There are lots of intermediate code generating between Erlang source code and byte code. These steps are as follows.

FromSourceToByteCode

* Erlang Source Code
   * Scanning
   * Parsing
   * Parse Trasform
   * Linter
* Erlang AST ('P')
* Erlang Expanded AST ('E')
* Core Erlang
* Core Erlang AST
* Kernel Erlang
* Byte Code / BEAM Code / Assember Code ('S')

Note: Using compile:file(module_name, [time]), we can see the detailed steps of compiling Erlang source code to byte code.

1> compile:file(foo, time).
Compiling foo
 remove_file                   :       0.00 s       0.6 kB
 parse_module                  :       0.00 s       1.3 kB
 transform_module              :       0.00 s       1.3 kB
 lint_module                   :       0.00 s       1.3 kB
 expand_module                 :       0.00 s       2.0 kB
 core_module                   :       0.00 s       9.6 kB
 core_fold_module              :       0.00 s       4.9 kB
 core_transforms               :       0.00 s       4.9 kB
 core_dsetel_module            :       0.00 s       4.9 kB
 kernel_module                 :       0.00 s       6.4 kB
 v3_life                       :       0.00 s       4.9 kB
 v3_codegen                    :       0.00 s       3.0 kB
 beam_a                        :       0.00 s       2.7 kB
 beam_block                    :       0.00 s       3.2 kB
 beam_except                   :       0.00 s       3.2 kB
 beam_bool                     :       0.00 s       3.2 kB
 beam_type                     :       0.00 s       3.2 kB
 beam_split                    :       0.00 s       3.1 kB
 beam_dead                     :       0.00 s       3.2 kB
 beam_jump                     :       0.00 s       3.2 kB
 beam_peep                     :       0.00 s       3.2 kB
 beam_clean                    :       0.00 s       3.2 kB
 beam_bsm                      :       0.00 s       3.2 kB
 beam_receive                  :       0.00 s       3.2 kB
 beam_trim                     :       0.00 s       3.2 kB
 beam_flatten                  :       0.00 s       2.7 kB
 beam_z                        :       0.00 s       2.7 kB
 beam_validator                :       0.00 s       2.7 kB
 beam_asm                      :       0.00 s       0.6 kB
 save_binary                   :       0.00 s       0.6 kB
{ok,foo}