Index: llvm/lib/Analysis/ValueTracking.cpp
===================================================================
--- llvm/lib/Analysis/ValueTracking.cpp
+++ llvm/lib/Analysis/ValueTracking.cpp
@@ -4616,8 +4616,9 @@
         Op->getOpcode() == Instruction::FAdd &&
         (InterestedClasses & (fcNegative & ~fcNegZero)) != fcNone;
     bool WantNaN = (InterestedClasses & fcNan) != fcNone;
+    bool WantNegZero = (InterestedClasses & fcNegZero) != fcNone;
 
-    if (!WantNaN && !WantNegative)
+    if (!WantNaN && !WantNegative && !WantNegZero)
       break;
 
     computeKnownFPClass(Op->getOperand(1), DemandedElts, fcNan | fcInf,