[LLDB] Add data formatter for std::coroutine_handle

This patch adds a formatter for `std::coroutine_handle`, both for libc++
and libstdc++. For the type-erased `coroutine_handle<>`, it shows the
`resume` and `destroy` function pointers. For a non-type-erased
`coroutine_handle<promise_type>` it also shows the `promise` value.

With this change, executing the `v t` command on the example from
https://clang.llvm.org/docs/DebuggingCoroutines.html now outputs

```
(task) t = {
  handle = coro frame = 0x55555555b2a0 {
    resume = 0x0000555555555a10 (a.out`coro_task(int, int) at llvm-example.cpp:36)
    destroy = 0x0000555555556090 (a.out`coro_task(int, int) at llvm-example.cpp:36)
  }
}
```

instead of just

```
(task) t = {
  handle = {
    __handle_ = 0x55555555b2a0
  }
}
```

Note, how the symbols for the `resume` and `destroy` function pointer
reveal which coroutine is stored inside the `std::coroutine_handle`.
A follow-up commit will use this fact to infer the coroutine's promise
type and the representation of its internal coroutine state based on
the `resume` and `destroy` pointers.

The same formatter is used for both libc++ and libstdc++. It would
also work for MSVC's standard library, however it is not registered
for MSVC, given that lldb does not provide pretty printers for other
MSVC types, either.

The formatter is in a newly added  `Coroutines.{h,cpp}` file because there
does not seem to be an already existing place where we could share
formatters across libc++ and libstdc++. Also, I expect this code to grow
as we improve debugging experience for coroutines further.

**Testing**

* Added API test

Differential Revision: https://reviews.llvm.org/D132415

2 files changed, 21 insertions, 2 deletions

diff --git a/lldb/packages/Python/lldbsuite/test/lldbtest.py b/lldb/packages/Python/lldbsuite/test/lldbtest.py
index 69bb5ac..1c09039 100644
--- a/lldb/packages/Python/lldbsuite/test/lldbtest.py
+++ b/lldb/packages/Python/lldbsuite/test/lldbtest.py
@@ -292,8 +292,12 @@ class ValueCheck:
             test_base.assertEqual(self.expect_type, val.GetDisplayTypeName(),
                                   this_error_msg)
         if self.expect_summary:
-            test_base.assertEqual(self.expect_summary, val.GetSummary(),
-                                  this_error_msg)
+            if isinstance(self.expect_summary, re.Pattern):
+                test_base.assertRegex(val.GetSummary(), self.expect_summary,
+                                      this_error_msg)
+            else:
+                test_base.assertEqual(self.expect_summary, val.GetSummary(),
+                                      this_error_msg)
         if self.children is not None:
             self.check_value_children(test_base, val, error_msg)
 
diff --git a/lldb/packages/Python/lldbsuite/test/lldbutil.py b/lldb/packages/Python/lldbsuite/test/lldbutil.py
index 8bd49c7..7e64afb 100644
--- a/lldb/packages/Python/lldbsuite/test/lldbutil.py
+++ b/lldb/packages/Python/lldbsuite/test/lldbutil.py
@@ -988,6 +988,21 @@ def continue_to_breakpoint(process, bkpt):
         return get_threads_stopped_at_breakpoint(process, bkpt)
 
 
+def continue_to_source_breakpoint(test, process, bkpt_pattern, source_spec):
+    """
+    Sets a breakpoint set by source regex bkpt_pattern, continues the process, and deletes the breakpoint again.
+    Otherwise the same as `continue_to_breakpoint`
+    """
+    breakpoint = process.target.BreakpointCreateBySourceRegex(
+            bkpt_pattern, source_spec, None)
+    test.assertTrue(breakpoint.GetNumLocations() > 0,
+                    'No locations found for source breakpoint: "%s", file: "%s", dir: "%s"'
+                    %(bkpt_pattern, source_spec.GetFilename(), source_spec.GetDirectory()))
+    stopped_threads = continue_to_breakpoint(process, breakpoint)
+    process.target.BreakpointDelete(breakpoint.GetID())
+    return stopped_threads
+
+
 def get_caller_symbol(thread):
     """
     Returns the symbol name for the call site of the leaf function.