[ValueTracking] add logic for known-never-nan with minnum/maxnum

From the LangRef: "Returns NaN only if both operands are NaN."

llvm-svn: 360206

1 files changed, 5 insertions, 0 deletions

diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index 7c16b21c928..54575441b71 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -3136,6 +3136,11 @@ bool llvm::isKnownNeverNaN(const Value *V, const TargetLibraryInfo *TLI,
     case Intrinsic::sqrt:
       return isKnownNeverNaN(II->getArgOperand(0), TLI, Depth + 1) &&
              CannotBeOrderedLessThanZero(II->getArgOperand(0), TLI);
+    case Intrinsic::minnum:
+    case Intrinsic::maxnum:
+      // If either operand is not NaN, the result is not NaN.
+      return isKnownNeverNaN(II->getArgOperand(0), TLI, Depth + 1) ||
+             isKnownNeverNaN(II->getArgOperand(1), TLI, Depth + 1);
     default:
       return false;
     }