[lldb-dap] Improve stackTrace and exceptionInfo DAP request handlers (llvm#105905)

Refactoring `stackTrace` to perform frame look ups in a more on-demand
fashion to improve overall performance.

Additionally adding additional information to the `exceptionInfo`
request to report exception stacks there instead of merging the
exception stack into the stack trace. The `exceptionInfo` request is
only called if a stop event occurs with `reason='exception'`, which
should mitigate the performance of `SBThread::GetCurrentException`
calls.

Adding unit tests for exception handling and stack trace supporting.

(cherry picked from commit 5b4100c)

Author: ashgti

lldb/packages/Python/lldbsuite/test/lldbplatformutil.py

@@ -180,6 +180,22 @@ def findMainThreadCheckerDylib():
     return ""
 
 
+def findBacktraceRecordingDylib():
+    if not platformIsDarwin():
+        return ""
+
+    if getPlatform() in lldbplatform.translate(lldbplatform.darwin_embedded):
+        return "/Developer/usr/lib/libBacktraceRecording.dylib"
+
+    with os.popen("xcode-select -p") as output:
+        xcode_developer_path = output.read().strip()
+        mtc_dylib_path = "%s/usr/lib/libBacktraceRecording.dylib" % xcode_developer_path
+        if os.path.isfile(mtc_dylib_path):
+            return mtc_dylib_path
+
+    return ""
+
+
 class _PlatformContext(object):
     """Value object class which contains platform-specific options."""
 

lldb/packages/Python/lldbsuite/test/tools/lldb-dap/dap_server.py

@@ -707,6 +707,17 @@ def request_evaluate(self, expression, frameIndex=0, threadId=None, context=None
         }
         return self.send_recv(command_dict)
 
+    def request_exceptionInfo(self, threadId=None):
+        if threadId is None:
+            threadId = self.get_thread_id()
+        args_dict = {"threadId": threadId}
+        command_dict = {
+            "command": "exceptionInfo",
+            "type": "request",
+            "arguments": args_dict,
+        }
+        return self.send_recv(command_dict)
+
     def request_initialize(self, sourceInitFile):
         command_dict = {
             "command": "initialize",
@@ -754,6 +765,7 @@ def request_launch(
         runInTerminal=False,
         postRunCommands=None,
         enableAutoVariableSummaries=False,
+        enableDisplayExtendedBacktrace=False,
         enableSyntheticChildDebugging=False,
         commandEscapePrefix=None,
         customFrameFormat=None,
@@ -806,6 +818,7 @@ def request_launch(
 
         args_dict["enableAutoVariableSummaries"] = enableAutoVariableSummaries
         args_dict["enableSyntheticChildDebugging"] = enableSyntheticChildDebugging
+        args_dict["enableDisplayExtendedBacktrace"] = enableDisplayExtendedBacktrace
         args_dict["commandEscapePrefix"] = commandEscapePrefix
         command_dict = {"command": "launch", "type": "request", "arguments": args_dict}
         response = self.send_recv(command_dict)

lldb/packages/Python/lldbsuite/test/tools/lldb-dap/lldbdap_testcase.py

@@ -103,13 +103,14 @@ def verify_breakpoint_hit(self, breakpoint_ids):
                         return
         self.assertTrue(False, "breakpoint not hit")
 
-    def verify_stop_exception_info(self, expected_description):
+    def verify_stop_exception_info(self, expected_description, timeout=timeoutval):
         """Wait for the process we are debugging to stop, and verify the stop
         reason is 'exception' and that the description matches
         'expected_description'
         """
-        stopped_events = self.dap_server.wait_for_stopped()
+        stopped_events = self.dap_server.wait_for_stopped(timeout=timeout)
         for stopped_event in stopped_events:
+            print("stopped_event", stopped_event)
             if "body" in stopped_event:
                 body = stopped_event["body"]
                 if "reason" not in body:
@@ -180,6 +181,10 @@ def get_stackFrames(self, threadId=None, startFrame=None, levels=None, dump=Fals
         )
         return stackFrames
 
