[llvm] [MISched] Add statistics for heuristics (PR #137981)

[Cullen Rhodes via llvm-commits]

================
@@ -3420,13 +3511,137 @@ bool tryLatency(GenericSchedulerBase::SchedCandidate &TryCand,
 }
 } // end namespace llvm
 
-static void tracePick(GenericSchedulerBase::CandReason Reason, bool IsTop) {
+static void tracePick(GenericSchedulerBase::CandReason Reason, bool IsTop,
+                      bool IsPostRA = false) {
   LLVM_DEBUG(dbgs() << "Pick " << (IsTop ? "Top " : "Bot ")
-                    << GenericSchedulerBase::getReasonStr(Reason) << '\n');
+                    << GenericSchedulerBase::getReasonStr(Reason) << " ["
+                    << (IsPostRA ? "post-RA" : "pre-RA") << "]\n");
+
+  if (IsPostRA) {
+    if (IsTop)
+      NumTopPostRA++;
+    else
+      NumBotPostRA++;
+
+    switch (Reason) {
+    case GenericScheduler::NoCand:
+      NumNoCandPostRA++;
+      return;
+    case GenericScheduler::Only1:
+      NumOnly1PostRA++;
+      return;
+    case GenericScheduler::PhysReg:
+      NumPhysRegPostRA++;
+      return;
+    case GenericScheduler::RegExcess:
+      NumRegExcessPostRA++;
+      return;
+    case GenericScheduler::RegCritical:
+      NumRegCriticalPostRA++;
+      return;
+    case GenericScheduler::Stall:
+      NumStallPostRA++;
+      return;
+    case GenericScheduler::Cluster:
+      NumClusterPostRA++;
+      return;
+    case GenericScheduler::Weak:
+      NumWeakPostRA++;
+      return;
+    case GenericScheduler::RegMax:
+      NumRegMaxPostRA++;
+      return;
+    case GenericScheduler::ResourceReduce:
+      NumResourceReducePostRA++;
+      return;
+    case GenericScheduler::ResourceDemand:
+      NumResourceDemandPostRA++;
+      return;
+    case GenericScheduler::TopDepthReduce:
+      NumTopDepthReducePostRA++;
+      return;
+    case GenericScheduler::TopPathReduce:
+      NumTopPathReducePostRA++;
+      return;
+    case GenericScheduler::BotHeightReduce:
+      NumBotHeightReducePostRA++;
+      return;
+    case GenericScheduler::BotPathReduce:
+      NumBotPathReducePostRA++;
+      return;
+    case GenericScheduler::NodeOrder:
+      NumNodeOrderPostRA++;
+      return;
+    case GenericScheduler::FirstValid:
+      NumFirstValidPostRA++;
+      return;
+    };
+  } else {
+    if (IsTop)
+      NumTopPreRA++;
+    else
+      NumBotPreRA++;
+
+    switch (Reason) {
+    case GenericScheduler::NoCand:
+      NumNoCandPreRA++;
+      return;
+    case GenericScheduler::Only1:
+      NumOnly1PreRA++;
+      return;
+    case GenericScheduler::PhysReg:
+      NumPhysRegPreRA++;
+      return;
+    case GenericScheduler::RegExcess:
+      NumRegExcessPreRA++;
+      return;
+    case GenericScheduler::RegCritical:
+      NumRegCriticalPreRA++;
+      return;
+    case GenericScheduler::Stall:
+      NumStallPreRA++;
+      return;
+    case GenericScheduler::Cluster:
+      NumClusterPreRA++;
+      return;
+    case GenericScheduler::Weak:
+      NumWeakPreRA++;
+      return;
+    case GenericScheduler::RegMax:
+      NumRegMaxPreRA++;
+      return;
+    case GenericScheduler::ResourceReduce:
+      NumResourceReducePreRA++;
+      return;
+    case GenericScheduler::ResourceDemand:
+      NumResourceDemandPreRA++;
+      return;
+    case GenericScheduler::TopDepthReduce:
+      NumTopDepthReducePreRA++;
+      return;
+    case GenericScheduler::TopPathReduce:
+      NumTopPathReducePreRA++;
+      return;
+    case GenericScheduler::BotHeightReduce:
+      NumBotHeightReducePreRA++;
+      return;
+    case GenericScheduler::BotPathReduce:
+      NumBotPathReducePreRA++;
+      return;
+    case GenericScheduler::NodeOrder:
+      NumNodeOrderPreRA++;
+      return;
+    case GenericScheduler::FirstValid:
+      NumFirstValidPreRA++;
+      return;
+    };
+  }
+  llvm_unreachable("Unknown reason!");
----------------
c-rhodes wrote:

it's a pretty standard use of unreachable as far as I'm aware: https://llvm.org/docs/ProgrammersManual.html#programmatic-errors

https://github.com/llvm/llvm-project/pull/137981