvm/llvm-project] A few default FEAT_??? mismatches for cortex-a78a and cortex-x1c (that should be the same for both) (Issue #62383)
Date: January 4, 2024 at 12:07:00 PST
To: llvm/llvm-project <llvm-project@noreply.github.com>
Cc: Mark Millard <marklmi26-fbsd@yahoo.com>, Author <author@noreply.github.com>
Reply-To: llvm/llvm-project <reply+ABC3N4NRZFDXXOGMWBEJM56DURBGJEVBNHHGI3NILQ@reply.github.com>


Closed #62383 as completed via #76932.
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That was after .  . .
Begin forwarded message:

From: Jonathan Thackray <notifications@github.com>
Subject: Re: [llvm/llvm-project] A few default FEAT_??? mismatches for cortex-a78a and cortex-x1c (that should be the same for both) (Issue #62383)
Date: January 3, 2024 at 09:28:57 PST
To: llvm/llvm-project <llvm-project@noreply.github.com>
Cc: Mark Millard <marklmi26-fbsd@yahoo.com>, Author <author@noreply.github.com>
Reply-To: llvm/llvm-project <reply+ABC3N4PTDTMFVZGVJH35ZVODULF5TEVBNHHGI3NILQ@reply.github.com>


Thanks for spotting this.
I also checked some other Technical Reference Manuals, and it would appear that the Arm Cortex-X2 also supports Flag Manipulation, for bits 52-55 (TS) of ID_AA64ISAR0_EL1. I will add AArch64::AEK_FLAGM to both the Arm Cortex-X1C and Arm Cortex-X2 defined in llvm/include/llvm/TargetParser/AArch64TargetParser.h. The Arm Cortex-X1 does not support FLAGM.
It appears that there is nothing to do in this bugfix for FEAT_LRCPC2 and FEAT_LSE2 as they are not currently fully defined.
I will also remove AArch64::AEK_FP16FML from the Arm Cortex-A78C, as the Technical Reference Manual indicates this is not supported.
TRM links:
Arm Cortex-A78C: https://developer.arm.com/documentation/101430/latest/
Arm Cortex-X1: https://developer.arm.com/documentation/101433/latest/
Arm Cortex-X1C: https://developer.arm.com/documentation/101968/latest/
Arm Cortex-X2: https://developer.arm.com/documentation/101803/latest/
Arm Cortex-X3: https://developer.arm.com/documentation/101602/latest/
Arm Cortex-X4: https://developer.arm.com/documentation/102484/latest/
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Mark Millard
marklmi at yahoo.com