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target factories, target open and multiple instances of targets

Currently, to open a target, with "target TARGET_NAME", GDB finds the
target_ops instance with "TARGET_NAME" as short name, and then calls
its target_ops::open virtual method. In reality, there's no actual
target/name lookup, a pointer to the target_ops object was associated
with the "target TARGET_NAME" command at add_target time (when GDB is
initialized), as the command's context.

This creates a chicken and egg situation. Consider the case of
wanting to open multiple remote connections. We want to be able to
have one remote target_ops instance per connection, but, if we're not
connected yet, so we don't yet have an instance to call target->open()
on...

This patch fixes this by separating out common info about a target_ops
to a separate structure (shortname, longname, doc), and changing the
add_target routine to take a reference to such an object instead of a
pointer to a target_ops, and a pointer to a factory function that is
responsible to open an instance of the corresponding target when the
user types "target TARGET_NAME".

-extern void add_target (struct target_ops *);
+extern void add_target (const target_info &info, target_open_ftype *func);

I.e. this factory function replaces the target_ops::open virtual
method.

For static/singleton targets, nothing changes, the target_open_ftype
function pushes the global target_ops instance on the target stack.
At target_close time, the connection is tor down, but the global
target_ops object remains live.

However, targets that support being open multiple times will make
their target_open_ftype routine allocate a new target_ops instance on
the heap [e.g., new remote_target()], and push that on the stack. At
target_close time, the new object is destroyed (by the
target_ops::close virtual method).

Both the core target and the remote targets will support being open
multiple times (others could/should too, but those were my stopping
point), but not in this patch yet. We need to get rid of more globals
first before that'd be useful.

Native targets are somewhat special, given find_default_run_target &
friends. Those routines also expect to return a target_ops pointer,
even before we've open the target. However, we'll never need more
than one instance of the native target, so we can assume/require that
native targets are global/simpletons, and have the backends register a
pointer to the native target_ops. Since all native targets inherit
inf_child_target, we can centralize that registration. See
add_inf_child_target, get_native_target/set_native_target and
find_default_run_target.

