[llvm] [LoopVectorizer] Add support for partial reductions (PR #92418)

[Sam Tebbs via llvm-commits]

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@@ -341,6 +341,15 @@ class AArch64TTIImpl : public BasicTTIImplBase<AArch64TTIImpl> {
     return BaseT::isLegalNTLoad(DataType, Alignment);
   }
 
+  bool isPartialReductionSupported(const Instruction *ReductionInstr,
+                                   Type *InputType, unsigned ScaleFactor,
+                                   bool IsInputASignExtended,
+                                   bool IsInputBSignExtended,
+                                   const Instruction *BinOp) const {
+    return ScaleFactor == 4 && (ST->isSVEorStreamingSVEAvailable() ||
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SamTebbs33 wrote:

Done. Let me know if I've missed anything.

https://github.com/llvm/llvm-project/pull/92418