Class-ify ptid_t

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.  The fields are now
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 (pid, lwp, tid) -> ptid_build (pid, lwp, tid)
  ptid_t (pid) -> pid_to_ptid (pid)
  ptid.is_pid () -> ptid_is_pid (ptid)
  ptid == other -> ptid_equal (ptid, other)
  ptid != other -> !ptid_equal (ptid, other)
  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.

gdb/ChangeLog:

	* common/ptid.h (struct ptid): Change to...
	(class ptid_t): ... this.
	<ptid_t>: New constructors.
	<pid, lwp_p, lwp, tid_p, tid, is_pid, operator==, operator!=,
	matches>: New methods.
	<make_null, make_minus_one>: New static methods.
	<pid>: Rename to...
	<m_pid>: ...this.
	<lwp>: Rename to...
	<m_lwp>: ...this.
	<tid>: Rename to...
	<m_tid>: ...this.
	(ptid_build, ptid_get_pid, ptid_get_lwp, ptid_get_tid, ptid_equal,
	ptid_is_pid, ptid_lwp_p, ptid_tid_p, ptid_match): Take ptid arguments
	as references, move comment to class ptid_t.
	* common/ptid.c (null_ptid, minus_one_ptid): Initialize with
	ptid_t static methods.
	(ptid_build, pid_to_ptid, ptid_get_pid, ptid_get_tid,
	ptid_equal, ptid_is_pid, ptid_lwp_p, ptid_tid_p, ptid_match):
	Take ptid arguments as references, implement using ptid_t methods.
	* unittests/ptid-selftests.c: New file.
	* Makefile.in (SUBDIR_UNITTESTS_SRCS): Add
	unittests/ptid-selftests.c.
	(SUBDIR_UNITTESTS_OBS): Add unittests/ptid-selftests.o.

gdb/gdbserver/ChangeLog:

	* server.c (handle_v_cont): Initialize thread_resume::thread
	with null_ptid.

7 files changed, 350 insertions, 77 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index e906b87..0f36e84 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,30 @@
+2017-04-06  Simon Marchi  <simon.marchi@ericsson.com>
+
+	* common/ptid.h (struct ptid): Change to...
+	(class ptid_t): ... this.
+	<ptid_t>: New constructors.
+	<pid, lwp_p, lwp, tid_p, tid, is_pid, operator==, operator!=,
+	matches>: New methods.
+	<make_null, make_minus_one>: New static methods.
+	<pid>: Rename to...
+	<m_pid>: ...this.
+	<lwp>: Rename to...
+	<m_lwp>: ...this.
+	<tid>: Rename to...
+	<m_tid>: ...this.
+	(ptid_build, ptid_get_pid, ptid_get_lwp, ptid_get_tid, ptid_equal,
+	ptid_is_pid, ptid_lwp_p, ptid_tid_p, ptid_match): Take ptid arguments
+	as references, move comment to class ptid_t.
+	* common/ptid.c (null_ptid, minus_one_ptid): Initialize with
+	ptid_t static methods.
+	(ptid_build, pid_to_ptid, ptid_get_pid, ptid_get_tid,
+	ptid_equal, ptid_is_pid, ptid_lwp_p, ptid_tid_p, ptid_match):
+	Take ptid arguments as references, implement using ptid_t methods.
+	* unittests/ptid-selftests.c: New file.
+	* Makefile.in (SUBDIR_UNITTESTS_SRCS): Add
+	unittests/ptid-selftests.c.
+	(SUBDIR_UNITTESTS_OBS): Add unittests/ptid-selftests.o.
+
 2017-04-06  Thomas Preud'homme  <thomas.preudhomme@arm.com>
 
 	* python/python.c (python_run_simple_file): Cast mode literal to
diff --git a/gdb/Makefile.in b/gdb/Makefile.in
index 479d273..23e4bed 100644
--- a/gdb/Makefile.in
+++ b/gdb/Makefile.in
@@ -525,11 +525,13 @@ SUBDIR_PYTHON_CFLAGS =
 
 SUBDIR_UNITTESTS_SRCS = \
 	unittests/function-view-selftests.c \
-	unittests/offset-type-selftests.c
+	unittests/offset-type-selftests.c \
+	unittests/ptid-selftests.c
 
 SUBDIR_UNITTESTS_OBS = \
 	function-view-selftests.o \
-	offset-type-selftests.o
+	offset-type-selftests.o \
+	ptid-selftests.o
 
