MIsched: Improve the interface to SchedDFS analysis (subtrees).

Allow the strategy to select SchedDFS. Allow the results of SchedDFS
to affect initialization of the scheduler state.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@173425 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 12 insertions, 9 deletions

diff --git a/include/llvm/CodeGen/MachineScheduler.h b/include/llvm/CodeGen/MachineScheduler.h
index cc697a50ab..aa78f5285a 100644
--- a/include/llvm/CodeGen/MachineScheduler.h
+++ b/include/llvm/CodeGen/MachineScheduler.h
@@ -316,12 +316,9 @@ public:
 
   const SUnit *getNextClusterSucc() const { return NextClusterSucc; }
 
-  /// Initialize a DFSResult after DAG building is complete, and before any
+  /// Compute a DFSResult after DAG building is complete, and before any
   /// queue comparisons.
-  void initDFSResult();
-
-  /// Compute DFS result once all interesting roots are discovered.
-  void computeDFSResult(ArrayRef<SUnit*> Roots);
+  void computeDFSResult();
 
   /// Return a non-null DFS result if the scheduling strategy initialized it.
   const SchedDFSResult *getDFSResult() const { return DFSResult; }
@@ -341,8 +338,8 @@ protected:
   /// instances of ScheduleDAGMI to perform custom DAG postprocessing.
   void postprocessDAG();
 
-  /// Identify DAG roots and setup scheduler queues.
-  void initQueues();
+  /// Release ExitSU predecessors and setup scheduler queues.
+  void initQueues(ArrayRef<SUnit*> TopRoots, ArrayRef<SUnit*> BotRoots);
 
   /// Move an instruction and update register pressure.
   void scheduleMI(SUnit *SU, bool IsTopNode);
@@ -365,7 +362,8 @@ protected:
   void moveInstruction(MachineInstr *MI, MachineBasicBlock::iterator InsertPos);
   bool checkSchedLimit();
 
-  void releaseRoots();
+  void findRootsAndBiasEdges(SmallVectorImpl<SUnit*> &TopRoots,
+                             SmallVectorImpl<SUnit*> &BotRoots);
 
   void releaseSucc(SUnit *SU, SDep *SuccEdge);
   void releaseSuccessors(SUnit *SU);
diff --git a/include/llvm/CodeGen/ScheduleDFS.h b/include/llvm/CodeGen/ScheduleDFS.h
index 54b223269e..e07929290e 100644
--- a/include/llvm/CodeGen/ScheduleDFS.h
+++ b/include/llvm/CodeGen/ScheduleDFS.h
@@ -127,7 +127,7 @@ public:
   }
 
   /// \brief Compute various metrics for the DAG with given roots.
-  void compute(ArrayRef<SUnit *> Roots);
+  void compute(ArrayRef<SUnit> SUnits);
 
   /// \brief Get the ILP value for a DAG node.
   ///
@@ -140,7 +140,12 @@ public:
   unsigned getNumSubtrees() const { return SubtreeConnectLevels.size(); }
 
   /// \brief Get the ID of the subtree the given DAG node belongs to.
+  ///
+  /// For convenience, if DFSResults have not been computed yet, give everything
+  /// tree ID 0.
   unsigned getSubtreeID(const SUnit *SU) const {
+    if (empty())
+      return 0;
     assert(SU->NodeNum < DFSData.size() &&  "New Node");
     return DFSData[SU->NodeNum].SubtreeID;
   }