Improve check for ASAN callbacks

[tberghammer]

Summary

Improve check for ASAN callbacks

The ASAN callbacks are public symbols so we can search for them
with reading only the symbol table (not the debug info). Whit this
change the attach time for a big executable with debug symbols
decreased by a factor of ~4 on Linux.

[kubamracek]

Nice improvement. Looks good to me, but please let Jason or Enrico review this as well.

[tberghammer]

Friendly ping

Note: The ~4x speed improvement in attach time will be spent in the later stage of the debugging if we have to parse the full dwarf info

[jingham]

Did you try just turning "include_inlines" to false? If we are just looking up a name and not looking for inlines we shouldn't have to go grubbing in the debug information.

[tberghammer]

I tried it, but it isn't help. Module::FindFunctions always parses the dwraf info for some reason (I haven't investigated why). Also I think "__asan_get_alloc_stack" is the name of a symbol so FindSymbol is the right function to call here.

[tberghammer]

Friendly ping

[sas]

Looks pretty good.

source/Plugins/InstrumentationRuntime/AddressSanitizer/AddressSanitizerRuntime.cpp

 
 AddressSanitizerRuntime::~AddressSanitizerRuntime()
 {
     Deactivate();
 }
 
 bool ModuleContainsASanRuntime(Module * module)
 {
-    SymbolContextList sc_list;
-    const bool include_symbols = true;
-    const bool append = true;
-    const bool include_inlines = true;
-    
-    size_t num_matches = module->FindFunctions(ConstString("__asan_get_alloc_stack"), NULL, eFunctionNameTypeAuto, include_symbols, include_inlines, append, sc_list);
-    
-    return num_matches > 0;
+    const Symbol* symbol = module->FindFirstSymbolWithNameAndType(
+            ConstString("__asan_get_alloc_stack"),
+            lldb::eSymbolTypeAny);
+    return symbol != nullptr;
 }
 
 void
 AddressSanitizerRuntime::ModulesDidLoad(lldb_private::ModuleList &module_list)
 {
     if (IsActive())
         return;
     

source/Plugins/MemoryHistory/asan/MemoryHistoryASan.cpp

 using namespace lldb;
 using namespace lldb_private;
 
 MemoryHistorySP
 MemoryHistoryASan::CreateInstance (const ProcessSP &process_sp)
 {
     if (!process_sp.get())
         return NULL;
-    
     Target & target = process_sp->GetTarget();
-    
-    bool found_asan_runtime = false;
-    
     const ModuleList &target_modules = target.GetImages();
     Mutex::Locker modules_locker(target_modules.GetMutex());
     const size_t num_modules = target_modules.GetSize();
     for (size_t i = 0; i < num_modules; ++i)
     {
         Module *module_pointer = target_modules.GetModulePointerAtIndexUnlocked(i);
-        
-        SymbolContextList sc_list;
-        const bool include_symbols = true;
-        const bool append = true;
-        const bool include_inlines = true;
-
-        size_t num_matches = module_pointer->FindFunctions(ConstString("__asan_get_alloc_stack"), NULL, eFunctionNameTypeAuto, include_symbols, include_inlines, append, sc_list);
-        
-        if (num_matches)
-        {
-            found_asan_runtime = true;
-            break;
-        }
+        const Symbol* symbol = module_pointer->FindFirstSymbolWithNameAndType(
+                ConstString("__asan_get_alloc_stack"),
+                lldb::eSymbolTypeAny);
+        if (symbol != nullptr)
+            return MemoryHistorySP(new MemoryHistoryASan(process_sp));        
     }
-    
-    if (! found_asan_runtime)
-        return MemoryHistorySP();
-
-    return MemoryHistorySP(new MemoryHistoryASan(process_sp));
 }
 
 void
 MemoryHistoryASan::Initialize()
 {
     PluginManager::RegisterPlugin (GetPluginNameStatic(),
                                    "ASan memory history provider.",
                                    CreateInstance);