[llvm] [VPlan] Add VPInstruction to unpack vector values to scalars. (PR #155670)

[Florian Hahn via llvm-commits]

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@@ -3789,6 +3796,42 @@ void VPlanTransforms::materializeBuildVectors(VPlan &Plan) {
           });
     }
   }
+
+  // Create explicit VPInstructions to convert vectors to scalars.
+  for (VPBasicBlock *VPBB : VPBBsInsideLoopRegion) {
+    for (VPRecipeBase &R : make_early_inc_range(*VPBB)) {
+      if (isa<VPReplicateRecipe, VPInstruction, VPScalarIVStepsRecipe>(&R))
+        continue;
+      for (VPValue *Def : R.definedValues()) {
+        if (vputils::isSingleScalar(Def) || vputils::onlyFirstLaneUsed(Def))
+          continue;
+
+        auto IsInsideReplicateRegion = [LoopRegion](VPUser *U) {
+          VPRegionBlock *ParentRegion =
+              cast<VPRecipeBase>(U)->getParent()->getParent();
+          return ParentRegion && ParentRegion != LoopRegion;
+        };
+        // At the moment, we only create unpacks for scalar users outside
+        // replicate regions. Recipes inside replicate regions still manually
+        // extract the required lanes. TODO: Remove once replicate regions are
+        // unrolled explicitly.
+        if (none_of(Def->users(), [Def, &IsInsideReplicateRegion](VPUser *U) {
+              return !IsInsideReplicateRegion(U) && U->usesScalars(Def);
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fhahn wrote:

done thanks

https://github.com/llvm/llvm-project/pull/155670