;; Prelude definitions specific to the mid-end.

;; Any `extern` definitions here are generally implemented in `src/opts.rs`.

;;;;; eclass and enode access ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Extract any node(s) for the given eclass ID.
(decl multi inst_data (Type InstructionData) Value)
(extern extractor inst_data inst_data_etor)

;; Identical to `inst_data`, just with a different ISLE type.
;; This is basically a manual version of `curry`/`uncurry` in Haskell:
;; to compose extractors the outer one needs to be single-parameter,
;; so this combines the two parameters of `inst_data` into one.
(type TypeAndInstructionData (primitive TypeAndInstructionData))
(decl multi inst_data_tupled (TypeAndInstructionData) Value)
(extern extractor inst_data_tupled inst_data_tupled_etor)

;; Construct a pure node, returning a new (or deduplicated
;; already-existing) eclass ID.
(decl make_inst (Type InstructionData) Value)
(extern constructor make_inst make_inst_ctor)

;; Constructors for value arrays.
(decl value_array_2_ctor (Value Value) ValueArray2)
(extern constructor value_array_2_ctor value_array_2_ctor)
(decl value_array_3_ctor (Value Value Value) ValueArray3)
(extern constructor value_array_3_ctor value_array_3_ctor)

(rule (eq ty x y) (icmp ty (IntCC.Equal) x y))
(rule (ne ty x y) (icmp ty (IntCC.NotEqual) x y))
(rule (ult ty x y) (icmp ty (IntCC.UnsignedLessThan) x y))
(rule (ule ty x y) (icmp ty (IntCC.UnsignedLessThanOrEqual) x y))
(rule (ugt ty x y) (icmp ty (IntCC.UnsignedGreaterThan) x y))
(rule (uge ty x y) (icmp ty (IntCC.UnsignedGreaterThanOrEqual) x y))
(rule (slt ty x y) (icmp ty (IntCC.SignedLessThan) x y))
(rule (sle ty x y) (icmp ty (IntCC.SignedLessThanOrEqual) x y))
(rule (sgt ty x y) (icmp ty (IntCC.SignedGreaterThan) x y))
(rule (sge ty x y) (icmp ty (IntCC.SignedGreaterThanOrEqual) x y))

;; 3-way comparison, returning -1/0/+1 in I8
(decl spaceship_s (Type Value Value) Value)
(rule (spaceship_s ty x y) (isub $I8 (sgt ty x y) (slt ty x y)))
(extractor (spaceship_s ty x y) (isub $I8 (sgt ty x y) (slt ty x y)))
(decl spaceship_u (Type Value Value) Value)
(rule (spaceship_u ty x y) (isub $I8 (ugt ty x y) (ult ty x y)))
(extractor (spaceship_u ty x y) (isub $I8 (ugt ty x y) (ult ty x y)))

;;;;; optimization toplevel ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; The main matcher rule invoked by the toplevel driver.
(decl multi simplify (Value) Value)

;; Mark a node as requiring remat when used in a different block.
(decl remat (Value) Value)
(extern constructor remat remat)

;; Mark a node as subsuming whatever else it's rewritten from -- this
;; is definitely preferable, not just a possible option. Useful for,
;; e.g., constant propagation where we arrive at a definite "final
;; answer".
(decl subsume (Value) Value)
(extern constructor subsume subsume)

;;;;; constructors ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(decl iconst_sextend_etor (Type i64) TypeAndInstructionData)
(extern extractor iconst_sextend_etor iconst_sextend_etor)

;; Construct an `iconst` from an `i64` or Extract an `i64` from an `iconst`
;; by treating the constant as signed.
;; When extracting, smaller types get their value sign-extended to 64-bits,
;; so that `iconst.i8 255` will give you a `-1_i64`.
;; When constructing, the rule will fail if the value cannot be represented in
;; the target type.  If it fits, it'll be masked accordingly in the constant.
(decl iconst_s (Type i64) Value)
(extractor (iconst_s ty c) (inst_data_tupled (iconst_sextend_etor ty c)))
(rule 0 (iconst_s ty c)
	(if-let c_masked (u64_and (i64_as_u64 c) (ty_umax ty)))
	(if-let c_reextended (i64_sextend_u64 ty c_masked))
	(if-let true (u64_eq (i64_as_u64 c) (i64_as_u64 c_reextended)))
	(iconst ty (imm64 c_masked)))
(rule 1 (iconst_s $I128 c) (sextend $I128 (iconst_s $I64 c)))

;; Construct an `iconst` from a `u64` or Extract a `u64` from an `iconst`
;; by treating the constant as unsigned.
;; When extracting, smaller types get their value zero-extended to 64-bits,
;; so that `iconst.i8 255` will give you a `255_u64`.
;; When constructing, the rule will fail if the value cannot be represented in
;; the target type.
(decl iconst_u (Type u64) Value)
(extractor (iconst_u ty c) (iconst ty (u64_from_imm64 c)))
(rule 0 (iconst_u ty c)
	(if-let true (u64_le c (ty_umax ty)))
    (iconst ty (imm64 c)))
(rule 1 (iconst_u $I128 c) (uextend $I128 (iconst_u $I64 c)))

;; These take `Value`, rather than going through `inst_data_tupled`, because
;; most of the time they want to return the original `Value`, and it would be
;; a waste to need to re-GVN the instruction data in those cases.
(decl multi sextend_maybe_etor (Type Value) Value)
(extern extractor infallible sextend_maybe_etor sextend_maybe_etor)
(decl multi uextend_maybe_etor (Type Value) Value)
(extern extractor infallible uextend_maybe_etor uextend_maybe_etor)

;; Match or Construct a possibly-`uextend`ed value.
;; Gives the extended-to type and inner value when matching something that was
;; extended, or the input value and its type when the value isn't an extension.
;; Useful to write a single pattern that can match things that may or may not
;; have undergone C's "usual arithmetic conversions".
;; When generating values, extending to the same type is invalid CLIF,
;; so this avoids doing that where there's no extension actually needed.
(decl uextend_maybe (Type Value) Value)
(extractor (uextend_maybe ty val) (uextend_maybe_etor ty val))
(rule 0 (uextend_maybe ty val) (uextend ty val))
(rule 1 (uextend_maybe ty val@(value_type ty)) val)

;; Same as `uextend_maybe` above, just for `sextend`.
(decl sextend_maybe (Type Value) Value)
(extractor (sextend_maybe ty val) (sextend_maybe_etor ty val))
(rule 0 (sextend_maybe ty val) (sextend ty val))
(rule 1 (sextend_maybe ty val@(value_type ty)) val)