Add a MachinePostDominator pass

This is used in the AMDIL and R600 backends.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@164029 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/MachinePostDominators.cpp

@@ -0,0 +1,55 @@
+//===- MachinePostDominators.cpp -Machine Post Dominator Calculation ------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements simple dominator construction algorithms for finding
+// post dominators on machine functions.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CodeGen/MachinePostDominators.h"
+
+using namespace llvm;
+
+char MachinePostDominatorTree::ID = 0;
+
+//declare initializeMachinePostDominatorTreePass
+INITIALIZE_PASS(MachinePostDominatorTree, "machinepostdomtree",
+                "MachinePostDominator Tree Construction", true, true)
+
+MachinePostDominatorTree::MachinePostDominatorTree() : MachineFunctionPass(ID) {
+  initializeMachinePostDominatorTreePass(*PassRegistry::getPassRegistry());
+  DT = new DominatorTreeBase<MachineBasicBlock>(true); //true indicate
+                                                       // postdominator
+}
+
+FunctionPass *
+MachinePostDominatorTree::createMachinePostDominatorTreePass() {
+  return new MachinePostDominatorTree();
+}
+
+bool
+MachinePostDominatorTree::runOnMachineFunction(MachineFunction &F) {
+  DT->recalculate(F);
+  return false;
+}
+
+MachinePostDominatorTree::~MachinePostDominatorTree() {
+  delete DT;
+}
+
+void
+MachinePostDominatorTree::getAnalysisUsage(AnalysisUsage &AU) const {
+  AU.setPreservesAll();
+  MachineFunctionPass::getAnalysisUsage(AU);
+}
+
+void
+MachinePostDominatorTree::print(llvm::raw_ostream &OS, const Module *M) const {
+  DT->print(OS);
+}