[llvm] [DirectX] Fix build breaks (PR #128556)

[Farzon Lotfi via llvm-commits]

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@@ -22,6 +22,14 @@ namespace llvm {
 struct DirectXRegisterInfo : public DirectXGenRegisterInfo {
   DirectXRegisterInfo() : DirectXGenRegisterInfo(0) {}
   ~DirectXRegisterInfo();
+
+  const MCPhysReg *getCalleeSavedRegs(const MachineFunction *MF) const override;
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farzonl wrote:

Had to implement these overrides to be able to create an instance of `DirectXRegisterInfo` in `llvm/lib/Target/DirectX/DirectXInstrInfo.h`

https://github.com/llvm/llvm-project/pull/128556