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Add "support" for DW_CFA_GNU_args_size to the unwinder 

Summary:
This adds the knowledge of the DW_CFA_GNU_args_size instruction to the eh_frame parsing code.
Right now it is ignored as I am unsure how is it supposed to be handled, but now we are at least
able to parse the rest of the FDE containing this instruction.

I also add a fix for a bug which was exposed by this instruction. Namely, a mismatched sequence
of remember/restore instructions in the input could cause us to pop an empty stack and crash. Now
we just log the error and ignore the offending instruction.

Reviewers: jasonmolenda

Subscribers: lldb-commits

Differential Revision: http://reviews.llvm.org/D22266

llvm-svn: 275260
This commit is contained in:
Pavel Labath 2016-07-13 10:55:24 +00:00
parent 10e9e59898
commit 1ee89eb8d9
1 changed files with 20 additions and 0 deletions
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20
lldb/source/Symbol/DWARFCallFrameInfo.cpp
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@ -408,6 +408,7 @@ DWARFCallFrameInfo::GetFDEIndex ()
bool
DWARFCallFrameInfo::FDEToUnwindPlan (dw_offset_t dwarf_offset, Address startaddr, UnwindPlan& unwind_plan)
{
Log *log = GetLogIfAllCategoriesSet(LIBLLDB_LOG_UNWIND);
lldb::offset_t offset = dwarf_offset;
lldb::offset_t current_entry = offset;
@ -648,6 +649,15 @@ DWARFCallFrameInfo::FDEToUnwindPlan (dw_offset_t dwarf_offset, Address startaddr
// the stack and place them in the current row. (This operation is
// useful for compilers that move epilogue code into the body of a
// function.)
if (stack.empty())
{
if (log)
log->Printf(
"DWARFCallFrameInfo::%s(dwarf_offset: %" PRIx32 ", startaddr: %" PRIx64
" encountered DW_CFA_restore_state but state stack is empty. Corrupt unwind info?",
__FUNCTION__, dwarf_offset, startaddr.GetFileAddress());
break;
}
lldb::addr_t offset = row->GetOffset ();
row = stack.back ();
stack.pop_back ();
@ -655,6 +665,16 @@ DWARFCallFrameInfo::FDEToUnwindPlan (dw_offset_t dwarf_offset, Address startaddr
break;
}
case DW_CFA_GNU_args_size: // 0x2e
{
// The DW_CFA_GNU_args_size instruction takes an unsigned LEB128 operand
// representing an argument size. This instruction specifies the total of
// the size of the arguments which have been pushed onto the stack.
// TODO: Figure out how we should handle this.
m_cfi_data.GetULEB128(&offset);
}
case DW_CFA_val_offset : // 0x14
case DW_CFA_val_offset_sf : // 0x15
default: