vrend,blit: Use the GL fallback on GLES in more cases

The GL fallback also must be used on GLES if the target surface is
a multi-sample surface or if the region blitted from a multi-sample
surface is not equal to the target region.

This patch results in piglit reporing regressions with

  multisample-blit * depth

on a GLES host. However, these piglits make bits to MS surfaces which
is not supported by glBlitFramebuffer on GLES. The old code took that
path, and mesa would actually report an error when compiled with -DDEBUG
butthe piglits still reported success. Unfortunately, resolving the MS
propperly is quite a challange for depth textures, and requires information
that is not available in the blit info (zNear and zFar), so getting these
piglits to act correcly on GLES hosts seems quite impossible.

v2: Also use fallback on GLES if the source is multi-sample and the formats
    of source and dest are not equal

Signed-off-by: Gert Wollny <gert.wollny@collabora.com>
Reviewed-by: Gurchetan Singh <gurchetansingh@chromium.org>

src/vrend_renderer.c

@@ -7646,6 +7646,42 @@ static void vrend_renderer_blit_int(struct vrend_context *ctx,
          use_gl = true;
    }
 
+   if (!dst_res->y_0_top) {
+      dst_y1 = info->dst.box.y + info->dst.box.height;
+      dst_y2 = info->dst.box.y;
+   } else {
+      dst_y1 = dst_res->base.height0 - info->dst.box.y - info->dst.box.height;
+      dst_y2 = dst_res->base.height0 - info->dst.box.y;
+   }
+
+   if (!src_res->y_0_top) {
+      src_y1 = info->src.box.y + info->src.box.height;
+      src_y2 = info->src.box.y;
+   } else {
+      src_y1 = src_res->base.height0 - info->src.box.y - info->src.box.height;
+      src_y2 = src_res->base.height0 - info->src.box.y;
+   }
+
+   /* GLES generally doesn't support blitting to a multi-sample FB, and also not
+    * from a multi-sample FB where the regions are not exatly the same or the
+    * source and target format are different. For
+    * downsampling DS blits to zero samples we solve this by doing two blits */
+   if (vrend_state.use_gles &&
+       (info->mask & PIPE_MASK_RGBA) &&
+       (dst_res->base.nr_samples > 1 ||
+        (src_res->base.nr_samples > 1 &&
+         (info->src.box.x != info->dst.box.x ||
+          info->src.box.width != info->dst.box.width ||
+          dst_y1 != src_y1 || dst_y2 != src_y2 ||
+          info->src.format != info->dst.format))
+        )
+       ) {
+      VREND_DEBUG(dbg_blit, ctx, "Use GL fallback because dst:ms:%d src:ms:%d (%d %d %d %d) -> (%d %d %d %d)\n",
+                  dst_res->base.nr_samples, src_res->base.nr_samples, info->src.box.x, info->src.box.x + info->src.box.width,
+                  src_y1, src_y2, info->dst.box.x, info->dst.box.x + info->dst.box.width, dst_y1, dst_y2);
+      use_gl = true;
+   }
+
    /* for 3D mipmapped blits - hand roll time */
    if (info->src.box.depth != info->dst.box.depth)
       use_gl = true;
@@ -7676,21 +7712,6 @@ static void vrend_renderer_blit_int(struct vrend_context *ctx,
    if (info->mask & PIPE_MASK_RGBA)
       glmask |= GL_COLOR_BUFFER_BIT;
 
-   if (!dst_res->y_0_top) {
-      dst_y1 = info->dst.box.y + info->dst.box.height;
-      dst_y2 = info->dst.box.y;
-   } else {
-      dst_y1 = dst_res->base.height0 - info->dst.box.y - info->dst.box.height;
-      dst_y2 = dst_res->base.height0 - info->dst.box.y;
-   }
-
-   if (!src_res->y_0_top) {
-      src_y1 = info->src.box.y + info->src.box.height;
-      src_y2 = info->src.box.y;
-   } else {
-      src_y1 = src_res->base.height0 - info->src.box.y - info->src.box.height;
-      src_y2 = src_res->base.height0 - info->src.box.y;
-   }
 
    if (info->scissor_enable) {
       glScissor(info->scissor.minx, info->scissor.miny, info->scissor.maxx - info->scissor.minx, info->scissor.maxy - info->scissor.miny);