[Mesa-dev] [PATCH] st/mesa: use base level size as "guess" when available

[Nicolai Hähnle]

From: Nicolai Hähnle <nicolai.haehnle at amd.com>

When an applications specifies mip levels _before_ setting a mipmap texture
filter, we will initially guess a single texture level. When the second level
image is created, we try to allocate the full texture -- however, we get the
base level size guess wrong if that size is odd. This leads to yet another
re-allocation of the texture later during st_finalize_texture.

Even worse, this re-allocation breaks a (reasonable) assumption made by
st_generate_mipmaps, because the re-allocation in the finalization call will
again allocate a single-level pipe texture (based on the non-mipmap texture
filter!). As a result, mipmap generation fails in interesting ways.

All of this can be avoided by just using the fact that we already know the
size of the base level.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=95529
Cc: 12.0 <mesa-stable at lists.freedesktop.org>
---
 src/mesa/state_tracker/st_cb_texture.c | 33 +++++++++++++++++++++++++++------
 1 file changed, 27 insertions(+), 6 deletions(-)

diff --git a/src/mesa/state_tracker/st_cb_texture.c b/src/mesa/state_tracker/st_cb_texture.c
index d38f24c..44e21b1 100644
--- a/src/mesa/state_tracker/st_cb_texture.c
+++ b/src/mesa/state_tracker/st_cb_texture.c
@@ -456,21 +456,42 @@ guess_and_alloc_texture(struct st_context *st,
 			struct st_texture_object *stObj,
 			const struct st_texture_image *stImage)
 {
+   const struct gl_texture_image *firstImage;
    GLuint lastLevel, width, height, depth;
    GLuint bindings;
    GLuint ptWidth, ptHeight, ptDepth, ptLayers;
    enum pipe_format fmt;
+   bool guessed_box = false;
 
    DBG("%s\n", __func__);
 
    assert(!stObj->pt);
 
-   if (!guess_base_level_size(stObj->base.Target,
-                              stImage->base.Width2,
-                              stImage->base.Height2,
-                              stImage->base.Depth2,
-                              stImage->base.Level,
-                              &width, &height, &depth)) {
+   /* If a base level image with compatible size exists, use that as our guess.
+    */
+   firstImage = _mesa_base_tex_image(&stObj->base);
+   if (firstImage &&
+       guess_base_level_size(stObj->base.Target,
+                             firstImage->Width2,
+                             firstImage->Height2,
+                             firstImage->Depth2,
+                             firstImage->Level,
+                             &width, &height, &depth)) {
+      if (stImage->base.Width2 == u_minify(width, stImage->base.Level) &&
+          stImage->base.Height2 == u_minify(height, stImage->base.Level) &&
+          stImage->base.Depth2 == u_minify(depth, stImage->base.Level))
+         guessed_box = true;
+   }
+
+   if (!guessed_box)
+      guessed_box = guess_base_level_size(stObj->base.Target,
+                                          stImage->base.Width2,
+                                          stImage->base.Height2,
+                                          stImage->base.Depth2,
+                                          stImage->base.Level,
+                                          &width, &height, &depth);
+
+   if (!guessed_box) {
       /* we can't determine the image size at level=0 */
       stObj->width0 = stObj->height0 = stObj->depth0 = 0;
       /* this is not an out of memory error */
-- 
2.7.4