llvmpipe: Ensure the 16x16 special rasterization path does not touch outside the tile.

llvmpipe has a few special rasterization paths for triangles contained in
16x16 blocks, but it allows the 16x16 block to be aligned only to a 4x4
grid.

Some 16x16 blocks could actually intersect the tile
if the triangle is 16 pixels in one dimension but 4 in the other, causing
a buffer overflow.

The fix consists of budging the 16x16 blocks back inside the tile.

1 files changed, 2 insertions, 0 deletions

diff --git a/src/gallium/drivers/llvmpipe/lp_rast.c b/src/gallium/drivers/llvmpipe/lp_rast.c
index 131785852c8..c4560bfe6c0 100644
--- a/src/gallium/drivers/llvmpipe/lp_rast.c
+++ b/src/gallium/drivers/llvmpipe/lp_rast.c
@@ -436,6 +436,8 @@ lp_rast_shade_quads_mask(struct lp_rasterizer_task *task,
    assert(state);
 
    /* Sanity checks */
+   assert(x < scene->tiles_x * TILE_SIZE);
+   assert(y < scene->tiles_y * TILE_SIZE);
    assert(x % TILE_VECTOR_WIDTH == 0);
    assert(y % TILE_VECTOR_HEIGHT == 0);