20030414-1.c

this is a gcc file, you can download it and learn its usetility, for further detail please look at t

/* PR target/10377
   Distilled by Hans-Peter Nilsson <[e-mail]> from ncurses-5.3 infocmp.c.
   Copyright (C) 2003 Free Software Foundation.  */

/* { dg-do assemble } */
/* { dg-options "-O2 -fPIC" { target *-*-*gnu* } } */

extern int f2 (char *, char *);
extern char *ss[];
extern char *cc;
void
f1 (char *dd, char *bb)
{
  char *sp = bb + 1;
  char *ap;
  int i;
  char *ee = 0;
  char *cp;

  for (i = 0, cp = cc; i < 42; i++)
    if (cp)
      {
	if (f2 (dd, "xx") || f2 (ss[i], "xx") || f2 (ss[i], "yy"))
	  if (bb < cp)
	    continue;
	ee = ss[i];
	break;
      }

  if (!ee)
    for (ap = cc; *ap; ap++)
      if (f2(ap, sp))
	{
	  ee = ap;
	  break;
	}

  cc = ee;
}