Update CalcLatency to work in terms of edge latencies, rather than

node latencies. Use CalcLatency instead of manual code in
CalculatePriorities to keep it consistent. Previously it
computed slightly different results.

llvm-svn: 60817

1 files changed, 5 insertions, 26 deletions

diff --git a/llvm/lib/CodeGen/LatencyPriorityQueue.cpp b/llvm/lib/CodeGen/LatencyPriorityQueue.cpp
index 131da27c337..2abbf364e32 100644
--- a/llvm/lib/CodeGen/LatencyPriorityQueue.cpp
+++ b/llvm/lib/CodeGen/LatencyPriorityQueue.cpp
@@ -43,16 +43,15 @@ bool latency_sort::operator()(const SUnit *LHS, const SUnit *RHS) const {
 
 /// CalcNodePriority - Calculate the maximal path from the node to the exit.
 ///
-int LatencyPriorityQueue::CalcLatency(const SUnit &SU) {
+void LatencyPriorityQueue::CalcLatency(const SUnit &SU) {
   int &Latency = Latencies[SU.NodeNum];
   if (Latency != -1)
-    return Latency;
+    return;
 
   std::vector<const SUnit*> WorkList;
   WorkList.push_back(&SU);
   while (!WorkList.empty()) {
     const SUnit *Cur = WorkList.back();
-    unsigned CurLatency = Cur->Latency;
     bool AllDone = true;
     unsigned MaxSuccLatency = 0;
     for (SUnit::const_succ_iterator I = Cur->Succs.begin(),E = Cur->Succs.end();
@@ -62,8 +61,7 @@ int LatencyPriorityQueue::CalcLatency(const SUnit &SU) {
         AllDone = false;
         WorkList.push_back(I->getSUnit());
       } else {
-        // This assumes that there's no delay for reusing registers.
-        unsigned NewLatency = SuccLatency + CurLatency;
+        unsigned NewLatency = SuccLatency + I->getLatency();
         MaxSuccLatency = std::max(MaxSuccLatency, NewLatency);
       }
     }
@@ -72,8 +70,6 @@ int LatencyPriorityQueue::CalcLatency(const SUnit &SU) {
       WorkList.pop_back();
     }
   }
-
-  return Latency;
 }
 
 /// CalculatePriorities - Calculate priorities of all scheduling units.
@@ -82,25 +78,8 @@ void LatencyPriorityQueue::CalculatePriorities() {
   NumNodesSolelyBlocking.assign(SUnits->size(), 0);
 
   // For each node, calculate the maximal path from the node to the exit.
-  std::vector<std::pair<const SUnit*, unsigned> > WorkList;
-  for (unsigned i = 0, e = SUnits->size(); i != e; ++i) {
-    const SUnit *SU = &(*SUnits)[i];
-    if (SU->Succs.empty())
-      WorkList.push_back(std::make_pair(SU, 0U));
-  }
-
-  while (!WorkList.empty()) {
-    const SUnit *SU = WorkList.back().first;
-    unsigned SuccLat = WorkList.back().second;
-    WorkList.pop_back();
-    int &Latency = Latencies[SU->NodeNum];
-    if (Latency == -1 || (SU->Latency + SuccLat) > (unsigned)Latency) {
-      Latency = SU->Latency + SuccLat;
-      for (SUnit::const_pred_iterator I = SU->Preds.begin(),E = SU->Preds.end();
-           I != E; ++I)
-        WorkList.push_back(std::make_pair(I->getSUnit(), Latency));
-    }
-  }
+  for (unsigned i = 0, e = SUnits->size(); i != e; ++i)
+    CalcLatency((*SUnits)[i]);
 }
 
 /// getSingleUnscheduledPred - If there is exactly one unscheduled predecessor