Simplify SwitchInt handling
#133328
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Simplify SwitchInt handling
#133328
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I tried reordering this method to more closely match `MaybeUninitializedPlaces::apply_terminator_effect`, but doing so breaks tests.
Current `SwitchInt` handling has complicated control flow. - The dataflow engine calls `Analysis::apply_switch_int_edge_effects`, passing in an "applier" that impls `SwitchIntEdgeEffects`. - `apply_switch_int_edge_effects` possibly calls `apply` on the applier, passing it a closure. - The `apply` method calls the closure on each `SwitchInt` edge. - The closure operates on the edge. I.e. control flow goes from the engine, to the analysis, to the applier (which came from the engine), to the closure (which came from the analysis). It took me a while to work this out. This commit changes to a simpler structure that maintains the important characteristics. - The dataflow engine calls `Analysis::get_switch_int_data`. - `get_switch_int_data` returns an `Option<Self::SwitchIntData>` value. - If that returned value was `Some`, the dataflow engine calls `Analysis::apply_switch_int_edge_effect` on each edge, passing the `Self::SwitchIntData` value. - `Analysis::apply_switch_int_edge_effect` operates on the edge. I.e. control flow goes from the engine, to the analysis, to the engine, to the analysis. Added: - The `Analysis::SwitchIntData` assoc type and the `Analysis::get_switch_int_data` method. Both only need to be defined by analyses that look at `SwitchInt` terminators. - The `MaybePlacesSwitchIntData` struct, which has three fields. Changes: - `Analysis::apply_switch_int_edge_effects` becomes `Analysis::apply_switch_int_edge_effect`, which is a little simpler because it's dealing with a single edge instead of all edges. Removed: - The `SwitchIntEdgeEffects` trait, and its two impls: `BackwardSwitchIntEdgeEffectsApplier` (which has six fields) and `ForwardSwitchIntEdgeEffectsApplier` structs (which has four fields). - The closure. The new structure is more concise and simpler.
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Details in the individual commits. Let me know if I am sending you too many reviews, I can reassign if necessary. It's worth noting my motivation for this change. I wanted to try making |
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Dataflow handling of
SwitchIntis currently complicated. This PR simplifies it.r? @cjgillot