File: fcall.c

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/********************************************
fcall.c
copyright 1991, Michael D. Brennan

This is a source file for mawk, an implementation of
the AWK programming language.

Mawk is distributed without warranty under the terms of
the GNU General Public License, version 2, 1991.
********************************************/


/*$Log: fcall.c,v $
 * Revision 1.7  1995/08/27  15:46:47  mike
 * change some errmsgs to compile_errors
 *
 * Revision 1.6  1995/06/09  22:58:24  mike
 * cast to shutup solaris cc on comparison of short to ushort
 *
 * Revision 1.5  1995/06/06  00:18:26  mike
 * change mawk_exit(1) to mawk_exit(2)
 *
 * Revision 1.4  1995/04/21  14:20:14  mike
 * move_level variable to fix bug in arglist patching of moved code.
 *
 * Revision 1.3  1995/02/19  22:15:37  mike
 * Always set the call_offset field in a CA_REC (for obscure
 * reasons in fcall.c (see comments) there.)
 *
 * Revision 1.2  1993/07/17  13:22:52  mike
 * indent and general code cleanup
 *
 * Revision 1.1.1.1  1993/07/03	 18:58:11  mike
 * move source to cvs
 *
 * Revision 5.4	 1993/01/09  19:03:44  mike
 * code_pop checks if the resolve_list needs relocation
 *
 * Revision 5.3	 1993/01/07  02:50:33  mike
 * relative vs absolute code
 *
 * Revision 5.2	 1993/01/01  21:30:48  mike
 * split new_STRING() into new_STRING and new_STRING0
 *
 * Revision 5.1	 1991/12/05  07:55:54  brennan
 * 1.1 pre-release
 *
*/

#include "mawk.h"
#include "symtype.h"
#include "code.h"

/* This file has functions involved with type checking of
   function calls
*/

static FCALL_REC *PROTO(first_pass, (FCALL_REC *)) ;
static CA_REC *PROTO(call_arg_check, (FBLOCK *, CA_REC *,
				      INST *, unsigned)) ;
static int PROTO(arg_cnt_ok, (FBLOCK *, CA_REC *, unsigned)) ;
static void PROTO(relocate_arglist, (CA_REC *, int, unsigned, int)) ;


static int check_progress ;
 /* flag that indicates call_arg_check() was able to type
       check some call arguments */

/* type checks a list of call arguments,
   returns a list of arguments whose type is still unknown
*/
static CA_REC *
call_arg_check(callee, entry_list, start, line_no)
   FBLOCK *callee ;
   CA_REC *entry_list ;
   INST *start ;		 /* to locate patch */
   unsigned line_no ;		 /* for error messages */
{
   register CA_REC *q ;
   CA_REC *exit_list = (CA_REC *) 0 ;

   check_progress = 0 ;

   /* loop :
       take q off entry_list
       test it
	   if OK  zfree(q)  else put on exit_list  */  
   while (q = entry_list)
   {
      entry_list = q->link ;

      if (q->type == ST_NONE)
      {
	 /* try to infer the type */
	 /* it might now be in symbol table */
	 if (q->sym_p->type == ST_VAR)
	 {
	    /* set type and patch */
	    q->type = CA_EXPR ;
	    start[q->call_offset + 1].ptr = (PTR) q->sym_p->stval.cp ;
	 }
	 else if (q->sym_p->type == ST_ARRAY)
	 {
	    q->type = CA_ARRAY ;
	    start[q->call_offset].op = A_PUSHA ;
	    start[q->call_offset + 1].ptr = (PTR) q->sym_p->stval.array ;
	 }
	 else  /* try to infer from callee */
	 {
	    switch (callee->typev[q->arg_num])
	    {
	       case ST_LOCAL_VAR:
		  q->type = CA_EXPR ;
		  q->sym_p->type = ST_VAR ;
		  q->sym_p->stval.cp = ZMALLOC(CELL) ;
		  q->sym_p->stval.cp->type = C_NOINIT ;
		  start[q->call_offset + 1].ptr =
		     (PTR) q->sym_p->stval.cp ;
		  break ;

