[Flang][OpenMP] Remove TODO for shared and two values of default clause

[kiranchandramohan]

Summary

Shared is the default behaviour in the IR, so no handling is required.
Default clause with shared or none do not require any handling since
Shared is the default behaviour in the IR and None is only required
for semantic checks.

This patch is carved out from D123930 to remove couple of false TODOs.

Co-authored-by: Nimish Mishra <[e-mail]>

[kiranchandramohan]

I need this to enable an application. Assuming D123930 will take a few more days.

[kiranchandramohan]

clang-format fix

[peixin]

Thanks @kiranchandramohan for making progress for LLVM Flang OpenMP on application, no matter what the application is :).

flang/lib/Lower/OpenMP.cpp

615

It seems american english is preferred for llvm.

625

behavior

[kiranchandramohan]

Thanks @peixin. :)

Will change spelling while submitting. Application is SNAP. There is still one issue with the aggregate setting of the OpenMPIRBuilder.

flang/lib/Lower/OpenMP.cpp

if (const auto &ifClause =
       genAllocateClause(converter, allocateClause->v, allocatorOperands,
                         allocateOperands);
     } else if (std::get_if<Fortran::parser::OmpClause::Private>(&clause.u) ||
                std::get_if<Fortran::parser::OmpClause::Firstprivate>(
                    &clause.u) ||
                std::get_if<Fortran::parser::OmpClause::Copyin>(&clause.u)) {
       // Privatisation and copyin clauses are handled elsewhere.
       continue;
+    } else if (std::get_if<Fortran::parser::OmpClause::Shared>(&clause.u)) {
+      // Shared is the default behavior in the IR, so no handling is required.
+      continue;
+    } else if (const auto &defaultClause =
+                   std::get_if<Fortran::parser::OmpClause::Default>(
+                       &clause.u)) {
+      if ((defaultClause->v.v ==
+           Fortran::parser::OmpDefaultClause::Type::Shared) ||
+          (defaultClause->v.v ==
+           Fortran::parser::OmpDefaultClause::Type::None)) {
+        // Default clause with shared or none do not require any handling since
+        // Shared is the default behavior in the IR and None is only required
+        // for semantic checks.
+        continue;
+      }
     } else if (std::get_if<Fortran::parser::OmpClause::Threads>(&clause.u)) {
       // Nothing needs to be done for threads clause.
       continue;
     } else if (const auto &finalClause =
                    std::get_if<Fortran::parser::OmpClause::Final>(&clause.u)) {
       mlir::Value finalVal = fir::getBase(converter.genExprValue(
           *Fortran::semantics::GetExpr(finalClause->v), stmtCtx));
       finalClauseOperand = firOpBuilder.createConvert(