[llvm] [VPlan] Support multiple F(Max|Min)Num reductions. (PR #161735)

[via llvm-commits]

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@@ -879,52 +867,72 @@ bool VPlanTransforms::handleMaxMinNumReductions(VPlan &Plan) {
   }
 
   VPBasicBlock *LatchVPBB = LoopRegion->getExitingBasicBlock();
+  VPBasicBlock *MiddleVPBB = Plan.getMiddleBlock();
+  VPBuilder MiddleBuilder(MiddleVPBB, MiddleVPBB->begin());
   VPBuilder Builder(LatchVPBB->getTerminator());
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ayalz wrote:

```suggestion
  VPBuilder LatchBuilder(LatchVPBB->getTerminator());
```
consistent with `MiddleBuilder`.
Can be pre-applied independently.

https://github.com/llvm/llvm-project/pull/161735