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Revert "Cranelift: Rewrite or(and(x, y), not(y)) => or(x, not(y)) (#5676)" (#5682)

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This reverts commit 8c9eb9939b.

Fixes #5680
This commit is contained in:
Trevor Elliott
2023-01-31 18:53:23 -08:00
committed by GitHub
parent 0c66a1bba7
commit 268f6bfc1d
5 changed files with 1 additions and 112 deletions
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27
cranelift/codegen/src/opts/algebraic.isle
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@@ -138,33 +138,6 @@
(rule (simplify (bnot ty (band t x y)))
(bor ty (bnot ty x) (bnot ty y)))
;; `or(and(x, y), not(y)) == or(x, not(y))`
(rule (simplify (bor ty
(band ty x y)
z @ (bnot ty y)))
(bor ty x z))
;; Duplicate the rule but swap the `bor` operands because `bor` is
;; commutative. We could, of course, add a `simplify` rule to do the commutative
;; swap for all `bor`s but this will bloat the e-graph with many e-nodes. It is
;; cheaper to have additional rules, rather than additional e-nodes, because we
;; amortize their cost via ISLE's smart codegen.
(rule (simplify (bor ty
z @ (bnot ty y)
(band ty x y)))
(bor ty x z))
;; `or(and(x, y), not(y)) == or(x, not(y))` specialized for constants, since
;; otherwise we may not know that `z == not(y)` since we don't generally expand
;; constants in the e-graph.
;;
;; (No need to duplicate for commutative `bor` for this constant version because
;; we move constants to the right.)
(rule (simplify (bor ty
(band ty x (iconst ty (u64_from_imm64 y)))
z @ (iconst ty (u64_from_imm64 zk))))
(if (u64_eq zk (u64_not y)))
(bor ty x z))
;; x*2 == 2*x == x+x.
(rule (simplify (imul ty x (iconst _ (simm32 2))))
(iadd ty x x))