;; s390x instruction selection and CLIF-to-MachInst lowering.

;; The main lowering constructor term: takes a clif `Inst` and returns the
;; register(s) within which the lowered instruction's result values live.
(decl partial lower (Inst) InstOutput)

;; A variant of the main lowering constructor term, used for branches.
;; The only difference is that it gets an extra argument holding a vector
;; of branch targets to be used.
(decl partial lower_branch (Inst MachLabelSlice) Unit)


;;;; Rules for `iconst` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(rule (lower (has_type ty (iconst (u64_from_imm64 n))))
      (imm ty n))


;;;; Rules for `f32const` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(rule (lower (f32const (u32_from_ieee32 x)))
      (imm $F32 x))


;;;; Rules for `f64const` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(rule (lower (f64const (u64_from_ieee64 x)))
      (imm $F64 x))


;;;; Rules for `vconst` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(rule (lower (has_type ty (vconst (u128_from_constant x))))
      (vec_imm ty (be_vec_const ty x)))


;;;; Rules for `nop` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(rule (lower (nop))
      (invalid_reg))


;;;; Rules for `iconcat` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(rule (lower (has_type (vr128_ty ty) (iconcat x y)))
      (mov_to_vec128 ty y x))


;;;; Rules for `isplit` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(rule (lower (isplit x @ (value_type $I128)))
      (let ((x_reg Reg x)
            (x_hi Reg (vec_extract_lane $I64X2 x_reg 0 (zero_reg)))
            (x_lo Reg (vec_extract_lane $I64X2 x_reg 1 (zero_reg))))
        (output_pair x_lo x_hi)))


;;;; Rules for `iadd` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Add two registers.
(rule 0 (lower (has_type (fits_in_64 ty) (iadd x y)))
      (add_reg ty x y))

;; Add a register and a sign-extended register.
(rule 8 (lower (has_type (fits_in_64 ty) (iadd x (sext32_value y))))
      (add_reg_sext32 ty x y))
(rule 15 (lower (has_type (fits_in_64 ty) (iadd (sext32_value x) y)))
      (add_reg_sext32 ty y x))

;; Add a register and an immediate.
(rule 7 (lower (has_type (fits_in_64 ty) (iadd x (i16_from_value y))))
      (add_simm16 ty x y))
(rule 14 (lower (has_type (fits_in_64 ty) (iadd (i16_from_value x) y)))
      (add_simm16 ty y x))
(rule 6 (lower (has_type (fits_in_64 ty) (iadd x (i32_from_value y))))
      (add_simm32 ty x y))
(rule 13 (lower (has_type (fits_in_64 ty) (iadd (i32_from_value x) y)))
      (add_simm32 ty y x))

;; Add a register and memory (32/64-bit types).
(rule 5 (lower (has_type (fits_in_64 ty) (iadd x (sinkable_load_32_64 y))))
      (add_mem ty x (sink_load y)))
(rule 12 (lower (has_type (fits_in_64 ty) (iadd (sinkable_load_32_64 x) y)))
      (add_mem ty y (sink_load x)))

;; Add a register and memory (16-bit types).
(rule 4 (lower (has_type (fits_in_64 ty) (iadd x (sinkable_load_16 y))))
      (add_mem_sext16 ty x (sink_load y)))
(rule 11 (lower (has_type (fits_in_64 ty) (iadd (sinkable_load_16 x) y)))
      (add_mem_sext16 ty y (sink_load x)))

;; Add a register and sign-extended memory.
(rule 3 (lower (has_type (fits_in_64 ty) (iadd x (sinkable_sload16 y))))
      (add_mem_sext16 ty x (sink_sload16 y)))
(rule 10 (lower (has_type (fits_in_64 ty) (iadd (sinkable_sload16 x) y)))
      (add_mem_sext16 ty y (sink_sload16 x)))
(rule 2 (lower (has_type (fits_in_64 ty) (iadd x (sinkable_sload32 y))))
      (add_mem_sext32 ty x (sink_sload32 y)))
(rule 9 (lower (has_type (fits_in_64 ty) (iadd (sinkable_sload32 x) y)))
      (add_mem_sext32 ty y (sink_sload32 x)))

;; Add two vector registers.
(rule 1 (lower (has_type (vr128_ty ty) (iadd x y)))
      (vec_add ty x y))


;;;; Rules for `uadd_sat` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Add (saturate unsigned) two vector registers.
(rule (lower (has_type (ty_vec128 ty) (uadd_sat x y)))
      (let ((sum Reg (vec_add ty x y)))
        (vec_or ty sum (vec_cmphl ty x sum))))


;;;; Rules for `sadd_sat` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Add (saturate signed) two vector registers.  $I64X2 not supported.
(rule (lower (has_type (ty_vec128 ty) (sadd_sat x y)))
      (vec_pack_ssat (vec_widen_type ty)
                     (vec_add (vec_widen_type ty) (vec_unpacks_high ty x)
                                                  (vec_unpacks_high ty y))
                     (vec_add (vec_widen_type ty) (vec_unpacks_low ty x)
                                                  (vec_unpacks_low ty y))))


;;;; Rules for `iadd_pairwise` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Lane-wise integer pairwise addition for 8-/16/32-bit vector registers.
(rule (lower (has_type ty @ (multi_lane bits _) (iadd_pairwise x y)))
      (let ((size Reg (vec_imm_splat $I8X16 (u32_as_u64 bits))))
        (vec_pack_lane_order (vec_widen_type ty)
                             (vec_add ty x (vec_lshr_by_byte x size))
                             (vec_add ty y (vec_lshr_by_byte y size)))))

;; special case for the `i32x4.dot_i16x8_s` wasm instruction
(rule 1 (lower
        (has_type dst_ty (iadd_pairwise
                           (imul (swiden_low x @ (value_type src_ty)) (swiden_low y))
                           (imul (swiden_high x) (swiden_high y)))))
      (vec_add dst_ty (vec_smul_even src_ty x y)
                      (vec_smul_odd src_ty x y)))


;;;; Rules for `isub` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Sub two registers.
(rule 0 (lower (has_type (fits_in_64 ty) (isub x y)))
      (sub_reg ty x y))

;; Sub a register and a sign-extended register.
(rule 8 (lower (has_type (fits_in_64 ty) (isub x (sext32_value y))))
      (sub_reg_sext32 ty x y))

;; Sub a register and an immediate (using add of the negated value).
(rule 7 (lower (has_type (fits_in_64 ty) (isub x (i16_from_negated_value y))))
      (add_simm16 ty x y))
(rule 6 (lower (has_type (fits_in_64 ty) (isub x (i32_from_negated_value y))))
      (add_simm32 ty x y))

;; Sub a register and memory (32/64-bit types).
(rule 5 (lower (has_type (fits_in_64 ty) (isub x (sinkable_load_32_64 y))))
      (sub_mem ty x (sink_load y)))

;; Sub a register and memory (16-bit types).
(rule 4 (lower (has_type (fits_in_64 ty) (isub x (sinkable_load_16 y))))
      (sub_mem_sext16 ty x (sink_load y)))

;; Sub a register and sign-extended memory.
(rule 3 (lower (has_type (fits_in_64 ty) (isub x (sinkable_sload16 y))))
      (sub_mem_sext16 ty x (sink_sload16 y)))
(rule 2 (lower (has_type (fits_in_64 ty) (isub x (sinkable_sload32 y))))
      (sub_mem_sext32 ty x (sink_sload32 y)))

;; Sub two vector registers.
(rule 1 (lower (has_type (vr128_ty ty) (isub x y)))
      (vec_sub ty x y))


;;;; Rules for `usub_sat` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Add (saturate unsigned) two vector registers.
(rule (lower (has_type (ty_vec128 ty) (usub_sat x y)))
      (vec_and ty (vec_sub ty x y) (vec_cmphl ty x y)))


;;;; Rules for `ssub_sat` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Add (saturate signed) two vector registers.  $I64X2 not supported.
(rule (lower (has_type (ty_vec128 ty) (ssub_sat x y)))
      (vec_pack_ssat (vec_widen_type ty)
                     (vec_sub (vec_widen_type ty) (vec_unpacks_high ty x)
                                                  (vec_unpacks_high ty y))
                     (vec_sub (vec_widen_type ty) (vec_unpacks_low ty x)
                                                  (vec_unpacks_low ty y))))


;;;; Rules for `iabs` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Absolute value of a register.
;; For types smaller than 32-bit, the input value must be sign-extended.
(rule 2 (lower (has_type (fits_in_64 ty) (iabs x)))
      (abs_reg (ty_ext32 ty) (put_in_reg_sext32 x)))

;; Absolute value of a sign-extended register.
(rule 3 (lower (has_type (fits_in_64 ty) (iabs (sext32_value x))))
      (abs_reg_sext32 ty x))

;; Absolute value of a vector register.
(rule 1 (lower (has_type (ty_vec128 ty) (iabs x)))
      (vec_abs ty x))

;; Absolute value of a 128-bit integer.
(rule 0 (lower (has_type $I128 (iabs x)))
      (let ((zero Reg (vec_imm $I128 0))
            (pos Reg x)
            (neg Reg (vec_sub $I128 zero pos))
            (rep Reg (vec_replicate_lane $I64X2 pos 0))
            (mask Reg (vec_cmph $I64X2 zero rep)))
        (vec_select $I128 neg pos mask)))


;;;; Rules for `ineg` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Negate a register.
(rule 2 (lower (has_type (fits_in_64 ty) (ineg x)))
      (neg_reg ty x))

;; Negate a sign-extended register.
(rule 3 (lower (has_type (fits_in_64 ty) (ineg (sext32_value x))))
      (neg_reg_sext32 ty x))

;; Negate a vector register.
(rule 1 (lower (has_type (ty_vec128 ty) (ineg x)))
      (vec_neg ty x))

;; Negate a 128-bit integer.
(rule 0 (lower (has_type $I128 (ineg x)))
      (vec_sub $I128 (vec_imm $I128 0) x))


;;;; Rules for `umax` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Unsigned maximum of two scalar integers - expand to icmp + select.
(rule 2 (lower (has_type (fits_in_64 ty) (umax x y)))
      (let ((x_ext Reg (put_in_reg_zext32 x))
            (y_ext Reg (put_in_reg_zext32 y))
            (cond ProducesBool (bool (icmpu_reg (ty_ext32 ty) x_ext y_ext)
                                     (intcc_as_cond (IntCC.UnsignedLessThan)))))
        (select_bool_reg ty cond y_ext x_ext)))

;; Unsigned maximum of two 128-bit integers - expand to icmp + select.
(rule 1 (lower (has_type $I128 (umax x y)))
      (let ((x_reg Reg (put_in_reg x))
            (y_reg Reg (put_in_reg y))
            (cond ProducesBool (vec_int128_ucmphi y_reg x_reg)))
        (select_bool_reg $I128 cond y_reg x_reg)))

;; Unsigned maximum of two vector registers.
(rule 0 (lower (has_type (ty_vec128 ty) (umax x y)))
      (vec_umax ty x y))


;;;; Rules for `umin` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Unsigned minimum of two scalar integers - expand to icmp + select.
(rule 2 (lower (has_type (fits_in_64 ty) (umin x y)))
      (let ((x_ext Reg (put_in_reg_zext32 x))
            (y_ext Reg (put_in_reg_zext32 y))
            (cond ProducesBool (bool (icmpu_reg (ty_ext32 ty) x_ext y_ext)
                                     (intcc_as_cond (IntCC.UnsignedGreaterThan)))))
        (select_bool_reg ty cond y_ext x_ext)))

;; Unsigned maximum of two 128-bit integers - expand to icmp + select.
(rule 1 (lower (has_type $I128 (umin x y)))
      (let ((x_reg Reg (put_in_reg x))
            (y_reg Reg (put_in_reg y))
            (cond ProducesBool (vec_int128_ucmphi x_reg y_reg)))
        (select_bool_reg $I128 cond y_reg x_reg)))

;; Unsigned minimum of two vector registers.
(rule 0 (lower (has_type (ty_vec128 ty) (umin x y)))
      (vec_umin ty x y))


;;;; Rules for `smax` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Signed maximum of two scalar integers - expand to icmp + select.
(rule 2 (lower (has_type (fits_in_64 ty) (smax x y)))
      (let ((x_ext Reg (put_in_reg_sext32 x))
            (y_ext Reg (put_in_reg_sext32 y))
            (cond ProducesBool (bool (icmps_reg (ty_ext32 ty) x_ext y_ext)
                                     (intcc_as_cond (IntCC.SignedLessThan)))))
        (select_bool_reg ty cond y_ext x_ext)))

;; Signed maximum of two 128-bit integers - expand to icmp + select.
(rule 1 (lower (has_type $I128 (smax x y)))
      (let ((x_reg Reg (put_in_reg x))
            (y_reg Reg (put_in_reg y))
            (cond ProducesBool (vec_int128_scmphi y_reg x_reg)))
        (select_bool_reg $I128 cond y_reg x_reg)))

;; Signed maximum of two vector registers.
(rule (lower (has_type (ty_vec128 ty) (smax x y)))
      (vec_smax ty x y))


;;;; Rules for `smin` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Signed minimum of two scalar integers - expand to icmp + select.
(rule 2 (lower (has_type (fits_in_64 ty) (smin x y)))
      (let ((x_ext Reg (put_in_reg_sext32 x))
            (y_ext Reg (put_in_reg_sext32 y))
            (cond ProducesBool (bool (icmps_reg (ty_ext32 ty) x_ext y_ext)
                                     (intcc_as_cond (IntCC.SignedGreaterThan)))))
        (select_bool_reg ty cond y_ext x_ext)))

;; Signed maximum of two 128-bit integers - expand to icmp + select.
(rule 1 (lower (has_type $I128 (smin x y)))
      (let ((x_reg Reg (put_in_reg x))
            (y_reg Reg (put_in_reg y))
            (cond ProducesBool (vec_int128_scmphi x_reg y_reg)))
        (select_bool_reg $I128 cond y_reg x_reg)))

;; Signed minimum of two vector registers.
(rule (lower (has_type (ty_vec128 ty) (smin x y)))
      (vec_smin ty x y))


;;;; Rules for `avg_round` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Unsigned average of two vector registers.
(rule (lower (has_type (ty_vec128 ty) (avg_round x y)))
      (vec_uavg ty x y))


;;;; Rules for `imul` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Multiply two registers.
(rule 0 (lower (has_type (fits_in_64 ty) (imul x y)))
      (mul_reg ty x y))

;; Multiply a register and a sign-extended register.
(rule 8 (lower (has_type (fits_in_64 ty) (imul x (sext32_value y))))
      (mul_reg_sext32 ty x y))
(rule 15 (lower (has_type (fits_in_64 ty) (imul (sext32_value x) y)))
      (mul_reg_sext32 ty y x))

;; Multiply a register and an immediate.
(rule 7 (lower (has_type (fits_in_64 ty) (imul x (i16_from_value y))))
      (mul_simm16 ty x y))
(rule 14 (lower (has_type (fits_in_64 ty) (imul (i16_from_value x) y)))
      (mul_simm16 ty y x))
(rule 6 (lower (has_type (fits_in_64 ty) (imul x (i32_from_value y))))
      (mul_simm32 ty x y))
(rule 13 (lower (has_type (fits_in_64 ty) (imul (i32_from_value x) y)))
      (mul_simm32 ty y x))

;; Multiply a register and memory (32/64-bit types).
(rule 5 (lower (has_type (fits_in_64 ty) (imul x (sinkable_load_32_64 y))))
      (mul_mem ty x (sink_load y)))
(rule 12 (lower (has_type (fits_in_64 ty) (imul (sinkable_load_32_64 x) y)))
      (mul_mem ty y (sink_load x)))

;; Multiply a register and memory (16-bit types).
(rule 4 (lower (has_type (fits_in_64 ty) (imul x (sinkable_load_16 y))))
      (mul_mem_sext16 ty x (sink_load y)))
(rule 11 (lower (has_type (fits_in_64 ty) (imul (sinkable_load_16 x) y)))
      (mul_mem_sext16 ty y (sink_load x)))

;; Multiply a register and sign-extended memory.
(rule 3 (lower (has_type (fits_in_64 ty) (imul x (sinkable_sload16 y))))
      (mul_mem_sext16 ty x (sink_sload16 y)))
(rule 10 (lower (has_type (fits_in_64 ty) (imul (sinkable_sload16 x) y)))
      (mul_mem_sext16 ty y (sink_sload16 x)))
(rule 2 (lower (has_type (fits_in_64 ty) (imul x (sinkable_sload32 y))))
      (mul_mem_sext32 ty x (sink_sload32 y)))
(rule 9 (lower (has_type (fits_in_64 ty) (imul (sinkable_sload32 x) y)))
      (mul_mem_sext32 ty y (sink_sload32 x)))

;; Multiply two vector registers, using a helper.
(decl vec_mul_impl (Type Reg Reg) Reg)
(rule 1 (lower (has_type (vr128_ty ty) (imul x y)))
      (vec_mul_impl ty x y))

;; Multiply two vector registers - byte, halfword, and word.
(rule (vec_mul_impl $I8X16 x y) (vec_mul $I8X16 x y))
(rule (vec_mul_impl $I16X8 x y) (vec_mul $I16X8 x y))
(rule (vec_mul_impl $I32X4 x y) (vec_mul $I32X4 x y))

;; Multiply two vector registers - doubleword.  Has to be scalarized.
(rule (vec_mul_impl $I64X2 x y)
      (mov_to_vec128 $I64X2
                     (mul_reg $I64 (vec_extract_lane $I64X2 x 0 (zero_reg))
                                   (vec_extract_lane $I64X2 y 0 (zero_reg)))
                     (mul_reg $I64 (vec_extract_lane $I64X2 x 1 (zero_reg))
                                   (vec_extract_lane $I64X2 y 1 (zero_reg)))))

;; Multiply two vector registers - quadword.
(rule (vec_mul_impl $I128 x y)
      (let ((x_hi Reg (vec_extract_lane $I64X2 x 0 (zero_reg)))
            (x_lo Reg (vec_extract_lane $I64X2 x 1 (zero_reg)))
            (y_hi Reg (vec_extract_lane $I64X2 y 0 (zero_reg)))
            (y_lo Reg (vec_extract_lane $I64X2 y 1 (zero_reg)))
            (lo_pair RegPair (umul_wide x_lo y_lo))
            (res_lo Reg (regpair_lo lo_pair))
            (res_hi_1 Reg (regpair_hi lo_pair))
            (res_hi_2 Reg (mul_reg $I64 x_lo y_hi))
            (res_hi_3 Reg (mul_reg $I64 x_hi y_lo))
            (res_hi Reg (add_reg $I64 res_hi_3 (add_reg $I64 res_hi_2 res_hi_1))))
        (mov_to_vec128 $I64X2 res_hi res_lo)))

;; Special-case the lowering of a 128-bit multiply where the operands are sign
;; or zero extended. This maps directly to `umul_wide` and `smul_wide`.
(rule 16 (lower (has_type $I128 (imul (uextend x) (uextend y))))
  (let ((pair RegPair (umul_wide (put_in_reg_zext64 x) (put_in_reg_zext64 y))))
    (mov_to_vec128 $I64X2 (regpair_hi pair) (regpair_lo pair))))

(rule 16 (lower (has_type $I128 (imul (sextend x) (sextend y))))
  (let ((pair RegPair (smul_wide (put_in_reg_sext64 x) (put_in_reg_sext64 y))))
    (mov_to_vec128 $I64X2 (regpair_hi pair) (regpair_lo pair))))

;;;; Rules for `umulhi` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Multiply high part unsigned, 8-bit or 16-bit types.  (Uses 32-bit multiply.)
(rule -1 (lower (has_type (ty_8_or_16 ty) (umulhi x y)))
      (let ((ext_reg_x Reg (put_in_reg_zext32 x))
            (ext_reg_y Reg (put_in_reg_zext32 y))
            (ext_mul Reg (mul_reg $I32 ext_reg_x ext_reg_y)))
        (lshr_imm $I32 ext_mul (ty_bits ty))))

;; Multiply high part unsigned, 32-bit types.  (Uses 64-bit multiply.)
(rule (lower (has_type $I32 (umulhi x y)))
      (let ((ext_reg_x Reg (put_in_reg_zext64 x))
            (ext_reg_y Reg (put_in_reg_zext64 y))
            (ext_mul Reg (mul_reg $I64 ext_reg_x ext_reg_y)))
        (lshr_imm $I64 ext_mul 32)))

;; Multiply high part unsigned, 64-bit types.  (Uses umul_wide.)
(rule (lower (has_type $I64 (umulhi x y)))
      (let ((pair RegPair (umul_wide x y)))
        (regpair_hi pair)))

;; Multiply high part unsigned, vector types with 8-, 16-, or 32-bit elements.
(rule (lower (has_type $I8X16 (umulhi x y))) (vec_umulhi $I8X16 x y))
(rule (lower (has_type $I16X8 (umulhi x y))) (vec_umulhi $I16X8 x y))
(rule (lower (has_type $I32X4 (umulhi x y))) (vec_umulhi $I32X4 x y))

;; Multiply high part unsigned, vector types with 64-bit elements.
;; Has to be scalarized.
(rule (lower (has_type $I64X2 (umulhi x y)))
      (let ((pair_0 RegPair (umul_wide (vec_extract_lane $I64X2 x 0 (zero_reg))
                                       (vec_extract_lane $I64X2 y 0 (zero_reg))))
            (res_0 Reg (regpair_hi pair_0))
            (pair_1 RegPair (umul_wide (vec_extract_lane $I64X2 x 1 (zero_reg))
                                       (vec_extract_lane $I64X2 y 1 (zero_reg))))
            (res_1 Reg (regpair_hi pair_1)))
        (mov_to_vec128 $I64X2 res_0 res_1)))


;;;; Rules for `smulhi` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Multiply high part signed, 8-bit or 16-bit types.  (Uses 32-bit multiply.)
(rule -1 (lower (has_type (ty_8_or_16 ty) (smulhi x y)))
      (let ((ext_reg_x Reg (put_in_reg_sext32 x))
            (ext_reg_y Reg (put_in_reg_sext32 y))
            (ext_mul Reg (mul_reg $I32 ext_reg_x ext_reg_y)))
        (ashr_imm $I32 ext_mul (ty_bits ty))))

;; Multiply high part signed, 32-bit types.  (Uses 64-bit multiply.)
(rule (lower (has_type $I32 (smulhi x y)))
      (let ((ext_reg_x Reg (put_in_reg_sext64 x))
            (ext_reg_y Reg (put_in_reg_sext64 y))
            (ext_mul Reg (mul_reg $I64 ext_reg_x ext_reg_y)))
        (ashr_imm $I64 ext_mul 32)))

;; Multiply high part signed, 64-bit types.  (Uses smul_wide.)
(rule (lower (has_type $I64 (smulhi x y)))
      (let ((pair RegPair (smul_wide x y)))
        (regpair_hi pair)))

;; Multiply high part signed, vector types with 8-, 16-, or 32-bit elements.
(rule (lower (has_type $I8X16 (smulhi x y))) (vec_smulhi $I8X16 x y))
(rule (lower (has_type $I16X8 (smulhi x y))) (vec_smulhi $I16X8 x y))
(rule (lower (has_type $I32X4 (smulhi x y))) (vec_smulhi $I32X4 x y))

;; Multiply high part unsigned, vector types with 64-bit elements.
;; Has to be scalarized.
(rule (lower (has_type $I64X2 (smulhi x y)))
      (let ((pair_0 RegPair (smul_wide (vec_extract_lane $I64X2 x 0 (zero_reg))
                                       (vec_extract_lane $I64X2 y 0 (zero_reg))))
            (res_0 Reg (copy_reg $I64 (regpair_hi pair_0)))
            (pair_1 RegPair (smul_wide (vec_extract_lane $I64X2 x 1 (zero_reg))
                                       (vec_extract_lane $I64X2 y 1 (zero_reg))))
            (res_1 Reg (regpair_hi pair_1)))
        (mov_to_vec128 $I64X2 res_0 res_1)))


;;;; Rules for `sqmul_round_sat` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Fixed-point multiplication of two vector registers.
(rule (lower (has_type (ty_vec128 ty) (sqmul_round_sat x y)))
      (vec_pack_ssat (vec_widen_type ty)
                     (sqmul_impl (vec_widen_type ty)
                                 (vec_unpacks_high ty x)
                                 (vec_unpacks_high ty y))
                     (sqmul_impl (vec_widen_type ty)
                                 (vec_unpacks_low ty x)
                                 (vec_unpacks_low ty y))))

;; Helper to perform the rounded multiply in the wider type.
(decl sqmul_impl (Type Reg Reg) Reg)
(rule (sqmul_impl $I32X4 x y)
      (vec_ashr_imm $I32X4 (vec_add $I32X4 (vec_mul_impl $I32X4 x y)
                                           (vec_imm_bit_mask $I32X4 17 17))
                           15))
(rule (sqmul_impl $I64X2 x y)
      (vec_ashr_imm $I64X2 (vec_add $I64X2 (vec_mul_impl $I64X2 x y)
                                           (vec_imm_bit_mask $I64X2 33 33))
                           31))


;;;; Rules for `udiv` and `urem` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Divide two registers.  The architecture provides combined udiv / urem
;; instructions with the following combination of data types:
;;
;;  - 64-bit dividend (split across a 2x32-bit register pair),
;;    32-bit divisor (in a single input register)
;;    32-bit quotient & remainder (in a 2x32-bit register pair)
;;
;;  - 128-bit dividend (split across a 2x64-bit register pair),
;;    64-bit divisor (in a single input register)
;;    64-bit quotient & remainder (in a 2x64-bit register pair)
;;
;; We use the first variant for 32-bit and smaller input types,
;; and the second variant for 64-bit input types.

