Fix PPC64 CR spill location for callee-saved registers

This fixes an ABI bug for non-Darwin PPC64. For the callee-saved condition
registers, the spill location is specified relative to the stack pointer (SP +
8). However, this is not relative to the SP after the new stack frame is
established, but instead relative to the caller's stack pointer (it is stored
into the linkage area of the parent's stack frame).

So, like with the link register, we don't directly spill the CRs with other
callee-saved registers, but just mark them to be spilled during prologue
generation.

In practice, this reverts r179457 for PPC64 (but leaves it in place for PPC32).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179500 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/PowerPC/PPCMachineFunctionInfo.h

@@ -84,6 +84,11 @@ class PPCFunctionInfo : public MachineFunctionInfo {
   /// CRSpillFrameIndex - FrameIndex for CR spill slot for 32-bit SVR4.
   int CRSpillFrameIndex;
 
+  /// If any of CR[2-4] need to be saved in the prologue and restored in the
+  /// epilogue then they are added to this array. This is used for the
+  /// 64-bit SVR4 ABI.
+  SmallVector<unsigned, 3> MustSaveCRs;
+
 public:
   explicit PPCFunctionInfo(MachineFunction &MF) 
     : FramePointerSaveIndex(0),
@@ -154,6 +159,10 @@ public:
 
   int getCRSpillFrameIndex() const { return CRSpillFrameIndex; }
   void setCRSpillFrameIndex(int idx) { CRSpillFrameIndex = idx; }
+
+  const SmallVector<unsigned, 3> &
+    getMustSaveCRs() const { return MustSaveCRs; }
+  void addMustSaveCR(unsigned Reg) { MustSaveCRs.push_back(Reg); }
 };
 
 } // end of namespace llvm