llvmpipe: fix bogus handling of first_layer when setting up texture sampling

The code avoided first_layer parameter in the sampler interface (and needing
to do another calculation at runtime) by fixing up the base texture pointer
instead. Unfortunately, this didn't actually work as we have mip-first
texture layout so fixing up the base ptr by a fixed amount is very wrong if
there are mipmaps present. The wrong offsets caused misrendering and crashes.
Fix this by just adjusting the individual mip level offsets instead.
Spotted by Jose.

Reviewed-by: Jose Fonseca <jfonseca@vmware.com>

2 files changed, 18 insertions, 14 deletions

diff --git a/src/gallium/drivers/llvmpipe/lp_setup.c b/src/gallium/drivers/llvmpipe/lp_setup.c
index 8c9f0c64653..f9cbdaba62c 100644
--- a/src/gallium/drivers/llvmpipe/lp_setup.c
+++ b/src/gallium/drivers/llvmpipe/lp_setup.c
@@ -748,26 +748,28 @@ lp_setup_set_fragment_sampler_views(struct lp_setup_context *setup,
                      jit_tex->img_stride[j] = lp_tex->img_stride[j];
                   }
 
-		  /* FIXME: This is incorrect, as currently layer stride depends on miplevel */
-#if 0
-                  /*
-                   * We don't use anything like first_element (for buffers) or
-                   * first_layer (for arrays), instead adjust the last_element
-                   * (width) or last_layer (depth) plus the base pointer.
-                   * Less parameters and faster at shader execution.
-                   * XXX Could do the same for mip levels.
-                   */
                   if (res->target == PIPE_TEXTURE_1D_ARRAY ||
                       res->target == PIPE_TEXTURE_2D_ARRAY) {
+                     /*
+                      * For array textures, we don't have first_layer, instead
+                      * adjust last_layer (stored as depth) plus the mip level offsets
+                      * (as we have mip-first layout can't just adjust base ptr).
+                      * XXX For mip levels, could do something similar.
+                      */
                      jit_tex->depth = view->u.tex.last_layer - view->u.tex.first_layer + 1;
-                     jit_tex->base = (uint8_t *)jit_tex->base +
-                                     view->u.tex.first_layer * lp_tex->img_stride[0];
+                     for (j = first_level; j <= last_level; j++) {
+                        jit_tex->mip_offsets[j] += view->u.tex.first_layer *
+                                                   lp_tex->img_stride[j];
+                     }
                      assert(view->u.tex.first_layer <= view->u.tex.last_layer);
                      assert(view->u.tex.last_layer < res->array_size);
                   }
-#endif
                }
                else {
+                  /*
+                   * For buffers, we don't have first_element, instead adjust
+                   * last_element (stored as width) plus the base pointer.
+                   */
                   unsigned view_blocksize = util_format_get_blocksize(view->format);
                   /* probably don't really need to fill that out */
                   jit_tex->mip_offsets[0] = 0;
diff --git a/src/gallium/drivers/llvmpipe/lp_state_sampler.c b/src/gallium/drivers/llvmpipe/lp_state_sampler.c
index 6498d130e06..6b7e327e0fb 100644
--- a/src/gallium/drivers/llvmpipe/lp_state_sampler.c
+++ b/src/gallium/drivers/llvmpipe/lp_state_sampler.c
@@ -320,8 +320,10 @@ prepare_shader_sampling(
                if (res->target == PIPE_TEXTURE_1D_ARRAY ||
                    res->target == PIPE_TEXTURE_2D_ARRAY) {
                   num_layers = view->u.tex.last_layer - view->u.tex.first_layer + 1;
-                  addr = (uint8_t *)addr +
-                                  view->u.tex.first_layer * lp_tex->img_stride[0];
+                  for (j = first_level; j <= last_level; j++) {
+                     mip_offsets[j] += view->u.tex.first_layer *
+                                       lp_tex->img_stride[j];
+                  }
                   assert(view->u.tex.first_layer <= view->u.tex.last_layer);
                   assert(view->u.tex.last_layer < res->array_size);
                }