Add option to pass thread ID to thread select command (#73596)

We'd like a way to select the current thread by its thread ID (rather
than its internal LLDB thread index).

This PR adds a `-t` option (`--thread_id` long option) that tells the
`thread select` command to interpret the `<thread-index>` argument as a
thread ID.

Here's an example of it working:
```
michristensen@devbig356 llvm/llvm-project (thread-select-tid) » ../Debug/bin/lldb ~/scratch/cpp/threading/a.out
(lldb) target create "/home/michristensen/scratch/cpp/threading/a.out"
Current executable set to '/home/michristensen/scratch/cpp/threading/a.out' (x86_64).
(lldb) b 18
Breakpoint 1: where = a.out`main + 80 at main.cpp:18:12, address = 0x0000000000000850
(lldb) run
Process 215715 launched: '/home/michristensen/scratch/cpp/threading/a.out' (x86_64)
This is a thread, i=1
This is a thread, i=2
This is a thread, i=3
This is a thread, i=4
This is a thread, i=5
Process 215715 stopped
* thread #1, name = 'a.out', stop reason = breakpoint 1.1
    frame #0: 0x0000555555400850 a.out`main at main.cpp:18:12
   15     for (int i = 0; i < 5; i++) {
   16       pthread_create(&thread_ids[i], NULL, foo, NULL);
   17     }
-> 18     for (int i = 0; i < 5; i++) {
   19       pthread_join(thread_ids[i], NULL);
   20     }
   21     return 0;
(lldb) thread select 2
* thread #2, name = 'a.out'
    frame #0: 0x00007ffff68f9918 libc.so.6`__nanosleep + 72
libc.so.6`__nanosleep:
->  0x7ffff68f9918 <+72>: cmpq   $-0x1000, %rax ; imm = 0xF000
    0x7ffff68f991e <+78>: ja     0x7ffff68f9952 ; <+130>
    0x7ffff68f9920 <+80>: movl   %edx, %edi
    0x7ffff68f9922 <+82>: movl   %eax, 0xc(%rsp)
(lldb) thread info
thread #2: tid = 216047, 0x00007ffff68f9918 libc.so.6`__nanosleep + 72, name = 'a.out'

(lldb) thread list
Process 215715 stopped
  thread #1: tid = 215715, 0x0000555555400850 a.out`main at main.cpp:18:12, name = 'a.out', stop reason = breakpoint 1.1
* thread #2: tid = 216047, 0x00007ffff68f9918 libc.so.6`__nanosleep + 72, name = 'a.out'
  thread #3: tid = 216048, 0x00007ffff68f9918 libc.so.6`__nanosleep + 72, name = 'a.out'
  thread #4: tid = 216049, 0x00007ffff68f9918 libc.so.6`__nanosleep + 72, name = 'a.out'
  thread #5: tid = 216050, 0x00007ffff68f9918 libc.so.6`__nanosleep + 72, name = 'a.out'
  thread intel#6: tid = 216051, 0x00007ffff68f9918 libc.so.6`__nanosleep + 72, name = 'a.out'
(lldb) thread select 215715
error: invalid thread #215715.
(lldb) thread select -t 215715
* thread #1, name = 'a.out', stop reason = breakpoint 1.1
    frame #0: 0x0000555555400850 a.out`main at main.cpp:18:12
   15     for (int i = 0; i < 5; i++) {
   16       pthread_create(&thread_ids[i], NULL, foo, NULL);
   17     }
-> 18     for (int i = 0; i < 5; i++) {
   19       pthread_join(thread_ids[i], NULL);
   20     }
   21     return 0;
(lldb) thread select -t 216051
* thread intel#6, name = 'a.out'
    frame #0: 0x00007ffff68f9918 libc.so.6`__nanosleep + 72
libc.so.6`__nanosleep:
->  0x7ffff68f9918 <+72>: cmpq   $-0x1000, %rax ; imm = 0xF000
    0x7ffff68f991e <+78>: ja     0x7ffff68f9952 ; <+130>
    0x7ffff68f9920 <+80>: movl   %edx, %edi
    0x7ffff68f9922 <+82>: movl   %eax, 0xc(%rsp)
(lldb) thread select 3
* thread #3, name = 'a.out'
    frame #0: 0x00007ffff68f9918 libc.so.6`__nanosleep + 72
libc.so.6`__nanosleep:
->  0x7ffff68f9918 <+72>: cmpq   $-0x1000, %rax ; imm = 0xF000
    0x7ffff68f991e <+78>: ja     0x7ffff68f9952 ; <+130>
    0x7ffff68f9920 <+80>: movl   %edx, %edi
    0x7ffff68f9922 <+82>: movl   %eax, 0xc(%rsp)
(lldb) thread select -t 216048
* thread #3, name = 'a.out'
    frame #0: 0x00007ffff68f9918 libc.so.6`__nanosleep + 72
libc.so.6`__nanosleep:
->  0x7ffff68f9918 <+72>: cmpq   $-0x1000, %rax ; imm = 0xF000
    0x7ffff68f991e <+78>: ja     0x7ffff68f9952 ; <+130>
    0x7ffff68f9920 <+80>: movl   %edx, %edi
    0x7ffff68f9922 <+82>: movl   %eax, 0xc(%rsp)
(lldb) thread select --thread_id 216048
* thread #3, name = 'a.out'
    frame #0: 0x00007ffff68f9918 libc.so.6`__nanosleep + 72
libc.so.6`__nanosleep:
->  0x7ffff68f9918 <+72>: cmpq   $-0x1000, %rax ; imm = 0xF000
    0x7ffff68f991e <+78>: ja     0x7ffff68f9952 ; <+130>
    0x7ffff68f9920 <+80>: movl   %edx, %edi
    0x7ffff68f9922 <+82>: movl   %eax, 0xc(%rsp)
(lldb) help thread select
Change the currently selected thread.

Syntax: thread select <cmd-options> <thread-index>

Command Options Usage:
  thread select [-t] <thread-index>

       -t ( --thread_id )
            Provide a thread ID instead of a thread index.

     This command takes options and free-form arguments.  If your arguments
     resemble option specifiers (i.e., they start with a - or --), you must use
     ' -- ' between the end of the command options and the beginning of the
     arguments.
(lldb) c
Process 215715 resuming
Process 215715 exited with status = 0 (0x00000000)
```

