[clang] [Clang] Do not emit multi-gpu warning if they are all the same (PR #185490)

[Matt Arsenault via cfe-commits]

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@@ -735,11 +736,10 @@ AMDGPUToolChain::TranslateArgs(const DerivedArgList &Args, StringRef BoundArch,
           << llvm::toString(GPUsOrErr.takeError()) << "-mcpu";
     } else {
       auto &GPUs = *GPUsOrErr;
-      if (GPUs.size() > 1) {
+      if (llvm::SmallSet<std::string, 1>(GPUs.begin(), GPUs.end()).size() > 1)
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arsenm wrote:

SmallString? Also use the set to start instead of creating the temporary? 

https://github.com/llvm/llvm-project/pull/185490