This revision was automatically updated to reflect the committed changes.
Closed by commit rL241434: Improve UnwindLLDB with better detection for
unwinding failures (authored by tberghammer).
Changed prior to commit:
http://reviews.llvm.org/D10932?vs=29029&id=29068#toc
Repository:
rL LLVM
http://reviews.llvm.org/D10932
Files:
lldb/trunk/source/Plugins/Process/Utility/UnwindLLDB.cpp
lldb/trunk/source/Plugins/Process/Utility/UnwindLLDB.h
Index: lldb/trunk/source/Plugins/Process/Utility/UnwindLLDB.h
===================================================================
--- lldb/trunk/source/Plugins/Process/Utility/UnwindLLDB.h
+++ lldb/trunk/source/Plugins/Process/Utility/UnwindLLDB.h
@@ -65,6 +65,7 @@
DoClear()
{
m_frames.clear();
+ m_candidate_frame.reset();
m_unwind_complete = false;
}
@@ -126,14 +127,21 @@
typedef std::shared_ptr<Cursor> CursorSP;
std::vector<CursorSP> m_frames;
+ CursorSP m_candidate_frame;
bool m_unwind_complete; // If this is true, we've enumerated all the frames in the stack, and m_frames.size() is the
// number of frames, etc. Otherwise we've only gone as far as directly asked, and m_frames.size()
// is how far we've currently gone.
std::vector<ConstString> m_user_supplied_trap_handler_functions;
- bool AddOneMoreFrame (ABI *abi);
- bool AddFirstFrame ();
+ CursorSP
+ GetOneMoreFrame (ABI* abi);
+
+ bool
+ AddOneMoreFrame (ABI *abi);
+
+ bool
+ AddFirstFrame ();
//------------------------------------------------------------------
// For UnwindLLDB only
Index: lldb/trunk/source/Plugins/Process/Utility/UnwindLLDB.cpp
===================================================================
--- lldb/trunk/source/Plugins/Process/Utility/UnwindLLDB.cpp
+++ lldb/trunk/source/Plugins/Process/Utility/UnwindLLDB.cpp
@@ -120,29 +120,28 @@
return false;
}
-// For adding a non-zero stack frame to m_frames.
-bool
-UnwindLLDB::AddOneMoreFrame (ABI *abi)
+UnwindLLDB::CursorSP
+UnwindLLDB::GetOneMoreFrame (ABI* abi)
{
+ assert (m_frames.size() != 0 && "Get one more frame called with empty frame list");
+
// If we've already gotten to the end of the stack, don't bother to try again...
if (m_unwind_complete)
- return false;
+ return nullptr;
Log *log(GetLogIfAllCategoriesSet (LIBLLDB_LOG_UNWIND));
- CursorSP cursor_sp(new Cursor ());
- // Frame zero is a little different
- if (m_frames.size() == 0)
- return false;
+ CursorSP prev_frame = m_frames.back();
+ uint32_t cur_idx = m_frames.size();
- uint32_t cur_idx = m_frames.size ();
+ CursorSP cursor_sp(new Cursor ());
RegisterContextLLDBSP reg_ctx_sp(new RegisterContextLLDB (m_thread,
- m_frames[cur_idx - 1]->reg_ctx_lldb_sp,
+ prev_frame->reg_ctx_lldb_sp,
cursor_sp->sctx,
cur_idx,
*this));
- // We want to detect an unwind that cycles erronously and stop backtracing.
+ // We want to detect an unwind that cycles erroneously and stop backtracing.
// Don't want this maximum unwind limit to be too low -- if you have a backtrace
// with an "infinitely recursing" bug, it will crash when the stack blows out
// and the first 35,000 frames are uninteresting - it's the top most 5 frames that
@@ -154,53 +153,46 @@
if (log)
log->Printf ("%*sFrame %d unwound too many frames, assuming unwind has gone astray, stopping.",
cur_idx < 100 ? cur_idx : 100, "", cur_idx);
- goto unwind_done;
+ return nullptr;
}
if (reg_ctx_sp.get() == NULL)
{
// If the RegisterContextLLDB has a fallback UnwindPlan, it will switch to that and return
// true. Subsequent calls to TryFallbackUnwindPlan() will return false.
