[llvm] [InstCombine] Add ctpop(A | B) + ctpop(A & B) -> ctpop(A) + ctpop(B) (PR #79089)

[Yingwei Zheng via llvm-commits]

================
@@ -1718,6 +1718,25 @@ Instruction *InstCombinerImpl::visitAdd(BinaryOperator &I) {
         Builder.CreateIntrinsic(Intrinsic::umax, {I.getType()}, {A, B}));
   }
 
+  // ctpop(A | B) + ctpop(A & B) -> ctpop(A) + ctpop(B)
+  if ((match(LHS, m_OneUse(m_Intrinsic<Intrinsic::ctpop>(
+                      m_And(m_Value(A), m_Value(B))))) &&
+       (match(RHS, m_OneUse(m_Intrinsic<Intrinsic::ctpop>(
+                       m_Or(m_Specific(A), m_Specific(B))))) ||
+        match(RHS, m_OneUse(m_Intrinsic<Intrinsic::ctpop>(
+                       m_Or(m_Specific(B), m_Specific(A))))))) ||
+      (match(LHS, m_OneUse(m_Intrinsic<Intrinsic::ctpop>(
+                      m_Or(m_Value(A), m_Value(B))))) &&
+       (match(RHS, m_OneUse(m_Intrinsic<Intrinsic::ctpop>(
+                       m_And(m_Specific(A), m_Specific(B))))) ||
+        match(RHS, m_OneUse(m_Intrinsic<Intrinsic::ctpop>(
+                       m_And(m_Specific(B), m_Specific(A)))))))) {
+    return replaceInstUsesWith(
+        I, Builder.CreateAdd(
+               Builder.CreateIntrinsic(Intrinsic::ctpop, {A->getType()}, {A}),
+               Builder.CreateIntrinsic(Intrinsic::ctpop, {B->getType()}, {B})));
----------------
dtcxzyw wrote:

```suggestion
    return BinaryOperator::CreateAdd(
               Builder.CreateUnaryIntrinsic(Intrinsic::ctpop, A),
               Builder.CreateUnaryIntrinsic(Intrinsic::ctpop, B));
```


https://github.com/llvm/llvm-project/pull/79089