[llvm] r251037 - MachineScheduler: Add a way to disable the 'ReduceLatency' heuristic

[Matthias Braun via llvm-commits]

Author: matze
Date: Thu Oct 22 13:07:31 2015
New Revision: 251037

URL: http://llvm.org/viewvc/llvm-project?rev=251037&view=rev
Log:
MachineScheduler: Add a way to disable the 'ReduceLatency' heuristic

Modified:
    llvm/trunk/include/llvm/CodeGen/MachineScheduler.h
    llvm/trunk/lib/CodeGen/MachineScheduler.cpp

Modified: llvm/trunk/include/llvm/CodeGen/MachineScheduler.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CodeGen/MachineScheduler.h?rev=251037&r1=251036&r2=251037&view=diff
==============================================================================
--- llvm/trunk/include/llvm/CodeGen/MachineScheduler.h (original)
+++ llvm/trunk/include/llvm/CodeGen/MachineScheduler.h Thu Oct 22 13:07:31 2015
@@ -156,8 +156,12 @@ struct MachineSchedPolicy {
   bool OnlyTopDown;
   bool OnlyBottomUp;
 
+  // Disable heuristic that tries to fetch nodes from long dependency chains
+  // first.
+  bool DisableLatencyHeuristic;
+
   MachineSchedPolicy(): ShouldTrackPressure(false), OnlyTopDown(false),
-    OnlyBottomUp(false) {}
+    OnlyBottomUp(false), DisableLatencyHeuristic(false) {}
 };
 
 /// MachineSchedStrategy - Interface to the scheduling algorithm used by

Modified: llvm/trunk/lib/CodeGen/MachineScheduler.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/MachineScheduler.cpp?rev=251037&r1=251036&r2=251037&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/MachineScheduler.cpp (original)
+++ llvm/trunk/lib/CodeGen/MachineScheduler.cpp Thu Oct 22 13:07:31 2015
@@ -2722,8 +2722,8 @@ void GenericScheduler::tryCandidate(Sche
 
   // Avoid serializing long latency dependence chains.
   // For acyclic path limited loops, latency was already checked above.
-  if (Cand.Policy.ReduceLatency && !Rem.IsAcyclicLatencyLimited
-      && tryLatency(TryCand, Cand, Zone)) {
+  if (!RegionPolicy.DisableLatencyHeuristic && Cand.Policy.ReduceLatency &&
+      !Rem.IsAcyclicLatencyLimited && tryLatency(TryCand, Cand, Zone)) {
     return;
   }