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Cranelift: add/modify mid-end opt rules #14296

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Merged
cfallin merged 1 commit into from
Sep 8, 2026
Merged

Cranelift: add/modify mid-end opt rules #14296

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58 changes: 31 additions & 27 deletions cranelift/codegen/src/opts/arithmetic.isle
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Original file line number Diff line number Diff line change
Expand Up @@ -7,16 +7,16 @@
;; x+0 == x.
(rule iadd_x_plus_zero (simplify (iadd ty
x
(iconst_u ty 0)))
(all_zero ty)))
(subsume x))
;; x-0 == x.
(rule (simplify (isub ty
x
(iconst_u ty 0)))
(all_zero ty)))
(subsume x))
;; 0-x == (ineg x).
(rule (simplify (isub ty
(iconst_u ty 0)
(all_zero ty)
x))
(ineg ty x))

Expand Down Expand Up @@ -47,7 +47,7 @@
(subsume inner))

;; x-x == 0.
(rule (simplify (isub ty x x)) (subsume (iconst_u ty 0)))
(rule (simplify (isub ty x x)) (subsume (all_zero ty)))

;; x*1 == x.
(rule (simplify (imul ty
Expand All @@ -58,7 +58,7 @@
;; x*0 == 0.
(rule (simplify (imul ty
_
zero @ (iconst_u ty 0)))
zero @ (all_zero ty)))
(subsume zero))

;; x*-1 == ineg(x).
Expand Down Expand Up @@ -127,9 +127,9 @@
(apply_div_const_magic_s64 (Opcode.Sdiv) x d))

;; x % 1 == 0
(rule (simplify_skeleton (urem x (iconst_u ty 1))) (iconst_u ty 0))
(rule (simplify_skeleton (srem x (iconst_u ty 1))) (iconst_u ty 0))
(rule (simplify_skeleton (srem x (iconst_s ty -1))) (iconst_u ty 0))
(rule (simplify_skeleton (urem x (iconst_u ty 1))) (all_zero ty))
(rule (simplify_skeleton (srem x (iconst_u ty 1))) (all_zero ty))
(rule (simplify_skeleton (srem x (iconst_s ty -1))) (all_zero ty))

;; Unsigned `x % d == x & ((1 << ilog2(d)) - 1)` when `d` is a power of two.
(rule (simplify_skeleton (urem x (iconst_u ty (u64_extract_power_of_two d))))
Expand Down Expand Up @@ -340,7 +340,7 @@
(rule (simplify (isub ty (iadd ty y x) (iadd ty z x))) (isub ty y z))

;; (x - y) + (y - x) --> 0
(rule (simplify (iadd ty (isub ty x y) (isub ty y x))) (subsume (iconst_u ty 0)))
(rule (simplify (iadd ty (isub ty x y) (isub ty y x))) (subsume (all_zero ty)))

;; ((x - z) - (y - z)) --> (x - y)
(rule (simplify (isub ty (isub ty x z) (isub ty y z))) (isub ty x y))
Expand Down Expand Up @@ -392,7 +392,7 @@

;; Helper to create a "true" value for a comparison. For scalar integers this is
;; a value of 1 but for vectors this is -1 since each lane is filled with all
;; 1s. We use `(iconst_u ty 0)` for falses for both integers and vector. This is
;; 1s. We use `(all_zero ty)` for falses for both integers and vectors. This is
;; because of the Cranelift semantics:
;; When comparing scalars, the result is 1 if the condition holds, or 0 otherwise.
;; When comparing vectors, the result is -1 (all-ones) if the condition holds, or 0 otherwise.
Expand All @@ -407,18 +407,18 @@
(rule (simplify (eq ty (iadd cty y x) (iadd cty y x))) (cmp_true ty))

;; (x - y) != x --> y != 0
(rule (simplify (ne cty (isub ty x y) x)) (ne cty y (iconst_u ty 0)))
(rule (simplify (ne cty x (isub ty x y))) (ne cty y (iconst_u ty 0)))
(rule (simplify (ne cty (isub ty x y) x)) (ne cty y (all_zero ty)))
(rule (simplify (ne cty x (isub ty x y))) (ne cty y (all_zero ty)))