- if (m_frames[cur_idx - 1]->reg_ctx_lldb_sp->TryFallbackUnwindPlan())
- {
- return AddOneMoreFrame (abi);
- }
+ if (prev_frame->reg_ctx_lldb_sp->TryFallbackUnwindPlan())
+ return GetOneMoreFrame (abi);
+
if (log)
log->Printf ("%*sFrame %d did not get a RegisterContext, stopping.",
cur_idx < 100 ? cur_idx : 100, "", cur_idx);
- goto unwind_done;
+ return nullptr;
}
if (!reg_ctx_sp->IsValid())
{
// We failed to get a valid RegisterContext.
// See if the regctx below this on the stack has a fallback unwind plan it can use.
// Subsequent calls to TryFallbackUnwindPlan() will return false.
- if (m_frames[cur_idx - 1]->reg_ctx_lldb_sp->TryFallbackUnwindPlan())
- {
- return AddOneMoreFrame (abi);
- }
+ if (prev_frame->reg_ctx_lldb_sp->TryFallbackUnwindPlan())
+ return GetOneMoreFrame (abi);
+
if (log)
- {
log->Printf("%*sFrame %d invalid RegisterContext for this frame, stopping stack walk",
cur_idx < 100 ? cur_idx : 100, "", cur_idx);
- }
- goto unwind_done;
+ return nullptr;
}
if (!reg_ctx_sp->GetCFA (cursor_sp->cfa))
{
// If the RegisterContextLLDB has a fallback UnwindPlan, it will switch to that and return
// true. Subsequent calls to TryFallbackUnwindPlan() will return false.
- if (m_frames[cur_idx - 1]->reg_ctx_lldb_sp->TryFallbackUnwindPlan())
- {
- return AddOneMoreFrame (abi);
- }
+ if (prev_frame->reg_ctx_lldb_sp->TryFallbackUnwindPlan())
+ return GetOneMoreFrame (abi);
+
if (log)
- {
log->Printf("%*sFrame %d did not get CFA for this frame, stopping stack walk",
cur_idx < 100 ? cur_idx : 100, "", cur_idx);
- }
- goto unwind_done;
+ return nullptr;
}
if (abi && !abi->CallFrameAddressIsValid(cursor_sp->cfa))
{
@@ -219,79 +211,123 @@
|| reg_ctx_sp->GetCFA (cursor_sp->cfa) == false
|| abi->CallFrameAddressIsValid(cursor_sp->cfa) == false)
{
- if (m_frames[cur_idx - 1]->reg_ctx_lldb_sp->TryFallbackUnwindPlan())
- {
- return AddOneMoreFrame (abi);
- }
+ if (prev_frame->reg_ctx_lldb_sp->TryFallbackUnwindPlan())
+ return GetOneMoreFrame (abi);
+
if (log)
- {
log->Printf("%*sFrame %d did not get a valid CFA for this frame, stopping stack walk",
cur_idx < 100 ? cur_idx : 100, "", cur_idx);
- }
- goto unwind_done;
+ return nullptr;
}
else
{
if (log)
- {
log->Printf("%*sFrame %d had a bad CFA value but we switched the UnwindPlan being used and got one that looks more realistic.",
cur_idx < 100 ? cur_idx : 100, "", cur_idx);
- }
}
}
}
if (!reg_ctx_sp->ReadPC (cursor_sp->start_pc))
{
// If the RegisterContextLLDB has a fallback UnwindPlan, it will switch to that and return
// true. Subsequent calls to TryFallbackUnwindPlan() will return false.
- if (m_frames[cur_idx - 1]->reg_ctx_lldb_sp->TryFallbackUnwindPlan())
- {
- return AddOneMoreFrame (abi);
- }
+ if (prev_frame->reg_ctx_lldb_sp->TryFallbackUnwindPlan())
+ return GetOneMoreFrame (abi);
+
if (log)
- {
log->Printf("%*sFrame %d did not get PC for this frame, stopping stack walk",
cur_idx < 100 ? cur_idx : 100, "", cur_idx);
- }
- goto unwind_done;
+ return nullptr;
}
if (abi && !abi->CodeAddressIsValid (cursor_sp->start_pc))
{
// If the RegisterContextLLDB has a fallback UnwindPlan, it will switch to that and return
// true. Subsequent calls to TryFallbackUnwindPlan() will return false.
