i965/spirv: Lower shared memory later

Instead of asking spirv_to_nir to lower the workgroup (shared memory)
to offsets, keep them as derefs longer, then lower it later on.

Because Workgroup memory doesn't have explicit offsets, we need to set
those using nir_lower_vars_to_explicit_types before calling the I/O
lowering pass.

Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>

src/mesa/drivers/dri/i965/brw_program.c

@@ -157,6 +157,18 @@ brw_create_nir(struct brw_context *brw,
    return nir;
 }
 
+static void
+shared_type_info(const struct glsl_type *type, unsigned *size, unsigned *align)
+{
+   assert(glsl_type_is_vector_or_scalar(type));
+
+   uint32_t comp_size = glsl_type_is_boolean(type)
+      ? 4 : glsl_get_bit_size(type) / 8;
+   unsigned length = glsl_get_vector_elements(type);
+   *size = comp_size * length,
+   *align = comp_size * (length == 3 ? 4 : length);
+}
+
 void
 brw_nir_lower_resources(nir_shader *nir, struct gl_shader_program *shader_prog,
                         struct gl_program *prog,
@@ -168,6 +180,14 @@ brw_nir_lower_resources(nir_shader *nir, struct gl_shader_program *shader_prog,
 
    NIR_PASS_V(prog->nir, brw_nir_lower_image_load_store, devinfo);
 
+   if (prog->nir->info.stage == MESA_SHADER_COMPUTE &&
+       shader_prog->data->spirv) {
+      NIR_PASS_V(prog->nir, nir_lower_vars_to_explicit_types,
+                 nir_var_mem_shared, shared_type_info);
+      NIR_PASS_V(prog->nir, nir_lower_explicit_io,
+                 nir_var_mem_shared, nir_address_format_32bit_offset);
+   }
+
    NIR_PASS_V(prog->nir, gl_nir_lower_buffers, shader_prog);
    /* Do a round of constant folding to clean up address calculations */
    NIR_PASS_V(prog->nir, nir_opt_constant_folding);

src/mesa/main/glspirv.c

@@ -245,7 +245,6 @@ _mesa_spirv_to_nir(struct gl_context *ctx,
 
    const struct spirv_to_nir_options spirv_options = {
       .environment = NIR_SPIRV_OPENGL,
-      .lower_workgroup_access_to_offsets = true,
       .frag_coord_is_sysval = ctx->Const.GLSLFragCoordIsSysVal,
       .caps = ctx->Const.SpirVCapabilities,
       .ubo_addr_format = nir_address_format_32bit_index_offset,