lldb/include/lldb/Interpreter/CommandCompletions.h

@@ -120,6 +120,9 @@ class CommandCompletions {
                                 CompletionRequest &request,
                                 SearchFilter *searcher);
 
+  static void ThreadIDs(CommandInterpreter &interpreter,
+                        CompletionRequest &request, SearchFilter *searcher);
+
   /// This completer works for commands whose only arguments are a command path.
   /// It isn't tied to an argument type because it completes not on a single
   /// argument but on the sequence of arguments, so you have to invoke it by

lldb/include/lldb/Interpreter/CommandOptionArgumentTable.h

@@ -192,6 +192,7 @@ static constexpr OptionEnumValueElement g_completion_type[] = {
     {lldb::eTypeCategoryNameCompletion, "type-category-name",
      "Completes to a type category name."},
     {lldb::eCustomCompletion, "custom", "Custom completion."},
+    {lldb::eThreadIDCompletion, "thread-id", "Completes to a thread ID."},
 };
 
 llvm::StringRef RegisterNameHelpTextCallback();

lldb/include/lldb/lldb-enumerations.h

@@ -1270,36 +1270,38 @@ enum WatchpointValueKind {
 };
 
 enum CompletionType {
-  eNoCompletion = 0u,
-  eSourceFileCompletion = (1u << 0),
-  eDiskFileCompletion = (1u << 1),
-  eDiskDirectoryCompletion = (1u << 2),
-  eSymbolCompletion = (1u << 3),
-  eModuleCompletion = (1u << 4),
-  eSettingsNameCompletion = (1u << 5),
-  ePlatformPluginCompletion = (1u << 6),
-  eArchitectureCompletion = (1u << 7),
-  eVariablePathCompletion = (1u << 8),
-  eRegisterCompletion = (1u << 9),
-  eBreakpointCompletion = (1u << 10),
-  eProcessPluginCompletion = (1u << 11),
-  eDisassemblyFlavorCompletion = (1u << 12),
-  eTypeLanguageCompletion = (1u << 13),
-  eFrameIndexCompletion = (1u << 14),
-  eModuleUUIDCompletion = (1u << 15),
-  eStopHookIDCompletion = (1u << 16),
-  eThreadIndexCompletion = (1u << 17),
-  eWatchpointIDCompletion = (1u << 18),
-  eBreakpointNameCompletion = (1u << 19),
-  eProcessIDCompletion = (1u << 20),
-  eProcessNameCompletion = (1u << 21),
-  eRemoteDiskFileCompletion = (1u << 22),
-  eRemoteDiskDirectoryCompletion = (1u << 23),
-  eTypeCategoryNameCompletion = (1u << 24),
-  // This item serves two purposes.  It is the last element in the enum, so
-  // you can add custom enums starting from here in your Option class. Also
-  // if you & in this bit the base code will not process the option.
-  eCustomCompletion = (1u << 25)
+  eNoCompletion = 0ul,
+  eSourceFileCompletion = (1ul << 0),
+  eDiskFileCompletion = (1ul << 1),
+  eDiskDirectoryCompletion = (1ul << 2),
+  eSymbolCompletion = (1ul << 3),
+  eModuleCompletion = (1ul << 4),
+  eSettingsNameCompletion = (1ul << 5),
