Added class MachineSchedInfo and several supporting classes

as a machine description for instruction scheduling.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@397 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/TargetMachine/TargetMachine.cpp

@@ -24,6 +24,16 @@
 // 
 const MachineInstrDescriptor* TargetInstrDescriptors = NULL;
 
+resourceId_t MachineResource::nextId = 0;
+
+//************************* Forward Declarations **************************/
+
+static cycles_t	ComputeMinGap		(const InstrRUsage& fromRU,
+					 const InstrRUsage& toRU);
+
+static bool	RUConflict		(const vector<resourceId_t>& fromRVec,
+					 const vector<resourceId_t>& fromRVec);
+
 
 //************************ Class Implementations **************************/
 
@@ -66,8 +76,9 @@ unsigned int TargetMachine::findOptimalStorageSize(const Type* ty) const {
 
 /*ctor*/
 MachineInstrInfo::MachineInstrInfo(const MachineInstrDescriptor* _desc,
-				   unsigned int _descSize)
-  : desc(_desc), descSize(_descSize)
+				   unsigned int _descSize,
+				   unsigned int _numRealOpCodes)
+  : desc(_desc), descSize(_descSize), numRealOpCodes(_numRealOpCodes)
 {
   assert(TargetInstrDescriptors == NULL && desc != NULL);
   TargetInstrDescriptors = desc;	// initialize global variable
@@ -99,4 +110,186 @@ MachineInstrInfo::constantFitsInImmedField(MachineOpCode opCode,
   return false;
 }
 
