[OpenMP] Run the OpenMPOpt module pass at O1

[jhuber6]

Summary

Now that the OpenMPOpt module pass include important optimizations for removing
globalization from offloading regions it should be run at a lower optimization
level.

[jdoerfert]

LGTM. Since this affects only modules compiled with -fopenmp it should be OK to run OpenMPOpt at O1.

[jhuber6]

In D105056#2845238, @jdoerfert wrote:

LGTM. Since this affects only modules compiled with -fopenmp it should be OK to run OpenMPOpt at O1.

Should I put it on the CGSCC pass as well then?

[jhuber6]

Fixing tests

llvm/lib/Passes/PassBuilder.cpp

if (Phase != ThinOrFullLTOPhase::ThinLTOPreLink &&
       // imported available_externally functions look unreferenced and are
       // removed.
       MPM.addPass(
           PGOIndirectCallPromotion(true /* IsInLTO */, true /* SamplePGO */));
   }
 
   // Try to perform OpenMP specific optimizations on the module. This is a
   // (quick!) no-op if there are no OpenMP runtime calls present in the module.
-  if (Level == OptimizationLevel::O2 || Level == OptimizationLevel::O3)
+  if (Level != OptimizationLevel::O0)
     MPM.addPass(OpenMPOptPass());
 
   if (AttributorRun & AttributorRunOption::MODULE)
     MPM.addPass(AttributorPass());
 
   // Lower type metadata and the type.test intrinsic in the ThinLTO
   // post link pipeline after ICP. This is to enable usage of the type
   // tests in ICP sequences.