;; Constant propagation.

(rule (simplify
       (iadd (fits_in_64 ty)
             (iconst ty (u64_from_imm64 k1))
             (iconst ty (u64_from_imm64 k2))))
      (subsume (iconst ty (imm64_masked ty (u64_add k1 k2)))))

(rule (simplify
       (isub (fits_in_64 ty)
             (iconst ty (u64_from_imm64 k1))
             (iconst ty (u64_from_imm64 k2))))
      (subsume (iconst ty (imm64_masked ty (u64_sub k1 k2)))))

(rule (simplify
       (imul (fits_in_64 ty)
             (iconst ty (u64_from_imm64 k1))
             (iconst ty (u64_from_imm64 k2))))
      (subsume (iconst ty (imm64_masked ty (u64_mul k1 k2)))))

(rule (simplify
       (sdiv (fits_in_64 ty)
             (iconst ty (u64_from_imm64 k1))
             (iconst ty (u64_from_imm64 k2))))
      (if-let d (u64_sdiv k1 k2))
      (subsume (iconst ty (imm64_masked ty d))))

(rule (simplify
       (udiv (fits_in_64 ty)
             (iconst ty (u64_from_imm64 k1))
             (iconst ty (u64_from_imm64 k2))))
      (if-let d (u64_udiv k1 k2))
      (subsume (iconst ty (imm64_masked ty d))))

(rule (simplify
       (bor (fits_in_64 ty)
            (iconst ty (u64_from_imm64 k1))
            (iconst ty (u64_from_imm64 k2))))
      (subsume (iconst ty (imm64_masked ty (u64_or k1 k2)))))

(rule (simplify
       (band (fits_in_64 ty)
            (iconst ty (u64_from_imm64 k1))
            (iconst ty (u64_from_imm64 k2))))
      (subsume (iconst ty (imm64_masked ty (u64_and k1 k2)))))

(rule (simplify
       (bxor (fits_in_64 ty)
            (iconst ty (u64_from_imm64 k1))
            (iconst ty (u64_from_imm64 k2))))
      (subsume (iconst ty (imm64_masked ty (u64_xor k1 k2)))))

(rule (simplify
       (bnot (fits_in_64 ty)
            (iconst ty (u64_from_imm64 k))))
      (subsume (iconst ty (imm64_masked ty (u64_not k)))))

(rule (simplify (ishl (fits_in_64 ty)
                      (iconst ty k1)
                      (iconst _ k2)))
      (subsume (iconst ty (imm64_shl ty k1 k2))))

(rule (simplify (ushr (fits_in_64 ty)
                      (iconst ty k1)
                      (iconst _ k2)))
      (subsume (iconst ty (imm64_ushr ty k1 k2))))

(rule (simplify (sshr (fits_in_64 ty)
                      (iconst ty k1)
                      (iconst _ k2)))
      (subsume (iconst ty (imm64_sshr ty k1 k2))))

(rule (simplify (uextend (fits_in_64 wide) (iconst narrow imm)))
      (subsume (iconst wide (imm64 (u64_uextend_imm64 narrow imm)))))

(rule (simplify (sextend (fits_in_64 wide) (iconst narrow imm)))
      (subsume (iconst wide (imm64_masked wide (i64_as_u64 (i64_sextend_imm64 narrow imm))))))

(rule (simplify
       (icmp result_ty
            cc
            (iconst ty k1)
            (iconst ty k2)))
      (subsume (iconst result_ty (imm64_icmp ty cc k1 k2))))


;; Canonicalize via commutativity: push immediates to the right.
;;
;;   (op k x) --> (op x k)

(rule (simplify
       (iadd ty k @ (iconst ty _) x))
      (iadd ty x k))
;; sub is not commutative, but we can flip the args and negate the
;; whole thing.
(rule (simplify
       (isub ty k @ (iconst ty _) x))
      (ineg ty (isub ty x k)))
(rule (simplify
       (imul ty k @ (iconst ty _) x))
      (imul ty x k))

(rule (simplify
       (bor ty k @ (iconst ty _) x))
      (bor ty x k))
(rule (simplify
       (band ty k @ (iconst ty _) x))
      (band ty x k))
(rule (simplify
       (bxor ty k @ (iconst ty _) x))
      (bxor ty x k))

(rule (simplify
       (icmp ty cc k @ (iconst _ _) x))
      (icmp ty (intcc_reverse cc) x k))

