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/PowerPC/PPCISelDAGToDAG.cpp b/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
index 1e32384..3d9f8aa 100644
--- a/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
+++ b/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
@@ -16,7 +16,6 @@
 #include "PPC.h"
 #include "PPCPredicates.h"
 #include "PPCTargetMachine.h"
-#include "PPCISelLowering.h"
 #include "PPCHazardRecognizers.h"
 #include "llvm/CodeGen/MachineInstrBuilder.h"
 #include "llvm/CodeGen/MachineFunction.h"
@@ -41,8 +40,8 @@
   /// instructions for SelectionDAG operations.
   ///
   class PPCDAGToDAGISel : public SelectionDAGISel {
-    PPCTargetMachine &TM;
-    PPCTargetLowering &PPCLowering;
+    const PPCTargetMachine &TM;
+    const PPCTargetLowering &PPCLowering;
     const PPCSubtarget &PPCSubTarget;
     unsigned GlobalBaseReg;
   public: