[Bug target/77308] surprisingly large stack usage for sha512 on arm

[bernd.edlinger at hotmail dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77308

--- Comment #40 from Bernd Edlinger <bernd.edlinger at hotmail dot de> ---
BTW: I found something strange in this pattern in neon.md:

(define_insn_and_split "orndi3_neon"
  [(set (match_operand:DI 0 "s_register_operand" "=w,?&r,?&r,?&r")
        (ior:DI (not:DI (match_operand:DI 2 "s_register_operand" "w,0,0,r"))
                (match_operand:DI 1 "s_register_operand" "w,r,r,0")))]
  "TARGET_NEON"
  "@
   vorn\t%P0, %P1, %P2
   #
   #
   #"
  "reload_completed && 
   (TARGET_NEON && !(IS_VFP_REGNUM (REGNO (operands[0]))))"
  [(set (match_dup 0) (ior:SI (not:SI (match_dup 2)) (match_dup 1)))
   (set (match_dup 3) (ior:SI (not:SI (match_dup 4)) (match_dup 5)))]
  "
  {
    if (TARGET_THUMB2)
      {
        operands[3] = gen_highpart (SImode, operands[0]);
        operands[0] = gen_lowpart (SImode, operands[0]);
        operands[4] = gen_highpart (SImode, operands[2]);
        operands[2] = gen_lowpart (SImode, operands[2]);
        operands[5] = gen_highpart (SImode, operands[1]);
        operands[1] = gen_lowpart (SImode, operands[1]);
      }
    else
      {
        emit_insn (gen_one_cmpldi2 (operands[0], operands[2]));
        emit_insn (gen_iordi3 (operands[0], operands[1], operands[0]));
        DONE;
      }
  }"
  [(set_attr "type" "neon_logic,multiple,multiple,multiple")
   (set_attr "length" "*,16,8,8")
   (set_attr "arch" "any,a,t2,t2")]
)


I think in alternative#4 we have operands[0] == operands[1]
and operands[2] != operands[0]

and then gen_one_cmpldi2 (operands[0], operands[2])
will overwrite the operand[1] before it is used in
gen_iordi3 (operands[0], operands[1], operands[0]) ??