[PATCH] D63707: [AArch64] Define ETE and TRBE system registers

[Oliver Stannard (Linaro) via Phabricator via llvm-commits]

ostannard added a comment.

> ETE shares most of the system registers with ETM and these were historically unconditionally enabled in LLVM.

I don't think this matters here - existing registers can stay as they are, and the new subtarget features should just cover new registers.

> It would be inconsistent to add a command line option, which enables just the few extra ETE registers

I don't see why this would be inconsistent, we now add subtarget features for every other new optional architectural feature. Maybe we should add a feature for ETM if it is optional, but that doesn't affect this patch.

> or it would break existing builds if we were to explicitly enable ETM registers.

Do you mean if we were to make ETM off by default? Agreed, we shouldn't do that.


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