tberghammer created this revision.
tberghammer added reviewers: ovyalov, jasonmolenda, clayborg.
tberghammer added a subscriber: lldb-commits.
Stack unwinding emulation: handle adjustment of FP
This change is improving the instruction emulation based unwinding to
handle when the frame pointer is adjusted (increment/decrement) after
it has been initialized. The situation can occur in the prologue of
some function where FP is adjusted before it is copied back to SP.
Example code (thumb, generated by gcc 4.8):
< +0>: push {r4, r7, lr}
< +2>: sub sp, #0x14
< +4>: add r7, sp, #0x0
...
<+50>: adds r7, #0x14 ; The CL fixes the handling of this instruction
<+52>: mov sp, r7 ; Previously unwinding from here was broken
<+54>: pop {r4, r7, pc}
http://reviews.llvm.org/D17295
Files:
source/Plugins/UnwindAssembly/InstEmulation/UnwindAssemblyInstEmulation.cpp
Index:
source/Plugins/UnwindAssembly/InstEmulation/UnwindAssemblyInstEmulation.cpp
===================================================================
--- source/Plugins/UnwindAssembly/InstEmulation/UnwindAssemblyInstEmulation.cpp
+++ source/Plugins/UnwindAssembly/InstEmulation/UnwindAssemblyInstEmulation.cpp
@@ -554,7 +554,6 @@
case EmulateInstruction::eContextTableBranchReadMemory:
case EmulateInstruction::eContextWriteRegisterRandomBits:
case EmulateInstruction::eContextWriteMemoryRandomBits:
- case EmulateInstruction::eContextArithmetic:
case EmulateInstruction::eContextAdvancePC:
case EmulateInstruction::eContextReturnFromException:
case EmulateInstruction::eContextPushRegisterOnStack:
@@ -573,6 +572,22 @@
// }
break;
+ case EmulateInstruction::eContextArithmetic:
+ {
+ // If we adjusted the current frame pointer by a constant then
adjust the CFA offset
+ // with the same amount.
+ lldb::RegisterKind kind = m_unwind_plan_ptr->GetRegisterKind();
+ if (m_fp_is_cfa && reg_info->kinds[kind] ==
m_cfa_reg_info.kinds[kind] &&
+ context.info_type ==
EmulateInstruction::eInfoTypeRegisterPlusOffset &&
+ context.info.RegisterPlusOffset.reg.kinds[kind] ==
m_cfa_reg_info.kinds[kind])
+ {
+ const int64_t offset =
context.info.RegisterPlusOffset.signed_offset;
+ m_curr_row->GetCFAValue().IncOffset(-1 * offset);
+ m_curr_row_modified = true;
+ }
+ }
+ break;
+
case EmulateInstruction::eContextAbsoluteBranchRegister:
case EmulateInstruction::eContextRelativeBranchImmediate:
{
Index: source/Plugins/UnwindAssembly/InstEmulation/UnwindAssemblyInstEmulation.cpp
===================================================================
--- source/Plugins/UnwindAssembly/InstEmulation/UnwindAssemblyInstEmulation.cpp
+++ source/Plugins/UnwindAssembly/InstEmulation/UnwindAssemblyInstEmulation.cpp
@@ -554,7 +554,6 @@
case EmulateInstruction::eContextTableBranchReadMemory:
case EmulateInstruction::eContextWriteRegisterRandomBits:
case EmulateInstruction::eContextWriteMemoryRandomBits:
- case EmulateInstruction::eContextArithmetic:
case EmulateInstruction::eContextAdvancePC:
case EmulateInstruction::eContextReturnFromException:
case EmulateInstruction::eContextPushRegisterOnStack:
@@ -573,6 +572,22 @@
// }
break;
+ case EmulateInstruction::eContextArithmetic:
+ {
+ // If we adjusted the current frame pointer by a constant then adjust the CFA offset
+ // with the same amount.
+ lldb::RegisterKind kind = m_unwind_plan_ptr->GetRegisterKind();
+ if (m_fp_is_cfa && reg_info->kinds[kind] == m_cfa_reg_info.kinds[kind] &&
+ context.info_type == EmulateInstruction::eInfoTypeRegisterPlusOffset &&
+ context.info.RegisterPlusOffset.reg.kinds[kind] == m_cfa_reg_info.kinds[kind])
+ {
+ const int64_t offset = context.info.RegisterPlusOffset.signed_offset;
+ m_curr_row->GetCFAValue().IncOffset(-1 * offset);
+ m_curr_row_modified = true;
+ }
+ }
+ break;
+
case EmulateInstruction::eContextAbsoluteBranchRegister:
case EmulateInstruction::eContextRelativeBranchImmediate:
{
_______________________________________________
lldb-commits mailing list
[email protected]
http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits
