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 CursorSP; std::vector 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 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 @@ -154,21 +153,20 @@ 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()) @@ -176,31 +174,25 @@ // 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)) { @@ -219,24 +211,19 @@ || 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); - } } } } @@ -244,54 +231,103 @@ { // 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