;; Implement `udiv`.
(rule (lower (has_type (fits_in_64 ty) (udiv x y)))
      (let (
            ;; Look at the divisor to determine whether we need to generate
            ;; an explicit division-by zero check.
            ;; Load up the dividend, by loading the input (possibly zero-
            ;; extended) input into the low half of the register pair,
            ;; and setting the high half to zero.
            (ext_x RegPair (regpair (imm (ty_ext32 ty) 0)
                                    (put_in_reg_zext32 x)))
            ;; Load up the divisor, zero-extended if necessary.
            (ext_y Reg (put_in_reg_zext32 y))
            (ext_ty Type (ty_ext32 ty))
            ;; Emit the actual divide instruction.
            (pair RegPair (udivmod ext_ty ext_x ext_y)))
        ;; The quotient can be found in the low half of the result.
        (regpair_lo pair)))

;; Implement `urem`.  Same as `udiv`, but finds the remainder in
;; the high half of the result register pair instead.
(rule (lower (has_type (fits_in_64 ty) (urem x y)))
      (let ((ext_x RegPair (regpair (imm (ty_ext32 ty) 0)
                                    (put_in_reg_zext32 x)))
            (ext_y Reg (put_in_reg_zext32 y))
            (ext_ty Type (ty_ext32 ty))
            (pair RegPair (udivmod ext_ty ext_x ext_y)))
        (regpair_hi pair)))


;;;; Rules for `sdiv` and `srem` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Divide two registers.  The architecture provides combined sdiv / srem
;; instructions with the following combination of data types:
;;
;;  - 64-bit dividend (in the low half of a 2x64-bit register pair),
;;    32-bit divisor (in a single input register)
;;    64-bit quotient & remainder (in a 2x64-bit register pair)
;;
;;  - 64-bit dividend (in the low half of a 2x64-bit register pair),
;;    64-bit divisor (in a single input register)
;;    64-bit quotient & remainder (in a 2x64-bit register pair)
;;
;; We use the first variant for 32-bit and smaller input types,
;; and the second variant for 64-bit input types.

;; Implement `sdiv`.
(rule (lower (has_type (fits_in_64 ty) (sdiv x y)))
      (let (
            ;; Look at the divisor to determine whether we need to generate
            ;; explicit division-by-zero and/or integer-overflow checks.
            (OFcheck bool (div_overflow_check_needed y))
            ;; Load up the dividend (sign-extended to 64-bit)
            (ext_x Reg (put_in_reg_sext64 x))
            ;; Load up the divisor (sign-extended if necessary).
            (ext_y Reg (put_in_reg_sext32 y))
            (ext_ty Type (ty_ext32 ty))
            ;; Perform integer-overflow check if necessary.
            (_ Reg (maybe_trap_if_sdiv_overflow OFcheck ext_ty ty ext_x ext_y))
            ;; Emit the actual divide instruction.
            (pair RegPair (sdivmod ext_ty ext_x ext_y)))
        ;; The quotient can be found in the low half of the result.
        (regpair_lo pair)))

;; Implement `srem`.  Same as `sdiv`, but finds the remainder in
;; the high half of the result register pair instead.  Also, handle
;; the integer overflow case differently, see below.
(rule (lower (has_type (fits_in_64 ty) (srem x y)))
      (let ((OFcheck bool (div_overflow_check_needed y))
            (ext_x Reg (put_in_reg_sext64 x))
            (ext_y Reg (put_in_reg_sext32 y))
            (ext_ty Type (ty_ext32 ty))
            (checked_x Reg (maybe_avoid_srem_overflow OFcheck ext_ty ext_x ext_y))
            (pair RegPair (sdivmod ext_ty checked_x ext_y)))
        (regpair_hi pair)))

;; Determine whether we need to perform an integer-overflow check.
;;
;; We never rely on the divide instruction itself to trap; while that trap
;; would indeed happen, we have no way of signalling two different trap
;; conditions from the same instruction.  By explicitly checking for the
;; integer-overflow case ahead of time, any hardware trap in the divide
;; instruction is guaranteed to indicate division-by-zero.
;;
;; In addition, for types smaller than 64 bits we would have to perform
;; the check explicitly anyway, since the instruction provides a 64-bit
;; quotient and only traps if *that* overflows.
;;
;; However, the only case where integer overflow can occur is if the
;; minimum (signed) integer value is divided by -1, so if the divisor
;; is any immediate different from -1, the check can be omitted.
(decl div_overflow_check_needed (Value) bool)
(rule 1 (div_overflow_check_needed (i64_from_value x))
      (if (i64_not_neg1 x))
      false)
(rule (div_overflow_check_needed _) true)

;; Perform the integer-overflow check if necessary.   This implements:
;;
;;    if divisor == INT_MIN && dividend == -1 { trap }
;;
;; but to avoid introducing control flow, it is actually done as:
;;
;;    if ((divisor ^ INT_MAX) & dividend) == -1 { trap }
;;
;; instead, using a single conditional trap instruction.
(decl maybe_trap_if_sdiv_overflow (bool Type Type Reg Reg) Reg)
(rule (maybe_trap_if_sdiv_overflow false ext_ty _ _ _) (invalid_reg))
(rule (maybe_trap_if_sdiv_overflow true ext_ty ty x y)
      (let ((int_max Reg (imm ext_ty (int_max ty)))
            (reg Reg (and_reg ext_ty (xor_reg ext_ty int_max x) y)))
        (icmps_simm16_and_trap ext_ty reg -1
                               (intcc_as_cond (IntCC.Equal))
                               (trap_code_integer_overflow))))
(decl int_max (Type) u64)
(rule (int_max $I8) 0x7f)
(rule (int_max $I16) 0x7fff)
(rule (int_max $I32) 0x7fffffff)
(rule (int_max $I64) 0x7fffffffffffffff)

;; When performing `srem`, we do not want to trap in the
;; integer-overflow scenario, because it is only the quotient
;; that overflows, not the remainder.
;;
;; For types smaller than 64 bits, we can simply let the
;; instruction execute, since (as above) it will never trap.
;;
;; For 64-bit inputs, we check whether the divisor is -1, and
;; if so simply replace the dividend by zero, which will give
;; the correct result, since any value modulo -1 is zero.
;;
;; (We could in fact avoid executing the divide instruction
;; at all in this case, but that would require introducing
;; control flow.)
(decl maybe_avoid_srem_overflow (bool Type Reg Reg) Reg)
(rule (maybe_avoid_srem_overflow false _ x _) x)
(rule (maybe_avoid_srem_overflow true $I32 x _) x)
(rule (maybe_avoid_srem_overflow true $I64 x y)
      (with_flags_reg (icmps_simm16 $I64 y -1)
                      (cmov_imm $I64 (intcc_as_cond (IntCC.Equal)) 0 x)))


;;;; Rules for `ishl` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Shift left, shift amount in register.
(rule 0 (lower (has_type (fits_in_64 ty) (ishl x y)))
      (let ((masked_amt Reg (mask_amt_reg ty (amt_reg y))))
        (lshl_reg ty x masked_amt)))

;; Shift left, immediate shift amount.
(rule 1 (lower (has_type (fits_in_64 ty) (ishl x (i64_from_value y))))
      (let ((masked_amt u8 (mask_amt_imm ty y)))
        (lshl_imm ty x masked_amt)))

;; Vector shift left, shift amount in register.
(rule 2 (lower (has_type (ty_vec128 ty) (ishl x y)))
      (vec_lshl_reg ty x (amt_reg y)))

;; Vector shift left, immediate shift amount.
(rule 3 (lower (has_type (ty_vec128 ty) (ishl x (i64_from_value y))))
      (let ((masked_amt u8 (mask_amt_imm ty y)))
        (vec_lshl_imm ty x masked_amt)))

;; 128-bit vector shift left.
(rule 4 (lower (has_type $I128 (ishl x y)))
      (let ((amt Reg (amt_vr y)))
        (vec_lshl_by_bit (vec_lshl_by_byte x amt) amt)))


;;;; Rules for `ushr` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Shift right logical, shift amount in register.
;; For types smaller than 32-bit, the input value must be zero-extended.
(rule 0 (lower (has_type (fits_in_64 ty) (ushr x y)))
      (let ((ext_reg Reg (put_in_reg_zext32 x))
            (masked_amt Reg (mask_amt_reg ty (amt_reg y))))
        (lshr_reg (ty_ext32 ty) ext_reg masked_amt)))

;; Shift right logical, immediate shift amount.
;; For types smaller than 32-bit, the input value must be zero-extended.
(rule 1 (lower (has_type (fits_in_64 ty) (ushr x (i64_from_value y))))
      (let ((ext_reg Reg (put_in_reg_zext32 x))
            (masked_amt u8 (mask_amt_imm ty y)))
        (lshr_imm (ty_ext32 ty) ext_reg masked_amt)))

;; Vector shift right logical, shift amount in register.
(rule 2 (lower (has_type (ty_vec128 ty) (ushr x y)))
      (vec_lshr_reg ty x (amt_reg y)))

;; Vector shift right logical, immediate shift amount.
(rule 3 (lower (has_type (ty_vec128 ty) (ushr x (i64_from_value y))))
      (let ((masked_amt u8 (mask_amt_imm ty y)))
        (vec_lshr_imm ty x masked_amt)))

;; 128-bit vector shift right logical.
(rule 4 (lower (has_type $I128 (ushr x y)))
      (let ((amt Reg (amt_vr y)))
        (vec_lshr_by_bit (vec_lshr_by_byte x amt) amt)))


;;;; Rules for `sshr` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Shift right arithmetic, shift amount in register.
;; For types smaller than 32-bit, the input value must be sign-extended.
(rule 0 (lower (has_type (fits_in_64 ty) (sshr x y)))
      (let ((ext_reg Reg (put_in_reg_sext32 x))
            (masked_amt Reg (mask_amt_reg ty (amt_reg y))))
        (ashr_reg (ty_ext32 ty) ext_reg masked_amt)))

;; Shift right arithmetic, immediate shift amount.
;; For types smaller than 32-bit, the input value must be sign-extended.
(rule 1 (lower (has_type (fits_in_64 ty) (sshr x (i64_from_value y))))
      (let ((ext_reg Reg (put_in_reg_sext32 x))
            (masked_amt u8 (mask_amt_imm ty y)))
        (ashr_imm (ty_ext32 ty) ext_reg masked_amt)))

;; Vector shift right arithmetic, shift amount in register.
(rule 2 (lower (has_type (ty_vec128 ty) (sshr x y)))
      (vec_ashr_reg ty x (amt_reg y)))

;; Vector shift right arithmetic, immediate shift amount.
(rule 3 (lower (has_type (ty_vec128 ty) (sshr x (i64_from_value y))))
      (let ((masked_amt u8 (mask_amt_imm ty y)))
        (vec_ashr_imm ty x masked_amt)))

;; 128-bit vector shift right arithmetic.
(rule 4 (lower (has_type $I128 (sshr x y)))
      (let ((amt Reg (amt_vr y)))
        (vec_ashr_by_bit (vec_ashr_by_byte x amt) amt)))


;;;; Rules for `rotl` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Rotate left, shift amount in register.  32-bit or 64-bit types.
(rule 0 (lower (has_type (ty_32_or_64 ty) (rotl x y)))
      (rot_reg ty x (amt_reg y)))

;; Rotate left arithmetic, immediate shift amount.  32-bit or 64-bit types.
(rule 1 (lower (has_type (ty_32_or_64 ty) (rotl x (i64_from_value y))))
      (let ((masked_amt u8 (mask_amt_imm ty y)))
        (rot_imm ty x masked_amt)))

;; Rotate left, shift amount in register.  8-bit or 16-bit types.
;; Implemented via a pair of 32-bit shifts on the zero-extended input.
(rule 2 (lower (has_type (ty_8_or_16 ty) (rotl x y)))
      (let ((ext_reg Reg (put_in_reg_zext32 x))
            (ext_ty Type (ty_ext32 ty))
            (pos_amt Reg (amt_reg y))
            (neg_amt Reg (neg_reg $I32 pos_amt))
            (masked_pos_amt Reg (mask_amt_reg ty pos_amt))
            (masked_neg_amt Reg (mask_amt_reg ty neg_amt)))
        (or_reg ty (lshl_reg ext_ty ext_reg masked_pos_amt)
                (lshr_reg ext_ty ext_reg masked_neg_amt))))

;; Rotate left, immediate shift amount.  8-bit or 16-bit types.
;; Implemented via a pair of 32-bit shifts on the zero-extended input.
(rule 3 (lower (has_type (ty_8_or_16 ty) (rotl x (and (i64_from_value pos_amt)
                                                    (i64_from_negated_value neg_amt)))))
      (let ((ext_reg Reg (put_in_reg_zext32 x))
            (ext_ty Type (ty_ext32 ty))
            (masked_pos_amt u8 (mask_amt_imm ty pos_amt))
            (masked_neg_amt u8 (mask_amt_imm ty neg_amt)))
        (or_reg ty (lshl_imm ext_ty ext_reg masked_pos_amt)
                (lshr_imm ext_ty ext_reg masked_neg_amt))))

;; Vector rotate left, shift amount in register.
(rule 4 (lower (has_type (ty_vec128 ty) (rotl x y)))
      (vec_rot_reg ty x (amt_reg y)))

;; Vector rotate left, immediate shift amount.
(rule 5 (lower (has_type (ty_vec128 ty) (rotl x (i64_from_value y))))
      (let ((masked_amt u8 (mask_amt_imm ty y)))
        (vec_rot_imm ty x masked_amt)))

;; 128-bit full vector rotate left.
;; Implemented via a pair of 128-bit full vector shifts.
(rule 6 (lower (has_type $I128 (rotl x y)))
      (let ((x_reg Reg x)
            (pos_amt Reg (amt_vr y))
            (neg_amt Reg (vec_neg $I8X16 pos_amt)))
        (vec_or $I128
          (vec_lshl_by_bit (vec_lshl_by_byte x_reg pos_amt) pos_amt)
          (vec_lshr_by_bit (vec_lshr_by_byte x_reg neg_amt) neg_amt))))


;;;; Rules for `rotr` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Rotate right, shift amount in register.  32-bit or 64-bit types.
;; Implemented as rotate left with negated rotate amount.
(rule 0 (lower (has_type (ty_32_or_64 ty) (rotr x y)))
      (let ((negated_amt Reg (neg_reg $I32 (amt_reg y))))
        (rot_reg ty x negated_amt)))

;; Rotate right arithmetic, immediate shift amount.  32-bit or 64-bit types.
;; Implemented as rotate left with negated rotate amount.
(rule 1 (lower (has_type (ty_32_or_64 ty) (rotr x (i64_from_negated_value y))))
      (let ((negated_amt u8 (mask_amt_imm ty y)))
        (rot_imm ty x negated_amt)))

;; Rotate right, shift amount in register.  8-bit or 16-bit types.
;; Implemented as rotate left with negated rotate amount.
(rule 2 (lower (has_type (ty_8_or_16 ty) (rotr x y)))
      (let ((ext_reg Reg (put_in_reg_zext32 x))
            (ext_ty Type (ty_ext32 ty))
            (pos_amt Reg (amt_reg y))
            (neg_amt Reg (neg_reg $I32 pos_amt))
            (masked_pos_amt Reg (mask_amt_reg ty pos_amt))
            (masked_neg_amt Reg (mask_amt_reg ty neg_amt)))
        (or_reg ty (lshl_reg ext_ty ext_reg masked_neg_amt)
                (lshr_reg ext_ty ext_reg masked_pos_amt))))

;; Rotate right, immediate shift amount.  8-bit or 16-bit types.
;; Implemented as rotate left with negated rotate amount.
(rule 3 (lower (has_type (ty_8_or_16 ty) (rotr x (and (i64_from_value pos_amt)
                                                    (i64_from_negated_value neg_amt)))))
      (let ((ext_reg Reg (put_in_reg_zext32 x))
            (ext_ty Type (ty_ext32 ty))
            (masked_pos_amt u8 (mask_amt_imm ty pos_amt))
            (masked_neg_amt u8 (mask_amt_imm ty neg_amt)))
        (or_reg ty (lshl_imm ext_ty ext_reg masked_neg_amt)
                (lshr_imm ext_ty ext_reg masked_pos_amt))))

;; Vector rotate right, shift amount in register.
;; Implemented as rotate left with negated rotate amount.
(rule 4 (lower (has_type (ty_vec128 ty) (rotr x y)))
      (let ((negated_amt Reg (neg_reg $I32 (amt_reg y))))
        (vec_rot_reg ty x negated_amt)))

;; Vector rotate right, immediate shift amount.
;; Implemented as rotate left with negated rotate amount.
(rule 5 (lower (has_type (ty_vec128 ty) (rotr x (i64_from_negated_value y))))
      (let ((negated_amt u8 (mask_amt_imm ty y)))
        (vec_rot_imm ty x negated_amt)))

;; 128-bit full vector rotate right.
;; Implemented via a pair of 128-bit full vector shifts.
(rule 6 (lower (has_type $I128 (rotr x y)))
      (let ((x_reg Reg x)
            (pos_amt Reg (amt_vr y))
            (neg_amt Reg (vec_neg $I8X16 pos_amt)))
        (vec_or $I128
          (vec_lshl_by_bit (vec_lshl_by_byte x_reg neg_amt) neg_amt)
          (vec_lshr_by_bit (vec_lshr_by_byte x_reg pos_amt) pos_amt))))


;;;; Rules for `ireduce` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Up to 64-bit source type: Always a no-op.
(rule 1 (lower (ireduce x @ (value_type (fits_in_64 _ty))))
      x)

;; 128-bit source type: Extract the low half.
(rule (lower (ireduce x @ (value_type (vr128_ty _ty))))
      (vec_extract_lane $I64X2 x 1 (zero_reg)))


;;;; Rules for `uextend` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; 16- or 32-bit target types.
(rule 1 (lower (has_type (gpr32_ty _ty) (uextend x)))
      (put_in_reg_zext32 x))

;; 64-bit target types.
(rule 2 (lower (has_type (gpr64_ty _ty) (uextend x)))
      (put_in_reg_zext64 x))

;; 128-bit target types.
(rule (lower (has_type $I128 (uextend x @ (value_type $I8))))
      (vec_insert_lane $I8X16 (vec_imm $I128 0) x 15 (zero_reg)))
(rule (lower (has_type $I128 (uextend x @ (value_type $I16))))
      (vec_insert_lane $I16X8 (vec_imm $I128 0) x 7 (zero_reg)))
(rule (lower (has_type $I128 (uextend x @ (value_type $I32))))
      (vec_insert_lane $I32X4 (vec_imm $I128 0) x 3 (zero_reg)))
(rule (lower (has_type $I128 (uextend x @ (value_type $I64))))
      (vec_insert_lane $I64X2 (vec_imm $I128 0) x 1 (zero_reg)))


;;;; Rules for `sextend` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; 16- or 32-bit target types.
(rule 1 (lower (has_type (gpr32_ty _ty) (sextend x)))
      (put_in_reg_sext32 x))

;; 64-bit target types.
(rule 2 (lower (has_type (gpr64_ty _ty) (sextend x)))
      (put_in_reg_sext64 x))

;; 128-bit target types.
(rule (lower (has_type $I128 (sextend x)))
      (let ((x_ext Reg (put_in_reg_sext64 x)))
        (mov_to_vec128 $I128 (ashr_imm $I64 x_ext 63) x_ext)))


;;;; Rules for `snarrow` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(rule (lower (snarrow x @ (value_type (ty_vec128 ty)) y))
      (vec_pack_ssat_lane_order ty x y))


;;;; Rules for `uunarrow` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(rule (lower (uunarrow x @ (value_type (ty_vec128 ty)) y))
      (vec_pack_usat_lane_order ty x y))


;;;; Rules for `unarrow` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(rule (lower (unarrow x @ (value_type (ty_vec128 ty)) y))
      (let ((zero Reg (vec_imm ty 0)))
        (vec_pack_usat_lane_order ty (vec_smax ty x zero) (vec_smax ty y zero))))


;;;; Rules for `swiden_low` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(rule (lower (swiden_low x @ (value_type (ty_vec128 ty))))
      (vec_unpacks_low_lane_order ty x))


;;;; Rules for `swiden_high` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(rule (lower (swiden_high x @ (value_type (ty_vec128 ty))))
      (vec_unpacks_high_lane_order ty x))


;;;; Rules for `uwiden_low` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(rule (lower (uwiden_low x @ (value_type (ty_vec128 ty))))
      (vec_unpacku_low_lane_order ty x))


;;;; Rules for `uwiden_high` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(rule (lower (uwiden_high x @ (value_type (ty_vec128 ty))))
      (vec_unpacku_high_lane_order ty x))


;;;; Rules for `bnot` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; z15 version using a single instruction (NOR).
(rule 2 (lower (has_type (and (mie2_enabled) (fits_in_64 ty)) (bnot x)))
      (let ((rx Reg x))
        (not_or_reg ty rx rx)))

;; z14 version using XOR with -1.
(rule 1 (lower (has_type (and (mie2_disabled) (fits_in_64 ty)) (bnot x)))
      (not_reg ty x))

;; Vector version using vector NOR.
(rule (lower (has_type (vr128_ty ty) (bnot x)))
      (vec_not ty x))

;; With z15 (bnot (bxor ...)) can be a single instruction, similar to the
;; (bxor _ (bnot _)) lowering.
(rule 3 (lower (has_type (and (mie2_enabled) (fits_in_64 ty)) (bnot (bxor x y))))
      (not_xor_reg ty x y))

;; Combine a not/xor operation of vector types into one.
(rule 4 (lower (has_type (vr128_ty ty) (bnot (bxor x y))))
      (vec_not_xor ty x y))


;;;; Rules for `band` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; And two registers.
(rule -1 (lower (has_type (fits_in_64 ty) (band x y)))
      (and_reg ty x y))

;; And a register and an immediate.
(rule 5 (lower (has_type (fits_in_64 ty) (band x (uimm16shifted_from_inverted_value y))))
      (and_uimm16shifted ty x y))
(rule 6 (lower (has_type (fits_in_64 ty) (band (uimm16shifted_from_inverted_value x) y)))
      (and_uimm16shifted ty y x))
(rule 3 (lower (has_type (fits_in_64 ty) (band x (uimm32shifted_from_inverted_value y))))
      (and_uimm32shifted ty x y))
(rule 4 (lower (has_type (fits_in_64 ty) (band (uimm32shifted_from_inverted_value x) y)))
      (and_uimm32shifted ty y x))

;; And a register and memory (32/64-bit types).
(rule 1 (lower (has_type (fits_in_64 ty) (band x (sinkable_load_32_64 y))))
      (and_mem ty x (sink_load y)))
(rule 2 (lower (has_type (fits_in_64 ty) (band (sinkable_load_32_64 x) y)))
      (and_mem ty y (sink_load x)))

;; And two vector registers.
(rule 0 (lower (has_type (vr128_ty ty) (band x y)))
      (vec_and ty x y))

;; Specialized lowerings for `(band x (bnot y))` which is additionally produced
;; by Cranelift's `band_not` instruction that is legalized into the simpler
;; forms early on.

;; z15 version using a single instruction.
(rule 7 (lower (has_type (and (mie2_enabled) (fits_in_64 ty)) (band x (bnot y))))
      (and_not_reg ty x y))
(rule 8 (lower (has_type (and (mie2_enabled) (fits_in_64 ty)) (band (bnot y) x)))
      (and_not_reg ty x y))

;; And-not two vector registers.
(rule 9 (lower (has_type (vr128_ty ty) (band x (bnot y))))
      (vec_and_not ty x y))
(rule 10 (lower (has_type (vr128_ty ty) (band (bnot y) x)))
      (vec_and_not ty x y))

;;;; Rules for `bor` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Or two registers.
(rule -1 (lower (has_type (fits_in_64 ty) (bor x y)))
      (or_reg ty x y))

;; Or a register and an immediate.
(rule 5 (lower (has_type (fits_in_64 ty) (bor x (uimm16shifted_from_value y))))
      (or_uimm16shifted ty x y))
(rule 6 (lower (has_type (fits_in_64 ty) (bor (uimm16shifted_from_value x) y)))
      (or_uimm16shifted ty y x))
(rule 3 (lower (has_type (fits_in_64 ty) (bor x (uimm32shifted_from_value y))))
      (or_uimm32shifted ty x y))
(rule 4 (lower (has_type (fits_in_64 ty) (bor (uimm32shifted_from_value x) y)))
      (or_uimm32shifted ty y x))

;; Or a register and memory (32/64-bit types).
(rule 1 (lower (has_type (fits_in_64 ty) (bor x (sinkable_load_32_64 y))))
      (or_mem ty x (sink_load y)))
(rule 2 (lower (has_type (fits_in_64 ty) (bor (sinkable_load_32_64 x) y)))
      (or_mem ty y (sink_load x)))

;; Or two vector registers.
(rule 0 (lower (has_type (vr128_ty ty) (bor x y)))
      (vec_or ty x y))

;; Specialized lowerings for `(bor x (bnot y))` which is additionally produced
;; by Cranelift's `bor_not` instruction that is legalized into the simpler
;; forms early on.

;; z15 version using a single instruction.
(rule 7 (lower (has_type (and (mie2_enabled) (fits_in_64 ty)) (bor x (bnot y))))
      (or_not_reg ty x y))
(rule 8 (lower (has_type (and (mie2_enabled) (fits_in_64 ty)) (bor (bnot y) x)))
      (or_not_reg ty x y))

;; Or-not two vector registers.
(rule 9 (lower (has_type (vr128_ty ty) (bor x (bnot y))))
      (vec_or_not ty x y))
(rule 10 (lower (has_type (vr128_ty ty) (bor (bnot y) x)))
      (vec_or_not ty x y))


;;;; Rules for `bxor` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Xor two registers.
(rule -1 (lower (has_type (fits_in_64 ty) (bxor x y)))
      (xor_reg ty x y))

;; Xor a register and an immediate.
(rule 3 (lower (has_type (fits_in_64 ty) (bxor x (uimm32shifted_from_value y))))
      (xor_uimm32shifted ty x y))
(rule 4 (lower (has_type (fits_in_64 ty) (bxor (uimm32shifted_from_value x) y)))
      (xor_uimm32shifted ty y x))

;; Xor a register and memory (32/64-bit types).
(rule 1 (lower (has_type (fits_in_64 ty) (bxor x (sinkable_load_32_64 y))))
      (xor_mem ty x (sink_load y)))
(rule 2 (lower (has_type (fits_in_64 ty) (bxor (sinkable_load_32_64 x) y)))
      (xor_mem ty y (sink_load x)))

;; Xor two vector registers.
(rule 0 (lower (has_type (vr128_ty ty) (bxor x y)))
      (vec_xor ty x y))

;; Specialized lowerings for `(bxor x (bnot y))` which is additionally produced
;; by Cranelift's `bxor_not` instruction that is legalized into the simpler
;; forms early on.