- if (m_frames[cur_idx - 1]->reg_ctx_lldb_sp->TryFallbackUnwindPlan())
- {
- return AddOneMoreFrame (abi);
- }
+ if (prev_frame->reg_ctx_lldb_sp->TryFallbackUnwindPlan())
+ return GetOneMoreFrame (abi);
+
if (log)
- {
log->Printf("%*sFrame %d did not get a valid PC, stopping stack walk",
cur_idx < 100 ? cur_idx : 100, "", cur_idx);
- }
- goto unwind_done;
+ return nullptr;
}
- if (!m_frames.empty())
+ // Infinite loop where the current cursor is the same as the previous one...
+ if (prev_frame->start_pc == cursor_sp->start_pc && prev_frame->cfa == cursor_sp->cfa)
{
- // Infinite loop where the current cursor is the same as the previous one...
- if (m_frames.back()->start_pc == cursor_sp->start_pc && m_frames.back()->cfa == cursor_sp->cfa)
- {
- if (log)
- log->Printf ("th%d pc of this frame is the same as the previous frame and CFAs for both frames are identical -- stopping unwind", m_thread.GetIndexID());
- goto unwind_done;
- }
+ if (log)
+ log->Printf ("th%d pc of this frame is the same as the previous frame and CFAs for both frames are identical -- stopping unwind", m_thread.GetIndexID());
+ return nullptr;
}
cursor_sp->reg_ctx_lldb_sp = reg_ctx_sp;
- m_frames.push_back (cursor_sp);
- return true;
-
-unwind_done:
- if (log)
+ return cursor_sp;
+}
+
+bool
+UnwindLLDB::AddOneMoreFrame (ABI *abi)
+{
+ Log *log(GetLogIfAllCategoriesSet (LIBLLDB_LOG_UNWIND));
+
+ // Frame zero is a little different
+ if (m_frames.empty())
+ return false;
+
+ // If we've already gotten to the end of the stack, don't bother to try again...
+ if (m_unwind_complete)
+ return false;
+
+ CursorSP new_frame = m_candidate_frame;
+ if (new_frame == nullptr)
+ new_frame = GetOneMoreFrame(abi);
+
+ if (new_frame == nullptr)
{
- log->Printf ("th%d Unwind of this thread is complete.", m_thread.GetIndexID());
+ if (log)
+ log->Printf ("th%d Unwind of this thread is complete.", m_thread.GetIndexID());
+ m_unwind_complete = true;
+ return false;
}
- m_unwind_complete = true;
- return false;
+
+ m_frames.push_back(new_frame);
+
+ // If we can get one more frame further then accept that we get back a correct frame.
+ m_candidate_frame = GetOneMoreFrame(abi);
+ if (m_candidate_frame)
+ return true;
+
+ // We can't go further from the frame returned by GetOneMore frame. Lets try to get a
+ // different frame with using the fallback unwind plan.
+ if (!m_frames[m_frames.size() - 2]->reg_ctx_lldb_sp->TryFallbackUnwindPlan())
+ {
+ // We don't have a valid fallback unwind plan. Accept the frame as it is. This is a
+ // valid situation when we are at the bottom of the stack.
+ return true;
+ }
+
+ // Remove the possibly incorrect frame from the frame list and try to add a different one with
+ // the newly selected fallback unwind plan.
+ m_frames.pop_back();
+ CursorSP new_frame_v2 = GetOneMoreFrame(abi);
+ if (new_frame_v2 == nullptr)
+ {
+ // We haven't got a new frame from the fallback unwind plan. Accept the frame from the
+ // original unwind plan. This is a valid situation when we are at the bottom of the stack.
+ m_frames.push_back(new_frame);
+ return true;
+ }
+
+ // Push the new frame to the list and try to continue from this frame. If we can get a new frame
+ // then accept it as the correct one.
+ m_frames.push_back(new_frame_v2);
+ m_candidate_frame = GetOneMoreFrame(abi);
+ if (m_candidate_frame)
+ return true;
+
+ // The new frame isn't helped in unwinding. Fall back to the original one as the default unwind
+ // plan is usually more reliable then the fallback one.
+ m_frames.pop_back();
+ m_frames.push_back(new_frame);
+ return true;
}
bool
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