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Add additional checks to the SavedLocationForRegister method 

where it is retrieving the Return Address register contents
on a target where that's a thing.  If we fail to get a valid
RA, we force a switch to the fallback unwind plan.  This patch
adds a sanity check for that fallback unwind plan -- it must
get a valid CFA for this frame in addition to being able to
retrieve the caller's PC -- and it correctly marks the unwind
rules as failing if the fallback unwind plan fails.

<rdar://problem/19010211> 

llvm-svn: 222301
This commit is contained in:
Jason Molenda 2014-11-19 02:29:52 +00:00
parent 5b9e48b4ce
commit 51a4511b72
1 changed files with 28 additions and 5 deletions
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33
lldb/source/Plugins/Process/Utility/RegisterContextLLDB.cpp
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@ -1267,12 +1267,30 @@ RegisterContextLLDB::SavedLocationForRegister (uint32_t lldb_regnum, lldb_privat
// Throw away the full unwindplan; install the arch default unwindplan
if (ForceSwitchToFallbackUnwindPlan())
{
// Now re-fetch the pc value we're searching for
RegisterNumber arch_default_pc_reg (m_thread, eRegisterKindGeneric, LLDB_REGNUM_GENERIC_PC);
// Update for the possibly new unwind plan
unwindplan_registerkind = m_full_unwind_plan_sp->GetRegisterKind ();
UnwindPlan::RowSP active_row = m_full_unwind_plan_sp->GetRowForFunctionOffset (m_current_offset);
if (arch_default_pc_reg.GetAsKind (unwindplan_registerkind) != LLDB_INVALID_REGNUM
&& active_row
&& active_row->GetRegisterInfo (arch_default_pc_reg.GetAsKind (unwindplan_registerkind), unwindplan_regloc))
// Sanity check: Verify that we can fetch a pc value and CFA value with this unwind plan
RegisterNumber arch_default_pc_reg (m_thread, eRegisterKindGeneric, LLDB_REGNUM_GENERIC_PC);
bool can_fetch_pc_value = false;
bool can_fetch_cfa = false;
addr_t cfa_value;
if (active_row)
{
if (arch_default_pc_reg.GetAsKind (unwindplan_registerkind) != LLDB_INVALID_REGNUM
&& active_row->GetRegisterInfo (arch_default_pc_reg.GetAsKind (unwindplan_registerkind), unwindplan_regloc))
{
can_fetch_pc_value = true;
}
if (ReadCFAValueForRow (unwindplan_registerkind, active_row, cfa_value))
{
can_fetch_cfa = true;
}
}
if (can_fetch_pc_value && can_fetch_cfa)
{
have_unwindplan_regloc = true;
}
@ -1281,6 +1299,11 @@ RegisterContextLLDB::SavedLocationForRegister (uint32_t lldb_regnum, lldb_privat
have_unwindplan_regloc = false;
}
}
else
{
// We were unable to fall back to another unwind plan
have_unwindplan_regloc = false;
}
}
}
}