 # Opcodes currently live in one of two places.  Either they are in the
 # opcode library, typically ../opcodes, or they are in a header file
diff --git a/gdb/common/ptid.c b/gdb/common/ptid.c
index b56971b..81f16d0 100644
--- a/gdb/common/ptid.c
+++ b/gdb/common/ptid.c
@@ -22,20 +22,15 @@
 
 /* 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::make_null ();
+ptid_t minus_one_ptid = ptid_t::make_minus_one ();
 
 /* See ptid.h.  */
 
 ptid_t
 ptid_build (int pid, long lwp, long tid)
 {
-  ptid_t ptid;
-
-  ptid.pid = pid;
-  ptid.lwp = lwp;
-  ptid.tid = tid;
-  return ptid;
+  return ptid_t (pid, lwp, tid);
 }
 
 /* See ptid.h.  */
@@ -43,81 +38,69 @@ ptid_build (int pid, long lwp, long tid)
 ptid_t
 pid_to_ptid (int pid)
 {
-  return ptid_build (pid, 0, 0);
+  return ptid_t (pid);
 }
 
 /* See ptid.h.  */
 
 int
-ptid_get_pid (ptid_t ptid)
+ptid_get_pid (const ptid_t &ptid)
 {
-  return ptid.pid;
+  return ptid.pid ();
 }
 
 /* See ptid.h.  */
 
 long
-ptid_get_lwp (ptid_t ptid)
+ptid_get_lwp (const ptid_t &ptid)
 {
-  return ptid.lwp;
+  return ptid.lwp ();
 }
 
 /* See ptid.h.  */
 
 long
-ptid_get_tid (ptid_t ptid)
+ptid_get_tid (const ptid_t &ptid)
 {
-  return ptid.tid;
+  return ptid.tid ();
 }
 
 /* See ptid.h.  */
 
 int
-ptid_equal (ptid_t ptid1, ptid_t ptid2)
+ptid_equal (const ptid_t &ptid1, const ptid_t &ptid2)
 {
-  return (ptid1.pid == ptid2.pid
-	  && ptid1.lwp == ptid2.lwp
-	  && ptid1.tid == ptid2.tid);
+  return ptid1 == ptid2;
 }
 
 /* See ptid.h.  */
 
 int
-ptid_is_pid (ptid_t ptid)
+ptid_is_pid (const ptid_t &ptid)
 {
-  if (ptid_equal (minus_one_ptid, ptid)
-      || ptid_equal (null_ptid, ptid))
-    return 0;
-
-  return (ptid_get_lwp (ptid) == 0 && ptid_get_tid (ptid) == 0);
+  return ptid.is_pid ();
 }
 
 /* See ptid.h.  */
 
 int
-ptid_lwp_p (ptid_t ptid)
+ptid_lwp_p (const ptid_t &ptid)
 {
-  return (ptid_get_lwp (ptid) != 0);
+  return ptid.lwp_p ();
 }
 
 /* See ptid.h.  */
 
 int
-ptid_tid_p (ptid_t ptid)
+ptid_tid_p (const ptid_t &ptid)
 {
-  return (ptid_get_tid (ptid) != 0);
+  return ptid.tid_p ();
 }
 
+/* See ptid.h.  */
+
 int
-ptid_match (ptid_t ptid, ptid_t filter)
+ptid_match (const ptid_t &ptid, const ptid_t &filter)
 {
-  if (ptid_equal (filter, minus_one_ptid))
-    return 1;
-  if (ptid_is_pid (filter)
-      && ptid_get_pid (ptid) == ptid_get_pid (filter))
-    return 1;
-  else if (ptid_equal (ptid, filter))
-    return 1;
-
-  return 0;
+  return ptid.matches (filter);
 }
diff --git a/gdb/common/ptid.h b/gdb/common/ptid.h
index 337bfb0..70f5199 100644
--- a/gdb/common/ptid.h
+++ b/gdb/common/ptid.h
@@ -32,65 +32,168 @@
    thread_stratum target that might want to sit on top.
 */
 
