From bc7858bb87b7150077a77c8da2a562bd74bbc0f5 Mon Sep 17 00:00:00 2001
From: Bill Currie <bill@taniwha.org>
Date: Wed, 3 Feb 2021 11:41:38 +0900
Subject: [PATCH] [model] Move parent pointer out of leaf/node struct

The node struct was 72 bytes thus two cache line. Moving the pointer
into the brush model data block allows nodes to fit in a single cache
line (not that they're aligned yet, but that's next). It doesn't seem to
have made any difference to performance (at least in the vulkan
renderer), but it hasn't hurt, either, as the only place that needed the
parent pointer was R_MarkLeaves.
---
 include/QF/model.h              |  7 +++----
 libs/models/brush/model_brush.c | 17 +++++++++++------
 libs/video/renderer/r_bsp.c     | 16 +++++++++-------
 3 files changed, 23 insertions(+), 17 deletions(-)

diff --git a/include/QF/model.h b/include/QF/model.h
index a05d489a4..b65a5ad18 100644
--- a/include/QF/model.h
+++ b/include/QF/model.h
@@ -179,8 +179,6 @@ typedef struct mnode_s {
 
 	float		minmaxs[6];		// for bounding box culling
 
-	struct mnode_s	*parent;
-
 // node specific
 	plane_t		*plane;
 	struct mnode_s	*children[2];
@@ -198,8 +196,6 @@ typedef struct mleaf_s {
 	float		mins[3];
 	float		maxs[3];
 
-	struct mnode_s	*parent;
-
 // leaf specific
 	byte		*compressed_vis;
 	efrag_t		*efrags;
@@ -274,6 +270,9 @@ typedef struct mod_brush_s {
 	byte		*lightdata;
 	char		*entities;	//FIXME should not be here
 
+	mnode_t    **node_parents;
+	mnode_t    **leaf_parents;
+
 	unsigned int checksum;
 	unsigned int checksum2;
 } mod_brush_t;
diff --git a/libs/models/brush/model_brush.c b/libs/models/brush/model_brush.c
index 8a703050d..b18de9076 100644
--- a/libs/models/brush/model_brush.c
+++ b/libs/models/brush/model_brush.c
@@ -585,13 +585,15 @@ Mod_LoadFaces (model_t *mod, bsp_t *bsp)
 }
 
 static void
-Mod_SetParent (mnode_t *node, mnode_t *parent)
+Mod_SetParent (mod_brush_t *brush, mnode_t *node, mnode_t *parent)
 {
-	node->parent = parent;
-	if (node->contents < 0)
+	if (node->contents < 0) {
+		brush->leaf_parents[(mleaf_t *)node - brush->leafs] = parent;
 		return;
-	Mod_SetParent (node->children[0], node);
-	Mod_SetParent (node->children[1], node);
+	}
+	brush->node_parents[node - brush->nodes] = parent;
+	Mod_SetParent (brush, node->children[0], node);
+	Mod_SetParent (brush, node->children[1], node);
 }
 
 static void
@@ -646,7 +648,10 @@ Mod_LoadNodes (model_t *mod, bsp_t *bsp)
 		}
 	}
 
-	Mod_SetParent (brush->nodes, NULL);	// sets nodes and leafs
+	size_t      size = (brush->numleafs + brush->numnodes) * sizeof (mnode_t *);
+	brush->node_parents = Hunk_AllocName (size, mod->name);
+	brush->leaf_parents = brush->node_parents + brush->numnodes;
+	Mod_SetParent (brush, brush->nodes, NULL);	// sets nodes and leafs
 }
 
 static void
diff --git a/libs/video/renderer/r_bsp.c b/libs/video/renderer/r_bsp.c
index 2475873a5..47b78a643 100644
--- a/libs/video/renderer/r_bsp.c
+++ b/libs/video/renderer/r_bsp.c
@@ -54,6 +54,7 @@ R_MarkLeaves (void)
 	mleaf_t     *leaf;
 	mnode_t     *node;
 	msurface_t **mark;
+	mod_brush_t *brush = &r_worldentity.model->brush;
 
 	if (r_oldviewleaf == r_viewleaf && !r_novis->int_val)
 		return;
@@ -67,13 +68,13 @@ R_MarkLeaves (void)
 		r_oldviewleaf = 0;	// so vis will be recalcualted when novis gets
 							// turned off
 		vis = solid;
-		memset (solid, 0xff, (r_worldentity.model->brush.numleafs + 7) >> 3);
+		memset (solid, 0xff, (brush->numleafs + 7) >> 3);
 	} else
 		vis = Mod_LeafPVS (r_viewleaf, r_worldentity.model);
 
-	for (i = 0; (int) i < r_worldentity.model->brush.numleafs; i++) {
+	for (i = 0; (int) i < brush->numleafs; i++) {
 		if (vis[i >> 3] & (1 << (i & 7))) {
-			leaf = &r_worldentity.model->brush.leafs[i + 1];
+			leaf = &brush->leafs[i + 1];
 			if ((c = leaf->nummarksurfaces)) {
 				mark = leaf->firstmarksurface;
 				do {
@@ -81,13 +82,14 @@ R_MarkLeaves (void)
 					mark++;
 				} while (--c);
 			}
-			node = (mnode_t *) leaf;
-			do {
+			leaf->visframe = r_visframecount;
+			node = brush->leaf_parents[leaf - brush->leafs];
+			while (node) {
 				if (node->visframe == r_visframecount)
 					break;
 				node->visframe = r_visframecount;
-				node = node->parent;
-			} while (node);
+				node = brush->node_parents[node - brush->nodes];
+			}
 		}
 	}
 }