[llvm] [AArch64][SelectionDAG] Fix UDOT regression (PR #144907)

[David Sherwood via llvm-commits]

================
@@ -16865,14 +16865,13 @@ bool AArch64TargetLowering::optimizeExtendOrTruncateConversion(
     if (SrcWidth * 4 <= DstWidth) {
       if (all_of(I->users(), [&](auto *U) {
             auto *SingleUser = cast<Instruction>(&*U);
-            return (
-                match(SingleUser, m_c_Mul(m_Specific(I), m_SExt(m_Value()))) ||
-                (match(SingleUser,
-                       m_Intrinsic<
-                           Intrinsic::experimental_vector_partial_reduce_add>(
-                           m_Value(), m_Specific(I))) &&
-                 !shouldExpandPartialReductionIntrinsic(
-                     cast<IntrinsicInst>(SingleUser))));
+            bool IsMul =
----------------
david-arm wrote:

nit: Right now we no longer return early if `IsMul` is true, but I understand the code looks more readable now. If your intention is to reduce the level of indentation and split the if statements out to be more readable, what about

```
  if (match(SingleUser, m_c_Mul(m_Specific(I), m_SExt(m_Value()))))
    return true;
  if (match(SingleUser,
            m_Intrinsic<Intrinsic::experimental_vector_partial_reduce_add>(
            m_Value(), m_Specific(I))))
    return true;
  return false;
```

? If you prefer the original version that's also fine!

https://github.com/llvm/llvm-project/pull/144907