Stub out a PostMachineScheduler pass.

Placeholder and boilerplate for a PostRA MachineScheduler pass.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@198120 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/Passes.cpp

@@ -88,6 +88,14 @@ PrintMachineInstrs("print-machineinstrs", cl::ValueOptional,
                    cl::desc("Print machine instrs"),
                    cl::value_desc("pass-name"), cl::init("option-unspecified"));
 
+// Temporary option to allow experimenting with MachineScheduler as a post-RA
+// scheduler. Targets can "properly" enable this with
+// substitutePass(&PostRASchedulerID, &MachineSchedulerID); Ideally it wouldn't
+// be part of the standard pass pipeline, and the target would just add a PostRA
+// scheduling pass wherever it wants.
+static cl::opt<bool> MISchedPostRA("misched-postra", cl::Hidden,
+  cl::desc("Run MachineScheduler post regalloc (independent of preRA sched)"));
+
 // Experimental option to run live interval analysis early.
 static cl::opt<bool> EarlyLiveIntervals("early-live-intervals", cl::Hidden,
     cl::desc("Run live interval analysis earlier in the pipeline"));
@@ -525,7 +533,10 @@ void TargetPassConfig::addMachinePasses() {
 
   // Second pass scheduler.
   if (getOptLevel() != CodeGenOpt::None) {
-    addPass(&PostRASchedulerID);
+    if (MISchedPostRA)
+      addPass(&PostMachineSchedulerID);
+    else
+      addPass(&PostRASchedulerID);
     printAndVerify("After PostRAScheduler");
   }