[MLIR] Add a flag to control ngraph dialect fusion pass. (#4362)

* [MLIR] Add a flag to control ngraph dialect fusion pass.

* Address PR feedback.
Co-authored-by: Scott Cyphers <diyessi@users.noreply.github.com>

src/contrib/mlir/core/compiler.cpp

@@ -60,6 +60,11 @@
 // Defines a new LLVM debug type for this file to be used by LLVM_DEBUG macro.
 #define DEBUG_TYPE "mlir-compiler"
 
+static llvm::cl::opt<bool> clEnableNgKernelLibFusion(
+    "ngraph-kernel-lib-fusion",
+    llvm::cl::init(false),
+    llvm::cl::desc("Enable the ngraph pass that fuses ops to use kernel library"));
+
 using llvm::SmallVector;
 using llvm::StringRef;
 using llvm::ArrayRef;
@@ -125,7 +130,10 @@ void MLIRCompiler::buildNgDialectModule()
 void MLIRCompiler::optimizeNgDialect()
 {
     mlir::PassManager pm(&m_context);
-    pm.addPass(ngraph::pass::createNgDialectFusedOpsPass());
+    if (clEnableNgKernelLibFusion)
+    {
+        pm.addPass(ngraph::pass::createNgDialectFusedOpsPass());
+    }
 
     // Apply any generic pass manager command line options.
     mlir::applyPassManagerCLOptions(pm);