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

[via cfe-commits]

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@@ -982,6 +1037,92 @@ void VPlan::updateDominatorTree(DominatorTree *DT, BasicBlock *LoopHeaderBB,
   assert(DT->verify(DominatorTree::VerificationLevel::Fast));
 }
 
+static void remapOperands(VPBlockBase *Entry, VPBlockBase *NewEntry,
+                          DenseMap<VPValue *, VPValue *> &Old2NewVPValues) {
+  // 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))) {
+    assert(OldBB->getRecipeList().size() == NewBB->getRecipeList().size() &&
+           "blocks must have the same number of recipes");
+
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ayalz wrote:

nit: empty line intentional?

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