[Dexter] Adapt to upcoming lldb stepping behavior

cross-project-tests/debuginfo-tests/dexter/dex/debugger/lldb/LLDB.py

@@ -206,6 +206,33 @@ def launch(self, cmdline):
 
     def step(self):
         self._thread.StepInto()
+        stop_reason = self._thread.GetStopReason()
+        # If we (1) completed a step and (2) are sitting at a breakpoint,
+        # but (3) the breakpoint is not reported as the stop reason, then
+        # we'll need to step once more to hit the breakpoint.
+        #
+        # dexter sets breakpoints on every source line, then steps
+        # each source line. Older lldb's would overwrite the stop
+        # reason with "breakpoint hit" when we stopped at a breakpoint,
+        # even if the breakpoint hadn't been exectued yet.  One
+        # step per source line, hitting a breakpoint each time.
+        #
+        # But a more accurate behavior is that the step completes
+        # with step-completed stop reason, then when we step again,
+        # we execute the breakpoint and stop (with the pc the same) and
+        # a breakpoint-hit stop reason.  So we need to step twice per line.
+        if stop_reason == self._interface.eStopReasonPlanComplete:
+            stepped_to_breakpoint = False
+            pc = self._thread.GetFrameAtIndex(0).GetPC()
+            for bp in self._target.breakpoints:
+                for bploc in bp.locations:
+                    if (
+                        bploc.IsEnabled()
+                        and bploc.GetAddress().GetLoadAddress(self._target) == pc
+                    ):
+                        stepped_to_breakpoint = True
+            if stepped_to_breakpoint:
+                self._thread.StepInto()
 
     def go(self) -> ReturnCode:
         self._process.Continue()