[ValueTracking] Recognize that and(x, add (x, -1)) clears the low bit

[oota-llvm.git] / lib / Analysis / ScalarEvolution.cpp

diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp
index 53e63d70a3e887c55d2ad1b3cab0fe886e8ad934..c2db02fe85a49aaa5cfef7ed849a84e30f9dbdfb 100644 (file)
--- a/lib/Analysis/ScalarEvolution.cpp
+++ b/lib/Analysis/ScalarEvolution.cpp
@@ -7385,6 +7385,7 @@ bool ScalarEvolution::isKnownPredicateViaNoOverflow(ICmpInst::Predicate Pred,
     if (MatchBinaryAddToConst(LHS, RHS, C, SCEV::FlagNSW) &&
         !C.isStrictlyPositive())
       return true;
+    break;
 
   case ICmpInst::ICMP_SGT:
     std::swap(LHS, RHS);
@@ -7397,6 +7398,7 @@ bool ScalarEvolution::isKnownPredicateViaNoOverflow(ICmpInst::Predicate Pred,
     // (X + C)<nsw> s< X if C < 0
     if (MatchBinaryAddToConst(LHS, RHS, C, SCEV::FlagNSW) && C.isNegative())
       return true;
+    break;
   }
 
   return false;
@@ -7419,12 +7421,9 @@ bool ScalarEvolution::isKnownPredicateViaSplitting(ICmpInst::Predicate Pred,
   // expensive; and using isKnownNonNegative(RHS) is sufficient for most of the
   // interesting cases seen in practice.  We can consider "upgrading" L >= 0 to
   // use isKnownPredicate later if needed.
-  if (isKnownNonNegative(RHS) &&
-      isKnownPredicate(CmpInst::ICMP_SGE, LHS, getZero(LHS->getType())) &&
-      isKnownPredicate(CmpInst::ICMP_SLT, LHS, RHS))
-    return true;
-
-  return false;
+  return isKnownNonNegative(RHS) &&
+         isKnownPredicate(CmpInst::ICMP_SGE, LHS, getZero(LHS->getType())) &&
+         isKnownPredicate(CmpInst::ICMP_SLT, LHS, RHS);
 }
 
 /// isLoopBackedgeGuardedByCond - Test whether the backedge of the loop is