Here is the long-threatened patch that makes tracepoints into a type of 
breakpoint. Conceptually, the change is straightforward; we add a new 
breakpoint type bp_tracepoint, add three tracepoint-specific fields to 
struct breakpoint, special-case the breakpoint code here and there, and 
remove the old tracepoint manipulation code. In general, tracepoints 
look like regular breakpoints, except that they are only inserted by the 
tstart command, and the program never stops at any of them.

Some of the details are messy; for instance, one could argue that 
"delete trace" and "info trace" are still useful, as versions of 
breakpoint commands that filter out non-tracepoints, but it seems unduly 
pedantic to have "delete trace <num>" on a non-tracepoint be an error. 
So I retained old behavior for the no-argument case, and otherwise just 
forwarded into general breakpoint commands. Likewise, one could make a 
case that breakpoint commands and tracepoint actions should become the 
same field, but that will take more thought to get right, and makes more 
sense as a later change. So in the meantime I prefix the actions in 
"info break" with an 'A' to make clear that they are not breakpoint 
commands.

Another unresolved issue is locations. Tracepoints can now have multiple 
locations, but unlike breakpoint numbers, tracepoint numbers are part of 
the tracing protocol, and it's not clear whether "bp.loc"-style numbers 
should be added to the protocol, or a new numbering system introduced 
instead.

I tested this on native Linux and show no regressions, plus it all works 
well with a CodeSourcery customer's target that supports tracepoints. 
Insight also still works. Since this is rather a large patch, I'll give 
people a few days to kibitz before committing. Note that there are 
multiple new features in the pipeline exploiting breakpoint-ness of 
tracepoints, so there will be several chances to fix up minor problems.

Stan

2009-03-27  Stan Shebs  <stan@codesourcery.com>

    Make tracepoints into a type of breakpoint.
    * breakpoint.h (enum bptype): Add bp_tracepoint.
    (struct breakpoint): Add fields step_count, pass_count, actions.
    (get_tracepoint, get_tracepoint_by_number): Declare.
    (all_tracepoints): Declare.
    * breakpoint.c: Include tracepoint.h, readline.h.
    (ALL_TRACEPOINTS): Move here from tracepoint.c.
    (tracepoint_count): Ditto.
    (should_be_inserted): GDB does not insert tracepoints itself.
    (print_it_typical): Add tracepoint case.
    (bpstat_what): Ditto.
    (print_one_breakpoint_location): Ditto, and add printing for
    pass count, step count, and action list.
    (user_settable_breakpoint): Add tracepoint case.
    (allocate_bp_location): Ditto.
    (set_breakpoint_location_function): Ditto.
    (disable_breakpoints_in_shlibs): Ditto.
    (mention): Ditto.
    (break_command_really): Add argument traceflag, use to choose
    basic breakpoint type.
    (break_command_1): Pass extra argument.
    (set_breakpoint, handle_gnu_v3_exceptions): Ditto.
    (breakpoint_re_set_one): Add tracepoint case.
    (disable_command, enable_command): Ditto.
    (set_tracepoint_count): Move here from tracepoint.c.
    (trace_command): Move here from tracepoint.c and use
    break_command_really.
    (tracepoints_info): Move here from tracepoint.c and call
    breakpoints_info.
    (enable_trace_command): Move here from tracepoint.c and call
    enable_command.
    (disable_trace_command): Move here from tracepoint.c and call
    disable_command.
    (delete_trace_command): Move here from tracepoint.c and call
    delete_breakpoint.
    (trace_pass_command): Move here from tracepoint.c.
    (get_tracepoint_by_number): Ditto.
    (tracepoint_save_command): Ditto.
    (get_tracepoint): New function.
    (all_tracepoints): New function.
    (_initialize_breakpoint): Move tracepoint init from tracepoint.c,
    deprecate "enable trace" and "disable trace" commands.
    * tracepoint.h (struct tracepoint): Remove.
    (tracepoint_chain): Remove decl.
    (deprecated_create_tracepoint_hook): Remove decl.
    (deprecated_delete_tracepoint_hook): Remove decl.
    (deprecated_modify_tracepoint_hook): Remove decl.
    (ALL_TRACEPOINTS, ALL_TRACEPOINTS_SAFE): Remove.
    (free_actions): Update signature.
    (validate_actionline): Update signature.
    * tracepoint.c: Include breakpoint.h.
    (tracepoint_chain, tracepoint_count): Remove.
    (free_actions, make_cleanup_free_actions): Update signature.
    (trace_command, set_raw_tracepoint): Remove.
    (trace_mention): Remove.
    (tracepoints_info): Remove.
    (tracepoint_operation, map_args_over_tracepoints): Remove.
    (get_tracepoint_by_number): Remove.
    (enable_trace_command, disable_trace_command): Remove.
    (delete_trace_command, trace_pass_command): Remove.
    (trace_actions_command, read_actions): Update signature.
    (validate_actionline): Update signature, use bp loc.
    (encode_actions): Ditto.
    (download_tracepoint): New function, body of trace_start_command.
    (trace_start_command): Call it, use all_tracepoints.
    (tracepoint_save_command): Remove.
    (tracepoint_dump_command): Use get_tracepoint.
    (_initialize_tracepoint): Move command definitions to breakpoint.c.

    doc/
    * gdb.texinfo (Tracepoints): Describe tracepoints as a
    special case of breakpoints.
    (Enable and Disable Tracepoints): Mention deprecation.
    (Listing Tracepoints): Update description and example.

    testsuite/
    * gdb.trace/actions.exp: Update to match new info trace format.
    * gdb.trace/deltrace.exp: Ditto.
    * gdb.trace/infotrace.exp: Ditto.
    * gdb.trace/passcount.exp: Ditto.
    * gdb.trace/save-trace.exp: Ditto.
    * gdb.trace/while-stepping.exp: Ditto.
    * gdb.trace/tracecmd.exp: Ditto, plus don't allow pending option.

    gdbtk/
    * generic/gdbtk-bp.c (gdb_actions_command): Update to handle
    tracepoints as breakpoints.
    (gdb_get_tracepoint_info): Ditto, plus use get_tracepoint and
    breakpoint locations.
    (tracepoint_exists): Ditto, plus use all_tracepoints.