[Lldb-commits] [PATCH] D159502: [lldb][AArch64] Add SME's Array Storage (ZA) register

Thu Sep 14 01:03:32 PDT 2023

DavidSpickett added inline comments.

================
Comment at: lldb/source/Plugins/Process/Linux/NativeRegisterContextLinux_arm64.cpp:597
+  // Here this means, does the system have ZA, not whether it is active.
+  if (GetRegisterInfo().IsZAEnabled()) {
+    error = ReadZAHeader();
----------------
omjavaid wrote:
> can you explain why in case of  ZA inactive shouldnt we fill the buffer with zeros here as well ?
Start state: ZA is disabled, reading ptrace gives you just the header.

What we must do to restore that state is to write the header back with no register data. So that's why we don't insert 0s here or trust the currently cached za buffer.

Unlike SVE, there's no flag to say make this active. The presence of the register data is that flag.

...which I will put in a comment as well.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D159502/new/

https://reviews.llvm.org/D159502