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

* aarch64-fbsd-nat.c (_initialize_aarch64_fbsd_nat): Use
add_inf_child_target.
* aarch64-linux-nat.c (_initialize_aarch64_linux_nat): Use
add_inf_child_target.
* aix-thread.c (aix_thread_target_info): New.
(aix_thread_target) <shortname, longname, doc>: Delete.
<info>: New.
* alpha-bsd-nat.c (_initialize_alphabsd_nat): Use
add_inf_child_target.
* alpha-linux-nat.c (_initialize_alpha_linux_nat): Use
add_inf_child_target.
* amd64-fbsd-nat.c (_initialize_amd64fbsd_nat): Use
add_inf_child_target.
* amd64-linux-nat.c (_initialize_amd64_linux_nat): Use
add_inf_child_target.
* amd64-nbsd-nat.c (_initialize_amd64nbsd_nat): Use
add_inf_child_target.
* amd64-obsd-nat.c (_initialize_amd64obsd_nat): Use
add_inf_child_target.
* arm-fbsd-nat.c (_initialize_arm_fbsd_nat): Use
add_inf_child_target.
* arm-linux-nat.c (_initialize_arm_linux_nat): Use
add_inf_child_target.
* arm-nbsd-nat.c (_initialize_arm_netbsd_nat): Use
add_inf_child_target.
* bfd-target.c (target_bfd_target_info): New.
(target_bfd) <shortname, longname, doc>: Delete.
<info>: New.
* bsd-kvm.c (bsd_kvm_target_info): New.
(bsd_kvm_target) <shortname, longname, doc>: Delete.
<info>: New.
(bsd_kvm_target::open): Rename to ...
(bsd_kvm_target_open): ... this. Adjust.
* bsd-uthread.c (bsd_uthread_target_info): New.
(bsd_uthread_target) <shortname, longname, doc>: Delete.
<info>: New.
* corefile.c (core_file_command): Adjust.
* corelow.c (core_target_info): New.
(core_target) <shortname, longname, doc>: Delete.
<info>: New.
(core_target::open): Rename to ...
(core_target_open): ... this. Adjust.
* ctf.c (ctf_target_info): New.
(ctf_target) <shortname, longname, doc>: Delete.
<info>: New.
(ctf_target::open): Rename to ...
(ctf_target_open): ... this.
(_initialize_ctf): Adjust.
* exec.c (exec_target_info): New.
(exec_target) <shortname, longname, doc>: Delete.
<info>: New.
(exec_target::open): Rename to ...
(exec_target_open): ... this.
* gdbcore.h (core_target_open): Declare.
* go32-nat.c (_initialize_go32_nat): Use add_inf_child_target.
* hppa-linux-nat.c (_initialize_hppa_linux_nat): Use
add_inf_child_target.
* hppa-nbsd-nat.c (_initialize_hppanbsd_nat): Use
add_inf_child_target.
* hppa-obsd-nat.c (_initialize_hppaobsd_nat): Use
add_inf_child_target.
* i386-darwin-nat.c (_initialize_i386_darwin_nat): Use
add_inf_child_target.
* i386-fbsd-nat.c (_initialize_i386fbsd_nat): Use
add_inf_child_target.
* i386-gnu-nat.c (_initialize_i386gnu_nat): Use
add_inf_child_target.
* i386-linux-nat.c (_initialize_i386_linux_nat): Use
add_inf_child_target.
* i386-nbsd-nat.c (_initialize_i386nbsd_nat): Use
add_inf_child_target.
* i386-obsd-nat.c (_initialize_i386obsd_nat): Use
add_inf_child_target.
* ia64-linux-nat.c (_initialize_ia64_linux_nat): Use
add_inf_child_target.
* inf-child.c (inf_child_target_info): New.
(inf_child_target::info): New.
(inf_child_open_target): Remove 'target' parameter. Use
get_native_target instead.
(inf_child_target::open): Delete.
(add_inf_child_target): New.
* inf-child.h (inf_child_target) <shortname, longname, doc, open>:
Delete.
<info>: New.
(add_inf_child_target): Declare.
(inf_child_open_target): Declare.
* linux-thread-db.c (thread_db_target_info): New.
(thread_db_target) <shortname, longname, doc>: Delete.
<info>: New.
* m32r-linux-nat.c (_initialize_m32r_linux_nat): Use
add_inf_child_target.
* m68k-bsd-nat.c (_initialize_m68kbsd_nat): Use
add_inf_child_target.
* m68k-linux-nat.c (_initialize_m68k_linux_nat): Use
add_inf_child_target.
* m88k-bsd-nat.c (_initialize_m88kbsd_nat): Use
add_inf_child_target.
* make-target-delegates (print_class): Adjust.
* mips-fbsd-nat.c (_initialize_mips_fbsd_nat): Use
add_inf_child_target.
* mips-linux-nat.c (_initialize_mips_linux_nat): Use
add_inf_child_target.
* mips-nbsd-nat.c (_initialize_mipsnbsd_nat): Use
add_inf_child_target.
* mips64-obsd-nat.c (_initialize_mips64obsd_nat): Use
add_inf_child_target.
* nto-procfs.c (nto_native_target_info): New.
(nto_procfs_target_native) <shortname, longname, doc>:
Delete.
<info>: New.
(nto_procfs_target_info): New.
(nto_procfs_target_procfs) <shortname, longname, doc>:
Delete.
<info>: New.
(init_procfs_targets): Adjust.
* ppc-fbsd-nat.c (_initialize_ppcfbsd_nat): Use
add_inf_child_target.
* ppc-linux-nat.c (_initialize_ppc_linux_nat): Use
add_inf_child_target.
