[llvm-mca] Set the Selection strategy to Default if nullptr is passed.

* Set (not reset) the strategy in Scheduler::setCustomStrategyImpl()

llvm-svn: 340566
diff --git a/llvm/tools/llvm-mca/Scheduler.h b/llvm/tools/llvm-mca/Scheduler.h
index 37ebdb4..ed138fd 100644
--- a/llvm/tools/llvm-mca/Scheduler.h
+++ b/llvm/tools/llvm-mca/Scheduler.h
@@ -430,6 +430,11 @@
   std::vector<InstRef> ReadySet;
   std::vector<InstRef> IssuedSet;
 
+  /// Verify the given selection strategy and set the Strategy member
+  /// accordingly.  If no strategy is provided, the DefaultSchedulerStrategy is
+  /// used.
+  void initializeStrategy(std::unique_ptr<SchedulerStrategy> S);
+
   /// Issue an instruction without updating the ready queue.
   void issueInstructionImpl(
       InstRef &IR,
@@ -446,16 +451,19 @@
 
 public:
   Scheduler(const llvm::MCSchedModel &Model, LSUnit *Lsu)
-      : LSU(Lsu), Strategy(llvm::make_unique<DefaultSchedulerStrategy>()),
-        Resources(llvm::make_unique<ResourceManager>(Model)) {}
+      : LSU(Lsu), Resources(llvm::make_unique<ResourceManager>(Model)) {
+    initializeStrategy(nullptr);
+  }
   Scheduler(const llvm::MCSchedModel &Model, LSUnit *Lsu,
             std::unique_ptr<SchedulerStrategy> SelectStrategy)
-      : LSU(Lsu), Strategy(std::move(SelectStrategy)),
-        Resources(llvm::make_unique<ResourceManager>(Model)) {}
+      : LSU(Lsu), Resources(llvm::make_unique<ResourceManager>(Model)) {
+    initializeStrategy(std::move(SelectStrategy));
+  }
   Scheduler(std::unique_ptr<ResourceManager> RM, LSUnit *Lsu,
             std::unique_ptr<SchedulerStrategy> SelectStrategy)
-      : LSU(Lsu), Strategy(std::move(SelectStrategy)),
-        Resources(std::move(RM)) {}
+      : LSU(Lsu), Resources(std::move(RM)) {
+    initializeStrategy(std::move(SelectStrategy));
+  }
 
   // Stalls generated by the scheduler.
   enum Status {