pgraph: Refactor RenderAttrib return_new code a little bit

- Allows the compiler to devirtualize the get_hash_impl call, in theory
- Reduces the overhead of checking the configuration variables every time in return_new
- Avoids recalculating the hash on calling get_unique

panda/src/pgraph/config_pgraph.cxx

@@ -214,7 +214,7 @@ ConfigVariableBool transform_cache
           "transforms, but imposes some overhead for maintaining the "
           "cache itself."));
 
-ConfigVariableBool state_cache
+ALIGN_16BYTE ConfigVariableBool state_cache
 ("state-cache", true,
  PRC_DESC("Set this true to enable the cache of RenderState objects, "
           "similar to the TransformState cache controlled via "
@@ -236,7 +236,7 @@ ConfigVariableBool uniquify_states
           "including the need to check for a composition cycle in "
           "the cache.  It is highly recommended to keep this on."));
 
-ConfigVariableBool uniquify_attribs
+ALIGN_16BYTE ConfigVariableBool uniquify_attribs
 ("uniquify-attribs", true,
  PRC_DESC("Set this true to ensure that equivalent RenderAttribs "
           "are pointerwise equal.  This may improve caching performance, "

panda/src/pgraph/config_pgraph.h

@@ -46,10 +46,10 @@ extern ConfigVariableBool auto_break_cycles;
 extern EXPCL_PANDA_PGRAPH ConfigVariableBool garbage_collect_states;
 extern ConfigVariableDouble garbage_collect_states_rate;
 extern ConfigVariableBool transform_cache;
-extern ConfigVariableBool state_cache;
+extern ALIGN_16BYTE EXPCL_PANDA_PGRAPH ConfigVariableBool state_cache;
 extern ConfigVariableBool uniquify_transforms;
 extern EXPCL_PANDA_PGRAPH ConfigVariableBool uniquify_states;
-extern ConfigVariableBool uniquify_attribs;
+extern ALIGN_16BYTE EXPCL_PANDA_PGRAPH ConfigVariableBool uniquify_attribs;
 extern ConfigVariableBool retransform_sprites;
 extern ConfigVariableBool depth_offset_decals;
 extern ConfigVariableInt max_collect_vertices;

panda/src/pgraph/renderAttrib.I

@@ -79,7 +79,11 @@ get_hash() const {
  */
 INLINE CPT(RenderAttrib) RenderAttrib::
 get_unique() const {
-  return return_unique((RenderAttrib *)this);
+  if (state_cache) {
+    return do_uniquify(this);
+  } else {
+    return this;
+  }
 }
 
 /**
@@ -93,6 +97,47 @@ calc_hash() {
   _hash = int_hash::add_hash(hash, get_type().get_index());
 }
 
+/**
+ * This function is used by derived RenderAttrib types to share a common
+ * RenderAttrib pointer for all equivalent RenderAttrib objects.
+ *
+ * This is different from return_unique() in that it does not actually
+ * guarantee a unique pointer, unless uniquify-attribs is set.
+ */
+INLINE CPT(RenderAttrib) RenderAttrib::
+return_new(RenderAttrib *attrib) {
+  nassertr(attrib != nullptr, attrib);
+  attrib->calc_hash();
+
+  if (_uniquify_attribs) {
+    return do_uniquify(attrib);
+  } else {
+    return attrib;
+  }
+}
+
+/**
+ * This function is used by derived RenderAttrib types to share a common
+ * RenderAttrib pointer for all equivalent RenderAttrib objects.
+ *
+ * The make() function of the derived type should create a new RenderAttrib
+ * and pass it through return_new(), which will either save the pointer and
+ * return it unchanged (if this is the first similar such object) or delete it
+ * and return an equivalent pointer (if there was already a similar object
+ * saved).
+ */
+INLINE CPT(RenderAttrib) RenderAttrib::
+return_unique(RenderAttrib *attrib) {
+  nassertr(attrib != nullptr, attrib);
+  attrib->calc_hash();
+
+  if (state_cache) {
+    return do_uniquify(attrib);
+  } else {
+    return attrib;
+  }
+}
+
 /**
  * Adds the indicated TypeHandle to the registry, if it is not there already,
  * and returns a unique slot number.  See RenderAttribRegistry.

panda/src/pgraph/renderAttrib.cxx

@@ -14,7 +14,6 @@
 #include "renderAttrib.h"
 #include "bamReader.h"
 #include "indent.h"
-#include "config_pgraph.h"
 #include "lightReMutexHolder.h"
 #include "pStatTimer.h"
 
@@ -22,6 +21,7 @@ using std::ostream;
 
 LightReMutex *RenderAttrib::_attribs_lock = nullptr;
 RenderAttrib::Attribs RenderAttrib::_attribs;
+bool RenderAttrib::_uniquify_attribs = false;
 TypeHandle RenderAttrib::_type_handle;
 
 size_t RenderAttrib::_garbage_index = 0;
@@ -180,6 +180,10 @@ list_attribs(ostream &out) {
  */
 int RenderAttrib::
 garbage_collect() {
+  // This gets called periodically, so use this opportunity to reload the value
+  // from the Config.prc file.
+  _uniquify_attribs = uniquify_attribs && state_cache;
+
   if (!garbage_collect_states) {
     return 0;
   }
@@ -305,54 +309,15 @@ validate_attribs() {
 }
 
