diff options
Diffstat (limited to 'llvm/lib/Transforms/Scalar/IndVarSimplify.cpp')
| -rw-r--r-- | llvm/lib/Transforms/Scalar/IndVarSimplify.cpp | 23 |
1 files changed, 22 insertions, 1 deletions
diff --git a/llvm/lib/Transforms/Scalar/IndVarSimplify.cpp b/llvm/lib/Transforms/Scalar/IndVarSimplify.cpp index bf90912ebd0..fc6d1837060 100644 --- a/llvm/lib/Transforms/Scalar/IndVarSimplify.cpp +++ b/llvm/lib/Transforms/Scalar/IndVarSimplify.cpp @@ -1719,8 +1719,29 @@ LinearFunctionTestReplace(Loop *L, // FIXME: In theory, SCEV could drop flags even though they exist in IR. // A more robust solution would involve getting a new expression for // CmpIndVar by applying non-NSW/NUW AddExprs. + auto WrappingFlags = + ScalarEvolution::setFlags(SCEV::FlagNUW, SCEV::FlagNSW); + const SCEV *IVInit = IncrementedIndvarSCEV->getStart(); + if (SE->getTypeSizeInBits(IVInit->getType()) > + SE->getTypeSizeInBits(IVCount->getType())) + IVInit = SE->getTruncateExpr(IVInit, IVCount->getType()); + unsigned BitWidth = SE->getTypeSizeInBits(IVCount->getType()); + Type *WideTy = IntegerType::get(SE->getContext(), BitWidth + 1); + // Check if InitIV + BECount+1 requires sign/zero extension. + // If not, clear the corresponding flag from WrappingFlags because it is not + // necessary for those flags in the IncrementedIndvarSCEV expression. + if (SE->getSignExtendExpr(SE->getAddExpr(IVInit, BackedgeTakenCount), + WideTy) == + SE->getAddExpr(SE->getSignExtendExpr(IVInit, WideTy), + SE->getSignExtendExpr(BackedgeTakenCount, WideTy))) + WrappingFlags = ScalarEvolution::clearFlags(WrappingFlags, SCEV::FlagNSW); + if (SE->getZeroExtendExpr(SE->getAddExpr(IVInit, BackedgeTakenCount), + WideTy) == + SE->getAddExpr(SE->getZeroExtendExpr(IVInit, WideTy), + SE->getZeroExtendExpr(BackedgeTakenCount, WideTy))) + WrappingFlags = ScalarEvolution::clearFlags(WrappingFlags, SCEV::FlagNUW); if (!ScalarEvolution::maskFlags(IncrementedIndvarSCEV->getNoWrapFlags(), - SCEV::FlagNUW | SCEV::FlagNSW)) { + WrappingFlags)) { // Add one to the "backedge-taken" count to get the trip count. // This addition may overflow, which is valid as long as the comparison is // truncated to BackedgeTakenCount->getType(). |
