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, 10 insertions, 27 deletions

diff --git a/gdb/arm-linux-nat.c b/gdb/arm-linux-nat.c
index 825da4c..fb65a5d 100644
--- a/gdb/arm-linux-nat.c
+++ b/gdb/arm-linux-nat.c
@@ -66,23 +66,6 @@
 
 extern int arm_apcs_32;
 
-/* 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;
-}
-
-#define GET_THREAD_ID(PTID)	get_thread_id (PTID)
-
 /* Get the whole floating point state of the process and store it
    into regcache.  */
 
@@ -93,7 +76,7 @@ fetch_fpregs (struct regcache *regcache)
   gdb_byte fp[ARM_LINUX_SIZEOF_NWFPE];
 
   /* Get the thread id for the ptrace call.  */
-  tid = GET_THREAD_ID (inferior_ptid);
+  tid = ptid_get_lwp (inferior_ptid);
 
   /* Read the floating point state.  */
   if (have_ptrace_getregset == TRIBOOL_TRUE)
@@ -133,7 +116,7 @@ store_fpregs (const struct regcache *regcache)
   gdb_byte fp[ARM_LINUX_SIZEOF_NWFPE];
 
   /* Get the thread id for the ptrace call.  */
-  tid = GET_THREAD_ID (inferior_ptid);
+  tid = ptid_get_lwp (inferior_ptid);
 
   /* Read the floating point state.  */
   if (have_ptrace_getregset == TRIBOOL_TRUE)
@@ -193,7 +176,7 @@ fetch_regs (struct regcache *regcache)
   elf_gregset_t regs;
 
   /* Get the thread id for the ptrace call.  */
-  tid = GET_THREAD_ID (inferior_ptid);
+  tid = ptid_get_lwp (inferior_ptid);
 
   if (have_ptrace_getregset == TRIBOOL_TRUE)
     {
@@ -223,7 +206,7 @@ store_regs (const struct regcache *regcache)
   elf_gregset_t regs;
 
   /* Get the thread id for the ptrace call.  */
-  tid = GET_THREAD_ID (inferior_ptid);
+  tid = ptid_get_lwp (inferior_ptid);
 
   /* Fetch the general registers.  */
   if (have_ptrace_getregset == TRIBOOL_TRUE)
@@ -277,7 +260,7 @@ fetch_wmmx_regs (struct regcache *regcache)
   int ret, regno, tid;
 
   /* Get the thread id for the ptrace call.  */
-  tid = GET_THREAD_ID (inferior_ptid);
+  tid = ptid_get_lwp (inferior_ptid);
 
   ret = ptrace (PTRACE_GETWMMXREGS, tid, 0, regbuf);
   if (ret < 0)
@@ -306,7 +289,7 @@ store_wmmx_regs (const struct regcache *regcache)
   int ret, regno, tid;
 
   /* Get the thread id for the ptrace call.  */
-  tid = GET_THREAD_ID (inferior_ptid);
+  tid = ptid_get_lwp (inferior_ptid);
 
   ret = ptrace (PTRACE_GETWMMXREGS, tid, 0, regbuf);
   if (ret < 0)
@@ -351,7 +334,7 @@ fetch_vfp_regs (struct regcache *regcache)
   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 
   /* Get the thread id for the ptrace call.  */
-  tid = GET_THREAD_ID (inferior_ptid);
+  tid = ptid_get_lwp (inferior_ptid);
 
   if (have_ptrace_getregset == TRIBOOL_TRUE)
     {
@@ -383,7 +366,7 @@ store_vfp_regs (const struct regcache *regcache)
   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 
   /* Get the thread id for the ptrace call.  */
-  tid = GET_THREAD_ID (inferior_ptid);
+  tid = ptid_get_lwp (inferior_ptid);
 
   if (have_ptrace_getregset == TRIBOOL_TRUE)
     {
@@ -553,7 +536,7 @@ arm_linux_read_description (struct target_ops *ops)
     {
       elf_gregset_t gpregs;
       struct iovec iov;
-      int tid = GET_THREAD_ID (inferior_ptid);
+      int tid = ptid_get_lwp (inferior_ptid);
 
       iov.iov_base = &gpregs;
       iov.iov_len = sizeof (gpregs);
@@ -636,7 +619,7 @@ arm_linux_get_hwbp_cap (void)
       int tid;
       unsigned int val;
 
-      tid = GET_THREAD_ID (inferior_ptid);
+      tid = ptid_get_lwp (inferior_ptid);
       if (ptrace (PTRACE_GETHBPREGS, tid, 0, &val) < 0)
 	available = 0;
       else