Have MachineFunction cache a pointer to the subtarget to make lookups
shorter/easier and have the DAG use that to do the same lookup. This
can be used in the future for TargetMachine based caching lookups from
the MachineFunction easily.

Update the MIPS subtarget switching machinery to update this pointer
at the same time it runs.

llvm-svn: 214838
diff --git a/llvm/lib/Target/MSP430/MSP430FrameLowering.cpp b/llvm/lib/Target/MSP430/MSP430FrameLowering.cpp
index 8ab83d7..2902acf 100644
--- a/llvm/lib/Target/MSP430/MSP430FrameLowering.cpp
+++ b/llvm/lib/Target/MSP430/MSP430FrameLowering.cpp
@@ -44,8 +44,7 @@
   MachineFrameInfo *MFI = MF.getFrameInfo();
   MSP430MachineFunctionInfo *MSP430FI = MF.getInfo<MSP430MachineFunctionInfo>();
   const MSP430InstrInfo &TII =
-      *static_cast<const MSP430InstrInfo *>(
-          MF.getTarget().getSubtargetImpl()->getInstrInfo());
+      *static_cast<const MSP430InstrInfo *>(MF.getSubtarget().getInstrInfo());
 
   MachineBasicBlock::iterator MBBI = MBB.begin();
   DebugLoc DL = MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc();
@@ -110,8 +109,7 @@
   const MachineFrameInfo *MFI = MF.getFrameInfo();
   MSP430MachineFunctionInfo *MSP430FI = MF.getInfo<MSP430MachineFunctionInfo>();
   const MSP430InstrInfo &TII =
-      *static_cast<const MSP430InstrInfo *>(
-          MF.getTarget().getSubtargetImpl()->getInstrInfo());
+      *static_cast<const MSP430InstrInfo *>(MF.getSubtarget().getInstrInfo());
 
   MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr();
   unsigned RetOpcode = MBBI->getOpcode();
@@ -191,8 +189,7 @@
   if (MI != MBB.end()) DL = MI->getDebugLoc();
 
   MachineFunction &MF = *MBB.getParent();
-  const TargetInstrInfo &TII =
-      *MF.getTarget().getSubtargetImpl()->getInstrInfo();
+  const TargetInstrInfo &TII = *MF.getSubtarget().getInstrInfo();
   MSP430MachineFunctionInfo *MFI = MF.getInfo<MSP430MachineFunctionInfo>();
   MFI->setCalleeSavedFrameSize(CSI.size() * 2);
 
@@ -218,8 +215,7 @@
   if (MI != MBB.end()) DL = MI->getDebugLoc();
 
   MachineFunction &MF = *MBB.getParent();
-  const TargetInstrInfo &TII =
-      *MF.getTarget().getSubtargetImpl()->getInstrInfo();
+  const TargetInstrInfo &TII = *MF.getSubtarget().getInstrInfo();
 
   for (unsigned i = 0, e = CSI.size(); i != e; ++i)
     BuildMI(MBB, MI, DL, TII.get(MSP430::POP16r), CSI[i].getReg());
@@ -231,8 +227,7 @@
 eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
                               MachineBasicBlock::iterator I) const {
   const MSP430InstrInfo &TII =
-      *static_cast<const MSP430InstrInfo *>(
-          MF.getTarget().getSubtargetImpl()->getInstrInfo());
+      *static_cast<const MSP430InstrInfo *>(MF.getSubtarget().getInstrInfo());
   unsigned StackAlign = getStackAlignment();
 
   if (!hasReservedCallFrame(MF)) {