C++: x != 0 support in SimpleRangeAnalysis#4131
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lcartey wants to merge 1 commit intogithub:mainfrom
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Currently != does not infer any bounds beyonds those implied by the type. However, if the rhs is a constant at the start or end of the type range, then we can infer slightly tighter bounds.
MathiasVP
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Aug 25, 2020
| // For x != RHS, we create bounds based on the size of the type, adjusted according to the RHS bounds: | ||
| // 1. if lowerbound(RHS) == typeUpperBound(RHS.getUnspecifiedType()) == upperbound(RHS) | ||
| // then | ||
| // x < lowerbound(RHS) |
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I'm certainly buying the soundness of this, but I think it's more clear if we change this line to x < typeUpperBound(RHS.getUnspecifiedType()) to match the else case. That way, it's clear that the only change in the inferred bound is replacing a <= with a <.
And similarly for the second case below.
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Agreed. Also, isn't it overly detailed to call getUnspecifiedType in pseudocode? What if I just remove that?
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Superseded by #4204 |
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Currently != does not infer any bounds beyonds those implied by the type. However, if the rhs is a constant at the start or end of the type range, then we can infer slightly tighter bounds.