Index: llvm/lib/Analysis/ValueTracking.cpp
===================================================================
--- llvm/lib/Analysis/ValueTracking.cpp
+++ llvm/lib/Analysis/ValueTracking.cpp
@@ -4619,6 +4619,14 @@
       Known.SignBit = std::nullopt;
     break;
   }
+  case Instruction::FPTrunc: {
+    KnownFPClass KnownSrc;
+    computeKnownFPClass(Op->getOperand(0), DemandedElts,
+                        InterestedClasses, KnownSrc, Depth + 1, Q, TLI);
+    if (KnownSrc.isKnownNeverNaN())
+      Known.knownNot(fcNan);
+    break;
+  }
   case Instruction::SIToFP:
   case Instruction::UIToFP: {
     // Cannot produce nan
Index: llvm/test/Transforms/Attributor/nofpclass-fptrunc.ll
===================================================================
--- llvm/test/Transforms/Attributor/nofpclass-fptrunc.ll
+++ llvm/test/Transforms/Attributor/nofpclass-fptrunc.ll
@@ -12,7 +12,7 @@
 }
 
 define float @ret_fptrunc_nonan(double nofpclass(nan) %arg0) {
-; CHECK-LABEL: define float @ret_fptrunc_nonan
+; CHECK-LABEL: define nofpclass(nan) float @ret_fptrunc_nonan
 ; CHECK-SAME: (double nofpclass(nan) [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fptrunc double [[ARG0]] to float
 ; CHECK-NEXT:    ret float [[EXT]]
@@ -102,7 +102,7 @@
 }
 
 define float @ret_fptrunc_nonan_noinf(double nofpclass(nan inf) %arg0) {
-; CHECK-LABEL: define float @ret_fptrunc_nonan_noinf
+; CHECK-LABEL: define nofpclass(nan) float @ret_fptrunc_nonan_noinf
 ; CHECK-SAME: (double nofpclass(nan inf) [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fptrunc double [[ARG0]] to float
 ; CHECK-NEXT:    ret float [[EXT]]