[Slice node] Add support for steps attribute

[ponnamsairam]

Hey ,
we converted a word language model(Pytorch Model) having LSTM to ONNX format
when we are trying to compile this model with model-compiler we are getting this kind of error
it will be helpful if we get any suggestions!

./bin/model-compiler -m /home/sairam/wordmodel.onnx -emit-bundle=/home/sairam -backend=CPU
WARNING: Logging before InitGoogleLogging() is written to STDERR
F0108 15:51:33.261059 8809 Error.cpp:119] exitOnError(Error) got an unexpected ErrorValue:
Error message: Steps is not currently supported.
Error return stack:
/home/glow/lib/Importer/ONNXModelLoader.cpp:482
/home/glow/lib/Importer/ONNXModelLoader.cpp:2309
/home/glow/lib/Importer/ONNXModelLoader.cpp:2402
/home/glow/lib/Importer/ONNXModelLoader.cpp:2416
*** Check failure stack trace: ***
#0 0x00000000007d515a llvm::sys::PrintStackTrace(llvm::raw_ostream&) (./bin/model-compiler+0x7d515a)
#1 0x00000000007d30ec llvm::sys::RunSignalHandlers() (./bin/model-compiler+0x7d30ec)
#2 0x00000000007d3257 SignalHandler(int) (./bin/model-compiler+0x7d3257)
#3 0x00007f627ae3e390 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x11390)
#4 0x00007f6279fc8428 gsignal (/lib/x86_64-linux-gnu/libc.so.6+0x35428)
#5 0x00007f6279fca02a abort (/lib/x86_64-linux-gnu/libc.so.6+0x3702a)
#6 0x00007f627ac07e49 (/usr/lib/x86_64-linux-gnu/libglog.so.0+0x9e49)
#7 0x00007f627ac095cd (/usr/lib/x86_64-linux-gnu/libglog.so.0+0xb5cd)
#8 0x00007f627ac0b433 google::LogMessage::SendToLog() (/usr/lib/x86_64-linux-gnu/libglog.so.0+0xd433)
#9 0x00007f627ac0915b google::LogMessage::Flush() (/usr/lib/x86_64-linux-gnu/libglog.so.0+0xb15b)
#10 0x00007f627ac0be1e google::LogMessageFatal::~LogMessageFatal() (/usr/lib/x86_64-linux-gnu/libglog.so.0+0xde1e)
#11 0x000000000279929c glow::detail::exitOnError(char const*, unsigned long, glow::detail::GlowError) /home/tcs/glow/lib/Support/Error.cpp:122:0
#12 0x00000000006c9463 glow::ONNXModelLoader::ONNXModelLoader(std::__cxx11::basic_string<char, std::char_traits, std::allocator > const&, llvm::ArrayRef<char const*>, llvm::ArrayRef<glow::Type const*>, glow::Function&, glow::detail::GlowError*, bool) /home/tcs/glow/lib/Importer/ONNXModelLoader.cpp:2416:0
#13 0x000000000051777b main /home/tcs/glow/tools/loader/ModelCompiler.cpp:59:0
#14 0x00007f6279fb3830 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x20830)
#15 0x00000000004ee089 _start (./bin/model-compiler+0x4ee089)
Aborted (core dumped)
@mciprian13

[jfix71]

Hi @ponnamsairam, We do not currently support steps for ONNX's Slice. To fix this, support needs to be added here instead of the error message:

glow/lib/Importer/ONNXModelLoader.cpp

Lines 538 to 539 in 0b0460a

	RETURN_ERR_IF_NOT(op.input_size() == 5,
	"Steps is not currently supported.");