[llvm] [VectorUtils][VPlan] Consolidate VPWidenIntrinsicRecipe::onlyFirstLaneUsed and isVectorIntrinsicWithScalarOpAtArg (PR #137497)

[Luke Lau via llvm-commits]

================
@@ -1373,10 +1373,8 @@ StringRef VPWidenIntrinsicRecipe::getIntrinsicName() const {
 
 bool VPWidenIntrinsicRecipe::onlyFirstLaneUsed(const VPValue *Op) const {
   assert(is_contained(operands(), Op) && "Op must be an operand of the recipe");
-  // Vector predication intrinsics only demand the the first lane the last
-  // operand (the EVL operand).
-  return VPIntrinsic::isVPIntrinsic(VectorIntrinsicID) &&
-         Op == getOperand(getNumOperands() - 1);
+  unsigned Idx = std::distance(op_begin(), find(operands(), Op));
+  return isVectorIntrinsicWithScalarOpAtArg(VectorIntrinsicID, Idx, nullptr);
----------------
lukel97 wrote:

It turns out yes, I was able to add a case where we no longer broadcast and extract the scalar operand to powi. It should be precomitted in this PR now

https://github.com/llvm/llvm-project/pull/137497