[analysis] Implement a Lift lattice #6040
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Current dependencies on/for this PR:
This stack of pull requests is managed by Graphite. |
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| namespace wasm::analysis { | ||
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| template<Lattice L> struct Lift { |
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Perhaps a comment on what Lift means?
| bool isBottom() const noexcept { return !this->has_value(); } | ||
| bool operator==(const Element& other) const noexcept { | ||
| return (isBottom() && other.isBottom()) || | ||
| (!isBottom() && !other.isBottom() && **this == *other); |
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Why wouldn't **this == *other work if both are bottom?
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We can't evaluate **this if isBottom because that would be dereferencing an empty optional.
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Ah, I see, then the new bottom element is basically the "nothing" case of the optional? So the extra bit of the optional marks that new item, basically. That's what I was missing.
At the risk of seeming repetitive: comments 😃
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| template<Lattice L> struct Lift { | ||
| struct Element : std::optional<typename L::Element> { | ||
| bool isBottom() const noexcept { return !this->has_value(); } |
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How should I read this has_value? Do we use the empty optional as the bottom perhaps?
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Yes, exactly. I'll add a comment.
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I've now improved or added doc comments to every PR in this stack. |
This lattice "lifts" another lattice by inserting a new bottom element underneath it.
This lattice "lifts" another lattice by inserting a new bottom element underneath it.
This lattice "lifts" another lattice by inserting a new bottom element
underneath it.