+  ePlatformPluginCompletion = (1ul << 6),
+  eArchitectureCompletion = (1ul << 7),
+  eVariablePathCompletion = (1ul << 8),
+  eRegisterCompletion = (1ul << 9),
+  eBreakpointCompletion = (1ul << 10),
+  eProcessPluginCompletion = (1ul << 11),
+  eDisassemblyFlavorCompletion = (1ul << 12),
+  eTypeLanguageCompletion = (1ul << 13),
+  eFrameIndexCompletion = (1ul << 14),
+  eModuleUUIDCompletion = (1ul << 15),
+  eStopHookIDCompletion = (1ul << 16),
+  eThreadIndexCompletion = (1ul << 17),
+  eWatchpointIDCompletion = (1ul << 18),
+  eBreakpointNameCompletion = (1ul << 19),
+  eProcessIDCompletion = (1ul << 20),
+  eProcessNameCompletion = (1ul << 21),
+  eRemoteDiskFileCompletion = (1ul << 22),
+  eRemoteDiskDirectoryCompletion = (1ul << 23),
+  eTypeCategoryNameCompletion = (1ul << 24),
+  eCustomCompletion = (1ul << 25),
+  eThreadIDCompletion = (1ul << 26),
+  // This last enum element is just for input validation.
+  // Add new completions before this element,
+  // and then increment eTerminatorCompletion's shift value
+  eTerminatorCompletion = (1ul << 27)
 };
 
 } // namespace lldb

lldb/source/Commands/CommandCompletions.cpp

@@ -44,7 +44,7 @@ typedef void (*CompletionCallback)(CommandInterpreter &interpreter,
                                    lldb_private::SearchFilter *searcher);
 
 struct CommonCompletionElement {
-  uint32_t type;
+  uint64_t type;
   CompletionCallback callback;
 };
 
@@ -54,6 +54,7 @@ bool CommandCompletions::InvokeCommonCompletionCallbacks(
   bool handled = false;
 
   const CommonCompletionElement common_completions[] = {
+      {lldb::eNoCompletion, nullptr},
       {lldb::eSourceFileCompletion, CommandCompletions::SourceFiles},
       {lldb::eDiskFileCompletion, CommandCompletions::DiskFiles},
       {lldb::eDiskDirectoryCompletion, CommandCompletions::DiskDirectories},
@@ -83,12 +84,13 @@ bool CommandCompletions::InvokeCommonCompletionCallbacks(
        CommandCompletions::RemoteDiskDirectories},
       {lldb::eTypeCategoryNameCompletion,
        CommandCompletions::TypeCategoryNames},
-      {lldb::CompletionType::eNoCompletion,
+      {lldb::eThreadIDCompletion, CommandCompletions::ThreadIDs},
+      {lldb::eTerminatorCompletion,
        nullptr} // This one has to be last in the list.
   };
 
   for (int i = 0;; i++) {
-    if (common_completions[i].type == lldb::eNoCompletion)
+    if (common_completions[i].type == lldb::eTerminatorCompletion)
       break;
     else if ((common_completions[i].type & completion_mask) ==
                  common_completions[i].type &&
@@ -807,6 +809,23 @@ void CommandCompletions::TypeCategoryNames(CommandInterpreter &interpreter,
       });
 }
 
