[lldb][test] Fix TestEmptyFuncThreadStepOut.py

The test did not work as intended when the empty function 'done()'
contained epilog code, because a breakpoint was set on the first
instruction of the epilog instead of on the last instruction of the
function. This caused the test to pass even with the fix from #126838
reverted.

Author: igorkudrin

lldb/test/API/functionalities/thread/finish-from-empty-func/TestEmptyFuncThreadStepOut.py

@@ -15,10 +15,23 @@ class FinishFromEmptyFunctionTestCase(TestBase):
     def test_finish_from_empty_function(self):
         """Test that when stopped at a breakpoint in an empty function, finish leaves it correctly."""
         self.build()
-        exe = self.getBuildArtifact("a.out")
-        target, process, thread, _ = lldbutil.run_to_name_breakpoint(
-            self, "done", exe_name=exe
+        target, _, thread, _ = lldbutil.run_to_source_breakpoint(
+            self, "// Set breakpoint here", lldb.SBFileSpec("main.c")
         )
+        # Find the last instruction address of 'done()' and set a breakpoint there.
+        error = lldb.SBError()
+        ret_bp_addr = lldb.SBAddress()
+        while True:
+            thread.StepInstruction(False, error)
+            self.assertTrue(error.Success())
+            frame = thread.GetSelectedFrame()
+            if "done" in frame.GetFunctionName():
+                ret_bp_addr = frame.GetPCAddress()
+            elif ret_bp_addr.IsValid():
+                break
+        ret_bp = target.BreakpointCreateByAddress(ret_bp_addr.GetLoadAddress(target))
+        self.assertTrue(ret_bp.IsValid())
+        self.runCmd("cont")
         if self.TraceOn():
             self.runCmd("bt")
 
@@ -29,7 +42,6 @@ def test_finish_from_empty_function(self):
         )
         self.assertTrue(safety_bp.IsValid())
 
-        error = lldb.SBError()
         thread.StepOut(error)
         self.assertTrue(error.Success())
 

lldb/test/API/functionalities/thread/finish-from-empty-func/main.c

@@ -2,6 +2,7 @@
 void done() {}
 int main() {
   puts("in main");
+  done(); // Set breakpoint here
   done();
   puts("leaving main");
   return 0;