[PATCH] D22193: Add macro-fusion hook in MIScheduler and support cluster instructions scheduling in PostRAScheduler

[Ehsan Amiri via llvm-commits]

amehsan added inline comments.

================
Comment at: lib/CodeGen/MachineScheduler.cpp:3108-3129
@@ -3107,20 +3107,24 @@
 /// default scheduler if the target does not set a default.
 static ScheduleDAGInstrs *createGenericSchedLive(MachineSchedContext *C) {
   ScheduleDAGMILive *DAG = new ScheduleDAGMILive(C, make_unique<GenericScheduler>(C));
   // Register DAG post-processors.
   //
   // FIXME: extend the mutation API to allow earlier mutations to instantiate
   // data and pass it to later mutations. Have a single mutation that gathers
   // the interesting nodes in one pass.
   DAG->addMutation(make_unique<CopyConstrain>(DAG->TII, DAG->TRI));
   if (EnableMemOpCluster) {
     if (DAG->TII->enableClusterLoads())
       DAG->addMutation(make_unique<LoadClusterMutation>(DAG->TII, DAG->TRI));
     if (DAG->TII->enableClusterStores())
       DAG->addMutation(make_unique<StoreClusterMutation>(DAG->TII, DAG->TRI));
   }
-  if (EnableMacroFusion)
-    DAG->addMutation(make_unique<MacroFusion>(*DAG->TII, *DAG->TRI));
+  if (EnableMacroFusion) {
+    if (ScheduleDAGMutation *Fusion = C->PassConfig->createMacroFusion(DAG))
+      DAG->addMutation(std::unique_ptr<ScheduleDAGMutation>(Fusion));
+    else
+      DAG->addMutation(make_unique<MacroFusion>(*DAG->TII, *DAG->TRI));
+  }
   return DAG;
 }
 
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Why not adding Target specific code to create scheduler objects and add any  mutations that we need,  there? What we want to do here, is Target specific and I think sooner or later we will have other target specific requirements to satisfy when creating scheduler, strategy and mutations. Why do you want to do this here?



================
Comment at: lib/CodeGen/PostRASchedulerList.cpp:465-471
@@ -461,4 +464,9 @@
 
   if (SuccEdge->isWeak()) {
     --SuccSU->WeakPredsLeft;
+    // Cluster instructions get higher scheduling priority.
+    // If SuccSU is not blocked by any other predecessors, let scheduler pick
+    // SuccSU as next scheduling instruction.
+    if (SuccEdge->isCluster() && SuccSU->NumPredsLeft == 0)
+      NextClusterSucc = SuccSU;
     return;
----------------
I have doubts that we need to make any changes in this file. We want to switch to post-ra MIScheduler. So I don't see much benefit in making changes here. 


http://reviews.llvm.org/D22193