	       case ST_LOCAL_ARRAY:
		  q->type = CA_ARRAY ;
		  q->sym_p->type = ST_ARRAY ;
		  q->sym_p->stval.array = new_ARRAY() ;
		  start[q->call_offset].op = A_PUSHA ;
		  start[q->call_offset + 1].ptr =
		     (PTR) q->sym_p->stval.array ;
		  break ;
	    }
	 }
      }
      else if (q->type == ST_LOCAL_NONE)
      {
	 /* try to infer the type */
	 if (*q->type_p == ST_LOCAL_VAR)
	 {
	    /* set type , don't need to patch */
	    q->type = CA_EXPR ;
	 }
	 else if (*q->type_p == ST_LOCAL_ARRAY)
	 {
	    q->type = CA_ARRAY ;
	    start[q->call_offset].op = LA_PUSHA ;
	    /* offset+1 op is OK */
	 }
	 else  /* try to infer from callee */
	 {
	    switch (callee->typev[q->arg_num])
	    {
	       case ST_LOCAL_VAR:
		  q->type = CA_EXPR ;
		  *q->type_p = ST_LOCAL_VAR ;
		  /* do not need to patch */
		  break ;

	       case ST_LOCAL_ARRAY:
		  q->type = CA_ARRAY ;
		  *q->type_p = ST_LOCAL_ARRAY ;
		  start[q->call_offset].op = LA_PUSHA ;
		  break ;
	    }
	 }
      }

      /* if we still do not know the type put on the new list
       else type check */
      if (q->type == ST_NONE || q->type == ST_LOCAL_NONE)
      {
	 q->link = exit_list ;
	 exit_list = q ;
      }
      else  /* type known */
      {
	 if (callee->typev[q->arg_num] == ST_LOCAL_NONE)
	    callee->typev[q->arg_num] = q->type ;
	 else if (q->type != callee->typev[q->arg_num])
	    compile_error("type error in arg(%d) in call to %s",
		     q->arg_num + 1, callee->name) ;

	 ZFREE(q) ;
	 check_progress = 1 ;
      }
   }				/* while */

   return exit_list ;
}


static int
arg_cnt_ok(fbp, q, line_no)
   FBLOCK *fbp ;
   CA_REC *q ;
   unsigned line_no ;
{
   if ((int)q->arg_num >= (int)fbp->nargs)
   /* casts shutup stupid warning from solaris sun cc */
   {
      compile_error("too many arguments in call to %s", fbp->name) ;
      return 0 ;
   }
   else	 return 1 ;
}


FCALL_REC *resolve_list ;
 /* function calls whose arg types need checking
	   are stored on this list */


/* on first pass thru the resolve list
   we check :
      if forward referenced functions were really defined
      if right number of arguments
   and compute call_start which is now known
*/

static FCALL_REC *
first_pass(p)
   register FCALL_REC *p ;
{
   FCALL_REC dummy ;
   register FCALL_REC *q = &dummy ;	 /* trails p */

   q->link = p ;
   while (p)
   {
      if (!p->callee->code)
      {
	 /* callee never defined */
	 compile_error("function %s never defined", p->callee->name) ;
	 /* delete p from list */
	 q->link = p->link ;
	 /* don't worry about freeing memory, we'll exit soon */
      }
      /* note p->arg_list starts with last argument */
      else if (!p->arg_list /* nothing to do */	 ||
	       !p->arg_cnt_checked &&
	       !arg_cnt_ok(p->callee, p->arg_list, p->line_no))
      {
	 q->link = p->link ;	 /* delete p */
	 /* the ! arg_list case is not an error so free memory */
	 ZFREE(p) ;
      }
      else
      {
	 /* keep p and set call_start */
	 q = p ;
	 switch (p->call_scope)
	 {
	    case SCOPE_MAIN:
	       p->call_start = main_start ;
	       break ;

	    case SCOPE_BEGIN:
	       p->call_start = begin_start ;
	       break ;

	    case SCOPE_END:
	       p->call_start = end_start ;
	       break ;

	    case SCOPE_FUNCT:
	       p->call_start = p->call->code ;
	       break ;
	 }
      }
      p = q->link ;
   }
   return dummy.link ;
}