+    def get_exceptionInfo(self, threadId=None):
+        response = self.dap_server.request_exceptionInfo(threadId=threadId)
+        return self.get_dict_value(response, ["body"])
+
     def get_source_and_line(self, threadId=None, frameIndex=0):
         stackFrames = self.get_stackFrames(
             threadId=threadId, startFrame=frameIndex, levels=1
@@ -381,6 +386,7 @@ def launch(
         expectFailure=False,
         postRunCommands=None,
         enableAutoVariableSummaries=False,
+        enableDisplayExtendedBacktrace=False,
         enableSyntheticChildDebugging=False,
         commandEscapePrefix=None,
         customFrameFormat=None,
@@ -422,6 +428,7 @@ def cleanup():
             runInTerminal=runInTerminal,
             postRunCommands=postRunCommands,
             enableAutoVariableSummaries=enableAutoVariableSummaries,
+            enableDisplayExtendedBacktrace=enableDisplayExtendedBacktrace,
             enableSyntheticChildDebugging=enableSyntheticChildDebugging,
             commandEscapePrefix=commandEscapePrefix,
             customFrameFormat=customFrameFormat,
@@ -461,6 +468,7 @@ def build_and_launch(
         postRunCommands=None,
         lldbDAPEnv=None,
         enableAutoVariableSummaries=False,
+        enableDisplayExtendedBacktrace=False,
         enableSyntheticChildDebugging=False,
         commandEscapePrefix=None,
         customFrameFormat=None,
@@ -497,6 +505,7 @@ def build_and_launch(
             postRunCommands=postRunCommands,
             enableAutoVariableSummaries=enableAutoVariableSummaries,
             enableSyntheticChildDebugging=enableSyntheticChildDebugging,
+            enableDisplayExtendedBacktrace=enableDisplayExtendedBacktrace,
             commandEscapePrefix=commandEscapePrefix,
             customFrameFormat=customFrameFormat,
             customThreadFormat=customThreadFormat,

lldb/test/API/tools/lldb-dap/exception/Makefile

@@ -1,3 +1,3 @@
-CXX_SOURCES := main.cpp
+C_SOURCES := main.c
 
 include Makefile.rules

lldb/test/API/tools/lldb-dap/exception/TestDAP_exception.py

@@ -1,5 +1,5 @@
 """
-Test exception behavior in DAP
+Test exception behavior in DAP with signal.
 """
 
 
@@ -16,8 +16,10 @@ def test_stopped_description(self):
         event.
         """
         program = self.getBuildArtifact("a.out")
-        print("test_stopped_description called", flush=True)
         self.build_and_launch(program)
-
         self.dap_server.request_continue()
         self.assertTrue(self.verify_stop_exception_info("signal SIGABRT"))
+        exceptionInfo = self.get_exceptionInfo()
+        self.assertEqual(exceptionInfo["breakMode"], "always")
+        self.assertEqual(exceptionInfo["description"], "signal SIGABRT")
+        self.assertEqual(exceptionInfo["exceptionId"], "signal")

lldb/test/API/tools/lldb-dap/exception/cpp/Makefile

@@ -0,0 +1,3 @@
+CXX_SOURCES := main.cpp
+
+include Makefile.rules

lldb/test/API/tools/lldb-dap/exception/cpp/TestDAP_exception_cpp.py

@@ -0,0 +1,26 @@
+"""
+Test exception behavior in DAP with c++ throw.
+"""
+
+
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+import lldbdap_testcase
+
+
+class TestDAP_exception_cpp(lldbdap_testcase.DAPTestCaseBase):
+    @skipIfWindows
+    def test_stopped_description(self):
+        """
+        Test that exception description is shown correctly in stopped
+        event.
+        """
+        program = self.getBuildArtifact("a.out")
+        self.build_and_launch(program)
+        self.dap_server.request_continue()
+        self.assertTrue(self.verify_stop_exception_info("signal SIGABRT"))
+        exceptionInfo = self.get_exceptionInfo()
+        self.assertEqual(exceptionInfo["breakMode"], "always")
+        self.assertEqual(exceptionInfo["description"], "signal SIGABRT")
+        self.assertEqual(exceptionInfo["exceptionId"], "signal")
+        self.assertIsNotNone(exceptionInfo["details"])