+
+//---------------------------------------------------------------------------
+// class MachineSchedInfo
+//	Interface to machine description for instruction scheduling
+//---------------------------------------------------------------------------
+
+/*ctor*/
+MachineSchedInfo::MachineSchedInfo(int                     _numSchedClasses,
+				   const MachineInstrInfo* _mii,
+				   const InstrClassRUsage* _classRUsages,
+				   const InstrRUsageDelta* _usageDeltas,
+				   const InstrIssueDelta*  _issueDeltas,
+				   unsigned int		   _numUsageDeltas,
+				   unsigned int		   _numIssueDeltas)
+  : numSchedClasses(_numSchedClasses),
+    mii(_mii),
+    classRUsages(_classRUsages),
+    usageDeltas(_usageDeltas),
+    issueDeltas(_issueDeltas),
+    numUsageDeltas(_numUsageDeltas),
+    numIssueDeltas(_numIssueDeltas)
+{
+}
+
+void
+MachineSchedInfo::initializeResources()
+{
+  assert(MAX_NUM_SLOTS >= (int) getMaxNumIssueTotal()
+	 && "Insufficient slots for static data! Increase MAX_NUM_SLOTS");
+  
+  // First, compute common resource usage info for each class because
+  // most instructions will probably behave the same as their class.
+  // Cannot allocate a vector of InstrRUsage so new each one.
+  // 
+  vector<InstrRUsage> instrRUForClasses;
+  instrRUForClasses.resize(numSchedClasses);
+  for (InstrSchedClass sc=0; sc < numSchedClasses; sc++)
+    {
+      // instrRUForClasses.push_back(new InstrRUsage);
+      instrRUForClasses[sc].setMaxSlots(getMaxNumIssueTotal());
+      instrRUForClasses[sc] = classRUsages[sc];
+    }
+  
+  computeInstrResources(instrRUForClasses);
+  
+  computeIssueGaps(instrRUForClasses);
+}
+
+
+void
+MachineSchedInfo::computeInstrResources(const vector<InstrRUsage>& instrRUForClasses)
+{
+  int numOpCodes =  mii->getNumRealOpCodes();
+  instrRUsages.resize(numOpCodes);
+  
+  // First get the resource usage information from the class resource usages.
+  for (MachineOpCode op=0; op < numOpCodes; op++)
+    {
+      InstrSchedClass sc = getSchedClass(op);
+      assert(sc >= 0 && sc < numSchedClasses);
+      instrRUsages[op] = instrRUForClasses[sc];
+    }
+  
+  // Now, modify the resource usages as specified in the deltas.
+  for (unsigned i=0; i < numUsageDeltas; i++)
+    {
+      MachineOpCode op = usageDeltas[i].opCode;
+      assert(op < numOpCodes);
+      instrRUsages[op].addUsageDelta(usageDeltas[i]);
+    }
+  
+  // Then modify the issue restrictions as specified in the deltas.
+  for (unsigned i=0; i < numIssueDeltas; i++)
+    {
+      MachineOpCode op = issueDeltas[i].opCode;
+      assert(op < numOpCodes);
+      instrRUsages[issueDeltas[i].opCode].addIssueDelta(issueDeltas[i]);
+    }
+}
+
+
+void
+MachineSchedInfo::computeIssueGaps(const vector<InstrRUsage>& instrRUForClasses)
+{
+  int numOpCodes =  mii->getNumRealOpCodes();
+  instrRUsages.resize(numOpCodes);
+  
+  assert(numOpCodes < (1 << MAX_OPCODE_SIZE) - 1
+	 && "numOpCodes invalid for implementation of class OpCodePair!");
+  
+  // First, compute issue gaps between pairs of classes based on common
+  // resources usages for each class, because most instruction pairs will
+  // usually behave the same as their class.
+  // 
+  int classPairGaps[numSchedClasses][numSchedClasses];
+  for (InstrSchedClass fromSC=0; fromSC < numSchedClasses; fromSC++)
+    for (InstrSchedClass toSC=0; toSC < numSchedClasses; toSC++)
+      {
+	int classPairGap = ComputeMinGap(instrRUForClasses[fromSC],
+				      instrRUForClasses[toSC]);
+	classPairGaps[fromSC][toSC] = classPairGap; 
+      }
+  
+  // Now, for each pair of instructions, use the class pair gap if both
+  // instructions have identical resource usage as their respective classes.
+  // If not, recompute the gap for the pair from scratch.
+
+  longestIssueConflict = 0;
+  
+  for (MachineOpCode fromOp=0; fromOp < numOpCodes; fromOp++)
+    for (MachineOpCode toOp=0; toOp < numOpCodes; toOp++)
+    {
+      int instrPairGap = 
+	(instrRUsages[fromOp].sameAsClass && instrRUsages[toOp].sameAsClass)
+	? classPairGaps[getSchedClass(fromOp)][getSchedClass(toOp)]
+	: ComputeMinGap(instrRUsages[fromOp], instrRUsages[toOp]);
+      
+      if (instrPairGap > 0)
+	{
+	  issueGaps[OpCodePair(fromOp,toOp)] = instrPairGap;
+	  conflictLists[fromOp].push_back(toOp);
+	  longestIssueConflict = max(longestIssueConflict, instrPairGap);
+	}
+    }
+}
+
+
+// Check if fromRVec and toRVec have *any* common entries.
+// Assume the vectors are sorted in increasing order.
+// Algorithm copied from function set_intersection() for sorted ranges (stl_algo.h).
+inline static bool 
+RUConflict(const vector<resourceId_t>& fromRVec,
+	   const vector<resourceId_t>& toRVec)
+{
+  bool commonElementFound = false;
+  
+  unsigned fN = fromRVec.size(), tN = toRVec.size(); 
+  unsigned fi = 0, ti = 0;
+  while (fi < fN && ti < tN)
+    if (fromRVec[fi] < toRVec[ti])
+      ++fi;
+    else if (toRVec[ti] < fromRVec[fi])
+      ++ti;
+    else
+      {
+	commonElementFound = true;
+	break;
+      }
+  
+  return commonElementFound; 
+}
+
+
+static cycles_t
+ComputeMinGap(const InstrRUsage& fromRU, const InstrRUsage& toRU)
+{
+  cycles_t minGap = 0;
+  
+  if (fromRU.numBubbles > 0)
+    minGap = fromRU.numBubbles;
+  
+  if (minGap < fromRU.numCycles)
+    {
+      // only need to check from cycle `minGap' onwards
+      for (cycles_t gap=minGap; gap <= fromRU.numCycles-1; gap++)
+	{
+	  // check if instr. #2 can start executing `gap' cycles after #1
+	  // by checking for resource conflicts in each overlapping cycle
+	  cycles_t numOverlap = min(fromRU.numCycles - gap, toRU.numCycles);
+	  for (cycles_t c = 0; c <= numOverlap-1; c++)
+	    if (RUConflict(fromRU.resourcesByCycle[gap + c],
+			   toRU.resourcesByCycle[c]))
+	      {// conflict found so minGap must be more than `gap'
+		minGap = gap+1;
+		break;
+	      }
+	}
+    }
+  
+  return minGap;
+}
+
 //---------------------------------------------------------------------------