Generalize PostRAHazardRecognizer so it can be used in any pass for

both forward and backward scheduling. Rename it to
ScoreboardHazardRecognizer (Scoreboard is one word). Remove integer
division from the scoreboard's critical path.

llvm-svn: 121274

5 files changed, 41 insertions, 26 deletions

diff --git a/llvm/lib/CodeGen/CMakeLists.txt b/llvm/lib/CodeGen/CMakeLists.txt
index b5c1ff7f563..70e044d225b 100644
--- a/llvm/lib/CodeGen/CMakeLists.txt
+++ b/llvm/lib/CodeGen/CMakeLists.txt
@@ -53,7 +53,7 @@ add_llvm_library(LLVMCodeGen
   PHIEliminationUtils.cpp
   Passes.cpp
   PeepholeOptimizer.cpp
-  PostRAHazardRecognizer.cpp
+  ScoreboardHazardRecognizer.cpp
   PostRASchedulerList.cpp
   PreAllocSplitting.cpp
   ProcessImplicitDefs.cpp
diff --git a/llvm/lib/CodeGen/PostRAHazardRecognizer.cpp b/llvm/lib/CodeGen/ScoreboardHazardRecognizer.cpp
index 2e3919632f8..d78b5d3ecbd 100644
--- a/llvm/lib/CodeGen/PostRAHazardRecognizer.cpp
+++ b/llvm/lib/CodeGen/ScoreboardHazardRecognizer.cpp
@@ -1,4 +1,4 @@
-//===----- PostRAHazardRecognizer.cpp - hazard recognizer -------- ---------===//
+//===----- ScoreboardHazardRecognizer.cpp - Scheduler Support -------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
@@ -7,13 +7,14 @@
 //
 //===----------------------------------------------------------------------===//
 //
-// This implements a hazard recognizer using the instructions itineraries
-// defined for the current target.
+// This file implements the ScoreboardHazardRecognizer class, which
+// encapsultes hazard-avoidance heuristics for scheduling, based on the
+// scheduling itineraries specified for the target.
 //
 //===----------------------------------------------------------------------===//
 
-#define DEBUG_TYPE "post-RA-sched"
-#include "llvm/CodeGen/PostRAHazardRecognizer.h"
+#define DEBUG_TYPE "sched-hazard"
+#include "llvm/CodeGen/ScoreboardHazardRecognizer.h"
 #include "llvm/CodeGen/ScheduleDAG.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/ErrorHandling.h"
@@ -22,8 +23,8 @@
 
 using namespace llvm;
 
-PostRAHazardRecognizer::
-PostRAHazardRecognizer(const InstrItineraryData *LItinData) :
+ScoreboardHazardRecognizer::
+ScoreboardHazardRecognizer(const InstrItineraryData *LItinData) :
   ScheduleHazardRecognizer(), ItinData(LItinData) {
   // Determine the maximum depth of any itinerary. This determines the
   // depth of the scoreboard. We always make the scoreboard at least 1
@@ -40,23 +41,26 @@ PostRAHazardRecognizer(const InstrItineraryData *LItinData) :
       for (; IS != E; ++IS)
         ItinDepth += IS->getCycles();
 
-      ScoreboardDepth = std::max(ScoreboardDepth, ItinDepth);
+      // Find the next power-of-2 >= ItinDepth
+      while (ItinDepth > ScoreboardDepth) {
+        ScoreboardDepth *= 2;
+      }
     }
   }
 
   ReservedScoreboard.reset(ScoreboardDepth);
   RequiredScoreboard.reset(ScoreboardDepth);
 
-  DEBUG(dbgs() << "Using post-ra hazard recognizer: ScoreboardDepth = " 
+  DEBUG(dbgs() << "Using scoreboard hazard recognizer: Depth = "
                << ScoreboardDepth << '\n');
 }
 
-void PostRAHazardRecognizer::Reset() {
+void ScoreboardHazardRecognizer::Reset() {
   RequiredScoreboard.reset();
   ReservedScoreboard.reset();
 }
 
-void PostRAHazardRecognizer::ScoreBoard::dump() const {
+void ScoreboardHazardRecognizer::Scoreboard::dump() const {
   dbgs() << "Scoreboard:\n";
 
   unsigned last = Depth - 1;
@@ -73,7 +77,7 @@ void PostRAHazardRecognizer::ScoreBoard::dump() const {
 }
 
 ScheduleHazardRecognizer::HazardType
-PostRAHazardRecognizer::getHazardType(SUnit *SU) {
+ScoreboardHazardRecognizer::getHazardType(SUnit *SU) {
   if (!ItinData || ItinData->isEmpty())
     return NoHazard;
 
@@ -120,7 +124,7 @@ PostRAHazardRecognizer::getHazardType(SUnit *SU) {
   return NoHazard;
 }
 
-void PostRAHazardRecognizer::EmitInstruction(SUnit *SU) {
+void ScoreboardHazardRecognizer::EmitInstruction(SUnit *SU) {
   if (!ItinData || ItinData->isEmpty())
     return;
 
@@ -174,7 +178,14 @@ void PostRAHazardRecognizer::EmitInstruction(SUnit *SU) {
   DEBUG(RequiredScoreboard.dump());
 }
 
