[Lldb-commits] [lldb] [lldb] Add alternative SBThread::GetStopDescription (PR #165379)
Ebuka Ezike via lldb-commits
lldb-commits at lists.llvm.org
Tue Oct 28 05:09:04 PDT 2025
https://github.com/da-viper created https://github.com/llvm/llvm-project/pull/165379
the function signature for `GetStopDescription` is `lldb::SBThread::GetStopDescription(char *dst_or_null, size_t len)`.
To get a description you need to call the function first time to get the buffer size. a second time to get the description.
This is little worse from the python size as the signature is `lldb.SBThread.GetStopDescription(int: len) -> list[str]` the user has to pass the max size as possible with no way of checking if it is enough.
This patch adds a new api
`lldb.SBThread.GetStopDescription(desc: lldb.SBStream()) -> bool` `bool lldb::SBThread::GetStopDescription(lldb::SBStream &description)` which handles this case.
Adds test case for lua.
>From 4f3a47c4cf0347a14ef115100c7a73cb00cf0f66 Mon Sep 17 00:00:00 2001
From: Ebuka Ezike <yerimyah1 at gmail.com>
Date: Mon, 27 Oct 2025 16:02:27 +0000
Subject: [PATCH] [lldb] Add alternative SBThread::GetStopDescription
the function signature for `GetStopDescription` is
`lldb::SBThread::GetStopDescription(char *dst_or_null, size_t len)`
to get a description you need to call the function first time to get the
buffer size. and again to get the description.
This is little worse from the python size as the signature is
`lldb.SBThread.GetStopDescription(int: len) -> list[str]` the user has
to pass the max size as possible with no way of checking if it is enough.
This patch adds a new api
`lldb.SBThread.GetStopDescription(desc: lldb.SBStream()) -> bool`
`bool lldb::SBThread::GetStopDescription(lldb::SBStream &description)`
which handles this case.
---
lldb/bindings/lua/lua-typemaps.swig | 9 ++++-
lldb/bindings/python/python-typemaps.swig | 7 ++++
lldb/include/lldb/API/SBThread.h | 8 +++++
lldb/source/API/SBThread.cpp | 35 +++++++++++++++----
lldb/test/API/lua_api/TestThreadAPI.lua | 25 +++++++++++++
.../default-constructor/sb_thread.py | 1 +
.../API/python_api/thread/TestThreadAPI.py | 5 +++
lldb/tools/lldb-rpc-gen/RPCCommon.cpp | 1 +
8 files changed, 84 insertions(+), 7 deletions(-)
create mode 100644 lldb/test/API/lua_api/TestThreadAPI.lua
diff --git a/lldb/bindings/lua/lua-typemaps.swig b/lldb/bindings/lua/lua-typemaps.swig
index 56756936a532c..26163c1ad3328 100644
--- a/lldb/bindings/lua/lua-typemaps.swig
+++ b/lldb/bindings/lua/lua-typemaps.swig
@@ -121,9 +121,16 @@ LLDB_NUMBER_TYPEMAP(enum SWIGTYPE);
$1 = (char *)malloc($2);
}
+// Remove the default type check for this match.
+// because if the match function has an overload and a typemap,
+// it will typecheck against the original function instead of the
+// typemap.
+%typemap(typecheck, precedence=SWIG_TYPECHECK_POINTER) (char *dst_or_null, size_t dst_len) ""
+
%typemap(argout) (char *dst_or_null, size_t dst_len) {
lua_pop(L, 1); // Blow away the previous result
- lua_pushlstring(L, (const char *)$1, $result);
+ llvm::StringRef ref($1);
+ lua_pushlstring(L, (const char *)$1, ref.size());
free($1);
// SWIG_arg was already incremented
}
diff --git a/lldb/bindings/python/python-typemaps.swig b/lldb/bindings/python/python-typemaps.swig
index 715914fe745f8..a7fa40445b5d0 100644
--- a/lldb/bindings/python/python-typemaps.swig
+++ b/lldb/bindings/python/python-typemaps.swig
@@ -224,6 +224,13 @@ AND call SWIG_fail at the same time, because it will result in a double free.