+void CommandCompletions::ThreadIDs(CommandInterpreter &interpreter,
+                                   CompletionRequest &request,
+                                   SearchFilter *searcher) {
+  const ExecutionContext &exe_ctx = interpreter.GetExecutionContext();
+  if (!exe_ctx.HasProcessScope())
+    return;
+
+  ThreadList &threads = exe_ctx.GetProcessPtr()->GetThreadList();
+  lldb::ThreadSP thread_sp;
+  for (uint32_t idx = 0; (thread_sp = threads.GetThreadAtIndex(idx)); ++idx) {
+    StreamString strm;
+    thread_sp->GetStatus(strm, 0, 1, 1, true);
+    request.TryCompleteCurrentArg(std::to_string(thread_sp->GetID()),
+                                  strm.GetString());
+  }
+}
+
 void CommandCompletions::CompleteModifiableCmdPathArgs(
     CommandInterpreter &interpreter, CompletionRequest &request,
     OptionElementVector &opt_element_vector) {

lldb/source/Commands/CommandObjectThread.cpp

@@ -1129,11 +1129,51 @@ class CommandObjectThreadUntil : public CommandObjectParsed {
 
 // CommandObjectThreadSelect
 
+#define LLDB_OPTIONS_thread_select
+#include "CommandOptions.inc"
+
 class CommandObjectThreadSelect : public CommandObjectParsed {
 public:
+  class OptionGroupThreadSelect : public OptionGroup {
+  public:
+    OptionGroupThreadSelect() { OptionParsingStarting(nullptr); }
+
+    ~OptionGroupThreadSelect() override = default;
+
+    void OptionParsingStarting(ExecutionContext *execution_context) override {
+      m_thread_id = LLDB_INVALID_THREAD_ID;
+    }
+
+    Status SetOptionValue(uint32_t option_idx, llvm::StringRef option_arg,
+                          ExecutionContext *execution_context) override {
+      const int short_option = g_thread_select_options[option_idx].short_option;
+      switch (short_option) {
+      case 't': {
+        if (option_arg.getAsInteger(0, m_thread_id)) {
+          m_thread_id = LLDB_INVALID_THREAD_ID;
+          return Status("Invalid thread ID: '%s'.", option_arg.str().c_str());
+        }
+        break;
+      }
+
+      default:
+        llvm_unreachable("Unimplemented option");
+      }
+
+      return {};
+    }
+
+    llvm::ArrayRef<OptionDefinition> GetDefinitions() override {
+      return llvm::ArrayRef(g_thread_select_options);
+    }
+
+    lldb::tid_t m_thread_id;
+  };
+
   CommandObjectThreadSelect(CommandInterpreter &interpreter)
       : CommandObjectParsed(interpreter, "thread select",
-                            "Change the currently selected thread.", nullptr,
+                            "Change the currently selected thread.",
+                            "thread select <thread-index> (or -t <thread-id>)",
                             eCommandRequiresProcess | eCommandTryTargetAPILock |
                                 eCommandProcessMustBeLaunched |
                                 eCommandProcessMustBePaused) {
@@ -1143,13 +1183,17 @@ class CommandObjectThreadSelect : public CommandObjectParsed {
     // Define the first (and only) variant of this arg.
     thread_idx_arg.arg_type = eArgTypeThreadIndex;
     thread_idx_arg.arg_repetition = eArgRepeatPlain;
+    thread_idx_arg.arg_opt_set_association = LLDB_OPT_SET_1;
 
     // There is only one variant this argument could be; put it into the
     // argument entry.
     arg.push_back(thread_idx_arg);
 
     // Push the data for the first argument into the m_arguments vector.
     m_arguments.push_back(arg);
+
+    m_option_group.Append(&m_options, LLDB_OPT_SET_ALL, LLDB_OPT_SET_2);
+    m_option_group.Finalize();
   }
 
   ~CommandObjectThreadSelect() override = default;
@@ -1165,37 +1209,59 @@ class CommandObjectThreadSelect : public CommandObjectParsed {
         nullptr);
   }
 
+  Options *GetOptions() override { return &m_option_group; }
+
 protected:
   void DoExecute(Args &command, CommandReturnObject &result) override {
     Process *process = m_exe_ctx.GetProcessPtr();
     if (process == nullptr) {
       result.AppendError("no process");
       return;
-    } else if (command.GetArgumentCount() != 1) {
+    } else if (m_options.m_thread_id == LLDB_INVALID_THREAD_ID &&
+               command.GetArgumentCount() != 1) {
       result.AppendErrorWithFormat(
-          "'%s' takes exactly one thread index argument:\nUsage: %s\n",
+          "'%s' takes exactly one thread index argument, or a thread ID "
+          "option:\nUsage: %s\n",
           m_cmd_name.c_str(), m_cmd_syntax.c_str());
       return;
-    }
-
-    uint32_t index_id;
-    if (!llvm::to_integer(command.GetArgumentAtIndex(0), index_id)) {
-      result.AppendErrorWithFormat("Invalid thread index '%s'",
-                                   command.GetArgumentAtIndex(0));
+    } else if (m_options.m_thread_id != LLDB_INVALID_THREAD_ID &&
+               command.GetArgumentCount() != 0) {
+      result.AppendErrorWithFormat("'%s' cannot take both a thread ID option "
+                                   "and a thread index argument:\nUsage: %s\n",
+                                   m_cmd_name.c_str(), m_cmd_syntax.c_str());
       return;
     }
 