-void PostRAHazardRecognizer::AdvanceCycle() {
+void ScoreboardHazardRecognizer::AdvanceCycle() {
   ReservedScoreboard[0] = 0; ReservedScoreboard.advance();
   RequiredScoreboard[0] = 0; RequiredScoreboard.advance();
 }
+
+void ScoreboardHazardRecognizer::RecedeCycle() {
+  ReservedScoreboard[ReservedScoreboard.getDepth()-1] = 0;
+  ReservedScoreboard.recede();
+  RequiredScoreboard[RequiredScoreboard.getDepth()-1] = 0;
+  RequiredScoreboard.recede();
+}
diff --git a/llvm/lib/CodeGen/TargetInstrInfoImpl.cpp b/llvm/lib/CodeGen/TargetInstrInfoImpl.cpp
index cb2292d62be..baad14c5c76 100644
--- a/llvm/lib/CodeGen/TargetInstrInfoImpl.cpp
+++ b/llvm/lib/CodeGen/TargetInstrInfoImpl.cpp
@@ -22,7 +22,7 @@
 #include "llvm/CodeGen/MachineInstrBuilder.h"
 #include "llvm/CodeGen/MachineMemOperand.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
-#include "llvm/CodeGen/PostRAHazardRecognizer.h"
+#include "llvm/CodeGen/ScoreboardHazardRecognizer.h"
 #include "llvm/CodeGen/PseudoSourceValue.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/ErrorHandling.h"
@@ -135,7 +135,7 @@ bool TargetInstrInfoImpl::PredicateInstruction(MachineInstr *MI,
   const TargetInstrDesc &TID = MI->getDesc();
   if (!TID.isPredicable())
     return false;
-  
+
   for (unsigned j = 0, i = 0, e = MI->getNumOperands(); i != e; ++i) {
     if (TID.OpInfo[i].isPredicate()) {
       MachineOperand &MO = MI->getOperand(i);
@@ -417,5 +417,5 @@ bool TargetInstrInfoImpl::isSchedulingBoundary(const MachineInstr *MI,
 // Default implementation of CreateTargetPostRAHazardRecognizer.
 ScheduleHazardRecognizer *TargetInstrInfoImpl::
 CreateTargetPostRAHazardRecognizer(const InstrItineraryData *II) const {
-  return (ScheduleHazardRecognizer *)new PostRAHazardRecognizer(II);
+  return (ScheduleHazardRecognizer *)new ScoreboardHazardRecognizer(II);
 }
diff --git a/llvm/lib/Target/ARM/ARMHazardRecognizer.cpp b/llvm/lib/Target/ARM/ARMHazardRecognizer.cpp
index 317934faec5..b8d385b6e3d 100644
--- a/llvm/lib/Target/ARM/ARMHazardRecognizer.cpp
+++ b/llvm/lib/Target/ARM/ARMHazardRecognizer.cpp
@@ -68,14 +68,14 @@ ARMHazardRecognizer::getHazardType(SUnit *SU) {
     }
   }
 
-  return PostRAHazardRecognizer::getHazardType(SU);
+  return ScoreboardHazardRecognizer::getHazardType(SU);
 }
 
 void ARMHazardRecognizer::Reset() {
   LastMI = 0;
   Stalls = 0;
   ITBlockSize = 0;
-  PostRAHazardRecognizer::Reset();
+  ScoreboardHazardRecognizer::Reset();
 }
 
 void ARMHazardRecognizer::EmitInstruction(SUnit *SU) {
@@ -103,12 +103,16 @@ void ARMHazardRecognizer::EmitInstruction(SUnit *SU) {
     Stalls = 0;
   }
 
-  PostRAHazardRecognizer::EmitInstruction(SU);
+  ScoreboardHazardRecognizer::EmitInstruction(SU);
 }
 
 void ARMHazardRecognizer::AdvanceCycle() {
   if (Stalls && --Stalls == 0)
     // Stalled for 4 cycles but still can't schedule any other instructions.
     LastMI = 0;
-  PostRAHazardRecognizer::AdvanceCycle();
+  ScoreboardHazardRecognizer::AdvanceCycle();
+}
+
+void ARMHazardRecognizer::RecedeCycle() {
+  llvm_unreachable("reverse ARM hazard checking unsupported");
 }
diff --git a/llvm/lib/Target/ARM/ARMHazardRecognizer.h b/llvm/lib/Target/ARM/ARMHazardRecognizer.h
index d1919d8cf49..9473bc52072 100644
--- a/llvm/lib/Target/ARM/ARMHazardRecognizer.h
+++ b/llvm/lib/Target/ARM/ARMHazardRecognizer.h
@@ -14,7 +14,7 @@
 #ifndef ARMHAZARDRECOGNIZER_H
 #define ARMHAZARDRECOGNIZER_H
 
-#include "llvm/CodeGen/PostRAHazardRecognizer.h"
+#include "llvm/CodeGen/ScoreboardHazardRecognizer.h"
 
 namespace llvm {
 
@@ -23,7 +23,7 @@ class ARMBaseRegisterInfo;
 class ARMSubtarget;
 class MachineInstr;
 
-class ARMHazardRecognizer : public PostRAHazardRecognizer {
+class ARMHazardRecognizer : public ScoreboardHazardRecognizer {
   const ARMBaseInstrInfo &TII;
   const ARMBaseRegisterInfo &TRI;
   const ARMSubtarget &STI;
@@ -38,16 +38,16 @@ public:
                       const ARMBaseInstrInfo &tii,
                       const ARMBaseRegisterInfo &tri,
                       const ARMSubtarget &sti) :
-    PostRAHazardRecognizer(ItinData), TII(tii), TRI(tri), STI(sti),
+    ScoreboardHazardRecognizer(ItinData), TII(tii), TRI(tri), STI(sti),
     LastMI(0), ITBlockSize(0) {}
 
   virtual HazardType getHazardType(SUnit *SU);
   virtual void Reset();
   virtual void EmitInstruction(SUnit *SU);
   virtual void AdvanceCycle();
+  virtual void RecedeCycle();
 };
 
-
 } // end namespace llvm
 
 #endif // ARMHAZARDRECOGNIZER_H