[OpenMP] Always inline the OpenMP outlined function

[jhuber6]

Summary

This patch adds the always inline attribute to the outlined functions generated
by OpenMP regions. Because there is only a single instance of this function and
it always has internal linkage it is safe to inline in every instance it is
created. This could potentially lead to performance degredation due to
inflated register counts in the parallel region.

[jdoerfert]

One test needs to be fixed. LG

[jhuber6]

Fix test

[mikerice]

Looks like now omp.outlined functions are marked with both 'noinline' and 'alwaysinline'. See https://bugs.llvm.org/show_bug.cgi?id=51349

clang/lib/CodeGen/CGStmtOpenMP.cpp

static llvm::Function *emitOutlinedFunctionPrologue(
   auto *F =
       llvm::Function::Create(FuncLLVMTy, llvm::GlobalValue::InternalLinkage,
                              FO.FunctionName, &CGM.getModule());
   CGM.SetInternalFunctionAttributes(CD, F, FuncInfo);
   if (CD->isNothrow())
     F->setDoesNotThrow();
   F->setDoesNotRecurse();
 
+  // Always inline the outlined function if optimizations are enabled.
+  if (CGM.getCodeGenOpts().OptimizationLevel != 0)
+    F->addFnAttr(llvm::Attribute::AlwaysInline);
+
   // Generate the function.
   CGF.StartFunction(CD, Ctx.VoidTy, F, FuncInfo, TargetArgs,
                     FO.UIntPtrCastRequired ? FO.Loc : FO.S->getBeginLoc(),
                     FO.UIntPtrCastRequired ? FO.Loc
                                            : CD->getBody()->getBeginLoc());
   unsigned Cnt = CD->getContextParamPosition();
   I = FO.S->captures().begin();
   for (const FieldDecl *FD : RD->fields()) {

 static llvm::Function *emitOutlinedOrderedFunction(CodeGenModule &CGM,
                                                    const CapturedStmt *S,
                                                    SourceLocation Loc) {
   CodeGenFunction CGF(CGM, /*suppressNewContext=*/true);
   CodeGenFunction::CGCapturedStmtInfo CapStmtInfo;
   CGF.CapturedStmtInfo = &CapStmtInfo;
   llvm::Function *Fn = CGF.GenerateOpenMPCapturedStmtFunction(*S, Loc);
   Fn->setDoesNotRecurse();
+  if (CGM.getCodeGenOpts().OptimizationLevel != 0)
+    Fn->addFnAttr(llvm::Attribute::AlwaysInline);
   return Fn;
 }
 
 void CodeGenFunction::EmitOMPOrderedDirective(const OMPOrderedDirective &S) {
   if (S.hasClausesOfKind<OMPDependClause>()) {
     assert(!S.hasAssociatedStmt() &&
            "No associated statement must be in ordered depend construct.");
     for (const auto *DC : S.getClausesOfKind<OMPDependClause>())