gengtype: remove "tree_exp" special attribute

The function comment for adjust_field_tree_exp says this attribute is
for handling expression trees whose operands may contain pointers to RTL
instead of to trees.  But ever since r0-59671-gac45df5dba5804, which
fixed/removed the last two tree codes for which this was possible
(WITH_CLEANUP_EXPR and GOTO_SUBROUTINE_EXPR), this special attribute is
mostly a no-op.

This patch removes it and instead just annotates struct tree_exp
with the "length" attribute directly.  Not sure it makes a difference,
but I use %h instead of %0 in the attribute string to be consistent with
the other uses of the "length" attribute within tree-core.h.

This changes the code generated for TS_EXP handling in gt-cp-tree.h from:

  case TS_EXP:
    gt_ggc_m_9tree_node ((*x).generic.exp.typed.type);
    switch ((int) (TREE_CODE ((tree) &(*x))))
      {
      default:
	{
	  size_t i3;
	  size_t l3 = (size_t)(TREE_OPERAND_LENGTH ((tree) &(*x)));
	  for (i3 = 0; i3 != l3; i3++) {
	    gt_ggc_m_9tree_node ((*x).generic.exp.operands[i3]);
	  }
	}
	break;
      }
    break;

to:

  case TS_EXP:
    {
      size_t l3 = (size_t)(TREE_OPERAND_LENGTH ((tree)&((*x).generic.exp)));
      gt_ggc_m_9tree_node ((*x).generic.exp.typed.type);
      {
	size_t i3;
	for (i3 = 0; i3 != l3; i3++) {
	  gt_ggc_m_9tree_node ((*x).generic.exp.operands[i3]);
	}
      }
    }

which seems equivalent and simpler.

gcc/ChangeLog:

	* gengtype.cc (adjust_field_tree_exp): Remove.
	(adjust_field_type): Don't handle the "tree_exp" special attribute.
	* tree-core.h (struct tree_exp): Remove "special" and "desc"
	attributes.  Add "length" attribute.

2 files changed, 2 insertions, 37 deletions

diff --git a/gcc/gengtype.cc b/gcc/gengtype.cc
index 386ae1b..793ebd7 100644
--- a/gcc/gengtype.cc
+++ b/gcc/gengtype.cc
@@ -511,7 +511,6 @@ pair_p typedefs = NULL;
 type_p structures = NULL;
 pair_p variables = NULL;
 
-static type_p adjust_field_tree_exp (type_p t, options_p opt);
 static type_p adjust_field_rtx_def (type_p t, options_p opt);
 
 /* Define S as a typedef to T at POS.  */
@@ -1384,36 +1383,6 @@ adjust_field_rtx_def (type_p t, options_p ARG_UNUSED (opt))
 			nodot, NULL);
 }
 
-/* Handle `special("tree_exp")'.  This is a special case for
-   field `operands' of struct tree_exp, which although it claims to contain
-   pointers to trees, actually sometimes contains pointers to RTL too.
-   Passed T, the old type of the field, and OPT its options.  Returns
-   a new type for the field.  */
-
-static type_p
-adjust_field_tree_exp (type_p t, options_p opt ATTRIBUTE_UNUSED)
-{
-  pair_p flds;
-  options_p nodot;
-
-  if (t->kind != TYPE_ARRAY)
-    {
-      error_at_line (&lexer_line,
-		     "special `tree_exp' must be applied to an array");
-      return &string_type;
-    }
-
-  nodot = create_string_option (NULL, "dot", "");
-
-  flds = create_field (NULL, t, "");
-  flds->opt = create_string_option (nodot, "length",
-				    "TREE_OPERAND_LENGTH ((tree) &%0)");
-  flds->opt = create_string_option (flds->opt, "default", "");
-
-  return new_structure ("tree_exp_subunion", TYPE_UNION, &lexer_line, flds,
-			nodot, NULL);
-}
-
 /* Perform any special processing on a type T, about to become the type
    of a field.  Return the appropriate type for the field.
    At present:
@@ -1447,9 +1416,7 @@ adjust_field_type (type_p t, options_p opt)
 	     && opt->kind == OPTION_STRING)
       {
 	const char *special_name = opt->info.string;
-	if (strcmp (special_name, "tree_exp") == 0)
-	  t = adjust_field_tree_exp (t, opt);
-	else if (strcmp (special_name, "rtx_def") == 0)
+	if (strcmp (special_name, "rtx_def") == 0)
 	  t = adjust_field_rtx_def (t, opt);
 	else
 	  error_at_line (&lexer_line, "unknown special `%s'", special_name);
diff --git a/gcc/tree-core.h b/gcc/tree-core.h
index f1c2b64..07e76e6 100644
--- a/gcc/tree-core.h
+++ b/gcc/tree-core.h
@@ -1563,9 +1563,7 @@ enum omp_clause_linear_kind
 struct GTY(()) tree_exp {
   struct tree_typed typed;
   location_t locus;
-  tree GTY ((special ("tree_exp"),
-	     desc ("TREE_CODE ((tree) &%0)")))
-    operands[1];
+  tree GTY ((length ("TREE_OPERAND_LENGTH ((tree)&%h)"))) operands[1];
 };
 
 /* Immediate use linking structure.  This structure is used for maintaining