[llvm] [AMDGPU] Restore SP correctly in functions with dynamic allocas (PR #122743)

[Matt Arsenault via llvm-commits]

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@@ -1259,6 +1259,17 @@ void SIFrameLowering::emitEpilogue(MachineFunction &MF,
   Register FramePtrRegScratchCopy;
   Register SGPRForFPSaveRestoreCopy =
       FuncInfo->getScratchSGPRCopyDstReg(FramePtrReg);
+
+  if (MFI.hasVarSizedObjects()) {
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arsenm wrote:

It's any kind of dynamic stack adjustment. I think this is the same conditions as hasFP (that's what I was using in my last attempt at this) 

https://github.com/llvm/llvm-project/pull/122743