[Lldb-commits] [PATCH] D157846: [lldb][AArch64] Add SME's tests for SVE register state to TestArm64DynamicRegsets

[Muhammad Omair Javaid via Phabricator via lldb-commits]

omjavaid added a comment.

In D157846#4644241 <https://reviews.llvm.org/D157846#4644241>, @DavidSpickett wrote:

>> In this test can we figure out whether SVE was read from Streaming mode or normal SVE mode?? and if yes may be add a check for that.
>
> Not sure what you mean.
>
> If you mean:
>
> - write non-streaming SVE with one set of values
> - write streaming SVE with another
> - assert that lldb read the correct one
>
> There are a couple of issues there:
>
> - If lldb read the inactive mode, it would fail with unavailable register due to a failure down in lldb-sever. These tests would already catch that.
> - The kernel and the architecture say that the values of the registers for the mode you are coming from are wiped out on mode switch. So we wouldn't be able to truly read those values even if we were able to make the ptrace call and get some data.
>
> So it's covered, but does not/ can not be covered by checking values. It'll be correct values, or a complete failure to read.

Thanks for the detailed clarification.

I was actually curious if LLDB user can distinguish whether we are reading SVE registers from streaming mode or normal SVE mode. But yes only config registers like vg can tell that registers  are read in non-SVE(FPSIMD), normal SVE, or streaming modes.


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