[InstCombine] Add one-use check when folding fabs over selects

Author: dtcxzyw

llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp

@@ -2709,7 +2709,7 @@ 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 (isa<Constant>(TVal) || isa<Constant>(FVal)) {
+      if (Arg->hasOneUse() && (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

@@ -350,8 +350,7 @@ define float @test_fabs_select_multiuse(i1 %cond, float %x) {
 ; CHECK-LABEL: @test_fabs_select_multiuse(
 ; CHECK-NEXT:    [[SELECT:%.*]] = select i1 [[COND:%.*]], float [[X:%.*]], float 0x7FF0000000000000
 ; CHECK-NEXT:    call void @usef32(float [[SELECT]])
-; CHECK-NEXT:    [[TMP1:%.*]] = call float @llvm.fabs.f32(float [[X]])
-; CHECK-NEXT:    [[FABS:%.*]] = select i1 [[COND]], float [[TMP1]], float 0x7FF0000000000000
+; CHECK-NEXT:    [[FABS:%.*]] = call float @llvm.fabs.f32(float [[SELECT]])
 ; CHECK-NEXT:    ret float [[FABS]]
 ;
   %select = select i1 %cond, float %x, float 0x7FF0000000000000