9d1334d2a0
This is similar to intel_miptree_map_blit and intel_buffer_object.c's temporary blits in i965. Improves performance of DiRT Rally by 20-25% by eliminating stalls. Breaks piglit's spec/arb_shader_image_load_store/host-mem-barrier, by using the GPU to do uploads, exposing a st/mesa issue where it doesn't give us memory_barrier() calls. This is a pre-existing issue and will be fixed by a later patch (currently out for review).