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.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121274 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 29 insertions, 18 deletions

diff --git a/lib/CodeGen/CMakeLists.txt b/lib/CodeGen/CMakeLists.txt
index b5c1ff7f56..70e044d225 100644
--- a/lib/CodeGen/CMakeLists.txt
+++ b/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/lib/CodeGen/PostRAHazardRecognizer.cpp b/lib/CodeGen/ScoreboardHazardRecognizer.cpp
index 2e3919632f..d78b5d3ecb 100644
--- a/lib/CodeGen/PostRAHazardRecognizer.cpp
+++ b/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/lib/CodeGen/TargetInstrInfoImpl.cpp b/lib/CodeGen/TargetInstrInfoImpl.cpp
index cb2292d62b..baad14c5c7 100644
--- a/lib/CodeGen/TargetInstrInfoImpl.cpp
+++ b/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);
 }