}
$1 = (char *)malloc($2);
}
+
+// Remove the default type check for this match.
+// because if the match function has an overload and a typemap,
+// it will typecheck against the original function instead of the
+// typemap.
+%typemap(typecheck, precedence=SWIG_TYPECHECK_POINTER) (char *dst_or_null, size_t dst_len) ""
+
%typemap(argout) (char *dst_or_null, size_t dst_len) {
Py_XDECREF($result); /* Blow away any previous result */
llvm::StringRef ref($1);
diff --git a/lldb/include/lldb/API/SBThread.h b/lldb/include/lldb/API/SBThread.h
index e9fe5858d125e..2411dfd376519 100644
--- a/lldb/include/lldb/API/SBThread.h
+++ b/lldb/include/lldb/API/SBThread.h
@@ -81,6 +81,14 @@ class LLDB_API SBThread {
SBThreadCollection
GetStopReasonExtendedBacktraces(InstrumentationRuntimeType type);
+ /// Gets a human-readable description of why the thread stopped.
+ ///
+ /// \param stream Output stream to receive the stop description text
+ /// \return
+ /// true if obtained and written to the stream,
+ // false if there was an error retrieving the description.
+ bool GetStopDescription(lldb::SBStream &stream) const;
+
size_t GetStopDescription(char *dst_or_null, size_t dst_len);
SBValue GetStopReturnValue();
diff --git a/lldb/source/API/SBThread.cpp b/lldb/source/API/SBThread.cpp
index 4e4aa48bc9a2e..f58a1b52afa91 100644
--- a/lldb/source/API/SBThread.cpp
+++ b/lldb/source/API/SBThread.cpp
@@ -239,11 +239,34 @@ SBThread::GetStopReasonExtendedBacktraces(InstrumentationRuntimeType type) {
return threads;
}
-size_t SBThread::GetStopDescription(char *dst, size_t dst_len) {
- LLDB_INSTRUMENT_VA(this, dst, dst_len);
+bool SBThread::GetStopDescription(lldb::SBStream &stream) const {
+ LLDB_INSTRUMENT_VA(this, stream);
+
+ if (!m_opaque_sp)
+ return false;
+
+ llvm::Expected<StoppedExecutionContext> exe_ctx =
+ GetStoppedExecutionContext(m_opaque_sp);
+ if (!exe_ctx) {
+ LLDB_LOG_ERROR(GetLog(LLDBLog::API), exe_ctx.takeError(), "{0}");
+ return false;
+ }
+
+ if (!exe_ctx->HasThreadScope())
+ return false;
+
+ Stream &strm = stream.ref();
+ const std::string stop_desc = exe_ctx->GetThreadPtr()->GetStopDescription();
+ strm.PutCString(stop_desc);
+
+ return true;
+}
+
+size_t SBThread::GetStopDescription(char *dst_or_null, size_t dst_len) {
+ LLDB_INSTRUMENT_VA(this, dst_or_null, dst_len);
- if (dst)
- *dst = 0;
+ if (dst_or_null)
+ *dst_or_null = 0;
llvm::Expected<StoppedExecutionContext> exe_ctx =
GetStoppedExecutionContext(m_opaque_sp);
@@ -259,8 +282,8 @@ size_t SBThread::GetStopDescription(char *dst, size_t dst_len) {
if (thread_stop_desc.empty())
return 0;
- if (dst)
- return ::snprintf(dst, dst_len, "%s", thread_stop_desc.c_str()) + 1;
+ if (dst_or_null)
+ return ::snprintf(dst_or_null, dst_len, "%s", thread_stop_desc.c_str()) + 1;
// NULL dst passed in, return the length needed to contain the
// description.
