1 files changed, 14 insertions, 7 deletions
diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index 24adfa3..0990a0d 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -11418,8 +11418,7 @@ bool ScalarEvolution::isKnownPredicateViaNoOverflow(CmpPredicate Pred,
       XNonConstOp = X;
       XFlagsPresent = ExpectedFlags;
     }
-    if (!isa<SCEVConstant>(XConstOp) ||
-        (XFlagsPresent & ExpectedFlags) != ExpectedFlags)
+    if (!isa<SCEVConstant>(XConstOp))
       return false;
 
     if (!splitBinaryAdd(Y, YConstOp, YNonConstOp, YFlagsPresent)) {
@@ -11428,12 +11427,20 @@ bool ScalarEvolution::isKnownPredicateViaNoOverflow(CmpPredicate Pred,
       YFlagsPresent = ExpectedFlags;
     }
 
-    if (!isa<SCEVConstant>(YConstOp) ||
-        (YFlagsPresent & ExpectedFlags) != ExpectedFlags)
+    if (YNonConstOp != XNonConstOp)
       return false;
 
-    if (YNonConstOp != XNonConstOp)
+    if (!isa<SCEVConstant>(YConstOp))
+      return false;
+
+    // When matching ADDs with NUW flags (and unsigned predicates), only the
+    // second ADD (with the larger constant) requires NUW.
+    if ((YFlagsPresent & ExpectedFlags) != ExpectedFlags)
+      return false;
+    if (ExpectedFlags != SCEV::FlagNUW &&
+        (XFlagsPresent & ExpectedFlags) != ExpectedFlags) {
       return false;
+    }
 
     OutC1 = cast<SCEVConstant>(XConstOp)->getAPInt();
     OutC2 = cast<SCEVConstant>(YConstOp)->getAPInt();
@@ -11472,7 +11479,7 @@ bool ScalarEvolution::isKnownPredicateViaNoOverflow(CmpPredicate Pred,
     std::swap(LHS, RHS);
     [[fallthrough]];
   case ICmpInst::ICMP_ULE:
-    // (X + C1)<nuw> u<= (X + C2)<nuw> for C1 u<= C2.
+    // (X + C1) u<= (X + C2)<nuw> for C1 u<= C2.
     if (MatchBinaryAddToConst(LHS, RHS, C1, C2, SCEV::FlagNUW) && C1.ule(C2))
       return true;
 
@@ -11482,7 +11489,7 @@ bool ScalarEvolution::isKnownPredicateViaNoOverflow(CmpPredicate Pred,
     std::swap(LHS, RHS);
     [[fallthrough]];
   case ICmpInst::ICMP_ULT:
-    // (X + C1)<nuw> u< (X + C2)<nuw> if C1 u< C2.
+    // (X + C1) u< (X + C2)<nuw> if C1 u< C2.
     if (MatchBinaryAddToConst(LHS, RHS, C1, C2, SCEV::FlagNUW) && C1.ult(C2))
       return true;
     break;