1 files changed, 30 insertions, 19 deletions

diff --git a/include/llvm/CodeGen/PostRAHazardRecognizer.h b/include/llvm/CodeGen/ScoreboardHazardRecognizer.h
index ec8d93deb7b..561bf0fecf6 100644
--- a/include/llvm/CodeGen/PostRAHazardRecognizer.h
+++ b/include/llvm/CodeGen/ScoreboardHazardRecognizer.h
@@ -1,4 +1,4 @@
-//=- llvm/CodeGen/PostRAHazardRecognizer.h - Scheduling Support -*- C++ -*-=//
+//=- llvm/CodeGen/ScoreboardHazardRecognizer.h - Schedule Support -*- C++ -*-=//
 //
 //                     The LLVM Compiler Infrastructure
 //
@@ -7,14 +7,14 @@
 //
 //===----------------------------------------------------------------------===//
 //
-// This file implements the PostRAHazardRecognizer class, which
-// implements hazard-avoidance heuristics for scheduling, based on the
+// This file defines the ScoreboardHazardRecognizer class, which
+// encapsulates hazard-avoidance heuristics for scheduling, based on the
 // scheduling itineraries specified for the target.
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef LLVM_CODEGEN_EXACTHAZARDRECOGNIZER_H
-#define LLVM_CODEGEN_EXACTHAZARDRECOGNIZER_H
+#ifndef LLVM_CODEGEN_SCOREBOARDHAZARDRECOGNIZER_H
+#define LLVM_CODEGEN_SCOREBOARDHAZARDRECOGNIZER_H
 
 #include "llvm/CodeGen/ScheduleHazardRecognizer.h"
 #include "llvm/Support/DataTypes.h"
@@ -28,13 +28,17 @@ namespace llvm {
 class InstrItineraryData;
 class SUnit;
 
-class PostRAHazardRecognizer : public ScheduleHazardRecognizer {
-  // ScoreBoard to track function unit usage. ScoreBoard[0] is a
+class ScoreboardHazardRecognizer : public ScheduleHazardRecognizer {
+  // Scoreboard to track function unit usage. Scoreboard[0] is a
   // mask of the FUs in use in the cycle currently being
-  // schedule. ScoreBoard[1] is a mask for the next cycle. The
-  // ScoreBoard is used as a circular buffer with the current cycle
+  // schedule. Scoreboard[1] is a mask for the next cycle. The
+  // Scoreboard is used as a circular buffer with the current cycle
   // indicated by Head.
-  class ScoreBoard {
+  //
+  // Scoreboard always counts cycles in forward execution order. If used by a
+  // bottom-up scheduler, then the scoreboard cycles are the inverse of the
+  // scheduler's cycles.
+  class Scoreboard {
     unsigned *Data;
 
     // The maximum number of cycles monitored by the Scoreboard. This
@@ -44,16 +48,18 @@ class PostRAHazardRecognizer : public ScheduleHazardRecognizer {
     // Indices into the Scoreboard that represent the current cycle.
     size_t Head;
   public:
-    ScoreBoard():Data(NULL), Depth(0), Head(0) { }
-    ~ScoreBoard() {
+    Scoreboard():Data(NULL), Depth(0), Head(0) { }
+    ~Scoreboard() {
       delete[] Data;
     }
 
     size_t getDepth() const { return Depth; }
     unsigned& operator[](size_t idx) const {
-      assert(Depth && "ScoreBoard was not initialized properly!");
+      // Depth is expected to be a power-of-2.
+      assert(Depth && !(Depth & (Depth - 1)) &&
+             "Scoreboard was not initialized properly!");
 
-      return Data[(Head + idx) % Depth];
+      return Data[(Head + idx) & (Depth-1)];
     }
 
     void reset(size_t d = 1) {
@@ -67,7 +73,11 @@ class PostRAHazardRecognizer : public ScheduleHazardRecognizer {
     }
 
     void advance() {
-      Head = (Head + 1) % Depth;
+      Head = (Head + 1) & (Depth-1);
+    }
+
+    void recede() {
+      Head = (Head - 1) & (Depth-1);
     }
 
     // Print the scoreboard.
@@ -77,18 +87,19 @@ class PostRAHazardRecognizer : public ScheduleHazardRecognizer {
   // Itinerary data for the target.
   const InstrItineraryData *ItinData;
 
-  ScoreBoard ReservedScoreboard;
-  ScoreBoard RequiredScoreboard;
+  Scoreboard ReservedScoreboard;
+  Scoreboard RequiredScoreboard;
 
 public:
-  PostRAHazardRecognizer(const InstrItineraryData *ItinData);
+  ScoreboardHazardRecognizer(const InstrItineraryData *ItinData);
 
   virtual HazardType getHazardType(SUnit *SU);
   virtual void Reset();
   virtual void EmitInstruction(SUnit *SU);
   virtual void AdvanceCycle();
+  virtual void RecedeCycle();
 };
 
 }
 
-#endif
+#endif //!LLVM_CODEGEN_SCOREBOARDHAZARDRECOGNIZER_H