Index: llvm/lib/Analysis/ValueTracking.cpp
===================================================================
--- llvm/lib/Analysis/ValueTracking.cpp
+++ llvm/lib/Analysis/ValueTracking.cpp
@@ -4516,11 +4516,21 @@
   case Instruction::FAdd:
   case Instruction::FSub: {
     KnownFPClass KnownLHS, KnownRHS;
+
+    bool WantNegative =
+        Op->getOpcode() == Instruction::FAdd &&
+        (InterestedClasses & (fcNegative & ~fcNegZero)) != fcNone;
+    bool WantNaN = (InterestedClasses & fcNan) != fcNone;
+
+    if (!WantNaN && !WantNegative)
+      break;
+
     computeKnownFPClass(Op->getOperand(1), DemandedElts, fcNan | fcInf,
                         KnownRHS, Depth + 1, Q, TLI);
 
-    if (KnownRHS.isKnownNeverNaN() || KnownRHS.isKnownNeverNegZero() ||
-        (Opc == Instruction::FSub && KnownRHS.isKnownNeverPosZero())) {
+    if ((WantNaN && KnownRHS.isKnownNeverNaN()) ||
+        (WantNegative && KnownRHS.cannotBeOrderedLessThanZero()) ||
+        KnownRHS.isKnownNeverNegZero() || Opc == Instruction::FSub) {
       // RHS is canonically cheaper to compute. Skip inspecting the LHS if
       // there's no point.
       computeKnownFPClass(Op->getOperand(0), DemandedElts, fcNan | fcInf,
@@ -4533,6 +4543,10 @@
 
       const Function *F = cast<Instruction>(Op)->getFunction();
       if (Op->getOpcode() == Instruction::FAdd) {
+        if (KnownLHS.cannotBeOrderedLessThanZero() &&
+            KnownRHS.cannotBeOrderedLessThanZero())
+          Known.knownNot(fcNegative & ~fcNegZero);
+
         // (fadd x, 0.0) is guaranteed to return +0.0, not -0.0.
         if ((KnownLHS.isKnownNeverLogicalNegZero(*F, Op->getType()) ||
              KnownRHS.isKnownNeverLogicalNegZero(*F, Op->getType())) &&
Index: llvm/test/Transforms/Attributor/nofpclass.ll
===================================================================
--- llvm/test/Transforms/Attributor/nofpclass.ll
+++ llvm/test/Transforms/Attributor/nofpclass.ll
@@ -1559,7 +1559,7 @@
 
 define float @fsub_p0_commute(float %arg0) {
 ; CHECK: Function Attrs: nofree norecurse nosync nounwind willreturn memory(none)
-; CHECK-LABEL: define float @fsub_p0_commute
+; CHECK-LABEL: define nofpclass(nzero) float @fsub_p0_commute
 ; CHECK-SAME: (float [[ARG0:%.*]]) #[[ATTR2]] {
 ; CHECK-NEXT:    [[SUB:%.*]] = fsub float 0.000000e+00, [[ARG0]]
 ; CHECK-NEXT:    ret float [[SUB]]
@@ -1702,7 +1702,7 @@
 
 define float @fsub_p0_commute_ieee_daz(float %arg0) #2 {
 ; CHECK: Function Attrs: nofree norecurse nosync nounwind willreturn memory(none)
-; CHECK-LABEL: define float @fsub_p0_commute_ieee_daz
+; CHECK-LABEL: define nofpclass(nzero) float @fsub_p0_commute_ieee_daz
 ; CHECK-SAME: (float [[ARG0:%.*]]) #[[ATTR8]] {
 ; CHECK-NEXT:    [[SUB:%.*]] = fsub float 0.000000e+00, [[ARG0]]
 ; CHECK-NEXT:    ret float [[SUB]]
@@ -1834,7 +1834,7 @@
 
 define float @fadd_known_positive(float nofpclass(ninf nsub nnorm) %arg0, float nofpclass(ninf nsub nnorm) %arg1) {
 ; CHECK: Function Attrs: nofree norecurse nosync nounwind willreturn memory(none)
-; CHECK-LABEL: define float @fadd_known_positive
+; CHECK-LABEL: define nofpclass(ninf nsub nnorm) float @fadd_known_positive
 ; CHECK-SAME: (float nofpclass(ninf nsub nnorm) [[ARG0:%.*]], float nofpclass(ninf nsub nnorm) [[ARG1:%.*]]) #[[ATTR2]] {
 ; CHECK-NEXT:    [[ADD:%.*]] = fadd float [[ARG0]], [[ARG1]]
 ; CHECK-NEXT:    ret float [[ADD]]
@@ -1845,7 +1845,7 @@
 
 define float @fadd_known_positive_daz(float nofpclass(ninf nsub nnorm) %arg0, float nofpclass(ninf nsub nnorm) %arg1) #0 {
 ; CHECK: Function Attrs: nofree norecurse nosync nounwind willreturn memory(none)
-; CHECK-LABEL: define float @fadd_known_positive_daz
+; CHECK-LABEL: define nofpclass(ninf nsub nnorm) float @fadd_known_positive_daz
 ; CHECK-SAME: (float nofpclass(ninf nsub nnorm) [[ARG0:%.*]], float nofpclass(ninf nsub nnorm) [[ARG1:%.*]]) #[[ATTR7]] {
 ; CHECK-NEXT:    [[ADD:%.*]] = fadd float [[ARG0]], [[ARG1]]
 ; CHECK-NEXT:    ret float [[ADD]]
@@ -1856,7 +1856,7 @@
 
