[InstCombine] Allow folding with two constant arms

Author: dtcxzyw

llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp

@@ -2709,7 +2709,8 @@ Instruction *InstCombinerImpl::visitCallInst(CallInst &CI) {
 
     if (match(Arg, m_Select(m_Value(Cond), m_Value(TVal), m_Value(FVal)))) {
       // fabs (select Cond, TrueC, FalseC) --> select Cond, AbsT, AbsF
-      if (Arg->hasOneUse() && (isa<Constant>(TVal) || isa<Constant>(FVal))) {
+      if (Arg->hasOneUse() ? (isa<Constant>(TVal) || isa<Constant>(FVal))
+                           : (isa<Constant>(TVal) && isa<Constant>(FVal))) {
         CallInst *AbsT = Builder.CreateCall(II->getCalledFunction(), {TVal});
         CallInst *AbsF = Builder.CreateCall(II->getCalledFunction(), {FVal});
         SelectInst *SI = SelectInst::Create(Cond, AbsT, AbsF);

llvm/test/Transforms/InstCombine/intrinsic-select.ll

@@ -363,7 +363,7 @@ define float @test_fabs_select_multiuse_both_constant(i1 %cond, float %x) {
 ; CHECK-LABEL: @test_fabs_select_multiuse_both_constant(
 ; CHECK-NEXT:    [[SELECT:%.*]] = select i1 [[COND:%.*]], float -1.000000e+00, float -2.000000e+00
 ; CHECK-NEXT:    call void @usef32(float [[SELECT]])
-; CHECK-NEXT:    [[FABS:%.*]] = call float @llvm.fabs.f32(float [[SELECT]])
+; CHECK-NEXT:    [[FABS:%.*]] = select i1 [[COND]], float 1.000000e+00, float 2.000000e+00
 ; CHECK-NEXT:    ret float [[FABS]]
 ;
   %select = select i1 %cond, float -1.0, float -2.0