As for going further staying with the bare-bones approach, I suppose you'd have to start looking at assembly output and how that fits with what the c-code does. I don't know anything about OSX x86_64 calling conventions etc -- but at least under Linux (and afaik windows) 64bits is a lot more friendly and fun than the mess that was 32bit (and 16bit) x86.

There are a couple of great (free) resources on 32bit x86 assembly I'm aware of:

http://www.drpaulcarter.com/pcasm/ http://www.plantation-productions.com/Webster/HighLevelAsm/i...

There's apparently some plans on upgrading HLA to x86_64 -- I don't know of any good tutorials or guides on working on 64bit assembly specifically I'm afraid.

Just adding "-S" and looking at the source can be helpful of course, although I much prefer nasm/intel syntax, for clang/gcc that should require:

   clang -S -mllvm --x86-asm-syntax=intel main.c
   gcc -S -masm=intel main.c

Note that gas syntax is the "default" in the gnu-world, so it might be easier to just go with that if you're just starting out.

It looks like clang might be generating less "noise" for tiny trivial programs, here's a side by-side-diff (in intel syntax) of int main{} vs int main { return 0;} (slightly reformatted):

    diff --side-by-side main.s main.no-ret 
      .file   "main.c"                          .file   "main.c"
      .text                                     .text
      .globl  main                              .globl  main
      .align  16, 0x90                          .align  16, 0x90
      .type   main,@function                    .type   main,@function
    main:                       # @main       main:          # @main
      .cfi_startproc                            .cfi_startproc
    # BB#0:                     # %entry      # BB#0:        # %entry
      mov     EAX, 0                             mov     EAX, 0
      mov     DWORD PTR [RSP - 4], 0         <
      ret                                        ret
    .Ltmp0:                                   .Ltmp0:
      .size   main, .Ltmp0-main                 .size   main, .Ltmp0-main
      .cfi_endproc                              .cfi_endproc

      .section ".note.GNU-stack","",@progbits   .section ".note.GNU-stack","",@progbits

It can be fun to do this with stuff like hello world (and contrast puts("Hello, world!"); with printf("Hello world!\n);).