maxjhandsome
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Releases Wiki Activity

Add a new 'eRegisterInLiveRegisterContext' RegisterLocation to track 

a register value that is live in the stack frame 0 register context.

Fixes a problem where retrieving a register value on stack frame #n
would involved O(n!) stack frame checks.  This could be very slow on
a deep stack when retrieving register values that had not been
modified/saved by any of the stack frames.  Not common, but annoying
when it was hit.

<rdar://problem/19010211> 

llvm-svn: 223843
This commit is contained in:
Jason Molenda 2014-12-09 22:28:10 +00:00
parent 00de22f963
commit ce19fe3f38
3 changed files with 44 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

42
lldb/source/Plugins/Process/Utility/RegisterContextLLDB.cpp
View File

@ -958,6 +958,16 @@ RegisterContextLLDB::ReadRegisterValueFromRegisterLocation (lldb_private::Unwind
switch (regloc.type)
{
case UnwindLLDB::RegisterLocation::eRegisterInLiveRegisterContext:
{
const RegisterInfo *other_reg_info = GetRegisterInfoAtIndex(regloc.location.register_number);
if (!other_reg_info)
return false;
success = m_thread.GetRegisterContext()->ReadRegister (other_reg_info, value);
}
break;
case UnwindLLDB::RegisterLocation::eRegisterInRegister:
{
const RegisterInfo *other_reg_info = GetRegisterInfoAtIndex(regloc.location.register_number);
@ -1012,6 +1022,12 @@ RegisterContextLLDB::WriteRegisterValueToRegisterLocation (lldb_private::UnwindL
switch (regloc.type)
{
case UnwindLLDB::RegisterLocation::eRegisterInLiveRegisterContext:
{
const RegisterInfo *other_reg_info = GetRegisterInfoAtIndex(regloc.location.register_number);
success = m_thread.GetRegisterContext()->WriteRegister (other_reg_info, value);
}
break;
case UnwindLLDB::RegisterLocation::eRegisterInRegister:
{
const RegisterInfo *other_reg_info = GetRegisterInfoAtIndex(regloc.location.register_number);
@ -1232,7 +1248,7 @@ RegisterContextLLDB::SavedLocationForRegister (uint32_t lldb_regnum, lldb_privat
if (return_address_reg.GetAsKind (eRegisterKindLLDB) != LLDB_INVALID_REGNUM)
{
lldb_private::UnwindLLDB::RegisterLocation new_regloc;
new_regloc.type = UnwindLLDB::RegisterLocation::eRegisterInRegister;
new_regloc.type = UnwindLLDB::RegisterLocation::eRegisterInLiveRegisterContext;
new_regloc.location.register_number = return_address_reg.GetAsKind (eRegisterKindLLDB);
m_registers[regnum.GetAsKind (eRegisterKindLLDB)] = new_regloc;
regloc = new_regloc;
@ -1334,7 +1350,7 @@ RegisterContextLLDB::SavedLocationForRegister (uint32_t lldb_regnum, lldb_privat
{
// This is frame 0 - we should return the actual live register context value
lldb_private::UnwindLLDB::RegisterLocation new_regloc;
new_regloc.type = UnwindLLDB::RegisterLocation::eRegisterInRegister;
new_regloc.type = UnwindLLDB::RegisterLocation::eRegisterInLiveRegisterContext;
new_regloc.location.register_number = regnum.GetAsKind (eRegisterKindLLDB);
m_registers[regnum.GetAsKind (eRegisterKindLLDB)] = new_regloc;
regloc = new_regloc;
@ -1343,8 +1359,18 @@ RegisterContextLLDB::SavedLocationForRegister (uint32_t lldb_regnum, lldb_privat
return UnwindLLDB::RegisterSearchResult::eRegisterFound;
}
else
UnwindLogMsg ("could not supply caller's %s (%d) location",
regnum.GetName(), regnum.GetAsKind (eRegisterKindLLDB));
{
std::string unwindplan_name ("");
if (m_full_unwind_plan_sp)
{
unwindplan_name += "via '";
unwindplan_name += m_full_unwind_plan_sp->GetSourceName().AsCString();
unwindplan_name += "'";
}
UnwindLogMsg ("no save location for %s (%d) %s",
regnum.GetName(), regnum.GetAsKind (eRegisterKindLLDB),
unwindplan_name.c_str());
}
return UnwindLLDB::RegisterSearchResult::eRegisterNotFound;
}
@ -1354,7 +1380,7 @@ RegisterContextLLDB::SavedLocationForRegister (uint32_t lldb_regnum, lldb_privat
lldb_private::UnwindLLDB::RegisterLocation new_regloc;
new_regloc.type = UnwindLLDB::RegisterLocation::eRegisterNotSaved;
m_registers[regnum.GetAsKind (eRegisterKindLLDB)] = new_regloc;
UnwindLogMsg ("could not supply caller's %s (%d) location",
UnwindLogMsg ("save location for %s (%d) is unspecified, continue searching",
regnum.GetName(), regnum.GetAsKind (eRegisterKindLLDB));
return UnwindLLDB::RegisterSearchResult::eRegisterNotFound;
}
@ -1363,7 +1389,7 @@ RegisterContextLLDB::SavedLocationForRegister (uint32_t lldb_regnum, lldb_privat
{
if (IsFrameZero ())
{
UnwindLogMsg ("could not supply caller's %s (%d) location",
UnwindLogMsg ("could not supply caller's %s (%d) location, IsSame",
regnum.GetName(), regnum.GetAsKind (eRegisterKindLLDB));
return UnwindLLDB::RegisterSearchResult::eRegisterNotFound;
}
@ -1403,7 +1429,7 @@ RegisterContextLLDB::SavedLocationForRegister (uint32_t lldb_regnum, lldb_privat
RegisterNumber row_regnum (m_thread, unwindplan_registerkind, unwindplan_regnum);
if (row_regnum.GetAsKind (eRegisterKindLLDB) == LLDB_INVALID_REGNUM)
{
UnwindLogMsg ("could not supply caller's %s (%d) location",
UnwindLogMsg ("could not supply caller's %s (%d) location - was saved in another reg but couldn't convert that regnum",
regnum.GetName(), regnum.GetAsKind (eRegisterKindLLDB));
return UnwindLLDB::RegisterSearchResult::eRegisterNotFound;
}
@ -1454,7 +1480,7 @@ RegisterContextLLDB::SavedLocationForRegister (uint32_t lldb_regnum, lldb_privat
return UnwindLLDB::RegisterSearchResult::eRegisterNotFound;
}
UnwindLogMsg ("could not supply caller's %s (%d) location",
UnwindLogMsg ("no save location for %s (%d) in this stack frame",
regnum.GetName(), regnum.GetAsKind (eRegisterKindLLDB));
// FIXME UnwindPlan::Row types atDWARFExpression and isDWARFExpression are unsupported.

