Author: tberghammer Date: Fri Jul 3 04:30:22 2015 New Revision: 241334 URL: http://llvm.org/viewvc/llvm-project?rev=241334&view=rev Log: Enable usage of eh_frame based unwind plan as a fallback
Previously if the instruction emulation based unwind plan failed then we fall back to the arch default unwind plan. Change it to fall back to the eh_frame based one even on non call sites if we have eh_frame as that one tend to be more reliable. Differential revision: http://reviews.llvm.org/D10902 Modified: lldb/trunk/source/Plugins/Process/Utility/RegisterContextLLDB.cpp Modified: lldb/trunk/source/Plugins/Process/Utility/RegisterContextLLDB.cpp URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/source/Plugins/Process/Utility/RegisterContextLLDB.cpp?rev=241334&r1=241333&r2=241334&view=diff ============================================================================== --- lldb/trunk/source/Plugins/Process/Utility/RegisterContextLLDB.cpp (original) +++ lldb/trunk/source/Plugins/Process/Utility/RegisterContextLLDB.cpp Fri Jul 3 04:30:22 2015 @@ -855,12 +855,26 @@ RegisterContextLLDB::GetFullUnwindPlanFo { if (unwind_plan_sp->GetSourcedFromCompiler() == eLazyBoolNo) { - // We probably have an UnwindPlan created by inspecting assembly instructions, and we probably - // don't have any eh_frame instructions available. - // The assembly profilers work really well with compiler-generated functions but hand-written - // assembly can be problematic. We'll set the architecture default UnwindPlan as our fallback - // UnwindPlan in case this doesn't work out when we try to unwind. - m_fallback_unwind_plan_sp = arch_default_unwind_plan_sp; + // We probably have an UnwindPlan created by inspecting assembly instructions. The + // assembly profilers work really well with compiler-generated functions but hand- + // written assembly can be problematic. We set the eh_frame based unwind plan as our + // fallback unwind plan if instruction emulation doesn't work out even for non call + // sites if it is available and use the architecture default unwind plan if it is + // not available. The eh_frame unwind plan is more reliable even on non call sites + // then the architecture default plan and for hand written assembly code it is often + // written in a way that it valid at all location what helps in the most common + // cases when the instruction emulation fails. + UnwindPlanSP eh_frame_unwind_plan = func_unwinders_sp->GetEHFrameUnwindPlan (process->GetTarget(), m_current_offset_backed_up_one); + if (eh_frame_unwind_plan && + eh_frame_unwind_plan.get() != unwind_plan_sp.get() && + eh_frame_unwind_plan->GetSourceName() != unwind_plan_sp->GetSourceName()) + { + m_fallback_unwind_plan_sp = eh_frame_unwind_plan; + } + else + { + m_fallback_unwind_plan_sp = arch_default_unwind_plan_sp; + } } UnwindLogMsgVerbose ("frame uses %s for full UnwindPlan", unwind_plan_sp->GetSourceName().GetCString()); return unwind_plan_sp; @@ -887,12 +901,25 @@ RegisterContextLLDB::GetFullUnwindPlanFo } if (unwind_plan_sp && unwind_plan_sp->GetSourcedFromCompiler() == eLazyBoolNo) { - // We probably have an UnwindPlan created by inspecting assembly instructions, and we probably - // don't have any eh_frame instructions available. - // The assembly profilers work really well with compiler-generated functions but hand-written - // assembly can be problematic. We'll set the architecture default UnwindPlan as our fallback - // UnwindPlan in case this doesn't work out when we try to unwind. - m_fallback_unwind_plan_sp = arch_default_unwind_plan_sp; + // We probably have an UnwindPlan created by inspecting assembly instructions. The assembly + // profilers work really well with compiler-generated functions but hand- written assembly + // can be problematic. We set the eh_frame based unwind plan as our fallback unwind plan if + // instruction emulation doesn't work out even for non call sites if it is available and use + // the architecture default unwind plan if it is not available. The eh_frame unwind plan is + // more reliable even on non call sites then the architecture default plan and for hand + // written assembly code it is often written in a way that it valid at all location what + // helps in the most common cases when the instruction emulation fails. + UnwindPlanSP eh_frame_unwind_plan = func_unwinders_sp->GetEHFrameUnwindPlan (process->GetTarget(), m_current_offset_backed_up_one); + if (eh_frame_unwind_plan && + eh_frame_unwind_plan.get() != unwind_plan_sp.get() && + eh_frame_unwind_plan->GetSourceName() != unwind_plan_sp->GetSourceName()) + { + m_fallback_unwind_plan_sp = eh_frame_unwind_plan; + } + else + { + m_fallback_unwind_plan_sp = arch_default_unwind_plan_sp; + } } if (IsUnwindPlanValidForCurrentPC(unwind_plan_sp, valid_offset)) _______________________________________________ lldb-commits mailing list lldb-commits@cs.uiuc.edu http://lists.cs.uiuc.edu/mailman/listinfo/lldb-commits