[XRay] Small ObjID fix

Author: sebastiankreutzer

compiler-rt/lib/xray/xray_init.cpp

@@ -56,7 +56,7 @@ SpinMutex XRayInstrMapMutex;
 //  Contains maps for the main executable as well as DSOs.
 // std::vector<XRaySledMap> XRayInstrMaps;
 XRaySledMap *XRayInstrMaps;
-atomic_uint32_t XRayNumObjects;
+atomic_uint32_t XRayNumObjects{0};
 
 // Global flag to determine whether the flags have been initialized.
 atomic_uint8_t XRayFlagsInitialized{0};

compiler-rt/lib/xray/xray_interface.cpp

@@ -658,7 +658,7 @@ size_t __xray_max_function_id() XRAY_NEVER_INSTRUMENT {
 
 size_t __xray_max_function_id_in_object(int32_t ObjId) XRAY_NEVER_INSTRUMENT {
   SpinMutexLock Guard(&XRayInstrMapMutex);
-  if (ObjId < 0 || ObjId > atomic_load(&XRayNumObjects, memory_order_acquire))
+  if (ObjId < 0 || ObjId >= atomic_load(&XRayNumObjects, memory_order_acquire))
     return 0;
   return XRayInstrMaps[ObjId].Functions;
 }