[lldb][AArch64] Do not crash if NT_ARM_TLS is missing

[D156118](https://reviews.llvm.org/D156118) states that this note is
always present, but it is better to check it explicitly, as otherwise
`lldb` may crash when trying to read registers.

lldb/source/Plugins/Process/Utility/RegisterInfoPOSIX_arm64.cpp

@@ -254,9 +254,10 @@ RegisterInfoPOSIX_arm64::RegisterInfoPOSIX_arm64(
       if (m_opt_regsets.AllSet(eRegsetMaskMTE))
         AddRegSetMTE();
 
-      // The TLS set always contains tpidr but only has tpidr2 when SME is
-      // present.
-      AddRegSetTLS(m_opt_regsets.AllSet(eRegsetMaskSSVE));
+      if (m_opt_regsets.AllSet(eRegsetMaskTLS))
+        // The TLS set always contains tpidr but only has tpidr2 when SME is
+        // present.
+        AddRegSetTLS(m_opt_regsets.AllSet(eRegsetMaskSSVE));
 
       if (m_opt_regsets.AnySet(eRegsetMaskSSVE))
         AddRegSetSME(m_opt_regsets.AnySet(eRegsetMaskZT));

lldb/test/Shell/Process/elf-core/aarch64-no-NT_ARM_TLS.yaml

@@ -0,0 +1,34 @@
+# REQUIRES: aarch64
+
+## Check that lldb does not crash if a core file does not contain an NT_ARM_TLS
+## note while there are notes for other dynamic register sets.
+
+# RUN: yaml2obj %s -o %t
+# RUN: %lldb -c %t -o "re r -a" | FileCheck %s
+
+# CHECK:      Pointer Authentication Registers:
+# CHECK-NEXT:   data_mask =
+# CHECK-NEXT:   code_mask =
+# CHECK-NOT:  Thread Local Storage Registers:
+
+--- !ELF
+FileHeader:
+  Class:        ELFCLASS64
+  Data:         ELFDATA2LSB
+  Type:         ET_CORE
+  Machine:      EM_AARCH64
+ProgramHeaders:
+  - Type:       PT_NOTE
+    FirstSec:   .note
+    LastSec:    .note
+Sections:
+  - Name:       .note
+    Type:       SHT_NOTE
+    Notes:
+      - Name:   CORE
+        Desc:   0b00000000000000000000000b00000000000000000000000000000000000000389300001b930000389300001b930000000000000000000000000000000000000000000000000000e02e0000000000000000000000000000119100000000000000000000000000005ee100000000000000000000000000002f00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000400162e2ffff00005801400000000000200162e2ffff0000240140000000000000000000000000000100000000000000
+        Type:   NT_PRSTATUS
+      - Name:   LINUX
+        Desc:   0000000000007f000000000000007f00
+        Type:   NT_ARM_PAC_MASK
+...

lldb/test/Shell/Process/elf-core/lit.local.cfg

@@ -0,0 +1 @@
+config.suffixes = ['.yaml']