bpo-45256: Remove the usage of the C stack in Python to Python calls (GH-28488)

Ths commit inlines calls to Python functions in the eval loop and steals all the arguments in the call from the caller for
performance.

Tools/gdb/libpython.py

@@ -45,6 +45,7 @@ The module also extends gdb with some python-specific commands.
 # compatible (2.6+ and 3.0+).  See #19308.
 
 from __future__ import print_function
+
 import gdb
 import os
 import locale
@@ -991,6 +992,11 @@ class PyFramePtr:
     def _f_lasti(self):
         return self._f_special("f_lasti", int_from_int)
 
+    def depth(self):
+        return self._f_special("depth", int_from_int)
+
+    def previous(self):
+        return self._f_special("previous", PyFramePtr)
 
     def iter_globals(self):
         '''
@@ -1797,16 +1803,20 @@ class Frame(object):
 
     def print_summary(self):
         if self.is_evalframe():
-            pyop = self.get_pyop()
-            if pyop:
-                line = pyop.get_truncated_repr(MAX_OUTPUT_LEN)
-                write_unicode(sys.stdout, '#%i %s\n' % (self.get_index(), line))
-                if not pyop.is_optimized_out():
-                    line = pyop.current_line()
-                    if line is not None:
-                        sys.stdout.write('    %s\n' % line.strip())
-            else:
-                sys.stdout.write('#%i (unable to read python frame information)\n' % self.get_index())
+            interp_frame = self.get_pyop()
+            while True:
+                if interp_frame:
+                    line = interp_frame.get_truncated_repr(MAX_OUTPUT_LEN)
+                    write_unicode(sys.stdout, '#%i %s\n' % (self.get_index(), line))
+                    if not interp_frame.is_optimized_out():
+                        line = interp_frame.current_line()
+                        if line is not None:
+                            sys.stdout.write('    %s\n' % line.strip())
+                    if interp_frame.depth() == 0:
+                        break
+                else:
+                    sys.stdout.write('#%i (unable to read python frame information)\n' % self.get_index())
+                interp_frame = interp_frame.previous()
         else:
             info = self.is_other_python_frame()
             if info:
@@ -1816,15 +1826,19 @@ class Frame(object):
 
     def print_traceback(self):
         if self.is_evalframe():
-            pyop = self.get_pyop()
-            if pyop:
-                pyop.print_traceback()
-                if not pyop.is_optimized_out():
-                    line = pyop.current_line()
-                    if line is not None:
-                        sys.stdout.write('    %s\n' % line.strip())
-            else:
-                sys.stdout.write('  (unable to read python frame information)\n')
+            interp_frame = self.get_pyop()
+            while True:
+                if interp_frame:
+                    interp_frame.print_traceback()
+                    if not interp_frame.is_optimized_out():
+                        line = interp_frame.current_line()
+                        if line is not None:
+                            sys.stdout.write('    %s\n' % line.strip())
+                    if interp_frame.depth() == 0:
+                        break
+                else:
+                    sys.stdout.write('  (unable to read python frame information)\n')
+                interp_frame = interp_frame.previous()
         else:
             info = self.is_other_python_frame()
             if info:
@@ -1914,11 +1928,15 @@ PyList()
 
 def move_in_stack(move_up):
     '''Move up or down the stack (for the py-up/py-down command)'''
+    # Important:
+    # The amount of frames that are printed out depends on how many frames are inlined
+    # in the same evaluation loop. As this command links directly the C stack with the
+    # Python stack, the results are sensitive to the number of inlined frames and this
+    # is likely to change between versions and optimizations.
     frame = Frame.get_selected_python_frame()
     if not frame:
         print('Unable to locate python frame')
         return
-
     while frame:
         if move_up:
             iter_frame = frame.older()
@@ -1940,9 +1958,10 @@ def move_in_stack(move_up):
         print('Unable to find an older python frame')
     else:
         print('Unable to find a newer python frame')
+    
 
 class PyUp(gdb.Command):
-    'Select and print the python stack frame that called this one (if any)'
+    'Select and print all python stack frame in the same eval loop starting from the one that called this one (if any)'
     def __init__(self):
         gdb.Command.__init__ (self,
                               "py-up",
@@ -1954,7 +1973,7 @@ class PyUp(gdb.Command):
         move_in_stack(move_up=True)
 
 class PyDown(gdb.Command):
-    'Select and print the python stack frame called by this one (if any)'
+    'Select and print all python stack frame in the same eval loop starting from the one called this one (if any)'
     def __init__(self):
         gdb.Command.__init__ (self,
                               "py-down",
@@ -2067,13 +2086,20 @@ class PyLocals(gdb.Command):
             return
 
         pyop_frame = frame.get_pyop()
-        if not pyop_frame:
-            print(UNABLE_READ_INFO_PYTHON_FRAME)
-            return
+        while True:
+            if not pyop_frame:
+                print(UNABLE_READ_INFO_PYTHON_FRAME)
 
-        for pyop_name, pyop_value in pyop_frame.iter_locals():
-            print('%s = %s'
-                   % (pyop_name.proxyval(set()),
-                      pyop_value.get_truncated_repr(MAX_OUTPUT_LEN)))
+            sys.stdout.write('Locals for %s\n' % (pyop_frame.co_name.proxyval(set())))
+
+            for pyop_name, pyop_value in pyop_frame.iter_locals():
+                print('%s = %s'
+                    % (pyop_name.proxyval(set()),
+                        pyop_value.get_truncated_repr(MAX_OUTPUT_LEN)))
+
+            if pyop_frame.depth() == 0:
+                break
+
+            pyop_frame = pyop_frame.previous()
 
 PyLocals()