[1/4] gdb/python: have UnwindInfo.add_saved_register accept named args

diff --git a/gdb/doc/python.texi b/gdb/doc/python.texi
index c74d586ef39..ef50e6dbe7b 100644
--- a/gdb/doc/python.texi
+++ b/gdb/doc/python.texi
@@ -2882,8 +2882,8 @@ 
 create a @code{gdb.UnwindInfo} instance.  Use the following method to
 specify caller registers that have been saved in this frame:
 
-@defun gdb.UnwindInfo.add_saved_register (reg, value)
-@var{reg} identifies the register, for a description of the acceptable
+@defun gdb.UnwindInfo.add_saved_register (@var{register}, @var{value})
+@var{register} identifies the register, for a description of the acceptable
 values see @ref{gdbpy_frame_read_register,,Frame.read_register}.
 @var{value} is a register value (a @code{gdb.Value} object).
 @end defun
diff --git a/gdb/python/py-unwind.c b/gdb/python/py-unwind.c
index 409dbd3a470..2e13b84eb12 100644
--- a/gdb/python/py-unwind.c
+++ b/gdb/python/py-unwind.c
@@ -292,7 +292,7 @@  pyuw_create_unwind_info (PyObject *pyo_pending_frame,
    gdb.UnwindInfo.add_saved_register (REG, VALUE) -> None.  */
 
 static PyObject *
-unwind_infopy_add_saved_register (PyObject *self, PyObject *args)
+unwind_infopy_add_saved_register (PyObject *self, PyObject *args, PyObject *kw)
 {
   unwind_info_object *unwind_info = (unwind_info_object *) self;
   pending_frame_object *pending_frame
@@ -305,11 +305,15 @@  unwind_infopy_add_saved_register (PyObject *self, PyObject *args)
     {
       PyErr_SetString (PyExc_ValueError,
 		       "UnwindInfo instance refers to a stale PendingFrame");
-      return NULL;
+      return nullptr;
     }
-  if (!PyArg_UnpackTuple (args, "previous_frame_register", 2, 2,
-			  &pyo_reg_id, &pyo_reg_value))
-    return NULL;
+
+  static const char *keywords[] = { "register", "value", nullptr };
+  if (!gdb_PyArg_ParseTupleAndKeywords (args, kw, "OO!", keywords,
+					&pyo_reg_id, &value_object_type,
+					&pyo_reg_value))
+    return nullptr;
+
   if (!gdbpy_parse_register_id (pending_frame->gdbarch, pyo_reg_id, &regnum))
     return nullptr;
 
@@ -332,43 +336,38 @@  unwind_infopy_add_saved_register (PyObject *self, PyObject *args)
 	}
     }
 
-  {
-    struct value *value;
-    size_t data_size;
+  /* The argument parsing above guarantees that PYO_REG_VALUE will be a
+     gdb.Value object, as a result the value_object_to_value call should
+     succeed.  */
+  gdb_assert (pyo_reg_value != nullptr);
+  struct value *value = value_object_to_value (pyo_reg_value);
+  gdb_assert (value != nullptr);
+
+  ULONGEST reg_size = register_size (pending_frame->gdbarch, regnum);
+  if (reg_size != value->type ()->length ())
+    {
+      PyErr_Format (PyExc_ValueError,
+		    "The value of the register returned by the Python "
+		    "sniffer has unexpected size: %s instead of %s.",
+		    pulongest (value->type ()->length ()),
+		    pulongest (reg_size));
+      return nullptr;
+    }
+
+  gdbpy_ref<> new_value = gdbpy_ref<>::new_reference (pyo_reg_value);
+  bool found = false;
+  for (saved_reg &reg : *unwind_info->saved_regs)
+    {
+      if (regnum == reg.number)
+	{
+	  found = true;
+	  reg.value = std::move (new_value);
+	  break;
+	}
+    }
+  if (!found)
+    unwind_info->saved_regs->emplace_back (regnum, std::move (new_value));
 
-    if (pyo_reg_value == NULL
-      || (value = value_object_to_value (pyo_reg_value)) == NULL)
-      {
-	PyErr_SetString (PyExc_ValueError, "Bad register value");
-	return NULL;
-      }
-    data_size = register_size (pending_frame->gdbarch, regnum);
-    if (data_size != value->type ()->length ())
-      {
-	PyErr_Format (
-	    PyExc_ValueError,
-	    "The value of the register returned by the Python "
-	    "sniffer has unexpected size: %u instead of %u.",
-	    (unsigned) value->type ()->length (),
-	    (unsigned) data_size);
-	return NULL;
-      }
-  }
-  {
-    gdbpy_ref<> new_value = gdbpy_ref<>::new_reference (pyo_reg_value);
-    bool found = false;
-    for (saved_reg &reg : *unwind_info->saved_regs)
-      {
-	if (regnum == reg.number)
-	  {
-	    found = true;
-	    reg.value = std::move (new_value);
-	    break;
-	  }
-      }
-    if (!found)
-      unwind_info->saved_regs->emplace_back (regnum, std::move (new_value));
-  }
   Py_RETURN_NONE;
 }
 
