C++: Fix off–by-one in range analysis for RemExpr.#6315
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rdmarsh2 merged 3 commits intogithub:mainfrom Jul 16, 2021
Merged
C++: Fix off–by-one in range analysis for RemExpr.#6315rdmarsh2 merged 3 commits intogithub:mainfrom
RemExpr.#6315rdmarsh2 merged 3 commits intogithub:mainfrom
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rdmarsh2
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Jul 16, 2021
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This PR fixes two bugs related to range analysis of
RemExpr:81aa115 fixes a bug where the sign of both the left-hand side, and the right-hand side of the
RemExprwas used instead of the right-hand side only.This caused expressions like
my_signed_int % 5to receive incorrect upper bounds, and because the lower-bound calculation ofRemExprdepended on the upper-bound, such expressions would also receive incorrect lower-bound values. See dc2eea5 for an example of this.39d9395 fixes an off-by-one bug where we'd conclude that
x % ywas upper-bounded by the value ofy, whereas in reality we could refine this toy - 1.The last bug caused a false-positive in #6081. I recommend commit-by-commit reviewing of this PR.