* ppc-nbsd-nat.c (_initialize_ppcnbsd_nat): Use
add_inf_child_target.
* ppc-obsd-nat.c (_initialize_ppcobsd_nat): Use
add_inf_child_target.
* ravenscar-thread.c (ravenscar_target_info): New.
(ravenscar_thread_target) <shortname, longname, doc>:
Delete.
<info>: New.
* record-btrace.c (record_btrace_target_info):
(record_btrace_target) <shortname, longname, doc>: Delete.
<info>: New.
(record_btrace_target::open): Rename to ...
(record_btrace_target_open): ... this. Adjust.
* record-full.c (record_longname, record_doc): New.
(record_full_base_target) <shortname, longname, doc>: Delete.
<info>: New.
(record_full_target_info): New.
(record_full_target): <shortname>: Delete.
<info>: New.
(record_full_core_open_1, record_full_open_1): Update comments.
(record_full_base_target::open): Rename to ...
(record_full_open): ... this.
(cmd_record_full_restore): Update.
(_initialize_record_full): Update.
* remote-sim.c (remote_sim_target_info): New.
(gdbsim_target) <shortname, longname, doc>: Delete.
<info>: New.
(gdbsim_target::open): Rename to ...
(gdbsim_target_open): ... this.
(_initialize_remote_sim): Adjust.
* remote.c (remote_doc): New.
(remote_target_info): New.
(remote_target) <shortname, longname, doc>: Delete.
<info>: New.
(extended_remote_target_info): New.
(extended_remote_target) <shortname, longname, doc>: Delete.
<info>: New.
(remote_target::open_1): Make static. Adjust.
* rs6000-nat.c (_initialize_rs6000_nat): Use add_inf_child_target.
* s390-linux-nat.c (_initialize_s390_nat): Use
add_inf_child_target.
* sh-nbsd-nat.c (_initialize_shnbsd_nat): Use
add_inf_child_target.
* sol-thread.c (thread_db_target_info): New.
(sol_thread_target) <shortname, longname, doc>: Delete.
<info>: New.
* sparc-linux-nat.c (_initialize_sparc_linux_nat): Use
add_inf_child_target.
* sparc-nbsd-nat.c (_initialize_sparcnbsd_nat): Use
add_inf_child_target.
* sparc64-fbsd-nat.c (_initialize_sparc64fbsd_nat): Use
add_inf_child_target.
* sparc64-linux-nat.c (_initialize_sparc64_linux_nat): Use
add_inf_child_target.
* sparc64-nbsd-nat.c (_initialize_sparc64nbsd_nat): Use
add_inf_child_target.
* sparc64-obsd-nat.c (_initialize_sparc64obsd_nat): Use
add_inf_child_target.
* spu-linux-nat.c (_initialize_spu_nat): Use
add_inf_child_target.
* spu-multiarch.c (spu_multiarch_target_info): New.
(spu_multiarch_target) <shortname, longname, doc>: Delete.
<info>: New.
* target-delegates.c: Regenerate.
* target.c: Include <unordered_map>.
(target_ops_p): Delete.
(DEF_VEC_P(target_ops_p)): Delete.
(target_factories): New.
(test_target_info): New.
(test_target_ops::info): New.
(open_target): Adjust to use target_factories.
(add_target_with_completer): Rename to ...
(add_target): ... this. Change prototype. Register target_info
and open callback in target_factories. Register target_info in
command context instead of target_ops.
(add_target): Delete old implementation.
(add_deprecated_target_alias): Change prototype. Adjust.
(the_native_target): New.
(set_native_target, get_native_target): New.
(find_default_run_target): Use the_native_target.
(find_attach_target, find_run_target): Simplify.
(target_ops::open): Delete.
(dummy_target_info): New.
(dummy_target::shortname, dummy_target::longname)
(dummy_target::doc): Delete.
(dummy_target::info): New.
(debug_target::shortname, debug_target::longname)
(debug_target::doc): Delete.
(debug_target::info): New.
* target.h (struct target_info): New.
(target_ops::~target_ops): Add comment.
(target_ops::info): New.
(target_ops::shortname, target_ops::longname, target_ops::doc): No
longer virtual. Implement in terms of target_info.
(set_native_target, get_native_target): Declare.
(target_open_ftype): New.
(add_target, add_target_with_completer)
(add_deprecated_target_alias): Change prototype.
(test_target) <shortname, longname, doc>: Delete.
<info>: New.
* tilegx-linux-nat.c (_initialize_tile_linux_nat): Use
add_inf_child_target.
* tracefile-tfile.c (tfile_target_info): New.
(tfile_target) <shortname, longname, doc>: Delete.
<info>: New.
(tfile_target::open): Rename to ...
(tfile_target_open): ... this.
(_initialize_tracefile_tfile): Adjust.
* vax-bsd-nat.c (_initialize_vaxbsd_nat): Use
add_inf_child_target.
* windows-nat.c (_initialize_windows_nat): Use
add_inf_child_target.
* xtensa-linux-nat.c (_initialize_xtensa_linux_nat): Use
add_inf_child_target.

