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Enhance the eh_frame unwind instruction augmenter so that 

it will do the right thing on x86 routines with a mid-function
epilogue sequence (where the unwind rules need to be reinstalled
after the epilogue has completed).
<rdar://problem/19417410> 

llvm-svn: 225773
This commit is contained in:
Jason Molenda 2015-01-13 07:39:03 +00:00
parent 22e59748ef
commit 26cc634dbf
1 changed files with 46 additions and 6 deletions
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52
lldb/source/Plugins/UnwindAssembly/x86/UnwindAssembly-x86.cpp
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@ -818,10 +818,19 @@ AssemblyParse_x86::get_non_call_site_unwind_plan (UnwindPlan &unwind_plan)
row_updated = true;
}
// FIXME recognize the i386 picbase setup instruction sequence,
// 0x1f16: call 0x1f1b ; main + 11 at /private/tmp/a.c:3
// 0x1f1b: popl %eax
// and record the temporary stack movements if the CFA is not expressed in terms of ebp.
// call next instruction
// call 0
// => pop %ebx
// This is used in i386 programs to get the PIC base address for finding global data
else if (call_next_insn_pattern_p ())
{
current_sp_bytes_offset_from_cfa += m_wordsize;
if (row->GetCFARegister() == m_lldb_sp_regnum)
{
row->SetCFAOffset (current_sp_bytes_offset_from_cfa);
row_updated = true;
}
}
if (row_updated)
{
@ -884,12 +893,20 @@ AssemblyParse_x86::augment_unwind_plan_from_call_site (AddressRange& func, Unwin
if (cfa_reg != m_lldb_sp_regnum || first_row->GetCFAOffset() != m_wordsize)
return false;
UnwindPlan::RowSP original_last_row = unwind_plan.GetRowForFunctionOffset (-1);
Target *target = m_exe_ctx.GetTargetPtr();
m_cur_insn = func.GetBaseAddress();
uint64_t offset = 0;
int row_id = 1;
bool unwind_plan_updated = false;
UnwindPlan::RowSP row(new UnwindPlan::Row(*first_row));
// After a mid-function epilogue we will need to re-insert the original unwind rules
// so unwinds work for the remainder of the function. These aren't common with clang/gcc
// on x86 but it is possible.
bool reinstate_unwind_state = false;
while (func.ContainsFileAddress (m_cur_insn))
{
int insn_len;
@ -912,6 +929,23 @@ AssemblyParse_x86::augment_unwind_plan_from_call_site (AddressRange& func, Unwin
offset += insn_len;
m_cur_insn.SetOffset(m_cur_insn.GetOffset() + insn_len);
if (reinstate_unwind_state)
{
// that was the last instruction of this function
if (func.ContainsFileAddress (m_cur_insn) == false)
continue;
UnwindPlan::RowSP new_row(new UnwindPlan::Row());
*new_row = *original_last_row;
new_row->SetOffset (offset);
unwind_plan.AppendRow (new_row);
row.reset (new UnwindPlan::Row());
*row = *new_row;
reinstate_unwind_state = false;
unwind_plan_updated = true;
continue;
}
// 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)
@ -1016,6 +1050,11 @@ AssemblyParse_x86::augment_unwind_plan_from_call_site (AddressRange& func, Unwin
unwind_plan_updated = true;
continue;
}
if (ret_pattern_p ())
{
reinstate_unwind_state = true;
continue;
}
}
else if (cfa_reg == m_lldb_fp_regnum)
{
@ -1037,6 +1076,7 @@ AssemblyParse_x86::augment_unwind_plan_from_call_site (AddressRange& func, Unwin
UnwindPlan::RowSP new_row(new UnwindPlan::Row(*row));
unwind_plan.InsertRow (new_row);
unwind_plan_updated = true;
reinstate_unwind_state = true;
continue;
}
}
@ -1260,8 +1300,8 @@ UnwindAssembly_x86::AugmentUnwindPlanFromCallSite (AddressRange& func, Thread& t
}
// It looks like the prologue is described. Now check to see if the epilogue has the same
// unwind state.
// It looks like the prologue is described.
// Is the epilogue described? If it is, no need to do any augmentation.
if (first_row != last_row && first_row->GetOffset() != last_row->GetOffset())
{