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

[Florian Hahn 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!");
+    VPValue2Name[V] = (Twine("vp<%") + Twine(NextSlot) + ">").str();
+    NextSlot++;
     return;
-  assert(!Slots.contains(V) && "VPValue already has a slot!");
-  Slots[V] = NextSlot++;
+  }
+  std::string Name;
+  raw_string_ostream S(Name);
+  UV->printAsOperand(S, false);
+  versionName(V, Name);
 }
 
-void VPSlotTracker::assignSlots(const VPlan &Plan) {
+void VPSlotTracker::assignSlotsOrNames(const VPlan &Plan) {
   if (Plan.VFxUF.getNumUsers() > 0)
-    assignSlot(&Plan.VFxUF);
-  assignSlot(&Plan.VectorTripCount);
+    assignSlotOrName(&Plan.VFxUF);
+  assignSlotOrName(&Plan.VectorTripCount);
   if (Plan.BackedgeTakenCount)
-    assignSlot(Plan.BackedgeTakenCount);
-  assignSlots(Plan.getPreheader());
+    assignSlotOrName(Plan.BackedgeTakenCount);
+  for (VPValue *LI : Plan.VPLiveInsToFree)
+    assignSlotOrName(LI);
+  assignSlotsOrNames(Plan.getPreheader());
 
   ReversePostOrderTraversal<VPBlockDeepTraversalWrapper<const VPBlockBase *>>
       RPOT(VPBlockDeepTraversalWrapper<const VPBlockBase *>(Plan.getEntry()));
   for (const VPBasicBlock *VPBB :
        VPBlockUtils::blocksOnly<const VPBasicBlock>(RPOT))
-    assignSlots(VPBB);
+    assignSlotsOrNames(VPBB);
 }
 
-void VPSlotTracker::assignSlots(const VPBasicBlock *VPBB) {
+void VPSlotTracker::assignSlotsOrNames(const VPBasicBlock *VPBB) {
   for (const VPRecipeBase &Recipe : *VPBB)
     for (VPValue *Def : Recipe.definedValues())
-      assignSlot(Def);
+      assignSlotOrName(Def);
+}
+
+void VPSlotTracker::versionName(const VPValue *V, StringRef Name) {
+  assert(!Name.empty() && "Name cannot be empty.");
+  std::string BaseName = (Twine("ir<") + Name + Twine(">")).str();
+
+  // First assign the base name for V.
+  const auto &[A, AssignedInserted] = VPValue2Name.insert({V, BaseName});
+  assert(AssignedInserted && "name assigned already?");
+  if (V->isLiveIn())
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fhahn wrote:

Some live-ins (integer/fp constants) will print to the same string due to the type being stripped. Clarified by only bailing out for those types + a comment

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