Separate LoopTraversal, ReachingDefAnalysis and BreakFalseDeps into their own files.

This is the one of multiple patches that fix bugzilla https://bugs.llvm.org/show_bug.cgi?id=33869
Most of the patches are intended at refactoring the existent code.

Additional relevant reviews:
https://reviews.llvm.org/D40330
https://reviews.llvm.org/D40331
https://reviews.llvm.org/D40332
https://reviews.llvm.org/D40334

Differential Revision: https://reviews.llvm.org/D40333

Change-Id: Ie5f8eb34d98cfdfae23a3072eb69b5794f0e2d56
llvm-svn: 323095

1 files changed, 77 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/LoopTraversal.cpp b/llvm/lib/CodeGen/LoopTraversal.cpp
new file mode 100644
index 00000000000..7b7e0ee13bc
--- /dev/null
+++ b/llvm/lib/CodeGen/LoopTraversal.cpp
@@ -0,0 +1,77 @@
+//===- LoopTraversal.cpp - Optimal basic block traversal order --*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CodeGen/LoopTraversal.h"
+#include "llvm/ADT/PostOrderIterator.h"
+#include "llvm/CodeGen/MachineFunction.h"
+
+using namespace llvm;
+
+bool LoopTraversal::isBlockDone(MachineBasicBlock *MBB) {
+  int MBBNumber = MBB->getNumber();
+  assert(MBBNumber < MBBInfos.size() && "Unexpected basic block number.");
+  return MBBInfos[MBBNumber].PrimaryCompleted &&
+         MBBInfos[MBBNumber].IncomingCompleted ==
+             MBBInfos[MBBNumber].PrimaryIncoming &&
+         MBBInfos[MBBNumber].IncomingProcessed == MBB->pred_size();
+}
+
+LoopTraversal::TraversalOrder LoopTraversal::traverse(MachineFunction &MF) {
+  // Initialize the MMBInfos
+  MBBInfos.assign(MF.getNumBlockIDs(), MBBInfo());
+
+  MachineBasicBlock *Entry = &*MF.begin();
+  ReversePostOrderTraversal<MachineBasicBlock *> RPOT(Entry);
+  SmallVector<MachineBasicBlock *, 4> Workqueue;
+  SmallVector<TraversedMBBInfo, 4> MBBTraversalOrder;
+  for (MachineBasicBlock *MBB : RPOT) {
+    // N.B: IncomingProcessed and IncomingCompleted were already updated while
+    // processing this block's predecessors.
+    int MBBNumber = MBB->getNumber();
+    assert(MBBNumber < MBBInfos.size() && "Unexpected basic block number.");
+    MBBInfos[MBBNumber].PrimaryCompleted = true;
+    MBBInfos[MBBNumber].PrimaryIncoming = MBBInfos[MBBNumber].IncomingProcessed;
+    bool Primary = true;
+    Workqueue.push_back(MBB);
+    while (!Workqueue.empty()) {
+      MachineBasicBlock *ActiveMBB = &*Workqueue.back();
+      Workqueue.pop_back();
+      bool Done = isBlockDone(ActiveMBB);
+      MBBTraversalOrder.push_back(TraversedMBBInfo(ActiveMBB, Primary, Done));
+      for (MachineBasicBlock *Succ : ActiveMBB->successors()) {
+        int SuccNumber = Succ->getNumber();
+        assert(SuccNumber < MBBInfos.size() &&
+               "Unexpected basic block number.");
+        if (!isBlockDone(Succ)) {
+          if (Primary)
+            MBBInfos[SuccNumber].IncomingProcessed++;
+          if (Done)
+            MBBInfos[SuccNumber].IncomingCompleted++;
+          if (isBlockDone(Succ))
+            Workqueue.push_back(Succ);
+        }
+      }
+      Primary = false;
+    }
+  }
+
+  // We need to go through again and finalize any blocks that are not done yet.
+  // This is possible if blocks have dead predecessors, so we didn't visit them
+  // above.
+  for (MachineBasicBlock *MBB : RPOT) {
+    if (!isBlockDone(MBB))
+      MBBTraversalOrder.push_back(TraversedMBBInfo(MBB, false, true));
+    // Don't update successors here. We'll get to them anyway through this
+    // loop.
+  }
+
+  MBBInfos.clear();
+
+  return MBBTraversalOrder;
+}