 define float @fadd_known_positive_nzero_lhs(float nofpclass(ninf nsub nnorm nzero) %arg0, float nofpclass(ninf nsub nnorm) %arg1) {
 ; CHECK: Function Attrs: nofree norecurse nosync nounwind willreturn memory(none)
-; CHECK-LABEL: define float @fadd_known_positive_nzero_lhs
+; CHECK-LABEL: define nofpclass(ninf nzero nsub nnorm) float @fadd_known_positive_nzero_lhs
 ; CHECK-SAME: (float nofpclass(ninf nzero nsub nnorm) [[ARG0:%.*]], float nofpclass(ninf nsub nnorm) [[ARG1:%.*]]) #[[ATTR2]] {
 ; CHECK-NEXT:    [[ADD:%.*]] = fadd float [[ARG0]], [[ARG1]]
 ; CHECK-NEXT:    ret float [[ADD]]
@@ -1867,7 +1867,7 @@
 
 define float @fadd_known_positive_nzero_rhs(float nofpclass(ninf nsub nnorm) %arg0, float nofpclass(ninf nsub nnorm nzero) %arg1) {
 ; CHECK: Function Attrs: nofree norecurse nosync nounwind willreturn memory(none)
-; CHECK-LABEL: define nofpclass(nzero) float @fadd_known_positive_nzero_rhs
+; CHECK-LABEL: define nofpclass(ninf nzero nsub nnorm) float @fadd_known_positive_nzero_rhs
 ; CHECK-SAME: (float nofpclass(ninf nsub nnorm) [[ARG0:%.*]], float nofpclass(ninf nzero nsub nnorm) [[ARG1:%.*]]) #[[ATTR2]] {
 ; CHECK-NEXT:    [[ADD:%.*]] = fadd float [[ARG0]], [[ARG1]]
 ; CHECK-NEXT:    ret float [[ADD]]
@@ -1878,7 +1878,7 @@
 
 define float @fadd_known_positive_nzero(float nofpclass(ninf nsub nnorm nzero) %arg0, float nofpclass(ninf nsub nnorm nzero) %arg1) {
 ; CHECK: Function Attrs: nofree norecurse nosync nounwind willreturn memory(none)
-; CHECK-LABEL: define nofpclass(nzero) float @fadd_known_positive_nzero
+; CHECK-LABEL: define nofpclass(ninf nzero nsub nnorm) float @fadd_known_positive_nzero
 ; CHECK-SAME: (float nofpclass(ninf nzero nsub nnorm) [[ARG0:%.*]], float nofpclass(ninf nzero nsub nnorm) [[ARG1:%.*]]) #[[ATTR2]] {
 ; CHECK-NEXT:    [[ADD:%.*]] = fadd float [[ARG0]], [[ARG1]]
 ; CHECK-NEXT:    ret float [[ADD]]
@@ -1889,7 +1889,7 @@
 
 define float @fadd_known_positive_nzero_ftz_daz(float nofpclass(ninf nsub nnorm nzero) %arg0, float nofpclass(ninf nsub nnorm nzero) %arg1) #0 {
 ; CHECK: Function Attrs: nofree norecurse nosync nounwind willreturn memory(none)
-; CHECK-LABEL: define float @fadd_known_positive_nzero_ftz_daz
+; CHECK-LABEL: define nofpclass(ninf nsub nnorm) float @fadd_known_positive_nzero_ftz_daz
 ; CHECK-SAME: (float nofpclass(ninf nzero nsub nnorm) [[ARG0:%.*]], float nofpclass(ninf nzero nsub nnorm) [[ARG1:%.*]]) #[[ATTR7]] {
 ; CHECK-NEXT:    [[ADD:%.*]] = fadd float [[ARG0]], [[ARG1]]
 ; CHECK-NEXT:    ret float [[ADD]]
@@ -1900,7 +1900,7 @@
 
 define float @fadd_known_positive_nzero_ftz(float nofpclass(ninf nsub nnorm nzero) %arg0, float nofpclass(ninf nsub nnorm nzero) %arg1) #1 {
 ; CHECK: Function Attrs: nofree norecurse nosync nounwind willreturn memory(none)
-; CHECK-LABEL: define float @fadd_known_positive_nzero_ftz
+; CHECK-LABEL: define nofpclass(ninf nsub nnorm) float @fadd_known_positive_nzero_ftz
 ; CHECK-SAME: (float nofpclass(ninf nzero nsub nnorm) [[ARG0:%.*]], float nofpclass(ninf nzero nsub nnorm) [[ARG1:%.*]]) #[[ATTR10]] {
 ; CHECK-NEXT:    [[ADD:%.*]] = fadd float [[ARG0]], [[ARG1]]
 ; CHECK-NEXT:    ret float [[ADD]]
@@ -1911,7 +1911,7 @@
 
 define float @fadd_known_positive_nzero_daz(float nofpclass(ninf nsub nnorm nzero) %arg0, float nofpclass(ninf nsub nnorm nzero) %arg1) #2 {
 ; CHECK: Function Attrs: nofree norecurse nosync nounwind willreturn memory(none)
-; CHECK-LABEL: define nofpclass(nzero) float @fadd_known_positive_nzero_daz
+; CHECK-LABEL: define nofpclass(ninf nzero nsub nnorm) float @fadd_known_positive_nzero_daz
 ; CHECK-SAME: (float nofpclass(ninf nzero nsub nnorm) [[ARG0:%.*]], float nofpclass(ninf nzero nsub nnorm) [[ARG1:%.*]]) #[[ATTR8]] {
 ; CHECK-NEXT:    [[ADD:%.*]] = fadd float [[ARG0]], [[ARG1]]
 ; CHECK-NEXT:    ret float [[ADD]]