[1/3] Redesign mock environment for gdbarch selftests

  A following patch will remove this a hack from within regcache's
implementation:

  struct regcache *
  get_thread_arch_regcache (ptid_t ptid, struct gdbarch *gdbarch)
  {
    struct address_space *aspace;

    /* For the benefit of "maint print registers" & co when debugging an
       executable, allow dumping the regcache even when there is no
       thread selected (target_thread_address_space internal-errors if
       no address space is found).  Note that normal user commands will
       fail higher up on the call stack due to no
       target_has_registers.  */
    aspace = (ptid_equal (null_ptid, ptid)
	      ? NULL
	      : target_thread_address_space (ptid));

i.e., it'll no longer be possible to try to build a regcache for
null_ptid.  That change alone would regress the gdbarch self tests
though, causing this:

  (gdb) maintenance selftest
  [...]
  Running selftest register_to_value.
  src/gdb/inferior.c:309: internal-error: inferior* find_inferior_pid(int): Assertion `pid != 0' failed.
  A problem internal to GDB has been detected,
  further debugging may prove unreliable.
  Quit this debugging session? (y or n) FAIL: gdb.gdb/unittest.exp: maintenance selftest (GDB internal error)

The problem is that the way the mocking environment for those unit
tests is written is a bit fragile: it creates a special purpose
regcache (and sentinel's frame), using whatever is the current
inferior_ptid (usually null_ptid), and assumes get_current_regcache
will find that in the regcache::current_regcache list.

This commit changes the way the mock environment is created.  It
eliminates the special regcache and frame and instead creates a fuller
mock environment, with a custom mock target_ops, and then a mock
inferior and thread "running" on that target.

If there's already a running target when you type "maint selftest",
then we bail out, instead of pushing a new target on top of the
existing one (and thus killing the debug session).  I think that's OK,
because self tests are really mean to be run from a clean state right
after GDB is started.  I'm adding that skipping just as safe measure
just in case someone (as I've done it) types "maint selftest" on the
command line while already debugging something.

(In my multi-target branch, where this patch originated from, we don't
actually need to bail out, because there each inferior has its own
target stack).

Also, note that the current code was doing:

 current_inferior()->gdbarch = gdbarch;

without taking care to restore the previous gdbarch.  This means that
GDB's state was being left inconsistent after running the self tests,,
further supporting the point that there's probably not much
expectation that mixing "maint selftests" and regular debugging in the
same GDB invocation really works.

gdb/ChangeLog:
yyyy-mm-dd  Pedro Alves  <palves@redhat.com>

	* frame.c (create_test_frame): Delete.
	* frame.h (create_test_frame): Delete.
	* gdbarch-selftests.c: Include gdbthread.h and target.h.
	(class regcache_test): Delete.
	(test_target_has_registers, test_target_has_stack)
	(test_target_has_memory, test_target_prepare_to_store)
	(test_target_fetch_registers, test_target_store_registers): New
	functions.
	(test_target_ops): New class.
	(register_to_value_test): Error out if there's execution.  Create
	a fuller mock environment, with mock target_ops, inferior, address
	space, thread and inferior_ptid.
	* progspace.c (struct address_space): Move to ...
	* progspace.h (struct address_space): ... here.
	* regcache.h (regcache::~regcache, regcache::raw_write)
	[GDB_SELF_TEST]: No longer virtual.
	* target.c (default_thread_address_space)
	(default_thread_architecture): Make extern.
	* target.h (default_thread_architecture)
	(default_thread_address_space): Declare.
---
 gdb/frame.c             |  17 --------
 gdb/frame.h             |   8 ----
 gdb/gdbarch-selftests.c | 105 ++++++++++++++++++++++++++++++++++++++++--------
 gdb/progspace.c         |  12 ------
 gdb/progspace.h         |  11 +++++
 gdb/regcache.h          |  10 -----
 gdb/target.c            |  10 +----
 gdb/target.h            |  10 +++++
 8 files changed, 111 insertions(+), 72 deletions(-)

[1/3] Redesign mock environment for gdbarch selftests

Commit Message

Comments

Patch