-    Thread *new_thread =
-        process->GetThreadList().FindThreadByIndexID(index_id).get();
-    if (new_thread == nullptr) {
-      result.AppendErrorWithFormat("invalid thread #%s.\n",
-                                   command.GetArgumentAtIndex(0));
-      return;
+    Thread *new_thread = nullptr;
+    if (command.GetArgumentCount() == 1) {
+      uint32_t index_id;
+      if (!llvm::to_integer(command.GetArgumentAtIndex(0), index_id)) {
+        result.AppendErrorWithFormat("Invalid thread index '%s'",
+                                     command.GetArgumentAtIndex(0));
+        return;
+      }
+      new_thread = process->GetThreadList().FindThreadByIndexID(index_id).get();
+      if (new_thread == nullptr) {
+        result.AppendErrorWithFormat("Invalid thread index #%s.\n",
+                                     command.GetArgumentAtIndex(0));
+        return;
+      }
+    } else {
+      new_thread =
+          process->GetThreadList().FindThreadByID(m_options.m_thread_id).get();
+      if (new_thread == nullptr) {
+        result.AppendErrorWithFormat("Invalid thread ID %" PRIu64 ".\n",
+                                     m_options.m_thread_id);
+        return;
+      }
     }
 
     process->GetThreadList().SetSelectedThreadByID(new_thread->GetID(), true);
     result.SetStatus(eReturnStatusSuccessFinishNoResult);
   }
+
+  OptionGroupThreadSelect m_options;
+  OptionGroupOptions m_option_group;
 };
 
 // CommandObjectThreadList

lldb/source/Commands/Options.td

@@ -1117,6 +1117,12 @@ let Command = "thread plan list" in {
     Desc<"Display thread plans for unreported threads">;
 }
 
+let Command = "thread select" in {
+  def thread_select_thread_id : Option<"thread-id", "t">, Group<2>,
+    Arg<"ThreadID">, Completion<"ThreadID">,
+    Desc<"Provide a thread ID instead of a thread index.">;
+}
+
 let Command = "thread trace dump function calls" in {
   def thread_trace_dump_function_calls_file : Option<"file", "F">, Group<1>,
     Arg<"Filename">,

lldb/test/API/commands/thread/select/TestThreadSelect.py

@@ -12,17 +12,44 @@ def test_invalid_arg(self):
             self, "// break here", lldb.SBFileSpec("main.cpp")
         )
 
-        self.expect(
-            "thread select -1", error=True, startstr="error: Invalid thread index '-1'"
-        )
         self.expect(
             "thread select 0x1ffffffff",
             error=True,
             startstr="error: Invalid thread index '0x1ffffffff'",
         )
+        self.expect(
+            "thread select -t 0x1ffffffff",
+            error=True,
+            startstr="error: Invalid thread ID",
+        )
+        self.expect(
+            "thread select 1 2 3",
+            error=True,
+            startstr="error: 'thread select' takes exactly one thread index argument, or a thread ID option:",
+        )
+        self.expect(
+            "thread select -t 1234 1",
+            error=True,
+            startstr="error: 'thread select' cannot take both a thread ID option and a thread index argument:",
+        )
         # Parses but not a valid thread id.
         self.expect(
             "thread select 0xffffffff",
             error=True,
-            startstr="error: invalid thread #0xffffffff.",
+            startstr="error: Invalid thread index #0xffffffff.",
+        )
+        self.expect(
+            "thread select -t 0xffffffff",
+            error=True,
+            startstr="error: Invalid thread ID",
+        )
+
+    def test_thread_select_tid(self):
+        self.build()
+
+        lldbutil.run_to_source_breakpoint(
+            self, "// break here", lldb.SBFileSpec("main.cpp")
+        )
+        self.runCmd(
+            "thread select -t %d" % self.thread().GetThreadID(),
         )