[llvm] [VPlan] Introduce VPlanConstantFolder (PR #125365)

[Florian Hahn via llvm-commits]

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@@ -2161,7 +2168,9 @@ void VPlanTransforms::dropPoisonGeneratingRecipes(
         // where the operands are disjoint or poison otherwise.
         if (match(RecWithFlags, m_BinaryOr(m_VPValue(A), m_VPValue(B))) &&
             RecWithFlags->isDisjoint()) {
-          VPBuilder Builder(RecWithFlags);
+          const DataLayout &DL =
+              RecWithFlags->getUnderlyingInstr()->getDataLayout();
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fhahn wrote:

Actually, it might simplify things if we first start with using the constant-folder just in `simplifyRecipe`? There it would also have much wider scope in the future, could also support `VPWidenRecipe` and others that have applicable opcodes.

https://github.com/llvm/llvm-project/pull/125365