[LLDB][swift] Add test demonstrating failed async variable inspection

Author: felipepiovezan

lldb/test/API/lang/swift/async/frame/variables_multiple_frames/Makefile

@@ -0,0 +1,3 @@
+SWIFT_SOURCES := main.swift
+SWIFTFLAGS_EXTRAS := -parse-as-library
+include Makefile.rules

lldb/test/API/lang/swift/async/frame/variables_multiple_frames/TestSwiftAsyncFrameVarMultipleFrames.py

@@ -0,0 +1,78 @@
+import lldb
+from lldbsuite.test.decorators import *
+import lldbsuite.test.lldbtest as lldbtest
+import lldbsuite.test.lldbutil as lldbutil
+
+
+class TestCase(lldbtest.TestBase):
+
+    mydir = lldbtest.TestBase.compute_mydir(__file__)
+
+    # Check that the CFA chain is correctly built
+    def check_cfas(self, async_frames, process):
+        async_cfas = list(map(lambda frame: frame.GetCFA(), async_frames))
+        expected_cfas = [async_cfas[0]]
+        # The CFA chain ends in nullptr.
+        while expected_cfas[-1] != 0:
+            error = lldb.SBError()
+            expected_cfas.append(
+                process.ReadPointerFromMemory(expected_cfas[-1], error)
+            )
+            self.assertSuccess(error, "Managed to read cfa memory")
+
+        self.assertEqual(async_cfas, expected_cfas[:-1])
+
+    def check_pcs(self, async_frames, process, target):
+        for idx, frame in enumerate(async_frames[:-1]):
+            # Read the continuation pointer from the second field of the CFA.
+            error = lldb.SBError()
+            continuation_ptr = process.ReadPointerFromMemory(
+                frame.GetCFA() + target.addr_size, error
+            )
+            self.assertSuccess(error, "Managed to read context memory")
+
+            # The PC of the previous frame should be the continuation pointer
+            # with the funclet's prologue skipped.
+            parent_frame = async_frames[idx + 1]
+            prologue_to_skip = parent_frame.GetFunction().GetPrologueByteSize()
+            self.assertEqual(continuation_ptr + prologue_to_skip, parent_frame.GetPC())
+
+
+    def check_variables(self, async_frames, expected_values):
+        for (frame, expected_value) in zip(async_frames, expected_values):
+            myvar = frame.FindVariable("myvar")
+            lldbutil.check_variable(self, myvar, False, value=expected_value)
+
+    @swiftTest
+    @skipIf(oslist=["windows", "linux", "macos"])
+    def test(self):
+        """Test `frame variable` in async functions"""
+        self.build()
+
+        source_file = lldb.SBFileSpec("main.swift")
+        target, process, _, _ = lldbutil.run_to_source_breakpoint(
+            self, "breakpoint1", source_file
+        )
+
+        async_frames = process.GetSelectedThread().frames
+        self.check_cfas(async_frames, process)
+        self.check_pcs(async_frames, process, target)
+        self.check_variables(async_frames, ["222", "333", "444", "555"])
+
+        target.DeleteAllBreakpoints()
+        target.BreakpointCreateBySourceRegex("breakpoint2", source_file)
+        process.Continue()
+        # First frame is from a synchronous function
+        frames = process.GetSelectedThread().frames
+        async_frames = frames[1:]
+        self.check_cfas(async_frames, process)
+        self.check_pcs(async_frames, process, target)
+        self.check_variables(async_frames, ["111", "222", "333", "444", "555"])
+
+        target.DeleteAllBreakpoints()
+        target.BreakpointCreateBySourceRegex("breakpoint3", source_file)
+        process.Continue()
+        async_frames = process.GetSelectedThread().frames
+        self.check_cfas(async_frames, process)
+        self.check_pcs(async_frames, process, target)
+        self.check_variables(async_frames, ["222", "333", "444", "555"])

lldb/test/API/lang/swift/async/frame/variables_multiple_frames/main.swift

@@ -0,0 +1,49 @@
+func work() {
+  print("working") // breakpoint2
+}
+
+func ASYNC___1___() async -> Int {
+  var myvar = 111;
+  work()
+  myvar += 1;
+  return myvar
+}
+
+func ASYNC___2___() async -> Int {
+  var myvar = 222;
+  let result = await ASYNC___1___() // breakpoint1
+  work() // breakpoint3
+  myvar += result;
+  return myvar
+}
+
+func ASYNC___3___() async -> Int {
+  var myvar = 333;
+  let result = await ASYNC___2___()
+  work()
+  myvar += result
+  return myvar
+}
+
+func ASYNC___4___() async -> Int {
+  var myvar = 444;
+  let result = await ASYNC___3___()
+  work()
+  myvar += result
+  return myvar
+}
+
+func ASYNC___5___() async -> Int {
+  var myvar = 555;
+  let result = await ASYNC___4___()
+  work()
+  myvar += result
+  return myvar
+}
+
+@main struct Main {
+  static func main() async {
+    let result = await ASYNC___5___()
+    print(result)
+  }
+}