[Bug target/115950] Missed SVE fold to INCP

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115950

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |aarch64-sve
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2024-07-16

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed.

Failed to match this instruction:
(set (reg:DI 104 [ _4 ])
    (plus:DI (zero_extend:DI (unspec:SI [
                    (reg:VNx16BI 106)
                    (const_int 0 [0])
                    (reg:VNx16BI 106)
                ] UNSPEC_CNTP))
        (reg:DI 105)))



We have:
;; Increment an SImode register by the number of set bits in a predicate
;; using modular arithmetic.  See aarch64_sve_cntp for a description of
;; the operands.
(define_insn_and_rewrite "*aarch64_incsi<mode>_cntp"
  [(set (match_operand:SI 0 "register_operand" "=r")
        (plus:SI
          (unspec:SI [(match_operand 3)
                      (const_int SVE_KNOWN_PTRUE)
                      (match_operand:PRED_ALL 2 "register_operand" "Upa")]
                     UNSPEC_CNTP)
          (match_operand:SI 1 "register_operand" "0")))]
  "TARGET_SVE"
  "incp\t%x0, %2.<Vetype>"
  "&& !CONSTANT_P (operands[3])"
  {
    operands[3] = CONSTM1_RTX (<MODE>mode);
  }
)


But not the zero_extend pattern.

Should not be hard to add. maybe sign_extend is also needed.

Due to this:
```
using s64 = int64_t;

s64 foo3(s64 x, svbool_t pg)
{
  return x+(signed char)svcntp_b8(pg, pg);
}
```

Which gives:
Failed to match this instruction:
(set (reg:DI 106 [ _6 ])
    (plus:DI (sign_extend:DI (subreg:QI (unspec:SI [
                        (reg:VNx16BI 109)
                        (const_int 0 [0])
                        (reg:VNx16BI 109)
                    ] UNSPEC_CNTP) 0))
        (reg:DI 108)))