c-iterate.c

GCC编译器源代码

  expand_start_loop_continue_elsewhere (1);

  ITERATOR_BOUND_P (idecl) = 1;

  if (end_note)
    *end_note = emit_note (0, NOTE_INSN_DELETED);
}

/* Similar to the previous function, but for the end of the loop.

   DECL_RTL is zeroed unless we are inside "({...})". The reason for that is
   described below.

   When we create two (or more) loops based on the same IDECL, and
   both inside the same "({...})"  construct, we must be prepared to
   delete both of the loops and create a single one on the level
   above, i.e.  enclosing the "({...})". The new loop has to use the
   same counter rtl because the references to the iterator decl
   (IDECL) have already been expanded as references to the counter
   rtl.

   It is incorrect to use the same counter reg in different functions,
   and it is desirable to use different counters in disjoint loops
   when we know there's no need to combine them (because then they can
   get allocated separately).  */

static void
iterator_loop_epilogue (idecl, start_note, end_note)
     tree idecl;
     rtx *start_note, *end_note;
{
  tree test, incr;

  if (start_note)
    *start_note = emit_note (0, NOTE_INSN_DELETED);
  expand_loop_continue_here ();
  incr = build_binary_op (PLUS_EXPR, idecl, integer_one_node, 0);
  incr = build (MODIFY_EXPR, TREE_TYPE (idecl), idecl, incr);
  TREE_SIDE_EFFECTS (incr) = 1;
  expand_expr (incr, const0_rtx, VOIDmode, 0);
  test = build_binary_op (LT_EXPR, idecl, DECL_INITIAL (idecl), 0);
  expand_exit_loop_if_false (0, test);
  expand_end_loop ();

  ITERATOR_BOUND_P (idecl) = 0;
  /* we can reset rtl since there is not chance that this expansion */
  /* would be superseded by a higher level one */
  /* but don't do this if the decl is static, since we need to share */
  /* the same decl in that case.  */
  if (top_level_ixpansion_p () && ! TREE_STATIC (idecl))
    DECL_RTL (idecl) = 0;
  if (end_note)
    *end_note = emit_note (0, NOTE_INSN_DELETED);
}

/* Return true if we are not currently inside a "({...})" construct.  */

static int
top_level_ixpansion_p ()
{
  return iter_stack == 0;
}

/* Given two chains of iter_stack_nodes,
   append the nodes in X into Y.  */

static void
isn_append (x, y)
     struct iter_stack_node *x, *y;
{
  if (x->first == 0) 
    return;

  if (y->first == 0)
    {
      y->first = x->first;
      y->last  = x->last;
    }
  else
    {
      y->last->next = x->first;
      y->last = x->last;
    }
}

/** Make X empty **/

#define ISN_ZERO(X) (X).first=(X).last=0

/* Move the ixpansions in sublevel_ixpansions into the current
   node on the iter_stack, or discard them if the iter_stack is empty.
   We do this at the end of a statement.  */

static void
istack_sublevel_to_current ()
{
  /* At the top level we can throw away sublevel's expansions  **/
  /* because there is nobody above us to ask for a cleanup **/
  if (iter_stack != 0)
    /** Merging with empty sublevel list is a no-op **/
    if (sublevel_ixpansions.last)
      isn_append (&sublevel_ixpansions, iter_stack);

  if (iter_stack == 0)
    obstack_free (&ixp_obstack, ixp_firstobj);

  ISN_ZERO (sublevel_ixpansions);
}

/* Push a new node on the iter_stack, when we enter a ({...}).  */

void
push_iterator_stack ()
{
  struct iter_stack_node *new_top
    = (struct iter_stack_node *) 
      obstack_alloc (&ixp_obstack, sizeof (struct iter_stack_node));

  new_top->first = 0;
  new_top->last = 0;
  new_top->next = iter_stack;
  iter_stack = new_top;
}

/* Pop iter_stack, moving the ixpansions in the node being popped
   into sublevel_ixpansions.  */

void
pop_iterator_stack ()
{
  if (iter_stack == 0)
    abort ();

  isn_append (iter_stack, &sublevel_ixpansions);
  /** Pop current level node: */
  iter_stack = iter_stack->next;
}


