[llvm] [AMDGPU] Enable serializing of allocated preload kernarg SGPRs info (PR #168374)

[Matt Arsenault via llvm-commits]

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@@ -2027,6 +2027,35 @@ bool GCNTargetMachine::parseMachineFunctionInfo(
                              MFI->ArgInfo.WorkItemIDZ, 0, 0)))
     return true;
 
+  // Parse FirstKernArgPreloadReg separately, since it's a Register,
+  // not ArgDescriptor.
+  if (YamlMFI.ArgInfo && YamlMFI.ArgInfo->FirstKernArgPreloadReg) {
+    const auto &A = *YamlMFI.ArgInfo->FirstKernArgPreloadReg;
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arsenm wrote:

No auto 

https://github.com/llvm/llvm-project/pull/168374