[Autobackout][FuncReg]Revert of change: d69545e

 add CFGSimplification and JumpThreading passes back for correctness

We hit an nonconformance issue when disabling global opt in staged
compilation. CFGSimplification and JumpThreading are the culprit passes
and cannot be disabled

Author: houjenko

IGC/Compiler/CISACodeGen/ShaderCodeGen.cpp

@@ -1597,17 +1597,6 @@ void OptimizeIR(CodeGenContext* const pContext)
                 {
                     mpm.add(llvm::createGVNPass());
                 }
-
-                mpm.add(llvm::createCFGSimplificationPass());
-
-                // Conditions apply just as above due to problems with atomics
-                // (see comment above for details).
-                if (!pContext->m_instrTypes.hasAtomics && !extensiveShader(pContext))
-                {
-                    // After lowering 'switch', run jump threading to remove redundant jumps.
-                    mpm.add(llvm::createJumpThreadingPass());
-                }
-
             }
             if (IGC_IS_FLAG_DISABLED(DisableImmConstantOpt))
             {