;; Canonicalize via associativity: reassociate to a right-heavy tree
;; for constants.
;;
;;   (op (op x k) k) --> (op x (op k k))

(rule (simplify
       (iadd ty (iadd ty x k1 @ (iconst ty _)) k2 @ (iconst ty _)))
      (iadd ty x (iadd ty k1 k2)))
;; sub is not directly associative, but we can flip a sub to an add to
;; make it work:
;; - (sub (sub x k1) k2) -> (sub x (add k1 k2))
;; - (sub (sub k1 x) k2) -> (sub (sub k1 k2) x)
;; - (sub (add x k1) k2) -> (sub x (sub k2 k1))
;; - (add (sub x k1) k2) -> (add x (sub k2 k1))
;; - (add (sub k1 x) k2) -> (sub (add k1 k2) x)
(rule (simplify (isub ty
                      (isub ty x (iconst ty (u64_from_imm64 k1)))
                      (iconst ty (u64_from_imm64 k2))))
      (isub ty x (iconst ty (imm64_masked ty (u64_add k1 k2)))))
(rule (simplify (isub ty
                      (isub ty (iconst ty (u64_from_imm64 k1)) x)
                      (iconst ty (u64_from_imm64 k2))))
      (isub ty (iconst ty (imm64_masked ty (u64_sub k1 k2))) x))
(rule (simplify (isub ty
                      (iadd ty x (iconst ty (u64_from_imm64 k1)))
                      (iconst ty (u64_from_imm64 k2))))
      (isub ty x (iconst ty (imm64_masked ty (u64_sub k2 k1)))))
(rule (simplify (iadd ty
                      (isub ty x (iconst ty (u64_from_imm64 k1)))
                      (iconst ty (u64_from_imm64 k2))))
      (iadd ty x (iconst ty (imm64_masked ty (u64_sub k2 k1)))))
(rule (simplify (iadd ty
                      (isub ty (iconst ty (u64_from_imm64 k1)) x)
                      (iconst ty (u64_from_imm64 k2))))
      (isub ty (iconst ty (imm64_masked ty (u64_add k1 k2))) x))

(rule (simplify
       (imul ty (imul ty x k1 @ (iconst ty _)) k2 @ (iconst ty _)))
      (imul ty x (imul ty k1 k2)))
(rule (simplify
       (bor ty (bor ty x k1 @ (iconst ty _)) k2 @ (iconst ty _)))
      (bor ty x (bor ty k1 k2)))
(rule (simplify
       (band ty (band ty x k1 @ (iconst ty _)) k2 @ (iconst ty _)))
      (band ty x (band ty k1 k2)))
(rule (simplify
       (bxor ty (bxor ty x k1 @ (iconst ty _)) k2 @ (iconst ty _)))
      (bxor ty x (bxor ty k1 k2)))

(rule (simplify
       (select ty (iconst _ (u64_from_imm64 (u64_nonzero _))) x y))
      x)
(rule (simplify
       (select ty (iconst _ (u64_from_imm64 0)) x y))
      y)

;; TODO: fadd, fsub, fmul, fdiv, fneg, fabs

;; A splat of a constant can become a direct `vconst` with the appropriate bit
;; pattern.
(rule (simplify (splat dst (iconst $I8 n)))
      (vconst dst (splat8 (u64_uextend_imm64 $I8 n))))
(rule (simplify (splat dst (iconst $I16 n)))
      (vconst dst (splat16 (u64_uextend_imm64 $I16 n))))
(rule (simplify (splat dst (iconst $I32 n)))
      (vconst dst (splat32 (u64_uextend_imm64 $I32 n))))
(rule (simplify (splat dst (iconst $I64 n)))
      (vconst dst (splat64 (u64_uextend_imm64 $I64 n))))
(rule (simplify (splat dst (f32const _ (u32_from_ieee32 n))))
      (vconst dst (splat32 n)))
(rule (simplify (splat dst (f64const _ (u64_from_ieee64 n))))
      (vconst dst (splat64 n)))

(decl splat8 (u64) Constant)
(rule (splat8 n) (splat16 (u64_or n (u64_shl n 8))))
(decl splat16 (u64) Constant)
(rule (splat16 n) (splat32 (u64_or n (u64_shl n 16))))
(decl splat32 (u64) Constant)
(rule (splat32 n) (splat64 (u64_or n (u64_shl n 32))))
(decl splat64 (u64) Constant)
(extern constructor splat64 splat64)