[llvm] [VPlan] Implement interleaving as VPlan-to-VPlan transform. (PR #95842)

[via llvm-commits]

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@@ -1569,3 +1569,379 @@ void VPlanTransforms::dropPoisonGeneratingRecipes(
     }
   }
 }
+
+namespace {
+class InterleaveState {
+  DenseMap<VPValue *, SmallVector<VPValue *>> InterleavedValues;
+
+public:
+  VPValue *getInterleavedValue(VPValue *V, unsigned IC) {
+    if (IC == 0)
+      return V;
+    if (V->isLiveIn())
+      return V;
+    return InterleavedValues[V][IC - 1];
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ayalz wrote:

Assert value exists?

https://github.com/llvm/llvm-project/pull/95842