1 files changed, 16 insertions, 1 deletions
diff --git a/llvm/lib/Target/TargetSubtargetInfo.cpp b/llvm/lib/Target/TargetSubtargetInfo.cpp
index f624c321ab4..10e8db5925d 100644
--- a/llvm/lib/Target/TargetSubtargetInfo.cpp
+++ b/llvm/lib/Target/TargetSubtargetInfo.cpp
@@ -11,6 +11,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "llvm/Support/CommandLine.h"
 #include "llvm/Target/TargetSubtargetInfo.h"
 #include "llvm/ADT/SmallVector.h"
 using namespace llvm;
@@ -22,6 +23,21 @@ TargetSubtargetInfo::TargetSubtargetInfo() {}
 
 TargetSubtargetInfo::~TargetSubtargetInfo() {}
 
+// Temporary option to compare overall performance change when moving from the
+// SD scheduler to the MachineScheduler pass pipeline. It should be removed
+// before 3.4. The normal way to enable/disable the MachineScheduling pass
+// itself is by using -enable-misched. For targets that already use MI sched
+// (via MySubTarget::enableMachineScheduler()) -misched-bench=false negates the
+// subtarget hook.
+static cl::opt<bool> BenchMachineSched("misched-bench", cl::Hidden,
+    cl::desc("Migrate from the target's default SD scheduler to MI scheduler"));
+
+bool TargetSubtargetInfo::useMachineScheduler() const {
+  if (BenchMachineSched.getNumOccurrences())
+    return BenchMachineSched;
+  return enableMachineScheduler();
+}
+
 bool TargetSubtargetInfo::enableMachineScheduler() const {
   return false;
 }
@@ -38,4 +54,3 @@ bool TargetSubtargetInfo::enablePostRAScheduler(
 bool TargetSubtargetInfo::useAA() const {
   return false;
 }
-