ValueTracking: Consider demanded elts for vector constants in computeKnownFPClass

Author: arsenm

llvm/lib/Analysis/ValueTracking.cpp

@@ -4524,6 +4524,9 @@ void computeKnownFPClass(const Value *V, const APInt &DemandedElts,
     // For vectors, verify that each element is not NaN.
     unsigned NumElts = VFVTy->getNumElements();
     for (unsigned i = 0; i != NumElts; ++i) {
+      if (!DemandedElts[i])
+        continue;
+
       Constant *Elt = CV->getAggregateElement(i);
       if (!Elt) {
         Known = KnownFPClass();

llvm/test/Transforms/Attributor/nofpclass.ll

@@ -1802,7 +1802,7 @@ define float @shufflevector_extractelt3(<2 x float> %arg0, <2 x float> nofpclass
 
 define float @shufflevector_constantdatavector_demanded0() {
 ; CHECK: Function Attrs: mustprogress nofree norecurse nosync nounwind willreturn memory(none)
-; CHECK-LABEL: define nofpclass(snan inf nzero sub nnorm) float @shufflevector_constantdatavector_demanded0
+; CHECK-LABEL: define nofpclass(nan inf zero sub nnorm) float @shufflevector_constantdatavector_demanded0
 ; CHECK-SAME: () #[[ATTR3]] {
 ; CHECK-NEXT:    [[SHUFFLE:%.*]] = shufflevector <3 x float> <float 1.000000e+00, float 0x7FF8000000000000, float 0.000000e+00>, <3 x float> poison, <2 x i32> <i32 0, i32 2>
 ; CHECK-NEXT:    [[EXTRACT:%.*]] = extractelement <2 x float> [[SHUFFLE]], i32 0
@@ -1815,7 +1815,7 @@ define float @shufflevector_constantdatavector_demanded0() {
 
 define float @shufflevector_constantdatavector_demanded1() {
 ; CHECK: Function Attrs: mustprogress nofree norecurse nosync nounwind willreturn memory(none)
-; CHECK-LABEL: define nofpclass(snan inf nzero sub nnorm) float @shufflevector_constantdatavector_demanded1
+; CHECK-LABEL: define nofpclass(nan inf nzero sub norm) float @shufflevector_constantdatavector_demanded1
 ; CHECK-SAME: () #[[ATTR3]] {
 ; CHECK-NEXT:    [[SHUFFLE:%.*]] = shufflevector <3 x float> <float 1.000000e+00, float 0x7FF8000000000000, float 0.000000e+00>, <3 x float> poison, <2 x i32> <i32 0, i32 2>
 ; CHECK-NEXT:    [[EXTRACT:%.*]] = extractelement <2 x float> [[SHUFFLE]], i32 1