Remove the TargetMachine forwards for TargetSubtargetInfo based
information and update all callers. No functional change.

llvm-svn: 214781
diff --git a/llvm/lib/CodeGen/BasicTargetTransformInfo.cpp b/llvm/lib/CodeGen/BasicTargetTransformInfo.cpp
index d639101..24bc570 100644
--- a/llvm/lib/CodeGen/BasicTargetTransformInfo.cpp
+++ b/llvm/lib/CodeGen/BasicTargetTransformInfo.cpp
@@ -42,7 +42,9 @@
   /// Estimate the cost overhead of SK_Alternate shuffle.
   unsigned getAltShuffleOverhead(Type *Ty) const;
 
-  const TargetLoweringBase *getTLI() const { return TM->getTargetLowering(); }
+  const TargetLoweringBase *getTLI() const {
+    return TM->getSubtargetImpl()->getTargetLowering();
+  }
 
 public:
   BasicTTI() : ImmutablePass(ID), TM(nullptr) {