;; z15 version using a single instruction.
(rule 5 (lower (has_type (and (mie2_enabled) (fits_in_64 ty)) (bxor x (bnot y))))
      (not_xor_reg ty x y))
(rule 6 (lower (has_type (and (mie2_enabled) (fits_in_64 ty)) (bxor (bnot y) x)))
      (not_xor_reg ty x y))

;; Xor-not two vector registers.
(rule 7 (lower (has_type (vr128_ty ty) (bxor x (bnot y))))
      (vec_not_xor ty x y))
(rule 8 (lower (has_type (vr128_ty ty) (bxor (bnot y) x)))
      (vec_not_xor ty x y))


;;;; Rules for `bitselect` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; z15 version using a NAND instruction.
(rule 2 (lower (has_type (and (mie2_enabled) (fits_in_64 ty)) (bitselect x y z)))
      (let ((rx Reg x)
            (if_true Reg (and_reg ty y rx))
            (if_false Reg (and_not_reg ty z rx)))
        (or_reg ty if_false if_true)))

;; z14 version using XOR with -1.
(rule 1 (lower (has_type (and (mie2_disabled) (fits_in_64 ty)) (bitselect x y z)))
      (let ((rx Reg x)
            (if_true Reg (and_reg ty y rx))
            (if_false Reg (and_reg ty z (not_reg ty rx))))
        (or_reg ty if_false if_true)))

;; Bitselect vector registers.
(rule (lower (has_type (vr128_ty ty) (bitselect x y z)))
      (vec_select ty y z x))

;; Special-case some float-selection instructions for min/max
(rule 3 (lower (has_type (ty_vec128 ty) (bitselect (bitcast _ (fcmp (FloatCC.LessThan) x y)) x y)))
        (fmin_pseudo_reg ty y x))
(rule 4 (lower (has_type (ty_vec128 ty) (bitselect (bitcast _ (fcmp (FloatCC.LessThan) y x)) x y)))
        (fmax_pseudo_reg ty y x))



;;;; Rules for `bmask` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(rule (lower (has_type ty (bmask x)))
      (lower_bool_to_mask ty (value_nonzero x)))


;;;; Rules for `bitrev` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(rule (lower (has_type ty (bitrev x)))
      (bitrev_bytes ty
        (bitrev_bits 4 0xf0f0_f0f0_f0f0_f0f0 ty
          (bitrev_bits 2 0xcccc_cccc_cccc_cccc ty
            (bitrev_bits 1 0xaaaa_aaaa_aaaa_aaaa ty x)))))

(decl bitrev_bits (u8 u64 Type Reg) Reg)
(rule 1 (bitrev_bits size bitmask (fits_in_64 ty) x)
      (let ((mask Reg (imm ty bitmask))
            (xh Reg (lshl_imm (ty_ext32 ty) x size))
            (xl Reg (lshr_imm (ty_ext32 ty) x size))
            (xh_masked Reg (and_reg ty xh mask))
            (xl_masked Reg (and_reg ty xl (not_reg ty mask))))
        (or_reg ty xh_masked xl_masked)))

(rule (bitrev_bits size bitmask (vr128_ty ty) x)
      (let ((mask Reg (vec_imm_splat $I64X2 bitmask))
            (size_reg Reg (vec_imm_splat $I8X16 (u8_as_u64 size)))
            (xh Reg (vec_lshl_by_bit x size_reg))
            (xl Reg (vec_lshr_by_bit x size_reg)))
        (vec_select ty xh xl mask)))

(decl bitrev_bytes (Type Reg) Reg)
(rule (bitrev_bytes $I8 x) x)
(rule (bitrev_bytes $I16 x) (lshr_imm $I32 (bswap_reg $I32 x) 16))
(rule (bitrev_bytes $I32 x) (bswap_reg $I32 x))
(rule (bitrev_bytes $I64 x) (bswap_reg $I64 x))
(rule (bitrev_bytes $I128 x)
      (vec_permute $I128 x x
                   (vec_imm $I8X16 (imm8x16 15 14 13 12 11 10 9 8
                                            7 6 5 4 3 2 1 0))))


;;;; Rules for `bswap` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(rule (lower (has_type ty (bswap x)))
      (bitrev_bytes ty x))

;;;; Rules for `clz` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; The FLOGR hardware instruction always operates on the full 64-bit register.
;; We can zero-extend smaller types, but then we have to compensate for the
;; additional leading zero bits the instruction will actually see.
(decl clz_offset (Type Reg) Reg)
(rule (clz_offset $I8 x) (add_simm16 $I8 x -56))
(rule (clz_offset $I16 x) (add_simm16 $I16 x -48))
(rule (clz_offset $I32 x) (add_simm16 $I32 x -32))
(rule (clz_offset $I64 x) x)

;; Count leading zeros, via FLOGR on an input zero-extended to 64 bits,
;; with the result compensated for the extra bits.
(rule 1 (lower (has_type (fits_in_64 ty) (clz x)))
      (let ((ext_reg Reg (put_in_reg_zext64 x))
            ;; Ask for a value of 64 in the all-zero 64-bit input case.
            ;; After compensation this will match the expected semantics.
            (clz Reg (clz_reg 64 ext_reg)))
        (clz_offset ty clz)))

;; Count leading zeros, 128-bit full vector.
(rule (lower (has_type $I128 (clz x)))
      (let ((clz_vec Reg (vec_clz $I64X2 x))
            (zero Reg (vec_imm $I64X2 0))
            (clz_hi Reg (vec_permute_dw_imm $I64X2 zero 0 clz_vec 0))
            (clz_lo Reg (vec_permute_dw_imm $I64X2 zero 0 clz_vec 1))
            (clz_sum Reg (vec_add $I64X2 clz_hi clz_lo))
            (mask Reg (vec_cmpeq $I64X2 clz_hi (vec_imm_splat $I64X2 64))))
        (vec_select $I128 clz_sum clz_hi mask)))


;;;; Rules for `cls` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; The result of cls is not supposed to count the sign bit itself, just
;; additional copies of it.  Therefore, when computing cls in terms of clz,
;; we need to subtract one.  Fold this into the offset computation.
(decl cls_offset (Type Reg) Reg)
(rule (cls_offset $I8 x) (add_simm16 $I8 x -57))
(rule (cls_offset $I16 x) (add_simm16 $I16 x -49))
(rule (cls_offset $I32 x) (add_simm16 $I32 x -33))
(rule (cls_offset $I64 x) (add_simm16 $I64 x -1))

;; Count leading sign-bit copies.  We don't have any instruction for that,
;; so we instead count the leading zeros after inverting the input if negative,
;; i.e. computing
;;        cls(x) == clz(x ^ (x >> 63)) - 1
;; where x is the sign-extended input.
(rule 1 (lower (has_type (fits_in_64 ty) (cls x)))
      (let ((ext_reg Reg (put_in_reg_sext64 x))
            (signbit_copies Reg (ashr_imm $I64 ext_reg 63))
            (inv_reg Reg (xor_reg $I64 ext_reg signbit_copies))
            (clz Reg (clz_reg 64 inv_reg)))
        (cls_offset ty clz)))

;; Count leading sign-bit copies, 128-bit full vector.
(rule (lower (has_type $I128 (cls x)))
      (let ((x_reg Reg x)
            (ones Reg (vec_imm_splat $I8X16 255))
            (signbit_copies Reg (vec_ashr_by_bit (vec_ashr_by_byte x_reg ones) ones))
            (inv_reg Reg (vec_xor $I128 x_reg signbit_copies))
            (clz_vec Reg (vec_clz $I64X2 inv_reg))
            (zero Reg (vec_imm $I64X2 0))
            (clz_hi Reg (vec_permute_dw_imm $I64X2 zero 0 clz_vec 0))
            (clz_lo Reg (vec_permute_dw_imm $I64X2 zero 0 clz_vec 1))
            (clz_sum Reg (vec_add $I64X2 clz_hi clz_lo))
            (mask Reg (vec_cmpeq $I64X2 clz_hi (vec_imm_splat $I64X2 64))))
        (vec_add $I128 (vec_select $I128 clz_sum clz_hi mask) ones)))


;;;; Rules for `ctz` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; To count trailing zeros, we find the last bit set in the input via (x & -x),
;; count the leading zeros of that value, and subtract from 63:
;;
;;   ctz(x) == 63 - clz(x & -x)
;;
;; This works for all cases except a zero input, where the above formula would
;; return -1, but we are expected to return the type size.  The compensation
;; for this case is handled differently for 64-bit types vs. smaller types.

;; For smaller types, we simply ensure that the extended 64-bit input is
;; never zero by setting a "guard bit" in the position corresponding to
;; the input type size.  This way the 64-bit algorithm above will handle
;; that case correctly automatically.
(rule 2 (lower (has_type (gpr32_ty ty) (ctz x)))
      (let ((rx Reg (or_uimm16shifted $I64 x (ctz_guardbit ty)))
            (lastbit Reg (and_reg $I64 rx (neg_reg $I64 rx)))
            (clz Reg (clz_reg 64 lastbit)))
        (sub_reg ty (imm ty 63) clz)))

(decl ctz_guardbit (Type) UImm16Shifted)
(rule (ctz_guardbit $I8) (uimm16shifted 256 0))
(rule (ctz_guardbit $I16) (uimm16shifted 1 16))
(rule (ctz_guardbit $I32) (uimm16shifted 1 32))

;; For 64-bit types, the FLOGR instruction will indicate the zero input case
;; via its condition code.  We check for that and replace the instruction
;; result with the value -1 via a conditional move, which will then lead to
;; the correct result after the final subtraction from 63.
(rule 1 (lower (has_type (gpr64_ty _ty) (ctz x)))
      (let ((rx Reg x)
            (lastbit Reg (and_reg $I64 rx (neg_reg $I64 rx)))
            (clz Reg (clz_reg -1 lastbit)))
        (sub_reg $I64 (imm $I64 63) clz)))

;; Count trailing zeros, 128-bit full vector.
(rule 0 (lower (has_type $I128 (ctz x)))
      (let ((ctz_vec Reg (vec_ctz $I64X2 x))
            (zero Reg (vec_imm $I64X2 0))
            (ctz_hi Reg (vec_permute_dw_imm $I64X2 zero 0 ctz_vec 0))
            (ctz_lo Reg (vec_permute_dw_imm $I64X2 zero 0 ctz_vec 1))
            (ctz_sum Reg (vec_add $I64X2 ctz_hi ctz_lo))
            (mask Reg (vec_cmpeq $I64X2 ctz_lo (vec_imm_splat $I64X2 64))))
        (vec_select $I128 ctz_sum ctz_lo mask)))


;;;; Rules for `popcnt` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Population count for 8-bit types is supported by the POPCNT instruction.
(rule (lower (has_type $I8 (popcnt x)))
      (popcnt_byte x))

;; On z15, the POPCNT instruction has a variant to compute a full 64-bit
;; population count, which we also use for 16- and 32-bit types.
(rule -1 (lower (has_type (and (mie2_enabled) (fits_in_64 ty)) (popcnt x)))
      (popcnt_reg (put_in_reg_zext64 x)))

;; On z14, we use the regular POPCNT, which computes the population count
;; of each input byte separately, so we need to accumulate those partial
;; results via a series of log2(type size in bytes) - 1 additions.  We
;; accumulate in the high byte, so that a final right shift will zero out
;; any unrelated bits to give a clean result.  (This does not work with
;; $I16, where we instead accumulate in the low byte and clear high bits
;; via an explicit and operation.)

(rule (lower (has_type (and (mie2_disabled) $I16) (popcnt x)))
      (let ((cnt2 Reg (popcnt_byte x))
            (cnt1 Reg (add_reg $I32 cnt2 (lshr_imm $I32 cnt2 8))))
        (and_uimm16shifted $I32 cnt1 (uimm16shifted 255 0))))

(rule (lower (has_type (and (mie2_disabled) $I32) (popcnt x)))
      (let ((cnt4 Reg (popcnt_byte x))
            (cnt2 Reg (add_reg $I32 cnt4 (lshl_imm $I32 cnt4 16)))
            (cnt1 Reg (add_reg $I32 cnt2 (lshl_imm $I32 cnt2 8))))
        (lshr_imm $I32 cnt1 24)))

(rule (lower (has_type (and (mie2_disabled) $I64) (popcnt x)))
      (let ((cnt8 Reg (popcnt_byte x))
            (cnt4 Reg (add_reg $I64 cnt8 (lshl_imm $I64 cnt8 32)))
            (cnt2 Reg (add_reg $I64 cnt4 (lshl_imm $I64 cnt4 16)))
            (cnt1 Reg (add_reg $I64 cnt2 (lshl_imm $I64 cnt2 8))))
        (lshr_imm $I64 cnt1 56)))

;; Population count for vector types.
(rule 1 (lower (has_type (ty_vec128 ty) (popcnt x)))
      (vec_popcnt ty x))

;; Population count, 128-bit full vector.
(rule (lower (has_type $I128 (popcnt x)))
      (let ((popcnt_vec Reg (vec_popcnt $I64X2 x))
            (zero Reg (vec_imm $I64X2 0))
            (popcnt_hi Reg (vec_permute_dw_imm $I64X2 zero 0 popcnt_vec 0))
            (popcnt_lo Reg (vec_permute_dw_imm $I64X2 zero 0 popcnt_vec 1)))
        (vec_add $I64X2 popcnt_hi popcnt_lo)))


;;;; Rules for `fadd` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Add two registers.
(rule (lower (has_type ty (fadd x y)))
      (fadd_reg ty x y))


;;;; Rules for `fsub` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Subtract two registers.
(rule (lower (has_type ty (fsub x y)))
      (fsub_reg ty x y))


;;;; Rules for `fmul` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Multiply two registers.
(rule (lower (has_type ty (fmul x y)))
      (fmul_reg ty x y))


;;;; Rules for `fdiv` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Divide two registers.
(rule (lower (has_type ty (fdiv x y)))
      (fdiv_reg ty x y))


;;;; Rules for `fmin` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Minimum of two registers.
(rule (lower (has_type ty (fmin x y)))
      (fmin_reg ty x y))


;;;; Rules for `fmax` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Maximum of two registers.
(rule (lower (has_type ty (fmax x y)))
      (fmax_reg ty x y))


;;;; Rules for `fcopysign` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Copysign of two registers.
(rule (lower (has_type $F32 (fcopysign x y)))
      (vec_select $F32 x y (imm $F32 2147483647)))
(rule (lower (has_type $F64 (fcopysign x y)))
      (vec_select $F64 x y (imm $F64 9223372036854775807)))
(rule (lower (has_type $F32X4 (fcopysign x y)))
      (vec_select $F32X4 x y (vec_imm_bit_mask $F32X4 1 31)))
(rule (lower (has_type $F64X2 (fcopysign x y)))
      (vec_select $F64X2 x y (vec_imm_bit_mask $F64X2 1 63)))


;;;; Rules for `fma` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Multiply-and-add of three registers.
(rule (lower (has_type ty (fma x y z)))
      (fma_reg ty x y z))


;;;; Rules for `sqrt` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Square root of a register.
(rule (lower (has_type ty (sqrt x)))
      (sqrt_reg ty x))


;;;; Rules for `fneg` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Negated value of a register.
(rule (lower (has_type ty (fneg x)))
      (fneg_reg ty x))


;;;; Rules for `fabs` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Absolute value of a register.
(rule (lower (has_type ty (fabs x)))
      (fabs_reg ty x))


;;;; Rules for `ceil` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Round value in a register towards positive infinity.
(rule (lower (has_type ty (ceil x)))
      (ceil_reg ty x))


;;;; Rules for `floor` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Round value in a register towards negative infinity.
(rule (lower (has_type ty (floor x)))
      (floor_reg ty x))


;;;; Rules for `trunc` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Round value in a register towards zero.
(rule (lower (has_type ty (trunc x)))
      (trunc_reg ty x))


;;;; Rules for `nearest` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Round value in a register towards nearest.
(rule (lower (has_type ty (nearest x)))
      (nearest_reg ty x))


;;;; Rules for `fpromote` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Promote a register.
(rule (lower (has_type (fits_in_64 dst_ty) (fpromote x @ (value_type src_ty))))
      (fpromote_reg dst_ty src_ty x))


;;;; Rules for `fvpromote_low` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Promote a register.
(rule (lower (has_type $F64X2 (fvpromote_low x @ (value_type $F32X4))))
      (fpromote_reg $F64X2 $F32X4 (vec_merge_low_lane_order $I32X4 x x)))


;;;; Rules for `fdemote` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Demote a register.
(rule (lower (has_type (fits_in_64 dst_ty) (fdemote x @ (value_type src_ty))))
      (fdemote_reg dst_ty src_ty (FpuRoundMode.Current) x))


;;;; Rules for `fvdemote` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Demote a register.
(rule (lower (has_type $F32X4 (fvdemote x @ (value_type $F64X2))))
      (let ((dst Reg (fdemote_reg $F32X4 $F64X2 (FpuRoundMode.Current) x)))
        (vec_pack_lane_order $I64X2 (vec_lshr_imm $I64X2 dst 32)
                                    (vec_imm $I64X2 0))))


;;;; Rules for `fcvt_from_uint` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Convert a 32-bit or smaller unsigned integer to $F32 (z15 instruction).
(rule 1 (lower (has_type $F32
        (fcvt_from_uint x @ (value_type (and (vxrs_ext2_enabled) (fits_in_32 ty))))))
      (fcvt_from_uint_reg $F32 (FpuRoundMode.ToNearestTiesToEven)
                          (put_in_reg_zext32 x)))

;; Convert a 64-bit or smaller unsigned integer to $F32, via an intermediate $F64.
(rule (lower (has_type $F32 (fcvt_from_uint x @ (value_type (fits_in_64 ty)))))
      (fdemote_reg $F32 $F64 (FpuRoundMode.ToNearestTiesToEven)
                   (fcvt_from_uint_reg $F64 (FpuRoundMode.ShorterPrecision)
                                       (put_in_reg_zext64 x))))

;; Convert a 64-bit or smaller unsigned integer to $F64.
(rule (lower (has_type $F64 (fcvt_from_uint x @ (value_type (fits_in_64 ty)))))
      (fcvt_from_uint_reg $F64 (FpuRoundMode.ToNearestTiesToEven)
                          (put_in_reg_zext64 x)))

;; Convert $I32X4 to $F32X4 (z15 instruction).
(rule 1 (lower (has_type (and (vxrs_ext2_enabled) $F32X4)
                       (fcvt_from_uint x @ (value_type $I32X4))))
      (fcvt_from_uint_reg $F32X4 (FpuRoundMode.ToNearestTiesToEven) x))

;; Convert $I32X4 to $F32X4 (via two $F64X2 on z14).
(rule (lower (has_type (and (vxrs_ext2_disabled) $F32X4)
                       (fcvt_from_uint x @ (value_type $I32X4))))
      (vec_permute $F32X4
        (fdemote_reg $F32X4 $F64X2 (FpuRoundMode.ToNearestTiesToEven)
          (fcvt_from_uint_reg $F64X2 (FpuRoundMode.ShorterPrecision)
                              (vec_unpacku_high $I32X4 x)))
        (fdemote_reg $F32X4 $F64X2 (FpuRoundMode.ToNearestTiesToEven)
          (fcvt_from_uint_reg $F64X2 (FpuRoundMode.ShorterPrecision)
                              (vec_unpacku_low $I32X4 x)))
        (vec_imm $I8X16 (imm8x16 0 1 2 3 8 9 10 11 16 17 18 19 24 25 26 27))))

;; Convert $I64X2 to $F64X2.
(rule (lower (has_type $F64X2 (fcvt_from_uint x @ (value_type $I64X2))))
      (fcvt_from_uint_reg $F64X2 (FpuRoundMode.ToNearestTiesToEven) x))


;;;; Rules for `fcvt_from_sint` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Convert a 32-bit or smaller signed integer to $F32 (z15 instruction).
(rule 1 (lower (has_type $F32
        (fcvt_from_sint x @ (value_type (and (vxrs_ext2_enabled) (fits_in_32 ty))))))
      (fcvt_from_sint_reg $F32 (FpuRoundMode.ToNearestTiesToEven)
                          (put_in_reg_sext32 x)))

;; Convert a 64-bit or smaller signed integer to $F32, via an intermediate $F64.
(rule (lower (has_type $F32 (fcvt_from_sint x @ (value_type (fits_in_64 ty)))))
      (fdemote_reg $F32 $F64 (FpuRoundMode.ToNearestTiesToEven)
                   (fcvt_from_sint_reg $F64 (FpuRoundMode.ShorterPrecision)
                                       (put_in_reg_sext64 x))))

;; Convert a 64-bit or smaller signed integer to $F64.
(rule (lower (has_type $F64 (fcvt_from_sint x @ (value_type (fits_in_64 ty)))))
      (fcvt_from_sint_reg $F64 (FpuRoundMode.ToNearestTiesToEven)
                          (put_in_reg_sext64 x)))

;; Convert $I32X4 to $F32X4 (z15 instruction).
(rule 1 (lower (has_type (and (vxrs_ext2_enabled) $F32X4)
                       (fcvt_from_sint x @ (value_type $I32X4))))
      (fcvt_from_sint_reg $F32X4 (FpuRoundMode.ToNearestTiesToEven) x))

;; Convert $I32X4 to $F32X4 (via two $F64X2 on z14).
(rule (lower (has_type (and (vxrs_ext2_disabled) $F32X4)
                       (fcvt_from_sint x @ (value_type $I32X4))))
      (vec_permute $F32X4
        (fdemote_reg $F32X4 $F64X2 (FpuRoundMode.ToNearestTiesToEven)
          (fcvt_from_sint_reg $F64X2 (FpuRoundMode.ShorterPrecision)
                              (vec_unpacks_high $I32X4 x)))
        (fdemote_reg $F32X4 $F64X2 (FpuRoundMode.ToNearestTiesToEven)
          (fcvt_from_sint_reg $F64X2 (FpuRoundMode.ShorterPrecision)
                              (vec_unpacks_low $I32X4 x)))
        (vec_imm $I8X16 (imm8x16 0 1 2 3 8 9 10 11 16 17 18 19 24 25 26 27))))

;; Convert $I64X2 to $F64X2.
(rule (lower (has_type $F64X2 (fcvt_from_sint x @ (value_type $I64X2))))
      (fcvt_from_sint_reg $F64X2 (FpuRoundMode.ToNearestTiesToEven) x))


;;;; Rules for `fcvt_to_uint` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Convert a scalar floating-point value in a register to an unsigned integer.
;; Traps if the input cannot be represented in the output type.
(rule (lower (has_type (fits_in_64 dst_ty)
                       (fcvt_to_uint x @ (value_type src_ty))))
      (let ((src Reg (put_in_reg x))
            ;; First, check whether the input is a NaN, and trap if so.
            (_ Reg (trap_if (fcmp_reg src_ty src src)
                            (floatcc_as_cond (FloatCC.Unordered))
                            (trap_code_bad_conversion_to_integer)))
            ;; Now check whether the input is out of range for the target type.
            (_ Reg (trap_if (fcmp_reg src_ty src (fcvt_to_uint_ub src_ty dst_ty))
                            (floatcc_as_cond (FloatCC.GreaterThanOrEqual))
                            (trap_code_integer_overflow)))
            (_ Reg (trap_if (fcmp_reg src_ty src (fcvt_to_uint_lb src_ty))
                            (floatcc_as_cond (FloatCC.LessThanOrEqual))
                            (trap_code_integer_overflow)))
            ;; Perform the conversion using the larger type size.
            (flt_ty Type (fcvt_flt_ty dst_ty src_ty))
            (src_ext Reg (fpromote_reg flt_ty src_ty src)))
        (fcvt_to_uint_reg flt_ty (FpuRoundMode.ToZero) src_ext)))


;;;; Rules for `fcvt_to_sint` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Convert a scalar floating-point value in a register to a signed integer.
;; Traps if the input cannot be represented in the output type.
(rule (lower (has_type (fits_in_64 dst_ty)
                       (fcvt_to_sint x @ (value_type src_ty))))
      (let ((src Reg (put_in_reg x))
            ;; First, check whether the input is a NaN, and trap if so.
            (_ Reg (trap_if (fcmp_reg src_ty src src)
                            (floatcc_as_cond (FloatCC.Unordered))
                            (trap_code_bad_conversion_to_integer)))
            ;; Now check whether the input is out of range for the target type.
            (_ Reg (trap_if (fcmp_reg src_ty src (fcvt_to_sint_ub src_ty dst_ty))
                            (floatcc_as_cond (FloatCC.GreaterThanOrEqual))
                            (trap_code_integer_overflow)))
            (_ Reg (trap_if (fcmp_reg src_ty src (fcvt_to_sint_lb src_ty dst_ty))
                            (floatcc_as_cond (FloatCC.LessThanOrEqual))
                            (trap_code_integer_overflow)))
            ;; Perform the conversion using the larger type size.
            (flt_ty Type (fcvt_flt_ty dst_ty src_ty))
            (src_ext Reg (fpromote_reg flt_ty src_ty src)))
        ;; Perform the conversion.
        (fcvt_to_sint_reg flt_ty (FpuRoundMode.ToZero) src_ext)))