;; (x - y) == x --> y == 0
(rule (simplify (eq cty (isub ty x y) x)) (eq cty y (iconst_u ty 0)))
(rule (simplify (eq cty x (isub ty x y))) (eq cty y (iconst_u ty 0)))
(rule (simplify (eq cty (isub ty x y) x)) (eq cty y (all_zero ty)))
(rule (simplify (eq cty x (isub ty x y))) (eq cty y (all_zero ty)))

;; (x + y) == y --> x == 0
(rule (simplify (eq cty (iadd ty x y) y)) (eq cty x (iconst_u ty 0)))
(rule (simplify (eq cty (iadd ty y x) y)) (eq cty x (iconst_u ty 0)))
(rule (simplify (eq cty y (iadd ty x y))) (eq cty x (iconst_u ty 0)))
(rule (simplify (eq cty y (iadd ty y x))) (eq cty x (iconst_u ty 0)))
(rule (simplify (eq cty (iadd ty x y) y)) (eq cty x (all_zero ty)))
(rule (simplify (eq cty (iadd ty y x) y)) (eq cty x (all_zero ty)))
(rule (simplify (eq cty y (iadd ty x y))) (eq cty x (all_zero ty)))
(rule (simplify (eq cty y (iadd ty y x))) (eq cty x (all_zero ty)))

;; -x == -y --> x == y
(rule (simplify (eq ty (ineg ty x) (ineg ty y))) (eq ty x y))
Expand Down Expand Up @@ -574,14 +574,14 @@
(rule (simplify (umax ty (umin ty x y) (umax ty y x))) (umax ty x y))

;; x > max(x, y) --> 0
(rule (simplify (sgt ty x (smax ty x y))) (iconst_u ty 0))
(rule (simplify (sgt ty x (smax ty y x))) (iconst_u ty 0))
(rule (simplify (slt ty (smax ty x y) x)) (iconst_u ty 0))
(rule (simplify (slt ty (smax ty y x) x)) (iconst_u ty 0))
(rule (simplify (ugt ty x (umax ty x y))) (iconst_u ty 0))
(rule (simplify (ugt ty x (umax ty y x))) (iconst_u ty 0))
(rule (simplify (ult ty (umax ty x y) x)) (iconst_u ty 0))
(rule (simplify (ult ty (umax ty y x) x)) (iconst_u ty 0))
(rule (simplify (sgt ty x (smax ty x y))) (all_zero ty))
(rule (simplify (sgt ty x (smax ty y x))) (all_zero ty))
(rule (simplify (slt ty (smax ty x y) x)) (all_zero ty))
(rule (simplify (slt ty (smax ty y x) x)) (all_zero ty))
(rule (simplify (ugt ty x (umax ty x y))) (all_zero ty))
(rule (simplify (ugt ty x (umax ty y x))) (all_zero ty))
(rule (simplify (ult ty (umax ty x y) x)) (all_zero ty))
(rule (simplify (ult ty (umax ty y x) x)) (all_zero ty))

;; (-X) * C = X * (-C)
(rule imul_ineg_const (simplify (imul (fits_in_64 ty) (ineg ty x) (iconst ty y))) (imul ty x (iconst ty (imm64_neg ty y))))
Expand Down Expand Up @@ -619,4 +619,8 @@
(rule (simplify (imul ty (umax ty (ineg ty x) x) (umax ty (ineg ty x) x))) (imul ty x x))
(rule (simplify (imul ty (umax ty (ineg ty x) x) (umax ty x (ineg ty x)))) (imul ty x x))
(rule (simplify (imul ty (umax ty x (ineg ty x)) (umax ty (ineg ty x) x))) (imul ty x x))
(rule (simplify (imul ty (umax ty x (ineg ty x)) (umax ty x (ineg ty x)))) (imul ty x x))
(rule (simplify (imul ty (umax ty x (ineg ty x)) (umax ty x (ineg ty x)))) (imul ty x x))

