Make sure the thread list is updated before you set the stop reason

on a thread.  When talking to some older gdb-remote stubs, We were getting
a stop reason from the stop reply packet and setting it on the relevant
thread before we updated the full stop list.  That would get discarded when
the full list was updated.

Also, if you already have a thread list when you go to see if there is an
Operating System plugin, and you do indeed load a new OS plugin, you have to
re-fetch the thread list or it will only show the raw threads.

Differential Revision: https://reviews.llvm.org/D62887

llvm-svn: 364666
(cherry picked from commit 8864b43)

Author: jimingham

lldb/packages/Python/lldbsuite/test/functionalities/gdb_remote_client/TestRecognizeBreakpoint.py

@@ -0,0 +1,139 @@
+from __future__ import print_function
+import lldb
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test.decorators import *
+from gdbclientutils import *
+
+
+class TestRecognizeBreakpoint(GDBRemoteTestBase):
+    """ This tests the case where the gdb-remote server doesn't support any
+        of the thread-info packets, and just tells which thread got the stop
+        signal with:
+              T05thread:01;
+        There was a bug in lldb that we would set the stop reason from this 
+        packet too early - before we had updated the thread list.  So when we
+        later updated the thread list, we would throw away this info.  Normally
+        we would be able to reconstruct it from the thread info, but not if the
+        stub doesn't support it """
+             
+    def test(self):
+        class MyResponder(MockGDBServerResponder):
+            def __init__(self):
+                MockGDBServerResponder.__init__(self)
+                self.thread_info_count = 0
+                self.after_cont = False
+                self.current_thread = 0
+                
+            def cont(self):
+                # Simulate process stopping due to a breakpoint:
+                self.after_cont = True
+                return "T05thread:01;"
+
+            def vCont(self, packet):
+                self.after_cont = True
+                return "T05thread:01;"
+            
+            def haltReason(self):
+                return "T02thread:01;"
+
+            def threadStopInfo(self, num):
+                return ""
+
+            def QThreadSuffixSupported(self):
+                return ""
+
+            def QListThreadsInStopReply(self):
+                return ""
+
+            def setBreakpoint(self, packet):
+                return "OK"
+            
+            def qfThreadInfo(self):
+                return "m1"
+
+            def qsThreadInfo(self):
+                if (self.thread_info_count % 2) == 0:
+                    str = "m2"
+                else:
+                    str = "l"
+                self.thread_info_count += 1
+                return str
+
+            def readRegisters(self):
+                if self.after_cont and self.current_thread == 1:
+                    return "c01e990080ffffff"
+                else:
+                    return "badcfe10325476980"
+            
+            def readRegister(self, regno):
+                return ""
+            
+            def qXferRead(self, obj, annex, offset, length):
+                if annex == "target.xml":
+                    return """<?xml version="1.0"?>
+			<target version="1.0">
+                          <architecture>i386:x86-64</architecture>
+                          <feature name="org.gnu.gdb.i386.core">
+                            <reg name="rip" bitsize="64" regnum="0" type="code_ptr" group="general"/>
+                          </feature>
+                        </target>""", False
+		else:
+                    return None, False
+
+            def selectThread(self, op, thread):
+                if op != 'g':
+                    return ''
+                
+                self.current_thread = thread
+                return "OK"
+            
+            def other (self, packet):
+                if packet == "vCont?":
+                    return "vCont;c;C;s;S"
+                return ''
+                
+        python_os_plugin_path = os.path.join(self.getSourceDir(),
+                                             'operating_system_2.py')
+        command ="settings set target.process.python-os-plugin-path '{}'".format(
+            python_os_plugin_path)
+        self.runCmd(command)
+
+        self.server.responder = MyResponder()
+        target = self.dbg.CreateTarget("")
+        process = self.connect(target)
+
+        bkpt = target.BreakpointCreateByAddress(0xffffff8000991ec0)
+        self.assertEqual(bkpt.GetNumLocations(), 1, "Fake breakpoint was resolved.")
+
+        # Get the initial stop, and we should have two threads.
+        num_threads = len(process.threads)
+        self.assertEqual(num_threads, 2, "Got two threads")
+
+        thread_0 = process.threads[0]
+        self.assertEqual(thread_0.GetStopReason(), 1, "Thread_0 stopped for no reason")
+        self.assertEqual(thread_0.GetName(), "one", "Thread_0 is called one")
+        
+        thread_1 = process.threads[1]
+        self.assertEqual(thread_1.GetStopReason(), 5, "Thread_0 stopped for SIGSTOP")
+        self.assertEqual(thread_1.GetName(), "two", "Thread_0 is called two")
+        
+        # Now continue and we will fake hitting a breakpoint.
+        process.Continue()
+
+        self.assertEqual(process.GetState(),lldb.eStateStopped, "Process is stopped")
+        num_threads = len(process.threads)
+
+        num_threads = len(process.threads)
+        self.assertEqual(num_threads, 2, "Got two threads")
+
+        thread_0 = process.threads[0]
+        self.assertEqual(thread_0.GetStopReason(), 1, "Thread_0 stopped for no reason")
+        self.assertEqual(thread_0.GetName(), "one", "Thread_0 is called one")
+        
+        thread_1 = process.threads[1]
+        self.assertEqual(thread_1.GetStopReason(), 3, "Thread_0 stopped for SIGTRAP")
+        self.assertEqual(thread_1.GetName(), "three", "Thread_0 is called three")
+
+        self.assertTrue(thread_1.IsValid(), "Thread_1 is valid")
+        self.assertEqual(thread_1.GetStopReason(), lldb.eStopReasonBreakpoint, "Stopped at breakpoint")
+        

lldb/packages/Python/lldbsuite/test/functionalities/gdb_remote_client/gdbclientutils.py

