[clang] [Clang] Check features of tune CPU against target CPU (PR #68861)

[Chen Zheng via cfe-commits]

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@@ -833,6 +833,22 @@ TargetInfo::CreateTargetInfo(DiagnosticsEngine &Diags,
   if (!Target->handleTargetFeatures(Opts->Features, Diags))
     return nullptr;
 
+  // If TuneCPU is set, check if it contains all instruction sets needed by
+  // current feature map.
+  if (!Opts->TuneCPU.empty() && Opts->TuneCPU != Opts->CPU) {
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chenzheng1030 wrote:

Can this handle the case that we use default cpu(i.e. no -mcpu set)?

https://github.com/llvm/llvm-project/pull/68861