clean up some target delegation cases

This patch cleans up some minor inconsistencies in target delegation.
It's primary purpose is to avoid confusion in the code.  A few spots
were checking the "beneath" target; however this can only be NULL for
the dummy target, so such tests are not needed.  Some other spots were
iterating over the beneath targets, looking for a method
implementation.  This is not needed for methods handled by
make-target-delegates, as there is always an implementation.

2014-07-18  Tom Tromey  <tromey@redhat.com>

	PR gdb/17130:
	* spu-multiarch.c (spu_region_ok_for_hw_watchpoint)
	(spu_fetch_registers, spu_store_registers, spu_xfer_partial)
	(spu_search_memory, spu_mourn_inferior): Simplify delegation.
	* linux-thread-db.c (thread_db_pid_to_str): Always delegate.
	* windows-nat.c (windows_xfer_partial): Always delegate.
	* record-btrace.c (record_btrace_xfer_partial): Simplify
	delegation.
	(record_btrace_fetch_registers, record_btrace_store_registers)
	(record_btrace_prepare_to_store, record_btrace_resume)
	(record_btrace_wait, record_btrace_find_new_threads)
	(record_btrace_thread_alive): Likewise.
	* procfs.c (procfs_xfer_partial): Always delegate.
	* corelow.c (core_xfer_partial): Always delegate.
	* sol-thread.c (sol_find_new_threads): Simplify delegation.

8 files changed, 50 insertions, 97 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 7b09eed..ffecd79 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,23 @@
 2014-07-18  Tom Tromey  <tromey@redhat.com>
 
+	PR gdb/17130:
+	* spu-multiarch.c (spu_region_ok_for_hw_watchpoint)
+	(spu_fetch_registers, spu_store_registers, spu_xfer_partial)
+	(spu_search_memory, spu_mourn_inferior): Simplify delegation.
+	* linux-thread-db.c (thread_db_pid_to_str): Always delegate.
+	* windows-nat.c (windows_xfer_partial): Always delegate.
+	* record-btrace.c (record_btrace_xfer_partial): Simplify
+	delegation.
+	(record_btrace_fetch_registers, record_btrace_store_registers)
+	(record_btrace_prepare_to_store, record_btrace_resume)
+	(record_btrace_wait, record_btrace_find_new_threads)
+	(record_btrace_thread_alive): Likewise.
+	* procfs.c (procfs_xfer_partial): Always delegate.
+	* corelow.c (core_xfer_partial): Always delegate.
+	* sol-thread.c (sol_find_new_threads): Simplify delegation.
+
+2014-07-18  Tom Tromey  <tromey@redhat.com>
+
 	* exec.c (exec_make_note_section): Move earlier.
 
 2014-07-17  Doug Evans  <dje@google.com>
diff --git a/gdb/corelow.c b/gdb/corelow.c
index 1775a66..0a066f4 100644
--- a/gdb/corelow.c
+++ b/gdb/corelow.c
@@ -871,12 +871,10 @@ core_xfer_partial (struct target_ops *ops, enum target_object object,
       return TARGET_XFER_E_IO;
 
     default:
-      if (ops->beneath != NULL)
-	return ops->beneath->to_xfer_partial (ops->beneath, object,
-					      annex, readbuf,
-					      writebuf, offset, len,
-					      xfered_len);
-      return TARGET_XFER_E_IO;
+      return ops->beneath->to_xfer_partial (ops->beneath, object,
+					    annex, readbuf,
+					    writebuf, offset, len,
+					    xfered_len);
     }
 }
 
diff --git a/gdb/linux-thread-db.c b/gdb/linux-thread-db.c
index 15902d8..af8232a 100644
--- a/gdb/linux-thread-db.c
+++ b/gdb/linux-thread-db.c
@@ -1767,10 +1767,7 @@ thread_db_pid_to_str (struct target_ops *ops, ptid_t ptid)
     }
 
   beneath = find_target_beneath (ops);
-  if (beneath->to_pid_to_str (beneath, ptid))
-    return beneath->to_pid_to_str (beneath, ptid);
-
-  return normal_pid_to_str (ptid);
+  return beneath->to_pid_to_str (beneath, ptid);
 }
 
 /* Return a string describing the state of the thread specified by
diff --git a/gdb/procfs.c b/gdb/procfs.c
index 4caaf7b..5075dcd 100644
--- a/gdb/procfs.c
+++ b/gdb/procfs.c
@@ -3993,11 +3993,9 @@ procfs_xfer_partial (struct target_ops *ops, enum target_object object,
 #endif
 
     default:
-      if (ops->beneath != NULL)
-	return ops->beneath->to_xfer_partial (ops->beneath, object, annex,
-					      readbuf, writebuf, offset, len,
-					      xfered_len);
-      return TARGET_XFER_E_IO;
+      return ops->beneath->to_xfer_partial (ops->beneath, object, annex,
+					    readbuf, writebuf, offset, len,
+					    xfered_len);
     }
 }
 
diff --git a/gdb/record-btrace.c b/gdb/record-btrace.c
index 5ba4e06..e48ad61 100644
--- a/gdb/record-btrace.c
+++ b/gdb/record-btrace.c
@@ -896,13 +896,9 @@ record_btrace_xfer_partial (struct target_ops *ops, enum target_object object,
     }
 
