softpipe: Make softpipe transfers in-order.

Transfer, being now a context operation, should happen in order with
all other contexts operations. If there is rendering pending on the
resource then the driver must flush and potentially wait itself
internally.

Instead of avoiding using transfers internally (as done in llvmpipe) I've
opted to simply pass PIPE_TRANSFER_UNSYNCHRONIZED in all internal
transfers, to avoid infinite recursion.

src/gallium/drivers/softpipe/sp_flush.c

@@ -104,3 +104,71 @@ softpipe_flush( struct pipe_context *pipe,
       *fence = NULL;
 }
 
+
+/**
+ * Flush context if necessary.
+ *
+ * Returns FALSE if it would have block, but do_not_block was set, TRUE
+ * otherwise.
+ *
+ * TODO: move this logic to an auxiliary library?
+ */
+boolean
+softpipe_flush_resource(struct pipe_context *pipe,
+                        struct pipe_resource *texture,
+                        unsigned face,
+                        unsigned level,
+                        unsigned flush_flags,
+                        boolean read_only,
+                        boolean cpu_access,
+                        boolean do_not_block)
+{
+   unsigned referenced;
+
+   referenced = pipe->is_resource_referenced(pipe, texture, face, level);
+
+   if ((referenced & PIPE_REFERENCED_FOR_WRITE) ||
+       ((referenced & PIPE_REFERENCED_FOR_READ) && !read_only)) {
+
+      /*
+       * TODO: The semantics of these flush flags are too obtuse. They should
+       * disappear and the pipe driver should just ensure that all visible
+       * side-effects happen when they need to happen.
+       */
+      if (referenced & PIPE_REFERENCED_FOR_WRITE)
+         flush_flags |= PIPE_FLUSH_RENDER_CACHE;
+
+      if (referenced & PIPE_REFERENCED_FOR_READ)
+         flush_flags |= PIPE_FLUSH_TEXTURE_CACHE;
+
+      if (cpu_access) {
+         /*
+          * Flush and wait.
+          */
+
+         struct pipe_fence_handle *fence = NULL;
+
+         if (do_not_block)
+            return FALSE;
+
+         pipe->flush(pipe, flush_flags, &fence);
+
+         if (fence) {
+            /*
+             * This is for illustrative purposes only, as softpipe does not
+             * have fences.
+             */
+            pipe->screen->fence_finish(pipe->screen, fence, 0);
+            pipe->screen->fence_reference(pipe->screen, &fence, NULL);
+         }
+      } else {
+         /*
+          * Just flush.
+          */
+
+         pipe->flush(pipe, flush_flags, NULL);
+      }
+   }
+
+   return TRUE;
+}

src/gallium/drivers/softpipe/sp_flush.h

@@ -28,10 +28,23 @@
 #ifndef SP_FLUSH_H
 #define SP_FLUSH_H
 
+#include "pipe/p_compiler.h"
+
 struct pipe_context;
 struct pipe_fence_handle;
 
-void softpipe_flush(struct pipe_context *pipe, unsigned flags,
-                    struct pipe_fence_handle **fence);
+void
+softpipe_flush(struct pipe_context *pipe, unsigned flags,
+               struct pipe_fence_handle **fence);
+
+boolean
+softpipe_flush_resource(struct pipe_context *pipe,
+                        struct pipe_resource *texture,
+                        unsigned face,
+                        unsigned level,
+                        unsigned flush_flags,
+                        boolean read_only,
+                        boolean cpu_access,
+                        boolean do_not_block);
 
 #endif

src/gallium/drivers/softpipe/sp_tex_tile_cache.c

@@ -248,7 +248,8 @@ sp_find_cached_tile_tex(struct softpipe_tex_tile_cache *tc,
 			      addr.bits.face, 
 			      addr.bits.level, 
 			      addr.bits.z, 
-			      PIPE_TRANSFER_READ, 0, 0,
+			      PIPE_TRANSFER_READ | PIPE_TRANSFER_UNSYNCHRONIZED,
+			      0, 0,
 			      u_minify(tc->texture->width0, addr.bits.level),
 			      u_minify(tc->texture->height0, addr.bits.level));
          

src/gallium/drivers/softpipe/sp_texture.c

@@ -39,6 +39,7 @@
 #include "util/u_transfer.h"
 
 #include "sp_context.h"
+#include "sp_flush.h"
 #include "sp_texture.h"
 #include "sp_screen.h"
 
@@ -301,6 +302,27 @@ softpipe_get_transfer(struct pipe_context *pipe,
    assert(box->y + box->height <= u_minify(resource->height0, sr.level));
    assert(box->z + box->depth <= u_minify(resource->depth0, sr.level));
 
+   /*
+    * Transfers, like other pipe operations, must happen in order, so flush the
+    * context if necessary.
+    */
+   if (!(usage & PIPE_TRANSFER_UNSYNCHRONIZED)) {
+      boolean read_only = !(usage & PIPE_TRANSFER_WRITE);
+      boolean do_not_block = !!(usage & PIPE_TRANSFER_DONTBLOCK);
+      if (!softpipe_flush_resource(pipe, resource,
+                                   sr.face, sr.level,
+                                   0, /* flush_flags */
+                                   read_only,
+                                   TRUE, /* cpu_access */
+                                   do_not_block)) {
+         /*
+          * It would have blocked, but state tracker requested no to.
+          */
+         assert(do_not_block);
+         return NULL;
+      }
+   }
+
    spr = CALLOC_STRUCT(softpipe_transfer);
    if (spr) {
       struct pipe_transfer *pt = &spr->base;

src/gallium/drivers/softpipe/sp_tile_cache.c

@@ -155,7 +155,8 @@ sp_tile_cache_set_surface(struct softpipe_tile_cache *tc,
    if (ps) {
       tc->transfer = pipe_get_transfer(pipe, ps->texture, ps->face,
 					   ps->level, ps->zslice,
-					   PIPE_TRANSFER_READ_WRITE,
+					   PIPE_TRANSFER_READ_WRITE |
+					   PIPE_TRANSFER_UNSYNCHRONIZED,
 					   0, 0, ps->width, ps->height);
 
       tc->depth_stencil = (ps->format == PIPE_FORMAT_Z24_UNORM_S8_USCALED ||