[llvm] [AMDGPU] Initialize FrameOffsetReg for amdgpu_cs_chain functions (PR #165518)

[via llvm-commits]

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@@ -1408,11 +1408,12 @@ void SIFrameLowering::emitEpilogue(MachineFunction &MF,
       LiveUnits.addReg(FramePtrRegScratchCopy);
     }
 
-    emitCSRSpillRestores(MF, MBB, MBBI, DL, LiveUnits, FramePtrReg,
+    emitCSRSpillRestores(MF, MBB, MBBI, DL, LiveUnits,
+                         FuncInfo->isChainFunction() ? Register() : FramePtrReg,
                          FramePtrRegScratchCopy);
   }
 
-  if (FPSaved) {
+  if (FPSaved && !FuncInfo->isChainFunction()) {
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jofrn wrote:

Yes, they can be merged. Thank you!

https://github.com/llvm/llvm-project/pull/165518