[lld] [flang] [llvm] [lldb] [clang-tools-extra] [clang] [libc] [compiler-rt] [libcxx] [VPlan] Implement cloning of VPlans. (PR #73158)

[Florian Hahn via cfe-commits]

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@@ -982,6 +994,65 @@ void VPlan::updateDominatorTree(DominatorTree *DT, BasicBlock *LoopHeaderBB,
   assert(DT->verify(DominatorTree::VerificationLevel::Fast));
 }
 
+static void remapVPValues(VPBasicBlock *OldBB, VPBasicBlock *NewBB,
+                          DenseMap<VPValue *, VPValue *> &Old2NewVPValues,
+                          bool Full = false) {
+  for (const auto &[OldR, NewR] : zip(*OldBB, *NewBB)) {
+    for (unsigned I = 0, E = NewR.getNumOperands(); I != E; ++I) {
+      VPValue *NewOp = Old2NewVPValues.lookup(OldR.getOperand(I));
+      if (!Full)
+        continue;
+      NewR.setOperand(I, NewOp);
+    }
+    for (const auto &[OldV, NewV] :
+         zip(OldR.definedValues(), NewR.definedValues()))
+      Old2NewVPValues[OldV] = NewV;
+  }
+}
+
+VPlan *VPlan::clone() {
+  DenseMap<VPBlockBase *, VPBlockBase *> Old2New;
+  DenseMap<VPValue *, VPValue *> Old2NewVPValues;
+
+  auto *NewPlan = new VPlan();
+  SmallVector<VPValue *, 16> NewLiveIns;
+  for (VPValue *LI : VPLiveInsToFree) {
+    VPValue *NewLI = new VPValue(LI->getLiveInIRValue());
+    NewPlan->VPLiveInsToFree.push_back(NewLI);
+    Old2NewVPValues[LI] = NewLI;
+  }
+
+  Old2NewVPValues[&VectorTripCount] = &NewPlan->VectorTripCount;
+  Old2NewVPValues[&VFxUF] = &NewPlan->VFxUF;
+  if (BackedgeTakenCount) {
+    Old2NewVPValues[BackedgeTakenCount] = new VPValue();
+    NewPlan->BackedgeTakenCount = Old2NewVPValues[BackedgeTakenCount];
+  }
+
+  auto NewPH = cast<VPBasicBlock>(Preheader->clone());
+  remapVPValues(cast<VPBasicBlock>(Preheader), cast<VPBasicBlock>(NewPH),
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fhahn wrote:

Replace with `remapOperands`, no casts allowed, adjusted ordering as well

https://github.com/llvm/llvm-project/pull/73158