[llvm] [VPlan] Add VPIRBasicBlock, use to model pre-preheader. (PR #93398)

[Florian Hahn via llvm-commits]

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@@ -442,6 +442,58 @@ VPBasicBlock::createEmptyBasicBlock(VPTransformState::CFGState &CFG) {
   return NewBB;
 }
 
+void VPIRWrapperBlock::execute(VPTransformState *State) {
+  for (VPBlockBase *PredVPBlock : getHierarchicalPredecessors()) {
+    VPBasicBlock *PredVPBB = PredVPBlock->getExitingBasicBlock();
+    auto &PredVPSuccessors = PredVPBB->getHierarchicalSuccessors();
+    BasicBlock *PredBB = State->CFG.VPBB2IRBB[PredVPBB];
+
+    assert(PredBB && "Predecessor basic-block not found building successor.");
+    auto *PredBBTerminator = PredBB->getTerminator();
+    LLVM_DEBUG(dbgs() << "LV: draw edge from" << PredBB->getName() << '\n');
+
+    auto *TermBr = dyn_cast<BranchInst>(PredBBTerminator);
+    if (TermBr) {
+      // Set each forward successor here when it is created, excluding
+      // backedges. A backward successor is set when the branch is created.
+      unsigned idx = PredVPSuccessors.front() == this ? 0 : 1;
+      assert(!TermBr->getSuccessor(idx) &&
+             "Trying to reset an existing successor block.");
+      TermBr->setSuccessor(idx, WrappedBlock);
+    }
+  }
+
+  assert(getHierarchicalSuccessors().size() == 0 &&
+         "VPIRWrapperBlock cannot have successors");
+  State->CFG.VPBB2IRBB[this] = getWrappedBlock();
+  State->CFG.PrevVPBB = this;
+
+  auto *Term = cast<BranchInst>(getWrappedBlock()->getTerminator());
+  State->Builder.SetInsertPoint(Term);
+
+  for (VPRecipeBase &Recipe : *this)
+    Recipe.execute(*State);
+
+  LLVM_DEBUG(dbgs() << "LV: filled BB:" << *getWrappedBlock());
+}
+
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
+
+void VPIRWrapperBlock::print(raw_ostream &O, const Twine &Indent,
+                             VPSlotTracker &SlotTracker) const {
+  O << Indent << "ir-bb<" << getName() << ">:\n";
+
+  auto RecipeIndent = Indent + "  ";
+  for (const VPRecipeBase &Recipe : *this) {
+    Recipe.print(O, RecipeIndent, SlotTracker);
+    O << '\n';
+  }
+  assert(getSuccessors().empty() &&
+         "Wrapper blocks should not have successors");
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fhahn wrote:

Print implementation is gone now

https://github.com/llvm/llvm-project/pull/93398