;;;; Rules for `fcvt_to_uint_sat` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Convert a scalar floating-point value in a register to an unsigned integer.
(rule -1 (lower (has_type (fits_in_64 dst_ty)
                       (fcvt_to_uint_sat x @ (value_type src_ty))))
      (let ((src Reg (put_in_reg x))
            ;; Perform the conversion using the larger type size.
            (flt_ty Type (fcvt_flt_ty dst_ty src_ty))
            (int_ty Type (fcvt_int_ty dst_ty src_ty))
            (src_ext Reg (fpromote_reg flt_ty src_ty src))
            (dst Reg (fcvt_to_uint_reg flt_ty (FpuRoundMode.ToZero) src_ext)))
        ;; Clamp the output to the destination type bounds.
        (uint_sat_reg dst_ty int_ty dst)))

;; Convert $F32X4 to $I32X4 (z15 instruction).
(rule 1 (lower (has_type (and (vxrs_ext2_enabled) $I32X4)
                       (fcvt_to_uint_sat x @ (value_type $F32X4))))
      (fcvt_to_uint_reg $F32X4 (FpuRoundMode.ToZero) x))

;; Convert $F32X4 to $I32X4 (via two $F64X2 on z14).
(rule (lower (has_type (and (vxrs_ext2_disabled) $I32X4)
                       (fcvt_to_uint_sat x @ (value_type $F32X4))))
      (vec_pack_usat $I64X2
        (fcvt_to_uint_reg $F64X2 (FpuRoundMode.ToZero)
          (fpromote_reg $F64X2 $F32X4 (vec_merge_high $I32X4 x x)))
        (fcvt_to_uint_reg $F64X2 (FpuRoundMode.ToZero)
          (fpromote_reg $F64X2 $F32X4 (vec_merge_low $I32X4 x x)))))

;; Convert $F64X2 to $I64X2.
(rule (lower (has_type $I64X2 (fcvt_to_uint_sat x @ (value_type $F64X2))))
      (fcvt_to_uint_reg $F64X2 (FpuRoundMode.ToZero) x))


;;;; Rules for `fcvt_to_sint_sat` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Convert a scalar floating-point value in a register to a signed integer.
(rule -1 (lower (has_type (fits_in_64 dst_ty)
                       (fcvt_to_sint_sat x @ (value_type src_ty))))
      (let ((src Reg (put_in_reg x))
            ;; Perform the conversion using the larger type size.
            (flt_ty Type (fcvt_flt_ty dst_ty src_ty))
            (int_ty Type (fcvt_int_ty dst_ty src_ty))
            (src_ext Reg (fpromote_reg flt_ty src_ty src))
            (dst Reg (fcvt_to_sint_reg flt_ty (FpuRoundMode.ToZero) src_ext))
            ;; In most special cases, the Z instruction already yields the
            ;; result expected by Cranelift semantics.  The only exception
            ;; it the case where the input was a NaN.  We explicitly check
            ;; for that and force the output to 0 in that case.
            (sat Reg (with_flags_reg (fcmp_reg src_ty src src)
                                     (cmov_imm int_ty
                                       (floatcc_as_cond (FloatCC.Unordered)) 0 dst))))
        ;; Clamp the output to the destination type bounds.
        (sint_sat_reg dst_ty int_ty sat)))

;; Convert $F32X4 to $I32X4 (z15 instruction).
(rule 1 (lower (has_type (and (vxrs_ext2_enabled) $I32X4)
                       (fcvt_to_sint_sat src @ (value_type $F32X4))))
      ;; See above for why we need to handle NaNs specially.
      (vec_select $I32X4
        (fcvt_to_sint_reg $F32X4 (FpuRoundMode.ToZero) src)
        (vec_imm $I32X4 0) (vec_fcmpeq $F32X4 src src)))

;; Convert $F32X4 to $I32X4 (via two $F64X2 on z14).
(rule (lower (has_type (and (vxrs_ext2_disabled) $I32X4)
                       (fcvt_to_sint_sat src @ (value_type $F32X4))))
      ;; See above for why we need to handle NaNs specially.
      (vec_select $I32X4
        (vec_pack_ssat $I64X2
          (fcvt_to_sint_reg $F64X2 (FpuRoundMode.ToZero)
            (fpromote_reg $F64X2 $F32X4 (vec_merge_high $I32X4 src src)))
          (fcvt_to_sint_reg $F64X2 (FpuRoundMode.ToZero)
            (fpromote_reg $F64X2 $F32X4 (vec_merge_low $I32X4 src src))))
        (vec_imm $I32X4 0) (vec_fcmpeq $F32X4 src src)))

;; Convert $F64X2 to $I64X2.
(rule (lower (has_type $I64X2 (fcvt_to_sint_sat src @ (value_type $F64X2))))
      ;; See above for why we need to handle NaNs specially.
      (vec_select $I64X2
        (fcvt_to_sint_reg $F64X2 (FpuRoundMode.ToZero) src)
        (vec_imm $I64X2 0) (vec_fcmpeq $F64X2 src src)))


;;;; Rules for `bitcast` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Reinterpret a 64-bit integer value as floating-point.
(rule (lower (has_type $F64 (bitcast _ x @ (value_type $I64))))
      (vec_insert_lane_undef $F64X2 x 0 (zero_reg)))

;; Reinterpret a 64-bit floating-point value as integer.
(rule (lower (has_type $I64 (bitcast _ x @ (value_type $F64))))
      (vec_extract_lane $F64X2 x 0 (zero_reg)))

;; Reinterpret a 32-bit integer value as floating-point.
(rule (lower (has_type $F32 (bitcast _ x @ (value_type $I32))))
      (vec_insert_lane_undef $F32X4 x 0 (zero_reg)))

;; Reinterpret a 32-bit floating-point value as integer.
(rule (lower (has_type $I32 (bitcast _ x @ (value_type $F32))))
      (vec_extract_lane $F32X4 x 0 (zero_reg)))

;; Bitcast between types residing in GPRs is a no-op.
(rule 1 (lower (has_type (gpr32_ty _)
                         (bitcast _ x @ (value_type (gpr32_ty _)))))
      x)
(rule 2 (lower (has_type (gpr64_ty _)
                         (bitcast _ x @ (value_type (gpr64_ty _)))))
      x)

;; Bitcast between types residing in FPRs is a no-op.
(rule 3 (lower (has_type (ty_scalar_float _)
                         (bitcast _ x @ (value_type (ty_scalar_float _)))))
      x)

;; Bitcast between types residing in VRs is a no-op if lane count is unchanged.
(rule 5 (lower (has_type (multi_lane bits count)
                         (bitcast _ x @ (value_type (multi_lane bits count)))))
      x)

;; Bitcast between types residing in VRs with different lane counts is a
;; no-op if the operation's MemFlags indicate a byte order compatible with
;; the current lane order.  Otherwise, lane elements need to be swapped,
;; first in the input type, and then again in the output type.  This could
;; be optimized further, but we don't bother at the moment since due to our
;; choice of lane order depending on the current function ABI, this case will
;; currently never arise in practice.
(rule 4 (lower (has_type (vr128_ty out_ty)
                         (bitcast flags x @ (value_type (vr128_ty in_ty)))))
      (abi_vec_elt_rev (lane_order_from_memflags flags) out_ty
        (abi_vec_elt_rev (lane_order_from_memflags flags) in_ty x)))


;;;; Rules for `insertlane` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Insert vector lane from general-purpose register.
(rule 1 (lower (insertlane x @ (value_type ty)
                         y @ (value_type in_ty)
                         (u8_from_uimm8 idx)))
      (if (ty_int_ref_scalar_64 in_ty))
      (vec_insert_lane ty x y (be_lane_idx ty idx) (zero_reg)))

;; Insert vector lane from floating-point register.
(rule 0 (lower (insertlane x @ (value_type ty)
                         y @ (value_type (ty_scalar_float _))
                         (u8_from_uimm8 idx)))
      (vec_move_lane_and_insert ty x (be_lane_idx ty idx) y 0))

;; Insert vector lane from another vector lane.
(rule 2 (lower (insertlane x @ (value_type ty)
                         (extractlane y (u8_from_uimm8 src_idx))
                         (u8_from_uimm8 dst_idx)))
      (vec_move_lane_and_insert ty x (be_lane_idx ty dst_idx)
                                   y (be_lane_idx ty src_idx)))

;; Insert vector lane from signed 16-bit immediate.
(rule 3 (lower (insertlane x @ (value_type ty) (i16_from_value y)
                         (u8_from_uimm8 idx)))
      (vec_insert_lane_imm ty x y (be_lane_idx ty idx)))

;; Insert vector lane from big-endian memory.
(rule 4 (lower (insertlane x @ (value_type ty) (sinkable_load y)
                         (u8_from_uimm8 idx)))
      (vec_load_lane ty x (sink_load y) (be_lane_idx ty idx)))

;; Insert vector lane from little-endian memory.
(rule 5 (lower (insertlane x @ (value_type ty) (sinkable_load_little y)
                         (u8_from_uimm8 idx)))
      (vec_load_lane_little ty x (sink_load y) (be_lane_idx ty idx)))


;; Helper to extract one lane from a vector and insert it into another.
(decl vec_move_lane_and_insert (Type Reg u8 Reg u8) Reg)

;; For 64-bit elements we always use VPDI.
(rule (vec_move_lane_and_insert ty @ (multi_lane 64 _) dst 0 src src_idx)
      (vec_permute_dw_imm ty src src_idx dst 1))
(rule (vec_move_lane_and_insert ty @ (multi_lane 64 _) dst 1 src src_idx)
      (vec_permute_dw_imm ty dst 0 src src_idx))

;; If source and destination index are the same, use vec_select.
(rule -1 (vec_move_lane_and_insert ty dst idx src idx)
      (vec_select ty src
                  dst (vec_imm_byte_mask ty (lane_byte_mask ty idx))))

;; Otherwise replicate source first and then use vec_select.
(rule -2 (vec_move_lane_and_insert ty dst dst_idx src src_idx)
      (vec_select ty (vec_replicate_lane ty src src_idx)
                  dst (vec_imm_byte_mask ty (lane_byte_mask ty dst_idx))))


;; Helper to implement a generic little-endian variant of vec_load_lane.
(decl vec_load_lane_little (Type Reg MemArg u8) Reg)

;; 8-byte little-endian loads can be performed via a normal load.
(rule (vec_load_lane_little ty @ (multi_lane 8 _) dst addr lane_imm)
      (vec_load_lane ty dst addr lane_imm))

;; On z15, we have instructions to perform little-endian loads.
(rule 1 (vec_load_lane_little (and (vxrs_ext2_enabled)
                                 ty @ (multi_lane 16 _)) dst addr lane_imm)
      (vec_load_lane_rev ty dst addr lane_imm))
(rule 1 (vec_load_lane_little (and (vxrs_ext2_enabled)
                                 ty @ (multi_lane 32 _)) dst addr lane_imm)
      (vec_load_lane_rev ty dst addr lane_imm))
(rule 1 (vec_load_lane_little (and (vxrs_ext2_enabled)
                                 ty @ (multi_lane 64 _)) dst addr lane_imm)
      (vec_load_lane_rev ty dst addr lane_imm))

;; On z14, use a little-endian load to GPR followed by vec_insert_lane.
(rule (vec_load_lane_little (and (vxrs_ext2_disabled)
                                 ty @ (multi_lane 16 _)) dst addr lane_imm)
      (vec_insert_lane ty dst (loadrev16 addr) lane_imm (zero_reg)))
(rule (vec_load_lane_little (and (vxrs_ext2_disabled)
                                 ty @ (multi_lane 32 _)) dst addr lane_imm)
      (vec_insert_lane ty dst (loadrev32 addr) lane_imm (zero_reg)))
(rule (vec_load_lane_little (and (vxrs_ext2_disabled)
                                 ty @ (multi_lane 64 _)) dst addr lane_imm)
      (vec_insert_lane ty dst (loadrev64 addr) lane_imm (zero_reg)))

;; Helper to implement a generic little-endian variant of vec_load_lane_undef.
(decl vec_load_lane_little_undef (Type MemArg u8) Reg)

;; 8-byte little-endian loads can be performed via a normal load.
(rule (vec_load_lane_little_undef ty @ (multi_lane 8 _) addr lane_imm)
      (vec_load_lane_undef ty addr lane_imm))

;; On z15, we have instructions to perform little-endian loads.
(rule 1 (vec_load_lane_little_undef (and (vxrs_ext2_enabled)
                                       ty @ (multi_lane 16 _)) addr lane_imm)
      (vec_load_lane_rev_undef ty addr lane_imm))
(rule 1 (vec_load_lane_little_undef (and (vxrs_ext2_enabled)
                                       ty @ (multi_lane 32 _)) addr lane_imm)
      (vec_load_lane_rev_undef ty addr lane_imm))
(rule 1 (vec_load_lane_little_undef (and (vxrs_ext2_enabled)
                                       ty @ (multi_lane 64 _)) addr lane_imm)
      (vec_load_lane_rev_undef ty addr lane_imm))

;; On z14, use a little-endian load to GPR followed by vec_insert_lane_undef.
(rule (vec_load_lane_little_undef (and (vxrs_ext2_disabled)
                                       ty @ (multi_lane 16 _)) addr lane_imm)
      (vec_insert_lane_undef ty (loadrev16 addr) lane_imm (zero_reg)))
(rule (vec_load_lane_little_undef (and (vxrs_ext2_disabled)
                                       ty @ (multi_lane 32 _)) addr lane_imm)
      (vec_insert_lane_undef ty (loadrev32 addr) lane_imm (zero_reg)))
(rule (vec_load_lane_little_undef (and (vxrs_ext2_disabled)
                                       ty @ (multi_lane 64 _)) addr lane_imm)
      (vec_insert_lane_undef ty (loadrev64 addr) lane_imm (zero_reg)))


;;;; Rules for `extractlane` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Extract vector lane to general-purpose register.
(rule 1 (lower (has_type out_ty
                       (extractlane x @ (value_type ty) (u8_from_uimm8 idx))))
      (if (ty_int_ref_scalar_64 out_ty))
      (vec_extract_lane ty x (be_lane_idx ty idx) (zero_reg)))

;; Extract vector lane to floating-point register.
(rule 0 (lower (has_type (ty_scalar_float _)
                       (extractlane x @ (value_type ty) (u8_from_uimm8 idx))))
      (vec_replicate_lane ty x (be_lane_idx ty idx)))

;; Extract vector lane and store to big-endian memory.
(rule 6 (lower (store flags @ (bigendian)
                    (extractlane x @ (value_type ty) (u8_from_uimm8 idx))
                    addr offset))
      (side_effect (vec_store_lane ty x
                     (lower_address flags addr offset) (be_lane_idx ty idx))))

;; Extract vector lane and store to little-endian memory.
(rule 5 (lower (store flags @ (littleendian)
                    (extractlane x @ (value_type ty) (u8_from_uimm8 idx))
                    addr offset))
      (side_effect (vec_store_lane_little ty x
                     (lower_address flags addr offset) (be_lane_idx ty idx))))


;; Helper to implement a generic little-endian variant of vec_store_lane.
(decl vec_store_lane_little (Type Reg MemArg u8) SideEffectNoResult)

;; 8-byte little-endian stores can be performed via a normal store.
(rule (vec_store_lane_little ty @ (multi_lane 8 _) src addr lane_imm)
      (vec_store_lane ty src addr lane_imm))

;; On z15, we have instructions to perform little-endian stores.
(rule 1 (vec_store_lane_little (and (vxrs_ext2_enabled)
                                  ty @ (multi_lane 16 _)) src addr lane_imm)
      (vec_store_lane_rev ty src addr lane_imm))
(rule 1 (vec_store_lane_little (and (vxrs_ext2_enabled)
                                  ty @ (multi_lane 32 _)) src addr lane_imm)
      (vec_store_lane_rev ty src addr lane_imm))
(rule 1 (vec_store_lane_little (and (vxrs_ext2_enabled)
                                  ty @ (multi_lane 64 _)) src addr lane_imm)
      (vec_store_lane_rev ty src addr lane_imm))

;; On z14, use vec_extract_lane followed by a little-endian store from GPR.
(rule (vec_store_lane_little (and (vxrs_ext2_disabled)
                                  ty @ (multi_lane 16 _)) src addr lane_imm)
      (storerev16 (vec_extract_lane ty src lane_imm (zero_reg)) addr))
(rule (vec_store_lane_little (and (vxrs_ext2_disabled)
                                  ty @ (multi_lane 32 _)) src addr lane_imm)
      (storerev32 (vec_extract_lane ty src lane_imm (zero_reg)) addr))
(rule (vec_store_lane_little (and (vxrs_ext2_disabled)
                                  ty @ (multi_lane 64 _)) src addr lane_imm)
      (storerev64 (vec_extract_lane ty src lane_imm (zero_reg)) addr))


;;;; Rules for `splat` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Load replicated value from general-purpose register.
(rule 1 (lower (has_type ty (splat x @ (value_type in_ty))))
      (if (ty_int_ref_scalar_64 in_ty))
      (vec_replicate_lane ty (vec_insert_lane_undef ty x 0 (zero_reg)) 0))

;; Load replicated value from floating-point register.
(rule 0 (lower (has_type ty (splat
                             x @ (value_type (ty_scalar_float _)))))
      (vec_replicate_lane ty x 0))

;; Load replicated value from vector lane.
(rule 2 (lower (has_type ty (splat (extractlane x (u8_from_uimm8 idx)))))
      (vec_replicate_lane ty x (be_lane_idx ty idx)))

;; Load replicated 16-bit immediate value.
(rule 3 (lower (has_type ty (splat (i16_from_value x))))
      (vec_imm_replicate ty x))

;; Load replicated value from big-endian memory.
(rule 4 (lower (has_type ty (splat (sinkable_load x))))
      (vec_load_replicate ty (sink_load x)))

;; Load replicated value from little-endian memory.
(rule 5 (lower (has_type ty (splat (sinkable_load_little x))))
      (vec_load_replicate_little ty (sink_load x)))


;; Helper to implement a generic little-endian variant of vec_load_replicate
(decl vec_load_replicate_little (Type MemArg) Reg)

;; 8-byte little-endian loads can be performed via a normal load.
(rule (vec_load_replicate_little ty @ (multi_lane 8 _) addr)
      (vec_load_replicate ty addr))

;; On z15, we have instructions to perform little-endian loads.
(rule 1 (vec_load_replicate_little (and (vxrs_ext2_enabled)
                                 ty @ (multi_lane 16 _)) addr)
      (vec_load_replicate_rev ty addr))
(rule 1 (vec_load_replicate_little (and (vxrs_ext2_enabled)
                                 ty @ (multi_lane 32 _)) addr)
      (vec_load_replicate_rev ty addr))
(rule 1 (vec_load_replicate_little (and (vxrs_ext2_enabled)
                                 ty @ (multi_lane 64 _)) addr)
      (vec_load_replicate_rev ty addr))

;; On z14, use a little-endian load (via GPR) and replicate.
(rule (vec_load_replicate_little (and (vxrs_ext2_disabled)
                                 ty @ (multi_lane 16 _)) addr)
      (vec_replicate_lane ty (vec_load_lane_little_undef ty addr 0) 0))
(rule (vec_load_replicate_little (and (vxrs_ext2_disabled)
                                 ty @ (multi_lane 32 _)) addr)
      (vec_replicate_lane ty (vec_load_lane_little_undef ty addr 0) 0))
(rule (vec_load_replicate_little (and (vxrs_ext2_disabled)
                                 ty @ (multi_lane 64 _)) addr)
      (vec_replicate_lane ty (vec_load_lane_little_undef ty addr 0) 0))


;;;; Rules for `scalar_to_vector` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Load scalar value from general-purpose register.
(rule 1 (lower (has_type ty (scalar_to_vector
                             x @ (value_type in_ty))))
      (if (ty_int_ref_scalar_64 in_ty))
      (vec_insert_lane ty (vec_imm ty 0) x (be_lane_idx ty 0) (zero_reg)))

;; Load scalar value from floating-point register.
(rule 0 (lower (has_type ty (scalar_to_vector
                             x @ (value_type (ty_scalar_float _)))))
      (vec_move_lane_and_zero ty (be_lane_idx ty 0) x 0))

;; Load scalar value from vector lane.
(rule 2 (lower (has_type ty (scalar_to_vector
                            (extractlane x (u8_from_uimm8 idx)))))
      (vec_move_lane_and_zero ty (be_lane_idx ty 0) x (be_lane_idx ty idx)))

;; Load scalar 16-bit immediate value.
(rule 3 (lower (has_type ty (scalar_to_vector (i16_from_value x))))
      (vec_insert_lane_imm ty (vec_imm ty 0) x (be_lane_idx ty 0)))

;; Load scalar value from big-endian memory.
(rule 4 (lower (has_type ty (scalar_to_vector (sinkable_load x))))
      (vec_load_lane ty (vec_imm ty 0) (sink_load x) (be_lane_idx ty 0)))

;; Load scalar value lane from little-endian memory.
(rule 5 (lower (has_type ty (scalar_to_vector (sinkable_load_little x))))
      (vec_load_lane_little ty (vec_imm ty 0) (sink_load x) (be_lane_idx ty 0)))


;; Helper to extract one lane from a vector and insert it into a zero vector.
(decl vec_move_lane_and_zero (Type u8 Reg u8) Reg)

;; For 64-bit elements we always use VPDI.
(rule (vec_move_lane_and_zero ty @ (multi_lane 64 _) 0 src src_idx)
      (vec_permute_dw_imm ty src src_idx (vec_imm ty 0) 0))
(rule (vec_move_lane_and_zero ty @ (multi_lane 64 _) 1 src src_idx)
      (vec_permute_dw_imm ty (vec_imm ty 0) 0 src src_idx))

;; If source and destination index are the same, simply mask to this lane.
(rule -1 (vec_move_lane_and_zero ty idx src idx)
      (vec_and ty src
               (vec_imm_byte_mask ty (lane_byte_mask ty idx))))

;; Otherwise replicate source first and then mask to the lane.
(rule -2 (vec_move_lane_and_zero ty dst_idx src src_idx)
      (vec_and ty (vec_replicate_lane ty src src_idx)
               (vec_imm_byte_mask ty (lane_byte_mask ty dst_idx))))


;;;; Rules for `shuffle` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; General case: use vec_permute and then mask off zero lanes.
(rule -2 (lower (shuffle x y (shuffle_mask permute_mask and_mask)))
      (vec_and $I8X16 (vec_imm_byte_mask $I8X16 and_mask)
               (vec_permute $I8X16 x y (vec_imm $I8X16 permute_mask))))

;; If the pattern has no zero lanes, just a vec_permute suffices.
(rule -1 (lower (shuffle x y (shuffle_mask permute_mask 65535)))
      (vec_permute $I8X16 x y (vec_imm $I8X16 permute_mask)))

;; Special patterns that can be implemented via MERGE HIGH.
(rule (lower (shuffle x y (shuffle_mask (imm8x16 0 1 2 3 4 5 6 7 16 17 18 19 20 21 22 23) 65535)))
      (vec_merge_high $I64X2 x y))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 0 1 2 3 16 17 18 19 4 5 6 7 20 21 22 23) 65535)))
      (vec_merge_high $I32X4 x y))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 0 1 16 17 2 3 18 19 4 5 20 21 6 7 22 23) 65535)))
      (vec_merge_high $I16X8 x y))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 0 16 1 17 2 18 3 19 4 20 5 21 6 22 7 23) 65535)))
      (vec_merge_high $I8X16 x y))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 16 17 18 19 20 21 22 23 0 1 2 3 4 5 6 7) 65535)))
      (vec_merge_high $I64X2 y x))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 16 17 18 19 0 1 2 3 20 21 22 23 4 5 6 7) 65535)))
      (vec_merge_high $I32X4 y x))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 16 17 0 1 18 19 2 3 20 21 4 5 22 23 6 7) 65535)))
      (vec_merge_high $I16X8 y x))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 16 0 17 1 18 2 19 3 20 4 21 5 22 6 23 7) 65535)))
      (vec_merge_high $I8X16 y x))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7) 65535)))
      (vec_merge_high $I64X2 x x))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 0 1 2 3 0 1 2 3 4 5 6 7 4 5 6 7) 65535)))
      (vec_merge_high $I32X4 x x))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 0 1 0 1 2 3 2 3 4 5 4 5 6 7 6 7) 65535)))
      (vec_merge_high $I16X8 x x))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 0 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7) 65535)))
      (vec_merge_high $I8X16 x x))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 16 17 18 19 20 21 22 23 16 17 18 19 20 21 22 23) 65535)))
      (vec_merge_high $I64X2 y y))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 16 17 18 19 16 17 18 19 20 21 22 23 20 21 22 23) 65535)))
      (vec_merge_high $I32X4 y y))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 16 17 16 17 18 19 18 19 20 21 20 21 22 23 22 23) 65535)))
      (vec_merge_high $I16X8 y y))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 16 16 17 17 18 18 19 19 20 20 21 21 22 22 23 23) 65535)))
      (vec_merge_high $I8X16 y y))