;; x /u (1 << y) --> x >>u y
(rule (simplify_skeleton (udiv x (ishl ty (iconst_u ty 1) y)))
(ushr ty x y))
49 changes: 45 additions & 4 deletions cranelift/codegen/src/opts/bitops.isle
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Original file line number Diff line number Diff line change
Expand Up @@ -117,19 +117,19 @@
(rule (truthy (popcnt _ x)) x)
(rule (truthy (rotl _ x _)) x)
(rule (truthy (rotr _ x _)) x)
(rule (truthy (select _ x (iconst_u _ (u64_when_non_zero)) (iconst_u _ 0))) x)
(rule (truthy (select _ x (iconst_u _ (u64_when_non_zero)) (all_zero _))) x)
;; (ne ty (iconst 0) v) is also canonicalized into this form via another rule
(rule (truthy (ne _ x (iconst_u _ 0))) x)
(rule (truthy (ne _ x (all_zero _))) x)

;; All of these expressions don't care about their input as long as it is truthy.
;; so we can remove expressions that preserve that property from the input.
(rule (simplify (bmask ty v)) (if-let x (truthy v)) (bmask ty x))
(rule (simplify (select ty v t f)) (if-let c (truthy v)) (select ty c t f))
;; (ne ty (iconst 0) v) is also canonicalized into this form via another rule
(rule (simplify (ne cty v (iconst_u _ 0)))
(rule (simplify (ne cty v (all_zero _)))
(if-let c (truthy v))
(if-let (value_type (ty_int_ref_scalar_64_extract ty)) c)
(ne cty c (iconst_u ty 0)))
(ne cty c (all_zero ty)))



Expand Down Expand Up @@ -790,3 +790,44 @@

;; popcnt(bitrev(x)) == popcnt(x)
(rule (simplify (popcnt ty (bitrev ty x))) (popcnt ty x))

;; (x ^ y) ^ (x ^ z) --> y ^ z.
(rule (simplify (bxor ty (bxor ty x y) (bxor ty x z))) (subsume (bxor ty y z)))
(rule (simplify (bxor ty (bxor ty x y) (bxor ty z x))) (subsume (bxor ty y z)))
(rule (simplify (bxor ty (bxor ty y x) (bxor ty x z))) (subsume (bxor ty y z)))
(rule (simplify (bxor ty (bxor ty y x) (bxor ty z x))) (subsume (bxor ty y z)))

;; (-x) & 1 --> x & 1.
(rule (simplify (band ty (ineg ty x) (iconst_u ty 1))) (band ty x (iconst_u ty 1)))

;; (x & y) & (x | z) --> x & y.
(rule (simplify (band ty (band ty x y) (bor ty x z))) (subsume (band ty x y)))
(rule (simplify (band ty (bor ty x z) (band ty x y))) (subsume (band ty x y)))
(rule (simplify (band ty (band ty x y) (bor ty z x))) (subsume (band ty x y)))
(rule (simplify (band ty (bor ty z x) (band ty x y))) (subsume (band ty x y)))
(rule (simplify (band ty (band ty y x) (bor ty x z))) (subsume (band ty x y)))
(rule (simplify (band ty (bor ty x z) (band ty y x))) (subsume (band ty x y)))
(rule (simplify (band ty (band ty y x) (bor ty z x))) (subsume (band ty x y)))
(rule (simplify (band ty (bor ty z x) (band ty y x))) (subsume (band ty x y)))

