evas: add logic to do limit output tile to fit in L1 cache.

This code is not turned on by default at the moment as it expose
the cost of walking over and over again Evas_Object stack. We need
to seriously optimize this or maybe i should do it another way.
   Instead we could replay the command list in the asynchronous pipe
by adding cliping and replay as many time as needed. Worth exploring
that option to.

src/modules/evas/engines/software_generic/Evas_Engine_Software_Generic.h

@@ -80,6 +80,7 @@ struct _Render_Engine_Software_Generic
    unsigned char end : 1;
    unsigned char lost_back : 1;
    unsigned char tile_strict : 1;
+   unsigned char tiling : 1;
 };
 
 static inline Eina_Bool
@@ -124,6 +125,9 @@ evas_render_engine_software_generic_init(Render_Engine_Software_Generic *re,
    re->lost_back = 0;
    re->tile_strict = 0;
 
+   if (getenv("EVAS_TILING_ENABLE"))
+     re->tiling = 1;
+
    re->tb = evas_common_tilebuf_new(w, h);
    if (!re->tb) return EINA_FALSE;
 

src/modules/evas/engines/software_generic/evas_engine.c

@@ -2701,6 +2701,37 @@ _merge_rects(Render_Engine_Merge_Mode merge_mode,
    return rects;
 }
 
+static inline Tilebuf_Rect *
+_split_rect_horizontaly(Tilebuf_Rect *it)
+{
+   Tilebuf_Rect *tmp;
+
+   tmp = calloc(1, sizeof(Tilebuf_Rect));
+   if (!tmp) return NULL;
+   tmp->x = it->x + it->w / 2;
+   tmp->w = it->w / 2 + it->w % 2;
+   tmp->y = it->y;
+   tmp->h = it->h;
+   it->w = it->w / 2;
+
+   return tmp;
+}
+
+static inline Tilebuf_Rect *
+_split_rect_verticaly(Tilebuf_Rect *it)
+{
+   Tilebuf_Rect *tmp;
+
+   tmp = calloc(1, sizeof(Tilebuf_Rect));
+   if (!tmp) return NULL;
+   tmp->y = it->y + it->h / 2;
+   tmp->h = it->h / 2 + it->h % 2;
+   tmp->x = it->x;
+   tmp->w = it->w;
+   it->h = it->h / 2;
+
+   return tmp;
+}
 
 static void *
 eng_output_redraws_next_update_get(void *data, int *x, int *y, int *w, int *h, int *cx, int *cy, int *cw, int *ch)
@@ -2775,6 +2806,52 @@ eng_output_redraws_next_update_get(void *data, int *x, int *y, int *w, int *h, i
           }
         evas_common_tilebuf_clear(re->tb);
         re->cur_rect = EINA_INLIST_GET(re->rects);
+
+        if (re->tiling)
+          {
+             /* We will limit each rect to be fiting inside 16KB */
+             Tilebuf_Rect *it;
+
+             EINA_INLIST_FOREACH(re->cur_rect, it)
+               {
+                  while ((it->w * it->h * sizeof (int)) > (16 * 1024))
+                    {
+                       Tilebuf_Rect *tmp;
+
+                       /* Split the largest side first */
+                       if (it->w > it->h)
+                         {
+                            /* Let's try to divide it horizontaly */
+                            tmp = _split_rect_horizontaly(it);
+                            if (!tmp) break;
+                            re->cur_rect = eina_inlist_append(re->cur_rect, EINA_INLIST_GET(tmp));
+
+                            if ((it->w * it->h * sizeof (int)) <= (16 * 1024))
+                              break;
+
+                            /* Let's try to divide it verticaly */
+                            tmp = _split_rect_verticaly(it);
+                            if (!tmp) break;
+                            re->cur_rect = eina_inlist_append(re->cur_rect, EINA_INLIST_GET(tmp));
+                         }
+                       else
+                         {
+                            /* Let's try to divide it verticaly */
+                            tmp = _split_rect_verticaly(it);
+                            if (!tmp) break;
+                            re->cur_rect = eina_inlist_append(re->cur_rect, EINA_INLIST_GET(tmp));
+
+                            if ((it->w * it->h * sizeof (int)) <= (16 * 1024))
+                              break;
+
+                            /* Let's try to divide it horizontaly */
+                            tmp = _split_rect_horizontaly(it);
+                            if (!tmp) break;
+                            re->cur_rect = eina_inlist_append(re->cur_rect, EINA_INLIST_GET(tmp));
+                         }
+                    }
+               }
+          }
      }
    if (!re->cur_rect) return NULL;
    rect = (Tilebuf_Rect *)re->cur_rect;