lldb/test/API/tools/lldb-dap/exception/cpp/main.cpp

@@ -0,0 +1,6 @@
+#include <stdexcept>
+
+int main(int argc, char const *argv[]) {
+  throw std::invalid_argument("throwing exception for testing");
+  return 0;
+}

lldb/test/API/tools/lldb-dap/exception/main.cpp renamed to lldb/test/API/tools/lldb-dap/exception/main.c

@@ -1,6 +1,6 @@
 #include <signal.h>
 
-int main() {
+int main(int argc, char const *argv[]) {
   raise(SIGABRT);
   return 0;
 }

lldb/test/API/tools/lldb-dap/exception/objc/Makefile

@@ -0,0 +1,9 @@
+OBJC_SOURCES := main.m
+
+CFLAGS_EXTRAS := -w
+
+USE_SYSTEM_STDLIB := 1
+
+LD_EXTRAS := -framework Foundation
+
+include Makefile.rules

lldb/test/API/tools/lldb-dap/exception/objc/TestDAP_exception_objc.py

@@ -0,0 +1,27 @@
+"""
+Test exception behavior in DAP with obj-c throw.
+"""
+
+
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+import lldbdap_testcase
+
+
+class TestDAP_exception_objc(lldbdap_testcase.DAPTestCaseBase):
+    @skipUnlessDarwin
+    def test_stopped_description(self):
+        """
+        Test that exception description is shown correctly in stopped event.
+        """
+        program = self.getBuildArtifact("a.out")
+        self.build_and_launch(program)
+        self.dap_server.request_continue()
+        self.assertTrue(self.verify_stop_exception_info("signal SIGABRT"))
+        exception_info = self.get_exceptionInfo()
+        self.assertEqual(exception_info["breakMode"], "always")
+        self.assertEqual(exception_info["description"], "signal SIGABRT")
+        self.assertEqual(exception_info["exceptionId"], "signal")
+        exception_details = exception_info["details"]
+        self.assertRegex(exception_details["message"], "SomeReason")
+        self.assertRegex(exception_details["stackTrace"], "main.m")

lldb/test/API/tools/lldb-dap/exception/objc/main.m

@@ -0,0 +1,8 @@
+#import <Foundation/Foundation.h>
+
+int main(int argc, char const *argv[]) {
+  @throw [[NSException alloc] initWithName:@"ThrownException"
+                                    reason:@"SomeReason"
+                                  userInfo:nil];
+  return 0;
+}

lldb/test/API/tools/lldb-dap/extendedStackTrace/Makefile

@@ -0,0 +1,5 @@
+OBJC_SOURCES := main.m
+
+USE_SYSTEM_STDLIB := 1
+
+include Makefile.rules

