From 81b16a3558514481c61e7c68d19f84d7a69352cb Mon Sep 17 00:00:00 2001
From: Dan Gohman <gohman@apple.com>
Date: Tue, 20 Oct 2009 04:16:37 +0000
Subject: [PATCH] Add getTopBlock and getBottomBlock member functions to
 MachineLoopInfo.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@84596 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/CodeGen/MachineLoopInfo.h | 11 ++++++++++
 lib/CodeGen/MachineLoopInfo.cpp        | 28 ++++++++++++++++++++++++++
 2 files changed, 39 insertions(+)

diff --git a/include/llvm/CodeGen/MachineLoopInfo.h b/include/llvm/CodeGen/MachineLoopInfo.h
index 65ad4e48414..d3df805f642 100644
--- a/include/llvm/CodeGen/MachineLoopInfo.h
+++ b/include/llvm/CodeGen/MachineLoopInfo.h
@@ -38,6 +38,17 @@ namespace llvm {
 class MachineLoop : public LoopBase<MachineBasicBlock, MachineLoop> {
 public:
   MachineLoop();
+
+  /// getTopBlock - Return the "top" block in the loop, which is the first
+  /// block in the linear layout, ignoring any parts of the loop not
+  /// contiguous with the part the contains the header.
+  MachineBasicBlock *getTopBlock();
+
+  /// getBottomBlock - Return the "bottom" block in the loop, which is the last
+  /// block in the linear layout, ignoring any parts of the loop not
+  /// contiguous with the part the contains the header.
+  MachineBasicBlock *getBottomBlock();
+
 private:
   friend class LoopInfoBase<MachineBasicBlock, MachineLoop>;
   explicit MachineLoop(MachineBasicBlock *MBB)
diff --git a/lib/CodeGen/MachineLoopInfo.cpp b/lib/CodeGen/MachineLoopInfo.cpp
index 2da8e3760e9..db77d192ccb 100644
--- a/lib/CodeGen/MachineLoopInfo.cpp
+++ b/lib/CodeGen/MachineLoopInfo.cpp
@@ -43,3 +43,31 @@ void MachineLoopInfo::getAnalysisUsage(AnalysisUsage &AU) const {
   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 = next(MachineFunction::iterator(BotMBB));
+    while (contains(NextMBB)) {
+      BotMBB = NextMBB;
+      if (BotMBB == next(MachineFunction::iterator(BotMBB))) break;
+      NextMBB = next(MachineFunction::iterator(BotMBB));
+    }
+  }
+  return BotMBB;
+}