[SPARC] Switch to the Machine Scheduler.

The (mostly-deprecated) SelectionDAG-based ILPListDAGScheduler scheduler
was making poor scheduling decisions, causing high register pressure and
extraneous register spills.

Switching to the newer machine scheduler generates better code -- even
without there being a machine model defined for SPARC yet.

llvm-svn: 247315

Author: jyknight

llvm/lib/Target/Sparc/SparcSubtarget.cpp

@@ -81,3 +81,7 @@ int SparcSubtarget::getAdjustedFrameSize(int frameSize) const {
   }
   return frameSize;
 }
+
+bool SparcSubtarget::enableMachineScheduler() const {
+  return true;
+}

llvm/lib/Target/Sparc/SparcSubtarget.h

@@ -60,6 +60,8 @@ class SparcSubtarget : public SparcGenSubtargetInfo {
     return &TSInfo;
   }
 
+  bool enableMachineScheduler() const override;
+
   bool isV9() const { return IsV9; }
   bool isVIS() const { return IsVIS; }
   bool isVIS2() const { return IsVIS2; }
@@ -85,7 +87,6 @@ class SparcSubtarget : public SparcGenSubtargetInfo {
   /// returns adjusted framesize which includes space for register window
   /// spills and arguments.
   int getAdjustedFrameSize(int stackSize) const;
-
 };
 
 } // end namespace llvm