;; Special patterns that can be implemented via MERGE LOW.
(rule (lower (shuffle x y (shuffle_mask (imm8x16 8 9 10 11 12 13 14 15 24 25 26 27 28 29 30 31) 65535)))
      (vec_merge_low $I64X2 x y))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 8 9 10 11 24 25 26 27 12 13 14 15 28 29 30 31) 65535)))
      (vec_merge_low $I32X4 x y))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 8 9 24 25 10 11 26 27 12 13 28 29 14 15 30 31) 65535)))
      (vec_merge_low $I16X8 x y))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 8 24 9 25 10 26 11 27 12 28 13 29 14 30 15 31) 65535)))
      (vec_merge_low $I8X16 x y))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 24 25 26 27 28 29 30 31 8 9 10 11 12 13 14 15) 65535)))
      (vec_merge_low $I64X2 y x))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 24 25 26 27 8 9 10 11 28 29 30 31 12 13 14 15) 65535)))
      (vec_merge_low $I32X4 y x))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 24 25 8 9 26 27 10 11 28 29 12 13 30 31 14 15) 65535)))
      (vec_merge_low $I16X8 y x))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 24 8 25 9 26 10 27 11 28 12 29 13 30 14 31 15) 65535)))
      (vec_merge_low $I8X16 y x))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 8 9 10 11 12 13 14 15 8 9 10 11 12 13 14 15) 65535)))
      (vec_merge_low $I64X2 x x))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 8 9 10 11 8 9 10 11 12 13 14 15 12 13 14 15) 65535)))
      (vec_merge_low $I32X4 x x))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 8 9 8 9 10 11 10 11 12 13 12 13 14 15 14 15) 65535)))
      (vec_merge_low $I16X8 x x))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 8 8 9 9 10 10 11 11 12 12 13 13 14 14 15 15) 65535)))
      (vec_merge_low $I8X16 x x))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 24 25 26 27 28 29 30 31 24 25 26 27 28 29 30 31) 65535)))
      (vec_merge_low $I64X2 y y))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 24 25 26 27 24 25 26 27 28 29 30 31 28 29 30 31) 65535)))
      (vec_merge_low $I32X4 y y))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 24 25 24 25 26 27 26 27 28 29 28 29 30 31 30 31) 65535)))
      (vec_merge_low $I16X8 y y))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 24 24 25 25 26 26 27 27 28 28 29 29 30 30 31 31) 65535)))
      (vec_merge_low $I8X16 y y))

;; Special patterns that can be implemented via PACK.
(rule (lower (shuffle x y (shuffle_mask (imm8x16 4 5 6 7 12 13 14 15 20 21 22 23 28 29 30 31) 65535)))
      (vec_pack $I64X2 x y))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 2 3 6 7 10 11 14 15 18 19 22 23 26 27 30 31) 65535)))
      (vec_pack $I32X4 x y))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31) 65535)))
      (vec_pack $I16X8 x y))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 20 21 22 23 28 29 30 31 4 5 6 7 12 13 14 15) 65535)))
      (vec_pack $I64X2 y x))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 18 19 22 23 26 27 30 31 2 3 6 7 10 11 14 15) 65535)))
      (vec_pack $I32X4 y x))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 17 19 21 23 25 27 29 31 1 3 5 7 9 11 13 15) 65535)))
      (vec_pack $I16X8 y x))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 4 5 6 7 12 13 14 15 4 5 6 7 12 13 14 15) 65535)))
      (vec_pack $I64X2 x x))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 2 3 6 7 10 11 14 15 2 3 6 7 10 11 14 15) 65535)))
      (vec_pack $I32X4 x x))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 1 3 5 7 9 11 13 15 1 3 5 7 9 11 13 15) 65535)))
      (vec_pack $I16X8 x x))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 20 21 22 23 28 29 30 31 20 21 22 23 28 29 30 31) 65535)))
      (vec_pack $I64X2 y y))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 18 19 22 23 26 27 30 31 18 19 22 23 26 27 30 31) 65535)))
      (vec_pack $I32X4 y y))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 17 19 21 23 25 27 29 31 17 19 21 23 25 27 29 31) 65535)))
      (vec_pack $I16X8 y y))

;; Special patterns that can be implemented via UNPACK HIGH.
(rule (lower (shuffle x y (shuffle_mask (imm8x16 _ _ _ _ 0 1 2 3 _ _ _ _ 4 5 6 7) 3855)))
      (vec_unpacku_high $I32X4 x))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 _ _ 0 1 _ _ 2 3 _ _ 4 5 _ _ 6 7) 13107)))
      (vec_unpacku_high $I16X8 x))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 _ 0 _ 1 _ 2 _ 3 _ 4 _ 5 _ 6 _ 7) 21845)))
      (vec_unpacku_high $I8X16 x))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 _ _ _ _ 16 17 18 19 _ _ _ _ 20 21 22 23) 3855)))
      (vec_unpacku_high $I32X4 y))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 _ _ 16 17 _ _ 18 19 _ _ 20 21 _ _ 22 23) 13107)))
      (vec_unpacku_high $I16X8 y))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 _ 16 _ 17 _ 18 _ 19 _ 20 _ 21 _ 22 _ 23) 21845)))
      (vec_unpacku_high $I8X16 y))

;; Special patterns that can be implemented via UNPACK LOW.
(rule (lower (shuffle x y (shuffle_mask (imm8x16 _ _ _ _ 8 9 10 11 _ _ _ _ 12 13 14 15) 3855)))
      (vec_unpacku_low $I32X4 x))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 _ _ 8 9 _ _ 10 11 _ _ 12 13 _ _ 14 15) 13107)))
      (vec_unpacku_low $I16X8 x))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 _ 8 _ 9 _ 10 _ 11 _ 12 _ 13 _ 14 _ 15) 21845)))
      (vec_unpacku_low $I8X16 x))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 _ _ _ _ 24 25 26 27 _ _ _ _ 28 29 30 31) 3855)))
      (vec_unpacku_low $I32X4 y))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 _ _ 24 25 _ _ 26 27 _ _ 28 29 _ _ 30 31) 13107)))
      (vec_unpacku_low $I16X8 y))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 _ 24 _ 25 _ 26 _ 27 _ 28 _ 29 _ 30 _ 31) 21845)))
      (vec_unpacku_low $I8X16 y))

;; Special patterns that can be implemented via PERMUTE DOUBLEWORD IMMEDIATE.
(rule (lower (shuffle x y (shuffle_mask (imm8x16 0 1 2 3 4 5 6 7 24 25 26 27 28 29 30 31) 65535)))
      (vec_permute_dw_imm $I8X16 x 0 y 1))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23) 65535)))
      (vec_permute_dw_imm $I8X16 x 1 y 0))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 16 17 18 19 20 21 22 23 8 9 10 11 12 13 14 15) 65535)))
      (vec_permute_dw_imm $I8X16 y 0 x 1))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 24 25 26 27 28 29 30 31 0 1 2 3 4 5 6 7) 65535)))
      (vec_permute_dw_imm $I8X16 y 1 x 0))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15) 65535)))
      (vec_permute_dw_imm $I8X16 x 0 x 1))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 8 9 10 11 12 13 14 15 0 1 2 3 4 5 6 7) 65535)))
      (vec_permute_dw_imm $I8X16 x 1 x 0))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31) 65535)))
      (vec_permute_dw_imm $I8X16 y 0 y 1))
(rule (lower (shuffle x y (shuffle_mask (imm8x16 24 25 26 27 28 29 30 31 16 17 18 19 20 21 22 23) 65535)))
      (vec_permute_dw_imm $I8X16 y 1 y 0))


;;;; Rules for `swizzle` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; When using big-endian lane order, the lane mask is mostly correct, but we
;; need to handle mask elements outside the range 0..15 by zeroing the lane.
;;
;; To do so efficiently, we compute:
;;     permute-lane-element := umin (16, swizzle-lane-element)
;; and pass a zero vector as second operand to the permute instruction.

(rule 1 (lower (has_type (ty_vec128 ty) (swizzle x y)))
      (if-let (LaneOrder.BigEndian) (lane_order))
      (vec_permute ty x (vec_imm ty 0)
         (vec_umin $I8X16 (vec_imm_splat $I8X16 16) y)))

;; When using little-endian lane order, in addition to zeroing (as above),
;; we need to convert from little-endian to big-endian lane numbering.
;;
;; To do so efficiently, we compute:
;;     permute-lane-element := umax (239, ~ swizzle-lane-element)
;; which has the following effect:
;;     elements 0 .. 15 --> 255 .. 240 (i.e. 31 .. 16 mod 32)
;;     everything else --> 239 (i.e. 15 mod 32)
;;
;; Then, we can use a single permute instruction with
;;     a zero vector as first operand (covering lane 15)
;;     the input vector as second operand (covering lanes 16 .. 31)
;; to implement the required swizzle semantics.

(rule (lower (has_type (ty_vec128 ty) (swizzle x y)))
      (if-let (LaneOrder.LittleEndian) (lane_order))
      (vec_permute ty (vec_imm ty 0) x
         (vec_umax $I8X16 (vec_imm_splat $I8X16 239)
           (vec_not $I8X16 y))))


;;;; Rules for `stack_addr` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Load the address of a stack slot.
(rule (lower (has_type ty (stack_addr stack_slot offset)))
      (stack_addr_impl ty stack_slot offset))


;;;; Rules for `func_addr` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Load the address of a function, target reachable via PC-relative instruction.
(rule 1 (lower (func_addr (func_ref_data _ name (reloc_distance_near))))
      (load_addr (memarg_symbol name 0 (memflags_trusted))))

;; Load the address of a function, general case.
(rule (lower (func_addr (func_ref_data _ name _)))
      (load_symbol_reloc (SymbolReloc.Absolute name 0)))


;;;; Rules for `symbol_value` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Load the address of a symbol, target reachable via PC-relative instruction.
(rule 1 (lower (symbol_value (symbol_value_data name (reloc_distance_near)
                                              off)))
      (if-let offset (memarg_symbol_offset off))
      (load_addr (memarg_symbol name offset (memflags_trusted))))

;; Load the address of a symbol, general case.
(rule (lower (symbol_value (symbol_value_data name _ offset)))
      (load_symbol_reloc (SymbolReloc.Absolute name offset)))


;;;; Rules for `tls_value` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Load the address of a TLS symbol (ELF general-dynamic model).
(rule (lower (tls_value (symbol_value_data name _ 0)))
      (if (tls_model_is_elf_gd))
      (let ((symbol SymbolReloc (SymbolReloc.TlsGd name))
            (got Reg (load_addr (memarg_got)))
            (got_offset Reg (load_symbol_reloc symbol))
            (tls_offset Reg (lib_call_tls_get_offset got got_offset symbol)))
        (add_reg $I64 tls_offset (thread_pointer))))

;; Helper to perform a call to the __tls_get_offset library routine.
(decl lib_call_tls_get_offset (Reg Reg SymbolReloc) Reg)
(rule (lib_call_tls_get_offset got got_offset symbol)
      (let ((tls_offset WritableReg (temp_writable_reg $I64))
            (_ Unit (abi_for_elf_tls_get_offset))
            (_ Unit (emit (MInst.ElfTlsGetOffset tls_offset got got_offset symbol))))
        tls_offset))

(decl abi_for_elf_tls_get_offset () Unit)
(extern constructor abi_for_elf_tls_get_offset abi_for_elf_tls_get_offset)

;; Helper to extract the current thread pointer from %a0/%a1.
(decl thread_pointer () Reg)
(rule (thread_pointer)
      (insert_ar (lshl_imm $I64 (load_ar 0) 32) 1))


;;;; Rules for `load` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Load 8-bit integers.
(rule (lower (has_type $I8 (load flags addr offset)))
      (zext32_mem $I8 (lower_address flags addr offset)))

;; Load 16-bit big-endian integers.
(rule (lower (has_type $I16 (load flags @ (bigendian) addr offset)))
      (zext32_mem $I16 (lower_address flags addr offset)))

;; Load 16-bit little-endian integers.
(rule -1 (lower (has_type $I16 (load flags @ (littleendian) addr offset)))
      (loadrev16 (lower_address flags addr offset)))

;; Load 32-bit big-endian integers.
(rule (lower (has_type $I32 (load flags @ (bigendian) addr offset)))
      (load32 (lower_address flags addr offset)))

;; Load 32-bit little-endian integers.
(rule -1 (lower (has_type $I32 (load flags @ (littleendian) addr offset)))
      (loadrev32 (lower_address flags addr offset)))

;; Load 64-bit big-endian integers.
(rule (lower (has_type $I64 (load flags @ (bigendian) addr offset)))
      (load64 (lower_address flags addr offset)))

;; Load 64-bit little-endian integers.
(rule -1 (lower (has_type $I64 (load flags @ (littleendian) addr offset)))
      (loadrev64 (lower_address flags addr offset)))

;; Load 32-bit big-endian floating-point values (as vector lane).
(rule (lower (has_type $F32 (load flags @ (bigendian) addr offset)))
      (vec_load_lane_undef $F32X4 (lower_address flags addr offset) 0))

;; Load 32-bit little-endian floating-point values (as vector lane).
(rule -1 (lower (has_type $F32 (load flags @ (littleendian) addr offset)))
      (vec_load_lane_little_undef $F32X4 (lower_address flags addr offset) 0))

;; Load 64-bit big-endian floating-point values (as vector lane).
(rule (lower (has_type $F64 (load flags @ (bigendian) addr offset)))
      (vec_load_lane_undef $F64X2 (lower_address flags addr offset) 0))

;; Load 64-bit little-endian floating-point values (as vector lane).
(rule -1 (lower (has_type $F64 (load flags @ (littleendian) addr offset)))
      (vec_load_lane_little_undef $F64X2 (lower_address flags addr offset) 0))

;; Load 128-bit big-endian vector values, BE lane order - direct load.
(rule 4 (lower (has_type (vr128_ty ty) (load flags @ (bigendian) addr offset)))
      (if-let (LaneOrder.BigEndian) (lane_order))
      (vec_load ty (lower_address flags addr offset)))

;; Load 128-bit little-endian vector values, BE lane order - byte-reversed load.
(rule 3 (lower (has_type (vr128_ty ty) (load flags @ (littleendian) addr offset)))
      (if-let (LaneOrder.BigEndian) (lane_order))
      (vec_load_byte_rev ty flags addr offset))

;; Load 128-bit big-endian vector values, LE lane order - element-reversed load.
(rule 2 (lower (has_type (vr128_ty ty) (load flags @ (bigendian) addr offset)))
      (if-let (LaneOrder.LittleEndian) (lane_order))
      (vec_load_elt_rev ty flags addr offset))

;; Load 128-bit little-endian vector values, LE lane order - fully-reversed load.
(rule 1 (lower (has_type (vr128_ty ty) (load flags @ (littleendian) addr offset)))
      (if-let (LaneOrder.LittleEndian) (lane_order))
      (vec_load_full_rev ty flags addr offset))


;; Helper to perform a 128-bit full-vector byte-reversed load.
(decl vec_load_full_rev (Type MemFlags Value Offset32) Reg)

;; Full-vector byte-reversed load via single instruction on z15.
(rule 1 (vec_load_full_rev (and (vxrs_ext2_enabled) (vr128_ty ty)) flags addr offset)
      (vec_loadrev ty (lower_address flags addr offset)))

;; Full-vector byte-reversed load via GPRs on z14.
(rule (vec_load_full_rev (and (vxrs_ext2_disabled) (vr128_ty ty)) flags addr offset)
      (let ((lo_addr MemArg (lower_address_bias flags addr offset 0))
            (hi_addr MemArg (lower_address_bias flags addr offset 8))
            (lo_val Reg (loadrev64 lo_addr))
            (hi_val Reg (loadrev64 hi_addr)))
        (mov_to_vec128 ty hi_val lo_val)))


;; Helper to perform an element-wise byte-reversed load.
(decl vec_load_byte_rev (Type MemFlags Value Offset32) Reg)

;; Element-wise byte-reversed 1x128-bit load is a full byte-reversed load.
(rule -1 (vec_load_byte_rev $I128 flags addr offset)
      (vec_load_full_rev $I128 flags addr offset))

;; Element-wise byte-reversed 16x8-bit load is a direct load.
(rule (vec_load_byte_rev ty @ (multi_lane 8 16) flags addr offset)
      (vec_load ty (lower_address flags addr offset)))

;; Element-wise byte-reversed load via single instruction on z15.
(rule 1 (vec_load_byte_rev (and (vxrs_ext2_enabled) ty @ (multi_lane 64 2))
                        flags addr offset)
      (vec_load_byte64rev ty (lower_address flags addr offset)))
(rule 1 (vec_load_byte_rev (and (vxrs_ext2_enabled) ty @ (multi_lane 32 4))
                        flags addr offset)
      (vec_load_byte32rev ty (lower_address flags addr offset)))
(rule 1 (vec_load_byte_rev (and (vxrs_ext2_enabled) ty @ (multi_lane 16 8))
                        flags addr offset)
      (vec_load_byte16rev ty (lower_address flags addr offset)))

;; Element-wise byte-reversed load as element-swapped byte-reversed load on z14.
(rule (vec_load_byte_rev (and (vxrs_ext2_disabled) ty @ (multi_lane 64 2))
                        flags addr offset)
      (vec_elt_rev ty (vec_load_full_rev ty flags addr offset)))
(rule (vec_load_byte_rev (and (vxrs_ext2_disabled) ty @ (multi_lane 32 4))
                        flags addr offset)
      (vec_elt_rev ty (vec_load_full_rev ty flags addr offset)))
(rule (vec_load_byte_rev (and (vxrs_ext2_disabled) ty @ (multi_lane 16 8))
                        flags addr offset)
      (vec_elt_rev ty (vec_load_full_rev ty flags addr offset)))


;; Helper to perform an element-reversed load.
(decl vec_load_elt_rev (Type MemFlags Value Offset32) Reg)

;; Element-reversed 1x128-bit load is a direct load.
;; For 1x128-bit types, this is a direct load.
(rule -1 (vec_load_elt_rev $I128 flags addr offset)
      (vec_load $I128 (lower_address flags addr offset)))

;; Element-reversed 16x8-bit load is a full byte-reversed load.
(rule (vec_load_elt_rev ty @ (multi_lane 8 16) flags addr offset)
      (vec_load_full_rev ty flags addr offset))

;; Element-reversed load via single instruction on z15.
(rule 1 (vec_load_elt_rev (and (vxrs_ext2_enabled) ty @ (multi_lane 64 2))
                        flags addr offset)
      (vec_load_elt64rev ty (lower_address flags addr offset)))
(rule 1 (vec_load_elt_rev (and (vxrs_ext2_enabled) ty @ (multi_lane 32 4))
                        flags addr offset)
      (vec_load_elt32rev ty (lower_address flags addr offset)))
(rule 1 (vec_load_elt_rev (and (vxrs_ext2_enabled) ty @ (multi_lane 16 8))
                        flags addr offset)
      (vec_load_elt16rev ty (lower_address flags addr offset)))

;; Element-reversed load as element-swapped direct load on z14.
(rule (vec_load_elt_rev (and (vxrs_ext2_disabled) ty @ (multi_lane 64 2))
                        flags addr offset)
      (vec_elt_rev ty (vec_load ty (lower_address flags addr offset))))
(rule (vec_load_elt_rev (and (vxrs_ext2_disabled) ty @ (multi_lane 32 4))
                        flags addr offset)
      (vec_elt_rev ty (vec_load ty (lower_address flags addr offset))))
(rule (vec_load_elt_rev (and (vxrs_ext2_disabled) ty @ (multi_lane 16 8))
                        flags addr offset)
      (vec_elt_rev ty (vec_load ty (lower_address flags addr offset))))


;;;; Rules for `uload8` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; 16- or 32-bit target types.
(rule (lower (has_type (gpr32_ty _ty) (uload8 flags addr offset)))
      (zext32_mem $I8 (lower_address flags addr offset)))

;; 64-bit target types.
(rule 1 (lower (has_type (gpr64_ty _ty) (uload8 flags addr offset)))
      (zext64_mem $I8 (lower_address flags addr offset)))


;;;; Rules for `sload8` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; 16- or 32-bit target types.
(rule (lower (has_type (gpr32_ty _ty) (sload8 flags addr offset)))
      (sext32_mem $I8 (lower_address flags addr offset)))

;; 64-bit target types.
(rule 1 (lower (has_type (gpr64_ty _ty) (sload8 flags addr offset)))
      (sext64_mem $I8 (lower_address flags addr offset)))


;;;; Rules for `uload16` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; 32-bit target type, big-endian source value.
(rule 3 (lower (has_type (gpr32_ty _ty)
                       (uload16 flags @ (bigendian) addr offset)))
      (zext32_mem $I16 (lower_address flags addr offset)))

;; 32-bit target type, little-endian source value (via explicit extension).
(rule 1 (lower (has_type (gpr32_ty _ty)
                       (uload16 flags @ (littleendian) addr offset)))
      (let ((reg16 Reg (loadrev16 (lower_address flags addr offset))))
        (zext32_reg $I16 reg16)))

;; 64-bit target type, big-endian source value.
(rule 4 (lower (has_type (gpr64_ty _ty)
                       (uload16 flags @ (bigendian) addr offset)))
      (zext64_mem $I16 (lower_address flags addr offset)))

;; 64-bit target type, little-endian source value (via explicit extension).
(rule 2 (lower (has_type (gpr64_ty _ty)
                       (uload16 flags @ (littleendian) addr offset)))
      (let ((reg16 Reg (loadrev16 (lower_address flags addr offset))))
        (zext64_reg $I16 reg16)))


;;;; Rules for `sload16` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; 32-bit target type, big-endian source value.
(rule 2 (lower (has_type (gpr32_ty _ty)
                       (sload16 flags @ (bigendian) addr offset)))
      (sext32_mem $I16 (lower_address flags addr offset)))

;; 32-bit target type, little-endian source value (via explicit extension).
(rule 0 (lower (has_type (gpr32_ty _ty)
                       (sload16 flags @ (littleendian) addr offset)))
      (let ((reg16 Reg (loadrev16 (lower_address flags addr offset))))
        (sext32_reg $I16 reg16)))

;; 64-bit target type, big-endian source value.
(rule 3 (lower (has_type (gpr64_ty _ty)
                       (sload16 flags @ (bigendian) addr offset)))
      (sext64_mem $I16 (lower_address flags addr offset)))

;; 64-bit target type, little-endian source value (via explicit extension).
(rule 1 (lower (has_type (gpr64_ty _ty)
                       (sload16 flags @ (littleendian) addr offset)))
      (let ((reg16 Reg (loadrev16 (lower_address flags addr offset))))
        (sext64_reg $I16 reg16)))


;;;; Rules for `uload32` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; 64-bit target type, big-endian source value.
(rule 1 (lower (has_type (gpr64_ty _ty)
                       (uload32 flags @ (bigendian) addr offset)))
      (zext64_mem $I32 (lower_address flags addr offset)))

;; 64-bit target type, little-endian source value (via explicit extension).
(rule (lower (has_type (gpr64_ty _ty)
                       (uload32 flags @ (littleendian) addr offset)))
      (let ((reg32 Reg (loadrev32 (lower_address flags addr offset))))
        (zext64_reg $I32 reg32)))


;;;; Rules for `sload32` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; 64-bit target type, big-endian source value.
(rule 1 (lower (has_type (gpr64_ty _ty)
                       (sload32 flags @ (bigendian) addr offset)))
      (sext64_mem $I32 (lower_address flags addr offset)))

;; 64-bit target type, little-endian source value (via explicit extension).
(rule (lower (has_type (gpr64_ty _ty)
                       (sload32 flags @ (littleendian) addr offset)))
      (let ((reg32 Reg (loadrev32 (lower_address flags addr offset))))
        (sext64_reg $I32 reg32)))


;;;; Rules for `uloadNxM` and `sloadNxM` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Unsigned 8->16 bit extension.
(rule (lower (has_type $I16X8 (uload8x8 flags addr offset)))
      (vec_unpacku_high $I8X16 (load_v64 $I8X16 flags addr offset)))

;; Signed 8->16 bit extension.
(rule (lower (has_type $I16X8 (sload8x8 flags addr offset)))
      (vec_unpacks_high $I8X16 (load_v64 $I8X16 flags addr offset)))

;; Unsigned 16->32 bit extension.
(rule (lower (has_type $I32X4 (uload16x4 flags addr offset)))
      (vec_unpacku_high $I16X8 (load_v64 $I16X8 flags addr offset)))

;; Signed 16->32 bit extension.
(rule (lower (has_type $I32X4 (sload16x4 flags addr offset)))
      (vec_unpacks_high $I16X8 (load_v64 $I16X8 flags addr offset)))

;; Unsigned 32->64 bit extension.
(rule (lower (has_type $I64X2 (uload32x2 flags addr offset)))
      (vec_unpacku_high $I32X4 (load_v64 $I32X4 flags addr offset)))

;; Signed 32->64 bit extension.
(rule (lower (has_type $I64X2 (sload32x2 flags addr offset)))
      (vec_unpacks_high $I32X4 (load_v64 $I32X4 flags addr offset)))


;; Helper to load a 64-bit half-size vector from memory.
(decl load_v64 (Type MemFlags Value Offset32) Reg)

;; Any big-endian source value, BE lane order.
(rule -1 (load_v64 _ flags @ (bigendian) addr offset)
      (if-let (LaneOrder.BigEndian) (lane_order))
      (vec_load_lane_undef $I64X2 (lower_address flags addr offset) 0))

;; Any little-endian source value, LE lane order.
(rule -2 (load_v64 _ flags @ (littleendian) addr offset)
      (if-let (LaneOrder.LittleEndian) (lane_order))
      (vec_load_lane_little_undef $I64X2 (lower_address flags addr offset) 0))

;; Big-endian or little-endian 8x8-bit source value, BE lane order.
(rule (load_v64 (multi_lane 8 16) flags addr offset)
      (if-let (LaneOrder.BigEndian) (lane_order))
      (vec_load_lane_undef $I64X2 (lower_address flags addr offset) 0))

;; Big-endian or little-endian 8x8-bit source value, LE lane order.
(rule 1 (load_v64 (multi_lane 8 16) flags addr offset)
      (if-let (LaneOrder.LittleEndian) (lane_order))
      (vec_load_lane_little_undef $I64X2 (lower_address flags addr offset) 0))

;; Little-endian 4x16-bit source value, BE lane order.
(rule (load_v64 (multi_lane 16 8) flags @ (littleendian) addr offset)
      (if-let (LaneOrder.BigEndian) (lane_order))
      (vec_rot_imm $I16X8
        (vec_load_lane_undef $I64X2 (lower_address flags addr offset) 0) 8))

;; Big-endian 4x16-bit source value, LE lane order.
(rule 1 (load_v64 (multi_lane 16 8) flags @ (bigendian) addr offset)
      (if-let (LaneOrder.LittleEndian) (lane_order))
      (vec_rot_imm $I16X8
        (vec_load_lane_little_undef $I64X2 (lower_address flags addr offset) 0) 8))

;; Little-endian 2x32-bit source value, BE lane order.
(rule (load_v64 (multi_lane 32 4) flags @ (littleendian) addr offset)
      (if-let (LaneOrder.BigEndian) (lane_order))
      (vec_rot_imm $I64X2
        (vec_load_lane_little_undef $I64X2 (lower_address flags addr offset) 0) 32))

;; Big-endian 2x32-bit source value, LE lane order.
(rule 1 (load_v64 (multi_lane 32 4) flags @ (bigendian) addr offset)
      (if-let (LaneOrder.LittleEndian) (lane_order))
      (vec_rot_imm $I64X2
        (vec_load_lane_undef $I64X2 (lower_address flags addr offset) 0) 32))


;;;; Rules for `store` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; The actual store logic for integer types is identical for the `store`,
;; `istoreNN`, and `atomic_store` instructions, so we share common helpers.

