https://github.com/felipepiovezan created
https://github.com/llvm/llvm-project/pull/129275
When OS plugins are present, it can be helpful to query information about the
backing thread behind an OS thread, if it exists. There is no mechanism to do
so prior to this commit.
As a first step, this commit enhances `thread info` with a `--backing-thread`
flag, causing the command to use the backing thread of the selected thread, if
it exists.
>From cd6661b5fb7a9a71352c79740d4b0c0601e61d43 Mon Sep 17 00:00:00 2001
From: Felipe de Azevedo Piovezan <fpiove...@apple.com>
Date: Fri, 28 Feb 2025 09:11:11 -0800
Subject: [PATCH] [lldb] Add ability to inspect backing threads with `thread
info`
When OS plugins are present, it can be helpful to query information
about the backing thread behind an OS thread, if it exists. There is no
mechanism to do so prior to this commit.
As a first step, this commit enhances `thread info` with a
`--backing-thread` flag, causing the command to use the backing thread
of the selected thread, if it exists.
---
lldb/source/Commands/CommandObjectThread.cpp | 8 +++++++
lldb/source/Commands/Options.td | 3 +++
.../python_os_plugin/TestPythonOSPlugin.py | 24 +++++++++++++++++++
3 files changed, 35 insertions(+)
diff --git a/lldb/source/Commands/CommandObjectThread.cpp
b/lldb/source/Commands/CommandObjectThread.cpp
index cd3d2d89333f1..224c523e69c5c 100644
--- a/lldb/source/Commands/CommandObjectThread.cpp
+++ b/lldb/source/Commands/CommandObjectThread.cpp
@@ -1270,6 +1270,7 @@ class CommandObjectThreadInfo : public
CommandObjectIterateOverThreads {
void OptionParsingStarting(ExecutionContext *execution_context) override {
m_json_thread = false;
m_json_stopinfo = false;
+ m_backing_thread = false;
}
Status SetOptionValue(uint32_t option_idx, llvm::StringRef option_arg,
@@ -1286,6 +1287,10 @@ class CommandObjectThreadInfo : public
CommandObjectIterateOverThreads {
m_json_stopinfo = true;
break;
+ case 'b':
+ m_backing_thread = true;
+ break;
+
default:
llvm_unreachable("Unimplemented option");
}
@@ -1298,6 +1303,7 @@ class CommandObjectThreadInfo : public
CommandObjectIterateOverThreads {
bool m_json_thread;
bool m_json_stopinfo;
+ bool m_backing_thread;
};
CommandObjectThreadInfo(CommandInterpreter &interpreter)
@@ -1334,6 +1340,8 @@ class CommandObjectThreadInfo : public
CommandObjectIterateOverThreads {
}
Thread *thread = thread_sp.get();
+ if (m_options.m_backing_thread && thread->GetBackingThread())
+ thread = thread->GetBackingThread().get();
Stream &strm = result.GetOutputStream();
if (!thread->GetDescription(strm, eDescriptionLevelFull,
diff --git a/lldb/source/Commands/Options.td b/lldb/source/Commands/Options.td
index 8831fed38435b..cc579d767eb06 100644
--- a/lldb/source/Commands/Options.td
+++ b/lldb/source/Commands/Options.td
@@ -1108,6 +1108,9 @@ let Command = "thread info" in {
" JSON format.">;
def thread_info_stop_info : Option<"stop-info", "s">, Desc<"Display the "
"extended stop info in JSON format.">;
+ def thread_info_backing_thread : Option<"backing-thread", "b">,
+ Desc<"If this is an OS plugin thread, query the backing thread instead;
has"
+ " no effect otherwise.">;
}
let Command = "thread return" in {
diff --git
a/lldb/test/API/functionalities/plugins/python_os_plugin/TestPythonOSPlugin.py
b/lldb/test/API/functionalities/plugins/python_os_plugin/TestPythonOSPlugin.py
index fe78edd98f4d4..33e4f75adc0d0 100644
---
a/lldb/test/API/functionalities/plugins/python_os_plugin/TestPythonOSPlugin.py
+++
b/lldb/test/API/functionalities/plugins/python_os_plugin/TestPythonOSPlugin.py
@@ -131,6 +131,25 @@ def run_python_os_funcionality(self):
"Make sure there is no thread 0x333333333 after we unload the
python OS plug-in",
)
+ tid_regex = re.compile("tid = (0x[0-9a-fA-F]+)")
+ def get_tid_from_thread_info_command(self, thread, use_backing_thread):
+ interp = self.dbg.GetCommandInterpreter()
+ result = lldb.SBCommandReturnObject()
+
+ backing_thread_arg = ""
+ if use_backing_thread:
+ backing_thread_arg = "--backing-thread"
+
+ interp.HandleCommand(
+ "thread info {0} {1}".format(thread.GetIndexID(),
backing_thread_arg),
+ result,
+ True,
+ )
+ self.assertTrue(result.Succeeded(), "failed to run thread info")
+ match = self.tid_regex.search(result.GetOutput())
+ self.assertNotEqual(match, None)
+ return match.group(1)
+
def run_python_os_step(self):
"""Test that the Python operating system plugin works correctly and
allows single stepping of a virtual thread that is backed by a real thread"""
@@ -209,6 +228,11 @@ def run_python_os_step(self):
# it to
thread.StepOver()
+ tid_os = self.get_tid_from_thread_info_command(thread, False)
+ self.assertEqual(tid_os, "0x111111111")
+ tid_real = self.get_tid_from_thread_info_command(thread, True)
+ self.assertNotEqual(tid_os, tid_real)
+
frame = thread.GetFrameAtIndex(0)
self.assertTrue(
frame.IsValid(), "Make sure we get a frame from thread 0x111111111"
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