[LLDB] Add a child property to compliment the existing parent property

[Jlalond]

I've been working on some scripts that evaluate the parent and child frame. It's been very annoying that the parent frame has a property but not the child. So I've added this to the extensions, I would've preferred to return None, but because the existing impl returns an invalid SBFrame, so I'm conforming to that API.

(lldb) script
Python Interactive Interpreter. To exit, type 'quit()', 'exit()' or Ctrl-D.
>>> lldb.frame
frame #0: 0x0000555555555200 fib.out`main
>>> lldb.frame.parent
frame #1: 0x00007ffff782a610 libc.so.6`__libc_start_call_main + 128
>>> lldb.frame.parent.child
frame #0: 0x0000555555555200 fib.out`main

[llvmbot]

@llvm/pr-subscribers-lldb

Author: Jacob Lalonde (Jlalond)

Changes

I've been working on some scripts that evaluate the parent and child frame. It's been very annoying that the parent frame has a property but not the child. So I've added this to the extensions, I would've preferred to return None, but because the existing impl returns an invalid SBFrame, so I'm conforming to that API.

(lldb) script
Python Interactive Interpreter. To exit, type 'quit()', 'exit()' or Ctrl-D.
>>> lldb.frame
frame #<!-- -->0: 0x0000555555555200 fib.out`main
&gt;&gt;&gt; lldb.frame.parent
frame #<!-- -->1: 0x00007ffff782a610 libc.so.6`__libc_start_call_main + 128
&gt;&gt;&gt; lldb.frame.parent.child
frame #<!-- -->0: 0x0000555555555200 fib.out`main

---

Full diff: https://github.com/llvm/llvm-project/pull/168619.diff

1 Files Affected:

• (modified) lldb/bindings/interface/SBFrameExtensions.i (+8)

diff --git a/lldb/bindings/interface/SBFrameExtensions.i b/lldb/bindings/interface/SBFrameExtensions.i
index 38d03abaee8f0..0c79b98b290f2 100644
--- a/lldb/bindings/interface/SBFrameExtensions.i
+++ b/lldb/bindings/interface/SBFrameExtensions.i
@@ -24,6 +24,13 @@ STRING_EXTENSION_OUTSIDE(SBFrame)
             else:
                 return SBFrame()
 
+        def get_child_frame(self):
+            child_idx = self.idx - 1
+            if child_idx >= 0:
+                return self.thread.frame[child_idx]
+            else:
+                return SBFrame()
+
         def get_arguments(self):
             return self.GetVariables(True,False,False,False)
 
@@ -92,6 +99,7 @@ STRING_EXTENSION_OUTSIDE(SBFrame)
         register = property(get_registers_access, None, doc='''A read only property that returns an helper object providing a flattened indexable view of the CPU registers for this stack frame.''')
         reg = property(get_registers_access, None, doc='''A read only property that returns an helper object providing a flattened indexable view of the CPU registers for this stack frame''')
         parent = property(get_parent_frame, None, doc='''A read only property that returns the parent (caller) frame of the current frame.''')
+        child = property(get_child_frame, None, doc='''A read only property that returns the child (callee) frame of the current frame.''')
     %}
 #endif
 }

[github-actions]

🐧 Linux x64 Test Results

• 33162 tests passed
• 495 tests skipped

[jimingham]

LGTM. Apparently we don't test that these property affordances at all, so far as I can see. We really should do that, but given nobody else has it seems unfair to require it for this patch...

[Jlalond]

LGTM. Apparently we don't test that these property affordances at all, so far as I can see. We really should do that, but given nobody else has it seems unfair to require it for this patch...

Opened an issue #168920, end of the year will be very busy for me personally but I will also look into adding more tests in the future!