linux_nat_target: More low methods

This converts the remaining linux-nat.c hooks low_ methods like had
been started in a previous patch. The linux_nat_set_foo routines are
all gone with this.

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

* linux-nat.h (linux_nat_target) <low_new_thread,
low_delete_thread, low_new_fork, low_forget_process,
low_prepare_to_resume, low_siginfo_fixup, low_status_is_event>:
New virtual methods.
(linux_nat_set_new_thread, linux_nat_set_delete_thread)
(linux_nat_new_fork_ftype, linux_nat_set_new_fork)
(linux_nat_forget_process_ftype, linux_nat_set_forget_process)
(linux_nat_forget_process, linux_nat_set_siginfo_fixup)
(linux_nat_set_prepare_to_resume, linux_nat_set_status_is_event):
Delete.
* linux-fork.c (delete_fork): Adjust to call low method.
* linux-nat.c (linux_nat_new_thread, linux_nat_delete_thread)
(linux_nat_new_fork, linux_nat_forget_process_hook)
(linux_nat_prepare_to_resume, linux_nat_siginfo_fixup)
(linux_nat_status_is_event):
(linux_nat_target::follow_fork, lwp_free, add_lwp, detach_one_lwp)
(linux_resume_one_lwp_throw, linux_handle_extended_wait): Adjust
to call low method.
(sigtrap_is_event): Rename to ...
(linux_nat_target::low_status_is_event): ... this.
(linux_nat_set_status_is_event): Delete.
(save_stop_reason, linux_nat_wait_1)
(linux_nat_target::mourn_inferior, siginfo_fixup): Adjust to call
low methods.
(linux_nat_set_new_thread, linux_nat_set_delete_thread)
(linux_nat_set_new_fork, linux_nat_set_forget_process)
(linux_nat_forget_process, linux_nat_set_siginfo_fixup)
(linux_nat_set_prepare_to_resume): Delete.
* aarch64-linux-nat.c: All linux_nat_set_* callbacks converted to
low virtual methods.
* amd64-linux-nat.c: Likewise.
* arm-linux-nat.c: Likewise.
* i386-linux-nat.c: Likewise.
* ia64-linux-nat.c: Likewise.
* mips-linux-nat.c: Likewise.
* ppc-linux-nat.c: Likewise.
* s390-linux-nat.c: Likewise.
* sparc64-linux-nat.c: Likewise.
* x86-linux-nat.c: Likewise.
* x86-linux-nat.h: Include "nat/x86-linux.h".
(x86_linux_nat_target) <low_new_fork, low_forget_process,
low_prepare_to_resume, low_new_thread, low_delete_thread>:
Override methods.

target_ops: Use bool throughout

After the previous target_ops/C++ patches are all squashed and merged,
this one can go in separately.

This patch adjusts all the target methods to return bool instead of int
when they're returning a boolean.

