[clang] [Clang] Add a flag to include GPU startup files (PR #112025)

[Matt Arsenault via cfe-commits]

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@@ -648,6 +648,15 @@ void amdgpu::Linker::ConstructJob(Compilation &C, const JobAction &JA,
         Args.MakeArgString("-plugin-opt=-mattr=" + llvm::join(Features, ",")));
   }
 
+  if (Args.hasArg(options::OPT_gpustartfiles)) {
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arsenm wrote:

can we make that have a positive pair, like other flags? No gpu prefix? 

https://github.com/llvm/llvm-project/pull/112025