[InstCombine] Fix FMF propagation in copysign Mag, (copysign ?, X) -> copysign Mag, X

Author: dtcxzyw

llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp

@@ -2673,8 +2673,10 @@ Instruction *InstCombinerImpl::visitCallInst(CallInst &CI) {
     // Propagate sign argument through nested calls:
     // copysign Mag, (copysign ?, X) --> copysign Mag, X
     Value *X;
-    if (match(Sign, m_Intrinsic<Intrinsic::copysign>(m_Value(), m_Value(X))))
+    if (match(Sign, m_Intrinsic<Intrinsic::copysign>(m_Value(), m_Value(X)))) {
+      II->andIRFlags(Sign);
       return replaceOperand(*II, 1, X);
+    }
 
     // Clear sign-bit of constant magnitude:
     // copysign -MagC, X --> copysign MagC, X

llvm/test/Transforms/InstCombine/copysign.ll

@@ -82,7 +82,7 @@ define float @not_known_positive_sign_arg(float %x, float %y) {
 
 define float @copysign_sign_arg(float %x, float %y, float %z) {
 ; CHECK-LABEL: @copysign_sign_arg(
-; CHECK-NEXT:    [[R:%.*]] = call ninf float @llvm.copysign.f32(float [[X:%.*]], float [[Z:%.*]])
+; CHECK-NEXT:    [[R:%.*]] = call float @llvm.copysign.f32(float [[X:%.*]], float [[Z:%.*]])
 ; CHECK-NEXT:    ret float [[R]]
 ;
   %s = call reassoc float @llvm.copysign.f32(float %y, float %z)