[lldb] Introduce ScriptedFrame affordance (#149622)

This patch introduces a new scripting affordance in lldb:
`ScriptedFrame`.

This allows user to produce mock stackframes in scripted threads and
scripted processes from a python script.

With this change, StackFrame can be synthetized from different sources:
- Either from a dictionary containing a load address, and a frame index,
  which is the legacy way.
- Or by creating a ScriptedFrame python object.

One particularity of synthezising stackframes from the ScriptedFrame
python object, is that these frame have an optional PC, meaning that
they don't have a report a valid PC and they can act as shells that just
contain static information, like the frame function name, the list of
variables or registers, etc. It can also provide a symbol context.

rdar://157260006

Signed-off-by: Med Ismail Bennani <ismail@bennani.ma>

Signed-off-by: Med Ismail Bennani <ismail@bennani.ma>

1 files changed, 64 insertions, 1 deletions

diff --git a/lldb/test/API/functionalities/scripted_process/dummy_scripted_process.py b/lldb/test/API/functionalities/scripted_process/dummy_scripted_process.py
index 2721d961bcb9..835267221ddb 100644
--- a/lldb/test/API/functionalities/scripted_process/dummy_scripted_process.py
+++ b/lldb/test/API/functionalities/scripted_process/dummy_scripted_process.py
@@ -5,6 +5,7 @@ from typing import Any, Dict
 import lldb
 from lldb.plugins.scripted_process import ScriptedProcess
 from lldb.plugins.scripted_process import ScriptedThread
+from lldb.plugins.scripted_process import ScriptedFrame
 
 
 class DummyStopHook:
@@ -22,7 +23,7 @@ class DummyScriptedProcess(ScriptedProcess):
 
     def __init__(self, exe_ctx: lldb.SBExecutionContext, args: lldb.SBStructuredData):
         super().__init__(exe_ctx, args)
-        self.threads[0] = DummyScriptedThread(self, None)
+        self.threads[0] = DummyScriptedThread(self, args)
         self.memory = {}
         addr = 0x500000000
         debugger = self.target.GetDebugger()
@@ -69,6 +70,9 @@ class DummyScriptedThread(ScriptedThread):
     def __init__(self, process, args):
         super().__init__(process, args)
         self.frames.append({"pc": 0x0100001B00})
+        self.frames.append(DummyScriptedFrame(self, args, len(self.frames), "baz123"))
+        self.frames.append(DummyScriptedFrame(self, args, len(self.frames), "bar"))
+        self.frames.append(DummyScriptedFrame(self, args, len(self.frames), "foo"))
 
     def get_thread_id(self) -> int:
         return 0x19
@@ -109,6 +113,65 @@ class DummyScriptedThread(ScriptedThread):
         )
 
 
+class DummyScriptedFrame(ScriptedFrame):
+    def __init__(self, thread, args, id, name, sym_ctx=None):
+        super().__init__(thread, args)
+        self.id = id
+        self.name = name
+        self.sym_ctx = sym_ctx
+
+    def get_id(self):
+        return self.id
+
+    def get_function_name(self):
+        return self.name
+
+    def get_register_context(self) -> str:
+        return struct.pack(
+            "21Q",
+            0x10001,
+            0x10002,
+            0x10003,
+            0x10004,
+            0x10005,
+            0x10006,
+            0x10007,
+            0x10008,
+            0x10009,
+            0x100010,
+            0x100011,
+            0x100012,
+            0x100013,
+            0x100014,
+            0x100015,
+            0x100016,
+            0x100017,
+            0x100018,
+            0x100019,
+            0x100020,
+            0x100021,
+        )
+
+    def get_symbol_context(self):
+        def get_symbol_context_for_function(func_name):
+            module = self.target.FindModule(self.target.GetExecutable())
+            if not module.IsValid():
+                return None
+
+            sym_ctx_list = module.FindFunctions(func_name)
+            if not sym_ctx_list.IsValid() or sym_ctx_list.GetSize() == 0:
+                return None
+
+            return sym_ctx_list.GetContextAtIndex(0)
+
+        return (
+            self.sym_ctx if self.sym_ctx else get_symbol_context_for_function(self.name)
+        )
+
+    def get_scripted_frame_plugin(self):
+        return DummyScriptedFrame.__module__ + "." + DummyScriptedFrame.__name__
+
+
 def __lldb_init_module(debugger, dict):
     # This is used when loading the script in an interactive debug session to
     # automatically, register the stop-hook and launch the scripted process.