[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 llvm#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;