Add more logging so I can figure out why TestBranchIslands.py is (llvm#139178)

failing but only on the bot.

Author: jimingham

lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderDarwin.cpp

@@ -1038,6 +1038,15 @@ DynamicLoaderDarwin::GetStepThroughTrampolinePlan(Thread &thread,
     static RegularExpression g_branch_island_regex(g_branch_island_pattern);
 
     bool is_branch_island = g_branch_island_regex.Execute(current_name);
+    // FIXME: this is extra logging so I can figure out why this test is failing
+    // on the bot but not locally with all the same tools, etc...
+    if (thread_plan_sp && is_branch_island) {
+      if (log) {
+        StreamString s;
+        thread_plan_sp->GetDescription(&s, eDescriptionLevelVerbose);
+        LLDB_LOGF(log, "Am at a branch island, but already had plan: \n\t%s", s.GetData());
+      }
+    }
     if (!thread_plan_sp && is_branch_island) {
       thread_plan_sp = std::make_shared<ThreadPlanStepInstruction>(
           thread,

lldb/test/API/macosx/branch-islands/TestBranchIslands.py

@@ -2,7 +2,7 @@
 Make sure that we can step in across an arm64 branch island
 """
 
-
+import os
 import lldb
 import lldbsuite.test.lldbutil as lldbutil
 from lldbsuite.test.lldbtest import *
@@ -32,6 +32,9 @@ def do_test(self):
         trace_before = lldbutil.print_stacktrace(thread, True)
         func_before = thread.frames[0].function
 
+        log_file_path = os.path.join(self.getBuildDir(), "step-log.txt")
+        self.runCmd(f"log enable -f {log_file_path} lldb step")
+        
         thread.StepInto()
         stop_frame = thread.frames[0]
         # This is failing on the bot, but I can't reproduce the failure
@@ -59,6 +62,10 @@ def do_test(self):
             print(
                 f"\nStop disassembly:\n {lldbutil.disassemble(target, stop_frame.function)}"
             )
+            with open(log_file_path, "r") as f:
+                data = f.read()
+                print("Step Log:")
+                print(data)
 
         self.assertIn("foo", stop_frame.name, "Stepped into foo")
         var = stop_frame.FindVariable("a_variable_in_foo")