[llvm-commits] [llvm] r59775 - /llvm/trunk/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp

[Dan Gohman]

Author: djg
Date: Thu Nov 20 19:30:54 2008
New Revision: 59775

URL: http://llvm.org/viewvc/llvm-project?rev=59775&view=rev
Log:
Remove the CycleBound computation code from the ScheduleDAGRRList
schedulers. This doesn't have much immediate impact because
targets that use these schedulers by default don't yet provide
pipeline information.

This code also didn't have the benefit of register pressure
information. Also, removing it will avoid problems with list-burr
suddenly starting to do latency-oriented scheduling on x86 when we
start providing pipeline data, which would increase spilling.

Modified:
    llvm/trunk/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp

Modified: llvm/trunk/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp?rev=59775&r1=59774&r2=59775&view=diff

==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp Thu Nov 20 19:30:54 2008
@@ -270,19 +270,6 @@
   }
 #endif
   
-  // Compute how many cycles it will be before this actually becomes
-  // available.  This is the max of the start time of all predecessors plus
-  // their latencies.
-  // If this is a token edge, we don't need to wait for the latency of the
-  // preceeding instruction (e.g. a long-latency load) unless there is also
-  // some other data dependence.
-  unsigned PredDoneCycle = SU->Cycle;
-  if (!isChain)
-    PredDoneCycle += PredSU->Latency;
-  else if (SU->Latency)
-    PredDoneCycle += 1;
-  PredSU->CycleBound = std::max(PredSU->CycleBound, PredDoneCycle);
-
   if (PredSU->NumSuccsLeft == 0) {
     PredSU->isAvailable = true;
     AvailableQueue->push(PredSU);
@@ -339,22 +326,12 @@
 /// unscheduled, incrcease the succ left count of its predecessors. Remove
 /// them from AvailableQueue if necessary.
 void ScheduleDAGRRList::CapturePred(SUnit *PredSU, SUnit *SU, bool isChain) {  
-  unsigned CycleBound = 0;
-  for (SUnit::succ_iterator I = PredSU->Succs.begin(), E = PredSU->Succs.end();
-       I != E; ++I) {
-    if (I->Dep == SU)
-      continue;
-    CycleBound = std::max(CycleBound,
-                          I->Dep->Cycle + PredSU->Latency);
-  }
-
   if (PredSU->isAvailable) {
     PredSU->isAvailable = false;
     if (!PredSU->isPending)
       AvailableQueue->remove(PredSU);
   }
 
-  PredSU->CycleBound = CycleBound;
   ++PredSU->NumSuccsLeft;
 }
 
@@ -948,13 +925,11 @@
     LRegsMap.clear();
     SUnit *CurSU = AvailableQueue->pop();
     while (CurSU) {
-      if (CurSU->CycleBound <= CurCycle) {
-        SmallVector<unsigned, 4> LRegs;
-        if (!DelayForLiveRegsBottomUp(CurSU, LRegs))
-          break;
-        Delayed = true;
-        LRegsMap.insert(std::make_pair(CurSU, LRegs));
-      }
+      SmallVector<unsigned, 4> LRegs;
+      if (!DelayForLiveRegsBottomUp(CurSU, LRegs))
+        break;
+      Delayed = true;
+      LRegsMap.insert(std::make_pair(CurSU, LRegs));
 
       CurSU->isPending = true;  // This SU is not in AvailableQueue right now.
       NotReady.push_back(CurSU);
@@ -1083,19 +1058,6 @@
   }
 #endif
   
-  // Compute how many cycles it will be before this actually becomes
-  // available.  This is the max of the start time of all predecessors plus
-  // their latencies.
-  // If this is a token edge, we don't need to wait for the latency of the
-  // preceeding instruction (e.g. a long-latency load) unless there is also
-  // some other data dependence.
-  unsigned PredDoneCycle = SU->Cycle;
-  if (!isChain)
-    PredDoneCycle += SU->Latency;
-  else if (SU->Latency)
-    PredDoneCycle += 1;
-  SuccSU->CycleBound = std::max(SuccSU->CycleBound, PredDoneCycle);
-
   if (SuccSU->NumPredsLeft == 0) {
     SuccSU->isAvailable = true;
     AvailableQueue->push(SuccSU);
@@ -1137,19 +1099,10 @@
   
   // While Available queue is not empty, grab the node with the highest
   // priority. If it is not ready put it back.  Schedule the node.
-  std::vector<SUnit*> NotReady;
   Sequence.reserve(SUnits.size());
   while (!AvailableQueue->empty()) {
     SUnit *CurSU = AvailableQueue->pop();
-    while (CurSU && CurSU->CycleBound > CurCycle) {
-      NotReady.push_back(CurSU);
-      CurSU = AvailableQueue->pop();
-    }
     
-    // Add the nodes that aren't ready back onto the available list.
-    AvailableQueue->push_all(NotReady);
-    NotReady.clear();
-
     if (CurSU)
       ScheduleNodeTopDown(CurSU, CurCycle);
     ++CurCycle;
@@ -1433,9 +1386,6 @@
   if (left->Depth != right->Depth)
     return left->Depth < right->Depth;
 
-  if (left->CycleBound != right->CycleBound)
-    return left->CycleBound > right->CycleBound;
-
   assert(left->NodeQueueId && right->NodeQueueId && 
          "NodeQueueId cannot be zero");
   return (left->NodeQueueId > right->NodeQueueId);
@@ -1636,9 +1586,6 @@
   if (left->NumSuccsLeft != right->NumSuccsLeft)
     return left->NumSuccsLeft > right->NumSuccsLeft;
 
-  if (left->CycleBound != right->CycleBound)
-    return left->CycleBound > right->CycleBound;
-
   assert(left->NodeQueueId && right->NodeQueueId && 
          "NodeQueueId cannot be zero");
   return (left->NodeQueueId > right->NodeQueueId);