Activate OpenMP translation in MLIR execution engine CAPI.

[rafaelubalmw]

Summary

We've observed that the MLIR Jit Engine fails when the omp dialect is used due to a failure to register OpenMP-related translations. This small patch addresses this issue.

[mehdi_amini]

Can this be tested?

[rafaelubalmw]

Added unit test

The test for this feature creates an MLIR execution engine using the C API with
an MLIR module containing 'omp' ops. The creation of the execution engine instance
would fail if OpenMP translation had not been activated as expected.

[rafaelubalmw]

Hi @mehdi_amini - I currently don't have commit access to the LLVM repo. If you could merge this approved change, that'd be great. Thanks!

mlir/lib/CAPI/ExecutionEngine/ExecutionEngine.cpp

 //===- ExecutionEngine.cpp - C API for MLIR JIT ---------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #include "mlir-c/ExecutionEngine.h"
 #include "mlir/CAPI/ExecutionEngine.h"
 #include "mlir/CAPI/IR.h"
 #include "mlir/CAPI/Support.h"
 #include "mlir/ExecutionEngine/OptUtils.h"
 #include "mlir/Target/LLVMIR/Dialect/Builtin/BuiltinToLLVMIRTranslation.h"
 #include "mlir/Target/LLVMIR/Dialect/LLVMIR/LLVMToLLVMIRTranslation.h"
+#include "mlir/Target/LLVMIR/Dialect/OpenMP/OpenMPToLLVMIRTranslation.h"
 #include "llvm/ExecutionEngine/Orc/Mangling.h"
 #include "llvm/Support/TargetSelect.h"
 
 using namespace mlir;
 
 extern "C" MlirExecutionEngine
 mlirExecutionEngineCreate(MlirModule op, int optLevel, int numPaths,
                           const MlirStringRef *sharedLibPaths,
                           bool enableObjectDump) {
   static bool initOnce = [] {
     llvm::InitializeNativeTarget();
     llvm::InitializeNativeTargetAsmParser(); // needed for inline_asm
     llvm::InitializeNativeTargetAsmPrinter();
     return true;
   }();
   (void)initOnce;
 
   auto &ctx = *unwrap(op)->getContext();
   mlir::registerBuiltinDialectTranslation(ctx);
   mlir::registerLLVMDialectTranslation(ctx);
+  mlir::registerOpenMPDialectTranslation(ctx);
 
   auto tmBuilderOrError = llvm::orc::JITTargetMachineBuilder::detectHost();
   if (!tmBuilderOrError) {
     llvm::errs() << "Failed to create a JITTargetMachineBuilder for the host\n";
     return MlirExecutionEngine{nullptr};
   }
   auto tmOrError = tmBuilderOrError->createTargetMachine();
   if (!tmOrError) {