Check in LLVM r95781.
diff --git a/lib/CodeGen/MachineLoopInfo.cpp b/lib/CodeGen/MachineLoopInfo.cpp
new file mode 100644
index 0000000..269538b
--- /dev/null
+++ b/lib/CodeGen/MachineLoopInfo.cpp
@@ -0,0 +1,80 @@
+//===- MachineLoopInfo.cpp - Natural Loop Calculator ----------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file 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"
+#include "llvm/CodeGen/Passes.h"
+#include "llvm/Support/Debug.h"
+using namespace llvm;
+
+namespace llvm {
+#define MLB class LoopBase<MachineBasicBlock, MachineLoop>
+TEMPLATE_INSTANTIATION(MLB);
+#undef MLB
+#define MLIB class LoopInfoBase<MachineBasicBlock, MachineLoop>
+TEMPLATE_INSTANTIATION(MLIB);
+#undef MLIB
+}
+
+char MachineLoopInfo::ID = 0;
+static RegisterPass<MachineLoopInfo>
+X("machine-loops", "Machine Natural Loop Construction", true);
+
+const PassInfo *const llvm::MachineLoopInfoID = &X;
+
+bool MachineLoopInfo::runOnMachineFunction(MachineFunction &) {
+ releaseMemory();
+ LI.Calculate(getAnalysis<MachineDominatorTree>().getBase()); // Update
+ return false;
+}
+
+void MachineLoopInfo::getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.setPreservesAll();
+ AU.addRequired<MachineDominatorTree>();
+ MachineFunctionPass::getAnalysisUsage(AU);
+}
+
+MachineBasicBlock *MachineLoop::getTopBlock() {
+ MachineBasicBlock *TopMBB = getHeader();
+ MachineFunction::iterator Begin = TopMBB->getParent()->begin();
+ if (TopMBB != Begin) {
+ MachineBasicBlock *PriorMBB = prior(MachineFunction::iterator(TopMBB));
+ while (contains(PriorMBB)) {
+ TopMBB = PriorMBB;
+ if (TopMBB == Begin) break;
+ PriorMBB = prior(MachineFunction::iterator(TopMBB));
+ }
+ }
+ return TopMBB;
+}
+
+MachineBasicBlock *MachineLoop::getBottomBlock() {
+ MachineBasicBlock *BotMBB = getHeader();
+ MachineFunction::iterator End = BotMBB->getParent()->end();
+ if (BotMBB != prior(End)) {
+ MachineBasicBlock *NextMBB = llvm::next(MachineFunction::iterator(BotMBB));
+ while (contains(NextMBB)) {
+ BotMBB = NextMBB;
+ if (BotMBB == llvm::next(MachineFunction::iterator(BotMBB))) break;
+ NextMBB = llvm::next(MachineFunction::iterator(BotMBB));
+ }
+ }
+ return BotMBB;
+}
+
+void MachineLoop::dump() const {
+ print(dbgs());
+}