bi: Use nir_opt_load_store_vectorize

Ensure we vectorize load/store when possible.
Also move lower pack after loop optimization.

This drastically reduce the shader size of
"dEQP-VK.graphicsfuzz.spv-stable-maze-flatten-copy-composite" and allow
it to pass instead of timing out but it might greatly help others.

Signed-off-by: Mary Guillemard <mary.guillemard@collabora.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/30484>

src/panfrost/compiler/bifrost_compile.c

@@ -4530,11 +4530,28 @@ mem_access_size_align_cb(nir_intrinsic_op intrin, uint8_t bytes,
    };
 }
 
+static bool
+mem_vectorize_cb(unsigned align_mul, unsigned align_offset, unsigned bit_size,
+                 unsigned num_components, nir_intrinsic_instr *low,
+                 nir_intrinsic_instr *high, void *data)
+{
+   /* Must be aligned to the size of the load */
+   unsigned align = nir_combined_align(align_mul, align_offset);
+   if ((bit_size / 8) > align)
+      return false;
+
+   if (num_components > 4)
+      return false;
+
+   if (bit_size > 32)
+      return false;
+
+   return true;
+}
+
 static void
 bi_optimize_nir(nir_shader *nir, unsigned gpu_id, bool is_blend)
 {
-   NIR_PASS(_, nir, nir_lower_pack);
-
    bool progress;
 
    do {
@@ -4559,6 +4576,14 @@ bi_optimize_nir(nir_shader *nir, unsigned gpu_id, bool is_blend)
       NIR_PASS(progress, nir, nir_opt_loop_unroll);
    } while (progress);
 
+   NIR_PASS(
+      progress, nir, nir_opt_load_store_vectorize,
+      &(const nir_load_store_vectorize_options){
+         .modes = nir_var_mem_global | nir_var_mem_shared | nir_var_shader_temp,
+         .callback = mem_vectorize_cb,
+      });
+   NIR_PASS(progress, nir, nir_lower_pack);
+
    /* TODO: Why is 64-bit getting rematerialized?
     * KHR-GLES31.core.shader_image_load_store.basic-allTargets-atomicFS */
    NIR_PASS(progress, nir, nir_lower_int64);