   /* Forward the request.  */
-  for (ops = ops->beneath; ops != NULL; ops = ops->beneath)
-    if (ops->to_xfer_partial != NULL)
-      return ops->to_xfer_partial (ops, object, annex, readbuf, writebuf,
-				   offset, len, xfered_len);
-
-  *xfered_len = len;
-  return TARGET_XFER_UNAVAILABLE;
+  ops = ops->beneath;
+  return ops->to_xfer_partial (ops, object, annex, readbuf, writebuf,
+			       offset, len, xfered_len);
 }
 
 /* The to_insert_breakpoint method of target record-btrace.  */
@@ -996,14 +992,9 @@ record_btrace_fetch_registers (struct target_ops *ops,
     }
   else
     {
-      struct target_ops *t;
+      struct target_ops *t = ops->beneath;
 
-      for (t = ops->beneath; t != NULL; t = t->beneath)
-	if (t->to_fetch_registers != NULL)
-	  {
-	    t->to_fetch_registers (t, regcache, regno);
-	    break;
-	  }
+      t->to_fetch_registers (t, regcache, regno);
     }
 }
 
@@ -1020,14 +1011,8 @@ record_btrace_store_registers (struct target_ops *ops,
 
   gdb_assert (may_write_registers != 0);
 
-  for (t = ops->beneath; t != NULL; t = t->beneath)
-    if (t->to_store_registers != NULL)
-      {
-	t->to_store_registers (t, regcache, regno);
-	return;
-      }
-
-  noprocess ();
+  t = ops->beneath;
+  t->to_store_registers (t, regcache, regno);
 }
 
 /* The to_prepare_to_store method of target record-btrace.  */
@@ -1041,12 +1026,8 @@ record_btrace_prepare_to_store (struct target_ops *ops,
   if (!record_btrace_generating_corefile && record_btrace_is_replaying (ops))
     return;
 
-  for (t = ops->beneath; t != NULL; t = t->beneath)
-    if (t->to_prepare_to_store != NULL)
-      {
-	t->to_prepare_to_store (t, regcache);
-	return;
-      }
+  t = ops->beneath;
+  t->to_prepare_to_store (t, regcache);
 }
 
 /* The branch trace frame cache.  */
@@ -1533,11 +1514,8 @@ record_btrace_resume (struct target_ops *ops, ptid_t ptid, int step,
   /* As long as we're not replaying, just forward the request.  */
   if (!record_btrace_is_replaying (ops) && execution_direction != EXEC_REVERSE)
     {
-      for (ops = ops->beneath; ops != NULL; ops = ops->beneath)
-	if (ops->to_resume != NULL)
-	  return ops->to_resume (ops, ptid, step, signal);
-
-      error (_("Cannot find target for stepping."));
+      ops = ops->beneath;
+      return ops->to_resume (ops, ptid, step, signal);
     }
 
   /* Compute the btrace thread flag for the requested move.  */
@@ -1760,11 +1738,8 @@ record_btrace_wait (struct target_ops *ops, ptid_t ptid,
   /* As long as we're not replaying, just forward the request.  */
   if (!record_btrace_is_replaying (ops) && execution_direction != EXEC_REVERSE)
     {
-      for (ops = ops->beneath; ops != NULL; ops = ops->beneath)
-	if (ops->to_wait != NULL)
-	  return ops->to_wait (ops, ptid, status, options);
-
-      error (_("Cannot find target for waiting."));
+      ops = ops->beneath;
+      return ops->to_wait (ops, ptid, status, options);
     }
 
   /* Let's find a thread to move.  */
@@ -1826,12 +1801,8 @@ record_btrace_find_new_threads (struct target_ops *ops)
     return;
 
   /* Forward the request.  */
-  for (ops = ops->beneath; ops != NULL; ops = ops->beneath)
-    if (ops->to_find_new_threads != NULL)
-      {
-	ops->to_find_new_threads (ops);
-	break;
-      }
+  ops = ops->beneath;
+  ops->to_find_new_threads (ops);
 }
 
 /* The to_thread_alive method of target record-btrace.  */
@@ -1844,11 +1815,8 @@ record_btrace_thread_alive (struct target_ops *ops, ptid_t ptid)
     return find_thread_ptid (ptid) != NULL;
 
   /* Forward the request.  */
-  for (ops = ops->beneath; ops != NULL; ops = ops->beneath)
-    if (ops->to_thread_alive != NULL)
-      return ops->to_thread_alive (ops, ptid);
-
-  return 0;
+  ops = ops->beneath;
+  return ops->to_thread_alive (ops, ptid);
 }
 
 /* Set the replay branch trace instruction iterator.  If IT is NULL, replay
diff --git a/gdb/sol-thread.c b/gdb/sol-thread.c
index 81a6915..38ca2f6 100644
--- a/gdb/sol-thread.c
+++ b/gdb/sol-thread.c
@@ -1084,8 +1084,7 @@ sol_find_new_threads (struct target_ops *ops)
   struct target_ops *beneath = find_target_beneath (ops);
 
