gas/testsuite/gas/cfi/cfi-i386.s

   1 #; $ as -o test.o gas-cfi-test.s && gcc -nostdlib -o test test.o
   2
   3         .text
   4
   5 #; func_locvars
   6 #; - function with a space on the stack
   7 #;   allocated for local variables
   8
   9         .type   func_locvars,@function
  10 func_locvars:
  11         .cfi_startproc
  12
  13         #; alocate space for local vars
  14         sub     $0x1234,%esp
  15         .cfi_adjust_cfa_offset  0x1234
  16
  17         #; dummy body
  18         movl    $1,%eax
  19
  20         #; release space of local vars and return
  21         add     $0x1234,%esp
  22         .cfi_adjust_cfa_offset  -0x1234
  23         ret
  24         .cfi_endproc
  25
  26 #; func_prologue
  27 #; - functions that begins with standard
  28 #;   prologue: "pushq %rbp; movq %rsp,%rbp"
  29
  30         .type   func_prologue,@function
  31 func_prologue:
  32         .cfi_startproc
  33
  34         #; prologue, CFI is valid after
  35         #; each instruction.
  36         pushl   %ebp
  37         .cfi_def_cfa_offset     8
  38         .cfi_offset             ebp,-8
  39         movl    %esp, %ebp
  40         .cfi_def_cfa_register   ebp
  41
  42         #; function body
  43         call    func_locvars
  44         addl    $3, %eax
  45
  46         #; epilogue with valid CFI
  47         #; (we're better than gcc :-)
  48         leave
  49         .cfi_def_cfa_register   esp
  50         ret
  51         .cfi_endproc
  52
  53 #; func_otherreg
  54 #; - function that moves frame pointer to
  55 #;   another register (r12) and then allocates
  56 #;   a space for local variables
  57
  58         .type   func_otherreg,@function
  59 func_otherreg:
  60         .cfi_startproc
  61
  62         #; save frame pointer to ebx
  63         mov     %esp,%ebx
  64         .cfi_def_cfa_register   ebx
  65
  66         #; alocate space for local vars
  67         #;  (no .cfi_{def,adjust}_cfa_offset here,
  68         #;   because CFA is computed from r12!)
  69         sub     $100,%esp
  70
  71         #; function body
  72         call    func_prologue
  73         add     $2, %eax
  74
  75         #; restore frame pointer from r12
  76         mov     %ebx,%esp
  77         .cfi_def_cfa            esp,4
  78         ret
  79         .cfi_endproc
  80
  81 #; main
  82 #; - typical function
  83         .type   main,@function
  84 main:
  85         .cfi_startproc
  86
  87         #; only function body that doesn't
  88         #; touch the stack at all.
  89         call    func_otherreg
  90
  91         #; return
  92         ret
  93         .cfi_endproc
  94
  95 #; _start
  96 #; - standard entry point
  97
  98         .type   _start,@function
  99         .globl  _start
 100 _start:
 101         .cfi_startproc
 102         call    main
 103         movl    %eax,%edi
 104         movl    $0x1,%eax
 105         int     $0x80
 106         hlt
 107         .cfi_endproc