/* Record an iterator expansion ("ixpansion") for IDECL.
   The remaining parameters are the notes in the loop entry
   and exit rtl.  */

static void
add_ixpansion (idecl, pro_start, pro_end, epi_start, epi_end)
     tree idecl;
     rtx pro_start, pro_end, epi_start, epi_end;
{
  struct ixpansion *newix;
    
  /* Do nothing if we are not inside "({...})",
     as in that case this expansion can't need subsequent RTL modification.  */
  if (iter_stack == 0)
    return;

  newix = (struct ixpansion *) obstack_alloc (&ixp_obstack,
					      sizeof (struct ixpansion));
  newix->ixdecl = idecl;
  newix->ixprologue_start = pro_start;
  newix->ixprologue_end   = pro_end;
  newix->ixepilogue_start = epi_start;
  newix->ixepilogue_end   = epi_end;

  newix->next = iter_stack->first;
  iter_stack->first = newix;
  if (iter_stack->last == 0)
    iter_stack->last = newix;
}

/* Delete the RTL for all ixpansions for iterator IDECL
   in our sublevels.  We do this when we make a larger
   containing expansion for IDECL.  */

static void
delete_ixpansion (idecl)
     tree idecl;
{
  struct ixpansion *previx = 0, *ix;

  for (ix = sublevel_ixpansions.first; ix; ix = ix->next)
    if (ix->ixdecl == idecl)
      {
	/** zero means that this is a mark for FOR -- **/
	/** we do not delete anything, just issue an error. **/

	if (ix->ixprologue_start == 0)
	  error_with_decl (idecl,
			   "`for (%s)' appears within implicit iteration");
	else
	  {
	    rtx insn;
	    /* We delete all insns, including notes because leaving loop */
	    /* notes and barriers produced by iterator expansion would */
	    /* be misleading to other phases */

	    for (insn = NEXT_INSN (ix->ixprologue_start);
		 insn != ix->ixprologue_end;
		 insn = NEXT_INSN (insn)) 
	      delete_insn (insn);
	    for (insn = NEXT_INSN (ix->ixepilogue_start);
		 insn != ix->ixepilogue_end;
		 insn = NEXT_INSN (insn)) 
	      delete_insn (insn);
	  }

	/* Delete this ixpansion from sublevel_ixpansions.  */
	if (previx)
	  previx->next = ix->next;
	else 
	  sublevel_ixpansions.first = ix->next;
	if (sublevel_ixpansions.last == ix)
	  sublevel_ixpansions.last = previx;
      }
    else
      previx = ix;
}

#ifdef DEBUG_ITERATORS

/* The functions below are for use from source level debugger.
   They print short forms of iterator lists and the iterator stack.  */

/* Print the name of the iterator D.  */

void
prdecl (d)
     tree d;
{
  if (d)
    {
      if (TREE_CODE (d) == VAR_DECL)
	{
	  tree tname = DECL_NAME (d);
	  char *dname = IDENTIFIER_POINTER (tname);
	  fprintf (stderr, dname);
	}
      else
	fprintf (stderr, "<<Not a Decl!!!>>");
    }
  else
    fprintf (stderr, "<<NULL!!>>");
}

/* Print Iterator List -- names only */

tree
pil (head)
     tree head;
{
  tree current, next;
  for (current = head; current; current = next)
    {
      tree node = TREE_VALUE (current);
      prdecl (node);
      next = TREE_CHAIN (current);
      if (next) fprintf (stderr, ",");
    }
  fprintf (stderr, "\n");
}

/* Print IXpansion List */

struct ixpansion *
pixl (head)
     struct ixpansion *head;
{
  struct ixpansion *current, *next;
  fprintf (stderr, "> ");
  if (head == 0)
    fprintf (stderr, "(empty)");
	
  for (current=head; current; current = next)
    {
      tree node = current->ixdecl;
      prdecl (node);
      next = current->next;
      if (next)
	fprintf (stderr, ",");
    }
  fprintf (stderr, "\n");
  return head;
}

/* Print Iterator Stack.  */

void
pis ()
{
  struct iter_stack_node *stack_node;

  fprintf (stderr, "--SubLevel: ");
  pixl (sublevel_ixpansions.first);
  fprintf (stderr, "--Stack:--\n");
  for (stack_node = iter_stack;
       stack_node;
       stack_node = stack_node->next)
    pixl (stack_node->first);
}

#endif /* DEBUG_ITERATORS */