[Sched] Add MacroFusion mutation if fusions are not empty (#72227)

We can get the fusions list by `getMacroFusions` and if it is not
empty, then we will add the MacroFusion mutation automatically.

Author: wangpc-pp

llvm/lib/CodeGen/MachineScheduler.cpp

@@ -3804,6 +3804,12 @@ ScheduleDAGMILive *llvm::createGenericSchedLive(MachineSchedContext *C) {
   // data and pass it to later mutations. Have a single mutation that gathers
   // the interesting nodes in one pass.
   DAG->addMutation(createCopyConstrainDAGMutation(DAG->TII, DAG->TRI));
+
+  const TargetSubtargetInfo &STI = C->MF->getSubtarget();
+  // Add MacroFusion mutation if fusions are not empty.
+  const auto &MacroFusions = STI.getMacroFusions();
+  if (!MacroFusions.empty())
+    DAG->addMutation(createMacroFusionDAGMutation(MacroFusions));
   return DAG;
 }
 
@@ -3953,8 +3959,15 @@ void PostGenericScheduler::schedNode(SUnit *SU, bool IsTopNode) {
 }
 
 ScheduleDAGMI *llvm::createGenericSchedPostRA(MachineSchedContext *C) {
-  return new ScheduleDAGMI(C, std::make_unique<PostGenericScheduler>(C),
-                           /*RemoveKillFlags=*/true);
+  ScheduleDAGMI *DAG =
+      new ScheduleDAGMI(C, std::make_unique<PostGenericScheduler>(C),
+                        /*RemoveKillFlags=*/true);
+  const TargetSubtargetInfo &STI = C->MF->getSubtarget();
+  // Add MacroFusion mutation if fusions are not empty.
+  const auto &MacroFusions = STI.getMacroFusions();
+  if (!MacroFusions.empty())
+    DAG->addMutation(createMacroFusionDAGMutation(MacroFusions));
+  return DAG;
 }
 
 //===----------------------------------------------------------------------===//

llvm/lib/Target/RISCV/RISCVTargetMachine.cpp

@@ -362,26 +362,9 @@ class RISCVPassConfig : public TargetPassConfig {
       DAG->addMutation(createLoadClusterDAGMutation(
           DAG->TII, DAG->TRI, /*ReorderWhileClustering=*/true));
     }
-    const auto &MacroFusions = ST.getMacroFusions();
-    if (!MacroFusions.empty()) {
-      DAG = DAG ? DAG : createGenericSchedLive(C);
-      DAG->addMutation(createMacroFusionDAGMutation(MacroFusions));
-    }
     return DAG;
   }
 
-  ScheduleDAGInstrs *
-  createPostMachineScheduler(MachineSchedContext *C) const override {
-    const RISCVSubtarget &ST = C->MF->getSubtarget<RISCVSubtarget>();
-    const auto &MacroFusions = ST.getMacroFusions();
-    if (!MacroFusions.empty()) {
-      ScheduleDAGMI *DAG = createGenericSchedPostRA(C);
-      DAG->addMutation(createMacroFusionDAGMutation(MacroFusions));
-      return DAG;
-    }
-    return nullptr;
-  }
-
   void addIRPasses() override;
   bool addPreISel() override;
   bool addInstSelector() override;