Bryand and O'Hallaron
                            Chapter 3 Section 3.6.4
                           Translating if Statements



ironman:~/bando/chap3/sec6>more sec364.c
int absdiff(int x, int y)
{
    if (x < y)
        return y-x;
    else
        return x - y;
}


ironman:~/bando/chap3/sec6>gcc -S -O2 sec364.c
ironman:~/bando/chap3/sec6>more sec364.s
...
absdiff:
        pushl   %ebp
        movl    %esp, %ebp
        movl    8(%ebp), %edx     # x
        movl    12(%ebp), %eax    # y
        cmpl    %eax, %edx
        jge     .L2               # jump if %edx >= %eax
        popl    %ebp
        subl    %edx, %eax
        ret
        .p2align 4,,7
.L2:
        popl    %ebp
        subl    %eax, %edx
        movl    %edx, %eax
        ret

Bryant & O'Halloran Compiler

...
absdiff:
        pushl   %ebp
        movl    %esp, %ebp
        movl    8(%ebp), %edx     # x
        movl    12(%ebp), %eax    # y
        cmpl    %eax, %edx
        jl      .L3               # jump if %edx < %eax
        subl    %eax, %edx        # x - y
        movl    %edx, %eax
        jmp     .L5
.L3:
        subl    %edx, %eax        # y - x
.L5
        popl    %ebp
        ret


int absdiff(int x, int y)
{
      int rval;
      if (x < y)
	      goto less;
      rval = y-x;
      goto done;
less:
      rval =  y - x;
done:
      return rval;
}