This patch changes the ownership of TLOF from TargetLoweringBase to TargetMachine so that different subtargets could share the TLOF effectively

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221878 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Target/TargetLowering.h

@@ -137,10 +137,10 @@ public:
     llvm_unreachable("Invalid content kind");
   }
 
-  /// NOTE: The constructor takes ownership of TLOF.
+  /// NOTE: The TargetMachine owns TLOF.
   explicit TargetLoweringBase(const TargetMachine &TM,
                               const TargetLoweringObjectFile *TLOF);
-  virtual ~TargetLoweringBase();
+  virtual ~TargetLoweringBase() {}
 
 protected:
   /// \brief Initialize all of the actions to default values.

include/llvm/Target/TargetMachine.h

@@ -44,6 +44,7 @@ class ScalarTargetTransformInfo;
 class VectorTargetTransformInfo;
 class formatted_raw_ostream;
 class raw_ostream;
+class TargetLoweringObjectFile;
 
 // The old pass manager infrastructure is hidden in a legacy namespace now.
 namespace legacy {
@@ -102,6 +103,9 @@ public:
   virtual const TargetSubtargetInfo *getSubtargetImpl(const Function &) const {
     return getSubtargetImpl();
   }
+  virtual TargetLoweringObjectFile *getObjFileLowering() const {
+    return nullptr;
+  }
 
   /// getSubtarget - This method returns a pointer to the specified type of
   /// TargetSubtargetInfo.  In debug builds, it verifies that the object being