re PR c++/14179 (out of memory while parsing array with many initializers)

2017-02-02  Richard Biener  <rguenther@suse.de>

	PR cp/14179
	* cp-gimplify.c (cp_fold): When folding a CONSTRUCTOR copy
	it lazily on the first changed element only and copy it
	fully upfront, only storing changed elements.

From-SVN: r245118

gcc/cp/ChangeLog

+2017-02-02  Richard Biener  <rguenther@suse.de>
+
+	PR cp/14179
+	* cp-gimplify.c (cp_fold): When folding a CONSTRUCTOR copy
+	it lazily on the first changed element only and copy it
+	fully upfront, only storing changed elements.
+
 2017-02-02  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	PR c++/69637

gcc/cp/cp-gimplify.c

@@ -2358,30 +2358,26 @@ cp_fold (tree x)
       {
 	unsigned i;
 	constructor_elt *p;
-	bool changed = false;
 	vec<constructor_elt, va_gc> *elts = CONSTRUCTOR_ELTS (x);
 	vec<constructor_elt, va_gc> *nelts = NULL;
-	vec_safe_reserve (nelts, vec_safe_length (elts));
 	FOR_EACH_VEC_SAFE_ELT (elts, i, p)
 	  {
 	    tree op = cp_fold (p->value);
-	    constructor_elt e = { p->index, op };
-	    nelts->quick_push (e);
 	    if (op != p->value)
 	      {
 		if (op == error_mark_node)
 		  {
 		    x = error_mark_node;
-		    changed = false;
+		    vec_free (nelts);
 		    break;
 		  }
-		changed = true;
+		if (nelts == NULL)
+		  nelts = elts->copy ();
+		(*nelts)[i].value = op;
 	      }
 	  }
-	if (changed)
+	if (nelts)
 	  x = build_constructor (TREE_TYPE (x), nelts);
-	else
-	  vec_free (nelts);
 	break;
       }
     case TREE_VEC: