MachineScheduler: Remove ineffective heuristic; NFC

Currently all nodes get added to the NextSU list when they are released,
so any candidate must be in that list, making the heuristic ineffective.
Remove it for now, we can add it back later in a working fashion if
necessary.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@282200 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/CodeGen/MachineScheduler.h b/include/llvm/CodeGen/MachineScheduler.h
index 741a5299a900d119897c366757c648d57b5668c3..25a6105b689b4b137498badbeb833a9befa8a336 100644 (file)
--- a/include/llvm/CodeGen/MachineScheduler.h
+++ b/include/llvm/CodeGen/MachineScheduler.h
@@ -589,10 +589,6 @@ private:
   /// instruction.
   bool CheckPending;
 
-  // For heuristics, keep a list of the nodes that immediately depend on the
-  // most recently scheduled node.
-  SmallPtrSet<const SUnit*, 8> NextSUs;
-
   /// Number of cycles it takes to issue the instructions scheduled in this
   /// zone. It is defined as: scheduled-micro-ops / issue-width + stalls.
   /// See getStalls().
@@ -669,10 +665,6 @@ public:
   /// Micro-ops issued in the current cycle
   unsigned getCurrMOps() const { return CurrMOps; }
 
-  /// Return true if the given SU is used by the most recently scheduled
-  /// instruction.
-  bool isNextSU(const SUnit *SU) const { return NextSUs.count(SU); }
-
   // The latency of dependence chains leading into this zone.
   unsigned getDependentLatency() const { return DependentLatency; }
 

diff --git a/lib/CodeGen/MachineScheduler.cpp b/lib/CodeGen/MachineScheduler.cpp
index fae22eb9b2593457b269e95d740ea80d3686a301..bc1c97d7466fafc357960b06e55791ce4e242a28 100644 (file)
--- a/lib/CodeGen/MachineScheduler.cpp
+++ b/lib/CodeGen/MachineScheduler.cpp
@@ -1793,7 +1793,6 @@ void SchedBoundary::reset() {
   Available.clear();
   Pending.clear();
   CheckPending = false;
-  NextSUs.clear();
   CurrCycle = 0;
   CurrMOps = 0;
   MinReadyCycle = UINT_MAX;
@@ -1994,9 +1993,6 @@ void SchedBoundary::releaseNode(SUnit *SU, unsigned ReadyCycle) {
     Pending.push(SU);
   else
     Available.push(SU);
-
-  // Record this node as an immediate dependent of the scheduled node.
-  NextSUs.insert(SU);
 }
 
 void SchedBoundary::releaseTopNode(SUnit *SU) {
@@ -2921,13 +2917,6 @@ void GenericScheduler::tryCandidate(SchedCandidate &Cand,
         !Rem.IsAcyclicLatencyLimited && tryLatency(TryCand, Cand, *Zone))
       return;
 
-    // Prefer immediate defs/users of the last scheduled instruction. This is a
-    // local pressure avoidance strategy that also makes the machine code
-    // readable.
-    if (tryGreater(Zone->isNextSU(TryCand.SU), Zone->isNextSU(Cand.SU),
-                   TryCand, Cand, NextDefUse))
-      return;
-
     // Fall through to original instruction order.
     if ((Zone->isTop() && TryCand.SU->NodeNum < Cand.SU->NodeNum)
         || (!Zone->isTop() && TryCand.SU->NodeNum > Cand.SU->NodeNum)) {