Remove get_thread_id

This patch removes get_thread_id from aarch64-linux-nat.c,
arm-linux-nat.c and xtensa-linux-nat.c.

get_thread_id was added in this commit below in 2000,

  41c49b06c471443d3baf2eaa2463a315f9b5edca
  https://sourceware.org/ml/gdb-patches/2000-04/msg00398.html

which predates the ptid_t stuff added into GDB.  Nowadays, lwpid of
inferior_ptid is only zero when the inferior is created (in
fork-child.c:fork_inferior) and its lwpid will be set after
linux_nat_wait_1 gets the first event.  After that, lwpid of
inferior_ptid is not zero for linux-nat target, then we can use
ptid_get_lwp, so this function isn't needed anymore.

Even when GDB attaches to a process, the lwp of inferior_ptid
isn't zero,  see linux-nat.c:linux_nat_attach,

  /* The ptrace base target adds the main thread with (pid,0,0)
     format.  Decorate it with lwp info.  */
  ptid = ptid_build (ptid_get_pid (inferior_ptid),
		     ptid_get_pid (inferior_ptid),
		     0);

Note that linux_nat_xfer_partial shifts lwpid to pid for inferior_ptid
temperately for calling linux_ops->to_xfer_partial, but all the
affected functions in this patch are not called in
linux_ops->to_xfer_partial.

I think we can safely remove get_thread_id for all linux native targets.

Regression tested on arm-linux and aarch64-linux.  Unable to build
native GDB and test it on xtensa-linux.

gdb:

2015-08-05  Yao Qi  <yao.qi@linaro.org>

	* aarch64-linux-nat.c (get_thread_id): Remove.
	(debug_reg_change_callback): Call ptid_get_lwp instead of
	get_thread_id.
	(fetch_gregs_from_thread): Likewise.
	(store_gregs_to_thread): Likewise.
	(fetch_fpregs_from_thread): Likewise.
	(store_fpregs_to_thread): Likewise.
	(aarch64_linux_get_debug_reg_capacity): Likewise.
	* arm-linux-nat.c (get_thread_id): Remove.
	(GET_THREAD_ID): Update macro to use ptid_get_lwp.
	* xtensa-linux-nat.c (get_thread_id): Remove.
	(GET_THREAD_ID): Update macro to use ptid_get_lwp.
	* arm-linux-nat.c (get_thread_id): Remove.
	(GET_THREAD_ID): Remove.
	(fetch_fpregs): Call ptid_get_lwp instead of GET_THREAD_ID.
	(store_fpregs, fetch_regs, store_regs): Likewise.
	(fetch_wmmx_regs, store_wmmx_regs): Likewise.
	(fetch_vfp_regs, store_vfp_regs): Likewise.
	(arm_linux_read_description): Likewise.
	(arm_linux_get_hwbp_cap): Likewise.
	* xtensa-linux-nat.c (get_thread_id): Remove.
	(GET_THREAD_ID): Remove.
	(fetch_gregs, store_gregs): Call ptid_get_lwp instead of
	GET_THREAD_ID.

1 files changed, 5 insertions, 21 deletions

diff --git a/gdb/aarch64-linux-nat.c b/gdb/aarch64-linux-nat.c
index b6ee502..e7bae10 100644
--- a/gdb/aarch64-linux-nat.c
+++ b/gdb/aarch64-linux-nat.c
@@ -48,22 +48,6 @@
 #define TRAP_HWBKPT 0x0004
 #endif
 
-/* On GNU/Linux, threads are implemented as pseudo-processes, in which
-   case we may be tracing more than one process at a time.  In that
-   case, inferior_ptid will contain the main process ID and the
-   individual thread (process) ID.  get_thread_id () is used to get
-   the thread id if it's available, and the process id otherwise.  */
-
-static int
-get_thread_id (ptid_t ptid)
-{
-  int tid = ptid_get_lwp (ptid);
-
-  if (0 == tid)
-    tid = ptid_get_pid (ptid);
-  return tid;
-}
-
 /* Per-process data.  We don't bind this to a per-inferior registry
    because of targets like x86 GNU/Linux that need to keep track of
    processes that aren't bound to any inferior (e.g., fork children,
@@ -181,7 +165,7 @@ debug_reg_change_callback (struct lwp_info *lwp, void *ptr)
 {
   struct aarch64_dr_update_callback_param *param_p
     = (struct aarch64_dr_update_callback_param *) ptr;
-  int pid = get_thread_id (lwp->ptid);
+  int pid = ptid_get_lwp (lwp->ptid);
   int idx = param_p->idx;
   int is_watchpoint = param_p->is_watchpoint;
   struct arch_lwp_info *info = lwp->arch_private;
@@ -266,7 +250,7 @@ fetch_gregs_from_thread (struct regcache *regcache)
      and arm.  */
   gdb_static_assert (sizeof (regs) >= 18 * 4);
 
-  tid = get_thread_id (inferior_ptid);
+  tid = ptid_get_lwp (inferior_ptid);
 
   iovec.iov_base = &regs;
   if (gdbarch_bfd_arch_info (gdbarch)->bits_per_word == 32)
@@ -303,7 +287,7 @@ store_gregs_to_thread (const struct regcache *regcache)
   /* Make sure REGS can hold all registers contents on both aarch64
      and arm.  */
   gdb_static_assert (sizeof (regs) >= 18 * 4);
-  tid = get_thread_id (inferior_ptid);
+  tid = ptid_get_lwp (inferior_ptid);
 
   iovec.iov_base = &regs;
   if (gdbarch_bfd_arch_info (gdbarch)->bits_per_word == 32)
@@ -347,7 +331,7 @@ fetch_fpregs_from_thread (struct regcache *regcache)
      and arm.  */
   gdb_static_assert (sizeof regs >= VFP_REGS_SIZE);
 
-  tid = get_thread_id (inferior_ptid);
+  tid = ptid_get_lwp (inferior_ptid);
 
   iovec.iov_base = &regs;
 
@@ -394,7 +378,7 @@ store_fpregs_to_thread (const struct regcache *regcache)
   /* Make sure REGS can hold all VFP registers contents on both aarch64
      and arm.  */
   gdb_static_assert (sizeof regs >= VFP_REGS_SIZE);
-  tid = get_thread_id (inferior_ptid);
+  tid = ptid_get_lwp (inferior_ptid);
 
   iovec.iov_base = &regs;