Hello!

Attached patch fixes PR19061, where gdb hangs/spins-on-cpu when
debugging any program on Alpha. The patch is effectively a forward
port of Richard's patch from the Comment #5 of the PR [1].


2017-12-15  Uros Bizjak  <ubizjak@gmail.com>
        Richard Henderson  <rth@redhat.com>

    PR gdb/19061
    * alpha-tdep.c (alpha_software_single_step): Call
    alpha_deal_with_atomic_sequence here.
    (set_gdbarch_software_single_step): Set to alpha_software_single_step.
    * nat/linux-ptrace.h [__alpha__]: Define GDB_ARCH_IS_TRAP_BRKPT
    and GDB_ARCH_IS_TRAP_HWBKPT.

Patch was tested on alphaev68-linux-gnu, also tested with gcc's
testsuite, where it fixed all hangs in guality.exp and
simulate-thread.exp testcases.

Please note that I have no commit access, so if approved, please
commit the patch to the source repository for me. I also have
functionally equivalent patch for gdb-8 branch which I plan to submit
later.

[1] https://sourceware.org/bugzilla/show_bug.cgi?id=19061#c5

Uros.