/* continuously walk the resolve_list making type deductions
   until this list goes empty or no more progress can be made
   (An example where no more progress can be made is at end of file
*/

void
resolve_fcalls()
{
   register FCALL_REC *p, *old_list, *new_list ;
   int progress ;		 /* a flag */

   old_list = first_pass(resolve_list) ;
   new_list = (FCALL_REC *) 0 ;
   progress = 0 ;

   while (1)
   {
      if (!old_list)
      {
	 /* flop the lists */
	 old_list = new_list ;
	 if (!old_list		/* nothing left */
	     || !progress /* can't do any more */ )
	    return ;

	 new_list = (FCALL_REC *) 0 ;  progress = 0 ;
      }

      p = old_list ;
      old_list = p->link ;

      if (p->arg_list = call_arg_check(p->callee, p->arg_list,
				       p->call_start, p->line_no))
      {
	 /* still have work to do , put on new_list   */
	 progress |= check_progress ;
	 p->link = new_list ;  new_list = p ;
      }
      else
      {
	 /* done with p */
	 progress = 1 ;
	 ZFREE(p) ;
      }
   }
}

/* the parser has just reduced a function call ;
   the info needed to type check is passed in.	If type checking
   can not be done yet (most common reason -- function referenced
   but not defined), a node is added to the resolve list.
*/
void
check_fcall(callee, call_scope, move_level, call, arg_list, line_no)
   FBLOCK *callee ;
   int call_scope ;
   int move_level ;
   FBLOCK *call ;
   CA_REC *arg_list ;
   unsigned line_no ;
{
   FCALL_REC *p ;

   if (!callee->code)
   {
      /* forward reference to a function to be defined later */
      p = ZMALLOC(FCALL_REC) ;
      p->callee = callee ;
      p->call_scope = call_scope ;
      p->move_level = move_level ;
      p->call = call ;
      p->arg_list = arg_list ;
      p->arg_cnt_checked = 0 ;
      p->line_no = line_no ;
      /* add to resolve list */
      p->link = resolve_list ; resolve_list = p ;
   }
   else if (arg_list && arg_cnt_ok(callee, arg_list, line_no))
   {
      /* usually arg_list disappears here and all is well
	 otherwise add to resolve list */

      if (arg_list = call_arg_check(callee, arg_list,
				    code_base, line_no))
      {
	 p = ZMALLOC(FCALL_REC) ;
	 p->callee = callee ;
	 p->call_scope = call_scope ;
	 p->move_level = move_level ;
	 p->call = call ;
	 p->arg_list = arg_list ;
	 p->arg_cnt_checked = 1 ;
	 p->line_no = line_no ;
	 /* add to resolve list */
	 p->link = resolve_list ; resolve_list = p ;
      }
   }
}


/* code_pop() has just moved some code.	 If this code contains
   a function call, it might need to be relocated on the
   resolve list too.  This function does it.
*/

void
relocate_resolve_list(scope, move_level, fbp, orig_offset, len, delta)
   int scope ;
   int move_level ;
   FBLOCK *fbp ;
   int orig_offset ;
   unsigned len ;
   int delta ;			 /* relocation distance */
{
   FCALL_REC *p = resolve_list ;

   while (p)
   {
      if (scope == p->call_scope && move_level == p->move_level &&
	  (scope == SCOPE_FUNCT ? fbp == p->call : 1))
      {
	 relocate_arglist(p->arg_list, orig_offset,
			  len, delta) ;
      }
      p = p->link ;
   }
}

static void
relocate_arglist(arg_list, offset, len, delta)
   CA_REC *arg_list ;
   int offset ;
   unsigned len ;
   int delta ;
{
   register CA_REC *p ;

   if (!arg_list)  return ;

   p = arg_list ;
   /* all nodes must be relocated or none, so test the
     first one */

   /* Note: call_offset is always set even for args that don't need to
      be patched so that this check works. */
   if ( p->call_offset < offset || p->call_offset >= offset + len )
      return ;

   /* relocate the whole list */
   do
   {
      p->call_offset += delta ;
      p = p->link ;
   }
   while (p);
}





/*  example where typing cannot progress

{ f(z) }

function f(x) { print NR }

# this is legal, does something useful, but absurdly written
# We have to design so this works
*/