[clang] [llvm] [clang][llvm][fatlto] Avoid cloning modules in FatLTO (PR #72180)

[Teresa Johnson via cfe-commits]

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@@ -810,7 +810,7 @@ void EmitAssemblyHelper::RunOptimizationPipeline(
   // Only enable CGProfilePass when using integrated assembler, since
   // non-integrated assemblers don't recognize .cgprofile section.
   PTO.CallGraphProfile = !CodeGenOpts.DisableIntegratedAS;
-  PTO.UnifiedLTO = CodeGenOpts.UnifiedLTO;
+  PTO.UnifiedLTO = CodeGenOpts.UnifiedLTO || CodeGenOpts.FatLTO;
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teresajohnson wrote:

Won't your change to lib/Driver/ToolChains/Clang.cpp below mean that CodeGenOpts.UnifiedLTO will always be set with FatLTO? Do we thus need this change or the one further below for the module flag (and maybe add an assert that UnifiedLTO is set of FatLTO is set)?

https://github.com/llvm/llvm-project/pull/72180