-struct ptid
+class ptid_t
 {
+public:
+  /* Must have a trivial defaulted default constructor so that the
+     type remains POD.  */
+  ptid_t () noexcept = default;
+
+  /* Make a ptid given the necessary PID, LWP, and TID components.
+
+     A ptid with only a PID (LWP and TID equal to zero) is usually used to
+     represent a whole process, including all its lwps/threads.  */
+
+  explicit constexpr ptid_t (int pid, long lwp = 0, long tid = 0)
+    : m_pid (pid), m_lwp (lwp), m_tid (tid)
+  {}
+
+  /* Fetch the pid (process id) component from the ptid.  */
+
+  constexpr int pid () const
+  { return m_pid; }
+
+  /* Return true if the ptid's lwp member is non-zero.  */
+
+  constexpr bool lwp_p () const
+  { return m_lwp != 0; }
+
+  /* Fetch the lwp (lightweight process) component from the ptid.  */
+
+  constexpr long lwp () const
+  { return m_lwp; }
+
+  /* Return true if the ptid's tid member is non-zero.  */
+
+  constexpr bool tid_p () const
+  { return m_tid != 0; }
+
+  /* Fetch the tid (thread id) component from a ptid.  */
+
+  constexpr long tid () const
+  { return m_tid; }
+
+  /* Return true if the ptid represents a whole process, including all its
+     lwps/threads.  Such ptids have the form of (pid, 0, 0), with
+     pid != -1.  */
+
+  constexpr bool is_pid () const
+  {
+    return (*this != make_null ()
+	    && *this != make_minus_one ()
+	    && m_lwp == 0
+	    && m_tid == 0);
+  }
+
+  /* Compare two ptids to see if they are equal.  */
+
+  constexpr bool operator== (const ptid_t &other) const
+  {
+    return (m_pid == other.m_pid
+	    && m_lwp == other.m_lwp
+	    && m_tid == other.m_tid);
+  }
+
+  /* Compare two ptids to see if they are different.  */
+
+  constexpr bool operator!= (const ptid_t &other) const
+  {
+    return !(*this == other);
+  }
+
+  /* Return true if the ptid matches FILTER.  FILTER can be the wild
+     card MINUS_ONE_PTID (all ptids match it); can be a ptid representing
+     a process (ptid.is_pid () returns true), in which case, all lwps and
+     threads of that given process match, lwps and threads of other
+     processes do not; or, it can represent a specific thread, in which
+     case, only that thread will match true.  The ptid must represent a
+     specific LWP or THREAD, it can never be a wild card.  */
+
+  constexpr bool matches (const ptid_t &filter) const
+  {
+    return (/* If filter represents any ptid, it's always a match.  */
+	    filter == make_minus_one ()
+	    /* If filter is only a pid, any ptid with that pid
+	       matches.  */
+	    || (filter.is_pid () && m_pid == filter.pid ())
+
+	    /* Otherwise, this ptid only matches if it's exactly equal
+	       to filter.  */
+	    || *this == filter);
+  }
+
+  /* Make a null ptid.  */
+
+  static constexpr ptid_t make_null ()
+  { return ptid_t (0, 0, 0); }
+
+  /* Make a minus one ptid.  */
+
+  static constexpr ptid_t make_minus_one ()
+  { return ptid_t (-1, 0, 0); }
+
+private:
   /* Process id.  */
-  int pid;
+  int m_pid;
 
   /* Lightweight process id.  */
-  long lwp;
+  long m_lwp;
 
   /* Thread id.  */
-  long tid;
+  long m_tid;
 };
 
-typedef struct ptid ptid_t;
-
 /* The null or zero ptid, often used to indicate no process. */
+
 extern ptid_t null_ptid;
 
 /* The (-1,0,0) ptid, often used to indicate either an error condition
    or a "don't care" condition, i.e, "run all threads."  */
+
 extern ptid_t minus_one_ptid;
 
-/* Make a ptid given the necessary PID, LWP, and TID components.  */
-ptid_t ptid_build (int pid, long lwp, long tid);
 
-/* Make a new ptid from just a pid.  This ptid is usually used to
-   represent a whole process, including all its lwps/threads.  */
-ptid_t pid_to_ptid (int pid);
+/* The following functions are kept for backwards compatibility.  The use of
+   the ptid_t methods is preferred.  */
+
+/* See ptid_t::ptid_t.  */
+
+extern ptid_t ptid_build (int pid, long lwp, long tid);
+
+/* See ptid_t::ptid_t.  */
+
+extern ptid_t pid_to_ptid (int pid);
+
+/* See ptid_t::pid.  */
+
+extern int ptid_get_pid (const ptid_t &ptid);
+
+/* See ptid_t::lwp.  */
+
+extern long ptid_get_lwp (const ptid_t &ptid);
+
+/* See ptid_t::tid.  */
+
+extern long ptid_get_tid (const ptid_t &ptid);
+
+/* See ptid_t::operator== and ptid_t::operator!=.  */
 
-/* Fetch the pid (process id) component from a ptid.  */
-int ptid_get_pid (ptid_t ptid);
+extern int ptid_equal (const ptid_t &ptid1, const ptid_t &ptid2);
 
-/* Fetch the lwp (lightweight process) component from a ptid.  */
-long ptid_get_lwp (ptid_t ptid);
+/* See ptid_t::is_pid.  */
 
