[llvm] Add LoopVectorizer support for `llvm.vector.partial.reduce.fadd` (PR #163975)

[Damian Heaton via llvm-commits]

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@@ -8249,7 +8250,10 @@ VPRecipeBuilder::tryToCreatePartialReduction(VPInstruction *Reduction,
          "all accumulators in chain must have same scale factor");
 
   unsigned ReductionOpcode = Reduction->getOpcode();
+
   auto *ReductionI = Reduction->getUnderlyingInstr();
+  if (ReductionOpcode == Instruction::FAdd && !ReductionI->hasAllowReassoc())
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dheaton-arm wrote:

Currently, yes. I might have missed a better place to put this, so where would you have expected the reduction to be rejected?

https://github.com/llvm/llvm-project/pull/163975