;; Store 8-bit integer type, main lowering entry point.
(rule (lower (store flags val @ (value_type $I8) addr offset))
      (side_effect (istore8_impl flags val addr offset)))

;; Store 16-bit integer type, main lowering entry point.
(rule (lower (store flags val @ (value_type $I16) addr offset))
      (side_effect (istore16_impl flags val addr offset)))

;; Store 32-bit integer type, main lowering entry point.
(rule (lower (store flags val @ (value_type $I32) addr offset))
      (side_effect (istore32_impl flags val addr offset)))

;; Store 64-bit integer type, main lowering entry point.
(rule (lower (store flags val @ (value_type $I64) addr offset))
      (side_effect (istore64_impl flags val addr offset)))

;; Store 32-bit big-endian floating-point type (as vector lane).
(rule -1 (lower (store flags @ (bigendian)
                    val @ (value_type $F32) addr offset))
      (side_effect (vec_store_lane $F32X4 val
                                   (lower_address flags addr offset) 0)))

;; Store 32-bit little-endian floating-point type (as vector lane).
(rule (lower (store flags @ (littleendian)
                    val @ (value_type $F32) addr offset))
      (side_effect (vec_store_lane_little $F32X4 val
                                          (lower_address flags addr offset) 0)))

;; Store 64-bit big-endian floating-point type (as vector lane).
(rule -1 (lower (store flags @ (bigendian)
                    val @ (value_type $F64) addr offset))
      (side_effect (vec_store_lane $F64X2 val
                                   (lower_address flags addr offset) 0)))

;; Store 64-bit little-endian floating-point type (as vector lane).
(rule (lower (store flags @ (littleendian)
                    val @ (value_type $F64) addr offset))
      (side_effect (vec_store_lane_little $F64X2 val
                                          (lower_address flags addr offset) 0)))

;; Store 128-bit big-endian vector type, BE lane order - direct store.
(rule 4 (lower (store flags @ (bigendian)
                    val @ (value_type (vr128_ty ty)) addr offset))
      (if-let (LaneOrder.BigEndian) (lane_order))
      (side_effect (vec_store val (lower_address flags addr offset))))

;; Store 128-bit little-endian vector type, BE lane order - byte-reversed store.
(rule 3 (lower (store flags @ (littleendian)
                    val @ (value_type (vr128_ty ty)) addr offset))
      (if-let (LaneOrder.BigEndian) (lane_order))
      (side_effect (vec_store_byte_rev ty val flags addr offset)))

;; Store 128-bit big-endian vector type, LE lane order - element-reversed store.
(rule 2 (lower (store flags @ (bigendian)
                    val @ (value_type (vr128_ty ty)) addr offset))
      (if-let (LaneOrder.LittleEndian) (lane_order))
      (side_effect (vec_store_elt_rev ty val flags addr offset)))

;; Store 128-bit little-endian vector type, LE lane order - fully-reversed store.
(rule 1 (lower (store flags @ (littleendian)
                    val @ (value_type (vr128_ty ty)) addr offset))
      (if-let (LaneOrder.LittleEndian) (lane_order))
      (side_effect (vec_store_full_rev ty val flags addr offset)))


;; Helper to perform a 128-bit full-vector byte-reversed store.
(decl vec_store_full_rev (Type Reg MemFlags Value Offset32) SideEffectNoResult)

;; Full-vector byte-reversed store via single instruction on z15.
(rule 1 (vec_store_full_rev (vxrs_ext2_enabled) val flags addr offset)
      (vec_storerev val (lower_address flags addr offset)))

;; Full-vector byte-reversed store via GPRs on z14.
(rule (vec_store_full_rev (vxrs_ext2_disabled) val flags addr offset)
      (let ((lo_addr MemArg (lower_address_bias flags addr offset 0))
            (hi_addr MemArg (lower_address_bias flags addr offset 8))
            (lo_val Reg (vec_extract_lane $I64X2 val 1 (zero_reg)))
            (hi_val Reg (vec_extract_lane $I64X2 val 0 (zero_reg))))
        (side_effect_concat (storerev64 lo_val lo_addr)
                            (storerev64 hi_val hi_addr))))


;; Helper to perform an element-wise byte-reversed store.
(decl vec_store_byte_rev (Type Reg MemFlags Value Offset32) SideEffectNoResult)

;; Element-wise byte-reversed 1x128-bit store is a full byte-reversed store.
(rule -1 (vec_store_byte_rev $I128 val flags addr offset)
      (vec_store_full_rev $I128 val flags addr offset))

;; Element-wise byte-reversed 16x8-bit store is a direct store.
(rule (vec_store_byte_rev (multi_lane 8 16) val flags addr offset)
      (vec_store val (lower_address flags addr offset)))

;; Element-wise byte-reversed store via single instruction on z15.
(rule 1 (vec_store_byte_rev (and (vxrs_ext2_enabled) ty @ (multi_lane 64 2))
                          val flags addr offset)
      (vec_store_byte64rev val (lower_address flags addr offset)))
(rule 1 (vec_store_byte_rev (and (vxrs_ext2_enabled) ty @ (multi_lane 32 4))
                          val flags addr offset)
      (vec_store_byte32rev val (lower_address flags addr offset)))
(rule 1 (vec_store_byte_rev (and (vxrs_ext2_enabled) ty @ (multi_lane 16 8))
                          val flags addr offset)
      (vec_store_byte16rev val (lower_address flags addr offset)))

;; Element-wise byte-reversed load as element-swapped byte-reversed store on z14.
(rule (vec_store_byte_rev (and (vxrs_ext2_disabled) ty @ (multi_lane 64 2))
                          val flags addr offset)
      (vec_store_full_rev ty (vec_elt_rev ty val) flags addr offset))
(rule (vec_store_byte_rev (and (vxrs_ext2_disabled) ty @ (multi_lane 32 4))
                          val flags addr offset)
      (vec_store_full_rev ty (vec_elt_rev ty val) flags addr offset))
(rule (vec_store_byte_rev (and (vxrs_ext2_disabled) ty @ (multi_lane 16 8))
                          val flags addr offset)
      (vec_store_full_rev ty (vec_elt_rev ty val) flags addr offset))


;; Helper to perform an element-reversed store.
(decl vec_store_elt_rev (Type Reg MemFlags Value Offset32) SideEffectNoResult)

;; Element-reversed 1x128-bit store is a direct store.
(rule -1 (vec_store_elt_rev $I128 val flags addr offset)
      (vec_store val (lower_address flags addr offset)))

;; Element-reversed 16x8-bit store is a full byte-reversed store.
(rule (vec_store_elt_rev ty @ (multi_lane 8 16) val flags addr offset)
      (vec_store_full_rev ty val flags addr offset))

;; Element-reversed store via single instruction on z15.
(rule 1 (vec_store_elt_rev (and (vxrs_ext2_enabled) ty @ (multi_lane 64 2))
                         val flags addr offset)
      (vec_store_elt64rev val (lower_address flags addr offset)))
(rule 1 (vec_store_elt_rev (and (vxrs_ext2_enabled) ty @ (multi_lane 32 4))
                         val flags addr offset)
      (vec_store_elt32rev val (lower_address flags addr offset)))
(rule 1 (vec_store_elt_rev (and (vxrs_ext2_enabled) ty @ (multi_lane 16 8))
                         val flags addr offset)
      (vec_store_elt16rev val (lower_address flags addr offset)))

;; Element-reversed store as element-swapped direct store on z14.
(rule (vec_store_elt_rev (and (vxrs_ext2_disabled) ty @ (multi_lane 64 2))
                         val flags addr offset)
      (vec_store (vec_elt_rev ty val) (lower_address flags addr offset)))
(rule (vec_store_elt_rev (and (vxrs_ext2_disabled) ty @ (multi_lane 32 4))
                         val flags addr offset)
      (vec_store (vec_elt_rev ty val) (lower_address flags addr offset)))
(rule (vec_store_elt_rev (and (vxrs_ext2_disabled) ty @ (multi_lane 16 8))
                         val flags addr offset)
      (vec_store (vec_elt_rev ty val) (lower_address flags addr offset)))


;;;; Rules for 8-bit integer stores ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Main `istore8` lowering entry point, dispatching to the helper.
(rule (lower (istore8 flags val addr offset))
      (side_effect (istore8_impl flags val addr offset)))

;; Helper to store 8-bit integer types.
(decl istore8_impl (MemFlags Value Value Offset32) SideEffectNoResult)

;; Store 8-bit integer types, register input.
(rule (istore8_impl flags val addr offset)
      (store8 (put_in_reg val) (lower_address flags addr offset)))

;; Store 8-bit integer types, immediate input.
(rule 1 (istore8_impl flags (u8_from_value imm) addr offset)
      (store8_imm imm (lower_address flags addr offset)))


;;;; Rules for 16-bit integer stores ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Main `istore16` lowering entry point, dispatching to the helper.
(rule (lower (istore16 flags val addr offset))
      (side_effect (istore16_impl flags val addr offset)))

;; Helper to store 16-bit integer types.
(decl istore16_impl (MemFlags Value Value Offset32) SideEffectNoResult)

;; Store 16-bit big-endian integer types, register input.
(rule 2 (istore16_impl flags @ (bigendian) val addr offset)
      (store16 (put_in_reg val) (lower_address flags addr offset)))

;; Store 16-bit little-endian integer types, register input.
(rule 0 (istore16_impl flags @ (littleendian) val addr offset)
      (storerev16 (put_in_reg val) (lower_address flags addr offset)))

;; Store 16-bit big-endian integer types, immediate input.
(rule 3 (istore16_impl flags @ (bigendian) (i16_from_value imm) addr offset)
      (store16_imm imm (lower_address flags addr offset)))

;; Store 16-bit little-endian integer types, immediate input.
(rule 1 (istore16_impl flags @ (littleendian) (i16_from_swapped_value imm) addr offset)
      (store16_imm imm (lower_address flags addr offset)))


;;;; Rules for 32-bit integer stores ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Main `istore32` lowering entry point, dispatching to the helper.
(rule (lower (istore32 flags val addr offset))
      (side_effect (istore32_impl flags val addr offset)))

;; Helper to store 32-bit integer types.
(decl istore32_impl (MemFlags Value Value Offset32) SideEffectNoResult)

;; Store 32-bit big-endian integer types, register input.
(rule 1 (istore32_impl flags @ (bigendian) val addr offset)
      (store32 (put_in_reg val) (lower_address flags addr offset)))

;; Store 32-bit big-endian integer types, immediate input.
(rule 2 (istore32_impl flags @ (bigendian) (i16_from_value imm) addr offset)
      (store32_simm16 imm (lower_address flags addr offset)))

;; Store 32-bit little-endian integer types.
(rule 0 (istore32_impl flags @ (littleendian) val addr offset)
      (storerev32 (put_in_reg val) (lower_address flags addr offset)))


;;;; Rules for 64-bit integer stores ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Helper to store 64-bit integer types.
(decl istore64_impl (MemFlags Value Value Offset32) SideEffectNoResult)

;; Store 64-bit big-endian integer types, register input.
(rule 1 (istore64_impl flags @ (bigendian) val addr offset)
      (store64 (put_in_reg val) (lower_address flags addr offset)))

;; Store 64-bit big-endian integer types, immediate input.
(rule 2 (istore64_impl flags @ (bigendian) (i16_from_value imm) addr offset)
      (store64_simm16 imm (lower_address flags addr offset)))

;; Store 64-bit little-endian integer types.
(rule 0 (istore64_impl flags @ (littleendian) val addr offset)
      (storerev64 (put_in_reg val) (lower_address flags addr offset)))


;;;; Rules for `atomic_rmw` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Atomic operations that do not require a compare-and-swap loop.

;; Atomic AND for 32/64-bit big-endian types, using a single instruction.
(rule 1 (lower (has_type (ty_32_or_64 ty)
                (atomic_rmw flags @ (bigendian) (AtomicRmwOp.And) addr src)))
      (atomic_rmw_and ty (put_in_reg src)
                      (lower_address flags addr (zero_offset))))

;; Atomic AND for 32/64-bit big-endian types, using byte-swapped input/output.
(rule (lower (has_type (ty_32_or_64 ty)
               (atomic_rmw flags @ (littleendian) (AtomicRmwOp.And) addr src)))
      (bswap_reg ty (atomic_rmw_and ty (bswap_reg ty (put_in_reg src))
                                    (lower_address flags addr (zero_offset)))))

;; Atomic OR for 32/64-bit big-endian types, using a single instruction.
(rule 1 (lower (has_type (ty_32_or_64 ty)
               (atomic_rmw flags @ (bigendian) (AtomicRmwOp.Or) addr src)))
      (atomic_rmw_or ty (put_in_reg src)
                     (lower_address flags addr (zero_offset))))

;; Atomic OR for 32/64-bit little-endian types, using byte-swapped input/output.
(rule (lower (has_type (ty_32_or_64 ty)
               (atomic_rmw flags @ (littleendian) (AtomicRmwOp.Or) addr src)))
      (bswap_reg ty (atomic_rmw_or ty (bswap_reg ty (put_in_reg src))
                                   (lower_address flags addr (zero_offset)))))

;; Atomic XOR for 32/64-bit big-endian types, using a single instruction.
(rule 1 (lower (has_type (ty_32_or_64 ty)
               (atomic_rmw flags @ (bigendian) (AtomicRmwOp.Xor) addr src)))
      (atomic_rmw_xor ty (put_in_reg src)
                      (lower_address flags addr (zero_offset))))

;; Atomic XOR for 32/64-bit little-endian types, using byte-swapped input/output.
(rule (lower (has_type (ty_32_or_64 ty)
               (atomic_rmw flags @ (littleendian) (AtomicRmwOp.Xor) addr src)))
      (bswap_reg ty (atomic_rmw_xor ty (bswap_reg ty (put_in_reg src))
                                    (lower_address flags addr (zero_offset)))))

;; Atomic ADD for 32/64-bit big-endian types, using a single instruction.
(rule (lower (has_type (ty_32_or_64 ty)
               (atomic_rmw flags @ (bigendian) (AtomicRmwOp.Add) addr src)))
      (atomic_rmw_add ty (put_in_reg src)
                      (lower_address flags addr (zero_offset))))

;; Atomic SUB for 32/64-bit big-endian types, using atomic ADD with negated input.
(rule (lower (has_type (ty_32_or_64 ty)
               (atomic_rmw flags @ (bigendian) (AtomicRmwOp.Sub) addr src)))
      (atomic_rmw_add ty (neg_reg ty (put_in_reg src))
                      (lower_address flags addr (zero_offset))))


;; Atomic operations that require a compare-and-swap loop.

;; Operations for 32/64-bit types can use a fullword compare-and-swap loop.
(rule -1 (lower (has_type (ty_32_or_64 ty) (atomic_rmw flags op addr src)))
      (let ((src_reg Reg (put_in_reg src))
            (addr_reg Reg (put_in_reg addr))
            ;; Create body of compare-and-swap loop.
            (ib VecMInstBuilder (inst_builder_new))
            (val0 Reg (writable_reg_to_reg (casloop_val_reg)))
            (val1 Reg (atomic_rmw_body ib ty flags op
                        (casloop_tmp_reg) val0 src_reg)))
        ;; Emit compare-and-swap loop and extract final result.
        (casloop ib ty flags addr_reg val1)))

;; Operations for 8/16-bit types must operate on the surrounding aligned word.
(rule -2 (lower (has_type (ty_8_or_16 ty) (atomic_rmw flags op addr src)))
      (let ((src_reg Reg (put_in_reg src))
            (addr_reg Reg (put_in_reg addr))
            ;; Prepare access to surrounding aligned word.
            (bitshift Reg (casloop_bitshift addr_reg))
            (aligned_addr Reg (casloop_aligned_addr addr_reg))
            ;; Create body of compare-and-swap loop.
            (ib VecMInstBuilder (inst_builder_new))
            (val0 Reg (writable_reg_to_reg (casloop_val_reg)))
            (val1 Reg (casloop_rotate_in ib ty flags bitshift val0))
            (val2 Reg (atomic_rmw_body ib ty flags op
                        (casloop_tmp_reg) val1 src_reg))
            (val3 Reg (casloop_rotate_out ib ty flags bitshift val2)))
        ;; Emit compare-and-swap loop and extract final result.
        (casloop_subword ib ty flags aligned_addr bitshift val3)))

;; Loop bodies for atomic read-modify-write operations.
(decl atomic_rmw_body (VecMInstBuilder Type MemFlags AtomicRmwOp
                       WritableReg Reg Reg) Reg)

;; Loop bodies for 32-/64-bit atomic XCHG operations.
;; Simply use the source (possibly byte-swapped) as new target value.
(rule 2 (atomic_rmw_body ib (ty_32_or_64 ty) (bigendian)
                       (AtomicRmwOp.Xchg) tmp val src)
      src)
(rule 1 (atomic_rmw_body ib (ty_32_or_64 ty) (littleendian)
                       (AtomicRmwOp.Xchg) tmp val src)
      (bswap_reg ty src))

;; Loop bodies for 32-/64-bit atomic NAND operations.
;; On z15 this can use the NN(G)RK instruction.  On z14, perform an And
;; operation and invert the result.  In the little-endian case, we can
;; simply byte-swap the source operand.
(rule 4 (atomic_rmw_body ib (and (mie2_enabled) (ty_32_or_64 ty)) (bigendian)
                       (AtomicRmwOp.Nand) tmp val src)
      (push_alu_reg ib (aluop_not_and ty) tmp val src))
(rule 3 (atomic_rmw_body ib (and (mie2_enabled) (ty_32_or_64 ty)) (littleendian)
                       (AtomicRmwOp.Nand) tmp val src)
      (push_alu_reg ib (aluop_not_and ty) tmp val (bswap_reg ty src)))
(rule 2 (atomic_rmw_body ib (and (mie2_disabled) (ty_32_or_64 ty)) (bigendian)
                       (AtomicRmwOp.Nand) tmp val src)
      (push_not_reg ib ty tmp
        (push_alu_reg ib (aluop_and ty) tmp val src)))
(rule 1 (atomic_rmw_body ib (and (mie2_disabled) (ty_32_or_64 ty)) (littleendian)
                       (AtomicRmwOp.Nand) tmp val src)
      (push_not_reg ib ty tmp
        (push_alu_reg ib (aluop_and ty) tmp val (bswap_reg ty src))))

;; Loop bodies for 8-/16-bit atomic bit operations.
;; These use the "rotate-then-<op>-selected bits" family of instructions.
;; For the Nand operation, we again perform And and invert the result.
(rule (atomic_rmw_body ib (ty_8_or_16 ty) flags (AtomicRmwOp.Xchg) tmp val src)
      (atomic_rmw_body_rxsbg ib ty flags (RxSBGOp.Insert) tmp val src))
(rule (atomic_rmw_body ib (ty_8_or_16 ty) flags (AtomicRmwOp.And) tmp val src)
      (atomic_rmw_body_rxsbg ib ty flags (RxSBGOp.And) tmp val src))
(rule (atomic_rmw_body ib (ty_8_or_16 ty) flags (AtomicRmwOp.Or) tmp val src)
      (atomic_rmw_body_rxsbg ib ty flags (RxSBGOp.Or) tmp val src))
(rule (atomic_rmw_body ib (ty_8_or_16 ty) flags (AtomicRmwOp.Xor) tmp val src)
      (atomic_rmw_body_rxsbg ib ty flags (RxSBGOp.Xor) tmp val src))
(rule (atomic_rmw_body ib (ty_8_or_16 ty) flags (AtomicRmwOp.Nand) tmp val src)
      (atomic_rmw_body_invert ib ty flags tmp
        (atomic_rmw_body_rxsbg ib ty flags (RxSBGOp.And) tmp val src)))

;; RxSBG subword operation.
(decl atomic_rmw_body_rxsbg (VecMInstBuilder Type MemFlags RxSBGOp
                             WritableReg Reg Reg) Reg)
;; 8-bit case: use the low byte of "src" and the high byte of "val".
(rule (atomic_rmw_body_rxsbg ib $I8 _ op tmp val src)
      (push_rxsbg ib op tmp val src 32 40 24))
;; 16-bit big-endian case: use the low two bytes of "src" and the
;; high two bytes of "val".
(rule 1 (atomic_rmw_body_rxsbg ib $I16 (bigendian) op tmp val src)
      (push_rxsbg ib op tmp val src 32 48 16))
;; 16-bit little-endian case: use the low two bytes of "src", byte-swapped
;; so they end up in the high two bytes, and the low two bytes of "val".
(rule (atomic_rmw_body_rxsbg ib $I16 (littleendian) op tmp val src)
      (push_rxsbg ib op tmp val (bswap_reg $I32 src) 48 64 -16))

;; Invert a subword.
(decl atomic_rmw_body_invert (VecMInstBuilder Type MemFlags WritableReg Reg) Reg)
;; 8-bit case: invert the high byte.
(rule (atomic_rmw_body_invert ib $I8 _ tmp val)
      (push_xor_uimm32shifted ib $I32 tmp val (uimm32shifted 0xff000000 0)))
;; 16-bit big-endian case: invert the two high bytes.
(rule 1 (atomic_rmw_body_invert ib $I16 (bigendian) tmp val)
      (push_xor_uimm32shifted ib $I32 tmp val (uimm32shifted 0xffff0000 0)))
;; 16-bit little-endian case: invert the two low bytes.
(rule (atomic_rmw_body_invert ib $I16 (littleendian) tmp val)
      (push_xor_uimm32shifted ib $I32 tmp val (uimm32shifted 0xffff 0)))

;; Loop bodies for atomic ADD/SUB operations.
(rule (atomic_rmw_body ib ty flags (AtomicRmwOp.Add) tmp val src)
      (atomic_rmw_body_addsub ib ty flags (aluop_add (ty_ext32 ty)) tmp val src))
(rule (atomic_rmw_body ib ty flags (AtomicRmwOp.Sub) tmp val src)
      (atomic_rmw_body_addsub ib ty flags (aluop_sub (ty_ext32 ty)) tmp val src))

;; Addition or subtraction operation.
(decl atomic_rmw_body_addsub (VecMInstBuilder Type MemFlags ALUOp
                              WritableReg Reg Reg) Reg)
;; 32/64-bit big-endian case: just a regular add/sub operation.
(rule 2 (atomic_rmw_body_addsub ib (ty_32_or_64 ty) (bigendian) op tmp val src)
      (push_alu_reg ib op tmp val src))
;; 32/64-bit little-endian case: byte-swap the value loaded from memory before
;; and after performing the operation in native endianness.
(rule 1 (atomic_rmw_body_addsub ib (ty_32_or_64 ty) (littleendian) op tmp val src)
      (let ((val_swapped Reg (push_bswap_reg ib ty tmp val))
            (res_swapped Reg (push_alu_reg ib op tmp val_swapped src)))
        (push_bswap_reg ib ty tmp res_swapped)))
;; 8-bit case: perform a 32-bit addition of the source value shifted by 24 bits
;; to the memory value, which contains the target in its high byte.
(rule (atomic_rmw_body_addsub ib $I8 _ op tmp val src)
      (let ((src_shifted Reg (lshl_imm $I32 src 24)))
        (push_alu_reg ib op tmp val src_shifted)))
;; 16-bit big-endian case: similar, just shift the source by 16 bits.
(rule 3 (atomic_rmw_body_addsub ib $I16 (bigendian) op tmp val src)
      (let ((src_shifted Reg (lshl_imm $I32 src 16)))
        (push_alu_reg ib op tmp val src_shifted)))
;; 16-bit little-endian case: the same, but in addition we need to byte-swap
;; the memory value before and after the operation.  Since the value was placed
;; in the low two bytes by our standard rotation, we can use a 32-bit byte-swap
;; and the native-endian value will end up in the high bytes where we need it
;; to perform the operation.
(rule (atomic_rmw_body_addsub ib $I16 (littleendian) op tmp val src)
      (let ((src_shifted Reg (lshl_imm $I32 src 16))
            (val_swapped Reg (push_bswap_reg ib $I32 tmp val))
            (res_swapped Reg (push_alu_reg ib op tmp val_swapped src_shifted)))
        (push_bswap_reg ib $I32 tmp res_swapped)))

;; Loop bodies for atomic MIN/MAX operations.
(rule (atomic_rmw_body ib ty flags (AtomicRmwOp.Smin) tmp val src)
      (atomic_rmw_body_minmax ib ty flags (cmpop_cmps (ty_ext32 ty))
        (intcc_as_cond (IntCC.SignedLessThan)) tmp val src))
(rule (atomic_rmw_body ib ty flags (AtomicRmwOp.Smax) tmp val src)
      (atomic_rmw_body_minmax ib ty flags (cmpop_cmps (ty_ext32 ty))
        (intcc_as_cond (IntCC.SignedGreaterThan)) tmp val src))
(rule (atomic_rmw_body ib ty flags (AtomicRmwOp.Umin) tmp val src)
      (atomic_rmw_body_minmax ib ty flags (cmpop_cmpu (ty_ext32 ty))
        (intcc_as_cond (IntCC.UnsignedLessThan)) tmp val src))
(rule (atomic_rmw_body ib ty flags (AtomicRmwOp.Umax) tmp val src)
      (atomic_rmw_body_minmax ib ty flags (cmpop_cmpu (ty_ext32 ty))
        (intcc_as_cond (IntCC.UnsignedGreaterThan)) tmp val src))