-/* Fetch the tid (thread id) component from a ptid.  */
-long ptid_get_tid (ptid_t ptid);
+extern int ptid_is_pid (const ptid_t &ptid);
 
-/* Compare two ptids to see if they are equal.  */
-int ptid_equal (ptid_t ptid1, ptid_t ptid2);
+/* See ptid_t::lwp_p.  */
 
-/* Returns true if PTID represents a whole process, including all its
-   lwps/threads.  Such ptids have the form of (pid,0,0), with pid !=
-   -1.  */
-int ptid_is_pid (ptid_t ptid);
+extern int ptid_lwp_p (const ptid_t &ptid);
 
-/* Return true if PTID's lwp member is non-zero.  */
-int ptid_lwp_p (ptid_t ptid);
+/* See ptid_t::tid_p.  */
 
-/* Return true if PTID's tid member is non-zero.  */
-int ptid_tid_p (ptid_t ptid);
+extern int ptid_tid_p (const ptid_t &ptid);
 
-/* Returns true if PTID matches filter FILTER.  FILTER can be the wild
-   card MINUS_ONE_PTID (all ptid match it); can be a ptid representing
-   a process (ptid_is_pid returns true), in which case, all lwps and
-   threads of that given process match, lwps and threads of other
-   processes do not; or, it can represent a specific thread, in which
-   case, only that thread will match true.  PTID must represent a
-   specific LWP or THREAD, it can never be a wild card.  */
+/* See ptid_t::matches.  */
 
-extern int ptid_match (ptid_t ptid, ptid_t filter);
+extern int ptid_match (const ptid_t &ptid, const ptid_t &filter);
 
 #endif
diff --git a/gdb/gdbserver/ChangeLog b/gdb/gdbserver/ChangeLog
index 9b0c887..8b1adfe 100644
--- a/gdb/gdbserver/ChangeLog
+++ b/gdb/gdbserver/ChangeLog
@@ -1,3 +1,8 @@
+2017-04-06  Simon Marchi  <simon.marchi@ericsson.com>
+
+	* server.c (handle_v_cont): Initialize thread_resume::thread
+	with null_ptid.
+
 2017-04-05  Pedro Alves  <palves@redhat.com>
 
 	* configure: Regenerate.
diff --git a/gdb/gdbserver/server.c b/gdb/gdbserver/server.c
index 51f6a28..9cc6145 100644
--- a/gdb/gdbserver/server.c
+++ b/gdb/gdbserver/server.c
@@ -2654,7 +2654,7 @@ 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 { null_ptid };
 