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

* target.h (target_ops)
<stopped_by_sw_breakpoint, supports_stopped_by_sw_breakpoint,
stopped_by_hw_breakpoint, supports_stopped_by_hw_breakpoint,
stopped_by_watchpoint, have_continuable_watchpoint,
stopped_data_address, watchpoint_addr_within_range,
can_accel_watchpoint_condition, can_run, thread_alive,
has_all_memory, has_memory, has_stack, has_registers,
has_execution, can_async_p, is_async_p, supports_non_stop,
always_non_stop_p, can_execute_reverse, supports_multi_process,
supports_enable_disable_tracepoint,
supports_disable_randomization, supports_string_tracing,
supports_evaluation_of_breakpoint_conditions,
can_run_breakpoint_commands, filesystem_is_local,
can_download_tracepoint, get_trace_state_variable_value,
set_trace_notes, get_tib_address, use_agent, can_use_agent,
record_is_replaying, record_will_replay,
augmented_libraries_svr4_read>: Adjust to return bool.
* aarch64-linux-nat.c: All implementations adjusted.
* aix-thread.c: All implementations adjusted.
* arm-linux-nat.c: All implementations adjusted.
* breakpoint.c: All implementations adjusted.
* bsd-kvm.c: All implementations adjusted.
* bsd-uthread.c: All implementations adjusted.
* corelow.c: All implementations adjusted.
* ctf.c: All implementations adjusted.
* darwin-nat.c: All implementations adjusted.
* darwin-nat.h: All implementations adjusted.
* exec.c: All implementations adjusted.
* fbsd-nat.c: All implementations adjusted.
* fbsd-nat.h: All implementations adjusted.
* gnu-nat.c: All implementations adjusted.
* gnu-nat.h: All implementations adjusted.
* go32-nat.c: All implementations adjusted.
* ia64-linux-nat.c: All implementations adjusted.
* inf-child.c: All implementations adjusted.
* inf-child.h: All implementations adjusted.
* inf-ptrace.c: All implementations adjusted.
* inf-ptrace.h: All implementations adjusted.
* linux-nat.c: All implementations adjusted.
* linux-nat.h: All implementations adjusted.
* mips-linux-nat.c: All implementations adjusted.
* nto-procfs.c: All implementations adjusted.
* ppc-linux-nat.c: All implementations adjusted.
* procfs.c: All implementations adjusted.
* ravenscar-thread.c: All implementations adjusted.
* record-btrace.c: All implementations adjusted.
* record-full.c: All implementations adjusted.
* remote-sim.c: All implementations adjusted.
* remote.c: All implementations adjusted.
* s390-linux-nat.c: All implementations adjusted.
* sol-thread.c: All implementations adjusted.
* spu-multiarch.c: All implementations adjusted.
* target-delegates.c: All implementations adjusted.
* target.c: All implementations adjusted.
* target.h: All implementations adjusted.
* tracefile-tfile.c: All implementations adjusted.
* tracefile.c: All implementations adjusted.
* tracefile.h: All implementations adjusted.
* windows-nat.c: All implementations adjusted.
* x86-linux-nat.h: All implementations adjusted.
* x86-nat.h: All implementations adjusted.

target_ops/C++: The Hurd

Straightforward conversion. Not tested.

target_ops/C++: go32/DJGPP

Straightforward conversion. Build tested with a cross compiler.

target_ops/C++: NTO/QNX, nto-procfs.c

Straightforward conversion. Not tested.

target_ops/C++: bsd_kvm_add_target, BSD libkvm target

Straightforward conversion.

I considered making bsd_kvm_supply_pcb a virtual method, and then have
each port inherit bsd_kvm_target and override that method, but that
was resulting in lots of unjustified churn, so I left the function
pointer mechanism alone.

target_ops/C++: The rest of the BSD targets

The

$architecture x NetBSD/OpenBSD/FreeBSD

support matrix complicates things a bit. There's common BSD target
code, and there's common architecture-specific code shared between the
different BSDs. Current, all that is stiched together to form a final
target, via the i386bsd_target, x86bsd_target, fbsd_nat_add_target
functions etc.

This patch converts the rest of the BSD targets to C++ified target_ops.

Adds new obsd_nat_target and nbsd_nat_target targets similar to
fbsd_nat_target introduced a couple patches ago, a sparc_target mixin
similar to the one introduced in the previous patch for x86, and then
stiches everything together into final targets.

Unfortunately, I'm not able to test most of this. I was able to build
GDB for AMD64 NetBSD on the compile farm, but that's it.

target_ops/C++: Generic i386/AMD64 BSD targets

The

$architecture x NetBSD/OpenBSD/FreeBSD

support matrix complicates things a bit. There's common BSD target
code, and there's common architecture-specific code shared between the
different BSDs. Current, all that is stiched together to form a final
target, via the i386bsd_target, x86bsd_target, fbsd_nat_add_target
functions etc.

