[InstCombine] Fix flag propagation in foldSelectIntoOp

Author: dtcxzyw

llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp

@@ -544,8 +544,11 @@ Instruction *InstCombinerImpl::foldSelectIntoOp(SelectInst &SI, Value *TrueVal,
 
     Value *NewSel = Builder.CreateSelect(SI.getCondition(), Swapped ? C : OOp,
                                          Swapped ? OOp : C, "", &SI);
-    if (isa<FPMathOperator>(&SI))
+    if (isa<FPMathOperator>(&SI)) {
       cast<Instruction>(NewSel)->setFastMathFlags(FMF);
+      if (!TVI->hasNoInfs() && !FMF.noNaNs())
+        cast<Instruction>(NewSel)->setHasNoInfs(false);
+    }
     NewSel->takeName(TVI);
     BinaryOperator *BO =
         BinaryOperator::Create(TVI->getOpcode(), FalseVal, NewSel);

llvm/test/Transforms/InstCombine/select-binop-foldable-floating-point.ll

@@ -36,7 +36,7 @@ define float @select_fpclass_fadd_ninf1(i1 %cond, float nofpclass(nan) %A, float
 
 define float @select_fpclass_fadd_ninf2(i1 %cond, float nofpclass(nan) %A, float %B) {
 ; CHECK-LABEL: @select_fpclass_fadd_ninf2(
-; CHECK-NEXT:    [[C:%.*]] = select ninf i1 [[COND:%.*]], float [[B:%.*]], float -0.000000e+00
+; CHECK-NEXT:    [[C:%.*]] = select i1 [[COND:%.*]], float [[B:%.*]], float -0.000000e+00
 ; CHECK-NEXT:    [[D:%.*]] = fadd float [[A:%.*]], [[C]]
 ; CHECK-NEXT:    ret float [[D]]
 ;