[PATCH 2/5] wined3d: Use the default queue index for resource fencing.

[Stefan Dösinger]

This removes tracking work entirely from the CS thread and replaces
interlocked with regular writes on the main thread. It also avoids
accessing access_count in read-write mode from two threads.

Signed-off-by: Stefan Dösinger <stefan at codeweavers.com>
---
 dlls/wined3d/cs.c              |  4 ---
 dlls/wined3d/wined3d_private.h | 65 ++++++++++++++++++++++++++--------
 2 files changed, 51 insertions(+), 18 deletions(-)

diff --git a/dlls/wined3d/cs.c b/dlls/wined3d/cs.c
index c4d68fd8f4f..0d6cf747d8f 100644
--- a/dlls/wined3d/cs.c
+++ b/dlls/wined3d/cs.c
@@ -2755,8 +2755,6 @@ static void wined3d_cs_exec_update_sub_resource(struct wined3d_cs *cs, const voi
 
     context_release(context);
 
-    wined3d_resource_release(resource);
-
     if (op->bo.flags & UPLOAD_BO_FREE_ON_UNMAP)
     {
         if (op->bo.addr.buffer_object)
@@ -2803,8 +2801,6 @@ void wined3d_device_context_emit_update_sub_resource(struct wined3d_device_conte
     op->row_pitch = row_pitch;
     op->slice_pitch = slice_pitch;
 
-    wined3d_device_context_acquire_resource(context, resource);
-
     wined3d_device_context_submit(context, WINED3D_CS_QUEUE_MAP);
     /* The data pointer may go away, so we need to wait until it is read.
      * Copying the data may be faster if it's small. */
diff --git a/dlls/wined3d/wined3d_private.h b/dlls/wined3d/wined3d_private.h
index 895f7a76a26..c7f22fda1fa 100644
--- a/dlls/wined3d/wined3d_private.h
+++ b/dlls/wined3d/wined3d_private.h
@@ -4270,7 +4270,7 @@ struct wined3d_resource
     LONG ref;
     LONG bind_count;
     LONG map_count;
-    LONG access_count;
+    ULONG access_time;
     struct wined3d_device *device;
     enum wined3d_resource_type type;
     enum wined3d_gl_resource_type gl_type;
@@ -4314,17 +4314,6 @@ static inline ULONG wined3d_resource_decref(struct wined3d_resource *resource)
     return resource->resource_ops->resource_decref(resource);
 }
 
-static inline void wined3d_resource_acquire(struct wined3d_resource *resource)
-{
-    InterlockedIncrement(&resource->access_count);
-}
-
-static inline void wined3d_resource_release(struct wined3d_resource *resource)
-{
-    LONG refcount = InterlockedDecrement(&resource->access_count);
-    assert(refcount >= 0);
-}
-
 static inline HRESULT wined3d_resource_get_sub_resource_desc(struct wined3d_resource *resource,
         unsigned int sub_resource_idx, struct wined3d_sub_resource_desc *desc)
 {
@@ -5091,16 +5080,64 @@ void wined3d_device_context_emit_update_sub_resource(struct wined3d_device_conte
 HRESULT wined3d_device_context_emit_unmap(struct wined3d_device_context *context,
         struct wined3d_resource *resource, unsigned int sub_resource_idx) DECLSPEC_HIDDEN;
 
-static inline void wined3d_resource_wait_idle(struct wined3d_resource *resource)
+static inline void wined3d_resource_acquire(struct wined3d_resource *resource)
 {
     const struct wined3d_cs *cs = resource->device->cs;
+    resource->access_time = cs->queue[WINED3D_CS_QUEUE_DEFAULT].head;
+}
+
+static inline void wined3d_resource_release(struct wined3d_resource *resource)
+{
+}
+
+static inline void wined3d_resource_wait_idle(const struct wined3d_resource *resource)
+{
+    const struct wined3d_cs *cs = resource->device->cs;
+    ULONG access_time, tail, head;
 
     if (!cs->thread || cs->thread_id == GetCurrentThreadId())
         return;
 
-    while (InterlockedCompareExchange(&resource->access_count, 0, 0))
+    access_time = resource->access_time;
+    head = cs->queue[WINED3D_CS_QUEUE_DEFAULT].head;
+
+    /* The basic idea is that a resource is busy if tail < access_time <= head.
+     * But we have to be careful about wrap-around of the head and tail. The
+     * GE_WRAP macro below considers x >= y if x - y is smaller than half the
+     * UINT range. Head is at most WINED3D_CS_QUEUE_SIZE ahead of tail, because
+     * otherwise the queue memory is considered full and queue_require_space
+     * stalls. Thus GE_WRAP(head, tail) is always true. The C_ASSERT below ensures
+     * this in case we decide to grow the queue size in the future.
+     *
+     * It is possible that a resource has not been used for a long time and is idle, but the head and
+     * tail wrapped around in such a way that the previously set access time falls between head and tail.
+     * In this case we will incorrectly wait for the resource. Because we use the entire 32 bits of the
+     * counters and not just the bits needed to address the actual queue memory, this should happen rarely.
+     * If it turns out to be a problem we can switch to 64 bit counters or attempt to somehow mark the
+     * access time of resources invalid. CS packets are at least 4 byte aligned, so we could use the lower
+     * 2 bits in access_time for such a marker.
+     *
+     * Note that the access time is set before the command is submitted, so we have to wait until the
+     * tail is bigger than access_time, not equal. */
+
+#define GE_WRAP(x, y) (((x)-(y)) < (UINT_MAX / 2))
+    if (!GE_WRAP(head, access_time))
+        return;
+
+    while (1)
+    {
+        tail = *(volatile ULONG *)&cs->queue[WINED3D_CS_QUEUE_DEFAULT].tail;
+        if (head == tail) /* Queue empty. */
+            break;
+
+        if (!GE_WRAP(access_time, tail) && access_time != tail)
+            break;
+
         YieldProcessor();
+    }
+#undef GE_WRAP
 }
+C_ASSERT(WINED3D_CS_QUEUE_SIZE < UINT_MAX / 4);
 
 /* TODO: Add tests and support for FLOAT16_4 POSITIONT, D3DCOLOR position, other
  * fixed function semantics as D3DCOLOR or FLOAT16 */
-- 
2.34.1