intel/fs: Add workgroup_size() helper

Reviewed-by: Francisco Jerez <currojerez@riseup.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3226>

src/intel/compiler/brw_fs.cpp

@@ -8721,3 +8721,11 @@ brw_fs_test_dispatch_packing(const fs_builder &bld)
       set_predicate(BRW_PREDICATE_NORMAL, bld.emit(BRW_OPCODE_WHILE));
    }
 }
+
+unsigned
+fs_visitor::workgroup_size() const
+{
+   assert(stage == MESA_SHADER_COMPUTE);
+   const struct brw_cs_prog_data *cs = brw_cs_prog_data(prog_data);
+   return cs->local_size[0] * cs->local_size[1] * cs->local_size[2];
+}

src/intel/compiler/brw_fs.h

@@ -411,6 +411,8 @@ private:
    void lower_mul_dword_inst(fs_inst *inst, bblock_t *block);
    void lower_mul_qword_inst(fs_inst *inst, bblock_t *block);
    void lower_mulh_inst(fs_inst *inst, bblock_t *block);
+
+   unsigned workgroup_size() const;
 };
 
 /**