diff --git a/lldb/test/API/lua_api/TestThreadAPI.lua b/lldb/test/API/lua_api/TestThreadAPI.lua
new file mode 100644
index 0000000000000..5a38d0ba9192f
--- /dev/null
+++ b/lldb/test/API/lua_api/TestThreadAPI.lua
@@ -0,0 +1,25 @@
+_T = require('lua_lldb_test').create_test('TestThreadAPI')
+
+function _T:TestGetStopDescription()
+ local target = self:create_target()
+ local breakpoint = target:BreakpointCreateByName("main", "a.out")
+ assertTrue(breakpoint:IsValid() and breakpoint:GetNumLocations() == 1)
+
+ local process = target:LaunchSimple({ 'arg1', 'arg2' }, nil, nil)
+ local thread = get_stopped_thread(process, lldb.eStopReasonBreakpoint)
+ assertNotNil(thread)
+ assertTrue(thread:IsValid())
+
+ assertEqual("breakpoint", thread:GetStopDescription(string.len("breakpoint") + 1))
+ assertEqual("break", thread:GetStopDescription(string.len("break") + 1))
+ assertEqual("b", thread:GetStopDescription(string.len("b") + 1))
+ assertEqual("breakpoint 1.1", thread:GetStopDescription(string.len("breakpoint 1.1") + 100))
+
+ -- Test stream variation
+ local stream = lldb.SBStream()
+ assertTrue(thread:GetStopDescription(stream))
+ assertNotNil(stream)
+ assertEqual("breakpoint 1.1", stream:GetData())
+end
+
+os.exit(_T:run())
diff --git a/lldb/test/API/python_api/default-constructor/sb_thread.py b/lldb/test/API/python_api/default-constructor/sb_thread.py
index 34eb3db852c38..4252fa0321fff 100644
--- a/lldb/test/API/python_api/default-constructor/sb_thread.py
+++ b/lldb/test/API/python_api/default-constructor/sb_thread.py
@@ -10,6 +10,7 @@ def fuzz_obj(obj):
obj.GetStopReasonDataCount()
obj.GetStopReasonDataAtIndex(100)
obj.GetStopDescription(256)
+ obj.GetStopDescription(lldb.SBStream())
obj.GetThreadID()
obj.GetIndexID()
obj.GetName()
diff --git a/lldb/test/API/python_api/thread/TestThreadAPI.py b/lldb/test/API/python_api/thread/TestThreadAPI.py
index 5583434a742a9..acad7583eec19 100644
--- a/lldb/test/API/python_api/thread/TestThreadAPI.py
+++ b/lldb/test/API/python_api/thread/TestThreadAPI.py
@@ -138,6 +138,11 @@ def get_stop_description(self):
"breakpoint 1.1", thread.GetStopDescription(len("breakpoint 1.1") + 100)
)
+ # Test the stream variation
+ stream = lldb.SBStream()
+ self.assertTrue(thread.GetStopDescription(stream))
+ self.assertEqual("breakpoint 1.1", stream.GetData())
+
def step_out_of_malloc_into_function_b(self, exe_name):
"""Test Python SBThread.StepOut() API to step out of a malloc call where the call site is at function b()."""
exe = self.getBuildArtifact(exe_name)
diff --git a/lldb/tools/lldb-rpc-gen/RPCCommon.cpp b/lldb/tools/lldb-rpc-gen/RPCCommon.cpp
index 7af6ee37f248b..5405f77b31d96 100644
--- a/lldb/tools/lldb-rpc-gen/RPCCommon.cpp
+++ b/lldb/tools/lldb-rpc-gen/RPCCommon.cpp
@@ -118,6 +118,7 @@ static constexpr llvm::StringRef MethodsWithPointerPlusLen[] = {
"_ZN4lldb8SBTarget15GetInstructionsEyPKvm",
"_ZN4lldb8SBTarget25GetInstructionsWithFlavorEyPKcPKvm",
"_ZN4lldb8SBThread18GetStopDescriptionEPcm",
+ "_ZNK4lldb8SBThread18GetStopDescriptionERNS_8SBStreamE",
// The below mangled names are used for dummy methods in shell tests
// that test the emitters' output. If you're adding any new mangled names
// from the actual SB API to this list please add them above.
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