lldb/test/API/tools/lldb-dap/extendedStackTrace/TestDAP_extendedStackTrace.py

@@ -0,0 +1,104 @@
+"""
+Test lldb-dap stackTrace request with an extended backtrace thread.
+"""
+
+
+import os
+
+import lldbdap_testcase
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test.lldbplatformutil import *
+
+
+class TestDAP_extendedStackTrace(lldbdap_testcase.DAPTestCaseBase):
+    @skipUnlessDarwin
+    def test_stackTrace(self):
+        """
+        Tests the 'stackTrace' packet on a thread with an extended backtrace.
+        """
+        backtrace_recording_lib = findBacktraceRecordingDylib()
+        if not backtrace_recording_lib:
+            self.skipTest(
+                "Skipped because libBacktraceRecording.dylib was present on the system."
+            )
+
+        if not os.path.isfile("/usr/lib/system/introspection/libdispatch.dylib"):
+            self.skipTest(
+                "Skipped because introspection libdispatch dylib is not present."
+            )
+
+        program = self.getBuildArtifact("a.out")
+
+        self.build_and_launch(
+            program,
+            env=[
+                "DYLD_LIBRARY_PATH=/usr/lib/system/introspection",
+                "DYLD_INSERT_LIBRARIES=" + backtrace_recording_lib,
+            ],
+            enableDisplayExtendedBacktrace=True,
+        )
+        source = "main.m"
+        breakpoint = line_number(source, "breakpoint 1")
+        lines = [breakpoint]
+
+        breakpoint_ids = self.set_source_breakpoints(source, lines)
+        self.assertEqual(
+            len(breakpoint_ids), len(lines), "expect correct number of breakpoints"
+        )
+
+        events = self.continue_to_next_stop()
+
+        stackFrames, totalFrames = self.get_stackFrames_and_totalFramesCount(
+            threadId=events[0]["body"]["threadId"]
+        )
+        self.assertGreaterEqual(len(stackFrames), 3, "expect >= 3 frames")
+        self.assertEqual(len(stackFrames), totalFrames)
+        self.assertEqual(stackFrames[0]["name"], "one")
+        self.assertEqual(stackFrames[1]["name"], "two")
+        self.assertEqual(stackFrames[2]["name"], "three")
+
+        stackLabels = [
+            (i, frame)
+            for i, frame in enumerate(stackFrames)
+            if frame.get("presentationHint", "") == "label"
+        ]
+        self.assertEqual(len(stackLabels), 2, "expected two label stack frames")
+        self.assertRegex(
+            stackLabels[0][1]["name"],
+            "Enqueued from com.apple.root.default-qos \(Thread \d\)",
+        )
+        self.assertRegex(
+            stackLabels[1][1]["name"],
+            "Enqueued from com.apple.main-thread \(Thread \d\)",
+        )
+
+        for i, frame in stackLabels:
+            # Ensure requesting startFrame+levels across thread backtraces works as expected.
+            stackFrames, totalFrames = self.get_stackFrames_and_totalFramesCount(
+                threadId=events[0]["body"]["threadId"], startFrame=i - 1, levels=3
+            )
+            self.assertEqual(len(stackFrames), 3, "expected 3 frames with levels=3")
+            self.assertGreaterEqual(
+                totalFrames, i + 3, "total frames should include a pagination offset"
+            )
+            self.assertEqual(stackFrames[1], frame)
+
+            # Ensure requesting startFrame+levels at the beginning of a thread backtraces works as expected.
+            stackFrames, totalFrames = self.get_stackFrames_and_totalFramesCount(
+                threadId=events[0]["body"]["threadId"], startFrame=i, levels=3
+            )
+            self.assertEqual(len(stackFrames), 3, "expected 3 frames with levels=3")
+            self.assertGreaterEqual(
+                totalFrames, i + 3, "total frames should include a pagination offset"
+            )
+            self.assertEqual(stackFrames[0], frame)
+
+            # Ensure requests with startFrame+levels that end precisely on the last frame includes the totalFrames pagination offset.
+            stackFrames, totalFrames = self.get_stackFrames_and_totalFramesCount(
+                threadId=events[0]["body"]["threadId"], startFrame=i - 1, levels=1
+            )
+            self.assertEqual(len(stackFrames), 1, "expected 1 frames with levels=1")
+            self.assertGreaterEqual(
+                totalFrames, i, "total frames should include a pagination offset"
+            )

lldb/test/API/tools/lldb-dap/extendedStackTrace/main.m

@@ -0,0 +1,28 @@
+#import <dispatch/dispatch.h>
+#include <stdio.h>
+
+void one() {
+  printf("one...\n"); // breakpoint 1
+}
+
+void two() {
+  printf("two...\n");
+  one();
+}
+
+void three() {
+  printf("three...\n");
+  two();
+}
+
+int main(int argc, char *argv[]) {
+  printf("main...\n");
+  // Nest from main queue > global queue > main queue.
+  dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0),
+                 ^{
+                   dispatch_async(dispatch_get_main_queue(), ^{
+                     three();
+                   });
+                 });
+  dispatch_main();
+}