https://github.com/felipepiovezan updated
https://github.com/llvm/llvm-project/pull/125300
>From 0c9d9ed5b1aa78f397e95c894def54ee627bea62 Mon Sep 17 00:00:00 2001
From: Felipe de Azevedo Piovezan <fpiove...@apple.com>
Date: Fri, 31 Jan 2025 12:07:45 -0800
Subject: [PATCH 1/4] [lldb] Implement bidirectional access for
backing<->backed thread relationship
This enables finding the backed thread from the backing thread without
going through the thread list, and it will be useful for subsequent
commits.
---
lldb/include/lldb/Target/Thread.h | 15 +++++++++++++++
lldb/include/lldb/Target/ThreadList.h | 2 --
.../source/Plugins/Process/Utility/ThreadMemory.h | 7 ++++++-
.../Process/gdb-remote/ProcessGDBRemote.cpp | 2 +-
lldb/source/Target/ThreadList.cpp | 14 --------------
5 files changed, 22 insertions(+), 18 deletions(-)
diff --git a/lldb/include/lldb/Target/Thread.h
b/lldb/include/lldb/Target/Thread.h
index ef66fa11574db9..d5fe33586fa3cf 100644
--- a/lldb/include/lldb/Target/Thread.h
+++ b/lldb/include/lldb/Target/Thread.h
@@ -470,6 +470,18 @@ class Thread : public std::enable_shared_from_this<Thread>,
virtual void ClearStackFrames();
+ /// Derived classes implementing SetBackingThread should use this to provide
+ /// bidirectional access to the Backing-Backed relationship.
+ void SetBackedThread(Thread &backed_thread) {
+ assert(backed_thread.GetBackingThread().get() == this);
+ m_backed_thread = backed_thread.shared_from_this();
+ }
+
+ void ClearBackedThread() { m_backed_thread.reset(); }
+
+ /// Returns the thread that is backed by this thread, if any.
+ lldb::ThreadSP GetBackedThread() const { return m_backed_thread; }
+
virtual bool SetBackingThread(const lldb::ThreadSP &thread_sp) {
return false;
}
@@ -1349,6 +1361,9 @@ class Thread : public
std::enable_shared_from_this<Thread>,
LazyBool m_override_should_notify;
mutable std::unique_ptr<ThreadPlanStack> m_null_plan_stack_up;
+ /// The Thread backed by this thread, if any.
+ lldb::ThreadSP m_backed_thread;
+
private:
bool m_extended_info_fetched; // Have we tried to retrieve the
m_extended_info
// for this thread?
diff --git a/lldb/include/lldb/Target/ThreadList.h
b/lldb/include/lldb/Target/ThreadList.h
index f931bb83a8ceaf..bca01f5fe2083e 100644
--- a/lldb/include/lldb/Target/ThreadList.h
+++ b/lldb/include/lldb/Target/ThreadList.h
@@ -101,8 +101,6 @@ class ThreadList : public ThreadCollection {
lldb::ThreadSP GetThreadSPForThreadPtr(Thread *thread_ptr);
- lldb::ThreadSP GetBackingThread(const lldb::ThreadSP &real_thread);
-
bool ShouldStop(Event *event_ptr);
Vote ShouldReportStop(Event *event_ptr);
diff --git a/lldb/source/Plugins/Process/Utility/ThreadMemory.h
b/lldb/source/Plugins/Process/Utility/ThreadMemory.h
index d124f5780ea9bd..1e309671e85c65 100644
--- a/lldb/source/Plugins/Process/Utility/ThreadMemory.h
+++ b/lldb/source/Plugins/Process/Utility/ThreadMemory.h
@@ -72,12 +72,17 @@ class ThreadMemory : public lldb_private::Thread {
void ClearStackFrames() override;
- void ClearBackingThread() override { m_backing_thread_sp.reset(); }
+ void ClearBackingThread() override {
+ if (m_backing_thread_sp)
+ m_backing_thread_sp->ClearBackedThread();
+ m_backing_thread_sp.reset();
+ }
bool SetBackingThread(const lldb::ThreadSP &thread_sp) override {
// printf ("Thread 0x%llx is being backed by thread 0x%llx\n", GetID(),
// thread_sp->GetID());
m_backing_thread_sp = thread_sp;
+ thread_sp->SetBackedThread(*this);
return (bool)thread_sp;
}
diff --git a/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
b/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
index 21a0fa283644d6..3f34ea2930a66a 100644
--- a/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
+++ b/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
@@ -1728,7 +1728,7 @@ ThreadSP ProcessGDBRemote::SetThreadStopInfo(
thread_sp->SetStopInfo(StopInfoSP());
// If there's a memory thread backed by this thread, we need to use it to
// calculate StopInfo.
