Accommodate line-0 records in a test

[probinson]

Summary

LLVM is about to start emitting "line 0" records more often in the DWARF line table.
One test tripped over this; made the test accommodate the new records.

[probinson]

Forgot to mention this is for PR31214.

[jingham]

That's great. The source stepping should never have to do this by hand, so special casing the instruction stepping was perfect.

[jingham]

And remember to check the accept revision...

[probinson]

Thanks for helping to decipher the test result!

lldb/trunk/packages/Python/lldbsuite/test/functionalities/thread/exit_during_step/TestExitDuringStep.py

class ExitDuringStepTestCase(TestBase):
     mydir = TestBase.compute_mydir(__file__)
 
     @skipIfFreeBSD  # llvm.org/pr21411: test is hanging
     def test(self):
         """Test thread exit during step handling."""
         self.build(dictionary=self.getBuildFlags())
         self.exit_during_step_base(
             "thread step-inst -m all-threads",
-            'stop reason = instruction step')
+            'stop reason = instruction step',
+            True)
 
     @skipIfFreeBSD  # llvm.org/pr21411: test is hanging
     def test_step_over(self):
         """Test thread exit during step-over handling."""
         self.build(dictionary=self.getBuildFlags())
         self.exit_during_step_base(
             "thread step-over -m all-threads",
-            'stop reason = step over')
+            'stop reason = step over',
+            False)
 
     @skipIfFreeBSD  # llvm.org/pr21411: test is hanging
     def test_step_in(self):
         """Test thread exit during step-in handling."""
         self.build(dictionary=self.getBuildFlags())
         self.exit_during_step_base(
             "thread step-in -m all-threads",
-            'stop reason = step in')
+            'stop reason = step in',
+            False)
 
     def setUp(self):
         # Call super's setUp().
         TestBase.setUp(self)
         # Find the line numbers to break and continue.
         self.breakpoint = line_number('main.cpp', '// Set breakpoint here')
         self.continuepoint = line_number('main.cpp', '// Continue from here')
 
-    def exit_during_step_base(self, step_cmd, step_stop_reason):
+    def exit_during_step_base(self, step_cmd, step_stop_reason, by_instruction):
         """Test thread exit during step handling."""
         exe = os.path.join(os.getcwd(), "a.out")
         self.runCmd("file " + exe, CURRENT_EXECUTABLE_SET)
 
         # This should create a breakpoint in the main thread.
         self.bp_num = lldbutil.run_break_set_by_file_and_line(
             self, "main.cpp", self.breakpoint, num_expected_locations=1)
 
def exit_during_step_base(self, step_cmd, step_stop_reason, by_instruction):
                 process.SetSelectedThread(stepping_thread)
 
             self.runCmd(step_cmd)
 
             frame = stepping_thread.GetFrameAtIndex(0)
 
             current_line = frame.GetLineEntry().GetLine()
 
+            if by_instruction and current_line == 0:
+                continue
+
             self.assertGreaterEqual(
                 current_line,
                 self.breakpoint,
                 "Stepped to unexpected line, " +
                 str(current_line))
             self.assertLessEqual(
                 current_line,
                 self.continuepoint,