[llvm] [VPlan] Version VPValue names in VPSlotTracker. (PR #81411)

[via llvm-commits]

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@@ -1373,32 +1362,84 @@ VPInterleavedAccessInfo::VPInterleavedAccessInfo(VPlan &Plan,
   visitRegion(Plan.getVectorLoopRegion(), Old2New, IAI);
 }
 
-void VPSlotTracker::assignSlot(const VPValue *V) {
-  if (V->getUnderlyingValue())
+void VPSlotTracker::assignSlotOrName(const VPValue *V) {
+  auto *UV = V->getUnderlyingValue();
+  if (!UV) {
+    assert(!VPValue2Name.contains(V) && "VPValue already has a slot!");
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ayalz wrote:

```suggestion
  assert(!VPValue2Name.contains(V) && "VPValue already has a name!");
  auto *UV = V->getUnderlyingValue();
  if (!UV) {
```

https://github.com/llvm/llvm-project/pull/81411