// The BackedgeTaken expression contains the number of times that the
// backedge branches to the loop header. This is one less than the
// number of times the loop executes, so use the incremented indvar.
- llvm::Value *IncrementedIndvar = IndVar->getIncomingValueForBlock(L->getExitingBlock());
+ llvm::Value *IncrementedIndvar =
+ IndVar->getIncomingValueForBlock(L->getExitingBlock());
const auto *IncrementedIndvarSCEV =
cast<SCEVAddRecExpr>(SE->getSCEV(IncrementedIndvar));
// It is unsafe to use the incremented indvar if it has a wrapping flag, we
// don't want to compare against a poison value. Check the SCEV that
// corresponds to the incremented indvar, the SCEVExpander will only insert
// flags in the IR if the SCEV originally had wrapping flags.
- if (ScalarEvolution::maskFlags(IncrementedIndvarSCEV->getNoWrapFlags(),
- SCEV::FlagNUW | SCEV::FlagNSW) ==
- SCEV::FlagAnyWrap) {
+ // 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.
+ if (!ScalarEvolution::maskFlags(IncrementedIndvarSCEV->getNoWrapFlags(),
+ SCEV::FlagNUW | SCEV::FlagNSW)) {
// 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().