Use const qualifiers with TargetLowering. This eliminates several
const_casts, and it reinforces the design of the Target classes being
immutable.

SelectionDAGISel::IsLegalToFold is now a static member function, because
PIC16 uses it in an unconventional way. There is more room for API
cleanup here.

And PIC16's AsmPrinter no longer uses TargetLowering.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@101635 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/ARM/ARMTargetMachine.h b/lib/Target/ARM/ARMTargetMachine.h
index c32f16c..4e205df 100644
--- a/lib/Target/ARM/ARMTargetMachine.h
+++ b/lib/Target/ARM/ARMTargetMachine.h
@@ -71,8 +71,8 @@
     return &InstrInfo.getRegisterInfo();
   }
 
-  virtual       ARMTargetLowering *getTargetLowering() const {
-    return const_cast<ARMTargetLowering*>(&TLInfo);
+  virtual const ARMTargetLowering *getTargetLowering() const {
+    return &TLInfo;
   }
 
   virtual const ARMInstrInfo     *getInstrInfo() const { return &InstrInfo; }
@@ -97,8 +97,8 @@
     return &InstrInfo->getRegisterInfo();
   }
 
-  virtual ARMTargetLowering *getTargetLowering() const {
-    return const_cast<ARMTargetLowering*>(&TLInfo);
+  virtual const ARMTargetLowering *getTargetLowering() const {
+    return &TLInfo;
   }
 
   /// returns either Thumb1InstrInfo or Thumb2InstrInfo