   /* First Find any new LWP's.  */
-  if (beneath->to_find_new_threads != NULL)
-    beneath->to_find_new_threads (beneath);
+  beneath->to_find_new_threads (beneath);
 
   /* Then find any new user-level threads.  */
   p_td_ta_thr_iter (main_ta, sol_find_new_threads_callback, (void *) 0,
diff --git a/gdb/spu-multiarch.c b/gdb/spu-multiarch.c
index bd6c836..a22cc1b 100644
--- a/gdb/spu-multiarch.c
+++ b/gdb/spu-multiarch.c
@@ -122,18 +122,12 @@ spu_region_ok_for_hw_watchpoint (struct target_ops *self,
 				 CORE_ADDR addr, int len)
 {
   struct target_ops *ops_beneath = find_target_beneath (&spu_ops);
-  while (ops_beneath && !ops_beneath->to_region_ok_for_hw_watchpoint)
-    ops_beneath = find_target_beneath (ops_beneath);
 
   /* We cannot watch SPU local store.  */
   if (SPUADDR_SPU (addr) != -1)
     return 0;
 
-  if (ops_beneath)
-    return ops_beneath->to_region_ok_for_hw_watchpoint (ops_beneath,
-							addr, len);
-
-  return 0;
+  return ops_beneath->to_region_ok_for_hw_watchpoint (ops_beneath, addr, len);
 }
 
 /* Override the to_fetch_registers routine.  */
@@ -150,10 +144,6 @@ spu_fetch_registers (struct target_ops *ops,
   /* This version applies only if we're currently in spu_run.  */
   if (gdbarch_bfd_arch_info (gdbarch)->arch != bfd_arch_spu)
     {
-      while (ops_beneath && !ops_beneath->to_fetch_registers)
-	ops_beneath = find_target_beneath (ops_beneath);
-
-      gdb_assert (ops_beneath);
       ops_beneath->to_fetch_registers (ops_beneath, regcache, regno);
       return;
     }
@@ -208,10 +198,6 @@ spu_store_registers (struct target_ops *ops,
   /* This version applies only if we're currently in spu_run.  */
   if (gdbarch_bfd_arch_info (gdbarch)->arch != bfd_arch_spu)
     {
-      while (ops_beneath && !ops_beneath->to_fetch_registers)
-	ops_beneath = find_target_beneath (ops_beneath);
-
-      gdb_assert (ops_beneath);
       ops_beneath->to_store_registers (ops_beneath, regcache, regno);
       return;
     }
@@ -254,9 +240,6 @@ spu_xfer_partial (struct target_ops *ops, enum target_object object,
 		  ULONGEST *xfered_len)
 {
   struct target_ops *ops_beneath = find_target_beneath (ops);
-  while (ops_beneath && !ops_beneath->to_xfer_partial)
-    ops_beneath = find_target_beneath (ops_beneath);
-  gdb_assert (ops_beneath);
 
   /* Use the "mem" spufs file to access SPU local store.  */
   if (object == TARGET_OBJECT_MEMORY)
@@ -308,12 +291,9 @@ spu_search_memory (struct target_ops* ops,
 		   CORE_ADDR *found_addrp)
 {
   struct target_ops *ops_beneath = find_target_beneath (ops);
-  while (ops_beneath && !ops_beneath->to_search_memory)
-    ops_beneath = find_target_beneath (ops_beneath);
 
-  /* For SPU local store, always fall back to the simple method.  Likewise
-     if we do not have any target-specific special implementation.  */
-  if (!ops_beneath || SPUADDR_SPU (start_addr) >= 0)
+  /* For SPU local store, always fall back to the simple method.  */
+  if (SPUADDR_SPU (start_addr) >= 0)
     return simple_search_memory (ops,
 				 start_addr, search_space_len,
 				 pattern, pattern_len, found_addrp);
@@ -378,10 +358,7 @@ static void
 spu_mourn_inferior (struct target_ops *ops)
 {
   struct target_ops *ops_beneath = find_target_beneath (ops);
-  while (ops_beneath && !ops_beneath->to_mourn_inferior)
-    ops_beneath = find_target_beneath (ops_beneath);
 
-  gdb_assert (ops_beneath);
   ops_beneath->to_mourn_inferior (ops_beneath);
   spu_multiarch_deactivate ();
 }
diff --git a/gdb/windows-nat.c b/gdb/windows-nat.c
index e912fa4..74fe30f 100644
--- a/gdb/windows-nat.c
+++ b/gdb/windows-nat.c
@@ -2519,11 +2519,9 @@ windows_xfer_partial (struct target_ops *ops, enum target_object object,
 					    writebuf, offset, len, xfered_len);
 
     default:
-      if (ops->beneath != NULL)
-	return ops->beneath->to_xfer_partial (ops->beneath, object, annex,
-					      readbuf, writebuf, offset, len,
-					      xfered_len);
-      return TARGET_XFER_E_IO;
+      return ops->beneath->to_xfer_partial (ops->beneath, object, annex,
+					    readbuf, writebuf, offset, len,
+					    xfered_len);
     }
 }