forked from OSchip/llvm-project
3f0e4ad833
Summary: When constructing the predicate P1 in ScalarEvolution::createAddRecFromPHIWithCastsImpl() it is possible for the PHISCEV from which the predicate is constructed to be a SCEVConstant instead of a SCEVAddRec. If this happens, then the cast<SCEVAddRec>(PHISCEV) in the code will assert. Such a PHISCEV is possible if either the start value or the accumulator value is a constant value that not equal to its truncated value, and if the truncated value is zero. This patch adds tests that demonstrate the cast<> assertion, and fixes this problem by checking whether the PHISCEV is a constant before constructing the P1 predicate; if it is, then P1 is equivalent to one of P2 or P3. Additionally, if we know that the start value or accumulator value are constants then we check whether the P2 and/or P3 predicates are known false at compile time; if either is, then we bail out of constructing the AddRec. Reviewers: sanjoy, mkazantsev, silviu.baranga Reviewed By: mkazantsev Subscribers: mkazantsev, llvm-commits Differential Revision: https://reviews.llvm.org/D37265 llvm-svn: 312568 |
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