[Bug gdb/29471] gdb 12.1 'i r' command doesn't recognise register NZCV under target aarch64-none-elf

["luis.machado at arm dot com" <sourceware-bugzilla@sourceware.org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=29471

--- Comment #3 from Luis Machado <luis.machado at arm dot com> ---
Hi Pete,

I don't think there is anything wrong with QEMU or GDB. You can find all the
bits you described in the CPSR.

The CPSR is described like so:

  <flags id="cpsr_flags" size="4">
    <!-- Stack Pointer.  -->
    <field name="SP" start="0" end="0"/>

    <!-- Exception Level.  -->
    <field name="EL" start="2" end="3"/>
    <!-- Execution state.  -->
    <field name="nRW" start="4" end="4"/>

    <!-- FIQ interrupt mask.  -->
    <field name="F" start="6" end="6"/>
    <!-- IRQ interrupt mask.  -->
    <field name="I" start="7" end="7"/>
    <!-- SError interrupt mask.  -->
    <field name="A" start="8" end="8"/>
    <!-- Debug exception mask.  -->
    <field name="D" start="9" end="9"/>

    <!-- ARMv8.5-A: Branch Target Identification BTYPE.  -->
    <field name="BTYPE" start="10" end="11"/>

    <!-- ARMv8.0-A: Speculative Store Bypass.  -->
    <field name="SSBS" start="12" end="12"/>

    <!-- Illegal Execution state.  -->
    <field name="IL" start="20" end="20"/>
    <!-- Software Step.  -->
    <field name="SS" start="21" end="21"/>
    <!-- ARMv8.1-A: Privileged Access Never.  -->
    <field name="PAN" start="22" end="22"/>
    <!-- ARMv8.2-A: User Access Override.  -->
    <field name="UAO" start="23" end="23"/>
    <!-- ARMv8.4-A: Data Independent Timing.  -->
    <field name="DIT" start="24" end="24"/>
    <!-- ARMv8.5-A: Tag Check Override.  -->
    <field name="TCO" start="25" end="25"/>

    <!-- Overflow Condition flag.  -->
    <field name="V" start="28" end="28"/>
    <!-- Carry Condition flag.  -->
    <field name="C" start="29" end="29"/>
    <!-- Zero Condition flag.  -->
    <field name="Z" start="30" end="30"/>
    <!-- Negative Condition flag.  -->
    <field name="N" start="31" end="31"/>
  </flags>
  <reg name="cpsr" bitsize="32" type="cpsr_flags"/>

For the 1-bit fields, GDB will show the field name if the bit is 1. Otherwise
nothing will be shown.

So in your example...

---
cpsr           0x200003cd          [ SP EL=3 F I A D BTYPE=0 C ]
---

You can see the various bits that are set. For fields with more than a single
bit, you will see the value, like BTYPE.

Does that clarify things?

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