[PATCH] D48868: [LLDB] In ProcessGDBRemote::UpdateThreadIDList(), the thread PCs should not be cleared after they are updated from the stop reply packet

[Jason Molenda via Phabricator via llvm-commits]

jasonmolenda added a subscriber: ramana-nvr.
jasonmolenda added a comment.

That's a good point Pavel.  I tried to write one (below) but I never saw what the original failure mode was.  Venkata, can you help to make a test case that fails before the patch and works after?  Or explain what bug was being fixed exactly?  I could see that the code was wrong from reading it, but I never understood how you got to this.

Index: packages/Python/lldbsuite/test/functionalities/gdb_remote_client/TestStopPCs.py
======================================================================================

- packages/Python/lldbsuite/test/functionalities/gdb_remote_client/TestStopPCs.py	(nonexistent)

+++ packages/Python/lldbsuite/test/functionalities/gdb_remote_client/TestStopPCs.py	(working copy)
@@ -0,0 +1,45 @@
+from __future__ import print_function
+import lldb
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test.decorators import *
+from gdbclientutils import *
+
+
+class TestThreadSelectionBug(GDBRemoteTestBase):
+    def test(self):
+        class MyResponder(MockGDBServerResponder):
+            def haltReason(self):
+                return "T02thread:1ff0d;threads:1ff0d,2ff0d;thread-pcs:10001bc00,10002bc00;"
+
+            def threadStopInfo(self, threadnum):
+                if threadnum == 0x1ff0d:
+                    return "T02thread:1ff0d;threads:1ff0d,2ff0d;thread-pcs:10001bc00,10002bc00;0:0,1:00bc010001;"
+                if threadnum == 0x2ff0d:
+                    return "T00thread:2ff0d;threads:1ff0d,2ff0d;thread-pcs:10001bc00,10002bc00;0:0,1:00bc020001;"
+
+            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="rax" bitsize="64" regnum="0" type="int" group="general"/>
+                            <reg name="rip" bitsize="64" regnum="1" type="code_ptr" group="general"/>
+                          </feature>
+                        </target>""", False
+                else:
+                    return None, False
+
+        self.server.responder = MyResponder()
+        target = self.dbg.CreateTarget('')
+        if self.TraceOn():
+          self.runCmd("log enable gdb-remote packets")
+        process = self.connect(target)
+
+        self.assertEqual(process.GetNumThreads(), 2)
+        th0 = process.GetThreadAtIndex(0)
+        th1 = process.GetThreadAtIndex(1)
+        self.assertEqual(th0.GetThreadID(), 0x1ff0d)
+        self.assertEqual(th1.GetThreadID(), 0x2ff0d)
+        self.assertEqual(th0.GetFrameAtIndex(0).GetPC(), 0x10001bc00)
+        self.assertEqual(th1.GetFrameAtIndex(0).GetPC(), 0x10002bc00)

Index: packages/Python/lldbsuite/test/functionalities/gdb_remote_client/gdbclientutils.py
=========================================================================================

- packages/Python/lldbsuite/test/functionalities/gdb_remote_client/gdbclientutils.py	(revision 337215)

+++ packages/Python/lldbsuite/test/functionalities/gdb_remote_client/gdbclientutils.py	(working copy)
@@ -130,6 +130,8 @@

      return self.QEnableErrorStrings()
  if packet == "?":
      return self.haltReason()

+        if packet == "s":
+            return self.haltReason()

  if packet[0] == "H":
      return self.selectThread(packet[1], int(packet[2:], 16))
  if packet[0:6] == "qXfer:":

@@ -144,6 +146,9 @@

      return self.vAttach(int(pid, 16))
  if packet[0] == "Z":
      return self.setBreakpoint(packet)

+        if packet.startswith("qThreadStopInfo"):
+            threadnum = int (packet[15:], 16)
+            return self.threadStopInfo(threadnum)

      return self.other(packet)
   
  def interrupt(self):

@@ -204,6 +209,9 @@

  def setBreakpoint(self, packet):
      raise self.UnexpectedPacketException()
   

+    def threadStopInfo(self, threadnum):
+        return ""
+

  def other(self, packet):
      # empty string means unsupported
      return ""


Repository:
  rL LLVM

https://reviews.llvm.org/D48868