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

[Florian Hahn via cfe-commits]

================
@@ -1200,6 +1271,59 @@ void VPUser::printOperands(raw_ostream &O, VPSlotTracker &SlotTracker) const {
 }
 #endif
 
+VPBlockBase *VPBlockUtils::cloneCFG(
+    VPBlockBase *Entry, DenseMap<VPBlockBase *, VPBlockBase *> &Old2New,
+    DenseMap<VPValue *, VPValue *> &Old2NewVPValues, bool FullRemapping) {
+  ReversePostOrderTraversal<VPBlockShallowTraversalWrapper<VPBlockBase *>> RPOT(
+      Entry);
+  VPBlockBase *NewEntry = nullptr;
+  for (VPBlockBase *BB : RPOT) {
+    VPBlockBase *NewBB = BB->clone();
+    if (!NewEntry)
+      NewEntry = NewBB;
+
+    for (VPBlockBase *Pred : BB->getPredecessors())
+      connectBlocks(Old2New[Pred], NewBB);
+
+    Old2New[BB] = NewBB;
+
+    if (!isa<VPBasicBlock>(BB))
+      continue;
+  }
+
+  // Update the operands of all cloned recipes starting at NewEntry. This
+  // traverses all reachable blocks. This is done in two steps, to handle cycles
+  // in PHI recipes.
+  ReversePostOrderTraversal<VPBlockDeepTraversalWrapper<VPBlockBase *>>
+      OldDeepRPOT(Entry);
+  ReversePostOrderTraversal<VPBlockDeepTraversalWrapper<VPBlockBase *>>
+      NewDeepRPOT(NewEntry);
+  // First, collect all mappings from old to new VPValues defined by cloned
+  // recipes.
+  for (const auto &[OldBB, NewBB] :
+       zip(VPBlockUtils::blocksOnly<VPBasicBlock>(OldDeepRPOT),
+           VPBlockUtils::blocksOnly<VPBasicBlock>(NewDeepRPOT))) {
+    for (const auto &[OldR, NewR] : zip(*OldBB, *NewBB))
+      for (const auto &[OldV, NewV] :
+           zip(OldR.definedValues(), NewR.definedValues()))
+        Old2NewVPValues[OldV] = NewV;
+  }
+
+  // Update all operands to use cloned VPValues.
+  for (VPBasicBlock *NewBB :
+       VPBlockUtils::blocksOnly<VPBasicBlock>(NewDeepRPOT)) {
+    for (VPRecipeBase &NewR : *NewBB)
+      for (unsigned I = 0, E = NewR.getNumOperands(); I != E; ++I) {
+        VPValue *NewOp = Old2NewVPValues.lookup(NewR.getOperand(I));
+        if (!FullRemapping)
----------------
fhahn wrote:

FullRemapping is gone

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