 /**
- * This function is used by derived RenderAttrib types to share a common
- * RenderAttrib pointer for all equivalent RenderAttrib objects.
- *
- * This is different from return_unique() in that it does not actually
- * guarantee a unique pointer, unless uniquify-attribs is set.
- */
-CPT(RenderAttrib) RenderAttrib::
-return_new(RenderAttrib *attrib) {
-  nassertr(attrib != nullptr, attrib);
-  if (!uniquify_attribs) {
-    attrib->calc_hash();
-    return attrib;
-  }
-
-  return return_unique(attrib);
-}
-
-/**
- * This function is used by derived RenderAttrib types to share a common
- * RenderAttrib pointer for all equivalent RenderAttrib objects.
- *
- * The make() function of the derived type should create a new RenderAttrib
- * and pass it through return_new(), which will either save the pointer and
- * return it unchanged (if this is the first similar such object) or delete it
- * and return an equivalent pointer (if there was already a similar object
- * saved).
+ * Private implementation of return_new, return_unique, and get_unique.
  */
 CPT(RenderAttrib) RenderAttrib::
-return_unique(RenderAttrib *attrib) {
-  nassertr(attrib != nullptr, attrib);
-
-  attrib->calc_hash();
-
-  if (!state_cache) {
-    return attrib;
-  }
-
-#ifndef NDEBUG
-  if (paranoid_const) {
-    nassertr(validate_attribs(), attrib);
-  }
-#endif
-
+do_uniquify(const RenderAttrib *attrib) {
   LightReMutexHolder holder(*_attribs_lock);
 
   if (attrib->_saved_entry != -1) {
-    // This attrib is already in the cache.  nassertr(_attribs.find(attrib)
-    // == attrib->_saved_entry, attrib);
+    // This attrib is already in the cache.
+    //nassertr(_attribs.find(attrib) == attrib->_saved_entry, attrib);
     return attrib;
   }
 
@@ -503,6 +468,12 @@ release_new() {
  */
 void RenderAttrib::
 init_attribs() {
+  // These are copied here so that we can be sure that they are constructed.
+  ALIGN_16BYTE ConfigVariableBool uniquify_attribs("uniquify-attribs", true);
+  ALIGN_16BYTE ConfigVariableBool state_cache("state-cache", true);
+
+  _uniquify_attribs = uniquify_attribs && state_cache;
+
   // TODO: we should have a global Panda mutex to allow us to safely create
   // _attribs_lock without a startup race condition.  For the meantime, this
   // is OK because we guarantee that this method is called at static init

panda/src/pgraph/renderAttrib.h

@@ -16,6 +16,7 @@
 
 #include "pandabase.h"
 
+#include "config_pgraph.h"
 #include "typedWritableReferenceCount.h"
 #include "renderAttribRegistry.h"
 #include "pointerTo.h"
@@ -161,8 +162,9 @@ PUBLISHED:
 protected:
   INLINE void calc_hash();
 
-  static CPT(RenderAttrib) return_new(RenderAttrib *attrib);
-  static CPT(RenderAttrib) return_unique(RenderAttrib *attrib);
+  INLINE static CPT(RenderAttrib) return_new(RenderAttrib *attrib);
+  INLINE static CPT(RenderAttrib) return_unique(RenderAttrib *attrib);
+  static CPT(RenderAttrib) do_uniquify(const RenderAttrib *attrib);
   virtual int compare_to_impl(const RenderAttrib *other) const;
   virtual size_t get_hash_impl() const;
   virtual CPT(RenderAttrib) compose_impl(const RenderAttrib *other) const;
@@ -184,8 +186,9 @@ private:
   static LightReMutex *_attribs_lock;
   typedef SimpleHashMap<const RenderAttrib *, std::nullptr_t, indirect_compare_to_hash<const RenderAttrib *> > Attribs;
   static Attribs _attribs;
+  static bool _uniquify_attribs;
 
-  int _saved_entry;
+  mutable int _saved_entry;
   size_t _hash;
 
   // This keeps track of our current position through the garbage collection
@@ -195,6 +198,7 @@ private:
   static PStatCollector _garbage_collect_pcollector;
 
   friend class RenderAttribRegistry;
+  friend class RenderState;
 
 public:
   virtual void write_datagram(BamWriter *manager, Datagram &dg);

panda/src/pgraph/renderState.cxx

@@ -1287,8 +1287,8 @@ return_unique(RenderState *state) {
   LightReMutexHolder holder(*_states_lock);
 
   if (state->_saved_entry != -1) {
-    // This state is already in the cache.  nassertr(_states.find(state) ==
-    // state->_saved_entry, pt_state);
+    // This state is already in the cache.
+    //nassertr(_states.find(state) == state->_saved_entry, pt_state);
     return state;
   }
 
@@ -1300,7 +1300,7 @@ return_unique(RenderState *state) {
     while (slot >= 0) {
       Attribute &attrib = state->_attributes[slot];
       nassertd(attrib._attrib != nullptr) continue;
-      attrib._attrib = attrib._attrib->get_unique();
+      attrib._attrib = RenderAttrib::do_uniquify(attrib._attrib);
       mask.clear_bit(slot);
       slot = mask.get_lowest_on_bit();
     }