[RFC v5 11/18] gdb/python: allow instantiation of gdb.Symtab from Python

[Jan Vrany <jan.vrany@labware.com>]

This commit adds code to allow user extension to instantiate
gdb.Symtab. This is a step towards a Python support for dynamically
generated code (JIT) in GDB.

Reviewed-By: Eli Zaretskii <eliz@gnu.org>
---
 gdb/doc/python.texi                    |  4 ++
 gdb/python/py-symtab.c                 | 53 +++++++++++++++++++++++++-
 gdb/testsuite/gdb.python/py-symtab.exp | 14 +++++++
 3 files changed, 69 insertions(+), 2 deletions(-)

diff --git a/gdb/doc/python.texi b/gdb/doc/python.texi
index ffa78c0d859..65e243074ff 100644
--- a/gdb/doc/python.texi
+++ b/gdb/doc/python.texi
@@ -6650,6 +6650,10 @@ The @code{gdb.Compunit} this symbol table belongs to.
 
 A @code{gdb.Symtab} object has the following methods:
 
+@defun Symtab.__init__ (filename, compunit)
+Create a new symtab for given @var{filename} in given @var{compunit}.
+@end defun
+
 @defun Symtab.is_valid ()
 Returns @code{True} if the @code{gdb.Symtab} object is valid,
 @code{False} if not.  A @code{gdb.Symtab} object can become invalid if
diff --git a/gdb/python/py-symtab.c b/gdb/python/py-symtab.c
index 806a6efa4fd..2faeb963ea6 100644
--- a/gdb/python/py-symtab.c
+++ b/gdb/python/py-symtab.c
@@ -92,6 +92,8 @@ static const gdbpy_registry<gdbpy_tracking_registry_storage<sal_object,
 	}								\
   } while (0)
 
+static void set_symtab (symtab_object *obj, struct symtab *symtab);
+
 static PyObject *
 stpy_str (PyObject *self)
 {
@@ -235,6 +237,46 @@ stpy_get_linetable (PyObject *self, PyObject *args)
   return symtab_to_linetable_object (self);
 }
 
+/* Object initializer; creates new symtab.
+
+   Use: __init__(FILENAME, COMPUNIT).  */
+
+static int
+stpy_init (PyObject *zelf, PyObject *args, PyObject *kw)
+{
+  struct symtab_object *self = (struct symtab_object*) zelf;
+
+  if (self->symtab)
+    {
+      PyErr_Format (PyExc_RuntimeError,
+		    _("Symtab object already initialized."));
+      return -1;
+    }
+
+   static const char *keywords[] = { "filename", "compunit", nullptr };
+   const char *filename;
+   PyObject *cu_obj;
+
+   if (!gdb_PyArg_ParseTupleAndKeywords (args, kw, "sO", keywords,
+					 &filename, &cu_obj))
+    return -1;
+
+
+  compunit_symtab *cu = compunit_object_to_compunit (cu_obj);
+  if (cu == nullptr)
+    {
+      PyErr_Format (PyExc_TypeError,
+		    _("The compunit argument is not valid gdb.Compunit "
+		      "object"));
+      return -1;
+    }
+
+  struct symtab *symtab = allocate_symtab (cu, filename);
+  set_symtab (self, symtab);
+
+  return 0;
+}
+
 static PyObject *
 salpy_str (PyObject *self)
 {
@@ -438,7 +480,6 @@ symtab_object_to_symtab (PyObject *obj)
 static int CPYCHECKER_NEGATIVE_RESULT_SETS_EXCEPTION
 gdbpy_initialize_symtabs (void)
 {
-  symtab_object_type.tp_new = PyType_GenericNew;
   if (gdbpy_type_ready (&symtab_object_type) < 0)
     return -1;
 
@@ -514,7 +555,15 @@ PyTypeObject symtab_object_type = {
   0,				  /*tp_iternext */
   symtab_object_methods,	  /*tp_methods */
   0,				  /*tp_members */
-  symtab_object_getset		  /*tp_getset */
+  symtab_object_getset,		  /*tp_getset */
+  0,				  /*tp_base */
+  0,				  /*tp_dict */
+  0,				  /*tp_descr_get */
+  0,				  /*tp_descr_set */
+  0,                              /*tp_dictoffset */
+  stpy_init,	                  /*tp_init */
+  0,				  /*tp_alloc */
+  PyType_GenericNew,		  /*tp_new */
 };
 
 static gdb_PyGetSetDef sal_object_getset[] = {
diff --git a/gdb/testsuite/gdb.python/py-symtab.exp b/gdb/testsuite/gdb.python/py-symtab.exp
index 4828a0a33b6..fb1310da480 100644
--- a/gdb/testsuite/gdb.python/py-symtab.exp
+++ b/gdb/testsuite/gdb.python/py-symtab.exp
@@ -126,6 +126,16 @@ gdb_test "python print (symtab != \"xxx\")"\
     "True" \
     "test symtab non-equality with non-symtab"
 
+# Test creating new symtab in existing compunit
+gdb_py_test_silent_cmd "python cu = symtab.compunit" "remember compunit" 1
+gdb_test "python print(repr( gdb.Symtab(\"some_file.txt\", cu) ))" \
+    "<gdb.Symtab object at .*>" \
+    "test creation of symtab"
+
+gdb_test "python print(repr( gdb.Symtab(\"some_file.txt\", (1,2,3)) ))" \
+    "TypeError.*:.*" \
+    "test creation of symtab passing non-compunit object"
+
 # Test is_valid when the objfile is unloaded.  This must be the last
 # test as it unloads the object file in GDB.
 gdb_unload
@@ -136,3 +146,7 @@ gdb_test "python print (symtab.is_valid())" "False" \
 
 gdb_test_no_output "python sal = None" "test sal destructor"
 gdb_test_no_output "python symtab = None" "test symtab destructor"
+
+gdb_test "python print(repr( gdb.Symtab(\"some_file2.txt\", cu) ))" \
+    "TypeError.*:.*" \
+    "test creation of symtab passing invalid compunit"
-- 
2.47.2