[clang] [llvm] [fatlto] Add coroutine passes when using FatLTO with ThinLTO (PR #134434)

[Vitaly Buka via llvm-commits]

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@@ -1692,6 +1692,19 @@ PassBuilder::buildFatLTODefaultPipeline(OptimizationLevel Level, bool ThinLTO,
   if (ThinLTO && PGOOpt && PGOOpt->Action == PGOOptions::SampleUse)
     MPM.addPass(buildThinLTODefaultPipeline(Level, /*ImportSummary=*/nullptr));
   else {
+    // ModuleSimplification does not run the coroutine passes for
+    // ThinLTOPreLink, so we need the coroutine passes to run for ThinLTO
+    // builds, otherwise they will miscompile.
+    if (ThinLTO) {
+      // TODO: replace w/ buildCoroWrapper() when it takes phase and level into
+      // consideration.
+      CGSCCPassManager CGPM;
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vitalybuka wrote:

maybe better to use buildCoroWrapper?

https://github.com/llvm/llvm-project/pull/134434