- if (ThreadSP memory_thread_sp = m_thread_list.GetBackingThread(thread_sp))
+ if (ThreadSP memory_thread_sp = thread_sp->GetBackedThread())
thread_sp = memory_thread_sp;
if (exc_type != 0) {
diff --git a/lldb/source/Target/ThreadList.cpp
b/lldb/source/Target/ThreadList.cpp
index 6cbef330bf4888..c0440d82fd1ffc 100644
--- a/lldb/source/Target/ThreadList.cpp
+++ b/lldb/source/Target/ThreadList.cpp
@@ -191,20 +191,6 @@ ThreadSP ThreadList::GetThreadSPForThreadPtr(Thread
*thread_ptr) {
return thread_sp;
}
-ThreadSP ThreadList::GetBackingThread(const ThreadSP &real_thread) {
- std::lock_guard<std::recursive_mutex> guard(GetMutex());
-
- ThreadSP thread_sp;
- const uint32_t num_threads = m_threads.size();
- for (uint32_t idx = 0; idx < num_threads; ++idx) {
- if (m_threads[idx]->GetBackingThread() == real_thread) {
- thread_sp = m_threads[idx];
- break;
- }
- }
- return thread_sp;
-}
-
ThreadSP ThreadList::FindThreadByIndexID(uint32_t index_id, bool can_update) {
std::lock_guard<std::recursive_mutex> guard(GetMutex());
>From b19eb1c1e438f12785775e5e063c926a8c863843 Mon Sep 17 00:00:00 2001
From: Felipe de Azevedo Piovezan <fpiove...@apple.com>
Date: Fri, 31 Jan 2025 16:54:10 -0800
Subject: [PATCH 2/4] fixup! Address review comments
---
lldb/include/lldb/Target/Thread.h | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)
diff --git a/lldb/include/lldb/Target/Thread.h
b/lldb/include/lldb/Target/Thread.h
index d5fe33586fa3cf..35a71b3761ebe1 100644
--- a/lldb/include/lldb/Target/Thread.h
+++ b/lldb/include/lldb/Target/Thread.h
@@ -470,11 +470,19 @@ class Thread : public
std::enable_shared_from_this<Thread>,
virtual void ClearStackFrames();
- /// Derived classes implementing SetBackingThread should use this to provide
- /// bidirectional access to the Backing-Backed relationship.
+ /// Sets the thread that is backed by this thread.
+ /// If backed_thread.GetBackedThread() is null, this method also calls
+ /// backed_thread.SetBackedThread(this).
+ /// If backed_thread.GetBackedThread() is non-null, asserts that it is equal
+ /// to `this`.
void SetBackedThread(Thread &backed_thread) {
- assert(backed_thread.GetBackingThread().get() == this);
m_backed_thread = backed_thread.shared_from_this();
+
+ // Ensure the bidrectional relationship is preserved.
+ Thread *backing_thread = backed_thread.GetBackingThread().get();
+ assert(backing_thread == nullptr || backing_thread == this);
+ if (backing_thread == nullptr)
+ backed_thread.SetBackingThread(shared_from_this());
}
void ClearBackedThread() { m_backed_thread.reset(); }
>From c54af403582377bf4749683323d0228059a86622 Mon Sep 17 00:00:00 2001
From: Felipe de Azevedo Piovezan <fpiove...@apple.com>
Date: Fri, 31 Jan 2025 17:06:41 -0800
Subject: [PATCH 3/4] fixup! Fix documentation typo
---
lldb/include/lldb/Target/Thread.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/lldb/include/lldb/Target/Thread.h
b/lldb/include/lldb/Target/Thread.h
index 35a71b3761ebe1..3af8a516918a39 100644
--- a/lldb/include/lldb/Target/Thread.h
+++ b/lldb/include/lldb/Target/Thread.h
@@ -472,7 +472,7 @@ class Thread : public std::enable_shared_from_this<Thread>,
/// Sets the thread that is backed by this thread.
/// If backed_thread.GetBackedThread() is null, this method also calls
- /// backed_thread.SetBackedThread(this).
+ /// backed_thread.SetBackingThread(this).
/// If backed_thread.GetBackedThread() is non-null, asserts that it is equal
/// to `this`.
void SetBackedThread(Thread &backed_thread) {
>From 1882d04ac380b9ac36527679c9c550269d13b4f8 Mon Sep 17 00:00:00 2001
From: Felipe de Azevedo Piovezan <fpiove...@apple.com>
Date: Mon, 3 Feb 2025 08:03:14 -0800
Subject: [PATCH 4/4] fixup! Break circular shared_ptr references
---
lldb/include/lldb/Target/Thread.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/lldb/include/lldb/Target/Thread.h
b/lldb/include/lldb/Target/Thread.h
index 3af8a516918a39..9749fd8d575a1c 100644
--- a/lldb/include/lldb/Target/Thread.h
+++ b/lldb/include/lldb/Target/Thread.h
@@ -488,7 +488,7 @@ class Thread : public std::enable_shared_from_this<Thread>,
void ClearBackedThread() { m_backed_thread.reset(); }
/// Returns the thread that is backed by this thread, if any.
- lldb::ThreadSP GetBackedThread() const { return m_backed_thread; }
+ lldb::ThreadSP GetBackedThread() const { return m_backed_thread.lock(); }
virtual bool SetBackingThread(const lldb::ThreadSP &thread_sp) {
return false;
@@ -1370,7 +1370,7 @@ class Thread : public
std::enable_shared_from_this<Thread>,
mutable std::unique_ptr<ThreadPlanStack> m_null_plan_stack_up;
/// The Thread backed by this thread, if any.
- lldb::ThreadSP m_backed_thread;
+ lldb::ThreadWP m_backed_thread;
private:
bool m_extended_info_fetched; // Have we tried to retrieve the
m_extended_info
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