Add variable debug variables when we have debug info

* We don't want to wait until the first store to do this, since the source
  variables are added at the appropriate scope - even before the first store.

renderdoc/driver/shaders/spirv/spirv_debug.cpp

@@ -184,9 +184,14 @@ void ThreadState::EnterFunction(const rdcarray<Id> &arguments)
 
   frame->locals.resize(numVars);
 
-  // don't add source vars for variables, we'll add it on the first store
   ShaderDebugState *state = m_State;
-  m_State = NULL;
+
+  // don't add variables if we don't have debug info, we'll add it on the first store to reduce
+  // noise on unoptimised shaders with lots of variables and no scope information. However if we
+  // have debug info we'll add the variable immediately because the source variable will only be
+  // added at the correct scope and we want to display that before it's stored to.
+  if(!debugger.HasDebugInfo())
+    m_State = NULL;
 
   size_t i = 0;
   // handle any variable declarations

renderdoc/driver/shaders/spirv/spirv_debug.h

@@ -289,6 +289,7 @@ public:
   const DataType &GetTypeForId(Id ssaId);
   const Decorations &GetDecorations(Id typeId);
   bool IsDebugExtInstSet(Id id) const;
+  bool HasDebugInfo() const { return m_DebugInfo.valid; }
   rdcstr GetRawName(Id id) const;
   rdcstr GetHumanName(Id id);
   void AddSourceVars(rdcarray<SourceVariableMapping> &sourceVars, const ShaderVariable &var, Id id);