prefer do_alloca over safe_emalloc

Author: jordikroon

ext/mbstring/mbstring.c

@@ -3414,16 +3414,17 @@ MBSTRING_API const mbfl_encoding* mb_guess_encoding_for_strings(const unsigned c
 		return *elist;
 	}
 
-	/* Allocate on stack; when we return, this array is automatically freed */
-	struct candidate *array = (struct candidate *) safe_emalloc(elist_size, sizeof(struct candidate), 0);
+	/* Allocate on stack or heap; when we return, this array is automatically freed */
+	ALLOCA_FLAG(use_heap)
+	struct candidate *array = do_alloca(elist_size * sizeof(struct candidate), use_heap);
 	elist_size = init_candidate_array(array, elist_size, elist, strings, str_lengths, n, strict, order_significant);
 
 	while (n--) {
 		start_string(array, elist_size, strings[n], str_lengths[n]);
 		elist_size = count_demerits(array, elist_size, strict);
 		if (elist_size == 0) {
 			/* All candidates were eliminated */
-			efree(array);
+			free_alloca(array, use_heap);
 			return NULL;
 		}
 	}
@@ -3437,7 +3438,7 @@ MBSTRING_API const mbfl_encoding* mb_guess_encoding_for_strings(const unsigned c
 	}
 
 	const mbfl_encoding *result = array[best].enc;
-	efree(array);
+	free_alloca(array, use_heap);
 	return result;
 }