[OpenMP] Add Module metadata for OpenMP compilation

[jhuber6]

Summary

This patch adds a module level metadata flag indicating that the module
was compiled with the -fopenmp flag. This will make it easier for
passes like OpenMPOpt to determine if it should be run.

[jdoerfert]

tests missing.

[jhuber6]

Addings tests and a module flag for openmp target devices.

[jdoerfert]

LG

[jdoerfert]

clang/lib/CodeGen/CodeGenModule.cpp

705

Why do we need OpenMPRuntime in the conditional?

[jhuber6]

clang/lib/CodeGen/CodeGenModule.cpp

705

Probably don't explicitly need it, I'll remove it.

[jhuber6]

Removing runtime check.

clang/lib/CodeGen/CodeGenModule.cpp

if (LangOpts.CUDAIsDevice && getTriple().isNVPTX()) {
     // Indicate whether __nvvm_reflect should be configured to flush denormal
     // floating point values to 0.  (This corresponds to its "__CUDA_FTZ"
     // property.)
     getModule().addModuleFlag(llvm::Module::Override, "nvvm-reflect-ftz",
                               CodeGenOpts.FP32DenormalMode.Output !=
                                   llvm::DenormalMode::IEEE);
   }
 
+  // Indicate whether this Module was compiled with -fopenmp
+  if (getLangOpts().OpenMP && !getLangOpts().OpenMPSimd)
+    getModule().addModuleFlag(llvm::Module::Max, "openmp", LangOpts.OpenMP);
+
   // Emit OpenCL specific module metadata: OpenCL/SPIR version.
   if (LangOpts.OpenCL) {
     EmitOpenCLMetadata();
     // Emit SPIR version.
     if (getTriple().isSPIR()) {
       // SPIR v2.0 s2.12 - The SPIR version used by the module is stored in the
       // opencl.spir.version named metadata.
       // C++ is backwards compatible with OpenCL v2.0.
       auto Version = LangOpts.OpenCLCPlusPlus ? 200 : LangOpts.OpenCLVersion;
       llvm::Metadata *SPIRVerElts[] = {