[llvm] [AArch64] Lower partial add reduction to udot or svdot (PR #101010)

[Sander de Smalen via llvm-commits]

================
@@ -1971,6 +1971,57 @@ bool AArch64TargetLowering::shouldExpandGetActiveLaneMask(EVT ResVT,
   return false;
 }
 
+bool AArch64TargetLowering::shouldExpandPartialReductionIntrinsic(
+    const CallInst *CI) const {
+  const bool TargetLowers = false;
+  const bool GenericLowers = true;
+
+  auto *I = dyn_cast<IntrinsicInst>(CI);
+  if (!I)
+    return GenericLowers;
+
+  ScalableVectorType *RetTy = dyn_cast<ScalableVectorType>(I->getType());
+
+  if (!RetTy)
+    return GenericLowers;
+
+  ScalableVectorType *InputTy = nullptr;
+
+  auto RetScalarTy = RetTy->getScalarType();
+  if (RetScalarTy->isIntegerTy(64)) {
+    InputTy = ScalableVectorType::get(Type::getInt16Ty(I->getContext()), 8);
+  } else if (RetScalarTy->isIntegerTy(32)) {
+    InputTy = ScalableVectorType::get(Type::getInt8Ty(I->getContext()), 16);
+  }
+
+  if (!InputTy)
+    return GenericLowers;
----------------
sdesmalen-arm wrote:

```suggestion
  else
      return GenericLowers;
```

https://github.com/llvm/llvm-project/pull/101010