;; Minimum or maximum operation.
(decl atomic_rmw_body_minmax (VecMInstBuilder Type MemFlags CmpOp Cond
                              WritableReg Reg Reg) Reg)
;; 32/64-bit big-endian case: just a comparison followed by a conditional
;; break out of the loop if the memory value does not need to change.
;; If it does need to change, the new value is simply the source operand.
(rule 2 (atomic_rmw_body_minmax ib (ty_32_or_64 ty) (bigendian)
                              op cond tmp val src)
      (let ((_ Reg (push_break_if ib (cmp_rr op src val) (invert_cond cond))))
        src))
;; 32/64-bit little-endian case: similar, but we need to byte-swap the
;; memory value before the comparison.  If we need to store the new value,
;; it also needs to be byte-swapped.
(rule 1 (atomic_rmw_body_minmax ib (ty_32_or_64 ty) (littleendian)
                              op cond tmp val src)
      (let ((val_swapped Reg (push_bswap_reg ib ty tmp val))
            (_ Reg (push_break_if ib (cmp_rr op src val_swapped)
                                     (invert_cond cond))))
        (push_bswap_reg ib ty tmp src)))
;; 8-bit case: compare the memory value (which contains the target in the
;; high byte) with the source operand shifted by 24 bits.  Note that in
;; the case where the high bytes are equal, the comparison may succeed
;; or fail depending on the unrelated low bits of the memory value, and
;; so we either may or may not perform the update.  But it would be an
;; update with the same value in any case, so this does not matter.
(rule (atomic_rmw_body_minmax ib $I8 _ op cond tmp val src)
      (let ((src_shifted Reg (lshl_imm $I32 src 24))
            (_ Reg (push_break_if ib (cmp_rr op src_shifted val)
                                     (invert_cond cond))))
        (push_rxsbg ib (RxSBGOp.Insert) tmp val src_shifted 32 40 0)))
;; 16-bit big-endian case: similar, just shift the source by 16 bits.
(rule 3 (atomic_rmw_body_minmax ib $I16 (bigendian) op cond tmp val src)
      (let ((src_shifted Reg (lshl_imm $I32 src 16))
            (_ Reg (push_break_if ib (cmp_rr op src_shifted val)
                                     (invert_cond cond))))
        (push_rxsbg ib (RxSBGOp.Insert) tmp val src_shifted 32 48 0)))
;; 16-bit little-endian case: similar, but in addition byte-swap the
;; memory value before and after the operation, like for _addsub_.
(rule (atomic_rmw_body_minmax ib $I16 (littleendian) op cond tmp val src)
      (let ((src_shifted Reg (lshl_imm $I32 src 16))
            (val_swapped Reg (push_bswap_reg ib $I32 tmp val))
            (_ Reg (push_break_if ib (cmp_rr op src_shifted val_swapped)
                                     (invert_cond cond)))
            (res_swapped Reg (push_rxsbg ib (RxSBGOp.Insert)
                                tmp val_swapped src_shifted 32 48 0)))
        (push_bswap_reg ib $I32 tmp res_swapped)))


;;;; Rules for `atomic_cas` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; 32/64-bit big-endian atomic compare-and-swap instruction.
(rule 2 (lower (has_type (ty_32_or_64 ty)
               (atomic_cas flags @ (bigendian) addr src1 src2)))
      (atomic_cas_impl ty (put_in_reg src1) (put_in_reg src2)
                       (lower_address flags addr (zero_offset))))

;; 32/64-bit little-endian atomic compare-and-swap instruction.
;; Implemented by byte-swapping old/new inputs and the output.
(rule 1 (lower (has_type (ty_32_or_64 ty)
               (atomic_cas flags @ (littleendian) addr src1 src2)))
      (bswap_reg ty (atomic_cas_impl ty (bswap_reg ty (put_in_reg src1))
                                     (bswap_reg ty (put_in_reg src2))
                                     (lower_address flags addr (zero_offset)))))

;; 8/16-bit atomic compare-and-swap implemented via loop.
(rule (lower (has_type (ty_8_or_16 ty) (atomic_cas flags addr src1 src2)))
      (let ((src1_reg Reg (put_in_reg src1))
            (src2_reg Reg (put_in_reg src2))
            (addr_reg Reg (put_in_reg addr))
            ;; Prepare access to the surrounding aligned word.
            (bitshift Reg (casloop_bitshift addr_reg))
            (aligned_addr Reg (casloop_aligned_addr addr_reg))
            ;; Create body of compare-and-swap loop.
            (ib VecMInstBuilder (inst_builder_new))
            (val0 Reg (writable_reg_to_reg (casloop_val_reg)))
            (val1 Reg (casloop_rotate_in ib ty flags bitshift val0))
            (val2 Reg (atomic_cas_body ib ty flags
                        (casloop_tmp_reg) val1 src1_reg src2_reg))
            (val3 Reg (casloop_rotate_out ib ty flags bitshift val2)))
        ;; Emit compare-and-swap loop and extract final result.
        (casloop_subword ib ty flags aligned_addr bitshift val3)))

;; Emit loop body instructions to perform a subword compare-and-swap.
(decl atomic_cas_body (VecMInstBuilder Type MemFlags
                       WritableReg Reg Reg Reg) Reg)

;; 8-bit case: "val" contains the value loaded from memory in the high byte.
;; Compare with the comparison value in the low byte of "src1".  If unequal,
;; break out of the loop, otherwise replace the target byte in "val" with
;; the low byte of "src2".
(rule (atomic_cas_body ib $I8 _ tmp val src1 src2)
      (let ((_ Reg (push_break_if ib (rxsbg_test (RxSBGOp.Xor) val src1 32 40 24)
                                     (intcc_as_cond (IntCC.NotEqual)))))
        (push_rxsbg ib (RxSBGOp.Insert) tmp val src2 32 40 24)))

;; 16-bit big-endian case: Same as above, except with values in the high
;; two bytes of "val" and low two bytes of "src1" and "src2".
(rule 1 (atomic_cas_body ib $I16 (bigendian) tmp val src1 src2)
      (let ((_ Reg (push_break_if ib (rxsbg_test (RxSBGOp.Xor) val src1 32 48 16)
                                     (intcc_as_cond (IntCC.NotEqual)))))
        (push_rxsbg ib (RxSBGOp.Insert) tmp val src2 32 48 16)))

;; 16-bit little-endian case: "val" here contains a little-endian value in the
;; *low* two bytes.  "src1" and "src2" contain native (i.e. big-endian) values
;; in their low two bytes.  Perform the operation in little-endian mode by
;; byte-swapping "src1" and "src" ahead of the loop.  Note that this is a
;; 32-bit operation so the little-endian 16-bit values end up in the *high*
;; two bytes of the swapped values.
(rule (atomic_cas_body ib $I16 (littleendian) tmp val src1 src2)
      (let ((src1_swapped Reg (bswap_reg $I32 src1))
            (src2_swapped Reg (bswap_reg $I32 src2))
            (_ Reg (push_break_if ib
                     (rxsbg_test (RxSBGOp.Xor) val src1_swapped 48 64 -16)
                     (intcc_as_cond (IntCC.NotEqual)))))
        (push_rxsbg ib (RxSBGOp.Insert) tmp val src2_swapped 48 64 -16)))


;;;; Rules for `atomic_load` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Atomic loads can be implemented via regular loads on this platform.

;; 8-bit atomic load.
(rule (lower (has_type $I8 (atomic_load flags addr)))
      (zext32_mem $I8 (lower_address flags addr (zero_offset))))

;; 16-bit big-endian atomic load.
(rule 1 (lower (has_type $I16 (atomic_load flags @ (bigendian) addr)))
      (zext32_mem $I16 (lower_address flags addr (zero_offset))))

;; 16-bit little-endian atomic load.
(rule (lower (has_type $I16 (atomic_load flags @ (littleendian) addr)))
      (loadrev16 (lower_address flags addr (zero_offset))))

;; 32-bit big-endian atomic load.
(rule 1 (lower (has_type $I32 (atomic_load flags @ (bigendian) addr)))
      (load32 (lower_address flags addr (zero_offset))))

;; 32-bit little-endian atomic load.
(rule (lower (has_type $I32 (atomic_load flags @ (littleendian) addr)))
      (loadrev32 (lower_address flags addr (zero_offset))))

;; 64-bit big-endian atomic load.
(rule 1 (lower (has_type $I64 (atomic_load flags @ (bigendian) addr)))
      (load64 (lower_address flags addr (zero_offset))))

;; 64-bit little-endian atomic load.
(rule (lower (has_type $I64 (atomic_load flags @ (littleendian) addr)))
      (loadrev64 (lower_address flags addr (zero_offset))))


;;;; Rules for `atomic_store` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Atomic stores can be implemented via regular stores followed by a fence.
(decl atomic_store_impl (SideEffectNoResult) InstOutput)
(rule (atomic_store_impl store)
      (let ((_ InstOutput (side_effect store)))
         (side_effect (fence_impl))))

;; 8-bit atomic store.
(rule (lower (atomic_store flags val @ (value_type $I8) addr))
      (atomic_store_impl (istore8_impl flags val addr (zero_offset))))

;; 16-bit atomic store.
(rule (lower (atomic_store flags val @ (value_type $I16) addr))
      (atomic_store_impl (istore16_impl flags val addr (zero_offset))))

;; 32-bit atomic store.
(rule (lower (atomic_store flags val @ (value_type $I32) addr))
      (atomic_store_impl (istore32_impl flags val addr (zero_offset))))

;; 64-bit atomic store.
(rule (lower (atomic_store flags val @ (value_type $I64) addr))
      (atomic_store_impl (istore64_impl flags val addr (zero_offset))))


;;;; Rules for `fence` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Fence to ensure sequential consistency.
(rule (lower (fence))
      (side_effect (fence_impl)))


;;;; Rules for `icmp` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; We want to optimize the typical use of `icmp` (generating an integer 0/1
;; result) followed by some user, like a `select` or a conditional branch.
;; Instead of first generating the integer result and later testing it again,
;; we want to sink the comparison to be performed at the site of use.
;;
;; To enable this, we provide generic helpers that return a `ProducesBool`
;; encapsulating the comparison in question, which can be used by all the
;; above scenarios.
;;
;; N.B. There are specific considerations when sinking a memory load into a
;; comparison.  When emitting an `icmp` directly, this can of course be done
;; as usual.  However, when we use the `ProducesBool` elsewhere, we need to
;; consider *three* instructions: the load, the `icmp`, and the final user
;; (e.g. a conditional branch).  The only way to safely sink the load would
;; be to sink it direct into the final user, which is only possible if there
;; is no *other* user of the `icmp` result.  This is not currently being
;; verified by the `SinkableInst` logic, so to be safe we do not perform this
;; optimization at all.
;;
;; The generic `icmp_val` helper therefore has a flag indicating whether
;; it is being invoked in a context where it is safe to sink memory loads
;; (e.g. when directly emitting an `icmp`), or whether it is not (e.g. when
;; sinking the `icmp` result into a conditional branch or select).

;; Main `icmp` entry point.  Generate a `ProducesBool` capturing the
;; integer comparison and immediately lower it to a 0/1 integer result.
;; In this case, it is safe to sink memory loads.
(rule -1 (lower (has_type (fits_in_64 ty) (icmp int_cc x y)))
      (lower_bool ty (icmp_val true int_cc x y)))


;; Return a `ProducesBool` to implement any integer comparison.
;; The first argument is a flag to indicate whether it is safe to sink
;; memory loads as discussed above.
(decl icmp_val (bool IntCC Value Value) ProducesBool)

;; Dispatch for signed comparisons.
(rule -1 (icmp_val allow_mem int_cc @ (signed) x @ (value_type (fits_in_64 _)) y)
      (bool (icmps_val allow_mem x y) (intcc_as_cond int_cc)))
;; Dispatch for unsigned comparisons.
(rule -2 (icmp_val allow_mem int_cc @ (unsigned) x @ (value_type (fits_in_64 _)) y)
      (bool (icmpu_val allow_mem x y) (intcc_as_cond int_cc)))


;; Return a `ProducesBool` to implement signed integer comparisons.
(decl icmps_val (bool Value Value) ProducesFlags)

;; Compare (signed) two registers.
(rule 0 (icmps_val _ x @ (value_type (fits_in_64 ty)) y)
      (icmps_reg (ty_ext32 ty) (put_in_reg_sext32 x) (put_in_reg_sext32 y)))

;; Compare (signed) a register and a sign-extended register.
(rule 3 (icmps_val _ x @ (value_type (fits_in_64 ty)) (sext32_value y))
      (icmps_reg_sext32 ty x y))

;; Compare (signed) a register and an immediate.
(rule 2 (icmps_val _ x @ (value_type (fits_in_64 ty)) (i16_from_value y))
      (icmps_simm16 (ty_ext32 ty) (put_in_reg_sext32 x) y))
(rule 1 (icmps_val _ x @ (value_type (fits_in_64 ty)) (i32_from_value y))
      (icmps_simm32 (ty_ext32 ty) (put_in_reg_sext32 x) y))

;; Compare (signed) a register and memory (32/64-bit types).
(rule 4 (icmps_val true x @ (value_type (fits_in_64 ty)) (sinkable_load_32_64 y))
      (icmps_mem ty x (sink_load y)))

;; Compare (signed) a register and memory (16-bit types).
(rule 5 (icmps_val true x @ (value_type (fits_in_64 ty)) (sinkable_load_16 y))
      (icmps_mem_sext16 (ty_ext32 ty) (put_in_reg_sext32 x) (sink_load y)))

;; Compare (signed) a register and sign-extended memory.
(rule 4 (icmps_val true x @ (value_type (fits_in_64 ty)) (sinkable_sload16 y))
      (icmps_mem_sext16 ty x (sink_sload16 y)))
(rule 4 (icmps_val true x @ (value_type (fits_in_64 ty)) (sinkable_sload32 y))
      (icmps_mem_sext32 ty x (sink_sload32 y)))


;; Return a `ProducesBool` to implement unsigned integer comparisons.
(decl icmpu_val (bool Value Value) ProducesFlags)

;; Compare (unsigned) two registers.
(rule (icmpu_val _ x @ (value_type (fits_in_64 ty)) y)
      (icmpu_reg (ty_ext32 ty) (put_in_reg_zext32 x) (put_in_reg_zext32 y)))

;; Compare (unsigned) a register and a sign-extended register.
(rule 1 (icmpu_val _ x @ (value_type (fits_in_64 ty)) (zext32_value y))
      (icmpu_reg_zext32 ty x y))

;; Compare (unsigned) a register and an immediate.
(rule 2 (icmpu_val _ x @ (value_type (fits_in_64 ty)) (u32_from_value y))
      (icmpu_uimm32 (ty_ext32 ty) (put_in_reg_zext32 x) y))

;; Compare (unsigned) a register and memory (32/64-bit types).
(rule 4 (icmpu_val true x @ (value_type (fits_in_64 ty)) (sinkable_load_32_64 y))
      (icmpu_mem ty x (sink_load y)))

;; Compare (unsigned) a register and memory (16-bit types).
;; Note that the ISA only provides instructions with a PC-relative memory
;; address here, so we need to check whether the sinkable load matches this.
(rule 3 (icmpu_val true x @ (value_type (fits_in_64 ty))
                 (sinkable_load_16 ld))
      (if-let y (load_sym ld))
      (icmpu_mem_zext16 (ty_ext32 ty) (put_in_reg_zext32 x) (sink_load y)))

;; Compare (unsigned) a register and zero-extended memory.
;; Note that the ISA only provides instructions with a PC-relative memory
;; address here, so we need to check whether the sinkable load matches this.
(rule 3 (icmpu_val true x @ (value_type (fits_in_64 ty))
                 (sinkable_uload16 ld))
      (if-let y (uload16_sym ld))
      (icmpu_mem_zext16 ty x (sink_uload16 y)))
(rule 3 (icmpu_val true x @ (value_type (fits_in_64 ty)) (sinkable_uload32 y))
      (icmpu_mem_zext32 ty x (sink_uload32 y)))


;; Compare 128-bit integers for equality.
;; Implemented via element-wise comparison using the all-element true CC flag.
(rule (icmp_val _ (IntCC.Equal) x @ (value_type (vr128_ty _)) y)
      (bool (vec_cmpeqs $I64X2 x y)
            (floatcc_as_cond (FloatCC.Equal))))
(rule (icmp_val _ (IntCC.NotEqual) x @ (value_type (vr128_ty _)) y)
      (bool (vec_cmpeqs $I64X2 x y)
            (floatcc_as_cond (FloatCC.NotEqual))))

;; Compare (signed) 128-bit integers for relational inequality.
;; Implemented via synthetic instruction using VECG and VCHLGS.
(rule (icmp_val _ (IntCC.SignedGreaterThan) x @ (value_type (vr128_ty ty)) y)
      (vec_int128_scmphi x y))
(rule (icmp_val _ (IntCC.SignedLessThan) x @ (value_type (vr128_ty ty)) y)
      (vec_int128_scmphi y x))
(rule (icmp_val _ (IntCC.SignedGreaterThanOrEqual) x @ (value_type (vr128_ty ty)) y)
      (invert_bool (vec_int128_scmphi y x)))
(rule (icmp_val _ (IntCC.SignedLessThanOrEqual) x @ (value_type (vr128_ty ty)) y)
      (invert_bool (vec_int128_scmphi x y)))

;; Compare (unsigned) 128-bit integers for relational inequality.
;; Implemented via synthetic instruction using VECLG and VCHLGS.
(rule (icmp_val _ (IntCC.UnsignedGreaterThan) x @ (value_type (vr128_ty ty)) y)
      (vec_int128_ucmphi x y))
(rule (icmp_val _ (IntCC.UnsignedLessThan) x @ (value_type (vr128_ty ty)) y)
      (vec_int128_ucmphi y x))
(rule (icmp_val _ (IntCC.UnsignedGreaterThanOrEqual) x @ (value_type (vr128_ty ty)) y)
      (invert_bool (vec_int128_ucmphi y x)))
(rule (icmp_val _ (IntCC.UnsignedLessThanOrEqual) x @ (value_type (vr128_ty ty)) y)
      (invert_bool (vec_int128_ucmphi x y)))


;; Vector `icmp` produces a boolean vector.
;; We need to handle the various IntCC flags separately here.

(rule (lower (has_type (ty_vec128 ty) (icmp (IntCC.Equal) x y)))
      (vec_cmpeq ty x y))
(rule (lower (has_type (ty_vec128 ty) (icmp (IntCC.NotEqual) x y)))
      (vec_not ty (vec_cmpeq ty x y)))
(rule (lower (has_type (ty_vec128 ty) (icmp (IntCC.SignedGreaterThan) x y)))
      (vec_cmph ty x y))
(rule (lower (has_type (ty_vec128 ty) (icmp (IntCC.SignedLessThanOrEqual) x y)))
      (vec_not ty (vec_cmph ty x y)))
(rule (lower (has_type (ty_vec128 ty) (icmp (IntCC.SignedLessThan) x y)))
      (vec_cmph ty y x))
(rule (lower (has_type (ty_vec128 ty) (icmp (IntCC.SignedGreaterThanOrEqual) x y)))
      (vec_not ty (vec_cmph ty y x)))
(rule (lower (has_type (ty_vec128 ty) (icmp (IntCC.UnsignedGreaterThan) x y)))
      (vec_cmphl ty x y))
(rule (lower (has_type (ty_vec128 ty) (icmp (IntCC.UnsignedLessThanOrEqual) x y)))
      (vec_not ty (vec_cmphl ty x y)))
(rule (lower (has_type (ty_vec128 ty) (icmp (IntCC.UnsignedLessThan) x y)))
      (vec_cmphl ty y x))
(rule (lower (has_type (ty_vec128 ty) (icmp (IntCC.UnsignedGreaterThanOrEqual) x y)))
      (vec_not ty (vec_cmphl ty y x)))


;;;; Rules for `fcmp` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Main `fcmp` entry point.  Generate a `ProducesBool` capturing the
;; integer comparison and immediately lower it to a 0/1 integer result.
(rule -1 (lower (has_type (fits_in_64 ty) (fcmp float_cc x y)))
      (lower_bool ty (fcmp_val float_cc x y)))

;; Return a `ProducesBool` to implement any floating-point comparison.
(decl fcmp_val (FloatCC Value Value) ProducesBool)
(rule (fcmp_val float_cc x @ (value_type ty) y)
      (bool (fcmp_reg ty x y)
            (floatcc_as_cond float_cc)))

;; Vector `fcmp` produces a boolean vector.
;; We need to handle the various FloatCC flags separately here.

(rule (lower (has_type (ty_vec128 ty) (fcmp (FloatCC.Equal) x y)))
      (vec_fcmpeq ty x y))
(rule (lower (has_type (ty_vec128 ty) (fcmp (FloatCC.NotEqual) x y)))
      (vec_not ty (vec_fcmpeq ty x y)))
(rule (lower (has_type (ty_vec128 ty) (fcmp (FloatCC.GreaterThan) x y)))
      (vec_fcmph ty x y))
(rule (lower (has_type (ty_vec128 ty) (fcmp (FloatCC.UnorderedOrLessThanOrEqual) x y)))
      (vec_not ty (vec_fcmph ty x y)))
(rule (lower (has_type (ty_vec128 ty) (fcmp (FloatCC.GreaterThanOrEqual) x y)))
      (vec_fcmphe ty x y))
(rule (lower (has_type (ty_vec128 ty) (fcmp (FloatCC.UnorderedOrLessThan) x y)))
      (vec_not ty (vec_fcmphe ty x y)))
(rule (lower (has_type (ty_vec128 ty) (fcmp (FloatCC.LessThan) x y)))
      (vec_fcmph ty y x))
(rule (lower (has_type (ty_vec128 ty) (fcmp (FloatCC.UnorderedOrGreaterThanOrEqual) x y)))
      (vec_not ty (vec_fcmph ty y x)))
(rule (lower (has_type (ty_vec128 ty) (fcmp (FloatCC.LessThanOrEqual) x y)))
      (vec_fcmphe ty y x))
(rule (lower (has_type (ty_vec128 ty) (fcmp (FloatCC.UnorderedOrGreaterThan) x y)))
      (vec_not ty (vec_fcmphe ty y x)))
(rule (lower (has_type (ty_vec128 ty) (fcmp (FloatCC.Ordered) x y)))
      (vec_or ty (vec_fcmphe ty x y) (vec_fcmphe ty y x)))
(rule (lower (has_type (ty_vec128 ty) (fcmp (FloatCC.Unordered) x y)))
      (vec_not_or ty (vec_fcmphe ty x y) (vec_fcmphe ty y x)))
(rule (lower (has_type (ty_vec128 ty) (fcmp (FloatCC.OrderedNotEqual) x y)))
      (vec_or ty (vec_fcmph ty x y) (vec_fcmph ty y x)))
(rule (lower (has_type (ty_vec128 ty) (fcmp (FloatCC.UnorderedOrEqual) x y)))
      (vec_not_or ty (vec_fcmph ty x y) (vec_fcmph ty y x)))


;;;; Rules for `vall_true` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Main `vall_true` entry point.  Generate a `ProducesBool` capturing the
;; comparison and immediately lower it to a 0/1 integer result.
(rule (lower (has_type (fits_in_64 ty) (vall_true x)))
      (lower_bool ty (vall_true_val x)))

;; Return a `ProducesBool` to implement `vall_true`.
(decl vall_true_val (Value) ProducesBool)
(rule -1 (vall_true_val x @ (value_type ty))
      (bool (vec_cmpeqs ty x (vec_imm ty 0))
            (floatcc_as_cond (FloatCC.Unordered))))

;; Short-circuit `vall_true` on the result of a `icmp`.
(rule (vall_true_val (has_type ty (icmp (IntCC.Equal) x y)))
      (bool (vec_cmpeqs ty x y)
            (floatcc_as_cond (FloatCC.Equal))))
(rule (vall_true_val (has_type ty (icmp (IntCC.NotEqual) x y)))
      (bool (vec_cmpeqs ty x y)
            (floatcc_as_cond (FloatCC.Unordered))))
(rule (vall_true_val (has_type ty (icmp (IntCC.SignedGreaterThan) x y)))
      (bool (vec_cmphs ty x y)
            (floatcc_as_cond (FloatCC.Equal))))
(rule (vall_true_val (has_type ty (icmp (IntCC.SignedLessThanOrEqual) x y)))
      (bool (vec_cmphs ty x y)
            (floatcc_as_cond (FloatCC.Unordered))))
(rule (vall_true_val (has_type ty (icmp (IntCC.SignedLessThan) x y)))
      (bool (vec_cmphs ty y x)
            (floatcc_as_cond (FloatCC.Equal))))
(rule (vall_true_val (has_type ty (icmp (IntCC.SignedGreaterThanOrEqual) x y)))
      (bool (vec_cmphs ty y x)
            (floatcc_as_cond (FloatCC.Unordered))))
(rule (vall_true_val (has_type ty (icmp (IntCC.UnsignedGreaterThan) x y)))
      (bool (vec_cmphls ty x y)
            (floatcc_as_cond (FloatCC.Equal))))
(rule (vall_true_val (has_type ty (icmp (IntCC.UnsignedLessThanOrEqual) x y)))
      (bool (vec_cmphls ty x y)
            (floatcc_as_cond (FloatCC.Unordered))))
(rule (vall_true_val (has_type ty (icmp (IntCC.UnsignedLessThan) x y)))
      (bool (vec_cmphls ty y x)
            (floatcc_as_cond (FloatCC.Equal))))
(rule (vall_true_val (has_type ty (icmp (IntCC.UnsignedGreaterThanOrEqual) x y)))
      (bool (vec_cmphls ty y x)
            (floatcc_as_cond (FloatCC.Unordered))))

