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cranelift: Optimize select+icmp into {s,u}{min,max} (#5546)

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* cranelift: Optimize `select+icmp` into `{s,u}{min,max}`

* cranelift: Add generic egraph icmp reverse rule

* cranelift: Optimize `vselect+icmp` into `{s,u}{min,max}`

* cranelift: Optimize some `vselect+fcmp` into `f{min,max}_pseudo`

* cranelift: Add inverted forms of min/max rules
This commit is contained in:
Afonso Bordado
2023-02-15 23:06:21 +00:00
committed by GitHub
parent f0137c2618
commit 76539ef9f2
4 changed files with 438 additions and 1 deletions
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128
cranelift/codegen/src/opts/algebraic.isle
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@@ -345,3 +345,131 @@
(uextend $I64 x @ (value_type $I32))
(iconst _ (u64_from_imm64 0))))
(iconst ty (imm64 1)))
;; Transform select-of-icmp into {u,s}{min,max} instructions where possible.
(rule (simplify
(select ty (icmp _ (IntCC.SignedGreaterThan) x y) x y))
(smax ty x y))
(rule (simplify
(select ty (icmp _ (IntCC.SignedGreaterThanOrEqual) x y) x y))
(smax ty x y))
(rule (simplify
(select ty (icmp _ (IntCC.UnsignedGreaterThan) x y) x y))
(umax ty x y))
(rule (simplify
(select ty (icmp _ (IntCC.UnsignedGreaterThanOrEqual) x y) x y))
(umax ty x y))
(rule (simplify
(select ty (icmp _ (IntCC.SignedLessThan) x y) x y))
(smin ty x y))
(rule (simplify
(select ty (icmp _ (IntCC.SignedLessThanOrEqual) x y) x y))
(smin ty x y))
(rule (simplify
(select ty (icmp _ (IntCC.UnsignedLessThan) x y) x y))
(umin ty x y))
(rule (simplify
(select ty (icmp _ (IntCC.UnsignedLessThanOrEqual) x y) x y))
(umin ty x y))
;; These are the same rules as above, but when the operands for select are swapped
(rule (simplify
(select ty (icmp _ (IntCC.SignedLessThan) x y) y x))
(smax ty x y))
(rule (simplify
(select ty (icmp _ (IntCC.SignedLessThanOrEqual) x y) y x))
(smax ty x y))
(rule (simplify
(select ty (icmp _ (IntCC.UnsignedLessThan) x y) y x))
(umax ty x y))
(rule (simplify
(select ty (icmp _ (IntCC.UnsignedLessThanOrEqual) x y) y x))
(umax ty x y))
(rule (simplify
(select ty (icmp _ (IntCC.SignedGreaterThan) x y) y x))
(smin ty x y))
(rule (simplify
(select ty (icmp _ (IntCC.SignedGreaterThanOrEqual) x y) y x))
(smin ty x y))
(rule (simplify
(select ty (icmp _ (IntCC.UnsignedGreaterThan) x y) y x))
(umin ty x y))
(rule (simplify
(select ty (icmp _ (IntCC.UnsignedGreaterThanOrEqual) x y) y x))
(umin ty x y))
;; Transform vselect-of-icmp into {u,s}{min,max} instructions where possible.
(rule (simplify
(vselect ty (icmp _ (IntCC.SignedGreaterThan) x y) x y))
(smax ty x y))
(rule (simplify
(vselect ty (icmp _ (IntCC.SignedGreaterThanOrEqual) x y) x y))
(smax ty x y))
(rule (simplify
(vselect ty (icmp _ (IntCC.UnsignedGreaterThan) x y) x y))
(umax ty x y))
(rule (simplify
(vselect ty (icmp _ (IntCC.UnsignedGreaterThanOrEqual) x y) x y))
(umax ty x y))
(rule (simplify
(vselect ty (icmp _ (IntCC.SignedLessThan) x y) x y))
(smin ty x y))
(rule (simplify
(vselect ty (icmp _ (IntCC.SignedLessThanOrEqual) x y) x y))
(smin ty x y))
(rule (simplify
(vselect ty (icmp _ (IntCC.UnsignedLessThan) x y) x y))
(umin ty x y))
(rule (simplify
(vselect ty (icmp _ (IntCC.UnsignedLessThanOrEqual) x y) x y))
(umin ty x y))
;; These are the same rules as above, but when the operands for select are swapped
(rule (simplify
(vselect ty (icmp _ (IntCC.SignedLessThan) x y) y x))
(smax ty x y))
(rule (simplify
(vselect ty (icmp _ (IntCC.SignedLessThanOrEqual) x y) y x))
(smax ty x y))
(rule (simplify
(vselect ty (icmp _ (IntCC.UnsignedLessThan) x y) y x))
(umax ty x y))
(rule (simplify
(vselect ty (icmp _ (IntCC.UnsignedLessThanOrEqual) x y) y x))
(umax ty x y))
(rule (simplify
(vselect ty (icmp _ (IntCC.SignedGreaterThan) x y) y x))
(smin ty x y))
(rule (simplify
(vselect ty (icmp _ (IntCC.SignedGreaterThanOrEqual) x y) y x))
(smin ty x y))
(rule (simplify
(vselect ty (icmp _ (IntCC.UnsignedGreaterThan) x y) y x))
(umin ty x y))
(rule (simplify
(vselect ty (icmp _ (IntCC.UnsignedGreaterThanOrEqual) x y) y x))
(umin ty x y))
;; For floats convert fcmp lt into pseudo_min and gt into pseudo_max
;;
;; fmax_pseudo docs state:
;; The behaviour for this operations is defined as fmax_pseudo(a, b) = (a < b) ? b : a, and the behaviour for zero
;; or NaN inputs follows from the behaviour of < with such inputs.
;;
;; That is exactly the operation that we match here!
(rule (simplify
(select ty (fcmp _ (FloatCC.LessThan) x y) x y))
(fmin_pseudo ty x y))
(rule (simplify
(select ty (fcmp _ (FloatCC.GreaterThan) x y) x y))
(fmax_pseudo ty x y))
;; Do the same for vectors
(rule (simplify
(vselect ty (fcmp _ (FloatCC.LessThan) x y) x y))
(fmin_pseudo ty x y))
(rule (simplify
(vselect ty (fcmp _ (FloatCC.GreaterThan) x y) x y))
(fmax_pseudo ty x y))