[PATCH 2/2] Class-ify ptid_t
Simon Marchi
simon.marchi@polymtl.ca
Wed Apr 5 19:44:00 GMT 2017
On 2017-04-05 11:47, Pedro Alves wrote:
> Hi Simon,
>
> Hmm, "unit tests or it didn't happen" ? :-)
Right, I don't have the unit test in GDB mindset yet. But of course,
it's a good idea, I'll do it.
> On 04/04/2017 07:32 PM, Simon Marchi wrote:
>> I grew a bit tired of using ptid_get_{lwp,pid,tid} and friends, so I
>> decided to make it a bit easier to use by making it a proper class.
>>
>> Because ptid_t is used in things that aren't constructed, it is not
>> possible to have a constructor. Instead I added a "build" static
>> method, which maps well to the current ptid_build anyway, and ptid_t
>> is
>> basically just a plain old data type with read-only methods. The
>> difference with before is that the fields are private, so it's not
>> possible to change a ptid_t field by mistake.
>>
>> The new methods of ptid_t map to existing functions/practice like
>> this:
>>
>> ptid_t::build (pid, lwp, tid) -> ptid_build (pid, lwp, tid)
>> ptid_t::build (pid) -> pid_to_ptid (pid)
>
> Not sure these two are an improvement. pid_to_ptid is the
> counterpart of ptid_is_pid, and that is lost with the
> overloading of ptid_t::build.
Would you prefer having a ptid_t::from_pid method instead? It would be
the counter part of ptid_t::is_pid. Or do you prefer if we keep the
current function?
>> ptid.is_pid () -> ptid_is_pid (ptid)
>> ptid == other -> ptid_equal (ptid, other)
>> ptid.is_null () -> ptid_equal (ptid, null_ptid)
>> ptid.is_any () -> ptid_equal (ptid, minus_one_ptid)
>> ptid.pid () -> ptid_get_pid (ptid)
>> ptid.lwp_p () -> ptid_lwp_p (ptid)
>> ptid.lwp () -> ptid_get_lwp (ptid)
>> ptid.tid_p () -> ptid_tid_p (ptid)
>> ptid.tid () -> ptid_get_tid (ptid)
>> ptid.matches (filter) -> ptid_match (ptid, filter)
>>
>> I've replaced the implementation of the existing functions with calls
>> to
>> the new methods. People are encouraged to gradually switch to using
>> the
>> ptid_t methods instead of the functions (or we can change them all in
>> one pass eventually).
>>
>> Also, I'm not sure if it's worth it (because of ptid_t's relatively
>> small size), but I have made the functions and methods take ptid_t
>> arguments by const reference instead of by value.
>
> I'd guess that the structure is still sufficiently small that passing
> by value would be a benefit (plus, it avoids inefficiency caused
> by the compiler having to assume that the references can alias),
> but OTOH, this structure is likely to grow with the multi-target
> work. Fine with me to go with what you have.
Ok.
>>
>> /* See ptid.h for these. */
>>
>> -ptid_t null_ptid = { 0, 0, 0 };
>> -ptid_t minus_one_ptid = { -1, 0, 0 };
>> +ptid_t null_ptid = ptid_t::build (0, 0, 0);
>> +ptid_t minus_one_ptid = ptid_t::build (-1, 0, 0);
>
> It's probably going to be worth it to sprinkle "constexpr"
> all over the new API. Helps with static_asserts in
> unit testing too. *cough* :-)
Ok, will look into it.
>> -struct ptid
>> +class ptid_t
>> {
>> +public:
>> + static ptid_t build (int pid, long lwp = 0, long tid = 0)
>> + {
>> + ptid_t ptid;
>> +
>> + ptid.m_pid = pid;
>> + ptid.m_lwp = lwp;
>> + ptid.m_tid = tid;
>> +
>> + return ptid;
>> + }
>> +
>> + bool is_pid () const
>> + {
>> + if (is_any () || is_null())
>
> Missing space after "null".
Thanks, fixed
> Wonder about migrating/copying the comments API comments to
> the methods, if these are the entry points that people should
> be looking at going forward.
Right, it would make sense.
>> + return false;
>> +
>> + return m_lwp == 0 && m_tid == 0;
>> + }
>> +
>
>> diff --git a/gdb/gdbserver/server.c b/gdb/gdbserver/server.c
>> index 4bc7f71b00..1287114cc1 100644
>> --- a/gdb/gdbserver/server.c
>> +++ b/gdb/gdbserver/server.c
>> @@ -2654,7 +2654,9 @@ handle_v_cont (char *own_buf)
>> char *p, *q;
>> int n = 0, i = 0;
>> struct thread_resume *resume_info;
>> - struct thread_resume default_action = {{0}};
>> + struct thread_resume default_action = {
>> + .thread = null_ptid,
>> + };
>
> Note that C99 designated initializers are not valid C++11.
> Not sure whether any compiler _doesn't_ support them though.
Ok. But anyway C++11-style initialization is probably better anyway.
Is the following ok?
struct thread_resume default_action { null_ptid };
Thanks,
Simon
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