Re: [RFC - Python Scripting] Add 'end' attribute to gdb.Symtab_and_line

[Siva Chandra <sivachandra@google.com>]

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On Tue, Jun 12, 2012 at 2:52 AM, Doug Evans <dje@google.com> wrote:
> Let's go with "end_pc" and at least leave "pc" alone for now.

Done.

> One question we need to answer is what behaviour to expose in the API.
> Is the range [pc,end_pc] or [pc,end_pc)?
> [I know what the internal code does, but we don't have to follow it if
> it makes for a sufficiently better API.]

I have changed the behavior to [pc, end_pc] as this (at least the
name) feels more meaningful to me. But, why was right open behavior
chosen for internal code? Even the two-argument flavor of the
'disassemble' command has right open behavior.

> And we need to clearly document this behaviour.

I have described it in the documentation as "the end address of the
program counter address range for the current source line".

2012-06-12  Siva Chandra Reddy  <sivachandra@google.com>

        New attribute 'end_pc' for gdb.Symtab_and_line.
        * NEWS (Python Scripting): Add entry about the new attribute.
        * python/py-symtab.c (salpy_get_end_pc): New function which
        implements the get method for the 'end_pc' attribute of
        gdb.Symtab_and_line.
        (sal_object_getset): Add entry for the 'end_pc' attribute.

        doc/
        * gdb.texinfo (Symbol Tables In Python): Add description about
        the new 'end_pc' attribute of gdb.Symtab_and line.

        testsuite/
        * gdb.python/py-symtab.exp: Add tests to test the new attribute
        'end_pc' of gdb.Symtab_and_line.
        * gdb.python/py-symbol.c: Move break point comment to enable
        testing of gdb.Symtab_and_line.end_pc.

Thanks,
Siva Chandra

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Index: NEWS
===================================================================
RCS file: /cvs/src/src/gdb/NEWS,v
retrieving revision 1.527
diff -u -p -r1.527 NEWS
--- NEWS	6 Jun 2012 18:03:53 -0000	1.527
+++ NEWS	12 Jun 2012 18:28:02 -0000
@@ -60,6 +60,10 @@
   ** New function gdb.find_pc_line which returns the gdb.Symtab_and_line
      object associated with a PC value.
 
+  ** gdb.Symtab_and_line has new attribute 'end_pc' which holds the end
+     address of the program counter address range for the current source
+     line.
+
 * Go language support.
   GDB now supports debugging programs written in the Go programming
   language.
Index: doc/gdb.texinfo
===================================================================
RCS file: /cvs/src/src/gdb/doc/gdb.texinfo,v
retrieving revision 1.974
diff -u -p -r1.974 gdb.texinfo
--- doc/gdb.texinfo	8 Jun 2012 13:05:55 -0000	1.974
+++ doc/gdb.texinfo	12 Jun 2012 18:28:21 -0000
@@ -25262,6 +25262,11 @@ Indicates the current program counter ad
 writable.
 @end defvar
 
+@defvar Symtab_and_line.end_pc
+Indicates the end address of the program counter address range for
+the current source line.  This attribute is not writable.
+@end defvar
+
 @defvar Symtab_and_line.line
 Indicates the current line number for this object.  This
 attribute is not writable.
Index: python/py-symtab.c
===================================================================
RCS file: /cvs/src/src/gdb/python/py-symtab.c,v
retrieving revision 1.9
diff -u -p -r1.9 py-symtab.c
--- python/py-symtab.c	3 May 2012 07:07:25 -0000	1.9
+++ python/py-symtab.c	12 Jun 2012 18:28:22 -0000
@@ -237,6 +237,19 @@ salpy_get_pc (PyObject *self, void *clos
   return gdb_py_long_from_ulongest (sal->pc);
 }
 
+/* Implementation of the get method for the 'end_pc' attribute of
+   gdb.Symtab_and_line.  */
+
+static PyObject *
+salpy_get_end_pc (PyObject *self, void *closure)
+{
+  struct symtab_and_line *sal = NULL;
+
+  SALPY_REQUIRE_VALID (self, sal);
+
+  return gdb_py_long_from_ulongest (sal->end - 1);
+}
+
 static PyObject *
 salpy_get_line (PyObject *self, void *closure)
 {
@@ -556,6 +569,8 @@ static PyTypeObject symtab_object_type =
 static PyGetSetDef sal_object_getset[] = {
   { "symtab", salpy_get_symtab, NULL, "Symtab object.", NULL },
   { "pc", salpy_get_pc, NULL, "Return the symtab_and_line's pc.", NULL },
+  { "end_pc", salpy_get_end_pc, NULL,
+    "Return the symtab_and_line's end pc.", NULL },
   { "line", salpy_get_line, NULL,
     "Return the symtab_and_line's line.", NULL },
   {NULL}  /* Sentinel */
Index: testsuite/gdb.python/py-symbol.c
===================================================================
RCS file: /cvs/src/src/gdb/testsuite/gdb.python/py-symbol.c,v
retrieving revision 1.6
diff -u -p -r1.6 py-symbol.c
--- testsuite/gdb.python/py-symbol.c	3 May 2012 07:07:26 -0000	1.6
+++ testsuite/gdb.python/py-symbol.c	12 Jun 2012 18:28:23 -0000
@@ -40,8 +40,8 @@ int qq = 72;			/* line of qq */
 int func (int arg)
 {
   int i = 2;
-  i = i * arg;
-  return arg; /* Block break here.  */
+  i = i * arg; /* Block break here.  */
+  return arg;
 }
 
 struct simple_struct
Index: testsuite/gdb.python/py-symtab.exp
===================================================================
RCS file: /cvs/src/src/gdb/testsuite/gdb.python/py-symtab.exp,v
retrieving revision 1.9
diff -u -p -r1.9 py-symtab.exp
--- testsuite/gdb.python/py-symtab.exp	3 May 2012 07:07:26 -0000	1.9
+++ testsuite/gdb.python/py-symtab.exp	12 Jun 2012 18:28:23 -0000
@@ -54,10 +54,13 @@ gdb_py_test_silent_cmd "python static_bl
 gdb_py_test_silent_cmd "python global_symbols = \[\]; static_symbols = \[\]" "Set up symbol name lists" 0
 gdb_py_test_silent_cmd "python for sym in global_block: global_symbols.append(sym.name)" "Get global symbol names" 0
 gdb_py_test_silent_cmd "python for sym in static_block: static_symbols.append(sym.name)" "Get static symbol names" 0
+gdb_py_test_silent_cmd "step" "Step to the next line" 0
+gdb_py_test_silent_cmd "python new_pc = gdb.selected_frame().find_sal().pc" "Get new PC" 0
 
 # Test sal.
 gdb_test "python print sal.symtab" ".*gdb.python/py-symbol.c.*" "Test symtab"
 gdb_test "python print sal.pc" "${decimal}" "Test sal.pc"
+gdb_test "python print sal.end_pc == (new_pc - 1)" "True" "Test sal.end_pc"
 gdb_test "python print sal.line" "$line_no" "Test sal.line"
 gdb_test "python print sal.is_valid()" "True" "Test sal.is_valid"