[MISched][NFC] Remove unused heuristic NextDefUse from enum (#125879)

Heuristic was removed in 46533e6 due to being ineffective.

Author: c-rhodes

llvm/include/llvm/CodeGen/MachineScheduler.h

@@ -1084,9 +1084,23 @@ class GenericSchedulerBase : public MachineSchedStrategy {
   /// Represent the type of SchedCandidate found within a single queue.
   /// pickNodeBidirectional depends on these listed by decreasing priority.
   enum CandReason : uint8_t {
-    NoCand, Only1, PhysReg, RegExcess, RegCritical, Stall, Cluster, Weak,
-    RegMax, ResourceReduce, ResourceDemand, BotHeightReduce, BotPathReduce,
-    TopDepthReduce, TopPathReduce, NextDefUse, NodeOrder};
+    NoCand,
+    Only1,
+    PhysReg,
+    RegExcess,
+    RegCritical,
+    Stall,
+    Cluster,
+    Weak,
+    RegMax,
+    ResourceReduce,
+    ResourceDemand,
+    BotHeightReduce,
+    BotPathReduce,
+    TopDepthReduce,
+    TopPathReduce,
+    NodeOrder
+  };
 
 #ifndef NDEBUG
   static const char *getReasonStr(GenericSchedulerBase::CandReason Reason);

llvm/lib/CodeGen/MachineScheduler.cpp

@@ -3249,6 +3249,7 @@ void GenericSchedulerBase::setPolicy(CandPolicy &Policy, bool IsPostRA,
 #ifndef NDEBUG
 const char *GenericSchedulerBase::getReasonStr(
   GenericSchedulerBase::CandReason Reason) {
+  // clang-format off
   switch (Reason) {
   case NoCand:         return "NOCAND    ";
   case Only1:          return "ONLY1     ";
@@ -3265,9 +3266,9 @@ const char *GenericSchedulerBase::getReasonStr(
   case TopPathReduce:  return "TOP-PATH  ";
   case BotHeightReduce:return "BOT-HEIGHT";
   case BotPathReduce:  return "BOT-PATH  ";
-  case NextDefUse:     return "DEF-USE   ";
   case NodeOrder:      return "ORDER     ";
   };
+  // clang-format on
   llvm_unreachable("Unknown reason!");
 }