diff --git a/llvm/lib/Target/AMDGPU/SIFrameLowering.cpp b/llvm/lib/Target/AMDGPU/SIFrameLowering.cpp
--- a/llvm/lib/Target/AMDGPU/SIFrameLowering.cpp
+++ b/llvm/lib/Target/AMDGPU/SIFrameLowering.cpp
@@ -565,7 +565,7 @@
     // reserved input we needed. Also for PAL, make sure we don't clobber
     // the GIT pointer passed in SGPR0 or SGPR8.
     if (!MRI.isPhysRegUsed(Reg) && MRI.isAllocatable(Reg) &&
-        !TRI->isSubRegisterEq(Reg, GITPtrLoReg)) {
+        (!GITPtrLoReg || !TRI->isSubRegisterEq(Reg, GITPtrLoReg))) {
       MRI.replaceRegWith(ScratchRsrcReg, Reg);
       MFI->setScratchRSrcReg(Reg);
       return Reg;