[llvm] [VPlan] Directly unroll VectorPointerRecipe (PR #168886)

[Florian Hahn via llvm-commits]

================
@@ -297,6 +297,21 @@ void UnrollState::unrollRecipeByUF(VPRecipeBase &R) {
       Copy->setOperand(1, getValueForPart(Op, Part));
       continue;
     }
+    if (auto *VPR = dyn_cast<VPVectorPointerRecipe>(&R)) {
+      VPBuilder Builder(VPR);
+      const DataLayout &DL =
+          Plan.getScalarHeader()->getIRBasicBlock()->getDataLayout();
+      Type *IndexTy = DL.getIndexType(TypeInfo.inferScalarType(VPR));
+      Type *VFTy = TypeInfo.inferScalarType(&Plan.getVF());
+      VPValue *VF = Builder.createScalarZExtOrTrunc(
+          &Plan.getVF(), IndexTy, VFTy, DebugLoc::getUnknown());
+      VPValue *VFxPart = Builder.createOverflowingOp(
+          Instruction::Mul, {VF, Plan.getConstantInt(IndexTy, Part)},
+          {true, true});
----------------
fhahn wrote:

```suggestion
    // VFxUF does not wrap, so VF * Part also cannot wrap.
      VPValue *VFxPart = Builder.createOverflowingOp(
          Instruction::Mul, {VF, Plan.getConstantInt(IndexTy, Part)},
          {true, true});
```



https://github.com/llvm/llvm-project/pull/168886