[lldb] [Process/NetBSD] Fix reading FIP/FDP registers

[mgorny]

Summary

Fix reading FIP/FDP registers to correctly return segment and offset
parts. On amd64, this roughly matches the Linux behavior of splitting
the 64-bit FIP/FDP into two halves, and putting the higher 32 bits
into f*seg and lower into f*off. Well, actually we use only 16 bits
of higher half but the CPUs do not seem to handle more than that anyway.

[labath]

I'm assuming this is tested by D88583.

[mgorny]

Yes. We also need to fix our kernel but it's no less broken than it was before.

[krytarowski]

lldb/source/Plugins/Process/NetBSD/NativeRegisterContextNetBSD_x86_64.cpp

954

GetAsUInt32 above and GetAsUInt64 here?

[mgorny]

Fix mistype.

lldb/source/Plugins/Process/NetBSD/NativeRegisterContextNetBSD_x86_64.cpp

case lldb_fstat_x86_64:
     break;
   case lldb_ftag_x86_64:
     reg_value = (uint16_t)m_fpr.fxstate.fx_tw;
     break;
   case lldb_fop_x86_64:
     reg_value = (uint64_t)m_fpr.fxstate.fx_opcode;
     break;
   case lldb_fiseg_x86_64:
-    reg_value = (uint64_t)m_fpr.fxstate.fx_ip.fa_64;
+    reg_value = (uint32_t)m_fpr.fxstate.fx_ip.fa_32.fa_seg;
     break;
   case lldb_fioff_x86_64:
     reg_value = (uint32_t)m_fpr.fxstate.fx_ip.fa_32.fa_off;
     break;
   case lldb_foseg_x86_64:
-    reg_value = (uint64_t)m_fpr.fxstate.fx_dp.fa_64;
+    reg_value = (uint32_t)m_fpr.fxstate.fx_dp.fa_32.fa_seg;
     break;
   case lldb_fooff_x86_64:
     reg_value = (uint32_t)m_fpr.fxstate.fx_dp.fa_32.fa_off;
     break;
   case lldb_mxcsr_x86_64:
     reg_value = (uint32_t)m_fpr.fxstate.fx_mxcsr;
     break;
   case lldb_mxcsrmask_x86_64:
case lldb_fstat_x86_64:
     break;
   case lldb_ftag_x86_64:
     m_fpr.fxstate.fx_tw = reg_value.GetAsUInt16();
     break;
   case lldb_fop_x86_64:
     m_fpr.fxstate.fx_opcode = reg_value.GetAsUInt16();
     break;
   case lldb_fiseg_x86_64:
-    m_fpr.fxstate.fx_ip.fa_64 = reg_value.GetAsUInt64();
+    m_fpr.fxstate.fx_ip.fa_32.fa_seg = reg_value.GetAsUInt32();
     break;
   case lldb_fioff_x86_64:
     m_fpr.fxstate.fx_ip.fa_32.fa_off = reg_value.GetAsUInt32();
     break;
   case lldb_foseg_x86_64:
-    m_fpr.fxstate.fx_dp.fa_64 = reg_value.GetAsUInt64();
+    m_fpr.fxstate.fx_dp.fa_32.fa_seg = reg_value.GetAsUInt32();
     break;
   case lldb_fooff_x86_64:
     m_fpr.fxstate.fx_dp.fa_32.fa_off = reg_value.GetAsUInt32();
     break;
   case lldb_mxcsr_x86_64:
     m_fpr.fxstate.fx_mxcsr = reg_value.GetAsUInt32();
     break;
   case lldb_mxcsrmask_x86_64: