如何使用GCC產生C/Assembly Interleavd Output

提問於cszone, LCamel透過google在djgpp的網站找到解法:
gcc -c -g -Wa,-a,-ad test.c

這個方法相當巧妙, 原理是利用 -g 產生 C source level debug symbols,
再透過 -Wa 把 -a -ad 傳給 gnu assembler, 其中:
-a requests high-level, assembly, and symbols listing.
-ad omits debugging directives from the listing.

亦可搭配-O2或-O3使用, 觀察optimized的code.

test.c:

int foo(int a) {       
   if (a==1)
     return 1;
   return a*foo(a-1);
}
  

輸出結果:

ARM GAS  /tmp/ccc0kCsW.s                        page 1


   1                    @ Generated by gcc 2.95.2 19991024 (release) for ARM/elf
   2                            .file   "test.c"
   5                    .text
   6                    .Ltext0:
  27                            .align  2
  30                            .global foo
  32                    foo:
   1:test.c        **** int foo(int a) {
  34                    .LM1:
  35                            @ args = 0, pretend = 0, frame = 4
  36                            @ frame_needed = 1, current_function_anonymous_args = 0
  37 0000 0DC0A0E1              mov     ip, sp
  38 0004 00D82DE9              stmfd   sp!, {fp, ip, lr, pc}
  39 0008 04B04CE2              sub     fp, ip, #4
  40 000c 04D04DE2              sub     sp, sp, #4
  41 0010 10000BE5              str     r0, [fp, #-16]
   2:test.c        ****    if (a==1)
  43                    .LM2:
  44 0014 10301BE5              ldr     r3, [fp, #-16]
  45 0018 010053E3              cmp     r3, #1
  46 001c 0800001A              bne     .L3
   3:test.c        ****      return 1;
  48                    .LM3:
  49 0020 0100A0E3              mov     r0, #1
  50 0024 110000EA              b       .L2
  51                    .L3:
   4:test.c        ****    return a*foo(a-1);
  53                    .LM4:
  54 0028 10201BE5              ldr     r2, [fp, #-16]
  55 002c 013042E2              sub     r3, r2, #1
  56 0030 0300A0E1              mov     r0, r3
  57 0034 FEFFFFEB              bl      foo
  58 0038 0030A0E1              mov     r3, r0
  59 003c 10201BE5              ldr     r2, [fp, #-16]
  60 0040 920303E0              mul     r3, r2, r3
  61 0044 0300A0E1              mov     r0, r3
  62 0048 110000EA              b       .L2
   5:test.c        **** }
  64                    .LM5:
  65                    .L2:
  66 004c 00A81BE9              ldmea   fp, {fp, sp, pc}
  67                    .Lfe1:
  69                    .Lscope0:
  71                            .text
  73                    .Letext:
  74                            .ident  "GCC: (GNU) 2.95.2 19991024 (release)"

ARM GAS  /tmp/ccc0kCsW.s                        page 2


DEFINED SYMBOLS
                            *ABS*:00000000 test.c
     /tmp/ccc0kCsW.s:32     .text:00000000 foo

NO UNDEFINED SYMBOLS