wined3d: Skip copying the depth stencil if it's discarded.

dlls/wined3d/device.c

@@ -6647,10 +6647,15 @@ static HRESULT WINAPI IWineD3DDeviceImpl_SetDepthStencilSurface(IWineD3DDevice *
          ******************************************************/
 
         if (This->stencilBufferTarget) {
+            if (((IWineD3DSwapChainImpl *)This->swapchains[0])->presentParms.Flags & WINED3DPRESENTFLAG_DISCARD_DEPTHSTENCIL
+                    || ((IWineD3DSurfaceImpl *)This->stencilBufferTarget)->Flags & SFLAG_DISCARD) {
+                surface_modify_ds_location(This->stencilBufferTarget, SFLAG_DS_DISCARDED);
+            } else {
                 ActivateContext(This, This->render_targets[0], CTXUSAGE_RESOURCELOAD);
                 surface_load_ds_location(This->stencilBufferTarget, SFLAG_DS_OFFSCREEN);
                 surface_modify_ds_location(This->stencilBufferTarget, SFLAG_DS_OFFSCREEN);
             }
+        }
 
         tmp = This->stencilBufferTarget;
         This->stencilBufferTarget = pNewZStencil;

dlls/wined3d/swapchain.c

@@ -259,6 +259,13 @@ static HRESULT WINAPI IWineD3DSwapChainImpl_Present(IWineD3DSwapChain *iface, CO
         }
     }
 
+    if (This->wineD3DDevice->stencilBufferTarget) {
+        if (This->presentParms.Flags & WINED3DPRESENTFLAG_DISCARD_DEPTHSTENCIL
+                || ((IWineD3DSurfaceImpl *)This->wineD3DDevice->stencilBufferTarget)->Flags & SFLAG_DISCARD) {
+            surface_modify_ds_location(This->wineD3DDevice->stencilBufferTarget, SFLAG_DS_DISCARDED);
+        }
+    }
+
     if(This->presentParms.PresentationInterval != WINED3DPRESENT_INTERVAL_IMMEDIATE && GL_SUPPORT(SGI_VIDEO_SYNC)) {
         retval = GL_EXTCALL(glXGetVideoSyncSGI(&sync));
         if(retval != 0) {

dlls/wined3d/wined3d_private.h

@@ -1449,6 +1449,7 @@ void flip_surface(IWineD3DSurfaceImpl *front, IWineD3DSurfaceImpl *back);
 
 #define SFLAG_DS_LOCATIONS  (SFLAG_DS_ONSCREEN | \
                              SFLAG_DS_OFFSCREEN)
+#define SFLAG_DS_DISCARDED   SFLAG_DS_LOCATIONS
 
 BOOL CalculateTexRect(IWineD3DSurfaceImpl *This, RECT *Rect, float glTexCoord[4]);