;; Short-circuit `vall_true` on the result of a `fcmp` where possible.
(rule (vall_true_val (has_type ty (fcmp (FloatCC.Equal) x y)))
      (bool (vec_fcmpeqs ty x y)
            (floatcc_as_cond (FloatCC.Equal))))
(rule (vall_true_val (has_type ty (fcmp (FloatCC.NotEqual) x y)))
      (bool (vec_fcmpeqs ty x y)
            (floatcc_as_cond (FloatCC.Unordered))))
(rule (vall_true_val (has_type ty (fcmp (FloatCC.GreaterThan) x y)))
      (bool (vec_fcmphs ty x y)
            (floatcc_as_cond (FloatCC.Equal))))
(rule (vall_true_val (has_type ty (fcmp (FloatCC.UnorderedOrLessThanOrEqual) x y)))
      (bool (vec_fcmphs ty x y)
            (floatcc_as_cond (FloatCC.Unordered))))
(rule (vall_true_val (has_type ty (fcmp (FloatCC.GreaterThanOrEqual) x y)))
      (bool (vec_fcmphes ty x y)
            (floatcc_as_cond (FloatCC.Equal))))
(rule (vall_true_val (has_type ty (fcmp (FloatCC.UnorderedOrLessThan) x y)))
      (bool (vec_fcmphes ty x y)
            (floatcc_as_cond (FloatCC.Unordered))))
(rule (vall_true_val (has_type ty (fcmp (FloatCC.LessThan) x y)))
      (bool (vec_fcmphs ty y x)
            (floatcc_as_cond (FloatCC.Equal))))
(rule (vall_true_val (has_type ty (fcmp (FloatCC.UnorderedOrGreaterThanOrEqual) x y)))
      (bool (vec_fcmphs ty y x)
            (floatcc_as_cond (FloatCC.Unordered))))
(rule (vall_true_val (has_type ty (fcmp (FloatCC.LessThanOrEqual) x y)))
      (bool (vec_fcmphes ty y x)
            (floatcc_as_cond (FloatCC.Equal))))
(rule (vall_true_val (has_type ty (fcmp (FloatCC.UnorderedOrGreaterThan) x y)))
      (bool (vec_fcmphes ty y x)
            (floatcc_as_cond (FloatCC.Unordered))))


;;;; Rules for `vany_true` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Main `vany_true` entry point.  Generate a `ProducesBool` capturing the
;; comparison and immediately lower it to a 0/1 integer result.
(rule (lower (has_type (fits_in_64 ty) (vany_true x)))
      (lower_bool ty (vany_true_val x)))

;; Return a `ProducesBool` to implement `vany_true`.
(decl vany_true_val (Value) ProducesBool)
(rule -1 (vany_true_val x @ (value_type ty))
      (bool (vec_cmpeqs ty x (vec_imm ty 0))
            (floatcc_as_cond (FloatCC.NotEqual))))

;; Short-circuit `vany_true` on the result of a `icmp`.
(rule (vany_true_val (has_type ty (icmp (IntCC.Equal) x y)))
      (bool (vec_cmpeqs ty x y)
            (floatcc_as_cond (FloatCC.Ordered))))
(rule (vany_true_val (has_type ty (icmp (IntCC.NotEqual) x y)))
      (bool (vec_cmpeqs ty x y)
            (floatcc_as_cond (FloatCC.NotEqual))))
(rule (vany_true_val (has_type ty (icmp (IntCC.SignedGreaterThan) x y)))
      (bool (vec_cmphs ty x y)
            (floatcc_as_cond (FloatCC.Ordered))))
(rule (vany_true_val (has_type ty (icmp (IntCC.SignedLessThanOrEqual) x y)))
      (bool (vec_cmphs ty x y)
            (floatcc_as_cond (FloatCC.NotEqual))))
(rule (vany_true_val (has_type ty (icmp (IntCC.SignedLessThan) x y)))
      (bool (vec_cmphs ty y x)
            (floatcc_as_cond (FloatCC.Ordered))))
(rule (vany_true_val (has_type ty (icmp (IntCC.SignedGreaterThanOrEqual) x y)))
      (bool (vec_cmphs ty y x)
            (floatcc_as_cond (FloatCC.NotEqual))))
(rule (vany_true_val (has_type ty (icmp (IntCC.UnsignedGreaterThan) x y)))
      (bool (vec_cmphls ty x y)
            (floatcc_as_cond (FloatCC.Ordered))))
(rule (vany_true_val (has_type ty (icmp (IntCC.UnsignedLessThanOrEqual) x y)))
      (bool (vec_cmphls ty x y)
            (floatcc_as_cond (FloatCC.NotEqual))))
(rule (vany_true_val (has_type ty (icmp (IntCC.UnsignedLessThan) x y)))
      (bool (vec_cmphls ty y x)
            (floatcc_as_cond (FloatCC.Ordered))))
(rule (vany_true_val (has_type ty (icmp (IntCC.UnsignedGreaterThanOrEqual) x y)))
      (bool (vec_cmphls ty y x)
            (floatcc_as_cond (FloatCC.NotEqual))))

;; Short-circuit `vany_true` on the result of a `fcmp` where possible.
(rule (vany_true_val (has_type ty (fcmp (FloatCC.Equal) x y)))
      (bool (vec_fcmpeqs ty x y)
            (floatcc_as_cond (FloatCC.Ordered))))
(rule (vany_true_val (has_type ty (fcmp (FloatCC.NotEqual) x y)))
      (bool (vec_fcmpeqs ty x y)
            (floatcc_as_cond (FloatCC.NotEqual))))
(rule (vany_true_val (has_type ty (fcmp (FloatCC.GreaterThan) x y)))
      (bool (vec_fcmphs ty x y)
            (floatcc_as_cond (FloatCC.Ordered))))
(rule (vany_true_val (has_type ty (fcmp (FloatCC.UnorderedOrLessThanOrEqual) x y)))
      (bool (vec_fcmphs ty x y)
            (floatcc_as_cond (FloatCC.NotEqual))))
(rule (vany_true_val (has_type ty (fcmp (FloatCC.GreaterThanOrEqual) x y)))
      (bool (vec_fcmphes ty x y)
            (floatcc_as_cond (FloatCC.Ordered))))
(rule (vany_true_val (has_type ty (fcmp (FloatCC.UnorderedOrLessThan) x y)))
      (bool (vec_fcmphes ty x y)
            (floatcc_as_cond (FloatCC.NotEqual))))
(rule (vany_true_val (has_type ty (fcmp (FloatCC.LessThan) x y)))
      (bool (vec_fcmphs ty y x)
            (floatcc_as_cond (FloatCC.Ordered))))
(rule (vany_true_val (has_type ty (fcmp (FloatCC.UnorderedOrGreaterThanOrEqual) x y)))
      (bool (vec_fcmphs ty y x)
            (floatcc_as_cond (FloatCC.NotEqual))))
(rule (vany_true_val (has_type ty (fcmp (FloatCC.LessThanOrEqual) x y)))
      (bool (vec_fcmphes ty y x)
            (floatcc_as_cond (FloatCC.Ordered))))
(rule (vany_true_val (has_type ty (fcmp (FloatCC.UnorderedOrGreaterThan) x y)))
      (bool (vec_fcmphes ty y x)
            (floatcc_as_cond (FloatCC.NotEqual))))


;;;; Rules for `vhigh_bits` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(rule (lower (vhigh_bits x @ (value_type (multi_lane 8 16))))
      (if-let (LaneOrder.LittleEndian) (lane_order))
      (let ((mask Reg (vec_imm $I8X16 (imm8x16 0 8 16 24 32 40 48 56
                                               64 72 80 88 96 104 112 120))))
        (vec_extract_lane $I64X2 (vec_bitpermute x mask) 0 (zero_reg))))
(rule 1 (lower (vhigh_bits x @ (value_type (multi_lane 8 16))))
      (if-let (LaneOrder.BigEndian) (lane_order))
      (let ((mask Reg (vec_imm $I8X16 (imm8x16 120 112 104 96 88 80 72 64
                                               56 48 40 32 24 16 8 0))))
        (vec_extract_lane $I64X2 (vec_bitpermute x mask) 0 (zero_reg))))

(rule (lower (vhigh_bits x @ (value_type (multi_lane 16 8))))
      (if-let (LaneOrder.LittleEndian) (lane_order))
      (let ((mask Reg (vec_imm $I8X16 (imm8x16 128 128 128 128 128 128 128 128
                                               0 16 32 48 64 80 96 112))))
        (vec_extract_lane $I64X2 (vec_bitpermute x mask) 0 (zero_reg))))
(rule 1 (lower (vhigh_bits x @ (value_type (multi_lane 16 8))))
      (if-let (LaneOrder.BigEndian) (lane_order))
      (let ((mask Reg (vec_imm $I8X16 (imm8x16 128 128 128 128 128 128 128 128
                                               112 96 80 64 48 32 16 0))))
        (vec_extract_lane $I64X2 (vec_bitpermute x mask) 0 (zero_reg))))

(rule (lower (vhigh_bits x @ (value_type (multi_lane 32 4))))
      (if-let (LaneOrder.LittleEndian) (lane_order))
      (let ((mask Reg (vec_imm $I8X16 (imm8x16 128 128 128 128 128 128 128 128
                                               128 128 128 128 0 32 64 96))))
        (vec_extract_lane $I64X2 (vec_bitpermute x mask) 0 (zero_reg))))
(rule 1 (lower (vhigh_bits x @ (value_type (multi_lane 32 4))))
      (if-let (LaneOrder.BigEndian) (lane_order))
      (let ((mask Reg (vec_imm $I8X16 (imm8x16 128 128 128 128 128 128 128 128
                                               128 128 128 128 96 64 32 0))))
        (vec_extract_lane $I64X2 (vec_bitpermute x mask) 0 (zero_reg))))

(rule (lower (vhigh_bits x @ (value_type (multi_lane 64 2))))
      (if-let (LaneOrder.LittleEndian) (lane_order))
      (let ((mask Reg (vec_imm $I8X16 (imm8x16 128 128 128 128 128 128 128 128
                                               128 128 128 128 128 128 0 64))))
        (vec_extract_lane $I64X2 (vec_bitpermute x mask) 0 (zero_reg))))
(rule 1 (lower (vhigh_bits x @ (value_type (multi_lane 64 2))))
      (if-let (LaneOrder.BigEndian) (lane_order))
      (let ((mask Reg (vec_imm $I8X16 (imm8x16 128 128 128 128 128 128 128 128
                                               128 128 128 128 128 128 64 0))))
        (vec_extract_lane $I64X2 (vec_bitpermute x mask) 0 (zero_reg))))


;;;; Rules for `select` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Return a `ProducesBool` to capture the fact that the input value is nonzero.
;; In the common case where that input is the result of an `icmp` or `fcmp`
;; instruction, directly use that compare. Note that it is not safe to sink
;; memory loads here, see the `icmp` comment.
(decl value_nonzero (Value) ProducesBool)
(rule (value_nonzero (icmp int_cc x y)) (icmp_val false int_cc x y))
(rule (value_nonzero (fcmp float_cc x y)) (fcmp_val float_cc x y))
(rule -1 (value_nonzero val @ (value_type (gpr32_ty ty)))
      (bool (icmps_simm16 $I32 (put_in_reg_sext32 val) 0)
                          (intcc_as_cond (IntCC.NotEqual))))
(rule -2 (value_nonzero val @ (value_type (gpr64_ty ty)))
      (bool (icmps_simm16 $I64 (put_in_reg val) 0)
                          (intcc_as_cond (IntCC.NotEqual))))
(rule -3 (value_nonzero val @ (value_type (vr128_ty ty)))
      (bool (vec_cmpeqs $I64X2 val (vec_imm $I64X2 0))
            (floatcc_as_cond (FloatCC.NotEqual))))

;; Main `select` entry point.  Lower the `value_nonzero` result.
(rule (lower (has_type ty (select val_cond val_true val_false)))
      (select_bool_reg ty (value_nonzero val_cond)
                       (put_in_reg val_true) (put_in_reg val_false)))

;; Special-case some float-selection instructions for min/max
(rule 1 (lower (has_type (ty_scalar_float ty) (select (maybe_uextend (fcmp (FloatCC.LessThan) x y)) x y)))
        (fmin_pseudo_reg ty y x))
(rule 2 (lower (has_type (ty_scalar_float ty) (select (maybe_uextend (fcmp (FloatCC.LessThan) y x)) x y)))
        (fmax_pseudo_reg ty y x))


;;;; Rules for `select_spectre_guard` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; We need to guarantee a conditional move instruction.  But on this platform
;; this is already the best way to implement select in general, so the
;; implementation of `select_spectre_guard` is identical to `select`.
(rule (lower (has_type ty (select_spectre_guard
                             val_cond val_true val_false)))
      (select_bool_reg ty (value_nonzero val_cond)
                       (put_in_reg val_true) (put_in_reg val_false)))


;;;; Rules for `jump` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Unconditional branch.  The target is found as first (and only) element in
;; the list of the current block's branch targets passed as `targets`.
(rule (lower_branch (jump _) (single_target label))
      (emit_side_effect (jump_impl label)))


;;;; Rules for `br_table` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Jump table.  `targets` contains the default target followed by the
;; list of branch targets per index value.
(rule (lower_branch (br_table val_idx _) (jump_table_targets default targets))
      (let ((idx Reg (put_in_reg_zext64 val_idx))
            ;; Bounds-check the index and branch to default.
            ;; This is an internal branch that is not a terminator insn.
            ;; Instead, the default target is listed a potential target
            ;; in the final JTSequence, which is the block terminator.
            (cond ProducesBool
              (bool (icmpu_uimm32 $I64 idx (jump_table_size targets))
                    (intcc_as_cond (IntCC.UnsignedGreaterThanOrEqual))))
            (_ Unit (emit_side_effect (oneway_cond_br_bool cond default))))
        ;; Scale the index by the element size, and then emit the
        ;; compound instruction that does:
        ;;
        ;; larl %r1, <jt-base>
        ;; agf %r1, 0(%r1, %rScaledIndex)
        ;; br %r1
        ;; [jt entries]
        ;;
        ;; This must be *one* instruction in the vcode because
        ;; we cannot allow regalloc to insert any spills/fills
        ;; in the middle of the sequence; otherwise, the LARL's
        ;; PC-rel offset to the jumptable would be incorrect.
        ;; (The alternative is to introduce a relocation pass
        ;; for inlined jumptables, which is much worse, IMHO.)
        (emit_side_effect (jt_sequence (lshl_imm $I64 idx 2) targets))))


;;;; Rules for `brif` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Two-way conditional branch on nonzero.  `targets` contains:
;; - element 0: target if the condition is true (i.e. value is nonzero)
;; - element 1: target if the condition is false (i.e. value is zero)
(rule (lower_branch (brif val_cond _ _) (two_targets then else))
      (emit_side_effect (cond_br_bool (value_nonzero val_cond) then else)))


;;;; Rules for `trap` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(rule (lower (trap trap_code))
      (side_effect (trap_impl trap_code)))


;;;; Rules for `trapz` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(rule (lower (trapz val trap_code))
      (side_effect (trap_if_bool (invert_bool (value_nonzero val)) trap_code)))


;;;; Rules for `trapnz` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(rule (lower (trapnz val trap_code))
      (side_effect (trap_if_bool (value_nonzero val) trap_code)))


;;;; Rules for `debugtrap` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(rule (lower (debugtrap))
      (side_effect (debugtrap_impl)))

;;;; Rules for `uadd_overflow_trap` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; UaddOverflowTrap is implemented via a ADD LOGICAL instruction, which sets the
;; the condition code as follows:
;;   0   Result zero; no carry
;;   1   Result not zero; no carry
;;   2   Result zero; carry
;;   3   Result not zero; carry
;; This means "carry" corresponds to condition code 2 or 3, i.e.
;; a condition mask of 2 | 1.
;;
;; As this does not match any of the encodings used with a normal integer
;; comparison, this cannot be represented by any IntCC value.  We need to
;; remap the IntCC::UnsignedGreaterThan value that we have here as result
;; of the unsigned_add_overflow_condition call to the correct mask.

(rule 0 (lower (has_type (fits_in_64 ty) (uadd_overflow_trap x y tc)))
      (with_flags
        (add_logical_reg_with_flags_paired ty x y)
        (trap_if_impl (mask_as_cond 3) tc)))

;; Add a register an a zero-extended register.
(rule 4 (lower (has_type (fits_in_64 ty)
                         (uadd_overflow_trap x (zext32_value y) tc)))
      (with_flags
        (add_logical_reg_zext32_with_flags_paired ty x y)
        (trap_if_impl (mask_as_cond 3) tc)))
(rule 8 (lower (has_type (fits_in_64 ty)
                         (uadd_overflow_trap (zext32_value x) y tc)))
      (with_flags
        (add_logical_reg_zext32_with_flags_paired ty y x)
        (trap_if_impl (mask_as_cond 3) tc)))

;; Add a register and an immediate
(rule 3 (lower (has_type (fits_in_64 ty)
                         (uadd_overflow_trap x (u32_from_value y) tc)))
      (with_flags
        (add_logical_zimm32_with_flags_paired ty x y)
        (trap_if_impl (mask_as_cond 3) tc)))
(rule 7 (lower (has_type (fits_in_64 ty)
                         (uadd_overflow_trap (u32_from_value x) y tc)))
      (with_flags
        (add_logical_zimm32_with_flags_paired ty y x)
        (trap_if_impl (mask_as_cond 3) tc)))

;; Add a register and memory (32/64-bit types).
(rule 2 (lower (has_type (fits_in_64 ty)
                         (uadd_overflow_trap x (sinkable_load_32_64 y) tc)))
      (with_flags
        (add_logical_mem_with_flags_paired ty x (sink_load y))
        (trap_if_impl (mask_as_cond 3) tc)))
(rule 6 (lower (has_type (fits_in_64 ty)
                         (uadd_overflow_trap (sinkable_load_32_64 x) y tc)))
      (with_flags
        (add_logical_mem_with_flags_paired ty y (sink_load x))
        (trap_if_impl (mask_as_cond 3) tc)))

;; Add a register and zero-extended memory.
(rule 1 (lower (has_type (fits_in_64 ty)
                         (uadd_overflow_trap x (sinkable_uload32 y) tc)))
      (with_flags
        (add_logical_mem_zext32_with_flags_paired ty x (sink_uload32 y))
        (trap_if_impl (mask_as_cond 3) tc)))
(rule 5 (lower (has_type (fits_in_64 ty)
                         (uadd_overflow_trap (sinkable_uload32 x) y tc)))
      (with_flags
        (add_logical_mem_zext32_with_flags_paired ty y (sink_uload32 x))
        (trap_if_impl (mask_as_cond 3) tc)))

;;;; Rules for `return` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(rule (lower (return args))
      (lower_return args))


;;;; Rules for `call` and `call_indirect` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Direct call to an in-range function.
(rule 1 (lower (call (func_ref_data sig_ref name (reloc_distance_near)) args))
      (let ((abi Sig (abi_sig sig_ref))
            (uses CallArgList (lower_call_args abi (range 0 (abi_num_args abi)) args))
            (defs CallRetList (defs_init abi))
            (_ InstOutput (side_effect (abi_call abi name uses defs))))
        (lower_call_rets abi defs (range (abi_first_ret sig_ref abi)
                                         (abi_num_rets abi)) (output_builder_new))))

;; Direct call to an out-of-range function (implicitly via pointer).
(rule (lower (call (func_ref_data sig_ref name _) args))
      (let ((abi Sig (abi_sig sig_ref))
            (uses CallArgList (lower_call_args abi (range 0 (abi_num_args abi)) args))
            (defs CallRetList (defs_init abi))
            (target Reg (load_symbol_reloc (SymbolReloc.Absolute name 0)))
            (_ InstOutput (side_effect (abi_call_ind abi target uses defs))))
        (lower_call_rets abi defs (range (abi_first_ret sig_ref abi)
                                         (abi_num_rets abi)) (output_builder_new))))

;; Indirect call.
(rule (lower (call_indirect sig_ref ptr args))
      (let ((abi Sig (abi_sig sig_ref))
            (target Reg (put_in_reg ptr))
            (uses CallArgList (lower_call_args abi (range 0 (abi_num_args abi)) args))
            (defs CallRetList (defs_init abi))
            (_ InstOutput (side_effect (abi_call_ind abi target uses defs))))
        (lower_call_rets abi defs (range (abi_first_ret sig_ref abi)
                                         (abi_num_rets abi)) (output_builder_new))))

;; Lower function arguments.
(decl lower_call_args (Sig Range ValueSlice) CallArgList)
(rule (lower_call_args abi range args)
      (let ((uses CallArgListBuilder (args_builder_new))
            (stack MemArg (abi_call_stack_args abi))
            (_ InstOutput (lower_call_args_buffer abi stack range args))
            (_ InstOutput (lower_call_args_slots abi uses stack range args))
            (_ InstOutput (lower_call_ret_arg abi uses stack)))
        (args_builder_finish uses)))

;; Lower function return values by collecting them from registers / stack slots.
(decl lower_call_rets (Sig CallRetList Range InstOutputBuilder) InstOutput)
(rule (lower_call_rets abi _ (range_empty) builder) (output_builder_finish builder))
(rule (lower_call_rets abi defs (range_unwrap head tail) builder)
      (let ((ret ValueRegs (copy_from_arg defs (abi_lane_order abi)
                                          (abi_call_stack_rets abi)
                                          (abi_get_ret abi head)))
            (_ Unit (output_builder_push builder ret)))
        (lower_call_rets abi defs tail builder)))


;;;; Rules for `return_call` and `return_call_indirect` ;;;;;;;;;;;;;;;;;;;;;;;;

;; Direct tail call to an in-range function.
(rule 1 (lower (return_call (func_ref_data sig_ref name (reloc_distance_near)) args))
      (let ((abi Sig (abi_sig sig_ref))
            (uses CallArgList (lower_return_call_args abi (range 0 (abi_num_args abi)) args)))
        (side_effect (abi_return_call abi name uses))))

;; Direct tail call to an out-of-range function (implicitly via pointer).
(rule (lower (return_call (func_ref_data sig_ref name _) args))
      (let ((abi Sig (abi_sig sig_ref))
            (uses CallArgList (lower_return_call_args abi (range 0 (abi_num_args abi)) args))
            (target Reg (load_symbol_reloc (SymbolReloc.Absolute name 0))))
        (side_effect (abi_return_call_ind abi target uses))))

;; Indirect tail call.
(rule (lower (return_call_indirect sig_ref ptr args))
      (let ((abi Sig (abi_sig sig_ref))
            (target Reg (put_in_reg ptr))
            (uses CallArgList (lower_return_call_args abi (range 0 (abi_num_args abi)) args)))
        (side_effect (abi_return_call_ind abi target uses))))

;; Lower tail call function arguments.
(decl lower_return_call_args (Sig Range ValueSlice) CallArgList)
(rule (lower_return_call_args abi range args)
      (let ((uses CallArgListBuilder (args_builder_new))
            (stack MemArg (abi_return_call_stack_args abi))
            (_ InstOutput (lower_call_args_buffer abi stack range args))
            (_ InstOutput (lower_call_args_slots abi uses stack range args))
            (_ InstOutput (lower_return_call_ret_arg abi uses stack)))
        (args_builder_finish uses)))


;;;; Common helpers for argument lowering ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Lower function arguments (part 1): prepare buffer copies.
(decl lower_call_args_buffer (Sig MemArg Range ValueSlice) InstOutput)
(rule (lower_call_args_buffer abi _ (range_empty) _) (output_none))
(rule (lower_call_args_buffer abi stack (range_unwrap head tail) args)
      (let ((_ InstOutput (copy_to_buffer stack (abi_get_arg abi head)
                                          (value_slice_get args head))))
        (lower_call_args_buffer abi stack tail args)))

;; Lower function arguments (part 2): set up registers / stack slots.
(decl lower_call_args_slots (Sig CallArgListBuilder MemArg Range ValueSlice) InstOutput)
(rule (lower_call_args_slots abi _ _ (range_empty) _) (output_none))
(rule (lower_call_args_slots abi uses stack (range_unwrap head tail) args)
      (let ((_ InstOutput (copy_to_arg uses (abi_lane_order abi)
                                       stack (abi_get_arg abi head)
                                       (value_slice_get args head))))
        (lower_call_args_slots abi uses stack tail args)))

;; Lower function arguments (part 3): implicit return-area pointer (call).
(decl lower_call_ret_arg (Sig CallArgListBuilder MemArg) InstOutput)
(rule (lower_call_ret_arg (abi_no_ret_arg) _ _) (output_none))
(rule 1 (lower_call_ret_arg abi @ (abi_ret_arg (abi_arg_only_slot slot)) uses stack)
      (copy_reg_to_arg_slot uses (abi_lane_order abi)
                            stack slot (load_addr (abi_call_stack_rets abi))))

;; Lower function arguments (part 3): implicit return-area pointer (return call).
(decl lower_return_call_ret_arg (Sig CallArgListBuilder MemArg) InstOutput)
(rule (lower_return_call_ret_arg (abi_no_ret_arg) _ _) (output_none))
(rule 1 (lower_return_call_ret_arg abi @ (abi_ret_arg (abi_arg_only_slot slot)) uses stack)
      (copy_reg_to_arg_slot uses (abi_lane_order abi)
                            stack slot (abi_unwrap_ret_area_ptr)))


;;;; Rules for `get_{frame,stack}_pointer` and `get_return_address` ;;;;;;;;;;;;

(rule (lower (get_stack_pointer))
      (sp))

(rule (lower (get_frame_pointer))
      (load64 (memarg_frame_pointer_offset)))

(rule (lower (get_return_address))
      (load64 (memarg_return_address_offset)))