@@ -1087,7 +1086,8 @@  PyTypeObject pending_frame_object_type =
 static PyMethodDef unwind_info_object_methods[] =
 {
   { "add_saved_register",
-    unwind_infopy_add_saved_register, METH_VARARGS,
+    (PyCFunction) unwind_infopy_add_saved_register,
+    METH_VARARGS | METH_KEYWORDS,
     "add_saved_register (REG, VALUE) -> None\n"
     "Set the value of the REG in the previous frame to VALUE." },
   { NULL }  /* Sentinel */
diff --git a/gdb/testsuite/gdb.python/py-unwind.exp b/gdb/testsuite/gdb.python/py-unwind.exp
index fddf4f15393..37c8fd8fbb1 100644
--- a/gdb/testsuite/gdb.python/py-unwind.exp
+++ b/gdb/testsuite/gdb.python/py-unwind.exp
@@ -131,10 +131,17 @@  gdb_test "disable unwinder global \"test unwinder\"" \
 check_for_broken_backtrace "stack is broken after command disabling"
 check_info_unwinder "info unwinder after command disabling" off
 
-# Check that invalid register names cause errors.
-gdb_test "python print(add_saved_register_error)" "True" \
-    "add_saved_register error"
-gdb_test "python print(read_register_error)" "True" \
+# Check that invalid register names and values cause errors.
+gdb_test "python print(add_saved_register_errors\[\"unknown_name\"\])" \
+    "Bad register" \
+    "add_saved_register error when an unknown register name is used"
+gdb_test "python print(add_saved_register_errors\[\"unknown_number\"\])" \
+    "Bad register" \
+    "add_saved_register error when an unknown register number is used"
+gdb_test "python print(add_saved_register_errors\[\"bad_value\"\])" \
+    "argument 2 must be gdb.Value, not int" \
+    "add_saved_register error when invalid register value is used"
+gdb_test "python print(read_register_error)" "Bad register" \
     "read_register error"
 
 # Try to create an unwinder object with a non-string name.
diff --git a/gdb/testsuite/gdb.python/py-unwind.py b/gdb/testsuite/gdb.python/py-unwind.py
index 4e110c51e3b..5853abc7486 100644
--- a/gdb/testsuite/gdb.python/py-unwind.py
+++ b/gdb/testsuite/gdb.python/py-unwind.py
@@ -18,7 +18,7 @@  from gdb.unwinder import Unwinder, FrameId
 
 
 # These are set to test whether invalid register names cause an error.
-add_saved_register_error = False
+add_saved_register_errors = {}
 read_register_error = False
 
 
@@ -94,9 +94,9 @@  class TestUnwinder(Unwinder):
 
             try:
                 pending_frame.read_register("nosuchregister")
-            except ValueError:
+            except ValueError as ve:
                 global read_register_error
-                read_register_error = True
+                read_register_error = str(ve)
 
             frame_id = FrameId(
                 pending_frame.read_register(TestUnwinder.AMD64_RSP),
@@ -104,13 +104,25 @@  class TestUnwinder(Unwinder):
             )
             unwind_info = pending_frame.create_unwind_info(frame_id)
             unwind_info.add_saved_register(TestUnwinder.AMD64_RBP, previous_bp)
-            unwind_info.add_saved_register("rip", previous_ip)
-            unwind_info.add_saved_register("rsp", previous_sp)
+            unwind_info.add_saved_register(value=previous_ip, register="rip")
+            unwind_info.add_saved_register(register="rsp", value=previous_sp)
+
+            global add_saved_register_errors
             try:
                 unwind_info.add_saved_register("nosuchregister", previous_sp)
-            except ValueError:
-                global add_saved_register_error
-                add_saved_register_error = True
+            except ValueError as ve:
+                add_saved_register_errors["unknown_name"] = str(ve)
+
+            try:
+                unwind_info.add_saved_register(999, previous_sp)
+            except ValueError as ve:
+                add_saved_register_errors["unknown_number"] = str(ve)
+
+            try:
+                unwind_info.add_saved_register("rsp", 1234)
+            except TypeError as ve:
+                add_saved_register_errors["bad_value"] = str(ve)
+
             return unwind_info
         except (gdb.error, RuntimeError):
             return None