implement __builtin_return_addr(0) on ppc.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@44700 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/PowerPC/PPCMachineFunctionInfo.h

@@ -27,18 +27,29 @@ private:
   /// when using frame pointers (dyna_add, dyna_sub.)
   int FramePointerSaveIndex;
   
-  /// UsesLR - Indicates whether LR is used in the current function.
+  /// ReturnAddrSaveIndex - Frame index of where the return address is stored.
   ///
+  int ReturnAddrSaveIndex;
+
+  /// UsesLR - Indicates whether LR is used in the current function.  This is
+  /// only valid after the initial scan of the function by PEI.
   bool UsesLR;
 
+  /// LRStoreRequired - The bool indicates whether there is some explicit use of
+  /// the LR/LR8 stack slot that is not obvious from scanning the code.  This
+  /// requires that the code generator produce a store of LR to the stack on
+  /// entry, even though LR may otherwise apparently not be used.
+  bool LRStoreRequired;
 public:
-  PPCFunctionInfo(MachineFunction& MF) 
-  : FramePointerSaveIndex(0)
-  {}
+  PPCFunctionInfo(MachineFunction &MF) 
+    : FramePointerSaveIndex(0), ReturnAddrSaveIndex(0), LRStoreRequired(false){}
 
   int getFramePointerSaveIndex() const { return FramePointerSaveIndex; }
   void setFramePointerSaveIndex(int Idx) { FramePointerSaveIndex = Idx; }
   
+  int getReturnAddrSaveIndex() const { return ReturnAddrSaveIndex; }
+  void setReturnAddrSaveIndex(int idx) { ReturnAddrSaveIndex = idx; }
+  
   /// UsesLR - This is set when the prolog/epilog inserter does its initial scan
   /// of the function, it is true if the LR/LR8 register is ever explicitly
   /// accessed/clobbered in the machine function (e.g. by calls and movpctolr,
@@ -46,6 +57,9 @@ public:
   void setUsesLR(bool U) { UsesLR = U; }
   bool usesLR() const    { return UsesLR; }
 
+  void setLRStoreRequired() { LRStoreRequired = true; }
+  bool isLRStoreRequired() const { return LRStoreRequired; }
+  
 };
 
 } // end of namespace llvm