ConstraintAnalysis: Add OR fusing of { x == C || x > C } => x >= C#8936
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| checkOr(left7, right, right); | ||
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| // Change 5 on the left to 99: | ||
| // { x == 99 } || { x > 5 && x <= 42 } ==> { x > 5 } |
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Can have a TODO for adding x <= 99 to the result.
| checkOr(left99, right, rightOnly5); | ||
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| // Change 5 on the left to 4: | ||
| // { x == 4 } || { x > 5 && x <= 42 } ==> { x <= 42 } |
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Similarly, we can have a TODO for adding x >= 4.
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| // Changes to operations: | ||
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| // Change the Eq on the left to Ne. We fail to find anything for the OR. |
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TODO the result could be x != 5.
| checkOr(leftNe, right, empty); | ||
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| // Change the GtS on the right to GtU: | ||
| // { x == 5 } || { x >U 5 && x <= 42 } ==> { x <= 42 } |
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I assume this will be improved in the next PR?
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Eventually, yes, though maybe not the next PR. I'm trying to prove out the path to getting some specific Kotlin code working. I'll fill out related cases later.
Co-authored-by: Thomas Lively <tlively123@gmail.com>
Co-authored-by: Thomas Lively <tlively123@gmail.com>
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In general it seems profitable to "lift" pairs of greater-than and less-than bounds on constants as well as equality bounds with constants to intervals, do the join on the intervals, then lower them back to individual bounds. |
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Agreed, lifting to intervals internally may make sense here. |
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This is common in loops, where there is an initial value + a backedge that
has an incremented but bounded value.
To implement this, add full expansion of the OR of two AndedConstraintSets
into ANDs of the ORs of all their elements, and thorough checking there.