   /* Count the number of semicolons in the packet.  There should be one
      for every action.  */
diff --git a/gdb/unittests/ptid-selftests.c b/gdb/unittests/ptid-selftests.c
new file mode 100644
index 0000000..5fc2ca6
--- /dev/null
+++ b/gdb/unittests/ptid-selftests.c
@@ -0,0 +1,153 @@
+/* Self tests for ptid_t for GDB, the GNU debugger.
+
+   Copyright (C) 2017 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include "defs.h"
+#include "common/ptid.h"
+#include <type_traits>
+
+namespace selftests {
+namespace ptid {
+
+/* Check that the ptid_t class is POD.
+
+   This is a requirement for as long as we have ptids embedded in
+   structures allocated with malloc. */
+
+static_assert (std::is_pod<ptid_t>::value, "ptid_t is POD");
+
+/* We want to avoid implicit conversion from int to ptid_t.  */
+
+static_assert (!std::is_convertible<int, ptid_t>::value,
+	       "constructor is explicit");
+
+/* Build some useful ptids.  */
+
+static constexpr ptid_t pid = ptid_t (1);
+static constexpr ptid_t lwp = ptid_t (1, 2, 0);
+static constexpr ptid_t tid = ptid_t (1, 0, 2);
+static constexpr ptid_t both = ptid_t (1, 2, 2);
+
+/* Build some constexpr version of null_ptid and minus_one_ptid to use in
+   static_assert.  Once the real ones are made constexpr, we can get rid of
+   these.  */
+
+static constexpr ptid_t null = ptid_t::make_null ();
+static constexpr ptid_t minus_one = ptid_t::make_minus_one ();
+
+/* Verify pid.  */
+
+static_assert (pid.pid () == 1, "pid's pid is right");
+static_assert (lwp.pid () == 1, "lwp's pid is right");
+static_assert (tid.pid () == 1, "tid's pid is right");
+static_assert (both.pid () == 1, "both's pid is right");
+
+/* Verify lwp_p.  */
+
+static_assert (!pid.lwp_p (), "pid's lwp_p is right");
+static_assert (lwp.lwp_p (), "lwp's lwp_p is right");
+static_assert (!tid.lwp_p (), "tid's lwp_p is right");
+static_assert (both.lwp_p (), "both's lwp_p is right");
+
+/* Verify lwp.  */
+
+static_assert (pid.lwp () == 0, "pid's lwp is right");
+static_assert (lwp.lwp () == 2, "lwp's lwp is right");
+static_assert (tid.lwp () == 0, "tid's lwp is right");
+static_assert (both.lwp () == 2, "both's lwp is right");
+
+/* Verify tid_p.  */
+
+static_assert (!pid.tid_p (), "pid's tid_p is right");
+static_assert (!lwp.tid_p (), "lwp's tid_p is right");
+static_assert (tid.tid_p (), "tid's tid_p is right");
+static_assert (both.tid_p (), "both's tid_p is right");
+
+/* Verify tid.  */
+
+static_assert (pid.tid () == 0, "pid's tid is right");
+static_assert (lwp.tid () == 0, "lwp's tid is right");
+static_assert (tid.tid () == 2, "tid's tid is right");
+static_assert (both.tid () == 2, "both's tid is right");
+
+/* Verify is_pid.  */
+
+static_assert (pid.is_pid (), "pid is a pid");
+static_assert (!lwp.is_pid (), "lwp isn't a pid");
+static_assert (!tid.is_pid (), "tid isn't a pid");
+static_assert (!both.is_pid (), "both isn't a pid");
+static_assert (!null.is_pid (), "null ptid isn't a pid");
+static_assert (!minus_one.is_pid (), "minus one ptid isn't a pid");
+
+/* Verify operator ==.  */
+
+static_assert (pid == ptid_t (1, 0, 0), "pid operator== is right");
+static_assert (lwp == ptid_t (1, 2, 0), "lwp operator== is right");
+static_assert (tid == ptid_t (1, 0, 2), "tid operator== is right");
+static_assert (both == ptid_t (1, 2, 2), "both operator== is right");
+
+/* Verify operator !=.  */
+
+static_assert (pid != ptid_t (2, 0, 0), "pid isn't equal to a different pid");
+static_assert (pid != lwp, "pid isn't equal to one of its thread");
+static_assert (lwp != tid, "lwp isn't equal to tid");
+static_assert (both != lwp, "both isn't equal to lwp");
+static_assert (both != tid, "both isn't equal to tid");
+
+/* Verify matches against minus_one.  */
+
+static_assert (pid.matches (minus_one), "pid matches minus one");
+static_assert (lwp.matches (minus_one), "lwp matches minus one");
+static_assert (tid.matches (minus_one), "tid matches minus one");
+static_assert (both.matches (minus_one), "both matches minus one");
+
+/* Verify matches against pid.  */
+
+static_assert (pid.matches (pid), "pid matches pid");
+static_assert (lwp.matches (pid), "lwp matches pid");
+static_assert (tid.matches (pid), "tid matches pid");
+static_assert (both.matches (pid), "both matches pid");
+static_assert (!ptid_t (2, 0, 0).matches (pid), "other pid doesn't match pid");
+static_assert (!ptid_t (2, 2, 0).matches (pid), "other lwp doesn't match pid");
+static_assert (!ptid_t (2, 0, 2).matches (pid), "other tid doesn't match pid");
+static_assert (!ptid_t (2, 2, 2).matches (pid), "other both doesn't match pid");
+
+/* Verify matches against exact matches.  */
+
+static_assert (!pid.matches (lwp), "pid matches lwp");
+static_assert (lwp.matches (lwp), "lwp matches lwp");
+static_assert (!tid.matches (lwp), "tid matches lwp");
+static_assert (!both.matches (lwp), "both matches lwp");
+static_assert (!ptid_t (2, 2, 0).matches (lwp), "other lwp doesn't match lwp");
+
+static_assert (!pid.matches (tid), "pid matches tid");
+static_assert (!lwp.matches (tid), "lwp matches tid");
+static_assert (tid.matches (tid), "tid matches tid");
+static_assert (!both.matches (tid), "both matches tid");
+static_assert (!ptid_t (2, 0, 2).matches (tid), "other tid doesn't match tid");
+
+static_assert (!pid.matches (both), "pid matches both");
+static_assert (!lwp.matches (both), "lwp matches both");
+static_assert (!tid.matches (both), "tid matches both");
+static_assert (both.matches (both), "both matches both");
+static_assert (!ptid_t (2, 2, 2).matches (both),
+	       "other both doesn't match both");
+
+
+} /* namespace ptid */
+} /* namespace selftests */