[clang] [clang][modules-driver] Precompile std modules independently of -o and final phase (PR #199289)

[Chuanqi Xu via cfe-commits]

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@@ -5471,6 +5478,13 @@ void Driver::BuildJobs(Compilation &C) const {
           A->getKind() == clang::driver::Action::BinaryTranslatorJobClass)
         continue;
 
+      if (isa<PrecompileJobAction>(A) && !A->getInputs().empty()) {
+        const Action *FirstAction = A->getInputs().front();
+        if (FirstAction->getType() == types::TY_CXXStdModule ||
+            FirstAction->getType() == types::TY_PP_CXXStdModule)
+          continue;
+      }
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ChuanqiXu9 wrote:

What are we doing here?

https://github.com/llvm/llvm-project/pull/199289