> бесполезные и ненужные технологии, которым место в анналах истории?

И правда зачем нужны бесполезные дубы, если есть желуди?

https://github.com/gcc-mirror/gcc/blob/master/gcc/common.md

;; Common GCC machine description file, shared by all targets.
...
(define_constraint "V"
  "Matches a non-offsettable memory reference."
  (and (match_code "mem")
       (match_test "memory_address_addr_space_p (GET_MODE (op), XEXP (op, 0),
                         MEM_ADDR_SPACE (op))")
       (not (match_test "offsettable_nonstrict_memref_p (op)"))))

https://github.com/gcc-mirror/gcc/blob/master/gcc/match.pd

#if GIMPLE
/* Optimize (X + (X >> (prec - 1))) ^ (X >> (prec - 1)) into abs (X).  */
(simplify
 (bit_xor:c (plus:c @0 (rshift@2 @0 INTEGER_CST@1)) @2)
 (if (ANY_INTEGRAL_TYPE_P (TREE_TYPE (@0))
      && !TYPE_UNSIGNED (TREE_TYPE (@0))
      && wi::to_widest (@1) == element_precision (TREE_TYPE (@0)) - 1)
  (abs @0)))
#endif