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/CodeGen/SelectionDAG/SelectionDAGBuilder.h b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
index 454a87e..e3668e5 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
@@ -257,7 +257,7 @@
   // TLI - This is information that describes the available target features we
   // need for lowering.  This indicates when operations are unavailable,
   // implemented with a libcall, etc.
-  TargetLowering &TLI;
+  const TargetLowering &TLI;
   SelectionDAG &DAG;
   const TargetData *TD;
   AliasAnalysis *AA;
@@ -303,7 +303,7 @@
 
   LLVMContext *Context;
 
-  SelectionDAGBuilder(SelectionDAG &dag, TargetLowering &tli,
+  SelectionDAGBuilder(SelectionDAG &dag, const TargetLowering &tli,
                       FunctionLoweringInfo &funcinfo,
                       CodeGenOpt::Level ol)
     : SDNodeOrder(0), TLI(tli), DAG(dag), FuncInfo(funcinfo), OptLevel(ol),