/// Mark predicate values currently being processed by isImpliedCond.
DenseSet<Value*> PendingLoopPredicates;
- /// ExitLimit - Information about the number of loop iterations for
- /// which a loop exit's branch condition evaluates to the not-taken path.
- /// This is a temporary pair of exact and max expressions that are
- /// eventually summarized in ExitNotTakenInfo and BackedgeTakenInfo.
+ /// ExitLimit - Information about the number of loop iterations for which a
+ /// loop exit's branch condition evaluates to the not-taken path. This is a
+ /// temporary pair of exact and max expressions that are eventually
+ /// summarized in ExitNotTakenInfo and BackedgeTakenInfo.
+ ///
+ /// If MustExit is true, then the exit must be taken when the BECount
+ /// reaches Exact (and before surpassing Max). If MustExit is false, then
+ /// BECount may exceed Exact or Max if the loop exits via another branch. In
+ /// either case, the loop may exit early via another branch.
+ ///
+ /// MustExit is true for most cases. However, an exit guarded by an
+ /// (in)equality on a nonunit stride may be skipped.
struct ExitLimit {
const SCEV *Exact;
const SCEV *Max;
+ bool MustExit;
- /*implicit*/ ExitLimit(const SCEV *E) : Exact(E), Max(E) {}
+ /*implicit*/ ExitLimit(const SCEV *E)
+ : Exact(E), Max(E), MustExit(true) {}
- ExitLimit(const SCEV *E, const SCEV *M) : Exact(E), Max(M) {}
+ ExitLimit(const SCEV *E, const SCEV *M, bool MustExit)
+ : Exact(E), Max(M), MustExit(MustExit) {}
/// hasAnyInfo - Test whether this ExitLimit contains any computed
/// information, or whether it's all SCEVCouldNotCompute values.
/// disconnect it from a def-use chain linking it to a loop.
void forgetValue(Value *V);
+ /// \brief Called when the client has changed the disposition of values in
+ /// this loop.
+ ///
+ /// We don't have a way to invalidate per-loop dispositions. Clear and
+ /// recompute is simpler.
+ void forgetLoopDispositions(const Loop *L) { LoopDispositions.clear(); }
+
/// GetMinTrailingZeros - Determine the minimum number of zero bits that S
/// is guaranteed to end in (at every loop iteration). It is, at the same
/// time, the minimum number of times S is divisible by 2. For example,