[Bug debug/104169] New: GDB unable to set $xmm2-7 register but able to set $xmm0-1 on non-AVX machines

[contact at lsferreira dot net]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104169

            Bug ID: 104169
           Summary: GDB unable to set $xmm2-7 register but able to set
                    $xmm0-1 on non-AVX machines
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: debug
          Assignee: unassigned at gcc dot gnu.org
          Reporter: contact at lsferreira dot net
  Target Milestone: ---

When running on my "Intel(R) Xeon(R) CPU E7-4860", I can't set xmm2 to xmm7
registers on GDB. On a more recent CPU "Intel(R) Core(TM) m3-7Y30" this seems
to set just fine. I also tested this on a libvirt clean environment with an
Intel Core 2 Duo and Intel Ivy Bridge family CPU (emulated settings), and the
one without AVX did fail to set.

To reproduce the issue, you can run any process on a non-AVX machine:

$ gdb /usr/bin/bash
> r -c 'kill -SIGILL $$'
> p $xmm7.uint128
> set $xmm7.uint128 = 35322350018591
> p $xmm7.uint128

If you try with $xmm0 or $xmm1 it works just fine.