Introduces generic i386/AMD64 BSD targets, to be used as template
mixin to build a final target.

target_ops/C++: Base FreeBSD target

The

$architecture x NetBSD/OpenBSD/FreeBSD

support matrix complicates things a bit. There's common BSD target
code, and there's common architecture-specific code shared between the
different BSDs. Current, all that is stiched together to form a final
target, via the i386bsd_target, x86bsd_target, fbsd_nat_add_target
functions etc.

Introduces a fbsd_nat_target base/prototype target. To be used in
following patches.

target_ops/C++: Xtensa GNU/Linux

Straighforward conversion. Not tested.

target_ops/C++: Tile-Gx GNU/Linux

Straighforward conversion. Not tested.

target_ops/C++: SPU/Linux

Straighforward conversion.

target_ops/C++: SPARC GNU/Linux

Straighforward conversion.

target_ops/C++: s390 GNU/Linux

Straighforward conversion.

target_ops/C++: m68k GNU/Linux

Straighforward conversion. Not tested.

target_ops/C++: m32r GNU/Linux

Straighforward conversion. Not tested.

target_ops/C++: IA-64 GNU/Linux

Straighforward conversion. Not tested.

target_ops/C++: HP-PA GNU/Linux

Straighforward conversion. Not tested.

target_ops/C++: Aarch64 GNU/Linux

Straighforward conversion. Smoke tested on the compile farm.

target_ops/C++: ARM GNU/Linux

Straighforward conversion. Smoke tested on the compile farm.

target_ops/C++: AIX target

Straighforward conversion. Tested on AIX 7.2 on the compile farm.

target_ops/C++: linux_trad_target, MIPS and Alpha GNU/Linux

This converts the code in the new linux-nat-trad.h/c files, that was
split off of inf-ptrace.h/c recently, to a C++ base class, and makes
the MIPS and Alpha GNU/Linux ports use it.

Otherwise, it's a straighforward conversion.

I'd checked with a cross compiler that the MIPS port builds. I don't
have an Alpha compiler handy.

target_ops/C++: macOS/Darwin target

Straighforward conversion. I'd checked that this builds with a cross
compiler.

target_ops/C++: Windows targets

Straighforward conversion. I'd tested this with a cross compiler.

target_ops/C++: Solaris/procfs

Straighforward conversion. I'd tested this on a Solaris VM.

target_ops/C++: PPC/PPC64 GNU/Linux

Straighforward conversion. I'd tested this on the GCC compile farm.

target_ops/C++: GNU/Linux + x86/AMD64

This converts the x86/AMD64 GNU/Linux ports to C++ified target_ops.

- inf-child/"native" is converted to an actual base class
(inf_child_target), that is inherited by the linux-nat target.
inf_child_target will be inherited by all other native targets too,
of course, in the following patches.

- The old weird double-target linux_ops mechanism in linux-nat.c, is
gone, replaced by adding a few virtual methods to linux-nat.h's
target_ops, called low_XXX, that the concrete linux-nat
implementations override. Sort of like gdbserver's
linux_target_ops, but simpler, for requiring only one
target_ops-like hierarchy, which spares implementing the same method
twice when we need to forward the method to a low implementation.
The low target simply reimplements the target_ops method directly in
that case.

There are a few remaining linux-nat.c hooks that would be better
converted to low_ methods like above too. E.g.:

linux_nat_set_new_thread (t, x86_linux_new_thread);
linux_nat_set_new_fork (t, x86_linux_new_fork);
linux_nat_set_forget_process

That'll be done in a follow up patch.

- We can no longer use functions like x86_use_watchpoints to install
custom methods on an arbitrary base target. The patch replaces that
with a template mixin. See x86_nat_target in x86-nat.h. That will
be used by other non-Linux x86 targets in following patches.

- linux-thread-db is converted here too.

target_ops/C++: target remote-sim

Straighforward conversion.

target_ops/C++: remote/extended-remote targets

This is a first pass, just enough to C++ify target_ops.

A later pass will convert more free functions to methods, and make the
remote_state be truly per remote instance, allowing multiple
simultaneous instances of remote targets.