[llvm] [VPlan] Replace ExtractLast(Elem|LanePerPart) with ExtractLast(Lane/Part) (PR #164124)

[via llvm-commits]

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@@ -395,9 +395,17 @@ m_ExtractElement(const Op0_t &Op0, const Op1_t &Op1) {
 }
 
 template <typename Op0_t>
-inline VPInstruction_match<VPInstruction::ExtractLastLanePerPart, Op0_t>
-m_ExtractLastLanePerPart(const Op0_t &Op0) {
-  return m_VPInstruction<VPInstruction::ExtractLastLanePerPart>(Op0);
+inline VPInstruction_match<VPInstruction::ExtractLastPart, Op0_t>
+m_ExtractLastPart(const Op0_t &Op0) {
+  return m_VPInstruction<VPInstruction::ExtractLastPart>(Op0);
+}
+
+template <typename Op0_t>
+inline VPInstruction_match<
+    VPInstruction::ExtractLastLane,
+    VPInstruction_match<VPInstruction::ExtractLastPart, Op0_t>>
+m_ExtractLastElement(const Op0_t &Op0) {
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ayalz wrote:

```suggestion
m_ExtractFinalLane(const Op0_t &Op0) {
```
?
The term `Element` is used to represent a lane when VF>1 and otherwise a part, as in `ExtractPenultimateElement`. Perhaps `FinalLane` would be clearer to represent the last lane of the last part.

https://github.com/llvm/llvm-project/pull/164124