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

[Florian Hahn via llvm-commits]

================
@@ -4158,6 +4170,26 @@ tryToMatchAndCreateMulAccumulateReduction(VPReductionRecipe *Red,
   VPRecipeBase *Sub = nullptr;
   VPValue *A, *B;
   VPValue *Tmp = nullptr;
+
+  // Try to match reduce.fadd(fmul(...)).
+  if (match(VecOp, m_FMul(m_VPValue(A), m_VPValue(B)))) {
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fhahn wrote:

clearer to match the full expression at the outset?

```suggestion
  if (match(VecOp, m_FMul(m_FPExt(m_VPValue()), m_FPExt (m_VPValue()))) {
```

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