Hoist the RegisterNumber class out of RegisterContextLLDB and make
it more generally available.
Add checks to UnwindAssembly_x86::AugmentUnwindPlanFromCallSite() so
that it won't try to augment an UnwindPlan that already describes
the function epilogue.
Add a test case for backtracing out of _sigtramp on Darwin systems.
This could probably be adapted to test the same thing on linux/bsd but
the function names of sigtramp and kill are probably platform
specific and I'm not sure what they should be.
llvm-svn: 225578
diff --git a/lldb/source/Plugins/UnwindAssembly/x86/UnwindAssembly-x86.cpp b/lldb/source/Plugins/UnwindAssembly/x86/UnwindAssembly-x86.cpp
index 730784b..af70858 100644
--- a/lldb/source/Plugins/UnwindAssembly/x86/UnwindAssembly-x86.cpp
+++ b/lldb/source/Plugins/UnwindAssembly/x86/UnwindAssembly-x86.cpp
@@ -23,6 +23,7 @@
#include "lldb/Target/Thread.h"
#include "lldb/Target/Target.h"
#include "lldb/Target/UnwindAssembly.h"
+#include "lldb/Utility/RegisterNumber.h"
using namespace lldb;
using namespace lldb_private;
@@ -955,7 +956,9 @@
// If we already have one row for this instruction, we can continue.
while (row_id < unwind_plan.GetRowCount()
&& unwind_plan.GetRowAtIndex (row_id)->GetOffset() <= offset)
+ {
row_id++;
+ }
UnwindPlan::RowSP original_row = unwind_plan.GetRowAtIndex (row_id - 1);
if (original_row->GetOffset() == offset)
{
@@ -1262,9 +1265,71 @@
bool
UnwindAssembly_x86::AugmentUnwindPlanFromCallSite (AddressRange& func, Thread& thread, UnwindPlan& unwind_plan)
{
- ExecutionContext exe_ctx (thread.shared_from_this());
- AssemblyParse_x86 asm_parse(exe_ctx, m_cpu, m_arch, func);
- return asm_parse.augment_unwind_plan_from_call_site (func, unwind_plan);
+ bool do_augment_unwindplan = true;
+
+ UnwindPlan::RowSP first_row = unwind_plan.GetRowForFunctionOffset (0);
+ UnwindPlan::RowSP last_row = unwind_plan.GetRowForFunctionOffset (-1);
+
+ // If the UnwindPlan correctly describes the prologue and the epilogue, then
+ // we shouldn't do any augmentation (and risk messing up correct unwind instructions)
+
+ // See if the first row (which should be the register state on function entry)
+ // and the last row (which should be the register state on function exit) match.
+
+ if (first_row != last_row && first_row->GetOffset() != last_row->GetOffset())
+ {
+ RegisterNumber sp_regnum (thread, eRegisterKindGeneric, LLDB_REGNUM_GENERIC_SP);
+
+ // The first & last row have the same CFA register
+ // and the same CFA offset value
+ // and the CFA register is esp/rsp (the stack pointer).
+
+ // We're checking that both of them have an unwind rule like "CFA=esp+4" or CFA+rsp+8".
+
+ if (first_row->GetCFAType() == last_row->GetCFAType()
+ && first_row->GetCFAType() == UnwindPlan::Row::CFAType::CFAIsRegisterPlusOffset
+ && first_row->GetCFARegister() == last_row->GetCFARegister()
+ && first_row->GetCFAOffset() == last_row->GetCFAOffset()
+ && RegisterNumber (thread, unwind_plan.GetRegisterKind(), first_row->GetCFARegister()) == sp_regnum)
+ {
+ RegisterNumber pc_regnum (thread, eRegisterKindGeneric, LLDB_REGNUM_GENERIC_PC);
+
+ // Get the register locations for eip/rip from the first & last rows.
+ // Are they both CFA plus an offset? Is it the same offset?
+
+ UnwindPlan::Row::RegisterLocation first_row_pc_loc;
+ UnwindPlan::Row::RegisterLocation last_row_pc_loc;
+ if (first_row->GetRegisterInfo (pc_regnum.GetAsKind (unwind_plan.GetRegisterKind()), first_row_pc_loc)
+ && last_row->GetRegisterInfo (pc_regnum.GetAsKind (unwind_plan.GetRegisterKind()), last_row_pc_loc))
+ {
+ if (first_row_pc_loc.IsAtCFAPlusOffset()
+ && last_row_pc_loc.IsAtCFAPlusOffset()
+ && first_row_pc_loc.GetOffset() == last_row_pc_loc.GetOffset())
+ {
+
+ // One last sanity check: Is the unwind rule for getting the caller pc value
+ // "deref the CFA-4" or "deref the CFA-8"?
+
+ // If so, we have an UnwindPlan that already describes the epilogue and we don't need
+ // to modify it at all.
+
+ if (first_row_pc_loc.GetOffset() == -4 || first_row_pc_loc.GetOffset() == -8)
+ {
+ do_augment_unwindplan = false;
+ }
+ }
+ }
+ }
+ }
+
+ if (do_augment_unwindplan)
+ {
+ ExecutionContext exe_ctx (thread.shared_from_this());
+ AssemblyParse_x86 asm_parse(exe_ctx, m_cpu, m_arch, func);
+ return asm_parse.augment_unwind_plan_from_call_site (func, unwind_plan);
+ }
+
+ return false;
}
bool