34c0535844
This PR changes the AIG representation of constants from `const (b : Bool)` to a single constructor `false`. Since #7381 `Ref` contains an `invert` flag meaning the constant `true` can be represented as a `Ref` to `false` with `invert` set, so no expressivity is lost. The main advantage to this representation is that it allows pattern matching on constants to match just on the `invert` field rather than on both `invert` and the constant value or having to XOR the two together. This representation is also standard in other AIG frameworks, such as the [Aiger standard](https://fmv.jku.at/aiger/FORMAT.aiger). This PR also generalizes the idempotency rule in `mkGateCached` from `(a /\ b) = a` when `(a = b)` to also cover `(¬a /\ ¬b) = ¬a` when `a = b` as it was not covered.
53 lines
1.4 KiB
Text
53 lines
1.4 KiB
Text
import Std.Tactic.BVDecide.Bitblast
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open Std.Sat
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open Std.Tactic.BVDecide
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def mkFalseCollapsible (n : Nat) : BVLogicalExpr :=
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match n with
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| 0 => .const false
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| n + 1 =>
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let tree := mkFalseCollapsible n
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.gate .and tree tree
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/-- info: #[Std.Sat.AIG.Decl.false] -/
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#guard_msgs in
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#eval BVLogicalExpr.bitblast (mkFalseCollapsible 1) |>.aig.decls
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/-- info: #[Std.Sat.AIG.Decl.false] -/
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#guard_msgs in
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#eval BVLogicalExpr.bitblast (mkFalseCollapsible 16) |>.aig.decls
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def mkTrueCollapsible (n : Nat) : BVLogicalExpr :=
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match n with
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| 0 => .const true
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| n + 1 =>
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let tree := mkTrueCollapsible n
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.gate .and tree tree
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/-- info: #[Std.Sat.AIG.Decl.false] -/
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#guard_msgs in
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#eval BVLogicalExpr.bitblast (mkTrueCollapsible 1) |>.aig.decls
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/-- info: #[Std.Sat.AIG.Decl.false] -/
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#guard_msgs in
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#eval BVLogicalExpr.bitblast (mkTrueCollapsible 16) |>.aig.decls
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def mkConstantCollapsible (n : Nat) : BVLogicalExpr :=
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match n with
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| 0 => .const false
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| n + 1 =>
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let tree := mkTrueCollapsible n
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.gate .and (.gate .and tree tree) (.const false)
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/-- info: (1, Std.Sat.AIG.Decl.false) -/
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#guard_msgs in
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#eval
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let entry := BVLogicalExpr.bitblast (mkConstantCollapsible 1)
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(entry.aig.decls.size, entry.aig.decls[entry.ref.gate]!)
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/-- info: (1, Std.Sat.AIG.Decl.false) -/
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#guard_msgs in
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#eval
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let entry := BVLogicalExpr.bitblast (mkConstantCollapsible 16)
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(entry.aig.decls.size, entry.aig.decls[entry.ref.gate]!)
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