8
lldb/source/Plugins/Process/Utility/UnwindLLDB.cpp
View File

@ -384,6 +384,14 @@ UnwindLLDB::SearchForSavedLocationForRegister (uint32_t lldb_regnum, lldb_privat
UnwindLLDB::RegisterSearchResult result;
result = m_frames[frame_num]->reg_ctx_lldb_sp->SavedLocationForRegister (lldb_regnum, regloc);
// We descended down to the live register context aka stack frame 0 and are reading the value
// out of a live register.
if (result == UnwindLLDB::RegisterSearchResult::eRegisterFound
&& regloc.type == UnwindLLDB::RegisterLocation::eRegisterInLiveRegisterContext)
{
return true;
}
// If we have unwind instructions saying that register N is saved in register M in the middle of
// the stack (and N can equal M here, meaning the register was not used in this function), then
// change the register number we're looking for to M and keep looking for a concrete location

3
lldb/source/Plugins/Process/Utility/UnwindLLDB.h
View File

@ -48,7 +48,8 @@ protected:
eRegisterSavedAtMemoryLocation, // register is saved at a specific word of target mem (target_memory_location)
eRegisterInRegister, // register is available in a (possible other) register (register_number)
eRegisterSavedAtHostMemoryLocation, // register is saved at a word in lldb's address space
eRegisterValueInferred // register val was computed (and is in inferred_value)
eRegisterValueInferred, // register val was computed (and is in inferred_value)
eRegisterInLiveRegisterContext // register value is in a live (stack frame #0) register
};
int type;
union