1 files changed, 78 insertions, 0 deletions
diff --git a/llvm/lib/CodeGen/MachinePostDominators.cpp b/llvm/lib/CodeGen/MachinePostDominators.cpp
new file mode 100644
index 000000000000..f4daff667e86
--- /dev/null
+++ b/llvm/lib/CodeGen/MachinePostDominators.cpp
@@ -0,0 +1,78 @@
+//===- MachinePostDominators.cpp -Machine Post Dominator Calculation ------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements simple dominator construction algorithms for finding
+// post dominators on machine functions.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CodeGen/MachinePostDominators.h"
+
+using namespace llvm;
+
+namespace llvm {
+template class DominatorTreeBase<MachineBasicBlock, true>; // PostDomTreeBase
+
+extern bool VerifyMachineDomInfo;
+} // namespace llvm
+
+char MachinePostDominatorTree::ID = 0;
+
+//declare initializeMachinePostDominatorTreePass
+INITIALIZE_PASS(MachinePostDominatorTree, "machinepostdomtree",
+                "MachinePostDominator Tree Construction", true, true)
+
+MachinePostDominatorTree::MachinePostDominatorTree()
+    : MachineFunctionPass(ID), PDT(nullptr) {
+  initializeMachinePostDominatorTreePass(*PassRegistry::getPassRegistry());
+}
+
+FunctionPass *MachinePostDominatorTree::createMachinePostDominatorTreePass() {
+  return new MachinePostDominatorTree();
+}
+
+bool MachinePostDominatorTree::runOnMachineFunction(MachineFunction &F) {
+  PDT = std::make_unique<PostDomTreeT>();
+  PDT->recalculate(F);
+  return false;
+}
+
+void MachinePostDominatorTree::getAnalysisUsage(AnalysisUsage &AU) const {
+  AU.setPreservesAll();
+  MachineFunctionPass::getAnalysisUsage(AU);
+}
+
+MachineBasicBlock *MachinePostDominatorTree::findNearestCommonDominator(
+    ArrayRef<MachineBasicBlock *> Blocks) const {
+  assert(!Blocks.empty());
+
+  MachineBasicBlock *NCD = Blocks.front();
+  for (MachineBasicBlock *BB : Blocks.drop_front()) {
+    NCD = PDT->findNearestCommonDominator(NCD, BB);
+
+    // Stop when the root is reached.
+    if (PDT->isVirtualRoot(PDT->getNode(NCD)))
+      return nullptr;
+  }
+
+  return NCD;
+}
+
+void MachinePostDominatorTree::verifyAnalysis() const {
+  if (PDT && VerifyMachineDomInfo)
+    if (!PDT->verify(PostDomTreeT::VerificationLevel::Basic)) {
+      errs() << "MachinePostDominatorTree verification failed\n";
+
+      abort();
+    }
+}
+
+void MachinePostDominatorTree::print(llvm::raw_ostream &OS,
+                                     const Module *M) const {
+  PDT->print(OS);
+}