Bug 959016 - Add lldb Python command handlers for debugging Gecko, starting with frametree and frametreelimited. (DONTBUILD) r=ehsan

.lldbinit

@@ -9,3 +9,8 @@ settings set target.inline-breakpoint-strategy always
 # will show a variable declared as "nsIFrame *" that points to an nsBlockFrame
 # object as being of type "nsBlockFrame *" rather than "nsIFrame *".
 settings set target.prefer-dynamic-value run-target
+
+# Import the module that defines complex Gecko debugging commands.  Rather
+# than do any kind of searching, this assumes that you are running lldb from
+# the top level source directory.
+script sys.path.append('python/lldbutils'); import lldbutils; lldbutils.init()

layout/generic/nsFrame.cpp

@@ -5374,6 +5374,12 @@ nsIFrame::DumpFrameTree()
   RootFrameList(PresContext(), stdout, 0);
 }
 
+void
+nsIFrame::DumpFrameTreeLimited()
+{
+  List(stdout, 0);
+}
+
 void
 nsIFrame::RootFrameList(nsPresContext* aPresContext, FILE* out, int32_t aIndent)
 {

layout/generic/nsIFrame.h

@@ -3261,6 +3261,7 @@ public:
   static void RootFrameList(nsPresContext* aPresContext,
                             FILE* out, int32_t aIndent);
   virtual void DumpFrameTree();
+  void DumpFrameTreeLimited();
 
   NS_IMETHOD  GetFrameName(nsAString& aResult) const = 0;
 #endif

python/lldbutils/README.txt

@@ -0,0 +1,12 @@
+lldb debugging functionality for Gecko
+--------------------------------------
+
+This directory contains a module, lldbutils, which is imported by the
+in-tree .lldbinit file.  The lldbutil modules define some lldb commands
+that are handy for debugging Gecko.
+
+If you want to add a new command or Python-implemented type summary, either add
+it to one of the existing broad area Python files (such as lldbutils/layout.py
+for layout-related commands) or create a new file if none of the existing files
+is appropriate.  If you add a new file, make sure you add it to __all__ in
+lldbutils/__init__.py.

python/lldbutils/lldbutils/__init__.py

@@ -0,0 +1,7 @@
+import lldb
+
+__all__ = ['layout']
+
+def init():
+    for name in __all__:
+        __import__('lldbutils.' + name, globals(), locals(), ['init']).init(lldb.debugger)

python/lldbutils/lldbutils/layout.py

@@ -0,0 +1,15 @@
+import lldb
+
+def frametree(debugger, command, result, dict):
+    """Dumps the frame tree containing the given nsIFrame*."""
+    debugger.HandleCommand('expr (' + command + ')->DumpFrameTree()')
+
+def frametreelimited(debugger, command, result, dict):
+    """Dumps the subtree of a frame tree rooted at the given nsIFrame*."""
+    debugger.HandleCommand('expr (' + command + ')->DumpFrameTreeLimited()')
+
+def init(debugger):
+    debugger.HandleCommand('command script add -f lldbutils.layout.frametree frametree')
+    debugger.HandleCommand('command script add -f lldbutils.layout.frametree frametreelimited')
+    debugger.HandleCommand('command alias ft frametree')
+    debugger.HandleCommand('command alias ftl frametree')