[SYCL][NATIVECPU] Schedule optimization passes in Native CPU pipeline (#14380)

Adds some extra optimization passes after vectorization on Native CPU.

Author: PietroGhg

llvm/lib/SYCLNativeCPUUtils/PipelineSYCLNativeCPU.cpp

@@ -30,7 +30,13 @@
 #include "compiler/utils/work_item_loops_pass.h"
 #include "vecz/pass.h"
 #include "vecz/vecz_target_info.h"
+#include "llvm/IR/PassManager.h"
+#include "llvm/Transforms/AggressiveInstCombine/AggressiveInstCombine.h"
 #include "llvm/Transforms/IPO/AlwaysInliner.h"
+#include "llvm/Transforms/Scalar/DCE.h"
+#include "llvm/Transforms/Scalar/GVN.h"
+#include "llvm/Transforms/Scalar/SROA.h"
+#include "llvm/Transforms/Scalar/SimplifyCFG.h"
 #endif
 
 using namespace llvm;
@@ -65,6 +71,7 @@ void llvm::sycl::utils::addSYCLNativeCPUBackendPasses(
   MPM.addPass(SpecConstantsPass(SpecConstantsPass::HandlingMode::emulation));
   MPM.addPass(ConvertToMuxBuiltinsSYCLNativeCPUPass());
 #ifdef NATIVECPU_USE_OCK
+  MPM.addPass(compiler::utils::PrepareBarriersPass());
   MPM.addPass(compiler::utils::TransferKernelMetadataPass());
   MPM.addPass(FixABIMuxBuiltinsPass());
   // Always enable vectorizer, unless explictly disabled or -O0 is set.
@@ -86,13 +93,20 @@ void llvm::sycl::utils::addSYCLNativeCPUBackendPasses(
     MAM.registerPass(
         [QueryFunc] { return vecz::VeczPassOptionsAnalysis(QueryFunc); });
     MPM.addPass(vecz::RunVeczPass());
+    FunctionPassManager FPM;
+    FPM.addPass(SimplifyCFGPass());
+    FPM.addPass(SROAPass(SROAOptions::ModifyCFG));
+    FPM.addPass(AggressiveInstCombinePass());
+    FPM.addPass(GVNPass(GVNOptions().setMemDep(true)));
+    FPM.addPass(DCEPass());
+    FPM.addPass(SimplifyCFGPass());
+    MPM.addPass(createModuleToFunctionPassAdaptor(std::move(FPM)));
   }
   compiler::utils::WorkItemLoopsPassOptions Opts;
   Opts.IsDebug = IsDebug;
   Opts.ForceNoTail = ForceNoTail;
   MAM.registerPass([] { return compiler::utils::BuiltinInfoAnalysis(); });
   MAM.registerPass([] { return compiler::utils::SubgroupAnalysis(); });
-  MPM.addPass(compiler::utils::PrepareBarriersPass());
   MPM.addPass(compiler::utils::WorkItemLoopsPass(Opts));
   MPM.addPass(compiler::utils::ReplaceLocalModuleScopeVariablesPass());
   MPM.addPass(AlwaysInlinerPass());