Honor 'optnone' functions in the pre-RA MI Scheduler.

[atrick]

LGTM

[probinson]

No test?

[mcrosier]

In D16366#331374, @probinson wrote:

No test?

Sure. I'll put one together.

[probinson]

In D16366#331379, @mcrosier wrote:

In D16366#331374, @probinson wrote:

No test?

Sure. I'll put one together.

Maybe adding a line to test/Feature/optnone-llc.ll would be enough?

[mcrosier]

I decided on a slightly different patch (with a test case), which was committed in r258363. If the function is marked optnone neither the subtarget or the -enable-misched command line option will enable the scheduler.

lib/CodeGen/MachineScheduler.cpp

 /// scheduler must update the RegionBegin and RegionEnd positions cached by
 /// ScheduleDAGInstrs whenever adding or removing instructions. A much simpler
 /// design would be to split blocks at scheduling boundaries, but LLVM has a
 /// general bias against block splitting purely for implementation simplicity.
 bool MachineScheduler::runOnMachineFunction(MachineFunction &mf) {
   if (EnableMachineSched.getNumOccurrences()) {
     if (!EnableMachineSched)
       return false;
-  } else if (!mf.getSubtarget().enableMachineScheduler())
+  } else {
+    if (skipOptnoneFunction(*mf.getFunction()))
       return false;
+    if (!mf.getSubtarget().enableMachineScheduler())
+      return false;
+  }
 
   DEBUG(dbgs() << "Before MISched:\n"; mf.print(dbgs()));
 
   // Initialize the context of the pass.
   MF = &mf;
   MLI = &getAnalysis<MachineLoopInfo>();
   MDT = &getAnalysis<MachineDominatorTree>();
   PassConfig = &getAnalysis<TargetPassConfig>();