Add MachineLoopInfo. This is not yet tested.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@44384 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/MachineLoopInfo.cpp

@@ -0,0 +1,41 @@
+//===- MachineLoopInfo.cpp - Natural Loop Calculator ----------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by Owen Anderson and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the MachineLoopInfo class that is used to identify natural
+// loops and determine the loop depth of various nodes of the CFG.  Note that
+// the loops identified may actually be several natural loops that share the 
+// same header node... not just a single natural loop.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CodeGen/MachineLoopInfo.h"
+#include "llvm/CodeGen/MachineDominators.h"
+
+using namespace llvm;
+
+TEMPLATE_INSTANTIATION(class LoopBase<MachineBasicBlock>);
+TEMPLATE_INSTANTIATION(class LoopInfoBase<MachineBasicBlock>);
+
+char MachineLoopInfo::ID = 0;
+static RegisterPass<MachineLoopInfo>
+X("machine-loops", "Machine Natural Loop Construction", true);
+
+bool MachineLoopInfo::runOnMachineFunction(MachineFunction &) {
+  releaseMemory();
+  LI->Calculate(getAnalysis<MachineDominatorTree>().getBase());    // Update
+  return false;
+}
+
+void MachineLoopInfo::getAnalysisUsage(AnalysisUsage &AU) const {
+  AU.setPreservesAll();
+  AU.addRequired<MachineDominatorTree>();
+}
+
+// Ensure this file gets linked when MachineLoopInfo.h is used.
+DEFINING_FILE_FOR(MachineLoopInfo)