comment fixes

This fixes up a few mildly erroneous comments in probe.h.

2014-03-03  Tom Tromey  <tromey@redhat.com>

	* probe.h (parse_probes, find_probe_by_pc)
	(find_probes_in_objfile): Fix comments.
change probes to be program-space-independent

This changes the probes to be independent of the program space.

After this, when a probe's address is needed, it is determined by
applying offsets at the point of use.

This introduces a bound_probe object, similar to bound minimal
symbols.  Objects of this type are used when it's necessary to pass a
probe and its corresponding objfile.

This removes the backlink from probe to objfile, which was primarily
used to fetch the architecture to use.

This adds a get_probe_address function which calls a probe method to
compute the probe's relocated address.  Similarly, it adds an objfile
parameter to the semaphore methods so they can do the relocation
properly as well.

2014-03-03  Tom Tromey  <tromey@redhat.com>

	* break-catch-throw.c (fetch_probe_arguments): Use bound probes.
	* breakpoint.c (create_longjmp_master_breakpoint): Use
	get_probe_address.
	(add_location_to_breakpoint, bkpt_probe_insert_location)
	(bkpt_probe_remove_location): Update.
	* breakpoint.h (struct bp_location) <probe>: Now a bound_probe.
	* elfread.c (elf_symfile_relocate_probe): Remove.
	(elf_probe_fns): Update.
	(insert_exception_resume_breakpoint): Change type of "probe"
	parameter to bound_probe.
	(check_exception_resume): Update.
	* objfiles.c (objfile_relocate1): Don't relocate probes.
	* probe.c (bound_probe_s): New typedef.
	(parse_probes): Use get_probe_address.  Set sal's objfile.
	(find_probe_by_pc): Return a bound_probe.
	(collect_probes): Return a VEC(bound_probe_s).
	(compare_probes): Update.
	(gen_ui_out_table_header_info): Change type of "probes"
	parameter.  Update.
	(info_probes_for_ops): Update.
	(get_probe_address): New function.
	(probe_safe_evaluate_at_pc): Update.
	* probe.h (struct probe_ops) <get_probe_address>: New field.
	<set_semaphore, clear_semaphore>: Add objfile parameter.
	(struct probe) <objfile>: Remove field.
	<arch>: New field.
	<address>: Update comment.
	(struct bound_probe): New.
	(find_probe_by_pc): Return a bound_probe.
	(get_probe_address): Declare.
	* solib-svr4.c (struct probe_and_action) <address>: New field.
	(hash_probe_and_action, equal_probe_and_action): Update.
	(register_solib_event_probe): Add address parameter.
	(solib_event_probe_at): Update.
	(svr4_create_probe_breakpoints): Add objfile parameter.  Use
	get_probe_address.
	* stap-probe.c (struct stap_probe) <sem_addr>: Update comment.
	(stap_get_probe_address): New function.
	(stap_can_evaluate_probe_arguments, compute_probe_arg)
	(compile_probe_arg): Update.
	(stap_set_semaphore, stap_clear_semaphore): Compute semaphore's
	address.
	(handle_stap_probe): Don't relocate the probe.
	(stap_relocate): Remove.
	(stap_gen_info_probes_table_values): Update.
	(stap_probe_ops): Remove stap_relocate.
	* symfile-debug.c (debug_sym_relocate_probe): Remove.
	(debug_sym_probe_fns): Update.
	* symfile.h (struct sym_probe_fns) <sym_relocate_probe>: Remove.
	* symtab.c (init_sal): Use memset.
	* symtab.h (struct symtab_and_line) <objfile>: New field.
	* tracepoint.c (start_tracing, stop_tracing): Update.
move probes to be per-bfd

This patch moves the probe data from the objfile to the per-BFD
object.  This lets the probes be shared between different inferiors
(and different objfiles when dlmopen is in use, should gdb ever handle
that).

2014-03-03  Tom Tromey  <tromey@redhat.com>

	* elfread.c (probe_key): Change to bfd_data.
	(elf_get_probes, probe_key_free, _initialize_elfread): Probes are
	now per-BFD, not per-objfile.
	* stap-probe.c (stap_probe_destroy): Update comment.
	(handle_stap_probe): Allocate on the per-BFD obstack.
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