A couple of small refactorings to the egraph elaboration pass #7304
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@jameysharp and I noticed a couple of refactoring opportunities while reading through the elaboration pass: * The elaboration loop doesn't need to match on the top of the stack as a reference, because each case pops it immediately. Instead we can pop and match on the popped value. * Computing the cost of a `Result` value that's not in the DFG was using the block that contains the instruction to determine the level, but since the instruction is already known to not be in the DFG, this would default to `LoopLevel::root()` unconditionally. This also meant that the `Cost::at_level` function turned into an identity function on the cost given, making it unnecessary. Co-authored-by: Jamey Sharp <jsharp@fastly.com>
elliottt
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cfallin
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cfallin
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Oct 19, 2023
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LGTM! Good find w.r.t. the loop-level cost factor being a no-op; I suspect this was left over from an earlier version of extraction. I'd be interested to hear any thoughts you or others have about using the loop level somehow, but I'm happy to see this merged for now!
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@jameysharp and I noticed a couple of refactoring opportunities while reading through the elaboration pass:
ValueDef::Resultwas using the block that contains the instruction to determine the level, but since pure values will not be in the DFG yet, this would default toLoopLevel::root()unconditionally. This also meant that theCost::at_levelfunction turned into an identity function on the cost given, making it unnecessary.Co-authored-by: Jamey Sharp jsharp@fastly.com