@@ -103,6 +103,8 @@ def respond(self, packet):
             return self.interrupt()
         if packet == "c":
             return self.cont()
+        if packet.startswith("vCont;c"):
+            return self.vCont(packet)
         if packet[0] == "g":
             return self.readRegisters()
         if packet[0] == "G":
@@ -168,6 +170,9 @@ def interrupt(self):
     def cont(self):
         raise self.UnexpectedPacketException()
 
+    def vCont(self, packet):
+        raise self.UnexpectedPacketException()
+    
     def readRegisters(self):
         return "00000000" * self.registerCount
 

lldb/packages/Python/lldbsuite/test/functionalities/gdb_remote_client/operating_system_2.py

@@ -0,0 +1,62 @@
+import lldb
+import struct
+
+
+class OperatingSystemPlugIn(object):
+    """Class that provides data for an instance of a LLDB 'OperatingSystemPython' plug-in class
+       This version stops once with threads 0x111 and 0x222, then stops a second time with threads
+       0x111 and 0x333."""
+
+    def __init__(self, process):
+        '''Initialization needs a valid.SBProcess object.
+
+        This plug-in will get created after a live process is valid and has stopped for the first time.
+        '''
+        self.process = None
+        self.registers = None
+        self.threads = None
+        self.times_called = 0
+        if isinstance(process, lldb.SBProcess) and process.IsValid():
+            self.process = process
+            self.threads = None  # Will be an dictionary containing info for each thread
+
+    def get_target(self):
+        return self.process.target
+
+    def get_thread_info(self):
+        self.times_called += 1
+
+        if self.times_called == 1:
+            self.threads = [{
+                'tid': 0x111,
+                'name': 'one',
+                'queue': 'queue1',
+                'state': 'stopped',
+                'stop_reason': 'none',
+                'core': 1
+            }, {
+                'tid': 0x222,
+                'name': 'two',
+                'queue': 'queue2',
+                'state': 'stopped',
+                'stop_reason': 'none',
+                'core': 0
+            }]
+        else:
+            self.threads = [{
+                'tid': 0x111,
+                'name': 'one',
+                'queue': 'queue1',
+                'state': 'stopped',
+                'stop_reason': 'none',
+                'core': 1
+            }, {
+                'tid': 0x333,
+                'name': 'three',
+                'queue': 'queue3',
+                'state': 'stopped',
+                'stop_reason': 'none',
+                'core': 0
+            }]
+        return self.threads
+

lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp

@@ -2423,6 +2423,15 @@ void ProcessGDBRemote::RefreshStateAfterStop() {
 
   // Scope for the lock
   {
+    // Check to see if SetThreadStopInfo() filled in m_thread_ids?
+    if (m_thread_ids.empty()) {
+        // No, we need to fetch the thread list manually
+        UpdateThreadIDList();
+    }
+    // We might set some stop info's so make sure the thread list is up to
+    // date before we do that or we might overwrite what was computed here.
+    UpdateThreadListIfNeeded();
+
     // Lock the thread stack while we access it
     std::lock_guard<std::recursive_mutex> guard(m_last_stop_packet_mutex);
     // Get the number of stop packets on the stack
@@ -2437,13 +2446,7 @@ void ProcessGDBRemote::RefreshStateAfterStop() {
     // Clear the thread stop stack
     m_stop_packet_stack.clear();
   }
-
-  // Check to see if SetThreadStopInfo() filled in m_thread_ids?
-  if (m_thread_ids.empty()) {
-    // No, we need to fetch the thread list manually
-    UpdateThreadIDList();
-  }
-
+  
   // If we have queried for a default thread id
   if (m_initial_tid != LLDB_INVALID_THREAD_ID) {
     m_thread_list.SetSelectedThreadByID(m_initial_tid);

lldb/source/Target/Process.cpp

@@ -3019,8 +3019,16 @@ void Process::CompleteAttach() {
     }
   }
 
-  if (!m_os_up)
+  if (!m_os_up) {
     LoadOperatingSystemPlugin(false);
+    if (m_os_up) {
+      // Somebody might have gotten threads before now, but we need to force the
+      // update after we've loaded the OperatingSystem plugin or it won't get a
+      // chance to process the threads.
+      m_thread_list.Clear();
+      UpdateThreadListIfNeeded();
+    }
+  }
   // Figure out which one is the executable, and set that in our target:
   const ModuleList &target_modules = GetTarget().GetImages();
   std::lock_guard<std::recursive_mutex> guard(target_modules.GetMutex());