Various bits of framework needed for precise machine-level selection

DAG scheduling during isel. Most new functionality is currently
guarded by -enable-sched-cycles and -enable-sched-hazard.

Added InstrItineraryData::IssueWidth field, currently derived from
ARM itineraries, but could be initialized differently on other targets.

Added ScheduleHazardRecognizer::MaxLookAhead to indicate whether it is
active, and if so how many cycles of state it holds.

Added SchedulingPriorityQueue::HasReadyFilter to allowing gating entry
into the scheduler's available queue.

ScoreboardHazardRecognizer now accesses the ScheduleDAG in order to
get information about it's SUnits, provides RecedeCycle for bottom-up
scheduling, correctly computes scoreboard depth, tracks IssueCount, and
considers potential stall cycles when checking for hazards.

ScheduleDAGRRList now models machine cycles and hazards (under
flags). It tracks MinAvailableCycle, drives the hazard recognizer and
priority queue's ready filter, manages a new PendingQueue, properly
accounts for stall cycles, etc.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122541 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 26 insertions, 2 deletions

diff --git a/include/llvm/CodeGen/ScoreboardHazardRecognizer.h b/include/llvm/CodeGen/ScoreboardHazardRecognizer.h
index 561bf0fecf..8850006df8 100644
--- a/include/llvm/CodeGen/ScoreboardHazardRecognizer.h
+++ b/include/llvm/CodeGen/ScoreboardHazardRecognizer.h
@@ -26,6 +26,8 @@
 namespace llvm {
 
 class InstrItineraryData;
+class TargetInstrDesc;
+class ScheduleDAG;
 class SUnit;
 
 class ScoreboardHazardRecognizer : public ScheduleHazardRecognizer {
@@ -84,16 +86,38 @@ class ScoreboardHazardRecognizer : public ScheduleHazardRecognizer {
     void dump() const;
   };
 
+#ifndef NDEBUG
+  // Support for tracing ScoreboardHazardRecognizer as a component within
+  // another module. Follows the current thread-unsafe model of tracing.
+  static const char *DebugType;
+#endif
+
   // Itinerary data for the target.
   const InstrItineraryData *ItinData;
 
+  const ScheduleDAG *DAG;
+
+  /// IssueWidth - Max issue per cycle. 0=Unknown.
+  unsigned IssueWidth;
+
+  /// IssueCount - Count instructions issued in this cycle.
+  unsigned IssueCount;
+
   Scoreboard ReservedScoreboard;
   Scoreboard RequiredScoreboard;
 
 public:
-  ScoreboardHazardRecognizer(const InstrItineraryData *ItinData);
+  ScoreboardHazardRecognizer(const InstrItineraryData *ItinData,
+                             const ScheduleDAG *DAG,
+                             const char *ParentDebugType = "");
+
+  /// atIssueLimit - Return true if no more instructions may be issued in this
+  /// cycle.
+  virtual bool atIssueLimit() const;
 
-  virtual HazardType getHazardType(SUnit *SU);
+  // Stalls provides an cycle offset at which SU will be scheduled. It will be
+  // negative for bottom-up scheduling.
+  virtual HazardType getHazardType(SUnit *SU, int Stalls);
   virtual void Reset();
   virtual void EmitInstruction(SUnit *SU);
   virtual void AdvanceCycle();