[lldb-dev] debugging ios-simul speed issue

[Carlo Kok]

Op 27-3-2013 23:28, Greg Clayton schreef:
> You will need to sample the application that is running LLDB (MSVC?) to see what it is doing. This delay happens _after_ a read and before the next write, so the program is up to something in between there.
>

I did; one of the biggest slowdowns seems to be due to my "exception 
breakpoint":

self->m_target.BreakpointCreateForException(lldb::eLanguageTypeObjC, 
false, true);

When set, after libresolv.dylib got loaded, it loads the DWARF symbols 
for all referenced libraries then tries to find "objc_exception_throw",

Setting a BP in :
void
Breakpoint::ResolveBreakpointInModules (ModuleList &module_list)
{
     if (m_resolver_sp)
         m_resolver_sp->ResolveBreakpointInModules(*m_filter_sp, 
module_list);
}

the "ResolveBerakpointInModules" takes 6 seconds (for 120 modules)

If i press pause i get a callstack like:
msvcr100d.dll!unaligned_memcmp(const unsigned char * bLHS, const 
unsigned char * bRHS, unsigned int siz)  + 0xcf bytes	C
msvcr100d.dll!memcmp(const void * lhs, const void * rhs, unsigned int 
siz)  + 0x19c bytes	C
llvm::StringRef::compareMemory(const char * Lhs, const char * Rhs, 
unsigned int Length)  Line 65 + 0x11 bytes	C++
llvm::StringRef::equals(llvm::StringRef RHS)  Line 131 + 0x1e bytes	C++
llvm::operator==(llvm::StringRef LHS, llvm::StringRef RHS)  Line 516	C++
llvm::StringMapImpl::LookupBucketFor(llvm::StringRef Name)  Line 97 + 
0x29 bytes	C++
llvm::StringMap<char const 
*,llvm::BumpPtrAllocator>::GetOrCreateValue<char const 
*>(llvm::StringRef Key, const char * Val)  Line 350 + 0x10 bytes	C++
Pool::GetConstCStringWithLength(const char * cstr, int cstr_len)  Line 
96 + 0x15 bytes	C++
Pool::GetConstCString(const char * cstr)  Line 85 + 0x19 bytes	C++
lldb_private::ConstString::ConstString(const char * cstr)  Line 212 + 
0x1e bytes	C++
ObjectFileMachO::ParseSymtab(bool minimize)  Line 2922 + 0x12 bytes	C++
ObjectFileMachO::GetSymtab()  Line 744	C++
SymbolFileSymtab::CalculateAbilities()  Line 89 + 0x15 bytes	C++
lldb_private::SymbolFile::GetAbilities()  Line 96 + 0xf bytes	C++
lldb_private::SymbolFile::FindPlugin(lldb_private::ObjectFile * 
obj_file)  Line 39 + 0xf bytes	C++
lldb_private::SymbolVendor::AddSymbolFileRepresentation(const 
std::tr1::shared_ptr<lldb_private::ObjectFile> & objfile_sp)  Line 99 
+ 0xe bytes	C++
lldb_private::SymbolVendor::FindPlugin(const 
std::tr1::shared_ptr<lldb_private::Module> & module_sp, 
lldb_private::Stream * feedback_strm)  Line 63 + 0x1f bytes	C++
lldb_private::Module::GetSymbolVendor(bool can_create, 
lldb_private::Stream * feedback_strm)  Line 780 + 0x19 bytes	C++
lldb_private::Module::FindFunctions(const lldb_private::ConstString & 
name, const lldb_private::ClangNamespaceDecl * namespace_decl, unsigned 
int name_type_mask, bool include_symbols, bool include_inlines, bool 
append, lldb_private::SymbolContextList & sc_list)  Line 589 + 0x13 
bytes	C++
lldb_private::BreakpointResolverName::SearchCallback(lldb_private::SearchFilter 
& filter, lldb_private::SymbolContext & context, lldb_private::Address * 
addr, bool containing)  Line 179 + 0x38 bytes	C++