;; (x & y) | (x | z) --> x | z.
(rule (simplify (bor ty (band ty x y) (bor ty x z))) (subsume (bor ty x z)))
(rule (simplify (bor ty (bor ty x z) (band ty x y))) (subsume (bor ty x z)))
(rule (simplify (bor ty (band ty x y) (bor ty z x))) (subsume (bor ty x z)))
(rule (simplify (bor ty (bor ty z x) (band ty x y))) (subsume (bor ty x z)))
(rule (simplify (bor ty (band ty y x) (bor ty x z))) (subsume (bor ty x z)))
(rule (simplify (bor ty (bor ty x z) (band ty y x))) (subsume (bor ty x z)))
(rule (simplify (bor ty (band ty y x) (bor ty z x))) (subsume (bor ty x z)))
(rule (simplify (bor ty (bor ty z x) (band ty y x))) (subsume (bor ty x z)))

;; (x & y) | (x ^ y) --> x | y.
(rule (simplify (bor ty (band ty x y) (bxor ty x y))) (bor ty x y))
(rule (simplify (bor ty (bxor ty x y) (band ty x y))) (bor ty x y))
(rule (simplify (bor ty (band ty x y) (bxor ty y x))) (bor ty x y))
(rule (simplify (bor ty (bxor ty y x) (band ty x y))) (bor ty x y))

;; ~((~x) - y) --> x + y.
(rule (simplify (bnot ty (isub ty (bnot ty x) y))) (iadd ty x y))

;; ~((~x) >>s y) --> x >>s y.
(rule (simplify (bnot ty (sshr ty (bnot ty x) y))) (sshr ty x y))
2 changes: 1 addition & 1 deletion cranelift/codegen/src/opts/cprop.isle
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Expand Up @@ -226,7 +226,7 @@

(rule (simplify (select ty (iconst_u _ (u64_when_non_zero)) x _))
(subsume x))
(rule (simplify (select ty (iconst_u _ 0) _ y))
(rule (simplify (select ty (all_zero _) _ y))
(subsume y))

(rule (simplify
Expand Down
20 changes: 10 additions & 10 deletions cranelift/codegen/src/opts/extends.isle
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Original file line number Diff line number Diff line change
Expand Up @@ -28,22 +28,22 @@
(rule (simplify
(slt ty
(uextend $I64 x @ (value_type $I32))
(iconst_u _ 0)))
(subsume (iconst_u ty 0)))
(all_zero _)))
(subsume (all_zero ty)))
(rule (simplify
(sge ty
(uextend $I64 x @ (value_type $I32))
(iconst_u _ 0)))
(all_zero _)))
(subsume (iconst_u ty 1)))

;; Sign-extending can't change whether a number is zero nor how it signed-compares to zero
(rule (simplify (eq _ (sextend _ x@(value_type ty)) (iconst_s _ 0)))
(eq ty x (iconst_s ty 0)))
(rule (simplify (ne _ (sextend _ x@(value_type ty)) (iconst_s _ 0)))
(ne ty x (iconst_s ty 0)))
(rule (simplify (icmp _ cc (sextend _ x@(value_type ty)) (iconst_s _ 0)))
(rule (simplify (eq _ (sextend _ x@(value_type ty)) (all_zero _)))
(eq ty x (all_zero ty)))
(rule (simplify (ne _ (sextend _ x@(value_type ty)) (all_zero _)))
(ne ty x (all_zero ty)))
(rule (simplify (icmp _ cc (sextend _ x@(value_type ty)) (all_zero _)))
(if (signed_cond_code cc))
(icmp ty cc x (iconst_s ty 0)))
(icmp ty cc x (all_zero ty)))

;; A reduction-of-an-extend back to the same original type is the same as not
;; actually doing the extend in the first place.
Expand Down Expand Up @@ -91,7 +91,7 @@
(rule (simplify (ireduce ty (band _ x y))) (band ty (ireduce ty x) (ireduce ty y)))

;; Try to transform an `iconcat` into an i128 into either an sextend or uextend
(rule (simplify (iconcat $I128 x (iconst_u _ 0))) (uextend $I128 x))
(rule (simplify (iconcat $I128 x (all_zero _))) (uextend $I128 x))
(rule (simplify (iconcat $I128 x (sshr _ x (iconst_u _ 63)))) (sextend $I128 x))

;; Select narrowest type
Expand Down
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