lldb_private::LanguageRuntime::ExceptionBreakpointResolver::SearchCallback(lldb_private::SearchFilter 
& filter, lldb_private::SymbolContext & context, lldb_private::Address * 
addr, bool containing)  Line 153 + 0x2e bytes	C++
lldb_private::SearchFilter::DoModuleIteration(const 
lldb_private::SymbolContext & context, lldb_private::Searcher & 
searcher)  Line 198 + 0x1b bytes	C++
lldb_private::SearchFilter::DoModuleIteration(const 
std::tr1::shared_ptr<lldb_private::Module> & module_sp, 
lldb_private::Searcher & searcher)  Line 185 + 0x10 bytes	C++
lldb_private::SearchFilter::SearchInModuleList(lldb_private::Searcher & 
searcher, lldb_private::ModuleList & modules)  Line 173 + 0x13 bytes	C++
lldb_private::BreakpointResolver::ResolveBreakpointInModules(lldb_private::SearchFilter 
& filter, lldb_private::ModuleList & modules)  Line 53 + 0x17 bytes	C++
lldb_private::Breakpoint::ResolveBreakpointInModules(lldb_private::ModuleList 
& module_list)  Line 341 + 0x2d bytes	C++
lldb_private::Breakpoint::ModulesChanged(lldb_private::ModuleList & 
module_list, bool load, bool delete_locations)  Line 420	C++
lldb_private::BreakpointList::UpdateBreakpoints(lldb_private::ModuleList 
& module_list, bool added)  Line 213 + 0x21 bytes	C++
lldb_private::Target::ModulesDidLoad(lldb_private::ModuleList & 
module_list)  Line 1136	C++
DynamicLoaderMacOSXDYLD::AddModulesUsingImageInfos(std::vector<DynamicLoaderMacOSXDYLD::DYLDImageInfo,std::allocator<DynamicLoaderMacOSXDYLD::DYLDImageInfo> 
 > & image_infos)  Line 938	C++
DynamicLoaderMacOSXDYLD::AddModulesUsingImageInfosAddress(unsigned 
__int64 image_infos_addr, unsigned int image_infos_count)  Line 836 + 
0xc bytes	C++
DynamicLoaderMacOSXDYLD::InitializeFromAllImageInfos()  Line 1109 + 
0x23 bytes	C++
DynamicLoaderMacOSXDYLD::NotifyBreakpointHit(void * baton, 
lldb_private::StoppointCallbackContext * context, unsigned __int64 
break_id, unsigned __int64 break_loc_id)  Line 641 + 0x8 bytes	C++
lldb_private::BreakpointOptions::InvokeCallback(lldb_private::StoppointCallbackContext 
* context, unsigned __int64 break_id, unsigned __int64 break_loc_id) 
Line 150 + 0x4c bytes	C++
lldb_private::Breakpoint::InvokeCallback(lldb_private::StoppointCallbackContext 
* context, int bp_loc_id)  Line 322	C++
lldb_private::BreakpointLocation::InvokeCallback(lldb_private::StoppointCallbackContext 
* context)  Line 208	C++
lldb_private::BreakpointLocation::ShouldStop(lldb_private::StoppointCallbackContext 
* context)  Line 340 + 0xc bytes	C++
lldb_private::BreakpointLocationCollection::ShouldStop(lldb_private::StoppointCallbackContext 
* context)  Line 144 + 0x2d bytes	C++
lldb_private::BreakpointSite::ShouldStop(lldb_private::StoppointCallbackContext 
* context)  Line 66	C++
lldb_private::StopInfoBreakpoint::ShouldStopSynchronous(lldb_private::Event 
* event_ptr)  Line 163 + 0x2a bytes	C++
lldb_private::Thread::ShouldStop(lldb_private::Event * event_ptr)  Line 
602 + 0x34 bytes	C++


(top part varies, but it always has GetSymtab in it.)


I haven't found a sampling profiler that works yet so I don't know how 
to get much more info from this yet. Is there any chance this is long 
optimized and I'm just behind on revisions on the Windows branch?